Texturing agent composition of silicon wafer for monocrystalline silicon heterojunction solar cell, texturing liquid and solar cell

Abstract

The invention relates to a texturing agent composition of a silicon wafer for a monocrystalline silicon heterojunction solar cell. The texturing agent composition comprises the following components based on the total weight of the texturing agent composition: 0.01-10 wt% of an anionic surfactant; 0.001 to 15 wt% of a nonionic surfactant; 0.001 to 5 wt% of a nucleating agent; 0.0001 to 10 wt% of a dispersant; and water. The texturing agent composition disclosed by the invention comprises an anionic surfactant, a nonionic surfactant, a nucleating agent (an amino polysaccharide polymer) and a dispersing agent (an aromatic ring formaldehyde condensate), and the texturing agent composition is prepared into a texturing solution for silicon wafer texturing. Under the compounding condition of the components, on one hand, a novel flower-bud-shaped multilayer pyramid suede microstructure can be formed on the surface of a silicon wafer, and the reflectivity of the surface of the silicon wafer is reduced; and on the other hand, the textured silicon wafer is highly matched with the HJT battery, so that the photoelectric conversion efficiency of the HJT battery can be remarkably improved. Therefore, the texturing technology can be effectively applied to large-scale production of solar cells.

Description

Technical Field

[0001] The present disclosure relates to a texturing agent composition and a texturing solution for use in single crystal silicon wafers, particularly to a texturing agent composition and a texturing solution for heterojunction solar cells, including but not limited to, and belongs to the field of solar cell manufacturing. Background Art

[0002] As a clean and renewable energy source, solar energy is gradually becoming an important part of the global energy consumption. In the process of solar energy conversion and utilization, solar panels play a core role. Among them, single crystal silicon solar cells are favored for their high conversion efficiency and stable performance. Single crystal silicon solar cells are made from high-purity single crystal silicon rods through a series of complex technological processes. In these processes, texturing is a key step in the production of single crystal silicon solar cells.

[0003] In the existing single crystal silicon solar cell technology, heterojunction solar cells (Heterojunction with Intrinsic Thin-layer, HJT) have more significant advantages and potential. HJT solar cells are a new type of solar cell technology that combines the advantages of crystalline silicon cells and thin film cells. This technology forms a unique heterojunction structure by depositing a ultra-thin amorphous silicon film on a high-quality crystalline silicon substrate, specifically manifested as: higher potential for improving photoelectric conversion efficiency, greater cost reduction space, higher bifaciality, lower light-induced degradation, significantly reduced thermal loss, and simplified preparation process, etc.

[0004] Texturing is to form tiny pyramid-shaped structures on the surface of the silicon wafer through chemical etching, and this structure is called the textured surface. Specifically, the texturing process usually uses a low-concentration alkaline solution (such as sodium hydroxide) to etch the silicon wafer. Due to the crystal structure characteristics of single crystal silicon, the etching rates in different crystal orientations are different, thus forming a uniformly distributed pyramid-shaped textured surface on the silicon wafer surface. This textured surface structure can effectively reduce the reflection of sunlight on the silicon wafer surface and increase the light absorption efficiency. At the same time, the microscopic textured surface structure has an important impact on the photoelectric conversion efficiency of solar cells. In the process of preparing Topcon solar cells, it is necessary to ensure that the textured silicon wafer presents a fine and uniform morphology to reduce the reflectivity and thus achieve efficient photoelectric conversion. For the preparation of HJT solar cells, the uniformity and size of the pyramid-shaped textured surface structure become the key. Too small pyramids will hinder the uniform deposition of the amorphous silicon film. On the contrary, larger and uniform pyramid shapes can effectively increase the open circuit voltage of HJT solar cells, thus significantly enhancing their photoelectric conversion efficiency. Therefore, it is particularly important to develop a texturing agent composition and a texturing solution suitable for HJT solar cells. Summary of the Invention

[0005] In a first aspect, the present disclosure relates to an etching agent composition for a silicon wafer used in a monocrystalline silicon heterojunction solar cell, comprising the following components based on the total weight of the etching agent composition:

[0006] An anionic surfactant: 0.01 to 10 wt%;

[0007] A non-ionic surfactant: 0.001 to 15 wt%;

[0008] A nucleating agent: 0.001 to 5 wt%;

[0009] A dispersant: 0.0001 to 10 wt%;

[0010] Water; wherein the sum of the weight percentages of the components of the etching agent composition is 100 wt%;

[0011] The nucleating agent is an aminopolysaccharide polymer;

[0012] The dispersant is an aromatic ring type formaldehyde condensate.

[0013] In one embodiment, the aminopolysaccharide polymer is selected from one or more of chondroitin sulfate, keratan sulfate, hyaluronic acid, chitosan and its derivatives; the chitosan derivatives can be selected from one or more of carboxymethyl chitosan, N,N-dicarboxymethyl chitosan, hydroxypropyl chitosan, chitosan quaternary ammonium salt and carboxyethyl chitosan;

[0014] Preferably, the aminopolysaccharide polymer is selected from one or more of chondroitin sulfate, keratan sulfate and hyaluronic acid.

[0015] In one embodiment, the dispersant is an aromatic sulfonic acid compound formaldehyde condensate or an aromatic sulfonate compound formaldehyde condensate, preferably selected from one or more of benzylnaphthalenesulfonic acid formaldehyde condensate, naphthalenesulfonic acid formaldehyde condensate, and sodium methylnaphthalenesulfonate formaldehyde condensate.

