Texturing additive for pyramid suede monocrystalline silicon wafer and preparation method of texturing additive

Abstract

The invention relates to the technical field of texturing additives for monocrystalline silicon wafers, and discloses a texturing additive for a pyramid textured monocrystalline silicon wafer and a preparation method of the texturing additive. Comprising the following raw materials in parts by mass: 1-1.5 parts of organic sulfonate, 1-2 parts of a polyamine high-molecular compound, 1-2 parts of a high-molecular polymer, 0.5-1 part of a surfactant, 0.2-0.5 part of a composite additive and 90-110 parts of deionized water. The composite additive contains a large number of carboxyl groups, hydroxyl groups and amino groups, the adsorption performance of the texturing additive on the surface of the monocrystalline silicon wafer can be enhanced, then a uniform pyramid structure is formed, the reflectivity is reduced, and the contained modified nano titanium dioxide can form a nano composite film on the surface of the monocrystalline silicon wafer, so that the texturing effect is improved. And the surface roughness and the scattering effect are further improved.

Description

Technical Field

[0001] This invention relates to the field of texturing additives for monocrystalline silicon wafers, specifically to a texturing additive for pyramid-textured monocrystalline silicon wafers and its preparation method. Background Technology

[0002] Silicon-based photovoltaic cells are the main technology of solar cells. Among them, the textured surface of crystalline silicon is a key factor that determines the reflectivity and cell performance. In the preparation of monocrystalline silicon solar cells, texturing is its core process. A pyramid-like textured surface is formed on the silicon wafer surface, which in turn creates a light trapping effect, increases the number of reflections of light on the silicon wafer surface, improves the light absorption rate, reduces the reflectivity of the silicon wafer surface, and thus improves the conversion efficiency of monocrystalline silicon solar cells.

[0003] Typically, alkaline solutions are used to anisotropically etch the junctions of crystalline silicon solar cells. Various monocrystalline silicon texturing additives are then used to regulate the reaction rate between the alkali and silicon, control the micro-nano structure, and facilitate the formation of pyramidal textured surfaces to improve the overall performance of the cell. However, current monocrystalline silicon texturing additives suffer from problems such as large and uneven surface pyramids and long texturing times, making it difficult to effectively reduce reflectivity and affecting the photoelectric conversion efficiency of solar cells. Summary of the Invention

[0004] This invention provides a texturing additive for pyramid-patterned monocrystalline silicon wafers and its preparation method, which solves the problems of large surface pyramids, uneven pyramids, and long texturing time in monocrystalline silicon wafer texturing additives.

[0005] The technical solution of the present invention: A texturing additive for pyramid-textured monocrystalline silicon wafers comprises the following raw materials in parts by weight: 1-1.5 parts of organic sulfonate, 1-2 parts of polyamine polymer, 1-2 parts of polymer, 0.5-1 part of surfactant, 0.2-0.5 parts of composite additive, and 90-110 parts of deionized water. The composite additive is obtained by synthesizing a silica layer on the surface of nano-titanium dioxide, and then reacting it with a chitosan-based modifier and ethylene glycol. The chitosan-based modifier is obtained by grafting carboxymethyl chitosan with a silane coupling agent and then reacting it with acrylic acid, acrylamide, and isobutylene alcohol.

[0006] A method for preparing a texturing additive for pyramid-textured monocrystalline silicon wafers includes the following preparation steps: Organic sulfonate, polyamine polymer, polymer, surfactant, composite additive and deionized water are mixed and stirred for 30-60 minutes at 20-30℃ and 800-1500 r / min to obtain a flocking additive.

[0007] Furthermore, the organic sulfonate is selected from any one of sodium polystyrene sulfonate, sodium polynaphthalene sulfonate, and acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer.

[0008] Furthermore, the polyamine polymer is selected from polyethyleneimine or polyallylamine.

[0009] Furthermore, the polymer is selected from polyacrylamide or polymaleic anhydride.

[0010] Furthermore, the surfactant is selected from any one of sodium lauryl ether sulfate, lauryl polyoxyethylene ether, sodium dodecyl sulfate, methyl oleate ethoxylate, and glycerol fatty acid ester sulfate.

[0011] Furthermore, the composite additive is prepared by the following steps: A1. Carboxymethyl chitosan was added to an aqueous acetic acid solution and stirred until completely dissolved. Then, a silane coupling agent and ethanol were added, and the reaction was stirred until complete. After filtration, washing, and drying, double-bonded chitosan was obtained. A2. Add double-bonded chitosan to deionized water and stir until completely dispersed. Add acrylamide, acrylic acid, and isobutylene alcohol, stir evenly, purge with nitrogen, add ammonium persulfate, and stir the reaction at 65-70℃ for 4-6 hours. Cool to room temperature to obtain a viscous liquid. Place the viscous liquid in ethanol to form a precipitate. Collect the precipitate, wash and dry it to obtain the chitosan-based modifier. A3. Mix nano-titanium dioxide and deionized water, stir evenly, add sodium hydroxide solution to adjust pH, add tetraethyl orthosilicate and ethanol, stir to react to form a gel, remove the gel, filter, wash and dry to obtain modified nano-titanium dioxide. A4. Add the chitosan-based modifier to deionized water and stir until homogeneous. Add the modified nano-titanium dioxide and ethylene glycol and stir until homogeneous. Add hydrochloric acid to adjust the pH and then stir to react. After filtration, washing, and drying, the composite additive is obtained.

[0012] Furthermore, during the A1 reaction described above, the hydroxyl groups generated by the hydrolysis of the silane coupling agent can chemically bond with the carboxyl groups on the carboxymethyl chitosan molecular chain, thereby grafting the silane coupling agent onto the carboxymethyl chitosan molecular chain to obtain double-bonded chitosan.

