N-type solar cell front main grid paste and N-type solar cell

Abstract

This application relates to a front busbar paste for an N-type solar cell and an N-type solar cell. The front busbar paste for an N-type solar cell comprises the following components by mass: 80% to 88% conductive metal powder, 0.4% to 3% spherical glass powder, and 10% to 19.8% organic vehicle. The spherical glass powder comprises a first spherical glass powder and a second spherical glass powder in a mass ratio of 1:(0.1 to 0.3). The first spherical glass powder is a lead-silicon-phosphorus glass composed primarily of lead, silicon, phosphorus, titanium, zinc, manganese, and copper; the second spherical glass powder is a bismuth-silicon glass composed primarily of bismuth, silicon, tellurium, zinc, and boron. The spherical glass powders have a concentrated particle size distribution and high sphericity. The busbars made with this front busbar paste exhibit higher tensile strength and aging strength, significantly reduce fork marks on silicon wafers, and achieve an additional gain of 0.1% to 0.6% in the cell's photoelectric conversion efficiency.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a front main grid paste for an N-type solar cell and an N-type solar cell. Background Art

[0002] Solar cell technology has advanced rapidly in recent years, and continuous cost reduction and efficiency improvement are crucial for the entire solar cell industry. Among the numerous solar cell technologies, N-type crystalline silicon solar cells, particularly those with a tunnel oxide passivated contact (TOPCon) structure, have gradually become a mainstream market player. This is primarily due to their advantages, such as long minority carrier lifetime and low light-induced degradation. These advantages mean that N-type TOPCon solar cells offer high power generation and strong stability.

[0003] Laser-assisted sintering (LAS), also known as laser-enhanced contact optimization (LECO), involves irradiating the cell with a high-intensity laser and applying a deflection voltage of 10V or higher. The resulting local current of several amperes significantly reduces the contact resistance between the metal and semiconductor. Combined with a specialized conductive paste, this can lead to additional efficiency gains for N-type TOPCon solar cells. However, conventional front-side busbar pastes are poorly compatible with LECO technology, resulting in low busbar tensile strength and aging resistance, numerous cross-marks on the cell, and a significant reduction in photoelectric conversion efficiency. Summary of the Invention

[0004] Based on this, it is necessary to provide an N-type solar cell front busbar paste and an N-type solar cell to overcome the poor compatibility of traditional front busbar paste with LECO technology, resulting in low busbar tension and aging tension, many cross marks on the cell, and significantly reduced photoelectric conversion efficiency.

[0005] The above-mentioned purpose of this application is achieved through the following technical solutions:

[0006] In a first aspect of the present application, a front busbar paste for an N-type solar cell is provided, comprising the following components by mass fraction: 80% to 88% of conductive metal powder, 0.4% to 3% of spherical glass powder, and 10% to 19.8% of an organic vehicle, wherein the spherical glass powder comprises a first spherical glass powder and a second spherical glass powder in a mass ratio of 1:(0.1 to 0.3); the first spherical glass powder comprises the following raw materials by mole fraction:

[0007] ;

[0008] The second spherical glass powder includes the following raw materials in molar fractions:

[0009] ;

[0010] R2O includes one or more of Li2O, Na2O and K2O;

[0011] The spherical glass powder meets the following requirements: D10 is 0.7 μm to 1.0 μm, D50 is 1.0 μm to 2.0 μm, D100 is 2.0 μm to 7.0 μm, and sphericity is ≥0.90.

[0012] In one embodiment, the first spherical glass powder further comprises one or more oxides and salt compounds of element A;

[0013] The element A includes one or more of Bi, Te, B, Mg, Al, Ca and Sb, and the total molar fraction of the oxide and salt compound of the element A in the first spherical glass powder is ≤5%.

[0014] In one embodiment, the second spherical glass powder further comprises one or more oxides and salt compounds of element B;

[0015] The B element includes one or more of Pb, Ti, Mg, Al, Ca, Ba, W, Cu, Mn and Sb, and the total molar fraction of the oxide and salt compound of the B element in the second spherical glass powder is ≤5%.

[0016] In one embodiment, the melting point of the spherical glass powder is 300°C to 400°C.

[0017] In one embodiment, the melting point of the first spherical glass powder is 300° C. to 340° C.

[0018] In one embodiment, the melting point of the second spherical glass powder is 360°C to 400°C.

[0019] In one embodiment, the method for preparing the first spherical glass powder and the method for preparing the second spherical glass powder each independently comprise the following steps:

[0020] Mixing various raw materials, performing melting treatment, and preparing molten glass;

[0021] The molten glass liquid is subjected to sheeting treatment to prepare a molding material;

[0022] The molding material is crushed to prepare granular material;

[0023] The granular material is subjected to fluidization treatment and spheroidization treatment at 400° C. to 1000° C.

[0024] In one embodiment, the melt treatment comprises the following steps: keeping the temperature at 1000°C to 1400°C for 60 minutes to 90 minutes.

[0025] In one embodiment, the flaking process comprises cold rolling flaking.

[0026] In one embodiment, the pulverization method includes one or more of mechanical crushing, air flow pulverization and ball milling.

[0027] In one embodiment, the fluidized treatment equipment includes a fluidized bed.

[0028] In one embodiment, the N-type solar cell front main grid paste further includes an inert auxiliary agent with a mass fraction of ≤0.2%, and the inert auxiliary agent includes one or more of nano-silicon, nano-silicon oxide, nano-aluminum oxide, nano-titanium dioxide and nano-tungsten trioxide.

[0029] In one embodiment, the conductive metal powder includes one or more of silver powder, copper powder, zinc powder and silver-coated aluminum powder.

[0030] In one embodiment, the organic carrier includes a resin, and the resin includes one or more of ethyl cellulose, hydroxypropyl cellulose, cellulose acetate propionate, cellulose acetate butyrate, polyvinyl formal, polyvinyl butyral, epoxy resin, phenolic epoxy resin, acrylic resin and styrene resin.

[0031] In one embodiment, the organic vehicle includes a plasticizer, and the plasticizer includes one or more of alcohol ester plasticizers, benzoate plasticizers, and phthalate plasticizers.

