Mitigating defects in an electrochromic device under a bus bar
Methods are provided for fabricating electrochromic devices that mitigate formation of short circuits under a top bus bar without predetermining where top bus bars will be applied on the device. Devices fabricated using such methods may be deactivated under the top bus bar, or may include active material under the top bus bar. Methods of fabricating devices with active material under a top bus bar include depositing a modified top bus bar, fabricating self-healing layers in the electrochromic device, and modifying a top transparent conductive layer of the device prior to applying bus bars.
1. A method of fabricating an electrochromic device comprising an electrochromic stack between a first and a second transparent, electronically conductive layer configured to establish an electrical potential across the electrochromic stack and thereby cause optical switching of the electrochromic device, the method comprising:
(a) receiving a substrate with the first transparent, electronically conductive layer disposed on a surface of the substrate;
(b) fabricating the electrochromic stack on the first transparent, electronically conductive layer, wherein the electrochromic stack comprises an electrochromic layer and a counter electrode layer;
(c) forming the second transparent, electronically conductive layer on the electrochromic stack;
(d) forming a bus bar on a region of the second transparent, electronically conductive layer, wherein the region is over the first transparent, electronically conductive layer; and
(e) performing a short mitigation operation that
(i) prevents electrical shorts from forming between the second transparent, electronically conductive layer and a layer of the electrochromic device in the region underneath the bus bar, and/or
(ii) removes electrical shorts that have formed between the second transparent, electronically conductive layer and a layer of the electrochromic device in the region underneath the bus bar,
wherein (e) is performed without substantially deactivating the electrochromic device in the region under the bus bar after fabricating the electrochromic stack and the second transparent, electronically conductive layer.
2. The method of claim 1 , further comprising continuously feeding the substrate from a roll of the substrate to an apparatus that coats the electrochromic stack on the substrate.
3. The method of claim 2 , wherein the substrate comprises a flexible glass.
4. The method of claim 1 , wherein forming the first transparent, electronically conductive layer, fabricating the electrochromic stack, and forming the second transparent, electronically conductive layer are performed sequentially in a sputter coating apparatus, which coats the surface of the substrate with the first and the second transparent, electronically conductive layers and the electrochromic stack.
5. The method of claim 1 , wherein the first transparent, electronically conductive layer is formed in an apparatus where the electrochromic stack is fabricated.
6. The method of claim 1 , wherein operations (b) and (c) are performed sequentially in a sputter coating apparatus, which coats the surface of the substrate with the first and the second transparent, electronically conductive layers and the electrochromic stack, and wherein operation (d) is performed outside the sputter coating apparatus.
7. The method of claim 1 , wherein the short mitigation operation comprises forming a barrier layer between the bus bar and the second transparent, electronically conductive layer.
8. The method of claim 1 , wherein the short mitigation operation comprises applying a stimulus that heals the existing shorts between the second transparent, electronically conductive layer and the layer of the electrochromic device.
9. The method of claim 1 , wherein the short mitigation operation comprises blocking passages in the second transparent, electronically conductive layer at points where the shorts form.
10. The method of claim 1 , wherein the method is performed without isolating a region of the first transparent, electronically conductive layer or the electrochromic stack before forming the second transparent, electronically conductive layer.
11. The method of claim 1 , wherein the method is performed without pre-defining where the bus bar for the second transparent, electronically conductive layer will be formed prior to completing the electrochromic device and second transparent, electronically conductive layer.
12. The method of claim 10 , further comprising forming one or more additional bus bars on the second transparent, electronically conductive layer and/or the first transparent, electronically conductive layer.
13. The method of claim 12 , further comprising cutting the substrate to provide multiple electrochromic lites.
14. The method of claim 13 , wherein the cutting is performed prior to forming the bus bar.
15. The method of claim 13 , wherein the cutting is performed after forming the bus bar.