Colorful structural color film with cooling characteristic

Abstract

The invention discloses a color structural color film with a cooling characteristic. The thin film comprises a plurality of cascaded F-P cavities which are symmetrically arranged, and the specific structure is as follows: (MD) nM (DM) n. Wherein M represents a metal layer, D represents a dielectric layer, and MD and DM represent F-P cavities formed by the metal layer and the dielectric layer. The film system structure adopts an (MD) nM (DM) n (metal layer-dielectric layer-to-metal layer-to-dielectric layer-to-metal layer) symmetrical structure, and the structure is formed by cascading a plurality of F-P cavities. Each F-P cavity is composed of two metal reflectors and a medium layer in the middle, and regulation and control of interference light based on the Fabry-Perot cavity are achieved. The metal material shows high reflection characteristics in visible light and near-infrared bands, can effectively reflect most sunlight, is very useful for reducing heat absorption and improving energy efficiency, and can reduce dependence on an air conditioner and save energy especially in building and automobile coating.

Description

Technical Field

[0001] The invention relates to the technical field of color structural color films, and in particular to a color structural color film with cooling properties. Background Art

[0002] With the increasing demand for environmentally friendly and high-performance materials, people have begun to seek better color rendering methods than traditional chemical dyes. Traditional chemical dyes develop colors by absorbing light of specific wavelengths, but a large amount of harmful chemicals will be produced during production and use, polluting the environment. In contrast, structural colors can effectively overcome the problems brought by traditional chemical dyes. Structural color, also known as physical color, is the color produced by interference or diffraction of light on the surface of an object through the structural features of the surface of an object (such as periodically arranged micro-nano structures or multilayer films, etc.). Among them, structural color thin film devices based on the interference effect of multilayer thin films are the most widely used. This solution does not require the use of more complex process technologies such as photolithography, plasma etching or self-assembly, and is simple to manufacture and suitable for large-scale low-cost commercial production. This color rendering method can show more vivid and stable colors. Therefore, structural color has broad application prospects in display panels, optical detectors, decorative materials, car paints, anti-counterfeiting coatings, color printing and other fields due to its advantages of environmental protection, stability, long life, and scratch resistance.

[0003] For traditional dyes, color is produced simply by absorbing specific wavelengths of incident light and scattering reflections. However, with global warming and rising summer temperatures, such dyes that form colors by absorption will inevitably absorb a large amount of electromagnetic waves from solar radiation, especially in the near-infrared band. After the electromagnetic waves from solar radiation are absorbed by the surface of an object, the light energy is converted into heat energy, generating a certain amount of heat. The solar spectrum is shown in the figure below: Figure 1 For example, car paint or building exterior walls continuously absorb solar radiation under strong sunlight in summer, which increases the temperature inside the car and indoors, thereby increasing the demand for air conditioning, which is not conducive to energy conservation and environmental protection. Therefore, how to effectively manage and reduce this light-to-heat conversion effect and reduce energy consumption has become a problem that needs to be solved urgently.

[0004] In order to solve the above problems, researchers have proposed many improvement methods. For example, in patent CN109291776A, the heat absorption layer of the cooling film (filled with three-dimensional curled cotton or ultra-fine fiber or silk) is placed against the car window, and the heat collection layer (black PVC compressed cloth) gathers the external temperature to the phase change layer, so that the phase change material in the phase change layer is liquefied or vaporized or sublimated to absorb the temperature on one side of the heat absorption layer, thereby cooling the interior of the car.

[0005] The photovoltaic cooling film in the CN217183256U patent is bonded to the photovoltaic cell panel through a backing layer, and then the self-absorption / release performance of the hydrogel layer is used to achieve the purpose of photovoltaic cooling. Both patents are innovative in technology, but both face the problems of complex structure, high cost, environmental impact and difficulty in commercial production. In practical application and commercial promotion, these factors need to be comprehensively considered to find the best balance point to ensure the sustainability and market competitiveness of the product.

[0006] In 2022, Keshun Su et al. made a PVC / photochromic powder composite film by adding photochromic powders of different colors to a PVC substrate, and used its characteristics of changing color and transmittance according to the intensity of sunlight to achieve an intelligent cooling effect. In terms of material selection, chromic powders are sensitive to environmental conditions, and their stability and cost-effectiveness under different conditions must be considered; PVC is a non-degradable material, and it may pose environmental challenges when it is disposed of. It is necessary to select recyclable PVC materials or consider environmental impact management after disposal. In terms of structural design, the design of PVC / photochromic powder composite film involves uniformly covering the surface of PVC with photochromic powder to ensure that it can stably show color change effects under different light intensities. This design usually requires precise process control to ensure uniform distribution and good adhesion of the powder, which leads to high manufacturing costs and process complexity. In summary, although this technology has the advantage of intelligent temperature control, its high cost, complex manufacturing process and environmental impact require comprehensive trade-offs and further technical improvements. Summary of the invention

[0007] In view of this, the purpose of the present invention is to propose a color structural color film with cooling properties. At present, structural color films with cooling functions based on the interference effect of multilayer thin films have not been developed and studied. Considering that this method can not only adjust the color in the visible light range, but also produce high reflection in the near infrared, reduce the temperature of the surface of the object, and achieve cooling effects, it has important application prospects in the fields of coatings, car paints, decorative materials, optical displays, etc.

