Method for manufacturing a curved electrochromic device

Abstract

A method is disclosed for producing curved electrochromic devices by depositing solution-based materials directly onto curved surfaces. The curved electrochromic devices are produced by spray-coating a first curved conductive substrate with a solution of one or more (cathodic) inorganic or organometallic precursors, and then exposing the coated substrate to near-infrared, ultraviolet or ozone to convert the one or more (cathodic) inorganic or organometallic precursors into a (cathodic) electrochromic layer. A second complementary conductive curved substrate is coated with a second (anodic) electrochromic layer. An electrolyte layer is incorporated between the first and second electrochromic layers, and the substrates are sealed together to form a curved electrochromic device. The method is particularly useful for curved electrochromic devices using bent or heat-strengthened glass.

Description

[Technical field]

[0001] The present invention relates to the field of electrochromic devices, and in particular to methods for their manufacture. [Background technology]

[0002] "Smart window" or "smart glass" refers to a device that can change its color or light transmission or reflection by electronic switching. When the bias is electrical (e.g., a voltage is applied), the device is called an electrochromic (EC) device. These devices can be used in variable transmission windows used in architecture and transportation (cars, airplanes, passenger trains, ferries, etc.), displays, and automotive mirrors to control reflectance. Adjusting the transmission window also changes the solar energy transmitted through the window.

[0003] Although windows are increasingly in demand in new construction projects, they are widely considered to be one of the least efficient components of a building envelope. Heating, ventilation, and air conditioning (HVAC) and lighting in buildings account for over 30% of primary energy consumption worldwide, and up to half of this energy can be lost through windows. This energy loss leads to increased greenhouse gas (GHG) emissions and energy costs for building owners. The use of smart windows in residential and commercial buildings can help improve the energy efficiency of buildings. Electrochromic windows can reduce a building's heating, cooling, and lighting needs by 20%. Additionally, these windows can provide shading and reduce glare, ultimately leading to increased worker productivity.

[0004] Electrochromic glass (also known as electrochromic glazing) in the automotive industry is currently used in small area rearview and side mirrors. The automotive industry is interested in expanding this product to sunroofs and side windows to improve passenger experience (especially as ride sharing brings more passengers into the backseat). Air conditioning systems cool, heat, and ventilate the interior of the vehicle. These air conditioning systems are electrically powered and their use can reduce the range of electric vehicles (EVs) by 30-40%, depending on the size of the air conditioning system, the climate, and the driving cycle. Smart glass windows can help manage the interior climate of vehicles, thus reducing the use of air conditioning and increasing the range of EVs. Their use in transportation can therefore enable more energy efficient vehicles.

[0005] For vehicle glazing (such as sunroofs and moonroofs), curved surfaces are generally preferred or required to maintain aerodynamic and aesthetic properties. Other examples where curved electrochromic devices are utilized include architectural windows, ski goggles, eyeglasses, rearview mirrors, car windows, skylights, etc. In some cases, these applications require double curved (compound) or complex curved surfaces.

[0006] For example, US Patent No. 5,953,150 discloses a method for producing curved electrochromic devices for lenses. Here, the electrochromic layer is deposited on a separate ITO-coated plastic substrate, and an ion-conducting polymer is used to laminate the two substrates. The patent uses a vacuum deposition method to apply the functional coating. Sputtering, a vacuum deposition process, is a commonly used industrial process for depositing thin films, layers, and coatings. However, it is difficult to coat curved surfaces uniformly with sputtering. Furthermore, areas of the curved substrate are closer to the sputtering target and therefore experience a higher thermal load. For some substrate types, this can be problematic (e.g., thermoplastic substrates can deform). Furthermore, the distribution of the sputtered material can change over time as the target erodes, it is an expensive process, and the method is known to produce pinholes.

[0007] To overcome the challenges of sputtering on curved surfaces, an alternative manufacturing method for producing curved electrochromic devices has been developed in which a flat substrate is coated after the electrochromic stack is deposited and then molded to the curved surface.

[0008] U.S. Pat. No. 7,808,692 discloses a method for making a permanently curved electrochromic device, which is formed by first coating a thermoplastic substrate, which can then be curved by thermoforming the substrate into a permanent curve.

[0009] U.S. Pat. No. 1,066,3831 discloses a method of producing a curved electrochromic film by first forming a flat electrochromic film, then placing a UV curable layer between first and second electrochromic materials, then bending the film using a forming device and curing the UV curable layer using a UV light source while the film is in an arched position.

[0010] However, problems can arise when bending flat electrochromic films or layers: depending on the curvature required, the bending stresses may be too great, causing delamination, cracking, or other separation within the electrochromic stack.

[0011] Other coating methods such as curtain coating and slot die coating have their own challenges when it comes to coating on curved surfaces. In some cases, the coating setup must be redone for each substrate with a different curvature or size. Additionally, these wet application methods can result in uneven layers due to gravity, surface tension, and capillary forces that cause the coating to pool or streak on the curved substrate.

[0012] US Patent No. 10,871,695 discloses an electrochromic multilayer device that includes a conductive layer that changes as a function of position. It is stated therein that electrochromic architectural windows typically employ substrates with flat surfaces, but it is envisioned that the multilayer device may have single or double curved surfaces. However, no method is disclosed for producing curved devices.

[0013] US Patent Publication No. 2019 / 0196289 discloses a curved electrochromic device in which an electrochromic compound can be applied to an electrolyte membrane or a transparent conductive oxide layer on a dome (curved surface). The application states that preferably, the electrochromic compound is applied to the electrolyte membrane before the membrane is fully cured. The disclosure relates to organic electrochromic compounds such as poly(3,4-ethylenedioxythiophene) (PEDOT), which are known to have durability issues and tend to be size limited compared to electrochromic metal oxides.

[0014] The bending process of substrates, especially glass, can be a significant source of material failure or the introduction of defects, therefore, when manufacturing curved electrochromic devices, it is advantageous to complete the bending of the substrate prior to the application of the electrochromic layers, which can be expensive.

