Photovoltaic copper antioxidant, preparation method and application thereof, crystalline silicon solar cell and preparation method thereof

Abstract

The invention provides a photovoltaic copper antioxidant, a preparation method and application of the photovoltaic copper antioxidant, a crystalline silicon solar cell and a preparation method of the crystalline silicon solar cell, and relates to the technical field of crystalline silicon solar cells. The photovoltaic copper antioxidant comprises the following components in parts by weight: 5-20 parts of a compound corrosion inhibitor; 50 to 200 parts of a dispersant; 0.5 to 2 parts of a surfactant; 0.2 to 1 part of a stabilizer; wherein the compound corrosion inhibitor comprises benzimidazole and imidazoline quaternary ammonium salt in a mass ratio of (1-2): (5-10). The photovoltaic copper antioxidant provided by the invention can quickly form a compact protective film with a regular structure on the surface of a copper grid line, can play a role of a barrier layer, enables the copper surface to be isolated from air and free from air oxidation, and a crystalline silicon solar cell treated by the photovoltaic copper antioxidant cannot discolor after being exposed in air and placed for a long time.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a photovoltaic copper antioxidant, a preparation method and application thereof, a crystalline silicon solar cell and a preparation method thereof. Background Art

[0002] Metallization is a key process in the manufacture of silicon solar cells. It is primarily used to create silicon solar cell electrodes, forming ohmic contacts at both ends of the PN junction to achieve current output. Currently, screen printing is the most mature and common metallization process, but the high cost of the silver paste used has become a significant factor limiting its widespread adoption. To further reduce the cost of silicon solar cells and improve cell efficiency, the possibility of mass-producing metal electrodes for crystalline silicon solar cells using electroplating has been explored. This method can replace silver with cheaper metals such as nickel, copper, and tin to achieve cost reductions.

[0003] Copper is similar to silver in conductivity and is relatively more affordable, making it more widely used in practical applications. Crystalline silicon solar cells using copper as the metal electrode are also an excellent choice. However, metallic copper is easily oxidized when exposed to air, and it is often necessary to deposit a layer of metallic tin on the copper surface through electroplating or chemical tin plating to protect it and improve the welding quality and reliability of crystalline silicon solar cells. However, because tin has a significantly higher resistivity than copper, its conductivity is relatively poor, resulting in a lower photoelectric conversion efficiency of the solar cell after tin plating, a decrease in short-circuit current, and thus a deterioration in electrical performance. Therefore, it is crucial to solve the oxidation problem of the copper grid line surface of solar cells.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a photovoltaic copper antioxidant and its preparation method and application, a crystalline silicon solar cell and its preparation method, wherein the photovoltaic copper antioxidant effectively solves the surface oxidation problem of the copper grid line of the crystalline silicon solar cell.

[0006] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0007] In a first aspect, the present invention provides a photovoltaic copper antioxidant, which comprises the following components in parts by weight:

[0008]

[0009] The compound corrosion inhibitor comprises benzimidazole and imidazoline quaternary ammonium salt in a mass ratio of (1-2): (5-10).

[0010] Preferably, the photovoltaic copper antioxidant comprises the following components by concentration:

[0011]

[0012] The compound corrosion inhibitor comprises benzimidazole and imidazoline quaternary ammonium salt in a mass ratio of (1-2): (5-10).

[0013] Preferably, the imidazoline quaternary ammonium salt is an imidazoline compound grafted with a quaternary ammonium compound; wherein the imidazoline compound is obtained by dehydration cyclization of lauric acid, xylene and triethylenetetramine.

[0014] Preferably, the quaternary ammonium compound includes any one or a combination of at least two of benzalkonium chloride, benzalkonium bromide, triethylammonium benzoate, cetyltrimethylammonium bromide, methylbenzenedimethylammonium chloride or tetramethylammonium hydroxide.

[0015] Preferably, the dispersant includes any one of C1-C5 monohydric alcohol, C2-C5 dihydric alcohol or C2-C5 trihydric alcohol, or a combination of at least two thereof.

[0016] Preferably, the dispersant includes any one of methanol, ethanol, propanol, ethylene glycol, isopropanol or glycerol, or a combination of at least two thereof.

[0017] Preferably, the surfactant includes any one of polyoxypropylene glycol, polytetramethylene glycol, polyoxyethylene alkyl alcohol amide or fatty alcohol polyoxyethylene ether, or a combination of at least two thereof.

[0018] Preferably, the stabilizer includes any one of butylated hydroxytoluene, dibutylated hydroxytoluene or butylated hydroxyanisole, or a combination of at least two thereof.

[0019] In a second aspect, the present invention provides a method for preparing the photovoltaic copper antioxidant as described in the first aspect, the preparation method comprising:

[0020] Dissolving the compound corrosion inhibitor in water containing a dispersant, and mixing for the first time to obtain a mixed solution;

[0021] A surfactant and a stabilizer are added to the mixed solution, and mixed for a second time to obtain the photovoltaic copper antioxidant.

[0022] Preferably, the temperature of the first mixing is 40-80° C.; the rotation speed of the first mixing is 300-600 rpm; and the time of the first mixing is 30-60 min.

[0023] Preferably, the temperature of the second mixing is 20-30° C.; the rotation speed of the second mixing is 500-1000 rpm; and the time of the second mixing is 30-60 min.

[0024] Preferably, after the second mixing, the method further comprises: adjusting the pH of the mixed solution to 3-5.

[0025] Preferably, the reagent for adjusting the pH of the mixed solution includes sulfuric acid and / or sodium hydroxide.

[0026] Preferably, the preparation method of the imidazoline quaternary ammonium salt in the compound corrosion inhibitor comprises:

[0027] Lauric acid and xylene are mixed and subjected to a dehydration reaction to obtain a first reaction liquid; triethylenetetramine is added to the first reaction liquid and subjected to a cyclization reaction to obtain a second reaction liquid; a quaternary ammonium compound is added to the second reaction liquid and subjected to a quaternization reaction to obtain the imidazoline quaternary ammonium salt.

