High-stability electrochromic thin film and preparation method and application thereof

Abstract

This invention discloses a highly stable electrochromic thin film, its preparation method, and its applications. The electrochromic thin film comprises a conductive material and an electrochromic layer. The electrochromic layer is a quasi-planar heterojunction metal oxide with a thickness of 10–1000 nm. The preparation method includes the following steps: fixing the conductive material on a sample holder and placing it in an electron beam cavity; pretreating the conductive material; and then using high-energy ion-assisted electron beam evaporation to deposit the metal oxide onto the conductive material, thereby obtaining the electrochromic thin film. This invention, employing the aforementioned highly stable electrochromic thin film, its preparation method, and its applications, overcomes the trade-off between high stability and ultrafast switching performance with the assistance of high-energy ions, exhibiting significant overall electrochromic performance, including high optical contrast, ultrafast switching speed, and excellent stability.

Description

Technical Field

[0001] This invention relates to the field of electrochromic thin film technology, and in particular to a highly stable electrochromic thin film, its preparation method, and its application. Background Technology

[0002] Electrochromism refers to the dynamic adjustment of the visual color and optical properties of electrochromic (EC) materials and devices through electrochemical redox reactions under relatively small external voltage or current stimulation. EC technology has enormous application potential in various fields, including smart windows in energy-efficient buildings, energy-saving displays, and adaptive camouflage systems. Currently, various advanced EC materials include organic polymers, inorganic metal oxides, and plasmonic nanomaterials. Among them, inorganic EC materials, such as transition metal oxides like tungsten oxide and nickel oxide, have gained considerable attention due to their excellent cost-performance ratio, abundant reserves, and unique photothermal stability. However, most inorganic EC materials possess inherent brittleness and a dense microstructure, posing a significant challenge to the development of EC materials and devices. This strongly limits their development and widespread practical application when combining ultrafast switching speeds, practically required durability, and perfect mechanical flexibility. Current research has attempted to improve the performance of WO3 thin films by optimizing the deposition process and interface design. However, existing technologies have not fully utilized quasi-planar heterogeneous interface design to effectively enhance electrochromic performance, especially in improving response speed and stability, where significant room for improvement remains.

[0003] To address these challenges, various strategies are being explored, such as developing nanostructured and / or composite electrolyte (EC) materials, optimizing electrolyte ions, and constructing novel electrode materials. Low-dimensional nanostructured EC films, including nanodots, nanowires, nanorods, nanosheets, and nanoporous films, can increase the contact area with the electrolyte, shorten charge transport distances, reduce internal stress, and significantly improve optical contrast, response time, and flexibility compared to traditional dense films. Although significant progress has been made with the help of nanotechnology, these performance improvements are often achieved at the expense of stability. This is because, during repeated cycling, high reactivity induces side reactions, leading to degradation of the microstructured liquid and a significant decrease in stability.

[0004] Studies have shown that precisely tuning heterostructures in nanostructured electrolytic capacitor (EC) nanocomposites and planar heterostructures on the EC / electrolyte interlayer are also effective strategies for improving their overall performance. These works highlight the importance of heterostructure engineering and offer a promising approach to overcoming the inherent limitations of single-phase nanomaterials by creating abundant heterostructures to generate rapid mass and charge transfer. Some artificial solid electrolyte layers on the EC / electrolyte heterostructure can also act as buffers, enhancing the elasticity and stability of the film. In contrast, the modulation of the electrode / EC layer heterostructure is often neglected; this interface is where non-uniform electron transfer occurs and ion diffusion drives are generated, and it is expected to be closely related to the final EC performance. Recent reports have demonstrated the above hypothesis that the performance of ECs can be effectively improved by constructing nanostructured interfaces between the electrode and the EC layer. For example, self-assembled two-dimensional TiO2 / Mxene heterostructures, with their good balance of porosity and connectivity, can improve ion and electron transport efficiency in flexible EC devices and exhibit superior mechanical and electrochemical stability (>1000 cycles). Furthermore, porous tin dioxide nanosheet scaffolds loaded with various active EC materials can significantly improve cycle durability (>2000 cycles) and optical modulation (WO3@SnO2 to 86%). However, obstacles remain in the large-scale, direct, and reliable controlled construction and integration of nanostructured heterostructures with customizable properties, highlighting the need to further enhance heterostructure interface design for widespread implementation. Summary of the Invention

[0005] The purpose of this invention is to provide a highly stable electrochromic thin film, its preparation method, and its application, in order to solve the problem that the improvement of the performance of the aforementioned EC materials usually comes at the cost of stability, and it is impossible to simultaneously improve both performance and stability.

