Regensburg 2004 – wissenschaftliches Programm

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SYOH: Organic and Hybrid Systems for Future Electronics

SYOH 5: Poster

SYOH 5.77: Poster

Donnerstag, 11. März 2004, 18:00–21:00, B

Fatigue mechanisms of organic light emitting diodes — •Roland Schmechel, Frederik Neumann, Yuri A. Genenko, and Heinz von Seggern — TU-Darmstadt; FB:Material- und Geowissenschaft; Petersenstr.23; D-64287 Darmstadt

A study on possible electrical fatigue mechanisms in organic light emitting diodes (OLEDs) is presented. In order to distinguish bulk and interface properties, electroluminescence (EL) and photoluminescence (PL) intensities are measured simultaneously during device operation. In addition, I-V characteristics were recorded before and after fatigue. Unlike an almost constant PL, a strong decrease in EL is observed indicating an interface related fatigue mechanism. The I-V characteristics differ strongly before and after the device operation, especially in the low forward voltage regime. Whereas the I-V characteristics of the virgin device can be explained by space charge limited currents and field dependent charge carrier mobilities, the fatigued, but still operating device has developed a low Ohmic parallel resistance. At present we conclude that a fatigued device shows additional conductive pathways through the bulk and a disturbed charge carrier balance due to reduced injection of charge carriers.