Composite glass powder, solar cell front silver paste and preparation method thereof

Abstract

The present invention relates to the field of electronic materials, specifically to H01B1 / 22 and G01N1 / 28. More specifically, the present invention relates to a composite glass powder, a front silver paste for solar cells, and a preparation method thereof. The composite glass powder for the front silver paste of high-opening-voltage PERC solar cells comprises a vanadium-phosphorus-barium system glass powder and a lead-telluride system glass powder. The composite glass powder for the front silver paste of high-opening-voltage PERC solar cells of the present invention comprises a vanadium-phosphorus-barium system glass powder and a lead-telluride system glass powder. The two glass systems have complementary functions. The lead-telluride system glass powder has a good corrosion effect on the anti-reflection coating on the surface of crystalline silicon solar cells, while the vanadium-phosphorus-barium system glass powder mainly serves as a corrosion buffer. The lead-telluride system glass powder has a relatively low softening point (350-415°C). As the sintering temperature increases, it first corrodes the SiNx film layer, and then the silver grains form a conductive channel. The vanadium-phosphorus-barium system glass powder has a relatively high softening point (386-458°C) and is relatively inert to the SiNx film layer, hindering the silver grains in the conductive channel from further penetrating the emitter.

Description

Technical Field

[0001] The present invention relates to the field of electronic materials, in particular to H01B1 / 22, in particular to G01N1 / 28, and more particularly to a composite glass powder, a front silver paste for a solar cell, and a preparation method thereof. Background Art

[0002] The front silver paste commonly used in the industry at present is composed of silver powder, glass powder and organic carrier (mainly resin and organic solvent, etc.), among which the resin and solvent volatilize after high-temperature sintering. Therefore, the main components of the battery grid are silver powder and glass powder. Research on glass powder mainly focuses on the role of glass powder in the conductive paste. The glass powder in the front silver paste currently available on the market generally uses a single lead-containing system glass, such as Chinese patents CN201910310456, CN201910310455, etc. However, the PbO in the glass powder is extremely active. Although it is beneficial to fully corrode SiNx and form a good ohmic contact, the corrosion depth is difficult to control. If the silver paste has a narrow adaptation window, it is often easy to damage the PN junction with fluctuations in the sintering temperature, resulting in a decrease in open-circuit voltage and affecting efficiency. Therefore, how to better balance the contact resistance and open-circuit voltage on PERC solar cells is currently a difficulty in the development of front silver paste technology. Summary of the Invention

[0003] In response to some problems existing in the prior art, the first aspect of the present invention provides a composite glass powder for high-opening-voltage PERC solar cell front silver paste, comprising vanadium-phosphorus-barium system glass powder and lead-tellurium system glass powder.

[0004] Preferably, the mass ratio of the vanadium-phosphorus-barium system glass powder to the lead-tellurium system glass powder is 1:(1.5-2.5), and the mass ratio is preferably 1:2.

[0005] In one embodiment, the glass transition temperature of the vanadium-phosphorus-barium system glass powder is 215-350°C, and preferably, the softening temperature is 386-458°C.

[0006] In one embodiment, the lead-tellurium system glass powder has a glass transition temperature of 200-300°C, preferably, a softening temperature of 350-415°C.

[0007] Lead-telluride glass frit forms a conductive path on solar cells by etching crystalline silicon. During the silver paste sintering process, it also acts as a transmission medium between the solar cell and the silver powder in the paste. As the temperature rises, it melts and encapsulates the silver particles, dissolving the silver powder in the molten glass phase and preventing vertical growth. Vanadium-phosphorus-barium glass frit increases the viscosity of the glass phase, making the silver powder denser after sintering.

[0008] The composite glass powder of the present application solves the problem that the single lead-containing system glass is highly corrosive and causes great damage to the open-circuit voltage of the electrical performance. The composite glass powder is made into a front silver paste and used on PERC solar cells. It has the characteristics of high open voltage and high efficiency, and can well balance the contact resistance and open-circuit voltage to maintain good electrical performance.

[0009] In one embodiment, the vanadium-phosphorus-barium system glass powder includes P2O5, V2O 5、 One or more of BaO, MnO, Na2O, K2O, WO3.

