Thermochromic air bag based on Fabry-Perot resonant cavity structure and preparation method of thermochromic air bag

Abstract

The invention relates to a thermochromic air bag based on a Fabry-Perot resonant cavity structure and a preparation method of the thermochromic air bag. The thermochromic air bag based on the Fabry-Perot resonant cavity structure is of a spherical structure with the radius ranging from 5 cm to 5 cm in the inflated state, and the range of the central angle of the spherical surface is pi / 3-pi. The thermochromic air bag based on the Fabry-Perot resonant cavity structure comprises an upper part and a lower part, wherein the upper part comprises a flexible substrate, a metal reflecting layer, a dielectric layer and a thermochromic layer which are stacked from inside to outside; the metal reflecting layer, the dielectric layer and the thermochromic layer of the upper half part are combined to form a Fabry-Perot resonant cavity structure dynamic thermal radiation regulation and control layer; and the lower half part comprises a flexible substrate and a metal reflecting layer which are laminated from inside to outside.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochromic functional devices, and in particular relates to a thermochromic airbag based on a Fabry-Perot resonant cavity structure and a preparation method thereof. Background Art

[0002] Energy is a crucial foundation for maintaining sustainable economic development and ensuring the people's material well-being. Today, energy shortages and environmental pollution are becoming increasingly severe. While developing new energy sources, people are also striving to find ways to conserve energy and reduce consumption. Buildings are one of the primary sites for human production and daily life, and they account for a significant portion of total energy consumption. Within building energy consumption, lighting and air conditioning systems, used to improve building comfort, account for over 75% of total building energy consumption. Both of these energy consumption components are related to the building envelope, making the development of energy-efficient building envelope structures a key approach to achieving building energy conservation.

[0003] Currently, the emissivity of building walls plays a crucial role in building energy conservation and thermal management. Traditional materials typically have a fixed infrared emissivity, making them difficult to dynamically adapt to ambient temperature fluctuations. This limitation leads to increased heat loss in winter and significant internal heat accumulation in summer, which in turn increases energy consumption for heating and cooling. To address this issue, a number of low-emissivity (Low-E) coatings and high-reflectivity exterior wall materials have been introduced in recent years. These technologies effectively reduce building heat loss by reducing infrared radiation exchange. However, the adjustable capabilities of these materials remain relatively limited, typically providing only passive thermal management functions and unable to dynamically adjust their emissivity performance based on changing environmental conditions. Emissivity regulation plays a key role in building thermal management. Furthermore, by regulating the emissivity of building exterior walls, energy transfer between the ground and the exterior wall can be effectively controlled. In a low emissivity state, the exterior wall reflects more thermal radiation, reducing heat transfer from the ground to the exterior wall, thereby reducing the heat load inside the building. In a high emissivity state, the exterior wall enhances the absorption and dissipation of thermal radiation from the ground, helping to accelerate heat transfer and promote temperature balance within the building. By precisely controlling the emissivity of exterior walls, not only can heat flow be optimized, but more flexible and efficient thermal management can also be achieved under varying climate conditions. Thermochromic materials with temperature-adaptive emissivity control are gaining widespread attention. These materials automatically adjust their infrared emissivity based on the ambient temperature, maintaining low radiative heat dissipation at low temperatures to reduce energy loss, while increasing radiative heat dissipation at high temperatures to enhance the natural cooling effect. By rationally controlling the emissivity properties of building surface materials, not only can the building's thermal environment be optimized, but energy consumption and carbon emissions can also be significantly reduced.

[0004] At present, the performance of building exterior walls in the infrared band is mainly determined by the thermal radiation characteristics of the material. Traditional exterior wall materials such as concrete, masonry, gypsum, etc. usually have a high infrared emissivity (about 0.85-0.95). After being exposed to solar radiation, they tend to absorb and store heat, and then release heat to the environment through thermal radiation or convection. Although this characteristic can help keep warm in cold seasons, it will aggravate heat accumulation inside the building in hot climates and increase the cooling load. In addition, the surface roughness of traditional exterior walls is large, and they often lack the ability to reflect infrared bands, making heat regulation more passive and difficult to adapt to complex climate requirements. At the same time, as a vertical component of the building, the enclosing structure not only exchanges thermal radiation with the sky, but is also affected by ground thermal radiation.

