Synthesis and Photovoltaic Properties of Conjugated Polymer Based on 1,3,4-Thiadiazole Unit

A novel conjugated polymer based on cyclopenta[2,1-b:3,4-b′]dithiophene and 1,3,4-thiadiazole with two electron-withdrawing imine (C=N) nitrogen atoms in a five-membered ring has been synthesized by the Stille coupling reaction. Optical band gap of the polymer estimated from the absorption edge was found to be 1.77 eV. The photovoltaic device consisting of the polymer and a fullerene derivative (PCBM) showed a power conversion efficiency of 1.06% under simulated AM 1.5G irradiation of 100 mW cm−2.