[0008] According to one aspect of the present invention, a color structural color film with cooling characteristics is provided. The film is a plurality of symmetrically arranged cascaded FP cavities, and the specific structure is as follows:

[0009] (MD)^ n M(DM)^ n

[0010] Wherein, M represents a metal layer, D represents a dielectric layer, MD and DM represent that the metal layer and the dielectric layer constitute a FP cavity.

[0011] In the above technical solution, the membrane structure of the present invention adopts (MD)^ n M(DM)^ n The symmetrical structure of (metal layer-dielectric layer-...-metal layer-...-dielectric layer-metal layer) is composed of several FP cavities in cascade. Each FP cavity is composed of two metal reflectors and a dielectric layer in the middle, which realizes the regulation of interference light based on the Fabry-Perot cavity. Metal materials show high reflectivity in the visible light and near-infrared bands, and can effectively reflect most of the sunlight, which is very useful for reducing heat absorption and improving energy efficiency, especially in construction and automobile painting, which can reduce dependence on air conditioning and save energy. The intermediate transparent dielectric material has high transmittance and is mainly used to adjust the phase and path of light to achieve color tuning. Due to the structure of multi-layer thin films, light waves are reflected multiple times between the metal layer and the dielectric layer, forming an interference phenomenon. The realization of color in this structure is to selectively weaken or eliminate light of a specific wavelength through the interference effect of the multi-layer film, so that the remaining light is highly reflected to form complementary color structural colors such as cyan, magenta, and yellow. Compared with red, green, blue and other reflective color structural colors produced by reflecting light of a single wavelength, complementary color structural colors can reflect electromagnetic waves of solar radiation to a greater extent in the visible light band, and achieve a better cooling effect while meeting color requirements. For example, cyan is achieved by absorbing red light and reflecting green and blue light; magenta is achieved by absorbing green light and reflecting red and blue light; and yellow is achieved by absorbing blue light and reflecting red and green light.

[0012] In some embodiments, at least one layer of AR anti-reflection unit is disposed on the outermost layers on both sides of the film.

[0013] In the above technical solution, the AR anti-reflection units on the outermost sides, i.e., A(MD)^ n M(DM)^ n The A structure better reduces the residual reflection of non-target bands, so that the light of non-target band wavelengths can be weakened or eliminated, and the electromagnetic waves of solar radiation are reflected to a greater extent. While meeting the color requirements, it can better achieve the cooling effect in the visible light band. At the same time, since metal materials show high reflectivity in the near-infrared band, they can also effectively reflect most of the sunlight in the near-infrared band to achieve a cooling effect.

[0014] In some embodiments, the metal layer is made of a metal material with high reflectivity.

[0015] In the above technical solution, the metal material can be selected from gold (Au), silver (Ag), aluminum (Al) and other metals with high reflectivity that can reflect infrared radiation.

[0016] In some embodiments, the material of the dielectric layer is a mixture of one or more of lanthanum titanate, titanium oxide, tantalum oxide, niobium oxide, zirconium oxide, hafnium oxide, yttrium oxide, silicon dioxide, aluminum oxide, zinc sulfide, and magnesium fluoride.

[0017] In the above technical solution, the material selection is mainly based on the optical properties of the material to ensure that the selected material can meet the specific requirements of the dielectric layer in different application scenarios. The optical properties of these materials have been strictly evaluated in order to achieve accurate matching of the dielectric layer performance in different application scenarios.

[0018] In some embodiments, the material of the AR anti-reflection unit is a mixture of one or more of lanthanum titanate, titanium oxide, and silicon dioxide.

[0019] In the above technical solution, the selection of materials is based on their optical properties, including but not limited to reducing surface reflection, enhancing light transmittance, and achieving excellent optical performance. These properties are considered based on a comprehensive evaluation of the performance of the material in the optical system, aiming to achieve effective control of light waves through the optimal selection of materials, thereby meeting the requirements for optical performance in specific applications.

[0020] In some embodiments, the substrate material for growing the colorful structural color film includes: glass, polished stainless steel, polished mirror aluminum, polyethylene terephthalate, cellulose triacetate, polymethyl methacrylate, polycarbonate / polymethyl methacrylate composite material, polyimide, polypropylene, polyvinyl chloride, polyvinyl butyral, ethylene vinyl acetate copolymer, polyurethane elastomer, polytetrafluoroethylene, fluoroethyl propylene, and polyvinyl difluoride.

[0021] In the above technical solutions, each material has its inherent unique advantages, which are crucial to supporting the formation, stability and subsequent processing of thin film structural colors. For example, glass is known for its high transparency, surface flatness and excellent chemical stability, which make it an ideal substrate material for optical applications. Polished stainless steel is favored for its excellent corrosion resistance, surface finish and high strength, which make it excellent in applications requiring corrosion resistance and structural strength. Polyethylene terephthalate (PET) stands out for its high strength, good toughness and excellent processing performance, which give it obvious advantages in applications requiring flexible processing and high toughness requirements. The characteristics of these materials are not only crucial to the realization of thin film structural colors, but also have a significant impact on the long-term stability and processing adaptability of the product.

[0022] In some embodiments, the thickness of the metal layer is 10 nm to 45 nm.

[0023] In the above technical solution, in the field of optical design, the precise setting of the thickness of the metal layer is crucial to achieving high reflectivity in the near-infrared band. The optimization of this parameter is mainly based on the optical behavior of the metal layer in the near-infrared region, aiming to ensure that the designed structure can effectively reflect near-infrared light while meeting specific optical performance requirements. The thickness of the metal layer directly affects its ability to reflect and absorb light of a specific wavelength, which in turn affects the spectral response characteristics of the overall design. Therefore, the setting of the metal layer thickness needs to comprehensively consider the physical properties of the material and the design goals to achieve the best optical performance.