[0015] Therefore, there is a need for a convenient method for manufacturing curved, double curved, or complex curved electrochromic devices that reliably produces a uniform thickness of electrochromic coating applied to an already curved substrate. Summary of the Invention [Problem to be solved by the invention]

[0016] It is an object of the present invention to provide a method for manufacturing a curved electrochromic device. In one aspect of the present invention, a method for manufacturing a curved electrochromic device is provided, comprising: providing a first curved substrate having a first transparent conductive coating on one surface; coating the first conductive coating with a cathodic electrochromic metal oxide layer, where the cathodic electrochromic metal oxide layer material is formed by a process comprising the steps of: i) spray coating the first transparent conductive coating on the first curved substrate with a solution containing one or more inorganic or organometallic cathodic precursors to form a precursor layer; and ii) exposing the precursor layer to near infrared, ultraviolet, or ozone to convert the one or more inorganic precursors to the first cathodic electrochromic metal oxide layer to form a first coated curved substrate; providing a second curved substrate having a second transparent conductive coating on one surface, where the second curved substrate has a curvature complementary to that of the first curved substrate. coating the second conductive coating with an anodic electrochromic metal oxide layer, where the anodic electrochromic metal oxide layer material is formed by a process including the steps of: iii) spray coating the second transparent conductive coating on the second curved substrate with a solution including one or more inorganic or organometallic anodic precursors to form a precursor layer; and iv) exposing the precursor layer to near infrared, ultraviolet or ozone radiation to convert the precursor layer to an anodic electrochromic metal oxide layer and form a second coated curved substrate; incorporating an electrolyte layer between the cathodic electrochromic metal oxide layer on the first coated curved substrate and the anodic electrochromic metal oxide layer on the second coated curved substrate; and sealing the device to form a curved electrochromic device, where the sealing step may occur before or after the incorporation of the electrolyte.

[0017] In accordance with another aspect of the present invention, there is provided a curved electrochromic device manufactured using the method of the present invention. [Brief description of the drawings]

[0018] The particular arrangement shown in the figures should not be considered limiting, and it should be understood that the illustrated elements, including shape, size and scale, are not necessarily drawn to scale relative to each other.

[0019] Further features and advantages of the present disclosure will become apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

[0020] [Figure 1] FIG. 1 is a schematic diagram of a curved electrochromic device and its components that can be fabricated using the methods of the present invention, in one embodiment. [Diagram 2] FIG. 2 is a graph showing the change in CIE Y transmittance in the bleached and colored states over 30 cycles for a curved electrochromic device made in accordance with one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Detailed explanation The method of the present invention provides an improved method for manufacturing curved electrochromic devices. Additionally, the present invention provides a method for uniformly and efficiently coating rigid curved substrates for electrochromic devices.

[0022] The present disclosure generally relates to methods for making curved electrochromic devices that are prepared by applying an electrochromic layer directly to a rigid, curved substrate surface.

[0023] A method for producing a curved rigid electrochromic device includes providing a first curved substrate having a first transparent conductive coating on one surface; and a second curved substrate having a curvature complementary to the first curved substrate and having a second transparent conductive coating on one surface. A first (cathodic) electrochromic metal oxide layer is applied to the conductive coating on the first substrate by a process including: i) coating the curved substrate coated with the first transparent conductive coating with a solution of one or more inorganic or organometallic precursors to form a precursor layer; and ii) exposing the precursor layer to near infrared, ultraviolet, or ozone to convert the one or more inorganic or organometallic precursors to the (cathodic) metal oxide layer. A second (anodic) electrochromic layer is applied to the second curved substrate by the same process as described for the first curved substrate, but using a solution of inorganic or organometallic precursors to form the anodic metal oxide layer. Once the first and second curved substrates are formed into their respective electrochromic metal oxide layers, an electrolyte layer is incorporated between the first and second electrochromic metal oxide layers. The resulting layered structure is then sealed to form a curved electrochromic device.

[0024] The method of the present invention provides a scalable solution-based process for fabricating curved electrochromic devices.

[0025] Unless otherwise required by context, throughout this specification and claims, words such as "comprise", "comprising" and the like are to be construed in an open and inclusive sense. Words such as "a", "an", and the like are to be deemed to mean "at least one" and are not limited to one.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0027] As used herein, the term "singly curved" refers to a curved surface having a radius in one plane.

[0028] As used herein, the term "doubly curved" refers to a surface that has radii in two planes (the surface curves in two directions simultaneously). An example of such a surface is a sphere. The term "compound curved" is another term that is used interchangeably with doubly curved herein.

[0029] As used herein, the term "complexly curved" refers to a curved surface that has two or more radii or that has multiple distinct curvatures across its surface.

[0030] As used herein, the term "anodic electrochromic layer" refers to a layer containing a solid inorganic electrochromic material that transitions to a colored state when ions are extracted from it. In this application, it is disposed parallel to and between a conductive layer and an ion-conducting layer in an electrochromic device.

[0031] As used herein, the term "cathodic electrochromic layer" refers to a layer containing a solid inorganic electrochromic material that transitions to a colored state upon ion insertion. In this application, it is disposed parallel to and between an electrically conductive layer and an ion-conducting layer in an electrochromic device.

[0032] As used herein, the term "cycled" refers to applying a bias voltage across the device by an external power source such as a battery, potentiostat, etc., and then reversing the polarity after a predetermined time. The reverse polarity may be a voltage different from the original bias voltage. The bias polarity is then reversed again to complete the "cycle."

[0033] As used herein, the term "electrochromic device" refers to an electrochemical device comprising a substrate, an anode electrode, a cathode electrode, an ionically conductive layer, and charge-balancing ions, which can be transitioned from a colored state (i.e., low light transmission through the window) to a transparent state (i.e., high light transmission through the window) and / or from a transparent state to a colored state through the use of an applied electrical bias. The "transparent" state may also be referred to as the "bleached" state.

[0034] As used herein, the term "ionically conductive" refers to the ability of a material to shuttle ions between different sites. As an example, an ionically conductive material herein is capable of shuttling lithium ions between an anode and a cathode upon the introduction of an external electrical bias.

