A main grid silver paste for silicon solar cells and a preparation method thereof

Abstract

The application provides a kind of main grid silver paste for silicon solar cell and a preparation method thereof.The main grid silver paste for silicon solar cell has good secondary grid matching ability and high main grid line peeling strength, and comprises silver powder, glass powder and organic carrier, wherein the weight percentage of each component is as follows, based on the total weight of the main grid silver paste for silicon solar cell being 100%: silver powder 80.0%-90.0%; glass powder 0.3%-2.0%; and organic carrier 8.0%-15.0%.The main grid silver paste for silicon solar cell provided by the application can better match the step-by-step printing of different types of cell pieces, and can also match different types of secondary grid silver paste, with high open voltage after matching, high photoelectric conversion efficiency, and high main grid peeling strength, which can better meet the requirements of the current different types of paste and cell piece step-by-step printing main grid paste.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of silicon solar cells, and particularly relates to a main grid conductive silver paste for silicon solar cells and a preparation method of the main grid conductive silver paste for silicon solar cells. TECHNICAL BACKGROUND

[0002] Crystalline silicon solar cells are silicon-based semiconductor devices that convert light energy into electrical energy by using the photoelectric effect of semiconductors. According to the type of silicon crystal and the characteristics of the PN junction, crystalline silicon solar cells can be divided into P-type polycrystalline silicon cells, P-type monocrystalline silicon cells, P-type Perc monocrystalline silicon cells, P-type Se-Perc monocrystalline silicon cells, and N-type polycrystalline silicon cells, N-type monocrystalline cells, and N-type topcon cells. From the current development status, the mainstream is P-type Se-Perc monocrystalline silicon cells and N-type topcon cells, and the more mature one among them is P-type Se-Perc monocrystalline silicon cells, and the one with more development potential is N-type topcon cells. Both of them are the mainstream of the development of silicon solar cells in recent years.

[0003] Market demand is the most important factor in determining the development direction of the product, no matter what kind of silicon solar cell, the final realization of high photoelectric conversion efficiency and long service life is the goal of the practical application of silicon solar cell, which also promotes the development of silicon solar cell silver paste to high opening pressure, low contact resistance, high glass strength of the main grid grid line. The conductive silver paste of silicon solar cell is generally composed of silver powder, glass powder and organic carrier, the organic carrier mainly plays the role of ensuring the screen printing effect of silver paste, after the printing of silver paste is completed, the silver powder and glass powder are responsible for building the complete grid electrode on the surface of the cell, the silver powder mainly plays the role of forming the channel of electron collection and electron export, the glass powder mainly plays the role of helping to sinter the silver powder, etching the insulating anti-reflection film on the surface of the cell and forming the contact channel between PN junction and silver grid, therefore, even if the content of glass in the silicon solar cell silver paste is very small, its role is extremely important, which directly affects the photoelectric conversion efficiency of the cell after printing the grid electrode and the glass strength of the main grid grid line. However, with the development of silicon solar cell technology, it is found that a single silver paste is difficult to balance high efficiency and high glass strength of the main grid grid line, thus a new cell silver paste printing method is developed, that is, the printing method of printing the main grid grid line on the surface of the cell first and then completing the printing of the secondary grid line, two different pastes are selected to be printed on the surface of the silicon solar cell by step printing, so that the photoelectric conversion efficiency of the cell and the glass strength of the grid line are balanced, thus the silicon solar cell main grid silver paste is born. Since the silicon solar cell main grid silver paste was born, the step printing method of main and secondary grid silver paste has become the mainstream, at least 80% of the customers have adopted the silicon solar cell grid line printing method of main and secondary grid silver paste, therefore, it has important practical application value and economic value to develop a main grid silver paste with excellent performance. According to the function and application characteristics of the main grid silver paste, a silicon solar cell main grid silver paste with excellent performance should have high main grid peel strength and excellent electrical performance, and can be widely matched with different secondary grid silver pastes. SUMMARY

[0004] The present application provides a kind of main grid silver paste for silicon solar cell, it can be well matched with the main grid of different types of cell piece, and can be widely matched with the characteristics of different kinds of secondary grid silver paste, with high opening pressure, high photoelectric conversion efficiency, high main grid peel strength.

[0005] The present application is realized as follows: a kind of main grid conductive silver paste for silicon solar cell, it contains silver powder, glass powder and organic carrier, and the weight percentage of each component is as follows, based on the total weight of the main grid silver paste for silicon solar cell being 100%:

[0006] Silver powder 80.0%~90.0%;

[0007] Glass powder 0.3%~2.0%;

[0008] Organic carrier 10.0%~20.0%.

