C‐H Arylation‐Constructed Non‐Fully‐Fused Dimeric Acceptors for o ‐Xylene Processed Organic Solar Cells With 20.17% Efficiency

ABSTRACT Although organic solar cells (OSCs) have made significant progress in photovoltaic performance, their practical applications still face challenges, such as the complex material synthesis and involvement of Stille coupling reaction with organotin reagents of fused‐ring electron acceptors, and using halogenated toxic solvents in device fabrication. Here, we develop two non‐fully‐fused dimeric acceptors (named dNA‐C6 and dNA‐C12) with varying alkyl linker lengths using organotin‐free C‐H activation approach, which present the advantages of environmental friendliness and easy synthesis. When introducing dNA‐C6 and dNA‐C12 into PM6:BTP‐eC9 system, these OSCs achieve higher power conversion efficiencies (PCEs) of 19.07% and 18.74%, respectively, compared to their parental monomer based device (18.44%), while the dNA‐C6 based OSC obtains both superior PCE and device stability. Moreover, dNA‐C6 is also introduced into D18:BTP‐eC9 host to verify its universality in boosting photovoltaic performance, and the relevant device processed with halogen‐free o ‐xylene offers a further improved PCE of 20.17%, ranking among the highest values in the reported non‐fully‐conjugated dimeric acceptors and halogen‐free solvent processed OSCs. This work develops organotin‐free synthesized non‐fully‐fused dimeric acceptors by integrating eco‐friendly chemistry for preparing green solvent processed OSCs with high PCE and device stability.