WO 3-ⅹ Electrochromic thin film and method for preparing the same

Abstract

This invention provides a WO3 with controllable stoichiometry. 3‑x Electrochromic thin films and their preparation methods relate to the field of design and fabrication technology for optoelectronic functional thin film materials and devices. The thin films include transparent conductive glass substrates and WO3. 3‑x Layer, the WO 3‑x The layer contains several oxygen vacancies, x = 0~1, WO 3‑x The stoichiometric ratio of W and O elements in the layer is adjustable within the range of 1:(2-3). The preparation method includes step 1: depositing a WO3 thin film layer on a transparent conductive glass substrate; step 2: transferring the transparent conductive glass substrate with the WO3 thin film layer to a muffle furnace in a glove box, and filling the glove box with a specific proportion of mixed gas; step 3: heat-treating the WO3 thin film in the muffle furnace to obtain a WO3 layer with a controllable stoichiometric ratio. 3‑x Electrochromic thin film. This invention solves the problem that existing WO3 thin films cause an increase in the color-changing driving voltage, which is not conducive to the insertion and extraction of cations and affects the electrochromic performance of the material.

Description

Technical Field

[0001] This invention relates to the field of design and fabrication technology of optoelectronic functional thin film materials and devices, specifically a WO3 material with controllable stoichiometry. 3_ⅹ Electrochromic thin films and their preparation methods. Background Technology

[0002] With the increasing severity of energy consumption and environmental pollution, the development of energy-saving materials and devices has gradually become a global consensus. The efficient utilization of various energy sources and the effective avoidance of energy waste have thus attracted widespread attention from the scientific and industrial communities both domestically and internationally. In the field of energy-saving materials, electrochromism refers to the reversible change in color and transparency of certain materials under the influence of an applied alternating voltage or current, through the insertion and extraction of ions or electrons. Electrochromic materials exhibit a strong power-off memory effect, meaning that when the external power supply is cut off, the electrochromic material retains its color or fading state before the power was cut off. In other words, the color displayed by an electrochromic material does not require a continuous external power supply, thus electrochromic materials can significantly save energy. Compared to liquid crystal and suspended particle dimming, materials and devices based on electrochromic phenomena have advantages such as low driving voltage, continuously adjustable color, low energy consumption, and the ability to retain information even after power failure. They can achieve good energy-saving effects and have been widely used in fields such as smart windows, car rearview mirrors, goggles, and displays.

[0003] WO3 (tungsten trioxide) is one of the most commonly used cathode electrochromic materials in existing technologies, possessing advantages such as significant color changes, high light contrast, and fast response speed. Under applied voltage or current, thin-film WO3 undergoes ion and electron insertion and extraction, resulting in a reversible color transition between a colored state (blue) and a fading state (transparent), thus enabling reversible control of visible light transmittance. Therefore, WO3 thin films have received significant research attention and widespread application in related fields.

[0004] However, in practical applications, WO3 films with a W / O stoichiometric ratio of 1:3 are wide-bandgap semiconductors with very low conductivity, leading to an increase in the color-changing driving voltage. Furthermore, their dense structure and narrow pores hinder the insertion and extraction of cations, thus affecting the electrochromic performance of the material. For example, Chinese patent CN110673417A discloses a tungsten trioxide electrochromic capacitor bifunctional thin film material and its preparation method. This thin film material has a porous structure and a mixed micro-region crystalline structure containing tungsten trioxide crystal nuclei. However, this patent does not optimize or improve the low conductivity, dense structure, and narrow pores of tungsten trioxide, resulting in unsatisfactory electrochromic performance in practical applications. Summary of the Invention

[0005] The purpose of this invention is to provide a WO3 with a controllable stoichiometric ratio. 3_ⅹ Electrochromic thin films and their preparation methods are proposed to address the problem that existing WO3 thin films, being wide-bandgap semiconductors, have very low conductivity, dense structure, and narrow pores, which leads to increased color-changing driving voltage, hinders cation insertion and extraction, and affects the electrochromic performance of the material.