[0028] Preferably, the mass ratio of lauric acid to xylene is 1:(1-4).

[0029] Preferably, the temperature of the dehydration reaction is 100-150° C.; and the time of the dehydration reaction is 1-3 hours.

[0030] Preferably, the mass ratio of lauric acid to triethylenetetramine is (1-2):(1-2).

[0031] Preferably, the first reaction solution needs to be heated to 160-220° C. before adding triethylenetetramine.

[0032] Preferably, the temperature of the cyclization reaction is 200-250° C.; and the time of the cyclization reaction is 2-4 hours.

[0033] Preferably, the dehydration reaction and cyclization reaction are carried out in the presence of a catalyst.

[0034] Preferably, the catalyst comprises alumina.

[0035] Preferably, the mass ratio of the lauric acid to the catalyst is 1:(0.01-0.1);

[0036] Preferably, the mass ratio of the lauric acid to the quaternary ammonium compound is (1-2):(1-1.5).

[0037] Preferably, the quaternary ammonium compound includes any one or a combination of at least two of benzalkonium chloride, benzalkonium bromide, triethylammonium benzoate, cetyltrimethylammonium bromide or tetramethylammonium hydroxide.

[0038] Preferably, the second reaction liquid needs to be concentrated before adding the quaternary ammonium compound; wherein the volume of the second reaction liquid after concentration accounts for 30-50% of the volume of the second reaction liquid before concentration.

[0039] Preferably, the concentrated second reaction liquid needs to be cooled to 80-100° C. before adding the quaternary ammonium compound.

[0040] Preferably, the temperature of the quaternization reaction is 80-120° C.; and the time of the quaternization reaction is 3-5 hours.

[0041] In a third aspect, the present invention provides a use of the photovoltaic copper antioxidant in the preparation of crystalline silicon solar cells.

[0042] In a fourth aspect, the present invention provides a crystalline silicon solar cell comprising a copper grid line and a protective film on the surface of the copper grid line; wherein the protective film is formed by the photovoltaic copper antioxidant as described in the first aspect.

[0043] In a fifth aspect, the present invention provides a method for preparing a crystalline silicon solar cell as described in the fourth aspect, the preparation method comprising:

[0044] The crystalline silicon solar cell is immersed in the photovoltaic copper antioxidant as described in the first aspect, and then washed and dried to obtain the crystalline silicon solar cell; wherein both sides of the crystalline silicon solar cell have copper grid lines.

[0045] Preferably, the immersion temperature is 30-60° C., and the immersion time is 1-5 minutes.

[0046] Preferably, the drying temperature is 60-90° C.; and the drying time is 4-8 minutes.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] (1) The photovoltaic copper antioxidant provided by the present invention can quickly form a structurally regular and dense protective film on the surface of the copper grid line, which can act as a barrier layer to isolate the copper surface from the air and prevent air oxidation. The crystalline silicon solar cell treated by the present invention will not change color when exposed to the air for one month.

[0049] (2) The protective film formed on the crystalline silicon solar cell by the copper antioxidant composed of a compound of benzimidazole and imidazoline quaternary ammonium salt of the present invention has good thermal stability. It can not only reduce the oxides formed on the surface of the copper grid line, but also promote the formation of a new protective film during the reduction process, thereby enhancing the antioxidant ability; in addition, in a high temperature environment of 300°C or above, high-temperature welding can be performed without being oxidized, and the weldability is good. DETAILED DESCRIPTION

[0050] Unless otherwise defined herein, scientific and technological terms used in conjunction with the present invention shall have the meanings commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear, however, in the case of any potential ambiguity, the definitions provided herein take precedence over any dictionary or external definitions. In this application, unless otherwise stated, the use of "or" means "and / or". In addition, the use of the term "including" and other forms is non-limiting.

[0051] It should be noted that the following description sets forth specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in a variety of other ways than those described herein, and those skilled in the art may make similar generalizations without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0052] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0053] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0054] In a first aspect, the present invention provides a photovoltaic copper antioxidant, which comprises the following components in parts by weight:

[0055]

[0056] The compound corrosion inhibitor comprises benzimidazole and imidazoline quaternary ammonium salt in a mass ratio of (1-2): (5-10).

[0057] In the present invention, the photovoltaic copper antioxidant contains a compound corrosion inhibitor, a dispersant, a surfactant and a stabilizer in a specific ratio. The components cooperate with each other to quickly form a structurally regular and dense protective film on the surface of the copper grid line, thereby acting as a barrier layer to isolate the copper surface from the air and prevent air oxidation. The crystalline silicon solar cell treated with the photovoltaic copper antioxidant of the present invention can be significantly prolonged in exposure to air and will not change color.

[0058] At the same time, the compound corrosion inhibitor of the present invention is composed of benzimidazole and imidazoline quaternary ammonium salt in a specific ratio. The two cooperate with each other, and chemical adsorption is combined with physical adsorption to ensure that the protective film formed by the photovoltaic copper antioxidant on the crystalline silicon solar cell can not only reduce the oxide formed on the surface of the copper grid line, but also promote the generation of a new protective film during the reduction process, thereby significantly enhancing the antioxidant ability, enabling high-temperature welding without being oxidized; and the formed protective film also has good thermal stability, and can be subjected to high-temperature welding without being oxidized in a high-temperature environment, and has good weldability.

[0059] As an optional embodiment, the content of the compound corrosion inhibitor in the photovoltaic copper antioxidant is 5 to 20 parts, for example, it can be 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, etc.

[0060] As an optional embodiment, the content of the dispersant in the photovoltaic copper antioxidant is 50 to 200 parts, for example, it can be 50 parts, 60 parts, 70 parts, 80 parts, 90 parts, 100 parts, 110 parts, 120 parts, 130 parts, 140 parts, 150 parts, 160 parts, 170 parts, 180 parts, 190 parts, 200 parts, etc.

[0061] As an optional embodiment, the content of the surfactant is 0.5 to 2 parts, for example, it can be 0.5 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, 2 parts, etc.