[0013] Furthermore, in the A2 reaction process described above, ammonium persulfate acts as an initiator, enabling the double-bonded chitosan to copolymerize with the double bonds carried by acrylic acid, acrylamide, and isobutylene alcohol, thereby grafting acrylic acid, acrylamide, and isobutylene alcohol onto the double-bonded chitosan molecular chain to obtain a chitosan-based modifier.

[0014] Furthermore, during the A3 reaction described above, under alkaline conditions, the hydroxyl groups generated by the hydrolysis of tetraethyl orthosilicate can chemically bond with the hydroxyl groups on the surface of nano-titanium dioxide. As the hydrolysis and condensation reaction proceeds, the silica formed by the hydrolysis of tetraethyl orthosilicate is coated onto the surface of nano-titanium dioxide, thereby achieving the coating of a silica layer on the surface of nano-titanium dioxide and obtaining modified nano-titanium dioxide.

[0015] Furthermore, during the A4 reaction process described above, the modified nano-titanium dioxide is mixed and reacted with chitosan-based modifier and ethylene glycol. Under acidic conditions, the hydroxyl groups contained in the ethylene glycol can chemically bond with the hydroxyl groups on the surface of the modified nano-titanium dioxide and the polar functional groups in the chitosan-based modifier, thereby dispersing the modified nano-titanium dioxide in the chitosan-based modifier to obtain a composite additive.

[0016] Further, in step A1, the mass ratio of carboxymethyl chitosan, aqueous acetic acid solution, silane coupling agent and ethanol is (2-2.4):(30-40):(1-1.2):(80-90).

[0017] Further, in step A2, the mass ratio of double-bonded chitosan, deionized water, acrylamide, acrylic acid, isobutylene alcohol, and ammonium persulfate is (2-2.5):(50-60):(0.8-1):(1-1.2):(1.1-1.3):(0.05-0.1).

[0018] Furthermore, in step A2, the mass ratio of the viscous liquid to ethanol is 1:(5-8).

[0019] Further, in step A3, the mass ratio of nano-titanium dioxide, deionized water, tetraethyl orthosilicate and ethanol is (1-1.3):(45-50):(2-2.5):(90-95).

[0020] Further, in step A4, the mass ratio of chitosan-based modifier, deionized water, modified nano-titanium dioxide, and ethylene glycol is (2-2.3):(50-60):(1-1.2):(0.8-1).

[0021] The present invention has the following beneficial effects: (1) In the technical solution of the present invention, the silane coupling agent is grafted onto the carboxymethyl chitosan molecular chain, giving the carboxymethyl chitosan a double bond that can copolymerize, which is beneficial to introduce a large number of hydroxyl, amino and carboxyl functional groups on the carboxymethyl chitosan molecular chain, improve the adsorption of texturing additive on the surface of monocrystalline silicon wafer, effectively control the corrosion rate of the surface of monocrystalline silicon wafer, form a uniformly textured pyramid structure on the surface of monocrystalline silicon wafer, significantly reduce the reflectivity of monocrystalline silicon wafer, and improve the light absorption conversion efficiency of monocrystalline silicon wafer.

[0022] (2) In the technical solution of the present invention, acrylic acid, acrylamide, and isobutylene alcohol are grafted onto the double-bonded chitosan molecular chain. On the one hand, acrylic acid and isobutylene alcohol carry a large number of carboxyl and hydroxyl groups. By introducing anionic groups, the alkali resistance of chitosan is improved, and the glycosidic bonds of chitosan are prevented from breaking easily under alkaline conditions, which leads to polymer degradation and affects the texturing effect of the texturing additive. The amine group carried by acrylamide has weak cationic characteristics, which can enhance the adsorption performance of the texturing additive on the surface of the monocrystalline silicon wafer under alkaline conditions. On the other hand, the double-bonded chitosan serves as a carrier, providing a large number of binding sites for acrylic acid, acrylamide, and isobutylene alcohol. This is beneficial for imparting a large number of carboxyl, hydroxyl, and amino groups to the double-bonded chitosan molecular chain, enhancing the adsorption performance of the texturing additive on the surface of the monocrystalline silicon wafer, thereby forming a uniform pyramid structure, reducing reflectivity, and improving photoelectric conversion efficiency and photovoltaic cell performance.

[0023] (3) In the technical solution of the present invention, a modified nano-titanium dioxide is formed by coating a silicon dioxide layer on the surface of nano-titanium dioxide. On the one hand, when light shines on the surface of nano-titanium dioxide, strong light scattering will occur, increasing the propagation path of light on the single crystal silicon wafer, thereby reducing the reflectivity. The silicon dioxide layer also has good light reflection performance, further reducing the reflectivity of the single crystal silicon wafer. On the other hand, the formed modified nano-titanium dioxide can form a nanocomposite film on the surface of the single crystal silicon wafer, further increasing the surface roughness and scattering effect, effectively reducing the surface reflectivity of the single crystal silicon wafer, and further improving the light absorption efficiency of the single crystal silicon cell.

[0024] (4) In the technical solution of the present invention, the modified nano-titanium dioxide is dispersed in chitosan-based modifier by ethylene glycol. On the one hand, chitosan-based modifier can improve the dispersibility of modified nano-titanium dioxide in texturing additive, avoid the agglomeration of modified nano-titanium dioxide in texturing additive, and affect the texturing effect of texturing additive. On the other hand, chitosan-based modifier has good adsorption performance and can be adsorbed on the surface of monocrystalline silicon wafer, improve the bonding force of modified nano-titanium dioxide on the surface of monocrystalline silicon wafer, avoid the poor bonding force of modified nano-titanium dioxide on the surface of monocrystalline silicon wafer, and affect the structure of nanocomposite film, further increase the surface roughness and scattering effect, reduce the surface reflectivity of monocrystalline silicon wafer, and thus improve the light absorption efficiency of monocrystalline silicon cell. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1This is a scanning electron microscope image of a single-crystal silicon wafer after texturing with the texturing additive prepared in Example 3 of this invention. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] The raw materials used in the embodiments of this invention are shown below, and all reagents used are analytical grade.

