A direction to increasing photovoltaic performances of dye sensitized solar cells (DSC) is proposed. An interface between TiO2/dye and an electrolyte layer is focused on. It is proved that better coverage of TiO2 layers with dye molecules increases photovoltaic performances, where dye staining is carried out in pressurized CO2 atmosphere. This is explained by decreases in the amount of surface traps on TiO2 nano-particles, which is discussed by thermally stimulated current (TSC). The decrease in the surface trap density increases electron diffusion coefficient and improves electron lifetime in TiO2 layers. In addition, the TiO2-staining with dye molecules having the larger dipole moment seems to leave less amount of electron trap. Another crucial research item is solidification. Quasi-solidification is carried out by using surface modified anodically-oxidized Al2O3 films filled with ionic liquids, where ion paths are fabricated on the surface-modified Al2O3 walls by concentrating iodine and iodide molecules on the walls. Because of the fabrication of the ion path, photovoltaic performances increased even after solidification. Grötthuss type mechanism is introduced to explain the increase in the photovoltaic performances after the solidification.