A double slope pyramid structure monocrystalline silicon and preparation method and application thereof

Abstract

The application discloses a kind of double slope pyramid structure monocrystalline silicon and its preparation method and application.This double slope structure has two slope values compared with conventional pyramid structure, there are multiple layers of wrinkles on the first slope pyramid surface, and there are also multiple layers of wrinkles on the second slope pyramid surface, the double slope pyramid structure with multiple layers of wrinkles obtains lower reflectivity, to achieve low reflection suede structure, a two-step texturing method is proposed to obtain the double slope and multiple layers of wrinkles pyramid structure, the reflectivity can be reduced to 7-8.5%, and the photoelectric conversion efficiency of solar cell is improved.

Description

Technical Field

[0001] This invention relates to the field of crystalline silicon solar cell manufacturing technology, specifically a double-slope pyramid structure monocrystalline silicon, its preparation method, and its application. Background Technology

[0002] Solar photovoltaic (PV) equipment is a crucial component of clean energy and a key area of ​​global development. With advancements in PV technology and declining costs, PV power generation has become one of the most competitive forms of clean energy. Currently, mainstream PV modules on the market have stricter requirements for photoelectric conversion efficiency, making it extremely important to further increase their efficiency. A core technical indicator for solar cells lies in the superior light-trapping effect of the etched textured surface. The light-trapping effect in monocrystalline silicon refers to the formation of specific textured structures, such as pyramids, on the surface of monocrystalline silicon wafers. This causes incident light to bounce repeatedly within the wafer, significantly improving light capture efficiency, reducing surface reflectivity, increasing the generation of photogenerated carriers, and enhancing cell conversion efficiency. Currently, the morphology of monocrystalline silicon surfaces after mainstream wet texturing is still predominantly pyramidal, with reflectivity around 9-11%. To overcome this performance bottleneck, texturing additive manufacturers are continuously optimizing the chemical composition of additives and texturing process parameters, striving to construct a more ideal microstructure on the monocrystalline silicon surface to further reduce reflectivity and improve cell efficiency.

[0003] However, existing technologies, such as patent CN202211422486, still use a single-slope pyramid structure with a simple surface structure. While this structure is effective at trapping light within a specific incident angle range, it has limited ability to suppress reflections of large-angle or non-perpendicular incident light. Summary of the Invention

[0004] To address the challenge of achieving multi-angle light capture on the surface of pyramid-structured monocrystalline silicon in existing technologies, this invention proposes a dual-slope pyramid-structured monocrystalline silicon, its fabrication method, and its applications. This invention designs a dual-slope pyramid-structured monocrystalline silicon structure. Compared to conventional pyramid structures, this dual-slope structure has two slope values: multiple layers of wrinkles on the first slope pyramid surface and multiple layers of wrinkles on the second slope pyramid surface. This pyramid structure with dual slopes and multiple layers of wrinkles achieves lower reflectivity. To achieve a low-reflectivity textured surface structure, a two-step texturing method is proposed to obtain the dual-slope and multi-layered wrinkle pyramid structure, reducing reflectivity to 7-8.5% and improving the photoelectric conversion efficiency of solar cells.

[0005] One of the technical solutions of the present invention is to provide a monocrystalline silicon with a double-slope pyramid structure. The monocrystalline silicon has a pyramid base and a pyramid apex, wherein the angle between the hypotenuse of the pyramid base and the base side is 55° to 56°, and the angle between the hypotenuse of the pyramid apex and the hypotenuse of the pyramid base is 168° to 179.8°.

[0006] The second technical solution of the present invention is to provide a method for preparing the above-mentioned double-slope pyramid structure monocrystalline silicon, wherein the monocrystalline silicon wafer is texturized in an alkaline texturing solution A in one step, and then the texturized silicon wafer is washed with water and then placed in an alkaline texturing solution B for a second step of texturing; wherein the alkaline texturing solution B includes slope control agent 1 and slope control agent 2; slope control agent 1 contains carboxylate group; slope control agent 2 contains hydroxyl group and hydrophobic terminal methyl group.

[0007] Furthermore, the slope control agent 1 is one or more of sodium lactate, sodium glycolate, sodium oxalate, and sodium tartrate. Slope control agent 1 is a small-molecule compound containing a carboxylate group. The carboxylate group forms hydrogen bonds with the Si-H bonds on the pyramid surface, adsorbing onto the silicon surface to form nucleation sites. The small molecular weight of slope control agent 1 results in a rapid desorption rate on the silicon wafer surface.