[0032] In one embodiment, the organic carrier includes a solvent, and the solvent includes one or more of ethanol, isopropanol, n-butanol, acetone, cyclohexanone, acetylacetone, diisobutyl ketone, ethyl propionate, ethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol butyl ether acetate, propylene glycol methyl ether acetate, dimethyl adipate and phenoxyethanol.

[0033] In a second aspect of the present application, an N-type solar cell is provided, wherein the front busbar of the N-type T solar cell is made of the above-mentioned N-type solar cell front busbar paste.

[0034] This application has at least the following beneficial effects:

[0035] The front main grid paste of the N-type solar cell provided by the present application includes spherical glass powder, which has the advantages of high sphericity and high concentration of particle size distribution, so that the weldability, tension and aging tension of the main grid are significantly improved, and the sintering window is widened, which is conducive to the preparation of the front main grid. Among the spherical glass powders, the first spherical glass powder is selected from lead silicon phosphorus glass powder, which has a strong corrosive effect on the surface of the silicon wafer, so that a good ohmic contact is formed between the main grid and the silicon wafer; P2O5 promotes the microcrystallization of the glass powder, and ZnO, MnO2 and CuO improve the adhesion between the main grid paste and the silicon wafer. Under a specific ratio, the glass transition temperature and thermal expansion coefficient of the spherical glass powder can be increased and reduced, and the strength and hardness of the spherical glass powder can be increased, thereby improving the tension and aging tension of the front main grid, and effectively suppressing the generation of cross marks. The second spherical glass powder is selected from bismuth silicon tellurium glass powder, which is used to suppress excessive corrosion of the spherical glass powder on the silicon wafer, avoid negative impact on the photoelectric conversion efficiency of the N-type solar cell, and improve weldability. Compared with traditional front main grid paste, this application utilizes spherical glass powder of specific shape and specific formula, and cooperates with conductive metal powder and organic carrier to make the front main grid paste of N-type solar cells more compatible with LECO technology. The produced main grid has higher tensile strength and aging tensile strength, and the fork mark on the cell is greatly reduced. The photoelectric conversion efficiency of the cell also has an additional gain of 0.1% to 0.6%. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application and to more fully understand the present application and its beneficial effects, the following is a brief introduction to the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present application. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0037] Figure 1 is a SEM image of the spherical glass powder in Example 1;

[0038] Figure 2 is a SEM image of the non-spherical glass powder in Comparative Example 3;

[0039] Figure 3 This is a physical picture of the battery cell prepared in Example 1;

[0040] Figure 4 This is a physical picture of the battery cell prepared in Comparative Example 3;

[0041] Figure 5 This is a physical picture of the battery cell prepared in Comparative Example 6. DETAILED DESCRIPTION

[0042] To facilitate understanding of the present application, the present application will be further described in detail below with reference to specific embodiments. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of the present application.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0044] In this application, the meaning of "and / or" includes any and all combinations of one or more related listed items. "At least one" means more than one, such as one, two and more than two. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layer" means at least two layers, such as two layers, three layers, etc., unless otherwise clearly and specifically defined. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise clearly and specifically defined.

[0045] When a numerical range is disclosed in this application, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed in this application should be understood to include any and all subranges subsumed therein.

[0046] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0047] In this application, “above” or “below” includes the number itself. For example, “1 below” includes 1.

[0048] Unless otherwise specified, the temperature parameters in this application allow for both constant temperature treatment and temperature fluctuations within a certain temperature range. It should be understood that the constant temperature treatment allows for temperature fluctuations within the accuracy range of instrument control. Fluctuations within ranges such as ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are permitted.

[0049] In this application, room temperature refers to indoor temperature, normal temperature or general temperature. Generally speaking, the range of room temperature can be any one of the following temperature intervals: 23℃±2℃, 25℃±5℃ or 20℃±5℃.

[0050] the term

[0051] Mole fraction: used to express the molar content of a component in a mixture, defined as the amount of substance n of a component i The sum of the amounts of all components in the mixture n total ratio.

[0052] Particle size distribution parameters: In a particle size distribution curve, the particle size at which the cumulative particle size distribution percentage reaches N% is called DN, indicating that particles smaller than this size account for N% of all particles, where N = 0-100. When N = 100, D100 represents the maximum particle size. When N = 50, D50 represents the median diameter or median diameter, indicating that particles smaller than this size each account for 50% and 50% respectively. For example, a D50 of 1 mm means that particles smaller than 1 mm and particles larger than 1 mm each account for 50% of all particles.

[0053] Sphericity: This is a dimensionless parameter with a value between 0 and 1 that describes how closely a particle's shape approximates a sphere. A sphericity closer to 1 indicates a particle's shape is closer to a perfect sphere; a sphericity closer to 0 indicates a particle's shape deviates further from a sphere. Sphericity can typically be calculated using the particle's volume and surface area.

[0054] In the solar cell manufacturing process, the front electrode and busbars are made of conductive paste through high-speed, high-precision screen printing, low-temperature drying, and high-temperature sintering. LECO technology, a laser-assisted sintering technology, plays a crucial role in the solar cell field. LECO technology can reduce the peak temperature of existing sintering furnaces by 20°C to 60°C, lowering the sintering temperature to 690°C to 720°C, and significantly reduce the contact resistance between metals and semiconductors. Combined with specialized conductive pastes, it can enable N-type TOPCon solar cells to achieve better open-circuit voltage, fill factor, and additional efficiency gains. However, traditional front busbar pastes are poorly compatible with LECO technology, resulting in low busbar tensile strength and aging tensile strength, numerous cross marks on the cell, and a significant reduction in photoelectric conversion efficiency.

[0055] Based on this, in a first aspect, the present application provides a front main grid paste for an N-type solar cell.

