High Efficiency of Ternary Blend Organic Solar Cells with a BTP-4F/BTP-4H Derivative

Organic solar cells (OSCs) are renowned for their flexibility, cost-efficiency, and creative design options, yet persistent challenges drive ongoing research for improvement. One approach involves the replacement of fullerene acceptors with nonfullerene acceptors (NFAs) to address issues related to narrow absorption bands and low oxidation stability stemming from structural limitations. Another strategy tackles the limited absorption range and energy losses associated with bulk heterojunction (BHJ) OSCs by introducing ternary blend. In our study, we harnessed NFAs and ternary blend to address these OSC shortcomings. We engineered a novel NFA, Y5-BT, by modifying the side chain and extending the conjugation in the end group of Y5. This tailored NFAs demonstrated promise in improving energy level charge transport when incorporated into the ternary OSC PM6/Y6/Y5-BT, acting like an alloy-like model. In our optimized PM6/Y6/Y5-BT device, we achieved an open-circuit voltage (VOC) = 0.873 V, a short-circuit current density (JSC) = 27.2 mA cm-2, a fill factor (FF) = 73.5%, and a power conversion efficiency (PCE) = 17.6%.