Color cooling optical film based on composite multivariate film layer structure and preparation method

Abstract

The application discloses a color cooling optical thin film based on a composite multilayer film structure and a preparation method thereof. m F'', wherein R is a lossy metal layer, F' is a first composite lossless dielectric layer, and F'' is a second composite lossless dielectric layer; a mirror multilayer film layer is arranged on the multilayer film layer and has a structure of F'' T (RF' T ) m , wherein F'' T is symmetrical with a film layer material arrangement order of F'', F' T is symmetrical with a film layer material arrangement order of F', and thicknesses of the film layers in the mirror multilayer film layer are not completely same as thicknesses of the corresponding film layers in the multilayer film layer; the multilayer film layer and the mirror multilayer film layer form a symmetrical composite film system, the symmetrical composite film system constitutes a Fabry-Perot cavity structure, is used for generating a reflection structural color in a visible light wave band, and realizes high reflectivity in a 0.8-2.5 mu m near-infrared wave band. The application realizes color and cooling effects.

Description

Technical Field

[0001] This invention relates to the field of optical thin film technology, and in particular to a color cooling optical thin film based on a composite multi-layer film structure and its preparation method. Background Technology

[0002] As the greenhouse effect intensifies, the global demand for cooling is becoming increasingly urgent, leading to the consumption of large amounts of fossil fuels annually and further exacerbating the energy crisis. To address this challenge, researchers are dedicated to finding a green and environmentally friendly cooling technology. Radiative cooling, as a novel cooling method, has attracted widespread attention. By modulating the solar spectrum (achieving high reflectivity in the 0.3-2.5μm range) and the atmospheric transparency window range (achieving high emissivity in the 8-13μm range), passive cooling of objects can be achieved without external energy input. It is currently widely used in building exteriors, automotive paint, smart windows, and other fields.

[0003] Traditional daytime radiative cooling technology achieves high reflectivity in the 0.3-2.5μm wavelength range to effectively block the absorption of solar radiation energy, and high emissivity in the 8-13μm wavelength range (highly transparent to electromagnetic waves) to radiate its own heat through the atmospheric window into the cold outer space (3K). However, the visible light band (0.4-0.8μm) also falls within the 0.3-2.5μm wavelength range. The high reflectivity in this band makes objects appear silvery-white, causing severe light pollution under daytime sunlight, and the monotonous color lacks aesthetic value. Based on this, researchers have proposed colored radiative cooling. By controlling the spectrum in the 0.4-0.8μm wavelength range, the desired color can be obtained. High reflectivity is still maintained in the near-infrared band (0.8-2.5μm), and high emissivity is maintained in the 8-13μm wavelength range. Multi-band control ensures vibrant colors for objects while also providing a cooling effect.

[0004] Currently, colored radiative cooling can be achieved through various forms such as optical thin films, polymer thin films, and metamaterials. Chinese patent CN117416115B proposes a double-layer colored radiative cooling coating combining a transparent composite film with a barium sulfate / hollow structure dielectric microsphere substrate, achieving a maximum solar reflectivity of 98.13% and an infrared emissivity of 98.5%, balancing high cooling power with the presentation of different colors and overcoming the heat absorption defects of pigments. Chinese patent CN110109204B discloses a colored radiative cooler based on a Tamm resonance structure, utilizing distributed Bragg mirrors and metal film coupling to generate Tamm resonance, achieving thin film structural color, and coupling it with a selective emitter to achieve subtractive three-primary-color radiative cooling.

[0005] However, existing research requires thicker materials to achieve high emissivity in atmospheric transparent windows, resulting in complex and costly fabrication processes unsuitable for large-scale production. Furthermore, thicker films can cause spectral line shape disturbances in the visible light band, severely impacting color saturation. Currently, commercially available colored coatings are absorption colors, often absorbing significant amounts of solar radiation energy in the near-infrared band, leading to substantial surface temperature increases. Color-controlled cooling technology, by adjusting the visible light band (0.4-0.8 μm for vibrant color spectral line shapes) and the near-infrared band (0.8-2.5 μm for high reflectivity), can achieve cooling effects far lower than commercially available coatings of the same color under sunlight conditions. Moreover, since color-controlled cooling technology does not require consideration of the atmospheric transparent window band, it requires thinner materials, effectively reducing fabrication difficulty and significantly lowering costs. Therefore, designing a color-controlled cooling method with good color performance, adjustable color, and simple fabrication will greatly promote the development of future passive cooling technologies. Summary of the Invention

[0006] In view of this, the purpose of this invention is to propose a colored cooling optical film based on a composite multi-layer film structure. This film adopts a composite multi-layer film structure, has a high-purity, color-tunable reflective structural color, and has high reflectivity in the near-infrared band of 0.8-2.5μm, thereby achieving excellent cooling effect.

