Monocrystalline silicon alkaline polishing additive for TOPCon battery and use method of monocrystalline silicon alkaline polishing additive

Abstract

The invention belongs to the technical field of monocrystalline silicon polishing, and particularly discloses a TOPCon battery monocrystalline silicon alkali polishing additive which comprises the following components in percentage by mass: 3%-5% of a polishing agent, 0.1%-0.5% of a protective agent, 0.4%-2% of an anti-settling agent, 1%-3% of a defoaming agent and the balance of deionized water. The invention provides a TOPCon cell monocrystalline silicon alkali polishing additive and a use method thereof, the additive can realize polishing treatment of monocrystalline silicon under lower weight loss, and is suitable for TOPCon flaking, and the back surface of the polished monocrystalline silicon has higher reflectivity, so that the conversion efficiency of a solar cell is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of single crystal silicon polishing, and in particular relates to a TOPCon battery single crystal silicon alkaline polishing additive and a use method thereof. Background Art

[0002] TOPCon cells (tunneling oxide passivation contact cells) are an advanced solar cell technology. The core of the cell is to use the selective carrier principle to achieve efficient passivation and selective carrier collection on the back surface of bifacial solar cells through a tunneling oxide passivation contact structure. This contact structure consists of an ultra-thin oxide layer and a heavily doped polysilicon layer, which brings significant advantages to TOPCon cells in terms of thinning, thereby helping to reduce the cost of silicon wafers. However, in the preparation process of TOPCon cells, alkaline polishing has the advantages of low cost and high efficiency compared to acid polishing. However, alkaline polishing often has problems such as incomplete polishing, slow efficiency improvement, and easy damage to the front PN junction (i.e., BSG layer) of monocrystalline silicon, which directly affects the quality of the product. Therefore, alkaline polishing additives are often added during the alkaline polishing process. Existing alkaline polishing additives generally have technical defects such as insufficient stability, poor flatness, and poor polishing effect under low weight loss. This greatly limits the further improvement of the photoelectric conversion efficiency of the cell, thereby affecting the overall performance and market competitiveness of TOPCon cells.

[0003] At present, invention patent CN118374230B discloses a low-weight-loss single-crystal silicon alkali polishing additive suitable for TOPCon thinning and a method of using the same, comprising the following components: polishing active ingredient, meso-tetramethyl-meso-tetra-p-aminophenyl cup pyrrole, surfactant, tetrahydroxymethyl glycoluril, hexamethylenetetramine, 3,3'-disulfonic acid-4,4'-difluorophenyl sulfone disodium salt, N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid sodium, water-soluble polymerized cyclodextrin, brightener, dispersant, protective agent and deionized water; however, the use of the alkali polishing additive for TOPCon battery single-crystal silicon alkali polishing still has technical problems such as incomplete alkali polishing, efficiency needs to be further improved, polishing effect under low weight loss needs to be further improved, and it is difficult to adapt to the TOPCon thinning requirements. Summary of the invention

[0004] The purpose of the present invention is to overcome the above problems existing in the prior art and to provide a TOPCon cell single crystal silicon alkaline polishing additive and a method of using the same. The additive can achieve polishing of single crystal silicon at a lower weight loss and is suitable for TOPCon thinning. The back of the single crystal silicon has a higher reflectivity after polishing, thereby improving the conversion efficiency of the solar cell.

[0005] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0006] In a first aspect, the present invention provides a TOPCon cell monocrystalline silicon alkaline polishing additive, which comprises the following components, calculated by mass percentage: 3%-5% polishing agent, 0.1%-0.5% protective agent, 0.4%-2% anti-settling agent, 1%-3% defoaming agent, and the balance is deionized water.

[0007] Furthermore, the polishing agent is one or more of persulfate, borate, carbonate, and pyrophosphate.

[0008] Furthermore, the protective agent is one or more of imidazolyl ionic liquid, pyrrolyl ionic liquid and pyridinium ionic liquid.

