Crystalline silicon texturing agent, texturing method, textured monocrystalline silicon and solar cell

Abstract

The invention discloses a crystalline silicon texturing agent, a texturing method, textured monocrystalline silicon and a solar cell, and belongs to the technical field of photovoltaic materials. The texturing agent comprises 1%-10% of an etching agent, 1%-5% of a surface active agent, 0.1%-3% of acid, 0.1%-1.5% of a dispersing agent, 0.1%-0.5% of a sterilizing agent and the balance of water, wherein the total percentage is 100%. Wherein the etching agent is organic alkali. Inorganic alkali is replaced by organic alkali, so that metal ions in texturing are reduced, and the minority carrier lifetime of crystalline silicon is prolonged; the surface active agent is added, so that the textured surface is more uniform, and texturing reaction impurities are more quickly separated from the silicon surface; the weak acid is added, so that the reaction rate of OH <-> and Si can be slowed down, the formed pyramid structure is more regular, the pyramid size and arrangement are more uniform, the textured crystalline silicon is proper in surface roughness and high in light absorption rate, and the cell conversion efficiency is improved; and the texturing time is shortened, and the production cost is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of photovoltaic materials, and in particular to a crystalline silicon texturing agent, a texturing method, texturing single crystal silicon and a solar cell. Background Art

[0002] Photovoltaic silicon wafer texturing is an important step in the manufacturing process of solar cells. Its purpose is to increase the surface roughness of the silicon wafer, thereby increasing the light absorption rate and improving the conversion efficiency of the battery.

[0003] The texturing process of photovoltaic silicon wafers includes 1. Selecting silicon wafer materials: The texturing process usually uses single crystal silicon or multi-crystalline silicon wafers. These silicon wafers need to be cut and cleaned before texturing to ensure that the surface is clean and pollution-free. 2. Texturing methods: 2.1 Chemical etching: This is a common texturing method that removes a thin layer of silicon material on the surface of the silicon wafer through chemical reactions to form irregular textures. Commonly used texturing agents include alkaline solutions (such as sodium hydroxide or potassium hydroxide, which are mostly used in single crystal silicon texturing) and acidic solutions (such as a mixture of nitric acid and hydrofluoric acid, which is usually used in polycrystalline silicon texturing). 2.2 Dry etching: For example, plasma etching uses high-energy particles generated by plasma to directly impact the surface of the silicon wafer to form micron-sized pits, thereby increasing the surface roughness. 3. Cleaning and drying: The etched silicon wafer needs to be thoroughly cleaned to remove all chemical residues and then dried. 4. Inspection: The silicon wafer that has completed texturing needs to be tested for surface and performance to ensure that the surface roughness and structure meet the requirements, as well as the efficiency and quality standards of the battery.

[0004] The traditional chemical texturing method mainly relies on the alkali (KOH or NaOH) alcohol (isopropanol) system. However, this process has great defects. First, the texturing time is long, and the reaction generally takes 30-40 minutes. Secondly, the boiling point of isopropanol is relatively low at 82.4°C, which is close to the reaction temperature of 80°C, so isopropanol needs to be added continuously during the reaction process to maintain its concentration. Finally, due to the problem of inorganic alkali ionization, metal ions exist in the reaction solution. These metal ions will form a composite center, affecting the minority carrier lifetime of the single crystal silicon wafer, reducing the open circuit voltage and short circuit current of the single crystal silicon solar cell, and resulting in a decrease in the photoelectric conversion efficiency of the single crystal silicon solar cell. Summary of the invention

[0005] The main purpose of the present application is to provide a crystalline silicon texturing agent, a texturing method, texturing single crystal silicon and a solar cell, so as to solve the problems in the prior art that the texturing agent of the alkali-alcohol system for single crystal silicon wafers has a long texturing time, a poor texturing effect, and the metal ions generated during the texturing process may affect the life and electrical properties of the single crystal silicon wafers.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a crystalline silicon texturing agent is provided, which includes the following components in weight percentage: 1% to 10% of an etchant, 1% to 5% of a surfactant, 0.1% to 3% of an acid, 0.1% to 1.5% of a dispersant, 0.1% to 0.5% of a bactericide, and the remainder is water, totaling 100%; wherein the etchant is an organic base.

[0007] Furthermore, the weight percentage of the etchant is 5% to 10%, preferably 7% to 9%.

[0008] Furthermore, the weight percentage of the surfactant is 2% to 5%, preferably 3% to 5%.

[0009] Furthermore, the weight percentage of the acid is 0.5% to 3%, preferably 0.5% to 2%.

[0010] Furthermore, the weight percentage of the dispersant is 0.5% to 1.5%, preferably 0.7% to 1.5%.

[0011] Furthermore, the weight percentage of the fungicide is 0.2% to 0.5%, preferably 0.3% to 0.5%.

[0012] Furthermore, the pH of the organic base is >12.

[0013] Furthermore, the organic base is selected from at least one of a nitrogen-containing organic base, a phosphazene base, a quaternary ammonium base and an amide lithium compound.

[0014] Furthermore, the nitrogen-containing organic base is tetramethylguanidine.

[0015] Furthermore, the phosphazene base is a phosphazene ligand P4-tert-butyl.

[0016] Furthermore, the quaternary ammonium base is choline hydroxide and / or tetramethylammonium hydroxide.

[0017] Furthermore, the lithium amide compound is lithium disilazide.

[0018] Furthermore, the organic base is a nitrogen-containing organic base, or a mixed base of a phosphazene base and a quaternary ammonium base, or a mixed base of a nitrogen-containing organic base and a quaternary ammonium base, or a mixed base of a nitrogen-containing organic base and an amide lithium compound.

[0019] Furthermore, the organic base is tetramethylguanidine, or a mixed base of phosphazene ligand P4-tert-butyl and choline hydroxide, or a mixed base of tetramethylguanidine and choline hydroxide, or a mixed base of tetramethylguanidine and lithium disilazide.

[0020] Furthermore, in the mixed base of the phosphazene ligand P4-tert-butyl and choline hydroxide, the weight ratio of the phosphazene ligand P4-tert-butyl to choline hydroxide is (3-7):1; more preferably (3-6):1.

[0021] Furthermore, in the mixed base of tetramethylguanidine and choline hydroxide, the weight ratio of tetramethylguanidine to choline hydroxide is (2-5):1; more preferably (3-4):1.

[0022] Furthermore, in the mixed base of tetramethylguanidine and lithium disilazide, the weight ratio of tetramethylguanidine to lithium disilazide is (1-5):1; more preferably (2-4.5):1.

[0023] Furthermore, the surfactant is at least one of anionic surfactant, nonionic surfactant and amphoteric surfactant.

[0024] Furthermore, the surfactant is a mixture of anionic surfactant and nonionic surfactant, or a mixture of anionic surfactant, nonionic surfactant and amphoteric surfactant.

[0025] Further, the anionic surfactant includes sodium butylnaphthalene sulfonate and / or sodium butylphenylphenol sulfonate.

[0026] Furthermore, the nonionic surfactant includes alkyl polyglycoside and / or nonylphenol polyoxyethylene ether.

