Fabrication of electrochromic devices
Electrochromic devices and methods may employ the addition of a defect-mitigating insulating layer which prevents electronically conducting layers and/or electrochromically active layers from contacting layers of the opposite polarity and creating a short circuit in regions where defects form. In some embodiments, an encapsulating layer is provided to encapsulate particles and prevent them from ejecting from the device stack and risking a short circuit when subsequent layers are deposited. The insulating layer may have an electronic resistivity of between about 1 and 10 8 Ohm-cm. In some embodiments, the insulating layer contains one or more of the following metal oxides: aluminum oxide, zinc oxide, tin oxide, silicon aluminum oxide, cerium oxide, tungsten oxide, nickel tungsten oxide, and oxidized indium tin oxide. Carbides, nitrides, oxynitrides, and oxycarbides may also be used.
1. A method of fabricating an electrochromic device, the method comprising:
forming an electrochromic stack on a first electrode layer disposed on a substrate and forming a second electrode layer over the electrochromic stack, wherein the electrochromic stack comprises an electrochromic layer of electrochromic material and a counter electrode layer of counter electrode material, and wherein the first electrode layer comprises a first transparent electronically conductive material and the second electrode layer comprises a second transparent electronically conductive material; and
depositing a defect-mitigating insulating layer to seal a pop-off defect in the electrochromic device stack;
wherein the defect-mitigating insulating layer comprises a substantially transparent and electronically insulating material, and
further comprising introducing lithium metal into the electrochromic stack, wherein the defect-mitigating insulating layer is deposited after the introduction of lithium metal.
2. The method according to claim 1 , wherein depositing the defect-mitigating insulating layer prevents electronically conducting layers and/or electrochromically active layers of the device from contacting layers of the opposite polarity and creating a short circuit in the region of the pop-off defect.
3. The method according to claim 1 comprising depositing the defect-mitigating insulating layer in a process operation after the execution of a process operation that has a propensity to cause ejection of particles from the electrochromic stack.
4. The method according to claim 3 , wherein the process operation in which the defect-mitigating insulating layer is deposited is the next operation after the process operation that has a propensity to cause ejection of particles from the electrochromic stack.
5. The method according to claim 1 , wherein the defect-mitigating insulating layer is a metal oxide, a metal nitride, a metal carbide, a metal oxynitride, or a metal oxycarbide.
6. The method according to claim 1 , wherein the defect-mitigating insulating layer is selected from the group consisting of:
(a) cerium oxide, titanium oxide, aluminum oxide, zinc oxide, tin oxide, silicon aluminum oxide, tungsten oxide, nickel tungsten oxide, tantalum oxide, and oxidized indium tin oxide;
(b) titanium nitride, aluminum nitride, silicon nitride, tungsten nitride;
(c) titanium carbide, aluminum carbide, silicon carbide, tantalum carbide, and tungsten carbide; or
(d) silicon oxynitride.
7. The method according to claim 1 , wherein the defect-mitigating insulating layer is between about 5 nm and 500 nm thick.
8. The method according to claim 1 , wherein the defect-mitigating insulating layer is between about 10 nm and 100 nm thick.
9. The method of claim 1 , wherein depositing the defect-mitigating insulating layer is performed after forming at least part of the electrochromic layer of the counter electrode layer, whichever is performed last.
10. The method of claim 1 , wherein an electrical resistivity of the defect-mitigating insulating layer is between the electrical resistivity of a conventional ion conducting layer and the electrical resistivity of the first or the second transparent electronically conductive material.
11. The method of claim 1 , wherein an electrical resistivity of the defect-mitigating insulating layer is different from the electrical resistivity of the electrochromic layer or the counter electrode layer by less than an order of magnitude.