Pentacene thin film transistors (TFTs) were fabricated by using poly(4-vinylphenol) as the gate insulator and pentacene as the organic semiconductor on polyethyleneterephthalate substrates. The TFTs were characterized and the following parameters were obtained: a mobility of 0.8 cm(2)/Vs +/- 0.2 cm(2)/Vs, an on/off current ratio of 10(6) and a subthreshold slope of 1.0 V/dec. Inverter circuits based on the organic TFTs exhibited transfer curves typical of inverters with gains of 9.7 and a little hysteresis, which is indicative of a small number of interface states. (c) 2005 Elsevier B.V. All rights reserved.