[0062] As an optional embodiment, the content of the stabilizer is 0.2 to 1 part, for example, it can be 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part, 1 part, etc.

[0063] As an optional embodiment, in the compound corrosion inhibitor, the mass ratio of the benzimidazole and the imidazoline quaternary ammonium salt is (1-2): (5-10);

[0064] Among them, "1-2" can be, for example, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, etc.; among them, "5-10" can be, for example, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, etc.

[0065] As an optional embodiment, the photovoltaic copper antioxidant comprises the following components by concentration:

[0066]

[0067] The compound corrosion inhibitor comprises benzimidazole and imidazoline quaternary ammonium salt in a mass ratio of (1-2): (5-10).

[0068] As an optional embodiment, the mass concentration of the compound corrosion inhibitor in the photovoltaic copper antioxidant is 5 to 20 g / L, for example, it can be 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L, 10 g / L, 11 g / L, 12 g / L, 13 g / L, 14 g / L, 15 g / L, 16 g / L, 17 g / L, 18 g / L, 19 g / L, 20 g / L, etc.

[0069] As an optional embodiment, the volume concentration of the dispersant in the photovoltaic copper antioxidant is 50 to 200 mL / L, for example, it can be 50 mL / L, 60 mL / L, 70 mL / L, 80 mL / L, 90 mL / L, 100 mL / L, 110 mL / L, 120 mL / L, 130 mL / L, 140 mL / L, 150 mL / L, 160 mL / L, 170 mL / L, 180 mL / L, 190 mL / L, 200 mL / L, etc.

[0070] As an optional embodiment, the mass concentration of the surfactant in the photovoltaic copper antioxidant is 0.5 to 2 g / L, for example, it can be 0.5 g / L, 0.6 g / L, 0.8 g / L, 1 g / L, 1.2 g / L, 1.4 parts, 1.5 g / L, 1.6 g / L, 1.8 g / L, 2 g / L, etc.

[0071] As an optional embodiment, the mass concentration of the stabilizer in the photovoltaic copper antioxidant is 0.2 to 1 g / L, for example, it can be 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L, 1 g / L, etc.

[0072] As an optional embodiment, the imidazoline quaternary ammonium salt is an imidazoline compound grafted with a quaternary ammonium compound; wherein the imidazoline compound is obtained by dehydration cyclization of lauric acid, xylene and triethylenetetramine.

[0073] In the present invention, the imidazoline quaternary ammonium salt is prepared by modifying imidazoline with a quaternary ammonium compound to introduce a nitrogen atom. The tertiary amine group in the imidazoline undergoes an alkylation reaction with a halogenated hydrocarbon or an epoxy compound to be converted into a quaternary ammonium salt, which makes it permanently positively charged, thereby improving its water solubility and the adsorption capacity of the negatively charged surface, and finally obtaining an imidazoline quaternary ammonium salt corrosion inhibitor.

[0074] As an optional embodiment, the quaternary ammonium compound includes any one or a combination of at least two of benzalkonium chloride, benzalkonium bromide, triethylammonium benzoate, cetyltrimethylammonium bromide, methylbenzenedimmonium chloride or tetramethylammonium hydroxide.

[0075] In the present invention, it is preferred that the imidazoline compound of the grafted quaternary ammonium compound is a quaternary ammonium salt as described above. The reasons are as follows: 1. The imidazoline compound generated by dehydration cyclization contains multiple nitrogen atoms, which can form a strong coordination bond (Cu-N bond) with the copper surface, covering the active site of copper and directly inhibiting oxidation reaction; 2. It has an imidazoline or macrocyclic polyamine structure, and triethylenetetramine is used as a polyamine precursor. After cyclization, it may form a chelating agent containing multiple coordination sites, and the multidentate coordination ability enhances the chelating effect with copper, which is more conducive to forming a dense chemical protective film on copper; 3. It has an alkyl group containing a C12 long chain, and lauric acid is used as a precursor. The alkyl chain is physically adsorbed or covalently linked to the imidazole ring, and the long carbon chain self-assembles on the copper surface to form a hydrophobic outer layer, effectively blocking water molecules and oxygen, forming a more closely arranged physical barrier, and reducing film defects. 4. It has a quaternary ammonium group, which enhances the adsorption strength of the molecule on the copper surface through electrostatic action, and the positively charged quaternary ammonium group repels the cationic corrosive medium in the solution, reducing the local electrochemical corrosion tendency. 5. It has a conjugated system such as imidazole ring, which improves the thermal stability of the molecule and enhances the mechanical strength and resistance to thermal decomposition of the film.

[0076] As an optional embodiment, the dispersant includes any one of C1-C5 monohydric alcohol, C2-C5 dihydric alcohol or C2-C5 trihydric alcohol, or a combination of at least two thereof.

[0077] As an optional embodiment, the dispersant includes any one of methanol, ethanol, propanol, ethylene glycol, isopropanol or glycerol, or a combination of at least two of them.

[0078] As a preferred embodiment, the dispersant includes a combination of ethanol and ethylene glycol, or a combination of isopropyl alcohol and glycerol.

[0079] As a preferred embodiment, the mass ratio of ethanol to ethylene glycol is (1-2):(1-2), for example, it can be 1:1, 1:1.2, 1:1.4, 1:1.5, 1:1.6, 1:1.8, 1:2, 2:1, 2:1.2, 2:1.4, 2:1.5, 2:1.6, 2:1.8, etc.

[0080] As a preferred embodiment, the mass ratio of isopropyl alcohol to glycerol is (1-2):(1-2), for example, it can be 1:1, 1:1.2, 1:1.4, 1:1.5, 1:1.6, 1:1.8, 1:2, 2:1, 2:1.2, 2:1.4, 2:1.5, 2:1.6, 2:1.8, etc.

