Efficient polymer solar cells based on a broad bandgap D–A copolymer of “zigzag” naphthodithiophene and thieno[3,4-c]pyrrole-4,6-dione

A promising broad bandgap copolymer, PzNDTTPD, based on a rigid planar “zigzag” naphthodithiophene unit, was designed and synthesized. The BHJ solar cells based on PzNDTTPD:PC71BM blends afforded a power conversion efficiency of 5.3% with a high Voc over 0.9 V.