Advanced Materials

Cover image for Vol. 20 Issue 5

March, 2008

Volume 20, Issue 5

Pages 855–1078

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Correction
    6. Progress Report
    7. Review
    8. Communications
    9. Index
    1. Controlled Integration of Nanocrystals in Inverted Hexagonal Nano-Pits at the Surface of Light-Emitting Heterostructures (Adv. Mater. 5/2008)

      S. M. de Sousa Pereira, M. A. Martins, T. Trindade, I. M. Watson, D. Zhu and C. J. Humphreys

      Version of Record online: 29 FEB 2008 | DOI: 10.1002/adma.200890016

      Thumbnail image of graphical abstract

      Spontaneously formed nano-pits are exploited to effectively control the incorporation of gold nanocrystals (NCs) at the surface of light emitting InGaN/GaN heterostructures. Nano- engineering either the NCs size, or pit size, allows the number of NCs incorporated in each pit to be controlled, thus enabling research of well-defined assemblies of few gold NCs using an optically and electrically active substrate (see figure). The development of new nano-devices based on such hybrid nanostructures is briefly discussed.

  2. Inside Front Cover

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Correction
    6. Progress Report
    7. Review
    8. Communications
    9. Index
    1. Inside Front Cover: Mobility and Dynamics of Charge Carriers in Rubrene Single Crystals Studied by Flash-Photolysis Microwave Conductivity and Optical Spectroscopy (Adv. Mater. 5/2008)

      A. Saeki, S. Seki, T. Takenobu, Y. Iwasa and S. Tagawa

      Version of Record online: 29 FEB 2008 | DOI: 10.1002/adma.200890017

      Thumbnail image of graphical abstract

      The optoelectronic properties of single-crystal rubrene are investigated by microwave and optical spectroscopy, demonstrating the anisotropy, ambipolarity, and dynamics of the charge carriers. They are discussed in terms of charge recombination, exciton-exciton annihilation, quantum efficiency, triplet contribution, the extinction coefficient of radical cations/anions, and density functional theory.

  3. Contents

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Correction
    6. Progress Report
    7. Review
    8. Communications
    9. Index
    1. Contents: Adv. Mater. 5/2008 (pages 855–866)

      Version of Record online: 29 FEB 2008 | DOI: 10.1002/adma.200890014

  4. Correction

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Correction
    6. Progress Report
    7. Review
    8. Communications
    9. Index
    1. You have free access to this content
      Novel Complex Nanostructure from Directed Assembly of Block Copolymers on Incommensurate Surface Patterns (page 866)

      S. O. Kim, B. H. Kim, D. Meng, D. O. Shin, C. M. Koo, H. H. Solak and Q. Wang

      Version of Record online: 29 FEB 2008 | DOI: 10.1002/adma.200890015

      A novel complex nanostructure, produced by the directed assembly of a block copolymer thin film on chemically patterned surfaces, is presented. The new nanostructure, which consists of cylinders oriented alternately parallel and perpendicular to the surface (see figure, a result of self-consistent field calculations), demonstrates that a judiciously designed chemical pattern may be used to fabricate a well-ordered complex nanostructure in block copolymer thin films.

      This article corrects:
  5. Progress Report

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Correction
    6. Progress Report
    7. Review
    8. Communications
    9. Index
    1. Nanobiomaterials and Nanoanalysis: Opportunities for Improving the Science to Benefit Biomedical Technologies (pages 867–877)

      D. W. Grainger and D. G. Castner

      Version of Record online: 8 FEB 2008 | DOI: 10.1002/adma.200701760

      Thumbnail image of graphical abstract

      Nanomaterials often present enormous surface areas in contact with physiological or biological fluids in biomedical applications in vitro and in vivo. Typically advocated for performance enhancements in biotechnology, these surfaces are reactive, adsorptive and desorptive, resulting in stability, and toxicity issues. Rigorous surface analysis for these materials, including development of appropriate assays in relevant biological milieu, should be required for applications in vitro and in vivo.

