Advanced Materials

Cover image for Vol. 17 Issue 20

October, 2005

Volume 17, Issue 20

Pages 2397–2516

    1. Cover Picture: Closing the Gap Between Self-Assembly and Microsystems Using Self-Assembly, Transfer, and Integration of Particles (Adv. Mater. 20/2005)

      T. Kraus, L. Malaquin, E. Delamarche, H. Schmid, N. D. Spencer and H. Wolf

      Article first published online: 7 OCT 2005 | DOI: 10.1002/adma.200590104

      Self-assembly, transfer, and integration of particles is achieved by combining self-assembly processes with an adhesion cascade (see Figure). This process complements and enhances existing fabrication methods as it allows the integration of particles into planar devices. Moreover, it is versatile in terms of particle size and materials, and can create arbitrary particle arrangements with functional particle–substrate connections.

    2. Inside Front Cover: Redox-Tunable Defects in Colloidal Photonic Crystals (Adv. Mater. 20/2005)

      F. Fleischhaker, A. C. Arsenault, Z. Wang, V. Kitaev, F. C. Peiris, G. von Freymann, I. Manners, R. Zentel and G. A. Ozin

      Article first published online: 7 OCT 2005 | DOI: 10.1002/adma.200590105

      Reversible tuning of an intragap transmitting state induced by redox cycling is accomplished using a redox-active polyelectrolyte multilayer planar defect embedded in a colloidal photonic crystal (CPC). The wavelength position of the defect state can be changed by changing the oxidation state of the ferrocene moieties in the polymer backbone (see Figure). This could find applications in electrochemically tunable microcavities and CPC-based laser sources.

    3. Contents: Adv. Mater. 20/2005 (pages 2397–2405)

      Article first published online: 7 OCT 2005 | DOI: 10.1002/adma.200590100

    4. You have free access to this content
      More, Better, Faster... (pages 2407–2409)

      E. Levy

      Article first published online: 7 OCT 2005 | DOI: 10.1002/adma.200502009

      The pressure to publish is borne by journals as well as by research scientists. The Editor discusses meeting the challenge of an ever-increasing number of manuscript submissions while simultaneously improving the quality of the journal and reducing publication times.

    5. Device Physics of Solution-Processed Organic Field-Effect Transistors (pages 2411–2425)

      H. Sirringhaus

      Article first published online: 15 SEP 2005 | DOI: 10.1002/adma.200501152

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      Field-effect transistors based on solution-processible organic semiconductors have experienced impressive improvements in both performance (see Figure) and reliability in recent years and are being developed for applications in printable electronics on flexible substrates. This article reviews their underlying materials, charge transport, and device physics, with a particular focus on what can be learnt about the electronic properties of active, organic semiconductor/dielectric heterointerfaces from studying such devices.

    6. Ion-Beam-Assisted Lift-Off Technique for Three-Dimensional Micromachining of Freestanding Single-Crystal Diamond (pages 2427–2430)

      P. Olivero, S. Rubanov, P. Reichart, B. C. Gibson, S. T. Huntington, J. Rabeau, A. D. Greentree, J. Salzman, D. Moore, D. N. Jamieson and S. Prawer

      Article first published online: 1 SEP 2005 | DOI: 10.1002/adma.200500752

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      The machining of 3D microstructures in single-crystal artificial diamond is demonstrated with a focused ion beam (FIB)-assisted lift-off technique. A sacrificial buried layer is created with MeV ion implantation, followed by patterning of selected regions with the FIB technique; the sacrificial layer is then selectively etched, leaving 3D free-standing microstructures in the bulk (see Figure). Using this fabrication technique, light waveguiding through a microstructure in single-crystal diamond is demonstrated for the first time.

    7. Control of Carrier Density by a Solution Method in Carbon-Nanotube Devices (pages 2430–2434)

      T. Takenobu, T. Kanbara, N. Akima, T. Takahashi, M. Shiraishi, K. Tsukagoshi, H. Kataura, Y. Aoyagi and Y. Iwasa

      Article first published online: 13 SEP 2005 | DOI: 10.1002/adma.200500759

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      A new method for controlling the hole density in single-walled carbon nanotube field-effect transistors (SWCNT-FETs) by solution-based chemical doping is presented. The use of organic molecules that adsorb onto SWCNTs from solution is investigated. The transfer characteristics of the SWCNT-FETs exhibit continuous and precise shifts in threshold voltages (see Figure) upon doping with F4TCNQ molecules, even in air.

