Influence of precursor solution concentration on the structural, optical and humidity sensing properties of spray-deposited TiO₂thin films

Abstract

In the present paper, the influence of precursor concentration on the structural, optical, and humidity sensing properties of spray-deposited titanium dioxide (TiO2) films are investigated. The TiO2 thin films were successfully deposited by spraying different precursor concentrations such as 0.075 M, 0.1 M, and 0.125 M of titanium trichloride solution onto glass substrates. X-ray diffractometry (XRD) studies confirmed the polycrystalline anatase phase of TiO2 with dominant (101) plane. The crystallite size was found to increase with the increase in precursor concentration. The micro-strain and dislocation density in the film was observed to decrease as the crystallite size increased. The UV–vis spectra confirmed the optical absorbance edge of the samples shifted toward lower wavelengths with increased precursor concentration. The humidity sensing properties of the synthesized material were measured by monitoring the change in resistance of the sample with the change in relative humidity. The material synthesized with 0.1 M precursor concentration, by using the spray pyrolysis method, shows good sensitivity and has a response time of 77.5 s and fast recovery time of 3 s.

Fabrication of TiO2 sensor using rapid breakdown anodization method to measure pressure, humidity and sense gases at room temperature

“…RH% varies inversely with humidity and fits exactly with the equation Y=100 / X. This result coincides with that obtained by Gapale et al [15]. This group found that the resistance of TiO 2 decreased exponentially with the increasing of RH%.…”

“…Iraqi Journal of Science, 2019, Vol. 60, No.8, pp: 1894-1703 58;; Lower sensitivity of the TiO 2 sensor at low RH% values can be attributed to the filling of larger sized pores with water vapor and then the condensation of them on its walls resulting in the filling of all empty areas of the pores [15].…”

Enhancing Structural Integrity, Optical Properties, and Room Temperature Formaldehyde Sensing Through Optimized Spray Deposition Rates

“…Specifically, the band gap values decreased from 3.38 eV to 3.26 eV. This observation is consistent with the findings reported in prior studies, 39,40 indicating a convergence of results. The reduction in the band gap associated with elevated deposition rates can be ascribed to the spatial confinement of electrons and holes, leading to energy level quantization.…”

Humidity sensing properties of spray deposited Fe doped TiO2 thin film

“…The concentration of surface charge carriers is an important factor that can affect the amount of absorbed water vapour on the surface of the samples [34,35] and can be tuned by varying concentration of dopants in the pristine TiO 2 . The conduction mechanism in chemisorbed and first physisorbed layer can be ascribed to the tunnelling of electrons, while the conduction at the second physiosorbed layer is protonic conduction or the Grotthuss conduction mechanism [36] . The second physiosorbed layer is always in equilibrium with the atmospheric humidity.…”