Advanced Functional Materials

Cover image for Vol. 12 Issue 11‐12

December, 2002

Volume 12, Issue 11-12

Pages 739–837

    1. Perfluorocyclobutane-Based Arylamine Hole-Transporting Materials for Organic and Polymer Light-Emitting Diodes (pages 745–751)

      X.Z. Jiang, S. Liu, M.S. Liu, P. Herguth, A.K.-Y. Jen, H. Fong and M. Sarikaya

      Version of Record online: 23 DEC 2002 | DOI: 10.1002/adfm.200290002

      Highly efficient blue-, green-, and red-emitting polymer LEDs can be fabricated using hole-transporting layers based on triarylamines-containing perfluorocyclobutanes (PFCBs). Energy level studies suggest that ITO can inject holes into the PFCB-based materials efficiently. Moreover, the materials are rather hydrophobic, which could lead to LED devices with much better stabilities against moisture-induced degradation. The Figure shows a PFCB-based film on a quartz substrate.

    2. Temperature-Dependent Photonic Bandgap in a Self-Assembled Hydrogen-Bonded Liquid-Crystalline Diblock Copolymer (pages 753–758)

      C. Osuji, C.-Y. Chao, I. Bita, C.K. Ober and E.L. Thomas

      Version of Record online: 23 DEC 2002 | DOI: 10.1002/adfm.200290003

      A photonic band gap in the visible was produced by self-assembly of hydrogen-bonded liquid-crystalline (LC) block copolymers. Varying the order parameter of the LC domains by heating and cooling modulates the efficiency of the gap (see Figure and cover).

    3. Interactions Between Suspended Nanowires and Patterned Surfaces (pages 759–765)

      B.R. Martin, S.K.St. Angelo and T.E. Mallouk

      Version of Record online: 23 DEC 2002 | DOI: 10.1002/adfm.200290004

      The mobility of monolayer-coated gold nanowires on surfaces depends on the nature of the electrostatic interactions between the particles and the surface. Patterned surfaces (see Figure) are selectively derivatized using a mixture of attractive and repulsive interactions, and nanowire bundles are assembled in the lithographically defined wells of appropriate size.

    4. Template Synthesis of Au/Co Multilayered Nanowires by Electrochemical Deposition (pages 766–772)

      S. Valizadeh, L. Hultman, J.M. George and P. Leisner

      Version of Record online: 23 DEC 2002 | DOI: 10.1002/adfm.200290005

      Au/Co multilayers have been deposited into 20 μm thick ion track etched polycarbonate membranes. The optimal conditions for the electrodeposition of these multilayers have been determined by cyclic voltammetry, chronoamperometry, and pulse-potential experiments in different electrolytes. A dark field TEM image from 2 nm Au/4 nm Co multilayered nanowires reveals dense and well-defined layer interfaces (see Figure).

    5. Emergent Nanostructures: Water-Induced Mesoscale Transformation of Surfactant-Stabilized Amorphous Calcium Carbonate Nanoparticles in Reverse Microemulsions (pages 773–779)

      M. Li and S. Mann

      Version of Record online: 23 DEC 2002 | DOI: 10.1002/adfm.200290006

      Organized surfactant–vaterite nanostructures can be created by the water-induced crystallization of amorphous calcium carbonate (ACC) nanoparticles in water-in-isooctane microemulsions. The crystalline nanostructures develop within primary aggregates of the surfactant-stabilized ACC nanoparticles by in situ mesoscale transformation. The figure shows a TEM image of co-aligned bundles of vaterite nanofilaments prepared by this method.

    6. A Novel Family of Boron-Containing Hole-Blocking Amorphous Molecular Materials for Blue- and Blue–Violet-Emitting Organic Electroluminescent Devices (pages 780–786)

      M. Kinoshita, H. Kita and Y. Shirota

      Version of Record online: 23 DEC 2002 | DOI: 10.1002/adfm.200290007

      A novel family of boron-containing amorphous molecular materials (see Figure), which function efficiently as hole blockers in blue- and blue–violet-emitting organic electroluminescent devices (see inside front cover), has been designed and synthesized. The materials undergo reversible cathodic reduction and readily form stable amorphous glasses with high glass-transition temperatures on cooling from the melt.

