N-type IBC battery negative electrode grid line silver paste, N-type IBC battery and preparation method thereof

Abstract

The embodiment of the present application provides a kind of N-type IBC battery negative electrode grid silver paste, N-type IIBC battery and preparation method thereof, wherein, the N-type IBC battery negative electrode grid silver paste provided in the embodiment of the present application includes organic auxiliary agent, silver powder, organic binder and doped glass powder, and the doping element of the doped glass powder is antimony, tellurium and tungsten.By doping antimony, tellurium and tungsten elements in glass powder, antimony element is the same as phosphorus, and the doping of N area can be increased;And tellurium and tungsten have the effect of dissolving silver, which can reduce the contact resistivity of silver grid line, improve the fill factor, thereby improving the photoelectric conversion efficiency of battery;Thus, the problem that the existing N-type IBC battery cannot form n+ region, so that the photoelectric conversion efficiency of N-type IBC battery is not good.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of crystalline silicon solar cell manufacturing, in particular to a N-type IBC cell negative electrode grid line silver paste, a N-type IBC cell and a preparation method thereof. BACKGROUND

[0002] The interdigitated back contact (IBC) cell is a new type of cell in which the P / N junction, the base and the contact electrode of the emitter region are arranged in an interdigitated shape on the back surface of the cell. The core technology is to prepare p and n regions in an interdigitated shape and spaced apart on the back surface of the cell.

[0003] At present, the N-type IBC cell uses an N-type original silicon wafer. The p region is doped by using a boron diffusion method combined with a laser SE technology, so as to form a p+ doped region, thereby reducing metal recombination and improving the open voltage. However, the N region cannot be doped by using a tube diffusion method, that is, an N+ region cannot be formed, so that the efficiency of the N-type IBC cell is not improved well. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a N-type IBC cell negative electrode grid line silver paste, a N-type IBC cell and a preparation method thereof, so as to solve the problem that the existing N-type IBC cell cannot form an n+ region, thereby reducing the photoelectric conversion efficiency of the N-type IBC cell.

[0005] In order to solve the above problems, the present application is realized by the following technical scheme:

[0006] The present application provides a N-type IBC cell negative electrode grid line silver paste, wherein the components of the silver paste include an organic additive, silver powder, an organic binder and doped glass powder, and the doping elements of the doped glass powder are antimony, tellurium and tungsten.

[0007] Further, in the silver paste, the mass fractions of the organic additive, the silver powder, the organic binder and the doped glass powder are 0.8-1.5%, 76-84%, 11.3-21.2% and 2-3.2%, respectively.

[0008] Further, in the silver paste, the doped glass powder includes Bi2O3 with a mass percentage of 10-25%, Al2O3 with a mass percentage of 6-8%, SiO2 with a mass percentage of 8-15%, ZnO with a mass percentage of 5-15%, Sb2O3 with a mass percentage of 25-40%, TiO2 with a mass percentage of 5-12%, WO2 with a mass percentage of 5-12%, MgO with a mass percentage of 5-10% and TeO3 with a mass percentage of 15-20%.

[0009] Further, in the silver paste, the D50 of the doped glass powder is 1.5-2 μm.

[0010] Further, the organic adjuvant in the silver paste comprises three or more than three of fatty alcohol ether phosphate, aluminate coupling agent, silane coupling agent, zirconium aluminate coupling agent, lauryl phosphate, silicone oil, dibasic acid ester, lauryl alcohol phosphate mixture.

[0011] Further, the organic binder in the silver paste comprises high molecular polymer resin and organic solvent.

[0012] The mass fraction of the high molecular polymer in the organic binder is 10-15%.

[0013] The mass fraction of the organic solvent in the organic binder is 85-90%.

[0014] Further, the high molecular polymer in the silver paste is resin-50.

[0015] The organic solvent comprises at least five of benzyl alcohol, diethyl phthalate, terpineol, butyl carbityl alcohol, butyl carbityl alcohol acetate, tributyl citrate, Span 85 and alcohol ester twelve.

