Texturing additive for improving efficiency of solar cell and preparation method and application thereof
By using specific copolymers and compounds in the velvet-making additives, the reaction rate between the alkali and the silicon wafer surface is regulated, and the pyramid structure unevenness and velvet crushing problems caused by the existing velvet-making additives are solved, and more efficient photovoltaic cell preparation is achieved and battery efficiency is improved.
Patent Information
- Application Number
- CN202510041089.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-10
- Publication Date
- 2025-05-06
AI Technical Summary
After the existing velvet-making additives, the suede pyramids have different sizes and high velvet crushing rate, resulting in an increase in surface defects of the silicon wafer, affecting the contact effect and battery efficiency of the subsequent process.
A copolymer containing a vinyl pyrrolidone unit structure is used as the main nucleation agent, and a compound containing a nitrobenzene structure is used as the auxiliary nucleation agent. By regulating the contact reaction rate between the alkali and the silicon wafer surface, the surface tension of the reaction interface is reduced, bubble separation is promoted, and a more uniform, regular and dense pyramid structure is formed.
It significantly improves the number of nucleation points on the surface of the silicon wafer and the uniformity of the pyramid structure, reduces the reflectivity, and enhances the process adaptability and battery conversion efficiency of the rear channel.
Smart Images
Figure CN119932712A_ABST
Abstract
Description
Technical Field
[0001] The present invention is applied to the field of photovoltaic cell production and manufacturing, and specifically relates to a texturing additive for improving the efficiency of solar cells, and a preparation method and application thereof. Background Art
[0002] The texturing treatment of silicon wafer surface is a major step in the production process of photovoltaic cells. The main purpose of the texturing process is to perform a texturing reaction on the surface of the silicon wafer, that is, to form a layer of uneven pyramid velvet structure on the surface of the silicon wafer. This structure can produce a significant light trapping effect while increasing the surface area of the silicon wafer, thereby reducing the reflectivity of the silicon wafer surface and allowing more sunlight to be absorbed by the silicon wafer. Between the velvet pyramid structures, the incident light can be reflected multiple times, thereby significantly increasing the interaction between light and the cell, and enhancing its collection of photogenerated carriers, thereby improving the conversion efficiency of the cell.
[0003] The texturing process mainly uses chemical corrosion (mainly alkaline or acidic solutions) to etch a pyramid structure on the surface of the silicon wafer. Considering that single-crystal silicon has a regular crystal structure, alkaline solutions such as sodium hydroxide (NaOH) or potassium hydroxide (KOH) are often used as etching solutions for texturing reactions. During the texturing reaction, since the Si (100) crystal plane has more dangling bonds than the Si (111) crystal plane, the OH - The corrosion rate of Si(100) crystal surface is relatively fast. - Anisotropic etching of different silicon crystal planes leads to the formation of a large number of pyramid structures on the surface of silicon wafers. Texturing additives can form a uniform and dense pyramid-shaped texture structure on the surface of silicon wafers by controlling the etching reaction rate of alkaline solution on different silicon crystal planes. In addition, texturing additives can significantly shorten the texturing time and reduce the alkali consumption during the reaction process. However, the existing texturing additives on the market have the problems of uneven sizes of the texture pyramids after texturing and high texture breakage rate. These problems will lead to an increase in defects on the surface of silicon wafers, thereby destroying the contact effect between the texture and the passivation layer in the subsequent process, and then affecting the uniformity of the coating, resulting in a loss of battery efficiency. Summary of the invention
[0004] Purpose of the invention: In order to solve the above problems, the present invention provides a texturing additive for improving the efficiency of solar cells, and its preparation method and application. This additive can more accurately control the contact reaction rate between the alkali and the surface of the silicon wafer, effectively reduce the surface tension of the reaction interface, promote the rapid separation of bubbles generated by the reaction, and form a more uniform, regular, and dense pyramid structure on the surface of the silicon wafer. The velvet surface of the silicon wafer obtained after the texturing reaction using the additive of the present invention is more uniform, has a lower reflectivity, and has better adaptability to subsequent processes and higher conversion efficiency.