[0006] To achieve the above objectives, the first aspect of the present invention provides a highly stable electrochromic thin film, the electrochromic thin film comprising a conductive material and an electrochromic layer, the electrochromic layer being a quasi-planar heterojunction metal oxide, and the thickness of the electrochromic layer being 10–1000 nm.

[0007] Preferably, the metal oxide is one or more of WO3, MoO3, NiO, and TiO2.

[0008] The metal oxides prepared in this invention are not limited to the above-mentioned types. Any metal oxide that can be applied to electrochromic thin films can be used to prepare the corresponding quasi-planar heterostructure (Q-PHI) using the preparation method specified in this invention.

[0009] Preferably, the conductive material includes a substrate and an electrode. The substrate mainly serves a supporting function, and both the substrate and the electrode can be selected from commonly used materials in the field according to actual needs.

[0010] More preferably, the substrate is one of glass, polyethylene terephthalate (PET), or a metal substrate.

[0011] More preferably, the electrode is one of indium tin oxide (ITO), FTO, and indium cerium oxide.

[0012] A second aspect of this invention provides a method for preparing a highly stable electrochromic thin film, comprising the following steps:

[0013] The conductive material is fixed on the sample holder and placed in the electron beam cavity. The conductive material is pretreated and then high-energy ion-assisted electron beam evaporation is used to deposit metal oxides onto the conductive material to obtain an electrochromic thin film.

[0014] Preferably, the conductive material in this invention can be self-made or purchased directly.

[0015] The process of making the conductive material in-house is as follows: the substrate is ultrasonically cleaned sequentially with acetone, ethanol, and deionized water. After cleaning, the substrate is fixed on a sample holder and placed in an electron beam cavity. Electrodes are deposited on the substrate surface to form the conductive material. The conductive material can then be pretreated without further cleaning. However, if the conductive material is purchased directly, cleaning is required. The cleaning process involves ultrasonically cleaning the conductive material sequentially with acetone, ethanol, and deionized water.

[0016] Preferably, the vacuum level inside the electron beam cavity is 1×10⁻⁶. -4 Pa ~ 5 × 10 -3 Pa, using high-energy ion bombardment of the conductive material surface for pretreatment.

[0017] Preferably, the pretreatment time is 1 to 30 minutes.

[0018] Preferably, the metal oxide is subjected to a flow rate of 0.1–1 nm·s at a temperature of 20–300 °C. -1 The vapor deposition rate is used to deposit the material onto the pretreated conductive material.

[0019] Preferably, the high-energy ion is one or more of oxygen ions, argon ions, and nitrogen ions.

[0020] Preferably, the accelerating voltage for high-energy ions is 130–300V.

[0021] The high-energy ion source in this invention is one of the following: a Hall ion source, a Kaufman ion source, or a radio frequency ion source. The processes for generating high-energy ions using Hall ion sources, Kaufman ion sources, and radio frequency ion sources are all commonly used in existing technologies. The Hall ion source utilizes the Hall effect to generate plasma and accelerates ions in the plasma using an accelerating electric field to produce high-energy ions. Its working process is as follows:

[0022] Hall effect: In a Hall ion source, when an electron source (usually a thermionic source or electron gun) moves in a strong magnetic field, it is subjected to the Lorentz force, causing the electrons to move in a circular motion in the electric field. Through collisions between the electrons and gas atoms or molecules, ions in the plasma are generated.

[0023] Plasma generation: Under the Hall effect, the magnetic field and electric field work together to accelerate electrons in the electric field and collide with oxygen or argon molecules, producing oxygen ions and / or argon ions as well as free electrons, thus forming plasma. The oxygen ions and / or argon ions in these plasmas are accelerated by the electric field to form high-energy oxygen ions and / or argon ions.

[0024] A third aspect of the present invention provides an electrochromic device comprising an electrochromic thin film, an electrolyte layer, a conductive layer and a protective layer obtained by the above preparation method.

[0025] In the electrochromic device of this invention, a gel electrolyte is used as the electrolyte layer, the conductive layer can be one of commonly used electrodes such as ITO and FTO, and the protective layer can be one of commonly used materials such as PET and glass. Depending on the actual application process, double-sided adhesive tape can also be used as an adhesive and gasket during the fabrication of the electrochromic device, with the edges sealed using an ultraviolet-cured adhesive. The thickness of the double-sided adhesive tape is generally 0.5–1.2 mm, more preferably 1 mm.

