Dilution effect induced aggregation-breaking via non-fused acceptors to suppress recombination in organic solar cell

Non-radiative voltage losses, primarily caused by Auger recombination and trap-assisted recombination in bulk heterojunctions, represent the key bottleneck limiting further improvement of the power conversion efficiency (PCE) in organic solar cells (OSCs). Herein, we proposed an aggregation-breaking strategy through halogenated non-fused ring acceptor (NFRA) based dilution effects to suppress the non-radiative recombination. In the PM6:L8-BO model system, the NFRA-mediated phase dilution exerts dual effects: (i) suppressing photoluminescence quantum yield (PLQY) quenching in L8-BO through aggregation-breaking mechanism, and (ii) generating smaller yet more ordered nanoscale domain that collectively mitigate trap-assisted recombination, ultimately enhancing electroluminescence quantum efficiency via reduced non-radiative losses in ternary devices. Encouragingly, this NFRA-dilution effects empowered device achieves a remarkable PCE of 20.25 % with an open-circuit voltage of 0.904 V. This work demonstrates the significance of the NFRA-triggered dilution effect to mitigate non-radiative voltage losses in high-performance OSCs.