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SYSA: Symposium Tayloring Organic Interfaces: Molecular Structures and Applications

SYSA 5: Poster Session SYSA

SYSA 5.65: Poster

Dienstag, 26. Februar 2008, 14:30–20:00, Poster A

White top emitting OLED with angle independent emission characteristic — •Michael Thomschke, Patricia Freitag, Gregor Schwartz, Robert Nitsche, Karsten Walzer, and Karl Leo — Technische Universität Dresden, Institut für Angewandte Photophysik, Georg-Bähr-Straße 1, 01062 Dresden, Germany

The general device structure of a top emitting organic light emitting diode (OLED) consists of several organic layers sandwiched in between two metal contacts, with the top one being semitransparent for light outcoupling reasons. Due to the high reflectivity of the electrodes, strong microcavity effects occur which lead to a preferred emission of light of a certain wavelength with main outcoupling in forward direction. This creates rather narrow emission bands, accompanied by strong spectral shifts upon viewing angle variation [1].

By using an organic capping layer on top of the semitransparent metal contact, this unwanted effect can be reduced. This is important especially for white light emission for the use of OLEDs in future lighting applications. Our optical simulations show that the strong angular dependence of the emission color almost vanishes. To verify the simulations we study white top emitting OLEDs based on an approach of Schwartz [2] which are adapted to the top emitting case.

[1] Q. Huang, K. Walzer, M. Pfeiffer, K. Leo, M. Hofmann, T. Stübinger, J. Appl. Phys. 100 64507 (2006)

[2] G. Schwartz, K. Fehse, M. Pfeiffer, K. Walzer, K. Leo, Appl. Phys. Let. 89 083509 (2006)