[0035] As used herein, the term "ligand" refers to any chemical group coordinated, chemically or ionically bonded to a metal or metalloid. Representative examples of ligands include, but are not limited to, chloride, bromide, nitrate, 2-ethylhexanoate, ethoxide, butoxide, isopropoxide, acetate, oxalate, acetylacetonate, and the like.

[0036] As used herein, the term "photodeposition" refers to a process in which a chemical precursor that is solution deposited on a substrate or electrode is exposed to UV or NIR electromagnetic radiation, or a combination thereof (in the presence or absence of ozone), resulting in photochemical conversion to an inorganic oxide layer.

[0037] As used herein, the term "substrate" refers to a mechanical support material onto which additional functional layers are assembled.

[0038] FIG. 1 shows a schematic of a multi-layer structure of an electrochromic device that can be made using the method of the present invention. In this case, FIG. 1 represents the device connected to an external power source. The electrochromic device includes a first curved substrate (1), a first transparent conductive layer (2), an anodic electrochromic layer or ion storage layer (3), an ion-conducting electrolyte layer (4), a cathodic electrochromic layer (5), a second transparent conductive layer (6), and a second curved substrate (7). The substrates (1, 7) provide the base structure and protection of the internal layers of active device materials. The (transparent) conductive layers (2, 6) provide a means of conducting charge from an external power source to the electrochromic layers (3, 5) and / or a means of controlling electronics and software. The conductive electrolyte layer (4) provides a means of transporting ions between the anode (3) and cathode (5) electrochromic layers. It is within the scope of the present invention if the order of layers is reversed relative to the substrate. That is, the order may be first substrate, first transparent conductive layer, cathodic electrochromic layer, electrolyte layer, anodic electrochromic layer or ion storage layer, second transparent conductive layer, and second substrate. It may also be within the scope of the present invention to optionally apply additional protective and functional layers. The layer thicknesses, layer shapes, sizes, and scales of the device are not drawn to scale or to actual proportions, but are depicted for clarity.

[0039] When a voltage is applied between the electrodes, an electric field is generated within the insulating electrochromic material, which can cause the migration of ions into or out of the electrochromic material, resulting in a color change in the electrochromic material (e.g., from a colorless to a colored state when switched from one electrochromic state to another). By reversing the applied bias, the electrochromic material can, for example, revert from a colored state back to a colorless (or bleached) state. Alternatively, an electrochromic material can be initially colored, switch to a colorless state by applying a voltage, and then revert to a colored state by reversing the applied bias (e.g., tungsten oxide-based materials become colored by ion insertion, and nickel oxide-based materials become colored by ion extraction).

[0040] When manufacturing electrochromic devices, there are many potential failure points that can be encountered during the manufacturing process. Ideally, if a defect is detected in the material, the production of the device is stopped as early as possible in the manufacturing process. Considering that the process of bending the substrate can be a significant source of failure or introduction of material defects, it is advantageous to perform the bending operation before applying expensive functional layers to the substrate material.

[0041] The curved transparent substrate (1, 7) includes, but is not limited to, glass, plastic, and / or polymer. The transparent substrate should have optical, electrical, thermal, and mechanical properties suitable for the desired application. In one embodiment, the curved transparent substrate is selected from the group consisting of glass, polyethylene terephthalate (PET), polycarbonate, polyethylene naphthalate (PEN), polyvinyl butyral (PVB), polymethyl methacrylate (PMMA), acrylic, transparent acrylonitrile butadiene styrene (ABS), methyl methacrylate acrylonitrile butadiene styrene (MABS), polyvinyl chloride (PVC), amorphous copolyester (PETG), general purpose polystyrene, styrene acrylonitrile resin (SAN), styrene methyl methacrylate (SMMA), fluorinated ethylene propylene (FEP), transparent polypropylene, ionomer resin, polyethylene (PE), cyclic olefin copolymer, thermoplastic polyurethane (TPU), and liquid silicone rubber (LSR). In a preferred embodiment, the curved transparent substrate is selected from the group consisting of glass, polyethylene terephthalate (PET), polycarbonate, polyethylene naphthalate (PEN), polyvinyl butyral (PVB), polymethyl methacrylate (PMMA), acrylic, and polyvinyl chloride (PVC).

[0042] If the substrate is made of glass, it may further include a sodium barrier layer. It is within the scope of the present invention that the first transparent substrate and the second transparent substrate are the same or different materials. In one embodiment, both curved transparent substrates are glass. In another embodiment, both curved transparent substrates are tempered or heat-strengthened glass. In another embodiment, both curved transparent substrates are polycarbonate. In another embodiment, the curved transparent substrates are independently glass, polycarbonate, or polyethylene terephthalate.

[0043] An advantage of the method of the present invention is that it allows for the use of curved tempered glass substrates and heat strengthened substrates.

[0044] Tempered glass is ordinary glass that has been strengthened by controlled thermal or chemical treatment. The tempering process stresses the glass so that when it breaks, it shatters into smaller pieces rather than larger, jagged pieces. Tempered glass is therefore used in a variety of applications due to its safety. However, exposure to high temperatures weakens the temper of tempered glass, eliminating its strength and safety benefits during use. Advantageously, the method described herein allows for the application of a coating of electrochromic material directly to (curved) tempered glass. Furthermore, the tempering process often results in glass with significant warping (deviations from flat) due to roller waves and edge kinks. The method of the present invention provides the ability to produce high quality electrochromic devices on conventional tempered glass with uneven or defective surfaces.

[0045] In one embodiment, the curved transparent substrate is single curved, resulting in a single curved electrochromic device. In another embodiment, the curved transparent substrate is double curved (or compound curved), resulting in a double curved (compound curved) electrochromic device. In yet another embodiment, the curved transparent substrate is compound curved, resulting in a compound curved electrochromic device.

[0046] In one embodiment, the radius of curvature of the curved transparent substrate is about 300 mm to about 4000 mm. In another embodiment, the radius of curvature of the curved transparent substrate is about 750 mm to about 3000 mm. In yet another embodiment, the radius of curvature of the curved transparent substrate is about 1000 mm to about 2000 mm.

