Advanced Materials

Cover image for Vol. 22 Issue 22

June 11, 2010

Volume 22, Issue 22

Pages 2387–2471

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Contents
    4. Review
    5. Communications
    1. Photosensitive Nanocomposites: Highly Non-Linear Quantum Dot Doped Nanocomposites for Functional Three-Dimensional Structures Generated by Two-Photon Polymerization (Adv. Mater. 22/2010)

      Baohua Jia, Dario Buso, Joel van Embden, Jiafang Li and Min Gu

      Article first published online: 2 JUN 2010 | DOI: 10.1002/adma.201090078

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      Baohua Jia, Min Gu, and co-workers report on p. 2463 on novel quantum dot functionalized photosensitive nanocomposites showing ultrahigh third-order nonlinearity. The cover image shows functional three-dimensional micronano photonic structures, for example, photonic crystals can be fabricated in such active nanocomposites using the versatile two-photon poly-merisation method, opening various possibilities in active micro/nano devices, such as ultrafast switching, signal regeneration, and high speed demultiplexing systems.

  2. Contents

    1. Top of page
    2. Cover Picture
    3. Contents
    4. Review
    5. Communications
    1. Contents: (Adv. Mater. 22/2010) (pages 2387–2391)

      Article first published online: 2 JUN 2010 | DOI: 10.1002/adma.201090079

  3. Review

    1. Top of page
    2. Cover Picture
    3. Contents
    4. Review
    5. Communications
    1. Chemically Derived Graphene Oxide: Towards Large-Area Thin-Film Electronics and Optoelectronics (pages 2392–2415)

      Goki Eda and Manish Chhowalla

      Article first published online: 28 APR 2010 | DOI: 10.1002/adma.200903689

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      For over 150 years, oxidation of graphite has been known to result in water-soluble graphite oxide. However, it has been only recently recognized that graphite oxide splits into atomically thin graphene oxide (GO) upon dissolution. GO can be produced on a large scale, handled in solution, assembled into thin films, and deposited on arbitrary substrates. This Review introduces fundamental properties of GO and summarizes recent achievements in device applications.

  4. Communications

    1. Top of page
    2. Cover Picture
    3. Contents
    4. Review
    5. Communications
    1. Optically Selective Microlens Photomasks Using Self-Assembled Smectic Liquid Crystal Defect Arrays (pages 2416–2420)

      Yun Ho Kim, Jeong-Oen Lee, Hyeon Su Jeong, Jung Hyun Kim, Eun Kyung Yoon, Dong Ki Yoon, Jun-Bo Yoon and Hee-Tae Jung

      Article first published online: 7 APR 2010 | DOI: 10.1002/adma.200903728

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      A photomask that combines two imaging elements (microlens arrays and clear windows) in one structure has been developed by using toric focal conic domain (TFCD) micro arrays of smectic liquid crystals. Their application as optically selective photomasks by simply adjusting (i) the illumination dose, (ii) the size of TFCD array mask, and (iii) the tone of photoresist (PR) is demonstrated (see figure).

    2. Fabrication of Surface Plasmon-Coupled Si Nanodots in Au-Embedded Silicon Oxide Nanowires (pages 2421–2425)

      Gyeong-Su Park, Hyuksang Kwon, Eun Kyung Lee, Seong Keun Kim, Jun Ho Lee, Xiang Shu Li, Jae Gwan Chung, Sung Heo, In Yong Song, Jae Hak Lee, Byoung Lyong Choi and Jong Min Kim

      Article first published online: 15 APR 2010 | DOI: 10.1002/adma.201000328

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      High-density amorphous silicon nanodots are easily produced by irradiating gold-nanoparticle-embedded silicon oxide nanowires with a low-intensity electron beam. The optical characteristics of Si nanodots in the vicinity of gold nanoparticles exhibit evidence of strong coupling to the surface plasmon resonance of the Au nanoparticles, as manifested by their markedly enhanced electron-induced excitation in our monochromated scanning transmission electron microscopy–electron energy-loss spectroscopy measurements.

