HfO2 / Ag-NPs / HfO2 / VO2 composite film, and preparation method and application thereof

Abstract

The application relates to the technical field of thermochromic film, in particular to a HfO2 / Ag-NPs / HfO2 / VO2 composite film and a preparation method and application thereof. The HfO2 / Ag-NPs / HfO2 / VO2 composite film comprises, from bottom to top, an HfO2 buffer layer (4), an Ag-NPs local surface plasmon resonance regulation layer (3), an HfO2 cover layer (2) and a VO2 thermochromic functional film layer (1); and the HfO2 buffer layer is combined with a quartz glass substrate. The application balances the optical performance and the color conforming to the building aesthetics of the composite film.

Description

Technical Field

[0001] This invention relates to the field of thermochromic thin film technology, and in particular to an HfO2 / Ag-NPs / HfO2 / VO2 composite thin film, its preparation method, and its application. Background Technology

[0002] To improve the energy efficiency of architectural glass, various energy-saving coated glasses have been developed, mainly including low-emissivity glass, electrochromic glass, and photochromic glass. However, low-emissivity glass lacks the ability to regulate sunlight due to its fixed initial reflection wavelength; electrochromic and photochromic glasses adjust visible light transmittance by applying light intensity or electric field intensity to the glass, but lack the ability to sense ambient temperature. Therefore, smart windows with environmental sensing capabilities and the ability to dynamically adjust solar radiation have become a research hotspot. Vanadium dioxide (VO2) undergoes a reversible phase transition from metal to insulator at 68℃. Below the critical temperature, it is insulator, exhibiting high transmittance in the visible and near-infrared bands; above the critical temperature, it is metallic, providing high blocking effect for near-infrared bands while maintaining high visible light transmittance. Therefore, vanadium dioxide has become one of the important materials in the field of smart window research. However, in practical applications, intrinsic VO2 films do not conform to the aesthetically pleasing brownish-yellow color and high phase transition temperature of traditional VO2 films. T c And visible light transmittance, which is difficult to balance. T lum ) and solar energy regulation efficiency ( ΔT sol This severely restricts the commercial application of VO2 film smart windows.

[0003] There are roughly three methods to improve the performance of VO2 thin-film smart windows. First, increasing the bandgap of VO2 promotes a blue shift in the absorption edge. Second, depositing an anti-reflective layer on the surface of the VO2 thin film reduces visible light reflection and increases transmittance. Third, based on the equivalent medium theory, designing and fabricating subwavelength micro / nano structures (such as moth-eye structures) can also improve the visible light transmittance and solar energy regulation efficiency of the VO2 thin film by increasing surface roughness and reducing the surface equivalent refractive index. While these methods improve the thermochromic properties of VO2 thin films to some extent, they cannot effectively control the color of the VO2 thin film. Therefore, designing and fabricating novel VO2 composite thin films is key to resolving the contradiction between smart window performance and architectural aesthetics.

[0004] Numerous studies have demonstrated that the localized surface plasmon resonance (LSPR) characteristic peaks of noble metal nanoparticles (NPs) such as Au and Ag are typically located in the visible light range. The LSPR effect excited under incident light produces strong selective light absorption or scattering, resulting in different colors. One study proposed a smart window composite film with a VO2 / Au / VO2 sandwich structure. The addition of Au-NPs induces a strong LSPR effect in the visible light region, adjusting the VO2 film from yellowish-brown to a blue-green hue that aligns with the aesthetics of architectural glass. However, the high price of gold presents significant cost constraints for commercialization. Therefore, from a cost-reduction perspective, using relatively inexpensive silver (Ag) instead of gold (Au) as the LSPR modulation layer offers significant economic advantages.

[0005] However, directly using Ag-NPs to replace Au-NPs in the preparation of thermochromic composite films presents the following technical challenges: First, Ag-NPs exhibit poor thermal stability and are prone to morphological degradation during high-temperature fabrication. In the preparation of thermochromic composite films, the deposition of the VO2 functional layer typically requires high substrate temperatures (generally 450-550℃). Under these high-temperature conditions, Ag-NPs are susceptible to thermal migration, aggregation, and fusion growth, resulting in uneven particle size distribution and irregular morphology, thus significantly weakening their LSPR effect. In contrast, Au has a much higher melting point (1064℃) than Ag (961.8℃), and Au-NPs possess better chemical stability and anti-agglomeration ability at high temperatures, enabling them to maintain stable nanostructures and optical properties during VO2 deposition.

