Electrochromic film material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of functional film materials, and particularly relates to an electrochromic film material and a preparation method and application thereof. The thin film material prepared by the invention comprises a composite metal oxide with the thickness of 180-220 nm as a second functional layer and a metal tungsten film with the thickness of 8-12 nm as a first functional layer, and the optical thin film has optical transmission and reflection working modes and can present different colors on two sides in an initial state; the optical thin film has high electrochromism performance, the rapid reversible change from sky blue to dark purple can be macroscopically achieved from the front face, the rapid reversible change from light red to dark brown can be macroscopically achieved from the back face, the coloring efficiency is 44.1-51.0 cm < 2 > / C, the cycle index exceeds 1000 circles and is hardly attenuated, and the optical thin film is simple in structure and low in cost. The preparation method is easy and has a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of functional thin film materials, and in particular relates to an electrochromic thin film material and a preparation method and application thereof. Background Art

[0002] The information disclosed in the background of the invention is only intended to enhance the understanding of the overall background of the invention and should not be necessarily regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Electrochromic materials have attracted much attention due to their tunable and reversible modulation of optical properties (transmittance, absorbance, or reflectance) under low-voltage driving and are promising materials in many aspects.

[0004] Tungsten Oxide (WO 3 ) is an n-type semiconductor and is a promising material due to its high transparency, good color rendering efficiency and low response time. 3 The film also has many disadvantages, such as poor cycling stability and the ability to only transform from a transparent state to a blue state.

[0005] Therefore, poor cycling stability and color diversity modulation have been the main problems of WO 3 Problems that need to be solved in the field of electrochromic applications. Summary of the invention

[0006] In view of the needs of the prior art, the purpose of the present invention is to provide an electrochromic thin film material and its preparation method and application. The electrochromic thin film material prepared by the present invention has the advantages of both reflection and transmission properties, as well as color diversity, excellent cycle stability, high coloring efficiency, etc.

[0007] Specifically, the present invention provides the following technical solutions: In a first aspect of the present invention, an electrochromic thin film material is provided. The electrochromic thin film material is a multilayer composite structure, comprising a conductive substrate layer, a first functional layer, and a second functional layer arranged in sequence from bottom to top; the first functional layer is a metal layer, and the metal material in the metal layer includes tungsten; the second functional layer is a composite metal oxide layer, and the oxide in the composite metal oxide layer is selected from a composite of tungsten oxide and titanium oxide; The thickness of the first functional layer is 8-12 nm; the thickness of the second functional layer is 180-220 nm.

[0008] Preferably, the thickness of the first functional layer is 10 nm; the thickness of the second functional layer is 200 nm.

[0009] Preferably, the conductive substrate layer is one of commercial ITO conductive glass or FTO conductive glass.

[0010] The second aspect of the present invention provides a method for preparing the above-mentioned electrochromic thin film material, comprising the following steps: S1, depositing metal tungsten on the surface of the pretreated conductive substrate by magnetron sputtering to obtain a first functional layer; S2. Depositing metal tungsten and metal oxide on the surface of the first functional layer by magnetron sputtering to obtain a second functional layer.

[0011] Preferably, in step S1, the specific operation of the pretreatment is: ultrasonically cleaning the conductive substrate with acetone, ethanol and deionized water for 20 to 30 minutes respectively, and then drying it in a vacuum oven.

[0012] Preferably, in step S1, the target material in the magnetron sputtering method is metal tungsten, which is placed in a single DC target, the sputtering power is 100 W, the sputtering gas pressure is 0.2~0.5 Pa, the sputtering time is 1~5 min, the working atmosphere is argon, and the gas flow rate of the argon is 20~60 sccm.

[0013] Preferably, in step S2, the target materials in the magnetron sputtering method are metal tungsten and titanium oxide, the metal tungsten is placed in a DC target, and the sputtering power is 100 W; the titanium oxide is placed in a RF target, and the sputtering power is 50-100 W.

[0014] Preferably, in step S2, the sputtering pressure in the magnetron sputtering method is 0.3-0.6 Pa, the sputtering time is 15-30 min, the working atmosphere is a mixed atmosphere of argon and oxygen, and the gas flow rates of argon and oxygen are 30-60 sccm and 10-20 sccm, respectively.

