for Journals by Title or ISSN
for Articles by Keywords
  Subjects -> CHEMISTRY (Total: 839 journals)
    - ANALYTICAL CHEMISTRY (47 journals)
    - CHEMISTRY (590 journals)
    - CRYSTALLOGRAPHY (22 journals)
    - ELECTROCHEMISTRY (26 journals)
    - INORGANIC CHEMISTRY (41 journals)
    - ORGANIC CHEMISTRY (45 journals)
    - PHYSICAL CHEMISTRY (68 journals)

CHEMISTRY (590 journals)                  1 2 3 4 5 6 | Last

2D Materials     Hybrid Journal   (Followers: 5)
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: 28)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 16)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 18)
ACS Macro Letters     Full-text available via subscription   (Followers: 20)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 25)
ACS Nano     Full-text available via subscription   (Followers: 247)
ACS Photonics     Full-text available via subscription   (Followers: 5)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 16)
Acta Chemica Iasi     Open Access  
Acta Chimica Sinica     Full-text available via subscription  
Acta Chimica Slovaca     Open Access   (Followers: 5)
Acta Chromatographica     Full-text available via subscription   (Followers: 9)
Acta Facultatis Medicae Naissensis     Open Access   (Followers: 1)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 7)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 5)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 5)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 10)
Advanced Functional Materials     Hybrid Journal   (Followers: 43)
Advanced Science Focus     Free   (Followers: 2)
Advances in Chemical Engineering and Science     Open Access   (Followers: 26)
Advances in Chemical Science     Open Access   (Followers: 10)
Advances in Chemistry     Open Access  
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 14)
Advances in Drug Research     Full-text available via subscription   (Followers: 19)
Advances in Environmental Chemistry     Open Access  
Advances in Enzyme Research     Open Access   (Followers: 1)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 7)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 13)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 15)
Advances in Nanoparticles     Open Access   (Followers: 12)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 10)
Advances in Polymer Science     Hybrid Journal   (Followers: 37)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 7)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 11)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6)
African Journal of Chemical Education     Open Access   (Followers: 1)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 5)
Afrique Science : Revue Internationale des Sciences et Technologie     Open Access   (Followers: 1)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 1)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 4)
AMB Express     Open Access  
Ambix     Hybrid Journal   (Followers: 2)
American Journal of Applied Sciences     Open Access   (Followers: 32)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 121)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 11)
American Journal of Chemistry     Open Access   (Followers: 23)
American Journal of Plant Physiology     Open Access   (Followers: 11)
American Mineralogist     Full-text available via subscription   (Followers: 7)
Analyst     Full-text available via subscription   (Followers: 38)
Angewandte Chemie     Hybrid Journal   (Followers: 21)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 184)
Annales UMCS, Chemia     Open Access   (Followers: 2)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 1)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 1)
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: 10)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 13)
Anti-Infective Agents     Hybrid Journal   (Followers: 2)
Antiviral Chemistry and Chemotherapy     Full-text available via subscription  
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 4)
Applied Spectroscopy     Full-text available via subscription   (Followers: 16)
Applied Surface Science     Hybrid Journal   (Followers: 22)
Arabian Journal of Chemistry     Full-text available via subscription   (Followers: 6)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 5)
Autophagy     Hybrid Journal   (Followers: 3)
Avances en Quimica     Open Access   (Followers: 1)
Biochemical Pharmacology     Hybrid Journal   (Followers: 6)
Biochemistry     Full-text available via subscription   (Followers: 199)
Biochemistry Insights     Open Access   (Followers: 4)
Biochemistry Research International     Open Access   (Followers: 5)
BioChip Journal     Hybrid Journal   (Followers: 1)
Bioinorganic Chemistry and Applications     Open Access   (Followers: 5)
Bioinspired Materials     Open Access   (Followers: 1)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 1)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access  
Biomacromolecules     Full-text available via subscription   (Followers: 19)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 7)
Biomedical Chromatography     Hybrid Journal   (Followers: 7)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 2)
BioNanoScience     Partially Free   (Followers: 4)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 31)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 25)
Bioorganic Chemistry     Hybrid Journal   (Followers: 5)
Biopolymers     Hybrid Journal   (Followers: 16)
Biosensors     Open Access   (Followers: 3)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 3)
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 3)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 14)
C - Journal of Carbon Research     Open Access  
Cakra Kimia (Indonesian E-Journal of Applied Chemistry)     Open Access  
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 4)
Canadian Journal of Chemistry     Full-text available via subscription   (Followers: 5)

        1 2 3 4 5 6 | Last

Journal Cover   Advanced Functional Materials
  [SJR: 4.682]   [H-I: 156]   [43 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  [1597 journals]
  • Quaternized Pyridyloxy Phthalocyanines Render Aqueous Electron‐Donor
           Carbon Nanotubes as Unprecedented Supramolecular Materials for Energy
    • Abstract: Exploring new properties in known materials, sometimes even achieving behaviors opposite to those traditionally encountered, is a fundamental aspect of innovation in materials science. In the field of energy conversion, for example, the development of water‐processed organic solar cells provides environmentally friendlier materials, which contribute to reduce health risks. Herein, a novel approach is described to produce water‐soluble electron‐donor single wall carbon nanotube (SWCNT) hybrids based on the noncovalent immobilization of quaternized pyridyloxy zinc phthalocyanines (ZnPc) with a varying number of pyridyl substituents. Moreover, the excellent electron‐accepting ability of the latter ZnPcs is reported. The introduction of tert‐butylphenyl groups at the pyridines enables for the first time a complete characterization. The electron‐acceptor nature of the ZnPcs enables switching the role of SWCNTs within the resulting supramolecular hybrids. Finally, a proof‐of‐concept demonstration of the SWCNT/ZnPc hybrids' capacity for energy conversion is presented, paving their way to possible use as active layer material in solar cells processed entirely from aqueous solutions. Aqueous carbon nanotube hybrids are developed through supramolecular immobilization of quaternized pyridyloxy phthalocynanines (ZnPc). The water‐solubility and excellent electron‐accepting features of these ZnPc derivatives switch the redox and photophysical properties of single wall carbon nanotubes, which can actually be used for energy conversion.
      PubDate: 2015-11-27T02:18:20.432243-05:
      DOI: 10.1002/adfm.201503002
  • Isotropic Holographic Metasurfaces for Dual‐Functional Radiations
           without Mutual Interferences
    • Authors: Yun Bo Li; Ben Geng Cai, Qiang Cheng, Tie Jun Cui
      Abstract: The dual‐functional and/or multifunctional devices have huge fascinations and prospects to conveniently integrate complex systems with low costs. However, most of such devices are based on anisotropic media or anisotropic structures. Here, a new method is proposed to design planar dual‐functional devices using an isotropic holographic metasurface, in which two different functions are written on the same holographic interference pattern with no mutual coupling. When the metasurface is excited by two orthogonally ported sources, the corresponding dual functions can be controlled by the object waves, which are not affected by each other due to suppression of mutual interference. The proposed metasurface is composed of subwavelength‐scale isotropic metallic patches on a grounded dielectric. In this specific design, double‐beam and double‐polarization radiate devices are realized independently by the orthogonal excitations. Based on the theoretical analysis, scanning radiate beams that are only controlled by frequency with different performances under orthogonal polarizations are demonstrated. To the best of our knowledge, this is the first time for actualizing dual‐functional devices using isotropic textures. Full‐wave simulations and experimental results in the microwave frequencies are presented to validate the proposed theory and confirm the corresponding physical phenomena. A new methodis proposed to design planar dual‐functional devices using isotropic holographic metasurface, in which two different functions are written on the same hologram with no mutual coupling. In this specific design, double‐beam or double‐polarization radiate devices are realized independently by orthogonal excitations. Scanning radiate beams that are only controlled by frequency with different performances under orthogonal polarizations are demonstrated.
      PubDate: 2015-11-27T02:17:57.166446-05:
      DOI: 10.1002/adfm.201503654
  • Comment on “Interesting Evidence for Template‐Induced
           Ferroelectric Behavior in Ultra‐Thin Titanium Dioxide Films Grown on
           (110) Neodymium Gallium Oxide Substrates”
    • Authors: Stella Skiadopoulou; Stanislav Kamba, Jan Drahokoupil, Jan Kroupa, Nitin Deepak, Martyn E. Pemble, Roger W. Whatmore
      Abstract: X‐ray diffraction, second‐harmonic generation and infrared reflectance investigations reveal no evidence for a polar phase or ferroelectric phase transition in 1.6% tensile strained anatase TiO2 thin films. This indicates that the previously‐reported potential ferroelectric behaviour, observed using piezoelectric force microscopy, may have been defect related, or the polar distortion is too small to detect using these methods.
      PubDate: 2015-11-24T08:21:39.156468-05:
      DOI: 10.1002/adfm.201502441
  • Nanoimprinted, Submicrometric, MOF‐Based 2D Photonic Structures:
           Toward Easy Selective Vapors Sensing by a Smartphone Camera
    • Abstract: In this work, a soft‐lithographic approach to fabricate submicrometer metal organic framework (MOF)‐based 2D photonic structures is described. Nanometric zeolitic imidazole framework material ZIF‐8 (zinc) is chosen as the sensible MOF material because of its chemical stability and its vapor selective adsorption properties. Two different systems are fabricated: nanopatterned colloidal ZIF‐8 homo‐ and ZIF‐8/TiO2 heterostructures. Several features (stripes, squares, etc.) with dimensions of 200 nm are replicated on different substrates such as silicon, flexible plastics, and even aluminum cans, over relatively large surfaces (up to 1 cm2). In addition, the use of these photonic MOF‐heterostructures as very low‐cost sensing platforms compatible with smartphone technology is demonstrated. This method relies on the evaluation of the change in diffraction efficiency of the photonic MOF‐patterns, induced by the MOF refractive index variation, which is simply detected by a charge coupled device (CCD) camera, as those integrated in smartphones, without need for complex optical instrumentations for transduction data processing. Performances of the sensors are first evaluated using isopropyl alcohol adsorption/desorption cycling as a model case. In addition, a “real” environmental issue is tackled. Selective detection of styrene in presence of interfering water is demonstrated at concentrations below the human permissible exposure limit. In situ ellispometric analyses are also carried out in order to confirm the sensor performances and to propose a mechanism for styrene uptake into the nanoMOFs. 2D Photonic metal–organic framework (MOF)‐based homo‐ and heterostructures are fabricated by soft‐lithographic approaches. This versatile approach allows preparation of large‐scale patterned surfaces on several substrates including flexible plastics. The materials are used as selective optical sensing platform. Detection of toxic vapors such as styrene is performed by using an easy transduction method, compatible with smartphone camera technology.
      PubDate: 2015-11-24T08:21:35.085413-05:
      DOI: 10.1002/adfm.201503016
  • A Cross‐Linkable Donor Polymer as the Underlying Layer to Tune the
           Active Layer Morphology of Polymer Solar Cells
    • Authors: Bin Meng; Zaiyu Wang, Wei Ma, Zhiyuan Xie, Jun Liu, Lixiang Wang
      Abstract: For polymer solar cells (PSCs) with conventional configuration, the vertical composition profile of donor:acceptor in active layer is detrimental for charge carrier transporting/collection and leads to decreased device performance. A cross‐linkable donor polymer as the underlying morphology‐inducing layer (MIL) to tune the vertical composition distribution of donor:acceptor in the active layer for improved PSC device performance is reported. With poly(thieno[3,4‐b]‐thiophene/benzodithiophene):[6,6]‐phenyl C71‐butyric acid methyl ester (PTB7:PC71BM) as the active layer, the MIL material, PTB7‐TV, is developed by attaching cross‐linkable vinyl groups to the side chain of PTB7. PSC device with PTB7‐TV layer exhibits a power conversion efficiency (PCE) of 8.55% and short‐circuit current density (JSC) of 15.75 mA cm−2, in comparison to PCE of 7.41% and JSC of 13.73 mA cm−2 of the controlled device. The enhanced device performance is ascribed to the much improved vertical composition profile and reduced phase separation domain size in the active layer. These results demonstrate that cross‐linked MIL is an effective strategy to improve photovoltaic performance of conventional PSC devices. A cross‐linkable donor polymer is developed and used as the underlying layer to improve the vertical composition distribution of donor:acceptor in the active layer of polymer solar cells (PSCs). With the improvement, the regular PSC device based on PTB7:PC71BM active layer exhibits power conversion efficiency increase from 7.41% to 8.55%.
      PubDate: 2015-11-24T08:21:26.168689-05:
      DOI: 10.1002/adfm.201503833
  • Sustainable Synthesis and Assembly of Biomass‐Derived B/N
           Co‐Doped Carbon Nanosheets with Ultrahigh Aspect Ratio for
           High‐Performance Supercapacitors
    • Authors: Zheng Ling; Zhiyu Wang, Mengdi Zhang, Chang Yu, Gang Wang, Yanfeng Dong, Shaohong Liu, Yuwei Wang, Jieshan Qiu
      Abstract: The practical application of graphene has still been hindered by high cost and scarcity in supply. It boosts great interest in seeking for low‐cost substitute of graphene for upcoming usage where extremely physical properties are not absolutely critical. The conversion of renewable biomass offers a great opportunity for sustainable and economic fabrication of 2D carbon nanostructures. However, large‐scale production of carbon nanosheets with ultrahigh aspect ratio, satisfied electronic properties, and the capability of organized assembly like graphene has been rarely reported. In this work, a facile yet efficient approach for mass production of flexible boric/nitrogen co‐doped carbon nanosheets with very thin thickness of 5–8 nm and ultrahigh aspect ratio of over 6000–10 000 is demonstrated by assembling the biomass molecule in long‐range order on 2D hard template and subsequent annealing. The advantage of these doped carbon nanosheets over conventional products lies in that they can be readily assembled to multilevel architectures such as freestanding flexible thin film and ultralight aerogels with better electrical properties, which exhibit exceptional capacitive performance for supercapacitor application. The recyclability of boric acid template further reduces the discharge of the waste and processing cost, rendering high cost‐effectiveness and environmental benignity for scalable production. B/N co‐doped carbon nanosheets with ultrahigh aspect ratio are synthesized by assembling the biomass molecule in long‐range order on recyclable 2D hard template followed by annealing. The unique structural features allow them to be assembled to flexible thin films and ultralight aerogels for superior charge storage in supercapacitors.
      PubDate: 2015-11-24T08:18:18.26034-05:0
      DOI: 10.1002/adfm.201504004
  • Tunable Self‐Assembled Micro/Nanostructures of
           Carboxyl‐Functionalized Squarylium Cyanine for Ammonia Sensing
    • Authors: Jie Li; Baozhong Lv, Dongpeng Yan, Shouke Yan, Min Wei, Meizhen Yin
      Abstract: Orderly molecular self‐assembly for tunable micro/nanostructures is an effective way to prepare novel functional materials with desired properties. Squarylium cyanine (SCy) dyes have received great attention in the fields of laser, imaging, and optoelectronic device. However, the detailed self‐assembly behavior of SCy has rarely been investigated. In the present work, two SCy derivatives, D1 and D2, respectively, bearing four and two carboxylic acid groups at different positions are prepared and used as a model system to investigate the molecular self‐assembly, morphology, and optical properties of SCy dyes. The hydrogen‐bonding interactions between the carboxylic acid groups in D1 and D2 are determined with X‐ray diffraction, 2D nuclear magnetic resonance, and Fourier transformation infrared spectroscopy. The two types of hydrogen bonds in D1 cooperating with inherent π–π stacking interaction result in tunable molecular aggregations, which further leads to the transformation between J‐aggregation and H‐aggregation of D1 in the solid state in response to ammonia gas. In all, this work provides a feasible and effective way to study the self‐assembled aggregates of SCy dyes at both molecular and supramolecular levels, and has developed a reversible sensor for ammonia gas detection. Squarylium cyanine dyes D1 and D2, containing different numbers of carboxylic acid groups, are utilized as a model system to investigate the self‐assembly behaviors based on hydrogen bonding and π–π stacking. These driving forces synergistically construct the unique morphologies of D1 and D2 by forming distinct distances in repeated units, which makes the D1 reversibly responsive to ammonia gas.