[0005] Typically, the static properties of building envelope materials lead to cooling and heating requirements in volatile climates. This unfavorable change increases the building's overall energy consumption. Currently, building exterior walls utilize both low-emissivity and high-emissivity coatings tailored to different environments. Low-emissivity coatings are suitable for locations with higher ambient temperatures, preventing radiative heat exchange between the building and the surrounding environment. High-emissivity coatings are suitable for locations with lower ambient temperatures, allowing the building to radiate heat into the environment. However, the thermal radiation properties of these coatings remain constant, and they fail to account for radiant heat from the ground. Summary of the Invention

[0006] In response to the technical problem that the static optical properties of existing building envelope materials cannot cope with environmental changes, thereby leading to increased building energy consumption, the purpose of the present invention is to provide a thermochromic airbag based on a Fabry-Perot resonant cavity structure and a preparation method thereof.

[0007] In a first aspect, the present invention provides a thermochromic airbag based on a Fabry-Perot resonant cavity structure. The thermochromic airbag based on the Fabry-Perot resonant cavity structure is a spherical structure with a radius of 5 mm to 5 cm in an inflated state, and the range of the central angle of the sphere is π / 3-π. The thermochromic airbag based on the Fabry-Perot resonant cavity structure comprises an upper and a lower part: The upper part includes a flexible substrate, a metal reflective layer, a dielectric layer, and a thermochromic layer stacked from the inside out, and the metal reflective layer, the dielectric layer, and the thermochromic layer of the upper part are combined to form a Fabry-Perot resonant cavity structure dynamic thermal radiation control layer; The lower half includes a flexible substrate and a metal reflective layer stacked from inside to outside.

[0008] Preferably, the material of the flexible substrate includes at least one of thermoplastic polyurethane elastomer, polyimide and polyethylene terephthalate, and has a thickness of 50 to 1000 μm.

[0009] Preferably, the material of the metal emission layer is a highly reflective thin film in the visible, near-infrared and mid-infrared bands, preferably at least one of silver, aluminum, gold and magnesium; and the thickness is 50-500 nm.

[0010] Preferably, the material of the dielectric layer is a thin film transparent in the visible, near-infrared and mid-infrared bands, preferably at least one of hafnium oxide, silicon oxide, barium fluoride and calcium fluoride; and the thickness is 200-1800 nm.

[0011] Preferably, the material of the thermochromic layer includes vanadium dioxide; the thickness is 10-100 nm, preferably 10-50 nm.

[0012] In a second aspect, the present invention provides a method for preparing the above-mentioned thermochromic airbag based on the Fabry-Perot resonant cavity structure, the preparation method comprising the following steps: according to the structure of the thermochromic airbag based on the Fabry-Perot resonant cavity structure, a metal reflective layer, a dielectric layer, and a thermochromic layer are sequentially prepared on the surface of a flexible substrate by using a film-forming method such as magnetron sputtering, laser pulse deposition, molecular beam epitaxy, spin coating, spraying or pulling.

[0013] Preferably, the process of preparing the metal reflective layer on the surface of the flexible substrate by magnetron sputtering includes: using metal silver, aluminum, gold or magnesium as the target, the sputtering gas is argon, the total pressure is 0.5-2.0 Pa, the distance between the target and the substrate is 10-20 cm, the initial substrate temperature is room temperature, the DC power applied to the target is 50-100 W or the power density is 0.6-3.0 W / cm 2 .

[0014] Preferably, the preparation method of the dielectric layer includes a radio frequency power supply method or a vacuum evaporation method; Preferably, the process for preparing the electrolyte layer by the radio frequency power supply method includes: using hafnium oxide, silicon oxide, barium fluoride, and calcium fluoride as targets, the sputtering gas is argon, the total pressure is 0.5-2.0 Pa, the distance between the target and the substrate is 10-20 cm, the initial substrate temperature is room temperature, and the radio frequency power applied to the target is 100-200 W or the power density is 0.6-3.0 W / cm 2 ; Preferably, the process of preparing the electrolyte layer by vacuum evaporation comprises: first evacuating the cavity to ≤10 -3 Pa, then increase the evaporation current to 50-200A and maintain it for 5-50min.