[0006] This invention is achieved using the following technical solution:

[0007] A controllable stoichiometric WO3 3-ⅹ Electrochromic thin films, including transparent conductive glass substrates and WO3. 3_ⅹ Layer, the WO 3_ⅹ The layer contains several oxygen vacancies, x = 0 to 1, WO 3-ⅹ The stoichiometric ratio of W and O elements in the layer is adjustable within the range of 1:(2-3). It should be noted that both the ranges "0-1" and "1:(2-3)" include decimal values.

[0008] In this invention, to improve the relatively low conductivity of traditional WO3 films, several oxygen vacancies are appropriately introduced to construct defective WO3 films with a stoichiometric ratio deviating from the original 1:3. 3-ⅹ Thin films. Specifically, the introduction of appropriate oxygen vacancies is equivalent to introducing impurity energy levels into the WO3 band gap, which can relatively increase the WO3 band gap. 3_ⅹ The conductivity of the base material can reduce the color-changing driving voltage; at the same time, the introduction of oxygen vacancies will make the microstructure of the film looser and the channels wider, which is conducive to the transport and diffusion of ions in the film, thereby improving the performance parameters such as the response speed and light modulation range of electrochromism.

[0009] Furthermore, the WO 3-ⅹ The thickness of the layer is 100nm~10μm, WO 3-ⅹ The optical transmittance of the layer is 40-95%. In this scheme, WO... 3-ⅹ The thickness of the layer was limited because, during electrochromism, if the thickness is too thin, the transmittance contrast between colored and faded states is too small; if the thickness is too thick, although the transmittance contrast between colored and faded states can be increased to some extent, the transmittance of the faded state will definitely be lower than that of the colored state. An excessively thick film would hinder light transmission. Therefore, it is necessary to limit the WO3 layer thickness. 3-ⅹ The thickness of the layer is limited to a reasonable range.

[0010] Furthermore, the transparent conductive glass substrate includes a glass substrate and a transparent conductive layer; wherein, the glass substrate is selected from either soda-lime glass or quartz glass, and the transparent conductive layer is selected from either indium tin oxide (ITO), tin oxide doped with fluorine (FTO), or zinc oxide doped with aluminum (AZO).

[0011] Furthermore, the WO 3-ⅹ The electrochromic film is transparent or light blue in color. 3-ⅹ The microstructure of the layer is a flat thin film, nanosheet, nanowire, or nanoparticle.

[0012] A controllable stoichiometric WO3 3-ⅹ A method for preparing electrochromic thin films, used to prepare WO3 with controllable stoichiometry as described above. 3-ⅹ An electrochromic thin film, comprising the following steps:

[0013] Step 1: Deposit a WO3 thin film layer on a transparent conductive glass substrate;

[0014] Step 2: Transfer the transparent conductive glass substrate with WO3 thin film layer grown on it to the glove box through the transition chamber and after 1 to 3 cycles of evacuation and inflation. Then place it in the muffle furnace in the glove box and fill the glove box with a specific ratio of mixed gas.

[0015] Step 3: Heat-treat the WO3 thin film in the muffle furnace to obtain WO3 with a controllable stoichiometric ratio. 3-ⅹ Electrochromic thin film.

[0016] In this invention, the enclosed environment of the glove box ensures that the WO3 film can be processed without interference from the external atmosphere. By controlling the atmosphere within the glove box through a specific ratio of mixed gases and performing heat treatment at a specific temperature and time, different amounts of lattice oxygen atoms can be released from the WO3 film as oxygen, thereby achieving a controllable W / O stoichiometric ratio for WO3. 3-ⅹ The synthesis of electrochromic thin films allows for the acquisition of films with excellent electrochromic properties. Among these, the obtained WO3... 3-ⅹ The specific value of x in electrochromic films is closely related to the atmosphere and heat treatment process conditions in the glove box (specifically, the higher the heat treatment temperature, the longer the heat treatment time, and the higher the inert gas content, the larger the x value). Therefore, by adjusting the atmosphere and heat treatment process conditions in the glove box, the x value can be adjusted. 3-ⅹ Continuous regulation of oxygen vacancy content in the layer can thus achieve control over WO3. 3_ⅹ By continuously controlling the conductivity, microstructure, and internal pores of electrochromic thin films, tungsten oxide thin film materials with different electrochromic properties can be obtained.

