Liquid phase transformed optical metamaterial perfect absorber and method of making the same

Abstract

The application discloses a liquid-phase conversion optical metamaterial perfect absorber and a preparation method thereof. The light-absorbing layer of the optical metamaterial perfect absorber is prepared by combining a liquid-phase conversion solution, a sol-gel method and a nano-imprinting method. The liquid-phase conversion solution significantly improves process compatibility. The light-absorbing layer can be coated on different substrates at low temperature by the sol-gel method or a coating method, and has good process compatibility and preparation flexibility. Meanwhile, the solution gel method and the micro-nano patterning technology (nano-imprinting method) are adopted to effectively reduce production cost, and have high industrialization adaptability.

Description

Technical Field

[0001] This invention belongs to the field of energy conversion technology, specifically relating to a perfect absorber of optical metamaterials that undergoes liquid-phase conversion and its preparation method. Background Technology

[0002] The fundamental principle of a perfect absorber lies in its specially designed microstructure and material properties, enabling efficient absorption of solar radiation and conversion of light energy into heat energy. The release of this heat radiation is then controlled through narrowband selective emission. Exhibiting high absorptivity across a broad spectrum (e.g., 0.3 to 2.5 μm), it significantly reduces reflection losses, making it suitable for applications in high-efficiency energy conversion fields such as solar thermal photovoltaic (STPV) systems, industrial waste heat recovery, and spacecraft thermal management. In STPV systems, the perfect absorber effectively absorbs solar radiation and converts it into heat energy, which is then further converted into electrical energy through thermophotovoltaic cells, thereby improving the efficiency of solar energy utilization. It also plays a crucial role in industrial waste heat recovery and thermal protection of aerospace equipment, reducing energy loss and extending equipment lifespan.

[0003] High-temperature metamaterial perfect absorbers face several challenges in current technology: First, poor process compatibility, as traditional ceramic materials are difficult to fabricate microstructure layers on semiconductor chips; second, limited material selection, mainly relying on high-cost precious metals or special ceramics; and third, complex and expensive fabrication methods, resulting in long manufacturing cycles and high costs. These problems directly affect the promotion and widespread adoption of perfect absorbers in practical applications. The difficulty of fabricating microstructure layers on semiconductor chips using traditional ceramic materials poses a challenge to the integration of multilayer structures. Chen Shuangjun et al. pointed out in their research that traditional ceramic materials, due to pyrolysis requirements and material incompatibility, cannot directly form microstructure layers on the chip surface. Secondly, limited material selection affects the performance of high-temperature absorbers. Many studies rely on high-melting-point metals, such as tungsten and molybdenum. Although these materials perform excellently at high temperatures, their high cost limits the feasibility of large-scale applications. Daniel et al. pointed out in their research that while tungsten as an absorber material possesses good thermal stability, its high production cost limits practical applications. Furthermore, the complexity and expense of fabrication methods make it difficult to realize many high-performance absorbers in industrial processes. In his research, Wang Jie mentioned that although magnetron sputtering can prepare highly selective absorption coatings, its complex process, high production cost, and low efficiency have limited its large-scale application. Summary of the Invention

[0004] The purpose of this invention is to provide a perfect absorber of optical metamaterials by liquid-phase conversion and its preparation method. The light-absorbing layer is prepared by liquid-phase conversion ceramics, and microstructures are formed on the light-absorbing layer by sol-gel method and nanoimprinting method. Then, the inorganic ceramic light-absorbing layer is obtained by pyrolysis. It has good process compatibility and preparation flexibility, and also has the advantages of simple preparation process and low production cost.

[0005] The technical solution of the present invention is as follows:

[0006] A liquid-phase conversion optical metamaterial perfect absorber, which from bottom to top includes a substrate, an insulating layer and a light-absorbing layer, the light-absorbing layer being a ceramic thin film with several microstructures;

[0007] The light-absorbing layer is obtained by forming a sol film with several microstructures from a liquid phase conversion solution through solution-gel method and nanoimprinting method, and then pyrolyzing it at 700-1000℃;

[0008] The liquid-phase conversion solution includes a doped phase and a polymer ceramic precursor. The doped phase is at least one of carbon nanotubes, graphene, silicon carbide, titanium carbide, silicon nitride, boron nitride, indium tin oxide, and zirconium oxide. The polymer ceramic precursor is a silicon-based precursor.

[0009] The amount of dopant added is 35-70 wt% of the solids in the liquid-phase conversion solution, and the average particle size of the dopant is 1 nm-100 μm.

[0010] In some possible implementations, the microstructure is at least one of a pyramid structure, an inverted pyramid structure, and a nanopillar array structure.

[0011] In some possible implementations, the doping phase is indium tin oxide, and the polymer ceramic precursor is polysilazane.