[0008] Furthermore, slope control agent 2 is one or more of sodium hydroxypropyl methylcellulose, sodium hydroxyethyl cellulose, sodium hydroxymethyl cellulose, sodium hydroxypropyl cellulose, and sodium hydroxybutyl cellulose. Slope control agent 2 is a large-molecule compound with multiple hydroxyl groups and many hydrophobic terminal methyl groups. The hydroxyl groups form hydrogen bonds with the Si-H bonds on the pyramid surface and are adsorbed at the apex of the pyramid. Due to its large molecular weight, slope control agent 2 desorbs slowly from the silicon wafer surface. The difference in reaction rate between the two slope control agents results in a dual slope value for the pyramid, with slope control agent 1 forming a larger slope value than slope control agent 2. The organic base accelerates the etching of the pyramid by slope control agents 1 and 2, forming multiple wrinkles on the pyramid surface, allowing light to refract multiple times on the pyramid surface, resulting in lower reflectivity for the single-crystal silicon.

[0009] Furthermore, the mass percentage of alkali in the A alkaline texturing solution is 0.5-2%, and the mass percentage of additives is 0.2%-0.6%; the texturing temperature for one-step texturing is 75-83℃, and the texturing time is 250s-300s.

[0010] In some embodiments, the additive used in the A alkaline texturing solution is GT01V08A produced by Zhejiang Silicon One New Energy Technology Co., Ltd.

[0011] Furthermore, the mass percentage of alkali in the B alkaline texturing solution is 0.1-3%, and the mass percentage of additives is 0.1%-0.6%; the additives include slope control agent 1, slope control agent 2, defoaming agent, organic alkali, and wetting agent; the two-step texturing temperature is 55-70℃, and the texturing time is 90s-150s.

[0012] Furthermore, the degassing agent is one or more of polyfructose, polydextrose, glycerophosphate choline-carboxymethyl-β-cyclodextrin, and konjac flour; the selected degassing agent has a multi-hydroxyl structure, which effectively reduces the interfacial tension of silicon, facilitates the removal of gas generated by silicon etching from the surface, and allows the micro-reaction in the two-step texturing tank to continue.

[0013] The organic base is one or more of sodium tert-butoxide, potassium ethoxide, and sodium methoxide; The wetting agent is one or more of sodium lauryl hydroxyethyl sulfonate, sodium hexadecyl sulfonate dioctyl succinate sodium salt, and sodium fatty acid methyl ester sulfonate.

[0014] Furthermore, the additives contain 1%-2% defoamer, 1%-5% slope control agent 1, 0.01%-0.05% slope control agent 2, 0.4%-3% organic alkali, 0.01%-2% wetting agent, and the remainder is deionized water.

[0015] Furthermore, the silicon wafers obtained after the second texturing step are washed with water and then dried at a temperature of 80-100℃ for 400-700 seconds.

[0016] In some embodiments, it can be prepared by the following steps: 1. One-step texturing: In a one-step texturing tank, alkali, texturing additives, and water are mixed evenly to form the first-step texturing solution. A monocrystalline silicon wafer is inserted into a basket and placed into the one-step texturing tank for etching to form a pyramid structure. The mass percentage of alkali in the one-step texturing tank is 0.5-2%, and the mass percentage of additives is 0.2%-0.6%. The texturing temperature is 75-83℃, and the texturing time is 250-300 seconds. The alkali is one or both of potassium hydroxide and sodium hydroxide; the texturing additive is a conventional texturing additive; and the water is deionized water.

[0017] 2. Water washing: The silicon wafers after one-step texturing are washed in a room temperature deionized water bath for 100s-150s.

[0018] 3. Two-step texturing: Place the sheets cleaned in step 2 into a two-step texturing bath for texturing. The texturing temperature is 55-70℃, and the texturing time is 90s-150s. The mass percentage of alkali in the two-step texturing bath is 0.1-3%, and the mass percentage of additives is 0.1%-0.6%. The alkali is one or both of potassium hydroxide and sodium hydroxide, and the water is deionized water.

[0019] 4. Washing and drying: After texturing in step 3, wash the wafer in a deionized water bath at room temperature for 100-150 seconds, and then put it into a drying bath to dry the silicon wafer. The drying temperature is 80-100℃ and the drying time is 400-700 seconds.

