Black electrochromic material and preparation method thereof, and preparation method and application of electrochromic film and device

Abstract

The invention provides a black electrochromic material, a preparation method and application thereof, and a preparation method and application of an electrochromic film and device, and belongs to the technical field of electrochromic materials. The invention provides a black electrochromic material, the chemical general formula of which is MaWbOc, M comprises one or more of Nb, Ni, Mo, Ti, Sn, Eu, Ce, Tb, Ru and Gd; 0 lt; a < = 1, 0lt; b < = 1, 1lt; clt; ct; 4. By reasonably introducing doped metal elements, the energy level structure of the tungsten oxide material can be effectively regulated and controlled, and the optical absorption range of the tungsten oxide material can be expanded, so that wide-range absorption of the tungsten oxide material in a visible light wave band is realized, a colorless-black reversible switching property is shown, absorption of a full-visible spectrum is realized in a color development state, a black effect of the tungsten oxide material is realized, and the application prospect is wide. The application range of the electrochromic material is expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochromic materials, and particularly to a black electrochromic material, a preparation method and application thereof, a preparation method and application of an electrochromic film and a device. Background Art

[0002] Electrochromic materials are a class of intelligent optical modulation materials that have attracted much attention in recent years. Their optical properties (color, transmittance, reflectance, absorbance, etc.) can be reversibly switched under the action of an electric field. Based on the above characteristics, such materials have important application values in the fields of smart windows, reflection / transmission displays, anti-glare rearview mirrors, etc. Tungsten oxide materials, as one of the electrochromic materials with the earliest research time and the widest application, have the advantages of excellent environmental stability and wide optical modulation range, and have been successfully used in products such as building curtain walls and aircraft windows. However, due to the limitations of its own material structure and energy band characteristics, tungsten oxide materials usually show a reversible switch between colorless and blue under the action of an electric field. This single optical switch from colorless to blue causes it to be unable to maintain the color of the observed object itself (color deviation) in the colored state and lose its original displayed color. Moreover, blue-phase glass generally lacks the absorption of light in the 400-500 nm wavelength band, resulting in relatively limited modulation of the solar spectrum by the smart color-changing glass. In addition, when electrochromic materials are applied to some special scenarios, such as electronic price tags, electronic billboards, anti-glare rearview mirrors, smart electronic sunglasses, etc., a black color display effect is generally necessary. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a black electrochromic material, a preparation method and application thereof, a preparation method and application of an electrochromic film and a device. The black electrochromic material provided by the present invention has a wide range of absorption in the visible light band and exhibits a reversible switching property between colorless and black.

[0004] To achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0005] The present invention provides a black electrochromic material with a chemical general formula of M a W b O c , where M includes one or more of Nb, Ni, Mo, Ti, Sn, Eu, Ce, Tb, Ru, and Gd; 0 < a ≤ 1, 0 < b ≤ 1, 1 < c < 4, where a, b, and c represent the number of atoms.

[0006] Preferably, the M includes Nb and Mo.

[0007] The present invention also provides a preparation method of the black electrochromic material according to the above technical solution, including the following steps:

[0008] Mix a tungsten source, a doped metal source and a solvent to carry out a solvothermal reaction to obtain the black electrochromic material, and the doped metal source provides M.

[0009] Preferably, the molar ratio of tungsten element in the tungsten source to metal element in the doped metal source is 1:10 to 10:1.

[0010] Preferably, the temperature of the solvothermal reaction is 200 to 300 °C, and the heat preservation time is 2 to 5 h.

[0011] The present invention also provides an application of the black electrochromic material described in the above technical solution or the black electrochromic material prepared by the preparation method described in the above technical solution in the field of electrochromic devices.

[0012] The present invention also provides an electrochromic film, which includes a conductive glass and an electrochromic material loaded on the surface of the conductive glass, and the electrochromic material is the black electrochromic material described in the above technical solution or the black electrochromic material prepared by the preparation method described in the above technical solution.

[0013] The present invention also provides a preparation method of the electrochromic film described in the above technical solution, including the following steps:

[0014] Mix the electrochromic material with a dispersant to obtain a dispersion liquid;

[0015] Coat the dispersion liquid on the surface of the conductive glass and then carry out calcination to obtain the electrochromic film.

[0016] Preferably, the temperature of the calcination is 350 to 650 °C, and the heat preservation time is 1 to 10 h.

