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  Subjects -> CHEMISTRY (Total: 846 journals)
    - ANALYTICAL CHEMISTRY (50 journals)
    - CHEMISTRY (597 journals)
    - CRYSTALLOGRAPHY (22 journals)
    - ELECTROCHEMISTRY (25 journals)
    - INORGANIC CHEMISTRY (41 journals)
    - ORGANIC CHEMISTRY (45 journals)
    - PHYSICAL CHEMISTRY (66 journals)

CHEMISTRY (597 journals)                  1 2 3 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 7)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 26)
ACS Catalysis     Full-text available via subscription   (Followers: 31)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 17)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 23)
ACS Macro Letters     Full-text available via subscription   (Followers: 22)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 39)
ACS Nano     Full-text available via subscription   (Followers: 215)
ACS Photonics     Full-text available via subscription   (Followers: 10)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 20)
Acta Chemica Iasi     Open Access   (Followers: 2)
Acta Chimica Sinica     Full-text available via subscription  
Acta Chimica Slovaca     Open Access   (Followers: 1)
Acta Chromatographica     Full-text available via subscription   (Followers: 9)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 5)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 7)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 5)
Advanced Functional Materials     Hybrid Journal   (Followers: 47)
Advanced Science Focus     Free   (Followers: 3)
Advances in Chemical Engineering and Science     Open Access   (Followers: 53)
Advances in Chemical Science     Open Access   (Followers: 12)
Advances in Chemistry     Open Access   (Followers: 12)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 18)
Advances in Drug Research     Full-text available via subscription   (Followers: 22)
Advances in Enzyme Research     Open Access   (Followers: 10)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 14)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 18)
Advances in Nanoparticles     Open Access   (Followers: 12)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 15)
Advances in Polymer Science     Hybrid Journal   (Followers: 40)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 18)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Science and Technology     Full-text available via subscription   (Followers: 10)
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 2)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 65)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 14)
American Journal of Chemistry     Open Access   (Followers: 25)
American Journal of Plant Physiology     Open Access   (Followers: 13)
American Mineralogist     Full-text available via subscription   (Followers: 12)
Analyst     Full-text available via subscription   (Followers: 38)
Angewandte Chemie     Hybrid Journal   (Followers: 152)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 203)
Annales UMCS, Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 1)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 3)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 7)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 14)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antiviral Chemistry and Chemotherapy     Hybrid Journal  
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 6)
Applied Spectroscopy     Full-text available via subscription   (Followers: 22)
Applied Surface Science     Hybrid Journal   (Followers: 26)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 2)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Atomization and Sprays     Full-text available via subscription   (Followers: 3)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 2)
Avances en Quimica     Open Access   (Followers: 1)
Biochemical Pharmacology     Hybrid Journal   (Followers: 9)
Biochemistry     Full-text available via subscription   (Followers: 274)
Biochemistry Insights     Open Access   (Followers: 5)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 9)
Bioinspired Materials     Open Access   (Followers: 3)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 2)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access  
Biomacromolecules     Full-text available via subscription   (Followers: 18)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 6)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 4)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 106)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 99)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 18)
Biosensors     Open Access   (Followers: 2)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 1)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 2)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 24)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 2)
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 2)
Canadian Journal of Chemistry     Full-text available via subscription   (Followers: 10)
Canadian Mineralogist     Full-text available via subscription   (Followers: 3)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 67)
Catalysis for Sustainable Energy     Open Access   (Followers: 6)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 6)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 7)
Cellulose     Hybrid Journal   (Followers: 7)
Cereal Chemistry     Full-text available via subscription   (Followers: 4)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 1)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 12)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 69)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 23)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Full-text available via subscription   (Followers: 19)
Chemical Reviews     Full-text available via subscription   (Followers: 163)
Chemical Science     Open Access   (Followers: 21)
Chemical Technology     Open Access   (Followers: 15)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 4)
Chemical Week     Full-text available via subscription   (Followers: 7)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 55)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 25)
ChemInform     Hybrid Journal   (Followers: 7)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 6)
Chemistry & Biology     Full-text available via subscription   (Followers: 30)
Chemistry & Industry     Hybrid Journal   (Followers: 5)
Chemistry - A European Journal     Hybrid Journal   (Followers: 136)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 15)
Chemistry and Materials Research     Open Access   (Followers: 17)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry International     Hybrid Journal   (Followers: 2)
Chemistry Letters     Full-text available via subscription   (Followers: 43)
Chemistry of Materials     Full-text available via subscription   (Followers: 187)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry-Didactics-Ecology-Metrology     Open Access  
ChemistryOpen     Open Access   (Followers: 2)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 2)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 8)
ChemPlusChem     Hybrid Journal   (Followers: 2)
ChemTexts     Hybrid Journal  
CHIMIA International Journal for Chemistry     Full-text available via subscription   (Followers: 2)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 10)
Chromatographia     Hybrid Journal   (Followers: 23)
Chromatography Research International     Open Access   (Followers: 7)
Clay Minerals     Full-text available via subscription   (Followers: 9)
Cogent Chemistry     Open Access  
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 10)
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 8)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 3)
Combustion Science and Technology     Hybrid Journal   (Followers: 18)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Comprehensive Chemical Kinetics     Full-text available via subscription   (Followers: 2)
Comptes Rendus Chimie     Full-text available via subscription  
Comptes Rendus Physique     Full-text available via subscription   (Followers: 1)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 9)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 12)
Computational Chemistry     Open Access   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 9)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 2)
Copernican Letters     Open Access  
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 5)
Crystal Structure Theory and Applications     Open Access   (Followers: 3)
CrystEngComm     Full-text available via subscription   (Followers: 10)
Current Catalysis     Hybrid Journal   (Followers: 2)
Current Metabolomics     Hybrid Journal   (Followers: 4)
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 9)
Current Research in Chemistry     Open Access   (Followers: 8)
Current Science     Open Access   (Followers: 48)
Dalton Transactions     Full-text available via subscription   (Followers: 18)
Detection     Open Access   (Followers: 2)
Developments in Geochemistry     Full-text available via subscription   (Followers: 2)
Diamond and Related Materials     Hybrid Journal   (Followers: 11)
Dislocations in Solids     Full-text available via subscription  
Doklady Chemistry     Hybrid Journal  
Drying Technology: An International Journal     Hybrid Journal   (Followers: 3)
Eclética Química     Open Access   (Followers: 1)
Ecological Chemistry and Engineering S     Open Access   (Followers: 4)
Ecotoxicology and Environmental Contamination     Open Access  
Educación Química     Open Access   (Followers: 1)
Education for Chemical Engineers     Hybrid Journal   (Followers: 5)
EJNMMI Radiopharmacy and Chemistry     Open Access  
Elements     Full-text available via subscription   (Followers: 2)
Environmental Chemistry     Hybrid Journal   (Followers: 8)
Environmental Chemistry Letters     Hybrid Journal   (Followers: 4)
Environmental Science & Technology Letters     Full-text available via subscription   (Followers: 5)
Environmental Science : Nano     Partially Free   (Followers: 1)
Environmental Toxicology & Chemistry     Hybrid Journal   (Followers: 19)

        1 2 3 | Last

Journal Cover Advanced Functional Materials
  [SJR: 5.21]   [H-I: 203]   [47 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1616-301X - ISSN (Online) 1616-3028
   Published by John Wiley and Sons Homepage  [1582 journals]
  • Covalently Adaptable Elastin-Like Protein–Hyaluronic Acid (ELP–HA)
           Hybrid Hydrogels with Secondary Thermoresponsive Crosslinking for
           Injectable Stem Cell Delivery
    • Authors: Huiyuan Wang; Danqing Zhu, Alexandra Paul, Lei Cai, Annika Enejder, Fan Yang, Sarah C. Heilshorn
      Abstract: Shear-thinning, self-healing hydrogels are promising vehicles for therapeutic cargo delivery due to their ability to be injected using minimally invasive surgical procedures. An injectable hydrogel using a novel combination of dynamic covalent crosslinking with thermoresponsive engineered proteins is presented. Ex situ at room temperature, rapid gelation occurs through dynamic covalent hydrazone bonds by simply mixing two components: hydrazine-modified elastin-like protein (ELP) and aldehyde-modified hyaluronic acid. This hydrogel provides significant mechanical protection to encapsulated human mesenchymal stem cells during syringe needle injection and rapidly recovers after injection to retain the cells homogeneously within a 3D environment. In situ, the ELP undergoes a thermal phase transition, as confirmed by coherent anti-Stokes Raman scattering microscopy observation of dense ELP thermal aggregates. The formation of the secondary network reinforces the hydrogel and results in a tenfold slower erosion rate compared to a control hydrogel without secondary thermal crosslinking. This improved structural integrity enables cell culture for three weeks postinjection, and encapsulated cells maintain their ability to differentiate into multiple lineages, including chondrogenic, adipogenic, and osteogenic cell types. Together, these data demonstrate the promising potential of ELP–HA hydrogels for injectable stem cell transplantation and tissue regeneration.Shear-thinning and self-healing hydrogels containing protein-engineered elastin-like protein and hyaluronic acid are fabricated through dynamic covalent crosslinking, followed by thermoresponsive physical crosslinking for reinforcement and enhanced stability. These hydrogels have highly tunable stiffness, provide delivered stem cells significant mechanical protection, and maintain the cells after delivery in a 3D environment that supports further differentiation.
      PubDate: 2017-05-19T02:35:36.765922-05:
      DOI: 10.1002/adfm.201605609
       
  • Thermal Transport: Thermal Properties of Two Dimensional Layered Materials
           (Adv. Funct. Mater. 19/2017)
    • Authors: Yuxi Wang; Ning Xu, Deyu Li, Jia Zhu
      Abstract: Two-dimensional layered materials (2DLMs) have shown unique and diversified thermal transport properties, such as anomalous size dependent and anisotropic thermal conductivity. In the feature article number 1604134, Jia Zhu and co-workers review the recent progress in the thermal transport of 2DLMs and present potential applications.
      PubDate: 2017-05-16T06:49:15.827864-05:
      DOI: 10.1002/adfm.201770114
       
  • Advances in Two-Dimensional Layered Materials
    • Authors: Shu Ping Lau; Lain-Jong Li, Yang Chai
      PubDate: 2017-05-16T06:49:11.916679-05:
      DOI: 10.1002/adfm.201701403
       
  • Masthead: (Adv. Funct. Mater. 19/2017)
    • PubDate: 2017-05-16T06:49:09.67601-05:0
      DOI: 10.1002/adfm.201770116
       
  • Nanosheet Sensors: Recent Advances in Sensing Applications of
           Two-Dimensional Transition Metal Dichalcogenide Nanosheets and Their
           Composites (Adv. Funct. Mater. 19/2017)
    • Authors: Jianfeng Ping; Zhanxi Fan, Melinda Sindoro, Yibin Ying, Hua Zhang
      Abstract: Two-dimensional (2D) transition metal dichalcogenide (TMD) nanosheets (NSs) possess a unique layered structure and a large surface area as well as outstanding physical, chemical, optical, and electronic properties. In their review, article number 1605817, Hua Zhang and co-workers introduce state-of-art sensing applications of 2D TMD NSs and their composites.
      PubDate: 2017-05-16T06:49:09.629362-05:
      DOI: 10.1002/adfm.201770115
       
  • Contents: (Adv. Funct. Mater. 19/2017)
    • PubDate: 2017-05-16T06:49:09.500375-05:
      DOI: 10.1002/adfm.201770117
       
  • Transition Metal Dichalcogenides: Suppression of Defects and Deep Levels
           Using Isoelectronic Tungsten Substitution in Monolayer MoSe2 (Adv. Funct.
           Mater. 19/2017)
    • Authors: Xufan Li; Alexander A. Puretzky, Xiahan Sang, Santosh KC, Mengkun Tian, Frank Ceballos, Masoud Mahjouri-Samani, Kai Wang, Raymond R. Unocic, Hui Zhao, Gerd Duscher, Valentino R. Cooper, Christopher M. Rouleau, David B. Geohegan, Kai Xiao
      Abstract: In article number 1603850, Kai Xiao and co-workers present a new strategy for suppressing chalcogen defects in 2D transition metal dichalcogenide monolayers, specifically MoSe2 monolayers. Isoelectronic tungsten (W) alloying during monolayer synthesis results in Mo1−xWxSe2. Defect suppression is essential for the development of high performance optoelectronic and electronic devices.
      PubDate: 2017-05-16T06:49:09.43315-05:0
      DOI: 10.1002/adfm.201770119
       
  • Biosensors: The Roadmap of Graphene-Based Optical Biochemical Sensors
           (Adv. Funct. Mater. 19/2017)
    • Authors: Bannur Nanjunda Shivananju; Wenzhi Yu, Yan Liu, Yupeng Zhang, Bo Lin, Shaojuan Li, Qiaoliang Bao
      Abstract: Shaojuan Li, Qiaoliang Bao, and co-workers review graphene optical biochemical sensors in article number 1603918. The true potential of graphene lies in optical sensors, especially for biochemical sensing in the diagnostics and health care sector. The working principle is based on whenever biomolecules come into contact with graphene, the Fermi level will shift either to p-type or n-type, changing its opto-electronic properties.
      PubDate: 2017-05-16T06:49:09.362952-05:
      DOI: 10.1002/adfm.201770118
       
  • Function Follows Form: Correlation between the Growth and Local Emission
           of Perovskite Structures and the Performance of Solar Cells
    • Authors: M. Ibrahim Dar; Alexander Hinderhofer, Gwenole Jacopin, Valentina Belova, Neha Arora, Shaik Mohammed Zakeeruddin, Frank Schreiber, Michael Grätzel
      Abstract: Understanding the relationship between the growth and local emission of hybrid perovskite structures and the performance of the devices based on them demands attention. This study investigates the local structural and emission features of CH3NH3PbI3, CH3NH3PbBr3, and CH(NH2)2PbBr3 perovskite films deposited under different yet optimized conditions using X-ray scattering and cathodoluminescence spectroscopy, respectively. X-ray scattering shows that a CH3NH3PbI3 film involving spin coating of CH3NH3I instead of dipping is composed of perovskite structures exhibiting a preferred orientation with [202] direction perpendicular to the surface plane. The device based on the CH3NH3PbI3 film composed of oriented crystals yields a relatively higher photovoltage. In the case of CH3NH3PbBr3, while the crystallinity decreases when the HBr solution is used in a single-step method, the photovoltage enhancement from 1.1 to 1.46 V seems largely stemming from the morphological improvements, i.e., a better connection between the crystallites due to a higher nucleation density. Furthermore, a high photovoltage of 1.47 V obtained from CH(NH2)2PbBr3 devices could be attributed to the formation of perovskite films displaying uniform cathodoluminescence emission. The comparative analysis of the local structural, morphological, and emission characteristics of the different perovskite films supports the higher photovoltage yielded by the relatively better performing devices.A comparative analysis of the local structural, morphological, and emission characteristics of different perovskite films rationally justifies the higher photovoltage yielded by the better performing devices.
      PubDate: 2017-05-16T06:11:18.217169-05:
      DOI: 10.1002/adfm.201701433
       
  • General Formation of Monodisperse IrM (M = Ni, Co, Fe) Bimetallic
           Nanoclusters as Bifunctional Electrocatalysts for Acidic Overall Water
           Splitting
    • Authors: Yecan Pi; Qi Shao, Pengtang Wang, Jun Guo, Xiaoqing Huang
      Abstract: The development of bifunctional electrocatalysts for overall water splitting in acidic media is vital for polymer electrolyte membrane (PEM) electrolyzers, but still full of obstacles. Here, highly efficient acidic overall water splitting is realized by utilizing ultrasmall, monodispersed Iridium (Ir)-based nanoclusters (NCs) as the candidate, via a surfactant-free, wet-chemical, and large-scalable strategy. Benefiting from the high specific surface area, clean surface, and strong binding between NCs and supports, the IrM NCs exhibit attractive activities and durability for both oxygen evolution reaction and hydrogen evolution reaction in acidic electrolytes, with IrNi NCs showing the best performance. More significantly, in the overall water splitting, IrNi NCs reach 10 mA cm−2 at a cell voltage of only 1.58 V in 0.5 m H2SO4 electrolyte, holding promises for potential implementation of PEM water electrolysis. This work opens a new avenue toward designing bifunctional “acidic stable” catalysts for efficient overall water splitting.Ir-based nanoclusters (NCs) with highly dispersive feature are synthesized using a wet-chemical large-scalable strategy. Benefiting from the clean surface, high surface-to-volume ratio, large proportion of surface atoms, as well as strong interaction with support, this new series of Ir-based NCs exhibit superior activity and enhanced durability as bifunctional electrocatalysts for overall water splitting in acidic electrolyte.
      PubDate: 2017-05-16T06:11:05.5903-05:00
      DOI: 10.1002/adfm.201700886
       
  • Deep-Blue Phosphorescent Ir(III) Complexes with Light-Harvesting
           Functional Moieties for Efficient Blue and White PhOLEDs in
           Solution-Process
    • Authors: Ganguri Sarada; Woosum Cho, Athithan Maheshwaran, Vijaya Gopalan Sree, Ho-Yeol Park, Yeong-Soon Gal, Myungkwan Song, Sung-Ho Jin
      Abstract: The photoluminescence (PL) efficiency of emitters is a key parameter to accomplish high electroluminescent performance in phosphorescent organic light-emitting diodes (PhOLEDs). With the aim of enhancing the PL efficiency, this study designs deep-blue emitting heteroleptic Ir(III) complexes (tBuCN-FIrpic, tBuCN-FIrpic-OXD, and tBuCN-FIrpic-mCP) for solution-processed PhOLEDs by covalently attaching the light-harvesting functional moieties (mCP-Me or OXD-Me) to the control Ir(III) complex, tBuCN-FIrpic. These Ir(III) complexes show similar deep-blue emission peaks around 453, 480 nm (298 K) and 447, 477 nm (77 K) in chloroform. tBuCN-FIrpic-mCP demonstrates higher light-harvesting efficiency (142%) than tBuCN-FIrpic-OXD (112%), relative to that of tBuCN-FIrpic (100%), due to an efficient intramolecular energy transfer from the mCP group to the Ir(III) complex. Accordingly, the monochromatic PhOLEDs of tBuCN-FIrpic-mCP show higher external quantum efficiency (EQE) of 18.2% with one of the best blue coordinates (0.14, 0.18) in solution-processing technology. Additionally, the two-component (deep-blue:yellow-orange), single emitting layer, white PhOLED of tBuCN-FIrpic-mCP shows a maximum EQE of 20.6% and superior color quality (color rendering index (CRI) = 78, Commission Internationale de L'Eclairage (CIE) coordinates of (0.353, 0.352)) compared with the control device containing sky-blue:yellow-orange emitters (CRI = 60, CIE coordinates of (0.293, 0.395)) due to the good spectral coverage by the deep-blue emitter.Highly efficient deep-blue phosphorescent Ir(III) complexes with light-harvesting groups are introduced for blue and white phosphorescent organic light-emitting diodes. Intramolecular energy transfer from a high triplet energy donor (mCP-Me) to the Ir(III) complex (tBuCN-FIrpic) is found to increase the photoluminescence efficiency of tBuCN-FIrpic-mCP. Therefore, tBuCN-FIrpic-mCP shows high external quantum efficiency of 18.2% with intense blue coordinates (0.142, 0.181) in a solution-process.
      PubDate: 2017-05-16T02:05:55.899905-05:
      DOI: 10.1002/adfm.201701002
       