[0016] In one embodiment, the anionic surfactant is selected from one or more of fatty alcohol polyoxyethylene ether sulfates, fatty alcohol sulfates, alkylbenzene sulfonates, hydroxybenzene sulfonates, and oleates;

[0017] Preferably, the anionic surfactant comprises a first anionic surfactant and an optional second anionic surfactant, wherein the first anionic surfactant is selected from fatty alcohol polyoxyethylene ether sulfates, and the optional second anionic surfactant is selected from the combination of hydroxybenzene sulfonates; preferably, the anionic surfactant comprises a combination of fatty alcohol polyoxyethylene ether sulfate and hydroxybenzene sulfonate, wherein the weight ratio of fatty alcohol polyoxyethylene ether sulfate to hydroxybenzene sulfonate is (1:4) to (4:1);

[0018] Preferably, the fatty alcohol polyoxyethylene ether sulfate has the molecular formula R-O-(CH2CH2O) n -SO3M, where R is a C12-C14 normal alkyl group, n is an integer between 13 and 20; M is an alkali metal such as Na or K; the fatty alcohol polyoxyethylene ether sulfate is, for example, sodium fatty alcohol polyoxyethylene ether sulfate.

[0019] In one embodiment, the nonionic surfactant is selected from one or more of alkylphenol polyoxyethylene ether (APE), fatty alcohol polyoxyethylene ether (AEO), fatty acid methyl ester ethoxylate (FMEE), and polyethylene glycol (PEG);

[0020] Preferably, the nonionic surfactant includes a first nonionic surfactant and an optional second nonionic surfactant, wherein the first nonionic surfactant is one or more fatty alcohol polyoxyethylene ethers (AEO) such as one or two of AEO-9 and AEO-15, and the optional second nonionic surfactant is selected from one or more of alkylphenol polyoxyethylene ether (APE), fatty acid methyl ester ethoxylate (FMEE), and polyethylene glycol (PEG), especially polyethylene glycol (PEG).

[0021] In one embodiment, the content of the anionic surfactant is 0.01-4 wt%, based on the total weight of the texturing agent composition; and / or

[0022] the content of the nonionic surfactant is 0.01-15 wt%, preferably 0.01-5 wt%, based on the total weight of the texturing agent composition; and / or

[0023] the content of the nucleating agent is 0.001-1 wt%, based on the total weight of the texturing agent composition; and / or

[0024] the content of the dispersant is 0.0005-5 wt%, based on the total weight of the texturing agent composition.

[0025] In one embodiment, the texturing agent composition further comprises a water-soluble polysaccharide, and the water-soluble polysaccharide is selected from one or more of carrageenan, locust bean gum, konjac gum, sodium carboxymethyl cellulose, and galactomannan;

[0026] Preferably, the content of the water-soluble polysaccharide is 0.001-8 wt%, based on the total weight of the texturing agent composition.

[0027] In a second aspect, the present disclosure also relates to a texturing solution, which comprises an alkali, the texturing agent composition of the first aspect of the present disclosure, an alkali, and water;

[0028] Preferably, the base is an inorganic base and / or an organic base; preferably, the inorganic base is KOH and / or NaOH, and the organic base is tetramethylguanidine and / or tetraethylammonium hydroxide;

[0029] Preferably, the amount of the texturing agent composition is 0.05 to 1.5 wt%, based on the total weight of the texturing solution; and / or, the amount of the base is 0.5 to 5.5 wt%, based on the total weight of the texturing solution.

[0030] In a third aspect, the present disclosure also relates to a silicon wafer, which is obtained by immersing a cleaned silicon wafer in the texturing solution of the second aspect of the present disclosure for texturing.

[0031] In a fourth aspect, the present disclosure also relates to a solar cell, including the silicon wafer of the third aspect of the present disclosure.

[0032] The texturing agent composition of the present disclosure includes an anionic surfactant, a nonionic surfactant, a nucleating agent (aminopolysaccharide polymer), and a dispersant (aromatic ring formaldehyde condensate). When it is made into a texturing solution for texturing silicon wafers, under the compounding conditions of these components, on the one hand, a new "flower bud-shaped" multi-layer pyramid texture microstructure can be formed on the surface of the silicon wafer, reducing the reflectivity of the silicon wafer surface; on the other hand, the textured silicon wafer is highly compatible with the HJT battery, and can significantly improve the photoelectric conversion efficiency of the HJT battery. Therefore, this texturing technology can be effectively applied to large-scale solar cell production. Description of the Drawings

[0033] Figure 1 Showing the SEM image of the textured surface of the silicon wafer obtained in Example 1;

[0034] Figure 2 Showing the SEM image of the textured surface of the silicon wafer obtained in Example 2;

[0035] Figure 3 Showing the SEM image of the textured surface of the silicon wafer obtained in Comparative Example 1;

[0036] Figure 4 Showing the SEM image of the textured surface of the silicon wafer obtained in Comparative Example 2. Detailed Description of the Embodiments

[0037] The present disclosure will be further described in detail below with reference to the drawings and embodiments. Through these descriptions, the features and advantages of the present disclosure will become more clearly defined.