  6. Review

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Correction
    6. Progress Report
    7. Review
    8. Communications
    9. Index
    1. Thermodynamics and Kinetic Processes of Polymer Blends and Block Copolymers in the Presence of Pressurized Carbon Dioxide (pages 879–898)

      T. A. Walker, D. J. Frankowski and R. J. Spontak

      Version of Record online: 29 FEB 2008 | DOI: 10.1002/adma.200700076

      Thumbnail image of graphical abstract

      The effects of high-pressure CO2 on the thermodynamics and kinetics of multicomponent polymer systems are reviewed (see figure for examples), with emphasis on commercial polymer processes that could benefit from this materials processing strategy. The modification of multicomponent polymer systems by high-pressure CO2 constitutes an environmentally benign, inexpensive, and versatile route to new materials with designer properties and phase behavior.

  7. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Correction
    6. Progress Report
    7. Review
    8. Communications
    9. Index
    1. DNA Block Copolymer Micelles – A Combinatorial Tool for Cancer Nanotechnology (pages 899–902)

      F. E. Alemdaroglu, N. C. Alemdaroglu, P. Langguth and A. Herrmann

      Version of Record online: 30 JAN 2008 | DOI: 10.1002/adma.200700866

      Thumbnail image of graphical abstract

      A novel micelle platform consisting of amphiphilic DNA block copolymers is introduced for chemotherapeutic drug delivery, allowing combinatorial testing of the drug carrier system. Oligodeoxynucleotide modified targeting units are “clicked” into the micelle corona by hybridization, allowing perfect control of surface functionalities of the nanoparticle system. Cancer cells are efficiently killed when targeting units and chemotherapeutic act together within the DNA block copolymer aggregates.

    2. Rare-Earth-Doped Nanocrystalline Titania Microspheres Emitting Luminescence via Energy Transfer (pages 903–908)

      L. Li, C.-K. Tsung, Z. Yang, G. D. Stucky, L. D. Sun, J. F. Wang and C. H. Yan

      Version of Record online: 30 JAN 2008 | DOI: 10.1002/adma.200701507

      Thumbnail image of graphical abstract

      Rare-earth-doped nanocrystalline titania microspheres are prepared using an inexpensive and scalable ultrasonic spray pyrolysis method. Anatase titania nanocrystals distributed inside these microspheres function as sensitizers to absorb light and transfer energy to rare earth ions, which leads to intense and narrow bandwidth emission.

    3. Epitaxial Transition Metal Oxide Nanostructures Fabricated by a Combination of AFM Lithography and Molybdenum Lift-Off (pages 909–913)

      N. Suzuki, H. Tanaka and T. Kawai

      Version of Record online: 30 JAN 2008 | DOI: 10.1002/adma.200700646

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      A novel process for the microfabrication of metal oxide nanostructures is developed based on combining thin film deposition at high temperatures with the use of a Mo mask fabricated by atomic force microscopy lithography. The Mo mask is lifted-off using H2O2 solution after deposition of the oxide film. The figure shows nanoscale Fe2.5Mn0.5O4 stripes fabricated by this process.

    4. Multicolor Polymer Nanocomposites: In Situ Synthesis and Fabrication of 3D Microstructures (pages 914–919)

      Z.-B. Sun, X.-Z. Dong, W.-Q. Chen, S. Nakanishi, X.-M. Duan and S. Kawata

      Version of Record online: 30 JAN 2008 | DOI: 10.1002/adma.200702035

      Thumbnail image of graphical abstract

      The multiphoton polymerization of CdS–polymer nanocomposites is used to fabricate 3D luminescent structures such as the multicolor “microbull” shown in the figure. The CdS nanoparticles are synthesized in situ within the polymer matrices with their size controlled by the amount of added crosslinker.

    5. Mobility and Dynamics of Charge Carriers in Rubrene Single Crystals Studied by Flash-Photolysis Microwave Conductivity and Optical Spectroscopy (pages 920–923)

      A. Saeki, S. Seki, T. Takenobu, Y. Iwasa and S. Tagawa

      Version of Record online: 30 JAN 2008 | DOI: 10.1002/adma.200702463

      Thumbnail image of graphical abstract

      The optoelectronic properties of single-crystal rubrene are investigated by microwave and optical spectroscopy, demonstrating the anisotropy, ambipolarity, and dynamics of the charge carriers. They are discussed in terms of charge recombination, exciton-exciton annihilation, quantum efficiency, triplet contribution, the extinction coefficient of radical cations/anions, and density functional theory.

