An electrode paste, a preparation method thereof, and a photovoltaic cell

Abstract

The present invention discloses an electrode paste, a preparation method thereof, and a photovoltaic cell, relating to the technical field of solar cells, and aiming to solve the problem that in the process of battery manufacturing, aluminum spines in the existing electrode paste are likely to pierce through the antireflection layer and have metal surface defects, thus affecting the conversion efficiency of the battery. The electrode paste includes: a first glass material, an aluminum-based conductive material, and an organic carrier. The first glass material at least wraps the aluminum-based conductive material. The electrode paste further includes a second glass material, and at the same temperature, the viscosity of the second glass material is greater than that of the first glass material. The preparation method is used to prepare the electrode paste, and the photovoltaic cell uses the electrode paste. The electrode paste, the preparation method thereof, and the photovoltaic cell provided by the present invention are used to improve the photoelectric conversion efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and particularly relates to an electrode paste, a preparation method thereof, and a photovoltaic cell. Background Art

[0002] The utilization of solar photoelectricity is one of the fastest-growing projects in recent years. Silicon is the most ideal material for solar cells. Therefore, crystalline silicon solar cells have been developed and manufactured.

[0003] The Tunnel Oxide Passivated Contact (Topcon) cell technology has become increasingly mature and has a higher photoelectric conversion efficiency. The existing conductive paste used on the front side of Topcon cells is mainly silver-aluminum paste. When adding elemental aluminum powder in the conductive paste, "aluminum spines" are easily formed due to uneven dispersion of aluminum powder, piercing the anti-reflection film silicon nitride (SiNx) layer, which is likely to cause strong metal recombination on the silicon layer, resulting in emitter surface defects and leakage, thus affecting the conversion efficiency of the cell. Therefore, it is crucial to solve the above problems. Summary of the Invention

[0004] The purpose of the present invention is to provide an electrode paste, which reduces the possibility of aluminum spines piercing the anti-reflection layer during the cell manufacturing process, avoids the emitter surface defect problem caused by metal surface recombination, and improves the photoelectric conversion efficiency.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] An electrode paste, comprising: a first glass material, an aluminum-based conductive material, and an organic carrier. The first glass material at least wraps the aluminum-based conductive material. The electrode paste further comprises a second glass material, and the silicon mass content of the first glass material is less than the silicon mass content of the second glass material.

[0007] Compared with the prior art, on the first hand, the electrode paste provided by the present invention has the following advantages:

[0008] In the electrode paste provided by the present invention, the first glass material at least wraps the aluminum-based conductive material, so that when forming grid lines on the battery chip, under the protection of the first glass material, not only can the number of aluminum spines generated by the aluminum-based conductive material be reduced, but also the growth of aluminum spines can be slowed down or even avoided from piercing the antireflection layer (such as SiNx), thereby increasing the open-circuit voltage of the battery. At the same time, the electrode paste of the present invention also has a second glass material. The electrode paste also includes a second glass material, and the viscosity of the second glass material is greater than that of the first glass material. Therefore, when sintering the electrode paste to etch the antireflection layer (such as SiNx), at the same temperature, the viscosity of the second glass material is greater than that of the first glass material. The viscosity of the first glass material can be neutralized by the second glass material, thereby reducing the fluidity of the first glass material and slowing down the possibility of the first glass material penetrating the antireflection layer (such as SiNx), reducing the probability of defects in the emitter, and then reducing leakage.

[0009] As can be seen from the above, the electrode paste provided by the present invention can reduce the possibility of the antireflection layer (such as SiNx) being penetrated during the process of forming electrode grid lines on the battery chip, avoid the problem of emitter surface defects caused by metal surface recombination, and then reduce leakage and improve the photoelectric conversion efficiency.

[0010] In a second aspect, the present invention also provides a method for preparing an electrode paste, including:

[0011] Using the first glass material to at least wrap the aluminum-based conductive material to obtain a first blend;

[0012] Mixing at least the first blend and an organic carrier to obtain the electrode paste.

