Thermochromic liquid-filled smart window and method of making same

Abstract

This invention relates to the field of building energy conservation and smart window technology, specifically to a thermochromic liquid-filled smart window and its preparation method. The smart window includes a first transparent substrate, a second transparent substrate, and a liquid thermochromic layer sandwiched between the two. The liquid thermochromic layer comprises a thermochromic system composed of an antimony source, a sulfur source, an alkylamine, and an alkyl thiol. The thermochromic system is based on the reversible growth and dissolution mechanism of antimony sulfide nanosheets triggered by temperature. It exhibits a highly transparent and colorless state at low temperatures, transforms into a colored state during heating to regulate solar radiation, and returns to transparency after cooling. This smart window also possesses high visible light transmittance (T0). lum Up to 95.0%), strong solar radiation modulation capability (ΔT' sol (78.0%), low thermal conductivity (0.17 W·m) ‑1 ·K ‑1 With its excellent physical and chemical stability, it provides an efficient, passive, and long-life solution for the photothermal management of green buildings.

Description

Technical Field

[0001] This invention relates to the field of building energy conservation and smart window technology, and in particular to a thermochromic liquid-filled smart window and its preparation method. Background Technology

[0002] Building windows play an irreplaceable role in achieving natural lighting and visual connectivity within buildings. However, as a weak link in the thermal performance of the building envelope, the cooling and heating loads caused by windows account for a significant proportion of the building's total energy consumption. With the increasing prevalence of curtain walls in modern buildings, the energy consumption issues related to cooling and heating caused by windows are becoming increasingly prominent.

[0003] To balance lighting needs and energy consumption control, smart window technology has seen rapid development. Smart windows can respond to changes in the external environment, dynamically adjusting solar radiation transmittance to achieve coordinated optimization of the indoor light and heat environment. Existing smart windows mainly include thermochromic windows, electrochromic windows, photochromic windows, and mechanochromic windows. Among them, thermochromic windows automatically switch light transmittance based on temperature-responsive materials, requiring no external energy source, making them suitable for a wide range of scenarios and offering significant advantages in the field of passive energy-efficient buildings.

[0004] Among existing thermochromic materials, vanadium dioxide (VO2) and poly(N-isopropylacrylamide) (PNIPAM) hydrogels have been studied in greater depth. Vanadium dioxide-based smart windows regulate near-infrared light transmittance through metal-insulator phase transitions, but typically suffer from low visible light transmittance and limited modulation of solar radiation. PNIPAM hydrogels achieve full-spectrum modulation of sunlight through thermosensitive phase transitions, but generally exhibit high optical haze, insufficient thermal cycling stability, and poor long-term environmental weather resistance.

[0005] In the process of realizing this invention, the inventors discovered that the prior art has at least the following problems: the existing thermochromic liquid-filled smart windows cannot simultaneously achieve high visible light transmittance, low haze, wide-band solar radiation modulation capability and long-term operational stability, resulting in a tradeoff between energy-saving effect and visual comfort, which limits their large-scale application in the field of building energy conservation.

[0006] Therefore, the existing technology needs further improvement. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the purpose of this invention is to provide a thermochromic liquid-filled smart window and its preparation method, aiming to solve the problems of low visible light transmittance and insufficient solar radiation regulation capability of existing thermochromic smart windows.

[0008] The technical solution of the present invention is as follows: In a first aspect, a thermochromic liquid-filled smart window includes a first transparent substrate, a second transparent substrate, and a liquid thermochromic layer sandwiched between the first transparent substrate and the second transparent substrate. The liquid thermochromic layer is composed of a thermochromic system formed by an antimony source, a sulfur source, an alkylamine, and an alkyl thiol.

[0009] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0010] Preferably, in the thermochromic liquid-filled smart window, the antimony source is selected from one or more of antimony acetate, antimony trichloride, and antimony trioxide; Preferably, the antimony source is antimony acetate.

[0011] Preferably, in the thermochromic liquid-filled smart window, the sulfur source is selected from one or more of sulfur powder, sodium sulfide, and thiourea; Preferably, the sulfur source is sulfur powder.

[0012] Preferably, in the thermochromic liquid-filled smart window, the alkylamine is selected from one or more of oleylamine, butylamine, and octylamine; The alkyl thiol is one or more of n-dodecyl thiol, n-octyl thiol, or n-decyl thiol.

