阅读说明：本技术 一种微纳多孔陷光结构及其制备方法 (Micro-nano porous light trapping structure and preparation method thereof ) 是由 王啸 李朝龙 朴明星 史浩飞 于 2021-07-02 设计创作，主要内容包括：本发明的目的是提供一种微纳多孔陷光结构及其制备方法。即针对传统制备工艺中对选择性光学吸收结构精确控制性较差的缺点,提供了一种尺寸可精准调控的多孔光学吸收结构及其制备方法,通过引入标准尺寸的致孔剂构建尺度精准的光学吸收结构,该结构与目标吸收光源的波长尺度精准匹配,实现在该特定波段下的高效光学吸收。(The invention aims to provide a micro-nano porous light trapping structure and a preparation method thereof. Aiming at the defect that the selective optical absorption structure in the traditional preparation process is poor in accurate control performance, the porous optical absorption structure with the size capable of being accurately regulated and controlled and the preparation method thereof are provided.)

1. A preparation method of a micro-nano porous light trapping structure is characterized by comprising the following steps:

(1) preparing micron-sized or nano-sized inorganic particles as a pore-foaming agent;

(2) dispersing and embedding inorganic particles on the surface of a polymer template;

(3) and after inorganic particles are removed by etching, a porous light trapping structure is formed on the surface of the polymer template.

2. The preparation method of the micro-nano porous light trapping structure according to claim 1, characterized by comprising the following steps: the step (1) comprises the following steps:

(1-1) preparation of inorganic particle Dispersion: mixing and grinding inorganic particle silicon dioxide, deionized water, a surfactant and an alkaline stabilizer to prepare silicon dioxide dispersion liquid;

wherein, the mixture ratio of each component is as follows:

100 portions of silicon dioxide

8000 portions and 9900 portions of deionized water

2-500 parts of nonionic surfactant

1-500 parts of alkaline stabilizer

(1-2) preparation of immersion liquid: mixing the silicon dioxide dispersion liquid with the polytetrafluoroethylene emulsion to prepare a soaking liquid;

wherein, the mixture ratio of each component is as follows:

10-99 parts of silicon dioxide dispersion liquid

2-90 parts of polytetrafluoroethylene emulsion

2-80 parts of impregnating solution.

3. The preparation method of the micro-nano porous light trapping structure according to claim 2, characterized by comprising the following steps: the step (2) comprises the following steps:

(2-1) soaking of the polymer template:

cleaning the surface of a polytetrafluoroethylene high-molecular template, immersing the template into the impregnating solution obtained in the step (1-2), and drying to obtain coupled particles of silicon dioxide and polytetrafluoroethylene distributed on the surface of the template;

(2-2) particle intercalation:

and (3) carrying out heat treatment on the polytetrafluoroethylene polymer template treated in the step (2-1) to embed the coupling particles into the surface layer of the template, and then slowly cooling the template to room temperature.

4. The preparation method of the micro-nano porous light trapping structure according to claim 2 or 3, characterized by comprising the following steps: and (3) etching the surface of the template obtained by the treatment in the step (2-2) by using hydrofluoric acid, ultrasonically cleaning the template by using deionized water or ethanol solution, and drying the template to obtain the porous structure.

5. The method for preparing a micro-nano porous light trapping structure according to claim 2 or 4, wherein in the step (1-1):

the inorganic particles are nano or micron-sized silica particles with standard sizes;

the grinding mode is a sand grinding method or a ball grinding method;

the surfactant is a nonionic surfactant or an amphoteric surfactant which is nonionic under alkaline conditions;

the alkaline stabilizer is metal hydroxide;

the pH of the dispersion was 7-9.

6. The method for preparing a micro-nano porous light trapping structure according to claim 5, wherein in the step (1-1):

the grain size of the nano-scale silicon dioxide is 100-950nm, and the grain size of the micro-scale silicon dioxide is 1-30 μm;

in the grinding mode, the grinding time of the sand grinding method is 1-5 hours. Grinding for 3-20 hours by a ball milling method;

the nonionic surfactant is selected from polyethylene glycol octyl phenyl ether and alkylphenol polyoxyethylene ether;

the amphoteric surfactant which is nonionic under alkaline condition is alkyl amine oxide surfactant;

the metal hydroxide is selected from aluminum hydroxide or copper hydroxide;

in the step (1-2):

the solid content of the polytetrafluoroethylene emulsion is 40-80 wt%;

the mixing mode is magnetic stirring or mechanical stirring.