    8. Fabrication of a Photoelectronic Device by Direct Chemical Binding of the Photosynthetic Reaction Center Protein to Metal Surfaces (pages 2434–2437)

      L. Frolov, Y. Rosenwaks, C. Carmeli and I. Carmeli

      Article first published online: 6 SEP 2005 | DOI: 10.1002/adma.200500295

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      Photosystem I (PS I), a multi-subunit protein–chlorophyll complex that mediates vectorial, light-induced electron transfer has been self-assembled as an oriented monolayer on a solid metal surface. Unique cysteine mutants are induced for the attachment of PS I through the formation of sulfide bonds. A photopotential of approximately +1 V is observed (see Figure) for single trimer molecules or the monolayer continuum.

    9. Closing the Gap Between Self-Assembly and Microsystems Using Self-Assembly, Transfer, and Integration of Particles (pages 2438–2442)

      T. Kraus, L. Malaquin, E. Delamarche, H. Schmid, N. D. Spencer and H. Wolf

      Article first published online: 5 SEP 2005 | DOI: 10.1002/adma.200501171

      Thumbnail image of graphical abstract

      Self-assembly, transfer, and integration of particles is achieved by combining self-assembly processes with an adhesion cascade (see Figure). This process complements and enhances existing fabrication methods as it allows the integration of particles into planar devices. Moreover, it is versatile in terms of particle size and materials, and can create arbitrary particle arrangements with functional particle–substrate connections.

    10. Thin Films of Block Copolymers as Planar Optical Waveguides (pages 2442–2446)

      D. H. Kim, K. H. A. Lau, J. W. F. Robertson, O.-J. Lee, U. Jeong, J. I. Lee, C. J. Hawker, T. P. Russell, J. K. Kim and W. Knoll

      Article first published online: 1 SEP 2005 | DOI: 10.1002/adma.200500170

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      Thin films of diblock copolymers with cylindrical microdomains oriented normal to the film plane are employed as planar optical waveguides in the Kretschmann configuration (see Figure). Their waveguiding properties were investigated by optical waveguide spectroscopy. The dielectric constants and the film thickness of the block copolymer layer can be independently obtained from fitting between the waveguide patterns for s- and p-polarization and Fresnel calculations.

    11. Self-Organization of FePt Nanoparticles on Photochemically Modified Diblock Copolymer Templates (pages 2446–2450)

      S. B. Darling, N. A. Yufa, A. L. Cisse, S. D. Bader and S. J. Sibener

      Article first published online: 22 AUG 2005 | DOI: 10.1002/adma.200500960

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      A cylindrical-phase diblock copolymer ultrathin film is modified with vacuum UV light to selectively remove one of the surface domain components. The corrugated film then serves as a template for the self-organization of colloidal magnetic nanoparticles (see Figure). This hierarchical methodology is a general route to the nanoscale assembly of functional materials. This work has ramifications for potential future bit-patterned magnetic-storage media.

    12. A Reagentless Biosensing Assembly Based on Quantum Dot–Donor Förster Resonance Energy Transfer (pages 2450–2455)

      I. L. Medintz, A. R. Clapp, J. S. Melinger, J. R. Deschamps and H. Mattoussi

      Article first published online: 13 SEP 2005 | DOI: 10.1002/adma.200500722

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      On the surface of a quantum dot (QD), maltose-binding protein (MBP, white and yellow in Figure) labeled with a cyanine dye (red) self-assembles, resulting in F?rster resonance energy transfer between the acceptor dye and the QD donor. Upon binding maltose, MBP undergoes a conformational change (white ⇌ yellow), causing concentration-dependent photoluminescence changes.

    13. Redox-Tunable Defects in Colloidal Photonic Crystals (pages 2455–2458)

      F. Fleischhaker, A. C. Arsenault, Z. Wang, V. Kitaev, F. C. Peiris, G. von Freymann, I. Manners, R. Zentel and G. A. Ozin

      Article first published online: 15 SEP 2005 | DOI: 10.1002/adma.200501055

      Thumbnail image of graphical abstract

      Reversible tuning of an intragap transmitting state induced by redox cycling is accomplished using a redox-active polyelectrolyte multilayer planar defect embedded in a colloidal photonic crystal (CPC). The wavelength position of the defect state can be changed by changing the oxidation state of the ferrocene moieties in the polymer backbone (see Figure). This could find applications in electrochemically tunable microcavities and CPC-based laser sources.

    14. Single-Walled Carbon Nanotube–CdS Nanocomposites as Light-Harvesting Assemblies: Photoinduced Charge-Transfer Interactions (pages 2458–2463)

      I. Robel, B. A. Bunker and P. V. Kamat

      Article first published online: 6 SEP 2005 | DOI: 10.1002/adma.200500418

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      Deposition of CdS nanoparticles on SWCNTs produces a photoactive composite that undergoes charge transfer interactions following excitation with visible light (see Figure). The transient bleaching recovery in approximately 200 ps confirms quick deactivation of excited CdS on the SWCNT surface. Visible excitation of the CdS–SWCNT film produces a photocurrent and thus provides evidence for the electron-transfer pathway in the composite.