[0013] Preferably, in the thermochromic liquid-filled smart window, the volume ratio of the alkylamine to the alkylthiol is 3:1 to 1:3; Preferably, the volume ratio of the alkylamine to the alkylthiol is 1:1.

[0014] Preferably, in the thermochromic liquid-filled smart window, during the heating process, antimony sulfide, an active component, is generated in the liquid thermochromic layer, and the concentration of the active component antimony sulfide is 0.87~8.75 mM. Preferably, the concentration of the active component antimony sulfide is 4.37~8.75 mM; more preferably, the concentration of the active component antimony sulfide is 6.56 mM.

[0015] Preferably, in the thermochromic liquid-filled smart window, the visible light transmittance T of the liquid thermochromic layer at 20 °C is... lum It is over 90%; Preferably, the visible light transmittance T of the liquid thermochromic layer at 20 °C is... lum The value is 95.0%; the solar radiation modulation capability ΔT' of the liquid thermochromic layer at 80 °C is...sol It is over 70%; Preferably, the liquid thermochromic layer has a solar radiation modulation capability ΔT' at 80 °C. sol It is 78.0%.

[0016] Secondly, a method for preparing a thermochromic liquid-filled smart window as described above includes the following steps: Antimony source and sulfur source are added to a mixed solvent composed of alkylamine and alkylthiol to obtain a precursor solution; The precursor solution was heated to obtain a liquid thermochromic system; The liquid thermochromic system is cooled and then poured into a sandwich structure formed by a first transparent substrate and a second transparent substrate; The sandwich structure is sealed to obtain the thermochromic liquid-filled smart window.

[0017] Preferably, in the method for preparing the thermochromic liquid-filled smart window, the heating temperature is 80~120 °C; and the heating time is 5~30 min. Preferably, the heating temperature is 100 °C; Preferably, the heating time is 10 minutes.

[0018] Thirdly, the application of a thermochromic liquid-filled smart window, as described above, in energy-saving control of building envelope.

[0019] Optionally, the first transparent substrate and the second transparent substrate are quartz glass or architectural transparent glass.

[0020] Optionally, the thickness of the liquid thermochromic layer is 0.5~2.0 cm; preferably, the thickness of the liquid thermochromic layer is 1.0 cm.

[0021] Optionally, the visible light transmittance T of the liquid thermochromic layer at 20 °C lum The transmittance is above 90%; preferably, the visible light transmittance T of the liquid thermochromic layer at 20 °C is... lum It is 95.0%.

[0022] Optionally, the solar radiation modulation capability ΔT' of the liquid thermochromic layer at 80 °C sol The solar radiation modulation capability ΔT' of the liquid thermochromic layer at 80 °C is above 70%; preferably, the solar radiation modulation capability ΔT' of the liquid thermochromic layer at 80 °C is... sol It is 78.0%.

[0023] Optionally, the thermal conductivity of the liquid thermochromic layer is 0.17 W·m. -1 ·K-1 .

[0024] Optionally, the liquid thermochromic layer retains more than 90% of its light transmittance adjustment capability after 1000 heating / cooling cycles.

[0025] Secondly, the present invention provides a method for preparing a thermochromic liquid-filled smart window, comprising the following steps: Antimony source and sulfur source are added to a mixed solvent composed of alkylamine and alkylthiol to obtain a precursor solution; The precursor solution was heated to obtain a liquid thermochromic system; The liquid thermochromic system is cooled and then poured into a sandwich structure formed by a first transparent substrate and a second transparent substrate; The sandwich structure is sealed to obtain the thermochromic liquid-filled smart window.

[0026] Optionally, the heating temperature is 80~120 °C; Preferably, the heating temperature is 100 °C.

[0027] Optionally, the heating time is 5 to 30 minutes; Preferably, the heating time is 10 minutes.

[0028] Optionally, the sandwich structure is formed by assembling with nano-residue-free adhesive; The seal is achieved by using UV-curable adhesive for edge sealing.

[0029] Thirdly, the present invention provides an application of a thermochromic liquid-filled smart window in energy-saving control of building envelope.

[0030] Optionally, the building envelope includes one or more of the following: building windows, glass curtain walls, skylights, and transparent enclosure structures.

[0031] Optionally, the thermochromic liquid-filled smart window is used to adjust solar radiation transmittance, reduce building cooling load, and / or improve building thermal insulation performance.

