Poly(3,6-dihexyl-thieno[3,2-b]thiophene vinylene): Synthesis, Field-Effect Transistors, and Photovoltaic Properties

Poly(3,6-dihexyl-thieno[3,2-b]thiophene vinylene) (DH-PTTV) was prepared by the Pd-catalyzed Stille-coupling method. Compared with poly(3-hexylthienylene vinylene) (P3HTV), strong photoluminescence was observed for DH-PTTV solution, whereas the maximum absorption of DH-PTTV was blue-shifted. The solution-processed organic field-effect transistors (OFETs) were fabricated with bottom gate/top contact geometry. The highest FET hole mobility of DH-PTTV after thermal annealing at 180 degrees C for 30 min reached 0.032 cm(2)/V.s with all on/off ratio of 10(5), which is a high value for the conjugated polymers. Polymer solar cells based on the polymers were fabricated, and the power conversion efficiency of the devices based on P3HTV and DH-PTTV was 0.19 and 0.28%, respectively, under the illumination of AM 1.5 and 100 mW/cm(2). The efficiency of the device based on DH-PTTV is ca. 50% higher than that of the devices based on P3HTV, which could be benefited from the higher hole mobility of DH-PTTV.