for Journals by Title or ISSN
for Articles by Keywords
help
  Subjects -> CHEMISTRY (Total: 837 journals)
    - ANALYTICAL CHEMISTRY (48 journals)
    - CHEMISTRY (586 journals)
    - CRYSTALLOGRAPHY (22 journals)
    - ELECTROCHEMISTRY (26 journals)
    - INORGANIC CHEMISTRY (41 journals)
    - ORGANIC CHEMISTRY (46 journals)
    - PHYSICAL CHEMISTRY (68 journals)

CHEMISTRY (586 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: 31)
ACS Catalysis     Full-text available via subscription   (Followers: 27)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 16)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 9)
ACS Macro Letters     Full-text available via subscription   (Followers: 20)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 24)
ACS Nano     Full-text available via subscription   (Followers: 199)
ACS Photonics     Full-text available via subscription   (Followers: 6)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 11)
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: 6)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 5)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 5)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 11)
Advanced Functional Materials     Hybrid Journal   (Followers: 41)
Advanced Science Focus     Free   (Followers: 1)
Advances in Chemical Engineering and Science     Open Access   (Followers: 23)
Advances in Chemical Science     Open Access   (Followers: 9)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 15)
Advances in Drug Research     Full-text available via subscription   (Followers: 17)
Advances in Enzyme Research     Open Access  
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: 11)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 9)
Advances in Polymer Science     Hybrid Journal   (Followers: 37)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 10)
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: 29)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 86)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 11)
American Journal of Chemistry     Open Access   (Followers: 19)
American Journal of Plant Physiology     Open Access   (Followers: 10)
American Mineralogist     Full-text available via subscription   (Followers: 7)
Analyst     Full-text available via subscription   (Followers: 37)
Angewandte Chemie     Hybrid Journal   (Followers: 20)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 134)
Annales UMCS, Chemia     Open Access   (Followers: 2)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access  
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 1)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 2)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 6)
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: 12)
Anti-Infective Agents     Hybrid Journal   (Followers: 1)
Antiviral Chemistry and Chemotherapy     Full-text available via subscription  
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 4)
Applied Spectroscopy     Full-text available via subscription   (Followers: 15)
Applied Surface Science     Hybrid Journal   (Followers: 23)
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: 4)
Autophagy     Full-text available via subscription   (Followers: 2)
Avances en Quimica     Open Access   (Followers: 1)
Biochemical Pharmacology     Hybrid Journal   (Followers: 6)
Biochemistry     Full-text available via subscription   (Followers: 153)
Biochemistry Insights     Open Access   (Followers: 4)
Biochemistry Research International     Open Access   (Followers: 4)
BioChip Journal     Hybrid Journal   (Followers: 1)
Bioinorganic Chemistry and Applications     Open Access   (Followers: 4)
Bioinspired Materials     Open Access  
Biointerface Research in Applied Chemistry     Open Access   (Followers: 1)
Biointerphases     Open Access  
Biomacromolecules     Full-text available via subscription   (Followers: 18)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 6)
Biomedical Chromatography     Hybrid Journal   (Followers: 7)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 2)
BioNanoScience     Partially Free   (Followers: 4)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 29)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 23)
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: 2)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 14)
C - Journal of Carbon Research     Open Access  
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 3)
Canadian Journal of Chemistry     Full-text available via subscription   (Followers: 6)
Canadian Mineralogist     Full-text available via subscription   (Followers: 1)
Carbohydrate Research     Hybrid Journal   (Followers: 11)
Carbon     Hybrid Journal   (Followers: 70)
Catalysis for Sustainable Energy     Open Access   (Followers: 3)

        1 2 3 4 5 6 | Last

Journal Cover   Advanced Functional Materials
  [SJR: 4.682]   [H-I: 156]   [41 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  [1609 journals]
  • Magnetite Nanostructured Porous Hollow Helical Microswimmers for Targeted
           Delivery
    • Authors: Xiaohui Yan; Qi Zhou, Jiangfan Yu, Tiantian Xu, Yan Deng, Tao Tang, Qian Feng, Liming Bian, Yan Zhang, Antoine Ferreira, Li Zhang
      Abstract: Bacteria‐inspired magnetic helical micro‐/nanoswimmers can be actuated and steered in a fuel‐free manner using a low‐strength rotating magnetic field, generating remotely controlled 3D locomotion with high precision in a variety of biofluidic environments. They are therefore envisioned for biomedical applications related to targeted diagnosis and therapy. In this article, a porous hollow microswimmer possessing an outer shell aggregated by mesoporous spindle‐like magnetite nanoparticles (NPs) and a helical‐shaped inner cavity is proposed. The fabrication is straightforward via a cost‐effective mass‐production process of biotemplated synthesis using helical microorganisms. Here, Spirulina‐based fabrication is demonstrated as an example. The fabricated microswimmers are superparamagnetic and exhibit low cytotoxicity. They are also capable of performing structural disassembly to form individual NPs using ultrasound when needed. For the first time in the literature of helical microswimmers, a porous hollow architecture is successfully constructed, achieving an ultrahigh specific surface area for surface functionalization and enabling diffusion‐based cargo loading/release. Furthermore, experimental and analytical results indicate better swimming performance of the microswimmers than the existing non‐hollow helical micromachines of comparable sizes and dimensions. These characteristics of the as‐proposed microswimmers suggest a novel microrobotic tool with high loading capacity for targeted delivery of therapeutic/imaging agents in vitro and in vivo. Porous hollow helical microswimmers composed of spindle‐like magnetite nanoparticles are developed using a new method of fabrication based on biotemplated synthesis. Due to the unique micro‐/nanostructures, the as‐fabricated microswimmers are characterized with multiple properties desired by targeted diagnosis and therapy, thus suggesting a novel microrobotic tool for potential biomedical applications.
      PubDate: 2015-07-24T06:59:48.726027-05:
      DOI: 10.1002/adfm.201502248
       
  • A Hybrid Silica Nanoreactor Framework for Encapsulation of Hollow
           Manganese Oxide Nanoparticles of Superior T1 Magnetic Resonance Relaxivity
           
    • Authors: Benedict You Wei Hsu; Michael Ng, Yu Zhang, Siew Yee Wong, Kishore Bhakoo, Xu Li, John Wang
      Abstract: A new hybrid nanoreactor framework with poly(ethylene oxide)‐perforated silica walls is designed to encapsulate hollow manganese oxide nanoparticles (MONs) of high distinctness and homogeneity. Achieved by an interfacial templating scheme, the nanoreactor ensures that acidic etching of MONs by an acetate buffer solution is highly controlled for precise control of the hollow interior. As such, hollow MONs with different nanostructures are developed successfully through a facile acetate buffer solution etching. The resultant hollow MONs are integrated within the hybrid nanoreactor and demonstrate superior r1 relativity of up to 2.58 mm−1 s−1 for T1 magnetic resonance imaging (MRI). By modifying the nanoreactor architecture, it is also demonstrated that the efficacy of MONs as T1 MRI contrast agents can be significantly improved if an optimal cluster of hollow MONs is encapsulated into the hybrid silica framework. The evolution of core morphology with time is studied to elucidate the etching mechanism. It is revealed that the hollow formation arises due to the surface stabilization of MONs by acetate ions and the subsequent acidic etching of the interior core in a sporadic manner. This is different from the commonly reported nanoscale Kirkendall effect or the selective etching of the core–shell MnO/Mn3O4 structure. A hybrid silica nanoreactor is designed for preparing hollow manganese oxide nanoparticles (MONs) under highly controlled conditions. Well‐defined hollow MONs exhibit high r1 relativity of up to 2.58 mm−1 s−1 when multiple MONs are encapsulated within the framework. The formation of hollow MONs is due to surface stabilization by acetate ions, followed by acidic etching of the core in a sporadic manner.
      PubDate: 2015-07-24T06:57:15.794249-05:
      DOI: 10.1002/adfm.201501269
       
  • Painting and Direct Writing of Silver Nanostructures on Phosphate Glass
           with Electron Beam Irradiation
    • Authors: Kyle E. Jacobs; Placid M. Ferreira
      Abstract: Surfaces with silver nanostructures are useful, due to their potential to resonate strongly with visible light. This report demonstrates a process for the directed extraction of silver at the surface of a transparent superionic conductor. A focused electron beam incident on superionic AgIAgPO3 glass results in localized negative charge deposition, which is neutralized by the electrochemical reduction of free silver ions. This process was characterized for beam energies ranging from 1 to 12 kV and primary beam fluence ranging from 50 pC μm−2 to 35 nC μm−2. For electron fluence less than 2.5 nC μm−2 the process produces vibrant coloration of the glass which can be tuned throughout the entire visible spectrum. Fluence greater than 2.5 nC μm−2 results in the controlled writing of bulk silver on the surface, with a minimum line width as small as 400 nm and narrow gaps as small as 50 nm. The high ionic conductivity of the substrate is shown to be a vital component to the process, allowing the wide range of colors to be produced along with the controlled, nondendritic growth of silver structures. Direct writing of silver nanoparticles in a solid‐state superionic conductor is performed using an electron beam. Smaller nanoparticles produced at low beam fluence interact plasmonically to produce vivid coloration to the otherwise transparent substrate. Increased beam fluence results in the extraction of bulk‐like silver particles in the shape of the beam‐irradiated region.
      PubDate: 2015-07-24T06:57:08.574725-05:
      DOI: 10.1002/adfm.201501965
       
  • Temperature Dependence of the Piezophototronic Effect in CdS Nanowires
    • Authors: Ruomeng Yu; Xingfu Wang, Wenzhuo Wu, Caofeng Pan, Yoshio Bando, Naoki Fukata, Youfan Hu, Wenbo Peng, Yong Ding, Zhong Lin Wang
      Abstract: The piezophototronic effect is known as a three‐way coupling between piezoelectric polarization, semiconductor property, and optical excitation in piezoelectric semiconductor materials to modify their energy band structures by strain‐induced piezoelectric polarization charges, and thus to tune/control their optoelectronic processes of charge carrier generation, separation, recombination, and transport. In this work, the temperature dependence of the piezophototronic effect in wurtzite‐structured CdS nanowires is investigated from 77 to 300 K. The piezophototronic effect is enhanced by over 550% under lower temperature due to the increased effective piezoelectric polarization surface/interface charges resulting from the reduced screening effect by decreased mobile charge carriers in CdS nanowires. Optoelectronic performances of CdS nanowires are systematically investigated under various light illuminations, strains, and temperatures. By analyzing the corresponding band diagrams, the piezophototronic effect is found to dominate the transport and separation processes of charge carriers. This study presents in‐depth fundamental understanding about the piezophototronic effect and provides guidance for its future applications in optoelectronic devices. The piezophototronic effect is the use of piezoelectric polarization charges for tuning/controlling charge carrier generation, separation, recombination, and transport process. The piezophototronic effect is enhanced by over 550% under lower temperature due to the increased effective piezoelectric polarization surface/interface charges resulted from the reduced screening effect by decreased mobile charge carriers in CdS nanowires.
      PubDate: 2015-07-24T06:57:00.098531-05:
      DOI: 10.1002/adfm.201501986
       
  • Influence of Molecular Geometry of Perylene Diimide Dimers and Polymers on
           Bulk Heterojunction Morphology Toward High‐Performance Nonfullerene
           Polymer Solar Cells
    • Authors: Chen‐Hao Wu; Chu‐Chen Chueh, Yu‐Yin Xi, Hong‐Liang Zhong, Guang‐Peng Gao, Zhao‐Hui Wang, Lilo D. Pozzo, Ten‐Chin Wen, Alex K.‐Y. Jen
      Abstract: In this study, we investigate the influence of molecular geometry of the donor polymers and the perylene diimide dimers (di‐PDIs) on the bulk heterojunction (BHJ) morphology in the nonfullerene polymer solar cells (PSCs). The results reveal that the pseudo 2D conjugated poly[4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b;4,5‐b′]dithiophene‐2,6‐diyl‐alt‐(4‐(2‐ethylhexyl)‐3‐fluorothieno[3,4‐b]thiophene‐)‐2‐carboxylate‐2‐6‐diyl)] (PTB7‐Th) has better miscibility with both bay‐linked di‐PDI (B‐di‐PDI) and hydrazine‐linked di‐PDI (H‐di‐PDI) compared to its 1D analog, poly[[4,8‐bis[(2‐ethylhexyl)oxy]benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl][3‐fluoro‐2‐[(2‐ethylhexyl)carbonyl]thieno[3,4‐b]thiophenediyl]] (PTB7), to facilitate more efficient exciton dissociation in the BHJ films. However, the face‐on oriented π–π stacking of PTB7‐Th is severely disrupted by the B‐di‐PDI due to its more flexible structure. On the contrary, the face‐on oriented π–π stacking is only slightly disrupted by the H‐di‐PDI, which has a more rigid structure to provide suitable percolation pathways for charge transport. As a result, a very high power conversion efficiency (PCE) of 6.41% is achieved in the PTB7‐Th:H‐di‐PDI derived device. This study shows that it is critical to pair suitable polymer donor and di‐PDI‐based acceptor to obtain proper BHJ morphology for achieving high PCE in the nonfullerene PSCs. Suitable selection of perylene diimide dimer (di‐PDI)‐based acceptors and polymer donors is essential to optimize the bulk heterojunction morphology. When blended with the 2D polymer, PTB7‐Th, the rigidly hydrazine‐linked di‐PDI affords the recorded power conversion efficiency of 6.4% due to excellent miscibility for efficient exciton dissociation and appropriate percolation pathways for charge transport.
      PubDate: 2015-07-24T06:56:51.512825-05:
      DOI: 10.1002/adfm.201501971
       
  • Functional Mesoporous Carbon‐Coated Separator for Long‐Life,
           High‐Energy Lithium–Sulfur Batteries
    • Authors: Juan Balach; Tony Jaumann, Markus Klose, Steffen Oswald, Jürgen Eckert, Lars Giebeler
      Abstract: The lithium–sulfur (Li–S) battery is regarded as the most promising rechargeable energy storage technology for the increasing applications of clean energy transportation systems due to its remarkable high theoretical energy density of 2.6 kWh kg−1, considerably outperforming today's lithium‐ion batteries. Additionally, the use of sulfur as active cathode material has the advantages of being inexpensive, environmentally benign, and naturally abundant. However, the insulating nature of sulfur, the fast capacity fading, and the short lifespan of Li–S batteries have been hampered their commercialization. In this paper, a functional mesoporous carbon‐coated separator is presented for improving the overall performance of Li–S batteries. A straightforward coating modification of the commercial polypropylene separator allows the integration of a conductive mesoporous carbon layer which offers a physical place to localize dissolved polysulfide intermediates and retain them as active material within the cathode side. Despite the use of a simple sulfur–carbon black mixture as cathode, the Li–S cell with a mesoporous carbon‐coated separator offers outstanding performance with an initial capacity of 1378 mAh g−1 at 0.2 C, and high reversible capacity of 723 mAh g−1, and degradation rate of only 0.081% per cycle, after 500 cycles at 0.5 C. A functional mesoporous carbon‐coated separator is developed for lithium–sulfur batteries, which exhibit significant enhancements in their performance: high capacities, long cycle life, and low capacity fading at different current rates. These improvements highlight the importance of the rational design of modified separators with mesoporous carbon structures and this proof of concept will bring reliability for advanced high‐performance lithium–sulfur batteries.
      PubDate: 2015-07-24T06:55:54.285737-05:
      DOI: 10.1002/adfm.201502251
       
  • Masthead: (Adv. Funct. Mater. 28/2015)
    • PubDate: 2015-07-21T06:19:19.315165-05:
      DOI: 10.1002/adfm.201570192
       
  • Enhancement in Organic Photovoltaic Efficiency through the Synergistic
           Interplay of Molecular Donor Hydrogen Bonding and π‐Stacking
    • Authors: Nathan T. Shewmon; Davita L. Watkins, Johan F. Galindo, Raghida Bou Zerdan, Jihua Chen, Jong Keum, Adrian E. Roitberg, Jiangeng Xue, Ronald K. Castellano
      Abstract: For organic photovoltaic (OPV) cells based on the bulk heterojunction (BHJ) structure, it remains challenging to rationally control the degree of phase separation and percolation within blends of donors and acceptors to secure optimal charge separation and transport. Reported is a bottom‐up, supramolecular approach to BHJ OPVs wherein tailored hydrogen bonding (H‐bonding) interactions between π‐conjugated electron donor molecules encourage formation of vertically aligned donor π‐stacks while simultaneously suppressing lateral aggregation; the programmed arrangement facilitates fine mixing with fullerene acceptors and efficient charge transport. The approach is illustrated using conventional linear or branched quaterthiophene donor chromophores outfitted with terminal functional groups that are either capable or incapable of self‐complementary H‐bonding. When applied to OPVs, the H‐bond capable donors yield a twofold enhancement in power conversion efficiency relative to the comparator systems, with a maximum external quantum efficiency of 64%. H‐bond promoted assembly results in redshifted absorption (in neat films and donor:C60 blends) and enhanced charge collection efficiency despite disparate donor chromophore structure. Both features positively impact photocurrent and fill factor in OPV devices. Film structural characterization by atomic force microscopy, transmission electron microscopy, and grazing incidence wide angle X‐ray scattering reveals a synergistic interplay of lateral H‐bonding interactions and vertical π‐stacking for directing the favorable morphology of the BHJ. Tailored hydrogen‐bonding interactions between molecular donors in blends with C60 result in vertically aligned π‐stacks, shorter π‐stacking distances, higher charge collection efficiency, and redshifted absorption relative to non‐H‐bonding comparator molecules. For two quaterthiophene families, the benefits result in a twofold enhancement in power conversion efficiency and a maximum external quantum efficiency of 64% in photovoltaic devices.
      PubDate: 2015-07-20T05:08:59.72704-05:0
      DOI: 10.1002/adfm.201501815
       
  • Virus‐Inspired Mimics Based on Dendritic Lipopeptides for Efficient
           Tumor‐Specific Infection and Systemic Drug Delivery
    • Authors: Zhijun Zhang; Xiao Zhang, Xianghui Xu, Yunkun Li, Yachao Li, Dan Zhong, Yiyan He, Zhongwei Gu
      Abstract: Herein, multifunctional mimics of viral architectures and infections self‐assembled from tailor‐made dendritic lipopeptides for programmed targeted drug delivery are reported. These viral mimics not only have virus‐like components and nanostructures, but also possess virus‐like infections to solid tumor and tumor cells. Encouragingly, the viral mimics provide the following distinguished features for tumor‐specific systemic delivery: i) stealthy surface to resist protein interactions and prolong circulation time in blood, ii) well‐defined nanostructure for passive targeting to solid tumor site, iii) charge‐tunable shielding for tumor extracellular pH targeting, iv) receptor‐mediated targeting to enhance tumor‐specific uptake, and v) supramolecular lysine‐rich architectures mimicking viral subcellular targeting for efficient endosomal escape and nuclear delivery. This bioinspired design make in vivo tumor suppression by drug‐loaded viral mimics against BALB/c mice bearing 4T1 tumor greatly exceed the positive control group (more than three times). More importantly, viral mimics hold great potentials to reduce side effects and decrease tumor metastasis after systemic administration. Dendritic lipopeptide–based mimics of viral architectures and infections can serve as versatile nanoplatform for tumor‐specific targeting delivery. Virus‐inspired mimics largely enhance in vitro and in vivo tumor suppression of antitumor drugs, as well as hold great potentials to reduce side effects and decrease tumor metastasis after systemic administration.
      PubDate: 2015-07-16T06:06:27.498558-05:
      DOI: 10.1002/adfm.201502049
       
