Anti-wet-heat n-type topcon front fine grid silver paste and preparation method thereof

Abstract

The application discloses a kind of anti-humid heat N type TOPCon front fine grid silver paste, including the following components by percentage calculation: silver powder 80~91.5wt%, lead-containing glass powder 0.5%~4.0wt%, inorganic additive 0.05~0.3wt%, organic carrier 8~9wt%.The anti-humid heat N type TOPCon front fine grid silver paste provided by the application has the advantages of moisture resistance, efficiency decay reduction after being prepared into battery piece, greatly improves the reliability and moisture resistance of module, prolongs the service life of module, the addition of first additive, after the paste is sintered and laser sintered at high temperature, the addition of tellurium element and cerium element makes the glass network structure more stable, the covalent bond and metal bond energy formed are higher, the sensitivity to water vapor and acetic acid is reduced, the reliability and long-term stability of module are significantly improved;The addition of second additive forms a coating on the silver-silicon contact surface formed during high-temperature sintering and laser sintering of the paste, preventing water vapor from penetrating into the silver-silicon contact position, thus greatly improving the stability of the module.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic electronic pastes, and more specifically relates to a moisture-heat resistant N-type TOPCon front fine grid silver paste and a preparation method thereof. Background Art

[0002] TOPCon (Tunneling Oxide Passivated Contact Solar Cell) cells are a type of N-type crystalline silicon solar cell. They consist of an ultra-thin tunneling oxide layer and a doped polysilicon layer, providing superior surface passivation for the backside of the silicon wafer. The ultra-thin oxide layer allows majority electrons to tunnel into the doped polysilicon while preventing minority holes from recombinating. Electrons entering the polysilicon are then transported laterally and collected by metal electrodes. This structure significantly improves the cell's turn-on voltage and efficiency. Although TOPCon cells offer high efficiency, they still face challenges in long-term stability and resistance to humidity and heat.

[0003] After single- or double-glass encapsulation of crystalline silicon solar cells, prolonged operation under high-temperature conditions accelerates the aging of the encapsulation material. Furthermore, the combined effects of temperature and moisture penetration can lead to cell corrosion, metallization degradation, and EVA decomposition, producing acetic acid, which in turn affects cell performance. For TOPCon cells, the properties of the front-side fine grid material affect their resistance to moisture and heat, leading to higher demands for moisture-resistant solar electronic pastes from various cell manufacturers. To address the issue of front-side fine grid corrosion caused by moisture and acetic acid in high-temperature and high-humidity environments, which damages the contact network structure and leads to attenuation and stability of the front-side fine grid, a silver paste with excellent moisture and heat resistance is required. Summary of the Invention

[0004] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0005] In order to achieve these objects and other advantages of the present invention, a moisture- and heat-resistant N-type TOPCon front fine grid silver paste is provided, characterized in that it includes the following components, calculated by percentage: 80-91.5 wt% of silver powder, 0.5%-4.0 wt% of lead-containing glass powder, 0.05-0.3 wt% of inorganic additives, and 8-10 wt% of organic carrier.

[0006] Preferably, the average particle size of the silver powder is 0.3-4.9 μm, and the tap density is 3.0-7.0 g / cm 3 , with a specific surface area of ​​0.3 to 0.60 cm 2 / g.

[0007] Preferably, the organic carrier comprises an organic solvent, a resin and an auxiliary agent, and the mass ratio of the organic solvent, the resin and the auxiliary agent is 70-85:3-10:3-7.

[0008] Preferably, the organic solvent is a mixture of diethylene glycol butyl ether acetate, dimethyl phthalate, alcohol ester dodecanedia, and diethylene glycol butyl ether in a mass ratio of 30-60:5-10:10-20:1-5.

[0009] Preferably, the resin is one or more of ethyl cellulose, polyvinyl butyral, cellulose acetate, polystyrene resin, styrene-ethylene block copolymer, propylene styrene block copolymer, and polymethyl styrene.

[0010] Preferably, the auxiliary agent includes a thixotropic agent, a release agent and a dispersant, the thixotropic agent is one or more of polyacetamide wax, hydrogenated castor oil or polyurea, the release agent is silicone oil, and the dispersant is one or more of oleic acid and tributyl phosphate.

[0011] Preferably, the lead-containing glass powder comprises the following components in percentage: 20-50 wt% PbO, 1-30 wt% SiO2, 1-10 wt% ZnO2, 5-30 wt% B2O3, and 0-10 wt% Bi2O3.

