Glass based on Bragg reflector for building energy-saving window and preparation method of glass
By depositing titanium dioxide and silica films on the transparent substrate of building energy-saving windows, building a Bragg reflector structure solves the shortcomings in thermal management performance of traditional windows, and achieving efficient thermal management and energy-saving effects, especially in hot climates, which can significantly reduce refrigeration energy consumption.
Patent Information
- Application Number
- CN202510231390.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-28
- Publication Date
- 2025-05-30
AI Technical Summary
Traditional windows lack thermal management performance, which is difficult to meet the energy-saving needs of modern buildings, especially in terms of how to easily and at low cost, combine Prague reflectors with building energy-saving windows to achieve efficient thermal management and energy-saving effects.
By depositing titanium dioxide films and silica films on transparent substrates, a Bragg reflector structure is constructed, and the solar radiation is selectively reflected to reduce refrigeration energy consumption. The method includes cleaning and hydrophilic treatment steps, deposition of the film using spin coating and electron beam evaporation techniques.
It realizes selective barriers to near-infrared light in the solar spectrum while maintaining high transmittance in the visible light area, which can achieve a cooling effect of close to 1℃ under hot climate conditions and reduces building refrigeration energy consumption.
Smart Images
Figure CN120058242A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of nano material assembly and functional device preparation, and in particular relates to a glass based on a Bragg reflector for energy-saving windows of buildings and a preparation method thereof. Background Art
[0002] Due to global warming, accelerated urbanization and the continuous improvement of people's living standards, space cooling energy consumption accounts for nearly one-fifth of the overall energy consumption of buildings, and the resulting energy and environmental problems are increasing day by day. If more active measures are not taken to improve the current situation, it is estimated that by 2050, global energy consumption for cooling will increase by more than three times, its share in building energy consumption will more than double, and the growth rate of carbon dioxide emissions related to cooling will also double. This trend highlights the urgency of developing efficient and energy-saving cooling technology. According to the British "Nature Communications" (Nature Communications, 2023, Vol. 14, pp. 3231-3239), every 1°C reduction in indoor temperature will reduce energy consumption by about 10%, which provides an important basis for the development of energy-saving technologies.
[0003] As one of the key components of building envelope, the thermal and optical properties of windows have an important impact on indoor temperature regulation and lighting functions, which in turn directly affects the overall energy consumption of the building. However, the design of traditional windows often focuses on the optimization of optical properties, but lacks in thermal management performance, making it difficult to meet the energy-saving needs of modern buildings.
[0004] As an optical device based on photonic crystal structure, Bragg reflector is a periodic structure formed by alternating thin films with different refractive index values. By adjusting the thickness and refractive index of the film, selective reflection of light of a specific wavelength can be achieved. Bragg reflectors have been widely used in lasers, optical communications, sensors, filtering and display technologies, but their application in energy-saving windows in buildings has rarely been reported.
[0005] Therefore, how to combine Bragg reflectors with building energy-saving windows through a simple and low-cost preparation method to achieve efficient thermal management and energy-saving effects is a technical problem that needs to be solved urgently. Summary of the invention
[0006] In view of this, the purpose of the present invention is to provide a glass based on a Bragg reflector for building energy-saving windows and a preparation method thereof. The glass prepared by the method can efficiently regulate solar radiation and reduce cooling energy consumption through the Bragg reflector structure, providing a new feasible solution for the design of building energy-saving windows.
[0007] In order to achieve the purpose, the present invention adopts the following technical scheme:
[0008] A glass based on a Bragg reflector for energy-saving building windows, comprising a transparent substrate, a titanium dioxide thin film deposited on one surface of the transparent substrate, and a silicon dioxide thin film deposited on the surface of the titanium dioxide thin film.
[0009] Preferably, the transparent substrate is a soda-lime glass sheet, which has a higher light transmittance compared to other substrates (such as silicon wafers, single-sided ITO conductive glass sheets, etc.).
[0010] Preferably, the soda-lime glass sheet needs to be cleaned and hydrophilized before depositing the thin film to improve the adhesion and uniformity of the thin film.
[0011] Preferably, the titanium dioxide thin film is deposited by spin-coating and assembling titanium dioxide nanoparticles, and the silicon dioxide thin film is deposited by electron beam evaporation technology.
