Electrochromic device and method of manufacturing the same

Abstract

The present invention relates to an electrochromic device and a method for manufacturing the same. The electrochromic device according to the present invention exhibits excellent transmittance modulation and electrochromic efficiency during initial operation, and even after long-term cycles, structural changes are prevented and secondary phase formation is suppressed, thereby maximizing lifespan, reliability, long-term stability, and durability. Furthermore, the method for manufacturing the electrochromic device according to the present invention enables the production of an electrochromic device with significantly improved long-term stability compared to conventional devices through a relatively simple process.

Description

Technology Field

[0001] The present invention relates to an electrochromic device and a method for manufacturing the same, and more specifically, to an electrochromic device with maximized lifespan, reliability, long-term stability, and durability, and a method for manufacturing the same. Background Technology

[0003] The combustion of fossil fuels for summer cooling and winter heating of buildings is one of the major causes of global warming and climate change, posing a serious threat to the environment and human society. Accordingly, various technological efforts to improve energy efficiency are being pursued in parallel with the development of alternative energy sources such as solar, nuclear, hydrogen, wind, and wave power.

[0004] The building sector accounts for approximately 30 to 40 percent of total energy consumption, and it is reported that more than 40 percent of this heat loss occurs through windows. Against this backdrop, smart windows are attracting attention as a promising solution that can effectively reduce energy loss in buildings.

[0006] Electrochromic devices are particularly suitable materials for smart window applications in buildings because they can control light transmittance with low voltage. When voltage is applied, ions are inserted into or extracted from the electrochromic material, causing a reversible change in transmittance. Under conditions of strong solar radiation, transmittance decreases, which can reduce cooling loads, while in low-illumination environments, transmittance increases, which can reduce energy consumption required for heating.

[0007] Electrochromic materials are being developed based on organic and inorganic sources, each possessing its own advantages and disadvantages. Organic electrochromic materials offer advantages such as the ability to realize various colors and flexibility, but they have limitations in terms of low long-term stability in high-temperature and high-humidity environments. On the other hand, inorganic materials such as WO3, V2O5, Nb2O5, NiO, TiO2, and MoO3 are widely utilized as electrochromic materials for reduction or oxidation electrodes due to their high stability.

[0009] However, despite the high stability of electrochromic inorganic materials such as WO3, for actual device applications, long-term stability in electrolyte environments containing lithium ions or protons and chemical durability under high temperature and high humidity conditions must be additionally ensured, and excellent transmittance modulation characteristics and electrochromic efficiency must also be possessed. Prior art literature

[0011] Republic of Korea Registered Patent Publication No. 10-2397860 The problem to be solved

[0012] The present invention is designed to solve the aforementioned problems and aims to provide an electrochromic device that exhibits excellent transmittance modulation and electrochromic efficiency during initial operation, prevents structural changes even after long-term cycles, and suppresses secondary phase formation, thereby maximizing lifespan, reliability, stability, and durability.

[0013] In addition, another objective of the present invention is to provide a window and a display panel having excellent electrochromic performance, while maximizing the lifespan and long-term stability of the electrochromic function.

[0014] In addition, another objective of the present invention is to provide a method for manufacturing an electrochromic device that can produce an electrochromic device with significantly improved long-term stability and other properties compared to conventional devices through a relatively simple process.

[0016] The problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art to which the present invention belongs from the description below. means of solving the problem

[0018] To solve the above-mentioned problem, an electrochromic element is provided comprising: an electrochromic layer provided on a first electrode; a passivation layer provided on the electrochromic layer; a liquid electrolyte provided on the passivation layer; and a second electrode provided on the liquid electrolyte.

[0019] In addition, the first electrode and / or the second electrode may be a transparent electrode.

[0020] In addition, the electrochromic layer may include WO3.

[0021] In addition, WO3 included in the electrochromic layer is amorphous, and WO3 crystal peaks may not be observed in the XRD graph after 1,000 cycles of the electrochromic layer.

[0022] In addition, the electrochromic layer may have a thickness of 100 to 1000 nm.

[0023] In addition, the passivation layer may include Ta2O5.

[0024] In addition, the passivation layer may have a thickness of 20 to 150 nm.

[0025] In addition, the electrolyte may contain lithium.

[0026] In addition, the above electrochromic device can increase the transmittance modulation rate up to 2000 cycles under conditions of a temperature of 25 ℃ and a voltage range of -1.2 to 0 V.

[0027] In addition, the electrochromic device may have a transmittance modulation of 60% or more at a wavelength of 630 nm after 8,000 cycles under conditions of a temperature of 25 ℃ and a voltage range of -1.2 to 0 V.

[0028] In addition, the electrochromic device has a current density of -1.5 A / cm² at -1.20 V after 200 cycles under conditions of a temperature of 50 ℃ and a voltage range of -1.2 to 0 V. 2It may be less than.

[0030] To solve the above-described problem, a window including the above-described electrochromic element or a display panel including the above-described electrochromic element is provided.

[0032] To solve the above-mentioned problem, a method for manufacturing an electrochromic device is provided, comprising: (1) forming an electrochromic layer on a first electrode; (2) forming a passivation layer on the electrochromic layer; (3) positioning the passivation layer and a second electrode opposite each other; and (4) supplying a liquid electrolyte between the passivation layer and the second electrode.

[0033] In addition, in step (2) above, the passivation layer can be formed to a thickness of 20 to 150 nm.

[0035] To solve the above-described problem, an electrochromic device manufactured by the above-described manufacturing method is provided. Effects of the invention

[0037] The electrochromic device according to the present invention exhibits excellent transmittance modulation and electrochromic efficiency during initial operation, and even after long-term cycles, structural changes are prevented and secondary phase formation is suppressed, thereby maximizing lifespan, reliability, long-term stability, and durability.

[0038] In addition, the window and display panel according to the present invention have excellent electrochromic performance, and the lifespan and long-term stability of the electrochromic function are maximized.

[0039] Furthermore, the method for manufacturing an electrochromic device according to the present invention can manufacture an electrochromic device with significantly improved long-term stability and other properties compared to conventional devices through a relatively simple process.

[0041] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the composition of the invention described in the description or claims of the present invention. Brief explanation of the drawing

