Good solvent effects of C-70 cluster formations and their electron-transporting and photoelectrochemical properties have been systematically examined for the first time Nano-to-micrometer scale assemblies of C-70 with different morphologies were prepared by rapidly injecting poor solvent (i e, acetonitrile) into a solution of C-70 dissolved in various good solvents (i e, benzene, toluene, chlorobenzene etc) The cluster morphology engineering was successfully achieved by changing the good solvent, yielding the spherical rodlike or platelike clusters in the mixed solvents The clusters of C-70 were electrophoretically deposited onto a nanostructured SnO2 electrode to examine the photoelectrochemical properties under the white light or monochromatic light illumination The maximum incident photon-to-current efficiency (IPCE) varied from 08 to 10% depending on the combinations of the poor-good solvents I he differences in the IPCE values are discussed in terms of the surface area thickness and electron mobility of the deposited cluster films I he electron mobility is found to be the most predominant factor for the IPCE indicating the importance of the election-transporting process in the overall photocurrent generation In addition the electron mobility is closely correlated with the underlying molecular alignment and the resultant cluster structure Thus these results will provide basic clue for the design of C-70-based molecular devices including the organic photovoltaics