Manufacturing method of light trapping microstructure with large depth-to-width ratio

Abstract

The invention discloses a manufacturing method of a light trapping microstructure with a large depth-to-width ratio, and aims to solve the problem that the light trapping microstructure with a large size and a large depth-to-width ratio is difficult to form in a large-area, high-quality, high-efficiency and low-cost manner, and an ultraviolet curing impressing forming method of the light trapping microstructure with the large depth-to-width ratio is invented. The problem that mold filling and demolding are difficult during imprinting of the large-size and large-depth-to-width-ratio light trapping microstructure is explored, and the low-cost, large-area and high-efficiency preparation technology of the large-depth-to-width-ratio light trapping microstructure is provided. Test results show that during large-area forming, the surface is basically free of defects, the microstructure is basically free of damage, and the complex system is extremely high.

Description

Technical Field

[0001] The present invention belongs to the field of metamaterial preparation, and in particular relates to a method for manufacturing a light-trapping microstructure with a large aspect ratio. Background Art

[0002] With technological advancements and increasing demand for new energy sources, efficient and stable photovoltaic devices and optical sensors have garnered widespread attention. Light-trapping microstructures, a key branch of metamaterials, achieve ultra-broadband light absorption through subwavelength structural design. Their core principle is to utilize periodic nanostructures to manipulate light propagation paths, combined with the local field enhancement effect, to break through the optical limits of traditional materials.

[0003] The design of light-trapping microstructures can significantly improve the light capture efficiency of devices, showing great application potential in the fields of photovoltaics and flexible electronics. Currently, the main methods for manufacturing light-trapping microstructure arrays are: photolithography, electron beam etching, laser processing technology, and diamond fly-cutting technology. Photolithography forms high-precision micro-nanostructures on the surface of a substrate through mask exposure and chemical etching processes, and is one of the core methods for preparing periodic light-trapping structures; electron beam etching uses high-energy electron beams to directly draw patterns on photoresist, with a resolution of nanometers (<10nm), which is suitable for the preparation of complex non-periodic structures; laser processing uses femtosecond or nanosecond lasers to ablate or modify the surface of materials, and has the characteristics of no need for masks and high flexibility; diamond fly-cutting is an ultra-precision machining technology that uses single-crystal diamond tools to perform micron-level cutting of hard and brittle materials. It is suitable for the direct forming of high-precision optical components. Its core advantages lie in low surface roughness (<10nm) and high geometric accuracy, but equipment cost and processing efficiency still need to be optimized. Although these methods can form light-trapping microstructures, they all have problems with complex manufacturing processes, high costs, and low efficiency, which make them difficult to mass-produce. Summary of the Invention

[0004] The present invention proposes a method for manufacturing a light-trapping microstructure with a large aspect ratio, which solves the problem that the current large aspect ratio light-trapping microstructure manufacturing process is complex, costly, and inefficient, making it difficult to mass-produce.

[0005] The technical solution to achieve the present invention is: a method for fabricating a light-trapping microstructure with a large aspect ratio, comprising the following steps;

[0006] Step 1: Process a large aspect ratio light trapping microstructure master, and then proceed to step 2.

[0007] Step 2: Use the large aspect ratio light trapping microstructure master to form a concave mold, treat the surface of the concave mold, and soak it in anti-viscosity liquid, then go to step 3.

[0008] Step 3: Use the concave mold soaked in the anti-mucus liquid in step 2 as an imprint template, drip resin on the upper surface of the concave mold under vacuum, and proceed to step 4.

[0009] Step 4: Heat the resin, cover the resin with a substrate and apply pressure to solidify the resin to obtain a solidified microstructure plate, separate the solidified microstructure plate from the concave mold, and proceed to step 5.

[0010] Step 5: The solidified microstructure plate is flattened with an aluminum block and subjected to heat treatment to obtain a formed light-trapping microstructure with a large aspect ratio, which is then observed using a scanning electron microscope (SEM).

[0011] Compared with the prior art, the present invention has the following significant advantages:

[0012] (1) The formed concave mold can be reused more than 10 times after the anti-sticking treatment, which greatly improves the molding efficiency.

