An all-solid-state bistable electrochromic device based on an amorphous WO3-x nanostructured film

Bistable electrochromic devices (BECDs) with high energy efficiency have gained extensive attention, due to their great potential for application in the smart windows of buildings and vehicles, as well as in reflective displays. However, the current BECDs are commonly fabricated with liquid or gel electrolytes, which undermine reliability and safety during application. Herein, an all-solid-state BECD with a new structure was designed and developed. It was constructed using an amorphous nanostructured WO3-x film as the electrochromic layer, a Nafion film as the solid electrolyte, and a nanostructured NiO film as the ion storage layer. This device showed ideal performances with excellent bistability (>7 days for the colored state), a fast response (<10 s) and promising dual-band tunability, owing to its stable layered structure and high ionic conductivity. More importantly, applications of this BECD in smart windows and reflective displays have been demonstrated.