Texturing auxiliary etching agent for ultra-small suede structure of photovoltaic solar monocrystalline silicon cell and preparation method and application thereof

Abstract

The invention provides a texturing auxiliary etching agent for an ultra-small textured structure of a photovoltaic solar monocrystalline silicon cell and a preparation method and application of the texturing auxiliary etching agent. The texturing auxiliary etching agent is prepared from 0.5%-1.5% of a textured surface homogenizing agent, 0.1%-0.4% of salicylic acid, 0.05%-0.1% of sodium acetate, 0.1%-0.5% of alkali metal hydroxide, 0.1%-0.5% of sodium chloride, 0.5%-2.0% of sodium benzoate, 1.0%-3.0% of amylase and 92%-97.65% of deionized water. According to the texturing auxiliary etching agent disclosed by the invention, the uniform small texturing surface of a pyramid structure with the width of 0.88-1.15 microns can be effectively controlled, and the texturing auxiliary etching agent is uniformly distributed on the surface of a silicon wafer to form a small and dense texturing surface, so that the photoelectric conversion efficiency is improved; in addition, due to the fact that the pyramid is small, the corrosion amount is correspondingly reduced, the thinning amount can be reduced, the breakage rate is effectively reduced, and therefore the yield of coating is increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of wet texturing of photovoltaic solar cells, and relates to a texturing auxiliary etchant and a preparation method and application thereof, and in particular to a texturing auxiliary etchant for ultra-small texturing structure of photovoltaic solar monocrystalline silicon cells and a preparation method and application thereof. Background Art

[0002] In the wet process of photovoltaic solar cells, texturing plays a very important role. It mainly utilizes the differences in lattice corrosion inside the crystal, which easily forms a pyramid-like structure. Silicon mainly reacts with hydroxide, which can saponify some surface oil and remove the oxide layer, reducing the dirt problem on the production line. At the same time, the pyramid structure spread on the surface of the silicon wafer can greatly increase the surface area of ​​the silicon wafer, enhance the absorption spectrum range, and indirectly improve the photoelectric conversion efficiency.

[0003] The monocrystalline silicon texturing additives currently used in photovoltaic solar cells form structures with a thickness of 1.6 to 1.9 μm. Due to the large pyramid base, these structures present significant fill factor losses in electrical performance and the uneven, undulating structure can cause color variations in subsequent coating processes, indirectly impacting photovoltaic photoelectric conversion and the yield of finished cells. Furthermore, the large pyramid structure requires a high etching weight, which increases the breakage rate of the production line by 4 to 10%.

[0004] Therefore, there is a need in the art to develop a texture additive that can further optimize single crystal silicon cells. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a texturing auxiliary etchant and its preparation method and application, and in particular to provide a texturing auxiliary etchant for ultra-small texturing structure of photovoltaic solar monocrystalline silicon cells and its preparation method and application.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In one aspect, the present invention provides a texturing auxiliary etchant, which comprises the following components in percentage by weight:

[0008] Suede surface leveling agent 0.5-1.5%, salicylic acid 0.1-0.4%, sodium acetate 0.05-0.1%, alkali metal hydroxide 0.1-0.5%, sodium chloride 0.1-0.5%, sodium benzoate 0.5-2.0%, amylase 1.0-3.0%, deionized water 92-97.65%.

[0009] In the present invention, the texturing auxiliary etchant can effectively control the pyramid structure to have uniform small velvet surfaces with a width of 0.88-1.15 μm, which are evenly distributed on the surface of the silicon wafer to form a small and dense velvet surface. Since the pyramid has a smaller corrosion amount, the thinning amount can be reduced, which greatly improves the photoelectric conversion efficiency and the yield of the coating, while effectively reducing the breakage rate.

