Composite material and preparation thereof

Abstract

A composite material comprising: a first layer of a thermochromic perovskite; a second layer of an antireflective material comprising an organic or inorganic polymer deposited on the first layer; and a third layer of a hydrophobic material deposited on the second layer. A method for preparing the composite material is also presented.

Description

Technical Field

[0001] The present invention relates to a composite material, for example, particularly, but not exclusively, a thermochromic composite material comprising a thermochromic perovskite and a material layer arranged to protect the thermochromic perovskite from excessive water contact; and a method for preparing the composite material. Background Technology

[0002] As a result of rapid urbanization, modern buildings account for over 40% of global energy consumption, leading to over 30% of urban greenhouse gas emissions. With increasingly stringent aesthetic requirements for buildings, extremely high window-to-wall ratios have become a characteristic of modern architecture. However, the high transmittance and high U-value of glass, which cannot be altered under strong sunlight, make windows a major source of heat loss / gain in all building envelopes. Therefore, energy-efficient smart windows with dynamically adjustable solar transmittance have recently attracted increasing attention to balance the goal of lower energy consumption with the aesthetic demand for more glass windows.

[0003] Thermochromic smart windows are among the most extensively researched smart window technologies. They typically utilize the thermochromic properties of metal halide perovskites to manage a building's energy use and temperature. The color transition of thermochromic perovskites (T-perovskites) generally depends on the dissociation of H₂O from the T-perovskite layer and its recombination back into the T-perovskite layer, such as through the following chemical reactions:

[0004]

[0005] Where MA is CH3NH3 + Furthermore, X is a halide anion. This means that, on the one hand, water is essential for inducing the thermochromic effect of T-perovskite. On the other hand, water can degrade / corrode T-perovskite, especially when it is continuously exposed to high humidity or water droplets. In particular, excessive water can lead to excessive haze and blurred vision through T-perovskite windows, as the presence of excess MAX will affect the crystallization process during color transition. Additionally, excessive water can also act as a solvent to dissolve the lead content in T-perovskite during the thermochromic process, leading to lead leakage and threatening the environment and public health.

[0006] While there are reports of methods to circumvent the aforementioned problems, these approaches often introduce another issue or necessitate sacrificing the optical and color-conversion properties of T-perovskites. For example, a common method for protecting T-perovskites is to seal them within double-glazed windows. However, this method requires airtight packaging, making window assembly difficult and posing a risk of leakage over long-term use. Alternatively, T-perovskites can be protected by covering them with a protective layer; however, this method may result in insufficient water vapor supply to the T-perovskites for color conversion. Another approach involves reducing the size of the T-perovskites to 2D. However, 2D T-perovskites typically suffer from high T-transformation properties. c (>60℃) and a long transition time (t>6 hours), which is related to its T c 3D counterparts with values ​​close to room temperature and t values ​​of only a few minutes are essentially incomparable. Therefore, developing durable and waterproof T-perovskite windows with excellent optical and transformation properties remains a challenge.

[0007] The present invention seeks to eliminate or at least mitigate this disadvantage by providing a new or otherwise improved composite material (in particular, a composite material comprising a thermochromic perovskite and a material layer arranged to protect the thermochromic perovskite from excessive water contact in window applications). Summary of the Invention

[0008] In a first aspect of the invention, a composite material is provided comprising: a first layer of thermochromic perovskite; a second layer of an antireflective material comprising an organic or inorganic polymer deposited on the first layer; and a third layer of a hydrophobic material deposited on the second layer.

[0009] In an optional embodiment, the first layer comprises a substrate made of glass or PET, on which a thermochromic perovskite layer is deposited. Optionally, the thermochromic perovskite comprises a halide-based perovskite compound having the general formula A4BX6·2H2O, wherein A is a monovalent organic cation, B is a divalent cation, and X is one or more halides. Optionally, A4BX6·2H2O reversibly changes to ABX3 in response to a temperature change. Optionally, A is selected from CH3NH3. + and CH(NH2)2 + Any of the following; B is selected from Pb 2+ Sn 2+ 、Ge 2+ Mg 2+ and Ca 2+ Either of the following; and X is selected from I. - ,Br - Cl - And any combination thereof.

[0010] In an optional embodiment, the halide-based perovskite compound has the general formula (CH3NH3)4PbI. 6-x- y Br x Cl y ·2H2O, where x and y are each 0 or positive integers, and x+y≤6.

[0011] In one embodiment of the invention, the halide-based perovskite compound is (CH3NH3)4PbI. 6- y Cl y • 2H₂O, where y is 0 to 6. Optionally, the thickness of the thermochromic perovskite layer is 1.6 μm.

[0012] Optionally, the antireflective material has a refractive index between that of air and thermochromic perovskite. Optionally, the antireflective material comprises any of the following: epoxy resin, poly(methyl methacrylate), polyvinylpyrrolidone, poly(vinyl alcohol), polydimethylsiloxane, poly(acrylic acid), poly(acrylamide), poly(aniline), poly(ethylene oxide), poly(N-acryloyloxysuccinimide), poly(N-isopropylacrylamide), poly(N-isopropylmethacrylamide), poly(N-vinylcaprolactam), poly(N-vinylpyrrolidone), poly(methacrylic acid), poly(styrene sulfonic acid), polyurethane, poly(propylene oxide), perhydropolysilazane, or combinations thereof.

[0013] In one embodiment of the invention, the antireflective material is a perhydropolysilazane. Optionally, the perhydropolysilazane contains SiO₂. x / SiON x It takes the form of a homogeneous inorganic membrane.

[0014] Optionally, the hydrophobic material comprises a superhydrophobic layer. In one embodiment of the invention, the superhydrophobic layer comprises a fluorinated nanocoating layer. Optionally, the fluorinated nanocoating layer is any one of fluorinated SiO2, fluorinated TiO2, and fluorinated ZnO.

[0015] In a second aspect of the invention, a method for preparing a composite material according to the first aspect is provided, the method comprising the steps of: coating a thermochromic perovskite onto a substrate made of glass or PET to form a first layer; coating an antireflective material onto the first layer to form a second layer; and coating silica-based nanoparticles onto the second layer to form a third layer.

[0016] Optionally, the thermochromic perovskite is annealed after it is coated onto the substrate to form the first layer.

[0017] In one embodiment of the present invention, the thermochromic perovskite is (CH3NH3)4PbI. 6-y Cl y A halide-based perovskite precursor, ·2H2O, wherein y is 0 to 6, is prepared by mixing CH3NH3I and PbCl2 in a molar ratio of about 6.5:1. Optionally, it is annealed at about 100°C for about 1 hour.

[0018] Optionally, the antireflective material comprises a homogeneous inorganic material that is cured by spin-coating or scraping onto the first layer.

[0019] In one embodiment of the invention, the homogeneous inorganic material is prepared from perhydropolysilazane dissolved in dibutyl ether.

[0020] Optionally, the first, second, and third layers are formed by a solution-based coating method. In an optional embodiment, the first and second layers are formed by spin coating. In another optional embodiment, the third layer is formed by ultrasonic spraying.

[0021] In one embodiment of the present invention, the silica-based nanoparticles are SiO2 nanoparticles, such as fluorinated SiO2 nanoparticles, which are deposited on the second layer by simultaneously coating a solution of SiO2 nanoparticles with an ultrasonic spraying method and atomizing the solvent in the solution. Attached Figure Description

[0022] The invention will now be described more specifically by way of example only with reference to the accompanying drawings, in which:

[0023] Figure 1 This is a schematic diagram illustrating a composite material according to one embodiment of the present invention;

[0024] Figure 2 Transmittance spectra from FDTD simulations and experiments are shown to validate the FDTD model. This figure also demonstrates that, in both simulation and experimental results, the transmittance of the PHPS-coated T-perovskite window (PTPW) is higher than that of the original T-perovskite window (TPW).