[0081] In the present invention, the dispersant is preferably a combination of a monohydric alcohol (containing only a single hydroxyl group) and a polyhydric alcohol (a dihydric diol with a dihydroxy structure, a trihydric triol with a trihydroxy structure) in a specific ratio; the advantages of the combination of the two are: 1. The monohydric alcohol can increase the hydrophobic component (such as benzimidazole) in the photovoltaic copper antioxidant, preventing organic phase precipitation, while the polyhydric alcohol enhances the dispersibility of the water-soluble antioxidant (such as a quaternary ammonium salt), forming a uniform solution; thereby, through polarity gradient matching, hydrophobic / hydrophilic antioxidant co-dissolution is achieved, reducing phase separation. 2. The monohydric alcohol's osmotic regulation reduces the viscosity of the system, promotes the dispersion of antioxidant molecules to the copper surface, and improves the uniformity of coverage; while the polyhydric alcohol constructs a dynamic solvent structure through hydrogen bonds between hydroxyl groups, which is beneficial to improving the stabilization of the protective film.

[0082] As an optional embodiment, the surfactant includes any one of polyoxypropylene glycol, polytetramethylene glycol, polyoxyethylene alkyl alcohol amide or fatty alcohol polyoxyethylene ether, or a combination of at least two thereof.

[0083] As an optional embodiment, the surfactant consists of polyoxypropylene glycol and polyoxyethylene alkyl alcohol amide.

[0084] As an optional embodiment, the mass ratio of the polyoxypropylene glycol and the polyoxyethylene alkyl alcohol amide is (1-2):(1-2), for example, it can be 1:1, 1:1.2, 1:1.4, 1:1.5, 1:1.6, 1:1.8, 1:2, 2:1, 2:1.2, 2:1.4, 2:1.5, 2:1.6, 2:1.8, etc.

[0085] In the present invention, the surfactant is preferably a combination of polyoxypropylene glycol and polyoxyethylene alkyl alcohol amide in a specific ratio; the advantages of the combination of the two are: 1. The polyoxypropylene chain has strong hydrophobicity and can anchor the hydrophobic groups of the antioxidant (such as the benzimidazole aromatic ring) to prevent their agglomeration; the polyoxyethylene chain and the amide group give the molecule high hydrophilicity, promoting the dispersion of the antioxidant in the aqueous system; the two cooperate with each other to achieve hydrophilic-hydrophobic balance regulation, which helps the antioxidant to be directional adsorbed on the copper surface, forming a more dense and uniform protective film layer. 2. The ether bond (COC) of the polyoxypropylene glycol is resistant to high-temperature decomposition, protecting the solderability of the antioxidant under high-temperature welding; the polyoxyethylene alkyl alcohol amide maintains the high-temperature stability of the dispersed system through a dynamic hydrogen bond network.

[0086] As an optional embodiment, the stabilizer includes any one of butylated hydroxytoluene, dibutylated hydroxytoluene or butylated hydroxyanisole, or a combination of at least two thereof.

[0087] In a second aspect, the present invention provides a method for preparing the photovoltaic copper antioxidant as described in the first aspect, the preparation method comprising:

[0088] Dissolving the compound corrosion inhibitor in water containing a dispersant, and mixing for the first time to obtain a mixed solution;

[0089] A surfactant and a stabilizer are added to the mixed solution, and mixed for a second time to obtain the photovoltaic copper antioxidant.

[0090] As a preferred embodiment, the temperature of the first mixing is 40-80°C, for example, it can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, etc.; the rotation speed of the first mixing is 300-600rpm, for example, it can be 300rpm, 350rpm, 400rpm, 450rpm, 500rpm, 550rpm, 600rpm, etc.; the time of the first mixing is 30-60min, for example, it can be 30min, 35min, 40min, 45min, 50min, 55min, 60min, etc.

[0091] As a preferred embodiment, the temperature of the second mixing is 20-30°C, for example, it can be 20°C, 22°C, 24°C, 25°C, 26°C, 28°C, 30°C, etc.; the speed of the second mixing is 500-1000rpm, for example, it can be 500rpm, 600rpm, 700rpm, 800rpm, 900rpm, 1000rpm, etc.; the time of the second mixing is 30-60min, for example, it can be 30min, 35min, 40min, 45min, 50min, 55min, 60min, etc.

[0092] As an optional embodiment, after the second mixing, the further step includes: adjusting the pH of the mixed solution to 3-5, for example, 3, 3.2, 3.4, 3.5, 3.6, 3.8, 4, 4.2, 4.4, 4.5, 4.6, 4.8, 5, etc.

[0093] As an optional embodiment, the reagent for adjusting the pH of the mixed solution includes sulfuric acid and / or sodium hydroxide.

[0094] As an optional embodiment, the preparation method of the imidazoline quaternary ammonium salt in the composite corrosion inhibitor includes:

[0095] Lauric acid and xylene are mixed and subjected to a dehydration reaction to obtain a first reaction liquid; triethylenetetramine is added to the first reaction liquid and subjected to a cyclization reaction to obtain a second reaction liquid; a quaternary ammonium compound is added to the second reaction liquid and subjected to a quaternization reaction to obtain the imidazoline quaternary ammonium salt.

[0096] As an optional embodiment, the mass ratio of lauric acid to xylene is 1:(1-4), for example, it can be 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, etc.

[0097] As an optional embodiment, the temperature of the dehydration reaction is 100-150°C, for example, it can be 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, etc.

[0098] As an optional embodiment, the dehydration reaction time is 1 to 3 hours, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, etc.

[0099] As an optional embodiment, the mass ratio of lauric acid and triethylenetetramine is (1-2):(1-2), for example, it can be 1:1, 1:1.2, 1:1.4, 1:1.5, 1:1.6, 1:1.8, 1:2, 2:1, 2:1.2, 2:1.4, 2:1.5, 2:1.6, 2:1.8, etc.

[0100] As an optional embodiment, the first reaction liquid needs to be heated to 160-220°C (for example, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 200°C, 210°C, 215°C, 220°C, etc.) before adding triethylenetetramine.

[0101] As an optional embodiment, the temperature of the cyclization reaction is 200-250°C, for example, it can be 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C, 235°C, 240°C, 245°C, 250°C, etc.

[0102] As an optional embodiment, the cyclization reaction time is 2 to 4 hours, for example, it can be 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, 3 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours, 4 hours, etc.

