CN114203336B - HJT solar cell main fine grid general silver paste containing graphene and preparation method thereof - Google Patents

Abstract

The present invention provides a universal silver paste for main and fine grids of HJT solar cells containing graphene, which is prepared from the following components by mass percentage: 15-19% of micron-grade flaky silver powder, 68-72% of submicron-grade spherical silver powder, 3-7% of nano-grade spherical silver powder, 0.12-0.16% of filler, 2-4% of resin, 0.1-0.2% of modifier, 3-5% of solvent, 0.1-0.2% of coupling agent, 0.1-0.2% of dispersant, 0.1-0.2% of curing agent, 0.1-0.2% of accelerator, and 0.08-0.16% of wetting agent. The present invention can not only realize one-step printing of main and fine grids, but also reduce the overall resistivity, improve adhesion, and make the dispersibility, thixotropy and weather resistance of the slurry better.

Description

A universal silver paste for main fine grid of HJT solar cell containing graphene and its preparation method

Technical Field

The invention relates to the technical field of solar cell metallization, and in particular to a universal silver paste for main and fine grids of HJT solar cells containing graphene and a preparation method thereof.

Background technique

With the continuous advancement of photovoltaic cell technology, the trend of iteration from P-type to N-type will begin in 2021, moving towards a higher efficiency level. N-type technology routes represented by TOPCon (Tunnel Oxide Passivating Contacts) tunnel oxide passivation contact cells and HJT (Heterojunction with Intrinsic Thinfilm) heterojunction cells have made breakthroughs one after another, and the industrialization process is expected to accelerate. Compared with TOPCon, HJT has better contact resistance and passivation effects, is more suitable for thin film, has higher photoelectric conversion efficiency, and can meet the requirements of the next generation of stacked cells. At present, the electrodes of HJT batteries mainly adopt the screen printing process, using low-temperature curing conductive silver paste. Among them, the low-temperature silver paste used for fine grid printing needs to have lower body resistance and contact resistance, high adhesion, aspect ratio and excellent weather resistance, as well as excellent printability; while the low-temperature silver paste used for main grid printing needs to have good conductivity, printability and excellent tensile strength.

Defects and shortcomings of the existing technology:

1. The main and fine grids are printed in steps, which reduces production efficiency. The two main and fine grid slurries are used for printing, which has matching problems. It is difficult to identify the cause of abnormalities in the production line.

2. If the main grid requires excellent pulling force, the proportion of resin needs to be appropriately increased, which will increase the resistivity;

3. The size, specific surface area, coupling agent and dispersant of the nano-sphere powder used in the fine grid are not suitable, resulting in poor contact resistance and adhesion, uneven dispersion, high viscosity of the slurry, and reduced curing reaction activity of the resin;

4. In order to ensure the printing aspect ratio, the thixotropic agent used cannot volatilize during low-temperature curing, and remains in the electrode as impurities, increasing the resistivity;

5. The epoxy resin and curing agent used are not suitable, resulting in water mist and salt mist corroding the contact position between the gate line and the silicon wafer surface over time, significantly increasing the contact resistance, reducing the adhesion, and the weather resistance of the gate line is poor.

Summary of the invention

To solve the above problems, the present invention discloses a universal silver paste for main and fine grids of HJT solar cells containing graphene and a preparation method thereof, which can not only realize one-step printing of main and fine grids, but also reduce the overall resistivity and improve adhesion, thereby making the slurry have better dispersibility, thixotropy and weather resistance.

The specific plan is as follows:

A universal silver paste for main and fine grids of HJT solar cells containing graphene, characterized in that it is prepared from the following components in percentage by mass: 15-19% micron-grade flaky silver powder, 68-72% submicron-grade spherical silver powder, 3-7% nano-grade spherical silver powder, 0.12-0.16% filler, 2-4% resin, 0.1-0.2% modifier, 3-5% solvent, 0.1-0.2% coupling agent, 0.1-0.2% dispersant, 0.1-0.2% curing agent, 0.1-0.2% accelerator, and 0.08-0.16% wetting agent.

As a further improvement of the present invention, the micron-level flaky silver powder has a D50 of 1-5 μm, the submicron-level spherical silver powder has a D50 of 0.2-0.5 μm, and the nano-level spherical silver powder has a D50 of 10-50 nm.