[0015] Preferably, the method for preparing the thermochromic layer by magnetron sputtering includes the following process: using vanadium dioxide as a target material, the sputtering gas is argon and oxygen, the total pressure is 0.5-2.0 Pa, the oxygen partial pressure is 0-50%, the distance between the target and the substrate is 10-20 cm, the initial substrate temperature is room temperature, the DC power applied to the target is 100-200 W or the power density is 0.6-3.0 W / cm 2 .

[0016] Preferably, the preparation method further comprises performing high-temperature annealing on the device after the device is prepared; preferably, the temperature of the high-temperature annealing is 200-500° C., and the time is 50-1200 s.

[0017] Beneficial effects (1) The present invention designs an airbag-controlled thermochromic exterior wall structure. Compared with the traditional static exterior wall structure, it can controllably adjust the flattening and expansion of the airbag, and achieves overall improvement in the control and regulation of the active and passive performance of the exterior wall by means of thermochromic film; (2) The materials involved in the present invention are highly abundant on Earth, and thus their cost is greatly reduced compared to conventional static exterior wall low-emissivity materials such as aluminum plates. In addition, the preparation process is simple, and the material preparation conditions support large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 、 2 This is a schematic diagram of an exemplary structure of the inflated state of a thermochromic airbag based on a Fabry-Perot resonant cavity structure provided by the present invention. DETAILED DESCRIPTION

[0019] The present invention is further described below through the following embodiments. It should be understood that the following embodiments are only used to illustrate the present invention, rather than to limit the present invention.

[0020] First, if Figure 1 、 2 As shown, the present invention provides a thermochromic airbag based on a Fabry-Perot resonant cavity structure. When inflated, the thermochromic airbag based on the Fabry-Perot resonant cavity structure can be a spherical structure with a radius of 5mm-5cm, and the central angle of the sphere can range from π / 3 to π. The thermochromic airbag based on the Fabry-Perot resonant cavity structure comprises an upper and lower portion. The upper portion can include a flexible substrate, a metal reflective layer, a dielectric layer, and a thermochromic layer stacked from the inside out. The metal reflective layer, dielectric layer, and thermochromic layer in the upper portion combine to form a Fabry-Perot resonant cavity structure dynamic thermal radiation control layer. The lower portion can include a flexible substrate and a metal reflective layer stacked from the inside out.

[0021] The color-changing airbag may further include an inflation port, the function of which is to inflate the film layer according to the needs of thermal management, so that it bulges to form a high-inflated upward state and a low-inflated downward state.

[0022] The thermochromic airbag based on the Fabry-Perot resonant cavity structure provided by the present invention consists of two parts: the upper part is a dynamic thermal response film based on the Fabry-Perot resonant cavity structure, which maintains a low-emission state at low temperatures and changes to a high-emission state at high temperatures; the lower part always maintains a low-emission state. Therefore, the airbag is flat when not inflated, and the whole is in a flat low-emission state, effectively blocking the heat exchange between indoor and outdoor. When the ambient temperature continues to rise, the factor of ground radiation must be considered. The airbag is inflated, and the upper part of the airbag after inflation is a high-emission film based on the Fabry-Perot resonant cavity structure, and the building heat can be dissipated to the sky through the "atmospheric window"; the lower part is a low-emission film, which effectively blocks the ground radiation heat from entering the room.

[0023] In some embodiments, the material of the flexible substrate may include at least one of thermoplastic polyurethane (TPU), polyimide (PI) and polyethylene terephthalate (PET), and the thickness may be 50 to 1000 μm.

[0024] In some embodiments, the metal reflective layer can be made of a highly reflective thin film in the visible, near-infrared, and mid-infrared bands, preferably at least one of silver, aluminum, gold, and magnesium. The thickness can be 50-500 nm. Materials with strong infrared reflectivity and ease of preparation are preferred. Sufficient thickness is essential to ensure adequate infrared reflectivity. Excessive thickness can reduce substrate adhesion and may lead to flaking during the bubbling process.

