Photodegradation of the organic/metal cathode interface in organic light-emitting devices

摘要

We study the photostability of organic light-emitting devices (OLEDs). Irradiating OLEDs by external illumination is found to result in a gradual increase in driving voltage and decrease in electroluminescence (EL) efficiency. This photoinduced degradation in device performance is found to be caused by changes at the organic/metal cathode interface that lead to a deterioration in electron injection. Evidence of photodegradation of the same interface, inherently, by device own EL, is also reported. The results uncover an important degradation mechanism in OLEDs and shed the light on a phenomenon that might limit the stability of other organic optoelectronic and photovoltaic devices.