  • A New Salt‐Baked Approach for Confining Selenium in Metal
           Complex‐Derived Porous Carbon with Superior Lithium Storage
           Properties
    • Authors: Xiaona Li; Jianwen Liang, Zhiguo Hou, Wanqun Zhang, Yan Wang, Yongchun Zhu, Yitai Qian
      Abstract: For lithium‐selenium batteries, commercial applications are hindered by the inferior electrical conductivity of selenium and the low utilization ratio of the active selenium. Here, we report a new baked‐in‐salt approach to enable Se to better infiltrate into metal‐complex‐derived porous carbon (Se/MnMC‐B). The approach uses the confined, narrow space that is sandwiched between two compact NaCl solid disks, thus avoiding the need for protection with argon or a vacuum environment during processing. The electrochemical properties for both lithium and sodium storage of our Se/MnMC‐B cathode were found to be outstanding. For lithium storage, the Se/MnMC‐B cathode (with 72% selenium loading) exhibited a capacity of 580 mA h g−1 after 1000 cycles at 1 C, and an excellent rate capability was achieved at 20 C and 510 mA h g−1. For sodium storage, a specific capacity of 535 mA h g−1 was achieved at 0.1 C after 150 cycles. These results demonstrate the potential of this approach as a new effective general synthesis method for confining other low melting point materials into a porous carbon matrix. A new baked‐in‐salt approach to let Se infiltrate into porous carbon is proposed, without the need for a protective argon or vacuum environment. The use of NaCl, which has a higher specific heat capacity than Se, assures an almost constant fabrication temperature, by reducing temperature fluctuations in the system. The Se/C sample exhibits excellent electrochemical performance both in Li–Se and Na–Se batteries. Furthermore, this approach should also be effective for confining other low melting point materials into porous carbon.
      PubDate: 2015-07-16T06:06:12.347197-05:
      DOI: 10.1002/adfm.201501956
       
  • Ultrafine Amorphous SnOx Embedded in Carbon Nanofiber/Carbon Nanotube
           Composites for Li‐Ion and Na‐Ion Batteries
    • Authors: Biao Zhang; Jiaqiang Huang, Jang‐Kyo Kim
      Abstract: Core–shell‐structured, ultrafine SnOx/carbon nanofiber (CNF)/carbon nanotube composite films are in situ synthesized by electrospinning through a dual nozzle. The carbon shell layer functions as a buffer to prevent the separation of SnOx particles from the CNF core, allowing full utilization of high‐capacity SnOx in both Li‐ion and Na‐ion batteries. The composite electrodes reveal an anomalous Li‐ and Na‐ion storage mechanism where all the intermediate phases, like LixSn and NaxSn alloys, maintain amorphous states during the entire charge/discharge process. The uniform dispersion on an atomic scale and the amorphous state of the SnOx particles remain intact in the carbon matrix without growth or crystallization even after 300 cycles, which is responsible for sustaining excellent capacity retention of the electrodes. These discoveries not only shed new insights into fundamental understanding of the electrochemical behavior of SnOx electrodes but also offer a potential strategy to improve the cyclic stability of other types of alloy anodes that suffer from rapid capacity decays due to large volume changes. Li‐ion and Na‐ion storage behaviors of ultrafine amorphous SnOx particles embedded in carbon nanofiber/carbon nanotube composites are investigated. They reveal an anomalous electrochemical mechanism with all intermediate phases maintaining an amorphous state during the entire charge/discharge process, which gives rise to excellent reversibility of the electrodes.
      PubDate: 2015-07-14T14:00:44.80087-05:0
      DOI: 10.1002/adfm.201501498
       
  • Catalase Nanocapsules Protected by Polymer Shells for Scavenging Free
           Radicals of Tobacco Smoke
    • Authors: Lizhi Liu; Wei Yu, Dan Luo, Zhenjie Xue, Xiaoyun Qin, Xiaohua Sun, Jincai Zhao, Jianlong Wang, Tie Wang
      Abstract: Free radicals in tobacco smoke trigger numerous lung diseases, which are worldwide health considerations. The ideal free‐radical, tobacco‐smoke scavenger must be highly reactive and temperature resistant. Catalases (CATs) show attractive potential to scavenge free radicals in tobacco smoke, because of their higher reaction rate compared to that of non‐catalyzed reactions. Their fragile nature, however, diminishes their catalytic activity in hot tobacco smoke. Therefore, it is essential to enhance the structural integrity and catalytic stability of these enzymes under severe environmental conditions. In order to improve the thermal stability of CATs, we have developed a facile approach to produce CAT nanocapsules (nCATs) by encapsulating a single enzyme in a polyacrylamide (PAAM) shell. The rigid polymer shells on the CATs surface prevents their free deformation. The secondary structure of the enzyme is retained and their dissociation is almost nil even under high operational temperatures. As a result, the structural stability and thermal resistance of the enzyme are significantly enhanced. The nCATs are covalently bound on cellulose acetate fibers to enable the enzyme sticking to the cigarette filters.The electron paramagnetic resonance (EPR) and Saltzman procedure reveal that the nCATs are able to efficiently scavenge 90% of the free radicals in tobacco smoke. The use of such nCATs with improved enzyme thermal stability opens up new opportunities for future application in cigarette filters. The catalytic activity of catalases can be retained by encapsulating the enzymes in rigid polymer shells. The covalent bonding with the polymer shells protects the catalases from dissociating into subunits under high operational temperature. As‐prepared catalase nanocapsules can be incorporated in cigarette filters as scavengers to clean free radicals from tobacco smoke.
      PubDate: 2015-07-14T14:00:15.664063-05:
      DOI: 10.1002/adfm.201501850
       
  • Wireless Microfluidic Systems for Programmed, Functional Transformation of
           Transient Electronic Devices
    • Authors: Chi Hwan Lee; Seung‐Kyun Kang, Giovanni A. Salvatore, Yinji Ma, Bong Hoon Kim, Yu Jiang, Jae Soon Kim, Lingqing Yan, Dae Seung Wie, Anthony Banks, Soong Ju Oh, Xue Feng, Yonggang Huang, Gerhard Troester, John A. Rogers
      Abstract: Electronic systems that enable programmable transformation of functional behaviors by remote control or by autonomous responses to user‐defined circumstances create unusual engineering opportunities, where physical changes in the hardware induce desired changes in operation. This paper presents materials and device architectures for technologies of this type, in which localized microfluidic chemical etching of targeted constituent components in the electronics occurs in a sequential, selective manner. Custom circuits that include reconfigurable radio‐powered thermal actuators with analog amplifiers and square waveform generators illustrate the concepts. Unusual materials and designs for electronics enable systems with the ability for on‐demand, triggered functional transformations via the use of wireless microfluidic devices that initiate dissolution of targeted constituent components in a sequential, selective manner. Demonstration examples involve reconfigurable circuits for signal processing and data encryption.
      PubDate: 2015-07-14T10:13:33.181826-05:
      DOI: 10.1002/adfm.201502192
       
  • Luminescent Silicon Diatom Replicas: Self‐Reporting and Degradable
           Drug Carriers with Biologically Derived Shape for Sustained Delivery of
           Therapeutics
    • Authors: Shaheer Maher; Mohammed Alsawat, Tushar Kumeria, Dina Fathalla, Gihan Fetih, Abel Santos, Fawzia Habib, Dusan Losic
      Abstract: Current development of drug microcarriers is mainly based on spherical shapes, which are not biologically favorable geometries for complex interactions with biological systems. Scalable synthesis of drug carriers with nonspherical and anisotropic shapes featuring sustained drug‐releasing performances, biocompatibility, degradability, and sensing capabilities is challenging. These challenges are addressed in this work by employing Nature's optimized designs obtained from low‐cost diatomaceous earth mineral derived from single‐cell algae diatoms. Silica diatoms with unique shapes and 3D microcapsule morphology are converted into silicon diatom replicas with identical structure by a magnesiothermic reduction process. The results reveal that prepared silicon diatoms have a set of unique properties including favorable microcapsule structure with high surface area and micro/mesoporosity providing high drug loading, fast biodegradability, and intrinsic luminescence, which make them highly suitable for low‐cost production of advanced drug microcarriers. Their sustained drug release >30 days combined with self‐reporting function based on silicon luminescence properties using nonluminescent and luminescent drugs for intravitreal drug therapy is successfully demonstrated. These silicon diatoms offer promising potential toward scalable production of low‐cost and advanced microcarriers for broad medical therapies, including theranostics and microrobotic guided drug delivery devices. Toward the development of advanced self‐reporting microcarriers with biologically derived shapes for sustained drug delivery. Luminescent silicon diatoms replicas prepared from silica diatoms by a simple magnesiothermic reduction process feature outstanding drug delivery capacity, biodegradability, and self‐reporting capabilities, which make them outstanding candidates for advanced microcarriers for intravitreal and other medical therapies.
      PubDate: 2015-07-14T10:07:39.139248-05:
      DOI: 10.1002/adfm.201501249
       
  • Internal Biasing in Relaxor Ferroelectric Polymer to Enhance the
           Electrocaloric Effect
    • Authors: Xiaoshi Qian; Hui‐Jian Ye, Tiannan Yang, Wen‐Zhu Shao, Liang Zhen, Eugene Furman, Long‐Qing Chen, Qiming Zhang
      Abstract: The relaxor ferroelectric materials, because of their large and reversible electric field induced polarization, have been demonstrated to possess giant electrocaloric effect (ECE) over a broad temperature range, which are attractive for refrigeration with high energy efficiency and environmental friendliness. However, high electric fields are required to generate the giant ECE in these materials, posing challenge for these materials in practical cooling devices which also require high reliability and low cost. Here, a general approach is reported, for example, establishing an internal bias field in these relaxor ferroelectric polymers, to significantly improve ECE which can be induced at low electric fields. It is demonstrated that in a polymer blend (nanocomposite) with a properly controlled normal ferroelectric in nanophase dispersion in the relaxor polymer matrix, the charge neutrality in the blends can cause an internal biasing field, leading to more than 45% enhancement in the ECE at low electric field (≈50 MV m−1). This internal biasing approach provides a universal strategy to enhance other low field responses such as the electromechanical response in relaxor ferroelectrics. By internal biasing a relaxor ferroelectric polymer, it is demonstrated numerically and experimentally that both electrocaloric effect and electrocaloric coefficient can be enhanced. This approach provides a general route to enhance low‐field electrical performances of such square‐rule materials and thus pave the way to develop smart electroactive devices with better electrical reliability and safety.
      PubDate: 2015-07-14T10:07:31.617883-05:
      DOI: 10.1002/adfm.201501840
       
  • Vectorially Imprinted Hybrid Nanofilm for Acetylcholinesterase Recognition
    • Authors: Katharina J. Jetzschmann; Gyula Jágerszki, Decha Dechtrirat, Aysu Yarman, Nenad Gajovic‐Eichelmann, Hans‐Detlev Gilsing, Burkhard Schulz, Róbert E. Gyurcsányi, Frieder W. Scheller
      Abstract: Effective recognition of enzymatically active tetrameric acetylcholinesterase (AChE) is accomplished by a hybrid nanofilm composed of a propidium‐terminated self‐assembled monolayer (Prop‐SAM) which binds AChE via its peripheral anionic site (PAS) and an ultrathin electrosynthesized molecularly imprinted polymer (MIP) cover layer of a novel carboxylate‐modified derivative of 3,4‐propylenedioxythiophene. The rebinding of the AChE to the MIP/Prop‐SAM nanofilm covered electrode is detected by measuring in situ the enzymatic activity. The oxidative current of the released thiocholine is dependent on the AChE concentration from ≈0.04 × 10−6 to 0.4 × 10−6m. An imprinting factor of 9.9 is obtained for the hybrid MIP, which is among the best values reported for protein imprinting. The dissociation constant characterizing the strength of the MIP‐AChE binding is 4.2 × 10−7m indicating the dominant role of the PAS‐Prop‐SAM interaction, while the benefit of the MIP nanofilm covering the Prop‐SAM layer is the effective suppression of the cross‐reactivity toward competing proteins as compared with the Prop‐SAM. The threefold selectivity gain provided by i) the “shape‐specific” MIP filter, ii) the propidium‐SAM, iii) signal generation only by the AChE bound to the nanofilm shows promise for assessing AChE activity levels in cerebrospinal fluid. Recognition of tetrameric acetylcholinesterase (AChE), a potential marker of Alzheimer's disease, is accomplished by a hybrid nanofilm consisting of a propidium‐terminated self‐assembled monolayer (SAM) and an ultrathin electrosynthesized molecularly imprinted polymer (MIP) cover layer. A threefold selectivity gain is provided by i) the “shape‐specific” MIP filter, ii) the propidium‐SAM, and iii) signal generation only by the AChE bound to the nanofilm.
      PubDate: 2015-07-14T10:06:49.506618-05:
      DOI: 10.1002/adfm.201501900
       
  • Low‐Temperature Processable High‐Performance Electrochemically
           Deposited p‐Type Cuprous Oxides Achieved by Incorporating a Small
           Amount of Antimony
    • Authors: Seung Ki Baek; Yong Hun Kwon, Jae Hui Shin, Ho Seong Lee, Hyung Koun Cho
      Abstract: The development of an electrochemically robust method for the low‐temperature deposition of cuprous oxide (Cu2O) thin films with reliable and conductive p‐type characteristics could yield breakthroughs in earth abundant and ecofriendly all oxide‐based photoelectronic devices. The incorporation of the group‐V element antimony (Sb) in the solution‐based electrodeposition process has been investigated. A small amount of Sb (1.2 at%) in the Cu2O resulted in rapid nucleation and coalescence at the initial stage of electrochemical reaction, and finally made the surface morphology smooth in 2D. The growth behavior changed due to Sb addition and produced a strong diffraction intensity, single‐domain‐like diffraction patterns, and low angle tilt boundaries in the Cu2O:Sb film, implying extremely improved crystallinity. As a result, these films exhibited extraordinary optical transmittance and band‐to‐band photoluminescence emission as well as higher electrical conductivity. The Cu/Cu2O:Sb Schottky diode showed good rectifying characteristics and more sensible photoresponsibility. Highly stable p‐type cuprous oxide films with extremely improved optical performance are achieved by simple low‐temperature electrochemical deposition in the presence of antimony dopants. The Cu2O:Sb films demonstrate single‐domain‐like crystallinity with low angle tilted boundaries and exhibit semitransparent properties.
      PubDate: 2015-07-14T09:51:59.145884-05:
      DOI: 10.1002/adfm.201501323
       
  • Core–Shell Nanoparticles: Characterizing Multifunctional Materials
           beyond Imaging—Distinguishing and Quantifying Perfect and Broken
           Shells
    • Authors: Kristina Tschulik; Kamonwad Ngamchuea, Christoph Ziegler, Max Gregor Beier, Christine Damm, Alexander Eychmueller, Richard G. Compton
      Abstract: Core–shell nanoparticles (NPs) are amongst the most promising candidates in the development of new functional materials. Their fabrication and characterization are challenging, in particular when thin and intact shells are needed. To date no technique has been available that differentiates between intact and broken or cracked shells. Here a method is presented to distinguish and quantify these types of shells in a single cyclic voltammetry experiment by using the different electrochemical reactivities of the core and the shell material. A simple comparison of the charge measured during the stripping of the core material before and after the removal of the shell makes it possible to determine the quality of the shells and to estimate their thickness. As a proof‐of‐concept two multifunctional examples of core–shell NPs, Fe3O4@Au and Au@SnO2, are used. This general and original method can be applied whenever core and shell materials show different redox properties. Because billions of NPs are probed simultaneously and at a low cost, this method is a convenient new screening tool for the development of new multifunctional core–shell materials and is hence a powerful complementary technique or even an alternative to the state‐of‐the‐art characterization of core–shell NPs by TEM. A method of characterizing multifunctional materials beyond imaging is presented, distinguishing and quantifying intact and broken or cracked core–shell nanoparticles by using the different redox reactivities of the core and the shell material. Fe3O4@Au and Au@SnO2 samples are studied as two proof‐of‐concept systems.
      PubDate: 2015-07-14T09:49:48.425492-05:
      DOI: 10.1002/adfm.201501556
       
  • Photoinduced Colossal Magnetoresistance under Substantially Reduced
           Magnetic Field
    • Authors: Tomi Elovaara; Sayani Majumdar, Hannu Huhtinen, Petriina Paturi
      Abstract: The colossal magnetoresistive insulator to metal switching of almost nine orders of magnitude under the significantly reduced magnetic field is achieved by illumination for the low bandwidth manganite thin films. Similarly, by changing the measuring bias voltage through the sample the required magnetic field for insulator–metal transition can be further fine‐tuned. By applying a magnetic field of suitable strength, the samples can also be tuned to be extra sensitive to the illumination having colossal effect on the resistivity at low temperatures. This kind of utilizing of multiple external stimulants, which together change the properties of the material, could have significant impact on the new generation of phase‐change memories working under affordable conditions. The colossal magnetoresistive insulator‐to‐metal switching of almost nine orders of magnitude under significantly reduced magnetic field is achieved by illumination for low bandwidth manganite thin films. The magnetic field biasing amplifies the samples response to illumination, having colossal effect on the resistivity, which could have significant impact on the new generation phase‐change memories working under affordable conditions.
      PubDate: 2015-07-14T09:49:33.967171-05:
      DOI: 10.1002/adfm.201502233
       
  • Marker Pen Lithography for Flexible and Curvilinear On‐Chip Energy
           Storage
    • Authors: Qiu Jiang; Narendra Kurra, Husam N. Alshareef
      Abstract: On‐chip energy storage using microsupercapacitors can serve the dual role of supplementing batteries for pulse power delivery, and replacement of bulky electrolytic capacitors in ac‐line filtering applications. Despite complexity and processing costs, microfabrication techniques are being employed in fabricating a great variety of microsupercapacitor devices. Here, a simple, cost‐effective, and versatile strategy is proposed to fabricate flexible and curvilinear microsupercapacitors (MSCs). The protocol involves writing sacrificial ink patterns using commercial marker pens on rigid, flexible, and curvilinear substrates. It is shown that this process can be used in both lift‐off and etching modes, and the possibility of multistack design of active materials using simple pen lithography is demonstrated. As a prototype, this method is used to produce conducting polymer MSCs involving both poly(3,4‐ethylenedioxythiophene), polyaniline, and metal oxide (MnO2) electrode materials. Typical values of energy density in the range of 5–11 mWh cm−3 at power densities of 1–6 W cm−3 are achieved, which is comparable to thin film batteries and superior to the carbon and metal oxide based microsupercapacitors reported in the literature. The simplicity and broad scope of this innovative strategy can open up new avenues for easy and scalable fabrication of a wide variety of on‐chip energy storage devices. Marker pen ink is used for writing sacrificial patterns to fabricate energy storage devices on a variety of surfaces, including on‐chip, round, and curved surfaces, as micropower units capable of glowing a light‐emitting diode. This process can be used in both lift‐off and etching modes, and the possibility of multistack design of active materials using simple pen lithography is demonstrated.
      PubDate: 2015-07-14T09:08:25.2961-05:00
      DOI: 10.1002/adfm.201501698
       