      PubDate: 2015-11-24T03:16:24.818314-05:
      DOI: 10.1002/adfm.201503825
  • Masthead: (Adv. Funct. Mater. 44/2015)
    • PubDate: 2015-11-23T06:56:46.892769-05:
      DOI: 10.1002/adfm.201570284
  • Semiconductor‐Based Photoelectrochemical Water Splitting at the
           Limit of Very Wide Depletion Region
    • Authors: Mingzhao Liu; John L. Lyons, Danhua Yan, Mark S. Hybertsen
      Abstract: In semiconductor‐based photoelectrochemical (PEC) water splitting, carrier separation and delivery largely relies on the depletion region formed at the semiconductor/water interface. As a Schottky junction device, the trade‐off between photon collection and minority carrier delivery remains a persistent obstacle for maximizing the performance of a water splitting photoelectrode. Here, it is demonstrated that the PEC water splitting efficiency for an n‐SrTiO3 (n‐STO) photoanode is improved very significantly despite its weak indirect band gap optical absorption (α < 104 cm−1), by widening the depletion region through engineering its doping density and profile. Graded doped n‐SrTiO3 photoanodes are fabricated with their bulk heavily doped with oxygen vacancies but their surface lightly doped over a tunable depth of a few hundred nanometers, through a simple low temperature reoxidation technique. The graded doping profile widens the depletion region to over 500 nm, thus leading to very efficient charge carrier separation and high quantum efficiency (>70%) for the weak indirect transition. This simultaneous optimization of the light absorption, minority carrier (hole) delivery, and majority carrier (electron) transport by means of a graded doping architecture may be useful for other indirect band gap photocatalysts that suffer from a similar problem of weak optical absorption. Water photolysis over semiconducting metal oxide is studied at the limit of very wide depletion region for n‐SrTiO3 photoanodes. Through a graded doping architecture, the depletion region is widened to an unprecedented depth of 500+ nm, which optimizes the trade‐off between photon collection and minority carrier delivery, leading to an incident photon‐to‐current efficiency over 70% for its weak indirect band gap absorption.
      PubDate: 2015-11-23T06:41:54.55582-05:0
      DOI: 10.1002/adfm.201503692
  • Gold Nanobipyramid‐Supported Silver Nanostructures with Narrow
           Plasmon Linewidths and Improved Chemical Stability
    • Authors: Xingzhong Zhu; Xiaolu Zhuo, Qian Li, Zhi Yang, Jianfang Wang
      Abstract: Silver nanostructures with narrow plasmon linewidths and good chemical stability are strongly desired for plasmonic applications. Herein, a facile method is discussed for the preparation of Ag nanostructures with narrow plasmon linewidths and improved chemical stability through Ag overgrowth on monodispersed Au nanobipyramids. Structural evolution from bipyramid through rice to rod is observed, indicating that Ag atoms are preferentially deposited on the side surfaces of Au nanobipyramids. The resultant (Au nanobipyramid)@Ag nanostructures possess high size and shape uniformities, and much narrower plasmon linewidths than other Ag nanostructures. The spectral evolution of the supported Ag nanostructures is ascertained by both ensemble and single‐particle characterizations, together with electrodynamic simulations. Systematic measurements of the refractive index sensing characteristics indicate that Ag nanostructures in this study possess high index sensitivities and figure of merit (sensitivity divided by linewidth) values. Moreover, Ag nanostructures in this study exhibit greatly improved chemical stability. The superior sensing capability of Ag nanostructures in this study is further demonstrated by the detection of sulfide ions at a relatively low detection limit. Taken together, results of this study show that the Au‐nano­bipyramid‐supported Ag nanostructures will be an outstanding candidate for the design of ultrasensitive plasmonic sensing devices as well as for the development of other plasmon‐enabled technological applications. Silver nanostructures of controllable plasmon wavelengths are synthesized by use of highly pure, highly uniform gold nanobipyramids as supports. They are nearly monodispersed in size and shape, possess narrow plasmon linewidths, high refractive index sensitivities, and figure of merit values. They are expected to be useful in developing ultrasensitive plasmonic sensors.
      PubDate: 2015-11-23T03:16:38.799149-05:
      DOI: 10.1002/adfm.201503670
  • Hollow ZSM‐5 with Silicon‐Rich Surface, Double Shells, and
           Functionalized Interior with Metallic Nanoparticles and Carbon Nanotubes
    • Authors: Chengyi Dai; Anfeng Zhang, Min Liu, Xinwen Guo, Chunshan Song
      Abstract: Hollow ZSM‐5 single crystals with silicon‐rich exterior surface are prepared by a “dissolution–recrystallization” strategy in tetrapropylammonium hydroxide solution. Selective dissolution and exterior recrystallization cause the silicon components to migrate from the inside to outside, resulting in a regular void in the interior of the crystal, increased Brönsted acid sites and a silicon‐rich external surface. The as‐prepared hollow ZSM‐5 exhibits excellent acid catalysis with enhanced shape selectivity, as shown in biphenyl methylation as a probe reaction, which is attributed to the silicon‐rich external surface and thus the inhibition of isomerization on external surface. More interestingly, hollow ZSM‐5 single crystals with double shells are successfully prepared by layer‐by‐layer technique followed with dissolution–recrystallization strategy. Furthermore, hollow ZSM‐5 encapsulating iron and carbon nanotubes are successfully synthesized. Furthermore, hollow ZSM‐5 nanosized crystals with the interior functionalized as bimetallic (oxide) nanoparticles such as CuO‐Pd are also successfully synthesized. Hollow ZSM‐5 single crystals with double shells, regular void in the crystal interior, enhanced acidity, increased Brönsted acid sites, silicon‐rich exterior, adjustable Si/Al ratio, and crystal size, as well as with Fe2O3, bimetals ca. Cu‐Pd, Cu‐Pt, Fe‐Au, and carbon nanotubes functionalized interior are prepared by “dissolution–recrystallization” strategy in tetrapropylammonium hydroxide solution.
      PubDate: 2015-11-20T07:14:26.195585-05:
      DOI: 10.1002/adfm.201502980
  • Tuning the Excitonic States in MoS2/Graphene van der Waals
           Heterostructures via Electrochemical Gating
    • Abstract: The behavior of excitons in van der Waals (vdWs) heterostructures depends on electron–electron interactions and charge transfer at the hetero‐interface. However, what still remains to be unraveled is to which extent the carrier densities of both counterparts and the band alignment in the vdWs heterostructures determine the photoluminescence properties. Here, we systematically study the photoluminescence properties of monolayer MoS2/graphene heterostructures by modulating the carrier densities and contact barrier at the interface via electrochemical gating. It is shown that the PL intensities of excitons can be tuned by more than two orders of magnitude, and a blue‐shift of the exciton peak of up to 40 meV is observed. By extracting the carrier density of MoS2 using an electric potential distribution model, and the Schottky barrier using first‐principle calculations, we find that the controllable carrier density in MoS2 plays a dominant role in the PL tuning at negative gate bias, whereas the interlayer relaxation of excitons induced by the Schottky barrier has a major contribution at positive gate bias. This is further verified by controlling the tunneling barrier and screening field across MoS2 by inserting self‐assembled monolayers (SAMs) at the interface. These findings will benefit to better understand the effect of many‐body interactions and hetero‐interfaces on the optical and optoelectronic properties in vdWs heterostructures. Using monolayer MoS2/graphene heterostructures to construct electric double‐layer devices with an ion‐gels dielectric, the possibility of tuning the photoluminescence properties through electrochemical gating is realized. This tunability can be achieved by either modulating the carrier densities of the counterparts or the band alignment at the interface, and the dominant factor determining the PL tuning can be determined.
      PubDate: 2015-11-20T07:14:12.5945-05:00
      DOI: 10.1002/adfm.201503131
  • Semiconducting Carbon Nanotubes for Improved Efficiency and Thermal
           Stability of Polymer–Fullerene Solar Cells
    • Abstract: The effects of the incorporation of semiconducting single‐walled nanotubes (sc‐SWNTs) with high purity on the bulk heterojunction (BHJ) organic solar cell (OSC) based on regioregular poly(3‐hexylthiophene‐2,5‐diyl):[6,6]‐phenyl‐C61‐butyric acid methyl ester (rr‐P3HT:PCBM) are reported for the first time. The sc‐SWNTs induce the organization of the polymer phase, which is evident from the increase in crystallite size, the red‐shifted absorption characteristics and the enhanced hole mobility. By incorporating sc‐SWNTs, OSC with a power conversion efficiency (PCE) as high as 4% can be achieved, which is ≈8% higher than our best control device. A novel application of sc‐SWNTs in improving the thermal stability of BHJ OSCs is also demonstrated. After heating at 150 °C for 9 h, it is observed that the thermal stability of rr‐P3HT:PCBM devices improves by more than fivefold with inclusion of sc‐SWNTs. The thermal stability enhancement is attributed to a more suppressed phase separation, as shown by the remarkable decrease in the formation of sizeable crystals, which in turn can be the outcome of a more controlled crystallization of the blend materials on the nanotubes. Semiconducting single‐walled nanotubes (sc‐SWNTs) with high purity improve both device performance and thermal stability of organic solar cells based on a blend of a conjugated polymer and a fullerene derivative. The presence of sc‐SWNTs induces the organization of the polymer phase, while suppressing the excessive phase separation of the blend materials.
      PubDate: 2015-11-20T07:14:06.359708-05:
      DOI: 10.1002/adfm.201503256
  • A Transparent, Smooth, Thermally Robust, Conductive Polyimide for Flexible
    • Abstract: In this work, a thermally and mechanically robust, smooth transparent conductor composed of silver nanowires embedded in a colorless polyimide substrate is introduced. The polyimide is exceptionally chemically, mechanically, and thermally stable. While silver nanowire networks tend not to be thermally stable to high temperatures, the addition of a titania coating on the nano­wires dramatically increases their thermal stability. This allows for the polyimide to be thermally imidized at 360 °C with the silver nanowires in place, creating a smooth (
      PubDate: 2015-11-20T07:13:59.305849-05:
      DOI: 10.1002/adfm.201503342
  • Advanced Charged Sponge‐Like Membrane with Ultrahigh Stability and
           Selectivity for Vanadium Flow Batteries
    • Authors: Yuyue Zhao; Mingrun Li, Zhizhang Yuan, Xianfeng Li, Huamin Zhang, Ivo F. J. Vankelecom
      Abstract: Advanced charged sponge‐like porous membranes with ultrahigh stability and selectivity are designed and fabricated for vanadium flow battery (VFB) applications. The designed porous membranes are fabricated via constructing positively charged cross‐linked networks on the pore walls of polysulfone membranes. The charge density of the pore walls can be tuned by changing the crosslinking time. The positively charged pore walls can effectively retain vanadium ions via Donnan exclusion, hence keeping extremely high selectivity, while the crosslinked network effectively increases the membrane stability. As a result, the designed membranes exhibit an outstanding performance, combining extremely high selectivity and stability. The single cell assembled with the prepared porous membrane shows a columbic efficiency of 99% and an energy efficiency of 86% at a current density of 80 mA cm−2, which is much higher than Nafion 115 (93.5%; 82.3%). A battery assembled with the prepared membrane shows a stable battery performance over more than 6000 cycles, which is by far the longest record for porous membranes ever reported. These results indicate that advanced, charged, sponge‐like, porous membranes with a crosslinked pore‐wall structure are highly promising for VFB applications. A charged sponge‐like membrane with a pore‐wall covered imidazolium‐based crosslinked structure is designed and fabricated. The prepared membranes exhibit excellent selectivity and stability for vanadium flow battery application.
      PubDate: 2015-11-20T07:13:52.829829-05:
      DOI: 10.1002/adfm.201503390
  • Lightweight and Anisotropic Porous MWCNT/WPU Composites for Ultrahigh
           Performance Electromagnetic Interference Shielding
    • Authors: Zhihui Zeng; Hao Jin, Mingji Chen, Weiwei Li, Licheng Zhou, Zhong Zhang
      Abstract: Lightweight, flexible and anisotropic porous multiwalled carbon nanotube (MWCNT)/water‐borne polyurethane (WPU) composites are assembled by a facile freeze‐drying method. The composites contain extremely wide range of MWCNT mass ratios and show giant electromagnetic interference (EMI) shielding effectiveness (SE) which exceeds 50 or 20 dB in the X‐band while the density is merely 126 or 20 mg cm−3, respectively. The relevant specific SE is up to 1148 dB cm3 g−1, greater than those of other shielding materials ever reported. The ultrahigh EMI shielding performance is attributed to the conductivity of the cell walls caused by MWCNT content, the anisotropic porous structures, and the polarization between MWCNT and WPU matrix. In addition to the enhanced electrical properties, the composites also indicate enhanced mechanical properties compared with porous WPU and CNT architectures. Lightweight, flexible and anisotropic porous composites are assembled by a simple freeze‐drying method. The composites contain wide range of mass ratios of multiwalled carbon nanotube in water‐borne polyurethane matrix, and show giant electromagnetic interference shielding effectiveness, with the relevant specific shielding effectiveness greater than other shielding materials ever reported.
      PubDate: 2015-11-20T07:13:45.546129-05:
      DOI: 10.1002/adfm.201503579
  • High‐Performance Field Effect Transistors Using Electronic Inks of
           2D Molybdenum Oxide Nanoflakes
    • Abstract: Planar 2D materials are possibly the ideal channel candidates for future field effect transistors (FETs), due to their unique electronic properties. However, the performance of FETs based on 2D materials is yet to exceed those of conventional silicon based devices. Here, a 2D channel thin film made from liquid phase exfoliated molybdenum oxide nanoflake inks with highly controllable substoichiometric levels is presented. The ability to induce oxygen vacancies by solar light irradiation in an aqueous environment allows the tuning of electronic properties in 2D substoichiometric molybdenum oxides (MoO3−x). The highest mobility is found to be ≈600 cm2 V−1 s−1 with an estimated free electron concentration of ≈1.6 × 1021 cm−3 and an optimal IOn/IOff ratio of >105 for the FETs made of 2D flakes irradiated for 30 min (x = 0.042). These values are significant and represent a real opportunity to realize the next generation of tunable electronic devices using electronic inks. Electronic inks of 2D MoO3−x flakes based on a solar light irradiation in liquid‐phase exfoliated method are used for developing channels FETs for future high‐performance printed nanoelectronic devices. It is shown that the carrier concentration, energy band, and carrier charge mobility in 2D MoO3−x‐based FETs can be tuned and the optimal substoichiometric value with the maximum transconductance is obtained.
      PubDate: 2015-11-20T07:13:38.837004-05:
      DOI: 10.1002/adfm.201503698
  • Efficient Perovskite Hybrid Photovoltaics via Alcohol‐Vapor
           Annealing Treatment
    • Authors: Chang Liu; Kai Wang, Chao Yi, Xiaojun Shi, Adam W. Smith, Xiong Gong, Alan J. Heeger
      Abstract: In this work, alcohol‐vapor solvent annealing treatment on CH3NH3PbI3 thin films is reported, aiming to improve the crystal growth and increase the grain size of the CH3NH3PbI3 crystal, thus boosting the performance of perovskite photovoltaics. By selectively controlling the CH3NH3I precursor, larger‐grain size, higher crystallinity, and pinhole‐free CH3NH3PbI3 thin films are realized, which result in enhanced charge carrier diffusion length, decreased charge carrier recombination, and suppressed dark currents. As a result, over 43% enhanced efficiency along with high reproducibility and eliminated photocurrent hysteresis behavior are observed from perovskite hybrid solar cells (pero‐HSCs) where the CH3NH3PbI3 thin films are treated by methanol vapor as compared with that of pristine pero‐HSCs where the CH3NH3PbI3 thin films are without any alcohol vapor treatment. In addition, the dramatically restrained dark currents and raised photocurrents give rise to over ten times enhanced detectivities for perovskite hybrid photodetectors, reaching over 1013 cm Hz1/2 W−1 (Jones) from 375 to 800 nm. These results demonstrate that the method provides a simple and facile way to boost the device performance of perovskite photovoltaics. High performance of perovskite photovoltaics (perovskite solar cells and perovskite photodetectors) is realized by alcohol‐vapor solvent annealing treatment on CH3NH3PbI3 thin films to enhance the crystal growth and the grain size of the CH3NH3PbI3 crystals.
      PubDate: 2015-11-20T07:13:30.590998-05:
      DOI: 10.1002/adfm.201504041
  • Energy‐Level Alignment at the Organic/Electrode Interface in Organic
           Optoelectronic Devices
    • Authors: Zhanhao Hu; Zhiming Zhong, Yawen Chen, Chen Sun, Fei Huang, Junbiao Peng, Jian Wang, Yong Cao
      Abstract: It is commonly believed that the work‐function reduction effect of the cathode interfacial material in organic electronic devices leads to better energy‐level alignment at the organic/electrode interface, which enhances the device performance. However, there is no agreement on the exact dipole direction in the literature. In this study, a peel‐off method to reveal the buried organic/metal interface to examine the energy‐level alignment is developed. By splitting the device at different interfaces, it is discovered that oppositely oriented dipoles are formed at different surfaces of the interfacial layer. Moreover, the function of the electrode interface differs in different device types. In organic light‐emitting diodes, the vacuum‐level alignment generally occurs at the organic/cathode interface, while in organic photovoltaic devices, the Fermi‐level pinning commonly happens. Both are determined by the integer charge‐transfer levels of the organic materials and the work‐function of the electrode. As a result, the performance enhancement by the cathode interfacial material in organic photovoltaic devices cannot be solely explained by the energy‐level alignment. The clarification of the energy‐level alignment not only helps understand the device operation but also sets up a guideline to design the devices with better performance. There is no agreement on the dipole direction of the cathode interfacial layer in organic electronic devices in the literature. By splitting the device at different interfaces to study the energy‐level alignment, the energetic diagrams of the organic light‐emitting diode (OLED) and the organic photovoltaic (OPV) device are clarified. The vacuum level is aligned across the organic/metal interface in OLED, while energy pinning occurs in OPV.
