阅读说明：本技术 背场掺杂用硼铝浆、太阳电池及其制备方法 (Boron-aluminum paste for back field doping, solar cell and preparation method thereof ) 是由 王璞 苏荣 陈坤 王岚 李书森 李忠涌 黄艳琴 于 2020-12-01 设计创作，主要内容包括：本申请涉及太阳电池领域,具体而言,涉及一种背场掺杂用硼铝浆、太阳电池及其制备方法。一种背场掺杂用硼铝浆,按照质量分数计,所述背场掺杂用硼铝浆包括：35％～55％的硼源,15％～25％的铝源,15％～30％的硅源以及20～40％的有机载体。上述背场掺杂用硼铝浆在掺杂后会在硅衬底上形成铝硅合金,降低了掺杂层与背银电极导出层接触的空洞,降低接触电阻,进而降低了电池的串联电阻,增加了太阳电池的填充因子,提高太阳电池的开路电压,最终提升太阳电池的效率。(The application relates to the field of solar cells, in particular to boron-aluminum paste for back surface field doping, a solar cell and a preparation method thereof. The boron-aluminum paste for back field doping comprises the following components in percentage by mass: 35-55% of boron source, 15-25% of aluminum source, 15-30% of silicon source and 20-40% of organic carrier. The boron-aluminum paste for back surface field doping can form aluminum-silicon alloy on the silicon substrate after doping, so that a cavity between the doping layer and the back silver electrode lead-out layer is reduced, the contact resistance is reduced, the series resistance of the battery is further reduced, the filling factor of the solar battery is increased, the open-circuit voltage of the solar battery is improved, and the efficiency of the solar battery is finally improved.)

1. The boron-aluminum paste for back field doping is characterized by comprising the following components in percentage by mass:

35-55% of boron source, 15-25% of aluminum source, 15-30% of silicon source and 20-40% of organic carrier.

2. The boron-aluminum paste for back-field doping according to claim 1,

the boron source is trimethyl borane, and the silicon source is ethylene (chloromethyl) dimethoxysilane; the aluminum source is aluminum chloride.

3. The boron aluminum paste for back-field doping according to claim 1 or 2,

the organic carrier comprises isopropyl carbinol, tetraethyl silicate and glass powder.

4. A method for manufacturing a solar cell, comprising:

a back surface passivation film is arranged on the back surface of the P-type silicon substrate;

setting a grouting groove penetrating through the back passivation film;

filling the boron-aluminum paste for back surface field doping according to any one of claims 1 to 3 in the grouting tank, and forming a boron-aluminum paste doping layer on the P-type silicon substrate.

5. The method for manufacturing a solar cell according to claim 4,

after the step of filling the boron-aluminum slurry for back field doping in the grouting tank, forming the boron-aluminum slurry doping layer by using laser energy;

optionally, the laser has a square spot with a spot size of 20 × 20 μm²～30×30μm²The laser frequency is 80 KHz-100 KHz.

6. The method for manufacturing a solar cell according to claim 4 or 5,

the back passivation film comprises a back silicon oxide passivation layer, a nickel oxide field passivation layer and a back silicon nitride protection layer which are sequentially outward along the back of the P-type silicon substrate;

optionally, preparing the nickel oxide field passivation layer by using ALD (atomic layer deposition) equipment, wherein the flow ratio of nickel acetate to oxygen is (2-4): 1, and the reaction temperature is 180-280 ℃;

optionally, the thickness of the nickel oxide field passivation layer is 20nm to 50 nm.

7. The method for manufacturing a solar cell according to claim 6,

the thickness of the back surface silicon oxide passivation layer is 1 nm-5 nm;

optionally, the back silicon nitride protective layer, SiH, is made by PECVD equipment₄And NH₃The flow ratio of (2-5) to (1);

optionally, the thickness of the back side silicon oxide passivation layer is 100nm to 150 nm.

8. The method for manufacturing a solar cell according to claim 4 or 5,

before the setting up the grout groove that runs through the passive film of back, still include:

arranging a front passivation film on the front surface of the P-type silicon substrate;

the front passivation film comprises a front silicon oxide chemical passivation layer and a front silicon nitride antireflection layer which are sequentially arranged outwards along the front surface of the P-type silicon substrate;

wherein the thickness of the front silicon nitride antireflection layer is 70-100 nm;

optionally, the front silicon nitride antireflection layer, SiH, is manufactured by adopting a PECVD apparatus₄And NH₃The flow ratio of (2-5) to (1);

optionally, the thickness of the front-side silicon oxide chemical passivation layer is 1nm to 5 nm.