[0032] Beneficial effects: Compared with existing technologies, this invention is based on the reversible growth and dissolution mechanism of antimony sulfide nanosheets in a liquid thermochromic layer triggered by temperature. It exhibits a highly transparent, colorless state at low temperatures, transforms into a colored state during heating to regulate solar radiation, and returns to transparency after cooling. This smart window also possesses high visible light transmittance (T0). lum Up to 95.0%), strong solar radiation modulation capability (ΔT' sol (78.0%), low thermal conductivity (0.17 W·m) -1 ·K -1With its excellent physical and chemical stability, it provides an efficient, passive, and long-life solution for the photothermal management of green buildings. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the structure of the thermochromic liquid-filled smart window of the present invention.

[0035] Figure 2 This is a photograph of the liquid thermochromic system of the present invention during the heating process.

[0036] Figure 3 These are TEM images of the quenching products of the liquid thermochromic system of this invention at different temperatures.

[0037] Figure 4 This is an elemental distribution diagram of the product of the liquid thermochromic system of the present invention at 100 °C.

[0038] Figure 5 The XRD patterns of the quenching products of the liquid thermochromic system of the present invention at different temperatures are shown.

[0039] Figure 6 Photographs of alkylamine / alkylthiol mixtures with different volume ratios at 20 °C and 80 °C.

[0040] Figure 7 TEM images of the quenching products of alkylamine / alkylthiol mixtures with different volume ratios at 100 °C.

[0041] Figure 8 A photograph of a physical object showing the restoration of thermochromic effects after the products of high-temperature quenching have been redispersed.

[0042] Figure 9 This is a comparison diagram showing the results of systems with different antimony and sulfur sources.

[0043] Figure 10 This is a schematic diagram of the preparation process of the thermochromic liquid-filled smart window of the present invention.

[0044] Figure 11 Photos of the mass-produced liquid thermochromic system at 20 °C and 80 °C.

[0045] Figure 12This is a comparison chart of the viscosity of different liquids.

[0046] Figure 13 These are actual photos of the smart window of this invention at 20 °C and 80 °C.

[0047] Figure 14 Transmittance spectra of single-layer glass, laminated glass, and the smart window of this invention.

[0048] Figure 15 The photos show the actual smart window in the 0~80 °C range.

[0049] Figure 16 The transmittance spectrum of the smart window in the range of 0~80 °C.

[0050] Figure 17 This is a graph showing the changes in haze and transmittance of the smart window within the temperature range of 0~80 °C.

[0051] Figure 18 The graph shows the transmittance of samples with different concentrations at a wavelength of 1000 nm as a function of temperature.

[0052] Figure 19 Transmittance spectra of smart windows with different interlayer thicknesses at 20 °C and 80 °C.

[0053] Figure 20 The graphs show the changes in thermal conductivity and specific heat capacity of different filling systems with temperature.

[0054] Figure 21 This is a cyclic stability diagram of the smart window of the present invention.

[0055] Figure 22 Infrared thermal images and temperature rise curves of different filled windows under actual sunlight.

[0056] Figure 23 This is a diagram showing the results of outdoor temperature control testing of the model chamber.

[0057] Figure 24 This is a photograph of a large-sized thermochromic liquid-filled smart window. Detailed Implementation

[0058] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0059] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0060] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0061] like Figure 1 As shown, this embodiment provides a thermochromic liquid-filled smart window, including a first front transparent substrate 10, a second rear transparent substrate 20, and a liquid thermochromic layer 30 sandwiched between the two; the liquid thermochromic layer includes a thermochromic system formed by an antimony source, a sulfur source, an alkylamine, and an alkyl thiol.

[0062] In this embodiment, the liquid thermochromic layer is initially colorless and transparent. As the temperature rises, antimony sulfide nanosheets are gradually generated in the system, causing the liquid thermochromic layer to change from colorless and transparent to a colored state, thereby significantly reducing solar radiation transmittance. When the temperature decreases, the generated antimony sulfide nanosheets dissolve again, and the liquid thermochromic layer returns to its colorless and transparent state. The thermochromic liquid-filled smart window of this invention does not affect building lighting and views at low temperatures, while actively blocking solar radiation from entering the room under high-temperature conditions, exhibiting excellent lighting, heat insulation, and energy-saving effects.

[0063] In some embodiments, the antimony source is one or more of antimony acetate (Sb(Ac)3), antimony trichloride (SbCl3), and antimony trioxide (Sb2O3), preferably antimony acetate. Antimony acetate has good solubility in binary solvents and is conducive to forming a transparent precursor solution, thereby ensuring high transmittance of the smart window at low temperatures.

