Novel Dimethylmethylene‐Bridged Triphenylamine‐PDI Acceptor for Bulk‐Heterojunction Organic Solar Cells

A novel, star‐shaped electron acceptor, DMTPA‐PDI(3), derived from a planar dimethylmethylene‐bridged triphenylamine core with three acetylene‐linked perylene diimide (PDI) units is developed as a nonfullerene acceptor for organic solar cells (OSCs). DMTPA‐PDI(3) manifests significantly reduced intramolecular twisting, enabling sufficient system‐wide π‐electron delocalization leading to broadened spectral absorption and raised lowest unoccupied molecular orbital level. As a result, higher and more balanced hole and electron transport properties are observed. Active layers for OSCs comprising DMTPA‐PDI(3) acceptor and PBT7‐Th donor exhibit suppressed intermolecular aggregation, giving rise to uniform nanophase network formation. These OSC devices have afforded respectably high power‐conversion efficiency of about 5%.