WO2022208161A1

WO2022208161A1 - Electrochromic device containing an optically transparent silver layer and an electrically conductive, optically transparent oxide layer, and method of forming the same

Info

Publication number: WO2022208161A1
Application number: PCT/IB2022/000136
Authority: WO
Inventors: Scott Thomsen; Guillermo Garcia; Andrew Loxley
Original assignee: Heliotrope Europe S.L.
Priority date: 2021-03-31
Filing date: 2022-03-16
Publication date: 2022-10-06

Abstract

An article includes a transparent substrate, an electrode, an optically transparent silver layer located between the transparent substrate and the electrode, an electrically conductive transparent conductor bridge layer located between the silver layer and the electrode, an electrically conductive thermal and mechanical protection layer located between tire silver layer and the transparent conductor bridge layer, and an electrically conductive capping layer located between the electrode and the transparent conductor bridge layer. The article may be used in an electrochromic device.

Description

ELECTROCHROMIC DEVICE CONTAINING AN OPTICALLY TRANSPARENT SILVER LAYER AND AN ELECTRICALLY CONDUCTIVE, OPTICALLY TRANSPARENT OXIDE LAYER,

AND METHOD OF FORMING THE SAME

RELATED APPLICATION

[0001] This present application claims the benefit of priority from U.S. Provisional Patent Application Serial No. 63/168,853 filed on March 31, 2021, and the entire contents of which is incorporated herein by reference

FIELD

[0002] The present invention is generally directed to electrochromic devices, and more particularly to an electrochromic device containing a silver transparent conductor and method of making thereof,

BACKGROUND

[0003] An electrochromic (EC) window undergoes a reversible change in optical properties when driven by an applied potential. Some EC devices may include a working electrode, a solid state electrolyte, and a counter electrode sandwiched between two transparent conductor layers and outer glass layers.

SUMMARY

[0004] According to an embodiment of the present disclosure, an article includes a transparent substrate, an electrode, an optically transparent silver layer located between the transparent substrate and the electrode, an electrically conductive transparent conductor bridge layer located between the silver layer and the electrode, an electrically conductive thermal and mechanical protection layer located between the silver layer and the transparent conductor bridge layer, and an electrically conductive capping layer located between the electrode and the transparent conductor bridge layer.

[0005] According to another embodiment of the present disclosure, an electrochromic device (EC device) comprises a first transparent substrates, a second transparent substrate, a working electrode located between the first and the second transparent substrates, a counter electrode located between the first and the second transparent substrates, an electrolyte located between the working electrode and the counter electrode, a first layer stack located between the first transparent substrate and the working electrode, and a second layer stack located between the second transparent substrate and the counter electrode. The first layer stack comprises a first transparent conductor comprising an optically transparent first silver layer, and at least one electrically conductive, optically transparent first oxide layer located between the optically transparent silver layer and the working electrode.

[0006] According to another embodiment of the present disclosure, a method comprises forming an electrically conductive and optically transparent silver layer over a transparent substrate, forming an electrically conductive thermal and mechanical protection layer over the silver layer, forming an electrically conductive transparent conductor bridge layer over the thermal and mechanical protection layer, forming an electrically conductive capping layer over the transparent conductor bridge layer, and forming a first electrode over the capping layer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is a schematic side cross sectional view of an electrochromic (EC) de vice according to various embodiments.

[0008] FIG. 2 is close up side cross sectional view of a layer stack containing a silver transparent conductor according to various embodiments.

[0009] FIG. 3 is close up side cross sectional view of the electrochromic device including the layer stacks containing tire respective silver transparent conductors according to various embodiments.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0010] FIG. 1 illustrates one embodiment of an EC device. It should be noted that such electrochromic devices may be oriented upside down or sideways from the orientations illustrated in FIG. 1. Furthermore, the thickness of the layers and/or size of the components of the device in FIG. 1 are not drawn to scale or in actual proportion to one another other, but rather are shown as representations. [0011] In FIG. 1, an embodiment electroehromic device 100 may include a first transparent conductor layer 102a, a working electrode 104, a solid state electrolyte 106, a counter electrode 108, and a second transparent conductor layer 102b. Some embodiment electroehromic devices may also include one or more optically transparent layers, such as a transparent layer 110a positioned in front of the first transparent conductor layer 102a and/or a transparent layer IT 0b positioned behind the second transparent conductor layer 102b. The transparent layers 110a, 110b may be formed of transparent materials, such as plastic or glass.

[0012] The first and second transparent conductor layers 102a, 102b may be formed from transparent conducting films fabricated using inorganic and/or organic materials. For example, the transparent conductor layers 102a, 102b may include inorganic films of transparent conducting oxide (TCO) materials, such as indium tin oxide (ITO) or fluorine doped tin oxide (FTO). In other examples, organic films in transparent conductor layers 102a, 102b may include graphene and/or various polymers.

[0013] In the various embodiments, the working electrode 104 may include nanostructures 112 of a doped or undoped transition metal oxide bronze, and optionally nanostructures 113 of a transparent conducting oxide (TCO) composition shown schematically as circles and hexagons for illustration purposes only. As discussed above, the thickness of the layers of the device 100, including and the shape, size and scale of nanostructures i s not dra wn to scale or in actual proportion to each other, but is represented for clarity. In the various embodiments, nanostructures 112, 113 may be embedded in an optically transparent matrix material or provided as a packed or loose layer of nanostructures exposed to the electrolyte.