[0015] The third aspect of the present invention provides a use of the electrochromic thin film material described in the first aspect in an electrochromic device.

[0016] Preferably, the light-transmitting color-changing effect of the electrochromic thin film material in the electrochromic device has the following performance characteristics: In reflective mode, the two sides appear different colors, and in transmissive mode, they are light-transmissive; The front side can achieve a reversible change from sky blue to dark purple when a voltage of -0.5V to +0.5V is applied; The back side can achieve a reversible change from light red to dark brown when a voltage of -0.5V to +0.5V is applied; The coloring efficiency is 44.1~51.0 cm² / C.

[0017] The beneficial effects achieved by one or more of the above technical solutions of the present invention are as follows: (1) Compared with the prior art, the electrochromic thin film material prepared by the present invention has both reflection and transmission properties. The prepared optical film has different colors when observed from both sides of the film. By applying voltage to the film, the color of both sides of the optical film can be changed (during the color change process, the reflection spectrum shows an obvious red shift at the peak position, from 483 nm to 419 nm, thereby achieving a larger modulation range (amplitude reaches 64 nm).

[0018] (2) The optical thin film structure provided by the present invention has a simple preparation process and low cost. By regulating the power of the RF target and the thickness of the functional layer during magnetron sputtering, its color, reflectivity and transmittance can be effectively controlled, and the cyclic stability of the material can be improved. It has broad application prospects in the optoelectronic field.

[0019] (3) Compared with a single deposited second functional layer, the thin film material prepared by the present invention has a semi-reflective and semi-transmissive property. This is based on the presence of a thinner first functional layer of metal (with partial reflection properties), which forms an ultra-compact asymmetric Fabry-Perot cavity, and can achieve nanocavity resonance in the reflection spectrum, so that the thin film prepared by the present invention has structural color; Compared with the single deposition of tungsten oxide on the second functional layer, the thin film material prepared by the present invention has a more obvious refractive index change after being doped with titanium dioxide. In other words, for the doped sample, as the voltage is applied, the refractive index of the film changes more significantly. Therefore, the thin film material prepared by the present invention has a richer variety of color changes and thus has better electrochromic properties.

[0020] (4) The present invention uses a dual-target setting. Dual-target co-sputtering can independently adjust the sputtering power of the two targets to accurately control the ratio of the two components in the deposited film, thereby achieving fine control of the chemical composition of the film. The ratio of the two components can be flexibly adjusted according to actual needs to obtain optimal performance. During dual-target co-sputtering, the sputtered particles of the two targets are more fully mixed in space, which can effectively improve the uniformity of the film composition along the film thickness direction and the plane direction, making the overall performance of the film more uniform and stable. The ratio of doped atoms in a single doped target is fixed when the target material is prepared, and it is difficult to flexibly change it during the sputtering process. When a single doped target is sputtered, the uneven sputtering of the target surface may cause differences in the spatial distribution of the film components.