    15. Electric-Field-Induced Rejection-Wavelength Tuning of Photonic-Bandgap Composites (pages 2463–2467)

      J. Xia, Y. Ying and S. H. Foulger

      Article first published online: 6 SEP 2005 | DOI: 10.1002/adma.200501166

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      Rejection-wavelength tuning is achieved by combining the mechanochromic response of photonic bandgap composites with the intrinsic electroactive properties of dielectric thin films. By straining the composite electrode, the photonic crystal interparticle lattice constant is varied in situ (see Figure). These simple-to-make films may find use in photonic devices that require a compact light-propagation controlling component.

    16. Single-Step Synthesis of a Highly Active Visible-Light Photocatalyst for Oxidation of a Common Indoor Air Pollutant: Acetaldehyde (pages 2467–2471)

      S. Rodrigues, K. T. Ranjit, S. Uma, I. N. Martyanov and K. J. Klabunde

      Article first published online: 30 AUG 2005 | DOI: 10.1002/adma.200402064

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      A Ti-Cr-MCM-48 photocatalyst prepared in a single step exhibits superior photocatalytic activity compared to TiO2-Cr-MCM-48 prepared by a post-impregnation method. The high activity of the photocatalyst is attributed to the synergistic interaction between the Cr ions dispersed in the silica framework and the nanocrystalline nature of titania crystallites anchored onto the pore walls (see Figure).

    17. Ultranarrow ZnSe Nanorods and Nanowires: Structure, Spectroscopy, and One-Dimensional Properties (pages 2471–2474)

      A. B. Panda, S. Acharya and S. Efrima

      Article first published online: 1 SEP 2005 | DOI: 10.1002/adma.200500551

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      Uniform ZnSe ultranarrow nanorods (1.3 nm × 4.5 nm) and 100–200 nm long nanowires with the same width have been produced and characterized, and the spectroscopic properties measured. The uniformity of the rods and wires is demonstrated in their spontaneous assembly into highly ordered 2D supercrystals (see Figure). Development of the rods from more spherical nuclei is demonstrated.

    18. Microwave-Induced-Plasma-Assisted Synthesis of Ternary Titanate and Niobate Phases (pages 2474–2477)

      D. J. Brooks, R. Brydson and R. E. Douthwaite

      Article first published online: 30 AUG 2005 | DOI: 10.1002/adma.200500736

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      Microwave-induced plasmas of argon (see Figure) and dioxygen have been used to rapidly prepare ternary niobate and titanate phases directly in the solid state from precursors that do not exhibit microwave heating at room temperature. However, for some reactions heating of the microwave-induced plasma can promote dielectric loss, which allows access to local temperatures greater than the equilibrium plasma temperature.

    19. Synthesis of Aligned Arrays of Ultrathin ZnO Nanotubes on a Si Wafer Coated with a Thin ZnO Film (pages 2477–2481)

      Y. Sun, G. M. Fuge, N. A. Fox, D. J. Riley and M. N. R. Ashfold

      Article first published online: 22 AUG 2005 | DOI: 10.1002/adma.200500726

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      Aligned arrays of ultrathin, high-quality ZnO nanotubes (see Figure) have been synthesized via hydrothermal growth methods on Si that has been pre-coated with a thin film of ZnO. The nanorods are single-crystalline, with typical wall thicknesses and outer diameters of 5–15 and 20–40 nm, respectively. Annealing the arrays in vacuum causes enhancement of UV photoluminescence.

    20. Two-Polymer Microtransfer Molding for Highly Layered Microstructures (pages 2481–2485)

      J.-H. Lee, C.-H. Kim, K.-M. Ho and K. Constant

      Article first published online: 1 SEP 2005 | DOI: 10.1002/adma.200500721

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      Two-polymer microtransfer molding (2P-μTM), an advanced microtransfer molding technique, is developed for fabrication of 3D microstructures. The use of two different photocurable prepolymers and a simple and robust filling and coating method allows an extremely high yield in layer-by-layer microfabrication able to produce highly layered microstructures with high structural fidelity (see Figure).

    21. Fabrication of PbS Nanoparticles in Polymer-Fiber Matrices by Electrospinning (pages 2485–2488)

      X. Lu, Y. Zhao and C. Wang

      Article first published online: 15 SEP 2005 | DOI: 10.1002/adma.200500196

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      PbS nanoparticles dispersed in polymer-fiber matrices by electrospinning are presented (see Figure). These PbS nanoparticles are roughly spherical in shape, each with a diameter of approximately 5 nm, and do not aggregate. This method will open up a wide route to functionalizing surfaces which can enable the fabrication of new types of optical, electric, and magnetic devices.

