Effect of Annealing Temperature on the Photoelectrochemical Properties of Dye-Sensitized Solar Cells Made with Mesoporous TiO2 Nanoparticles

Mesoporous TiO2 (m-TiO2) nanoparticles were used to prepare the porous film electrodes for the dye-sensitized solar cells (DSSCs). The obtained m-TiO2 porous electrodes were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), electrochemical impedance spectra (EIS), and open-circuit photovoltage decay curves (OCVD). Experimental results indicate that the effect of bulk traps and the surface states within the m-TiO2 porous films on the recombination processes of the photoinjected electrons in DSSCs depends on the annealing temperature. Moreover, the homemade m-TiO2 nanoparticles show much higher photoelectric conversion efficiency than the nonporous TiO2 nanoparticles (P25). The mesostructures within the m-TiO2 nanoparticles, which can be maintained even after annealing at 500 °C, are of great benefit to the dye adsorption, and then to the improvement of the photoelectrochemical properties of DSSCs.