[0016] Further, the silver powder in the silver paste comprises micron spherical silver powder and nanometer spherical silver powder.

[0017] The application further provides a preparation method of the N-type IBC cell.

[0018] After forming the interdigital spaced n-type doped region and p-type doped region on the back of the N-type silicon wafer, a passivation layer is formed on the surface of the n-type doped region and p-type doped region.

[0019] An opening is formed in the first region of the passivation layer and in communication with the p-type doped region, and an aluminum paste is printed on the opening, and a silver paste is printed on the second region of the passivation layer; the projection of the first region is within the range of the p-type doped region, and the projection of the second region is within the range of the n-type doped region; wherein the components of the silver paste comprise organic adjuvant, silver powder, organic binder and doped glass powder, and the doping elements of the doped glass powder are antimony, tellurium and tungsten.

[0020] The N-type silicon wafer with the aluminum paste printed on the opening and the silver paste printed on the second region is subjected to high-temperature sintering to obtain the N-type IBC cell.

[0021] The application further provides an N-type IBC cell prepared by the above method.

[0022] Compared with the prior art, the application has the following advantages:

[0023] In the embodiment of the present application, the N-type IBC battery negative grid line silver paste provided comprises organic additives, silver powder, organic binder and doped glass powder, and the doping elements of the doped glass powder are antimony, tellurium and tungsten. Among them, the antimony element is a pentavalent element like phosphorus, which can increase the doping of the N region; and tellurium and tungsten have a silver dissolving effect, which can reduce the contact resistivity of the silver grid line and improve the fill factor, thereby improving the photoelectric conversion efficiency of the battery; thus solving the problem that the existing N-type IBC battery cannot form an n+ region, resulting in poor photoelectric conversion efficiency of the N-type IBC battery.

[0024] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a preparation method flow chart of the N-type IBC battery negative grid line silver paste provided by the embodiment of the present application;

[0026] Figure 2 is a preparation method flow chart of the N-type IBC battery provided by the embodiment of the present application. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned objects, features and advantages of the present application more apparent and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0028] The applicant of the present application found that the current N-type IBC battery uses an N-type original silicon wafer, and the P-type region uses a boron expansion plus laser SE technology to reduce metal recombination and improve the open voltage; but the N region cannot be doped by a tubular diffusion method, that is, an n+ region cannot be formed, so that the efficiency of the N-type IBC battery cannot be effectively improved.

[0029] In order to solve the above-mentioned problems, the embodiment of the present application provides an N-type IBC battery negative grid line silver paste, and the components of the silver paste include organic additives, silver powder, organic binder and doped glass powder, and the doping elements of the doped glass powder are antimony, tellurium and tungsten.

[0030] The N-type IBC battery negative grid line silver paste provided by the embodiment of the present application is used to form the negative grid line of the N-type IBC battery, which can be the negative main grid and / or the negative fine grid; wherein the back surface of the above-mentioned N-type IBC battery is a P-type region formed by boron expansion plus laser SE technology.

[0031] The silver powder is a main component, and the silver powder mainly forms an N-type emitter of the battery; the doped glass powder is an inorganic adhesive, which is melted into a liquid state under high temperature conditions, and is condensed when cooled to play a role of adhesion, and the doped element antimony element and phosphorus are both pentavalent elements, which can increase N area doping; and tellurium and tungsten have a silver dissolving effect, which can reduce the contact resistance of the silver grid line, improve the fill factor, and thus improve the efficiency of the battery, thereby solving the problem that the existing N-type IBC battery cannot form an n+ area, and the photoelectric conversion efficiency of the N-type IBC battery is poor; the organic binder can ensure the overall adhesion effect; and the organic additive can reduce the overall viscosity of the silver paste.

[0032] The silver paste provided by the embodiment of the application can effectively form an N-type area on an N-type silicon wafer, has better contact with the battery wafer itself, has smaller string resistance than the traditional silver paste, and can improve the efficiency of the battery by 0.08%.

