Syntheses and Applications of Inorganic Electrochromic Materials and Devices

Tungsten oxide (WO₃) nanorods were synthesized by a hydrothermal process. Transparent film was fabricated by an aggregation-deposition process of WO₃ nanorods on transparent conductive glass. The as-synthesized WO₃ nanorods exhibit good electrochromic properties. WO₃ nanopaltes were directly grown on transparent conductive glasses by a crystal-assisted hydrothermal process, showing enhanced response and coloration efficiency. These properties of WO₃ nanostructures endow their promising application in large-area smart windows. Prussian blue films were fabricated and used in color-changeable betteries.

A bi-functional Prussian blue/Aluminium device has been demonstrated for self-powered electrochromic window and self-rechargeable transparent battery. Without applying any external bias, Prussian blue can be bleached to Prussian white by connecting the Prussian blue and Al electrodes. After bleaching, the blue colour of the device can be spontaneously recovered. In this regard, the designed device can be used as an energy-saving electrochromic smart window which requires no external power source. The as-prepared device can also be used as a battery with a high output voltage. Most importantly, after discharging, such a battery can automatically self-recharge. The as-prepared device exhibits promising applications in broad fields, for example, as a self-powered smart window to perform indoor light and heat management, and as a self-rechargeable transparent battery to power some delicate devices.