[0047] In one embodiment, each of the curved transparent substrates is glass. In another embodiment, each of the curved transparent substrates is tempered glass or heat strengthened glass. In another embodiment, each of the curved transparent substrates is polycarbonate. In another embodiment, each of the curved transparent substrates is independently glass, polycarbonate, or polyethylene terephthalate.

[0048] The present invention also allows for electrochromic devices with a rigid curved substrate as the first curved substrate to be combined with a flexible substrate as the second curved substrate. Alternatively, the substrate configuration may be reversed, with the first curved substrate being the flexible substrate and the second curved substrate being the rigid curved substrate.

[0049] According to the method of the present invention, each curved substrate (1, 7) is provided with a transparent conductive layer (2, 6), respectively, and the transparent conductive coating (2, 6) is typically a coating comprising a transparent conductive oxide (TCO). The conductive coating should provide sufficient conductance for the electrochromic device and not significantly impede the transmission of light. The transparent conductive coating on each substrate may be the same material or different materials. In one embodiment, the transparent conductive coating comprises fluorine tin oxide (FTO); indium tin oxide (ITO); aluminum zinc oxide (AZO), silver mesh, silver nanowires, silver nanoparticles, carbon nanotubes, carbon black, graphene, conductive polymers, or a combination of two or more thereof. In a preferred embodiment, the transparent conductive coating comprises FTO or ITO.

[0050] The maximum use temperature for ITO coated glass is preferably below 350°C, whereas FTO coated glass can be used up to 600°C. Therefore, the high temperature processes of the prior art for manufacturing electrochromic substrates, such as sol-gel processes, cannot be used for ITO coated substrates. In contrast, the low temperature spray coating and photodeposition steps of the present method allow the process to be carried out on ITO or FTO coated substrates.

[0051] Electrochromic Layer Efficient electrochromic layers (3, 5) exhibit high color contrast between the colored and bleached states, fast conversion between the colored and bleached states, switching at low applied voltages, and excellent cyclability between states.

[0052] There are many types of electrochromic materials that can be used in electrochromic devices, including organic dyes and surface-bound electrochromic layers, including metal oxides. Most architectural electrochromic windows currently on the market employ metal oxides because they are more durable than their organic counterparts and generally switch more uniformly when used over larger window areas. In a preferred embodiment, the electrochromic device of the present invention employs a metal oxide-based electrochromic coating.

[0053] Creating active (electrochromic) metal oxide or mixed metal oxide layers is a critical step in the manufacture of oxide-based electrochromic cells. Historically, sputtering, a physical vapor deposition process in vacuum (including direct current magnetron, electron beam and radio frequency), has been the most widely used method for depositing thin films (layers) and coatings in the electrochromic industry. Although highly versatile, sputtering requires a vacuum chamber and high energy for operation and faces challenges with forming uniform coatings on curved surfaces.

[0054] Alternative techniques to sputtering, such as slot die coating and curtain coating, do not readily accommodate coating of curved surfaces, especially when the radius of curvature of the material being coated varies. Slot dies require that the surface being coated be flat, limiting the curvature and waviness to the thickness of the meniscus of the slot die. Curtain coating is not practical for curved surfaces because gravity causes the solution to flow down the slope of the curved surface, which can result in uneven coating. In contrast to these prior art methods of applying coatings to curved surfaces, the method of the present invention allows for the application of uniform coatings to rigid curved substrates of varying curvature.

[0055] According to a preferred embodiment of the present invention, the electrochromic coating is applied using a spray coater. In one embodiment of the present invention, the curved substrate is moved under a stationary spray coater nozzle from which a solution of one or more inorganic or organometallic precursors is ejected. In another embodiment, the substrate remains stationary and the spray coater nozzle moves over the curved substrate to coat the entire substrate. In yet another embodiment, both the substrate and the spray coater nozzle are moved relative to each other.

[0056] Using the method of the present invention, the resulting electrochromic coating can be adjusted to a desired thickness as required. In one embodiment, the thickness is adjusted by controlling the movement speed of the spray coater nozzle and / or the substrate. In one embodiment, the spray coater nozzle moves relative to the surface of the curved substrate at a speed of 20 to 50 feet per minute.

[0057] In one embodiment, a single pass provides good results by slowing down the speed of movement of the substrate or nozzle, while in another embodiment, the substrate area is exposed to the spray coating solution in multiple passes until the desired thickness is achieved.

[0058] According to the method of the present invention, the coating solution is a solution of one or more inorganic or organometallic precursors. The solution is prepared by dissolving a metal precursor or precursors in a compatible solvent and then applied to the substrate surface. Upon drying, a layer of the desired precursor or precursors is formed on the substrate. Examples of compatible solvents include, but are not limited to, water, methanol, ethanol, isopropanol, acetone, hexane, methyl isobutyl ketone, propylene glycol methyl ether acetate (PGMEA), ethyl acetate, acetonitrile, ethylene glycol, tetrahydrofuran (THF), toluene, and N-methylpyrrolidone. Any solvent capable of dissolving the precursor may be suitable for use in the present method.

[0059] In a typical electrochromic device, one of the curved transparent conductive substrates contains a cathodic electrochromic layer and the other of the curved transparent conductive substrates contains an anodic electrochromic layer.

[0060] Tungsten oxide (WOx) is a known cathodic electrochromic material that cycles between a light yellow (or transparent) fully oxidized state and a deep blue partially reduced state in electrochromic devices. The transparent material can be electrochemically reduced in the presence of lithium ions to form a colored reduced state (LiWOx) and reversibly reoxidized to a transparent state. Examples of other electrochromic cathodic materials suitable for use in the device of the present invention include, but are not limited to, molybdenum oxide (MoOx), titanium oxide (TiOx), tantalum oxide (TaOx) and niobium oxide (NbOx).

[0061] Nickel oxide (NiOx) is a known anodic electrochromic material that is complementary to tungsten oxide to produce a better colored dark state in an electrochromic cell. The deposition of NiOx layers is typically done by sputtering. Another example of an anodic electrochromic material suitable for use in the device of the present invention is iridium oxide. Materials such as cobalt oxide (CoOx), manganese oxide (MnOx), and iron oxide (FeOx) have also been shown to exhibit electrochromic behavior, but are not ideal because they do not completely bleach. Vanadium oxide (VOx) is also a known anodic electrochromic material.

