Advanced Materials

Cover image for Vol. 18 Issue 6

March, 2006

Volume 18, Issue 6

Pages 679–814

    1. Cover Picture: Spontaneous Emission Control in Micropillar Cavities Containing a Fluorescent Molecular Dye (Adv. Mater. 6/2006)

      A. M. Adawi, A. Cadby, L. G. Connolly, W.-C. Hung, R. Dean, A. Tahraoui, A. M. Fox, A. G. Cullis, D. Sanvitto, M. S. Skolnick and D. G. Lidzey

      Article first published online: 15 MAR 2006 | DOI: 10.1002/adma.200690025

      The fabrication of micropillar microcavities containing a fluorescent organic dye is reported. Scanning near-field optical microscopy of the luminescence from such structures (see figure and cover) confirms that a significant increase in radiative rate occurs as a result of the reduced optical-mode volume. Such structures may eventually permit efficient single-photon light sources operating at room temperature to be developed for quantum-cryptography and quantum-computing applications.

    2. Inside Front Cover: Towards See-Through Displays: Fully Transparent Thin-Film Transistors Driving Transparent Organic Light-Emitting Diodes (Adv. Mater. 6/2006)

      P. Görrn, M. Sander, J. Meyer, M. Kröger, E. Becker, H.-H. Johannes, W. Kowalsky and T. Riedl

      Article first published online: 15 MAR 2006 | DOI: 10.1002/adma.200690026

      Entirely transparent pixels composed of monolithically integrated transparent organic light-emitting diodes driven by transparent thin-film transistors are presented. With an average transmittance of more than 70 % (see figure and inside cover) in the visible part of the spectrum (400–750 nm), the presented active pixels pave the way to the realization of fully transparent active-matrix displays. Low processing temperatures mean that flexible transparent displays may be feasible.

    3. Contents: Adv. Mater. 6/2006 (pages 679–687)

      Article first published online: 15 MAR 2006 | DOI: 10.1002/adma.200690023

    4. Mechanical Reinforcement of Polymers Using Carbon Nanotubes (pages 689–706)

      J. N. Coleman, U. Khan and Y. K. Gun'ko

      Article first published online: 22 FEB 2006 | DOI: 10.1002/adma.200501851

      Thumbnail image of graphical abstract

      Mechanical reinforcement of polymers using carbon nanotubes is reviewed, where production techniques and mechanical properties of various nanotube–polymer composites are critically analyzed and compared. The current state of this research and prospects for future research and applications are discussed. The figure shows a fracture surface of a polymer–nanotube composite showing nanotube pullout.

    5. Nanoporous Membranes with Ultrahigh Selectivity and Flux for the Filtration of Viruses (pages 709–712)

      S. Y. Yang, I. Ryu, H. Y. Kim, J. K. Kim, S. K. Jang and T. P. Russell

      Article first published online: 16 FEB 2006 | DOI: 10.1002/adma.200501500

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      A double-layered nanoporous membrane suitable for virus filtration has been fabricated. The top layer has cylindrical pores with diameters of 15 nm and a narrow pore size distribution (see figure). The bottom support layer is a conventional microfiltration membrane. This asymmetric membrane completely blocks human rhinovirus type 14 (colored green) from penetrating into pores, while proteins such as bovine serum albumin (colored yellow) freely pass through the pores.

    6. Synthesis of Nanowires Using Dip-Pen Nanolithography and Biocatalytic Inks (pages 713–718)

      B. Basnar, Y. Weizmann, Z. Cheglakov and I. Willner

      Article first published online: 22 FEB 2006 | DOI: 10.1002/adma.200502320

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      Gold-nanoparticle-functionalized enzymes act as “biocatalytic inks” for the generation of metallic nanowires via dip-pen nanolithography. Deposition of nanoparticle-modified oxidases or a phosphatase followed by development with their respective substrates and metal salts results in nanowires (see figure). This concept may be extended to the generation of other nanostructures via enzyme-catalyzed particle growth.

    7. Single-Crystal Polythiophene Microwires Grown by Self-Assembly (pages 719–723)

      D. H. Kim, J. T. Han, Y. D. Park, Y. Jang, J. H. Cho, M. Hwang and K. Cho

      Article first published online: 22 FEB 2006 | DOI: 10.1002/adma.200502442

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      Single-crystal polythiophene microwires with unprecedented electrical characteristics such as low resistance (0.5 MΩ), a channel current as high as 25 μA, and well-resolved gate modulation (see figure) have been obtained by specific control over the supramolecular organization of individual polymer chains, which show preferential well-ordered interchain stacking along the wire axis. This approach offers a promising protocol for new flexible electronics.

