Single-component dual-band electrochromic film and preparation method thereof

Abstract

The invention relates to the technical field of electrochromism, in particular to a single-component dual-band electrochromism film and a preparation method thereof.The preparation method comprises the steps that an electrochromism material is deposited on one side of a substrate in an electron beam thermal evaporation mode to form an electrochromism layer in a first crystalline state, the electrochromic layer in the first crystalline state and the substrate together form a layer group. And heating the layer group in the air atmosphere for a first set time at a set temperature so as to carry out air thermal oxidation. And taking out the layer group subjected to air thermal oxidation, and cooling to room temperature, so that the electrochromic layer in the first crystalline state is changed into the electrochromic layer in the second crystalline state, and the single-component dual-band electrochromic film is prepared. Therefore, the single-component dual-band electrochromic film obtained by the preparation method is high in optical contrast.

Description

Technical Field

[0001] The invention belongs to the technical field of electrochromic technology, and in particular relates to a single-component dual-band electrochromic film and a preparation method thereof. Background Art

[0002] Against the backdrop of a rapidly growing world population and industrial modernization, building energy consumption continues to increase, accounting for more than 40% of the world's total energy consumption. Compared with traditional electrochromic films, dual-band electrochromic films are an active photothermal modulation material that can independently and selectively adjust visible light and near-infrared light to achieve a wide range of solar radiation modulation, effectively reducing the use of indoor temperature control facilities and reducing energy consumption.

[0003] In 2013, DJ Milliron et al. studied glass nanocrystalline composites based on indium tin oxide (ITO) nanocrystals and amorphous niobium oxide (NbOx). Indium tin oxide nanocrystals modulate near-infrared light through free carrier density and localized surface plasmon resonance (LSPR) absorption, while amorphous niobium oxide modulates visible light through polarization absorption. Since then, some nanocomposites have been shown to have dual-band electrochromic modulation properties, but the preparation process is too complicated. WO3, as a single-component material, has special tunneling and excellent current carrying capacity. Studies have shown that oxygen vacancy WO prepared by liquid phase method 3-x Nanocrystals or nanowires can simultaneously achieve controllable regulation of visible light and near-infrared light, which has opened up a research boom in single-component dual-band electrochromic materials. Relevant studies at home and abroad have shown that the performance of single-component dual-band electrochromic materials depends largely on the preparation process and the microstructure of the final film. At present, the synthesis and preparation of single-component dual-band electrochromic nanomaterials mainly adopt chemical synthesis methods such as liquid phase method, chemical bath deposition method, electrochemical deposition method, spray pyrolysis method, sol-gel method, hydrothermal method and solvent thermal synthesis method. However, the preparation of large-area uniform, high-quality and strong thin films on conductive substrates is still a challenge for chemical synthesis of nanomaterials. Traditional physical vapor deposition methods, such as electron beam evaporation, are difficult to directly prepare nanomaterials and difficult to regulate the micro-optical structure of nanomaterials such as size.

[0004] The current single-component dual-band electrochromic layer usually has problems such as complex preparation methods, uneven film layers, low optical contrast, and poor partition modulation effects, which seriously hinder its solar thermal modulation performance and its application in energy-saving buildings. Therefore, it is urgent to develop a preparation scheme for a single-component dual-band electrochromic material with large-area uniform and efficient full solar spectrum modulation capabilities. Summary of the invention

[0005] In view of this, the present invention aims to provide a single-component dual-band electrochromic film and a preparation method thereof. The single-component dual-band electrochromic film obtained by the preparation method has high optical contrast.

[0006] To achieve the above object, the technical solution created by the present invention is implemented as follows: A method for preparing a single-component dual-band electrochromic film, comprising: Depositing the electrochromic material on one side of the substrate by electron beam thermal evaporation to form a first crystalline electrochromic layer, wherein the first crystalline electrochromic layer and the substrate together form a layer group; heating the layer group in the air atmosphere for a first set time at a set temperature to perform air thermal oxidation; The layer group after air thermal oxidation is taken out and cooled to room temperature, so that the electrochromic layer in the first crystalline state is changed into the electrochromic layer in the second crystalline state, thereby preparing a single-component dual-band electrochromic film.