[0027] Further, the amphoteric surfactant includes alkyl hydroxyethyl alanine monosodium salt.

[0028] Furthermore, the surfactant is a mixture of alkyl polyglycoside and sodium butylnaphthalene sulfonate.

[0029] Furthermore, the weight ratio of the alkyl glycoside to sodium butyl naphthalene sulfonate is (1-2):1.

[0030] Furthermore, the surfactant is a mixture of sodium butylnaphthalene sulfonate, nonylphenol polyoxyethylene ether and alkyl hydroxyethyl alanine monosodium salt.

[0031] Furthermore, the weight ratio of sodium butylnaphthalene sulfonate, nonylphenol polyoxyethylene ether and alkyl hydroxyethyl alanine monosodium salt is (1-2):(0.5-1.5):(0.5-1.5).

[0032] Furthermore, the surfactant is a mixture of alkyl polyglycoside and nonylphenol polyoxyethylene ether.

[0033] Furthermore, the weight ratio of alkyl polyglycoside to nonylphenol polyoxyethylene ether is (0.5-1.5):1.

[0034] Furthermore, the surfactant is a mixture of alkyl polyglycoside, nonylphenol polyoxyethylene ether and sodium butylnaphthalene sulfonate.

[0035] Furthermore, the weight ratio of alkyl polyglycoside, nonylphenol polyoxyethylene ether and sodium butylnaphthalene sulfonate is 2:(1-1.5):(1-1.5).

[0036] Furthermore, the pH value of the acid is 2-6, preferably 4-6.

[0037] Furthermore, the acid is selected from at least one of formic acid, acetic acid, citric acid and phosphoric acid.

[0038] Furthermore, the acid is a mixed acid of formic acid and acetic acid.

[0039] Furthermore, the weight ratio of formic acid to acetic acid is (0.5-1.5):1.

[0040] Furthermore, the acid is citric acid.

[0041] Furthermore, the dispersant is selected from at least one of an ionic dispersant, a nonionic dispersant and an oily dispersant.

[0042] Furthermore, the ionic dispersant is a naphthalenesulfonic acid formaldehyde polymer sodium salt and / or a polycarboxylic acid sodium salt type dispersant.

[0043] Furthermore, the brand of the polycarboxylate sodium salt type dispersant is Nopco dispersant 5040.

[0044] Furthermore, the brand of the nonionic dispersant is Evonik dispersant 760W.

[0045] Furthermore, the brand of the oily dispersant is AKN-2350.

[0046] Furthermore, the dispersant is a mixture of AKN-2350 and Evonik dispersant 760W.

[0047] Furthermore, the weight ratio of AKN-2350 to Evonik dispersant 760W is (0.5-1.5):1.

[0048] Furthermore, the dispersant is a mixture of naphthalenesulfonic acid formaldehyde polymer sodium salt and Evonik dispersant 760W.

[0049] Furthermore, the weight ratio of naphthalenesulfonic acid formaldehyde polymer sodium salt to Evonik dispersant 760W is 1:(0.5-1).

[0050] Furthermore, the dispersant is a mixture of naphthalenesulfonic acid formaldehyde polymer sodium salt and Nopco dispersant 5040.

[0051] Furthermore, the weight ratio of naphthalenesulfonic acid formaldehyde polymer sodium salt to Nopco dispersant 5040 is (0.5-1):0.5.

[0052] Furthermore, the dispersant is naphthalenesulfonic acid formaldehyde polymer sodium salt.

[0053] Furthermore, the fungicide is selected from hydroquinone and / or isothiazolinone.

[0054] Furthermore, the catechol is o-catechol.

[0055] Furthermore, the isothiazolinone is 5-chloro-2-methyl-4-isothiazolin-3-one and / or 2-methyl-4-isothiazolin-3-one.

[0056] Furthermore, the fungicide is a mixture of catechol and 5-chloro-2-methyl-4-isothiazoline-3-one.

[0057] Furthermore, the weight ratio of catechol to isothiazolinone is (0.5-1.5):1.

[0058] Furthermore, the bactericide is catechol.

[0059] Furthermore, the water is deionized water.

[0060] According to a second aspect of the present application, a method for texturing crystalline silicon is provided, the method comprising the following steps:

[0061] Step S1: heating the texturing agent to 70-90° C.; wherein the texturing agent is the crystalline silicon texturing agent according to any one of claims 1 to 7;

[0062] Step S2: placing the crystalline silicon to be textured into a heated texturing agent and reacting for 300 to 500 seconds to obtain the textured crystalline silicon.

[0063] According to the third aspect of the present application, a texturized single crystal silicon is provided, and the texturized single crystal silicon is prepared by adopting the texturizing method mentioned above.

[0064] Furthermore, the average reflectivity of the textured single crystal silicon to sunlight is 9.5% to 12.6%.

[0065] Furthermore, the size of the pyramids in the textured surface of the single crystal silicon is 1.56 to 2.68 μm.

[0066] Furthermore, the number of pyramids on the surface of the textured single crystal silicon is 420 to 520 per mm. 2 .

[0067] According to a fourth aspect of the present application, a solar cell is provided, the solar cell comprising a silicon wafer; the silicon wafer is the above-mentioned textured crystalline silicon.

[0068] By applying the technical solution of the present application, a crystalline silicon texturing agent is provided, in which an organic alkali etchant is used to replace a traditional inorganic alkali etchant, so as to reduce metal ions in the texturing process, thereby increasing the minority carrier lifetime of crystalline silicon; adding a small amount of surfactant to the texturing agent can make the texturing surface more uniform, and allow impurities generated by the texturing reaction to detach from the silicon surface more quickly; adding a small amount of weak acid can slow down the reaction rate of hydroxide ions and Si on the silicon surface, so that the formed pyramid structure gradually becomes more regular, and the size and arrangement of the pyramids become more uniform, the surface roughness of the crystalline silicon after texturing is appropriate, the light absorption rate is high, and the battery conversion efficiency is improved; and the texturing time is shortened, thereby reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] The drawings constituting part of the present application are used to provide a further understanding of the present application. The exemplary embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0070] Figure 1 A schematic diagram of impurity distribution on the surface of a silicon wafer according to an embodiment of the present application is shown;

[0071] Figure 2 A scanning electron microscope (SEM) image of a single crystal silicon wafer after texturing using the texturing agent of Example 1 of the present application is shown;

[0072] Figure 3 A scanning electron microscope (SEM) image of a single crystal silicon wafer after texturing using the texturing agent of Comparative Example 1 of the present application is shown.

[0073] Reference numerals:

[0074] 1. Silicon wafer; 2. Oxide layer; 3. Solid particles; 4. Organic impurities; 5. Metal pollutants. DETAILED DESCRIPTION

[0075] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0076] As described in the background technology, the traditional chemical texturing method mainly adopts the alkali (KOH or NaOH) alcohol (isopropanol) system. This process has the disadvantage of long texturing time. Isopropanol has a low boiling point and is volatile, so it needs to be continuously replenished, which increases the production cost. In addition, the inorganic base will ionize metal ions in the reaction solution, which will affect the life and electrochemical properties of the single crystal silicon, resulting in poor texturing effect.