[0043] FIG. 1 is a schematic cross-sectional view of an electrochromic element according to a preferred embodiment of the present invention. Figure 2 is a Scanning Electron Microscope (SEM) image of the surface (Top-view) of a 300 nm WO3 electrochromic layer formed on a Si substrate. Figure 3 is an SEM image of the surface of a 100 nm Ta2O5 passivation layer formed on a Si substrate. Figure 4 is an SEM image of the surface of a 50 nm Ta2O5 passivation layer provided on a WO3 electrochromic layer (300 nm). Figure 5 is an SEM image of the surface of a 100 nm Ta2O5 passivation layer provided on a WO3 electrochromic layer (300 nm). Figure 6 shows surface SEM and cross-sectional SEM images of a WO3 electrochromic layer (300 nm) without a passivation layer after 1000 cycles of operation at 25 ℃. Figure 7 shows surface SEM and cross-sectional SEM images of a 50 nm Ta2O5 passivation layer provided on a WO3 electrochromic layer (300 nm) after 1000 cycles of operation under 25 ℃ conditions. Figure 8 is an XRD (X-ray Diffraction) graph of a 300 nm WO3 electrochromic layer formed on a Si substrate. Figure 9 is an XRD graph of a 100 nm Ta2O5 passivation layer formed on a Si substrate. Figure 10 is an XRD graph of a WO3 electrochromic layer (300 nm) without a passivation layer and a WO3 electrochromic layer (300 nm) with a Ta2O5 passivation layer 50 nm on top, after 1000 cycles of operation under 25 ℃ conditions. Figure 11 shows the cyclic voltammetry (CV) results under 25°C conditions for a WO3 electrochromic layer (300 nm) without a passivation layer and a WO3 electrochromic layer (300 nm) with Ta2O5 passivation layers (25, 50, 100, 200 nm) provided on top. Figure 12 shows the CV results under 25°C conditions for an electrochromic device without a passivation layer and an electrochromic device including a 50 nm Ta2O5 passivation layer. Figure 13 shows the CV results according to the number of cycles when an electrochromic device without a passivation layer is operated at 50°C. Figure 14 shows the CV results according to the number of cycles when an electrochromic device including a 50 nm Ta2O5 passivation layer is operated at 50 ℃. Figure 15 shows the coloration and decolorization transmittance results according to wavelength of a WO3 electrochromic layer (300 nm) without a passivation layer. Figure 16 shows the coloration and decolorization transmittance results according to wavelength of a WO3 electrochromic layer (300 nm) with a Ta2O5 passivation layer (25 nm) on top. Figure 17 shows the coloration and decolorization transmittance results according to wavelength of a WO3 electrochromic layer (300 nm) with a Ta2O5 passivation layer of 50 nm on top. Figure 18 shows the coloration and decolorization transmittance results according to wavelength of a WO3 electrochromic layer (300 nm) with a Ta2O5 passivation layer of 100 nm on top. Figure 19 shows the coloration and decolorization transmittance results according to wavelength of a WO3 electrochromic layer (300 nm) with a Ta2O5 passivation layer (200 nm) on top. FIG. 20 is a graph of the change in optical density (ΔOD) according to charge density for a WO3 electrochromic layer (300 nm) without a passivation layer and a WO3 electrochromic layer (300 nm) with a Ta2O5 passivation layer of 50 nm or 100 nm on top, showing the color change efficiency. Figure 21 shows the in-situ transmittance results according to the number of cycles of a WO3 electrochromic layer (300 nm) without a Ta2O5 passivation layer. Figure 22 shows the in-situ transmittance results according to the number of cycles of a WO3 electrochromic layer (300 nm) with a Ta2O5 passivation layer of 50 nm on top. Figure 23 shows the coloration and decolorization transmittance results according to wavelength of an electrochromic device without a passivation layer. Figure 24 shows the coloration and decolorization transmittance results according to wavelength of an electrochromic device containing a Ta2O5 passivation layer of 50 nm. Figure 25 shows the change in optical density (ΔOD) according to charge density for an electrochromic device without a passivation layer and an electrochromic device including a Ta2O5 passivation layer of 50 nm, and indicates the color change efficiency. Figure 26 shows the in-situ transmittance results according to the number of cycles for an electrochromic device containing a Ta2O5 passivation layer of 50 nm. Figure 27 is an SEM image of the surface of a WO3 electrochromic layer (300 nm) without a passivation layer after immersion in hot water at 70°C for 30 seconds. Figure 28 is an SEM image of the surface of a WO3 electrochromic layer (300 nm) without a passivation layer after immersion in hot water for 120 seconds. FIG. 29 is an SEM image of the surface of a WO3 electrochromic layer (300 nm) with a Ta2O5 passivation layer of 50 nm on top after immersion in hot water for 150 seconds. FIG. 30 is an SEM image of the surface of a WO3 electrochromic layer (300 nm) with a Ta2O5 passivation layer of 50 nm on top after immersion in hot water for 600 seconds. Figure 31 is an SEM image of the surface of a WO3 electrochromic layer (300 nm) with a Ta2O5 passivation layer of 100 nm on top after immersion in hot water for 150 seconds. FIG. 32 is an SEM image of the surface of a WO3 electrochromic layer (300 nm) with a Ta2O5 passivation layer of 100 nm on top after immersion in hot water for 600 seconds. FIG. 33 is the CV result of a WO3 electrochromic layer (300 nm) without a passivation layer and a WO3 electrochromic layer (300 nm) with a Ta2O5 passivation layer 50 nm on top, after immersion in hot water for 150 seconds. Specific details for implementing the invention

[0044] Hereinafter, the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement it. The present invention may be embodied in various forms and is not limited to the embodiments described herein. In the drawings, parts not directly related to the description have been omitted to clearly explain the present invention, and the same reference numerals are assigned to identical or similar components throughout the specification.

[0045] The terms used in this specification are used merely to describe specific embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, terms such as “comprising” or “having” should be understood as indicating the presence of the features, numbers, steps, actions, components, or combinations thereof described in the specification, and not as precluding the possibility that one or more other features, numbers, steps, actions, components, or combinations thereof may be present or added.

[0046] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms identical to those defined in commonly used dictionaries should be interpreted in a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined herein.

[0047] When a part such as a layer, membrane, region, or plate is said to be "above" another part, this includes not only the case where it is "directly above" the other part, but also the case where there is another part in between. Conversely, when a part is said to be "directly above" another part, it means that there is no other part in between.

[0049] As mentioned above, despite the high stability of electrochromic inorganic materials such as WO3, for actual device applications, long-term stability in electrolyte environments containing lithium ions or protons and chemical durability under high temperature and high humidity conditions must be additionally ensured, and excellent transmittance modulation characteristics and electrochromic efficiency must also be possessed.

[0051] Accordingly, the present invention seeks to solve the above-described problem by providing an electrochromic element (100) comprising: an electrochromic layer (120) provided on a first electrode (110); a passivation layer (130) provided on the electrochromic layer (120); a liquid electrolyte (140) provided on the passivation layer (130); and a second electrode (150) provided on the liquid electrolyte (140).

[0052] Such electrochromic devices exhibit excellent transmittance modulation and electrochromic efficiency during initial operation, and even after long-term cycles, structural changes are prevented and secondary phase formation is suppressed, thereby maximizing lifespan, reliability, long-term stability, and durability.

[0053] Hereinafter, the electrochromic element of the present invention will be described in detail with reference to FIG. 1.

[0055] The electrochromic element (100) according to the present invention includes a first electrode (110) and a second electrode (150).

[0056] Since the first electrode and / or second electrode are electrodes used in an electrochromic device, it is preferable that they be transparent electrodes. In this case, a transparent electrode means having an average transmittance of 60% or more in the visible light region (400 to 700 nm).

[0057] The transparent electrode may include, but is not limited to, ITO (Indium Tin Oxide), FTO (Fluorine-doped Tin Oxide), ATO (Sb2O3-doped Tin Oxide), GTO (Gallium-doped Tin Oxide), ZTO (tin-doped zinc oxide), ZTO:Ga (gallium-doped ZTO), IGZO (Indium-gallium-zinc oxide), IZO (Indium-doped zinc oxide), or AZO (Aluminum-doped zinc oxide). Preferably, the transparent electrode may be an ITO-based electrode.

[0058] The first electrode or the second electrode may each have a thickness of 50 to 500 nm, but is not limited thereto and may be any thickness that can be generally used in an electrochromic device.

[0060] The following describes the electrochromic layer (120) of the present invention.

