Advanced Materials

Cover image for Vol. 24 Issue 9

March 2, 2012

Volume 24, Issue 9

Pages 1137–1275

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Masthead
    6. Contents
    7. Progress Report
    8. Frontispiece
    9. Communications
    1. Organic Light-Emitting Diodes: Solving Efficiency–Stability Tradeoff in Top-Emitting Organic Light-Emitting Devices by Employing Periodically Corrugated Metallic Cathode (Adv. Mater. 9/2012) (page 1137)

      Yu Jin, Jing Feng, Xu-Lin Zhang, Yan-Gang Bi, Yu Bai, Lu Chen, Tian Lan, Yue-Feng Liu, Qi-Dai Chen and Hong-Bo Sun

      Version of Record online: 24 FEB 2012 | DOI: 10.1002/adma.201290042

      Thumbnail image of graphical abstract

      The traditional compromise between stability and efficiency in top-emitting organic light-emitting devices has been resolved by using periodically corrugated metallic cathodes. J. Feng, H.-B. Sun, and co-workers demonstrate on page 1187 how this new design causes cross-coupling of the surface plasmon polaritons and the microcavity modes. This design removes the requirement for the cathode material to be vanishingly thin, allowing thicker cathode layers, which leads to higher efficiencies and longer device lifetimes.

  2. Inside Front Cover

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Masthead
    6. Contents
    7. Progress Report
    8. Frontispiece
    9. Communications
    1. Patterning: Direct Transfer Patterning of Electrically Small Antennas onto Three-Dimensionally Contoured Substrates (Adv. Mater. 9/2012) (page 1138)

      Carl Pfeiffer, Xin Xu, Stephen R. Forrest and Anthony Grbic

      Version of Record online: 24 FEB 2012 | DOI: 10.1002/adma.201290043

      Thumbnail image of graphical abstract

      A process to stamp conductors onto contoured surfaces is reported by S. R. Forrest, A. Grbic, and co-workers on page 1166. This process has the potential to provide an inexpensive and rapid method to print metallic patterns onto arbitrarily contoured substrates, which has extensive applications. Here, electrically small antennae are printed onto dielectric hemispheres. These antennae offer bandwidths approaching the fundamental limit, while maintaining some of the highest reported efficiencies to date. Cover design by C. Pfeiffer and P. Haley.

  3. Back Cover

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Masthead
    6. Contents
    7. Progress Report
    8. Frontispiece
    9. Communications
    1. Batteries: The Role of AlF3 Coatings in Improving Electrochemical Cycling of Li-Enriched Nickel-Manganese Oxide Electrodes for Li-Ion Batteries (Adv. Mater. 9/2012) (page 1276)

      Yang-Kook Sun, Min-Joon Lee, Chong S. Yoon, Jusef Hassoun, Khalil Amine and Bruno Scrosati

      Version of Record online: 24 FEB 2012 | DOI: 10.1002/adma.201290044

      Thumbnail image of graphical abstract

      Y.-K. Sun, C. S. Yoon, B. Scrosati and co-workers report on page 1192 the role of an AlF3-coating layer on Li-enriched cathode materials, which not only improves electrochemical performances but also thermal stability. These improvements are attributed to the trans-formation of the initial layer (Li2MnO3) to a spinel phase, induced by the Li chemical-leaching effect of the AlF3 coating layer. The spinel phase transferred from the layer on the Li-enriched electrodes is able to negate the previous shortcomings of these designs.

  4. Masthead

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Masthead
    6. Contents
    7. Progress Report
    8. Frontispiece
    9. Communications
    1. Masthead: (Adv. Mater. 9/2012)

      Version of Record online: 24 FEB 2012 | DOI: 10.1002/adma.201290045

  5. Contents

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Masthead
    6. Contents
    7. Progress Report
    8. Frontispiece
    9. Communications
  6. Progress Report

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Masthead
    6. Contents
    7. Progress Report
    8. Frontispiece
    9. Communications
    1. Operational Stability of Organic Field-Effect Transistors (pages 1146–1158)

      Peter A. Bobbert, Abhinav Sharma, Simon G. J. Mathijssen, Martijn Kemerink and Dago M. de Leeuw

      Version of Record online: 2 FEB 2012 | DOI: 10.1002/adma.201104580

      Thumbnail image of graphical abstract

      In an organic field-effect transistor redox reactions at the surface of the gate dielectric involving water can lead to conversion of holes in the accumulation layer into protons. The protons diffuse into the gate dielectric and cause a shift of the threshold voltage of the transistor.

