Synthesis and Characterization of a highly crystalline benzotriazole-selenophene copolymer semiconductor

Abstract A new donor (D)-acceptor (A) type copolymer semiconductor based on benzotriazole and selenophene was designed and synthesized. The benzotriazole-selenophene copolymer (P(BTz-Se)) showed a highly crystalline lamellar packing structure with a lamellar interchain distance of 1.77 nm and large mean crystalline domain size of 17.26 nm. The average field-effect hole mobility of an as-cast P(BTz-Se) film was 2.93 × 10−4 cm2 V−1 s−1. After annealing the polymer film at 150 °C, a 55-fold enhanced average hole mobility (1.61 × 10−2 cm2 V−1 s−1) with high on/off current ratio (1.7 × 106) was observed. In addition to the great charge carrier mobility, P(BTz-Se) showed a narrow energy bandgap (1.69 eV) and broad optical absorption range with excellent absorption coefficient, suggesting that this copolymer semiconductor may also be a good electron donor in organic photovoltaic devices.