Development of a new benzo(1,2-b:4,5-b')dithiophene-based copolymer with conjugated dithienylbenzothiadiazole-vinylene side chains for efficient solar cells.

A new benzodithiophene-based copolymer PTG1 with dithienylbenzothiadiazole-vinylene side chains exhibits excellent film-forming ability, a deep HOMO energy level, and a good miscibility with PC(71)BM. Bulk heterojunction polymer solar cells fabricated from PTG1 and PC(71)BM showed a promising power conversion efficiency over 4.0%.