TOPCon back fine grid photovoltaic silver paste with high photoelectric conversion efficiency and preparation method thereof

Abstract

The invention relates to the technical field of photovoltaic materials, in particular to high-photoelectric-conversion-efficiency TOPCon back fine grid photovoltaic silver paste and a preparation method thereof.The high-photoelectric-conversion-efficiency TOPCon back fine grid photovoltaic silver paste is at least prepared from, by weight, 80-91 parts of silver powder, 7-16 parts of organic carriers, 1.3-4.5 parts of glass powder, 0.3-3 parts of organic additives and 0-5 parts of solvent, and the silver powder comprises single-crystal silver powder and polycrystal silver powder; by optimizing selection and matching of the silver powder, the resin and other raw materials in the system, the provided silver paste has excellent printing performance, adhesive force and photoelectric conversion efficiency at the same time, and the actual application requirements are better met.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic materials, and in particular to a high-photoelectric conversion efficiency TOPCon back-side fine-grid photovoltaic silver paste and a preparation method thereof. Background Art

[0002] TOPCon cells, with their ultra-thin SiO2 (1-2nm) backside passivation contact structure and doped polysilicon (Poly-Si), have become a highly efficient technology in the photovoltaic field. This structure requires the backside silver paste to penetrate the passivation layer while forming a low-damage ohmic contact with the Poly-Si and maintaining the grid line aspect ratio. It is reported that the global TOPCon silver paste market will exceed 50 billion yuan in 2025, with backside silver paste accounting for over 60%.

[0003] Silver paste is the core electrode material in photovoltaic cells. Silicon wafers generate current under light, and silver paste is used to collect and conduct this current. Silver powder is the largest component of silver paste, and the choice of silver powder directly affects the bulk resistance and contact resistance of the electrode material. The back of the TOPCon cell needs to be screen-printed so that the silver paste can be accurately printed on the cell surface to form conductive grid lines. Currently, acrylic acid is usually used as the main resin in the TOPCon back silver paste to provide adhesion. For example, a Chinese patent (authorization publication number CN104681123B) discloses a solar cell back silver paste and its preparation method, a solar cell and its preparation method. The silver paste obtained mainly has a lower sintering temperature and welding performance by optimizing the silver powder particle size selection. However, the use of acrylic resin systems in back silver paste currently faces two problems: First, the bonding strength with the hydroxyl groups of the silicon wafer is weak, and the addition amount often needs to be increased to ensure sufficient adhesion; second, the thixotropy of acrylic resin is high. Excessive acrylic resin will reduce the silver paste's meshing during the printing process, which can easily cause fine grid breakage and affect the line shape. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a TOPCon back-side fine-grid photovoltaic silver paste with high photoelectric conversion efficiency. By optimizing the selection and combination of silver powder, resin and other raw materials in the system, the provided silver paste has excellent printability, adhesion and photoelectric conversion efficiency, which can better meet the actual application needs.

[0005] On the one hand, the present invention provides a high-photoelectric conversion efficiency TOPCon back-side fine-grid photovoltaic silver paste, the preparation raw materials of which include at least 80 to 91 parts of silver powder, 7 to 16 parts of organic carrier, 1.3-4.5 parts of glass powder, 0.3 to 3 parts of organic additives, and 0 to 5 parts of solvent, and the silver powder includes single crystal silver powder and polycrystalline silver powder.

[0006] In one embodiment, the raw materials for preparing the high photoelectric conversion efficiency TOPCon back-side fine grid photovoltaic silver paste include at least 85 to 90 parts of silver powder, 8 to 10 parts of organic carrier, 1.5-2 parts of glass powder, 0.5 to 1 part of organic additives, and 0 to 2 parts of solvent, calculated by weight.

[0007] In one embodiment, the model of the single crystal silver powder is selected from at least one of Yinke MG series, Yinke YK series, Jianbang 152 series, Smet G series or Smet SH series.

[0008] In one embodiment, the model of the single crystal silver powder is selected from at least one of Yinke YK-6, Yinke YK-7, Yinke YK-9, Jianbang 152-20, Jianbang 152-209, Jianbang 152-10n, Smet G560 or Smet G595.

[0009] In one embodiment, the polycrystalline silver powder is of a type selected from at least one of Yinke TP series, Yinke EC series, Smet FG series, Smet SK series, Yinrui YRP series, and Yinrui YRS series.