  • Mo2C/CNT: An Efficient Catalyst for Rechargeable Li–CO2 Batteries
    • Authors: Yuyang Hou; Jiazhao Wang, Lili Liu, Yuqing Liu, Shulei Chou, Dongqi Shi, Huakun Liu, Yuping Wu, Weimin Zhang, Jun Chen
      Abstract: The rechargeable Li–CO2 battery is a novel and promising energy storage system with the capability of CO2 capture due to the reversible reaction between lithium ions and carbon dioxide. Carbon materials as the cathode, however, limit both the cycling performance and the energy efficiency of the rechargeable Li–CO2 battery, due to the insulating Li2CO3 formed in the discharge process, which is difficult to decompose in the charge process. Here, a Mo2C/carbon nanotube composite material is developed as the cathode for the rechargeable Li–CO2 battery and can achieve high energy efficiency (77%) and improved cycling performance (40 cycles). A related mechanism is proposed that Mo2C can stabilize the intermediate reduction product of CO2 on discharge, thus preventing the formation of insulating Li2CO3. In contrast to insulating Li2CO3, this amorphous Li2C2O4-Mo2C discharge product can be decomposed below 3.5 V on charge. The introduction of Mo2C provides an effective solution to the problem of low round-trip efficiency in the Li–CO2 battery.In a rechargeable Li–CO2 battery, molybdenum carbide/carbon nanotubes as a cathode can stabilize the intermediate product on discharge, by building a new chemical bond between Mo and O. This amorphous discharge product effectively prevents the formation of crystalline Li2CO3 and thereby reduces the potential plateau on charge and improves the round-trip efficiency of the rechargeable Li–CO2 battery.
      PubDate: 2017-05-16T02:05:51.654232-05:
      DOI: 10.1002/adfm.201700564
       
  • Photocatalytic Nanofiltration Membranes with Self-Cleaning Property for
           Wastewater Treatment
    • Authors: Yan Lv; Chao Zhang, Ai He, Shang-Jin Yang, Guang-Peng Wu, Seth B. Darling, Zhi-Kang Xu
      Abstract: Membrane fouling is one of the most severe problems restricting membrane separation technology for wastewater treatment. This work reports a photocatalytic nanofiltration membrane (NFM) with self-cleaning property fabricated using a facile biomimetic mineralization process. In this strategy, a polydopamine (PDA)/polyethyleneimine (PEI) intermediate layer is fabricated on an ultrafiltration membrane via a co-deposition method followed by mineralization of a photocatalytic layer consisting of β-FeOOH nanorods. The PDA–PEI layer acts both as a nanofiltration selective layer and an intermediate layer for anchoring the β-FeOOH nanorods via strong coordination complexes between Fe3+ and catechol groups. In visible light, the β-FeOOH layer exhibits efficient photocatalytic activity for degrading dyes through the photo-Fenton reaction in the presence of hydrogen peroxide, endowing the NFM concurrently with effective nanofiltration performance and self-cleaning capability. Moreover, the mineralized NFMs exhibit satisfactory stability under simultaneous filtration and photocatalysis processing, showing great potential in advanced wastewater treatment.A photocatalytic nanofiltration membrane (NFM) with self-cleaning capability is fabricated via a facile biomimetic mineralization process. In visible light, this membrane exhibits efficient photocatalytic activity for degrading dyes through the photo-Fenton reaction concurrently with effective nanofiltration performance. The as-prepared NFM shows great potential in advanced textile wastewater treatment with satisfactory stability.
      PubDate: 2017-05-16T02:05:43.274182-05:
      DOI: 10.1002/adfm.201700251
       
  • High-Performance Near-IR Photodetector Using Low-Bandgap
           MA0.5FA0.5Pb0.5Sn0.5I3 Perovskite
    • Authors: Xiaobao Xu; Chu-Chen Chueh, Peifeng Jing, Zhibin Yang, Xueliang Shi, Ting Zhao, Lih Y. Lin, Alex K.-Y. Jen
      Abstract: Photodetectors with ultrafast response are explored using inorganic/organic hybrid perovskites. High responsivity and fast optoelectronic response are achieved due to the exceptional semiconducting properties of perovskite materials. However, most of the perovskite-based photodetectors exploited to date are centered on Pb-based perovskites, which only afford spectral response across the visible spectrum. This study demonstrates a high-performance near-IR (NIR) photodetector using a stable low-bandgap Sn-containing perovskite, (CH3NH3)0.5(NH2CHNH2)0.5Pb0.5Sn0.5I3 (MA0.5FA0.5Pb0.5Sn0.5I3), which is processed with an antioxidant additive, ascorbic acid (AA). The addition of AA effectively strengthens the stability of Sn-containing perovskite against oxygen, thereby significantly inhibiting the leakage current. Consequently, the derived photodetector shows high responsivity with a detectivity of over 1012 Jones ranging from 800 to 970 nm. Such low-cost, solution processable NIR photodetectors with high performance show promising potential for future optoelectronic applications.A high-performance NIR photodetector derived from a stable low optical bandgap (Eg) Sn-containing perovskite, MA0.5FA0.5Pb0.5Sn0.5I3, is introduced. Ascorbic acid is used as an effective antioxidant additive to enhance the performance of the photodiode. Finally, a high detectivity of over 1012 Jones between 800 and 970 nm with a high response rate is achieved.
      PubDate: 2017-05-16T02:05:29.158953-05:
      DOI: 10.1002/adfm.201701053
       
  • Fully Stable and Homogeneous Lyotropic Liquid Crystal Alignment on
           Anisotropic Surfaces
    • Authors: Pim van der Asdonk; Peter J. Collings, Paul H. J. Kouwer
      Abstract: Lyotropic chromonic liquid crystals have great potential in both biosensing and optical devices due to their biocompatible nature and strong optical characteristics. These applications, however, demand a homogeneous and stable alignment on anisotropic surfaces, a challenge that, so far, has not been solved adequately. In this work, it is shown how to drastically increase the quality of in-plane alignment and stability of these liquid crystals on conventional rubbed polyimide substrates by the addition of a small amount of a nonionic surfactant. Samples with surfactant show excellent alignment that is stable for months, while control samples without surfactant show much poorer alignment that further deteriorates in days. Also, well-aligned dry films of chromonics can be prepared following this approach. It is demonstrated how to obtain high-quality alignment by controlling the concentration and the nature of the surfactant, in particular its molecular structure and hydrophilic/lipophilic balance (HLB value) and other critical parameters are discussed. It is believed that this approach may very well be essential for advancing the applicability of these water-based, biocompatible, and often highly dichroic materials for a wide range of uses.Taming the organization of chromonic lyotropic liquid crystals: Lyotropic chromonic liquid crystals combine the advantages of liquid crystals with biocompatibility, however, they prove difficult to align macroscopically. Using surfactants, it is shown how efficient and exceedingly stable alignment is realized. These results are crucial for application of this promising class of materials.
      PubDate: 2017-05-16T02:00:37.31528-05:0
      DOI: 10.1002/adfm.201701209
       
  • Molecular Design of Mesoporous NiCo2O4 and NiCo2S4 with
           Sub-Micrometer-Polyhedron Architectures for Efficient Pseudocapacitive
           Energy Storage
    • Authors: Yu Liu; Zhenbin Wang, Yijun Zhong, Moses Tade, Wei Zhou, Zongping Shao
      Abstract: Spinel-type NiCo2O4 (NCO) and NiCo2S4 (NCS) polyhedron architectures with sizes of 500–600 nm and rich mesopores with diameters of 1–2 nm are prepared facilely by the molecular design of Ni and Co into polyhedron-shaped zeolitic imidazolate frameworks as solid precursors. Both as-prepared NCO and NCS nanostructures exhibit excellent pseudocapacitance and stability as electrodes in supercapacitors. In particular, the exchange of O2− in the lattice of NCO with S2− obviously improves the electrochemical performance. NCS shows a highly attractive capacitance of 1296 F g−1 at a current density of 1 A g−1, ultrahigh rate capability with 93.2% capacitance retention at 10 A g−1, and excellent cycling stability with a capacitance retention of 94.5% after cycling at 1 A g−1 for 6000 times. The asymmetric supercapacitor with an NCS negative electrode and an active carbon positive electrode delivers a very attractive energy density of 44.8 Wh kg−1 at power density 794.5 W kg−1, and a favorable energy density of 37.7 Wh kg−1 is still achieved at a high power density of 7981.1 W kg−1. The specific mesoporous polyhedron architecture contributes significantly to the outstanding electrochemical performances of both NCO and NCS for capacitive energy storage.The successful synthesis of porous polyhedral-structured zeolitic imidazole framework–NiCo2O4 (ZIF–NCO) and zeolitic imidazole framework–NiCo2S4 (ZIF–NCS) nanoparticles by using a Ni and Co bimetallic zeolitic imidazolate framework as the solid precursors is reported. Both ZIF–NCO and ZIF–NCS exhibit excellent pseudocapacitance in the application of supercapacitors.
      PubDate: 2017-05-16T01:55:53.977189-05:
      DOI: 10.1002/adfm.201701229
       
  • pH-Triggered Pinpointed Cascading Charge-Conversion and Redox-Controlled
           Gene Release Design: Modularized Fabrication for Nonviral Gene
           Transfection
    • Authors: Qian Jiang; Yu Nie, Xiaobing Chen, Yiyan He, Dong Yue, Zhongwei Gu
      Abstract: Although pH and reduction responses are widely applied on gene and drug delivery system, the undefined molecule and disconnected response to corresponding transfection barriers still hamper their further application. Here, a multistage-responsive lipopeptides polycation-DNA nanoparticles (namely KR-DC) as gene vector is designed, consisting of three functional modules. It provides the following outstanding “smart” characteristics: i) facile manufacture and ease to adjust ingredients for different conditions, ii) negatively charged surface to remain stable and increase biocompatibility in physiological environment, iii) pH-triggered cascading charge-conversion corresponding to tumor extracellular pH and endo/lysosomal pH, iv) the first stage of charge reversal for uptake enhancement at tumor site, v) the second stage of charge conversion for rapid endosomal escape, vi) the third stage of redox degradation aiming at DNA controlled release and nuclear entry, vii) cell-penetrating peptides mimicking arginine-rich periphery targeting to membrane penetration capacity improvement, and viii) lipid forming hydrophobic cavity for potential fat-soluble drug encapsulation. Finally, KR-DC nanoparticles achieve significantly enhanced in vitro transfection efficiency by almost four orders of magnitude in manual tumor environment with reduced side effects and satisfying gene expression in Hela xenograft tumor model in vivo.Multistage-responsive lipopeptides polycation-DNA nanoparticles (KR-DC) are a new gene delivery system containing three functional modules, which are capable of pinpointed cascading charge-conversion triggered at tumor extracellular pH and endo/lysosomal pH and redox-controlled gene release, as well as having membrane penetration capacity. KR-DC nanoparticles achieve highly enhanced in vitro transfection efficiency and satisfying improved gene expression in vivo.
      PubDate: 2017-05-16T01:55:44.441391-05:
      DOI: 10.1002/adfm.201701571
       
  • Multianchored Glycoconjugate-Functionalized Magnetic Nanoparticles: A Tool
           for Selective Killing of Targeted Bacteria via Alternating Magnetic Fields
           
    • Authors: Yash S. Raval; Benjamin D. Fellows, Jamie Murbach, Yves Cordeau, Olin Thompson Mefford, Tzuen-Rong J. Tzeng
      Abstract: New technologies that do not rely on antibiotics are urgently needed to treat bacterial infections caused by multidrug-resistant bacteria. Herein, the feasibility of using alternating magnetic field (AMF) to selectively kill enterotoxigenic Escherichia coli strain K99 (EC K99) in the presence of multianchored glycoconjugate-functionalized magnetic nanoparticles is explored. Poly(ethylene oxide)-poly(acrylic acid)-dopamine functionalized magnetic nanoparticles (PEO-MNPs) are synthesized and functionalized with bacteria-specific glycoconjugate Neu5Ac(α2-3)-Gal-(β1-4)Glcβ-sp (GM3-MNPs) for specific adherence to EC K99. When such mixtures are exposed to an alternate magnetic field (31 kA m−1, 207 KHz), an ≈3-log reduction in colony forming units of EC K99 is achieved in 120 min. Moreover, in a mixed-bacterial culture environment, targeted killing of EC K99 is achieved with minimal damage to nontargeted bacterium. Electron microscopy images along with live/dead staining assays demonstrate visible membrane damage of EC K99 cells in the presence of GM3-MNPs and AMF. Additionally, intracellular adenosine triphosphate (ATP) levels of EC K99 are significantly diminished in the presence of GM3-MNPs and AMF. These results suggest that specific glycoconjugate-functionalized magnetic nanoparticles when mediated by AMF can be potentially used as a novel nonantibiotic treatment platform to inactivate/kill targeted bacterial pathogens, with minimal impact on normal microflora and the affected body region/tissue.Poly(ethylene oxide)-poly(acrylic acid)-dopamine functionalized magnetic nanoparticles (PEO-MNPs) are biofunctionalized with Neu5Ac(α2-3)-Gal-(β1-4)Glcβ-sp (GM3) molecule via a click chemistry route to produce PEO-MNPs functionalized with GM3 (GM3-MNPs). GM3-MNPs specifically interact with the Escherichia coli strain K99 (EC K99) and cause them to aggregate together. When such a nanoparticle–bacterial complex is exposed to alternating magnetic fields, ≈3-log reduction in the colony forming unit of EC K99 is observed.
      PubDate: 2017-05-15T12:20:44.499926-05:
      DOI: 10.1002/adfm.201701473
       
  • Few-Layered PtS2 Phototransistor on h-BN with High Gain
    • Authors: Liang Li; Weike Wang, Yang Chai, Huiqiao Li, Mingliang Tian, Tianyou Zhai
      Abstract: The very recently rediscovered group-10 transition metal dichalcogenides (TMDs) such as PtS2 and PtSe2, have joined the 2D material family as potentially promising candidates for electronic and optoeletronic applications due to their theoretically high carrier mobility, widely tunable bandgap, and ultrastability. Here, the first exploration of optoelectronic application based on few-layered PtS2 using h-BN as substrate is presented. The phototransistor exhibits high responsivity up to 1.56 × 103 A W−1 and detectivity of 2.9 × 1011 Jones. Additionally, an ultrahigh photogain ≈2 × 106 is obtained at a gate voltage Vg = 30 V, one of the highest gain among 2D photodetectors, which is attributed to the existence of trap states. More interestingly, the few-layered PtS2 phototransistor shows a back gate modulated photocurrent generation mechanism, that is, from the photoconductive effect dominant to photogating effect dominant via tuning the gate voltage from the OFF state to the ON state. Such good properties combined with gate-controlled photoresponse of PtS2 make it a competitive candidate for future 2D optoelectronic applications.A few-layered PtS2 phototransistor on h-BN with high gain is demonstrated. High responsivity up to 1.56 × 103 A W−1 and detectivity of 2.9 × 1011 Jones at a gate voltage Vg = 0 V are achieved. Moreover, the photocurrent generation mechanism can be tuned with the back gate from photoconductive effect dominant in the OFF state to photogating effect dominant in the ON state.
      PubDate: 2017-05-15T11:46:40.235465-05:
      DOI: 10.1002/adfm.201701011
       
  • DNA Lipoplex-Based Light-Harvesting Antennae
    • Authors: Sung Duk Jo; Jee Seon Kim, Inhye Kim, Jun Su Yun, Jae Chul Park, Bon Il Koo, Eunji Lee, Yoon Sung Nam
      Abstract: Natural light-harvesting complexes are operated through the well-designed self-assembly of pigments with large protein complexes in a thylakoid lipid bilayer. However, a long-range, directed transfer of excitation energy has not been achieved in artificial systems because the nanoscale arrangement of chromophores into stable micrometer-scale structures is highly challenging. Here the multiscale assembly of chromophores for excited energy transfer through the arrangement of chromophores on nanoscale DNA templates followed by their incorporation into larger multilamellar lipid structures is reported. Single-strand 10 nucleotide DNA molecules containing a terminal residue linked with three different chromophores are hybridized with their complementary 30 nucleotide matrix DNA strand. Due to the short DNA sequences, the energy transfer of the DNA-templated chromophore arrays is limited at 4 °C. However, the incorporation of DNA-templated chromophores into lipid-DNA complexes dramatically increases both of the efficiencies and antenna effects of the single and two-step energy transfers at room temperature through the structural stabilization and the secondary assembly of DNA between the interstitial spaces of multilamellar lipid structures. The findings suggest that the supramolecular alignment of DNA-templated chromophores, which has never been explored previously, can be a very promising route toward directed, long-range light harvesting.A Förster-type resonance energy transfer-based light-harvesting antenna is constructed through the supramolecular alignment of DNA-templated chromophores into the interstitial spaces of multilamellar lipid-DNA complexes (lipoplexes) via electrostatic interactions. Multiscale assembly of chromophores in 3D lipoplexes enables a dramatic increase in the efficiency and antenna effects of one- and two-step energy transfers.
      PubDate: 2017-05-15T11:46:28.025674-05:
      DOI: 10.1002/adfm.201700212
       
  • Understanding the Capacitance of PEDOT:PSS
    • Authors: Anton V. Volkov; Kosala Wijeratne, Evangelia Mitraka, Ujwala Ail, Dan Zhao, Klas Tybrandt, Jens Wenzel Andreasen, Magnus Berggren, Xavier Crispin, Igor V. Zozoulenko
      Abstract: Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is the most studied and explored mixed ion-electron conducting polymer system. PEDOT:PSS is commonly included as an electroactive conductor in various organic devices, e.g., supercapacitors, displays, transistors, and energy-converters. In spite of its long-term use as a material for storage and transport of charges, the fundamentals of its bulk capacitance remain poorly understood. Generally, charge storage in supercapacitors is due to formation of electrical double layers or redox reactions, and it is widely accepted that PEDOT:PSS belongs to the latter category. Herein, experimental evidence and theoretical modeling results are reported that significantly depart from this commonly accepted picture. By applying a two-phase, 2D modeling approach it is demonstrated that the major contribution to the capacitance of the two-phase PEDOT:PSS originates from electrical double layers formed along the interfaces between nanoscaled PEDOT-rich and PSS-rich interconnected grains that comprises two phases of the bulk of PEDOT:PSS. This new insight paves a way for designing materials and devices, based on mixed ion-electron conductors, with improved performance.By performing 2D Nernst–Planck–Poisson modeling of experimental cyclic voltammograms it is shown that (poly(3,4-ethylenedioxythiophene):polystyrene sulfonate) (PEDOT:PSS) capacitance originates from charging of double layers formed on boundaries between the two phases consisting of PEDOT-rich and PSS-rich grains.
      PubDate: 2017-05-15T11:46:23.245228-05:
      DOI: 10.1002/adfm.201700329
       
  • A Band-Edge Potential Gradient Heterostructure to Enhance Electron
           Extraction Efficiency of the Electron Transport Layer in High-Performance
           Perovskite Solar Cells
    • Authors: Yu Hou; Xiao Chen, Shuang Yang, Chunzhong Li, Huijun Zhao, Hua Gui Yang
      Abstract: As the key component in efficient perovskite solar cells, the electron transport layer (ETL) can selectively collect photogenerated charge carriers produced in perovskite absorbers and prevent the recombination of carriers at interfaces, thus ensuring a high power conversion efficiency. Compared with the conventional single- or dual-layered ETLs, a gradient heterojunction (GHJ) strategy is more attractive to facilitate charge separation because the potential gradient created at an appropriately structured heterojunction can act as a driving force to regulate the electron transport toward a desired direction. Here, a SnO2/TiO2 GHJ interlayer configuration inside the ETL is reported to simultaneously achieve effective extraction and efficient transport of photoelectrons. With such an interlayer configuration, the GHJs formed at the perovskite/ETL interface act collectively to extract photogenerated electrons from the perovskite layer, while GHJs formed at the boundaries of the interconnected SnO2 and TiO2 networks throughout the entire ETL layer can extract electron from the slow electron mobility TiO2 network to the high electron mobility SnO2 network. Devices based on GHJ ETL exhibit a champion power conversion efficiency of 18.08%, which is significantly higher than that obtained from the compact TiO2 ETL constructed under the comparable conditions.A gradient heterojunction electron transport layer (GHJ ETL), prepared by a facile low-temperature route, is utilized in perovskite solar cells (PSCs) for the first time. PSCs based on the potential GHJ ETL demonstrate an efficiency of 18.08% with less hysteresis effect, which is due to excellent management of charge transport and recombination.
      PubDate: 2017-05-15T11:46:18.586768-05:
      DOI: 10.1002/adfm.201700878
       
