A boron aluminum paste, an n-type ibc cell and a preparation method thereof

Abstract

The embodiment of the present application provides a boron-aluminum paste, an N-type IBC cell and a preparation method thereof, wherein the boron-aluminum paste is used for forming a p-type doped region in the N-type IBC cell by laser doping, and the components of the boron-aluminum paste include aluminum powder, silver powder, boron powder, glass powder, an organic binder and an organic additive. By adding the boron powder in the aluminum paste, performing high-temperature sintering and laser doping after being directly printed on an n-type original silicon region, high-concentration boron doping can be achieved on the n-type original silicon region to form a p-type doped region, the side effects caused by the traditional tube-type boron source doping method are avoided, the conversion efficiency of the cell is ensured, and thus the problems that the forming method of the p-type doped region of the existing N-type IBC cell is complex and has many side effects and is easy to affect the photoelectric conversion efficiency of the cell are solved.

Description

Technical Field

[0001] This invention relates to the field of crystalline silicon solar cell manufacturing technology, and in particular to a boron-aluminum paste, an N-type IBC cell, and a method for preparing the same. Background Technology

[0002] Interdigitated Back Contact (IBC) batteries are a new type of battery in which the P / N junction, substrate and emitter contact electrodes are made in an interdigitated shape on the back of the battery. The core technology is to prepare high-quality p-regions and n-regions that are interdigitated and spaced apart in an interdigitated shape on the back of the battery.

[0003] The p-type doped region of existing N-type IBC cells is obtained through boron diffusion treatment, which is complex and has many side effects, and can easily affect the photoelectric conversion efficiency of the cell. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a boron-aluminum paste, an N-type IBC cell and its preparation method, so as to solve the problem that the existing N-type IBC cell has a complex process for forming the p-type doped region and has many side effects, which can easily affect the photoelectric conversion efficiency of the cell.

[0005] To solve the above problems, the present invention is achieved through the following technical solution:

[0006] This invention proposes a boron-aluminum paste, which is used for laser doping to form a p-type doped region in an N-type IBC cell. The components of the boron-aluminum paste include aluminum powder, silver powder, boron powder, glass powder, organic binder, and organic additives.

[0007] Further, in the boron-aluminum paste, the organic additives account for 0.3-0.8% by mass; the boron powder accounts for 0.5-1% by mass; the aluminum powder accounts for 74-80% by mass; the organic binder accounts for 16.7-24.2% by mass; and the glass powder accounts for 1-1.5% by mass.

[0008] Furthermore, in the boron-aluminum paste, the boron powder comprises elemental boron and / or a boron-aluminum alloy.

[0009] Furthermore, in the boron-aluminum paste, the organic additives include two or more of the following: fatty alcohol ether phosphate, aluminate coupling agent, silane coupling agent, zirconium aluminate coupling agent, lauryl phosphate, silicone oil, diester, and lauryl phosphate.

[0010] Furthermore, in the boron-aluminum paste, the aluminum powder comprises 85-90% by mass micron-sized spherical aluminum powder and 10-15% by mass nano-sized spherical aluminum powder.

[0011] Furthermore, in the boron-aluminum paste, the organic binder includes a polymer resin and an organic solvent;

[0012] The polymer in the organic binder has a mass fraction of 6-10%;

[0013] The organic solvent has a mass fraction of 90-94% in the organic binder.

[0014] Furthermore, in the boron-aluminum paste, the organic solvent is at least five of the following: benzyl alcohol, diethyl phthalate, terpineol, butylcarbamate, butylcarbamate acetate, tributyl citrate, Span 85, and 12-ol ester.

[0015] Furthermore, in the boron-aluminum paste, the glass powder comprises 15-25% Bi2O3, 6-10% Al2O3, 10-15% Pb2O5, 12-29% ZnO, 15-25% Sb2O5, 6-10% V2O5, 9-25% TiO2, and 10-20% BaO by mass.

[0016] Furthermore, in the boron-aluminum paste, the boron powder is micron-sized boron powder.

