Sol-Gel Spin Coating Synthesis of TiO₂ Nanostructure and Its Optical Characterization

Abstract

This work focuses on the sol-gel spin coating technique of TiO 2 nanostructure synthesis and its characterization. Though various methods have been used to fabricate TiO 2 nanostructure, much effort has not been exerted to achieve better photoresponsive and narrowly dispersed TiO 2 nanostructure using the sol-gel spin coating method. Therefore, it is imperative to realize the synthesis of TiO 2 nanostructures, and investigate their properties. In this work, TiO 2 is synthesized by sol-gel spin coating technique using titanium tetraisopropoxide, isopropanol, acetic acid and deionized water as starting materials and deposited on borosilicate glass substrates. The effects of annealing temperatures (300 ˚ C, 400 ˚ C and 500 ˚ C) on the structural and optical properties of the films were investigated by different techniques: Scanning Electron Microscopy (SEM), optical microscopy and UV-visible spectrophotometry. The optical characterization showed the direct band gap at 3.7 eV, 3.6 eV and 3.4 eV for 300 ˚ C, 400 ˚ C and 500 ˚ C, respectively, and the optical transmittance and reflectance spectra showed a greater performance at 500 ˚ C. The grain sizes obtained from SEM annealed at 300 ˚ C, 400 ˚ C and 500 ˚ C are found to be about 6.0 nm, 5.0 nm and 4.0 nm respectively. The grain size of TiO 2 nanostructure films decreased with increasing annealing temperatures. The results clearly indicated that the sol-gel spin coating synthesis of TiO 2 nanostructure and post-thermal treatment at 500 ˚ C cooled naturally at room temperature result in better photoresponsive and narrowly dispersed TiO 2 nanostructure films with higher photoresponsive and good optical properties.