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 electrically 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 electrically conductive layer disposed on a surface of the substrate;
(b) fabricating the electrochromic stack on the first transparent electrically conductive layer, wherein the electrochromic stack comprises an electrochromic layer and a counter electrode layer;
(c) forming the second transparent electrically conductive layer on the electrochromic stack;
(d) deactivating a region of the electrochromic device to form a resistive material such that the electrochromic device is substantially non-functioning in the region without substantially deactivating other regions of the electrochromic device; and
(e) forming a bus bar on a portion of the second transparent electrically conductive layer that is over the first transparent electrically conductive layer.
2. The method of claim 1 , wherein the bus bar formed over the first transparent electrically conductive layer is formed over the region.
3. The method of claim 1 , wherein deactivating the region of the electrochromic device comprises chemically reacting material in the first transparent electrically conductive layer with a reagent.
4. The method of claim 1 , wherein deactivating the region of the electrochromic device comprises heating conductive material in the electrochromic device to form resistive material in the electrochromic device.
5. The method of claim 1 , wherein deactivating the region of the electrochromic device comprises treating the electrochromic device with a laser to deactivate the region.
6. The method of claim 1 , wherein the electrochromic device tints less than the bulk device or does not tint at all in the region.
7. The method of claim 1 , wherein the deactivating in (d) comprises preventing lithiation of the electrochromic device in the region.
8. The method of claim 1 , wherein the electrochromic layer comprises electrochromic metal oxide, and wherein the deactivating in (d) comprises reacting interstitial oxygen in the electrochromic layer with the electrochromic metal oxide to produce a stoichiometric or oxygen rich form of the electrochromic metal oxide which is not electrochromically active.
9. The method of claim 1 , wherein (e) is performed prior to performing (d).
10. The method of claim 1 , further comprising cutting the substrate to provide multiple electrochromic lites prior to (d) or (e).
11. The method of claim 1 , further comprising forming the first transparent electrically conductive layer on the surface of the substrate.