  • Multi-Atomic Layers of Metallic Aluminum for Ultralong Life Lithium
           Storage with High Volumetric Capacity
    • Authors: Jianan Gu; Bin Li, Zhiguo Du, Chao Zhang, Di Zhang, Shubin Yang
      Abstract: Metallic aluminum (Al) have been explored as potential anode materials for lithium storage because of its high theoretical capacity (993 mAh g–1) and low voltage plateaus. Al possesses high electric conductivity, low cost and environmental friendliness. Unfortunately, Al suffers from huge volume change (>100%) during the lithiation/delithiation process, which inevitably results in the pulverization of electrode and rapid capacity decay during cycling processes. To circumvent above issues, a simple but efficient strategy is demonstrated to fabricate free-standing multi-atomic layers of metallic Al by harnessing the good ductility of Al under pressure. The resultant multi-atomic Al layers are ultrathin, ≈3 nm, and have a large aspect ratio. Such unique features enable multi-atomic Al nanosheets to construct uniform and compact films with graphene. Thus, the hybrid films with different ratios are achieved, in which the notorious volume change of metallic Al can be efficiently circumvented via the good flexibility of graphene, and the density of whole electrode can be significantly enhanced. As a consequence, the optimized multi-atomic Al layers-graphene (AlL-G) film exhibits a very high volumetric capacity of 1089 mAh cm–3, high-rate capability and ultralong cycle life up to 20 000 cycles for lithium storage.Multi-atomic layers of metallic aluminum (Al) are successfully fabricated using a rolling method under high pressure. These ultrathin Al nanosheets could construct uniform films with graphene. The volume change of metallic Al can be alleviated via the flexibility of graphene, leading to a novel lithium-ion battery anode with high volumetric capacity, high-rate capability, and ultralong cyclic life up to 20 000 cycles.
      PubDate: 2017-05-15T11:46:13.947937-05:
      DOI: 10.1002/adfm.201700840
       
  • Tuning Unique Peapod-Like Co(SxSe1–x)2 Nanoparticles for Efficient
           Overall Water Splitting
    • Authors: Ling Fang; Wenxiang Li, Yongxin Guan, Yangyang Feng, Huijuan Zhang, Shilong Wang, Yu Wang
      Abstract: The development of efficient electrocatalysts with low cost and earth abundance for overall water splitting is very important in energy conversion. Although many electrocatalysts based on transition metal dichalcogenides have been developed, rational design and controllable synthesis of fine nanostructures with subtle morphologies and sequential chemical compositions related to these materials remains a challenge. This study reports a series of peapod-like composites with component-controllable Co(SxSe1–x)2 nanoparticles encapsulated in carbon fibers, which are obtained by using Co(CO3)0.5(OH)·0.11H2O nanowires as a precursor followed by coating carbon fiber and an adjustable sulfuration/selenylation process. Due to its increased exposure of active sites and improved charge and mass transport capability derived from the unique structure and morphology, the Co(SxSe1–x)2 samples display favorable catalytic activities. It is found that Co(S0.71Se0.29)2 exhibits the best hydrogen evolution reaction (HER) performance and Co(S0.22Se0.78)2 shows the highest activity for the oxygen evolution reaction (OER). When using Co(S0.71Se0.29)2 as a cathode and Co(S0.22Se0.78)2 as an anode, it demonstrates a durable activity for overall water splitting to deliver 10 mA cm−2 at a cell voltage of 1.63 V, thus offering an attractive cost-effective earth abundant material system toward water splitting.A series of peapod-like composites with component-controllable Co(SxSe1–x)2 nanoparticles encapsulated in carbon fibers are fabricated using Co(CO3)0.5(OH)·0.11H2O nanowires as a precursor followed by coating carbon fiber and an adjustable sulfuration/selenylation process. The optimized Co(S0.71Se0.29)2 Co(S0.22Se0.78)2 demonstrates a durable catalytic activity for overall water splitting.
      PubDate: 2017-05-15T11:46:08.692159-05:
      DOI: 10.1002/adfm.201701008
       
  • Improved Interfacial Floatability of Superhydrophobic/Superhydrophilic
           Janus Sheet Inspired by Lotus Leaf
    • Authors: Yuyan Zhao; Cunming Yu, Hao Lan, Moyuan Cao, Lei Jiang
      Abstract: Interfacial materials exhibiting superwettability have emerged as important tools for solving the real-world issues, such as oil-spill cleanup, fog harvesting, etc. The Janus superwettability of lotus leaf inspires the design of asymmetric interface materials using the superhydrophobic/superhydrophilic binary cooperative strategy. Here, the presented Janus copper sheet, composed of a superhydrophobic upper surface and a superhydrophilic lower surface, is able to be steadily fixed at the air/water interfaces, showing improved interfacial floatability. Compared with the floatable superhydrophobic substrate, the Janus sheet not only floats on but also attaches to the air–water interface. Similar results on Janus sheet are discovered at other multiphase interfaces such as hexane/water and water/CCl4 interfaces. In accordance with the improved stability and antirotation property, the microboat constructed by a Janus sheet shows the reliable navigating ability even under turbulent water flow. This contribution should unlock more functions of Janus interface materials, and extend the application scope of the binary cooperative materials system with superwettability.Inspired by the cooperative superwettability of a lotus leaf, it is demonstrated that a Janus sheet exhibiting versatile wettability can be stably fixed at multiphase interfaces. Based on the superhydrophobic/superhydrophilic binary cooperative effect, the Janus sheet floats on and tightly adheres to the interfaces.
      PubDate: 2017-05-15T11:46:02.475221-05:
      DOI: 10.1002/adfm.201701466
       
  • Flexible and Stretchable 3ω Sensors for Thermal Characterization of
           Human Skin
    • Authors: Limei Tian; Yuhang Li, Richard Chad Webb, Siddharth Krishnan, Zuguang Bian, Jizhou Song, Xin Ning, Kaitlyn Crawford, Jonas Kurniawan, Andrew Bonifas, Jun Ma, Yuhao Liu, Xu Xie, Jin Chen, Yuting Liu, Zhan Shi, Tianqi Wu, Rui Ning, Daizhen Li, Sanjiv Sinha, David G. Cahill, Yonggang Huang, John A. Rogers
      Abstract: Characterization of the thermal properties of the surface and subsurface structures of the skin can reveal the degree of hydration, the rate of blood flow in near-surface micro- and macrovasculature, and other important physiological information of relevance to dermatological and overall health status. Here, a soft, stretchable thermal sensor, based on the so-called three omega (i.e., 3ω) method, is introduced for accurate characterization of the thermal conductivity and diffusivity of materials systems, such as the skin, which can be challenging to measure using established techniques. Experiments on skin at different body locations and under different physical states demonstrate the possibilities. Systematic studies establish the underlying principles of operation in these unusual systems, thereby allowing rational design and use, through combined investigations based on analytical modeling, experimental measurements, and finite element analysis. The findings create broad opportunities for 3ω methods in biology, with utility ranging from the integration with surgical tools or implantable devices to noninvasive uses in clinical diagnostics and therapeutics.A soft, stretchable thermal sensor based on the three omega (i.e., 3ω) method enables accurate characterization of the thermal properties of diverse materials systems such as the human skin. Rational design of these sensors creates broad opportunities for 3ω methods in biology, with utility ranging from integration with surgical tools or implantable devices to noninvasive uses in clinical diagnostics and therapeutics.
      PubDate: 2017-05-15T11:45:57.572697-05:
      DOI: 10.1002/adfm.201701282
       
  • Improved Performance and Stability of All-Inorganic Perovskite
           Light-Emitting Diodes by Antisolvent Vapor Treatment
    • Authors: Chen Wu; Yatao Zou, Tian Wu, Muyang Ban, Vicenzo Pecunia, Yujie Han, Qipeng Liu, Tao Song, Steffen Duhm, Baoquan Sun
      Abstract: All-inorganic perovskite light-emitting diodes (LEDs) reveal efficient luminescence with high color purity, but their modest brightness and poor stability are still critical drawbacks. Here, the luminescent efficiency and the stability of perovskite LEDs (PeLEDs) are boosted by antisolvent vapor treatment of CsPbBr3 embedded in a dielectric polymer matrix of polyethylene oxide (PEO). A unique method is developed to obtain high quality CsPbBr3 emitting layers with low defects by controlling their grain sizes. CsPbBr3 in PEO matrix is post-treated with antisolvent of chloroform (CF), leading to microcrystals with a size of ≈5 µm along the in-plane direction with active emitting composite of 90%. A device based on CF post-treatment (CsPbBr3-PEO-CF) film displays a brightness of up to 51890 cd m−2 with an external quantum efficiency of 4.76%. CsPbBr3-PEO-CF PeLED still maintains 82% of its initial efficiency after 80 h continuous operation in ambient air, which indicates relatively good device stability. This work highlights that film quality is not only key to promoting fluorescence in CsPbBr3, but also to achieving higher performance PeLEDs.Antisolvent vapor treatment of CsPbBr3 films embedded in a dielectric polymer matrix film is proposed, resulting in microcrystal size of ≈5 µm with low defect density. A light-emitting diode based on composite CsPbBr3 films with this antisolvent vapor treatment displays a brightness of 51890 cd m−2 and an external quantum efficiency of 4.76%.
      PubDate: 2017-05-15T11:45:51.261297-05:
      DOI: 10.1002/adfm.201700338
       
  • Auxetic Foam-Based Contact-Mode Triboelectric Nanogenerator with Highly
           Sensitive Self-Powered Strain Sensing Capabilities to Monitor Human Body
           Movement
    • Authors: Steven L. Zhang; Ying-Chih Lai, Xu He, Ruiyuan Liu, Yunlong Zi, Zhong Lin Wang
      Abstract: The first contact-mode triboelectric self-powered strain sensor using an auxetic polyurethane foam, conductive fabric, and polytetrafluroethylene (PTFE) is fabricated. Utilizing the auxetic properties of the polyurethane foam, the auxetic polyurethane foam would expand into the PTFE when the foam is stretched, causing contact electrification. Due to a larger contact area between the PTFE and the foam as the foam is stretched, this device can serve effectively as a strain sensor. The sensitivity of this method is explored, and this sensor has the highest sensitivity in all triboelectric nanogenerator devices that are used previously as a strain sensor. Different applications of this strain sensor are shown, and this sensor can be used as a human body monitoring system, self-powered scale to measure weight, and a seat belt to measure body movements inside a car seat.The first contact-mode triboelectric self-powered strain sensor is fabricated using auxetic materials. Utilizing the auxetic properties of polyurethane foam, the polyurethane foam will expand when it is stretched, causing contact electrification. Different applications are realized and the triboelectric self-powered strain sensor can be used for monitoring human body movement.
      PubDate: 2017-05-15T01:20:33.459498-05:
      DOI: 10.1002/adfm.201606695
       
  • Coordinating Biointeraction and Bioreaction of a Nanocarrier Material and
           an Anticancer Drug to Overcome Membrane Rigidity and Target Mitochondria
           in Multidrug-Resistant Cancer Cells
    • Authors: Rui Xue Zhang; Lily Yi Li, Jason Li, Zhensong Xu, Azhar Z. Abbasi, Lucy Lin, Mohammad A. Amini, Wei Yu Weng, Yu Sun, Andrew M. Rauth, Xiao Yu Wu
      Abstract: Multidrug resistance (MDR) is a main cause of chemotherapy failure in cancer treatment. It is associated with complex cellular and molecular mechanisms including overexpression of drug efflux transporters, increased membrane rigidity, and impaired apoptosis. Numerous efforts have been made to overcome efflux transporter-mediated MDR using nanotechnology-based approaches. However, these approaches fail to surmount plasma membrane rigidity that attenuates drug penetration and nanoparticle endocytosis. Here, a “one-two punch” nanoparticle approach is proposed to coordinate intracellular biointeraction and bioreaction of a nanocarrier material docosahexaenoic acid (DHA) and an anticancer prodrug mitomycin C (MMC) to enhance mitochondrion-targeted toxicity. Incorporation of DHA in solid polymer-lipid nanoparticles first reduces the membrane rigidity in live cancer cells thereby increasing nanoparticle cellular uptake and MMC accumulation. Subsequent intracellular MMC bioreduction produces free radicals that in turn react with adjacent DHA inducing significantly elevated mitochondrial lipid peroxidation, leading to irreversible damage to mitochondria. Preferential tumor accumulation of the nanoparticles and the synergistic anticancer cytotoxicity remarkably inhibit tumor growth and prolonged host survival without any systemic toxicity in an orthotopic MDR breast tumor model. This work suggests that combinatorial use of biophysical and biochemical properties of nanocarrier materials with bioreactive prodrugs is a powerful approach to overcoming multifactorial MDR in cancer.A nanocomposite of binary lipids and polymer with anticancer prodrug mitomycin C (MMC) (MMC-DHA-PLN) is designed to overcome multifaceted drug resistance. It first utilizes the biointeraction of nanomaterial docosahexaenoic acid (DHA) to facilitate cellular uptake of the nanoparticle-encapsulated MMC, and then synchronizes intracellular activation of MMC and lipid peroxidation of DHA to damage mitochondria, leading to enhanced anticancer efficacy in vitro and in vivo.
      PubDate: 2017-05-12T07:22:26.15285-05:0
      DOI: 10.1002/adfm.201700804
       
  • Development and Translation of PEDOT:PSS Microelectrodes for
           Intraoperative Monitoring
    • Authors: Mehran Ganji; Erik Kaestner, John Hermiz, Nick Rogers, Atsunori Tanaka, Daniel Cleary, Sang Heon Lee, Jospeh Snider, Milan Halgren, Garth Rees Cosgrove, Bob S. Carter, David Barba, Ilke Uguz, George G. Malliaras, Sydney S. Cash, Vikash Gilja, Eric Halgren, Shadi A. Dayeh
      Abstract: Recording neural activity during neurosurgical interventions is an invaluable tool for both improving patient outcomes and advancing our understanding of neural mechanisms and organization. However, increasing clinical electrodes' signal-to-noise and spatial specificity requires overcoming substantial physical barriers due to the compromised metal electrochemical interface properties. The electrochemical properties of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) based interfaces surpass those of current clinical electrocorticography electrodes. Here, robust fabrication process of PEDOT:PSS microelectrode arrays is demonstrated for safe and high fidelity intraoperative monitoring of human brain. PEDOT:PSS microelectrodes measure significant differential neural modulation under various clinically relevant conditions. This study reports the first evoked (stimulus-locked) cognitive activity with changes in amplitude across pial surface distances as small as 400 µm, potentially enabling basic neurophysiology studies at the scale of neural micro-circuitry.The superiority of organic electrodes in mapping human brain activity under various clinical conditions is demonstrated. The improved electrode characteristics allow recording of changes in cognitive activity on the sub-millimeter scale. The great spatial specificity possible with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) microelectrodes and the reliable discrimination between and within language modalities underscore PEDOT:PSS's potential for standard electrocorticography clinical practice to maximize outcome for patient care.
      PubDate: 2017-05-12T07:22:09.985143-05:
      DOI: 10.1002/adfm.201700232
       
  • Porous Ti4O7 Particles with Interconnected-Pore Structure as a
           High-Efficiency Polysulfide Mediator for Lithium–Sulfur Batteries
    • Authors: Shilin Mei; Charl J. Jafta, Iver Lauermann, Qidi Ran, Martin Kärgell, Matthias Ballauff, Yan Lu
      Abstract: Multifunctional Ti4O7 particles with interconnected-pore structure are designed and synthesized using porous poly(styrene-b-2-vinylpyridine) particles as a template. The particles can work efficiently as a sulfur-host material for lithium–sulfur batteries. Specifically, the well-defined porous Ti4O7 particles exhibit interconnected pores in the interior and have a high-surface area of 592 m2 g−1; this shows the advantage of mesopores for encapsulating of sulfur and provides a polar surface for chemical binding with polysulfides to suppress their dissolution. Moreover, in order to improve the conductivity of the electrode, a thin layer of carbon is coated on the Ti4O7 surface without destroying its porous structure. The porous Ti4O7 and carbon-coated Ti4O7 particles show significantly improved electrochemical performances as cathode materials for Li–S batteries as compared with those of TiO2 particles.Ti4O7 particles and carbon-coated Ti4O7 particles with interconnected-pore structure are synthesized using porous poly(styrene-b-2-vinylpyridine) (PS-P2VP) particles as a template. The particles can work as a highly efficient polysulfide host for lithium–sulfur batteries by combining the advantage of mesopores for physical encapsulating of sulfur and a polar surface for chemical binding with polysulfides.
      PubDate: 2017-05-12T07:22:02.184174-05:
      DOI: 10.1002/adfm.201701176
       
  • Light-Fueled, Spatiotemporal Modulation of Mechanical Properties and Rapid
           Self-Healing of Graphene-Doped Supramolecular Elastomers
    • Authors: Manuel Noack; Rémi Merindol, Baolei Zhu, Alejandro Benitez, Sebastian Hackelbusch, Fabian Beckert, Sebastian Seiffert, Rolf Mülhaupt, Andreas Walther
      Abstract: Gaining spatially resolved control over the mechanical properties of materials in a remote, programmable, and fast-responding way is a great challenge toward the design of adaptive structural and functional materials. Reversible, temperature-sensitive systems, such as polymers equipped with supramolecular units, are a good model system to gain detailed information and target large-scale property changes by exploiting reversible crosslinking scenarios. Here, it is demonstrated that coassembled elastomers based on polyglycidols functionalized with complementary cyanuric acid and diaminotriazine hydrogen bonding couples can be remotely modulated in their mechanical properties by spatially confined laser irradiation after hybridization with small amounts of thermally reduced graphene oxide (TRGO). The TRGO provides an excellent photothermal effect, leads to light-adaptive steady-state temperatures, and allows local breakage/de-crosslinking of the hydrogen bonds. This enables fast self-healing and spatiotemporal modulation of mechanical properties, as demonstrated by digital image correlation. This study opens pathways toward light-fueled and light-adaptive graphene-based nanocomposites employing molecularly controlled thermal switches.Supramolecular polymer networks hybridized with thermally reduced graphene oxide allow for steady-state adaptation under continued irradiation. The graphene functions as an efficient photothermal converter and induces a thermoreversible de-crosslinking that can be spatially localized using lasers. This leads to large amplitude modulation of mechanical properties, and fast and efficient healing.
      PubDate: 2017-05-12T07:21:25.372853-05:
      DOI: 10.1002/adfm.201700767
       