[0026] Preferably, the electrolyte layer is a gel electrolyte. PMMA and PC are mixed evenly and heated in an oven at 60-80°C for 15-20 hours to obtain a transparent gel. Then, LiClO4 and acetonitrile are added, and the mixture is stirred on a magnetic stirrer at 60-80°C for 10-15 hours to ensure that the electrolyte salts are evenly distributed in the transparent gel, thus forming a gel electrolyte.

[0027] Preferably, the molecular weight of PMMA is 100,000 to 150,000, and the mass ratio of PMMA, PC, LiClO4 and acetonitrile is (3 to 5): (8 to 12): (1 to 2): (5 to 10).

[0028] Therefore, the present invention, employing the above-mentioned highly stable electrochromic thin film, its preparation method, and its application, has the following beneficial effects:

[0029] (1) This invention differs from traditional planar heterointerfaces and nanostructured heterointerfaces by significantly broadening the nanoscale interfacial contact and unique longitudinal gradient distribution characteristics with the aid of high-energy ions. The unique quasi-planar heterointerface metal oxide can generate a strong built-in electric field and strong interfacial bonding, greatly promoting the transport dynamics of electrons and ions and enhancing the Li... + The surface adsorption effectively releases stress during continuous electrochemical cycling. Therefore, the electrochromic thin film formed by quasi-planar heterojunction metal oxides overcomes the trade-off between high stability and ultrafast switching performance, exhibiting significant overall EC performance, including high optical contrast, ultrafast switching speed, and excellent stability.

[0030] (2) This invention can also realize large-area, flexible EC smart windows composed of electrochromic thin films. This invention provides a novel design concept and a simple, effective and scalable strategy for the fabrication of high-performance EC thin films and devices by constructing quasi-planar heterojunction metal oxides.

[0031] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0032] Figure 1 This is a schematic diagram illustrating the preparation of the electrochromic thin film according to the present invention;

[0033] Figure 2 The surface morphology diagrams are of ITO in Example 1 and Comparative Example 1;

[0034] Figure 3 Cross-sectional scanning electron microscope (SEM) images, ToF-SIMS depth profile maps, and In... of the electrochromic films in Example 1 and Comparative Example 2. + The signal curve amplified from 0-1000s;

[0035] Figure 4 Cross-sectional views of the electrochromic films in Example 3 and Comparative Example 3 obtained by scanning electron microscopy, and their transmittance curves in the visible light range (380-780 nm).

[0036] Figure 5 The initial transmission spectrum and color transmission spectrum of the electrochromic film in Example 3 and Comparative Example 3 at 380-2500 nm, the in-situ transmittance curve under 20s voltage, the in-situ transmittance curve after 1000 cycles, and the in-situ transmittance curve after 10000 cycles are shown.

[0037] Figure 6 Cross-sectional views of the electrochromic films in Example 2 and Comparative Example 4 obtained by scanning electron microscopy;

[0038] Figure 7Cross-sectional views of the electrochromic films in Example 4 and Comparative Example 5 obtained by scanning electron microscopy;

[0039] Figure 8 The diagram shows the structure of the flexible electrochromic device in Application Example 1, along with its transmittance curves and digital photographs under different driving voltages.

[0040] Figure 9 This is a schematic diagram of the structure of an electrochromic thin film.

[0041] Figure 10 This is a schematic diagram of the structure of an electrochromic device;

[0042] Figure 11 Cross-sectional views of the electrochromic films in Example 6 and Comparative Example 6 obtained by scanning electron microscopy;

[0043] In the diagram: 1. Substrate; 2. Electrode; 3. Electrochromic layer; 4. Electrolyte layer; 5. Conductive layer; 6. Protective layer. Detailed Implementation

[0044] The present invention will be further described below. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation methods and specific operation processes, but the present invention is not limited to this embodiment.

[0045] Example 1

[0046] This embodiment provides a highly stable electrochromic thin film, which includes a substrate, an electrode, and an electrochromic layer. The substrate is a transparent substrate made of glass, and the electrode is a transparent electrode made of indium tin oxide (ITO). The glass and the ITO electrode together form a transparent conductive material (glass / ITO). The conductive material is purchased directly. The electrochromic layer is a quasi-planar heterojunction tungsten oxide with a thickness of 40 nm.

[0047] Figure 1 This is a schematic diagram of the preparation method of the present invention. The specific preparation process includes the following steps:

[0048] (1) The transparent conductive material was cleaned by ultrasonic treatment with acetone, ethanol and deionized water for 15 minutes in sequence, and then dried in an oven at 80°C.

