Effect of preparation parameters on the properties of TiO2 nanoparticles for dye sensitized solar cells

Nano-sized TiO2 powders have been prepared by sol-gel method. Influences of the different preparation parameters on the TiO2 nano-powder properties were investigated. Thermal gravimetric analysis (TGA) was used to examine the thermal properties of the produced TiO2 nanoparticles. Yield efficiency of the resulted nanoparticles was calculated and the reaction efficiency was estimated. Maximum efficiency of 98.9% was achieved at autoclaving temperature of 245 degrees C for time duration of 12 h. X-ray diffraction analyses show the presence of anatase structure at low and high autoclaving temperatures. Fraction of rutile phase is detected with increasing the calcination temperature and reach 40% at 850 degrees C. High resolution transmission electron microscopy (HRTEM) showed spherical nanoparticles of 8-9 nm at autoclaving temperature of 130 degrees C, while elongated nanoparticles of 14-18 nm in length and 9 nm in width were measured at autoclaving temperature of 245 degrees C. The solar cell performance was measured for various TiO2 dye sensitized solar cells. Samples of high autoclaving temperature gave an improvement in the efficiency to be 8.5% while those of lower autoclaving temperature had an efficiency of 7.29%. An enhancement in both open circuit voltage (V-oc) and fill factor (FF) is obviously detected, where elongated nanoparticles are measured by HRTEM, which improved the electronic conductivity and consequently FF and V-oc. (C) 2010 Elsevier Ltd. All rights reserved.