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Hamburg 2001 – scientific programme

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SYOF: Organische Festkörper

SYOF 5: Poster Session

SYOF 5.39: Poster

Tuesday, March 27, 2001, 17:00–19:00, Aula S3

High efficiency organic light emitting diodes based on triplet harvesting materials — •Arvid Hunze1, Marcus Scheffel1, Jan Birnstock1, Jörg Blässing1, Matthias Stößel1, Karsten Heuser1, Georg Wittmann1, Wolfgang Rogler1, and Albrecht Winnacker21Siemens AG, ZT Mf 1, Paul-Gossen-Str. 100, 91052 Erlangen — 2Universität Erlangen-Nürnberg, Institut für Werkstoffwissenschaften, Martensstr. 7, 91058 Erlangen

One new and promising way to improve the quantum efficiency of organic light emitting diodes (OLEDs) is the usage of electrophosphorescent materials. Due to the long lifetime of triplet excitation of an emitting molecule, phosphorescent decay is suppressed. Thus conventional materials such as Alq3, show emission primarily from singulet excited states. As the ratio between fluorescent singulet and phosphorescent triplet states in small molecule OLEDs is 1:3, the harvesting of triplets is expected to has the potential to increase the luminous efficiency by a factor of four.
Transition metal complexes like Ir[ppy]3 and PtOEP show a fast and efficient phosphorescent decay, leading to very high external quantum efficiencies. We present investigations on electrophosphorescent molecules doped into various charge transport materials. By using combinatorial methods, the dopant concentration is varied over a wide range, and the effects of different concentrations are investigated. 20 cd/A and 15 lm/W at 100 cd/m2 have been reached with devices with Ir[ppy]3 doped in CBP.

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