[0038] The special term "exemplary" here means "serving as an example, an embodiment, or illustrative". Any embodiment described as "exemplary" here does not have to be construed as superior to or better than other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings do not have to be drawn to scale unless otherwise specified.

[0039] In addition, the technical features involved in different embodiments of the present disclosure described below can be combined with each other as long as they do not conflict with each other.

[0040] The present disclosure provides an etching agent composition for a silicon wafer used in a monocrystalline silicon heterojunction solar cell, comprising the following components based on the total weight of the etching agent composition:

[0041] An anionic surfactant: 0.01 - 10 wt%;

[0042] A nonionic surfactant: 0.001 - 15 wt%;

[0043] A nucleating agent: 0.001 - 5 wt%;

[0044] A dispersant: 0.0001 - 10 wt%;

[0045] Water; wherein, the sum of the weight percentages of the components of the etching agent composition is 100 wt%;

[0046] The nucleating agent is an amino polysaccharide polymer;

[0047] The dispersant is an aromatic ring type formaldehyde condensate.

[0048] The etching agent composition of the present disclosure contains an anionic surfactant, a nonionic surfactant, a nucleating agent (amino polysaccharide polymer) and a dispersant (aromatic ring type formaldehyde condensate). When it is made into an etching solution for silicon wafer etching, under the compounding conditions of these components, on the one hand, a new "flower bud-shaped" multi-layer pyramid textured microstructure can be formed on the surface of the silicon wafer. By increasing the reflection surface, when light irradiates the surface of the silicon wafer, it can experience more processes such as secondary reflection, tertiary reflection and multiple reflections, thereby effectively improving the light absorption of the silicon wafer after etching and reducing the reflectivity of the silicon wafer surface. On the other hand, the silicon wafer after etching is adapted to the HJT battery, and can significantly improve the photoelectric conversion efficiency of the HJT battery. As shown in the present disclosure Figure 1 and Figure 2 shown, in the silicon wafer with the "flower bud-shaped" multi-layer pyramid textured microstructure, the pyramid structures on the silicon wafer are more densely distributed, and multiple auxiliary pyramid structures are densely distributed around the main pyramid structure; compared with Figure 3 and Figure 4 the shown silicon wafers, the uniformity of the tip heights of each main pyramid structure and the uniformity of the tip heights of the auxiliary pyramid structures are better, and there are more reflection surfaces.

[0049] The texturing agent composition of the present disclosure comprises an anionic surfactant and a non-ionic surfactant. During the texturing process, the combined action of the anionic surfactant and the non-ionic surfactant is to inhibit the growth of Si-O-Si bonds after the Si-O-H reaction nucleates. By utilizing their specific hydrophobicity and hydrophilicity, the silicon etching rate can be controlled, such that after the textured silicon wafer is assembled into an HJT cell, the photoelectric conversion efficiency can be significantly improved.

[0050] In one embodiment, the anionic surfactant can be selected from one or more of fatty alcohol polyoxyethylene ether sulfates, fatty alcohol sulfates, alkylbenzene sulfonates, hydroxybenzene sulfonates, oleates. In one embodiment, the anionic surfactant can include fatty alcohol polyoxyethylene ether sulfate. For example, the fatty alcohol polyoxyethylene ether sulfate can have the molecular formula R-O-(CH2CH2O) n -SO3M, where R is a C12 - C14 normal alkyl group, n is an integer between 13 - 20; M is an alkali metal, such as Na or K. For example, the fatty alcohol polyoxyethylene ether sulfate can be sodium fatty alcohol polyoxyethylene ether sulfate.

[0051] In one embodiment, the anionic surfactant includes a first anionic surfactant and an optional second anionic surfactant, where the first anionic surfactant is selected from fatty alcohol polyoxyethylene ether sulfate, and the optional second anionic surfactant is selected from the combination of hydroxybenzene sulfonate; preferably, the anionic surfactant includes the combination of fatty alcohol polyoxyethylene ether sulfate and hydroxybenzene sulfonate, where the weight ratio of fatty alcohol polyoxyethylene ether sulfate to hydroxybenzene sulfonate is (1:4) - (4:1). In one embodiment, the fatty alcohol polyoxyethylene ether sulfate can be sodium fatty alcohol polyoxyethylene ether sulfate, and the hydroxybenzene sulfonate can be sodium hydroxybenzene sulfonate.

[0052] In one embodiment, the content of the anionic surfactant is 0.01 - 10 wt%, preferably 0.01 - 4 wt%, based on the total weight of the texturing agent composition.

[0053] In one embodiment, the non-ionic surfactant may be selected from one or more of alkylphenol polyoxyethylene ethers (APE), fatty alcohol polyoxyethylene ethers (AEO), fatty acid methyl ester ethoxylates (FMEE), and polyethylene glycols (PEG). In one embodiment, the non-ionic surfactant may include a first non-ionic surfactant and an optional second non-ionic surfactant, wherein the first non-ionic surfactant is one or two of one or more fatty alcohol polyoxyethylene ethers (AEO) such as AEO-9 and AEO-15, and the optional second non-ionic surfactant may be selected from one or more of alkylphenol polyoxyethylene ethers (APE), fatty acid methyl ester ethoxylates (FMEE), and polyethylene glycols (PEG), particularly polyethylene glycol (PEG).

