Olaf Gelsen - Academia.edu (original) (raw)

Papers by Olaf Gelsen

computationally efficient methods. To address this, we have implemented a parallel Markov Chain M... more computationally efficient methods. To address this, we have implemented a parallel Markov Chain Monte Carlo scheme for sampling the posterior distribution.

ITE Technical Report, 1999

ITE Technical Report, 2000

Le Journal de Physique Colloques, 1989

Speciality Chemicals, 2004

$Research paper thumbnail of Comment on ‘‘Observation of the photorefractive effect in a polymer’’$

Physical Review Letters, 1991

SID Symposium Digest of Technical Papers, 2000

Polymer light-emitting diodes (PLEDs) and displays based on polymer technology have made dramatic... more Polymer light-emitting diodes (PLEDs) and displays based on polymer technology have made dramatic progress during the last years. In particular, efficiency and device lifetime have improved to such a significant extent that first products will commercialized within this year. We report here on the technical status of materials and devices upon which this success is based. Efficiency and especially operational stability are now at a level which easily meets the requirements for a variety of applications, namely power efficiencies are well above 10 lm/W, operational lifetimes are exceeding 20000 hours at display brightness levels and room temperature). This progress has been achieved by the careful analysis of failure mechanisms and the systematic improvement of materials. The first products, i. e. back-lights (for LCD-displays), segmented displays, and finally passive-matrix-addressed low-information-content (LIC) graphical displays are described. Light emitting polymerss are now manufactured on industrial scale under high purity conditions; filling and packaging is done under a class 10 clean room condition. For details see H. Becker Paper 46.1.

Springer Series in Solid-State Sciences, 1992

We report transient absorption measurements using the pump and probe technique on poly(2,5 dimeth... more We report transient absorption measurements using the pump and probe technique on poly(2,5 dimethoxy-p-phenylene vinylene), DMPPV, and poly(p-phenylene vinylene), PPV. We observe a transient absorption in both materials, although a transient bleaching would be expected, and we discuss possible explanations for this behaviour.

Synthetic Metals, 2000

Ž .Ž. Poly p-phenylene vinylene s PPVs are promising materials for optoelectronic applications, e... more Ž .Ž. Poly p-phenylene vinylene s PPVs are promising materials for optoelectronic applications, especially for displays based on polymer Ž. light emitting diodes PLEDs. We report here our findings concerning defect structures in this class of materials and the implications of the discovered irregularities on important material properties, that is, the operational life in a PLED. Recent improvements, which were deduced from this findings, are presented: optimized PPVs with a lower amount of defects result in a strong increase of operational lifetime.

Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 1992

We report spectrally resolved electroabsorption (EA) measurements on poly(arylene vinylene)s. The... more We report spectrally resolved electroabsorption (EA) measurements on poly(arylene vinylene)s. The materials poly(thienylene vinylene), PTV, and poly(p-phenylene vinylene), PPV, are particularly attactive as they can be prepared from soluble precursors which allow ready fabrication of films. The subsequent thermal conversion of the precursor yields samples with good optical and mechanical properties and environmental stability. Both materials give a strong electro-optic

Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 1994

Abstract Electric field induced changes in the optical properties of poly (3-octylthiophene) in t... more Abstract Electric field induced changes in the optical properties of poly (3-octylthiophene) in the spectral region of the lowest π-π* electronic transition are reported. The electroabsorption [EA] resembles the first energy derivative of the unperturbed spectrum, scales quadratically with the applied electric field, and its lineshape is field invariant, all consistent with a DC Kerr effect whose origin is the Stark shift of a singlet exciton. In addition, a transition that does not appear in the unperturbed absorption spectrum is detected and ...

Journal of Applied Physics, 1992

We report the results of a spectroscopic investigation of the quadratic electro‐optic nonlinearit... more We report the results of a spectroscopic investigation of the quadratic electro‐optic nonlinearity in poly(2,5‐thienylene vinylene). Electroabsorption spectra closely resemble the second energy derivative of the unperturbed π‐π* absorption and show oscillations associated with the strong vibronic features present therein. The dispersion of both the real and imaginary parts of χ(3) (−ω;0,0,ω) has been determined and we find that Re{χ(3)} has a peak value of 7.5×10−9 esu at 1.83 eV and Im{χ(3)} has a peak value of 6.2×10−9 esu at 1.78 eV. This nonlinearity is responsible for a photorefractive effect under resonant photoexcitation.

Advanced Materials, 1993

Halliday, DA, Burn, PL, Bradley, DDC, Friend, RH, Gelsen, OM, Holmes, AB, Kraft, A., Martens, JHF... more Halliday, DA, Burn, PL, Bradley, DDC, Friend, RH, Gelsen, OM, Holmes, AB, Kraft, A., Martens, JHF and Pichler, K.(1993), Large changes in optical response through chemical pre-ordering of poly (p-phenylenevinylene). Advanced Materials, 5: 4043. doi: 10.1002/ ...