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Journal Cover Advanced Materials
  [SJR: 9.021]   [H-I: 345]   [259 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0935-9648 - ISSN (Online) 1521-4095
   Published by John Wiley and Sons Homepage  [1579 journals]
  • Gold and Hairpin DNA Functionalization of Upconversion Nanocrystals for
           Imaging and In Vivo Drug Delivery
    • Authors: Sanyang Han; Animesh Samanta, Xiaoji Xie, Ling Huang, Juanjuan Peng, Sung Jin Park, Daniel Boon Loong Teh, Yongdoo Choi, Young-Tae Chang, Angelo Homayoun All, Yanmei Yang, Bengang Xing, Xiaogang Liu
      PubDate: 2017-10-20T07:15:21.694218-05:
      DOI: 10.1002/adma.201704811
       
  • 2D Materials: Metallic MXene Saturable Absorber for Femtosecond
           Mode-Locked Lasers (Adv. Mater. 40/2017)
    • Authors: Young In Jhon; Joonhoi Koo, Babak Anasori, Minah Seo, Ju Han Lee, Yury Gogotsi, Young Min Jhon
      Abstract: In article number 1702496, Ju Han Lee, Yury Gogotsi, Young Min Jhon, and co-workers demonstrate that 2D transition-metal carbides, nitrides, and carbonitides, called MXenes, can be excellent saturable absorbers to generate femtosecond mode-locked pulsed lasers in a fiber laser cavity. The promise of MXenes in broadband laser applications is suggested due to the wide range of superb optical absorptions, from the visible to the terahertz range, which results from the unique metallic characteristics.
      PubDate: 2017-10-20T07:15:21.646477-05:
      DOI: 10.1002/adma.201770292
       
  • Photothermal Therapy: 1D Coordination Polymer Nanofibers for
           Low-Temperature Photothermal Therapy (Adv. Mater. 40/2017)
    • Authors: Yu Yang; Wenjun Zhu, Ziliang Dong, Yu Chao, Lai Xu, Meiwan Chen, Zhuang Liu
      Abstract: One-dimensional nanoscale coordination polymers (1D NCPs) are fabricated by Lai Xu, Meiwan Chen, Zhuang Liu, and co-workers by simply mixing metal ions and the organic ligand indocyanine green together with polyhistidine–poly(ethylene-glycol) copolymer, and then further loading with gambogic acid, as described in article number 1703588. Such 1D NCPs with efficient pH-responsive tumor retention enables effective destruction of tumors under low-temperature photothermal heating, owing to the gambogic-acid-induced down-regulation of heat-shock protein 90 to overcome the thermal-resistance of tumor cells.
      PubDate: 2017-10-20T07:15:19.572973-05:
      DOI: 10.1002/adma.201770293
       
  • Masthead: (Adv. Mater. 40/2017)
    • PubDate: 2017-10-20T07:15:17.384499-05:
      DOI: 10.1002/adma.201770290
       
  • Perovskite Thin Films: High-Resolution Spin-on-Patterning of Perovskite
           Thin Films for a Multiplexed Image Sensor Array (Adv. Mater. 40/2017)
    • Authors: Woongchan Lee; Jongha Lee, Huiwon Yun, Joonsoo Kim, Jinhong Park, Changsoon Choi, Dong Chan Kim, Hyunseon Seo, Hakyong Lee, Ji Woong Yu, Won Bo Lee, Dae-Hyeong Kim
      Abstract: A novel patterning method for perovskite thin films is developed by Dae-Hyeong Kim and co-workers, which is described in article number 1702902. The patterning method (spin-on-patterning) is based on the thermodynamically preferred dewetting behavior of the perovskite precursor solution during the spin-coating process. By using this method, a high-performance, ultrathin, and deformable perovskite-on-silicon multiplexed image sensor array is successfully achieved.
      PubDate: 2017-10-20T07:15:17.322978-05:
      DOI: 10.1002/adma.201770288
       
  • Contents: (Adv. Mater. 40/2017)
    • PubDate: 2017-10-20T07:15:15.724107-05:
      DOI: 10.1002/adma.201770289
       
  • Photoconductivity: Giant Incident Photon-to-Current Conversion with
           Photoconductivity Gain on Nanostructured Bismuth Oxysulfide
           Photoelectrodes under Visible-Light Illumination (Adv. Mater. 40/2017)
    • Authors: Evgeny A. Bondarenko; Eugene A. Streltsov, Mikalai V. Malashchonak, Alexander V. Mazanik, Anatoly I. Kulak, Ekaterina V. Skorb
      Abstract: A kaleidoscope of nanostructured bismuth oxysulfide systems – the photoelectrode described by Eugene A. Streltsov, Ekaterina V. Skorb, and co-workers in article number 1702387 – which is synthesized by the easy and cheap chemical bath deposition method, is featured with a surprising giant incident photon-to-current conversion (IPCE about 2500%) under visible illumination. Light opens a channel for charge carriers from the external circuit to participate in the photoreduction process for a new generation of high-performance photodetectors and photostimulated charge pumping.
      PubDate: 2017-10-20T07:15:13.388964-05:
      DOI: 10.1002/adma.201770287
       
  • Self-Healing: Water-Enabled Healing of Conducting Polymer Films (Adv.
           Mater. 40/2017)
    • Authors: Shiming Zhang; Fabio Cicoira
      Abstract: Self-healing electronic materials can repair damage caused by external agents. Therefore, they are highly desirable for electronic devices. Fabio Cicoira and Shiming Zhang, in article number 1703098, find that films of the conducting polymer poly(3,4)ethylenedioxythiophene doped with polystyrene sulfonate (PEDOT:PSS) show instantaneous electronic healing after wetting the damaged area with water.
      PubDate: 2017-10-20T07:15:12.630958-05:
      DOI: 10.1002/adma.201770291
       
  • External-Field-Induced Gradient Wetting for Controllable Liquid Transport:
           From Movement on the Surface to Penetration into the Surface
    • Authors: Yan Li; Linlin He, Xiaofang Zhang, Na Zhang, Dongliang Tian
      Abstract: External-field-responsive liquid transport has received extensive research interest owing to its important applications in microfluidic devices, biological medical, liquid printing, separation, and so forth. To realize different levels of liquid transport on surfaces, the balance of the dynamic competing processes of gradient wetting and dewetting should be controlled to achieve good directionality, confined range, and selectivity of liquid wetting. Here, the recent progress in external-field-induced gradient wetting is summarized for controllable liquid transport from movement on the surface to penetration into the surface, particularly for liquid motion on, patterned wetting into, and permeation through films on superwetting surfaces with external field cooperation (e.g., light, electric fields, magnetic fields, temperature, pH, gas, solvent, and their combinations). The selected topics of external-field-induced liquid transport on the different levels of surfaces include directional liquid motion on the surface based on the wettability gradient under an external field, partial entry of a liquid into the surface to achieve patterned surface wettability for printing, and liquid-selective permeation of the film for separation. The future prospects of external-field-responsive liquid transport are also discussed.External-field-responsive liquid transport on different levels of surfaces, owing to the dynamic balance of gradient wetting and dewetting, are highlighted, including directional liquid motion on the surface based on the wettability gradient under an external field, partial entry of a liquid into a surface to achieve patterned surface wettability for printing, and liquid-selective permeation of the film for separation.
      PubDate: 2017-10-20T07:12:53.525623-05:
      DOI: 10.1002/adma.201703802
       
  • Organic Diode Rectifiers Based on a High-Performance Conjugated Polymer
           for a Near-Field Energy-Harvesting Circuit
    • Authors: Stuart G. Higgins; Tiziano Agostinelli, Steve Markham, Robert Whiteman, Henning Sirringhaus
      Abstract: Organic diodes manufactured on a plastic substrate capable of rectifying a high-frequency radio-frequency identification signal (13.56 MHz), with sufficient power to operate an interactive smart tag, are reported. A high-performance conjugated semiconductor (an indacenodithiophene-benzothiadiazole copolymer) is combined with a carefully optimized architecture to satisfy the electrical requirements for an organic-semiconductor-based logic chip.A high-performance conjugated polymer is shown to create fast organic rectifiers, which can be used in a near-field energy-harvesting circuit. The performance of this circuit is sufficient to power an interactive smart tag from a 13.56 MHz near-field communication source.
      PubDate: 2017-10-20T07:11:43.819622-05:
      DOI: 10.1002/adma.201703782
       
  • Hexagonal Sphericon Hematite with High Performance for Water Oxidation
    • Authors: Taiwo Odedairo; Xuecheng Yan, Xiangdong Yao, Kostya (Ken) Ostrikov, Zhonghua Zhu
      Abstract: A cost-effective hexagonal sphericon hematite with predominant (110) facets for the oxygen evolution reaction (OER) is demonstrated. Sequential incorporation of near-atomic uniformly distributed Ce species and Ni nanoparticles into selected sites of the hematite induces a complex synergistic integration phenomenon that enhances the overall catalytic OER performance. This cheap hexagonal sphericon hematite (Fe ≈ 98%) only needs a small overpotential (η) of 0.34 V to reach 10 mA cm−2, superior to commercial IrO2 and more expensive Co-, Ni-, and Li-based electrocatalysts.A cost-effective hexagonal sphericon hematite (Fe ≈ 98%) with predominant (110) facets for oxygen evolution reaction (OER) is demonstrated. Sequential incorporation of near-atomic uniformly distributed Ce species and Ni nanoparticles into selected sites of the hematite induces a complex synergistic integration phenomenon that enhances the overall catalytic OER performance.
      PubDate: 2017-10-20T07:11:24.638392-05:
      DOI: 10.1002/adma.201703792
       
  • Platinum-Based Nanowires as Active Catalysts toward Oxygen Reduction
           Reaction: In Situ Observation of Surface-Diffusion-Assisted, Solid-State
           Oriented Attachment
    • Authors: Yanling Ma; Wenpei Gao, Hao Shan, Wenlong Chen, Wen Shang, Peng Tao, Chengyi Song, Chris Addiego, Tao Deng, Xiaoqing Pan, Jianbo Wu
      Abstract: Facile fabrication of advanced catalysts toward oxygen reduction reaction with improving activity and stability is significant for proton-exchange membrane fuel cells. Based on a generic solid-state reaction, this study reports a modified hydrogen-assisted, gas-phase synthesis for facile, scalable production of surfactant-free, thin, platinum-based nanowire-network electrocatalysts. The free-standing platinum and platinum–nickel alloy nanowires show improvements of up to 5.1 times and 10.9 times for mass activity with a minimum 2.6% loss after an accelerated durability test for 10k cycles; 8.5 times and 13.8 times for specific activity, respectively, compared to commercial Pt/C catalyst. In addition, combined with a wet impregnation method, different substrate-materials-supported platinum-based nanowires are obtained, which paves the way to practical application as a next-generation supported catalyst to replace Pt/C. The growth stages and formation mechanism are investigated by an in situ transmission electron microscopy study. It reveals that the free-standing platinum nanowires form in the solid state via metal-surface-diffusion-assisted oriented attachment of individual nanoparticles, and the interaction with gas molecules plays a critical role, which may represent a gas-molecular-adsorbate-modified growth in catalyst preparation.Free-standing platinum and platinum–nickel alloy nanowires are synthesized by a modified facile hydrogen-assisted gas-phase method. In situ transmission electron microscopy observation reveals that the formation of nanowires is attributed to surface-diffusion-assisted, solid-state oriented attachment. The Pt and Pt1.3Ni-alloy nanowires exhibit promising catalytic activity and excellent stability compared with commercial Pt/C toward oxygen reduction reaction.
      PubDate: 2017-10-20T06:28:47.665505-05:
      DOI: 10.1002/adma.201703460
       
  • Directed Self-Assembly of Liquid-Crystalline Molecular Building Blocks for
           Sub-5 nm Nanopatterning
    • Authors: Koen Nickmans; Albert P. H. J. Schenning
      Abstract: The thin-film directed self-assembly of molecular building blocks into oriented nanostructure arrays enables next-generation lithography at the sub-5 nm scale. Currently, the fabrication of inorganic arrays from molecular building blocks is restricted by the limited long-range order and orientation of the materials, as well as suitable methodologies for creating lithographic templates at sub-5 nm dimensions. In recent years, higher-order liquid crystals have emerged as functional thin films for organic electronics, nanoporous membranes, and templated synthesis, which provide opportunities for their use as lithographic templates. By choosing examples from these fields, recent progress toward the design of molecular building blocks is highlighted, with an emphasis on liquid crystals, to access sub-5 nm features, their directed self-assembly into oriented thin films, and, importantly, the fabrication of inorganic arrays. Finally, future challenges regarding sub-5 nm patterning with liquid crystals are discussed.Emerging approaches to sub-5 nm patterning with molecular building blocks are discussed, emphasizing the use of liquid-crystalline materials to access sub-5 nm features, their directed self-assembly into oriented thin films, and the fabrication of inorganic arrays. Examples are chosen from the established fields of organic electronics, nanoporous membranes, and templated synthesis, each of which provides opportunities for nanolithography.
      PubDate: 2017-10-20T06:27:57.885507-05:
      DOI: 10.1002/adma.201703713
       
  • A New Design Strategy for Efficient Thermally Activated Delayed
           Fluorescence Organic Emitters: From Twisted to Planar Structures
    • Authors: Xian-Kai Chen; Youichi Tsuchiya, Yuma Ishikawa, Cheng Zhong, Chihaya Adachi, Jean-Luc Brédas
      Abstract: In the traditional molecular design of thermally activated delayed fluorescence (TADF) emitters composed of electron-donor and electron-acceptor moieties, achieving a small singlet–triplet energy gap (ΔEST) in strongly twisted structures usually translates into a small fluorescence oscillator strength, which can significantly decrease the emission quantum yield and limit efficiency in organic light-emitting diode devices. Here, based on the results of quantum-chemical calculations on TADF emitters composed of carbazole donor and 2,4,6-triphenyl-1,3,5-triazine acceptor moieties, a new strategy is proposed for the molecular design of efficient TADF emitters that combine a small ΔEST with a large fluorescence oscillator strength. Since this strategy goes beyond the traditional framework of structurally twisted, charge-transfer type emitters, importantly, it opens the way for coplanar molecules to be efficient TADF emitters. Here, a new emitter, composed of azatriangulene and diphenyltriazine moieties, is theoretically designed, which is coplanar due to intramolecular H-bonding interactions. The synthesis of this hexamethylazatriangulene-triazine (HMAT-TRZ) emitter and its preliminary photophysical characterizations point to HMAT-TRZ as a potential efficient TADF emitter.A new strategy is proposed for the molecular design of efficient thermally activated delayed fluorescence (TADF) emitters that combine small singlet–triplet energy gaps and large fluorescence oscillator strengths. This strategy goes beyond the traditional framework of twisted TADF emitters and opens the way for coplanar molecules to be efficient TADF emitters.
      PubDate: 2017-10-17T07:37:44.708601-05:
      DOI: 10.1002/adma.201702767
       
  • Thiol–Ene Clickable Gelatin: A Platform Bioink for Multiple 3D
           Biofabrication Technologies
    • Authors: Sarah Bertlein; Gabriella Brown, Khoon S. Lim, Tomasz Jungst, Thomas Boeck, Torsten Blunk, Joerg Tessmar, Gary J. Hooper, Tim B. F. Woodfield, Juergen Groll
      Abstract: Bioprinting can be defined as the art of combining materials and cells to fabricate designed, hierarchical 3D hybrid constructs. Suitable materials, so called bioinks, have to comply with challenging rheological processing demands and rapidly form a stable hydrogel postprinting in a cytocompatible manner. Gelatin is often adopted for this purpose, usually modified with (meth-)acryloyl functionalities for postfabrication curing by free radical photopolymerization, resulting in a hydrogel that is cross-linked via nondegradable polymer chains of uncontrolled length. The application of allylated gelatin (GelAGE) as a thiol–ene clickable bioink for distinct biofabrication applications is reported. Curing of this system occurs via dimerization and yields a network with flexible properties that offer a wider biofabrication window than (meth-)acryloyl chemistry, and without additional nondegradable components. An in-depth analysis of GelAGE synthesis is conducted, and standard UV-initiation is further compared with a recently described visible-light-initiator system for GelAGE hydrogel formation. It is demonstrated that GelAGE may serve as a platform bioink for several biofabrication technologies by fabricating constructs with high shape fidelity via lithography-based (digital light processing) 3D printing and extrusion-based 3D bioprinting, the latter supporting long-term viability postprinting of encapsulated chondrocytes.Allylated gelatin as a thiol–ene clickable bioink platform provides application for distinct biofabrication techniques. Cross-linking of this cytocompatible system results in controlled homogeneous dimerized networks without additional nondegradable components, in contrast to conventional free radical polymerization. Moreover, UV- and visible-light initiation of the hydrogels are compared.
      PubDate: 2017-10-17T07:36:53.184885-05:
      DOI: 10.1002/adma.201703404
       
  • Lateral Graphene-Contacted Vertically Stacked WS2/MoS2 Hybrid
           Photodetectors with Large Gain
    • Authors: Haijie Tan; Wenshuo Xu, Yuewen Sheng, Chit Siong Lau, Ye Fan, Qu Chen, Martin Tweedie, Xiaochen Wang, Yingqiu Zhou, Jamie H. Warner
      Abstract: A demonstration is presented of how significant improvements in all-2D photodetectors can be achieved by exploiting the type-II band alignment of vertically stacked WS2/MoS2 semiconducting heterobilayers and finite density of states of graphene electrodes. The photoresponsivity of WS2/MoS2 heterobilayer devices is increased by more than an order of magnitude compared to homobilayer devices and two orders of magnitude compared to monolayer devices of WS2 and MoS2, reaching 103 A W−1 under an illumination power density of 1.7 × 102 mW cm−2. The massive improvement in performance is due to the strong Coulomb interaction between WS2 and MoS2 layers. The efficient charge transfer at the WS2/MoS2 heterointerface and long trapping time of photogenerated charges contribute to the observed large photoconductive gain of ≈3 × 104. Laterally spaced graphene electrodes with vertically stacked 2D van der Waals heterostructures are employed for making high-performing ultrathin photodetectors.WS2/MoS2 vertical heterostructures are known to have type-II band alignment and form layer-separated electron–hole pairs upon illumination. Lateral photodetectors based on WS2/MoS2 heterostacks with graphene electrodes are demonstrated using crystals grown by chemical vapor deposition. The unique device architecture results in superior photosensing performance with large photoconductive gain due to long-lived interlayer excitons and the photogating mechanism.
      PubDate: 2017-10-17T07:36:30.439048-05:
      DOI: 10.1002/adma.201702917
       
  • Engineering 2D Nanofluidic Li-Ion Transport Channels for Superior
           Electrochemical Energy Storage
    • Authors: Chunshuang Yan; Chade Lv, Yue Zhu, Gang Chen, Jingxue Sun, Guihua Yu
      Abstract: Rational surface engineering of 2D nanoarchitectures-based electrode materials is crucial as it may enable fast ion transport, abundant-surface-controlled energy storage, long-term structural integrity, and high-rate cycling performance. Here we developed the stacked ultrathin Co3O4 nanosheets with surface functionalization (SUCNs-SF) converted from layered hydroxides with inheritance of included anion groups (OH−, NO3−, CO32−). Such stacked structure establishes 2D nanofluidic channels offering extra lithium storage sites, accelerated Li-ion transport, and sufficient buffering space for volume change during electrochemical processes. Tested as an anode material, this unique nanoarchitecture delivers high specific capacity (1230 and 1011 mAh g−1 at 0.2 and 1 A g−1, respectively), excellent rate performance, and long cycle capability (1500 cycles at 5 A g−1). The demonstrated advantageous features by constructing 2D nanochannels in nonlayered materials may open up possibilities for designing high-power lithium ion batteries.The stacked ultrathin Co3O4 nanosheets with surface functionalization possess 2D nanofluidic channels for rapid Li-ion transport in both half- and full-cells.
      PubDate: 2017-10-17T07:35:59.416749-05:
      DOI: 10.1002/adma.201703909
       
