Bias-stress induced instability of organic thin film transistors

We have investigated the stability of polythienylene vinylene field-effect transistors under gate bias stress. On time scales up to 1000 s and tempera tures up to 140 degrees C, we only observe reversible charge relaxation eff ects and no degradation. We show the time dependence of the threshold volta ge shift at different temperatures. Furthermore, we discuss the influence o f water and oxygen on the relaxation process.