In order to prevent the charge recombination at the interface between the transparent-conducting oxide (TCO) substrate and electrolyte, a TiO2 compact layer was deposited on the substrate by hydrolysis of TiCl4 aqueous solution. Optimum thickness of the compact layer was found to be similar to 25 nm, which showed similar to 24% increase in the power-conversion efficiency compared with the bare cell. Impedance spectra indicated that the interfacial charge-transfer resistance of TCO/electrolyte interface was increased by more than a factor of three with the TiO2 compact layer at 0.4 V. Moreover, the electron-carrier lifetime of the 25 nm-deposited cell was improved by a factor of five compared with the bare cell. (C) 2011 Elsevier B. V. All rights reserved.