Solid state Gd-Mg electrochromic devices with ZrO2Hx electrolyte

A hydrogen based device, which consists mainly of a GdMgH5 electrochromic layer, a ZrO2Hx electrolyte and a WO3 electrochromic counter electrode, was made. When a positive voltage is applied to the GdMgH5 layer, the hydrogen moves towards the WO3 layer. The latter becomes blue while the GdMgH5 layer becomes metallic (GdMgH2), resulting in a non-transparent stack. When a negative voltage is applied to the GdMgH5 layer, the hydrogen moves back to the GdMgH2 layer. Both are electrochromic layers and therefore the stack becomes transparent again. The devices switch reversibly up to 500 times with switching times in the order of minutes. This paper deals with the deposition and in-situ loading of the devices with hydrogen and contains some preliminary information on the switching behaviour and optical properties. (C) 2001 Elsevier Science Ltd. All rights reserved.