[0025] Figure 3 This is a schematic diagram illustrating the manufacturing process of the thermochromic perovskite smart window (MTPW), inspired by face masks.

[0026] Figure 4A This is a cross-sectional SEM image of T-perovskite coated on glass;

[0027] Figure 4B This is a cross-sectional SEM image of PHPS coated on T-perovskite;

[0028] Figure 5 EDS analysis of the PHPS membrane is shown;

[0029] Figure 6 The FTIR spectrum of PHPS during the curing process is shown;

[0030] Figure 7 The images shown are of MTPW in its cold and hot states;

[0031] Figure 8 H-MAIPbI was shown 3-x Cl x (MA4PbI of the present invention) 6-x Cl x ·2H2O or (CH3NH3)4PbI 6-y Cl y Complex refractive index of 2H₂O in cold and hot states;

[0032] Figure 9 This is a schematic diagram illustrating light transmission through a rough surface;

[0033] Figure 10A This is a schematic diagram illustrating vacuum-assisted deposition of coatings;

[0034] Figure 10B The image shows a SEM image (left) of SiO2 sputtered onto T-perovsk and a photograph (right) of T-perovsk after magnetron sputtering.

[0035] Figure 11 The transmittance spectra of glass and PHPS-coated glass are shown, demonstrating the high transparency of the PHPS coating. The PHPS coating has a thickness of approximately 1.8 μm.

[0036] Figure 12 This is a schematic diagram illustrating solution-based coating;

[0037] Figure 13 The contact angle of PHPS coated on glass is shown;

[0038] Figure 14 The transmittance spectra of TPW and MTPW, as well as the solar spectrum of AM1.5G, are shown.

[0039] Figure 15 This is a schematic diagram illustrating specular transmitted light and diffuse transmitted light;

[0040] Figure 16 Photos of TPW and MTPW are shown, and their light haze is compared;

[0041] Figure 17The light haze of TPW, PTPW and MTPW in the wavelength range of 300-800nm ​​is shown;

[0042] Figure 18 SEM images, 3D optical surface profiles, and roughness of the original TPW, PTPW, and MTPW are shown.

[0043] Figure 19 This is a schematic diagram illustrating the propagation of light through a rough surface;

[0044] Figure 20 This is a schematic diagram illustrating the FDTD model used to simulate light transmission, reflection, and propagation direction;

[0045] Figure 21 The light propagation process at the air / window interface of an ideal smooth TPW, a rough TPW, and a PTPW is shown;

[0046] Figure 22 The stimulated reflectivity of TPW and PTPW is shown;

[0047] Figure 23 The angular distribution of scattered light in the transmission and reflection fields of the TPW is shown;

[0048] Figure 24 The angular distribution of scattered light in the transmission and reflection fields of a PTPW is shown.

[0049] Figure 25 An FDTD simulation model for calculating the scattering efficiency of SiO2 nanoparticles is shown.

[0050] Figure 26 The scattering efficiency of SiO2 nanoparticles of different sizes is shown.

[0051] Figure 27 This is a TEM image of the SiO2 nanoparticles on the top layer of MTPW.

[0052] Figure 28 A comparison of the transmittance spectra of PTPW and MTPW is shown to verify that SiO2 nanoparticles do not impair transparency.

[0053] Figure 29 The relationship between the transmittance of MTPW and TPW at 550 nm and temperature is shown, illustrating the transition process with temperature changes.

[0054] Figure 30 The transition times for MTPW and the original TPW are shown;

[0055] Figure 31A Images of time-dependent contact angle measurements for TPW, PTPW, and MTPW are shown.

[0056] Figure 31B This is a graph of the contact angle versus time, showing the superhydrophobic, hydrophobic, and hydrophilic regions, and the corresponding... Figure 31A Time-dependent contact angle measurements of TPW, PTPW, and MTPW.

[0057] Figure 32 This is an image showing the surface of the original TPW being rapidly damaged by water droplets dripping onto it;

[0058] Figure 33 The SEM top view of the surface morphology obtained by spraying SiO2 nanoparticles for different cycles and their corresponding contact angles are shown.

[0059] Figure 34 The relationship between the water contact angle of MTPW and the spraying cycle of SiO2 nanoparticles during the manufacturing process is shown.

[0060] Figure 35 The superhydrophobicity of MTPW was demonstrated. Water droplets bounced off the MTPW in both cold and hot conditions.

[0061] Figure 36A The optical performance (τ) of the original TPW in ambient conditions (23°C and 60% RH) is shown. lum,热 τ lum,冷 and Δτ sol );

[0062] Figure 36B The optical performance (τ) of the original MTPW in ambient conditions (23°C and 60% RH) is shown. lum,热 τ lum,冷 and Δτ sol );

[0063] Figure 37A The optical performance (τ) of the original TPW in a humid and hot environment (35°C and 80% RH) is shown. lum,热 τ lum,冷 and Δτ sol );

[0064] Figure 37B The optical performance (τ) of the original MTPW in a humid and hot environment (35°C and 80% RH) is shown. lum,热 τ lum,冷 and Δτ sol );

[0065] Figure 38A The Δτ values ​​of TPW and MTPW in the surrounding environment are shown. sol The decay rate;

[0066] Figure 38BThe Δτ values ​​of TPW and MTPW in a humid and hot environment are shown. sol The decay rate;

[0067] Figure 39A The immersion of the original TPW and MTPW in water is shown;

[0068] Figure 39B The XRD pattern of the pristine T-perovskite film immersed in water is shown. The observed major peaks are consistent with those of PbI2.

[0069] Figure 39C It shows the corresponding Figure 39A The Pb concentration of the original TPW and MTPW in the soaking water;

[0070] Figure 40A The images show the flexible MTPW film in cold and hot states;

[0071] Figure 40B These are photos of commercial energy-saving window films;

[0072] Figure 40C The transmittance spectra of commercial window films and MTPW films are shown;

[0073] Figure 41 This is a diagram illustrating the locations of New York, Philadelphia, Washington, Atlanta, and Orlando, as well as the building models used in the EnergyPlus simulation;

[0074] Figure 42 It is a table summarizing information about the buildings used in the EnergyPlus simulation;

[0075] Figure 43 This is a schematic diagram illustrating the window structure (ordinary window, commercial window film pasted on the window, and MTPW window film pasted on the window) in the EnergyPlus simulation;

[0076] Figure 44 This is a table summarizing the optical information of the windows used in the EnergyPlus simulation;

[0077] Figure 45 This is a table summarizing climate information for US cities used in EnergyPlus simulations;

[0078] Figure 46 The energy savings achieved over one year by using MTPW and commercial window film compared to normal windows are shown.

[0079] Figure 47 The diagram illustrates building energy consumption in New York City using standard windows, MTPW film, and commercial window film.

[0080] Figure 48 The data shows Philadelphia's monthly energy consumption and savings.

[0081] Figure 49 The energy consumption of conventional windows, MTPW film, and commercial window film in Philadelphia is shown.

[0082] Figure 50 The energy consumption of using conventional windows, MTPW film, and commercial window film in Orlando is shown; and

[0083] Figure 51 The data shows Orlando's monthly energy consumption and savings. Detailed Implementation

[0084] As used herein, unless the context clearly indicates otherwise, the forms “a / kind” and “the / said” are intended to include both singular and plural forms.

[0085] The terms “example” or “exemplary” as used in this invention are intended to serve as examples, instances, or illustrations. Any aspect or design described as “exemplary” in this disclosure is not necessarily to be construed as being more preferred or advantageous than other aspects or designs. Rather, the use of the terms “example” or “exemplary” is intended to present concepts in a specific manner. As used in this application, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless otherwise specified or clear from the context, “X adopts A or B” is intended to mean any natural inclusive permutation of natural inclusive permutations. That is, “X adopts A or B” is satisfied in any of the foregoing examples if X adopts A; X adopts B; or X adopts both A and B.