  • Biomimetic Inspired Core–Canopy Quantum Dots: Ions Trapped in Voids
           Induce Kinetic Fluorescence Switching
    • Authors: Arpita Saha; Elena Oleshkevich, Clara Vinas, Francesc Teixidor
      Abstract: Closely packed hollow spheres connected through pillars to a CdSe quantum dot (QD) core produce channels through which ions navigate. This particular structure is well represented by [CdSe@CarbOPH(O)]@Cl/[N(Caprylyl)3Me1] indicating that in the channels between the canopy made by the carboranyl spheres (carboranylphosphinate, CarbOPH(O)) and the CdSe core exist chloride anions. Due to the close packing, the spheres produce openings. These are converted into gates because [N(Caprylyl)3Me1] acts as a plug. The [CdSe@CarbOPH(O)]@Cl/assembly is negatively charged because the Cd positive charges are outnumbered by the negative charges due to the Se, the phosphinic acid and, very importantly, the trapped chloride anions, and this negative load is compensated by the cationic surfactant. Here, it is shown that this synergism produces an unprecedented phenomenon, namely, kinetic fluorescence switching. It is observed that the material shines brightly then loses its brightness and, upon the application of kinetic energy, shines back to the maximum power. This process continues for an extended period of time, up to half a year, at least. This new type of architecture in QDs is named as core–canopy QDs. In this case, this study demonstrates one property, the kinetic fluorescence switching, as a consequence of the trapping of Cl− in the QDs channels, but other properties can be envisaged with the judicious choice of the anions or even the pillar connecting the hollow sphere with the ground.Quantum dots with the architecture of packed spheres/pillars/ground are prepared. This architecture generates inner channels and openings. The channels can be filled with ions, tuning the charge of the quantum dots' construction. The channels are filled with Cl−, inducing a negative charge in the assembly that is compensated by outer cations leading to unprecedented kinetic fluorescence switching.
      PubDate: 2017-10-17T07:35:01.272207-05:
      DOI: 10.1002/adma.201704238
       
  • Bioinspired Heterogeneous Structural Color Stripes from Capillaries
    • Authors: Ze Zhao; Huan Wang, Luoran Shang, Yunru Yu, Fanfan Fu, Yuanjin Zhao, Zhongze Gu
      Abstract: As an important characteristic of many creatures, structural colors play a crucial role in the survival of organisms. Inspired by these features, an intelligent structural color material with a heterogeneous striped pattern and stimuli-responsivity by fast self-assembly of colloidal nanoparticles in capillaries with a certain diameter range are presented here. The width, spacing, color, and even combination of the structural color stripe patterns can be precisely tailored by adjusting the self-assembly parameters. Attractively, with the integration of a near-infrared (NIR) light responsive graphene hydrogel into the structural color stripe pattern, the materials are endowed with light-controlled reversible bending behavior with self-reporting color indication. It is demonstrated that the striped structural color materials can be used as NIR-light-triggered dynamic barcode labels for the anti-counterfeiting of different products. These features of the bioinspired structural color stripe pattern materials indicate their potential values for mimicking structural color organisms, which will find important applications in constructing intelligent sensors, anti-counterfeiting devices, and so on.Bioinspired structural color stripes with tailorable width, spacing, color, and even combination of the colored patterns are generated by assembling colloidal nanoparticles in capillaries. With the integration of a graphene hydrogel, the materials are endowed with NIR-light-controlled reversible bending behavior with self-reporting color indication, which also show a great potential anti-counterfeiting application as NIR-light-triggered dynamic barcode labels.
      PubDate: 2017-10-17T07:32:59.009938-05:
      DOI: 10.1002/adma.201704569
       
  • Planar-Structure Perovskite Solar Cells with Efficiency beyond 21%
    • Authors: Qi Jiang; Zema Chu, Pengyang Wang, Xiaolei Yang, Heng Liu, Ye Wang, Zhigang Yin, Jinliang Wu, Xingwang Zhang, Jingbi You
      Abstract: Low temperature solution processed planar-structure perovskite solar cells gain great attention recently, while their power conversions are still lower than that of high temperature mesoporous counterpart. Previous reports are mainly focused on perovskite morphology control and interface engineering to improve performance. Here, this study systematically investigates the effect of precise stoichiometry, especially the PbI2 contents on device performance including efficiency, hysteresis and stability. This study finds that a moderate residual of PbI2 can deliver stable and high efficiency of solar cells without hysteresis, while too much residual PbI2 will lead to serious hysteresis and poor transit stability. Solar cells with the efficiencies of 21.6% in small size (0.0737 cm2) and 20.1% in large size (1 cm2) with moderate residual PbI2 in perovskite layer are obtained. The certificated efficiency for small size shows the efficiency of 20.9%, which is the highest efficiency ever recorded in planar-structure perovskite solar cells, showing the planar-structure perovskite solar cells are very promising.This study obtains planar-structure perovskite solar cells with the efficiencies of 21.6% in small size (0.0737 cm2) and 20.1% in large size (1 cm2) with moderate residual PbI2 in perovskite layer. The certi­ficated efficiency for small size shows the efficiency of 20.9%, which is the highest efficiency ever recorded in planar-structure perovskite solar cells.
      PubDate: 2017-10-16T07:55:55.420896-05:
      DOI: 10.1002/adma.201703852
       
  • Flexible, High-Wettability and Fire-Resistant Separators Based on
           Hydroxyapatite Nanowires for Advanced Lithium-Ion Batteries
    • Authors: Heng Li; Dabei Wu, Jin Wu, Li-Ying Dong, Ying-Jie Zhu, Xianluo Hu
      Abstract: Separators play a pivotal role in the electrochemical performance and safety of lithium-ion batteries (LIBs). The commercial microporous polyolefin-based separators often suffer from inferior electrolyte wettability, low thermal stability, and severe safety concerns. Herein, a novel kind of highly flexible and porous separator based on hydroxyapatite nanowires (HAP NWs) with excellent thermal stability, fire resistance, and superior electrolyte wettability is reported. A hierarchical cross-linked network structure forms between HAP NWs and cellulose fibers (CFs) via hybridization, which endows the separator with high flexibility and robust mechanical strength. The high thermal stability of HAP NW networks enables the separator to preserve its structural integrity at temperatures as high as 700 °C, and the fire-resistant property of HAP NWs ensures high safety of the battery. In particular, benefiting from its unique composition and highly porous structure, the as-prepared HAP/CF separator exhibits near zero contact angle with the liquid electrolyte and high electrolyte uptake of 253%, indicating superior electrolyte wettability compared with the commercial polyolefin separator. The as-prepared HAP/CF separator has unique advantages of superior electrolyte wettability, mechanical robustness, high thermal stability, and fire resistance, thus, is promising as a new kind of separator for advanced LIBs with enhanced performance and high safety.A new kind of highly flexible, porous, high-wettability, fire-resistant hydroxyapatite nanowire-based separator with superior performance and high safety is prepared for advanced lithium-ion batteries. The batteries with the hydroxyapatite nanowire-based separators show better cyclability and enhanced rate capability compared with those with the commercial polypropylene separator. The as-prepared batteries adopting the hydroxyapatite nanowire-based separator can safely work at 150 °C.
      PubDate: 2017-10-16T07:52:06.097151-05:
      DOI: 10.1002/adma.201703548
       
  • Multiscale Humidity Visualization by Environmentally Sensitive Fluorescent
           Molecular Rotors
    • Authors: Yanhua Cheng; Jianguo Wang, Zijie Qiu, Xiaoyan Zheng, Nelson L. C. Leung, Jacky W. Y. Lam, Ben Zhong Tang
      Abstract: Building humidity sensors possessing the features of diverse-configuration compatibility, and capability of measurement of spatial and temporal humidity gradients is of great interest for highly integrated electronics and wearable monitoring systems. Herein, a visual sensing approach based on fluorescent imaging is presented, by assembling aggregation-induced-emission (AIE)-active molecular rotors into a moisture-captured network; the resulting AIE humidity sensors are compatible with diverse applications, having tunable geometries and desirable architectures. The invisible information of relative humidity (RH) is transformed into different fluorescence colors that enable direct observation by the naked eyes based on the twisted intramolecular charge-transfer effect of the AIE-active molecular rotors. The resulting AIE humidity sensors show excellent performance in terms of good sensitivity, precise quantitative measurement, high spatial–temporal resolution, and fast response/recovery time. Their multiscale applications, such as regional environmental RH detection, internal humidity mapping, and sensitive human-body humidity sensing are demonstrated. The proposed humidity visualization strategy may provide a new insight to develop humidity sensors for various applications.Humidity visualization is achieved by incorporating aggregation-induced-emission (AIE)-active molecular rotors into a moisture-capture network. The resulting sensing materials are compatible with diverse configurations for multiple applications, and show excellent performance in terms of good sensitivity, precise quantitative measurement, high spatial–temporal resolution, and fast response/recovery time. This visual strategy provides a new avenue to develop humidity sensors for future high-integrated systems.
      PubDate: 2017-10-16T07:51:02.169756-05:
      DOI: 10.1002/adma.201703900
       
  • Highly Efficient Ternary-Blend Polymer Solar Cells Enabled by a
           Nonfullerene Acceptor and Two Polymer Donors with a Broad Composition
           Tolerance
    • Authors: Xiaopeng Xu; Zhaozhao Bi, Wei Ma, Zishuai Wang, Wallace C. H. Choy, Wenlin Wu, Guangjun Zhang, Ying Li, Qiang Peng
      Abstract: In this work, highly efficient ternary-blend organic solar cells (TB-OSCs) are reported based on a low-bandgap copolymer of PTB7-Th, a medium-bandgap copolymer of PBDB-T, and a wide-bandgap small molecule of SFBRCN. The ternary-blend layer exhibits a good complementary absorption in the range of 300–800 nm, in which PTB7-Th and PBDB-T have excellent miscibility with each other and a desirable phase separation with SFBRCN. In such devices, there exist multiple energy transfer pathways from PBDB-T to PTB7-Th, and from SFBRCN to the above two polymer donors. The hole-back transfer from PTB7-Th to PBDB-T and multiple electron transfers between the acceptor and the donor materials are also observed for elevating the whole device performance. After systematically optimizing the weight ratio of PBDB-T:PTB7-Th:SFBRCN, a champion power conversion efficiency (PCE) of 12.27% is finally achieved with an open-circuit voltage (Voc) of 0.93 V, a short-circuit current density (Jsc) of 17.86 mA cm−2, and a fill factor of 73.9%, which is the highest value for the ternary OSCs reported so far. Importantly, the TB-OSCs exhibit a broad composition tolerance with a high PCE over 10% throughout the whole blend ratios.Highly efficient ternary-blend nonfullerene organic solar cells based on two copolymer donors and one electron acceptor are fabricated and evaluated. The multiple energy and charge-transfer pathways in this ternary system enable the power conversion efficiency to reach 12.27%, which is a new record for ternary-blend organic solar cells at present. These devices also exhibit a broad composition tolerance.
      PubDate: 2017-10-16T07:35:50.222555-05:
      DOI: 10.1002/adma.201704271
       
  • Synthesis of BSA-Coated BiOI@Bi2S3 Semiconductor Heterojunction
           Nanoparticles and Their Applications for Radio/Photodynamic/Photothermal
           Synergistic Therapy of Tumor
    • Authors: Zhao Guo; Shuang Zhu, Yuan Yong, Xiao Zhang, Xinghua Dong, Jiangfeng Du, Jiani Xie, Qing Wang, Zhanjun Gu, Yuliang Zhao
      Abstract: Developing an effective theranostic nanoplatform remains a great challenge for cancer diagnosis and treatment. Here, BiOI@Bi2S3@BSA (bovine serum albumin) semiconductor heterojunction nanoparticles (SHNPs) for triple-combination radio/photodynamic/photothermal cancer therapy and multimodal computed tomography/photoacoustic (CT/PA) bioimaging are reported. On the one hand, SHNPs possess strong X-ray attenuation capability since they contain high-Z elements, and thus they are anticipated to be a very competent candidate as radio-sensitizing materials for radiotherapy enhancement. On the other hand, as a semiconductor, the as-prepared SHNPs offer an extra approach for reactive oxygen species generation based on electron–hole pair under the irradiation of X-ray through the photodynamic therapy process. This X-ray excited photodynamic therapy obviously has better penetration depth in bio-tissue. What's more, the SHNPs also possess well photothermal conversion efficiency for photothermal therapy, because Bi2S3 is a thin band semiconductor with strong near-infrared absorption that can cause local overheat. In vivo tumor ablation studies show that synergistic radio/photodynamic/photothermal therapy achieves more significant therapeutic effect than any single treatment. In addition, with the strong X-ray attenuation and high near-infrared absorption, the as-obtained SHNPs can also be applied as a multimodal contrast agent in CT/PA imaging.A new nanoplatform based on bovine serum albumin coated BiOI@Bi2S3 heterojunction is designed and applied in synergistic radio/photodynamic/photothermal cancer therapy. The high-Z atoms, extra reactive oxygen species generation induced by secondary electrons, and enhanced photothermal effect can achieve efficient tumor ablation. This triple-combination therapy strategy provides better therapeutic outcomes and fewer side effects.
      PubDate: 2017-10-16T07:31:30.015699-05:
      DOI: 10.1002/adma.201704136
       
  • Geometric Design of Scalable Forward Scatterers for Optimally Efficient
           Solar Transformers
    • Authors: Hye-Na Kim; Sanaz Vahidinia, Amanda L. Holt, Alison M. Sweeney, Shu Yang
      Abstract: It will be ideal to deliver equal, optimally efficient “doses” of sunlight to all cells in a photobioreactor system, while simultaneously utilizing the entire solar resource. Backed by the numerical scattering simulation and optimization, here, the design, synthesis, and characterization of the synthetic iridocytes that recapitulated the salient forward-scattering behavior of the Tridacnid clam system are reported, which presents the first geometric solution to allow narrow, precise forward redistribution of flux, utilizing the solar resource at the maximum quantum efficiency possible in living cells. The synthetic iridocytes are composed of silica nanoparticles in microspheres embedded in gelatin, both are low refractive index materials and inexpensive. They show wavelength selectivity, have little loss (the back-scattering intensity is reduced to less than ≈0.01% of the forward-scattered intensity), and narrow forward scattering cone similar to giant clams. Moreover, by comparing experiments and theoretical calculation, it is confirmed that the nonuniformity of the scatter sizes is a “feature not a bug” of the design, allowing for efficient, forward redistribution of solar flux in a micrometer-scaled paradigm. This method is environmentally benign, inexpensive, and scalable to produce optical components that will find uses in efficiency-limited solar conversion technologies, heat sinks, and biofuel production.Synthetic iridocytes composed of hierarchically assembled silica particles and gelatin media are presented to recapitulate the salient forward-scattering behavior of the giant clam system with little loss. The highly forward-scattering system with optimized design of synthetic iridocytes can lead to the first geometric solution to allow efficient, forward redistribution of solar flux in a new micrometer-scaled paradigm.
      PubDate: 2017-10-16T06:32:23.343091-05:
      DOI: 10.1002/adma.201702922
       
  • Flexible Aqueous Li-Ion Battery with High Energy and Power Densities
    • Authors: Chongyin Yang; Xiao Ji, Xiulin Fan, Tao Gao, Liumin Suo, Fei Wang, Wei Sun, Ji Chen, Long Chen, Fudong Han, Ling Miao, Kang Xu, Konstantinos Gerasopoulos, Chunsheng Wang
      Abstract: A flexible and wearable aqueous symmetrical lithium-ion battery is developed using a single LiVPO4F material as both cathode and anode in a “water-in-salt” gel polymer electrolyte. The symmetric lithium-ion chemistry exhibits high energy and power density and long cycle life, due to the formation of a robust solid electrolyte interphase consisting of Li2CO3-LiF, which enables fast Li-ion transport. Energy densities of 141 Wh kg−1, power densities of 20 600 W kg−1, and output voltage of 2.4 V can be delivered during>4000 cycles, which is far superior to reported aqueous energy storage devices at the same power level. Moreover, the full cell shows unprecedented tolerance to mechanical stress such as bending and cutting, where it not only does not catastrophically fail, as most nonaqueous cells would, but also maintains cell performance and continues to operate in ambient environment, a unique feature apparently derived from the high stability of the “water-in-salt” gel polymer electrolyte.A flexible and wearable aqueous lithium-ion battery is introduced based on a unique “water-in-salt” gel polymer electrolyte and single electrode material with far superior energy density to reported aqueous energy storage devices at the same power level. The full cell can operate in open air, exhibiting ambient insensitivity, high safety, and unprecedented tolerance to against mechanical stress.
      PubDate: 2017-10-16T00:31:02.890905-05:
      DOI: 10.1002/adma.201701972
       
  • Graphene-Based Linear Tandem Micro-Supercapacitors with Metal-Free Current
           Collectors and High-Voltage Output
    • Authors: Xiaoyu Shi; Zhong-Shuai Wu, Jieqiong Qin, Shuanghao Zheng, Sen Wang, Feng Zhou, Chenglin Sun, Xinhe Bao
      Abstract: Printable supercapacitors are regarded as a promising class of microscale power source, but are facing challenges derived from conventional sandwich-like geometry. Herein, the printable fabrication of new-type planar graphene-based linear tandem micro-supercapacitors (LTMSs) on diverse substrates with symmetric and asymmetric configuration, high-voltage output, tailored capacitance, and outstanding flexibility is demonstrated. The resulting graphene-based LTMSs consisting of 10 micro-supercapacitors (MSs) present efficient high-voltage output of 8.0 V, suggestive of superior uniformity of the entire integrated device. Meanwhile, LTMSs possess remarkable flexibility without obvious capacitance degradation under different bending states. Moreover, areal capacitance of LTMSs can be sufficiently modulated by incorporating polyaniline-based pseudocapacitive nanosheets into graphene electrodes, showing enhanced capacitance of 7.6 mF cm−2. To further improve the voltage output and energy density, asymmetric LTMSs are fabricated through controlled printing of linear-patterned graphene as negative electrodes and MnO2 nanosheets as positive electrodes. Notably, the asymmetric LTMSs from three serially connected MSs are easily extended to 5.4 V, triple voltage output of the single cell (1.8 V), suggestive of the versatile applicability of this technique. Therefore, this work offers numerous opportunities of graphene and analogous nanosheets for one-step scalable fabrication of flexible tandem energy storage devices integrating with printed electronics on same substrate.A universal printing technology is demonstrated to fabricate graphene-based linear tandem micro-supercapacitors, with tailored planar device geometry and metal-free current collectors and interconnects, on different substrates. The fabricated devices show high-voltage output, remarkable flexibility, and outstanding electrochemical performance due to the advanced device geometry and high-performance 2D nanosheets.
      PubDate: 2017-10-13T07:27:38.674945-05:
      DOI: 10.1002/adma.201703034
       
  • 2D Ruddlesden–Popper Perovskites for Optoelectronics
    • Authors: Yani Chen; Yong Sun, Jiajun Peng, Junhui Tang, Kaibo Zheng, Ziqi Liang
      Abstract: Conventional 3D organic–inorganic halide perovskites have recently undergone unprecedented rapid development. Yet, their inherent instabilities over moisture, light, and heat remain a crucial challenge prior to the realization of commercialization. By contrast, the emerging 2D Ruddlesden−Popper-type perovskites have recently attracted increasing attention owing to their great environmental stability. However, the research of 2D perovskites is just in their infancy. In comparison to 3D analogues, they are natural quantum wells with a much larger exciton binding energy. Moreover, their inner structural, dielectric, optical, and excitonic properties remain to be largely explored, limiting further applications. This review begins with an introduction to 2D perovskites, along with a detailed comparison to 3D counterparts. Then, a discussion of the organic spacer cation engineering of 2D perovskites is presented. Next, quasi-2D perovskites that fall between 3D and 2D perovskites are reviewed and compared. The unique excitonic properties, electron–phonon coupling, and polarons of 2D perovskites are then be revealed. A range of their (opto)electronic applications is highlighted in each section. Finally, a summary is given, and the strategies toward structural design, growth control, and photophysics studies of 2D perovskites for high-performance electronic devices are rationalized.Recent advances in 2D organometal halide perovskites are reviewed. A comprehensive comparison between 3D and 2D perovskites is provided, including crystal structure and orientation, transport dynamics, and optoelectronic performance. Among them, organic spacer engineering and modulating physical properties of 2D perovskites are highlighted. Finally, future developments and possible strategies to the unsolved challenges are outlined.
      PubDate: 2017-10-13T07:27:01.944612-05:
      DOI: 10.1002/adma.201703487
       