[0012] In some possible implementations, the adhesion strength between the substrate and the insulating layer, and between the insulating layer and the light-absorbing layer, is greater than 6.65 MPa.

[0013] In some possible implementations, the thickness of the light-absorbing layer is 500 nm-10 μm, and the thickness of the insulating layer is 10-200 μm.

[0014] In some possible implementations, the insulating layer is made of a high-temperature insulating material, including at least one of aluminum oxide, magnesium oxide, boron nitride, and silicon oxide.

[0015] In some possible implementations, the substrate is a metal substrate. Preferably, the substrate is a nickel-based alloy substrate, a stainless steel substrate, or a tungsten substrate.

[0016] A method for preparing the above-mentioned perfect absorber of optical metamaterial includes the following steps:

[0017] (1) The substrate is ultrasonically cleaned and then dried;

[0018] (2) Spin-coat or heat-insulating material on the substrate, cure and crosslink at 100-200℃ for 30-60 min, then heat to 800-1000℃ at a heating rate of 5-10℃ / min and keep warm for 1-2 h to obtain the insulating layer.

[0019] (3) The doped phase and polymer ceramic precursor are mixed in proportion and dispersed in an organic solvent. After magnetic stirring and ultrasonication, a uniformly mixed and bubble-free liquid phase conversion solution is obtained.

[0020] (4) Spin-coating the phase inversion solution onto the insulating layer and then drying it at 60-100°C to obtain a sol film.

[0021] (5) Place the sol film in a mold with microstructures, and imprint the microstructures on the surface of the sol film using nanoimprinting technology. The imprinting temperature is 100-200℃. Finally, pyrolyze the sol film with the imprinted microstructures at 700-1000℃ for 1 hour to obtain the final product.

[0022] In some possible implementations, the mold is made of silicon or metal.

[0023] In some possible implementations, the organic solvent in step (3) is acetone.

[0024] The present invention has at least the following beneficial effects:

[0025] The light-absorbing layer of the perfect absorber in the optical metamaterial provided by this invention is prepared by combining a liquid-phase inversion solution with a sol-gel method and a nanoimprinting method. The liquid-phase inversion solution used significantly improves process compatibility, allowing it to be coated onto different substrates at low temperatures via the sol-gel method or coating method, exhibiting good process compatibility and preparation flexibility. Simultaneously, the use of solution gelation and micro / nano patterning technology (nanoimprinting) effectively reduces production costs, demonstrating high industrial adaptability.

[0026] Furthermore, the liquid-phase conversion solution comprises a polymer ceramic precursor and a doped phase. Through the formulation and pyrolysis process of the liquid-phase conversion solution, liquid-phase conversion ceramics can achieve structural designs from the micrometer to the nanometer scale, thereby improving the light-harvesting efficiency of the absorber. Specifically, the microstructures on the surface of the light-absorbing layer can effectively increase the multiple reflection paths of light, thereby improving its light absorption rate and light-harvesting efficiency.

[0027] Finally, using the doped phase as a high-temperature durability component in the liquid-phase conversion solution enhances the absorber's oxidation resistance and thermal stability in high-temperature environments. This allows the perfect absorber of optical metamaterials to maintain good physical and chemical stability and excellent oxidation resistance at high temperatures, adapting to environments above 1000℃. This is crucial for high-temperature applications such as solar thermal photovoltaic systems (STPV) and industrial waste heat recovery. The process of converting the polymer precursor into ceramic material through the liquid-phase conversion solution avoids the structural degradation problems commonly encountered during pyrolysis. Attached Figure Description

[0028] Figure 1 This is a process flow diagram of Embodiment 1 of the present invention;

[0029] Figure 2 This is a film structure of a liquid-phase conversion optical metamaterial perfect absorber according to Embodiment 1 of the present invention;

[0030] Figure 3 This is a schematic diagram of the microstructure of the light-absorbing layer in Embodiment 1 of the present invention;

[0031] Figure 4 The incident rate of light for the perfect absorber of the optical metamaterial of this invention;

[0032] Figure 5 The transmittance of light is the perfect absorber of the optical metamaterial of this invention.

[0033] The reference numerals in the figure are: 1-substrate, 2-insulating layer, 3-light-absorbing layer. Detailed Implementation

[0034] The technical solution of the present invention will be further explained and described below through specific embodiments.

[0035] In the following embodiments, the water used can be one or more of distilled water, purified water, and drinking water; unless otherwise specified, the detection methods in the following embodiments are conventional detection methods; unless otherwise specified, the reagents in the following embodiments are all purchased from commercial channels.