[0024] In some embodiments, the dielectric layer has a thickness of 40 nm to 110 nm.

[0025] In the above technical solution, the thickness of the dielectric layer must be selected to ensure resonance at a specific color wavelength, thereby producing the expected color effect. Specifically, the thickness of the dielectric layer must meet the conditions of optical resonance at the corresponding wavelength, which is based on the interference effect of light waves in the dielectric layer. According to thin film optics theory, the optical thickness of the dielectric layer (i.e., the product of the refractive index and the geometric thickness) is usually set to an integer multiple of one-quarter of the design wavelength to achieve constructive interference, thereby obtaining maximum reflection or transmission at a specific wavelength. By controlling the thickness of the dielectric layer, the position of the optical resonance peak can be adjusted, thereby achieving the generation and regulation of the desired color.

[0026] In some embodiments, the AR anti-reflection unit has a thickness of 10 nm to 65 nm.

[0027] In the above technical solution, the mechanism for setting the thickness of the AR layer is based on the admittance matching principle. The admittance matching principle means that at the interface of the film, by adjusting the optical parameters of the film (such as refractive index and thickness), the admittance (optical impedance) on both sides of the film is matched, thereby reducing the reflection of light waves at the interface. Admittance is the impedance of light waves when propagating in a material, which is related to the refractive index of the material and the wavelength of the light wave. In the AR layer design, by controlling the thickness of the AR anti-reflection unit, admittance matching between the incident medium (such as air) and the substrate material can be achieved. This matching contributes to the smooth transmission of light waves, reduces interface reflections, and thus improves the overall light transmittance performance.

[0028] According to another aspect of the present invention, a method for preparing a color structural color film with cooling properties is provided, which is used to prepare the above-mentioned color structural color film, and the method comprises:

[0029] The method is prepared layer by layer on a substrate by one or more of a physical vapor deposition method, a chemical vapor deposition method, and a pearlescent thin film liquid phase coating method.

[0030] In the above technical solution, a physical vapor deposition (PVD) method is used to prepare the thin film, such as ion beam sputtering deposition (IBS), magnetron sputtering deposition (MS), electron beam evaporation (EB) and a combination of electron beam evaporation + ion assisted deposition (EB + IAD) to prepare the thin film; a chemical vapor deposition (CVD) method and a pearlescent thin film liquid phase coating method can also be used. The above method can accurately control the thickness and quality of the thin film, deposit uniform, dense and high-performance thin films, adapt to multi-layer thin films and gradient refractive index design, and is suitable for a variety of materials and application scenarios, with high deposition efficiency and flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 is a solar spectrum diagram (cited from the prior art);

[0033] Figure 2 It is a schematic structural diagram of a color structural color film with cooling properties having a symmetrical structure according to an embodiment of the present invention;

[0034] Figure 3 This is a reflection spectrum diagram of Example 1 of an embodiment of a color structural color film with cooling characteristics of the present invention in the wavelength range of 400-2000nm and the realized cyan structural color;

[0035] Figure 4 A chromaticity diagram and a chromaticity coordinate value diagram of a cyan structural color are realized in Example 1 of an embodiment of a color structural color film with a cooling property of the present invention;

[0036] Figure 5 A reflection spectrum diagram of Example 2 of an embodiment of a color structural color film with cooling characteristics of the present invention in the wavelength range of 400-2000nm and a schematic diagram of the realized yellow structural color;

[0037] Figure 6 A chromaticity diagram and a schematic diagram of chromaticity coordinate values ​​for realizing yellow structural color in Example 2 of an embodiment of a color structural color film with cooling characteristics of the present invention;

[0038] Figure 7A reflection spectrum diagram of Example 3 of an embodiment of a color structural color film with cooling characteristics of the present invention in the wavelength range of 400-2000nm and a schematic diagram of the realized magenta structural color;

[0039] Figure 8 A chromaticity diagram and a schematic diagram of chromaticity coordinate values ​​for realizing magenta structural color in Example 3 of an embodiment of a color structural color film with cooling characteristics of the present invention;

[0040] Fig. 9 A reflection spectrum diagram of Example 4 of an embodiment of a color structural color film with cooling characteristics of the present invention in the wavelength range of 400-2000nm and a schematic diagram of the realized cyan structural color;

[0041] Fig.10 A chromaticity diagram and a schematic diagram of chromaticity coordinate values ​​for realizing cyan structural color in Example 4 of an embodiment of a color structural color film with cooling characteristics of the present invention;

[0042] Fig.11 A reflection spectrum diagram of Example 5 of an embodiment of a color structural color film with cooling characteristics of the present invention in the wavelength range of 400-2000nm and a schematic diagram of the realized orange structural color;

[0043] Fig.12 A chromaticity diagram and a schematic diagram of chromaticity coordinate values ​​for realizing orange structural color in Example 5 of an embodiment of a color structural color film with cooling characteristics of the present invention;

[0044] Fig.13 A reflection spectrum diagram of Example 6 of an embodiment of a color structural color film with cooling characteristics of the present invention in the wavelength range of 400-2000nm and a schematic diagram of the realized magenta structural color;

[0045] Fig.14 This is a schematic diagram of the chromaticity diagram and chromaticity coordinate values ​​for realizing magenta structural color in Example 6 of an embodiment of a color structural color film with cooling characteristics of the present invention. DETAILED DESCRIPTION

[0046] The present invention will be further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only used to illustrate the present invention, but are not intended to limit the scope of the present invention. Similarly, the following examples are only partial embodiments of the present invention rather than all embodiments, and all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0047] The present invention provides a color structural color film with cooling properties. At present, structural color films with cooling functions based on the interference effect of multilayer films have not been developed and studied. Considering that this method can not only adjust the color in the visible light range, but also produce high reflection in the near infrared, reduce the temperature of the surface of the object, and achieve the cooling effect, it has important application prospects in the fields of coatings, car paints, decorative materials, optical displays, etc.