[0064] In some embodiments, the sulfur source is one or more of sulfur powder (S), sodium sulfide (Na2S), and thiourea (CH4N2S). When sulfur powder is used, the resulting thermochromic system remains colorless and transparent at low temperatures and forms antimony sulfide nanosheets with excellent thermochromic properties during the heating process.

[0065] In some embodiments, the alkylamine is one or more of oleylamine, butylamine, or octylamine; The alkyl thiol is one or more of n-dodecyl thiol, octyl thiol, or decanethiol; exemplarily, the alkylamine is oleylamine, and the alkyl thiol is n-dodecyl thiol.

[0066] It should be noted that alkylamines and alkyl thiols together constitute a binary solvent system in this invention. Both not only act as solvents but also participate in coordination, proton transfer, and intermediate formation processes, playing a crucial regulatory role in the nucleation, growth, and dissolution of antimony sulfide nanosheets. Without either component, the system struggles to exhibit stable and reversible thermochromic behavior.

[0067] In some embodiments, the volume ratio of the alkylamine to the alkylthiol is 3:1 to 1:3. When the volume ratio of oleylamine to n-dodecyl mercaptan is 1:1, the system is conducive to the formation of antimony sulfide nanosheets at high temperatures and to the redissolution of the nanosheets at low temperatures, thus obtaining the best reversible thermochromic properties.

[0068] In some embodiments, the concentration of the active component Sb₂S₃ in the liquid thermochromic layer is 0.87~8.75 mM, such as 4.37~8.75 mM, or 6.56 mM. By adjusting the concentration of the active component Sb₂S₃, the thermochromic temperature range and optical adjustment capability can be controlled. At lower concentrations, the coloring at high temperatures is weaker; at higher concentrations, significant thermochromism can occur at lower temperatures.

[0069] In some embodiments, the first transparent substrate and the second transparent substrate are quartz glass or architectural transparent glass.

[0070] In some embodiments, the thickness of the liquid thermochromic layer is 0.5~2.0 cm, such as 1.0 cm. Increasing the thickness of the interlayer enhances the ability to block solar radiation at high temperatures, but at the same time affects some low-temperature transparency. Therefore, a thickness of 1.0 cm is preferred to balance light transmission and modulation performance.

[0071] In some embodiments, the visible light transmittance T of the liquid thermochromic layer at 20 °C lum The solar radiation modulation capability ΔT' at 80 ℃ is above 90%, such as 95.0%; solThe percentage is over 70%, such as 78.0%. The smart window of this invention combines high transparency and high modulation capability, which is significantly better than most existing thermochromic window materials.

[0072] In some embodiments, the thermal conductivity of the liquid thermochromic layer is 0.17 W·m. -1 ·K -1 The low thermal conductivity of this invention enables the smart window to provide not only dimming but also heat insulation and heat preservation.

[0073] In some embodiments, the liquid thermochromic layer retains more than 90% of its light transmittance adjustment capability after 1000 heating / cooling cycles, demonstrating that the system of the present invention has excellent long-term stability.

[0074] This embodiment also provides a method for preparing a thermochromic liquid-filled smart window, including the following steps: Antimony source and sulfur source are added to a mixed solvent composed of alkylamine and alkylthiol to obtain a precursor solution; The precursor solution was heated to obtain a liquid thermochromic system; The liquid thermochromic system is cooled and then poured into a sandwich structure formed by a first transparent substrate and a second transparent substrate; The sandwich structure is sealed to obtain the thermochromic liquid-filled smart window.

[0075] In one embodiment, the heating temperature is 80~120 °C, such as 100 °C; and the heating time is 5~30 min, such as 10 min.

[0076] In one embodiment, the sandwich structure is assembled using nano-residue-free adhesive, and the seal is achieved by edge sealing with UV-curable adhesive. This method is simple and suitable for the fabrication of large-area smart windows.

[0077] This embodiment also provides an application of thermochromic liquid-filled smart windows in building energy conservation. The application includes one or more of building exterior windows, glass curtain walls, skylights, and transparent building envelopes. This smart window can automatically adjust its solar radiation transmittance according to changes in ambient temperature, reducing cooling energy consumption in hot weather and mitigating heat loss in cold weather due to its low thermal conductivity, thereby achieving year-round energy savings.

[0078] The above technical solution will be further explained and illustrated through specific preparation examples below.