  • Self-Contained Polymer/Metal 3D Printed Electrochemical Platform for
           Tailored Water Splitting
    • Authors: Adriano Ambrosi; Martin Pumera
      Abstract: The enormous advancements made recently in additive manufacturing require parallel development of new printable materials with particular focus on so-defined functional materials. Functional materials have specific properties that are useful for the fabrication of active devices such as sensors, electronic components, catalytic reactors, etc. It is shown here that the combination of standard 3D-printing technologies with easy-to-use electrochemical surface modification can facilitate the tuning of catalytic properties of printed metallic electrodes to be used as electrocatalysts for water splitting applications. A self-contained electrochemical system, consisting of electrodes and an electrochemical cell, is built via 3D metal and polymer printing. Stainless-steel electrodes are first obtained by selective laser melting additive manufacturing according to an established design; then electrochemical surface modification is performed to alter the electrode surface composition and therefore tune its catalytic properties toward the electrogeneration of hydrogen and oxygen. After surface characterization by means of scanning electron microscopy in combination with energy dispersive X-ray microanalysis to evaluate the efficiency of the electrochemical functionalization, electrochemical testing is carried out to evaluate the catalytic properties of the electrodes. A simple, proof-of-concept water electrolyzer is finally assembled with the best performing electrodes and tested in alkaline solution for water splitting capabilities.Tailoring catalytic properties of a water splitting electrolyzer using 3D-printing and electrochemical deposition methods is reported. A proof-of-concept water electrolyzer is assembled with the best-performing electrodes and tested in alkaline solution for water splitting capabilities.
      PubDate: 2017-05-12T07:16:33.721073-05:
      DOI: 10.1002/adfm.201700655
       
  • Humidity-Tolerant Single-Stranded DNA-Functionalized Graphene Probe for
           Medical Applications of Exhaled Breath Analysis
    • Authors: Youngmo Jung; Hi Gyu Moon, Chaehyun Lim, Keunsu Choi, Hyun Seok Song, Sukang Bae, Soo Min Kim, Minah Seo, Taikjin Lee, Seok Lee, Hyung-Ho Park, Seong Chan Jun, Chong-Yun Kang, Chulki Kim
      Abstract: Highly sensitive and selective chemiresistive sensors based on graphene functionalized by metals and metal oxides have attracted considerable attention in the fields of environmental monitoring and medical assessment because of their ultrasensitive gas detecting performance and cost-effective fabrication. However, their operation, in terms of detection limit and reliability, is limited in traditional applications because of ambient humidity. Here, the enhanced sensitivity and selectivity of single-stranded DNA-functionalized graphene (ssDNA-FG) sensors to NH3 and H2S vapors at high humidity are demonstrated and their sensing mechanism is suggested. It is found that depositing a layer of ssDNA molecules leads to effective modulation of carrier density in graphene, as a negative-potential gating agent and the formation of an additional ion conduction path for proton hopping in the layer of hydronium ions (H3O+) at high humidity (>80%). Considering that selectively responsive chemical vapors are biomarkers associated with human diseases, the obtained results strongly suggest that ssDNA-FG sensors can be the key to developing a high-performance exhaled breath analyzer for diagnosing halitosis and kidney disorder.ssDNA-functionalized graphene (FG) is utilized to investigate the H2S (biomarker: halitosis) and NH3 (biomarker: kidney disorder) sensing properties in high humidity conditions, which severely affect the device performance. In a high-humidity environment, the formation of H3O+ on the ssDNA-FG surface and the associated proton hopping play an important role in the enhanced sensing capability for high-performance exhaled breath analysis.
      PubDate: 2017-05-12T07:12:53.248063-05:
      DOI: 10.1002/adfm.201700068
       
  • Micropatterned Protein for Cell Adhesion through Phototriggered Charge
           Change in a Polyvinylpyrrolidone Hydrogel
    • Authors: Zunzhen Ming; Xing Ruan, Chunyan Bao, Qiuning Lin, Yi Yang, Linyong Zhu
      Abstract: Regulated immobilization of proteins on hydrogels allows for the creation of highly controlled microenvironments to meet the special requirements of cell biology and tissue engineering devices. Light is an ideal stimulus to regulate immobilization because it can be controlled in time, space, and intensity. Here, a photoresponsive hydrogel that enables the patterning of proteins by a combination of electrostatic adsorption and photoregulated charge change on a hydrogel is developed. It is based on a photosensitive cationic monomer (CLA), a coumarin caged lysine betaine zwitterion, incorporated into a polyvinylpyrrolidone (PVP) hydrogel, which can controllably change the charge from an adhesive positive state to an anti-adhesive zwitterion state upon irradiation at 365 nm. With this strategy, the immobilization of proteins is regulated and cell adhesion is programmed on hydrogels on demand. This approach should open up new avenues for hydrogels in biomedical applications.Using two bio-orthogonal interactions, electrostatic adsorption and photorelease, regulated protein and cell adhesion is accomplished on hydrogels. Combining light manipulation and mild electrostatic interactions allows the temporal, spatial, and dosage control of protein and cell adhesion to the hydrogel, which should allow for the use of hydrogels in biomedical applications.
      PubDate: 2017-05-12T07:12:42.039867-05:
      DOI: 10.1002/adfm.201606258
       
  • Extremely Strong and Transparent Chitin Films: A High-Efficiency,
           Energy-Saving, and “Green” Route Using an Aqueous KOH/Urea Solution
    • Authors: Junchao Huang; Yi Zhong, Lina Zhang, Jie Cai
      Abstract: Crystalline polysaccharides are useful for important and rapidly growing applications ranging from advanced energy storage, green electronics, and catalyst or enzyme supports to tissue engineering and biological devices. However, the potential value of chitin in such applications is currently neglected because of its poor swellability, reactivity, and solubility in most commonly used solvents. Here, a high-efficiency, energy-saving, and “green” route for the fabrication of extremely strong and transparent chitin films is described in which chitin is dissolved in an aqueous KOH/urea solution and neutralized in aqueous ethanol solution. The neutralization temperature, ethanol concentration, and chitin solution deacetylation time are critical parameters for the self-assembly of chitin chains and for tuning the morphology and aggregate structures of the resulting chitin hydrogels and films. Moreover, the drawing orientation can produce extremely strong and tough chitin films with a tensile strength, Young's modulus, and work of fracture of 226 MPa, 7.2 GPa, and 20.3 MJ m−3, respectively. The method developed here should contribute to the utilization of seafood waste and, thereby, to the sustainable use of marine resources.Extremely strong and transparent chitin films are prepared using a high-efficiency, energy-saving, and “green” route in which chitin is dissolved in an aqueous KOH/urea solution. The chitin films exhibit high strength and high toughness with a tensile strength, Young's modulus, and work of fracture of 226 MPa, 7.2 GPa, and 20.3 MJ m−3, respectively. This method should contribute to the development of sustainable marine resources.
      PubDate: 2017-05-11T07:26:12.362069-05:
      DOI: 10.1002/adfm.201701100
       
  • Self-Doping Cathode Interfacial Material Simultaneously Enabling High
           Electron Mobility and Powerful Work Function Tunability for
           High-Efficiency All-Solution-Processed Polymer Light-Emitting Diodes
    • Authors: Xiaojun Yin; Guohua Xie, Yuhao Peng, Bowen Wang, Tianhao Chen, Shuqi Li, Wenhao Zhang, Lei Wang, Chuluo Yang
      Abstract: A variety of N-hydrogenated/N-methylated pyridinium salts are elaborately designed and synthesized. Thermogravimetric and X-ray photoelectron spectra analysis indicate the intensities of the NH covalent bonds are strengthened step-by-step from 3,3′-(5′-(3-(pyridin-3-yl)phenyl)-[1,1′:3′,1″-terphenyl]-3,3″-diyl)dipyridine (Tm)-HCl to Tm-HBr and then Tm-TfOH, which results in gradually improved cathode interfacial modification abilities. The larger dipole moments of N+H containing moieties compared to those of the N+CH3 endow them with more preferable interfacial modification abilities. Electron paramagnetic resonance signals reveal the existence of radical anions in the solid state of Tm-TfOH, which enables its self-doping property and high electron mobility up to 1.67 × 10−3 cm2 V−1 s−1. Using the Tm-TfOH as the cathode interfacial layers (CILs), the phenyl-substituted poly(para-phenylene vinylene)-based all-solution-processed polymer light-emitting diodes (PLEDs) achieve more preferable device performances than the poly[(9,9-bis(3′-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)]-based ones, i.e., high current density of nearly 300 mA cm−2, very high luminance over 15 000 cd m−2 at a low bias of 5 V. Remarkably, the thickness of the CILs has little impact on the device performance and high efficiencies are maintained even at thicknesses up to 85 nm, which is barely realized in PLEDs with small-molecule-based electron transporting layers.A self-doping cathode interfacial material from diverse pyridinium salts enables high electron mobility and powerful work function tunability. The resulting all-solution-processed polymer light-emitting diodes achieve a very low driving voltage of 2.9 V at 1000 cd m−2, and high external quantum efficiency of 3.5% even in the thick films of cathode interfacial layer up to 85 nm.
      PubDate: 2017-05-11T07:25:49.042377-05:
      DOI: 10.1002/adfm.201700695
       
  • Ly6Chi Monocytes Delivering pH-Sensitive Micelle Loading Paclitaxel
           Improve Targeting Therapy of Metastatic Breast Cancer
    • Authors: Tianqun Lang; Xinyue Dong, Yan Huang, Wei Ran, Qi Yin, Pengcheng Zhang, Zhiwen Zhang, Haijun Yu, Yaping Li
      Abstract: Many immune cells are capable of homing to sites of disease and eradicating infections and abnormal cells. However, their efficacy is usually down-regulated in tumor microenvironments and it is difficult to boost. It is presumed that the anticancer activity of immune cells can be improved by integrating an additional therapeutic modality such as chemotherapy into the cells. Here, Ly6Chi monocytes armed with the paclitaxel (PTX)-loading pH-sensitive micelle (PM), termed as PM@MC, are prepared. The PM internalization does not significantly affect the properties of the host Ly6Chi monocytes. In the 4T1 metastatic breast cancer mice model, PM@MCs home to both primary tumor and the lung metastasis foci. PM@MC exhibit 15-fold higher intratumor PTX accumulation than the commercial PTX injection, and achieve a tumor inhibiting rate of 96.8% and a lung metastasis suppression rate of 99.2%. No significant change is recorded in histology of major organs and in hematological and biochemical parameters after PM@MC treatment. The pH-sensitive micelle/Ly6Chi monocyte drug delivery device thus has the application potential in the targeting therapy of breast cancer with metastasis.Paclitaxel (PTX)-loading pH-responsive micelle (PM)-loading Ly6Chi circulating monocytes (PM@MC) are constructed. PM@MC can be efficiently internalized by 4T1 cells, increasing the PTX amount in tumors and in the lungs. Considering that tumor-targeting behavior of PM@MC is independent of enhanced permeability and retention effect and heterogeneity of tumors, this can be an effective strategy for targeting therapy for metastatic breast cancer.
      PubDate: 2017-05-11T07:20:34.89181-05:0
      DOI: 10.1002/adfm.201701093
       
  • Modulating the Ferromagnet/Molecule Spin Hybridization Using an Artificial
           Magnetoelectric
    • Authors: Michał Studniarek; Salia Cherifi-Hertel, Etienne Urbain, Ufuk Halisdemir, Rémi Arras, Beata Taudul, Filip Schleicher, Marie Hervé, Charles-Henri Lambert, Abbass Hamadeh, Loïc Joly, Fabrice Scheurer, Guy Schmerber, Victor Da Costa, Bénédicte Warot-Fonrose, Cécile Marcelot, Olivia Mauguin, Ludovic Largeau, Florian Leduc, Fadi Choueikani, Edwige Otero, Wulf Wulfhekel, Jacek Arabski, Philippe Ohresser, Wolfgang Weber, Eric Beaurepaire, Samy Boukari, Martin Bowen
      Abstract: Spin-polarized charge transfer at the interface between a ferromagnetic (FM) metal and a molecule can lead to ferromagnetic coupling and to a high spin polarization at room temperature. The magnetic properties of these interfaces can not only alter those of the ferromagnet but can also stabilize molecular spin chains with interesting opportunities toward quantum computing. With the aim to enhance an organic spintronic device's functionality, external control over this spin polarization may thus be achieved by altering the ferromagnet/molecule interface's magnetic properties. To do so, the magnetoelectric properties of an underlying ferroelectric/ferromagnetic interface are utilized. Switching the ferroelectric polarization state of a PbZr0.2Ti0.8O3 (PZT) bottom layer within a PZT/Co/FePc-based (Pc - phthalocyanine) device alters the X-ray magnetic circular dichroism of the Fe site within the phthalocyanine molecular top layer. Thus, how to electrically alter the magnetic properties of an interface with high spin polarization at room temperature is demonstrated. This expands electrical control over spin-polarized FM/molecule interfaces, which is first demonstrated using ferroelectric molecules, to all molecular classes.The interface between a ferromagnetic metal (Co) and a molecule (Fe phthalocyanine) can exhibit high spin polarization at room temperature. To control the magnetic coupling that underscores this promising spintronic property, the magnetoelectric properties at the neighboring interface between an oxide ferroelectric (PZT) and Co are used. This enables electrical control over the spintronic properties of any ferromagnet/molecule interface.
      PubDate: 2017-05-10T06:56:03.393157-05:
      DOI: 10.1002/adfm.201700259
       
  • Dealloying in Individual Nanoparticles and Thin Film Grains: A Bragg
           Coherent Diffractive Imaging Study
    • Authors: Wonsuk Cha; Yihua Liu, Hoydoo You, Gregory Brian Stephenson, Andrew Ulvestad
      Abstract: Dealloying is a process whereby selective dissolution results in a porous, strained structure often with new properties. The process is of both intrinsic and applied interest, and recently has been used to make highly active catalysts. The porosity has been studied using electron microscopy while the dealloying-induced strain has been studied at the ensemble level using X-ray diffraction. Despite the importance of local, for example, at the individual particle or grain level, strain in controlling the properties of the dealloyed material, it remains unresolved due to the difficulty of imaging 3D strain distributions with nanometer resolution in reactive environments. This information could play an integral role in understanding and controlling lattice strain for a variety of applications. Here, 3D strain distributions in individual nanoparticles and thin film grains in silver–gold alloys undergoing nitric acid-induced dealloying are imaged by Bragg coherent diffractive imaging. Particles exhibit dramatic changes in their local strains due to dealloying but grains do not. The average lattice in both grains and particles contracts during dealloying. In general, the results reveal significant dealloying-induced strain heterogeneity at the nanoscale in both isolated and extended samples, which may be utilized to develop advanced nanostructures for a variety of important applications.The strain distribution in nanomaterials can significantly impact their properties. Using Bragg coherent diffractive imaging, the strain evolution due to dealloying in nanocrystals and grains is investigated. It is found that nanoparticles change their strain dramatically compared to their grain counterparts. These results have implications for strain tuning nanomaterials for a variety of applications.
      PubDate: 2017-05-09T06:01:31.157299-05:
      DOI: 10.1002/adfm.201700331
       
  • Sub-Micrometer Zeolite Films on Gold-Coated Silicon Wafers with
           Single-Crystal-Like Dielectric Constant and Elastic Modulus
    • Authors: Raffaele Tiriolo; Neel Rangnekar, Han Zhang, Meera Shete, Peng Bai, John Nelson, Evguenia Karapetrova, Christopher W. Macosko, Joern Ilja Siepmann, Ernesto Lamanna, Angelo Lavano, Michael Tsapatsis
      Abstract: A low-temperature synthesis coupled with mild activation produces zeolite films exhibiting low dielectric constant (low-k) matching the theoretically predicted and experimentally measured values for single crystals. This synthesis and activation method allows for the fabrication of a device consisting of a b-oriented film of the pure-silica zeolite MFI (silicalite-1) supported on a gold-coated silicon wafer. The zeolite seeds are assembled by a manual assembly process and subjected to optimized secondary growth conditions that do not cause corrosion of the gold underlayer, while strongly promoting in-plane growth. The traditional calcination process is replaced with a nonthermal photochemical activation to ensure preservation of an intact gold layer. The dielectric constant (k), obtained through measurement of electrical capacitance in a metal–insulator–metal configuration, highlights the ultralow k ≈ 1.7 of the synthetized films, which is among the lowest values reported for an MFI film. There is large improvement in elastic modulus of the film (E ≈ 54 GPa) over previous reports, potentially allowing for integration into silicon wafer processing technology.Well-intergrown and highly b-oriented silicalite-1 films on gold-coated silicon wafers are obtained. Optimized growth conditions and mild detemplation ensure compatibility with the support. The dielectric constant is measured by using a metal–insulator–metal configuration. For the first time, the films are found to combine ultralow dielectric constant and high mechanical strength, similar to the theoretically predicted values for single-crystal MFI.
      PubDate: 2017-05-08T08:15:39.142517-05:
      DOI: 10.1002/adfm.201700864
       
  • Nanostructures to Engineer 3D Neural-Interfaces: Directing Axonal
           Navigation toward Successful Bridging of Spinal Segments
    • Authors: Emily R. Aurand; Sadaf Usmani, Manuela Medelin, Denis Scaini, Susanna Bosi, Federica B. Rosselli, Sandro Donato, Giuliana Tromba, Maurizio Prato, Laura Ballerini
      Abstract: Neural interfaces are the core of prosthetic devices, such as implantable stimulating electrodes or brain–machine interfaces, and are increasingly designed for assisting rehabilitation and for promoting neural plasticity. Thus, beyond the classical neuroprosthetic concept of stimulating and/or recording devices, modern technology is pursuing toward ideal bio/electrode interfaces with improved adaptability to the brain tissue. Advances in material research are crucial in these efforts and new developments are drawing from engineering and neural interface technologies. Here, a microporous, self-standing, 3D interface made of polydimethylsiloxane (PDMS) implemented at the interfacing surfaces with novel conductive nanotopographies (carbon nanotubes) is exploited. The scaffold porosity is characterized by 3D X-ray microtomography. These structures are used to interface axons regenerated from cultured spinal explants and it is shown that engineering PDMS 3D interfaces with carbon nanotubes effectively changes the efficacy of regenerating fibers to target and reconnect segregated explant pairs. An improved electrophysiological performance is shown when the spinal tissue is interfaced to PDMS enriched by carbon nanotubes that may favor the use of our substrates as regenerative interfaces. The materials are implanted in the rat brain and a limited tissue reaction surrounding the implants at 2, 4, and 8 weeks from surgery is reported.A microporous, 3D interface made of polydimethylsiloxane implemented at the interfacing surfaces with novel conductive nanotopographies (carbon nanotubes) is created. Interfacing this structure to spinal explants changes the efficacy of regenerating fibers to reconnect segregated explant pairs. This 3D structure is tested for the first time in vivo and a limited brain reaction surrounding the implants is reported.
      PubDate: 2017-05-05T07:11:19.365296-05:
      DOI: 10.1002/adfm.201700550
       
  • Hard–Soft Composite Carbon as a Long-Cycling and High-Rate Anode for
           Potassium-Ion Batteries
    • Authors: Zelang Jian; Sooyeon Hwang, Zhifei Li, Alexandre S. Hernandez, Xingfeng Wang, Zhenyu Xing, Dong Su, Xiulei Ji
      Abstract: There exist tremendous needs for sustainable storage solutions for intermittent renewable energy sources, such as solar and wind energy. Thus, systems based on Earth-abundant elements deserve much attention. Potassium-ion batteries represent a promising candidate because of the abundance of potassium resources. As for the choices of anodes, graphite exhibits encouraging potassium-ion storage properties; however, it suffers limited rate capability and poor cycling stability. Here, nongraphitic carbons as K-ion anodes with sodium carboxymethyl cellulose as the binder are systematically investigated. Compared to hard carbon and soft carbon, a hard–soft composite carbon with 20 wt% soft carbon distributed in the matrix phase of hard carbon microspheres exhibits highly amenable performance: high capacity, high rate capability, and very stable long-term cycling. In contrast, pure hard carbon suffers limited rate capability, while the capacity of pure soft carbon fades more rapidly.The hard–soft composite carbon represents a highly promising anode material for practical applications of potassium-ion batteries. It exhibits a high reversible capacity of 261 mAh g−1, excellent rate capability, and stable cycling life of 200 cycles with capacity retention of 93%.
      PubDate: 2017-05-05T07:10:51.932601-05:
      DOI: 10.1002/adfm.201700324
       
