Degradation Process in Pentacene-Based Organic Field-Effect Transistors Evaluated by Three-Terminal Capacitance-Voltage Measurements

ABSTRACTBy taking advantage of three-terminal capacitance-voltage (TT-CV) measurement, we investigated a formation of trapped charge in pentacene(Pn)-based organic field-effect transistors (OFETs) during the bias stress measurement. The shift of the turn-on voltage in transfer curve correlated well with the increase of trapped charge estimated from TT-CV curves. Moreover, TT-CV measurement revealed that the trapped charges were distributed inhomogeneously at the vicinity of the pentacene/insulator interface, indicating that the current does not obviously affect their formation. Thus we suggested that the trapped charges are formed by keeping Pn molecules as unstable cation (hole state) by the prolonged bias stress.