[0054] In one embodiment, the content of the non-ionic surfactant is 0.001 to 15 wt%, particularly 0.01 to 15 wt%, preferably 0.01 to 5 wt%, based on the total weight of the texturing agent composition.

[0055] The texturing agent composition of the present disclosure contains an aminopolysaccharide polymer as a nucleating agent. The aminopolysaccharide polymer refers to a class of polysaccharide molecules in which the monosaccharide units are modified by amino groups (-NH). The role of this nucleating agent is to promote the nucleation of the Si-O-H reaction, thereby forming a "bud-shaped" multi-layer pyramid texture structure on the surface of the silicon wafer.

[0056] In one embodiment, the aminopolysaccharide polymer may be selected from one or more of chondroitin sulfate, keratan sulfate, hyaluronic acid, chitosan and its derivatives; the chitosan derivatives may be selected from one or more of carboxymethyl chitosan, N,N-dicarboxymethyl chitosan, hydroxypropyl chitosan, chitosan quaternary ammonium salt, and carboxyethyl chitosan; preferably, the aminopolysaccharide polymer is selected from one or more of chondroitin sulfate, keratan sulfate, and hyaluronic acid.

[0057] In one embodiment, the nucleating agent includes hyaluronic acid and an optional second aminopolysaccharide polymer, and the optional second aminopolysaccharide polymer is selected from one or more of chondroitin sulfate, keratan sulfate, chitosan and chitosan derivatives, such as chitosan derivatives.

[0058] In one embodiment, the content of the nucleating agent is 0.001 to 5 wt%, particularly 0.001 to 1 wt%, based on the total weight of the texturing agent composition.

[0059] The texturing agent composition of the present disclosure contains an aromatic ring formaldehyde condensate as a dispersant. The aromatic ring formaldehyde condensate refers to a substance formed by the condensation reaction of an aromatic aldehyde (such as benzaldehyde) with other compounds such as alcohol compounds like methanol, and can also be formed by the condensation reaction of an aromatic compound with active hydrogen on the aromatic ring (such as naphthalene sulfonic acid and its salts, and substituted naphthalene sulfonic acid and its salts) with formaldehyde. The aromatic ring formaldehyde condensate can contain multiple aromatic rings or heteroaromatic rings. In one embodiment, the dispersant can be an aromatic sulfonic acid compound formaldehyde condensate or an aromatic sulfonate compound formaldehyde condensate. The aromatic sulfonic acid compounds and their salts can be naphthalene sulfonic acid, benzyl naphthalene sulfonic acid, methyl naphthalene sulfonic acid, and their salts, such as sodium salts, potassium salts, etc. These aromatic sulfonic acid compounds and their salts have active hydrogen on the aromatic ring and can undergo a condensation reaction with formaldehyde in the presence of an acid or a base to obtain the corresponding condensate. In one embodiment, the aromatic ring formaldehyde condensate is selected from one or more of benzyl naphthalene sulfonic acid formaldehyde condensate, naphthalene sulfonic acid formaldehyde condensate, sodium methyl naphthalene sulfonate formaldehyde condensate, etc. These substances are commercially available. For example, naphthalene sulfonic acid formaldehyde condensate can be purchased from Shanghai Xiaoyan Technology Co., Ltd., benzyl naphthalene sulfonic acid formaldehyde condensate can be purchased from Shenzhen Shengyan Technology Co., Ltd., and sodium methyl naphthalene sulfonate formaldehyde condensate can be purchased from Shandong Wenhe New Materials Co., Ltd. (trade name dispersant MF). 。 The role of the dispersant is to prevent the precipitation and aggregation of the components of the texturing agent composition, such as the nucleating agent and the following water-soluble polymers, etc., can enhance the dispersibility of the texturing agent composition on the surface of the silicon wafer, and optimize the etching effect.

[0060] In one embodiment, the content of the dispersant is 0.0001 - 10 wt%, especially 0.0005 - 5 wt%, based on the total weight of the texturing agent composition.

[0061] In one embodiment, the texturing agent composition may further contain a water-soluble polysaccharide, and the water-soluble polysaccharide can be selected from one or more of carrageenan, locust bean gum, konjac gum, sodium carboxymethyl cellulose, galactomannan. The water-soluble polysaccharide can control the surface texture structure of the silicon wafer, and further improve the photoelectric conversion efficiency of the solar cell formed by the silicon wafer textured with the texturing liquid containing the texturing agent composition.

[0062] Carrageenan is a natural high-molecular hydrophilic polysaccharide extracted from red algae, which is composed of sulfated or non-sulfated galactose and 3,6-anhydrogalactose alternately linked by α-1,3 glycosidic bonds and β-1,4 bonds. Locust bean gum is a natural plant gum processed from the seeds of locust trees, which is a polysaccharide compound with galactose and mannose residues as structural units. Konjac gum is a water-soluble high-molecular polysaccharide extracted from konjac tubers, and its basic unit is composed of glucose residues and mannose residues. The glucose residues and mannose residues are linked by β-1,4-glycosidic bonds, and at the same time, some mannose residues will be acetylated. Sodium carboxymethyl cellulose is a water-soluble cellulose derivative obtained by chemically modifying natural cellulose. Its basic skeleton is a linear polysaccharide structure formed by D-glucose units linked by β-1,4-glycosidic bonds. The hydroxyl groups (-OH) on the cellulose main chain are partially replaced by carboxymethyl (-CH2COONa) to form sodium carboxymethyl cellulose. Galactomannan is a polysaccharide composed of mannose and galactose. Preferably, the water-soluble polysaccharide is selected from one or more of carrageenan, locust bean gum, konjac gum, sodium carboxymethyl cellulose, and galactomannan.