7. The method for preparing a micro-nano porous light trapping structure according to claim 6, wherein in the step (1-1):

the alkyl amine oxide surfactant is selected from octadecyl dihydroxyethyl amine oxide, hexadecyl dihydroxyethyl amine oxide, tetradecyl dihydroxyethyl amine oxide, dodecyl dihydroxyethyl amine oxide, hexadecyl dimethyl amine oxide, octadecyl dimethyl amine oxide, dodecyl dimethyl amine oxide, tetradecyl dimethyl amine oxide, octadecyl amidopropyl amine oxide, cocamidopropyl amine oxide or lauramidopropyl amine oxide.

8. The method for preparing a micro-nano porous light trapping structure according to claim 3, characterized in that,

in the step (2-1):

the polytetrafluoroethylene polymer template is a polytetrafluoroethylene plate or a polytetrafluoroethylene film;

the soaking time is 5-30 minutes;

the drying temperature is 90-120 ℃.

In the step (2-2):

the heat treatment temperature is 320-360 ℃, and the heat treatment time is 5-20 minutes;

the slow cooling process comprises the following steps: starting from the heat treatment temperature of claim 12, the temperature is decreased to 200 ℃ at a cooling rate of 1 ± 0.5 ℃/min, and then the temperature is naturally cooled to room temperature.

9. The preparation method of the micro-nano porous light trapping structure according to claim 4, characterized by comprising the following steps: in the step (3), the concentration of the hydrofluoric acid is 10-20%, and the etching time is 1-24 hours.

10. The micro-nano porous light trapping structure obtained by the method according to any one of claims 1 to 9.

Technical Field

The invention relates to a light trapping structure material.

Background

The selective absorption structure is a functional optical structure capable of performing high light absorption at a specific target waveband and performing low light absorption at a non-specific target waveband, and plays an important role in scenes requiring selective absorption of light, such as radiation refrigeration, heat control, energy enrichment and the like. For example, optical structures for solar absorption require high absorptance in the visible and low absorptance and emittance in the infrared to achieve efficient solar concentration. The existing selective absorption structure is mainly prepared by means of electroplating, spraying, electrochemistry, film coating, vapor deposition and the like, can realize selective absorption of light functionally, but is difficult to accurately control the range and boundary of a target absorption waveband and a non-target absorption waveband. With the continuous development of aerospace technologies and weaponry, higher requirements are put forward on the absorption accuracy, accuracy and efficiency of selective absorption structures, and the preparation of efficient absorption structures with accurately adjustable absorption bands needs further exploration.

Disclosure of Invention

The invention aims to provide a preparation method of a micro-nano porous light trapping structure, which is characterized by comprising the following steps of:

(1) preparing micron or nano inorganic particles as a pore-foaming agent;

(2) dispersing and embedding inorganic particles on the surface of a polymer template;

(3) and after inorganic particles are removed by etching, a porous light trapping structure is formed on the surface of the polymer template.

Further, the step (1) comprises the following steps:

(1-1) preparation of inorganic particle Dispersion: mixing and grinding inorganic particle silicon dioxide, deionized water, a surfactant and an alkaline stabilizer to prepare silicon dioxide dispersion liquid;

wherein, the mixture ratio of each component is as follows:

100 portions of silicon dioxide

8000 portions and 9900 portions of deionized water

2-500 parts of nonionic surfactant

1-500 parts (1-2) of an alkaline stabilizer, and the preparation of the impregnating solution: mixing the silicon dioxide dispersion liquid with the polytetrafluoroethylene emulsion to prepare a soaking liquid;

wherein, the mixture ratio of each component is as follows:

10-99 parts of silicon dioxide dispersion liquid

2-90 parts of polytetrafluoroethylene emulsion

2-80 parts of impregnating solution.

Further, the step (2) comprises the following steps:

(2-1) soaking of the polymer template:

cleaning the surface of a polytetrafluoroethylene high-molecular template, immersing the template into the impregnating solution obtained in the step (1-2), and drying to obtain coupled particles of silicon dioxide and polytetrafluoroethylene distributed on the surface of the template;

(2-2) particle intercalation:

and (3) carrying out heat treatment on the polytetrafluoroethylene polymer template treated in the step (2-1) to embed the coupling particles into the surface layer of the template, and then slowly cooling the template to room temperature.