[0009] Further, the imidazolyl ionic liquid is one or more of 1-vinyl-3-butyl imidazolium chloride, 1-butyl-3-methylimidazolium dicyanamide, and 1-ethylimidazolium chloride;

[0010] The pyrrolyl ionic liquid is one or more of 1-butyl-1-methylpyrrolidine trifluoromethanesulfonate, 1-butyl-1-methylpyrrolidine bis(trifluoromethanesulfonyl)imide, and N-butyl-N-methylpyrrolidine chloride;

[0011] The pyridinium-based ionic liquid is one or more of N-ethylpyridinium chloride, N-ethylpyridinium bromide, N-butylpyridinium chloride, and N-butylpyridinium bromide.

[0012] Furthermore, the anti-settling agent is one or more of sodium tartrate, zinc sulfate, 2,4,6-tris(aminocaproic acid)-1,3,5-triazine, 2-amino-1,3,5-triazine, polyepoxysuccinic acid, acrylic acid-sulfonate copolymer, acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer, polyacrylic acid, and maleic acid acrylate copolymer.

[0013] Furthermore, the anti-settling agent is obtained by mixing sodium tartrate, 2,4,6-tris(aminocaproic acid)-1,3,5-triazine and acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer in a mass ratio of 2:(1-7):5.

[0014] Furthermore, the defoaming agent is a water-soluble polysaccharide.

[0015] Furthermore, the water-soluble polysaccharide is one or more of hydroxymethyl cellulose, sodium carboxymethyl cellulose, sodium alginate, carboxymethyl chitosan, rhamnose, and sophorose.

[0016] In a second aspect, the present invention provides a method for using a TOPCon cell single crystal silicon alkali polishing additive, the method comprising the following steps:

[0017] Step S1, according to the raw material formula of TOPCon battery single crystal silicon alkali polishing additive, weigh the raw materials, mix the raw materials evenly, and obtain the TOPCon battery single crystal silicon alkali polishing additive;

[0018] Step S2, adding the TOPCon battery single crystal silicon alkaline polishing additive obtained in step S1 into the alkaline solution and stirring evenly to obtain a polishing solution;

[0019] Step S3, using the polishing liquid obtained in step S2 to polish the single crystal silicon.

[0020] Further, in step S2, the alkali solution is a NaOH solution or a KOH solution;

[0021] The mass concentration of the alkali solution is 4-6%.

[0022] Furthermore, in step S2, the mass ratio of the additive to the alkali solution is (12-17):360.

[0023] Furthermore, in step S3, the polishing treatment temperature is 55-70° C., and the polishing treatment time is 2-4 min.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The TOPCon cell single crystal silicon alkaline polishing additive provided by the present invention comprises a polishing agent, a protective agent, an anti-settling agent, and a defoaming agent in its raw material composition, and the components interact with each other; the alkaline polishing additive can realize the polishing treatment of single crystal silicon at a relatively low weight loss, is suitable for TOPCon thinning, and the back side of the single crystal silicon has a higher reflectivity after polishing, thereby improving the conversion efficiency of the solar cell.

[0026] 2. In the TOPCon battery single crystal silicon alkaline polishing additive provided by the present invention, one or more of imidazolyl ionic liquid, pyrrolyl ionic liquid and pyridine ionic liquid are used as protective agents. Imidazole ionic liquid, pyrrolyl ionic liquid and pyridine ionic liquid have excellent chemical stability and special chemical structure, and interact with the borosilicate glass layer on the surface of the silicon wafer to form a protective film on the surface of the borosilicate glass layer to protect the PN junction (BSG layer) on the front side of the silicon wafer from being destroyed, thereby preventing the alkaline polishing agent from excessively corroding the silicon wafer.

[0027] 3. Among the TOPCon battery single crystal silicon alkaline polishing additives provided by the present invention, a mixture of sodium tartrate, 2,4,6-tris(aminocaproic acid)-1,3,5-triazine and acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer is further preferably used as an anti-settling agent. The three work together to effectively complex the protective agent in the polishing liquid, avoid the protective agent from precipitating and adsorbing on the surface of the back silicon wafer, and ensure the cleanliness and stability of the polishing liquid.