      PubDate: 2015-11-19T09:42:30.177461-05:
      DOI: 10.1002/adfm.201503420
  • Rational Design of Small Molecules to Implement Organic Quaternary Memory
    • Authors: Qijian Zhang; Jinghui He, Hao Zhuang, Hua Li, Najun Li, Qingfeng Xu, Dongyun Chen, Jianmei Lu
      Abstract: Organic small‐molecule‐based devices with multilevel electroresistive memory behaviors have attracted more and more attentions due to their super‐high data‐storage density. However, up to now, only ternary memory molecules have been reported, and ternary storage devices may not be compatible with the binary computing systems perfectly. In this work, a donor–acceptor structured molecule containing three electron acceptors is rationally designed and the field‐induced charge‐transfer processes can occur from the donors. Organic quaternary memory devices based on this molecule are successfully demonstrated for the first time. The switching threshold voltages of the memory device are –2.04, –2.73, and –3.96 V, and the current ratio of the “0,” “1,” “2,” and “3” states is 1:101.78:103.47:105.36, which indicate a low possibility of read and write errors. The results represent a further step in organic high‐density data‐storage devices and will inspire the further study in this field. A donor–acceptor structured small molecule is rationally designed to contain three distinct electron acceptors. Organic quaternary memory behavior is demonstrated for the first time induced by a stepwise charge‐transfer process. The threshold voltages of the memory device are distinct, and the current ratio of the four states is identified, which indicate a low possibility of read and write errors.
      PubDate: 2015-11-19T09:42:26.749527-05:
      DOI: 10.1002/adfm.201503493
  • UV‐Light‐Driven Oxygen Pumping in a High‐Temperature
           Solid Oxide Photoelectrochemical Cell
    • Authors: Georg Christoph Brunauer; Bernhard Rotter, Gregor Walch, Esmaeil Esmaeili, Alexander Karl Opitz, Karl Ponweiser, Johann Summhammer, Juergen Fleig
      Abstract: A solid‐state photoelectrochemical cell is operated between 400 and 500 °C under 365 nm UV light. The cell consists of a photovoltaic part, based on a La0.8Sr0.2CrO3/SrTiO3 junction, and an electrochemical part including a zirconia solid electrolyte with a shared (La,Sr)FeO3 electrode. The photovoltaic cell part leads to open circuit voltages up to 920 mV at 400 °C. Upon UV light, this driving force is used in the electrochemical part of the cell to pump oxygen from low to high partial pressures, i.e., to convert radiation energy to chemical energy. This demonstrates the feasibility of high‐temperature photoelectrochemical cells for solar energy storage. The detailed characterization of the different resistance contributions in the system by DC and AC methods reveals the parts of the cell to be optimized for finally achieving high‐temperature photoelectrochemical water splitting. Photon‐driven electrochemical energy storage is realized by stacking a high‐temperature oxide‐based solar cell and a zirconia‐based oxygen pump. The solar cell part exhibits more than 900 mV cell voltage at 400 °C and this driving force is transferred to the electrochemical process by a shared electrode in the single stack device.
      PubDate: 2015-11-19T09:42:21.664969-05:
      DOI: 10.1002/adfm.201503597
  • Fast Photoresponse from 1T Tin Diselenide Atomic Layers
    • Authors: Peng Yu; Xuechao Yu, Wanglin Lu, Hsin Lin, Linfeng Sun, Kezhao Du, Fucai Liu, Wei Fu, Qingsheng Zeng, Zexiang Shen, Chuanhong Jin, Qi Jie Wang, Zheng Liu
      Abstract: Atomically layered 2D crystals such as transitional metal dichalcogenides (TMDs) provide an enchanting landscape for optoelectronic applications due to their unique atomic structures. They have been most intensively studied with 2H phase for easy fabrication and manipulation. 1T phase material could possess better electrocatalytic and photocatalytic properties, while they are difficult to fabricate. Herein, for the first time, the atomically layered 1T phase tin diselenides (SnSe2, III‐IV compound) are successfully exfoliated by the method of mechanical exfoliation from bulk single crystals, grown via the chemical vapor transport method without transport gas. More attractively, the high performance atomically layered SnSe2 photodetector has been first successfully fabricated, which displays a good responsivity of 0.5 A W−1 and a fast photoresponse down to ≈2 ms at room temperature, one of the fastest response times among all types of 2D photodetectors. It makes SnSe2 a promising candidate for high performance optoelectronic devices. Moreover, high performance bilayered SnSe2 field‐effect transistors are also demonstrated with a mobility of ≈4 cm2 V−1 s−1 and an on/off ratio of 103 at room temperature. The results demonstrate that few layered 1T TMD materials are relatively stable in air and can be exploited for various electrical and optical applications. A high performance atomically layered SnSe2 photodetector has been first successfully fabricated for the first time. The photodetector displays a good responsivity of 0.5 A W−1 and a fast photoresponse down to ≈2 ms at room temperature, one of the fastest response times among all types of 2D photodetectors.
      PubDate: 2015-11-19T09:42:16.866095-05:
      DOI: 10.1002/adfm.201503789
  • Bioprinting Complex Cartilaginous Structures with Clinically Compliant
    • Abstract: Bioprinting is an emerging technology for the fabrication of patient‐specific, anatomically complex tissues and organs. A novel bioink for printing cartilage grafts is developed based on two unmodified FDA‐compliant polysaccharides, gellan and alginate, combined with the clinical product BioCartilage (cartilage extracellular matrix particles). Cell‐friendly physical gelation of the bioink occurs in the presence of cations, which are delivered by co‐extrusion of a cation‐loaded transient support polymer to stabilize overhanging structures. Rheological properties of the bioink reveal optimal shear thinning and shear recovery properties for high‐fidelity bioprinting. Tensile testing of the bioprinted grafts reveals a strong, ductile material. As proof of concept, 3D auricular, nasal, meniscal, and vertebral disk grafts are printed based on computer tomography data or generic 3D models. Grafts after 8 weeks in vitro are scanned using magnetic resonance imaging and histological evaluation is performed. The bioink containing BioCartilage supports proliferation of chondrocytes and, in the presence of transforming growth factor beta‐3, supports strong deposition of cartilage matrix proteins. A clinically compliant bioprinting method is presented which yields patient‐specific cartilage grafts with good mechanical and biological properties. The versatile method can be used with any type of tissue particles to create tissue‐specific and bioactive scaffolds. Complex, cell‐laden cartilaginous structures are printed with regulatory‐compliant biomaterials. Printed grafts are tunable in mechanical properties and tissue‐specific, as they can contain extracellular matrix particles. Bioprinting of overhanging structures is achieved using a co‐extruded support polymer which also acts as a cation‐reservoir to rapidly crosslink the bioink.
      PubDate: 2015-11-19T03:17:32.688217-05:
      DOI: 10.1002/adfm.201503423
  • Solution‐Processed Crystalline n‐Type Organic Transistors
           Stable against Electrical Stress and Photooxidation
    • Authors: Hee Taek Yi; Zhihua Chen, Antonio Facchetti, Vitaly Podzorov
      Abstract: The field of organic electronics is still lacking ubiquitous organic transistors with an efficient electron (n‐type) transport that are environmentally and electrically robust. Here, solution‐processed n‐type N,N′‐1H,1H‐perfluorobutyldicyanoperylene‐carboxydi‐imide organic field‐effect transistors (OFETs) are reported and it is demonstrated that they are highly stable while operating both in vacuum and in the air at least up to temperatures as high as ≈100 °C. In addition, these crystalline thin‐film transistors are found to be resilient to photooxidation under intense illumination in oxygen atmosphere. The performance of these environmentally stable n‐type OFETs is on par with the commercial amorphous Si transistors: the highest electron mobility obtained in this study is μmax ≈ 0.6 cm2 V−1 s−1, while the average reproducible mobility is ⟨μ⟩ = 0.4 cm2 V−1 s−1. Importantly, no parasitic gate voltage VG sweep rate dependence of the nominal mobility in these devices is observed. In addition, the charge carrier mobility has been found to be temperature independent in the range T ≈ 250–373 K. The observed great operational stability and resilience against photooxidation, as well as a temperature‐independent mobility in these solution‐processed n‐type OFETs are beneficial for furthering practical applications of organic semiconductor devices. n‐type organic field‐effect transistors based on highly crystalline oriented N,N′‐1H,1H‐perfluorobutyldicyanoperylene‐carboxydi‐imide films grown from a solution are shown to have an excellent environmental and electrical stability, resistance to photooxidation, and the ability to withstand temperature cycling in a wide temperature range. The charge carrier mobility is found to be temperature independent in the practically relevant range between −25 and 100 °C.
      PubDate: 2015-11-17T10:38:50.7838-05:00
      DOI: 10.1002/adfm.201502423
  • Methods and Applications of Multilayer Silk Fibroin Laminates Based on
           Spatially Controlled Welding in Protein Films
    • Authors: Mark A. Brenckle; Benjamin Partlow, Hu Tao, Matthew B. Applegate, Andrew Reeves, Mark Paquette, Benedetto Marelli, David L. Kaplan, Fiorenzo G. Omenetto
      Abstract: Recent use of biopolymers as interface materials between planar, inorganic electronics and biological tissues has required the adaptation of micro‐ and nanofabrication techniques for use with these nontraditional materials. In this work, a method which builds on this principle for spatial control of adhesion in multilayer silk fibroin laminates is investigated. This is accomplished through the addition of a spatially patterned amorphous silk adhesive layer in between the films to be adhered, before thermally processing them with heat (120 °C) and pressure (80 Psi) according to established procedures. A one‐step method for rapid, high‐throughput fabrication is demonstrated, which establishes a strong (1100 kPa) bond between the layers independent of the initial processing conditions of the films. The adhesive layers can be patterned using existing silk fabrication techniques, allowing for the assembly of complex geometries including bilayers and microbubbles. Additionally, the utility of this method is demonstrated for potential applications in drug delivery and transient electronics. This approach provides a versatile method for construction of complex multilayer structures in silk, which with future work may ultimately improve the utility of this material as a bridge between high technology and the biomedical sciences. A thermal processing method for producing patterned multilayer laminates in silk fibroin is presented, based on thermal reflow of amorphous protein films. The method is able to produce laminates with strength on the order of the bulk material, and features as small as 100 μm. Applications of geometries produced by this method in bioelectronics and drug delivery are also presented.
      PubDate: 2015-11-17T10:38:47.541454-05:
      DOI: 10.1002/adfm.201502819
  • A Bio‐Inspired Rod‐Shaped Nanoplatform for Strongly Infecting
           Tumor Cells and Enhancing the Delivery Efficiency of Anticancer Drugs
    • Authors: Dan Li; Zhaomin Tang, Yuqian Gao, Huili Sun, Shaobing Zhou
      Abstract: The rapid clearance of circulating nanocarriers in blood during systemic drug delivery remains a challenging hurdle in cancer chemotherapy. Here, inspired by the unique features of bacterial pathogens, an original biodegradable polymer micellar system with a rod‐like shape similar to the morphology of bacterial pathogens is developed. These novel nanocarriers have excellent features such as a great capacity of overcoming the rapid clearance of reticuloendothelial system (RES) with long blood circulation, high cellular internalization, and enhanced therapeutic efficacy against cancers. In vivo pharmacokinetic studies in mice reveal that the rod‐like micelles of ≈40 nm in diameter and 600 nm in length possess a minimal uptake by the RES and excellent blood circulation half‐lives (t1/2β = 24.23 ± 2.87 h) for carrying doxorubicin in contrast to spheres (t1/2β = 8.39 ± 0.53 h). The antitumor activity of the rod‐shaped micelles in Balb/c mice bearing H22 tumor xenograft models reveals that they are promptly internalized by tumor cells, resulting in their superior potency and efficacy against artificial solid tumors. These findings suggest that the bio‐inspired nanocarriers as an emerging drug delivery platform may have considerable benefits for enhancing the delivery efficiency of anticancer drugs and in turn enhancing cancer therapy in future clinical applications. A novel bio‐inspired rod‐shaped micellar system is developed as a nanoplatform for highly effectively delivering anti­cancer drugs. The nanoplatform has a great capacity of escaping the rapid clearance of reticuloendothelial system in blood, a high internalization rate of tumor cells, and a significant enhancement of therapeutic agent potency against artificial solid tumors.
      PubDate: 2015-11-17T10:38:44.428314-05:
      DOI: 10.1002/adfm.201503664
  • Covalently Bonded Graphene–Carbon Nanotube Hybrid for
           High‐Performance Thermal Interfaces
    • Authors: Jie Chen; Jens H. Walther, Petros Koumoutsakos
      Abstract: The remarkable thermal properties of graphene and carbon nanotubes (CNTs) have been the subject of intensive investigations for the thermal management of integrated circuits. However, the small contact area of CNTs and the large anisotropic heat conduction of graphene have hindered their applications as effective thermal interface materials (TIMs). Here, a covalently bonded graphene–CNT (G‐CNT) hybrid is presented that multiplies the axial heat transfer capability of individual CNTs through their parallel arrangement, while at the same time it provides a large contact area for efficient heat extraction. Through computer simulations, it is demonstrated that the G‐CNT outperforms few‐layer graphene by more than 2 orders of magnitude for the c‐axis heat transfer, while its thermal resistance is 3 orders of magnitude lower than the state‐of‐the‐art TIMs. We show that heat can be removed from the G‐CNT by immersing it in a liquid. The heat transfer characteristics of G‐CNT suggest that it has the potential to revolutionize the design of high‐performance TIMs. An improvement for the c‐axis heat transfer of few layer graphene by a covalently bonded graphene–carbon nanotube (G‐CNT) hybrid is demonstrated. The G‐CNT exhibits a thermal resistance that is three orders of magnitude lower than state‐of‐the‐art thermal interface materials. The G‐CNT can be immersed in a circulating liquid for the ultrafast cooling of hot surfaces such as integrated circuits.
      PubDate: 2015-11-17T06:24:31.664729-05:
      DOI: 10.1002/adfm.201501593
  • Overcoming the Cut‐Off Charge Transfer Bandgaps at the PbS Quantum
           Dot Interface
    • Abstract: Light harvesting from large size of semiconductor PbS quantum dots (QDs) with a bandgap of less than 1 eV is one of the greatest challenges precluding the development of PbS QD‐based solar cells because the interfacial charge transfer (CT) from such QDs to the most commonly used electron acceptor materials is very inefficient, if it occurs at all. Thus, an alternative electron‐accepting unit with a new driving force for CT is urgently needed to harvest the light from large‐sized PbS QDs. Here, a cationic porphyrin is utilized as a new electron acceptor unit with unique features that bring the donor–acceptor components into close molecular proximity, allowing ultrafast and efficient electron transfer for QDs of all sizes, as inferred from the drastic photoluminescence quenching and the ultrafast formation of the porphyrin anionic species. The time‐resolved results clearly demonstrate the possibility of modulating the electron transfer process between PbS QDs and porphyrin moieties not only by the size quantization effect but also by the interfacial electrostatic interaction between the positively charged porphyrin and the negatively charged QDs. This approach provides a new pathway for engineering QD‐based solar cells that make the best use of the diverse photons making up the Sun's broad irradiance spectrum. The interfacial electrostatic interaction between the positively charged porphyrin and the negatively charged quantum dots (QDs) surface enables widening the effective bandgap (Eg) range for charge transfer (CT) from PbS QDs. For the first time, the occurance of an effective CT from large PbS QDs (Eg < 1 eV) is shown to positively charged porphyrin, thus overcoming the previously reported cut‐off CT bandgaps at PbS QD interface.
      PubDate: 2015-11-17T06:24:27.662775-05:
      DOI: 10.1002/adfm.201504035
  • Tunable Nanochannels along Graphene Oxide/Polymer Core–Shell
           Nanosheets to Enhance Proton Conductivity
    • Authors: Guangwei He; Chaoyi Chang, Mingzhao Xu, Shen Hu, Lingqiao Li, Jing Zhao, Zhen Li, Zongyu Li, Yongheng Yin, Mingyue Gang, Hong Wu, Xinlin Yang, Michael D. Guiver, Zhongyi Jiang
      Abstract: Simultaneous manipulation of topological and chemical structures to induce ionic nanochannel formation within solid electrolytes is a crucial but challenging task for the rational design of high‐performance electrochemical devices including proton exchange membrane fuel cell. Herein, a novel generic approach is presented for the construction of tunable ion‐conducting nanochannels via direct assembly of graphene oxide (GO)/poly(phosphonic acid) core–shell nanosheets prepared by surface‐initiated precipitation polymerization. Using this simple and rapid approach to engineer GO/polymer nanosheets at the molecular‐level, ordered and continuous nanochannels with interconnected hydrogen‐bonded networks having a favorable water environment can be created. The resulting membranes exhibit proton conductivities up to 32 mS cm−1 at 51% relative humidity, surpassing state‐of‐the‐art Nafion membrane and all previously reported GO‐based materials. A novel approach to construct tunable nanochannels via direct assembly of graphene oxide/polymer core–shell nanosheets is developed. Through molecular‐level engineering of the nanosheets, ordered and continuous nanochannels with well‐tailored chemical structures can be created. The resulting membrane exhibits a proton conductivity of 32 mS cm−1 at 51% RH, surpassing state‐of‐the‐art Nafion membrane and all previously reported GO‐based materials.