  • Adsorbed Eutectic GaIn Structures on a Neoprene Foam for Stretchable MRI
           Coils
    • Authors: Matija Varga; Andreas Mehmann, Josip Marjanovic, Jonas Reber, Christian Vogt, Klaas Paul Pruessmann, Gerhard Tröster
      Abstract: Stretchable conductors based on eutectic gallium–indium (eGaIn) alloy are patterned on a polychloroprene substrate (neoprene foam) using stencil printing. By tuning the amount of eGaIn on the neoprene substrate, different strain-sensitivity of electrical resistance is achieved. Conductors with a layer of eGaIn, which adsorbs to the walls of 60–100 µm wide neoprene cells, change their electrical resistance for 5% at 100% strain. When the amount of eGaIn is increased, the cells are filled with eGaIn and the strain-sensitivity of the electrical resistance rises to 300% at 100% strain. The developed conductors are patterned as stretchable on-body coils for receiving magnetic signals in a clinical magnetic resonance imaging setup. First images with a stretchable coil are acquired on an orange and compared to the images that are recorded using a rigid copper coil of the same size.Stretchable conductors based on eutectic gallium–indium (eGaIn) alloy are fabricated on a substrate with a microstructured surface (neoprene foam). By varying the amount of the eGaIn alloy during stencil-printing, the strain sensitivity of electrical resistance is tuned from 5% to 300% at 100% strain. The developed conductors are used to fabricate stretchable on-body coils for magnetic resonance imaging.
      PubDate: 2017-10-13T07:23:12.71465-05:0
      DOI: 10.1002/adma.201703744
       
  • Engineering Cell Surface Function with DNA Origami
    • Authors: Ehsan Akbari; Molly Y. Mollica, Christopher R. Lucas, Sarah M. Bushman, Randy A. Patton, Melika Shahhosseini, Jonathan W. Song, Carlos E. Castro
      Abstract: A specific and reversible method is reported to engineer cell-membrane function by embedding DNA-origami nanodevices onto the cell surface. Robust membrane functionalization across epithelial, mesenchymal, and nonadherent immune cells is achieved with DNA nanoplatforms that enable functions including the construction of higher-order DNA assemblies at the cell surface and programed cell–cell adhesion between homotypic and heterotypic cells via sequence-specific DNA hybridization. It is anticipated that integration of DNA-origami nanodevices can transform the cell membrane into an engineered material that can mimic, manipulate, and measure biophysical and biochemical function within the plasma membrane of living cells.Cell membranes are engineered by embedding DNA-origami nanodevices onto the surface of live cells. Functionalities including programmed homotypic and heterotypic cell–cell adhesion via sequence-specific DNA hybridization are demonstrated. Embedding DNA-origami nanodevices onto the cell membrane provides a foundation to mimic, control, and monitor biological processes and interactions in local cell environments.
      PubDate: 2017-10-13T07:21:31.110437-05:
      DOI: 10.1002/adma.201703632
       
  • High-Performance Inorganic Perovskite Quantum Dot–Organic Semiconductor
           Hybrid Phototransistors
    • Authors: Yantao Chen; Yingli Chu, Xiaohan Wu, Wei Ou-Yang, Jia Huang
      Abstract: All-inorganic lead halide perovskite quantum dots (IHP QDs) have great potentials in photodetectors. However, the photoresponsivity is limited by the low charge transport efficiency of the IHP QD layers. High-performance phototransistors based on IHP QDs hybridized with organic semiconductors (OSCs) are developed. The smooth surface of IHP QD layers ensures ordered packing of the OSC molecules above them. The OSCs significantly improve the transportation of the photoexcited charges, and the gate effect of the transistor structure significantly enhances the photoresponsivity while simultaneously maintaining high Iphoto/Idark ratio. The devices exhibit outstanding optoelectronic properties in terms of photoresponsivity (1.7 × 104 A W−1), detectivity (2.0 × 1014 Jones), external quantum efficiency (67000%), Iphoto/Idark ratio (8.1 × 104), and stability (100 d in air). The overall performances of our devices are superior to state-of-the-art IHP photodetectors. The strategy utilized here is general and can be easily applied to many other perovskite photodetectors.High-performance hybrid phototransistors based on all-inorganic lead halide perovskite quantum dots and organic semiconductors are fabricated and characterized. Because of the outstanding properties of materials, the gate-tunable phototransistors exhibit significantly high performance, including photoresponsivity (≈1.7 × 104 A W−1), detectivity (≈2.0 × 1014 Jones), EQE (≈67000%), Iphoto/Idark ratio (≈8.1 × 104), and long-term stability in air.
      PubDate: 2017-10-13T07:20:48.430425-05:
      DOI: 10.1002/adma.201704062
       
  • 2D Organic Materials for Optoelectronic Applications
    • Authors: Fangxu Yang; Shanshan Cheng, Xiaotao Zhang, Xiaochen Ren, Rongjin Li, Huanli Dong, Wenping Hu
      Abstract: The remarkable merits of 2D materials with atomically thin structures and optoelectronic attributes have inspired great interest in integrating 2D materials into electronics and optoelectronics. Moreover, as an emerging field in the 2D-materials family, assembly of organic nanostructures into 2D forms offers the advantages of molecular diversity, intrinsic flexibility, ease of processing, light weight, and so on, providing an exciting prospect for optoelectronic applications. Herein, the applications of organic 2D materials for optoelectronic devices are a main focus. Material examples include 2D, organic, crystalline, small molecules, polymers, self-assembly monolayers, and covalent organic frameworks. The protocols for 2D-organic-crystal-fabrication and -patterning techniques are briefly discussed, then applications in optoelectronic devices are introduced in detail. Overall, an introduction to what is known and suggestions for the potential of many exciting developments are presented.Assembling organic nanostructures into 2D form offers the advantages of molecular diversity, flexibility, and unique physical properties, providing exciting future prospects for optoelectronic applications. This review focuses on the applications of organic 2D materials for optoelectronic devices. After a brief discussion on the protocols for 2D crystal fabrication and patterning techniques, their applications in optoelectronic devices are introduced and an outlook is provided.
      PubDate: 2017-10-12T14:30:50.944937-05:
      DOI: 10.1002/adma.201702415
       
  • The Electrical and Optical Properties of Organometal Halide Perovskites
           Relevant to Optoelectronic Performance
    • Authors: Valerio Adinolfi; Wei Peng, Grant Walters, Osman M. Bakr, Edward H. Sargent
      Abstract: Organometal halide perovskites are under intense study for use in optoelectronics. Methylammonium and formamidinium lead iodide show impressive performance as photovoltaic materials; a premise that has spurred investigations into light-emitting devices and photodetectors. Herein, the optical and electrical material properties of organometal halide perovskites are reviewed. An overview is given on how the material composition and morphology are tied to these properties, and how these properties ultimately affect device performance. Material attributes and techniques used to estimate them are analyzed for different perovskite materials, with a particular focus on the bandgap, mobility, diffusion length, carrier lifetime, and trap-state density.Organometal halide perovskites offer promise as high-performance solution-processed optoelectronic materials. Herein, the optical and electrical properties of these materials are reviewed, as well as how these relate to material aspects and their influence on device performance.
      PubDate: 2017-10-12T14:29:32.776974-05:
      DOI: 10.1002/adma.201700764
       
  • Electronic-Reconstruction-Enhancedis-Tunneling Conductance at Terrace
           Edges of Ultrathin Oxide Films
    • Authors: Lingfei Wang; Rokyeon Kim, Yoonkoo Kim, Choong H. Kim, Sangwoon Hwang, Myung Rae Cho, Yeong Jae Shin, Saikat Das, Jeong Rae Kim, Sergei V. Kalinin, Miyoung Kim, Sang Mo Yang, Tae Won Noh
      Abstract: Quantum mechanical tunneling of electrons across ultrathin insulating oxide barriers has been studied extensively for decades due to its great potential in electronic-device applications. In the few-nanometers-thick epitaxial oxide films, atomic-scale structural imperfections, such as the ubiquitously existed one-unit-cell-high terrace edges, can dramatically affect the tunneling probability and device performance. However, the underlying physics has not been investigated adequately. Here, taking ultrathin BaTiO3 films as a model system, an intrinsic tunneling-conductance enhancement is reported near the terrace edges. Scanning-probe-microscopy results demonstrate the existence of highly conductive regions (tens of nanometers wide) near the terrace edges. First-principles calculations suggest that the terrace-edge geometry can trigger an electronic reconstruction, which reduces the effective tunneling barrier width locally. Furthermore, such tunneling-conductance enhancement can be discovered in other transition metal oxides and controlled by surface-termination engineering. The controllable electronic reconstruction can facilitate the implementation of oxide electronic devices and discovery of exotic low-dimensional quantum phases.Intrinsic tunneling-conductance enhancement is discovered near the terrace edges of ultrathin BaTiO3 films. The terrace-edge geometry can trigger an electronic reconstruction, which reduces the effective-tunneling-barrier width locally. Such tunneling-conductance enhancement can be found in other transition metal oxides and is controlled by surface termination engineering.
      PubDate: 2017-10-12T14:29:09.466996-05:
      DOI: 10.1002/adma.201702001
       
  • Metal-Halide Perovskite Transistors for Printed Electronics: Challenges
           and Opportunities
    • Authors: Yen-Hung Lin; Pichaya Pattanasattayavong, Thomas D. Anthopoulos
      Abstract: Following the unprecedented rise in photovoltaic power conversion efficiencies during the past five years, metal-halide perovskites (MHPs) have emerged as a new and highly promising class of solar-energy materials. Their extraordinary electrical and optical properties combined with the abundance of the raw materials, the simplicity of synthetic routes, and processing versatility make MHPs ideal for cost-efficient, large-volume manufacturing of a plethora of optoelectronic devices that span far beyond photovoltaics. Herein looks beyond current applications in the field of energy, to the area of large-area electronics using MHPs as the semiconductor material. A comprehensive overview of the relevant fundamental material properties of MHPs, including crystal structure, electronic states, and charge transport, is provided first. Thereafter, recent demonstrations of MHP-based thin-film transistors and their application in logic circuits, as well as bi-functional devices such as light-sensing and light-emitting transistors, are discussed. Finally, the challenges and opportunities in the area of MHPs-based electronics, with particular emphasis on manufacturing, stability, and health and environmental concerns, are highlighted.Their extraordinary electrical and optical properties combined with the abundance of their raw materials, have driven metal-halide perovskites (MHPs) to the forefront of functional electronic materials research, with envisioned applications spanning across several technology sectors. Herein, the recent advances in the use of MHPs in the area of transistors and transistor-related applications are summarized.
      PubDate: 2017-10-12T14:24:07.810845-05:
      DOI: 10.1002/adma.201702838
       
  • 3D Porous Hydrogel/Conducting Polymer Heterogeneous Membranes with
           Electro-/pH-Modulated Ionic Rectification
    • Authors: Bin Bao; Junran Hao, Xiujie Bian, Xuanbo Zhu, Kai Xiao, Jingwen Liao, Jiajia Zhou, Yahong Zhou, Lei Jiang
      Abstract: Heterogeneous membranes composed of asymmetric structures or compositions have enormous potential in sensors, molecular sieves, and energy devices due to their unique ion transport properties such as ionic current rectification and ion selectivity. So far, heterogeneous membranes with 1D nanopores have been extensively studied. However, asymmetric structures with 3D micro-/nanoscale pore networks have never been investigated. Here, a simple and versatile approach to low-costly fabricate hydrogel/conducting polymer asymmetric heterogeneous membranes with electro-/pH-responsive 3D micro-/nanoscale ion channels is introduced. Due to the asymmetric heterojunctions between positively charged nanoporous polypyrrole (PPy) and negatively charged microscale porous hydrogel poly (acrylamide-co-acrylic acid) (P(AAm-co-AA)), the membrane can rectify ion transmembrane transport in response to both electro- and pH-stimuli. Numerical simulations based on coupled Poisson and Nernst–Plank equations are carried out to explain the ionic rectification mechanisms for the membranes. The membranes are not dependent on elaborately fabricated 1D ion channel substrates and hence can be facilely prepared in a low-cost and large-area way. The hybridization of hydrogel and conducting polymer offers a novel strategy for constructing low-cost, large-area and multifunctional membranes, expanding the tunable ionic rectification properties into macroscopic membranes with micro-/nanoscale pores, which would stimulate practical applications of the membranes.3D porous hydrogel/conducting polymer heterogeneous membranes with electro-/pH-modulated ionic rectification have been fabricated by electrochemically depositing nanoporous conducting polymer polypyrrole onto a hydrogel polyacrylamide-polyacrylic acid substrate. The facilely prepared heterogenous membranes with 3D interconnected channels would find numerous applications in sensors, biomolecular sieves, and energy conversion devices.
      PubDate: 2017-10-12T14:23:45.914259-05:
      DOI: 10.1002/adma.201702926
       
  • An All-Integrated Anode via Interlinked Chemical Bonding between
           Double-Shelled–Yolk-Structured Silicon and Binder for Lithium-Ion
           Batteries
    • Authors: Yajie Liu; Zhixin Tai, Tengfei Zhou, Vitor Sencadas, Jian Zhang, Lei Zhang, Konstantin Konstantinov, Zaiping Guo, Hua Kun Liu
      Abstract: The concept of an all-integrated design with multifunctionalization is widely employed in optoelectronic devices, sensors, resonator systems, and microfluidic devices, resulting in benefits for many ongoing research projects. Here, maintaining structural/electrode stability against large volume change by means of an all-integrated design is realized for silicon anodes. An all-integrated silicon anode is achieved via multicomponent interlinking among carbon@void@silica@silicon (CVSS) nanospheres and cross-linked carboxymethyl cellulose and citric acid polymer binder (c-CMC-CA). Due to the additional protection from the silica layer, CVSS is superior to the carbon@void@silicon (CVS) electrode in terms of long-term cyclability. The as-prepared all-integrated CVSS electrode exhibits high mechanical strength, which can be ascribed to the high adhesivity and ductility of c-CMC-CA binder and the strong binding energy between CVSS and c-CMC-CA, as calculated based on density functional theory (DFT). This electrode exhibits a high reversible capacity of 1640 mA h g−1 after 100 cycles at a current density of 1 A g−1, high rate performance, and long-term cycling stability with 84.6% capacity retention after 1000 cycles at 5 A g−1.An all-integrated anode design via multicomponent chemical interlinking among carbon@void@silica@silicon (CVSS) nanospheres and cross-linked carboxymethyl cellulose and citric acid polymer binder (c-CMC-CA) is developed for achieving electrode/structural stability of a silicon anode during lithiation/delithiation. The obtained excellent electrochemical performance can be ascribed to the collaboration of the double-shelled–yolk-structured silicon and the covalent-interlinked high-strength binder system.
      PubDate: 2017-10-12T14:23:26.070672-05:
      DOI: 10.1002/adma.201703028
       
  • Bioinspired Dynamic Wetting on Multiple Fibers
    • Authors: Pengwei Wang; Ruixin Bian, Qing'an Meng, Huan Liu, Lei Jiang
      Abstract: Natural fibers have versatile strategies for interacting with water media and better adapting to the local environment, and these strategies offer inspiration for the development of artificial functional fibers with diverse applications. Wetting on fibers is a dynamic liquid-moving process on/in fibrous systems with various patterns, and the process is normally driven by the structural gradient, chemical gradient, elasticity of a single fiber, or the synergistic effect of these factors in multiple fibers in an integrated system in which the spatial geometry of the fibers is involved. Compared with the directional liquid movement on a single fiber, wetting on multiple fibers in both the micro- and macroscales is particularly fascinating, with various performances, including directional liquid transport, controllable liquid transfer, efficient liquid encapsulation, and capillary-induced fibrous coalescence. Based on these properties, fibrous materials offer an alternative open system for liquid manipulation that is applicable to various functional liquid materials. Here, recent achievements in bioinspired dynamic wetting on multiple fibers are highlighted, and perspectives on future directions are presented.Recent research progress in bioinspired dynamic wetting on multiple fibers is summarized, and the distinctive wetting behaviors of five types of natural fibrous systems, including water strider legs, a shorebird beak, a Chinese brush, dandelion pappi, and wet hairs, are presented, along with related bioinspired systems. Meanwhile, perspectives on the research trends in the wetting of multiple fibers are discussed.
      PubDate: 2017-10-12T14:22:49.802725-05:
      DOI: 10.1002/adma.201703042
       
  • Superlyophilic Interfaces and Their Applications
    • Authors: Zhongpeng Zhu; Shuang Zheng, Shan Peng, Yong Zhao, Ye Tian
      Abstract: Superlyophilic interfaces denote interfaces displaying strong affinity to diverse liquids, including superhydrophilic, superoleophilic, and superamphiphilic interfaces. When coming in contact with these interfaces, water or oil droplets tend to spread completely with contact angles close to 0°, presenting versatile applications including self-cleaning, antifogging, controllable liquid transport, liquid separation, and so forth. Inspired by nature, scientists have developed various kinds of artificial superlyophilic (SLPL) interfaces in the past decades. In terms of dimensional characteristics, the artificial SLPL interfaces can be divided into four categories: i) 0D particles, whose dispersibility or catalytic performance can be notably enhanced by superlyophilicity; ii) 1D micro-/nanofibers or nanotubes/channels, which can efficiently transfer liquids with SLPL interfaces; iii) 2D flat SLPL interfaces, on which different functional molecules can be deposited uniformly, forming ultrathin and smooth films; and iv) 3D structures, which can be obtained by either constructing 0D, 1D, or 2D SLPL materials separately or directly fabricating random SLPL frameworks, and can always be used as functional coatings or bulk materials. Here, natural and artificial SLPL interfaces are briefly introduced, followed by a short discussion of the limit between lyophilicity and lyophobicity, and then a snapshot of methods to generate SLPL interfaces is given. Specific focus is placed on recent achievements of constructing SLPL interfaces from zero to three dimensions. Following that, broad applications of SLPL interfaces in commercial areas will be introduced. Finally, a short summary and outlook for future challenges in this field is presented.Recent progress regarding superlyophilic interfaces with different dimensions is reviewed, including 0D particles, 1D fibers or tubes, 2D flat interfaces, and 3D materials. Moreover, the broad applications of superlyophilic interfaces are described, spanning from conductivity enhancement and self-cleaning, liquid transport, and antifogging, to printing and liquid separation, heat transfer, and film fabrication.
      PubDate: 2017-10-12T14:22:07.103302-05:
      DOI: 10.1002/adma.201703120
       