  • A Cooperative Dimensional Strategy for Enhanced Nucleus-Targeted Delivery
           of Anticancer Drugs
    • Authors: Hebin Wang; Yang Li, Hongzhen Bai, Jie Shen, Xi Chen, Yuan Ping, Guping Tang
      Abstract: Although previous efforts have focused on altering the size of drug delivery carriers with the goal of improving the efficacy of anticancer therapy, the penetration of nuclear pores still represents a formidable barrier for the existing drug delivery systems. To this end, a cooperative, dimensional strategy is employed that can considerably improve intranuclear drug delivery to augment the overall therapeutic efficacy of therapeutics requiring nuclear entry. This cooperative strategy relies on i) the pH and redox responsiveness of micelles (termed PSPD) to extend blood circulation and increase both the cellular uptake and the redox sensitivity of PSPD to reduce micelles to a size that is more capable of nuclear entry and ii) a dexamethasone-conjugated micelle (termed Dex-P123) to target nuclei and dilate nuclear pores to allow PSPD to freely penetrate the nuclear pores. The resulting hybrid micelles, termed PSPD/Dex-P123, are found to deliver doxorubicin into cell nuclei more efficiently, thereby inducing more pronounced cytotoxicity against cancer cells in vitro. Importantly, a much more effective inhibition of tumor growth is observed in tumor-bearing mice, demonstrating the feasibility of this cooperative strategy for in vivo applications. The current study defines a useful dimensional strategy to improve nuclear-targeted and intranuclear drug delivery.Size switchable micelles with simultaneous nucleus targeting and nucleopore dilation abilities are prepared to enhance intranuclear delivery of anticancer drugs. The development of these micelles offers a cooperative, dimensional strategy that can considerably enhance nucleus-targeted drug delivery to augment the overall efficacy of therapeutics requiring nuclear entry.
      PubDate: 2017-05-04T06:21:42.237778-05:
      DOI: 10.1002/adfm.201700339
       
  • A Solid-State Fluorescent Material Based on Carbazole-Containing
           Difluoroboron β-Diketonate: Multiple Chromisms, the Self-Assembly
           Behavior, and Optical Waveguides
    • Authors: Peng-Zhong Chen; Han Zhang, Li-Ya Niu, Yi Zhang, Yu-Zhe Chen, Hong-Bing Fu, Qing-Zheng Yang
      Abstract: A carbazole-containing difluoroboron β-diketonate complex (BCZ), which shows strong fluorescence in both the solid state and in organic solutions, is reported. The crystalline materials of BCZ obtained from different solvents display different emission colors. Single-crystal analysis reveals that the enhanced overlap between adjacent molecules induces increased excited-state delocalization and is responsible for the variation of the emission colors from yellow to red. The emission colors of the materials are effectively tuned by external stimuli such as grinding, heating, and solvent vapor. The powder X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, and 1H NMR studies on materials of BCZ reveal that the thermochromic properties of BCZ are closely related to the removal of solvent molecules from the crystalline powders upon heating. Moreover, uniform 1D microstructures of BCZ obtained by solvent exchange in solution exhibit optical waveguide property with low optical loss.A solid-state fluorescent material based on carbazole-containing BF2bdk complex (BCZ) is reported. The emission colors of BCZ in solid state are dependent on its molecular packing modes and are successfully tuned upon external stimuli, such as grinding, heating, and solvent fuming. The uniform microrod of BCZ exhibits optical waveguide properties with low optical loss.
      PubDate: 2017-05-04T06:21:17.611173-05:
      DOI: 10.1002/adfm.201700332
       
  • Enhanced Capacitive Energy Storage in Polyoxometalate-Doped Polypyrrole
    • Authors: Sven Herrmann; Nihan Aydemir, Florian Nägele, Donato Fantauzzi, Timo Jacob, Jadranka Travas-Sejdic, Carsten Streb
      Abstract: High-performance batteries and supercapacitors require the molecular-level linkage of charge transport components and charge storage components. This study shows how redox-tunable Lindqvist-type molecular metal oxide anions [VnM6–nO19](2+n)− (M = W(VI) or Mo(VI); n = 0, 1, 2) can be incorporated in cationic polypyrrole (PPy) conductive polymer films by means of electrochemical polymerization. Electron microscopy and (spectro-)electrochemistry show that the electroactivity and morphology of the composites can be tuned by Lindqvist anion incorporation. Reductive electrochemical “activation” of the Lindqvist–PPy composites leads to significantly increased electrical capacitance (range: ≈25–38 F g−1, increase up to ≈25×), highlighting that this general synthetic route gives access to promising capacitive materials with suitable long-term stability. Electrochemical, electron microscopic, and Raman spectroscopic analyses together with density functional theory (DFT) calculations provide molecular-level insight into the effects of Lindqvist anion incorporation in PPy films and their role during reductive activation. The study therefore provides fundamental understanding of the principles governing the bottom-up integration of molecular components into nanostructured composites for electrochemical energy storage.Capacitive energy storage is explored in Lindqvist–polyoxometalate/polypyrrole composites. The specific capacitance can be significantly increased using a reductive activation protocol, leading to promising new materials for electrochemical energy storage.
      PubDate: 2017-05-04T06:21:02.429896-05:
      DOI: 10.1002/adfm.201700881
       
  • Engineering Large Anisotropic Magnetoresistance in La0.7Sr0.3MnO3 Films at
           Room Temperature
    • Authors: Paolo Perna; Davide Maccariello, Fernando Ajejas, Ruben Guerrero, Laurence Méchin, Stephane Flament, Jacobo Santamaria, Rodolfo Miranda, Julio Camarero
      Abstract: The magnetoresistance (MR) effect is widely used in technologies that pervade the world, from magnetic reading heads to sensors. Diverse contributions to MR, such as anisotropic, giant, tunnel, colossal, and spin-Hall, are revealed in materials depending on the specific system and measuring configuration. Half-metallic manganites hold promise for spintronic applications but the complexity of competing interactions has not permitted the understanding and control of their magnetotransport properties to enable the realization of their technological potential. This study reports on the ability to induce a dominant switchable magnetoresistance in La0.7Sr0.3MnO3 epitaxial films at room temperature (RT). By engineering an extrinsic magnetic anisotropy, a large enhancement of anisotropic magnetoresistance (AMR) is achieved which at RT leads to signal changes much larger than the other contributions such as the colossal magnetoresistance. The dominant extrinsic AMR exhibits large variation in the resistance in low field region, showing high sensitivity to applied low magnetic fields. These findings have a strong impact on the real applications of manganite-based devices for the high-resolution low field magnetic sensors or spintronics.A dominant switchable magnetoresistance, at room temperature, in half-metallic La0.7Sr0.3MnO3 epitaxial films is achieved by engineering an extrinsic magnetic anisotropy, through the use of substrates with progressively larger miscut angles. This leads to an enhancement of the anisotropic magnetoresistance (AMR) signal, much larger than the other contributions such as the colossal magnetoresistance (CMR), enabling the realization of the manganite technological potential.
      PubDate: 2017-05-04T06:20:34.737951-05:
      DOI: 10.1002/adfm.201700664
       
  • CuF2 as Reversible Cathode for Fluoride Ion Batteries
    • Authors: Duc Tho Thieu; Mohammed Hammad Fawey, Harshita Bhatia, Thomas Diemant, Venkata Sai Kiran Chakravadhanula, Rolf Jürgen Behm, Christian Kübel, Maximilian Fichtner
      Abstract: In the search for novel battery systems with high energy density and low cost, fluoride ion batteries have recently emerged as a further option to store electricity with very high volumetric energy densities. Among metal fluorides, CuF2 is an intriguing candidate for cathode materials due to its high specific capacity and high theoretical conversion potential. Here, the reversibility of CuF2 as a cathode material in the fluoride ion battery system employing a high F− conducting tysonite-type La0.9Ba0.1F2.9 as an electrolyte and a metallic La as an anode is investigated. For the first time, the reversible conversion mechanism of CuF2 with the corresponding variation in fluorine content is reported on the basis of X-ray photoelectron spectroscopy measurements and cathode/electrolyte interfacial studies by transmission electron microscopy. Investigation of the anode/electrolyte interface reveals structural variation upon cycling with the formation of intermediate layers consisting of i) hexagonal LaF3 and monoclinic La2O3 phases in the pristine interface; ii) two main phases of distorted orthorhombic LaF3 and monoclinic La2O3 after discharging; and iii) a tetragonal lanthanum oxyfluoride (LaOF) phase after charging. The fading mechanism of the cell capacity upon cycling can be explained by Cu diffusion into the electrolyte and side reactions due to the formation of the LaOF compound.The reversible conversion mechanism of CuF2 in novel fluoride ion battery system is reported. Investigation of the electrode/electrolyte interface reveals structural variation upon cycling. The fading mechanism of the CuF2/La0.9Ba0.1F2.9/La cell capacity upon cycling can be explained by Cu diffusion into the electrolyte and side reactions due to the formation of the lanthanum oxyfluoride compound.
      PubDate: 2017-05-04T06:16:34.613637-05:
      DOI: 10.1002/adfm.201701051
       
  • Anisotropy in Shape and Ligand-Conjugation of Hybrid Nanoparticulates
           Manipulates the Mode of Bio–Nano Interaction and Its Outcome
    • Authors: Xiaoyou Wang; Li Lin, Renfa Liu, Min Chen, Binlong Chen, Bo He, Bing He, Xiaolong Liang, Wenbing Dai, Hua Zhang, Xueqing Wang, Yiguang Wang, Zhifei Dai, Qiang Zhang
      Abstract: In an attempt to manipulate the biological features of nanomaterials via both anisotropic shape and ligand modification, four types of nanoparticulates with good morphological stability are designed and engineered, including hybrid nanospheres, nanodiscs, and nanodiscs with edge modification or plane modification of octa-arginine (R8) sequence. It is found that the R8 modification anisotropy can trigger huge differences in the endocytosis, intracellular trafficking, and even tissue penetration of nanoparticulates. From plane modification to edge modification of R8, the maximum increase in cell uptake is up to 17-fold, which is much more significant than shape anisotropy alone. On the other hand, six types of different cell lines are investigated to simulate biological microenvironment. It is demonstrated that the maximum difference in cell uptake among six cell lines is 12-fold. Three main driving forces are found to contribute to such bio–nano interactions. Based on the findings of this study, it seems possible to manipulate the biointeraction mode of nanomaterials and its output by regulating their anisotropy in both shape and ligand modification.Nanospheres, nanodiscs, and nanodiscs with edge modification or plane modification of octa-arginine sequence are prepared. From nanospheres to nanodiscs and from plane modification to edge modification, the cellular uptake increases 1.5- and 17-fold, respectively. Such alternations also affect the intracellular pathway and tumor penetration. The double effect of anisotropic shape and ligand-modification is significant and might be applied to manipulate the nanovector delivery.
      PubDate: 2017-05-04T06:16:10.142692-05:
      DOI: 10.1002/adfm.201700406
       
  • Synergistically Assembled Li2S/FWNTs@Reduced Graphene Oxide Nanobundle
           Forest for Free-Standing High-Performance Li2S Cathodes
    • Authors: Yan Chen; Songtao Lu, Jia Zhou, Wei Qin, Xiaohong Wu
      Abstract: Lithium sulfide (Li2S) has attracted increasing attention as a promising cathode because of its compatibility with more practical lithium-free anode materials and its high specific capacity. However, it is still a challenge to develop Li2S cathodes with low electrochemical overpotential, high capacity and reversibility, and good rate performance. This work designs and fabricates a practical Li2S cathode composed of Li2S/few-walled carbon nanotubes@reduced graphene oxide nanobundle forest (Li2S/FWNTs@rGO NBF). Hierarchical nanostructures are obtained by annealing the Li2SO4/FWNTs@GO NBF, which is prepared by a facile and scalable solution-based self-assembly method. Systematic characterizations reveal that in this unique NBF nanostructure, FWNTs act as axial shafts to direct the structure, Li2S serves as the internal active material, and GO sheets provide an external coating to minimize the direct contact of Li2S with the electrolyte. When used as a cathode, the Li2S/FWNTs@rGO NBF achieve a high capacity of 868 mAh g−1Li2S at 0.2C after 300 cycles and an outstanding rate performance of 433 mAh g−1Li2S even at 10C, suggesting that this Li2S cathode is a promising candidate for ultrafast charge/discharge applications. The design and synthetic strategies outlined here can be readily applied to the processing of other novel functional materials to obtain a much wider range of applications.Li2S/few-walled carbon nanotubes@reduced graphene oxide (Li2S/FWNTs@rGO) nanobundle forest with hierarchical nanostructure, in which FWNTs serve as axes, Li2S acts as stuffing, and rGO performs as shell coating, are synthesized using a facile, applicable, and synergistically assembled method. When used as a free-standing cathode, it achieves an excellent rate performance of 433 mAh g−1Li2S even at a high rate of 10C.
      PubDate: 2017-05-04T06:15:44.670563-05:
      DOI: 10.1002/adfm.201700987
       
  • Meso-Functionalization of Silk Fibroin by Upconversion Fluorescence and
           Near Infrared In Vivo Biosensing
    • Authors: Yang Song; Zaifu Lin, Lingqing Kong, Yao Xing, Naibo Lin, Zhisen Zhang, Bing-Hung Chen, Xiang-Yang Liu
      Abstract: In biomedical applications, it is very desirable to monitor the in vivo state of implanted devices, i.e., tracking the location, the state, and the interaction between the implanted devices and cell tissues. To achieve this goal, a generic strategy of soft materials meso-functionalization is presented. This is to acquire silk fibroin (SF) materials with added functions, i.e., in vivo bioimaging/sensing. The functionalization is by 3D materials assembly of functional components, lanthanide(Ln)-doped upconversion nanoparticles (UCNPs) on the mesoscopic scale to acquire upconversion fluorescent emission. To implement the meso-functionalization, the surfaces of UCNPs are modified by the hydroxyl groups (OH) from SiO2 or polyethylene glycol coating layers, which can interact with the carbonyl groups (CO) in SF scaffolds. The functionalized silk scaffolds are further implanted subcutaneously into mice, which allows the silk scaffolds to have fluorescent in vivo bioimaging and other biomedical functions. This material functionalization strategy may lead to the rational design of biomaterials in a more generic way.Bioimaging for silk fibroin scaffolds is achieved by the incorporation of surface-modified upconversion nanoparticles into the mesoscopic structure of silk fibroin materials via mesoscopic materials assembly. This allows real-time, non-invasive imaging in vivo.
      PubDate: 2017-05-03T06:25:49.678013-05:
      DOI: 10.1002/adfm.201700628
       
  • Cu Diffusion-Driven Dynamic Modulation of the Electrical Properties of
           Amorphous Oxide Semiconductors
    • Authors: Han-Wool Yeon; Janghyun Jo, Hochul Song, Youngho Kang, Sekwon Na, Hyobin Yoo, Seung-Yong Lee, Haelim Cho, Ho-Young Kang, Jung-Kyu Jung, Seungwu Han, Miyoung Kim, Young-Chang Joo
      Abstract: The exact role of Cu in the electrical properties of amorphous oxide semiconductors (AOSs) has been unclear, even though Cu has been the key element for the p-type characteristics of crystalline oxide semiconductors. Here, the dynamic changes, determined by diffusion kinetics, in the effect of Cu on the electrical properties of amorphous InGaZnO (a-IGZO) are revealed. In the early stage of annealing, Cu dominantly diffuses into a-IGZO through the free volume and acts as a mobile electron donor, which generates a resistive switching (RS) behavior related to the conductive filaments (CFs). With further annealing, substitutional Cu becomes predominant via In sites. After annealing, supersaturated Cu forms nonuniform, crystalline CuInO clusters in a-IGZO, which decrease the electrical conductivity of a-IGZO and deteriorate the CF-based RS performance. The findings reveal Cu diffusion mechanisms and the role of Cu in the electrical properties of AOSs dependent on the structural location and provide guidelines for modulating the RS characteristics of AOSs through Cu diffusion control.The effects of dynamic copper diffusion on the electrical properties of amorphous oxide semiconductors (AOSs) are investigated. As the dominant copper diffusion site is altered from the free volume to the substitutional sites as a function of the annealing conditions, the electrical conductivity and the resistive switching characterisitcs of AOSs are dynamically altered.
      PubDate: 2017-05-03T06:25:43.549069-05:
      DOI: 10.1002/adfm.201700336
       
  • Osmotic Pressure Triggered Rapid Release of Encapsulated Enzymes with
           Enhanced Activity
    • Authors: Weixia Zhang; Alireza Abbaspourrad, Dong Chen, Elizabeth Campbell, Hong Zhao, Yiwei Li, Qingning Li, David A. Weitz
      Abstract: In this study, a single-step microfluidic approach is reported for encapsulation of enzymes within microcapsules with ultrathin polymeric shell for controlled release triggered by an osmotic shock. Using a glass capillary microfluidic device, monodisperse water-in-oil-in-water double emulsion droplets are fabricated with enzymes in the core and an ultrathin middle oil layer that solidifies to produce a consolidated inert polymeric shell with a thickness of a few tens to hundreds of nanometers. Through careful design of microcapsule membranes, a high percentage of cargo release, over 90%, is achieved, which is triggered by osmotic shock when using poly(methyl methacrylate) as the shell material. Moreover, it is demonstrated that compared to free enzymes, the encapsulated enzyme activity is maintained well for as long as 47 days at room temperature. This study not only extends industrial applications of enzymes, but also offers new opportunities for encapsulation of a wide range of sensitive molecules and biomolecules that can be controllably released upon applying osmotic shock.Encapsulation of enzymes within microcapsules with an ultrathin shell is achieved through a single-step microfluidic process and is triggered released by an osmotic shock. By carefully choosing shell materials, over 90% of release ratio can be obtained. Moreover, the activity of encapsulated enzymes is well maintained for a long period.
      PubDate: 2017-05-03T06:25:36.391776-05:
      DOI: 10.1002/adfm.201700975
       
  • Injectable and Tunable Gelatin Hydrogels Enhance Stem Cell Retention and
           Improve Cutaneous Wound Healing
    • Authors: Yixiao Dong; Sigen A, Melanie Rodrigues, Xiaolin Li, Sun H. Kwon, Nina Kosaric, Sacha Khong, Yongsheng Gao, Wenxin Wang, Geoffrey C. Gurtner
      Abstract: Stem cells have shown substantial promise for various diseases in preclinical and clinical trials. However, low cell engraftment rates significantly limit the clinical translation of stem cell therapeutics. Numerous injectable hydrogels have been developed to enhance cell retention. Yet, the design of an ideal material with tunable properties that can mimic different tissue niches and regulate stem cell behaviors remains an unfulfilled promise. Here, an injectable poly(ethylene glycol) (PEG)–gelatin hydrogel is designed with highly tunable properties, from a multifunctional PEG-based hyperbranched polymer and a commercially available thiolated gelatin. Spontaneous gelation occurs within about 2 min under the physiological condition. Murine adipose-derived stem cells (ASCs) can be easily encapsulated into the hydrogel, which supports ASC growth and maintains their stemness. The hydrogel mechanical properties, biodegradability, and cellular responses can be finely controlled by changing hydrogel formulation and cell seeding densities. An animal study shows that the in situ formed hydrogel significantly improves cell retention, enhances angiogenesis, and accelerates wound closure using a murine wound healing model. These data suggest that injectable PEG–gelatin hydrogel can be used for regulating stem cell behaviors in 3D culture, delivering cells for wound healing and other tissue regeneration applications.An injectable poly(ethylene glycol) (PEG)–gelatin hydrogel is designed from a multifunctional PEG-based hyperbranched polymer and a commercially available thiolated gelatin. Spontaneous gelation occurs within 2 min under the physiological condition, with finely controlled hydrogel properties. The in situ formed hydrogel significantly improves cell retention, enhances angiogenesis, and accelerates wound closure in a murine wound model.
      PubDate: 2017-05-03T01:15:40.602267-05:
      DOI: 10.1002/adfm.201606619
       