[0036] Example 1

[0037] A method for preparing a perfect absorber from optical metamaterials, such as Figure 1 As shown, it includes the following steps:

[0038] (1) Clean the nickel-based alloy substrate with acetone, alcohol and deionized water in sequence, sonicate for 5 minutes in sequence, and place it in a vacuum drying oven to dry the substrate.

[0039] (2) Alumina insulating slurry was spin-coated onto the substrate by screen printing. The substrate was placed on a heating table and heated to 200°C for half an hour to cure and crosslink. Then it was placed in a tube furnace and heated to 800°C at a heating rate of 5°C / min. The temperature was maintained for 1 hour for high-temperature annealing. The thickness of the insulating layer was 100μm.

[0040] (3) Polysilazane, indium tin oxide (ITO) with a particle size of 50 μm and acetone are mixed in a mass ratio of 1:4:2. After magnetic stirring and sonication, a uniform liquid-phase conversion solution without bubbles is obtained.

[0041] (4) The liquid phase conversion solution obtained in step (3) is screen-printed onto the insulating layer and then placed in an oven at 60°C to dry in order to remove the solvent and ensure that the film layer is uniformly cured, resulting in a sol film with a thickness of 5 μm.

[0042] (5) Prepare a mold with a pyramid-shaped microstructure made of silicon. Then, bring the sol-gel film prepared in step (4) into close contact with the mold, and imprint the pyramid-shaped micro / nanostructure onto the film surface by high-pressure heating. The imprinting process is carried out at a temperature of 200°C. The imprinted sol-gel film with the microstructure is then placed in a tube furnace for pyrolysis to obtain the following... Figure 2 and Figure 3 The optical metamaterial perfect absorber shown is sintered at a temperature of 1000℃ for 1 hour.

[0043] Example 2

[0044] A method for preparing a perfect absorber from optical metamaterials includes the following steps:

[0045] (1) Clean the stainless steel substrate with acetone, alcohol and deionized water in sequence, sonicate for 5 minutes in sequence, and place it in a vacuum drying oven to dry the substrate.

[0046] (2) Alumina insulating paste was spin-coated onto the substrate by screen printing. The paste was placed on a heating table and heated to 200°C for half an hour to cure and crosslink, thus obtaining an insulating layer. The insulating layer was then heat-treated by placing it in a tube furnace and heating it at a rate of 10°C / min until it reached 1000°C. The furnace was then held at the temperature for 2 hours for high-temperature annealing, resulting in an insulating layer thickness of 100μm.

[0047] (3) Polysilazane, indium tin oxide with a particle size of 50 μm and acetone are mixed in a mass ratio of 1:4:2. After magnetic stirring and ultrasonication, a uniform liquid-phase conversion solution without bubbles is obtained.

[0048] (4) The liquid phase conversion solution obtained in step (3) is screen-printed onto the insulating layer and then placed in an oven at 60°C to dry in order to remove the solvent and ensure that the film layer is uniformly cured, resulting in a sol film with a thickness of 5 μm.

[0049] (5) Prepare a mold with a pyramid-shaped microstructure made of silicon. Then, the sol-gel film prepared in step (4) is brought into close contact with the mold, and the pyramid-shaped micro / nanostructure is imprinted onto the film surface by high-pressure heating. The imprinting process is carried out at a temperature of 200°C. The imprinted sol-gel film with microstructure is placed in a tube furnace for pyrolysis, and the sintering temperature is 1000°C for 1 hour.

[0050] Example 3

[0051] A method for preparing a perfect absorber from optical metamaterials includes the following steps:

[0052] (1) Clean the nickel-based alloy substrate with acetone, alcohol and deionized water in sequence, sonicate for 5 minutes in sequence, and place it in a vacuum drying oven to dry the substrate.

[0053] (2) An alumina thin film insulating layer was deposited on the substrate using chemical vapor deposition, in stages to a total thickness of 100 μm, with each deposition being 10-20 μm thick. After each deposition, the film was placed on a heating stage and heated to 200°C for 30 minutes to ensure film uniformity and initial strength. Subsequently, the deposited insulating layer was subjected to high-temperature annealing, placed in a tube furnace and heated at a rate of 3°C / min to 800°C, and held at that temperature for 1 hour.

[0054] (3) Polysilazane, indium tin oxide with a particle size of 50 μm and acetone are mixed in a mass ratio of 1:4:2. After magnetic stirring and ultrasonication, a uniform liquid-phase conversion solution without bubbles is obtained.

[0055] (4) The liquid phase conversion solution obtained in step (3) is screen-printed onto the insulating layer and then placed in an oven at 60°C to dry in order to remove the solvent and ensure that the film layer is uniformly cured, resulting in a sol film with a thickness of 5 μm.