[0103] As an optional embodiment, the dehydration reaction and cyclization reaction are carried out in the presence of a catalyst.

[0104] As an optional embodiment, the catalyst comprises alumina.

[0105] As an optional embodiment, the mass ratio of lauric acid to catalyst is 1:(0.01-0.1), for example, it can be 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, 1:0.1, etc.

[0106] As an optional embodiment, the mass ratio of lauric acid to the quaternary ammonium compound is (1-2):(1-1.5), for example, it can be 1:1, 1:1.2, 1:1.4, 1:1.5, 2:1, 2:1.2, 2:1.4, 2:1.5, etc.

[0107] As an optional embodiment, the quaternary ammonium compound includes any one or a combination of at least two of benzalkonium chloride, benzalkonium bromide, triethylammonium benzoate, cetyltrimethylammonium bromide or tetramethylammonium hydroxide.

[0108] As an optional embodiment, the second reaction liquid needs to be concentrated before adding the quaternary ammonium compound; wherein the second reaction liquid after concentration accounts for 30-50% of the volume of the second reaction liquid before concentration, for example, it can be 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, etc.

[0109] As an optional embodiment, the concentrated second reaction liquid needs to be cooled to 80-100° C. (for example, 80° C., 85° C., 90° C., 95° C., 100° C., etc.) before adding the quaternary ammonium compound.

[0110] As an optional embodiment, the temperature of the quaternization reaction is 80-120°C, for example, it can be 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, etc.

[0111] As an optional embodiment, the quaternization reaction time is 3 to 5 hours, for example, it can be 3 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours, 4 hours, 4.2 hours, 4.4 hours, 4.6 hours, 4.8 hours, 5 hours, etc.

[0112] In a third aspect, the present invention provides a use of the photovoltaic copper antioxidant in the preparation of crystalline silicon solar cells.

[0113] In a fourth aspect, the present invention provides a crystalline silicon solar cell comprising a copper grid line and a protective film on the surface of the copper grid line; wherein the protective film is formed by the photovoltaic copper antioxidant as described in the first aspect.

[0114] In a fifth aspect, the present invention provides a method for preparing a crystalline silicon solar cell as described in the fourth aspect, the preparation method comprising:

[0115] The crystalline silicon solar cell is immersed in the photovoltaic copper antioxidant as described in the first aspect, and then washed and dried to obtain the crystalline silicon solar cell; wherein both sides of the crystalline silicon solar cell have copper grid lines.

[0116] As an optional embodiment, the immersion temperature is 30-60°C, for example, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, etc.

[0117] As an optional embodiment, the immersion time is 1 to 5 minutes, for example, it can be 1 minute, 1.5 minutes, 2 minutes, 2.5 minutes, 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes, 5 minutes, etc.

[0118] As an optional embodiment, the drying temperature is 60-90°C, for example, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, etc.

[0119] As an optional embodiment, the drying time is 4 to 8 minutes, for example, 4 minutes, 4.5 minutes, 5 minutes, 5.5 minutes, 6 minutes, 6.5 minutes, 7 minutes, 7.5 minutes, 8 minutes, etc.

[0120] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples were prepared according to existing methods or directly purchased from the market.

[0121] Preparation Example 1

[0122] This preparation example provides an imidazoline quaternary ammonium salt, which is prepared by the following steps: 30 g of lauric acid and 60 mL of xylene are added to a three-necked flask, 0.6 g of aluminum oxide is added as a catalyst, and the mixture is heated at 125° C. with continuous stirring for 2 hours of dehydration reaction; the temperature of the reaction system is raised to 190° C., and 35 g of triethylenetetramine is slowly added, and a cyclization reaction is carried out at 220° C. for 3 hours; the reactants are then cooled to 110° C., 30 mL of xylene is removed by vacuum distillation, and finally cooled to 90° C., 20 g of benzalkonium chloride is added, and the mixture is reacted at 100° C. for 4 hours to obtain the imidazoline quaternary ammonium salt.

[0123] Preparation Example 2

[0124] This preparation example provides an imidazoline quaternary ammonium salt, which is prepared by the following steps: adding 20 g of lauric acid and 40 mL of xylene to a three-necked flask, adding 0.6 g of aluminum oxide as a catalyst, heating at 120° C. with continuous stirring, and performing a dehydration reaction for 3 hours; raising the temperature of the reaction system to 180° C., and slowly adding 24 g of triethylenetetramine, and performing a cyclization reaction at 210° C. for 4 hours; then cooling the reactant to 100° C., removing 40 mL of xylene by reduced pressure distillation, and finally cooling to 80° C., adding 15 g of benzalkonium bromide, and reacting at 90° C. for 5 hours to obtain the imidazoline quaternary ammonium salt.

[0125] Preparation Example 3

[0126] This preparation example provides an imidazoline quaternary ammonium salt, which is prepared by the following steps: 40 g of lauric acid and 80 mL of xylene are added to a three-necked flask, 0.6 g of aluminum oxide is added as a catalyst, and the mixture is heated at 140° C. with continuous stirring for a dehydration reaction for 1 hour; the temperature of the reaction system is raised to 200° C., 42 g of triethylenetetramine is slowly added, and a cyclization reaction is carried out at 230° C. for 2 hours; the reactant is then cooled to 120° C., 35 mL of xylene is removed by reduced pressure distillation, and finally the mixture is cooled to 100° C., 30 g of hexadecyltrimethylammonium bromide is added, and the mixture is reacted at 100° C. for 5 hours to obtain the imidazoline quaternary ammonium salt.

[0127] Comparative Preparation Example 1

[0128] This preparation example provides an imidazoline compound, which is prepared by the following steps: 30 g of lauric acid and 60 mL of xylene are added to a three-necked flask, 0.6 g of aluminum oxide is added as a catalyst, and the mixture is heated at 125° C. with continuous stirring for 2 hours of dehydration reaction; the temperature of the reaction system is raised to 190° C., and 35 g of triethylenetetramine is slowly added, and a cyclization reaction is carried out at 220° C. for 3 hours; the reactants are then cooled to 110° C., and all the solvent is removed by reduced pressure distillation to obtain the imidazoline compound.