  7. Frontispiece

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Masthead
    6. Contents
    7. Progress Report
    8. Frontispiece
    9. Communications
    1. Ferroelectric Nanotubes: Free-Standing Ferroelectric Nanotubes Processed via Soft-Template Infiltration (Adv. Mater. 9/2012) (page 1159)

      Ashley Bernal, Alexander Tselev, Sergei Kalinin and Nazanin Bassiri-Gharb

      Version of Record online: 24 FEB 2012 | DOI: 10.1002/adma.201290041

      Thumbnail image of graphical abstract

      The image depicts an array of free-standing ferroelectric perovskite PbZrTiO nanotube islands, processed with soft-template infiltration using a solution precursor. Such high aspect ratio nanotube/pillar arrays, described on page 1160 by N. Bassiri-Gharb and co-workers, find diverse application in actively tunable photonic and phononic crystals, terahertz emitters, energy harvesters, and nanoelectromechanical sensors, actuators, and transducers.

  8. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Masthead
    6. Contents
    7. Progress Report
    8. Frontispiece
    9. Communications
    1. Free-Standing Ferroelectric Nanotubes Processed via Soft-Template Infiltration (pages 1160–1165)

      Ashley Bernal, Alexander Tselev, Sergei Kalinin and Nazanin Bassiri-Gharb

      Version of Record online: 26 JAN 2012 | DOI: 10.1002/adma.201103993

      Thumbnail image of graphical abstract

      A new nano-manufacturing method for the creation of high aspect-ratio ferroelectric (PbZr0.52Ti0.48O3) nanostructures by use of polymeric templates is presented. The ferroelectric response is characterized by band-excitation PFM, supporting the high quality of the nanostructures. Piezoelectric size effects for ferroelectric materials are reported for the first time in nanotube configuration (critical thickness ∼15 nm) and compared to thin films’ response.

    2. Direct Transfer Patterning of Electrically Small Antennas onto Three-Dimensionally Contoured Substrates (pages 1166–1170)

      Carl Pfeiffer, Xin Xu, Stephen R. Forrest and Anthony Grbic

      Version of Record online: 31 JAN 2012 | DOI: 10.1002/adma.201104290

      Thumbnail image of graphical abstract

      A direct transfer patterning process is presented that allows metallic patterns to be stamped onto a contoured substrate. This process was used to make some of the most efficient electrically small antennas to date, while maintaining bandwidths approaching the physical limit.

    3. Control of Efficiency, Brightness, and Recombination Zone in Light-Emitting Field Effect Transistors (pages 1171–1175)

      Ben B.Y. Hsu, Chunhui Duan, Ebinazar B. Namdas, Andrea Gutacker, Jonathan D. Yuen, Fei Huang, Yong Cao, Guillermo C. Bazan, Ifor D. W. Samuel and Alan J. Heeger

      Version of Record online: 26 JAN 2012 | DOI: 10.1002/adma.201103513

      Thumbnail image of graphical abstract

      The split-gate light emitting field effect transistors (SG-LEFETs) demonstrate a new strategy for ambipolar LEFETs to achieve high brightness and efficiency simultaneously. The SG architecture forces largest quantity of opposite charges on Gate 1 and Gate 2 area to meet in the center of the channel. By actively and independently controlling current injection from separated gate electrodes within transporting channel, high brightness can be obtained in the largest injection current regime with highest efficiency.

    4. A Soft Approach to Encapsulate Sulfur: Polyaniline Nanotubes for Lithium-Sulfur Batteries with Long Cycle Life (pages 1176–1181)

      Lifen Xiao, Yuliang Cao, Jie Xiao, Birgit Schwenzer, Mark H. Engelhard, Laxmikant V. Saraf, Zimin Nie, Gregory J. Exarhos and Jun Liu

      Version of Record online: 26 JAN 2012 | DOI: 10.1002/adma.201103392

      Thumbnail image of graphical abstract

      A novel vulcanized polyaniline nanotube/sulfur composite was prepared successfully via an in situ vulcanization process by heating a mixture of polyaniline nanotube and sulfur at 280 °C. The electrode could retain a discharge capacity of 837 mAh g−1 after 100 cycles at a 0.1 C rate and manifested 76% capacity retention up to 500 cycles at a 1 C rate.