[0061] The above electrochromic layer is a layer that performs the core function of an electrochromic device and is capable of reversibly changing transmittance, reflectance, absorbance, etc., depending on an external voltage.

[0062] The electrochromic layer may include one or more selected from the group consisting of WO3, V2O5, Nb2O5, NiO, TiO2, and MoO3. Preferably, the electrochromic layer may include WO3. If the electrochromic layer includes WO3, the transmittance modulation characteristics, response speed, and electrochromic efficiency of the electrochromic device may be excellent.

[0063] Referring to FIGS. 8 and FIGS. 10, when the electrochromic layer contains WO3, the WO3 may be amorphous, and the WO3 crystal peak may not be observed in the XRD graph after 1,000 cycles of the electrochromic layer. Even after long-term operation, WO3 does not crystallize in the electrochromic layer containing WO3, so no structural change occurs on the surface of the electrochromic layer, and accordingly, long-term stability can be achieved.

[0064] The thickness of the electrochromic layer may be 100 to 1000 nm, and preferably 200 to 500 nm. If the thickness of the electrochromic layer is less than 100 nm, the volume of the electrochromic layer into which ions present in the electrolyte can be inserted is excessively small, which may result in reduced transmittance modulation and coloring efficiency (color change efficiency), and may result in insufficient durability due to the thin thickness. On the other hand, if it exceeds 1000 nm, the travel distance of ions and electrons increases, which may result in a slower switching speed, and the electrical resistance increases, which may result in lower power efficiency.

[0066] The electrochromic element (100) according to the present invention includes a passivation layer (130).

[0067] Referring to FIGS. 6, 7, 13, 14, and FIGS. 21 through 33, the passivation layer functions as a barrier between the electrochromic layer and the liquid electrolyte, thereby preventing surface degradation due to crystallization of the electrochromic layer even after long-term operation and maintaining the surface shape of the electrochromic layer. Consequently, the passivation layer can improve the transmittance modulation rate, transmittance in the decolorized state, long-term stability, lifespan, durability, and reliability of the electrochromic device, and can provide long-term stability even in high temperature and high humidity environments. In particular, crystallization of the electrochromic layer is very detrimental to the performance of the electrochromic device, because crystallization of the electrochromic layer increases the risk of short circuits in the device, causes an unstable form, and leads to loss of the electrochromic material of the electrochromic layer.

[0068] The above passivation layer may include Ta2O5. Such a passivation layer including Ta2O5 can improve the long-term stability, lifespan, and reliability of the electrochromic device, while also providing excellent electrochromic performance, such as transmittance, transmittance modulation rate, and color change efficiency, compared to an Nb2O5 passivation layer.

[0069] Referring to FIG. 9, if the passivation layer contains Ta2O5, the Ta2O5 included in the passivation layer may be amorphous, but is not limited thereto.

[0070] Referring to FIGS. 11, 15 to 20, the passivation layer may have a thickness of 20 to 150 nm, and, for example, may be a range in which the lower value among two selected values ​​from 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, and 150 nm is set as the lower limit and the higher value is set as the upper limit. Preferably, it may be 35 to 75 nm, and most preferably, it may be 40 to 60 nm.

[0071] If the thickness of the passivation layer is less than 20 nm, it is a transparent insulator containing Ta2O5 with a refractive index (n) of approximately 2.0 to 2.2. In a thin thickness, the interference effect between incident and reflected light may increase, and because the thickness is very thin, there is a high possibility that it will not grow uniformly or that surface roughness or scattering centers exist, the transmittance in the decolorized state may be low, and consequently, the transmittance modulation rate may be low. In addition, because the passivation layer is thin, its uniformity is not constant, and as some parts of the electrochromic layer are exposed, it may be difficult to prevent crystallization or surface degradation of the electrochromic layer. On the other hand, if the thickness of the passivation layer exceeds 150 nm, the passivation layer excessively restricts ion movement, which may reduce the color-dyeing current density and transmittance modulation rate, and the color change efficiency may decrease at the same charge amount.

[0072] Meanwhile, if the thickness of the passivation layer is 35 to 75 nm, the thickness is appropriate, so the interference effect between incident and reflected light can be reduced, and as the passivation layer grows more uniformly, the likelihood of surface roughness or scattering centers existing is reduced, so the decolorization transmittance can be increased, and the likelihood of the electrochromic layer being exposed is reduced, so crystallization and surface deterioration can be prevented. In addition, since the thickness is appropriate, ion movement can not be restricted, so the coloring / decolorization current density, transmittance modulation rate, and color change efficiency can be excellent.

[0073] If the thickness of the passivation layer is 40 to 60 nm, the long-term stability and lifespan of the electrochromic device are significantly increased, and the electrochromic performance, such as color change efficiency and transmittance modulation rate, can also be excellent.

[0075] Next, the liquid electrolyte (140) included in the electrochromic element will be described.

[0076] Although the above electrolyte is a liquid electrolyte, the electrochromic device of the present invention includes a passivation layer, so the deterioration of the electrochromic layer can be prevented even after long-term operation.

[0077] The above electrolyte may contain lithium. For example, the above electrolyte may contain lithium in the form of LiClO4. When the electrolyte contains lithium, high color change efficiency and reactivity are exhibited, and coloring and decolorization can be controlled in various electrochromic materials, and in particular, the mobility of lithium ions may be excellent when in the form of LiClO4. Preferably, the lithium may be included at a concentration of 0.1 to 10 M.

[0078] Furthermore, there are no restrictions on the solvent of the above-mentioned liquid electrolyte as long as it is one that can be conventionally used in the industry. For example, it may be propylene carbonate. In particular, when using propylene carbonate as a solvent, if a lithium salt is included, propylene carbonate is a non-aqueous solvent that mixes well with the lithium salt to provide a stable electrolyte environment, which can result in excellent discoloration speed and coloring efficiency, and prevent electrolyte decomposition even at high voltages. Additionally, propylene carbonate is non-volatile, does not vaporize, and has excellent thermal stability, making it stable even in high-temperature environments. It also has low reactivity with oxygen, which may result in fewer side reactions. Furthermore, it exhibits minimal side reactions with the electrochromic layer, which can prevent surface degradation of the electrochromic layer.

[0079] The above electrolyte may be provided between the passivation layer and the second electrode, and the gap between the passivation layer and the second electrode is not limited as long as it is conventionally applicable in the industry, but preferably may be 10 to 500 μm. If the gap is less than 10 μm, the gap may be too thin so that the electrolyte is not sufficiently filled and leakage current may occur. If the gap exceeds 500 μm, the reaction speed of coloring and decolorizing of the electrochromic device may slow down, the device driving voltage may increase, and there may be difficulties in miniaturizing the device.

[0081] The above electrochromic element (100) may additionally include a substrate.

[0082] The above substrate may be provided below the first electrode or above the second electrode.

[0083] The above substrate may be used without limitation as long as it is used in an electrochromic device, but preferably it may be a glass substrate.

[0084] The thickness of the substrate is not limited as long as it is a thickness that can be ordinarily applied by a person skilled in the art, so the present invention does not specifically limit it. Preferably, the thickness of the substrate may be 0.1 to 10 mm.

[0086] Referring to FIGS. 15 to 19, the electrochromic layer having a passivation layer in the electrochromic device may have a transmittance modulation of 62% or more at a wavelength of 630 nm in the first cycle, and preferably 68% or more. At this time, the electrolyte is propylene carbonate containing 0.5 M LiClO4.

