TiO2 photoanode surface modification via combined action of samarium and titanium salt in dye-sensitized solar cells

•The TiO2 Photoanodes were treated Sm(NO3)3•6H2O and TiCl4 mixture solutions.•The PCE of DSSCs were 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 TiO2 surface.

Mesoporous TiO2 films were modified with Sm(NO3)3·6H2O 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 I3− 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 TiO2 surface. It is a effective method to improve the power conversion efficiency without requiring a tedious synthesis pathway.