[0013] (2) The process of forming a light-trapping microstructure with a large aspect ratio is simple and has high precision. The surface roughness of the light-trapping microstructure with a large aspect ratio (the aspect ratio of the micro-pyramid structure is greater than 3) is less than Ra3.2.

[0014] (3) The cost is also very low while meeting the requirements for large-area molding of light-trapping microstructures with a large aspect ratio. The cost of molding a light-trapping microstructure with a large aspect ratio of 100mm×100mm is no more than 3,000 yuan. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a process flow chart of a method for fabricating a light-trapping microstructure with a large aspect ratio provided by an example of the present invention.

[0016] Figure 2 Schematic diagram of a light-trapping microstructure with a large aspect ratio formed as an example of the invention.

[0017] Figure 3 This is a front view of a replica structure of a method for fabricating a light-trapping microstructure with a large aspect ratio provided by an example of the present invention. DETAILED DESCRIPTION

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments 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 creative work are within the scope of protection of the present invention.

[0019] The technical solutions between the various embodiments of the present invention can be combined with each other, but they must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0020] The following will further introduce the specific implementation methods, as well as the technical difficulties and inventive points of this invention in combination with this design example.

[0021] Combine Figure 1 The present invention proposes for the first time a method for fabricating a light-trapping microstructure with a large aspect ratio, which uses resin curing to achieve large-area, high-efficiency, low-cost, and high-precision molding of the light-trapping microstructure with a large aspect ratio, including the following steps:

[0022] Step 1: Process a large aspect ratio light trapping microstructure master.

[0023] The surface feature of the large aspect ratio light-trapping microstructure master is a micro-pyramid array, and the base material is aluminum alloy, stainless steel or silicon.

[0024] The micro-pyramid array is composed of a number of micro-pyramid structures arranged in rows and columns. The aspect ratio of the micro-pyramid structure is greater than 3, the height of the micro-pyramid structure is between 100-1000um, and the distance between two adjacent micro-pyramid structures is between 0-20um. Figure 2 .

[0025] The present invention proposes for the first time the formation of a micro-pyramid structure with an aspect ratio greater than 3. The innovation of the present invention lies in the use of a special technology to form a micro-pyramid structure with an aspect ratio greater than 3 over a large area, with high efficiency, low cost and high precision.

[0026] Go to step 2.

[0027] Step 2: Use the large aspect ratio light trapping microstructure master to form a concave mold, treat the surface of the concave mold, and then soak it in anti-viscosity liquid.

[0028] The concave mold material is one of acrylate, polydimethylsiloxane, and ultraviolet curing-polydimethylsiloxane.

[0029] The concave mold forming method adopts one of heat curing imprinting, ultraviolet curing imprinting and injection molding.

[0030] When treating the surface of the concave mold, it is required to reduce the contact angle of the concave mold surface to no more than 50°.

[0031] Soak the surface treated concave mold in the anti-adhesive solution to ensure that the anti-adhesive solution can adhere to the surface.

[0032] Go to step 3.

[0033] Step 3: Use the concave mold soaked in the anti-mucus liquid in step 2 as an imprint template, and drip resin on the upper surface of the concave mold under vacuum.

[0034] Step 31: Use the concave mold soaked in the anti-slime solution in step 2 as an imprint template.

[0035] Step 32: Place the concave mold serving as the imprint template into the vacuum chamber and evacuate the vacuum chamber.

[0036] When evacuating the vacuum chamber, the air pressure in the vacuum chamber needs to be reduced to below 200 Pa, and it is ensured that glue can be dispensed normally under this air pressure.

[0037] Step 33: Under vacuum, drip resin onto the upper surface of the concave mold, ensuring that the upper surface is full, that is, there is no air remaining inside the concave mold.

[0038] The present invention proposes for the first time that resin is dripped onto the upper surface of a concave mold under vacuum, so that a light-trapping microstructure with a large aspect ratio is formed without generating bubble defects.

