Preparation Of Nanocrystalline Titanium Dioxide And Their Application In Dye-Sensitized Solar Cell

This thesis is about the the method through which to synthesize TiO2nanocrystallites with different morphologies and their applications in DSSC(dye-sensitized solar cells).1) We prepared TiO2spheres through two steps, using tetrabutyl titanate as precursor and ethanol as solvent. The first step was hydrolysis process and the second step was hydrothermal process. The diameter of TiO2spheres was about700-900nm. TiO2nanorods and flowers were synthesized by adding tetramethyl ammonium hydroxide (TMAH) through the same method. The diameter of TiO2nanorods was about50-100nm with the length ranging from250nm to800nm.Submicrometer sized TiO2flower were synthesized in this thesis and the diameter of flowers was about1000nm. The XRD patterns of TiO2spheres and rods showed that both of them were anatase phase. The XRD patterns of TiO2 flowers showed that flowers were mainly anatase phase with little portion of rutile.2) The light scattering of TiO2films with thickness of ca.3μm were evaluated. We found that both TiO2flower and sphere films showed larger reflectance than nanoparticle flim, which was due to their large size.In particularly, for TiO2flower flim,nearly complete reflectance was observed at short wavelength.3) We investigated the photovoltaic performances of TiO2photoanodes in this research. DSSC fabricated with sphere film electrode had a photoelectrical conversion efficiency of7.11%in this research. The photoelectrical conversion efficiency of DSSC based on pure flower film electrode was low while flower/sphere film were used in this paper,which finally had a photoelectrical conversion efficiency of7.62%. Comparing with TiO2spheres, TiO2nanorod films showed more faster electron transfer. We found that the electron transfer was faster withl longer nanorods.4)Photovoltaic performances of both flower/sphere and sphere films based DSSC with solid state electrolyte were evaluated. The flower/sphere and sphere showed higher conversion efficiency than that of the nanoparticle. The result showed that the flower/sphere DSSC was more efficient than the sphere one, ascribed to their large space voids and light scattering.