[0017] Furthermore, in step 1, the specific deposition method can be either a physical method or a chemical method. Physical methods include thermal evaporation, electron beam evaporation, magnetron sputtering, and pulsed laser deposition. Chemical methods include sol-gel method, hydrothermal method, and electrochemical deposition method.

[0018] Furthermore, in step 2, the mixed gas is a mixture of an inert gas and oxygen, wherein the inert gas is either nitrogen or argon.

[0019] Furthermore, the glove box is equipped with two independent air passages, which are used to fill in inert gas and oxygen respectively.

[0020] Furthermore, the gas path is an adjustable flow path, and the volume ratio of inert gas and oxygen is adjusted by regulating the flow rates of the two gas paths. Specifically, the flow rate of each gas path can be controlled by adjusting the main valve and pressure reducing valve at the gas cylinder connection. Compared with the traditional tube furnace heat treatment of tungsten oxide electrochromic films, the present invention uses a glove box, which provides a relatively static gas atmosphere, unlike the relatively fluid atmosphere in a tube furnace, which is not conducive to the stable heat treatment of the film. In addition, tube furnaces usually have only one gas path, making it difficult to fill with a mixed gas with continuously adjustable proportions, which is not conducive to the continuous control of oxygen vacancy content in the film. Furthermore, the quartz tube in the tube furnace is cylindrical and has limited usable internal space, which is not conducive to the one-time heat treatment of large areas and large batches of electrochromic films.

[0021] Furthermore, in step 3, the heating rate for heat treatment is 2–10 °C / min, the heating temperature range is 200–550 °C, and the heating time is 0.5–5 h; after the heating is completed, natural cooling is performed.

[0022] The beneficial effects achieved by this invention are:

[0023] This invention provides a WO3 with controllable stoichiometry. 3-ⅹ The preparation method of electrochromic thin films involves adjusting the specific ratio of inert gas and oxygen in a glove box, as well as the specific temperature and time of the heat treatment process, to synthesize WO3 with continuously controllable stoichiometry. 3_ⅹ Electrochromic film; WO 3_ⅹ Compared to existing WO3 films, electrochromic films have higher conductivity, a more porous microstructure, and wider pores, which can reduce the color-changing driving voltage, facilitate the transport and diffusion of ions in the film, improve electrochromic performance, and ensure the effective performance. Attached Figure Description

[0024] Figure 1 The WO prepared in Example 1 of this invention 3_ⅹ SEM image of the electrochromic thin film;

[0025] Figure 2 The WO prepared in Embodiment 2 of this invention 3-ⅹ SEM image of the electrochromic thin film;

[0026] Figure 3 The WO prepared in Example 3 of this invention 3-ⅹ SEM image of the electrochromic thin film;

[0027] Figure 4 The WO prepared in Example 4 of this invention 3-ⅹ SEM image of the electrochromic thin film;

[0028] Figure 5 These are the four types of WO3 obtained at different heat treatment temperatures in Examples 1-4 of this invention. 3-ⅹ XRD pattern of electrochromic thin film;

[0029] Figure 6 These are the four types of WO3 obtained at different heat treatment temperatures in Examples 1-4 of this invention. 3-ⅹ Transmission spectra of colored and decolored states of electrochromic thin films. Detailed Implementation

[0030] To clearly illustrate the solution in this invention, further explanation is provided below with reference to the accompanying drawings:

[0031] Example 1

[0032] This embodiment provides, in a first aspect, a WO3 with a controllable stoichiometry. 3-ⅹ The method for preparing an electrochromic thin film includes the following steps:

[0033] Step 1: Deposit a WO3 thin film layer on a transparent conductive glass substrate;

[0034] Step 1-1: Dissolve 0.1685g of sodium tungstate dihydrate (Na2WO4·2H2O) and 0.2101g of citric acid monohydrate (C6H8O7·H2O) in 20mL of deionized water and stir at room temperature until completely dissolved; then add 2.5mol / L hydrochloric acid dropwise to the above solution to adjust the pH to 1. After stirring evenly at room temperature, a transparent precursor solution is obtained.

