High contrast and fast switching speed multi-hue electrochromic films containing transition metal ion-doped nanomaterials

In this paper we focus on the electrochromic property of a multicolour film containing transition metal ion doped hexagonal tungsten bronze (TM-HTB), Fe0.20-HTB, and Cu0.15-HTB. Compared with the HTB or Mo-HTB films, the colour range of the TM-HTB films was greatly extended, while the switching speed, colour contrast and electrochromic efficiency were almost unchanged. The Fe0.20-HTB film could change colour from orange to blue. Its colour contrast and coloration efficiency are 46.6% and 38.1, respectively. And the Cu0.15-HTB film changes from yellow-green to dark blue under the control of an electric signal. Its colour contrast and coloration efficiency are 38.7% and 54.2, respectively. The switching speed for Fe0.20-HTB and Cu0.15-HTB film is 8 s(reduction)/2 s(oxidation) and 8.5 s(reduction)/2 s(oxidation).