Structure control of nanocrystalline TiO₂ for the dye-sensitized solar cell application

Controlling the nanocrystalline structure of TiO₂ powders is very important for the application to dye-sensitized solar cells (DSSC) because the efficiency of DSSC is considerably influenced on the change of the TiO ₂ nanostructures. Nanocrystalline TiO₂ powders were synthesized by the conventional sol-gel method, in which titanium iso-propoxide was reacted under various acid conditions. As-prepared TiO₂ powders were calcined at 600 °C for 5 h. The structural informations of the calcined TiO₂ powders were in detail characterized by X-ray diffraction, nitrogen adsorption isotherm, and electron microscopy. The structural analysis of as-prepared TiO₂ powders supported that their crystal structures were changed by the variation of acid solutions. In order to study the structural variations of the TiO₂ powders, some acid solutions were prepared with the selected mixtures of H₂SO₄, HCl, and HNO₃. The nanocrystalline properties such as crystal type and porosity were mainly affected by the use and the amount of H₂SO ₄.