This review article describes design of fullerene derivatives having high lowest unoccupied molecular orbital (LUMO) levels to obtain high open-circuit voltage in organic thin-film photovoltaic cells. Introduction of organic electron-donating groups onto fullerene and reduction of the size of π-electron conjugated system of fullerene effectively raise fullerene’s LUMO levels, affording high performance organic photovoltaic devices. Addition of the dihydromethano group as the smallest carbon addend to fullerene to obtain 56π-electron fullerene derivatives is likely a promising strategy in this research.