[0028] 4. The present invention discloses a method for using a TOPCon battery single crystal silicon alkaline polishing additive, which has a simple process, convenient operation, good alkaline polishing effect, high reflectivity, no pollution in the alkaline polishing process, controllable tower base structure size, and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0030] Figure 1 This is a BSG state diagram of the boron expansion sheet after polishing provided in Example 1 of the present invention under a metallographic microscope;

[0031] Figure 2 This is a BSG state diagram of the boron expansion sheet after polishing provided in Comparative Example 1 of the present invention under a metallographic microscope;

[0032] Figure 3 This is a BSG state diagram of the boron expansion sheet after polishing provided in Comparative Example 2 of the present invention under a metallographic microscope;

[0033] Figure 4 This is a BSG state diagram of the boron expansion sheet after polishing provided in Comparative Example 3 of the present invention under a metallographic microscope;

[0034] Figure 5 This is a BSG state diagram of the boron expansion sheet after polishing provided in Comparative Example 4 of the present invention under a metallographic microscope;

[0035] Figure 6 is a state diagram of the polishing liquid provided in Example 1 of the present invention and Comparative Example 3 after being left to stand at room temperature for one day, Figure 6 In the figure, from left to right are respectively Example 1 and Comparative Example 3. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Example 1

[0038] This embodiment provides a TOPCon cell monocrystalline silicon alkaline polishing additive, which includes the following components, calculated by mass percentage: 3% polishing agent, 0.1% protective agent, 0.4% anti-settling agent, 1% degassing agent, and the balance is deionized water;

[0039] Among them, the polishing agent is sodium persulfate; the protective agent is 1-vinyl-3-butyl imidazole chloride; the anti-settling agent is obtained by mixing sodium tartrate and 2,4,6-tris(aminohexanoic acid)-1,3,5-triazine in a mass ratio of 2:3; and the defoaming agent is sodium alginate.

[0040] This embodiment also provides a method for using a TOPCon cell single crystal silicon alkaline polishing additive, comprising the following steps:

[0041] Step S1, according to the formula of the TOPCon battery single crystal silicon alkali polishing additive provided in this embodiment, weigh the raw materials, mix the raw materials evenly, and obtain the TOPCon battery single crystal silicon alkali polishing additive;

[0042] Step S2, mixing the TOPCon battery single crystal silicon alkaline polishing additive obtained in step S1 with the NaOH solution in a mass ratio of 12:360 and stirring evenly to obtain a polishing solution; wherein the mass concentration of the alkaline solution (i.e., the NaOH solution) is 4%;

[0043] Step S3, using the polishing liquid obtained in step S2 to polish the boron expanded wafer after the backside BSG is removed, the processing temperature is 55° C., and the processing time is 4 minutes.

[0044] Example 2

[0045] This embodiment provides a TOPCon cell monocrystalline silicon alkaline polishing additive, which includes the following components, calculated by mass percentage: 4% polishing agent, 0.3% protective agent, 1.2% anti-settling agent, 2% degassing agent, and the balance is deionized water;

[0046] Among them, the polishing agent is sodium borate; the protective agent is 1-butyl-1-methylpyrrolidino trifluoromethanesulfonate; the anti-settling agent is obtained by mixing sodium tartrate and polyacrylic acid in a mass ratio of 2:1; and the defoaming agent is hydroxymethyl cellulose.

[0047] This embodiment also provides a method for using a TOPCon cell single crystal silicon alkaline polishing additive, comprising the following steps:

[0048] Step S1, according to the formula of the TOPCon battery single crystal silicon alkali polishing additive provided in this embodiment, weigh the raw materials, mix the raw materials evenly, and obtain the TOPCon battery single crystal silicon alkali polishing additive;

[0049] Step S2, mixing the TOPCon battery single crystal silicon alkaline polishing additive obtained in step S1 with the NaOH solution in a mass ratio of 13:360 and stirring evenly to obtain a polishing solution; wherein the mass concentration of the alkaline solution (i.e., the NaOH solution) is 5%;

[0050] Step S3, using the polishing liquid obtained in step S2 to polish the boron expanded wafer after the backside BSG is removed, the processing temperature is 62.5° C., and the time is 3 minutes.

[0051] Example 3

[0052] This embodiment provides a TOPCon cell monocrystalline silicon alkaline polishing additive, which includes the following components, calculated by mass percentage: 5% polishing agent, 0.5% protective agent, 2% anti-settling agent, 3% degassing agent, and the balance is deionized water;

[0053] Among them, the polishing agent is sodium pyrophosphate; the protective agent is N-ethylpyridinium chloride; the anti-settling agent is obtained by mixing 2,4,6-tris(aminocaproic acid)-1,3,5-triazine and polyepoxysuccinic acid in a mass ratio of 1:3; and the defoaming agent is carboxymethyl chitosan.

