Preparation method of device with adjustable dynamic emissivity

Abstract

The invention discloses a preparation method of a dynamic emissivity adjustable device, and relates to a preparation method of a dynamic emissivity device. The invention aims to solve the technical problem that the emissivity of an existing radiation refrigeration device cannot be adjusted. The invention provides a dynamic radiation refrigeration device based on silver nanowires. The prepared device is composed of the ITO surface attached with the nano silver wire, the electrolyte and the ITO, the nano silver wire shows excellent radiation regulation and control capacity in a specific wave band, and the radiation characteristic of the nano silver wire can be flexibly adjusted according to the change of the environment temperature by dynamically adjusting the morphology of the nano silver wire through design. In hot summer, the device can be adjusted to be high in emissivity, and the indoor temperature is effectively reduced. And in cold winter, the emissivity of the device can be reduced, so that heat loss is reduced, and the stability of indoor temperature is kept. Due to the dynamic adjustment characteristic, the method has a wide application prospect in the field of building energy conservation, such as energy-saving glass, skylight and the like.

Description

Technical Field

[0001] The invention relates to a method for preparing a dynamic emissivity device. Background Art

[0002] As the global population continues to grow, energy demand is rising dramatically. Maintaining thermal comfort has become a fundamental requirement of modern architecture and life, but this consumes significant amounts of energy, particularly in climate control and building thermal management. Therefore, improving energy efficiency and reducing energy consumption by reducing heat loss has become a key research topic for global energy conservation and emission reduction. In the construction sector, windows, as a crucial component of the building envelope, account for approximately 25% to 35% of energy losses. Ordinary glass, due to its high light transmittance, allows sunlight to penetrate indoors, heating objects while simultaneously absorbing and re-emitting thermal radiation, contributing to the greenhouse effect. While this property helps maintain indoor heat during cold seasons, it significantly increases cooling requirements during hot summers. Therefore, developing energy-saving window materials that combine high light transmittance with high thermal insulation has become a research priority.

[0003] Currently, energy-saving windows on the market are primarily achieved through two technologies: one is metal oxide thin films deposited using high-temperature pyrolysis chemical vapor deposition; the other is a thin metal layer protected by a dielectric material, deposited using magnetron sputtering. In addition, metal-based multilayer coatings and wide-bandgap doped semiconductors (such as indium tin oxide (ITO) and aluminum-doped zinc oxide (AZO)) are also widely used in the development of energy-saving windows. These materials have high transmittance in the visible light band and high reflectivity (i.e., low emissivity) in the infrared band, thereby reducing the loss of indoor thermal radiation to the outside. Radiative cooling technology offers an efficient and energy-saving solution, dissipating heat to the outside through radiative heat dissipation, thereby achieving a cooling effect. However, existing radiative cooling devices typically operate with a fixed emissivity and cannot flexibly respond to changes in environmental conditions. For example, in winter or low-temperature environments, these devices still maintain a high emissivity, which can lead to overcooling and reduce indoor thermal comfort. Summary of the Invention

[0004] The present invention aims to solve the technical problem that the existing radiative cooling device cannot adjust the emissivity, and provides a method for preparing a device with dynamic emissivity adjustment.

[0005] The preparation method of the dynamic emissivity adjustable device of the present invention is carried out according to the following steps:

[0006] 1. Preparation of silver nanowires using the polyol method;

[0007] 2. Electrode coating: The silver nanowires prepared in step 1 were mixed with PMMA, PVA and anisole, stirred thoroughly and then mixed with isopropyl alcohol in a volume ratio of 1:(1-100), magnetically stirred for 1h-1.5h, and then coated on a cleaned ITO conductive glass;

[0008] The molar ratio of the silver nanowire to PMMA, PVA and anisole is 1:(0.02-1):(0.1-10):(0.01-100);

[0009] 3. Cavity construction: Place the ITO conductive glass modified with nanosilver wires in step 2 opposite to another clean ITO conductive surface, add solid SiO2 microspheres as spacers between the ITO conductive glass, use UV curing glue to bond along the edge of the glass, leaving a small opening when applying the glue, and seal the small opening left in step 3 with UV curing glue. Curing again under UV light to ensure the airtightness of the device, place it under UV light for irradiation to completely cure the glue and form a closed cavity;

[0010] 4. Electrolyte injection: Mix DMSO, sodium citrate, polyvinyl pyrrolidone, ammonium bromide, potassium chloride and water to obtain an electrolyte. Use a syringe to inject the electrolyte into the cavity through the small opening left in step 3, remove bubbles, and ensure that the mixture is in full contact with the ITO conductive glass to obtain the device.

