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 device, the method comprising:
a. forming a first conductive layer on a substrate or receiving the substrate with the first conductive layer formed thereon;
b. cutting the first conductive layer with a laser so that a first portion of the first conductive layer is electrically isolated from a second portion of the first conductive layer by a laser trench;
c. depositing an electrochromic layer or a counter electrode layer on the first and second portions of the first conductive layer and in the laser trench;
d. depositing an ion conductor layer on the electrochromic layer or the counter electrode layer deposited in (c);
e. depositing the other of the electrochromic layer and the counter electrode layer, whichever was not deposited in (c), on the ion conductor layer;
f. depositing a second conductive layer on the other of the electrochromic layer and the counter electrode layer; and
g. applying a first bus bar and a second bus bar to the electrochromic device, wherein the first bus bar is in electrical communication with both the first portion of the first conductive layer and the second conductive layer, and wherein the second bus bar is in electrical communication with the second portion of the first conductive layer but not in electrical communication with either the second conductive layer or the first portion of the first conductive layer,
wherein the substrate is a transparent substrate and the transparent substrate is subjected to a cleaning step after b).
2. The method of claim 1 , wherein the laser trench is between about 20 μm and about 50 μm wide.
3. The method of claim 1 , wherein the laser trench is between about 300 nm and about 500 nm deep.
4. The method of claim 1 , wherein the first and second conductive layers comprise a transparent conductive oxide.
5. The method of claim 4 , wherein the transparent conductive oxide is indium tin oxide.
6. The method of claim 1 , wherein the cleaning step comprises ultrasonic conditioning to remove debris caused by the cutting with the laser.
7. The method of claim 1 , wherein depositing the electrochromic layer and/or the counter electrode layer is performed using physical vapor deposition.
8. The method of claim 1 , wherein depositing the electrochromic layer and/or the counter electrode layer comprises depositing a tungsten oxide electrochromic layer or a nickel tungsten oxide counter electrode layer.
9. The method of claim 8 , wherein the tungsten oxide electrochromic layer is doped.
10. The method of claim 8 , wherein the nickel tungsten oxide counter electrode layer is doped.
11. The method of claim 10 , wherein the nickel tungsten oxide counter electrode layer is doped with tantalum.
12. The method of claim 1 , wherein the ion conductor layer comprises a silicate-based structure.
13. The method of claim 1 , wherein the first bus bar is applied by ultrasonic soldering.
14. The method of claim 1 , further comprising depositing lithium after depositing the other of the electrochromic layer and the counter electrode layer on the ion conductor layer and before depositing the second conductive layer on the other of the electrochromic layer and the counter electrode layer.
15. The method of claim 14 , wherein depositing lithium comprises sputtering lithium metal.
16. The method of claim 15 , wherein the electrochromic layer is deposited, then the ion conductor layer, then the counter electrode layer, followed by sputtering lithium metal onto the counter electrode layer.
17. A method of fabricating an electrochromic device, the method comprising:
a. depositing a first transparent conductive oxide layer on a transparent substrate;
b. cutting the first transparent conductive oxide layer with a laser so that a first portion of the first transparent conductive oxide layer is electrically isolated from a second portion of the first transparent conductive oxide layer by a laser trench;
c. depositing an electrochromic layer on the first and second portions of the first transparent conductive oxide layer and in the laser trench;
d. depositing an ion conductor layer on the electrochromic layer;
e. depositing a counter electrode layer on the ion conductor layer;
f. depositing a second transparent conductive layer on the counter electrode layer; and
g. applying a first bus bar and a second bus bar to the electrochromic device, wherein the first bus bar is in electrical communication with both the first portion of the first conductive layer and the second conductive layer, wherein the second bus bar is in electrical communication with the second portion of the first conductive layer but not in electrical communication with either the second conductive layer or the first portion of the first conductive layer,
wherein the transparent substrate is subjected to a cleaning step after b).
18. The method of claim 17 , wherein the laser trench is between about 20 μm and about 50 μm wide.
19. The method of claim 17 , wherein the laser trench is between about 300 nm and about 500 nm deep.
20. The method of claim 17 , wherein the transparent conductive oxide is indium tin oxide.
21. The method of claim 17 , wherein the cleaning step comprises ultrasonic conditioning to remove debris caused by the cutting with the laser.
22. The method of claim 17 , wherein depositing the electrochromic layer and/or depositing the counter electrode layer are performed using physical vapor deposition.
23. The method of claim 17 , wherein the electrochromic layer is a tungsten oxide electrochromic layer and the counter electrode layer is a nickel tungsten oxide counter electrode layer.
24. The method of claim 23 , wherein the tungsten oxide electrochromic layer is doped.
25. The method of claim 23 , wherein the nickel tungsten oxide counter electrode layer is doped.
26. The method of claim 25 , wherein the nickel tungsten oxide counter electrode layer is doped with tantalum.
27. The method of claim 17 , wherein the ion conductor layer comprises a silicate-based structure.
28. The method of claim 17 , wherein the first bus bar is applied by ultrasonic soldering.
29. The method of claim 17 , further comprising depositing lithium after depositing the counter electrode layer.
30. The method of claim 29 , wherein depositing lithium comprises sputtering lithium metal.