[0056] In some embodiments, the front main grid paste of an N-type solar cell includes the following components by mass fraction: 80% to 88% of conductive metal powder, 0.4% to 3% of spherical glass powder, and 10% to 19.8% of an organic vehicle, wherein the spherical glass powder includes a first spherical glass powder and a second spherical glass powder in a mass ratio of 1:(0.1 to 1);

[0057] The first spherical glass powder includes the following raw materials in mole fractions:

[0058] ;

[0059] The second spherical glass powder includes the following raw materials in mole fractions:

[0060] ;

[0061] R2O includes one or more of Li2O, Na2O and K2O;

[0062] The spherical glass powder meets the following requirements: D10 is 0.7μm~1.0μm, D50 is 1.0μm~2.0μm, D100 is 2.0μm~7.0μm, and sphericity is ≥0.90.

[0063] The front main grid paste of the N-type solar cell of the present application includes spherical glass powder, which has the advantages of high sphericity and high concentration of particle size distribution, so that the weldability, tension and aging tension of the main grid are significantly improved, and the sintering window is widened, which is beneficial to the preparation of the front main grid. Among the spherical glass powders, the first spherical glass powder is selected from lead silicon phosphorus glass powder, which has a strong corrosive effect on the surface of the silicon wafer, so that a good ohmic contact is formed between the main grid and the silicon wafer; P2O5 promotes the microcrystallization of the glass powder, and ZnO, MnO2 and CuO improve the adhesion between the main grid paste and the silicon wafer. Under a specific ratio, the glass transition temperature and thermal expansion coefficient of the spherical glass powder can be increased and reduced, and the strength and hardness of the spherical glass powder can be increased, thereby improving the tension and aging tension of the front main grid, and effectively suppressing the generation of cross marks. The second spherical glass powder is selected from bismuth silicon tellurium glass powder, which is used to suppress excessive corrosion of the spherical glass powder on the silicon wafer, avoiding negative impact on the photoelectric conversion efficiency of the N-type solar cell. Compared with traditional front main grid paste, this application utilizes spherical glass powder of specific shape and specific formula, and cooperates with conductive metal powder and organic carrier to make the front main grid paste of N-type solar cells more compatible with LECO technology. The produced main grid has higher tensile strength and aging tensile strength, and the fork mark on the cell is greatly reduced. The photoelectric conversion efficiency of the cell also has an additional gain of 0.1% to 0.6%.

[0064] The thermal expansion coefficient of traditional busbar paste during the sintering process does not match that of the solar cell, causing stress on the surface of the sintered solar cell and producing obvious cross marks in the electroluminescence (EL) test of photovoltaic modules, affecting the quality and performance of the solar cell.

[0065] In this application, the first type of glass powder is a lead-silicon-phosphorus glass composed primarily of lead, silicon, phosphorus, titanium, zinc, manganese, and copper. It has a strong corrosive effect on the silicon wafer surface, allowing for good ohmic contact between the busbar and the silicon wafer. P2O5 promotes microcrystallization of the glass melt during sintering, while ZnO, MnO2, and CuO improve the adhesion between the busbar slurry and the silicon wafer. Under specific ratios, this can effectively lower the glass transition temperature (T) of the glass powder. g ) and thermal expansion coefficient, improve the strength and hardness of the glass, thereby ensuring that the main grid has high tensile strength and aging tensile strength, and effectively suppressing the generation of fork marks.

[0066] As an example, in the first spherical glass powder, the molar fraction of PbO can be 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69% or 70%, and can be further selected from 62% to 65%; the molar fraction of SiO2 can be 21%, 21.5%, 22%, 22.5%, 23%, 23.5%, 24%, 24.5% or 25%, and can be further selected from 20% to 22%; the molar fraction of P2O5 can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, and can be further selected from 5% to 6%; the molar fraction of TiO2 can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11% , 12%, 13%, 14% or 15%, and can be further selected as 3% to 5%; the mole fraction of ZnO can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, and can be further selected as 1% to 1.5%; the mole fraction of MnO2 can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, and can be further selected as 1% to 1.5%; the mole fraction of CuO can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, and can be further selected as 1% to 1.5%; the mole fraction of RO can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%, and can be further selected as 1% to 2%.

[0067] Optionally, the first spherical glass frit further comprises one or more oxides and salt compounds of element A, wherein element A comprises one or more of Bi, Te, B, Mg, Al, Ca, and Sb. Further optionally, the first spherical glass frit comprises an oxide of element A, wherein the oxide of element A comprises one or more of Bi2O3, TeO2, B2O3, MgO, Al2O3, CaO, and Sb2O3, and further optionally MgO.

[0068] Optionally, the total molar fraction of the oxide and salt of element A in the first spherical glass frit is ≤5%. As an example, the total molar fraction of the oxide and salt of element A in the first spherical glass frit can be 0%, 1%, 2%, 3%, 4%, or 5%, and can further be 1% to 2%.

[0069] In this application, the second spherical glass frit is a bismuth-silicon glass primarily composed of bismuth, silicon, tellurium, zinc, and boron. It is used to inhibit excessive corrosion of silicon wafers by the spherical glass frit, thereby preventing negative impacts on the photoelectric conversion efficiency of N-type solar cells. Furthermore, appropriate amounts of Bi2O3 and TeO2 enhance the longitudinal corrosion and silver dissolving capabilities of the glass melt, ensuring good adhesion with conductive metal powders such as silver powder, thereby improving solderability.

[0070] As an example, in the second spherical glass powder, the molar fraction of Bi2O3 can be 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69% or 70%, and can be further selected as 66% to 68%; the molar fraction of SiO2 can be 15%, 15.5%, 16%, 16.5%, 17%, 17.5%, 18%, 18.5%, 19%, 19.5% or 20%, and can be further selected as 15% to 16%; the molar fraction of TeO2 can be 1%, 2%, The molar fraction of ZnO may be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, and may be further selected as 4% to 6%; the molar fraction of ZnO may be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, and may be further selected as 4.5% to 5.5%; the molar fraction of B2O3 may be 1%, 2%, 3%, 4%, 5%, 6%, 7% or 8%, and may be further selected as 5% to 7%; the molar fraction of R2O may be 0%, 1%, 2%, 3%, 4% or 5%, and may be further selected as 0% to 1%.