As a further improvement of the present invention, the filler is one or both of hydroxylated graphene and carboxylated graphene, wherein the sheet diameter of the carboxylated graphene is 0.5-5 μm and the thickness is 0.8-1.2 nm.

As a further improvement of the present invention, the resin is one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, carboxyl terminated polyester resin, and carboxyl acrylic resin.

As a further improvement of the present invention, the modifier is one or more of acrylic acid, gallic acid, methyl dehydroabietic acid, dehydroabietic acid, oleic acid, and 3,3',5,5'-tetramethylbiphenol.

As a further improvement of the present invention, the solvent is one or more of butyl carbitol, butyl carbitol acetate, terpineol, alcohol ester dodecanol, tributyl citrate, and diethylene glycol butyl ether.

As a further improvement of the present invention, the coupling agent is one or more of the silane coupling agents A151, A171, and A172.

As a further improvement of the present invention, the dispersant is one or more of octylphenyl polyoxyethylene ether, N-methyl pyrrolidone, and polyethylene glycol oleate.

As a further improvement of the present invention, the curing agent is one or more of triglycidyl isocyanurate, β-hydroxyalkylamide, acrylic acid-modified hydroxyalkylamide, and oleic acid-modified hydroxyalkylamide.

As a further improvement of the present invention, the accelerator is one or more of carboxylic acid ester, methylhydrazine, and aminoimine.

As a further improvement of the present invention, the wetting agent is one or more of 2.4.7.9-tetramethyl-5-decyne-4.7-diol, oleamidopropyl dimethylamine, trimethylbutene glycol, oleyl alcohol polyoxyethylene ether, and fluorine surfactant FC-4430.

A method for preparing a universal silver paste for a main fine grid of a HJT solar cell containing graphene, characterized in that the specific steps are as follows:

Step (1) using a thermostatic stirrer, slowly pouring the nano-scale spherical silver powder into the solvent along the wall of the beaker, setting the speed to 600 rpm, the temperature to 25° C., and the stirring time to 1 hour, and then using a centrifuge to mix, the speed to 1200 rpm, the temperature to 25° C., the time to mix for 30 minutes, and mixing evenly to obtain a first mixture;

Step (2) uses a thermostatic stirrer with a speed set at 600 rpm and a temperature set at 60°C, adds resin, and introduces N2 gas into the bottom of the beaker. First, add the wetting agent, dispersant, and coupling agent to the beaker in sequence. After stirring evenly, slowly add the filler, stir for 1 hour, and then cool to room temperature to obtain a second mixture.

Step (3) at room temperature, the second mixture, the modifier, the curing agent, and the accelerator are slowly added to the first mixture in sequence using a thermostatic agitator, the speed is set to 600 rpm, and the stirring time is 1 hour. Then, a centrifuge is used at a speed of 1200 rpm, a temperature of 25° C., and a time of 30 minutes to mix evenly to obtain a third mixture;

Step (4) Finally, add micron-sized flaky silver powder and submicron-sized spherical silver powder to the third mixture, use a three-roll mill to mix, set the speed to 750 rpm, in the first step, the initial roll gap is 60 μm and the final roll gap is 30 μm, and mix three times; in the second step, the initial roll gap is 30 μm and the final roll gap is 15 μm, and mix three times; in the third step, the initial roll gap is 15 μm and the final roll gap is 7 μm, and mix five times; in the fourth step, the initial roll gap is 10 μm and the final roll gap is 4 μm, and mix six times to ensure uniform dispersion and obtain a finished silver paste.

The beneficial effects of the present invention are:

1. Compared with ordinary graphene, hydroxylated or carboxylated graphene has greater affinity for polar molecules and is easier to disperse in a carrier based on epoxy resin;

2. With graphene as the core, composite point-shaped spherical nano silver powder and flaky silver powder, add appropriate dispersant, and adopt appropriate dispersion method, take advantage of the excellent electrical conductivity, thermal conductivity and flexible flake structure of graphene, can form efficient point, line and surface contact on the entire epoxy resin system, form a three-dimensional conductive network, can reduce body resistance, and provide greater pulling force;

3. Graphene has a large diameter-to-thickness ratio. A small amount of addition can improve the thixotropy of the silver paste and obtain a better aspect ratio and conversion efficiency.