[0025] In some embodiments, the material of the dielectric layer can be a thin film transparent in the visible, near-infrared and mid-infrared bands, preferably at least one of hafnium oxide, silicon oxide, barium fluoride, and calcium fluoride; the thickness can be 200-1800 nm. Among them, the material screening principle of the dielectric layer is that it has a high transmittance in the mid-infrared band and can be produced in batches with high quality in an industrial production manner. Its thickness is obtained based on simulation calculations. In the present invention, the upper part of the bubble constructs a Fabry-Perot resonant cavity. Therefore, if the thickness is too small, the emissivity control ability is limited, and if the thickness is too large, the same problems of decreased binding force and complex preparation are faced.

[0026] In some embodiments, the material of the thermochromic layer may include vanadium dioxide; the thickness may be 10-100 nm, preferably 10-50 nm.

[0027] The present invention selects VO2, which exhibits excellent phase transition properties near room temperature, as the top material for the Fabry-Perot resonator. The emissivity of the VO2 changes from a transmissive state to an emissive state before and after the phase transition, meaning the overall emissivity of the resonator changes from low emission to high emission. Its thickness is determined based on optical simulations. Too thin results in insufficient modulation capability, while too thick results in high emissivity both before and after the phase transition, also reducing modulation capability.

[0028] Compared to static emissivity devices, the thermochromic airbags provided by the present invention offer significant advantages. They synergistically combine a thermochromic Fabry-Perot cavity with a micro-airbag, leveraging the thermochromic temperature response to achieve temperature-adaptive emissivity control. This results in a higher number of inflation and deflation cycles, lower solar absorptivity, and a greater emissivity control range. Conventional building envelope materials typically lack emissivity control. When faced with dynamically changing ambient temperatures, air conditioning systems increase cooling and heating energy consumption for indoor temperature regulation. Furthermore, the ground also exchanges thermal radiation energy with the building. This additional energy transfer weakens the heat dissipation and insulation effectiveness of the building envelope.

[0029] Compared to the negative thermal gain of traditional flat exterior walls, which cannot isolate ground thermal radiation, this invention synergistically combines a thermochromic Fabry-Perot cavity with a micro-airbag, leveraging the temperature-responsive properties of the thermochromic structure to achieve adaptive optical performance control. Furthermore, the airbag's transformation from 2D to 3D allows for directional control of emissivity, thereby actively receiving and isolating ground thermal radiation. This coordinated control of emissivity amplitude and directionality will further enable advanced building thermal management.

[0030] Furthermore, in this patent, thermochromic materials are combined with dielectrics and metal reflective layers to form a Fabry-Perot resonant cavity structure. This thermochromic device can achieve temperature-adaptive control of emissivity. Therefore, compared with traditional enclosure materials, the thermochromic device designed in this patent can controllably adjust the thickness of each layer of film, so that the optical performance of the thermochromic device can be dynamically adjusted and the overall adjustment ability is improved. In addition, the present invention uses an airbag structure to achieve flattening and tensioning of the film. Studies have shown that by controlling the emissivity of the part of the vertical enclosure of the building facing the ground, it can further promote and avoid the transfer of building heat to the ground in the form of thermal radiation. The materials involved in the present invention are highly abundant on the earth, so the cost is greatly reduced compared to conventional static exterior wall materials such as polymer mortar and concrete, and the preparation process is simple. The preparation conditions of the materials support large-scale production, and the organic-inorganic composite structure effectively avoids interface defects.

[0031] Theoretical calculations and experiments have shown that the presence of a Fabry-Perot cavity significantly enhances the device's ability to absorb thermal radiation, thus overcoming the performance limitations of a single material in the mid-infrared band. By utilizing thermochromic materials to switch the Fabry-Perot cavity on and off in different states, the emissivity can be significantly enhanced. The basic structure of a Fabry-Perot cavity consists of a highly reflective base layer, a transmissive middle layer, and a partially transmissive / partially reflective surface layer. The core of this invention lies in utilizing the cavity to enhance the composite film's modulation capability for the mid-infrared, rather than visible, wavelengths.

