Trifluoromethyl‐Substituted Conjugated Random Terpolymers Enable High‐Performance Small and Large‐Area Organic Solar Cells Using Halogen‐Free Solvent

The advancement of non‐fullerene acceptors with crescent‐shaped geometry has led to the need for polymer donor improvements. Additionally, there is potential to enhance the photovoltaic parameters in high‐efficiency organic solar cells (OSCs). The random copolymerization method is a straightforward and effective strategy to further optimize photoactive morphology and enhance device performance. However, finding a suitable third component in terpolymers remains a crucial challenge. In this study, a series of terpolymer donors (PTF3, PTF5, PTF10, PTF20, and PTF50) is synthesized by introducing varying amounts of the trifluoromethyl‐substituted unit (CF3) into the PM6 polymer backbone. Even subtle changes in the CF3 content can significantly enhance all the photovoltaic parameters due to the optimized energy levels, molecular aggregation/miscibility, and bulk‐heterojunction morphology of the photoactive materials. Thus, the best binary OSC based on the PTF5:Y6‐BO achieves an outstanding power conversion efficiency (PCE) of 18.2% in the unit cell and a PCE of 11.6% in the sub‐module device (aperture size: 54.45 cm(2)), when using halogen‐free solvent o‐xylene. This work showcases the remarkable potential of the easily accessible CF3 unit as a key constituent in the construction of terpolymer donors in high‐performance OSCs.