[0007] To achieve the above-mentioned technical objectives, the technical solution adopted by this invention is as follows: This invention provides a color cooling optical thin film based on a composite multi-layer film structure, the thin film comprising: A multi-element membrane layer, wherein the structure of the multi-element membrane layer is (F'R). m F'', where R is the lossy metal layer, F' is the first composite lossless dielectric layer formed by stacking multiple lossless dielectric layers from bottom to top, F'' is the second composite lossless dielectric layer formed by stacking multiple lossless dielectric layers from bottom to top, m is the number of repeated stacking, and m≥1; A mirror-image multi-element film layer disposed on the multi-element film layer, the structure of the mirror-image multi-element film layer being F'' T (RF) T ) m , where F'' T The arrangement order of the film materials is symmetrical with that of F''. T The arrangement of the film materials is symmetrical with respect to F', and the thickness of each film layer in the mirror-image multi-element film layer is not exactly the same as the thickness of the corresponding film layer in the multi-element film layer; The multi-element film layer and the mirror multi-element film layer form a symmetrical composite film system. The symmetrical composite film system constitutes a Fabry-Perot cavity structure, which is used to generate reflective structural colors in the visible light band and achieve high reflectivity in the 0.8–2.5 μm near-infrared band.

[0008] Furthermore, the (F'R) in the multi-element film layer m The structure is F1'R1F2'R2…F m 'R m Among them, F1', F2'...F m 'F' is the first composite lossless dielectric layer with the same or different structures, R1, R2...R m The damaged metal layer can be made of the same or different materials; the (RF') in the mirrored multi-element film layer T ) m The structure is R m F m ' T …R2F2' T R1F1' T .

[0009] Furthermore, the first composite non-destructive dielectric layer F' structure in the multi-element film layer is formed by stacking n non-destructive dielectric layers F from bottom to top, specifically F 11 F 12 …F 1n , of which F 11 F 12 …F 1n The non-destructive dielectric layer F can be made of different or the same material; the second composite non-destructive dielectric layer F'' in the multi-element film layer is composed of p non-destructive dielectric layers F stacked from bottom to top, specifically F 21 F 22 …F 2p , of which F 21 F 22 …F 2p F is a non-destructive dielectric layer made of different or the same material; F'' in the mirror-image multi-element film layer T The structure is F 2p …F 22 F 21 F' in the mirror-image multi-element film layer T The structure is F 1n …F 12 F 11 , where n and p are the number of times the stack is repeated, and n≥1, p≥1.

[0010] Furthermore, the multi-element film layer and the mirror-image multi-element film layer are connected by F'' and F'' T The adjacent layers form a symmetrical composite dielectric layer structure F''F'' TWhen p≥2, F'' and F'' T Adjacent settings, where F'' is F 21 F 22 …F 2p , F'' T For F 2p …F 22 F 21 two adjacent F 2p The membrane materials are the same, and they are merged into one layer to form a symmetrical membrane structure F. 21 F 22 …F 2p …F 22 F 21 .

[0011] Furthermore, the material of the non-destructive dielectric layer F has a refractive index of 1.2-5 and an extinction coefficient of 0-1 in the wavelength range of 380nm-780nm. The material of the non-destructive dielectric layer F is selected from at least one of MgF2, LaTiO3, SiO2, Ta2O5, TiO2, HfO2, Al2O3 and Si. The thickness of the non-destructive dielectric layer F ranges from 20nm to 1000nm.

[0012] Furthermore, the material of the damaged metal layer R is selected from at least one of Au, Cu, Ag, Al, Ni, Cr, Ti and W, and the thickness of the damaged metal layer R ranges from 1 nm to 200 nm.

[0013] Furthermore, the thickness range of the non-destructive dielectric layer F is 20nm-800nm, and the thickness range of the destructive metal layer R is 1nm-60nm.

[0014] This invention also provides a method for preparing a color cooling optical thin film based on a composite multi-layer film structure. This method requires providing a color cooling optical thin film based on a composite multi-layer film structure as described above, and includes the following steps: Step 1: Provide a substrate and clean the substrate. Step 2: Place the cleaned substrate in the vacuum coating equipment; Step 3: Sequentially deposit each of the multi-layer films on the substrate, including the first composite non-destructive dielectric layer F', the destructive metal layer R, and the second composite non-destructive dielectric layer F'', to form (F'R). m F'' structure, where R is a lossy metal layer, F' is a first composite lossless dielectric layer formed by stacking multiple lossless dielectric layers from bottom to top, F'' is a second composite lossless dielectric layer formed by stacking multiple lossless dielectric layers from bottom to top, m is the number of repeated stacking, and m≥1; Step 4: Sequentially deposit each layer of the mirror-image multi-layer film on the multi-layer film, including F''T and (RF' T ) m , forming F'' T (RF) T ) m Structure, where F'' T The arrangement order of the film materials is symmetrical with that of F''. T The arrangement of the film materials is symmetrical with respect to F', and the thickness of each film layer in the mirror-image multi-element film layer is not exactly the same as the thickness of the corresponding film layer in the multi-element film layer; Step 5: After deposition is complete, cool and remove the film.

