A Kirigami structure VO2 smart window with active angle control, its installation method and application

Abstract

The present invention discloses a Kirigami structure VO2 smart window with active angle control, as well as a method for setting up and application thereof. The smart window comprises a window unit, a movable unit, a control unit, and a sensing unit. The window unit comprises a Kirigami structure VO2 film, an upper fixed plate, and a lower adjustment plate, wherein the upper fixed plate and the lower adjustment plate are respectively mounted at both ends of the Kirigami structure VO2 film. The sensing unit is disposed on the side of the Kirigami structure VO2 film close to the window. The movable unit is connected to the lower adjustment plate. The control unit is connected to the movable unit and the sensing unit and is configured to move the Kirigami structure VO2 film according to the obtained sunlight angle. The smart window of the present invention utilizes the synergistic effect of the thermo-induced phase change of VO2 and the Kirigami structure, resulting in high visible light transmittance and a large sunlight modulation range. The smart window can also move and change its own angle as the sunlight angle changes, so that the film is always perpendicular to the sunlight, thereby increasing the effective utilization area.

Description

Technical Field

[0001] The present invention relates to the technical field of thermochromic smart windows, and in particular to a Kirigami structure VO2 smart window with active angle control, and a construction method and application thereof. Background Art

[0002] Vanadium dioxide (VO2) has a molecular weight of 82.94 and undergoes a reversible phase transition from a low-temperature monoclinic phase (M) to a high-temperature tetragonal rutile phase (R) near the phase transition temperature. Its properties also change suddenly, manifesting as a thermochromic phenomenon. Inorganic thermochromic materials have relatively high phase transition temperatures, with complexes, iodides, and other materials having thermochromic temperatures mostly above 100°C. Compared with these materials, the thermochromic temperature of VO2 is closer to room temperature, and the visible light transmittance and reflectivity of VO2 remain almost unchanged before and after the phase transition, but the transmittance and reflectivity of infrared light undergo a sudden change. This feature allows the VO2 material to actively regulate the transmittance of infrared light as the temperature changes, reducing heat entry, while maintaining the color and visible light transmittance. This gives it an irreplaceable advantage in the production of smart windows.

[0003] However, VO2 suffers from issues such as high phase transition temperature, narrow solar modulation range, and low visible light transmittance, which limit its application in smart windows. Furthermore, the incident angle of sunlight on windows varies with time and season, and the actual effective area of ​​the smart window also changes. Evaluating the energy efficiency of smart windows solely based on the film's modulation performance under direct sunlight is not a realistic criterion for actual application.

[0004] Therefore, it is necessary to design a VO2 smart window that can be adjusted according to the incident angle of sunlight and has a wide range of sunlight modulation. Summary of the Invention

[0005] The present invention uses tungsten-doped vanadium dioxide powder coated with a polymer dispersant as the functional raw material and polyurethane acrylate as the film-forming material, and utilizes 3D light-curing printing to prepare a VO2 thermochromic film with a kirigami structure. Assisted by light tracking equipment and a motor, a VO2 thermochromic smart window is produced that can change its own angle as the angle of sunlight changes.

[0006] In order to achieve the above objectives, the present invention provides a Kirigami structure VO2 smart window with active angle control, including a window unit, a moving unit, a control unit, and a sensing unit;

[0007] The window unit includes a Kirigami structure VO2 film, an upper fixing plate, and a lower adjusting plate. The upper fixing plate and the lower adjusting plate are respectively installed at both ends of the Kirigami structure VO2 film. The upper fixing plate is used to fix the Kirigami structure VO2 film on the window.

[0008] The sensing unit is arranged on the side of the Kirigami structure VO2 film close to the window, and is used to track the angle of sunlight;

[0009] The moving unit is connected to the lower adjustment plate and is used to move the Kirigami structure VO2 film;

[0010] The control unit is connected to the moving unit and the sensing unit, and is used to move the Kirigami structure VO2 film according to the obtained sunlight angle, so that the Kirigami structure VO2 film is perpendicular to the sunlight.