[0012] More preferably, the particle size of the titanium dioxide nanoparticles is 4 - 15 nm. If the particle size is too large, it will affect the uniformity of the thin film.
[0013] Preferably, the thickness of the titanium dioxide thin film is 35 - 80 nm, and the thickness of the silicon dioxide thin film is 200 - 420 nm. The thicknesses of the two thin films will affect the wavelength range of sunlight reflected by the constructed Bragg reflector.
[0014] The present invention further discloses a preparation method of the glass based on the Bragg reflector, comprising the following steps:
[0015] 1) Add tetra-isopropyl titanate to deionized water, stir well to make it completely hydrolyzed to form a white precipitate; after separating and washing the precipitate, add tetramethylammonium hydroxide solution and stir until evenly dispersed, then put it into an oven for hydrothermal reaction. After the reaction is completed, centrifuge to remove large particle aggregates to obtain a colloidal solution of titanium dioxide nanoparticles;
[0016] 2) Ultrasonically clean the transparent substrate in acetone, absolute ethanol, and deionized water in sequence, and then perform hydrophilization treatment in a plasma cleaner;
[0017] 3) Add absolute ethanol to the colloidal solution of titanium dioxide nanoparticles prepared in step 1) to prepare a dispersion, spin-coat it on the transparent substrate treated in step 2), and dry it to obtain a titanium dioxide thin film;
[0018] 4) Continuously deposit a layer of silicon dioxide thin film on the titanium dioxide thin film formed in step 3) through an electron beam evaporation coater to obtain the glass based on the Bragg reflector.
[0019] Preferably, in step 1, the dosage ratio of tetra-isopropyl titanate, deionized water and tetramethylammonium hydroxide solution is 1.3 - 1.5 mL: 2.4 - 2.7 mL: 4.5 - 4.9 mL, and the mass concentration of the tetramethylammonium hydroxide solution is 0.55 - 0.65 mol / L.
[0020] Preferably, in step 1, the obtained white precipitate can be washed by centrifugal washing. The rotation speed of centrifugal washing is preferably 5000 - 6000 rpm, and the centrifugation time is preferably 5 - 10 minutes.
[0021] Preferably, in step 1, the temperature of the hydrothermal reaction is 110 - 130 °C and the time is 3 - 4 h.
[0022] Preferably, in step 2, the time of the hydrophilic treatment is 3 - 5 minutes and the gas used is air.
[0023] Preferably, in step 3, the volume ratio of the colloidal solution of titanium dioxide nanoparticles to absolute ethanol is 1: 0 - 2. The rotation speed is 2000 - 8000 rpm and the spin coating time is 30 - 60 s. The drying temperature is 240 - 260 °C and the drying time is 0.5 - 1 h.
[0024] Preferably, in step 4, the deposition rate of the silicon dioxide film is The electron beam output power is 20 - 30%.
[0025] Compared with the prior art, the beneficial effects of the present invention are reflected in:
[0026] The present invention provides a glass based on a Bragg reflector and its preparation method. Its structure includes a transparent substrate, a titanium dioxide thin film layer, and a silicon dioxide thin film layer. The glass of the present invention can be used for energy-saving building windows. Compared with the existing building windows, the present invention selects two common and easily available materials, titanium dioxide and silicon dioxide. Their synthesis methods are mature, with excellent optical properties, good chemical stability, non-toxicity and low cost. And a double-layer composite film type Bragg reflector can be efficiently constructed through the simple spin coating method and the mature electron beam evaporation technology. The Bragg reflector constructed by the present invention can selectively block the near-infrared light in the solar spectrum while maintaining a high transmittance in the visible light region, and is applicable to indoor cooling under hot climate conditions. Experimental results show that for the double-layer film type Bragg reflector prepared by sequentially depositing a titanium dioxide thin film with a thickness of about 80 nm and a silicon dioxide thin film with a thickness of about 265 nm on a soda-lime glass sheet substrate, after 30 minutes of direct sunlight under 1 sunlight intensity, a temperature reduction effect of nearly 1 °C can be achieved, and its transmittance at 555 nm is as high as 94%, providing a feasible technical solution for reducing the building cooling energy consumption under hot climate conditions. Description of the Drawings
[0027] Figure 1 It is the TEM image of the titanium dioxide nanoparticles synthesized in Example 1 of the present invention.
[0028] Figure 2 It is the DLS image of the titanium dioxide nanoparticles synthesized in Example 1 of the present invention.