[0035] Steps 1-2: Select fluorine-doped tin oxide (FTO) transparent conductive glass as the substrate, ultrasonically clean it in ethanol and deionized water for 30 minutes in sequence and dry it, and then place it in the lining of a hydrothermal reactor;

[0036] Steps 1-3: Transfer the transparent precursor solution into the liner of the hydrothermal reactor, and then tighten the hydrothermal reactor; place the hydrothermal reactor in a forced-air oven, set the heating rate to 5℃ / min, raise the temperature from room temperature to 90℃ and hold for 2 hours; then close the oven and wait for it to cool to room temperature, remove the conductive glass substrate from the hydrothermal reactor, rinse it three times with deionized water, and finally vacuum dry it at 60℃ for 1 hour to obtain the WO3 film;

[0037] Step 2: Transfer the WO3 film with a W / O stoichiometric ratio of 1:3 to the muffle furnace in the glove box, and fill the glove box with a mixture of argon and oxygen, wherein the flow rate ratio of argon to oxygen is 2:1.

[0038] Step 3: Heat-treat the WO3 film in the muffle furnace. Set the heating rate of the muffle furnace to 5℃ / min, raise it from room temperature to 250℃, hold it at that temperature for 2 hours, and then allow it to cool naturally. Finally, obtain WO3 with a controllable stoichiometric ratio. 3-ⅹ Electrochromic thin film.

[0039] This embodiment provides a controllable stoichiometric WO3 in a second aspect. 3-ⅹ The electrochromic thin film, prepared by the method described above, is a WO 3_ⅹ Electrochromic thin films include transparent conductive glass substrates and WO3. 3-ⅹ Layer, the WO 3-ⅹ The layer contains several oxygen vacancies, x = 0 to 1, WO 3-ⅹ The stoichiometric ratio of W and O elements in the layer is adjustable within the range of 1:(2–3). Specifically, WO... 3-ⅹ The layer thickness is 100nm~10μm, WO 3-ⅹ The optical transmittance of the layer is 40-95%; the transparent conductive glass substrate includes a glass substrate and a transparent conductive layer, wherein the glass substrate is selected from either soda-lime glass or quartz glass, and the transparent conductive layer is selected from fluorine-doped tin oxide (FTO); WO 3-ⅹ The electrochromic film is transparent or light blue in color; such as Figure 1 As shown, WO in this embodiment 3-ⅹ The microstructure of the layer is uniform nanosheets.

[0040] Example 2

[0041] This embodiment provides, in a first aspect, a WO3 with a controllable stoichiometry. 3-ⅹ The method for preparing an electrochromic thin film includes the following steps:

[0042] Step 1: Deposit a WO3 thin film layer on a transparent conductive glass substrate;

[0043] Step 1-1: Dissolve 0.1685g of sodium tungstate dihydrate (Na2WO4·2H2O) and 0.2101g of citric acid monohydrate (C6H8O7·H2O) in 20mL of deionized water and stir at room temperature until completely dissolved; then add 2.5mol / L hydrochloric acid dropwise to the above solution to adjust the pH to 1. After stirring evenly at room temperature, a transparent precursor solution is obtained.