[0017] This invention also proposes a method for preparing boron-aluminum paste for laser doping to form p-type doped regions in N-type IBC cells, comprising:

[0018] Aluminum powder, boron powder, organic binder, and glass powder are mixed to obtain a mixture;

[0019] After grinding the mixture, organic additives are added to obtain a boron-aluminum paste for laser doping to form the p-type doped region in an N-type IBC cell.

[0020] The present invention also proposes an N-type IBC battery, wherein the back side of the N-type IBC battery includes interdigitated n-type doped regions and p-type doped regions, and the p-type doped regions are prepared by laser doping after printing and sintering the above-mentioned boron-aluminum paste.

[0021] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0022] In this embodiment of the invention, the provided boron-aluminum paste comprises aluminum powder, silver powder, boron powder, glass powder, organic binder, and organic additives. By adding boron powder to the aluminum paste, directly printing it onto the n-type primary silicon region, and then performing high-temperature sintering and laser doping, a high-concentration boron doping of the n-type primary silicon region can be achieved to form a p-type doped region. This avoids the side effects of using traditional tubular boron sources for doping, ensuring the conversion efficiency of the battery. Therefore, it solves the problem that the existing methods for forming the p-type doped region in N-type IBC batteries are complex and have many side effects, easily affecting the photoelectric conversion efficiency of the battery.

[0023] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0024] Figure 1 This is a flowchart of the preparation method of boron-aluminum paste provided in the embodiments of the present invention. Detailed Implementation

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] The applicant of this invention has discovered that the current N-type IBC technology route simply prepares high-quality interdigitated P-regions and N-regions on the back of the battery. It uses tubular boron diffusion on the original silicon wafer to form the P+ region, which is not only complex and costly, but also results in a large emitter contact resistance in the formed p-type doped region, leading to a low open-circuit voltage and poor photoelectric conversion efficiency of the battery.

[0027] To address the aforementioned problems, this invention provides a boron-aluminum paste for laser doping to form p-type doped regions in N-type IBC cells. The components of the boron-aluminum paste include aluminum powder, silver powder, boron powder, glass powder, organic binder, and organic additives.

[0028] Aluminum powder is the main component, mainly replacing the P+ emitter of the battery, while boron powder can diffuse into the silicon interior for heavy doping during high-temperature sintering, which is beneficial to improving the contact performance of the slurry, reducing the reaction contact surface between aluminum and silicon, reducing the contact resistivity between the positive electrode grid and the battery, thereby improving the battery filling and battery efficiency.

[0029] Among them, glass powder is an inorganic binder that melts into a liquid state under high temperature conditions and solidifies when cooled, thus playing a bonding role; organic binders can ensure the overall bonding effect; and organic additives can reduce the overall viscosity of the silver paste.

[0030] Therefore, the boron-aluminum paste provided in this embodiment of the invention can form a highly concentrated p-type doped region after sintering and laser doping, which provides better contact with the solar cell itself and has a lower series resistance than traditional aluminum paste. This avoids the side effects of using traditional tubular boron sources for doping, thus ensuring the conversion efficiency of the cell. It solves the problem that the existing N-type IBC cell p-type doped region formation process is complex and has many side effects, which can easily affect the photoelectric conversion efficiency of the cell.

[0031] Optionally, in one embodiment, the boron-aluminum paste contains, by mass percentage, 0.3-0.8% organic additives, 0.5-1% boron powder, 74-80% aluminum powder, 16.7-24.2% organic binder, and 1-1.5% glass powder. The boron-aluminum paste provided in this embodiment has a low aluminum content, resulting in a smaller proportion of aluminum in the aluminum-silicon alloy during formation. Therefore, during cooling, excess aluminum will not diffuse into the PN junction region, creating a metal composite region. Simultaneously, the high boron content allows for the formation of a highly concentrated p-type doped region through a combination of sintering and laser doping.

[0032] For example, in the boron-aluminum paste, the mass fractions of organic additives, boron powder, aluminum powder, organic binder, and glass powder are 0.5%, 0.5%, 76%, 21.5%, and 1.5%, respectively.

[0033] For example, in the boron-aluminum paste, the mass fractions of organic additives, boron powder, aluminum powder, organic binder and glass powder are 0.8%, 1%, 80%, 16.7% and 1.5%, respectively.