[0010] In one embodiment, the model of the polycrystalline silver powder is selected from at least one of Yinrui YRP-377, Yinrui YRP-377F, Yinrui YRS-S700A, Yinrui YRS-S700-2, Yinke EC-3T or Yinke EC-3L4.

[0011] In one embodiment, the mass ratio of the single crystal silver powder to the polycrystalline silver powder is (15-40): (45-80).

[0012] In one embodiment, the mass ratio of the single crystal silver powder to the polycrystalline silver powder is (18-34):(51-72).

[0013] The present invention comprises single crystal silver powder and polycrystalline silver powder in the silver paste system, and controls the mass ratio of the single crystal silver powder to the polycrystalline silver powder, thereby reducing the viscosity of the silver paste and improving the mesh passability of the silver paste, thereby effectively improving the printability of the paste. At the same time, the anchoring effect between the silver paste and the organic carrier is enhanced, which reduces sedimentation and stratification, is conducive to forming a dense silver layer structure, and enhances conductivity.

[0014] In one embodiment, the raw materials for preparing the organic vehicle include at least: epoxy resin, ethyl cellulose, phenoxy resin, organic solvent, curing agent, and curing agent accelerator.

[0015] In one embodiment, the raw materials for preparing the organic carrier include at least 12-25 parts of epoxy resin, 2-8 parts of ethyl cellulose, 1-10 parts of phenoxy resin, 0-15 parts of phenolic resin, 0-20 parts of polyvinyl butyral resin, 40-80 parts of organic solvent, 5-20 parts of curing agent, and 1-8 parts of curing agent accelerator, calculated by weight.

[0016] In one embodiment, the raw materials for preparing the organic carrier include at least 16-20 parts of epoxy resin, 4-5.2 parts of ethyl cellulose, 2-7.5 parts of phenoxy resin, 0-13.9 parts of phenolic resin, 0-17.5 parts of polyvinyl butyral resin, 50-70 parts of organic solvent, 6.1-15 parts of curing agent, and 3.5-5.8 parts of curing agent accelerator, calculated by weight.

[0017] In one embodiment, the polyvinyl butyral resin is selected from at least one of Kuraray 30H, Kuraray 30HH, Kuraray 60H, Kuraray 20H, Eastman Butvar B-76, Solutia B-98, and Sekisui BL-2H.

[0018] In one embodiment, the polyvinyl butyral resin is of the type Kuraray 30HH.

[0019] In one embodiment, the epoxy resin is selected from the group consisting of Bluestar Chemical CYD-014, Nanya NPEF-170, Kuodu Chemical KER-8280, Huntsman At least one of GY 250, Baling Petrochemical E-44 or Japan Mitsubishi JER4250.

[0020] In one embodiment, the epoxy resin is selected from one of Bluestar Chemical CYD-014, Kukto Chemical KER-8280, or Mitsubishi JER4250.

[0021] In one embodiment, the ethyl cellulose is of a type selected from at least one of Ashland 250HHR, Ashland PLUS330, Eastman CAB-381-20, Dow Std4, Dow Std10, and Dow Std45.

[0022] In one embodiment, the ethyl cellulose is of a type selected from Ashland 250HHR, Eastman CAB-381-20, or Dow Std4.

[0023] In one embodiment, the phenoxy resin is selected from at least one of Union Carbide PKHP-80, Union Carbide PKHP-200, Union Carbide PKHH, Huntsman Chemical PKHH, or Huntsman Chemical PKHB.

[0024] In one embodiment, the phenoxy resin is produced by Union Carbide PKHP-80 from the United States or Huntsman Chemical PKHH from the United States.

[0025] In one embodiment, the phenolic resin is of a type selected from at least one of Sumitomo Bakelite PR-12603, Sumitomo Bakelite PR-12602, and Sumitomo Bakelite PR-12604.

[0026] In one embodiment, the phenolic resin is of the type Sumitomo Bakelite PR-12603 from Japan.

[0027] In one embodiment, the organic solvent is selected from at least one of dimethyl phthalate, dimethyl terephthalate, triethylene glycol monobutyl ether, tripropylene glycol monobutyl ether, diethylene glycol butyl ether, diethylene glycol butyl ether acetate, alcohol ester-12, alcohol ester-16, butyl carbiphenol, butyl carbiphenol acetate, terpineol, benzyl benzoate or ethylene glycol phenyl ether.