  • Percolating Network of Ultrathin Gold Nanowires and Silver Nanowires
           toward “Invisible” Wearable Sensors for Detecting Emotional Expression
           and Apexcardiogram
    • Authors: My Duyen Ho; Yunzhi Ling, Lim Wei Yap, Yan Wang, Dashen Dong, Yunmeng Zhao, Wenlong Cheng
      Abstract: 2 nm thin gold nanowires (AuNWs) have extremely high aspect ratio (≈10 000) and are nanoscale soft building blocks; this is different from conventional silver nanowires (AgNWs), which are more rigid. Here, highly sensitive, stretchable, patchable, and transparent strain sensors are fabricated based on the hybrid films of soft/hard networks. They are mechanically stretchable, optically transparent, and electrically conductive and are fabricated using a simple and cost-effective solution process. The combination of soft and more rigid nanowires enables their use as high-performance strain sensors with the maximum gauge factor (GF) of ≈236 at low strain (
      PubDate: 2017-05-02T11:01:43.669437-05:
      DOI: 10.1002/adfm.201700845
       
  • A Charge Reversible Self-Delivery Chimeric Peptide with Cell
           Membrane-Targeting Properties for Enhanced Photodynamic Therapy
    • Authors: Li-Han Liu; Wen-Xiu Qiu, Yao-Hui Zhang, Bin Li, Chi Zhang, Fan Gao, Lu Zhang, Xian-Zheng Zhang
      Abstract: The cell membrane is the most important protective barrier in living cells and cell membrane targeted therapy may be a high-performance therapeutic modality for tumor treatment. Here, a novel charge reversible self-delivery chimeric peptide C16–PRP–DMA is developed for long-term cell membrane targeted photodynamic therapy (PDT). The self-assembled C16–PRP–DMA nanoparticles can effectively target to tumor by enhanced permeability and retention effect without additional carriers. After undergoing charge reverse in acidic tumor microenvironment, C16–PRP–DMA inserts into the tumor cell membrane with a long retention time of more than 14 h, which is very helpful for in vivo applications. It is found that under light irradiation, the reactive oxygen species generated by the inserted C16–PRP–DMA would directly disrupt cell membrane and rapidly induce cell necrosis, which remarkably increases the PDT effect in vitro and in vivo. This novel self-delivery chimeric peptide with a long-term cell membrane targeting property provides a new prospect for effective PDT of cancer.An easy-to-fabricate charge reversible self-delivery chimeric peptide is developed to realize cell membrane targeted photodynamic therapy (PDT). Under light irradiation, C16––PRP–DMA can directly disrupt the cell membrane and rapidly induce cell necrosis, which remarkably increases the PDT effect.
      PubDate: 2017-05-02T10:59:09.315007-05:
      DOI: 10.1002/adfm.201700220
       
  • Over 10% EQE Near-Infrared Electroluminescence Based on a Thermally
           Activated Delayed Fluorescence Emitter
    • Authors: Yi Yuan; Yun Hu, Ye-Xin Zhang, Jiu-Dong Lin, Ya-Kun Wang, Zuo-Quan Jiang, Liang-Sheng Liao, Shuit-Tong Lee
      Abstract: Significant effort has been made to develop novel material systems to improve the efficiency of near-infrared organic light-emitting diodes (NIR OLEDs). Of those, fluorescent chromophores are mostly studied because of their advantages in cost and tunability. However, it is still rare for fluorescent NIR emitters to present good color purities in the NIR range and to have high external quantum efficiency (EQE). Here, a wedge-shaped D-π-A-π-D emitter APDC-DTPA with thermally activated delayed fluorescence property and a small single-triplet splitting (ΔEst) of 0.14 eV is presented. The non-doped NIR device exhibits excellent performance with a maximum EQE of 2.19% and a peak wavelength of 777 nm. Remarkably, when 10 wt% of APDC-DTPA is doped in 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene host, an extremely high EQE of 10.19% with an emission peak of 693 nm is achieved. All these values represent the best result for NIR OLEDs based on a pure organic fluorescent emitter with similar device structure and color gamut.A near-infrared (NIR) thermally activated delayed fluorescence material, APDC-DTPA, containing acenaphtho[1,2-b]pyrazine-8,9-dicarbonitrile unit as acceptor and diphenylamine as donor unit is developed. A non-doped device based on APDC-DTPA exhibits a maximum external quantum efficiency (EQE) of 2.19% with an emission peak at 777 nm. A maximum EQE of up to 10.19% is achieved in a doped NIR device (λEL = 693 nm).
      PubDate: 2017-05-02T10:58:59.655347-05:
      DOI: 10.1002/adfm.201700986
       
  • Rugged Textile Electrodes for Wearable Devices Obtained by Vapor Coating
           Off-the-Shelf, Plain-Woven Fabrics
    • Authors: Lushuai Zhang; Marianne Fairbanks, Trisha L. Andrew
      Abstract: Fabrics are pliable, breathable, lightweight, ambient stable, and have unmatched haptic perception. Here, a vapor deposition method is used to transform off-the-shelf plain-woven fabrics, such as linen, silk, and bast fiber fabrics, into metal-free conducting electrodes. These fabric electrodes are resistant to wear, stable after laundering and ironing, and can be body-mounted with little detriment to their performance. A unique by-product of conformally vapor coating plain-woven fabrics is that textile parameters, such as thread material and fabric porosity, significantly affect the conductivity of the resulting fabric electrodes. The resistivities of the electrodes reported herein are linearly, not exponentially, dependent on length, meaning that they can be feasibly incorporated into garments and other large-area body-mounted devices. Further, these fabric electrodes possess the feel, weight, breathability, and pliability of standard fabrics, which are important to enable adoption of wearable devices.Vapor deposition is used to imperceptibly transform off-the-shelf plain-woven fabrics, such as linen, silk, and bast fiber fabrics, into metal-free conducting electrodes. The electrical conductivity of these electrodes remains unchanged upon bending, folding, and after laundering or ironing. These fabric electrodes also possess the feel, weight, breathability, and pliability of standard fabrics.
      PubDate: 2017-05-02T10:58:57.248468-05:
      DOI: 10.1002/adfm.201700415
       
  • A Versatile Method to Fabricate Highly In-Plane Aligned Conducting Polymer
           Films with Anisotropic Charge Transport and Thermoelectric Properties: The
           Key Role of Alkyl Side Chain Layers on the Doping Mechanism
    • Authors: Amer Hamidi-Sakr; Laure Biniek, Jean-Louis Bantignies, David Maurin, Laurent Herrmann, Nicolas Leclerc, Patrick Lévêque, Vishnu Vijayakumar, Nicolas Zimmermann, Martin Brinkmann
      Abstract: A general method is proposed to produce oriented and highly crystalline conducting polymer layers. It combines the controlled orientation/crystallization of polymer films by high-temperature rubbing with a soft-doping method based on spin-coating a solution of dopants in an orthogonal solvent. Doping rubbed films of regioregular poly(3-alkylthiophene)s and poly(2,5-bis(3-dodecylthiophen-2-yl)thieno[3,2-b]thiophene) with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) yields highly oriented conducting polymer films that display polarized UV–visible–near-infrared (NIR) absorption, anisotropy in charge transport, and thermoelectric properties. Transmission electron microscopy and polarized UV–vis–NIR spectroscopy help understand and clarify the structure of the films and the doping mechanism. F4TCNQ− anions are incorporated into the layers of side chains and orient with their long molecular axis perpendicular to the polymer chains. The ordering of dopant molecules depends closely on the length and packing of the alkyl side chains. Increasing the dopant concentration results in a continuous variation of unit cell parameters of the doped phase. The high orientation results in anisotropic charge conductivity (σ) and thermoelectric properties that are both enhanced in the direction of the polymer chains (σ = 22 ± 5 S cm−1 and S = 60 ± 2 µV K−1). The method of fabrication of such highly oriented conducting polymer films is versatile and is applicable to a large palette of semiconducting polymers.A versatile method is proposed to produce oriented and crystalline conducting polymer films. It combines alignment of semiconducting polymers by high-temperature rubbing with a soft-doping method. The oriented films show important anisotropy of UV–vis–near-infrared absorption, charge conductivity, and thermoelectric properties. The polymer side chain packing plays a key role on the intercalation of dopant molecules in the host polymer.
      PubDate: 2017-05-02T10:58:51.441282-05:
      DOI: 10.1002/adfm.201700173
       
  • Prestoring Lithium into Stable 3D Nickel Foam Host as Dendrite-Free
           Lithium Metal Anode
    • Authors: Shang-Sen Chi; Yongchang Liu, Wei-Li Song, Li-Zhen Fan, Qiang Zhang
      Abstract: Lithium metal is considered a “Holy Grail” of anode materials for high-energy-density batteries. However, both dendritic lithium deposition and infinity dimension change during long-term cycling have extremely restricted its practical applications for energy storage devices. Here, a thermal infusion strategy for prestoring lithium into a stable nickel foam host is demonstrated and a composite anode is achieved. In comparison with the bare lithium, the composite anode exhibits stable voltage profiles (200 mV at 5.0 mA cm−2) with a small hysteresis beyond 100 cycles in carbonate-based electrolyte, as well as high rate capability, significantly reduced interfacial resistance, and small polarization in a full-cell battery with Li4Ti5O12 or LiFePO4 as counter electrode. More importantly, in addition to the fact that lithium is successfully confined in the metallic nickel foam host, uniform lithium plating/stripping is achieved with a low dimension change (merely ≈3.1%) and effective inhibition of dendrite formation. The mechanism for uniform lithium stripping/plating behavior is explained based on a surface energy model.A Li–Ni composite anode is achieved via a thermal infusion strategy. It exhibits stable voltage profiles (90 mV at 1.0 mA cm−2) with small hysteresis beyond 100 cycles, as well as low dimension change and effective dendrite inhibition after 100 cycles in a symmetric cell.
      PubDate: 2017-05-02T10:58:39.767463-05:
      DOI: 10.1002/adfm.201700348
       
  • Solution-Processed Nanoporous Organic Semiconductor Thin Films: Toward
           Health and Environmental Monitoring of Volatile Markers
    • Authors: Fengjiao Zhang; Ge Qu, Erfan Mohammadi, Jianguo Mei, Ying Diao
      Abstract: Porous materials are ubiquitous in nature and have found a wide range of applications because of their unique absorption, optical, mechanical, and catalytic properties. Large surface-area-to-volume ratio is deemed a key factor contributing to their catalytic properties. Here, it is shown that introducing tunable nanopores (50–700 nm) to organic semiconductor thin films enhances their reactivity with volatile organic compounds by up to an order of magnitude, while the surface-area-to-volume ratio is almost unchanged. Mechanistic investigations show that nanopores grant direct access to the highly reactive sites otherwise buried in the conductive channel of the transistor. The high reactivity of nanoporous organic field-effect transistors leads to unprecedented ultrasensitive, ultrafast, selective chemical sensing below the 1 ppb level on a hundred millisecond time scale, enabling a wide range of health and environmental applications. Flexible sensor chip for monitoring breath ammonia is further demonstrated; this is a potential biomarker for chronic kidney disease.A generic method to solution process nanoporous thin films with pore sizes tunable from 50 to 700 nm for both the polymer and small molecule is demonstrated. The nanoporous transistors fabricated exhibit highly sensitive detection of volatile markers below 1 ppb on a hundred millisecond time scale. The nanopores function by exposing reactive sites in the conductive channel to the analytes.
      PubDate: 2017-05-02T10:58:18.987395-05:
      DOI: 10.1002/adfm.201701117
       
  • Maximized Effective Energy Output of Contact-Separation-Triggered
           Triboelectric Nanogenerators as Limited by Air Breakdown
    • Authors: Yunlong Zi; Changsheng Wu, Wenbo Ding, Zhong Lin Wang
      Abstract: Recent progress in triboelectric nanogenerators (TENGs) has demonstrated their promising potential as a high-efficiency mechanical energy harvesting technology, and plenty of effort has been devoted to improving the power output by maximizing the triboelectric surface charge density. However, due to high-voltage air breakdown, most of the enhanced surface charge density brought by material/surface optimization or external ion injection is not retainable or usable for electricity generation during the operation of contact-separation-triggered TENGs. Here, the existence of the air breakdown effect in a contact-separation mode TENG with a low threshold surface charge density of ≈40–50 µC m−2 is first validated under the high impedance external load, and then followed by the theoretical study of the maximized effective energy output as limited by air breakdown for contact-separation-triggered TENGs. The effects of air pressure and gas composition are also studied and propose promising solutions for reducing the air breakdown effect. This research provides a crucial fundamental study for TENG technology and its further development and applications.The air breakdown effect, as triggered by a contact-separation process, is systematically studied in triboelectric nanogenerators (TENGs) and effects of air pressure and gas composition are considered. This fundamental study of the maximum output of TENGs as limited by the air breakdown effect also provides strategies for further enhancement of output performance for highly efficient mechanical energy harvesting.
      PubDate: 2017-05-02T10:42:17.765544-05:
      DOI: 10.1002/adfm.201700049
       
  • Control of Polymorphism and Morphology in Solution Sheared Organic
           Field-Effect Transistors
    • Authors: Sergi Galindo; Adrián Tamayo, Francesca Leonardi, Marta Mas-Torrent
      Abstract: During the last decades, small molecule organic semiconductors have been successfully used as active layer in organic field-effect transistors (OFETs). Despite the high mobility achieved so far with organic molecules, in order to progress in the field it is crucial to find techniques to process them from solution. The device reproducibility is one of the principal weak points of organic electronics for further commercialization. To achieve a high device-to-device reproducibility it is essential to control the morphology and polymorphism of the active layer for OFET application. In this work, the preparation of thin films is reported based on blends of the organic semiconductor dibenzo-tetrathiafulvalene (DB-TTF) and polystyrene by a solution shearing technique compatible with upscaling. Here, it is demonstrated that varying the deposition parameters (i.e., speed and temperature) or the solution formulation (i.e., semiconductor/binder polymer ratio) is possible to control the film morphology and semiconductor polymorphism and, hence, the different intermolecular interactions. It is demonstrated that the control of the thermodynamics and kinetics of the crystallization process is key for the device performance optimization. Further, this is the first time that DB-TTF thin films of the α-polymorph are reported.Printed organic semiconductors require high control of polymorphism and morphology to enhance device reproducibility. Thin-film organic field-effect transistors have been prepared by solution shearing using blends of a small molecule semiconductor and a binder polymer. The deposition parameters and solution formulation determine the thin-film morphology and polymorphism, which, in turn, has a crucial impact on the device performance.
      PubDate: 2017-04-28T05:47:07.050435-05:
      DOI: 10.1002/adfm.201700526
       
  • Diels–Alder Reversible Thermoset 3D Printing: Isotropic Thermoset
           Polymers via Fused Filament Fabrication
    • Authors: Kejia Yang; Jesse C. Grant, Patrice Lamey, Alexandra Joshi-Imre, Benjamin R. Lund, Ronald A. Smaldone, Walter Voit
      Abstract: This study presents a new 3D printing process, the Diels–Alder reversible thermoset (DART) process, and a first generation of printable DART resins, which exhibit thermoset properties at use temperatures, ultralow melt viscosity at print temperatures, smooth part surface finish, and as-printed isotropic mechanical properties. This study utilizes dynamic covalent chemistry based on reversible furan-maleimide Diels–Alder linkages in the polymers, which can be decrosslinked and melt-processed during printing between 90 and 150 °C, and recrosslinked at lower temperatures to their entropically favored state. This study compares the first generation of DART materials to commonly 3D printed high-toughness thermoplastics. Parts printed from typical fused filament fabrication compatible materials exhibit anisotropy of more than 50% and sometimes upward of 98% in toughness when deformed along the build direction, while the first generation of DART materials exhibit less than 4% toughness reduction when deformed along the build direction. At room temperature, the toughest DART materials exhibit baseline toughness of 18.59 ± 0.91 and 18.36 ± 0.57 MJ m−3 perpendicular and parallel to the build direction, respectively. DART printing will enable chemists, polymer engineers, materials scientists, and industrial designers to translate new robust materials possessing targeted thermomechanical properties, multiaxial toughness, smooth surface finish, and low anisotropy.A new process called Diels–Alder reversible thermoset (DART) 3D printing, adapted from fused filament fabrication and based on dynamic, covalent chemistries, and a first generation of printable DART resins are demonstrated with thermoset properties at use temperatures up to 80 °C, superior surface finish, isotropism, and tough mechanical properties along the build direction of 18.36 ± 0.57 MJ m−3.
      PubDate: 2017-04-26T08:16:01.249537-05:
      DOI: 10.1002/adfm.201700318
       
  • Simultaneous Tenfold Brightness Enhancement and Emitted-Light Spectral
           Tunability in Transparent Ambipolar Organic Light-Emitting Transistor by
           Integration of High-k Photonic Crystal
    • Authors: Marco Natali; Santiago D. Quiroga, Luca Passoni, Luigino Criante, Emilia Benvenuti, Gabriele Bolognini, Laura Favaretto, Manuela Melucci, Michele Muccini, Francesco Scotognella, Fabio Di Fonzo, Stefano Toffanin
      Abstract: In organic light-emitting transistors, the structural properties such as the in-plane geometry and the lateral charge injection are the key elements that enable the monolithic integration of multiple electronic, optoelectronic, and photonic functions within the same device. Here, the realization of highly integrated multifunctional optoelectronic organic device is reported by introducing a high-capacitance photonic crystal as a gate dielectric into a transparent single-layer ambipolar organic light-emitting transistor (OLET). By engineering the photonic crystal multistack and bandgap, it is showed that the integration of the photonic structure has a twofold effect on the optoelectronic performance of the device, i.e., i) to modulate the spectral profile and outcoupling of the emitted light and ii) to enhance the transistor source–drain current by a 25-fold factor. Consequently, the photonic-crystal-integrated OLET shows an order of magnitude higher emitted power and brightness with respect to the corresponding polymer-dielectric device, while presenting as-designed electroluminescence spectral and spatial distribution. The results validate the efficacy of the proposed approach that is expected to unravel the technological potential for the realization of highly integrated optoelectronic smart systems based on organic light-emitting transistors.Monolithic integration of a high-k 1D photonic crystal as the gate dielectric in a transparent organic light-emitting transistor is reported. One order of magnitude enhancement of the emitted power in ambipolar conditions and as-predicted tunability in the spectral profile of the emitted light.
      PubDate: 2017-04-25T02:00:48.871026-05:
      DOI: 10.1002/adfm.201605164
       