[0013] In a third aspect, the present invention also provides a photovoltaic cell. The surface of the photovoltaic cell has grid lines, and the material of the grid lines is the electrode paste provided by the present invention.

[0014] Compared with the prior art, the material of the grid lines in the photovoltaic cell provided by the present invention is the electrode paste provided by the present invention. Therefore, the beneficial effects are the same as those of the electrode paste in the first aspect and will not be elaborated here. Detailed Embodiments

[0015] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0016] In addition, the terms "first" and "second" are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more, unless otherwise specifically defined. "Several" means one or more, unless otherwise specifically defined.

[0017] An embodiment of the present invention also provides a photovoltaic cell. The surface of the photovoltaic cell has grid lines, and the material of the grid lines is the electrode paste provided by the present invention, so as to provide a photovoltaic cell with high photoelectric conversion efficiency. It should be understood that the photovoltaic cell can be a Topcon cell, a Perc cell, or other photovoltaic cells, which will not be elaborated here.

[0018] An electrode paste provided by an embodiment of the present invention includes: a first glass material, an aluminum-based conductive material, and an organic carrier. The first glass material at least wraps the aluminum-based conductive material; the electrode paste further includes a second glass material, and the viscosity of the second glass material is greater than that of the first glass material at the same temperature. It should be understood that the aluminum-based conductive material can be at least one of aluminum powder, aluminum-silicon alloy powder, or other aluminum alloy materials, which will not be limited here.

[0019] Compared with the prior art where the aluminum-based conductive material is directly added to the substrate and the aluminum-based conductive material is unevenly dispersed and prone to generating aluminum spines, and the aluminum spines will pierce through the antireflection layer (such as SiNx) when they grow up, in the electrode paste provided by the present invention, the first glass material at least wraps the aluminum-based conductive material, so that when forming grid lines on the battery chip, under the protection of the first glass material, not only the number of aluminum spines generated by the aluminum-based conductive material can be reduced, but also the growth of aluminum spines can be slowed down or even avoided from piercing through the antireflection layer (such as SiNx), thereby increasing the open-circuit voltage of the battery and improving the photoelectric conversion efficiency of the battery. The viscosity of the second glass material is greater than that of the first glass material. Therefore, when sintering the electrode paste to etch the antireflection layer (such as SiNx), the viscosity of the second glass material is greater than that of the first glass material at the same temperature, and the viscosity of the second glass material can be used to neutralize the viscosity of the first glass material, thereby reducing the fluidity of the first glass material of the electrode, slowing down the possibility of the first glass material penetrating through the antireflection layer (such as SiNx), reducing the probability of defects in the emitter, and then reducing the leakage current.

[0020] The mass ratio of the first glass material to the aluminum-based conductive material in the embodiment of the present invention is (3-8):1. At this mass ratio, after melting the first glass material, the first glass material can evenly wrap the aluminum-based conductive material.

[0021] The electrode paste of the embodiment of the present invention further includes a second glass material, and the silicon mass content contained in the first glass material is less than the silicon mass content contained in the second glass material. It should be understood that since the silicon mass content in the glass material determines the softening point of the glass, the greater the silicon mass content, the higher the softening point of the glass, and therefore the softening point of the second glass material is greater than the softening point of the first glass material.

[0022] In an achievable manner, in the electrode slurry implemented by the present invention, the mass ratio of the first glass material to the second glass material is (1-5): (0.1-2). Wherein, the first glass material and the second glass material both contain silicon dioxide, the first glass material contains silicon dioxide at a molar percentage of 0% to 15%, and the second glass material contains silicon at a molar percentage of 25% to 35%. And / or, the first glass material further contains aluminum oxide, the first glass material contains aluminum oxide at a molar percentage of 1% to 3%, and the second glass material contains silver oxide, the second glass material contains silver oxide at a molar percentage of 1% to 5%.