      PubDate: 2015-11-17T03:03:25.142157-05:
      DOI: 10.1002/adfm.201503229
  • Sol–Gel Assisted Inkjet Hologram Patterning
    • Authors: Aleksandr V. Yakovlev; Valentin. A. Milichko, Vladimir. V. Vinogradov, Alexandr V. Vinogradov
      Abstract: Hereby, it is presented for the first time a method of producing holographic text and images using inkjet printing. For this purpose, colorless TiO2 ink with a high refractive index is used and deposited on top of exposed poly(ethylene terephthalate)‐based microembossed paper by an inkjet printer. Nanoscale coating the paper containing printed text or graphics with transparent polymers or lacquers provides an optical effect of selective preservation of the holographic pattern. The resulting image is preserved only at the site of the colorless ink with a high refractive index from an inkjet printer, allowing to quickly generate any image with a holographic effect. Achieving these results has succeeded through the use of a colloidal dispersion of nanocrystalline titania with a refractive index of 1.75 ± 0.08 in the entire visible range, which meets inkjet rheological requirements. It is shown that the diffraction effect and optical transparency in the visible region are fully preserved. For the first time, it is demonstrated the importance of chemically prepared nanomaterials and nanostructures for an application in the field of holography. It is presented for the first time a method of producing holographic text and images using colorless TiO2 ink with a high ­refractive index is presented for the first time. The TiO2 ink is deposited on top of exposed PET‐based micro­embossed ­paper by an inkjet printer. The represented technology allows to quickly ­generate any image with a holographic effect.
      PubDate: 2015-11-17T03:03:18.380373-05:
      DOI: 10.1002/adfm.201503483
  • Metallic Architectures from 3D‐Printed Powder‐Based Liquid
    • Authors: Adam E. Jakus; Shannon L. Taylor, Nicholas R. Geisendorfer, David C. Dunand, Ramille N. Shah
      Abstract: A new method for complex metallic architecture fabrication is presented, through synthesis and 3D‐printing of a new class of 3D‐inks into green‐body structures followed by thermochemical transformation into sintered metallic counterparts. Small and large volumes of metal‐oxide, metal, and metal compound 3D‐printable inks are synthesized through simple mixing of solvent, powder, and the biomedical elastomer, polylactic‐co‐glycolic acid (PLGA). These inks can be 3D‐printed under ambient conditions via simple extrusion at speeds upwards of 150 mm s–1 into millimeter‐ and centimeter‐scale thin, thick, high aspect ratio, hollow and enclosed, and multi‐material architectures. The resulting 3D‐printed green‐bodies can be handled immediately, are remarkably robust, and may be further manipulated prior to metallic transformation. Green‐bodies are transformed into metallic counterparts without warping or cracking through reduction and sintering in a H2 atmosphere at elevated temperatures. It is shown that primary metal and binary alloy structures can be created from inks comprised of single and mixed oxide powders, and the versatility of the process is illustrated through its extension to more than two dozen additional metal‐based materials. A potential application of this new system is briefly demonstrated through cyclic reduction and oxidation of 3D‐printed iron oxide constructs, which remain intact through numerous redox cycles. Particle‐laden liquid inks are comprised of metals, metal oxides, and other metal compound powders. These inks are rapidly 3D‐printed into powder‐dense solids via simple extrusion to create the user‐defined architecture. Upon thermochemical processing in a reducing hydrogen atmosphere, the 3D‐printed objects reduce to metals, sinter, and result in a metallic architecture that maintains the as‐printed form without warping or cracking.
      PubDate: 2015-11-16T02:49:32.118332-05:
      DOI: 10.1002/adfm.201503921
  • Conjugated Polyelectrolyte Hybridized ZnO Nanoparticles as a Cathode
           Interfacial Layer for Efficient Polymer Light‐Emitting Diodes
    • Authors: Kyungmok Kim; Minwon Suh, Jihae Choi, Dongchan Lee, Youngsun Kim, Sang Hun Cheong, Donghyuk Kim, Duk Young Jeon
      Abstract: Alkoxy side‐chain tethered polyfluorene conjugated polyelectrolyte (CPE), poly[(9,9‐bis((8‐(3‐methyl‐1‐imidazolium)octyl)‐2,7‐fluorene)‐alt‐(9,9‐bis(2‐(2‐methoxyethoxy)ethyl)‐fluorene)] dibromide (F8imFO4), is utilized to obtain CPE‐hybridized ZnO nanoparticles (NPs) (CPE:ZnO hybrid NPs). The surface defects of ZnO NPs are passivated through coordination interactions with the oxygen atoms of alkoxy side‐chains and the bromide anions of ionic pendent groups from F8imFO4 to the oxygen vacancies of ZnO NPs, and thereby the fluorescence quenching at the interface of yellow‐emitting poly(p‐phenylene vinylene)/CPE:ZnO hybrid NPs is significantly reduced at the CPE concentration of 4.5 wt%. Yellow‐emitting polymer light‐emitting diodes (PLEDs) with CPE(4.5 wt%):ZnO hybrid NPs as a cathode interfacial layer show the highest device efficiencies of 11.7 cd A−1 at 5.2 V and 8.6 lm W−1 at 3.8 V compared to the ZnO NP only (4.8 cd A−1 at 7 V and 2.2 lm W−1 at 6.6 V) or CPE only (7.3 cd A−1 at 5.2 V and 4.9 lm W−1 at 4.2 V) devices. The results suggest here that the CPE:ZnO hybrid NPs has a great potential to improve the device performance of organic electronics. High‐efficiency polymer light‐emitting diodes (11.7 cd A−1 at 5.2 V and 8.6 lm W−1 at 3.8 V) are demonstrated using F8imFO4 conjugated polyelectrolyte (CPE)‐hybridized zinc oxide nano­particles (ZnO NPs) as a cathode interfacial layer. The alkoxy sidechains and bromide anions of F8imFO4 form a coordination bond to the ZnO surface, thus reducing fluorescence quenching of light‐emitting polymer.
      PubDate: 2015-11-10T11:01:17.230759-05:
      DOI: 10.1002/adfm.201502360
  • Structural and Electronic Properties of Crystalline, Isomerically Pure
           Anthradithiophene Derivatives
    • Authors: Rawad K. Hallani; Karl J. Thorley, Yaochuan Mei, Sean R. Parkin, Oana D. Jurchescu, John E. Anthony
      Abstract: Anthradithiophene chromophores are found in many current high‐performance organic semiconductors, even though these materials are typically synthesized as an inseparable mixture of syn and anti isomers. Recent syntheses of pure syn anthradithiophenes have shown no improvement in performance for the more homogeneous system, but similar studies on the pure anti isomer have not been reported. In this work, a simple protocol is described to prepare the pure anti isomer of fluorinated, functionalized anthradithiophenes, and perform detailed analysis of the intermolecular interactions in the crystal that yield increased density and closer chromophore contacts. Studies of the charge‐transport properties of these pure isomers, compared to the isomeric mixtures, suggest that the benefit of isomer purity is not consistent; in the syn case, there was minimal difference between the pure isomer and the mixture, while for the anti isomer mobility improved nearly twofold. Analysis of disorder in the crystals suggests a reason for this difference in performance. Isolation of pure anti anthradithiophene derivatives sheds light on the intermolecular interactions that increase order in these materials. Strong hydrogen–fluorine interactions, along with an inversion center in the pure anti isomer, reduces disorder and decrease intermolecular spacing in these derivatives, yielding field‐effect mobility higher than 6 cm2 V−1 s−1 in spin‐cast films.
      PubDate: 2015-11-10T11:01:12.677429-05:
      DOI: 10.1002/adfm.201502440
  • Rational Design of Polymeric Hybrid Micelles with Highly Tunable
           Properties to Co‐Deliver MicroRNA‐34a and Vismodegib for
           Melanoma Therapy
    • Authors: Hanmei Li; Yao Fu, Ting Zhang, Yanping Li, Xiaoyu Hong, Jiayu Jiang, Tao Gong, Zhirong Zhang, Xun Sun
      Abstract: A polymeric hybrid micelle (PHM) system with highly tunable properties is reported to co‐deliver small molecule and nucleic acid drugs for cancer therapy; this system is structurally simple and easy‐to‐fabricate. The PHM consists of two amphiphilic diblock copolymers, polycaprolactone‐polyethylenimine (PCL‐PEI) and polycaprolactone‐polyethyleneglycol (PCL‐PEG). PHMs are rationally designed with different physicochemical properties by simply adjusting the ratio of the two diblock copolymers and the near neutral PHM‐2 containing a low ratio of PCL‐PEI achieves the optimal balance between high tumor distribution and subsequent cellular uptake after intravenous injection. Encapsulating Hedgehog (Hh) pathway inhibitor vismodegib (VIS) and microRNA‐34a (miR‐34a) into PHM‐2 generates the VIS/PHM‐2/34a co‐delivery system. VIS/PHM‐2/34a shows synergistic anticancer efficacy in murine B16F10‐CD44+ cells, a highly metastatic tumor model of melanoma. VIS/PHM‐2/34a synergistically attenuates the expression of CD44, a vital receptor indicating the metastasis of melanoma. Intriguingly, inhibiting Hh pathway by VIS is accompanied by downregulation of CD44 expression, revealing that Hh signaling might be an upstream regulator of CD44 expression in melanoma. Thus, co‐delivery of miR‐34a and VIS demonstrates great potential in cancer therapy, and PHM offers a structurally simple and highly tunable platform for the co‐delivery of small molecule and nucleic acid drugs in tumor combination therapy. A polymeric hybrid micelle system with highly tunable properties is rationally designed and optimized to co‐deliver Hedgehog pathway inhibitor vismodegib and microRNA‐34a for melanoma therapy. The co‐delivery system shows synergistic anticancer efficacy on B16F10‐CD44+ cells in vitro and in vivo, indicating the potential of PHM in co‐delivery of small molecule and nucleic acid drugs.
      PubDate: 2015-11-10T11:01:08.056419-05:
      DOI: 10.1002/adfm.201503115
  • Thermally Stable Silver Nanowire–Polyimide Transparent Electrode
           Based on Atomic Layer Deposition of Zinc Oxide on Silver Nanowires
    • Authors: Dustin Chen; Jiajie Liang, Chao Liu, Gillian Saldanha, Fangchao Zhao, Kwing Tong, Jiang Liu, Qibing Pei
      Abstract: The performance of a flexible transparent conductive electrode with extremely smooth topography capable of withstanding thermal processing at 300 °C for at least 6 h with little change in sheet resistance and optical clarity is reported. In depth investigation is performed on atomic layer deposition (ALD) deposited ZnO on Ag nanowires (NWs) with regard to thermal and atmospheric corrosion stability. The ZnO coated nanowire networks are embedded within the surface of a polyimide matrix, and the
      PubDate: 2015-11-10T11:00:57.656206-05:
      DOI: 10.1002/adfm.201503236
  • Understanding the Origin of Li2MnO3 Activation in Li‐Rich Cathode
           Materials for Lithium‐Ion Batteries
    • Authors: Delai Ye; Guang Zeng, Kazuhiro Nogita, Kiyoshi Ozawa, Marlies Hankel, Debra J. Searles, Lianzhou Wang
      Abstract: Li‐rich layered cathode materials have been considered as a family of promising high‐energy density cathode materials for next generation lithium‐ion batteries (LIBs). However, although activation of the Li2MnO3 phase is known to play an essential role in providing superior capacity, the mechanism of activation of the Li2MnO3 phase in Li‐rich cathode materials is still not fully understood. In this work, an interesting Li‐rich cathode material Li1.87Mn0.94Ni0.19O3 is reported where the Li2MnO3 phase activation process can be effectively controlled due to the relatively low level of Ni doping. Such a unique feature offers the possibility of investigating the detailed activation mechanism by examining the intermediate states and phases of the Li2MnO3 during the controlled activation process. Combining powerful synchrotron in situ X‐ray diffraction analysis and observations using advanced scanning transmission electron microscopy equipped with a high angle annular dark field detector, it has been revealed that the subreaction of O2 generation may feature a much faster kinetics than the transition metal diffusion during the Li2MnO3 activation process, indicating that the latter plays a crucial role in determining the Li2MnO3 activation rate and leading to the unusual stepwise capacity increase over charging cycles. A Li‐rich cathode material Li1.87Mn0.94Ni0.19O3 with low level of Ni doping exhibits interersting slow activating process of Li2MnO3 phase, offering excellent platform to fundamentally understand the structural evolution of Li2MnO3 during activation. Detailed electrochemical study and in situ structure characterization reveals that the transition metal diffusion process features a much slower kinetics than O2 generation and determines the Li2MnO3 activation rate.
      PubDate: 2015-11-10T11:00:50.664392-05:
      DOI: 10.1002/adfm.201503276
  • Highly Efficient Solid‐State Near‐Infrared Emitting Material
           Based on Triphenylamine and Diphenylfumaronitrile with an EQE of 2.58% in
           Nondoped Organic Light‐Emitting Diode
    • Authors: Xiao Han; Qing Bai, Liang Yao, Haichao Liu, Yu Gao, Jinyu Li, Liqun Liu, Yulong Liu, Xiaoxiao Li, Ping Lu, Bing Yang
      Abstract: The development of efficient near‐infrared (NIR) emitting material is of current focus. Donor–acceptor (D–A) architecture has been proved to be an effective strategy to obtain narrow energy gap. Herein, a D–A‐type NIR fluorescent compound 2,3‐bis(4′‐(diphenylamino)‐[1,1′‐biphenyl]‐4‐yl)fumaronitrile (TPATCN) is synthesized and fully characterized. As revealed by theoretical calculations and photophysical experiments, TPATCN exerts the advantages of the relatively large dipole moment of the charge transfer state and a certain degree of orbital overlap of the local excited state. A highly mixed or hybrid local and charge transfer excited state might occur to simultaneously achieve both a large fraction of singlet formation and a high quantum efficiency in D–A system. TPATCN exhibits strong NIR fluorescence with the corresponding thin film quantum efficiency of 33% and the crystal efficiency of 72%. Remarkably, the external quantum efficiency of nondoped NIR organic light‐emitting diode (OLED) reaches 2.58% and remains fairly constant over a range of 100–300 mA cm−2, which is among the best results for NIR OLEDs reported so far. The development of near‐infrared (NIR) emitting material is of increasing interest. TPATCN with a strong NIR emission and a film efficiency of 33% is obtained. It benefits from a large dipole moment of CT state and a certain degree of orbital overlap of LE state. The maximum EQE of nondoped device reaches 2.58%, which is among the highest values of NIR OLEDs.
      PubDate: 2015-11-10T11:00:41.617783-05:
      DOI: 10.1002/adfm.201503344
  • Ultrahigh‐Performance Pseudocapacitor Electrodes Based on Transition
           Metal Phosphide Nanosheets Array via Phosphorization: A General and
           Effective Approach
    • Authors: Kai Zhou; Weijia Zhou, Linjing Yang, Jia Lu, Shuang Cheng, Wenjie Mai, Zhenghua Tang, Ligui Li, Shaowei Chen
      Abstract: In this study, a general and effective phosphorization strategy is successfully demonstrated to enhance supercapacitor performance of various transition metals oxide or hydroxide, such as Ni(OH)2, Co(OH)2, MnO2, and Fe2O3. For example, a 3D networked Ni2P nanosheets array via a facile phosphorization reaction of Ni(OH)2 nanosheets is grown on the surface of a Ni foam. The Ni foam‐supported Ni2P nanosheet (Ni2P NS/NF) electrode shows a remarkable specific capacitance of 2141 F g−1 at a scan rate of 50 mV s−1 and remains as high as 1109 F g−1 even at the current density of 83.3 A g−1. The specific capacitance is much larger than those of Ni(OH)2 NS/NF (747 F g−1 at 50 mV s−1). Furthermore, the electrode retains a high specific capacitance of 1437 F g−1 even after 5000 cycles at a current density of 10 A g−1, in sharp contrast with only 403 F g−1 of Ni(OH)2 NS/NF at the same current density. The similar enhanced performance is observed for Ni2P powder, which eliminates the influence of nickel foam. The enhanced supercapacitor performances are attributed to the 3D porous nanosheets network, enhanced conductivity, and two active components of Ni2+ and Pδ− with rich valences of Ni2P. Ultrahigh‐performance pseudocapacitor electrodes are prepared with a general and effective phosphorization strategy to enhance supercapacitor performance of various transition metals oxide or hydroxide. The Ni foam supported Ni2P nanosheets array electrode shows a remarkable specific capacitance of more than 3000 F g−1, much larger than the corresponding Ni(OH)2 nanosheets array before phosphorization.
