High-Performance Eight-Membered Indacenodithiophene-Based Asymmetric A-D-A Type Non-Fullerene Acceptors

Indacenodithiophene (IDT) has been widely used as the central core to design high-performance acceptor-donor-acceptor (A-D-A)-type non-fullerene acceptors (NFAs). NFAs based on five-, six-, seven-, and nine-membered IDT have been successfully prepared. However, less research attention has been paid to the eight-membered IDT derivative. In this study, a novel asymmetric TTPTTT building block as an eight-membered IDT unit are designed and synthesized. The effect of nonfluorinated, monofluorinated, and difluorinated end-capping groups on the photovoltaic performance of TTPTTT-based NFAs are specifically investigated. By blending with the polymer donor PBT1-C, organic solar cells (OSCs) based on TTPTTT-IC, TTPTTT-2F, and TTPTTT-4F exhibited power conversion efficiencies (PCEs) of 7.91, 11.52, and 12.05%, respectively. Our results indicate that the asymmetric TTPTTT building block as an eight-membered IDT derivative is a promising central core unit for designing high-performance A-D-A type NFAs.