A doped fullerene-based conductive material can be used as an electrode, which can contact a dielectric such as a high k dielectric. By aligning the dielectric with the band gap of the doped fullerene-based electrode, e.g., the conduction band minimum of the dielectric falls into one of the band gaps of the doped fullerene-based material, thermionic leakage through the dielectric can be reduced, since the excited electrons or holes in the electrode would need higher thermal excitation energy to overcome the band gap before passing through the dielectric layer.