[0033] In the embodiment of the application, the antimony, tellurium and tungsten are doped into the glass powder in the form of oxides to form the doped glass powder. That is, the doped glass powder includes the oxide of antimony, the oxide of tellurium and the oxide of tungsten. Optionally, the oxide of antimony can be Sb2O3, the oxide of tellurium can be TeO3, and the oxide of tungsten can be WO2.

[0034] Optionally, in an embodiment, the doped glass powder includes Bi2O3 with a mass percentage of 10-25%, Al2O3 with a mass percentage of 6-8%, SiO2 with a mass percentage of 8-15%, ZnO with a mass percentage of 5-15%, Sb2O3 with a mass percentage of 25-40%, TiO2 with a mass percentage of 5-12%, WO2 with a mass percentage of 5-12%, MgO with a mass percentage of 5-10%, and TeO3 with a mass percentage of 15-20%. The D50 of the doped glass powder is 1.5-2 μm. If the D50 is less than 1.5 μm, the activity of the doped glass is too large, and if the D50 is greater than 2 μm, the activity of the doped glass is too small. Optionally, the D50 of the glass powder is 1.6-1.8 μm.

[0035] The Bi2O3 is a main network structure; the Al2O3 can adjust the stability of the glass and improve the viscosity; the SiO2 is a glass network former, which promotes the stability of the glass and reduces the melting point of the glass; the ZnO can break the network structure and promote the glass crystallization; the Sb2O3 is used for N-type doping to achieve a similar N area doping effect as phosphorus; the TiO2 is used for local crystallization; the MgO is used for reducing the melting point; the WO2 is used for dissolving silver for larger silver powder, and the TeO3 is used for dissolving silver for smaller silver powder, and can perform local microcrystallization and reduce the melting point.

[0036] Optionally, in an embodiment, the mass percentages of the organic additive, the silver powder, the organic binder and the doped glass powder in the silver paste are 0.8-1.5%, 76-84%, 11.3-21.2% and 2-3.2%, respectively.

[0037] Optionally, in one embodiment, the mass fractions of the organic auxiliary agent, silver powder, organic binder and doped glass powder in the silver paste are 1-1.2%, 78-82%, 15-18% and 2.5-3%, respectively.

[0038] For example, the mass fractions of the organic auxiliary agent, silver powder, organic binder and doped glass powder in the silver paste are 0.8%, 84%, 12% and 3.2%, respectively.

[0039] For example, the mass fractions of the organic auxiliary agent, silver powder, organic binder and doped glass powder in the silver paste are 1.5%, 76%, 20.5% and 2%, respectively.

[0040] For example, the mass fractions of the organic auxiliary agent, silver powder, organic binder and doped glass powder in the silver paste are 1.5%, 84%, 11.3% and 3.2%, respectively.

[0041] For example, the mass fractions of the organic auxiliary agent, silver powder, organic binder and doped glass powder in the silver paste are 0.8%, 76%, 21.2% and 2%, respectively.

[0042] For example, the mass fractions of the organic auxiliary agent, silver powder, organic binder and doped glass powder in the silver paste are 1.1%, 79%, 17% and 2.9%, respectively.

[0043] Optionally, in one embodiment, the silver powder includes microspherical silver powder and nanospherical silver powder. The nanoscale spherical silver powder can fill and penetrate into the gaps between the microscale silver powder due to the gaps between the microscale silver powder and the silver powder.

[0044] Optionally, in one embodiment, the silver powder includes microspherical silver powder with a mass fraction of 85-90% and nanospherical silver powder with a mass fraction of 10-15%.

[0045] Optionally, in one embodiment, the silver powder includes microspherical silver powder with a purity of 3 nines, a mass fraction of 85-90% and a D50 of 5-6 μm, and nanospherical silver powder with a purity of 3 nines and a mass fraction of 10-15%.

[0046] Optionally, in one embodiment, the organic auxiliary agent includes one or more of fatty alcohol ether phosphate, aluminate coupling agent, silane coupling agent, zirconium aluminate coupling agent, lauryl phosphate, silicone oil, dibasic acid ester, lauryl alcohol phosphate mixture, DiGol 655, BYK 109.

