Orientation of organic semiconductor films on photoreactive polyimide films and its influence on field-effect transistor characteristics

In this study, we have investigated the effect of surface treatment on the orientation and mobility of pentacene by using a photoreactive polyimide film to modify the gate-insulator surfaces of organic field effect transistors (OFETs). Surface modification includes a photoreactive polyimide film, presenting a passivated interface on which the semiconductor can grow. This polyimide film can control of the orientation of semiconductor by using linearly polarized deep UV (LPDUV) irradiation. Fabricated OFETs include stacked structures of Ta ₂O₅ as the gate insulators and the photoreactive polyimide. Most of the characteristic parameters of the OFETs, such as carrier mobility and on/off current ration, have been improved by using the photo-alignment treatment achieved with LPDUV irradiation.