[0010] In the present invention, the velvet surface uniformity agent can promote the reaction between hydroxide ions and silicon wafers, thereby improving the uniformity of the corroded pyramid structure. The acidic group in salicylic acid can control the corrosion rate and make the corrosion reaction more uniform. The action mechanism of sodium acetate is similar to that of salicylic acid and has a reinforcing effect on salicylic acid. During the reaction process, a difference in the rate of edge corrosion and the rate of corrosion in the middle area is likely to occur. Sodium acetate can promote edge corrosion and keep the edge and middle corrosion rates consistent. The functions of alkali metal hydroxide (sodium hydroxide or potassium hydroxide) and sodium benzoate are to control the stability of the formula system, prevent mildew, and extend the shelf life. Sodium chloride can assist in removing oil stains and organic impurities on the surface of the silicon wafer during the etching process. Amylase can accelerate the rate at which hydrogen leaves the interface, which is beneficial to the uniformity of the silicon wafer etching morphology.

[0011] In the texturing auxiliary etchant of the present invention, the amount of the texture surface leveling agent can be 0.5%, 0.8%, 1%, 1.2%, 1.4% or 1.5%, the amount of salicylic acid can be 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35% or 0.4%, the amount of sodium acetate can be 0.05%, 0.08% or 0.1%, the amount of alkali metal hydroxide can be 0.1%, 0.2%, 0.3%, 0.4% or 0.5%, the amount of sodium chloride can be 0.1%, 0.2%, 0.3%, 0.4% or 0.5%, the amount of sodium chloride can be 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35% or 0.4%, the amount of sodium acetate can be 0.05%, 0.08% or 0.1%, the amount of alkali metal hydroxide ...1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.4% or 0.5%, the amount of sodium chloride can be 0. The amount of the deionized water can be 92%, 92.3%, 92.5%, 93%, 94%, 95%, 96% or 97%.

[0012] Preferably, the velvet uniformity agent is a polysaccharide with a molecular weight of 30,000 to 90,000 (for example, 30,000, 35,000, 40,000, 45,000, 50,000, 60,000, 70,000, 80,000 or 90,000), a chitosan oligosaccharide with a molecular weight of 40,000 to 100,000 (for example, 40,000, 45,000, 50,000, 60,000, 70,000, 80,000, 90,000 or 100,000), a seaweed polysaccharide, a chitosan and a mixture of at least two of them.

[0013] Preferably, the molecular weight of the seaweed polysaccharide is in the range of 50,000 to 65,000, such as 50,000, 53,000, 55,000, 58,000, 60,000, 63,000 or 65,000.

[0014] Preferably, the molecular weight of the chitosan is in the range of 140,000 to 170,000, such as 140,000, 150,000, 160,000 or 170,000.

[0015] Preferably, the molecular weight of the dextran is in the range of 8000 to 10000, such as 8000, 8500, 9000, 9500 or 10000.

[0016] Preferably, the alkali metal hydroxide is potassium hydroxide and / or sodium hydroxide.

[0017] Preferably, the molecular weight of the amylase is 20,000 to 70,000, for example, 20,000, 23,000, 25,000, 30,000, 35,000, 40,000, 45,000, 50,000, 55,000, 60,000, 65,000 or 70,000.

[0018] On the other hand, the present invention provides a method for preparing the texturing auxiliary etchant as described above, the preparation method comprising the following steps:

[0019] (1) Mixing a suede surface uniformity agent with deionized water to obtain solution A;

[0020] (2) mixing salicylic acid, sodium acetate, alkali metal hydroxide, sodium chloride, sodium benzoate, amylase and deionized water to obtain solution B;

[0021] (3) Adding solution A to solution B and mixing them to obtain the texturing auxiliary etchant.

[0022] Preferably, the mixing in step (1) is carried out at a temperature of 60-70°C (e.g., 60°C, 63°C, 65°C, 68°C or 70°C), and the mixing time is 1.5-3 hours (e.g., 1.5 hours, 1.8 hours, 2 hours, 2.3 hours, 2.5 hours, 2.8 hours or 3 hours).

