Advanced Materials

Cover image for Advanced Materials

January 24, 2012

Volume 24, Issue 4

Pages 445–564

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Masthead
    5. Contents
    6. Progress Report
    7. Communications
    1. Bioinspired Reversible Interlocker: Bioinspired Reversible Interlocker Using Regularly Arrayed High Aspect-Ratio Polymer Fibers (Adv. Mater. 4/2012) (page 445)

      Changhyun Pang, Tae-il Kim, Won Gyu Bae, Daeshik Kang, Sang Moon Kim and Kahp-Yang Suh

      Article first published online: 17 JAN 2012 | DOI: 10.1002/adma.201290015

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      A reversible mechanical interlocker inspired from the wing locking device of beetles is reported on page 475, by Kahp-Yang Suh and co-workers. The interlocker is highly flexible and displays an extremely high shear locking force of ∼40 N/cm2 as well as an easy normal lift-off. The image shows an illustration for the wing-locking device of beetles that is operated by interconnecting densely-populated microhairs (termed microtrichia) on the cuticular surface.

  2. Inside Front Cover

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Masthead
    5. Contents
    6. Progress Report
    7. Communications
    1. Chitosan-Fibroin Laminates: Unexpected Strength and Toughness in Chitosan-Fibroin Laminates Inspired by Insect Cuticle (Adv. Mater. 4/2012) (page 446)

      Javier G. Fernandez and Donald E. Ingber

      Article first published online: 17 JAN 2012 | DOI: 10.1002/adma.201290016

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      Javier Fernandez and Donald Ingber demonstrate on page 480 that chitosan-fibroin laminates inspired by natural insect cuticles have unexpected strength and toughness. The inside cover image shows a scaled replica of a Thesoneura Americana hind wing made of Shrilk, which is a synthetic insect cuticle material composed of a laminate of chitosan and fibroin. Thesoneura is a member of the Palepdictyoptera family that is believed to be one of the first primitive flying insects. This insect became extinct about 300 million years ago; the shape was reproduced from fossil records and the vein pattern was reproduced from a grasshopper hind wing.

  3. Masthead

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Masthead
    5. Contents
    6. Progress Report
    7. Communications
    1. Masthead: (Adv. Mater. 4/2012)

      Article first published online: 17 JAN 2012 | DOI: 10.1002/adma.201290017

  4. Contents

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Masthead
    5. Contents
    6. Progress Report
    7. Communications
    1. Contents: (Adv. Mater. 4/2012) (pages 447–452)

      Article first published online: 17 JAN 2012 | DOI: 10.1002/adma.201290014

  5. Progress Report

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Masthead
    5. Contents
    6. Progress Report
    7. Communications
    1. Layer-by-Layer Assembly Through Weak Interactions and Their Biomedical Applications (pages 454–474)

      Michiya Matsusaki, Hiroharu Ajiro, Toshiyuki Kida, Takeshi Serizawa and Mitsuru Akashi

      Article first published online: 27 DEC 2011 | DOI: 10.1002/adma.201103698

      Thumbnail image of graphical abstract

      Layer-by-layer (LbL) assemblies with molecularly regular conformation have been developed by employing weak interactions, van der Waals interactions, and biological recognition. Template polymerization, stereoregular control of biological properties, morphological control of biodegradable nano materials, and three-dimensional cellular multilayers were successfully achieved. It is expected that the LbL assembly with weak interactions promotes further interest for fundamental and applied studies in biomedical field.

  6. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Masthead
    5. Contents
    6. Progress Report
    7. Communications
    1. Bioinspired Reversible Interlocker Using Regularly Arrayed High Aspect-Ratio Polymer Fibers (pages 475–479)

      Changhyun Pang, Tae-il Kim, Won Gyu Bae, Daeshik Kang, Sang Moon Kim and Kahp-Yang Suh

      Article first published online: 23 DEC 2011 | DOI: 10.1002/adma.201103022

      Thumbnail image of graphical abstract

      A reversible interlocker that is inspired by the wing locking device of beetles is presented. It exploits the van der Waals force-assisted binding between high-aspect-ratio polymer fibers. The two-layered interlocker is highly flexible and displays an extremely high shear locking force and easy normal lift-off.

