Advanced Functional Materials

Cover image for Vol. 16 Issue 4

March, 2006

Volume 16, Issue 4

Pages 451–584

    1. Cover Picture: Composite Silica Spheres with Magnetic and Luminescent Functionalities (Adv. Funct. Mater. 4/2006)

      V. Salgueiriño-Maceira, M. A. Correa-Duarte, M. Spasova, L. M. Liz-Marzán and M. Farle

      Version of Record online: 22 FEB 2006 | DOI: 10.1002/adfm.200690014

      Water-based luminescent magnetic colloidal particles have been prepared by the encapsulation of iron oxide nanoparticles and luminescent semiconductor nanocrystals in silica spheres. These patterned magnetic silica spheres are expected to serve as luminescent markers while attached to bioligands, and are capable of being driven by a magnetic field (see Figure and cover).

    2. Inside Front Cover: Perfect Bi4Ti3O12 Single-Crystal Films via Flux-Mediated Epitaxy (Adv. Funct. Mater. 4/2006)

      R. Takahashi, Y. Yonezawa, M. Ohtani, M. Kawasaki, K. Nakajima, T. Chikyow, H. Koinuma and Y. Matsumoto

      Version of Record online: 22 FEB 2006 | DOI: 10.1002/adfm.200690015

      Flux-mediated epitaxy is used to prepare single-crystal films of ferroelectric Bi4Ti3O12 (see Figure and inside cover). Combinatorial methods are used to determine the best flux (CuO) that allows high-quality films to be prepared, in spite of the presence of volatile Bi. The quality of the film is evident in the crystals' grain size, electric properties, and atomically flat surface.

    3. Hybrid Molecular/Inorganic Semiconductor Transistors in Vertical Architectures (pages 459–467)

      M. S. Meruvia and I. A. Hümmelgen

      Version of Record online: 3 JAN 2006 | DOI: 10.1002/adfm.200500302

      Thumbnail image of graphical abstract

      Hybrid organic/inorganic semiconductor–metal–semiconductor transistors show high gain (see Figure) and can be produced using simple technologies, maintaining compatibility with the well-established silicon electronics technology. These devices open new attractive possibilities due to the huge variety of molecular semiconductors.

    4. Local Probing of Photocurrent and Photoluminescence in a Phase-Separated Conjugated-Polymer Blend by Means of Near-Field Excitation (pages 469–476)

      R. Riehn, R. Stevenson, D. Richards, D.-J. Kang, M. Blamire, A. Downes and F. Cacialli

      Version of Record online: 3 JAN 2006 | DOI: 10.1002/adfm.200400528

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      Polymer blends for photovoltaic devices are characterized using scanning near-field microscopy. Fluorescence and photoconductivity imaging are combined (see Figure) to elucidate spatial distribution and relative efficiency of current generation and photoluminescence in different domains of polyfluorene-based, compositionally heterogeneous films. The energy adsorbed by the polymer film in the different regions is estimated with the help of the Bethe–Bouwkamp model.

    5. Synthesis, Liquid-Crystalline Properties, and Photo-optical Studies of Photoresponsive Oligomeric Mesogens as Dopants in a Chiral Glassy Liquid Crystal (pages 477–484)

      H. Akiyama, V. A. Mallia and N. Tamaoki

      Version of Record online: 10 JAN 2006 | DOI: 10.1002/adfm.200500176

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      Photoresponsive oligomeric mesogens (Figure, top), when used as dopants in a chiral glassy liquid crystal, induce a large and tunable shift in the wavelength of the reflection band. The reflectivity of these materials could be tuned over the entire visible region using light, and thus they provide a thermally stable full-color image, as shown in the bottom part of the Figure.

    6. Perfect Bi4Ti3O12 Single-Crystal Films via Flux-Mediated Epitaxy (pages 485–491)

      R. Takahashi, Y. Yonezawa, M. Ohtani, M. Kawasaki, K. Nakajima, T. Chikyow, H. Koinuma and Y. Matsumoto

      Version of Record online: 19 JAN 2006 | DOI: 10.1002/adfm.200500390

      Thumbnail image of graphical abstract

      Flux-mediated epitaxy is used to prepare single-crystal films of ferroelectric Bi4Ti3O12 (see Figure and inside cover). Combinatorial methods are used to determine the best flux (CuO) that allows high-quality films to be prepared, in spite of the presence of volatile Bi. The quality of the film is evident in the crystals' grain size, electric properties, and atomically flat surface.

    7. Harnessing the Actuation Potential of Solid-State Intercalation Compounds (pages 492–498)

      Y. Koyama, T. E. Chin, U. Rhyner, R. K. Holman, S. R. Hall and Y.-M. Chiang

      Version of Record online: 10 JAN 2006 | DOI: 10.1002/adfm.200500633

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      Electrochemical intercalation of high-elastic-modulus inorganic compounds (see Figure) provides a low-voltage mechanism (<5V) with intrinsic energy density approaching that of hydraulics, and more than a hundred times that of existing field-operated mechanisms such as piezostriction and magnetostriction.