[0023] Preferably, the mixing in step (1) is carried out under stirring.

[0024] Preferably, the mixing in step (3) is carried out under stirring.

[0025] Preferably, the mixing in step (3) is carried out at 40-60°C (eg, 40°C, 43°C, 45°C, 48°C, 50°C, 55°C, 58°C or 60°C).

[0026] Preferably, the mixing time in step (3) is 20-40 min, for example, 20 min, 25 min, 30 min, 35 min or 40 min.

[0027] Preferably, the mixture is cooled to room temperature after mixing in step (3).

[0028] On the other hand, the present invention provides a texturing etching solution, which includes the texturing auxiliary etchant as described above.

[0029] Preferably, the texturing etching solution comprises an alkaline solution and the texturing auxiliary etchant as described above.

[0030] Preferably, the alkaline solution is potassium hydroxide solution or sodium hydroxide solution.

[0031] Preferably, the concentration of the alkaline solution is 1.8-2.5%, such as 1.8%, 2.0%, 2.2%, 2.4% or 2.5%.

[0032] Preferably, the concentration of the additive in the texturing etching solution is 0.2-0.5%, for example, 0.2%, 0.3%, 0.4% or 0.5%.

[0033] On the other hand, the present invention provides a method for single crystal texturing etching using the above-mentioned texturing etching solution, the method comprising the following steps:

[0034] The single crystal silicon wafer is immersed in a texturing etching solution for texturing.

[0035] Preferably, the texturing temperature is 75-80°C (for example, 75°C, 78°C or 80°C), and the texturing reaction time is 250-600 seconds (for example, 250 seconds, 280 seconds, 300 seconds, 350 seconds, 400 seconds, 450 seconds, 500 seconds, 550 seconds or 600 seconds).

[0036] On the other hand, the present invention provides a single crystal silicon wafer prepared by the single crystal texturing and etching method as described above.

[0037] In another aspect, the present invention provides a photovoltaic solar monocrystalline silicon cell comprising the monocrystalline silicon wafer described above.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The present invention uses biopolysaccharide materials, which can quickly disperse in aqueous solution and gather on the surface of the silicon wafer for adsorption. Due to the low molecular weight and internal spatial structure, the surface tension can be effectively reduced. The pyramids formed on the velvet surface after etching are small and evenly arranged, which further reduces the reflectivity of the silicon wafer.

[0040] The velvet leveler of the present invention quickly disperses in an alkaline hot environment and forms micron-sized micelles in the solution. Since silicon exhibits a strong negative charge in the aqueous solution, a relatively strong adsorption effect is formed. As the reaction proceeds, a large amount of hydrogen is released, and the velvet leveler is firmly adsorbed at the top of the pyramid. The presence of some inorganic salts also ensures the uniform progress of the reaction. As time goes by, small and dense pyramid structures are gradually formed, which can greatly improve the filling factor in photoelectric conversion, and at the same time greatly reduce the thinning amount, thereby reducing the color difference caused by the subsequent coating process. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0042] Example 1

[0043] The invention discloses an auxiliary etching agent for making ultra-small textured structures of photovoltaic solar monocrystalline silicon cells. The auxiliary etching agent comprises, by weight percentage, 0.8% of a textured surface leveling agent, 0.1% of salicylic acid, 0.05% of sodium acetate, 0.22% of potassium hydroxide, 0.25% of sodium chloride, 1.05% of sodium benzoate, 2.15% of amylase, and 95.38% of deionized water.

[0044] In this embodiment, the suede surface leveling agent used is chitosan, purchased from McLean, MDL No.: MFCD00161512, molecular weight: 58000, and amylase is purchased from McLean, MDL No.: MFCD00146469.

[0045] The method for preparing the texturing auxiliary etchant as described above comprises the following steps:

[0046] S1. Add the velvet leveling agent into a container in advance and mix with deionized water (the amount used is 21% of the total deionized water). Maintain the temperature at 65°C and stir continuously for 2 hours to obtain solution A.