[0086] Without intending to be limited by theory, the inventors have designed a composite material, particularly a thermochromic composite material, through their own research, experimentation, and testing. This composite material exhibits significant haze reduction, enhanced durability / lifespan under ambient humidity conditions (e.g., at an ambient temperature with approximately 60% humidity), and reduced lead leakage. The thermochromic composite material is designed by employing a material layer comprising antireflective and hydrophobic materials on a thermochromic perovskite surface. This reduces light scattering on the surface of the thermochromic perovskite and / or decreases the rate of water vapor / moisture transport to the thermochromic perovskite, thereby providing enhanced specular transmittance and durability against water / humidity-related degradation.

[0087] refer to Figure 1Exemplary embodiments of the composite material according to the present invention are provided. As shown, a composite material 100 is provided, in particular, a thermochromic composite material 100 comprising: a first layer 102 of thermochromic perovskite; a second layer 104 of an antireflective material comprising an organic or inorganic polymer deposited on the first layer; and a third layer 106 of a hydrophobic material deposited on the second layer.

[0088] The first layer may include a substrate 108 on which a thermochromic perovskite layer may be deposited. The material of the substrate may be selected according to actual needs. For example, in one embodiment, the substrate 108 may be a rigid substrate, such as a glass substrate. In another embodiment, the substrate 108 may be a flexible substrate, such as a polyimide or polyethylene terephthalate (PET) substrate.

[0089] Thermochromic perovskites can comprise halide-based perovskite compounds having the general formula A4BX6·2H2O, where A is a monovalent organic cation, B is a divalent cation, and X is one or more halides. The term "thermochromic perovskite" generally refers to a perovskite arranged to undergo chemical and / or phase transitions / transformations in response to external temperature changes (particularly to the extent that the temperature exceeds or falls below the critical transition temperature of the perovskite). Specifically, such chemical and / or phase transitions / transformations will be accompanied at least by changes in, for example, luminescent transmittance, color, etc. For example, in this embodiment, the halide-based perovskite compound A4BX6·2H2O can reversibly change to ABX3 in response to temperature changes, such as through a hydration-dehydration process. This change in chemical composition can cause the thermochromic perovskite to change from a transparent state to a colored state.

[0090] In one embodiment, the halide-based perovskite compound having the general formula A4BX6·2H2O can be wherein A is selected from CH3NH3. + (MA) and CH(NH2)2 + Any of (FA); B is selected from Pb 2+ Sn 2+ 、Ge 2+ Mg 2+ and Ca 2+ Either of the following; and X is selected from I. - ,Br - Cl - And any combination thereof. In one example embodiment, the halide-based perovskite compound may have the general formula (CH3NH3)4PbI 6-x-y Br x Cl y·2H₂O, where x and y are each 0 or positive integers, and x + y ≤ 6. That is, x and y can each be from 0 to 6, where x + y ≤ 6. In a specific implementation, the halide-based perovskite compound can be (CH₃NH₃)₄PbI 6-y Cl y ·2H2O, where y is 0 to 6.

[0091] It should be understood that the thickness of the thermochromic perovskite layer can affect the optical properties of the composite material, such as luminous transmittance. In one embodiment, the thermochromic perovskite layer may have a thickness of about 1.4 μm to about 1.8 μm, about 1.4 μm to about 1.7 μm, about 1.5 μm to about 1.7 μm, about 1.6 μm to about 1.8 μm, or about 1.6 μm to about 1.7 μm. Preferably, the thermochromic perovskite layer may have a thickness of about 1.6 μm.

[0092] As described above, the second layer 104 of the antireflective material may comprise an organic or inorganic polymer deposited on the first layer 102. As used herein, the term "antireflective material" generally describes a material, particularly a polymer, more particularly an organic and / or inorganic polymer, arranged to reduce reflection and / or light scattering from the surface of the thermochromic perovskite layer. Specifically, the antireflective material may be arranged to reduce reflection, for example, by providing a substantially smooth surface on the thermochromic perovskite layer and / or having a refractive index (n) matching the air-thermochromic perovskite layer interface. In one example embodiment, the antireflective material may have an R0 of approximately 55 nm. a The phrase "matching" generally indicates that the refractive index of the antireflective material can be close to or between that of air (n≈1) and thermochromic perovskite (n≈2). In one example embodiment, the antireflective material may have a refractive index between that of air and thermochromic perovskite, which thus improves the light propagation path's tolerance to surface roughness, thereby reducing light scattering at the boundaries of the thermochromic perovskite surface. Preferably, the refractive index of the antireflective material can be from about 1.5 to about 1.55.

[0093] Antireflective materials may include any of the following: epoxy resin, poly(methyl methacrylate), polyvinylpyrrolidone, poly(vinyl alcohol), polydimethylsiloxane, poly(acrylic acid), poly(acrylamide), poly(aniline), poly(ethylene oxide), poly(N-acryloyloxysuccinimide), poly(N-isopropylacrylamide), poly(N-isopropylmethylacrylamide), poly(N-vinylcaprolactam), poly(N-vinylpyrrolidone), poly(methacrylic acid), poly(styrene sulfonic acid), polyurethane, poly(propylene oxide), perhydropolysilazane, or combinations thereof.

[0094] In one embodiment, the antireflective material may be perhydropolysilazane (PHPS). The terms "perhydropolysilazane," "polyperhydropolysilazane," or "inorganic polysilazane" generally refer to a polymer in which silicon and nitrogen atoms alternately form the basic backbone. Specifically, perhydropolysilazane may contain SiO₂. x / SiON x It takes the form of a homogeneous inorganic film. SiO x / SiON x The film can have a refractive index substantially similar to that of ordinary SiO2 (n≈1.5). Furthermore, it is believed that SiO2 formed from PHPS... x / SiON x The film will be superior to ordinary SiO2 because the deposition of ordinary SiO2 films typically relies on high-vacuum cleanroom coating methods, such as chemical vapor deposition (CVD) and physical vapor deposition (PEVD). These methods require expensive deposition equipment and can only deposit conformal layers on rough surfaces, which is not considered helpful for smooth surfaces, especially thermochromic perovskite surfaces with multiple valleys. In contrast, PHPS can be deposited via solution-based coating processes such as spin coating and spray coating, which is considered effective in reducing the roughness of thermochromic perovskite surfaces. A detailed comparison will be disclosed in a later part of this disclosure.

[0095] The third layer 106 of the hydrophobic material may comprise a superhydrophobic layer. As used herein, the phrase "superhydrophobic" refers to a material or surface of a material having a water droplet contact angle of about 150° or greater, such as about 150° to about 200°, about 150° to about 190°, about 155° to about 190°, about 155° to about 180°, about 155° to about 170°, or about 155° to about 165°. In one embodiment, the superhydrophobic layer may have a water contact angle of about 160°. Preferably, the superhydrophobic layer may comprise a layer of fluorinated nanocoating, such as any one of fluorinated SiO2, fluorinated TiO2, and fluorinated ZnO coatings. In one specific embodiment, the superhydrophobic layer may comprise a layer of fluorinated SiO2 coating.

[0096] Not wishing to be limited by theory, the inventors have devised a method that protects the thermochromic perovskite from bulk water, such as water droplets, by employing a second layer of antireflective material as described herein and a third layer of hydrophobic material on top of a first layer of thermochromic perovskite, while allowing a preferred amount of water vapor or moisture to contact the thermochromic perovskite by reducing the water vapor / moisture transport rate. Thus, water vapor / moisture can support thermochromism (i.e., the hydration-dehydration process of the thermochromic perovskite as described herein) but triggers water / humidity-related degradation as described herein to a minimum. Therefore, it is believed that the durability of the composite material described herein will be enhanced compared to typical thermochromic perovskite materials. For example, in a specific embodiment, the composite material described herein can maintain greater than 20% solar energy regulation capability during a 45-day aging test, with a degradation rate 37 times lower than that of the original thermochromic perovskite material. Detailed performance of the composite material according to this specific embodiment will be disclosed in a later part of this disclosure.