[0077] In response to the above problems, the present application provides a crystalline silicon texturing agent, comprising the following components, calculated in weight percentage: 1% to 10% etchant, 1% to 5% surfactant, 0.1% to 3% acid, 0.1% to 1.5% dispersant, 0.1% to 0.5% bactericide, and the remainder is water, totaling 100%; wherein the etchant is an organic base.

[0078] The role of the etchant in the texturing agent is to remove part of the material on the surface of the silicon wafer through a chemical reaction to form a velvet structure; organic bases are used instead of inorganic bases, and the organic bases will not ionize metal ions, thereby avoiding the introduction of metal ion contamination during the texturing process, thereby improving the minority carrier lifetime and electrochemical properties of crystalline silicon; the usage of the etchant is any value among 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any range between the two.

[0079] The role of the surfactant in the texturing agent is to effectively reduce the surface tension of the solution and enhance the penetration ability of the texturing agent. During the texturing process, the surfactant can allow the texturing agent to quickly penetrate into the contact area and form a lubricating film on the surface of the silicon wafer, thereby reducing friction and allowing the reaction products to quickly detach from the surface of the silicon wafer. Surfactants usually have a high boiling point and will not evaporate with the heating reaction, so no replenishment is required; the dosage of the surfactant is any value among 1%, 2%, 3%, 4%, 5%, or any range between the two.

[0080] The role of the acid in the texturing agent is to adjust the pH value of the texturing solution to ensure that the etching reaction is carried out in an appropriate acid-base environment; the acid can neutralize the hydroxide ions in the texturing process, reduce the hydroxide ions in the reaction, and slow down the reaction between Si and OH on the silicon wafer. - The pyramid structure formed by the corrosion reaction becomes more and more regular, and the suede surface is more uniform and has low reflectivity; some weak acids and compound surfactants may interact with each other when they exist at the same time, and jointly affect the properties of the solution and the state of the solid surface. The ions ionized by the weak acid may interact with the surfactant molecules, changing the distribution and arrangement of the surfactant in the solution, thereby affecting its wetting, dispersion, emulsification and other properties and optimizing the etching effect; the acid dosage is 0.1%, 0.5%, 1%, 1.5%, 2.0%, 2.5%, 3.0%, or any range between the two.

[0081] The function of the dispersant in the texturing agent is to prevent the aggregation of solid particles generated during the etching process and ensure the uniformity and stability of the texturing solution; the dispersant helps to improve the consistency and controllability of the etching effect; the dosage of the dispersant is any value among 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.5% or any range between the two.

[0082] The function of the bactericide in the texturing agent is to prevent the growth of bacteria and other microorganisms in the texturing solution, and ensure the cleanliness and stability of the texturing process; the bactericide helps to extend the service life of the texturing agent and improve the stability of the texturing effect; the dosage of the bactericide is any value among 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, or any range between the two.

[0083] The texturing agent of the present application is synergistically acted by an etchant, a surfactant, an acid, a dispersant and a bactericide. For example, a surfactant is a chemical substance with hydrophilic and hydrophobic properties. Its molecular structure characteristics enable it to form micelles in a solution, wrapping hydrophobic substances inside, thereby avoiding their precipitation and increasing solubility. In the texturing agent, the surfactant can reduce the surface tension of the solution, improve the wettability of the solution and the surface of the silicon wafer, and help the uniformity of the texturing reaction; the dispersant can ensure that the effective ingredients in the texturing agent are evenly distributed on the surface of the silicon wafer, thereby improving the texturing effect; the surfactant can reduce the surface tension of the solution, while the dispersant helps the dispersion of solid particles in the liquid; the combined action of the two can further enhance the wettability of the solution to the surface of the silicon wafer, making the texturing reaction more uniform; the dispersant can prevent the solid particles in the texturing agent from aggregating and precipitating, while the surfactant can wrap these particles in micelles to form a stable dispersion system; this synergistic effect helps to improve the utilization rate of the effective ingredients in the texturing agent, thereby improving the texturing effect; through the synergistic action of the surfactant and the dispersant, a more uniform and consistent pyramid velvet surface can be formed, improving the light trapping ability and photoelectric conversion efficiency of the silicon wafer. The above-mentioned texturing agent of the present application is more suitable for single crystal silicon bodies, such as single crystal silicon wafers.

[0084] In some embodiments, the texturing agent includes: 5% to 10% of an etchant, 2% to 5% of a surfactant, 0.5% to 3% of an acid, 0.5% to 1.5% of a dispersant, 0.2% to 0.5% of a bactericide, and the balance is water, totaling 100%; wherein the etchant is an organic base. By further optimizing the proportion of each component of the texturing agent, the texturing effect of crystalline silicon is improved, the velvet structure obtained is uniform, the number and arrangement of the pyramid structures are regular and uniform, the silicon wafer has low reflectivity, high light absorption rate, long life, and promotes battery conversion efficiency.

[0085] In some embodiments, the texturing agent includes: 7% to 9% of etching agent, 3% to 5% of surfactant, 0.5% to 2% of acid, 0.7% to 1.5% of dispersant, 0.3% to 0.5% of fungicide, and the balance is water, totaling 100%; wherein the etching agent is an organic base. By further optimizing the proportion of each component of the texturing agent, the average reflectivity of the obtained silicon wafer is lower, the light absorption rate is higher, the velvet size is smaller, the number of pyramids per square meter is more, and the service life is extended, and the battery conversion effect is improved.

[0086] In some embodiments, the texturing agent includes: 7% to 8% of etching agent, 3.5% to 4.5% of surfactant, 0.5% to 1% of acid, 0.8% to 1.2% of dispersant, 0.3% to 0.4% of fungicide, and the balance is water, totaling 100%; wherein the etching agent is an organic base. By further optimizing the proportion of each component of the texturing agent, the average reflectivity of the obtained silicon wafer is as low as 9.5% to 12.6%; the velvet size is smaller, such as 1.56 to 2.68 μm; the number of pyramids reaches 420 to 520 per mm 2 .

[0087] In some embodiments, the organic base is selected from at least one of a nitrogen-containing organic base, a phosphazene base, a quaternary ammonium base, and an amide lithium compound. For example, the organic base is a nitrogen-containing organic base, or a mixed base of a phosphazene base and a quaternary ammonium base, or a mixed base of a nitrogen-containing organic base and a quaternary ammonium base, or a mixed base of a nitrogen-containing organic base and an amide lithium compound. Among them, the nitrogen-containing organic base is tetramethylguanidine; the amide lithium compound is lithium disilazide (LiHMDS); the phosphazene base is the phosphazene ligand P4-tert-butyl (t-BuP 4 ); the quaternary ammonium base is selected from choline hydroxide and / or tetramethylammonium hydroxide; wherein the chemical structure of tetramethylguanidine is as follows:

[0088]

[0089] The above-mentioned organic base can effectively remove part of the material on the surface of the silicon wafer to form a velvet structure. The organic base is used to replace the inorganic base. The organic base will not ionize metal ions, thus avoiding the introduction of metal ion contamination during the velvet process, thereby improving the minority carrier lifetime and electrochemical performance of crystalline silicon.

