Highly Transparent Spectral Tunable Electrochromic Window Based on Solid-State WO3 Thin Films

Abstract

Energy conservation is crucial for sustainable growth. Electrochromic window devices, which regulate optical transmittance using light-tunable materials like WO₃, can significantly reduce both thermal and visual energy consumption in buildings. In this study, we developed solid-state WO₃ thin film-based electrochromic window using room-temperature sputtering. The WO₃ film was grown through reactive sputtering of a tungsten target, resulting in highly transparent films with structural and optical properties well-suitable for electrochromic devices. These films exhibit efficient coloration and fast response times. WO₃-based electrochromic devices offer superior modulation across ultraviolet, visible, and infrared (IR) wavelengths, blocking over 95% of IR wavelengths. Key performance metrics include a coloration efficiency of 96.96 cm² C⁻¹, optical modulation of 68.5% in the visible region, reversibility of 88.1%, and response time of 10 s (coloration time) and 24 s (bleaching time). These results highlight the potential of WO₃-based electrochromic windows for energy conservation, making them ideal for integration into building structures as energy-sustainable entities.