    6. Write Current Reduction in Transition Metal Oxide Based Resistance Change Memory (pages 924–928)

      S.-E. Ahn, M.-J. Lee, Y. Park, B. S. Kang, C. B. Lee, K. H. Kim, S. Seo, D.-S. Suh, D.-C. Kim, J. Hur, W. Xianyu, G. Stefanovich, H. Yin, I.-K. Yoo, J.-H. Lee, J.-B. Park, I.-G. Baek and B. H. Park

      Version of Record online: 5 FEB 2008 | DOI: 10.1002/adma.200702081

      Thumbnail image of graphical abstract

      A novel memory cell structure with a Pt/Ti-doped NiO/Pt architecture is shown to exhibit the lowest write current reported thus far for a unipolar switching resistance-change-based device, as shown in the figure. The write current decreases dramatically upon scaling to cell sizes smaller than 100 nm×100 nm. High-density universal memory can be fabricated by combining this node element with a selective switch.

    7. A Simple and Efficient Route to Transparent Nanocomposites (pages 929–932)

      S. H. Stelzig, M. Klapper and K. Müllen

      Version of Record online: 5 FEB 2008 | DOI: 10.1002/adma.200701608

      Thumbnail image of graphical abstract

      The use of multicomponent solvent systems and multiply functionalized emulsifiers opens a versatile avenue to high-quality nanocomposites. Quantitative transfer of inorganic particles from an aqueous dispersion directly to hydrophobic solvent, where aggregation of the particles is fully suppressed, can be achieved on a large scale. Due to additional functionality on the surfaces, the particles can interact with a polymer matrix, allowing formation of homogeneous organic–inorganic hybrid materials.

    8. Minimally Invasive Protein Delivery with Rapidly Dissolving Polymer Microneedles (pages 933–938)

      S. P. Sullivan, N. Murthy and M. R. Prausnitz

      Version of Record online: 5 FEB 2008 | DOI: 10.1002/adma.200701205

      Thumbnail image of graphical abstract

      A new room-temperature, in situ polymerization process to produce microneedles (see figure), which can encapsulate functional biomolecules and dissolve within minutes, is presented. The dissolution rate and mechanical strength of these polymer microneedles can be tailored by changing monomer composition and microneedle geometry. Drug delivery using micrometer-scale needles that dissolve in the skin could eliminate the pain and dangers of hypodermic needle use.

    9. Light-Induced Charge Transfer in Pyrene/CdSe-SWNT Hybrids (pages 939–946)

      L. Hu, Y.-L. Zhao, K. Ryu, C. Zhou, J. F. Stoddart and G. Grüner

      Version of Record online: 5 FEB 2008 | DOI: 10.1002/adma.200701125

      Thumbnail image of graphical abstract

      Hybrids of pyrene/CdSe-single-walled carbon nanotubes (SWNTs) are fabricated by self-assembling surface-functionalized pyrene/CdSe nanoparticles onto CVD-grown SWNTs. Light- induced charge transfer from the nanoparticles to the nanotubes is determined from the threshold voltage shift of a SWNT field-effect transistor, yielding a maximum value of 2.2 electrons per pyrene/CdSe nanoparticle.

    10. Room-Temperature Growth of Uniform Tellurium Nanorods and the Assembly of Tellurium or Fe3O4 Nanoparticles on the Nanorods (pages 947–952)

      J. Yuan, H. Schmalz, Y. Xu, N. Miyajima, M. Drechsler, M. W. Möller, F. Schacher and A. H. E. Müller

      Version of Record online: 8 FEB 2008 | DOI: 10.1002/adma.200701756

      Thumbnail image of graphical abstract

      Uniform and single-crystalline tellurium (Te) nanorods with high aspect ratio (≈20) are prepared via a cylindrical polymer brush-assisted method in THF at room temperature. These rods are well dispersed and stable in solution. Te nanorods prepared by this method are successfully used as template to assemble inorganic (Te or Fe3O4) nanoparticles on the nanorod surface to form a Te nanorod / Te or Fe3O4 nanoparticle complex structure (see figure).

