An alternating D–A₁–D–A₂ copolymer containing two electron-deficient moieties for efficient polymer solar cells

Unlike normal donor–acceptor (D–A) polymers containing only one electron-deficient segment in their repeating unit, the incorporation of two electron-deficient moieties with different absorption behaviors, forming a D–A₁–D–A₂ internal structure in the alternating copolymer, showed a broader absorption spectrum than its constituent parts and enhanced photovoltaic performance. This work is anticipated to open the door to the design of new low bandgap polymers with a broader absorption range for efficient polymer solar cells.