[0009] The silver powder is composed of two different particle size silver powders, and the glass powder is a main glass powder, which can be matched with an auxiliary glass powder.

[0010] The silver powder is composed of two different particle size silver powders, and the glass powder is a main glass powder, which can be matched with an auxiliary glass powder.

[0011] The first silver powder 90.0%~95.0%;

[0012] The second silver powder 5.0%~10.0%;

[0013] The glass powder for the main grid silver paste of the silicon solar cell comprises a main glass powder and an auxiliary glass powder, and the auxiliary glass powder can be selected to be added or not. The particle size distribution of the main glass powder and the auxiliary glass powder is between 0.3~3.0μm, D50 is not greater than 1.0μm, and D90 is not greater than 1.5μm. The weight composition ratio of the main glass powder and the auxiliary glass powder is, for example, as follows:

[0014] The main glass powder 60.0%~100.0%;

[0015] The auxiliary glass powder 0.0%~40.0%.

[0016] The main glass powder is a Pb-Ti-B-Si-O element main structure glass with the addition of other element substances. The molar composition ratio of each substance contained in the main glass powder is, for example, as follows:

[0017] PbO 25.0%~45.0%;

[0018] TiO2 5.0%~20.0%;

[0019] B2O3 5.0%~15.0%;

[0020] SiO2 20.0%~45.0%;

[0021] Other element substances 0.0%~20.0%.

[0022] The Pb-Ti-B-Si-O main glass powder for the silicon solar cell main grid silver paste further comprises some modified additive substances, which are one or more of substances containing Te, Al, Cu, Zn, Ca, Mg, Tl, W, Ge, Bi, Mn, Cr, and Sb elements.

[0023] The auxiliary glass powder is a Pb-Te-Bi-Zn-Si-O element main structure glass containing some other element substances, and the molar composition ratio of each substance contained in the auxiliary glass powder is, based on the molar percentage content of the auxiliary glass powder component being 100%, as follows:

[0024] PbO 30.0%~45.0%;

[0025] TeO2 30.0%~45.0%;

[0026] Bi2O3 5.0%~10.0%;

[0027] SiO2 0.0%~10.0%;

[0028] ZnO 2.5%~10.0%;

[0029] Other element substances 0.0%~15.0%.

[0030] The Pb-Te-Bi-Zn-Si-O element main structure auxiliary glass powder for the silicon solar cell main grid silver paste further comprises some modified additive substances, which are one or more of substances containing Al, B, Cu, Mg, Tl, W, and Ge elements.

[0031] The raw material for preparing the main glass powder or the auxiliary glass powder for the silicon solar cell main grid silver paste is an oxide of the raw material or a substance that can be decomposed to obtain the oxide or a compound that can be decomposed to obtain the oxide formed by the elements in the glass composition.

[0032] The organic carrier for the silicon solar cell main grid silver paste comprises an organic solvent, an organic resin, and a defoaming agent, and the content of each component is, based on the total weight of the organic carrier being 100%, as follows:

[0033] Organic solvent 70.0%~90.0%;

[0034] Organic resin 5.0%~20.0%;

[0035] Defoaming agent 5.0%~20.0%.

[0036] The application further provides a preparation method of the main grid silver paste for the silicon solar cell, and the method comprises the following steps:

[0037] Preparation of glass powder: the raw materials are weighed according to the designed glass powder composition, then mixed uniformly, added into a crucible, and then placed in a muffle furnace at 1000-1300 DEG C for 20-60 min, then taken out after the raw materials are completely melted and homogenized, poured into cooling water for cooling, then filtered out glass particles, dried at 100-130 DEG C, cooled to room temperature, then added into a disc mill to crush into primary glass powder at a disc gap of 50-200 microns, and finally ground into glass powder with a particle size of 0.3-3.0 microns, D50 not greater than 1.0 micron, and D90 not greater than 1.5 microns by using an air flow pulverizer at a pressure of 6-12 Mpa or a ball mill.

[0038] Preparation of organic carrier: the prepared organic carrier raw materials are weighed, stirred and mixed according to the designed formula proportion, and uniformly dispersed by high-speed centrifugation to obtain the organic carrier for standby use.

