Electrochromic double layer device with dynamic light throughput control and its fabrication process

Abstract

Broadband electrochromic devices (ECDs) with independent band selectivity over visible and near-infrared (NIR) radiation have attracted much attention due to their functional benefits over conventional ECDs. The independent dual-band activity of ECDs usually requires special structuring by blending / layering different materials active in two different regions. The present invention provides a broadband electrochromic device comprising a polycrystalline nanosheet layer and a polycrystalline porous layer. Here, we demonstrate that employing a same-material dual-layer electrode, i.e., a porous a-WO3 layer on top of polycrystalline WO3·H2O nanosheets, achieves very good visible light modulation with unprecedented NIR blocking performance. This simple and inexpensive electrode preparation may provide a new platform for realizing high-performance dynamic smart glass with extremely high spectral selectivity and energy saving.

Description

[Technical Field]

[0001] The present invention relates to electrochromic devices, electrochromic coatings, and device fabrication that provide dynamic light throughput control. Specifically, the present invention relates to electrochromic bilayer coatings that provide exceptionally high broadband light modulation spanning the visible to infrared wavelength range, where the bilayer modulation wavelength is voltage selective. More particularly, the present invention also relates to a process for fabricating electrochromic devices using the bilayer film electrodes described above. [Background technology]

[0002] Electrochromism is defined as the reversible change in optical properties upon application of a voltage. Electrochromic materials are utilized in electrochemical devices to modulate transmittance, reflectance, absorbance, or emittance. A typical electrochromic device (ECD) is constructed by sandwiching an ion-conducting electrolyte between two sheets of transparent, electrically conductive, oxide-coated glass (TCO / glass), preferably with an active layer laminated to at least one of the two sheets. The use of a complementary electrochromic coating on the other electrode is optional, providing more stable, neutral color rendering, etc. Figure 1 shows a schematic cross-section of an ECD, with the cathode and anode electrochromic coatings applied to the complementary substrates. The electrolyte membrane is designed to prevent the two electrodes from being electrically shorted, thereby preventing the ions (M + ) conductivity and electron (e - ) blocking properties are desirable. The electrochromic layer changes color or color when a suitable voltage pulse is applied, while the counter electrode layer functions as an ion accumulation / absorption layer. Coloring efficiency, modulation wavelength range, response time, and write-erase efficiency are some of the performance evaluation criteria for ECDs.

[0003] Reference may be made to French Patents Nos. 2969323A1 / 2969323B1, which describe a solid-state infrared active electrochromic device with double layer electrodes.

[0004] Reference may be made to International Patent Application No. PCT / US2012 / 047935, and WO 3-x Nanocrystalline a-NbO x Dynamic (visible and NIR modulated) ECDs have been reported by constructing glass blends.

[0005] Reference may be made to the articles "DJ Milliron et al., Nature 2013, 500, 323; DJ Milliron et al., Chem. Commun. 2014, 50, 10555; DJ Milliron et al., Adv. Opt. Mater. 2013, 1, 215," in which plasmonic electrochromic (EC) nanocrystals of transparent conducting oxides (TCOs) (such as indium-doped tin oxide or aluminum-doped zinc oxide) that exhibit high-contrast NIR modulation are developed and blended with visually modulating components.

[0006] Reference may be made to the paper "H. Gu et al., ACS Nano, 2018, 12, 559," in which crown-type polyoxometalates (K 28 Li5H7P8W 48 O 184 -92H2O) and W 18 O 49 Voltage-selective EC modulation zones are demonstrated using electrodes fabricated by sequentially depositing nanowires.

[0007] Reference may be made to the paper "Z. Wang et al., Adv. Opt. Mater. 2017, 5, 1700194," in which the second layer (W 18 O 49A simplified approach is presented by utilizing the inherent structural tunnels of the top layer (Prussian blue) to facilitate the accommodation and transport of ions that can induce NIR modulation in ZnSe.

[0008] Reference may be made to Korean Patent No. 201701702A, which relates to an electrochromic device with improved electrochromic speed and durability and a manufacturing method thereof. The electrochromic device sequentially comprises a first substrate, a first electrode layer, an electrochromic layer, an electrolyte layer, an ion storage layer, and a second electrode layer.

[0009] In the present invention, an electrochromic device has been developed by combining nanocrystalline and amorphous WO electrochromic layers together. The disclosed invention provides benefits and novelty by avoiding many of the processing and operational drawbacks described in the prior art. In addition, the present invention also describes a process for selecting electrochromic materials so that they can be effectively layered to enhance device functionality.

[0010] The novelty of this invention lies in the description of a process for screening / selecting electrochromic materials so that they can be effectively deposited as layers to enhance device functionality. Furthermore, the use of these materials to fabricate electrochromic devices does not exist in the prior art. Also, the deposition sequence for creating spectrally selective electrodes does not exist in the prior art.

[0011] Abbreviations used a-WO3- amorphous tungsten oxide WO3- Tungsten oxide ECD - Electrochromic Device TCO - Transparent Conductive Oxide FTO - Fluorine-doped tin oxide LiClO4 - Lithium perchlorate NIR - Near Infrared PC - Propylene Carbonate PMMA - Polymethyl methacrylate THF - tetrahydrofuran SPE - Solid Polymer Electrolyte XRD - X-ray diffraction SEM - Scanning Electron Microscope TEM - Transmission Electron Microscope Object of the invention

[0012] The main objective of the present invention is to provide an electrochromic double layer electrode by stacking two different electrochromic layers with different spectral selectivities driven by different voltages.

[0013] Another object of the present invention is to provide an electrochromic overcoating layer that effectively enables the utilization of electrolyte ions by the bottom layer.

[0014] It is yet another object of the present invention to provide an electrochromic undercoating layer that has both an operating voltage and a spectral wavelength offset compared to the top layer.

