Advanced Functional Materials

Cover image for Vol. 19 Issue 13

July 10, 2009

Volume 19, Issue 13

Pages 2019–2174

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Full Papers
    6. Frontispiece
    7. Full Papers
    8. Index
    1. Polyfluorene Light-Emitting Diodes: Understanding the Nature of the States Responsible for the Green Emission in Oxidized Poly(9,9-dialkylfluorene)s: Photophysics and Structural Studies of Linear Dialkylfluorene/Fluorenone Model Compounds (Adv. Funct. Mater. 13/2009)

      Khai Leok Chan, Marc Sims, Sofia I. Pascu, Marilù Ariu, Andrew B. Holmes and Donal D. C. Bradley

      Article first published online: 6 JUL 2009 | DOI: 10.1002/adfm.200990055

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      Polyfluorenes, whilst attractive candidates for polymer light-emitting diodes, are susceptible to oxidative degradation. This degradation results in significant green emission. Although it has been linked to the formation of fluorenones, the precise relationship between fluorenones and the observed color shift remains widely debated. On page 2147, Chan et al. report a study on this relationship with the use of a series of model compounds. Inter-molecular fluorenone–fluorenone interaction is reported to be an essential requirement for the color shift.

  2. Inside Front Cover

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Full Papers
    6. Frontispiece
    7. Full Papers
    8. Index
    1. Pigment Synthesis: PY181 Pigment Microspheres of Nanoplates Synthesized via Polymer-Induced Liquid Precursors (Adv. Funct. Mater. 13/2009)

      Yurong Ma, Gerald Mehltretter, Carsten Plüg, Nadine Rademacher, Martin U. Schmidt and Helmut Cölfen

      Article first published online: 6 JUL 2009 | DOI: 10.1002/adfm.200990056

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      A polymer-induced liquid precursor is used for a pigment yellow 181 crystal formed by chemical reaction in mixed solvents of water and isopropanol by direct azo coupling under the directing influence of a designed copolymer additive. This leads to a pigment with novel complex morphology and unusal properties, as shown by Cölfen et al. on page 2095.

  3. Contents

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Full Papers
    6. Frontispiece
    7. Full Papers
    8. Index
    1. Contents: (Adv. Funct. Mater. 13/2009) (pages 2019–2026)

      Article first published online: 6 JUL 2009 | DOI: 10.1002/adfm.200990057

  4. Full Papers

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Full Papers
    6. Frontispiece
    7. Full Papers
    8. Index
    1. Tuning the Thermal Relaxation of a Photochromic Dye in Functionalized Mesoporous Silica (pages 2027–2037)

      Lea A. Mühlstein, Jürgen Sauer and Thomas Bein

      Article first published online: 14 MAY 2009 | DOI: 10.1002/adfm.200801619

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      It is shown that the kinetics of the back-switching reaction of a photochromic spirooxazine dye encapsulated in mesoporous silica materials can be significantly influenced both by the space available to the dye molecules and by the functionalization of the silica wall (see figure). This is particularly interesting for applications requiring a fast or slow fading speed.

    2. Ionic Iridium(III) Complexes with Bulky Side Groups for Use in Light Emitting Cells: Reduction of Concentration Quenching (pages 2038–2044)

      Carsten Rothe, Chien-Jung Chiang, Vygintas Jankus, Khalid Abdullah, Xianshun Zeng, Rukkiat Jitchati, Andrei S. Batsanov, Martin R. Bryce and Andrew P. Monkman

      Article first published online: 14 APR 2009 | DOI: 10.1002/adfm.200801767

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      A high brightness of ca. 1000 cd m−2 is achieved for orange solid-state light- emitting cells fabricated by solution processing of ionic iridium complexes with bulky ligands. The fluorenyl substituents suppress concentration quenching and increase the lifetime of the excited state.

    3. Plasmonic Enhancement or Energy Transfer? On the Luminescence of Gold-, Silver-, and Lanthanide-Doped Silicate Glasses and Its Potential for Light-Emitting Devices (pages 2045–2052)

      Maik Eichelbaum and Klaus Rademann

      Article first published online: 10 JUN 2009 | DOI: 10.1002/adfm.200801892

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      Tunable multi-colored light-emitting devices (pumped with a blue LED) based on a luminescence energy transfer process between tiny gold and silver clusters and lanthanide(III) ions in silicate glasses can be generated by synchrotron X-ray irradiation. The sensitizing effect of the small noble metal particles consisting of only a few atoms can tremendously enhance the lanthanide luminescence up to a factor of 250.