[0090] In some embodiments, when a mixture of phosphazene ligand P4-tert-butyl and choline hydroxide is selected as an etchant, the weight ratio of phosphazene base to choline hydroxide is (3-7):1, further (3-6):1; further 5:1; and for example 3.5:1. Alternatively, when tetramethylguanidine and choline hydroxide are selected as etchants, the weight ratio of tetramethylguanidine to choline hydroxide is (2-5):1; further (3-4):1; further 3.5:1; or, when a mixture of tetramethylguanidine and lithium disilazide is selected as an etchant, the weight ratio of tetramethylguanidine to lithium disilazide is (1-5):1; further preferably (2-4.5):1; and further preferably 4:1. The use of the above-mentioned composite organic bases can improve the chemical reaction effect with silicon, which is conducive to the formation of a good velvet structure.

[0091] In some embodiments, the surfactant is at least one of anionic surfactant, nonionic surfactant and amphoteric surfactant; for example, a mixture of anionic surfactant and nonionic surfactant, or a mixture of anionic surfactant, nonionic surfactant and amphoteric surfactant. The above surfactants usually have a high boiling point and will not volatilize with the heating reaction, and do not need to be supplemented.

[0092] In some embodiments, the anionic surfactant includes sodium butylnaphthalene sulfonate and / or sodium butylphenylphenol sulfonate; the nonionic surfactant includes alkyl polyglycoside and / or nonylphenol polyoxyethylene ether; for example, the model of alkyl polyglycoside is APG0810. The amphoteric surfactant includes alkyl hydroxyethyl alanine monosodium salt, for example, the model is AMALF70. The above-mentioned surfactants can effectively reduce the surface tension of the solution and enhance the penetration of the solution on the silicon wafer.

[0093] In some embodiments, when the surfactant is a mixture of alkyl glycoside and sodium butyl naphthalene sulfonate, the weight ratio of alkyl glycoside to sodium butyl naphthalene sulfonate is (1-2):1, for example, 1.5:1. When the surfactant is a mixture of sodium butyl naphthalene sulfonate, nonylphenol polyoxyethylene ether, and alkyl hydroxyethyl alanine monosodium salt, the weight ratio of sodium butyl naphthalene sulfonate, nonylphenol polyoxyethylene ether, and alkyl hydroxyethyl alanine monosodium salt is (1-2):(0.5-1.5):(0.5-1.5), for example, 1.5:1:1. When the surfactant is a mixture of alkyl glycoside and nonylphenol polyoxyethylene ether, the weight ratio of alkyl glycoside to nonylphenol polyoxyethylene ether is (0.5-1.5):1, for example, 1:1. When the surfactant is a mixture of alkyl polyglycoside, nonylphenol polyoxyethylene ether and sodium butyl naphthalene sulfonate, the weight ratio of alkyl polyglycoside, nonylphenol polyoxyethylene ether and sodium butyl naphthalene sulfonate is 2:(1-1.5):(1-1.5). The use of the above-mentioned composite surfactant can effectively reduce the surface tension of the solution and enhance the penetration ability of the texturing agent. The surfactant can allow the texturing agent to quickly penetrate into the contact area during the texturing process, form a lubricating film on the surface of the silicon wafer, reduce friction, and quickly separate the reaction product from the surface of the silicon wafer. Compared with a single component, the mixture of two or more surfactants has better interfacial properties, such as lower surface tension, stronger emulsification, higher wettability and better viscosity.

[0094] In some embodiments, the pH value of the acid is 2 to 6; for example, 4 to 6. Selecting a weak acid within this range can adjust the pH value of the texturing solution to ensure that the etching reaction is carried out in an appropriate acid-base environment; the weak acid can neutralize the hydroxide ions in the texturing process, reduce the hydroxide ions in the reaction, and slow down the reaction between Si and OH on the silicon wafer. -The corrosion reaction forms a more and more regular pyramid structure, and the resulting velvet surface is more uniform and has a lower reflectivity. The weak acid can also work synergistically with other ingredients.

[0095] In some embodiments, the weak acid is selected from at least one of formic acid, acetic acid, citric acid and phosphoric acid. Furthermore, the weak acid is a mixed acid of formic acid and acetic acid, and the weight ratio of formic acid to acetic acid is (0.5-1.5):1, for example, 1:1. The weak acid can better neutralize the hydroxide ions in the texturing process, reduce the hydroxide ions in the reaction, and slow down the reaction between Si and OH on the silicon wafer. - The corrosion reaction makes the pyramid structure more and more regular, and the velvet surface is more uniform and has low reflectivity.

[0096] In some embodiments, the dispersant is selected from at least one of an ionic dispersant, a nonionic dispersant and an oily dispersant; wherein the ionic dispersant is a sodium salt of naphthalenesulfonic acid formaldehyde polymer and / or a sodium polycarboxylate type dispersant; the brand of the nonionic dispersant is Evonik dispersant 760W (Dispers760W, brand: Evonik; purchased from: Evonik Specialty Chemicals (Shanghai) Co., Ltd.); the brand of the sodium polycarboxylate type dispersant is Nopco dispersant 5040 (SN-DISPERSANT5040, brand: San Nopco; purchased from: San Nopco (Shanghai) Trading Co., Ltd.); the brand of the oily dispersant is AKN-2350 (brand XUHUAC, purchased from: Foshan Qianyou Chemical Co., Ltd.); for example, the brand of the dispersant is at least one of AKN-2350, Dispers760W and SN-DISPERSANT5040. The above dispersants can prevent the aggregation of solid particles generated during the etching process and ensure the uniformity and stability of the texturing solution.

[0097] In some embodiments, when the dispersant is a mixture of AKN-2350 and Dispers760W, the weight ratio of AKN-2350 to Dispers760W is (0.5-1.5):1, for example, 1:1. When the dispersant is a mixture of naphthalenesulfonic acid formaldehyde polymer sodium salt and Evonik dispersant 760W, the weight ratio of naphthalenesulfonic acid formaldehyde polymer sodium salt to Evonik dispersant 760W is 1:(0.5-1). When the dispersant is a mixture of naphthalenesulfonic acid formaldehyde polymer sodium salt and Nopco dispersant 5040, the weight ratio of naphthalenesulfonic acid formaldehyde polymer sodium salt to Nopco dispersant 5040 is (0.5-1):0.5. Or the dispersant is naphthalenesulfonic acid formaldehyde polymer sodium salt. Or the dispersant is SN-DISPERSANT5040. The use of the above dispersants can better prevent the aggregation of solid particles generated during the etching process, ensuring the uniformity and stability of the texturing solution; the above dispersants are more helpful in improving the consistency and controllability of the etching effect, which is conducive to the good formation of the velvet structure.

[0098] In some embodiments, the fungicide is selected from catechol and / or isothiazolinone; further, the catechol is catechol; further, the isothiazolinone is 5-chloro-2-methyl-4-isothiazoline-3-one (CMI) and / or 2-methyl-4-isothiazoline-3-one (MI). When the fungicide is a mixture of catechol and 5-chloro-2-methyl-4-isothiazoline-3-one, the weight ratio of catechol to 5-chloro-2-methyl-4-isothiazoline-3-one is (0.5-1.5):1, for example, 1:1; or, the fungicide is catechol; or the fungicide is 5-chloro-2-methyl-4-isothiazoline-3-one. Water is deionized water.