[0012] Preferably, the inorganic additive is a first type of additive or a second type of additive, the first type of additive is a Te-Ce-graphene system additive, and the first type of additive includes, based on the mass percentage of the first type of additive in the slurry: 1.0wt% to 1.5wt% tellurium oxide, 0.1 to 0.3wt% cerium oxide, and 0.1 to 0.2wt% graphene; the second type of additive is a Ce-tin system additive, and based on the mass percentage of the second type of additive in the slurry, the second type of additive includes: 0.1 to 0.8wt% cerium oxide, 0.1 to 5wt% solder paste, wherein the tellurium oxide particle size is 5 to 10μm, the cerium oxide particle size is 50nm to 1μm, the graphene particle size is 0.5 to 5μm, and the solder paste particle size is 1 to 10μm.

[0013] The present invention also provides a method for preparing a moisture-heat resistant N-type TOPCon front fine grid silver paste, comprising the following steps:

[0014] Step 1: After mixing the organic solvent, resin, and additive, heat them at a constant temperature of 50-90° C. for 1-3 hours, stir and disperse them at 400-800 rpm, and then let them stand and cool to obtain an organic carrier;

[0015] Step 2: Mix the organic carrier with silver powder, lead-containing glass powder and inorganic additives, stir at a speed of 400-600 rpm for 2-3 hours, and after stirring evenly, roll through a three-roll grinder 6-8 times until the slurry fineness meets the requirements, thereby obtaining a finished product of the moisture-heat-resistant N-type TOPCon front fine grid silver paste.

[0016] Preferably, the preparation process of the lead-containing glass powder is as follows: the raw materials are weighed according to the mass percentage of each component of the lead-containing glass powder and then a mixture is prepared, which is placed in a high-temperature resistant ceramic crucible and then placed in a muffle furnace for heating and melting. The heating temperature is 1000°C and the insulation time is 30 minutes. The molten glass powder slurry is poured onto a roller mill with a cooling system for cold extraction, drying, crushing, and obtaining glass powder by air flow grinding.

[0017] The present invention includes at least the following beneficial effects: the moisture-heat resistant N-type TOPCon front fine grid silver paste provided by the present invention has the advantages of moisture-heat resistance and reduced efficiency decay after being prepared into a solar cell, which greatly improves the reliability and moisture-heat resistance of the component and extends the service life of the component; wherein, the addition of the first type of additives, after the paste is subjected to high-temperature sintering and laser sintering, the addition of tellurium and cerium elements makes the formed glass network structure more stable, the formed covalent bonds and metal bonds have higher bond energies, and the sensitivity to water vapor and acetic acid is reduced, which significantly improves the reliability and long-term stability of the component; wherein, the addition of the second type of additives, during the high-temperature sintering and laser sintering of the paste, forms a coating on the formed silver-silicon contact surface, thereby avoiding water vapor from penetrating the silver-silicon contact position, thereby greatly improving the stability of the component. DETAILED DESCRIPTION

[0018] The present invention is described in further detail below so that those skilled in the art can implement the invention with reference to the description.

[0019] Example 1

[0020] A method for preparing a moisture-heat resistant N-type TOPCon front fine grid silver paste comprises the following steps:

[0021] Step 1: 10.6 kg of diethylene glycol butyl ether acetate, 2 kg of dimethyl phthalate, 4 kg of alcohol ester dodecahydrate, 0.4 kg of diethylene glycol dibutyl ether, 1.4 kg of polystyrene resin, 1 kg of polyvinyl butyral, and 0.6 kg of polymethyl styrene were mixed and heated at a constant temperature of 80 ° C for 2 h, and stirred and dispersed at 600 rpm, and then allowed to stand and cool to obtain an organic carrier;

[0022] Step 2: 8.7 kg of organic carrier and 86.3 kg of silver powder (particle size 3.5 μm; tap density 6.0 g / cm 3 , with a specific surface area of ​​0.56 cm 2 / g), 3kg lead-containing glass powder (particle size 2.3μm, glass transition temperature 450℃, softening temperature 503℃) and the first type of inorganic additives (1.5kg tellurium oxide, 0.3kg cerium oxide, 0.2kg graphene) were mixed and stirred at 500rpm in a planetary stirred tank for 1 hour. After stirring evenly, the mixture was rolled 8 times on a three-roll mill until the slurry fineness met the requirements, thus obtaining the finished product of the moisture-heat-resistant N-type TOPCon front fine grid silver paste. The lead-containing glass powder preparation process is as follows: 7kg PbO, 6kg SiO2, 4kg B2O3, 2kg Bi2O3, and 1kg ZnO2 were mixed evenly, then placed in a high-temperature resistant ceramic crucible and heated in a muffle furnace at 1000℃ for 30 minutes. The molten glass powder slurry was poured onto a roller mill with a cooling system for cold extraction, drying, crushing, and then jet milling to obtain glass powder.