[0023] Exemplarily, when etching the anti-reflection layer (such as SiNx) by sintering the electrode paste, since the softening point of the second glass material is greater than the softening point of the first glass material, the viscosity of the second glass material is greater than the viscosity of the first glass material. At this time, the interaction between the first glass material and the second glass material is observed under a microscope. When the first glass material and the second glass material begin to have an interaction, the second glass material can slow down the flow rate of the first glass material, thereby slowing down the doping rate of the first glass material, resulting in a weakening of the ability of heavy metallization doping. The aluminum oxide contained in the first glass material can increase the viscosity of the glass liquid and not only slow down the softening rate, but also slow down the possibility of the first glass material penetrating the anti-reflection layer (such as SiNx) because the slower the doping rate, the lower the doping concentration, which can reduce the possibility of the first glass material penetrating the anti-reflection layer (such as SiNx), reduce the probability of emitter defects, and then reduce leakage. The silver oxide contained in the second glass material in this embodiment can change the color of the glass as a colorant.

[0024] In one example, the electrode paste of the present invention comprises, by mole percentage, 25% to 65% of PbO, 10% to 25% of B 2 O 3 , 1% to 25% ZnO and 0% to 25% of the first oxide. In terms of molar percentage, the second glass material includes 15 to 30% TeO 2 , 5~8% Bi 2 O 3 , 15% to 30% PbO, 25% to 35% SiO 2 , 3% to 8% ZnO, 1% to 10% WO 3 1% to 5% Ag 2O and 0.1% to 10% of a second oxide. The first oxide and / or the second oxide contains at least one of an alkali metal oxide, an alkali metal carbonate, and an alkali metal halide.

[0025] In an alternative embodiment, in the electrode paste of the present invention, the particle size ranges of the first glass material and the second glass material are from 0.5 μm to 5 μm, and the particle size range of the aluminum-based conductive material is from 0.5 μm to 5 μm. The aluminum-based conductive material includes at least one of aluminum and aluminum alloy; the aluminum alloy includes at least one of aluminum-silicon alloy and aluminum-lead alloy.

[0026] Exemplarily, the electrode paste of the present invention further contains a silver-based conductive material, and the particle size range of the silver-based conductive material is from 0.5 μm to 3.5 μm; the mass ratio of the silver-based conductive material, the aluminum-based conductive material, and the organic carrier is (80 - 90):(1 - 10):(5 - 15).

[0027] For the silver-based conductive material, it can be any one or two of silver powder, Ag-M alloy powder, and Ag-Cu-N alloy powder, where M includes one or more of Al, Au, Ba, Bi, Ca, Cd, Ce, Co, Cr, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Ho, In, Ir, La, Lu, Mg, Mn, Mo, Nd, Ni, Pb, Pd, Pm, Pr, Pt, Re, Rh, Ru, Sb, Sc, Si, Sm, Sn, Sr, Tb, Te, Ti, Tm, Y, Yb, Zn, Zr; where N includes one or more of P, Zn, Ni, Pb, Sn.

[0028] For the organic carrier, it includes a resin, a solvent, a surface dispersant, and a thixotropic agent. The resin includes one or more of ethyl cellulose, cellulose acetate butyrate, rosin resin, acrylic resin, and polyvinyl butyral. The solvent includes one or more of terpineol, butyl carbitol, butyl carbitol acetate, diethylene glycol dibutyl ether, tripropylene glycol monomethyl ether, triethylene glycol butyl ether, alcohol ester 12, and alcohol ester 16. The surface dispersant includes one or more of stearic acid, stearic acid derivatives, unsaturated fatty acids, or alkyl amines. The thixotropic agent includes one or more of modified hydrogenated castor oil and polyamide wax.

