Fabrication of low defectivity electrochromic devices
Prior electrochromic devices frequently suffer from high levels of defectivity. The defects may be manifest as pin holes or spots where the electrochromic transition is impaired. This is unacceptable for many applications such as electrochromic architectural glass. Improved electrochromic devices with low defectivity can be fabricated by depositing certain layered components of the electrochromic device in a single integrated deposition system. While these layers are being deposited and/or treated on a substrate, for example a glass window, the substrate never leaves a controlled ambient environment, for example a low pressure controlled atmosphere having very low levels of particles. These layers may be deposited using physical vapor deposition.
1. A method of fabricating an electrochromic stack, the method comprising:
depositing an electrochromic (EC) layer of the electrochromic stack;
depositing metallic lithium onto the EC layer; and
depositing a counter electrode (CE) layer of the electrochromic stack,
wherein the CE layer is formed by sequentially depositing NiWO, lithium, and NiWO.
2. The method of claim 1 , wherein the CE layer is deposited using a metal target and a ceramic target.
3. The method of claim 2 , wherein the metal target comprises lithium.
4. The method of claim 1 , wherein the CE layer is deposited using two metal targets.
5. A method of fabricating an electrochromic stack, the method comprising:
depositing a first portion of an electrochromic (EC) layer of the electrochromic stack;
depositing metallic lithium directly onto the first portion of the EC layer;
depositing a second portion of the EC layer on the metallic lithium; and
depositing a counter electrode (CE) layer of the electrochromic stack.
6. The method of claim 5 , wherein the method includes only one operation of depositing metallic lithium.
7. The method of claim 5 , wherein the EC layer is deposited in a EC station, the metallic lithium is deposited in a lithiation station, and the CE layer is deposited in a CE station.
8. The method of claim 7 , wherein the EC station, the lithiation station, and the CE station are included in an integrated deposition system.
9. The method of claim 8 , wherein the EC station, the lithiation station, and the CE station are operable to pass a substrate from one station to the next without breaking vacuum.
10. The method of claim 8 , wherein the integrated deposition system includes only one lithiation station.
11. The method of claim 5 , wherein the EC layer comprises a cathodic electrochromic material.
12. The method of claim 11 , wherein the cathodic electrochromic material comprises a tungsten oxide.
13. The method of claim 5 , wherein the CE layer comprises a nickel tungsten oxide.
14. The method of claim 5 , wherein the metallic lithium is deposited by a method selected from the group consisting of physical vapor deposition, chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition, and any combinations thereof.
15. The method of claim 5 , wherein the metallic lithium is deposited in an amount sufficient to compensate a blind charge in the EC layer.
16. The method of claim 5 , wherein the CE layer is deposited by a CE target comprising a ceramic target.
17. The method of claim 5 , wherein the CE layer is deposited by a CE target comprising lithium.
18. The method of claim 17 , wherein the CE target comprises a lithium nickel tungsten oxide.
19. The method of claim 5 , further comprising heating the electrochromic stack.