A Dimer Acceptor with Intramolecular Non‐Covalent Interactions for Low Energy Loss, Highly Efficient and Stable Organic Solar Cells

The development of efficient and stable organic solar cells (OSCs) remains a significant challenge. In this study, a dimer acceptor, named DYF‐ThC4, is successfully designed by introducing two fluorine atoms into the terminal phenyl moiety adjacent to the thiophene‐based linker, thereby establishing intramolecular F…S non‐covalent interactions. This novel acceptor is incorporated as a third component into the D18:L8‐BO binary system. The similarity in the molecular backbone between DYF‐ThC4 and L8‐BO promotes the formation of an alloy phase, which enhances the crystallinity and charge transport within the ternary blend film. Consequently, this approach effectively suppresses charge recombination, leading to a significant reduction in non‐radiative energy loss (Δ E nr ). Additionally, DYF‐ThC4 exhibits low diffusivity, aiding in the suppression of molecular migration and maintaining morphological stability. As a result, the D18:L8‐BO:DYF‐ThC4‐based device achieves a remarkable power conversion efficiency (PCE) of 19.87%, with a reduced Δ E nr of 0.194 eV, and significantly enhances thermal stability. These findings underscore the effectiveness of incorporating non‐covalent interactions in the design of dimer acceptors, marking a significant contribution to the advancement of efficient and stable OSCs.