Further, in the step (3), the surface of the template obtained by the treatment in the step (2-2) is etched by hydrofluoric acid, and is ultrasonically cleaned by deionized water or ethanol solution, and then is dried to obtain the porous structure.

Further, in the step (1-1):

the inorganic particles are nano or micron-sized silica particles with standard sizes;

the grinding mode is a sand grinding method or a ball grinding method;

the surfactant is a nonionic surfactant or an amphoteric surfactant which is nonionic under alkaline conditions;

the alkaline stabilizer is metal hydroxide;

the pH of the dispersion was 7-9.

Further, in the step (1-1):

the grain size of the nano-scale silicon dioxide is 100-950nm, and the grain size of the micro-scale silicon dioxide is 1-30 μm;

in the grinding mode, the grinding time of the sand grinding method is 1-5 hours. Grinding for 3-20 hours by a ball milling method;

the nonionic surfactant is selected from polyethylene glycol octyl phenyl ether and alkylphenol polyoxyethylene ether;

the amphoteric surfactant which is nonionic under alkaline condition is alkyl amine oxide surfactant;

the metal hydroxide is selected from aluminum hydroxide or copper hydroxide;

further, in the step (1-2):

the solid content of the polytetrafluoroethylene emulsion is 40-80 wt%;

the mixing mode is magnetic stirring or mechanical stirring.

Further, in the step (1-1):

the alkyl amine oxide surfactant is selected from octadecyl dihydroxyethyl amine oxide, hexadecyl dihydroxyethyl amine oxide, tetradecyl dihydroxyethyl amine oxide, dodecyl dihydroxyethyl amine oxide, hexadecyl dimethyl amine oxide, octadecyl dimethyl amine oxide, dodecyl dimethyl amine oxide, tetradecyl dimethyl amine oxide, octadecyl amidopropyl amine oxide, cocamidopropyl amine oxide or lauramidopropyl amine oxide;

further, in the step (2-1):

the polytetrafluoroethylene polymer template is a polytetrafluoroethylene plate or a polytetrafluoroethylene film;

the soaking time is 5-30 minutes;

the drying temperature is 90-120 ℃.

Further, in the step (2-2):

the heat treatment temperature is 320-360 ℃, and the heat treatment time is 5-20 minutes;

the slow cooling process comprises the following steps: starting from the heat treatment temperature of claim 12, the temperature is decreased to 200 ℃ at a cooling rate of 1 ± 0.5 ℃/min, and then the temperature is naturally cooled to room temperature.

Further, in the step (3), the concentration of hydrofluoric acid is 10-20%, and the etching time is 1-24 hours.

The invention claims a micro-nano porous light trapping structure obtained according to the method.

The method has the benefits that the optical absorption structure with uniform size and high precision is constructed by selecting the pore-foaming agent with the particle size matched with the wavelength of the target absorption light source, so that the directional high-efficiency absorption of light is realized. In addition, the size adjustable range of the optical absorption structure is 0.1-30 microns, selective absorption of a specific light source in the range from a vacuum ultraviolet band to a far infrared band can be met, and the application range and the application scene of the structure are greatly expanded.

Drawings

FIG. 1 is a schematic diagram of a micro-nano porous light trapping structure according to the present invention.

Detailed Description

The present invention is further illustrated by the following examples, but it should not be construed that the scope of the above-described subject matter is limited to the following examples. Various substitutions and alterations can be made without departing from the technical idea of the invention and the scope of the invention is covered by the present invention according to the common technical knowledge and the conventional means in the field.

Example 1:

the preparation method of the micro-nano porous light trapping structure comprises the following steps:

(1) preparing micron or nano inorganic particles as pore-foaming agent:

(1-1) preparation of inorganic particle Dispersion: weighing the following raw materials in parts by weight: 10g of silicon dioxide particles with the particle size of 200nm, 90g of deionized water, 2g of surfactant alkylphenol polyoxyethylene, and 1g of alkaline stabilizer aluminum hydroxide; mixing and grinding for 5 hours by a sand grinding method to prepare a silicon dioxide dispersion liquid, wherein the pH value of the dispersion liquid is 8.

(1-2) preparation of immersion liquid:

weighing the following raw materials in parts by weight: 50g of silicon dioxide dispersion liquid and 20g of polytetrafluoroethylene emulsion with solid content of 50% in the step (1-1); the impregnating solution is prepared by mixing and stirring by magnetic force, and the concentration of the impregnating solution is 30%.

