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Comparative XRD HREM and BET studies of nanocrystalline phases in calcinated sol-gel TiO2

Nanosized TiO2 plays an important role in new generation of solar cells. Dye-sensitized cells differ from conventional semiconductor devices in that they separate the function of light absorption from charge carrier transport. The device is based on a 10 micro-meters thick, optically transparent film of titanium dioxide grains, a few nanometers in size, coated with monolayer of charge-transfer dye to sensitize film for light harvesting. Comparative studies of nanocrystalline phases in TiO2 obtained by sol-gel method have been performed by X-ray diffraction (XRD), high resolution electron microscopy (HREM) and BET (Brunauer-Erett-Teller) adsorption of nitrogen gas at the temperature of liquid nitrogen for surface area determination. Using DTA/TGA analysis it was found that the temperature at anatase-rutile phase transition was 832 K. The grain diameter determined by XRD and HREM increased while BET surface area decrease with the increase of the calcinations temperature as well as during the phase transition from anatase to rutile.

sol-gel; TiO2; solar cell; dye-sensitized cell

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