[0010] Preferably, the vanadium-phosphorus-barium system glass powder further includes sulfide.

[0011] The sulfide in this application is not particularly limited, and those skilled in the art can make a conventional selection, preferably zinc sulfide.

[0012] In a preferred embodiment, the vanadium-phosphorus-barium system glass powder comprises 15-37% P2O5, 20-35% V2O 5、 5.5-28% BaO, 3-10% MnO, 0-3.5% Na2O, 0.5-5.5% K2O, 1-15% sulfide, 2-10% WO3.

[0013] In a more preferred embodiment, the vanadium-phosphorus-barium system glass powder comprises 19-29% P2O5, 29-35% V2O 5、 10-23% BaO, 3-10% MnO, 1-3% Na2O, 1.5-5% K2O, 5-12% sulfide, 3-10% WO3.

[0014] In one embodiment, the lead-tellurium system glass powder comprises one or more components of PbO, TeO2, alkali metal oxides, TiO2, and P2O5.

[0015] In a preferred embodiment, the lead-tellurium system glass powder comprises, by mass percentage, 10.5-32% PbO, 55-78% TeO2, 0.1-3.6% alkali metal oxides, 0.5-6% TiO2, and 1-10% P2O5.

[0016] In a more preferred embodiment, the lead-tellurium system glass powder comprises, by mass percentage, 18-27% PbO, 62-70.5% TeO2, 1-3% alkali metal oxides, 1-4% TiO2, and 2.5-8% P2O5.

[0017] In the present application, the alkali metal oxide is not particularly limited, and those skilled in the art can make conventional selections, preferably Li2O.

[0018] In one embodiment, the particle size distributions of the vanadium-phosphorus-barium system glass powder and the lead-tellurium system glass powder are respectively 0.4-7 μm.

[0019] A second aspect of the present invention provides a method for preparing the composite glass powder for the front silver paste of the high opening voltage PERC solar cell, comprising the following steps:

[0020] (1) mixing the components of vanadium-phosphorus-barium system glass powder and lead-tellurium system glass powder respectively to obtain a mixture 1 of vanadium-phosphorus-barium system glass powder and a mixture 2 of lead-tellurium system glass powder;

[0021] (2) Mixture 1 and Mixture 2 are heated and melted respectively, and then quenched;

[0022] (3) The quenched mixtures 1 and 2 are dried respectively, and then crushed to produce vanadium-phosphorus-barium system glass powder and lead-tellurium system glass powder of corresponding particle sizes.

[0023] Preferably, the temperature for heating and melting in step (2) is 900-1250° C., and the time is 20-35 min.

[0024] A third aspect of the present invention provides a front silver paste for a solar cell, wherein the raw materials for preparing the front silver paste for the solar cell include the composite glass powder for the high opening voltage PERC solar cell.

[0025] In one embodiment, the solar cell front silver paste further includes silver powder, an organic carrier, and additives.

[0026] In one embodiment, the raw materials for preparing the solar cell front silver paste include, by weight, 2-5 parts of composite glass powder, 80-90 parts of silver powder, 5-12 parts of organic vehicle, and 1-5 parts of additives.

[0027] Preferably, the raw materials for preparing the solar cell front silver paste include, by mass, 2.4 parts of composite glass powder, 88 parts of silver powder, 8.4 parts of organic carrier, and 1.2 parts of additives.