[0005] Technical solution: In order to achieve the above technical objectives, the present invention adopts the following technical solution:
[0006] A texturing additive for improving the efficiency of solar cells, the texturing additive comprising the following components in percentage by mass:
[0007] 0.01%-0.1% of a main nucleating agent, 0.05%-0.2% of an auxiliary nucleating agent, 0.05%-0.5% of a dispersant, 0.5%-1% of a corrosion inhibitor, and the remainder is water; the main nucleating agent is a copolymer containing a vinyl pyrrolidone unit structure, and the auxiliary nucleating agent is a compound containing a nitrobenzene structure.
[0008] Preferably, the texturing additive comprises the following components in percentage by mass:
[0009] 0.02%-0.06% of the main nucleating agent, 0.05%-0.15% of the auxiliary nucleating agent, 0.1%-0.2% of the dispersant, 0.5%-0.8% of the corrosion inhibitor, and the rest is water.
[0010] As a specific embodiment, the structural formula of the primary nucleating agent is as follows:
[0011]
[0012] Wherein, R is selected from vinyl alcohol, styrene, vinyl imidazole, hexadecene, isopropyl acrylamide, methacrylamide, acrylamide, methyl methacrylate, acrylic acid, vinyl acetate, butyl acrylate, methacrylic acid or maleic anhydride structural unit. In the structural formula, n represents the number of vinyl pyrrolidone structural units contained in the copolymer, and the molecular weight of the copolymer ranges from 20000 to 1000000 g / mol.
[0013] As a specific embodiment, the structural formula of the auxiliary nucleating agent is as follows:
[0014]
[0015] Wherein, R1, R2, R3, R4, and R5 are independently selected from H, halogen, alkyl, alkoxy, amine, amide, aldehyde, hydrazine, sulfonic acid / sulfonate, phenol / phenolate, carboxyl, or ester.
[0016] As a further embodiment, R1, R2, R3, R4, and R5 are independently selected from H, halogen, C1-C10 alkyl, -NH2, -(CH2) m CONH2, -(CH2) pCHO, -NHNH2, -SO3R6, -OR7 or -COOR8, wherein m and p are natural numbers, and m=0-5, p=0-5, R6 is selected from H or a metal atom, and R7 and R8 are independently selected from H, a metal atom or a C1-C5 alkyl group.
[0017] As a preferred embodiment, R1, R2, R3, R4, and R5 are independently selected from H, halogen, C1-C3 alkyl, -NH2, -CONH2, -CHO, -NHNH2, -SO3R6, -OR7, and -COOR8; R6 is selected from H, Na or K, and R7 and R8 are independently selected from H, Na, K or C1-C2 alkyl; at least three of R1, R2, R3, R4, and R5 are selected from H.
[0018] As a specific embodiment, the dispersant is selected from one or a combination of sodium lignin sulfonate, alkyl polyglucoside, sodium polymethacrylate, sulfonated polystyrene, polyvinyl alcohol, sodium polyacrylate or polysaccharide compounds. The structural formula of the polysaccharide compound is (C6H 10 O5) n In this structural formula, C6H 10 O5 represents the monosaccharide unit after removing one water molecule, and n represents the number of monosaccharide units in the polysaccharide.
[0019] As a preferred embodiment, the polysaccharide compound is selected from maltose, carrageenan, starch, lactose, cellulose, chitin, xanthan gum, inulin, polymannose or polyxylose.
[0020] As a specific implementation, the corrosion inhibitor is selected from one or a combination of sodium chloride, sodium dihydrogen phosphate, sodium carbonate, sodium citrate, sodium acetate, and sodium silicate.
[0021] The present invention also provides a method for preparing the texturing additive for improving the efficiency of solar cells, comprising the following steps:
[0022] According to the mass percentage, the nucleating agent, the auxiliary nucleating agent, the dispersant and the corrosion inhibitor are added into water, and stirred and mixed evenly to obtain the product.
[0023] The invention also provides application of the texturing additive in silicon wafer texturing.
