Temperature dependent charge transport in poly(3-hexylthiophene)-block polystyrene copolymer field-effect transistor

Electronic transport of regioregular poly(3-hexylthiophene)-block-poly styrene (rr-P3HT-b-PS) copolymer in field effect transistor (FET) geometry with different surface treatment and different temperature is investigated. The devices show p type behavior with a maximum saturation mobility of 6 × 10−3 cm2/V s and current on/off ratio of 2.6 × 104 in an OTS treated sample at room temperature, which is lower compared to the controlled P3HT sample of same molecular weight fabricated with the same surface treatment. The mobility measured at different temperatures (300–150 K) show thermally activated hopping type transport mechanism with gate bias dependent activation energy of 100–270 meV which is higher compared to the reported value of pristine P3HT FET. The higher activation energy in hopping behavior and lower mobility in this block copolymer is caused by insulating PS segments.