[0006] Secondly, Ag-NPs are easily oxidized, affecting the stability of their optical properties. In physical vapor deposition processes such as pulsed laser deposition or magnetron sputtering, a certain oxygen partial pressure is typically required to prepare high-quality oxide films. Ag is readily oxidized in high-temperature oxygen-containing environments to form Ag₂O or AgO, leading to significant changes or even complete loss of its surface plasmon resonance characteristics. Au, however, possesses excellent oxidation resistance, maintaining its metallic state even in high-temperature oxidizing atmospheres, ensuring the stable performance of the LSPR effect.

[0007] Third, Ag-NPs exhibit poor interfacial compatibility with the surrounding dielectric layer. In multilayer composite thin film structures, the interfacial quality between Ag-NPs and the upper and lower functional layers directly affects the overall optical performance and mechanical stability of the film. The interfacial bonding force between Ag and the oxide layer is relatively weak, making it prone to interfacial desorption or stress concentration during thermal cycling, leading to film cracking or performance degradation. Au, on the other hand, due to its chemical inertness and good interfacial compatibility, can form a more stable interfacial structure with oxides.

[0008] Fourth, the LSPR peak position of Ag-NPs is extremely sensitive to changes in the refractive index of the surrounding medium. In practical applications of thermochromic smart windows, the composite film needs to operate over a wide temperature range. The LSPR peak position of Ag-NPs will undergo significant red or blue shifts with changes in ambient temperature, leading to unstable film color and affecting the architectural aesthetics. Although the LSPR characteristics of Au-NPs also exhibit temperature dependence, the magnitude of these changes is relatively smaller, making it easier to achieve precise color control.

[0009] Therefore, despite Ag's significant cost advantage, the aforementioned technological bottlenecks make it difficult for Ag-NPs to directly replace Au-NPs in the preparation of high-performance thermochromic composite films. While existing technologies have successfully improved the brownish-yellow hue of VO2 by constructing Ag / VO2 composite structures, these structures often exhibit poor thermochromic performance, low solar energy regulation capabilities, and lack a stability protection mechanism for Ag-NPs during high-temperature preparation.

[0010] Therefore, there is an urgent need to develop a new composite thin film structure and preparation method that can fully utilize the cost advantage of Ag, and overcome the technical defects of Ag-NPs such as poor thermal stability, easy oxidation, and poor interfacial compatibility through reasonable structural design and process optimization, so as to realize the preparation of high-performance, low-cost thermochromic smart window film that meets the requirements of architectural aesthetics. Summary of the Invention

[0011] Based on the above, this invention provides an HfO2 / Ag-NPs / HfO2 / VO2 composite thin film, its preparation method, and its application. This HfO2 / Ag-NPs / HfO2 / VO2 composite thin film can change the brownish-yellow color of a VO2-based thermochromic thin film to blue-green without affecting the film's optical properties, thus improving solar energy regulation efficiency while reducing costs.

[0012] To achieve the above objectives, the present invention provides the following solution: One of the technical solutions of the present invention is an HfO2 / Ag-NPs / HfO2 / VO2 composite thin film, comprising an HfO2 buffer layer, an Ag-NPs localized surface plasmon modulation layer, an HfO2 capping layer, and a VO2 thermochromic functional thin film layer arranged sequentially from bottom to top; The HfO2 buffer layer is bonded to the substrate.

[0013] In a preferred embodiment of the present invention, the thickness of the HfO2 buffer layer is 5~200 nm. The thickness of the HfO2 buffer layer is the same as the thickness of the HfO2 capping layer, exhibiting a symmetrical distribution, thus providing a stable dielectric environment for the Ag-NPs localized surface plasmon modulation layer.

[0014] In a preferred embodiment of the present invention, the average particle size of the Ag-NPs localized surface plasmon modulation layer is 20~100nm.

