Comparison between wet vs dry methods: Fabrication process of tungsten oxide thin film enhances performances of smart windows based on electrochromism

In response to the increasing demand for smart window technologies in autonomous vehicles, an electrochromic device (ECD), which can control solar energy transmission, such as light and heat, through dynamic changes in its optical properties, has emerged as a promising solution. This study focuses on improving the performance of complementary ECDs incorporating Prussian blue and tungsten oxide (WO3) thin films, which were previously developed. We employ two fabrication methods, wet and dry, based on spin-coating and vapor deposition, respectively, to prepare WO3 thin films and then evaluate their impact on the performance of ECDs. The increasing thickness of WO3 films in the wet-method-based ECDs resulted in enhanced switching velocity between the colored and colorless states and conversely decreased the switching efficiency and optical density contrast. On the other hand, the dry-method-based ECDs provided balanced improvements across all performance metrics. These findings highlight the potential of fabrication methods in optimizing ECD performance for future applications in autonomous vehicles and smart windows.