One of the strategies for designing high performance polymeric semiconductors is to incorporate heteroacenes into conjugated polymer backbone to enhance the coplanarity and thus the
intermolecular interaction. However, the solubility of CPs will decrease dramatically when large
heteroacenes are employed. To overcome this problem, we synthesized two new heteroacenes based
on carbazole unit, i.e. dithieno[2,3-b;7,6-b]carbazole (DTC1) and dithieno[3,2-b:6,7-b]carbazole
(DTC2), in which a alkyl chain can be introduced at N atom. Their copolymers with bithiophene,
diketopyrrolopyrrole (DPP) and thienopyrroledione (TPD) were synthesized by Stille coupling.
Bottom gate and top contact organic thin films transistors (OTFTs) and bulk heterojunction solar
cells (PSCs) were fabricated to study the effect of molecular structures on charge transporting and photovoltaic properties. The highest mobility of 1.36 cm2/V·s for OTFTs and power conversion
efficiency of 8.0% for PSCs have been demonstrated.