  • Effective Controlling of Film Texture and Carrier Transport of a
           High‐Performance Polymeric Semiconductor by Magnetic Alignment
    • Authors: Guoxing Pan; Fei Chen, Lin Hu, Kejun Zhang, Jianming Dai, Fapei Zhang
      Abstract: The controlling of molecular orientation and structural ordering of organic semiconductors is crucial to achieve high performance electronic devices. In this work, large‐area highly oriented and ordered films of an excellent electron transporter Poly{[N,N′‐bis(2‐octyldodecyl)‐1,4,5,8‐naphthalenedicarboximide)‐2,6‐diyl]‐alt‐5,5′‐(2,2′‐bithiophene)} (P(NDI2OD‐T2)) are achieved by improved solution‐cast in high magnetic field. Microstructural characterizations reveal that the chain backbones of P(NDI2OD‐T2) are highly aligned along the applied magnetic field in the films. Based on the synchrotron‐based X‐ray diffraction analysis of the polymer films cast from different solvents, a mechanism which controls the alignment process is proposed, which emphasizes that molecular aggregates of P(NDI2OD‐T2) preformed in the solution initiate magnetic alignment and finally determine the degree of film texture. Furthermore, the time‐modulated magnetic field technique is utilized to effectively control the orientation of π‐conjugated plane of the backbones, thus the degree of face‐on molecular packing of P(NDI2OD‐T2) is enhanced significantly. Thin film transistors based on the magnetic‐aligned P(NDI2OD‐T2) films exhibit an enhancement of electron mobility by a factor of four compared to the unaligned devices, as well as a large mobility anisotropy of seven. Molecular orientation and film texture of n‐type semicrystalline polymer P(NDI2OD‐T2) at both in‐plane and out‐of‐plane directions is controlled effectively via the improved solution‐processings under high magnetic field. The mechanism on magnetically induced film growth is also elucidated. The magnetically aligned P(NDI2OD‐T2) films exhibit remarkably enhanced electron mobility and high mobility anisotropy.
      PubDate: 2015-07-14T09:08:16.079156-05:
      DOI: 10.1002/adfm.201500643
       
  • Hierarchical Tubular Structures Composed of Mn‐Based Mixed Metal
           Oxide Nanoflakes with Enhanced Electrochemical Properties
    • Authors: Yan Guo; Le Yu, Cheng‐Yang Wang, Zhan Lin, Xiong Wen (David) Lou
      Abstract: In this work, a simple strategy is developed to synthesize hierarchical tubular structures (HTS) of Mn‐based (Co‐Mn, Ni‐Mn, Cu‐Mn, Zn‐Mn) mixed metal oxides. The first step in the synthesis involves redox reaction mediated growth of nanoflakes on carbon nanofibers under hydrothermal conditions. After calcination in air, carbon nanofibers are removed and HTS of mixed metal oxides can be obtained with little structural deterioration. The resultant HTS are advantageous as electrodes for electrochemical energy storage. As an example, it is shown that the Co‐Mn‐HTS sample exhibits outstanding electrochemical performance as electrode materials for hybrid supercapacitors and lithium ion batteries. A general strategy is developed for the synthesis of hierarchical tubular structures of Mn‐based mixed metal oxides. The derived Co‐Mn mixed oxide hierarchical tubular structures manifest enhanced electrochemical properties as electrodes for both hybrid supercapacitors and lithium ion batteries.
      PubDate: 2015-07-14T09:07:57.563174-05:
      DOI: 10.1002/adfm.201501974
       
  • Study of Configuration Differentia and Highly Efficient, Deep‐Blue,
           Organic Light‐Emitting Diodes Based on Novel
           Naphtho[1,2‐d]imidazole Derivatives
    • Authors: Ming Liu; Xiang‐Long Li, Dong Cheng Chen, Zhongzhi Xie, Xinyi Cai, Gaozhan Xie, Kunkun Liu, Jianxin Tang, Shi‐Jian Su, Yong Cao
      Abstract: Two novel naphtho[1,2‐d]imidazole derivatives are developed as deep‐blue, light‐emitting materials for organic light‐emitting diodes (OLEDs). The 1H‐naphtho[1,2‐d]imidazole based compounds exhibit a significantly superior performance than the 3H‐naphtho[1,2‐d]imidazole analogues in the single‐layer devices. This is because they have a much higher capacity for direct electron‐injection from the cathode compared to their isomeric counterparts resulting in a ground‐breaking EQE (external quantum efficiency) of 4.37% and a low turn‐on voltage of 2.7 V, and this is hitherto the best performance for a non‐doped single‐layer fluorescent OLED. Multi‐layer devices consisting of both hole‐ and electron‐transporting layers, result in identically excellent performances with EQE values of 4.12–6.08% and deep‐blue light emission (Commission Internationale de l'Eclairage (CIE) y values of 0.077–0.115) is obtained for both isomers due to the improved carrier injection and confinement within the emissive layer. In addition, they showed a significantly better blue‐color purity than analogous molecules based on benzimidazole or phenanthro[9,10‐d]imidazole segments. Novel naphtho[1,2‐d]imidazole derivatives are developed as light‐emitting materials for OLEDs. 1H‐naphtho[1,2‐d]imidazole based compounds exhibit a significantly superior performance than their isomeric counterparts in the single‐layer devices owing to the much higher electron injection ability directly from the cathode. However, in the multi‐layer devices, uniformly high efficiencies are obtained with a desirable bluecolor that is more pure than that of their benzimidazole and phenanthro[9,10‐d]imidazole analogues.
      PubDate: 2015-07-14T09:07:42.29903-05:0
      DOI: 10.1002/adfm.201502163
       
  • Resistive Switching in Mott Insulators and Correlated Systems
    • Authors: Etienne Janod; Julien Tranchant, Benoit Corraze, Madec Querré, Pablo Stoliar, Marcelo Rozenberg, Tristan Cren, Dimitri Roditchev, Vinh Ta Phuoc, Marie‐Paule Besland, Laurent Cario
      Abstract: Resistive random access memories (ReRAM) form an emerging type of non‐volatile memories, based on an electrically driven resistive switching (RS) of an active material. This Feature Article focuses on a broad class of ReRAM where the active material is a Mott insulator or a correlated system. These materials can indeed undergo various insulator‐to‐metal transitions (IMT) in response to external perturbations such as electronic doping or temperature. These IMT explain most of resistive switching observed in correlated insulators as, for example, the Joule heating induced RS in VO2. The main part of this Feature Article is dedicated to a new mechanism of resistive switching recently unveiled in canonical Mott insulators such as (V1‐xCrx)2O3, NiS2‐xSex and AM4Q8 (A = Ga, Ge; M = V, Nb, Ta, Mo; Q = S, Se, Te). In these narrow gap Mott insulators, an electronic avalanche breakdown induces a resistive switching, first volatile above a threshold electric field of a few kV/cm and then non‐volatile at higher field. The low resistance state is related to the creation of granular conductive filaments, which, in the non‐volatile case, can be erased by means of Joule heating. ReRAM devices based on this new type of out of equilibrium Mott insulator‐to‐metal transition display promising performances. The different types of resistive switching encountered in Mott insulators or correlated systems are discussed. Resistive switching that is well explained by insulator‐to‐metal transitions driven by doping or temperature is first described. The new mechanism of resistive switching driven by electric field recently unveiled in canonical Mott insulators is also addressed.
      PubDate: 2015-07-14T08:45:18.116173-05:
      DOI: 10.1002/adfm.201500823
       
  • Development of a Multifunctional Platform Based on Strong, Intrinsically
           Photoluminescent and Antimicrobial Silica‐Poly(citrates)‐Based
           Hybrid Biodegradable Elastomers for Bone Regeneration
    • Authors: Yuzhang Du; Meng Yu, Juan Ge, Peter X. Ma, Xiaofeng Chen, Bo Lei
      Abstract: Biodegradable biomaterials with intrinsically multifunctional properties such as high strength, photoluminescent ability (bioimaging monitoring), and antimicrobial activity (anti‐infection), as well as high osteoblastic differentiation ability, play a critical role in successful bone tissue regeneration. However, fabricating a biomaterial containing all these functions is still a challenge. Here, urethane cross‐linked intrinsically multifunctional silica‐poly(citrate) (CMSPC)‐based hybrid elastomers are developed by first one‐step polymerization and further chemical crosslinked using isocyanate. CMSPC hybrid elastomers demonstrate a high modulus of 976 ± 15 MPa, which is superior compared with most conventional poly(citrate)‐based elastomers. Hybrid elastomers show strong and stable intrinsic photoluminescent ability (emission 400–600 nm) due to the incorporation of silica phase. All elastomers exhibit high inherent antibacterial properties against Staphylococcus aureus. In addition, CMSPC hybrid elastomers significantly enhance the proliferation and metabolic activity of osteoblasts (MC3T3‐E1). CMSPC hybrid elastomers significantly promote the osteogenic differentiation of MC3T3‐E1 by improving alkaline phosphatase activity and calcium biomineralization deposits, as well as expressions of osteoblastic genes. These hybrid elastomers also show a minimal inflammatory response indicated by subcutaneous transplantation in vivo. These optimized structure and multifunctional properties make this hybrid elastomer highly promising for bone tissue regeneration and antiinfection and bioimaging applications. A multifunctional platform based on strong, intrinsically photoluminescent and antimicrobial silica‐poly(citrates)‐based hybrid elastomers is developed for bone tissue regeneration. The silica‐based hybrid elastomers demonstrate a strong mechanical strength of 976 ± 15 MPa (modulus), stable intrinsic photoluminescent ability, inherent antibacterial properties against Staphylococcus aureus, the osteogenic differentiation of cells, as well as the minimal inflammatory response.
      PubDate: 2015-07-14T08:45:00.20053-05:0
      DOI: 10.1002/adfm.201501712
       
  • Bioinspired, Stimuli‐Responsive, Multifunctional Superhydrophobic
           Surface with Directional Wetting, Adhesion, and Transport of Water
    • Authors: Yang Liu; Xiaowen Wang, Bin Fei, Huawen Hu, Chuilin Lai, John H. Xin
      Abstract: A novel smart stimuli responsive surface can be fabricated by the subsequent self‐assembly of the graphene monolayer and the TiO2 nanofilm on various substrates, that is, fabrics, Si wafers, and polymer thin films. Multiscale application property can be achieved from the interfacial interaction between the hierarchical graphene/TiO2 surface structure and the underlying substrate. The smart surface possesses superhydrophobic property as a result of its hierarchical micro‐ to nanoscale structural roughness. Upon manipulating the UV induced hydrophilic conversion of TiO2 on graphene/TiO2 surface, smart surface features, such as tunable adhesiveness, wettability, and directional water transport, can be easily obtained. The existence of graphene indeed enhances the electron–hole pair separation efficiency of the photo‐active TiO2, as the time required for the TiO2 superhydrophilic conversion is largely reduced. Multifunctional characteristics, such as gas sensing, droplet manipulation, and self‐cleaning, are achieved on the smart surface as a result of its robust superhydrophobicity, tunable wettability, and high photo‐catalytic activity. It is also revealed that the superhydrophilic conversion of TiO2 is possibly caused by the atomic rearrangement of TiO2 under UV radiation, as a structural transformation from {101} to {001} is observed after the UV treatment. A smart stimuli‐responsive surface is fabricated based on a graphene and TiO2 nanofilm. The bioinspired hierarchical dual roughness endows the surface with superhydrophobicity, while tunable adhesiveness, wettability, and directionality are achieved utilizing the UV‐induced interaction between graphene and TiO2. This novel multifunctional smart surface design provides a potent insight for overcoming the evolving material challenge.
      PubDate: 2015-07-14T08:44:49.000023-05:
      DOI: 10.1002/adfm.201501705
       
  • Controlling the Chromaticity of Small‐Molecule Light‐Emitting
           Electrochemical Cells Based on TIPS‐Pentacene
    • Authors: Michael D. Weber; Matthias Adam, Rik R. Tykwinski, Rubén D. Costa
      Abstract: This work demonstrates a novel proof‐of‐concept to implement pentacene derivatives as emitters for the third generation of light‐emitting electrochemical cells based on small‐molecules (SM‐LECs). Here, a straightforward procedure is shown to control the chromaticity of pentacene‐based lighting devices by means of a photoinduced cycloaddition process of the 6,13‐bis(triisopropylsilylethynyl) (TIPS)‐pentacene that leads to the formation of anthracene‐core dimeric species featuring a high‐energy emission. Without using the procedure, SM‐LECs featuring deep‐red emission with Commission Internationale d'Eclairage (CIE) coordinates of x = 0.69/y = 0.31 and irradiance of 0.4 μW cm−2 are achieved. After a careful optimization of the cycloaddition process, warm white devices with CIE coordinates of x = 0.36/y = 0.38 and luminances of 10 cd m−2 are realized. Here, the mechanism of the device is explained as a host–guest system, in which the dimeric species acts as the high‐energy band gap host and the low‐energy bandgap TIPS‐pentacene is the guest. To the best of the knowledge, this work shows the first warm white SM‐LECs. Since this work is based on the archetypal TIPS‐pentacene and the photoinduced cycloaddition process is well‐knownfor any pentacenes, this proof‐of‐concept could open a new way to use these compounds for developing white lighting sources. TIPS‐pentacene has been tested as an emitter in small‐molecule light‐emitting electrochemical cells (SM‐LECs). The formation of high‐energy band gap species via photoinduced cycloaddition process has been exploited to control the device chromaticity from red to white. As such, this work provides a proof‐of‐concept that opens a new avenue to fabricate white lighting sources based on pentacene derivatives.
      PubDate: 2015-07-14T08:44:38.089162-05:
      DOI: 10.1002/adfm.201501326
       
  • Two‐Dimensional Transition Metal Dichalcogenides in Biosystems
    • Authors: Kourosh Kalantar‐zadeh; Jian Zhen Ou, Torben Daeneke, Michael S. Strano, Martin Pumera, Sally L. Gras
      Abstract: The intriguing properties of two‐dimensional transition metal dichalcogenides (2D TMDCs) have led to a significant body of fundamental research and rapid uptake of these materials in many applications. Specifically, 2D TMDCs have shown great potential in biological systems due to their tunable electronic characteristics, unique optical properties, stability in aqueous environments, large surface area that can be manipulated and functionalized as well as an intercalatable layered structure, and low levels of toxicity. Here, the characteristics and use of 2D TMDCs for biological applications are reviewed and future possibilities for these materials in biological systems are outlined. Two‐dimensional transition metal dichalcogenides demonstratea plethora of unique properties including tunable electronic and optical characteristics, stability in aqueous environments, large surface areas that can be manipulated and functionalized and intercalatable layered structures. Relatively low levels of toxicity and facile synthesis routes make these materials suitable for future biological systems.
      PubDate: 2015-07-14T08:21:32.898274-05:
      DOI: 10.1002/adfm.201500891
       
  • Epitaxy on Demand
    • Authors: Maarten Nijland; Sean Thomas, Mark A. Smithers, Nirupam Banerjee, Dave H. A. Blank, Guus Rijnders, Jing Xia, Gertjan Koster, Johan E. ten Elshof
      Abstract: Perovskite oxide heteroepitaxy is realized on the top of inorganic nanosheets that are covering the amorphous oxide surfaces of Si substrates. Utilizing pulsed laser deposition, thin films of SrRuO3 in a (001)pc and (110)pc orientation on nanosheets of Ca2Nb3O10 and Ti0.87O2 are grown, respectively. The two types of nanosheets are patterned to locally tailor the crystallographic orientation and properties of SrRuO3. The success of our approach is demonstrated by electron backscatter diffraction and spatial magnetization maps. An unprecedented control of perovskite film growth on arbitrary substrates is illustrated in this work, and the methods that are developed to deposit SrRuO3 thin films are a viable starting point for growth of artificial heteroepitaxial thin films that require a bottom electrode. Control is not just reached in the direction of film growth, as the crystal orientation and film properties are regulated laterally on the surface of micropatterned nanosheets. Local control of magnetic properties is illustrated, which holds out prospects for the fabrication of next‐generation devices like noncollinear magnetic random access memories. Perovskite thin films are deposited on Si substrates covered with inorganic nano­sheets of Ca2Nb3O10 or Ti0.87O2. These nanosheets are used to control the nucleation of films that consist of a SrTiO3 buffer layer and a SrRuO3 top layer. The two types of nanosheets are micropatterned to locally tailor the crystallographic orientation, allowing lateral control of the magnetic properties of SrRuO3.
      PubDate: 2015-07-14T08:21:17.977642-05:
      DOI: 10.1002/adfm.201501483
       
  • Bioinspired Blood Compatible Surface Having Combined Fibrinolytic and
           Vascular Endothelium‐Like Properties via a Sequential
           Coimmobilization Strategy
    • Authors: Wenjun Zhan; Xiujuan Shi, Qian Yu, Zhonglin Lyu, Limin Cao, Hui Du, Qi Liu, Xin Wang, Gaojian Chen, Dan Li, John L. Brash, Hong Chen
      Abstract: Developing surfaces with antithrombotic properties is of great interest for the applications of blood‐contacting biomaterials and medical devices. It is promising to coimmobilize two or more biomolecules with different and complementary functions to improve blood compatibility. However, the general one‐pot strategy usually adopted by previous studies suffers the problems of inevitable competition between diverse biomolecules and uncontrollability of the relative quantities of the immobilized biomolecules. To solve these problems, a new sequential coimmobilization strategy is proposed and applied to fabricate a blood compatible surface. Polyurethane surface is modified with a copolymer, poly(2‐hydroxyethyl methacrylate‐co‐1‐adamantan‐1‐ylmethyl methacrylate), which serves as a linker‐spacer for sequential attachment of two functional molecules, a hexapeptide containing REDV (Arg‐Glu‐Asp‐Val) sequence, and a modified cyclodextrin bearing 7 lysine ligands, through covalent bonding and host–guest interaction, respectively. The resulting surface combines the antithrombogenic properties of the vascular endothelium and the clot lysing properties of the fibrinolytic system. Importantly, neither of the two functions of REDV peptide and lysine is compromised by the presence of the other, suggesting the enhanced blood compatibility. These results suggest a new strategy to engineer multifunctional surfaces by coimmobilization of bioactive molecules having unique functionalities. Bioinspired blood compatible surface is developed with the capability to both lyse nascent clots and promote endothelialization. The surface is fabricated by sequential coimmobilization of two biomolecules with respective properties via host–guest interaction and covalent bonding, respectively. Neither function of the two biomolecules is compromised by the presence of the other.
      PubDate: 2015-07-14T08:21:04.697035-05:
      DOI: 10.1002/adfm.201501642
       
  • The Interplay of Modulus, Strength, and Ductility in Adhesive Design Using
           Biomimetic Polymer Chemistry
    • Authors: Heather J. Meredith; Jonathan J. Wilker
      Abstract: High‐performance adhesives require mechanical properties tuned to demands of the surroundings. A mismatch in stiffness between substrate and adhesive leads to stress concentrations and fracture when the bonding is subjected to mechanical load. Balancing material strength versus ductility, as well as considering the relationship between adhesive modulus and substrate modulus, creates stronger joints. However, a detailed understanding of how these properties interplay is lacking. Here, a biomimetic terpolymer is altered systematically to identify regions of optimal bonding. Mechanical properties of these terpolymers are tailored by controlling the amount of a methyl methacrylate stiff monomer versus a similar monomer containing flexible poly(ethylene glycol) chains. Dopamine methacrylamide, the cross‐linking monomer, is a catechol moiety analogous to 3,4‐dihydroxyphenylalanine, a key component in the adhesive proteins of marine mussels. Bulk adhesion of this family of terpolymers is tested on metal and plastic substrates. Incorporating higher amounts of poly(ethylene glycol) into the terpolymer introduces flexibility and ductility. By taking a systematic approach to polymer design, the region in which material strength and ductility are balanced in relation to the substrate modulus is found, thereby yielding the most robust joints. A mussel mimicking adhesive terpolymer is synthetically tuned to identify the composition at which the material becomes toughened. How the strength, ductility, and modulus of an adhesive interact to create the most robust joints between plastic and metal substrates is shown in this systematic study.
      PubDate: 2015-07-14T08:20:20.256104-05:
      DOI: 10.1002/adfm.201501880
       
