Fullerene‐Hybridized Fused‐Ring Electron Acceptor with High Dielectric Constant and Isotropic Charge Transport for Organic Solar Cells

A novel isotropic fullerene-hybridized fused-ring electron acceptor, designated C₆₀-Y, has been synthesized via a mild [4+2] Diels-Alder cycloaddition reaction with fullerene C₆₀ to enhance the performance of organic solar cells (OSCs). Comparative analysis shows that C₆₀-Y significantly outperforms the control acceptor Me-Y, with a notable increase in the relative dielectric constant from 2.79 to 3.95. This improvement enhances exciton dissociation and reduces non-radiative energy losses. Additionally, the isotropic molecular packing of C₆₀-Y, similar to fullerene, facilitates efficient interface formation with donor polymers and improves charge mobility. As a result, incorporating C₆₀-Y as an electron acceptor increases the power conversion efficiency (PCE) of binary OSCs to 15.02 %, surpassing the 13.31 % achieved with Me-Y. Moreover, when integrated into a ternary blend system, an impressive PCE of 19.22 % is achieved, top-performing among reported ternary OSCs utilizing fullerene derivatives as the third component. These results suggest that fullerene-hybridized acceptors like C₆₀-Y hold great potential for advancing high-efficiency OSCs by enhancing exciton dissociation, reducing energy losses, and improving charge mobility.