Improved electrochromic performance of ordered macroporous tungsten oxide films for IR electrochromic device

Electrochromic performance of tungsten oxide (WO3) has attracted extensive interest due to its applications in smart windows, spacecraft thermal control and other optical devices. Here we report ordered macroporous WO3 thin films prepared by the template-assisted sol-gel method. The principle finding of the paper is that the ordered multi-layer interconnected porous structure facilitates the diffusion of ions/electrons as well as the light transmission. Consequently we see improved IR optical modulation and faster response time in the macroporous WO3 films. Moreover, both small pore size and perfection of ordered porous structure contribute to the improved electrochromic performance. These results have obvious practical relevance for fast near IR electrochromic devices exemplified by aerospace thermal control systems. (C) 2012 Elsevier B.V. All rights reserved.