  • Functionalized Graphene Superlattice as a Single‐Sheet Solar Cell
    • Authors: Huashan Li; David A. Strubbe, Jeffrey C. Grossman
      Abstract: In‐plane heterostructure engineering provides unique opportunities to control device properties. Here, a single‐sheet solar cell made of a graphene sheet functionalized into 1D channels is explored. Compared to vertical heterostructure architectures based on 2D materials, the single‐sheet solar cell shows potential for improved robustness against defects, enhancement of polaron dissociation, extra freedom for functionalization, and coverage of the entire solar spectrum. The partition width, device length, and functionalizations can be tuned independently to optimize the key optoelectronic properties for photovoltaic performance. The device performance of a single‐sheet solar cell made of graphene sheet functionalized into 1D stripes is analyzed using a combination of ab initio simulation and scaling analysis, as a prototype system of in‐plane heterostructure engineering. The results suggests highly correlated optoelectronic properties can be optimized simultaneously via independent tuning of the partition width, device length, and functionalizations.
      PubDate: 2015-07-14T08:20:13.054307-05:
      DOI: 10.1002/adfm.201501906
       
  • 3D Nanocomposites of Covalently Interconnected Multiwalled Carbon
           Nanotubes with SiC with Enhanced Thermal and Electrical Properties
    • Authors: Lakshmy Pulickal Rajukumar; Manuel Belmonte, John Edward Slimak, Ana Laura Elías, Eduardo Cruz‐Silva, Nestor Perea‐López, Aaron Morelos‐Gómez, Humberto Terrones, Morinobu Endo, Pilar Miranzo, Mauricio Terrones
      Abstract: Synthesizing 3D carbon nanotube (CNT) networks with multifunctional characteristics has stimulated the interest from the scientific community since the 1990s. Here, the fabrication of a novel composite material consisting of 3D covalently interconnected multiwalled CNT with silicon carbide (SiC) nano and microparticles is reported. The material is synthesized by a two‐step process involving the coating of CNT with silicon oxide (SiO x ) via chemical routes, followed by spark plasma sintering (SPS). SPS enables carbothermal reduction of SiOx and subsequent densification of the material into 3D composite blocks. Covalent interconnections of CNT are facilitated by a carbon diffusion process resulting in SiC formation as SiOx coated CNT are subjected to high temperatures. The presence of SiC in the sintered composite has been confirmed by Raman spectroscopy, as well as through energy filtered transmission electron microscopy maps. Interestingly, the 3D CNT composite exhibits high thermal conductivity (16.72 W m−1 K−1); and also a semiconducting behavior with an electron hopping mechanism associated to a 3D variable range hopping model. These findings demonstrate that it is indeed possible to fabricate SiC–CNT composites with enhanced physical properties that can be used as multifunctional materials. A 3D interconnected carbon nanotube (CNT)–silicon carbide (SiC) composite is fabricated by coating the tubes with silica followed by spark plasma sintering at high temperature and pressure. The resultant SiC–CNT composite possesses excellent thermal and electrical conductivity owing to the covalent 3D network. This is a novel route to produce multifunctional CNT‐based composites.
      PubDate: 2015-07-14T08:07:35.416682-05:
      DOI: 10.1002/adfm.201501696
       
  • How Does Moisture Affect the Physical Property of Memristance for
           Anionic–Electronic Resistive Switching Memories?
    • Authors: Felix Messerschmitt; Markus Kubicek, Jennifer L. M. Rupp
      Abstract: Memristors based on anionic–electronic resistive switches represent a promising alternative to transistor‐based memories because of their scalability and low power consumption. To date, studies on resistive switching have focused on oxygen anionic or electronic defects leaving protonic charge‐carrier contributions out of the picture despite the fact that many resistive switching oxides are well‐established materials in resistive humidity sensors. Here, the way memristance is affected by moisture for the model material strontium titanate is studied. First, characterize own‐processed Pt SrTiO3‐δ Pt bits via cyclic voltammetry under ambient conditions are thoroughly characterized. Based on the high stability of a non‐volatile device structures the impact of relative humidity to the current–voltage profiles is then investigated. It is found that Pt SrTiO3‐δ Pt strongly modifies the resistance states by up to 4 orders of magnitude as well as the device's current–voltage profile shape, number of crossings, and switching capability with the level of moisture exposure. Furthermore, a reversible transition from classic memristive behavior at ambient humidity to a capacitively dominated one in dry atmosphere for which the resistive switching completely vanishes is demonstrated for the first time. The results are discussed in relation to the changed Schottky barrier by adsorbed surface water molecules and its interplay with the charge transfer in the oxide. The memristive response in anionic‐electronic resistive switching devices is incontestably related to the humidity level of the surrounding air. Water molecules present in the air are incorporated into the oxide thin film and interfere strongly with the space‐charge region at the metal oxide interface, thus, affecting the resistive switching of the device operating under high local electric fields.
      PubDate: 2015-07-14T08:07:26.352491-05:
      DOI: 10.1002/adfm.201501517
       
  • Localization of Au Nanoclusters on Layered Double Hydroxides Nanosheets:
           Confinement‐Induced Emission Enhancement and
           Temperature‐Responsive Luminescence
    • Authors: Rui Tian; Shitong Zhang, Mingwan Li, Yuqiong Zhou, Bo Lu, Dongpeng Yan, Min Wei, David G. Evans, Xue Duan
      Abstract: Gold nanoclusters (Au NCs) stand for a new type of fluorescent nanomaterials with outstanding optical properties due to their discrete electronic energy and direct electron transition. However, relative low quantum yield (QY) of Au NCs in aqueous or solid state has limited their photofunctional applications. To improve the fluorescent performances of Au NCs and find an effective approach for the fabrication of Au NCs‐based films, in this work, Au NCs are localized onto 2D layered double hydroxides (LDHs) nanosheets via a layer‐by‐layer assembly process; the as‐fabricated (Au NCs/LDH)n ultrathin films (UTFs) show an ordered and dense immobilization of Au NCs. The localization and confinement effects imposed by LDH nanosheets induce significantly increased emissive Au(I) units as confirmed by X‐ray photoelectron spectroscopy and periodic density functional theoretical simulation, which further results in promoted QY (from 2.69% to 14.11%) and prolonged fluorescence lifetime (from 1.84 µs to 14.67 µs). Moreover, the ordered (Au NCs/LDH)n UTFs exhibit well‐defined temperature‐dependent photoluminescence (PL) and electrochemiluminescence (ECL) responses. Therefore, this work supplies a facile strategy to achieve the immobilization of Au NCs and obtain Au NCs‐based thin films with high luminescent properties, which have potential applications in PL and ECL temperature sensors. An ultrathin film material is fabricated based on the localization of Au nanoclusters onto layered double hydroxide nanosheets, and exhibits temperature‐responsive photoluminescence and electrochemiluminescence performances with high sensitivity and stability.
      PubDate: 2015-07-08T01:24:31.753821-05:
      DOI: 10.1002/adfm.201501433
       
  • Plasmonic‐Induced Photon Recycling in Metal Halide Perovskite Solar
           Cells
    • Authors: Michael Saliba; Wei Zhang, Victor M. Burlakov, Samuel D. Stranks, Yao Sun, James M. Ball, Michael B. Johnston, Alain Goriely, Ulrich Wiesner, Henry J. Snaith
      Abstract: Organic–inorganic metal halide perovskite solar cells have emerged in the past few years to promise highly efficient photovoltaic devices at low costs. Here, temperature‐sensitive core–shell Ag@TiO2 nanoparticles are successfully incorporated into perovskite solar cells through a low‐temperature processing route, boosting the measured device efficiencies up to 16.3%. Experimental evidence is shown and a theoretical model is developed which predicts that the presence of highly polarizable nanoparticles enhances the radiative decay of excitons and increases the reabsorption of emitted radiation, representing a novel photon recycling scheme. The work elucidates the complicated subtle interactions between light and matter in plasmonic photovoltaic composites. Photonic and plasmonic schemes such as this may help to move highly efficient perovskite solar cells closer to the theoretical limiting efficiencies. Adding plasmonic core–shell nanoparticles (Ag@TiO2) to perovskite solar cells is shown to improve the photo­current and thus the overall efficiency. A theoretical model, introducing a novel photon recycling scheme, predicts that highly polarizable nanoparticles act as antennas for light re‐emitted from radiative recombination. The work elucidates the complicated, subtle interactions between light and matter in plasmonic photovoltaic composites.
      PubDate: 2015-07-08T01:23:43.106382-05:
      DOI: 10.1002/adfm.201500669
       
  • Carbon and Graphene Quantum Dots for Optoelectronic and Energy Devices: A
           Review
    • Authors: Xiaoming Li; Muchen Rui, Jizhong Song, Zihan Shen, Haibo Zeng
      Abstract: As new members of carbon material family, carbon and graphene quantum dots (CDs, GQDs) have attracted tremendous attentions for their potentials for biological, optoelectronic, and energy related applications. Among these applications, bio‐imaging has been intensively studied, but optoelectronic and energy devices are rapidly rising. In this Feature Article, recent exciting progresses on CD‐ and GQD‐based optoelectronic and energy devices, such as light emitting diodes (LEDs), solar cells (SCs), photodetctors (PDs), photocatalysis, batteries, and supercapacitors are highlighted. The recent understanding on their microstructure and optical properties are briefly introduced in the first part. Some important progresses on optoelectronic and energy devices are then addressed as the main part of this Feature Article. Finally, a brief outlook is given, pointing out that CDs and GQDs could play more important roles in communication‐ and energy‐functional devices in the near future. Carbon dots and graphene quantum dots have been investigated for several years and researchers' interest is moving from photoluminescence towards device applications. In this Feature Article, applications in optoelectronic and energy devices of carbon dots and graphene quantum dots are summarized, as well as their optical properties. Future directions, challenges, and other possible applications are also put forward.
      PubDate: 2015-07-06T10:11:26.947284-05:
      DOI: 10.1002/adfm.201501250
       
  • Design and Integration in Electro‐Optic Devices of Highly Efficient
           and Robust Red‐NIR Phosphorescent Nematic Hybrid Liquid Crystals
           Containing [Mo6I8(OCOCnF2n+1)6]2− (n = 1, 2, 3) Nanoclusters
    • Authors: Marianne Prévôt; Maria Amela‐Cortes, Sumann K. Manna, Ronan Lefort, Stéphane Cordier, Hervé Folliot, Laurent Dupont, Yann Molard
      Abstract: By combining [Mo6I8(C n F2n+1COO)6]2‐ (n = 1, 2, 3) nanocluster units with liquid crystalline ammonium cations, a new series of hybrid materials is developed that show a nematic liquid crystal phase, the most fluid of all LC phase, on a large range of temperatures including room temperature. The photophysical studies performed in the LC state show that these self‐assembled hybrid materials emit in the red‐NIR with absolute quantum yields up to 0.7 and show a very good photostability under continuous irradiation. They are further integrated up to 20 wt% in E7, a well‐known nematic commercial LC mixture. Mixtures are investigated in terms of homogeneity and stability to select the best suitable candidate for the design of electro‐controlled devices. Studies of optical switching, contrast, viscosity, and behavior toward an electrical stimulus demonstrate the high potential of these hybrid materials in the fields of photonic or optoelectronic. The functionalization of highly phosphorescent [Mo6I8(C n F2n+1COO)6]2− (n = 1, 2, 3) nanocluster anionic units with appropriate ammonium cations, leads to the formation of the most fluid of all liquid crystalline phases: the nematic phase. The excellent photostability of these hybrid materials makes them suitable candidates for the design of electro‐optical devices directed toward photonic or optoelectronic applications.
      PubDate: 2015-07-06T10:08:56.202728-05:
      DOI: 10.1002/adfm.201501876
       
  • Self‐Assembling Prodrugs by Precise Programming of Molecular
           Structures that Contribute Distinct Stability, Pharmacokinetics, and
           Antitumor Efficacy
    • Authors: Hangxiang Wang; Haiyang Xie, Jianguo Wang, Jiaping Wu, Xueji Ma, Lingling Li, Xuyong Wei, Qi Ling, Penghong Song, Lin Zhou, Xiao Xu, Shusen Zheng
      Abstract: The availability of precisely modulated chemical modifications dramatically affects the physicochemical properties of pristine drugs and should facilitate the amphiphilic self‐assembly of prodrugs into supramolecular nanoprodrugs (SNPs). However, rationally designing such prodrugs to achieve favorable clinical outcomes still remains a challenge. Here, a library of prodrugs through site‐specific attachment of a variety of lipophilic moieties to the antitumor agent SN‐38 (7‐ethyl‐10‐hydroxycamptothecin) is constructed. Taking advantage of the role of hydroxyl groups as solvophilic moieties, these prodrugs exhibit self‐assembly in aqueous environments, allowing for the identification of five prodrugs capable of self‐assembling into SNPs at high drug concentrations. Importantly, in vivo studies demonstrate that the antitumor activity of the SNPs correlates well with their stability and long‐term circulation. In addition, the modular feature of this SNP design strategy offers the opportunity to readily incorporate additional valuable functionalities (e.g., tumor‐specific targeting ligands) to the particle surface, which is further exploited to improve antitumor efficacy in mouse xenograft models. Thus, this structure‐based reconstruction of SN‐38 molecules significantly improves the potency of SNPs for clinical use. These results also provide novel mechanistic insights into the rational design of prodrugs. A novel carrier‐free drug delivery platform relying on amphiphilic self‐assembly of pure prodrugs is successfully constructed by rational engineering of antitumor agent 7‐ethyl‐10‐hydroxycamptothecin (SN‐38). Specifically, the prodrugs modified with polyunsaturated fatty acids exhibit enhanced stability, which contributes to their superior antitumor activity in vivo. Besides, additional valuable functionalities such as tumor‐specific ligands can be readily incorporated to improve antitumor efficacy.
      PubDate: 2015-07-06T10:08:43.814496-05:
      DOI: 10.1002/adfm.201501953
       
  • In Situ Formation of Conductive Metal Sulfide Domain in Metal Oxide
           Matrix: An Efficient Way to Improve the Electrochemical Activity of
           Semiconducting Metal Oxide
    • Authors: In Young Kim; Jiyoon Seo, Seung Mi Oh, Sharad B. Patil, Seong‐Ju Hwang
      Abstract: A new effective way to improve the electrochemical activity of semiconducting metal oxide is developed by the in situ formation of conductive metal sulfide domain in the metal oxide matrix. The Li0.96Ti1.08S2−Li4Ti5O12 nanocomposites with tunable compositions and electrical properties are synthesized by the reaction of Li4Ti5O12 with CS2 at elevated temperature. The resulting incorporation of conductive Li0.96Ti1.08S2 domain in the Li4Ti5O12 matrix is effective in enhancing the electrical conductivity and electrode activity of semiconducting lithium titanate. As anode materials for lithium ion batteries, the obtained Li0.96Ti1.08S2−Li4Ti5O12 nanocomposites show much greater discharge capacity and better rate characteristics than does the pristine Li4Ti5O12. The usefulness of the present method is further evidenced from the improvement of the electrochemical activity of semiconducting CsTi2NbO7 after the reaction with CS2. The present study clearly demonstrates the in situ formation of conductive metal sulfide domain using CS2 liquid can provide an efficient and universal way to improve the electrode functionality of semiconducting metal oxide. An effective synthetic route to novel metal sulfide−metal oxide nanocomposites is developed on the basis of the in situ formation of conductive metal sulfide domains in metal oxide matrix. The resulting Li0.96Ti1.08S2−Li4Ti5O12 nanocomposites show promising functionality as anode materials for lithium secondary batteries with excellent rate characteristics, underscoring the usefulness of the present in situ composite formation route.
      PubDate: 2015-07-06T10:08:30.734831-05:
      DOI: 10.1002/adfm.201501478
       
  • The Unique Structural Evolution of the O3‐Phase Na2/3Fe2/3Mn1/3O2
           during High Rate Charge/Discharge: A Sodium‐Centred Perspective
    • Authors: Neeraj Sharma; Elena Gonzalo, James C. Pramudita, Man Huon Han, Helen E. A. Brand, Judy N. Hart, Wei Kong Pang, Zaiping Guo, Teófilo Rojo
      Abstract: The development of new insertion electrodes in sodium‐ion batteries requires an in‐depth understanding of the relationship between electrochemical performance and the structural evolution during cycling. To date in situ synchrotron X‐ray and neutron diffraction methods appear to be the only probes of in situ electrode evolution at high rates, a critical condition for battery development. Here, the structural evolution of the recently synthesized O3‐phase of Na2/3Fe2/3Mn1/3O2 is reported under relatively high current rates. The evolution of the phases, their lattice parameters, and phase fractions, and the sodium content in the crystal structure as a function of the charge/discharge process are shown. It is found that the O3‐phase persists throughout the charge/discharge cycle but undergoes a series of two‐phase and solid‐solution transitions subtly modifying the sodium content and atomic positions but keeping the overall space‐group symmetry (structural motif). In addition, for the first time, evidence of a structurally characterized region is shown that undergoes two‐phase and solid‐solution phase transitions simultaneously. The Mn/Fe–O bond lengths, c lattice parameter evolution, and the distance between the Mn/FeO6 layers are shown to concertedly change in a favorable manner for Na+ insertion/extraction. The exceptional electrochemical performance of this electrode can be related in part to the electrode maintaining the O3‐phase throughout the charge/discharge process. O3‐Na2/3Fe2/3Mn1/3O2 undergoes sequential reactions during charge and discharge but maintains the same O3 structural motif. This has direct implications on the electrochemical performance of this polymorph. Rietveld refinements and calculations are used to show the sodium content evolution of this cathode in a functioning sodium‐ion battery.
      PubDate: 2015-07-06T02:00:22.256982-05:
      DOI: 10.1002/adfm.201501655
       