[0029] The present invention also provides a method for preparing the electrode paste, which includes:

[0030] Step 101: Wrap the aluminum-based conductive material with the first glass material at least to obtain a first blend. For example, the raw materials of the first glass material can be placed in a three-dimensional mixer and mixed evenly, and the evenly mixed first glass material can be placed in an alumina crucible for melting. The aluminum-based conductive material is added to the melted first glass material so that the first glass material evenly wraps the aluminum-based conductive material to obtain a first blend. Since the first glass material can evenly wrap the aluminum-based conductive material in a molten state, under the protection of the first glass material, not only can the number of aluminum spines generated by the aluminum-based conductive material be reduced, but also the growth of aluminum spines can be slowed down or even avoided from piercing the antireflection layer (such as SiNx), thereby increasing the open-circuit voltage of the battery.

[0031] Step 102: Mix at least the first blend and the organic carrier to obtain an electrode paste. For example, the first blend and the silver-based conductive material are added to the organic carrier and stirred for 2 hours, and then the stirred mixture is rolled on a three-roll mill 6 times for further dispersion and homogenization. When the fineness of the scraper of the three-roll mill is less than 10 μm, it is filtered with a 400-mesh filter cloth to obtain an electrode paste. Due to the different softening points of the first glass material and the second glass material, and the viscosity of the second glass material being greater than that of the first glass material, the electrode paste prepared according to the technical solution of the present invention can reduce the fluidity of the first glass material, slow down the possibility of the first glass material penetrating the antireflection layer (such as SiNx), reduce the probability of defects in the emitter, thereby reducing leakage and increasing the open-circuit voltage. The greater the open-circuit voltage, the higher the photoelectric conversion efficiency.

[0032] Exemplarily, the preparation method of the above organic carrier can be: Weigh the solvent by mass percentage, and mix 32% butyl carbitol acetate, 14% diethylene glycol dibutyl ether, 25% tripropylene glycol monomethyl ether, and 5% alcohol ester hexadecane evenly to obtain a mixed solvent; then weigh 8.5% ethyl cellulose resin, 6.2% acrylic resin, and 4.8% polyvinyl butyral ester, and add them to the mixed solvent; then add 2.5% stearic acid dispersant and 2% polyamide wax thixotropic agent, and then heat to 80 °C while stirring. After the resin is completely dissolved, continue to stir for 60 minutes, and then cool to room temperature to obtain the organic carrier.

[0033] In an optional manner, the first glass material is used to at least wrap the aluminum-based conductive material to obtain a first blend, including: adding the aluminum-based conductive material to the raw material of the first glass material in a molten state to obtain a molten mixture, wherein the temperature of the molten state is less than the melting point of the aluminum-based conductive material. The molten mixture is processed into a first blend, and the first blend is a powdered mixture. For example: the first glass material is rolled into sheets using a rolling mill, and the rolled glass sheets are crushed using a pulverizer, and then the crushed glass powder is screened using a vibration screening machine, and then the screened glass powder is polished, ground and graded using an airflow mill. Among them, the rolling mill can be a double-roll rolling mill or a single-roll rolling mill, the pulverizer can be any one of a mechanical pulverizer, an airflow pulverizer, a grinder and a low-temperature pulverizer, the vibration screening machine can be a fixed screening machine or a movable screening machine, and the airflow flattening can be a flat airflow mill, a circulating airflow mill, a jet airflow mill, a target airflow mill, and a fluidized jet airflow mill.

[0034] Exemplarily, the preparation method of the second glass material may be: placing the raw materials of the second glass material in a three-dimensional mixer and mixing them uniformly, placing the uniformly mixed second glass material in an alumina crucible and melting it to obtain the second glass material, and processing the second glass material into a powder. The processing method of processing the second glass material into a powder is the same as the above-mentioned method of processing the first blend into a powder, and will not be repeated here.

[0035] Exemplarily, the temperature of the molten state of the first glass material is lower than the melting point of the aluminum-based conductive material, and before the aluminum-based conductive material is added to the raw material of the molten first glass material to obtain the molten mixture, the method for preparing the electrode slurry further includes: heating the raw material of the first glass material to 1000° C. to 1100° C., melting the raw material of the first glass material at 1000° C. to 1100° C. for 60 min to 70 min, and cooling to 500° C. to 600° C. At this time, the first glass material can evenly wrap the aluminum-based conductive material in the molten state.