[0097] A method for preparing the composite material as described herein will now be disclosed. The method may begin with coating a thermochromic perovskite onto a substrate made of glass or PET to form a first layer. Specifically, the coating step may be a solution-based coating method involving spin-coating or blade-coating a layer of thermochromic perovskite precursor onto the substrate. Specifically, the thermochromic perovskite precursor may be prepared by mixing AX and BX2 in a molar ratio of about 4:1 to about 7:1 in a solvent such as dimethylformamide (DMF) or dimethyl sulfoxide (DMSO), followed by stirring at a temperature of about 50°C to about 60°C for about 1 hour, wherein A is a monovalent organic cation, B is a divalent cation, and X is one or more halides as defined herein.

[0098] The thermochromic perovskite is (CH3NH3)4PbI 6-y Cl y In the embodiment of ·2H2O (where y is defined herein as 0 to 6), the precursor can be prepared by mixing CH3NH3I and PbCl2 in DMF at a molar ratio of about 6.5:1. The mixture can then be stirred at a temperature of about 50°C for about 1 hour. Afterwards, (CH3NH3)4PbI can be... 6-y Cl y The halide-based perovskite precursor ·2H2O was spin-coated onto a glass or PET substrate at a rotation speed of approximately 2000 rpm for approximately 1 hour.

[0099] Optionally, the substrate can be cleaned with suitable reagents or solvents (such as detergents, ethanol, deionized water, etc.) and / or with a plasma cleaner.

[0100] After the thermochromic perovskite is coated onto the substrate, it can be annealed. Specifically, the annealing step can facilitate the removal (evaporation) of residual solvent from the precursor. In the above embodiment where the solvent is DMF, the annealing process can be carried out at approximately 100°C for approximately 1 hour.

[0101] The next step of this method may be to coat an antireflective material onto the first layer to form a second layer. Specifically, the coating step may be a solution-based coating method involving spin-coating or blade-coating a layer of antireflective material onto a substrate. The antireflective material may comprise a homogeneous inorganic material that is cured after spin-coating or blade-coating onto the first layer. For example, in an embodiment where the antireflective material is a perhydropolysilazane, the homogeneous inorganic material can be formed by dissolving the perhydropolysilazane (e.g., in an amount of 20 wt.%) in a solvent (e.g., dibutyl ether) to form a precursor solution. The precursor solution can then be spin-coated or blade-coated onto the first layer of the thermochromic perovskite. The coated precursor solution can then be cured by curing it at a temperature of about 100°C for about 2 hours. Therefore, SiO₂ can be formed on the first layer of the thermochromic perovskite. x / SiON x A homogeneous inorganic material layer.

[0102] The method can finally proceed to the step of coating a second layer with silica-based nanoparticles to form a third layer. Similar to the previous two coating steps described above, the silica-based nanoparticle coating step is a solution-based coating method, but preferably ultrasonic spraying. Ultrasonic spraying is believed to be advantageous in that: 1) spraying produces large-area films with excellent uniformity compared to other coating methods (such as spin coating and dip coating); and 2) while coating the silica-based nanoparticle solution, the ultrasonic machine can atomize the solvent in the silica-based nanoparticle solution, thereby minimizing damage to the thermochromic perovskite caused by any functional groups of the solvent (e.g., the -OH group of ethanol).

[0103] For example, in embodiments where the silica-based nanoparticles can be SiO2 nanoparticles, particularly fluorinated SiO2 nanoparticles, the nanoparticles can be deposited onto a second layer by ultrasonically spraying a solution of SiO2 nanoparticles, such as an ethanol solution of SiO2 nanoparticles, using an ultrasonic sprayer. Specifically, the ultrasonic sprayer can simultaneously atomize the solvent in the SiO2 nanoparticle solution during the coating process. Optionally or additionally, the sample stage of the machine on which the composite material comprising the first and second layers described above is placed can be set to a preferred temperature to further promote solvent evaporation on the second layer. It should be understood that the preferred temperature can vary depending on the solvent used in the SiO2 nanoparticle solution. For example, in embodiments where the solvent is ethanol, the temperature of the sample stage can be from about 50°C to about 60°C.

[0104] The present invention will now be described in more detail through examples, but the present invention is not limited thereto.

[0105] Example

[0106] Materials and chemicals

[0107] CH3NH3I (MAI, 99.5%) was supplied by Xi'an Polymer Light Technology Corp. PbCl2 (99%) was purchased from Sigma-Aldrich. Dimethylformamide (DMF, ≥99.5%) was purchased from Alfa Aesar. PHPS was supplied by Iota Silicone Oil. Fluorinated SiO2 nanoparticles / ethanol solution was supplied by Solmont Tech.

[0108] Methods and characterization

[0109] Characterization and measurement

[0110] FTIR spectra of PHPS were obtained using PerkinElmer Spectroscopy 3. SEM images and energy-dispersive X-ray spectroscopy (EDS) spectra of the samples were obtained using FEI Quanta 450. The size of the SiO2 nanoparticles was characterized using transmission electron microscopy (TEM, 2010F, Jeol).

[0111] Transmittance spectra were obtained from 300 nm to 2500 nm using a UV-Vis-NIR spectrophotometer (Lambda 1050, Perkin Elmer equipped with a 150 mm integrating sphere detector). A specially designed temperature controller (including a heater, a type T thermocouple, and a temperature controller) was connected to the window sample to control the temperature, and transmittance was measured simultaneously in both cold (25 °C) and hot (60 °C) states.

[0112] The luminous transmittance (τ) of each window is calculated as follows: lum ):

[0113]

[0114] The amount of visible light transmitted is quantified, where τ(λ) is the transmittance of the window at wavelength λ. y(λ) is the luminous efficacy of the human eye as defined by the CIE (International Commission on Illumination) standard.

[0115] Total solar transmittance is defined as transmittance. AM 1.5 (λ) is the AM1.5G solar irradiance spectrum. Δτ sol The calculation is as follows:

[0116]

[0117] According to ASTM D1003 "Standard Method for Haze and Luminous Transmittance of Transparent Plastics", the haze is calculated as follows:

[0118]

[0119] Where T1 is the incident light, T2 is the total light transmitted through the sample, T3 is the light scattered by the device, and T4 is the light scattered by both the sample and the device. The roughness of the sample is measured using 3D surface metrology (BrukerNPFLEX).

[0120] To measure the transformation temperature T of T-perovskite c The sample was heated and cooled at 2°C intervals between room temperature and 60°C on a high-precision temperature-controlled hot plate (CHEMAT 4AH). For each temperature setpoint, the sample was held on the hot plate for 5 minutes to ensure color stability. Simultaneously, transmittance at 550 nm was measured using a lens transilluminator (SDR8508). Then, T was calculated by plotting the first derivative of transmittance with respect to temperature as a function of temperature. c T c It is the minimum point of the first derivative. The transition time is measured by observing the coloring and fading of the smart window during heating and cooling at the corresponding transition temperature point.

[0121] Water transmittance (CA) and slip angle were measured using a static CA meter (BiolinTheta), with 4 μL water droplets placed on each test surface. For durability testing, a pristine T-perovskite window (TPW) and a mask-inspired thermochromic perovskite smart window (MTPW) were placed in an enthalpy testing chamber, with the chamber conditions set to 23°C / 60%RH and 35°C / 80%RH to simulate ambient and humid / heated environments, respectively. The samples were heated and cooled once daily. Under thermal conditions, the samples were held at their transition point to simulate their actual coloration state. Transmittance was measured in both cold and hot states to determine the stability of the T-perovskite.