    2. Unexpected Strength and Toughness in Chitosan-Fibroin Laminates Inspired by Insect Cuticle (pages 480–484)

      Javier G. Fernandez and Donald E. Ingber

      Article first published online: 13 DEC 2011 | DOI: 10.1002/adma.201104051

      Thumbnail image of graphical abstract

      A material inspired by natural insect cuticle and composed of chitosan and fibroin is created. The material exhibits the strength of an aluminum alloy at half its weight, while being clear, biocompatible, biodegradable, and micromoldable. The bioinspired laminate exhibits strength and toughness that are ten times greater than the unstructured component blend and twice that of its strongest constituent.

    3. General and Controllable Synthesis of Novel Mesoporous Magnetic Iron Oxide@Carbon Encapsulates for Efficient Arsenic Removal (pages 485–491)

      Zhangxiong Wu, Wei Li, Paul A. Webley and Dongyuan Zhao

      Article first published online: 27 DEC 2011 | DOI: 10.1002/adma.201103789

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      A facile ammonia-atmosphere pre-hydrolysis post-synthetic route that can uniformly and selectively deposit Fe2O3 nanoparticles in the predefined mesopores (5.6 nm) of a bimodal (2.3, 5.6 nm) mesoporous carbon matrix is demonstrated (see figure). The mesoporous magnetic Fe2O3@C encapsulates show excellent performance for arsenic capture with remarkable adsorption capacity, fast uptake rate, easy magnetic separation, and good cyclic stability.

    4. Hemostatic Multilayer Coatings (pages 492–496)

      Anita Shukla, Jean C. Fang, Sravanthi Puranam, Flemming R. Jensen and Paula T. Hammond

      Article first published online: 27 DEC 2011 | DOI: 10.1002/adma.201103794

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      Spray layer-by-layer assembly is used to create hemostatic films containing thrombin and tannic acid. The spray assembly technique enables coating of porous and absorbent commercial gelatin sponges with these films. Coated sponges are able to promote instantaneous hemostasis in a porcine spleen bleeding model.

    5. Controlled Deposition of a High-Performance Small-Molecule Organic Single-Crystal Transistor Array by Direct Ink-Jet Printing (pages 497–502)

      Yong-Hoon Kim, Byungwook Yoo, John E. Anthony and Sung Kyu Park

      Article first published online: 23 DEC 2011 | DOI: 10.1002/adma.201103032

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      Ink-jet printed small-molecule organic single-crystal transistors are realized by using selective surface energy modification, precise control of volume density of ink droplets on spatially patterned areas, and a co-solvent system to control solvent evaporation properties. The single-crystal formation in bottom-contact-structured transistors via direct printing is expected to permit high-density array fabrication in large-area electronics.

    6. Band-Like Electron Transport in Organic Transistors and Implication of the Molecular Structure for Performance Optimization (pages 503–508)

      Nikolas A. Minder, Shimpei Ono, Zhihua Chen, Antonio Facchetti and Alberto F. Morpurgo

      Article first published online: 27 DEC 2011 | DOI: 10.1002/adma.201103960

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      The Hall effect and an increase of field-effect mobility with decreasing temperature is observerd in n-channel single-crystal organic field-effect transistors (OFETs). A quantitative analysis of these findings, together with results on different p-channel transistors, indicate the importance of the semiconductor molecular polarizability and the structure of the charge transport layers in the crystal for the observation of band-like transport in OFETs.