[0029] Figure 3 It is the cross-sectional SEM image of the titanium dioxide thin film layer prepared in Example 1 of the present invention.
[0030] Figure 4 It is the cross-sectional SEM image of the Bragg reflector structure constructed in Example 1 of the present invention.
[0031] Figure 5 It is the reflection spectrum image of the Bragg reflector structure constructed in Example 1 of the present invention.
[0032] Figure 6 It is the transmission spectrum image of the Bragg reflector structure constructed in Example 1 of the present invention.
[0033] Figure 7 It is the simulated indoor real-time temperature change curve graph of the ordinary soda-lime glass sheet and the constructed Bragg reflector structure in Example 1 of the present invention ( Figure 7 (a) in) and the final stable temperature comparison graph ( Figure 7 (b) in).
[0034] Figure 8 It is the reflection spectrum image of the Bragg reflector structure constructed based on silicon dioxide thin films with different thicknesses in Example 2 of the present invention.
[0035] Figure 9 It is the transmission spectrum image of the Bragg reflector structure constructed based on silicon dioxide thin films with different thicknesses in Example 2 of the present invention.
[0036] Figure 10 It is the reflection spectrum image of the Bragg reflector structure constructed based on titanium dioxide thin films with different thicknesses in Example 3 of the present invention.
[0037] Figure 11 It is the transmission spectrum image of the Bragg reflector structure constructed based on titanium dioxide thin films with different thicknesses in Example 3 of the present invention.
[0038] Figure 12 It is the simulated indoor real-time temperature change curve graph of the ordinary soda-lime glass sheet and the Bragg reflector structure constructed based on titanium dioxide thin films with different thicknesses in Example 3 of the present invention ( Figure 12 (a) in) and the final stable temperature comparison graph ( Figure 12 (b) in). Detailed implementation manners
[0039] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
[0040] The reagents used in the following examples are all commercially available.
[0041] Example 1
[0042] The glass based on the Bragg reflector is prepared according to the following steps in this example:
[0043] (1) First, measure 1.42 mL of titanium tetraisopropoxide and slowly add it dropwise into 2.56 mL of deionized water. Stir well for 1 hour with a magnetic stirrer until hydrolysis is complete. The obtained white precipitate is centrifugally washed with deionized water at a speed of 5000 rpm for 5 minutes, and the operation is repeated 3 times. Then, measure 1.18 mL of aqueous tetramethylammonium hydroxide solution (mass concentration of 25%) and 3.5 mL of deionized water to prepare a 0.6 mol / L tetramethylammonium hydroxide solution, and add it to the washed fresh precipitate, and stir evenly for 30 minutes. After the white liquid is evenly dispersed, transfer it to a 10 mL polytetrafluoroethylene reaction kettle liner and hydrothermally synthesize it at 120 °C for 3 hours. After the reaction is completed, the obtained colorless and transparent suspension is further centrifuged at 12000 rpm for 10 minutes to remove large particle aggregates, and the obtained supernatant is a colloidal solution of titanium dioxide nanoparticles.
[0044] Figure 1 and Figure 2 are the TEM image and DLS image of the synthesized titanium dioxide nanoparticles. It can be seen from Figure 1 that the titanium dioxide nanoparticles are spherical in morphology, with an average particle size of about 7 - 8 nm, and the size distribution is relatively uniform and the monodispersity is good; Figure 2 The DLS result of
[0045] (2) The soda-lime glass substrate with a light transmittance ≥ 90% and a size of 30 * 30 * 11 mm is ultrasonically cleaned in acetone, absolute ethanol, and deionized water for 10 minutes respectively, dried at room temperature, and then subjected to hydrophilic treatment for 5 minutes by a plasma cleaner.
[0046] (3) Add an equal volume of absolute ethanol to the colloidal solution of titanium dioxide nanoparticles prepared in step (1), and ultrasonically disperse for 10 minutes to obtain a dispersion. Take 100 μL of the dispersion and drop it onto the transparent substrate treated in step (2). After the liquid completely covers the substrate, spin-coat at a rotation speed of 2000 rpm for 60 seconds with an acceleration of 9000 rpm / s. Let the spin-coated film stand at room temperature to volatilize for 30 minutes, then put it into an oven at 250 °C for heat treatment for 30 minutes, and cool it to room temperature to obtain the titanium dioxide film.
