Failure mechanism of organic light emitting diodes (OLEDs) induced by hygrothermal effect

Organic Light Emitting Diodes (OLEDs) offer major potentials and advantages for the next generation of lightings and displays. Nonetheless, the degradation issues responsible for the short operation lifespan of the devices has yet to be fully established even with the invention of encapsulation layers. Hence, this paper presents the failure behavior of OLEDs induced by hygrothermal effect, specifically in non-operated mode (no current is supplied during conducted the test). In this study, a hygrothermal aging test was conducted on a batch of commercially fully-encapsulated OLEDs at 85 degrees C and 85% RH in a humidity chamber. The OLEDs were exposed to such extreme condition at the different time of exposure. Through an interlayer analysis by using Field Emission Scanning Electron Microscope (FESEM) equipment, two primary modes of failure were noticed within the failed sample. The first process involves the formation of centered-burst defects, and the second mode is the ring-shaped delamination of cathode film. Essentially, both failure modes have destroyed the entire aluminum film and permanently changed the morphological surface of the device which has led to the total failure of the device.