[0028] A fourth aspect of the present invention provides a PERC crystalline silicon solar cell, on which the silver paste is screen-printed.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The composite glass powder for the front silver paste of a high-opening-voltage PERC solar cell of the present invention comprises a vanadium-phosphorus-barium system glass powder and a lead-tellurium system glass powder. The two glass systems have complementary functions. The lead-tellurium system glass powder has a good corrosion effect on the anti-reflection film on the surface of the crystalline silicon solar cell. The vanadium-phosphorus-barium system glass powder mainly plays a role in buffering corrosion. The lead-tellurium system glass powder has a relatively low softening point (350-415°C). As the sintering temperature increases, the SiNx film layer is first corroded, and then the silver grains form a conductive channel. The vanadium-phosphorus-barium system glass powder has a relatively high softening point (386-458°C), which is also It is relatively inert in reacting with the SiNx film layer, and hinders the silver grains from further penetrating the emitter in the conductive channel. In addition, the present invention specifically introduces ZnS into the vanadium-phosphorus-barium system glass powder component to enhance the stability of the glass while incorporating sulfur ions, so that the glass has typical semiconductor glass functions, which is beneficial to the electron cross-flow and increase the conductivity. Therefore, the front silver paste prepared by the composite glass powder in the present invention is printed on the PERC solar cell, which can well take into account high opening voltage and contact resistance, and make up for the shortcomings caused by the use of single lead glass for the front silver paste in the current PERC battery market. DETAILED DESCRIPTION

[0031] The present invention is described below by way of specific embodiments, but is not limited to the specific embodiments given below.

[0032] Example 1

[0033] A composite glass powder for high-voltage PERC solar cell front silver paste is a composite of vanadium-phosphorus-barium system glass powder and lead-tellurium system glass powder.

[0034] The components of the vanadium-phosphorus-barium system glass powder and the mass percentage of each component are as follows:

[0035] 29% P2O5, 35% V2O5, 17% BaO, 3% MnO, 3% Na2O, 1.5% K2O, 7% ZnS, 4.5% WO3. The vanadium-phosphorus-barium system glass powder has a glass transition temperature of 220°C and a softening temperature of 390°C.

[0036] The method for preparing the vanadium-phosphorus-barium system glass powder specifically comprises the following steps:

[0037] (1) Weigh each component according to its mass percentage and prepare the mixture;

[0038] (2) the mixture is placed in a high-temperature resistant corundum crucible and then placed in a high-temperature muffle furnace for heating and melting, wherein the heating temperature is 1200° C. and the holding time is 30 minutes;

[0039] (3) Pour the melted high-temperature glass into deionized water and rapidly quench;

[0040] (4) Place the water-quenched glass material in a 100°C oven to dry out the moisture;

[0041] (5) crushing the dried glass material into a particle size of less than 200 mesh using a crusher;

[0042] (6) The crushed powder is put into a jet mill to prepare ultrafine glass powder of 0.4-7 μm.

[0043] Among them, the components of the lead-tellurium system glass powder and the mass fraction of each component are as follows:

[0044] 27% PbO, 62% TeO2, 2% Li2O, 1% TiO2, 8% P2O5. The lead-tellurium system glass powder has a glass transition temperature of 205°C and a softening temperature of 365°C.

[0045] The preparation method of the lead-tellurium system glass powder specifically comprises the following steps:

[0046] (1) Weigh each component according to its mass percentage and prepare the mixture;

[0047] (2) the mixture is placed in a high-temperature resistant corundum crucible and then placed in a high-temperature muffle furnace for heating and melting, wherein the heating temperature is 950° C. and the holding time is 20 minutes;

[0048] (3) Pour the melted high-temperature glass into deionized water and rapidly quench;

[0049] (4) Place the water-quenched glass material in a 100°C oven to dry out the moisture;

[0050] (5) crushing the dried glass material into a particle size of less than 200 mesh using a crusher;

[0051] (6) The crushed powder is put into a jet mill to prepare ultrafine glass powder of 0.4-7 μm.

[0052] Example 2

[0053] A composite glass powder for high-voltage PERC solar cell front silver paste is a composite of vanadium-phosphorus-barium system glass powder and lead-tellurium system glass powder.

[0054] The components of the vanadium-phosphorus-barium system glass powder and the mass percentage of each component are as follows:

[0055] 26% P2O5, 32% V2O 5、 10% BaO, 8% MnO, 1% Na2O, 3% K2O, 10% ZnS, 10% WO3. The vanadium-phosphorus-barium system glass powder has a glass transition temperature of 265°C and a softening temperature of 430°C.

[0056] The method for preparing the vanadium-phosphorus-barium system glass powder is the same as that in Example 1, except that the heating temperature in step (2) is 1000°C.