[0048] Embodiment 1

[0049] See also Figure 2 , a color structural color film with cooling characteristics, the film is a plurality of symmetrically arranged cascaded FP cavities, the specific structure is as follows:

[0050] (MD)^ n M(DM)^ n

[0051] Wherein, M represents a metal layer, D represents a dielectric layer, MD and DM represent that the metal layer and the dielectric layer constitute a FP cavity.

[0052] In this embodiment, at least one layer of AR anti-reflection unit is disposed on the outermost layers on both sides of the film.

[0053] In some embodiments, the metal layer is made of a metal material with high reflectivity.

[0054] In this embodiment, the material of the dielectric layer is a mixture of one or more of lanthanum titanate, titanium oxide, tantalum oxide, niobium oxide, zirconium oxide, hafnium oxide, yttrium oxide, silicon dioxide, aluminum oxide, zinc sulfide, and magnesium fluoride.

[0055] In this embodiment, the material of the AR anti-reflection unit is a mixture of one or more of lanthanum titanate, titanium oxide, and silicon dioxide.

[0056] In this embodiment, the substrate material for growing the colorful structural color film includes: glass, polished stainless steel, polished mirror aluminum, polyethylene terephthalate, cellulose triacetate, polymethyl methacrylate, polycarbonate / polymethyl methacrylate composite material, polyimide, polypropylene, polyvinyl chloride, polyvinyl butyral, ethylene vinyl acetate copolymer, polyurethane elastomer, polytetrafluoroethylene, fluoroethyl propylene, and polyvinyl difluoride.

[0057] In this embodiment, the thickness of the metal layer is 10 nm to 45 nm. The thickness of the dielectric layer is 40 nm to 110 nm. The thickness of the AR anti-reflection unit is 10 nm to 65 nm.

[0058] For better explanation, the present embodiment will be described in detail from the perspective of mechanism, as follows:

[0059] The present invention provides a color structural color film with cooling characteristics. The present invention adopts a symmetrical structure (A(MD)^ n M(DM)^ n A) It achieves high reflection in the target band of visible light (400-700nm), low reflection in the non-target band, and high reflection in the near-infrared band (700-2000nm), such as Figure 1 As shown in the schematic diagram of the thin film structure, M represents the metal film layer material, D represents the dielectric film layer material, A represents the anti-reflection unit, and Sub represents the substrate.

[0060] In the present invention, the metal material can be selected from gold (Au), silver (Ag), aluminum (Al) and other metals with high reflectivity that can reflect infrared radiation. The dielectric material can be selected from lanthanum titanate (LaTiO3), titanium oxide (TiO2), tantalum oxide (Ta2O5), niobium oxide (Nb2O5), zirconium oxide (ZrO2), hafnium oxide (HfO2), yttrium oxide (Y2O3), silicon dioxide (SiO2), aluminum oxide (Al2O3), zinc sulfide (ZnS) or magnesium fluoride (MgF2) and mixtures of the above dielectric materials. The AR anti-reflection unit can be selected from dielectric materials such as lanthanum titanate (LaTiO3), titanium oxide (TiO2), silicon dioxide (SiO2) and mixtures of the above dielectric materials.

[0061] For structural color films used in car paint, anti-counterfeiting ink, industrial coating and other fields, the structural color films can be directly prepared by physical vapor deposition (PVD), chemical vapor deposition (CVD), atomic layer deposition (ALD), sol-gel and other thin film deposition processes. Considering the application requirements, the structure is designed to be a symmetrical structure to ensure that the solar radiation spectrum has the same color development effect and spectrum regulation effect when incident from the front and back incident surfaces of the film, so as to be suitable for any arrangement of the film in inks and coatings.

[0062] The substrate material of the present invention adopts highly polished glass, polished stainless steel, and polished mirror aluminum. According to needs, the substrate can also adopt one of optical plastic substrates such as polyethylene terephthalate (PET), triacetyl cellulose (TAC), polymethyl methacrylate (PMMA), polycarbonate / polymethyl methacrylate composite material (PC / PMMA), polyimide (PI), polypropylene (PP), polyvinyl chloride (PVC), polyvinyl butyral (PVB), ethylene vinyl acetate copolymer (EVA) or polyurethane elastomer (TPU), polytetrafluoroethylene (PTFE), fluoroethyl propylene (FEP), polyvinyl difluoride (PVDF), etc., which is suitable for growing the above-mentioned cooling structural color film on a flexible substrate.