    8. Buckling in Quasi-2D Polymers (pages 724–728)

      S. Edmondson, K. Frieda, J. E. Comrie, P. R. Onck and W. T. S. Huck

      Article first published online: 22 FEB 2006 | DOI: 10.1002/adma.200501509

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      Buckle-driven delamination and subsequent collapse of strained thin polymer films upon triggered release from the substrate is exploited to fabricate striking, well-defined ridging patterns (see figure). An analysis of these patterns is presented, including the effects of film thickness and the exterior shape of these “quasi-2D” polymer objects.

    9. Facile Generation of Fullerene Nanoparticles by Hand-Grinding (pages 729–732)

      S. Deguchi, S. Mukai, M. Tsudome and K. Horikoshi

      Article first published online: 23 FEB 2006 | DOI: 10.1002/adma.200502487

      Thumbnail image of graphical abstract

      A top-down approach to C60 nanoparticle formation by simple hand-grinding of fullerene solids in an agate mortar is described (see figure). The resulting nanoparticles are found to disperse in water with or without the aid of a dispersing agent. In contrast to previous reports, no cytotoxicity was observed for the hand-ground C60 nanoparticles.

    10. Bulk Nanocrystalline Fe3Al-Based Material Prepared by Aluminothermic Reaction (pages 733–737)

      P. La, J. Yang, D. J. H. Cockayne, W. Liu, Q. Xue and Y. Li

      Article first published online: 22 FEB 2006 | DOI: 10.1002/adma.200501684

      Thumbnail image of graphical abstract

      Excellent mechanical properties are often found in bulk nanocrystalline materials. However, it is a major challenge to find a method of processing that is convenient, has a low cost, and a capacity to be scaled up. Bulk nanocrystalline Fe3Al-based material with a MnAl1.11S1.89 contamination phase has been successfully synthesized (see figure) by making use of a simple aluminothermic reaction route.

    11. Towards See-Through Displays: Fully Transparent Thin-Film Transistors Driving Transparent Organic Light-Emitting Diodes (pages 738–741)

      P. Görrn, M. Sander, J. Meyer, M. Kröger, E. Becker, H.-H. Johannes, W. Kowalsky and T. Riedl

      Article first published online: 15 MAR 2006 | DOI: 10.1002/adma.200501957

      Thumbnail image of graphical abstract

      Entirely transparent pixels composed of monolithically integrated transparent organic light-emitting diodes driven by transparent thin-film transistors are presented. With an average transmittance of more than 70 % (see figure and inside cover) in the visible part of the spectrum (400–750 nm), the presented active pixels pave the way to the realization of fully transparent active-matrix displays. Low processing temperatures mean that flexible transparent displays may be feasible.

    12. Spontaneous Emission Control in Micropillar Cavities Containing a Fluorescent Molecular Dye (pages 742–747)

      A. M. Adawi, A. Cadby, L. G. Connolly, W.-C. Hung, R. Dean, A. Tahraoui, A. M. Fox, A. G. Cullis, D. Sanvitto, M. S. Skolnick and D. G. Lidzey

      Article first published online: 22 FEB 2006 | DOI: 10.1002/adma.200502099

      Thumbnail image of graphical abstract

      The fabrication of micropillar microcavities containing a fluorescent organic dye is reported. Scanning near-field optical microscopy of the luminescence from such structures (see figure and cover) confirms that a significant increase in radiative rate occurs as a result of the reduced optical-mode volume. Such structures may eventually permit efficient single-photon light sources operating at room temperature to be developed for quantum-cryptography and quantum-computing applications.

    13. Polymerization Initiated by Inherent Free Radicals on Nanoparticle Surfaces: A Simple Method of Obtaining Ultrastable (ZnO)Polymer Core–Shell Nanoparticles with Strong Blue Fluorescence (pages 748–751)

      H.-M. Xiong, Z.-D. Wang and Y.-Y. Xia

      Article first published online: 15 MAR 2006 | DOI: 10.1002/adma.200501899

      Thumbnail image of graphical abstract

      Strong blue fluorescence—with a quantum yield over 80 % (see figure)—of ultrastable (ZnO)polymer core–shell nanoparticles is suggested to arise by a luminescence mechanism different from that for conventional ZnO nanoparticles. The stable particles are produced by methacrylic-group-modified ZnO nanoparticles reacting with liquid monomers, the polymerization being initiated by free radicals pre-existing on the ZnO nanoparticle surfaces.

    14. Compressive Behavior of a Zr-Based Metallic Glass at Cryogenic Temperatures (pages 752–754)

      H. Li, C. Fan, K. Tao, H. Choo and P. K. Liaw

      Article first published online: 21 FEB 2006 | DOI: 10.1002/adma.200501990

      Thumbnail image of graphical abstract

      Cold compression: The compressive behavior of the as-cast fully amorphous Zr57.4Cu17.9Ni13.4Al10.3Nb1 alloy has been conducted at room temperature (298 K) and at liquid-nitrogen temperature (77 K). It is found that at cryogenic temperatures, at the same strain rate, the strength of the material increases remarkably without any loss of ductility (see figure).

