Hybrid electrochromic device with transparent electrolyte

Hybrid electrochromic (EC) devices present an interesting configuration in which the advantage of both solid-state and liquid-based devices can be combined in order to optimize the device performances. In this configu-ration, a solid-state EC material is combined with a redox couple dissolved in the electrolyte. The redox elec-trolyte offers an unlimited charge capacity, thus allowing to fully exploit the electrochromic properties of the EC material. Here, we present a thiolate/disulphide (T-/T2) redox couple as a new redox shuttle for EC devices. In order to transfer the advantages of the redox couple to a solid state device, it was combined with a fully transparent thermally curable vinyl-acetate polymer. The obtained EC device was compared with that based on I-/I3- showing higher transparency in the visible region of the solar spectrum and higher coloration efficiency. Most interestingly, the device based on T-/T2 shows a slower self-bleaching process and it only loses 30% of its coloration after 1 h at open circuit. Such characteristic represents a great advantage for smart windows appli-cations since it is not necessary to apply potential to maintain the device coloration, thus allowing a great energy saving.

Automated summary

Hybrid electrochromic devices combine the advantages of solid-state and liquid-based devices to optimize their performances. In this study, a new redox shuttle, thiolate/disulphide, was combined with a transparent thermally curable vinyl-acetate polymer to create a solid-state electrochromic (EC) device. Compared to a device based on I-/I3-, the EC device based on T-/T2 showed higher transparency and coloration efficiency in the visible region of the solar spectrum. Additionally, it displayed a slower self-bleaching process and only lost 30% of its coloration after 1 hour at open circuit, making it highly suitable for smart windows applications that require energy-saving.