[0122] For Pb leakage testing, the Pb concentration in the contaminated water was detected using an ICP-MS instrument (PerkinElmer 2000). For FDTD simulation, PHPS and H-MAPbI were measured using a polarization ellipticity meter (JAWoollam RC2). 3-x Cl x (MA=CH3NH3 + The refractive index in cold and hot states. In FDTD simulations (Lumerical software), a plane wave was placed at the top as the light source to obtain the reflection and transmission spectra of the window in the wavelength range of 0.3 μm–2.5 μm. Rough H-MAPbI 3-x Cl x The PHPS layer was created based on roughness measurements obtained through 3D surface metrology. Boundary conditions along the z-direction were defined as a perfectly matched layer (PML), while symmetric boundary conditions were applied in the x and y directions. To verify the accuracy of the FDTD model, simulated transmittance of TPW and PTPW was compared with experimental results, and as shown... Figure 2 As shown, their similar transmittance spectra demonstrate the reliability of the FDTD model. Furthermore, the scattering cross-section of a single SiO2 nanoparticle was simulated to calculate its scattering efficiency. A total field scattering (TFSF) source was used as the incident light, and the boundary conditions along the x, y, and z directions were defined as PML. The mesh size was 0.5 nm. The output of the FDTD simulation is the scattering cross-section (C0) of the spherical particle. sca ), and the scattering efficiency coefficient (Q sca ) was C sca Normalization

[0123]

[0124] Where πr 2 It is the geometric cross-sectional area of ​​the scattering particle.

[0125] Example 1

[0126] Manufacturing of thermochromic perovskite smart windows (MTPW) inspired by face masks

[0127] The synthesis scheme of MTPW is in Figure 3 The diagram illustrates that the material is manufactured using a full-solution coating method.

[0128] Specifically, the glass substrate was cleaned in an ultrasonic bath with detergent, ethanol, and deionized (DI) water for 15 minutes, and then dried with N2. The glass substrate was further cleaned in a plasma cleaner (FARI GD-5) for 200 seconds. H-MAPbI 3-x Cl x Precursor (MA = CH3NH3) + H-MAPbI was synthesized as follows: MAI(CH3NH3I) and PbCl2 were mixed in DMF solvent at a molar ratio of 6.5:1, followed by stirring at 50°C for 1 hour. H-MAPbI was then spin-coated at 2000 rpm using a Laurell H6-23 spin coater. 3-x Cl x The precursor was spin-coated onto glass for 15 seconds, followed by annealing at 100°C for 1 hour to evaporate residual DMF, thereby forming a 1.6 μm thick T-perovskite film. Figure 4A The samples obtained at this stage are called T-perovskite windows (TPW).

[0129] Then, a solution of 20 wt% PHPS in dibutyl ether (a non-toxic and non-polar solvent with a low dielectric constant of 3.1) was spin-coated onto the T-perovskite layer at 500 rpm for 15 seconds, and the sample was cured in air at 100°C for 2 hours. Figure 4B Moisture and oxygen in the air cause the Si–N bonds in PHPS to break, and PHPS gradually transforms into homogeneous SiO. x / SiON x ( Figure 5 ).like Figure 6 As shown, as the curing time increases from 1 hour to 3 hours, corresponding to NH(3400cm) -1 ), Si-H (2150cm) -1 ) and Si-N (830cm -1 The Fourier transform infrared (FTIR) peak of tensile vibration decreases and approaches 1050 cm⁻¹. -1 The Si-O peaks increase. Samples obtained at this stage are referred to as PHPS-coated T-perovskite windows (PTPW).

[0130] The sample was then moved to an ultrasonic sprayer (UC 330, Siansonic Technology) to coat SiO2 nanoparticles. Ultrasonic spraying is believed to be advantageous in that: 1) it produces large-area films with excellent uniformity compared to other coating methods such as spin coating and dip coating; and 2) the ultrasonic machine can atomize the ethanol solvent in the SiO2 nanoparticle solution, thereby minimizing the damage of the -OH groups to the T-perovskite.

[0131] Specifically, superhydrophobic SiO2 nanoparticles were coated using an ultrasonic spray system (UC 330, Siansonic Technology) equipped with a 45kHz frequency nozzle (Z402, Siansonic Technology). The sample was placed on the vacuum stage of the sprayer, perpendicular to the nozzle. Specifically, the vacuum stage was set to 50°C to further accelerate the evaporation of ethanol on the perovskite surface. The concentration of the SiO2 dispersion was 1 wt.%. Details of the spraying parameters, including flow rate, forming gas pressure, distance between nozzle tip and substrate, nozzle speed, path width, number of layers, stage temperature, and ultrasonic power, are shown below.

[0132] Flow rate 0.1 ml / min Forming air pressure 0.015MPa Distance between nozzle and sample 50.0mm Nozzle speed 100mm / s Path width 4mm Number of runs 5 / 10 / 15 / 20 / 25 / 50 / 100 / 150 Base temperature 50℃ Ultrasonic power 3.0W

[0133] The thickness of each layer is controlled by layer-by-layer spray deposition. Layers are deposited in an alternating zigzag path with 4mm gaps to cover the entire surface. The sample obtained at this stage is called MTPW.

[0134] Example 2

[0135] Characterization of MTPW

[0136] Similar to medical masks, MTPW also consists of three layers. Figure 1 The bottom layer is a T-perovskite film deposited on a glass substrate. To protect the T-perovskite and maintain high window transparency, a transparent protective buffer layer is used to control the amount of water vapor on the T-perovskite, and the top layer is a superhydrophobic layer to effectively repel liquid water droplets. In this way, the T-perovskite window is like wearing a mask; the mask allows the window to "breathe" a moderate amount of water vapor to trigger thermochromic changes, but blocks excessive water vapor and droplets, thus improving its durability. (Image of MTPW follows) Figure 7 As shown, it is highly transparent in a cold state and turns reddish-brown in a hot state, and this thermochromic effect has been found to be reversible.

[0137] As shown in the figure, hydrated MAPbI 3-x Cl x (H-MAPbI of the present invention) 3-x Cl x or MA4PbI6-x Cl x ·2H2O or (CH3NH3)4PbI 6-y Cl y ·2H2O) due to its large Δτ sol (>20%), low T c T-perovskite was selected due to its high temperature (<45℃) and short t (<2 minutes).

[0138] It is believed that the protective buffer layer should be selected according to the following criteria: 1) the layer must be highly transparent; 2) the material should be stable and resistant to harsh environments; and 3) the protective buffer layer should have an n between that of perovskite and air to minimize surface reflection.

[0139] Based on the above criteria, SiO2 was selected as the protective buffer layer. It is an inorganic oxide with a refractive index (n) of approximately 1.5 (refer to H-MAPbI). 3-x Cl x Perovskites, with a visible light wavelength of n≈2.0 in the cold state and even higher in the hot state, Figure 8 At the same time, it should be understood that T-perovskites can have rough surfaces, which affect the light propagation path, thereby leading to diffuse transmission and thus high haze. Figure 9 Therefore, in addition to the three criteria mentioned above, the ability of SiO2 to form a smooth surface on T-perovskite should also be considered.

[0140] Typical SiO2 coating relies on high-vacuum cleanroom coating methods, such as chemical vapor deposition and physical vapor deposition. However, these methods require expensive deposition equipment and are only suitable for depositing conformal layers on rough surfaces, offering no benefit for filling valleys to form smooth surfaces. Figure 10A and 10B ).like Figure 10B As shown on the left, a rough surface means that sputtering methods cannot improve the surface morphology. Additionally, as... Figure 10B As shown on the right, there are brown spots on the T-perovskite surface that do not fade, indicating that the high-energy plasma may have damaged the T-perovskite during sputtering.