[0129] Example 1

[0130] This embodiment provides a photovoltaic copper antioxidant, which comprises the following components by concentration:

[0131]

[0132] (a) mixing ethanol, ethylene glycol and water to obtain an alcohol aqueous solution; mixing benzimidazole and the imidazoline quaternary ammonium salt provided in Preparation Example 1 to obtain a composite corrosion inhibitor;

[0133] (b) heating the alcohol aqueous solution to 50° C., adding the composite corrosion inhibitor, and stirring at 500 rpm for 40 minutes to obtain a mixed solution;

[0134] (c) cooling the mixed solution to 25° C., adding butylated hydroxytoluene, polyoxypropylene glycol, and polyoxyethylene alkylolamide in sequence, and then stirring at 700 rpm for 40 min at 25° C. until the mixture is uniformly mixed, and adjusting the pH value to 4 with a dilute sulfuric acid solution (2 wt %), filtering to remove insoluble matter, and thus obtaining the photovoltaic copper antioxidant.

[0135] Example 2

[0136] This embodiment provides a photovoltaic copper antioxidant, which comprises the following components by concentration:

[0137]

[0138] (a) mixing ethanol, ethylene glycol and water to obtain an alcohol aqueous solution; mixing benzimidazole and the imidazoline quaternary ammonium salt provided in Preparation Example 1 to obtain a composite corrosion inhibitor;

[0139] (b) heating the alcohol aqueous solution to 60° C., adding the composite corrosion inhibitor, and stirring at 500 rpm for 45 minutes to obtain a mixed solution;

[0140] (c) cooling the mixed solution to 25° C., adding butylated hydroxytoluene, polyoxypropylene glycol, and polyoxyethylene alkylolamide in sequence, and then stirring at 700 rpm at 25° C. for 45 minutes until the mixture is uniformly mixed, and adjusting the pH value to 4 with a dilute sulfuric acid solution (2 wt %), filtering to remove insoluble matter, and thus obtaining the photovoltaic copper antioxidant.

[0141] Example 3

[0142] This embodiment provides a photovoltaic copper antioxidant, which comprises the following components by concentration:

[0143]

[0144]

[0145] (a) mixing isopropyl alcohol, glycerol and water to obtain an alcohol aqueous solution; mixing benzimidazole and the imidazoline quaternary ammonium salt provided in Preparation Example 1 to obtain a composite corrosion inhibitor;

[0146] (b) heating the alcohol aqueous solution to 60° C., adding the composite corrosion inhibitor, and stirring at 500 rpm for 45 minutes to obtain a mixed solution;

[0147] (c) cooling the mixed solution to 25° C., adding butylated hydroxytoluene, polyoxypropylene glycol, and polyoxyethylene alkylolamide in sequence, and then stirring at 700 rpm at 25° C. for 45 minutes until the mixture is uniformly mixed, and adjusting the pH value to 4 with a dilute sulfuric acid solution (2 wt %), filtering to remove insoluble matter, and thus obtaining the photovoltaic copper antioxidant.

[0148] Example 4

[0149] This embodiment provides a copper antioxidant for photovoltaic use, wherein the imidazoline quaternary ammonium salt provided in Preparation Example 1 is replaced with the imidazoline quaternary ammonium salt provided in Preparation Example 2 at an equal concentration, and the other steps are consistent with those in Example 1.

[0150] Example 5

[0151] This embodiment provides a copper antioxidant for photovoltaic use, wherein the imidazoline quaternary ammonium salt provided in Preparation Example 1 is replaced with the imidazoline quaternary ammonium salt provided in Preparation Example 3 at an equal concentration, and the other steps are consistent with those in Example 1.

[0152] Example 6

[0153] This embodiment provides a copper antioxidant for photovoltaic use. The only difference from Example 1 is that ethanol is not added, the content of ethylene glycol is increased to 120 mL / L, and the other steps are the same as Example 1.

[0154] Example 7

[0155] This embodiment provides a copper antioxidant for photovoltaic use. The only difference from Example 1 is that ethylene glycol is not added, the ethanol content is increased to 120 mL / L, and the other steps are the same as Example 1.

[0156] Example 8

[0157] This embodiment provides a copper antioxidant for photovoltaic use. The only difference from Example 1 is that polyoxypropylene glycol is not added, the content of polyoxyethylene alkyl alcohol amide is increased to 1 g / L, and the other steps are the same as Example 1.

[0158] Example 9

[0159] This embodiment provides a copper antioxidant for photovoltaic use. The only difference from Example 1 is that polyoxyethylene alkylolamide is not added, the content of polyoxypropylene glycol is increased to 1 g / L, and other steps are consistent with Example 1.

[0160] Comparative Example 1

[0161] This comparative example provides a copper antioxidant for photovoltaic use, which differs from Example 1 only in that no benzimidazole is added, the concentration of the imidazoline quaternary ammonium salt provided in Preparation Example 1 is increased to 12 g / L, and the other steps are consistent with Example 1.

[0162] Comparative Example 2

[0163] This comparative example provides a copper antioxidant for photovoltaic use, which differs from Example 1 only in that the imidazoline quaternary ammonium salt provided in Preparation Example 1 is not added, the concentration of benzimidazole is increased to 12 g / L, and the other steps are consistent with Example 1.

[0164] Comparative Example 3

[0165] This comparative example provides a copper antioxidant for photovoltaic use, which differs from Example 1 only in that the concentration of benzimidazole is adjusted to 12 g / L, the concentration of the imidazoline quaternary ammonium salt provided in Preparation Example 1 is adjusted to 2 g / L, and the other steps are consistent with Example 1.

[0166] Comparative Example 4

[0167] This comparative example provides a copper antioxidant for photovoltaic use, which differs from Example 1 only in that the concentration of benzimidazole is adjusted to 0.5 g / L, the concentration of the imidazoline quaternary ammonium salt provided in Preparation Example 1 is adjusted to 11.5 g / L, and the other steps are consistent with Example 1.