[0047] Figure 3 Figure 4 is the cross-sectional SEM image of the prepared titanium dioxide thin film layer. It can be seen from the figure that the film is composed of particle accumulation and the film thickness is about 80 nm.
[0048] (4) Use an electron beam evaporation coating instrument to continue depositing a film on the titanium dioxide film. The target material in the target crucible is silicon dioxide particles, and the deposition rate is The electron beam output power is controlled at 20 - 30%.
[0049] Figure 4 Figure 13 is the SEM image of the Bragg reflector structure constructed in this embodiment. It can be seen from the figure that there are two layers of films deposited on the glass substrate. The lower, brighter one is the titanium dioxide film with a thickness of about 80 nm, and the upper, darker one is the silicon dioxide film with a thickness of about 265 nm.
[0050] Figure 5 and Figure 6 Figure 19 and Figure 20 are respectively the reflection spectrum and transmission spectrum of the Bragg reflector structure constructed in this embodiment, and their comparison with the silicon dioxide and titanium dioxide films deposited separately on the glass substrate. It can be seen from Figure 5 that there is an obvious reflection peak in the Bragg reflector structure constructed between 401 - 618 nm, which corresponds to the transmission peak between 403 - 616 nm in Figure 6 . There is also a wide and strong transmission peak in Figure 6 near the near-infrared light region, that is, between 626 - 1270 nm. Comparing the spectra of the silicon dioxide and titanium dioxide films deposited separately, the optical properties of the Bragg reflector are not simply linearly superimposed by the optical properties of the two layers of films, but are caused by the structure of the double-layer composite film.
[0051] To verify the thermal management performance of the constructed Bragg reflector structure, a simulated indoor temperature control test was carried out. The prepared glass based on the Bragg reflector was fixed on a model house with a 2.5 cm × 2.5 cm window. Except for the test window, the interior of the model house was wrapped with aluminum foil to reduce the temperature influence caused by thermal radiation. A 3.0 cm × 3.0 cm × 1.0 cm black anodized aluminum cuboid was placed as a blackbody absorber in the center of the model house, and a thermocouple was firmly adhered to the blackbody absorber. Simulating sunlight irradiation with a xenon lamp, it was irradiated directly on the window for 30 min at an intensity of 1 sun (100 mW / cm 2 ), and the thermocouple was used to record the real-time temperature change of the blackbody absorber.
[0052] Figure 7 This is the graph of the simulated indoor real-time temperature change curve of the ordinary soda-lime glass sheet and the constructed Bragg reflector structure in this embodiment ( Figure 7 (a) in), and the comparison graph of the final stable temperature ( Figure 7 (b) in). It can be seen from the figure that the temperature of the ordinary soda-lime glass sheet gradually rises from room temperature to 40.3 °C, and the final temperature of the constructed Bragg reflector structure stabilizes at 39.4 °C, achieving a temperature reduction effect of nearly 1 °C.
[0053] Example 2
[0054] In this example, the glass based on the Bragg reflector was prepared by the same method as in Example 1, except that the thickness of the silicon dioxide thin film in step (4) was adjusted to 201 nm, 312 nm, and 392 nm, and the constructed Bragg reflector structures were respectively denoted as Bragg Reflector 1, 2, and 3.
[0055] Figure 8 And Figure 9 are the reflection spectrum and transmission spectrum diagrams of the Bragg reflector structures constructed based on silicon dioxide thin films with different thicknesses. It can be seen from the figure that the number of transmission peaks increases with the increase in the thickness of the silicon dioxide film layer, and it is speculated that the transmission spectrum is gradually redshifted. Correspondingly, the reflection spectrum also redshifts with the increase in the silicon dioxide film thickness. However, the reflection peaks in the near-infrared light region are masked by the reflection spectrum of the substrate due to insufficient peak intensity. Considering that the constructed Bragg reflector structure needs to simultaneously meet the requirements of blocking near-infrared light in the solar spectrum and maintaining high transmittance in the visible light region, the Bragg reflector with a silicon dioxide thin film thickness of 250 - 330 nm is a more ideal choice.
[0056] Example 3
[0057] This embodiment prepares the glass based on the Bragg reflector in the same method as in Embodiment 1, with the only difference being that the thickness of the titanium dioxide thin film in step (3) is adjusted to 80 nm, 61 nm, and 43 nm, and the constructed Bragg reflector structures are respectively denoted as Bragg Reflector 4, 5, and 6.
