Humidity and heat resistant N-type TOPCon front fine grid silver paste and preparation method thereof

Abstract

The invention discloses damp-heat-resistant N-type TOPCon front fine grid silver paste. The damp-heat-resistant N-type TOPCon front fine grid silver paste comprises the following components in percentage by weight: 80-91.5 wt% of silver powder, 0.5-4.0 wt% of lead-containing glass powder, 0.05-0.3 wt% of an inorganic additive and 8-9 wt% of an organic carrier. The damp-heat-resistant N-type TOPCon front fine grid silver paste provided by the invention has the advantages of damp-heat resistance and reduced efficiency attenuation after being prepared into a battery piece, the reliability and damp-heat-resistant performance of an assembly are greatly improved, the service life of the assembly is prolonged, and due to the addition of the first-class additive, after the paste is subjected to high-temperature sintering and laser sintering, the service life of the assembly is prolonged. The tellurium element and the cerium element are added, so that the formed glass network structure is more stable, the bond energy of formed covalent bonds and metal bonds is higher, the sensitivity to water vapor and acetic acid is reduced, and the reliability and long-term stability of the assembly are obviously improved; and the second type of additive is added to coat the formed silver-silicon contact surface in the high-temperature sintering and laser sintering processes of the slurry, so that water vapor is prevented from entering the silver-silicon contact position, and the stability of the assembly is greatly improved.

Description

Technical Field

[0001] The 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) is a type of N-type crystalline silicon solar cell, consisting of an ultra-thin tunneling oxide layer and a doped polysilicon layer, which can provide excellent surface passivation for the back of the silicon wafer. The ultra-thin oxide layer can block the recombination of minority holes while allowing majority electrons to tunnel into doped polysilicon. The electrons entering the polysilicon are laterally transmitted and collected by the metal electrode. This structure can significantly improve the opening voltage and efficiency of the cell. Although TOPCon cells are highly efficient, they still have shortcomings in long-term stability and resistance to moisture and heat.

[0003] After the crystalline silicon solar cell is encapsulated with single or double glass, working under high temperature conditions for a long time will accelerate the aging of the encapsulation material, and the penetration of temperature and moisture will cause the cell to corrode, the metallization layer to degrade, and the EVA to decompose and produce acetic acid, thus affecting the battery performance. For TOPCon cells, the characteristics of the front fine grid material will affect its resistance to moisture and heat, and each battery manufacturer has a higher demand for moisture and heat resistant solar electronic paste. In order to solve the problem that the water vapor and acetic acid of the front fine grid corrode the solar cell in a high temperature and high humidity environment, destroy the formed contact network structure, and cause the front fine grid to attenuate and stabilize, a battery silver paste with good moisture and heat resistance is needed. 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 purposes and other advantages of the present invention, a moisture-heat resistant N-type TOPCon front fine grid silver paste is provided, characterized in that it includes the following components calculated by percentage: 80-91.5wt% of silver powder, 0.5%-4.0wt% of lead-containing glass powder, 0.05-0.3wt% of inorganic additives, and 8-10wt% 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 dodecaned, 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: 20-50wt% PbO, 1-30wt% SiO2, 1-10wt% ZnO2, 5-30wt% B2O3, and 0-10wt% 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: Mix 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 cool to obtain an organic carrier;

[0015] Step 2: Mix the organic carrier with silver powder, lead 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 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: raw materials are weighed according to the mass percentage of each component of the lead-containing glass powder to prepare a mixture, which is loaded into a high-temperature resistant ceramic crucible and then placed in a muffle furnace for heating and melting, the heating temperature being 1000°C and the insulation time being 30 minutes, the molten glass powder slurry is poured onto a double-roll mill with a cooling system for cold extraction, drying, and crushing, and the glass powder is obtained by air flow grinding.

[0017] The present invention includes at least the following beneficial effects: the moisture and heat resistant N-type TOPCon front fine grid silver paste provided by the present invention has the advantages of moisture and heat resistance and reduced efficiency decay after being prepared into a battery cell, which greatly improves the reliability and moisture and heat resistance of the component and extends the service life of the component; wherein, the addition of the first type of additives, after the slurry 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 slurry, forms a coating on the formed silver-silicon contact surface, thereby avoiding water vapor from penetrating into 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 it according 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: Mix 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 of 2.3μm, glass transition temperature of 450℃, softening temperature of 503℃) and the first type of inorganic additives (1.5kg tellurium oxide, 0.3kg cerium oxide, 0.2kg graphene) are mixed, stirred at 500rpm in a planetary stirring kettle for 1h, and rolled 8 times by a three-roll grinder until the slurry fineness is qualified after stirring evenly, and the finished product of the moisture-heat-resistant N-type TOPCon front fine grid silver paste is obtained. Among them, the preparation process of lead-containing glass powder is: 7kg PbO, 6kg SiO2, 4kg B2O3, 2kg Bi2O3, 1kg ZnO2 are mixed evenly, and then loaded into a high-temperature resistant ceramic crucible and placed in a muffle furnace for heating and melting. The heating temperature is 1000℃ and the insulation 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.

[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, and stirred and dispersed at 600 rpm, and then allowed to stand and 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 the second type of inorganic additives (0.3kg cerium oxide, 0.2kg solder paste) are mixed, stirred at 500rpm in a planetary stirring kettle for 1h, and after stirring evenly, rolled 8 times by a three-roll grinder until the slurry fineness is qualified, and the finished product of the moisture-heat resistant N-type TOPCon front fine grid silver paste is obtained. Among them, the preparation process of lead-containing glass powder is: 7kg PbO, 7kg SiO2, 3kg B2O3, 2kg Bi2O3, 1kg ZnO2 are mixed evenly, and then loaded into a high-temperature resistant ceramic crucible and placed in a muffle furnace for heating and melting. The heating temperature is 1000℃ and the insulation 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 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, and the rest are consistent with Example 1.

[0031] Comparative Example 3

[0032] The specific implementation method of this comparative example is the same as 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 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 remaining components are added in amounts of: 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 prepared into battery cells, and the components were packaged with backplanes, adhesive films, glass, etc., and subjected to moisture and heat resistance tests to compare the efficiency attenuation before and after the tests. The test results are shown in Table 1 below.

[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 the crystalline silicon solar cells, and 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. Example 1-2 has 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 Example 1-2 can simply and efficiently balance the resistance to moisture and heat 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 as above, they are not limited to the applications listed in the specification and the implementation modes. 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 moisture and heat resistant N-type TOPCon front fine grid silver paste, characterized in that: The composition includes the following components by percentage: 80-91.5 wt % of silver powder, 0.5-4.0 wt % of lead-containing glass powder, 0.05-3 wt % of inorganic additives, and 8-9 wt % of organic carrier.

2. The heat and humidity 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 to 0.60 cm 2 / g.

3. The heat and humidity 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 and humidity 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 dodecaned and butyl diglycol in a mass ratio of 30-60:5-10:10-20:1-5.

5. The heat and humidity 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 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.

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

8. The heat and humidity resistant N-type TOPCon front fine grid silver paste according to claim 1, characterized in that: 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% 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. 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.

9. A method for preparing a moisture-heat resistant N-type TOPCon front fine grid silver paste according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1: Mix 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 cool to obtain an organic carrier; Step 2: Mix the organic carrier with silver powder, lead 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 moisture-heat-resistant N-type TOPCon front fine grid silver paste.

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