Electrochromic multi-layer devices with current modulating structure
View Patent ↗A multi-layer device comprising a first substrate, a first electrically conductive layer on a surface thereof, and a first current modulating layer, the first electrically conductive layer having a sheet resistance to the flow of electrical current through the first electrically conductive layer that varies as a function of position.
1. An electrochromic device comprising a first substrate, a first electrically conductive layer, a first current modulating structure, a first electrode layer, a second electrically conductive layer and a second substrate, the electrically conductive layer and the first current modulating structure each covering at least 0.01 m 2 of the surface of the first substrate, the first current modulating structure being between the first electrically conductive layer and the first electrode layer, the first current modulating structure comprising a material having a resistivity of at least 10 4 Ω·cm, the first electrically conductive layer having a sheet resistance, R s , to the flow of electrical current through the first electrically conductive layer that varies as a function of position in the first electrically conductive layer, wherein a first contour map of the sheet resistance, R s , as a function of position within the first electrically conductive layer contains a first set of isoresistance lines and a first set of resistance gradient lines normal to the first set of isoresistance lines; and the sheet resistance along a gradient line in the first set of gradient lines generally increases, generally decreases, generally increases until it reaches a maximum and then generally decreases, or generally decreases until it reaches a minimum and then generally increases.
2. The electrochromic device of claim 1 , further comprising first and second busbars respectively coupled to the first and second electrically conductive layers wherein (i) the first and second busbars are configured to receive a drive current I DRV to enable a current driven mode for switching the electrochromic device to a target optical state with respect to a minimum optical state and a maximum optical state thereof; (ii) the electrochromic device comprises a total charge capacity having a total charge Q TOT ; (iii) the target optical state is attainable by charging the electrochromic device to a target charge Q TGT via the drive current I DRV , the target charge Q TGT comprises a percentage of the total charge Q TOT corresponding to a percentage of the target optical state relative to the maximum optical state; and (iv) the target optical state is predictably attainable for substantially all of a total optically switchable area of the electrochromic device, and within a target time T TGT , by adjustment of the drive current I DRV such that the product of the target time T TGT and the drive current I DRV substantially equals the target charge Q TGT .
3. The electrochromic device of claim 2 , wherein the optically switchable area of the electrochromic device is transitionable to the target optical state once the drive current I DRV is adjusted to a constant current value corresponding to the target time T TGT .
4. The electrochromic device of 1 wherein (i) the ratio of the average sheet resistance in a first region of the first electrically conductive layer circumscribed by a first convex polygon to the average sheet resistance 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 of the first electrically conductive layer each comprising at least 25% of the surface area of the first electrically conductive layer and (ii) the ratio of the average sheet resistance in a first region of the second electrically conductive layer circumscribed by a first convex polygon to the average sheet resistance 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 of the second electrically conductive layer each comprising at least 25% of the surface area of the second electrically conductive layer.
5. The electrochromic device of claim 1 wherein the second electrically conductive layer has a spatially varying sheet resistance, R s , that varies as a function of position in the second electrically conductive layer, a second contour map of the sheet resistance, R s , as a function of position within the second electrically conductive layer contains a second set of isoresistance lines and a second set of resistance gradient lines normal to the second set of isoresistance lines, and the sheet resistance along a gradient line in the second set of gradient lines generally increases, generally decreases, generally increases until it reaches a maximum and then generally decreases, or generally decreases until it reaches a minimum and then generally increases.
6. The electrochromic device of claim 1 wherein the first and second substrate and the first and second electrically conductive layer are transparent to electromagnetic radiation having a wavelength in the range of infrared to ultraviolet.
7. The electrochromic device of claim 1 wherein the electrochromic device comprises, in succession, the first substrate, the first electrically conductive layer, the first current modulating structure, the first electrode layer, an ion conducting layer, a second electrode layer, the second electrically conductive layer and the second substrate.
8. The electrochromic device of claim 1 wherein the first electrically conductive layer comprises a first material and a second material, the first material being a transparent conductive oxide and the second material having a resistivity that is greater than the resistivity of the first material by a factor of at least 10 2 .
9. The electrochromic device of claim 1 wherein the first current modulating structure comprises a resistive material selected from the group consisting of zinc oxide, zinc sulfide, titanium oxide, and gallium (III) oxide, yttrium oxide, zirconium oxide, aluminum oxide, indium oxide, stannic oxide and germanium oxide.
10. The electrochromic device of claim 1 wherein the first current modulating structure comprises an insulating material selected from a group consisting of alumina, silica, porous silica, fluorine doped silica, carbon doped silica, silicon nitride, silicon oxynitride, hafnia, magnesium fluoride, magnesium oxide, poly(methyl methacrylate) (PMMA), polyimides, polymeric dielectrics such as polytetrafluoroethylene (PTFE) and silicones.
11. A process for the preparation of a multi-layer device comprising forming a multi-layer layer structure comprising an electrochromic layer between and in electrical contact with a first and a second electrically conductive layer, and a first current modulating structure between the first electrically conductive layer and the electrochromic layer, the first current modulating structure comprising a material having a resistivity of at least 10 4 Ω·cm, the first and/or the second electrically conductive layer having a spatially varying sheet resistance, R s , to the flow of electrical current through the first and/or the second electrically conductive layer that varies as a function of position in the first and/or the second electrically conductive layer, respectively, wherein a contour map of the sheet resistance, R s , as a function of position within the first or the second electrically conductive layer contains a set of isoresistance lines and a set of resistance gradient lines normal to the isoresistance lines, and the sheet resistance along a gradient line in the set generally increases, generally decreases, generally increases until it reaches a maximum and then generally decreases, or generally decreases until it reaches a minimum and then generally increases.
12. The process of claim 11 wherein the first electrically conductive layer comprises a first material and a second material, the first material being a transparent conductive oxide and the second material having a resistivity that is greater than the resistivity of the first material by a factor of at least 10 2 .
13. The process of claim 11 wherein the first current modulating structure comprises a resistive material selected from the group consisting of zinc oxide, zinc sulfide, titanium oxide, and gallium (III) oxide, yttrium oxide, zirconium oxide, aluminum oxide, indium oxide, stannic oxide and germanium oxide.
14. The process of claim 11 wherein the first current modulating structure comprises an insulating material selected from a group consisting of alumina, silica, porous silica, fluorine doped silica, carbon doped silica, silicon nitride, silicon oxynitride, hafnia, magnesium fluoride, magnesium oxide, poly(methyl methacrylate) (PMMA), polyimides, polymeric dielectrics such as polytetrafluoroethylene (PTFE) and silicones.
15. The process of claim 11 further comprising laser patterning a series of scribes into the first and/or the second electrically conductive layer, wherein the first and/or the second electrically conductive layer comprises a constant thickness and constant resistivity film prior to laser patterning.
16. The process of claim 11 further comprising introducing a dopant variation into the first and/or the second electrically conductive layer.
17. The process of claim 11 further comprising introducing a thickness variation into the first and/or the second electrically conductive layer.
18. The process of claim 11 further comprising depositing the first and/or the second electrically conductive layer using sputter coating.
19. The process of claim 11 further comprising depositing the first current modulating structure using sol-gel deposition.
20. The process of claim 11 wherein the electrochromic layer comprises one or more electrochromic electrodes, and the electrochromic electrodes are deposited using sol-gel deposition.