(2) Dispersing and embedding inorganic particles on the surface of a polymer template (2-1), soaking the polymer template:

and (2) cleaning the surface of the template of the polytetrafluoroethylene plate, soaking the template of the polytetrafluoroethylene plate into the soaking liquid in the step (1), taking out the template of the polytetrafluoroethylene plate after soaking for 15 minutes, placing the template of the polytetrafluoroethylene plate into a drying oven at 100 ℃, and completely drying the template of the polytetrafluoroethylene plate, wherein coupling particles of silicon dioxide and polytetrafluoroethylene are distributed on the surface of the template.

(2-2) particle intercalation:

and (3) carrying out heat treatment on the polytetrafluoroethylene polymer template obtained in the step (2-1) at 340 ℃ for 10 minutes to embed the coupling particles into the surface layer of the template, cooling to 200 ℃ at a cooling speed of 1 +/-0.5 ℃/min, and then naturally cooling the template to room temperature along with the furnace.

(3) Etching the template:

and (3) etching the surface of the template obtained in the step (2) for 12 hours by using hydrofluoric acid with the concentration of 20%, then ultrasonically cleaning the surface by using deionized water or ethanol solution, and drying to obtain the porous light trapping structure.

The diameter of a hole in the light trapping structure is 200 +/-20 nm, the light trapping structure is used for directional absorption of light in vacuum ultraviolet bands, and the directional absorption rate is improved by 16.5%.

Example 2:

the preparation method of the micro-nano porous light trapping structure comprises the following steps:

(1) preparing micron or nano inorganic particles as pore-foaming agent:

(1-1) weighing the following raw materials by weight: 10g of silicon dioxide particles with the particle size of 400nm, 90g of deionized water, 1.5g of surfactant alkylphenol polyoxyethylene, and 0.8g of alkaline stabilizer aluminum hydroxide; mixing and grinding for 4 hours by a sand milling method to prepare a silicon dioxide dispersion liquid, wherein the pH value of the dispersion liquid is 8.

(1-2) preparation of immersion liquid:

weighing the following raw materials in parts by weight: 50g of silicon dioxide dispersion liquid and 20g of polytetrafluoroethylene emulsion with solid content of 50% in the step (1-1); the impregnating solution is prepared by mixing and stirring by magnetic force, and the concentration of the impregnating solution is 30%.

(2) Dispersing and embedding inorganic particles on the surface of a polymer template (2-1), soaking the polymer template:

and (2) cleaning the surface of the template of the polytetrafluoroethylene plate, soaking the template of the polytetrafluoroethylene plate into the soaking liquid in the step (1), taking out the template of the polytetrafluoroethylene plate after soaking for 15 minutes, placing the template of the polytetrafluoroethylene plate into a drying oven at 100 ℃, and completely drying the template of the polytetrafluoroethylene plate, wherein coupling particles of silicon dioxide and polytetrafluoroethylene are distributed on the surface of the template.

(2-2) particle intercalation:

and (3) carrying out heat treatment on the polytetrafluoroethylene polymer template obtained in the step (2-1) at 340 ℃ for 10 minutes to embed the coupling particles into the surface layer of the template, cooling to 200 ℃ at a cooling speed of 1 +/-0.5 ℃/min, and then naturally cooling the template to room temperature along with the furnace.

(3) Etching the template:

and (3) etching the surface of the template obtained in the step (2) for 12 hours by using hydrofluoric acid with the concentration of 20%, then ultrasonically cleaning the surface by using deionized water or ethanol solution, and drying to obtain the porous light trapping structure.

The diameter of a hole in the light trapping structure is 400 +/-40 nm, the light trapping structure is used for directional absorption of ultraviolet band light, and the directional absorption rate is improved by 15.3%.

Example 3:

the preparation method of the micro-nano porous light trapping structure comprises the following steps:

(1) preparing micron or nano inorganic particles as pore-foaming agent:

(1-1) preparation of inorganic particle Dispersion:

weighing the following raw materials in parts by weight: 10g of silicon dioxide particles with the particle size of 800nm, 90g of deionized water, 1g of surfactant alkylphenol polyoxyethylene, and 0.5g of alkaline stabilizer aluminum hydroxide; mixing and grinding for 3 hours by a sand grinding method to prepare a silicon dioxide dispersion liquid, wherein the pH value of the dispersion liquid is 8.

