N-channel operation of pentacene thin-film transistors with ultrathin polymer gate buffer layer

N-channel operation of pentacene thin-film transistors with ultrathin poly(methyl methacrylate) (PMMA) gate buffer layer and gold source–drain electrode was observed. We prepared pentacene thin-film transistors with an 8-nm thick PMMA buffer layer on SiO2 gate insulators and obtained electron and hole field-effect mobilities of 5.3 × 10−2 cm2/(V s) and 0.21 cm2/(V s), respectively, in a vacuum of 0.1 Pa. In spite of using gold electrodes with a high work function, the electron mobility was considerably improved in comparison with previous studies, because the ultrathin PMMA film could decrease electron traps on SiO2 surfaces, and enhance the electron accumulation by applied gate voltages.