Bistable mirror/transparent reversibly electrodeposited devices with TiO2 as the mediator

Abstract

Reversible electrodeposition (RED) devices exhibit both transparent and mirror states, allowing light penetration and reflection. Therefore, the incident light transmission regulates the radiant heat generation. However, the low bistability of these devices is the main limitation to their application in windows since it causes continue energy consumption to maintain the mirror state; this is mainly due to the presence of Cu ions in the electrolyte, which is the main dissolution agent of the deposited Ag metal. Thus, we used a three-layered TiO2 counter electrode as an electrochemical reaction mediator and eliminated the Cu ions. In addition, the Ag thin film pre-deposited on the working electrode effectively enhanced the bistability. The combination of three-layered TiO2 and the pre-deposited Ag film allowed a reflectance of 78% and enhanced the mirror-state maintenance of the mirror state. After switching off the voltage, the retained reflectance was 17% at three-layered TiO2 more than twice larger than that at one-layered TiO2 (7%). The bistability and reflectance increase in the proposed RED devices with respect to those based on a Cu-containing electrolyte.