Advanced Materials

Cover image for Vol. 25 Issue 46

December 10, 2013

Volume 25, Issue 46

Pages 6635–6770

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Masthead
    6. Contents
    7. Reviews
    8. Frontispiece
    9. Communications
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      Nanoparticle Helices: Highly Stretchable Nanoparticle Helices Through Geometric Asymmetry and Surface Forces (Adv. Mater. 46/2013) (page 6635)

      Jonathan T. Pham, Jimmy Lawrence, Dong Yun Lee, Gregory M. Grason, Todd Emrick and Alfred J. Crosby

      Version of Record online: 9 DEC 2013 | DOI: 10.1002/adma.201370287

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      A universal mechanism for helical ribbon formation through nanoscale geometric asymmetry and surface forces is described by Alfred J. Crosby, Todd Emrick, Gregory M. Grason and co-workers on page 6703. It allows for the creation of helices from a range of organic and inorganic materials, such as fluorescent quantum dot nanoparticles (NPs). These NP helices are mechanically robust, highly stretchable, and display spring-like characteristics, offering promise towards the creation of three-dimensional, stretchable NP-based devices.

  2. Inside Front Cover

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Masthead
    6. Contents
    7. Reviews
    8. Frontispiece
    9. Communications
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      Mechanical Resonators: Single-Layer MoS2 Mechanical Resonators (Adv. Mater. 46/2013) (page 6636)

      Andres Castellanos-Gomez, Ronald van Leeuwen, Michele Buscema, Herre S. J. van der Zant, Gary A. Steele and Warner J. Venstra

      Version of Record online: 9 DEC 2013 | DOI: 10.1002/adma.201370288

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      Single-layer molybdenum disulfide (MoS2) mechanical resonators are fabricated by Andres Castellanos-Gomez and co-workers on page 6719. The dynamics of these atomically thin resonators are studied by optical interferometry: they behave as membranes with resonance frequencies in the range of 10 to 30 MHz and quality factors up to 109. Clear signatures of non-linear resonance in these atomically thin resonators are also shown. Due to the combination of excellent mechanical properties with an intrinsic large direct bandgap, single-layer MoS2 mechanical resonators have a great potential for application as nano-electromechanical systems.

  3. Back Cover

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Masthead
    6. Contents
    7. Reviews
    8. Frontispiece
    9. Communications
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      Light-Emitting Devices: High-Efficiency Polymer Light-Emitting Devices with Robust Phosphorescent Platinum(II) Emitters Containing Tetradentate Dianionic ONCN Ligands (Adv. Mater. 46/2013) (page 6774)

      Gang Cheng, Pui-Keong Chow, Steven C. F. Kui, Chi-Chung Kwok and Chi-Ming Che

      Version of Record online: 9 DEC 2013 | DOI: 10.1002/adma.201370289

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      [Pt(O∧N∧C∧N)]-type complexes are used as single emitters in solution-processed polymer light-emitting diodes (PLEDs), with a maximum external quantum efficiency (EQE) of 15.55% for green and 12.73% for white devices, respectively. These values, determined by Chi-Ming Che and co-workers, as described on page 6765, are the highest values ever achieved for PLEDs based on Pt(II) complexes and white PLEDs based on single emitters.

  4. Masthead

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    5. Masthead
    6. Contents
    7. Reviews
    8. Frontispiece
    9. Communications
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      Masthead: (Adv. Mater. 46/2013)

      Version of Record online: 9 DEC 2013 | DOI: 10.1002/adma.201370290

  5. Contents

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Masthead
    6. Contents
    7. Reviews
    8. Frontispiece
    9. Communications
    1. You have free access to this content
  6. Reviews

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    5. Masthead
    6. Contents
    7. Reviews
    8. Frontispiece
    9. Communications
    1. 25th Anniversary Article: A Decade of Organic/Polymeric Photovoltaic Research (pages 6642–6671)

      Letian Dou, Jingbi You, Ziruo Hong, Zheng Xu, Gang Li, Robert A. Street and Yang Yang

      Version of Record online: 18 SEP 2013 | DOI: 10.1002/adma.201302563

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      In this review article, we take a retrospective look at the research and development in organic photovoltaics (OPVs), and focus on recent advances of solution-processed materials and devices during the last decade, in particular the polymer version of the materials and devices. The work in this field is exciting and OPV technology is a promising candidate for future thin film solar cells.