[0071] Optionally, the second spherical glass powder further comprises one or more oxides and salt compounds of element B, wherein element B comprises one or more of Pb, Ti, Mg, Al, Ca, Ba, W, Cu, Mn, and Sb. Further optionally, the second spherical glass powder comprises an oxide of element B, wherein the oxide of element B comprises one or more of PbO, TiO2, MgO, Al2O3, CaO, BaO, WO3, CuO, MnO2, and Sb2O3, and further optionally Al2O3.

[0072] Optionally, the total molar fraction of the oxide and salt of element B in the second spherical glass frit is ≤5%. As an example, the total molar fraction of the oxide and salt of element B in the second spherical glass frit can be 0%, 1%, 2%, 3%, 4%, or 5%, and can further be 1% to 2%.

[0073] As an example, R2O in the first spherical glass powder and the second spherical glass powder represents an alkali metal oxide, which can be selected from any one of Li2O, Na2O and K2O, or selected from at least two of Li2O, Na2O and K2O, and can further be selected from Na2O.

[0074] As an example, in the spherical glass powder, the mass ratio of the first spherical glass powder to the second spherical glass powder may be 1:0.1, 1:0.15, 1:0.2, 1:0.25 or 1:0.3, and may further be 1:0.2.

[0075] Optionally, the melting point of the spherical glass powder is 300° C. to 400° C. As an example, the melting point of the spherical glass powder may be 300° C., 310° C., 320° C., 330° C., 340° C., 350° C., 360° C., 370° C., 380° C., 390° C., or 400° C., and may further be 345° C. to 370° C.

[0076] Optionally, the melting point of the first spherical glass powder is 300° C. to 340° C. As an example, the melting point of the first spherical glass powder may be 300° C., 305° C., 310° C., 315° C., 320° C., 325° C., 330° C., 335° C., or 340° C., and may further be 320° C. to 330° C.

[0077] Optionally, the melting point of the second spherical glass powder is 360° C. to 400° C. As an example, the melting point of the second spherical glass powder may be 360° C., 365° C., 370° C., 375° C., 380° C., 385° C., 390° C., 395° C., or 400° C., and may further be 370° C. to 380° C.

[0078] N-type solar cells are categorized by the number of busbars: multi-busbar (MBB) and zero-busbar (0BB). 0BB differs from MBB in that the pad area and number are reduced, and a solid line connection is replaced by a series of broken points. This aims to reduce shading and wet weight, but this also makes improving the busbar's weldability and tensile strength more difficult. Using irregularly shaped glass powder with a wide particle size distribution in the busbar paste can lead to significant fluctuations in the busbar's weldability and tensile strength, narrowing the sintering window and making the front-side busbar fabrication more difficult.

[0079] The front main grid paste of the N-type solar cell provided by the present application uses spherical glass powder, which has the advantages of a narrow particle size distribution range, good particle size concentration and high sphericity. Spherical glass powder can be packed more densely, and the gaps and defects are significantly reduced, so that the sintered main grid has a higher density; the surface energy difference between the particles of the spherical glass powder is relatively small, and the contact area is relatively small and uniform, which helps to control the material transfer and grain boundary movement during the sintering process, so that the melting time and speed after heating are similar, the sintering process is more uniform and controllable, and the glass powder on the pad point after sintering is more evenly distributed, avoiding the problem of local uneven sintering. Therefore, the use of spherical glass powder significantly improves the weldability and tensile strength of the main grid, and the sintering window is widened, which helps to prepare the front main grid of N-type solar cells such as MBB and 0BB.

[0080] As an example, the D10 of the spherical glass powder can be 0.7μm, 0.75μm, 0.8μm, 0.85μm, 0.9μm, 0.95μm or 1.0μm, and can be further selected as 0.9μm~1.0μm; D50 can be 1.0μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm or 2.0μm, and can be further selected as 1.0μm~1.4μm; D100 is 2.0μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm or 7.0μm, and can be further selected as 2.0μm~3.0μm.

[0081] Optionally, the sphericity of the spherical glass powder may be 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99 or 1, and may further be 0.95 to 0.98.

[0082] Optionally, the method for preparing the first spherical glass powder and the method for preparing the second spherical glass powder each independently include the following steps:

[0083] Mixing various raw materials, performing melting treatment, and preparing molten glass;

[0084] The molten glass liquid is subjected to sheeting treatment to prepare a molding material;

[0085] The molding material is crushed to prepare granular material;

[0086] The granular material is subjected to fluidization treatment and spheroidization treatment at 400° C. to 1000° C.

[0087] As an example, the temperature of the spheroidization treatment can be 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C or 1000°C, and can further be 800°C~1000°C.

[0088] Optionally, the melt treatment includes the following steps: holding at 1000° C. to 1400° C. for 60 to 90 minutes. As an example, the melt treatment equipment includes a lifting furnace, the melt treatment temperature can be 1000° C., 1050° C., 1100° C., 1150° C., 1200° C., 1250° C., 1300° C., 1350° C., or 1400° C., and the holding time for the melt treatment can be 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, or 90 minutes.

[0089] Optionally, the flaking process comprises cold roll flaking.

[0090] Optionally, the pulverization method includes one or more of mechanical crushing, air flow pulverization and ball milling, and ball milling can be further selected.

[0091] Optionally, the ball milling method includes the following steps: placing the molding material in a planetary flip ball mill, adding a grinding aid, and ball milling at a rotation speed of 300 rpm to 600 rpm for 1 hour to 4 hours to obtain a granular material.

[0092] Optionally, the grinding aid includes water, methanol, ethanol, isopropanol, etc., and can further be ethanol.

[0093] Optionally, the mass ratio of the molding material to the grinding aid is 1:(0.5-1.5). As an example, the mass ratio of the molding material to the grinding aid can be 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5, and can further be 1:(0.9-1.1).

[0094] As an example, the ball milling speed may be 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, 550 rpm or 600 rpm, and the ball milling time may be 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h or 4 h.

[0095] Optionally, the fluidization treatment equipment includes a fluidized bed, which can fluidize the granular material and make it appear in a fluid-like state, so that the particles collide and rub against each other during movement, thereby promoting the subsequent spheroidization process.

