A benzodithiophene-thienothiophene derivative with cyano acrylate side chain: A novel donor polymer with deep HOMO level for p-n heterojunction solar cells

A new promising benzodithiophene and thienothiophene-based copolymer with cyano acrylate side chain, BDT8TT, has been designed and synthesized for efficient bulk heterojunction solar cells. The copolymer shows good solubility and film-forming ability combining with excellent thermal stability. Furthermore, BDT8TT displays a broad absorption in the near-IR region (from 300 to 1000 nm). Specially, this conjugated polymer exhibits quite high open circuit voltage by a highly deep-lying HOMO level at − 5.76 eV. Good power conversion efficiencies are demonstrated in solar cell studies; the polymer solar cell was fabricated from the blend of the polymer as a donor and PC71BM as an acceptor without annealing and any additives.