Electrochromic devices
View Patent ↗Prior electrochromic devices frequently suffer from poor reliability and poor performance. Some of the difficulties result from inappropriate design and construction of the devices. In order to improve device reliability two layers of an electrochromic device, the counter electrode layer and the electrochromic layer, can each be fabricated to include defined amounts of lithium. Further, the electrochromic device may be subjected to a multistep thermochemical conditioning operation to improve performance. Additionally, careful choice of the materials and morphology of some components of the electrochromic device provides improvements in performance and reliability. In some devices, all layers of the device are entirely solid and inorganic.
1. A method of fabricating an electrochromic window, the method comprising:
sequentially depositing layers on a glass substrate while in a substantially vertical orientation at multiple deposition stations within a single pass integrated vacuum deposition system to fabricate an entirely inorganic and solid state electrochromic device having a low level of electric short related defects, visible during tinting of the electrochromic device;
depositing a tungsten oxide electrochromic layer while the glass substrate is in a first deposition station of the multiple deposition stations;
depositing a nickel tungsten oxide counter electrode layer while the glass substrate is in a second deposition station of the multiple deposition stations to form a stack of the electrochromic device including the electrochromic layer and the counter electrode layer;
depositing lithium while the glass substrate is in a third deposition station of the multiple deposition stations; and
depositing a transparent conductive oxide while the glass substrate is in a fourth deposition station of the multiple deposition stations,
wherein the glass substrate is in the substantially vertical orientation during translational movement between the multiple stations depositing the layers on the glass substrate within the integrated vacuum deposition system,
wherein the glass substrate does not leave the integrated vacuum deposition system at any time during the sequential deposition of the electrochromic layer and the counter electrode layer, and
wherein the glass substrate has a size of at least 20×20 inches and up to about 80 inches by 120 inches.
2. The method of claim 1 , wherein depositing the nickel tungsten oxide counter electrode layer produces a nickel tungsten oxide in which the atomic ratio of tungsten to nickel is between about 0.15 to 0.35.
3. The method of claim 1 , wherein the electrochromic device further includes an ion conducting layer comprising a silicate, a silicon oxide, a tungsten oxide, a tantalum oxide, a niobium oxide or a borate.
4. The method of claim 1 , wherein the electrochromic layer comprises WO x , wherein x is less than 3.0 and at least 2.7.
5. The method of claim 4 , wherein the WO x has a substantially nanocrystalline morphology.
6. The method of claim 5 , wherein depositing the counter electrode layer comprises sputtering a target comprising about 10 to about 40 atomic % of tungsten in nickel in an oxygen containing environment to produce the layer of nickel tungsten oxide.
7. The method of claim 3 , wherein each of (i) the tungsten oxide electrochromic layer, (ii) the inorganic and solid lithium ion conducting layer, and (iii) the nickel tungsten oxide counter electrode layer is physical vapor deposited.
8. The method of claim 1 , wherein depositing the counter electrode layer comprises depositing the counter electrode layer to a thickness of between about 150 nm and about 350 nm.
9. The method of claim 1 , wherein the ratio of thicknesses of the electrochromic layer to the counter electrode layer is between about 1.7:1 and 2.3:1.
10. The method of claim 1 , wherein depositing the counter electrode layer comprises depositing nickel tungsten oxide at a pressure of between about 1 mTorr and about 50 mTorr.
11. The method of claim 1 , further comprising depositing a layer of transparent conductive oxide on the stack.
12. The method of claim 1 , wherein the substrate comprises architectural glass.
13. The method of claim 1 , wherein the substrate is in the substantially vertical orientation during translational and linear movement between multiple deposition stations in the integrated vacuum deposition system.
14. The method of claim 1 , wherein each of the sequentially deposited layers is deposited at a different deposition station of the multiple deposition stations.
15. The method of claim 1 , wherein the multiple deposition stations of the single integrated vacuum deposition system operate in a controlled environment.
16. The method of claim 3 , further comprising depositing lithium on at least one of the tungsten oxide electrochromic layer, the inorganic and solid lithium ion conducting layer and the nickel tungsten oxide counter electrode layer.