[0015] Furthermore, the substrate material is selected from 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, or polydifluoroethylene.

[0016] Furthermore, the feature is that in steps 3 and 4, each layer of the multi-element film layer is sequentially deposited on the substrate using physical vapor deposition, chemical vapor deposition, or pearlescent thin film liquid phase coating, and each layer of the mirror-image multi-element film layer is sequentially deposited on the multi-element film layer. The physical vapor deposition method includes ion beam sputtering deposition, magnetron sputtering deposition, electron beam evaporation, atomic layer deposition, or electron beam evaporation ion-assisted deposition. If the non-destructive dielectric layer is made of oxide material, oxygen needs to be introduced during the deposition process.

[0017] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art: 1. This invention is based on a composite multi-layer film structure. Due to the interaction between the two modules, the multi-layer film and the mirror multi-layer film, a highly saturated complementary color display can be obtained, with high color purity, wide color gamut, and excellent color performance.

[0018] 2. It is easy to prepare and has low cost. There is no need to consider the disturbance of the visible light spectrum line shape caused by the 8-13μm thick film layer. Moreover, due to its high reflectivity in the near-infrared region, it still has excellent cooling effect compared with similar products on the market.

[0019] 3. It can be designed as a structure with symmetrical film material and thickness. After the film is peeled off, it is prepared as a coating and applied to the surface of automobiles, buildings and other facilities by spraying or other means. It is not limited by coating equipment and the shape and size of the workpiece, and has a wide range of applications. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0021] Figure 1 This is a schematic diagram of the membrane structure of a colored cooling film based on a composite multi-layer membrane structure according to the present invention.

[0022] Figure 2 This is a schematic diagram of the first composite non-destructive dielectric layer F' of a colored cooling film based on a composite multi-layer film structure according to the present invention.

[0023] Figure 3 This is a schematic diagram of the second composite non-destructive dielectric layer F'' of a colored cooling film based on a composite multi-layer film structure according to the present invention.

[0024] Figure 4 This is a reflection spectrum of a colored cooling film based on a composite multi-layer film structure according to the present invention, in the 400nm-2500nm band under vertical incidence.

[0025] Figure 5 This is a chromaticity coordinate diagram under vertical incidence for one embodiment of a colored cooling film based on a composite multi-layer film structure according to the present invention.

[0026] Figure 6 This is a reflection spectrum of a second embodiment of a colored cooling film based on a composite multi-layer film structure of the present invention in the 400nm-2500nm band under vertical incidence.

[0027] Figure 7 This is a chromaticity coordinate diagram under vertical incidence, representing a second embodiment of a colored cooling film based on a composite multi-layer film structure according to the present invention.

[0028] Figure 8 This is a reflection spectrum of a third embodiment of a colored cooling film based on a composite multi-layer film structure of the present invention in the 400nm-2500nm band under vertical incidence.

[0029] Figure 9 This is a chromaticity coordinate diagram under vertical incidence, representing a third embodiment of a colored cooling film based on a composite multi-layer film structure according to the present invention.

[0030] Figure 10 This is a reflection spectrum of a fourth embodiment of a colored cooling film based on a composite multi-layer film structure of the present invention, in the 400nm-2500nm band under vertical incidence.

[0031] Figure 11 This is a chromaticity coordinate diagram under vertical incidence, representing a fourth embodiment of a colored cooling film based on a composite multi-layer film structure according to the present invention. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be particularly noted that the following embodiments are for illustrative purposes only and do not limit the scope of the invention. Similarly, the following embodiments are only some, not all, embodiments of the present invention, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Please see Figures 1-11 The present invention discloses a color cooling optical thin film based on a composite multi-layer film structure, the thin film comprising: A multi-element film layer A, wherein the structure of the multi-element film layer is (F'R). m F'', where R is the lossy metal layer, F' is the first composite lossless dielectric layer formed by stacking multiple lossless dielectric layers from bottom to top, F'' is the second composite lossless dielectric layer formed by stacking multiple lossless dielectric layers from bottom to top, m is the number of repeated stacking, and m≥1; A mirror-image multi-element film layer A disposed on the multi-element film layer T The structure of the mirror-image multi-element film layer is F'' T (RF) T ) m , where F'' T The arrangement order of the film materials is symmetrical with that of F''. T The arrangement of the film materials is symmetrical to that of F', and the thickness of each film layer in the mirror-image multi-element film layer is not exactly the same as the thickness of the corresponding film layer in the multi-element film layer; here, the superscript T indicates a structure symmetrical to the original film layer structure, such as (F1F2F3). T =F3F2F1, but only the material arrangement is symmetrical, and the corresponding film thickness is not completely consistent.

[0034] The multi-element membrane layer and the mirror-image multi-element membrane layer form a symmetrical composite membrane system (F'R). m F''F'' T (RF) T ) m The symmetrical composite film system constitutes a Fabry-Perot cavity structure, which is used to generate reflective structural colors in the visible light band and achieve high reflectivity in the 0.8–2.5 μm near-infrared band.