[0023] Example 2

[0024] A method for preparing a moisture-heat resistant N-type TOPCon front fine grid silver paste comprises the following steps:

[0025] Step 1: 10.6 kg of diethylene glycol butyl ether acetate, 2 kg of dimethyl phthalate, 4 kg of alcohol ester dodecahydrate, 0.4 kg of diethylene glycol dibutyl ether, 1.4 kg of polystyrene resin, 1 kg of polyvinyl butyral, and 3 kg of polymethyl styrene were mixed and heated at a constant temperature of 80 ° C for 2 h, stirred and dispersed at 600 rpm, and then allowed to cool to obtain an organic carrier;

[0026] Step 2: Mix 8.7 kg of organic carrier and 87.8 kg of silver powder (particle size 3.5 μm; tap density 6.0 g / cm 3 , with a specific surface area of ​​0.56 cm 2 / g), 3kg lead-containing glass powder (particle size of 2.3μm, glass transition temperature of 450℃, softening temperature of 503℃) and a second type of inorganic additives (0.3kg cerium oxide, 0.2kg solder paste) are mixed and stirred at 500rpm in a planetary stirring kettle for 1h. After stirring evenly, the mixture is rolled 8 times by a three-roll mill until the slurry fineness meets the requirements, thus obtaining the finished product of the moisture-heat-resistant N-type TOPCon front fine grid silver paste. The preparation process of the lead-containing glass powder is as follows: 7kg PbO, 7kg SiO2, 3kg B2O3, 2kg Bi2O3, and 1kg ZnO2 are mixed evenly, then placed in a high-temperature resistant ceramic crucible and placed in a muffle furnace for heating and melting. The heating temperature is 1000℃ and the holding time is 30min. The molten glass powder slurry is poured on a roller mill with a cooling system for cold extraction, drying, crushing, and obtaining glass powder by air flow milling.

[0027] Comparative Example 1

[0028] The specific implementation of this comparative example is the same as Example 1, except that no inorganic additives are added, and the addition amounts of the remaining components are: 88.3 kg silver powder, 3 kg lead-containing glass powder and 8.7 kg organic carrier, and the rest are consistent with Example 1.

[0029] Comparative Example 2

[0030] The specific implementation method of this comparative example is the same as that of Example 1, except that in step 2, only 1.5 kg of tellurium oxide is added as an inorganic additive (corresponding to 1.5 wt% of the tellurium oxide content in Example 1), and the addition amounts of the remaining components are: 86.8 kg of silver powder, 3 kg of lead-containing glass powder and 8.7 kg of organic carrier. The rest are consistent with Example 1.

[0031] Comparative Example 3

[0032] The specific implementation method of this comparative example is the same as that of Example 1, except that in step 2, only 0.3 kg of cerium oxide is added as an inorganic additive (corresponding to 0.3 wt% of the cerium oxide content in Example 1), and the addition amounts of the remaining components are: 88 kg of silver powder, 3 kg of lead-containing glass powder and 8.7 kg of organic carrier, and the rest are consistent with Example 1.

[0033] Comparative Example 4

[0034] The specific implementation method of this comparative example is the same as that of Example 1, except that in step 2, only 0.2 kg of graphene is added as an inorganic additive (corresponding to 0.2 wt% of the graphene content in Example 1), and the addition amounts of the remaining components are: 88.1 kg of silver powder, 3 kg of lead-containing glass powder and 8.7 kg of organic carrier, and the rest are consistent with Example 1.

[0035] Comparative Example 5

[0036] The specific implementation method of this comparative example is the same as Example 2, except that in step 2, only 0.2 kg of solder paste is added as an inorganic additive (corresponding to 0.2 wt% of the solder paste content in Example 2), and the addition amounts of the remaining components are: 88.1 kg of silver powder, 3 kg of lead-containing glass powder and 8.7 kg of organic carrier, and the rest are consistent with Example 2.

[0037] The slurries prepared in Examples 1-2 and Comparative Examples 1-5 were used to prepare solar cells, which were then packaged with backsheets, adhesive films, and glass. Heat and humidity resistance tests were conducted to compare the efficiency attenuation before and after the tests. The test results are shown in Table 1.