[0096] In N-type solar cells, the main function of the front busbar is to collect carriers from the fine grid and conduct them to form current transmission. Therefore, the conductivity of the front busbar paste has a significant impact on the performance of N-type solar cells. In this application, the front busbar paste includes conductive metal powder, spherical glass powder, and an organic carrier.

[0097] As an example, in the front main grid paste of an N-type solar cell, the mass fraction of the conductive metal powder can be 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87% or 88%, and can be further selected as 82%~84%; the mass fraction of the spherical glass powder can be 0.4%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8% or 3%, and can be further selected as 1.2%~1.8%; the mass fraction of the organic carrier can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 19.8%, and can be further selected as 15%~16%.

[0098] Optionally, the N-type solar cell front main grid paste further includes an inert auxiliary agent with a mass fraction of ≤0.2%, and the inert auxiliary agent includes one or more of nano-silicon, nano-silicon oxide, nano-aluminum oxide, nano-titanium dioxide and nano-tungsten trioxide.

[0099] In the present application, the presence of the inert auxiliary agent can, to a certain extent, replace the silicon wafer to react with the spherical glass powder, thereby reducing corrosion on the silicon wafer surface and further reducing the impact on the photoelectric conversion efficiency of the battery.

[0100] As an example, the mass fraction of the inert additive in the front busbar paste of an N-type solar cell can be 0%, 0.01%, 0.02%, 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.18% or 0.2%, and can further be 0.01% to 0.05%.

[0101] As an example, the inert auxiliary agent can be selected from any one of nano-silicon, nano-silicon oxide, nano-aluminum oxide, nano-titanium dioxide, and nano-tungsten trioxide, or can be selected from at least two of nano-silicon, nano-silicon oxide, nano-aluminum oxide, nano-titanium dioxide, and nano-tungsten trioxide, and can further be nano-silicon oxide. It is understood that the inert auxiliary agent is a nanomaterial, and its average particle size can be 10 nm to 100 nm.

[0102] Optionally, the conductive metal powder includes one or more of silver powder, copper powder, zinc powder and silver-coated aluminum powder.

[0103] Optionally, the conductive metal powder is silver powder.

[0104] Optionally, the conductive metal powder includes the following components in mass fractions: 65% to 75% silver powder, 10% to 20% silver-coated aluminum powder, and 5% to 15% zinc powder, wherein the mass fraction of silver in the silver-coated aluminum powder is 40% to 60%.

[0105] The conductive metal powder in the busbar paste typically uses highly conductive silver powder, in which case the busbar paste is called silver paste. However, silver powder is expensive, which contributes to the high cost of N-type solar cells. Therefore, copper powder, zinc powder, and silver-coated aluminum powder, which are highly conductive and economical, can be used to partially replace silver powder, thereby reducing costs while maintaining efficiency. Furthermore, the morphology of the silver, copper, silver-coated aluminum, and zinc powders is not particularly limited; each can be independently selected from one or more of spherical, flaky, and amorphous shapes. Combining conductive metal powders of different shapes can increase the contact area between particles, forming a point-to-surface conductive network, further improving the conductive paste's electrical conductivity.

[0106] Optionally, the median particle size (D50) of the conductive metal powder is 0.5 μm to 2 μm. As an example, the D50 of the conductive metal powder can be 0.5 μm, 0.8 μm, 1 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, or 2 μm, and can further be 0.7 μm to 1.2 μm.

[0107] If the median particle size of the conductive metal powder is too large, it will affect the printing effect of the main grid paste, resulting in poor main grid quality and a loss of photoelectric conversion efficiency. If the median particle size of the conductive metal powder is too small, its viscosity is too low and it is not easy to accumulate. Its fluidity is too high, resulting in the width of the main grid line being too wide after printing, thereby causing a loss of photoelectric conversion efficiency. At the same time, conductive metal powder with a small particle size is more expensive and has a poor cost-effectiveness.

[0108] Optionally, the specific surface area of ​​the conductive metal powder is 0.3 m 2 / g~2m 2 As an example, the specific surface area of ​​the conductive metal powder can be 0.3m 2 / g, 0.5m 2 / g, 0.8m 2 / g、1m 2 / g, 1.2m 2 / g, 1.4m 2 / g, 1.6m 2 / g, 1.8m 2 / g and 2m 2 / g, further optional 0.5m 2 / g~1.2m 2 / g.

[0109] The specific surface area of ​​the conductive metal powder is controlled at 0.3m 2 / g~2m 2 / g range, which is also helpful to control the viscosity and fluidity of the conductive paste, so that the printing effect of the conductive paste is good, and the printed grid lines have a suitable width, thereby playing a role in ensuring the effect.

[0110] Optionally, the organic vehicle comprises a resin, and the resin comprises one or more of ethyl cellulose, hydroxypropyl cellulose, cellulose acetate propionate, cellulose acetate butyrate, polyvinyl formal, polyvinyl butyral, epoxy resin, novolac epoxy resin, acrylic resin, and styrene resin.

[0111] Optionally, the styrene resin includes one or more of styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-butylene-styrene block copolymer (SEBS) and styrene-ethylene-propylene-styrene block copolymer (SEPS), and can further be styrene-ethylene-propylene-styrene block copolymer (SEPS).

[0112] Optionally, the organic vehicle includes a plasticizer, and the plasticizer includes one or more of alcohol ester plasticizers, benzoate plasticizers, and phthalate plasticizers.

[0113] Optionally, the alcohol ester plasticizer includes one or more of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (alcohol ester dodecahydrate), diethylene glycol butyl ether acetate (butyl carbitol acetate) and 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (alcohol ester hexadecene).

[0114] Optionally, the benzoate plasticizer includes one or more of benzyl benzoate, ethylene glycol butyl ether benzoate, diethylene glycol dibenzoate, triethylene glycol dibenzoate, and dipropylene glycol dibenzoate, and may further be ethylene glycol butyl ether benzoate.