  • 4D Biofabrication Using Shape-Morphing Hydrogels
    • Authors: Alina Kirillova; Ridge Maxson, Georgi Stoychev, Cheryl T. Gomillion, Leonid Ionov
      Abstract: Despite the tremendous potential of bioprinting techniques toward the fabrication of highly complex biological structures and the flourishing progress in 3D bioprinting, the most critical challenge of the current approaches is the printing of hollow tubular structures. In this work, an advanced 4D biofabrication approach, based on printing of shape-morphing biopolymer hydrogels, is developed for the fabrication of hollow self-folding tubes with unprecedented control over their diameters and architectures at high resolution. The versatility of the approach is demonstrated by employing two different biopolymers (alginate and hyaluronic acid) and mouse bone marrow stromal cells. Harnessing the printing and postprinting parameters allows attaining average internal tube diameters as low as 20 µm, which is not yet achievable by other existing bioprinting/biofabrication approaches and is comparable to the diameters of the smallest blood vessels. The proposed 4D biofabrication process does not pose any negative effect on the viability of the printed cells, and the self-folded hydrogel-based tubes support cell survival for at least 7 d without any decrease in cell viability. Consequently, the presented 4D biofabrication strategy allows the production of dynamically reconfigurable architectures with tunable functionality and responsiveness, governed by the selection of suitable materials and cells.An advanced 4D biofabrication approach, based on shape-morphing biopolymer hydrogels, is presented for the fabrication of hollow self-folding tubes with unprecedented control over their diameters and architectures at high resolution. The approach paves new avenues for the creation of tailored cell-laden shape-morphing architectures for tissue engineering and regenerative medicine applications.
      PubDate: 2017-10-12T14:21:35.402451-05:
      DOI: 10.1002/adma.201703443
       
  • Structurally Deformed MoS2 for Electrochemically Stable, Thermally
           Resistant, and Highly Efficient Hydrogen Evolution Reaction
    • Authors: Yen-Chang Chen; Ang-Yu Lu, Ping Lu, Xiulin Yang, Chang-Ming Jiang, Marina Mariano, Brian Kaehr, Oliver Lin, André Taylor, Ian D. Sharp, Lain-Jong Li, Stanley S. Chou, Vincent Tung
      Abstract: The emerging molybdenum disulfide (MoS2) offers intriguing possibilities for realizing a transformative new catalyst for driving the hydrogen evolution reaction (HER). However, the trade-off between catalytic activity and long-term stability represents a formidable challenge and has not been extensively addressed. This study reports that metastable and temperature-sensitive chemically exfoliated MoS2 (ce-MoS2) can be made into electrochemically stable (5000 cycles), and thermally robust (300 °C) while maintaining synthetic scalability and excellent catalytic activity through physical-transformation into 3D structurally deformed nanostructures. The dimensional transition enabled by a high throughput electrohydrodynamic process provides highly accessible, and electrochemically active surface area and facilitates efficient transport across various interfaces. Meanwhile, the hierarchically strained morphology is found to improve electronic coupling between active sites and current collecting substrates without the need for selective engineering the electronically heterogeneous interfaces. Specifically, the synergistic combination of high strain load stemmed from capillarity-induced-self-crumpling and sulfur (S) vacancies intrinsic to chemical exfoliation enables simultaneous modulation of active site density and intrinsic HER activity regardless of continuous operation or elevated temperature. These results provide new insights into how catalytic activity, electrochemical-, and thermal stability can be concurrently enhanced through the physical transformation that is reminiscent of nature, in which properties of biological materials emerge from evolved dimensional transitions.Bioinspired dimensional transition of MoS2 enables the modulation of catalytic property and drastically improves the long-term operational stability while preserving the synthetic scalability. The experimental demonstration provides elegant insights into how physical transformation can be leveraged to direct energetics of electrochemical processes.
      PubDate: 2017-10-12T14:21:12.47999-05:0
      DOI: 10.1002/adma.201703863
       
  • Hollow Co3O4 Nanosphere Embedded in Carbon Arrays for Stable and Flexible
           Solid-State Zinc–Air Batteries
    • Authors: Cao Guan; Afriyanti Sumboja, Haijun Wu, Weina Ren, Ximeng Liu, Hong Zhang, Zhaolin Liu, Chuanwei Cheng, Stephen J. Pennycook, John Wang
      Abstract: Highly active and durable air cathodes to catalyze both the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are urgently required for rechargeable metal–air batteries. In this work, an efficient bifunctional oxygen catalyst comprising hollow Co3O4 nanospheres embedded in nitrogen-doped carbon nanowall arrays on flexible carbon cloth (NC-Co3O4/CC) is reported. The hierarchical structure is facilely derived from a metal–organic framework precursor. A carbon onion coating constrains the Kirkendall effect to promote the conversion of the Co nanoparticles into irregular hollow oxide nanospheres with a fine scale nanograin structure, which enables promising catalytic properties toward both OER and ORR. The integrated NC-Co3O4/CC can be used as an additive-free air cathode for flexible all-solid-state zinc–air batteries, which present high open circuit potential (1.44 V), high capacity (387.2 mAh g−1, based on the total mass of Zn and catalysts), excellent cycling stability and mechanical flexibility, significantly outperforming Pt- and Ir-based zinc–air batteries.An efficient bifunctional oxygen catalyst comprising hollow Co3O4 nanospheres embedded in N-doped carbon nanowall arrays (NC-Co3O4) is facilely fabricated from a metal–organic framework. The additive-free NC-Co3O4 electrode can be directly utilized as an efficient air cathode for a flexible solid-state Zn–air battery, which demonstrates much improved cycling stability and mechanical flexibility than Pt- and Ir-based zinc–air batteries.
      PubDate: 2017-10-12T14:20:25.63619-05:0
      DOI: 10.1002/adma.201704117
       
  • Chemical Patterning of High-Mobility Semiconducting 2D Bi2O2Se Crystals
           for Integrated Optoelectronic Devices
    • Authors: Jinxiong Wu; Yujing Liu, Zhenjun Tan, Congwei Tan, Jianbo Yin, Tianran Li, Teng Tu, Hailin Peng
      Abstract: Patterning of high-mobility 2D semiconducting materials with unique layered structures and superb electronic properties offers great potential for batch fabrication and integration of next-generation electronic and optoelectronic devices. Here, a facile approach is used to achieve accurate patterning of 2D high-mobility semiconducting Bi2O2Se crystals using dilute H2O2 and protonic mixture acid as efficient etchants. The 2D Bi2O2Se crystal after chemical etching maintains a high Hall mobility of over 200 cm2 V−1 s−1 at room temperature. Centimeter-scale well-ordered arrays of 2D Bi2O2Se with tailorable configurations are readily obtained. Furthermore, integrated photodetectors based on 2D Bi2O2Se arrays are fabricated, exhibiting excellent air stability and high photoresponsivity of ≈2000 A W−1 at 532 nm. These results are one step towards the practical application of ultrathin 2D integrated digital and optoelectronic circuits.Controlled patterning of high-mobility semiconducting two-dimensional Bi2O2Se crystals was achieved by a facile wet-chemical etching approach using diluted H2O2/protonic acid etchants. Centimeter-scale well-ordered two-dimensional Bi2O2Se arrays exhibit a high Hall mobility of over 200 cm2 V−1 s−1 at room temperature, and are integrated into air-stable photodetectors with an ultrahigh photoresponsivity of ≈2000 A W−1 at 532 nm.
      PubDate: 2017-10-12T14:18:50.773688-05:
      DOI: 10.1002/adma.201704060
       
  • Photocatalyzing CO2 to CO for Enhanced Cancer Therapy
    • Authors: Di-Wei Zheng; Bin Li, Chu-Xin Li, Lu Xu, Jin-Xuan Fan, Qi Lei, Xian-Zheng Zhang
      Abstract: Continuous exposure to carbon monoxide (CO) can sensitize cancer cells to chemotherapy while protect normal cells from apoptosis. The Janus face of CO thus provides an ideal strategy for cancer therapy. Here, a photocatalytic nanomaterial (HisAgCCN) is introduced to transform endogenous CO2 to CO for improving cancer therapy in vivo. The CO production rate of HisAgCCN reaches to 65 µmol h−1 gmat−1, which can significantly increase the cytotoxicity of anticancer drug (doxorubicin, DOX) by 70%. Interestingly, this study finds that HisAgCCN can enhance mitochondria biogenesis and aggravate oxidative stress in cancer cells, whereas protect normal cells from chemotherapy-induced apoptosis as well. Proteomics and metabolomics studies reveal that HisAgCCN can enhance mitochondria biogenesis and aggravate oxidative stress in cancer cells specifically. In vivo studies indicate that HisAgCCN/DOX combination therapy presents a synergetic tumor inhibition, which might provide a new direction for clinical cancer therapy.A photocatalytic nanomaterial (HisAgCCN) transforming endogenous CO2 to CO is synthesized for improving cancer chemotherapy in vivo. CO produced through photocatalysis can enhance mitochondria biogenesis and aggravate oxidative stress in cancer cells, whereas protect normal cells from chemotherapy-induced apoptosis as well. HisAgCCN/DOX combination therapy may provide a new direction for cancer therapy.
      PubDate: 2017-10-11T06:59:06.649099-05:
      DOI: 10.1002/adma.201703822
       
  • Guided Molecular Assembly on a Locally Reactive 2D Material
    • Authors: Ben Warner; Tobias G. Gill, Vasile Caciuc, Nicolae Atodiresei, Antoine Fleurence, Yasuo Yoshida, Yukio Hasegawa, Stefan Blügel, Yukiko Yamada-Takamura, Cyrus F. Hirjibehedin
      Abstract: Atomically precise engineering of the position of molecular adsorbates on surfaces of 2D materials is key to their development in applications ranging from catalysis to single-molecule spintronics. Here, stable room-temperature templating of individual molecules with localized electronic states on the surface of a locally reactive 2D material, silicene grown on ZrB2, is demonstrated. Using a combination of scanning tunneling microscopy and density functional theory, it is shown that the binding of iron phthalocyanine (FePc) molecules is mediated via the strong chemisorption of the central Fe atom to the sp3-like dangling bond of Si atoms in the linear silicene domain boundaries. Since the planar Pc ligand couples to the Fe atom mostly through the in-plane d orbitals, localized electronic states resembling those of the free molecule can be resolved. Furthermore, rotation of the molecule is restrained because of charge rearrangement induced by the bonding. These results highlight how nanoscale changes can induce reactivity in 2D materials, which can provide unique surface interactions for enabling novel forms of guided molecular assembly.Molecular templating using a locally reactive 2D material is achieved at the domain boundaries of silicene formed on ZrB2. Selective bonding between silicene sp3-like states and the dz2 orbitals of iron phthalocyanine (FePc) molecules preserves electronic states that are strongly localized on the Pc ligand while pinning the molecule into a unique rotational alignment up to room temperature.
      PubDate: 2017-10-11T06:58:14.514828-05:
      DOI: 10.1002/adma.201703929
       
  • Nanoparticle Regrowth Enhances Photoacoustic Signals of Semiconducting
           Macromolecular Probe for In Vivo Imaging
    • Authors: Chen Xie; Xu Zhen, Yan Lyu, Kanyi Pu
      Abstract: Smart molecular probes that emit deep-tissue penetrating photoacoustic (PA) signals responsive to the target of interest are imperative to understand disease pathology and develop innovative therapeutics. This study reports a self-assembly approach to develop semiconducting macromolecular activatable probe for in vivo imaging of reactive oxygen species (ROS). This probe comprises a near-infrared absorbing phthalocyanine core and four poly(ethylene glycol) (PEG) arms linked by ROS-responsive self-immolative segments. Such an amphiphilic macromolecular structure allows it to undergo an ROS-specific cleavage process to release hydrophilic PEG and enhance the hydrophobicity of the nanosystem. Consequently, the residual phthalocyanine component self-assembles and regrows into large nanoparticles, leading to ROS-enhanced PA signals. The small size of the intact macromolecular probe is beneficial to penetrate into the tumor tissue of living mice, while the ROS-activated regrowth of nanoparticles prolongs the retention along with enhanced PA signals, permitting imaging of ROS during chemotherapy. This study thus capitalizes on stimuli-controlled self-assembly of macromolecules in conjunction with enhanced heat transfer in large nanoparticles for the development of smart molecular probes for PA imaging.A semiconducting macromolecular probe (PCBP) that can self-assemble into large nanoparticles in the presence of reactive oxygen species (ROS) is synthesized for photoacoustic (PA) molecular imaging. The small size and intact nanostructure of PCBP permit passively target the tumor, while the ROS-activated regrowth of nanoparticles prolongs the retention and enhances the PA signals in the tumor site.
      PubDate: 2017-10-11T06:57:21.358918-05:
      DOI: 10.1002/adma.201703693
       
  • Therapeutic-Gas-Responsive Hydrogel
    • Authors: Junghong Park; Swapan Pramanick, Dongsik Park, Jiwon Yeo, Jihyun Lee, Haeshin Lee, Won Jong Kim
      Abstract: Nitric oxide (NO) is a crucial signaling molecule with various functions in physiological systems. Due to its potent biological effect, the preparation of responsive biomaterials upon NO having temporally transient properties is a challenging task. This study represents the first therapeutic-gas (i.e., NO)-responsive hydrogel by incorporating a NO-cleavable crosslinker. The hydrogel is rapidly swollen in response to NO, and not to other gases. Furthermore, the NO-responsive gel is converted to enzyme-responsive gels by cascade reactions from an enzyme to NO production for which the NO precursor is a substrate of the enzyme. The application of the hydrogel as a NO-responsive drug-delivery system is proved here by revealing effective protein drug release by NO infusion, and the hydrogel is also shown to be swollen by the NO secreted from the cultured cells. The NO-responsive hydrogel may prove useful in many applications, for example drug-delivery vehicles, inflammation modulators, and as a tissue scaffold.A nitric oxide (NO)-responsive hydrogel is rapidly swollen in response to transient NO and not to other gases by cleavage of a NO-cleavable crosslinker. The hydrogel shows high selectivity and sensitivity to various phases of NO, including the gaseous and solution states, freshly released NO from a solid NO donor, or NO secreted from cultured cells.
      PubDate: 2017-10-11T01:30:03.263336-05:
      DOI: 10.1002/adma.201702859
       
  • Superaligned Carbon Nanotubes Guide Oriented Cell Growth and Promote
           Electrophysiological Homogeneity for Synthetic Cardiac Tissues
    • Authors: Jing Ren; Quanfu Xu, Xiaomeng Chen, Wei Li, Kai Guo, Yang Zhao, Qian Wang, Zhitao Zhang, Huisheng Peng, Yi-Gang Li
      Abstract: Cardiac engineering of patches and tissues is a promising option to restore infarcted hearts, by seeding cardiac cells onto scaffolds and nurturing their growth in vitro. However, current patches fail to fully imitate the hierarchically aligned structure in the natural myocardium, the fast electrotonic propagation, and the subsequent synchronized contractions. Here, superaligned carbon-nanotube sheets (SA-CNTs) are explored to culture cardiomyocytes, mimicking the aligned structure and electrical-impulse transmission behavior of the natural myocardium. The SA-CNTs not only induce an elongated and aligned cell morphology of cultured cardiomyocytes, but also provide efficient extracellular signal-transmission pathways required for regular and synchronous cell contractions. Furthermore, the SA-CNTs can reduce the beat-to-beat and cell-to-cell dispersion in repolarization of cultured cells, which is essential for a normal beating rhythm, and potentially reduce the occurrence of arrhythmias. Finally, SA-CNT-based flexible one-piece electrodes demonstrate a multipoint pacing function. These combined high properties make SA-CNTs promising in applications in cardiac resynchronization therapy in patients with heart failure and following myocardial infarctions.A cardiac-tissue-engineering approach to treat myocardial infarction is developed by seeding myocardiocytes on superaligned carbon-nanotube sheets (SA-CNTs). The SA-CNTs can induce an elongated and aligned cell morphology, provide efficient extracellular signal-transmission pathways, and potentially reduce abnormal beating rhythms, which are promising in applications in cardiac resynchronization therapy in patients with heart failure following myocardial infarcts.
      PubDate: 2017-10-11T00:01:47.542113-05:
      DOI: 10.1002/adma.201702713
       
  • Multifunctional Nanohybrid Based on Porous Silicon Nanoparticles, Gold
           Nanoparticles, and Acetalated Dextran for Liver Regeneration and Acute
           Liver Failure Theranostics
    • Authors: Zehua Liu; Yunzhan Li, Wei Li, Chen Xiao, Dongfei Liu, Chao Dong, Ming Zhang, Ermei Mäkilä, Marianna Kemell, Jarno Salonen, Jouni T. Hirvonen, Hongbo Zhang, Dawang Zhou, Xianming Deng, Hélder A. Santos
      Abstract: Herein, a novel nanohybrid based on porous silicon, gold nanoparticles (Au NPs), and acetalated dextran (DPSi/DAu@AcDEX) is reported to encapsulate and deliver one drug and increase the computer tomography (CT) signal for acute-liver-failure (ALF) theranostics. A microfluidic-assisted method is used to co-encapsulate different NPs in a single step. By alternating the surface properties of different NPs and by modulating the composition of the organic phase, both PSi and Au NPs are effectively encapsulated into the polymer matrix simultaneously, thus further achieving a multifunctional application. This system can be used to identify pathologically changes in the tissues and selectively deliver drugs to these sites. The loading of a therapeutic compound (XMU-MP-1) improves the drug solubility, precise, in situ drug delivery, and the drug-functioning time. In vivo results confirm a superior treatment effect and better compliance of this newly developed nanoformulation than free compound. This nanosystem plays a crucial role in targeting the lesion area, thus increasing the local drug concentration important for ALF reverse-effect. Moreover, the residence of Au NPs within the matrix further endows our system for CT-imaging. Altogether, these results support that this nanohybrid is a potential theranostic platform for ALF.A porous silicon-nanoparticle, gold- nanoparticle, and acetalated-dextran-based nanohybrid is designed for acute liver failure (ALF)-reverse- and computer tomography (CT)-imaging-facilitated ALF indication. Lesion-site-specific particle accumulation can increase the local drug concentration, and the resident gold can further function as a CT contrasting agent.
      PubDate: 2017-10-11T00:01:15.632078-05:
      DOI: 10.1002/adma.201703393
       
  • Highly Crystalline C8-BTBT Thin-Film Transistors by Lateral Homo-Epitaxial
           Growth on Printed Templates
    • Authors: Robby Janneck; Nicolas Pilet, Satya Prakash Bommanaboyena, Benjamin Watts, Paul Heremans, Jan Genoe, Cedric Rolin
      Abstract: Highly crystalline thin films of organic semiconductors offer great potential for fundamental material studies as well as for realizing high-performance, low-cost flexible electronics. The fabrication of these films directly on inert substrates is typically done by meniscus-guided coating techniques. The resulting layers show morphological defects that hinder charge transport and induce large device-to-device variability. Here, a double-step method for organic semiconductor layers combining a solution-processed templating layer and a lateral homo-epitaxial growth by a thermal evaporation step is reported. The epitaxial regrowth repairs most of the morphological defects inherent to meniscus-guided coatings. The resulting film is highly crystalline and features a mobility increased by a factor of three and a relative spread in device characteristics improved by almost half an order of magnitude. This method is easily adaptable to other coating techniques and offers a route toward the fabrication of high-performance, large-area electronics based on highly crystalline thin films of organic semiconductors.Highly crystalline organic thin films with average carrier mobilities above 10 cm2 V−1 s−1 and parameter spread below 10% are achieved by a double-step method, combining a solution-processed templating layer and a lateral homo-epitaxial growth by a thermal-evaporation step. The epitaxial regrowth repairs most of the morphological defects inherent to meniscus-guided coating techniques. This improves mobility and spread between devices.
      PubDate: 2017-10-10T07:32:38.178814-05:
      DOI: 10.1002/adma.201703864
       
