Advanced Materials

Cover image for Vol. 22 Issue 46

December 7, 2010

Volume 22, Issue 46

Pages 5219–5317

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Correction
    6. Progress Report
    7. Communications
    8. Research News
    1. Graphene Electronics: High-Gain Graphene-Titanium Oxide Photoconductor Made from Inkjet Printable Ionic Solution (Adv. Mater. 46/2010) (page 5219)

      Kiran Kumar Manga, Shuai Wang, Manu Jaiswal, Qiaoliang Bao and Kian Ping Loh

      Version of Record online: 9 DEC 2010 | DOI: 10.1002/adma.201090154

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      A solution-processible approach to fabricating hybrid TiO2-graphene photoconducting matrices that are printable and spin-castable is reported on p. 5265 by Kian Ping Loh and co-workers. The technique produces extended heterojunctions of TiO2 and graphene, permitting short collection paths for electrons. Such a solution-based approach affords chemical tunability and easy film formation, and holds considerable innovation potential for carbon-based printable optoelectronic devices.

  2. Inside Front Cover

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Correction
    6. Progress Report
    7. Communications
    8. Research News
    1. Stem Cells: Patterned Differentiation of Individual Embryoid Bodies in Spatially Organized 3D Hybrid Microgels (Adv. Mater. 46/2010) (page 5220)

      Hao Qi, Yanan Du, Lianyong Wang, Hirokazu Kaji, Hojae Bae and Ali Khademhosseini

      Version of Record online: 9 DEC 2010 | DOI: 10.1002/adma.201090153

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      A microengineered hybrid hydrogel containing asymmetrical extracellular matrices is developed to mimic anisotropic stem cell niches, in work reported by Ali Khademhosseini and co-workers on p. 5276. The reconstructed artificial asymmetrical extracellular matrix enables thorough investigation of spatially regulated embryonic development without exogenous factors. This technique may be a powerful platform for further understanding and engineering of stem cells in controlled environments.

  3. Contents

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Correction
    6. Progress Report
    7. Communications
    8. Research News
  4. Correction

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Correction
    6. Progress Report
    7. Communications
    8. Research News
    1. You have free access to this content
      Correction: Graphene and Graphene Oxide: Synthesis, Properties, and Applications (page 5226)

      Yanwu Zhu, Shanthi Murali, Weiwei Cai, Xuesong Li, Ji Won Suk, Jeffrey R. Potts and Rodney S. Ruoff

      Version of Record online: 9 DEC 2010 | DOI: 10.1002/adma.201090156

      This article corrects:

      Graphene and Graphene Oxide: Synthesis, Properties, and Applications

      Vol. 22, Issue 35, 3906–3924, Version of Record online: 29 JUN 2010

  5. Progress Report

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Correction
    6. Progress Report
    7. Communications
    8. Research News
    1. Recent Developments in Top-Emitting Organic Light-Emitting Diodes (pages 5227–5239)

      Shufen Chen, Lingling Deng, Jun Xie, Ling Peng, Linghai Xie, Quli Fan and Wei Huang

      Version of Record online: 14 SEP 2010 | DOI: 10.1002/adma.201001167

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      Recent developments in top-emitting organic light-emitting diodes (TEOLEDs) are reviewed, with emphasis on their significant advantages which include high resolution and large aperture ratio in full-color display applications. After a brief introduction to TEOLEDs, typical microcavity theory and design conceptions of monochromatic (red, green, blue) and white TEOLEDs and their applications are summarized.

  6. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Correction
    6. Progress Report
    7. Communications
    8. Research News
    1. An Easily Synthesized Blue Polymer for High-Performance Polymer Solar Cells (pages 5240–5244)

      Ergang Wang, Lintao Hou, Zhongqiang Wang, Stefan Hellström, Fengling Zhang, Olle Inganäs and Mats R. Andersson

      Version of Record online: 8 SEP 2010 | DOI: 10.1002/adma.201002225

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      High performance solar cells fabricated from an easily synthesized donor-acceptor polymer show maximum power point up to 6.0 mW cm−2, with an open-circuit voltage of 0.89 V, short-circuit current density of 10.5 mA cm−2 and fill factor of 0.64, making this polymer a particularly promising candidate for high-efficiency low-cost polymer solar cells.

    2. Barrier Properties of Synthetic Clay with a Kilo-Aspect Ratio (pages 5245–5249)

      Michael W. Möller, Thomas Lunkenbein, Hussein Kalo, Martin Schieder, Daniel A. Kunz and Josef Breu

      Version of Record online: 13 SEP 2010 | DOI: 10.1002/adma.201002559

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      A lithium-fluorohectorite was prepared and tested in respect to its performance as a barrier-forming material. To emphasize the supremacy of this material as compared to commercially available clays like Cloisite Na+, Optigel SH, or Microlite 963, we determined the oxygen transmission of binderless clay-films. Furthermore, special emphasis was placed on optical transparency.

