Benzothiadiazole based conjugated polymers for high performance polymer solar cells

Three novel copolymers P1-3 with alkylthiophenyl substituted benzodithiophene as the donor unit, thiophene as the spacer, and benzothiadiazole as the acceptor unit have been designed, synthesized, and used as donor materials for polymer solar cells. Polymer solar cells with P3:PC71BM blends as the active layer exhibited a high power conversion efficiency (PCE) of 7.7% and a good tolerance to the change of film thickness. PCE higher than 7.3% can be obtained with the thickness of the active layer ranging from 90 to 380 nm, indicating that P3 is a very promising donor material for practical application.