[0099] In some embodiments, the texturing agent includes: 7% to 8% of an etchant, 3.5% to 4.5% of a surfactant, 0.5% to 1% of an acid, 0.8% to 1.2% of a dispersant, 0.3% to 0.4% of a bactericide, and the remainder is water, which totals 100%; wherein the etchant is tetramethylguanidine, or a mixed base of a phosphazene ligand P4-tert-butyl and choline hydroxide, or a mixed base of tetramethylguanidine and choline hydroxide, or a mixed base of tetramethylguanidine and disilazide lithium; the surfactant is a mixture of an alkyl glucoside and sodium butyl naphthalene sulfonate, or sodium butyl naphthalene sulfonate, nonylphenol polyoxyethylene ether, and alkyl hydroxyethyl propylene glycol. The present invention relates to a mixture of monosodium salt of amino acid, or a mixture of alkyl glucoside and nonylphenol polyoxyethylene ether; or a mixture of alkyl glucoside, nonylphenol polyoxyethylene ether and sodium butyl naphthalene sulfonate; the acid is citric acid, or acetic acid, or a mixture of formic acid and acetic acid; the dispersant is sodium salt of naphthalenesulfonate formaldehyde polymer, or a mixture of AKN-2350 and Evonik dispersant 760W; or a mixture of sodium salt of naphthalenesulfonate formaldehyde polymer and Evonik dispersant 760W; or a mixture of sodium salt of naphthalenesulfonate formaldehyde polymer and Nopco dispersant 5040; the bactericide is hydroquinone and / or isothiazolinone, and the water is deionized water.

[0100] In some embodiments, the texturing agent includes: 7% to 8% of an etchant, 3.5% to 4.5% of a surfactant, 0.5% to 1% of an acid, 0.8% to 1.2% of a dispersant, 0.3% to 0.4% of a bactericide, and the remainder is water, which is 100% in total; wherein the etchant is tetramethylguanidine, or a mixed base of a phosphazene ligand P4-tert-butyl and choline hydroxide, the weight ratio of the two being (3 to 4): 1; or a mixture of tetramethylguanidine and choline hydroxide, the weight ratio of the two being (1.5 to 2): 1; or a mixed base of tetramethylguanidine and lithium disilazide, the weight ratio of the two is (1-3):1; the surfactant is a mixture of alkyl polyglucosides and sodium butyl naphthalene sulfonate, the weight ratio of the two is (1-2):1, or a mixture of sodium butyl naphthalene sulfonate, nonylphenol polyoxyethylene ether and alkyl hydroxyethyl alanine monosodium salt, the weight ratio of the three is (1-2):(0.5-1.5):(0.5-1.5), or a mixture of alkyl polyglucosides and nonylphenol polyoxyethylene ether, the weight ratio of the two is (0. 5~1.5):1; or a mixture of alkyl polyglycoside, nonylphenol polyoxyethylene ether and sodium butyl naphthalene sulfonate, the weight ratio of the three is 2:(1~1.5):(1~1.5); the acid is citric acid, or acetic acid, or a mixture of formic acid and acetic acid, the weight ratio of the two is (0.5~1.5):1; the dispersant is naphthalenesulfonic acid formaldehyde polymer sodium salt, or a mixture of AKN-2350 and Dispers760W, the weight ratio of the two is (0.5~1.5):1, or S N-DISPERSANT5040; or a mixture of sodium salt of naphthalenesulfonic acid formaldehyde polymer and Dispers760W, the weight ratio of the two is 1:(0.5~1); or a mixture of sodium salt of naphthalenesulfonic acid formaldehyde polymer and Nopco dispersant 5040, the weight ratio of the two is (0.5~1):0.5; the bactericide is a mixture of catechol and 5-chloro-2-methyl-4-isothiazoline-3-one, the weight ratio of the two is (0.5~1.5):1, and the water is deionized water. The use of the texturing agent with the above ratio has a better texturing effect, and the average reflectivity of the obtained silicon wafer is as low as 9.5%~11.3%; the velvet size is smaller, such as 1.56~2.51μm; the number of pyramids reaches 430~520 / mm 2 .

[0101] In some embodiments, the texturing agent formula is: 8% tetramethylguanidine, 3% alkyl glycoside APG0810, 2% sodium butyl naphthalene sulfonate, 0.5% citric acid, 1% sodium naphthalene sulfonate formaldehyde polymer, 0.3% catechol, and the balance is deionized water, totaling 100%. The average reflectivity of the texturing single crystal silicon wafer prepared by the texturing agent is 9.57%, the diameter of the velvet pyramid is 1.89μm, and the number of pyramids is 491 / mm 2 , good velvet making effect, pyramid structure, uniform quantity and regular arrangement.

[0102] In some embodiments, the texturing agent formula is: phosphazene base t-BuP 4 7%, choline hydroxide 2%, sodium butyl naphthalene sulfonate 1.5%, nonylphenol polyoxyethylene ether 1%, alkyl hydroxyethyl alanine monosodium salt AMALF70 1%, formic acid 0.5%, acetic acid 0.5%, AKN-2350 0.5%, Dispers760W 0.5%, 5-chloro-2-methyl-4-isothiazoline-3-one 0.5%, the balance is deionized water, a total of 100%. The average reflectivity of the textured single crystal silicon wafer prepared by the texturing agent is 10.35%, the velvet pyramid size is 1.87μm, and the number of pyramids is 438 / mm 2 , good velvet making effect, pyramid structure, uniform quantity and regular arrangement.

[0103] In some embodiments, the texturing agent formula is: 7% tetramethylguanidine, 2% choline hydroxide, 1% alkyl sugar APG0810, 1% nonylphenol polyoxyethylene ether, 1% acetic acid, 0.7% SN-DISPERSANT5040, 0.2% catechol, 0.2% 5-chloro-2-methyl-4-isothiazoline-3-one, and the balance is deionized water, totaling 100%. The average reflectivity of the texturing single crystal silicon wafer prepared by the texturing agent is 11.23%, the diameter of the velvet pyramid is 2.51μm, and the number of pyramids is 455 / mm 2 , good velvet making effect, pyramid structure, uniform quantity and regular arrangement.

[0104] The preparation method of the crystalline silicon texturing agent of the present application comprises: weighing the above components in order according to the component ratio, adding them into deionized water at 70-85°C and stirring them for 2-3 hours to obtain the above texturing agent; further, adding each component into deionized water at 80°C and stirring them for 3 hours. The preparation method of the above texturing agent is simple and easy to operate.

[0105] According to a second aspect of the present application, a method for texturing crystalline silicon is provided, the method comprising the following steps:

[0106] Step S1: heating the texturing agent to 70-90° C.; wherein the texturing agent is the above-mentioned crystalline silicon texturing agent;

[0107] Step S2: placing the crystalline silicon to be textured into a heated texturing agent and reacting for 300 to 500 seconds to obtain the textured crystalline silicon.