[0141] Therefore, the inventors designed to use solution-treated perhydropolysilazane (PHPS) to prepare the silicon oxide layer for MTPW.

[0142] PHPS is a silicone (SiH2-NH) whose framework consists of silicon and nitrogen atoms. When annealed in air, PHPS cures to produce a homogeneous inorganic SiO2. x / SiON xThe membrane exhibits better barrier properties and lower sensitivity than polymers in harsh environments. PHPS-coated glass was found to have a transmittance of approximately 90%, which is almost as high as that of bare glass because its n=1.55 is comparable to that of glass. Figure 8 and Figure 11 Using solution-based methods such as spin coating and spraying, PHPS solutions can be easily deposited, thereby smoothing the roughness of T-perovskite surfaces. Figure 12 ).

[0143] It is worth noting that perovskite-based devices typically rely heavily on antisolvent crystallization methods to achieve high-quality films. However, this method is not believed to have been successfully applied to T-perovskites. Furthermore, common antisolvents are toxic, and the dripping of antisolvents requires considerable operational experience. Compared to antisolvent methods, this study demonstrated a more environmentally friendly and convenient approach by depositing a layer of PHPS, without any toxic chemical treatments or cumbersome operational techniques. These advantages of PHPS not only protect the T-perovskite from excessive water vapor but also improve its optical transmittance.

[0144] Meanwhile, considering that in practical applications T-perovskite windows may be exposed to large volumes of water or have water droplets accumulating on their surface, it is understandable that individual PHPS (water contact angle is only about 99°) Figure 13 This indicates that it is not superhydrophobic and may not be able to protect the T-perovskite window from damage under continuous water penetration. Therefore, the inventors designed a superhydrophobic fluorinated nano silica layer to be applied to the top of the MTPW, similar to the hydrophobic spunbond fabric in a mask that blocks bodily fluids, to give it excellent water resistance.

[0145] Example 3

[0146] Optical properties of MTPW

[0147] The transmittance spectra of MTPW and TPW are shown in Figure 14 In the middle. MTPW exhibits 83.4% τ in the cold state. lum And in the hot state, it is 30.4%, where Δτ sol It is 24.4%, while TPW's τ lum The percentages in the cold and hot states are 78.2% and 28.8%, respectively, where Δτ sol It is 25.4%. It is worth noting that the τ of MTPW... lum,冷 and τ lum,热 Both are higher than TPW because less light scattering occurs at the surface, and therefore the amount of haze is reduced.

[0148] Light haze is an important parameter for windows, and it can be defined as the ratio of diffuse transmittance to the total transmittance including the specular and diffuse portions. Figure 15 Low-haze windows will provide a clear view, while high-haze windows will blur the view through light distortion, although the total transmittance remains high. Although compared to other solution-based smart windows, the original TPW has a higher τ... lum and Δτ sol It has advantages in all aspects (e.g., for VO2 thermochromic windows, τ) lum and Δτ sol Typically, these figures are approximately 50% and 10% respectively, but the high haze of TPW windows is ignored in most studies. Figure 16 As shown, the pavilion 10m away from the TPW could not be seen, while it could be clearly observed through the MTPW. Optical measurements also confirmed that the TPW had a light haze of up to 90%, while the PTPW and MTPW had significantly reduced light haze to as low as 20% and 30%, respectively. Figure 17 ).

[0149] To explain this phenomenon, the surface morphology of TPW, PTPW, and MTPW was characterized. Figure 18 TPW has a rough and uneven surface. Figure 18 (Image 1) This is attributed to excess MAI in the perovskite precursor, which affects the crystallization process. 3D morphology quantitatively determined by surface profilometer indicates that the surface roughness of TPW is Ra = 208 nm (…). Figure 18 (Image 2). However, after being coated with PHPS, the surface of the PTPW is quite flat, as shown in Figure 2. Figure 18 As shown in Figure 3, Ra is significantly reduced to 55 nm. Figure 18 (Image 4). Based on this observation, the enhanced optical performance of MTPW can be quantitatively explained as follows: Figure 19 The optical path on the T-perovskite surface is shown. Along the plane wave propagation path, different portions of the wavefront encounter rough surfaces at different heights. Therefore, the scattered components have a phase difference. The phase difference for the components transmitted from point A on the rough and flat surfaces at the average height [h] is:

[0150]

[0151]

[0152] Δh=h A -[h],(c)

[0153] Where k is the wavenumber in vacuum, Δh is the height variation around the average height [h] of the rough surface, and n is the refractive index of the medium. According to the Rayleigh roughness standard, the standard deviation of the phase difference should be less than π / 2 to ensure constructive interference (i.e., specular transmission). In this case, the surface can be considered slightly rough or even flat. To satisfy the Rayleigh roughness standard, based on equations (a)-(c), the following must hold:

[0154]

[0155] Equation (d) shows that when the refractive indices of the two media are relatively close, the tolerance to RMS is greater, and vice versa. When light encounters peaks and valleys, the rough surface of TPW and the large refractive index difference between air (n≈1.0) and T-perovskite (n≈2.0) both cause strong scattering, resulting in high haze and reduced specular transmittance. Compared to air, the n value of PHPS is relatively close to that of perovskite. Therefore, using PHPS at the top can improve the tolerance of the light propagation path to surface roughness (Equation (d)), thereby reducing light scattering at the T-perovskite surface boundary. In addition, the n value of PHPS is between that of air and T-perovskite, and it can also act as an anti-reflective layer to improve the overall transmittance.

[0156] To verify the above explanation, we performed finite-difference time-domain (FDTD) simulations to analyze light propagation through different surfaces. The model built using FDTD software is shown below. Figure 20 As shown. PHPS and T-perovskite (H-MAPbI) were measured using an elliptometer. 3-x Cl x Complex refractive index in cold and hot states, such as Figure 8 As shown. Figure 21 The light propagation process at the air / window interface is shown for ideal smooth TPW, rough TPW, and PTPW.

[0157] For an ideal TPW, the direction of light propagating along the normal does not change at the air / window interface. Figure 21 (Image 1), resulting in high specular transmittance and low haze. However, if the TPW surface is rough (TPW roughness data is taken from...), it will result in high specular transmittance and low haze. Figure 18 (Image 2) The propagation path of light will be significantly altered at the air / TPW interface due to strong scattering. Figure 21 Image 2), resulting in increased diffuse reflection and transmission. PHPS was deposited on a rough TPW surface (roughness data of PHPS were obtained from...). Figure 18 After (Figure 4), most of the light retains its original path along the normal direction, and scattering at the T-perovsk surface is significantly suppressed compared to the rough TPW. Figure 21 (Image 3). When comparing Figure 21 Image 2 and Figure 21 In Image 3, it was noted that the reflected field intensity above the air / window surface decreased after PHPS coating. Simulated reflectance spectra further confirmed that the reflectance on the TPW decreased from 11.8% to 6.8%. Figure 22 This desired reduction in reflectivity is caused by the antireflective effect of the PHPS layer, resulting in τ lum Increase( Figure 2 ).

[0158] Furthermore, the angular distribution of scattered light in the reflection and transmission fields of rough TPW and smooth PTPW was extracted from FDTD simulations based on the two-way scattering distribution function (BSDF). BSDF can characterize light scattering at the surface in a radiometric manner as a function of the angular positions of the incident and scattered beams. The scattered light distribution in the transmission and reflection fields of the rough TPW surface spans a relatively wide angular range (…). Figure 23 This results in a blurred visual effect. Conversely, for PTPW surfaces, both transmitted and reflected light are concentrated within a smaller angular range (…). Figure 24 This results in a clearer field of view. In summary, the top PHPS layer is believed to benefit the optical performance of the TPW in two ways: by smoothing the originally rough surface, it significantly reduces haze, and by improving overall transparency through anti-reflective effects.

