Reducing energy loss by developing luminescent triphenylamine functionalized electron acceptor for high performance organic solar cells

The persistent challenge of high non-radiative recombination energy loss (ΔE_nr) remains a critical bottleneck in advancing the power conversion efficiency (PCE) of organic solar cells (OSCs). Herein, a fused non-fullerene acceptor Z-Tri has been designed and synthesized by introducing a highly luminescent triphenylamine functional unit into the terminal group. Remarkably, the PM6:Z-Tri binary system achieves a low ΔE_nr of 0.137 eV, contributing to the reduction of ΔE_nr. Expanding upon this achievement, Z-Tri is judiciously incorporated as a guest component into the PM6:L8-BO blend, and the ternary OSC based on PM6:L8-BO:Z-Tri achieves an outstanding PCE of 20.32%, accompanied by a low ΔE_nr of 0.196 eV and an extraordinary open-circuit voltage (V_oc) of 0.927 V. Interestingly, a comprehensive analysis of both theoretical and experimental results demonstrates that an unprecedented mixed acceptor phase has formed between the two acceptors in the PM6:L8-BO:Z-Tri blend film, leading to lower aggregation-caused quenching (ACQ) and a superior photoluminescence quantum yield (PLQY), which heralds a revolutionary approach to suppressing ΔE_nr. This work underscores the significance of enhancing the luminescence properties of acceptor materials and optimizing their blending phases for developing high-efficiency OSCs.