[0014] In the various embodiments, the doped transition metal oxide bronze of nanostructures 112 may be a ternary composition of the type AxMzOy, where M represents a transition metal ion species in at least one transition metal oxide, and A represents at least one dopant. Transition metal oxides that may be used in the various embodi ments include, but are not limited to any transition metal oxide which can be reduced and has multiple oxidation states, such as niobium oxide, tungsten oxide, molybdenum oxide, vanadium oxide, titanium oxide and mixtures of two or more thereof. In one example, the nanostructured transition metal oxide bronze may include a plurality of tungsten oxide (W(¾-_x) nanoparticles, where 0 < x < 1 , such as 0 < x < 0.8, or lithium tungsten oxide nanoparticles. [0015] In various embodiments, nanostructures 113 may optionally be mixed with the doped transition metal oxide bronze nanostructures 112 in the working electrode 104. In the various embodiments, the nanostructures 113 may include at least one TCO composition, which prevents UV radiation from reaching the electrolyte and generating electrons. In an example embodiment, the nanostructures 113 may include an indium tin oxide (ITO) composition, which may be a solid solution of around 60-95 wt% (e.g., 85-90 wt%) indium(III) oxide (InaQj) and around 5-40 wt% (e.g., 10-15 wt%) tin(IV) oxide (SnCh). In another example embodiment, the nanostructures 113 may include an aluminum-doped zinc oxide (AZO) composition, which may be a solid solution of around 99 wt% zinc oxide (ZnO) and around 2 wt% aluminum(HT) oxide (AI2O3). Additional or alternative TCO compositions that may be used to form nanostructures 113 in the various embodiments include, but are not limited to, indium oxide, zinc oxide and other doped zinc oxides such as gallium-doped zinc oxide and indium-doped zinc oxide.

[0016] The nanostructures 112 and optional nanostructure 113 of the working electrode may modulate transmittance of visible radiation as a function of applied voltage and/or current by operating in two different modes. For example, a first mode may be a highly solar transparent (“bright”) mode in which the working electrode 104 is transparent to NIR radiation and visible light radiation. A second mode may be a visible blocking (“dark” ) mode in which the working electrode 104 absorbs radiation in the visible spectral region and at least a portion of the NIR spectral region. In an example, application of a first voltage having a negative bias may cause the electrochromic device to operate in the dark mode, blocking transmittance of visible and NIR radiation at wavelengths of around 780-2500 mil. In another example, application of a second voltage having a positive bias may cause the electrochromic device to operate in the bright mode, allowing transmittance of radiation in both the visible and NIR spectral regions. In various embodiments, the applied voltage may be between -2V and 2V. For example, the first voltage may be -2V, and the second voltage may be 2V.

[0017] Optionally, the nanostructures 112 and/or 113 may be embedded in a matrix and/or capped by a capping layer. For example, the capping layer may comprise a metal oxide material, such as niobium oxide or lithium niobate, and the matrix may comprise an ionically conductive and electrically insulating lithium rich antiperovskite (LiRAP) material, as described in U.S. Patent Number 10,698,287 B2, incorporated herein by reference in its Attorney Docket No. 2000-028WO entirety. The LiRAP material may have a formula Li3OX, where X is F, Cl, Br, I, or any combination thereof. For example, the LiRAP material may comprise Li3OI. [0018] In various embodiments, the solid state electrolyte 106 may include at least a polymer material and an optional plasticizer material. The term “solid state,” as used herein with respect to the electrolyte 106, refers to a polymer-gel and/or any other non-liquid material. In some embodiments, the solid state electrolyte 106 may further include a salt containing, for example, an ion species selected from the group of lanthanides (e.g., cerium, lanthanum, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium), alkali metals (e.g., lithium, sodium, potassium, rubidium, and cesium), and alkali earth metals (e.g., beryllium, magnesium, calcium, strontium, and barium). In an example embodiment, such salt in the solid state electrolyte 106 may contain a lithium and/or sodium ions. Polymers that may be part of the electrolyte 106 may include, but are not limited to, poly(methyl methacrylate) (PMMA), poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate) (PVB), poly(ethylene oxide) (PEO), polyurethane acrylate, fluorinated co-polymers such as poly(vinylidene fluoride-co- hexafluoropropylene), poly(acrylonitrile) (PAN), poly(vinyl alcohol) (PVA), etc. Plasticizers that may be part of the polymer electrolyte formulation include, but are not limited to, glymes (tetraglyme, triglyme, diglyme etc.), propylene carbonate, ethylene carbonate, ionic liquids (1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium bis(trifluoromethane sulfonyl) imide, 1- butyl-1-methyl-pyrrolidinium bis(trifluoromethane sulfonyl)imide, etc.), N,N- dimethylacetamide, and mixtures thereof. [0019] The counter electrode 108 of the various embodiments should be capable of storing enough charge to sufficiently balance the charge needed to cause visible tinting to the nanostructured transition metal oxide bronze in the working electrode 104. In various embodiments, the counter electrode 108 may be formed as a conventional, single component film, a nanostructured film, or a nanocomposite layer. [0020] In some embodiments, the counter electrode 108 may be formed from at least one passive material that is optically transparent to both visible and NIR radiation during the applied biases. Examples of such passive counter electrode materials may include CeO2, CeVO2, TiO2, indium tin oxide, indium oxide, tin oxide, manganese or antimony doped tin oxide, aluminum doped zinc oxide, zinc oxide, gallium zinc oxide, indium gallium zinc 5 oxide, molybdenum doped indium oxide, Fe₂O₃, and/or V₂O_5. In other embodiments the counter electi'ode 108 may be formed from at least one complementary material, which may be transparent to N1R radiation but which may be oxidized in response to application of a bias, thereby causing absorption of visible light radiation. Examples of such complementary counter electrode materials may include Ci'203, MnCh, FeCb, C0O2, NiCk, RhCte, or Ir02.