[0063] The film structure of the present invention adopts A(MD)^ n M(DM)^ n A (anti-reflection unit-metal layer-dielectric layer-...-metal layer-...-dielectric layer-metal layer-anti-reflection unit) symmetrical structure, which is composed of several FP cavities in cascade and AR anti-reflection units on both sides. Each FP cavity is composed of two metal reflectors and a dielectric layer in the middle to achieve regulation based on Fabry-Perot cavity interference light. The AR anti-reflection units on both sides can be a single layer or a combination of several layers to better reduce the residual reflection of non-target bands and effectively protect the metal surface from being oxidized by air or chemically corroded. Metal materials show high reflectivity in the visible and near-infrared bands and can effectively reflect most of the sunlight, which is very useful for reducing heat absorption and improving energy efficiency, especially in construction and automobile painting, which can reduce dependence on air conditioning and save energy. The intermediate transparent dielectric material has high transmittance and is mainly used to adjust the phase and path of light to achieve color tuning. Due to the structure of the multilayer film, the light wave is reflected multiple times between the metal layer and the dielectric layer, forming an interference phenomenon. A(MD)^ n M(DM)^ n The realization of color in structure A is to selectively weaken or eliminate light of specific wavelengths through the interference effect of multilayer films, so that the remaining light is highly reflected to form complementary color structural colors such as cyan, magenta, and yellow. Compared with reflective color structural colors such as red, green, and blue that are produced by reflecting light of a single wavelength, complementary color structural colors can reflect electromagnetic waves of solar radiation to a greater extent in the visible light band, while meeting color requirements and achieving a better cooling effect. For example, cyan is achieved by absorbing red light and reflecting green and blue light; magenta is achieved by absorbing green light and reflecting red and blue light; and yellow is achieved by absorbing blue light and reflecting red and green light.

[0064] In (MD)^ n M(DM)^ n In the structure, the thickness of each layer is designed by the interference formula, so that light of a specific wavelength resonates in the cavity, achieving the effect of weakening or eliminating a specific color. The interference formula is as follows:

[0065]

[0066] Where n is the refractive index of the dielectric layer, L is the cavity length (thickness of the dielectric layer), m is the interference order, and λ is the wavelength of light. For a single FP cavity, the free spectral range (FSR) is calculated as:

[0067]

[0068] Where λ is the central wavelength, n is the refractive index of the medium, L is the cavity length (thickness of the dielectric layer), and the line width (Δλ) of the FP cavity is given by Formula 4, where Finesse (F) is a parameter that measures the sharpness of the interference fringes, and its formula is given by Formula 3. Substituting Formulas 2 and 3 into Formula 4, it can be seen from Formula 5 that the higher the reflectivity, the narrower the interference fringes.

[0069]

[0070]

[0071] From the above analysis, it can be seen that in a single FP cavity, the interference line width is very narrow and it is impossible to achieve low reflection in the entire non-target band. Therefore, the main part of the present invention adopts (MD)^ n M(DM)^ n Structure, by cascading multiple FP cavities, can effectively widen the interference bandwidth. For example, there is a five-layer MDMDM structure, which is composed of two FP cavities in cascade, with cavity lengths L1 and L2 respectively, the same medium refractive index n, and the central wavelength λ. For the first FP cavity, its FSR and Δλ are given by formulas 6 and 7, and for the second FP cavity, its FSR and Δλ are given by formulas

[0072] Equations 8 and 9 give:

[0073]

[0074] The total interference bandwidth Δλ of the two FP cavities cascaded is given by formula 10, which can be approximated as the superposition of the interference bandwidths of the single FP cavities. Assuming that the reflectivity and central wavelength of the two cavities are the same, substitute formulas 7 and 9 into formula 10 to obtain the total interference bandwidth:

[0075]

[0076] The above formula shows that the interference bandwidth increases after two FP cavities are cascaded. Since light will experience multiple reflections and transmissions in each cavity when propagating in each cascaded FP cavity, each reflection and transmission will introduce additional phase shifts. These phase shifts accumulate in the entire cascade structure and also lead to an increase in the interference bandwidth. Further, through the AR anti-reflection units on the outermost sides, i.e., A(MD)^ n M(DM)^ n The A structure better reduces the residual reflection of non-target bands, so that the light of non-target band wavelengths can be weakened or eliminated, and the electromagnetic waves of solar radiation are reflected to a greater extent. While meeting the color requirements, it can better achieve the cooling effect in the visible light band. At the same time, since metal materials show high reflectivity in the near-infrared band, they can also effectively reflect most of the sunlight in the near-infrared band to achieve a cooling effect.

[0077] The present invention provides a new structural design, which innovatively uses a symmetrical Fabry-Perot cavity structure to design a color structural color film with cooling characteristics. The present invention has a simple structure, which can not only reduce production costs, but also simplify the production process. In terms of structure, an anti-reflection unit + metal + medium + ... + metal + ... + medium + metal + anti-reflection unit (A(MD)^ n M(DM)^ n A) The combination method achieves high reflection in the target band and low reflection in the non-target band, thereby ensuring that the visible light and near-infrared light in the solar spectrum can be effectively reflected while meeting the diverse color requirements, reducing the surface temperature of the covered object, thereby reducing the internal temperature rise, reducing air conditioning energy consumption, and achieving energy-saving and environmental protection effects. Compared with previous studies, the method proposed in this paper has the advantages of energy saving and environmental protection, simple production process, and easy large-scale production. These advantages make this color structural color film with cooling characteristics have a wide range of application potential in the automotive industry, outdoor equipment, construction and other fields.