[0168] Comparative Example 5

[0169] This comparative example provides a copper antioxidant for photovoltaic use, which differs from Example 1 only in that the imidazoline quaternary ammonium salt provided in Preparation Example 1 is replaced by an imidazoline compound of equal concentration, and the other steps are consistent with Example 1.

[0170] Comparative Example 6

[0171] This comparative example provides a copper antioxidant for photovoltaic use, which differs from Example 1 only in that ethanol and ethylene glycol are not added, the content of polyoxypropylene glycol is increased to 2 g / L, and the content of polyoxyethylene alkyl alcohol amide is increased to 2 g / L. Other steps are consistent with Example 1.

[0172] Comparative Example 7

[0173] This comparative example provides a photovoltaic copper antioxidant, which differs from Example 1 only in that polyoxypropylene glycol and polyoxyethylene alkylolamide are not added, the ethanol content is increased to 100 mL / L, and the ethylene glycol content is increased to 100 mL / L. Other steps are consistent with Example 1.

[0174] Comparative Example 8

[0175] This comparative example provides a copper antioxidant for photovoltaic use, which differs from Example 1 only in that butylated hydroxytoluene is not added, the content of polyoxypropylene glycol is increased to 0.8 g / L, and the content of polyoxyethylene alkyl alcohol amide is increased to 0.7 g / L. Other steps are consistent with Example 1.

[0176] Test Example 1

[0177] Tested antioxidant samples: the photovoltaic copper antioxidants provided in Examples 1 to 9 and the photovoltaic copper antioxidants provided in Comparative Examples 1 to 8.

[0178] Preparation of test crystalline silicon solar cells: Place crystalline silicon solar cells of the same specifications in the above samples, completely immerse them, immerse them at 45°C for 2.5 minutes, take them out and wash them several times with deionized water, then blow away the water droplets on the surface with cold air, and finally dry them at 75°C for 6 minutes, and apply a protective film on the surface of the copper grid line to obtain the crystalline silicon solar cell; wherein, the crystalline silicon solar cell has copper grid lines on both sides.

[0179] Test method:

[0180] (1) Anti-oxidation performance test: The prepared crystalline silicon solar cell was subjected to an anti-oxidation performance test. The test method was to expose it to air for 30 days and observe the color of the surface of the copper grid line of the solar cell.

[0181] (2) Electrical performance test: The electrical performance of the prepared crystalline silicon solar cells was tested to compare the photoelectric conversion efficiency and series resistance before and after being placed in air for 30 days.

[0182] (3) Welding performance test: The prepared crystalline silicon solar cell was subjected to a welding test. The specific method was as follows: a tin-coated solder tape was placed on the main grid line on the surface of the crystalline silicon solar cell, assisted by a small amount of flux, the welding temperature was set to 300°C, and after standing for 2 minutes, the tensile force was tested with a tensile gauge. The tensile force at twelve PAD points was measured and the average value was taken.

[0183] The specific test results are shown in Table 1 below:

[0184] Table 1

[0185]

[0186]

[0187] As shown in Table 1, the photovoltaic copper antioxidant provided by the present invention can quickly form a well-structured, dense protective film on the surface of the copper grid, acting as a barrier layer to isolate the copper surface from air and prevent oxidation. Crystalline silicon solar cells treated with the present invention will not discolor after being exposed to air for one month. The protective film formed on the crystalline silicon solar cell by the copper antioxidant of the present invention, which is composed of a compound of benzimidazole and imidazoline quaternary ammonium salt, has good thermal stability. It can not only reduce the oxides formed on the surface of the copper grid, but also promote the formation of a new protective film during the reduction process, thereby enhancing its antioxidant capacity. In addition, it can be subjected to high-temperature welding in high-temperature environments of 300°C and above without being oxidized, and has good solderability.

[0188] From the comparison between Example 1 and Examples 6 to 7, it can be seen that the dispersant is preferably a combination of a monohydric alcohol (containing only a single hydroxyl group) and a polyol (a dihydric alcohol with a dihydroxy structure and a trihydric alcohol with a trihydroxy structure) in a specific ratio; the monohydric alcohol regulates the osmotic pressure, reduces the viscosity of the system, promotes the dispersion of antioxidant molecules to the copper surface, and improves the uniformity of coverage; and the polyol constructs a dynamic solvent structure through hydrogen bonds between hydroxyl groups, which is beneficial to improving the stabilization of the protective film.

[0189] From the comparison between Example 1 and Examples 8 to 9, it can be seen that the surfactant is preferably a combination of polyoxypropylene glycol and polyoxyethylene alkyl alcohol amide in a specific ratio. The combination of the two can effectively protect the weldability of the antioxidant under high-temperature welding and maintain the high-temperature stability of the dispersed system through a dynamic hydrogen bond network.

[0190] From the comparison of Example 1 and Comparative Examples 1 to 2, it can be seen that the benzimidazole and imidazoline quaternary ammonium salt are composed of the two, and the two cooperate with each other and have a synergistic effect, which more significantly enhances the antioxidant ability and can perform high-temperature welding without being oxidized. If any one of them is missing, even if the content of the other component is increased, it is difficult to further improve its antioxidant ability.

[0191] From the comparison of Example 1 and Comparative Examples 3 to 4, it can be seen that the benzimidazole and the imidazoline quaternary ammonium salt need to be in a certain ratio to better play a synergistic role in order to achieve the purpose of enhancing antioxidant capacity. If the concentration of either component is too high, oxidation will occur on the copper surface after being placed in the air for about 30 days.

[0192] From the comparison of Example 1 and Comparative Example 5, it can be seen that when the imidazoline quaternary ammonium salt is replaced with an imidazoline compound with a similar structure, severe oxidative discoloration will occur, indicating that the imidazoline quaternary ammonium salt provided by the present invention can fully cover the active sites of copper, directly inhibit the oxidation reaction, and enhance the chelation effect with copper through the multidentate coordination ability, which is more conducive to forming a dense chemical protective film on copper.

