High-reliability conductive silver paste for heterojunction solar cells and preparation method thereof

Abstract

The application provides a high-reliability conductive silver paste for a heterojunction solar cell and a preparation method thereof. The high-reliability conductive paste comprises the following raw materials in parts by weight: flaky silver powder 35-65 parts by weight, spherical silver powder 20-55 parts by weight, nano silver powder 0.5-5 parts by weight, thermosetting resin 1-6 parts by weight, auxiliary agent 0.1-4 parts by weight, and solvent 0.1-4 parts by weight. In the high-reliability conductive silver paste for the heterojunction solar cell, the high proportion of silver powder is filled, and the single functionality of glycidyl ether is synergistically used to balance the crosslinking degree and internal stress of the conductive paste, solve the problem of efficiency decay caused by the flux, and achieve the purposes of reducing the efficiency decay amplitude and improving the reliability.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, specifically to a high-reliability conductive silver paste for heterojunction solar cells and its preparation method. Background Technology

[0002] Currently, most HJT (heterojunction) module manufacturing processes utilize MBB (Metal-on-Branch) automated soldering. The flux introduced during this process can damage the grid lines of the HJT fine grid paste, leading to low cell conversion efficiency (CTM). Therefore, addressing the flux's erosion and damage to the fine grid and improving CTM conversion efficiency is a crucial issue that needs to be resolved in the development of conductive pastes for heterojunction solar cells. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the purpose of this invention is to provide a high-reliability conductive silver paste for heterojunction solar cells and its preparation method.

[0004] The first aspect of the present invention provides a high-reliability conductive silver paste for heterojunction solar cells, comprising the following raw materials in parts by weight: 35-65 parts by weight of flake silver powder, 20-55 parts by weight of spherical silver powder, 0.5-5 parts by weight of nano silver powder, 1-6 parts by weight of thermosetting resin, 0.1-4 parts by weight of additives, and 0.1-4 parts by weight of organic solvent.

[0005] The particle size of the flake-shaped silver powder is: D10≤1.2μm, D50≤5μm, D100≤12μm, and the tap density of the flake-shaped silver powder is 5.1~6.2g / cm³. 3 The specific surface area of ​​the flake-shaped silver powder is 0.5–0.6 m². 2 / g;

[0006] The spherical silver powder has the following particle sizes: D10≤0.2μm, D50≤0.6μm, D100≤1.5μm, and its tap density is 4.0~5.1g / cm³. 3 The specific surface area of ​​the spherical silver powder is 0.7–1.3 m². 2 / g;

[0007] The average particle size of the nano-silver powder is < 0.1 μm.

[0008] In one embodiment, the thermosetting resin includes an organic resin and a curing agent, wherein the mass ratio of the organic resin to the curing agent is 90:10 to 50:50.

[0009] In one embodiment, the organic resin is at least one of epoxy resin, acrylic resin, polyurethane resin and its modified derivatives; the curing agent is at least one of amine compound, imidazole compound, acid anhydride compound and isocyanate compound.

[0010] In one embodiment, the amine curing agent is at least one of dicyandiamide, boron trifluoride ethylamine complex, and boron trichloride ethylamine complex.

[0011] In one embodiment, the imidazole curing agent is at least one of 2-ethylimidazole, 2-methylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-methylbenzimidazole, 2-phenylimidazole, and heptadecaalkylimidazole.

[0012] In one embodiment, the mixture further includes 0.1-2 parts by weight of an epoxy reactive diluent, wherein the epoxy reactive diluent is a monofunctional glycidyl ether. The structural formula of the monofunctional glycidyl ether is as follows:

[0013]

[0014] Wherein, R is benzyl, C12-C14 alkyl, butyl or other carbon chain.

[0015] In one embodiment, the monofunctional glycidyl ether is at least one of benzyl glycidyl ether, C12-C14 alkyl glycidyl ether, and butyl glycidyl ether.

[0016] In one embodiment, the additive includes at least one of a thixotropic agent, a leveling agent, a dispersant, and a coupling agent;

[0017] The thixotropic agent is at least one of fumed silica, organobentonite, hydrogenated castor oil, and polyamide wax.