[0015] In this invention, a localized surface plasmon resonance (SPAR) layer of Ag-NPs is obtained by sputtering a dense silver film onto the surface of an HfO2 buffer layer and then annealing it; the thickness of the silver film is 1~10 nm. If the silver film is too thin, the Ag-NPs formed by annealing are insufficient to generate a localized surface plasmon resonance effect; if it is too thick, the average particle size of the Ag-NPs formed by annealing will be too large, weakening the localized surface plasmon resonance effect.

[0016] In a preferred embodiment of the present invention, the thickness of the HfO2 capping layer is 5~200 nm. When the HfO2 capping layer is too thin, it cannot completely cover Ag-NPs, weakening the local surface plasmon resonance effect of Ag-NPs. When the HfO2 capping layer is too thick, interference peaks will appear in the transmission spectrum of the composite film, which is not conducive to obtaining high solar energy regulation efficiency.

[0017] In a preferred embodiment of the present invention, the thickness of the VO2 thermochromic functional film layer is 30-50 nm. When the thickness of the VO2 thermochromic functional film layer is too thin, the solar energy regulation efficiency of the composite film is low; when the thickness of the VO2 thermochromic functional film layer is too thick, the visible light transmittance of the composite film will be significantly reduced.

[0018] The substrate is a quartz glass substrate.

[0019] The second technical solution of the present invention is a method for preparing the above-mentioned HfO2 / Ag-NPs / HfO2 / VO2 composite thin film, comprising the following steps: A HfO2 buffer layer was prepared on the substrate surface using pulsed laser deposition. Then, an Ag-NPs localized surface plasmon modulation layer was grown on the HfO2 buffer layer using ion beam sputtering. Finally, an HfO2 capping layer and a VO2 thermochromic functional thin film layer were sequentially grown on the surface of the Ag-NPs localized surface plasmon modulation layer using pulsed laser deposition.

[0020] In a preferred embodiment of the present invention, the conditions for preparing an HfO2 buffer layer on a substrate surface using pulsed laser deposition are set as follows: the target material used for deposition is an HfO2 target, the oxygen pressure is 0.2~4 Pa, the oxygen flow rate is 5~50 sccm, the substrate temperature is 150~450℃, the laser frequency is 2~12 Hz, and the growth rate of the HfO2 buffer layer is 1~5 nm / min. If the oxygen pressure, oxygen flow rate, substrate temperature, and laser frequency are too high or too low during the deposition of the HfO2 buffer layer, the crystallinity of the HfO2 buffer layer will deteriorate. Therefore, the present invention preferably limits the deposition conditions of the HfO2 buffer layer to the above parameter ranges.

[0021] In a preferred embodiment of the present invention, the conditions for growing an Ag-NPs localized surface plasmon resonance layer on the HfO2 buffer layer using ion beam sputtering are set as follows: the chamber pressure is evacuated to below 5 Pa, the sputtering power is 2~15 W, the sputtering target is an Ag target, and the sputtering time is 20~120 s; the sputtered product is then annealed to obtain the Ag-NPs localized surface plasmon resonance layer. The reason for setting the above parameter range for growing the Ag-NPs localized surface plasmon resonance layer on the HfO2 buffer layer using ion beam sputtering is as follows: when the sputtering power is low, the Ag deposition rate is too low; when the sputtering power is high, the Ag deposition rate is too fast, which will lead to a loose initial structure and poor compactness of the Ag film; when the sputtering time is short, the obtained Ag-NPs are insufficient to generate a localized surface plasmon resonance effect; when the sputtering time is too long, the average particle size of the Ag-NPs will be too large, resulting in a weakening of the localized surface plasmon resonance effect.

[0022] The vacuum degree of the annealing process is 10. -1 Below Pa, the annealing temperature is 400~700℃, and the annealing time is 1~5h. Excessively high annealing temperature and prolonged annealing time can lead to grain engulfment and fusion growth of Ag-NPs, resulting in irregular surface morphology and excessively large average grain size. This weakens the local surface plasmon resonance effect of Ag-NPs, thus reducing the ability to control the color of VO2 films. Conversely, excessively low annealing temperature and short annealing time result in insufficient nucleation density and incomplete grain growth of Ag-NPs, forming a large number of excessively small and unevenly distributed particles. This fails to create an effective local surface plasmon resonance enhancement effect, thereby reducing the ability to control the optical properties of VO2 films.

