High-temperature superconductivity in lattice-expanded C-60 (Retracted Article. See vol 298, pg 961, 2002)

C-60 single crystals have been intercalated with CHCl3 and CHBr3 in order to expand the lattice. High densities of electrons and holes have been induced by gate doping in a field-effect transistor geometry. At low temperatures, the material turns superconducting with a maximum transition temperature of 117 K in hole-doped C-60/CHBr3. The increasing spacing between the C-60 molecules follows the general trend of alkali metal-doped C-60 and suggests routes to even higher transition temperatures.