[0062] In one embodiment, the electrochromic layer comprises a metal oxide selected from the group consisting of NiOx, WOx, MoOx, TiOx, TaOx, VOx, NbOx, CoOx, IrOx, MnOx, FeOx, LiNiOx, WNbOx, TiWOx, LiWOx, NiNbOx, NiNbLiOx, NiAlLiOx, or combinations thereof. In a preferred embodiment, the cathodic electrochromic layer is WOx, WNbOx, TiWOx, LiWOx, or combinations thereof. In a preferred embodiment, the anodic electrochromic layer comprises NiOx, LiNiOx, NiNbOx, NiNbLiOx, NiAlLiOx, VOx, or combinations thereof. In one embodiment, the electrochromic metal oxide layer consists primarily of tungsten oxide. In one embodiment, the electrochromic metal oxide layer consists primarily of nickel oxide.

[0063] In one embodiment, the electrochromic metal oxide layer is a doped metal oxide, where the dopant atoms are selected from niobium, aluminum, cerium, lithium, tantalum, molybdenum, cobalt, silicon, and titanium.

[0064] Precursors suitable for use in the various processes of the present invention include any inorganic or organometallic compound that can be converted to the corresponding oxide by exposure to photodeposition. Suitable precursors include, but are not limited to, inorganic chlorides, inorganic nitrates, inorganic acetates, organometallic 2-ethylhexanoates, organometallic butoxides, organometallic ethoxides, organometallic methoxides, organometallic isopropoxides, organometallic acetylacetonates, organometallic silanolates, organometallic oxalates, or mixtures thereof. Exemplary embodiments of precursors include tungsten(VI) chloride, tungsten(VI) isopropoxide, vanadium(III) chloride, tantalum(V) ethoxide, niobium(IV) 2-ethylhexanoate, niobium(V) ethoxide, nickel(II) acetate tetrahydrate, nickel(II) 2-ethylhexanoate, lithium methoxide, lithium ethoxide, lithium 2-ethylhexanoate, lithium trimethylsilanolate, and molybdenum(IV) 2-ethylhexanoate.

[0065] In one embodiment, the present invention provides a method for preparing a curved electrochromic device comprising, in part, spray coating a curved, rigid substrate with a precursor solution to form a precursor layer on the substrate, followed by subjecting the layer to photodeposition to convert the coated precursor layer on the substrate to a desired metal oxide or mixed metal oxide.

[0066] The photodeposition step may be carried out by exposing the precursor layer to one or more of near infrared radiation, ultraviolet radiation, and ozone.

[0067] Near infrared photodeposition uses infrared light to decompose precursors to produce the corresponding inorganic solid ionically conductive layers. U.S. Pat. No. 10,173,210 describes a near infrared (NIR) driven decomposition method for preparing metal oxides and mixed metal oxides, the entire disclosure of which is incorporated herein by reference in its entirety within the jurisdictions where such incorporation is permitted.

[0068] UV photodeposition is carried out at ambient or elevated temperatures and converts precursors into the corresponding inorganic solid ionically conductive layers by ultraviolet light, or a combination of ultraviolet light and ozone. U.S. Patent No. 9,803,287 describes UV photodeposition techniques for producing metal oxides and mixed metal oxides for making electrocatalysts, the entire disclosure of which is incorporated herein by reference in its entirety within the jurisdictions in which it is permitted.

[0069] U.S. Patent Application Publication No. 2020 / 165161 describes photodeposition techniques for producing metal oxides and mixed metal oxides for producing electrochromic layers and devices, the entire disclosure of which is incorporated by reference herein in its entirety within jurisdictions where such incorporation is permitted.

[0070] In one embodiment of the manufacture of electrochromic layers on substrates, a precursor solution is prepared as described above and coated onto a suitable surface, and the resulting thin precursor layer is subjected to a photodeposition process until decomposition is confirmed by monitoring the loss of ligands using analytical methods. In embodiments of the present invention in which the precursor contains organic ligands, the formation of the desired metal oxide can be monitored by infrared (IR) or Fourier transform infrared (FTIR) spectroscopy, since the loss of ligand from the precursor results in the disappearance of the ligand signal in the infrared spectrum. For precursors that cannot be traced by infrared spectroscopy, including but not limited to metal chloride salts, the conversion to metal oxide can be monitored using X-ray fluorescence (XRF) spectroscopy.

[0071] In some embodiments, the electrochromic precursor layer is comprised of multiple layers and undergoes photodeposition between each layer. In another embodiment, the electrochromic precursor layer is comprised of multiple layers and is subjected to a photodeposition process only after all layers of precursor are applied. In another embodiment, the electrochromic precursor layer is comprised of multiple layers and is subjected to a photodeposition process after every second, third, or fourth layer of precursor is applied. In another embodiment, the electrochromic precursor layer is comprised of multiple layers and is subjected to photodeposition after every fifth, sixth, or seventh layer of precursor is applied.

[0072] In one embodiment, the resulting electrochromic metal oxide layer may undergo an annealing step, for example, at about 30° C. to about 600° C. In a particular embodiment, the electrochromic metal oxide layer undergoes an annealing step in an oven in air at a temperature range of about 30° C. to about 600° C. for about 15 minutes to about 1 hour. In one embodiment, the layer undergoes an annealing step at about 50° C. for about 15 minutes to about 1 hour. In one embodiment, the layer undergoes an annealing step at about 100° C. for about 15 minutes to about 1 hour. In another embodiment, the layer undergoes an annealing step at about 200° C. for about 15 minutes to about 1 hour. In yet another embodiment, the layer undergoes an annealing step at about 300° C. for about 15 minutes to about 1 hour. In another embodiment, the layer undergoes an annealing step at about 350° C. for about 15 minutes to about 1 hour. In another embodiment, the layer undergoes an annealing step at about 400° C. for about 15 minutes to about 1 hour. In yet another embodiment, the layer undergoes an annealing step at about 450° C. for about 15 minutes to about 1 hour.