[0049] (2) Fix the cleaned and dried transparent conductive material onto the sample holder, and then place it in the electron beam cavity. When the vacuum level in the cavity reaches 3×10⁻⁶, -3 At Pa, the transparent conductive material is pretreated by bombarding its surface with high-energy oxygen ions for 2 minutes. Then, it is subjected to a temperature of 100°C, as follows: Figure 1As shown, high-energy oxygen ion-assisted electron beam evaporation was used to evaporate tungsten oxide at a wavelength of 0.35 nm·s⁻¹. -1 At a certain rate, the film was deposited on a transparent conductive material substrate by vapor deposition, with a film thickness of 40 nm, to obtain an electrochromic thin film (Q-PHI WO3). The structural diagram of the electrochromic thin film is shown below. Figure 9 During the deposition process, the anolyte voltage for generating high-energy oxygen ions is 150V, and the oxygen flux is maintained at a rate of 15sccm.

[0050] High-energy oxygen ions are generated by a Hall ion source, and the generation process can be carried out using preparation methods commonly used in this field.

[0051] Example 2

[0052] This embodiment provides a highly stable electrochromic thin film. The electrochromic thin film includes a substrate, an electrode, and an electrochromic layer. The substrate is a transparent substrate, made of transparent glass. The electrode is a transparent electrode, made of indium tin oxide. The glass and the indium tin oxide electrode together form a transparent conductive material (glass / ITO). The conductive material is purchased directly. The electrochromic layer is a quasi-planar heterojunction tungsten oxide with a thickness of 100 nm.

[0053] The specific preparation process includes the following steps:

[0054] (1) The transparent conductive material was cleaned by ultrasonic treatment with acetone, ethanol and deionized water for 15 minutes in sequence, and then dried in an oven at 80°C.

[0055] (2) Fix the cleaned and dried transparent conductive material onto the sample holder, and then place it in the electron beam cavity. When the vacuum level in the cavity reaches 3×10⁻⁶, -3 At Pa, the transparent conductive material was pretreated by bombarding its surface with high-energy argon ions for 2 minutes. Then, at 100°C, tungsten oxide was evaporated using a high-energy argon ion-assisted electron beam at a speed of 0.35 nm. -1 An electrochromic thin film was obtained by vapor deposition on a transparent conductive material substrate at a rate of 150V, with a film thickness of 100nm. During the deposition process, the anolyte voltage for generating high-energy argon ions was 150V, and the argon flux was maintained at a rate of 15sccm.

[0056] High-energy argon ions are generated by a Hall ion source.

[0057] Example 3

[0058] This embodiment provides a highly stable electrochromic thin film, which includes a substrate, an electrode, and an electrochromic layer. The substrate is a transparent substrate made of transparent glass. The electrode is a transparent electrode made of indium tin oxide (ITO). The glass and the ITO electrode together form a transparent conductive material (glass / ITO). The conductive material is purchased directly. The electrochromic layer is a quasi-planar heterojunction tungsten oxide with a thickness of 200 nm.

[0059] The specific preparation process includes the following steps:

[0060] (1) The transparent conductive material was cleaned by ultrasonic treatment with acetone, ethanol and deionized water for 15 minutes in sequence, and then dried in an oven at 80°C.

[0061] (2) Fix the cleaned and dried transparent conductive material onto the sample holder, and then place it in the electron beam cavity. When the vacuum level in the cavity reaches 1×10⁻⁶, -3 At Pa, the transparent conductive material was pretreated by bombarding its surface with high-energy oxygen ions for 2 minutes. Then, at 120°C, tungsten oxide was evaporated using a high-energy oxygen ion-assisted electron beam at a wavelength of 0.35 nm. -1 An electrochromic thin film was obtained by vapor deposition on a transparent conductive material substrate at a rate of 150V, with a film thickness of 200nm. During the deposition process, the anolyte voltage for generating high-energy oxygen ions was 150V, and the oxygen flux was maintained at a rate of 15sccm.

[0062] High-energy oxygen ions are generated by a Hall ion source.

[0063] Example 4

[0064] This embodiment provides a highly stable electrochromic film, which includes a substrate, an electrode, and an electrochromic layer. The substrate is a transparent substrate made of polyethylene terephthalate (PET). The electrode is a transparent electrode made of indium tin oxide (ITO). The PET and ITO electrode together form a transparent conductive material (PET / ITO). The conductive material is purchased directly. The electrochromic layer is a quasi-planar heterojunction tungsten oxide with a thickness of 400 nm.

