Aggregation‐Induced Emission Molecular Design for Mitigating Non‐Radiative Energy Loss in Organic Solar Cells
Yingze Zhang, Rongkun Zhou, Mingjie Rong, Xianghao Zeng, Ho Ming Ng, Ruijie Ma, Joshua Yuk Lin Lai, C.K. Li, Shuwei Qiu, Heng Liu, Hao Xia, Jean W. Zu, G L Zhang, Xinhui Lu, Zilong Zheng, J. Liu, He Yan, Sai Ho Pun, Gang Li
Abstract
ABSTRACT 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.