Top-gate-type ambipolar organic field-effect transistors with indium–tin oxide drain/source electrodes using polyfluorene derivatives

The characteristics of solution processed top-gate-type organic field-effect transistors (OFETs) with indium–tin oxide (ITO) drain/source electrodes using polyfluorene derivatives were investigated. An OFET with poly(9,9-dioctylfluorene) (F8) as an active layer, which contains only a fluorene backbone, exhibited ambipolar characteristics with hole and electron field-effect mobilities of approximately 10−3 cm2 V−1 s−1. All OFETs with fluorene derivatives exhibited ambipolar characteristics because the value of the work function of the ITO electrode is approximately in the middle between the highest occupied molecular orbital and lowest unoccupied molecular orbital levels of fluorene derivatives. Fluorene derivatives can conduct both holes and electrons. Ambipolar OFETs with F8 and a fluorene derivative doped in F8 can be applied to various color tunable light-emitting devices.