[0073] In one embodiment, the average thickness of the electrochromic layer is from about 10 nm to about 2000 nm. In another embodiment, the average thickness of the electrochromic layer is from about 100 nm to about 800 nm. In a preferred embodiment, the average thickness of the electrochromic layer is from about 200 nm to about 700 nm.

[0074] In certain embodiments, an additional layer is added to the electrochromic layer of either or both of the curved transparent substrates. In one embodiment, the additional layer is a barrier layer. In certain embodiments, the additional barrier layer comprises niobium oxide, lithium oxide, titanium oxide, tantalum oxide, cerium oxide, zirconium oxide, aluminum oxide, or mixtures thereof. In another embodiment, the barrier layer comprises niobium oxide, zirconium oxide, lithium oxide, or mixtures thereof.

[0075] In the electrochromic device of the present invention, the anodic and cathodic electrochromic layers are separated by an ionically conductive electrolyte layer (4). The role of the electrolyte layer (4) in the electrochromic cell is to allow ions and current to move between the anodic and cathodic materials. This layer can be liquid, gel or solid. In one embodiment, the electrolyte layer is an electrolyte solution comprising a lithium salt dissolved in propylene carbonate. In one embodiment, the electrolyte layer is a polymer gel comprising a resin; a lithium salt; a solvent component; an optional plasticizer component; and an optional crosslinker. In another embodiment, the electrolyte layer is a polymer gel comprising a difunctional oligomer; a monofunctional monomer; a lithium salt; a plasticizer; and a photoinitiator. In yet another embodiment, the electrolyte layer is a solid layer comprising at least one ionically conductive metal oxide material.

[0076] The electrolyte layer may be formulated with additives to enhance its performance or durability, including, but not limited to, fillers, UV stabilizers, heat stabilizers, adhesion improvers, antioxidants, radical scavengers, moisture scavengers, crosslinkers, UV absorbers, pigments, dyes, IR absorbers, IR blockers, surfactants, cheating agents, and impact modifiers, in addition to other additives known to those skilled in the art.

[0077] The electrolyte layer is encapsulated between the anodic and cathodic electrochromic layers and isolates the electrolyte interface from the outside atmosphere. In one embodiment, the sealing step uses a hot melt material that melts and seals as the electrolyte cures. In one embodiment, the sealing step uses double sided tape. In one embodiment, the sealing step uses a material that is applied following a curing process that initiates curing.

[0078] In one embodiment of the present invention, tungsten oxide is formed on a curved transparent conductive oxide coating by subjecting a tungsten precursor layer to photodeposition, and then incorporated into a curved electrochromic cell (a cell that can transition from opaque to transparent, or transparent to opaque to transparent, with the use of an applied electrical bias).

[0079] In another embodiment of the invention, nickel oxide is formed on a curved transparent conductive oxide coating by subjecting a nickel precursor layer to photodeposition or pyrolysis and then incorporated into a curved electrochromic cell (a cell that can transition from opaque to transparent, or transparent to opaque to transparent, with the use of an applied electrical bias).

[0080] Related electrochromic devices prepared according to embodiments of the present invention may include, but are not limited to, electrochromic windows and electrochromic sunroofs.

[0081] The present invention allows for electrochromic devices having a rigid curved surface on one substrate to be combined with a flexible substrate. In such an embodiment, the electrochromic device includes a first substrate that is flexible and a second substrate that is rigid. In another embodiment, the electrochromic device includes a first substrate that is rigid and a second substrate that is flexible.

[0082] The present invention will now be described with reference to specific examples. It will be understood that the following examples are intended to illustrate embodiments of the present invention and are not intended to limit the present invention in any way. It will be understood that certain aspects of the disclosed processes can be arranged and combined in a wide variety of different configurations.

[0083] Working Example Example 1 - Preparation of electrochromic WOx on curved surfaces A 12" x 12" fluorine-doped tin oxide (FTO) coated glass substrate (TEC 10; 10 Ω / sq) (Pilkington, Toledo, OH, USA) was bent to a radius of curvature of 2 meters measured at the center of the assembled electrochromic device (Coastal Curved Glass, Pitt Meadows, BC, Canada). The curved substrate was ultrasonically cleaned successively for 15 minutes each in the following solutions: Extran® 300 detergent (VWR, Mississauga, ON, Canada); deionized H2O; acetone (VWR Canada, Mississauga, ON, Canada); and 2-propanol (VWR, Mississauga, ON, Canada). The substrate was dried and the concave surface was raster treated with atmospheric pressure plasma for 5-8 minutes. All four sides of the concave surface of the cleaned substrate were masked and the substrate was spray coated. For the precursor solution, 2-propanol (VWR, Mississauga, Ontario, Canada) was added to tungsten(VI) chloride (WCl6, Sigma Aldrich, Oakville, Ontario, Canada) to give a 0.05 M solution. This solution was filtered and spray-coated (arm speed = 10 cm / s) onto a curved FTO-coated glass substrate to give a blue layer on the substrate. This spraying process was repeated two more times. The coated substrate was then placed in a UV reactor (dual wavelength (λ = 185, 254 nm) UV lamp (05-0332-R GPH436T5VH / HO / 4PSE, 4-pin ozone, Atlantic Ultraviolet, Hauppauge, NY, USA) for 5 min. The precursor was converted to form WOx. The cast film changed from blue to colorless and was converted to a film made of metal oxide, in this case WOx. The spray and UV process was repeated six times. The mask was removed. The conversion of the precursor was followed by X-ray fluorescence (XRF) spectroscopy and was considered complete when the counts corresponding to the chloride ligands of the precursor disappeared or reached a baseline level.

