It is well known that TiO₂ nanoparticles have strong adsorption capacities of metal ions. In this study, the metal-ion-adsorbing ability of TiO₂ was utilized to reduce the dye adsorption time in the manufacturing process of solar cells. To incorporate the metal ions on the TiO₂ surface, the bare TiO₂/FTO was soaked in an aqueous solution of metal salt, then rinsed with water and dried. When the positively charged TiO₂ layer was dipped into dye solution, it could attract negatively charged dyes by electrostatic interaction. Thus, we could reduce the dye-adsorption time without declining the power conversion efficiency of solar cells.