[0017] The present invention also provides an electrochromic device, which includes a film, an electrolyte functional layer, an ion storage layer and a conductive glass stacked in sequence, the film is the electrochromic film described in the above technical solution or the electrochromic film prepared by the preparation method described in the above technical solution, and the electrolyte functional layer is arranged on the surface of the electrochromic material.

[0018] The present invention provides a black electrochromic material with a chemical general formula of M a W b O c , where M includes one or more of Nb, Ni, Mo, Ti, Sn, Eu, Ce, Tb, Ru and Gd; 0 < a ≤ 1, 0 < b ≤ 1, 1 < c < 4, where a, b and c represent the number of atoms.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] The present invention can effectively regulate the energy level structure of tungsten oxide materials and expand their optical absorption range by the reasonable introduction of doped metal elements, thereby achieving wide-range absorption in the visible light band, showing the reversible switching property of colorless-black, and then achieving absorption of the entire visible spectrum in the color-developing state, achieving its black effect, and expanding the application scope of electrochromic materials. The black electrochromic material of the present invention can realize the reversible switching between colorless and neutral black of tungsten oxide-based materials controlled by voltage, with a wider spectrum regulation range and higher photothermal regulation efficiency. Moreover, compared with blue smart glass, the color of the object itself can be observed through this glass, which has a better observation experience. In addition, the black color rendering effect has indispensable application value in the fields of e-books, electronic ink screens, etc.

[0021] The present invention also provides a method for preparing the black electrochromic material described in the above technical solution, which utilizes a solution method to prepare the black electrochromic material, thereby avoiding the use of expensive equipment, effectively reducing the material preparation cost, and promoting its large-scale application. It has certain advantages in large-area device preparation, process cost reduction, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention is a flow chart of the preparation of the electrochromic film;

[0023] Figure 2 It is a schematic diagram of the structure of the electrochromic film of the present invention;

[0024] Figure 3 It is a schematic structural diagram of the electrochromic device of the present invention;

[0025] Figure 4 The transmission spectra of the electrochromic film prepared in Example 1 in the colorless state and the colored state;

[0026] Figure 5 The photograph of the electrochromic film prepared in Example 1 in the colored state and its Lab value;

[0027] Figure 6 The transmission spectrum of the electrochromic device prepared in Example 1 in the colored state, its photograph and the corresponding Lab value;

[0028] Figure 7 The reversibility and memory effect curves of the electrochromic device prepared in Example 1;

[0029] Figure 8 The transmission spectra of the comparative tungsten oxide film at different voltages;

[0030] Fig. 9 The following are photos of the comparative example tungsten oxide film in the colorless state and the colored state and their Lab values. DETAILED DESCRIPTION

[0031] The present invention provides a black electrochromic material with a chemical general formula of M a W b O c , where M includes one or more of Nb, Ni, Mo, Ti, Sn, Eu, Ce, Tb, Ru, and Gd; 0 < a ≤ 1, 0 < b ≤ 1, 1 < c < 4, and a, b, and c represent the number of atoms.

[0032] In the present invention, a is preferably 0 < a ≤ 0.5, b is preferably 0.5 ≤ b < 1, and c is preferably 2 < c < 4.

[0033] In a specific embodiment of the present invention, the chemical general formula of the black electrochromic material may specifically be Ni 0.5 WO3, MoW 0.5 O3, Nb 0.5 WO3, Mo 0.5 Nb 0.5 W 0.5 O3, Ni 0.4 WO3, or Ni 0.6 WO3.

[0034] In the present invention, M preferably includes Nb and Mo. When M includes Nb and Mo, the molar ratio of Nb to Mo is preferably 1:1.

[0035] In a specific embodiment of the present invention, M may specifically be Nb, Ni, or Mo.

[0036] In the present invention, the structure of the black electrochromic material is preferably amorphous or crystalline, and the crystalline form may specifically be monoclinic, tetragonal, trigonal, or orthorhombic.

[0037] The present invention also provides a preparation method of the black electrochromic material according to the above technical solution, including the following steps:

[0038] Mix a tungsten source, a doping metal source, and a solvent and perform a solvothermal reaction to obtain the black electrochromic material, where the doping metal source provides M.

[0039] In the present invention, unless otherwise specified, the raw materials used are all commercially available products in the art.