[0020] The third technical solution of the present invention is to provide the application of the above-mentioned double-slope pyramid structure monocrystalline silicon.

[0021] The beneficial effects of this invention are as follows: A pyramidal structure monocrystalline silicon with two slopes was fabricated. The pyramidal surface has a multi-fold structure, which allows light to be refracted multiple times on the pyramidal surface, resulting in lower reflectivity for the monocrystalline silicon. The average reflectivity at wavelengths of 350-1050 nm can be as low as 7-8.5%. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the dual-slope structure of the present invention.

[0023] Figure 2 This is a top-view SEM image of the pyramid-shaped surface of a silicon wafer after texturing, according to Embodiment 1 of the present invention.

[0024] Figure 3 This is a SEM cross-sectional view of the pyramid on the surface of the silicon wafer after texturing in Embodiment 1 of the present invention.

[0025] Figure 4 This is a SEM cross-sectional view of the pyramid on the surface of the silicon wafer after texturing in Example 2.

[0026] Figure 5 This is a top-view SEM image of the pyramid-shaped surface of a silicon wafer after texturing, as shown in Comparative Example 1 of this invention.

[0027] Figure 6 This is a SEM cross-sectional view of the pyramid on the surface of the silicon wafer after texturing, as shown in Comparative Example 1 of this invention.

[0028] Figure 7 This is a top-view SEM image of the pyramid-shaped surface of a silicon wafer after texturing, as shown in Comparative Example 2 of this invention.

[0029] Figure 8 This is a SEM cross-sectional view of the pyramid on the surface of the silicon wafer after texturing, as shown in Comparative Example 2 of this invention.

[0030] Figure 9 The image shows the D8 reflectance of the silicon wafers after texturing in Embodiment 1 and Comparative Examples 1 and 2 of this invention. Detailed Implementation

[0031] The following examples are provided to further illustrate the present invention and are intended to explain the invention, not to limit its scope. Unless otherwise specified, all figures are expressed in parts by weight and weight percentages.

[0032] Unless otherwise specified, the raw materials used in this invention are all conventional commercially available products; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0033] The reflectance test was performed using a D8 reflectometer to measure the reflectance values ​​in the range of 350-1050nm; the texture data test was performed by measuring the number of pyramids using Zeta 3D; and the morphology scan was performed by scanning the pyramid morphology after the two-step texturing process using SEM.

[0034] The embodiments of the present invention will be further described below with reference to several examples.

[0035] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0036] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0037] Example 1 Additive composition used in the fabrication of double-slope pyramid structured single-crystal silicon: Fructooligosaccharides: 1%, Sodium lactate: 1%, Sodium hydroxypropyl cellulose: 0.01%, Sodium methoxide: 0.4%, Sodium lauryl hydroxyethyl sulfonate: 0.01%, and the balance is deionized water.

[0038] The above components are mixed evenly to obtain the two-step texturing additive ②.

[0039] The two-step flocking process includes the following steps: 1. One-step texturing: In the one-step texturing tank, 0.5% sodium hydroxide by mass, 0.2% commercially available conventional additive (additive GT01V08A from Zhejiang Silicon One New Energy Technology Co., Ltd.) and deionized water are mixed evenly to form the first-step texturing solution. The temperature of the texturing tank is stabilized at 75℃. The monocrystalline silicon wafer is inserted into the basket and placed into the one-step texturing tank for reaction for 300 seconds.

[0040] 2. Washing: The silicon wafers after the first step of texturing are washed in a room temperature deionized water bath for 100 seconds to prepare for the second step of texturing.

[0041] 3. Two-step texturing: 0.1% sodium hydroxide, 0.1% two-step texturing additive ②, and deionized water are mixed evenly in the two-step texturing tank to obtain a two-step texturing solution. The sheet cleaned in step 2 is placed in the two-step texturing solution tank for texturing. The texturing temperature is 55℃ and the texturing time is 150s. The pyramid surface is etched to obtain a multi-folded, low-reflectivity texturing surface with double slopes on 111 faces.

[0042] 4. Wash and dry: After texturing in step 3, wash the wafer in a room temperature deionized water bath for 100 seconds, then put it into a drying bath to dry the silicon wafer at 80℃ for 700 seconds.

[0043] 5. Performance testing: The dried silicon wafers are subjected to reflectivity testing, surface texture data measurement, and morphology scanning.