[0108] In some embodiments, a texturing agent for monocrystalline silicon is poured into a texturing tank (the content of the texturing agent in the tank is about 2% to 10%, preferably 5%. 2.5L of texturing agent is added, and the total volume of the tank is about 50L). After all the reagents are added, the liquid in the texturing tank is heated to 70 to 90°C (preferably 80°C). After heating to the set temperature, the monocrystalline silicon wafer is placed in the texturing tank to react for 300s to 500s (preferably 400s). After the reaction is completed, it is placed in a rinsing tank for cleaning. After cleaning, it is placed in a slow pulling tank to remove residual watermarks and then placed in an air drying tank for drying. The above texturing method is simple and easy to operate.

[0109] The texturing principle of the present application is: when a single crystal silicon wafer is corroded in an alkaline solution within a certain concentration range, it is anisotropic, and the corrosion rate on different crystal directions is different. Using this principle, a single crystal silicon wafer with a specific crystal direction is placed in an alkaline solution for corrosion, and many tiny pyramid-like appearances can be produced on the surface of the silicon wafer. This process is called single crystal alkali texturing. The size of the pyramids and the uniformity of their arrangement are important parameters for characterizing the texturing effect.

[0110] According to the third aspect of the present application, a textured single crystal silicon is provided, and the textured crystalline silicon is prepared by the above-mentioned textured method. Furthermore, the average reflectivity of the above-mentioned textured crystalline silicon to sunlight is 9.5% to 12.6%; the diameter of the textured surface of the textured crystalline silicon (i.e., the height and base width of the pyramid) is 1.56 to 2.68 μm; the number of pyramids on the surface of the textured crystalline silicon is 420 to 520 per mm 2 The textured single crystal silicon is a textured single crystal silicon wafer. The size and arrangement of the pyramids on the textured crystal silicon surface provided by the present application are more uniform, the whole is regular, the light absorption rate is high, and the photoelectric conversion efficiency can be improved when used in batteries.

[0111] According to a fourth aspect of the present application, a solar cell is provided. The solar cell includes a silicon wafer; the silicon wafer is the above-mentioned textured single crystal silicon.

[0112] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0113] All raw materials used in the examples of this application are prior art and can be purchased commercially.

[0114] Dispers760W source: brand is Evonik; purchased from: Evonik Specialty Chemicals (Shanghai) Co., Ltd.;

[0115] SN-DISPERSANT5040 Source: Brand is San Nopco; purchased from: San Nopco (Shanghai) Trading Co., Ltd.;

[0116] Source of AKN-2350: The brand is XUHUAC, purchased from: Foshan Qianyou Chemical Co., Ltd.

[0117] Method and equipment for detecting reflectivity of single crystal silicon wafers: 1. Select the detection area; 2. Use RTIS velvet reflectivity tester (brand: Menon Photovoltaic) to scan the detection area to obtain a three-dimensional image of the detection area; 3. Then use image processing software (such as MATLAB) to process the obtained three-dimensional image; 4. Calculate the reflectivity.

[0118] Example 1

[0119] Texturing agent formula: by weight percentage, tetramethylguanidine 8%, alkyl polyglycoside (APG0810) 3%, sodium butylnaphthalenesulfonate 2%, citric acid 0.5%, naphthalenesulfonic acid formaldehyde polymer sodium salt 1%, catechol 0.3%, the balance is deionized water, a total of 100%; see Table 1.

[0120] Preparation method of the texturing agent: add each component into deionized water at 80° C. and stir thoroughly for 3 hours to obtain the texturing agent.

[0121] Texturing process: Contaminants on the surface of single crystal silicon wafers such as Figure 1 As shown (silicon wafer 1, oxide layer 2, solid particles 3, organic impurities 4, pollutants 5), clean it before texturing to ensure that the surface is clean and pollution-free; take 2.5L of texturing agent and pour it into the texturing tank to fill it with deionized water (about 45L), heat the liquid in the texturing tank to 80℃, put the single crystal silicon wafer packaged in the flower basket into the texturing tank for texturing reaction, take out the silicon wafer after 400s of reaction and put it into the rinsing tank for cleaning, put it into the slow pulling tank to remove the residual watermark after cleaning, and then put it into the air drying tank to dry, and obtain the texturized single crystal silicon wafer; detect the morphology and performance (take 3 pieces in each group to measure the average value), as shown Figure 2 And as shown in Table 2.

[0122] Example 2

[0123] The difference between Example 2 and Example 1 is that the texturing agent formula is shown in Table 1, the texturing reaction time is 300s, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0124] Example 3

[0125] The difference between Example 3 and Example 1 is that the texturing agent formula is shown in Table 1, the texturing reaction time is 350s, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0126] Example 4

[0127] The difference between Example 4 and Example 1 is that the texturing agent formula is shown in Table 1, the texturing reaction time is 400s, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0128] Example 5

[0129] The difference between Example 5 and Example 1 is that the texturing agent formula is shown in Table 1, the texturing reaction time is 450s, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0130] Example 6

[0131] The difference between Example 6 and Example 1 is that the texturing agent formula is shown in Table 1, the texturing reaction time is 500s, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0132] Example 7

[0133] The difference between Example 7 and Example 1 is that the texturing agent formula is shown in Table 1, the texturing reaction time is 400s, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0134] Example 8

[0135] The difference between Example 8 and Example 1 is that the weight percentage of tetramethylguanidine in the texturing agent formula is 7%. The specific formula is shown in Table 1, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0136] Example 9

[0137] The difference between Example 9 and Example 1 is that the weight percentage of tetramethylguanidine in the texturing agent formula is 9%. The specific formula is shown in Table 1, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0138] Example 10

[0139] The difference between Example 10 and Example 1 is that the weight percentage of tetramethylguanidine in the texturing agent formula is 3%. The specific formula is shown in Table 1, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0140] Embodiment 11

[0141] The difference between Example 11 and Example 1 is that the total weight percentage of the surfactant in the texturing agent formula is 3%. The specific formula is shown in Table 1, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0142] Example 12

[0143] The difference between Example 12 and Example 1 is that the total weight percentage of surfactant in the texturing agent formula is 1%. The specific formula is shown in Table 1, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0144] Example 13

[0145] The difference between Example 13 and Example 1 is that the weight percentage of citric acid in the texturing agent formula is 1%. The specific formula is shown in Table 1, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0146] Embodiment 14

[0147] The difference between Example 14 and Example 1 is that the weight percentage of citric acid in the texturing agent formula is 2%. The specific formula is shown in Table 1, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0148] Embodiment 15

[0149] The difference between Example 15 and Example 1 is that the weight percentage of naphthalenesulfonic acid formaldehyde polymer sodium salt in the texturing agent formula is 0.7%. The specific formula is shown in Table 1, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0150] Example 16

[0151] The difference between Example 16 and Example 1 is that the weight percentage of naphthalenesulfonic acid formaldehyde polymer sodium salt in the texturing agent formula is 1.5%. The specific formula is shown in Table 1, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0152] Embodiment 17

[0153] The difference between Example 17 and Example 1 is that the weight percentage of catechol in the texturing agent formula is 0.2%. The specific formula is shown in Table 1, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0154] Embodiment 18