[0036] On this basis, the electrode slurry also includes a second glass powder, and at least the first blend and the organic carrier are mixed. Before obtaining the electrode slurry, the method also includes: making the second glass powder, the first blend and the organic carrier into the electrode slurry. Since the viscosity of the second glass material is greater than the viscosity of the first glass material, when the electrode slurry is sintered to etch the anti-reflection layer (such as SiNx), the second glass material can be used to neutralize the viscosity of the first glass material, thereby reducing the fluidity of the first glass material, slowing down the possibility of the first glass material penetrating the anti-reflection layer (such as SiNx), reducing the probability of defects in the emitter, and then reducing leakage and improving the photoelectric conversion efficiency.

[0037] To verify the effectiveness of the electrode paste provided by the embodiments of the present invention, the embodiments of the present invention are proven by comparing examples with comparative examples.

[0038] Example 1

[0039] The embodiments of the present invention provide an electrode paste, including: a first glass material, an aluminum-based conductive material, and an organic carrier, and the first glass material at least wraps the aluminum-based conductive material. Table 1 shows the proportioning table of the components of the glass material in Example 1 of the present invention in terms of molar percentage, and Table 2 shows the proportioning table of the components of the electrode paste in Example 1 of the present invention in terms of mass percentage.

[0040] Table 1 Proportioning table of the components of the glass material in Example 1 in terms of molar percentage

[0041]

[0042] Table 2 Proportioning table of the components of the electrode paste in Example 1 in terms of mass percentage

[0043]

[0044] The preparation method of the electrode paste provided in Example 1 of the present invention includes the following steps:

[0045] First step, wrap the aluminum-based conductive material with a molar percentage of 5% with a first glass material with a molar percentage of silicon in a molten state of 12% to obtain a molten mixture, and process the molten mixture into a powdery first blend.

[0046] Second step, mix the first blend with a second glass material with a molar percentage of silicon of 30%, a silver-based conductive material, and an organic carrier in a ratio of 1.5:0.5:87:11 by mass percentage, and roll and filter using a three-roll mill to obtain the electrode paste.

[0047] Example 2

[0048] The embodiments of the present invention provide an electrode paste, including: a first glass material, an aluminum-based conductive material, and an organic carrier, and the first glass material at least wraps the aluminum-based conductive material. Table 3 shows the proportioning table of the components of the glass material in Example 2 of the present invention in terms of molar percentage, and Table 4 shows the proportioning table of the components of the electrode paste in Example 2 of the present invention in terms of mass percentage.

[0049] Table 3 Proportioning table of the components of the glass material in Example 2 in terms of molar percentage

[0050]

[0051] Table 4 Proportioning table of the components of the electrode paste in Example 2 in terms of mass percentage

[0052]

[0053] The preparation method of the electrode paste provided in the second embodiment of the present invention includes the following steps:

[0054] In the first step, a first glass material with a silicon molar percentage of 12% in a molten state is used to wrap an aluminum-based conductive material with a molar percentage of 5% to obtain a molten mixture, and the molten mixture is processed into a powdery first blend.

[0055] In the second step, the first blend is mixed with a second glass material with a silicon molar percentage of 24%, a silver-based conductive material, and an organic carrier in a mass percentage ratio of 1.3:0.7:87:11, and after rolling with a three-roll mill and filtering, an electrode paste is obtained.

[0056] Example 3

[0057] The present invention provides an electrode paste in an embodiment, including: a first glass material, an aluminum-based conductive material, and an organic carrier, and the first glass material at least wraps the aluminum-based conductive material. Table 5 shows the component ratio table of the glass material in the third embodiment of the present invention in terms of molar percentage, and Table 6 shows the component ratio table of the electrode paste in the third embodiment of the present invention in terms of mass percentage.