  • Imbedded Nanocrystals of CsPbBr3 in Cs4PbBr6: Kinetics, Enhanced
           Oscillator Strength, and Application in Light-Emitting Diodes
    • Authors: Junwei Xu; Wenxiao Huang, Peiyun Li, Drew R. Onken, Chaochao Dun, Yang Guo, Kamil B. Ucer, Chang Lu, Hongzhi Wang, Scott M. Geyer, Richard T. Williams, David L. Carroll
      Abstract: Solution-grown films of CsPbBr3 nanocrystals imbedded in Cs4PbBr6 are incorporated as the recombination layer in light-emitting diode (LED) structures. The kinetics at high carrier density of pure (extended) CsPbBr3 and the nanoinclusion composite are measured and analyzed, indicating second-order kinetics in extended and mainly first-order kinetics in the confined CsPbBr3, respectively. Analysis of absorption strength of this all-perovskite, all-inorganic imbedded nanocrystal composite relative to pure CsPbBr3 indicates enhanced oscillator strength consistent with earlier published attribution of the sub-nanosecond exciton radiative lifetime in nanoprecipitates of CsPbBr3 in melt-grown CsBr host crystals and CsPbBr3 evaporated films.Photoluminescence and electroluminescence in solution-grown films of CsPbBr3 nanocrystals imbedded in Cs4PbBr6 are studied. Radiative recombination kinetics are second order in bulk CsPbBr3 and first order in CsPbBr3 nanoinclusions. Exciton absorption strength and sub-nanosecond lifetime imply enhanced oscillator strength in the confined form. A semiconductor that is dark in bulk lights up as a highly efficient and fast nanocomposite light emitter.
      PubDate: 2017-10-10T07:32:20.186123-05:
      DOI: 10.1002/adma.201703703
       
  • Stimulated Transitions of Directed Nonequilibrium Self-Assemblies
    • Authors: Alexander A. Steinschulte; Andrea Scotti, Khosrow Rahimi, Oleksii Nevskyi, Alex Oppermann, Sabine Schneider, Steffen Bochenek, Marie F. Schulte, Karen Geisel, Felicitas Jansen, Andre Jung, Sabrina Mallmann, Roland Winter, Walter Richtering, Dominik Wöll, Ralf Schweins, Nicholas J. Warren, Felix A. Plamper
      Abstract: Near-equilibrium stimulus-responsive polymers have been used extensively to introduce morphological variations in dependence of adaptable conditions. Far-less-well studied are triggered transformations at constant conditions. These require the involvement of metastable states, which are either able to approach the equilibrium state after deviation from metastability or can be frozen on returning from nonequilibrium to equilibrium. Such functional nonequilibrium macromolecular systems hold great promise for on-demand transformations, which result in substantial changes in their material properties, as seen for triggered gelations. Herein, a diblock copolymer system consisting of a hydrophilic block and a block that is responsive to both pressure and temperature, is introduced. This species demonstrates various micellar transformations upon leaving equilibrium/nonequilibrium states, which are triggered by a temperature deflection or a temporary application of hydrostatic pressure.Temporary pressure or temperature deflections induce property and morphology changes of easily prepared and kinetically stable nonequilibrium micelles. These systems allow a stimulated physical gelation at constant conditions before and after trigger application. As an extraordinary example, a specific polymer, which can show all principle micellar morphologies at the same concentration c, pressure p, and temperature T, is highlighted.
      PubDate: 2017-10-10T07:31:50.194171-05:
      DOI: 10.1002/adma.201703495
       
  • Chemical Intercalation of Topological Insulator Grid Nanostructures for
           High-Performance Transparent Electrodes
    • Authors: Yunfan Guo; Jinyuan Zhou, Yujing Liu, Xu Zhou, Fengrui Yao, Congwei Tan, Jinxiong Wu, Li Lin, Kaihui Liu, Zhongfan Liu, Hailin Peng
      Abstract: 2D layered nanomaterials with strong covalent bonding within layers and weak van der Waals' interactions between layers have attracted tremendous interest in recent years. Layered Bi2Se3 is a representative topological insulator material in this family, which holds promise for exploration of the fundamental physics and practical applications such as transparent electrode. Here, a simultaneous enhancement of optical transmittancy and electrical conductivity in Bi2Se3 grid electrodes by copper-atom intercalation is presented. These Cu-intercalated 2D Bi2Se3 electrodes exhibit high uniformity over large area and excellent stabilities to environmental perturbations, such as UV light, thermal fluctuation, and mechanical distortion. Remarkably, by intercalating a high density of copper atoms, the electrical and optical performance of Bi2Se3 grid electrodes is greatly improved from 900 Ω sq−1, 68% to 300 Ω sq−1, 82% in the visible range; with better performance of 300 Ω sq−1, 91% achieved in the near-infrared region. These unique properties of Cu-intercalated topological insulator grid nanostructures may boost their potential applications in high-performance optoelectronics, especially for infrared optoelectronic devices.Both the optical performance and the electrical performance of transparent electrodes based on 2D Bi2Se3 grid nanostructures are simultaneously improved by chemical intercalation in a broadband wavelength. The high density of copper atoms accommodated between the van der Waals' gaps of Bi2Se3 introduces large amounts of free electrons into the host structure, which allows higher transparency, better conductivity, outstanding chemical dura­bility, and mechanical stabilities for Bi2Se3 grid electrodes.
      PubDate: 2017-10-10T07:31:09.092838-05:
      DOI: 10.1002/adma.201703424
       
  • A Fluid Liquid-Crystal Material with Highly Polar Order
    • Authors: Hiroya Nishikawa; Kazuya Shiroshita, Hiroki Higuchi, Yasushi Okumura, Yasuhiro Haseba, Shin-ichi Yamamoto, Koki Sago, Hirotsugu Kikuchi
      Abstract: An anomalously large dielectric permittivity of ≈104 is found in the mesophase temperature range (MP phase) wherein high fluidity is observed for a liquid-crystal compound having a 1,3-dioxane unit in the mesogenic core (DIO). In this temperature range, no sharp X-ray diffraction peak is observed at both small and wide Bragg angles, similar to that for a nematic phase; however, an inhomogeneous sandy texture or broken Schlieren one is observed via polarizing optical microscopy, unlike that for a conventional nematic phase. DIO exhibits polarization switching with a large polarization value, i.e., P = 4.4 µC cm−2, and a parallelogram-shaped polarization–electric field hysteresis loop in the MP phase. The inhomogeneously aligned DIO in the absence of an electric field adopts a uniform orientation along an applied electric field when field-induced polarization switching occurs. Furthermore, sufficiently larger second-harmonic generation is observed for DIO in the MP phase. Second-harmonic-generation interferometry clearly shows that the sense of polarization is inverted when the +/− sign of the applied electric field in MP is reversed. These results suggest that a unidirectional, ferroelectric-like parallel polar arrangement of the molecules is generated along the director in the MP phase.An anomalously large dielectric permittivity of ≈104 is found for a liquid-crystal compound having a 1,3-dioxane unit (DIO) in the high-fluid mesophase temperature range. In addition, DIO shows ferroelectric-like polarization of 4.4 µC cm−2, which is several hundred times larger than those of conventional ferroelectric chiral smectic C materials, and second-harmonic-generation activity.
      PubDate: 2017-10-10T07:30:44.098684-05:
      DOI: 10.1002/adma.201702354
       
  • Tree-Inspired Design for High-Efficiency Water Extraction
    • Authors: Mingwei Zhu; Yiju Li, Guang Chen, Feng Jiang, Zhi Yang, Xiaoguang Luo, Yanbin Wang, Steven D. Lacey, Jiaqi Dai, Chengwei Wang, Chao Jia, Jiayu Wan, Yonggang Yao, Amy Gong, Bao Yang, Zongfu Yu, Siddhartha Das, Liangbing Hu
      Abstract: The solar steam process, akin to the natural water cycle, is considered to be an attractive approach to address water scarcity issues globally. However, water extraction from groundwater, for example, has not been demonstrated using these existing technologies. Additionally, there are major unaddressed challenges in extracting potable water from seawater including salt accumulation and long-term evaporation stability, which warrant further investigation. Herein, a high-performance solar steam device composed entirely of natural wood is reported. The pristine, natural wood is cut along the transverse direction and the top surface is carbonized to create a unique bilayer structure. This tree-inspired design offers distinct advantages for water extraction, including rapid water transport and evaporation in the mesoporous wood, high light absorption (≈99%) within the surface carbonized open wood channels, a low thermal conductivity to avoid thermal loss, and cost effectiveness. The device also exhibits long-term stability in seawater without salt accumulation as well as high performance for underground water extraction. The tree-inspired design offers an inexpensive and scalable solar energy harvesting and steam generation technology that can provide clean water globally, especially for rural or remote areas where water is not only scarce but also limited by water extraction materials and methods.A bilayer tree-inspired design is fabricated for application as high-performance solar steam generation device. The all-wood device demonstrates high efficiency in water extraction from both seawater and groundwater, long-term stability in seawater without salt accumulation, and maintains production cost as low as ≈$1 m−2.
      PubDate: 2017-10-10T06:06:30.100288-05:
      DOI: 10.1002/adma.201704107
       
  • Slow-Photon-Effect-Induced Photoelectrical-Conversion Efficiency
           Enhancement for Carbon-Quantum-Dot-Sensitized Inorganic CsPbBr3 Inverse
           Opal Perovskite Solar Cells
    • Authors: Shujie Zhou; Rui Tang, Longwei Yin
      Abstract: All-inorganic cesium lead halide perovskite is suggested as a promising candidate for perovskite solar cells due to its prominent thermal stability and comparable light absorption ability. Designing textured perovskite films rather than using planar-architectural perovskites can indeed optimize the optical and photoelectrical conversion performance of perovskite photovoltaics. Herein, for the first time, this study demonstrates a rational strategy for fabricating carbon quantum dot (CQD-) sensitized all-inorganic CsPbBr3 perovskite inverse opal (IO) films via a template-assisted, spin-coating method. CsPbBr3 IO introduces slow-photon effect from tunable photonic band gaps, displaying novel optical response property visible to naked eyes, while CQD inlaid among the IO frameworks not only broadens the light absorption range but also improves the charge transfer process. Applied in the perovskite solar cells, compared with planar CsPbBr3, slow-photon effect of CsPbBr3 IO greatly enhances the light utilization, while CQD effectively facilitates the electron–hole extraction and injection process, prolongs the carrier lifetime, jointly contributing to a double-boosted power conversion efficiency (PCE) of 8.29% and an increased incident photon-to-electron conversion efficiency of up to 76.9%. The present strategy on CsPbBr3 IO to enhance perovskite PCE can be extended to rationally design other novel optoelectronic devices.Novel carbon quantum dot (CQD) sensitized inorganic CsPbBr3 inverse opal perovskite solar cells are for the first time fabricated. CsPbBr3 inverse opal induces improved light utilization originating from the slow-photon effect with tunable photonic band gaps, while CQD helps to facilitate the charge transfer process, which jointly contributes to a greatly improved photoelectrical conversion efficiency with outstanding stability.
      PubDate: 2017-10-10T04:46:37.962822-05:
      DOI: 10.1002/adma.201703682
       
  • Unraveling the Mystery of the Blue Fog: Structure, Properties, and
           Applications of Amorphous Blue Phase III
    • Authors: Sahil Sandesh Gandhi; Liang-Chy Chien
      Abstract: The amorphous blue phase III of cholesteric liquid crystals, also known as the “blue fog,” are among the rising stars in materials science that can potentially be used to develop next-generation displays with the ability to compete toe-to-toe with disruptive technologies like organic light-emitting diodes. The structure and properties of the practically unobservable blue phase III have eluded scientists for more than a century since it was discovered. This progress report reviews the developments in this field from both fundamental and applied research perspectives. The first part of this progress report gives an overview of the 130-years-long scientific tour-de-force that very recently resulted in the revelation of the mysterious structure of blue phase III. The second part reviews progress made in the past decade in developing electrooptical, optical, and photonic devices based on blue phase III. The strong and weak aspects of the development of these devices are underlined and criticized, respectively. The third- and-final part proposes ideas for further improvement in blue phase III technology to make it feasible for commercialization and widespread use.The structure and properties of the amorphous blue phase III of cholesteric liquid crystals have been a topic of intense debate among scientists in the soft matter community for more than a century. This progress report provides an update on the current status of materials and electrooptical, optical, and photonic devices based on this hitherto mysterious phase of matter.
      PubDate: 2017-10-10T00:23:37.036717-05:
      DOI: 10.1002/adma.201704296
       
  • Realization of Large Electric Polarization and Strong Magnetoelectric
           Coupling in BiMn3Cr4O12
    • Authors: Long Zhou; Jianhong Dai, Yisheng Chai, Huimin Zhang, Shuai Dong, Huibo Cao, Stuart Calder, Yunyu Yin, Xiao Wang, Xudong Shen, Zhehong Liu, Takashi Saito, Yuichi Shimakawa, Hajime Hojo, Yuichi Ikuhara, Masaki Azuma, Zhiwei Hu, Young Sun, Changqing Jin, Youwen Long
      Abstract: Magnetoelectric multiferroics have received much attention in the past decade due to their interesting physics and promising multifunctional performance. For practical applications, simultaneous large ferroelectric polarization and strong magnetoelectric coupling are preferred. However, these two properties have not been found to be compatible in the single-phase multiferroic materials discovered as yet. Here, it is shown that superior multiferroic properties exist in the A-site ordered perovskite BiMn3Cr4O12 synthesized under high-pressure and high-temperature conditions. The compound experiences a ferroelectric phase transition ascribed to the 6s2 lone-pair effects of Bi3+ at around 135 K, and a long-range antiferromagnetic order related to the Cr3+ spins around 125 K, leading to the presence of a type-I multiferroic phase with huge electric polarization. On further cooling to 48 K, a type-II multiferroic phase induced by the special spin structure composed of both Mn- and Cr-sublattices emerges, accompanied by considerable magnetoelectric coupling. BiMn3Cr4O12 thus provides a rare example of joint multiferroicity, where two different types of multiferroic phases develop subsequently so that both large polarization and significant magnetoelectric effect are achieved in a single-phase multiferroic material.The A-sited ordered perovskite BiMn3Cr4O12 presents a rare example of single-phase multiferroic systems where both type-I and type-II multiferroic phases coexist. In sharp contrast to previous findings, large electric polarization and strong magnetoelectric effect are compatible in the current BiMn3Cr4O12, providing a new pathway for generating advanced multiferroic materials and devices.
      PubDate: 2017-10-09T07:36:33.898682-05:
      DOI: 10.1002/adma.201703435
       
  • An Ultrastable and High-Performance Flexible Fiber-Shaped Ni–Zn Battery
           based on a Ni–NiO Heterostructured Nanosheet Cathode
    • Authors: Yinxiang Zeng; Yue Meng, Zhengzhe Lai, Xiyue Zhang, Minghao Yu, Pingping Fang, Mingmei Wu, Yexiang Tong, Xihong Lu
      Abstract: Currently, the main bottleneck for the widespread application of Ni–Zn batteries is their poor cycling stability as a result of the irreversibility of the Ni-based cathode and dendrite formation of the Zn anode during the charging–discharging processes. Herein, a highly rechargeable, flexible, fiber-shaped Ni–Zn battery with impressive electrochemical performance is rationally demonstrated by employing Ni–NiO heterostructured nanosheets as the cathode. Benefiting from the improved conductivity and enhanced electroactivity of the Ni–NiO heterojunction nanosheet cathode, the as-fabricated fiber-shaped Ni–NiO//Zn battery displays high capacity and admirable rate capability. More importantly, this Ni–NiO//Zn battery shows unprecedented cyclic durability both in aqueous (96.6% capacity retention after 10 000 cycles) and polymer (almost no capacity attenuation after 10 000 cycles at 22.2 A g−1) electrolytes. Moreover, a peak energy density of 6.6 µWh cm−2, together with a remarkable power density of 20.2 mW cm−2, is achieved by the flexible quasi-solid-state fiber-shaped Ni–NiO//Zn battery, outperforming most reported fiber-shaped energy-storage devices. Such a novel concept of a fiber-shaped Ni–Zn battery with impressive stability will greatly enrich the flexible energy-storage technologies for future portable/wearable electronic applications.An ultrastable, flexible fiber-shaped Ni–Zn battery with impressive electrochemical performance is rationally demonstrated by employing Ni–NiO heterostructured nanosheets as the cathode. This Ni–NiO//Zn battery exhibits unprecedented cyclic durability both in aqueous (96.6% capacity retention after 10 000 cycles) and polymer (almost no capacity attenuation after 10 000 cycles at 22.2 A g−1) electrolytes.
      PubDate: 2017-10-09T07:35:50.726689-05:
      DOI: 10.1002/adma.201702698
       
  • Magnetically Controlled Growth-Factor-Immobilized Multilayer Cell Sheets
           for Complex Tissue Regeneration
    • Authors: Wenjie Zhang; Guangzheng Yang, Xiansong Wang, Liting Jiang, Fei Jiang, Guanglong Li, Zhiyuan Zhang, Xinquan Jiang
      Abstract: The scaffold-free cell-sheet technique plays a significant role in stem-cell-based regeneration. Furthermore, growth factors are known to direct stem cell differentiation and enhance tissue regeneration. However, the absence of an effective means to incorporate growth factors into the cell sheets hinders further optimization of the regeneration efficiency. Here, a novel design of magnetically controlled “growth-factor-immobilized cell sheets” is reported. A new Fe3O4 magnetic nanoparticle (MNP) coated with nanoscale graphene oxide (nGO@Fe3O4) is developed to label stem cells and deliver growth factors. First, the nGO@Fe3O4 MNPs can be easily swallowed by dental-pulp stem cells (DPSCs) and have no influence on cell viability. Thus, the MNP-labeled cells can be organized via magnetic force to form multilayered cell sheets in different patterns. Second, compared to traditional Fe3O4 nanoparticles, the graphene oxide coating provides plenty of carboxyl groups to bind and deliver growth factors. Therefore, with these nGO@Fe3O4 MNPs, bone-morphogenetic-protein-2 (BMP2) is successfully incorporated into the DPSCs sheets to induce more bone formation. Furthermore, an integrated osteochondral complex is also constructed using a combination of DPSCs/TGFβ3 and DPSCs/BMP2. All these results demonstrate that the new cell-sheet tissue-engineering approach exhibits promising potential for future use in regenerative medicine.A novel design for “growth-factor-immobilized cell sheets” formed under the control of magnetic force is introduced to optimize regeneration efficiency, based on a new nanoscale graphene-oxide-coated Fe3O4 magnetic nanoparticle. The nanocomposites provide a novel magnetically controlled vehicle for delivery of both stem cells and growth factors, and they exhibit promising potential for future use in regenerative medicine.
      PubDate: 2017-10-09T07:34:02.830994-05:
      DOI: 10.1002/adma.201703795
       
  • High-Performance Flexible Photodetectors based on High-Quality Perovskite
           Thin Films by a Vapor–Solution Method
    • Authors: Wei Hu; Wei Huang, Shuzhen Yang, Xiao Wang, Zhenyu Jiang, Xiaoli Zhu, Hong Zhou, Hongjun Liu, Qinglin Zhang, Xiujuan Zhuang, Junliang Yang, Dong Ha Kim, Anlian Pan
      Abstract: Organometal halide perovskites are new light-harvesting materials for lightweight and flexible optoelectronic devices due to their excellent optoelectronic properties and low-temperature process capability. However, the preparation of high-quality perovskite films on flexible substrates has still been a great challenge to date. Here, a novel vapor–solution method is developed to achieve uniform and pinhole-free organometal halide perovskite films on flexible indium tin oxide/poly(ethylene terephthalate) substrates. Based on the as-prepared high-quality perovskite thin films, high-performance flexible photodetectors (PDs) are constructed, which display a nR value of 81 A W−1 at a low working voltage of 1 V, three orders higher than that of previously reported flexible perovskite thin-film PDs. In addition, these flexible PDs exhibit excellent flexural stability and durability under various bending situations with their optoelectronic performance well retained. This breakthrough on the growth of high-quality perovskite thin films opens up a new avenue to develop high-performance flexible optoelectronic devices.A novel vapor–solution method is developed to achieve uniform and pinhole-free organometal halide perovskite films on flexible indium tin oxide/poly(ethylene terephthalate) substrates. Based on the as-prepared high-quality perovskite thin films, high-performance flexible photodetectors are constructed with a very high R value, excellent flexural stability, and durability under various bending situations.
      PubDate: 2017-10-09T07:31:58.666229-05:
      DOI: 10.1002/adma.201703256
       