[0021] (5) The fast-response and high-cycle stability electrochromic film prepared by the present invention can be stably cycled (one cycle is one cycle for each coloring and fading) for more than 1,000 times. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0023] Figure 1 It is a schematic diagram of the structure of an embodiment of the present invention; wherein 1-conductive substrate layer, 2-metal layer, 3-metal oxide layer; Figure 2 is a surface morphology diagram of the thin film material in Example 1 of the present invention; Figure 3 is a color diagram of the thin film material under different voltages in Example 1 of the present invention; Figure 4 is a transmission spectrum diagram of the thin film material in Example 1 of the present invention at different voltages; Figure 5 is a reflection spectrum diagram of the thin film material in Example 1 of the present invention under different voltages; Figure 6 This is a graph showing the electrochromic coloring efficiency of the thin film material in Example 1 of the present invention; Figure 7 This is a graph of the electrochromic stability of the thin film material in Example 1 of the present invention; Figure 8 This is a graph showing the electrochromic coloring efficiency of the thin film material in Example 2 of the present invention; Fig. 9 This is a graph showing the electrochromic coloring efficiency of the thin film material in Example 3 of the present invention; Fig.10 This is a graph showing the electrochromic coloring efficiency of the thin film material in Example 4 of the present invention; Fig.11 This is a graph showing the electrochromic coloring efficiency of the thin film material in Comparative Example 1 of the present invention; Fig.12 is a color diagram of the thin film material under different voltages in Example 2 of the present invention; Fig.13 is a color diagram of the thin film material under different voltages in Example 3 of the present invention; Fig.14 is a color diagram of the thin film material under different voltages in Example 4 of the present invention; Fig.15 It is a color diagram of the thin film material under different voltages in Comparative Example 1 of the present invention; Fig.16 This is a graph showing the electrochromic stability of the thin film material in Comparative Example 1 of the present invention; Fig.17 It is a color diagram of the thin film material under different voltages in Comparative Example 2 of the present invention; Fig.18It is a color diagram of the thin film material under different voltages in Comparative Example 3 of the present invention; Fig.19 This is a graph of the electrochromic stability of the thin film material in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0024] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0025] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0026] Embodiment 1: This embodiment provides an electrochromic thin film material and a preparation method thereof, comprising the following steps: S1. The ITO conductive glass was ultrasonically cleaned with acetone, ethanol and deionized water for 15 min respectively, and then dried in a vacuum oven; S2. Using a single DC target, with metal tungsten as the target material, only argon gas is introduced into the vacuum chamber, and sputtered metal is deposited on the surface of the ITO conductive glass as the first functional layer (the thickness value is set to 10 nm). During the DC deposition sputtering process, the gas flow rate of argon gas is 20 sccm, the sputtering power is 100 W, the sputtering pressure is 0.2 Pa, and the sputtering time is 2 min; S3. Using dual targets (the DC target is used to place metal tungsten and the RF target is used to place titanium dioxide), oxygen and argon are introduced into the vacuum chamber, and sputtering is performed on the tungsten metal to obtain a composite metal oxide layer as the second functional layer (the thickness value is set to 200 nm). During the sputtering process, the gas flow rate of argon is 30 sccm, the gas flow rate of oxygen is 10 sccm, the DC target power is 100 W, the RF target power is 90 W, the sputtering pressure is 0.3 Pa, and the sputtering time is 20 min, thereby obtaining a titanium-doped tungsten oxide electrochromic film.

[0027] Embodiment 2: This embodiment provides an electrochromic thin film material and a preparation method thereof, comprising the following steps: S1. The ITO conductive glass was ultrasonically cleaned with acetone, ethanol and deionized water for 15 min respectively, and then dried in a vacuum oven; S2. Using a single DC target, with metal tungsten as the target material, only argon gas is introduced into the vacuum chamber, and sputtered metal is deposited on the surface of the ITO conductive glass as the first functional layer (the thickness value is set to 10 nm). During the DC deposition sputtering process, the gas flow rate of argon gas is 20 sccm, the sputtering power is 100 W, the sputtering pressure is 0.2 Pa, and the sputtering time is 2 min; S3. Using dual targets (the DC target is used to place metal tungsten and the RF target is used to place titanium oxide), oxygen and argon are introduced into the vacuum chamber, and sputtering is performed on the tungsten metal to obtain a composite metal oxide layer as the second functional layer (the thickness value is set to 200nm). During the sputtering process, the gas flow rate of argon is 30 sccm, the gas flow rate of oxygen is 10 sccm, the DC target power is 100 W, the RF target power is 80 W, the sputtering pressure is 0.3 Pa, and the sputtering time is 20 min, thereby obtaining a titanium-doped tungsten oxide electrochromic film.

[0028] The difference between the preparation method of this embodiment and that of Embodiment 1 is that in step S3, the RF target power is 80 W.

[0029] Embodiment 3: This embodiment provides an electrochromic thin film material and a preparation method thereof, comprising the following steps: S1. The ITO conductive glass was ultrasonically cleaned with acetone, ethanol and deionized water for 15 min respectively, and then dried in a vacuum oven; S2. Using a single DC target, with metal tungsten as the target material, only argon gas is introduced into the vacuum chamber, and sputtered metal is deposited on the surface of the ITO conductive glass as the first functional layer (the thickness value is set to 10 nm). During the DC deposition sputtering process, the gas flow rate of argon gas is 20 sccm, the sputtering power is 100 W, the sputtering pressure is 0.2 Pa, and the sputtering time is 2 min; S3. Using dual targets (the DC target is used to place metal tungsten and the RF target is used to place titanium oxide), oxygen and argon are introduced into the vacuum chamber, and sputtering is performed on the tungsten metal to obtain a composite metal oxide layer as the second functional layer (the thickness value is set to 200nm). During the sputtering process, the gas flow rate of argon is 30 sccm, the gas flow rate of oxygen is 10 sccm, the DC target power is 100 W, the RF target power is 70 W, the sputtering pressure is 0.3 Pa, and the sputtering time is 20 min, thereby obtaining a titanium-doped tungsten oxide electrochromic film.