[0047] S2. Add salicylic acid, sodium acetate, potassium hydroxide, sodium chloride, sodium benzoate, and amylase into a container and mix with deionized water to obtain solution B;

[0048] S3. Continuously stir the B solution, add the A solution into the B solution, stir and mix at 50° C. for 30 minutes, and cool to room temperature to obtain an auxiliary etching agent for the texturing of ultra-small texturing structures of photovoltaic solar monocrystalline silicon cells.

[0049] The method for performing texturing etching using the texturing auxiliary etchant as described above comprises the following steps:

[0050] S1. Prepare a texturing etching solution; add the ultra-small textured surface structure texturing auxiliary etchant to a sodium hydroxide solution, mix them evenly to form a texturing solution, wherein the concentration of sodium hydroxide is 2.0% and the concentration of the additive is 0.3%.

[0051] S2. Etching and texturing of the surface of single crystal silicon: the texturing temperature is controlled at 80°C, and the single crystal silicon wafer is immersed in the texturing etching solution of S1. The reaction time is 500 seconds to obtain the silicon wafer after texturing.

[0052] Example 2

[0053] The invention discloses an auxiliary etching agent for texturing an ultra-small textured structure of a photovoltaic solar monocrystalline silicon cell. The auxiliary etching agent comprises the following components, calculated as 100% by mass: 1.05% of a textured surface leveling agent, 0.2% of salicylic acid, 0.08% of sodium acetate, 0.30% of potassium hydroxide, 0.33% of sodium chloride, 1.5% of sodium benzoate, 2.25% of amylase, and 94.29% of deionized water.

[0054] In this embodiment, the velvet surface uniformity agent used is chitosan, purchased from McLean, MDL number: MFCD00161512, molecular weight: 72000, and amylase is purchased from Titan, product number: 01122995;

[0055] The method for preparing the auxiliary etching agent for texturing ultra-small textured structure of photovoltaic solar single crystal silicon cells as described above comprises the following steps:

[0056] S1. Add the velvet leveling agent into a container in advance and mix with deionized water (the amount used is 21% of the total deionized water). Maintain the temperature at 65°C and stir continuously for 2 hours to obtain solution A.

[0057] S2. Add salicylic acid, sodium acetate, potassium hydroxide, sodium chloride, sodium benzoate, and amylase into a container and mix with deionized water to obtain solution B;

[0058] S3. Continuously stir solution B, add solution A into solution B, stir and mix at 40° C. for 30 minutes, and cool to room temperature to obtain an auxiliary etching agent for texturing an ultra-small texturing structure of photovoltaic solar single-crystal silicon cells.

[0059] The method for performing texturing etching using the texturing auxiliary etchant as described above comprises the following steps:

[0060] S1, preparing a texturing etching solution; adding the ultra-small textured surface structure texturing auxiliary etchant to a sodium hydroxide solution, mixing them evenly to form a texturing solution, wherein the concentration of sodium hydroxide is 2.0% and the concentration of the additive is 0.3%;

[0061] S2. Etching and texturing of the surface of single crystal silicon: the texturing temperature is controlled at 80°C, the single crystal silicon wafer is immersed in S1, the reaction time is 600 seconds, and the silicon wafer with texturing is obtained.

[0062] Example 3

[0063] A texturing auxiliary etchant for ultra-small textured structures of photovoltaic solar monocrystalline silicon cells, comprising the following components, calculated as 100% by mass: 1.3% texture leveling agent, 0.3% salicylic acid, 0.1% sodium acetate, 0.5% potassium hydroxide, 0.4% sodium chloride, 2.0% sodium benzoate, 3.0% amylase, and 92.4% deionized water;

[0064] In this embodiment, the velvet surface leveling agent is seaweed polysaccharide with a molecular weight of 50,000, purchased from Maclean, MDL number: MFCD00081310; amylase is purchased from Sinopharm Reagent, with a national medicine code of 64003436 and a molecular weight of 43,000.

