Advanced Materials

Cover image for Vol. 21 Issue 44

November 26, 2009

Volume 21, Issue 44

Pages 4413–4510

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Progress Report
    6. Communications
    1. Shrink-Induced Nanowrinkles: Tunable Nanowrinkles on Shape Memory Polymer Sheets (Adv. Mater. 44/2009)

      Chi-Cheng Fu, Anthony Grimes, Maureen Long, Christopher G. L. Ferri, Brent D. Rich, Somnath Ghosh, Sayantani Ghosh, Luke P. Lee, Ajay Gopinathan and Michelle Khine

      Version of Record online: 24 NOV 2009 | DOI: 10.1002/adma.200990163

      Thumbnail image of graphical abstract

      By leveraging the mismatch in stiffness between a stiff thin metal film and heat-induced shrinkage of prestressed polystyrene sheets, Michelle Khine and co-workers can rapidly and controllably create tunable nanowrinkles of various sizes and shapes for surface-enhanced sensing applications, as reported on p. 4472. Because the wrinkles are robustly embedded into the plastic, nanostructures can be integrated into microfluidic channels within minutes. Cover design by Libre Design.

  2. Inside Front Cover

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Progress Report
    6. Communications
    1. Carbon Nanotube Junctions: Multibranched Junctions of Carbon Nanotubes via Cobalt Particles (Adv. Mater. 44/2009)

      Julio A. Rodríguez-Manzo, Ming-Sheng Wang, Florian Banhart, Yoshio Bando and Dmitri Golberg

      Version of Record online: 24 NOV 2009 | DOI: 10.1002/adma.200990164

      Thumbnail image of graphical abstract

      Junctions between different carbon nanotubes (CNTs) created using cobalt particles as central nodes (background) are demonstrated by Ming-Sheng Wang and co-workers on p. 4477. The process involves high-temperature electron irradiation of areas where a metal particle is located at the overlapping region of two CNTs. In situ transmission electron microscopy measurements show that the junctions are electrically conductive and mechanically robust. The extension of this technique towards creating more complicated structures, such as a 3D CNT network, is also depicted in the cover.

  3. Contents

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Progress Report
    6. Communications
  4. Progress Report

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Progress Report
    6. Communications
    1. Recent Developments in the Application of Phosphorescent Iridium(III) Complex Systems (pages 4418–4441)

      Christoph Ulbricht, Beatrice Beyer, Christian Friebe, Andreas Winter and Ulrich S. Schubert

      Version of Record online: 1 OCT 2009 | DOI: 10.1002/adma.200803537

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      Phosphorescent iridium(III) complexes as emissive species in various recent applications are reviewed. The developments in the synthesis and application of these Ir(III) complexes are discussed. Here, special attention is drawn to polymer-containing materials. Ir(III) emitters are highlighted as key materials in the areas of OLEDs, light-emitting electrochemical cells, sensors, water-splitting technology, and biolabeling.

  5. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Progress Report
    6. Communications
    1. Translating Electronic Currents to Precise Acetylcholine–Induced Neuronal Signaling Using an Organic Electrophoretic Delivery Device (pages 4442–4446)

      Klas Tybrandt, Karin C. Larsson, Sindhulakshmi Kurup, Daniel T. Simon, Peter Kjäll, Joakim Isaksson, Mats Sandberg, Edwin W. H. Jager, Agneta Richter-Dahlfors and Magnus Berggren

      Version of Record online: 6 JUL 2009 | DOI: 10.1002/adma.200900187

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      A miniaturized organic electronic ion pump (OEIP) based on conjugated polymers is developed for delivery of positively charged biomolecules. Characterization shows that applied voltage can precisely modulate the delivery rate of the neurotransmitter acetylcholine. The capability of the device is demonstrated by convection-free, spatiotemporally resolved delivery of acetylcholine via a 10 µm channel for dynamic stimulation of single neuronal cells.

    2. Efficient, Stable Bulk Charge Transport in Crystalline/Crystalline Semiconductor–Insulator Blends (pages 4447–4451)

      Avinesh Kumar, Mohammed A. Baklar, Ken Scott, Theo Kreouzis and Natalie Stingelin-Stutzmann

      Version of Record online: 1 JUL 2009 | DOI: 10.1002/adma.200900717

      Thumbnail image of graphical abstract

      Efficient and stable ambipolar charge transport in the bulk of crystalline/crystalline P3HT/HDPE systems, as evidenced by time-of-flight (TOF) photoconductivity measurements, is found. Interestingly, certain blend compositions displayed significantly enhanced bulk charge-transport properties compared to neat P3HT, with μTOF measured for 80:20 wt% P3HT:PE blends being up to one order of magnitude higher than those found in neat P3HT.

