5.1: Invited Paper: Degradation Analysis of Light Emitting Diodes by Time Resolved Photoluminescence Measurements.

We demonstrate that the degradation in Alq₃-based OLEDs is caused by the photophysical degradation processes of α-NPD and Alq₃ molecules in the vicinity of the α-NPD/Alq₃ interface. Two degradation pathways with different time constants take place during a decrease in electroluminescence under constant current operation. From time resolved photoluminescence measurements, we identify the first stage of the degradation is due to the decomposition of α-NPD molecules via the singlet excited states formed by recombining charge carriers. The second stage of the degradation is attributed to the formation of a luminescent quencher originated from the reaction of excited state of Alq₃. [ABSTRACT FROM AUTHOR]