Increased mobility from regioregular poly(3-hexylthiophene) field-effect transistors

Relatively high mobilities, μ=0.2 cm2 V−1 s−1 in the accumulation mode and μ=0.17 cm2 V−1 s−1 in the depletion mode, are reported for regioregular poly(3-hexylthiophene) (RR-P3HT) in field-effect transistors (FETs). Significantly higher mobility is obtained from FETs in which the RR-P3HT film is applied by dip-coating to a thickness of only 20−40 Å. These observations suggest that structural order of the semiconducting polymer at the interface between the semiconducting polymer and the SiO2 gate insulator is of paramount importance for achieving high carrier mobility. Heat treatment under nitrogen at 160 °C for 3 min increases the on/off ratio of the FET.