[0015] It is yet another object of the present invention to provide a dynamic, spectrally selective ECD with highly efficient visible and infrared modulation. Summary of the Invention [Means for solving the problem]

[0016] Thus, the present invention provides: i. a conductive substrate consisting of a substrate

[15] coated with a transparent conductive oxide [TCO]

[13] ; ii. an electrochromic layer

[11] coated on a conductive substrate; iii. an electrochromic layer

[12] deposited on the electrochromic layer

[11] ; 1. A double layer electrochromic electrode comprising: A double-layer electrochromic electrode is provided, in which the thickness of the electrochromic layers [11 and 12] ranges from 10.0 nm to 3.0 μm.

[0017] In one embodiment of the present invention, the substrate is selected from the group consisting of glass, quartz, cellulose, silk, and plastics selected from the group consisting of polythene, polyimide, polyacrylate, polycarbonate.

[0018] In another embodiment of the present invention, the conductive substrate has a sheet resistance range of from 1.0 μΩ / sq to 50.0 Ω / sq.

[0019] In yet another embodiment of the present invention, the transparent conductive oxide [TCO] is selected from the group consisting of indium zinc oxide (IZO), indium tin oxide (ITO), fluorine doped tin oxide (FTO), fluorine doped zinc oxide (FZO), aluminum doped zinc oxide (AZO), and aluminum doped tin oxide (ATO).

[0020] In yet another embodiment of the present invention, the electrochromic layers [11 and 12] are selected from the group consisting of organic compounds such as viologens, thiophenes, fluorenes, metal complexes such as bipyridene complexes, terpyridine complexes, conjugated polymers such as polythiophenes, polypyrroles, polyanilines, polycarbazoles, pure and sub-stoichiometric metal oxides such as WO3, TiO2, MoO3, NiO, VO5, ZnO, Ta2O5, Cr2O3, MnO2, Fe2O3, CoO2, RhO2, IrO2, Nb2O5, and combinations / hybrids thereof.

[0021] In yet another embodiment of the present invention, the electrochromic layer

[12] can even have the same chemical composition as the electrochromic layer

[11] but different crystallinity, porosity, or dopant / additive concentration.

[0022] In yet another embodiment of the present invention, the electrochromic layer

[12] has the same voltage polarity response (cathodic, anodic, or dual) as the electrochromic layer

[11] .

[0023] In yet another embodiment, the present invention provides: a. Double layer electrochromic electrode [active electrode]; b. an electrolyte, i.e., an ion-conducting layer

[10] placed on the electrochromic layer

[12] of the active electrode; c. a counter electrode placed over the exposed side of the electrolyte, comprising a conductive substrate made of a transparent conductive oxide [TCO]

[14] coated transmissive or reflective substrate

[16] ; The present invention provides a dual layer electrochromic device comprising:

[0024] In yet another embodiment of the present invention, the counter electrode is optionally coated with a complementary coating consisting of a different electrochromic layer with an opposite voltage polarity response to the active electrode.

[0025] In yet another embodiment of the present invention, the conductive substrates of the active and counter electrodes are electrically connected to terminals having opposite polarities.

[0026] In yet another embodiment of the present invention, the device exhibits a color change upon application of a voltage in the range of ±0.5 to ±10.0 V relative to a counter electrode.

[0027] In yet another embodiment of the present invention, if the undercoating and complementary coating are spectrally unresponsive at applied voltage values ​​when used at either polarity, the device will exhibit the spectral response of the overcoating, and vice versa.

[0028] In yet another embodiment of the present invention, the solution / dispersion / polymer film is + , Na + , K. + , and Al3 +Either the salt of the system or a mixture thereof is incorporated.

[0029] Yet another embodiment of the present invention exhibits overlapping spectral responses resulting from the undercoating, overcoating, and complementary coating when subjected to a voltage ranging from ±0.5 to ±10.0 V relative to the counter electrode (when used for the counter electrode).

[0030] In yet another embodiment, the present invention provides: a. dissolving tungsten powder in 50% H2O2 with stirring for a period ranging from 24 to 36 hours, and then filtering to obtain a clear, colorless liquid; b. Decomposing the excess hydrogen peroxide from the liquid obtained in step (a) by stirring at a temperature ranging from 80 to 90°C for a period ranging from 4 to 6 hours to obtain a deep yellow solution; c. drying the solution obtained in step (b) to obtain tungsten oxide hydrate powder; d. dispersing the tungsten oxide hydrate powder obtained in step (c) in water, followed by ultrasonic treatment for a period ranging from 7 to 10 hours to obtain a solution of tungsten oxide hydrate [WO3·H2O]; e. dispersing the tungsten oxide hydrate powder obtained in step (c) in a 10% H2O2 aqueous solution, followed by ultrasonic treatment for a period ranging from 7 to 10 hours to obtain a solution of a-WO3; f. drop-casting 20-30 μL of the solution obtained in step (d) onto a clean FTO substrate, followed by evaporation at a temperature ranging from 50 to 80°C for a period ranging from 15 to 30 minutes to obtain a polycrystalline layer 1 of WO3·H2O with a thickness ranging from 800 to 1000 nm; g. drop-casting 20-30 μL of the solution obtained in step (e) onto the uniform film obtained in step (i), followed by evaporation at a temperature in the range of 50-80° C. for a period in the range of 15-30 minutes to obtain a porous amorphous layer 2 of a-WO3 with a thickness in the range of 600-1000 nm; A process for producing a dual layer electrochromic electrode comprising:

[0031] In yet another embodiment, the present invention provides: a. dissolving anhydrous LiClO4, a plasticizer, and PMMA in a solvent selected from the group consisting of tetrahydrofuran [THF], chloroform, DCM, DMSO, DMF, toluene, ethyl acetate, diethyl ether, acetonitrile, carbon tetrachloride, 2-propanol, hexane, benzene, and acetone, and then stirring at a temperature ranging from 60 to 80°C for a period ranging from 12 to 24 hours to obtain a homogeneous mixture; b. evaporating the solvent under a dry nitrogen stream at a temperature in the range of 80-90°C to obtain a solid polymer electrolyte; c. stacking the polycrystalline WO3.H2O nanosheets and the porous a-WO3 layer to obtain an active electrode; d. embedding the solid polymer electrolyte obtained in step (b) having a thickness ranging from 130 to 250 μm between an active electrode and a reflective electrode to obtain an electrochromic device;