[0057] The components and mass fractions of the lead-tellurium system glass powder are as follows:

[0058] 23% PbO, 68% TeO2, 1% Li2O, 2% TiO2, 6% P2O5. The lead-tellurium system glass powder has a glass transition temperature of 215°C and a softening temperature of 381°C.

[0059] The preparation method of the lead-tellurium system glass powder is the same as that of Example 1, except that the heating temperature in step (2) is 1000° C. and the holding time is 25 minutes.

[0060] Example 3

[0061] A composite glass powder for high-opening-voltage PERC solar cell front silver paste and a preparation method thereof, wherein the composite glass powder is a composite of vanadium-phosphorus-barium system glass powder and lead-tellurium system glass powder.

[0062] The components of the vanadium-phosphorus-barium system glass powder and the mass percentage of each component are as follows:

[0063] 19% P2O5, 35% V2O 5、 22% BaO, 6% MnO, 1% Na2O, 2% K2O, 9% ZnS, 6% WO3. The vanadium-phosphorus-barium system glass powder has a glass transition temperature of 231°C and a softening temperature of 405°C.

[0064] The method for preparing the vanadium-phosphorus-barium system glass powder is the same as that in Example 1, except that in step (2), the heating temperature is 1250° C. and the holding time is 35 minutes.

[0065] Among them, the components of the lead-tellurium system glass powder and the mass fraction of each component are as follows:

[0066] 28% PbO, 66% TeO2, 1.5% Li2O, 2% TiO2, 2.5% P2O5. The lead-tellurium system glass powder has a glass transition temperature of 265°C and a softening temperature of 400°C.

[0067] The method for preparing the lead-tellurium system glass powder is the same as that in Example 1, except that the heating temperature in step (2) is 900° C. and the holding time is 25 minutes.

[0068] Example 4

[0069] A composite glass powder for high-voltage PERC solar cell front silver paste is a composite of vanadium-phosphorus-barium system glass powder and lead-tellurium system glass powder.

[0070] The components of the vanadium-phosphorus-barium system glass powder and the mass percentage of each component are as follows:

[0071] 23% P2O5, 29% V2O 5、 16% BaO, 10% MnO, 2% Na2O, 3% K2O, 12% ZnS, 5% WO3. The vanadium-phosphorus-barium system glass powder has a glass transition temperature of 290°C and a softening temperature of 455°C.

[0072] The method for preparing the vanadium-phosphorus-barium system glass powder is the same as that in Example 1, except that the heating temperature in step (2) is 1150° C. and the holding time is 30 minutes.

[0073] Among them, the components of the lead-tellurium system glass powder and the mass fraction of each component are as follows:

[0074] 22% PbO, 66% TeO2, 3% Li2O, 4% TiO2, 5% P2O5. The lead-tellurium system glass powder has a glass transition temperature of 253°C and a softening temperature of 391°C.

[0075] The preparation method of lead-tellurium system glass powder is the same as that of Example 1, except that the heating temperature in step (2) is 900° C. and the holding time is 20 minutes.

[0076] Example 5

[0077] A composite glass powder for high-voltage PERC solar cell front silver paste is a composite of vanadium-phosphorus-barium system glass powder and lead-tellurium system glass powder.

[0078] The components of the vanadium-phosphorus-barium system glass powder and the mass percentage of each component are as follows:

[0079] 24% P2O5, 30% V2O 5、 25% BaO, 8% MnO, 5% K2O, 5% ZnS, 3% WO3. The glass transition temperature of the vanadium-phosphorus-barium system glass powder is 259°C and the softening temperature is 423°C.

[0080] The method for preparing the vanadium-phosphorus-barium system glass powder is the same as that in Example 1, except that the heating temperature in step (2) is 1100° C. and the holding time is 35 minutes.

[0081] Among them, the components of the lead-tellurium system glass powder and the mass fraction of each component are as follows:

[0082] 18% PbO, 70.5% TeO2, 2.5% Li2O, 3.5% TiO2, 5.5% P2O5. The lead-tellurium system glass powder has a glass transition temperature of 225°C and a softening temperature of 385°C.