[0035] In this embodiment, (F'R) in the multi-element film layer m The structure is F1'R1F2'R2…Fm 'R m Among them, F1', F2'...F m 'F' is the first composite lossless dielectric layer with the same or different structures, R1, R2...R m The damaged metal layer can be made of the same or different materials; the (RF') in the mirrored multi-element film layer T ) m The structure is R m F m ' T …R2F2' T R1F1' T .

[0036] In this embodiment, the first composite non-destructive dielectric layer F' structure in the multi-element film layer is formed by stacking n non-destructive dielectric layers F from bottom to top, i.e., F n Specifically, F 11 F 12 …F 1n , of which F 11 F 12 …F 1n The non-destructive dielectric layer F can be made of different or the same material; the second composite non-destructive dielectric layer F'' in the multi-element film layer is composed of p non-destructive dielectric layers F stacked from bottom to top, i.e., F p Specifically, F 21 F 22 …F 2p , of which F 21 F 22 …F 2p F is a non-destructive dielectric layer made of different or the same material; F'' in the mirror-image multi-element film layer T The structure is F 2p …F 22 F 21 F' in the mirror-image multi-element film layer T The structure is F 1n …F 12 F 11 , where n and p are the number of times the stack is repeated, and n≥1, p≥1.

[0037] In this embodiment, the multi-element film layer and the mirror multi-element film layer are connected by F'' and F''. T The adjacent layers form a symmetrical composite dielectric layer structure F''F'' T When p≥2, F'' and F'' T Adjacent settings, where F'' is F 21 F 22 …F 2p , F'' T For F 2p …F22 F 21 two adjacent F 2p The membrane materials are the same, and they are merged into one layer to form a symmetrical membrane structure F. 21 F 22 …F 2p …F 22 F 21 .

[0038] In this embodiment, the material of the non-destructive dielectric layer F has a refractive index of 1.2-5 and an extinction coefficient of 0-1 in the wavelength range of 380nm-780nm. The material of the non-destructive dielectric layer F is selected from at least one of MgF2, LaTiO3, SiO2, Ta2O5, TiO2, HfO2, Al2O3 and Si. The thickness of the non-destructive dielectric layer F ranges from 20nm to 1000nm.

[0039] In this embodiment, the material of the damaged metal layer R is selected from at least one of Au, Cu, Ag, Al, Ni, Cr, Ti and W, and the thickness of the damaged metal layer R ranges from 1 nm to 200 nm.

[0040] In this embodiment, the thickness of the non-destructive dielectric layer F ranges from 20nm to 800nm, and the thickness of the destructive metal layer R ranges from 1nm to 60nm.

[0041] The characteristic matrix of a lossless dielectric monolayer thin film is: (1) For lossless dielectric layers and For real numbers, and It is a purely imaginary number, and = , =1.

[0042] The characteristic matrix of a multilayer film is the product of the characteristic matrices of each single-layer film, that is: (2) When the number of repeated stackings p is 2, the simplest symmetric membrane structure F1F2F1 can be obtained, and its characteristic matrix is: (3) The solution is: (4) (5) (6) (7) Since the characteristic matrix properties of symmetric film systems FRF and monolayer films are the same, they can be described by a special equivalent monolayer film: (8) (9) (10) Similarly, when the number of repeated stacking p is greater than 2, F ’’ F ’’T Similarly, it can be equivalent to a special single-layer membrane. Here, the composite multi-layer membrane structure (F) is used. ’ R) ^m F ’’ F ’’T (RF ’T ) ^m Considered as ①(F) ’ R) ^m 、②F ’’ F ’’T 、③(RF ’T ) ^m The three parts are: ① and ③ are approximately two metal mirrors, and ② is equivalent to a single layer of lossless medium film. The three parts work together to form a special Fabry-Perot cavity, which can widen the reflection valley and increase color saturation.

[0043] When achieving the cooling function, the cooling device operates at an ambient air temperature of T. amb When the temperature is T, its cooling power density is: (11) In the formula, The radiative power density of a cooling device is defined as: (12) In equation (12) Angle integral calculation for a hemispherical region The emissivity of the radiation-cooled thin film. Indicates temperature as The blackbody radiation spectrum is defined as: (13) In equation (13), Let be Planck's constant. The speed of light in a vacuum. Boltzmann's constant, For wavelength, The absorbed power density caused by incident atmospheric thermal radiation is defined as: (14) Since the cooling device only considers spectral modulation in the visible and near-infrared bands, and Defined as a constant, For radiation cooling device and external environment Nonradiative heat exchange between The power density of the commutation is defined as: (15) In equation (15) This is a coefficient representing the degree of non-radiative heat exchange, including convection and conduction. Since the effects of heat convection and heat conduction are relatively constant when the cooling device is exposed to the outside air, therefore... It is also defined as a constant. The solar energy absorption power density in the range of 0.3 - 2.5 μm is defined as follows: (16) In equation (16), Given the solar irradiance (0.3-2.5 μm), therefore, to maximize the cooling power density... It can be reduced It is found that when it exhibits high reflectivity and low emissivity in the near-infrared region... Get the desired result.