[0024] As a specific implementation, the texturing additive is used in the texturing reaction of silicon wafers to improve the efficiency of solar cells.
[0025] As a specific implementation scheme, the application includes:
[0026] (1) dissolving soda ash in water and mixing evenly to obtain an alkaline solution, and then adding the texturing additive to the prepared alkaline solution and mixing evenly to prepare a mixed texturing agent;
[0027] (2) Immerse the silicon wafer in the mixed texturing agent to carry out texturing reaction.
[0028] As a further implementation:
[0029] In step (1), the alkali is selected from NaOH or KOH; the mass concentration of the alkali solution is 0.5%-1%; the mass ratio of the texturing additive to the alkali solution is 0.3-0.8:100;
[0030] In step (2), the temperature of the texturing reaction is controlled between 75-85°C, and the reaction time is between 350s-450s.
[0031] Beneficial effects: Compared with the prior art, the present invention has the following advantages:
[0032] (1) During the texturing reaction of solar cell wafers, the use of the additive of the present invention can effectively regulate the contact reaction rate between the alkali and the silicon wafer surface, increase the surface coverage of the reaction, reduce the surface tension of the reaction interface, and allow the hydrogen bubbles generated by the reaction to quickly detach, thereby increasing the number of nucleation points on the silicon wafer surface, thereby forming a more uniform, regular, and dense pyramid structure.
[0033] (2) The textured surface of the silicon wafer obtained by using the additive of the present invention to carry out the texture making reaction is more uniform, has lower reflectivity, has better adaptability to the subsequent process and higher battery conversion efficiency.
[0034] (3) In the present invention, the auxiliary nucleating agent mainly functions to enhance the adsorption capacity of the nucleating agent on the surface of the silicon wafer, so that the nucleating agent molecules are densely and evenly spread on the surface of the silicon wafer, inducing the formation of nucleation points. Therefore, the synergistic effect of the two makes the nucleation process more uniform and efficient, and helps to form a denser and more uniform pyramid structure. BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Figure 1 A microscope image of the textured surface of a silicon wafer obtained after the texturing reaction in Example 1 is shown.
[0036] Figure 2 A microscope image of the textured surface of a silicon wafer obtained after the texturing reaction in Comparative Example 1 is shown. DETAILED DESCRIPTION
[0037] The present invention is further described by the following examples. These examples are purely illustrative and are only used to specifically describe the present invention and should not be construed as limiting the present invention. The invention is further described below in conjunction with the accompanying drawings and examples:
[0038] Example 1
[0039] Preparation of additives: The additives are prepared by uniformly mixing 0.06% by mass of vinyl pyrrolidone-styrene copolymer (molecular weight 21500 g / mol) as a main nucleating agent, 0.05% by mass of sodium p-nitrobenzene sulfonate as an auxiliary nucleating agent, 0.2% by mass of alkyl polyglucoside as a dispersant, 0.5% by mass of sodium chloride as a corrosion inhibitor, and the remainder by mass of deionized water.
[0040] Add 30L of deionized water to a 40L texturing reaction tank, heat the temperature to 82°C, add 150g of NaOH, stir until dissolved to obtain a 0.5% alkaline solution, and then add 100g of the additive prepared in the above steps to the alkaline solution. After stirring evenly, a mixed texturing agent is prepared, and the silicon wafer is immersed in the tank for a texturing reaction of 420s. After the reaction is completed, the silicon wafer is dried and characterized and analyzed.
[0041] Example 2
[0042] The additive and the mixed texturing agent are prepared according to the method of Example 1 for texturing reaction, except that the additive is prepared by uniformly mixing 0.02% by mass of vinyl pyrrolidone-vinyl alcohol copolymer (molecular weight 31000 g / mol) as a nucleating agent, 0.15% of sodium 3-nitrobenzoate as an auxiliary nucleating agent, 0.1% of maltose as a dispersant, 0.8% of sodium citrate as a corrosion inhibitor, and the remainder of deionized water.
