Enhanced Energy Conversion Efficiency of La3+-Modified Nanoporous TiO2 Electrode Sensitized with a Ruthenium Complex

The nature of TiO2 films and sensitizer play significant roles in determining the overall efficiency and mechanical stability of dye sensitized solar cell. In this study, cis-RuL2(SCN)(2), (L=2,2'-dipyridine-4,4'-dicarboxlic acid) was synthesized from 4-methylpyridine by the procedure of cross-coupling, oxidation, conjugation and ligand substitution. Tio(2) films were obtained by blending P25 and Tio(2) sol. To increase the photoelectric properties of the thin TiO2 films, La(No-3)(3) with different concentrations (0.1%, 0.3%, 0.5% and 0.7%) were added into the sol. Both undoped and doped samples of the thin films were sensitized by cis-RuL2(SCN)2 and structurally characterized by X-ray diffraction, atomic force microscopy and X-ray photoelectron spectroscopy. In addition, the photoelectric properties of the Tio(2) electrodes were investigated. The results show that doping lanthanum ions made the grain size smaller and surface area larger. When the concentration dopant is 0.5%, the short circuit current and open circuit voltage of the TiO2 film reach maximum. The short circuit current increases 0.54 mA/cm(2) more than that of undoped film, and the open-circuit voltage increases 30.41 mV more than that of undoped film.