Improved performance of dye-sensitized solar cells: An TiO 2-nano-SiO 2 hybrid photoanode with post-treatment of TiCl 4 aqueous solution

A TiO 2-nano-SiO 2 hybrid film was prepared on a conductive F-doped tin oxide (FTO) substrate by depositing a mixture paste of TiO 2 (P 25) and nano-sized SiO 2 particles. The hybrid film was further treated by a titanium tetrachloride (TiCl 4) 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 TiCl 4 could enhance the dye adsorption. The thin TiO 2 layer hydrolyzed from TiCl 4 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 75 mM for the post-treatment of TiO 2-SiO 2 hybrid film by TiCl 4 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 TiO 2 sensitized sample. TiO 2-nano-SiO 2 hybrid photoanode was prepared by incorporation of nano-sized SiO 2 in the TiO 2 film. The introduced SiO 2 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. © 2012 Elsevier B.V. All rights reserved.