Two kinds of fullerene derivatives have been designed to examine the effect of the fullerene substituents on the structure and photoelectrochemical properties of fullerene clusters electrophoretically deposited on nanostructured SnO2 electrodes. The cluster sizes increase and the incident photon-to-current efficiencies decrease with introduction of large substituents into C-60. The trend for photocurrent generation efficiency as well as surface morphology on the electrode can be explained by the steric bulkiness around the C-60 molecules. A C-60 molecule with two alkoxy chains is suggested to give a bilayer vesicle structure, irrespective of the hydrophobic nature of both the C-60 and alkoxy chain moieties. Such information will be valuable for the design of photoactive molecules, which are fabricated onto electrode surfaces to exhibit high energy conversion efficiency.