    7. Ternary Ambipolar Phosphine Oxide Hosts Based on Indirect Linkage for Highly Efficient Blue Electrophosphorescence: Towards High Triplet Energy, Low Driving Voltage and Stable Efficiencies (pages 509–514)

      Donghui Yu, Fangchao Zhao, Chunmiao Han, Hui Xu, Jing Li, Zhen Zhang, Zhaopeng Deng, Dongge Ma and Pengfei Yan

      Article first published online: 23 DEC 2011 | DOI: 10.1002/adma.201104214

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      The effective strategy of indirect linakge for constructing ternary ambipolar phosphine oxide (PO) hosts with the high first triplet energy levels (T1) was successfully demonstrated. The interplay between the chromophore, hole and electron transporting moieties was effectively restrained. Both of T1 as high as 3.0 eV and ambipolar characteristics were perfectly realized, which consequently resulted in the highly efficient blue-emitting phosphorescent organic light-emitting diodes with low driving voltage and stable efficiencies.

    8. Microstructures of GaN Thin Films Grown on Graphene Layers (pages 515–518)

      Hyobin Yoo, Kunook Chung, Yong Seok Choi, Chan Soon Kang, Kyu Hwan Oh, Miyoung Kim and Gyu-Chul Yi

      Article first published online: 27 DEC 2011 | DOI: 10.1002/adma.201103829

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      Plan-view and cross-sectional transmission electron microscopy images show the microstructural properties of GaN thin films grown on graphene layers, including dislocation types and density, crystalline orientation and grain boundaries. The roles of ZnO nanowalls and GaN intermediate layers in the heteroepitaxial growth of GaN on graphene, revealed by cross-sectional transmission electron microscopy, are also discussed.

    9. Direct Assembly of Preformed Nanoparticles and Graft Copolymer for the Fabrication of Micrometer-thick, Organized TiO2 Films: High Efficiency Solid-state Dye-sensitized Solar Cells (pages 519–522)

      Sung Hoon Ahn, Won Seok Chi, Jung Tae Park, Jong Kwan Koh, Dong Kyu Roh and Jong Hak Kim

      Article first published online: 23 DEC 2011 | DOI: 10.1002/adma.201103799

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      Solid-state dye-sensitized solar cell with 7.1% efficiency at 100 mW/cm2 is reported, one of the highest observed for N719 dye. Excellent performance was achieved via a graft copolymer-templated, organized mesoporous TiO2 film with a large surface area using spindle-shaped, preformed TiO2 nanoparticles and solid polymer electrolyte.

    10. Direct Observation of Ferrielectricity at Ferroelastic Domain Boundaries in CaTiO3 by Electron Microscopy (pages 523–527)

      Sandra Van Aert, Stuart Turner, Rémi Delville, Dominique Schryvers, Gustaaf Van Tendeloo and Ekhard K. H. Salje

      Article first published online: 23 DEC 2011 | DOI: 10.1002/adma.201103717

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      High-resolution aberration-corrected transmission electron microscopy aided by statistical parameter estimation theory is used to quantify localized displacements at a (110) twin boundary in orthorhombic CaTiO3. The displacements are 3–6 pm for the Ti atoms and confined to a thin layer. This is the first direct observation of the generation of ferroelectricity by interfaces inside this material which opens the door for domain boundary engineering.

    11. On the Existence of A-Site Deficiency in Perovskites and Its Relation to the Electrochemical Performance (pages 528–532)

      Elena Yu. Konysheva, Xiaoxiang Xu and John T. S. Irvine

      Article first published online: 23 DEC 2011 | DOI: 10.1002/adma.201103352

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      The low range of A-site deficiency in perovskite structures with Ni cations was verified by neutron powder diffraction, transmission electron microscopy, and thermogravimetric analysis. A thermodynamic approach has been utilized, for the first time, to predict the extent of A-site deficiencies within the perovskite structure, introducing simple prediction criteria that could be adopted for designing advanced materials.

    12. Towards Ultrathick Battery Electrodes: Aligned Carbon Nanotube – Enabled Architecture (pages 533–537)

      Kara Evanoff, Javed Khan, Alexander A. Balandin, Alexandre Magasinski, W. Jud Ready, Thomas F. Fuller and Gleb Yushin

      Article first published online: 27 DEC 2011 | DOI: 10.1002/adma.201103044

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      Vapor deposition techniques were utilized to synthesize very thick (∼1 mm) Li-ion battery anodes consisting of vertically aligned carbon nanotubes coated with silicon and carbon. The produced anode demonstrated ultrahigh thermal (>400 W·m−1·K−1) and high electrical (>20 S·m−1) conductivities, high cycle stability, and high average capacity (>3000 mAh·gSi−1). The processes utilized allow for the conformal deposition of other materials, thus making it a promising architecture for the development of Li-ion anodes and cathodes with greatly enhanced electrical and thermal conductivities.