[0007] Furthermore, the electrochromic material is deposited on one side of the substrate by electron beam thermal evaporation to form a first crystalline electrochromic layer, comprising: The electrochromic material and the substrate are placed inside a coating device, the inside of the coating device is evacuated to a set pressure, and the electrochromic material is deposited on one side of the substrate by electron beam evaporation at room temperature to form a first crystalline electrochromic layer.

[0008] Furthermore, the pressure is set to 2.5×10 -3 Pa~2.8×10 -3 Pa.

[0009] Further, an electrochromic material is deposited on one side of the substrate by electron beam evaporation to form a first crystalline electrochromic layer, comprising: The electron beam is directed onto the electrochromic material, and the electron beam is adjusted so that the rate of evaporating the electrochromic material is maintained at a set rate, and the evaporation is continued for a second set time.

[0010] Further, the rate is set to 0.1 nm / s to 0.5 nm / s; and / or The second set time is greater than or equal to 30 minutes.

[0011] Further, the temperature is set to 400°C to 450°C; and / or The first setting time is 30min~1000min; and / or The electrochromic material is tungsten trioxide.

[0012] A single-component dual-band electrochromic film is prepared by the above preparation method. The single-component dual-band electrochromic film comprises a substrate and a second crystalline electrochromic layer.

[0013] Furthermore, the thickness of the electrochromic layer in the second crystalline state is 100 nm to 1000 nm.

[0014] Furthermore, the second crystalline state is high-purity monoclinic nanocrystals; the average grain size of the nanocrystals in the high-purity monoclinic nanocrystals is 7nm~10nm.

[0015] Furthermore, the substrate includes a transparent conductive layer and a base plate, and the second crystalline electrochromic layer is located on a side of the transparent conductive layer facing away from the base plate.

[0016] Compared with the prior art, the invention can achieve the following beneficial effects: the preparation method of the single-component dual-band electrochromic film created by the invention uses electron beam thermal evaporation to deposit the electrochromic material on one side of the substrate to form a first crystalline electrochromic layer, so that the prepared electrochromic layer is more uniform and firm. Afterwards, the layer group formed by the first crystalline electrochromic layer and the substrate is subjected to air thermal oxidation, so that the size, microstructure and crystal system of the first crystalline electrochromic layer can be adjusted to make the first crystalline electrochromic layer become the second crystalline electrochromic layer. The air thermal oxidation method is used to make the preparation method of the second crystalline electrochromic layer simpler. And the obtained single-component dual-band electrochromic film has an optical contrast of 95% at a wavelength of 1300nm, which exceeds the maximum infrared optical contrast of the existing single-component dual-band electrochromic film. It can also achieve zoned regulation of the visible light band and near-infrared light band from 380nm to 2500nm, with a large optical adjustment range and excellent zoned modulation effect of visible light and infrared light. It can achieve three independent photothermal regulation modes of bright, cold and dark under different driving potentials. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings: Figure 1 A schematic diagram of a single-component dual-band electrochromic film according to an embodiment of the present invention; Figure 2 A flow chart of a method for preparing a single-component dual-band electrochromic film according to an embodiment of the present invention; Figure 3 A TEM image of the electrochromic layer of the second crystalline state of the single-component dual-band electrochromic film described in an embodiment of the present invention; Figure 4A schematic diagram of the average response time of coloring and the average response time of fading of the second crystalline electrochromic layer of the single-component dual-band electrochromic film described in an embodiment of the present invention under visible light and near-infrared light; Figure 5 A schematic diagram of the coloring efficiency value of the electrochromic layer of the second crystalline state of the single-component dual-band electrochromic film according to an embodiment of the present invention; Figure 6 A schematic diagram showing the transmittance comparison between the single-component dual-band electrochromic film described in the embodiment of the present invention and the single-component dual-band electrochromic film of the comparative example under different potential control.