[0056] (5) Prepare a mold with a pyramid-shaped microstructure made of silicon. Then, the sol-gel film prepared in step (4) is brought into close contact with the mold, and the pyramid-shaped micro / nanostructure is imprinted onto the film surface by high-pressure heating. The imprinting process is carried out at a temperature of 200°C. The imprinted sol-gel film with microstructure is placed in a tube furnace for pyrolysis, and the sintering temperature is 1000°C for 1 hour.

[0057] Example 4

[0058] The optical metamaterial perfect absorber prepared in Example 1 was subjected to light absorption rate testing. The formula for calculating the light absorption rate is: light absorption rate = 1 - incident rate - transmittance.

[0059] An incident and transmittance were measured using a spectrophotometer. An integrating sphere attachment was used to place the sample in the optical path, and the reflected light from the sample surface was captured to obtain the reflected light intensity at various wavelengths. Figure 4 This study compares the incident light intensity of undoped and ITO-doped liquid phase conversion ceramics within the target wavelength range. It ensures that the incident light is completely captured by the integrating sphere to obtain the true reflection value. The sample is placed in the optical path, and the light intensity transmitted through the sample is measured. The wavelength setting of the spectrophotometer is adjusted to scan the target wavelength range (800nm-2500nm) to obtain the transmitted light at each wavelength, such as... Figure 5 The transmitted light intensity is compared between undoped and ITO-doped liquid-phase conversion ceramics within the target wavelength range. It can be seen that efficient light absorption can be achieved over a wide spectral range.

[0060] The above description is merely a preferred embodiment of the present invention, and therefore should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the patent and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A liquid phase converted optical metamaterial perfect absorber comprising, in order from bottom to top, a substrate, an insulating layer, and a light absorbing layer, characterized in that, The light-absorbing layer is a ceramic film with microstructures; The light-absorbing layer is formed by a solution-gel method and a nano-imprinting method to form a sol film with microstructures from a liquid phase conversion solution, and pyrolysis at 700-1000℃ is performed to obtain the light-absorbing layer; The liquid phase conversion solution comprises a doped phase and a polymer ceramic precursor, the doped phase is at least one of carbon nanotubes, graphene, silicon carbide, titanium carbide, silicon nitride, boron nitride, indium tin oxide and zirconium oxide, and the polymer ceramic precursor is a silicon-based precursor. The addition amount of the doped phase is 35-70wt% of the solid content in the liquid phase conversion solution, and the average particle size of the doped phase is 1nm-100μm.

2. The optical metamaterial perfect absorber of claim 1, wherein, The microstructure is at least one of a pyramid structure, an inverted pyramid structure and a nano-pillar array structure.

3. The optical metamaterial perfect absorber of claim 1 or 2, wherein, The doped phase is indium tin oxide, and the polymer ceramic precursor is polysilazane.

4. The optical metamaterial perfect absorber of claim 1, wherein, The adhesion strength between the substrate and the insulating layer, and between the insulating layer and the light-absorbing layer is greater than 6.65MPa.

5. The optical metamaterial perfect absorber of claim 1, wherein, The thickness of the light-absorbing layer is 500nm-10μm, and the thickness of the insulating layer is 10-200μm.

6. The optical metamaterial perfect absorber of claim 1, wherein, The insulating layer is made of a high-temperature insulating material, and the high-temperature insulating material comprises at least one of aluminum oxide, magnesium oxide, boron nitride and silicon oxide.

7. The optical metamaterial perfect absorber of claim 1, wherein, The substrate is a metal substrate.

8. The optical metamaterial perfect absorber of claim 7, wherein, The substrate is a nickel-based alloy substrate, a stainless steel substrate or a tungsten substrate.

9. A method of producing the optical metamaterial perfect absorber according to any one of claims 1 to 7, characterized by, The method comprises the following steps: (1) ultrasonic cleaning and drying the substrate; (2) spin coating or high-temperature deposition of a high-temperature insulating material on the substrate, curing and crosslinking at 100-200℃ for 30-60min, then heating at a temperature increasing rate of 5-10℃ / min to 800-1000℃, and holding for 1-2h to obtain an insulating layer; (3) mixing the doped phase and the polymer ceramic precursor in proportion and dispersing them in an organic solvent, then magnetically stirring and ultrasonicating to obtain a liquid phase conversion solution which is uniformly mixed and bubble-free; (4) spin coating the phase conversion solution on the insulating layer, and then drying at 60-100℃ to obtain a sol film; (5) placing the sol film in a mold with microstructures, and imprinting the microstructures on the surface of the sol film by a nano-imprinting technology, the imprinting temperature is 100-200℃, and finally pyrolyzing the sol film with imprinted microstructures at 700-1000℃ for 1-3h to obtain the light-absorbing layer.

10. The production method according to claim 9, wherein The material of the mold is silicon or metal.

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