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.