The counter electrode materials may include a mixture or discrete sublayers of one or more passive materials and/or one or more complementary materials described above.

[0021] Optionally, the counter electrode 108 may include nanostructures of one or more passive materials and/or one or more complementary materials described above embedded in a matrix and/or capped by a capping layer. For example, the capping layer may comprise a metal oxide material, such as niobium oxide or lithium niobate, and the matrix may comprise the LiRAP material.

[0022] FIG. 2 illustrates an article 150 which may comprise a portion of the EC device 100 during manufacture. The article 150 includes the transparent substrate (110a or 110b), such as a glass substrate, and an electrode, such as the working electrode 104 or the counter electrode 108. The article 150 also includes a layer stack 116 located between the transparent substrate (110a or 110b) and the electrode (104 or 108). The layer stack 116 includes the transparent conductor (102a or 102b) and an insulating layer stack 118 located between the transparent substrate (110a or ! 10b) and the transparent conductor (102a or 102b). The layer stack 116 is optically transparent such that is transmits at least 70 percent, such as at least 80 percent, for example 80 to 99 percent Divisible light (e.g,, having a wavelength of 400 nm to 700 nm) therethrough. Therefore, ail layers of the layer stack 116 are optically transparent.

[0023] The layer stack 116 is formed by forming the insulating layer stack 118 on the transparent substrate (110a or 110b) and then forming the transparent conductor (102a or 102b) on the insulating layer stack 118. The insulating layer stack 118 may be formed by forming an electrically insulating diffusion barrier and optical interface layer 120 over the transparent substrate (110a or 110b), forming an electrically insulating index matching layer 122 over the diffusion barrier and optical interface layer 120, and forming an electrically insulating seed layer 124 over the index matching layer 122.

[0024] The transparent conductor (102a or 102b) may be formed by forming an electrically conductive and optically transparent silver layer 126 over the transparent substrate (e.g., on the seed layer 124), forming an electrically conductive thermal and mechanical protection layer 128 over the silver layer 126, formi ng an electrically conductive transparent conductor bridge layer 130 over the thermal and mechanical protection layer 128, and forming an electrically conductive capping layer 132 over the transparent conductor bridge layer 130. A first electrode (104 or 108) is formed over the capping layer 132.

[0025] The layers of the layer stack 116 may be formed by sequentially sputtering the electrically insulating layers of the insulating layer stack 118 on the transparent substrate (110a or 110b) followed by sequentially sputtering the electrically conductive layers of the transparent conductor (102a or 102b) on the insulating layer stack 118 while the transparent substrate (110a or 110b) continuously moves through different sputtering chambers. After forming the electrically insulating layers and the electrically conductive layers of the layer stack 116 over the transparent substrate (110a or 110b), the layer stack 116 may be cured by annealing at a temperature above 350 degrees Celsius, such as 375 to 450 degrees Celsius, for example 400 to 425 degrees Celsius for 10 minutes to 1 hour. The thermal and mechanical protection layer 128 prevents or reduces flow of the silver layer 126 during the curing step.

In one embodiment, the silver layer 126 may be formed on the seed layer 124 by sputtering silver from a silver target in an argon and hydrogen plasma to increase the stability of the silver layer during the layer stack 116 curing process. The curing process may be conducted before or after forming the electrode (104 or 108).

[0026] If the transparent substrate (110a or 110b) comprises a glass substrate, such as a float glass substrate, then it may be heat tempered at a temperature above 500 degrees Celsius, such as 550 to 650 degrees Celsius, such as 600 to 625 degrees Celsius, after forming the layer stack 116 and the electrode (104 or 108). The heat tempering may last for 30-120 minutes, after which the article 150 may be quenched or cooled. For example, quenching may include cooling the article to temperatures under 100° C using liquid or gas (e.g. water or air quenching) for a period on the order of seconds (e.g. 5-15 seconds). The layer stack 116 and the electrode (104 or 108) comprise post temperable layers with properties which are not significantly negatively affected or are enhanced by the tempering process.

