Structural, Optical, and Electrochromic Properties of Pure and Mo-Doped WO3 Films by RF Magnetron Sputtering

Abstract

Pure and Mo-doped WO3 films were formed on ITO-coated glass substrate held at 473 K by RF magnetron sputtering technique. The structural, morphological, and optical properties of pure and Mo-doped WO3 thin films have been systematically studied. The structural properties revealed that the pure WO3 films exhibited a (020) reflection related to the orthorhombic phase of WO3, whereas Mo-doped films showed (200) reflection. The surface morphology revealed that pure WO3 films showed the dense surface and Mo-doped films contained agglomerated grains which were uniformly distributed on the surface of the substrate. The optical transmittance decreased from 85% to 75% for pure and Mo-doped WO3 films, respectively. The electrochromic properties of the films were measured by cyclic voltametry in 1 M Li2SO4 electrolyte solution. The optical modulation of pure WO3 films at near IR was 50%, and the calculated color efficiency was 33.8 cm2/C, while in Mo-doped WO3 the efficiency improved to 42.5 cm2/C.