[0087] In the electrochromic device described above, the electrochromic layer having a passivation layer may have a coloration efficiency (η) of 48% or more in the first cycle when the electrolyte is propylene carbonate containing 0.5 M LiClO4 (Fig. 20). Alternatively, the electrochromic device may have a coloration efficiency of 40% or more in the first cycle when the electrolyte is propylene carbonate containing 0.5 M LiClO4 and 0.05 M ferrocene (Fig. 25). Meanwhile, when the thickness of the passivation layer of the present invention is 35 to 75 nm, the above-described coloration efficiency is highly likely to be exhibited.

[0089] Referring to FIGS. 21 and 22, the electrochromic layer having a passivation layer in the electrochromic device may have a transmittance modulation of 30% or more at a wavelength of 630 nm after 1000 cycles under conditions of a temperature of 25 ℃ and a voltage range of -1.0 to 1.0 V. At this time, the electrolyte is propylene carbonate containing 0.5 M LiClO4.

[0090] As shown in FIG. 26, the electrochromic device can increase the transmittance modulation rate up to 2000 cycles under conditions of a temperature of 25 ℃ and a voltage range of -1.2 to 0 V. At this time, the electrolyte is propylene carbonate containing 0.5 M LiClO4 and 0.05 M ferrocene.

[0091] The electrochromic device described above can have a transmittance modulation of 60% or more at a wavelength of 630 nm after 8,000 cycles under conditions of a temperature of 25 ℃ and a voltage range of -1.2 to 0 V (Fig. 26). At this time, the electrolyte is propylene carbonate containing 0.5 M LiClO4 and 0.05 M ferrocene.

[0092] Referring to FIGS. 13 and 14, the electrochromic element has a current density of -1.5 A / cm² at -1.20 V after 200 cycles under conditions of a temperature of 50 °C and a voltage range of -1.2 to 0 V. 2 It may be less than or equal to 0. In this case, the electrolyte is propylene carbonate containing 0.5 M LiClO4 and 0.05 M ferrocene.

[0094] To solve the above problem, a window or display panel including the above-described electrochromic element (100) is provided.

[0095] Since the window and display panel of the present invention include an electrochromic element according to the present invention, excellent electrochromic performance can be achieved, and the lifespan and long-term stability of the electrochromic function can be maximized.

[0097] To solve the above-mentioned problem, a method for manufacturing an electrochromic element (100) is provided, comprising: (1) forming an electrochromic layer (120) on a first electrode (110); (2) forming a passivation layer (130) on the electrochromic layer (120); (3) positioning the passivation layer (130) and a second electrode (150) opposite each other; and (4) supplying a liquid electrolyte (140) between the passivation layer (130) and the second electrode (150).

[0098] Through this, the aforementioned electrochromic device can be manufactured, and since the process is relatively simple, manufacturing costs can be reduced, and the manufactured electrochromic device can have significantly improved long-term stability compared to conventional devices.

[0100] First, as a step (1), an electrochromic layer (120) is formed on the first electrode (110).

[0101] The first electrode may be provided on a substrate. That is, a substrate may be located below the first electrode.

[0102] Specific details regarding the first electrode, electrochromic layer, and substrate described above that overlap with those described above will be omitted. For example, the first electrode or substrate may each have a thickness of 50 to 500 nm or 0.1 to 10 mm as described above, and the electrochromic layer may be formed with a thickness of 100 to 1000 nm.

[0103] The method for forming the electrochromic layer may be a deposition process and / or a solution process. The deposition process may be any common deposition process used in the industry, such as thermal evaporation, vacuum deposition, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), or air jet processes. Additionally, the solution process may be any common solution process used in the industry, such as spin coating, slot die coating, blade coating, printing coating, inkjet printing, gravure coating, spray coating, or Mayer Rod Coating. Preferably, the electrochromic layer can be formed through a physical vapor deposition (PVD) process, and more preferably, through a sputtering process.

[0104] If the above electrochromic layer is formed through sputtering, the conditions are not specifically limited, and there are no restrictions on any method applicable in the industry to form the above electrochromic layer.

[0106] Next, as step (2), a passivation layer (130) is formed on the electrochromic layer (120) formed in step (1).

[0107] Specific details regarding the passivation layer described above that overlap with those previously described will be omitted. For example, as described above, the passivation layer can be formed to a thickness of 20 to 150 nm, preferably to a thickness of 35 to 75 nm, and most preferably to a thickness of 40 to 60 nm.

[0108] The method for forming the passivation layer may be a deposition process and / or a solution process. The deposition process may be any common deposition process used in the industry, such as thermal evaporation, vacuum deposition, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), or air jet processes. Additionally, the solution process may be any common solution process used in the industry, such as spin coating, slot die coating, blade coating, printing coating, inkjet printing, gravure coating, spray coating, or Mayer Rod Coating. Preferably, the passivation layer can be formed through a physical vapor deposition (PVD) process, and more preferably, through a sputtering process.

[0109] If the above passivation layer is formed through sputtering, the conditions are not specifically limited, and there are no restrictions on any method applicable in the industry to form the passivation layer.

[0111] Next, as step (3), the passivation layer (130) formed in step (2) and the second electrode (150) are brought into contact.

[0112] Specific details regarding the second electrode described above that overlap with those previously described will be omitted. For example, as described above, the second electrode may have a thickness of 50 to 500 nm.

[0113] The above passivation layer and the second electrode may be positioned such that the gap between them is 10 to 500 μm, but is not limited thereto.

[0115] (4) As a step, a liquid electrolyte (140) is supplied between the opposing passivation layer (130) and the second electrode (150) in step (3).

[0116] Specific details regarding the above liquid electrolyte that overlap with those previously described will be omitted. For example, as described above, the above liquid electrolyte may contain lithium.

[0118] The present invention will be explained more specifically through the following examples, but the following examples are not intended to limit the scope of the invention and should be interpreted as being for the purpose of aiding understanding of the invention.

[0120] <Example>

[0121] Example 1

[0122] WO3 (99.9%, Kojundo Chemical Laboratory Co., Ltd., Japan) and Ta2O5 (99.9%, Kojundo Chemical Laboratory Co., Ltd., Japan) powders were ground using a ball mill for 24 hours, dried, and formed into pellets in a 2-inch mold. The WO3 pellets and Ta2O5 pellets were sintered in a box furnace under normal atmosphere at 1150 °C for 3 hours and 1300 °C for 5 hours, respectively, with the heating and cooling rates set to 5 °C / min. Two ITO-coated glass substrates (sheet resistance: 10 Ω / sq) were prepared by ultrasonically cleaning them in acetone, ethanol, and ultrapure water for 10 minutes each.

[0123] A 300 nm WO3 electrochromic layer was deposited on the glass substrate by magnetron sputtering using WO3 pellets under 50 W DC power (SPF-2, SJ Power) and room temperature conditions. Next, a 25 nm Ta2O5 passivation layer was deposited on the electrochromic layer by magnetron sputtering using Ta2O5 pellets under 50 W RF power (YSR-03HDP, YOUNGSI-RF Co., Ltd., Japan) and room temperature conditions. At this time, the chamber used for sputtering the electrochromic layer and the passivation layer was ~10 -6 Basic exhaust was performed down to Torr, and deposition of each layer was carried out at 20 mTorr using a mixed gas with a ratio of Ar:O2 = 10:2.