  • Rational In Silico Design of an Organic Semiconductor with Improved
           Electron Mobility
    • Authors: Pascal Friederich; Verónica Gómez, Christian Sprau, Velimir Meded, Timo Strunk, Michael Jenne, Andrea Magri, Franz Symalla, Alexander Colsmann, Mario Ruben, Wolfgang Wenzel
      Abstract: Organic semiconductors find a wide range of applications, such as in organic light emitting diodes, organic solar cells, and organic field effect transistors. One of their most striking disadvantages in comparison to crystalline inorganic semiconductors is their low charge-carrier mobility, which manifests itself in major device constraints such as limited photoactive layer thicknesses. Trial-and-error attempts to increase charge-carrier mobility are impeded by the complex interplay of the molecular and electronic structure of the material with its morphology. Here, the viability of a multiscale simulation approach to rationally design materials with improved electron mobility is demonstrated. Starting from one of the most widely used electron conducting materials (Alq3), novel organic semiconductors with tailored electronic properties are designed for which an improvement of the electron mobility by three orders of magnitude is predicted and experimentally confirmed.The viability of a multiscale simulation approach to rationally design organic semiconductors with improved electron mobility is demonstrated. Novel materials with tailored electronic properties are designed for which an improvement of the electron mobility by three orders of magnitude is predicted and experimentally confirmed.
      PubDate: 2017-10-09T07:31:14.229362-05:
      DOI: 10.1002/adma.201703505
       
  • Wrinkled 2D Materials: A Versatile Platform for Low-Threshold Stretchable
           Random Lasers
    • Authors: Han-Wen Hu; Golam Haider, Yu-Ming Liao, Pradip Kumar Roy, Rini Ravindranath, Huan-Tsung Chang, Cheng-Hsin Lu, Chang-Yang Tseng, Tai-Yung Lin, Wei-Heng Shih, Yang-Fang Chen
      Abstract: A stretchable, flexible, and bendable random laser system capable of lasing in a wide range of spectrum will have many potential applications in next- generation technologies, such as visible-spectrum communication, superbright solid-state lighting, biomedical studies, fluorescence, etc. However, producing an appropriate cavity for such a wide spectral range remains a challenge owing to the rigidity of the resonator for the generation of coherent loops. 2D materials with wrinkled structures exhibit superior advantages of high stretchability and a suitable matrix for photon trapping in between the hill and valley geometries compared to their flat counterparts. Here, the intriguing functionalities of wrinkled reduced graphene oxide, single-layer graphene, and few-layer hexagonal boron nitride, respectively, are utilized to design highly stretchable and wearable random laser devices with ultralow threshold. Using methyl-ammonium lead bromide perovskite nanocrystals (PNC) to illustrate the working principle, the lasing threshold is found to be ≈10 µJ cm−2, about two times less than the lowest value ever reported. In addition to PNC, it is demonstrated that the output lasing wavelength can be tuned using different active materials such as semiconductor quantum dots. Thus, this study is very useful for the future development of high-performance wearable optoelectronic devices.2D materials with wrinkled structures exhibit superior advantages of high stretchability, along with a suitable matrix for photon trapping in between the hill and valley geometries compared to their flat counterparts. This is the first attempt to integrate wrinkled 2D materials with a random laser system, which enables highly stretchable and wearable random laser devices with ultralow threshold to be designed.
      PubDate: 2017-10-09T07:30:53.606543-05:
      DOI: 10.1002/adma.201703549
       
  • Enhanced Open-Circuit Voltage in Colloidal Quantum Dot Photovoltaics via
           Reactivity-Controlled Solution-Phase Ligand Exchange
    • Authors: Jea Woong Jo; Younghoon Kim, Jongmin Choi, F. Pelayo García Arquer, Grant Walters, Bin Sun, Olivier Ouellette, Junghwan Kim, Andrew H. Proppe, Rafael Quintero-Bermudez, James Fan, Jixian Xu, Chih Shan Tan, Oleksandr Voznyy, Edward H. Sargent
      Abstract: The energy disorder that arises from colloidal quantum dot (CQD) polydispersity limits the open-circuit voltage (VOC) and efficiency of CQD photovoltaics. This energy broadening is significantly deteriorated today during CQD ligand exchange and film assembly. Here, a new solution-phase ligand exchange that, via judicious incorporation of reactivity-engineered additives, provides improved monodispersity in final CQD films is reported. It has been found that increasing the concentration of the less reactive species prevents CQD fusion and etching. As a result, CQD solar cells with a VOC of 0.7 V (vs 0.61 V for the control) for CQD films with exciton peak at 1.28 eV and a power conversion efficiency of 10.9% (vs 10.1% for the control) is achieved.A new solution-phase ligand exchange method for preventing colloidal quantum dots fusion and etching is developed via judicious incorporation of reactivity-engineered additives. This method provides improved monodispersity in final colloidal quantum dot films and thus leads to the significant enhancement of open-circuit voltages in colloidal quantum dot solar cells.
      PubDate: 2017-10-09T07:30:28.78476-05:0
      DOI: 10.1002/adma.201703627
       
  • In Situ GIWAXS Analysis of Solvent and Additive Effects on PTB7 Thin Film
           Microstructure Evolution during Spin Coating
    • Authors: Eric F. Manley; Joseph Strzalka, Thomas J. Fauvell, Nicholas E. Jackson, Matthew J. Leonardi, Nicholas D. Eastham, Tobin J. Marks, Lin X. Chen
      Abstract: The influence of solvent and processing additives on the pathways and rates of crystalline morphology formation for spin-coated semiconducting PTB7 (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]]) thin films is investigated by in situ grazing incidence wide-angle X-ray scattering (GIWAXS) and optical reflectance, to better understand polymer solar cell (PSC) optimization approaches. In situ characterization of PTB7 film formation from chloroform (CF), chlorobenzene (CB), and 1,2-dichlorobenzene (DCB) solutions, as well as CB solutions with 1% and 3% v/v of the processing additives 1-chloronapthalene (CN), diphenylether (DPE), and 1,8-diiodooctane (DIO), reveals multiple crystallization pathways with: (i) single-solvent systems exhibiting rapid (
      PubDate: 2017-10-09T00:33:34.317614-05:
      DOI: 10.1002/adma.201703933
       
  • Re Doping in 2D Transition Metal Dichalcogenides as a New Route to Tailor
           Structural Phases and Induced Magnetism
    • Authors: Vidya Kochat; Amey Apte, Jordan A. Hachtel, Hiroyuki Kumazoe, Aravind Krishnamoorthy, Sandhya Susarla, Juan Carlos Idrobo, Fuyuki Shimojo, Priya Vashishta, Rajiv Kalia, Aiichiro Nakano, Chandra Sekhar Tiwary, Pulickel M. Ajayan
      Abstract: Alloying in 2D results in the development of new, diverse, and versatile systems with prospects in bandgap engineering, catalysis, and energy storage. Tailoring structural phase transitions using alloying is a novel idea with implications in designing all 2D device architecture as the structural phases in 2D materials such as transition metal dichalcogenides are correlated with electronic phases. Here, this study develops a new growth strategy employing chemical vapor deposition to grow monolayer 2D alloys of Re-doped MoSe2 with show composition tunable structural phase variations. The compositions where the phase transition is observed agree well with the theoretical predictions for these 2D systems. It is also shown that in addition to the predicted new electronic phases, these systems also provide opportunities to study novel phenomena such as magnetism which broadens the range of their applications.Re doping is demonstrated to be a controllable way to tailor crystal structure and magnetic properties in chemical vapor deposition (CVD)-synthesized 2D transition metal dichalcogenides. Extra electrons from Re atoms induce a 2H–1T′ phase transformation in monolayer Mo1–xRexSe2 alloys. These results show that chemical doping is a promising pathway to tune structural and magnetic properties of other CVD-grown MX2 (M = Mo, W; X = S, Se).
      PubDate: 2017-10-09T00:30:21.873026-05:
      DOI: 10.1002/adma.201703754
       
  • Autonomous Ex Novo Chemical Assembly with Blebbing and Division of
           Functional Polymer Vesicles from a “Homogeneous Mixture”
    • Authors: Bishnu Prasad Bastakoti; Juan Perez-Mercader
      Abstract: The chemical energy and radicals from an oscillating chemical reaction are used to synthesize a polymer vesicle from a homogeneous solution of monomeric units. Periodically formed radicals from the Belousov–Zhabotinsky (B–Z) reaction initiate radical polymerization between a polyethylene glycol based chain transfer agent (PEG-CTA) and hydrophilic acrylonitrile monomers in water. The growth of a hydrophobic chain on the hydrophilic PEG chain induces self-assembly of polymeric amphiphiles to form micrometer-sized vesicles entrapping an active oscillating B–Z reaction. In our experimental conditions, the different chemical environments inside and outside the vesicles contribute to enlarge the area and diameter of the resulting self-assembled vesicles and, in some cases, promote blebbing and division.This study discusses the synthesis of amphiphilic block copolymers that self-assemble into micrometer-sized vesicles, while simultaneously entrapping the reaction that provides the radicals needed for the polymerization and shows their blebbing, a first step to system division, due to an internal reaction. The system does not use any biochemistry.
      PubDate: 2017-10-06T09:05:09.864522-05:
      DOI: 10.1002/adma.201704368
       
  • A Twisted Thieno[3,4-b]thiophene-Based Electron Acceptor Featuring a
           14-π-Electron Indenoindene Core for High-Performance Organic
           Photovoltaics
    • Authors: Sheng jie Xu; Zichun Zhou, Wuyue Liu, Zhongbo Zhang, Feng Liu, Hongping Yan, Xiaozhang Zhu
      Abstract: With an indenoindene core, a new thieno[3,4-b]thiophene-based small-molecule electron acceptor, 2,2′-((2Z,2′Z)-((6,6′-(5,5,10,10-tetrakis(2-ethylhexyl)-5,10-dihydroindeno[2,1-a]indene-2,7-diyl)bis(2-octylthieno[3,4-b]thiophene-6,4-diyl))bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (NITI), is successfully designed and synthesized. Compared with 12-π-electron fluorene, a carbon-bridged biphenylene with an axial symmetry, indenoindene, a carbon-bridged E-stilbene with a centrosymmetry, shows elongated π-conjugation with 14 π-electrons and one more sp3 carbon bridge, which may increase the tunability of electronic structure and film morphology. Despite its twisted molecular framework, NITI shows a low optical bandgap of 1.49 eV in thin film and a high molar extinction coefficient of 1.90 × 105m−1 cm−1 in solution. By matching NITI with a large-bandgap polymer donor, an extraordinary power conversion efficiency of 12.74% is achieved, which is among the best performance so far reported for fullerene-free organic photovoltaics and is inspiring for the design of new electron acceptors.A thieno[3,4-b]thiophene-based electron acceptor, NITI, featuring a 14-π-electron indenoindene core is designed and synthesized. Despite its twisted molecular geometry, NITI shows a low optical bandgap and a high molar extinction coefficient. By matching NITI with a large-bandgap polymer donor, an extraordinary power conversion efficiency of 12.74% is achieved, which represents an exciting progress in the design of new electron acceptors.
      PubDate: 2017-10-06T09:04:45.64291-05:0
      DOI: 10.1002/adma.201704510
       
  • Shorter Exciton Lifetimes via an External Heavy-Atom Effect: Alleviating
           the Effects of Bimolecular Processes in Organic Light-Emitting Diodes
    • Authors: Markus Einzinger; Tianyu Zhu, Piotr de Silva, Christian Belger, Timothy M. Swager, Troy Van Voorhis, Marc A. Baldo
      Abstract: Multiexcited-state phenomena are believed to be the root cause of two exigent challenges in organic light-emitting diodes; namely, efficiency roll-off and degradation. The development of novel strategies to reduce exciton densities under heavy load is therefore highly desirable. Here, it is shown that triplet exciton lifetimes of thermally activated delayed-fluorescence-emitter molecules can be manipulated in the solid state by exploiting intermolecular interactions. The external heavy-atom effect of brominated host molecules leads to increased spin–orbit coupling, which in turn enhances intersystem crossing rates in the guest molecule. Wave function overlap between the host and the guest is confirmed by combined molecular dynamics and density functional theory calculations. Shorter triplet exciton lifetimes are observed, while high photoluminescence quantum yields and essentially unaltered emission spectra are maintained. A change in the intersystem crossing rate ratio due to increased dielectric constants leads to almost 50% lower triplet exciton densities in the emissive layer in the steady state and results in an improved onset of the photoluminescence quantum yield roll-off at high excitation densities. Efficient organic light-emitting diodes with better roll-off behavior based on these novel hosts are fabricated, demonstrating the suitability of this concept for real-world applications.Brominated hosts with an external heavy-atom effect lead to shorter triplet exciton lifetimes in thermally activated, delayed-fluorescence guest molecules due to increased spin–orbit coupling and intersystem crossing rates. Combined with externally manipulated singlet–triplet splitting of the dopants, this results in enhanced onsets of the photoluminescence quantum yield roll-off and fabrication of organic light-emitting diodes with improved droop behavior.
      PubDate: 2017-09-11T10:35:52.644683-05:
      DOI: 10.1002/adma.201701987
       
  • The Role of Rubidium in Multiple-Cation-Based High-Efficiency Perovskite
           Solar Cells
    • Authors: Pankaj Yadav; M. Ibrahim Dar, Neha Arora, Essa A. Alharbi, Fabrizio Giordano, Shaik Mohammed Zakeeruddin, Michael Grätzel
      Abstract: Perovskite solar cells (PSCs) based on cesium (Cs)- and rubidium (Rb)-containing perovskite films show highly reproducible performance; however, a fundamental understanding of these systems is still emerging. Herein, this study has systematically investigated the role of Cs and Rb cations in complete devices by examining the transport and recombination processes using current–voltage characteristics and impedance spectroscopy in the dark. As the credibility of these measurements depends on the performance of devices, this study has chosen two different PSCs, (MAFACs)Pb(IBr)3 (MA = CH3NH3+, FA = CH(NH2)2+) and (MAFACsRb)Pb(IBr)3, yielding impressive performances of 19.5% and 21.1%, respectively. From detailed studies, this study surmises that the confluence of the low trap-assisted charge-carrier recombination, low resistance offered to holes at the perovskite/2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9-spirobifluorene interface with a low series resistance (Rs), and low capacitance leads to the realization of higher performance when an extra Rb cation is incorporated into the absorber films. This study provides a thorough understanding of the impact of inorganic cations on the properties and performance of highly efficient devices, and also highlights new strategies to fabricate efficient multiple-cation-based PSCs.The confluence of low trap-assisted charge-carrier recombination, low resistance offered to holes at the perovskite/2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9-spirobifluorene interface with a low series resistance (RS) and a lower value of charge storage, leads to the realization of higher photovoltaic performance when an extra cation (Rb) is incorporated into the perovskite films.
      PubDate: 2017-09-11T10:35:34.519121-05:
      DOI: 10.1002/adma.201701077
       
  • Self-Assembly of an Amphiphilic Janus Camptothecin–Floxuridine Conjugate
           into Liposome-Like Nanocapsules for More Efficacious Combination
           Chemotherapy in Cancer
    • Authors: Xiaolong Liang; Chuang Gao, Ligang Cui, Shumin Wang, Jinrui Wang, Zhifei Dai
      Abstract: The combination of camptothecin (CPT) and fluoropyrimidine derivatives acts synergistically at a 1:1 molar ratio. Practically, the greatest challenge is the development of a single liposomal formulation that can both encapsulate and maintain this drug combination at an exact 1:1 ratio to achieve coordinated pharmacokinetics. Consequently, a new type of liposome-like nanocapsule (NC) is developed from a highly symmetric Janus camptothecin–floxuridine conjugate (JCFC) amphiphile, which is synthesized by coupling two hydrophobic CPT molecules and two hydrophilic floxuridine (FUDR) molecules to multivalent pentaerythritol via a hydrolyzable ester linkage. JCFC NCs possess remarkably high drug-loading contents, and no premature release because of the highly stable co-delivery of the drug combination without the need for any carrier. It is shown that JCFC NCs consistently provide synergy and avoid antagonism in a broad panel of tumor cell lines. In vivo delivery of JCFC NCs leads to longer blood retention half-life, higher tumorous accumulation and cellular uptake of drugs, and greatly enhanced efficacy in murine tumor models compared to CPT, FUDR, and CPT + FUDR. This liposomal strategy can be extended to other hydrophilic and hydrophobic anticancer drugs that are coupled to pentaerythritol to self-assemble into nanocapsules for drug self-delivery, pointing to potential clinical translation in near future.Novel liposome-like nanocapsules (NCs) are successfully developed from a highly symmetric Janus camptothecin–floxuridine conjugate (JCFC) amphiphile. JCFC NCs can deliver and preserve a fixed 1:1 molar ratio of the two drugs in a liposomal manner that can suppress premature burst release and coordinate the pharmacokinetics of different drugs after administration, thus resulting in higher apoptotic rate and synergetic anticancer activity.
      PubDate: 2017-09-11T01:37:53.409298-05:
      DOI: 10.1002/adma.201703135
       
  • Stable Li Metal Anodes via Regulating Lithium Plating/Stripping in
           Vertically Aligned Microchannels
    • Authors: Shu-Hua Wang; Ya-Xia Yin, Tong-Tong Zuo, Wei Dong, Jin-Yi Li, Ji-Lei Shi, Chang-Huan Zhang, Nian-Wu Li, Cong-Ju Li, Yu-Guo Guo
      Abstract: Li anodes have been rapidly developed in recent years owing to the rising demand for higher-energy-density batteries. However, the safety issues induced by dendrites hinder the practical applications of Li anodes. Here, Li metal anodes stabilized by regulating lithium plating/stripping in vertically aligned microchannels are reported. The current density distribution and morphology evolution of the Li deposits on porous Cu current collectors are systematically analyzed. Based on simulations in COMSOL Multiphysics, the tip effect leads to preferential deposition on the microchannel walls, thus taking full advantage of the lightening rod theory of classical electromagnetism for restraining growth of Li dendrites. The Li anode with a porous Cu current collector achieves an enhanced cycle stability and a higher average Coulombic efficiency of 98.5% within 200 cycles. In addition, the resultant LiFePO4/Li full battery demonstrates excellent rate capability and stable cycling performance, thus demonstrating promise as a current collector for high-energy-density, safe rechargeable Li batteries.A new strategy to restrain lithium dendrite growth is proposed and demonstrated using vertically aligned microchannel Cu current collectors for Li metal anodes. Most of the lithium is preferentially deposited into the microchannels. The current-density distribution, deposition behavior, and electrochemical performance are simulated and investigated experimentally to understand the effectiveness of the microchannel structure.
      PubDate: 2017-09-11T01:37:07.383618-05:
      DOI: 10.1002/adma.201703729
       
  • Hybrid 3D Printing of Soft Electronics
    • Authors: Alexander D. Valentine; Travis A. Busbee, John William Boley, Jordan R. Raney, Alex Chortos, Arda Kotikian, John Daniel Berrigan, Michael F. Durstock, Jennifer A. Lewis
      Abstract: Hybrid 3D printing is a new method for producing soft electronics that combines direct ink writing of conductive and dielectric elastomeric materials with automated pick-and-place of surface mount electronic components within an integrated additive manufacturing platform. Using this approach, insulating matrix and conductive electrode inks are directly printed in specific layouts. Passive and active electrical components are then integrated to produce the desired electronic circuitry by using an empty nozzle (in vacuum-on mode) to pick up individual components, place them onto the substrate, and then deposit them (in vacuum-off mode) in the desired location. The components are then interconnected via printed conductive traces to yield soft electronic devices that may find potential application in wearable electronics, soft robotics, and biomedical devices.Hybrid 3D printing combines direct writing of stretchable conductive traces (electrodes) and elastomeric matrices with automated pick and place of surface mount electrical components, e.g., light-emitting diodes, to create soft electronic devices, such as wearable sensors.
      PubDate: 2017-09-06T02:00:02.096952-05:
      DOI: 10.1002/adma.201703817
       