[0079] Example 1 A certain amount of antimony acetate Sb(Ac)3 and sulfur powder S were weighed and added to a mixed solvent composed of oleylamine and n-dodecyl mercaptan, wherein the volume ratio of oleylamine to n-dodecyl mercaptan was 1:1. The mixture was magnetically stirred at room temperature until a homogeneous, colorless, and transparent precursor solution was formed. The precursor solution was then heated to 100 °C and held at that temperature for 10 min, and then allowed to cool naturally to room temperature.

[0080] Throughout the heating process, a significant change in the appearance of the system can be observed: it is colorless and transparent at room temperature; as the temperature rises, the system gradually turns light yellow; after further heating, it turns orange-yellow and eventually exhibits a distinctly opaque coloring state; after cooling, it can return to a transparent and colorless state, indicating that the system has good reversible thermochromic behavior.

[0081] like Figure 2 The image shown is a photograph of the liquid thermochromic system of this invention during the heating process. The liquid thermochromic system of this invention exhibits continuous, distinct, and reversible color changes during heating, indicating that it can serve as a thermo-responsive dimming medium without the need for an external electric field. This embodiment demonstrates the feasibility of using the antimony source / sulfur source / alkylamine / alkylthiol system employed in this invention to construct a thermochromic functional liquid.

[0082] Example 2 The precursor solution was prepared according to the method in Example 1. Samples were taken at different target temperatures during the heating process and immediately quenched with an organic solvent to preserve the intermediate products formed at that temperature as much as possible. The quenched products were then analyzed by transmission electron microscopy (TEM), regional elemental distribution (EDX), and X-ray diffraction (XRD).

[0083] like Figure 3 The image shows TEM images of the quenching products of the liquid thermochromic system of this invention at different temperatures. At lower temperatures, the system mainly consists of small clusters or irregular particles; as the temperature increases, larger aggregates gradually appear in the sample, eventually forming more regular sheet-like or lamellar stacked structures. This indicates that the system of this invention undergoes a gradual evolution from precursor clusters to more ordered antimony sulfide nanostructures during heating.

[0084] like Figure 4 The figure shows the elemental distribution of the product of the liquid thermochromic system of this invention at 100 °C. In the plate-like structure region formed at high temperature, the distributions of Sb and S elements highly overlap, indicating that the obtained product is an antimony-sulfur compound rather than a simple mixture. This result further proves that the high-temperature coloring state corresponds to the formation of antimony sulfide nanostructures within the system.

[0085] like Figure 5The image shows the XRD patterns of the quenching products of the liquid thermochromic system of this invention at different temperatures. As the temperature increases, diffraction peaks corresponding to antimony sulfide crystals gradually appear and intensify, indicating that the system undergoes a transformation from an amorphous or low-crystallinity precursor state to crystalline antimony sulfide during heating. TEM, elemental distribution, and XRD results corroborate each other, demonstrating that the color change in the liquid thermochromic system of this invention originates from the heating-induced formation of antimony sulfide nanostructures.

[0086] Example 3 Different volume ratios of oleylamine / n-dodecyl mercaptan mixed solvents were prepared, such as 1:0, 2:1, 1:1, 1:2, and 0:1. The amounts of antimony and sulfur sources were kept consistent, and the precursor solutions were prepared and heated according to the method in Example 1. The appearance of the samples before heating, after heating, and after recooling was recorded, and the quenching products at 100 °C were characterized by physical examination and TEM.

[0087] like Figure 6 The images shown are photographs of alkylamine / alkylthiol mixtures at different volume ratios before heating, after heating, and after recooling. Different mixing ratios significantly affect the system's low-temperature transparency, high-temperature coloring intensity, and ability to recover transparency after cooling. At certain ratios, the system exhibits insufficient transparency at room temperature; at others, high-temperature coloring is inadequate; and at still others, complete recovery of transparency after cooling is difficult. Overall, a 1:1 volume ratio of oleylamine to n-dodecyl mercaptan demonstrates superior low-temperature transparency and reversible high-temperature coloring.

[0088] like Figure 7 The images shown are photographs and TEM images of the quenching products of alkylamine / alkylthiol mixtures at 100 °C with different volume ratios. The morphology of the products formed under different ratios varies significantly. Under some conditions, only small particles or random aggregates are formed, while at the preferred ratio, regular plate-like structures are more easily formed. These results indicate that alkylamines and alkylthiols not only act as solvents but also participate in the formation of antimony sulfide nanostructures through coordination, activation, and surface modulation.

[0089] This embodiment demonstrates that the ratio of binary solvents is one of the key parameters for controlling the performance of the liquid thermochromic system of the present invention.