[0028] In one embodiment, the organic solvent includes diethylene glycol butyl ether, benzyl benzoate, diethylene glycol butyl ether acetate and triethylene glycol monobutyl ether, and the mass ratio of diethylene glycol butyl ether, benzyl benzoate, diethylene glycol butyl ether acetate and triethylene glycol monobutyl ether is (1-2.5): (1.5-4): (0.5-0.8): (0.4-1.8).

[0029] In one embodiment, the mass ratio of diethylene glycol butyl ether, benzyl benzoate, diethylene glycol butyl ether acetate and triethylene glycol monobutyl ether is (14-20.8): (21.2-35): (5.3-7.8): (5.2-14).

[0030] In one embodiment, the curing agent is selected from at least one of phthalic anhydride, polyether polyol, dicyandiamide, adipic acid dihydrazide, boron trifluoride complex, ethylenediamine, m-phenylenediamine, isocyanate, dimethylimidazole or dimethylpyrazole.

[0031] In one embodiment, the curing agent is isocyanate or dimethylimidazole.

[0032] In one embodiment, the type of the isocyanate is selected from Wanhua PM200, Wanhua HT100, BASF M20S or Covestro Imprafix 2794XP.

[0033] In one embodiment, the type of dimethylimidazole is selected from one of Fufei Chemical PA04292, Shandong Zhongyi 65260 or Japan Shikoku Chemical 2E4MZ.

[0034] In one embodiment, the curing accelerator is selected from at least one of tetrabutylammonium bromide, 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30), dimethylaminophenol (DMP-10), benzyldimethylamine or N-p-chlorophenyl-N,N'-dimethylurea.

[0035] In one embodiment, the curing accelerator is selected from one of tetrabutylammonium bromide, DMP-30 or benzyldimethylamine.

[0036] In one embodiment, the method for preparing the organic carrier comprises at least the following steps: adding the raw materials into a container and stirring at 60-100° C. for 30-180 minutes.

[0037] Furthermore, by optimizing the resin blend in the system, including epoxy resin, ethyl cellulose, phenoxy resin, and / or phenolic resin, polyvinyl butyral resin, the silver paste achieves multiple properties, including meshability, leveling, fine linearity, and adhesion. In particular, the uncured epoxy resin in the system can form a pre-adhesion layer on the substrate surface through hydrogen bonding, reducing printing offset. Furthermore, by introducing a curing agent and curing accelerator, the silver paste rapidly cures to form a three-dimensional cross-linked network, achieving excellent adhesion to the back of the silicon wafer. This dense cured layer also reduces curing shrinkage, helping to maintain linearity and ensure printability.

[0038] In one embodiment, the organic additive is selected from at least one of fumed silica, hydrogenated castor oil, oleic acid, polyhydroxystearic acid, polyamide wax, polyvinyl alcohol, titanate coupling agent, siloxane coupling agent, polyurethane, silicone oil, polysiloxane, polyvinyl alcohol or polyvinyl chloride.

[0039] In one embodiment, the organic additives include polyamide wax, silicone oil, and polyvinyl alcohol.

[0040] In one embodiment, the mass ratio of the polyamide wax, silicone oil and polyvinyl alcohol is (0.3-0.5):0.2:(0-0.3).

[0041] In one embodiment, the polyamide wax is of the type of Hermes P200X or Disparlon 6900-20X.

[0042] In one embodiment, the silicone oil is of the type Qiangli Chemical 201 or Dow Chemical PMX-200.

[0043] In one embodiment, the polyvinyl alcohol is of the type Sinopec 2099.

[0044] In one embodiment, the glass powder comprises at least the following components, in parts by weight: 1-5 parts of Na2O, 1-5 parts of Al2O3, 4-8 parts of TiO2, 25-35 parts of SiO2, 8-12 parts of ZnO, 1-3 parts of WO3, 30-40 parts of PbO, and 10-15 parts of Bi2O3.

[0045] In one embodiment, the glass powder includes the following components, in parts by weight: 3 parts Na2O, 3 parts Al2O3, 6 parts TiO2, 28 parts SiO2, 10 parts ZnO, 2 parts WO3, 35 parts PbO, and 13 parts Bi2O3.

[0046] In one embodiment, the preparation method of the glass powder includes the following steps: mixing the components by weight, melting them into a uniform glass liquid at 900-1100° C., quenching them into glass sheets through water, and obtaining glass powder through ball milling and air flow pulverization.

