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

Abstract

In this work, high transparent TiO2 nano-crystallinethin films have been prepared by a simple sol–gel spin coating technique.The effect of the number of layers on physical properties of TiO2 thin films were studied by 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 an increasing number of layers from 3.67 to 3.52 eV. However, the FTIR reflectance spectra show the existence of functional groups and chemical bonding.The films' electrical properties measurement indicated substantial enhancement in the resistivity with an increasing in the number of layers from3.3×105 to 2.15×106 Ω.cm. This study indicates that TiO2 films may be a potential candidate for technological applications as solar cells, photocatalysts, and gas sensors due to their desired structural, optical, and electrical properties.

Double S‐Scheme Polydopamine/TiO2/Chlorophyll as Stable and Efficient Green Photoelectrocatalyst

“…FT‐IR spectroscopy was used to evaluate the interactions between the TiO 2 nanostructured surface and coatings, Figure 4. The absorption bands reported in the 4000–3000 cm −1 range, for all spectra, show intermolecular hydrogen and stretching vibrations of the O−H groups [33] . The weaker O−H vibration of NT/Chl, NT/PD and NT/PD‐Chl results from the decreased water dispersions in these photocatalytic films [34] .…”

“…The weaker O−H vibration of NT/Chl, NT/PD and NT/PD‐Chl results from the decreased water dispersions in these photocatalytic films [34] . In the NT spectrum, absorption bands observed in 1000 cm −1 –500 cm −1 domain are attributed to the mode of vibration [35] associated with stretching in Ti−O bonds in TiO 2 NTs [33,36] . Dye molecules need to include particular functional groups in order for them to be successfully adsorbed onto a thin film of TiO 2 .…”

“…The absorption bands reported in the 4000-3000 cm À 1 range, for all spectra, show intermolecular hydrogen and stretching vibrations of the OÀ H groups. [33] The weaker OÀ H vibration of NT/Chl, NT/PD and NT/PD-Chl results from the decreased water dispersions in these photocatalytic films. [34] In the NT spectrum, absorption bands observed in 1000 cm À 1 -500 cm À 1 domain are attributed to the mode of vibration [35] associated with stretching in TiÀ O bonds in TiO 2 NTs.…”

“…[34] In the NT spectrum, absorption bands observed in 1000 cm À 1 -500 cm À 1 domain are attributed to the mode of vibration [35] associated with stretching in TiÀ O bonds in TiO 2 NTs. [33,36] Dye molecules need to include particular functional groups in order for them to be successfully adsorbed onto a thin film of TiO 2 . According to the findings of a previous investigation, [32] the functional groups of chlorophyll dye are composed of esters, hydroxyl groups (À OH), and carbonyl groups (À CO), all of which are attached to TiO 2 .…”

Electrical properties of TiO2 films synthetized by sol-gel process

“…The anatase crystalline phase can be achieved at low temperatures compared to the rutile phase, it has greater reactivity and a simple structure, crystallizing from 400°C, which is why it is the most used crystalline phase as a gas-sensitive film [2]. TiO2 films can be synthesized by chemical and physical methods such as: Atomic Layer Deposition (ALD) [2], hydrothermal [3], Pulse Laser Deposition (PLD) [4] and sol-gel [5]. The sol-gel method has some benefits with respect to other techniques such as: low equipment cost, good homogeneity, deposits at ambient temperature, control of film thickness, porous films, among others.…”