Donor–Acceptor Alternating Copolymer Nanowires for Highly Efficient Organic Solar Cells

A donor–acceptor conjugated copolymer enables the formation of nanowire systems that can be successfully introduced into bulk‐heterojunction organic solar cells. A simple binary solvent mixture that makes polarity control possible allows kinetic control over the self‐assembly of the crystalline polymer into a nanowire structure during the film‐forming process. The enhanced photoconductivity of the nanowire‐embedded photoactive layer efficiently facilitates photon harvesting in the solar cells. The resultant maximum power conversion efficiency is 8.2% in a conventional single‐cell structure, revealing a 60% higher performance than in devices without nanowires.