Dependence of the Physical Properties of Titanium Dioxide (TiO2) Thin Films Grown by Sol-Gel (Spin-Coating) Process on Thickness

In this work, high transparent TiO2 nano-crystallinethin films have been prepared by a simple sol-gel spin coating technique. The effects of number of layers on physical properties of TiO2 thin films were studied by means X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-vis spectrophotometer, and four probes measurement. The XRD analysis confirms that TiO2 has anatase phase structure with preferred orientation of (101) direction, while the crystallite size values varied with the number of layers in the range of 16-19 nm. The films exhibit high optical transparency (>70%), reaching a maximum of 85% in the visible region with the red-shifted absorption edge, suggesting the films optical gap energy decreases with increasing number of layers from 3.67 to 3.52 eV. However, the Fourier transform infrared (FTIR) reflectance spectra show the existence of functional groups and chemical bonding. The films electrical properties measurement indicated that the substantially enhancement in the resistivity with increasing the number of layers from 3.3 x 10(5) to 2.15 x 10(6) Omega.cm. This study indicates that TiO2 films may be a potential candidate in technological applications as solar cells, photocatalysts and gas sensors due to its desired structural, optical and electrical properties. (c) 2022 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited.

Automated summary

Highly transparent TiO2 nano-crystalline thin films were prepared using a sol-gel spin coating technique. The effects of the number of layers on the physical properties of the films were studied. The results show that the films have an anatase phase structure and high optical transparency, while the optical gap energy decreases with increasing number of layers. The films also exhibit functional groups and chemical bonding, and the resistivity increases with the number of layers.