Regensburg 2010 – scientific programme

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DS: Fachverband Dünne Schichten

DS 29: Poster: Molecular Spintronics, Biomolecular and Functional Organic Layers, Organic Electronics and Photovoltaics, Plasmonics and Nanophotonics, Organic Thin Films, Nanoengineered Thin Films, Thin Film Characterisation,

DS 29.22: Poster

Wednesday, March 24, 2010, 15:00–17:30, Poster A

Waveguide and surface plasmon losses in organic light-emitting diodes (OLED’s) — •Bert Scholz, Jörg Frischeisen, and Wolfgang Brütting — Institute of Physics, University of Augsburg, Germany

As a new technology in light sources the organic light-emitting diodes (OLEDs) have improved rapidly in recent years. One of the remaining challenges is to enhance light outcoupling. Especially the excitation of waveguide modes (WGMs) inside the organic layers and surface plasmons (SPs) at the interface to the cathode strongly reduce the efficiency. These loss channels usually are not accessible for a profound analysis. Therefore, we investigate a simplified OLED stack consisting of only a glass substrate, a metallic silver layer and Alq₃ (tris-(8-hydroxyquinoline) aluminum). In this stack it is possible to extract and measure WGMs as leaky modes and to couple out SPs by a reversed Kretschmann configuration. The occurrence and extraction of WGMs and SPs is studied in detail by varying the thickness of the silver and the Alq₃ layer and by a comparison to numerical simulations. The results obtained in this study offer a deeper understanding of WGMs and SPs, which is a first step to reduce these optical losses and to significantly enhance the efficiency of OLEDs.