Review: recent progress in ordered macroporous electrochromic materials

Electrochromic (EC) materials have the ability to change their optical properties when exposed to a low electrical voltage. They have found a wide range of applications in smart windows, low-power displays, and spacecraft thermal control. To improve the practical applicability of EC materials, rational design and exploration of their architectures play a crucial role. Among various architectures, forms of inverse opal structure including two dimensionally and three dimensionally ordered macroporous structure (2DOM and 3DOM) exhibit outstanding and specific performance. In this review, several examples of 2DOM and 3DOM EC materials with detailed preparation methods are presented, followed by a detailed discussion of various aspects in ordered macroporous structural EC films, including common features, structure transition and photonic band gap tuning. In addition, the typical five layered design for the EC material-based device is given, as the device is of the most importance in researches as well as applications. Finally, conclusions and outlook are provided at the end of this review.