[0065] A method for preparing an auxiliary etching agent for texturing an ultra-small textured structure of a photovoltaic solar single-crystal silicon cell comprises the following steps:

[0066] S1. Add the velvet leveling agent into a container in advance and mix with deionized water (the amount used is 21% of the total deionized water). Maintain the temperature at 65°C and stir continuously for 2 hours to obtain solution A.

[0067] S2. Add salicylic acid, sodium acetate, potassium hydroxide, sodium chloride, sodium benzoate, and amylase into a container and mix with deionized water to obtain solution B;

[0068] S3. Continuously stir the B solution, add the A solution into the B solution, stir and mix at 60° C. for 30 minutes, and cool to room temperature to obtain the photovoltaic solar single crystal silicon cell ultra-small textured structure texturing auxiliary etchant.

[0069] The texturing etching method using the texturing auxiliary etchant as described above comprises the following steps:

[0070] S1, preparing a texturing etching solution; adding the ultra-small textured surface structure texturing auxiliary etchant to a sodium hydroxide solution, mixing them evenly to form a texturing solution, wherein the concentration of the sodium hydroxide solution is 2.0% and the concentration of the additive is 0.3%;

[0071] S2. Etching and texturing of the surface of single crystal silicon: the texturing temperature is controlled at 80°C, the single crystal silicon wafer is immersed in S1, the reaction time is 300 seconds, and the silicon wafer with texturing is obtained.

[0072] Example 4

[0073] A texturing auxiliary etchant for ultra-small textured structures of photovoltaic solar monocrystalline silicon cells, comprising the following components, calculated as 100% by mass: 0.5% texture leveling agent, 0.1% salicylic acid, 0.1% sodium acetate, 0.1% potassium hydroxide, 0.1% sodium chloride, 0.1% sodium benzoate, 1% amylase, and 98% deionized water;

[0074] In this embodiment, the velvet surface uniformity agent is seaweed polysaccharide with a molecular weight of 60,000, purchased from Sinopharm, model: 30164424; amylase is purchased from McLean, model: MFCD00081319, with a molecular weight of 34,000;

[0075] A method for preparing an auxiliary etching agent for texturing an ultra-small textured structure of a photovoltaic solar single-crystal silicon cell comprises the following steps:

[0076] S1. Add the velvet leveling agent into a container in advance and mix with deionized water (the amount used is 21% of the total deionized water). Maintain the temperature at 65°C and stir continuously for 2 hours to obtain solution A.

[0077] S2. Add salicylic acid, sodium acetate, potassium hydroxide, sodium chloride, sodium benzoate, and amylase into a container and mix with deionized water to obtain solution B;

[0078] S3. Continuously stir the B solution, add the A solution into the B solution, stir and mix at 50° C. for 30 minutes, and cool to room temperature to obtain the photovoltaic solar single crystal silicon cell ultra-small textured structure texturing auxiliary etchant.

[0079] The texturing etching method using the texturing auxiliary etchant as described above comprises the following steps:

[0080] S1, preparing a texturing etching solution; adding the ultra-small textured surface structure texturing auxiliary etchant to a sodium hydroxide solution, mixing them evenly to form a texturing solution, wherein the concentration of the sodium hydroxide solution is 2.0% and the concentration of the additive is 0.3%;

[0081] S2. Etching and texturing of the surface of single crystal silicon: the texturing temperature is controlled at 80°C, the single crystal silicon wafer is immersed in S1, the reaction time is 250 seconds, and the silicon wafer after texturing is obtained.

