Regensburg 2007 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 16: Organic Light Emitting Diodes (SYOE 9)

DS 16.7: Vortrag

Mittwoch, 28. März 2007, 16:00–16:15, H32

Novel solution processable cathode structures for PLEDs — •Riikka Suhonen^1,2, Andreas Kanitz¹, Wiebke Sarfert¹, Ralph Pätzold¹, and Albrecht Winnacker² — ¹Siemens AG, CT MM1, Günther-Scharowsky-Str. 1, 91058 Erlangen, Germany — ²Department of Material Science VI, University Erlangen-Nuremberg, Martensstraße 7, 91058 Erlangen, Germany

Polymer light-emitting diodes (PLEDs) have attracted much attention due to their potential use in large area, flat-panel displays. The key challenges related to the use in commercial applications are the device stability, device efficiency and the ease of fabrication.

The contacts between the inorganic and organic layers are known to play a crucial role in the PLED device performance. In general, low work function metals like barium or calcium are used to reduce the energy barrier height between the cathode and the polymer. Also the concept of a nanoscale thin interfacial layer of alkali halide salt, such as LiF, has been shown to increase the electron injection in OLEDs and is being widely used. However, both low work function metals and alkali halides are reactive towards atmospheric moisture and oxygen and must be processed under vacuum conditions.

In this contribution, we replace the low work function metals with a thin layer of alkali salt. We show that comparable diode performance can be achieved independent of the deposition method of the thin salt layer. We compare the performance of solution processed and evaporated salt cathodes to the standard barium-aluminum cathode.