    3. Interfacial Recombination for Fast Operation of a Planar Organic/QD Infrared Photodetector (pages 5250–5254)

      Timothy P. Osedach, Ni Zhao, Scott M. Geyer, Liang-Yi Chang, Darcy D. Wanger, Alexi C. Arango, Moungi C. Bawendi and Vladimir Bulović

      Version of Record online: 28 SEP 2010 | DOI: 10.1002/adma.201002589

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      A planar infrared photodetector consisting of discrete films of PbS quantum dots (QDs) and the fullerene derivative, PCBM, is reported. A fast recombination process at the PbS QD/PCBM interface enables an improvement in the response speed of greater than two orders-of-magnitude over devices consisting only of the QD film. The physical processes governing device operation and performance are explored.

    4. Templating Synthesis of Preloaded Doxorubicin in Hollow Mesoporous Silica Nanospheres for Biomedical Applications (pages 5255–5259)

      Yang Zhao, Li-Ning Lin, Yang Lu, Shao-Feng Chen, Liang Dong and Shu-Hong Yu

      Version of Record online: 22 OCT 2010 | DOI: 10.1002/adma.201002395

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      Hollow mesoporous silica (HMS) spheres preloaded with the anticancer drug Doxorubicin (DOX) can be synthesized by using porous CaCO3 spheres as templates (see figure). With good biocompatibility, the HMS@DOX spheres exhibit a greatly enhanced therapeutic effect towards tumor cells ; this enhancement may be caused by the efficient protection of DOX and the pH-sensitive release of DOX, together with enhanced intracellular delivery.

    5. Fabrication of FeF3 Nanoflowers on CNT Branches and Their Application to High Power Lithium Rechargeable Batteries (pages 5260–5264)

      Sung-Wook Kim, Dong-Hwa Seo, Hyeokjo Gwon, Jongsoon Kim and Kisuk Kang

      Version of Record online: 15 OCT 2010 | DOI: 10.1002/adma.201002879

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      Nanoarchitectures composed of FeF3 nanoflowers on carbon nanotube (CNT) branches (FNCB, see figure) are fabricated by functionalization of CNT surfaces with FeF3. FNCB’s improved Li-ion and electron transport makes it a candidate for applications in cathode material for lithium rechargeable batteries.

    6. High-Gain Graphene-Titanium Oxide Photoconductor Made from Inkjet Printable Ionic Solution (pages 5265–5270)

      Kiran Kumar Manga, Shuai Wang, Manu Jaiswal, Qiaoliang Bao and Kian Ping Loh

      Version of Record online: 26 OCT 2010 | DOI: 10.1002/adma.201002939

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      TiO2- graphene photoconducting films can be easily prepared by inkjet printing from a precursor solution of graphene oxide and titanium (IV) bis(ammonium lactate) dihydroxide. Photoconductor devices fabricated from these films exhibit wide-band photoconductivity, high photodetectivity and photoconductive gain, and a faster photoresponse compared to TiO2-only photodetectors.

    7. Collective Cell Migration on Artificial Extracellular Matrix Proteins Containing Full-Length Fibronectin Domains (pages 5271–5275)

      Eileen Fong and David A. Tirrell

      Version of Record online: 30 SEP 2010 | DOI: 10.1002/adma.201002448

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      Protein-based biomaterials that promote rapid wound healing are prepared by expression of artificial genes in bacterial cells. Artificial extracellular matrix proteins containing full-length fibronectin domains 9 and 10 exhibit strong α5β1 integrin binding and support rapid spreading, proliferation, and collective migration of fibroblasts.

    8. Patterned Differentiation of Individual Embryoid Bodies in Spatially Organized 3D Hybrid Microgels (pages 5276–5281)

      Hao Qi, Yanan Du, Lianyong Wang, Hirokazu Kaji, Hojae Bae and Ali Khademhosseini

      Version of Record online: 13 OCT 2010 | DOI: 10.1002/adma.201002873

      Thumbnail image of graphical abstract

      A microengineered hybrid hydrogel array is developed containing asymmetrical extracellular matrices [polyethylene-glycol (PEG) and gelatin methacrylate (GelMA)] to mimic the anisotropic stem cell niche and induce the patterned differentiation of embryoid bodies (EBs). The asymmetrical matrices around individual aggregate of mouse EBs induce polarity and demonstrate the potential of microscale engineered materials for forming tissues.

    9. Silver Clusters Embedded in Glass as a Perennial High Capacity Optical Recording Medium (pages 5282–5286)

      Arnaud Royon, Kevin Bourhis, Matthieu Bellec, Gautier Papon, Bruno Bousquet, Yannick Deshayes, Thierry Cardinal and Lionel Canioni

      Version of Record online: 19 OCT 2010 | DOI: 10.1002/adma.201002413

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      Three-dimensional optical recording by laser-induced fluorescent silver clusters is demonstrated in glass. The fluorescence properties of these stable clusters can be altered, depending on the glass recording exposure conditions. A “Blu-ray”-like drive enables readout of the information inside the glass without cross-talk and photobleaching (see figure). This original recording medium can provide an answer to the societal problem of long-term high-density data storage.