[0065] The specific preparation process includes the following steps:

[0066] (1) The transparent conductive material was cleaned by ultrasonic treatment with acetone, ethanol and deionized water for 15 minutes in sequence, and then dried in an oven at 80°C.

[0067] (2) Fix the cleaned and dried transparent conductive material onto the sample holder, and then place it in the electron beam cavity. When the vacuum level in the cavity reaches 5×10⁻⁶, -3At Pa, the transparent conductive material was pretreated by bombarding its surface with high-energy oxygen and argon ions for 2 minutes. Then, at 80°C, tungsten oxide was evaporated using a high-energy oxygen and argon ion-assisted electron beam at a velocity of 0.35 nm / s. -1 An electrochromic thin film was obtained by vapor deposition on a transparent conductive material substrate at a rate of 400 nm. During the deposition process, the anolyte voltage for generating high-energy oxygen and argon ions was 150 V, and the oxygen flux and argon flux were maintained at a rate of 7.5 sccm.

[0068] High-energy oxygen ions and high-energy argon ions are generated by a Hall ion source.

[0069] Application Example 1

[0070] This application example first adopts the preparation method of Examples 1-4, depositing quasi-planar heterointerface tungsten oxide with a thickness of 40-400 nm on a transparent conductive material to form an electrochromic film with polyethylene terephthalate (PET) or transparent glass as a transparent substrate, indium tin oxide as a counter electrode, and quasi-planar heterointerface tungsten oxide (Q-PHI WO3) as an electrochromic layer.

[0071] An electrochromic film was applied to a large-area flexible electrochromic device. The device uses a gel electrolyte as the electrolyte layer, indium tin oxide as the transparent conductive electrode, and polyethylene terephthalate or transparent glass as the transparent protective layer. A 1mm thick double-sided adhesive tape was used as both an adhesive and a gasket. The edges of the electrochromic device were sealed with a UV-cured adhesive. A structural diagram of the electrochromic device is shown below. Figure 10 .

[0072] Specifically, using the electrochromic film (PET / ITO / Q-PHI WO3) prepared in Example 4, the gel electrolyte was uniformly coated on the surface of PET / ITO / Q-PHI WO3, and double-sided tape was attached around the perimeter of PET / ITO / Q-PHI WO3. Then, a conductive layer (ITO) and a protective layer (PET) were applied to cover the film, the two film layers were fixed firmly, air bubbles were removed, and the edges of the device were bonded with UV-curable adhesive.

[0073] The preparation method of the gel electrolyte is as follows: 3.5g of PMMA (M W =120000) and 10g of PC are mixed in a 100mL flask and heated in a 70℃ oven for 17h to allow the transparent polymer material to swell well in the polymer swelling agent. Then, 1.5g of LiClO4 and 6g of acetonitrile are added to the gel, and then the mixture is stirred on a magnetic stirrer at 70℃ for 12h to allow the electrolyte salt to be evenly distributed in the transparent gel, thus forming a transparent gel electrolyte.

[0074] This lightweight and flexible device can achieve dynamic and continuous transparency and color adjustment under various driving voltages. For example... Figure 8 As shown, Figure 8 (a) is a schematic diagram of the structure of a flexible electrochromic device based on Q-PHI WO3; (b) transmittance curves and digital photographs of a 20cm×15cm flexible electrochromic device based on Q-PHI WO3 under different driving voltages.

[0075] The device was initially highly transparent, with an average transmittance of 79.4% in the 400–1000 nm range. When a voltage of -3.5 V was applied, the color changed to light blue; as the voltage was further increased to -3.8 V, the color deepened to dark blue. At 1000 nm, the flexible EC device achieved a maximum optical contrast ratio of 67.6%. The device's unique light modulation performance in a bent state demonstrates the significant application potential of Q-PHI WO3 thin films in flexible displays, lightweight smart windows, and wearable integrated systems.

[0076] Comparative Example 1

[0077] This comparative example is based on Example 1, using the same cleaning steps and drying in an oven at 80°C. Comparative Example 1 did not undergo high-energy oxygen ion bombardment pretreatment after cleaning; the remaining steps were the same as in Example 1.

[0078] This invention tests the pretreated ITO electrode surfaces of Example 1 and Comparative Example 1 to further illustrate the advantages of the ITO electrode surface treated in Example 1. Scanning electron microscopy and atomic force microscopy were used to characterize the surface morphology of Example 1 and Comparative Example 1, and the specific results are as follows:

[0079] like Figure 2 b and Figure 2 As shown in Figure d, the surface of the ITO electrode after high-energy oxygen ion pretreatment is relatively rough, with a roughness of 3.7 nm. In contrast, the surface of the ITO electrode without high-energy oxygen ion treatment is very smooth. Figure 2 a and Figure 2 As shown in c, the surface roughness is 2.7 nm.