4. From the perspective of thermal properties, graphene is the material with the highest thermal conductivity known so far. Adding it as a filler can improve the heat resistance of epoxy resin. After the epoxy resin is cured, the cross-linking becomes denser, and the graphene shrinks more compactly, and has better resistance to cold and hot shocks.

5. Due to the small size effect and two-dimensional sheet structure of graphene, the defects in the epoxy resin coating can be improved, so that it can form a dense insulation layer in the coating, thereby improving the water-proof effect, reducing the self-corrosion current density, and improving the acid resistance, salt resistance and other corrosion resistance and weather resistance;

6. Choose appropriate dispersants, such as octylphenyl polyoxyethylene ether, N-methylpyrrolidone, and polyethylene glycol oleate, to improve dispersion uniformity;

7. Select appropriate silane coupling agents A151, A171, A172 to improve the bonding and compatibility between graphene and epoxy resin;

8. Use bubbling and stirring together for better dispersibility.

Detailed ways

The present invention will be further explained below in conjunction with specific implementation modes. It should be understood that the following specific implementation modes are only used to illustrate the present invention and are not used to limit the scope of the present invention.

Example 1

A universal silver paste for main fine grid of HJT solar cell containing graphene is prepared from the following components according to mass percentage:

Micron-sized flake silver powder (D50: 1μm): 15%

Submicron spherical silver powder (D50: 0.2μm): 72%

Nano-scale spherical silver powder (D50: 10nm): 5%

Filler: Hydroxylated graphene (sheet diameter 0.5~5μm, thickness 0.8~1.2nm): 0.14%

Resin: Bisphenol A epoxy resin: 2%

Modifier: Acrylic acid: 0.1%

Solvent: Butyl Carbitol: 5%

Coupling agent: Silane coupling agent A151: 0.1%

Dispersant: Octylphenyl polyoxyethylene ether: 0.1%

Curing agent: triglycidyl isocyanurate: 0.2%

Accelerator: Carboxylate: 0.2%

Wetting agent: 2.4.7.9-Tetramethyl-5-decyne-4.7-diol: 0.16%

A method for preparing a universal silver paste for main fine grid of HJT solar cells containing graphene, the specific steps are as follows:

Step (1) using a thermostatic stirrer, slowly pour the nano-scale spherical silver powder into the solvent along the wall of the beaker, set the speed to 600 rpm, the temperature to 25°C, and the stirring time to 1 hour. Then use a centrifuge to mix, the speed is 1200 rpm, the temperature is 25°C, and the time is 30 minutes. Mix evenly to obtain a first mixture;

Step (2) uses a thermostatic stirrer with a speed set at 600 rpm and a temperature set at 60°C, adds resin, and introduces N2 gas into the bottom of the beaker. First, add the wetting agent, dispersant, and coupling agent to the beaker in sequence. After stirring evenly, slowly add the filler, stir for 1 hour, and then cool to room temperature to obtain a second mixture.

Step (3) at room temperature, the second mixture, the modifier, the curing agent, and the accelerator are slowly added to the first mixture in sequence using a thermostatic agitator, the speed is set to 600 rpm, and the stirring time is 1 hour. Then, a centrifuge is used at a speed of 1200 rpm, a temperature of 25° C., and a time of 30 minutes to mix evenly to obtain a third mixture;

Step (4) Finally, add micron-sized flaky silver powder and submicron-sized spherical silver powder to the third mixture, and mix them using a three-roll mill, setting the speed to 750 rpm. In the first step, the initial roll gap is 60 μm and the final roll gap is 30 μm, and the mixture is mixed three times; in the second step, the initial roll gap is 30 μm and the final roll gap is 15 μm, and the mixture is mixed three times; in the third step, the initial roll gap is 15 μm and the final roll gap is 7 μm, and the mixture is mixed five times; in the fourth step, the initial roll gap is 10 μm and the final roll gap is 4 μm, and the mixture is mixed six times. The mixture is evenly dispersed to obtain a finished silver paste.

