Modification in the microstructural and electrochromic properties of spray-pyrolysed WO3 thin films upon Mo doping

WO3 thin films were grown onto the glass and fluorine-doped tin oxide-coated glass substrates using chemical spray pyrolysis technique. X-ray diffraction analyses reveal that all the films possess orthorhombic phase of WO3. Morphologies of the films have been found to vary with Mo-doping concentrations. Three-dimensional atomic force micrographs reveal that the 5 at% Mo-doped film has the maximum image surface area and is optimal for improved electrochromic performance. Cyclic voltammetry studies show that the cathodic and anodic peak current densities have the highest values for the 5 at% Mo-doped WO3 film. Relative to the undoped film, the change from coloured to bleached state is faster for the 5 at% Mo-doped WO3 film. Considering the reversibility and the switching response from chronoamperometry and the coloration efficiency from cyclic voltammetry, it has been concluded that the 5 at% Mo-doped WO3 film has an optimal electrochromic response.