[0058] Table 5 Component ratio table of the glass material in Example 3 in terms of molar percentage

[0059]

[0060] Table 6 Component ratio table of the electrode paste in Example 3 in terms of mass percentage

[0061]

[0062] The preparation method of the electrode paste provided in the third embodiment of the present invention includes the following steps:

[0063] In the first step, a first glass material with a silicon molar percentage of 12% in a molten state is used to wrap an aluminum-based conductive material with a molar percentage of 4% to obtain a molten mixture, and the molten mixture is processed into a powdery first blend.

[0064] In the second step, the first blend is mixed with a second glass material with a silicon molar percentage of 24%, a silver-based conductive material, and an organic carrier in a mass percentage ratio of 1.7:0.3:87:11, and after rolling with a three-roll mill and filtering, an electrode paste is obtained.

[0065] Example 4

[0066] An embodiment of the present invention provides an electrode paste, comprising: a first glass material, an aluminum-based conductive material, and an organic carrier, wherein the first glass material at least wraps the aluminum-based conductive material. Table 7 shows the proportioning table of the components of the glass material in Embodiment 4 of the present invention in terms of molar percentage, and Table 8 shows the proportioning table of the components of the electrode paste in Embodiment 4 of the present invention in terms of mass percentage.

[0067] Table 7 Proportioning Table of the Components of the Glass Material in Embodiment 4 in Terms of Molar Percentage

[0068]

[0069] Table 8 Proportioning Table of the Components of the Electrode Paste in Embodiment 4 in Terms of Mass Percentage

[0070]

[0071] The preparation method of the electrode paste provided in Embodiment 4 of the present invention comprises the following steps:

[0072] First step, wrap the aluminum-based conductive material with a molar percentage of 8% using a first glass material with a molar percentage of silicon in a molten state of 8% to obtain a molten mixture, and process the molten mixture into a powdery first blend.

[0073] Second step, mix the first blend with a second glass material with a molar percentage of silicon of 11%, a silver-based conductive material, and an organic carrier in a ratio of 1.8:0.2:87:11 by mass percentage, and roll and filter using a three-roll mill to obtain the electrode paste.

[0074] Embodiment 5

[0075] An embodiment of the present invention provides an electrode paste, comprising: a first glass material, an aluminum-based conductive material, and an organic carrier, wherein the first glass material at least wraps the aluminum-based conductive material. Table 9 shows the proportioning table of the components of the glass material in Embodiment 5 of the present invention in terms of molar percentage, and Table 10 shows the proportioning table of the components of the electrode paste in Embodiment 5 of the present invention in terms of mass percentage.

[0076] Table 9 Proportioning Table of the Components of the Glass Material in Embodiment 5 in Terms of Molar Percentage

[0077]

[0078] Table 10 Proportioning Table of the Components of the Electrode Paste in Embodiment 5 in Terms of Mass Percentage

[0079]

[0080] The preparation method of the electrode paste provided in Embodiment 5 of the present invention comprises the following steps:

[0081] In the first step, an aluminum-based conductive material with a molar percentage of 6% is wrapped with a first glass material having a molar percentage of silicon in a molten state of 8% to obtain a molten mixture, and the molten mixture is processed into a powdery first blend.

[0082] In the second step, the first blend is mixed with a second glass material having a molar percentage of silicon of 24%, a silver-based conductive material, and an organic carrier in a mass percentage ratio of 1.2:0.8:87:11, and after rolling with a three-roll mill and filtering, an electrode paste is obtained.

[0083] Example Six

[0084] An electrode paste provided by an embodiment of the present invention includes: a first glass material, an aluminum-based conductive material, and an organic carrier, and the first glass material at least wraps the aluminum-based conductive material. Table 11 shows the proportion table of the components of the glass material in Example Six of the present invention in terms of molar percentage, and Table 12 shows the proportion table of the components of the electrode paste in Example Six of the present invention in terms of mass percentage.