[0044] Steps 1-2: Select fluorine-doped tin oxide (FTO) transparent conductive glass as the substrate, ultrasonically clean it in ethanol and deionized water for 30 minutes in sequence and dry it, and then place it in the lining of the hydrothermal reactor;

[0045] Steps 1-3: Transfer the transparent precursor solution into the liner of the hydrothermal reactor, and then tighten the hydrothermal reactor; place the hydrothermal reactor in a forced-air oven, set the heating rate to 5℃ / min, raise the temperature from room temperature to 90℃ and hold for 2 hours; then close the oven and wait for it to cool to room temperature, remove the conductive glass substrate from the hydrothermal reactor, rinse it three times with deionized water, and finally vacuum dry it at 60℃ for 1 hour to obtain the WO3 film;

[0046] Step 2: Transfer the WO3 film with a W / O stoichiometric ratio of 1:3 to the muffle furnace in the glove box, and fill the glove box with a mixture of argon and oxygen, wherein the flow rate ratio of argon to oxygen is 4:1.

[0047] Step 3: Heat-treat the WO3 film in the muffle furnace. Set the heating rate of the muffle furnace to 5℃ / min, raise it from room temperature to 300℃, hold it at that temperature for 1 hour, and then allow it to cool naturally. Finally, obtain WO3 with a controllable stoichiometric ratio. 3-ⅹ Electrochromic thin film.

[0048] This embodiment provides a controllable stoichiometric WO3 in a second aspect. 3-ⅹ The electrochromic thin film, prepared by the method described above, is a WO 3_ⅹ Electrochromic thin films include transparent conductive glass substrates and WO3. 3-ⅹ Layer, the WO 3-ⅹ The layer contains several oxygen vacancies, x = 0 to 1, WO 3-ⅹ The stoichiometric ratio of W and O elements in the layer is adjustable within the range of 1:(2–3). Specifically, WO... 3-ⅹ The thickness of the layer is 100nm~10μm, WO 3-ⅹ The optical transmittance of the layer is 40-95%; the transparent conductive glass substrate includes a glass substrate and a transparent conductive layer, wherein the glass substrate is selected from either soda-lime glass or quartz glass, and the transparent conductive layer is selected from fluorine-doped tin oxide (FTO); WO 3-ⅹ The electrochromic film is transparent or light blue in color; such as Figure 2As shown, WO in this embodiment 3-ⅹ The microstructure of the layer is also uniform nanosheet-like, which is not much different from the morphology presented in Example 1.

[0049] Example 3

[0050] This embodiment provides, in a first aspect, a WO3 with a controllable stoichiometry. 3-ⅹ The method for preparing an electrochromic thin film includes the following steps:

[0051] Step 1: Deposit a WO3 thin film layer on a transparent conductive glass substrate;

[0052] Step 1-1: Dissolve 0.1685g of sodium tungstate dihydrate (Na2WO4·2H2O) and 0.2101g of citric acid monohydrate (C6H8O7·H2O) in 20mL of deionized water and stir at room temperature until completely dissolved; then add 2.5mol / L hydrochloric acid dropwise to the above solution to adjust the pH to 1. After stirring evenly at room temperature, a transparent precursor solution is obtained.

[0053] Steps 1-2: Select fluorine-doped tin oxide (FTO) transparent conductive glass as the substrate, ultrasonically clean it in ethanol and deionized water for 30 minutes in sequence and dry it, and then place it in the lining of the hydrothermal reactor;

[0054] Steps 1-3: Transfer the transparent precursor solution into the liner of the hydrothermal reactor, and then tighten the hydrothermal reactor; place the hydrothermal reactor in a forced-air oven, set the heating rate to 5℃ / min, raise the temperature from room temperature to 90℃ and hold for 2 hours; then close the oven and wait for it to cool to room temperature, remove the conductive glass substrate from the hydrothermal reactor, rinse it three times with deionized water, and finally vacuum dry it at 60℃ for 1 hour to obtain the WO3 film;

[0055] Step 2: Transfer the WO3 film with a W / O stoichiometric ratio of 1:3 to the muffle furnace in the glove box, and fill the glove box with a mixture of argon and oxygen, wherein the flow rate ratio of argon to oxygen is 6:1.