[0018] The leveling agent is at least one of acrylic, modified polysiloxane, and fluorocarbon compounds;

[0019] The dispersant is at least one of sulfonate, ammonium salt, carboxylate, polyester, and polyurethane;

[0020] The silane coupling agent is at least one of aminosilane coupling agents, epoxy-terminated silane coupling agents, titanate coupling agents, and aluminate coupling agents.

[0021] In one embodiment, the organic solvent is at least one selected from diethylene glycol butyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether acetate, ethyl acetate, butyl acetate, naphtha, propylene glycol methyl ether acetate, dimethyl succinate, dimethyl glutarate, dimethyl adipate, tributyl citrate, dibutyl phthalate, butyl benzyl phthalate, butyl stearate, oleic acid, butyl oleate, and terpineol.

[0022] A second aspect of this invention provides a method for preparing a high-reliability conductive silver paste for heterojunction solar cells, comprising the following steps:

[0023] Weigh out the following amounts of the formula: flake silver powder, spherical silver powder, nano silver powder, epoxy reactive diluent, thermosetting resin, additives, and organic solvent;

[0024] Epoxy reactive diluent, thermosetting resin, additives, and organic solvents are all added to the reaction vessel and stirred and mixed. Then, nano silver powder, spherical silver powder, and flake silver powder are added in sequence and stirred and mixed to obtain a uniformly mixed slurry.

[0025] The uniformly mixed slurry was ground using a three-roll mill, with the grinding gap adjusted from large to small, ranging from 120μm to 20μm.

[0026] Filtering through a 300-mesh sieve yields a highly reliable conductive silver paste for use in heterojunction solar cells.

[0027] Compared with the prior art, the present invention has the following beneficial effects: In the high-reliability conductive silver paste for heterojunction solar cells provided by the embodiments of the present invention, the crosslinking degree and internal stress of the conductive paste are balanced by the filling of a high proportion of silver powder and the synergistic effect of monofunctional glycidyl ether, thereby solving the problem of efficiency decay caused by flux and achieving the purpose of reducing the efficiency decay rate and improving reliability. Detailed Implementation

[0028] Currently, most HJT module manufacturing processes employ MBB automated soldering technology. The flux introduced during this process can damage the grid lines of the HJT fine grid paste, resulting in low CTM conversion efficiency. Therefore, how to solve the problem of low CTM conversion efficiency caused by flux erosion and damage to the fine grid is an urgent issue to be addressed.

[0029] In this invention, the applicant discovered that after the epoxy resin in the conductive paste is cured, the originally freely moving molecular chains are solidified into a three-dimensional network structure, resulting in volume shrinkage. This volume shrinkage allows the silver powder particles to be packed more tightly, increasing conductivity and improving photoelectric conversion efficiency. However, it also brings other side reactions, generating internal stress, which causes microscopic delamination between the silver paste and the silicon wafer pyramid structure. If it comes into contact with flux, small flux molecules will penetrate into the gaps and remain permanently, forming a non-conductive film, leading to increased contact resistance and reduced conversion efficiency.

[0030] Therefore, the applicant of this invention proposes a high-reliability conductive silver paste for heterojunction solar cells to solve the problem of flux erosion and damage to the fine grid, thereby improving the conversion efficiency of CTM.

[0031] To address the issue of flux eroding and damaging the fine grid, it is essential to strike a balance between the crosslinking degree and internal stress in the conductive paste.

[0032] The high-reliability conductive silver paste for heterojunction solar cells provided in this invention comprises the following raw materials in parts by weight: 35-65 parts by weight of flake silver powder, 20-55 parts by weight of spherical silver powder, 0.5-5 parts by weight of nano silver powder, 0.1-2 parts by weight of epoxy reactive diluent, 1-6 parts by weight of thermosetting resin, 0.1-4 parts by weight of additives, and 0.1-4 parts by weight of solvent. By filling a high proportion of small spherical powder (D50 < 0.5 μm), the gaps between large silver powder particles and the gaps between the silver powder and the pyramid structure of the silicon wafer can be effectively filled, making it difficult for flux to penetrate. In addition, the addition of monofunctional glycidyl ether can reduce the internal stress of the curing system, so that the cured silver paste body will not undergo microscopic delamination from the pyramid structure, further preventing flux penetration.