[0124] The passivation layer was positioned opposite the pre-prepared ITO-coated glass substrate at a distance of 125 μm, and the area of ​​the opposing surface was 2.3 x 1.3 cm 2 This was done. Next, an electrochromic device was manufactured by supplying a liquid electrolyte between the passivation layer and the substrate.

[0126] Example 2

[0127] The product was prepared as shown in Table 1 by carrying out the same procedure as Example 1, except that a 50 nm passivation layer was deposited instead of a 25 nm layer.

[0129] Example 3

[0130] The procedure was carried out in the same manner as Example 1, except that a 100 nm passivation layer was deposited instead of a 25 nm layer, and the product was prepared as shown in Table 1.

[0132] Example 4

[0133] The procedure was carried out in the same manner as Example 1, except that a 200 nm passivation layer was deposited instead of a 25 nm layer, and the product was prepared as shown in Table 1.

[0135] <Comparative Example>

[0136] Comparative Example 1

[0137] Except for not depositing a passivation layer, the same procedure as in Example 1 was carried out to produce the product as shown in Table 1.

[0139] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Passivation layer [nm] 25 50 100 200 -

[0141] <Experimental Example>

[0142] Experimental Example 1: Surface analysis of electrochromic layer and passivation layer

[0143] SEM imaging was performed using a scanning electron microscope (FE-SEM; S-4800, Hitachi, Japan).

[0144] First, a 300 nm WO3 layer was formed on a Si substrate using the same sputtering method used to form the WO3 layer of Example 1, and the WO3 layer was observed using a scanning electron microscope, as shown in Fig. 2. Additionally, a 100 nm Ta2O5 layer was formed on a Si substrate using the same sputtering method used to form the Ta2O5 layer of Example 1, and the Ta2O5 layer was observed, as shown in Fig. 3. Then, a 300 nm WO3 layer and a 50 nm Ta2O5 layer were formed sequentially on a Si substrate using the same sputtering method used to form the WO3 layer and Ta2O5 layer of Example 1, and the Ta2O5 layer was observed, as shown in Fig. 4. Furthermore, a 300 nm WO3 layer and a 100 nm Ta2O5 layer were formed sequentially on a Si substrate using the same sputtering method used to form the WO3 layer and Ta2O5 layer of Example 1, and the Ta2O5 layer was observed, as shown in Fig. 5.

[0145] Meanwhile, regarding the 300 nm WO3 electrochromic layer formed on an ITO-coated glass substrate as described in Comparative Example 1, 0.5 M LiClO4 propylene carbonate electrolyte, ITO-coated glass (working electrode), Pt mesh (counter electrode), Ag / Ag +Using a (reference electrode), after driving for 1,000 cycles at 25°C, the surface and cross-section of the electrochromic layer were observed and are shown in Fig. 6. In addition, regarding the WO3 electrochromic layer of 300 nm formed on an ITO-coated glass substrate and the Ta2O5 passivation layer of 50 nm formed on the electrochromic layer as described in Example 2, 0.5 M LiClO4 propylene carbonate electrolyte, ITO-coated glass (working electrode), Pt mesh (counter electrode), Ag / Ag + Using a (reference electrode), after driving for 1000 cycles at 25°C, the surface and cross-section of the passivation layer were observed and are shown in Fig. 7.

[0147] Referring to Figure 2, a 300 nm thick WO3 layer sputtered on a Si substrate exhibited a dense surface shape composed of irregular clusters (diameter 20 to 40 nm) and had a purple color.

[0148] As shown in Fig. 3, the 100 nm thick Ta2O5 layer sputtered on the Si substrate exhibited a cluster shape smaller than the clusters of the 300 nm thick WO3 layer and was blue.

[0149] Referring to Figures 4 and 5, no significant surface changes were observed on the surface of a 50 nm or 100 nm thick Ta2O5 layer sputtered on a 300 nm thick WO3 layer sputtered on a Si substrate compared to Figure 3. However, only the color changed due to the difference in thickness of the Ta2O5 layer.

[0150] Meanwhile, the surface morphology of the WO3 and Ta2O5 layers deposited on the ITO-coated glass substrate was also nearly identical to that of the thin film on the Si substrate.

[0152] Referring to Fig. 6, the WO3 electrochromic layer of Comparative Example 1, with a diameter of 300 nm, had hexagonal plate-like crystals of 200 to 400 nm formed on its surface at a 120° angle after 1,000 cycles. This was due to the crystallization of the electrochromic material during the insertion and extraction of lithium ions. Such crystallization implies a loss of the electrochromic material in the electrochromic layer and can cause a degradation in performance.

[0153] Meanwhile, referring to Fig. 7, the 50 nm Ta2O5 passivation layer formed on the 300 nm WO3 electrochromic layer of Example 2 maintained a uniform surface shape without forming the aforementioned hexagonal crystals even after 1,000 cycles. Although a small number of bright particles ranging from 10 to 60 nm appeared on the surface, the overall structure (Ta2O5 / WO3 / ITO / glass) was maintained without damage. This is because the crystallization and surface degradation of the electrochromic layer were effectively prevented by the passivation layer.

[0155] Experimental Example 2: XRD (X-ray Diffraction) Analysis

[0156] XRD analysis was performed using an X-ray diffraction instrument (XRD; AERIS 600, Malvern PANalytical, USA).

[0157] A WO3 layer of 300 nm was formed on a Si substrate using the same sputtering method used to form the WO3 layer of Example 1, and the WO3 layer was measured by XRD and is shown in Fig. 8.

[0158] In addition, a 100 nm thick Ta2O5 layer was formed on a Si substrate using the same sputtering method used to form the Ta2O5 layer of Example 1, and the Ta2O5 layer was measured by XRD, as shown in Fig. 9.

[0159] For the 300 nm WO3 electrochromic layer formed on an ITO-coated glass substrate as described in Comparative Example 1, 0.5 M LiClO4 propylene carbonate electrolyte, ITO-coated glass (working electrode), Pt mesh (counter electrode), Ag / Ag + Using a (reference electrode), after driving for 1000 cycles at 25°C, the ITO and WO3 electrochromic layers were XRD measured and represented as WO3 / ITO in Fig. 10.

[0160] In addition, regarding the WO3 electrochromic layer of 300 nm formed on an ITO-coated glass substrate and the Ta2O5 passivation layer of 50 nm formed on the electrochromic layer as described in Example 2, 0.5 M LiClO4 propylene carbonate electrolyte, ITO-coated glass (working electrode), Pt mesh (counter electrode), Ag / Ag + Using a (reference electrode), after driving for 1,000 cycles at 25°C, the ITO, WO3 electrochromic layer, and Ta2O5 passivation layer were XRD measured using the X-ray diffraction apparatus. This is represented as Ta2O5 / WO3 / ITO in Fig. 10.

[0162] Referring to Figures 8 and 9, in this case, only the (002) and (004) diffraction lines of the Si substrate appeared in the XRD of the WO3 layer 300 nm, confirming that the WO3 thin film is amorphous and that the irregular clusters with a diameter of 20 to 40 nm confirmed in Experimental Example 1 are not crystalline grains. Similarly, in the case of the Ta2O5 layer 100 nm, only the (002) and (004) diffraction lines of the Si substrate appeared in the XRD, confirming that the Ta2O5 layer is amorphous.