[0063] In one embodiment, the content of the water-soluble polysaccharide is 0.001 to 8 wt%, based on the total weight of the texturing agent composition.

[0064] In one embodiment, the texturing agent composition of the present disclosure may comprise the following components:

[0065] An anionic surfactant;

[0066] A nonionic surfactant;

[0067] A nucleating agent;

[0068] A dispersant;

[0069] A water-soluble polysaccharide; and

[0070] Water,

[0071] wherein the anionic surfactant includes a first anionic surfactant and an optional second anionic surfactant, wherein the first anionic surfactant is selected from fatty alcohol polyoxyethylene ether sulfates, and the optional second anionic surfactant is selected from combinations of p-hydroxybenzenesulfonates; preferably, the anionic surfactant includes a combination of fatty alcohol polyoxyethylene ether sulfates and p-hydroxybenzenesulfonates, wherein the weight ratio of fatty alcohol polyoxyethylene ether sulfates to p-hydroxybenzenesulfonates is (1:4) to (4:1);

[0072] The non-ionic surfactant includes a first non-ionic surfactant and an optional second non-ionic surfactant, wherein the first non-ionic surfactant is one or more fatty alcohol polyoxyethylene ethers (AEO), and the optional second non-ionic surfactant is selected from polyethylene glycol (PEG);

[0073] The nucleating agent includes hyaluronic acid and an optional second aminopolysaccharide polymer, and the optional second aminopolysaccharide polymer is selected from one or more of chondroitin sulfate, keratan sulfate, chitosan, and chitosan derivatives;

[0074] The dispersant is selected from one or more of benzylnaphthalenesulfonic acid formaldehyde condensate, naphthalenesulfonic acid formaldehyde condensate, sodium methylnaphthalenesulfonate formaldehyde condensate, etc.;

[0075] The water-soluble polysaccharide is selected from one or more of carrageenan, locust bean gum, konjac gum, sodium carboxymethyl cellulose, and galactomannan;

[0076] Wherein, based on the total weight of the texturing agent composition, the total amount of the anionic surfactant is 0.01 - 4 wt%, the total amount of the non-ionic surfactant is 0.01 - 15 wt%, the total amount of the nucleating agent is 0.001 - 1 wt%, the total amount of the dispersant is 0.0005 - 5 wt%, the total amount of the water-soluble polysaccharide is 0.001 - 8 wt%, and the sum of the weight percentages of the components of the texturing agent composition is 100 wt%.

[0077] The present disclosure provides a texturing solution comprising an alkali, the above-mentioned texturing agent composition of the present disclosure, and water.

[0078] In one embodiment, the alkali is an inorganic alkali and / or an organic alkali; preferably, the inorganic alkali is KOH and / or NaOH, and the organic alkali is tetramethylguanidine and / or tetraethylammonium hydroxide.

[0079] In one embodiment, the amount of the texturing agent composition is 0.05 - 1.5 wt%, based on the total weight of the texturing solution; the amount of the alkali is 0.5 - 5.5 wt%, based on the total weight of the texturing solution.

[0080] The texturing solution can be prepared as follows: in a texturing tank, dissolve a certain mass of inorganic alkali / organic alkali in ultrapure water to prepare an alkali solution with a mass concentration of 0.5 - 5.5 wt%; then add the texturing agent composition of the present disclosure to the prepared alkali solution, and the content of the texturing agent composition is 0.05 - 1.5 wt% (based on the total weight of the texturing solution), and stir evenly to obtain the texturing solution.

[0081] The present disclosure also relates to a texturing method and the textured silicon wafer obtained thereby. Specifically, the texturing method includes putting the silicon wafer to be textured after cleaning (such as N-type monocrystalline silicon or P-type monocrystalline silicon) into the above-mentioned texturing solution of the present disclosure, and performing texturing operation at 75 - 82 °C, so as to prepare a silicon wafer with a "flower bud-shaped" multi-layer pyramid texture structure, and the required texturing time can be 600 s. The above-mentioned silicon wafer can be N-type monocrystalline silicon, P-type monocrystalline silicon, etc. After the textured silicon wafer is assembled into an HJT battery, the photoelectric conversion efficiency can be significantly improved.

[0082] Therefore, the present disclosure also relates to a solar cell (especially a monocrystalline silicon HJT battery), which includes the above-mentioned textured silicon wafer of the present disclosure.

[0083] Some embodiments are listed below for illustration and should not be considered as a limitation to the present disclosure.

[0084] Examples and Comparative Examples

[0085] The texturing solution for monocrystalline silicon wafers is prepared as follows:

[0086] 1) Prepare the texturing agent composition: Weigh the corresponding substances according to Tables 1-1 to 1-3, stir each component evenly, and then filter through a 500-mesh nylon filter cloth to remove fine particles to obtain the silicon wafer texturing agent composition.

