Fully phenylated C60Ph6 has never been synthesized in the past two decades largely due to steric effect and poor thermodynamic stability of the initial intermediate towards its isostructural penta-phenyl adduct (C60Ph5X) that has one central site intact. Herein, we report a kinetic management strategy using nitrobenzene that can efficiently alleviate the steric effect in the substitution reaction of C60Cl6 to synthesize C60Ph6. As revealed by X-ray crystallography, the molecule of C60Ph6, in stark contrast to its isostructural C60Ph5Cl with the last chlorine intact, shows a favorable geometrical structure and molecular stacking for electron transport. Furthermore, C60Ph6 shows high LUMO energy of −3.51 eV (0.4 eV higher than that of [6,6]-phenyl-C61-butyric acid methyl ester, PCBM), which is promising high open-circuit voltage for organic solar cells. The merits of both molecular packing and electrochemical property of C60Ph6 lead to high open-circuit voltage of 1.04 V for the OSC device based on poly(3-hexylthiophene) (P3HT). The present C60Ph6 exemplifies a novel class of electronic acceptors with fully aromatized groups on a fullerene cage.