(1-2) preparation of immersion liquid:

weighing the following raw materials in parts by weight: 50g of silicon dioxide dispersion liquid and 20g of polytetrafluoroethylene emulsion with solid content of 50% in the step (1-1); the impregnating solution is prepared by mixing and stirring by magnetic force, and the concentration of the impregnating solution is 30%.

(2) Dispersing and embedding inorganic particles on the surface of a polymer template (2-1), soaking the polymer template:

and (2) cleaning the surface of the template of the polytetrafluoroethylene plate, soaking the template of the polytetrafluoroethylene plate into the soaking liquid in the step (1), taking out the template of the polytetrafluoroethylene plate after soaking for 15 minutes, placing the template of the polytetrafluoroethylene plate into a drying oven at 100 ℃, and completely drying the template of the polytetrafluoroethylene plate, wherein coupling particles of silicon dioxide and polytetrafluoroethylene are distributed on the surface of the template.

(2-2) particle intercalation:

and (3) carrying out heat treatment on the polytetrafluoroethylene polymer template obtained in the step (2-1) at 340 ℃ for 10 minutes to embed the coupling particles into the surface layer of the template, cooling to 200 ℃ at a cooling speed of 1 +/-0.5 ℃/min, and then naturally cooling the template to room temperature along with the furnace.

(3) Etching the template:

and (3) etching the surface of the template obtained in the step (2) for 12 hours by using hydrofluoric acid with the concentration of 20%, then ultrasonically cleaning the surface by using deionized water or ethanol solution, and drying to obtain the porous light trapping structure.

The diameter of a hole in the light trapping structure is 800 +/-80 nm, the light trapping structure is used for directional absorption of visible light band light, and the directional absorption rate is improved by 14.1%.

Example 4:

the preparation method of the micro-nano porous light trapping structure comprises the following steps:

(1) preparing micron or nano inorganic particles as pore-foaming agent:

(1-1) preparation of inorganic particle Dispersion:

weighing the following raw materials in parts by weight: 10g of silicon dioxide particles with the particle size of 2.5 mu m, 90g of deionized water, 2g of surfactant polyethylene glycol octyl phenyl ether and 1g of alkaline stabilizer aluminum hydroxide; mixing and grinding for 12 hours by adopting a ball milling method to prepare a silicon dioxide dispersion liquid, wherein the pH value of the dispersion liquid is 8.

(1-2) preparation of immersion liquid:

weighing the following raw materials in parts by weight: 50g of silicon dioxide dispersion liquid and 20g of polytetrafluoroethylene emulsion with solid content of 50% in the step (1-1); the impregnating solution is prepared by mixing and stirring by magnetic force, and the concentration of the impregnating solution is 30%.

(2) Dispersing and embedding inorganic particles on the surface of a polymer template (2-1), soaking the polymer template:

and (2) cleaning the surface of the template of the polytetrafluoroethylene plate, soaking the template of the polytetrafluoroethylene plate into the soaking liquid in the step (1), taking out the template of the polytetrafluoroethylene plate after soaking for 15 minutes, placing the template of the polytetrafluoroethylene plate into a drying oven at 100 ℃, and completely drying the template of the polytetrafluoroethylene plate, wherein coupling particles of silicon dioxide and polytetrafluoroethylene are distributed on the surface of the template.

(2-2) particle intercalation:

and (3) carrying out heat treatment on the polytetrafluoroethylene polymer template obtained in the step (2-1) at 350 ℃ for 15 minutes to embed the coupling particles into the surface layer of the template, cooling to 200 ℃ at a cooling speed of 1 +/-0.5 ℃/min, and then naturally cooling the template to room temperature along with the furnace.

(3) Etching the template:

and (3) etching the surface of the template obtained in the step (2) for 12 hours by using hydrofluoric acid with the concentration of 20%, then ultrasonically cleaning the surface by using deionized water or ethanol solution, and drying to obtain the porous light trapping structure.

The diameter of a hole in the light trapping structure is 2.5 +/-0.25 mu m, the light trapping structure is used for directional absorption of near-infrared band light, and the directional absorption rate is improved by 17.9%.