[0039] Preparation of main grid silver paste: the selected silver powder and prepared glass powder are added into the prepared organic carrier, then mixed and stirred uniformly, then the thick paste after three-roll milling is filtered, the viscosity of the thick paste is tested, then the silver paste is adjusted to a suitable state for use, and the main grid silver paste is obtained.

[0040] The silver paste for main grid of a silicon solar cell and the electrode cell provided by the application have the following advantages:

[0041] 1. The main grid silver paste for silicon solar cell provided by the application can be widely applied to the main grid lines of different types of silicon solar cells, and can well meet the application requirements of the main grid of the currently mainstream P-type Se-Perc monocrystalline silicon cell and the main grid of the N-type topcon cell, and the main grid of other types of cells with a small market share.

[0042] 2. The main grid silver paste for silicon solar cell provided by the application can be widely matched with different types of sub-grid silver paste, that is, the main grid silver paste for silicon solar cell can be used in combination with different types of sub-grid silver paste for silicon solar cell.

[0043] 3. The main grid silver paste for silicon solar cell provided by the application has the characteristics of high open voltage, high photoelectric conversion efficiency and high main grid peeling strength when combined with different sub-grid silver paste.

[0044] The above advantages are mainly due to the combination of the silver powder and the glass used in the present application. The Pb-Ti-B-Si-O element main body structure glass provided by the present application has the characteristics of good liquefaction effect after melting, and very high glass liquid viscosity in the formula design area. This makes the glass have excellent sintering effect on the silver powder, and improves the density of the silver powder sintered on the main grid. At the same time, the difference between the expansion coefficients of the Pb-Ti-B-Si-O element main body structure glass and the silicon substrate is small, and the glass can be firmly adhered to the silver and silicon wafer after liquid cooling. The glass powder particle size is between 0.3 and 3.0 microns, D50 is not greater than 1.0 microns, and D90 is not greater than 1.5 microns. This further improves the adhesion effect of the main grid silver grid line on the silicon wafer, which realizes high main grid peeling strength. The fine glass powder can be evenly distributed inside the grid line, which ensures the overall distribution of the main grid line and realizes stable main grid peeling strength. In order to match the glass powder of the present application, the present application selects a combination of spherical silver powder with particle size distribution of 0.5-1.5 microns and spherical silver powder with particle size distribution of 2.0-4.0 microns. A small amount of large particle silver powder is used as the support skeleton of the grid line, and a large amount of fine silver powder is used. This increases the contact area of the main grid sintered surface, and ensures the height of the main grid. This is very beneficial to the connection of the main grid and the solder strip, and is a prerequisite for high main grid peeling strength. Furthermore, a large amount of fine silver powder is used, and the glass powder is also fine. The small particles of the glass reduce the problem of local PN damage caused by excessive local glass. The large specific surface area of the fine particle silver powder can effectively reduce the speed of the main grid glass descending to the interface, which reduces the damage of the glass powder to the PN junction in the main grid area, improves the output open voltage of the battery, and promotes the improvement of the battery efficiency. The present application selectively uses Pb-Te-Bi-Zn-Si-O element as the main body structure of the auxiliary glass according to the situation. The auxiliary glass has the characteristics of good affinity with the main grid silver paste and the auxiliary grid silver paste, which can reduce the sintering difference caused by the difference between the main grid and the auxiliary grid, improve the connection effect of the main grid and the different auxiliary grid, and further improve the photoelectric conversion efficiency of the battery. DETAILED DESCRIPTION

[0045] The technical problems, technical solutions and beneficial effects to be solved by the present application are more clearly and explicitly described below. The present application is further described in detail in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0046] The application provides a kind of main grid silver paste for silicon solar cell, not only can be well matched with different types of cell piece main grid, also can widely match the characteristics of different types of subgrid silver paste, with high open voltage, high photoelectric conversion efficiency, high main grid stripping strength characteristics.The application is realized in this way, a kind of main grid conductive silver paste for silicon solar cell, it contains silver powder, glass powder and organic carrier, with the total weight of the main grid silver paste for silicon solar cell as 100%, the weight percentage of each component is as follows:

[0047] Silver powder 80.0%~90.0%;

[0048] Glass powder 0.3%~2.0%;

[0049] Organic carrier 10.0%~20.0%.