[0013] A process for making an electrochromic device is provided, comprising:

[0032] In yet another embodiment of the present invention, the plasticizer is selected from the group consisting of propylene carbonate; 4-(hydroxymethyl)-1,3-dioxolan-2-one; carbonic acid dibutyl ester; 1-(3-hydroxypropyl)-2-pyrrolidone; 1-octyl-2-pyrrolidone; 5-dodecanolide; 1-hexyl-3-methylimidazolium chloride; 1-methyl-3-octylimidazolium chloride; 2,2-dimethyl-1,3-hexanediol; 2-methyl-1,3-pentanediol; 1 -Cyclohexyl-2-methyl-1,3-pentanediol;2,4-diethyl-1,5-pentanediol;1,3-nonanediol;2-butyl-1,3-octanediol;3-methylpentane-1,3,5-triol;2-ethyl-1,3-hexanediol;benzyl alcohol;3-methyl-1,5-pentanediol;1-phenoxy-2-propanol;2-(2-butoxyethoxy)ethanol;Bis(2-ethylhexyl) phosphate;Tributyl phosphate; and tris(2-ethylhexyl) phosphate; linear carbonates; cyclic carbonates; linear primary alcohols; linear and branched aliphatic diols, linear and branched aliphatic triols; benzyl alcohol; linear and cyclic ureas; linear or cyclic urethanes; thioureas; thiourethanes; linear thio-oxocarbonates; pyrrolidon-2-ones; dihydrofuran-2-ones; piperidin-2-ones, or pyran-2-ones.

[0033] In yet another embodiment of the present invention, the device is useful in smart windows, smart mirrors, e-paper, smart displays, helmet visors, smart eyeglasses, optical data storage, glare reduction device configurations, thermal and optical transmission modulators, and integrated charge storage devices. [Brief explanation of the drawings]

[0034] [Figure 1] FIG. 1 shows a schematic cross-section of an ECD having cathodic and anodic electrochromic coatings on complementary substrates. [Figure 2]FIG. 2 shows a schematic diagram of an electrochromic device assembly using polycrystalline WO3·H2O nanosheets of the present invention, designated Device 1. [Figure 3] FIG. 3 shows a schematic diagram of an electrochromic device assembly using porous a-WO 3 of the present invention, designated Device 2. [Figure 4] FIG. 4 shows a schematic diagram of a dual layer electrochromic device assembly of the present invention, designated Device 3. [Figure 5] Figure 5 shows the XRD images of polycrystalline WO3·H2O nanosheets and porous a-WO3 materials on quartz substrates of the present invention. [Figure 6] Figure 6 shows an AFM image of the polycrystalline WO3·H2O nanosheets of the present invention. [Figure 7] FIG. 7 shows an AFM image of the porous a-WO3 of the present invention. [Figure 8] Figure 8 shows a TEM image of polycrystalline WO3·H2O nanosheets of the present invention. [Figure 9] FIG. 9 shows a TEM image of the porous a-WO3 of the present invention. [Figure 10] FIG. 10 shows an SEM image of a bilayer of the present invention. [Figure 11] Figure 11 shows the cyclic voltammetry plots of the electrochromic device fabricated using polycrystalline WO3·H2O nanosheets. [Figure 12] Figure 12 shows the transmittance plot of the electrochromic device fabricated using polycrystalline WO3·H2O nanosheets. [Figure 13] Figure 13 shows the cyclic voltammetry plots of the electrochromic device fabricated using the porous a-WO3 layer. [Figure 14] FIG. 14 shows the transmittance plot of the electrochromic device fabricated using a porous a-WO3 layer. [Figure 15]Figure 15 shows the cyclic voltammetry plots of the electrochromic bilayer device fabricated using polycrystalline WO3·H2O nanosheets and a porous a-WO3 layer. [Figure 16] Figure 16 shows the transmittance plot of the electrochromic bilayer device fabricated using polycrystalline WO3·H2O nanosheets and a porous a-WO3 layer. DETAILED DESCRIPTION OF THE INVENTION

[0035] The present invention demonstrates a novel scheme to fabricate a broadband ECD with independent dual band selectivity across visible and NIR radiation.

[0036] This disclosure relates to the fabrication of high quality, wide spectral range, and spectrally selective electrochromic electrodes and devices. This goal is achieved by stacking two similar / dissimilar electrochromes with specific morphologies.

[0037] For the transparent electrode, a substrate of electrochromic electrode material consisting of the group consisting of glass, quartz, cellulose, silk, and plastic (e.g., polythene, polyimide, polyacrylate, polycarbonate, etc.) To make a reflective electrode, the substrate is further coated on one or both sides with a material selected from a metal coating consisting of coatings of chromium, silver, gold, tantalum, titanium, etc.

[0038] The transparent (or reflective) electrode is coated with a conductive coating material from the group consisting of indium zinc oxide (IZO), indium tin oxide (ITO), fluorine-doped tin oxide (FTO), fluorine-doped zinc oxide (FZO), aluminum-doped zinc oxide (AZO) and aluminum-doped tin oxide (ATO), conductive metal coatings, and mixtures / hybrids thereof.

[0039] The conductive coating has a sheet resistance range of 1.0 μΩ / sq to 50.0 Ω / sq.

[0040] Electrolyte baths for the test electrodes were prepared using a liquid electrolyte made from a solution / dispersion containing a salt selected from the group consisting of H2SO4, LiCIO4, ZnCl2, LiBf4, LiAsF6, LiI, LiBr, LiCF3SO3, LiTFSI, KYF4, KNO3, KBrO3, KI, KBF4, KOH, KSCN, K2Cr2O7, KCl, KCH3CO2, NHClSCN, NH4CH3CO2, NH4Br, NH4Cl, NaSCN, NaPF6, NaYF4, and mixtures / hybrids / combinations thereof.

