Similar Roles of Electrons and Holes in Luminescence Degradation of Organic Light-Emitting Devices

Intrinsic degradation in organic light-emitting devices (OLEDs), the dominating cause of the short device lifetime, continues to be a critical issue for wider commercial application. For many years, intrinsic degradation in tris(8-hydroxyquinoline) aluminum (AlQ 3 )-based OLEDs has been known to be caused by excessive hole injection into the AlQ 3 emissive layer, due largely to earlier observations that electrons and holes act differently in the devices. However, a further investigation here leads to the discovery that excessive electrons can also induce significant degradation of the AlQ 3 layer, similar to what has been established for holes. The new understanding of the degradation mechanism of OLEDs is instrumental in directing the efforts of developing stable devices.