Investigation of the effect of Mo+2 ion concentration on linear and non-linear optical properties of tungsten trioxide thin films for optoelectronic applications

Abstract

To achieve the goal of creating a single-phase mixture of transition metal oxides with high electrical efficiency, our investigation focused on studying the linear and nonlinear optical properties of a mixture of transitional oxides that is electrophoretically colored. For finding the best ratios, we also investigated the impact of adding molybdenum ion to tungsten trioxide on the linear and non-linear optical properties of the samples made using the spray pyrolysis method on heated glass substrates. The as-deposited films were amorphous, as demonstrated by the X-ray diffraction (XRD). All of the samples were transferred to the polycrystalline and acquire a triclinic structure after the thermal annealing at 500 °C for 2 h. At room temperature, transmission and reflection measurements in the wavelength range of 300–2500 nm were utilized to evaluate the absorption coefficient. MoxW1-xO3 thin films' optical density, optical energy gap, skin depth, and Urbach's parameters were also estimated. Urbach's energy, EU, decreases from 0.355 to 0.154, eV as Mo-content rises, while Tauc's band gap energy, Eg, decreases from 2.76 to 2.56 eV. The films' static refractive indices dropped from 2.832 to 2.081 in the low-energy region and from 3.832 to 2.446 in the high-energy region. The dispersion energies and other variables were investigated using the Wemple–DiDomenico and Sellmeier models. In addition, various dispersion and nonlinear parameters were estimated and thoroughly discussed. It was observed that the improvement in the crystallinity of W1-xMoxO3 thin films led to a decrease in the values of the third-order nonlinear susceptibility (χ(3)), mainly affected by the constant refractive index, which decays with an increase in Mo concentration. Simultaneously, the conductivity of the films rises proportionally with the photon energy and Mo content, which is attributed to the concurrent increase in the dielectric constants. In this work, new approach for fabrication of quality thin film of MoxW1-xO3 was demonstrated. This is the reason for obtaining the best results, which made these films an effective contribution to many important applications. Furthermore, MoxW1-xO3 thin films perovskite has large nonlinear optical proper. These findings highlight the potential utility of these films in diverse critical optical applications, such as commercial lasers, ultra-fast signal processing in optical communication systems, sensors, environmental monitoring, medicine, manufacturing and materials processing, military applications, as well as scientific instrumentation.