[0047] In one embodiment, the glass powder has a particle size D50 of 1.0-1.5 μm.

[0048] In one embodiment, the solvent includes at least diethylene glycol butyl ether acetate.

[0049] On the other hand, the present invention provides a method for preparing TOPCon back-side fine-grid photovoltaic silver paste with high photoelectric conversion efficiency, which comprises at least the following steps: adding silver powder, organic carrier, glass powder, organic additive, and solvent into a blender by weight, stirring for 0.5 to 2 hours at a stirring speed of 300 to 750 rpm, and rolling 3 to 6 times through a three-roll grinder.

[0050] The silver paste provided by the present invention overcomes the problems of weak bonding between traditional silver paste systems and silicon wafers and poor mesh penetration of the silver paste during the printing process, which leads to printing defects such as fine grid breakage. The preparation method is simple and easy to achieve large-scale industrial promotion and application.

[0051] Beneficial effects

[0052] 1. The present invention provides a TOPCon back-side fine-grid photovoltaic silver paste with high photoelectric conversion efficiency. By optimizing the selection and combination of silver powder, resin and other raw materials in the system, the provided silver paste has excellent printability, adhesion and photoelectric conversion efficiency, which can better meet the needs of actual applications.

[0053] 2. The present invention reduces the viscosity of the silver paste and improves the mesh-passing property of the silver paste by controlling the mass ratio of the single crystal silver powder and the polycrystalline silver powder in the silver paste system, thereby effectively improving the printability of the paste. At the same time, the anchoring effect between the silver paste and the organic carrier is enhanced, which reduces sedimentation and stratification, is conducive to forming a dense silver layer structure, and enhances conductivity.

[0054] 3. The present invention optimizes the compounding of resins in the system, including epoxy resin, ethyl cellulose, phenoxy resin and / or phenolic resin, polyvinyl butyral resin, so that the provided silver paste takes into account multiple properties such as the paste's mesh passability, leveling, fine linearity, adhesion, etc., especially the epoxy resin in the system can be adsorbed on the surface of the substrate through hydrogen bonds to form a pre-attachment layer before curing, thereby reducing printing deviation.

[0055] 4. The present invention introduces a curing agent and a curing accelerator, so that the provided silver paste can be quickly cured in a short time to form a three-dimensional cross-linked network, thereby achieving excellent adhesion on the back of the silicon wafer. This dense cured layer can also reduce the curing shrinkage rate, which is beneficial to maintaining the linear shape and ensuring printability.

[0056] 5. The silver paste provided by the present invention overcomes the problems of weak bonding between traditional silver paste systems and silicon wafers and poor mesh penetration of silver paste during the printing process, which leads to printing defects such as fine grid breakage. The preparation method is simple and easy to achieve large-scale industrial promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is a 3D test image of the silver paste provided in Example 1 during printing test.

[0058] Figure 2 This is a 3D test image of the silver paste provided in Example 2 during printing test.

[0059] Figure 3 This is a 3D test image of the silver paste provided in Example 3 during printing test.

[0060] Figure 4 This is a 3D test image of the silver paste provided in Comparative Example 1 during printing test.

[0061] Figure 5 This is a 3D test image of the silver paste provided in Comparative Example 2 during printing test.

[0062] Figure 6 This is a 3D test image of the silver paste provided in Comparative Example 3 during printing test. DETAILED DESCRIPTION

[0063] Examples 1-3, Comparative Examples 1-3

[0064] On the one hand, Examples 1-3 and Comparative Examples 1-3 of the present invention provide a TOPCon back-side fine-grid photovoltaic silver paste with high photoelectric conversion efficiency. The formula is shown in Table 1 in parts by weight.

[0065] Table 1

[0066]

[0067]

[0068] In Table 1: the formula of organic carriers 1-4 is shown in Table 2; the glass powder includes the following components, by weight: 3 parts of Na2O, 3 parts of Al2O3, 6 parts of TiO2, 28 parts of SiO2, 10 parts of ZnO, 2 parts of WO3, 35 parts of PbO, and 13 parts of Bi2O3; the preparation method of the glass powder includes the following steps: mixing the components, by weight, melting them at 1000°C into a uniform glass liquid, quenching them into glass sheets through water, and obtaining glass powder by ball milling and air flow pulverization; the particle size D50 of the glass powder is 1-1.3 μm.