[0080] Comparative Example 2

[0081] This comparative example is based on Example 1. The only difference between this example and Example 1 is that, during the deposition process, high-energy oxygen ion-assisted electron beam evaporation is not used, and no auxiliary deposition is performed. The electrochromic layer deposited in this comparative example is t-WO3.

[0082] The present invention tested the films of Example 1 and Comparative Example 2 respectively to further illustrate the advantages of the electrochromic film of Example 1.

[0083] The thin films of Example 1 and Comparative Example 2 were subjected to scanning electron microscopy and time-of-flight secondary ion mass spectrometry (ToF-SIMS) to characterize the interfacial elemental distribution, such as... Figure 3 As shown, the specific results are as follows: From Figure 3 The cross-sectional images from the scanning electron microscope (SEM) show that the film thicknesses of both Q-PHI WO3 and t-WO3 are 40 nm. This is based on the three-dimensional elemental distribution and cross-sectional depth (…). Figure 3 bc) It can be clearly seen that in Q-PHI WO3 In + The signal is distributed throughout the entire 40nm thick film. After sputtering for 1000s, In + The signal strength increased significantly, while WO + The signal is still saturated. Conversely, when In + When the signal reaches its saturation point, WO + The signal exhibits a very small drop. In contrast, the conventional interface formed between ITO and t-WO3 is quite thin (approximately 4 nm) because of the In in t-WO3. + The intensity is almost undetectable even after 1000 seconds of sputtering. Furthermore, during further etching, In... + and WO + The signals exhibited almost simultaneous and opposite trends. These results provide clear evidence of a significantly extended (>40 nm) longitudinal gradient distribution between the ITO and Q-PHI WO3 interlayers, which is very different from the ultrathin interlayer between conventional ITO and t-WO3 films prepared in Example 1.

[0084] Comparative Example 3

[0085] This comparative example is based on Example 3. The only difference between this example and Example 3 is that, during the deposition process, high-energy oxygen ion-assisted electron beam evaporation is not used, and no auxiliary deposition is performed. The electrochromic layer deposited in this comparative example is t-WO3.

[0086] The films of Example 3 and Comparative Example 3 were tested respectively to further illustrate the advantages of the Q-PHI WO3 film of Example 3.

[0087] First, the transmittance of Example 3 and Comparative Example 3 was measured using scanning electron microscopy and in the visible light range, respectively, to characterize their morphology and transmittance. The specific results are as follows: Cross-sectional SEM image ( Figure 4(ab) shows a clear difference in interface characteristics. The ITO / t-WO3 interface is easily identifiable, while the ITO / Q-PHI WO3 interface is noticeably denser and almost fused together. Figure 4 The initial transmittance spectrum in c shows that Glass / ITO / Q-PHI WO3 has an average transmittance of 81.3% under visible light, similar to Glass / ITO / WO3 (80.4%).

[0088] Secondly, to evaluate the EC performance of Q-PHI WO3 and t-WO3 films, a voltage of ±0.9V (vs. Ag / AgCl) was applied to the films prepared in Example 3 and Comparative Example 3 for 20 seconds, and the changes in visible-near infrared transmittance were recorded in situ simultaneously to calculate their optical contrast and response time. Figure 5 As shown, Figure 5 (a) shows the initial and color transmission spectra of Q-PHI WO3 and t-WO3 in the range of 380-2500 nm; (b) shows the in-situ transmittance curves of Q-PHI WO3 and (c) t-WO3 under ±0.9V (vs. Ag / AgCl) for 20s; the inset is a digital photograph of Q-PHI WO3 and t-WO3 in bleached and colored states; (d) shows the in-situ transmittance curves of Q-PHI WO3 and t-WO3 after 1000 cycles under ±0.9V (vs. Ag / AgCl); (e) shows the in-situ transmittance curve of Q-PHI WO3 after 10000 cycles under ±0.9V (vs. Ag / AgCl).