Example 2

A universal silver paste for main fine grid of HJT solar cell containing graphene is prepared from the following components according to mass percentage:

Micron-sized flake silver powder (D50: 5μm): 16%

Submicron spherical silver powder (D50: 0.5μm): 69%

Nano-scale spherical silver powder (D50: 50nm): 7%

Filler: Carboxylated graphene (sheet diameter 0.5~5μm, thickness 0.8~1.2nm): 0.16%

Resin: Bisphenol F epoxy resin: 2.5%

Modifier: Gallic acid: 0.12%

Solvent: Butyl Carbitol Acetate: 4.5%

Coupling agent: Silane coupling agent A171: 0.12%

Dispersant: N-methylpyrrolidone: 0.12%

Curing agent: β-hydroxyalkylamide: 0.17%

Accelerator: Hydrazine: 0.17%

Wetting agent: Oleamidopropyl dimethylamine: 0.14%

A method for preparing a universal silver paste for main fine grid of HJT solar cells containing graphene, the specific steps are as follows:

Step (1) using a thermostatic stirrer, slowly pour the nano-scale spherical silver powder into the solvent along the wall of the beaker, set the speed to 600 rpm, the temperature to 25°C, and the stirring time to 1 hour. Then use a centrifuge to mix, the speed is 1200 rpm, the temperature is 25°C, and the time is 30 minutes. Mix evenly to obtain a first mixture;

Step (2) uses a thermostatic stirrer with a speed set at 600 rpm and a temperature set at 60°C, adds resin, and introduces N2 gas into the bottom of the beaker. First, add the wetting agent, dispersant, and coupling agent to the beaker in sequence. After stirring evenly, slowly add the filler, stir for 1 hour, and then cool to room temperature to obtain a second mixture.

Step (3) at room temperature, the second mixture, the modifier, the curing agent, and the accelerator are slowly added to the first mixture in sequence using a thermostatic agitator, the speed is set to 600 rpm, and the stirring time is 1 hour. Then, a centrifuge is used at a speed of 1200 rpm, a temperature of 25° C., and a time of 30 minutes to mix evenly to obtain a third mixture;

Step (4) Finally, add micron-sized flaky silver powder and submicron-sized spherical silver powder to the third mixture, and mix them using a three-roll mill, setting the speed to 750 rpm. In the first step, the initial roll gap is 60 μm and the final roll gap is 30 μm, and the mixing is performed three times; in the second step, the initial roll gap is 30 μm and the final roll gap is 15 μm, and the mixing is performed three times; in the third step, the initial roll gap is 15 μm and the final roll gap is 7 μm, and the mixing is performed five times; in the fourth step, the initial roll gap is 10 μm and the final roll gap is 4 μm, and the mixing is performed six times. The dispersion is uniform to obtain a finished silver paste.

Example 3

A universal silver paste for main fine grid of HJT solar cell containing graphene is prepared from the following components according to mass percentage:

Micron-sized flake silver powder (D50: 3μm): 17%

Submicron spherical silver powder (D50: 0.3μm): 71%

Nano-spherical silver powder (D50: 30nm): 4%

Filler: One or two of carboxylated graphene (sheet diameter 0.5~5μm, thickness 0.8~1.2nm): 0.13%

Resin: Carboxyl terminated polyester resin: 3%

Modifier: Methyl dehydroabietate: 0.15%

Solvent: terpineol: 4%

Coupling agent: one or more of silane coupling agent A172: 0.15%

Dispersant: Polyethylene glycol oleate: 0.15%

Curing agent: acrylic acid modified hydroxyalkyl amide: 0.15%

Accelerator: aminoimide: 0.15%

Wetting agent: trimethylbutylene glycol: 0.12%

A method for preparing a universal silver paste for main fine grid of HJT solar cells containing graphene, the specific steps are as follows:

Step (1) using a thermostatic stirrer, slowly pour the nano-scale spherical silver powder into the solvent along the wall of the beaker, set the speed to 600 rpm, the temperature to 25°C, and the stirring time to 1 hour. Then use a centrifuge to mix, the speed is 1200 rpm, the temperature is 25°C, and the time is 30 minutes. Mix evenly to obtain a first mixture;

Step (2) uses a thermostatic stirrer with a speed set at 600 rpm and a temperature set at 60°C, adds resin, and introduces N2 gas into the bottom of the beaker. First, add the wetting agent, dispersant, and coupling agent to the beaker in sequence. After stirring evenly, slowly add the filler, stir for 1 hour, and then cool to room temperature to obtain a second mixture.

