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. A novel TTPTTT building block as an eight‐membered indacanodithiophene derivative is developed. The effect of nonfluorinated, momofluorinated, and difluorinated end‐capping group on photovoltaic performance of asymmtry TTPTTT non‐fullerene acceptors (NFAs) is investigated. As a result, organic solar cells based on TTPTTT‐4F exhibit a high efficiency of 12.05%, indicating that the asymmetric TTPTTT unit is a promising central core unit for designing efficient A‐D‐A type NFAs. [ABSTRACT FROM AUTHOR]