    5. Silicon Filaments in Silicon Oxide for Next-Generation Photovoltaics (pages 1182–1186)

      Peter Cuony, Duncan T. L. Alexander, Ivan Perez-Wurfl, Matthieu Despeisse, Gregory Bugnon, Mathieu Boccard, Thomas Söderström, Aïcha Hessler-Wyser, Cécile Hébert and Christophe Ballif

      Version of Record online: 30 JAN 2012 | DOI: 10.1002/adma.201104578

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      Nanometer wide silicon filaments embedded in an amorphous silicon oxide matrix are grown at low temperatures over a large area. The optical and electrical properties of these mixed-phase nanomaterials can be tuned independently, allowing for advanced light management in high efficiency thin-film silicon solar cells and for band-gap tuning via quantum confinement in third-generation photovoltaics.

    6. Solving Efficiency–Stability Tradeoff in Top-Emitting Organic Light-Emitting Devices by Employing Periodically Corrugated Metallic Cathode (pages 1187–1191)

      Yu Jin, Jing Feng, Xu-Lin Zhang, Yan-Gang Bi, Yu Bai, Lu Chen, Tian Lan, Yue-Feng Liu, Qi-Dai Chen and Hong-Bo Sun

      Version of Record online: 26 JAN 2012 | DOI: 10.1002/adma.201103397

      Thumbnail image of graphical abstract

      The introduction of a periodic corrugation into TOLEDs is demonstrated to be effective in relieving the tradeoff between device stability and efficiency, through the cross coupling of the SPPs associated with the Ag cathode and the microcavity modes. The thickness of the Ag cathode for the corrugated TOLEDs was increased from 20 to 45 nm, and both the device lifetime and efficiency are significantly improved. The figure shows a schematic cross section of a red TOLED with periodic microstructure and an operating TOLED with both corrugated and planar area.

    7. The Role of AlF3 Coatings in Improving Electrochemical Cycling of Li-Enriched Nickel-Manganese Oxide Electrodes for Li-Ion Batteries (pages 1192–1196)

      Yang-Kook Sun, Min-Joon Lee, Chong S. Yoon, Jusef Hassoun, Khalil Amine and Bruno Scrosati

      Version of Record online: 24 FEB 2012 | DOI: 10.1002/adma.201104106

      Thumbnail image of graphical abstract

      A Li[Li0.19Ni0.16Co0.08Mn0.57]O2 cathode was coated with AlF3 on the surface. The AlF3-coating enhanced the overall electrochemical characteristics of the electrode while overcoming the typical shortcomings of lithium-enriched cathodes. This improvement was attributed to the transformation of the initial electrode layer to a spinel phase, induced by the Li chemical leaching effect of the AlF3 coating layer.

    8. Regenerable Resistive Switching in Silicon Oxide Based Nanojunctions (pages 1197–1201)

      Massimiliano Cavallini, Zahra Hemmatian, Alberto Riminucci, Mirko Prezioso, Vittorio Morandi and Mauro Murgia

      Version of Record online: 24 FEB 2012 | DOI: 10.1002/adma.201104301

      Thumbnail image of graphical abstract

      A nanomemristor based on SiO2 is fabricated in situ with spatial control at the nanoscale. The proposed system exhibits peculiar properties such as the possibility to be regenerated after being stressed or damaged and the possibility to expose the metal and the oxide interfaces by removing the top electrodes.

    9. Enhancement of Photocurrent in Ferroelectric Films Via the Incorporation of Narrow Bandgap Nanoparticles (pages 1202–1208)

      Xiaoluan Yang, Xiaodong Su, Mingrong Shen, Fengang Zheng, Yu Xin, Lu Zhang, Muchuan Hua, Yajie Chen and V. G. Harris

      Version of Record online: 26 JAN 2012 | DOI: 10.1002/adma.201104078

      Thumbnail image of graphical abstract

      A novel nanostructured ferroelectric photovoltaic material, consisting of the ferroelectric lead zirconate titanate (PZT) film and Ag2O semiconductor nanoparticles of comparatively narrow bandgap, has demonstrated a remarkable enhancement in the photovoltaic effects and the highest light-electricity conversion efficiency among those PZT-based photodiodes previously reported. This work sheds light on the design and enhanced performance of new optoelectronic and solar energy devices.

