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 (AlQ3)-based OLEDs has been known to be caused by excessive hole injection into the AlQ3 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 AlQ3 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.