[0163] In the case where a 300 nm WO3 layer and a 50 nm Ta2O5 layer were formed sequentially on a Si substrate, and in the case where a 300 nm WO3 layer and a 100 nm Ta2O5 layer were formed sequentially on a Si substrate, it was confirmed that the WO3 layer and the Ta2O5 layer still maintained an amorphous state in the XRD pattern. Meanwhile, the WO3 layer and the Ta2O5 layer deposited on an ITO-coated glass substrate were also confirmed to be amorphous as no peaks associated with WO3 and Ta2O5 appeared in the XRD pattern.

[0165] As shown in FIG. 10, after 1000 cycles, peaks corresponding to the (001), (002), and (003) planes of hexagonal WO3 were observed at 14.0°, 28.2°, and 42.8°, respectively, in the WO3 electrochromic layer 300 nm of Comparative Example 1, while peaks corresponding to trigonal Li2WO4 appeared at 17.0°, 21.0°, and 38.2°. In other words, crystallization of the initial amorphous WO3 proceeded during long-term cycling. These WO3 and Li2WO4 crystals can cause an increased risk of short circuits and shape instability in electrochromic devices, and the crystals may delaminate, significantly reducing the stability of the device and significantly decreasing device performance in the long term. On the other hand, after 1000 cycles, only ITO diffraction peaks were observed on XRD for the Ta2O5 passivation layer 50 nm and WO3 electrochromic layer 300 nm of Example 2, which means that Ta2O5 and WO3 remained in an amorphous state, and the passivation layer effectively prevented crystallization and surface degradation of the electrochromic layer.

[0167] Experimental Example 3: CV (Cyclic Voltammetry) Analysis

[0168] CV analysis was performed using an electrochemical measuring instrument (Autolab PGSTAT 302 N, Metrohm, Switzerland).

[0169] First, regarding the 300 nm WO3 electrochromic layer formed on an ITO-coated glass substrate as described in Comparative Example 1, 0.5 M LiClO4 propylene carbonate electrolyte, ITO-coated glass (working electrode), Pt mesh (counter electrode), Ag / Ag + CV analysis was performed at 25 ℃ using a (reference electrode), and this is shown in Fig. 11. At this time, the voltage range was set to -1.0 V to +1.0 V, and the scan speed was set to 50 mV / s.

[0170] In addition, regarding the WO3 electrochromic layer of 300 nm formed on an ITO-coated glass substrate and the Ta2O5 passivation layers of 25, 50, 100, and 200 nm formed on the electrochromic layer, respectively described in Examples 1, 2, 3, and 4, a 0.5 M LiClO4 propylene carbonate electrolyte, ITO-coated glass (working electrode), Pt mesh (counter electrode), and Ag / Ag + CV analysis was performed at 25 ℃ using a (reference electrode), and this is shown in Fig. 11. At this time, the voltage range was set to -1.0 V to +1.0 V, and the scan speed was set to 50 mV / s.

[0171] Meanwhile, propylene carbonate containing 0.5 M LiClO4 and 0.05 M ferrocene was used as the electrolyte for the electrochromic devices of Comparative Example 1 and Example 2. CV analysis was performed on the electrochromic devices of Comparative Example 1 and Example 2 under conditions of 25 ℃ and is shown in Fig. 12. Additionally, the electrochromic devices of Comparative Example 1 and Example 2 were operated under conditions of 50 ℃, and the CV results according to the number of cycles are shown in Figs. 13 and 14, respectively. CV analysis for the electrochromic devices was performed in the voltage range of -1.2 V to 0 V.

[0173] Referring to Fig. 11, distinct oxidation and reduction peaks were observed in the case without a passivation layer, as in Comparative Example 1. Specifically, for the WO3 electrochromic layer of Comparative Example 1, when a negative voltage of -1.0 V was applied, the current density was -1.68 mA / cm² 2 It decreased, and the transparent WO3 electrochromic layer turned dark blue, indicating reduction due to lithium (Li) ion insertion. Conversely, in the voltage increasing range, the current density was 1.11 mA / cm² at -0.60 V. 2 After increasing to [a certain level], it decreased due to the extraction of lithium ions.

[0174] In addition, as shown in FIG. 11, the WO3 electrochromic layers having the Ta2O5 passivation layer of Examples 1 to 4 on top exhibited a CV curve shape similar to that of the electrochromic layer of Comparative Example 1, and the current density decreased as the thickness of the Ta2O5 passivation layer increased. For example, the electrochromic layer having the Ta2O5 passivation layer (50 nm) of Example 2 on top showed -1.29 mA / cm² at -1.0 V. 2 , 0.80 mA / cm at -0.52 V 2 It showed, and the electrochromic layer having the Ta2O5 passivation layer (100 nm) of Example 3 on top showed -1.11 mA / cm at -1.0 V. 2 , 0.72 mA / cm at -0.64 V 2 It represented.

[0175] The reason for such electrochemical differences is interpreted to be due to the solid electrolyte properties of Ta2O5 and its effective passivation role. Specifically, when lithium ions are injected (colored) into the Ta2O5 / WO3 double layer, the passivation layer limits ion penetration into the electrochromic layer, thereby reducing the coloring current density, and this phenomenon becomes more pronounced as the thickness of the passivation layer increases. On the other hand, during decolorization, the amount of extracted penetrating lithium ions decreases, thereby reducing the decolorization current density.

[0177] Referring to FIG. 12, the CV curves of the electrochromic device of Example 2 and the electrochromic device of Comparative Example 1 appeared similar, which means that the electrochromic characteristics according to the lithium ion insertion and extraction mechanisms were identical. Specifically, the electrochromic device of Comparative Example 1 exhibited -1.50 mA / cm² at -1.20 V. 2 , 0.4 mA / cm at -0.58 V 2 It exhibited a current density of, and the electrochromic device of Example 2 showed -1.19 mA / cm at -1.20 V. 2 , 0.58 mA / cm at -0.50 V 2 showed.

[0178] In FIG. 13, the electrochromic device of Comparative Example 1 showed that the area on the graph decreased from the initial cycle, indicating that the electrochromic performance deteriorated rapidly at high temperatures, and color fading also progressed rapidly. In particular, a distinct decrease in current density was observed after the 200th cycle. On the other hand, at room temperature, the electrochromic device of Comparative Example 1 did not show a rapid decrease in area during the initial cycle, confirming that such initial performance degradation was due to high temperatures.

[0179] In contrast, in FIG. 14, the electrochromic device of Example 2 showed excellent long-term stability even under high temperature conditions, as the Ta2O5 passivation layer included in the device greatly improved the heat resistance and structural stability of the device, and there was no significant color change during the cycle.

[0181] Experimental Example 4: Transmittance Measurement

[0182] Transmittance was measured in the wavelength range of 350 to 800 nm using an ultraviolet-visible spectrophotometer (UV / Vis spectrophotometer, Cary 100, Agilent Technologies, USA).

[0183] For the 300 nm WO3 electrochromic layer formed on an ITO-coated glass substrate as described in Comparative Example 1, 0.5 M LiClO4 propylene carbonate electrolyte, ITO-coated glass (working electrode), Pt mesh (counter electrode), Ag / Ag + The transmittance was measured by operating at 25°C using a (reference electrode), and this is shown in Fig. 15.

