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 a heterogeneous structure, for example a heterogeneous composition and/or morphology. Such heterogeneous anodically coloring layers can be used to better tune the properties of a device.
1. An electrochromic device comprising:
a substrate;
an electrochromic layer disposed on or over the substrate, said electrochromic layer comprising a cathodically tinting electrochromic material; and
an anodically tinting counter electrode layer also disposed on or over the substrate, said counter electrode layer comprising (a) a first sublayer comprising a first nickel tungsten oxide composition, and (b) a second sublayer comprising a second nickel tungsten oxide composition, wherein the first and second nickel tungsten oxide compositions have different relative amounts of nickel and/or tungsten, and wherein the first sublayer is disposed between the electrochromic layer and the second sublayer.
2. The electrochromic device of claim 1 , wherein the second nickel tungsten oxide composition further comprises tantalum, niobium, tin, or a combination thereof.
3. The electrochromic device of claim 2 , wherein the second nickel tungsten oxide composition comprises tantalum.
4. The electrochromic device of claim 2 , wherein the second nickel tungsten oxide composition comprises niobium.
5. The electrochromic device of claim 2 , wherein the second nickel tungsten oxide composition comprises tin.
6. The electrochromic device of claim 3 , wherein the first nickel tungsten oxide composition further comprises tantalum, and wherein the second nickel tungsten oxide composition comprises a greater concentration of tantalum than does the first nickel tungsten oxide composition.
7. The electrochromic device of claim 4 , wherein the first nickel tungsten oxide composition further comprises niobium, and wherein the second nickel tungsten oxide composition comprises a greater concentration of niobium than does the first nickel tungsten oxide composition.
8. The electrochromic device of claim 5 , wherein the first nickel tungsten oxide composition further comprises tin, and wherein the second nickel tungsten oxide composition comprises a greater concentration of tin than does the first nickel tungsten oxide composition.
9. The electrochromic device of claim 2 , wherein the counter electrode layer further comprises a third sublayer comprising a third nickel tungsten oxide composition wherein the first, second, and third nickel tungsten oxide compositions have different relative amounts of nickel and/or tungsten, and wherein the second sublayer is disposed between the first sublayer and the third sublayer.
10. The electrochromic device of claim 9 , wherein the third nickel tungsten oxide composition further comprises tantalum, niobium, tin, or a combination thereof.
11. The electrochromic device of claim 10 , wherein the third nickel tungsten oxide composition comprises tantalum.
12. The electrochromic device of claim 10 , wherein the third nickel tungsten oxide composition comprises niobium.
13. The electrochromic device of claim 10 , wherein the third nickel tungsten oxide composition comprises tin.
14. The electrochromic device of claim 11 , wherein the second and third nickel tungsten oxide compositions each comprise tantalum, and wherein the third nickel tungsten oxide composition comprises a greater concentration of tantalum than does the second nickel tungsten oxide composition.
15. The electrochromic device of claim 12 , wherein the second and third nickel tungsten oxide compositions each comprise niobium, and wherein the third nickel tungsten oxide composition comprises a greater concentration of niobium than does the second nickel tungsten oxide composition.
16. The electrochromic device of claim 13 , wherein the second and third nickel tungsten oxide compositions each comprise tin, and wherein the third nickel tungsten oxide composition comprises a greater concentration of tin than does the second nickel tungsten oxide composition.
17. The electrochromic device of claim 1 , wherein the counter electrode layer further comprises a third sublayer comprising a third nickel tungsten oxide composition, wherein the second nickel tungsten oxide composition further comprises metal M1, wherein the third nickel tungsten oxide composition further comprises metal M2, and wherein metals M1 and M2 are different from one another.
18. The electrochromic device of claim 17 , wherein the second nickel tungsten oxide composition is substantially free of metal M2, and wherein the third nickel tungsten oxide composition is substantially free of metal M1.
19. The electrochromic device of claim 1 , wherein the first sublayer of the counter electrode layer is a flash layer having a thickness of between about 10 nm and about 80 nm.
20. The electrochromic device of claim 19 , wherein the thickness of the flash layer is between about 10 nm and about 50 nm.
21. The electrochromic device of claim 20 , wherein the thickness of the flash layer is between about 10 nm and about 30 nm.
22. The electrochromic device of claim 19 , wherein the first sublayer has an electronic resistivity between about 1 and 5×10 10 Ohm-cm.
23. The electrochromic device of claim 1 , wherein the first sublayer comprises an electronic resistivity between about 1 and 5×10 10 Ohm-cm.
24. The electrochromic device of claim 1 , wherein each of the first and second sublayers of the counter electrode layer has a thickness between about 20 nm and about 200 nm.
25. The electrochromic device of claim 24 , wherein the thickness of the first sublayer differs from the thickness of the second sublayer by between about 50 nm and about 200 nm.
26. The electrochromic device of claim 14 , wherein the second nickel tungsten oxide composition comprises between about 2-10% atomic tantalum, and wherein the third nickel tungsten oxide composition comprises between about 5-20% atomic tantalum.
27. The electrochromic device of claim 26 , wherein the first sublayer substantially consists of nickel tungsten oxide, the second sublayer substantially consists of nickel tungsten tantalum oxide that is between about 2-10% atomic tantalum, and the third sublayer substantially consists of nickel tungsten tantalum oxide that is between about 5-20% atomic tantalum.
28. The electrochromic device of claim 27 , wherein the nickel tungsten tantalum oxide in the second sublayer is about 4% atomic tantalum, and the nickel tungsten tantalum oxide in the third sublayer is about 8% atomic tantalum.
29. The electrochromic device of claim 15 , wherein the second nickel tungsten oxide composition comprises between about 2-10% atomic niobium, and wherein the third nickel tungsten oxide composition comprises between about 5-20% atomic niobium.
30. The electrochromic device of claim 29 , wherein the first sublayer substantially consists of nickel tungsten oxide, the second sublayer substantially consists of nickel tungsten niobium oxide that is between about 2-10% atomic niobium, and the third sublayer substantially consists of nickel tungsten niobium oxide that is between about 5-20% atomic niobium.
31. The electrochromic device of claim 30 , wherein the nickel tungsten niobium oxide in the second sublayer is about 4% atomic niobium, and the nickel tungsten niobium oxide in the third sublayer is about 8% atomic niobium.
32. The electrochromic device of claim 16 , wherein the second nickel tungsten oxide composition comprises between about 2-10% atomic tin, and wherein the third nickel tungsten oxide composition comprises between about 5-20% atomic tin.
33. The electrochromic device of claim 32 , wherein the first sublayer substantially consists of nickel tungsten oxide, the second sublayer substantially consists of nickel tungsten tin oxide that is between about 2-10% atomic tin, and the third sublayer substantially consists of nickel tungsten tin oxide that is between about 5-20% atomic tin.
34. The electrochromic device of claim 33 , wherein the nickel tungsten tin oxide in the second sublayer is about 4% atomic tin, and the nickel tungsten tin oxide in the third sublayer is about 8% atomic tin.
35. The electrochromic device of claim 1 , wherein the second nickel tungsten oxide composition further comprises a metal that is not present in the first nickel tungsten oxide composition.
36. The electrochromic device of claim 1 , wherein at least one of the first and second sublayers of the counter electrode layer comprises a graded composition.
37. The electrochromic device of claim 1 , wherein the first and second sublayers of the counter electrode layer each have a morphology that is a mixture of amorphous and nanocrystalline phases with nanocrystallites having a diameter of less than about 50 nm.