[0043] Example 3
[0044] The additive and the mixed texturing agent are prepared according to the method of Example 1 for texturing reaction, except that the additive is prepared by uniformly mixing 0.03% by mass of vinyl pyrrolidone-vinyl acetate copolymer (molecular weight 39400 g / mol) as a nucleating agent, 0.06% of sodium 2-methoxy-5-nitrophenol as an auxiliary nucleating agent, 0.1% of sodium lignin sulfonate as a dispersant, 0.6% of sodium dihydrogen phosphate as a corrosion inhibitor, and the remainder of deionized water.
[0045] Example 4
[0046] The additive and the mixed texturing agent are prepared according to the method of Example 1 for texturing reaction, except that the additive is prepared by uniformly mixing 0.04% by mass of vinyl pyrrolidone-acrylamide copolymer (molecular weight 109200 g / mol) as a nucleating agent, 0.1% by mass of 2-nitroaniline as an auxiliary nucleating agent, 0.15% by mass of sodium polyacrylate as a dispersant, 0.7% by mass of sodium acetate as a corrosion inhibitor, and the remainder of deionized water.
[0047] Example 5
[0048] The additive and the mixed texturing agent are prepared according to the method of Example 1 for texturing reaction, except that the additive is composed of 0.02% by mass of vinyl pyrrolidone-vinyl imidazole copolymer (molecular weight 164000 g / mol) as a nucleating agent, 0.12% of sodium 3-nitrobenzoate as an auxiliary nucleating agent, 0.18% of chitin as a dispersant, 0.6% of sodium carbonate as a corrosion inhibitor, and the remainder of deionized water and then mixed evenly to form the additive.
[0049] Example 6
[0050] The additive and the mixed texturing agent are prepared according to the method of Example 1 for texturing reaction, except that the additive is composed of 0.03% by mass of vinyl pyrrolidone-methyl methacrylate copolymer (molecular weight 738500 g / mol) as a nucleating agent, 0.07% of 2-nitroaniline-4-sodium sulfonate as an auxiliary nucleating agent, 0.19% of polyvinyl alcohol as a dispersant, 0.8% of sodium dihydrogen phosphate as a corrosion inhibitor, and the remainder of deionized water and then mixed evenly to form the additive.
[0051] Example 7
[0052] The additive and the mixed texturing agent are prepared according to the method of Example 1 for texturing reaction, except that the additive is prepared by uniformly mixing 0.05% by mass of vinyl pyrrolidone-maleic anhydride copolymer (molecular weight 522500 g / mol) as a nucleating agent, 0.09% by mass of p-nitrobenzoic acid as an auxiliary nucleating agent, 0.2% by mass of polymannose as a dispersant, 0.5% by mass of sodium acetate as a corrosion inhibitor, and the remainder of deionized water.
[0053] Comparative Example 1
[0054] The additives and the mixed texturing agent were prepared according to the method of Example 1 to carry out texturing reaction, except that the additives used were conventional texturing additives currently available on the market (Shichuang V series texturing additives).
[0055] The micrograph of the silicon wafer texture obtained in Example 1 is as follows Figure 1 As shown, the micrograph of the silicon wafer texture surface obtained by Comparative Example 1 is as follows Figure 2 The velvet pyramid size distribution data obtained after the reaction of Example 1 to Example 7 with Comparative Example 1 is shown in Table 1, and the reflectivity data is shown in Table 2. Combining the data in Table 1 and Table 2, by comparing Figure 1 and Figure 2It can be concluded that the size distribution of the pyramids on the surface of silicon wafers made using conventional texturing additives on the market is uneven, with a high proportion of small-sized pyramids, obvious fine and broken lint on the surface, and a high reflectivity. However, the distribution of the pyramids on the surface of silicon wafers made using the texturing additives of the present invention is more uniform, with significantly less broken lint, and a lower reflectivity.