[0027] The transparent substrate (110a or 110b) may also be shaped (e.g., bent or curved such that it has a concave and/or convex major surface) during the tempering and/or during another heat treatment after forming the layer stack 116 and the electrode (104 or 108). For example, the transparent substrate (110a or 110b) may be shaped in a mold or by another technique at an elevated temperature into a shape that may be used in a window or sunroof of a vehicle. A vehicle may be a ground based vehicle, such as automobile, mass transit vehicle, train, track, etc., a water based vehicle, such as a boat, or an air based vehicle, such as airplane or helicopter. Such widows and sunroofs typically have a convex outer surface which curves outward from the interior of the vehicle.

[0028] Thus, the article 150 includes a transparent substrate (110a or 110b), an electrode (104 or 108), and the transparent conductor (102a or 102b) comprising an optically transparent silver layer 126 located between the transparent substrate (110a or 110b) and the electrode (104 or 108), an electrically conductive transparent conductor bridge layer 130 located between the silver layer 126 and the electrode (104 or 108), an electrically conducti ve thermal and mechanical protection layer 128 located between the silver layer 126 and the transparent conductor bridge layer 130, and an electrically conductive capping layer 132 located between the electrode (104 or 108) and the transparent conductor bridge layer 130.

[0029] In one embodiment, the silver layer 126 has a thickness of 5 to 11 nm, for example 8 to 10 nm. Therefore, the silver layer 126 is sufficiently thin to be optically transparent.

The silver layer 126 increases the conductivity of the transparent conductor (102a or 102b) compared to a transparent conductor which contains only a transparent conductive oxide material. The silver layer 126 also has a low thermal emissivity and controls the heat gain of the article 150 (e.g., transmits at least 70% of the visible light, but blocks a significant amount of infrared radiation (i.e,, heat)). When the article 150 containing the silver layer 126 is incorporated into an eiectroehromic device 100, the eiectroehromic device may be switched at a faster switching speed due to the increased conductivity of the silver layer while reducing the heat gain due to the low emissivity of the silver layer 126. For example, the transparent conductor 102a or 102b containing the silver layer 126 may have sheet resistance of about 3 to about 5 Ohm/sq, such as about 3.4 to about 4 Ohm/sq, to provide a faster switching.

[0030] In one embodiment, the silver layer 126 may have a predominant (111) crystalline out of plane orientation which improves its electrical properties and its hemispherical emittance. For example, the silver layer 126 may have a predominant [111] crystalline direction in the major surfaces contacting the seed layer 124 and the thermal and mechanical protection layer 128. As used herein, a predominant plane or direction in a surface means that at least 50 percent of the surface has the specified crystalline plane or normal crystalline direction to the surface. The silver layer 126 may have a refractive index (“n”) of between 1.2 and 1.22, such as about 1.21.

[0031] The thermal and mechanical protection layer 128 may have a thickness of 1 to 4 ran, such as 1 to 3 nm. The thermal and mechanical protection layer 128 may comprise nickel chromium oxide or titanium oxide, in one embodiment, the thermal and mechanical protection layer 128 comprises the nickel chromium oxide containing 20 to 40, such as 29 to 35 atomic percent nickel, 5 to 15, such as 7 to 10 atomic percent chromium, and 45 to 75, such as 64 to 70 atomic percent oxygen.

[0032] In one embodiment, the nickel chromium oxide has a graded composition as a function of thickness comprising a lower oxygen concentration at a bottom surface contacting the silver layer 126 than at a top surface contacting the first transparent conductor bridge layer 130. The graded composition may he formed by reactive sputtering using plural metal (i.e., separate Ni and Cr and/or NiCr alloy (e.g., 80:20 to 70:30 ratio Ni:Cr alloy) sputtering targets, and providing a higher oxygen flow (e.g., at least 10 seem higher) to the downstream target than to the upstream target while the transparent substrate (110a or 110b) moves past the sputtering targets in a direction from the upstream target to the downstream target. The lower oxygen concentration in the lower surface improves the ability of the thermal and mechanical protection layer 128 to reduce or eliminate silver layer 126 agglomeration during the curing and/or tempering processes. The higher oxygen concentration in the upper surface improves the adhesion of the transparent conductor bridge layer 130 to the thermal and mechanical protection layer 128.

[0033] The transparent conductor bridge layer 130 may have a thickness of 80 to 120 nm, such as 85 to 110 nm. The relatively thick transparent conductor bridge layer 130 is a structural electrically conductive layer which increases the layer stack 116 conductivity, protects the silver layer 126 from corrosion, and permits the silver layer 126 to be relatively thin and/or only a single silver layer 126 to he used in the layer stack 116. This improves the visible light transmissivity of the layer stack 116 and permits the use of a thinner index matching layer 122 and improves the index of refraction matching between the layers of the layer stack 116. [0034] The transparent conductor bridge layer 130 may comprise indium tin oxide or a bilayer of tin oxide and indium tin oxide. If the bilayer is used, then the tin oxide sublayer is located on the thermal and mechanical protection layer 128 and the indium tin oxide sublayer is located on the tin oxide sublayer. The tin oxide sublayer may have a thickness of 5 to 40 nm, such as 20 to 40 nm, and the indium tin oxide sublayer may have a thickness of 70 to 105 nm, such as 70 to 90 nm. In one embodiment, the transparent conductor bridge layer 130 comprises indium tin oxide containing 35 to 50, such as 42 to 45 atomic percent indium, 5 to 15, such as 8 to 10 atomic percent tin, and 35 to 60, such as 50 to 55 atomic percent oxygen, to improve the layer durability during the curing process. The transparent conductor bridge layer 130 may have a refractive index of about 2 to 2.25, such as about 2.18 and sheet resistance between I I and 13 Ohm/sq, such as about 12 Ohm/sq.

