Mesoporous TiO2 films were modified with Sm(NO3)(3).6H(2)O and TiCl4 mixture solution in dye-sensitized solar cells. Samarium oxide was formed after modification according to UV-vis absorption spectra and X-ray photoelectron spectra (XPS) analyses, and acted as energy barrier on TiO2 surface. The electron recombination reaction with I-3- can be suppressed when samples are treated using Sm3+/TiCl4 solutions via electrochemical impedance spectroscopy (EIS) and open circuit voltage decay (OCVD) analyses. With the mesoporous TiO2 film modified by the TiCl4 mixture solution contained 0.07 M samarium trinitrate, the power conversion efficiency of the dye-sensitized solar cell is increased from 6.91% to 8.23%. The enhanced performance is ascribed to the increase of dye loading, the reduce of surface state density, and the energy barrier created on TiO(2)surface. It is a effective method to improve the power conversion efficiency without requiring a tedious synthesis pathway.