[0011] Furthermore, the method for preparing the Kirigami structure VO2 thin film includes:

[0012] S1, mixing a film-forming agent and a dispersant-coated tungsten-doped VO2 to obtain a suspension;

[0013] S2. Perform 3D photocuring printing to obtain a 50-800 μm Kirigami structure VO2 film.

[0014] Furthermore, the film-forming agent is formed by mixing a polyurethane acrylate prepolymer, a diluent and a photoinitiator;

[0015] The mass ratio of polyurethane acrylate prepolymer, diluent and photoinitiator is 1:0.5-1.5:0.01-0.05;

[0016] The diluent is an acrylate type diluent;

[0017] The photoinitiator is at least one of TPO, photoinitiator 184, and photoinitiator 1173.

[0018] Furthermore, the dispersant-coated tungsten-doped VO2 is obtained by mixing tungsten-doped VO2 and a dispersant and then wet-milling the mixture. The mass ratio of the tungsten-doped VO2 to the dispersant is 1:0.5-1.5.

[0019] Furthermore, the dispersant includes at least one of polyvinyl pyrrolidone, triethylhexyl phosphate, sodium lauryl sulfate, methyl amyl alcohol, cellulose derivatives, polyacrylamide, guar gum, and fatty acid polyethylene glycol esters;

[0020] The particle size of the tungsten-doped VO2 is 20-200 nm, and the tungsten doping amount is 1-5%.

[0021] Furthermore, the 3D light-curing printing includes setting a layer thickness of 0.05 to 0.2 mm and a light-curing time of 3.0 to 12.0 s;

[0022] It also includes setting the ratio of the distance d between pores in the same row, the pore length l and the spacing h between adjacent rows;

[0023] Furthermore, the ratio of the pore distance d in the same row, the pore length l and the spacing h between adjacent rows is 1:8-10:0.5-2.

[0024] Furthermore, the moving unit is a servo motor;

[0025] The control unit is a single chip microcomputer;

[0026] The sensing unit is a light sensing sensor.

[0027] Preferably, two light sensors are mounted on the upper and lower ends of the kirigami VO2 film. If the two light sensors capture different light intensities, they transmit a signal to a single-chip microcontroller (MCU), which controls the rotation of a lower adjustment plate, thereby controlling the movement of the kirigami VO2 film, until the light intensities on both sensors are the same, at which point the kirigami VO2 film is perpendicular to the sunlight. Specifically, the two light sensors each capture light energy. If the sunlight is not perpendicular to the smart window, the upper and lower light sensors will read different values, which are transmitted to the MCU. The difference in these values ​​can be used to estimate the direction of the sun relative to the film. If the sunlight is perpendicular to the smart window, the upper and lower sensors will read the same value.

[0028] Furthermore, two light sensors and a servo motor are connected to the single chip microcomputer at the same time.

[0029] The present invention also provides a method for setting up the above-mentioned Kirigami structure VO2 smart window with active angle control, comprising:

[0030] A light sensor is installed at the upper and lower ends of the Kirigami structure VO2 film;

[0031] Install the upper fixing plate and the lower adjustment plate on the upper and lower ends of the Kirigami structure VO2 film, and then fix the upper fixing plate to the window;

[0032] Connect the servo motor to the lower adjustment board, and connect the microcontroller to the servo motor and light sensor.

[0033] The present invention also provides the application of the above-mentioned Kirigami structure VO2 smart window with active angle control in adjusting indoor light transmittance.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The smart window of the present invention utilizes the synergistic effect of the thermoinduced phase change of VO2 and the Kirigami structure. It has high visible light transmittance and a large sunlight modulation range. It can also move and change its own angle as the angle of sunlight changes, so that the film is always perpendicular to the sunlight, thereby increasing the effective utilization area. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 Shown are infrared spectra of Sample 1 and Sample 2 of the present invention;

[0038] Figure 2 Shown are shear rheology diagrams of Samples 3 and 4 of the present invention;

[0039] Figure 3 shows the XRD patterns of sample 5 of the present invention and tungsten-doped VO2;