[0044] This invention also provides a method for preparing a color cooling optical thin film based on a composite multi-layer film structure. This method requires providing a color cooling optical thin film based on a composite multi-layer film structure as described above, and includes the following steps: Step 1: Provide a substrate and clean the substrate. In this embodiment, the substrate material is selected from glass, polished stainless steel, polished mirror aluminum, polyethylene terephthalate (PET), cellulose triacetate (TAC), polymethyl methacrylate (PMMA), polycarbonate / polymethyl methacrylate composite (PC / PMMA), polyimide (PI), polypropylene (PP), polyvinyl chloride (PVC), polyvinyl butyral (PVB), ethylene vinyl acetate copolymer (EVA), polyurethane elastomer (TPU), polytetrafluoroethylene (PTFE), fluoroethyl propylene (FEP), or polyvinyl difluoroethylene (PVDF).

[0045] Step 2: Place the cleaned substrate in the vacuum coating equipment; Step 3: Sequentially deposit each of the multi-layer films on the substrate, including the first composite non-destructive dielectric layer F', the destructive metal layer R, and the second composite non-destructive dielectric layer F'', to form (F'R). mF'' structure, where R is a lossy metal layer, F' is a first composite lossless dielectric layer formed by stacking multiple lossless dielectric layers from bottom to top, F'' is a second composite lossless dielectric layer formed by stacking multiple lossless dielectric layers from bottom to top, m is the number of repeated stacking, and m≥1; Step 4: Sequentially deposit each layer of the mirror-image multi-layer film on the multi-layer film, including F'' T and (RF' T ) m , forming F'' T (RF) T ) m Structure, where F'' T The arrangement order of the film materials is symmetrical with that of F''. T The arrangement of the film materials is symmetrical with respect to F', and the thickness of each film layer in the mirror-image multi-element film layer is not exactly the same as the thickness of the corresponding film layer in the multi-element film layer; Step 5: After deposition is complete, cool and remove the film.

[0046] In this embodiment, steps 3 and 4 employ physical vapor deposition (PVD), chemical vapor deposition (CVD), or pearlescent thin film liquid phase coating to sequentially deposit each layer of the multi-element film layer on the substrate, and to sequentially deposit each layer of the mirror-image multi-element film layer on the multi-element film layer. The physical vapor deposition method includes ion beam sputtering deposition (IBS), magnetron sputtering deposition (MS), electron beam evaporation (EB), atomic layer deposition (ALD), or electron beam evaporation ion-assisted deposition (EBD-IAD). If the non-destructive dielectric layer is made of oxide material, oxygen needs to be introduced during the deposition process.

[0047] This invention employs electron beam evaporation ion-assisted deposition (EBD-IAD) to prepare thin films. The specific preparation process is as follows: S1. Remove the substrate from which the thin film was deposited; S2. Wipe it clean with a mixture of alcohol and acetone in a 3:1 ratio; S3. Seal the cleaned substrate in a dust-free environment and remove it before coating to avoid secondary contamination; S4. Prepare the materials to be coated and put them into the corresponding crucibles. Ag and Al need to be put into molybdenum crucibles or evaporation boats for resistance evaporation, SiO2 into ring crucibles, Cu into graphite crucibles, and other non-destructive media and destructive metal materials into copper crucibles. S5. Place the crucible containing the coating material, the evaporation boat, and the substrate into the coating machine in sequence; S6. Vacuuming the coating machine; S7. The vacuum degree of the coating machine reaches 8×10⁻⁶. -3After Pa, the material in the crucible is heated to a molten state. Ag and Al do not participate in this process. S8. The vacuum degree of the coating machine reaches 3×10⁻⁶. -3 After Pa, the substrate is cleaned using an ion source to improve film adhesion; S9. Input the film system and coating parameters to be deposited. This invention is a layered thin film structure. The next layer is deposited only after the first layer has been completely deposited. If Ag or Al is used as the destructive metal layer, silver on the evaporation boat is evaporated by resistance heating and then deposited onto the substrate, or Ag or Al in the molybdenum crucible is deposited by electron beam evaporation. If Cu is used as the destructive metal layer, Cu in the molybdenum crucible is deposited by electron beam evaporation. If other metals are used as the destructive metal layer, metals in the copper crucible are deposited by electron beam evaporation. If SiO2 is used as the non-destructive dielectric layer, SiO2 in the annular crucible is deposited by electron beam evaporation. If other dielectric materials are used as the non-destructive dielectric layer, dielectric materials in the copper crucible are deposited by electron beam evaporation.

[0048] In addition, oxides in the dielectric layer material, such as SiO2, Ta2O5, TiO2, and HfO2, require oxygen to be introduced during the plating process to prevent oxygen loss. S10. Begin coating; S11. After coating is completed, allow the film to cool properly, then remove the film.

