Improved performance of dye-sensitized solar cells: An TiO2–nano-SiO2 hybrid photoanode with post-treatment of TiCl4 aqueous solution

Abstract

A TiO2–nano-SiO2 hybrid film was prepared on a conductive F-doped tin oxide (FTO) substrate by depositing a mixture paste of TiO2 (P25) and nano-sized SiO2 particles. The hybrid film was further treated by a titanium tetrachloride (TiCl4) aqueous solution with different concentrations before it was assembled as a photoanode in dye sensitized solar cells (DSSCs). We studied the performance of DSSCs by using the dye molecule of cis-bis(isothiocy-anato)-bis-(2,2′-bipyridyl-4,4′-dicarboxylato)-ruthenium(II) bis-tetrabutylammonium (N719) as sensitizer. Results suggested that the post-treatment using TiCl4 could enhance the dye adsorption. The thin TiO2 layer hydrolyzed from TiCl4 could fill gaps between nanoparticles in the composite film, leading to a better electron transport than non-treated films, and improve the light harvesting efficiency. The optimal concentration was found to be 75mM for the post-treatment of TiO2–SiO2 hybrid film by TiCl4 solution. A photoelectron conversion efficiency of 6.39% was achieved in the back-side illuminated dye-sensitized solar cells, which is ∼105% higher than the basic efficiency of the bare TiO2 sensitized sample. TiO2–nano-SiO2 hybrid photoanode was prepared by incorporation of nano-sized SiO2 in the TiO2 film. The introduced SiO2 as a wide band-gap material gives a significant improvement of the performance of corresponding DSSCs in terms of photocurrent densities and energy conversion efficiency.