Tuning the transmittance and the electrochromic behavior of WO3-based nanostructured thin films by glancing angle deposition

In recent years, WO_x electrochromic thin films by glancing angle deposition (GLAD) have been demonstrated to be preponderant due to the favorable diffusion of ions. The WO₃-based thin films is deposited with GLAD technique in the electron beam deposition system in this paper. The electrochromic behaviors of WO₃ nanostructured thin films with different thicknesses and annealing temperatures have been characterized and analyzed. The amorphous WO₃ porous layer with 500nm thickness exhibits outstanding electrochromic properties of fast response, high coloration efficiency and stable reversibility, and the annealing treatment results in the crystallization, and causes the degradation of electrochromic properties due to the irreversible degradation of microstructures. For improving the electrochromic property of WO₃-based nanostructure further, the material and electrochromic properties of W_xTi_yO_1-x-y nanostructures and WO₃/TiO₂ composite structures by GLAD technique have been analyzed and compared with amorphous WO₃ thin films. The range of transmittance modulation could be easily tuned by the changes of W/Ti ratio and WO₃/TiO₂ thickness. The results show that this type of switchable coatings by GLAD can be used as smart window components with well controlled optical properties.