[0058] Figure 10 and Figure 11 are the reflection spectra and transmission spectra of the Bragg reflector structures constructed based on titanium dioxide thin films with different thicknesses. It can be seen from the figure that all three structures have a reflection peak in the visible light region, and the corresponding transmission peak can also be found in the transmission spectrum. Another transmission peak is located near the near-infrared light region. In addition, both the reflection spectrum and the transmission spectrum gradually shift to the blue as the thickness of the titanium dioxide thin film decreases.
[0059] Figure 12 are the simulated indoor real-time temperature change curve graphs ([[(a) in]] Figure 12 and the final stable temperature comparison graph ([[(b) in]] Figure 12 ) of the ordinary soda-lime glass sheet and the Bragg reflector structures constructed based on titanium dioxide thin films with different thicknesses. It can be seen from the figure that the temperature of the ordinary soda-lime glass sheet gradually rises from room temperature to 40.3 °C, and the final temperatures of the three constructed Bragg reflector structures are stable at 39.4 °C, 39.6 °C, and 39.5 °C.
[0060] The above are only exemplary embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.
Claims
1. A glass based on a Bragg reflector for energy-saving windows in buildings, characterized in that: The invention comprises a transparent substrate, a titanium dioxide film deposited on one side of the transparent substrate, and a silicon dioxide film deposited on the surface of the titanium dioxide film.
2. The glass based on the Bragg reflector according to claim 1, characterized in that The transparent substrate is a soda-lime glass sheet.
3. The Bragg reflector-based glass according to claim 1, characterized in that The titanium dioxide film is deposited by titanium dioxide nanoparticles through a spin coating assembly technology, and the silicon dioxide film is deposited by an electron beam evaporation technology.
4. The glass based on the Bragg reflector according to claim 3, characterized in that The particle size of the titanium dioxide nanoparticles is between 4 and 15 nm.
5. The Bragg reflector-based glass according to claim 1, characterized in that The thickness of the titanium dioxide film is 35-80 nm, and the thickness of the silicon dioxide film is 200-420 nm.
6. A method for preparing a glass based on a Bragg reflector according to any one of claims 1 to 5, characterized in that: The following steps are involved: 1) adding tetraisopropyl titanate into deionized water and stirring it thoroughly to completely hydrolyze it to generate a precipitate; after separating and washing the precipitate, adding tetramethylammonium hydroxide solution dropwise thereto and stirring until it is evenly dispersed, and then placing it in an oven for hydrothermal reaction; after the reaction is completed, centrifuging to remove large particle aggregates to obtain a colloidal solution of titanium dioxide nanoparticles; 2) placing the transparent substrate in acetone, anhydrous ethanol, and deionized water for ultrasonic cleaning in sequence, and then placing it in a plasma cleaning machine for hydrophilic treatment; 3) adding anhydrous ethanol to the colloidal solution of titanium dioxide nanoparticles prepared in step 1) to prepare a dispersion, spin coating the dispersion on the transparent substrate treated in step 2), and drying the dispersion to obtain a titanium dioxide film; 4) A layer of silicon dioxide film is further deposited on the titanium dioxide film formed in step 3) by an electron beam evaporation coating apparatus to obtain a glass based on a Bragg reflector.
7. The preparation method according to claim 6, characterized in that: In step 1: the usage ratio of tetraisopropyl titanate, deionized water and tetramethylammonium hydroxide solution is 1.3-1.5 mL: 2.4-2.7 mL: 4.5-4.9 mL, and the mass concentration of the tetramethylammonium hydroxide solution is 0.55-0.65 mol / L.
8. The preparation method according to claim 6, characterized in that: In step 1, the temperature of the hydrothermal reaction is 110-130° C. and the time is 3-4 hours.
9. The preparation method according to claim 6, characterized in that: In step 3, the volume ratio of the colloidal solution of titanium dioxide nanoparticles to anhydrous ethanol is 1:0-2, the rotation speed is 2000-8000 rpm, the spin coating time is 30-60 s, the drying temperature is 240-260° C., and the drying time is 0.5-1 h.
10. The preparation method according to claim 6, characterized in that: In step 4, the deposition rate of the silicon dioxide film is The electron beam output power is 20-30%.