Degradation studies on high-voltage-driven organic light-emitting device using in situ on-operation method with scanning photoelectron microscopy

Abstract

We investigated the degradation behavior of a high-voltage-driven organic light-emitting device (OLED) by operating the device in an ultrahigh-vacuum environment. In situ on-operation method provided the initial degradation process when the OLED was biased inside an analysis chamber. The degraded area was probed by scanning photoelectron microscopy (SPEM) using synchrotron. SPEM showed that the degradation was accompanied by a local drift of indium tin oxide (anode) toward Al (cathode) and that the heat from the degraded area separated the cathode from the Alq(3) layer, forming large bubbles. These results also indicate that microbubbles were formed under the Alq(3), implying, before popping, the existence of local high-temperature degradation spots.