[0047] In the N-type IBC battery negative electrode grid silver paste provided by the embodiment of the present application, the organic binder includes a high polymer resin and an organic solvent; wherein the high polymer resin is dissolved in the organic solvent, so that the organic solvent can act as an organic adhesive, that is, so that the paste can play a role of bonding the powder after being dried.

[0048] Optionally, in an embodiment, the mass fraction of the high polymer in the organic adhesive is 10-15%; and the mass fraction of the organic solvent in the organic adhesive is 85-90%.

[0049] Optionally, in some embodiments, the mass fraction of the high polymer in the organic adhesive is 12-13%; and the mass fraction of the organic solvent in the organic adhesive is 87-88%.

[0050] Optionally, in an embodiment, the high polymer is one or more of ethyl cellulose-N20, ethyl cellulose N-50, and ethyl cellulose-N100.

[0051] The organic solvent includes at least 5 of benzyl alcohol, diethyl phthalate, terpineol, butyl carbityl alcohol, butyl carbityl alcohol acetate, tributyl citrate, Span 85, and alcohol ester twelve.

[0052] The embodiment of the present application further provides a preparation method of the N-type IBC battery negative electrode grid silver paste. Figure 1 As shown in the figure, the method includes steps 101-102:

[0053] In step 101, silver powder, an organic adhesive, and doped glass powder are mixed to obtain a mixture; wherein the doped element of the doped glass powder is antimony, tellurium, and tungsten.

[0054] In step 102, after the mixture is ground, an organic additive is added to obtain the N-type IBC battery negative electrode grid silver paste.

[0055] In step 101, 76-84% of the total mass of raw materials of silver powder, 11.3-21.2% of the organic binder, and 2-3.2% of the doped glass powder are weighed and mixed, and a disperser is used for dispersion to obtain the mixture.

[0056] Optionally, in an embodiment, in step 101, the organic adhesive and the nanoscale spherical silver powder are first mixed and dispersed by using a disperser, and then the micrometer-scale spherical silver powder and the doped glass powder are added and dispersed by using the disperser again, and then the mixture is ground to obtain the mixture.

[0057] In step 102, the mixture is ground and 0.8-1.5% of an organic additive is added to the total mass of the raw material, and then high-speed dispersion is performed to obtain silver paste which can be used to form a negative grid line in contact with the N-type region on the back of the IBC battery and can significantly improve the photoelectric conversion efficiency of the battery.

[0058] In the embodiment of the present application, by doping antimony, tellurium and tungsten elements in the glass powder, the antimony element is a pentavalent element like phosphorus, which can increase the doping of the N region; and tellurium and tungsten have a silver dissolving effect, which can reduce the contact resistance of the silver grid line and improve the fill factor, thereby improving the photoelectric conversion efficiency of the battery; thus solving the problem that the existing N-type IBC battery cannot form an n+ region, resulting in poor photoelectric conversion efficiency of the N-type IBC battery.

[0059] Optionally, in the preparation method provided in the embodiment of the present application, the doping glass powder comprises Bi2O3 in a mass percentage of 10-25%, Al2O3 in a mass percentage of 6-8%, SiO2 in a mass percentage of 8-15%, ZnO in a mass percentage of 5-15%, Sb2O3 in a mass percentage of 25-40%, TiO2 in a mass percentage of 5-12%, WO2 in a mass percentage of 5-12%, MgO in a mass percentage of 5-10%, and TeO3 in a mass percentage of 15-20%.

[0060] Optionally, in the preparation method provided in the embodiment of the present application, the D50 of the doping glass powder is 1.5-2 μm.

[0061] Optionally, in the preparation method provided in the embodiment of the present application, the organic additive comprises three or more of fatty alcohol ether phosphate, aluminate coupling agent, silane coupling agent, zirconium aluminate coupling agent, lauryl phosphate, silicone oil, dibasic acid ester, lauryl alcohol phosphate, and a mixture thereof.