[0023] In a preferred embodiment of the present invention, the conditions for growing an HfO2 capping layer on the surface of the Ag-NPs localized surface plasmon modulation layer using pulsed laser deposition are set as follows: the target material used for deposition is an HfO2 target, the oxygen pressure is 0.2~4 Pa, the oxygen flow rate is 5~50 sccm, the substrate temperature is 150~450℃, the laser frequency is 2~12 Hz, and the growth rate of the HfO2 capping layer is 1~5 nm / min. When depositing the HfO2 capping layer, if the oxygen pressure, oxygen flow rate, substrate temperature, and laser frequency are too high or too low, the crystallinity of the HfO2 capping layer will deteriorate.

[0024] The conditions for depositing a VO2 thermochromic functional thin film on the surface of an HfO2 capping layer using pulsed laser deposition were as follows: V target, oxygen pressure of 0.5-3 Pa, oxygen flow rate of 15-50 sccm, substrate temperature of 450-550℃, laser frequency of 1-5 Hz, and growth rate of the VO2 thermochromic functional thin film of 0.6-2.4 nm / min. When the oxygen pressure, oxygen flow rate, substrate temperature, and laser frequency are too high or too low during the deposition of the VO2 thermochromic functional thin film, the crystallinity of the VO2 thermochromic functional thin film deteriorates, which is detrimental to obtaining high solar energy regulation efficiency.

[0025] The Ag film prepared by the present invention using an ion sputtering instrument achieved good color matching effect over a wide range of annealing temperatures and times. The subsequent HfO2 / VO2 thin film was prepared using a pulsed laser deposition system. The preparation process does not rely on high-cost and high-precision processes and equipment such as templates and photolithography, making the preparation process simpler, more stable, and lower in cost.

[0026] The third technical solution of the present invention is the application of the above-mentioned HfO2 / Ag-NPs / HfO2 / VO2 composite film in a thermochromic smart window.

[0027] Compared with the prior art, the present invention has the following beneficial effects: This invention provides an HfO2 / Ag-NPs / HfO2 / VO2 composite thin film. An Ag-NPs are formed by sputtering an HfO2 buffer layer onto a glass substrate, followed by sputtering an Ag film onto the HfO2 buffer layer and annealing. The introduction of the HfO2 capping layer provides a stable dielectric environment for the Ag-NPs, preventing red-shift or blue-shift of the local surface plasmon resonance position of the Ag-NPs due to temperature changes, which would affect the solar energy regulation efficiency of the composite thin film. This achieves a balance between optical performance and color that conforms to architectural aesthetics.

[0028] The HfO2 / Ag-NPs / HfO2 / VO2 composite film of the present invention has a four-layer composite structure of HfO2 / Ag-NPs / HfO2 / VO2, which changes the brownish-yellow color of the VO2-based thermochromic film to a blue-green color that conforms to architectural aesthetics, while improving the thermochromic performance of the VO2-based thermochromic film. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 The diagram shows the structure of the HfO2 / Ag-NPs / HfO2 / VO2 composite thin film of the present invention, wherein: 1, VO2 thermochromic functional thin film layer; 2, HfO2 capping layer; 3, Ag-NPs localized surface plasmon modulation layer; 4, HfO2 buffer layer; 5, quartz glass substrate.

[0031] Figure 2 The image shows the transmittance spectrum of the Ag-NPs / VO2 composite film prepared in Comparative Example 1 in the visible-near infrared broadband region. The inset is a photograph of the actual product of Comparative Example 1.

[0032] Figure 3 The image shows the transmittance spectrum of the Ag-NPs / HfO2 / VO2 composite film prepared in Comparative Example 2 in the broad visible-near infrared spectral range. The inset is a photograph of the actual film in Comparative Example 2.

[0033] Figure 4 The image shows the transmittance spectrum of the HfO2 / Ag-NPs / HfO2 / VO2 composite film prepared in Example 1 in the visible-near infrared broadband region. The inset is a photograph of the actual product from Example 1.