9. The method for manufacturing a solar cell according to claim 4 or 5,

the P-type silicon substrate is boron-doped monocrystalline silicon or boron-doped polycrystalline silicon.

10. A solar cell produced by the method for producing a solar cell according to any one of claims 4 to 9.

Technical Field

The application relates to the field of solar cells, in particular to boron-aluminum paste for back surface field doping, a solar cell and a preparation method thereof.

Background

Among the mass-produced solar cells, silicon-based solar cells have always occupied the monopoly of the market. Compared with other solar cell structures, the Passivated Emitter Rear Contact and reactor Contact (PERC) cell has lower cost increase but obviously improved efficiency, and becomes a hotspot of the industrialized research of the high-efficiency crystalline silicon solar cell at the present stage.

The present application is directed to increasing the open circuit voltage of a solar cell.

Disclosure of Invention

An object of the embodiments of the present application is to provide a boron aluminum paste for back field doping, a solar cell and a method for manufacturing the same, which aim to improve an open-circuit voltage of the solar cell.

The application provides in a first aspect a boron-aluminum paste for back-field doping, which comprises, in mass fraction:

35-55% of boron source, 15-25% of aluminum source, 15-30% of silicon source and 20-40% of organic carrier.

After the boron-aluminum paste for back field doping is doped, aluminum-silicon alloy is formed on the silicon substrate, so that a cavity between the doped layer and the back silver electrode lead-out layer is reduced, the contact resistance is reduced, the series resistance of the cell is further reduced, and the filling factor of the solar cell is increased; the boron-aluminum paste for back field doping contains 35% -55% of boron source, and compared with the boron-aluminum paste with the boron source content being less than 35% and more than 55%, the boron-aluminum paste provided by the application can obviously improve open-circuit voltage, so that the efficiency of the solar cell is finally improved.

In some embodiments of the first aspect of the present application, the boron source is trimethylborane and the silicon source is ethylene (chloromethyl) dimethoxysilane; the aluminum source is aluminum chloride.

In some embodiments of the first aspect of the present application, the organic vehicle comprises isopropyl carbinol, tetraethyl silicate, and glass frit.

In a second aspect, the present application provides a method for manufacturing a solar cell, including:

a back surface passivation film is arranged on the back surface of the P-type silicon substrate;

setting a grouting groove penetrating through the back passivation film;

and filling the boron-aluminum slurry for back field doping in the grouting groove, and forming a boron-aluminum slurry doping layer on the P-type silicon substrate.

In some embodiments of the second aspect of the present application, after the step of filling the boron-aluminum paste for back-field doping in the slurry tank, a laser energy is used to form the boron-aluminum paste doping layer;

optionally, the laser has a square spot with a spot size of 20 × 20 μm²～30×30μm²The laser frequency is 80 KHz-100 KHz.

The boron-aluminum slurry for back field doping forms a P + + layer in the back field at the grouting groove under the action of laser, so that the carrier concentration of the back field is increased, the carrier recombination of a laser grooving area is reduced, and the open-circuit voltage of the solar cell is improved. Secondly, the boron-aluminum paste forms aluminum-silicon alloy under the laser doping condition, so that the cavity of the laser doping layer in contact with the back silver electrode lead-out layer is reduced, the contact resistance is reduced, the series resistance of the cell is further reduced, the filling factor of the solar cell is increased, and the efficiency of the solar cell is finally improved.

In some embodiments of the second aspect of the present application, the back passivation film comprises a back silicon oxide passivation layer, a nickel oxide field passivation layer and a back silicon nitride protection layer sequentially outward along the back of the P-type silicon substrate;

optionally, preparing the nickel oxide field passivation layer by using ALD (atomic layer deposition) equipment, wherein the flow ratio of nickel acetate to oxygen is (2-4): 1, and the reaction temperature is 180-280 ℃;

optionally, the thickness of the nickel oxide field passivation layer is 20nm to 50 nm.