[0029] Among them, the organic sulfonate was sodium polystyrene sulfonate, model XH-613, purchased from Shandong Xinghai Chemical Co., Ltd.; the polyamine polymer was polyethyleneimine, product number 767274, and the polymer was polyacrylamide, product number P821239, both purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; the surfactant was sodium lauryl ether sulfate.

[0030] Acrylamide (product number A800660) and acrylic acid (product number A800293) were both purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0031] Isobutylene alcohol, product number 208-161-0, was purchased from Ningbo Jinlai Chemical Co., Ltd. Carboxymethyl chitosan with a molecular weight of 60 kDa was purchased from Hefei Bomei Biotechnology Co., Ltd.

[0032] The nano-titanium dioxide particles have a diameter of 100 nm.

[0033] The silane coupling agent is KH570 (γ-methacryloyloxypropyltrimethoxysilane).

[0034] Example 1 A texturing additive for pyramid-patterned monocrystalline silicon wafers comprises the following raw materials in parts by weight: 1 part sodium polystyrene sulfonate, 1 part polyethyleneimine, 1 part polyacrylamide, 0.5 parts sodium lauryl ether sulfate, 0.2 parts composite additive, and 90 parts deionized water. A method for preparing a texturing additive for pyramid-textured monocrystalline silicon wafers includes the following preparation steps: Sodium polystyrene sulfonate, polyethyleneimine, polyacrylamide, sodium lauryl ether sulfate, composite additives and deionized water were mixed and stirred for 30 minutes at 20°C and 800 r / min to obtain a flocking additive.

[0035] The composite additive is prepared by the following steps: A1. Carboxymethyl chitosan was added to a 1% (w / w) aqueous solution of acetic acid and stirred until completely dissolved. KH570 and ethanol were added, and the mixture was stirred at 70°C for 30 min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70°C for 10 min to obtain double-bonded chitosan. The mass ratio of carboxymethyl chitosan, aqueous acetic acid, KH570, and ethanol was 2:30:1:80. A2. Add double-bonded chitosan to deionized water and stir at 40°C until completely dispersed. Add acrylamide, acrylic acid, and isobutylene alcohol, stir evenly, purge with nitrogen, add ammonium persulfate, and stir to react at 65°C for 4 hours. Cool to room temperature to obtain a viscous liquid. Place the viscous liquid in ethanol to form a precipitate. Collect the precipitate, wash it three times with ethanol, and dry it in a 50°C oven for 10 minutes to obtain a chitosan-based modifier. The mass ratio of double-bonded chitosan, deionized water, acrylamide, acrylic acid, isobutylene alcohol, and ammonium persulfate is 2:50:0.8:1:1.1:0.05. The mass ratio of viscous liquid to ethanol is 1:5; A3. Mix nano-titanium dioxide and deionized water, stir well, add 1 mol / L sodium hydroxide solution to adjust the pH to 9, then add tetraethyl orthosilicate and ethanol, stir at 50℃ for 1.5 h to form a gel, remove the gel, filter, wash three times with deionized water, and dry in a 70℃ oven for 10 min to obtain modified nano-titanium dioxide; the mass ratio of nano-titanium dioxide, deionized water, tetraethyl orthosilicate and ethanol is 1:45:2:90; A4. Add the chitosan-based modifier to deionized water and stir until homogeneous. Add the modified nano-titanium dioxide and ethylene glycol and stir until homogeneous. Add 1 mol / L hydrochloric acid to adjust the pH to 3.5. Stir and react at 70℃ for 2 hours. After filtration, wash three times with deionized water and dry in a 60℃ oven for 10 minutes to obtain the composite additive. The mass ratio of chitosan-based modifier, deionized water, modified nano-titanium dioxide and ethylene glycol is 2:50:1:0.8.

[0036] Example 2 A texturing additive for pyramid-textured monocrystalline silicon wafers comprises the following raw materials in parts by weight: 1.3 parts sodium polystyrene sulfonate, 1.5 parts polyethyleneimine, 1.5 parts polyacrylamide, 0.8 parts sodium lauryl ether sulfate, 0.4 parts composite additive, and 100 parts deionized water. A method for preparing a texturing additive for pyramid-textured monocrystalline silicon wafers includes the following preparation steps: Sodium polystyrene sulfonate, polyethyleneimine, polyacrylamide, sodium lauryl ether sulfate, composite additives and deionized water were mixed and stirred at 25°C and 1200 r / min for 45 min to obtain a flocking additive.

[0037] The composite additive is prepared by the following steps: A1. Carboxymethyl chitosan was added to a 1% (w / w) aqueous solution of acetic acid and stirred until completely dissolved. KH570 and ethanol were added, and the mixture was stirred at 70°C for 30 min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70°C for 10 min to obtain double-bonded chitosan. The mass ratio of carboxymethyl chitosan, aqueous acetic acid, KH570, and ethanol was 2.2:35:1.1:85. A2. Add double-bonded chitosan to deionized water and stir at 40°C until completely dispersed. Add acrylamide, acrylic acid, and isobutylene alcohol, stir evenly, purge with nitrogen, add ammonium persulfate, and stir to react at 68°C for 5 hours. Cool to room temperature to obtain a viscous liquid. Place the viscous liquid in ethanol to form a precipitate. Collect the precipitate, wash it three times with ethanol, and dry it in a 50°C oven for 10 minutes to obtain a chitosan-based modifier. The mass ratio of double-bonded chitosan, deionized water, acrylamide, acrylic acid, isobutylene alcohol, and ammonium persulfate is 2.3:55:0.9:1.1:1.2:0.08. The mass ratio of viscous liquid to ethanol is 1:6.5; A3. Mix nano-titanium dioxide and deionized water, stir well, add 1 mol / L sodium hydroxide solution to adjust the pH to 9, then add tetraethyl orthosilicate and ethanol, stir at 50℃ for 1.5 h to form a gel, remove the gel, filter, wash three times with deionized water, and dry in a 70℃ oven for 10 min to obtain modified nano-titanium dioxide; the mass ratio of nano-titanium dioxide, deionized water, tetraethyl orthosilicate and ethanol is 1.2:48:2.3:93; A4. Add the chitosan-based modifier to deionized water and stir until homogeneous. Add the modified nano-titanium dioxide and ethylene glycol and stir until homogeneous. Add 1 mol / L hydrochloric acid to adjust the pH to 3.5. Stir and react at 70℃ for 2 hours. After filtration, wash three times with deionized water and dry in a 60℃ oven for 10 minutes to obtain the composite additive. The mass ratio of chitosan-based modifier, deionized water, modified nano-titanium dioxide and ethylene glycol is 2.2:55:1.1:0.9.