[0034] Figure 5 The image shows the transmittance spectrum of the HfO2 / Ag-NPs / HfO2 / VO2 composite film prepared in Example 2 in the visible-near infrared broadband region. The inset is a photograph of the actual product from Example 2. Detailed Implementation

[0035] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0036] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0037] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0038] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0039] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0040] The first aspect of the present invention provides an HfO2 / Ag-NPs / HfO2 / VO2 composite thin film, comprising, from bottom to top, an HfO2 buffer layer 4, an Ag-NPs localized surface plasmon modulation layer 3, an HfO2 capping layer 2, and a VO2 thermochromic functional thin film layer 1.

[0041] The HfO2 buffer layer 4 is deposited on the quartz glass substrate 5, the Ag-NPs localized surface plasmon modulation layer 3 is deposited on the HfO2 buffer layer 4, the HfO2 capping layer 2 is deposited on the Ag-NPs localized surface plasmon modulation layer 3, and the VO2 thermochromic functional thin film layer 1 is deposited on the HfO2 capping layer 2.

[0042] The second aspect of this invention provides a method for preparing the HfO2 / Ag-NPs / HfO2 / VO2 composite thin film, comprising the following steps: placing a substrate in a pulsed laser deposition chamber, depositing an HfO2 buffer layer on the substrate, wherein the target material used for deposition is an HfO2 target, the oxygen pressure is 0.2~4 Pa, the oxygen flow rate is 5~50 sccm, the substrate temperature is 150~450℃, the laser frequency is 2~12 Hz, and the growth rate of the HfO2 buffer layer is 1~5 nm / min; placing the HfO2 buffer layer in an ion sputtering chamber, evacuating the chamber pressure to below 5 Pa, using an Ag target for sputtering, and sputtering for 20~120 s; and subjecting the sputtered sample to vacuum annealing for 1~5 h, with the vacuum level evacuated to 10 kPa. -1Below Pa, the annealing temperature is 400~700℃ to obtain Ag-NPs localized surface plasmon modulation layer 3; HfO2 capping layer 2 is deposited on Ag-NPs localized surface plasmon modulation layer 3, the target material is HfO2 target, the oxygen pressure is 0.2~4Pa, the oxygen flow rate is 5~50sccm, the substrate temperature is 150~450℃, the laser frequency is 2~12Hz, and the growth rate of HfO2 capping layer 2 is 1~5nm / min; VO2 thermochromic functional thin film layer 1 is deposited on HfO2 capping layer 2, the target material is V target, the oxygen pressure is 0.5~3Pa, the oxygen flow rate is 15~50sccm, the substrate temperature is 450~550℃, the laser frequency is 1~5Hz, and the growth rate of VO2 thermochromic functional thin film layer 1 is 0.6~2.4nm / min.

[0043] In this invention, the Ag-NPs localized surface plasmon modulation layer 3 is used to generate absorption peaks in the visible light range and regulate the color of the thin film. The HfO2 buffer layer 4 and the HfO2 capping layer 2 are used to provide a stable dielectric environment for the Ag-NPs localized surface plasmon modulation layer 3. The VO2 thermochromic functional thin film layer 1 is used to adjust the solar energy transmittance.

[0044] More preferably, other functional films may be introduced above or below the HfO2 / Ag-NPs / HfO2 / VO2 composite film to give the composite film better performance or function.

[0045] A third aspect of the present invention provides an application of the above-mentioned HfO2 / Ag-NPs / HfO2 / VO2 composite film in a thermochromic smart window.

[0046] This invention utilizes Ag-NPs to alter the brownish-yellow color of VO2-based thermochromic films, achieving a balance between excellent thermochromic performance and aesthetically pleasing colors in VO2 smart window films. This provides new ideas and theoretical guidance for the microstructure design of novel high-performance VO2-based smart windows.

[0047] Unless otherwise specified, the technical solutions described in this invention are all conventional solutions in the field, and the reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0048] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0049] A schematic diagram of the HfO2 / Ag-NPs / HfO2 / VO2 composite thin film structure of the present invention is shown below. Figure 1As shown, the structure includes: 1. VO2 thermochromic functional thin film layer; 2. HfO2 capping layer; 3. Ag-NPs localized surface plasmon modulation layer; 4. HfO2 buffer layer; 5. Quartz glass substrate.

[0050] The meanings of the abbreviations in this article are as follows: Ag-NPs: Silver nanoparticles; ΔT sol Solar energy regulation efficiency; T c Phase transition temperature; T lum Visible light transmittance.