[0184] In addition, regarding the WO3 electrochromic layer of 300 nm formed on an ITO-coated glass substrate and the Ta2O5 passivation layers of 25, 50, 100, and 200 nm formed on the electrochromic layer, respectively described in Examples 1, 2, 3, and 4, a 0.5 M LiClO4 propylene carbonate electrolyte, ITO-coated glass (working electrode), Pt mesh (counter electrode), and Ag / Ag + The transmittance was measured by operating at 25°C using a (reference electrode), and the results are shown in Figs. 16, 17, 18, and 19, respectively.

[0185] In addition, for the WO3 electrochromic layer 300 nm of Comparative Example 1, the Ta2O5 passivation layer 50 nm formed on the WO3 electrochromic layer 300 nm of Example 2, and the Ta2O5 passivation layer 100 nm formed on the WO3 electrochromic layer 300 nm of Example 3, a graph of optical density change (ΔOD) according to charge density and color change efficiency (η) were obtained and are shown in FIG. 20.

[0186] Meanwhile, with respect to the WO3 electrochromic layer 300 nm formed on an ITO-coated glass substrate as described in Comparative Example 1; and the WO3 electrochromic layer 300 nm formed on an ITO-coated glass substrate as described in Example 2 and the Ta2O5 passivation layer 50 nm formed on the electrochromic layer, 0.5 M LiClO4 propylene carbonate electrolyte, ITO-coated glass (working electrode), Pt mesh (counter electrode), Ag / Ag +Using a reference electrode, the real-time transmittance (in-situ transmittance) according to the number of cycles was measured at 25 ℃, and this is shown in Figs. 21 and 22, respectively.

[0188] Propylene carbonate containing 0.5 M LiClO4 and 0.05 M ferrocene was used as the electrolyte for the electrochromic elements of Comparative Example 1 and Example 2. The transmittance of the electrochromic elements of Comparative Example 1 and Example 2 was measured by operating them at 25°C, and the results are shown in FIGS. 23 and 24.

[0189] In addition, for the electrochromic devices of Comparative Example 1 and Example 2, a graph of the change in optical density (ΔOD) according to charge density and the color change efficiency (η) were obtained and are shown in FIG. 25.

[0190] In addition, for the electrochromic device of Example 2, the real-time transmittance (In-situ transmittance) according to the number of cycles was measured by operating it under conditions of 25 ℃, and this is shown in FIG. 26.

[0192] Referring to Fig. 15, the electrochromic layer without a passivation layer (Comparative Example 1) showed a transmittance of 93.3% in the decolorized state and 6.9% in the colored state at a wavelength of 630 nm, and the transmittance modulation rate ΔT was measured to be 86.4%.

[0193] In FIG. 16, the electrochromic layer (Example 1) having a 25 nm Ta2O5 passivation layer on top exhibited a transmittance of 74.6% in the decolorized state and 10.2% in the colored state at a wavelength of 630 nm, and the transmittance modulation rate ΔT was measured to be 64.4%.

[0194] In FIG. 17, the electrochromic layer (Example 2) with a 50 nm Ta2O5 passivation layer on top exhibited a transmittance of 87.8% in the decolorized state and 14.9% in the colored state at a wavelength of 630 nm, and the transmittance modulation rate ΔT was measured to be 72.9%.

[0195] In FIG. 18, the electrochromic layer (Example 3) with a 100 nm Ta2O5 passivation layer on top exhibited a transmittance of 86.3% in the decolorized state and 23.0% in the colored state at a wavelength of 630 nm, and the transmittance modulation rate ΔT was measured to be 63.3%.

[0196] In FIG. 19, the electrochromic layer (Example 3) with a Ta2O5 passivation layer of 200 nm on top showed a transmittance of 86.2% in the decolorized state and 26.4% in the colored state at a wavelength of 630 nm, and the transmittance modulation rate ΔT was measured to be 59.8%.

[0197] The reason for these optical differences is interpreted to be due to the solid electrolyte properties of Ta2O5 and its effective passivation role. Specifically, when lithium ions were injected (colored) into the Ta2O5 / WO3 double layer, the passivation layer restricted ion penetration into the electrochromic layer, which did not effectively lower the transmittance in the colored state; this phenomenon became more pronounced as the thickness of the passivation layer increased. On the other hand, during decolorization, the amount of extracted penetrating lithium ions was low, so the transmittance in the decolorized state could not be sufficiently increased, and this trend became stronger as the thickness of the passivation layer increased to 50, 100, and 200 nm. Furthermore, at a thickness of 25 nm, interference effects between incident and reflected light occurred due to the thinness of the thickness, and surface roughness and scattering centers existed due to non-uniform growth, resulting in lower transmittance in the decolorized state compared to when the thickness was 50, 100, and 200 nm.

[0198] Meanwhile, as shown in FIG. 20, the coloration efficiency (η) is defined as ΔOD / ΔQ, where ΔOD is the change in optical density (log[T bleached (%) / T colored (%)]), where Q is the charge density (C / cm² 2 ...means. For the WO3 electrochromic layer of Comparative Example 1; the WO3 electrochromic layer and Ta2O5 passivation layer 50 nm of Example 2; and the WO3 electrochromic layer and Ta2O5 passivation layer 100 nm of Example 3, the respective color change efficiencies are 60.89, 50.78, and 46.01 cm⁻¹. 2 It was calculated as / C. In other words, this means that as the thickness of the passivation layer increases, the optical modulation decreases for the same amount of charge.

[0199] Referring to FIGS. 21 and 22, it can be seen that the long-term electrochemical cycle stability of the WO3 electrochromic layer is significantly improved through the Ta2O5 passivation layer. Specifically, the WO3 electrochromic layer 300 nm of Comparative Example 1 began to decline rapidly in the decolorized state starting from the 50th cycle; the transmittance in the decolorized state was 90.3% at the 50th cycle, but decreased to 27.8% at the 1000th cycle. In addition, the transmittance in the colored state fluctuated between 7% and 14%, and accordingly, the transmittance modulation decreased rapidly from 77.8% at the 50th cycle to 20.8% at the 1000th cycle. On the other hand, the 50 nm Ta2O5 passivation layer formed on the 300 nm WO3 electrochromic layer of Example 2 maintained a nearly constant transmittance in the decolorized state at 87.8%, 87.1%, and 86.4% in the 1st, 500th, and 1000th cycles, respectively, so there was no significant change in the transmittance in the decolorized state even after long-term cycles. Similarly, the transmittance in the colored state also remained similar, at 14.6%, 13.2%, and 21.1% in the 1st, 500th, and 1000th cycles, respectively, and the corresponding transmittance modulation was 73.2%, 73.9%, and 65.3%, respectively.

[0201] Referring to FIG. 23, the electrochromic device of Comparative Example 1 exhibited Prussian blue color in the colored state and became transparent in the decolored state. At a wavelength of 630 nm, the transmittance was 70.3% in the decolored state and 9.9% in the colored state, and the transmittance modulation was 60.4%.

[0202] In Fig. 24, the electrochromic device of Example 2 had a transmittance of 73.8% when decolorized and 9.2% when colored at a wavelength of 630 nm, and a transmittance modulation of 64.6%.

[0203] As shown in FIG. 25, the electrochromic devices of Comparative Example 1 and Example 2 have coloration efficiencies (η) of 36.86 and 46.77 cm⁻¹, respectively. 2 It was calculated as / C.