    8. Intermolecular Forces in the Self-Assembly of Peptide Amphiphile Nanofibers (pages 499–508)

      J. C. Stendahl, M. S. Rao, M. O. Guler and S. I. Stupp

      Version of Record online: 19 JAN 2006 | DOI: 10.1002/adfm.200500161

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      Peptide amphiphile (PA) molecules self-assemble from aqueous media into three-dimensional networks of bioactive nanofibers (see Figure). Multiple non-covalent interactions promote assembly of the supramolecular nanofibers and ultimately determine the bulk physical properties of the macroscopic gels. Spectroscopic techniques and oscillatory rheology are used to better understand the assembly mechanism of a typical PA molecule known as PA-1.

    9. Composite Silica Spheres with Magnetic and Luminescent Functionalities (pages 509–514)

      V. Salgueiriño-Maceira, M. A. Correa-Duarte, M. Spasova, L. M. Liz-Marzán and M. Farle

      Version of Record online: 24 JAN 2006 | DOI: 10.1002/adfm.200500565

      Thumbnail image of graphical abstract

      Water-based luminescent magnetic colloidal particles have been prepared by the encapsulation of iron oxide nanoparticles and luminescent semiconductor nanocrystals in silica spheres. These patterned magnetic silica spheres are expected to serve as luminescent markers while attached to bioligands, and are capable of being driven by a magnetic field (see Figure and cover).

      Corrected by:

      Correction: Composite Silica Spheres with Magnetic and Luminescent Functionalities

      Vol. 16, Issue 10, 1266, Version of Record online: 26 JUN 2006

    10. Enhancement of External Quantum Efficiency of Red Phosphorescent Organic Light-Emitting Devices with Facially Encumbered and Bulky PtII Porphyrin Complexes (pages 515–519)

      M. Ikai, F. Ishikawa, N. Aratani, A. Osuka, S. Kawabata, T. Kajioka, H. Takeuchi, H. Fujikawa and Y. Taga

      Version of Record online: 3 JAN 2006 | DOI: 10.1002/adfm.200500492

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      Facially encumbered and bulky meso-aryl substituted PtIIporphyrins (see Figure) improve the external quantum efficiency of red phosphorescent organic light-emitting devices. “Double decamethylene straps” between the meso-substituted aryl groups impose a more effective facial encumbrance, and severely restrict the rotational freedom of the meso-aryl groups.

    11. Hydrogen Adsorption in Metal–Organic Frameworks: Cu-MOFs and Zn-MOFs Compared (pages 520–524)

      B. Panella, M. Hirscher, H. Pütter and U. Müller

      Version of Record online: 19 JAN 2006 | DOI: 10.1002/adfm.200500561

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      Physisorption of hydrogen in microporous materials with high specific surface area (SSA) is a promising route to achieve high hydrogen-storage capacities. The hydrogen uptake of two metal–organic framework (MOF) structures based on Zn (MOF-5) and Cu (Cu-BTC) metal ions are examined. The saturation values at 77 K are 5.1 and 3.6 wt.-%, respectively, and proportional to the SSA. At low pressures, however, Cu-BTC shows a higher hydrogen uptake than MOF-5.

    12. Extremely High Silver Ionic Conductivity in Composites of Silver Halide (AgBr, AgI) and Mesoporous Alumina (pages 525–530)

      H. Yamada, A. J. Bhattacharyya and J. Maier

      Version of Record online: 21 DEC 2005 | DOI: 10.1002/adfm.200500538

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      Silver ionic conductivity in heterogeneous systems of AgX:Al2O3 (X = Br,I) is highly enhanced by employing mesoporous Al2O3 particles (see Figure). Conductivity enhancements of more than 103 have been obtained, and these enhancements are explained satisfactorily by the concept of heterogeneous doping, with additional contributions from stacking disorder in the case of AgI:Al2O3 composites.

    13. Magnetic Properties of Quinoidal Oligothiophenes: More Than Good Candidates for Ambipolar Organic Semiconductors? (pages 531–536)

      R. Ponce Ortiz, J. Casado, V. Hernández, J. T. López Navarrete, E. Ortí, P. M. Viruela, B. Milián, S. Hotta, G. Zotti, S. Zecchin and B. Vercelli

      Version of Record online: 19 JAN 2006 | DOI: 10.1002/adfm.200500404

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      Neutral quinoidal oligothiophenes can exist in a magnetic active biradical state. Spectroscopic and quantum chemical data show a thermally activated interconversion between quinoid diamagnetic forms and aromatic paramagnetic biradical species (see Figure).