[0089] Test results are as follows Figure 5 a and Figure 5 As shown in b, Q-PHI WO3 achieves an optical contrast ratio (ΔT) of 82.1% at 700 nm, while the ΔT of t-WO3 film is only 78.3%. Even at a wavelength of 2500 nm, Q-PHI WO3 achieves a ΔT of 58%, compared to 42% for t-WO3. The superior broadband light modulation capability of Q-PHI WO3 film also demonstrates its potential as a smart window for controlling solar radiation. Response time is defined as the time required for a 90% change in transmittance. The coloring and bleaching response times of Q-PHI WO3 film are only 2.4 s and 1.8 s, respectively. Compared to t-WO3 film, the average response time is improved by 3 times, with the latter's coloring and bleaching times being 4.7 s and 12.1 s, respectively.

[0090] Finally, to evaluate the electrochemical cycling stability of the WO3 films prepared in Example 3 and Comparative Example 3, a voltage of ±0.9V (vs. Ag / AgCl) was applied to Q-PHI WO3 and t-WO3, and they were cycled 1000 times, with the change in in-situ transmittance at 700 nm monitored. Figure 5 d and Figure 5 As shown in Figure e, the tint color of the t-WO3 film significantly decreased with increasing cycle number, and a marked degradation in optical contrast was observed. After 1000 consecutive electrochemical cycles, the optical contrast of the WO3 film only decreased to 41.6% of its initial value. In contrast, the tint color and optical contrast of Q-PHI WO3 increased with increasing cycle number. After 1000 cycles, the optical contrast reached 106.6% of its initial value, showing almost no decrease until 2000 cycles. Even after 10000 cycles, the optical contrast remained at 78.7% of its initial value. Therefore, the broadened and tightly anchored quasi-planar heterointerface plays a crucial role in enhancing interfacial bonding and effectively releasing stress, thus contributing to good cycling stability.

[0091] Example 5

[0092] This embodiment provides an electrochromic thin film with ultrafast response and high stability, which differs from Embodiment 3 in that the type of high-energy ion source is different. The EC device performance of the electrochromic thin films prepared under various ion source types was tested, and the specific ion source types and performance test results are shown in Table 1.

[0093] Table 1. Ion source types and EC performance test results for Example 5

[0094]

[0095]

[0096] Comparative Example 4

[0097] This comparative example is based on Example 2. The only difference between this example and Example 2 is that, during the deposition process, high-energy argon ion-assisted electron beam evaporation is not used, and no auxiliary deposition is performed. The electrochromic layer deposited in this comparative example is t-WO3.

[0098] Scanning electron microscopy was used to characterize the morphology of Example 2 and Comparative Example 4, respectively. The specific results are as follows: Cross-sectional SEM images ( Figure 6 The results show a clear difference in interface characteristics. The ITO / t-WO3 interface is easily identifiable, while the ITO / Q-PHI WO3 interface is noticeably denser and almost fused together.

[0099] Comparative Example 5

[0100] This comparative example is based on Example 4. The only difference from Example 4 is that, during the deposition process, high-energy oxygen ions and argon ions are not used to assist electron beam evaporation, and no auxiliary deposition is performed. The electrochromic layer deposited in this comparative example is t-WO3.

[0101] Scanning electron microscopy was used to characterize the morphology of Example 4 and Comparative Example 5, respectively. The specific results are as follows: Cross-sectional SEM images ( Figure 7 The results show a clear difference in interface characteristics. The ITO / t-WO3 interface is easily identifiable, while the ITO / Q-PHI WO3 interface is noticeably denser and almost fused together.

[0102] Example 6

[0103] This embodiment provides an electrochromic thin film, which includes a substrate, an electrode, and an electrochromic layer. The substrate is made of glass, the electrode is a transparent electrode, and an indium tin oxide electrode is used. The glass and indium tin oxide form a transparent electrode material. The electrochromic layer is a quasi-planar heterojunction nickel oxide, and the thickness of the electrochromic layer is 200 nm.

[0104] The specific preparation process includes the following steps:

[0105] (1) The glass substrate was ultrasonically cleaned sequentially with acetone, ethanol, and deionized water for 15 min each, and then dried in an oven at 80℃. The cleaned glass substrate was then fixed on a sample holder and placed inside the electron beam cavity. When the vacuum level inside the cavity reached 2.5 × 10⁻⁶, the substrate was dried. -3 At Pa, indium tin oxide is applied at a speed of 0.2 nm·s. -1 The material is deposited on a glass substrate at a rate of 180 nm to form a transparent conductive material (glass / ITO).

[0106] (2) Subsequently, at room temperature, nickel oxide was evaporated using a high-energy oxygen ion-assisted electron beam at a velocity of 0.15 nm·s⁻¹. -1 The film was deposited on a transparent conductive material at a rate of 15 sccm, resulting in a highly stable electrochromic thin film (ITO / Q-PHI NiO) with a thickness of 200 nm. During the deposition process, the anolyte voltage for generating high-energy oxygen ions was 170 V, and the oxygen flux was maintained at a rate of 15 sccm.

