Dresden 2006 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 23: POSTER Functional Organic Thin Films
CPP 23.30: Poster
Donnerstag, 30. März 2006, 17:00–19:00, P2
Top emitting organic light emitting diodes with improved outcoupling efficiency by organic capping layer — •Qiang Huang1, Karsten Walzer1, Martin Pfeiffer1, Gufeng He1, Karl Leo1, Michael Hofmann2, and Thomas Stübinger2 — 1Institut für Angewandte Photophysik, TU Dresden, D-01062 Dresden, Germany — 2Novaled GmbH, Tatzberg 49, D-01307 Dresden, Germany
The improvement of light outcoupling from organic LEDs is a significant way for increasing the device efficiency. One way to reach this is the use of organic outcoupling layers. We study the emission properties of top emitting OLEDs with different organic capping layer thickness to understand the effect of the capping layer. The distribution pattern of the emitted light from a top emitting OLED depends strongly on the capping layer thickness, with a maximum enhancement of current efficiency by 38%, and quantum efficiency by 35%. This enhancement is not due to the redistribution of emitted light but mainly due to the improvement of outcoupling efficiency by changing the overall optical device structure. At 90 nm capping layer thickness, the device has optimum performance, showing 78 cd/A at 1000 cd/m2 in forward direction as well as a quantum efficiency of 17.8 % and power efficiency of 69 lm/W.
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