  • Engineering the Magnetic Dipolar Interactions in 3D Binary Supracrystals
           Via Mesoscale Alloying
    • Authors: Zhijie Yang; Jingjing Wei, Pierre Bonville, Marie‐Paule Pileni
      Abstract: Inspired by metallic alloys in atomic solids, two distinct metallic nanoparticles are used, considered as “artificial metal atoms,” to engineer ordered binary nanoparticle alloys at the mesoscale, called binary supracrystals. Here, ferromagnetic 7.2 nm Co nanoparticles are used as large “A” site particles, while either ferromagnetic 4.6 nm Co or nonmagnetic 4.0 nm Ag nanoparticles are used as small “B” site particles to fabricate long‐range ordered binary supracrystals with a stoichiometry of AB2 and AB13. The interparticle distances between 7.2 nm Co nanoparticles within the Co/Ag binary supracrystals can be tuned by a control of crystal structure from AB2 (CoAg2) to AB13 (CoAg13). A decrease of magnetic coupling between Co nanoparticles is observed as the Co–Co interparticle distance increases. Furthermore, by alloying 7.2 and 4.6 nm Co nanoparticles to form AB2 (CoCo2) binary supracrystals, a collective magnetic behavior of these two particle types, due to the dipolar interaction, is evidenced by observing a single peak in the zero‐field‐cooled magnetization curve. Compared with the CoAg2 binary supracrystals, a spin orientation effect in sublattice that reduces the dipolar interactions in the supracrystals is uncovered in CoCo2 binary supracrystals. 3D magnetic binary supracrystals are fabricated, and the magnetic dipolar interactions are found to be controllable by the binary structure and the type of small nanoparticles. The presence of small ferromagnetic nanoparticles can lead to a weaker dipolar interaction than the insertion of nonmagnetic ones.
      PubDate: 2015-07-03T06:10:26.020456-05:
      DOI: 10.1002/adfm.201501499
       
  • Dye Encapsulated Metal‐Organic Framework for Warm‐White LED
           with High Color‐Rendering Index
    • Authors: Yuanjing Cui; Tao Song, Jiancan Yu, Yu Yang, Zhiyu Wang, Guodong Qian
      Abstract: A strategy by encapsulating organic dyes into the pores of a luminescent metal‐organic framework (MOF) is developed to achieve white‐light‐emitting phosphor. Both the red‐light emitting dye 4‐(p‐dimethylaminostyryl)‐1‐methylpyridinium (DSM) and the green‐light emitting dye acriflavine (AF) are encapsulated into a blue‐emitting anionic MOF ZJU‐28 through an ion‐exchange process to yield the MOF⊃dye composite ZJU‐28⊃DSM/AF. The emission color of the obtained composite can be easily modulated by simply adjusting the amount and component of dyes. With careful adjustment of the relative concentration of the dyes DSM and AF, the resulting ZJU‐28⊃DSM/AF (0.02 wt% DSM, 0.06 wt% AF) exhibits a broadband white emission with ideal CIE coordinates of (0.34, 0.32), high color‐rendering index value of 91, and moderate correlated color temperature value of 5327 K. Such a strategy can be easily expanded to other luminescent MOFs and dyes, thus opening a new perspective for the development of white light emitting materials. A strategy by encapsulating organic dyes into the pores of a luminescent metal‐organic framework is developed to achieve white‐light‐emitting phosphor. The resulting composite ZJU‐28⊃DSM/AF (0.02 wt% DSM, 0.06 wt% AF) exhibits a broadband white emission with ideal CIE coordinates of (0.34, 0.32), high CRI value of 91, and moderate CCT value of 5327 K.
      PubDate: 2015-07-03T06:09:02.720908-05:
      DOI: 10.1002/adfm.201501756
       
  • Synthetic Crystals of Silver with Carbon: 3D Epitaxy of Carbon
           Nanostructures in the Silver Lattice
    • Authors: Lourdes G. Salamanca‐Riba; Romaine A. Isaacs, Melburne C. LeMieux, Jiayu Wan, Karen Gaskell, Yeping Jiang, Manfred Wuttig, Azzam N. Mansour, Sergey N. Rashkeev, Maija M. Kuklja, Peter Y. Zavalij, Jaime R. Santiago, Liangbing Hu
      Abstract: Only minimum amounts of carbon can be incorporated into silver, gold, and copper in a thermodynamically stable form. Here, the structure of stable silver carbon alloys is described, which are produced by thermoelectrically charging molten silver with carbon ions. Transmission electron microscopy and Raman scattering are combined to establish that large amount of carbon is accommodated in the form of epitaxial graphene‐like sheets. The carbon bonds covalently to the silver matrix as predicted from density functional theory (DFT) calculations with bond energies in the range 1.1–2.2 eV per atom or vacancy. Graphitic‐like sheets embedded in the crystal lattice of silver form 3D epitaxial structures with the host metal with a strain of ≈13% compared to equilibrium graphene. The carbon nanostructures persist upon remelting and resolidification. A DFT‐based analysis of the phonon density of states confirms the presence of intense vibration modes related to the AgC bonds observed in the Raman spectra of the alloy. The solid silver–high carbon alloy, termed “Ag‐covetic,” displays room temperature electrical conductivity of 5.62 × 107 S m−1 even for carbon concentrations of up to ≈6 wt% (36 at%). This process of incorporation of carbon presents a new paradigm for electrocharging assisted bulk processing. Incorporation of C in the lattice of silver is produced by electrocharging assisted bulk processing to create a synthetic alloy called silver covetic. In some regions the carbon forms layers of graphene intercalated between the atomic planes of silver forming a 3D nanoepitaxial structure. Carbon and silver atoms bond at carbon vacancies and edges of graphene‐like sheets or ribbons.
      PubDate: 2015-07-02T12:28:14.209677-05:
      DOI: 10.1002/adfm.201501156
       
  • Alcohol as a Processing Solvent of Polymeric Semiconductors to Fabricate
           Environmentally Benign and High Performance Polymer Field Effect
           Transistors
    • Authors: Kwang Hee Cheon; Hyungju Ahn, Jangwhan Cho, Hui‐Jun Yun, Byung Tack Lim, Dong Jin Yun, Han‐Koo Lee, Soon‐Ki Kwon, Yun‐Hi Kim, Dae Sung Chung
      Abstract: Here, a novel strategy is reported to develop polymer field effect transistors using ethanol, propanol, and butanol—the most environmentally benign solvent except water—as processing solvents. From such environmentally benign processes, for the first time high‐mobility (>1 cm2 V−1 s−1) polymer field effect transistors are demonstrated. These mobility values realized from “really green solvents” exceed those of conventional hydrogenated amorphous silicon semiconductors. To achieve this 1) stable sub‐microparticles of conjugated polymers dispersed in alcohols are fabricated, 2) an aldehyde‐assisted surface tension‐depression methodology is developed to successfully form thin films from alcohol, and 3) the structural information of alcohol‐dispersed sub‐microparticles of semiconducting polymers is carefully characterized. Colloidal solutions of conjugated semiconducting polymer are fabricated using a simple dispersion method of conjugated random copolymer in low‐molecular‐weight alcohols, including ethanol, propanol, and butanol. From such environmentally benign processes, for the first time, high‐mobility (>1 cm2 V−1 s−1) polymer field effect transistors are demonstrated.
      PubDate: 2015-07-02T12:27:39.054559-05:
      DOI: 10.1002/adfm.201500877
       
  • Fragile‐to‐Strong Crossover in Supercooled Liquid
           Ag‐In‐Sb‐Te Studied by Ultrafast Calorimetry
    • Authors: Jiri Orava; Daniel W. Hewak, A. Lindsay Greer
      Abstract: Phase‐change random‐access memory relies on the reversible crystalline‐glassy phase change in chalcogenide thin films. In this application, the speed of crystallization is critical for device performance: there is a need to combine ultrafast crystallization for switching at high temperature with high resistance to crystallization for non‐volatile data retention near to room temperature. In phase‐change media such as nucleation‐dominated Ge2Sb2Te5, these conflicting requirements are met through the highly “fragile” nature of the temperature dependence of the viscosity of the supercooled liquid. The present study explores, using ultrafast‐heating calorimetry, the equivalent temperature dependence for the growth‐dominated medium Ag‐In‐Sb‐Te. The crystallization shows (unexpectedly) Arrhenius temperature dependence over a wide intermediate temperature range. Here it is shown that this is evidence for a fragile‐to‐strong crossover on cooling the liquid. Such a crossover has many consequences for the interpretation and control of phase‐change kinetics in chalcogenide media, helping to understand the distinction between nucleation‐ and growth‐dominated crystallization, and offering a route to designing improved device performance. The temperature‐dependent viscosity inferred for liquid Ag‐In‐Sb‐Te (AIST) presents evidence for a fragile‐to‐strong crossover on cooling the liquid. Such a crossover is relevant for the application of AIST and other chalcogenides, helping to understand the distinction between nucleation‐ and growth‐dominated crystallization, and guiding materials design to combine fast switching and non‐volatility for application in phase‐change memory and neuromorphic computing.
      PubDate: 2015-07-02T12:26:41.468261-05:
      DOI: 10.1002/adfm.201501607
       
  • Mechanistic Studies of Transition Metal‐Terephthalate Coordination
           Complexes upon Electrochemical Lithiation and Delithiation
    • Authors: Hyun Ho Lee; Yuwon Park, Su Hwan Kim, Sun‐Hwa Yeon, Sang Kyu Kwak, Kyu Tae Lee, Sung You Hong
      Abstract: Redox‐active organic molecules are intriguing candidates as active electrode materials for next‐generation rechargeable batteries due to their structural diversity, environmental friendliness, and solution‐phase preparation processes. Recently, a transition metal–organic coordination approach is exploited to construct high capacity anodes for lithium‐ion rechargeable batteries. Here, a family of transition metal–organic coordination complexes with terephthalate ligands is synthesized that exhibit reversible capacities above 1100 mA h g−1. The reaction mechanism to describe the multi‐electron redox processes is investigated at the molecular‐level via the synchrotron‐sourced X‐ray absorption spectroscopy and solid‐state NMR analyses. The spectroscopic studies reveal that the electrochemical process involves oxidation state changes of the transition metals followed by additional lithium insertion/extraction in the conjugated aromatic ligands. The combined approaches assisted by synthetic organic chemistry and solid‐state analysis provide mechanistic insights into excessive lithiation processes that have implications for the design of high‐performance anode materials. The multi‐electron redox mechanism of transition metal terephthalates upon electrochemical lithiation and delithiation is investigated via synchrotron‐sourced X‐ray absorption spectroscopy and solid state 13C NMR analysis.
      PubDate: 2015-07-02T06:24:42.415338-05:
      DOI: 10.1002/adfm.201501436
       
  • High‐Performance Planar Solar Cells Based On CH3NH3PbI3‐xClx
           Perovskites with Determined Chlorine Mole Fraction
    • Authors: Yunlong Li; Weihai Sun, Weibo Yan, Senyun Ye, Haitao Peng, Zhiwei Liu, Zuqiang Bian, Chunhui Huang
      Abstract: Solution‐processable hybrid perovskite solar cells are a new member of next generation photovoltaics. In the present work, a low‐temperature two‐step dipping method is proposed for the fabrication of CH3NH3PbI3‐xClx perovskite films on the indium tin oxide glass/poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) substrate. The bandgaps of the CH3NH3PbI3‐xClx perovskite films are tuned in the range between 1.54 and 1.59 eV by adjusting the PbCl2 mole fraction (nCl/(nCl + nI)) in the initial mixed precursor solution from 0.10 to 0.40. The maximum chlorine mole fraction measured by a unique potentiometric titration method in the produced CH3NH3PbI3‐xClx films can be up to 0.220 ± 0.020 (x = 0.660 ± 0.060), which is much higher than that produced by a one‐step spin‐coating method (0.056 ± 0.015, x = 0.17 ± 0.04). The corresponding solar cell with the CH3NH3PbI2.34±0.06Cl0.66±0.06 perovskite film sandwiched between PEDOT:PSS and C60 layers exhibits a power conversion efficiency as high as 14.5%. Meanwhile, the open‐circuit potential (Voc) of the device reaches 1.11 V, which is the highest Voc reported in the perovskite solar cells fabricated on PEDOT:PSS so far. A unique potentiometric titration method is used to measure the chlorine content of CH3NH3I3‐xClx perovskites. The maximum chlorine mole fraction of CH3NH3I3‐xClx fabricated by low‐temperature two‐step dipping method can be up to 0.220 ± 0.020 and the corresponding inverted solar cell shows 14.5% efficiency with a high Voc of 1.11 V.
      PubDate: 2015-07-02T06:24:11.870919-05:
      DOI: 10.1002/adfm.201501289
       
  • Enhanced Performance of Organic Solar Cells with Increased End Group
           Dipole Moment in Indacenodithieno[3,2‐b]thiophene‐Based
           Molecules
    • Authors: Jeremy J. Intemann; Kai Yao, Feizhi Ding, Yunxiang Xu, Xukai Xin, Xiaosong Li, Alex K.‐Y. Jen
      Abstract: Four new molecular donors are reported using a D1‐A‐D2‐A‐D1 structure, where D1 is an oligiothiophene, A is a benzothiadiazole, and D2 is indacenodithieno[3,2‐b]thiophene. The resulting materials provide efficiencies as high as 6.5% in organic solar cells, without the use of solvent additives or thermal/solvent annealing. A strong correlation between the end group (D1‐A) dipole moment and the fill factor (FF), mobility, and loss in the open‐circuit voltage (VOC) is observed. Indacenodithieno[3,2‐b]thiophene‐fluorobenzothiadiazole‐terthiophene (IDTT‐FBT‐3T) possesses the largest end group dipole moment, and in turn, has the highest mobility, FF, and power conversion efficiency in devices. It also has a similarly high VOC (0.95 V) to the other materials (0.93–0.99 V), despite possessing a much higher highest occupied molecular orbital (HOMO) energy level. Four new ladder‐type molecular donors are reported with varying end groups and their photovoltaic properties are explored. It is found that utilizing end groups with larger ground‐state dipole moments results in significantly enhanced fill factors and decreased voltage losses in devices.
      PubDate: 2015-07-02T06:23:32.612362-05:
      DOI: 10.1002/adfm.201501600
       
  • Hard Radiation Detection from the Selenophosphate Pb2P2Se6
    • Authors: Peng L. Wang; Zhifu Liu, Pice Chen, John A. Peters, Gangjian Tan, Jino Im, Wenwen Lin, Arthur J. Freeman, Bruce W. Wessels, Mercouri G. Kanatzidis
      Abstract: The heavy metal selenophosphate, Pb2P2Se6, is a promising new material for cost‐effective X‐ray/γ‐ray detection. Crystal boules of Pb2P2Se6 up to 25 mm in length and 15 mm in diameter are grown by a vertical Bridgman method. They are cut and processed into size‐appropriate wafers for physical, photo‐transport property studies, as well as γ‐ray detector testing. The material is a semiconductor with an indirect bandgap of 1.88 eV and has electrical resistivity in the range of 1 × 1010 Ω cm. Pb2P2Se6 single crystal samples display a significant photoconductivity response to optical, X‐ray, and γ‐ray radiation. When tested with a 57Co γ‐ray source, Pb2P2Se6 crystals show spectroscopic response and several generated pulse height spectra resolving the 122.1 and 136.5 keV 57Co radiation. The mobility–lifetime product of Pb2P2Se6 is estimated to be ≈3.5 × 10−5 cm2 V−1 for electron carriers. The Pb2P2Se6 compound melts congruently at 812 °C and has robust chemical/physical properties that promise low cost bulk production and detector development. Wide bandgap selenophosphate Pb2P2Se6 is identified as a cost‐effective X‐ray and γ‐ray detector material. The crystal growth of Pb2P2Se6 and characterizations in terms of its optical, electrical, thermal, and mechanical properties are reported. A Pb2P2Se6 single crystal detector is able to resolve 57Co radiation.
      PubDate: 2015-07-02T06:23:25.59544-05:0
      DOI: 10.1002/adfm.201501826
       
  • A Highly Elastic and Rapidly Crosslinkable Elastin‐Like
           Polypeptide‐Based Hydrogel for Biomedical Applications
    • Authors: Yi‐Nan Zhang; Reginald K. Avery, Queralt Vallmajo‐Martin, Alexander Assmann, Andrea Vegh, Adnan Memic, Bradley D. Olsen, Nasim Annabi, Ali Khademhosseini
      Abstract: Elastin‐like polypeptides (ELPs) are promising for biomedical applications due to their unique thermoresponsive and elastic properties. ELP‐based hydrogels have been produced through chemical and enzymatic crosslinking or photocrosslinking of modified ELPs. Herein, a photocrosslinked ELP gel using only canonical amino acids is presented. The inclusion of thiols from a pair of cysteine residues in the ELP sequence allows disulfide bond formation upon exposure to UV light, leading to the formation of a highly elastic hydrogel. The physical properties of the resulting hydrogel such as mechanical properties and swelling behavior can be easily tuned by controlling ELP concentrations. The biocompatibility of the engineered ELP hydrogels is shown in vitro as well as corroborated in vivo with subcutaneous implantation of hydrogels in rats. ELP constructs demonstrate long‐term structural stability in vivo, and early and progressive host integration with no immune response, suggesting their potential for supporting wound repair. Ultimately, functionalized ELPs demonstrate the ability to function as an in vivo hemostatic material over bleeding wounds. Photocrosslinkable elastin‐like polypeptides (ELPs) are demonstrated to be potential biomedical constructs. ELPs with only canonical amino acids are crosslinked with the addition of photoinitiator, resulting in tunable modulus and tensile strength based upon the ELP concentration. In vitro and in vivo biocompatibility, in addition to their extensibility, make these ELPs candidates for sealants and hemostats among other biomedical applications requiring extensible substrates.
      PubDate: 2015-07-01T23:10:02.894996-05:
      DOI: 10.1002/adfm.201501489
       
  • Beyond State of the Art Honeycomb Membranes: High Performance Ordered
           Arrays from Multiprogrammable Linear‐Dendritic Block Copolymers
    • Authors: Surinthra Mongkhontreerat; Marie V. Walter, Oliver C. J. Andrén, Yanling Cai, Michael Malkoch
      Abstract: A new generation of honeycomb membranes is herein described from a novel library of multipurpose linear‐dendritic block copolymers. These are accomplished by combining atom transfer radical polymerization together with dendrimer chemistry and click reactions. The resulted amorphous block copolymers, with Tg between 30 and 40 °C, display three important functions, i.e., pore generating aromatic groups, crosslinking azides, and multiple dendritic functional groups. All block copolymers enable the successful fabrication of honeycomb membranes through the facile breath figure method. The peripheral dendritic functionality is found to influence the porous morphologies from closed pored structure with pore size of 1.12 μm2 to open pore structure with pore size 10.26 μm2. Facile UV crosslinking of the azides yields membranes with highly durable structural integrity. Upon crosslinking, the pH and thermal stability are extended beyond the noncrosslinked membranes in which the porous integrity is maintained up to 400 °C and pH 1–14. Taking into account the straightforward and cost‐efficient strategy to generate ordered, functional, and structurally stable honeycomb membranes on various solid substrates, it is apparent that these multipurpose block copolymers may unlock future applications including use as molds for soft lithography. A new generation of high performance honeycomb membranes is presented from multiprogrammable block copolymers. Facile crosslinking results in functional membranes that are noticed to withstand temperatures up to 400 °C and pH from 1–14. These state‐of‐art honeycomb membranes are found to be excellent cell repellent surfaces and are exploited as masters for soft lithographical applications.
      PubDate: 2015-07-01T12:58:46.684697-05:
      DOI: 10.1002/adfm.201501643
       
