A high-boron-doped silicon target material and preparation method thereof and solar cell

Abstract

The present application relates to the technical field of target material preparation, and provides a high-boron-doped silicon target material, a preparation method thereof, and a solar cell. The preparation method comprises: mixing silicon-boron compound powder and silicon powder to obtain a mixed powder; thermally spraying the mixed powder, and then mechanically crushing to obtain a silicon-boron alloy block; airflow crushing the silicon-boron alloy block to obtain a silicon-boron alloy powder; thermally spraying the silicon-boron alloy powder onto a back tube, and then machining to obtain a silicon target material. The present application thermally sprays a mixed powder of silicon-boron compound powder and silicon powder, so that the silicon-boron compound powder and the silicon powder are heated to a molten or semi-molten state, so that the silicon-boron compound powder and the silicon powder are firmly combined to form a silicon-boron alloy, so that the silicon-boron compound is not separated after airflow crushing, which helps to improve the boron deposition rate and accurately control the boron content of the silicon target material. As a master alloy with a high boron content, the silicon-boron compound is not affected by the low solid solubility of boron in silicon, and it is easy to prepare a high-boron-doped silicon target material.

Description

Technical Field

[0001] The present application belongs to the technical field of target material preparation, and in particular relates to a high-boron-doped silicon target material, a preparation method thereof, and a solar cell. Background Art

[0002] Crystalline silicon heterojunction solar cells (HJT) have the advantages of high conversion efficiency, good stability, low attenuation rate and double-sided power generation, which makes them have broad market prospects. Its structure includes a first electrode, a first transparent conductive film layer, a p-type silicon layer, a first intrinsic silicon layer, crystalline silicon, a second intrinsic silicon layer, an n-type silicon layer, a second transparent conductive film layer and a second electrode stacked in sequence. The p-type silicon layer is the window material of the HJT cell, and its performance directly affects the conversion efficiency of the HJT cell.

[0003] At present, the methods for preparing p-type silicon layers mainly include CVD (chemical vapor deposition) and PVD. Although the p-type silicon prepared by CVD is of high quality, it requires the use of silicon source and doping gas sources such as B2H6, B(CH3)3 or BF3, which have defects such as high toxicity, environmental pollution caused by reaction tail gas, and high deposition temperature. In contrast, magnetron sputtering in the PVD method uses boron-doped silicon target as raw material, does not require precursors, is green and environmentally friendly, and has mature industrial production and good film quality. It is expected to become the mainstream method for preparing p-type silicon.

[0004] The methods commonly used to prepare boron-doped silicon targets include: mixing silicon powder and boron powder evenly and then plasma spraying; or mixing silicon powder and boron powder and then spraying granulation, and then plasma spraying. However, both methods have a low boron deposition rate, and it is difficult to accurately control the boron content in the silicon target, which affects the performance of the silicon target coating. If, in order to accurately control the boron content, silicon powder and boron powder are melted, crushed and ball-milled at high temperature to form silicon-boron alloy powder before plasma spraying, additional melting equipment is required, which will lead to excessively high manufacturing costs; and even after melting treatment, it is difficult to prepare a high-boron-doped silicon target because the maximum solid solubility of boron in silicon is about 3.5%. Summary of the invention

[0005] The purpose of the present application is to provide a high-boron-doped silicon target material, a preparation method thereof and a solar cell, aiming to solve the problem that the existing preparation method of boron-doped silicon target material has difficulty in accurately controlling the boron content of the silicon target material, or it is difficult to prepare a high-boron-doped silicon target material.

[0006] In order to achieve the above application purpose, the technical solution adopted in this application is as follows:

[0007] In a first aspect, the present application provides a method for preparing a high-boron-doped silicon target, comprising the following steps:

[0008] The silicon-boron compound powder and silicon powder are mixed to obtain a mixed powder;

[0009] The mixed powder is subjected to thermal spraying treatment, and then mechanically crushed to obtain a silicon-boron alloy block;

[0010] Grinding the silicon-boron alloy block by air flow to obtain silicon-boron alloy powder;

[0011] The silicon-boron alloy powder is thermally sprayed onto a backing tube, and then machined to obtain a high-boron-doped silicon target.

[0012] In a second aspect, the present application provides a high-boron-doped silicon target material, including a high-boron-doped silicon target material prepared by the method for preparing the high-boron-doped silicon target material provided in the present application;

[0013] The boron content of the high-boron-doped silicon target material is 1-5wt%.

[0014] In a third aspect, the present application provides a solar cell, comprising a p-type silicon layer, wherein the p-type silicon layer is obtained by sputtering and coating the high-boron-doped silicon target material provided by the present application.

[0015] Compared with the prior art, this application has the following beneficial effects:

[0016] (1) The mixed powder of silicon-boron compound powder and silicon powder is thermally sprayed to heat the silicon-boron compound powder and silicon powder to a molten or semi-molten state, so that the silicon-boron compound powder and silicon powder are firmly combined to form a silicon-boron alloy. As a result, the silicon-boron compound is not separated from the silicon-boron alloy block after air flow crushing, which helps to improve the boron deposition rate and accurately control the boron content of the high-silicon doped silicon target.

[0017] (2) The added silicon-boron compound raw material is used as a master alloy with a high boron content and will not be affected by the low solid solubility of boron in silicon. Therefore, it is easy to prepare a high-boron-doped silicon target.

