Modification of optical and structural properties of DC magnetron sputtered tungsten oxide thin films for electrochromic application
Keywords:Electrochromic, Tungsten oxide, Reactive DC magnetron sputtering
AbstractThe optical properties of tungsten oxide thin films prepared by a reactive DC magnetron sputtering technique were investigated. The influences of O2 flow rates (15 and 18 sccm) and DC sputtering powers (5, 15 and 25 W) on the optical properties of 200 nm-thick tungsten oxide films on indium tin oxide substrates (WO3/ITO/glass) were investigated using UV-visible spectrophotometer. The results indicated that the transmission modulation in visible region between colored state and bleached state of the films increased significantly with decreasing DC sputtering power and increasing O2 flow rate. The results corresponded with the increase of film roughness and density which promoted the intercalation and deintercalation. The diffusion coefficient of the films was extracted from anodic peak current of cyclic voltammogram to determine the charge intercalation across the films. With the deposition power of 5 W and the O2 flow rate of 18 sccm, the films showed the highest transmission modulation and differential optical density in visible region of 23.35% and 0.223, respectively. This information provided an advantage for developing high performance of electrochromic devices.
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