[0030] The difference between the preparation method of this embodiment and that of Embodiment 1 is that in step S3, the RF target power is 70 W.

[0031] Embodiment 4: This embodiment provides an electrochromic thin film material and a preparation method thereof, comprising the following steps: S1. The ITO conductive glass was ultrasonically cleaned with acetone, ethanol and deionized water for 15 min respectively, and then dried in a vacuum oven; S2. Using a single DC target, with metal tungsten as the target material, only argon gas is introduced into the vacuum chamber, and sputtered metal is deposited on the surface of the ITO conductive glass as the first functional layer (the thickness value is set to 10 nm). During the DC deposition sputtering process, the gas flow rate of argon gas is 20 sccm, the sputtering power is 100 W, the sputtering pressure is 0.2 Pa, and the sputtering time is 2 min; S3. Using dual targets (the DC target is used to place metal tungsten and the RF target is used to place titanium oxide), oxygen and argon are introduced into the vacuum chamber, and sputtering is performed on the tungsten metal to obtain a composite metal oxide layer as the second functional layer (the thickness value is set to 200nm). During the sputtering process, the gas flow rate of argon is 30 sccm, the gas flow rate of oxygen is 10 sccm, the DC target power is 100 W, the RF target power is 100 W, the sputtering pressure is 0.3 Pa, and the sputtering time is 20 min, thereby obtaining a titanium-doped tungsten oxide electrochromic film.

[0032] The difference between the preparation method of this embodiment and that of Embodiment 1 is that in step S3, the RF target power is 100 W.

[0033] Comparative Example 1: This comparative example provides an electrochromic thin film material and a preparation method thereof, comprising the following steps: S1. The ITO conductive glass was ultrasonically cleaned with acetone, ethanol and deionized water for 15 min respectively, and then dried in a vacuum oven; S2, using a single DC target, with metal tungsten as the target material, and only argon gas in the vacuum chamber, sputtering metal is deposited on the surface of the ITO conductive glass as the first functional layer. During the DC deposition sputtering process, the gas flow rate of argon gas is 20 sccm, the sputtering power is 100 W, the sputtering pressure is 0.2 Pa, and the sputtering time is 2 min; S3, single DC target, with metal tungsten as the target material, oxygen and argon are introduced into the vacuum chamber, and sputtering is performed on the tungsten metal to obtain a single metal oxide layer as the second functional layer. During the sputtering process, the gas flow rate of argon is 30 sccm, the gas flow rate of oxygen is 10 sccm, the DC target power is 100 W, and the sputtering time is 20 min, thereby obtaining a tungsten oxide electrochromic film.

[0034] The difference between the preparation method of comparative example 1 and embodiment 1 is that in step S3, only a single DC target is used to prepare a single tungsten oxide film.

[0035] Comparative Example 2: This comparative example provides an electrochromic thin film material and a preparation method thereof, comprising the following steps: S1. The ITO conductive glass was ultrasonically cleaned with acetone, ethanol and deionized water for 15 min respectively, and then dried in a vacuum oven; S2. Using dual targets (a DC target for placing metal tungsten and an RF target for placing titanium oxide), oxygen and argon are introduced into the vacuum chamber, and sputtering is performed on the ITO conductive glass to obtain a composite metal oxide layer. During the sputtering process, the gas flow rate of argon is 30 sccm, the gas flow rate of oxygen is 10 sccm, the DC target power is 100 W, the RF target power is 100 W, the sputtering pressure is 0.3 Pa, and the sputtering time is 20 min, thereby obtaining a composite metal oxide electrochromic film.

[0036] The preparation method of Comparative Example 2 is different from that of Example 1 in that no metal tungsten film is deposited.