    11. Structural Phase Coexistence under Reversible Thermal Control (pages 953–958)

      C.-M. Cheng and P. R. LeDuc

      Version of Record online: 8 FEB 2008 | DOI: 10.1002/adma.200701595

      Thumbnail image of graphical abstract

      Phase transition and coexistence are observed to define behaviors and enable advances in a variety of areas. We show that alterations in the cell structure for actin cytoskeleton produces distinct phases based on changes in the thermal environment. These studies suggest that the entire cell as well as subcellular regions may have distinct phases or patterns that retain a reversible equilibrium directly related to the thermal environment.

    12. Growth-Mode-Induced Narrowing of Optical Spectra of an Organic Adlayer (pages 959–963)

      T. Dienel, C. Loppacher, S. C. B. Mannsfeld, R. Forker and T. Fritz

      Version of Record online: 8 FEB 2008 | DOI: 10.1002/adma.200701684

      Thumbnail image of graphical abstract

      Sharpening of optical spectra caused by commensurate growth of an organic adlayer on salt single crystals is reported. The structure is elucidated by atomic force microscopy and advanced potential energy calculations. Continued deposition or annealing induces a rearrangement of the molecular monolayer into 3D crystallites, demonstrating the crucial role of the Coulomb interaction with the substrate to form the unexpected commensurate structure.

    13. Enhancing the Performance of Polymer Light-Emitting Diodes by Integrating Self-Assembled Organic Nanowires (pages 964–969)

      Q. Niu, Y. Zhou, L. Wang, J. Peng, J. Wang, J. Pei and Y. Cao

      Version of Record online: 8 FEB 2008 | DOI: 10.1002/adma.200702591

      Thumbnail image of graphical abstract

      The in situ assembly of organic nanowires within a conjugated polymer matrix yields blended emitting layers that are used in polymer light-emitting diodes (PLEDs). These PLEDs show significant enhancements in luminous efficiency and external quantum efficiency. The figure shows the structures of the materials used in the devices and the morphology of the organic nanowires.

    14. Stable Bionic Superhydrophobic Coating Surface Fabricated by a Conventional Curing Process (pages 970–974)

      Z. Z. Luo, Z. Z. Zhang, L. T. Hu, W. M. Liu, Z. G. Guo, H. J. Zhang and W. J. Wang

      Version of Record online: 8 FEB 2008 | DOI: 10.1002/adma.200701229

      Thumbnail image of graphical abstract

      A bionic superhydrophobic surface with both micrometer and nanometer structure roughness is achieved by a simple and conventional coating–curing process on engineering materials such as stainless steel. The superhydrophobic surfaces (water contact angle of about 165°, see figure) possess very good cohesional strength and high- and low-temperature resistance, which is very important for practical industrial applications of these coatings.

    15. Charge Trapping at the Dielectric of Organic Transistors Visualized in Real Time and Space (pages 975–979)

      S. G. J. Mathijssen, M. Kemerink, A. Sharma, M. Cölle, P. A. Bobbert, R. A. J. Janssen and D. M. de Leeuw

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adma.200702688

      Thumbnail image of graphical abstract

      Scanning Kelvin probe microscopy demonstrates that water-induced charge trapping at the SiO2 dielectric – visualized in real time and space – is responsible for the commonly observed gate-bias-induced threshold-voltage shift in organic field-effect transistors. When a bias is applied to the electrodes, charges are injected onto the SiO2 (see background of the figure). When the contacts are grounded, the charges are released again (foreground picture).

    16. Electric-Field-Assisted Growth of Highly Uniform and Oriented Gold Nanotriangles on Conducting Glass Substrates (pages 980–983)

      P. R. Sajanlal and T. Pradeep

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adma.200701790

      Thumbnail image of graphical abstract

      A method for the growth of highly aligned gold nanotriangles (NTs) on conducting glass surfaces is described. This may be described as ‘potential-assisted seed mediated growth'. Atomic force microscopy confirms that all the triangles observed are equilateral and are uniformly stacked. The NT-coated glass exhibits intense near-infrared absorption and strong surface-enhanced Raman activity.