    15. Ordered Array of Gold Nanoshells Interconnected with Gold Nanotubes Fabricated by Double Templating (pages 755–759)

      W. Dong, H. Dong, Z. Wang, P. Zhan, Z. Yu, X. Zhao, Y. Zhu and N. Ming

      Article first published online: 15 MAR 2006 | DOI: 10.1002/adma.200501304

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      Ordered interconnected gold nanoshells and nanotubes (see figure) are made by electroless plating in a macroporous polymer replicated from a non-close-packed silica colloidal crystal. The size of the gold nanoshells and nanotubes can be altered by varying the sintering and etching conditions for the silica template. A remarkable modulation in optical reflectivity resulting from surface plasmon excitation has been observed in the microstructure.

    16. Highly Ordered Platinum Nanodot Arrays with Cubic Symmetry in Mesoporous Thin Films (pages 760–762)

      Y. Kumai, H. Tsukada, Y. Akimoto, N. Sugimoto, Y. Seno, A. Fukuoka, M. Ichikawa and S. Inagaki

      Article first published online: 15 MAR 2006 | DOI: 10.1002/adma.200502184

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      Highly ordered Pt nanodot arrays with cubic symmetry are synthesized by simple immersion of mesoporous silica thin films into a Pt precursor solution followed by photoreduction. Two types of cages of mesoporous thin films have been fully filled with Pt nanoparticles approximately 4 nm in size, and an exceptionally well-ordered cubic lattice array of nanodots has been obtained (see figure).

    17. Crystalline WO3 Nanoparticles for Highly Improved Electrochromic Applications (pages 763–766)

      S.-H. Lee, R. Deshpande, P. A. Parilla, K. M. Jones, B. To, A. H. Mahan and A. C. Dillon

      Article first published online: 15 MAR 2006 | DOI: 10.1002/adma.200501953

      Thumbnail image of graphical abstract

      Electrochromic materials change optical properties (darken/lighten) in the presence of a small electric potential difference, making them suitable for many applications. By fabricating porous films from crystalline WO3 nanoparticles (see figure), this state-of-the-art technology has been profoundly advanced. Significantly enhanced durability, increased charge insertion, and better kinetics have been demonstrated with an economical deposition process suitable for large-area applications.

    18. One-Step Solution-Immersion Process for the Fabrication of Stable Bionic Superhydrophobic Surfaces (pages 767–770)

      S. Wang, L. Feng and L. Jiang

      Article first published online: 15 MAR 2006 | DOI: 10.1002/adma.200501794

      Thumbnail image of graphical abstract

      A simple morphogenesis technique for fabricating stable bionic superhydrophobic surfaces at ambient temperature using copper as a model system is presented. The resulting flowerlike cluster coating of copper fatty acid carboxylates (see figure) has a high contact angle of about 162°. This study opens up new avenues for the industrial fabrication of superhydrophobic surfaces that may be useful in a wide variety of applications.

    19. High-Temperature Lasing Characteristics of ZnO Epilayers (pages 771–774)

      H. D. Li, S. F. Yu, S. P. Lau, E. S. P. Leong, H. Y. Yang, T. P. Chen, A. P. Abiyasa and C. Y. Ng

      Article first published online: 15 MAR 2006 | DOI: 10.1002/adma.200501693

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      Coherent random lasing has been observed inside nanostructured ZnO epilayers up to 570 K. The corresponding characteristic temperature is ∼127 K. The confinement of excited carriers inside ZnO grains and the size flexibility of the random cavities maintain optical gain at high temperatures. This unique behavior will lead to the development of novel ZnO UV lasers tunable over a wide wavelength range by controlling the substrate temperature.

    20. Chiroptical Properties Induced in Chiral Photonic-Bandgap Liquid Crystals Leading to a Highly Efficient Laser-Feedback Effect (pages 775–780)

      S. Furumi and Y. Sakka

      Article first published online: 22 FEB 2006 | DOI: 10.1002/adma.200501849

      Thumbnail image of graphical abstract

      Highly efficient lasing action is obtained by exploiting the chiroptical characteristics of the ground and excited states of an achiral fluorescent dye doped in a cholesteric liquid crystal (CLC) medium (see figure). The highly efficient lasing action from the oblique dye-doped CLC cell is produced by tuning the ellipticity angle of the excitation beam while taking into consideration the molecular helical sense of the cholesteric host.