[0041] The conductive coating of the electrode is further coated with an electrochromic material to create the active electrode, the material being: (i) transition metal oxides selected from the group consisting of WO3, TiO2, MoO3, NiO, V2O5, Fe2O3, Ta2O5, Cr2O3, MnO2, FeO2, CoO2, RhO2, IrO2, Nb2O5, etc.; (ii) other metal oxides selected from the group consisting of SnO2, Bi2O3, and Pb3O4; (iii) an organic molecule selected from the group consisting of viologens, thiophenes, fullenes, etc.; (iv) a metal complex selected from the group consisting of bipyridine complexes, terpyridine complexes, and the like; (v) conjugated polymers selected from the group consisting of polythiophenes, polypyrroles, polyanilines, polycarbazoles, and the like; (vi) combinations and hybrids thereof; is selected from the group consisting of:

[0042] The electrochromic coating has a thickness in the range of 10.0 nm to 3.0 μm.

[0043] The electrochromic coating exhibits a color change while immersed in an electrolyte solution under the application of a suitable voltage, for example, 0.1 to 3.0 V, relative to an Ag / AgCl reference electrode.

[0044] The electrochromic coating on the electrode is further covered with a second electrochromic layer, the material of which has a different electrochromic response than the first layer but responds to the same voltage polarity. The material of the second electrochromic layer is selected from the group described in the previous embodiment, but has sufficient discontinuities to allow the first electrochromic layer to utilize electrolyte ions. The chemical composition of this second electrochromic layer can be selected to be similar to that of the first electrochromic layer, but with a different electrochromic response that can be achieved through changes in phase, crystallinity, morphology, dopant concentration, etc.

[0045] The second electrochromic coating has a thickness in the range of 10.0 nm to 3.0 μm.

[0046] The second electrochromic coating exhibits a color change while immersed in an electrolyte solution under the application of a suitable voltage, for example, 0.1 to 3.0 V, relative to an Ag / AgCl reference electrode.

[0047] The conductive electrodes are optionally coated with a material selected from the group described in the previous embodiment, but respond to a voltage polarity opposite to that of the active electrode. These electrodes, with or without the complementary coating described above, were used as counter electrodes in the device setup.

[0048] Electrochromic devices were fabricated using liquid / gel / solid electrolytes made from solutions / dispersions / polymer films containing salts selected from the group consisting of LiCIO4, ZnCl2, LiBf4, LiAsF6, LiI, LiBr, LiCF3SO3, LiTFSI, KYF4, KNO3, KBrO3, KI, KBF4, KOH, KSCN, K2Cr2O7, KCl, KCH3CO2, NHClSCN, NH4CH3CO2, NH4Br, NHCl, NaSCN, NaPF6, NaYF4, and mixtures / hybrids / combinations thereof.

[0049] The electrochromic device was fabricated by sandwiching an electrolyte layer (described in the previous embodiment) between an active electrode and a counter electrode. The electrolyte formed a continuous, uniform interface that electrically connected a second electrochromic layer on one side and the conductive surface of the counter electrode (optionally with a complementary coating) on ​​the other side. The device's mechanism can be achieved by using a spacer to prevent electrical shorting between the active and counter electrodes. The device can be completely sealed with a sealant for weather resistance. The active and counter electrodes are electrically connected to opposite terminals of a voltage source.

[0050] The device exhibits a color change upon application of a suitable voltage, for example, 0.5 to 10.0 V, relative to the counter electrode.

[0051] The device exhibits overlapping spectral responses resulting from the first and second (and complementary coatings at the counter electrode, if used) electrochromic coatings. The device exhibits a spectral response similar to the first electrochromic coating if the second electrochromic (and complementary) coating is spectrally unresponsive at the applied voltage value. The device exhibits a spectral response similar to the second electrochromic coating if the first electrochromic (and complementary) coating is spectrally unresponsive at the applied voltage value.

[0052] Electrochromic devices exhibit spectral band selectivity, provided suitable materials are selected that have electrochromic responses in different spectral ranges with different bias requirements.

[0053] Electrochromic electrodes have individual electrodes fabricated by directly depositing either an overcoating or an undercoating on a conductive substrate, where, for example, an electrode with only the overcoating or only the undercoating exhibits a color change while immersed in an electrolyte solution with a suitable voltage applied, e.g., ±0.1 to ±3.0 V, relative to an Ag / AgCl reference electrode, where the color change of the overcoating-only electrode is different from that of the undercoating-only electrode at the same applied voltage value, and the polarity of the applied voltage depends on the voltage polarity response of the material used in the undercoating or overcoating, e.g., (-) for cathodic electrochromic materials, (+) for anodic electrochromic materials, and either for dual electrochromic materials.

[0054] The electrolyte in which the electrodes were immersed for color switching was H2SO4 or Li + , Na + , K. + , and Al 3+ The compound contains either a salt of the system or a mixture thereof.

[0055] The electrode exhibits overlapping spectral responses arising from both the undercoating and overcoating while immersed in the electrolyte solution and subjected to ±0.1 to ±3.0 V.

[0056] The electrode will exhibit the spectral response of the undercoating if the overcoating is spectrally unresponsive at the applied voltage value, and vice versa.

[0057] The electrolyte is H2SO4 or Li + , Na + , K. + , Al3+ The system has a solution / dispersion / polymer film incorporating either the salt or a mixture thereof.

[0058] The undercoating and complementary coating used on the counter electrode will exhibit the spectral response of the overcoating if either is spectrally unresponsive at the applied voltage values ​​when used in an electrochromic device, and vice versa.

[0059] An electrochromic device exhibiting overlapping spectral responses resulting from the undercoating, overcoating, and complementary coating when subjected to a voltage ranging from ±0.5 to ±10.0 V relative to the counter electrode (when used as the counter electrode).

[0060] etc. for the transparent electrode, and coated on one or both sides with a metal (chromium, silver, gold, tantalum, titanium etc.) coating for the reflective electrode.