[0037] Comparative Example 3: This comparative example provides an electrochromic thin film material and a preparation method thereof, comprising the following steps: S1. The ITO conductive glass was ultrasonically cleaned with acetone, ethanol and deionized water for 15 min respectively, and then dried in a vacuum oven; S2. Using a single DC target, with metal tungsten as the target material, and only argon gas in the vacuum chamber, sputtered metal was deposited on the surface of the ITO conductive glass as the first functional layer (the thickness value was set to 100 nm). During the DC deposition sputtering process, the gas flow rate of argon gas was 20 sccm, the sputtering power was 100 W, the sputtering pressure was 0.2 Pa, and the sputtering time was 2 min; S3. Using dual targets (the DC target is used to place metal tungsten and the RF target is used to place titanium dioxide), oxygen and argon are introduced into the vacuum chamber, and sputtering is performed on the tungsten metal to obtain a composite metal oxide layer as the second functional layer (the thickness value is set to 200 nm). During the sputtering process, the gas flow rate of argon is 30 sccm, the gas flow rate of oxygen is 10 sccm, the DC target power is 100 W, the RF target power is 90 W, and the sputtering time is 20 min, thereby obtaining a titanium-doped tungsten oxide electrochromic film.

[0038] Test Example 1: This test example tests the electrochemical performance of Examples 1 to 4 and Comparative Examples 1 to 3. Experimental process: The obtained electrochromic functional thin film material is used as the working electrode, the silver / silver chloride electrode is used as the reference electrode, and the platinum electrode is used as the counter electrode. An electrochemical workstation is used for detection. An Avantis fiber optic spectrometer is used to perform transmission spectrum and reflection spectrum analysis on the obtained electrochromic functional thin film samples.

[0039] For Example 1: Using the constant potential polarization method, voltages of -0.1, -0.2, -0.3, -0.4, -0.5 and +0.5 V were applied to the electrochromic functional film sample prepared in Example 1, and it was observed that the color of both sides of the film material changed.

[0040] During the color change process, the transmittance spectrum of the sample front side is as follows Figure 4 As shown, with the applied voltage of -0.1, -0.2, -0.3, -0.4, and -0.5 V, the transmittance of the prepared titanium-doped tungsten oxide electrochromic thin film material gradually decreases, and the transmittance modulation amplitude of the prepared titanium-doped tungsten oxide electrochromic thin film material at 600 nm is 53.7%.

[0041] During the color change process, the reflectance spectrum of the front side of the sample is as follows: Figure 5 As shown in the figure, with the applied voltage of -0.1, -0.2, -0.3, -0.4, and -0.5 V, the reflection peak of the prepared titanium-doped tungsten oxide electrochromic thin film material gradually moves to the short-wave direction, from 483 nm to 419 nm, thereby achieving a larger modulation range (amplitude reaches 64 nm), and the color of the corresponding film changes, which is consistent with the front color photo of the real object. Figure 3 correspond.

[0042] The corresponding real object front and back color photos such as Figure 3 As shown, when observed from the front: applying voltages of -0.1, -0.2, -0.3, -0.4, and -0.5 V, the sample color changes from the initial blue to dark blue, purple, dark purple, brown, and other colors. When the applied voltage changes to +0.5 V, the sample color returns to the initial blue state, and the reflection modulation amplitude at 480 nm can reach 42%; when observed from the back: applying voltages of -0.1, -0.2, -0.3, -0.4, and -0.5 V, the sample color changes from the initial red to brown and then to brown. When the applied voltage changes to +0.5 V, the sample color returns to the initial red state. The sample shows a rich variety of color variations.

[0043] The electrochromic coloring efficiency of the prepared electrochromic functional film samples was tested, and the electrochromic coloring efficiency (CE) was calculated as follows: ; Where ΔQ is the amount of charge inserted or extracted per unit area of ​​electrochromic material, ΔOD is the change in optical density, Tb is the transmittance in the bleached state, and Tc is the transmittance in the colored state. CE can be evaluated by the slope of the ΔOD vs. ΔQ graph. The electrochromic coloring efficiency test results of the electrochromic functional film samples are shown in Figure 4 As shown, the coloring efficiency is as high as 51.0 cm 2 / C.

[0044] The prepared electrochromic functional film samples were subjected to 1000 consecutive stability tests. The electrochromic stability test results of the electrochromic functional film samples are as follows: Figure 7 As shown, during the 1000 times repeated coloring and fading process, the measured current density of the sample did not change significantly, indicating that the material has good cycle stability.