      Corrected by:

      Correction: Chiroptical Properties Induced in Chiral Photonic-Bandgap Liquid Crystals Leading to a Highly Efficient Laser-Feedback Effect

      Vol. 18, Issue 11, 1344, Article first published online: 29 MAY 2006

    21. Synthesis of Mesostructured Copper Sulfide by Cation Exchange and Liquid-Crystal Templating (pages 781–784)

      C. R. Lubeck, T. Y.-J. Han, A. E. Gash, J. H. Satcher Jr. and F. M. Doyle

      Article first published online: 21 FEB 2006 | DOI: 10.1002/adma.200501653

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      Supermolecular assembly techniques combined with the cation exchange of nanoparticles transforms mesostructured CdS into mesostructured CuS (see figure). The resulting materials retain the overall integrity of the original mesostructured material after the cation-exchange process.

    22. Alignment of Carbon Nanotube Additives for Improved Performance of Magnesium Diboride Superconductors (pages 785–788)

      S. X. Dou, W. K. Yeoh, O. Shcherbakova, D. Wexler, Y. Li, Z. M. Ren, P. Munroe, S. K. Chen, K. S. Tan, B. A. Glowacki and J. L. MacManus-Driscoll

      Article first published online: 22 FEB 2006 | DOI: 10.1002/adma.200501617

      Thumbnail image of graphical abstract

      A method for aligning carbon nanotubes (CNTs) in CNT–MgB2 superconductor composite wires through a readily scalable drawing technique is described. The aligned CNT-doped MgB2 wires show an enhancement in magnetic critical current density by more than an order of magnitude in high magnetic fields compared to undoped wires. The arrows in the figure indicate CNTs in the composite.

    23. Design Rules for Donors in Bulk-Heterojunction Solar Cells—Towards 10 % Energy-Conversion Efficiency (pages 789–794)

      M. C. Scharber, D. Mühlbacher, M. Koppe, P. Denk, C. Waldauf, A. J. Heeger and C. J. Brabec

      Article first published online: 22 FEB 2006 | DOI: 10.1002/adma.200501717

      Thumbnail image of graphical abstract

      For bulk-heterojunction photovoltaic cells fabricated from conjugated polymers and a fullerene derivative, the relation between the open-circuit voltage (Voc) and the oxidation potential for different conjugated polymers is studied. A linear relation between Voc and the oxidation potential is found (see figure). Based on this relation, the energy-conversion efficiency of a bulk-heterojunction solar cell is derived as a function of the bandgap and the energy levels of the conjugated polymer.

    24. Nanoporous Protein Particles Through Templating Mesoporous Silica Spheres (pages 795–800)

      Y. Wang and F. Caruso

      Article first published online: 21 FEB 2006 | DOI: 10.1002/adma.200501901

      Thumbnail image of graphical abstract

      Sequential assembly of protein and polyelectrolyte in mesoporous silica (MS) spheres leads to the formation of nanoporous protein particles (NPPs); the MS templates are removed after the fabrication process (see figure). The NPPs based on catalase show excellent biological activity, with up to 57 % of the activity retained. This strategy offers a novel and effective method of preparing bioactive NPPs of diverse composition, particle size, and shape.

    25. A Method for the Fabrication of Monodisperse Hollow Silica Spheres (pages 801–806)

      M. Chen, L. Wu, S. Zhou and B. You

      Article first published online: 23 FEB 2006 | DOI: 10.1002/adma.200501528

      Thumbnail image of graphical abstract

      A novel technique for fabricating hollow silica spheres (see figure) via a one-step process is described. The positively charged template polystyrene particles are “dissolved” subsequently, even synchronously, as the silica layer is formed in the same medium. Hollow silica spheres are formed, and neither additional dissolution nor calcination is needed during the whole process. The scale bar represents 1 μm.

    26. Room Temperature Synthesis of Ferroelectric Barium Titanate Nanoparticles Using Peptide Nanorings as Templates (pages 807–811)

      N. Nuraje, K. Su, A. Haboosheh, J. Samson, E. P. Manning, N.-l. Yang and H. Matsui

      Article first published online: 15 MAR 2006 | DOI: 10.1002/adma.200501340

      Thumbnail image of graphical abstract

      Tetragonal ferroelectric BaTiO3 nanoparticles are hydrolyzed inside peptide-ring templates at room temperature and pressure (see figure). The sizes of the monodisperse BaTiO3 nanoparticles are controlled between 6 and 12 nm by varying the cavity size of the nanorings as a function of pH. The nanoparticles possess switching behavior under the influence of external electric fields.

    27. Author Index and Subject Index Adv. Mater. 6/2006 (pages 813–814)

      Article first published online: 15 MAR 2006 | DOI: 10.1002/adma.200690024

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