Step (3) at room temperature, the second mixture, the modifier, the curing agent, and the accelerator are slowly added to the first mixture in sequence using a thermostatic agitator, the speed is set to 600 rpm, and the stirring time is 1 hour. Then, a centrifuge is used at a speed of 1200 rpm, a temperature of 25° C., and a time of 30 minutes to mix evenly to obtain a third mixture;

Step (4) Finally, add micron-sized flaky silver powder and submicron-sized spherical silver powder to the third mixture, and mix them using a three-roll mill, setting the speed to 750 rpm. In the first step, the initial roll gap is 60 μm and the final roll gap is 30 μm, and the mixture is mixed three times; in the second step, the initial roll gap is 30 μm and the final roll gap is 15 μm, and the mixture is mixed three times; in the third step, the initial roll gap is 15 μm and the final roll gap is 7 μm, and the mixture is mixed five times; in the fourth step, the initial roll gap is 10 μm and the final roll gap is 4 μm, and the mixture is mixed six times. The mixture is evenly dispersed to obtain a finished silver paste.

Example 4

A universal silver paste for main fine grid of HJT solar cell containing graphene is prepared from the following components according to mass percentage:

Micron-sized flake silver powder (D50: 2μm): 18%

Submicron spherical silver powder (D50: 0.3μm): 68%

Nano-scale spherical silver powder (D50: 20nm): 6%

Filler: Hydroxylated graphene (sheet diameter 0.5~5μm, thickness 0.8~1.2nm): 0.15%

Resin: Carboxylic acrylic resin: 3.5%

Modifier: Dehydroabietic acid: 0.17%

Solvent: Alcohol ester twelve: 3.5%

Coupling agent: silane coupling agent A151: 0.08%, A171: 0.09%

Dispersant: Octylphenyl polyoxyethylene ether 0.08%, N-methylpyrrolidone 0.09%

Curing agent: Oleic acid modified hydroxyalkylamide: 0.12%

Accelerator: Carboxylate 0.06%, Methylhydrazine 0.06%

Wetting agent: 0.1% oleyl alcohol polyoxyethylene ether

A method for preparing a universal silver paste for main fine grid of HJT solar cells containing graphene, the specific steps are as follows:

Step (1) using a thermostatic stirrer, slowly pour the nano-scale spherical silver powder into the solvent along the wall of the beaker, set the speed to 600 rpm, the temperature to 25°C, and the stirring time to 1 hour. Then use a centrifuge to mix, the speed is 1200 rpm, the temperature is 25°C, and the time is 30 minutes. Mix evenly to obtain a first mixture;

Step (2) uses a thermostatic stirrer with a speed set at 600 rpm and a temperature set at 60°C, adds resin, and introduces N2 gas into the bottom of the beaker. First, add the wetting agent, dispersant, and coupling agent to the beaker in sequence. After stirring evenly, slowly add the filler, stir for 1 hour, and then cool to room temperature to obtain a second mixture.

Step (3) at room temperature, the second mixture, the modifier, the curing agent, and the accelerator are slowly added to the first mixture in sequence using a thermostatic agitator, the speed is set to 600 rpm, and the stirring time is 1 hour. Then, a centrifuge is used at a speed of 1200 rpm, a temperature of 25° C., and a time of 30 minutes to mix evenly to obtain a third mixture;

Step (4) Finally, add micron-sized flaky silver powder and submicron-sized spherical silver powder to the third mixture, and mix them using a three-roll mill, setting the speed to 750 rpm. In the first step, the initial roll gap is 60 μm and the final roll gap is 30 μm, and the mixture is mixed three times; in the second step, the initial roll gap is 30 μm and the final roll gap is 15 μm, and the mixture is mixed three times; in the third step, the initial roll gap is 15 μm and the final roll gap is 7 μm, and the mixture is mixed five times; in the fourth step, the initial roll gap is 10 μm and the final roll gap is 4 μm, and the mixture is mixed six times. The mixture is evenly dispersed to obtain a finished silver paste.