  • Solid-State Hybrid Fibrous Supercapacitors Produced by Dead-End Tube
           Membrane Ultrafiltration
    • Authors: Yange Yu; Jing Zhong, Wei Sun, Rajesh Kumar, Nikhil Koratkar
      Abstract: The development of flexible supercapacitors with high volumetric performance is critically important for portable electronics applications, which are severely volume limited. Here, dead-end tube membrane (DETM) ultrafiltration is used to produce densely compacted carbon-nanotube/graphene fibrous films as solid-state supercapacitor electrodes. DETM is widely used in the water purification industry, but to date its use has not been explored for making supercapacitor electrode materials. Compared with vacuum-assisted filtration, dead-end filtration of the mixture through a porous membrane is carried out under much higher pressure, and thus the solvent can be gotten rid of much faster, with less energy consumption and in an environmentally friendly manner. More importantly, phase separation of the solid constituents in the mixture, due to concentration increase, can be suppressed in DETM. Therefore, highly uniform and densely compacted supercapacitor electrodes can be obtained with very high volumetric energy and power density. The volumetric energy density in this work (≈2.7 mWh cm-3) is at a higher level than all the all-solid-state fibrous supercapacitors reported to date. This can be attributed to the DETM process used, which produces a densely compacted network structure without compromising the availability of electrochemically active surface area.Dead-end tube membrane ultrafiltration is used to produce a dense compact network structure in which carbon nanotubes are well dispersed between graphene layers, thereby preventing restacking of the graphene sheets and maximizing the electrochemically active surface area of the electrode. This uniform and densely compacted electrode structure results in supercapacitors with very high volumetric energy density (≈2.7 mWh cm−3).
      PubDate: 2017-04-25T01:55:48.863533-05:
      DOI: 10.1002/adfm.201606461
       
  • Recent Advances in Sensing Applications of Two-Dimensional Transition
           Metal Dichalcogenide Nanosheets and Their Composites
    • Authors: Jianfeng Ping; Zhanxi Fan, Melinda Sindoro, Yibin Ying, Hua Zhang
      Abstract: Two-dimensional (2D) transition metal dichalcogenide (TMD) nanosheets, such as MoS2, WS2, etc., are attracting increasing interest due to their intriguing physical, chemical, electronic, and optical properties. Success in development of methods for large-scale production of 2D TMD nanosheets and their composites has given great potential for various novel applications. In this review, recent progress in sensing applications of 2D TMD nanosheets and their composites is introduced. Moreover, different sensing strategies and signal-transducing mechanisms for sensing devices based on 2D TMD nanosheets and their composites are also summarized and discussed.Two-dimensional layered transition metal dichalcogenide nanosheets have attracted extensive attention recently. Here, a comprehensive review on emerging applications of transition metal dichalcogenide nanosheets and their composites in sensing devices is presented, with a focus on signal transducing mechanisms and sensing strategies. Furthermore, current challenges and future prospects in this field are included to provide an overview of future research directions.
      PubDate: 2017-03-15T08:25:49.50559-05:0
      DOI: 10.1002/adfm.201605817
       
  • Controlled Electrochemical Deposition of Large-Area MoS2 on Graphene for
           High-Responsivity Photodetectors
    • Authors: Xi Wan; Kun Chen, Zefeng Chen, Fangyan Xie, Xiaoliang Zeng, Weiguang Xie, Jian Chen, Jianbin Xu
      Abstract: Controllable creating of wafer-scale homogeneous vertical or parallel 2D heterostructures with low cost by the van der Waals stacking or covalently bonded stitching of 2D layered materials, such as graphene, hexagonal boron nitride, and transition-metal dichalcogenides, is of great challenge. In this paper, a new green growth strategy for the fabrication of high-quality large-area and low-cost vertical MoS2/graphene heterostructures has been successfully demonstrated via electrochemical deposition in water solution, followed by an annealing process in chemical vapour deposition system for the first time. The vertical MoS2/graphene heterostructures have been systematically investigated by the combined use of Raman spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. This simple, reliable, and environmentally friendly growth strategy on conducting monolayer graphene in a controlled manner opens up a new way for producing low-cost, large-area, and high-quality vertical MoS2/graphene heterostructures, which have promising applications not only in electronics and optoelectronics but also in the fields of catalysis and renewable energy.Centimeter-size and homogeneous vertical MoS2/graphene heterostructures have been successfully fabricated in a controlled manner of thickness (5–150 nm) via environmentally friendly electrochemical deposition of MoS2 on conducting graphene electrodes in the aqueous solution of ammonium tetrathiomolybdate (NH4)2MoS4, followed by a vacuum annealing process in the atmosphere of Ar and H2 without additional sulfur.
      PubDate: 2017-01-11T05:20:50.195027-05:
      DOI: 10.1002/adfm.201603998
       
  • Epitaxial Stitching and Stacking Growth of Atomically Thin
           Transition-Metal Dichalcogenides (TMDCs) Heterojunctions
    • Authors: Kun Chen; Xi Wan, Jianbin Xu
      Abstract: In recent years, ultrathin two-dimensional (2D) transition metal dichalcogenides (TMDCs), such as MX2 (M = Mo, W; X = S, Se, etc.) have become the flagship materials after graphene. 2D-MX2 have attracted significant attention due to their novel properties arising from their strict dimensional confinement as well as strong spin–orbit coupling effects, which provides an ideal platform for exploring new fundamental research and realizing technological innovation. The 2D nature and the small lattice mismatch between MX2 make them ideal templates for construction of vertical and lateral heterojunctions at atomic scale by means of CVD epitaxial growth. This feature article aims to introduce current advances in the preparation of vertical or lateral epitaxial heterostructures based on 2D MX2 nanosheets as well as their potential applications in electronics, and optoelectronics. Firstly, various epitaxial CVD strategies for synthesis of vertical or lateral 2D MX2 heterostructures are comprehensively reviewed. Meanwhile, the advantages of these epitaxial methods as well as several applications of 2D MX2 heterostructures, such as photodiodes and photovoltaic devices are highlighted. Then the remaining challenges facing the controllable syntheses and the future perspectives of this promising area are discussed.Two-dimensional transition-metal dichalcogenide (2D TMDCs) heterojunctions offer new and exciting opportunities to fabricate novel devices with unprecedented performance. Currently, the chemical vapor deposition technique (CVD) has displayed great promise to prepare lateral or vertical epitaxial TMDCs heterostructures. An overview of recent progress in the epitaxial growth of heterojunctions on the basis of ultrathin TMDCs and their potential application is presented.
      PubDate: 2017-01-09T08:31:55.550487-05:
      DOI: 10.1002/adfm.201603884
       
  • Thermal Properties of Two Dimensional Layered Materials
    • Authors: Yuxi Wang; Ning Xu, Deyu Li, Jia Zhu
      Abstract: The rise of graphene has motivated intensive investigation into other two-dimensional layered materials (2DLMs). In addition to their superior optical, electrical, and mechanical properties, 2DLMs have also demonstrated intriguing thermal properties, the understanding of which is not only fundamentally important but also critical to enabling widespread applications in electronics, optoelectronics, and energy conversion and storage devices. Here, we review recent progress in the thermal transport of 2DLMs. Indeed, due to unique and diversified two dimensional crystal structures and the contribution of different phonon modes to thermal transport, while the family of 2DLMs share common thermal properties, such as layer-dependent thermal conductivity, each member also has unique features related to thermal transport. Ultimately, the unusual and rich thermal properties of two-dimensional materials can lay a solid foundation for understanding new phonon transport physics and potentially lead to novel applications in various emerging fields.Two dimensional layered materials (2DLMs) have shown unique thermal transport properties, such as anomalous size-dependent and anisotropic thermal conductivity. The recent progress in thermal property measurement (measurement methods and measurement results) for 2DLMs is reviewed and their potential applications in energy conversion and thermal management are also discussed.
      PubDate: 2017-01-06T08:31:00.147035-05:
      DOI: 10.1002/adfm.201604134
       
  • Layer-Number Dependent Optical Properties of 2D Materials and Their
           Application for Thickness Determination
    • Authors: Xiao-Li Li; Wen-Peng Han, Jiang-Bin Wu, Xiao-Fen Qiao, Jun Zhang, Ping-Heng Tan
      Abstract: The quantum confinement in atomic scale and the presence of interlayer coupling in multilayer make the electronic and optical properties of 2D materials (2DMs) be dependent on the layer number (N) from monolayer to multilayer. Optical properties of 2DMs have been widely probed by several optical techniques, such as optical contrast, Rayleigh scattering, Raman spectroscopy, optical absorption, photoluminescence, and second harmonic generation. Here, it is reviewed how optical properties of several typical 2DMs (e.g., monolayer and multilayer graphenes, transition metal dichalcogenides) probed by these optical techniques significantly depend on N. Further, it has been demonstrated how these optical techniques service as fast and nondestructive approaches for N counting or thickness determination of these typical 2DM flakes. The corresponding approaches can be extended to the whole 2DM family produced by micromechanical exfoliations, chemical-vapor-deposition growth, or transfer processes on various substrates, which bridges the gap between the characterization and international standardization for thickness determination of 2DM flakes.Optical properties of 2D materials, such as optical contrast, Rayleigh scattering, Raman spectroscopy, optical absorption, photoluminescence, and second harmonic generation, are dependent on the layer number. Here, we demonstrate how these optical techniques serve as fast and nondestructive approaches for layer number counting or thickness determination of these typical 2D material flakes.
      PubDate: 2017-01-05T04:26:00.735409-05:
      DOI: 10.1002/adfm.201604468
       
  • Analyzing the Carrier Mobility in Transition-Metal Dichalcogenide MoS2
           Field-Effect Transistors
    • Authors: Zhihao Yu; Zhun-Yong Ong, Songlin Li, Jian-Bin Xu, Gang Zhang, Yong-Wei Zhang, Yi Shi, Xinran Wang
      Abstract: Transition-metal dichalcogenides (TMDCs) are an important class of two-dimensional (2D) layered materials for electronic and optoelectronic applications, due to their ultimate body thickness, sizable and tunable bandgap, and decent theoretical room-temperature mobility. So far, however, all TMDCs show much lower mobility experimentally because of the collective effects by foreign impurities, which has become one of the most important limitations for their device applications. Here, taking MoS2 as an example, the key factors that bring down the mobility in TMDC transistors, including phonons, charged impurities, defects, and charge traps, are reviewed. A theoretical model that quantitatively captures the scaling of mobility with temperature, carrier density, and thickness is introduced. By fitting the available mobility data from literature over the past few years, one obtains the density of impurities and traps for a wide range of transistor structures. It shows that interface engineering can effectively reduce the impurities, leading to improved device performances. For few-layer TMDCs, the lopsided carrier distribution is analytically modeled to elucidate the experimental increase of mobility with the number of layers. From our analysis, it is clear that the charge transport in TMDC samples is a very complex problem that must be handled carefully.Transition-metal dichalcogenides (TMDCs) are widely investigated for enhanced characteristics for electronics among next generation semiconductors. The understanding of charge transport in TMDCs is significant for further device applications. Through carefully analyzing the reported high performance MoS2 devices, this review provides a systematic theoretical and experimental path to optimize the device structure and improve device performance.
      PubDate: 2017-01-03T09:15:51.577192-05:
      DOI: 10.1002/adfm.201604093
       
  • Ultrafast Laser Spectroscopy of Two-Dimensional Materials Beyond Graphene
    • Authors: Frank Ceballos; Hui Zhao
      Abstract: Starting with the discovery of graphene in 2004, the interest in two-dimensional materials since then has been exponentially growing. Across many disciplines, their exceptional electrical, chemical, thermal, and optical properties have drawn considerable attention that has created an entire field within a decade of their discovery. Driven by the mechanical exfoliation technique that allows for the quick exploration of these two-dimensional materials and their novel devices, joint efforts have been made in order to understand and exploit their potential, consequently leading to the development of their large-scale growth. This review focuses on recent studies using ultrafast laser spectroscopy that have revealed the photocarrier dynamics in two-dimensional materials and laid the foundation of their behavior. We provide a brief introduction on ultrafast laser spectroscopy, discuss several aspects of the photocarrier dynamics, and conclude with our perspective on future developments.Recent progress on using ultrafast lasers to study two-dimensional materials is reviewed. Fundamentals of pump–probe spectroscopy and the current understanding of various aspects of photocarrier dynamics, such as thermalization, energy relaxation, exciton formation, exciton–exciton annihilation, recombination, and transport, are discussed. Applications of ultrafast laser spectroscopy on studies of spin dynamics, coherent properties, and van der Waals heterostructures are also introduced.
      PubDate: 2016-12-21T03:20:50.094476-05:
      DOI: 10.1002/adfm.201604509
       
  • Electric Field Effect in Two-Dimensional Transition Metal Dichalcogenides
    • Authors: Fucai Liu; Jiadong Zhou, Chao Zhu, Zheng Liu
      Abstract: Two-dimensional (2D) materials have been an emerging platform for future device applications. Among them, 2D transition metal dichalcogenides (TMDs) have attracted substantial interest because of their fascinating properties ranging from semiconductor, semimetal, metal, to superconductor. The electric controllability over their physical properties is extremely important for their device application. This feature article presents recent progress in the electrical manipulation of the optical, electric, and spin/valley dependent properties of 2D TMDs. Also, some of the outstanding challenges and opportunities in this promising research field are highlighted.The outstanding electric, optical, and valleytronic properties of 2D transition metal dichalcogenides (TDMDs) make them promising for device applications, while the electric controllability is extremely important for demonstrating their device application. In this review, we highlight the recent progress on the electric controllability of 2D TMDs and provide the opportunities that need to be investigated.
      PubDate: 2016-12-20T05:11:00.908498-05:
      DOI: 10.1002/adfm.201602404
       
  • Doping, Contact and Interface Engineering of Two-Dimensional Layered
           Transition Metal Dichalcogenides Transistors
    • Authors: Yuda Zhao; Kang Xu, Feng Pan, Changjian Zhou, Feichi Zhou, Yang Chai
      Abstract: Owing to an ultrathin body, atomic scale smoothness, dangling bond-free surface, and sizable bandgap, transistors based on two-dimensional (2D) layered semiconductors show the potential of scalability down to the nanoscale, high-density three-dimensional integration, and superior performance in terms of better electrostatic control and smaller power consumption compared with conventional three-dimensional semiconductors (Si, Ge, and III-V compound materials). To apply 2D layered materials into complementary metal-oxide-semiconductor logic circuits, it is important to modulate the carrier type and density in a controllable manner, and engineer the contact (between metal electrode and 2D semiconductor) and the interface (between dielectrics and semiconducting channel) to get close to their intrinsic carrier mobility. In this review, the most widely studied 2D transition metal dichalcogenides (TMD) are focused on, and an overview of recent progress on doping, contact, and interface engineering of the TMD-based field-effect transistors is provided.Field-effect transistors based on two-dimensional transition metal dichalcogenides (TMDs) show the potential for next-generation electronic devices. Here, the state-of-the-art methods to control the carrier type, engineer the metal/TMDs contact, and optimize the dielectric/TMDs interface are reviewed.
      PubDate: 2016-12-07T08:02:14.360874-05:
      DOI: 10.1002/adfm.201603484
       
  • Ultrafine Graphene Nanomesh with Large On/Off Ratio for High-Performance
           Flexible Biosensors
    • Authors: Yanbing Yang; Xiangdong Yang, Xuming Zou, Shiting Wu, Da Wan, Anyuan Cao, Lei Liao, Quan Yuan, Xiangfeng Duan
      Abstract: Graphene is an attractive material for flexible electronics and biosensors, yet its zero bandgap nature has limited the on/off ratio of field-effect transistors (FETs) and the sensitivity of biosensors based on graphene. Graphene nanomesh (GNM), a continuous 2D graphene nanostructure with a high density of holes punched in the basal plane, has been created to introduce lateral confinement and enable improved on/off ratio. However, the GNMs produced to date typically have a relatively large dimension (constriction neck width>5 nm) and low on/off ratio (≈100) limited by the resolution of the lithography process used. Here, the exploration of a directly grown mesoporous silica template is reported for the preparation of ultrafine GNMs with considerably narrower neck width (
      PubDate: 2016-12-02T12:09:58.946884-05:
      DOI: 10.1002/adfm.201604096
       
  • The Roadmap of Graphene-Based Optical Biochemical Sensors
    • Authors: Bannur Nanjunda Shivananju; Wenzhi Yu, Yan Liu, Yupeng Zhang, Bo Lin, Shaojuan Li, Qiaoliang Bao
      Abstract: Graphene is a novel two-dimensional material composed of a one-atom-thick planar sheet of sp2-bonded carbon atoms perfectly arranged in a honeycomb lattice that has exceptional photonic and electronic properties. We believe that the true potential of graphene lies in optical sensors, especially for biochemical sensing in the diagnostics and health care sector. Graphene has extraordinary properties, such as a one-atom thickness, extremely high surface-to-volume ratio, large surface area, ability to quench fluorescence, excellent biocompatibility, broadband light absorption, ultrafast response time, high mechanical strength, outstanding robustness, and flexibility. The working principle is based on whenever the biomolecules come into contact with graphene, the Fermi level shifts to either p-type or n-type, changing the opto-electronic properties. The most important factors in graphene-based optical sensing are lowering the limit of detection and increasing the specificity of label-free biochemical sensing. This article comprehensively and critically reviews emerging graphene optical biochemical sensors. We first elaborate on their opto-electronic properties, fabrication, numerical modeling and simulation, and then review various sensing applications, such as single-cell detection, neural imaging and optogenetics, colorimetric multifunctional sensors, cancer diagnosis, protein and DNA sensing, and gas sensing. Finally, the roadmap of current and future trends in graphene-based optical biochemical sensors is discussed.Graphene-based optical biochemical sensors are capable of lowering the limit of detection and increasing the specificity of label-free biochemical sensing. The working principle is based on whenever biomolecules come into contact with graphene, the Fermi level will shift either to p-type or n-type, changing its opto-electronic properties. This article comprehensively and critically reviews the emerging graphene optical biochemical sensors.
      PubDate: 2016-11-17T08:10:51.654958-05:
      DOI: 10.1002/adfm.201603918
       
  • Electron Spin Dynamics of Two-Dimensional Layered Materials
    • Authors: Bálint Náfrádi; Mohammad Choucair, László Forró
      Abstract: The growing library of two-dimensional layered materials is providing researchers with a wealth of opportunity to explore and tune physical phenomena at the nanoscale. Here, we review the experimental and theoretical state-of-art concerning the electron spin dynamics in graphene, silicene, phosphorene, transition metal dichalcogenides, covalent heterostructures of organic molecules and topological materials. The spin transport, chemical and defect induced magnetic moments, and the effect of spin-orbit coupling and spin relaxation, are also discussed in relation to the field of spintronics.The growing library of two-dimensional layered materials is providing researchers with a wealth of opportunity to explore and tune physical phenomena at the nanoscale. Here, the experimental and theoretical state-of-art concerning the electron spin dynamics in graphene, silicene, phosphorene, transition metal dichalcogenides, covalent heterostructures of organic molecules and topological materials in relation to the field of spintronics is reviewed.
      PubDate: 2016-11-11T05:00:43.21117-05:0
      DOI: 10.1002/adfm.201604040
       