[0087] 2) Prepare the texturing solution: In the texturing tank, dissolve a certain mass of potassium hydroxide in ultrapure water to prepare an alkali solution with a mass concentration of 4 wt%, and then add the texturing agent composition prepared in 1) to the prepared alkali solution. The content of the texturing additive composition is 0.45 wt% (based on the total weight of the texturing solution), and after bubbling and stirring evenly, the texturing solution is obtained.

[0088] Texturing process:

[0089] The cleaned silicon wafer (N-type silicon wafer, size 182.2 μm × 183.75 μm, thickness 130 μm) is added to the texturing solution, and at 80 °C, the etching time is 600 s. The textured silicon wafer is washed with deionized water, and the deionized water on the surface of the washed silicon wafer is blown dry with high-purity nitrogen.

[0090] After that, the weight loss rate, average reflectivity, and five-point reflectivity deviation of the silicon wafer are measured:

[0091] Weight loss rate = (weight of the original silicon wafer - weight of the textured silicon wafer) / weight of the original silicon wafer

[0092] The reflectivity and the range of the five-point reflectivity deviation were obtained by a D8 reflectometer. The SEM images were obtained by a field emission scanning electron microscope (Zeiss Gemini SEM 500). The weight loss rate was calculated by weighing the silicon wafers before and after texturing using an electronic balance. A large five-point reflectivity deviation indicates poor appearance uniformity of the textured silicon wafers. Combining with the SEM photos, the uniformity of the pyramid distribution can be confirmed.

[0093] The raw materials used in the examples and comparative examples can be obtained through commercial channels, as follows.

[0094] Nucleating agent

[0095] A1: Chondroitin sulfate, purchased from Shanghai Yuanye Bio-Technology Co., Ltd., analytical pure standard product;

[0096] A2: Hyaluronic acid, purchased from Shanghai Macklin Biochemical Co., Ltd., molecular weight 100,000 - 200,000;

[0097] A3: Keratan sulfate, purchased from Jinan Glecon Biotechnology Co., Ltd., purity > 90%;

[0098] A4: Carboxymethyl chitosan, purchased from Shanghai Yuanye Bio-Technology Co., Ltd., carboxylation degree ≥ 80%;

[0099] NA: Sodium carboxymethyl cellulose, purchased from Shanghai Macklin Biochemical Co., Ltd., viscosity 600 - 3000 mPa·s.

[0100] Dispersant

[0101] B1: Sodium methylnaphthalenesulfonate formaldehyde condensate, purchased from Shandong Wenhe New Materials Co., Ltd.;

[0102] B2: Benzylnaphthalenesulfonic acid formaldehyde condensate, purchased from Shenzhen Shengyan Technology Co., Ltd.;

[0103] B3: Sodium naphthalenesulfonate formaldehyde condensate, purchased from Shanghai Xiaoyan Technology Co., Ltd.;

[0104] NB: Sodium polyacrylate, purchased from Hubei Xinhongli Chemical Co., Ltd.

[0105] Surfactant 1 (anionic surfactant)

[0106] C1: Sodium lauryl polyoxyethylene sulfate, purchased from Shandong Tongfengqi Chemical Co., Ltd.;

[0107] C2: Sodium 4-hydroxybenzenesulfonate, purchased from Shandong Haizhou Bio-Engineering Co., Ltd.

[0108] Surfactant 2 (non-ionic surfactant)

[0109] D1: Alcohol polyoxyethylene ether AEO-9, purchased from Nantong Deyi Chemical Co., Ltd.;

[0110] D2: Alcohol polyoxyethylene ether AEO-15, purchased from Shanghai Kelaman Reagent Co., Ltd.;

[0111] D3: Polyethylene glycol, purchased from Shanghai Macklin Biochemical Co., Ltd., PEG-200 - 1000;

[0112] D4: Alkylolamide, purchased from Shanghai Kelaman Reagent Co., Ltd.

[0113] Water-soluble polysaccharide

[0114] E1: Carrageenan, purchased from Hubei Jusheng Technology Co., Ltd.;

[0115] E2: Locust bean gum, purchased from Shandong Yaheng Biotechnology Co., Ltd.;

[0116] E3: Sodium carboxymethyl cellulose, purchased from Shanghai Macklin Biochemical Co., Ltd., viscosity 600 - 3000 mPa·s;

[0117] E4: Galactomannan, purchased from Shanghai Zhenzhun Biotechnology Co., Ltd.

[0118] Table 1-1

[0119]

[0120] Table 1-2

[0121]

[0122] Table 1-3

[0123]

[0124] The monocrystalline silicon wafers after texturing with the texturing solutions obtained using the texturing agent compositions of Examples 1 - 2 and Comparative Examples 1 - 2 were respectively subjected to SEM analysis, as Figures 1-4 shown. Figures 1-4 The SEM pictures of the monocrystalline silicon wafers after texturing with the texturing solutions obtained using the texturing agent compositions of Examples 1 - 2 and Comparative Examples 1 - 2 are respectively shown. It can be seen that the monocrystalline silicon wafers obtained using the texturing solutions containing the texturing agent composition of the present disclosure and the texturing solutions containing commercial texturing additives can be uniformly textured. The surface of the monocrystalline silicon wafers obtained using the texturing solution containing the texturing agent composition of the present disclosure has an obvious "flower bud-shaped" textured multi-layer pyramid structure; while the monocrystalline silicon wafers textured with the texturing solution obtained using the texturing agent composition of Comparative Example 2 did not achieve uniform texturing, and the micro-structure did not cover the silicon wafer.

