Fabrication of low defectivity electrochromic devices
View Patent ↗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. An electrochromic window comprising:
(a) an architectural glass substrate; and
(b) a electrochromic stack disposed on said substrate, the stack comprising a tungsten oxide electrochromic layer and a nickel tungsten oxide counter electrode layer;
wherein the electrochromic window has fewer than about 0.045 total visible defects per square centimeter in any region of electrochromic active area.
2. The electrochromic window of claim 1 , wherein the electrochromic layer comprises WO x , wherein x is less than 3.0 and at least 2.7.
3. The electrochromic window of claim 1 , wherein the tungsten oxide has a substantially nanocrystalline morphology.
4. The electrochromic window of claim 1 , wherein the electrochromic layer has a thickness of between about 200 nm and about 700 nm.
5. The electrochromic window of claim 1 , wherein the electrochromic layer and the counter electrode layer each comprise lithium ions.
6. The electrochromic window of claim 1 , wherein the counter electrode layer has a thickness of between about 150 nm and about 350 nm.
7. The electrochromic window 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.
8. The electrochromic window of claim 1 , further comprising a first layer of transparent conductive oxide in electrical contact with the electrochromic layer and a second layer of transparent conductive oxide in electrical contact with the counter electrode layer.
9. The electrochromic window of claim 8 , wherein each layer of transparent conductive oxide has a sheet resistance of between about 5 ohms/square and about 30 ohms/square.
10. The electrochromic window of claim 9 , wherein each layer of transparent conductive oxide has substantially the same sheet resistance.
11. The electrochromic window of claim 1 , comprising fewer than about 0.04 visible pinhole defects per square centimeter of the electrochromic window.
12. The electrochromic window of claim 1 , comprising fewer than about 0.005 visible short-type defects per square centimeter of the electrochromic window.
13. The electrochromic window of claim 1 , comprising a number of non-visible short-type defects that produce a leakage current of less than about 5 μA/cm 2 at ±2V bias of the electrochromic window.