Polydisperse ZnO spheres consisting of similar to 43-nm-sized nanoparticles are facilely synthesized for dye-sensitized solar cells. A uniform TiO2-coating layer on the ZnO surface improves both the open-circuit voltage and short-circuit current, and the power-conversion efficiency is consequently enhanced by a factor of approximately three. A thin coating layer suppresses the formation of Zn2+/dye complexes due to the enhanced chemical stability against the acidic dye, and also reduces charge recombination at the ZnO/dye/electrolyte interface. (C) 2013 Elsevier B.V. All rights reserved.