D–A copolymers with the benzo[1,2-b:4,5-c′]dithiophene-4,8-dione acceptor unit for polymer solar cells

Abstract

Two D–A copolymers PThBDTD and PTTBDTD with benzo[1,2-b:4,5-c′]dithiophene-4,8-dione (BDTD) as the acceptor unit and thiophene or thieno[3,2-b]thiophene as the donor unit were developed. They have medium optical bandgaps, deep HOMO levels, broad absorption and good hole mobilities. PThBDTD:PC₇₁BM and PTTBDTD:PC₇₁BM solar cells gave power conversion efficiencies (PCEs) of 6.32% and 6.00%, respectively.