[0035] In one embodiment, the transparent conductor bridge layer 130 comprises the indium tin oxide having a graded composition as a function of thickness comprising a lower oxygen concentration at a bottom surface contacting the thermal and mechanical protection layer 128 than at a top surface contacting the capping layer 132. The indium tin oxide layer may be formed as a metallic indium and tin containing layer at room temperature, followed by oxidation by annealing it in an oxygen containing ambient. The oxidation may be conducted during the thermal curing, tempering and/or shaping steps by conducting one or more of these annealing steps in air or in a pure oxygen ambient. The oxygen diffuses through the capping layer 132 into the transparent conductor bridge layer 130 to oxidize tire metallic indium and tin containing layer to improve its visible light transmissivity. The top portion of the metallic layer will be oxidized more than the bottom portion of the metallic layer to form the transparent conductor bridge layer 130 with tire graded oxygen concentration. The graded composition improves the transparent conductor bridge layer 130 stress differential during the curing and/or tempering processes.

[0036] The capping layer 132 may have has a thickness of 20 to 40 nm, such as 25 to 30 nm. The capping layers 132 may comprise tin antimony oxide, tin oxide or tantalum doped silicon nitride (Ta:SiN). In one embodiment, the first capping layer 132 compri ses the tin antimony oxide containing 30 to 50, such as 40 to 45 atomic percent tin, 1 to 5, such as 2 to 4 atomic percent antimony and 45 to 69, such as 58 to 65 atomic percent oxygen. The Sn:Sb ratio maximizes the transparent conductor (102a or 102b) to electrode (104 or 108) and electrolyte 106 electrical conductivity. The capping layer 132 prevents the transparent conductor bridge layer 130 from being overoxidized during the tempering step, which prevents tire transparent conductor bridge layer 130 from losing its structural stability.

[0037] The capping layer 132 may be formed by reactive sputtering from a tin antimony alloy target (e.g., 98:2 Sn:Sb ratio target) in an oxygen containing ambient. This Layer may be deposited slightly metallic for handling and chemical durability in the as deposited state The capping layer 132 may be oxidized during the curing process if the curing process is conducted in an oxidizing ambient. The capping layer 132 may be in compressive stress for electrode (104 or 108) integration.

[0038] if the capping layer 132 comprises tin antimony oxide, then it may have a predominant (211) plane orientation and a predominant [211] crystalline direction in the major surfaces. If the capping layer 132 comprise tin oxide, then it may have a predominant ( 110) plane orientation and a predominant [110] crystalline direction in the major surfaces. The capping layer 132 may have a refractive index of about 1.95 to 2.25, such as 2.05 to 2.15.

[0039] In one embodiment, the first layer stack 116 further comprises the insulating layer stack 118 located between the transparent substrate (110a or 110b) and the silver layer 126 of the transparent conductor (102a or 102b). The insulating layer stack 118 includes an electrically insulating index matching layer 122 located between the silver layer 126 and the transparent substrate (110a or 110b), an electrically insulating diffusion barrier and optical interface layer 120 located between the transparent substrate (110a or 110b) and the index matching layer 122, and an electrically insulating seed layer 124 located between the index matching layer 122 and toe silver layer 126.

[0040] In one embodiment, the transparent substrate (110a or 110b) comprises a glass substrate which contains sodium and the diffusion barrier and optical interface layer 120 comprises a material which blocks diffusion of sodium from the transparent substrate into toe index matching layer 122. For example, the diffusion barrier and optical interface layer 120 may comprise a silicon nitride, silicon oxynitride or silicon aluminum nitride layer having a thickness of 12 to 18 nm, such as 15 to 17 nm.

[0041] The diffusion barrier and optical interface layer 120 may have a density of at least 2.5 g/cm³, such as 3 to 3.5 g/cm³ to minimize sodium diffusion from the glass into the overlying layers during the subsequent annealing steps. The diffusion barrier and optical interface layer 120 may have a refractive index of 2 to 2.3 such as 2.1 to 2.25.

[0042] In one embodiment, tire diffusion barrier and optical interface layer 120 comprises the silicon aluminum nitride or silicon nitride comprising 40 to 50, such as 45 to 48 atomic percent silicon, 0 to 6, such as 4 to 5 atomic percent aluminum, and 44 to 58, such as 51 to 55 atomic percent nitrogen. In one embodiment, the diffusion barrier and optical interface layer 120 has a graded nitrogen composition as a function of thickness. The graded composition may he formed by reactive sputtering using plural (i.e., separate Si, Ai and/or SiAl alloy (e.g., 88:12 ratio Si:Al alloy) sputtering targets, and providing a higher nitrogen flow (e.g., at ieast 10 seem higher) to the downstream target than to the upstream target while the transparent substrate (110a or 110b) moves past the sputtering targets in a direction from the upstream target to the downstream target. The diffusion barrier and optical interface layer 120 is more metallic at its bottom surface contacting the glass transparent substrate (110a or 110b) than at its top surface which contacts the index matching layer 122 to prevent or reduce alkal i ion migration from the glass toward the silver layer 126 during the curing and/or tempering annealing steps.

