Transparent inorganic multicolour displays enabled by zinc-based electrochromic devices

Abstract

Electrochromic displays have been the subject of extensive research as a promising colour display technology. The current state-of-the-art inorganic multicolour electrochromic displays utilize nanocavity structures that sacrifice transparency and thus limit their diverse applications. Herein, we demonstrate a transparent inorganic multicolour display platform based on Zn-based electrochromic devices. These devices enable independent operation of top and bottom electrochromic electrodes, thus providing additional configuration flexibility of the devices through the utilization of dual electrochromic layers under the same or different colour states. Zn-sodium vanadium oxide (Zn-SVO) electrochromic displays were assembled by sandwiching Zn between two SVO electrodes, and they could be reversibly switched between multiple colours (orange, amber, yellow, brown, chartreuse and green) while preserving a high optical transparency. These Zn-SVO electrochromic displays represent the most colourful transparent inorganic-based electrochromic displays to date. In addition, the Zn-SVO electrochromic displays possess an open-circuit potential (OCP) of 1.56V, which enables a self-colouration behaviour and compelling energy retrieval functionality. This study presents a new concept integrating high transparency and high energy efficiency for inorganic multicolour displays. Electrochromic displays: superior colourTransparent electrochromic displays with a richer colour palette are now possible. Electrochromic displays, which change their colour due to electrochemistry, are receiving interest due to their low power consumption but a lack of colours is problematic. Wu Zhang and coworkers from the University of Alberta in Canada and Louisiana State University in the USA fabricated multicolour displays using sodium ion stabilized vanadium oxide nanorods (Zn-SVO) as the electrochromic material. Two layers of this material, separated by a layer of zinc and a gel electrolyte were sandwiched between glass coated with indium tin oxide. Application of a small voltage causes the SVO film to exhibit a reversible switch between orange, yellow and green. The use of two independently-controlled films in the display provides a broader range of colours (orange, amber, yellow, brown, chartreuse and green).