[0044] like Figure 2 and Figure 3 As shown, the silicon wafer surface has a two-tiered structure of a pyramid base and a pyramid apex. The angle between the hypotenuse of the pyramid base and the base is 55° to 56°, and the angle between the hypotenuse of the pyramid apex and the hypotenuse of the pyramid base is between 168° and 179.8°.

[0045] Example 2 Additive composition used in the fabrication of double-slope pyramid structured single-crystal silicon: Polydextrose: 0.9%, sodium glycolate: 1.5%, sodium hydroxyethyl cellulose: 0.02%, sodium tert-butoxide: 0.9%, sodium hexadecyl sulfonate: 0.05%, balance: deionized water.

[0046] The above components are mixed evenly to obtain the two-step texturing additive ②.

[0047] The two-step flocking process includes the following steps: 1. One-step texturing: In the one-step texturing tank, 0.9% sodium hydroxide by mass, 0.3% commercially available conventional additive ① (additive GT01V08A from Zhejiang Silicon One New Energy Technology Co., Ltd.) and deionized water are mixed evenly to form the first-step texturing solution. The temperature of the texturing tank is stabilized at 77℃. The monocrystalline silicon wafer is inserted into the basket and placed into the one-step texturing tank for reaction for 285 seconds.

[0048] 2. Washing: The silicon wafers after the first step of texturing are washed in a room temperature deionized water bath for 115 seconds to prepare for the second step of texturing.

[0049] 3. Two-step texturing: 0.6% sodium hydroxide, 0.2% two-step texturing additive ② and deionized water are mixed evenly in the two-step texturing tank to obtain a two-step texturing solution. The sheet cleaned in step 2 is placed in the two-step texturing solution tank for texturing. The texturing temperature is 58℃ and the texturing time is 135s. The pyramid surface is etched to obtain a multi-folded, low-reflectivity texturing surface with double slope on 111 faces.

[0050] 4. Washing and drying: After texturing in step 3, wash the wafer in a room temperature deionized water bath for 115 seconds, then put it into a drying bath to dry the silicon wafer at 85℃ for 600 seconds.

[0051] 5. Performance testing: The dried silicon wafers are subjected to reflectivity testing, surface texture data measurement, and morphology scanning.

[0052] like Figure 4 As shown, the silicon wafer surface has a two-tiered structure of a pyramid base and a pyramid apex. The angle between the hypotenuse of the pyramid base and the base is 55° to 56°, and the angle between the hypotenuse of the pyramid apex and the hypotenuse of the pyramid base is between 168° and 179.8°.

[0053] Example 3 Additive composition used in the fabrication of double-slope pyramid structured single-crystal silicon: Glyceryl phosphate choline-carboxymethyl-β-cyclodextrin: 1.2%, sodium oxalate: 2.5%, sodium carboxymethyl cellulose: 0.03%, potassium ethoxide: 3%, sodium dioctyl sulfosuccinate: 0.09%, balance: deionized water.

[0054] The above components are mixed evenly to obtain the two-step texturing additive ②.

[0055] The two-step flocking process includes the following steps: 1. One-step texturing: In the one-step texturing tank, 1.2% sodium hydroxide by mass, 0.4% commercially available conventional additive ① (additive GT01V08A from Zhejiang Silicon One New Energy Technology Co., Ltd.) and deionized water are mixed evenly to form the first-step texturing solution. The temperature of the texturing tank is stabilized at 79℃. The monocrystalline silicon wafer is inserted into the basket and placed into the one-step texturing tank for reaction for 275 seconds.

[0056] 2. Water washing: The silicon wafers after the first step of texturing are washed in a room temperature deionized water bath for 125 seconds to prepare for the second step of texturing.

[0057] 3. Two-step texturing: Sodium hydroxide (1.2% by mass), two-step texturing additive ② (0.35% by mass), and deionized water are mixed evenly in the two-step texturing tank to obtain a two-step texturing solution. The sheet cleaned in step 2 is placed in the two-step texturing solution tank for texturing. The texturing temperature is 62℃ and the texturing time is 125s. The pyramid surface is etched to obtain a multi-folded, low-reflectivity texturing surface with double slopes on 111 faces.

[0058] 4. Washing and drying: After texturing in step 3, wash the wafer in a deionized water bath at room temperature for 125 seconds, and then put it into a drying bath to dry the silicon wafer at 90℃ for 500 seconds.

[0059] 5. Performance testing: The dried silicon wafers are subjected to reflectivity testing, surface texture data measurement, and morphology scanning.