[0043] In another embodiment, tire diffusion barrier and optical interface layer 120 comprises the silicon oxynitride which has graded oxygen composition as a function of thickness. The silicon oxynitride diffusion barrier and optical interface layer 120 is more oxidic at its top surface than its bottom surface to oxidize the metal (e.g., Ti or Nb) of the overlying index matching layer 122 during the thermal curing process.

[0044] The index matching layer 122 may comprise a titanium oxide or a niobium oxide layer having a refractive index that is higher than a refractive index of the first diffusion barrier and optical interface layer 120 for refractive index matching to increase the visible light transmission of the article 150. The index matching layer 122 may have a refractive index of 2.3 to 2.5 such as 2.34 to 2.49. In one embodiment, the index matching layer 122 comprises the titanium oxide having a thickness of 14 to 18 nm, such as 16 to 17 nm.

[0045] The titanium oxide may have an anatase crystal structure to avoid a phase change during subsequent thermal curing and tempering steps. In one embodiment, the index matching layer 122 comprises titanium oxide containing 30 to 45, such as 35 to 40 atomic percent titanium, and 55 to 70, such as 62 to 67 atomic percent oxygen. Preferably, the index matching layer 122 has a low surface roughness (e.g., Ra of 12-14 nrn and root mean square (RMS) of 16-17 nm) in order to deposit smooth seed layer and silver layer thereon.

[0046] The seed layer 124 may comprise a zinc aluminum oxide layer. The seed layer 124 may have a predominant [002] crystalline direction (e.g., a predominant (002) crystalline plane) in a top surface contacting the silver layer 126. This causes the silver layer 126 grown on the seed layer 124 to have a predominant [111] crystalline direction in a bottom surface contacting the seed layer 124. Specifically, the silver layer 126 grown on [002] zinc aluminum oxide may grow with a (111) out of plane orientation. Preferably, the seed layer 124 has a low surface roughness (e.g., Ra of 0.6 to 0.9 nm and RMS of 0.7 to 1.2 nm) and an average grain size of 9 to 15 nm to grow a low surface roughness and low sheet resistance silver layer 126 thereon.

[0047] In one embodiment, the seed layer 12.4 may have a thickness of 8 to 10 nm, such as about 9 nm. The seed layer 124 zinc aluminum oxide may comprise 45 to 60, such as 52 to 57 atomic percent zinc, 2 to 6, such as 4 to 5 atomic percent aluminum, and 34 to 53, such as 46 to 50 atomic percent oxygen. The seed layer 124 may have a refractive index of 1.8 to 2 such as 1.86 to 1.9.

[0048] In one embodiment, the seed layer 124 has a graded oxygen composition as a function of thickness. The graded composition may he formed by reactive sputtering using plural (i.e., separate Zn, A1 and/or ZnAl alloy (e.g., 98:2 ratio Zn:Al alloy) sputtering targets, and providing a higher oxygen flow (e.g., at least 10 seem higher) to the upstream target than to the downstream target while the transparent substrate (110a or 110b) moves past the sputtering targets in a direction from the upstream target to the downstream target. The seed layer 124 is more metallic at its top surface contacting the silver layer 126 than at its bottom surface which contacts the index matching layer 122 to improve the stiver layer 126 growth on the top surface of the seed layer 124 and to improve adhesion and stress control at the interface with the index matching layer 122.

[0049] Optionally, the seed layer 124 may include an additional tin oxide or zinc tin oxide stress balancing sublayer between the zinc aluminum oxide sublayer and the index matching layer 122. The stress balancing sublayer may have a thickness of 5 to 6 nrn to avoid or reduce stress gradients at the interface between the seed layer 124 and the index matching layer 122. [0050] Tables 1-13 below provide exemplary combinations of materials, thickness, thickness range and refractive index for the layers of exemplary layer stacks 116.

Table 1

Table 5

[0051] FIG. 3 illustrates an EC device 100 containing two articles 150 (e.g., 150b and 150b) separated by an electrolyte 106. The two articles 150a and 150b may be fabricated separately and the electrolyte 106 is then deposited between the two articles 150a and 150b.

[0052] The EC device 100 contains a first transparent substrate 110a, a second transparent substrate 110b, a working electrode 104 located between the first and the second transparent substrates, a counter electrode 108 located between the first and the second transparent substrates, the electrolyte 106 located between the working electrode 104 and the counter electrode 108, a first layer stack 116a located between the first transparent substrate 110a and the working electrode 104, and a second layer stack 116b located between the second transparent substrate 110b and the counter electrode 108. One of the layer stacks (116a or 116b), such as the first layer stack 116a comprises a first transparent conductor 102a comprising an optically transparent first silver layer 126a, and at least one electrically conductive, optically transparent first oxide layer (128a, 130a and/or 132a) located between the optically transparent silver layer 126a and the working electrode 104.

