An Investigation of Photocurrent Generation by Gold Electrodes Modified with Self-Assembled Monolayers of C60

Three different kinds of C60 alkanethiols have been prepared by changing systematically the linking positions, ortho, meta, and para, at a phenyl group on a pyrolidine ring fused to the C60 moiety. Electrochemical measurements showed that well-ordered structures are formed in self-assembled monolayers of these C60 alkanethiols on gold electrodes. Photoelectrochemical studies were carried out using gold electrodes modified with self-assembled monolayers of the C60. A stable anodic photocurrent was observed in the presence of an electron sacrificer when the modified gold electrode was illuminated with a monochromic light. Dependence of the photocurrents on the applied potential together with the agreement of the action spectra with the absorption spectra support the following photocurrent generation mechanism: the generation of a vectorial electron flow from the electron sacrificer to the gold electrode via the excited triplet state of the C60. The quantum yields vary from 7.5% to 9.8%, depending on the linking positions.