[0082] Example 5

[0083] A texturing auxiliary etchant for ultra-small textured structures of photovoltaic solar monocrystalline silicon cells, comprising the following components, calculated as 100% by mass: 1.5% texture leveling agent, 0.3% salicylic acid, 0.05% sodium acetate, 0.5% potassium hydroxide, 0.5% sodium chloride, 2% sodium benzoate, 3% amylase, and 92.15% deionized water;

[0084] In this embodiment, the velvet surface uniformity agent is seaweed polysaccharide with a molecular weight of 30,000, purchased from McLean, model: MFCD00081310, and amylase with a molecular weight of 20,000 to 70,000, purchased from McLean, model: MFCD00081310, with a molecular weight of 67,000.

[0085] A method for preparing an auxiliary etching agent for texturing an ultra-small textured structure of a photovoltaic solar single-crystal silicon cell comprises the following steps:

[0086] S1. Add the velvet leveling agent into a container in advance and mix with deionized water (the amount used is 21% of the total deionized water). Maintain the temperature at 65°C and stir continuously for 2 hours to obtain solution A.

[0087] S2. Add salicylic acid, sodium acetate, potassium hydroxide, sodium chloride, sodium benzoate, and amylase into a container and mix with deionized water to obtain solution B;

[0088] S3. Continuously stir the B solution, add the A solution into the B solution, stir and mix at 45° C. for 30 minutes, and cool to room temperature to obtain the photovoltaic solar single crystal silicon cell ultra-small textured structure texturing auxiliary etchant.

[0089] The texturing etching method using the texturing auxiliary etchant as described above comprises the following steps:

[0090] S1, preparing a texturing etching solution; adding the ultra-small textured surface structure texturing auxiliary etchant to a sodium hydroxide solution, mixing them evenly to form a texturing solution, wherein the concentration of the sodium hydroxide solution is 2.0% and the concentration of the additive is 0.3%;

[0091] S2. Etching and texturing of the surface of single crystal silicon: the texturing temperature is controlled at 80°C, the single crystal silicon wafer is immersed in S1, the reaction time is 250 seconds, and the silicon wafer after texturing is obtained.

[0092] Example 6

[0093] The only difference from Example 1 is that the suede surface uniformity agent in this example is chitosan oligosaccharide purchased from Maclean, with a molecular weight of ≤2000.

[0094] Example 7

[0095] The only difference from Example 1 is that the suede surface uniformity agent in this embodiment is chitosan purchased from McLean, with a molecular weight of 100,000.

[0096] Comparative Example 1

[0097] The texturing additive used in this comparative example was purchased from Changzhou Shichuangxin Energy Co., Ltd., and the commercially available product model is TS-57.

[0098] The method for texturing and etching with a texturing auxiliary etchant comprises the following steps:

[0099] S1, preparing a texturing etching solution; adding the ultra-small textured surface structure texturing auxiliary etchant to a sodium hydroxide solution, mixing them evenly to form a texturing solution, wherein the concentration of the sodium hydroxide solution is 2.0% and the concentration of the additive is 0.3%;

[0100] S2. Etching and texturing of the surface of single crystal silicon: the texturing temperature is controlled at 80°C, the single crystal silicon wafer is immersed in S1, the reaction time is 250 seconds, and the silicon wafer after texturing is obtained.

[0101] Comparative Example 2

[0102] The difference from Example 1 is that the texturing auxiliary etchant does not contain amylase, and the amount of deionized water used is 97.53%.

[0103] Comparative Example 3

[0104] The difference from Example 1 is that the texturing auxiliary etchant does not contain sodium acetate, and the amount of deionized water used is 95.43%.

[0105] Comparative Example 4

[0106] The difference from Example 1 is that the texturing auxiliary etchant does not contain sodium chloride, and the amount of deionized water used is 95.63%.

[0107] Comparative Example 5

[0108] The difference from Example 1 is that the texturing auxiliary etchant does not contain sodium benzoate, and the amount of deionized water used is 96.43%.

