Surface modification of porous TiO2 electrode through pulse oxidative hydrolysis of TiCl3 as an efficient light harvesting photoanode for dye-sensitized solar cells

Abstract

A compact thin TiO2 layer suitable for I3−/I− electrolyte could be uniformly deposited along the pore walls in porous TiO2 film by pulse oxidative hydrolysis of TiCl3 solution. When applied the continuous anodic current, the TiO2 layer might be deposited at the entrance to the pores, leading to a decrease in the penetration of electrolyte into the pores of the porous TiO2 film. By tuning the pulse duty cycle and current density, the thin TiO2 layer could provide more active sites for adsorption of dye and improve the electrical contact between TiO2 nanoparticles. Moreover, the compact thin TiO2 layer could deposit on the exposed surface of fluoride-doped tin oxide substrate, giving rise to a suppression of charge recombination. Surface modification of porous TiO2 photoanode through pulse oxidative hydrolysis turned out to have positive effect on the photovoltaic characteristics of dye-sensitized solar cell (DSSC). DSSC with modified photoanode could significantly suppress the dark current density and increase the short-circuit current density in comparison to that with untreated photoanode. The energy conversion efficiency of DSSC was significantly enhanced from 7.12 to 8.47% when using the photoanode post-treated by pulse oxidative hydrolysis of TiCl3.