In some embodiments of the second aspect of the present application, the back side silicon oxide passivation layer has a thickness of 1nm to 5 nm;

optionally, the back silicon nitride protective layer, SiH, is made by PECVD equipment₄And NH₃The flow ratio of (2-5) to (1);

optionally, the thickness of the back side silicon oxide passivation layer is 100nm to 150 nm.

In some embodiments of the second aspect of the present application, before the providing the grouting groove penetrating the rear passivation film, the method further includes:

arranging a front passivation film on the front surface of the P-type silicon substrate;

the front passivation film comprises a front silicon oxide chemical passivation layer and a front silicon nitride antireflection layer which are sequentially arranged outwards along the front surface of the P-type silicon substrate;

wherein the thickness of the front silicon nitride antireflection layer is 70-100 nm;

optionally, the front silicon nitride antireflection layer, SiH, is manufactured by adopting a PECVD apparatus₄And NH₃The flow ratio of (2-5) to (1);

optionally, the thickness of the front-side silicon oxide chemical passivation layer is 1nm to 5 nm.

In some embodiments of the third aspect of the present application, the P-type silicon substrate is boron-doped monocrystalline silicon or boron-doped polycrystalline silicon.

In a third aspect, the present application provides a solar cell manufactured by the method for manufacturing a solar cell provided in the second aspect.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

Fig. 1 shows a schematic structural diagram of a solar cell.

Fig. 2 shows schematic diagrams of open circuit voltages of the solar cells provided in example 1 and comparative example 1.

Icon: 001-a metal gate line electrode layer; 002-front side silicon nitride antireflection layer; 003-front side silicon oxide chemical passivation layer; a 004-N type phosphorus source doping layer; 005-P type silicon substrate; 006-boron aluminum paste doping layer; 007-back side silicon oxide passivation layer; 008-a nickel oxide field passivation layer; 009-a back side silicon nitride protective layer; 010-back metal grid line electrode layer.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The boron aluminum paste for back field doping, the solar cell, and the method for manufacturing the same in the embodiments of the present application are specifically described below.

The boron-aluminum paste for back field doping comprises the following components in percentage by mass:

35-55% of boron source, 15-25% of aluminum source, 15-30% of silicon source and 20-40% of organic carrier.

After research, the inventor finds that aluminum-silicon alloy is formed on the silicon substrate after the boron-aluminum paste for back surface field doping is doped, so that a cavity between the doped layer and the back silver electrode lead-out layer is reduced, the contact resistance is reduced, the series resistance of the cell is further reduced, the filling factor of the solar cell is increased, and the efficiency of the solar cell is finally improved.

Illustratively, the boron source may be 35%, 36%, 39%, 40%, 42%, 45%, 48%, 50%, 52%, 55%, or the like in the boron aluminum paste for back-field doping. For example, the boron source may be trimethylborane, diborane, or the like. In this embodiment, the boron source is selected from trimethylborane.

The content of the boron source is not easy to be too high, if the content is too high or too low, the open-circuit voltage cannot be improved, and the open-circuit voltage of the solar cell can be improved by 35-55% of the boron source.

If the content of boron source is less than 35%, for example, about 10%; the open-circuit voltage of the solar cell is not obviously improved; if the content of the boron source is higher than 55%, the open-circuit voltage of the solar cell is not obviously improved.

The mass ratio of the aluminum source in the boron-aluminum slurry for back-field doping can be 15%, 16%, 17%, 18%, 20%, 23%, 25% or the like. The aluminum source can be aluminum chloride and Al₂S₃、NaAlO₂And so on. In this embodiment, the aluminum source is aluminum chloride.

If the content of the aluminum source is lower, the filling performance of the boron-aluminum paste is poor, and the series resistance is higher. If the aluminum source content is high, voids may be formed in the aluminum-silicon alloy, resulting in a high series resistance.

The mass ratio of the silicon source in the boron-aluminum slurry for back field doping can be 15%, 18%, 20%, 25%, 29%, 30% or the like. The silicon source has the function of lubricating the boron-aluminum paste and the substrate, and is beneficial to doping of the boron source.

The mass ratio of the organic carrier in the boron-aluminum paste for back field doping may be 20%, 22%, 25%, 30%, 32%, 36%, 39%, 40%, or the like.

As an example, the organic vehicle includes isopropyl carbinol, tetraethyl silicate, and glass frit; the mass ratio of the isopropyl methanol to the tetraethyl silicate to the glass powder is 1:1: 1.