    7. Resonant Tunneling Processes along Conjugated Molecular Wires: A Quantum-Chemical Description (pages 787–794)

      Y. Karzazi, J. Cornil and J.-L. Brédas

      Version of Record online: 23 DEC 2002 | DOI: 10.1002/adfm.200290008

      When used as active elements for the fabrication of resonant tunelling diodes, molecular wires inserted into nanopores and contacted by two metallic electrodes can show negative differential resistance in their current/voltage (I/V) characteristics (i.e., a negative slope in the I/V curve). A possible mechanism at the quantum-chemical level, which accounts for the experimental observation of these features in substituted phenylene ethynylene oligomers is developed in this contribution. The results of the calculations provide a general basis to develop strategies for the design of molecular wires displaying this behavior.

    8. Soft Contact Deposition onto Molecularly Modified GaAs. Thin Metal Film Flotation: Principles and Electrical Effects (pages 795–807)

      A. Vilan and D. Cahen

      Version of Record online: 23 DEC 2002 | DOI: 10.1002/adfm.200290009

      Flotation of a thin solid film can be used to trap and preserve a molecular monolayer between the film and a bulk solid phase (see Figure). This provides a way to make solid electrical contacts to molecules. The technical obstacles and solutions to overcome them are discussed. Actual results of metal/molecular monolayer/GaAs devices are presented and the importance of interface morphology for electrical transport through such a structure is illustrated.

    9. Lasing From a Förster Transfer Fluorescent Dye Couple Dissolved in a Chiral Nematic Liquid Crystal (pages 808–810)

      M. Chambers, M. Fox, M. Grell and J. Hill

      Version of Record online: 23 DEC 2002 | DOI: 10.1002/adfm.200290010

      Lasing from a Förster transfer dye couple dissolved in an unconventional, mirrorless resonator; namely, a chiral nematic liquid crystal is demonstrated. The authors find an optically pumped lasing at a threshold as low as 2.1 J m–2. Simultaneous lasing at two widely separated wavelengths is also demonstrated. By wise choice of the sensitizer and emitter dyes, the excitation spectrum can be matched to a pump source. In combination with, for instance, a bright, pulsed light-emitting diode this could create an attractive alternative to the organic injection laser.

    10. Non-Covalent Chemistry on Surface-Confined, Isolated Dendrimers (pages 811–818)

      H.-J. van Manen, T. Auletta, B. Dordi, H. Schönherr, G.J. Vancso, F.C.J.M. van Veggel and D.N. Reinhoudt

      Version of Record online: 23 DEC 2002 | DOI: 10.1002/adfm.200290011

      A “bottom-up” fabrication of nanometer-scale metallodendrimers, embedded in self-assembled monolayers on a gold surface, via non-covalent growth of isolated, nanometer-sized supramolecular structures is presented, as shown in the Figure. The size increase of the isolated dendrimers upon metal–ligand coordination was resolved by ex-situ tapping-mode atomic force microscopy.

    11. Fine-Tuning of the Chromaticity of the Emission Color of Organic–Inorganic Hybrids Co-Doped with EuIII, TbIII, and TmIII (pages 819–823)

      L.D. Carlos, R.A. Sá Ferreira, J.P. Rainho and V. de Zea Bermudez

      Version of Record online: 23 DEC 2002 | DOI: 10.1002/adfm.200290012

      A fine-tuning of the chromaticity of the light emitted from organic–inorganic nanostructured hybrids co-doped with Eu3+, Tb3+, and Tm3+ from red to green is possible. Raising the temperature from 200 to 300 K changes the color smoothly from the yellowish-green region of the spectrum towards the red as shown in t he Figure. This is discussed in terms of thermally activated energy transfer mechanisms from Tb3+ energy states to the hybrid’s emitting levels.