[0032] The thermochromic device has excellent thermal radiation control amplitude and directional transmission control. In some embodiments, the number of inflation and deflation cycles of the thermochromic airbag based on the Fabry-Perot resonant cavity structure can be 1-10 6 , the solar absorptivity can be 0.1-0.52, and the emissivity control range can be 20-80%.

[0033] The following is an exemplary method for preparing the aforementioned thermochromic airbag based on the Fabry-Perot resonant cavity structure. The method may include the following steps: sequentially forming a metal reflective layer, a dielectric layer, and a thermochromic layer on the surface of a flexible substrate using a film-forming method such as magnetron sputtering, laser pulse deposition, molecular beam epitaxy, spin coating, spray coating, or Czochralski deposition, based on the structure of the thermochromic airbag based on the Fabry-Perot resonant cavity structure.

[0034] In some embodiments, the preparation process of the flexible substrate may include the following steps: selecting high-purity raw materials and dissolving them in a suitable solvent (for example, N,N-dimethylformamide (DMF) for TPU, N-methylpyrrolidone (NMP) for PI, and a phenol-tetrachloroethane mixed solvent for PET); after dissolving the material at a certain concentration (for example, 5-20wt%), dripping the treated solution onto the center of the substrate, and controlling the film thickness and uniformity by adjusting the spin coating speed (for example, 500-5000rpm), time, and solution volume; after coating, curing the film by stepwise heating (50-200°C, 30-150min); and finally, removing the film from the substrate by slowly peeling to ensure integrity.

[0035] In some embodiments, the process of preparing a metal reflective layer on the surface of the flexible substrate by magnetron sputtering may include: using metal silver, aluminum, gold or magnesium as a target, the sputtering gas is argon, the total pressure is 0.5-2.0 Pa, the distance between the target and the substrate is 10-20 cm, the initial substrate temperature is room temperature, and the DC power applied to the target is 50-100 W or the power density is 0.6-3.0 W / cm 2 .

[0036] In some embodiments, the dielectric layer may be prepared by a radio frequency power supply method or a vacuum evaporation method.

[0037] Preferably, the process of preparing the dielectric layer by the radio frequency power supply method may include: using hafnium oxide, silicon oxide, barium fluoride or calcium fluoride as a target material, the sputtering gas is argon, the total pressure is 0.5-2.0 Pa, the distance between the target material and the substrate is 10-20 cm, the initial substrate temperature is room temperature, and the radio frequency power applied to the target material is 100-200 W or the power density is 0.6-3.0 W / cm 2 .

[0038] Preferably, the process of preparing the dielectric layer by vacuum evaporation may include: first evacuating the cavity to ≤10 -3 Pa, then slowly increase the evaporation current to 50-200 A and maintain it for 5-50 min. This method has the advantage of being able to prepare large-scale batches.

[0039] In some embodiments, the method for preparing a thermochromic layer by magnetron sputtering may include the following process: using vanadium dioxide as a target material, the sputtering gas is argon and oxygen, the total pressure is 0.5-2.0 Pa, the oxygen partial pressure is 0-50%, the distance between the target and the substrate is 10-20 cm, the initial substrate temperature is room temperature, and the DC power applied to the target is 100-200 W or the power density is 0.6-3.0 W / cm 2 .

[0040] In some embodiments, the preparation method may further include performing high-temperature annealing on the device after preparation to further enhance the crystallinity of the device; preferably, the temperature of the high-temperature annealing may be 200-500° C., and the time may be 50-1200 s.

[0041] To be more specific, the DC magnetron sputtering system equipment used in the magnetron sputtering deposition of the present invention may include a deposition chamber, a sampling chamber, several target heads, a substrate plate, a DC current and a series of mechanical pumps and vacuum pumps, wherein the target head and the substrate plate are at a certain angle and a certain distance apart, and the DC power supply is connected to the target head. The substrate is ultrasonically cleaned, and the substrate is ultrasonically cleaned with acetone, anhydrous ethanol, and deionized water for 20 minutes each, and blown dry with compressed air. Cover a certain part of the conductive substrate with high-temperature tape as an electrode, and fix it on the substrate tray, put it into the sampling chamber, turn on the mechanical pump to pump it below 5Pa, and then open the baffle valve to send it into the vacuum degree (background vacuum degree) that has reached 10 -4 Pa and below in the sputtering room.