[0045] The above test results show that the titanium-doped tungsten oxide electrochromic thin film material prepared in Example 1 has a transmission modulation amplitude of 53.7% at 600 nm and a reflection modulation amplitude of 42.0% at 480 nm, which can well buffer the volume change of the electrode during the redox reaction and is beneficial to the cyclic stability of the material; the thin film material has a wide range of modulation in the visible band (380~780nm), a short reaction time, and a coloring efficiency of 51.0 cm 2 / C.

[0046] For Example 2: The thin film material prepared in this example was tested according to the method of Example 1. The electrochromic coloring efficiency test results of the electrochromic functional thin film sample are as follows: Figure 8 As shown, the coloring efficiency is as high as 48.5 cm 2 / C; the transmission modulation amplitude of the prepared titanium-doped tungsten oxide electrochromic thin film material at 600 nm is 52.3%; the reflection modulation amplitude at 480 nm can reach 43.2%. The corresponding front and back color photos of the real object are shown in Fig.12 shown.

[0047] For Example 3: The thin film material prepared in this example was tested according to the method of Example 1. The electrochromic coloring efficiency test results of the electrochromic functional thin film sample are as follows: Fig. 9 As shown, the coloring efficiency is as high as 47.0 cm 2 / C; the transmission modulation amplitude of the prepared titanium-doped tungsten oxide electrochromic thin film material at 600 nm is 53.6%; the reflection modulation amplitude at 480 nm can reach 42.1%. The corresponding front and back color photos of the real object are shown in Fig.13 shown.

[0048] For Example 4: The thin film material prepared in this example was tested according to the method of Example 1. The electrochromic coloring efficiency test results of the electrochromic functional thin film sample are as follows: Fig.10 As shown, the coloring efficiency is as high as 44.1 cm 2 / C; the transmission modulation amplitude of the prepared titanium-doped tungsten oxide electrochromic thin film material at 600 nm is 51.7%; the reflection modulation amplitude at 480 nm can reach 44.5%. The corresponding front and back color photos of the real object are shown in Fig.14 shown.

[0049] For Comparative Example 1: The thin film material prepared in this example was tested according to the method of Example 1. The electrochromic coloring efficiency test results of the electrochromic functional thin film sample are as follows: Fig.11 As shown, the coloring efficiency is 43.4 cm 2 / C; the transmission modulation amplitude of the prepared titanium-doped tungsten oxide electrochromic thin film material at 600 nm is 49.9%; the reflection modulation amplitude at 480 nm is 45.6%. The electrochromic stability test results of the electrochromic functional thin film sample are as follows Fig.16 As shown, during the fading process repeated 1000 times, the measured current density difference of the samples increased significantly, that is, the stability was poor.

[0050] Using the constant potential polarization method, voltages of -0.1, -0.2, -0.3, -0.4, -0.5V and +0.5V were applied to the prepared electrochromic functional film samples, and the colors of both sides of the film material were observed to change. During the color change process, the front and back color photos of the corresponding real objects are shown in Fig.15 As shown: Observe from the front: apply voltage -0.1, -0.2, -0.3, -0.4, -0.5 V, the sample color changes from the initial blue to indigo, purple, dark purple and other colors, when the applied voltage changes to +0.5 V, the sample color returns to the initial blue; observe from the reverse side: apply voltage -0.1, -0.2, -0.3, -0.4, -0.5 V, the sample color changes from the initial lavender to blue-gray, when the applied voltage changes to +0.5V, the sample color returns to the initial lavender. Display samples show rich changes in color types. However, compared with Example 1, the types of color changes are less, which is due to the doping of titanium dioxide, which makes the reflectivity change of the thin film sample more obvious, or for the doped sample, the applied voltage makes the reflectivity change of the thin film larger, so the types of color changes are richer.

[0051] For Comparative Example 2: Using the constant potential polarization method, voltages of -0.1, -0.2, -0.3, -0.4, -0.5V and +0.5V were applied to the prepared electrochromic functional film sample, and the color of both sides of the film material was observed to change. During the color change process, the color photos of the front and back sides of the sample are as follows: Fig.17 As shown: the color change of the front and back sides of the sample is the same. This is because there is no metal layer and the sample is transparent, that is, the effect is the same when observed from both sides. Specifically: when the voltage is applied -0.1, -0.2, -0.3, -0.4, and -0.5V, the color of the front and back sides of the sample changes from transparent to dark blue. When +0.5V is applied, the sample becomes transparent again.