      PubDate: 2015-11-10T11:00:32.214681-05:
      DOI: 10.1002/adfm.201503662
  • Stimuli‐Directing Self‐Organized 3D Liquid‐Crystalline
           Nanostructures: From Materials Design to Photonic Applications
    • Authors: Ling Wang; Quan Li
      Abstract: 3D photonic nanostructures with desirable functionalities in the visible light region and beyond have been recently given vast and increasing attentions because of the ability to control or confine electromagnetic waves in all three dimensions. Although substantial progress has been made in fabricating 3D nanostructures by means of lithography and nanotechnology, various bottlenecks still need to be overcome, and developing soft 3D stimuli‐directed nanostructures with tailored properties remains a challenging but exciting work. In this context, soft nanotechnology—i.e., exploiting self‐organized soft materials in nanotechnology—is emerging as a vibrant and burgeoning field of research in the bottom‐up nanofabrication of intelligent stimuli‐driven 3D photonic materials and devices. Liquid‐crystalline materials undoubtedly represent such a marvelous dynamic system that combines the liquid‐like fluidity and crystal‐like ordering from molecular to macroscopic material levels. Importantly, being “soft” makes the materials responsive to various stimuli such as temperature, light, mechanical force, and electric and magnetic fields as well as chemical and electrochemical reactions, resulting in a fascinating tunability of dynamic photonic bandgaps in the 3D nanostructure that provides numerous opportunities in all‐optical integrated circuits and next‐generation communication systems. Here, the development of 3D photonic nanostructures is reviewed, culminating with perspectives for the future scope and challenges of these emerging soft 3D photonic nanostructures towards device applications. Soft nanotechnology—i.e., exploiting self‐organized soft materials in nanotechnology—is emerging as an attractive paradigm in the bottom‐up nanofabrication of intelligent stimuli‐driven 3D photonic materials and devices. Liquid‐crystalline materials undoubtedly represent such an elegant dynamic system that combines the liquid‐like fluidity and crystal‐like ordering from molecular to macroscopic levels. This review provides a glimpse of the advancements in design, fabrication and applications of stimuli‐directing self‐organized 3D liquid‐crystalline photonic nanostructures.
      PubDate: 2015-11-09T11:58:23.475611-05:
      DOI: 10.1002/adfm.201502071
  • Tuning the Charge Transfer in Fx‐TCNQ/Rubrene Single‐Crystal
    • Abstract: Interfaces formed by two different organic semiconductors often exhibit a large conductivity, originating from transfer of charge between the constituent materials. The precise mechanisms driving charge transfer and determining its magnitude remain vastly unexplored, and are not understood microscopically. To start addressing this issue, we have performed a systematic study of highly reproducible single‐crystal interfaces based on rubrene (tetraphenylnaphthacene) and Fx‐TCNQ (fluorinated tetracyanoquinodimethane), a family of molecules whose electron affinity can be tuned by increasing the fluorine content. The combined analysis of transport and scanning Kelvin probe measurements reveals that the interfacial charge‐carrier density, resistivity, and activation energy correlate with the electron affinity of Fx‐TCNQ crystals, with a higher affinity resulting in larger charge transfer. Although the transport properties can be described consistently and quantitatively using a mobility‐edge model, we find that a quantitative analysis of charge transfer in terms of single‐particle band diagrams reveals a discrepancy ≈100 meV in the interfacial energy level alignment. We attribute the discrepancy to phenomena known to affect the energetics of organic semiconductors, which are neglected by a single‐particle description—such as molecular relaxation and bandgap renormalization due to screening. The systematic behavior of the Fx‐TCNQ/rubrene interfaces opens the possibility to investigate these phenomena experimentally, under controlled conditions. Using the family of Fx‐TCNQ molecules, the first comparative study is performed on organic single‐crystal charge‐transfer interfaces. The very systematic behavior of the studied interfaces now opens the possibility of investigating the microscopic charge‐transfer mechanisms experimentally under controlled conditions.
      PubDate: 2015-11-09T11:58:07.262032-05:
      DOI: 10.1002/adfm.201502082
  • High‐Performance Supercapacitor Applications of
           NiO‐Nanoparticle‐Decorated Millimeter‐Long Vertically
           Aligned Carbon Nanotube Arrays via an Effective Supercritical
           CO2‐Assisted Method
    • Authors: Junye Cheng; Bin Zhao, Wenkang Zhang, Feng Shi, Guangping Zheng, Deqing Zhang, Junhe Yang
      Abstract: Nickel oxide (NiO) nanoparticles are distributed uniformly in the vertically aligned carbon nanotube arrays (VACNTs) with millimeter thickness by an effective supercritical carbon dioxide‐assisted method. The as‐prepared VACNT/NiO hybrid structures are used as electrodes without binders and conducting additives for supercapacitor applications. Due to the synergetic effects of NiO and VACNTs with nanoporous structures and parallel 1D conductive paths for electrons, the supercapacitors exhibit a high capacitance of 1088.44 F g−1. Furthermore, an asymmetric supercapacitor is assembled using the as‐synthesized VACNTs/NiO hybrids as the positive electrode and the VACNTs as the negative electrode. Remarkably, the energy density of the asymmetric supercapacitor is as high as 90.9 Wh kg−1 at 3.2 kW kg−1 and the maximum power density reaches 25.6 kW kg−1 at 24.9 Wh kg−1, which are superior to those of the NiO or VACNTs‐based asymmetric supercapacitors. More importantly, the asymmetric supercapacitors exhibit capacitance retention of 87.1% after 2000 cycles at 5 A g−1. The work provides a novel approach in decorating highly dense and long VACNTs with active materials, which are promising electrodes for supercapacitors with ultrahigh power density and energy density. An effective supercritical CO2‐assisted approach is presented for synthesizing vertically aligned carbon nanotube (VACNT)/NiO hybrid structures. NiO nanoparticles are distributed uniformly in the highly dense, millimeter‐long VACNTs. The unique hybrid structures of VACNT/NiO exhibit high capacity and long cycle stability. The great electrochemical properties of the VACNT/NiO hybrid materials plus their simple fabrication make this class of materials attractive for supercapacitor applications.
      PubDate: 2015-11-09T11:58:04.129514-05:
      DOI: 10.1002/adfm.201502711
  • Water‐Powered Cell‐Mimicking Janus Micromotor
    • Abstract: Cell derivatives have received increasing attention due to their unique ability to mimic many of the natural properties displayed by their source cells. Integration of cell‐derived natural materials with synthetic subjects can be applied toward the development of novel biomedical nano/microscale devices for a wide range of applications, including drug delivery and biodetoxification. Herein, a cell membrane functionalized magnesium‐based Janus micromotor, powered by water, that mimics natural motile cells is reported. The new cell‐mimicking Janus micromotor is constructed by integrating red blood cell (RBC) membranes, gold nanoparticles (AuNPs), and alginate (ALG) onto the exposed surface areas of magnesium microparticles that are partially embedded in Parafilm. The resulting RBC membrane‐coated magnesium (RBC‐Mg) Janus micromotors display an efficient and guided propulsion in water without any external fuel, as well as in biological (albumin‐rich) media with no apparent biofouling, mimicking the movement of natural motile cells. The effective RBC membrane coating bestows the RBC‐Mg Janus micromotors with unique capability for absorbing and neutralizing both biological protein toxins and nerve agent simulants. Such detoxification ability is facilitated greatly by the water‐driven motion of the motors. The RBC‐Mg Janus micromotors represent an exciting progress toward cell‐mimicking microscale motors that hold great promise for diverse biomedical and biodefense applications. Cell‐mimicking Janus micromotors are con­­structed by integrating red blood cell (RBC) membranes and gold nanoparticles onto the exposed surface areas of magnesium microparticles to achieve effi­cient water‐driven propulsion and rapid detoxification in biological matrices. The RBC‐Mg Janus micromotors represent an exciting progress toward cell‐mimicking microscale motors that hold considerable promise for diverse biomedical and biodefense applications.
      PubDate: 2015-11-09T11:57:57.631619-05:
      DOI: 10.1002/adfm.201503441
  • Nanoporous Substrate‐Infiltrated Hydrogels: a Bioinspired
           Regenerable Surface for High Load Bearing and Tunable Friction
    • Authors: Shuanhong Ma; M. Scaraggi, Daoai Wang, Xiaolong Wang, Yongmin Liang, Weimin Liu, Daniele Dini, Feng Zhou
      Abstract: Nature has successfully combined soft matter and hydration lubrication to achieve ultralow friction even at relatively high contact pressure (e.g., articular cartilage). Inspired by this, hydrogels are used to mimic natural aqueous lubricating systems. However, hydrogels usually cannot bear high load because of solvation in water environments and are, therefore, not adopted in real applications. Here, a novel composite surface of ordered hydrogel nanofiber arrays confined in anodic aluminum oxide (AAO) nanoporous template based on a soft/hard combination strategy is developed. The synergy between the soft hydrogel fibers, which provide excellent aqueous lubrication, and the hard phase AAO, which gives high load bearing capacity, is shown to be capable of attaining very low coeffcient of friction (0.3) and superlubrication (≈10−3) when their state is changed from contracted to swollen by means of acidic and basic actuation. The mechanisms governing ultralow and tunable friction are theoretically explained via an in‐depth study of the chemomechanical interactions responsible for the behavior of these substrate‐infiltrated hydrogels. These findings open a promising route for the design of ultra‐slippery and smart surface/interface materials. A novel composite surface of ordered nanohydrogel arrays confined in an anodic aluminum oxide template based on a soft/hard combination strategy is reported. The surface shows a low friction coefficient (0.3) and superlubrication (≈10−3) by acidic and basic actuation.
      PubDate: 2015-11-09T11:57:54.865628-05:
      DOI: 10.1002/adfm.201503681
  • Regimes of Exciton Transport in Molecular Crystals in the Presence of
           Dynamic Disorder
    • Abstract: Thermal motions in molecular crystals cause substantial fluctuation of the excitonic coupling between neighboring molecules (dynamic disorder). The effect of such fluctuation on the exciton dynamics in two limiting cases is explored here, exemplified by the crystals of anthracene and a heteropentacene derivative. When the excitonic coupling is small in comparison with the electron–phonon coupling, the exciton diffusion is incoherent and the inclusion of excitonic coupling fluctuation does not alter the exciton physics but can improve the agreement between computed and experimental diffusion coefficients. For large excitonic couplings, when the transport becomes coherent, the thermal motions determine the diffusivity of the exciton, which can be several orders of magnitude larger than in the incoherent case. The coherent regime is less frequent but potentially of great technological importance. Thermal motions in molecular crystals cause substantial fluctuation of the excitonic coupling between neighboring molecules (dynamic disorder) and, thus, the role of this fluctuation on the exciton dynamics is explored in two extreme regimes (incoherent and coherent) by means of two crystal models, anthracene and a heteropentacene derivative.
      PubDate: 2015-11-09T11:57:48.255391-05:
      DOI: 10.1002/adfm.201503888
  • All‐Carbon Nanoarchitectures as High‐Performance Separation
           Membranes with Superior Stability
    • Authors: Kunli Goh; Wenchao Jiang, Huseyin Enis Karahan, Shengli Zhai, Li Wei, Dingshan Yu, Anthony G. Fane, Rong Wang, Yuan Chen
      Abstract: The application of graphene‐based membranes is hindered by their poor stability under practical hydrodynamic conditions. Here, nanocarbon architectures are designed by intercalating surface‐functionalized, small‐diameter, multi‐walled carbon nanotubes (MWCNTs) into reduced graphene oxide (rGO) sheets to create highly stable membranes with improved water permeability and enhanced membrane selectivity. With the intercalation of 10 nm diameter MWCNTs, the water permeability reaches 52.7 L m−2 h−1 bar−1, which is 4.8 times that of pristine rGO membrane and five to ten times higher than most commercial nanofiltration membranes. The membrane also attains almost 100% rejection for three organic dyes of different charges. More importantly, the membrane can endure a turbulent hydrodynamic flow with cross‐flow rates up to 2000 mL min−1 and a Reynolds number of 4667. Physicochemical characterization reveals that the inner graphitic walls of the MWCNTs can serve as spacers, while nanoscale rGO foliates on the outer walls interconnect with the assimilated rGO sheets to instill superior membrane stability. In contrast, intercalating with single‐walled nanotubes fails to reproduce such stability. Overall, this nanoarchitectured design is highly versatile in creating both graphene‐rich and CNT‐rich all‐carbon membranes with engineered nanochannels, and is regarded as a general approach in obtaining stable membranes for realizing practical applications of graphene‐based membranes. All‐carbon nanoarchitectured membranes comprising reduced graphene oxide and multi‐walled carbon nanotubes exhibit a high water permeability, which is five to ten times higher than most commercial nanofiltration membranes. The membranes show almost 100% organic dye rejection and, most importantly, superior membrane stability under a turbulent hydrodynamic flow condition of 2000 mL min−1 and a Reynolds number of 4667.
      PubDate: 2015-11-06T11:12:35.811759-05:
      DOI: 10.1002/adfm.201502955
  • Enhanced Antitumor Efficacy by 808 nm Laser‐Induced Synergistic
           Photothermal and Photodynamic Therapy Based on a
           Indocyanine‐Green‐Attached W18O49 Nanostructure
    • Authors: Kerong Deng; Zhiyao Hou, Xiaoran Deng, Piaoping Yang, Chunxia Li, Jun Lin
      Abstract: A novel nanoplatform based on tungsten oxide (W18O49, WO) and indocyanine green (ICG) for dual‐modal photothermal therapy (PTT) and photodynamic therapy (PDT) has been successfully constructed. In this design, the hierarchical unique nanorod‐bundled W18O49 nanostructures play roles in being not only as an efficient photothermal agent for PTT but also as a potential nanovehicle for ICG molecules via electrostatic adsorption after modified with trimethylammonium groups on their surface. It is found that the ability of ICG to produce cytotoxic reactive oxygen species for PDT is well maintained after being attached on the WO, thus the as‐obtained WO@ICG can achieve a synergistic effect of combined PTT and PDT under single 808 nm near‐infrared (NIR) laser excitation. Notably, compared with PTT or PDT alone, the enhanced HeLa cells lethality of the 808 nm laser triggered dual‐modal therapy is observed. The in vivo animal experiments have shown that WO@ICG has effective solid tumor ablation effect with 808 nm NIR light irradiation, revealing the potential of these nanocomposites as a NIR‐mediated dual‐modal therapeutic platform for cancer treatment. An 808‐nm‐light‐mediated, antitumor, synergistic photothermal and photodynamic therapy nanosystem based on tungsten oxide@indocyanine green (WO@ICG) nanocomposites has been successfully constructed. These WO@ICG nanocomposites exhibit fascinating in vitro and in vivo dual‐modal phototherapeutic properties under single 808 nm light irradiation, including therapeutic potential in cultured HeLa cells and HeLa tumor‐bearing mice.
      PubDate: 2015-11-06T11:12:24.480084-05:
      DOI: 10.1002/adfm.201503046
  • Self‐Supported Cobalt Phosphide Mesoporous Nanorod Arrays: A
           Flexible and Bifunctional Electrode for Highly Active Electrocatalytic
           Water Reduction and Oxidation
    • Abstract: Water splitting for the production of hydrogen and oxygen is an appealing solution to advance many sustainable and renewable energy conversion and storage systems, while the key fact depends on the innovative exploration regarding the design of efficient electrocatalysts. Reported herein is the growth of CoP mesoporous nanorod arrays on conductive Ni foam through an electrodeposition strategy. The resulting material of well‐defined mesoporosity and a high specific surface area (148 m2 g−1) can be directly employed as a bifunctional and flexible working electrode for both hydrogen and oxygen evolution reactions, showing superior activities as compared with noble metal benchmarks and state‐of‐the‐art transition‐metal‐based catalysts. This is intimately related to the unique nanorod array electrode configuration, leading to excellent electric interconnection and improved mass transport. A further step is taken toward an alkaline electrolyzer that can achieve a current density of 10 mA cm−2 at a voltage around 1.62 V over a long‐term operation, better than the combination of Pt and IrO2. This development is suggested to be readily extended to obtain other electrocatalysis systems for scale‐up water‐splitting technology. Flexible, bifunctional electrodes with self‐supported CoP mesoporous nanorod arrays are fabricated through an electrodeposition strategy. The electrodes possess well‐structured mesoporosity and a high specific surface area, exhibiting high activities toward both electrochemical hydrogen and oxygen evolution reactions. In a further step, an alkaline electrolyzer with a current density of 10 mA cm−2 at 1.62 V in a long‐term operation is realized.
      PubDate: 2015-11-06T11:12:17.107137-05:
      DOI: 10.1002/adfm.201503666
  • Humidity‐Triggered Self‐Healing of Microporous Polyelectrolyte
           Multilayer Coatings for Hydrophobic Drug Delivery
    • Abstract: Layer‐by‐layer (LbL) self‐assemblies have inherent potential as dynamic coatings because of the sensitivity of their building blocks to external stimuli. Here, humidity serves as a feasible trigger to activate the self‐healing of a microporous polyethylenimine/poly(acrylic acid) multilayer film. Microporous structures within the polyelectrolyte multilayer (PEM) film are created by acid treatment, followed by freeze‐drying to remove water. The self‐healing of these micropores can be triggered at 100% relative humidity, under which condition the mobility of the polyelectrolytes is activated. Based on this, a facile and versatile method is suggested for directly integrating hydrophobic drugs into PEM films for surface‐mediated drug delivery. The high porosity of microporous film enables the highest loading (≈303.5 μg cm−2 for a 15‐bilayered film) of triclosan to be a one‐shot process via wicking action and subsequent solvent removal, thus dramatically streamlining the processes and reducing complexities compared to the existing LbL strategies. The self‐healing of a drug‐loaded microporous PEM film significantly reduces the diffusion coefficient of triclosan, which is favorable for the long‐term sustained release of the drug. The dynamic properties of this polymeric coating provide great potential for its use as a delivery platform for hydrophobic drugs in a wide variety of biomedical applications. Humidity can serve as a feasible trigger to activate the self‐healing of microporous polyelectrolyte multilayer film. Based on this, a facile and versatile means is suggested to directly integrate hydrophobic drugs into the films for biomedical coatings.