[0050] Silver powder is two different particle size silver powder mixed, the first kind of silver powder is spherical silver powder with particle size distribution of 0.5-1.5 μm, the second kind of silver powder is spherical silver powder with particle size distribution of 2.0-4.0 μm, with the total weight of the silver powder of the main grid silver paste for silicon solar cell as 100%, the weight percentage of two different particle size silver powder is as follows:

[0051] The first kind of silver powder 90.0%~95.0%;

[0052] The second kind of silver powder 5.0%~10.0%;

[0053] The glass powder for main grid silver paste of silicon solar cell includes a main glass powder and an auxiliary glass powder, the auxiliary glass powder can be selected to add or not, the particle size distribution of the main glass powder and the auxiliary glass powder is between 0.3~3.0 μm, D50 is not more than 1.0 μm, D90 is not more than 1.5 μm, with the total weight of the glass powder for main grid silver paste of silicon solar cell as 100%, the weight composition ratio of the main glass powder and the auxiliary glass powder is as follows:

[0054] Main glass powder 60.0%~100.0%;

[0055] Auxiliary glass powder 0.0%~40.0%.

[0056] The main glass powder is a Pb-Ti-B-Si-O element main structure glass with added part of other element substances, with the molar percentage content of the main glass powder components as 100%, the molar composition ratio of each substance contained in the main glass powder is as follows:

[0057] PbO 25.0%~45.0%;

[0058] TiO2 5.0%~20.0%;

[0059] B2O3 5.0%~15.0%;

[0060] SiO2 20.0%~45.0%;

[0061] Other element substance 0.0%~20.0%.

[0062] The Pb-Ti-B-Si-O main glass powder for the main grid silver paste of silicon solar cells also includes some modified additive substances, which are one or more of substances containing Te, Al, Cu, Zn, Ca, Mg, Tl, W, Ge, Bi, Mn, Cr, Sb elements.

[0063] The auxiliary glass powder is a Pb-Te-Bi-Zn-Si-O element main structure glass containing part of other element substances, and the molar composition ratio of each substance contained in the auxiliary glass powder is, for example, as follows, based on the molar percentage content of the auxiliary glass powder component being 100%:

[0064] PbO 30.0%~45.0%;

[0065] TeO2 30.0%~45.0%;

[0066] Bi2O3 5.0%~10.0%;

[0067] SiO2 0.0%~10.0%;

[0068] ZnO 2.5%~10.0%;

[0069] Other element substance 0.0%~15.0%.

[0070] The Pb-Te-Bi-Zn-Si-O element main structure auxiliary glass powder for the main grid silver paste of silicon solar cells also includes some modified additive substances, which are one or more of substances containing Al, B, Cu, Mg, Tl, W, Ge elements.

[0071] The preparation raw material of the main glass powder or the auxiliary glass powder is an oxide of the raw material or a substance that can be decomposed to obtain these oxides or a substance that can be decomposed to obtain a complex of the oxide formation of the elements in the glass composition.

[0072] The organic carrier for the main grid silver paste of silicon solar cells includes an organic solvent, an organic resin, and a defoaming agent, and the content of each component is as follows, based on the total weight of the organic carrier being 100%:

[0073] Organic solvent 70.0%~90.0%;

[0074] Organic resin 5.0%~20.0%;

[0075] Defoamer 5.0%~20.0%.

[0076] This invention also provides a method for preparing silver paste for a silicon solar cell, characterized by comprising the following steps:

[0077] Preparation of glass powder: Weigh the raw materials according to the designed glass powder composition, mix the raw materials evenly, add them to a crucible, place the crucible in a muffle furnace, and keep it at 1000℃-1300℃ for 20-60 minutes until the raw materials are completely melted and homogenized. Remove the raw materials and pour them into cooling water for cooling. Then filter out the glass particles and dry them at 100℃-130℃. After drying, cool them to room temperature, and then add the dried glass particles to a disc mill and grind them into primary glass powder with a disc gap of 50-200 micrometers. Finally, pulverize the primary glass powder with an air jet mill under a pressure of 6-12 MPa or grind it with a ball mill to obtain glass powder with a particle size between 0.3 and 3.0 μm, D50 not greater than 1.0 μm, and D90 not greater than 1.5 μm for later use.

[0078] Preparation of organic carrier: The prepared organic carrier raw materials are weighed, stirred and mixed according to the designed formula ratio, and dispersed evenly by high-speed centrifugation to obtain the organic carrier for later use;

[0079] Preparation of main grid silver paste: Selected silver powder and prepared glass powder are added to the prepared organic carrier, and then mixed and stirred evenly. After slurrying with a three-roll mill and filtering, the viscosity of the coarse slurry is tested. After slurry adjustment, the viscosity of the silver paste is adjusted to a better state for use before being bottled to obtain the main grid silver paste.