[0038] Example 3 A texturing additive for pyramid-textured monocrystalline silicon wafers comprises the following raw materials in parts by weight: 1.5 parts sodium polystyrene sulfonate, 2 parts polyethyleneimine, 2 parts polyacrylamide, 1 part sodium lauryl ether sulfate, 0.5 parts composite additive, and 110 parts deionized water. A method for preparing a texturing additive for pyramid-textured monocrystalline silicon wafers includes the following preparation steps: Sodium polystyrene sulfonate, polyethyleneimine, polyacrylamide, sodium lauryl ether sulfate, composite additives, and deionized water were mixed and stirred at 30°C and 1500 r / min for 60 min to obtain a flocking additive.

[0039] The composite additive is prepared by the following steps: A1. Carboxymethyl chitosan was added to a 1% (w / w) aqueous solution of acetic acid and stirred until completely dissolved. KH570 and ethanol were added, and the mixture was stirred at 70°C for 30 min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70°C for 10 min to obtain double-bonded chitosan. The mass ratio of carboxymethyl chitosan, aqueous acetic acid, KH570, and ethanol was 2.4:40:1.2:90. A2. Add double-bonded chitosan to deionized water and stir at 40°C until completely dispersed. Add acrylamide, acrylic acid, and isobutylene alcohol, stir evenly, purge with nitrogen, add ammonium persulfate, and stir to react at 70°C for 6 hours. Cool to room temperature to obtain a viscous liquid. Place the viscous liquid in ethanol to form a precipitate. Collect the precipitate, wash it three times with ethanol, and dry it in a 50°C oven for 10 minutes to obtain a chitosan-based modifier. The mass ratio of double-bonded chitosan, deionized water, acrylamide, acrylic acid, isobutylene alcohol, and ammonium persulfate is 2.5:60:1:1.2:1.3:0.1. The mass ratio of viscous liquid to ethanol is 1:8; A3. Mix nano-titanium dioxide and deionized water, stir evenly, add 1 mol / L sodium hydroxide solution to adjust pH to 9, then add tetraethyl orthosilicate and ethanol, stir at 50℃ for 1.5 h to form a gel, remove the gel, filter, wash three times with deionized water, and dry in a 70℃ oven for 10 min to obtain modified nano-titanium dioxide; the mass ratio of nano-titanium dioxide, deionized water, tetraethyl orthosilicate and ethanol is 1.3:50:2.5:95; A4. Add the chitosan-based modifier to deionized water and stir until homogeneous. Add the modified nano-titanium dioxide and ethylene glycol and stir until homogeneous. Add 1 mol / L hydrochloric acid to adjust the pH to 3.5. Stir and react at 70℃ for 2 hours. After filtration, wash three times with deionized water and dry in a 60℃ oven for 10 minutes to obtain the composite additive. The mass ratio of chitosan-based modifier, deionized water, modified nano-titanium dioxide and ethylene glycol is 2.3:60:1.2:1.

[0040] Comparative Example 1 A texturing additive for pyramid-textured monocrystalline silicon wafers comprises the following raw materials in parts by weight: 1.5 parts sodium polystyrene sulfonate, 2 parts polyethyleneimine, 2 parts polyacrylamide, 1 part sodium lauryl ether sulfate, 0.5 parts composite additive, and 110 parts deionized water. A method for preparing a texturing additive for pyramid-textured monocrystalline silicon wafers includes the following preparation steps: Sodium polystyrene sulfonate, polyethyleneimine, polyacrylamide, sodium lauryl ether sulfate, composite additives, and deionized water were mixed and stirred at 30°C and 500 r / min for 60 min to obtain a flocking additive.

[0041] The composite additive is prepared by the following steps: A1. Carboxymethyl chitosan was added to deionized water and stirred at 40°C until completely dispersed. Acrylamide, acrylic acid, and isobutylene alcohol were added and stirred evenly. Nitrogen gas was introduced, and ammonium persulfate was added. The mixture was stirred at 70°C for 6 hours and cooled to room temperature to obtain a viscous liquid. The viscous liquid was placed in ethanol to form a precipitate. The precipitate was collected, washed three times with ethanol, and dried in an oven at 50°C for 10 minutes to obtain a chitosan-based modifier. The mass ratio of carboxymethyl chitosan, deionized water, acrylamide, acrylic acid, isobutylene alcohol, and ammonium persulfate was 2.5:60:1:1.2:1.3:0.1. The mass ratio of viscous liquid to ethanol is 1:8; A2. Nano-titanium dioxide and deionized water were mixed and stirred evenly. A 1 mol / L sodium hydroxide solution was added to adjust the pH to 9. Tetraethyl orthosilicate and ethanol were then added. The mixture was stirred at 50°C for 1.5 h to form a gel. The gel was removed, filtered, washed three times with deionized water, and dried in a 70°C oven for 10 min to obtain modified nano-titanium dioxide. The mass ratio of nano-titanium dioxide, deionized water, tetraethyl orthosilicate, and ethanol was 1.3:50:2.5:95. A3. Add the chitosan-based modifier to deionized water and stir until homogeneous. Add the modified nano-titanium dioxide and ethylene glycol and stir until homogeneous. Add 1 mol / L hydrochloric acid to adjust the pH to 3.5. Stir and react at 70℃ for 2 hours. After filtration, wash three times with deionized water and dry in a 60℃ oven for 10 minutes to obtain the composite additive. The mass ratio of chitosan-based modifier, deionized water, modified nano-titanium dioxide and ethylene glycol is 2.3:60:1.2:1.