In some embodiments of the present application, the boron-aluminum paste for back-field doping may further include other substances such as additives. For example, can include terpineol, which can prevent the slurry from setting and improve screen life.

The application also provides a preparation method of the solar cell, which is used for preparing the boron-aluminum paste doping layer of the solar cell by applying the boron-aluminum paste for back field doping. The preparation method is mainly used for preparing the solar cell with the structure shown in figure 1. Fig. 1 shows a schematic structural diagram of a solar cell provided in an embodiment of the present application.

Referring to fig. 1, the preparation method mainly includes the following steps:

carrying out texturing, diffusion and laser SE doping treatment on a P-type silicon substrate 005 and then polishing the back surface of the P-type silicon substrate;

in the embodiment of the present application, the P-type silicon substrate 005 is boron-doped single crystal silicon or boron-doped polycrystalline silicon, has a resistivity of 0.3 Ω · cm to 1.5 Ω · cm, and has a substrate thickness of 150 μm to 200 μm. Doping a phosphorus source on the front surface of the P-type silicon substrate 005 to prepare a PN junction; doping concentration of N-type phosphorus source doping layer 004 is 10¹⁶～10²⁰atoms/cm³The thickness of the N-type phosphorus source doped layer 004 is 300 nm-800 nm.

After the N-type phosphorus source doped layer 004 is prepared, HNO is carried out₃And the solution and the HF solution are subjected to edge etching to eliminate phosphorus sources diffused at the edges, so that the electric leakage of the solar cell is avoided.

A back passivation film is provided on the back surface of the P-type silicon substrate 005; preparing a front passivation film on the front surface of the P-type silicon substrate 005; it should be noted that, in the present application, there is no precedence relationship between disposing the back passivation film on the back surface of the P-type silicon substrate 005 and preparing the front passivation film on the front surface of the P-type silicon substrate 005; in the present application, the back passivation film may be prepared first, or the front passivation film may be prepared first.

As an example, a method of producing the front surface passivation film is shown below:

the front passivation film includes a front silicon oxide chemical passivation layer 003 and a front silicon nitride anti-reflective layer 002 in this order from the front of the P-type silicon substrate 005 outward. An N-type phosphorus source doped layer 004 is located on the inside of the front side silicon oxide chemical passivation layer 003.

The front side silicon oxide chemical passivation layer 003 is prepared by dry oxygen oxidation, and accordingly, the front side silicon oxide chemical passivation layer 003 is prepared, while the back side silicon oxide passivation layer 007 is also prepared accordingly. The parameters of dry oxygen oxidation are as follows:

introducing dry oxygen, wherein the oxygen flow is 5L/min-10L/min, the temperature is 800-900 ℃, the preparation time is 20-30 min, and the thickness is 1-5 nm (for example, 1nm, 2nm, 3nm, 4nm, 5 nm). And the dangling bonds on the surface of the silicon wafer are saturated by oxygen atoms, so that the interface defect state density is reduced.

The front silicon nitride antireflection layer 002 is prepared by PECVD, and SiH is used as a silicon source₄Gas, nitrogenThe source is ammonia (NH)₃)，SiH₄：NH₃The flow ratio (2 to 4):1, and the front silicon nitride antireflection layer 002 may have a thickness of 70nm to 100nm (for example, 70nm, 72nm, 75nm, 80nm, 86nm, 94nm, 100nm), and a refractive index n of 2.0 to 2.2.

After the front silicon nitride antireflection layer 002 is prepared, silver paste is screen-printed on the surface of the front silicon nitride antireflection layer 002 to prepare a front current-carrying collection metal grid line electrode layer 001, and the thickness of the metal grid line electrode layer 001 is 30-100 micrometers.

As an example, a method of preparing the back passivation film is shown below:

the back passivation film includes a back silicon oxide passivation layer 007, a nickel oxide field passivation layer 008, and a back silicon nitride protection layer 009 sequentially outward along the back of the P-type silicon substrate 005.

The back silicon oxide passivation layer 007 is formed by dry oxygen oxidation and the method of forming is described above for the front silicon oxide chemical passivation layer 003.

