Hexacyclic lactam building blocks for highly efficient polymer solar cells

Abstract

Two hexacyclic lactam building blocks, TD1 and TD2, and four D–A copolymers have been developed. Compared with thiophene copolymers, selenophene analogues PSeTD1 and PSeTD2 possess medium optical bandgaps, better packing, higher hole mobilities, enhanced EQE, and higher J_sc. Inverted PSeTD2:PC₇₁BM solar cells exhibited a decent PCE of 8.18%, which is a record for D–A copolymers using selenophene as the donor unit.