[0125] The weight loss rates, average reflectivities, and five-point reflectivity deviations of Examples 1 to 4 and Comparative Examples 1 to 2 are shown in Table 2.

[0126] Table 2

[0127]

[0128]

[0129] As can be seen from Table 2, the reflectivities and weight loss performances of the single-crystalline silicon wafers obtained by using the texturing solution containing the texturing agent composition of the present disclosure and the texturing solution containing a commercial texturing additive are similar, while the reflectivity of the single-crystalline silicon wafer obtained by using the texturing solution prepared with the texturing agent composition of Comparative Example 2 is abnormally high.

[0130] Preparation and testing of HJT solar cell wafers:

[0131] After cleaning the textured single-crystalline silicon wafer, an intrinsic amorphous silicon thin film with a thickness of 5 - 10 nm and a boron-doped P-type amorphous silicon thin film with a thickness of 5 - 10 nm are sequentially deposited on its front surface by PECVD process, and an intrinsic amorphous silicon thin film with a thickness of 5 - 10 nm and a phosphorus-doped N-type amorphous silicon thin film with a thickness of 5 - 10 nm are deposited on its back surface to form a p-n heterojunction.

[0132] After completing the CVD process, a transparent conductive oxide (TCO) film with a thickness of 100 nm is deposited on both sides of the silicon wafer by PVD process. Finally, electrodes are prepared on both sides of the silicon wafer by using low-temperature silver paste printing and low-temperature soldering processes, and low-temperature curing is carried out to obtain the cell wafer.

[0133] The obtained cell wafers are tested for their photovoltaic conversion performance indicators: Uoc (open-circuit voltage), Isc (short-circuit current), FF (fill factor), Rs (series resistance), Rsh (shunt resistance), and Eta (photovoltaic conversion efficiency) by a solar simulation electrical efficiency tester. The test conditions are: light intensity 1000 W / m², temperature 25 °C, and spectrum AM1.5G.

[0134] The single-crystalline silicon wafer is textured with the texturing solution prepared with the texturing agent composition of Comparative Example 1, and the cell wafer (hereinafter referred to as the reference cell wafer) is prepared according to the above process flow, and its Uoc, Isc, FF, Rs, Rsh, and Eta are measured.

[0135] The texturing solutions prepared from the texturing agent compositions of Examples 1 to 19 and Comparative Examples 2 to 6 were used to texture monocrystalline silicon wafers, and the corresponding solar cells were prepared according to the above process. The Uoc, Isc, FF, Rs, Rsh, and Eta of these solar cells were also measured, and the differences ΔEta, ΔUoc, ΔIsc, ΔFF, ΔRs, and ΔRsh of these solar cells relative to the reference solar cell were recorded.

[0136] Table 3

[0137] Group ΔEta ΔUoc ΔIsc ΔFF ΔRs ΔRsh Comparative Example 1 0.0000 0 0 0 0 0 Example 1 0.0050 -0.0008 0.021 -0.02 -0.00007 264 Example 2 0.0200 0.001 -0.006 -0.15 0.00003 -306.4 Example 3 0.0100 0.0004 -0.014 -0.16 0.00003 124.5 Example 4 0.0100 0.0014 -0.008 -0.15 0.00007 74.2 Comparative Example 2 -0.4200 -0.0006 0.032 -1.52 0.001 1038 Example 5 0.0010 0.0002 -0.004 0.002 0.00002 -243 Example 6 0.0100 0 0.04 -0.21 0.00013 -256.8 Comparative Example 3 -0.2800 -0.0007 -0.029 -0.63 0.003 1158 Example 7 0.0300 0.0006 0.023 -0.18 0.00003 -763.8 Example 8 0.0300 0.002 0.001 -0.16 0.00001 137.8 Example 9 0.0100 0.0005 0.04 -0.51 0.00017 -200.6 Example 10 0.0100 0.0003 0.025 -0.17 0.00008 -357 Comparative Example 4 -0.0500 -0.0031 -0.0015 -0.21 0.00007 824.8 Comparative Example 5 -0.0400 0.003 0.008 -0.44 0.00009 -325 Comparative Example 6 -0.0400 -0.004 0.001 -0.3 -0.00003 -576.2 Example 11 0.0410 0.001 -0.017 0.1 0 -335 Example 12 0.0300 -0.0003 0.033 -0.29 0.00007 20.6 Example 13 0.0540 0.0012 -0.016 0.13 -0.00001 -348 Example 14 0.0400 0.0004 0.035 -0.36 0.00012 -66.2 Example 15 0.0300 0.0002 0.019 -0.13 0.00003 -247.2 Example 16 0.0340 0.001 -0.021 0.12 0.00001 -777 Example 17 0.0200 -0.0001 0.017 -0.12 0.00043 90.9 Example 18 0.0300 0.0006 0.0001 0.02 -0.00008 -371 Example 19 0.0300 0.0009 -0.002 -0.04 0.00004 -348.4

[0138] As can be seen from Table 3, the ΔEta values of Examples 1 to 19 are higher, indicating that the silicon wafers textured with the texturing solution containing the texturing agent composition of the present disclosure are more suitable for HJT solar cells and can significantly improve the photoelectric conversion efficiency of HJT solar cells.