[0011] The molar ratio of DMSO, sodium citrate, polyvinylpyrrolidone, ammonium bromide and potassium chloride is 1:(0.2-100):(0.001-80):(0.001-100):(0.2-100);

[0012] The concentration of sodium citrate in the electrolyte is 0.002 mol / L.

[0013] The device prepared by the present invention consists of an ITO surface with silver nanowires attached, an electrolyte and ITO. During the preparation process, two ITO sheets are bonded together with a gel electrolyte sandwiched in between, and are cured with ultraviolet curing glue around them to ensure the airtightness of the device.

[0014] The device with adjustable dynamic emissivity prepared by the present invention has conductive copper tape attached to the conductive surfaces of two conductive substrates, namely ITO, directly connecting the positive and negative electrodes. When an oxidation voltage (1.2V to 3V) is applied to the device, the silver nanowires on the surface of the device electrodes will be oxidized and dissolved to form a solution. At this time, since the silver nanowires on the surface are dissolved, the device is transparent (i.e., a high emissivity state); when a reduction voltage (0.3V to -1.2V) is applied, the silver ions in the device are reduced to silver element. It is worth noting that since surfactants (sodium citrate, polyvinyl pyrrolidone, ammonium bromide) that control the anisotropic growth of silver wires are added to the electrolyte, the surface energy of the silver wires is changed, thereby ensuring that silver nanowires can be obtained in the second reduction process. At this time, the surface silver wires make the device have a lower emissivity. In summary, the emissivity of the device can be adjusted by adjusting the oxidation / reduction voltage.

[0015] This invention proposes a dynamic radiative cooling device based on silver nanowires. The silver nanowires exhibit excellent radiative control capabilities within specific wavelengths. By dynamically adjusting the nanowire morphology, their radiation characteristics can be flexibly adjusted according to ambient temperature fluctuations. In hot summer weather, the device can be adjusted to a higher emissivity, effectively lowering the indoor temperature. In cold winter weather, the device's emissivity can be lowered to minimize heat loss and maintain a stable indoor temperature. This dynamic adjustment property holds great promise for applications in building energy conservation, such as in energy-saving glass and skylights. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the operation of the dynamic emissivity adjustable device of the present invention. DETAILED DESCRIPTION

[0017] Specific embodiment 1: This embodiment is a method for preparing a dynamic emissivity adjustable device, which is specifically carried out according to the following steps:

[0018] 1. Preparation of silver nanowires using the polyol method;

[0019] 2. Electrode coating: The silver nanowires prepared in step 1 were mixed with PMMA, PVA and anisole, stirred thoroughly and then mixed with isopropyl alcohol in a volume ratio of 1:(1-100), magnetically stirred for 1h-1.5h, and then coated on a cleaned ITO conductive glass;

[0020] The molar ratio of the silver nanowire to PMMA, PVA and anisole is 1:(0.02-1):(0.1-10):(0.01-100);

[0021] 3. Cavity Construction: Place the ITO conductive glass modified with silver nanowires in step 2 opposite to another clean ITO conductive surface. Add solid SiO2 microspheres as spacers between the ITO conductive glass and use UV-curing glue to bond along the edges of the glass, leaving a small opening when applying the glue. Place it under UV light to completely cure the glue and form a sealed cavity.

[0022] 4. Electrolyte injection: Mix DMSO, sodium citrate, polyvinyl pyrrolidone, ammonium bromide, potassium chloride and water to obtain an electrolyte. Use a syringe to inject the electrolyte into the cavity through the small opening left in step 3, remove bubbles, and ensure that the mixture is in full contact with the ITO conductive glass. Seal the small opening left in step 3 with UV curable adhesive, and cure it again under UV light to ensure the airtightness of the device. The device can be obtained;

[0023] The molar ratio of DMSO, sodium citrate, polyvinylpyrrolidone, ammonium bromide and potassium chloride is 1:(0.2-100):(0.001-80):(0.001-100):(0.2-100);

[0024] The concentration of sodium citrate in the electrolyte is 0.002 mol / L.

