Electrochromic devices

A method of fabricating an electrochromic device, the method comprising:

• (a) forming either (i) an electrochromic layer comprising an electrochromic material, or (ii) a counter electrode layer comprising a counter electrode material, wherein the electrochromic material comprises tungsten oxide doped with of an element selected from the group consisting of molybdenum, vanadium, and titanium, and wherein the counter electrode material comprises nickel oxide doped with tungsten and tantalum;
• (b) forming the other of the electrochromic layer and the counter electrode layer without first providing an ionically conducting and electrically insulating layer between the electrochromic layer and the counter electrode layer;
• and
• (c) after (b), forming an interfacial region between the electrochromic layer and the counter electrode layer, wherein the interfacial region comprises an ionically conducting and electrically insulating material.

An electrochromic device precursor comprising:

• (a) a substrate;
• (b) an electrochromic layer comprising an electrochromic material, wherein the electrochromic material comprises tungsten oxide doped with an element selected from the group consisting of molybdenum, vanadium, and titanium;
• and
• (c) a counter electrode layer comprising a counter electrode material, wherein the counter electrode material comprises nickel oxide doped with tungsten and tantalum,
• wherein the electrochromic device precursor does not comprise an ionically conducting and electronically insulating region between the electrochromic layer and the counter electrode layer.

A method of fabricating an electrochromic device from an electrochromic device precursor, the method comprising:

• (a) receiving an electrochromic device precursor comprising:
• (i) a substrate;
• (ii) an electrochromic layer comprising an electrochromic material, wherein the electrochromic material comprises tungsten oxide doped with an element selected from the group consisting of molybdenum, vanadium, and titanium;
• and
• (iii) a counter electrode layer comprising a counter electrode material, wherein the counter electrode material comprises nickel oxide doped with tungsten and tantalum,
• wherein the electrochromic device precursor does not comprise an ionically conducting and electronically insulating region between the electrochromic layer and the counter electrode layer;
• and
• (b) after (a), forming an ionically conducting and electrically insulating material between the electrochromic material of the electrochromic layer and the counter electrode material of the counter electrode layer.