Fast switchable electrochromic properties of tungsten oxide nanowire bundles

The authors prepared uniformly shaped WO2.72 nanowire bundles using the solvothermal synthesis method. They investigated the potential of the WO2.72 nanowire bundles to be used as a cathode electrode for electrochromic devices and the effect of the Li+ insertion (or extraction) kinetics and diffusion of Li+. An electrode consisting of arrays of WO2.72 nanowire bundles was formed and used in an experiment using the Langmuir-Blodgett technique. The one-dimensional nanostructure of WO2.72 has a high Li-ion diffusion coefficient (∼5.2×10−11cm2∕s) and low charge transfer resistance (∼28.6Ω), which result in its having a fast electrochromic response time (coloring time <3.5s, bleaching time <1.1s), and outstanding high coloration efficiency (>55cm2∕C).