[0115] Plasticizer and solvent. Optionally, the solvent includes one or more of ethanol, isopropanol, n-butanol, acetone, cyclohexanone, acetylacetone, diisobutyl ketone, ethyl propionate, ethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol butyl ether acetate, propylene glycol methyl ether acetate, dimethyl adipate, and phenoxyethanol, and diethylene glycol butyl ether acetate may further be selected.

[0116] Optionally, in the organic vehicle, the mass ratio of the resin to the solvent is (0.5~3):(5~9):(3~8), and further optionally, the mass ratio of the resin, the plasticizer and the solvent is (1.5~2.5):(6~8):(5~7).

[0117] Optionally, the fineness of the busbar paste for the front side of an N-type solar cell is ≤6 μm. As an example, the fineness of the busbar paste for the front side of an N-type solar cell can be 0.01 μm, 0.05 μm, 0.1 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, or 6 μm.

[0118] In a second aspect of the present application, an N-type solar cell is provided, wherein a front busbar of the N-type solar cell is made of the above-mentioned N-type solar cell front busbar paste.

[0119] It is understood that the N-type solar cell can be any one of an N-type TOPCon cell, an N-type HJT cell, and an N-type IBC cell, or a combination of two thereof, such as an N-type TBC cell or an N-type HBC cell. HJT is the abbreviation for Heterojunction with Intrinsic Thin-layer, and an HJT cell refers to an intrinsic thin-film heterojunction cell; IBC is the abbreviation for Interdigitated Back Contact, and an IBC cell refers to an interdigitated back contact cell.

[0120] Optionally, the method for preparing an N-type solar cell includes the following steps:

[0121] S21: Printing the above-mentioned N-type solar cell front busbar paste on the front side of the cell, and drying at 300° C. to 400° C. to form a front busbar;

[0122] S22: Printing the front fine grid paste on the front side of the cell to form the front fine grid;

[0123] S23: performing a sintering process in a drying-sintering-annealing integrated furnace and performing a laser-assisted sintering process in a laser sintering furnace to obtain an N-type solar cell.

[0124] Optionally, the peak temperature of the sintering process is 710°C~730°C, for example, 710°C, 712°C, 714°C, 716°C, 718°C, 720°C, 722°C, 724°C, 726°C, 728°C or 730°C, and can further be 718°C~722°C.

[0125] Optionally, the sintering process is a staged sintering process, specifically comprising the following steps: sintering at 500°C-600°C for 13 seconds, sintering at 600°C-700°C for 5.1 seconds, and sintering at 700°C-730°C for 1.3 seconds.

[0126] Optionally, the laser-assisted sintering process uses a green laser with a wavelength of 500 nm to 565 nm, a deflection voltage of 19.5 V, a current of 15 A, and a power of 31 kW.

[0127] In a third aspect of the present application, a stacked battery is provided, comprising a bottom battery and a top battery;

[0128] The bottom cell is an N-type solar cell as described above;

[0129] The top cell is a perovskite solar cell.

[0130] In a fourth aspect of the present application, a photovoltaic module is provided, which includes a first packaging panel, a first packaging film, a battery string, a second packaging film and a second packaging panel stacked in sequence, and the battery string is formed by electrically connecting a plurality of N-type solar cells as described above, or by electrically connecting a plurality of stacked batteries as described above.

[0131] The following is further described in conjunction with specific examples and comparative examples. Unless otherwise specified, the raw materials involved in the following specific examples and comparative examples can be sourced from commercial sources. The instruments used can be sourced from commercial sources unless otherwise specified. The processes involved can be selected conventionally by those skilled in the art unless otherwise specified.

[0132] Example 1

[0133] (1) Preparation of spherical glass powder

[0134] Referring to Table 1, the spherical glass powder of this embodiment meets the following requirements: D10 is 0.95 μm, D50 is 1.2 μm, D100 is 2.8 μm, sphericity is 0.98, and melting point is 350°C.

[0135] The spherical glass powder consists of a first spherical glass powder and a second spherical glass powder in a mass ratio of 1:0.2;

[0136] Referring to Table 2, the melting point of the first spherical glass powder is 325° C., and the first spherical glass powder includes the following raw materials in molar fractions:

[0137] .

[0138] Referring to Table 3, the second spherical glass powder has a melting point of 375° C. and includes the following raw materials in molar fractions:

[0139] .

[0140] The preparation method of the first spherical glass powder and the second spherical glass powder is as follows: converting the molar fraction of each raw material into a mass fraction, weighing the required raw materials, and mixing them evenly in a mixer to obtain a batch material; loading the batch material into a corundum crucible, placing it in a lifting furnace, heating it to 1380°C and keeping it warm for 90 minutes, and obtaining a molten glass liquid after melting and homogenization; using a cold rolling sheeting method to perform sheeting treatment to obtain a molding material; placing the molding material in a planetary flip ball mill for ball milling, adding ethanol as a grinding aid, the mass ratio of the molding material to the grinding aid is 1:1, the ball milling speed is 500 rpm, the ball milling time is 3 hours, and drying after ball milling to obtain a granular material; using a fluidized bed to fluidize the granular material, and spheroidizing it at 900°C, quenching it after spheroidization, entering a cyclone separator through airflow for classification, and collecting it at the discharge port to obtain a spheroidized glass powder.

[0141] (2) Preparation of main grid paste for N-type solar cells

[0142] Please refer to Table 4. The main grid paste of the front side of the N-type solar cell includes the following components by mass fraction: 83% conductive metal powder, 1.2% spherical glass powder, 0.03% inert additive and 15.77% organic vehicle.

[0143] Among them, the conductive metal powder is silver powder, D50 is 0.8μm, and the specific surface area is 0.94m 2 / g.

[0144] The inert auxiliary agent is nano-silicon dioxide with an average particle size of 30nm~50nm.

[0145] The organic carrier includes styrene-ethylene-propylene-styrene block copolymer (SEPS), butyl benzoate and butyl diethylene glycol acetate in a mass ratio of 2.5:7.5:5.77.

