High-Efficiency Ternary Organic Solar Cells Based on the Synergized Polymeric and Small-Molecule Donors

Despite the impressive progress that has been achieved for organic solar cells (OSCs) in recent years, challenges remain for OSCs due to the presence of the trade-off between photovoltage and photocurrent that sets limitation on the performance enhancement of regular bulk heterojunction (BHJ) blends. Herein, a new small-molecule (SM) donor, BPR-SCl, with the deep-lying highest occupied molecular orbital and strong crystallinity has been developed, which, as the third component, is synergized with PM6:Y6 host blend. The introduction of BPR-SCl enhances molecular packing, exciton dissociation, as well as charge mobilities of ternary blends, yielding simultaneous enhancement of open-circuit voltage, short-circuit current density, and fill factor of ternary OSCs (TOSCs). As a result, an optimal power conversion efficiency (PCE) of 16.74% is obtained for TOSCs with 25 wt% BPR-SCl, accounting for 10% and 70% improvements over those of pristine PM6:Y6 and BPR-SCl:Y6 binary devices, respectively. Overall, herein, it is demonstrated that the design of SM donor as the third component is effective in achieving high-performance TOSCs.