Reversible electrochromic system based on aqueous solution containing silver

Most electrochromic devices consist of solution-based organic redox systems. A new approach to electrochromics, based on the reversible coating/dissolution of an oxide from an inorganic electrochromic electrolyte consisting of a silver-amine complex aqueous solution, has been successfully tried. The complex redox chemistry underlying the functioning of this electrochromic coating has been identified from traditional techniques such as X-ray diffraction, scanning electron microscopy and cyclic voltammetry, in addition to the helpful use of a quartz microbalance for measuring the electrode weight changes. The oxidation of Ag(I) is responsible for the coloration of the system. The optical measurements of the transmittance have been carried out on clean or polarized electrodes. The T/T0 ratio maximum and minimum have been measured between 90 and 20%. However, drawbacks of the present system are the slight irreversible formation of silver at the counter electrode and the low durability. A description of the electrochemical processes implied is presented. A few approaches aiming at improving the performances of the system are being tried. Several of them are reported and discussed. © 2001 Elsevier Science Ltd