Nanociystalline titanium oxide films were prepared by DC magnetron sputtering onto SnO2:F-coated glass substrates kept at temperatures in the 50 < τs < 300 °C range. Dye sensitization in cis-dithiocyanato-bis(2,2′-bipyridyl-4,4′-dicarboxylate) ruthenium(II) yielded solar cells with a conversion efficiency ?/. The dye incorporation was dependent upon τs, and an optimum value of η = 1.7% was found with ∼0.8-μm-thick titanium oxide films prepared at 250 °C. The microstructure then displayed a well-defined parallel penniform pattern, and the luminous transmittance was 42%. The crystallite size was substantially enlarged at τs > 250 °C, and η showed an ensuing decrease. © 2000 American Chemical Society.