Influence of annealing temperature and organic dyes as sensitizers on sol-gel derived TiO2 films

Five different organic dyes and reported cocktail dye composed of these dyes are used as sensitizer for titanium dioxide (TiO2). Rice shaped (TiO2) nanorods are prepared by using sol-gel method. The films annealed at 673 K and above are crystalline with anatase structure. The effect of post annealing temperature is studied on various structural parameters. Cocktail dye shows broader absorption with TiO2 nanorods in visible region compared with five dyes. Maximum photosensitivity is obtained with RhB dye, followed by FGF and cocktail dye sensitized TiO2 films. Increase in photosensitivity is due to passivating some hole traps on the surface up to some optimum temperature, above which photosensitivity decreases due to a higher photo activation energy compared to dark conductivity in low temperature region and also may be due to damage of the dye molecule. This work may prove its worth for understanding the electron transport in dye sensitized nanodevices.