[0038] Table 1

[0039]

[0040]

[0041] Comparative Examples 1, 3, and 4 have large differences after attenuation and poor efficiency, which will affect the long-term stability of crystalline silicon solar cells. There are defects in the microstructure and the efficiency is greatly reduced. Although the efficiency reduction of Comparative Examples 2 and 5 is smaller after attenuation, the online efficiency before attenuation is unqualified. Examples 1-2 have higher efficiency, and the resistance to acetic acid and moisture and heat are greatly improved. In short, after the raw materials in the additives are added separately to Comparative Examples 1-5 and fired, the prepared slurry is difficult to balance the efficiency of the cell and the resistance to moisture and heat; while the composite additives of Examples 1-2 can simply and efficiently balance the moisture and heat resistance of the silver paste and the efficiency of the cell, and have universal applicability.

[0042] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A heat and humidity resistant N-type TOPCon front fine grid silver paste, characterized in that: The components are as follows: silver powder 80~91.5wt%, lead glass powder 0.5%~4.0wt%, inorganic additives 0.05~3wt%, organic carrier 8~9wt%; The inorganic additive is a first type of additive or a second type of additive. The first type of additive is a Te-Ce-graphene system additive. Based on the mass percentage of the first type of additive in the slurry, the first type of additive includes: 1.0wt%~1.5wt% tellurium oxide, 0.1~0.3wt% cerium oxide, and 0.1~0.2wt% graphene. The second type of additive is a Ce-tin system additive. Based on the mass percentage of the second type of additive in the slurry, the second type of additive includes: 0.1~0.8wt% cerium oxide, 0.1~5wt% solder paste, wherein the tellurium oxide particle size is 5~10μm, the cerium oxide particle size is 50nm~1μm, the graphene particle size is 0.5~5μm, and the solder paste particle size is 1~10μm.

2. The heat-resistant N-type TOPCon front fine grid silver paste according to claim 1, characterized in that: The average particle size of the silver powder is 0.3-4.9 μm, and the tap density is 3.0-7.0 g / cm 3 , with a specific surface area of ​​0.3~0.60cm 2 / g.

3. The heat-resistant N-type TOPCon front fine grid silver paste according to claim 1, characterized in that: The organic carrier comprises an organic solvent, a resin and an auxiliary agent, and the mass ratio of the organic solvent, the resin and the auxiliary agent is 70-85:3-10:3-7.

4. The heat-resistant N-type TOPCon front fine grid silver paste according to claim 3, characterized in that: The organic solvent is prepared by mixing butyl diglycol acetate, dimethyl phthalate, alcohol ester dodecanedia, and butyl diglycol in a mass ratio of 30-60:5-10:10-20:1-5.

5. The heat-resistant N-type TOPCon front fine grid silver paste according to claim 3, characterized in that: The resin is one or more of ethyl cellulose, polyvinyl butyral, cellulose acetate, polystyrene resin, styrene-ethylene block copolymer, propylene styrene block copolymer, and polymethyl styrene.

6. The heat and humidity resistant N-type TOPCon front fine grid silver paste according to claim 3, characterized in that: The auxiliary agent includes a thixotropic agent, a release agent and a dispersant. The thixotropic agent is one or more of polyamide wax, hydrogenated castor oil or polyurea. The release agent is silicone oil. The dispersant is one or more of oleic acid and tributyl phosphate.

7. The heat-resistant N-type TOPCon front fine grid silver paste according to claim 1, characterized in that: The lead-containing glass powder includes the following components in percentage: 20~50wt% PbO, 1~30wt% SiO2, 1~10wt% ZnO2, 5~30wt% B2O3, and 0~10wt% Bi2O3.

8. A method for preparing the heat and humidity resistant N-type TOPCon front fine grid silver paste according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1: After mixing the organic solvent, resin, and additive, heat at a constant temperature of 50-90°C for 1-3 hours, stir and disperse at 400-800 rpm, and then stand and cool to obtain an organic carrier; Step 2: Mix the organic carrier with silver powder, lead-containing glass powder and inorganic additives, stir at a speed of 400-600 rpm for 2-3 hours, and after stirring evenly, roll the mixture through a three-roll mill 6-8 times until the slurry fineness meets the requirements, thereby obtaining the finished product of the moisture-heat-resistant N-type TOPCon front fine grid silver paste.

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