[0040] In the present invention, the doping metal source preferably includes a nickel source, a niobium source, a molybdenum source, a titanium source, a Sn source, a europium source, a cerium source, a terbium source, a ruthenium source, or a gadolinium source; the nickel source preferably includes nickel chloride and / or nickel acetate, the niobium source preferably includes niobium chloride and / or ammonium niobate, and the molybdenum source preferably includes molybdenum chloride and / or ammonium molybdate.

[0041] In the present invention, the tungsten source is preferably ammonium metatungstate.

[0042] In the present invention, the molar ratio of the tungsten element in the tungsten source to the metal element in the doped metal source is preferably 1:10 to 10:1, specifically 10:1, 5:1, 2:1, 1:1, 1:2, 1:5 or 1:10; when the M preferably includes Nb and Mo, the molar ratio of the tungsten element in the tungsten source, the Nb element in the doped metal source and the Mo element in the doped metal source is preferably 1:1:1.

[0043] In the present invention, the solvent is preferably a high boiling point solvent, and the high boiling point solvent may be oleylamine, oleic acid, hexadecylamine or octadecylamine.

[0044] In the present invention, the usage ratio of the tungsten source to the solvent is preferably 0.5-2 mmol:20-80 mL.

[0045] After the mixing is completed, the present invention preferably performs vacuum degassing on the obtained mixed solution.

[0046] In the present invention, the vacuum degassing temperature is preferably 70-160° C., specifically 70, 80, 90, 100, 110, 120, 130, 140, 150 or 160° C., and the time is preferably 10 min.

[0047] In the present invention, the temperature of the solvothermal reaction is preferably 200-300° C., specifically 200, 250 or 300° C., and the insulation time is preferably 2-5 h, specifically 2, 3, 4 or 5 h.

[0048] In the present invention, the solvothermal reaction is preferably carried out in a nitrogen atmosphere.

[0049] After the solvothermal reaction is completed, the present invention preferably cools the obtained solvothermal reaction product naturally to room temperature, and then sequentially washes and performs solid-liquid separation to obtain the black electrochromic material.

[0050] In the present invention, the detergent used in the washing is preferably a polar solvent, and the polar solvent may specifically be ethanol or methanol.

[0051] In the present invention, the solid-liquid separation is preferably centrifugation, and the centrifugal speed is preferably 5000-12000 rpm, specifically 5000, 6000, 7000, 8000, 9000, 10000, 11000 or 12000 rpm, the number of times is preferably 3-5 times, and the time of each time is preferably 10-20 min, specifically 10, 15 or 20 min.

[0052] The present invention also provides the use of the black electrochromic material described in the above technical solution or the black electrochromic material prepared by the preparation method described in the above technical solution in the field of electrochromic devices.

[0053] The present invention also provides an electrochromic film, comprising conductive glass and an electrochromic material loaded on the surface of the conductive glass, wherein the electrochromic material is the black electrochromic material described in the above technical solution or the black electrochromic material prepared by the preparation method described in the above technical solution.

[0054] Figure 2 The structure diagram of the electrochromic film of the present invention comprises a conductive glass and an electrochromic material (M) loaded on the surface of the conductive glass. a W b O c membrane).

[0055] In the present invention, the conductive glass is preferably indium tin oxide (ITO) or fluorine-doped tin dioxide (FTO).

[0056] In the present invention, the thickness of the electrochromic material is preferably 20 nm to 10 μm.

[0057] The present invention also provides a method for preparing the electrochromic film described in the above technical solution, comprising the following steps:

[0058] mixing the electrochromic material with a dispersant to obtain a dispersion;

[0059] The dispersion is coated on the surface of conductive glass and then calcined to obtain the electrochromic film.

[0060] Figure 1 The present invention is a flow chart for preparing the electrochromic film.

[0061] The present invention mixes the electrochromic material with a dispersant to obtain a dispersion.

[0062] In the present invention, the dispersant is preferably a non-polar solvent, specifically toluene or n-hexane.

[0063] In the present invention, the usage ratio of the electrochromic material to the dispersant is preferably 1:10 to 50 mL.

[0064] After obtaining the dispersion, the present invention applies the dispersion on the surface of the conductive glass and then calcines it to obtain the electrochromic film.

[0065] In the present invention, the coating is preferably performed by blade coating, spin coating or spray coating.