[0039] Go to step 4.

[0040] Step 4: Heat the resin, cover the resin with a substrate and apply pressure to solidify the resin to obtain a solidified microstructure plate, and separate the solidified microstructure plate from the concave mold.

[0041] Step 41: Heat the resin and control the heating temperature so that the viscosity of the resin is the lowest when it is pressurized and filled.

[0042] Step 411: Obtain a viscosity variation curve of the resin at different temperatures through experiments, and determine a temperature range that can make the resin viscosity at the lowest position based on the viscosity variation curve.

[0043] Step 42: Place a substrate on the upper surface of the resin and apply pressure to the substrate. The amount of pressure applied and the duration of the pressure application can allow the resin to fill the concave mold as much as possible.

[0044] Step 421: Covering the upper surface of the resin with a substrate, wherein the substrate material is one of glass, polymethyl methacrylate, and polyethylene terephthalate.

[0045] Step 422: applying pressure to the substrate on the upper surface of the resin, using a pressing device such as plate pressing, air pressing, or roller pressing.

[0046] Step 43: Adjust the curing parameters so that the resin can be completely cured to obtain a cured microstructure plate. The resin curing method is one of thermal curing, ultraviolet curing, and room temperature curing.

[0047] Step 44: Separate the cured microstructure plate from the concave mold without damaging the microstructure.

[0048] Go to step 5.

[0049] Step 5: Flatten the solidified microstructure plate with an aluminum block and perform heat treatment to obtain a formed light-trapping microstructure with a large aspect ratio, and observe it with a SEM scanning electron microscope, as shown in the following figure: Figure 3 .

[0050] Step 51: Flatten the surface of the solidified microstructure plate with an aluminum block, without damaging the surface microstructure.

[0051] Step 52: heat-treating the flattened microstructure plate to ensure that there is no warping of the microstructure plate after the heat treatment, thereby obtaining a formed light-trapping microstructure with a large aspect ratio.

[0052] Step 53: The formed light-trapping microstructure with a large aspect ratio is observed using a SEM scanning electron microscope to obtain a surface pyramid structure diagram, such as Figure 3 .

Claims

1. A method for fabricating a light-trapping microstructure with a large aspect ratio, characterized in that: The steps are as follows; Step 1: Process a large aspect ratio light trapping microstructure master, and then proceed to step 2; Step 2: Using the aforementioned high aspect ratio light trapping microstructure master to form a concave mold, the surface of the concave mold is treated and then immersed in an anti-viscosity solution, and then proceeding to step 3; Step 3: Use the concave mold soaked in the anti-sliming liquid in step 2 as an imprint template, drip resin on the upper surface of the concave mold under vacuum, and proceed to step 4; Step 4: Heat the resin, cover the substrate on the resin and apply pressure to solidify the resin to obtain a solidified microstructure plate, separate the solidified microstructure plate from the concave mold, and proceed to step 5; Step 5: The solidified microstructure plate is flattened with an aluminum block and subjected to heat treatment to obtain a formed light-trapping microstructure with a large aspect ratio, which is then observed using a scanning electron microscope (SEM).

2. The method for fabricating a light-trapping microstructure with a large aspect ratio according to claim 1, wherein: In step 1, a large aspect ratio light trapping microstructure master is processed as follows: The surface feature of the large aspect ratio light trapping microstructure master is a micro-pyramid array, and the base material is aluminum alloy, stainless steel or silicon; The micro-pyramid array is composed of a plurality of micro-pyramid structures arranged in rows and columns. The aspect ratio of the micro-pyramid structure is greater than 3, the height of the micro-pyramid structure is between 100-1000 μm, and the distance between two adjacent micro-pyramid structures is between 0-50 μm.