[0056] Step 3: Heat-treat the WO3 film in the muffle furnace. Set the heating rate of the muffle furnace to 5℃ / min, raise it from room temperature to 350℃, hold it at that temperature for 1 hour, and then allow it to cool naturally. Finally, obtain WO3 with a controllable stoichiometric ratio. 3-ⅹ Electrochromic thin film.

[0057] This embodiment provides a controllable stoichiometric WO3 in a second aspect. 3-ⅹ The electrochromic thin film, prepared by the method described above, is a WO 3-ⅹ Electrochromic thin films include transparent conductive glass substrates and WO3. 3-ⅹ Layer, the WO 3-ⅹThe layer contains several oxygen vacancies, x = 0 to 1, WO 3-ⅹ The stoichiometric ratio of W and O elements in the layer is adjustable within the range of 1:(2–3). Specifically, WO... 3-ⅹ The thickness of the layer is 100nm~10μm, WO 3_ⅹ The optical transmittance of the layer is 40-95%; the transparent conductive glass substrate includes a glass substrate and a transparent conductive layer, wherein the glass substrate is selected from either soda-lime glass or quartz glass, and the transparent conductive layer is selected from fluorine-doped tin oxide (FTO); WO 3-ⅹ The electrochromic film is transparent or light blue in color; such as Figure 3 As shown, in this embodiment, based on Embodiment 1 and Embodiment 2, due to the increase in temperature conditions during the heat treatment process, the nanosheets will continuously grow and connect, resulting in the formation of nanosheet aggregates in some areas of the film.

[0058] Example 4

[0059] This embodiment provides, in a first aspect, a WO3 with a controllable stoichiometry. 3-ⅹ The method for preparing an electrochromic thin film includes the following steps:

[0060] Step 1: Deposit a WO3 thin film layer on a transparent conductive glass substrate;

[0061] Step 1-1: Dissolve 0.1685g of sodium tungstate dihydrate (Na2WO4·2H2O) and 0.2101g of citric acid monohydrate (C6H8O7·H2O) in 20mL of deionized water and stir at room temperature until completely dissolved; then add 2.5mol / L hydrochloric acid dropwise to the above solution to adjust the pH to 1. After stirring evenly at room temperature, a transparent precursor solution is obtained.

[0062] Steps 1-2: Select fluorine-doped tin oxide (FTO) transparent conductive glass as the substrate, ultrasonically clean it in ethanol and deionized water for 30 minutes in sequence and dry it, and then place it in the lining of the hydrothermal reactor;

[0063] Steps 1-3: Transfer the transparent precursor solution into the liner of the hydrothermal reactor, and then tighten the hydrothermal reactor; place the hydrothermal reactor in a forced-air oven, set the heating rate to 5℃ / min, raise the temperature from room temperature to 90℃ and hold for 2 hours; then close the oven and wait for it to cool to room temperature, remove the conductive glass substrate from the hydrothermal reactor, rinse it three times with deionized water, and finally vacuum dry it at 60℃ for 1 hour to obtain the WO3 film;

[0064] Step 2: Transfer the WO3 film with a W / O stoichiometric ratio of 1:3 to the muffle furnace in the glove box, and fill the glove box with a mixture of argon and oxygen, wherein the flow rate ratio of argon to oxygen is 8:1.

[0065] Step 3: Heat-treat the WO3 film in the muffle furnace. Set the heating rate of the muffle furnace to 5℃ / min, raise it from room temperature to 400℃, hold it at that temperature for 0.5h, and then allow it to cool naturally. Finally, obtain WO3 with a controllable stoichiometric ratio. 3-ⅹ Electrochromic thin film.

