@article{SaphiannikovaNeher2005,
  author    = {Saphiannikova, Marina and Neher, Dieter},
  title     = {Thermodynamic theory of light-induced material transport in amorphous azobenzene polymer films},
  issn      = {1520-6106},
  year      = {2005},
  abstract  = {It was discovered 10 years ago that the exposure of an initially flat layer of an azobenzene-containing polymer to an inhomogeneous light pattern leads to the formation of surface relief structures, accompanied by a mass transport over several micrometers. However, the driving force of this process is still unclear. We propose a new thermodynamic approach that explains a number of experimental findings including the light-induced deformation of free-standing films and the formation of surface relief gratings for main inscription geometries. Our basic assumption is that under homogeneous illumination, an initially isotropic sample should stretch itself along the polarization direction to compensate the entropy decrease produced by the photoinduced reorientation of azobenzene chromophores. The magnitude of the elastic stress, estimated by taking the derivative of the free energy over the sample deformation, is shown to be sufficient to induce plastic deformation of the polymer film. Orientational distributions of chromophores predicted by our model are compared with those deduced from Raman intensity measurements},
  language  = {en}
}
@article{KulikovskyNeherMecheretal.2004,
  author    = {Kulikovsky, Lazar and Neher, Dieter and Mecher, E. and Meerholz, Klaus and Horhold, H. H. and Ostroverkhova, O.},
  title     = {Photocurrent dynamics in a poly(phenylene vinylene)-based photorefractive composite},
  issn      = {1098-0121},
  year      = {2004},
  abstract  = {All parameters describing the charge carrier dynamics in a poly(phenylene vinylene)-based photorefractive (PR) composite relevant to PR grating dynamics were determined using photoconductivity studies under various illumination conditions. In particular, the values of the coefficients for trap filling and recombination of charges with ionized sensitizer molecules could be extracted independently. It is concluded that the PR growth time without preillumination is mostly determined by the competition between deep trap filling and recombination with ionized sensitizer molecules. Further, the pronounced increase in PR speed upon homogeneous preillumination (gating) as reported recently is quantitatively explained by deep trap filling},
  language  = {en}
}
@article{BagnichBasslerNeher2005,
  author    = {Bagnich, Sergey A. and Bassler, H. and Neher, Dieter},
  title     = {Exciton dynamics in ladder-type methyl-poly(para-phenylene) doped with phosphorescent dyes},
  issn      = {0022-2313},
  year      = {2005},
  abstract  = {The luminescence of a ladder-type methyl-poly(para-phenylene) (MeLPPP) doped with platinum-porphyrin dye PtOEP covering the concentration 10(-3)-5\% by weight has been measured employing cw and transient techniques. Upon excitation into the range of absorption of the host, strong phosphorescence of the dopant is observed. Possible ways of populating the dopant triplet state are considered. (c) 2004 Elsevier B.V. All rights reserved},
  language  = {en}
}
@article{GalbrechtYangNehlsetal.2005,
  author    = {Galbrecht, Frank and Yang, X. H. and Nehls, B. S. and Neher, Dieter and Farrell, Tony and Scherf, Ullrich},
  title     = {Semiconducting polyfluorenes with electrophosphorescent on-chain platinum-salen chromophores},
  issn      = {1359-7345},
  year      = {2005},
  abstract  = {The synthesis of statistical fluorene-type copolymers with on-chain Pt-salen phosphorescent units and their use in electrophosphorescent OLEDs is reported},
  language  = {en}
}
@article{StillerKarageorgievGeueetal.2004,
  author    = {Stiller, Burkhard and Karageorgiev, Peter and Geue, Thomas and Morawetz, Knut and Saphiannikova, Marina and Mechau, Norman and Neher, Dieter},
  title     = {Optically induced mass transport studied by scanning near-field optical- and atomic force microscopy},
  issn      = {0204-3467},
  year      = {2004},
  abstract  = {Some functionalised thin organic films show a very unusual property, namely the light induced material transport. This effect enables to generate three-dimensional structures on surfaces of azobenzene containing films only caused by special optical excitation. The physical mechanisms underlying this phenomenon have not yet been fully understood, and in addition, the dimensions of structures created in that way are macroscopic because of the optical techniques and the wavelength of the used light. In order to gain deeper insight into the physical fundamentals of this phenomenon and to open possibilities for applications it is necessary to create and study structures not only in a macroscopic but also in nanometer range. We first report about experiments to generate optically induced nano structures even down to 100 nm size. The optical stimulation was therefore made by a Scanning Near-field Optical Microscope (SNOM). Secondly, physical conditions inside optically generated surface relief gratings were studied by measuring mechanical properties with high lateral resolution via pulse force mode and force distance curves of an AFM},
  language  = {en}
}
@article{YangNeher2004,
  author    = {Yang, X. H. and Neher, Dieter},
  title     = {Polymer electrophosphorescence devices with high power conversion efficiencies},
  issn      = {0003-6951},
  year      = {2004},
  abstract  = {We demonstrate efficient single-layer polymer phosphorescent light-emitting devices based on a green-emitting iridium complex and a polymer host co-doped with electron-transporting and hole-transporting molecules. These devices can be operated at relatively low voltages, resulting in a power conversion efficiency of up to 24 lm/W at luminous efficiencies exceeding 30 cd/A. The overall performances of these devices suggest that efficient electrophosphorescent devices with acceptable operating voltages can be achieved in very simple device structures fabricated by spin coating. (C) 2004 American Institute of Physics},
  language  = {en}
}
@article{YangNeherHerteletal.2004,
  author    = {Yang, X. H. and Neher, Dieter and Hertel, D. and Daubler, T. K.},
  title     = {Highly efficient single-layer polymer electrophosphorescent devices},
  issn      = {0935-9648},
  year      = {2004},
  abstract  = {A commercially available Ir complex has been employed for the preparation of highly efficient (see Figure) single-layer phosphorescent polymer light,emitting diodes by use of appropriate thermal treatment and proper adjustment of the layer composition. These devices exhibit essentially no dependence of the driving field on the concentration of the Ir complex, suggesting that the build-up of space-charge in the layer is insignificant},
  language  = {en}
}
@article{SrikhirinCimrovaSchieweetal.2002,
  author    = {Srikhirin, T. and Cimrova, V. and Schiewe, B. and Tzolov, M. and Hagen, R. and Kostromine, S. and Bieringer, Thomas and Neher, Dieter},
  title     = {An Investigation of the photoinduced changes of absoprtion of high-performance photoaddressable Polymers},
  year      = {2002},
  language  = {en}
}
@article{SianovaZenNothoferetal.2002,
  author    = {Sianova, D. and Zen, Achmad and Nothofer, Heinz-Georg and Asawapirom, Udom and Scherf, Ullrich and Hagen, R. and Bieringer, Thomas and Kostromine, S. and Neher, Dieter},
  title     = {Photoaddressable alignment layers for fluorescent polymers in polarized electroluminescence devices},
  year      = {2002},
  language  = {en}
}
@article{WilsonSteffenMcKenzieetal.2002,
  author    = {Wilson, J. N. and Steffen, W. and McKenzie, T. G. and Lieser, G. and Oda, Masao and Neher, Dieter and Bunz, Uwe H. F.},
  title     = {Chiroptcial properties of poly(p-phenyleneethynylene) copolymers in thin films : large g-values},
  year      = {2002},
  language  = {en}
}