[0053] In one embodiment, the at least one electrically conductive, optically transparent first oxide layer comprises a first transparent conductor bridge layer 130a, a first thermal and mechanical protection layer 12,8a located between the first silver layer 126a and the first transparent conductor bridge layer 130a, and a first capping layer 132a located between the working electrode 104 and the first transparent conductor bridge layer 130a.

[0054] In one embodiment, the first layer stack 116a may also include a first insulating layer stack 118a including a first electrically insulating index matching layer 122a located between the first silver layer 126a and the first transparent substrate 110a, a first electrically insulating diffusion barrier and optical interface layer 120a located between the first transparent substrate 110a and the first index matching layer 122a, and a first electrically insulating seed layer 124a located between the first index matching layer 122a and the first silver layer 126a. [0055] In one embodiment, the second layer stack 116b comprises an optically transparent second silver layer 126b, a second transparent conductor bridge layer 130b located between the second silver layer 126b and the counter electrode 108, a second thermal and mechanical protection layer 128b located between the second silver layer I26b and the second transparent conductor bridge layer 130b, a second capping layer 132b located between the counter electrode 108 and the second transparent conductor bridge layer 130b, a second index matching layer 122b located between the second silver layer 126b and the second transparent substrate 110b, a second diffusion barrier and optical interface layer 120b located between the second transparent substrate 110b and the second index matching layer 122b, and a second seed layer 124b located between the second index matching layer 122b and the second silver layer 126b.

[0056] As shown in FIG. 3, external electrical contacts 160a and 160b are made to the respective first silver layer 126a and the second silver layer 126b. The external electrical contacts electrically connect the EC device 100 to an external power source and/or to a controller which switches tire EC device from the bright state to the dark state and vice-versa.

[0057] The embodiments of the present disclosure provide a silver based transparent conductor that also includes a structural indium tin oxide layer and an electrically conductive tin oxide or antimony tin oxide capping layer which contacts one of the electrodes and/or the electrolyte (if the electrode comprises a porous nanoparticle film). The transparent conductor can withstand long duration high temperature post processing annealing (e.g., curing and/or tempering) steps. The low resistivity silver layer reduces the EC device switching time by improving the transparent conductor conductivity. The silver layer also improves the solar heat gain coefficient of the EC device. The EC device may comprise a dynamic tinting device with a variable solar heat gain coefficient. The silver layer and indium tin oxide layers have thickness and refractive index ranges which increase visible light transmission and low b* transmission. The insulating diffusion barrier layer reduces or eliminates alkali ion contamination of the electrodes during the post processing annealing steps. The transparent conductor is post temperable and bendable, and can be coated on the glass substrate prior to the thermal tempering and/or bending step(s).

[1)058] The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may he acquired from practice of tire invention. The description was chosen in order to explain the principles of the invention and its practical application. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents.

Claims

1. An eleetrochromie device (EC device), comprising: a first transparent substrate; a second transparent substrate; a working electrode located between the first and the second transparent substrates; a counter electrode located between the first and the second transparent substrates; an electrolyte located between the working electrode and the counter electrode; a first layer stack located between the first transparent substrate and the working electrode; and a second layer stack located between the second transparent substrate and the counter electrode; wherein the first layer stack comprises a first transparent conductor comprising: an optically transparent first silver layer; and at least one electrically conductive, optically transparent first oxide layer located between the optically transparent silver layer and the working electrode.

2. The EC device of claim 1 , wherein the at least one electrically conducti ve, optically transparent first oxide layer comprises: a first transparent conductor bridge layer; a first thermal and mechanical protection layer located between the first silver layer and the first transparent conductor bridge layer; and a first capping layer located between the working electrode and the first transparent conductor bridge layer.

3. The EC device of claim 2, wherein: the first silver layer has a thickness of 5 to 11 nm; the first transparent conductor bridge layer has a thickness of 80 to 120 nm and comprises indium tin oxide or a hilayer of tin oxide and indium tin oxide; the first thermal and mechanical protection layer has a thickness of 1 to 4 nm and comprises nickel chromium oxide or titanium oxide; and the first capping layer has a thickness of 20 to 40 nm and comprises tin antimony oxide, tin oxide or Ta:SiN.

4. The EC device of claim 3, wherein: the first transparent conductor bridge layer comprises the indium tin oxide; the first thermal and mechanical protection layer comprises the nickel chromium oxide; and the first capping layer comprises the tin antimony oxide.

5. The EC device of claim 4, wherein: the first transparent conductor bridge layer comprises the indium tin oxide containing 35 to 50 atomic percent indium, 5 to 15 atomic percent tin, and 35 to 60 atomic percent oxygen; the first thermal and mechanical protection layer comprises tire nickel chromium oxide containing 20 to 40 atomic percent nickel, 5 to 15 atomic percent chromium, and 45 to 75 atomic percent oxygen; and the first capping layer comprises the tin antimony oxide containing 30 to 50 atomic percent tin, 1 to 5 atomic percent antimony and 45 to 69 atomic percent oxygen.