  • Photodetectors Based on Two-Dimensional Layered Materials Beyond Graphene
    • Authors: Chao Xie; Chunhin Mak, Xiaoming Tao, Feng Yan
      Abstract: Following a significant number of graphene studies, other two-dimensional (2D) layered materials have attracted more and more interest for their unique structures and distinct physical properties, which has opened a window for realizing novel electronic or optoelectronic devices. Here, we present a comprehensive review on the applications of 2D-layered semiconductors as photodetectors, including photoconductors, phototransistors, and photodiodes, reported in the past five years. The device designs, mechanisms, and performances of the photodetectors are introduced and discussed systematically. Emerging techniques to improve device performances by enhancing light-matter interactions are addressed as well. Finally, we deliver a summary and outlook to provide a guideline of the future development of this rapidly growing field.2D layered semiconductors beyond graphene are successfully used in various high-performance photodetectors, including photoconductors, phototransistors, and photodiodes. Here, a comprehensive review on the emerging 2D photodetectors is presented, focusing on the device designs, mechanisms, and performances. Various approaches for the optimization of device performance are introduced. In the end, a summary and an outlook of this field are delivered.
      PubDate: 2016-11-08T08:25:51.004739-05:
      DOI: 10.1002/adfm.201603886
       
  • Two-Dimensional Non-Layered Materials: Synthesis, Properties and
           Applications
    • Authors: Feng Wang; Zhenxing Wang, Tofik Ahmed Shifa, Yao Wen, Fengmei Wang, Xueying Zhan, Qisheng Wang, Kai Xu, Yun Huang, Lei Yin, Chao Jiang, Jun He
      Abstract: Holding novel physical properties, high flexibility and strong integration ability with Si-based electronic devices, two-dimensional (2D) non-layered materials have received considerable attentions in recent years. To achieve the 2D anisotropic growth, various strategies have been developed. And a variety of applications have been demonstrated. This review provides an overview on the recent progress of this material family. The scope will cover the preparation strategies, including dry methods and wet chemical approaches, as well as the applications in catalysis, energy conversion and storage, optoelectronic devices and topological crystalline insulators. Conclusion and future perspectives are also given.Two-dimensional non-layered materials have received considerable attentions in recent years. This review provides an overview on the recent progress of this material family by covering the preparation strategies as well as the applications in catalysis, energy conversion, energy storage, optoelectronic devices, and topological crystalline insulators, and covers future perspectives.
      PubDate: 2016-11-03T08:26:18.656268-05:
      DOI: 10.1002/adfm.201603254
       
  • Two-Dimensional Boron Crystals: Structural Stability, Tunable Properties,
           Fabrications and Applications
    • Authors: Xu Sun; Xiaofei Liu, Jun Yin, Jin Yu, Yao Li, Yang Hang, Xiaocheng Zhou, Maolin Yu, Jidong Li, Guoan Tai, Wanlin Guo
      Abstract: Boron, as a unique element nearest to carbon in the periodic table, has been predicted to form many distinctive two-dimensional (2D) structures that significantly differ from other well-studied 2D materials, owning to its exceptional ability to form strong covalent two-center-two-electron bonds as well as stable electron-deficient multi-center-two-electron bonds. Until recently, the successful syntheses of atomically thin crystalline 2D boron sheets (i.e., borophenes) provoked growing passion in 2D boron crystals. In this feature article, we present a survey of the latest achievements on 2D boron structures, starting from a concise introduction of the structures and properties of the bulk allotropes of boron, boron clusters, and especially potential building blocks for 2D boron crystals. Then we review important achievements and the current status of research on single-layered metallic borophene, and discuss 2D few-layered boron sheets, from their possible structures to tunable properties and potential applications in electronics, spintronics, and photoelectronics. We also systematically investigate the stability and functionalization of 2D icosahedral boron sheets in comparison with borophenes through first-principles studies. Finally, we present an outlook on the advance in fabrications of 2D boron sheets, and the challenges and prospects in the realm of 2D boron crystals.Boron bulk allotropes and clusters with unique bonding and structures have drawn long-standing interest. Now, boron of a new dimensionality, namely 2D boron crystals, has emerged into the vision of scientific communities, especially with the success of their experimental synthesis achieved in the last year. Here, we review state-of-the-art experimental and theoretical achievements on 2D boron crystals, with special attention paid to their possible structures, tunable properties, and potential applications.
      PubDate: 2016-11-02T08:02:31.290223-05:
      DOI: 10.1002/adfm.201603300
       
  • Suppression of Defects and Deep Levels Using Isoelectronic Tungsten
           Substitution in Monolayer MoSe2
    • Authors: Xufan Li; Alexander A. Puretzky, Xiahan Sang, Santosh KC, Mengkun Tian, Frank Ceballos, Masoud Mahjouri-Samani, Kai Wang, Raymond R. Unocic, Hui Zhao, Gerd Duscher, Valentino R. Cooper, Christopher M. Rouleau, David B. Geohegan, Kai Xiao
      Abstract: Defects formed during chemical vapor deposition (CVD) of two-dimensional (2D) transition metal dichalcogenides (TMDs) currently limit their quality and optoelectronic properties. Effective synthesis and processing strategies to suppress defects and enhance the quality of 2D TMDs are urgently needed to enable next generation optoelectronic devices. In this work, isoelectronic doping is presented as a new strategy to form stable alloys and suppress defects and enhance photoluminescence (PL) in CVD-grown TMD monolayers. The isoelectronic substitution of W atoms for Mo atoms in CVD-grown monolayers of Mo1–xWxSe2 (0 < x < 0.18) is shown to effectively suppress Se vacancy concentration by 50% compared to those found in pristine MoSe2 monolayers, resulting in a decrease in defect-mediated nonradiative recombination, ≈10 times more intense PL, and an increase in the carrier lifetime by a factor of 3. Theoretical predictions reveal that isoelectronic W alloying to form Mo1–xWxSe2 monolayers raises the energy of deep level defects in MoSe2 to enable faster quenching, which is confirmed by low temperature (4–125 K) PL from defect-related localized states. Isoelectronic substitution therefore appears to be a promising synthetic method to control the heterogeneity of 2D TMDs to realize the scalable production of high performance optoelectronic and electronic devices.Isoelectronic tungsten alloying in MoSe2 monolayers, forming Mo1–xWxSe2, suppresses both the formation of Se vacancies in the lattice and the deep levels in the electronic bandgap. As a result, the photoluminescence is greatly enhanced by up to 10 times.
      PubDate: 2016-10-31T05:10:40.076648-05:
      DOI: 10.1002/adfm.201603850
       
  • Creating the Smallest BN Nanotube from Bilayer h-BN
    • Authors: Tao Xu; Yilong Zhou, Xiaodong Tan, Kuibo Yin, Longbing He, Florian Banhart, Litao Sun
      Abstract: Single-wall nanotubes of boron nitride (BN) are among the most promising quasi-1D materials with outstanding mechanical strength. However, synthesizing them in a controlled and reproducible way remains challenging. Here the authors show a technique of creating BN tubes by cutting bilayer BN sheets with an electron beam and interconnecting the two layers at an open edge. The in situ experiments in an electron microscope show that the spontaneous interlinking of the two layers leads to flattened tubular structures when a narrow ribbon is created. Below a certain width of the ribbon, van der Waals interaction between the layers is overbalanced by the stress in the layer so that the walls separate and a tube with circular diameter forms. The smallest stable BN tubes with a diameter of 0.45 nm, corresponding to a (3,3) tube, can be produced by this technique. The diameter can only be decreased in discrete steps, showing that all possible BN tubes with a given axis alignment relative to the BN lattice can be made. This is a novel top-down approach that allows the authors to create and study a variety of ultrathin nanotubes from related 2D materials.Electron beam structuring provides a top-down approach to create boron nitride (BN) tubes by cutting bilayer BN sheets. Covalent interlayer bonds form spontaneously at two parallel zigzag edges, resulting in formation of armchair BN tubes. The diameter can only be decreased in discrete steps to 0.45 nm, corresponding to a (3,3) tube, which is the smallest tubes observed experimentally so far.
      PubDate: 2016-10-28T06:57:06.173614-05:
      DOI: 10.1002/adfm.201603897
       
  • On Optical Dipole Moment and Radiative Recombination Lifetime of Excitons
           in WSe2
    • Authors: Chenhao Jin; Jonghwan Kim, Kedi Wu, Bin Chen, Edward S. Barnard, Joonki Suh, Zhiwen Shi, Steven G. Drapcho, Junqiao Wu, Peter James Schuck, Sefaattin Tongay, Feng Wang
      Abstract: Optical dipole moment is the key parameter of optical transitions, as it directly determines the strength of light–matter interaction such as intrinsic radiative lifetime. However, experimental determination of these fundamental properties of excitons in monolayer WSe2 is largely limited, because the commonly used measurement, such as (time-resolved) photoluminescence, is inherently difficult to probe the intrinsic properties. For example, dark states below bright exciton can change the photoluminescence emission rate by orders of magnitude and gives an “effective” radiative lifetime distinctive from the intrinsic one. On the other hand, such “effective” radiative lifetime becomes important itself because it describes how dark states affect exciton dynamics. Unfortunately, the “effective” radiative lifetime in monolayer WSe2 is also not determined as it requires photoluminescence measurement with resonant excitation, which is technically difficult. These difficulties are overcome here to obtain both the “intrinsic” and “effective” radiative lifetime experimentally. A framework is developed to determine the dipole moment and “intrinsic” radiative lifetime of delocalized excitons in monolayer WSe2 from the absorption measurements. In addition, the “effective” radiative lifetime in WSe2 is obtained through time-resolved photoluminescence and absolute quantum-yield measurement at resonant excitation. These results provide helpful information for fundamental understanding of exciton light–matter interaction in WSe2.The dipole moment and “intrinsic” radiative lifetime of excitons in WSe2 are determined from absorption measurements. The “effective” radiative lifetime of excitons is also obtained using time-resolved photoluminescence and absolute quantum yield measurements with resonant excitation. The framework developed provides helpful information to determine fundamental quantities of exciton light–matter interaction, and to understand the dynamics of delocalized excitons in solids.
      PubDate: 2016-09-27T05:02:13.590594-05:
      DOI: 10.1002/adfm.201601741
       
  • Controllable Synthesis of 2D and 1D MoS2 Nanostructures on Au Surface
    • Authors: Hai Xu; Zijing Ding, Chang Tai Nai, Yang Bao, Fang Cheng, Sherman J. R. Tan, Kian Ping Loh
      Abstract: A bottom-up growth approach based on the assembly of binary atomic constituents delivers precise control over the edge termination and dimensions of nanostructures. Here, the dimensional crossover of MoS2 from 1D nanoribbons to 2D islands synthesized by the assembly of Mo and S atoms on Au(100) surface is studied. Low-temperature scanning tunneling microscopy and in situ Q-plus non-contact atomic force microscopy are employed to elucidate the edge structure of MoS2 nanoribbons at the atomic scale, where three types of zigzag Mo-edges with different sulfur terminations are observed. It is found that the thermodynamic instability of the armchair edges causes the 1D system to develop faceted zigzag edges which manifests in the morphological evolution from 1D ribbons to 2D triangles as the system size increases.The dimensional crossover of MoS2 from 1D nanoribbons to 2D islands synthesized by the assembly of Mo and S atoms on Au(100) surface is studied. It is found that the thermodynamic instability of the armchair edges causes the 1D system to develop faceted zigzag edges, which manifests in the morphological evolution from 1D ribbons to 2D triangles as the system size increases.
      PubDate: 2016-09-20T08:40:45.138879-05:
      DOI: 10.1002/adfm.201603887
       
  • Toward High Energy Organic Cathodes for Li-Ion Batteries: A Case Study of
           Vat Dye/Graphene Composites
    • Authors: Wei Ai; Weiwei Zhou, Zhuzhu Du, Chencheng Sun, Jun Yang, Yu Chen, Zhipeng Sun, Shun Feng, Jianfeng Zhao, Xiaochen Dong, Wei Huang, Ting Yu
      Abstract: Despite the fascinating Li storage properties of organic carbonyl compounds, e.g., high therotical capacity and fast kinetics, it is still lack of a facile and effective way that capable of large-scale producion of advanced carbonyl cathodes for Li-ion batteries (LIBs). Here, a generic strategy is proposed by combining sonication and hydrothermal techniques for scalable synthesis of high performance organic carbonyl cathodes for LIBs. A series of commercialized vat dyes with abundant electroactive conjugated carbonyl groups are confined in between the graphene layers, forming a compatible 3D hybrid architecture. The unique structure affords good Li+ ions accessibility to the electrode and short Li+ ions diffusion length. Meanwhile, each sandwiched graphene layer functions as a miniature current collector, ensuring fast electron transport throughout the entire electrode. Consequently, the cathodic performances of LIBs using the composites as electrodes, for example, Vat Green 8/graphene, Vat Brown BR/graphene, and Vat Olive T/graphene, possess high specific capacity, exceptional cycling stability, and excellent rate capability. The effect of vat dye content on the morphology, structure, and the final electrochemical performance of the composites is investigated as well. This work provides a versatile and low-cost platform for large-scale development of advanced organic-based electrodes toward sustainable energy fields.A versatile strategy involving the combination of sonication and hydrothermal techniques is successfully developed for scalable fabrication of vat dye/graphene composites. The commercialized vat dyes with electroactive conjugated carbonyl groups are confined between the graphene layers, forming a compatible 3D hybrid architecture. This unique structural feature provides the composites with superior cathodic performance for Li storage.
      PubDate: 2016-09-20T06:20:58.615916-05:
      DOI: 10.1002/adfm.201603603
       
  • Band Alignment of 2D Transition Metal Dichalcogenide Heterojunctions
    • Authors: Ming-Hui Chiu; Wei-Hsuan Tseng, Hao-Ling Tang, Yung-Huang Chang, Chang-Hsiao Chen, Wei-Ting Hsu, Wen-Hao Chang, Chih-I Wu, Lain-Jong Li
      Abstract: It is critically important to characterize the band alignment in semiconductor heterojunctions (HJs) because it controls the electronic and optical properties. However, the well-known Anderson's model usually fails to predict the band alignment in bulk HJ systems due to the presence of charge transfer at the interfacial bonding. Atomically thin 2D transition metal dichalcogenide materials have attracted much attention recently since the ultrathin HJs and devices can be easily built and they are promising for future electronics. The vertical HJs based on 2D materials can be constructed via van der Waals stacking regardless of the lattice mismatch between two materials. Despite the defect-free characteristics of the junction interface, experimental evidence is still lacking on whether the simple Anderson rule can predict the band alignment of HJs. Here, the validity of Anderson's model is verified for the 2D heterojunction systems and the success of Anderson's model is attributed to the absence of dangling bonds (i.e., interface dipoles) at the van der Waal interface. The results from the work set a foundation allowing the use of powerful Anderson's rule to determine the band alignments of 2D HJs, which is beneficial to future electronic, photonic, and optoelectronic devices.The band alignment of stacked 2D material heterojunctions is experimentally proven to follow the Anderson's model. Based on this discovery it is demonstrated that electron affinity and band gap values are sufficient to construct the band alignment of stacked 2D heterojunctions.
      PubDate: 2016-09-20T06:15:24.867003-05:
      DOI: 10.1002/adfm.201603756
       
  • Wettability of Supported Monolayer Hexagonal Boron Nitride in Air
    • Authors: Xuemei Li; Hu Qiu, Xiaofei Liu, Jun Yin, Wanlin Guo
      Abstract: Hexagonal boron nitride (h-BN), a wide band gap monolayer crystal with structure similar to graphene, is optically transparent with exceptionally high thermal and chemical stability, and should be ideal to serve as an atomically thin coating. However, limited by the challenges in fabricating h-BN of high quality in large area, the wetting performance of h-BN has seldom been studied. Here, it is shown that the water contact angle of freshly grown h-BN film is nearly independent of the underlying materials as well as the h-BN layer number, but increases gradually to a saturated stable value in air due to the spontaneous adsorption of airborne hydrocarbon. First-principles calculations and molecular interaction modeling confirm that a monolayer h-BN coating does efficiently tune the interaction of a water molecule with different substrates to a converging level. The saturated wettability of h-BN coating is robust against variation of several factors, facilitating its practical applications.Wettability of 2D h-BN is investigated with regard to the substrate dependence and effect of airborne contaminants. The water contact angle of a freshly prepared h-BN monolayer is independent of the substrates, but increases in ambient air due to the adsorption of airborne contaminants. The saturated contact angle in air is robust, facilitating the practical applications.
      PubDate: 2016-09-15T01:12:03.645247-05:
      DOI: 10.1002/adfm.201603181
       
  • Performance Limits of the Self-Aligned Nanowire Top-Gated MoS2 Transistors
    • Authors: Zhenyu Yang; Xingqiang Liu, Xuming Zou, Jingli Wang, Chao Ma, Changzhong Jiang, Johnny C. Ho, Caofeng Pan, Xiangheng Xiao, Jie Xiong, Lei Liao
      Abstract: In order to realize the promising potential of MoS2 as the alternative channel material, it is essential to achieve high-performance top-gated MoS2 field-effect transistors (FETs), especially since the back-gated counterparts cannot control the device individually. Although uniform high-k dielectric films, such as HfO2, can be obtained through the introduction of artificial nucleation sites on the MoS2 channel to fabricate top-gated FETs, this would inevitably degrade their channel/dielectric interface quality, induce significant charged impurity scattering and lower carrier mobility. In this work, MoS2 FETs are fabricated using a self-aligned nanowire top-gate, which can effectively reduce the charged impurity scattering on the surface of MoS2. Specifically, the fabricated short-channel devices exhibit impressive electrical performances, such as the high on/off current ratio, low interface trap density, and near-ideal subthreshold slope at room temperature. In addition, the short channel effect is systematically analyzed, which indicates that the phonon scattering can be the dominant scattering mechanism in the devices when the amount of charged impurities is effectively reduced with the self-aligned nanowire gate. All these provide an enhanced fabrication scheme to attain top-gated short-channel devices with the optimized interface and potentially to explore their corresponding performance limits.MoS2 field effect transistors using a self-aligned nanowire top-gate exhibit a reduced charged impurity scattering in their channel/gate interface. Considering their short channel lengths, all devices exhibit an impressive electrical performance at room temperature. In addition, the performance degradation resulting from the short channel effects is systematically analyzed.
      PubDate: 2016-08-17T06:25:56.336246-05:
      DOI: 10.1002/adfm.201602250
       
  • Giant Anisotropic Raman Response of Encapsulated Ultrathin Black
           Phosphorus by Uniaxial Strain
    • Authors: Yanyong Li; Zhixin Hu, Shenghuang Lin, Sin Ki Lai, Wei Ji, Shu Ping Lau
      Abstract: The giant anisotropic Raman response of encapsulated ultrathin black phosphorus (BP) is reported by uniaxial strain. A modified bending technique is employed to apply precise uniaxial tensile strain along the zigzag or armchair direction of the ultrathin BP encapsulated by a layer of polymethyl methacrylate. The Raman shift rates of the A1g, B2g, and A2g modes are significantly distinct for strain applied along different directions. For the strain applied along zigzag direction, the Raman shift rate of the B2g mode can reach a remarkable value of ≈−11 cm−1/% strain. In addition, the Grüneisen parameter is as high as ≈2.5, which is the largest among all the reported common 2D materials. Density functional perturbation theory calculations are performed to understand the exceptional anisotropic strain response discovering that not only the bond lengths but also the bond angels are changed in the strained ultrathin BP, which lead to the giant anisotropic Raman response. Furthermore, an alternative method based entirely on the strained ultrathin BP and nonpolarized Raman spectroscopy is demonstrated to determine the crystallographic orientations of ultrathin BP. This work paves a way to study the strain-induced anisotropic electrical conductance and magnetotransport properties of BP.Giant anisotropic Raman response in ultrathin black phosphorus is investigated using a modified bending technique. The Raman shift rate and Grüneisen parameter of the B2g mode can reach colossal values of ≈−11 cm−1/% strain and ≈2.5, respectively, under uniaxial strain applied along zigzag direction.
      PubDate: 2016-06-22T03:15:40.761094-05:
      DOI: 10.1002/adfm.201600986
       
 
 
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