3. The method for fabricating a light-trapping microstructure with a large aspect ratio according to claim 2, wherein: In step 2, the large aspect ratio light trapping microstructure master is used to form a concave mold, and the surface of the concave mold is treated and then immersed in an anti-viscosity solution, as follows: The concave mold material is one of acrylate, polydimethylsiloxane, and UV-curable polydimethylsiloxane; The concave mold forming method adopts one of heat curing imprinting, ultraviolet curing imprinting and injection molding; When treating the surface of the concave mold, it is required to reduce the contact angle of the concave mold surface to no more than 50°; Soak the surface treated concave mold in the anti-adhesive solution to ensure that the anti-adhesive solution can adhere to the surface.

4. The method for fabricating a light-trapping microstructure with a large aspect ratio according to claim 1, wherein: In step 3, the concave mold soaked in the anti-slime solution in step 2 is used as an imprint template, and resin is dripped onto the upper surface of the concave mold under vacuum, as follows: Step 31: Using the concave mold soaked in the anti-slime solution in step 2 as an imprint template; Step 32: Place the concave mold serving as the imprint template into a vacuum chamber and evacuate the vacuum chamber; Step 33: Under vacuum, drip resin onto the upper surface of the concave mold, ensuring that the upper surface is full, that is, there is no air remaining inside the concave mold.

5. The method for fabricating a light-trapping microstructure with a large aspect ratio according to claim 4, wherein: In step 32, the concave mold serving as the imprint template is placed in a vacuum chamber, and the vacuum chamber is evacuated as follows: When evacuating the vacuum chamber, the air pressure in the vacuum chamber needs to be reduced to below 200 Pa, and it is ensured that glue can be dispensed normally under this air pressure.

6. The method for fabricating a light-trapping microstructure with a large aspect ratio according to claim 1, wherein: In step 4, the resin is heated, a substrate is covered on the resin, and pressure is applied to solidify the resin to obtain a solidified microstructured plate, and the solidified microstructured plate is separated from the concave mold as follows: Step 41: Heat the resin and control the heating temperature so that the viscosity of the resin is the lowest when it is pressurized and filled; Step 42: Place a substrate on the upper surface of the resin and apply pressure to the substrate. The pressure applied should be large enough and last for a long time to allow the resin to fill the concave mold as much as possible. Step 43: Adjusting curing parameters to allow the resin to be completely cured to obtain a cured microstructured plate; Step 44: Separate the cured microstructure plate from the concave mold without damaging the microstructure.

7. The method for fabricating a light-trapping microstructure with a large aspect ratio according to claim 6, wherein: In step 41, the resin is heated to achieve the lowest viscosity when the resin is pressurized and filled, as follows: The viscosity variation curve of the resin at different temperatures is obtained through experiments, and the temperature range in which the viscosity of the resin is at the lowest position is determined based on the above viscosity variation curve.

8. The method for fabricating a light-trapping microstructure with a large aspect ratio according to claim 6, wherein: In step 42, a substrate is placed on the upper surface of the resin and pressure is applied to the substrate. The amount of pressure applied and the duration of the pressure are such that the resin fills the concave mold as much as possible, as follows: Step 421: Covering the upper surface of the resin with a substrate, wherein the substrate material is one of glass, polymethyl methacrylate, and polyethylene terephthalate; Step 422: applying pressure to the substrate on the upper surface of the resin, using a pressing device such as plate pressing, air pressing, or roller pressing.

9. The method for fabricating a light-trapping microstructure with a large aspect ratio according to claim 6, wherein: In step 43 , the resin is cured by one of thermal curing, ultraviolet curing, and room temperature curing.

10. The method for fabricating a light-trapping microstructure with a large aspect ratio according to claim 1, wherein: In step 5, the cured microstructure plate is flattened with an aluminum block and heat treated to obtain a formed light-trapping microstructure with a large aspect ratio, which is then observed using a scanning electron microscope (SEM), as follows: Step 51: Flatten the surface of the cured microstructured plate with an aluminum block, without damaging the surface microstructure. Step 52: heat-treating the flattened microstructure plate to ensure that the microstructure plate is free of warping after the heat treatment, thereby obtaining a formed light-trapping microstructure with a large aspect ratio; Step 53: The formed light-trapping microstructure with a large aspect ratio is observed using a SEM scanning electron microscope to obtain a surface pyramid structure diagram.

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