    3. Solvent-Assisted Decal Transfer Lithography by Oxygen-Plasma Bonding and Anisotropic Swelling (pages 2426–2429)

      Pilnam Kim, Rhokyun Kwak, Sung Hoon Lee and Kahp Y. Suh

      Article first published online: 29 APR 2010 | DOI: 10.1002/adma.200903440

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      Solvent-assisted decal transfer lithography (DTL) enables the formation of well-defined micro-/nanostructures over a large area (∼4 in. wafer) by combining irreversible oxygen bonding and anisotropic swelling of poly(dimethoxylsiloxane) (PDMS). Such swelling-induced stress gradient allows for cohesion failure of the skin layer upon removal of the stamp, leaving behind a highly uniform layer (∼100 nm).

    4. Direct Evidence for Cation Non-Stoichiometry and Cottrell Atmospheres Around Dislocation Cores in Functional Oxide Interfaces (pages 2430–2434)

      Miryam Arredondo, Quentin M. Ramasse, Matthew Weyland, Reza Mahjoub, Ionela Vrejoiu, Dietrich Hesse, Nigel D. Browning, Marin Alexe, Paul Munroe and Valanoor Nagarajan

      Article first published online: 29 APR 2010 | DOI: 10.1002/adma.200903631

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      Long-range strain fields associated with dislocation cores at an oxide interface are shown to be sufficient enough to create significant variations in the chemical composition around the core (Cottrell atmospheres). Such stress-assisted diffusion of cations towards the cores is proposed to significantly impact the properties of nanoscale functional devices. The figure shows a Z-contrast image of a single dislocation core at an oxide interface.

    5. Multilayered Core/Shell Nanowires Displaying Two Distinct Magnetic Switching Events (pages 2435–2439)

      Yuen Tung Chong, Detlef Görlitz, Stephan Martens, Man Yan Eric Yau, Sebastian Allende, Julien Bachmann and Kornelius Nielsch

      Article first published online: 28 APR 2010 | DOI: 10.1002/adma.200904321

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      Atomic layer deposition (ALD) and electrodeposition are combined with a porous template to create ordered arrays of nanowires in which a nickel core and an iron oxide shell are separated by a silica spacer layer. The switching of each magnetic component is distinct and occurs at a field that depends on the tunable thicknesses of the various layers.

    6. A pH-Gating Ionic Transport Nanodevice: Asymmetric Chemical Modification of Single Nanochannels (pages 2440–2443)

      Xu Hou, Yujie Liu, Hua Dong, Fu Yang, Lin Li and Lei Jiang

      Article first published online: 29 APR 2010 | DOI: 10.1002/adma.200904268

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      Inspired by biological ion channels, the generation of artificial nanochannels has strong implications for the simulation of different processes of ionic transport as well as enhance the functionality of biological ion channels. Here, we show plasma asymmetric chemical modification approach to prepare the pH asymmetric gating nanochannel that can achieve pH control for both different ionic rectification and perfect gating function, simultaneously.

    7. Depletion of PCBM at the Cathode Interface in P3HT/PCBM Thin Films as Quantified via Neutron Reflectivity Measurements (pages 2444–2447)

      Andrew J. Parnell, Alan D. F. Dunbar, Andrew J. Pearson, Paul A. Staniec, Andrew J. C. Dennison, Hiroshi Hamamatsu, Maximilian W. A. Skoda, David G. Lidzey and Richard. A. L. Jones

      Article first published online: 20 MAY 2010 | DOI: 10.1002/adma.200903971

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      Using neutron reflectivity, self-stratification in a model P3HT/PCBM blend is observed. The as-spun and solvent-annealed films show a depletion of PCBM near the top surface and enrichment of PCBM at the substrate (see figure). Depletion of PCBM at the cathode interface in a photovoltaic device could act as a barrier to efficient electron extraction. On thermal annealing, the PCBM depleted region is eliminated; an effect that partially explains the improvement of P3HT/PCBM devices on thermal annealing.