[0049] Example 1 like Figure 1 , Figure 2 and Figure 3 As shown, the thin film structure consists of a substrate (Sub), a multi-element film layer, and a mirror-image multi-element film layer. The structure of the multi-element film layer is (F'R). m F'', the structure of the mirror-image multilayer film is F'' T (RF) T ) m F represents the lossless dielectric layer, R represents the lossy metal layer, and F' represents F. n The structure consists of n lossless dielectric layers, where F'' is F P It consists of p lossless dielectric layers, where n, p, and m are the number of times the layers are repeatedly stacked, and are positive integers. In this embodiment, m=1, n=3, p=2, (F'R) m F''F'' T (RF) T ) m For (F) ^3 R) ^1 F ^2 F ^2 (RF ^3 ) ^1The layer structure from the substrate upwards is MgF2 / Si / MgF2 / Cu / MgF2 / Si / Si / MgF2 / Cu / MgF2 / Si / MgF2. The two middle layers of Si material, being of the same material, can be combined into one layer, i.e., MgF2 / Si / MgF2 / Cu / MgF2 / Si / MgF2 / Cu / MgF2 / Si / MgF2, as shown in Table 1. The substrate is a K9 glass deposition film with a diameter of 80 mm, a thickness of 2 mm, and a surface quality of 20 / 10. The specific thickness of each layer is given in Table 1. Figure 4 This is a reflection spectrum of the visible light band (400nm-800nm) under vertical incidence, as shown in one embodiment. Figure 5 This is a chromaticity coordinate diagram of one embodiment at a vertical incident angle. From... Figure 4 It can be seen that the average reflectivity of this film system in the near-infrared band can reach 83.45%, which can greatly reduce the absorption of solar radiation energy, thereby achieving cooling. From Figure 5 It can be seen that the chromaticity coordinates of this film system are x=0.22, y=0.33, which is cyan and close to the standard cyan chromaticity coordinates, demonstrating its high color saturation.

[0050] Table 1. Film thickness parameters for one of the embodiments (unit: nm)

[0051] Example 2 like Figure 1 , Figure 2 and Figure 3 As shown, the thin film structure consists of a substrate (Sub), a multi-element film layer, and a mirror-image multi-element film layer. The structure of the multi-element film layer is (F'R). m F'', the structure of the mirror-image multilayer film is F'' T (RF) T ) m F represents the lossless dielectric layer, R represents the lossy metal layer, and F' represents F. n The structure consists of n lossless dielectric layers, where F'' is F P It consists of p lossless dielectric layers, where n, p, and m are the number of times the layers are repeatedly stacked, and are positive integers. In this embodiment, m=1, n=3, p=2, (F'R) m F''F'' T (RF) T ) m For (F) ^3 R) ^1 F ^2 F ^2 (RF ^3 ) ^1The layer structure from the substrate upwards is MgF2 / Si / MgF2 / Cu / Si / MgF2 / MgF2 / Si / Cu / MgF2 / Si / MgF2. The two middle layers of MgF2 material, being of the same material, can be combined into one layer. The MgF2 / Si / MgF2 / Cu / Si / MgF2 / Si / Cu / MgF2 / Si / MgF2 structure is shown in Table 2. The substrate is a K9 glass deposition film with a diameter of 80 mm, a thickness of 2 mm, and a surface quality of 20 / 10. The specific thickness of each layer is given in Table 2. Figure 6 This is the reflectance spectrum of the visible light band (400nm-800nm) under vertical incidence, as shown in Example 2. Figure 7 This is a chromaticity coordinate diagram of Example 2 at a vertical incident angle. From... Figure 6 It can be seen that the average reflectivity of this film system in the near-infrared band can reach 85.20%, which can greatly reduce the absorption of solar radiation energy, thereby achieving cooling. From Figure 7 It can be seen that the chromaticity coordinates of this film system are x=0.32, y=0.15, which is magenta and close to the chromaticity coordinates of the standard cyan, demonstrating its high color saturation.

[0052] Table 2. Film thickness parameters for Example 2 (unit: nm)

[0053] Example 3 like Figure 1 , Figure 2 , Figure 3 As shown, the thin film structure consists of a substrate (Sub), a multi-element film layer, and a mirror-image multi-element film layer. The structure of the multi-element film layer is (F'R). m F'', the structure of the mirror-image multilayer film is F'' T (RF) T ) m F represents the lossless dielectric layer, R represents the lossy metal layer, and F' represents F. n The structure consists of n lossless dielectric layers, where F'' is F P It consists of p lossless dielectric layers, where n, p, and m are the number of times the layers are repeatedly stacked, and are positive integers. In this embodiment, m=1, n=3, p=2, (F'R) m F''F'' T (RF) T ) m For (F) ^3 R) ^1 F ^2 F ^2 (RF ^3 ) ^1The layer structure from the substrate upwards is MgF2 / Si / MgF2 / Cu / MgF2 / Si / Si / MgF2 / Cu / MgF2 / Si / MgF2. The two middle layers of Si material, being of the same material, can be combined into one layer, i.e., MgF2 / Si / MgF2 / Cu / MgF2 / Si / MgF2 / Cu / MgF2 / Si / MgF2, as shown in Table 3. The substrate is a K9 glass deposition film with a diameter of 80 mm, a thickness of 2 mm, and a surface quality of 20 / 10. The specific thickness of each layer is given in Table 3. Figure 8 This is the reflectance spectrum of the visible light band (400nm-800nm) under vertical incidence, as shown in Example 3. Figure 9 This is the chromaticity coordinate diagram of Example 3 at the vertical incident angle. From... Figure 8 It can be seen that this film system is effective in the near-infrared band. The average reflectivity can reach 81.71%, which can greatly reduce the absorption of solar radiation energy, thereby achieving cooling. From Figure 9 It can be seen that the chromaticity coordinates of this film system are x=0.42, y=0.51, which is yellow and close to the chromaticity coordinates of the standard cyan, demonstrating its high color saturation.