    4. Unraveling Deterministic Mesoscopic Polarization Switching Mechanisms: Spatially Resolved Studies of a Tilt Grain Boundary in Bismuth Ferrite (pages 2053–2063)

      Brian J. Rodriguez, Samrat Choudhury, Y. H. Chu, Abhishek Bhattacharyya, Stephen Jesse, Katyayani Seal, Arthur P. Baddorf, R. Ramesh, Long-Qing Chen and Sergei V. Kalinin

      Article first published online: 12 MAY 2009 | DOI: 10.1002/adfm.200900100

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      The deterministic mesoscopic mechanism of ferroelectric domain nucleation is investigated at a grain boundary defect using a combination of switching spectroscopy, piezoresponse force microscopy, and phase field modeling. This approach allows the interplay between ferroelectric and ferroelastic wall energies, depolarization fields, and interface charge to be elucidated. The spatial distribution of the calculated nucleation voltage across the defect is shown.

    5. Formation of Highly Luminescent Supramolecular Architectures Possessing Columnar Order from Octupolar Oxadiazole Derivatives: Hierarchical Self-Assembly from Nanospheres to Fibrous Gels (pages 2064–2073)

      Shinto Varghese, Nambalan S. Saleesh Kumar, Anjali Krishna, Doddamane S. Shankar Rao, Subbarao Krishna Prasad and Suresh Das

      Article first published online: 28 MAY 2009 | DOI: 10.1002/adfm.200801902

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      Octupolar oxadiazole derivatives, exhibiting columnar mesophases and capable of hierarchical self-assembly in solutions into highly luminescent nanospheres, fibers, and gels, wherein the columnar organization of the disk shaped chromophores lead to exciton migration and subsequent emission from the J-traps, are reported.

    6. Electroaddressing of Cell Populations by Co-Deposition with Calcium Alginate Hydrogels (pages 2074–2080)

      Xiao-Wen Shi, Chen-Yu Tsao, Xiaohua Yang, Yi Liu, Peter Dykstra, Gary W. Rubloff, Reza Ghodssi, William E. Bentley and Gregory F. Payne

      Article first published online: 14 MAY 2009 | DOI: 10.1002/adfm.200900026

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      Calcium alginate hydrogels can be electrodeposited at electrode addresses without the need for reagents. Mechanistically, anodic signals trigger a localized solubilization of CaCO3 and the release of Ca2+ induces the spatially controlled formation of calcium alginate hydrogels. Alginate electrodeposition is sufficiently mild that bacterial cell populations co-deposited within the hydrogel are viable, grow, and respond to externally added inducers and signaling molecules.

    7. Ligand-Driven Wavelength-Tunable and Ultra-Broadband Infrared Luminescence in Single-Ion-Doped Transparent Hybrid Materials (pages 2081–2088)

      Shifeng Zhou, Nan Jiang, Botao Wu, Jianhua Hao and Jianrong Qiu

      Article first published online: 12 MAY 2009 | DOI: 10.1002/adfm.200800986

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      By tailoring the local ligand field around the active centers, Ni2+ doped hybrid materials show ultra-broadband infrared luminescence covering the whole near-infrared region from 1 100 to 1 800 nm, with the largest full width at half maximum being about 400 nm. The luminescence wavelength can be finely tuned from 1 300 to 1 450 and to 1 570 nm.

    8. Interfacial Polar-Bonding-Induced Multifunctionality of Nano-Silicon in Mesoporous Silica (pages 2089–2094)

      Jung Y. Huang, Jia M. Shieh, Hao C. Kuo and Ci L. Pan

      Article first published online: 4 JUN 2009 | DOI: 10.1002/adfm.200801336

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      A new class of multifunctional materials is realized by using semiconductor nanocrystals for optical sensing and interfacial polar layers to facilitate carrier transport and emulate a ferroelectric-like switching. The artificially engineered optoelectronic material is prepared by preferentially growing silicon nanocrystals on the bottom of the pore-channels of mesoporous silica. The nanocrystals form highly stable one-side bonded interface structures, revealing a strong electron–phonon coupling and a ferroelectric-like hysteretic property.

