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HL: Halbleiterphysik

HL 19: Symposium: Organische Halbleiterbauelemente

HL 19.1: Fachvortrag

Dienstag, 23. März 1999, 16:00–16:35, H1

LED from evaporated organic layers — •Wolfgang Kowalsky, Dirk Metzdorf, Helge Neuner, Hans-Hermann Johannes, Torsten Benstem, and Jörg Schöbel — Institut für Hochfrequenztechnik, TU Braunschweig, Postfach 3329, 38023 Braunschweig, Germany

In recent years, considerable efforts have been directed at developing power-efficient light emitting diodes based on evaporated layers of organic semiconductors. Well-known companies and institutions are occupied with this most promising technology which is considered to get a high market potential. Up to now OLEDs have reached such a high level that they will get into a marketable commodity in the near future as active pixels in flat panel displays. Due to this fact improved fabrication techniques are necessary to obtain highly stable and efficient OLEDs. The complete organic layer sequence and the metallization are deposited in a single process in an UHV-OMBD system (ultra-high vacuum-organic molecular beam deposition). The OLED pixels are defined by conventional photolithography. Different device structures with emission in the blue, green and red spectral region are discussed with respect to their optical and electrical characteristics. Blue and green OLEDs based on Alq3, OXD-8 and AZM-Hex attain efficiencies up to 4 lm/W and luminances of 2*10⁴ cd /m². Improved performance data are attained by doped emission layers. Using Qd doped Alq3 we observe luminances of 2*10⁵ cd /m² and efficiencies up to 8 lm/W.