Effects of concentration and annealing on the performance of regioregular poly(3-hexylthiophene) field-effect transistors

This paper investigates the effects of concentration on the crystalline structure,the morphology,and the charge carrier mobility of regioregular poly(3-hexylthiophene) (RR-P3HT) field-effect transistors (FETs).The RR-P3HT FETs with RR-P3HT as an active layer with different concentrations of RR-P3HT solution from 0.5 wt% to 2 wt% are prepared.The results indicate that the performance of RR-P3HT FETs improves drastically with the increase of RR-P3HT weight percentages in chloroform solution due to the formation of more microcrystalline lamellae and bigger nanoscale islands.It finds that the field-effect mobility of RR-P3HT FET with 2 wt% can reach 5.78×10 3 cm 2 /Vs which is higher by a factor of 13 than that with 0.5 wt%.Further,an appropriate thermal annealing is adopted to improve the performance of RR-P3HT FETs.The field-effect mobility of RR-P3HT FETs increases drastically to 0.09 cm 2 /Vs by thermal annealing at 150 C,and the value of on/off current ratio can reach 10 4.