[0042] Comparative Example 2 A texturing additive for pyramid-textured monocrystalline silicon wafers comprises the following raw materials in parts by weight: 1.5 parts sodium polystyrene sulfonate, 2 parts polyethyleneimine, 2 parts polyacrylamide, 1 part sodium lauryl ether sulfate, 0.5 parts composite additive, and 110 parts deionized water. A method for preparing a texturing additive for pyramid-textured monocrystalline silicon wafers includes the following preparation steps: Sodium polystyrene sulfonate, polyethyleneimine, polyacrylamide, sodium lauryl ether sulfate, composite additives, and deionized water were mixed and stirred at 30°C and 500 r / min for 60 min to obtain a flocking additive.

[0043] The composite additive is prepared by the following steps: A1. Carboxymethyl chitosan was added to a 1% (w / w) aqueous solution of acetic acid and stirred until completely dissolved. KH570 and ethanol were added, and the mixture was stirred at 70°C for 30 min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70°C for 10 min to obtain double-bonded chitosan. The mass ratio of carboxymethyl chitosan, aqueous acetic acid, KH570, and ethanol was 2.4:40:1.2:90. A2. Add double-bonded chitosan to deionized water and stir at 40°C until completely dispersed. Add acrylic acid and isobutylene alcohol, stir evenly, purge with nitrogen, add ammonium persulfate, and stir at 70°C for 6 hours. Cool to room temperature to obtain a viscous liquid. Place the viscous liquid in ethanol to form a precipitate. Collect the precipitate, wash it three times with ethanol, and dry it in a 50°C oven for 10 minutes to obtain a chitosan-based modifier. The mass ratio of double-bonded chitosan, deionized water, acrylic acid, isobutylene alcohol, and ammonium persulfate is 3.5:60:1.2:1.3:0.1. The mass ratio of viscous liquid to ethanol is 1:8; A3. Mix nano-titanium dioxide and deionized water, stir evenly, add 1 mol / L sodium hydroxide solution to adjust pH to 9, then add tetraethyl orthosilicate and ethanol, stir at 50℃ for 1.5 h to form a gel, remove the gel, filter, wash three times with deionized water, and dry in a 70℃ oven for 10 min to obtain modified nano-titanium dioxide; the mass ratio of nano-titanium dioxide, deionized water, tetraethyl orthosilicate and ethanol is 1.3:50:2.5:95; A4. Add the chitosan-based modifier to deionized water and stir until homogeneous. Add the modified nano-titanium dioxide and ethylene glycol and stir until homogeneous. Add 1 mol / L hydrochloric acid to adjust the pH to 3.5. Stir and react at 70℃ for 2 hours. After filtration, wash three times with deionized water and dry in a 60℃ oven for 10 minutes to obtain the composite additive. The mass ratio of chitosan-based modifier, deionized water, modified nano-titanium dioxide and ethylene glycol is 2.3:60:1.2:1.

[0044] Comparative Example 3 A texturing additive for pyramid-textured monocrystalline silicon wafers comprises the following raw materials in parts by weight: 1.5 parts sodium polystyrene sulfonate, 2 parts polyethyleneimine, 2 parts polyacrylamide, 1 part sodium lauryl ether sulfate, 0.5 parts composite additive, and 110 parts deionized water. A method for preparing a texturing additive for pyramid-textured monocrystalline silicon wafers includes the following preparation steps: Sodium polystyrene sulfonate, polyethyleneimine, polyacrylamide, sodium lauryl ether sulfate, composite additives, and deionized water were mixed and stirred at 30°C and 500 r / min for 60 min to obtain a flocking additive.

[0045] The composite additive is prepared by the following steps: A1. Carboxymethyl chitosan was added to a 1% (w / w) aqueous solution of acetic acid and stirred until completely dissolved. KH570 and ethanol were added, and the mixture was stirred at 70°C for 30 min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70°C for 10 min to obtain double-bonded chitosan. The mass ratio of carboxymethyl chitosan, aqueous acetic acid, KH570, and ethanol was 2.4:40:1.2:90. A2. Add double-bonded chitosan to deionized water and stir at 40°C until completely dispersed. Add acrylamide and isobutylene alcohol, stir evenly, purge with nitrogen, add ammonium persulfate, and stir at 70°C for 6 hours. Cool to room temperature to obtain a viscous liquid. Place the viscous liquid in ethanol to form a precipitate. Collect the precipitate, wash it three times with ethanol, and dry it in a 50°C oven for 10 minutes to obtain a chitosan-based modifier. The mass ratio of double-bonded chitosan, deionized water, acrylamide, isobutylene alcohol, and ammonium persulfate is 3.7:60:1:1.3:0.1. The mass ratio of viscous liquid to ethanol is 1:8; A3. Mix nano-titanium dioxide and deionized water, stir evenly, add 1 mol / L sodium hydroxide solution to adjust pH to 9, then add tetraethyl orthosilicate and ethanol, stir at 50℃ for 1.5 h to form a gel, remove the gel, filter, wash three times with deionized water, and dry in a 70℃ oven for 10 min to obtain modified nano-titanium dioxide; the mass ratio of nano-titanium dioxide, deionized water, tetraethyl orthosilicate and ethanol is 1.3:50:2.5:95; A4. Add the chitosan-based modifier to deionized water and stir until homogeneous. Add the modified nano-titanium dioxide and ethylene glycol and stir until homogeneous. Add 1 mol / L hydrochloric acid to adjust the pH to 3.5. Stir and react at 70℃ for 2 hours. After filtration, wash three times with deionized water and dry in a 60℃ oven for 10 minutes to obtain the composite additive. The mass ratio of chitosan-based modifier, deionized water, modified nano-titanium dioxide and ethylene glycol is 2.3:60:1.2:1.