    3. Ferroelectric Switching in Multiferroic Magnetite (Fe3O4) Thin Films (pages 4452–4455)

      Marin Alexe, Michael Ziese, Dietrich Hesse, Pablo Esquinazi, Kunihiko Yamauchi, Tetsuya Fukushima, Silvia Picozzi and Ulrich Gösele

      Version of Record online: 6 JUL 2009 | DOI: 10.1002/adma.200901381

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      Real-time ferroelectric polarization switching in magnetite epitaxial thin films is reported, proving that magnetite is not only historically the first material showing magnetism and correlated electron properties, but also that it is ferroelectric with a value of the ferroelectric polarization approaching that of well-known ferroelectric materials such as BaTiO3.

    4. Ground-State Interaction and Electrical Doping of Fluorinated C60 in Conjugated Polymers (pages 4456–4460)

      Olga Solomeshch, Young Jun Yu, Alexey A. Goryunkov, Lev N. Sidorov, Renat F. Tuktarov, Dong Hoon Choi, Jung-Il Jin and Nir Tessler

      Version of Record online: 1 JUL 2009 | DOI: 10.1002/adma.200900798

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      C60F36 is reported to be an efficient dopant for conjugated polymers. Its fluorine atoms induce a large shift in the energy levels with respect to C60. Its role as a dopant is studied by examining the charge transfer formed with the commonly used polymer, P3HT.

    5. Improved Photovoltaic Performance of Heterostructured Tetrapod-Shaped CdSe/CdTe Nanocrystals Using C60 Interlayer (pages 4461–4466)

      Yanqin Li, Rosanna Mastria, Angela Fiore, Concetta Nobile, Lunxiang Yin, Mariano Biasiucci, Gang Cheng, Anna Maria Cucolo, Roberto Cingolani, Liberato Manna and Giuseppe Gigli

      Version of Record online: 24 JUN 2009 | DOI: 10.1002/adma.200901338

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      Photovoltaic (PV) devices based on CdSe/CdTe-C60 active layers, in which the nanocrystal and fullerene (C60) layers work as electron-donor and electron-acceptor/transport layers, respectively, were fabricated. Efficiencies up to 0.62% were reached in the hybrid cells. The PV performance was greatly improved with respect to that of CdSe/CdTe-P3HT- and CdSe/CdTe-based devices, fabricated as reference.

    6. Nonblinking and Nonbleaching Upconverting Nanoparticles as an Optical Imaging Nanoprobe and T1 Magnetic Resonance Imaging Contrast Agent (pages 4467–4471)

      Yong Il Park, Jeong Hyun Kim, Kang Taek Lee, Ki-Seok Jeon, Hyon Bin Na, Jung Ho Yu, Hyung Min Kim, Nohyun Lee, Seung Hong Choi, Sung-Il Baik, Hyoungsu Kim, Seung Pyo Park, Beom-Jin Park, Young Woon Kim, Sung Ho Lee, Soo-Young Yoon, In Chan Song, Woo Kyung Moon, Yung Doug Suh and Taeghwan Hyeon

      Version of Record online: 29 JUN 2009 | DOI: 10.1002/adma.200901356

      Thumbnail image of graphical abstract

      Core/shell upconverting nanoparticles (UCNPs) of NaGdF4:Er3+,Yb3+/NaGdF4 (see figure) are shown to serve as a multimodal imaging probe that works for both background-free optical imaging and magnetic resonance imaging (MRI). The nonblinking and nonbleaching properties of UCNPs can contribute to minimization of possible artifacts in long-term imaging experiments. Owing to Gd3+ ions in the host matrix, contrast is enhanced in T1-weighted MRI.

    7. Tunable Nanowrinkles on Shape Memory Polymer Sheets (pages 4472–4476)

      Chi-Cheng Fu, Anthony Grimes, Maureen Long, Christopher G. L. Ferri, Brent D. Rich, Somnath Ghosh, Sayantani Ghosh, Luke P. Lee, Ajay Gopinathan and Michelle Khine

      Version of Record online: 20 AUG 2009 | DOI: 10.1002/adma.200902294

      Thumbnail image of graphical abstract

      Controllable biaxial and uniaxial nanowrinkles (see figure) are fabricated by a simple two-step approach — metal deposition and subsequent heating — based on shape memory polymer (prestressed polystyrene) sheets. The wavelengths of the wrinkles can be tuned by controlling the thickness of deposited metal. The ready integration of the nanowrinkles into microchannels and their effectiveness in surface enhanced sensing is demonstrated.

    8. Multibranched Junctions of Carbon Nanotubes via Cobalt Particles (pages 4477–4482)

      Julio A. Rodríguez-Manzo, Ming-Sheng Wang, Florian Banhart, Yoshio Bando and Dmitri Golberg

      Version of Record online: 24 SEP 2009 | DOI: 10.1002/adma.200901321

      Thumbnail image of graphical abstract

      Junctions between different carbon nanotubes are created using cobalt particles as central nodes (see image). The process involves high temperature and electron irradiation of areas where a metal particle is located at the overlapping region of two nanotubes. In situ transmission electron microscopy measurements show that the junctions are electrically conductive and mechanically robust. A high breaking strength of 1–5 GPa is found for the junctions.