[0159] The top layer of the MTPW is a superhydrophobic layer of nanoparticles used to achieve water resistance. SiO2 is believed to have the lowest refractive index in the visible light range (1.45) among nanoparticles in this field, and was therefore chosen to minimize light scattering. Furthermore, according to Mie scattering theory, particle size also affects the scattering efficiency (Q...). s ). Using FDTD simulations to measure the Q of SiO2 nanospheres s Calculated as a function of particle size across the solar spectrum ( Figure 25 ). Figure 26 The display shows that Q s It decreases as the diameter decreases. When the diameter is 20 nm, Q... s The size is very small, indicating a limited impact on optical performance. Therefore, SiO2 nanoparticles with a diameter of 20 nm were chosen for the fabrication of MTPWs (Figure S27). Figure 28 As shown, the transmittance spectrum of MTPW is almost identical to that of PTPW without SiO2 nanoparticles. Due to the increase in roughness, the haze increases only slightly. Figure 17 , Figure 18 (Images 5 and 6).

[0160] Example 4

[0161] Transformation properties of MPTW

[0162] For thermochromic smart windows, it should be understood that in addition to their excellent optical performance, they also need to include a low transition temperature (T0). c The transformation properties, including short transition time (t), were investigated. Therefore, the transformation properties of MTPW were studied. Specifically, the transformation properties during heating (T0) were investigated. c,h ) and cooling (T c,c During the process, the PHPS layer and SiO2 nanoparticles affect H-MAPbI 3-x Cl x The relatively low T of perovskite c The impact.

[0163] like Figure 29 As shown, the temperature-dependent transition processes of TPW and MTPW are almost identical. The temperature-dependent transition process of the original TPW is... c,h and T c,c The calculated values ​​were 43.2℃ and 35.6℃, while the calculated values ​​for MTPW were 43.4℃ and 35.9℃, which means that the coating affects T... c No impact. Additionally, as... Figure 30 As shown, the original TPW completed its color transition within 65 seconds and 120 seconds during heating and cooling, respectively. For MTPW, due to the limitation of water vapor transport rate by the PHPS and SiO2 nanoparticle layers, the transition time during heating and cooling inevitably increased to 120 seconds and 300 seconds, respectively, which is still considered acceptable for practical applications.

[0164] Example 5

[0165] MTPW's superhydrophobicity and long-term stability

[0166] The wettability of the original TPW and PTPW was compared, and the results are shown in... Figure 31A and 31B In the figure, the original TPW is hydrophilic with an initial contact angle (CA) of 21.2°, and the T-perovskite film is immediately damaged by water droplets. Figure 32 The CA value decayed to 12.4° within 1 second and could not be measured by a CA meter after 3 seconds, indicating severe water corrosion. PTPW exhibited a higher CA of 98.4°, but the CA rapidly decreased to 54.1° after 9 minutes. Both TPW and PTPW showed poor hydrophobicity and were unable to effectively repel water from the window surface. Therefore, the superhydrophobic characteristics of T-perovskite smart windows should be realized to physically block harmful moisture and water.

[0167] As described above, superhydrophobic SiO2 nanoparticles with a diameter of 20 nm were coated on the PHPS layer. Figure 33SEM images of the surface of SiO2 nanoparticles at different spin-coating cycles are shown. As the number of spin-coating cycles increases, the packing density of SiO2 nanoparticles increases, and when the number of cycles exceeds 25, the surface is almost completely covered by SiO2 nanoparticles. Figure 34 The effect of the number of spraying cycles on the coefficient of friction (CA) was shown, with an upward trend observed from 115.3° after 5 cycles to 160.8° after 50 cycles. After 50 cycles, the CA remained almost unchanged, or even decreased slightly. This can be attributed to the fully covered SiO2 nanoparticles, which lead to an increased area of ​​the liquid-solid interface, resulting in higher surface adhesion. Furthermore, the slip angle of the MTPW was only 5.7° after 50 cycles, which is beneficial for windows. Therefore, the optimal SiO2 spraying scheme is recommended to be 50 cycles. After the deposition of SiO2 nanoparticles, the MTPW exhibited superhydrophobicity with a stable CA above 160°. Figure 31A When stained droplets are placed on the surface of MTPW, the droplets spread into a compressed disk shape and eject from the surface, indicating outstanding superhydrophobicity. Figure 35 This excellent superhydrophobic property enables MTPW to effectively repel water and prevent the degradation of T-perovskite by large-volume water. Furthermore, a water jet test was conducted to verify the water-repellent capability of MTPW. MTPW was placed under a tap and rinsed with high-speed water (flow rate: approximately 4.7 m / s). The T-perovskite remained intact, and it still exhibited reversible color-changing ability during heating and cooling, demonstrating the excellent water-repellent properties of MTPW (data not shown).

[0168] The durability of MTPWs was investigated by evaluating their optical stability. Specifically, the long-term optical performance of the MTPWs was examined through moisture resistance tests at different relative humidity (RH) levels. To precisely control environmental conditions, the experiment was conducted within an environmental testing chamber. (Micro-testing)

[0169] like Figure 36A and 36B As shown, during the aging test at 60% RH, all characteristics of TPW, including τ lum,冷 τ lum,热 and Δτ sol This shows a clear decreasing trend. Specifically, τ lum,热 It increased significantly from 28.8% to 68.8% within five days, resulting in Δτ sol The percentage dropped sharply from 23.1% to 4.8%, indicating a loss of thermochromic properties. In stark contrast, the MTPW maintained stable optical performance over 40 days, and Δτ solThe aging performance remained above 20% on day 45 of the aging test. The significantly enhanced durability is attributed to the strong protection of the PHPS and SiO2 superhydrophobic layers, which protects the T-perovskite membrane from continuous permeation by large amounts of water vapor. Under higher water vapor concentrations of 80% RH... Figure 37A TPW degraded rapidly within just half a day, of which τ lum,热 Increased to 54.6% and Δτ sol Only 8.5%. Even though high humidity affected MTPW, it still maintained a relatively stable τ after 20 days of aging testing. lum,冷 and τ lum , 热 And an acceptable Δτ of approximately 20%. sol ( Figure 37B By comparing Δτ sol decay rate ( Figure 38A and 38B The study found that the lifespan of the MTPW was significantly extended by 37 times in normal ambient conditions and by 98 times in humid environments compared to the original TPW, making it reliable for practical applications.

[0170] Due to the water vulnerability of T-perovskite films, Pb leakage has attracted widespread attention. During the thermochromic process, the T-perovskite undergoes a water-induced phase transition from a hot state of MAPbX3 to a cold state of MA4PbX6·2H2O, resulting in a size reduction. The formed low-dimensional dihydrated perovskite is further decomposed, as shown in the following equation:

[0171]

[0172] The presence of strong hydrogen bonds between water molecules and toxic PbX2 results in a high solubility constant (K₂) of PbX2 in water. sp = Approximately 10 -8 This caused a serious Pb leak, threatening the environment and human health. To investigate the Pb leak, both the original TPW and MTPW were immersed in deionized water. Figure 39A As shown, the original TPW immediately turns yellow within 1 second, which means Pb leakage. Figure 39B The X-ray diffraction (XRD) pattern of the yellow film shown demonstrates that the T-perovskite film decomposed into PbI2. In contrast, the MTPW remained transparent underwater for up to 5 minutes. Furthermore, the color changed upon heating, indicating that the T-perovskite was well preserved and the thermochromic effect was maintained. To further estimate the Pb content in the contaminated water... 2+ The amount of ions was measured by inductively coupled plasma mass spectrometry (ICP-MS), such as... Figure 39C As shown. Pb of the original TPW 2+The concentration reached 4.023 mg / L within 30 minutes, which is 66 times that of MTPW (0.061 mg / L). These results strongly demonstrate that superhydrophobic MTPW can immobilize Pb. 2+ It also reduces Pb leakage, making MTPW more environmentally friendly.

