Nanoporous ZnO electrodes, dye-sensitized with a ruthenium bipyridyl complex, were used as photoanodes in photoelectrochem. solar cells. By improving the interfacial contact between dyes and ZnO particles in the film, overall solar-to-elec. energy conversion efficiencies of up to 5% were obtained. The solar cell performance was studied as a function of film thickness, residence time of the electrodes in the dye soln., electrolyte compn., and light intensity.