Simple Tricyclic-Based A-π-D-π-A-Type Nonfullerene Acceptors for High-Efficiency Organic Solar Cells.

Nonfused-ring electron acceptors have attracted much attention in recent years due to their advantages of simple synthetic routes, high yields, low costs, reasonable power conversion efficiencies (PCEs), and so on. Herein, three simple A-π-D-π-A-type acceptors ( DTC-BO-4F , DTS-BO-4F , and DTP-BO-4F ) comprising a tricyclic fused-ring core, two 2,5-bis(alkyloxy)phenylene spacers, and two difluorinated terminal groups (DF-IC) were developed. Compared with DTS-BO-4F , DTC-BO-4F and DTP-BO-4F exhibit higher molar extinction coefficients, stronger crystallinity, and more orderly stacking. The PBDB-T: DTC-BO-4F -based blend film shows suitable phase separation and higher and more balanced charge mobilities. Finally, the photovoltaic devices based on DTC-BO-4F give an outstanding PCE of 13.26% with a small nonradiative voltage loss of 0.23 eV.