[0052] For Comparative Example 3: Using the constant potential polarization method, voltages including -0.1, -0.2, -0.3, -0.4, -0.5 and +0.5 V were applied to the electrochromic functional film sample prepared in Example 1, and only the color of the front side of the film material was observed to change. The color photos of the front and back sides of the corresponding objects are shown in FIG. Fig.18 As shown, when observed from the front: applying voltages of -0.1, -0.2, -0.3, -0.4, and -0.5 V, the color of the sample changes from the initial blue to various colors such as dark blue, purple, dark purple, and brown. When the applied voltage changes to +0.5 V, the color of the sample returns to the initial blue state. Since the metal thickness of the first functional layer is relatively thick and the sample is not light-transmissive, the color of the reverse side does not change. The electrochromic stability test results of the electrochromic functional film samples are shown in Figure 1. Fig.19 As shown, during the 1000 times of repeated fading, the measured current density difference of the sample increased significantly, that is, the stability was poor. This is because the metal of the first functional layer is thicker and the adhesion between the metal and the substrate is poor. During the 1000 times of repeated fading, part of the film will fall off from the substrate, so its stability is poor.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An electrochromic thin film material, characterized in that: The electrochromic thin film material is a multi-layer composite structure, including a conductive substrate layer, a first functional layer and a second functional layer arranged in sequence from bottom to top; the first functional layer is a metal layer, and the metal material in the metal layer includes tungsten; the second functional layer is a composite metal oxide layer, and the oxide in the composite metal oxide layer is selected from a composite of tungsten oxide and titanium oxide; The thickness of the first functional layer is 8-12 nm; the thickness of the second functional layer is 180-220 nm.

2. The electrochromic thin film material according to claim 1, characterized in that: The thickness of the first functional layer is 10 nm; the thickness of the second functional layer is 200 nm.

3. The electrochromic thin film material according to claim 1, characterized in that: The conductive substrate layer is one of commercial ITO conductive glass or FTO conductive glass.

4. A method for preparing an electrochromic thin film material according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1, depositing metal tungsten on the surface of the pretreated conductive substrate by magnetron sputtering to obtain a first functional layer; S2. Depositing metal tungsten and metal oxide on the surface of the first functional layer by magnetron sputtering to obtain a second functional layer.

5. The preparation method according to claim 4, characterized in that: In step S1, the specific operation of the pretreatment is: ultrasonically cleaning the conductive substrate with acetone, ethanol and deionized water for 20 to 30 minutes respectively, and then drying it in a vacuum oven.

6. The preparation method according to claim 4, characterized in that: In step S1, the target material in the magnetron sputtering method is metal tungsten, which is placed in a single DC target, the sputtering power is 100 W, the sputtering pressure is 0.2~0.5 Pa, the sputtering time is 1~5min, the working atmosphere is argon, and the gas flow rate of the argon is 20~60 sccm.

7. The preparation method according to claim 4, characterized in that: In step S2, the target materials in the magnetron sputtering method are metal tungsten and titanium oxide. The metal tungsten is placed in a DC target with a sputtering power of 100 W; the titanium oxide is placed in a RF target with a sputtering power of 50-100 W.

8. The preparation method according to claim 7, characterized in that: In the magnetron sputtering method, the sputtering gas pressure is 0.3-0.6 Pa, the sputtering time is 15-30 min, the working atmosphere is a mixed atmosphere of argon and oxygen, and the gas flow rates of the argon and oxygen are 30-60 sccm and 10-20 sccm, respectively.

9. Use of the electrochromic thin film material according to any one of claims 1 to 3 in an electrochromic device.

10. The use according to claim 9, characterized in that The light-transmitting color-changing effect of the electrochromic thin film material in the electrochromic device has the following performance characteristics: In reflective mode, the two sides appear different colors, and in transmissive mode, they are light-transmissive; The front side can achieve a reversible change from sky blue to dark purple when a voltage of -0.5V to +0.5V is applied; The back side can achieve a reversible change from light red to dark brown when a voltage of -0.5V to +0.5V is applied; The coloring efficiency is 44.1~51.0 cm² / C.

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