[0025] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the method for preparing silver nanowires using the polyol method in step 1 is as follows:

[0026] 1 mL to 100 mL of ethylene glycol and 0.01 g to 200 g of sodium chloride are mixed and stirred, heated to 200° C. and kept warm for 1 hour, then 20 mL to 300 mL of a 0.05 mol / L to 18 mol / L CuCl2 solution is added, heated to 200° C. and kept warm for 1 hour; then 20 μL of a 0.01 mol / L polyvinyl pyrrolidone solution is added, followed by 10 mL to 100 mL of a 0.0003 mol / L to 2 mol / L AgNO3 solution, stirred for 30 minutes, washed several times in acetone and isopropanol to remove impurities, and dried to obtain silver nanowires (AgNWs). Other aspects are the same as those in the first embodiment.

[0027] Specific embodiment 3: This embodiment differs from specific embodiment 1 or 2 in that in step 2, the coating is applied on a cleaned ITO conductive glass by spin coating, dip coating or spray coating. Other aspects are the same as specific embodiment 1 or 2.

[0028] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that in step 3, solid SiO2 microspheres are added between the ITO conductive glass as spacers, with a thickness of 10 μm to 50 μm to ensure the stability of the cavity structure. Other aspects are the same as specific embodiments 1 to 3.

[0029] Specific embodiment 5: This embodiment differs from specific embodiment 4 in that in step 3, the adhesive is completely cured under ultraviolet light for 10 to 15 minutes to form a sealed cavity. Other aspects are the same as specific embodiment 4.

[0030] Specific embodiment 6: This embodiment differs from specific embodiment 5 in that the method for removing bubbles in step 4 is vacuuming. Other aspects are the same as specific embodiment 5.

[0031] The present invention is verified by the following test:

[0032] Experiment 1: This experiment is a method for preparing a dynamic emissivity adjustable device, which is specifically carried out in the following steps:

[0033] 1. Preparation of silver nanowires using the polyol method:

[0034] 50 mL of ethylene glycol and 100 g of sodium chloride were mixed and stirred, heated to 200°C and kept warm for 1 hour, then 100 mL of 10 mol / L CuCl2 solution was added, heated to 200°C and kept warm for 1 hour; then 20 μL of 0.01 mol / L polyvinyl pyrrolidone solution was added, and then 50 mL of 1 mol / L AgNO3 solution was added, stirred for 30 minutes, washed several times in acetone and isopropanol to remove impurities, and dried to obtain silver nanowires AgNWs;

[0035] 2. Electrode coating: The silver nanowires prepared in step 1 were mixed with PMMA, PVA and anisole, stirred thoroughly and then mixed with isopropyl alcohol at a volume ratio of 1:50. The mixture was magnetically stirred for 1 hour and then spin-coated on a cleaned ITO conductive glass.

[0036] The molar ratio of the silver nanowire to PMMA, PVA and anisole is 1:0.5:5:50;

[0037] 3. Cavity Construction: Place the ITO conductive glass modified with silver nanowires in step 2 opposite to another clean ITO conductive surface. Add solid SiO2 microspheres as spacers between the ITO conductive glasses with a thickness of 20 μm to ensure the stability of the cavity structure. Use UV-curable glue to bond along the edges of the glass, leaving a small opening when applying the glue. Place it under UV light for 12 minutes to completely cure the glue and form a sealed cavity.

[0038] 4. Electrolyte injection: DMSO, sodium citrate, polyvinyl pyrrolidone, ammonium bromide, potassium chloride and water are mixed to obtain an electrolyte. The electrolyte is injected into the cavity through the small opening left in step 3 using a syringe. Air bubbles are removed by vacuuming to ensure that the mixture is in full contact with the ITO conductive glass. The small opening left in step 3 is sealed with UV curable adhesive and cured again under UV light to ensure the airtightness of the device. The device is then obtained.

[0039] The molar ratio of DMSO, sodium citrate, polyvinyl pyrrolidone, ammonium bromide and potassium chloride is 1:50:10:20:40;

[0040] The concentration of sodium citrate in the electrolyte is 0.002 mol / L.

[0041] The device prepared in this experiment consists of an ITO surface with attached silver nanowires, an electrolyte, and ITO. During the preparation process, two ITO sheets are bonded together with a gel electrolyte sandwiched in the middle, and UV-curable adhesive is used to cure the surrounding areas to ensure the airtightness of the device.

