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SYOO: Organic Optoelectronics and Photonics

SYOO 6: Poster

SYOO 6.8: Poster

Monday, March 7, 2005, 18:00–20:00, Poster TU A

Vacuum deposited composite films for luminescence conversion — •Marieta Levichkova, Jacky Assa, Hartmut Fröb, Robert Gehlhaar, and Karl Leo — Institut für Angewandte Photopysik, TU Dresden, 01062 Dresden, Germany

A possibility for PL conversion of blue-emitting diodes using vacuum deposited composite films on top is investigated. The layers consist of a host material (e.g. Alq3) doped with materials fluorescent in the yellow-red range. The LEDs are used as primary light source for excitation of the host molecules, upon which photon emission at lower energies occurs. The dopants are chosen to absorb in the emitting range of the host. The resulting PL spectra depend on dopant concentration as well as on the total composite film thickness. Chromaticity evaluations undoubtedly confirm that by optimization of the latter parameters, white emitting LEDs could be produced. The results are interpreted by Förster energy transfer between the organic macromolecules. The stability of the systems in dependence on composition is discussed.