      PubDate: 2015-11-05T09:31:31.511577-05:
      DOI: 10.1002/adfm.201503258
  • A Dual‐FRET‐Based Versatile Prodrug for Real‐Time Drug
           Release Monitoring and In Situ Therapeutic Efficacy Evaluation
    • Abstract: A dual‐Förster resonance energy transfer (FRET)‐based versatile prodrug (V‐prodrug), in which the fluorescence of both 5(6)‐carboxylfluorescein (FAM) and doxorubicin (DOX) can be quenched by 4‐(dimethylaminoazo)benzene‐4‐carboxylic acid (Dabcyl) with high quenching efficiency, is developed in this paper. The V‐prodrug can selectively bind to the αvβ3 integrin overexpressed cancer cells through the Arg‐Gly‐Asp (RGD) targeting moiety. After that, the acid‐mediated DOX release of the V‐prodrug can be real‐time monitored by the increase of the red fluorescence from DOX. Thereafter, DOX‐induced cell apoptosis can also be in situ assessed by the fluorescence recovery of the FAM, due to the caspase‐3‐mediated Asp‐Glu‐Val‐Asp (DEVD) peptide sequence cleavage. This novel prodrug provides a cascaded imaging of real‐time drug release and subsequent cell apoptosis, which enables the in situ detection of the cancer response and the therapeutic efficacy evaluation of the prodrug. A dual‐Förster resonance energy transfer (FRET)‐based versatile prodrug (V‐prodrug) is designed to provide a cascaded imaging of real‐time drug release and subsequent cell apoptosis. This V‐prodrug enables the in situ detection of the cancer response as well as the therapeutic efficacy evaluation of the drug.
      PubDate: 2015-11-05T09:31:19.143792-05:
      DOI: 10.1002/adfm.201503262
  • Flash‐Assisted Processing of Highly Conductive Zinc Oxide Electrodes
           from Water
    • Authors: Enrico Della Gaspera; Danielle F. Kennedy, Joel van Embden, Anthony S. R. Chesman, Thomas R. Gengenbach, Karl Weber, Jacek J. Jasieniak
      Abstract: Fabricating high‐quality transparent conductors using inexpensive and industrially viable techniques is a major challenge toward developing low cost optoelectronic devices such as solar cells, light emitting diodes, and touch panel displays. In this work, highly transparent and conductive ZnO thin films are prepared from a low‐temperature, aqueous deposition method through the careful control of the reaction chemistry. A robotic synthetic platform is used to explore the wide parameter space of a chemical bath system that uses only cheap and earth abundant chemicals for thin film deposition. As‐deposited films are found to be highly resistive, however, through exposure to several millisecond pulses of high‐intensity, broadband light, intrinsically doped ZnO films with sheet resistances as low as 40 Ω □−1 can be readily prepared. Such values are comparable with state‐of‐the‐art‐doped transparent conducting oxides. The mild processing conditions (
      PubDate: 2015-11-05T09:31:10.212243-05:
      DOI: 10.1002/adfm.201503421
  • Flexible Asymmetric Supercapacitor Based on Structure‐Optimized
           Mn3O4/Reduced Graphene Oxide Nanohybrid Paper with High Energy and Power
    • Authors: Yating Hu; Cao Guan, Guangxue Feng, Qingqing Ke, Xiaolei Huang, John Wang
      Abstract: A highly flexible Mn3O4/reduced graphene oxide (rGO) nanohybrid paper with high electrical conductivity and high mass loading of Mn3O4 nanofibers (0.71 g cm−3) is developed via a facile gel formation and electrochemical reduction process, which is low‐cost, environmental friendly, and easy to scale up. Confined Mn3O4 nanofibers are well dispersed within the rGO sheets, which demonstrate to be a promising cathode material for flexible asymmetric supercapacitors (ASCs). When coupled with an electrochemically reduced rGO paper as the anode, a flexible ASC device, based on the Mn3O4/rGO nanohybrid paper as the cathode, is assembled; and it demonstrates remarkable electrochemical performance: a high volumetric capacitance of 54.6 F cm−3 (546.05 mF cm−2), and remarkable volumetric energy and power density (0.0055 Wh cm−3 and 10.95 W cm−3) being achieved with excellent cycling ability. The nanohybrid paper shows great improvement for flexible energy devices in terms of electrochemical properties. A highly flexible Mn3O4/reduced graphene oxide (rGO) nanohybrid paper with high electrical conductivity and high mass loading of Mn3O4 nanofiber (0.71 g cm−3) is successfully developed via a facile gel formation and electrochemical reduction process. Through this novel design and processing control, the energy and power density of the flexible Mn3O4/rGO‐based asymmetric supercapacitor are greatly improved.
      PubDate: 2015-11-05T09:26:40.312772-05:
      DOI: 10.1002/adfm.201503528
  • Polydopamine as a Biocompatible Multifunctional Nanocarrier for Combined
           Radioisotope Therapy and Chemotherapy of Cancer
    • Authors: Xiaoyan Zhong; Kai Yang, Zhiliang Dong, Xuan Yi, Yong Wang, Cuicui Ge, Yuliang Zhao, Zhuang Liu
      Abstract: Development of biodegradable nanomaterials for drug delivery and cancer theranostics has attracted great attention in recent years. In this work, polydopamine (PDA), a biocompatible polymer, is developed as a promising carrier for loading of both radionuclides and an anticancer drug to realize nuclear‐imaging‐guided combined radioisotope therapy (RIT) and chemotherapy of cancer in one system. It is found that PDA nanoparticles after modification with poly(ethylene glycol) (PEG) can successfully load several different radionuclides such as 99mTc and 131I, as well as an anticancer drug doxorubicin (DOX). While labeling PDA‐PEG with 99mTc (99mTc‐PDA‐PEG) enables in vivo single photon emission computed tomography imaging, nanoparticles co‐loaded with 131I and DOX (131I‐PDA‐PEG/DOX) can be utilized for combined RIT and chemotherapy, which offers effective cancer treatment efficacy in a remarkably synergistic manner, without rendering significant toxicity to the treated animals. Therefore, this study presents an interesting class of biocompatible nanocarriers, which allow the combination of RIT and chemotherapy, the two extensively applied cancer therapeutic strategies, promising for future clinic translations in cancer treatment. Ploydopamine (PDA) nanoparticles as a biocompatible nanocarrier platform are developed for loading of both radionuclides and an anticancer drug to realize nuclear‐imaging‐guided combined radioisotope therapy and chemotherapy of cancer. Utilizing this synergistic manner, 131I‐PDA‐poly(ethylene glycol)/doxorubicin nanoparticles exhibited effective cancer treatment efficacy, without rendering significant toxicity to the treated animals.
      PubDate: 2015-11-05T09:26:31.941346-05:
      DOI: 10.1002/adfm.201503587
  • Dual‐Salt Mg‐Based Batteries with Conversion Cathodes
    • Authors: Ye Zhang; Junjie Xie, Yanlin Han, Chilin Li
      Abstract: Mg batteries as the most typical multivalent batteries are attracting increasing attention because of resource abundance, high volumetric energy density, and smooth plating/stripping of Mg anodes. However, current limitations for the progress of Mg batteries come from the lack of high voltage electrolytes and fast Mg‐insertable structure prototypes. In order to improve their energy or power density, hybrid systems combining Li‐driven cathode reaction with Mg anode process appear to be a potential solution by bypassing the aforementioned limitations. Here, FeS x (x = 1 or 2) is employed as conversion cathode with 2–4 electron transfers to achieve a maximum energy density close to 400 Wh kg−1, which is comparable with that of Li‐ion batteries but without serious dendrite growth and polysulphide dissolution. In situ formation of solid electrolyte interfaces on both sulfide and Mg electrodes is likely responsible for long‐life cycling and suppression of S‐species passivation at Mg anodes. Without any decoration on the cathode, electrolyte additive, or anode protection, a reversible capacity of more than 200 mAh g−1 is still preserved for Mg/FeS2 after 200 cycles. In Mg/Li hybrid battery systems with Mg anodes, FeS x (x = 1 or 2) is employed as conversion cathodes. With 2–4 electron transfers these systems achieve a maximum energy density close to 400 Wh kg−1 without serious dendrite growth and polysulfide dissolution.
      PubDate: 2015-11-05T09:26:26.214179-05:
      DOI: 10.1002/adfm.201503639
  • Nonvolatile Floating‐Gate Memories Based on Stacked Black
           Phosphorus–Boron Nitride–MoS2 Heterostructures
    • Authors: Dong Li; Xiaojuan Wang, Qichong Zhang, Liping Zou, Xiangfan Xu, Zengxing Zhang
      Abstract: Research on van der Waals heterostructures based on stacked 2D atomic crystals is intense due to their prominent properties and potential applications for flexible transparent electronics and optoelectronics. Here, nonvolatile memory devices based on floating‐gate field‐effect transistors that are stacked with 2D materials are reported, where few‐layer black phosphorus acts as channel layer, hexagonal boron nitride as tunnel barrier layer, and MoS2 as charge trapping layer. Because of the ambipolar behavior of black phosphorus, electrons and holes can be stored in the MoS2 charge trapping layer. The heterostructures exhibit remarkable erase/program ratio and endurance performance, and can be developed for high‐performance type‐switching memories and reconfigurable inverter logic circuits, indicating that it is promising for application in memory devices completely based on 2D atomic crystals. Nonvolatile ambipolar memory devices are developed based on stacked black phosphorus–boron nitride–molybdenum disulphide heterostructure floating‐gate field‐effect transistors. The memory device exhibits a fairly large memory window with a width (ΔV) of ≈60 V for a maximum control gate voltage of 40 V and can be switched well between the erase and program state.
      PubDate: 2015-11-05T09:26:18.400122-05:
      DOI: 10.1002/adfm.201503645
  • Microfluidic‐Spinning‐Directed Microreactors Toward Generation
           of Multiple Nanocrystals Loaded Anisotropic Fluorescent Microfibers
    • Abstract: Anisotropic fluorescent hybrid microfibers with distinct optical properties and delicate architectures have aroused special interest because of their potential applications in tissue engineering, drug delivery, sensors, and functional textiles. Microfluidic systems have provided an ideal microreactor platform to produce anisotropic fibers due to their simplified manipulation, high efficiency, flexible controllability, and environmental‐friendly chemical process. Here a novel microfiber reactor based on a microfluidic spinning technique for in situ fabrication of nanocrystals loaded anisotropic fluorescent hybrid microfibers is demonstrated. Multiple nanocrystal reactions are carried out in coaxial flow‐based microdevices with different geometric features, and various nanocrystals loaded microfibers with solid, string‐of‐beads and Janus topographies are obtained. Moreover, the resulted anisotropic fluorescent hybrid microfibers present multiple optical signals. This strategy contributes a facile and environmental‐friendly route to anisotropic fluorescent hybrid microfibers and might open a promising avenue to multiplex optical sensing materials. A fiber microreactor based on a microfluidic spinning technique is proposed for the in situ fabrication of nanocrystals loaded anisotropic fluorescent hybrid microfibers. By designing coaxial flow microdevices with different geometric features, multiple nanocrystal reactions in microreactors result in microfibers with delicate topographies and distinct optical properties. This work develops a facile platform for rapid fabrication of anisotropic fluorescent hybrid microfibers.
      PubDate: 2015-11-05T09:26:15.898995-05:
      DOI: 10.1002/adfm.201503680
  • Highly Flexible Transparent Electrodes Containing Ultrathin Silver for
           Efficient Polymer Solar Cells
    • Abstract: Transparent electrodes (TEs) having electrooptical trade‐offs better than state‐of‐the‐art indium tin oxide (ITO) are continuously sought as they are essential to enable flexible electronic and optoelectronic devices. In this work, a TiO2‐Ag‐ITO (TAI)‐based TE is introduced and its use is demonstrated in an inverted polymer solar cell (I‐PSCs). Thanks to the favorable nucleation and wetting conditions provided by the TiO2, the ultrathin silver film percolates and becomes continuous with high smoothness at very low thicknesses (3–4 nm), much lower than those required when it is directly deposited on a plastic or glass substrate. Compared to conventional ITO‐TE, the proposed TAI‐TE exhibits exceptionally lower electrical sheet resistance (6.2 Ω sq−1), higher optical transmittance, a figure‐of‐merit two times larger, and mechanical flexibility, the latter confirmed by the fact that the resistance increases only 6.6% after 103 tensile bending cycles. The I‐PSCs incorporating the TAI‐TE show record power conversion efficiency (8.34%), maintained at 96% even after 400 bending cycles. TiO2/Ag/indium tin oxide (ITO)‐based transparent electrodes (TEs) with sheet resistance of 6.2 Ω sq−1 and average optical transmittance in the visible of 87.6% are developed. These performances are superior to those of state‐of‐the‐art single‐layer ITO. Polymer solar cells employing such TEs achieve 8.34% efficiency, higher than similar structures on conventional ITO.
      PubDate: 2015-11-05T09:26:04.833806-05:
      DOI: 10.1002/adfm.201503739
  • Improving the Extraction of Photogenerated Electrons with SnO2
           Nanocolloids for Efficient Planar Perovskite Solar Cells
    • Abstract: Great attention to cost‐effective high‐efficiency solar power conversion of trihalide perovskite solar cells (PSCs) has been hovering at high levels in the recent 5 years. Among PSC devices, admittedly, TiO2 is the most widely used electron transport layer (ETL); however, its low mobility which is even less than that of CH3NH3PbI3 makes it not an ideal material. In principle, SnO2 with higher electron mobility can be regarded as a positive alternative. Herein, a SnO2 nanocolloid sol with ≈3 nm in size synthesized at 60 °C was spin‐coated onto the fuorine‐doped tin oxide (FTO) glass as the ETL of planar CH3NH3PbI3 perovskite solar cells. TiCl4 treatment of SnO2‐coated FTO is found to improve crystallization and increase the surface coverage of perovskites, which plays a pivotal role in improving the power conversion efficiency (PCE). In this report, a champion efficiency of 14.69% (Jsc = 21.19 mA cm−2, Voc = 1023 mV, and FF = 0.678) is obtained with a metal mask at one sun illumination (AM 1.5G, 100 mW cm−2). Compared to the typical TiO2, the SnO2 ETL efficiently facilitates the separation and transportation of photogenerated electrons/holes from the perovskite absorber, which results in a significant enhancement of photocurrent and PCE. SnO2 nanocolloids are synthesized for planar CH3NH3PbI3 perovskite solar cells. A champion efficiency of 14.69% is achieved for the SnO2‐based solar cell, which is superior to the TiO2‐based solar cell (13.38%) due to a higher electron mobility and negative conduction band, facilitating the electron injection, charge separation, and collection, which contribute to the improvement of photovoltaic performance.
      PubDate: 2015-11-02T10:28:29.779224-05:
      DOI: 10.1002/adfm.201501264
  • Highly Transparent and Flexible Organic Light‐Emitting Diodes with
           Structure Optimized for Anode/Cathode Multilayer Electrodes
    • Abstract: In this study, a dielectric layer/metal/dielectric layer (multilayer) electrode is proposed as both anode and cathode for use in the fabrication of transparent and flexible organic light‐emitting diodes (TFOLEDs). The structure of multilayer electrodes is optimized by systematic experiments and optical calculations considering the transmittance and efficiency of the device. The details of the multilayer electrode structure are [ZnS (24 nm)/Ag (7 nm)/MoO3 (5 nm)] and [ZnS (3 nm)/Cs2CO3 (1 nm)/Ag (8 nm)/ZnS (22 nm)], as anode and cathode, respectively. The optimized TFOLED design is fabricated on a polyethylene terephthalate (PET) substrate, and the device shows high transmittance (74.22% around 550 nm) although the PET substrate has lower transmittance than glass. The TFOLEDs operate normally under compressive stress; degradation of electrical characteristics is not observed, comparable to conventional OLEDs with ITO and Al as electrodes. In addition, because the fabricated TFOLEDs show a nearly Lambertian emission pattern and a negligible shift of Commission International de l'Eclairage (CIE) coordination, it is concluded that the fabricated TFOLEDs are suitable for use in displays. The highly transparent and flexible organic light‐emitting diodes (TFOLEDs) are fabricated using dielectric layer/metal/dielectric layer (multilayer) electrodes for use as both anodes and cathodes. The structure of multilayer electrodes is optimized to maximize transmittance and to provide flexibility. The fabricated TFOLEDs are highly transparent and show a nearly Lambertian emission pattern without a microcavity effect.