[0078] As a further development, six examples will be used to illustrate:

[0079] Example 1

[0080] like Figure 1 As shown, a symmetrical structure color film based on FP cavity is composed of substrate Sub, AR anti-reflection unit A (LaTiO3), metal material M (Ag), dielectric material D (LaTiO3), metal material M (Ag), dielectric material D (LaTiO3), metal material M (Ag), AR anti-reflection unit A (LaTiO3). The AR anti-reflection unit A (LaTiO3), metal material M (Ag) and dielectric material D (LaTiO3) are superimposed to form A (MD)^ 1 M(DM)^ 1 A has a 7-layer symmetrical structure. The specific thickness of each layer is given in Table 1. According to the thickness values ​​given in Table 1, a cyan structural color film with cooling properties can be prepared. Figure 3 The reflection spectrum of Example 1 in the wavelength range of 400-2000nm, as well as the achieved structural color and Lab value, Figure 4The chromaticity coordinate diagram of the realized cyan structural color. In the visible light band of 400-700nm, the target band of 430-536nm has a higher reflectivity (average value of about 88%), and the mixture of the blue light band and the green light band realizes a cyan with a brightness value of L=83. The non-target red light band has a lower reflectivity (average value of about 5%), so that the cyan structural color is finally presented. The chromaticity coordinates of the cyan structural color in this embodiment are (0.21, 0.31). Because it has a higher reflectivity in the near-infrared band of 700-2000nm (average value of about 96%), it can have a cooling effect while presenting a cyan structural color. Compared with reflective structural colors, this embodiment reflects the electromagnetic waves of solar radiation to a greater extent in the visible light band, while meeting the color requirements, it better achieves a cooling effect.

[0081] Table 1 Example 1 Parameters

[0082] Number of layers 1 2 3 4 5 6 7 Material Type <![CDATA[LaTiO3]]> Ag <![CDATA[LaTiO3]]> Ag <![CDATA[LaTiO3]]> Ag <![CDATA[LaTiO3]]> Physical thickness (nm) 15 17 106 31.5 106 17 15

[0083] Example 2

[0084] like Figure 1 As shown, a symmetrical structure color film based on FP cavity is composed of substrate Sub, AR anti-reflection unit A (SiO2), metal material M (Ag), dielectric material D (ZnS), metal material M (Ag), dielectric material D (ZnS), metal material M (Ag), AR anti-reflection unit A (SiO2). The AR anti-reflection unit A (SiO2), metal material M (Ag) and dielectric material D (ZnS) are superimposed to form A (MD)^ 1 M(DM)^ 1 A has a 7-layer symmetrical structure. The specific thickness of each layer is given in Table 2. According to the thickness values ​​given in Table 2, a yellow structural color film with cooling properties can be prepared. Figure 5 The reflection spectrum, structural color and Lab value of Example 2 in the wavelength range of 400-2000nm are shown below. Figure 6The chromaticity coordinate diagram of the realized yellow structural color. In the visible light band of 400-700nm, the target band of 500-700nm has a higher reflectivity (average value of about 92%), and the mixture of the red light band and the green light band realizes the yellow color with a brightness value of L=94. The non-target blue light band has a lower reflectivity (average value of about 2%), so that the final yellow structural color is presented. The chromaticity coordinates of the yellow structural color in this embodiment are (0.42, 0.49). Because it has a higher reflectivity in the near-infrared band of 700-2000nm (average value of about 98%), it can have a cooling effect while presenting a yellow structural color. Compared with reflective structural colors, this embodiment reflects the electromagnetic waves of solar radiation to a greater extent in the visible light band, while meeting the color requirements, it better achieves a cooling effect.

[0085] Table 2 Example 2 Parameters

[0086] Number of layers 1 2 3 4 5 6 7 Material Type <![CDATA[SiO2]]> Ag ZnS Ag ZnS Ag <![CDATA[SiO2]]> Physical thickness (nm) 60 21 52 41 52 21 60

[0087] Example 3

[0088] like Figure 1 As shown, a symmetrical structure color film based on FP cavity is composed of substrate Sub, AR anti-reflection unit A (MgF2), metal material M (Ag), dielectric material D (TiO2), metal material M (Ag), dielectric material D (TiO2), metal material M (Ag), dielectric material D (TiO2), metal material M (Ag), dielectric material D (TiO2), metal material M (Ag), AR anti-reflection unit A (MgF2). The AR anti-reflection unit A (MgF2), metal material M (Ag) and dielectric material D (TiO2) are superimposed to form A (MD)^ 2 M(DM)^ 2 A has an 11-layer symmetrical structure. The specific thickness of each layer is given in Table 3. According to the thickness values ​​given in Table 3, a magenta structural color film with cooling properties can be prepared. Figure 7 The reflection spectrum, structural color and Lab value of Example 3 in the wavelength range of 400-2000nm are shown below. Figure 8The chromaticity coordinate diagram of the realized magenta structural color. In the visible light band 400-700nm band, the blue light band 400-445nm band has a higher reflectivity (average value of about 90%), and the red light band 640-700nm band has a higher reflectivity (average value of about 85%), achieving high reflection of the target band. The mixture of the blue light band and the red light band realizes the magenta color with a brightness value of L=49. The non-target green light band has a lower reflectivity (average value of about 6%), so that the magenta structural color is finally presented. The chromaticity coordinates of the magenta structural color in this embodiment are (0.32, 0.15). In addition, since the near-infrared band 700-2000nm band has a higher reflectivity (average value of about 96%), it can have a cooling effect while presenting the magenta structural color. Compared with the reflective structural color, this embodiment reflects the electromagnetic waves of solar radiation to a greater extent in the visible light band, while meeting the color requirements, it better achieves the cooling effect.