[0054] This embodiment also provides a method for using a TOPCon cell single crystal silicon alkaline polishing additive, comprising the following steps:

[0055] Step S1, according to the formula of the TOPCon battery single crystal silicon alkali polishing additive provided in this embodiment, weigh the raw materials, mix the raw materials evenly, and obtain the TOPCon battery single crystal silicon alkali polishing additive;

[0056] Step S2, mixing the TOPCon battery single crystal silicon alkaline polishing additive obtained in step S1 with the KOH solution in a mass ratio of 17:360 and stirring evenly to obtain a polishing solution; wherein the mass concentration of the alkaline solution (i.e., the KOH solution) is 6%;

[0057] Step S3, using the polishing liquid obtained in step S2 to polish the boron expanded wafer after the backside BSG is removed, the processing temperature is 70° C., and the processing time is 2 minutes.

[0058] Example 4

[0059] This embodiment provides a TOPCon cell monocrystalline silicon alkaline polishing additive, which includes the following components, calculated by mass percentage: 3% polishing agent, 0.1% protective agent, 0.4% anti-settling agent, 1% degassing agent, and the balance is deionized water;

[0060] Among them, the polishing agent is sodium persulfate; the protective agent is 1-butyl-1-methylpyrrolidine bis(trifluoromethanesulfonyl)imide; the anti-settling agent is obtained by mixing sodium tartrate and 2,4,6-tris(aminocaproic acid)-1,3,5-triazine in a mass ratio of 2:3; and the defoaming agent is sodium alginate.

[0061] This embodiment also provides a method for using a TOPCon cell single crystal silicon alkaline polishing additive, comprising the following steps:

[0062] Step S1, according to the formula of the TOPCon battery single crystal silicon alkali polishing additive provided in this embodiment, weigh the raw materials, mix the raw materials evenly, and obtain the TOPCon battery single crystal silicon alkali polishing additive;

[0063] Step S2, mixing the TOPCon battery single crystal silicon alkaline polishing additive obtained in step S1 with the NaOH solution in a mass ratio of 12:360 and stirring evenly to obtain a polishing solution; wherein the mass concentration of the alkaline solution (i.e., the NaOH solution) is 4%;

[0064] Step S3, using the polishing liquid obtained in step S2 to polish the boron expanded wafer after the backside BSG is removed, the processing temperature is 55° C., and the processing time is 4 minutes.

[0065] Example 5

[0066] The present embodiment provides a TOPCon cell monocrystalline silicon alkaline polishing additive, which comprises the following components, calculated by mass percentage: 0.1% protective agent, 0.4% anti-settling agent, 1% degassing agent, 3% polishing agent, and the balance is deionized water.

[0067] Among them, the polishing agent is sodium persulfate; the protective agent is obtained by mixing 1-vinyl-3-butylimidazolium chloride and 1-butyl-1-methylpyrrolidine trifluoromethanesulfonate in a mass ratio of 1:1; the anti-settling agent is obtained by mixing sodium tartrate and 2,4,6-tris(aminohexanoic acid)-1,3,5-triazine in a mass ratio of 2:3; and the defoaming agent is sodium alginate.

[0068] This embodiment also provides a method for using a TOPCon cell single crystal silicon alkaline polishing additive, comprising the following steps:

[0069] Step S1, according to the formula of the TOPCon battery single crystal silicon alkali polishing additive provided in this embodiment, weigh the raw materials, mix the raw materials evenly, and obtain the TOPCon battery single crystal silicon alkali polishing additive;

[0070] Step S2, mixing the TOPCon battery single crystal silicon alkaline polishing additive obtained in step S1 with the NaOH solution in a mass ratio of 12:360 and stirring evenly to obtain a polishing solution; wherein the mass concentration of the alkaline solution (i.e., the NaOH solution) is 4%;

[0071] Step S3, using the polishing liquid obtained in step S2 to polish the boron expanded wafer after the backside BSG is removed, the processing temperature is 55° C., and the processing time is 4 minutes.