[0173] Example 6

[0174] Applications of MTPW

[0175] Compared to the original TPW, MTPW exhibits better moisture and water resistance while showing less lead leakage. Furthermore, the all-solution-based manufacturing process, which requires no additional toxic antisolvents, offers potential for scalability. These advantages allow MTPW to be directly manufactured as flexible window films without the need for sealing, making it more convenient and cost-effective for practical applications and installations. Here, a highly flexible MTPW film was achieved by sequentially coating T-perovskite, PHPS, and SiO2 nanoparticles onto a PET film. Figure 40A ).

[0176] With widely used dark ( Figure 40B Compared to commercially available energy-saving window films that can block some visible and near-infrared light to consistently reduce indoor solar thermal gain even in cold weather, the solar transmittance of the MTPW film of this invention dynamically adjusts with temperature changes, maintaining a useful solar thermal gain in cold weather / seasons but reducing harmful solar thermal gain in hot weather / seasons. Figure 40C Therefore, MTPW is expected to have better year-round energy-saving capabilities than traditional energy-saving window films.

[0177] To compare energy-saving performance, commercial window film and MTPW film were used in five cities in the United States. Figure 40A and 40B EnergyPlus modeling was performed on the commercial building. Figure 41 Basic building information is listed in Figure 42 The table shown uses the WINDOW algorithm developed by Lawrence Berkeley National Laboratory to calculate the normal window, the window with commercial film, and the window with MTPW film used in the simulation. Figure 43 Optical information () Figure 44 Climate information for each city is listed below. Figure 45 The table shown.

[0178] In summary, EnergyPlus modeling of typical U.S. cities demonstrates that the use of MTPW membranes shows greater energy-saving potential than commercial membranes, especially in northern regions where buildings also have high heating needs during winter. Figure 46 and 47(For example, the use of traditional window film resulted in only 0.4% energy savings in Philadelphia, and even more in New York (about 1.9%).)

[0179] In particular, taking Philadelphia as an example, buildings with traditional window film consume significantly more heating energy than buildings with ordinary windows, especially during the winter months from November to March. Figure 48 This ultimately offsets the cooling energy saved in hot weather. Figure 49 Conversely, due to its intelligent thermal response color-switching capability, MTPW maintains high solar thermal gain in cold weather but low solar transmittance in hot weather. Therefore, heating demand when using MTPW film does not change significantly compared to heating demand when using normal windows in winter, while cooling demand drops sharply during transitional seasons and the summer months of April to October. Figure 48 This demonstrates the advantages of intelligent optical adjustment. In hot regions (e.g., Orlando), windows with both MTPW and commercial window film exhibited better energy efficiency than standard windows. Figure 50 and 51 Furthermore, due to its lower solar transmittance, MTPW windows exhibit better performance.

[0180] In summary, the above results demonstrate that MTPW window film is promising in reducing annual energy consumption in HVAC systems, and its application as a smart energy-saving window film is also promising.

[0181] The invention is given by way of example only, and various other modifications and / or alterations may be made to the described embodiments by those skilled in the art without departing from the scope of the invention as specified in the appended claims.

Claims

1. A composite material comprising: The first layer of the thermochromic perovskite has a surface; A second layer of antireflective material, having a surface and comprising an organic or inorganic polymer, is deposited on the surface of the first layer; and A third layer of hydrophobic material is deposited on the surface of the second layer; in, The second and third layers are configured to allow a controlled amount of water vapor to reach the first layer, thereby causing the first layer to hydrate and dehydrate to support the thermochromic effect of the first layer, and wherein, after the thermochromic effect, the first, second and third layers all remain transparent.

2. The composite material of claim 1, wherein the first layer comprises a substrate made of glass or PET, on which a thermochromic perovskite layer is deposited.

3. The composite material of claim 2, wherein the thickness of the thermochromic perovskite layer is 1.6 μm.

4. The composite material of claim 1, wherein the thermochromic perovskite comprises a material having the general formula A4BX6. A halide-based perovskite compound of 2H2O, wherein A is a monovalent organic cation, B is a divalent cation, and X is one or more halides.

5. The composite material as described in claim 4, wherein A4BX6 2H2O can be reversibly converted into ABX3 in response to temperature changes.

6. The composite material as described in claim 5, wherein A is selected from CH3NH3. + and CH(NH2)2 + Any of the following; B is selected from Pb 2+ 、 Sn 2+ 、Ge 2+ Mg 2+ and Ca 2+ Either of the following; and X is selected from I. - ,Br - Cl - and any combination thereof.

7. The composite material of claim 6, wherein the halide-based perovskite compound has the general formula (CH3NH3)4PbI 6-x-y Br x Cl y 2H2O, where x and y are each 0 or positive integers, and x+y ≤ 6.

8. The composite material of claim 7, wherein the halide-based perovskite compound is (CH3NH3)4PbI 6-y Cl y 2H2O, where y is 0 to 6.

9. The composite material of claim 1, wherein the antireflective material has a refractive index between that of air and the thermochromic perovskite.

10. The composite material of claim 9, wherein the antireflective material comprises any one of the following: epoxy resin, poly(methyl methacrylate), polyvinylpyrrolidone, poly(vinyl alcohol), polydimethylsiloxane, poly(acrylic acid), poly(acrylamide), poly(aniline), poly(ethylene oxide), poly(N-acryloyloxysuccinimide), poly(N-isopropylacrylamide), poly(N-isopropylmethylacrylamide), poly(N-vinylcaprolactam), poly(methacrylic acid), poly(styrene sulfonic acid), polyurethane, poly(propylene oxide), perhydropolysilazane, or combinations thereof.

11. The composite material of claim 10, wherein the antireflective material is a perhydropolysilazane.

12. The composite material of claim 11, wherein the perhydropolysilazane is in the form of SiO₂. x / SiON x It takes the form of a homogeneous inorganic membrane.

13. The composite material of claim 1, wherein the hydrophobic material comprises a superhydrophobic layer.

14. The composite material of claim 13, wherein the superhydrophobic layer comprises a layer of fluorinated nanocoating.

15. The composite material of claim 14, wherein the fluorinated nanocoating layer is any one of fluorinated SiO2, fluorinated TiO2, and fluorinated ZnO.

16. A method for preparing the composite material as described in claim 1, the method comprising the following steps: Thermochromic perovskite is coated onto a substrate made of glass or PET to form the first layer; A second layer is formed by coating an anti-reflective material onto the first layer. as well as A third layer is formed by coating the second layer with silica-based nanoparticles.

17. The method of claim 16, wherein the thermochromic perovskite is annealed after it is coated on the substrate to form the first layer.

18. The method of claim 17, wherein the thermochromic perovskite is (CH3NH3)4PbI 6-y Cl y The halide-based perovskite precursor 2H2O, where y is 0 to 6, is prepared by mixing CH3NH3I and PbCl2 in a molar ratio of 6.5:

1.

19. The method of claim 17, wherein the annealing is at 100°C. Perform for 1 hour under C.

20. The method of claim 16, wherein the antireflective material comprises a homogeneous inorganic material, the homogeneous inorganic material being cured by spin coating or scraping onto the first layer.

21. The method of claim 20, wherein the homogeneous inorganic material is prepared from a perhydropolysilazane dissolved in dibutyl ether.

22. The method of claim 16, wherein the first layer, the second layer and the third layer are formed by a solution-based coating method.

23. The method of claim 22, wherein the first layer and the second layer are formed by spin coating.

24. The method of claim 23, wherein the third layer is formed by ultrasonic spraying.

25. The method of claim 24, wherein the silica-based nanoparticles are SiO2 nanoparticles, which are deposited on the second layer by simultaneously coating a solution of the SiO2 nanoparticles with ultrasonic spraying and atomizing the solvent in the solution.

Images