[0085] Table 11 Proportion Table of the Components of the Glass Material in Example Six in Terms of Molar Percentage

[0086]

[0087] Table 12 Proportion Table of the Components of the Electrode Paste in Example Six in Terms of Mass Percentage

[0088]

[0089] The preparation method of the electrode paste provided by Example Six of the present invention includes the following steps:

[0090] In the first step, an aluminum-based conductive material with a molar percentage of 5% is wrapped with a first glass material having a molar percentage of silicon in a molten state of 12% to obtain a molten mixture, and the molten mixture is processed into a powdery first blend.

[0091] In the second step, the first blend is mixed with a second glass material having a molar percentage of silicon of 30%, a silver-based conductive material, and an organic carrier in a mass percentage ratio of 2.2:1.2:86.4:10.2, and after rolling with a three-roll mill and filtering, an electrode paste is obtained.

[0092] Example Seven

[0093] The preparation method of the electrode paste provided by Example Seven of the present invention is the same as that of Example 1, except that the solvent used in preparing the organic carrier is a single tripropylene glycol monomethyl ether.

[0094] Example Eight

[0095] The preparation method of the electrode paste provided in the eighth embodiment of the present invention is the same as that in Embodiment 1, except that the resin used in preparing the organic carrier is a single ethyl cellulose resin.

[0096] Comparative Example 1

[0097] In Comparative Example 1 of the present invention, a commercially available Topcon silver-aluminum paste is used as the comparative electrode paste, and the glass powder used is Pb-Si-B series glass. Table 13 shows the proportioning table of the components of the electrode paste in Comparative Example 1 of the present invention by mass percentage.

[0098] Table 13 Proportioning table of the components of the electrode paste in Comparative Example 1 by mass percentage

[0099]

[0100] The preparation method of the electrode paste provided in Comparative Example 1 of the present invention includes the following steps:

[0101] In the first step, a molten mixture is obtained by wrapping an aluminum-based conductive material with a molar percentage of 5% with molten glass powder, and the molten mixture is processed into a powdery first blend.

[0102] In the second step, the first blend, the silver-based conductive material, and the organic carrier are mixed in a ratio of 2:87:11 by mass percentage, and after rolling with a three-roll mill and filtering, an electrode paste is obtained.

[0103] Comparative Example 2

[0104] The electrode paste used in Comparative Example 2 of the present invention includes: a first glass material, an aluminum-based conductive material, and an organic carrier, and the first glass material at least wraps the aluminum-based conductive material. Table 14 shows the proportioning table of the components of the glass material in Comparative Example 2 of the present invention by molar percentage, and Table 15 shows the proportioning table of the components of the electrode paste in Comparative Example 2 of the present invention by mass percentage.

[0105] Table 14 Proportioning table of the components of the glass material in Comparative Example 2 by molar percentage

[0106]

[0107] Table 15 Proportioning table of the components of the electrode paste in Comparative Example 2 by mass percentage

[0108]

[0109] The preparation method of the electrode paste provided in Comparative Example 2 of the present invention includes the following steps:

[0110] First step: Wrap the aluminum-based conductive material with a molar percentage of 5% using molten glass powder to obtain a molten mixture, and process the molten mixture into a powdery first blend.

[0111] Second step: Mix the first blend with the silver-based conductive material and the organic carrier in a mass percentage ratio of 2:87:11, roll it using a three-roll mill and then filter to obtain the electrode paste.

[0112] The present invention tests the performance of the electrode pastes prepared in the examples and comparative examples. First, using Topcon silicon wafers with the same sheet resistance, screen-print the prepared electrode paste and the same main grid silver paste on the front and back fine grids and the front and back main grids of the battery respectively. The same electrode paste is used for a single print on the back. After drying - sintering - cooling to room temperature, Topcon solar cells are obtained. Secondly, use an IV tester to perform IV electrical performance tests on the TOPCon solar cells. The test results of the examples and comparative examples are as follows in the table:

[0113]

[0114] As can be seen from the above table, for the electrode pastes prepared in Examples 1 to 6, the solar cells prepared by screen printing have a higher open-circuit voltage and a higher photoelectric conversion efficiency compared to Comparative Example 1 and Comparative Example 2. In Examples 7 and 8, a single solvent or a single resin is used, and the open-circuit voltage and the photoelectric conversion efficiency of the solar cells are lower than those in Examples 1 to 6, but still greater than those in Comparative Example 1 and Comparative Example 2.