[0066] In the present invention, the calcination (high-temperature calcination) temperature is preferably 350-650°C, specifically 350, 400, 450, 500, 550, 600 or 650°C, and the insulation time is preferably 1-10h, specifically 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10h; the calcined product can be reversibly switched between colorless and black under the action of voltage.

[0067] In the present invention, the electrochromic film is preferably used in anti-glare rearview mirrors, building curtain walls, automobile skylights, electronic tags or electronic billboards.

[0068] The present invention also provides an electrochromic device, comprising a film, an electrolyte functional layer, an ion storage layer and a conductive glass stacked in sequence, wherein the film is the electrochromic film described in the above technical solution or the electrochromic film prepared by the preparation method described in the above technical solution, and the electrolyte functional layer is arranged on the surface of the electrochromic material.

[0069] Figure 3 It is a schematic structural diagram of the electrochromic device of the present invention.

[0070] The electrochromic device provided by the present invention comprises an electrolyte functional layer, and the thickness of the electrolyte functional layer is preferably 0.1 to 100 μm.

[0071] In the present invention, the electrolyte functional layer comprises a membrane-forming material and an ion-conducting material, and the mass ratio of the membrane-forming material to the ion-conducting material is preferably 10: 1 to 10000: 1. In a specific embodiment of the present invention, the electrolyte functional layer is a Nafion membrane.

[0072] In the present invention, the film-forming material is preferably made of an acrylate polymer; the ion conductive material includes an imidazole ionic liquid and / or a metal salt.

[0073] The electrochromic device provided by the present invention comprises an ion storage layer.

[0074] In the present invention, the thickness of the ion storage layer is preferably 0.1 to 100 μm.

[0075] In the present invention, the material of the ion storage layer is preferably nickel oxide and / or titanium dioxide.

[0076] In the present invention, the conductive glass is preferably indium tin oxide (ITO) or fluorine-doped tin dioxide (FTO).

[0077] The present invention also provides a method for preparing the electrochromic device described in the above technical solution, comprising the following steps:

[0078] An ion storage layer is deposited on the surface of the conductive glass by a coating method, and then an electrolyte functional layer is prepared on the surface of the ion storage layer. The conductive glass loaded with the ion storage layer and the electrolyte functional layer is laminated to the electrochromic film to obtain the electrochromic device, which can reversibly switch between colorless and black.

[0079] In the present invention, the coating method is preferably magnetron sputtering, vacuum evaporation or solution coating. The present invention has no special limitation on the specific parameters of the coating method, and the coating method may be used in a manner familiar to those skilled in the art.

[0080] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0081] Example 1

[0082] Film preparation process: Mix the tungsten source (ammonium metatungstate, 0.5mmol) and the doped metal source (nickel source, nickel acetate) at a molar ratio of tungsten to nickel of 2:1, stir and dissolve in 50mL of oleylamine, then vacuum degas at 120℃ for 10min, heat to 250℃ under nitrogen protection, keep at 250℃ for 2h and cool naturally. After cooling to room temperature, add 50mL of ethanol, centrifuge (10000rpm, time 10min) 3 times, and disperse in 20mL of toluene to obtain a nickel-containing tungsten oxide-based black electrochromic material (chemical formula Ni 0.5 WO3) dispersion. Then, it was coated (scraped) onto the surface of conductive glass (FTO) and calcined at 500°C for 5 hours. After calcination, a film loaded with nickel-containing tungsten oxide-based black electrochromic material (nickel-tungsten molar doping ratio of 1:2) with a thickness of 1μm was obtained. The calcined film can reversibly switch between colorless and black under the action of voltage. The spectral switching properties, photos of the film, and Lab values ​​are shown in Figure 2. Figures 4-5 shown. Figure 4 The transmission spectra of the electrochromic film prepared in Example 1 in the colorless state and the colored state, Figure 5 The photograph of the electrochromic film prepared in Example 1 in the colored state and its Lab value.

[0083] Based on the electrochromic film prepared in this embodiment, two electrochromic devices were prepared using nickel oxide as the ion storage layer and Nafion membrane as the electrolyte functional layer. The specific preparation method is as follows:

[0084] An ion storage layer is deposited on the surface of the conductive glass by magnetron sputtering, and then an electrolyte functional layer is bonded to the surface of the ion storage layer. The resulting conductive glass loaded with the ion storage layer and the electrolyte functional layer is bonded to the electrochromic film prepared in Example 1 to obtain an electrochromic device.