[0060] Example 4 Additive composition used in the fabrication of double-slope pyramid structured single-crystal silicon: Konjac flour: 1.5%, sodium tartrate: 3%, sodium hydroxypropyl cellulose: 0.04%, potassium ethoxide: 1.7%, sodium fatty acid methyl ester sulfonate: 1.1%, balance: deionized water.

[0061] The above components are mixed evenly to obtain the two-step texturing additive ②.

[0062] The two-step flocking process includes the following steps: 1. One-step texturing: In the one-step texturing tank, 1.7% sodium hydroxide by mass, 0.5% commercially available conventional additive ① (additive GT01V08A from Zhejiang Silicon One New Energy Technology Co., Ltd.) and deionized water are mixed evenly to form the first-step texturing solution. The temperature of the texturing tank is stabilized at 81℃. The monocrystalline silicon wafer is inserted into the basket and placed into the one-step texturing tank for reaction for 265 seconds.

[0063] 2. Water washing: The silicon wafers after the first step of texturing are washed in a room temperature deionized water bath for 140 seconds to prepare for the second step of texturing.

[0064] 3. Two-step texturing: Sodium hydroxide (1.8% by mass), two-step texturing additive ② (0.5% by mass), and deionized water are mixed evenly in the two-step texturing tank to obtain a two-step texturing solution. The sheet cleaned in step 2 is placed in the two-step texturing solution tank for texturing. The texturing temperature is 65℃ and the texturing time is 115s. The pyramid surface is etched to obtain a multi-folded, low-reflectivity texturing surface with double slopes on 111 faces.

[0065] 4. Washing and drying: After texturing in step 3, wash the wafer in a deionized water bath at room temperature for 140 seconds, and then put it into a drying bath to dry the silicon wafer at 95℃ for 450 seconds.

[0066] 5. Performance testing: The dried silicon wafers are subjected to reflectivity testing, surface texture data measurement, and morphology scanning.

[0067] Example 5 Additive composition used in the fabrication of double-slope pyramid structured single-crystal silicon: Konjac flour: 2%, sodium glycolate: 5%, sodium hydroxybutyl cellulose: 0.05%, potassium ethoxide: 3%, sodium fatty acid methyl ester sulfonate: 2%, the remainder is deionized water.

[0068] The above components are mixed evenly to obtain the two-step texturing additive ②.

[0069] The two-step flocking process includes the following steps: 1. One-step texturing: In the one-step texturing tank, 2% sodium hydroxide by mass, 0.6% commercially available conventional additive ① (additive GT01V08A from Zhejiang Silicon One New Energy Technology Co., Ltd.) and deionized water are mixed evenly to form the first-step texturing solution. The temperature of the texturing tank is stabilized at 83℃. The monocrystalline silicon wafer is inserted into the basket and placed into the one-step texturing tank for reaction for 250 seconds.

[0070] 2. Washing: The silicon wafers after the first step of texturing are washed in a room temperature deionized water bath for 150 seconds to prepare for the second step of texturing.

[0071] 3. Two-step texturing: 3% sodium hydroxide, 0.6% two-step texturing additive ②, and deionized water are mixed evenly in the two-step texturing tank to obtain a two-step texturing solution. The sheet cleaned in step 2 is placed in the two-step texturing solution tank for texturing. The texturing temperature is 70℃ and the texturing time is 100s. The pyramid surface is etched to obtain a multi-folded, low-reflectivity texturing surface with double slopes on 111 faces.

[0072] 4. Wash and dry: After texturing in step 3, wash the wafer in a deionized water bath at room temperature for 150 seconds, and then put it into a drying bath to dry the silicon wafer at 100℃ for 400 seconds.

[0073] 5. Performance testing: The dried silicon wafers are subjected to reflectivity testing, surface texture data measurement, and morphology scanning.

[0074] Comparative Example 1 Compared to Example 1, only one texturing step was performed. Performance testing of the texturized monocrystalline silicon wafer showed a pyramidal morphology as follows: Figure 5 The surface of the pyramid is very smooth, and the sides of the pyramid have only one slope from the top to the bottom, such as... Figure 6 .

[0075] Comparative Example 2 Compared with Example 1, the additive used in the two-step texturing tank is sodium lactate-free. The performance test of the single-crystal wafers after texturing showed a pyramidal morphology as follows: Figure 7The surface of the pyramids has some folds, but the sides of the pyramids have only one slope from the top to the bottom, such as... Figure 8 It can be seen that only by using the specific two-step flocking additive of this invention can a pyramidal morphology with double slopes and multiple folds be obtained.

