Electrochromic devices
Conventional electrochromic devices frequently suffer from poor reliability and poor performance. Improvements are made using entirely solid and inorganic materials. Electrochromic devices are fabricated by forming an ion conducting electronically insulating interfacial region that serves as an IC layer. In some methods, the interfacial region is formed after formation of an electrochromic and a counter electrode layer, which are in direct contact with one another. The interfacial region contains an ion conducting electronically insulating material along with components of the electrochromic and/or the counter electrode layer. Materials and microstructure of the electrochromic devices provide improvements in performance and reliability over conventional devices. In addition to the improved electrochromic devices and methods for fabrication, integrated deposition systems for forming such improved devices are also disclosed.
1. An electrochromic device precursor comprising:
(a) a substrate;
(b) a first transparent conducting oxide layer on the substrate;
(c) a stack on the first transparent conducting oxide layer, the stack comprising:
(i) an electrochromic layer comprising an electrochromic material;
(ii) a counter electrode layer comprising a counter electrode material that serves as a reservoir of ions; where the stack does not comprise an ion conducting and electrically insulating region between the electrochromic layer and the counter electrode layer; and
(d) a second transparent conducting oxide layer on top of the stack;
wherein at least one of the electrochromic material and the counter electrode material contains lithium.
2. The electrochromic device precursor of claim 1 , wherein the electrochromic layer comprises tungsten oxide and the counter electrode layer comprises nickel tungsten oxide.
3. The electrochromic device precursor of claim 1 , wherein the electrochromic layer is tungsten oxide with a superstoichiometric oxygen content at least at the interface with the counter electrode layer.
4. The electrochromic device precursor of claim 1 , wherein the electrochromic layer is between about 300 nm and about 600 nm thick and the counter electrode layer is between about 150 nm and about 300 nm thick.
5. The electrochromic device precursor of claim 1 , wherein the electrochromic material comprises a metal oxide and a dopant.
6. The electrochromic device precursor of claim 5 , wherein the dopant is selected from the group consisting of: molybdenum, niobium, vanadium, titanium, and combinations thereof.
7. The electrochromic device precursor of claim 6 , wherein the metal oxide comprises a material selected from the group consisting of: tungsten oxide, molybdenum oxide, niobium oxide, titanium oxide, vanadium oxide, and combinations thereof.
8. The electrochromic device precursor of claim 7 , wherein the metal oxide comprises tungsten oxide, and wherein the dopant is molybdenum.
9. The electrochromic device precursor of claim 7 , wherein the metal oxide comprises tungsten oxide and wherein the dopant is titanium.
10. The electrochromic device precursor of claim 1 , wherein the counter electrode material comprises a metal oxide selected from the group consisting of: nickel oxide, nickel tungsten oxide, nickel vanadium oxide, nickel chromium oxide, nickel aluminum oxide, nickel manganese oxide, nickel magnesium oxide, chromium oxide, manganese oxide, Prussian blue, cerium titanium oxide, cerium zirconium oxide, vanadium oxide, and combinations thereof.
11. The electrochromic device precursor of claim 10 , wherein the counter electrode material further comprises a dopant selected from the group consisting of: tantalum and tungsten.
12. The electrochromic device precursor of claim 11 , wherein the counter electrode material comprises nickel tungsten oxide doped with tantalum.
13. The electrochromic device precursor of claim 11 , wherein the electrochromic material comprises tungsten oxide doped with molybdenum and/or titanium.
14. The electrochromic device precursor of claim 10 , wherein the metal oxide comprises nickel oxide.
15. The electrochromic device precursor of claim 1 , wherein the precursor comprises a structure that produces an ion conducting and electrically insulating region between the electrochromic layer and the counter electrode layer when the electrochromic device precursor is converted to an electrochromic device by heating.
16. The electrochromic device precursor of claim 15 , wherein the electrochromic layer and/or the counter electrode layer comprise an oxygen-rich portion that is a precursor to the ion conducting and electrically insulating region between the electrochromic layer and the counter electrode layer.
17. The electrochromic device precursor of claim 16 , wherein the oxygen-rich portion is provided in the electrochromic layer and adjacent to the counter electrode layer.
18. The electrochromic device precursor of claim 1 , further comprising a capping layer on the second transparent conductive oxide layer.
19. The electrochromic device precursor of claim 18 , wherein the capping layer has a thickness between about 30-100 nm.
20. A method of fabricating an electrochromic device from an electrochromic device precursor, the method comprising:
(a) receiving an electrochromic device precursor comprising:
(i) an electrochromic layer comprising an electrochromic material,
(ii) a counter electrode layer comprising a counter electrode material that serves as a reservoir of ions, wherein there is not a layer of material that is substantially ion conducting and substantially electronically insulating positioned between the electrochromic layer and the counter electrode layer, wherein at least one of the electrochromic layer and the counter electrode layer contains lithium; and
(b) after receiving the electrochromic device precursor, forming a material that is substantially ion conducting and substantially electronically insulating between the electrochromic material in the electrochromic layer and the counter electrode material in the counter electrode layer, thereby forming the electrochromic device.
21. The method of claim 20 , wherein (b) comprises exposing the electrochromic device precursor to heat.
22. The method of claim 21 , wherein exposing the electrochromic device precursor to heat comprises heating the electrochromic device precursor at a temperature between about 150-450° C. for a duration between about 10-30 minutes.
23. The method of claim 21 , wherein exposing the electrochromic device precursor to heat comprises heating the electrochromic device precursor at a temperature between about 250-350° C. for a duration between about 20-40 minutes.
24. The method of claim 21 , wherein exposing the electrochromic device precursor to heat comprises a multistep thermochemical conditioning process comprising:
(i) heating the electrochromic device precursor under an inert atmosphere,
(ii) heating the electrochromic device precursor under an oxygen atmosphere, and
(iii) heating the electrochromic device precursor in air.
25. The method of claim 24 , wherein (i) comprises heating the electrochromic device precursor under an inert atmosphere at a temperature between about 150-450° C. for a duration between about 10-30 minutes, wherein (ii) comprises heating the electrochromic device precursor under an oxygen-containing atmosphere for a duration between about 1-15 minutes, and wherein (iii) comprises heating the electrochromic device precursor in air at a temperature between about 250-350° C. for a duration between about 20-40 minutes.
26. The method of claim 25 , wherein (i) comprises heating the electrochromic device precursor under an inert atmosphere at a temperature of about 250° C. for a duration of about 15 minutes, wherein (ii) comprises heating the electrochromic device precursor under the oxygen-containing atmosphere for a duration of about 5 minutes, and wherein (iii) comprises heating the electrochromic device precursor in air at a temperature between about 300° C. for a duration of about 30 minutes.