Effect of preparation parameters on the properties of TiO 2 nanoparticles for dye sensitized solar cells

Abstract

Nano-sized TiO 2 powders have been prepared by sol–gel method. Influences of the different preparation parameters on the TiO 2 nano-powder properties were investigated. Thermal gravimetric analysis (TGA) was used to examine the thermal properties of the produced TiO 2 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 °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 °C. High resolution transmission electron microscopy (HRTEM) showed spherical nanoparticles of 8–9 nm at autoclaving temperature of 130 °C, while elongated nanoparticles of 14–18 nm in length and 9 nm in width were measured at autoclaving temperature of 245 °C. The solar cell performance was measured for various TiO 2 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.