[0080] The following description is based on specific embodiments:

[0081] Preparation of the main glass powder: Weigh the raw materials according to the designed glass powder composition, mix them evenly, add them to a crucible, place the crucible in a muffle furnace, and keep it at 1000℃-1300℃ for 20-60 minutes until the raw materials are completely melted and homogenized. Remove the crucible and pour it into cooling water for cooling. Then filter out the glass particles and dry them at 100℃-130℃. After drying, cool them to room temperature, and then add the dried glass particles to a disc mill to grind them into primary glass powder with a disc gap of 50-200 micrometers. Finally, pulverize the primary glass powder with an air jet mill under a pressure of 6-12 MPa or grind it with a ball mill to obtain glass powder with a particle size between 0.3 and 3.0 μm, D50 not greater than 1.0 μm, and D90 not greater than 1.5 μm for later use. The powder is numbered A01-A06. The specific molar composition ratio of each glass is shown in Table 1.

[0082] Table 1. Molar percentage of main glass composition (at%)

[0083] Name A01 A02 A03 A04 A05 A06 PbO 31.5 25.0 45.0 37.5 38.2 33.0 TiO2 10.5 5.2 9.6 15.0 13.2 12.0 B2O2 9.0 15.0 5.0 7.5 10.5 8.4 SiO2 42.0 44.8 20.6 26.5 27.0 39.2 TeO2 0.7 　 　 1.0 　 　 Al2O3 　 　 1.0 0.4 　 　 CuO 　 2.0 　 9.6 10.5 　 ZnO 　 5.0 　 　 　 　 CaCO3 　 　 3.5 　 　 1.6 MgO 　 　 0.5 　 　 　 [Ti2O3] 　 　 2.0 0.9 　 　 WO3 　 　 1.0 　 　 　 GeO2 4.8 　 6.8 　 　 5.8 Bi2O3 1.5 　 　 　 　 　 MnO2 　 　 3.0 1.0 0.6 　 Cr2O3 　 　 　 0.6 　 　 Sb2O3 　 3.0 2.0

[0084] Preparation of auxiliary glass powder: the auxiliary glass powder is prepared by weighing the raw materials according to the designed glass powder composition, then mixing the raw materials uniformly, adding them into a crucible, placing the crucible in a muffle furnace, and keeping it at 1000-1300°C for 20-60 min. After the raw materials are completely melted and homogenized, they are taken out, poured into cooling water for cooling, and then the glass particles are filtered out and dried at 100-130°C. After drying, the glass particles are cooled to room temperature, and then added into a disc mill to be crushed into primary glass powder with a gap of 50-200 microns. Finally, the primary glass powder is crushed by an air jet mill under a pressure of 6-12 MPa or a ball mill to obtain glass powder with a particle size of 0.3-3.0 microns, D50 not greater than 1.0 micron, and D90 not greater than 1.5 micron. The glass powder is numbered B01-B04, and the specific molar composition ratio of each glass is shown in Table 1.

[0085] Table 2 Auxiliary glass composition molar percentage table (at%)

[0086] Name B01 B02 B03 B04 PbO 37.5 30.1 45.0 36.0 TeO2 35.9 44.8 30.0 36.0 Bi2O3 7.2 5.0 7.7 9.8 SiO2 7.3 9.7 　 6.5 ZnO 5.4 8.0 2.5 6.0 Al2O3 　 0.5 0.6 　 B2O3 0.8 　 　 1.2 CuO 2.4 　 0.6 1.5 MgO 　 1.3 　 　 [Ti2O3] 　 0.6 1.2 　 WO3 3.5 　 2.2 3.0 GeO2 　 　 10.2

[0087] Preparation of organic carrier: the prepared organic carrier raw materials are weighed, stirred and mixed according to the designed formula ratio, and uniformly dispersed by high-speed centrifugation to obtain the organic carrier C01-C04 for standby. The weight composition ratio of each organic carrier is shown in Table 3.

[0088] Table 3 Organic carrier composition weight percentage table (wt%)

[0089] Name C01 C02 C03 C04 Organic solvent 80.5 70.3 75.5 89.8 Organic resin 10.5 9.9 19.5 5.0 Defoamer 9.0 19.8 5.0 5.2

[0090] Preparation of main grid silver paste: from the prepared first and second silver powders that meet the conditions, the prepared main glass A01-A06, the prepared auxiliary glass powder B01-B04, and the prepared organic carrier C01-C04, appropriate types of materials are selected, and the silver powder, the prepared main glass, the prepared auxiliary glass powder, and the prepared organic carrier are added according to the mass ratio, then mixed and stirred uniformly, and then the coarse slurry is tested for viscosity after being rolled by a three-roll mill. After adjusting the slurry, the silver paste is adjusted to a better state for use, and then canned to obtain the main grid silver paste D01-D12. The specific mass composition and collocation mode are shown in Table 4.