6. The EC device of claim 5, wherein: the first thermal and mechanical protection layer comprises the nickel chromium oxide having a graded composition as a function of thickness comprising a lower oxygen concentration at a surface contacting the first silver layer than at a surface contacting the first transparent conductor bridge layer; and the first transparent conductor bridge layer comprises the indium tin oxide having a graded composition as a function of thickness comprising a lower oxygen concentration at a surface contacting the first thermal and mechanical protection layer than at a surface contacting the first capping layer.

7. The EC device of claim 1 , wherein the first layer stack further comprises a first insulating layer stack located between the first transparent substrate and the first silver layer.

8. The EC device of claim 7, wherein the first insulating layer stack comprises: a first index matching layer; a first diffusion barrier and optical interface layer located between the first transparent substrate and the first index matching Layer; and a first seed layer located between the first index matching layer and the first silver layer.

9. The EC device of claim 8, wherein: the first transparent substrate comprises a first glass substrate which contains sodium; the first index matching layer comprises a titanium oxide or a niobium oxide layer having a refractive index that is higher than a refractive index of the first diffusion barrier and optical interface layer; the first diffusion barrier and optical interface layer comprises silicon nitride, silicon oxynitride or silicon aluminum nitride layer which blocks diffusion of sodium from the first transparent substrate into the first index matching layer; the first seed layer comprises a zinc aluminum oxide layer having a predominant [002] crystalline direction in a surface contacting the first silver layer; and the first silver layer has a predominant [i ll] crystalline direction in a surface contacting the first seed layer.

10. The EC device of claim 9, wherein: the first index matching layer comprises the titanium oxide layer having an anatase crystal structure, a thickness of 14 to 18 ran and comprising 30 to 45 atomic percent titanium and 55 to 70 atomic percent oxygen; the first diffusion barrier and optical interface layer comprises the silicon aluminum nitride layer having a graded composition as a function of thickness, a thickness of 12 to 18 nm and comprising 40 to 50 atomic percent silicon, 2 to 6 atomic percent aluminum, and 44 to 58 atomic percent nitrogen; and the first seed layer comprises the zinc aluminum oxide layer having a graded composition as a function of thickness, a thickness of 8 to 10 nm and comprising 45 to 60 atomic percent zinc, 2 to 6 atomic percent aluminum, and 34 to 53 atomic percent oxygen.

11. The EC device of claim 1 , wherein the first transparent conductor has a sheet resistance between 3 Ohm/sq and 5 Ohm/sq.

12. The EC device of claim 1 , wherein the EC device is incorporated into a window or sunroof of a vehicle.

13. The EC device of claim 1, wherein the second layer stack comprises: an optically transparent second silver layer; a second transparent conductor bridge layer located between the second silver layer and the counter electrode; a second thermal and mechanical protection layer located between the second silver layer and the second transparent conductor bridge layer; a second capping layer located between the counter electrode and the second transparent conductor bridge layer; a second index matching layer located between the second silver layer and the second transparent substrate; a second diffusion barrier and optical interface layer located between the second transparent substrate and the second index matching layer; and a second seed layer located between the second index matching layer and the second silver layer.

14. An article, comprising: a transparent substrate; an electrode; an optically transparent silver layer located between the transparent substrate and the electrode; an electrically conductive transparent conductor bridge layer located between the silver layer and the electrode; an electrically conductive thermal and mechanical protection layer located between the silver layer and tire transparent conductor bridge layer; and an electrically conductive capping layer located between the electrode and the transparent conductor bridge layer.

15. The article of claim 14, further comprising: an electrically insulating index matching layer located between the silver layer and the transparent substrate; an electrically insulating diffusion barrier and optical interface layer located between the transparent substrate and the index matching layer; and an electrically insulating seed layer located between the index matching layer and the silver layer.

16. A method, comprising: forming an electrically conductive and optically transparent silver layer over a transparent substrate; forming an electrically conductive thermal and mechanical protection layer over the silver layer; forming an electrically conductive transparent conductor bridge layer over the thermal and mechanical protection layer; forming an electrically conductive capping layer over the transparent conductor bridge layer; and forming a first electrode over the capping layer.

17. The method of claim 16, further comprising, prior to forming the silver layer, forming an electrically insulating diffusion barrier and optical interface layer over the transparent substrate; forming an electrically insulating index matching layer over the diffusion barrier and optical interface layer; and forming an electrically insulating seed layer over the index matching layer, wherein the silver layer is formed on the seed layer by sputtering in an argon and hydrogen plasma.

18. The method of claim 17, further comprising providing a second electrode and providing an electrolyte between the first electrode and the second electrode to form an eiectrochromic device in which one of the first and the second electrodes comprises a working electrode and another one of the first and the second electrodes comprises a counter electrode.

19. The method of claim 17, further comprising: curing the electrically conductive and the electrically insulating layers formed over the transparent substrate at a temperature above 350 degrees Celsius, such that the thermal and mechanical protection layer prevents or reduces flow of the silver layer during the curing; and tempering the transparent substrate at a temperature above 500 degrees Celsius after forming the first electrode, wherein the transparent substrate comprises a glass substrate.

20. The method of claim 19, wherein the layers are formed by sequentially sputtering the electrically insulating layers and the electrically conductive layers while the transparent substrate continuously moves through different sputtering chambers.