[0040] Figure 4 The projection electron microscope image of tungsten-doped VO2 of the present invention is shown, wherein: Figure 4 (a) Scale bar: 100 nm. Figure 4 (b) Scale bar 50 nm;

[0041] Figure 5 Shown is a transmission electron microscope image of sample 5 of the present invention;

[0042] Figure 6 The water contact angle results of samples 6 to 9 of the present invention are shown;

[0043] Figure 7 The transmittance of samples 6 to 9 of the present invention at different wavelengths of light is shown;

[0044] Figure 8 A schematic diagram of the Kirigami structure in Example 1 of the present invention is shown;

[0045] Figure 9 A schematic diagram of a Kirigami structure VO2 smart window with active angle control according to the present invention is shown;

[0046] Figure 10 The actual working diagram of the Kirigami structure VO2 smart window with active angle control of the present invention is shown;

[0047] Figure 11The transmittance of the Kirigami structure VO2 film in Example 1 of the present invention under different wavelengths of light is shown;

[0048] Figure 12 The relationship between the rotation angle of the Kirigami structure VO2 film and the stretching ratio of Examples 1 to 3 of the present invention is shown;

[0049] Figure 13 The relationship between the rotation angle of the Kirigami structure VO2 film and the stretching ratio of Example 1, Example 4 and Example 5 of the present invention is shown;

[0050] Description of reference numerals:

[0051] 1. Upper fixed plate; 2. Kirigami structure VO2 film; 3. Lower adjustment plate; 4. Light sensor; 5. Microcontroller; 6. Servo motor. DETAILED DESCRIPTION

[0052] The tungsten-doped VO2 used in the present invention is purchased directly and has an average particle size of 50 to 100 nm and a tungsten doping amount of 2%.

[0053] The preparation method of the polyurethane acrylate prepolymer used in the present invention is as follows:

[0054] Add 0.01 mol of polybutylene glycol 1000 to a three-necked flask and a magnet. Place 0.03 mol of toluene diisocyanate in a constant-pressure funnel and cool to 75°C. Remove the right oil pump and plug it with a rubber stopper. Place the constant-pressure funnel on the center neck. Install a spherical condenser and a nitrogen-filled balloon on the left neck to form a nitrogen-protected reflux system. Unscrew the constant-pressure separatory funnel and add toluene diisocyanate dropwise. Stir and react for 4 hours. Then, lower the oil pan temperature to 65°C. Weigh 0.01 mol of 1,4-butanediol into a syringe and add it to the three-necked flask through the right rubber stopper. Allow to react for 1 hour. Adjust the temperature of the oil pan to 75°C, weigh 0.02 mol of hydroxyethyl acrylate, add it to the constant pressure separatory funnel placed in the middle hole of the three-necked flask, then unscrew the constant pressure separatory funnel, add hydroxyethyl acrylate dropwise into the three-necked flask, and then add a drop of dibutyltin dilaurate solution. Continue stirring and reacting for 6 hours to obtain a polyurethane acrylate prepolymer, which is recorded as sample 1.

[0055] Preparation of film-forming reagent: Take 5.00 g of sample 1, add 3.00 g of 1,6-hexanediol diacrylate, 1.00 g of trimethylolpropane triacrylate, and 1.00 g of tripropylene glycol diacrylate, and finally add 3.0% of the mass of sample 1 as photoinitiator TPO (diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide), magnetically stir for 4 hours, low-temperature ultrasonic oscillation for 0.5 hours, and then stir for 8 hours to ensure that the mixture is evenly mixed to obtain a film-forming reagent, recorded as sample 3.

[0056] Similarly, polybutylene glycol 1000 was replaced by polybutylene glycol 2000, and the obtained polyurethane acrylate prepolymer and film-forming agent were recorded as sample 2 and sample 4, respectively.

[0057] The infrared spectra of sample 1 and sample 2 are shown in Figure 2. Figure 1 As shown, it can be seen that the characteristic peak of the reaction monomer disappears, and the polyurethane acrylate prepolymer is successfully prepared.

