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.

► We investigated the role of the block copolymers in charge transport of P3HT-b-PS FET. ► The P3HT-b-PS FET mobility at 300 K is much lower than the control P3HT FET. ► The temperature dependent mobility show hopping with activation energy Ea = 100 meV. ► This is much higher compared to the reported Ea = 60 meV value of pristine P3HT. ► Our results suggest that the PS segment create more disorder for charge conduction.