[0155] The difference between Example 18 and Example 1 is that the weight percentage of catechol in the texturing agent formula is 0.5%. The specific formula is shown in Table 1, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0156] Embodiment 19

[0157] The difference between Example 19 and Example 1 is that the tetramethylguanidine in the texturing agent formula is replaced by phosphazene base t-BuP 4 The specific formula is shown in Table 1, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0158] Embodiment 20

[0159] The difference between Example 20 and Example 1 is that sodium butylnaphthalene sulfonate in the texturing agent formula is replaced by nonylphenol polyoxyethylene ether. The specific formula is shown in Table 1, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0160] Embodiment 21

[0161] The difference between Example 21 and Example 1 is that the citric acid in the texturing agent formula is replaced by formic acid + acetic acid. The specific formula is shown in Table 1, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0162] Embodiment 22

[0163] The difference between Example 22 and Example 1 is that the sodium salt of naphthalenesulfonic acid formaldehyde polymer in the texturing agent formula is replaced by AKN-2350. The specific formula is shown in Table 1, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0164] Embodiment 23

[0165] The difference between Example 23 and Example 1 is that catechol in the texturing agent formula is replaced by 5-chloro-2-methyl-4-isothiazoline-3-one. The specific formula is shown in Table 1, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0166] Comparative Example 1

[0167] The difference between Comparative Example 1 and Example 1 is that the texturing agent is an inorganic base, the specific formula is shown in Table 1, the texturing reaction time is 1800s, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0168] Comparative Example 2

[0169] The difference between Comparative Example 2 and Example 1 is that the texturing agent is an inorganic base, the specific formula is shown in Table 1, the texturing reaction time is 2000s, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0170] Comparative Example 3

[0171] The difference between Comparative Example 3 and Example 1 is that the texturing agent formula is shown in Table 1, the texturing reaction time is 400s, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0172] Comparative Example 4

[0173] The difference between Comparative Example 4 and Example 1 is that the texturing agent formula is shown in Table 1, the texturing reaction time is 400s, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0174] Comparative Example 5

[0175] The difference between Comparative Example 5 and Example 1 is that the texturing agent formula is shown in Table 1, the texturing reaction time is 450s, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0176] Comparative Example 6

[0177] The difference between Comparative Example 6 and Example 1 is that the texturing agent formula is shown in Table 1, the texturing reaction time is 450s, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0178] Comparative Example 7

[0179] The difference between Comparative Example 7 and Example 1 is that the texturing agent formula is shown in Table 1, the texturing reaction time is 500s, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0180] Comparative Example 8

[0181] The difference between Comparative Example 8 and Example 1 is that the texturing agent formula is shown in Table 1, the texturing reaction time is 500s, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0182] Comparative Example 9

[0183] The difference between Comparative Example 9 and Example 1 is that the texturing agent formula is shown in Table 1, the texturing reaction time is 600s, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0184] Comparative Example 10

[0185] The difference between Comparative Example 10 and Example 1 is that the texturing agent formula is shown in Table 1, the texturing reaction time is 550s, and the morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0186] Comparative Example 11

[0187] The difference between Comparative Example 11 and Example 1 is that the texturing agent does not contain a surfactant. The specific formula is shown in Table 1. The texturing reaction time is 600s. The morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0188] Comparative Example 12

[0189] The difference between Comparative Example 12 and Example 1 is that the texturing agent does not contain weak acid. The specific formula is shown in Table 1. The texturing reaction time is 550s. The morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0190] Comparative Example 13

[0191] The difference between Comparative Example 13 and Example 1 is that the texturing agent does not contain a dispersant. The specific formula is shown in Table 1. The texturing reaction time is 600s. The morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0192] Comparative Example 14

[0193] The difference between Comparative Example 14 and Example 1 is that the texturing agent does not contain a bactericide. The specific formula is shown in Table 1. The texturing reaction time is 550s. The morphology and performance of the single crystal silicon wafer are shown in Table 2.

[0194] Table 1

[0195]

[0196]

[0197]

[0198]

[0199] Table 2

[0200]

[0201]

[0202] The test results in Table 2 show that the average reflectivity of the crystalline silicon prepared by the texturing agent of Examples 1 to 23 of the present application is 9.5% to 12.6%; the size of the pyramids of the texturing crystalline silicon is 1.56 to 2.68 μm; the number of pyramids on the surface of the texturing crystalline silicon is 420 to 520 per mm 2 ;by Figure 2 The SEM image of the texturized single-crystal silicon wafer is a representative example, which shows that the pyramids on the texturized single-crystal silicon surface are of uniform size and arranged more evenly and regularly, with high light absorption rate, which can improve the photoelectric conversion efficiency when used in batteries.

[0203] by Figure 3 The SEM image of the texturized single crystal silicon wafer is representative, showing that the pyramids on the texturized crystal silicon surface of Comparative Example 1 and Comparative Example 2 are obviously of different sizes and unevenly arranged, with a reflectivity of more than 13.5%. The pyramid diameter is about 3.62μm, and the number of pyramids is more than 170 less than that of the embodiment of the present application. The overall texturizing effect is poor, and the structure is not conducive to light absorption.

[0204] In Comparative Examples 3 to 10, the proportion of each component is too large or too small, and the texturing effect is not as good as that in the embodiment; for example, the reflectivity is too high, the pyramid size is too large and of different sizes, the regularity is poor, the number of pyramids is small, and the structure is not conducive to light absorption; this shows that when the proportion of each component in the texturing agent formula designed in the present application is within a specific range, the synergistic effect between multiple components can be improved, which is more conducive to obtaining a texturing agent with better texturing effect.

[0205] The texturing agent formulas of Comparative Examples 11 to 14 each lack one component, and their texturing effects are also worse than those of the embodiments of the present application; for example, the reflectivity is relatively high, the pyramid sizes are relatively large and of varying sizes, the regularity is relatively poor, the number of pyramids is relatively small, and the structure is not conducive to light absorption; this indicates that each component in the texturing agent formula designed in the present application is indispensable, and multiple components play their respective roles with better synergistic effects, which can ensure that the crystalline silicon texturing agent can efficiently and evenly form a velvet structure on the surface of the silicon wafer, thereby improving the light absorption efficiency and conversion efficiency of solar cells.

[0206] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those described herein, for example.

[0207] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A crystalline silicon texturing agent, characterized in that: The texturing agent comprises the following components in terms of weight percentage: 1% to 10% of etching agent, 1% to 5% of surfactant, 0.1% to 3% of acid, 0.1% to 1.5% of dispersant, 0.1% to 0.5% of bactericide, and the balance is water, which is 100% in total; wherein the etching agent is an organic base.

2. The crystalline silicon texturing agent according to claim 1, characterized in that: The weight percentage of the etching agent is 5% to 10%, preferably 7% to 9%; And / or, the weight percentage of the surfactant is 2% to 5%, preferably 3% to 5%; And / or, the weight percentage of the acid is 0.5% to 3%, preferably 0.5% to 2%; And / or, the weight percentage of the dispersant is 0.5% to 1.5%, preferably 0.7% to 1.5%; And / or, the weight percentage of the bactericide is 0.2% to 0.5%, preferably 0.3% to 0.5%.