[0058] Shear rheology of film-forming agents prepared from polyurethane acrylate prepolymers prepared from polybutylene glycol with different polymerization degrees Figure 2 As shown, it can be seen that under the same conditions, the viscosity of the film-forming agent prepared with the polyurethane acrylate prepolymer prepared with polybutylene glycol 2000 is higher.

[0059] Of course, in the present invention, polyurethane acrylate prepolymers with similar performance can also be directly purchased and used.

[0060] The present invention discloses a method for preparing dispersant-coated tungsten-doped VO2. The method includes adding tungsten-doped VO2 and a dispersant to a solvent, stirring and mixing under ultrasound, and then ball-milling. The resulting liquid is collected and centrifuged to remove insoluble matter. The resulting liquid is then subjected to rotary evaporation and dried, milled, to obtain the dispersant-coated tungsten-doped VO2. The dispersant includes at least one of polyvinyl pyrrolidone, triethylhexyl phosphate, sodium lauryl sulfate, methyl amyl alcohol, a cellulose derivative, polyacrylamide, guar gum, and polyethylene glycol esters of fatty acids.

[0061] In a preferred embodiment of the present invention, the dispersant-coated tungsten-doped VO2 is polyvinyl pyrrolidone-coated tungsten-doped VO2, and its preparation method is: add 0.50 g of tungsten-doped VO2 and 0.50 g of PVP to 20 mL of ethanol, stir and ultrasonically mix, and then ball mill for 4 hours, take the ball milling liquid and centrifuge at 8000 rpm for 5 minutes to collect insoluble matter, and then obtain polyvinyl pyrrolidone-coated tungsten-doped VO2 through rotary evaporation and dry grinding, which is sample 5.

[0062] The XRD results of tungsten-doped VO2 and sample 5 are shown in the figure. It can be seen that a new diffraction peak appears at 23°, which indicates that polyvinyl pyrrolidone is modified on the surface of tungsten-doped VO2.

[0063] Figure 4 (a) and Figure 4 (b) shows transmission electron microscope images of tungsten-doped VO2 at different magnifications, from which it can be seen that the boundaries around tungsten-doped VO2 are clear. Figure 5 The transmission electron microscope image of sample 5 is shown, from which it can be seen that there is a transparent layer on the surface of tungsten-doped VO2, and it can be seen that polyvinyl pyrrolidone is successfully coated on the surface of tungsten-doped VO2 by wet ball milling.

[0064] 0.05g, 0.10g, 0.15g, and 0.20g of polyvinylpyrrolidone-coated tungsten-doped VO2 were added to 20g of sample 4, ultrasonicated for 0.5h, and stirred for 4h to obtain a mixed liquid, which was then 3D photocuring printed to obtain a VO2 film with a thickness of 200μm, which were recorded as sample 6, sample 7, sample 8, and sample 9 respectively. The water contact angles of samples 6 to 9 were tested and the results are shown as follows: Figure 6 As shown in Figure 2, it can be seen that as the VO2 content increases, the water contact angle of the VO2 film decreases, and the lower the water contact angle, the better the water wettability of the surface.

[0065] Samples 6-9 had a yellow-brown appearance. Further spectrophotometric testing of the colors of these samples was performed. The results are shown in Table 1, which includes the L* (brightness), a* (red-green), and b* (yellow-blue) values. As the content of tungsten-doped VO2 in the polyvinylpyrrolidone-coated films increases, the brightness decreases and the b* value increases.

[0066] Table 1 Color of samples 6 to 9

[0067]

[0068] The transmittance of samples 6 to 9 at different wavelengths was tested at 20°C and 90°C. The results are as follows: Figure 7 As shown, the solid line is 20°C and the dotted line is 90°C. Table 2 shows the solar light modulation efficiency results of samples 6 to 9, where T lum is the visible light transmittance, T sol is the sunlight transmittance, ΔT sol is the sunlight modulation efficiency. lum The higher the value, the higher the visible light transmittance of the film. sol The higher the value, the larger the film's modulation range for sunlight, and the better the film's modulation effect.