[0046] Comparative Example 4 A texturing additive for pyramid-textured monocrystalline silicon wafers comprises the following raw materials in parts by weight: 1.5 parts sodium polystyrene sulfonate, 2 parts polyethyleneimine, 2 parts polyacrylamide, 1 part sodium lauryl ether sulfate, 0.5 parts composite additive, and 110 parts deionized water. A method for preparing a texturing additive for pyramid-textured monocrystalline silicon wafers includes the following preparation steps: Sodium polystyrene sulfonate, polyethyleneimine, polyacrylamide, sodium lauryl ether sulfate, composite additives, and deionized water were mixed and stirred at 30°C and 500 r / min for 60 min to obtain a flocking additive.

[0047] The composite additive is prepared by the following steps: A1. Carboxymethyl chitosan was added to a 1% (w / w) aqueous solution of acetic acid and stirred until completely dissolved. KH570 and ethanol were added, and the mixture was stirred at 70°C for 30 min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70°C for 10 min to obtain double-bonded chitosan. The mass ratio of carboxymethyl chitosan, aqueous acetic acid, KH570, and ethanol was 2.4:40:1.2:90. A2. Add double-bonded chitosan to deionized water and stir at 40°C until completely dispersed. Add acrylamide and acrylic acid, stir evenly, purge with nitrogen, add ammonium persulfate, and stir at 70°C for 6 hours. Cool to room temperature to obtain a viscous liquid. Place the viscous liquid in ethanol to form a precipitate. Collect the precipitate, wash it three times with ethanol, and dry it in a 50°C oven for 10 minutes to obtain a chitosan-based modifier. The mass ratio of double-bonded chitosan, deionized water, acrylamide, acrylic acid, and ammonium persulfate is 3.8:60:1:1.2:0.1. The mass ratio of viscous liquid to ethanol is 1:8; A3. Mix nano-titanium dioxide and deionized water, stir evenly, add 1 mol / L sodium hydroxide solution to adjust pH to 9, then add tetraethyl orthosilicate and ethanol, stir at 50℃ for 1.5 h to form a gel, remove the gel, filter, wash three times with deionized water, and dry in a 70℃ oven for 10 min to obtain modified nano-titanium dioxide; the mass ratio of nano-titanium dioxide, deionized water, tetraethyl orthosilicate and ethanol is 1.3:50:2.5:95; A4. Add the chitosan-based modifier to deionized water and stir until homogeneous. Add the modified nano-titanium dioxide and ethylene glycol and stir until homogeneous. Add 1 mol / L hydrochloric acid to adjust the pH to 3.5. Stir and react at 70℃ for 2 hours. After filtration, wash three times with deionized water and dry in a 60℃ oven for 10 minutes to obtain the composite additive. The mass ratio of chitosan-based modifier, deionized water, modified nano-titanium dioxide and ethylene glycol is 2.3:60:1.2:1.

[0048] Comparative Example 5 A texturing additive for pyramid-textured monocrystalline silicon wafers comprises the following raw materials in parts by weight: 1.5 parts sodium polystyrene sulfonate, 2 parts polyethyleneimine, 2 parts polyacrylamide, 1 part sodium lauryl ether sulfate, 0.5 parts composite additive, and 110 parts deionized water. A method for preparing a texturing additive for pyramid-textured monocrystalline silicon wafers includes the following preparation steps: Sodium polystyrene sulfonate, polyethyleneimine, polyacrylamide, sodium lauryl ether sulfate, composite additives, and deionized water were mixed and stirred at 30°C and 500 r / min for 60 min to obtain a flocking additive.

[0049] The composite additive is prepared by the following steps: A1. Carboxymethyl chitosan was added to a 1% (w / w) aqueous solution of acetic acid and stirred until completely dissolved. KH570 and ethanol were added, and the mixture was stirred at 70°C for 30 min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70°C for 10 min to obtain double-bonded chitosan. The mass ratio of carboxymethyl chitosan, aqueous acetic acid, KH570, and ethanol was 2.4:40:1.2:90. A2. Add double-bonded chitosan to deionized water and stir at 40°C until completely dispersed. Add acrylamide, acrylic acid, and isobutylene alcohol, stir evenly, purge with nitrogen, add ammonium persulfate, and stir to react at 70°C for 6 hours. Cool to room temperature to obtain a viscous liquid. Place the viscous liquid in ethanol to form a precipitate. Collect the precipitate, wash it three times with ethanol, and dry it in a 50°C oven for 10 minutes to obtain a chitosan-based modifier. The mass ratio of double-bonded chitosan, deionized water, acrylamide, acrylic acid, isobutylene alcohol, and ammonium persulfate is 2.5:60:1:1.2:1.3:0.1. The mass ratio of viscous liquid to ethanol is 1:8; A3. Add the chitosan-based modifier to deionized water and stir until homogeneous. Add nano-titanium dioxide and ethylene glycol and stir until homogeneous. Add 1 mol / L hydrochloric acid to adjust the pH to 3.5. Stir and react at 70℃ for 2 hours. After filtration, wash three times with deionized water and dry in a 60℃ oven for 10 minutes to obtain the composite additive. The mass ratio of chitosan-based modifier, deionized water, nano-titanium dioxide and ethylene glycol is 2.3:60:1.2:1.