[0018] Description of reference numerals: Substrate 10; electrochromic layer 11; layer group 12; transparent conductive layer 13; base plate 14; single-component dual-band electrochromic film 15. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the invention clearer, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the invention and do not constitute a limitation to the invention. Similar components in different embodiments use associated similar component numbers. In the following embodiments, many detailed descriptions are to enable the invention to be better understood. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other components, materials, and methods. In some cases, some operations related to the invention are not shown or described in the specification, in order to avoid the core part of the invention being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0020] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other to form various implementation methods. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a necessary sequence, unless otherwise specified that a certain sequence must be followed.

[0021] In the description of the invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention, unless otherwise specified, the meaning of "multiple" is two or more.

[0022] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0023] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0024] See also Figure 1 and Figure 2 As shown, a method for preparing a single-component dual-band electrochromic film includes steps S101 to S103.

[0025] In step S101, an electrochromic material is deposited on one side of a substrate 10 by electron beam thermal evaporation to form a first crystalline electrochromic layer 11. The first crystalline electrochromic layer 11 and the substrate 10 together form a layer group 12, that is, the layer group 12 includes the first crystalline electrochromic layer 11 and the substrate 10. Among them, the electrochromic material is tungsten trioxide (WO3). The substrate 10 may include a transparent conductive layer 13 and a substrate 14. The transparent conductive layer 13 is deposited on one side of the substrate 14, and the electrochromic layer 11 is deposited on the side of the transparent conductive layer 13 away from the substrate 14. The material of the substrate 14 may be glass, such as K9 glass or quartz glass. The material of the transparent conductive layer 13 may be cerium-doped indium oxide (ICO). The thickness of the transparent conductive layer 13 is greater than or equal to 100nm.

[0026] In one embodiment, step S101 includes: placing the electrochromic material and the substrate 10 inside a coating device, evacuating the inside of the coating device to a set pressure, and at room temperature, depositing the electrochromic material on one side of the substrate 10 by electron beam evaporation to form a first crystalline electrochromic layer 11. The coating device may be an electron beam coating machine. The set pressure is 2.5×10 -3 Pa~2.8×10 -3 In this embodiment, the pressure is set to 2.8×10 -3 Pa.

[0027] In one embodiment, an electrochromic material is deposited on one side of a substrate 10 by electron beam evaporation to form a first crystalline electrochromic layer 11, including: applying an electron beam to the electrochromic material, adjusting the electron beam so that the rate of evaporating the electrochromic material is maintained at a set rate, and continuing the evaporation for a second set time. The electron beam can be adjusted by adjusting the size and position of the light spot on the electrochromic material where the electron beam is applied. The set rate is 0.1 nm / s to 0.5 nm / s. The second set time is greater than or equal to 30 min. In this embodiment, the set rate is 0.2 nm / s, and the second set time is 30 min. The thickness of the electrochromic layer 11 deposited on one side of the substrate 10 can be 110 nm to 1010 nm. When the electrochromic material used is WO3, amorphous WO can be obtained after deposition. 3-x The electrochromic layer 11, that is, the first crystalline state is amorphous.

[0028] In step S102, at a set temperature, the layer group 12 in the air atmosphere is heated for a first set time to perform air thermal oxidation. A vacuum tube furnace can be selected, and the temperature inside the vacuum tube furnace can be increased to the set temperature. The interior of the vacuum tube furnace is an air atmosphere. Then the layer group 12 is placed inside the vacuum tube furnace, and the layer group 12 can be placed at the center of the interior of the vacuum tube furnace, and the layer group 12 is heated for a first set time. Among them, the layer group 12 can be placed in a high temperature resistant ceramic crucible. The set temperature is 400°C to 450°C. In this embodiment, the set temperature is 450°C. The first set time is 30min to 1000min. In this embodiment, the first set time is 30min.