[0061] 2 and 3 show cross-sectional views of electrochromic devices 1 and 2, respectively, while FIG. 4 shows a cross-sectional view of an electrochromic device 3 of the present invention. Electrochromic device 3 comprises an ion conductor layer 10. Electrode layer 12 is in contact with ion conductor layer 10, and electrode layer 11 is in contact with electrode layer 12. Layers 11 and 12 comprise electrochromic materials. Layers 10, 11, and 12 are positioned between conductive layers 13 and 14, which are disposed on external substrates 15 and 16. Layers 10, 11, 12, 13, and 14 are collectively referred to as an electrochromic stack, 17.

[0062] Conductive layer 13 is in electrical contact with one terminal of a power supply, and conductive layer 14 is in electrical contact with the other terminal of the power supply, whereby the transmittance of electrochromic device 3 may be changed by applying a voltage pulse to conductive layers 13 and 14. This pulse causes electrons and ions to move between electrode layers 11 and 12 and ion-conducting layer 10. As a result, the electrochromic materials of the first and second electrode layers change optical states, thereby switching electrochromic device 3 from a bleached state to a colored state, or from a colored state to a bleached state.

[0063] The term "bleached" should be understood to refer to an optically neutral state, e.g., uncolored, transparent, or translucent. Furthermore, unless otherwise specified herein, the "color" of the electrochromic transition is not limited to a particular wavelength or range of wavelengths. As will be understood by those skilled in the art, the selection of appropriate electrochromic and counter electrode materials will determine the associated optical transition. Generally, the change in transmittance comprises a change in transmittance for electromagnetic radiation, preferably having wavelengths ranging from infrared to ultraviolet radiation. For example, in one embodiment of the present invention, the change in transmittance is primarily for electromagnetic radiation in the infrared spectrum. In another embodiment of the present invention, the change in transmittance is for electromagnetic radiation having wavelengths in the visible spectrum. In yet another embodiment, the change in transmittance is for electromagnetic radiation having wavelengths in the infrared and visible regions.

[0064] The electrochromic device is reversibly cycled between a bleached state and a colored state. In the bleached state, an electrical potential is applied to electrochromic stack 17 such that the available ions in the stack are primarily at the opposite polarity, which can cause electrochromic materials 11 and 12 to enter the colored state. When the electrical potential across the electrochromic stack is reversed, ions are transported across ion conductor layer 10 and through electrochromic layer 12 to electrochromic material 11, placing the material in the colored state.

[0065] All of the materials comprising the electrochromic stack 17 may be inorganic, solid (i.e., solid-state), or both inorganic and solid. Because organic materials tend to degrade over time, inorganic materials offer the advantage of a reliable electrochromic stack that can function for extended periods of time. Solid materials also have the advantage of eliminating the containment and leakage issues that liquid-state materials often pose. Each layer of the electrochromic device is described in detail below. While any one or more of the layers within the stack may contain some amount of organic material, it should be understood that in many embodiments, one or more layers contain little or no organic material. The same is true for liquids that may be present in small amounts in one or more layers. It should also be understood that solid-state materials may be deposited or otherwise formed by processes employing liquid components, such as certain processes employing sol-gel processes or chemical vapor deposition.

[0066] Any material having suitable optical, electrical, thermal, and mechanical properties may be used as substrates 15 and 16. Such substrates include, for example, glass, plastic, and mirror materials. Suitable plastic substrates include, for example, acrylic, polystyrene, polycarbonate, allyl diglycol carbonate, SAN (styrene acrylonitrile copolymer), poly(4-methyl-1-pentene), polyester, polyamide, and the like. If a plastic substrate is used, it is preferably barrier- and abrasion-protected using, for example, a diamond-like protective coating, a silica / silicone abrasion-resistant coating, or similar hard coat, such as those well known in the plastic glazing art. Suitable glass includes either clear or tinted soda-lime glass, such as soda-lime float glass. The glass may be tempered or untempered.

[0067] Conductive layers 13 and 14 are disposed on substrates 15 and 16. In the present invention, both conductive layers 13 and 14 are inorganic and solid. Conductive layers 13 and 14 may be made from a number of different materials, including conductive oxides, thin metal coatings, and conductive metal nitrides. Typically, conductive layers 13 and 14 are transparent, at least in the wavelength range over which the electrochromic layers exhibit electrochromism. Transparent conductive oxides include metal oxides and metal oxides doped with one or more metals. Examples of such metal oxides and doped metal oxides include indium oxide, indium tin oxide, doped indium oxide, tin oxide, doped tin oxide, zinc oxide, aluminum zinc oxide, doped zinc oxide, ruthenium oxide, doped ruthenium oxide, and the like. Because oxides are often used in these layers, they are sometimes referred to as "transparent conductive oxide" (TCO) layers. Substantially transparent thin metal coatings may also be used. Examples of metals used in such thin metal coatings include transition metals such as gold, platinum, silver, aluminum, nickel alloys, and the like. Silver-based thin metal coatings, well known in the glazing industry, are also used. Examples of conductive nitrides include titanium nitride, tantalum nitride, titanium oxynitride, and tantalum oxynitride. Conductive layers 13 and 14 may also be composite conductors. Such composite conductors may be fabricated by depositing highly conductive ceramic and metal wires or conductive layer patterns on one side of a substrate and then overcoating them with a transparent conductive material such as doped tin oxide or indium tin oxide. Ideally, such wires are thin enough (e.g., about 100 μm or thinner) to be invisible to the naked eye.