[0072] Example 6

[0073] The present embodiment provides a TOPCon cell monocrystalline silicon alkaline polishing additive, which comprises the following components, calculated by mass percentage: 3% polishing agent, 0.1% protective agent, 0.4% anti-settling agent, 1% degassing agent, and the balance is deionized water.

[0074] Among them, the polishing agent is sodium persulfate; the protective agent is 1-vinyl-3-butyl imidazole chloride; the anti-settling agent is obtained by mixing 2,4,6-tris(aminocaproic acid)-1,3,5-triazine and acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer in a mass ratio of 3:5; and the defoaming agent is sodium alginate.

[0075] This embodiment also provides a method for using a TOPCon cell single crystal silicon alkaline polishing additive, comprising the following steps:

[0076] Step S1, according to the formula of the TOPCon battery single crystal silicon alkali polishing additive provided in this embodiment, weigh the raw materials, mix the raw materials evenly, and obtain the TOPCon battery single crystal silicon alkali polishing additive;

[0077] Step S2, mixing the TOPCon battery single crystal silicon alkaline polishing additive obtained in step S1 with the NaOH solution in a mass ratio of 12:360 and stirring evenly to obtain a polishing solution; wherein the mass concentration of the alkaline solution (i.e., the NaOH solution) is 4%;

[0078] Step S3, using the polishing liquid obtained in step S2 to polish the boron expanded wafer after the backside BSG is removed, the processing temperature is 55° C., and the processing time is 4 minutes.

[0079] Example 7

[0080] The present embodiment provides a TOPCon cell monocrystalline silicon alkaline polishing additive, which comprises the following components, calculated by mass percentage: 3% polishing agent, 0.1% protective agent, 0.4% anti-settling agent, 1% degassing agent, and the balance is deionized water.

[0081] Among them, the polishing agent is sodium persulfate; the protective agent is 1-vinyl-3-butyl imidazole chloride; the anti-settling agent is obtained by mixing sodium tartrate and acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer in a mass ratio of 2:5; and the defoaming agent is sodium alginate.

[0082] This embodiment also provides a method for using a TOPCon cell single crystal silicon alkaline polishing additive, comprising the following steps:

[0083] Step S1, according to the formula of the TOPCon battery single crystal silicon alkali polishing additive provided in this embodiment, weigh the raw materials, mix the raw materials evenly, and obtain the TOPCon battery single crystal silicon alkali polishing additive;

[0084] Step S2, mixing the TOPCon battery single crystal silicon alkaline polishing additive obtained in step S1 with the NaOH solution in a mass ratio of 12:360 and stirring evenly to obtain a polishing solution; wherein the mass concentration of the alkaline solution (i.e., the NaOH solution) is 4%;

[0085] Step S3, using the polishing liquid obtained in step S2 to polish the boron expanded wafer after the backside BSG is removed, the processing temperature is 55° C., and the processing time is 4 minutes.

[0086] Example 8

[0087] The present embodiment provides a TOPCon cell monocrystalline silicon alkaline polishing additive, which comprises the following components, calculated by mass percentage: 3% polishing agent, 0.1% protective agent, 0.4% anti-settling agent, 1% degassing agent, and the balance is deionized water.

[0088] Among them, the polishing agent is sodium persulfate; the protective agent is 1-vinyl-3-butyl imidazole chloride; the anti-settling agent is obtained by mixing sodium tartrate, 2,4,6-tris(aminocaproic acid)-1,3,5-triazine and acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer in a mass ratio of 2:3:5; and the defoaming agent is sodium alginate.

[0089] This embodiment also provides a method for using a TOPCon cell single crystal silicon alkaline polishing additive, comprising the following steps:

[0090] Step S1, according to the formula of the TOPCon battery single crystal silicon alkali polishing additive provided in this embodiment, weigh the raw materials, mix the raw materials evenly, and obtain the TOPCon battery single crystal silicon alkali polishing additive;

[0091] Step S2, mixing the TOPCon battery single crystal silicon alkaline polishing additive obtained in step S1 with the NaOH solution in a mass ratio of 12:360 and stirring evenly to obtain a polishing solution; wherein the mass concentration of the alkaline solution (i.e., the NaOH solution) is 4%;

[0092] Step S3, using the polishing liquid obtained in step S2 to polish the boron expanded wafer after the backside BSG is removed, the processing temperature is 55° C., and the processing time is 4 minutes.

