Post-Treatment-Free Main Chain Donor and Side Chain Acceptor (D-s-A) Copolymer for Efficient Nonfullerene Solar Cells with a Small Voltage Loss.

Main chain donor and side chain acceptor (D-s-A) copolymers are an important branch of the D-A copolymer family. However, the development of D-s-A copolymers significantly falls behind the alternative D-A copolymers, especially for organic solar cells, because a breakthrough in device performance is not yet obtained with a reported power conversion efficiency (PCE) of 2%-4%. Herein, a newly developed D-s-A copolymer PDRCNBDT, bearing 2-(1, 1-dicyanomethylene) rhodanine pendant group as the donor material, delivers a high PCE of 5.