[0066] This embodiment provides a controllable stoichiometric WO3 in a second aspect. 3-ⅹ The electrochromic thin film, prepared by the method described above, is a WO 3_ⅹ Electrochromic thin films include transparent conductive glass substrates and WO3. 3-ⅹ Layer, the WO 3-ⅹ The layer contains several oxygen vacancies, x = 0 to 1, WO 3-ⅹ The stoichiometric ratio of W and O elements in the layer is adjustable within the range of 1:(2–3). Specifically, WO... 3-ⅹ The thickness of the layer is 100nm~10μm, WO 3-ⅹ The optical transmittance of the layer is 40-95%; the transparent conductive glass substrate includes a glass substrate and a transparent conductive layer, wherein the glass substrate is selected from either soda-lime glass or quartz glass, and the transparent conductive layer is selected from fluorine-doped tin oxide (FTO); WO 3-ⅹ The electrochromic film is transparent or light blue in color; such as Figure 3 As shown in this embodiment, based on Example 3, due to the continued increase in temperature during the heat treatment process, the nanosheets will continue to grow and merge, thereby increasing the size of the nanosheets.

[0067] Figure 5 These are the four types of WO3 obtained at different heat treatment temperatures in Examples 1-4 of this invention. 3-ⅹ The XRD pattern of the electrochromic thin film shows that, with increasing argon content and heat treatment temperature, no other impurity peaks are generated except for the characteristic peak of tungsten oxide around 23°C, proving that the heat treatment in the glove box did not produce any other impurity phases. Furthermore, this characteristic peak gradually intensifies with increasing temperature, while its full width at half maximum (FWHM) gradually decreases, indicating enhanced crystallinity. With increasing argon content and temperature, this characteristic peak gradually shifts to the left, indicating an increase in the number of oxygen vacancies formed. The loss of lattice oxygen enlarges the interstitial spaces in the tungsten oxide structure, widening the channels for ion insertion and extraction, which facilitates rapid transport and diffusion of ions and electrons, thereby improving the electrochromic performance.

[0068] Figure 6 These are the four types of WO3 obtained at different heat treatment temperatures in Examples 1-4 of this invention. 3-ⅹThe transmission spectra of the colored and faded states of the electrochromic thin film show that, with the increase of argon gas and temperature, the oxygen vacancy content gradually increases, and some W atoms exhibit a +5 valence, which reduces the transmittance of the initial state of the film. However, the introduction of an appropriate amount of oxygen vacancies improves the conductivity of the tungsten oxide-based thin film, which is beneficial to the transport and diffusion of ions and electrons. At a heat treatment temperature of 250–350 °C, the contrast between the colored and faded states of the film at 680 nm can reach ~40%.

[0069] In summary, this invention provides a WO3 with a controllable stoichiometric ratio. 3-ⅹ The preparation method of electrochromic thin films involves adjusting the specific ratio of inert gas and oxygen in a glove box, as well as the specific temperature and time of the heat treatment process, to synthesize WO3 with continuously controllable stoichiometry. 3-ⅹ An electrochromic thin film is obtained, thereby achieving the purpose of controlling the electrochromic properties of tungsten oxide thin films. The preparation method is simple to operate, has a wide range of applications, and can process WO3-x thin films in batches in a single operation; the WO3-x... 3-ⅹ Compared to existing WO3 films, electrochromic films have higher conductivity, a more porous microstructure, and wider pores, which can reduce the color-changing driving voltage, facilitate the transport and diffusion of ions in the film, improve electrochromic performance, and ensure the effective performance.

[0070] Of course, the above description is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the embodiments of the present invention. The present invention is also not limited to the above examples, and all equivalent changes and improvements made by those skilled in the art within the scope of the present invention should fall within the patent coverage of the present invention.

