Effects of Moisture on Pentacene Thin-Film Transistors with Polyvinylpyrrolidone Gate Insulator

We report the effects of ambient moisture on the electrical characteristics of pentacenebased thin-film transistors (TFTs) with polyvinylpyrrolidone (PVPy) as a gate insulator. For the condition of relative humidity below 40%, pentacene TFT exhibited a stable operation without a shift in the threshold voltage upon a gate voltage sweep direction. However, the degradation in field-effect mobility and subthreshold slope critically occurred with increasing the relative humidity. Furthermore, the threshold voltage shifted toward the positive direction upon a gate voltage sweep direction. These characteristic degradations under the influence of moisture can be explained by charge-trapping of absorbed polar H2O molecules at the pentacene/PVPy interface.