[0054] Table 3. Thickness parameters of film layer in Example 3 (unit: nm)

[0055] Example 4 like Figure 1 , Figure 2 , Figure 3 As shown, the thin film structure consists of a substrate (Sub), a multi-element film layer, and a mirror-image multi-element film layer. The structure of the multi-element film layer is (F'R). m F'', the structure of the mirror-image multilayer film is F'' T (RF) T ) m F represents the lossless dielectric layer, R represents the lossy metal layer, and F' represents F. n The structure consists of n lossless dielectric layers, where F'' is F P It consists of p lossless dielectric layers, where n, p, and m are the number of times the layers are repeatedly stacked, and are positive integers. In this embodiment, m=1, n=3, p=2, (F'R) m F''F'' T (RF) T ) m For (F) ^3 R) ^1 F ^2 F ^2 (RF ^3 ) ^1The layer structure, from the substrate upwards, is MgF2 / Si / MgF2 / Cu / MgF2 / Si / Si / MgF2 / Cu / MgF2 / Si / MgF2. The two middle layers of Si material, being of the same material, can be combined into one layer, i.e., MgF2 / Si / MgF2 / Cu / MgF2 / Si / MgF2 / Cu / MgF2 / Si / MgF2, as shown in Table 4. This thin film structure is symmetrical. The substrate is a K9 glass deposition film with a diameter of 80 mm, a thickness of 2 mm, and a surface quality of 20 / 10. The specific thickness of each layer is given in Table 3. Figure 10 This is the reflectance spectrum of the visible light band (400nm-800nm) under vertical incidence, as shown in Example 4. Figure 11 This is the chromaticity coordinate diagram of Example 4 at the vertical incident angle. From... Figure 10 It can be seen that the average reflectivity of this film system in the near-infrared band can reach 49.4%, which can significantly reduce the absorption of solar radiation energy, thereby achieving cooling. From Figure 11 It can be seen that the chromaticity coordinates of this film system are x=0.42, y=0.51, which is yellow and close to the chromaticity coordinates of the standard cyan, demonstrating its high color saturation.

[0056] Table 4. Film thickness parameters for Example 4 (unit: nm)

[0057] The above description is only a part of the embodiments of the present invention and does not limit the scope of protection of the present invention. Any equivalent device or equivalent process transformation made based on the content of the present invention specification and drawings, or direct or indirect application in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A colored cooling optical thin film based on a composite multi-layer film structure, characterized in that, The thin film includes: A multi-element membrane layer, wherein the structure of the multi-element membrane layer is (F'R). m F'', where R is the lossy metal layer, F' is the first composite lossless dielectric layer formed by stacking multiple lossless dielectric layers from bottom to top, F'' is the second composite lossless dielectric layer formed by stacking multiple lossless dielectric layers from bottom to top, m is the number of repeated stacking, and m≥1; A mirror-image multi-element film layer disposed on the multi-element film layer, the structure of the mirror-image multi-element film layer being F'' T (RF) T ) m , where F'' T The arrangement order of the film materials is symmetrical with that of F''. T The arrangement of the film materials is symmetrical with respect to F', and the thickness of each film layer in the mirror-image multi-element film layer is not exactly the same as the thickness of the corresponding film layer in the multi-element film layer; The multi-element film layer and the mirror multi-element film layer form a symmetrical composite film system. The symmetrical composite film system constitutes a Fabry-Perot cavity structure, which is used to generate reflective structural colors in the visible light band and achieve high reflectivity in the 0.8–2.5 μm near-infrared band.

2. The colored cooling optical thin film based on a composite multi-layer film structure as described in claim 1, characterized in that, The (F'R) in the multi-component membrane layer m The structure is F1'R1F2'R2…F m 'R m Among them, F1', F2'...F m 'F' is the first composite lossless dielectric layer with the same or different structures, R1, R2...R m The damaged metal layer can be made of the same or different materials; the (RF') in the mirrored multi-element film layer T ) m The structure is R m F m ' T …R2F2' T R1F1' T .