[0069] Table 2 Solar light modulation efficiency of samples 6 to 9

[0070]

[0071] From the results in Table 2, it can be seen that the higher the content of VO2 doped with polyvinylpyrrolidone-coated tungsten, the larger the modulation range of sunlight, but the lower the transmittance of visible light and sunlight.

[0072] The following will be combined with the specific embodiments of the present invention and the accompanying drawings to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The film-forming reagent used in the embodiment is sample 4, and the preparation method of the film-forming reagent and polyvinyl pyrrolidone-coated tungsten-doped VO2 will not be repeated.

[0073] Example 1

[0074] A method for constructing a Kirigami-structured VO2 smart window with active angle control, comprising the following steps:

[0075] Step 1: Mixing a film-forming reagent and polyvinylpyrrolidone-coated tungsten-doped VO2 (accounting for 1% of the film-forming reagent) to obtain a suspension;

[0076] Step 2: Set the printing layer thickness to 0.2mm and the light curing time to 10.5s. The Kirigami structure is as follows: Figure 8 As shown, the ratio of the pore distance d in the same row, the pore length l and the spacing h between adjacent rows is set to 1:9:1, and the suspension is subjected to 3D photocuring printing to obtain a 200 μm Kirigami structure VO2 film 2;

[0077] Step 3: Install two light sensors 4 on the Kirigami structure VO2 film 2, one above and one below; install the upper fixing plate 1 and the lower adjustment plate 3 on the upper and lower ends of the Kirigami structure VO2 film 2, and then fix the upper fixing plate 1 to the window; connect the servo motor 6 to the lower adjustment plate 3, and connect the single chip computer 5 to the servo motor 6 and the light sensor 4 to obtain the following: Figure 9 and Figure 10 The Kirigami structure VO2 smart window with dynamic angle control is shown.

[0078] The operating principle of the Kirigami structure VO2 smart window with active angle control is as follows:

[0079] The microcontroller contains programming code, which consists of two main parts: the setup() function and the loop() function. The setup() function only needs to be executed once, when the microcontroller is first connected to other components. It tests and initializes variables, sets pin modes, and configures the light sensor or servo motor. The loop() function, executed after the setup() function completes, controls the operation of each component, reading relevant data from the light sensor or servo motor, performing calculations and judgments, and then sending command outputs based on the results to the corresponding actuators. When the difference in the electrical signals emitted by the upper and lower light sensors is not equal to zero, the control system microcontroller applies voltage to the servo motor, driving it to rotate and move the Kirigami structure VO2 film, causing the light sensor to change its angle, resulting in a corresponding change in light intensity. The changed light signal is then converted into an electrical signal and transmitted to the servo motor until the difference between the upper and lower light sensors is zero, at which point the film is perpendicular to the sunlight.

[0080] After the Kirigami structure VO2 film was stretched by 0%, 20%, 40%, and 60%, the transmittance of the Kirigami structure VO2 film with different stretching degrees at 20℃ and 90℃ under different wavelengths of light was tested. The results are as follows: Figure 11 As shown, the solid line is 20° C. and the dotted line is 90° C. Table 3 shows the solar light modulation efficiency results of Kirigami structured VO2 films with different stretching degrees.

[0081] Table 3 Solar light modulation efficiency of Kirigami-structured VO2 films with different stretching degrees

[0082]

[0083] As can be seen from Table 3, as the stretching rate increases, the film's visible light transmittance gradually increases, while its solar light modulation capability gradually decreases. When the film is stretched from unstretched to 60%, the film's visible light transmittance increases from 53.56% to 76.92%, while its solar light modulation capability decreases from 8.53% to 3.53%. Furthermore, as can be seen from Appendix 3, when the film is at 90°C and unstretched, the film's solar light transmittance is only 48.51%. When the film is at 20°C and stretched 60%, the film's solar light transmittance reaches as high as 78.56%. When the Kirigami structure is unstretched, the pores are tightly closed, and the film's visible light transmittance and solar light modulation capability are similar to those of conventional thermochromic films (Sample 6). When the film is stretched, the pores deform, and the visible light transmittance increases significantly, with an increase of up to 43.1%. However, the rate of decrease in solar light transmittance is even faster, reaching 58.6%. Through the synergistic effect of the thermoinduced phase transition of VO2 and the kirigami structure, the solar modulation range of the smart window is increased to 30.05%, demonstrating that the introduction of the kirigami structure can expand the film's solar modulation range. Furthermore, before stretching, the kirigami film's visible light transmittance reaches 48.51%, exceeding the 40% visible light transmittance standard for windows. After stretching, the smart window's visible light transmittance continues to increase. In practical applications, increasing visible light transmittance can reduce the use of indoor lighting equipment and achieve energy savings.