[0050] Comparative Example 6 A texturing additive for pyramid-textured monocrystalline silicon wafers comprises the following raw materials in parts by weight: 1.5 parts sodium polystyrene sulfonate, 2 parts polyethyleneimine, 2 parts polyacrylamide, 1 part sodium lauryl ether sulfate, 0.5 parts composite additive, and 110 parts deionized water. A method for preparing a texturing additive for pyramid-textured monocrystalline silicon wafers includes the following preparation steps: Sodium polystyrene sulfonate, polyethyleneimine, polyacrylamide, sodium lauryl ether sulfate, composite additives, and deionized water were mixed and stirred at 30°C and 500 r / min for 60 min to obtain a flocking additive.

[0051] The composite additive is prepared by the following steps: A1. Carboxymethyl chitosan was added to a 1% (w / w) aqueous solution of acetic acid and stirred until completely dissolved. KH570 and ethanol were added, and the mixture was stirred at 70°C for 30 min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70°C for 10 min to obtain double-bonded chitosan. The mass ratio of carboxymethyl chitosan, aqueous acetic acid, KH570, and ethanol was 2.4:40:1.2:90. A2. Add double-bonded chitosan to deionized water and stir at 40°C until completely dispersed. Add acrylamide, acrylic acid, and isobutylene alcohol, stir evenly, purge with nitrogen, add ammonium persulfate, and stir to react at 70°C for 6 hours. Cool to room temperature to obtain a viscous liquid. Place the viscous liquid in ethanol to form a precipitate. Collect the precipitate, wash it three times with ethanol, and dry it in a 50°C oven for 10 minutes to obtain a chitosan-based modifier. The mass ratio of double-bonded chitosan, deionized water, acrylamide, acrylic acid, isobutylene alcohol, and ammonium persulfate is 2.5:60:1:1.2:1.3:0.1. The mass ratio of viscous liquid to ethanol is 1:8; A3. Mix nano-titanium dioxide and deionized water, stir evenly, add 1 mol / L sodium hydroxide solution to adjust pH to 9, then add tetraethyl orthosilicate and ethanol, stir at 50℃ for 1.5 h to form a gel, remove the gel, filter, wash three times with deionized water, and dry in a 70℃ oven for 10 min to obtain modified nano-titanium dioxide; the mass ratio of nano-titanium dioxide, deionized water, tetraethyl orthosilicate and ethanol is 1.3:50:2.5:95; A4. Add the chitosan-based modifier to deionized water and stir until homogeneous. Add the modified nano-titanium dioxide and stir until homogeneous. Add 1 mol / L hydrochloric acid to adjust the pH to 3.5. Stir and react at 70℃ for 2 hours. After filtration, wash three times with deionized water and dry in a 60℃ oven for 10 minutes to obtain the composite additive. The mass ratio of chitosan-based modifier, deionized water and modified nano-titanium dioxide is 2.3:60:2.2.

[0052] The performance of the fabrication additives prepared in Examples 1-3 and Comparative Examples 1-6 was tested.

[0053] The texturing additive, deionized water and sodium hydroxide of the monocrystalline silicon wafer prepared above were mixed in a mass ratio of 0.4:0.6:100 and stirred evenly at 82°C to obtain the texturing etching solution. The monocrystalline silicon wafer is immersed in a texturing etching solution and reacted at 82°C for 460 seconds. The monocrystalline silicon wafer is then removed and rinsed with deionized water and anhydrous ethanol for 30 seconds on each side. After drying, the texturized monocrystalline silicon wafer is obtained.

[0054] The reflectivity of the textured monocrystalline silicon wafer surface was tested using a standard 8-degree angle integrating reflectometer provided by Shanghai Fuxiang Optics Co., Ltd.

[0055] Silicon loss: The silicon loss (mg / dm³) is calculated by measuring the change in mass of the monocrystalline silicon wafer before and after texturing. 3 ).

[0056] The test results are shown in Table 1.

[0057] Table 1 Performance testing of the flocking additives prepared in Examples 1-3 and Comparative Examples 1-6 As can be seen from the data in Table 1, the texturing additives prepared in Examples 1-3 have a good texturing effect on monocrystalline silicon wafers, resulting in smaller, more uniformly distributed pyramids and lower reflectivity on the surface of the monocrystalline silicon wafers.

[0058] Comparative Example 1: A composite additive prepared by replacing double-bonded chitosan with carboxymethyl chitosan was added to the texturing additive to form a pyramidal textured surface on a monocrystalline silicon wafer. The reflectivity of the monocrystalline silicon wafer increased, demonstrating that the silane coupling agent grafted onto the carboxymethyl chitosan molecular chain imparts double bonds that can copolymerize with the carboxymethyl chitosan. This facilitates the introduction of a large number of hydroxyl, amino, and carboxyl functional groups onto the carboxymethyl chitosan molecular chain, improving the adsorption of the texturing additive on the surface of the monocrystalline silicon wafer. This effectively controls the surface corrosion rate of the monocrystalline silicon wafer, forming a uniformly textured pyramidal structure on the surface of the monocrystalline silicon wafer, significantly reducing the reflectivity of the monocrystalline silicon wafer, and improving the light absorption conversion efficiency of the monocrystalline silicon wafer.

[0059] Comparative Example 2, in which acrylamide was replaced by double-bonded chitosan, Comparative Example 3, in which acrylic acid was replaced by double-bonded chitosan, and Comparative Example 4, in which isobutylene alcohol was replaced by double-bonded chitosan, were used to form a pyramidal textured surface on monocrystalline silicon wafers. The reflectivity of the monocrystalline silicon wafers increased, demonstrating that acrylic acid and isobutylene alcohol carry a large number of carboxyl and hydroxyl groups. By introducing anionic groups, the alkali resistance of chitosan is improved, preventing the glycosidic bonds of chitosan from easily breaking under alkaline conditions, which would lead to polymer degradation and affect the texturing effect of the texturing additive. Acrylamide carries amine groups, which have weak cationic properties, and can enhance the adsorption performance of the texturing additive on the surface of monocrystalline silicon wafers under alkaline conditions.