[0090] Example 4 First, following the method in Example 2, the quenched product was obtained at 100 °C. Then, the product was added back into the oleylamine / n-dodecyl mercaptan mixed solvent and dispersed at room temperature by stirring or sonication. Its appearance was observed again, and the heating experiment was repeated.

[0091] like Figure 8The image shown is a photograph of the product after redispersing the high-temperature quenching product and restoring the thermochromic effect. The separated high-temperature product can be redissolved in a freshly prepared binary solvent, restoring a relatively homogeneous system, and upon reheating, it re-emerges as a transparent to colored change. This result demonstrates that the thermochromic effect of this invention is not an irreversible decomposition or a one-time reaction, but rather based on the reversible transformation between the antimony sulfide nanostructure and its soluble precursor state.

[0092] This embodiment further demonstrates that the liquid thermochromic system of the present invention is suitable for repeated thermal cycling and is an important foundation for building a long-term service smart window.

[0093] Example 5 Under the same solvent conditions, different antimony sources were selected, such as antimony acetate Sb(Ac)3, antimony trichloride SbCl3, and antimony trioxide Sb2O3; and different sulfur sources were selected, such as sulfur powder S, sodium sulfide Na2S, and thiourea CH4N2S. Each group of samples was prepared and heated according to the method in Example 1, and their appearance changes and thermochromic results were compared.

[0094] like Figure 9 The figure shows a comparison of the system under different antimony and sulfur sources. Different precursor combinations lead to significant differences in initial transparency, degree of coloration after heating, and recovery ability after cooling. The combination of antimony acetate and sulfur powder exhibits the best overall performance: the precursor solution has good transparency at room temperature, shows significant coloration after heating, and recovers transparency well after cooling. However, some other antimony or sulfur source combinations may result in turbidity of the system itself, insignificant color change, or poor reversibility.

[0095] This embodiment demonstrates that antimony acetate and sulfur powder are the preferred precursor combination for the liquid thermochromic system of the present invention.

[0096] Example 6 First, two transparent glass substrates, preferably quartz glass or architectural glass, are selected. A hollow sandwich structure is formed between the two substrates using transparent double-sided adhesive, with a pre-reserved injection port. Then, the liquid thermochromic system prepared in Example 1 and cooled to room temperature is injected into the sandwich structure using a syringe. After the liquid is completely filled, the edges of the device and the injection port are sealed using nano-residue-free adhesive and UV-curable adhesive to obtain a thermochromic liquid-filled smart window.

[0097] like Figure 10 The diagram shown illustrates the fabrication process of the thermochromic liquid-filled smart window of this invention. The fabrication process of the smart window of this invention is simple and clear, mainly including three steps: hollow sandwich assembly, functional liquid filling, and edge sealing. It is easy to operate and suitable for scale-up.

[0098] Under scale-up conditions, the amounts of precursor and solvent were increased proportionally to prepare a large-volume liquid thermochromic system, and its state at 20 °C and 80 °C was observed. Figure 11 The images shown are photographs of the mass-produced liquid thermochromic system at 20°C and 80°C. Under mass production conditions, the system maintains high transparency at 20°C and uniform coloration at 80°C, indicating that it retains good uniformity and reproducibility after scale-up preparation.

[0099] To evaluate its processing adaptability, the viscosity of the functional liquid of this invention was tested and compared with other common liquids. Figure 12 The figure shows a viscosity comparison of different liquids. The liquid thermochromic system of this invention has low viscosity, making it easy to inject, fill, and fill large areas, which is significantly superior to many high-viscosity gel-type dimming materials.

[0100] This embodiment demonstrates that the present invention not only possesses excellent functionality, but also has process advantages suitable for engineering preparation and large-scale application.

[0101] Example 7 A thermochromic liquid-filled smart window was prepared using the method described in Example 6. The appearance of the device was observed at 20 °C and 80 °C, and its transmittance spectrum was tested. Single-layer glass and ordinary laminated glass were selected as control samples.

[0102] like Figure 13 The image shows actual photographs of the smart window of this invention at 20 °C and 80 °C. The smart window of this invention exhibits high transparency at 20 °C, providing excellent visibility; at 80 °C, it shows noticeable coloration, demonstrating strong solar radiation blocking capabilities.