[0034] For example, in the boron-aluminum paste, the mass fractions of organic additives, boron powder, aluminum powder, organic binder, and glass powder are 0.3%, 0.5%, 74%, 24.2%, and 1%, respectively.

[0035] For example, in the boron-aluminum paste, the mass fractions of organic additives, boron powder, aluminum powder, organic binder and glass powder are 0.5%, 0.8%, 76%, 21.5% and 1.2%, respectively.

[0036] Optionally, in one embodiment, the boron powder comprises elemental boron.

[0037] Optionally, in one specific embodiment, the boron powder comprises micron-sized elemental boron. By adding this micron-sized elemental boron, the boron powder can rapidly diffuse into the silicon interior for heavy doping during high-temperature sintering, which is beneficial for improving the contact performance of the slurry.

[0038] Optionally, in one specific embodiment, the boron powder is micron-sized boron powder with a purity of 2 nines.

[0039] Alternatively, in another embodiment, the above includes a boron-aluminum alloy. By adding this micron-sized boron-aluminum alloy powder, the boron-aluminum paste can quickly form a good alloy with silicon at a lower sintering temperature, reducing the contact resistivity between the front-side boron-aluminum grid and the n-type primary silicon wafer.

[0040] Optionally, in one embodiment, the aluminum powder comprises 85-90% by mass of micron-sized spherical aluminum powder and 10-15% by mass of nano-sized spherical aluminum powder. The nano-sized spherical aluminum powder fills and penetrates into these gaps between the micron-sized aluminum powder particles, as there are gaps between them.

[0041] Optionally, in one specific embodiment, the aluminum powder includes micron-sized spherical aluminum powder with a purity of three nines, a mass fraction of 85-90%, and a D50 of 5-6 μm, and nano-spherical aluminum powder with a purity of three nines, a mass fraction of 10-15%, and a D50 of 7-9 nm.

[0042] Optionally, in one embodiment, the organic additives include two or more of the following: fatty alcohol ether phosphate, aluminate coupling agent, silane coupling agent, zirconium aluminate coupling agent, lauryl phosphate, silicone oil, diester, lauryl phosphate, DIG655, BYK110, and BYK105.

[0043] In the boron-aluminum paste provided in the embodiments of the present invention, the above-mentioned organic binder includes a polymer resin and an organic solvent; wherein, the polymer resin is dissolved in the organic solvent, so that the organic solvent can act as an organic binder, that is, the paste can act as a binder for powder after drying.

[0044] Optionally, in one embodiment, the polymer in the organic adhesive has a mass fraction of 10-15%, and the organic solvent in the organic adhesive has a mass fraction of 85-90%.

[0045] Optionally, in one embodiment, the above-mentioned polymer is one or more of ethyl cellulose-N20, ethyl cellulose N-50, and ethyl cellulose-N100;

[0046] The aforementioned organic solvents include at least five of the following: benzyl alcohol, diethyl phthalate, terpineol, butylcarbiol, butylcarbiol acetate, tributyl citrate, Span 85, and 12-ol ester.

[0047] Optionally, in one embodiment, the glass powder comprises, by mass fraction, 15-25% Bi2O3, 6-10% Al2O3, 10-15% Pb2O5, 12-29% ZnO, 15-25% Sb2O5, 6-10% V2O5, 9-25% TiO2, and 10-20% BaO. The D50 of the glass powder is 1.5-2 μm. If the D50 is less than 1.5 μm, the glass activity is too high, while if the D50 is greater than 2 μm, the glass activity is too low.

[0048] Among them, Bi2O3 forms the main network structure, ZnO can break the network structure and promote glass crystallization, Sb2O5 is used to clarify and homogenize the glass melt, Al2O3 can adjust the stability of the glass and increase its viscosity, Pb2O5 reacts with silicon nitride to produce lead, nitrogen and silicon dioxide, V2O5 and TiO2 can assist Pb2O5 and silicon nitride in their reaction, and BaO is used for local crystallization.

[0049] For example, by mass fraction, the glass powder comprises 15% Bi2O3, 10% Al2O3, 10% Pb2O5, 15% ZnO, 15% Sb2O5, 15% V2O5, 15% TiO2, and 5% BaO.

