Failure modes in polymer-based light-emitting diodes

Polymeric electroluminescent devices are now being made that achieve lifetimes of several thousands of hours at room temperature, and are probably nearing commercial appearance. This article reviews what has been learned about how to achieve these lifetimes, and considers what must still be done in order to extend them. Degradation processes discussed include formation of non-emissive spots due to cathode reaction, photooxidation in air, anode reactions, shorts and current leakage due to film defects and ion migration in strong fields, and probable sources of the slow luminance decay that limits the lifetime of state-of-the-art devices.