    8. Ionic/Electronic Hybrid Materials Integrated in a Synaptic Transistor with Signal Processing and Learning Functions (pages 2448–2453)

      Qianxi Lai, Lei Zhang, Zhiyong Li, William F. Stickle, R. Stanley Williams and Yong Chen

      Article first published online: 5 MAY 2010 | DOI: 10.1002/adma.201000282

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      A synaptic transistor is fabricated by integrating ionic/electronic hybrid materials to emulate biological synapses with spike signal processing, learning, and memory functions. A potential spike generates transient ionic fluxes in a polymer layer in the transistor gate, triggering an excitatory postsynaptic current in the transistor drain. Temporally correlated pre- and post-synaptic spikes modify ions stored in the polymer, resulting in the nonvolatile modification of the transistor with spike-timing-dependent plasticity.

    9. Magnetic-Field-Assisted Electrospinning of Aligned Straight and Wavy Polymeric Nanofibers (pages 2454–2457)

      Yaqing Liu, Xinping Zhang, Younan Xia and Hong Yang

      Article first published online: 7 APR 2010 | DOI: 10.1002/adma.200903870

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      Aligned straight and wavy fibers of biodegradable poly(D,L-lactic-co-glycolic acid) (PLGA) are fabricated using a magnetic-field-assisted electrospinning method. PLGA fibrous matrices prepared by this method can guide the growth of pluripotent murine mesenchymal stem cells. While the stem cells on the randomly oriented fibers adapt pseudo-sphere-like shape, those on aligned fibers exhibit elongated morphology along the long axes (see figure).

    10. Organic Single Crystal Field-effect Transistors Based on 6H-pyrrolo[3,2–b:4,5–]bis[1,4]benzothiazine and its Derivatives (pages 2458–2462)

      Zhongming Wei, Wei Hong, Hua Geng, Chengliang Wang, Yaling Liu, Rongjin Li, Wei Xu, Zhigang Shuai, Wenping Hu, Quanrui Wang and Daoben Zhu

      Article first published online: 7 APR 2010 | DOI: 10.1002/adma.201000088

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      Single crystal effect-field transistors (SCFETs) are fabricated based on single crystal micro-ribbons of 6H-pyrrolo[3,2–b:4,5–]bis[1,4]benzothiazine and its 6-substituted derivatives (PBBTZ 1–3). High mobility (3.6 cm2 V−1 s−1) and high stability (no significant decrease in one year) are obtained from the devices. The quantum chemically calculated results on the crystals 13 (see figure) agrees well with the experimental data.

    11. Highly Non-Linear Quantum Dot Doped Nanocomposites for Functional Three-Dimensional Structures Generated by Two-Photon Polymerization (pages 2463–2467)

      Baohua Jia, Dario Buso, Joel van Embden, Jiafang Li and Min Gu

      Article first published online: 28 APR 2010 | DOI: 10.1002/adma.201000513

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      A nanocomposite consisting of a photosensitive organic–inorganic hybrid polymer functionalized with PbS quantum dots has been developed using a sol–gel process. The uniformly dispersed nanocomposite exhibits ultrahigh third-order non-linearity (–3.2 × 10−12 cm2 W−1) because of the strong quantum confinement of small-sized and narrowly distributed quantum dots. The non-linear nanocomposite has been proven to be suitable for the fabrication of 3D micro/nano photonic devices using two-photon polymerization. The fabricated photonic crystals show stop gaps with more than 60% suppression in transmission at the telecommunications wavelength region.

    12. A Highly Efficient Universal Bipolar Host for Blue, Green, and Red Phosphorescent OLEDs (pages 2468–2471)

      Ho-Hsiu Chou and Chien-Hong Cheng

      Article first published online: 5 MAY 2010 | DOI: 10.1002/adma.201000061

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      The bipolar host material BCPO (bis-4- (N-carbazolyl)phenylphosphine oxide) containing a phosphine oxide and two carbazole groups, synthesized in three steps, shows a high triplet energy gap of 3.01 eV. The material can be used as a universal host for blue, green, and red phosphorescent devices, all giving extremely high efficiencies with turn-on voltages within 3 V.

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