[0076] Comparative Example 3 Compared with Example 1, the additive used in the two-step texturing tank is sodium hydroxypropyl cellulose-free, and the performance of the single crystal wafer after texturing is tested.

[0077] Comparison table of reflectivity and pyramid size of texturized silicon wafers in Examples 1, 2, and 3 and Comparative Examples 1 and 2:

[0078] As can be seen from the data in the table, compared with comparative examples 1, 2, and 3, the texturing additive of the present invention can achieve a low reflectivity in Examples 1, 2, 3, 4, and 5. At the same time, the pyramid with a lower reflectivity has a larger specific surface area. A double-slope pyramid structure can only be obtained when slope control agent 1 and slope control agent 2 are present at the same time.

[0079] Figure 9 It is evident that the overall reflectivity of Example 1 in the 350-1050nm band is lower than that of Comparative Examples 1 and 2. The reflectivity of Example 1 is 2.36 lower than that of Comparative Example 1, and the reflectivity of Example 1 is 1.52 lower than that of Comparative Example 2. The low reflectivity is obtained by using the specific two-step texturing additive of this invention.

[0080] The above embodiments describe in detail the structure, features, and effects of the present invention. The above description is only a preferred embodiment of the present invention. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, shall still fall within the scope of protection of the present invention if they do not exceed the scope covered by the specification.

Claims

1. A monocrystalline silicon with a double-slope pyramid structure, characterized in that, The monocrystalline silicon has a pyramid base and a pyramid apex, wherein the angle between the hypotenuse of the pyramid base and the base side is 55° to 56°, and the angle between the hypotenuse of the pyramid apex and the hypotenuse of the pyramid base is 168° to 179.8°.

2. A method for preparing a single-crystal silicon with a double-slope pyramid structure as described in claim 1, characterized in that, The monocrystalline silicon wafer is first texturized in alkaline texturing solution A, and then the texturized silicon wafer is washed with water and placed in alkaline texturing solution B for the second texturization step; wherein alkaline texturing solution B includes slope control agent 1 and slope control agent 2; slope control agent 1 contains carboxylate group; slope control agent 2 contains hydroxyl group and hydrophobic terminal methyl group.

3. The method according to claim 2, characterized in that, The slope control agent 1 is one or more of sodium lactate, sodium glycolate, sodium oxalate, and sodium tartrate.

4. The method according to claim 2, characterized in that, Slope control agent 2 is one or more of sodium hydroxypropyl methylcellulose, sodium hydroxyethyl cellulose, sodium hydroxymethyl cellulose, sodium hydroxypropyl cellulose, and sodium hydroxybutyl cellulose.

5. The method according to claim 2, characterized in that, The mass percentage of alkali in the alkaline texturing solution is 0.5-2%; the texturing temperature for one-step texturing is 75-83℃, and the texturing time is 250s-300s.

6. The method according to claim 2, characterized in that, In alkaline texturing solution B, the mass percentage of alkali is 0.1-3%, and the mass percentage of additives is 0.1%-0.6%. The additives include slope control agent 1, slope control agent 2, defoaming agent, organic alkali, and wetting agent. The two-step texturing temperature is 55-70℃, and the texturing time is 90s-150s.

7. The method according to claim 6, characterized in that, The defoaming agent is one or more of polyfructose, polydextrose, glycerophosphate choline-carboxymethyl-β-cyclodextrin and konjac flour; The organic base is one or more of sodium tert-butoxide, potassium ethoxide, and sodium methoxide; The wetting agent is one or more of sodium lauryl hydroxyethyl sulfonate, sodium hexadecyl sulfonate dioctyl succinate sodium salt, and sodium fatty acid methyl ester sulfonate.

8. The method according to claim 6, characterized in that, The additives contain 1%-2% defoamer, 1%-5% slope control agent 1, 0.01%-0.05% slope control agent 2, 0.4%-3% organic alkali, 0.01%-2% wetting agent, and the remainder is deionized water.

9. The method according to claim 2, characterized in that, The silicon wafers obtained after the second texturing step are washed with water and then dried at a temperature of 80-100℃ for 400-700 seconds.

10. An application of a monocrystalline silicon with a double-slope pyramid structure as described in claim 1.

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