[0042] The specific sputtering deposition process can be as follows: high-purity argon and oxygen are introduced into the sputtering chamber, with the purity of the argon and oxygen used being 99.99% or higher. The total pressure and oxygen partial pressure in the chamber are controlled within the ranges of 0.5-2.0 Pa and 0-50%, respectively, with the oxygen partial pressure preferably being 0-25%. The vertical distance between the target and the substrate is controlled to be 10-20 cm, and the initial substrate temperature is room temperature. A DC power supply is turned on, with the power of the DC power supply controlled to be 30-200 W. The pre-sputtering time is 5-30 minutes, the sputtering time is 10-60 minutes, and the substrate temperature is room temperature. After the sputtering is completed, the substrate is removed after the substrate temperature cools to room temperature.

[0043] The following examples are further given to illustrate the present invention in detail. It should be understood that the following examples are only used to further illustrate the present invention and cannot be interpreted as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention all fall within the scope of protection of the present invention. The specific process parameters and the like in the following examples are only examples within a suitable range, and those skilled in the art can make selections within a suitable range through the description herein, and are not limited to the specific numerical values ​​exemplified below. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

[0044] Example 1

[0045] The method for preparing a thermochromic airbag based on a Fabry-Perot resonant cavity structure provided in this embodiment includes the following steps: (1) Select high-purity raw materials and dissolve N,N-dimethylformamide at a concentration of 10 wt%, then drop the treated solution onto the center of the substrate. After adjusting the spin coating speed to 2500 rpm, the spin coating is completed and then cured by stepwise heating at 100 °C for 60 min. Finally, the 500 μm TPU film is removed from the substrate by slowly peeling to ensure integrity. (2) depositing a 300 nm thick metal reflective layer film on the entire airbag by magnetron sputtering, using metallic silver as a target, argon as the sputtering gas, a total pressure of 1.0 Pa, a distance between the target and the substrate of 15 cm, an initial substrate temperature of room temperature, and a DC power supply of 75 W applied to the target; (3) In the upper part of the airbag, use barium fluoride nanopowder as raw material (3g) and vacuum evaporation to first evacuate the cavity to 10 -4 Pa, then slowly increase the evaporation current to 135 A and maintain it for 30 min to obtain a dielectric film with a thickness of 1200 nm; (4) Continue to use vanadium dioxide as a target on the surface of the dielectric part, the sputtering gas is argon and oxygen, the total pressure is 1.0 Pa, the oxygen partial pressure is 25%, the distance between the target and the substrate is 15 cm, the initial substrate temperature is room temperature, and the DC power applied to the target is 100 W to deposit a 25 nm vanadium dioxide film, and anneal at 450 ° C for 10 minutes, finally obtaining the thermochromic airbag based on the Fabry-Perot resonant cavity structure.

[0046] Example 2

[0047] The preparation method of the thermochromic airbag based on the Fabry-Perot resonant cavity structure provided in this embodiment refers to that in Example 1, with the following main differences: In step (1), the flexible substrate is a PI film.

[0048] Example 3

[0049] The preparation method of the thermochromic airbag based on the Fabry-Perot resonant cavity structure provided in this embodiment refers to that in Example 1, with the following main differences: In step (3), the evaporation current is maintained for 20 minutes to obtain a dielectric film with a thickness of 200 nm.

[0050] Example 4

[0051] The preparation method of the thermochromic airbag based on the Fabry-Perot resonant cavity structure provided in this embodiment refers to that in Example 1, with the following main differences: In step (1), the thickness of the TPU film is 50 μm.

[0052] Example 5

[0053] The preparation method of the thermochromic airbag based on the Fabry-Perot resonant cavity structure provided in this embodiment refers to that in Example 1, with the following main differences: In step (2), the thickness of the metal reflective layer is 50 nm.