[0068] The overlapping conductive layer 13 is the electrochromic layer. In the present invention, dual electrochromic layers 11 and 12 are deposited sequentially. Generally, the electrochromic layer can be inorganic, organic, hybrid, or solid, or in typical embodiments, inorganic / organic / hybrid and solid. The electrochromic layer may contain any one or more of several different electrochromic materials, such as metal oxides. Such metal oxides include tungsten oxide (WO), molybdenum oxide (MoO), niobium oxide (NbO), titanium oxide (TiO), copper oxide (CuO), iridium oxide (IrO), chromium oxide (CrO), manganese oxide (MnO), vanadium oxide (VO), nickel oxide (NiO), cobalt oxide (CoO), and the like. Among metal oxides, tungsten oxide (WO) is the most widely studied material. Metal oxides may also be doped with one or more dopants, such as lithium, sodium, potassium, molybdenum, vanadium, titanium, and / or other suitable metals or metal-containing compounds. Mixed oxides (e.g., W-Mo oxide, WV oxide) can also be used as electrochromic layers. In the case of organic materials, viologens have been put to practical use on a small scale. Viologens have the general formula (C5H4NR)2 n+ WO3 is an organic compound. Various conductive polymers, such as polypyrrole, PEDOT, and polyaniline, are also attracting attention. In the present invention, different forms of WO3 with different crystallinity are used for the electrochromic layers 11 and 12.

[0069] The method for fabricating the EC device is described below.

[0070] First, a glass substrate 15 coated with a transparent conductive oxide 13 is thoroughly cleaned to prepare it for subsequent processing. The cleaning method employed is ultrasonic conditioning of the substrate, which removes unwanted particulates. The electrochromic layers 11 and 12 are then deposited on the conductive layer 13. Generally, the layers may be deposited by a variety of techniques, including physical vapor deposition, chemical vapor deposition, plasma-assisted chemical vapor deposition, and atomic layer deposition, to name a few. The term physical vapor deposition, as used herein, includes all types of PVD techniques, including sputtering, evaporation, ablation, and the like. Subsequently, a free-standing ion-conducting layer 10 is placed on the electrochromic layer, followed by another glass substrate 16 coated with a transparent conductive oxide 14.

[0071] Electrochromic device 1 was prepared by depositing an electrochromic layer 11 made of polycrystalline WO3·H2O nanosheets onto a conductive layer 13. In another embodiment of the present invention, electrochromic device 2 was prepared by depositing an electrochromic layer 12 made of porous a-WO3 onto a conductive layer 13. Optical modulation in the range of 300-1600 nm was recorded for both device configurations.

[0072] A dual-layer electrochromic device 3 was fabricated by sequentially depositing electrochromic layers 11 and 12 on a conductive layer 13. We observed excellent optical modulation and band selectivity in the dual-layer electrochromic device and established dynamic band selectivity with voltage. [Example]

[0073] The following examples are given by way of illustration and therefore should not be construed as limiting the scope of the invention.

[0074] Example 1 Preparation of an active electrode made of polycrystalline WO3·H2O nanosheets An electrochromic layer consisting of polycrystalline WO3·H2O nanosheets was prepared as follows. WO3·H2O powder was synthesized by reacting W powder with H2O2 overnight. First, 5 g of W powder was dissolved in 60 ml of H2O2 (50%) in an ice bath with constant stirring for 24 hours. The solution was then filtered, yielding a clear, colorless liquid. The solution was stirred at 80 °C for 4 hours to decompose excess hydrogen peroxide, changing the solution color to deep yellow, and then the container was capped and left to stand for 1 week. The solution was subsequently dried to produce yellow-colored hydrogen tungstate hydrate (WO3·H2O) powder. In the second step, 0.5 g of WO3·H2O powder was dispersed in 10 ml of distilled water by sonication for 7 hours.

[0075] The active electrode was prepared by drop-casting 20 μL of the electrochromic solution onto a clean FTO substrate (dimensions 1 cm × 1 cm) and subsequently evaporating it at 50 °C for 15 min to form a uniform film. The thickness of the electrochromic layer is 800 nm.

[0076] Example 2 Preparation of an active electrode consisting of a porous a-WO3 layer An electrochromic layer consisting of a porous a-WO3 layer was prepared as follows. WO3·H2O powder was synthesized by reacting W powder with H2O2 overnight. First, 5 g of W powder was dissolved in 60 ml of H2O2 (50%) in an ice bath with constant stirring for 24 hours. The solution was then filtered, yielding a colorless, transparent liquid. The solution was stirred at 80 °C for 4 hours to decompose excess hydrogen peroxide, changing the solution color to deep yellow, and then the container was capped and left to stand for 1 week. The solution was subsequently dried to produce yellow-colored hydrogen tungstate hydrate (WO3·H2O) powder. In the second step, 0.5 g of WO3·H2O powder was dissolved in 10 mL of 10% H2O2 by sonication for 7 hours.

[0077] The active electrode was prepared by drop-casting 20 μL of the electrochromic solution onto a clean FTO substrate (dimensions 1 cm × 1 cm) and subsequently evaporating it at 50 °C for 15 min to form a uniform film. The thickness of the electrochromic layer is 600 nm.

[0078] Example 3 Preparation of electrochromic bilayers consisting of polycrystalline WO3·H2O nanosheets and porous a-WO3 layers An active electrode was prepared by drop-casting 20 μL of the first solution mentioned in Example 1 onto a clean FTO substrate (dimensions 1 cm × 1 cm), which was then evaporated at 50° C. for 15 minutes to form a uniform film, and then drop-casting 20 μL of the second solution mentioned in Example 2 onto the first solution, which was again evaporated at 50° C. for 15 minutes to form a uniform film. The measured thickness of the first layer for this configuration was 880 nm, and the thickness of the second layer was 750 nm.

[0079] Example 4 Preparation of solid polymer electrolyte LiClO4 was dried overnight at 110 °C in a vacuum oven. Measured amounts of salt, PC (plasticizer), and PMMA (host, dried at 90 °C for 12 h) were dissolved in THF and stirred at room temperature for 24 h. The mixture was then poured into a clean Petri dish and covered with aluminum foil with small holes. The solvent was slowly evaporated at room temperature under a stream of dry nitrogen. After 24 h, a free-standing electrolyte membrane (130–250 μm thick) could be peeled off from the Petri dish.