[0062] Optionally, in the preparation method provided in the embodiment of the present application, the organic binder comprises a high molecular polymer resin and an organic solvent.

[0063] The mass percentage of the high molecular polymer in the organic binder is 10-15%.

[0064] The mass percentage of the organic solvent in the organic binder is 85-90%.

[0065] Optionally, in the preparation method provided in the embodiment of the present application, the high molecular polymer is resin-50.

[0066] The organic solvent comprises at least five of benzyl alcohol, diethyl phthalate, terpineol, butyl carbityl alcohol, butyl carbityl alcohol acetate, tributyl citrate, Span 85, and alcohol ester twelve.

[0067] Optionally, in the preparation method provided in the embodiment of the present application, the silver powder comprises micron-sphere silver powder and nano-sphere silver powder.

[0068] The present application also provides a preparation method of the N-type IBC cell, wherein, as shown in the figure, the method comprises steps 201-203: Figure 2

[0069] Step 201: after forming the interdigitated and spaced n-type doped regions and p-type doped regions on the back surface of the N-type silicon wafer, a passivation layer is formed on the surface of the n-type doped regions and p-type doped regions.

[0070] Step 202: an opening is formed in the first region of the passivation layer and in communication with the p-type doped regions, and an aluminum paste is printed at the opening, and a silver paste is printed in the second region of the passivation layer; the projection of the first region is within the range of the p-type doped regions, and the projection of the second region is within the range of the n-type doped regions; wherein the composition of the silver paste comprises an organic additive, silver powder, an organic binder and doped glass powder, and the doping elements of the doped glass powder are antimony, tellurium and tungsten.

[0071] Step 203: the N-type silicon wafer with the aluminum paste printed in the opening and the silver paste printed in the second region is subjected to high-temperature sintering to obtain the N-type IBC cell.

[0072] In the above step 201, the N-type silicon wafer is first subjected to alkali texturing, and then the interdigitated and spaced n-type doped regions and p-type doped regions are formed on the back surface of the silicon wafer, and then a silicon oxide layer and / or a silicon nitride layer covering the entire back surface of the silicon wafer is deposited as the passivation layer.

[0073] The P-type doped region is formed by the boron extension and laser SE process on the N-type silicon wafer, so as to further reduce metal recombination and improve the open voltage.

[0074] In the above step 202, the silicon wafer after forming the passivation layer is taken, and an opening in communication with the p-type doped regions is formed in the first region of the passivation layer by laser slotting or the like, and the projection of the first region is within the range of the p-type doped regions, and then an aluminum paste is screen printed at the opening to form a positive grid line in conduction with the p-type doped regions, wherein the aluminum paste can be a traditional aluminum paste; at the same time, the silver paste is also printed in the second region of the back passivation layer, and the projection of the second region is within the range of the n-type doped regions, so as to form a negative grid line spaced from the positive grid line.

[0075] ​In step 203, the silver paste is printed on the passivation layer region above the n-type doped region, and then high-temperature sintering is performed, so that the passivation layer is burned through and the negative electrode grid line in contact with the n-type doped region is formed; at the same time, because the glass powder is doped with antimony, tellurium and tungsten elements, the antimony element is a pentavalent element like phosphorus, which can increase the doping of the N region; and tellurium and tungsten have the effect of dissolving silver, which can reduce the contact resistivity of the silver grid line and improve the fill factor, thereby improving the photoelectric conversion efficiency of the battery.

[0076] The application will be described in detail below through examples.