    13. Highly Crystalline and Low Bandgap Donor Polymers for Efficient Polymer Solar Cells (pages 538–542)

      Jun Liu, Hyosung Choi, Jin Young Kim, Chris Bailey, Michael Durstock and Liming Dai

      Article first published online: 23 DEC 2011 | DOI: 10.1002/adma.201103623

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      A highly crystalline and low bandgap donor polymer, EI-PFDTBT, is developed by inserting ethylene bridging units to ensure a coplanar configuration between the side chains and the main chain. Polymer solar cells based on the EI-PFDTBT and PC71BM blends spincoated at elevated temperatures exhibit a power conversion efficiency of 5.1%.

    14. Hierarchical Zinc Oxide Materials with Multiple Porosity Prepared by Ultrafast Temperature Gradient Chemical Gas-Phase Synthesis (pages 543–548)

      Stefan Dilger, Carlos Lizandara-Pueyo, Michael Krumm and Sebastian Polarz

      Article first published online: 23 DEC 2011 | DOI: 10.1002/adma.201103557

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      The preparation of materials characterized by three types of porosity could be prepared by a continuous chemical gas-phase method. The multistep formation mechanism involves a critical temperature gradient and occurs within seconds. The resulting hollow aerogel materials show superior properties as gas sensors in comparison to materials constructed from compact nanoparticles.

    15. Combination of Molecular, Morphological, and Interfacial Engineering to Achieve Highly Efficient and Stable Plastic Solar Cells (pages 549–553)

      Chih-Yu Chang, Yen-Ju Cheng, Shih-Hsiu Hung, Jhong-Sian Wu, Wei-Shun Kao, Chia-Hao Lee and Chain-Shu Hsu

      Article first published online: 23 DEC 2011 | DOI: 10.1002/adma.201103945

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      A flexible solar device showing exceptional air and mechanical stability is produced by simultaneously optimizing molecular structure, active layer morphology, and interface characteristics. The PFDCTBT-C8-based (see figure) devices with inverted architecture exhibited excellent power conversion efficiencies of 7.0% and 6.0% on glass and flexible substrates, respectively.

    16. Interlayer for Modified Cathode in Highly Efficient Inverted ITO-Free Organic Solar Cells (pages 554–558)

      Zheng Tang, L. Mattias Andersson, Zandra George, Koen Vandewal, Kristofer Tvingstedt, Patrik Heriksson, Renee Kroon, Mats R. Andersson and Olle Inganäs

      Article first published online: 17 JAN 2012 | DOI: 10.1002/adma.201104579

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      Inverted polymer solar cells with a bottom metal cathode modified by a conjugated polymer interlayer show considerable improvement of photocurrent and fill factor, which is due to hole blocking at the interlayer, and a modified surface energy which affects the nanostructure in the TQ1/[70]PCBM blend.

    17. Elaborate Positioning of Nanowire Arrays Contributed by Highly Adhesive Superhydrophobic Pillar-Structured Substrates (pages 559–564)

      Bin Su, Shutao Wang, Jie Ma, Yuchen Wu, Xiao Chen, Yanlin Song and Lei Jiang

      Article first published online: 23 DEC 2011 | DOI: 10.1002/adma.201104019

      Thumbnail image of graphical abstract

      Elaborate positioning of nanowire arrays can be generated upon highly adhesive superhydrophobic pillar-structured silicon substrates. The site of each nanowire can be precisely positioned by well designed tip-structured micropillars, yielding on-demand nanowire patterns. This approach might affect existing applications and enable new opportunities in organically functional devices and bio/chemical sensors.

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