  • New Dielectric Elastomers with Variable Moduli
    • Authors: Wei Hu; Zhi Ren, Junpeng Li, Erin Askounis, Zhixin Xie, Qibing Pei
      Abstract: Dielectric elastomers have been widely investigated for muscle‐like soft actuators and capacitive sensors. Mechanical properties play a central role in the performances of the active material. Most elastomers have specific moduli pre‐determined by the polymers' molecular structures, which are not suitable for applications in changing working conditions as natural muscles are capable of. Here new dielectric elastomers are described exhibiting variable moduli controlled via thermal treatment. The elastomers contain furan‐maleimide Diels–Alder adduct moieties to administer the crosslinking densities of the elastomeric networks via reversible Diels–Alder/retro‐Diels–Alder cycloaddition reaction, resulting in changes in the elastomers' moduli. One of the synthesized elastomers has moduli that can be controlled between 0.17 and 0.52 MPa incrementally and reversibly. Capacitive strain sensors based on this elastomer can be operated in both rigid and soft modes to achieve variable sensing response up to 30% linear strain. Actuators were fabricated and operated in both high strain mode (35% actuation area strain at 65 MV m−1) and high force output mode (0.55 MPa at 104 MV m−1). The elastomers can exhibit a range of stress–strain outputs in similar fashion as muscle. New dielectric elastomers exhibiting variable moduli are presented. The elastomers contain furan‐maleimide Diels–Alder adduct moieties to administer the crosslinking densities, resulting in changes in the elastomers' moduli. Capacitive strain sensors based on this elastomer can be operated in both rigid and soft modes. Actuators are fabricated and operated in both high strain and high force output modes.
      PubDate: 2015-07-01T12:58:32.955123-05:
      DOI: 10.1002/adfm.201501530
       
  • Photophysics of Molecular‐Weight‐Induced Losses in
           Indacenodithienothiophene‐Based Solar Cells
    • Authors: Nicola Gasparini; Athanasios Katsouras, Mamantos I. Prodromidis, Apostolos Avgeropoulos, Derya Baran, Michael Salvador, Stefanie Fladischer, Erdmann Spiecker, Christos L. Chochos, Tayebeh Ameri, Christoph J. Brabec
      Abstract: The photovoltaic performance and optoelectronic properties of a donor–acceptor copolymer are reported based on indacenodithienothiophene (IDTT) and 2,3‐bis(3‐(octyloxy)phenyl)quinoxaline moieties (PIDTTQ) as a function of the number‐average molecular weight (Mn). Current–voltage measurements and photoinduced charge carrier extraction by linear increasing voltage (photo‐CELIV) reveal improved charge generation and charge transport properties in these high band gap systems with increasing Mn, while polymers with low molecular weight suffer from diminished charge carrier extraction because of low mobility–lifetime (μτ) product. By combining Fourier‐transform photocurrent spectroscopy (FTPS) with electroluminscence spectroscopy, it is demonstrate that increasing Mn reduces the nonradiative recombination losses. Solar cells based on PIDTTQ with Mn = 58 kD feature a power conversion efficiency of 6.0% and a charge carrier mobility of 2.1 × 10−4 cm2 V−1 s−1 when doctor bladed in air, without the need for thermal treatment. This study exhibits the strong correlations between polymer fractionation and its optoelectronics characteristics, which informs the polymer design rules toward highly efficient organic solar cells. The synthesis of a series of indaceno­dithieno[3,2‐b]thiophenebased donor–acceptor copolymers (PIDTT) and the strong correlations between polymer fractionation and its optoelectronics characteristics are demonstrated. In the best case, the active material exhibits more than 6% PCE in inverted solar cells processed via doctor blading in air, without requiring thermal treatment.
      PubDate: 2015-06-26T09:32:52.629338-05:
      DOI: 10.1002/adfm.201501062
       
  • Doxorubicin‐Loaded Single Wall Nanotube Thermo‐Sensitive
           Hydrogel for Gastric Cancer Chemo‐Photothermal Therapy
    • Authors: Minyu Zhou; Shuhan Liu, Yaqi Jiang, Huanrong Ma, Min Shi, Quanshi Wang, Wen Zhong, Wangjun Liao, Malcolm M. Q. Xing
      Abstract: Single wall carbon nanotube (SWNT) based thermo‐sensitive hydrogel (SWNT‐GEL) is reported, which provides an injectable drug delivery system as well as a medium for photothermal transduction. SWNT‐hydrogel alone appears to be nontoxic on gastric cancer cells (BGC‐823 cell line) but leads to cell death with NIR radiation through a hyperthermia proapoptosis mechanism. By incorporating hyperthermia therapy and controlled in situ doxorubicin (DOX) release, DOX‐loaded SWNT‐hydrogel with NIR radiation proves higher tumor suppression rate on mice xenograft gastric tumor models compared to free DOX without detectable organ toxicity. The developed system demonstrates improved efficacy of chemotherapeutic drugs which overcomes systemic adverse reactions and presents immense potential for gastric cancer treatment. A DOX‐loaded SWNT‐based thermo‐sensitive hydrogel (DOX/SWNT‐GEL) in situ drug delivery system is reported. DOX/SWNT‐GEL exhibits pro‐apoptosis effect through a hyperthermia therapy mechanism by NIR radiation, as well as better tumor growth suppression efficacy compared with free DOX in vivo. The combination of controlled drug release and photothermal transduction of DOX/SWNT‐GEL provides a promising prospect in future nanomedicine progress.
      PubDate: 2015-06-26T09:29:42.021844-05:
      DOI: 10.1002/adfm.201501434
       
  • Poly(Acrylic Acid) Modification of Nd3+‐Sensitized Upconversion
           Nanophosphors for Highly Efficient UCL Imaging and pH‐Responsive
           Drug Delivery
    • Authors: Bei Liu; Yinyin Chen, Chunxia Li, Fei He, Zhiyao Hou, Shanshan Huang, Haomiao Zhu, Xueyuan Chen, Jun Lin
      Abstract: In this work, a simple method is demonstrated for the synthesis of multifunctional core–shell nanoparticles NaYF4:Yb,Er@NaYF4:Yb@NaNdF4:Yb@NaYF4:Yb@PAA (labeled as Er@Y@Nd@Y@PAA or UCNP@PAA), which contain a highly effective 808‐nm‐to‐visible UCNP core and a thin shell of poly(acrylic acid) (PAA) to achieve upconversion bioimaging and pH‐sensitive anticancer chemotherapy simultaneously. The core–shell Nd3+‐sensitized UCNPs are optimized by varying the shell number, core size, and host lattices. The final optimized Er@Y@Nd@Y nanoparticle composition shows a significantly improved upconversion luminescence intensity, that is, 12.8 times higher than Er@Y@Nd nanoparticles. After coating the nanocomposites with a thin layer of PAA, the resulting UCNP@PAA nanocomposite perform well as a pH‐responsive nanocarrier and show clear advantages over UCNP@mSiO2, which are evidenced by in vitro/in vivo experiments. Histological analysis also reveals that no pathological changes or inflammatory responses occur in the heart, lungs, kidneys, liver, and spleen. In summary, this study presents a major step forward towards a new therapeutic and diagnostic treatment of tumors by using 808‐nm excited UCNPs to replace the traditional 980‐nm excitation. Multifunctional uniform core–shell nanoparticles NaYF4:Yb, Er@NaYF4:Yb@NaNdF4:Yb@NaYF4:Yb@PAA (UCNP@PAA) consist of a highly effective 808‐nm‐to‐visible UCNP core (with an absolute upconversion quantum yield of 0.18% in green emission mode) and a thin shell of PAA. These UCNP@PAA nanoparticles are designed and synthesized to simultaneously achieve in vitro/in vivo upconversion bioimaging and pH‐sensitive chemotherapy.
      PubDate: 2015-06-25T06:31:22.312389-05:
      DOI: 10.1002/adfm.201501582
       
  • On the Mechanism of Cuprate Crystal Growth: The Role of Mixed Metal
           Carbonates
    • Authors: David C. Green; Rebecca Boston, Stefan Glatzel, Martin R. Lees, Stuart C. Wimbush, Jason Potticary, Wataru Ogasawara, Simon R. Hall
      Abstract: The mechanism of formation of the superconductor Bi2Sr2CaCu2O8+x (Bi‐2212) has been an open question since its discovery in 1988. By controlling crystal growth through the use of biopolymers as multivalent cation chelating agents, it is demonstrated through X‐ray diffraction and thermogravimetric analysis, that it is the formation of a mixed metal carbonate eutectic that promotes the formation of the target phase. X‐ray diffraction experiments, supported by infrared spectroscopy, identify this phase as (Sr1−x Ca x )CO3. This knowledge allows to further reduce the eutectic melting point by the incorporation of a biopolymer rich in potassium ions, resulting in the scalable formation of Bi‐2212 at a temperature 50 °C lower than has been achieved previously. The precise mechanism of formation of the superconductor Bi2Sr2CaCu2O8 +x (Bi‐2212) is unknown. Here, via extensive X‐ray diffraction, infrared spectroscopy, and thermogravimetric analysis, the mechanism is identified, and it is found that a carbonate eutectic (Sr1−x Ca x )CO3 is the key driver in the formation of Bi‐2212. The introduction of potassium ions leads to the formation of Bi‐2212 at a temperature 50 °C lower than has been achieved previously.
      PubDate: 2015-06-25T06:30:20.604189-05:
      DOI: 10.1002/adfm.201501058
       
  • Optimizing the Size of Micellar Nanoparticles for Efficient siRNA Delivery
    • Authors: Shi Liang; Xian‐Zhu Yang, Xiao‐Jiao Du, Hong‐Xia Wang, Hong‐Jun Li, Wei‐Wei Liu, Yan‐Dan Yao, Yan‐Hua Zhu, Yin‐Chu Ma, Jun Wang, Er‐Wei Song
      Abstract: Delivery of small interfering RNA (siRNA) by nanocarriers has shown promising therapeutic potential in cancer therapy. However, poor understanding of the correlation between the physicochemical properties of nanocarriers and their interactions with biological systems has significantly hindered its anticancer efficacy. Herein, in order to identify the optimal size of nanocarriers for siRNA delivery, different sized cationic micellar nanoparticles (MNPs) (40, 90, 130, and 180 nm) are developed that exhibit similar siRNA binding efficacies, shapes, surface charges, and surface chemistries (PEGylation) to ensure size is the only variable. Size‐dependent biological effects are carefully and comprehensively evaluated through both in vitro and in vivo experiments. Among these nanocarriers, the 90 nm MNPs show the optimal balance of prolonged circulation and cellular uptake by tumor cells, which result in the highest retention in tumor cells. In contrast, larger MNPs are rapidly cleared from the circulation and smaller MNPs are inefficiently taken up by tumor cells. Accordingly, 90 nm MNPs carrying polo‐like kinase 1 (Plk1)‐specific siRNA (siPlk1) show superior antitumor efficacy, indicating that 90 nm could either be the optimal size for systemic delivery of siRNA or close to it. Our findings provide valuable information for rationally designing nanocarriers for siRNA‐based cancer therapy in the future. To investigate the optimal size of nanocarriers for siRNA delivery, different sized MNP/siRNAs are rationally designed. Size‐dependent biological effects on circulation, internalization, retention, and overall antitumor efficacy are carefully and comprehensively evaluated. These results indicate that 90 nm could be at or close to the optimal size for systemic delivery of siRNA.
      PubDate: 2015-06-25T06:29:58.260844-05:
      DOI: 10.1002/adfm.201501548
       
  • Restoring Intrinsic Properties of Electromagnetic Radiators Using
           Ultralightweight Integrated Metasurface Cloaks
    • Authors: Zhi Hao Jiang; Peter E. Sieber, Lei Kang, Douglas H. Werner
      Abstract: The concept of invisibility has garnered long‐standing interest throughout human history but has only been realized experimentally within the past decade, albeit over a limited bandwidth. While the physical wave phenomenon of a reduced scattering signature has been demonstrated with different cloaking methods such as transformation optics and scattering cancellation, such technology has yet to be incorporated into any practical real‐world devices. Through the use of quasi‐2D functional metasurfaces, the long‐standing issue of simultaneous mutual coupling and radiation blockage is addressed that occurs when two or more electromagnetic radiators are placed in close proximity to one another. The proposed compact and ultralightweight metasurfaces, comprising arrays of subwavelength electric and magnetic resonators with tailored dispersive properties, are capable of fully restoring the intrinsic properties of real‐world electromagnetic radiators when placed in a multiradiator environment. This work introduces a general design approach to bridge the gap between the theory and practice for cloaks, which is applicable to microwave, terahertz, and optical radiators, as well as acoustic and thermal sources. Moreover, this technology provides an unprecedented opportunity for enabling high‐density deployment of radiating systems with low interference and undistorted signal wave fronts. Integrated ultralightweight metasurface cloaking coatings are demonstrated for restoring intrinsic properties of electromagnetic radiators. By tailoring the dispersive properties of the metasurfaces, the mutual coupling and mutual blockage between multiple radiators can be simultaneously reduced. The general concept and design approach pave the way for dense deployment of terahertz/optical antennas as well as radiators in other realms of physics.
      PubDate: 2015-06-25T06:29:30.443181-05:
      DOI: 10.1002/adfm.201501261
       
  • Strongly Anisotropic Thermal Conductivity of Free‐Standing Reduced
           Graphene Oxide Films Annealed at High Temperature
    • Authors: Jackie D. Renteria; Sylvester Ramirez, Hoda Malekpour, Beatriz Alonso, Alba Centeno, Amaia Zurutuza, Alexandr I. Cocemasov, Denis L. Nika, Alexander A. Balandin
      Abstract: Thermal conductivity of free‐standing reduced graphene oxide films subjected to a high‐temperature treatment of up to 1000 °C is investigated. It is found that the high‐temperature annealing dramatically increases the in‐plane thermal conductivity, K, of the films from ≈3 to ≈61 W m−1 K−1 at room temperature. The cross‐plane thermal conductivity, K⊥, reveals an interesting opposite trend of decreasing to a very small value of ≈0.09 W m−1 K−1 in the reduced graphene oxide films annealed at 1000 °C. The obtained films demonstrate an exceptionally strong anisotropy of the thermal conductivity, K/K⊥ ≈ 675, which is substantially larger even than in the high‐quality graphite. The electrical resistivity of the annealed films reduces to 1–19 Ω □−1. The observed modifications of the in‐plane and cross‐plane thermal conductivity components resulting in an unusual K/K⊥ anisotropy are explained theoretically. The theoretical analysis suggests that K can reach as high as ≈500 W m−1 K−1 with the increase in the sp2 domain size and further reduction of the oxygen content. The strongly anisotropic heat conduction properties of these films can be useful for applications in thermal management. The high‐temperature treatment of reduced graphene oxide films dramatically increases their in‐plane thermal conductivity at room temperature. The cross‐plane thermal conductivity reveals an opposite trend of decreasing to a very small value in the films annealed at 1000 °C. The synthesized films demonstrate an exceptionally strong anisotropy of thermal conductivity, which is useful for thermal management applications.
      PubDate: 2015-06-25T06:28:57.545098-05:
      DOI: 10.1002/adfm.201501429
       
  • Electrochemically Nanostructured Polyvinylferrocene/Polypyrrole Hybrids
           with Synergy for Energy Storage
    • Authors: Wenda Tian; Xianwen Mao, Paul Brown, Gregory C. Rutledge, T. Alan Hatton
      Abstract: Unconjugated redox polymers, such as polyvinylferrocene (PVF), have rarely been used for energy storage due to their low intrinsic conductivity. Conducting polymers with conjugated backbones, though conductive, may suffer from insufficient exposure to the electrolyte due to the often formed nonporous structures. The present work overcomes this limitation via simultaneous electropolymerization of pyrrole and electroprecipitation of PVF on electrode surfaces. This synthesis method relies on the π–π stacking interactions between the aromatic pyrrole monomers and the metallocene moieties of PVF. This fabrication process results in a highly porous polymer film, which enhances the ion accessibility to polypyrrole (PPy). PPy serves as a “molecular wire,” improving the electronic conductivity of the hybrid and the utilization efficiency of ferrocene. The PVF/PPy hybrid exhibited a specific capacitance of 514.1 F g−1 , which significantly exceeds those of PPy (27.3 F g−1) and PVF (79.0 F g−1), respectively. This approach offers an alternative to nanocarbon materials for improving the electronic conductivity of polymer hybrids, and suggests a new strategy for fabricating nanostructured polymer hybrids. This strategy can potentially be applied to various polymers with π‐conjugated backbones and redox polymers with metallocene moieties for applications such as energy storage, sensing, and catalysis. The π–π stacking interactions between aromatic monomers and metallocene moieties are exploited via simultaneous electroprecipitation of polyvinylferrocene and electropolymerization of pyrrole to form a highly porous redox‐responsive hybrid. The resulting synergistic enhancement of the utilization efficiency of ferrocene and the accessibility of ions to polypyrrole leads to the significantly improved electrochemical energy storage performance.
      PubDate: 2015-06-24T13:24:38.634809-05:
      DOI: 10.1002/adfm.201501041
       
  • Tunable Photodynamic Switching of DArE@PAF‐1 for Carbon Capture
    • Authors: Richelle Lyndon; Kristina Konstas, Richard A. Evans, Daniel J. Keddie, Matthew R. Hill, Bradley P. Ladewig
      Abstract: A new type of photodynamic carbon capture material with up to 26 wt% CO2 desorption capacity is synthesized via incorporation of diarylethene (DArE) as guest molecules in porous aromatic framework‐1 (PAF‐1). In these host–guest complexes, the carboxylic acid groups featured in DArE allow multiple noncovalent interactions to exist. DArE loadings ranging from 1 to 50 wt% are incorporated in PAF‐1 and the complexes characterized by UV–vis spectroscopy, FT‐IR spectroscopy, CO2, and N2 adsorption. Successful inclusion of DArE in PAF‐1 is indicated by the reduction of pore size distributions and an optimum loading of 5 wt% is determined by comparing the percentage photo­response and CO2 uptake capacity at 1 bar. Mechanistic studies suggest that photoswitching modulates the binding affinity between DArE and CO2 toward the host, triggering carbon capture and release. This is the first known example of photodynamic carbon capture and release in a PAF. Dynamic light‐activated carbon capture and release in porous aromatic framework‐1 (PAF‐1) is achieved by successfully loading diarylethene (DArE) as a guest molecule. Up to 26 wt% CO2 desorption capacity is possible with 50 wt% DArE loading. The observed photodynamicity is because of host–guest competition between DArE and CO2 inside the sterically hindered pores of PAF‐1.
      PubDate: 2015-06-22T12:31:38.615327-05:
      DOI: 10.1002/adfm.201502069
       
  • Flexible Electronics: 3D Micromolding of Arrayed Waveguide Gratings on
           Upconversion Luminescent Layers for Flexible Transparent Displays without
           Mirrors, Electrodes, and Electric Circuits (Adv. Funct. Mater. 28/2015)
    • Authors: Satoshi Watanabe; Takeo Asanuma, Takafumi Sasahara, Hiroshi Hyodo, Mutsuyoshi Matsumoto, Kohei Soga
      Pages: 4369 - 4369
      Abstract: On page 4390, S. Watanabe, K. Soga, and co‐workers fabricate flexible upconversion transparent displays by constructing arrayed waveguide gratings on upconversion luminescent layers consisting of rare‐earth‐ion‐doped nano‐particles excited with near‐infrared laser beams at 850 nm and 1500 nm, which leads to two dimensional imaging on passive matrix mode without mirrors, transparent electrodes, and electric circuits in display monitors.
      PubDate: 2015-07-21T06:19:16.308109-05:
      DOI: 10.1002/adfm.201570189
       