[0054] Example 6

[0055] The preparation method of the thermochromic airbag based on the Fabry-Perot resonant cavity structure provided in this embodiment refers to that in Example 1, with the following main differences: In step (4), the annealing temperature is 500°C.

[0056] Example 7

[0057] The preparation method of the thermochromic airbag based on the Fabry-Perot resonant cavity structure provided in this embodiment refers to that in Example 1, with the following main differences: In step (4), the thickness of the vanadium dioxide film is 10 nm.

[0058] Example 8

[0059] The preparation method of the thermochromic airbag based on the Fabry-Perot resonant cavity structure provided in this embodiment refers to that in Example 1, with the following main differences: In step (1), the dielectric material is silicon oxide.

[0060] Example 9

[0061] The preparation method of the thermochromic airbag based on the Fabry-Perot resonant cavity structure provided in this embodiment refers to that in Example 1, with the following main differences: In step (4), the annealing temperature is 300°C.

[0062] Example 10

[0063] The preparation method of the thermochromic airbag based on the Fabry-Perot resonant cavity structure provided in this embodiment refers to that in Example 1, with the following main differences: In step (2), the material of the metal reflective layer is magnesium.

[0064] Example 11

[0065] The preparation method of the thermochromic airbag based on the Fabry-Perot resonant cavity structure provided in this embodiment refers to that in Example 1, with the following main differences: In step (3), the dielectric layer material is hafnium oxide.

[0066] Example 12

[0067] The preparation method of the thermochromic airbag based on the Fabry-Perot resonant cavity structure provided in this embodiment refers to that in Example 1, with the following main differences: In step (4), the thickness of the vanadium dioxide film is 100 nm.

[0068] Example 13

[0069] The preparation method of the thermochromic airbag based on the Fabry-Perot resonant cavity structure provided in this embodiment refers to that in Example 1, with the following main differences: In step (2), the thickness of the metal reflective layer is 500 nm.

[0070] Example 14

[0071] The preparation method of the thermochromic airbag based on the Fabry-Perot resonant cavity structure provided in this embodiment refers to that in Example 1, with the following main differences: In step (3), the thickness of the dielectric film is 1800 nm.

[0072] Example 15

[0073] The preparation method of the thermochromic airbag based on the Fabry-Perot resonant cavity structure provided in this embodiment refers to that in Example 1, with the following main differences: In step (1), the thickness of the TPU film is 1000 μm.

[0074] Comparative Example 1

[0075] The preparation method of the thermochromic airbag based on the Fabry-Perot resonant cavity structure provided in this comparative example is similar to that in Example 1, with the following main differences: In step (3), the thickness of the dielectric film is 5000 nm.

[0076] After testing, the solar absorptivity of the obtained thermochromic airbag was 0.36, and the emissivity control range was 15%.

[0077] Comparative Example 2

[0078] The preparation method of the thermochromic airbag based on the Fabry-Perot resonant cavity structure provided in this comparative example is similar to that in Example 1, with the following main differences: In step (3), the thickness of the dielectric film is 10 nm.

[0079] After testing, the solar absorptivity of the obtained thermochromic airbag was 0.16, and the emissivity control range was 11%.

[0080] Comparative Example 3

[0081] The preparation method of the thermochromic airbag based on the Fabry-Perot resonant cavity structure provided in this comparative example is similar to that in Example 1, with the following main differences: In step (2), the thickness of the metal reflective layer is 20 nm.

[0082] After testing, the solar absorptivity of the obtained thermochromic airbag was 0.39, and the emissivity control range was 14%.

[0083] The characteristic of this patent is the design of the upper hemisphere and lower hemisphere structure, which can effectively reflect the radiation from the ground to the building and radiate the heat inside the building.