[0109] The texturing auxiliary agents in the examples and comparative examples were used, and the cell texturing methods in the examples and comparative examples were used to etch the surface of single crystal silicon. The experimental results are shown in Table 1 below.

[0110] Table 1

[0111]

[0112] The average base size, number, average height and surface ratio of the pyramids are tested by the professional instrument Zeta-20 3D profilometer, and the reflectivity is tested by the D8 reflectivity meter.

[0113] Thinning amount: Use a precision electronic balance to test, the weight of the silicon wafer before etching minus the weight of the silicon wafer after etching = thinning amount (in grams).

[0114] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate the auxiliary etching agent for the ultra-small textured structure of photovoltaic solar monocrystalline silicon cells and its preparation method and application, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of various raw materials of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the scope of protection and disclosure of the present invention.

Claims

1. A texturing auxiliary etchant, characterized in that: The texturing auxiliary etchant comprises the following components in percentage by weight: Suede surface leveling agent 0.5-1.5%, salicylic acid 0.1-0.4%, sodium acetate 0.05-0.1%, alkali metal hydroxide 0.1-0.5%, sodium chloride 0.1-0.5%, sodium benzoate 0.5-2.0%, amylase 1.0-3.0%, deionized water 92-97.65%.

2. The texturing auxiliary etchant according to claim 1, characterized in that: The velvet surface uniformity agent is one or a mixture of at least two of chitosan oligosaccharides, seaweed polysaccharides, chitosan and dextran; Preferably, the molecular weight of the seaweed polysaccharide is in the range of 50,000 to 65,000; Preferably, the molecular weight of the chitosan is in the range of 140,000 to 170,000; Preferably, the molecular weight of the dextran is in the range of 8000 to 10000; Preferably, the alkali metal hydroxide is potassium hydroxide and / or sodium hydroxide.

3. The texturing auxiliary etchant according to claim 1, characterized in that: The molecular weight of the amylase is 20,000 to 70,000.

4. The method for preparing a texturing auxiliary etchant according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: (1) Mixing a suede surface uniformity agent with deionized water to obtain solution A; (2) mixing salicylic acid, sodium acetate, alkali metal hydroxide, sodium chloride, sodium benzoate, amylase and deionized water to obtain solution B; (3) Adding solution A to solution B and mixing them to obtain the texturing auxiliary etchant.

5. The preparation method according to claim 4, characterized in that The mixing in step (1) is carried out at a temperature of 60-70° C. for 1.5-3 hours; Preferably, the mixing in step (1) is carried out under stirring; Preferably, the mixing in step (3) is carried out under stirring; Preferably, the mixing in step (3) is carried out at 40-60°C; Preferably, the mixing time in step (3) is 20-40 min; Preferably, the mixture is cooled to room temperature after mixing in step (3).

6. A texturing etching solution, characterized in that: The texturing etching solution comprises the texturing auxiliary etching agent according to any one of claims 1 to 3; Preferably, the texturing etching solution comprises an alkaline solution and a texturing auxiliary etchant according to any one of claims 1 to 3; Preferably, the alkaline solution is potassium hydroxide solution or sodium hydroxide solution; Preferably, the concentration of the alkaline solution is 1.8-2.5%; Preferably, the concentration of the additive in the texturing etching solution is 0.2-0.5%.

7. A method for single crystal texturing etching using the texturing etching solution according to claim 6, characterized in that: The method comprises the following steps: immersing a single crystal silicon wafer in the texturing etching solution according to claim 6 to perform texturing.

8. The method according to claim 7, characterized in that The texturing temperature is 75-80° C., and the texturing reaction time is 250-600 seconds.

9. A single crystal silicon wafer prepared by the single crystal texturing and etching method according to claim 7 or 8.

10. A photovoltaic solar monocrystalline silicon cell, characterized in that: The photovoltaic solar monocrystalline silicon cell comprises the monocrystalline silicon wafer as claimed in claim 9.

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