    14. Sharp Infrared Emission from Single-Crystalline Indium Nitride Nanobelts Prepared Using Guided-Stream Thermal Chemical Vapor Deposition (pages 537–541)

      M. S. Hu, W. M. Wang, T. T. Chen, L. S. Hong, C. W. Chen, C. C. Chen, Y. F. Chen, K. H. Chen and L. C. Chen

      Version of Record online: 8 DEC 2005 | DOI: 10.1002/adfm.200500553

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      InN nanobelts 20–200 nm wide and several tens of micrometers long (see Figure) are prepared using a new chemical vapor deposition technique. The nanobelts are single-crystalline, have a wurtzite structure, and exhibit a rectangular cross section with self-selective facets. Photoluminescence spectra reveal an IR emission peak at 0.76 eV with a full width at half maximum of 14 meV, narrower than the values reported for InN epilayers.

    15. Covalent Layer-by-Layer Assembly of Conjugated Polymers and CdSe Nanoparticles: Multilayer Structure and Photovoltaic Properties (pages 542–548)

      Z. Liang, K. L. Dzienis, J. Xu and Q. Wang

      Version of Record online: 22 DEC 2005 | DOI: 10.1002/adfm.200500334

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      Conjugated polymers and CdSe nanoparticles functionalized with complementary reactive groups are synthesized and manipulated into multilayer structures by using a layer-by-layer (LbL) approach driven by covalent bonding interactions. The resulting uniform and robust thin films (see Figure; ppv: (p-phenylenevinylene), ITO: indium tin oxide) show interesting photovoltaic properties.

    16. Hydrothermal Growth of Manganese Dioxide into Three-Dimensional Hierarchical Nanoarchitectures (pages 549–555)

      Y.-S. Ding, X.-F. Shen, S. Gomez, H. Luo, M. Aindow and S. L. Suib

      Version of Record online: 3 JAN 2006 | DOI: 10.1002/adfm.200500436

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      ϵ-MnO2 with controlled 3D hierarchical nanoarchitectures (see Figure) has been synthesized through a simple hydrothermal process. The self-organized crystals consist of a major ϵ-MnO2 dipyramidal single crystal axis and secondary branches. The formation mechanism is investigated. The synthesized ϵ-MnO2 shows both semiconducting and magnetic properties.

    17. Self-Assembled Shape-Memory Fibers of Triblock Liquid-Crystal Polymers (pages 556–560)

      S. V. Ahir, A. R. Tajbakhsh and E. M. Terentjev

      Version of Record online: 3 JAN 2006 | DOI: 10.1002/adfm.200500692

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      Telechelic triblock copolymers, with the dominant middle block a main-chain nematic polymer, provide a self-assembling material for extruding and drawing aligned fibers (see Figure). The resulting thermoplastic elastomer demonstrates reversible shape memory, contracting and elongating by over 500% on temperature change.

    18. Highly Ordered Mesoporous Silicon Carbide Ceramics with Large Surface Areas and High Stability (pages 561–567)

      Y. F. Shi, Y. Meng, D. H. Chen, S. J. Cheng, P. Chen, H. F. Yang, Y. Wan and D. Y. Zhao

      Version of Record online: 3 JAN 2006 | DOI: 10.1002/adfm.200500643

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      Highly ordered mesoporous SiC with hexagonal (p6m) or bicontinuous cubic (Ia3d) symmetries (see Figure) have been synthesized by using polycarbosilane as a precursor in a one-step nanocasting process. The products have high surface areas (≈720 m2 g–1), narrow pore-size distributions (2.0–3.7 nm), and ultrahigh stability up to 1400 °C.

    19. Stable, Superhydrophobic, and Conductive Polyaniline/Polystyrene Films for Corrosive Environments (pages 568–574)

      Y. Zhu, J. Zhang, Y. Zheng, Z. Huang, L. Feng and L. Jiang

      Version of Record online: 19 JAN 2006 | DOI: 10.1002/adfm.200500624

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      Electrospinning is used to prepare polyaniline/polystyrene films with water contact angles as high as 165° and a sliding angle of less than 5°. The superhydrophobicity and conductivity of the films are stable over a wide pH range, and also in oxidizing solutions. The effect of surface morphology (a typical example is shown in the Figure) on these properties is also investigated.

    20. Highly Efficient Green-Emitting Phosphorescent Iridium Dendrimers Based on Carbazole Dendrons (pages 575–581)

      J. Ding, J. Gao, Y. Cheng, Z. Xie, L. Wang, D. Ma, X. Jing and F. Wang

      Version of Record online: 19 JAN 2006 | DOI: 10.1002/adfm.200500591

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      Solution-processable, green-light-emitting iridium dendrimers based on (up to second-generation) carbazole dendrons exhibit high photoluminescence and electroluminescence quantum efficiencies. With the second-generation dendrimer G2 (see Figure), a maximum luminous efficiency of 34.7 cd A–1 for non-doped devices and 57.9 cd A–1 for doped devices is demonstrated.

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