[0077] Example 1

[0078] (1) Provide silver paste: the silver paste is composed of 1.2 parts of organic auxiliary agent, 80 parts of silver powder, 16.8 parts of organic binder and 2 parts of doped glass powder by mass fraction;

[0079] Among them, the organic auxiliary agent includes three kinds of silane coupling agent, silicone oil, lauryl alcohol phosphate mixture; the silver powder includes micron-level spherical silver powder with a purity of 3 nine and a mass fraction of 90%, and nanometer spherical silver powder with a purity of 3 nine and a mass fraction of 10%; the organic binder includes resin-50 with a mass fraction of 10% and organic solvent with a mass fraction of 90%, and the organic solvent includes benzyl alcohol, diethyl phthalate, terpineol, butyl carbol, butyl carbol acetate and tributyl citrate;

[0080] Among them, the doped glass powder is obtained by sintering and crushing Bi2O3 with a mass percentage of 14%, Al2O3 with a mass percentage of 6%, SiO2 with a mass percentage of 6%, ZnO with a mass percentage of 6%, Sb2O3 with a mass percentage of 30%, TiO2 with a mass percentage of 5%, WO2 with a mass percentage of 10%, MgO with a mass percentage of 8% and TeO3 with a mass percentage of 15%.

[0081] (2) After forming a silicon oxide layer and a polysilicon layer on the back of an N-type silicon wafer with a size of 182mmx182mm in turn, boron diffusion and laser SE treatment are performed on the back polysilicon layer;

[0082] (3) Laser grooving is performed on the back of the N-type silicon wafer after phosphorus doping to form n-type doped regions and p-type doped regions arranged in an interdigital manner, and the front polysilicon layer is removed;

[0083] (4) After removing the front polysilicon layer and forming a double-sided aluminum oxide layer, a front silicon nitride layer and a back silicon nitride layer in turn, laser grooving is performed on the back silicon nitride layer opposite to the p-type doped region to form an opening, the above-mentioned aluminum paste is printed on the opening through a 480-mesh silk screen, and the above-mentioned silver paste is printed on the back silicon nitride layer opposite to the n-type doped region;

[0084] (5) High-temperature sintering is performed on the silicon wafer in a sintering furnace, and the peak temperature of sintering is 772℃, so as to obtain an N-type IBC battery.

[0085] Example 2

[0086] Example 2 differs from Example 1 in that in step (1), the doped glass frit comprises 10% Bi2O3, 8% Al2O3, 8% SiO2, 7% ZnO, 25% Sb2O3, 12% TiO2, 5% WO2, 10% MgO, and 15% TeO3 by mass.

[0087] Example 3

[0088] Example 3 differs from Example 1 in that in step (1), the doped glass frit comprises 10% Bi2O3, 8% Al2O3, 8% SiO2, 7% ZnO, 25% Sb2O3, 5% TiO2, 12% WO2, 5% MgO, and 20% TeO3 by mass.

[0089] Example 4

[0090] Example 4 differs from Example 1 in that in step (1), the doped glass frit comprises 10% Bi2O3, 8% Al2O3, 8% SiO2, 7% ZnO, 25% Sb2O3, 7% TiO2, 8% WO2, 7% MgO, and 18% TeO3 by mass.

[0091] Example 5

[0092] Example 5 differs from Example 1 in that in step (1), the silver paste consists of 0.8 parts by mass of the organic aid, 84 parts of the silver powder, 12 parts of the organic binder, and 3.2 parts of the doped glass frit.

[0093] Example 6

[0094] Example 6 differs from Example 1 in that in step (1), the silver paste consists of 1.5 parts by mass of the organic aid, 76 parts of the silver powder, 20.5 parts of the organic binder, and 2 parts of the doped glass frit.

[0095] Comparative Example 1

[0096] Comparative Example 1 differs from Example 1 in that in step (1), the silver paste consists of 1.2 parts by mass of the organic aid, 80 parts of the silver powder, 16.8 parts of the organic binder, and 2 parts of the glass frit, which comprises 24% Bi2O3, 22% Al2O3, 10% SiO2, 16% ZnO, 15% TiO2, 13% MgO by mass.

[0097] The electrical performance of the N-type IBC batteries prepared in the above embodiments and comparative examples was tested, and the results are shown in Table 1 below:

[0098] Table 1

[0099]

[0100] Comparing Examples 1 to 6 with Comparative Example 1, it can be seen that by doping antimony, tellurium and tungsten elements into the glass powder, the contact resistivity of the silver grid line can be reduced, the fill factor can be increased, and the photoelectric conversion efficiency of the battery can be improved, with the battery efficiency increased by 0.08%.