    10. Analysis of Charge Photogeneration as a Key Determinant of Photocurrent Density in Polymer: Fullerene Solar Cells (pages 5287–5291)

      Tracey M. Clarke, Amy Ballantyne, Safa Shoaee, Ying W. Soon, Warren Duffy, Martin Heeney, Iain McCulloch, Jenny Nelson and James R. Durrant

      Version of Record online: 8 SEP 2010 | DOI: 10.1002/adma.201002357

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      Charge Photogeneration: The correlation between the efficiency of photogeneration of dissociated polarons and photocurrent densities for organic solar cells based on polymer:fullerene blend films is investigated. Optical assays of polaron yield measured in films without electrodes show a remarkably clear correlation with short circuit density and quantum yield measured in complete devices. For the blend films studied herein, the primary determinant of photocurrent generation is the efficiency of dissociation of photogenerated charges away from the polymer/fullerene interface and the primary loss pathway is geminate recombination.

    11. Tungsten Oxide Nanowires Grown on Carbon Cloth as a Flexible Cold Cathode (pages 5292–5296)

      Xianghui Zhang, Li Gong, Kang Liu, Yuanzhi Cao, Xu Xiao, Wanmei Sun, Xuejiao Hu, Yihua Gao, Jian Chen, Jun Zhou and Zhong Lin Wang

      Version of Record online: 13 OCT 2010 | DOI: 10.1002/adma.201002526

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      Single crystalline tungsten oxide nanowires (TONWs) have been synthesized on highly flexible, highly conductive, and highly robust carbon cloth by a catalyst-free thermal evaporation method. Field emission with a low threshold field of ∼4.30 MV m−1 was observed from the TONWs. This finding opens up opportunities to make light weight and rollable field emission displays.

    12. Real-Time DNA Detection Using Reduced Graphene Oxide Field Effect Transistors (pages 5297–5300)

      Rory Stine, Jeremy T. Robinson, Paul E. Sheehan and Cy R. Tamanaha

      Version of Record online: 24 SEP 2010 | DOI: 10.1002/adma.201002121

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      DNA sensing: Single strands of DNA are covalently attached to nanometer-thick layers of reduced graphene oxide, forming an FET device capable of sensitive, label-free detection of complementary DNA hybridization.

    13. Graded Donor-Acceptor Heterojunctions for Efficient Organic Photovoltaic Cells (pages 5301–5305)

      Richa Pandey and Russell J. Holmes

      Version of Record online: 24 SEP 2010 | DOI: 10.1002/adma.201002454

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      Graded donor-acceptor heterojunctions for efficient organic photovoltaic cells are fabricated using boron subphthalocyanine chloride (SubPc) and C60. The graded heterojunction significantly increases the exciton diffusion efficiency relative to a planar architecture, and improves the charge collection efficiency relative to a uniformly mixed architecture. A power conversion efficiency of (4.2 ± 0.1)% is realized in a graded heterojunction OPV at 100 mW cm−2 AM1.5G illumination intensity.

    14. Enhanced Self-Organized Dewetting of Ultrathin Polymer Films Under Water-Organic Solutions: Fabrication of Sub-micrometer Spherical Lens Arrays (pages 5306–5309)

      Ankur Verma and Ashutosh Sharma

      Version of Record online: 24 SEP 2010 | DOI: 10.1002/adma.201002768

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      Submicrometer spherical lenses and lens arrays are fabricated by freeing the dewetting of ultrathin (< 100 nm) polymer films from interfacial tension limitation and by harnessing the self-organization of films. The lens-size is continuously tunable from 200 nm to few tens of micrometers with contact angles ranging from 30° – 150°.

    15. Enhanced Thermal Actuation in Thin Polymer Films Through Particle Nano-Squeezing by Carbon Nanotube Belts (pages 5310–5314)

      Patnarin Worajittiphon, Izabela Jurewicz, Alice A. K. King, Joseph L. Keddie and Alan B. Dalton

      Version of Record online: 28 SEP 2010 | DOI: 10.1002/adma.201003145

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      Nanoscale belts made from carbon nanotubes encircle colloidal polymer particles arranged in an hexagonal array in a thin film. They restrict thermal expansion in the plane of the film, such that there is greater expansion in the normal direction. These nanostructure films offer potential applications in thermal actuation.

  7. Research News

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Correction
    6. Progress Report
    7. Communications
    8. Research News
    1. Switching of Ferroelectrics Without Domains (pages 5315–5317)

      James F. Scott

      Version of Record online: 25 OCT 2010 | DOI: 10.1002/adma.201003264

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      It has been known since the 1930s that ferroelectrics could theoretically reverse polarization without domain wall motion. Occasionally experimental reports claim such effects. This essay reviews the history and new evidence from Lei Zheng for this in polyvinylidene (PVDF) copolymers: two distinct critical fields and a limited temperature range (accompanying figure) for paraelectric-ferroelectric transitions induced by an applied field.

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