[0085] The device's coloring spectrum, photos and Lab values ​​were tested. The device was black in the coloring state ( Figure 6 ), and has good reversibility and memory effect ( Figure 7 ).

[0086] Example 2

[0087] Preparation process: Mix the tungsten source (ammonium metatungstate, 0.5mmol) and the doped metal source (molybdenum source, ammonium molybdate) at a molar ratio of 1:2 and stir to dissolve in 50mL of oleylamine, then vacuum degas at 110°C for 10min, heat to 230°C under nitrogen protection, keep at 230°C for 3h and cool naturally. After cooling to room temperature, add 50mL of ethanol, centrifuge (10000rpm, time 10min) 3 times, and disperse in 20mL of toluene to obtain a molybdenum-containing tungsten oxide-based electrochromic material (chemical formula MoW 0.5 O3) dispersion. Then, it was coated (scraped) on the surface of conductive glass (fluorine-doped tin dioxide) and calcined at high temperature. The calcination temperature was 400°C for 4 hours. After the calcination was completed, a film loaded with molybdenum-containing tungsten oxide-based black electrochromic material was obtained with a thickness of 1 μm. The calcined film can be reversibly switched between colorless and black under the action of voltage. Its Lab values ​​in the faded state and the colored state are shown in Table 2 below.

[0088] Example 3

[0089] Preparation process: Mix the tungsten source (ammonium metatungstate, 0.5mmol) and the doped metal source (niobium source, niobium acetate) at a molar ratio of tungsten to niobium of 2:1, stir and dissolve in 50mL of oleylamine, then vacuum degas at 120℃ for 10min, heat to 300℃ under nitrogen protection, keep at 300℃ for 2h and cool naturally. After cooling to room temperature, add 500mL of ethanol, centrifuge (10000rpm, time 10min) 3 times, and disperse in 200mL of toluene to obtain a molybdenum-containing tungsten oxide-based electrochromic material (chemical formula Nb 0.5WO3) dispersion. Then, it was coated (scraped) on the surface of conductive glass (fluorine-doped tin dioxide) and calcined at high temperature. The calcination temperature was 500°C for 4 hours. After the calcination was completed, a film loaded with niobium tungsten oxide-based black electrochromic material was obtained with a thickness of 2μm. The calcined film can be reversibly switched between colorless and black under the action of voltage. Its Lab values ​​in the faded state and the colored state are shown in Table 2 below.

[0090] Example 4

[0091] Preparation process: Mix the tungsten source (ammonium metatungstate, 0.5mmol) and the doped metal source (molybdenum source, ammonium molybdate; niobium source, niobium acetate) at a molar ratio of 1:1:1, stir and dissolve in 50mL of oleylamine, then vacuum degas at 130℃ for 10min, heat to 260℃ under nitrogen protection, keep at 260℃ for 1h and cool naturally. After cooling to room temperature, add 50mL of ethanol, centrifuge (10000rpm, time 10min) 3 times, and disperse in 20mL of toluene to obtain a tungsten oxide-based electrochromic material containing molybdenum and niobium (chemical formula Mo 0.5 Nb 0.5 W 0.5 O3) dispersion. Then, it was coated (scraped) on the surface of conductive glass (fluorine-doped tin dioxide) and calcined at high temperature. The calcination temperature was 550°C for 6 hours. After the calcination was completed, a film loaded with molybdenum-niobium tungsten oxide-based black electrochromic material was obtained with a thickness of 1.5μm. The calcined film can be reversibly switched between colorless and black under the action of voltage. Its Lab values ​​in the faded state and the colored state are shown in Table 1 below.

[0092] It can be seen from Table 1 that the different films of the present invention can achieve switching between a neutral transparent colorless state and a neutral black color state.

[0093] Table 1 Lab values ​​of films in Examples 2 to 4 in faded and colored states

[0094]

[0095] Example 5

[0096] The same technical scheme as in Example 1 was adopted, and the amount of nickel acetate was changed to obtain electrochromic films with nickel-tungsten molar doping ratios of 2:5 and 3:5, respectively. The chemical formulas were Ni 0.4 WO3 and Ni 0.6WO3, the Lab values ​​of different nickel-doped tungsten oxide films in the colored state are shown in Table 2. It can be seen that for the same doped metal element, different molar ratios have a great influence on the Lab value of the film colored state. When the nickel-tungsten molar doping ratio reaches 2:5, its colored state is still blue, when the nickel-tungsten molar doping ratio reaches 1:2, the colored state is black, and when the nickel-tungsten molar doping ratio is higher (3:5), the colored state is black, but the elements are easy to separate.