Claims

1. A controllable stoichiometry ratio of An electrochromic film, characterized in that: comprising a transparent conductive glass substrate and layer, said layer containing several oxygen vacancies, , in the layer elements and the stoichiometric ratio of the elements is adjustable in the range of 1: (2-3); The The thickness of the layer is 100 nm to 10 μm. The The layer is formed by depositing on a transparent conductive glass substrate. The thin film layer is obtained by heat treatment; before the heat treatment, it passes through the transition chamber of a glove box and undergoes 1 to 3 cycles of evacuation and inflation to grow the film. The transparent conductive glass substrate of the thin film layer is transferred into the glove box; The heat treatment occurs in a muffle furnace of a glove box, the glove box is filled with mixed gas with a specific ratio; the mixed gas is a mixture of inert gas and oxygen; the glove box is internally provided with two independent gas paths, the two gas paths are respectively used for filling inert gas and oxygen; the gas path is a flow adjustable gas path, the volume ratio of the inert gas and the oxygen is adjusted by adjusting the flow of the two gas paths; The heating rate of the heat treatment is 2-10 DEG C / min, the heating temperature range is 200-550 DEG C, and the heating time is 0.5-5 h; after heating, natural cooling is carried out.

2. The controllable stoichiometry ratio of claim 1, An electrochromic film, characterized by: The The optical transmittance of the layer is 40-95%.

3. The controllable stoichiometry ratio of claim 1 An electrochromic film, characterized by: The transparent conductive glass substrate comprises a glass substrate and a transparent conductive layer; wherein the glass substrate is selected from one of soda lime glass or quartz glass, and the transparent conductive layer is selected from one of tin-doped indium oxide, fluorine-doped tin oxide and aluminum-doped zinc oxide.

4. The controllable stoichiometry ratio of claim 1 An electrochromic film characterized by: The The color of the electrochromic film is transparent or light blue, The micro-morphology of the layer is a flat film or nanosheet or nanowire or nanoparticle.

5. A controllable stoichiometry electrochromic film according to any one of claims 1 to 4, wherein the film is a controllable stoichiometry electrochromic film according to any one of claims 1 to 4. A method for preparing an electrochromic film, for preparing a controllable stoichiometry electrochromic film according to any one of claims 1 to 4. An electrochromic film according to any one of claims 1 to 4, characterized in that, The method comprises the following steps: Step 1 : Depositing a thin film layer on a transparent conductive glass substrate thin film layer; Step 2: The transparent conductive glass substrate with thin film layers is transferred into the muffle furnace of the glove box, and a mixed gas with a specific ratio is filled into the glove box. Step 2: The transparent conductive glass substrate with thin film layers is transferred into the muffle furnace of the glove box, and a mixed gas with a specific ratio is filled into the glove box. Step 3: Heat treatment of the thin film in a muffle furnace to obtain an electrochromic thin film with controllable stoichiometry. Step 3: Heat treatment of the thin film in a muffle furnace to obtain an electrochromic thin film with controllable stoichiometry. Step 3: Heat treatment of the thin film in a muffle furnace to obtain an 6. The controllable stoichiometry ratio of claim 5, wherein the ratio of the first and second reactants is controlled by the ratio of the first and second reactants in the first and second reservoirs. The method for producing an electrochromic film is characterized by comprising: In step 1, the specific method of deposition can be selected from one of thermal evaporation, electron beam evaporation, magnetron sputtering, pulsed laser deposition, sol-gel method, hydrothermal method and electrochemical deposition.

7. The controllable stoichiometry ratio of claim 5 Process for the preparation of an electrochromic film, characterized in that: In step 2, the mixed gas is a mixture of inert gas and oxygen, wherein the inert gas is one of nitrogen or argon.

8. The controllable stoichiometry ratio of claim 7, Process for the preparation of an electrochromic film, characterized in that: The glove box is internally provided with two independent gas paths, the two gas paths are respectively used for filling inert gas and oxygen.

9. The controllable stoichiometry ratio of claim 8 Process for the preparation of an electrochromic film, characterized in that: The gas path is a flow adjustable gas path, the volume ratio of the inert gas and the oxygen is adjusted by adjusting the flow of the two gas paths.

10. The controllable stoichiometry ratio of claim 5 Process for the preparation of an electrochromic film, characterized in that: In step 3, the heating rate of the heat treatment is 2-10 DEG C / min, the heating temperature range is 200-550 DEG C, and the heating time is 0.5-5 h; after heating, natural cooling is carried out.

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