  • A Eutectic Mixture of Natural Fatty Acids Can Serve as the Gating Material
           for Near-Infrared-Triggered Drug Release
    • Authors: Chunlei Zhu; Da Huo, Qiaoshan Chen, Jiajia Xue, Song Shen, Younan Xia
      Abstract: A smart release system responsive to near-infrared (NIR) light is developed for intracellular drug delivery. The concept is demonstrated by coencapsulating doxorubicin (DOX) (an anticancer drug) and IR780 iodide (IR780) (an NIR-absorbing dye) into nanoparticles made of a eutectic mixture of naturally occurring fatty acids. The eutectic mixture has a well-defined melting point at 39 °C, and can be used as a biocompatible phase-change material for NIR-triggered drug release. The resultant nanoparticles exhibit prominent photothermal effect and quick drug release in response to NIR irradiation. Fluorescence microscopy analysis indicates that the DOX trapped in the nanoparticles can be efficiently released into the cytosol under NIR irradiation, resulting in enhanced anticancer activity. A new platform is thus offered for designing effective intracellular drug-release systems, holding great promise for future cancer therapy.A smart system responsive to near-infrared (NIR) light is developed by coencapsulating a drug and an NIR-absorbing dye into nanoparticles made of a eutectic mixture of naturally occurring fatty acids. Photothermal heating under NIR irradiation facilitates rapid and efficient intracellular drug release, leading to enhancement in anticancer activity.
      PubDate: 2017-09-05T07:26:45.571094-05:
      DOI: 10.1002/adma.201703702
       
  • Nanolattices: An Emerging Class of Mechanical Metamaterials
    • Authors: Jens Bauer; Lucas R. Meza, Tobias A. Schaedler, Ruth Schwaiger, Xiaoyu Zheng, Lorenzo Valdevit
      Abstract: In 1903, Alexander Graham Bell developed a design principle to generate lightweight, mechanically robust lattice structures based on triangular cells; this has since found broad application in lightweight design. Over one hundred years later, the same principle is being used in the fabrication of nanolattice materials, namely lattice structures composed of nanoscale constituents. Taking advantage of the size-dependent properties typical of nanoparticles, nanowires, and thin films, nanolattices redefine the limits of the accessible material-property space throughout different disciplines. Herein, the exceptional mechanical performance of nanolattices, including their ultrahigh strength, damage tolerance, and stiffness, are reviewed, and their potential for multifunctional applications beyond mechanics is examined. The efficient integration of architecture and size-affected properties is key to further develop nanolattices. The introduction of a hierarchical architecture is an effective tool in enhancing mechanical properties, and the eventual goal of nanolattice design may be to replicate the intricate hierarchies and functionalities observed in biological materials. Additive manufacturing and self-assembly techniques enable lattice design at the nanoscale; the scaling-up of nanolattice fabrication is currently the major challenge to their widespread use in technological applications.Nanolattices are highly ordered three-dimensional architectures composed of nanoscale constituents, and have, in the recent past, redefined the limits of the accessible material-property space throughout different disciplines. The exceptional mechanical properties of nanolattices, including their ultrahigh strength, damage tolerance, and stiffness, are reviewed, and their potential for multifunctional applications beyond mechanics, relevant fabrication methods, and future directions are discussed.
      PubDate: 2017-09-05T07:26:27.14938-05:0
      DOI: 10.1002/adma.201701850
       
  • Hollow-Structured Graphene–Silicone-Composite-Based Piezoresistive
           Sensors: Decoupled Property Tuning and Bending Reliability
    • Authors: Ningqi Luo; Yan Huang, Jing Liu, Shih-Chi Chen, Ching Ping Wong, Ni Zhao
      Abstract: A versatile flexible piezoresistive sensor should maintain high sensitivity in a wide linear range, and provide a stable and repeatable pressure reading under bending. These properties are often difficult to achieve simultaneously with conventional filler–matrix composite active materials, as tuning of one material component often results in change of multiple sensor properties. Here, a material strategy is developed to realize a 3D graphene–poly(dimethylsiloxane) hollow structure, where the electrical conductivity and mechanical elasticity of the composite can be tuned separately by varying the graphene layer number and the poly(dimethylsiloxane) composition ratio, respectively. As a result, the sensor sensitivity and linear range can be easily improved through a decoupled tuning process, reaching a sensitivity of 15.9 kPa−1 in a 60 kPa linear region, and the sensor also exhibits fast response (1.2 ms rising time) and high stability. Furthermore, by optimizing the density of the graphene percolation network and thickness of the composite, the stability and repeatability of the sensor output under bending are improved, achieving a measurement error below 6% under bending radius variations from −25 to +25 mm. Finally, the potential applications of these sensors in wearable medical devices and robotic vision are explored.A 3D graphene–poly(dimethylsiloxane) hollow-structured composite is developed to independently tune the electrical and mechanical properties of the composite, thus allowing simultaneous improvement of both the sensitivity and linear range of the composite-based piezoresistive sensor. High reliability and repeatability of the sensor output under bending are achieved by optimizing the density of the percolation network and thickness of the hollow structure.
      PubDate: 2017-09-05T07:16:51.758461-05:
      DOI: 10.1002/adma.201702675
       
  • Ultrahigh-Efficiency Green PHOLEDs with a Voltage under 3 V and a Power
           Efficiency of Nearly 110 lm W−1 at Luminance of 10 000 cd m−2
    • Authors: Dongdong Zhang; Juan Qiao, Deqiang Zhang, Lian Duan
      Abstract: Maintaining high power efficiency (PE) under high brightness is still a pressing problem for the practical application of organic light-emitting diodes (OLEDs). Here, ultrahigh-efficiency green phosphorescent OLEDs (PHOLEDs) with a record-low voltage at luminance above 5000 cd m−2 are fabricated, by developing a novel anthracene/pyridine derivative as the electron-transporting material (ETM) combined with a material displaying thermally activated delayed fluorescence as the host. The pyridine units of the ETM not only facilitate charge injection, but also enhance the electron-transporting mobility, profiting from the closely packed molecules caused by the intermolecular H-bonding. The optimized green PHOLEDs show record-low driving voltages of 2.76 and 2.92 V, with EQEs/PEs of 28.0%/102 lm W−1 and 27.9%/97 lm W−1 at 5000 and 10 000 cd m−2, respectively. Furthermore, device optimization exhibits an unprecedented high PE of 109 lm W−1 at 10 000 cd m−2 with voltage under 3 V. Those values are the state-of-the-art among all reported green OLEDs so far, paving their way toward practical applications.Ultrahigh-efficiencygreen phosphorescent organic light-emitting diodes (PHOLEDs) with a voltage under 3 V and a power efficiency of nearly 110 lm W−1 at a luminance of 10 000 cd m−2 are developed by utilizing a novel anthracene/pyridine derivative as the electron-transporting material combined with a material displaying thermally activated delayed fluorescence as the host.
      PubDate: 2017-09-05T07:15:46.811809-05:
      DOI: 10.1002/adma.201702847
       
  • Bioinspired Redox-Active Catechol-Bearing Polymers as Ultrarobust Organic
           Cathodes for Lithium Storage
    • Authors: Nagaraj Patil; Abdelhafid Aqil, Farid Ouhib, Shimelis Admassie, Olle Inganäs, Christine Jérôme, Christophe Detrembleur
      Abstract: Redox-active catechols are bioinspired precursors for ortho-quinones that are characterized by higher discharge potentials than para-quinones, the latter being extensively used as organic cathode materials for lithium ion batteries (LIBs). Here, this study demonstrates that the rational molecular design of copolymers bearing catechol- and Li+ ion-conducting anionic pendants endow redox-active polymers (RAPs) with ultrarobust electrochemical energy storage features when combined to carbon nanotubes as a flexible, binder-, and metal current collector-free buckypaper electrode. The importance of the structure and functionality of the RAPs on the battery performances in LIBs is discussed. The structure-optimized RAPs can store high-capacities of 360 mA h g−1 at 5C and 320 mA h g−1 at 30C in LIBs. The high ion and electron mobilities within the buckypaper also enable to register 96 mA h g−1 (24% capacity retention) at an extreme C-rate of 600C (6 s for total discharge). Moreover, excellent cyclability is noted with a capacity retention of 98% over 3400 cycles at 30C. The high capacity, superior active-material utilization, ultralong cyclability, and excellent rate performances of RAPs-based electrode clearly rival most of the state-of-the-art Li+ ion organic cathodes, and opens up new horizons for large-scalable fabrication of electrode materials for ultrarobust Li storage.The facile combination of copolymers bearing redox-active catechols and Li+-ion-conducting groups with carbon nanotubes provides flexible binder- and metal-current-collector-free buckypaper composite cathodes for Li storage. Their high-capacity, ultralong cyclability, and excellent rate performances may open up new horizons in developing an economical and environmentally benign platform for large-scalable fabrication of electrode materials for ultrarobust Li storage.
      PubDate: 2017-09-04T07:46:06.21912-05:0
      DOI: 10.1002/adma.201703373
       
  • Highly Stretchable, Compliant, Polymeric Microelectrode Arrays for In Vivo
           Electrophysiological Interfacing
    • Authors: Dianpeng Qi; Zhiyuan Liu, Yan Liu, Ying Jiang, Wan Ru Leow, Mayank Pal, Shaowu Pan, Hui Yang, Yu Wang, Xiaoqian Zhang, Jiancan Yu, Bin Li, Zhe Yu, Wei Wang, Xiaodong Chen
      Abstract: Polymeric microelectrode arrays (MEAs) are emerging as a new generation of biointegrated microelectrodes to transduce original electrochemical signals in living tissues to external electrical circuits, and vice versa. So far, the challenge of stretchable polymeric MEAs lies in the competition between high stretchability and good electrode–substrate adhesion. The larger the stretchability, the easier the delamination of electrodes from the substrate due to the mismatch in their Young's modulus. In this work, polypyrrole (PPy) electrode materials are designed, with PPy nanowires integrated on the high conductive PPy electrode arrays. By utilizing this electrode material, for the first time, stretchable polymeric MEAs are fabricated with both high stretchability (≈100%) and good electrode–substrate adhesion (1.9 MPa). In addition, low Young's modulus (450 kPa), excellent recycling stability (10 000 cycles of stretch), and high conductivity of the MEAs are also achieved. As a proof of concept, the as-prepared polymeric MEAs are successfully used for conformally recording the electrocorticograph signals from rats in normal and epileptic states, respectively. Further, these polymeric MEAs are also successful in stimulating the ischiadic nerve of the rat. This strategy provides a new perspective to the highly stretchable and mechanically stable polymeric MEAs, which are vital for compliant neural electrodes.Compliant polymeric microelectrode arrays (MEAs) with both high stretchability and enhanced electrode–substrate adhesion are fabricated by taking advantage of wavy-structured electrodes and nanowire-based transition layers. Additionally, good recycling stability and high conductivity are also achieved. Finally, the as-prepared stretchable polymeric MEAs are successfully implanted for neural recording and stimulation.
      PubDate: 2017-09-04T07:42:03.810902-05:
      DOI: 10.1002/adma.201702800
       
  • Self-Powered Pulse Sensor for Antidiastole of Cardiovascular Disease
    • Authors: Han Ouyang; Jingjing Tian, Guanglong Sun, Yang Zou, Zhuo Liu, Hu Li, Luming Zhao, Bojing Shi, Yubo Fan, Yifan Fan, Zhong Lin Wang, Zhou Li
      Abstract: Cardiovascular diseases are the leading cause of death globally; fortunately, 90% of cardiovascular diseases are preventable by long-term monitoring of physiological signals. Stable, ultralow power consumption, and high-sensitivity sensors are significant for miniaturized wearable physiological signal monitoring systems. Here, this study proposes a flexible self-powered ultrasensitive pulse sensor (SUPS) based on triboelectric active sensor with excellent output performance (1.52 V), high peak signal-noise ratio (45 dB), long-term performance (107 cycles), and low cost price. Attributed to the crucial features of acquiring easy-processed pulse waveform, which is consistent with second derivative of signal from conventional pulse sensor, SUPS can be integrated with a bluetooth chip to provide accurate, wireless, and real-time monitoring of pulse signals of cardiovascular system on a smart phone/PC. Antidiastole of coronary heart disease, atrial septal defect, and atrial fibrillation are made, and the arrhythmia (atrial fibrillation) is indicative diagnosed from health, by characteristic exponent analysis of pulse signals accessed from volunteer patients. This SUPS is expected to be applied in self-powered, wearable intelligent mobile diagnosis of cardiovascular disease in the future.A flexible self-powered ultrasensitive pulse sensor (SUPS) based on a triboelectric active sensor is proposed. SUPS can provide accurate, wireless, and real-time monitoring of pulse signals of a cardiovascular system on a smart phone/PC. Different types of cardiovascular patients are indicatively diagnosed from health. This SUPS is expected to be applied in intelligent mobile diagnosis of cardiovascular disease in the future.
      PubDate: 2017-09-01T14:38:27.34025-05:0
      DOI: 10.1002/adma.201703456
       
  • Ultrasensitive and Fast All-Inorganic Perovskite-Based Photodetector via
           Fast Carrier Diffusion
    • Authors: Bin Yang; Fengying Zhang, Junsheng Chen, Songqiu Yang, Xusheng Xia, Tõnu Pullerits, Weiqiao Deng, Keli Han
      Abstract: Low trap-state density, high carrier mobility, and efficient charge carrier collection are key parameters for photodetectors with high sensitivity and fast response time. This study demonstrates a simple solution growth method to prepare CsPbBr3 microcrystals (MCs) with low trap-state density. Time-dependent photoluminescence study with one-photon excitation (OPE) and two-photon excitation (TPE) indicates that CsPbBr3 MCs exhibit fast carrier diffusion with carrier mobility over 100 cm2 V−1 S−1. Furthermore, CsPbBr3 MC-based photodetectors with high charge carriers' collection efficiency are fabricated. Such photodetectors show ultrahigh responsivity (R) up to 6 × 104 A W−1 with OPE and high R up to 6 A W−1 with TPE. The R for OPE is over one order of magnitude higher (the R for TPE is three orders of magnitude higher) than that of previously reported all-inorganic perovskite-based photodetectors. Moreover, the photodetectors exhibit fast response time of ≈1 ms, which corresponds to a gain ≈105 and a gain- bandwidth product of 108 Hz for OPE (a gain ≈103 and a gain-bandwidth product of 106 Hz for TPE).CsPbBr3 microcrystal (MC)-based photodetectors exhibit ultrahigh responsivity (R) up to 6 × 104 A W−1 with one-photon excitation and R = 6 A W−1 with two-photon excitation. The photodetectors also exhibit fast response time of ≈1 ms. The sensitive and fast photoresponse is ascribed to the large absorption coefficient, low trap-state density, and high carrier mobility of CsPbBr3 MCs.
      PubDate: 2017-09-01T14:36:42.652114-05:
      DOI: 10.1002/adma.201703758
       
  • Half-Metallic Behavior in 2D Transition Metal Dichalcogenides Nanosheets
           by Dual-Native-Defects Engineering
    • Authors: Yun Tong; Yuqiao Guo, Kejun Mu, Huan Shan, Jun Dai, Yi Liu, Zhe Sun, Aidi Zhao, Xiao Cheng Zeng, Changzheng Wu, Yi Xie
      Abstract: Two-dimensional transition metal dichalcogenides (TMDs) have been regarded as one of the best nonartificial low-dimensional building blocks for developing spintronic nanodevices. However, the lack of spin polarization in the vicinity of the Fermi surface and local magnetic moment in pristine TMDs has greatly hampered the exploitation of magnetotransport properties. Herein, a half-metallic structure of TMDs is successfully developed by a simple chemical defect-engineering strategy. Dual native defects decorate titanium diselenides with the coexistence of metal-Ti-atom incorporation and Se-anion defects, resulting in a high-spin-polarized current and local magnetic moment of 2D Ti-based TMDs toward half-metallic room-temperature ferromagnetism character. Arising from spin-polarization transport, the as-obtained T-TiSe1.8 nanosheets exhibit a large negative magnetoresistance phenomenon with a value of −40% (5T, 10 K), representing one of the highest negative magnetoresistance effects among TMDs. It is anticipated that this dual regulation strategy will be a powerful tool for optimizing the intrinsic physical properties of TMD systems.A dual-native-defects (Ti atom self-doping and Se defects) engineering strategy is proposed to introduce a spin polarized current and local magnetic moment into 2D nonmagnetic TiSe2, bringing half-metallic behavior with larger negative magnetoresistance.
      PubDate: 2017-09-01T01:02:56.084228-05:
      DOI: 10.1002/adma.201703123
       
  • Highly Concentrated, Ultrathin Nickel Hydroxide Nanosheet Ink for Wearable
           Energy Storage Devices
    • Authors: Peipei Shi; Rong Chen, Li Hua, Li Li, Ruyi Chen, Yujiao Gong, Chenyang Yu, Jinyuan Zhou, Bin Liu, Gengzhi Sun, Wei Huang
      Abstract: Solution-based techniques are considered as a promising strategy for scalable fabrication of flexible electronics owing to their low-cost and high processing speed. The key to the success of these techniques is dominated by the ink formulation of active nanomaterials. This work successfully prepares a highly concentrated two dimensional (2D) crystal ink comprised of ultrathin nickel hydroxide (Ni(OH)2) nanosheets with an average lateral size of 34 nm. The maximum concentration of Ni(OH)2 nanosheets in water without adding any additives reaches as high as 50 mg mL−1, which can be printed on arbitrary substrates to form Ni(OH)2 thin films. As a proof-of-concept application, Ni(OH)2 nanosheet ink is coated on commercialized carbon fiber yarns to fabricate wearable energy storage devices. The thus-fabricated hybrid supercapacitors exhibit excellent flexibility with a capacitance retention of 96% after 5000 bending–unbending cycles, and good weavability with a high volumetric capacitance of 36.3 F cm−3 at a current density of 0.4 A cm−3, and an energy density of 11.3 mWh cm−3 at a power density of 0.3 W cm−3. As a demonstration of practical application, a red light emitting diode can be lighted up by three hybrid devices connected in series.A highly concentrated 2D crystal ink comprised of ultrathin Ni(OH)2 nanosheets with an average lateral size of 34 nm is prepared. The Ni(OH)2 nanosheet ink can be printed on commercialized carbon fiber yarn for wearable energy storage devices. The thus-fabricated hybrid supercapacitors exhibit good flexibility and weavability with much improved capacitance and energy density.
      PubDate: 2017-09-01T01:02:02.843414-05:
      DOI: 10.1002/adma.201703455
       