      PubDate: 2015-11-02T10:26:57.394163-05:
      DOI: 10.1002/adfm.201502542
  • Tuning the Microenvironment: Click‐Crosslinked Hyaluronic
           Acid‐Based Hydrogels Provide a Platform for Studying Breast Cancer
           Cell Invasion
    • Authors: Stephanie A. Fisher; Priya N. Anandakumaran, Shawn C. Owen, Molly S. Shoichet
      Abstract: A big challenge in cell culture is the non‐natural environment in which cells are routinely screened, making in vivo phenomena, such as cell invasion, difficult to understand and predict. To study cancer cell invasion, extracellular matrix (ECM) analogs with decoupled mechanical and chemical properties are required. Hyaluronic acid (HA)‐based hydrogels crosslinked with matrix‐metalloproteinase (MMP)‐cleavable peptides are developed to study MDA‐MB‐231 breast cancer cell invasion. Hydrogels are synthesized by reacting furan‐modified HA with bismaleimide peptide crosslinkers in a Diels–Alder click reaction. This new hydrogel takes advantage of the biomimetic properties of HA, which is overexpressed in breast cancer, and eliminates the use of nonadhesive crosslinkers, such as poly(ethylene glycol) (PEG). The crosslink (mechanical) and ligand (chemical) densities are varied independently to evaluate the effects of each parameter on cell migration. Increased crosslink density correlates with decreased MDA‐MB‐231 cell invasion whereas incorporation of MMP‐cleavable sequences within the peptide crosslinker enhances invasion. Increasing the ligand density of pendant GRGDS groups induces cell proliferation, but has no significant impact on invasion. By independently tuning the mechanical and chemical environment of ECM mimetic hydrogels, a platform is provided that recapitulates variable tissue properties and elucidates the role of the microenvironment in cancer cell invasion. A hyaluronic acid‐based hydrogel crosslinked with protease cleavable crosslinks is shown to support breast cancer cell invasion. The crosslink and adhesive ligand densities of the hydrogel are decoupled, allowing the effect of each parameter on cell invasion to be studied. A platform is developed capable of recapitulating a wide range of microenvironments.
      PubDate: 2015-11-02T10:26:50.332461-05:
      DOI: 10.1002/adfm.201502778
  • Organic–Inorganic Perovskite Light‐Emitting Electrochemical
           Cells with a Large Capacitance
    • Authors: Huimin Zhang; Hong Lin, Chunjun Liang, Hong Liu, Jingjing Liang, Yong Zhao, Wenguan Zhang, Mengjie Sun, Weikang Xiao, Han Li, Stefano Polizzi, Dan Li, Fujun Zhang, Zhiqun He, Wallace C. H. Choy
      Abstract: While perovskite light‐emitting diodes typically made with high work function anodes and low work function cathodes have recently gained intense interests. Perovskite light‐emitting devices with two high work function electrodes with interesting features are demonstrated here. Firstly, electroluminescence can be easily obtained from both forward and reverse biases. Secondly, the results of impedance spectroscopy indicate that the ionic conductivity in the iodide perovskite (CH3NH3PbI3) is large with a value of ≈10−8 S cm−1. Thirdly, the shift of the emission spectrum in the mixed halide perovskite (CH3NH3PbI3−xBrx) light‐emitting devices indicates that I− ions are mobile in the perovskites. Fourthly, this work shows that the accumulated ions at the interfaces result in a large capacitance (≈100 μF cm−2). The above results conclusively prove that the organic–inorganic halide perovskites are solid electrolytes with mixed ionic and electronic conductivity and the light‐emitting device is a light‐emitting electrochemical cell. The work also suggests that the organic–inorganic halide perovskites are potential energy‐storage materials, which may be applicable in the field of solid‐state supercapacitors and batteries. Light‐emitting electrochemical cells (LECs) of organic–inorganic perovskite (CH3NH3PbI3) with two high work function electrodes are demonstrated. Results indicate that CH3NH3PbI3 has an ionic conductivity of ≈10−8 S cm−1. The accumulated ions at the interfaces result in a large capacitance, which suggests a potential application in electrochemical energy‐storage devices, such as solid‐state supercapacitors and batteries.
      PubDate: 2015-11-02T10:26:44.453152-05:
      DOI: 10.1002/adfm.201502962
  • Plasmonic Lipid Bilayer Membranes for Enhanced Detection Sensitivity of
           Biolabeling Fluorophores
    • Authors: Rupak Bhattacharya; Chaitanya Indukuri, Nafisa Begam, Oliver H. Seeck, Jaydeep K. Basu
      Abstract: Plasmonics based sensing, using the surface plasmon resonance of metal nanoparticles, has been effectively demonstrated in various applications. Extending this methodology to cell and artificial lipid bilayer membranes is extremely beneficial in enhancing the sensitivity of the detection of binding and cellular transport of molecules across such membranes. Here, the creation of an artificial plasmonic biomembrane template is demonstrated and used to show the enhanced detection sensitivity of certain widely used biomarker molecules. The efficacy of these templates is explained in terms of the ability of the hydrophobic polymer grafted gold nanoparticles used to organize, penetrate, and fluidize the membranes. The enhancement of photoluminescence of the dye molecules used occurs over a reasonably large spectral range as compared to the plasmon resonance of gold nanoparticles. The results could, possibly, be extended to cellular membranes with relevant modifications, as well as to the detection of any other biological molecule appropriately labeled with fluorescent dye molecules, and demonstrate the versatility of these plasmonic bioinspired platforms as potential biochemical sensors. A novel method for ultrasensitive biomarker sensing is achieved by plasmonic bio‐membrane templates for a wide range of fluorophores. Gold nanoparticle assemblies are used on lipid bilayer to get an emission enhancement through Förster resonance energy transfer. Furthermore, the role of nanoparticle membrane binding and penetration as well as its consequence on observed enhanced bio‐fluorophore detection sensitivity is elucidated.
      PubDate: 2015-10-31T02:38:48.034003-05:
      DOI: 10.1002/adfm.201502153
  • Ultrathin Metal Fluoride Interfacial Layers for Use in Organic
           Photovoltaic Cells
    • Authors: Fengyuan Lin; Xingyuan Liu, Yantao Li, Yongsheng Hu, Xiaoyang Guo
      Abstract: A variety of metal fluorides, including lithium fluoride (LiF), magnesium fluoride (MgF2), barium fluoride (BaF2), strontium fluoride (SrF2), aluminum fluoride (AlF3), zirconium fluoride (ZrF4), and cerium fluoride (CeF3), are used as the cathode interfacial layer (CIL) in polymer photovoltaic cells to assess their effect on device performance. CeF3, BaF2, and SrF2 CILs exhibit better performance than a typical LiF CIL. The SrF2‐based device shows a power conversion efficiency (PCE) of 7.17%, which is approximately 9% higher than that of the LiF‐based device; this, to our knowledge, is the first report on the SrF2‐based organic photovoltaic cell device. The open‐circuit voltage (V OC) and fill factor (FF) of the fluoride‐based devices are correlated to the work functions (WFs) of the corresponding metals, which in turn influence the PCE. X‐ray photoelectron spectroscopy measurements of fluoride‐based cathodes reveal the occurrence of a displacement reaction and an interfacial dipole at the fluoride/aluminum interface, which lead to a reduced effective WF of the cathode and improved charge collection. Consequently, an improved PCE is achieved together with an increased V OC and FF. Organic photovoltaic cells with different metal fluorides as the cathode interfacial layers are fabricated. Parameters of the fluoride‐based devices depend on the work function of the corresponding pure metal in the fluoride as a result of the displacement reaction and dipole at the metal fluoride/Al interface.
      PubDate: 2015-10-27T12:30:54.197728-05:
      DOI: 10.1002/adfm.201502871
  • Hybrid Solar Cells: Efficient Perovskite Hybrid Solar Cells via Ionomer
           Interfacial Engineering (Adv. Funct. Mater. 44/2015)
    • Authors: Kai Wang; Chang Liu, Chao Yi, Long Chen, Jiahua Zhu, R. A. Weiss, Xiong Gong
      Pages: 6825 - 6825
      Abstract: On page 6875, R. A. Weiss, X. Gong, and co‐workers re‐engineer the interface between the perovskite active layer and the electron‐extraction layer in perovskite hybrid solar cells, using an ultrathin layer of a highly conductive ionomer. The boosted performance of the resulting solar cells is attributed to the reduction in the charge carrier recombination and leakage current, as well as more efficient charge carrier collection.
      PubDate: 2015-11-23T06:56:42.705164-05:
      DOI: 10.1002/adfm.201570281
  • White Light Phosphors: A Nonrare‐Earth Ions Self‐Activated
           White Emitting Phosphor under Single Excitation (Adv. Funct. Mater.
    • Authors: Hongyu Guo; Junying Zhang, Lun Ma, Jose L. Chavez, Luqiao Yin, Hong Gao, Zilong Tang, Wei Chen
      Pages: 6826 - 6826
      Abstract: J. Zhang, W. Chen, and co‐workers report non‐rare‐earth‐based white light phosphors composed of graphitic nitrogen carbon and copper‐cysteamine on page 6833. These composites exhibit a strong luminescence in the blue and red under ultraviolet single excitation, and are environmentally friendly, easy to synthesize, cost‐effective, and free of rare‐earth elements. These new white light phosphors have a good potential in solid lighting, displays, and crop improvement.
      PubDate: 2015-11-23T06:56:45.68713-05:0
      DOI: 10.1002/adfm.201570282
  • Contents: (Adv. Funct. Mater. 44/2015)
    • Pages: 6827 - 6832
      PubDate: 2015-11-23T06:56:43.124019-05:
      DOI: 10.1002/adfm.201570283
  • A Non‐rare‐Earth Ions Self‐Activated White Emitting
           Phosphor under Single Excitation
    • Authors: Hongyu Guo; Junying Zhang, Lun Ma, Jose L. Chavez, Luqiao Yin, Hong Gao, Zilong Tang, Wei Chen
      Pages: 6833 - 6838
      Abstract: White light phosphors have many potential applications such as solid‐state lighting, full color displays, light source for plant growth, and crop improvement. However, most of these phosphors are rare‐earth‐based materials which are costly and would be facing the challenge of resource issue due to the extremely low abundance of these elements on earth. A new white color composite consisted of a graphitic‐phase nitrogen carbon (g‐C3N4) treated with nitric acid and copper‐cysteamine Cu3Cl(SR)2 is reported herein. Under a single wavelength excitation at 365 nm, these two materials show a strong blue and red luminescence, respectively. It is interesting to find that the white light emission with a quantum yield of 20% can be obtained by mixing these two self‐activated luminescent materials at the weight ratio of 1:1.67. Using a 365 nm near‐ultraviolet chip for excitation, the composite produces a white light‐emitting diode that exhibits an excellent color rendering index of 94.3. These white‐emitting materials are environment friendly, easy to synthesize, and cost‐effective. More importantly, this will potentially eliminate the challenge of rare earth resources. Furthermore, a single chip is used for excitation instead of a multichip, which can greatly reduce the cost of the devices. Composites of g‐C3N4 and Cu3Cl(SR)2 emit white light when they are exited by a single chip at 365 nm. These non‐rare‐earth materials are cheap and easy to approach. They can be applied not only for solid lighting and displays but also for crop improvement.
      PubDate: 2015-10-19T12:57:50.578209-05:
      DOI: 10.1002/adfm.201502641
  • Macroscopic Supramolecular Assembly to Fabricate 3D Ordered Structures:
           Towards Potential Tissue Scaffolds with Targeted Modification
    • Authors: Mengjiao Cheng; Yue Wang, Lingling Yu, Haijia Su, Weidong Han, Zaifu Lin, Jianshu Li, Haojie Hao, Chuan Tong, Xiaolei Li, Feng Shi
      Pages: 6851 - 6857
      Abstract: 3D ordered structures beyond microscale with targeted modification are catching increasing attention due to its application as tissue scaffolds. Especially scaffolds with necessary growth factors at designated locations are meaningful for induced cell differentiation and tissue formation. However, few fabrication methods can address the challenge of introducing bioactive species to the interior targeted places during the preparation process. Herein, for the first time macroscopic supramolecular assembly is applied to obtain such 3D ordered structures and established a proof‐of‐concept idea of complex scaffold with targeted modification. Taking strip‐like polydimethylsilicon building block as a model system, microscaled multilayered structures have been fabricated with parallel aligned building blocks in each layer. The morphology can be adjusted in a flexible way by tuning the number of layer, the space between two adjacent building blocks, and the position and orientation of each PDMS. The as‐prepared 3D structures are demonstrated biocompatible and potential as scaffolds for 3D cell culture. Moreover, bioactive species can be in situ incorporated into designated locations within the 3D structure precisely. In this way, a novel strategy is provided to address the current challenges in fabricating complex 3D tissue scaffolds with localized protein for future induced cell differentiation. For the first time, macroscopic supramolecular assembly is applied to fabricate periodically stacked 3D ordered structures with biocompatibility and potential as tissue scaffolds. Special building blocks with bioactive species are introduced in situ to designated locations within the 3D structure, which provides a proof‐of‐concept idea of fabricating 3D scaffolds with targeted modification of growth factors for directed cell differentiation.
      PubDate: 2015-10-15T04:45:31.29909-05:0
      DOI: 10.1002/adfm.201503366
  • Smart Hybrids of Zn2GeO4 Nanoparticles and Ultrathin g‐C3N4 Layers:
           Synergistic Lithium Storage and Excellent Electrochemical Performance
    • Authors: Xiaodan Li; Yi Feng, Meicheng Li, Wei Li, Hao Wei, Dandan Song
      Pages: 6858 - 6866
      Abstract: Smart hybrids of Zn2GeO4 nanoparticles and ultrathin g‐C3N4 layers (Zn2GeO4/g‐C3N4 hybrids) are realized by a facile solution approach, where g‐C3N4 layers act as an effective substrate for the nucleation and subsequent in situ growth of Zn2GeO4 nanoparticles. A synergistic effect is demonstrated on the two building blocks of Zn2GeO4/g‐C3N4 hybrids for lithium storage: Zn2GeO4 nanoparticles contribute high capacity and serve as spacers to isolate the ultrathin g‐C3N4 layers from restacking, resulting in expanded interlayer and exposed vacancies with doubly bonded nitrogen for extra Li‐ion storage and diffusion pathway; 2D g‐C3N4 layers, in turn, minimize the strain of particles expansion and prevent the formation of unstable solid electrolyte interphase, leading to highly reversible lithium storage. Benefiting from the remarkable synergy, the Zn2GeO4/g‐C3N4 hybrids exhibit highly reversible capacity of 1370 mA h g−1 at 200 mA g−1 after 140 cycles and excellent rate capability of 950 mA h g−1 at 2000 mA g−1. The synergistic effect originating from the hybrids brings out excellent electrochemical performance, and thus casts new light on the development of high‐energy and high‐power anode materials. Smart hybrids of Zn2GeO4 nanoparticles and ultrathin g‐C3N4 layers are prepared, in which Zn2GeO4 nanoparticles are dispersed onto and intercalated into g‐C3N4 layers, thus isolating the ultrathin g‐C3N4 layers from restacking. The structural advantage of Zn2GeO4/g‐C3N4 hybrids conduces to synergistic lithium storage, resulting in highly reversible capacity, fine cycle performance, and excellent rate capability.
      PubDate: 2015-10-13T09:25:04.663538-05:
      DOI: 10.1002/adfm.201502938
  • A Shape Memory Acrylamide/DNA Hydrogel Exhibiting Switchable Dual
    • Pages: 6867 - 6874
      Abstract: Shape memory acrylamide/DNA hydrogels include two different crosslinkers as stabilizing elements. The triggered dissociation of one of the crosslinking elements transforms the shaped hydrogel into an arbitrarily shaped (or shapeless) quasi‐liquid state. The remaining crosslinking element, present in the quasi‐liquid, provides an internal memory that restores the original shaped hydrogel upon the stimulus‐triggered regeneration of the second crosslinking element. Two pH‐sensitive shape memory hydrogels, forming Hoogsten‐type triplex DNA structures, are described. In one system, the shaped hydrogel is stabilized at pH = 7.0 by two different duplex crosslinkers, and the transition of the hydrogel into the shapeless quasi‐liquid proceeds at pH = 5.0 by separating one of the crosslinking units into a protonated cytosine–guanine–cytosine (C–G·C+ ) triplex. The second shaped hydrogel is stabilized at pH = 7.0, by cooperative duplex and thymine–adenine–thymine triplex (T–A·T) bridges. At pH = 10.0, the triplex units separate, leading to the dissociation of the hydrogel into the quasi‐liquid state. The cyclic, pH‐stimulated transitions of the two systems between shaped hydrogels and shapeless states are demonstrated. Integrating the two hydrogels into a shaped “two‐arrowhead” hybrid structure allows the pH‐stimulated cyclic transitions of addressable domains of the hybrid between shaped and quasi‐liquid states. A shape memory acrylamide/DNA hydro­gel exhibiting dual switchable pH‐­responsiveness is presented. The hybrid hydrogel exists at pH = 7.0 in a “two‐arrowhead” structure. One domain is transformed into a quasi‐liquid shapeless state at pH = 5.0, whereas the second domain transforms into the quasi‐liquid state at pH = 10.0. The transformation of the quasi‐liquid to shaped hydrogels is reversible due to internal memory elements.