[0093] Comparative Example 1

[0094] This comparative example provides a TOPCon battery single crystal silicon alkali polishing additive, which is different from Example 1 only in that an equal mass of sodium tripolyphosphate is used to replace 1-vinyl-3-butyl imidazole chloride. The details are as follows:

[0095] This comparative example provides a TOPCon battery monocrystalline silicon alkaline polishing additive, which includes the following components, calculated by mass percentage: 3% polishing agent, 0.1% sodium tripolyphosphate, 0.4% anti-settling agent, 1% degassing agent, and the balance is deionized water;

[0096] Among them, the polishing agent is sodium persulfate; the anti-settling agent is obtained by mixing sodium tartrate and 2,4,6-tris(aminocaproic acid)-1,3,5-triazine in a mass ratio of 2:3; and the defoaming agent is sodium alginate.

[0097] This comparative example also provides a method for using a TOPCon battery single crystal silicon alkaline polishing additive, comprising the following steps:

[0098] Step S1, according to the formula of the TOPCon battery single crystal silicon alkali polishing additive provided in this comparative example, weigh the raw materials, mix the raw materials evenly, and obtain the TOPCon battery single crystal silicon alkali polishing additive;

[0099] Step S2, mixing the TOPCon battery single crystal silicon alkaline polishing additive obtained in step S1 with the NaOH solution in a mass ratio of 12:360 and stirring evenly to obtain a polishing solution; wherein the mass concentration of the alkaline solution (i.e., the NaOH solution) is 4%, and the mass fraction of the TOPCon battery single crystal silicon alkaline polishing additive in the polishing solution is 3%;

[0100] Step S3, using the polishing liquid obtained in step S2 to polish the boron expanded wafer after the backside BSG is removed, the processing temperature is 55° C., and the processing time is 4 minutes.

[0101] Comparative Example 2

[0102] This comparative example provides a TOPCon battery single crystal silicon alkali polishing additive, which is different from Example 1 only in that an equal mass of benzotriazole is used to replace the anti-settling agent (a mixture of sodium tartrate and 2,4,6-tris(aminocaproic acid)-1,3,5-triazine in a mass ratio of 2:3). The details are as follows:

[0103] This comparative example provides a TOPCon cell monocrystalline silicon alkaline polishing additive, which comprises the following components, calculated by mass percentage: 3% polishing agent, 0.1% protective agent, 0.4% benzotriazole, 1% degassing agent, and the balance is deionized water;

[0104] The polishing agent is sodium persulfate; the protective agent is 1-vinyl-3-butyl imidazole chloride; and the defoaming agent is sodium alginate.

[0105] This comparative example also provides a method for using a TOPCon battery single crystal silicon alkaline polishing additive, comprising the following steps:

[0106] Step S1, according to the formula of the TOPCon battery single crystal silicon alkali polishing additive provided in this comparative example, weigh the raw materials, mix the raw materials evenly, and obtain the TOPCon battery single crystal silicon alkali polishing additive;

[0107] Step S2, mixing the TOPCon battery single crystal silicon alkaline polishing additive obtained in step S1 with the NaOH solution in a mass ratio of 12:360 and stirring evenly to obtain a polishing solution; wherein the mass concentration of the alkaline solution (i.e., the NaOH solution) is 4%, and the mass fraction of the TOPCon battery single crystal silicon alkaline polishing additive in the polishing solution is 3%;

[0108] Step S3, using the polishing liquid obtained in step S2 to polish the boron expanded wafer after the backside BSG is removed, the processing temperature is 55° C., and the processing time is 4 minutes.

[0109] Comparative Example 3

[0110] This comparative example provides a TOPCon cell monocrystalline silicon alkali polishing additive, which is different from Example 1 only in that an equal-quality protective agent is used to replace the anti-settling agent. The details are as follows:

[0111] This comparative example provides a TOPCon cell monocrystalline silicon alkaline polishing additive, which comprises the following components, calculated by mass percentage: 3% polishing agent, 0.5% protective agent, 1% degassing agent, and the balance is deionized water;

[0112] The polishing agent is sodium persulfate; the protective agent is 1-vinyl-3-butyl imidazole chloride; and the defoaming agent is sodium alginate.

