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

Abstract A novel isotropic fullerene‐hybridized fused‐ring electron acceptor, designated C 60 ‐Y, has been synthesized via a mild [4+2] Diels–Alder cycloaddition reaction with fullerene C 60 to enhance the performance of organic solar cells (OSCs). Comparative analysis shows that C 60 ‐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 C 60 ‐Y, similar to fullerene, facilitates efficient interface formation with donor polymers and improves charge mobility. As a result, incorporating C 60 ‐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 C 60 ‐Y hold great potential for advancing high‐efficiency OSCs by enhancing exciton dissociation, reducing energy losses, and improving charge mobility.