Pulsed Excitation of OLEDs With a Remote Metallic Cathode

In this paper, we report on the behavior of organic LEDs (OLEDs) with a remote metallic cathode under pulsed excitation. Devices comprising poly(triarylamine) as the hole-transporting layer, Alq₃:DCM₂ as the light-emitting layer, and PTCDI-C₁₃H₂₇ as the electron-transporting layer are analyzed and their performance is compared to conventional OLED device structures comprising the same organic materials. We demonstrate that the dependence of the light intensity on the applied pulsewidth is mainly determined by charge injection into the active light-emitting layer and show that pulses down to 1 ¿s can be applied to the device without affecting the light intensity. This latter observation suggests that pulsed excitation may be able to reduce the accumulation of triplets in the device. In this way, triplet-state losses, which are major loss mechanisms with respect to the high photon density required for an electrically pumped organic laser, will be suppressed.