Abstract: Thin, amorphous electrochromic layers deposited on substrate electrodes by, for example, vacuum deposition techniques, are subjected to a special heat treatment at a selected high temperature for a selected short time to convert at least a free surface portion of each layer to be exposed to the electrolyte from the amorphous form to a crystalline form while preventing excessive water loss which might adversely affect the electrochromic properties of the layer for display purposes. Crystallization of at least the free surface portion of the electrochromic layer significantly increases its etch resistance whereas retention of water in the electrochromic layer maintains satisfactory electrochromic properties for display purposes.

Abstract: Thin, amorphous electrochromic layers deposited on substrate electrodes by, for example, vacuum deposition techniques, are subjected to a special heat treatment at a selected high temperature for a selected short time to convert at least a free portion of each layer to be exposed to the electrolyte from the amorphous form to a crystalline form while preventing excessive water loss which might adversely affect the electrochromic properties of the layer for display purposes. Crystallization of at least the free surface portion of the electrochromic layer significantly increases its etch resistance whereas retention of water in the electrochromic layer maintains satisfactory electrochromic properties for display purposes.