[0050] For example, by mass fraction, the glass powder comprises 25% Bi2O3, 6% Al2O3, 10% Pb2O5, 5% ZnO, 15% Sb2O5, 15% V2O5, 15% TiO2, and 9% BaO.

[0051] For example, by mass fraction, the glass powder comprises 22% Bi2O3, 6% Al2O3, 12% Pb2O5, 10% ZnO, 18% Sb2O5, 7% V2O5, 15% TiO2, and 10% BaO.

[0052] This invention also provides a method for preparing boron-aluminum paste for laser doping to form p-type doped regions in N-type IBC cells, wherein, as... Figure 1 As shown, steps 101 to 102 are included:

[0053] Step 101: Mix aluminum powder, boron powder, organic binder and glass powder to obtain a mixture;

[0054] Step 102: After grinding the mixture, add organic additives to obtain boron-aluminum paste for laser doping to form the p-type doped region in an N-type IBC cell.

[0055] In step 101 above, 74-80% of aluminum powder, 0.5-1% of boron powder, 16.7-24.2% of organic binder, and 1-1.5% of glass powder, accounting for the total mass of raw materials, are weighed and mixed, and dispersed using a disperser to obtain the above mixture.

[0056] Optionally, in one embodiment, in step 101 above, the organic binder and boron powder are first mixed and dispersed using a disperser, then aluminum powder and glass powder are added and dispersed again using a disperser, and then ground to obtain the above mixture.

[0057] In step 102 above, the mixture is ground and then an organic additive accounting for 0.3 to 0.8% of the total mass of the raw materials is added. After high-speed dispersion, a boron-aluminum paste is obtained for laser doping to form the p-type doped region in an N-type IBC cell.

[0058] In this embodiment of the invention, by adding boron powder to aluminum paste and directly printing it onto the n-type primary silicon region, followed by high-temperature sintering and laser doping, a high-concentration boron doping of the n-type primary silicon region can be achieved to form a p-type doped region. This avoids the side effects of using traditional tubular boron sources for doping, ensuring the conversion efficiency of the battery. Therefore, it solves the problem that the existing methods for forming the p-type doped region of N-type IBC batteries are complex and have many side effects, which can easily affect the photoelectric conversion efficiency of the battery.

[0059] Optionally, in the preparation method provided in this embodiment of the invention, the boron powder is a micron-sized boron-aluminum alloy and / or micron-sized elemental boron. Micron-sized boron-aluminum alloy and micron-sized elemental boron have the characteristics of high tap density, low oxygen content, and high activity. By adding this micron-sized boron-aluminum alloy powder and / or micron-sized elemental boron, the silver-aluminum paste can quickly form a good alloy with silicon under relatively low sintering temperature conditions, reducing the contact resistivity between the front-side silver-aluminum grid and the battery.

[0060] Optionally, in the preparation method provided in the embodiments of the present invention, the organic additive includes two or more of the following: fatty alcohol ether phosphate, aluminate coupling agent, silane coupling agent, zirconium aluminate coupling agent, lauryl phosphate, silicone oil, diester, and lauryl phosphate.

[0061] Optionally, in the preparation method provided in the embodiments of the present invention, the aluminum powder includes 85-90% by mass micron-sized spherical aluminum powder and 10-15% by mass nano-sized spherical aluminum powder.

[0062] Optionally, in the preparation method provided in the embodiments of the present invention, the organic binder includes a polymer resin and an organic solvent;

[0063] The polymer in the organic binder has a mass fraction of 6-10%;

[0064] The organic solvent has a mass fraction of 90-94% in the organic binder.

[0065] Optionally, in the preparation method provided in the embodiments of the present invention, the organic solvent is at least five of the following: benzyl alcohol, diethyl phthalate, terpineol, butylcarbiol, butylcarbiol acetate, tributyl citrate, Span 85, and 12-ol ester.

[0066] Optionally, in the preparation method provided in the embodiments of the present invention, the glass powder includes 15-25% Bi2O3, 6-10% Al2O3, 10-15% Pb2O5, 12-23% ZnO, 15-25% Sb2O5, 6-10% V2O5, 15-25% TiO2, and 10-20% BaO by mass.