[0051] Example 1 The preparation method of HfO2 / Ag-NPs / HfO2 / VO2 composite thin film is as follows: A glass substrate was placed in a pulsed laser deposition chamber, and an HfO2 buffer layer 4 was deposited on the substrate. The deposition target was an HfO2 target, the oxygen pressure was 1 Pa, the oxygen flow rate was 30 sccm, the substrate temperature was 400℃, the laser frequency was 5 Hz, the growth rate of the HfO2 buffer layer was 5 nm / min, and the deposition time was 5 min. The HfO2 buffer layer was then placed in an ion beam sputtering chamber, the chamber pressure was evacuated to below 5 Pa, the sputtering power was 10 W, the sputtering target was an Ag target, and the sputtering time was 30 s. The sputtered sample (a dense silver film with a thickness of 5 nm) was subjected to vacuum annealing for 2 h, and the vacuum degree was evacuated to 10. -1 Below Pa, with an annealing temperature of 400℃, an Ag-NPs localized surface plasmon modulation layer 3 was obtained, with an average Ag-NPs particle size of 45 nm. An HfO2 capping layer 2 was deposited on the localized surface plasmon modulation layer 3. The deposition target was an HfO2 target, the oxygen pressure was 0.2 Pa, the oxygen flow rate was 10 sccm, the substrate temperature was 250℃, the laser frequency was 5 Hz, the growth rate of the HfO2 capping layer 2 was 5 nm / min, and the deposition time was 5 min. A VO2 thermochromic functional thin film layer 1 was deposited on the HfO2 capping layer 2. The deposition target was a V target, the oxygen pressure was 0.9 Pa, the oxygen flow rate was 30 sccm, the substrate temperature was 480℃, the laser frequency was 2 Hz, the growth rate of the VO2 thermochromic functional thin film layer 1 was 1.2 nm / min, and the deposition time was 30 min. The resulting HfO2 / Ag-NPs / HfO2 / VO2 composite thin film was obtained.

[0052] The transmittance spectrum of the HfO2 / Ag-NPs / HfO2 / VO2 composite film was measured using a UV-3600 (Shimazu) UV-Vis-IR spectrophotometer. All tests were conducted under atmospheric conditions, and the results are as follows: Figure 4 As shown (illustration is a photograph of the actual product). By Figure 4 It can be seen that the HfO2 / Ag-NPs / HfO2 / VO2 composite film is blue-green and has a solar energy regulation efficiency of 8% in the wavelength range of 280-2650nm.

[0053] Example 2 The only difference from Example 1 is that the deposition time of the capping layer 2 is 20 min; all other steps and parameters are the same as in Example 1. A HfO2 / Ag-NPs / HfO2 / VO2 composite film was prepared.

[0054] The HfO2 / Ag-NPs / HfO2 / VO2 composite film prepared in this embodiment was subjected to the same performance verification as in Example 1, and the results are as follows: Figure 5 As shown (illustration is a photograph of the actual product). By Figure 5 It can be seen that the HfO2 / Ag-NPs / HfO2 / VO2 composite film is blue-green and has a solar energy regulation efficiency of 8.19% in the wavelength range of 280-2650nm.

[0055] Comparative Example 1 The only difference from Example 1 is that the deposition of buffer layer 4 and capping layer 2 is omitted; that is, the thermochromic functional thin film layer 1 is directly deposited on the localized surface plasma control layer 3. All other steps and parameters are the same as in Example 1. An Ag-NPs / VO2 composite thin film was prepared.

[0056] The composite film prepared in this comparative example was subjected to the same effect verification as in Example 1, and the results are as follows: Figure 2 As shown (illustration is a photograph of the actual product). By Figure 2 It can be seen that the Ag-NPs / VO2 composite film did not significantly change the brownish-yellow color of the VO2 film, and the solar energy regulation efficiency in the wavelength range of 280-2650nm was 3.46%.

[0057] Comparative Example 2 The only difference from Example 1 is that the deposition of the HfO2 buffer layer 4 is omitted, i.e., the localized surface plasmon modulation layer 3 is directly deposited on the substrate; all other steps and parameters are the same as in Example 1. An Ag-NPs / HfO2 / VO2 composite film was prepared.

