Isomerism Effect of 3D Dimeric Acceptors for Non‐Halogenated Solvent‐Processed Organic Solar Cells with 20 % Efficiency

Organic photovoltaic materials that can be processed via non-halogenated solvents are crucial for the large-area manufacturing of organic solar cells (OSCs). However, the limited available of electron acceptors with adequate solubility and favorable molecular packing presents a challenge in achieving efficient non-halogenated solvent-processed OSCs. Herein, inspired by the three-dimensional dimeric acceptor CH8-4, we employed a molecular isomerization strategy to synthesize its isomers, CH8-4A and CH8-4B, by tuning the position of fluorine (F) atom in the central unit. The differing intramolecular fluorine-sulfur non-covalent interactions among these isomers led to differences in molecular pre-aggregation abilities (CH8-4B2). Our findings underscore the potential of isomerism in 3D dimer acceptors to enhance the performance of eco-friendly OSCs.