[0103] like Figure 14 The image shows the transmittance spectra of single-pane glass, laminated glass, and the smart window of this invention. The smart window of this invention maintains high visible light transmittance in its low-temperature transparent state, while exhibiting a more significant blocking effect on broadband solar radiation in its high-temperature tinted state. Compared to single-pane glass and ordinary laminated glass, the smart window of this invention can significantly improve shading and heat insulation capabilities under high-temperature conditions without significantly sacrificing low-temperature light transmission performance.

[0104] Example 8 The smart window of this invention was placed on a temperature-controlled platform, and its appearance was recorded at temperatures of 0 °C, 10 °C, 20 °C, 40 °C, 60 °C and 80 °C, respectively. Transmittance spectrum and haze changes were also tested.

[0105] like Figure 15The image shown is a photograph of the smart window in the temperature range of 0-80 °C. The sample exhibits high haze or semi-transparency in the 0-10 °C range; it regains high transparency near room temperature; and upon further heating, it gradually transforms into yellow, orange, and even deeper colors. This demonstrates that the smart window of this invention can exhibit different dimming characteristics in different temperature zones.

[0106] like Figure 16 The image shows the transmittance spectrum of the smart window in the range of 0–80 °C. As the temperature increases, especially in the higher temperature range, the transmittance of the sample decreases significantly, indicating that it has a temperature-triggered dynamic regulation capability for solar radiation.

[0107] like Figure 17 The figure shows the changes in haze and transmittance of the smart window within the temperature range of 0–80 °C. In the low-temperature region, the sample haze increases while the transmittance decreases, indicating that a scattering-type light-modulating effect mainly exists at this temperature. Near room temperature, the haze decreases and the transparency increases. In the higher-temperature region, the transmittance further decreases, mainly due to heat-induced coloration and enhanced absorption. This result demonstrates that the smart window of this invention can achieve a composite optical response over a wide temperature range.

[0108] Example 9 Liquid thermochromic systems with different concentrations of the active component Sb₂S₃ were prepared by varying the amounts of antimony acetate and sulfur powder while keeping the total volume of oleylamine and n-dodecyl mercaptan constant. Smart windows of corresponding concentrations were prepared, and the transmittance as a function of temperature was measured at a wavelength of 1000 nm.

[0109] like Figure 18 The figure shows the transmittance of samples with different concentrations at 1000 nm wavelength as a function of temperature. The onset temperature and modulation amplitude of the thermal response differ among samples with different concentrations. With increasing concentration, the samples exhibit a more significant decrease in transmittance at lower temperatures, indicating that increasing the concentration of the active component Sb₂S₃ helps to enhance the thermochromic intensity and lower the response temperature range. Considering both low-temperature transparency and high-temperature modulation capability, a concentration of approximately 6.56 mM shows superior performance.

[0110] Furthermore, a liquid system of preferred concentration was selected and filled into sandwich structures with thicknesses of 0.5 cm, 1.0 cm and 2.0 cm, respectively, and its transmittance spectra at 20 ℃ and 80 ℃ were tested.

[0111] like Figure 19 The figure shows the transmittance spectra of smart windows with different interlayer thicknesses at 20 ℃ and 80 ℃. The greater the interlayer thickness, the more significant the decrease in transmittance at high temperatures, indicating that a thicker liquid layer is beneficial for enhancing the solar radiation blocking effect; however, excessive thickness increases the amount of material used and the weight of the device. Therefore, considering the overall light transmittance, modulation capability, and practical application feasibility, a thickness of 1.0 cm is the preferred option.

[0112] Example 10 Common filling media such as the liquid thermochromic system of this invention, air, and water were selected, and their thermal conductivity and specific heat capacity were tested respectively. Figure 20 The figure shows the curves of thermal conductivity and specific heat capacity of different filling media as a function of temperature. The liquid thermochromic system of this invention has a low thermal conductivity, significantly lower than that of deionized water, indicating that it can reduce heat conduction through the filling layer of the window; at the same time, its specific heat capacity is higher than that of air, meaning that it has a certain thermal buffering capacity when the external temperature fluctuates. This feature enables the smart window of this invention to not only have a dimming function, but also to have heat insulation and a certain degree of heat preservation.

[0113] The smart window of this invention underwent multiple heating / cooling cycle tests, and its performance after long-term storage in an air environment was also examined. For example... Figure 21 The figure shows the cyclic stability of the smart window of this invention. The sample maintains a high transmittance adjustment capability even after multiple thermal cycles, indicating that the system of this invention has good long-term reliability.