[0113] This comparative example also provides a method for using a TOPCon battery single crystal silicon alkaline polishing additive, comprising the following steps:

[0114] Step S1, according to the formula of the TOPCon battery single crystal silicon alkali polishing additive provided in this comparative example, weigh the raw materials, mix the raw materials evenly, and obtain the TOPCon battery single crystal silicon alkali polishing additive;

[0115] Step S2, mixing the TOPCon battery single crystal silicon alkaline polishing additive obtained in step S1 with the NaOH solution in a mass ratio of 12:360 and stirring evenly to obtain a polishing solution; wherein the mass concentration of the alkaline solution (i.e., the NaOH solution) is 4%, and the mass fraction of the TOPCon battery single crystal silicon alkaline polishing additive in the polishing solution is 3%;

[0116] Step S3, using the polishing liquid obtained in step S2 to polish the boron expanded wafer after the backside BSG is removed, the processing temperature is 55° C., and the processing time is 4 minutes.

[0117] Comparative Example 4

[0118] This comparative example provides a TOPCon cell monocrystalline silicon alkali polishing additive, which is different from Example 1 only in that an anti-settling agent of equal mass is used to replace the protective agent. The details are as follows:

[0119] This comparative example provides a TOPCon battery monocrystalline silicon alkaline polishing additive, which includes the following components calculated by mass percentage: 3% polishing agent, 0.5% anti-settling agent, 1% degassing agent, and the balance is deionized water;

[0120] Among them, the polishing agent is sodium persulfate; the anti-settling agent is obtained by mixing sodium tartrate and 2,4,6-tris(aminocaproic acid)-1,3,5-triazine in a mass ratio of 2:3; and the defoaming agent is sodium alginate.

[0121] This comparative example also provides a method for using a TOPCon battery single crystal silicon alkaline polishing additive, comprising the following steps:

[0122] Step S1, according to the formula of the TOPCon battery single crystal silicon alkali polishing additive provided in this comparative example, weigh the raw materials, mix the raw materials evenly, and obtain the TOPCon battery single crystal silicon alkali polishing additive;

[0123] Step S2, mixing the TOPCon battery single crystal silicon alkaline polishing additive obtained in step S1 with the NaOH solution in a mass ratio of 12:360 and stirring evenly to obtain a polishing solution; wherein the mass concentration of the alkaline solution (i.e., the NaOH solution) is 4%, and the mass fraction of the TOPCon battery single crystal silicon alkaline polishing additive in the polishing solution is 3%;

[0124] Step S3, using the polishing liquid obtained in step S2 to polish the boron expanded wafer after the backside BSG is removed, the processing temperature is 55° C., and the processing time is 4 minutes.

[0125] Performance Testing

[0126] The boron expansion sheet provided in the method of using the TOPCon battery single crystal silicon alkaline polishing additive involved in Examples 1-8 and Comparative Examples 1-4 was subjected to relevant performance tests, and the test results are shown in Table 1;

[0127] Among them, if the corrosion degree of the BSG layer under the metallographic microscope is "none", it is evaluated as A; if the corrosion degree of the BSG layer under the metallographic microscope is "slight", it is evaluated as B; if the corrosion degree of the BSG layer under the metallographic microscope is "slightly heavy", it is evaluated as C; if the corrosion degree of the BSG layer under the metallographic microscope is "heavy", it is evaluated as D;

[0128] The reflectivity test system is used to measure the integrated reflectivity within the wavelength range of 300-1100nm; the weight loss is counted and calculated.

[0129] Table 1

[0130]

[0131]

[0132] The polishing data of Examples 1-8 and Comparative Examples 1-4 are shown in Table 1. From the weight loss data and reflectivity in Table 1, it can be seen that the additive of the present invention can achieve the effect of low weight loss and higher back reflectivity.

