It is necessary and challenging to achieve high-efficiency organic solar cells (OSCs) by suppressing nonradiative energy loss (Delta E-nr) and fine-tuning active layer morphology through the delicate active material design. In this study, we design two asymmetric acceptors, a-CH-ThCl and a-CH-Th2Cl, featuring asymmetric conjugated substitutions on central cores via single bond linkages. Single crystals analysis indicate that these two acceptors exhibit intense J-aggregation induced by the asymmetric substitution, which favours for their high photoluminescence quantum yields and contributes to reducing non-radiative recombination. Meanwhile, the two asymmetric acceptors demonstrate enhanced miscibility and optimized morphology with the donor D18. Consequently, the binary device based on D18: a-CH-Th2Cl demonstrates an impressive efficiency of up to 19.10 % with a high open-circuit voltage of 0.935 V, attributed to the remarkably low Delta E-nr of 0.179 eV and optimized morphology. These results provide an effective strategy for material design to optimize molecular packing, reduce non-radiative recombination and tune active layer morphology to achieve high-efficiency OSCs.