[0101] In summary, in this embodiment, by doping the glass powder with antimony, tellurium, and tungsten, antimony, like phosphorus, is a pentavalent element, which can increase the doping of the N-region; while tellurium and tungsten have a silver-dissolving effect, which can reduce the contact resistivity of the silver grid lines and increase the fill factor, thereby improving the photoelectric conversion efficiency of the battery; thus solving the problem that existing N-type IBC batteries cannot form an n+ region, resulting in poor photoelectric conversion efficiency of N-type IBC batteries.

[0102] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0103] The foregoing has provided a detailed description of the silver paste for the negative electrode grid of an N-type IBC battery, the N-type IBC battery itself, and its preparation method. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A silver paste for the negative electrode grid lines of an N-type IBC battery, characterized in that, The silver paste comprises organic additives, silver powder, organic binder, and doped glass powder, wherein the doping elements of the doped glass powder are antimony, tellurium, and tungsten; and the organic binder comprises polymer resin and organic solvent. The doped glass powder comprises 10-25% Bi2O3, 6-8% Al2O3, 8-15% SiO2, 5-15% ZnO, 25-40% Sb2O3, 5-12% TiO2, 5-12% WO2, 5-10% MgO and 15-20% TeO3 by mass. The mass fractions of the organic additives, silver powder, organic binder, and doped glass powder are 0.8-1.5%, 76-84%, 11.3-21.2%, and 2-3.2%, respectively.

2. The silver paste according to claim 1, characterized in that, The D50 of the doped glass powder is 1.5~2μm.

3. The silver paste according to claim 1, characterized in that, The organic additives include three or more of the following: fatty alcohol ether phosphate, aluminate coupling agent, silane coupling agent, zirconium aluminate coupling agent, silicone oil, diester, and a mixture of lauryl phosphate.

4. The silver paste according to claim 1, characterized in that, The polymer in the organic adhesive has a mass fraction of 10-15%; The organic solvent has a mass fraction of 85-90% in the organic adhesive.

5. The silver paste according to claim 4, characterized in that, The organic solvent includes at least five of the following: benzyl alcohol, diethyl phthalate, terpineol, butyl carbiol, butyl carbiol acetate, tributyl citrate, Span 85, and ester twelve.

6. The silver paste according to claim 1, characterized in that, The silver powder includes micron-sized spherical silver powder and nano-sized spherical silver powder.

7. A method for preparing an N-type IBC battery, characterized in that, include: After forming interdigitated n-type doped regions and p-type doped regions on the back side of an N-type silicon wafer, a passivation layer is formed on the surface of the n-type doped regions and p-type doped regions. An opening communicating with a p-type doped region is formed in a first region of the passivation layer, and aluminum paste is printed at the opening. Silver paste is printed in a second region of the passivation layer. The projection of the first region is within the p-type doped region, and the projection of the second region is within the n-type doped region. The silver paste comprises an organic additive, silver powder, an organic binder, and doped glass powder, wherein the doping elements of the doped glass powder are antimony, tellurium, and tungsten. The organic binder comprises a polymer resin and an organic solvent. The mass fractions of the organic additive, silver powder, organic binder, and doped glass powder are 0.8-1.5%, 76-84%, 11.3-21.2%, and 2-3.2%, respectively. The doped glass powder comprises 10-25% Bi2O3, 6-8% Al2O3, 8-15% SiO2, 5-15% ZnO, 25-40% Sb2O3, 5-12% TiO2, 5-12% WO2, 5-10% MgO and 15-20% TeO3 by mass. An N-type silicon wafer with aluminum paste printed in the opening and silver paste printed in the second region is subjected to high-temperature sintering to obtain an N-type IBC cell.

8. An N-type IBC battery, characterized in that, It is prepared by the method described in claim 7.

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