3. The colored cooling optical thin film based on a composite multi-layer film structure as described in claim 1, characterized in that, The first composite non-destructive dielectric layer F' in the multi-element film layer is composed of n non-destructive dielectric layers F stacked from bottom to top, specifically F 11 F 12 …F 1n , of which F 11 F 12 …F 1n The non-destructive dielectric layer F can be made of different or the same material; the second composite non-destructive dielectric layer F'' in the multi-element film layer is composed of p non-destructive dielectric layers F stacked from bottom to top, specifically F 21 F 22 …F 2p , of which F 21 F 22 …F 2p F is a non-destructive dielectric layer made of different or the same material; F'' in the mirror-image multi-element film layer T The structure is F 2p …F 22 F 21 F' in the mirror-image multi-element film layer T The structure is F 1n …F 12 F 11 , where n and p are the number of times the stack is repeated, and n≥1, p≥1.

4. The colored cooling optical thin film based on a composite multi-layer film structure as described in claim 3, characterized in that, The multi-element film layer and the mirrored multi-element film layer are connected by F'' and F''. T The adjacent layers form a symmetrical composite dielectric layer structure F''F'' T When p≥2, F'' and F'' T Adjacent settings, where F'' is F 21 F 22 …F 2p , F'' T For F 2p …F 22 F 21 two adjacent F 2p The membrane materials are the same, and they are merged into one layer to form a symmetrical membrane structure F. 21 F 22 …F 2p …F 22 F 21 .

5. The colored cooling optical thin film based on a composite multi-layer film structure as described in claim 1, characterized in that, The material of the non-destructive dielectric layer F has a refractive index of 1.2-5 and an extinction coefficient of 0-1 in the wavelength range of 380nm-780nm. The material of the non-destructive dielectric layer F is selected from at least one of MgF2, LaTiO3, SiO2, Ta2O5, TiO2, HfO2, Al2O3 and Si. The thickness of the non-destructive dielectric layer F ranges from 20nm to 1000nm.

6. The colored cooling optical thin film based on a composite multi-layer film structure as described in claim 1, characterized in that, The material of the damaged metal layer R is selected from at least one of Au, Cu, Ag, Al, Ni, Cr, Ti and W, and the thickness of the damaged metal layer R ranges from 1 nm to 200 nm.

7. The colored cooling optical thin film based on a composite multi-layer film structure as described in claim 1, characterized in that, The thickness of the non-destructive dielectric layer F ranges from 20nm to 800nm, and the thickness of the destructive metal layer R ranges from 1nm to 60nm.

8. A method for preparing a colored cooling optical thin film based on a composite multi-layer film structure as described in any one of claims 1 to 7, characterized in that, Includes the following steps: Step 1: Provide a substrate and clean the substrate. Step 2: Place the cleaned substrate in the vacuum coating equipment; Step 3: Sequentially deposit each of the multi-layer films on the substrate, including the first composite non-destructive dielectric layer F', the destructive metal layer R, and the second composite non-destructive dielectric layer F'', to form (F'R). m F'' structure, where R is a lossy metal layer, F' is a first composite lossless dielectric layer formed by stacking multiple lossless dielectric layers from bottom to top, F'' is a second composite lossless dielectric layer formed by stacking multiple lossless dielectric layers from bottom to top, m is the number of repeated stacking, and m≥1; Step 4: Sequentially deposit each layer of the mirror-image multi-layer film on the multi-layer film, including F'' T and (RF' T ) m , forming F'' T (RF) T ) m Structure, where F'' T The arrangement order of the film materials is symmetrical with that of F''. T The arrangement of the film materials is symmetrical with respect to F', and the thickness of each film layer in the mirror-image multi-element film layer is not exactly the same as the thickness of the corresponding film layer in the multi-element film layer; Step 5: After deposition is complete, cool and remove the film.

9. The method for preparing a colored cooling optical thin film based on a composite multi-layer film structure as described in claim 8, characterized in that, The substrate material is selected from glass, polished stainless steel, polished mirror aluminum, polyethylene terephthalate, cellulose triacetate, polymethyl methacrylate, polycarbonate / polymethyl methacrylate composite, polyimide, polypropylene, polyvinyl chloride, polyvinyl butyral, ethylene vinyl acetate copolymer, polyurethane elastomer, polytetrafluoroethylene, fluoroethyl propylene, or polydifluoroethylene.

10. The method for preparing a colored cooling optical thin film based on a composite multi-layer film structure as described in claim 8, characterized in that, In steps 3 and 4, each layer of the multi-element film is sequentially deposited on the substrate using physical vapor deposition, chemical vapor deposition, or pearlescent thin film liquid phase coating, and each layer of the mirror-image multi-element film is sequentially deposited on the multi-element film. The physical vapor deposition method includes ion beam sputtering deposition, magnetron sputtering deposition, electron beam evaporation, atomic layer deposition, or electron beam evaporation ion-assisted deposition. If the non-destructive dielectric layer is made of oxide material, oxygen needs to be introduced during the deposition process.

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