[0097] Table 2 Lab values ​​of different nickel-doped tungsten oxide films in the colored state

[0098]

[0099]

[0100] Comparative Example: Pure tungsten oxide electrochromic material without metal doping.

[0101] Preparation process: Stir and dissolve the tungsten source (ammonium metatungstate, 0.5mmol) in 50mL of oleylamine, then vacuum degas at 120℃ for 10min, heat to 250℃ under nitrogen protection and keep warm for 2h, then cool naturally. After cooling to room temperature, add 50mL of ethanol, centrifuge (speed 12000rpm, time 10min) 3 times, and disperse in 50mL of toluene to obtain a dispersion containing pure tungsten oxide electrochromic material. Then, apply (scrape) it to the surface of conductive glass (fluorine-doped tin dioxide), and calcine at high temperature. The calcination temperature is 500℃, and the time is 5h. After calcination, a film loaded with pure tungsten oxide-based electrochromic material is obtained, with a thickness of 10μm. The calcined film can reversibly switch between colorless and blue under the action of voltage, and lacks specific absorption between 400 and 500nm.

[0102] The spectral switching properties and color switching properties of pure tungsten oxide-based electrochromic materials are as follows: Figure 8 and Fig. 9 As shown, pure tungsten oxide can only achieve reversible switching between colorless and blue.

[0103] In summary, the present invention can solve the problem that it is difficult for existing electrochromic materials to achieve black in the coloring state when used. By introducing appropriate metal elements in the synthesis process of tungsten oxide electrochromic materials, changing their energy level structure, expanding their absorption range in the coloring state, and then achieving absorption of the entire visible spectrum in the coloring state, achieving their black effect, and expanding the application range of electrochromic materials.

[0104] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A black electrochromic material, characterized in that: The chemical general formula is M a W b O c , where M includes one or more of Nb, Ni, Mo, Ti, Sn, Eu, Ce, Tb, Ru, and Gd; 0 < a ≤ 1, 0 < b ≤ 1, 1 < c < 4, where a, b, and c represent the number of atoms.

2. The black electrochromic material according to claim 1, characterized in that: The M includes Nb and Mo.

3. The method for preparing the black electrochromic material according to claim 1 or 2, characterized in that: The following steps are involved: A tungsten source, a doping metal source and a solvent are mixed to perform a solvothermal reaction to obtain the black electrochromic material, wherein the doping metal source provides M.

4. The preparation method according to claim 3, characterized in that: The molar ratio of the tungsten element in the tungsten source to the metal element in the doping metal source is 1:10 to 10:

1.

5. The preparation method according to claim 3, characterized in that: The temperature of the solvent thermal reaction is 200-300° C., and the insulation time is 2-5 hours.

6. Use of the black electrochromic material according to claim 1 or 2 or the black electrochromic material prepared by the preparation method according to any one of claims 3 to 5 in the field of electrochromic devices.

7. An electrochromic film, characterized in that: The invention comprises conductive glass and an electrochromic material loaded on the surface of the conductive glass, wherein the electrochromic material is the black electrochromic material according to claim 1 or 2 or the black electrochromic material prepared by the preparation method according to any one of claims 3 to 5.

8. The method for preparing the electrochromic film according to claim 7, characterized in that: The following steps are involved: mixing the electrochromic material with a dispersant to obtain a dispersion; The dispersion is coated on the surface of conductive glass and then calcined to obtain the electrochromic film.

9. The preparation method according to claim 8, characterized in that: The calcination temperature is 350-650° C., and the heat preservation time is 1-10 hours.

10. An electrochromic device, characterized in that: The invention comprises a film, an electrolyte functional layer, an ion storage layer and a conductive glass which are stacked in sequence, wherein the film is the electrochromic film according to claim 7 or the electrochromic film prepared by the preparation method according to claim 8 or 9, and the electrolyte functional layer is arranged on the surface of the electrochromic material.

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