[0033] The high-reliability conductive silver paste for heterojunction solar cells provided by this invention balances the crosslinking degree and internal stress of the conductive paste by filling with a high proportion of silver powder and the synergistic effect of monofunctional glycidyl ether, thereby solving the problem of efficiency degradation caused by flux and achieving the goal of reducing the rate of efficiency degradation and improving reliability.

[0034] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0035] Example 1

[0036] This embodiment provides a high-reliability conductive silver paste for heterojunction solar cells. By weight, the conductive silver paste comprises: 38 parts of flake silver powder (D50 = 4 μm, tap density = 5.5 g / cm³). 3 ), 54 parts of spherical silver powder (D50 = 0.4 μm, tap density = 4.5 g / cm³). 3 The composition includes: 1 part nano silver powder, 2.0 parts epoxy resin, 2.0 parts blocked isocyanate, 0.2 parts boron trifluoride ethylamine complex, 0.2 parts 2-ethyl-4-methylimidazole, 0.6 parts epoxy-terminated silane coupling agent, and 2.0 parts diethylene glycol butyl ether acetate.

[0037] The high-reliability conductive silver paste for heterojunction solar cells in this embodiment is prepared through the following steps:

[0038] First, pour the epoxy resin, blocked isocyanate, boron trifluoride ethylamine complex, 0.2 parts of 2-ethyl-4-methylimidazole, epoxy-terminated silane coupling agent, diethylene glycol butyl ether acetate and other liquid components into the reactor, control the temperature at 25℃, stir at 50r / min, and stir for 30 minutes.

[0039] Then, nano silver powder, spherical silver powder and flake silver powder are added in sequence. The temperature is controlled at 25℃, the stirring speed is 50r / min, and the mixture is stirred for 90 minutes to obtain a uniform slurry.

[0040] Then, the slurry is ground using a three-roll mill, with the grinding gap adjusted from large to small, from 120μm to 20μm.

[0041] Finally, the mixture is filtered through a 300-mesh sieve to obtain a uniformly dispersed conductive silver paste with a viscosity of 200–300 Pa·s.

[0042] Example 2

[0043] This embodiment provides a high-reliability conductive silver paste for heterojunction solar cells. By weight, the conductive silver paste comprises: 35 parts of flake silver powder (D50 = 4 μm, tap density = 5.5 g / cm³). 3 55 parts of spherical silver powder (D50 = 0.4 μm, tap density = 4.5 g / cm³) 3 The composition includes: 3 parts nano silver powder, 2.0 parts epoxy resin, 2.0 parts blocked isocyanate, 0.2 parts boron trifluoride ethylamine complex, 0.2 parts 2-ethyl-4-methylimidazole, 0.6 parts epoxy-terminated silane coupling agent, and 2.0 parts diethylene glycol butyl ether acetate.

[0044] The high-reliability conductive silver paste for heterojunction solar cells in this embodiment is prepared through the following steps:

[0045] First, pour the liquid components such as epoxy resin, blocked isocyanate, boron trifluoride ethylamine complex, 2-ethyl-4-methylimidazolium, epoxy-terminated silane coupling agent, and diethylene glycol butyl ether acetate into the reactor, control the temperature at 25°C, stir at 50 r / min, and stir for 30 minutes.

[0046] Then, nano silver powder, spherical silver powder and flake silver powder are added in sequence. The temperature is controlled at 25℃, the stirring speed is 50r / min, and the mixture is stirred for 90 minutes to obtain a uniform slurry.

[0047] Then, the slurry is ground using a three-roll mill, with the grinding gap adjusted from large to small, from 120μm to 20μm.

[0048] Finally, the mixture is filtered through a 300-mesh sieve to obtain a uniformly dispersed conductive silver paste with a viscosity of 200–300 Pa·s.

[0049] Example 3

[0050] This embodiment provides a high-reliability conductive silver paste for heterojunction solar cells. By weight, the conductive silver paste comprises: 38 parts of flake silver powder (D50 = 4 μm, tap density = 5.5 g / cm³). 3 50 parts of spherical silver powder (D50 = 0.4 μm, tap density = 4.5 g / cm³) 3 The composition includes: 5 parts nano silver powder, 2.0 parts epoxy resin, 2.0 parts blocked isocyanate, 0.2 parts boron trifluoride ethylamine complex, 0.2 parts 2-ethyl-4-methylimidazole, 0.3 parts epoxy-terminated silane coupling agent, and 2.3 parts diethylene glycol butyl ether acetate.