    9. Spatially Selective Functionalization of Conducting Polymers by “Electroclick” Chemistry (pages 4483–4486)

      Thomas Steen Hansen, Anders Egede Daugaard, Søren Hvilsted and Niels B. Larsen

      Version of Record online: 13 JUL 2009 | DOI: 10.1002/adma.200900980

      Thumbnail image of graphical abstract

      Conducting polymer microelectrodes can electrochemically generate the catalyst required for their own functionalization by “click chemistry” with high spatial resolution. Interdigitated microelectrodes prepared from an azide-containing conducting polymer are selectively functionalized in sequence by two alkyne-modified fluorophores by control of the applied potentials.

    10. Graphene Shape Control by Multistage Cutting and Transfer (pages 4487–4491)

      Lijie Ci, Li Song, Deep Jariwala, Ana Laura Elías, Wei Gao, Mauricio Terrones and Pulickel M. Ajayan

      Version of Record online: 1 JUL 2009 | DOI: 10.1002/adma.200900942

      Thumbnail image of graphical abstract

      Cutting graphene by a catalytic hydrogenation process can generate graphene pieces with smooth edges of atomic precision and well-defined shapes. Controlled cutting of graphene by creating graphene step edges by oxidation or plasma etching is demonstrated. A combination of cutting, transfer, and lithography is shown to allow the fabrication of isolated graphene devices with specific edge and shape control.

    11. Micrometer-Sized Organic Single Crystals, Anisotropic Transport, and Field-Effect Transistors of a Fused-Ring Thienoacene (pages 4492–4495)

      Rongjin Li, Lang Jiang, Qing Meng, Jianhua Gao, Hongxiang Li, Qingxin Tang, Meng He, Wenping Hu, Yunqi Liu and Daoben Zhu

      Version of Record online: 2 JUL 2009 | DOI: 10.1002/adma.200900934

      Thumbnail image of graphical abstract

      Hexagonal micrometer-sized organic single crystals of a fused-ring thienoacene are grown controllably by physical vapor transport over a large area. A “two-dimensional organic-ribbon mask” technique is developed to fabricate organic field-effect transistors based on an individual microcrystal. The accomplished transistors exhibit mobility as high as 1.8 cm2V−1s−1 with on/off ratios of typically >107.

    12. Modification of the Surface Properties of Indium Tin Oxide with Benzylphosphonic Acids: A Joint Experimental and Theoretical Study (pages 4496–4501)

      Peter J. Hotchkiss, Hong Li, Pavel B. Paramonov, Sergio A. Paniagua, Simon C. Jones, Neal R. Armstrong, Jean-Luc Brédas and Seth R. Marder

      Version of Record online: 6 JUL 2009 | DOI: 10.1002/adma.200900502

      Thumbnail image of graphical abstract

      Benzylphosphonic acids with various fluorine substitutions are designed and synthesized. They are used to modify ITO such that the work function can be tuned over a range of 1.2 eV while keeping the surface energy relatively constant. The experimentally measured work function changes are also compared to and agree well with those estimated from DFT calculations.

    13. Ultrarapid Microwave Synthesis of Superconducting Refractory Carbides (pages 4502–4504)

      Simon R. Vallance, David M. Round, Clemens Ritter, Edmund. J. Cussen, Sam Kingman and Duncan H. Gregory

      Version of Record online: 1 JUL 2009 | DOI: 10.1002/adma.200900968

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      Nb1−xTaxC Carbides can be synthesized by high power MW methods in less than 30 s. In situ and ex situ techniques probing changes in temperature and dielectric properties with time demonstrate that the reactions self-terminate as the loss tangent of the materials decreases. The resulting carbides are carbon deficient and superconducting; Tc correlates linearly to unit cell volume, reaching a maximum at NbC.

    14. Vertical Transistor with Ultrathin Silicon Nitride Gate Dielectric (pages 4505–4510)

      Maryam Moradi, Arokia Nathan, Hanna M. Haverinen and Ghassan E. Jabbour

      Version of Record online: 27 JUL 2009 | DOI: 10.1002/adma.200900757

      Thumbnail image of graphical abstract

      Nanoscale vertical thin-film transistors (VTFTs) are fabricated employing a new ultrathin silicon nitride (SiNx) gate dielectric for applications in high-resolution active matrix flat panel electronics. Illustrated are the cross-section schematic and SEM image of a 500 nm channel length VTFT with a 50 nm thick SiNx gate dielectric. The device demonstrates excellent gate control with gate leakage as low as 0.1 nA cm−2.

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