    10. Enhancement of Ferroelectric Polarization Stability by Interface Engineering (pages 1209–1216)

      H. Lu, X. Liu, J. D. Burton, C.-W. Bark, Y. Wang, Y. Zhang, D. J. Kim, A. Stamm, P. Lukashev, D. A. Felker, C. M. Folkman, P. Gao, M. S. Rzchowski, X. Q. Pan, C.-B. Eom, E. Y. Tsymbal and A. Gruverman

      Version of Record online: 26 JAN 2012 | DOI: 10.1002/adma.201104398

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      By using theoretical predictions based on first-principle calculations, we explore an interface engineering approach to stabilize polarization states in ferroelectric heterostructures with a thickness of just several nanometers.

    11. Enhanced Electrochromism in Gyroid-Structured Vanadium Pentoxide (pages 1217–1221)

      Maik R. J. Scherer, Li Li, Pedro M. S. Cunha, Oren A. Scherman and Ullrich Steiner

      Version of Record online: 30 JAN 2012 | DOI: 10.1002/adma.201104272

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      Manufacturing V2O5 in a 3D periodic highly interconnected gyroid structure on the 10 nm length scale is shown to lead to a significant electrochromic performance enhancement. The structured devices surpass previous inorganic electrochromic materials in all relevant parameters: the switching speed, coloration contrast, and composite coloration efficiency. In particular, the 85 ms switching speed lies within a factor of two of video rate. Enhanced ion intercalation into the gyroid morphology can be extended to other transition-metal oxides and is therefore promising for lithium ion batteries, supercapacitors, and sensors.

    12. Aqueous Dye-Sensitized Solar Cell Electrolytes Based on the Ferricyanide–Ferrocyanide Redox Couple (pages 1222–1225)

      Torben Daeneke, Yu Uemura, Noel W. Duffy, Attila J. Mozer, Nagatoshi Koumura, Udo Bach and Leone Spiccia

      Version of Record online: 30 JAN 2012 | DOI: 10.1002/adma.201104837

      Thumbnail image of graphical abstract

      Solar energy conversion efficiencies of over 4% have been achieved in DSCs constructed with aqueous electrolytes based on the ferricyanide–ferrocyanide redox couple, thereby avoiding the use of expensive, flammable and toxic solvents. This paradigm shift was made possible by the use of a hydrophobic organic carbazole dye.

    13. Mn2+ Dopant-Controlled Synthesis of NaYF4:Yb/Er Upconversion Nanoparticles for in vivo Imaging and Drug Delivery (pages 1226–1231)

      Gan Tian, Zhanjun Gu, Liangjun Zhou, Wenyan Yin, Xiaoxiao Liu, Liang Yan, Shan Jin, Wenlu Ren, Gengmei Xing, Shoujian Li and Yuliang Zhao

      Version of Record online: 27 JAN 2012 | DOI: 10.1002/adma.201104741

      Thumbnail image of graphical abstract

      Pure dark red emission (650–670nm) of NaYF4:Yb/Er upconversion nanoparticles (UCNPs) is achieved by manganese ions (Mn2+) doping. In addition, the Mn2+- doping can also control the crystalline phase and size of the resulting UCNPs simultaneously. Drug delivery studies suggest the promise of these UCNPs as drug carriers for intracellular drug delivery and eventually as a multifunctional nanoplatform for simultaneous diagnosis and therapy.

    14. Tuning the Properties of ZnO, Hematite, and Ag Nanoparticles by Adjusting the Surface Charge (pages 1232–1237)

      Jianhui Zhang, Guanjun Dong, Aaron Thurber, Yayi Hou, Min Gu, Dmitri A. Tenne, C. B. Hanna and Alex Punnoose

      Version of Record online: 2 FEB 2012 | DOI: 10.1002/adma.201104535

      Thumbnail image of graphical abstract

      A poly (acryl acid) (PAA) post-treatment method is performed to modify the surface charge of ZnO nanospheres, hematite nanocubes, and Ag nanoprisms from highly positive to very negative by adjusting the PAA concentration, to and greatly modify their photoluminescence, cytotoxicity, magnetism, and surface plasmon resonance. This method provides a general way to tune the nanoparticle properties for broad physicochemical and biological applications.