Example 5

A universal silver paste for main fine grid of HJT solar cell containing graphene is prepared from the following components according to mass percentage:

Micron-sized flake silver powder (D50: 4μm): 19%

Submicron spherical silver powder (D50: 0.4μm): 70%

Nano-spherical silver powder (D50: 40nm): 3%

Filler: Hydroxylated graphene 0.06%, carboxylated graphene (sheet diameter 0.5~5μm, thickness 0.8~1.2nm): 0.06%

Resin: bisphenol F epoxy resin 2%, carboxyl acrylic resin 2%

Modifier: Oleic acid 0.2%

Solvent: Tributyl citrate 3%

Coupling agent: Silane coupling agent A171: 0.1%, A172: 0.1%

Dispersant: N-methylpyrrolidone 0.1%, polyethylene glycol oleate 0.1%

Curing agent: β-hydroxyalkylamide 0.05%, acrylic acid modified hydroxyalkylamide 0.05%

Accelerator: methyl hydrazine 0.05%, amino imine 0.05%

Wetting agent: Fluorine surfactant FC-4430: 0.08%

A method for preparing a universal silver paste for main fine grid of HJT solar cells containing graphene, the specific steps are as follows:

Step (1) using a thermostatic stirrer, slowly pour the nano-scale spherical silver powder into the solvent along the wall of the beaker, set the speed to 600 rpm, the temperature to 25°C, and the stirring time to 1 hour. Then use a centrifuge to mix, the speed is 1200 rpm, the temperature is 25°C, and the time is 30 minutes. Mix evenly to obtain a first mixture;

Step (2) uses a thermostatic stirrer with a speed set at 600 rpm and a temperature set at 60°C, adds resin, and introduces N2 gas into the bottom of the beaker. First, add the wetting agent, dispersant, and coupling agent to the beaker in sequence. After stirring evenly, slowly add the filler, stir for 1 hour, and then cool to room temperature to obtain a second mixture.

Step (3) at room temperature, the second mixture, the modifier, the curing agent, and the accelerator are slowly added to the first mixture in sequence using a thermostatic agitator, the speed is set to 600 rpm, and the stirring time is 1 hour. Then, a centrifuge is used at a speed of 1200 rpm, a temperature of 25° C., and a time of 30 minutes to mix evenly to obtain a third mixture;

Step (4) Finally, add micron-sized flaky silver powder and submicron-sized spherical silver powder to the third mixture, and mix them using a three-roll mill, setting the speed to 750 rpm. In the first step, the initial roll gap is 60 μm and the final roll gap is 30 μm, and the mixture is mixed three times; in the second step, the initial roll gap is 30 μm and the final roll gap is 15 μm, and the mixture is mixed three times; in the third step, the initial roll gap is 15 μm and the final roll gap is 7 μm, and the mixture is mixed five times; in the fourth step, the initial roll gap is 10 μm and the final roll gap is 4 μm, and the mixture is mixed six times. The mixture is evenly dispersed to obtain a finished silver paste.

compare results

1. Comparison of tensile strength and weather resistance, see the table below:

As shown in the above table, the tensile forces of the embodiments are greater than those of the comparative examples, and the contact resistance changes in the weather resistance test are also less than those of the comparative examples.

2. Slurry viscosity comparison

As shown in the above table, the viscosity of the embodiments is lower than that of the comparative examples, and the thixotropic value and aspect ratio are larger, and the printing performance is better.

3. Battery performance comparison

The performance of a HJT solar cell containing graphene prepared in the above embodiment is shown in the following table:

From the above table, it can be concluded that the conductivity, printability, conversion efficiency and other properties of the universal silver paste for the main fine grid of HJT solar cells containing graphene in the above embodiment are excellent, and can meet the requirements of the silk-screen grid of mainstream HJT solar cells in the market.

The above embodiments contain graphene-containing HJT solar cell main fine grid universal silver paste, submicron-level, nano-level spherical silver powder and graphene, which can form a smaller resistivity, higher conversion efficiency and tension, and better weather resistance.

The present invention adopts functionalized graphene, namely hydroxylated or carboxylated graphene, to increase its compatibility in epoxy resin; selects suitable dispersants, such as octylphenyl polyoxyethylene ether, N-methyl pyrrolidone and polyethylene glycol oleate, to improve dispersion uniformity; selects suitable silane coupling agents A151, A171 and A172 to improve bonding and compatibility between graphene and epoxy resin; and adopts bubbling and stirring in combination to achieve better dispersibility.

