Synthesis of New Thiadiazole-Containing Polythiophene Derivatives and Their Application to Organic Solar Cells

Abstract

New thiadiazole-containing π-conjugated polymers have been successfully synthesized by the Stille coupling reaction of 2,5-bis(5’-bromo-3’,4’-dihexylthien-2’-yl)-1,3,4-thiadiazole (1) with various distannyl compounds as acceptor and donor monomer units, respectively. Most of polymers showed lower highest occupied molecular orbital (HOMO) energy level than poly(3-hexylthiophene) (P3HT). It was found that the bulky side chains of donor units tend to prevent the arrangements of main chains. The polymer comprised of thienothiophene donor units without side chains displayed relatively high solar cell performance with a power conversion efficiency (PCE) of 2.8% under the illumination of AM 1.5, 100 mW/cm².