    17. Macroporous Lanthanide-Organic Coordination Polymer Foams and Their Corresponding Lanthanide Oxides (pages 984–988)

      Z. Shen, G. Zhang, H. Zhou, P. Sun, B. Li, D. Ding and T. Chen

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adma.200702249

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      Macroporous lanthanide-organic coordination polymer foams (macroscopic monoliths) with aligned or hierarchical macropores are fabricated for the first time by a template-free hydrothermal method. Hierarchically meso-macroporous or macroporous monolithic foams of lanthanide oxides or lanthanide-transition metal oxides can be obtained after calcination of the coordination polymer foams.

    18. Self-Assembly of Cell–Microparticle Hybrids (pages 989–993)

      Y. Krishnamachari, M. E. Pearce and A. K. Salem

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adma.200701689

      Thumbnail image of graphical abstract

      Synthetic-biological hybrids of biodegradable microparticles and transfected cells are assembled, as schematically illustrated in the figure. The cells are surface-functionalized with biotin and the particle surface is also engineered with biotin. Avidin is then used as a bridging protein to bind together the microparticles and the surface- functionalized cells.

    19. Direct Gas-Phase Synthesis of Heterostructured Nanoparticles through Phase Separation and Surface Segregation (pages 994–999)

      Y.-H. Xu and J.-P. Wang

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adma.200602895

      Thumbnail image of graphical abstract

      A general gas-phase synthesis approach is developed to fabricate heterostructured nanoparticles with well-defined surfaces and interfaces. The figure shows examples of various nanoparticle morphologies that can be obtained by tuning the phase separation and segregation processes, thereby leading to directional diffusion and well-defined interfaces at the single-particle level.

    20. Trapping Metallic Liquid Mercury in a Carbon Shell by the Decomposition of Dimethyl Mercury (pages 1000–1002)

      A. Gedanken, E. Luvchik, J. M. Calderon-Moreno, N. Veglio and J. L. I. Tamarit

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adma.200701980

      Thumbnail image of graphical abstract

      An efficient single-step synthesis of mercury droplets covered with a carbon shell by the thermolysis of dimethyl mercury under its autogenic pressure is described. This is a unique case in which a liquid metal is trapped inside a nano- and micrometer size carbon capsule. The air-stability and the characterization by XRD, TEM, DSC, HRSEM, and HRTEM of this composite are reported.

    21. CH-π Interactions as the Driving Force for Silicone-Based Nanocomposites with Exceptional Properties (pages 1003–1007)

      A. Beigbeder, M. Linares, M. Devalckenaere, P. Degée, M. Claes, D. Beljonne, R. Lazzaroni and P. Dubois

      Version of Record online: 12 FEB 2008 | DOI: 10.1002/adma.200701497

      Thumbnail image of graphical abstract

      The preparation and the characterization of nanotubes-reinforced poly(dimethyl)siloxane nanocomposites is reported. Surprisingly the use of “self pure” multiwall carbon nanotubes, that is, without any surface functionalization or specific surface treatment, turns out to be the most efficient approach to impart new key-properties to the silicone matrix.

    22. A Solution Chemistry Approach for the Selective Formation of Ultralong Nanowire Bundles of Crystalline Cd(OH)2 on Substrates (pages 1008–1012)

      V. R. Shinde, H.-S. Shim, T. P. Gujar, H. J. Kim and W. B. Kim

      Version of Record online: 30 JAN 2008 | DOI: 10.1002/adma.200701828

      Thumbnail image of graphical abstract

      The controlled precipitation of a supersaturated Cd2+ solution is used to selectively deposit Cd(OH)2 nanowire bundles on a substrate. As schematically depicted in the figure, when the Cd2+ ionic product exceeds the solubility product, heterogeneous and homogeneous nucleation occur independently on the substrate and in the solution to give nanowire bundles and hexagonal plates, respectively.

    23. A Switchable NLO Organic-Inorganic Compound Based on Conformationally Chiral Disulfide Molecules and Bi(III)I5 Iodobismuthate Networks (pages 1013–1017)

      W. Bi, N. Louvain, N. Mercier, J. Luc, I. Rau, F. Kajzar and B. Sahraoui

      Version of Record online: 5 FEB 2008 | DOI: 10.1002/adma.200701753

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      A novel organic-inorganic hybrid based on cystamine and BiI5chains is prepared. Due to the flexibility of the disulfide molecules in the structure, single crystals or crystalline thin films of this hybrid undergo a reversible acentric-to-centric structural transition at moderate conditions (T = 36.8 °C). This makes the title compound an excellent candidate for temperature controlled SHG or THG switches.