[0056] Table 1
[0057] Pyramid size range (um) 0.1-0.5 0.5-1.0 1.0-1.5 1.5-2.0 2.0-2.5 2.5-3.0 3.0-3.5 Example 1 Number of pyramids 2 26 93 163 105 12 3 Example 2 Number of pyramids 3 15 113 178 98 16 2 Example 3 Number of Pyramids 8 13 125 185 112 21 5 Example 4 Number of Pyramids 6 19 106 192 107 21 6 Example 5 Number of Pyramids 5 23 97 183 102 18 1 Example 6 Number of Pyramids 7 25 103 193 95 17 3 Example 7 Number of Pyramids 2 21 109 186 110 11 5 Comparative Example 1 Number of Pyramids 53 76 112 146 65 23 2
[0058] Table 2
[0059] additive Reflectivity(%) Example 1 8.24 Example 2 7.97 Example 3 8.13 Example 4 8.09 Example 5 8.15 Example 6 7.93 Example 7 8.02 Comparative Example 1 9.17
[0060] Example 8
[0061] Preparation of additives: The additives are prepared by uniformly mixing 0.06% by mass of vinyl pyrrolidone-styrene copolymer (molecular weight 21500 g / mol) as a main nucleating agent, 0.05% by mass of sodium p-nitrobenzene sulfonate as an auxiliary nucleating agent, 0.2% by mass of alkyl polyglucoside as a dispersant, 0.5% by mass of sodium chloride as a corrosion inhibitor, and the remainder by mass of deionized water.
[0062] Add 450L of deionized water to a 500L texturing reaction tank, heat the temperature to 76°C, add 3.38L of 45% NaOH solution, mix well to get a 0.5% alkaline solution, then add 1.5L of the additive prepared in the above steps to the alkaline solution, circulate and mix well inside the tank to get a mixed texturing agent. Then immerse the silicon wafer in the tank for 380s of texturing reaction. After the texturing reaction is completed, the silicon wafer enters the subsequent battery process preparation process, and finally makes a battery cell, and the electrical performance indicators and reflectivity of the battery cell are tested.
[0063] Comparative Example 2
[0064] Add 450L of deionized water to a 500L texturing reaction tank, heat the temperature to 76°C, then add 3.38L of 45% NaOH solution, mix well to get a 0.5% alkaline solution, then add the conventional texturing additives currently available on the market (Shichuang V series texturing additives) to the alkaline solution, circulate and mix well inside the tank to get a mixed texturing agent. Then immerse the silicon wafer in the tank for a texturing reaction of 380s. After the texturing reaction is completed, the silicon wafer enters the subsequent battery process preparation process, and finally makes a battery cell, and the electrical performance indicators and reflectivity of the battery cell are tested.
[0065] Table 3 shows the average electrical performance data and reflectivity of 1200 cells obtained after the texturing reaction in Example 8 and Comparative Example 2. According to the data in Table 3, it can be concluded that compared with conventional texturing additives, the cells made using the texturing additives of the present invention can effectively reduce the reflectivity, improve the fill factor and short-circuit current, and increase the average conversion efficiency of the cells by about 0.45%. This is mainly due to the fact that a more uniform velvet surface can improve the contact passivation effect of the subsequent coating process, thereby improving the overall efficiency of the cells to a certain extent.
[0066] Table 3
[0067] additive Efficiency Eta (%) Open circuit voltage Voc Short circuit current Isc Fill Factor FF Reflectivity(%) Example 8 26.97 0.7362 14.352 86.52 8.16 Comparative Example 2 26.52 0.7358 14.125 86.13 9.24
[0068] The above content only describes representative embodiments of the present invention and does not limit the protection scope of the present invention. It should be emphasized that various modifications and optimizations made by technicians in this field without violating the technical principles of the present invention are within the protection scope of the present invention.
Claims
1. A texturing additive for improving the efficiency of solar cells, characterized in that: The texturing additive comprises the following components in percentage by mass: 0.01%-0.1% of a main nucleating agent, 0.05%-0.2% of an auxiliary nucleating agent, 0.05%-0.5% of a dispersant, 0.5%-1% of a corrosion inhibitor, and the remainder being water; the main nucleating agent is a copolymer containing a vinyl pyrrolidone unit structure, and the auxiliary nucleating agent is a compound containing a nitrobenzene structure.
