Electrochromic multi-layer devices with composite current modulating structure
A multi-layer device comprising a first substrate, a first electrically conductive layer and a first current modulating structure on a surface thereof, the first current modulating structure comprising a composite of a resistive material and a patterned insulating material, the first current modulating structure having a cross-layer resistance to the flow of electrical current through the first current modulating structure that varies as a function of position.
1. A method for controlling an electrochromic device, comprising:
providing an electrochromic device, comprising:
a first substrate comprising a surface;
a first electrically conductive layer on the surface of the first substrate, the first electrically conductive layer comprising a resistance to current flow substantially parallel to a major surface of the first electrically conductive layer that varies as a function of position;
a second substrate comprising a surface;
a second electrically conductive layer on the surface of the second substrate, the second electrically conductive layer comprising a resistance to current flow substantially parallel to a major surface of the second electrically conductive layer that varies as a function of position;
an electrochromic stack comprising:
a first electrode layer in electrical contact with the first electrically conductive layer;
a second electrode layer in electrical contact with the second electrically conductive layer; and
an ion conductor layer, wherein the first electrode layer is on one side of and in contact with a first surface of the ion conductor layer, and the second electrode layer is on the other side of and in contact with a second surface of the ion conductor layer;
a first bus bar in electrical contact with a perimeter edge of the first electrically conductive layer; and
a second bus bar in electrical contact with a perimeter edge of the second electrically conductive layer that is opposite the perimeter edge of the first electrically conductive layer; and
applying a voltage pulse to the first and second bus bars of the electrochromic device to switch the electrochromic device from a first to a second optical state having differing transmissivities;
wherein a local voltage across the electrochromic stack may be significantly less than the applied voltage pulse.
2. The method of claim 1 , wherein the first electrically conductive layer is patterned.
3. The method of claim 2 , wherein the second electrically conductive layer is patterned.
4. The method of claim 1 , wherein:
the first electrically conductive layer further comprises one or more of a composition that varies as a function of position, a thickness that varies as a function of position, and a defect density that varies as a function of position.
5. The method of claim 4 , wherein:
the second electrically conductive layer further comprises one or more of a composition that varies as a function of position, a thickness that varies as a function of position, and a defect density that varies as a function of position.
6. The method of claim 1 , wherein the first and second electrically conductive layers comprise indium tin oxide and a transparent conductive material comprising doped tin oxide.
7. The method of claim 1 , wherein a ratio of the resistance to current flow substantially parallel to the major surface of the first electrically conductive layer in a first region of the first electrically conductive layer circumscribed by a first convex polygon to the resistance to current flow substantially parallel to a major surface of the first electrically conductive layer in a second region of the first electrically conductive layer circumscribed by a second convex polygon is at least 2, the first and second regions circumscribed by the first and second convex polygons, respectively, each comprising at least 25% of the major surface of the first electrically conductive layer.
8. The method of claim 7 , wherein a ratio of the resistance to current flow substantially parallel to the major surface of the second electrically conductive layer in a first region of the second electrically conductive layer circumscribed by a first convex polygon to the resistance to current flow substantially parallel to the major surface of the second electrically conductive layer in a second region of the second electrically conductive layer circumscribed by a second convex polygon is at least 2, the first and second regions circumscribed by the first and second convex polygons, respectively, each comprising at least 25% of the major surface of the second electrically conductive layer.
9. The method of claim 1 , wherein the resistance to current flow substantially parallel to a major surface of the first and second electrically conductive layers provide a uniform potential drop across the area of the electrochromic stack.
10. The method of claim 1 , wherein the resistance to current flow substantially parallel to a major surface of the first and second electrically conductive layers provide a desired non-uniform potential drop across the area of the electrochromic stack.
11. The method of claim 1 , wherein the first and second substrates are transmissive to electromagnetic radiation having a wavelength in the range of infrared to ultraviolet.
12. The method of claim 1 , further comprising forming the first and second electrode layers using sol-gel deposition processes, wherein the first and second electrode layers comprise electrochromic materials comprising oxides.
13. The method of claim 1 , wherein the first or the second electrode layer comprises an electrochromic material comprising cathodically coloring thin films comprising oxides based on tungsten, molybdenum, niobium, titanium, lead, bismuth, or combinations thereof, or anodically coloring thin films comprising oxides, hydroxides or oxy-hydrides based on nickel, iridium, iron, chromium, cobalt, rhodium, or combinations thereof.
14. The method of claim 1 , wherein:
the first electrode layer comprises an electrochromic material comprising cathodically coloring thin films comprising oxides based on tungsten, molybdenum, niobium, titanium, lead, bismuth, or combinations thereof; and
the second electrode layer comprises an electrochromic material comprising anodically coloring thin films comprising oxides, hydroxides or oxy-hydrides based on nickel, iridium, iron, chromium, cobalt, rhodium, or combinations thereof.
15. The method of claim 1 , wherein the first or the second electrode layer comprises an electrochromic material comprising tungsten oxide, molybdenum oxide, niobium oxide, titanium oxide, copper oxide, iridium oxide, chromium oxide, manganese oxide, vanadium oxide, nickel oxide, cobalt oxide, or combinations thereof.
16. The method of claim 1 , wherein the ion conductor layer is an organic ion conductor layer, and the method further comprises forming the organic ion conductor layer by processes employing liquid components.