[0133] The state of BSG under the metallographic microscope after polishing of Example 1 and Comparative Examples 1-4 is as follows Figure 1-5 As shown, from Figure 1-5 It can be seen that the front BSG layer of Example 1 is not corroded; the front BSG layer of Comparative Example 1 is slightly corroded; the front BSG layer of Comparative Example 2 is corroded to form a gap, with a small tower base in the gap; half of the front BSG layer of Comparative Example 3 is corroded away, and the other half is the tower base; the front BSG layer of Comparative Example 4 is completely corroded, and is entirely the tower base; the additive of the present invention can protect the front BSG layer from being damaged.

[0134] The polishing liquids of Example 1 and Comparative Example 3 were left standing at room temperature for one day. Figure 6 shown, specifically, Figure 6 In the figure, the polishing liquid of Comparative Example 3 is on the right, which is turbid and opaque as a whole, while Figure 6 In the figure, the left side is the polishing liquid of Example 1, which is still clear and transparent, proving that the anti-settling agent in the additive of the present invention can more effectively prevent the protective agent from precipitating and ensure the cleanliness of the polishing liquid.

[0135] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0136] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A TOPCon battery single crystal silicon alkali polishing additive, characterized in that: Calculated by mass percentage, the composition includes: 3%-5% polishing agent, 0.1%-0.5% protective agent, 0.4%-2% anti-settling agent, 1%-3% defoaming agent, and the balance is deionized water.

2. A TOPCon battery single crystal silicon alkali polishing additive according to claim 1, characterized in that: The polishing agent is one or more of persulfate, borate, carbonate and pyrophosphate.

3. A TOPCon battery single crystal silicon alkali polishing additive according to claim 1, characterized in that: The protective agent is one or more of imidazolyl ionic liquid, pyrrolyl ionic liquid and pyridyl ionic liquid.

4. A TOPCon battery single crystal silicon alkali polishing additive according to claim 3, characterized in that: The imidazolyl ionic liquid is one or more of 1-vinyl-3-butyl imidazolium chloride, 1-butyl-3-methyl imidazolium dicyanamide, and 1-ethyl imidazolium chloride; The pyrrolyl ionic liquid is one or more of 1-butyl-1-methylpyrrolidine trifluoromethanesulfonate, 1-butyl-1-methylpyrrolidine bis(trifluoromethanesulfonyl)imide, and N-butyl-N-methylpyrrolidine chloride; The pyridinium-based ionic liquid is one or more of N-ethylpyridinium chloride, N-ethylpyridinium bromide, N-butylpyridinium chloride, and N-butylpyridinium bromide.

5. The TOPCon battery single crystal silicon alkali polishing additive according to claim 1, characterized in that: The anti-settling agent is one or more of sodium tartrate, zinc sulfate, 2,4,6-tris(aminocaproic acid)-1,3,5-triazine, 2-amino-1,3,5-triazine, polyepoxysuccinic acid, acrylic acid-sulfonate copolymer, acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer, polyacrylic acid, and maleic acid acrylate copolymer.

6. A TOPCon battery single crystal silicon alkali polishing additive according to claim 5, characterized in that: The anti-settling agent is obtained by mixing sodium tartrate, 2,4,6-tris(aminocaproic acid)-1,3,5-triazine and acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer in a mass ratio of 2:(1-7):

5.

7. The TOPCon battery single crystal silicon alkali polishing additive according to claim 1, characterized in that: The defoaming agent is a water-soluble polysaccharide.

8. A method for using the TOPCon battery single crystal silicon alkaline polishing additive according to any one of claims 1 to 7, characterized in that: The method of use includes the following steps: Step S1, according to the raw material formula of TOPCon battery single crystal silicon alkali polishing additive, weigh the raw materials, mix the raw materials evenly, and obtain the TOPCon battery single crystal silicon alkali polishing additive; Step S2, adding the TOPCon battery single crystal silicon alkaline polishing additive obtained in step S1 into the alkaline solution and stirring evenly to obtain a polishing solution; Step S3, using the polishing liquid obtained in step S2 to polish the single crystal silicon.

9. The method for using a TOPCon battery single crystal silicon alkali polishing additive according to claim 8, characterized in that: In step S2, the alkali solution is a NaOH solution or a KOH solution; The mass concentration of the alkali solution is 4-6%.

10. The method for using a TOPCon battery single crystal silicon alkali polishing additive according to claim 8, characterized in that: In step S2, the mass ratio of the additive to the alkali solution is (12-17):360.

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