[0091] Table 4 Main grid silver paste composition and weight percentage content table (wt%)

[0092] No. First silver powder content Second silver powder content Main glass / content Auxiliary glass / content Organic carrier / content D01 78.5 8.7 A04 / 0.7 B01 / 0.1 C01 / 12.0 D02 82.4 4.3 A01 / 1.3 　 C03 / 12.0 D03 80.5 8.9 A04 / 0.6 　 C01 / 10.0 D04 76.4 6.6 A06 / 1.6 B02 / 0.4 C02 / 15.0 D05 76.6 7.6 A01 / 0.7 B04 / 0.1 C04 / 15.0 D06 80.0 5.2 A05 / 1.0 　 C01 / 13.8 D07 75.0 6.5 A02 / 0.5 　 C02 / 18.0 D08 76.2 8.0 A03 / 1.1 B03 / 0.7 C04 / 14.0 D09 73.5 6.7 A05 / 0.3 　 C01 / 19.5 D10 80.0 5.2 A04 / 0.6 B01 / 0.2 C04 / 14.0 D11 79.0 6.0 A03 / 0.3 B04 / 0.1 C01 / 14.6 D12 78.0 7.8 A01 / 1.1 　 C02 / 13.1

[0093] The main grid silver paste prepared in the embodiment is printed on the surface of the corresponding cell in a step-by-step printing manner in combination with different sub-grid pastes on different silicon solar cell pieces, and then is subjected to drying, sintering and cooling to obtain a cell containing a printed silver grid line electrode. The obtained cell is subjected to electrical performance testing and main grid peeling strength. In order to observe the use effect of the embodiment of the application, different 3 sub-grid silver pastes of our company are specially selected as the matching silver paste of the sub-grid, wherein X01 is a general type silver paste for P-type single crystal cells, X02 is a Se-perc single crystal special type silver paste, and X03 is an N-type Topcon cell special type silver paste. In order to conveniently observe the electrical performance characteristics of the main grid paste of the application, the main grid paste PVD2B produced by the American DuPont Company is also specially selected to be printed, sintered and subjected to electrical performance testing under the same conditions as the main grid silver paste of the application, and the electrical performance testing results are shown in Table 5.

[0094] Table 5

[0095] Paste code Substrate paste Cell type Open circuit voltage Photoelectric conversion efficiency Peeling strength Aging peeling strength PVD2B X02 Se-perc cell 0.6851V 23.13% 4.07N 1.89N D01 X02 Se-perc cell 0.6865V 23.19% 5.22N 3.07N D02 X02 Se-perc cell 0.6867V 23.18% 5.03N 2.93N D03 X02 Se-perc cell 0.6872V 23.27% 5.19N 3.12N D04 X02 Se-perc cell 0.6866V 23.18% 5.11N 3.10N D05 X02 Se-perc cell 0.6868V 23.20% 5.35N 3.31N D06 X02 Se-perc cell 0.6872V 23.23% 5.28N 3.14N D07 X02 Se-perc cell 0.6868V 23.19% 5.01N 2.96N D08 X02 Se-perc cell 0.6863V 23.17% 5.52N 3.67N D09 X02 Se-perc cell 0.6867V 23.19% 5.06N 2.87N D10 X02 Se-perc cell 0.6871V 23.23% 5.25N 3.24N D11 X02 Se-perc cell 0.6869V 23.21% 5.06N 3.05N D12 X02 Se-perc cell 0.6873V 23.28% 5.19N 3.03N PVD2B X01 Se-perc cell 0.6841V 23.09% 4.11N 1.92N D01 X01 Se-perc cell 0.6857V 23.13% 5.24N 3.13N D02 X01 Se-perc cell 0.6856V 23.11% 5.23N 3.06N D03 X01 Se-perc cell 0.6864V 23.14% 5.28N 3.15N D04 X01 Se-perc cell 0.6859V 23.13% 5.17N 3.09N D05 X01 Se-perc cell 0.6856V 23.10% 5.42N 3.34N D06 X01 Se-perc cell 0.6866V 23.15% 5.31N 3.17N PVD2B X01 Conventional P-type single cell 0.6648V 20.77% 4.12N 1.93N D01 X01 Conventional P-type single cell 0.6661V 20.91% 5.27N 3.01N D02 X01 Conventional P-type single cell 0.6658V 20.88% 5.23N 3.11N D03 X01 Conventional P-type single cell 0.6673V 20.95% 5.38N 3.45N D04 X01 Conventional P-type single cell 0.6665V 20.93% 5.34N 3.26N D05 X01 Conventional P-type single cell 0.6668V 20.93% 5.24N 3.17N D06 X01 Conventional P-type single cell 0.6659V 20.89% 5.16N 3.05N PVD2B X03 Topcon cell 0.6904V 23.21% 4.53N 2.01N D01 X03 Topcon cell 0.6963V 23.47% 5.56N 3.67N D02 X03 Topcon cell 0.6972V 23.54% 5.59N 3.65N D03 X03 Topcon cell 0.6966V 23.50% 5.47N 3.52N D04 X03 Topcon cell 0.6970V 23.51% 5.69N 3.69N D05 X03 Topcon cell 0.6968V 23.51% 5.45N 3.51N D06 X03 Topcon cell 0.6969V 23.52% 5.49N 3.57N