[0089] Table 3 Example 3 Parameters

[0090] Number of layers 1 2 3 4 5 6 7 8 9 10 11 Material Type <![CDATA[MgF2]]> Ag <![CDATA[TiO2]]> Ag <![CDATA[TiO2]]> Ag <![CDATA[TiO2]]> Ag <![CDATA[TiO2]]> Ag <![CDATA[MgF2]]> Physical thickness (nm) 44 12 50 24 79 12 79 24 50 12 44

[0091] Example 4

[0092] like Figure 1 As shown, a symmetrical structure color film based on FP cavity is composed of substrate Sub, AR anti-reflection unit A (LaTiO3), metal material M (Ag), dielectric material D (Ta2O5), metal material M (Al), dielectric material D (Ta2O5), metal material M (Ag), AR anti-reflection unit A (LaTiO3). The AR anti-reflection unit A (LaTiO3), metal material M (Ag), metal material M (Al) and dielectric material D (Ta2O5) are superimposed to form A (MD)^ 1 M(DM)^ 1 A has a 5-layer symmetrical structure. The specific thickness of each layer is given in Table 4. According to the thickness values ​​given in Table 4, a cyan structural color film with cooling properties can be prepared. Fig. 9 The reflection spectrum, structural color and Lab value of Example 4 in the wavelength range of 400-2000nm are shown below. Fig.10The chromaticity coordinate diagram of the realized magenta structural color. In the visible light band of 400-700nm, the target band of 430-540nm has a higher reflectivity (average value of about 84%), and the mixture of the blue light band and the green light band realizes the cyan color with a brightness value of L=84. The non-target red light band has a lower reflectivity (average value of about 8%), so that the cyan structural color is finally presented. The chromaticity coordinates of the cyan structural color in this embodiment are (0.23, 0.32). Because it has a higher reflectivity in the near-infrared band of 700-2000nm (average value of about 92%), it can have a cooling effect while presenting the cyan structural color. Compared with the reflective structural color, this embodiment reflects the electromagnetic waves of solar radiation to a greater extent in the visible light band, while meeting the color requirements, it better achieves the cooling effect.

[0093] Table 4 Example 4 Parameters

[0094] Number of layers 1 2 3 4 5 6 7 Material Type <![CDATA[LaTiO3]]> Ag <![CDATA[Ta2O5]]> Al <![CDATA[Ta2O5]]> Ag <![CDATA[LaTiO3]]> Physical thickness (nm) 15 16 108 13 108 16 15

[0095] Example 5

[0096] like Figure 1 As shown, a symmetrical structure color film based on FP cavity is composed of substrate Sub, AR anti-reflection unit A (MgF2), metal material M (Au), dielectric material D (MgF2), metal material M (Au), dielectric material D (MgF2), metal material M (Au), AR anti-reflection unit A (MgF2). The AR anti-reflection unit A (MgF2), metal material M (Au) and dielectric material D (MgF2) are superimposed to form A (MD)^ 1 M(DM)^ 1 A has a 7-layer symmetrical structure. The specific thickness of each layer is given in Table 5. According to the thickness values ​​given in Table 5, an orange structural color film with cooling properties can be prepared. Fig.11 The reflection spectrum, structural color and Lab value of Example 4 in the wavelength range of 400-2000nm are shown below. Fig.12 The chromaticity coordinate diagram of the realized orange structural color. In the visible light band of 400-700nm, a small part of green light and red light are mixed and superimposed to realize an orange structural color with a brightness value of L=57. The non-target blue light band has a lower reflectivity (the average value is about 0.7%), so that the final magenta orange structural color is presented. The chromaticity coordinates of the orange structural color in this embodiment are (0.55, 0.44). And because it has a higher reflectivity in the near-infrared band of 700-2000nm (the average value is about 94%), it can have a cooling effect while presenting the orange structural color. Compared with reflective structural colors such as RGB, this embodiment reflects the electromagnetic waves of solar radiation to a greater extent in the visible light band, while meeting the color requirements, it better achieves the cooling effect.

[0097] Table 5 Example 5 Parameters

[0098] Number of layers 1 2 3 4 5 6 7 Material Type <![CDATA[MgF2]]> Au <![CDATA[MgF2]]> Au <![CDATA[MgF2]]> Au <![CDATA[MgF2]]> Physical thickness (nm) 47 12 68 23 68 12 47

[0099] Example 6

[0100] like Figure 1 As shown, a symmetrically structured color film based on the FP cavity is composed of a substrate Sub, an AR anti-reflection unit A (MgF2), a metal material M (Au), a dielectric material D (TiO2), a metal material M (Au), a dielectric material D (TiO2), a metal material M (Au), a dielectric material D (TiO2), a metal material M (Au), a dielectric material D (TiO2), a metal material M (Au), and an AR anti-reflection unit A (MgF2). The AR anti-reflection unit A (MgF2), the metal material M (Au) and the dielectric material D (TiO2) are superimposed to form A (MD)^ 2 M(DM)^ 2 A has an 11-layer symmetrical structure. The specific thickness of each layer is given by 7. According to the thickness values ​​given in Table 7, a magenta structural color film with cooling properties can be prepared. Fig.13 The reflection spectrum, structural color and Lab value of Example 4 in the wavelength range of 400-2000nm are shown below. Fig.14 The chromaticity coordinate diagram of the realized magenta structural color. In the visible light band of 400-700nm, the blue light and red light bands are mixed and superimposed to realize a magenta color with a brightness value of L=36. The non-target green light band has a lower reflectivity (average value of about 1%), so that the final magenta structural color is presented. The chromaticity coordinates of the magenta structural color in this embodiment are (0.32, 0.15). Because it has a higher reflectivity in the near-infrared band of 700-2000nm (average value of about 95%), it can have a cooling effect while presenting the magenta structural color. Compared with reflective structural colors such as RGB, this embodiment reflects the electromagnetic waves of solar radiation to a greater extent in the visible light band, while meeting the color requirements, it better achieves a cooling effect.

