FAILURE MODES IN VAPOR-DEPOSITED ORGANIC LEDS

A study of the main failure mechanisms in vacuum vapor-deposited organ ic light-emitting diodes (LED's) is presented. Three degradation modes were identified for a prototype bilayer ITO/TPD/Alq(3)/Mg/Ag device: a) formation and growth of black nonemissive spots, b) abrupt ceasing of light emission associated with catastrophic failures caused by elec trical shorts, and c) long term wearout associated with the decrease o f quantum efficiency and luminance along with an increase in voltage, while the device is stressed under constant current.