  • Twinned Growth of Metal-Free, Triazine-Based Photocatalyst Films as
           Mixed-Dimensional (2D/3D) van der Waals Heterostructures
    • Authors: Dana Schwarz; Yu Noda, Jan Klouda, Karolina Schwarzová-Pecková, Ján Tarábek, Jiří Rybáček, Jiří Janoušek, Frank Simon, Maksym V. Opanasenko, Jiří Čejka, Amitava Acharjya, Johannes Schmidt, Sören Selve, Valentin Reiter-Scherer, Nikolai Severin, Jürgen P. Rabe, Petra Ecorchard, Junjie He, Miroslav Polozij, Petr Nachtigall, Michael J. Bojdys
      Abstract: Design and synthesis of ordered, metal-free layered materials is intrinsically difficult due to the limitations of vapor deposition processes that are used in their making. Mixed-dimensional (2D/3D) metal-free van der Waals (vdW) heterostructures based on triazine (C3N3) linkers grow as large area, transparent yellow-orange membranes on copper surfaces from solution. The membranes have an indirect band gap (Eg,opt = 1.91 eV, Eg,elec = 1.84 eV) and are moderately porous (124 m2 g−1). The material consists of a crystalline 2D phase that is fully sp2 hybridized and provides structural stability, and an amorphous, porous phase with mixed sp2–sp hybridization. Interestingly, this 2D/3D vdW heterostructure grows in a twinned mechanism from a one-pot reaction mixture: unprecedented for metal-free frameworks and a direct consequence of on-catalyst synthesis. Thanks to the efficient type I heterojunction, electron transfer processes are fundamentally improved and hence, the material is capable of metal-free, light-induced hydrogen evolution from water without the need for a noble metal cocatalyst (34 µmol h−1 g−1 without Pt). The results highlight that twinned growth mechanisms are observed in the realm of “wet” chemistry, and that they can be used to fabricate otherwise challenging 2D/3D vdW heterostructures with composite properties.Mixed-dimensional (2D/3D) layered, van der Waals heterostructures based on triazine linkers are produced in a facile, one-pot, “wet” chemistry process. Macroscopic films of the material grow via a twinned mechanism—first, the 2D crystalline phase, then the 3D polymer—on a copper support that acts both as a catalyst and template, and form an efficient type I heterojunction.
      PubDate: 2017-08-31T11:11:55.887538-05:
      DOI: 10.1002/adma.201703399
       
  • Side Chain Engineering on Medium Bandgap Copolymers to Suppress Triplet
           Formation for High-Efficiency Polymer Solar Cells
    • Authors: Lingwei Xue; Yankang Yang, Jianqiu Xu, Chunfeng Zhang, Haijun Bin, Zhi-Guo Zhang, Beibei Qiu, Xiaojun Li, Chenkai Sun, Liang Gao, Jia Yao, Xiaofeng Chen, Yunxu Yang, Min Xiao, Yongfang Li
      Abstract: Suppression of carrier recombination is critically important in realizing high-efficiency polymer solar cells. Herein, it is demonstrated difluoro-substitution of thiophene conjugated side chain on donor polymer can suppress triplet formation for reducing carrier recombination. A new medium bandgap 2D-conjugated D–A copolymer J91 is designed and synthesized with bi(alkyl-difluorothienyl)-benzodithiophene as donor unit and fluorobenzotriazole as acceptor unit, for taking the advantages of the synergistic fluorination on the backbone and thiophene side chain. J91 demonstrates enhanced absorption, low-lying highest occupied molecular orbital energy level, and higher hole mobility, in comparison with its control polymer J52 without fluorination on the thiophene side chains. The transient absorption spectra indicate that J91 can suppress the triplet formation in its blend film with n-type organic semiconductor acceptor m-ITIC (3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone)-5,5,11,11-tetrakis(3-hexylphenyl)-dithieno[2,3-d:2,3′-d′]-s-indaceno[1,2-b:5,6-b′]-dithiophene). With these favorable properties, a higher power conversion efficiency of 11.63% with high VOC of 0.984 V and high JSC of 18.03 mA cm−2 is obtained for the polymer solar cells based on J91/m-ITIC with thermal annealing. The improved photovoltaic performance by thermal annealing is explained from the morphology change upon thermal annealing as revealed by photoinduced force microscopy. The results indicate that side chain engineering can provide a new solution to suppress carrier recombination toward high efficiency, thus deserves further attention.Suppression of carrier recombination is critically important for efficient polymer solar cells. Herein, it is demonstrated that difluoro-substitution of thiophene-conjugated side chains on the medium-bandgap polymer donor can suppress triplet formation for reducing carrier recombination and improving photovoltaic performance.
      PubDate: 2017-08-31T11:11:17.72229-05:0
      DOI: 10.1002/adma.201703344
       
  • Robust Fe3Mo3C Supported IrMn Clusters as Highly Efficient Bifunctional
           Air Electrode for Metal–Air Battery
    • Authors: Zhiming Cui; Yutao Li, Gengtao Fu, Xiang Li, John B. Goodenough
      Abstract: Catalysts at the air cathode for oxygen reduction and evolution reactions are central to the stability of rechargeable metal–air batteries, an issue that is gaining increasing interest in recent years. Herein, a highly durable and efficient carbide-based bifunctional catalyst consisting of iron–molybdenum carbide (Fe3Mo3C) and IrMn nanoalloys is demonstratred. This carbide is chemically stable in alkaline media and over the potential range of an air cathode. More importantly, Fe3Mo3C is very active for oxygen reduction reaction (ORR) in alkaline media. Fe3Mo3C supported IrMn as a bifunictional catalysts exhibits superior catalytic performance than the state of the art ORR catalyst (Pt/C) and the oxygen evolution reaction catalyst (Ir/C). IrMn/Fe3Mo3C enables Zn–air batteries to achieve long-term cycling performance over 200 h with high efficiency. The extraordinarily high performance of IrMn/Fe3Mo3C bifunictional catalyst provides a very promising alternative to the conventional Pt/C and Ir/C catalyst for an air cathode in alkaline electrolyte.An efficient and cost-effective IrMn/Fe3Mo3C bifunctional catalyst is demonstrated that enables a Zn–air battery to achieve long-term cycling performance over 200 h with high efficiency.
      PubDate: 2017-08-30T03:06:36.161012-05:
      DOI: 10.1002/adma.201702385
       
  • Integration of Graphene, Nano Sulfur, and Conducting Polymer into Compact,
           Flexible Lithium–Sulfur Battery Cathodes with Ultrahigh Volumetric
           Capacity and Superior Cycling Stability for Foldable Devices
    • Authors: Peitao Xiao; Fanxing Bu, Guanhui Yang, Yu Zhang, Yuxi Xu
      Abstract: Lithium–sulfur batteries, as one of the most promising next-generation batteries, attract tremendous attentions due to their high energy density and low cost. However, their practical application is hindered by their short cycling life and low volumetric capacity. Herein, compact, flexible, and free-standing films with a sandwich structure are designed simply by vacuum filtration, in which nanosulfur is homogenously coated by graphene and poly(3,4-ethylene-dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). This unique hierarchical structure not only provides a highly conductive network and intimate contacts between nanosulfur and graphene/PEDOT:PSS for effective charge transportation, but also offers synergistic physical restriction and chemical confinement of dissoluble intermediate lithium polysulfides during electrochemical processes. Therefore, these conductive compact films, used directly as cathodes, show the highest reversible volumetric capacity of 1432 Ah L−1 at 0.1 C and 1038 Ah L−1 at 1 C, and excellent cycling stability with a minimal decay rate of 0.04% per cycle over 500 cycles at 1 C. Meanwhile, remarkable rate performance with a high capacity of 701 mAh g−1 at 4 C is also achieved. Soft-packaged batteries based on this flexible cathode are further fabricated and demonstrate excellent mechanical and electrochemical properties with little capacity decay under folded state, highlighting the practical application of our deliberately designed electrode in a flexible power system.A novel compact and flexible film with sandwich structure integrated with graphene, nanosulfur, and poly(3,4-ethylene-dioxythiophene):poly(styrenesulfonate) is synthesized simply by vacuum filtration. The free-standing film can be used directly as cathodes for lithium–sulfur coin cell batteries with a highest volumetric capacity and long-term cycling stability, and high-performance soft-packaged batteries.
      PubDate: 2017-08-30T03:06:16.087092-05:
      DOI: 10.1002/adma.201703324
       
  • Giant Incident Photon-to-Current Conversion with Photoconductivity Gain on
           Nanostructured Bismuth Oxysulfide Photoelectrodes under Visible-Light
           Illumination
    • Authors: Evgeny A. Bondarenko; Eugene A. Streltsov, Mikalai V. Malashchonak, Alexander V. Mazanik, Anatoly I. Kulak, Ekaterina V. Skorb
      Abstract: Nanostructured layered bismuth oxysulfide films synthesized by chemical bath deposition reveal a giant incident photon-to-current conversion efficiency (IPCE). This study shows that surprisingly for the cathodic photocurrent in the photoreduction process, the IPCE reaches ≈2500% in aqueous solutions containing [Fe(CN)6]3−. The giant IPCE is observed starting from a certain minimal oxidizer concentration (c> 10−3m for [Fe(CN)6]3−) and decreases nonlinearly with an increase of illumination intensity. Giant IPCE is determined by the decrease in resistivity of the bismuth oxysulfide film under illumination with photoconductivity gain, which provides the possibility of charge carriers from an external circuit to participate in the photoreduction process. Giant IPCE is observed not only in [Fe(CN)6]3− solutions, but also in electrolytes containing other photoelectron acceptors: Fe3+, I3−, quinone, H2O2. In all, solution-processed layered bismuth oxysulfide films offer large-area coverage, nontoxicity, low cost, and compatibility with a wide range of substrates. Abnormally high photoelectrochemical activity, as well as a band gap energy value favorable for efficient conversion of solar light (1.38 eV, direct optical transitions), proves the potential of bismuth oxysulfide photoelectrodes for a new generation of high-performance photoconverters.A surprisingly giant incident photon-to-current conversion efficiency—about 2500%—is shown for the cathodic photocurrent in aqueous solutions containing photoelectron acceptors. Abnormally high photoelectrochemical activity, as well as a band gap energy value favorable for efficient conversion of solar light (1.38 eV, direct optical transitions), proves the potential of bismuth oxysulfide photoelectrodes for a new generation of high-performance photoconverters.
      PubDate: 2017-08-29T03:15:44.629351-05:
      DOI: 10.1002/adma.201702387
       
  • Water-Enabled Healing of Conducting Polymer Films
    • Authors: Shiming Zhang; Fabio Cicoira
      Abstract: The conducting polymer polyethylenedioxythiophene doped with polystyrene sulfonate (PEDOT:PSS) has become one of the most successful organic conductive materials due to its high air stability, high electrical conductivity, and biocompatibility. In recent years, a great deal of attention has been paid to its fundamental physicochemical properties, but its healability has not been explored in depth. This communication reports the first observation of mechanical and electrical healability of PEDOT:PSS thin films. Upon reaching a certain thickness (about 1 µm), PEDOT:PSS thin films damaged with a sharp blade can be electrically healed by simply wetting the damaged area with water. The process is rapid, with a response time on the order of 150 ms. Significantly, after being wetted the films are transformed into autonomic self-healing materials without the need of external stimulation. This work reveals a new property of PEDOT:PSS and enables its immediate use in flexible and biocompatible electronics, such as electronic skin and bioimplanted electronics, placing conducting polymers on the front line for healing applications in electronics.Films of the conducting polymer polyethylenedioxythiophene doped with polystyrene sulfonate (PEDOT:PSS) can be rapidly healed after multiple damages upon the addition of water. The healed damage can be much larger than the film thickness. Films wet with water act as autonomic self-healing conductors. Healable PEDOT:PSS films can be exploited for electronic skin, self-healing circuits, water-enabled sensors, and wearable electronics.
      PubDate: 2017-08-28T05:36:21.487722-05:
      DOI: 10.1002/adma.201703098
       
  • High-Resolution Spin-on-Patterning of Perovskite Thin Films for a
           Multiplexed Image Sensor Array
    • Authors: Woongchan Lee; Jongha Lee, Huiwon Yun, Joonsoo Kim, Jinhong Park, Changsoon Choi, Dong Chan Kim, Hyunseon Seo, Hakyong Lee, Ji Woong Yu, Won Bo Lee, Dae-Hyeong Kim
      Abstract: Inorganic–organic hybrid perovskite thin films have attracted significant attention as an alternative to silicon in photon-absorbing devices mainly because of their superb optoelectronic properties. However, high-definition patterning of perovskite thin films, which is important for fabrication of the image sensor array, is hardly accomplished owing to their extreme instability in general photolithographic solvents. Here, a novel patterning process for perovskite thin films is described: the high-resolution spin-on-patterning (SoP) process. This fast and facile process is compatible with a variety of spin-coated perovskite materials and perovskite deposition techniques. The SoP process is successfully applied to develop a high-performance, ultrathin, and deformable perovskite-on-silicon multiplexed image sensor array, paving the road toward next-generation image sensor arrays.A high-resolution, high-definition patterning method of perovskite thin films is reported. The patterning method (spin-on-patterning) is based on wetting/dewetting behavior of perovskite precursor solution during the spin-coating process. This fast and facile process is compatible with various solution-processing perovskite deposition techniques. By using this method, a high-performance, ultrathin, and deformable perovskite-on-silicon multiplexed image sensor array is successfully achieved.
      PubDate: 2017-08-28T05:30:25.401017-05:
      DOI: 10.1002/adma.201702902
       
  • Superior Photocatalytic H2 Production with Cocatalytic Co/Ni Species
           Anchored on Sulfide Semiconductor
    • Authors: Guixia Zhao; Yubin Sun, Wei Zhou, Xiangke Wang, Kun Chang, Guigao Liu, Huimin Liu, Tetsuya Kako, Jinhua Ye
      Abstract: Downsizing transition metal-based cocatalysts on semiconductors to promote photocatalytic efficiency is important for research and industrial applications. This study presents a novel and facile strategy for anchoring well-dispersed metal species on CdS surface through controlled decarboxylation of the ethylenediaminetetraacetate (EDTA) ligand in the metal–EDTA (M–EDTA) complex and CdS mixture precursor to function as a cocatalyst in the photocatalytic H2 evolution. Microstructure characterization and performance evaluation reveal that under visible light the resulting pentacoordinated Co(II) and hexacoordinated Ni(II) on CdS exhibits a high activity of 3.1 mmol h−1 (with turnover frequency (TOF) of 626 h−1 and apparent quantum efficiency (AQE) of 56.2% at 420 nm) and 4.3 mmol h−1 (with TOF of 864 h−1 and AQE of 67.5% at 420 nm), respectively, toward cocatalytic hydrogen evolution, and the cocatalytic activity of such a hexacoordinated Ni(II) even exceeds that of platinum. Further mechanistic study and theoretical modeling indicate that the fully utilized Co(II)/Ni(II) active sites, efficient charge transfer, and favorable kinetics guarantee the efficient activities. This work introduces a promising precursor, i.e., M–EDTA for planting well-dispersed transition metal species on the sulfide supports by a facile wet-chemistry approach, providing new opportunities for photocatalytic H2 production at the atomic/molecular scale.Well-dispersed Co(II) species with pentacoordination and Ni(II) species with hexacoordination are anchored on a CdS surface by using a metal–ethylenediaminetetraacetate complex as a precursor, both of which function as efficient cocatalysts in photocatalytic H2 evolution, with the activity of the Ni(II) species even exceeding that of platinum, with an apparent quantum efficiency of 67.5% at 420 nm.
      PubDate: 2017-08-25T11:12:06.020687-05:
      DOI: 10.1002/adma.201703258
       
  • 1D Coordination Polymer Nanofibers for Low-Temperature Photothermal
           Therapy
    • Authors: Yu Yang; Wenjun Zhu, Ziliang Dong, Yu Chao, Lai Xu, Meiwan Chen, Zhuang Liu
      Abstract: Near-infrared (NIR)-light-triggered photothermal therapy (PTT) usually requires hyperthermia to>50 °C for effective tumor ablation, which can potentially induce inflammatory disease and heating damage of normal organs nearby, while tumor lesions without sufficient heating (e.g., the internal part) may survive after treatment. Achieving effective tumor killing under relatively low temperatures is thus critical toward successful clinical use of PTT. Herein, we design a simple strategy to fabricate poly(ethylene glycol) (PEG)-modified one-dimensional nanoscale coordination polymers (1D-NCPs) with intrinsic biodegradability, large surface area, pH-responsive behaviors, and versatile theranostic functions. With NCPs consisting of Mn2+/indocyanine green (ICG) as the example, Mn-ICG@pHis-PEG display efficient pH-responsive tumor retention after systemic administration and then load Gambogic acid (GA), a natural inhibitor of heat-shock protein 90 (Hsp90) that plays an essential role for cells to resist heating-induced damage. Such Mn-ICG@pHis-PEG/GA under a mild NIR-triggered heating is able to induce effective apoptosis of tumor cells, realizing low-temperature PTT (~43 °C) with excellent tumor destruction efficacy. This work not only develops a facile approach to fabricate PEGylated 1D-NCPs with tumor-specific pH responsiveness and theranostic functionalities, but also presents a unique low-temperature PTT strategy to kill cancer in a highly effective and minimally invasive manner.A one-dimensional (1D) PEGylated nanoscale coordination polymer (NCP) is fabricated via a one-step method. After loading gambogic acid (GA), such Mn-ICG@pHis-PEG/GA displays efficient pH-responsive tumor retention after systemic administration. Owing to the GA-induced down-regulation of Hsp90 to overcome the thermal-resistance of tumor cells, highly effective in vivo destruction of tumors is relized with Mn-ICG@pHis-PEG/GA under low-temperature photothermal therapy at 43 °C.
      PubDate: 2017-08-21T09:23:24.579639-05:
      DOI: 10.1002/adma.201703588
       
  • Molybdenum Oxides – From Fundamentals to Functionality
    • Authors: Isabela Alves de Castro; Robi Shankar Datta, Jian Zhen Ou, Andres Castellanos-Gomez, Sharath Sriram, Torben Daeneke, Kourosh Kalantar-zadeh
      Abstract: The properties and applications of molybdenum oxides are reviewed in depth. Molybdenum is found in various oxide stoichiometries, which have been employed for different high-value research and commercial applications. The great chemical and physical characteristics of molybdenum oxides make them versatile and highly tunable for incorporation in optical, electronic, catalytic, bio, and energy systems. Variations in the oxidation states allow manipulation of the crystal structure, morphology, oxygen vacancies, and dopants, to control and engineer electronic states. Despite this overwhelming functionality and potential, a definitive resource on molybdenum oxide is still unavailable. The aim here is to provide such a resource, while presenting an insightful outlook into future prospective applications for molybdenum oxides.Molybdenum is found in various oxide stoichiometries, which have been employed for different high-value research and commercial applications. The variations in oxidation states allow the manipulation of crystal structure, morphology, oxygen vacancies, and dopants, to control and engineer the electronic states, which makes them versatile and highly tunable for incorporation in optical, electronic, catalytic, bio, and energy systems.
      PubDate: 2017-08-16T07:30:34.073668-05:
      DOI: 10.1002/adma.201701619
       
  • Metallic MXene Saturable Absorber for Femtosecond Mode-Locked Lasers
    • Authors: Young In Jhon; Joonhoi Koo, Babak Anasori, Minah Seo, Ju Han Lee, Yury Gogotsi, Young Min Jhon
      Abstract: 2D transition metal carbides, nitrides, and carbonitides called MXenes have attracted much attention due to their outstanding properties. However, MXene's potential in laser technology is not explored. It is demonstrated here that Ti3CN, one of MXene compounds, can serve as an excellent mode-locker that can produce femtosecond laser pulses from fiber cavities. Stable laser pulses with a duration as short as 660 fs are readily obtained at a repetition rate of 15.4 MHz and a wavelength of 1557 nm. Density functional theory calculations show that Ti3CN is metallic, in contrast to other 2D saturable absorber materials reported so far to be operative for mode-locking. 2D structural and electronic characteristics are well conserved in their stacked form, possibly due to the unique interlayer coupling formed by MXene surface termination groups. Noticeably, the calculations suggest a promise of MXenes in broadband saturable absorber applications due to metallic characteristics, which agrees well with the experiments of passively Q-switched lasers using Ti3CN at wavelengths of 1558 and 1875 nm. This study provides a valuable strategy and intuition for the development of nanomaterial-based saturable absorbers opening new avenues toward advanced photonic devices based on MXenes.A metallic 2D material, Ti3CN MXene, is demonstrated to be an excellent mode-locker for femtosecond laser generation regardless of stacking. Ti3CN also shows promise in broadband saturable absorber applications due to metallic characteristics. It is inferred that the 2D nature and unique stacking of Ti3CN are responsible for these outstanding results that can hardly be achieved in the 3D metallic regime.
      PubDate: 2017-07-17T01:53:30.528202-05:
      DOI: 10.1002/adma.201702496
       
 
 
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