    15. Real-Time Ion-Flux Imaging in the Growth of Micrometer-Scale Structures and Membranes (pages 1238–1242)

      Balazs Nemeth, Mark D. Symes, Antoine G. Boulay, Christoph Busche, Geoffrey J. T. Cooper, David R. S. Cumming and Leroy Cronin

      Version of Record online: 30 JAN 2012 | DOI: 10.1002/adma.201104345

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      Real-time ion flux imaging: an ion-sensitive field-effect transistor (ISFET) array is coupled with optical microscopy to image the growth of, and ion flux through, micrometer-scale tubes and membranes built from polyoxometalate clusters. The correlation between the optical and ionic imaging data is excellent, showcasing the use of ISFET arrays for high-resolution spatial and temporal mapping of ionic movements.

    16. Microstructuring of Polypyrrole by Maskless Direct Femtosecond Laser Ablation (pages 1243–1246)

      Kenneth K.C. Lee, Peter R. Herman, Tina Shoa, Moez Haque, John D.W. Madden and Victor X.D. Yang

      Version of Record online: 31 JAN 2012 | DOI: 10.1002/adma.201104170

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      Ultrafast laser micromachining was optimized for microstructuring polypyrrole as a facile new approach towards tailoring electrochemical and mechanical responses desirable for microactuator, sensors, neural probing, and nerve conduit applications. Laser perforation of high-density and high aspect ratio through-holes generated greater than 5-fold increase in surface area. The flexible machining technique offers micron-size resolution and fast prototyping capability for optimizing properties and opening new directions for polypyrrole-based devices.

    17. Controlled Ambipolar Charge Transport Through a Self-Assembled Gold Nanoparticle Monolayer (pages 1247–1251)

      Ye Zhou, Su-Ting Han, Zong-Xiang Xu and V. A. L. Roy

      Version of Record online: 2 FEB 2012 | DOI: 10.1002/adma.201104375

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      An active mechanism for controlling ambipolar charge transport is developed based on self-assembled monolayers of gold nanoparticles. Electron and hole currents are manipulated by controlling the gate bias in order to overcome the intrinsic material limitations. The endurance and retention measurements confirm that this method exhibits good electrical reliability and stability. This solution process approach has potential for applications in large-area printed electronic devices.

    18. Two-Dimensional Polymer as a Mask for Surface Nanopatterning (pages 1252–1254)

      Sylvain Clair, Oualid Ourdjini, Mathieu Abel and Louis Porte

      Version of Record online: 1 FEB 2012 | DOI: 10.1002/adma.201200063

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      NaCl islands are used as a sacrificial layer to selectively deposit a boronic acid based two-dimensional polymer. The nanostructured polymer layer can be used as a negative mask to create Fe islands in a nanolithography mimicking process.

    19. Reversible Tuning Luminescent Color and Emission Intensity: A Dipeptide-Based Light-Emitting Material (pages 1255–1261)

      Ming-Jun Teng, Xin-Ru Jia, Shuang Yang, Xiao-Fang Chen and Yen Wei

      Version of Record online: 2 FEB 2012 | DOI: 10.1002/adma.201104592

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      A smart luminescent material whose emission color and emission intensity can be separately modulated by external force is demonstrated. The rational manipulation of rich noncovalent interactions and fluorophore packing style promotes an in-depth understanding between supramolecular structure and photophysical property and offers an effective strategy to modulate the light-emitting property in a predicative way.

    20. Thermodynamic Imbalance, Surface Energy, and Segregation Reveal the True Origin of Nanotube Synthesis (pages 1262–1275)

      S. Noor Mohammad

      Version of Record online: 6 FEB 2012 | DOI: 10.1002/adma.201103576

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      Extensive analyses of thermodynamic imbalance, surface energy, and segregation of nanotubes on nanoparticle surfaces are performed. A model for surface energy i developed. In addition, nanotube growth both by vapor-phase and solid-phase mechanisms is described. Segregation of the nanotube species to the periphery of the nanoparticle, the creation of an amorphous shell at this periphery, a droplet created in this shell, and the mediation of this droplet for supersaturation and nucleation of the nanotube species may be the true causes of nanotube growth.

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