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/cm(2) at 25, 85, and 120 degreesC. 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 degreesC had the same shape as that of the device driven at 25 degreesC. 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. (C) 2002 American Institute of Physics.