[0067] The present invention also proposes an N-type IBC battery, wherein the back side of the N-type IBC battery includes interdigitated n-type doped regions and p-type doped regions, and the p-type doped regions are prepared by laser doping after printing and sintering the above-mentioned boron-aluminum paste.

[0068] The steps for fabricating an N-type IBC battery using the boron-aluminum paste provided in this embodiment of the invention are as follows:

[0069] (1) After forming a silicon oxide layer and a phosphorus-doped polycrystalline silicon layer sequentially on the back side of an N-type silicon wafer, laser grooving is performed on the back side of the silicon wafer to form an interdigitated n-type doped region and an n-type primary silicon region.

[0070] (2) Print boron-aluminum paste on the first region within the n-type primary silicon region and sinter at high temperature to form a boron-aluminum coating, and then perform laser doping treatment on the first region.

[0071] (3) After laser doping treatment, passivation film and antireflection film are formed on both sides of the silicon wafer;

[0072] (4) After forming the antireflection film, a positive gate line that contacts the first region and a negative gate line that contacts the n-type doped region are formed on the back side of the silicon wafer to obtain an N-type IBC cell.

[0073] The present invention will be described in detail below through embodiments.

[0074] Example 1

[0075] (1) Provide boron aluminum paste a1: By weight, boron aluminum paste a1 is composed of 0.5 parts organic additives, 0.5 parts boron powder, 76 parts aluminum powder, 21.5 parts organic binder and 1.5 parts glass powder;

[0076] The organic additives are lauryl phosphate and BYK110; the boron powder is micron-sized elemental boron with a purity of 99.99%; the aluminum powder includes micron-sized spherical aluminum powder with a purity of 99.99% and a mass fraction of 88%, and nano-spherical aluminum powder with a purity of 99.99% and a mass fraction of 12%; the organic binder includes 6% ethyl cellulose-N100 and 94% organic solvent, which consists of benzyl alcohol, terpineol, butylcarbiol, butylcarbiol acetate and Span 85; the glass powder is obtained by sintering and pulverizing 17% Bi2O3, 8% Al2O3, 12% Pb2O5, 15% ZnO, 20% Sb2O5, 6% V2O5, 12% TiO2 and 10% BaO, with a D50 of 1.5-2 μm.

[0077] (2) The above boron-aluminum paste was screen-printed on a single crystal N-type silicon wafer with a specification of 182mm×182mm to form an aluminum fine grid. It was then sintered in a sintering furnace at a peak temperature of 768℃. After sintering, the aluminum fine grid was ablated with a low-power laser and then doped. After cleaning with hydrochloric acid, the sheet resistance was tested to be 105Ω and the concentration of ECV was tested to be 9E18, which met the requirements of boron ablation.

[0078] Example 2

[0079] (1) Provide boron aluminum paste a2: by weight, boron aluminum paste a2 is composed of 0.8 parts organic additives, 1 part boron powder, 80 parts aluminum powder, 16.7 parts organic binder and 1.5 parts glass powder;

[0080] The organic additives are lauryl phosphate and BYK105; the boron powder is micron-sized elemental boron with a purity of 99.99%; the aluminum powder includes micron-sized spherical aluminum powder with a purity of 99.99% and a mass fraction of 88%, and nano-spherical aluminum powder with a purity of 99.99% and a mass fraction of 12%; the organic binder includes 6% ethyl cellulose-N100 and 94% organic solvent, which consists of benzyl alcohol, terpineol, butylcarbiol, butylcarbiol acetate and Span 85; the glass powder is obtained by sintering and pulverizing 17% Bi2O3, 8% Al2O3, 12% Pb2O5, 15% ZnO, 20% Sb2O5, 6% V2O5, 12% TiO2 and 10% BaO, with a D50 of 1.5-2 μm.