The technical means disclosed in the scheme of the present invention are not limited to the technical means disclosed in the above-mentioned implementation mode, but also include technical schemes composed of any combination of the above-mentioned technical features. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also regarded as the protection scope of the present invention.

Claims (1)

1. The common silver paste containing the main fine grid of the graphene HJT solar cell is characterized in that: the composite material is prepared from the following components in percentage by mass: 15-19% of micron-sized flake silver powder, 68-72% of submicron-sized spherical silver powder, 3-7% of nano-sized spherical silver powder, 0.12-0.16% of filler, 2-4% of resin, 0.1-0.2% of modifier, 3-5% of solvent, 0.1-0.2% of coupling agent, 0.1-0.2% of dispersing agent, 0.1-0.2% of curing agent, 0.1-0.2% of accelerator and 0.08-0.16% of wetting agent; the micron-sized flake silver powder is D50:1-5 μm, the submicron spherical silver powder is D50:0.2-0.5 mu m, wherein the nano-scale spherical silver powder is D50:10-50nm; the filler is one or two of hydroxylated graphene and carboxylated graphene, wherein the sheet diameter of the carboxylated graphene is 0.5-5 mu m, and the thickness is 0.8-1.2nm; the resin is one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, carboxyl end-capped polyester resin and carboxyl acrylic resin; the modifier is one or more of acrylic acid, gallic acid, dehydroabietic acid methyl ester, dehydroabietic acid, oleic acid, 3', 5' -tetramethyl biphenyl diphenol; the solvent is one or more of butyl carbitol, butyl carbitol acetate, terpineol, alcohol ester twelve, tributyl citrate and diethylene glycol butyl ether; the coupling agent is one or more of silane coupling agents A151, A171 and A172; the dispersing agent is one or more of octyl phenyl polyoxyethylene ether, N-methyl pyrrolidone and polyethylene glycol oleate; the curing agent is one or more of triglycidyl isocyanurate, beta-hydroxyalkylamide, acrylic acid modified hydroxyalkylamide and oleic acid modified hydroxyalkylamide; the accelerator is one or more of carboxylate, methyl hydrazine and amino imine; the wetting agent is one or more of 2.4.7.9-tetramethyl-5-decyne-4.7-diol, oleamide propyl dimethylamine, trimethyl butylene glycol, oleyl alcohol polyoxyethylene ether and fluorine surfactant FC-4430; the preparation method of the HJT solar cell main fine grid general silver paste containing graphene comprises the following specific steps:

Slowly pouring the nano-scale spherical silver powder into a solvent along the wall of a beaker by adopting a constant-temperature stirrer, setting the rotating speed to 600rpm, the temperature to 25 ℃, stirring for 1 hour, then mixing by using a centrifugal machine, and uniformly mixing at the rotating speed of 1200rpm and the temperature to 25 ℃ for 30 minutes to obtain a first mixture;

Step (2) adopting a constant-temperature stirrer, setting the rotating speed to 600rpm, setting the temperature to 60 ℃, adding resin, introducing N2 gas into the bottom of a beaker, sequentially adding a wetting agent, a dispersing agent and a coupling agent into the beaker, slowly adding a filler after uniformly stirring, stirring for 1 hour, and cooling to normal temperature to obtain a second mixture;

sequentially and slowly adding the second mixture, the modifier, the curing agent and the accelerator into the first mixture by adopting a constant-temperature stirrer at normal temperature, setting the rotating speed to 600rpm, stirring for 1 hour, using a centrifugal machine to rotate at 1200rpm and the temperature of 25 ℃ for 30 minutes, and uniformly mixing to obtain a third mixture;

Step (4), adding micron-sized flake silver powder and submicron-sized spherical silver powder into the third mixture, mixing by using a three-roller machine, setting the rotating speed to 750rpm, and mixing for 3 times in the first step, wherein the initial roller gap is 60 mu m and the final roller gap is 30 mu m; secondly, mixing for 3 times, wherein the initial roller gap is 30 mu m and the final roller gap is 15 mu m; thirdly, mixing for 5 times, wherein the initial roller gap is 15 mu m and the final roller gap is 7 mu m; fourth, the initial roller gap is 10 μm and the final roller gap is 4 μm, and the mixture is mixed for 6 times, so that the mixture is uniformly dispersed, and the finished silver paste is obtained.