[0115] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claimed rights.

Claims

1. An electrode paste, characterized in that, it comprises: a first glass material, an aluminum-based conductive material, and an organic carrier, wherein the first glass material at least wraps the aluminum-based conductive material; the electrode paste further comprises a second glass material, and at the same temperature, the viscosity of the second glass material is greater than that of the first glass material; the mass content of silicon in the first glass material is less than the mass content of silicon in the second glass material, and the mass ratio of the first glass material to the second glass material is (1-5):(0.1-2); wherein, both the first glass material and the second glass material contain silicon dioxide, the molar percentage of silicon dioxide in the first glass material is 0%-15%, and the molar percentage of silicon in the second glass material is 25%-35%; the first glass material further contains aluminum oxide, the molar percentage of aluminum oxide in the first glass material is 1%-3%, the second glass material contains silver oxide, and the molar percentage of silver oxide in the second glass material is 1%-5%.

2. The electrode paste according to claim 1, characterized in that, the mass ratio of the first glass material to the aluminum-based conductive material is (3-8):

1.

3. The electrode paste according to claim 1, characterized in that, By molar percentage, the first glass material further comprises 25% to 65% of PbO, 10% to 25% of B 2 O 3 , 1% to 25% of ZnO and 0% to 25% of a first oxide; The second glass material comprises 15 to 30% of TeO by mole percentage 2 , 5 to 8% of Bi 2 O 3 , 15% to 30% of PbO, 25% to 35% of SiO 2 , 3% to 8% of ZnO, 1% to 10% of WO 3 , 1% to 5% of Ag 2 O and 0.1% to 10% of a second oxide; the first oxide and / or the second oxide contains at least one of alkali metal oxides, alkali metal carbonates, and alkali metal halides.

4. The electrode paste according to claim 1, characterized in that, the particle size ranges of the first glass material and the second glass material are 0.5μm-5μm, and the particle size range of the aluminum-based conductive material is 0.5μm-5μm; the aluminum-based conductive material comprises at least one of aluminum and aluminum alloy; the aluminum alloy comprises at least one of aluminum-silicon alloy and aluminum-lead alloy.

5. The electrode paste according to claim 1, characterized in that, the electrode paste further contains a silver-based conductive material, and the particle size range of the silver-based conductive material is 0.5μm-3.5μm; the mass ratio of the silver-based conductive material, the aluminum-based conductive material, and the organic carrier is (80-90):(1-10):(5-15).

6. A preparation method of the electrode paste according to any one of claims 1-5, characterized in that, it comprises: using the first glass material to at least wrap the aluminum-based conductive material to obtain a first blend; mixing the second glass powder, the first blend, and the organic carrier to prepare the electrode paste.

7. The preparation method of the electrode paste according to claim 6, characterized in that, the using the first glass material to at least wrap the aluminum-based conductive material to obtain a first blend includes: adding the aluminum-based conductive material to the raw materials of the first glass material in a molten state to obtain a molten mixture, and the temperature of the molten state is lower than the melting point of the aluminum-based conductive material; processing the molten mixture into a first blend, and the first blend is a powdery mixture.

8. The preparation method of the electrode paste according to claim 7, characterized in that, The temperature of the molten state is lower than the melting point of the aluminum-based conductive material. Before adding the aluminum-based conductive material to the raw materials of the first glass material in the molten state to obtain a molten mixture, the method for preparing the electrode paste further includes: Heating the raw materials of the first glass material to 1000°C to 1100°C, melting the raw materials of the first glass material at 1000°C to 1100°C for 60 minutes to 70 minutes, and cooling down to 500°C to 600°C.

9. A photovoltaic cell, Characterized in that, The surface of the photovoltaic cell has grid lines, and the material of the grid lines is the electrode paste according to any one of claims 1 to 5.

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