[0193] From the comparison between Example 1 and Comparative Examples 6 to 8, it can be seen that the photovoltaic copper antioxidant contains a dispersant, a surfactant and a stabilizer in a specific ratio. The components cooperate with each other to quickly form a structurally regular and dense protective film on the surface of the copper grid line. If any one of the components is missing, even if the content of another component is increased, it is difficult to further improve its antioxidant ability.

[0194] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A copper antioxidant for photovoltaic use, characterized in that The photovoltaic copper antioxidant comprises the following components in parts by weight: The compound corrosion inhibitor comprises benzimidazole and imidazoline quaternary ammonium salt in a mass ratio of (1-2): (5-10).

2. The photovoltaic copper antioxidant according to claim 1, characterized in that The photovoltaic copper antioxidant comprises the following components by concentration: The compound corrosion inhibitor comprises benzimidazole and imidazoline quaternary ammonium salt in a mass ratio of (1-2): (5-10).

3. The photovoltaic copper antioxidant according to claim 1 or 2, characterized in that The imidazoline quaternary ammonium salt is an imidazoline compound grafted with a quaternary ammonium compound; wherein the imidazoline compound is obtained by dehydration cyclization of lauric acid, xylene and triethylenetetramine; Preferably, the quaternary ammonium compound includes any one or a combination of at least two of benzalkonium chloride, benzalkonium bromide, triethylammonium benzoate, cetyltrimethylammonium bromide, methylbenzenedimethylammonium chloride or tetramethylammonium hydroxide.

4. The photovoltaic copper antioxidant according to claim 1, characterized in that The dispersant includes any one or a combination of at least two of C1-C5 monohydric alcohol, C2-C5 dihydric alcohol or C2-C5 trihydric alcohol; Preferably, the dispersant comprises any one of methanol, ethanol, propanol, ethylene glycol, isopropanol or glycerol, or a combination of at least two thereof; Preferably, the surfactant comprises any one or a combination of at least two of polyoxypropylene glycol, polytetramethylene glycol, polyoxyethylene alkylolamide or fatty alcohol polyoxyethylene ether; Preferably, the stabilizer includes any one of butylated hydroxytoluene, dibutylated hydroxytoluene or butylated hydroxyanisole, or a combination of at least two thereof.

5. A method for preparing a photovoltaic copper antioxidant according to any one of claims 1 to 4, characterized in that: The preparation method comprises: Dissolving the compound corrosion inhibitor in water containing a dispersant, and mixing for the first time to obtain a mixed solution; A surfactant and a stabilizer are added to the mixed solution, and mixed for a second time to obtain the photovoltaic copper antioxidant.

6. The method for preparing a photovoltaic copper antioxidant according to claim 5, wherein: The temperature of the first mixing is 40 to 80° C.; the speed of the first mixing is 300 to 600 rpm; and the time of the first mixing is 30 to 60 minutes. Preferably, the temperature of the second mixing is 20-30° C.; the rotation speed of the second mixing is 500-1000 rpm; and the time of the second mixing is 30-60 min. Preferably, after the second mixing, the method further comprises: adjusting the pH of the mixed solution to 3-5; Preferably, the reagent for adjusting the pH of the mixed solution includes sulfuric acid and / or sodium hydroxide.

7. The method for preparing a photovoltaic copper antioxidant according to claim 5, wherein: The preparation method of the imidazoline quaternary ammonium salt in the composite corrosion inhibitor comprises: Mixing lauric acid and xylene, and performing a dehydration reaction to obtain a first reaction liquid; adding triethylenetetramine to the first reaction liquid, and performing a cyclization reaction to obtain a second reaction liquid; adding a quaternary ammonium compound to the second reaction liquid, and performing a quaternization reaction to obtain the imidazoline quaternary ammonium salt; preferably, the mass ratio of the lauric acid to the xylene is 1:(1-4); Preferably, the temperature of the dehydration reaction is 100-150° C.; the time of the dehydration reaction is 1-3 hours; Preferably, the mass ratio of lauric acid to triethylenetetramine is (1-2):(1-2); Preferably, the first reaction solution is heated to 160-220° C. before adding triethylenetetramine; Preferably, the temperature of the cyclization reaction is 200-250° C.; the time of the cyclization reaction is 2-4 hours; Preferably, the dehydration reaction and cyclization reaction are carried out in the presence of a catalyst; Preferably, the catalyst comprises alumina; Preferably, the mass ratio of the lauric acid to the catalyst is 1:(0.01-0.1); Preferably, the mass ratio of the lauric acid to the quaternary ammonium compound is (1-2):(1-1.5); Preferably, the quaternary ammonium compound comprises any one or a combination of at least two of benzalkonium chloride, benzalkonium bromide, triethylammonium benzoate, cetyltrimethylammonium bromide or tetramethylammonium hydroxide; Preferably, the second reaction liquid needs to be concentrated before adding the quaternary ammonium compound; wherein the volume of the second reaction liquid after concentration accounts for 30 to 50% of the volume of the second reaction liquid before concentration; Preferably, the concentrated second reaction liquid needs to be cooled to 80-100° C. before adding the quaternary ammonium compound; Preferably, the temperature of the quaternization reaction is 80-120° C.; and the time of the quaternization reaction is 3-5 hours.

8. Use of the photovoltaic copper antioxidant according to any one of claims 1 to 4 in the preparation of crystalline silicon solar cells.

9. A crystalline silicon solar cell, characterized in that: The crystalline silicon solar cell includes a copper grid line and a protective film on the surface of the copper grid line; wherein the protective film is formed by the photovoltaic copper antioxidant according to any one of claims 1 to 4.

10. A method for preparing a crystalline silicon solar cell according to claim 9, characterized in that: The preparation method comprises: The crystalline silicon solar cell is immersed in the photovoltaic copper antioxidant, washed, and dried to obtain the crystalline silicon solar cell; wherein both sides of the crystalline silicon solar cell have copper grid lines; Preferably, the immersion temperature is 30-60°C; the immersion time is 1-5 minutes; Preferably, the drying temperature is 60-90° C.; and the drying time is 4-8 minutes.

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