[0146] The preparation method of the front main grid paste of the N-type solar cell comprises: placing a conductive metal powder and a spherical glass powder in a homogenizer for premixing to obtain a powder; mixing the powder with an organic carrier, stirring and centrifuging to fully mix the mixture, and then grinding the mixture in a three-roll mill for 6 times; and testing the ground fineness of the N-type solar cell front main grid paste with a scraper fineness meter to obtain a fineness of ≤6μm.

[0147] Examples 2 to 14

[0148] Referring to Tables 1 to 4, Examples 2 to 14 are substantially the same as Example 1, with the following differences:

[0149] Example 2: The particle size distribution of the spherical glass powder is: D10 is 0.85 μm, D50 is 1.2 μm, and D100 is 4.0 μm.

[0150] Example 3: The particle size distribution of the spherical glass powder is: D10 is 0.78 μm, D50 is 1.2 μm, and D100 is 6.8 μm.

[0151] Example 4: The sphericity of the spherical glass powder is 0.95.

[0152] Example 5: The sphericity of the spherical glass powder is 0.90.

[0153] Example 6: The mass ratio of the first spherical glass powder to the second spherical glass powder is 1:0.1.

[0154] Example 7: The mass ratio of the first spherical glass powder to the second spherical glass powder is 1:0.3.

[0155] Example 8: The mass ratio of the first spherical glass powder to the second spherical glass powder is 1:1.

[0156] Example 9: The formula of the first spherical glass powder is different, as follows:

[0157] The first spherical glass powder includes the following raw materials in mole fractions:

[0158] .

[0159] Example 10: The formula of the second spherical glass powder is different, as follows:

[0160] The second spherical glass powder includes the following raw materials in mole fractions:

[0161] .

[0162] Example 11: The formulas of the first spherical glass powder and the second spherical glass powder are different, as follows:

[0163] The first spherical glass powder includes the following raw materials in mole fractions:

[0164] ;

[0165] The second spherical glass powder includes the following raw materials in mole fractions:

[0166] .

[0167] Example 12: The front busbar paste of an N-type solar cell does not contain any inert additives and includes the following components by mass: 83% conductive metal powder, 1.2% spherical glass powder, and 15.8% organic vehicle.

[0168] Example 13: The content of spherical glass powder in the busbar paste of the front side of an N-type solar cell is different. The busbar paste includes the following components by mass fraction: 83% conductive metal powder, 1.5% spherical glass powder, and 15.47% organic vehicle.

[0169] Example 14: The content of spherical glass powder in the busbar paste of the front side of an N-type solar cell is different. The busbar paste includes the following components by mass fraction: 83% conductive metal powder, 1.8% spherical glass powder, and 15.17% organic vehicle.

[0170] Comparative Examples 1-10

[0171] Please refer to Tables 1 to 4. Comparative Examples 1 to 10 are basically the same as Example 1, except that the differences are as follows:

[0172] Comparative Example 1: All spherical glass powders are the first spherical glass powders.

[0173] Comparative Example 2: The amount of the second spherical glass powder in the spherical glass powder is too high, and the mass ratio of the first spherical glass powder to the second spherical glass powder is 1:0.4.

[0174] Comparative Example 3: The spherical glass powder was replaced with non-spherical glass powder.

[0175] Comparative Example 4: The particle size distribution of the spherical glass powder is: D10 is 0.68 μm, D50 is 1.2 μm, and D100 is 7.8 μm.

[0176] Comparative Example 5: The particle size distribution of the spherical glass powder is: D10 is 0.56 μm, D50 is 1.2 μm, and D100 is 8.8 μm.

[0177] Comparative Example 6: No P2O5 was added to the first spherical glass powder.

[0178] Comparative Example 7: No ZnO was added to the first spherical glass powder.

[0179] Comparative Example 8: No MnO2 was added to the first spherical glass powder.

[0180] Comparative Example 9: CuO was not added to the first spherical glass powder.

[0181] Comparative Example 10: The content of spherical glass powder in the main grid slurry of the front side of the N-type solar cell is too high.

[0182] Test Case

[0183] The N-type solar cell busbar pastes prepared in each embodiment and each comparative example were respectively printed on the front side of an N-type 210 silicon wafer, with 10,000 wafers of each paste being printed. The wafers were sintered in a drying-sintering-annealing integrated furnace at 500°C to 600°C for 13 seconds, 600°C to 700°C for 5.1 seconds, and 700°C to 730°C for 1.3 seconds, with a peak sintering temperature of 720°C. The wafers were then subjected to LECO treatment in a laser-assisted sintering furnace, with continued irradiation using a high-intensity green laser at a deflection voltage of 19.5V, a current of 15A, and a power of 31kW, to obtain solar cells.

[0184] (1) The electrical performance of the cell was tested using a HALM IV tester, and the photoelectric conversion efficiency was recorded. The results are shown in Table 5.

[0185] (2) Tensile force and aging tensile force: Fix the battery cell on the tensile testing machine through a clamp, ensure that the main grid is perpendicular to the tensile direction, and gradually increase the tensile force at a certain speed until the main grid and the battery cell are separated. The tensile force is automatically recorded by the tensile testing machine. The results are shown in Table 5. Place the battery cell in an environment of 85℃ and 85% relative humidity for 1000h, and test its aging tensile force according to the tensile test method. The results are shown in Table 5.

[0186] (3) Fork mark: Count the number of cells with fork marks among 10,000 cells and calculate the percentage of cells with fork marks. The results are shown in Table 5.

[0187] Figure 1 This is the SEM image of the spherical glass powder in Example 1, which has high sphericity, narrow particle size distribution range, and good particle size concentration. Figure 2 This is an SEM image of the non-spherical glass powder in Comparative Example 3. The glass powder is broken and irregular in shape, and has a wide particle size distribution range.

[0188] Figure 3 This is a physical picture of the battery cell prepared in Example 1. There is no cross mark on the surface of the battery cell. Figure 4 This is a physical picture of the battery cell prepared in Comparative Example 3. Figure 5 This is a physical picture of the battery cell prepared in Comparative Example 6, and there are many cross marks on the surface of the battery cell.