The nickel oxide field passivation layer 008 is prepared by using ALD (atomic layer deposition) deposition equipment, wherein a nickel source is nickel acetate, the flow ratio of the nickel acetate to oxygen is (2-4): 1, the reaction temperature is 180-280 ℃, and the thickness of the nickel oxide field passivation layer 008 is 20-50 nm (for example, 20nm, 22nm, 27nm, 30nm, 36nm, 39nm, 46nm or 50 nm).

After the nickel oxide field passivation layer 008 is prepared, the back silicon nitride protective layer 009 is prepared by adopting PECVD, and the silicon source is SiH₄The nitrogen source is ammonia (NH)₃)，SiH₄：NH₃The flow ratio (3-5) is 1, and the thickness of the back silicon nitride protective layer 009 is 100 nm-150 nm (for example, 100nm, 108nm, 114nm, 120nm, 132nm, 140nm, 147nm, or 150 nm).

After the preparation of the back passivation film is finished, a grouting groove penetrating through the back passivation film is arranged; and (4) grooving by adopting laser to form a grouting groove.

Then, filling the grouting groove with the boron-aluminum paste for back field doping, for example, printing the boron-aluminum paste for back field doping at the aligned position by screen printing; after filling, a boron-aluminum plasma doped layer 006 is formed on the P-type silicon substrate 005.

Illustratively, the boron aluminum paste doping layer 006 may be formed by sintering, or laser energy may be irradiated to form the boron aluminum paste doping layer 006.

In the present application, the laser spot is square and the spot size is 20X 20 μm²～30×30μm²The laser frequency is 80 KHz-100 KHz.

The square laser spot and the laser energy are as above, and a heavily doped P + + back field is formed in the boron-aluminum slurry doping layer 006, so that the junction depth of the high and low junctions of the back field is promoted, and the collection of carriers of the back field is facilitated.

Alternatively, in some other embodiments of the present application, the laser spot may also be a circular spot.

After the boron-aluminum slurry doping layer 006 is prepared, a back metal grid line electrode layer 010 is prepared through screen printing slurry, and the back metal grid line electrode layer 010 is used for collecting battery back field carriers.

In the embodiment of the present application, the solar cell may be a double-sided cell or a single-sided cell. For the embodiment that the solar cell is a double-sided cell, the back metal grid line electrode layer 010 is prepared by screen printing silver paste; for the embodiment where the solar cell is a single-sided cell, the back metal gate line electrode layer 010 is prepared by screen printing an aluminum paste.

The preparation method of the solar cell provided by the embodiment of the application has at least the following advantages:

the back surface of the solar cell is doped and passivated at the grouting groove by adopting the boron-aluminum paste for back field doping, heavy doping and aluminum-silicon alloy formation are carried out, and the boron-aluminum paste for back field doping is beneficial to improving the open-circuit voltage of the solar cell.

The boron-aluminum slurry for back field doping forms a P + + layer in the back field at the grouting groove under the action of laser, so that the carrier concentration of the back field is increased, the carrier recombination of a laser grooving area is reduced, and the open-circuit voltage of the solar cell is improved. Secondly, the boron-aluminum paste forms aluminum-silicon alloy under the laser doping condition, so that the cavity of the laser doping layer in contact with the back silver electrode lead-out layer is reduced, the contact resistance is reduced, the series resistance of the cell is further reduced, the filling factor of the solar cell is increased, and the efficiency of the solar cell is finally improved.

The preparation of the silicon oxide chemical passivation layer is carried out on two sides, the utilization rate of the tubular annealing furnace equipment is high, the process is simple, the high-efficiency crystalline silicon solar cell is manufactured, the generated energy is increased, and the production and manufacturing are reduced.

The application also provides a solar cell which is mainly prepared by the preparation method. The solar cell provided by the embodiment of the application has better cycle performance.

The features and properties of the present application are described in further detail below with reference to examples.

Example 1

The embodiment provides boron-aluminum paste for back surface field doping and a solar cell.

The boron-aluminum paste for back field doping comprises the following components in percentage by mass:

35% of trimethyl borane, 15% of aluminum chloride, 15% of ethylene (chloromethyl) dimethoxysilane and 35% of organic carrier, wherein the organic carrier comprises 1:1:1 isopropyl carbinol, tetraethyl silicate and glass powder.

The solar cell is prepared by the following preparation method:

(1) a P-type silicon substrate 005 is selected, and cleaning and texturing steps are carried out to form a pyramid shape with a surface textured structure, the resistivity is 0.3 omega cm, and the thickness of the substrate is 150 micrometers.