[0042] The device fabricated in this experiment features a dynamically adjustable emissivity. Conductive copper tape is applied to the conductive surfaces of two conductive substrates, namely, ITO, directly connecting the positive and negative electrodes. When an oxidation voltage (1.2V to 3V) is applied to the device, the silver nanowires on the surface of the device electrodes are oxidized and dissolved, forming a solution. At this point, the device becomes transparent due to the dissolution of the surface silver nanowires. When a reduction voltage (0.3V to -1.2V) is applied, the silver ions in the device are reduced to elemental silver. Notably, the addition of surfactants (sodium citrate, polyvinylpyrrolidone, and ammonium bromide) to the electrolyte, which control the anisotropic growth of silver nanowires, alters the surface energy of the silver nanowires, ensuring that silver nanowires can be obtained during the subsequent reduction process. In this case, the surface silver wires lower the device's emissivity. In summary, the device's emissivity can be adjusted by adjusting the oxidation / reduction voltage.

[0043] This experiment proposed a dynamic radiative cooling device based on silver nanowires. The silver nanowires exhibit excellent radiative control capabilities within specific wavelengths. By dynamically adjusting the silver nanowire morphology, their radiative properties can be flexibly adjusted according to ambient temperature fluctuations. In hot summer weather, the device can be adjusted to a higher emissivity, effectively lowering the indoor temperature. In cold winter weather, the device's emissivity can be lowered to minimize heat loss and maintain a stable indoor temperature. This dynamic adjustment property holds great promise for applications in building energy efficiency, such as energy-saving glass and skylights.

Claims

1. A method for preparing a dynamic emissivity adjustable device, characterized in that The preparation method of the dynamic emissivity adjustable device is carried out according to the following steps:

1. Preparation of silver nanowires using the polyol method; 2. Electrode coating: The silver nanowires prepared in step 1 were mixed with PMMA, PVA and anisole, and the mixture was thoroughly stirred and mixed with isopropyl alcohol in a volume ratio of 1:(1-100), and magnetically stirred for 1h-1.5h, and then coated on a cleaned ITO conductive glass; The molar ratio of the silver nanowire to PMMA, PVA and anisole is 1:(0.02-1):(0.1-10):(0.01-100); 3. Cavity Construction: Place the ITO conductive glass modified with silver nanowires in step 2 opposite to another clean ITO conductive surface. Add solid SiO2 microspheres as spacers between the ITO conductive glass and use UV-curing glue to bond along the edges of the glass, leaving a small opening when applying the glue. Place it under UV light to completely cure the glue and form a sealed cavity.

4. Electrolyte injection: Mix DMSO, sodium citrate, polyvinyl pyrrolidone, ammonium bromide, potassium chloride and water to obtain an electrolyte. Use a syringe to inject the electrolyte into the cavity through the small opening left in step 3, remove bubbles, and ensure that the mixture is in full contact with the ITO conductive glass. Seal the small opening left in step 3 with UV curable adhesive, and cure it again under UV light to ensure the airtightness of the device. The device can be obtained; The molar ratio of DMSO, sodium citrate, polyvinylpyrrolidone, ammonium bromide and potassium chloride is 1:(0.2-100):(0.001-80):(0.001-100):(0.2-100); The concentration of sodium citrate in the electrolyte is 0.002 mol / L.

2. The method for preparing a dynamic emissivity adjustable device according to claim 1, characterized in that The method for preparing silver nanowires using the polyol method in step 1 is as follows: 1mL~100mL of ethylene glycol and 0.01g~200g of sodium chloride are mixed and stirred, heated to 200℃ and kept warm for 1h, then 20mL~300mL of CuCl2 solution with a concentration of 0.05mol / L~18mol / L is added, heated to 200℃ and kept warm for 1h; then 20μL of polyvinylpyrrolidone solution with a concentration of 0.01mol / L is added, and then 10mL~100mL of AgNO3 solution with a concentration of 0.0003mol / L~2mol / L is added, stirred for 30min, washed several times in acetone and isopropanol to remove impurities, and dried to obtain nanosilver wires AgNWs.

3. The method for preparing a dynamic emissivity adjustable device according to claim 1, characterized in that In step 2, the film is coated on a cleaned ITO conductive glass by spin coating, dip coating or spray coating.

4. The method for preparing a dynamic emissivity adjustable device according to claim 1, characterized in that In step three, solid SiO2 microspheres are added between the ITO conductive glass as spacers, with a spacing thickness of 10 μm to 50 μm to ensure the stability of the cavity structure.

5. The method for preparing a dynamic emissivity adjustable device according to claim 1, characterized in that In step three, the adhesive is irradiated under a UV lamp for 10 to 15 minutes to completely cure and form a sealed cavity.

6. The method for preparing a dynamic emissivity adjustable device according to claim 1, characterized in that The method for removing bubbles in step 4 is vacuuming.

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