[0101] Table 6 Example 6 Parameters

[0102] Number of layers 1 2 3 4 5 6 7 8 9 10 11 Material Type <![CDATA[LaTiO3]]> Au <![CDATA[TiO2]]> Au <![CDATA[TiO2]]> Au <![CDATA[TiO2]]> Au <![CDATA[TiO2]]> Au <![CDATA[LaTiO3]]> Physical thickness (nm) 50 32 63 42 84 8 84 42 63 32 50

[0103] Embodiment 2

[0104] In this specific implementation, the above examples are all about preparing thin films by physical vapor deposition (PVD), such as ion beam sputtering deposition (IBS), magnetron sputtering deposition (MS), electron beam evaporation (EB), and electron beam evaporation + ion assisted deposition (EB + IAD) combined methods; chemical vapor deposition (CVD) methods and pearlescent thin film liquid phase coating methods can also be used. Taking the thin film of Example 1 as an example, the specific method includes the following steps:

[0105] S1: placing a flat surface object as a substrate in a film forming equipment chamber; cleaning and pre-treating the surface of the substrate SUB in a reaction chamber to remove surface contaminants; the cleaning method adopts one of ion bombardment or high temperature baking;

[0106] S2: depositing an AR anti-reflection unit A (LaTiO3) on the upper surface of the substrate SUB; the deposition method adopts one of physical vapor deposition (PVD) and chemical vapor deposition (CVD);

[0107] S3: depositing a metal material M (Ag) on ​​the upper surface of the metal reflective material film layer M; the deposition method is one of physical vapor deposition (PVD) and chemical vapor deposition (CVD);

[0108] S4: depositing a dielectric material D (LaTiO3) on the upper surface of the dielectric layer D; the deposition method adopts one of physical vapor deposition (PVD) and chemical vapor deposition (CVD);

[0109] S5: depositing a metal material M (Ag) on ​​the upper surface of the metal layer M; the deposition method adopts one of physical vapor deposition (PVD) and chemical vapor deposition (CVD);

[0110] S6: depositing a dielectric material D (LaTiO3) on the upper surface of the dielectric layer D; the deposition method adopts one of physical vapor deposition (PVD) and chemical vapor deposition (CVD);

[0111] S7: depositing a metal material M (Ag) on ​​the upper surface of the metal layer M; the deposition method adopts one of physical vapor deposition (PVD) and chemical vapor deposition (CVD);

[0112] S8: depositing an AR anti-reflection unit A (LaTiO3) on the upper surface of the metal layer M; the deposition method adopts one of physical vapor deposition (PVD) or chemical vapor deposition (CVD).

[0113] The above descriptions are only some embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any equivalent device or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A color structural color film with cooling properties, characterized in that: The film is a plurality of symmetrically arranged cascaded FP cavities, and the specific structure is as follows: (MD)^ n M(DM)^ n Wherein, M represents a metal layer, D represents a dielectric layer, MD and DM represent that the metal layer and the dielectric layer constitute a FP cavity.

2. A color structural color film with cooling properties as claimed in claim 1, characterized in that: The outermost layers on both sides of the film are each provided with at least one layer of AR anti-reflection unit.

3. A color structural color film with cooling properties as claimed in claim 1, characterized in that: The material of the metal layer is a metal material with high reflectivity.

4. A color structural color film with cooling properties as claimed in claim 1, characterized in that: The material of the dielectric layer is a mixture of one or more of lanthanum titanate, titanium oxide, tantalum oxide, niobium oxide, zirconium oxide, hafnium oxide, yttrium oxide, silicon dioxide, aluminum oxide, zinc sulfide, and magnesium fluoride.

5. A color structural color film with cooling properties as claimed in claim 2, characterized in that: The material of the AR anti-reflection unit is a mixture of one or more of lanthanum titanate, titanium oxide and silicon dioxide.

6. A color structural color film with cooling properties as claimed in claim 1, characterized in that: The substrate materials for growing the colorful structural color film include: glass, polished stainless steel, polished mirror aluminum, polyethylene terephthalate, cellulose triacetate, polymethyl methacrylate, polycarbonate / polymethyl methacrylate composite material, polyimide, polypropylene, polyvinyl chloride, polyvinyl butyral, ethylene vinyl acetate copolymer, polyurethane elastomer, polytetrafluoroethylene, fluoroethyl propylene, and polyvinyl difluoride.

7. A color structural color film with cooling properties as claimed in claim 1, characterized in that: The thickness of the metal layer is 10nm-45nm.

8. The color structural color film with cooling property as claimed in claim 1, characterized in that: The thickness of the dielectric layer is 40nm-110nm.

9. A color structural color film with cooling properties as claimed in claim 2, characterized in that: The thickness of the AR anti-reflection unit is 10nm-65nm.

10. A method for preparing a color structural color film with cooling properties, characterized in that: For preparing a color structural color film according to any one of claims 1 to 9, the method comprises: The method is prepared layer by layer on a substrate by one or more of a physical vapor deposition method, a chemical vapor deposition method, and a pearlescent thin film liquid phase coating method.

Images