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CPP: Chemische Physik und Polymerphysik

CPP 23: POSTER Functional Organic Thin Films

CPP 23.40: Poster

Donnerstag, 30. März 2006, 17:00–19:00, P2

The different effect of anode/organic-interlayers on electrical fatigue and photodegradation of organic light emitting diodes — •Arne Fleissner, Christian Melzer, Roland Schmechel, and Heinz von Seggern — Electronic Materials Department, Institute of Materials Science, Darmstadt University of Technology, Petersenstr. 23, 64287 Darmstadt, Germany

Recently, the photodegradation of organic light emitting diodes (OLEDs) due to the exposure to visible and near-ultraviolet light through the Indium Tin Oxide (ITO) anode has been investigated [J. Appl. Phys. 97, 124501 (2005)]. The ITO/organic-interface and the occurrence of excited organic molecules has been identified as crucial. Introducing appropriate interlayers between ITO and organic, e.g. a thin film of pentacene, suppressed the photodegradation. However, a PEDOT:PSS interlayer did not. In this work, the influence of such anode/organic-interlayers on electrical fatigue is studied. For that purpose, OLEDs with different interlayers between ITO and organic are operated in constant current mode while the time dependent driving voltage, electroluminescence intensity, and photoluminescence intensity are measured. The PEDOT:PSS interlayer shows a remarkable difference in the two degradation modes: It decreases electrical fatigue, however, it does not suppress photodegradation. The different role of PEDOT:PSS in photodegradation and electrical fatigue and the underlying mechanisms are discussed.