[0189] As shown in Table 5, the front busbars of the cell sheets of Examples 1 to 14 are made of a front busbar slurry compounded with two types of spherical glass powders. The photoelectric conversion efficiency of the cell sheets reaches 26.25% to 26.31%, the busbar tensile force reaches 2.5N to 3.3N, the aging tensile force reaches 2.3N to 2.6N, and the fork mark is only 0.01% to 0.02%.

[0190] Comparative Example 1, in which only the first spherical glass powder was added, resulted in reduced photoelectric conversion efficiency and a high number of cross marks on the cell surface. Comparative Example 2 used an excessive amount of the second spherical glass powder, Comparative Example 3 employed non-spherical glass powder, and the spherical glass powders of Comparative Examples 4 and 5 had an overly broad particle size distribution. Comparative Examples 6 to 9 omitted key components such as P2O5 from the first spherical glass powder, and Comparative Example 10 used an excessive amount of spherical glass powder. All of these factors resulted in varying degrees of degradation in performance, including photoelectric conversion efficiency, tensile strength, aging tensile strength, and cross marks.

[0191] It can be seen that the front main grid paste of the N-type solar cell provided in this application is well compatible with the LECO technology, the prepared main grid has higher tensile strength and aging tensile strength, and the fork marks on the cell are greatly reduced, and the photoelectric conversion efficiency of the cell also has an additional gain of 0.1% to 0.6%.

[0192] Table 1. Particle size, sphericity, and mass ratio of spherical glass powder

[0193]

[0194] Table 2. Formula of the first spherical glass powder

[0195]

[0196] Table 3. Formula of the second spherical glass powder

[0197]

[0198] Table 4. Formula of busbar paste for the front side of N-type solar cells

[0199]

[0200] Table 5. Performance of N-type solar cells

[0201]

[0202] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0203] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of protection of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and such modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A main grid paste for the front side of an N-type solar cell, characterized in that: The invention comprises the following components by mass fraction: 80% to 88% of conductive metal powder, 0.4% to 3% of spherical glass powder, and 10% to 19.8% of an organic vehicle, wherein the spherical glass powder comprises a first spherical glass powder and a second spherical glass powder in a mass ratio of 1:(0.1 to 0.3); The first spherical glass powder includes the following raw materials in molar fractions: ； The second spherical glass powder includes the following raw materials in molar fractions: ； R2O includes one or more of Li2O, Na2O and K2O; The spherical glass powder meets the following requirements: D10 is 0.7 μm to 1.0 μm, D50 is 1.0 μm to 2.0 μm, D100 is 2.0 μm to 7.0 μm, and sphericity is ≥0.

90.

2. The N-type solar cell front main grid paste according to claim 1, characterized in that: The first spherical glass powder further comprises one or more oxides and salt compounds of element A; The element A includes one or more of Bi, Te, B, Mg, Al, Ca and Sb, and the total molar fraction of the oxide and salt compound of the element A in the first spherical glass powder is ≤5%.

3. The N-type solar cell front main grid paste according to claim 2, characterized in that: The second spherical glass powder further comprises one or more oxides and salt compounds of element B; The B element includes one or more of Pb, Ti, Mg, Al, Ca, Ba, W, Cu, Mn and Sb, and the total molar fraction of the oxide and salt compound of the B element in the second spherical glass powder is ≤5%.

4. The N-type solar cell front main grid paste according to claim 3, characterized in that: One or more of the following conditions are met: (1) The melting point of the spherical glass powder is 300°C to 400°C; (2) The melting point of the first spherical glass powder is 300°C to 340°C; (3) The melting point of the second spherical glass powder is 360°C to 400°C.

5. The front main grid paste for an N-type solar cell according to any one of claims 1 to 4, characterized in that: The method for preparing the first spherical glass powder and the method for preparing the second spherical glass powder each independently comprise the following steps: Mixing various raw materials, performing melting treatment, and preparing molten glass; The molten glass liquid is subjected to sheeting treatment to prepare a molding material; The molding material is crushed to prepare a granular material; The granular material is subjected to fluidization treatment and spheroidization treatment at 400° C. to 1000° C.

6. The N-type solar cell front main grid paste according to claim 5, characterized in that: One or more of the following conditions are met: (1) The melt treatment comprises the following steps: keeping the temperature at 1000°C to 1400°C for 60 minutes to 90 minutes; (2) The tableting process includes cold rolling tableting; (3) The pulverization method includes one or more of mechanical crushing, air flow pulverization and ball milling; (4) The fluidized bed treatment equipment includes a fluidized bed.

7. The front main grid paste for an N-type solar cell according to any one of claims 1 to 4, characterized in that: The N-type solar cell front main grid paste further includes an inert auxiliary agent with a mass fraction of ≤0.2%, and the inert auxiliary agent includes one or more of nano-silicon, nano-silicon oxide, nano-aluminum oxide, nano-titanium dioxide and nano-tungsten trioxide.

8. The N-type solar cell front main grid paste according to claim 7, characterized in that: The conductive metal powder includes one or more of silver powder, copper powder, zinc powder and silver-coated aluminum powder.

9. The N-type solar cell front main grid paste according to claim 7, characterized in that: One or more of the following conditions are met: (1) The organic carrier comprises a resin, wherein the resin comprises one or more of ethyl cellulose, hydroxypropyl cellulose, cellulose acetate propionate, cellulose acetate butyrate, polyvinyl formal, polyvinyl butyral, epoxy resin, phenolic epoxy resin, acrylic resin and styrene resin; (2) The organic carrier includes a plasticizer, and the plasticizer includes one or more of an alcohol ester plasticizer, a benzoate plasticizer, and a phthalate plasticizer; (3) The organic carrier includes a solvent, and the solvent includes one or more of ethanol, isopropanol, n-butanol, acetone, cyclohexanone, acetylacetone, diisobutyl ketone, ethyl propionate, ethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol butyl ether acetate, propylene glycol methyl ether acetate, dimethyl adipate and phenoxyethanol.

10. An N-type solar cell, characterized in that: The front busbar of the N-type solar cell is made of the N-type solar cell front busbar slurry according to any one of claims 1 to 9.

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