[0096] As can be seen from Table 5, when the DuPont main grid paste PVD2B is combined with different sub-grid silver pastes X02 and X01 on the same cell piece Se-perc cell, the difference in photoelectric conversion efficiency between the combination X01 and the main grid paste of the application is obviously smaller, and the difference in photoelectric conversion efficiency between the combination X02 and the main grid paste of the application is obviously increased, but the open voltage is lower than that of the embodiment of the application; in the case that the sub-grid silver paste is X01, the DuPont main grid paste PVD2B has a smaller difference in photoelectric conversion efficiency on the Se-perc cell than the main grid paste of the embodiment of the application, and has an increased difference in photoelectric conversion efficiency on the conventional P-type single crystal cell than the main grid paste of the application, and the open voltage is also lower than that of the embodiment of the application; in combination with the overall situation in Table 5, under the same conditions, the main grid paste of the embodiment of the application has a higher photoelectric conversion efficiency, a higher open voltage, a higher main grid line peeling strength and a higher main grid line peeling strength after cell aging than the DuPont main grid paste PVD2B. It can be known that the main grid silver paste for a silicon solar cell provided by the application not only can well match the main grid of different types of cell pieces, but also can widely match the characteristics of different types of sub-grid silver paste, has a high open voltage, a high photoelectric conversion efficiency and a high main grid peeling strength.

Claims

1. A main grid silver paste for a silicon solar cell, characterized by, The main grid silver paste for the silicon solar cell contains silver powder, glass powder and organic carrier, and the weight percentage of each component is as follows, based on the total weight of the main grid silver paste for the silicon solar cell being 100%: Silver powder 80.0%-90.0%; Glass powder 0.3%-2.0%; Organic carrier 10.0%-20.0%; The silver powder is a mixture of two different particle sizes, the first being spherical silver powder with a particle size distribution of 0.5-1.5 μm, and the second being spherical silver powder with a particle size distribution of 2.0-4.0 μm, and the weight percentage of the two different particle sizes is as follows, based on the total weight of the silver powder of the main grid silver paste for the silicon solar cell being 100%: First silver powder 90.0%-95.0%; Second silver powder 5.0%-10.0%; The glass powder of the main grid silver paste for the silicon solar cell contains a main glass powder and an auxiliary glass powder, and the auxiliary glass powder can be selected to be added or not, the particle size distribution of the main glass powder and the auxiliary glass powder is between 0.3-3.0 μm, D50 is not greater than 1.0 μm, and D90 is not greater than 1.5 μm, and the weight composition ratio of the main glass powder and the auxiliary glass powder is as follows, based on the total weight of the glass powder of the main grid silver paste for the silicon solar cell being 100%: Main glass powder 60.0%-100.0%; Auxiliary glass powder 0.0%-40.0%; The glass powder of the main grid silver paste for the silicon solar cell is a main glass powder that can be matched with an auxiliary glass powder, and the main glass powder is a Pb-Ti-B-Si-O element main structure glass with additional partial other element substances, and the molar composition ratio of each substance contained in the main glass powder is as follows, based on the molar percentage content of the main glass powder components being 100%: PbO 25.0%-45.0%; TiO2 5.0%-20.0%; B2O3 5.0%-15.0%; SiO2 20.0%-45.0%; Other element substances 0.0%-20.0%; The auxiliary glass powder that can be used with the main glass powder is a Pb-Te-Bi-Zn-Si-O element main structure glass with partial other element substances, and the molar composition ratio of each substance contained in the auxiliary glass powder is as follows, based on the molar percentage content of the auxiliary glass powder components being 100%: PbO 0.0%-45.0%; TeO2 30.0%-45.0%; Bi2O3 5.0%-10.0%; SiO2 0.0%-10.0%; ZnO 2.5%-10.0%; Other element substances 0.0%-15.0%; The Pb-Ti-B-Si-O main glass powder of the main grid silver paste for the silicon solar cell also includes some modified additive substances, and the modified additive substances are one or more of substances containing Te, Al, Cu, Zn, Ca, Mg, Tl, W, Ge, Bi, Mn, Cr, and Sb elements; ​ The Pb-Te-Bi-Zn-Si-O auxiliary glass powder for the main grid silver paste of the silicon solar cell further comprises some modified additive substances, which are one or more of substances containing Al, B, Cu, Mg, Tl, W, and Ge elements.