[0029] In step S103, the layer group 12 after air thermal oxidation is taken out and cooled to room temperature, so that the first crystalline electrochromic layer 11 is changed into the second crystalline electrochromic layer 11, thereby preparing a single-component dual-band electrochromic film 15. The single-component dual-band electrochromic film 15 includes a substrate 10 and an electrochromic layer 11. The layer group 12 after air thermal oxidation is taken out and can be placed indoors to cool to room temperature. The thickness of the electrochromic layer 11 after cooling can be changed to 100nm~1000nm. When the electrochromic material used is WO3, after steps S102 and S103, the amorphous WO 3-x The electrochromic layer 11 is changed into high-purity monoclinic WO 3-x The nanocrystalline electrochromic layer 11, that is, the second crystalline state is a high-purity monoclinic nanocrystal. 3-x The average grain size of nanocrystals is 7nm~10nm.

[0030] In this embodiment, the tungsten trioxide powder and the substrate 10 are placed inside the electron beam coating machine, and the inside of the electron beam coating machine is evacuated to 2.8×10 -3 Pa, and at room temperature, an electron beam is directed onto tungsten trioxide, and the electron beam is adjusted so that the rate of evaporation of tungsten trioxide is maintained at 0.2nm / s, and the evaporation is continued for 30min to form amorphous WO 3-x The electrochromic layer 11 is provided.

[0031] The temperature inside the vacuum tube furnace is raised until the temperature at the center of the vacuum tube furnace is 450°C, and then the layer group 12 is placed at the center of the vacuum tube furnace and heated for 30 minutes in the air atmosphere to perform air thermal oxidation. The layer group 12 after air thermal oxidation is taken out and cooled to room temperature to make the amorphous WO 3-x The electrochromic layer 11 is changed into high-purity monoclinic WO 3-x The nanocrystalline electrochromic layer 11, the high purity monoclinic WO 3-x The thickness of the nanocrystalline electrochromic layer 11 is 400 nm, thereby preparing a single-component dual-band electrochromic film 15 .

[0032] See also Figure 3 As shown, Figure 3 FIG. 1 shows a TEM (Transmission Electron Microscope) image of the second crystalline electrochromic layer 11 prepared by the preparation method of this embodiment. Figure 3 As shown in the left figure (a), the high-purity monoclinic WO 3-x The average grain size of nanocrystals is 10nm. Figure 3 As shown in the right figure (b), high-purity monoclinic WO can be prepared by the preparation method of this embodiment.3-x The nanocrystalline electrochromic layer 11 has only a monoclinic crystal phase and a lattice constant of 0.42 nm, wherein the lattice constant refers to the distance between two adjacent lattice points in a crystal.

[0033] See also Figure 4 As shown, Figure 4 The schematic diagram shows the average response time of coloring and the average response time of fading of the second crystalline electrochromic layer 11 prepared by the preparation method of this embodiment under visible light (wavelength range of 380nm~780nm) and near infrared light (wavelength range of 780nm~2500nm). Fading refers to the process in which the electrochromic layer 11 recovers from a certain color to transparent and colorless after applying an appropriate voltage. Coloring refers to the process in which the electrochromic layer 11 presents a certain color after applying an appropriate voltage. Among them, the response time is the time required for the change in transmittance to reach 90%. Figure 4 The horizontal axis is time and the vertical axis is transmittance. Figure 4 The process from 0s to 35s is the coloring process, and the transmittance gradually decreases with the change of time. The process from 35s to 70s is the fading process, and the transmittance gradually increases with the change of time. It can be seen that at a wavelength of 680nm, the average response time of coloring is 24.1s, and the average response time of fading is 16.3s. At a wavelength of 1000nm, the average response time of coloring is 15.9s, and the average response time of fading is 18.5s. The average response time of coloring and the average response time of fading are relatively short. In the related art, the average response time of coloring and the average response time of fading of some electrochromic layers are long, and the average response time of fading is particularly long. For example, amorphous WO prepared by a solution colloid method 3-x The average response time of coloring is 22s, the average response time of fading is 75s, and the average response time of triclinic WO 3-x The average response time of the nanocrystals to fade in the near-infrared region can even reach 105s. It can be seen that the second crystalline electrochromic layer 11 prepared by the preparation method of this embodiment has a shorter average response time for coloring and a significantly shorter average response time for fading than the electrochromic layer in the related art.

