Research conducted on electrochromism in Prof. Granqvist's laboratory between 1992 and 2003 and lessons learned

An electrochromic device is a five-layer structure where at least one layer is capable of a reversible change in transmittance upon charge insertion/extraction. This paper describes the basic design principles for an electrochromic device and the role played by each layer. Based on research conducted in Prof. Granqvist's laboratory between 1992 and 2003, the paper provides a brief overview of the properties of a variety of cathodically colouring electrochromic layers, anodically colouring and optically passive ion storage layers, and electrolytes. Device performance is illustrated by the example of a switchable motorcycle helmet visor prototype.