We report on the effects of surface-modified TiO2 on the open-circuit voltage (V-oc) of dye-sensitized solar cells (DSSCs). The TiO2 films were immersed into an aqueous zinc sulfate (ZS) solution to give ZS-modified photoelectrodes. The DSSCs with ZS-modified photoelectrodes showed a considerable improvement in V-oc, compared to that of the control device with pristine TiO2 layer. By monitoring open-circuit voltage decay, electrochemical impedance and dark current, it was revealed that the modification of the TiO2 surface by ZS led to a longer electron lifetime due to a reduction of interfacial charge recombination between photo-injected electrons and I-3(-) ions, and thereby inducing the increase in V-oc.