[0034] See also Figure 5 As shown, Figure 5 A schematic diagram showing the coloration efficiency (CE) value of the second crystalline electrochromic layer 11 prepared by the preparation method of this embodiment is shown. Coloration efficiency refers to the change in optical density caused by the amount of charge injected per unit area at a fixed wavelength, and is a performance indicator of the electrochromic layer 11. The higher the coloration efficiency, the stronger the light modulation capability. Figure 5The horizontal axis is the amount of charge injected per unit area (ΔQ), and the vertical axis is the change in optical density at a fixed wavelength (ΔOD). The coloring efficiency is expressed by the formula: It can be seen that at a wavelength of 680nm, the coloring efficiency value is 110.8cm 2 / C. At a wavelength of 1000nm, the coloring efficiency value is 284.2cm 2 Therefore, the second crystalline electrochromic layer 11 prepared by the preparation method of this embodiment has a strong light modulation capability in both visible light and near infrared light bands.

[0035] A comparative experiment was set up to obtain a comparative example single-component dual-band electrochromic film. The difference between the preparation method of the comparative experiment and the preparation method of this embodiment is that the comparative example single-component dual-band electrochromic film is not subjected to air thermal oxidation.

[0036] See also Figure 6 As shown, Figure 6 A schematic diagram showing the transmittance comparison between the single-component dual-band electrochromic film 15 prepared by the preparation method of this embodiment and the single-component dual-band electrochromic film of the comparative example under different potential control is shown. Figure 6 The horizontal axis is wavelength, and the vertical axis is transmittance. Among them, the left figure (a) is a single-component dual-band electrochromic film 15 prepared by the preparation method of this embodiment, and the right figure (b) is a single-component dual-band electrochromic film of the comparative example. It can be seen that the single-component dual-band electrochromic film 15 prepared by the preparation method of this embodiment can exhibit three photothermal regulation modes in the visible light band and near-infrared light band of 380nm~2500nm under different driving potentials, namely bright mode (visible light and near-infrared light are both highly transmitted), cold mode (visible light is highly transmitted and near-infrared light is blocked), and dark mode (visible light and near-infrared light are blocked). Figure 6 In the embodiment shown, the driving potential of the bright mode is 0.8V. The driving potential of the cold mode is -0.3V and -0.4V, and the driving potential of the dark mode is -0.8V. At a wavelength of 1300 nm, the difference in transmittance between the bright mode and the dark mode is as high as 95%, that is, it has an optical contrast of 95%, which exceeds the maximum infrared optical contrast of the existing single-component dual-band electrochromic film, and the optical contrast is high. Among them, the optical contrast refers to the maximum optical transmittance difference of the single-component dual-band electrochromic film at a specific wavelength. The single-component dual-band electrochromic film prepared in this way can show three light and heat control modes of bright, cold and dark under different driving potentials. And it can realize the partition adjustment of the visible light band and the near-infrared light band of 380nm~2500nm, and the optical adjustment range is large. And it has a very high optical contrast.

[0037] The comparative single-component dual-band electrochromic film prepared by the preparation method of the comparative experiment cannot achieve high visible light transmission while blocking near-infrared light, that is, it cannot achieve the cold mode in the control mode. And the optical contrast of the comparative single-component dual-band electrochromic film is relatively lower.

[0038] It can be seen that compared with the single-component dual-band electrochromic film of the comparative example, the single-component dual-band electrochromic film prepared by the preparation method of this embodiment achieves a significant improvement in the optical contrast of near-infrared light, and achieves an improvement in the partitioned modulation capability of the visible light and near-infrared light bands.

[0039] The preparation method of the single-component dual-band electrochromic film created by the present invention uses electron beam thermal evaporation to deposit the electrochromic material on one side of the substrate 10 to form a first crystalline electrochromic layer 11, so that the prepared electrochromic layer 11 is more uniform and firm. Afterwards, the layer group 12 formed by the first crystalline electrochromic layer 11 and the substrate 10 is subjected to air thermal oxidation, so that the size, microstructure and crystal system of the first crystalline electrochromic layer 11 can be adjusted to make the first crystalline electrochromic layer 11 become the second crystalline electrochromic layer 11. The air thermal oxidation method is used to make the preparation method of the second crystalline electrochromic layer 11 simpler. The obtained single-component dual-band electrochromic film 15 has an optical contrast of 95% at a wavelength of 1300nm, which exceeds the maximum infrared optical contrast of the existing single-component dual-band electrochromic film. It can also achieve zoned regulation of the visible light band and near-infrared light band from 380nm to 2500nm, with a large optical adjustment range and excellent zoned modulation effect of visible light and infrared light. It can achieve three independent photothermal regulation modes of bright, cold and dark under different driving potentials.