    24. Mobile Ionic Impurities in Poly(vinyl alcohol) Gate Dielectric: Possible Source of the Hysteresis in Organic Field-Effect Transistors (pages 1018–1022)

      M. Egginger, M. Irimia-Vladu, R. Schwödiauer, A. Tanda, I. Frischauf, S. Bauer and N. S. Sariciftci

      Version of Record online: 5 FEB 2008 | DOI: 10.1002/adma.200701479

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      Ionic impurities in gate dielectrics are outlined as a possible source for threshold voltage shifts in organic field effect transistors. Using poly(vinyl alcohol) containing sodium acetate impurities we show how transistors can be designed for memory elements or polymer integrated circuits.

    25. Pentacene-Zinc Oxide Vertical Diode with Compatible Grains and 15-MHz Rectification (pages 1023–1028)

      B. N. Pal, J. Sun, B. J. Jung, E. Choi, A. G. Andreou and H. E. Katz

      Version of Record online: 5 FEB 2008 | DOI: 10.1002/adma.200701550

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      Vertical p-n junction organic-inorganic hybrid diodes are fabricated and characterized. The current density and rectification speed in the open atmosphere are higher than previously reported organic vertical diodes with relatively lower operating voltage, and the stability is encouraging.

    26. Positive Temperature Coefficient of Resistivity in Donor-Doped BaTiO3 Ceramics derived from Nanocrystals synthesized at Low Temperature (pages 1029–1033)

      R. L. Brutchey, G. Cheng, Q. Gu and D. E. Morse

      Version of Record online: 5 FEB 2008 | DOI: 10.1002/adma.200701804

      Thumbnail image of graphical abstract

      Small, donor-doped Ba1-xLaxTiO3nanocrystals are successfully prepared for the first time. These nanocrystals are suitable precursors for small-grain Ba1-xLaxTiO3 ceramics with a sizeable positive temperature coefficient of resistivity (PTCR) that is comparable to that of traditional large-grain ceramics derived from solid-state routes.

    27. Structural Control of Surfactant-Templated Mesoporous Silica Formed Inside Columnar Alumina Pores (pages 1034–1037)

      A. Yamaguchi, H. Kaneda, W. Fu and N. Teramae

      Version of Record online: 8 FEB 2008 | DOI: 10.1002/adma.200701368

      Thumbnail image of graphical abstract

      A hybrid mesoporous membrane is developed by forming surfactant-templated mesoporous silica inside columnar alumina pores of an alumina membrane. Predominant formation of one-dimensional silica nanochannels (channel diameter = 8 nm) is achieved by controlling the aging time and temperature for preparation of the precursor solution using Pluronic P123 as a template surfactant.

    28. Controlled Integration of Nanocrystals in Inverted Hexagonal Nano-Pits at the Surface of Light-Emitting Heterostructures (pages 1038–1043)

      S. M. de Sousa Pereira, M. A. Martins, T. Trindade, I. M. Watson, D. Zhu and C. J. Humphreys

      Version of Record online: 8 FEB 2008 | DOI: 10.1002/adma.200701739

      Thumbnail image of graphical abstract

      Spontaneously formed nano-pits are exploited to effectively control the incorporation of gold nanocrystals (NCs) at the surface of light emitting InGaN/GaN heterostructures. Nano- engineering either the NCs size, or pit size, allows the number of NCs incorporated in each pit to be controlled, thus enabling research of well-defined assemblies of few gold NCs using an optically and electrically active substrate (see figure). The development of new nano-devices based on such hybrid nanostructures is briefly discussed.

