Simultaneous electroluminescence and photoluminescence aging studies of tris(8-hydroxyquinoline) aluminum-based organic light-emitting devices

Using experimental devices which do not show electroluminescence, we have previously found that photoluminescence of tris(8-hydroxyquinoline) aluminum (AlQ(3)), a widely used organic electroluminescent material, decreases under prolonged transport of holes. This leads to a conclusion that AlQ(3) cations are unstable, and to our proposal that the same mechanism is responsible for degradation of organic light-emitting devices (OLEDs) based on AlQ(3). In this communication, we broaden our studies to include simultaneous electroluminescence and photoluminescence measurements on OLEDs containing thin AlQ(3) as the emitter layer. Results show that the decrease in the electroluminescence efficiency is indeed associated with degradation of the AlQ(3) in the vicinity of the hole transport layer interface. (C) 2001 American Institute of Physics.