Aggregation-Induced Emission Molecular Design for Mitigating Non-Radiative Energy Loss in Organic Solar Cells

Non-radiative energy loss remains a critical bottleneck limiting the open-circuit voltage (V_OC) and efficiency of organic solar cells (OSCs). Here, we introduce a molecular design strategy that leverages aggregation-induced emission (AIE) to suppress aggregation-caused quenching and enhance solid-state photoluminescence quantum yield (PLQY), thereby mitigating non-radiative recombination. A prototypical AIE motif, tetraphenylethylene, was incorporated into the terminal group of a Y-series non-fullerene acceptor to yield dTPE, which exhibits distinct AIE characteristics not previously observed in high-performance Y-series acceptors. Photoluminescence studies reveal that dTPE achieves a threefold enhancement in PLQY compared to L8BO-C4 in the film, leading to an electroluminescence external quantum efficiency more than an order of magnitude higher than that of D18:L8BO-C4. Consequently, the binary D18:dTPE device achieves a remarkably low non-radiative recombination loss of 0.130 eV. When incorporated as a guest into D18:L8BO-C4 blends, dTPE enables a non-radiative voltage loss of only 0.190 eV and an unprecedented V_OC of 0.93 V, yielding an efficiency of 20.5%. To our knowledge, this represents the highest V_OC reported for OSCs with efficiencies above 20%. This work establishes AIE molecular design as an effective pathway to overcome intrinsic limitations of Y-series acceptors and provides guiding principles for mitigating non-radiative energy loss in next-generation OSCs.