    22. Highly Efficient Visible-Blind Organic Ultraviolet Photodetectors (pages 2489–2493)

      H.-W. Lin, S.-Y. Ku, H.-C. Su, C.-W. Huang, Y.-T. Lin, K.-T. Wong and C.-C. Wu

      Article first published online: 13 SEP 2005 | DOI: 10.1002/adma.200401622

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      Highly efficient organic UV photodetectors that are not sensitive to visible radiation (“visible-blind”) but to UV-A radiation are fabricated using an organic donor–acceptor couple. High external quantum efficiencies (EQEs) comparable to commercial GaN devices, but covering the entire UV-A range (see Figure), make these devices promising for environmental and biomedical UV-sensing applications.

    23. Highly Efficient, Deep-Blue Doped Organic Light-Emitting Devices (pages 2493–2497)

      M.-T. Lee, C.-H. Liao, C.-H. Tsai and C. H. Chen

      Article first published online: 1 SEP 2005 | DOI: 10.1002/adma.200501169

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      All the attributes necessary for good OLED performance (see Figure), namely, high electroluminescence efficiency (5.4 cd A–1), long operational lifetime (10 000 h at an initial luminance of 100 cd m–2), and deep-blue color (color saturation: (0.14, 0.13)) are demonstrated by an OLED incorporating a novel, composite hole-transport layer and an emitter based on a new mono(styryl)amine dopant in the stable, anthracene-based blue host material, 2-methyl-9,10-di(2-naphthyl)anthracene.

    24. The Zwitterion Effect in Ionic Liquids: Towards Practical Rechargeable Lithium-Metal Batteries (pages 2497–2501)

      N. Byrne, P. C. Howlett, D. R. MacFarlane and M. Forsyth

      Article first published online: 7 SEP 2005 | DOI: 10.1002/adma.200500595

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      Practical lithium-metal batteries are the ultimate goal of battery researchers. The addition of a zwitterionic compound (see Figure) to an ionic liquid electrolyte doped with a lithium salt results in a 100% enhancement of the current densities achieved in the cycling of a lithium-metal cell. This phenomenon arises due to increased lithium-ion mobility or a reduced solid electrolyte interphase layer resistance.

    25. Fabrication and Structural Analysis of Binary Colloidal Crystals with Two-Dimensional Superlattices (pages 2501–2505)

      M. H. Kim, S. H. Im and O O. Park

      Article first published online: 6 SEP 2005 | DOI: 10.1002/adma.200501080

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      Binary colloidal crystals (see Figure) have been fabricated via the confined convective assembly method. By adjusting the ratio of the diameters of the small and large particles and the concentration of the small particles, various superlattices, including the previously reported LS2 and LS3 structures along with the new LS4 and LS5 structures, have been prepared.

    26. Synthesis of Well-Dispersed Y2O3:Eu Nanocrystals and Self-Assembled Nanodisks Using a Simple Non-hydrolytic Route (pages 2506–2509)

      H. Wang, M. Uehara, H. Nakamura, M. Miyazaki and H. Maeda

      Article first published online: 1 SEP 2005 | DOI: 10.1002/adma.200500503

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      Well-dispersed Y2O3:Eu nanocrystals, with a size less than 10 nm, and self-assembled nanodisks (see Figure) could be synthesized by a simple organometallic route. Two strong emission peaks located between 610 and 630 nm, and a 2.6 % quantum yield, are achievable upon excitation at 330 nm. Excellent dispersibility, a long lifetime, and improved emission may allow Y2O3:Eu nanocrystals to be useful for biological labeling.

    27. Non-aqueous Synthesis of Tin Oxide Nanocrystals and Their Assembly into Ordered Porous Mesostructures (pages 2509–2512)

      J. Ba, J. Polleux, M. Antonietti and M. Niederberger

      Article first published online: 13 SEP 2005 | DOI: 10.1002/adma.200501018

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      Highly ordered mesostructures of tin oxide have been obtained via the block-copolymer-assisted assembly of crystalline tin oxide nanoparticle sols. The 3.5 nm tin oxide nanoparticles obtained using low-temperature synthesis can be dispersed without the use of any stabilizers and are assembled via an evaporation-induced self-assembly (EISA) process (see Figure).

    28. Book Review: Physics of Solar Cells. By Peter Würfel. (page 2514)

      Ghassan E. Jabbour and Evan Williams

      Article first published online: 7 OCT 2005 | DOI: 10.1002/adma.200590102

    29. Author Index and Subject Index Adv. Mater. 20/2005 (pages 2515–2516)

      Article first published online: 7 OCT 2005 | DOI: 10.1002/adma.200590103

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