    9. PY181 Pigment Microspheres of Nanoplates Synthesized via Polymer-Induced Liquid Precursors (pages 2095–2101)

      Yurong Ma, Gerald Mehltretter, Carsten Plüg, Nadine Rademacher, Martin U. Schmidt and Helmut Cölfen

      Article first published online: 28 MAY 2009 | DOI: 10.1002/adfm.200900316

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      Via a polymer-induced liquid precursor phase, stable PY181 microspheres of nanoplates in β-phase are obtained in water/isopropanol solvent mixtures by direct azo coupling under the directing influence of a designed copolymer additive. This is the first time that the β-phase is directly produced in non-needle-like morphology and that a polymer-induced liquid precursor is observed for a crystal formed by a chemical reaction.

    10. Structural and Room-Temperature Transport Properties of Zinc Blende and Wurtzite InAs Nanowires (pages 2102–2108)

      Shadi A. Dayeh, Darija Susac, Karen L. Kavanagh, Edward T. Yu and Deli Wang

      Article first published online: 12 MAY 2009 | DOI: 10.1002/adfm.200801307

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      The microstructure and charge-transport properties of InAs nanowires are shown to be correlated. Spontaneous polarization charges in wurtzite (WZ) InAs nanowire field-effect transistors (NWFETs) help suppress surface-state charges and improve the NWFET subthreshold characteristics when compared to those of pure zinc blende (ZB) NWFETs (see central figure). The contour plots (left and right) show the carrier concentration (n) within the NWFETs.

    11. Cu(II)-Azabis(oxazoline)-Complexes Immobilized on Superparamagnetic Magnetite@Silica-Nanoparticles: A Highly Selective and Recyclable Catalyst for the Kinetic Resolution of 1,2-Diols (pages 2109–2115)

      Alexander Schätz, Markus Hager and Oliver Reiser

      Article first published online: 21 MAY 2009 | DOI: 10.1002/adfm.200801861

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      Copper(II)-azabis(oxazolines) are grafted on magnetite@silica nanoparticles via click chemistry, resulting in a highly selective heterogeneous nanocomposite that can be efficiently recycled through magnetic decantation. The catalysts are used for up to five iterative runs in the asymmetric benzoylation of 1,2-diols with consistent high activity or enantioselectivity.

    12. Determination of Size, Morphology, and Nitrogen Impurity Location in Treated Detonation Nanodiamond by Transmission Electron Microscopy (pages 2116–2124)

      Stuart Turner, Oleg I. Lebedev, Olga Shenderova, Igor I. Vlasov, Jo Verbeeck and Gustaaf Van Tendeloo

      Article first published online: 12 MAY 2009 | DOI: 10.1002/adfm.200801872

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      The effects of temperature treatment and cleaning procedures on the particle size, morphology and nitrogen impurity location in detonation nanodiamond samples are studied by transmission electron microscopy. High resolution imaging shows the possibility of nanodiamond size control by high-temperature annealing. Detailed electron energy-loss spectroscopy evidences tetrahedral nitrogen impurity incorporation in the diamond cores of all nanodiamond samples.

    13. Synthesis of Microporous Carbon Nanofibers and Nanotubes from Conjugated Polymer Network and Evaluation in Electrochemical Capacitor (pages 2125–2129)

      Xinliang Feng, Yanyu Liang, Linjie Zhi, Arne Thomas, Dongqing Wu, Ingo Lieberwirth, Ute Kolb and Klaus Müllen

      Article first published online: 12 MAY 2009 | DOI: 10.1002/adfm.200900264

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      1D fibers and tubes are constructed through the oriented carbon–carbon crosslinking reactions towards rigid conjugated polymer networks. As the result, a template-free and one-step synthesis of CNTs and CNFs are achieved through a simple carbonization of the as-formed carbon-rich tubular and fiberlike polyphenylene precursors under argon. Microporous CNTs and CNFs with a surface area up to 900 m2 g−1 are obtained.

    14. Optically-Pumped Lasing in Hybrid Organic–Inorganic Light-Emitting Diodes (pages 2130–2136)

      Myoung Hoon Song, Dinesh Kabra, Bernard Wenger, Richard H. Friend and Henry J. Snaith

      Article first published online: 14 MAY 2009 | DOI: 10.1002/adfm.200801833

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      An airstable hybrid LED is made by using metal oxide inter-layers, which act as charge injecting layers and also provide good photonic structure to enhance efficiency for polymer LEDs by keeping the optical modes away from lossy electrodes. Incorporating distributed feedback into these hybrid LEDs shows high optical gain in the active polymer medium which supports low threshold lasing under optical excitation.