  • Organic Electronics: Layered, Nanonetwork Composite Cathodes for Flexible,
           High‐Efficiency, Organic Light Emitting Devices (Adv. Funct. Mater.
           28/2015)
    • Authors: Junwei Xu; Gregory M. Smith, Chaochao Dun, Yue Cui, Jiwen Liu, Huihui Huang, Wenxiao Huang, David L. Carroll
      Pages: 4370 - 4370
      Abstract: Nanocomposite cathode structures with the aim of combining mechanical and electronic properties to achieve better performance in an organic flexible are examined by D. L. Carroll and team on page 4397. A flexible high‐efficiency alternating current (AC) driven field‐induced polymer electroluminescent) device is chosen as the platform system with the understanding that this approach to organic devices clearly points to organic light emitting diodes, organic thin‐film transistors, and other flexible systems.
      PubDate: 2015-07-21T06:19:18.219199-05:
      DOI: 10.1002/adfm.201570190
       
  • Contents: (Adv. Funct. Mater. 28/2015)
    • Pages: 4371 - 4378
      PubDate: 2015-07-21T06:19:18.075522-05:
      DOI: 10.1002/adfm.201570191
       
  • Protein Corona Influences Cell–Biomaterial Interactions in
           Nanostructured Tissue Engineering Scaffolds
    • Authors: Vahid Serpooshan; Morteza Mahmoudi, Mingming Zhao, Ke Wei, Senthilkumar Sivanesan, Khatereh Motamedchaboki, Andrey V. Malkovskiy, Andrew B. Goldstone, Jeffrey E. Cohen, Phillip C. Yang, Jayakumar Rajadas, Daniel Bernstein, Y. Joseph Woo, Pilar Ruiz‐Lozano
      Pages: 4379 - 4389
      Abstract: Biomaterials are extensively used to restore damaged tissues, in the forms of implants (e.g., tissue engineered scaffolds) or biomedical devices (e.g., pacemakers). Once in contact with the physiological environment, nanostructured biomaterials undergo modifications as a result of endogenous proteins binding to their surface. The formation of this macromolecular coating complex, known as “protein corona,” onto the surface of nanoparticles and its effect on cell–particle interactions are currently under intense investigation. In striking contrast, protein corona constructs within nanostructured porous tissue engineering scaffolds remain poorly characterized. As organismal systems are highly dynamic, it is conceivable that the formation of distinct protein corona on implanted scaffolds might itself modulate cell–extracellular matrix interactions. Here, it is reported that corona complexes formed onto the fibrils of engineered collagen scaffolds display specific, distinct, and reproducible compositions that are a signature of the tissue microenvironment as well as being indicative of the subject's health condition. Protein corona formed on collagen matrices modulated cellular secretome in a context‐specific manner ex vivo, demonstrating their role in regulating scaffold–cellular interactions. Together, these findings underscore the importance of custom‐designing personalized nanostructured biomaterials, according to the biological milieu and disease state. The use of protein corona as in situ biosensor of temporal and local biomarkers is proposed. The formation of “protein corona” complexes onto the nanofibrillar structure of tissue engineering collagen‐based scaffolds is evaluated. The corona decorations formed onto collagen matrices are tissue‐specific and subject's health‐specific, and regulated cellular secretome ex vivo. In sum, the results demonstrate the significance of protein corona formation onto tissue engineered constructs in the cell–biomaterial interactions.
      PubDate: 2015-06-05T10:26:17.547534-05:
      DOI: 10.1002/adfm.201500875
       
  • 3D Micromolding of Arrayed Waveguide Gratings on Upconversion Luminescent
           Layers for Flexible Transparent Displays without Mirrors, Electrodes, and
           Electric Circuits
    • Authors: Satoshi Watanabe; Takeo Asanuma, Takafumi Sasahara, Hiroshi Hyodo, Mutsuyoshi Matsumoto, Kohei Soga
      Pages: 4390 - 4396
      Abstract: A new technique for the fabrication of arrayed waveguide gratings on upconversion luminescent layers for flexible transparent displays is reported. Ho3+‐ and Yb3+‐codoped NaYF4 nanoparticles are synthesized by hydrothermal techniques. Transparent films consisting of two transparent polymers on the NaYF4 nanoparticle films exhibit mechanical flexibility and high transparence in visible region. Patterned NaYF4 nanoparticle films are fabricated by calcination‐free micromolding in capillaries. Arrayed waveguide gratings consisting of the two transparent polymers are formed on the patterned NaYF4 nanoparticle films by micromolding in capillaries. Green and red luminescence is observed from the upconversion luminescent layers of the NaYF4 nanoparticle films in the arrayed waveguide gratings under excitation at 980 nm laser light. Arrayed waveguide gratings on the upconversion luminescent layers are fabricated with Er3+‐doped NaYF4 nanoparticles which can convert two photons at 850 and 1500 nm into single photon at 550 nm. These results demonstrate that flexible transparent displays can be fabricated by constructing arrayed waveguide gratings on upconversion luminescent layers, which can operate in nonprojection mode without mirrors, transparent electrodes, and electric circuits. Arrayed waveguide gratings consisting of two optical polymers are fabricated on patterned upconversion luminescent layers prepared with rare‐earth‐ion‐doped nanoparticle films for upconversion transparent displays. These displays take advantage of long‐operating lifetimes, high transparency, and mechanical flexibility, and do not require mirrors, transparent electrodes, transistor circuits, leading to the fabrication with low cost, minimized material consumptions, and few fabrication steps.
      PubDate: 2015-06-05T02:21:18.210414-05:
      DOI: 10.1002/adfm.201500542
       
  • Layered, Nanonetwork Composite Cathodes for Flexible,
           High‐Efficiency, Organic Light Emitting Devices
    • Authors: Junwei Xu; Gregory M. Smith, Chaochao Dun, Yue Cui, Jiwen Liu, Huihui Huang, Wenxiao Huang, David L. Carroll
      Pages: 4397 - 4404
      Abstract: In this work, the application of an aluminum (Al)/multiwall carbon nanotube (MWCNT)/Al, multilayered electrode to flexible, high‐efficiency, alternating current driven organic electroluminescent devices (AC‐OEL), is reported. The electrode is fabricated by sandwiching a spray‐cast nanonetwork film of MWCNTs between two evaporated layers of Al. The resulting composite film facilitates a uniform charge distribution across a robust crack‐free electrode under various bending angles. It is demonstrated that these composite electrodes stabilize the power efficiency of flexible devices for bending angles up to 120°, with AC‐OEL device power efficiencies of ≈22 lm W−1 at luminances of ≈4000 cd m−2 (using no output coupling). Microscopic examination of the Al/MWCNTs/Al electrode after bending of up to 1300 cycles suggests that the nanotubes significantly enhance the mechanical properties of the thin Al layers while providing a moderate modification to the work function of the metal. While the realization of robust, high‐brightness, and high‐efficiency AC‐OEL devices is potentially important in their future lighting applications, it is anticipated that this to also have significant impact in standard organic light emitting diodes lighting applications. Nanocomposite cathode structures—in this case metals together with multiwalled nanotubes—with the aim of combining mechanical and electronic properties to achieve better performance in an organic flexible are examined. A flexible high‐efficiency alternating current (AC) driven field‐induced polymer electroluminescent) device is chosen as the platform system with the understanding that this approach to organic devices clearly points to organic light emitting diodes, organic thin‐film transistors, and other flexible systems.
      PubDate: 2015-06-10T22:57:28.075176-05:
      DOI: 10.1002/adfm.201501068
       
  • Graphene‐Oxide‐Conjugated Polymer Hybrid Materials for
           Calmodulin Sensing by Using FRET Strategy
    • Authors: Hongbo Yuan; Junjie Qi, Chengfen Xing, Hailong An, Ruimin Niu, Yong Zhan, Yibing Fan, Wenmin Yan, Ruihua Li, Bing Wang, Shu Wang
      Pages: 4412 - 4418
      Abstract: The conformation of calmodulin (CaM) changes from closed configuration to open one, converting to a claviform dumbbell‐shaped biomolecule upon Ca2+‐binding. A hybrid probe of graphene oxide (GO) cationic conjugated polymer for detection of the conformation transition of CaM by using FRET technique is demonstrated. The stronger hydrophobic interaction and weaker electrostatic repulsion leads to more CaM adsorption to the surface of GO upon binding with Ca2+ than that of CaM in the absence of Ca2+ (apoCaM), resulting in much farther proximity between poly[(9,9‐bis(6′‐N,N,N‐trimethy­lammonium)hexyl)‐fluorenylene phenylene dibromide] (PFP) and green fluorescent protein labeled at the N‐terminus of CaM and therefore much weaker FRET efficiency for PFP/Ca2+/CaM in comparison with that of PFP/apoCaM in the presence of GO. Notably, the assembly of CaM with GO is quantitatively and reversibly controlled by Ca2+ ions. A hybrid probe of graphene oxide cationic conjugated polymer is demonstrated for the detection of Ca2+‐induced conformation changes of calmodulin by using FRET technique is demonstrated. The detection is based on the electrostatic and hydrophobic interactions between CaM and GO, and the assembly of CaM with GO is quantitatively and reversibly controlled by Ca2+ ions.
      PubDate: 2015-06-05T02:18:51.991675-05:
      DOI: 10.1002/adfm.201501668
       
  • High Quality Carbon Nanotubes on Conductive Substrates Grown at Low
           Temperatures
    • Authors: Muhammad Ahmad; Jose V. Anguita, Vlad Stolojan, Tony Corless, Jeng‐Shiung Chen, J. David Carey, S. Ravi P. Silva
      Pages: 4419 - 4429
      Abstract: For carbon nanotubes (CNTs) to be exploited in electronic applications, the growth of high quality material on conductive substrates at low temperatures (
      PubDate: 2015-06-08T08:43:43.170861-05:
      DOI: 10.1002/adfm.201501214
       
  • Improved Heat Spreading Performance of Functionalized Graphene in
           Microelectronic Device Application
    • Authors: Yong Zhang; Haoxue Han, Nan Wang, Pengtu Zhang, Yifeng Fu, Murali Murugesan, Michael Edwards, Kjell Jeppson, Sebastian Volz, Johan Liu
      Pages: 4430 - 4435
      Abstract: It is demonstrated that a graphene‐based film (GBF) functionalized with silane molecules strongly enhances thermal performance. The resistance temperature detector results show that the inclusion of silane molecules doubles the heat spreading ability. Furthermore, molecular dynamics simulations show that the thermal conductivity (κ) of the GBF increased by 15%–56% with respect to the number density of molecules compared to that with the nonfunctionalized graphene substrate. This increase in κ is attributed to the enhanced in‐plane heat conduction of the GBF, resulting from the simultaneous increase of the thermal resistance between the GBF and the functionalized substrate limiting cross‐plane phonon scattering. Enhancement of the thermal performance by inserting silane‐functionalized molecules is important for the development of next‐generation electronic devices and proposed application of GBFs for thermal management. Graphene‐based film (GBF) functionalized with silane molecules doubles the heat spreading ability. Molecular dynamics (MD) simulations show that the thermal conductivity (κ) of the GBF increased by 15%–56% compared to that with the nonfunctionalized graphene substrate. The enhancement of the thermal performance by inserting silane‐functionalized molecules holds great potential for applications in thermal management field.
      PubDate: 2015-06-05T10:24:50.288952-05:
      DOI: 10.1002/adfm.201500990
       
  • Mesoporous Carbon Nanocube Architecture for High‐Performance
           Lithium–Oxygen Batteries
    • Authors: Bing Sun; Shuangqiang Chen, Hao Liu, Guoxiu Wang
      Pages: 4436 - 4444
      Abstract: One of the major challenges to develop high‐performance lithium–oxygen (Li–O2) battery is to find effective cathode catalysts and design porous architecture for the promotion of both oxygen reduction reactions and oxygen evolution reactions. Herein, the synthesis of mesoporous carbon nanocubes as a new cathode nanoarchitecture for Li–O2 batteries is reported. The oxygen electrodes made of mesoporous carbon nanocubes contain numerously hierarchical mesopores and macropores, which can facilitate oxygen diffusion and electrolyte impregnation throughout the electrode, and provide sufficient spaces to accommodate insoluble discharge products. When they are applied as cathode catalysts, the Li–O2 cells deliver discharge capacities of 26 100 mA h g−1 at 200 mA g−1, which is much higher than that of commercial carbon black catalysts. Furthermore, the mesoporous nanocube architecture can also serve as a conductive host structure for other highly efficient catalysts. For instance, the Ru functionalized mesoporous carbon nanocubes show excellent catalytic activities toward oxygen evolution reactions. Li–O2 batteries with Ru functionalized mesoporous carbon nanocube catalysts demonstrate a high charge/discharge electrical energy efficiency of 86.2% at 200 mA g−1 under voltage limitation and a good cycling performance up to 120 cycles at 400 mA g−1 with the curtaining capacity of 1000 mA h g−1. Mesoporous carbon nanocubes (MCCs) are synthesized by a chemical vapor deposition method. Oxygen electrode made of MCCs contains a hierarchical porous structure, which can facilitate oxygen diffusion, electrolyte impregnation, and accommodation of discharge products during the charge and discharge processes.
      PubDate: 2015-06-10T22:57:37.881592-05:
      DOI: 10.1002/adfm.201500863
       
  • Creation of Liquid Metal 3D Microstructures Using Dielectrophoresis
    • Authors: Shi‐Yang Tang; Jiuyang Zhu, Vijay Sivan, Berrak Gol, Rebecca Soffe, Wei Zhang, Arnan Mitchell, Khashayar Khoshmanesh
      Pages: 4445 - 4452
      Abstract: Patterning customized arrays of microscale Galinstan or EGaIn liquid metals enables the creation of a variety of microfabricated systems. Current techniques for creating microsized 3D structures of liquid metals are limited by the large dimension or low aspect ratio of such structures, and time‐consuming processes. Here, a novel technique for creating 3D microstructures of Galinstan using dielectrophoresis is introduced. The presented technique enables the rapid creation of Galinstan microstructures with various dimensions and aspect ratios. Two series of proof‐of‐concept experiments are conducted to demonstrate the capabilities of this technique. First, the 3D Galinstan microstructures are utilized as 3D microelectrodes to enhance the trapping of tungsten trioxide (WO3) nanoparticles flowing through a microfluidic channel. Second, the patterned Galinstan microstructures are utilized as microfins to improve the dissipation of heat within a microfluidic channel that is located onto a hot spot. The presented technique can be readily used for creating customized arrays of 3D Galinstan microstructures for a wide range of applications. This work introduces a novel technique for creating 3D microstructures of Galinstan using dielectrophoresis. It enables the rapid formation of multiple microstructures with controllable diameters and aspect ratios. Proof‐of‐concept experiments are conducted by utilizing the patterned microstructures as 3D microelectrodes for enhancing the trapping of suspended nanoparticles, and as microfins to improve the convective heat transfer within a microfluidic channel.
      PubDate: 2015-06-09T06:46:42.303518-05:
      DOI: 10.1002/adfm.201501296
       
  • “Layer‐Filter Threshold” Technique for
           Near‐Infrared Laser Ablation in Organic Semiconductor Device
           Processing
    • Authors: Feng Ye; Zhaobin Chen, Xiaoli Zhao, Jiayue Chen, Xiaoniu Yang
      Pages: 4453 - 4461
      Abstract: Although conventional laser ablation (CLA) method has widely been used in patterning of organic semiconductor thin films, its quality control still remains unsatisfied due to the ambiguous photochemical and photothermal processes. Based on industrial available near‐infrared laser source, herein, a novel “layer‐filter threshold” (LFT) technique is proposed, which involves the decomposition of targeted “layer‐filter” and subsequent explosive evaporation process to purge away the upper layers instead of layer‐by‐layer ablation. For photovoltaic device with structure of metal/blend/PEDOT:PSS/ITO/glass, the PEDOT:PSS layer as the “layer‐filter” is first demonstrated to be effective, and then the merged P1–P2 line and metal electrode layer are readily patterned through the “self‐aligned” effect and regulation of ablation direction, respectively. The correlation between laser fluence and explosive ablation efficacy is also investigated. Finally, photovoltaic modules based on classical P3HT:PC61BM and low‐bandgap PBDT‐TFQ:PC71BM systems are separately fabricated following the LFT technique. It is found that over 90% of geometric fill factor is achieved while device performances maintain in a limited change with increased number of series cells. In comparison to conventional laser ablation methods, the LFT technique does not require sophisticated instruments but reaches comparable processing accuracy, which shows promising potential in the fabrication and commercialization of organic semiconductor thin‐film devices. Layer‐filter threshold (LFT) technique based on near‐infrared laser is proposed and demonstrated, which enables the patterning strategy through an interlayer explosion effect with high precision and easily reachable operating conditions. Thus obtained organic photovoltaic modules reach geometric fill factors exceeding 90% and maintain the performances with increasing number of interconnected cells, which verifies the potential of LFT technique in the patterning of organic semiconductor devices.
      PubDate: 2015-06-10T22:56:46.477912-05:
      DOI: 10.1002/adfm.201501688
       
  • A Surface Tailoring Method of Ultrathin Polymer Gate Dielectrics for
           Organic Transistors: Improved Device Performance and the Thermal Stability
           Thereof
    • Authors: Hyejeong Seong; Jieung Baek, Kwanyong Pak, Sung Gap Im
      Pages: 4462 - 4469
      Abstract: Tailoring the surface of the dielectric layer is of critical importance to form a good interface with the following channel layer for organic thin film transistors (OTFTs). Here, a simple surface treatment method is applied onto an ultrathin (
      PubDate: 2015-06-10T22:56:51.567592-05:
      DOI: 10.1002/adfm.201500952
       
  • Engineering Zeolitic‐Imidazolate Framework (ZIF) Thin Film Devices
           for Selective Detection of Volatile Organic Compounds
    • Authors: Min Tu; Suttipong Wannapaiboon, Kira Khaletskaya, Roland A. Fischer
      Pages: 4470 - 4479
      Abstract: Thin films of sodalite‐type zeolitic‐imidazolate frameworks (ZIFs, ZIF‐7, 8, 9, 67, 90, and ZIF‐65‐Zn) with different metal centers and functional moieties are fabricated on SiO2 coated quartz crystal microbalance (QCM) substrates using automatic program controlled repeated direct growth method. The repeated direct growth procedure manipulated here shows great applicability for rapid growth of uniform ZIF thin films with controllable thickness. The fabricated ZIF/QCM devices are used to detect vapor phase volatile organic compounds including alcohol/water, BTEX compounds (benzene, toluene, ethylbenzene and xylene isomers), and hexane isomers. The ZIF/QCM devices exhibit selective detection behavior upon exposure to these chemical vapors. The effects of ZIF pore size, limited pore diameter, surface functionality, and structural flexibility on the sensing performances of ZIF/QCM devices are systematically investigated, which would be beneficial for the practical application of ZIF sensors based on array‐sensing technology. Furthermore, the selective adsorption behavior suggests that these ZIF materials have great potentials in the applications of biofuel recovery and the separation of benzene/cyclohexane, xylene, and hexane isomers. A convenient method is employed to fabricate uniform thin films of zeolitic‐imidazolate frameworks (ZIFs) with controllable thickness on silica coated quartz crystal microbalance (QCM) substrates. Because of the effects of ZIF pore size, limited pore diameter, surface functionality, and structural flexibility, the ZIF/QCM hybrid devices exhibit selective adsorption (detection) behavior upon exposure to various vapor phase volatile organic compounds.
      PubDate: 2015-06-12T06:02:37.133426-05:
      DOI: 10.1002/adfm.201500760
       