[0051] The high-reliability conductive silver paste for heterojunction solar cells in this embodiment is prepared through the following steps:

[0052] First, pour the epoxy resin, blocked isocyanate, boron trifluoride ethylamine complex, 0.2 parts of 2-ethyl-4-methylimidazole, epoxy-terminated silane coupling agent, diethylene glycol butyl ether acetate and other liquid components into the reactor, control the temperature at 25℃, stir at 50r / min, and stir for 30 minutes.

[0053] Then, nano silver powder, spherical silver powder and flake silver powder are added in sequence. The temperature is controlled at 25℃, the stirring speed is 50r / min, and the mixture is stirred for 90 minutes to obtain a uniform slurry.

[0054] Then, the slurry is ground using a three-roll mill, with the grinding gap adjusted from large to small, from 120μm to 20μm.

[0055] Finally, the mixture is filtered through a 300-mesh sieve to obtain a uniformly dispersed conductive silver paste with a viscosity of 200–300 Pa·s.

[0056] Example 4

[0057] This embodiment provides a high-reliability conductive silver paste for heterojunction solar cells. By weight, the conductive silver paste comprises: 35 parts of flake silver powder (D50 = 4 μm, tap density = 5.5 g / cm³). 3 55 parts of spherical silver powder (D50 = 0.4 μm, tap density = 4.5 g / cm³) 3 The composition includes: 3 parts nano silver powder, 1.6 parts epoxy resin, 2.0 parts blocked isocyanate, 0.6 parts benzyl glycidyl ether, 0.2 parts boron trifluoride ethylamine complex, 0.2 parts 2-ethyl-4-methylimidazole, 0.3 parts epoxy-terminated silane coupling agent, and 2.1 parts diethylene glycol butyl ether acetate.

[0058] The high-reliability conductive silver paste for heterojunction solar cells in this embodiment is prepared through the following steps:

[0059] First, pour the liquid components such as epoxy resin, blocked isocyanate, benzyl glycidyl ether, boron trifluoride ethylamine complex, 2-ethyl-4-methylimidazolium, epoxy-terminated silane coupling agent, and diethylene glycol butyl ether acetate into the reactor, control the temperature at 25°C, stir at 50 r / min, and stir for 30 minutes.

[0060] Then, nano silver powder, spherical silver powder and flake silver powder are added in sequence. The temperature is controlled at 25℃, the stirring speed is 50r / min, and the mixture is stirred for 90 minutes to obtain a uniform slurry.

[0061] Then, the slurry is ground using a three-roll mill, with the grinding gap adjusted from large to small, from 120μm to 20μm.

[0062] Finally, the mixture is filtered through a 300-mesh sieve to obtain a uniformly dispersed conductive silver paste with a viscosity of 200–300 Pa·s.

[0063] Example 5

[0064] This embodiment provides a high-reliability conductive silver paste for heterojunction solar cells. By weight, the conductive silver paste comprises: 35 parts of flake silver powder (D50 = 4 μm, tap density = 5.5 g / cm³). 3 55 parts of spherical silver powder (D50 = 0.4 μm, tap density = 4.5 g / cm³) 3 The composition includes: 3 parts nano silver powder, 1.6 parts epoxy resin, 2.0 parts blocked isocyanate, 0.6 parts C12-C14 alkyl glycidyl ether, 0.2 parts boron trifluoride ethylamine complex, 0.2 parts 2-ethyl-4-methylimidazole, 0.3 parts epoxy-terminated silane coupling agent, and 2.1 parts diethylene glycol butyl ether acetate.

[0065] The high-reliability conductive silver paste for heterojunction solar cells in this embodiment is prepared through the following steps:

[0066] First, pour the liquid components such as epoxy resin, blocked isocyanate, C12-C14 alkyl glycidyl ether, boron trifluoride ethylamine complex, 2-ethyl-4-methylimidazolium, epoxy-terminated silane coupling agent, and diethylene glycol butyl ether acetate into the reactor, control the temperature at 25°C, stir at 50 r / min, and stir for 30 minutes.

[0067] Then, nano silver powder, spherical silver powder and flake silver powder are added in sequence. The temperature is controlled at 25℃, the stirring speed is 50r / min, and the mixture is stirred for 90 minutes to obtain a uniform slurry.