  5. Frontispiece

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Full Papers
    6. Frontispiece
    7. Full Papers
    8. Index
    1. Nanodot Formation: Spontaneous Outcropping of Self-Assembled Insulating Nanodots in Solution-Derived Metallic Ferromagnetic La0.7Sr0.3MnO3 Films (Adv. Funct. Mater. 13/2009)

      César Moreno, Patricia Abellán, Awatef Hassini, Antoine Ruyter, Angel Pérez del Pino, Felip Sandiumenge, Marie-Jose Casanove, José Santiso, Teresa Puig and Xavier Obradors

      Article first published online: 6 JUL 2009 | DOI: 10.1002/adfm.200990058

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      Epitaxial self-assembled Sr-La oxide insulating nanodots are formed through a new mechanism at the surface of an epitaxial metallic ferromagnetic La0.7Sr0.3MnO3 film grown on SrTiO3 from chemical solutions, as reported by C. Moreno et al. on page 2139. TEM analysis reveals that, underneath the La-Sr oxide nanodots, the film switches from the compressive out-of-plane stress component to a tensile component.

  6. Full Papers

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Full Papers
    6. Frontispiece
    7. Full Papers
    8. Index
    1. Spontaneous Outcropping of Self-Assembled Insulating Nanodots in Solution-Derived Metallic Ferromagnetic La0.7Sr0.3MnO3 Films (pages 2139–2146)

      César Moreno, Patricia Abellán, Awatef Hassini, Antoine Ruyter, Angel Pérez del Pino, Felip Sandiumenge, Marie-Jose Casanove, José Santiso, Teresa Puig and Xavier Obradors

      Article first published online: 2 JUN 2009 | DOI: 10.1002/adfm.200900095

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      Self-assembled insulating nanoislands spontaneously outcrop on top of metallic LSMO to decrease the total elastic energy of the nanocomposite film. TEM and AFM images display polyhedral islands with homogeneous size. The size and concentration of surface islands can be controlled through growth kinetics and the initial composition of the chemical solutions.

    2. Understanding the Nature of the States Responsible for the Green Emission in Oxidized Poly(9,9-dialkylfluorene)s: Photophysics and Structural Studies of Linear Dialkylfluorene/Fluorenone Model Compounds (pages 2147–2154)

      Khai Leok Chan, Marc Sims, Sofia I. Pascu, Marilù Ariu, Andrew B. Holmes and Donal D. C. Bradley

      Article first published online: 22 APR 2009 | DOI: 10.1002/adfm.200801792

      Thumbnail image of graphical abstract

      The nature of green emission in polyfluorene is investigated using a series of structurally well-defined model compounds comprising dihexylfluorene and fluorenone moieties. Optical measurements show that molecule–molecule interaction is essential in activating the green emission band, and XRD suggests that the interaction is influenced by dipole–dipole coupling between neighboring fluorenone moieties.

    3. Repeated Transfer of Colloidal Patterns by Using Reversible Buckling Process (pages 2155–2162)

      Dong Choon Hyun, Geon Dae Moon, Eun Chul Cho and Unyong Jeong

      Article first published online: 8 JUN 2009 | DOI: 10.1002/adfm.200900202

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      Identical patterns of self-assembled colloids on flat surfaces are repeatedly obtained by transferring assembled colloids from buckling patterns. The keys to success are the reversible nature of buckling and the reduced buckling amplitude upon poststretching of the substrates. Complex patterns composed of solid colloids, hydrogel colloids, and inorganic nanoparticles are demonstrated.

    4. Surface Design in Solid-State Dye Sensitized Solar Cells: Effects of Zwitterionic Co-adsorbents on Photovoltaic Performance (pages 2163–2172)

      Mingkui Wang, Carole Grätzel, Soo-Jin Moon, Robin Humphry-Baker, Nathalie Rossier-Iten, Shaik M. Zakeeruddin and Michael Grätzel

      Article first published online: 12 MAY 2009 | DOI: 10.1002/adfm.200900246

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      Charge recombination at the dye-hole transporting material interface plays a critical role in the cell efficiency in solid-state dye sensitized solar cells. In this study influence from the zwitterionic co-adsorbents (4-guanidinobutyric Acid (GBA) and 4-aminobutyric Acid (ABA)) used in the solid-state DSC is discussed. Important information on the charge recombination across the dye sensitized heterojunction is gathered in this fashion.

  7. Index

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Full Papers
    6. Frontispiece
    7. Full Papers
    8. Index

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