Boosting the Zn2+-based electrochromic properties of tungsten oxide through morphology control

Zn 2+ -based electrochromic is a newly born technology in recent years and has attracted the attention of most researchers due to its low cost and high safety. The design of high-performance Zn 2+ -based electrochromic devices , such as large light modulation and fast color change, is still a challenge. Here, we report the improvement of Zn 2+ -based electrochromic properties by morphology control, using common electrochromic material WO 3 as the research model. The hexagonal WO 3 films with shape of nanorods and nanoflakes were prepared by hydrothermal method , where the diameter of the nanorods and the thickness of the nanoflakes are almost the same. The electrochromic characterization of WO 3 nanorods and nanoflakes at 550 nm showed that their modulation ranges were 72.4% and 61.0%, their coloration times were 3 and 9 s, their bleaching times were 2.2 and 7 s, and their coloration efficiencies were 67.6 and 53.8 cm 2  C -1 , respectively. Compared with WO 3 nanoflakes, the excellent Zn 2+ -based electrochromic properties of WO 3 nanorods show rapid electron transfer kinetics caused by large surface area. Furthermore, the prototype electrochromic devices with WO 3 nanorods were fabricated, which showed good specific capacitance and excellent electrochromic performance. The fast and large optical modulation synchronous as well as good energy storage makes the electrochromic device become a potential intelligent power supply. This morphology dependent electrochromic work provides a new vision for the construction of high-performance Zn 2+ - based electrochromic devices.