[0060] Comparative Example 5 replaced the modified nano-titanium dioxide with a composite additive prepared from nano-titanium dioxide and added it to the texturing additive to form a pyramid textured surface on the monocrystalline silicon wafer. The reflectivity of the monocrystalline silicon wafer increased, proving that coating the surface of nano-titanium dioxide with a silicon dioxide layer has good light reflection performance, further reducing the reflectivity of the monocrystalline silicon wafer. Moreover, the modified nano-titanium dioxide formed can form a nanocomposite film on the surface of the monocrystalline silicon wafer, further increasing the surface roughness and scattering effect, more effectively reducing the surface reflectivity of the monocrystalline silicon wafer, and further improving the light absorption efficiency of the monocrystalline silicon cell.

[0061] Comparative Example 6 replaced ethylene glycol by mass with a composite additive prepared from modified nano-titanium dioxide and added it to the texturing additive to form a pyramidal textured surface on a monocrystalline silicon wafer. The reflectivity of the monocrystalline silicon wafer increased, demonstrating that the modified nano-titanium dioxide, dispersed in chitosan-based modifiers by ethylene glycol, avoids agglomeration of the modified nano-titanium dioxide in the texturing additive, thus preventing it from affecting the texturing effect of the additive. It also improves the adhesion of the modified nano-titanium dioxide to the surface of the monocrystalline silicon wafer, avoiding poor adhesion that would affect the structure of the nanocomposite film, thereby increasing the surface roughness and scattering effect.

[0062] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0063] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A texturing additive for pyramid-patterned monocrystalline silicon wafers, characterized in that, The raw materials include the following parts by weight: 1-1.5 parts organic sulfonate, 1-2 parts polyamine polymer, 1-2 parts polymer, 0.5-1 part surfactant, 0.2-0.5 parts composite additive, and 90-110 parts deionized water; The composite additive is obtained by synthesizing a silica layer on the surface of nano-titanium dioxide, and then reacting it with a chitosan-based modifier and ethylene glycol. The chitosan-based modifier is obtained by grafting carboxymethyl chitosan with a silane coupling agent and then reacting it with acrylic acid, acrylamide, and isobutylene alcohol.

2. The texturing additive for a pyramid-patterned monocrystalline silicon wafer according to claim 1, characterized in that, The composite additive is prepared by the following steps: A1. Carboxymethyl chitosan was added to an aqueous acetic acid solution and stirred until completely dissolved. Then, a silane coupling agent and ethanol were added, and the reaction was stirred until complete. After filtration, washing, and drying, double-bonded chitosan was obtained. A2. Add double-bonded chitosan to deionized water and stir until completely dispersed. Add acrylamide, acrylic acid, and isobutylene alcohol, stir evenly, purge with nitrogen, add ammonium persulfate, and stir to react at 65-70℃ for 4-6 hours. Cool to room temperature to obtain a viscous liquid. Place the viscous liquid in ethanol, collect the precipitate, wash and dry the precipitate to obtain chitosan-based modifier. A3. Mix nano-titanium dioxide and deionized water, stir evenly, add sodium hydroxide solution to adjust pH, add tetraethyl orthosilicate and ethanol, stir to react to form a gel, remove the gel, filter, wash and dry to obtain modified nano-titanium dioxide. A4. Add the chitosan-based modifier to deionized water and stir until homogeneous. Add the modified nano-titanium dioxide and ethylene glycol and stir until homogeneous. Add hydrochloric acid to adjust the pH and then stir to react. After filtration, washing, and drying, the composite additive is obtained.

3. The texturing additive for a pyramid-patterned monocrystalline silicon wafer according to claim 2, characterized in that, In step A1, the mass ratio of carboxymethyl chitosan, aqueous acetic acid, silane coupling agent and ethanol is (2-2.4):(30-40):(1-1.2):(80-90).

4. The texturing additive for a pyramid-patterned monocrystalline silicon wafer according to claim 2, characterized in that, In step A2, the mass ratio of the double-bonded chitosan, deionized water, acrylamide, acrylic acid, isobutylene alcohol, and ammonium persulfate is (2-2.5):(50-60):(0.8-1):(1-1.2):(1.1-1.3):(0.05-0.1). In step A2, the mass ratio of the viscous liquid to ethanol is 1:(5-8).

5. The texturing additive for a pyramid-patterned monocrystalline silicon wafer according to claim 2, characterized in that, In step A3, the mass ratio of nano-titanium dioxide, deionized water, tetraethyl orthosilicate and ethanol is (1-1.3):(45-50):(2-2.5):(90-95).

6. The texturing additive for a pyramid-patterned monocrystalline silicon wafer according to claim 2, characterized in that, In step A4, the mass ratio of the chitosan-based modifier, deionized water, modified nano-titanium dioxide, and ethylene glycol is (2-2.3):(50-60):(1-1.2):(0.8-1).

7. The texturing additive for a pyramid-patterned monocrystalline silicon wafer according to claim 1, characterized in that, The organic sulfonate is selected from any one of sodium polystyrene sulfonate, sodium polynaphthalene sulfonate, and acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer; The polyamine polymer is selected from polyethyleneimine or polyallylamine.

8. The texturing additive for a pyramid-patterned monocrystalline silicon wafer according to claim 1, characterized in that, The polymer is selected from polyacrylamide or polymaleic anhydride.

9. The texturing additive for a pyramid-patterned monocrystalline silicon wafer according to claim 1, characterized in that, The surfactant is selected from any one of sodium lauryl ether sulfate, sodium lauryl ether, sodium dodecyl sulfate, methyl oleate ethoxylate, and glycerol fatty acid ester sulfate.

10. A method for preparing a texturing additive for a pyramid-patterned monocrystalline silicon wafer as described in any one of claims 1-9, characterized in that, The preparation steps include the following: Organic sulfonate, polyamine polymer, polymer, surfactant, composite additive and deionized water are mixed and stirred for 30-60 minutes at 20-30℃ and 800-1500 r / min to obtain a flocking additive.

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