  • Polyoxometalate‐Modified Sponge‐Like Graphene Oxide Monolith
           with High Proton‐Conducting Performance
    • Authors: Yiwei Liu; Shumei Liu, Xuying Lai, Jun Miao, Danfeng He, Ning Li, Fang Luo, Zhan Shi, Shuxia Liu
      Pages: 4480 - 4485
      Abstract: Graphene oxide (GO) contains abundant oxygen‐containing functional groups acting as hydrogen bond acceptors for proton conduction on its basal plane. However, the dilemma in realizing bulk in‐plane conduction and the metastability at room temperature of GO films both obstruct its application. Polyoxometalate‐modified sponge‐like GO monolith (PEGO) with 3D cross‐linking inner structure, which exhibits unique “shrink‐expand” effect to polar solvent, are synthesized. Owing to the introduction of polyoxometalates and the replacement of unstable epoxy groups by ethylenediamine, PEGO exhibits hitherto the highest proton conductivity under low relative humidity (1.02 × 10−2 S cm−1 at 60% relative humidity) and excellent long‐term stability (more than 1 month). The outstanding conductivity originates from 3D transporting pathways, high‐density hopping sites, and eliminated grain boundary resistance. This study provides a practical way to design GO‐based proton‐conducting material dominated by in‐plane diffusion. Polyoxomatelate‐modified sponge‐like graphene oxide monolith with 3D cross‐linked inner structure is synthesized. The excellent proton conductivity originates from 3D transporting pathways, higher content of hopping sites, more delocalized hydrogen ions, and eliminated grain boundary resistance. This study provides a practical way to design GO‐based proton‐conducting material dominated by in‐plane diffusion.
      PubDate: 2015-06-16T12:41:35.329918-05:
      DOI: 10.1002/adfm.201501912
       
  • Aligned Carbon Nanotube–Based Flexible Gel Substrates for
           Engineering Biohybrid Tissue Actuators
    • Authors: Su Ryon Shin; Courtney Shin, Adnan Memic, Samaneh Shadmehr, Mario Miscuglio, Hyun Young Jung, Sung Mi Jung, Hojae Bae, Ali Khademhosseini, Xiaowu (Shirley) Tang, Mehmet R. Dokmeci
      Pages: 4486 - 4495
      Abstract: Muscle‐based biohybrid actuators have generated significant interest as the future of biorobotics but so far they move without having much control over their actuation behavior. Integration of microelectrodes into the backbone of these systems may enable guidance during their motion and allow precise control over these actuators with specific activation patterns. Here, this challenge is addressed by developing aligned carbon nanotube (CNT) forest microelectrode arrays and incorporating them into scaffolds for cell stimulation. Aligned CNTs are successfully embedded into flexible and biocompatible hydrogels exhibiting excellent anisotropic electrical conductivity. Bioactuators are then engineered by culturing cardiomyocytes on the CNT microelectrode‐integrated hydrogel constructs. The resulting cardiac tissue shows homogeneous cell organization with improved cell‐to‐cell coupling and maturation, which is directly related to the contractile force of muscle tissue. This centimeter‐scale bioactuator has excellent mechanical integrity, embedded microelectrodes, and is capable of spontaneous actuation behavior. Furthermore, it is demonstrated that a biohybrid machine can be controlled by an external electrical field provided by the integrated CNT microelectrode arrays. In addition, due to the anisotropic electrical conductivity of the electrodes provided by aligned CNTs, significantly different excitation thresholds are observed in different configurations such as the ones with electrical fields applied in directions parallel versus perpendicular to the CNT alignment. Aligned carbon nanotubes (CNTs) are successfully embedded into flexible and biocompatible self‐standing cardiac muscle tissue exhibiting excellent anisotropic electrical conductivity. This centimeter‐scale biohybrid machine has excellent mechanical integrity, embedded micro­electrodes, and is capable of spontaneous linear cyclic contraction/extension actuation. It is demonstrated that a biohybrid machine can be controlled by electrical signals provided by integrated CNT microelectrode arrays.
      PubDate: 2015-06-12T06:03:31.076458-05:
      DOI: 10.1002/adfm.201501379
       
  • Stomata‐Inspired Membrane Produced Through Photopolymerization
           Patterning
    • Authors: Hyejeong Kim; Sang Joon Lee
      Pages: 4496 - 4505
      Abstract: The programmed movements of responsive functional hydrogels have received much attention because of their abundant functions and wide range of engineering applications. In this study, an innovative stomata‐inspired membrane (SIM) is fabricated by using a temperature‐responsive hydrogel through a simple, cost‐effective, and high‐throughput patterned photopolymerization. Polymerization‐induced diffusion on the macroscale surface results in formation of a double‐parted polymer membrane with fine pores after single illumination. After heating the SIM, the less deformable thick frame supports the whole structure and the highly deformable thin base regulates pore shape. Among various SIM types, the slit pores of monocot SIM, which are lined up in parallel, exhibit the largest radius deformation. The morphological configuration of the SIM can be easily controlled by changing the photomask for a given application. As the developed SIM features the sensing‐to‐activation functions of stimuli‐responsive hydrogels and can be easily fabricated, this membrane can be potentially used for numerous practical applications, such as filter membranes with adjustable pores, membrane‐based sensors, membrane‐based actuators, and multifunctional membranes. An innovative stomata‐inspired membrane (SIM) is fabricated by using a temperature‐responsive hydrogel through a patterned photopolymerization. Polymerization‐induced diffusion on the macroscale surface results in formation of a double‐parted polymer membrane with controllable pores in single illumination, and each part exhibits different mechanical functions. The easily fabricated sensing‐to‐actuation functions of SIM can be used in numerous practical applications.
      PubDate: 2015-06-13T02:42:45.085816-05:
      DOI: 10.1002/adfm.201501445
       
  • Semi‐Egg‐Like Heterogeneous Compartmentalization of Cells
           Controlled by Contact Angle Hysteresis
    • Authors: Kang Sun; Mingjie Liu, Hongliang Liu, Pengchao Zhang, Junbing Fan, Jingxin Meng, Shutao Wang
      Pages: 4506 - 4511
      Abstract: Precise control of liquid inside compartments is critically important in bioreactors, combinatorial analysis, and tissue engineering. A contact angle hysteresis (CAH)‐based strategy is demonstrated to construct a semi‐egg‐like hydrogel architecture, leading to spatial heterogeneous compartmentalization of cells. The semi‐egg‐like architecture is fabricated by successively capturing and gelling prehydrogel liquids using a substrate with controlled‐CAH pattern and ultralow‐CAH background. The controlled‐CAH pattern could capture liquid with tunable size, while ultralow‐CAH background prevents liquid sticking. It is envisioned that this CAH‐based strategy would be promising in designing functional surface for engineering complicated architectures of either biomedical or nonbiomedical systems. From bad to good: Large contact angle hysteresis (CAH, defined by θA − θR) that causes pinning of droplet on surface is often an unfavorable factor in surface chemistry. It is, however, harnessed in constructing a semi‐egg‐like hydrogel for 3D heterogeneous compartmentalization of cells. By designing surface with controlled‐CAH patterns and ultralow‐CAH background, the semi‐egg‐like architecture is fabricated by dip‐coating in a facile way.
      PubDate: 2015-06-12T05:51:09.384284-05:
      DOI: 10.1002/adfm.201501527
       
  • Performances of Liquid‐Exfoliated Transition Metal Dichalcogenides
           as Hole Injection Layers in Organic Light‐Emitting Diodes
    • Authors: Cheolmin Kim; Thang Phan Nguyen, Quyet Van Le, Jong‐Myeong Jeon, Ho Won Jang, Soo Young Kim
      Pages: 4512 - 4519
      Abstract: 2D transition metal dichalcogenide (TMD) nanosheets, including MoS2, WS2, and TaS2, are used as hole injection layers (HILs) in organic light‐emitting diodes (OLEDs). MoS2, WS2, and TaS2 nanosheets are prepared using an exfoliation by ultrasonication method. The thicknesses and sizes of the TMD nanosheets are measured to be 3.1–4.3 nm and more than 100 nm, respectively. The work functions of the TMD nanosheets increase from 4.4–4.9 to 4.9–5.1 eV following ultraviolet/ozone (UVO) treatment. The turn‐on voltages at 10 cd m−2 for UVO‐treated TMD‐based devices decrease from 7.3–12.8 to 4.3–4.4 V and maximum luminance efficiencies increase from 5.74–9.04 to 12.01–12.66 cd A−1. In addition, this study confirms that the stabilities of the devices in air can be prolonged by using UVO‐treated TMDs as HILs in OLEDs. These results demonstrate the great potential of liquid‐exfoliated TMD nanosheets for use as HILs in OLEDs. 2D transition metal dichalcogenide (TMD) nanosheets, including MoS2, WS2, and TaS2, are used as hole injection layers (HILs) in organic light‐emitting diodes (OLEDs). MoS2, WS2, and TaS2 nanosheets are prepared using an exfoliation by an ultrasonication method. It is shown that the stability of the devices in air can be prolonged by using UV/ozone‐treated TMDs as HILs in OLEDs.
      PubDate: 2015-06-15T13:34:28.227905-05:
      DOI: 10.1002/adfm.201501333
       
  • Does Electronic Type Matter when Single‐Walled Carbon Nanotubes are
           Used for Electrode Applications?
    • Authors: G. Dinesha M. R. Dabera; M. R. Ranga Prabhath, Khue T. Lai, K. D. G. Imalka Jayawardena, F. Laurent M. Sam, Lynn J. Rozanski, A. A. Damitha T. Adikaari, S. Ravi P. Silva
      Pages: 4520 - 4530
      Abstract: Single‐walled carbon nanotube (SWNT) electrodes that are chemically and mechanically robust are fabricated using a simple drop cast method with thermal annealing and acid treatment. An electronic‐type selective decrease in sheet resistance of SWNT electrodes with HNO3 treatment is shown. Semiconducting SWNTs show a significantly higher affinity toward hole doping in comparison to metallic SWNTs; a ≈12‐fold and a ≈fivefold drop in sheet resistance, respectively. The results suggest the insignificance of the electronic type of the SWNTs for the film conductivity after hole doping. The SWNT films have been employed as transparent hole extracting electrodes in bulk heterojunction (BHJ) organic photovoltaics. Performances of the devices enlighten the fact that the electrode film morphology dominates over the electronic type of the doped SWNTs with similar sheet resistance and optical transmission. The power conversion efficiency (PCE) of 4.4% for the best performing device is the best carbon nanotube transparent electrode incorporated large area BHJ solar cell reported to date. This PCE is 90% in terms of PCEs achieved using indium tin oxide (ITO) based reference devices with identical film fabrication parameters indicating the potential of the SWNT electrodes as an ITO replacement toward realization of all carbon solar cells. Fabrication of electronic‐type separated single‐walled carbon nanotube (SWNT) electrodes for organic solar cells, using a simple drop cast method followed by thermal and acid treatment. The thermal and acid treatment processes significantly enhance the conductivity of the SWNT films, enabling the use of the conductivity‐enhanced SWNT layers as hole extracting, transparent electrodes in organic bulk heterojunction solar cells.
      PubDate: 2015-06-15T13:34:35.557294-05:
      DOI: 10.1002/adfm.201501394
       
  • Hybrid Organic/Inorganic Nanostructures for Highly Sensitive
           Photoelectrochemical Detection of Dissolved Oxygen in Aqueous Media
    • Authors: Sebastiano Bellani; Ali Ghadirzadeh, Laura Meda, Alberto Savoini, Alessandra Tacca, Gianluigi Marra, Rui Meira, Jorge Morgado, Fabio Di Fonzo, Maria Rosa Antognazza
      Pages: 4531 - 4538
      Abstract: Precise, reliable, and remote measurement of dissolved oxygen in aqueous media is of great importance for many industrial, environmental, and biological applications. In particular, photoelectrochemical sensors working in differential mode have recently demonstrated promising properties, in terms of stability, sensitivity, and application potential. Here, a new approach is presented, combining visible light sensitivity, efficient photocurrent generation, and solution‐processed fabrication methods of conjugated polymers, with charge carriers selectivity, energetic alignment favorable to efficient interfacial charge transfer and high surface area achievable by using metal oxide nanostructures. Extensive characterization and optimization of the hybrid organic/inorganic system are carried out, leading to the realization of an oxygen sensor device, based on nanostructured palladium oxide/poly[(9,9‐dioctylfluorenyl‐2,7‐diyl)‐alt‐5,5‐(4′,7′‐di‐2‐thienyl‐2′,1′,3′‐benzothiadiazole]/[6,6]phenyl‐C61‐butyric acid methyl ester (PdO/APFO‐3:PCBM) as materials of choice. State‐of‐the‐art sensitivity, amounting at −5.87 μA cm−2 ppm−1, low background signal, in the order of −4.85 μA cm−2, good electrochemical stability for more than 2 h of continuous functioning and high reproducibility of the signal over the pH 1 to 10 range, are reported, making the hybrid device suitable for several practical uses. The results fully validate the mixed organic/inorganic approach for photoelectrochemical applications, and pave the way for its further exploitation in fields like waste water treatment, environmental monitoring, and water splitting. A photoelectrochemical sensor for dissolved oxygen, based on the hybrid interface between an organic semiconductor and a nanostructured metal oxide, is realized. State‐of‐the‐art sensitivity, good electrochemical stability, and high reproducibility in different environmental conditions, ranging from acid to basic pH, are reported, making the polymer‐based device suitable for applications in waste water treatment, environmental monitoring and water splitting.
      PubDate: 2015-06-16T12:41:41.957081-05:
      DOI: 10.1002/adfm.201500701
       
  • Roll‐to‐Roll Printed Silver Nanowire Semitransparent
           Electrodes for Fully Ambient Solution‐Processed Tandem Polymer Solar
           Cells
    • Authors: Dechan Angmo; Thomas R. Andersen, Janet J. Bentzen, Martin Helgesen, Roar R. Søndergaard, Mikkel Jørgensen, Jon E. Carlé, Eva Bundgaard, Frederik C. Krebs
      Pages: 4539 - 4547
      Abstract: Silver nanowires (AgNWs) and zinc oxide (ZnO) are deposited on flexible substrates using fast roll‐to‐roll (R2R) processing. The AgNW film on polyethylene terephthalate (PET) shows >80% uniform optical transmission in the range of 550–900 nm. This electrode is compared to the previously reported and currently widely produced indium‐tin‐oxide (ITO) replacement comprising polyethylene terephthalate (PET) silver grid poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) ZnO known as Flextrode. The AgNW/ZnO electrode shows higher transmission than Flextrode above 490 nm in the electromagnetic spectrum reaching up to 40% increased transmission at 750 nm in comparison to Flextrode. The functionality of AgNW electrodes is demonstrated in single and tandem polymer solar cells and compared with parallel devices on traditional Flextrode. All layers, apart from the semitransparent electrodes which are large‐scale R2R produced, are fabricated in ambient conditions on a laboratory roll‐coater using printing and coating methods which are directly transferrable to large‐scale R2R processing upon availability of materials. In a single cell structure, Flextrode is preferable with active layers based on poly‐3‐hexylthiophene(P3HT):phenyl‐C61‐butyric acid methylester (PCBM) and donor polymers of similar absorption characteristics while AgNW/ZnO electrodes are more compatible with low band gap polymer‐based single cells. In tandem devices, AgNW/ZnO is more preferable resulting in up to 80% improvement in PCE compared to parallel devices on Flextrode. Rolling in tandem: Roll‐to‐roll rotary screen printing of silver nanowires (AgNWs) and zinc oxide (ZnO) is realized on flexible substrates enabling large‐area semi‐transparent electrodes with >80% transmission. This electrode is employed in all‐ambient roll‐coating of single and tandem polymer solar cells. AgNW/ZnO proves highly suitable especially for tandem structures while the traditional indium‐tin‐oxide replacement—Flextrode—remains unbeaten in single cells with wide band‐gap polymers.
      PubDate: 2015-06-18T11:42:56.572506-05:
      DOI: 10.1002/adfm.201501887
       
  • Bioinspired Graphene Actuators Prepared by Unilateral UV Irradiation of
           Graphene Oxide Papers
    • Authors: Dong‐Dong Han; Yong‐Lai Zhang, Yan Liu, Yu‐Qing Liu, Hao‐Bo Jiang, Bing Han, Xiu‐Yan Fu, Hong Ding, Huai‐Liang Xu, Hong‐Bo Sun
      Pages: 4548 - 4557
      Abstract: Inspired by natural autonomous systems that demonstrate controllable shape, appearance, and actuation under external stimuli, a facile preparation of moisture responsive graphene‐based smart actuators by unilateral UV irradiation of graphene oxide (GO) papers is reported. UV irradiation of GO is found to be an effective protocol to trigger the reduction of GO; however, due to the limited light transmittance and thermal relaxation, thick GO paper cannot be fully reduced. Consequently, by tuning the photoreduction gradient, anisotropic GO/reduced GO (RGO) bilayer structure can be easily prepared toward actuation application. To get better control over the responsive properties, GO/RGO bilayer paper with a certain curvature and RGO patterns are successfully prepared for actuator design. As representative examples, smart humidity‐driven graphene actuators that mimic the cilia of respiratory tract and tendril climber plant are successfully developed for controllable objects transport. A facile preparation of graphene actuators by unilateral UV irradiation of graphene oxide (GO) papers is reported. Anisotropic GO/reduced GO bilayer paper can be directly prepared by controlling the photoreduction gradient. As typical examples, smart humidity‐driven graphene actuators that mimic the cilia of respiratory tract and the tendril climber plant are developed for object transport.
      PubDate: 2015-06-16T12:41:51.220437-05:
      DOI: 10.1002/adfm.201501511
       
  • Metal‐Organic Frameworks: Tunable Photodynamic Switching of
           DArE@PAF‐1 for Carbon Capture (Adv. Funct. Mater. 28/2015)
    • Authors: Richelle Lyndon; Kristina Konstas, Richard A. Evans, Daniel J. Keddie, Matthew R. Hill, Bradley P. Ladewig
      Pages: 4559 - 4559
      Abstract: A new type of photodynamic carbon capture material with up to 26 wt% CO2 desorption capacity is synthesized via incorporation of diarylethene as guest molecules in porous aromatic framework‐1. As reported by M. R. Hill, B. P. Ladewig, and colleagues on page 4405, this material can simply adsorb and desorb carbon dioxide on application of broad spectrum light similar to sunlight.
      PubDate: 2015-07-21T06:19:18.009646-05:
      DOI: 10.1002/adfm.201570193
       
  • Conformation Changes: Graphene‐Oxide‐Conjugated Polymer Hybrid
           Materials for Calmodulin Sensing by Using FRET Strategy (Adv. Funct.
           Mater. 28/2015)
    • Authors: Hongbo Yuan; Junjie Qi, Chengfen Xing, Hailong An, Ruimin Niu, Yong Zhan, Yibing Fan, Wenmin Yan, Ruihua Li, Bing Wang, Shu Wang
      Pages: 4560 - 4560
      Abstract: A novel and unconventional hybrid material consisting of graphene oxide (GO) and positively charged organic polymer for detection of the conformation transition of calmodulin by using fluorescence resonance energy transfer (FRET) technique is developed on page 4412 by C. Xing, Y. Zhan, S. Wang, and co‐workers. This effort provides first example of how FRET technique can be used with GO and optical functional materials to detect CaM.
      PubDate: 2015-07-21T06:19:17.411457-05:
      DOI: 10.1002/adfm.201570194
       
 
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327
 
About JournalTOCs
API
Help
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-2015