      PubDate: 2015-10-19T12:57:14.924716-05:
      DOI: 10.1002/adfm.201503134
  • Efficient Perovskite Hybrid Solar Cells via Ionomer Interfacial
    • Authors: Kai Wang; Chang Liu, Chao Yi, Long Chen, Jiahua Zhu, R. A. Weiss, Xiong Gong
      Pages: 6875 - 6884
      Abstract: The surface of the solution‐processed methylammonium lead tri‐iodide (CH3NH3PbI3) perovskite layer in perovskite hybrid solar cells (pero‐HSCs) tends to become rough during operation, which inevitably leads to deterioration of the contact between the perovskite layer and the charge‐extraction layers. Moreover, the low electrical conductivity of the electron extraction layer (EEL) gives rises to low electron collection efficiency and severe charge carrier recombination, resulting in energy loss during the charge‐extraction and ‐transport processes, lowering the efficiency of pero‐HSCs. To circumvent these problems, we utilize a solution‐processed ultrathin layer of a ionomer, 4‐lithium styrenesulfonic acid/styrene copolymer (LiSPS), to re‐engineer the interface of CH3NH3PbI3 in planar heterojunction (PHJ) pero‐HSCs. As a result, PHJ pero‐HSCs are achieved with an increased photocurrent density of 20.90 mA cm−2, an enlarged fill factor of 77.80%, a corresponding enhanced power conversion efficiency of 13.83%, high reproducibility, and low photocurrent hysteresis. Further investigation into the optical and electrical properties and the thin‐film morphologies of CH3NH3PbI3 with and without LiSPS, and the photophysics of the pero‐HSCs with and without LiSPS are shown. These demonstrate that the high performance of the pero‐HSCs incorporated with LiSPS can be attributed to the reduction in both the charge carrier recombination and leakage current, as well as more efficient charge carrier collection, filling of the perforations in CH3NH3PbI3, and a higher electrical conductivity of the LiSPS thin layer. These results demonstrate that our method provides a simple way to boost the efficiency of pero‐HSCs. An ultrathin layer of a highly electrical conductive ionomer, 4‐lithium styrenesulfonic acid/styrene copolymer (LiSPS), is employed to re‐engineer the interface between the perovskite active layer and the electron‐extraction layer in perovskite hybrid solar cells. This results in an enhanced power‐conversion efficiency of 13.83% with high reproducibility and low photocurrent hysteresis.
      PubDate: 2015-10-19T12:56:34.877511-05:
      DOI: 10.1002/adfm.201503160
  • Holey Graphitic Carbon Nitride Nanosheets with Carbon Vacancies for Highly
           Improved Photocatalytic Hydrogen Production
    • Pages: 6885 - 6892
      Abstract: 2D graphitic carbon nitride (GCN) nanosheets have attracted tremendous attention in photocatalysis due to their many intriguing properties. However, the photocatalytic performance of GCN nanosheets is still restricted by the limited active sites and the serious aggregation during the photocatalytic process. Herein, a simple approach to produce holey GCN (HGCN) nanosheets with abundant in‐plane holes by thermally treating bulk GCN (BGCN) under an NH3 atmosphere is reported. These formed in‐plane holes not only endow GCN nanosheets with more exposed active edges and cross‐plane diffusion channels that greatly speed up mass and photogenerated charge transfer, but also provide numerous boundaries and thus decrease the aggregation. Compared to BGCN, the resultant HGCN has a much higher specific surface area of 196 m2 g−1, together with an enlarged bandgap of 2.95 eV. In addition, the HGCN is demonstrated to be self‐modified with carbon vacancies that make HGCN show much broader light absorption extending to the near‐infrared region, a higher donor density, and remarkably longer lifetime of charge carriers. As such, HGCN has a much higher photocatalytic hydrogen production rate of nearly 20 times the rate of BGCN. An efficient etching process, thermal treatment of bulk graphitic carbon nitride under NH3 atmosphere, has been developed to synthesize holey graphitic carbon nitride (HGCN) nanosheets. The resultant HGCN exhibits significantly improved photocatalytic hydrogen production performance under visible light.
      PubDate: 2015-10-15T04:46:07.521533-05:
      DOI: 10.1002/adfm.201503221
  • The Role of Higher Lying Electronic States in Charge Photogeneration in
           Organic Solar Cells
    • Authors: Giulia Grancini; Maddalena Binda, Stefanie Neutzner, Luigino Criante, Vittorio Sala, Alberto Tagliaferri, Guglielmo Lanzani
      Pages: 6893 - 6899
      Abstract: The role of excess photon energy on charge generation efficiency in bulk heterojunction solar cells is still an open issue for the organic photovoltaic community. Here, the spectral dependence of the internal quantum efficiency (IQE) for a poly[2,6‐(4,4‐bis‐(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b;3,4‐b]­dithiophene)‐alt‐4,7‐(2,1,3‐benzothiadiazole)]:6,6‐phenyl‐C61‐butyric acid methyl ester (PCPDTBT:PC60BM)‐based solar cell is derived combining accurate optoelectronic characterization and comprehensive optical modeling. This joint approach is shown to be essential to get reliable values of the IQE. Photons with energy higher than the bandgap of the donor material can effectively contribute to enhance the IQE of the solar cell. This holds true independently of the device architecture, reflecting an intrinsic property of the active material. Moreover, the nanomorphology of the bulk heterojunction plays a crucial role in determining the IQE spectral dependence: the coarser and more crystalline, the lesser the gain in IQE upon high energy excitation. The role of excess photon energy on the charge generation efficiency in PCPDTBT:PC60BM‐based solar cells is unveiled. The spectral shape of the device internal quantum efficiency (IQE) is determined by combining accurate optoelectronic characterization and comprehensive optical modeling. This joint approach is essential to get reliable values of the IQE that shows an increase trend in photon energy. This holds true independently of the device architecture, reflecting an intrinsic property of the active material.
      PubDate: 2015-10-15T04:46:40.31663-05:0
      DOI: 10.1002/adfm.201501873
  • 3D Nanostructured Conjugated Polymers for Optical Applications
    • Authors: Raphael Dehmel; Alexandre Nicolas, Maik R. J. Scherer, Ullrich Steiner
      Pages: 6900 - 6905
      Abstract: The self assembly of block‐copolymers into the gyroid morphology is replicated into 3D nanostructured conjugated polymers. Voided styrenic gyroidal networks are used as scaffolds for the electrodeposition of two poly(3,4‐ethylenedioxythiophene) derivatives and poly(pyrrole). The careful choice of solvents and electrolytes allows the excellent replication of the initial self‐assembled morphology into self‐supporting gyroidal conjugated polymer networks. The nanostructured films are employed to fabricate electrochromic devices, exhibiting excellent color contrast upon switching, with fast switching speeds. The versatility and reliability of this method are demonstrated by the creation of switchable Fresnel zone plates, with which the focussing of light can be switched on and off. Mesoporous networks of conjugated poly­mers were synthesized by electropoly­merisation into templates created by block‐copolymer self‐assembly. The nanostructured conductive polymer layers were employed to manufacture electrochromic zone‐plates that reversibly switch on and off the focussing of light.
      PubDate: 2015-10-19T12:58:02.184129-05:
      DOI: 10.1002/adfm.201502392
  • 3D Porous N‐Doped Graphene Frameworks Made of Interconnected
           Nanocages for Ultrahigh‐Rate and Long‐Life Li–O2
    • Authors: Changtai Zhao; Chang Yu, Shaohong Liu, Juan Yang, Xiaoming Fan, Huawei Huang, Jieshan Qiu
      Pages: 6913 - 6920
      Abstract: The inferior rate capability and poor cycle stability of the present Li–O2 batteries are still critical obstacles for practice applications. Configuring novel and integrated air electrode materials with unique structure and tunable chemical compositions is one of the efficient strategies to solve these bottleneck problems. Herein, a novel strategy for synthesis of 3D porous N‐doped graphene aerogels (NPGAs) with frameworks constructed by interconnected nanocages with the aid of polystyrene sphere@polydopamine is reported. The interconnected nanocages as the basic building unit of graphene sheets are assembled inside the skeletons of 3D graphene aerogels, leading to the 3D NPGA with well‐developed interconnected channels and the full exposure of electrochemically active sites. Benefiting from such an unique structure, the as‐made NPGA delivers a high specific capacity, an excellent rate capacity of 5978 mA h g−1 at 3.2 A g−1, and long cycle stability, especially at a large current density (54 cycles at 1 A g−1), indicative of boosted rate capability and cycle life as air electrodes for Li–O2 batteries. More importantly, based on the total mass of C+Li2O2, a gravimetric energy density of 2400 W h kg−1 for the NPGA–O2//Li cell is delivered at a power density of 1300 W kg−1. 3D porous N‐doped graphene frameworks constructed by interconnected ­nanocages are configured with the aid of polystyrene sphere@polydopamine. The interconnected nanocages as the ­basic building unit of graphene sheets are ­assembled inside skeletons of graphene aerogels, resulting in well‐developed ­interconnected channels and full exposure of heteroatom sites, thus help to boost the rate capability and cycle life for Li–O2 batteries.
      PubDate: 2015-10-19T12:57:29.505565-05:
      DOI: 10.1002/adfm.201503077
  • Direct Transfer Printing with Metal Oxide Layers for Fabricating Flexible
           Nanowire Devices
    • Pages: 6921 - 6926
      Abstract: A direct printing method for fabricating devices by using metal oxide transfer layers instead of conventional transfer media such as polydimethylsiloxane is presented. Metal oxides are not damaged by organic solvents; therefore, electrodes with gaps less than 2 μm can be defined on a metal oxide transfer layer through photolithography. In order to determine a suitable metal oxide for use as transfer layer, the surface energies of various metal oxides are measured, and Au layers deposited on these oxides are transferred onto polyvinylphenol (PVP). To verify the feasibility of our approach, Au source–drain electrodes on transfer layers and Si nanowires (NWs) addressed by the dielectrophoretic (DEP) alignment process are transferred onto rigid and flexible PVP‐coated substrates. Based on transfer test and DEP process, Al2O3 is determined to be the best transfer layer. Finally, Si NWs field effect transistors (FETs) are fabricated on a rigid Si substrate and a flexible polyimide film. As the channel length decreases from 3.442 to 1.767 μm, the mobility of FET on the Si substrate increases from 127.61 ± 37.64 to 181.60 ± 23.73 cm2 V−1 s−1. Furthermore, the flexible Si NWs FETs fabricated through this process show enhanced electrical properties with an increasing number of bending cycles. Flexible Si nanowire field effect transistors (FETs) are fabricated by a direct printing method applying an Al2O3 layer. As metal oxide is not damaged by organic solvents, source–drain electrodes with less than 2 μm can be patterned by photolithography. Unlike typical flexible devices, the FETs produced through the proposed process exhibit enhanced electrical properties with an increasing number of bending cycles.
      PubDate: 2015-10-15T00:42:14.351719-05:
      DOI: 10.1002/adfm.201503502
  • Robust Prediction of Personalized Cell Recognition from a Cancer
           Population by a Dual Targeting Nanoparticle Library
    • Authors: Tu C. Le; Bing Yan, David A. Winkler
      Pages: 6927 - 6935
      Abstract: Nanomaterials are used increasingly in diagnostics and therapeutics, particularly for malignancies. Efficient targeting of nanoparticles to specific cells is an important requirement for the development of successful nanoparticle‐based theranostics and personalized medicines. Gold nanoparticles are surface modified using a library of small organic molecules, and optionally folate, to investigate their ability to target four cell lines from common cancers, three having high levels of folate receptors expression. Uptake of these nanoparticles varies widely with surface chemistriy and cell lines. Sparse machine learning methods are used to computationally model surface chemistry–uptake relationships, to make quantitative predictions of uptake for new nanoparticle surface chemistries, and to elucidate molecular aspects of the interactions. The combination of combinatorial surface chemistry modification and machine learning models will facilitate the rapid development of targeted theranostics. Efficient targeting of nanoparticles to specific cells is an important requirement for the development of successful nanoparticle‐based cancer theranostics and personalized medicines. The cancer cell targeting ability of gold nanoparticles coated with a library of small organic molecules plus folate is modeled. Computational models can predict the degree of uptake of the nanoparticles as a function of surface chemistry.
      PubDate: 2015-10-20T10:36:40.339979-05:
      DOI: 10.1002/adfm.201502811
  • Working Principles of Perovskite Photodetectors: Analyzing the Interplay
           Between Photoconductivity and Voltage‐Driven Energy‐Level
    • Pages: 6936 - 6947
      Abstract: Organic–inorganic lead halide perovskites have recently received significant attention as active materials for high‐performance photovoltaics and photodetectors. However, the understanding of their operation mechanism remains limited. High‐gain, low‐voltage CH3NH3PbI3 photodetectors in various architectures are demonstrated herein. Photomultiplication in all structures with direct contact of fluorine‐doped tin oxide (FTO) and perovskite with the highest responsivity 208 A W−1 corresponding to an incident photon‐to‐current efficiency of 47 000% is observed. Studying the dynamics and temperature dependence, a slow process with an activation energy of 420 ± 90 meV in the time scale of seconds is found, which is essential to photocurrent multiplication. A model based on ion migration to explain the observed transients and the photomultiplication is developed. The accumulation of negative ionic charge at the FTO/perovskite interface under reverse bias lowers the FTO work function allowing for direct hole injection into the perovskite valence band. Under illumination, the conductivity of perovskite is increased and the device behaves similar to a photoconductor. Different organic–inorganic lead halide perovskites‐based photodetector architectures showing incident photon‐to‐current efficiency of up to 47 000% at low operation voltage are investigated. The general working principle is explained in terms of a voltage‐driven work function alignment of fluorine‐doped tin oxide (FTO) with the perovskite due to the accumulation of negative ionic charge at their interface.
      PubDate: 2015-10-20T10:36:05.585613-05:
      DOI: 10.1002/adfm.201503188
  • Alginate Hydrogel Microencapsulation Inhibits Devitrification and Enables
           Large‐Volume Low‐CPA Cell Vitrification
    • Authors: Haishui Huang; Jung Kyu Choi, Wei Rao, Shuting Zhao, Pranay Agarwal, Gang Zhao, Xiaoming He
      Pages: 6939 - 6850
      Abstract: Cryopreservation of stem cells is important to meet their ever‐increasing demand by the burgeoning cell‐based medicine. The conventional slow freezing for stem cell cryopreservation suffers from inevitable cell injury associated with ice formation and the vitrification (i.e., no visible ice formation) approach is emerging as a new strategy for cell cryopreservation. A major challenge to cell vitrification is intracellular ice formation (IIF, a lethal event to cells) induced by devitrification (i.e., formation of visible ice in previously vitrified solution) during warming the vitrified cells at cryogenic temperature back to super‐zero temperatures. Consequently, high and toxic concentrations of penetrating cryoprotectants (i.e., high CPAs, up to ≈8 m) and/or limited sample volumes (up to ≈2.5 μL) have been used to minimize IIF during vitrification. It is revealed that alginate hydrogel microencapsulation can effectively inhibit devitrification during warming. The data show that if ice formation were minimized during cooling, IIF is negligible in alginate hydrogel microencapsulated cells during the entire cooling and warming procedure of vitrification. This enables vitrification of pluripotent and multipotent stem cells with up to ≈4 times lower concentration of penetrating CPAs (up to 2 m, low CPA) in up to ≈100 times larger sample volume (up to ≈250 μL, large volume). Alginate hydrogel microcapsules are exceptional in inhibiting devitrification in cryopreserved samples during warming, which enables cryopreservation by vitrification in ≈100 times larger volume using a low and nontoxic concentration of cryoprotectants (i.e., low CPAs) and makes it possible to practically use the low‐CPA vitrification technology for cryopreserving stem cells.
      PubDate: 2015-10-15T04:46:28.074771-05:
      DOI: 10.1002/adfm.201503047
  • Hydrogen Evolution: Holey Graphitic Carbon Nitride Nanosheets with Carbon
           Vacancies for Highly Improved Photocatalytic Hydrogen Production (Adv.
           Funct. Mater. 44/2015)
    • Pages: 6952 - 6952
      Abstract: On page 6885, Z‐H. Huang, Q.‐H.Yang, and co‐workers demonstrate an efficient thermal etching process for the synthesis of holey graphitic carbon nanosheets, via etching of bulk graphitic carbon nitride under an ammonia atmosphere. These nanosheets exhibit significantly improved photocatalytic activity towards hydrogen evolution reactions under visible light conditions, up to 20 times that of the bulk material.
      PubDate: 2015-11-23T06:56:46.800684-05:
      DOI: 10.1002/adfm.201570285
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327
About JournalTOCs
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-2015