(2) Preparing an N-type phosphorus source doping layer 004 on the upper surface of a P-type silicon substrate 005 by using phosphorus source diffusion equipment, wherein the boron doping concentration is 10²⁰atoms/cm³The thickness of the boron source doped layer is 300 nm.

(3) Carrying out laser selective doping on the upper surface of the N-type phosphorus source doping layer 004, and then carrying out HNO₃And the solution and the HF solution are subjected to edge etching to eliminate phosphorus sources diffused at the edges, so that the electric leakage of the solar cell is avoided.

(4) And (3) transporting the etched N-type phosphorus source doped layer 004 to a tubular annealing furnace, and introducing dry oxygen, wherein the oxygen flow is 10L/min, the temperature is 800 ℃, the preparation time is 20min, and the thickness is 1 nm. A front silicon oxide chemical passivation layer 003 is formed on the surface of the N-type phosphorus source doping layer 004, and a back silicon oxide chemical passivation layer 007 is formed on the lower surface of the P-type silicon substrate 005;

(5) a front-side silicon nitride anti-reflective layer 002 was formed using PECVD over the front-side silicon oxide chemical passivation layer 003, the silicon source being from SiH₄Gas, SiH₄：NH₃The flow ratio of (2: 1), the thickness of the front-side silicon nitride antireflection layer 002 was 70nm, and the refractive index n was 2.0.

(6) And preparing a nickel oxide field passivation layer 008 on the lower surface of the back silicon oxide chemical passivation layer 007 by using ALD (atomic layer deposition) deposition equipment, wherein a nickel source is nickel acetate, the flow ratio of the nickel acetate to oxygen is 2:1, the reaction temperature is 180 ℃, and the thickness of the nickel oxide field passivation layer 008 is 20 nm.

(7) The backside silicon nitride cap layer 009 is prepared by PECVD on the lower surface of the alumina field passivation layer 008, the silicon source is from SiH₄Gas, SiH₄：NH₃The flow ratio of (3) to (1) was set, and the thickness of the back silicon nitride protective layer 009 was 100 nm.

(8) The back silicon nitride cap layer 009 is laser grooved. Printing boron aluminum paste at the aligned position by screen printing, and then forming a boron aluminum paste doping layer 006 under the action of laser; the laser spot is square, and the spot is 20 multiplied by 20 mu m²And the laser frequency is 80 KHz.

(9) A back metal grid line electrode layer 010 is prepared on the boron-aluminum paste doping layer 006 through screen printing of silver paste, and the back metal grid line electrode layer 010 is used for collecting battery back field carriers.

(10) And (3) screen-printing silver paste on the front silicon nitride antireflection layer 002 to prepare a front current-carrying collection metal grid line electrode layer 001, wherein the thickness of the metal grid line electrode layer 001 is 30 micrometers.

Examples 2 to 6 and comparative examples 1 to 3

Examples 2 to 6 provide a boron aluminum paste for back field doping and a solar cell, respectively. The differences from example 1 are shown in Table 1.

In addition, there is a difference between embodiment 2 and embodiment 1 in that in embodiment 2, the back silicon oxide chemical passivation layer 007, the nickel oxide field passivation layer 008 and the back silicon nitride protective layer 009 are prepared; then preparing a front silicon nitride antireflection layer 002; and then preparing a slurry tank by laser grooving.

Comparative examples 1 to 3 provide a boron aluminum paste for back surface field doping and a solar cell, respectively. The differences from example 1 are shown in Table 1.

TABLE 1

In the table: NiO_xAnd x is greater than 0 and less than or equal to 2.

Fig. 2 shows schematic diagrams of open circuit voltages of the solar cells provided in example 1 and comparative example 1.

Referring to table 1 and fig. 2, the open circuit voltage of the solar cell provided in example 1 is increased by about 4mV compared to the open circuit voltage of the solar cell provided in comparative example 1, and is converted into an increase of the photoelectric efficiency by 0.3% and the fill factor, so that the efficiency of the solar cell can be improved by 0.5%. The open-circuit voltage of the solar cell prepared from the boron-aluminum paste for back field doping provided by the application is higher, and the boron-aluminum paste for back field doping provided by the embodiment of the application is more beneficial to improving the solar cell of which the field passivation layer material is nickel oxide.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.