    29. Self-Organized TiO2 Nanotube Array Sensor for the Determination of Chemical Oxygen Demand (pages 1044–1049)

      Q. Zheng, B. Zhou, J. Bai, L. Li, Z. Jin, J. Zhang, J. Li, Y. Liu, W. Cai and X. Zhu

      Version of Record online: 8 FEB 2008 | DOI: 10.1002/adma.200701619

      Thumbnail image of graphical abstract

      Highly organized arrays of TiO2nanotubes (as depicted in the figure) are integrated into a thin-cell photoelectrocatalytic reactor for the rapid determination of chemical oxygen demand in wastewater samples. The high photocatalytic activity of the nanotubes arises from the efficient separation of photogenerated electrons and holes, and enables the fabrication of sensors exhibiting good accuracy, stability, and reproducibility.

    30. Non-Aqueous Sol–Gel Approach towards the Controllable Synthesis of Nickel Nanospheres, Nanowires, and Nanoflowers (pages 1050–1054)

      F. L. Jia, L. Z. Zhang, X. Y. Shang and Y. Yang

      Version of Record online: 8 FEB 2008 | DOI: 10.1002/adma.200702159

      Thumbnail image of graphical abstract

      Nickel nanospheres, nanowires, and nanoflowers are synthesized via a facile non-aqueous sol–gel route involving the reaction of nickel acetylacetonate with benzyl alcohol at 200 °C in the presence of varying magnetic fields, as illustrated in the figure. Benzyl alcohol acts as both the solvent and reductant in this system. The nanostructures show substantial enhancement in coercivity as compared to bulk nickel.

    31. Formation of Nb2O5 Nanotube Arrays Through Phase Transformation** (pages 1055–1058)

      C. Yan and D. Xue

      Version of Record online: 8 FEB 2008 | DOI: 10.1002/adma.200701752

      Thumbnail image of graphical abstract

      The successful synthesis of monoclinic Nb2O5nanotube arrays (see figure) from pseudo-hexagonal Nb2O5 nanorod arrays is reported; the synthesis is based on phase transformation accompanied by void formation, where voids can be intriguingly generated during phase transformation. A key parameter for achieving nanotube growth is the energy difference between the pseudo-hexagonal and monoclinic Nb2O5 nanostructures, which determines the phase transformation.

    32. Hollow TiO2 Hemispheres Obtained by Colloidal Templating for Application in Dye-Sensitized Solar Cells (pages 1059–1064)

      S.-C. Yang, D.-J. Yang, J. Kim, J.-M. Hong, H.-G. Kim, I.-D. Kim and H. Lee

      Version of Record online: 8 FEB 2008 | DOI: 10.1002/adma.200701808

      Thumbnail image of graphical abstract

      Hollow TiO2hemispheres for application in dye-sensitized solar cells are prepared by means of rf-sputtering onto colloidal templated substrates. After removing the organic templates by thermal decomposition, quasi-ordered networks of hollow TiO2 hemispheres were formed. This approach should open up new opportunities for processing material architectures with high surface activity and effective charge transport for high performance photovoltaic and photoelectrochemical cells.

    33. Control of Electric Field Strength and Orientation at the Donor–Acceptor Interface in Organic Solar Cells (pages 1065–1070)

      A. Liu, S. Zhao, S.-B. Rim, J. Wu, M. Könemann, P. Erk and P. Peumans

      Version of Record online: 29 FEB 2008 | DOI: 10.1002/adma.200702554

      Thumbnail image of graphical abstract

      Electrical doping is essential to achieve efficient photocurrent extraction in small-molecular-weight organic solar cells. It is shown that such doping creates strong electric fields at the donor-acceptor interface that prevent geminate electron–hole recombination.

    34. Thin-Walled Carbon Nanocages: Direct Growth, Characterization, and Applications (pages 1071–1075)

      Z. M. Sheng and J. N. Wang

      Version of Record online: 29 FEB 2008 | DOI: 10.1002/adma.200701815

      Thumbnail image of graphical abstract

      Carbon nanocages with one or a few graphitic layers (see figure) are directly grown in the solid state by heat treatment of a carbon–iron mixture at low temperature. Such thin-walled nanocages have a fine size of 3–12 nm and a high surface area of 535 m2 g–1. They are are a superb catalyst support for low-temperature fuel cells and could be applicable in many other fields.

  8. Index

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Correction
    6. Progress Report
    7. Review
    8. Communications
    9. Index

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