Too blue to be good? A critical overview on the electrochromic properties and applications of Prussian blue

Prussian blue was discovered over 300 years ago, but its electrochromic properties were first described in 1978. Since about 1982, intensive work has been carried out on the development of electrochromic elements using Prussian blue. This article also describes the modern understanding of the stoichiometry and structure of Prussian blue. In addition, a structured overview of the numerous manufacturing processes of Prussian blue films is given. The various electrochromic device configurations using Prussian blue are presented. This critical review also describes and discusses the main successes and problems of the development effort towards commercial electrochromic devices with Prussian blue spanning over 40 years. In particular, color rendering problems when using Prussian blue in electrochromic devices for building glazing are discussed. Finally, impetus for further work is given.