Improving Microstructured TiO2 Photoanodes for Dye Sensitized Solar Cells by Simple Surface Treatment

TiCl4 surface treatment studies of porous electrode structure of TiO2 aggregates synthesized using an acidic precursor and CTAB as a templating agent are carried out in order to understand and improve upon recombination kinetics in the photonanode fi lm matrix, together with enhancing the intrinsic light scattering. The key benefi cial features of the photoanode included high surface roughness, necessary for superior dye adsorption, nanocrystallite aggregates leading to diffuse light scattering within the fi lm matrix, and a hierarchical macro-and mesopore structure allowing good access of electrolyte to the dye, thereby assisting in dye regeneration (enhanced charge transfer). Pre-treatment of the TiO2 electrodes reduced recombination at the fl uorine-doped tin oxide (FTO)/electrolyte interface. The post-treatment study showed enhanced surface roughness through the deposition of a thin overlayer of amorphous TiO2 on the fi lm structure. This led to a notable improvement in both dye adsorption and inherent light scattering effects by the TiO2 aggregates, resulting in enhanced energy harvesting. The thin TiO2 overlayer also acted as a barrier in a core-shell confi guration within the porous TiO2 matrix, and thereby reduced recombination. This allowed the hierarchical macro-and mesoporosity of the fi lm matrix to be utilized more effectively for enhanced charge transfer during dye regeneration. Post-treatment of the aggregated TiO2 matrix resulted in a 36% enhancement in power conversion efficiency from 4.41% of untreated cells to 6.01%.