[0084] Example 2 - Preparation of electrochromic NiOx on curved substrates A 12" x 12" fluorine-doped tin oxide (FTO) coated glass substrate (TEC10; 10 Ω / sq) (Pilkington, Toledo, OH, USA) was bent to a radius of curvature of 2 meters measured at the center of the assembled electrochromic device (Coastal Curved Glass, Pitt Meadows, BC, Canada). The curved substrate was ultrasonically cleaned successively for 15 minutes each in the following solutions: Extran® 300 detergent (VWR, Mississauga, ON, Canada); deionized H2O; acetone (VWR Canada, Mississauga, ON, Canada); and 2-propanol (VWR, Mississauga, ON, Canada). The substrate was dried and the convex surface was rastered with atmospheric pressure plasma for 5-8 minutes. All four sides of the cleaned convex surface of the substrate were masked and the substrate was spray coated. For the precursor solution, 2-propanol (VWR, Mississauga, Ontario, Canada) was added to nickel(II) 2-ethylhexanoate (78% in 2-ethylhexanoic acid) ((Ni(eh)2), Strem, Newburyport, Massachusetts, USA) to give a 0.18 M solution. This solution was filtered and spray-coated (arm speed = 10 cm / s) onto a curved FTO-coated glass substrate, resulting in a colorless layer on the substrate. This spray process was repeated five times. The mask was removed. The substrate was then placed in an oven (Memmert UF 160 The coated substrate was then masked again and sprayed (three times) with a 0.20 M solution of the nickel precursor. The mask was removed and the coated substrate was placed in an oven for conversion to the oxide (oven conditions were the same as above). This spray / oven process was repeated one more time with the 0.20 M solution. The conversion of the precursor was followed by Fourier transform infrared fluorescence (FTIR) spectroscopy and was considered complete when the stretches corresponding to the corresponding precursor ligands disappeared or reached baseline levels.

[0085] Example 3 - Curved electrochromic device In this example, the electrochromic WOx layer prepared as described in Example 1 and the NiOx layer described in Example 2 were incorporated into a liquid electrochromic device with the structure of glass / FTO / WOx / LiClO4 in PC / FTO / glass.

[0086] A copper tape (McMaster-Carr, Robbinsville, NJ, USA) busbar was attached to the bare FTO along the two connected edges on the coated side of the WOx substrate, and silver paint (Ted Pella, Redding, CA, USA) was applied along the edge of the copper tape in contact with the FTO.

[0087] Copper tape (McMaster-Carr, Robbinsville, NJ, USA) busbars were attached to the bare FTO along the two connected edges on the coated side of the NiOx substrate (so that the entire device appears covered with copper tape).

[0088] Double-sided 3M™ VHB™ tape (4910, 3 / 4 inch, 40 mil) was applied around the outer periphery of one of the coated electrodes, sandwiching the two electrodes together with the coated sides facing each other to complement the curvature. The VHB™ tape was wide enough to cover the busbars to prevent electrolyte from contacting the busbars. The edges were pressed to create a good seal.

[0089] A 1 M solution of battery grade lithium perchlorate (LiClO4, Sigma Aldrich, Oakville, Ontario, Canada) in anhydrous propylene carbonate (PC, Sigma Aldrich, Oakville, Ontario, Canada) was injected into the cell using a syringe and blunt needle. This was done carefully to avoid introducing air bubbles into the device. A second blunt needle was inserted on the other side to act as a vent when injecting the electrolyte. After filling, the needle was removed.

[0090] The electrochromic performance of the described electrochromic device was tested by a combined UV-Vis spectroscopy and electrochemistry setup. The potentiostat lead of the working electrode was connected to a copper tape bus bar in contact with the FTO on the coated WOx electrode. The counter and reference electrodes were connected to copper tape bus bars in contact with the FTO on the coated NiOx electrode. A series of voltages of -1.7 V and +1.7 V were applied to the device, alternating with an interval of 300 s, and the switching time of the device (bleach to colored, colored to bleach) was measured. The change in transmittance in the CIE Y scale of the electrochromic device as a function of time was recorded. Figure 2 shows a sample of 30 switching cycles of the device.

[0091] All U.S. patents, U.S. patent applications, foreign patents, foreign patent applications, and non-patent literature referred to herein are hereby incorporated by reference in their entirety to the extent such incorporation is permitted.

[0092] While specific elements, embodiments and applications of the invention have been shown and described, it will of course be understood that the invention is not limited to the foregoing teachings, since modifications may be made by those skilled in the art without departing from the spirit and scope of the present disclosure, particularly in light of the foregoing teachings. Such modifications are deemed to fall within the scope of the appended claims.

Claims

1. 1. A method of manufacturing a curved electrochromic device, comprising the steps of: providing a first curved substrate having a first transparent conductive coating on one surface; coating the first transparent conductive coating with a cathodic electrochromic metal oxide layer, wherein the cathodic electrochromic metal oxide layer is formed by the following steps: i) spray-coating a first transparent conductive coating on a first curved substrate with a first solution comprising one or more inorganic or organometallic cathode precursors to form a first precursor layer; and ii) exposing the first precursor layer to near infrared light, ultraviolet light, or ozone to convert the one or more inorganic or organometallic cathode precursors into a cathodic electrochromic metal oxide layer and form a first coated curved substrate; formed by a process including: providing a second curved substrate having a second transparent conductive coating on one surface thereof, wherein the second curved substrate has a curvature complementary to the first curved substrate; coating the second transparent conductive coating with an anodic electrochromic metal oxide layer, wherein the anodic electrochromic metal oxide layer is formed by the following steps: iii) spray coating the second transparent conductive coating on the second curved substrate with a second solution comprising one or more inorganic or organometallic anode precursors to form a second precursor layer; and iv) exposing the second precursor layer to near infrared, ultraviolet, or ozone radiation to convert the one or more inorganic or organometallic anodic precursors into an anodic electrochromic metal oxide layer and form a second coated curved substrate; formed by a process including: incorporating an electrolyte layer between the cathodic electrochromic metal oxide layer on the first coated curved substrate and the anodic electrochromic metal oxide layer on the second coated curved substrate to obtain a layered structure; and sealing the layered structure to form a curved electrochromic device, wherein the sealing step can be performed before or after incorporation of the electrolyte; A method comprising:

2. 2. The method of claim 1, wherein steps i) and ii) and / or steps iii) and iv) are repeated until a desired thickness of the cathodic electrochromic metal oxide layer and / or a desired thickness of the anodic electrochromic metal oxide layer is achieved.

