Influence of temperature and drive current on degradation mechanisms in organic light-emitting diodes

We measured luminance decay and half life for green organic light-emitting diodes composed of materials with high glass transition temperature. The devices were driven at dc, constant current density ranging from 3.8 to 130 mA/cm2 at 25, 85, and 120 °C. The shapes of the luminance decay curves were compared by redrawing the curves on a time scale normalized by each half life. Temperature and drive current shortened the half life. However, the normalized decay curve of the device driven at 120 °C had the same shape as that of the device driven at 25 °C. Drive current also left the shape of the decay curves unchanged. Therefore, we conclude that the temperature and drive current do not change the relative contribution of multiple degradation mechanisms.