[0080] Example 5 Preparation of the electrochromic device An electrochromic device using polycrystalline WO3·H2O nanosheets was fabricated as follows: a solid polymer electrolyte was sandwiched between the active electrode prepared as mentioned in Example 1 and a second FTO glass. Figures 9 and 10 show the electrochromic properties of the device fabricated using polycrystalline WO3·H2O nanosheets.

[0081] An electrochromic device using a porous a-WO3 layer is fabricated as follows: a solid polymer electrolyte is sandwiched between the active electrode prepared as mentioned in Example 2 and a second FTO glass. Figures 11 and 12 show the electrochromic properties of the device fabricated using a porous a-WO3 layer.

[0082] An electrochromic bilayer device using polycrystalline WO3·H2O nanosheets and a porous a-WO3 layer is fabricated as follows: a solid polymer electrolyte is sandwiched between the active electrode prepared as mentioned in Example 3 and a second FTO glass. Figures 13 and 14 show the electrochromic properties of the bilayer device fabricated using polycrystalline WO3·H2O nanosheets and a porous a-WO3 layer.

[0083] Example 6 Testing the electrochromic activity of the device ECDs using polycrystalline WO3·H2O nanosheets were fabricated as detailed in Example 5, and their modulation in the range of 300–1600 nm was recorded. The fabricated devices turned dark blue upon application of −2.8 V and returned to the bleached state at a similar reverse voltage. These devices exhibited good visible contrast (49% at 650 nm) and excellent NIR (800–1600 nm) blocking (66% at 1500 nm). The average coloration efficiency of the devices was 39.4 cm at 650 nm. 2 C -1 , 103.2 cm at 1500 nm 2 C -1 It was.

[0084] ECDs using porous a-WO layers were fabricated as detailed in Example 5, and their modulation was recorded in the range of 300–1600 nm. The fabricated devices turned dark blue upon application of −2.5 V and returned to the bleached state at a similar reverse voltage. These devices exhibited excellent visible contrast (68% at 650 nm) and moderate near-infrared blocking (40% at 1500 nm). The average coloration efficiency of the devices was 119.3 cm at 650 nm. 2 C -1 , 60.8 cm at 1500 nm 2 C-1 It was.

[0085] An electrochromic bilayer device using polycrystalline WO3·H2O nanosheets and a porous a-WO3 layer was fabricated as described in Example 5. The electrochromic material used in this study was a cathodically coloring material, and the active electrode was connected to the negative terminal of a source meter. We obtained contrasts of 79–91% in the NIR (780–1600 nm) range. The device exhibited NIR modulation of up to ∼71% at potentials up to −2.2 V while remaining inactive in the visible range. Above this point, it began to exhibit activity in the visible range. The highest NIR blocking (91%) was achieved at −2.3 V, although this compromised transmission by ∼9% at 600 nm. Operation of this device between 0 V and −2.3 V is defined as the cool mode. However, the visible light transmittance of the device (300–780 nm) continued to decrease as the voltage increased above −2.3 V. At 2.6 V, the device exhibited 52–79% visual modulation between the bleached and colored states (530–780 nm), which we refer to as the dark mode. The overall device behavior is fully reversible at similar reverse voltages.

[0086] Advantages of the invention • The ECD fabricated using a given bilayer configuration, consisting of a porous a-WO3 layer stacked on a polycrystalline nanosheet layer of WO3·H2O, achieved excellent visual modulation in the visible range and very good contrast in the NIR range, setting a new comprehensive standard for energy saving through electrochromism.

[0087] • The modulation bandwidth of the ECD can potentially be dynamically selected by selectively adjusting the coloration voltage, allowing it to operate in four main modes: fully transparent (0V), transparent + 71% NIR modulation (-2.2V), 9% visible + 91% NIR modulation (-2.3V), and fully opaque (-2.8V).

[0088] ● This inexpensive and extremely high performance fabrication scheme for dynamic ECDs is a major step forward for a new generation of multifunctional dynamic glass.

[0089] • The process of the present invention will produce dynamic windows that will bring high efficiency energy savings in the building / automotive sector.

[0090] • The process developed is economical and commercially feasible. Therefore, by utilizing this method, electrochromic devices can be prepared for smart energy utilization and smart energy saving.

Claims

1. i. a conductive substrate consisting of a substrate [15] coated with a transparent conductive oxide [TCO] [13]; ii. a first electrochromic layer [11] coated on the conductive substrate; iii. A second electrochromic layer [12] deposited on the electrochromic layer [11]; 1. A double layer electrochromic electrode comprising: The thickness of the first electrochromic layer [11] is between 10.0 nm and 3.0 μm, and the thickness of the second electrochromic layer [12] is between 10.0 nm and 3.0 μm; The transparent conductive oxide [TCO] is selected from the group consisting of indium zinc oxide (IZO), fluorine-doped tin oxide (FTO), fluorine-doped zinc oxide (FZO), aluminum-doped zinc oxide (AZO), and aluminum-doped tin oxide (ATO), the first electrochromic layer [11] is polycrystalline WO 3 ·H 2 O nanosheets, and the second electrochromic layer [12] is porous a-WO ３ layer, a double-layer electrochromic electrode.

2. 10. The dual-layer electrochromic electrode of claim 1, wherein the substrate is selected from the group consisting of glass, quartz, cellulose, silk, and plastics selected from the group consisting of polythene, polyimide, polyacrylate, and polycarbonate.

3. 10. The dual layer electrochromic electrode of claim 1, wherein said conductive substrate has a sheet resistance in the range of 1.0 μΩ / sq to 50.0 Ω / sq.