[0069] Table 2

[0070]

[0071]

[0072] The preparation method of the organic carrier 1 includes the following steps: stirring epoxy resin, ethyl cellulose, phenoxy resin, and polyvinyl butyral resin at 40° C. and 500 rpm for 20 minutes, adjusting the temperature to 80° C. and continuing to stir at 2000 rpm for 120 minutes to prepare an organic resin solution, adding a curing agent and a curing agent accelerator to the organic resin solution, and stirring at 25° C. and 300 rpm for 10 minutes to obtain the organic carrier 1.

[0073] The preparation method of the organic carrier 2 includes the following steps: stirring epoxy resin, ethyl cellulose, phenoxy resin, and phenolic resin at 70°C and 600 rpm for 10 minutes, adjusting the temperature to 100°C and stirring at 1000 rpm for 60 minutes to prepare an organic resin solution, adding a curing agent and a curing agent accelerator to the organic resin solution, and stirring at 25°C and 300 rpm for 10 minutes to obtain the organic carrier 2.

[0074] The preparation method of the organic carrier 3 includes the following steps: stirring epoxy resin, ethyl cellulose, phenoxy resin, and polyvinyl butyral resin at 55°C and 300 rpm for 30 minutes, adjusting the temperature to 85°C and stirring at 1000 rpm for 90 minutes to prepare an organic resin solution, adding a curing agent and a curing agent accelerator to the organic resin solution, and stirring at 25°C and 300 rpm for 10 minutes to obtain the organic carrier 3.

[0075] The preparation method of the organic carrier 4 includes the following steps: epoxy resin, ethyl cellulose, phenoxy resin, and polyvinyl butyral resin are stirred at 40°C and 500 rpm for 20 minutes, the temperature is adjusted to 80°C, and the stirring speed is 2000 rpm for 120 minutes to obtain the organic carrier 4.

[0076] On the other hand, Examples 1-3 and Comparative Examples 1-3 of the present invention provide a method for preparing TOPCon back-side fine-grid photovoltaic silver paste with high photoelectric conversion efficiency, comprising the following steps: adding silver powder, organic carrier, glass powder, organic additive, and solvent to a blender by weight, stirring for 1 hour at a stirring speed of 300 rpm, and rolling through a three-roll grinder 5 times.

[0077] Performance Testing

[0078] 1. The high photoelectric conversion efficiency TOPCon back fine grid photovoltaic silver paste provided in the embodiment and the comparative example was respectively printed on the back of the 182mm×182mm TOPCon cell by screen printing, and the silver paste was uniformly printed on the front. The cell was sintered at a peak temperature of 700°C in a sintering furnace and light was injected. The cell was then passed through a LECO device for laser-assisted sintering to obtain a cell. The photoelectric conversion efficiency (Eta), open circuit voltage (Uoc), short circuit current (Isc), fill factor (FF), series resistance (Rs), and parallel resistance (Rsh) of the cell were tested using a Halm IV tester. The test results are shown in Table 3 (50 cells were used for each embodiment and comparative example, and the corresponding efficiency data were expressed as the average value).

[0079] 2. The printing effect of the silver paste prepared in the examples and comparative examples was evaluated. The evaluation contents included: printing aspect ratio (printing line height / printing line width), wear resistance, line type and broken gate situation; the broken gate situation of the battery cell was detected by EL tester and the line type was checked by 3D microscope; the battery cell was subjected to a tearing test using 3M tape to compare the wear resistance. The specific method was: 3M tape was adhered to the surface of the battery cell, compacted 3 times with a roller, quickly torn, and the shedding situation was compared. If there was no shedding, the wear resistance was recorded as "good", and if there was shedding, the wear resistance was recorded as "average"; the results are shown in Table 3 and Figure 1-6 .

[0080] Table 3

[0081]

[0082]

[0083] By analyzing Table 3, it can be seen that the cells prepared using the silver paste provided in Examples 1-3 have excellent photoelectric conversion efficiency, wear resistance and printing effect compared to the cells prepared using the silver paste provided in Comparative Examples 1-3.

