Counter electrode for electrochromic devices
The embodiments herein relate to electrochromic stacks, electrochromic devices, and methods and apparatus for making such stacks and devices. In various embodiments, an anodically coloring layer in an electrochromic stack or device is fabricated to include nickel-tungsten-niobium-oxide (NiWNbO). This material is particularly beneficial in that it is very transparent in its clear state.
1. A method of fabricating an electrochromic stack, the method comprising:
forming a cathodically coloring layer comprising a cathodically coloring electrochromic material; and
forming an anodically coloring layer comprising nickel-tungsten-niobium-oxide, wherein the nickel-tungsten-niobium-oxide has an atomic ratio of Ni:(W+Nb) that is between about 1.5:1 and 3:1, and has an atomic ratio of W:Nb that is between about 0.2:1 and 1:1.
2. The method of claim 1 , wherein the nickel-tungsten-niobium-oxide has an atomic ratio of Ni:(W+Nb) that is between about 1.5:1 and 2.5:1.
3. The method of claim 1 , wherein forming the anodically coloring layer comprises sputtering one or more sputter targets each comprising at least one metal selected from the group consisting of nickel, tungsten, and niobium to form the nickel-tungsten-niobium-oxide.
4. The method of claim 1 , wherein the anodically coloring layer is substantially amorphous.
5. The method of claim 1 , wherein the cathodically coloring layer and the anodically coloring layer are formed in direct physical contact with one another, without a separate ion conductor layer deposited between them, and further comprising converting a portion of the cathodically coloring layer and/or a portion of the anodically coloring layer to form an ion conducting and electrically insulating interfacial region between the cathodically coloring and anodically coloring layers.
6. The method of claim 1 , wherein the anodically coloring layer comprises two or more sub-layers that have different compositions and/or morphologies.
7. The method of claim 1 , wherein the cathodically coloring electrochromic material comprises tungsten oxide.
8. The method of claim 1 , wherein the cathodically coloring layer comprises a bilayer or a graded layer, and wherein a portion of the cathodically coloring layer is superstoichiometric with respect to oxygen.
9. The method of claim 1 , wherein the composition is provided as an amorphous matrix with nanocrystals distributed throughout, wherein the nanocrystals have a mean diameter of about 50 nm or less.
10. An electrochromic device stack, comprising:
a cathodically coloring layer comprising a cathodically coloring material; and
an anodically coloring layer comprising nickel-tungsten-niobium-oxide, wherein the nickel-tungsten-niobium-oxide has an atomic ration of Ni:(W+Nb) that is between about 1.5:1 and 3:1, and has an atomic ratio of W:Nb that is between about 0.2:1 and 1:1.
11. The electrochromic device stack of claim 10 , wherein the nickel-tungsten-niobium-oxide has an atomic ratio of Ni:(W+Nb) that is between about 1.5:1 and 2.5:1.
12. The electrochromic device stack of claim 10 , wherein the anodically coloring layer is substantially amorphous.
13. The electrochromic device stack of claim 10 , wherein the anodically coloring layer comprises two or more sub-layers having different compositions and/or morphologies.
14. The electrochromic device stack of claim 10 , wherein the cathodically coloring material comprises tungsten oxide.
15. The electrochromic device stack of claim 10 , wherein the cathodically coloring layer comprises a bilayer or a graded layer, and wherein a portion of the cathodically coloring layer is superstoichiometric with respect to oxygen.
16. The electrochromic device stack of claim 10 , wherein the composition is provided as an amorphous matrix with nanocrystals distributed through, wherein the nanocrystals have a mean diameter of about 50 nm or less.