[0083] The preparation method of the lead-tellurium system glass powder is the same as that of Example 1, except that the holding time in step (2) is 25 minutes.

[0084] The composite glass powder prepared in Examples 1-5 was used with silver powder, additives, and an organic vehicle to prepare the front silver paste required for the PERC solar cell. The paste formula, calculated by mass percentage, is shown in the following table:

[0085]

[0086]

[0087] The silver powder is spherical, with a D50 of 1.8-2.2 μm and a specific surface area of 0.3-0.4 m 2 / g, bulk density is 5.5-6.0g / cm 3 , tap density is 5.5-6.0g / cm 3 .

[0088] The additive is dispersant glyceryl monooleate.

[0089] The organic carrier is ethyl cellulose, terpineol and diethylene glycol butyl ether in a weight ratio of 4:55:41.

[0090] The preparation method of the front silver paste is as follows:

[0091] The prepared composite glass powder, silver powder, organic vehicle, and additives are mixed according to the formula ratio and then mixed in a planetary mixer. The mixed premixed slurry is then thoroughly ground at least six times using a three-roll mill. The slurry particle size is controlled to ≤5μm using a scraper particle size analyzer. This produces the silver paste for the front side of PERC crystalline silicon solar cells.

[0092] The experimental pastes 1-5 prepared above were screen-printed and sintered at 760-780° C. on PERC solar cells. The electrical properties were tested, and the results are as follows.

[0093]

[0094] The electrical performance data tested above demonstrates that the front silver paste prepared using the composite glass powder exhibits an average open-circuit voltage (Voc) of 0.6880V and a fill factor of 80.30 on PERC solar cells. Furthermore, it exhibits low series resistance and high conductivity, with a maximum conversion efficiency of 22.843%. Therefore, the composite glass powder of this invention has promising future market prospects for front silver paste applications, meeting the high open-circuit voltage and high efficiency requirements of solar cell manufacturers.

Claims

1. A composite glass powder for high voltage PERC solar cell front silver paste, characterized in that: The invention comprises vanadium-phosphorus-barium system glass powder and lead-tellurium system glass powder, wherein the mass ratio of the vanadium-phosphorus-barium system glass powder to the lead-tellurium system glass powder is 1:(1.5-2.5); Wherein: by mass percentage, the vanadium phosphorus barium system glass powder composition includes 19-29% P2O5, 29-35% V2O 5、 10-23% BaO, 3-10% MnO, 1-3% Na2O, 1.5-5% K2O, 5-12% zinc sulfide, 3-10% WO3, the vanadium-phosphorus-barium system glass powder has a softening temperature of 386-458°C and a glass transition temperature of 215-350°C; Calculated by mass percentage, the lead-tellurium system glass powder comprises 18-27% PbO, 62-70.5% TeO2, 1-3% Li2O, 1-4% TiO2, and 2.5-8% P2O5. The softening temperature of the lead-tellurium system glass powder is 350-415°C, and the glass transition temperature is 200-300°C.

2. The composite glass powder for high opening voltage PERC solar cell front silver paste according to claim 1, characterized in that: 4-7μm。 The particle size distribution of the vanadium phosphorus barium system glass powder and the lead tellurium system glass powder are 0. 4-7μm.

3. A method for preparing the composite glass powder for the front silver paste of a high-opening-voltage PERC solar cell according to claim 2, comprising the following steps: (1) mixing the components of vanadium-phosphorus-barium system glass powder and lead-tellurium system glass powder respectively to obtain a mixture 1 of vanadium-phosphorus-barium system glass powder and a mixture 2 of lead-tellurium system glass powder; (2) Mixture 1 and mixture 2 are heated and melted respectively, and then quenched; (3) Drying the quenched mixture 1 and the quenched mixture 2 respectively, and then crushing them into vanadium phosphorus barium system glass powder and lead tellurium system glass powder of corresponding particle size; (4) Compounding the vanadium-phosphorus-barium system glass powder and the lead-tellurium system glass powder obtained in step (3).

4. A solar cell front silver paste, characterized in that: The raw materials for preparing the composite glass powder include the composite glass powder according to any one of claims 1-2.

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