    2. Melt Infiltration: an Emerging Technique for the Preparation of Novel Functional Nanostructured Materials (pages 6672–6690)

      Petra E. de Jongh and Tamara M. Eggenhuisen

      Version of Record online: 8 SEP 2013 | DOI: 10.1002/adma.201301912

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      Melt infiltration has in recent years emerged as a preparation strategy for a wide range of advanced nanostructured materials, including metals, polymers, ceramics, and metal hydrides and oxides. In specific cases, it offers extended control over the nanostructure and the assembly of novel nanocomposites, facilitating the exploration of new functionalities and fundamental size and confinement effects.

  7. Frontispiece

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Masthead
    6. Contents
    7. Reviews
    8. Frontispiece
    9. Communications
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      Pressure Sensors: A Flexible and Highly Pressure-Sensitive Graphene–Polyurethane Sponge Based on Fractured Microstructure Design (Adv. Mater. 46/2013) (page 6691)

      Hong-Bin Yao, Jin Ge, Chang-Feng Wang, Xu Wang, Wei Hu, Zhi-Jun Zheng, Yong Ni and Shu-Hong Yu

      Version of Record online: 9 DEC 2013 | DOI: 10.1002/adma.201370292

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      A new type of piezoresistive sensor with ultrahigh pressure sensitivity in the low-pressure range and minimum detectable pressure of 9 Pa is fabricated based on a fractured microstructure design in a graphene-nanosheet-wrapped polyurethane sponge (PUS), as described by Shu-Hong Yu and co-workers on Page 6692. This low-cost and facilely scalable graphene-wrapped PUS pressure sensor has potential applications in high-spatial-resolution artificial skin without a complex nanostructure design.

  8. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Masthead
    6. Contents
    7. Reviews
    8. Frontispiece
    9. Communications
    1. A Flexible and Highly Pressure-Sensitive Graphene–Polyurethane Sponge Based on Fractured Microstructure Design (pages 6692–6698)

      Hong-Bin Yao, Jin Ge, Chang-Feng Wang, Xu Wang, Wei Hu, Zhi-Jun Zheng, Yong Ni and Shu-Hong Yu

      Version of Record online: 12 SEP 2013 | DOI: 10.1002/adma.201303041

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      A fractured microstructure design: A new type of piezoresistive sensor with ultra-high-pressure sensitivity (0.26 kPa−1) in low pressure range (<2 kPa) and minimum detectable pressure of 9 Pa has been fabricated using a fractured microstructure design in a graphene-nanosheet-wrapped polyurethane (PU) sponge. This low-cost and easily scalable graphene-wrapped PU sponge pressure sensor has potential application in high-spatial-resolution, artificial skin without complex nanostructure design.

    2. High-Performance Sensors Based on Molybdenum Disulfide Thin Films (pages 6699–6702)

      Kangho Lee, Riley Gatensby, Niall McEvoy, Toby Hallam and Georg S. Duesberg

      Version of Record online: 12 SEP 2013 | DOI: 10.1002/adma.201303230

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      High-performance sensors based on molybdenum disulfide (MoS2) grown by sulfurization of sputtered molybdenum layers are presented. Using a simple integration scheme, it is found that the electrical conductivity of MoS2 films is highly sensitive to NH3 adsorption, consistent with n-type semiconducting behavior. A sensitivity of 300 ppb at room temperature is achieved, showing the high potential of 2D transition metal-dichalcogenides for sensing.