[0084] According to the experimental results and working principles, it can be seen that the Kirigami structure VO2 smart window with active angle control set up by the present invention has high visible light transmittance and a large sunlight modulation range. It can also move and change its own angle as the angle of sunlight changes, so that the film is always perpendicular to the sunlight, thereby increasing the effective utilization area.

[0085] Example 2

[0086] A method for erecting a Kirigami structure VO2 smart window with active angle control is basically the same as Example 1, with the only difference being that in step 2, the ratio of the same-row pore distance d, the pore length l, and the adjacent-row spacing h is set to 1:8:1.

[0087] Example 3

[0088] A method for erecting a Kirigami structure VO2 smart window with active angle control is basically the same as Example 1, with the only difference being that in step 2, the ratio of the same-row pore distance d, the pore length l, and the adjacent-row spacing h is set to 1:10:1.

[0089] Example 4

[0090] A method for erecting a Kirigami structure VO2 smart window with active angle control is basically the same as Example 1, with the only difference being that in step 2, the ratio of the same-row pore distance d, the pore length l, and the adjacent-row spacing h is set to 1:9:0.5.

[0091] Example 5

[0092] A method for erecting a Kirigami structure VO2 smart window with active angle control is basically the same as Example 1, with the only difference being that in step 2, the ratio of the same-row pore distance d, the pore length l, and the adjacent-row spacing h is set to 1:9:2.

[0093] For the Kirigami structure VO2 film with staggered pores, changes in the pore length l, the distance d between pores in the same row, and the distance h between adjacent rows will change the Kirigami structure. The Kirigami structure VO2 smart window with active angle control set up in Examples 1 to 5 is used to control the servo motor to drive the lower adjustment plate to rotate, thereby controlling the stretching of the Kirigami structure VO2 film, and fitting the relationship between the stretching rate and the rotation angle during the process. The sum of the squared error (SSE) of the fitted curve measures the deviation between the predicted response and the actual response value. The closer to 0, the more accurate it is, and the determination coefficient (R-square) represents the degree of success of the fitting. The closer to 1, the higher the accuracy of the fitting. The adjusted adjusted determination coefficient (Adjusted R-square) represents the adjusted determination coefficient. The closer to 1, the more accurate the fitting. The fitting curves of Examples 1 to 3 are shown in Figure 2. Figure 12 As shown, the fitting curves of Example 1, Example 4 and Example 5 are as shown in Figure 13 The fitting results of Examples 1 to 5 are shown in Table 4.

[0094] Table 4 Fitting results

[0095]

[0096] From the results in Table 4, it can be seen that the fitting accuracy is high, especially in Example 1. According to the fitting results, when d and h are constant, as l increases, the rate of change of the film's rotation angle increases, and the film's stretchability increases; when l and d are constant, as h increases, the film's angle rotation rate increases rapidly, and the film's stretchability decreases. Figure 12 and Figure 13The rotation rate of the Kirigami VO2 film changes with the stretching ratio, initially increasing and then decreasing. As the rate slows, the film's deformation increases, gradually approaching its stretching limit. The Kirigami VO2 film of Example 1 has a moderate stretchability and controllable deformation, meeting practical needs. The Kirigami VO2 film of Example 4 can be stretched to approximately 280% of its original length, but the overall deformation is very large, making it difficult to meet practical application requirements. The Kirigami VO2 film of Example 5 exhibits a significantly reduced angular rotation rate, and stretching to 150% of its original length is close to its stretching limit.