4. The first and second electrochromic layers [11] and [12] comprise an organic compound selected from viologens, thiophenes, and fluorenes, a metal complex selected from bipyridene complexes and terpyridine complexes, a conjugated polymer selected from polythiophenes, polypyrroles, polyanilines, and polycarbazoles, and WO ３ , TiO ２ , MoO ３ , NiO, V ２ O ５ , ZnO, Ta ２ O ５ , Cr ２ O ３ , MnO ２ , Fe ２ O ３ , CoO ２ , RhO ２ , IrO ２ , Nb ２ O ５ 10. The dual layer electrochromic electrode of claim 1, further comprising one or more electrochromic materials selected from metal oxides having pure and sub-stoichiometric phases selected from:

5. a. a double layer electrochromic electrode [active electrode] according to claim 1; b. an electrolyte, i.e., an ion-conducting layer [10] disposed on the second electrochromic layer [12] of the active electrode; c) a counter electrode placed over the exposed side of the electrolyte, comprising a conductive substrate consisting of a transparent conductive oxide [TCO][14] coated transmissive or reflective substrate [16]; 1. A dual layer electrochromic device comprising:

6. 6. The electrochromic device of claim 5, wherein the counter electrode is coated with a complementary coating consisting of a different electrochromic layer with an opposite voltage polarity response to the active electrode.

7. 6. The electrochromic device of claim 5, which exhibits a color change upon application of a voltage in the range of ±0.5 to ±10.0 V relative to a counter electrode.

8. The electrolyte is H ２ SO ４ , or Li ＋ , Na ＋ , K. ＋ , and Al ３＋ 6. The electrochromic device of claim 5, comprising a solution / dispersion / polymer film comprising the salt of the system, or a mixture thereof.

9. 6. The electrochromic device of claim 5, exhibiting overlapping spectral responses resulting from the first electrochromic layer, the second electrochromic layer, and the complementary coating when used with a counter electrode subjected to a voltage ranging from ±0.5 to ±10.0 V relative to the counter electrode.

10. a. Tungsten powder is dissolved in 50% H2O with stirring for a period ranging from 24 to 36 hours. ２ O ２ and then filtering to obtain a clear, colorless liquid; b. Decomposing the excess hydrogen peroxide from the liquid obtained in step (a) by stirring at a temperature ranging from 80 to 90°C for a period ranging from 4 to 6 hours to obtain a deep yellow solution; c. drying the solution obtained in step (b) to obtain a tungsten oxide hydrate powder; d. The tungsten oxide hydrate powder obtained in step (c) is dispersed in water and then subjected to ultrasonic treatment for a period ranging from 7 to 10 hours to obtain tungsten oxide hydrate [WO ３ ・H ２ obtaining a solution of [O]; e. The tungsten oxide hydrate powder obtained in step (c) is dissolved in 10% H ２ O ２ The a-WO was dispersed in an aqueous solution and then subjected to ultrasonic treatment for a period ranging from 7 to 10 hours. ３ obtaining a solution of f. 20-30 μL of the solution obtained in step (d) is drop-cast onto a clean FTO substrate, and then evaporated at a temperature ranging from 50 to 80° C. for a period ranging from 15 to 30 minutes to form a WO film with a thickness ranging from 800 to 1000 nm. ３ ・H ２ obtaining a polycrystalline layer 1 of O; g. 20-30 μL of the solution obtained in step (e) is drop-cast onto the layer obtained in step (f), and then evaporated at a temperature ranging from 50 to 80° C. for a period ranging from 15 to 30 minutes to form a-WO ３ obtaining a porous amorphous layer 2 of h. Polycrystalline WO obtained in step (f) ３ ・H ２ laminating the O nanosheet and the porous a-W03 layer obtained in step (g) to obtain an electrode; 10. A method for making the dual-layer electrochromic electrode of claim 1, comprising:

11. a. Anhydrous LiClO in a solvent selected from the group consisting of tetrahydrofuran, chloroform, DCM, DMSO, DMF, toluene, ethyl acetate, diethyl ether, acetonitrile, carbon tetrachloride, 2-propanol, hexane, benzene, and acetone. ４ , plasticizer, and PMMA are dissolved, and then stirred at a temperature ranging from 60 to 80°C for 12 to 24 hours to obtain a homogeneous mixture; b. Evaporating the solvent under a dry nitrogen stream at a temperature in the range of 80-90°C to obtain a solid polymer electrolyte; c. Polycrystalline WO ３ ・H ２ O nanosheets and porous a-WO ３ and laminating the layers to obtain an active electrode; d. embedding the solid polymer electrolyte obtained in (b) having a thickness ranging from 130 to 250 μm between an active electrode and a reflective electrode to obtain an electrochromic device; 6. A method of making the electrochromic device of claim 5, comprising:

12. The plasticizer may be propylene carbonate, 4-(hydroxymethyl)-1,3-dioxolane-2-one, carbonic acid dibutyl ester, 1-(3-hydroxypropyl)-2-pyrrolidone, 1-octyl-1-2-pyrrolidone; 5-dodecanolide, 1-hexyl-3-methylimidazolium chloride, 1-methyl-3-octylimidizolium chloride, 2,2-dimethyl-1,3-hexanediol; 2-methyl-1,3-pentanediol; 1-cyclohexyl-2-methyl-1,3-pentanediol; 2,4-diethyl-1,5-pentanediol; 1,3-nonanediol; 2-butyl-1,3-octanediol; 3-methylpentane-1,3,5-triol; 2-ethyl-1,3-hexanediol; benzyl alcohol; 3-methyl-1,5-pentanediol; 1-phenoxy-2-propanol; 2-(2-butoxyethoxy)ethanol; 12. The method of claim 11, wherein the alkyl groups are independently selected from the group consisting of bis(2-ethylhexyl) phosphate; tributyl phosphate; tris(2-ethylhexyl) phosphate; linear carbonates; cyclic carbonates; linear primary alcohols; linear and branched aliphatic diols, linear and branched aliphatic triols; benzyl alcohol; linear and cyclic ureas; linear or cyclic urethanes; thioureas; thiourethanes; linear thio-oxocarbonates; pyrrolidon-2-ones; dihydrofuran-2-ones; piperidin-2-ones, and pyran-2-ones.

13. 10. The dual layer device of claim 5, useful in smart windows, smart mirrors, e-paper, smart displays, helmet visors, smart eyeglasses, optical data storage, glare reduction device configurations, thermal and optical transmission modulators, and integrated charge storage devices.

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