Conformationally Locked Macrocyclic Acceptors with Enhanced Photoluminescence for High-Efficiency Organic Solar Cells.

Minimizing non-radiative recombination loss remains a critical challenge for advancing the efficiency of organic solar cells (OSCs). Herein, a molecular design strategy based on a series of cyclic π-conjugated electron acceptors is reported, RCM-C6, RCM-C5, and RCM-C4, to effectively suppress non-radiative loss pathways. Compared to their linear analogues, these cyclic molecules demonstrate a significantly enhanced photoluminescence quantum yield, exceeding 14%. This is achieved by effectively suppressing the high-frequency vibrational modes, minimizing non-radiative decay channels. Further, while cyclic molecules have historically suffered from unfavorable aggregation that impedes charge transport, this limitation has been overcome by systematically tuning the alkyl chain lengths on the RCM framework. This approach allows for precise control over molecular packing and optimization of thin-film morphology. As a result, a high-performance OSC is fabricated, achieving a power conversion efficiency of 17.1%, the highest reported for macrocycle-based systems to date. This work demonstrates that macrocycle conjugated architecture provides an instructive approach to suppress non-radiative recombination while maintaining efficient charge transport, establishing a new framework for rational design of next-generation high-performance organic photovoltaic materials.