[0114] Subsequently, different filled windows were placed under the same actual sunlight conditions, and their infrared thermal images and temperature rise curves were recorded. For example... Figure 22 The image shows infrared thermograms and temperature rise curves of different filled windows under actual sunlight. The intelligent window of this invention can rapidly heat up and trigger thermochromic changes under actual sunlight, thus creating an adaptive adjustment effect to solar radiation.

[0115] Furthermore, the smart window of this invention was installed at the opening of the model chamber, and its outdoor temperature control was compared with that of a control window. Figure 23 The figure shown is a graph illustrating the outdoor temperature control test results of the model chamber. Under outdoor solar irradiation conditions, the blackbody temperature and air temperature inside the model chamber equipped with the intelligent window of this invention are significantly lower than those of the control group, indicating that the intelligent window of this invention has excellent practical heat insulation and cooling effects.

[0116] Finally, a larger-sized thermochromic liquid-filled smart window was fabricated using a scale-up process, and its appearance uniformity was observed. Figure 24 The image shown is a photograph of a large-size thermochromic liquid-filled smart window. The large-size device exhibits good overall uniformity and consistency under both low and high temperature conditions, with no obvious delamination, localized failures, or color differences, indicating that this invention has the potential for large-area engineering applications.

[0117] Finally, it should be noted that the above embodiments are only for illustrating the present invention and not for limiting the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications, or equivalent substitutions of the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention and should be covered within the scope of the claims of the present invention.

Claims

1. A thermochromic liquid-filled smart window, characterized in that, It includes a first transparent substrate, a second transparent substrate, and a liquid thermochromic layer sandwiched between the first transparent substrate and the second transparent substrate; The liquid thermochromic layer is composed of a thermochromic system formed by an antimony source, a sulfur source, an alkylamine, and an alkyl thiol.

2. The thermochromic liquid-filled smart window according to claim 1, characterized in that, The antimony source is selected from one or more of antimony acetate, antimony trichloride, and antimony trioxide; Preferably, the antimony source is antimony acetate.

3. The thermochromic liquid-filled smart window according to claim 1, characterized in that, The sulfur source is selected from one or more of sulfur powder, sodium sulfide, and thiourea. Preferably, the sulfur source is sulfur powder.

4. The thermochromic liquid-filled smart window according to claim 1, characterized in that, The alkylamine is selected from one or more of oleylamine, butylamine, and octylamine; The alkyl thiol is one or more of n-dodecyl thiol, n-octyl thiol, or n-decyl thiol.

5. The thermochromic liquid-filled smart window according to claim 1, characterized in that, The volume ratio of the alkylamine to the alkylthiol is 3:1 to 1:3; Preferably, the volume ratio of the alkylamine to the alkylthiol is 1:

1.

6. The thermochromic liquid-filled smart window according to claim 1, characterized in that, During the heating process, antimony sulfide, an active component, is generated in the liquid thermochromic layer, and the concentration of the active component antimony sulfide is 0.87~8.75 mM. Preferably, the concentration of the active component antimony sulfide is 4.37~8.75 mM; more preferably, the concentration of the active component antimony sulfide is 6.56 mM.

7. The thermochromic liquid-filled smart window according to claim 1, characterized in that, The visible light transmittance T of the liquid thermochromic layer at 20 °C lum It is over 90%; Preferably, the visible light transmittance T of the liquid thermochromic layer at 20 °C is... lum The solar radiation modulation capability ΔT' of the liquid thermochromic layer at 80 °C is 95.0%. sol It is over 70%; Preferably, the liquid thermochromic layer has a solar radiation modulation capability ΔT' at 80 °C. sol It is 78.0%.

8. A method for preparing a thermochromic liquid-filled smart window as described in any one of claims 1-7, characterized in that, Includes the following steps: Antimony source and sulfur source are added to a mixed solvent composed of alkylamine and alkylthiol to obtain a precursor solution; The precursor solution was heated to obtain a liquid thermochromic system; The liquid thermochromic system is cooled and then poured into a sandwich structure formed by a first transparent substrate and a second transparent substrate; The sandwich structure is sealed to obtain the thermochromic liquid-filled smart window.

9. The method for preparing a thermochromic liquid-filled smart window according to claim 8, characterized in that, The heating temperature for the heat treatment is 80~120 °C; the heating time is 5~30 min. Preferably, the heating temperature is 100 °C; Preferably, the heating time is 10 minutes.

10. The application of a thermochromic liquid-filled smart window as described in any one of claims 1-7 in energy-saving control of building envelope.

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