A reversible inorganic electrochromic solution system

Electrochromic devices that respond to varied levels of applied electrical potential by changing light opacity are presently prepared from either inse rtion compounds or reversible electrodeposition of metals from solution. We report here another approach to electrochromics based on the reversible de position/dissolution of silver oxide onto FTO-coated glass from an aqueous solution containing silver (I)-ammonia complexes. The basic redox chemistry underlying the functioning of this electrochromic system has been identifi ed using traditional techniques such as X-ray diffraction, scanning electro n microscopy, and cyclic voltammetry, as well as a quartz nanobalance for m easuring the working electrode weight at different potentials. The AgNH3+ < -> AgO reaction is responsible for the coloration/decoloration of the worki ng electrode, which can be repeatedly cycled between various states of visu al opacity. Optical measurements reveal that the transmittance of the worki ng electrode in the visible region drastically drops from 80% without silve r oxide deposition to 4% when it is coated with a silver oxide him. (C) 200 0 Elsevier Science B.V. All rights reserved.