Example 5:

the preparation method of the micro-nano porous light trapping structure comprises the following steps:

(1) preparing micron or nano inorganic particles as pore-foaming agent:

(1-1) preparation of inorganic particle Dispersion:

weighing the following raw materials in parts by weight: 10g of silicon dioxide particles with the particle size of 5 mu m, 90g of deionized water, 1.5g of surfactant polyethylene glycol octyl phenyl ether and 0.8g of alkaline stabilizer aluminum hydroxide; mixing and grinding for 8 hours by adopting a ball milling method to prepare a silicon dioxide dispersion liquid, wherein the pH value of the dispersion liquid is 8.

(1-2) preparation of immersion liquid:

weighing the following raw materials in parts by weight: 50g of silicon dioxide dispersion liquid and 20g of polytetrafluoroethylene emulsion with solid content of 50% in the step (1-1); the impregnating solution is prepared by mixing and stirring by magnetic force, and the concentration of the impregnating solution is 30%.

(2) Dispersing and embedding inorganic particles on the surface of a polymer template (2-1), soaking the polymer template:

and (2) cleaning the surface of the template of the polytetrafluoroethylene plate, soaking the template of the polytetrafluoroethylene plate into the soaking liquid in the step (1), taking out the template of the polytetrafluoroethylene plate after soaking for 15 minutes, placing the template of the polytetrafluoroethylene plate into a drying oven at 100 ℃, and completely drying the template of the polytetrafluoroethylene plate, wherein coupling particles of silicon dioxide and polytetrafluoroethylene are distributed on the surface of the template.

(2-2) particle intercalation:

and (3) carrying out heat treatment on the polytetrafluoroethylene polymer template obtained in the step (2-1) at 350 ℃ for 15 minutes to embed the coupling particles into the surface layer of the template, cooling to 200 ℃ at a cooling speed of 1 +/-0.5 ℃/min, and then naturally cooling the template to room temperature along with the furnace.

(3) Etching the template:

and (3) etching the surface of the template obtained in the step (2) for 12 hours by using hydrofluoric acid with the concentration of 20%, then ultrasonically cleaning the surface by using deionized water or ethanol solution, and drying to obtain the porous light trapping structure.

The diameter of a hole in the light trapping structure is 5 +/-0.5 mu m, the light trapping structure is used for directional absorption of light in a middle infrared band, and the directional absorption rate is improved by 19.5%.

Example 6:

the preparation method of the micro-nano porous light trapping structure comprises the following steps:

(1) preparing micron or nano inorganic particles as pore-foaming agent:

(1-1) preparation of inorganic particle Dispersion:

weighing the following raw materials in parts by weight: 10g of silicon dioxide particles with the particle size of 14 mu m, 90g of deionized water, 1g of surfactant polyethylene glycol octyl phenyl ether and 0.5g of alkaline stabilizer aluminum hydroxide; the silica dispersion was prepared by mixing and milling for 4 hours by ball milling, the pH of the dispersion being 8.

(1-2) preparation of immersion liquid:

weighing the following raw materials in parts by weight: 50g of silicon dioxide dispersion liquid and 20g of polytetrafluoroethylene emulsion with solid content of 50% in the step (1-1); the impregnating solution is prepared by mixing and stirring by magnetic force, and the concentration of the impregnating solution is 30%.

(2) Dispersing and embedding inorganic particles on the surface of a polymer template (2-1), soaking the polymer template:

and (2) cleaning the surface of the template of the polytetrafluoroethylene plate, soaking the template of the polytetrafluoroethylene plate into the soaking liquid in the step (1), taking out the template of the polytetrafluoroethylene plate after soaking for 15 minutes, placing the template of the polytetrafluoroethylene plate into a drying oven at 100 ℃, and completely drying the template of the polytetrafluoroethylene plate, wherein coupling particles of silicon dioxide and polytetrafluoroethylene are distributed on the surface of the template.

(2-2) particle intercalation:

and (3) carrying out heat treatment on the polytetrafluoroethylene polymer template obtained in the step (2-1) at 350 ℃ for 20 minutes to embed the coupling particles into the surface layer of the template, cooling to 200 ℃ at a cooling speed of 1 +/-0.5 ℃/min, and then naturally cooling the template to room temperature along with the furnace.

(3) Etching the template:

and (3) etching the surface of the template obtained in the step (2) for 12 hours by using hydrofluoric acid with the concentration of 20%, then ultrasonically cleaning the surface by using deionized water or ethanol solution, and drying to obtain the porous light trapping structure.

The diameter of the hole in the light trapping structure is 14 +/-1.4 microns, the light trapping structure is used for directional absorption of far infrared band light, and the directional absorption rate is improved by 21.3%.