    3. Highly Stretchable Nanoparticle Helices Through Geometric Asymmetry and Surface Forces (pages 6703–6708)

      Jonathan T. Pham, Jimmy Lawrence, Dong Yun Lee, Gregory M. Grason, Todd Emrick and Alfred J. Crosby

      Version of Record online: 16 SEP 2013 | DOI: 10.1002/adma.201302817

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      Geometric asymmetry and surface forces are used directly the shape transformation of two-dimensional nanoparticle (NP)-based ribbons into three-dimensional helices. The balance between elasticity and surface tension dictates the helical radius dimension. NP helical ribbons have exceptional mechanical properties, displaying high stretchability, helical shape recovery after extension, and low-strain stiffness values similar to biological helices.

    4. Soft Machines That are Resistant to Puncture and That Self Seal (pages 6709–6713)

      Robert F. Shepherd, Adam A. Stokes, Rui M. D. Nunes and George M. Whitesides

      Version of Record online: 7 OCT 2013 | DOI: 10.1002/adma.201303175

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      A soft machine composed of a composite of elastomer and fibers resists puncture from sharp objects, and continues to operate even if punctured.

    5. Controlled Inkjetting of a Conductive Pattern of Silver Nanoparticles Based on the Coffee-Ring Effect (pages 6714–6718)

      Zhiliang Zhang, Xingye Zhang, Zhiqing Xin, Mengmeng Deng, Yongqiang Wen and Yanlin Song

      Version of Record online: 7 OCT 2013 | DOI: 10.1002/adma.201303278

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      Conductive patterns with line widths of 5–10 µm are successfully fabricated by utilizing the coffee-ring effect in inkjet printing, resulting in transmittance values of up to 91.2% in the visible to near-infrared region. This non-lithographic approach broadens the range of fabrication procedures that can be used to create various nanoparticle-based microstructures and electronic devices.

    6. Single-Layer MoS2 Mechanical Resonators (pages 6719–6723)

      Andres Castellanos-Gomez, Ronald van Leeuwen, Michele Buscema, Herre S. J. van der Zant, Gary A. Steele and Warner J. Venstra

      Version of Record online: 2 OCT 2013 | DOI: 10.1002/adma.201303569

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      Mechanical resonators are fabricated from freely suspended single-layer MoS2. Their dynamics  have been studied by optical interferometry. These resonators behave as membranes with resonance frequencies in between 10 and 30 MHz and quality factors in between 16 and 109. We also demonstrate clear signatures of nonlinear resonance in these atomically thin resonators.

    7. Enhanced Mechanical Properties of Graphene/Copper Nanocomposites Using a Molecular-Level Mixing Process (pages 6724–6729)

      Jaewon Hwang, Taeshik Yoon, Sung Hwan Jin, Jinsup Lee, Taek-Soo Kim, Soon Hyung Hong and Seokwoo Jeon

      Version of Record online: 25 AUG 2013 | DOI: 10.1002/adma.201302495

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      RGO flakes are homogeneously dispersed in a Cu matrix through a molecular-level mixing process. This novel fabrication process prevents the agglomeration of the RGO and enhances adhesion between the RGO and the Cu. The yield strength of the 2.5 vol% RGO/Cu nanocomposite is 1.8 times higher than that of pure Cu. The strengthening mechanism of the RGO is investigated by a double cantilever beam test using the graphene/Cu model structure.

    8. Synergistic Co-Delivery of Membrane-Disrupting Polymers with Commercial Antibiotics against Highly Opportunistic Bacteria (pages 6730–6736)

      Victor Wee Lin Ng, Xiyu Ke, Ashlynn L. Z. Lee, James L. Hedrick and Yi Yan Yang

      Version of Record online: 9 SEP 2013 | DOI: 10.1002/adma.201302952

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      A series of vitamin E-containing biodegradable antimicrobial cationic polycarbonates is designed and synthesized via controlled organocatalytic ring-opening polymerization. The incorporation of vitamin E significantly enhances antimicrobial activity. These polymers demonstrate broad-spectrum antimicrobial activity against various microbes, e.g., S. aureus (Gram-positive), E-coli (Gram-negative) and C. albicans (fungi). More importantly, the co-delivery of such polymers with selected antibiotics (e.g., doxycycline) shows high synergism towards difficult-to-kill bacteria P. aeruginosa. These findings suggest that these vitamin E-functionalized polycarbonates are potentially useful antimicrobial agents against challenging bacterial/fungal infections.