[0139] The present disclosure has been described in conjunction with preferred embodiments, but these embodiments are merely exemplary and only serve an illustrative purpose. On this basis, various substitutions and improvements can be made to the present disclosure, and these all fall within the protection scope of the present disclosure.

Claims

1. A texturing agent composition for silicon wafers for monocrystalline silicon heterojunction solar cells, comprising the following components based on the total weight of the texturing agent composition: Anionic surfactant 0.01-10wt%; Nonionic surfactant 0.001-15wt%; Nucleating agent 0.001-5wt%; Dispersant 0.0001~10wt%; water; among them, The sum of the weight percentages of the components of the texturing agent composition is 100wt%; The nucleating agent is an amino polysaccharide polymer; The dispersant is an aromatic ring formaldehyde condensate.

2. The texturing agent composition according to claim 1, wherein The aminopolysaccharide polymer is selected from one or more of chondroitin sulfate, keratan sulfate, hyaluronic acid, chitosan and derivatives thereof; the chitosan derivative can be selected from one or more of carboxymethyl chitosan, N,N-dicarboxymethyl chitosan, hydroxypropyl chitosan, chitosan quaternary ammonium salt and carboxyethyl chitosan; Preferably, the aminopolysaccharide polymer is selected from one or more of chondroitin sulfate, keratan sulfate and hyaluronic acid.

3. The texturing agent composition according to claim 1, wherein The dispersant is an aromatic sulfonic acid compound formaldehyde condensate or an aromatic sulfonate compound formaldehyde condensate, preferably one or more selected from benzylnaphthalenesulfonic acid formaldehyde condensate, naphthalenesulfonic acid formaldehyde condensate, and sodium methylnaphthalenesulfonate formaldehyde condensate.

4. The texturing agent composition according to claim 1, wherein The anionic surfactant is selected from one or more of fatty alcohol polyoxyethylene ether sulfate, fatty alcohol sulfate, alkylbenzene sulfonate, hydroxybenzene sulfonate, and oleate; Preferably, the anionic surfactant comprises a first anionic surfactant and an optional second anionic surfactant, wherein the first anionic surfactant is selected from a combination of fatty alcohol polyoxyethylene ether sulfates and the optional second anionic surfactant is selected from a combination of p-hydroxybenzene sulfonates; preferably, the anionic surfactant comprises a combination of fatty alcohol polyoxyethylene ether sulfates and p-hydroxybenzene sulfonates, wherein the weight ratio of fatty alcohol polyoxyethylene ether sulfates to p-hydroxybenzene sulfonates is (1:4) to (4:1); Preferably, the fatty alcohol polyoxyethylene ether sulfate has the molecular formula RO-(CH2CH2O) n -SO3M, R is a C12-C14 n-alkyl group, n is an integer between 13 and 20; M is an alkali metal, such as Na or K; and the fatty alcohol polyoxyethylene ether sulfate is, for example, sodium fatty alcohol polyoxyethylene ether sulfate.

5. The texturing agent composition according to claim 1, wherein The nonionic surfactant is selected from one or more of alkylphenol polyoxyethylene ether (APE), fatty alcohol polyoxyethylene ether (AEO), fatty acid methyl ester ethoxylate (FMEE) and polyethylene glycol (PEG); Preferably, the nonionic surfactant comprises a first nonionic surfactant and an optional second nonionic surfactant, wherein the first nonionic surfactant is one or more fatty alcohol polyoxyethylene ethers (AEO), such as one or two of AEO-9 and AEO-15, and the optional second nonionic surfactant is selected from one or more of alkylphenol polyoxyethylene ethers (APE), fatty acid methyl ester ethoxylate (FMEE) and polyethylene glycol (PEG), in particular polyethylene glycol (PEG).

6. The texturing agent composition according to any one of claims 1 to 5, wherein The content of the anionic surfactant is 0.01 to 4 wt %, based on the total weight of the texturing agent composition; and / or The content of the nonionic surfactant is 0.01 to 15 wt %, preferably 0.01 to 5 wt %, based on the total weight of the texturing agent composition; and / or The content of the nucleating agent is 0.001 to 1 wt %, based on the total weight of the texturing agent composition; and / or The content of the dispersant is 0.0005-5 wt %, based on the total weight of the texturing agent composition.

7. The texturing agent composition according to any one of claims 1 to 6, wherein The texturing agent composition further comprises a water-soluble polysaccharide, wherein the water-soluble polysaccharide is selected from one or more of carrageenan, locust bean gum, konjac gum, sodium carboxymethyl cellulose, and galactomannan; Preferably, the content of the water-soluble polysaccharide is 0.001-8 wt %, based on the total weight of the texturing agent composition.

8. A texturing liquid comprising a base, the texturing agent composition according to any one of claims 1 to 7, a base and water; Preferably, the base is an inorganic base and / or an organic base; preferably, the inorganic base is KOH and / or NaOH, and the organic base is tetramethylguanidine and / or tetraethylammonium hydroxide; Preferably, the amount of the texturing agent composition is 0.05-1.5 wt %, based on the total weight of the texturing liquid; and / or the amount of the alkali is 0.5-5.5 wt %, based on the total weight of the texturing liquid.

9. A silicon wafer, which is obtained by immersing the cleaned silicon wafer in the texturing liquid of claim 8 for texturing.

10. A solar cell comprising the silicon wafer according to claim 9.

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