[0204] As can be seen in Fig. 26, the transmittance of the electrochromic device of Example 2 in the decolorized state was 60.2% in the first cycle, but increased to 82.0% in the 3000th cycle, after which the transmittance reached a saturation state. On the other hand, in the colored state, it increased slightly from 8.8% in the first cycle to 12.8% in the 8000th cycle. As a result, excellent long-term stability was demonstrated by maintaining a transmittance modulation of 69.0% even after 8000 repeated tests.

[0206] Experimental Example 5: Evaluation of High Temperature and High Humidity Stability

[0207] In the same manner as the SEM experiment of Experimental Example 1 described above, a WO3 layer of 300 nm was formed on a Si substrate using the same sputtering method used to form the WO3 layer of Example 1, and then the WO3 layer was observed using a scanning electron microscope after being immersed in hot water at 70°C for 30 seconds and 120 seconds, as shown in FIGS. 27 and 28.

[0208] In addition, a 300 nm WO3 layer and a 50 nm Ta2O5 layer were formed sequentially on a Si substrate using the same sputtering method used to form the WO3 layer and Ta2O5 layer of Example 1, and then the Ta2O5 layer was observed using a scanning electron microscope after being immersed in hot water at 70°C for 150 seconds and 600 seconds, as shown in FIGS. 29 and FIGS. 30.

[0209] Then, a 300 nm WO3 layer and a 100 nm Ta2O5 layer were formed sequentially on a Si substrate using the same sputtering method used to form the WO3 layer and Ta2O5 layer of Example 1, and after immersion in hot water at 70°C for 150 seconds and 600 seconds, the Ta2O5 layer was observed using a scanning electron microscope and is shown in FIGS. 31 and 32.

[0210] Finally, in the same manner as the CV experiment of Experimental Example 3, for a WO3 electrochromic layer of 300 nm formed on an ITO-coated glass substrate as described in Comparative Example 1; and a WO3 electrochromic layer of 300 nm formed on an ITO-coated glass substrate as described in Example 2 and a Ta2O5 passivation layer of 50 nm formed on the electrochromic layer, a 0.5 M LiClO4 propylene carbonate electrolyte, ITO-coated glass (working electrode), Pt mesh (counter electrode), and Ag / Ag + Using a reference electrode, CV analysis was performed at room temperature (25°C) after immersion for 150 seconds under hot water conditions at 70°C, and this is illustrated in Fig. 33. At this time, the voltage range was set to -1.0 V to +1.0 V and the scan speed was set to 50 mV / s.

[0212] Referring to FIGS. 27 and 28, very rapid surface degradation was observed in a 300 nm WO3 layer without a passivation layer in hot water at 70 ℃. Specifically, in FIG. 27, large cracks and voids were observed to form on the surface of the WO3 layer after 30 seconds of etching, and in FIG. 28, it was confirmed that the diameter of the voids increased to 100 nm after 120 seconds of etching. As can be seen in the inset photograph, a change in color was observed depending on the etching time. Such a change in color suggests a change in thickness.

[0213] On the other hand, referring to FIGS. 29 to 32, there was no significant change in the surface morphology when both the 300 nm WO3 layer with a 50 nm Ta2O5 layer formed on top and the 300 nm WO3 layer with a 100 nm Ta2O5 layer formed on top were etched for 150 seconds and 600 seconds, respectively.

[0214] Meanwhile, referring to Fig. 33, the WO3 layer without a passivation layer became smaller in area and deformed into a nearly straight line shape due to the decrease in current density in the CV curve after 150 seconds of etching. However, the 300 nm WO3 layer with a 50 nm Ta2O5 layer formed on top, etched under the same conditions, showed a mitigated decrease in current density on the CV curve, with -0.80 mA / cm² at the negative current peak of -1.0 V. 2 , positive current peak at -0.44 V is 0.69 mA / cm 2 It appeared as a similar level to the unetched Ta2O5 and WO3 double layer.

[0215] Ultimately, it was confirmed that the Ta2O5 layer faithfully performs the passivation role, effectively preventing device performance degradation caused by surface degradation due to hydrothermal etching and crystallization problems caused by lithium.

[0217] When combining the aforementioned Experimental Examples 1 to 5, the embodiments including a passivation layer exhibited maximized stability during long-term operation compared to Comparative Example 1, which lacked a passivation layer. Meanwhile, considering transmittance modulation and current density, the passivation thickness is 35 to 75 nm Example 2 within the range was the best.

[0219] Although embodiments of the present invention have been described above, the spirit of the present invention is not limited to the embodiments presented in this specification. Those skilled in the art who understand the spirit of the present invention may easily propose other embodiments within the scope of the same spirit by adding, changing, deleting, or adding components, and such are also to be considered to fall within the scope of the spirit of the present invention. Explanation of the symbols

[0221] 100: Electrochromic element 110: First electrode 120: Electrochromic layer 130: Passivation layer 140: Liquid electrolyte 150: Second electrode

Claims

Claim 1 An electrochromic device comprising: an electrochromic layer provided on a first electrode; a passivation layer provided on the electrochromic layer; a liquid electrolyte provided on the passivation layer; and a second electrode provided on the liquid electrolyte; wherein the passivation layer functions as a barrier between the electrochromic layer and the liquid electrolyte. Claim 2 An electrochromic device according to claim 1, characterized in that the first electrode and / or the second electrode is a transparent electrode. Claim 3 An electrochromic device according to claim 1, characterized in that the electrochromic layer comprises WO3. Claim 4 An electrochromic device according to claim 3, wherein WO3 included in the electrochromic layer is amorphous, and the electrochromic layer is characterized in that no WO3 crystal peak is observed in the XRD graph after 1,000 cycles. Claim 5 An electrochromic device according to claim 1, characterized in that the electrochromic layer has a thickness of 100 to 1000 nm. Claim 6 An electrochromic device according to claim 1, characterized in that the passivation layer comprises Ta2O5. Claim 7 An electrochromic device according to claim 1, characterized in that the passivation layer has a thickness of 20 to 150 nm. Claim 8 An electrochromic device according to claim 1, characterized in that the electrolyte comprises lithium. Claim 9 The electrochromic element according to claim 1, characterized in that the transmittance modulation increases up to 2000 cycles under conditions of a temperature of 25 ℃ and a voltage range of -1.2 to 0 V. Claim 10 In claim 9, the electrochromic element is characterized by having a transmittance modulation of 60% or more at a wavelength of 630 nm after 8,000 cycles under conditions of a temperature of 25 ℃ and a voltage range of -1.2 to 0 V. Claim 11 In claim 1, the electrochromic element has a current density of -1.20 V and -1.5 A / cm² after 200 cycles under conditions of a temperature of 50 ℃ and a voltage range of -1.2 to 0 V. 2 Electrochromic device characterized by the following: Claim 12 A window comprising an electrochromic element according to any one of claims 1 to 11. Claim 13 A display panel comprising an electrochromic element according to any one of claims 1 to 11. Claim 14 (1) a step of forming an electrochromic layer on a first electrode; (2) a step of forming a passivation layer on the electrochromic layer; (3) a step of facing the passivation layer and a second electrode; and (4) a step of supplying a liquid electrolyte between the passivation layer and the second electrode; wherein the passivation layer functions as a barrier between the electrochromic layer and the liquid electrolyte. Claim 15 A method for manufacturing an electrochromic device according to claim 14, characterized in that, in step (2) above, the passivation layer is formed to a thickness of 20 to 150 nm. Claim 16 An electrochromic device manufactured by the manufacturing method of claim 14 or 15.

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