[0081] (2) The above boron-aluminum paste was screen-printed on a single crystal N-type silicon wafer with a specification of 182mm×182mm using a 360-mesh screen to form an aluminum fine grid. The wafer was then sintered in a sintering furnace at a peak temperature of 772℃. After sintering, the aluminum fine grid was ablated using a low-power laser. The aluminum fine grid was then doped and cleaned with hydrochloric acid. The sheet resistance was tested to be 95Ω and the concentration of ECV was tested to be 1.05E19, which met the requirements of boron ablation.

[0082] Example 3

[0083] (1) Provide boron aluminum paste a3: by weight, boron aluminum paste a3 is composed of 0.3 parts organic additives, 0.5 parts boron powder, 74 parts aluminum powder, 24.2 parts organic binder and 1 part glass powder;

[0084] The organic additives are lauryl phosphate and BYK110; the boron powder is a boron-aluminum alloy; the aluminum powder includes micron-sized spherical aluminum powder with a purity of 99.99% and a mass fraction of 88%, and nano-spherical aluminum powder with a purity of 99.99% and a mass fraction of 12%; the organic binder includes 6% ethyl cellulose-N100 and 94% organic solvent, which consists of benzyl alcohol, terpineol, butylcarbiol, butylcarbiol acetate and Span 85; the glass powder is obtained by sintering and pulverizing 17% Bi2O3, 8% Al2O3, 12% Pb2O5, 15% ZnO, 20% Sb2O5, 6% V2O5, 12% TiO2 and 10% BaO, with a D50 of 1.5-2 μm.

[0085] (2) The above boron-aluminum paste was screen-printed on a single crystal N-type silicon wafer with a specification of 182mm×182mm to form an aluminum fine grid. It was then sintered in a sintering furnace at a peak temperature of 772℃. After sintering, the aluminum fine grid was ablated with a low-power laser and then doped. After cleaning with hydrochloric acid, the sheet resistance was tested to be 40Ω and the concentration of ECV was tested to be 1E19, which met the requirements of boron ablation.

[0086] Example 4

[0087] (1) Provide boron aluminum paste a4: by weight, boron aluminum paste a4 is composed of 0.5 parts organic additives, 0.8 parts boron powder, 76 parts aluminum powder, 21.5 parts organic binder and 1.2 parts glass powder;

[0088] The organic additives are lauryl phosphate and BYK110; the boron powder is micron-sized elemental boron with a purity of 99.99%; the aluminum powder includes micron-sized spherical aluminum powder with a purity of 99.99% and a mass fraction of 88%, and nano-spherical aluminum powder with a purity of 99.99% and a mass fraction of 12%; the organic binder includes 6% ethyl cellulose-N100 and 94% organic solvent, which consists of benzyl alcohol, terpineol, butylcarbiol, butylcarbiol acetate and Span 85; the glass powder is obtained by sintering and pulverizing 17% Bi2O3, 8% Al2O3, 12% Pb2O5, 15% ZnO, 20% Sb2O5, 6% V2O5, 12% TiO2 and 10% BaO, with a D50 of 1.5-2 μm.

[0089] (2) The above boron-aluminum paste was screen-printed on a single crystal N-type silicon wafer with a specification of 182mm×182mm to form an aluminum fine grid. It was then sintered in a sintering furnace at a peak temperature of 776℃. After sintering, the aluminum fine grid was ablated with a low-power laser and then doped. After cleaning with hydrochloric acid, the sheet resistance was tested to be 42Ω and the concentration of ECV was tested to be 1.85E18, which met the boron ablation requirements.

[0090] Example 5

[0091] (1) Provide boron aluminum paste a5: By weight, boron aluminum paste a4 is composed of 0.5 parts organic additives, 0.8 parts boron powder, 76 parts aluminum powder, 21.5 parts organic binder and 1.2 parts glass powder;

[0092] The organic additives are lauryl phosphate and BYK110; the boron powder is micron-sized elemental boron with a purity of 99.99%; the aluminum powder includes micron-sized spherical aluminum powder with a purity of 99.99% and a mass fraction of 88%, and nano-spherical aluminum powder with a purity of 99.99% and a mass fraction of 12%; the organic binder includes 6% ethyl cellulose-N100 and 94% organic solvent, which consists of benzyl alcohol, terpineol, butylcarbiol, butylcarbiol acetate and Span 85; the glass powder is obtained by sintering and pulverizing 15% Bi2O3, 6% Al2O3, 10% Pb2O5, 29% ZnO, 15% Sb2O5, 6% V2O5, 9% TiO2 and 10% BaO, with a D50 of 1.5-2 μm.