2. The main grid silver paste for silicon solar cells according to claim 1, wherein the silver paste contains 0.1 to 0.5 parts by weight of the glass frit. The raw materials for preparing the glass powder of the main grid silver paste for the silicon solar cell are the oxides of the elements or substances that can be decomposed into the oxides or compounds that can be decomposed into the oxide-forming substances of the elements in the glass composition.

3. The main grid silver paste for silicon solar cells according to claim 1, wherein the silver paste contains 0.1 to 0.5 parts by weight of the glass frit. The organic carrier of the main grid silver paste for the silicon solar cell comprises an organic solvent, an organic resin, and an antifoaming agent, and the content of each component is as follows, based on 100% of the total weight of the organic carrier: The organic solvent is 70.0%-90.0%; The organic resin is 5.0%-20.0%; The antifoaming agent is 5.0%-20.0%.

4. A method for preparing a main grid silver paste for a silicon solar cell, which prepares the main grid silver paste for a silicon solar cell according to any one of claims 1 to 3, characterized by, The process comprises the following steps: (1) Preparation of the glass powder: the raw materials are weighed and mixed according to the designed composition of the glass powder, then the mixed raw materials are put into a crucible, the crucible is placed in a muffle furnace, and the raw materials are completely melted and homogenized at 1000-1300℃ for 20-60 min. Then, the glass particles are filtered out, dried at 100-130℃, cooled to room temperature, and then ground into primary glass powder in a disc mill at a gap of 50-200 microns. Finally, the primary glass powder is ground into a glass powder with a particle size of 0.3-3.0 microns, a D50 of not more than 1.0 micron, and a D90 of not more than 1.5 microns using an air jet mill at a pressure of 6-12 MPa or a ball mill; (2) Preparation of the organic carrier: the prepared organic carrier raw materials are weighed, stirred, mixed, and uniformly dispersed by high-speed centrifugation to obtain the organic carrier; (3) Preparation of the main grid silver paste: the selected silver powder and the prepared glass powder are added to the prepared organic carrier, which is then uniformly mixed and stirred, and then the paste is prepared by using a three-roll mill, filtered, and tested for viscosity. After adjusting the viscosity of the silver paste to a suitable state, the silver paste is filled into a tank to obtain the main grid silver paste; The silver powder is a mixture of two different particle sizes, the first being a spherical silver powder with a particle size distribution of 0.5-1.5 microns, and the second being a spherical silver powder with a particle size distribution of 2.0-4.0 microns. The weight percentage of the two different particle sizes is as follows, based on 100% of the total weight of the silver powder for the main grid silver paste of the silicon solar cell: The first silver powder is 90.0%-95.0%; The second silver powder is 5.0%-10.0%. The main grid silver paste glass powder for the silicon solar cell comprises a main glass powder and an auxiliary glass powder, the auxiliary glass powder can be selected to be added or not, the particle size distribution of the main glass powder and the auxiliary glass powder is between 0.3-3.0 μm, D50 is not greater than 1.0 μm, D90 is not greater than 1.5 μm, and the weight composition ratio of the main glass powder and the auxiliary glass powder is as follows, taking the total weight of the main grid silver paste glass powder for the silicon solar cell as 100%: The main glass powder is 60.0%-100.0%; The auxiliary glass powder is 0.0%-40.0%.