[0068] Then, the slurry is ground using a three-roll mill, with the grinding gap adjusted from large to small, from 120μm to 20μm.

[0069] Finally, the mixture is filtered through a 300-mesh sieve to obtain a uniformly dispersed conductive silver paste with a viscosity of 200–300 Pa·s.

[0070] Example 6

[0071] This embodiment provides a high-reliability conductive silver paste for heterojunction solar cells. By weight, the conductive silver paste comprises: 35 parts of flake silver powder (D50 = 4 μm, tap density = 5.5 g / cm³). 3 55 parts of spherical silver powder (D50 = 0.4 μm, tap density = 4.5 g / cm³) 3 The composition includes: 3 parts nano silver powder, 1.6 parts epoxy resin, 2.0 parts blocked isocyanate, 0.6 parts butyl glycidyl ether, 0.2 parts boron trichloride ethylamine complex, 0.2 parts 2-ethyl-4-methylimidazole, 0.3 parts epoxy-terminated silane coupling agent, and 2.1 parts diethylene glycol butyl ether acetate.

[0072] The high-reliability conductive silver paste for heterojunction solar cells in this embodiment is prepared through the following steps:

[0073] First, pour the liquid components such as epoxy resin, blocked isocyanate, butyl glycidyl ether, boron trichloride ethylamine complex, 2-ethyl-4-methylimidazol, epoxy-terminated silane coupling agent, and diethylene glycol butyl ether acetate into the reactor, control the temperature at 25℃, stir at 50r / min, and stir for 30 minutes.

[0074] Then, nano silver powder, spherical silver powder and flake silver powder are added in sequence. The temperature is controlled at 25℃, the stirring speed is 50r / min, and the mixture is stirred for 90 minutes to obtain a uniform slurry.

[0075] Then, the slurry is ground using a three-roll mill, with the grinding gap adjusted from large to small, from 120μm to 20μm.

[0076] Finally, the mixture is filtered through a 300-mesh sieve to obtain a uniformly dispersed conductive silver paste with a viscosity of 200–300 Pa·s.

[0077] Comparative Example 1

[0078] This comparative example provides a conductive silver paste, which, by weight, comprises: 55 parts of flake silver powder (D50 = 5 μm, tap density = 5.6 g / cm3), 38 parts of spherical silver powder (D50 = 0.8 μm, tap density = 4.8 g / cm3), 2.0 parts of epoxy resin, 2.0 parts of blocked isocyanate, 0.4 parts of 2-ethyl-4-methylimidazole, 0.6 parts of epoxy-terminated silane coupling agent, and 2.0 parts of diethylene glycol butyl ether acetate.

[0079] The conductive silver paste in this embodiment is prepared through the following steps:

[0080] First, pour the liquid components such as epoxy resin, blocked isocyanate, 2-ethyl-4-methylimidazolium, epoxy-terminated silane coupling agent, and diethylene glycol butyl ether acetate into the reactor, control the temperature at 25℃, stir at 50r / min, and stir for 30 minutes.

[0081] Then add spherical silver powder and flake silver powder in sequence, control the temperature at 25℃, stir at 50r / min, and stir for 90 minutes to obtain a uniform slurry;

[0082] Then, the slurry is ground using a three-roll mill, with the grinding gap adjusted from large to small, from 120μm to 20μm.

[0083] Finally, the mixture is filtered through a 300-mesh sieve to obtain a uniformly dispersed conductive silver paste with a viscosity of 200–300 Pa·s.

[0084] Test case

[0085] In this experimental example, the performance of the high-reliability conductive silver pastes for heterojunction solar cells prepared in Examples 1-6 and the conductive silver pastes prepared in the comparative examples were tested. The results are shown in Table 1.

[0086] All electrical performance (conversion efficiency) values ​​below were measured using an IV tester. Test conditions were 25℃, M1.5 spectrum, and 1.000 kW / m². Reference standard: GB / T 6495.1-1996 Photovoltaic Devices - Part 1: Measurement of Photovoltaic Current and Voltage Characteristics.

[0087] The above results compare the efficiency degradation data of the solar cells before and after flux treatment (using a flux pen to apply flux to the silver grid lines of the solar cells and drying at 200℃). Table 1 shows that adding nano-silver powder or spherical silver powder, as well as adding monofunctional glycidyl ether, significantly improves the degree of efficiency degradation.

