Process optimization and effect of sputtering pressure on electrochromic properties of flexible WO3 films prepared by DC magnetron sputtering

In this study, WO3 films were prepared on flexible indium tin oxide/polyethylene terephthalate substrates through DC magnetron sputtering at approximately 40 °C, and the process parameters were optimized. The effects of the sputtering pressure on the microstructure, morphology, and electrochromic properties of the films were investigated using Raman spectroscopy, scanning electron microscopy, x-ray diffraction, atomic force microscopy, and electrochemical techniques. The results showed that the thickness, surface roughness, and grain size of the WO3 films changed with increasing pressure, and the optimal values of these parameters for excellent electrochromic properties of the WO3 films were 731, 53.5, and 1.79 nm, respectively, at 2.0 Pa. The optical modulation amplitude reached 84.66% at 455 nm, and the coloring and bleaching response times were 7.64 s and 6.76 s, respectively. The electrochemical impedance spectroscopy results showed that the films prepared at 2.0 Pa had the smallest Rct (41.63 Ω).