[0040] See again Figure 1 As shown, the single-component dual-band electrochromic film 15 is prepared by the above-mentioned preparation method. The single-component dual-band electrochromic film 15 includes a substrate 10 and an electrochromic layer 11 in a second crystalline state. In one embodiment, the thickness of the electrochromic layer in the second crystalline state is 100nm~1000nm. The second crystalline state is a high-purity monoclinic nanocrystal, and the average grain size of the nanocrystals in the high-purity monoclinic nanocrystals is 7nm~10nm. The substrate 10 includes a transparent conductive layer 13 and a substrate 14, and the electrochromic layer 11 in the second crystalline state is located on the side of the transparent conductive layer 13 away from the substrate 14.

[0041] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0042] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a single-component dual-band electrochromic film, characterized in that: include: Depositing the electrochromic material on one side of the substrate by electron beam thermal evaporation to form a first crystalline electrochromic layer, wherein the first crystalline electrochromic layer and the substrate together form a layer group; heating the layer group in the air atmosphere for a first set time at a set temperature to perform air thermal oxidation; The layer group after air thermal oxidation is taken out and cooled to room temperature, so that the first crystalline electrochromic layer is changed into the second crystalline electrochromic layer, thereby preparing the single-component dual-band electrochromic film.

2. The method for preparing a single-component dual-band electrochromic film according to claim 1, characterized in that: The method of depositing the electrochromic material on one side of the substrate by electron beam thermal evaporation to form a first crystalline electrochromic layer comprises: The electrochromic material and the substrate are placed inside a coating device, the interior of the coating device is evacuated to a set pressure, and the electrochromic material is electron beam evaporated on one side of the substrate at room temperature to form a first crystalline electrochromic layer.

3. The method for preparing a single-component dual-band electrochromic film according to claim 2, characterized in that: The set pressure is 2.5×10 -3 Pa~2.8×10 -3 Pa.

4. The method for preparing a single-component dual-band electrochromic film according to claim 2, characterized in that: The step of depositing the electrochromic material on one side of the substrate by electron beam evaporation to form a first crystalline electrochromic layer comprises: The electron beam is directed onto the electrochromic material, and the electron beam is adjusted so that the rate of evaporating the electrochromic material is maintained at a set rate, and the evaporation is continued for a second set time.

5. The method for preparing a single-component dual-band electrochromic film according to claim 4, characterized in that: The set rate is 0.1 nm / s to 0.5 nm / s; and / or The second set time is greater than or equal to 30 minutes.

6. The method for preparing a single-component dual-band electrochromic film according to claim 1, characterized in that: The set temperature is 400°C to 450°C; and / or The first set time is 30min~1000min; and / or The electrochromic material is tungsten trioxide.

7. A single-component dual-band electrochromic film, characterized in that: The single-component dual-band electrochromic film is prepared by the preparation method according to any one of claims 1 to 6, and comprises a substrate and a second crystalline electrochromic layer.

8. The single-component dual-band electrochromic film according to claim 7, characterized in that: The thickness of the electrochromic layer in the second crystalline state is 100 nm to 1000 nm.

9. The single-component dual-band electrochromic film according to claim 7, characterized in that: The second crystalline state is high-purity monoclinic nanocrystals; the average grain size of the nanocrystals in the high-purity monoclinic nanocrystals is 7nm-10nm.

10. The single-component dual-band electrochromic film according to claim 7, characterized in that: The substrate comprises a transparent conductive layer and a base plate, and the second crystalline electrochromic layer is located on a side of the transparent conductive layer away from the base plate.

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