Electrochromic behavior of WO3 thin films prepared by GLAD

Highlights: • Amorphous WO₃ thin films deposited by the GLAD technique were found to crystallize at around 300 °C. • The structure, morphology, and electrochromic properties of annealed WO₃ were characterized. • The amorphous GLAD WO₃ films exhibited a high coloration efficiency and stable reversibility. • The transmittance modulation contrast of GLAD WO₃ films under the ± 45° incidence can be up to 11%. • WO₃ films with the birefringence character exhibited the tunable angular selectivity. WO₃ thin films fabricated by glancing angle deposition (GLAD) are proposed as excellent electrochromic coatings with favorable ion diffusion. A ∼ 500-nm film prepared by GLAD had a relatively large transmittance modulation. The crystallization structure, surface morphology, chemical state, optical and electrochromic properties of WO₃ thin films were systematically characterized upon annealing treatment. Compared with annealed WO₃ porous nanostructured films, the amorphous as-deposited films exhibited a high coloration efficiency and stable reversibility. Furthermore, the GLAD WO₃ films exhibit the tunable angular selectivity under illumination with p-polarized light because of the birefringence, which could extend the application range of nanostructured films in the electrochromic field.