[0097] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A Kirigami structure VO2 smart window with active angle control, characterized in that: It includes a window unit, a moving unit, a control unit, and a sensing unit; The window unit includes a Kirigami structure VO2 film, an upper fixing plate, and a lower adjusting plate. The upper fixing plate and the lower adjusting plate are respectively installed at both ends of the Kirigami structure VO2 film. The upper fixing plate is used to fix the Kirigami structure VO2 film on the window. The sensing unit is arranged on the side of the Kirigami structure VO2 film close to the window, and is used to track the angle of sunlight; The moving unit is connected to the lower adjustment plate and is used to move the Kirigami structure VO2 film; The control unit is connected to the moving unit and the sensing unit, and is used to move the Kirigami structure VO2 film according to the obtained sunlight angle, so that the Kirigami structure VO2 film is perpendicular to the sunlight.

2. The Kirigami structure VO2 smart window with active angle control according to claim 1, characterized in that: The method for preparing the Kirigami structure VO2 thin film includes: S1, mixing a film-forming agent and a dispersant-coated tungsten-doped VO2 to obtain a suspension; S2. Perform 3D photocuring printing to obtain a 50-800 μm Kirigami structure VO2 film.

3. The Kirigami structure VO2 smart window with active angle control according to claim 2, characterized in that: The film-forming agent is prepared by mixing a polyurethane acrylate prepolymer, a diluent and a photoinitiator; The mass ratio of polyurethane acrylate prepolymer, diluent and photoinitiator is 1:0.5-1.5:0.01-0.05; The diluent is an acrylate type diluent; The photoinitiator is at least one of TPO, photoinitiator 184, and photoinitiator 1173.

4. The Kirigami structure VO2 smart window with active angle control according to claim 2, characterized in that: The dispersant-coated tungsten-doped VO2 is obtained by wet ball milling tungsten-doped VO2 and a dispersant, and the mass ratio of the tungsten-doped VO2 to the dispersant is 1:0.5-1.

5.

5. The Kirigami structure VO2 smart window with active angle control according to claim 4, characterized in that: The dispersant includes at least one of polyvinyl pyrrolidone, triethylhexyl phosphate, sodium lauryl sulfate, methyl amyl alcohol, cellulose derivatives, polyacrylamide, guar gum, and fatty acid polyethylene glycol esters; The particle size of the tungsten-doped VO2 is 20-200 nm, and the tungsten doping amount is 1-5%.

6. The Kirigami structure VO2 smart window with active angle control according to claim 2, characterized in that: The 3D light-curing printing includes setting a layer thickness of 0.05 to 0.2 mm and a light-curing time of 3.0 to 12.0 seconds; It also includes setting the ratio of the distance d between pores in the same row, the pore length l and the distance h between adjacent rows.

7. The Kirigami structure VO2 smart window with active angle control according to claim 6, characterized in that: The ratio of the same-row pore distance d, pore length l and adjacent-row spacing h is 1:8-10:0.5-2.

8. The Kirigami structure VO2 smart window with active angle control according to any one of claims 1 to 7, characterized in that: The moving unit is a servo motor; The control unit is a single chip microcomputer; The sensing unit is a light sensing sensor; There are two light-sensing sensors, installed on the upper and lower ends of the Kirigami structure VO2 film respectively; If the light intensities captured by the two light sensors are different, a signal is transmitted to the microcontroller, which controls the rotation of the lower adjustment plate to control the movement of the Kirigami structure VO2 film until the light intensities of the two light sensors are the same. At this time, the Kirigami structure VO2 film is perpendicular to the sunlight.

9. The method for erecting the Kirigami structure VO2 smart window with active angle control according to claim 8, characterized in that: include, A light sensor is installed at the upper and lower ends of the Kirigami structure VO2 film; Install the upper fixing plate and the lower adjustment plate on the upper and lower ends of the Kirigami structure VO2 film, and then fix the upper fixing plate to the window; Connect the servo motor to the lower adjustment board, and connect the microcontroller to the servo motor and light sensor.

10. Application of the Kirigami structure VO2 smart window with active angle control according to any one of claims 1 to 8 in adjusting indoor light transmittance.

Images