[0084] Table 1 below shows the relevant parameters of the electrochromic devices prepared in Examples 1-15:

[0085] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A thermochromic airbag based on a Fabry-Perot resonant cavity structure, characterized in that: The thermochromic airbag based on the Fabry-Perot resonant cavity structure is a spherical structure with a radius of 5mm-5cm in the inflated state, and the range of the central angle of the spherical surface is π / 3-π; the thermochromic airbag based on the Fabry-Perot resonant cavity structure includes two parts, the upper and lower parts. composition: The upper part includes a flexible substrate, a metal reflective layer, a dielectric layer, and a thermochromic layer stacked from the inside out, and the metal reflective layer, the dielectric layer, and the thermochromic layer of the upper part are combined to form a Fabry-Perot resonant cavity structure dynamic thermal radiation control layer; The lower half includes a flexible substrate and a metal reflective layer stacked from inside to outside.

2. The thermochromic airbag based on the Fabry-Perot resonant cavity structure according to claim 1, characterized in that: The material of the flexible substrate includes at least one of thermoplastic polyurethane elastomer, polyimide and polyethylene terephthalate, and has a thickness of 50 to 1000 μm.

3. The thermochromic airbag based on the Fabry-Perot resonant cavity structure according to claim 1 or 2, characterized in that: The material of the metal emission layer is a highly reflective thin film in the visible, near-infrared and mid-infrared bands, preferably at least one of silver, aluminum, gold and magnesium; and the thickness is 50-500 nm.

4. The thermochromic airbag based on the Fabry-Perot resonant cavity structure according to any one of claims 1 to 3, characterized in that: The material of the dielectric layer is a thin film transparent in the visible, near-infrared and mid-infrared bands, preferably at least one of hafnium oxide, silicon oxide, barium fluoride and calcium fluoride; and the thickness is 200-1800 nm.

5. The thermochromic airbag based on the Fabry-Perot resonant cavity structure according to any one of claims 1 to 4, characterized in that: The material of the thermochromic layer includes vanadium dioxide; the thickness is 10-100 nm, preferably 10-50 nm.

6. A method for preparing a thermochromic airbag based on a Fabry-Perot resonant cavity structure according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: a metal reflective layer, a dielectric layer, and a thermochromic layer are sequentially prepared on the surface of a flexible substrate by using a film-forming method such as magnetron sputtering, laser pulse deposition, molecular beam epitaxy, spin coating, spraying, or pulling according to the structure of the thermochromic airbag based on the Fabry-Perot resonant cavity structure.

7. The preparation method according to claim 6, characterized in that The process of preparing a metal reflective layer on the surface of the flexible substrate by magnetron sputtering includes: using metal silver, aluminum, gold or magnesium as a target, using argon as the sputtering gas, having a total pressure of 0.5-2.0 Pa, a distance between the target and the substrate of 10-20 cm, an initial substrate temperature of room temperature, and applying a DC power supply of 50-100 W or a power density of 0.6-3.0 W / cm2 to the target. 2 .

8. The preparation method according to claim 6 or 7, characterized in that The preparation method of the dielectric layer includes a radio frequency power supply method or a vacuum evaporation method; Preferably, the process for preparing the electrolyte layer by the radio frequency power supply method includes: using hafnium oxide, silicon oxide, barium fluoride, and calcium fluoride as targets, the sputtering gas is argon, the total pressure is 0.5-2.0 Pa, the distance between the target and the substrate is 10-20 cm, the initial substrate temperature is room temperature, and the radio frequency power applied to the target is 100-200 W or the power density is 0.6-3.0 W / cm 2 ; Preferably, the process of preparing the electrolyte layer by vacuum evaporation comprises: first evacuating the cavity to ≤10 -3 Pa, then increase the evaporation current to 50-200A and maintain it for 5-50min.

9. The preparation method according to any one of claims 6 to 8, characterized in that The method for preparing a thermochromic layer by magnetron sputtering includes the following process: using vanadium dioxide as a target material, sputtering gas is argon and oxygen, the total pressure is 0.5-2.0 Pa, the oxygen partial pressure is 0-50%, the distance between the target material and the substrate is 10-20 cm, the initial substrate temperature is room temperature, and the DC power applied to the target material is 100-200 W or the power density is 0.6-3.0 W / cm 2 .

10. The preparation method according to any one of claims 6 to 9, characterized in that: The preparation method further comprises performing high-temperature annealing on the device after the device is prepared; preferably, the temperature of the high-temperature annealing is 200-500° C. and the time is 50-1200 seconds.

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