[0107] High-energy oxygen ions are generated by a Hall ion source.

[0108] Comparative Example 6

[0109] This comparative example is based on Example 6. The difference between this comparative example and Example 6 is that Comparative Example 6 does not undergo high-energy oxygen ion pretreatment and does not use high-energy oxygen ion-assisted electron beam evaporation during the deposition process. The remaining steps are the same as those in Example 6. The electrochromic layer deposited in this comparative example is t-NiO.

[0110] The present invention performs scanning electron microscopy tests on Example 6 and Comparative Example 6 respectively to characterize their morphology. The specific results are as follows:

[0111] Cross-sectional SEM image ( Figure 11 The results show a clear difference in interface characteristics. The ITO / t-NiO interface is easily identifiable, while the ITO / Q-PHI NiO interface is significantly denser and almost fused together.

[0112] Therefore, this invention presents an ultrafast-response and highly stable electrochromic thin film with the aforementioned structure and its preparation method. Unlike traditional planar heterointerfaces and nanostructured heterointerfaces, this invention, aided by high-energy oxygen, argon, or nitrogen ions, significantly broadens the nanoscale interfacial contact and creates unique longitudinal gradient distribution characteristics. The unique Q-PHI can generate a strong built-in electric field and strong interfacial bonding, greatly promoting the transport dynamics of electrons and ions and enhancing the Li... + The surface adsorption effectively releases stress during continuous electrochemical cycling. Therefore, the electrochromic film prepared in this invention overcomes the trade-off between high stability and ultrafast switching performance, exhibiting significant overall EC performance, including high optical contrast, ultrafast switching speed, and excellent stability.

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A highly stable electrochromic thin film, characterized in that: The electrochromic thin film includes a conductive material and an electrochromic layer. The electrochromic layer is a quasi-planar heterojunction metal oxide with a thickness of 10–1000 nm. The surface of the conductive material is pretreated by high-energy ion bombardment, and the metal oxide is formed on the pretreated conductive material by high-energy ion-assisted electron beam evaporation.

2. The high-stability electrochromic thin film according to claim 1, characterized in that: The metal oxide is one or more of WO3, MoO3, NiO, and TiO2.

3. The method for preparing a highly stable electrochromic thin film according to any one of claims 1 to 2, characterized in that: Includes the following steps: The conductive material is fixed on the sample holder and placed in the electron beam cavity. The conductive material is pretreated and then high-energy ion-assisted electron beam evaporation is used to deposit metal oxides onto the conductive material to obtain an electrochromic thin film.

4. The method for preparing a highly stable electrochromic thin film according to claim 3, characterized in that: The vacuum level inside the electron beam cavity is 1×10 -4 Pa ~ 5 × 10 -3 Pa, using high-energy ion bombardment of the conductive material surface for pretreatment.

5. The method for preparing a highly stable electrochromic thin film according to claim 3, characterized in that: At 20–300 °C, the metal oxide was subjected to a flow rate of 0.1–1 nm·s. -1 The vapor deposition rate is used to deposit the material onto the pretreated conductive material.

6. The method for preparing a highly stable electrochromic thin film according to claim 3, characterized in that: High-energy ions are one or more of oxygen ions, argon ions, and nitrogen ions.

7. The method for preparing a highly stable electrochromic thin film according to claim 6, characterized in that: The accelerating voltage for high-energy ions is 130–300 V.

8. An electrochromic device, characterized in that: The electrochromic device comprises an electrochromic thin film, an electrolyte layer, a conductive layer, and a protective layer obtained by the preparation method according to any one of claims 3 to 6.

9. An electrochromic device according to claim 8, characterized in that: The electrolyte layer is a gel electrolyte. The preparation method of the gel electrolyte is as follows: PMMA and PC are mixed evenly and heated in an oven at 60-80℃ for 15-20h to obtain a transparent gel. Then, LiClO4 and acetonitrile are added, and then the mixture is stirred on a magnetic stirrer at 60-80℃ for 10-15h to make the electrolyte salt evenly distributed in the transparent gel, thus forming the gel electrolyte.

10. An electrochromic device according to claim 9, characterized in that: The molecular weight of PMMA is 100,000 to 150,000, and the mass ratio of PMMA, PC, LiClO4 and acetonitrile is (3-5):(8-12):(1-2):(5-10).

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