Methanofullerenes, C₆₀(CH₂)n (n = 1, 2, 3), as Building Blocks for High-Performance Acceptors Used in Organic Solar Cells

Selective preparation of C60(CH2)n (n = 1, 2, 3) was realized via a "Bingel-decarboxylation" route. A 54π-electron derivative of C60(CH2)2, OQBMF, demonstrates an outstanding power conversion efficiency (PCE) of 6.43% (Voc = 0.95 V, Jsc = 9.67 mA cm(-2), FF = 70%) in fullerene:P3HT solar cells since the small CH2 addends lift up fullerene LUMO and increase Voc significantly without decreasing mobility significantly.