[0088] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A high-reliability conductive silver paste for heterojunction solar cells, characterized in that, The raw materials include the following parts by weight: 35-65 parts by weight of flake silver powder, 20-55 parts by weight of spherical silver powder, 0.5-5 parts by weight of nano silver powder, 1-6 parts by weight of thermosetting resin, 0.1-4 parts by weight of additives, 0.1-4 parts by weight of organic solvent, and 0.1-2 parts by weight of epoxy reactive diluent. The particle size of the flake-shaped silver powder is: D10≤1.2μm, D50≤5μm, D100≤12μm, and the tap density of the flake-shaped silver powder is 5.1~6.2g / cm³. 3 The specific surface area of ​​the flake-shaped silver powder is 0.5–0.6 m². 2 / g; The spherical silver powder has the following particle sizes: D10≤0.2μm, D50≤0.6μm, D100≤1.5μm, and its tap density is 4.0~5.1g / cm³. 3 The specific surface area of ​​the spherical silver powder is 0.7–1.3 m². 2 / g; The average particle size of the nano-silver powder is < 0.1 μm; The epoxy reactive diluent is at least one of benzyl glycidyl ether and C12-C14 alkyl glycidyl ether.

2. The high-reliability conductive silver paste for heterojunction solar cells according to claim 1, characterized in that, The thermosetting resin includes an organic resin and a curing agent, wherein the mass ratio of the organic resin to the curing agent is 90:10 to 50:

50.

3. The high-reliability conductive silver paste for heterojunction solar cells according to claim 2, characterized in that, The organic resin is at least one of epoxy resin, acrylic resin, polyurethane resin and their modified derivatives; the curing agent is at least one of amine compounds, imidazole compounds, acid anhydride compounds and isocyanate compounds.

4. The high-reliability conductive silver paste for heterojunction solar cells according to claim 3, characterized in that, The amine curing agent is at least one of dicyandiamide, boron trifluoride ethylamine complex, and boron trichloride ethylamine complex.

5. The high-reliability conductive silver paste for heterojunction solar cells according to claim 3, characterized in that, The imidazole curing agent is at least one of 2-ethylimidazole, 2-methylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-methylbenzimidazole, 2-phenylimidazole, and heptadecaalkylimidazole.

6. The high-reliability conductive silver paste for heterojunction solar cells according to claim 1, characterized in that, The additives include at least one of thixotropic agents, leveling agents, dispersants, and coupling agents; The thixotropic agent is at least one of fumed silica, organobentonite, hydrogenated castor oil, and polyamide wax. The leveling agent is at least one of acrylic, modified polysiloxane, and fluorocarbon compounds; The dispersant is at least one of sulfonate, ammonium salt, carboxylate, polyester, and polyurethane; The coupling agent is at least one of aminosilane coupling agents, epoxy-terminated silane coupling agents, titanate coupling agents, and aluminate coupling agents.

7. The high-reliability conductive silver paste for heterojunction solar cells according to claim 1, characterized in that, The organic solvent is at least one of diethylene glycol butyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether acetate, ethyl acetate, butyl acetate, naphtha, propylene glycol methyl ether acetate, dimethyl succinate, dimethyl glutarate, dimethyl adipate, tributyl citrate, dibutyl phthalate, butyl benzyl phthalate, butyl stearate, oleic acid, butyl oleate, and terpineol.

8. A method for preparing a high-reliability conductive silver paste for heterojunction solar cells according to any one of claims 1-7, characterized in that, Includes the following steps: Weigh out the following amounts of the formula: flake silver powder, spherical silver powder, nano silver powder, epoxy reactive diluent, thermosetting resin, additives, and organic solvent; Epoxy reactive diluent, thermosetting resin, additives, and organic solvents are all added to the reaction vessel and stirred and mixed. Then, nano silver powder, spherical silver powder, and flake silver powder are added in sequence and stirred and mixed to obtain a uniformly mixed slurry. The uniformly mixed slurry was ground using a three-roll mill, with the grinding gap adjusted from large to small, ranging from 120μm to 20μm. Filtering through a 300-mesh sieve yields a highly reliable conductive silver paste for use in heterojunction solar cells.

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