Tuneable single-molecule electronic conductance of C60 by encapsulation

Abstract

It has been demonstrated that the single-molecule transport properties of fullerene C₆₀ can be modulated by encapsulating endohedral species, i.e. Li⁺ and H₂O, which exhibit different degrees of van der Waals interactions with the C₆₀ cage. Single-molecule junctions were prepared between the gaps of Au electrodes using a break junction technique. Encapsulation of H₂O inside the cage caused a slight decrease in the electronic conductivity relative to that of pristine C₆₀. This is in sharp contrast to Li⁺ encapsulation, which results in a twofold-to-fourfold increase in the conductivity. The electronic couplings between the C₆₀ cage and the Au electrodes were weakly dependent on the endohedral species in the cage, though the molecular orbital energy levels were remarkably modulated upon encapsulation.