Regio-Specific Selenium Substitution in Non-Fullerene Acceptors for Efficient Organic Solar Cells

A set of isomeric ladder type non-fullerene acceptors (NFAs), SRID-4F and TRID-4F, was designed and synthesized to systematically investigate the structure- property relationship of selenium substitution on A-D-A type NFAs. It was found that regio-specific selenium substitution not only affects the optical and electrochemical properties but also changes the morphology of thin films. Photovoltaic devices based on SRID-4F showed a high power conversion efficiency of >13% when paired with polymeric donor PBDB-T-2F.