Titanium dioxide sols synthesized by hydrothermal methods using tetrabutyl titanate as starting material and the application in dye sensitized solar cells

TiO2 sols were synthesized via hydrothermal reaction using a less hydrolysable alkoxide or tetrabutyl titanate as the starting material. Using characterizations of X-ray diffraction, dynamic laser scattering and transmission electron microscopy, particle coarsening dynamics along with the particle dispersion behavior in the sols were studied via changing hydrothermal temperature from 160 °C to 250 °C. It was observed that, pure anatase phase was obtained in the whole examined temperature range. With temperature increasing, the particle size distribution in the sols first narrowed, and then broadened. Mono-dispersed nanocrystallites were obtained at the temperature of 220 °C. Aggregations were formed between the nanocrystallites at other temperatures. The causes of the aggregating behavior were analyzed and found to be different when the temperature was less than or beyond 220 °C. The as-synthesized TiO2 sols were used in fabrication of dye sensitized nanocrystallite solar cell. The cells assembled from temperature of 220 °C came out with the best photo-to-electric energy conversion efficiency, which is ascribed to the improved dispersion of particles in TiO2 sols.