Soluble and processable regioregular poly(3‐hexylthiophene) for thin film field‐effect transistor applications with high mobility

The electrical characteristics of field‐effect transistors using solution cast regioregular poly(3‐hexylthiophene) are discussed. We demonstrate that both high field‐effect mobilities (ca. 0.045 cm2/V s in the accumulation mode and 0.01 cm2/V s in the depletion mode), and relatively high on/off current ratios (greater than 103) can be achieved. We find that the film quality and field‐effect mobility are strongly dependent on the choice of solvents. In addition, treating a film with ammonia or heating to 100 °C under N2 can increase the on/off ratio without decreasing the mobility.