3. 10. The method of claim 1, wherein step i) is repeated more than once before step ii).

4. 10. The method of claim 1, wherein the spray coating of step i) and / or step iii) is performed with a spray coater nozzle moving over the first and / or second curved substrate to provide a uniform coating of one or more inorganic or organometallic precursors.

5. The method of claim 4, wherein the spray coater nozzle travels between 20 feet and 50 feet per minute.

6. 2. The method of claim 1, wherein the spray coating of step i) and / or step iii) is performed using a spray coater nozzle to provide a uniform coating of one or more inorganic or organometallic precursors, wherein the spray coater nozzle is stationary and the first and / or second curved substrates move below the stationary nozzle.

7. The method of claim 1 , wherein the cathodic electrochromic metal oxide layer and / or the anodic electrochromic metal oxide layer is annealed after step ii) and / or step iv).

8. 8. The method of claim 7, wherein the annealing step is performed at a temperature of from about 30°C to about 600°C.

9. The method of claim 1 , wherein the curved electrochromic device comprises at least one region having a radius of curvature of about 300 mm to about 4000 mm.

10. the curved electrochromic device is a single curved electrochromic device; or the curved electrochromic device is a compound curved (double curved) electrochromic device; or The method of claim 1 , wherein the curved electrochromic device is a complex curved electrochromic device.

11. The method of claim 1 further comprising providing an additional layer to the cathodic electrochromic metal oxide layer and / or the anodic electrochromic metal oxide layer.

12. 12. The method of claim 11, wherein the additional layer is a barrier layer comprising niobium oxide, lithium oxide, titanium oxide, tantalum oxide, cerium oxide, aluminum oxide, zirconium oxide, or a mixture thereof.

13. The method of claim 11 , wherein the additional layer is a barrier layer comprising niobium oxide, zirconium oxide, lithium oxide, or a combination thereof.

14. 10. The method of claim 1, wherein the cathodic electrochromic metal oxide layer and the anodic electrochromic metal oxide layer comprise a metal oxide selected from the group consisting of NiOx, WOx, MoOx, TiOx, TaOx, VOx, NbOx, CoOx, IrOx, MnOx, FeOx, LiNiOx, WNbOx, TiWOx, LiWOx, NiNbOx, NiNbLiOx, NiAlLiOx, or any combination thereof.

15. 15. The method of claim 14, wherein the cathodic electrochromic metal oxide layer comprises WOx, WNbOx, TiWOx, LiWOx, MoOx, TiOx, TaOx, NbOx, or any combination thereof.

16. 15. The method of claim 14, wherein the anodic electrochromic metal oxide layer comprises NiOx, LiNiOx, NiNbOx, NiNbLiOx, NiAlLiOx, CoOx, IrOx, MnOx, FeOx, VOx, or any combination thereof.

17. 15. The method of claim 14, wherein the cathodic electrochromic metal oxide layer and / or the anodic electrochromic metal oxide layer is a metal oxide layer doped with dopant atoms selected from niobium, cerium, aluminum, lithium, tantalum, molybdenum, cobalt, silicon, and titanium.

18. The method of claim 14, wherein the cathodic electrochromic metal oxide layer and / or the anodic electrochromic metal oxide layer each have an average thickness of about 10 nm to about 2000 nm.

19. The method of claim 1 , wherein the electrolyte layer is an electrolyte solution.

20. 20. The method of claim 19, wherein the electrolyte is a solution of a lithium salt in propylene carbonate.

21. The electrolyte layer comprises: polymer resin; Lithium salts; a solvent content comprising one or more solvents; optionally, a plasticizer component; and optionally a cross-linking agent, The method of claim 1 , wherein the polymer gel comprises:

22. The electrolyte layer comprises: difunctional oligomers; monofunctional monomers; Lithium salts; optionally, a plasticizer component; and optionally a photoinitiator; The method of claim 1 , wherein the polymer gel comprises:

23. The method of claim 1 , wherein the electrolyte layer is a solid layer comprising at least one ion-conducting metal oxide.

24. 10. The method of claim 1, wherein the first and / or second solutions of one or more inorganic or organometallic precursors comprise one or more of inorganic chlorides, inorganic nitrates, inorganic acetates, inorganic oxalates, organometallic 2-ethylhexanoates, organometallic butoxides, organometallic ethoxides, organometallic methoxides, organometallic isopropoxides, organometallic acetylacetonates, organometallic silanolates, organometallic oxalates, or mixtures thereof.

25. 10. The method of claim 1, wherein the first and second curved substrates are independently selected from the group consisting of glass, polyethylene terephthalate (PET), polycarbonate, polyethylene naphthalate (PEN), polyvinyl butyral (PVB), polymethyl methacrylate (PMMA), acrylic, clear acrylonitrile butadiene styrene (ABS), methyl methacrylate acrylonitrile butadiene styrene (MABS), polyvinyl chloride (PVC), amorphous copolyester (PETG), general purpose polystyrene, styrene acrylonitrile resin (SAN), styrene methyl methacrylate (SMMA), fluorinated ethylene propylene (FEP), clear polypropylene, ionomer resin, polyethylene (PE), cyclic olefin copolymer, thermoplastic polyurethane (TPU), and liquid silicone rubber (LSR).

26. The method of claim 1 , wherein the first and second curved substrates are both glass.

27. 27. The method of claim 26, wherein the glass is tempered or heat-strengthened glass.

28. The method of claim 1 , wherein the first and second curved substrates are independently glass, polycarbonate, polyethylene terephthalate, or polyethylene naphthalate.

29. 10. The method of claim 1, wherein the first and / or second transparent conductive coating comprises fluorine tin oxide (FTO), indium tin oxide (ITO), aluminum zinc oxide (AZO), silver mesh, silver nanowires, silver nanoparticles, carbon nanotubes, carbon black, graphene, a conductive polymer, or a mixture of two or more thereof.

30. 10. A curved electrochromic device manufactured using the method of claim 1.

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