[0093] (2) The above boron-aluminum paste was screen-printed on a single crystal N-type silicon wafer with a specification of 182mm×182mm to form an aluminum fine grid. It was then sintered in a sintering furnace at a peak temperature of 774℃. After sintering, the aluminum fine grid was ablated with a low-power laser and then doped. After cleaning with hydrochloric acid, the sheet resistance was tested to be 42Ω and the concentration of ECV was tested to be 1.1E19, which met the boron ablation requirements.

[0094] As can be seen from Examples 1 to 5, after printing the boron-aluminum paste from the embodiments of the present invention onto the n-type primary silicon region, high-temperature sintering and laser doping can be performed to achieve high-concentration boron doping of the n-type primary silicon region to form a p-type doped region.

[0095] In summary, in this embodiment, by adding boron powder to the aluminum paste, directly printing it onto the n-type primary silicon region, and then performing high-temperature sintering and laser doping, a high-concentration boron doping of the n-type primary silicon region can be achieved to form a p-type doped region. This avoids the side effects of using traditional tubular boron sources for doping, ensuring the conversion efficiency of the battery. Therefore, it solves the problem that the existing methods for forming the p-type doped region of N-type IBC batteries are complex and have many side effects, which can easily affect the photoelectric conversion efficiency of the battery.

[0096] 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.

[0097] The foregoing has provided a detailed description of the boron-aluminum paste, N-type IBC battery, and its preparation method provided by the present invention. 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, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A boron-aluminum paste, characterized in that, The boron-aluminum paste used for laser doping to form p-type doped regions in N-type IBC solar cells comprises aluminum powder, silver powder, boron powder, glass powder, organic binder, and organic additives; the aluminum powder accounts for 74-80% by mass; and the glass powder accounts for 1-1.5% by mass. The glass powder includes 15-25% Bi2O by mass. 3、 Al2O3 with a mass fraction of 6-10%, Pb2O5 with a mass fraction of 10-15%, ZnO with a mass fraction of 12-29%, Sb2O5 with a mass fraction of 15-25%, V2O5 with a mass fraction of 6-10%, TiO2 with a mass fraction of 9-25%, and BaO with a mass fraction of 10-20%.

2. The boron-aluminum paste according to claim 1, characterized in that, The organic additive has a mass percentage of 0.3-0.8%; the boron powder has a mass percentage of 0.5-1%; and the organic binder has a mass percentage of 16.7-24.2%.

3. The boron-aluminum paste according to claim 1, characterized in that, The boron powder includes elemental boron and / or boron-aluminum alloy.

4. The boron-aluminum paste according to claim 1, characterized in that, The boron powder is micron-sized boron powder.

5. The boron-aluminum paste according to claim 1, characterized in that, The organic additives include two or more of the following: fatty alcohol ether phosphate, aluminate coupling agent, silane coupling agent, zirconium aluminate coupling agent, and lauryl phosphate.

6. The boron-aluminum paste according to claim 1, characterized in that, The aluminum powder comprises 85-90% by weight micron-sized spherical aluminum powder and 10-15% by weight nano-sized spherical aluminum powder.

7. The boron-aluminum paste according to claim 1, characterized in that, The organic adhesive comprises a polymer resin and an organic solvent; The polymer in the organic adhesive has a mass fraction of 6-10%; The organic solvent has a mass fraction of 90-94% in the organic adhesive.

8. The boron-aluminum paste according to claim 1, characterized in that, The organic solvent is at least five of the following: benzyl alcohol, diethyl phthalate, terpineol, butylcarbamate, butylcarbamate acetate, tributyl citrate, Span 85, and ester twelve.

9. An N-type IBC battery, characterized in that, The back side of the N-type IBC cell includes interdigitated n-type doped regions and p-type doped regions, wherein the p-type doped regions are prepared by laser doping after printing and sintering the boron-aluminum paste as described in any one of claims 1 to 8.

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