[0084] analyze Figure 1-6 It can be seen that the silver paste obtained in Examples 1-3 has narrow and straight lines after printing, uniform line width, good smoothness and flatness; while the line type of Comparative Example 1 is wide, with an obvious gourd knot phenomenon in the middle section, and silver paste is scattered around the line to a certain extent; the line type of Comparative Example 2 is wide, with silver paste scattered around the line to a certain extent; the line type of Comparative Example 3 is wide, with an obvious gourd knot phenomenon in the middle section.

Claims

1. A high photoelectric conversion efficiency TOPCon backside fine grid photovoltaic silver paste, characterized in that: The raw materials for its preparation include at least 80-91 parts of silver powder, 7-16 parts of organic carrier, 1.3-4.5 parts of glass powder, 0.3-3 parts of organic additive, and 0-5 parts of solvent by weight. The silver powder includes single crystal silver powder and polycrystalline silver powder.

2. The high photoelectric conversion efficiency TOPCon back-side fine grid photovoltaic silver paste according to claim 1, characterized in that: The raw materials for preparing the organic carrier at least include: epoxy resin, ethyl cellulose, phenoxy resin, organic solvent, curing agent, and curing agent accelerator.

3. The high photoelectric conversion efficiency TOPCon backside fine grid photovoltaic silver paste according to claim 1, characterized in that: The mass ratio of the single crystal silver powder to the polycrystalline silver powder is (15-40):(45-80).

4. The high photoelectric conversion efficiency TOPCon backside fine grid photovoltaic silver paste according to claim 2, characterized in that: The raw materials for preparing the organic carrier include at least 12-25 parts of epoxy resin, 2-8 parts of ethyl cellulose, 1-10 parts of phenoxy resin, 0-15 parts of phenolic resin, 0-20 parts of polyvinyl butyral resin, 40-80 parts of organic solvent, 5-20 parts of curing agent, and 1-8 parts of curing agent accelerator, in parts by weight.

5. The high photoelectric conversion efficiency TOPCon back-grid photovoltaic silver paste according to claim 4, wherein the organic solvent is selected from at least one of dimethyl phthalate, dimethyl terephthalate, triethylene glycol monobutyl ether, tripropylene glycol monobutyl ether, diethylene glycol butyl ether, diethylene glycol butyl ether acetate, alcohol ester-12, alcohol ester-16, butyl carbicarbonate, butyl carbicarbonate acetate, terpineol, benzyl benzoate or ethylene glycol phenyl ether.

6. The high photoelectric conversion efficiency TOPCon backside fine grid photovoltaic silver paste according to claim 4, characterized in that: The curing agent is selected from at least one of phthalic anhydride, polyether polyol, dicyandiamide, adipic acid dihydrazide, boron trifluoride complex, ethylenediamine, m-phenylenediamine, isocyanate, dimethylimidazole or dimethylpyrazole.

7. The high photoelectric conversion efficiency TOPCon backside fine grid photovoltaic silver paste according to claim 4, characterized in that: The curing accelerator is selected from at least one of tetrabutylammonium bromide, 2,4,6-tris(dimethylaminomethyl)phenol, dimethylaminophenol, benzyldimethylamine or N-p-chlorophenyl-N,N'-dimethylurea.

8. The high photoelectric conversion efficiency TOPCon backside fine grid photovoltaic silver paste according to claim 1, characterized in that: The organic additive is selected from at least one of fumed silica, hydrogenated castor oil, oleic acid, polyhydroxystearic acid, polyamide wax, polyvinyl alcohol, titanate coupling agent, siloxane coupling agent, polyurethane, silicone oil, polysiloxane, polyvinyl alcohol or polyvinyl chloride.

9. The high photoelectric conversion efficiency TOPCon backside fine grid photovoltaic silver paste according to claim 1, characterized in that: In parts by weight, the glass powder comprises at least the following components: 1-5 parts of Na2O, 1-5 parts of Al2O3, 4-8 parts of TiO2, 25-35 parts of SiO2, 8-12 parts of ZnO, 1-3 parts of WO3, 30-40 parts of PbO, and 10-15 parts of Bi2O3.

10. A method for preparing a high photoelectric conversion efficiency TOPCon backside fine grid photovoltaic silver paste according to any one of claims 1 to 9, characterized in that: The method comprises at least the following steps: adding silver powder, organic carrier, glass powder, organic additive and solvent into a stirrer according to weight, stirring for 0.5 to 2 hours at a stirring speed of 300 to 750 rpm, and rolling the mixture through a three-roll mill for 3 to 6 times.

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