    9. 3D Graphene Oxide–Polymer Hydrogel: Near-Infrared Light-Triggered Active Scaffold for Reversible Cell Capture and On-Demand Release (pages 6737–6743)

      Wen Li, Jiasi Wang, Jinsong Ren and Xiaogang Qu

      Version of Record online: 7 OCT 2013 | DOI: 10.1002/adma.201302810

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      An active cell scaffold based on a graphene–polymer hydrogel has been successfully fabricated. The macroporous hydrogel can efficiently capture cells not only through the bioadhesive ligand RGD but also through on-demand release of cells with an NIR light stimulus. The latter process shows better dynamic control over cells than traditional passive-hydrogel-based cell depots.

    10. Crystal Structure Evolution of Individual Graphene Islands During CVD Growth on Copper Foil (pages 6744–6751)

      Yaping Wu, Yufeng Hao, Hu Young Jeong, Zonghoon Lee, Shanshan Chen, Wei Jiang, Qingzhi Wu, Richard D. Piner, Junyong Kang and Rodney S. Ruoff

      Version of Record online: 10 SEP 2013 | DOI: 10.1002/adma.201302208

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      Single-crystal percentage of graphene islands on Cu foil is associated with island sizes and shapes. In polycrystalline islands, certain grain boundary types are favored. There is no obvious relation between the number of lobes and grain orientations. An observed structure evolution and surface disorder of Cu grains can be possible factors for the formation of grain boundaries within graphene islands.

    11. Interface-Engineered Bistable [2]Rotaxane-Graphene Hybrids with Logic Capabilities (pages 6752–6759)

      Chuancheng Jia, Hao Li, Jiaolong Jiang, Jindong Wang, Hongliang Chen, Dennis Cao, J. Fraser Stoddart and Xuefeng Guo

      Version of Record online: 9 SEP 2013 | DOI: 10.1002/adma.201302393

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      The use of high-quality graphene as a local probe in combination with photo excitation helps to establish a deep mechanistic understanding of charge generation/quenching processes under lying the graphene/environment interface. By combining a non-destructive bottom-up assembly technique with sensitive graphene-based transistors, a bistable [2]rotaxane-graphene hybrid device, which exhibits a symmetric mirror-image photoswitching effect with logic capabilities, is produced.

    12. A Direct Evidence of Morphological Degradation on a Nanometer Scale in Polymer Solar Cells (pages 6760–6764)

      Christoph J. Schaffer, Claudia M. Palumbiny, Martin A. Niedermeier, Christian Jendrzejewski, Gonzalo Santoro, Stephan V. Roth and Peter Müller-Buschbaum

      Version of Record online: 12 SEP 2013 | DOI: 10.1002/adma.201302854

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      In situ measurement of a polymer solar cell using micro grazing incidence small angle X-ray scattering (μGISAXS) and current–voltage tracking is demonstrated. While measuring electric characteristics under illumination, morphological changes are probed by μGISAXS. The X-ray beam (green) impinges on the photo active layer with a shallow angle and scatters on a 2d detector. Degradation is explained by the ongoing nanomorphological changes observed.

    13. High-Efficiency Polymer Light-Emitting Devices with Robust Phosphorescent Platinum(II) Emitters Containing Tetradentate Dianionic ONCN Ligands (pages 6765–6770)

      Gang Cheng, Pui-Keong Chow, Steven C. F. Kui, Chi-Chung Kwok and Chi-Ming Che

      Version of Record online: 12 AUG 2013 | DOI: 10.1002/adma.201302408

      Thumbnail image of graphical abstract

      [Pt(ONCN)]-type complexes are used as single emitters in solution-processed PLEDs with maximum EQEs of 15.55% for green and 12.73% for white devices, which are the highest values ever achieved for PLEDs based on Pt(ii) complexes.

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