[0058] The composite film prepared in this comparative example was subjected to the same effect verification as in Example 1, and the results are as follows: Figure 3 As shown (illustration is a photograph of the actual product). By Figure 3 It can be seen that although the Ag-NPs / VO2 composite film changes the brownish-yellow color of the VO2 film to some extent, its solar energy regulation efficiency in the wavelength range of 280-2650nm is 5.49%.

[0059] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A HfO2 / Ag-NPs / HfO2 / VO2 composite thin film, characterized in that, It includes, from bottom to top, an HfO2 buffer layer (4), an Ag-NPs localized surface plasma control layer (3), an HfO2 capping layer (2), and a VO2 thermochromic functional thin film layer (1). The HfO2 buffer layer is bonded to the substrate.

2. The HfO2 / Ag-NPs / HfO2 / VO2 composite film according to claim 1, characterized in that, The thickness of the HfO2 buffer layer (4) is 5~200nm.

3. The HfO2 / Ag-NPs / HfO2 / VO2 composite film according to claim 1, characterized in that, The average particle size of the Ag-NPs localized surface plasmon modulation layer (3) is 20~100nm.

4. The HfO2 / Ag-NPs / HfO2 / VO2 composite film according to claim 1, characterized in that, The thickness of the HfO2 capping layer (2) is 5~200nm.

5. The HfO2 / Ag-NPs / HfO2 / VO2 composite film according to claim 1, characterized in that, The thickness of the VO2 thermochromic functional thin film layer (1) is 30~50nm.

6. A method for preparing the HfO2 / Ag-NPs / HfO2 / VO2 composite thin film according to any one of claims 1 to 5, characterized in that, Includes the following steps: A HfO2 buffer layer (4) was prepared on the substrate surface by pulsed laser deposition. Then, an Ag-NPs localized surface plasmon modulation layer (3) was grown on the HfO2 buffer layer (4) by ion beam sputtering. Finally, an HfO2 capping layer (2) and a VO2 thermochromic functional thin film layer (1) were sequentially grown on the surface of the Ag-NPs localized surface plasmon modulation layer (3) by pulsed laser deposition.

7. The preparation method according to claim 6, characterized in that, The conditions for preparing the HfO2 buffer layer (4) on the substrate surface by pulsed laser deposition are as follows: the target material for deposition is HfO2 target, the oxygen pressure is 0.2~4Pa, the oxygen flow rate is 5~50sccm, the substrate temperature is 150~450℃, the laser frequency is 2~12Hz, and the growth rate of the HfO2 buffer layer (4) is 1~5nm / min.

8. The preparation method according to claim 6, characterized in that, The conditions for growing Ag-NPs localized surface plasmon modulation layer (3) on the HfO2 buffer layer (4) by ion beam sputtering are as follows: the chamber pressure is pumped to below 5 Pa, the sputtering power is 2~15 W, the sputtering target is Ag target, and the sputtering time is 20~120 s; the sputtered product is annealed to obtain Ag-NPs localized surface plasmon modulation layer (3). The vacuum degree of the annealing process is 10. -1 Below Pa, the temperature is 400~700℃, and the time is 1~5h.

9. The preparation method according to claim 6, characterized in that, The conditions for growing HfO2 capping layer (2) on the surface of Ag-NPs localized surface plasmon modulation layer (3) by pulsed laser deposition are as follows: the target material for deposition is HfO2 target, the oxygen pressure is 0.2~4Pa, the oxygen flow rate is 5~50sccm, the substrate temperature is 150~450℃, the laser frequency is 2~12Hz, and the growth rate of HfO2 capping layer (2) is 1~5nm / min; The conditions for depositing a VO2 thermochromic functional thin film layer (1) on the surface of an HfO2 capping layer (2) using pulsed laser deposition are as follows: the target material used for deposition is a V target, the oxygen pressure is 0.5-3 Pa, the oxygen flow rate is 15-50 sccm, the substrate temperature is 450-550℃, the laser frequency is 1-5 Hz, and the growth rate of the VO2 thermochromic functional thin film layer (1) is 0.6-2.4 nm / min.

10. The application of the HfO2 / Ag-NPs / HfO2 / VO2 composite film as described in any one of claims 1 to 5 in thermochromic smart windows.

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