3. The crystalline silicon texturing agent according to claim 1 or 2, characterized in that: The pH of the organic base is>12; Preferably, the organic base is selected from at least one of a nitrogen-containing organic base, a phosphazene base, a quaternary ammonium base and an amide lithium compound; Preferably, the nitrogen-containing organic base is tetramethylguanidine; Preferably, the phosphazene base is a phosphazene ligand P4-tert-butyl; Preferably, the quaternary ammonium base is choline hydroxide and / or tetramethylammonium hydroxide; Preferably, the lithium amide compound is lithium disilazide; Preferably, the organic base is a nitrogen-containing organic base, or a mixed base of the phosphazene base and the quaternary ammonium base, or a mixed base of the nitrogen-containing organic base and the quaternary ammonium base, or a mixed base of the nitrogen-containing organic base and the amide lithium compound; Preferably, the organic base is the tetramethylguanidine, or a mixed base of the phosphazene ligand P4-tert-butyl and the choline hydroxide, or a mixed base of the tetramethylguanidine and the choline hydroxide, or a mixed base of the tetramethylguanidine and the disilazide lithium; Preferably, in the mixed base of the phosphazene ligand P4-tert-butyl and the choline hydroxide, the weight ratio of the phosphazene base to the choline hydroxide is (3-7):1; more preferably (3-6):1; Preferably, in the mixed base of tetramethylguanidine and choline hydroxide, the weight ratio of tetramethylguanidine to choline hydroxide is (2-5):1; more preferably (3-4):1; Preferably, in the mixed base of tetramethylguanidine and lithium disilazide, the weight ratio of tetramethylguanidine to lithium disilazide is (1-5):1; more preferably (2-4.5):

1.

4. The crystalline silicon texturing agent according to any one of claims 1 to 3, characterized in that: The surfactant is at least one of anionic surfactant, nonionic surfactant and amphoteric surfactant; Preferably, the surfactant is a mixture of the anionic surfactant and the nonionic surfactant, or a mixture of the anionic surfactant, the nonionic surfactant and the amphoteric surfactant; Preferably, the anionic surfactant comprises sodium butylnaphthalene sulfonate and / or sodium butylphenylphenol sulfonate; Preferably, the nonionic surfactant comprises alkyl polyglycoside and / or nonylphenol polyoxyethylene ether; Preferably, the amphoteric surfactant comprises alkyl hydroxyethyl alanine monosodium salt; Preferably, the surfactant is a mixture of the alkyl polyglycoside and the sodium butyl naphthalene sulfonate; more preferably, the weight ratio of the alkyl polyglycoside to the sodium butyl naphthalene sulfonate is (1-2):1; Preferably, the surfactant is a mixture of the sodium butyl naphthalene sulfonate, the nonylphenol polyoxyethylene ether and the alkyl hydroxyethyl alanine monosodium salt; more preferably, the weight ratio of the sodium butyl naphthalene sulfonate, the nonylphenol polyoxyethylene ether and the alkyl hydroxyethyl alanine monosodium salt is (1-2):(0.5-1.5):(0.5-1.5); Preferably, the surfactant is a mixture of the alkyl glucoside and the nonylphenol polyoxyethylene ether; more preferably, the weight ratio of the alkyl glucoside to the nonylphenol polyoxyethylene ether is (0.5-1.5):1; Preferably, the surfactant is a mixture of the alkyl glucoside, the nonylphenol polyoxyethylene ether and the sodium butyl naphthalene sulfonate; more preferably, the weight ratio of the alkyl glucoside, the nonylphenol polyoxyethylene ether and the sodium butyl naphthalene sulfonate is 2:(1-1.5):(1-1.5).

5. The crystalline silicon texturing agent according to any one of claims 1 to 4, characterized in that: The pH value of the acid is 2 to 6; preferably 4 to 6; Preferably, the acid is selected from at least one of formic acid, acetic acid, citric acid and phosphoric acid; Preferably, the acid is a mixed acid of formic acid and acetic acid; more preferably, the weight ratio of the formic acid to the acetic acid is (0.5-1.5):1; Preferably, the acid is citric acid.

6. The crystalline silicon texturing agent according to any one of claims 1 to 5, characterized in that: The dispersant is selected from at least one of an ionic dispersant, a nonionic dispersant and an oily dispersant; Preferably, the ionic dispersant is a naphthalenesulfonic acid formaldehyde polymer sodium salt and / or a polycarboxylic acid sodium salt type dispersant; Preferably, the brand of the nonionic dispersant is Evonik dispersant 760W; Preferably, the brand of the polycarboxylate sodium salt dispersant is Nopco dispersant 5040; Preferably, the brand of the oily dispersant is AKN-2350; Preferably, the dispersant is a mixture of the AKN-2350 and the Evonik dispersant 760W; more preferably, the weight ratio of the AKN-2350 to the Evonik dispersant 760W is (0.5-1.5):1; Preferably, the dispersant is a mixture of the sodium salt of naphthalenesulfonic acid formaldehyde polymer and the Evonik dispersant 760W; more preferably, the weight ratio of the sodium salt of naphthalenesulfonic acid formaldehyde polymer to the Evonik dispersant 760W is 1:(0.5-1); Preferably, the dispersant is a mixture of the sodium salt of naphthalenesulfonic acid formaldehyde polymer and the Nopco dispersant 5040; more preferably, the weight ratio of the sodium salt of naphthalenesulfonic acid formaldehyde polymer to the Nopco dispersant 5040 is (0.5-1):0.5; Preferably, the dispersant is the naphthalenesulfonic acid formaldehyde polymer sodium salt.

7. The crystalline silicon texturing agent according to any one of claims 1 to 6, characterized in that: The bactericide is selected from hydroquinone and / or isothiazolinone; Preferably, the catechol is catechol; Preferably, the isothiazolinone is 5-chloro-2-methyl-4-isothiazolin-3-one and / or 2-methyl-4-isothiazolin-3-one; Preferably, the fungicide is a mixture of the catechol and the 5-chloro-2-methyl-4-isothiazolin-3-one; more preferably, the weight ratio of the catechol to the isothiazolinone is (0.5-1.5):1; Preferably, the bactericide is catechol; And / or, the water is deionized water.

8. A method for texturing crystalline silicon, characterized in that: The method comprises the following steps: Step S1: heating the texturing agent to 70-90° C.; wherein the texturing agent is the crystalline silicon texturing agent according to any one of claims 1 to 7; Step S2: placing the crystalline silicon to be textured into the heated texturing agent for reaction for 300 to 500 seconds to obtain the textured crystalline silicon.

9. A texturing method for monocrystalline silicon, characterized in that: The textured single crystal silicon is prepared by the textured method according to claim 8; Preferably, the average reflectivity of the textured single crystal silicon to sunlight is 9.5% to 12.6%; Preferably, the diameter of the pyramids in the textured surface of the single crystal silicon is 1.56-2.68 μm; Preferably, the number of pyramids on the surface of the texturing single crystal silicon is 420 to 520 per mm. 2 .

10. A solar cell, characterized in that: The solar cell comprises a silicon wafer; the silicon wafer is the textured single crystal silicon as described in claim 9.

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