Fine-tuning non-fullerene acceptors with halogenation and silicon incorporation for high-performance organic solar cells.

Three novel Y-series NFAs (HSi, FSi, ClSi) with 2D side chain modifications were synthesized to study effects on photovoltaic performance. Halogenation altered molecular packing and energy levels, impacting efficiency. HSi exhibits balanced crystallinity and stacking, resulting in a reduction of non-radiative energy loss to 0.172 eV, a maximum VOC of 0.940 V, and a PCE of 19.56%.