INVITED: Electrochromics on a roll

Electrochromic thin-film devices are able to change their throughput of visible light and solar energy under the action of a low voltage. These devices are essentially thin-film batteries whose charging state is manifested as optical absorption. Electrochromics is currently being used in buildings—on “smart” windows and glass facades—and impart energy efficiency jointly with indoor comfort. Most of today’s electrochromic devices utilize coatings on float glass but another option, which is discussed in this talk, is to deposit onto flexible plastic web. The electrochromic device is then implemented as a thin foil which, in its turn, is used for glass lamination. This approach thus separates electrochromic functionality from glass lamination and window fabrication, which makes the technology compatible with the current value chain for window manufacturing. The talk introduces electrochromic device technology and discusses manufacturing aspects and optical and electrical properties. Furthermore, the talk ventures to look into the future and gives a brief discussion of thermochromic technology, for diminishing solar energy transmittance upon increased temperature, and how this technology can be integrated with electrochromism for superior performance.