Potassium Salt Promoted Regioselective Three-Component Coupling Synthesis of 1,4-Asymmetrical [60]Fullerene Bisadducts with Superior Electron Transport Properties

Bisadducts of [60]fullerene (C60) show promising applications in organic photovoltaic devices, but conventional synthesis generally requires multisteps and generates multiple isomers. In this work, an efficient one-pot three-component domino coupling reaction of phenols, C60, and bromoalkanes was developed, resulting in the highly regioselective synthesis of 1,4-asymmetrical C60 bisadducts. The reaction utilizes the metal salt KOtBu as a promoter and likely proceeds by an oxyanion/carbanion rearrangement/nucleophilic addition cascade. The as-prepared 1,4-bisadducts of C60 were further applied as novel electron transport materials of perovskite solar cells, affording a high power conversion efficiency of 17.72%, which surpasses the one generated by the commonly used PCBM ETM.