2. The texturing additive for improving the efficiency of solar cells according to claim 1, characterized in that: The structural formula of the primary nucleating agent is as follows: Wherein, R is selected from vinyl alcohol, styrene, vinylimidazole, hexadecene, isopropylacrylamide, methacrylamide, acrylamide, methyl methacrylate, acrylic acid, vinyl acetate, butyl acrylate, methacrylic acid or maleic anhydride structural units; n in the structural formula represents the number of vinylpyrrolidone structural units contained in the copolymer, and the molecular weight of the copolymer ranges from 20000 to 1000000 g / mol.
3. The texturing additive for improving the efficiency of solar cells according to claim 1, characterized in that: The structural formula of the auxiliary nucleating agent is as follows: Wherein, R1, R2, R3, R4, and R5 are independently selected from H, halogen, alkyl, alkoxy, amine, amide, aldehyde, hydrazine, sulfonic acid / sulfonate, phenol / phenolate, carboxyl, or ester.
4. The texturing additive for improving the efficiency of solar cells according to claim 3, wherein R1, R2, R3, R4, and R5 are independently selected from H, halogen, C1-C10 alkyl, -NH2, -(CH2) m CONH2, -(CH2) p CHO, -NHNH2, -SO3R6, -OR7 or -COOR8, wherein m, p are both natural numbers, and m=0-5, p=0-5, R6 is selected from H or a metal atom, and R7 and R8 are independently selected from H, a metal atom or a C1-C5 alkyl group; Preferably, R1, R2, R3, R4, and R5 are independently selected from H, halogen, C1-C3 alkyl, -NH2, -CONH2, -CHO, -NHNH2, -SO3R6, -OR7, and -COOR8; R6 is selected from H, Na or K, and R7 and R8 are independently selected from H, Na, K or C1-C2 alkyl; at least three of R1, R2, R3, R4, and R5 are selected from H.
5. The texturing additive for improving the efficiency of solar cells according to claim 1, characterized in that: The dispersant is selected from sodium lignin sulfonate, alkyl polyglucoside, sodium polymethacrylate, sulfonated polystyrene, polyvinyl alcohol, sodium polyacrylate or a polysaccharide compound, or a combination thereof; wherein the structural formula of the polysaccharide compound is (C6H 10 O5) n In this structural formula, C6H 10 O5 represents a monosaccharide unit after removing a water molecule, and n represents the number of monosaccharide units in the polysaccharide; preferably, the polysaccharide compound is selected from maltose, carrageenan, starch, lactose, cellulose, chitin, xanthan gum, inulin, polymannan or polyxylose; The corrosion inhibitor is selected from one or a combination of sodium chloride, sodium dihydrogen phosphate, sodium carbonate, sodium citrate, sodium acetate, and sodium silicate.
6. The method for preparing the texturing additive for improving the efficiency of solar cells according to any one of claims 1 to 5, characterized in that: The following steps are involved: According to the mass percentage, the main nucleating agent, the auxiliary nucleating agent, the dispersant and the corrosion inhibitor are added into water, and stirred and mixed evenly to obtain the product.
7. Use of the texturing additive according to any one of claims 1 to 5 in texturing of silicon wafers.
8. The use according to claim 7, characterized in that: The texturing additive is used in the texturing reaction of silicon wafers and can improve the efficiency of solar cells.
9. The use according to claim 7, characterized in that: The applications include: (1) dissolving soda ash in water and mixing evenly to obtain an alkaline solution, and then adding the texturing additive to the prepared alkaline solution and mixing evenly to prepare a mixed texturing agent; (2) Immerse the silicon wafer in the mixed texturing agent to carry out texturing reaction.
10. The use according to claim 9, characterized in that: In step (1), the alkali is selected from NaOH or KOH; the mass concentration of the alkali solution is 0.5%-1%; the mass ratio of the texturing additive to the alkali solution is 0.3-0.8:100; In step (2), the temperature of the texturing reaction is controlled between 75-85°C, and the reaction time is between 350s-450s.