Green Solvent-ProcessableTrifluoromethylated π‑ExtendedNon-Fullerene Acceptors for High-Efficiency Organic Solar Cells

Organic solar cells (OSCs) based on nonfullerene acceptors (NFAs) are promising for next-generation solar energy harvesting. However, their widespread adoption is hindered by the use of environmentally harmful halogenated solvents in processing. Here, we report a trifluoromethylated π-extended NFA, <b>BT-BO-CF</b>_<b>3</b>, that offers both high performance and excellent processability in environmentally friendly solvents. The trifluoromethyl groups and extended π-system provide a narrow bandgap for increased photocurrent while enhancing solubility in the green solvent tetrahydrofuran (THF). Importantly, <b>BT-BO-CF</b>_<b>3</b> exhibits superior cosolubility with the donor polymer <b>PTQ10</b> in THF, resulting in an excellent bulk heterojunction morphology without any additives. These inverted binary <b>PTQ10:BT-BO-CF</b>_<b>3</b> OSCs yield a power conversion efficiency (PCE) of 14.05% when processed from THF, dramatically outperforming the nonfluorinated <b>BT-BO</b> counterpart (PCE = 3.57%), and with only a ≈15% of PCE reduction versus a conventional <b>D18:BT-BO-CF</b>_<b>3</b> OSC processed in chloroform (PCE = 16.55%). Detailed characterization reveals that trifluoromethylation enhances intermolecular interactions, charge transport, and morphology in the active layer. This work demonstrates that strategic molecular design can simultaneously achieve performance while addressing processability challenges in OSCs, paving the way for more environmentally friendly manufacturing of high-efficiency devices.