XPS study of aluminum coating on TiO2 anode of dye-sensitized solar cells

In this study, we demonstrated that the aluminum sec-butoxide solution dip treatment is effective in improving the solar cell efficiency of the dye-sensitized solar cells. By XPS analysis, we successfully illustrate the cause for efficiency improvement. At low dipping concentrations, the efficiency increases, which is due to the formation of the Al2O3 coating on the exposed TiO2 surface that reduces the surface recombination centers. At high dipping concentrations, the efficiency decreases, which is due to the formation of top Al(OH)3 aggregates. The best efficiency achieved at 0.0075 M is the result of optimization of the formation of Al2O3 coating while avoiding the formation of top Al(OH)3 aggregates.