[0018] (3) The preparation method of the present application successfully achieves uniform alloying of silicon-boron compound powder and silicon powder with large melting point differences through thermal spraying, without the need for additional high-temperature smelting equipment, and has low manufacturing costs. At the same time, it avoids the use of high-temperature smelting that causes component segregation due to large differences in the melting points of the raw materials, which affects the spraying effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1It is a process flow chart of the method for preparing a high-boron-doped silicon target provided in an embodiment of the present application. DETAILED DESCRIPTION

[0021] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0022] The first aspect of the present application provides a method for preparing a high-boron-doped silicon target material, such as Figure 1 As shown, the following steps are included:

[0023] S01: mixing silicon-boron compound powder and silicon powder to obtain mixed powder;

[0024] S02: thermally spraying the mixed powder, and then mechanically crushing it to obtain a silicon-boron alloy block;

[0025] S03: Grinding the silicon-boron alloy block by air flow to obtain silicon-boron alloy powder;

[0026] S04: thermally spray silicon-boron alloy powder onto the backing tube, and then machine it to obtain a high-boron-doped silicon target.

[0027] The preparation method of the silicon target provided by the embodiment of the present application, the high-boron-doped silicon target and its preparation method and solar cell provided by the present application, the mixed powder of silicon-boron compound powder and silicon powder is thermally sprayed, and the silicon-boron compound powder and silicon powder are heated to a molten or semi-molten state, so that the silicon-boron compound powder and silicon powder are firmly combined to form a silicon-boron alloy, so that the silicon-boron compound is not separated after the silicon-boron alloy block is crushed by air flow, which helps to improve the deposition rate of boron and accurately control the boron content of the silicon target; and the added silicon-boron compound raw material is used as a master alloy with a high boron content, which will not be affected by the low solubility of boron in silicon, so it is easy to prepare a high-boron-doped silicon target. In addition, the preparation method of the present application realizes uniform alloying of silicon-boron compound powder and silicon powder with a large melting point difference through thermal spraying, without the need to use additional high-temperature smelting equipment, and the manufacturing cost is low, while avoiding the problem of using high-temperature smelting to affect the spraying effect due to component segregation caused by the large difference in the melting point of the raw materials.

[0028] In the above step S01, in the embodiment, the oxygen content of the silicon-boron compound powder and the silicon powder is less than 500 ppm, and the metal impurity content is less than 100 ppm.

[0029] In an embodiment, the silicon-boron compound powder is selected from silicon hexaboride powder.

[0030] In the embodiment, the mass ratio of silicon hexaboride powder to silicon powder is (1.4-7.2) / (92.8-98.6).

[0031] In an embodiment, the mixing process may be ball milling the silicon hexaboride powder and the silicon powder, mainly to mix the silicon hexaboride powder and the silicon powder uniformly.

[0032] In the embodiment, the particle size of the mixed powder is 75-150 μm.

[0033] In the above step S02, in the embodiment, the step of subjecting the mixed powder to thermal spraying treatment includes: using vacuum plasma spraying equipment, spraying the mixed powder into a collecting device under an argon-hydrogen mixed atmosphere; in the argon-hydrogen mixed atmosphere, the volume ratio of argon to hydrogen is (91~95) / (5~9). Spraying under the conditions of an argon-hydrogen mixed atmosphere can prevent silicon oxidation and ensure the high silicon purity and low oxygen content of the boron-doped silicon target. The mixed powder is heated to a molten or semi-molten state by using vacuum plasma spraying equipment, so that the hexaboride silicon powder and the silicon powder are firmly combined, so that the hexaboride silicon-boron alloy block is not separated after the gas flow crushing, which helps to improve the boron deposition rate and accurately control the boron content of the silicon target; and through the thermal spraying treatment of this embodiment, the hexaboride silicon powder and the silicon powder with a large difference in melting point are uniformly alloyed, avoiding the problem of using high-temperature smelting to cause component segregation due to the large difference in the melting point of the raw materials, which affects the spraying effect.

[0034] Specifically, the collecting device can be a collecting container with a cooling function, and the vacuum plasma spraying equipment sprays the silicon-boron alloy powder into the collecting container for collection, and then knocks it off and mechanically crushes it to obtain a silicon-boron alloy block.

[0035] In the embodiment, the particle size of the silicon-boron alloy block is 0.5-5 mm. The silicon-boron alloy obtained by thermal spraying is mechanically crushed into the particle size range, which is conducive to the air flow crushing of the silicon-boron alloy block.

[0036] In the above step S03, the air flow pulverization is performed in an air flow pulverizer.

[0037] In the embodiment, the particle size of the silicon-boron alloy powder is 75-150 μm. The boron-doped silicon powder in this particle size range has good fluidity, high spraying efficiency and good target quality.

[0038] In the above step S04, in the embodiment, the step of thermally spraying the silicon-boron alloy powder onto the backing tube comprises: spraying the silicon-boron alloy powder onto the backing tube using a vacuum plasma spraying device including a spray gun;

[0039] Among them, the distance from the spray gun to the central axis of the back tube is 95~115mm. If the distance between the spray gun and the central axis of the back tube is too long, the speed of the particles will be reduced, the kinetic energy will be reduced, and the bonding strength between the coatings and the coating and the back tube will be reduced, which will eventually affect the density and strength of the silicon target obtained by spraying; if the distance between the spray gun and the central axis of the back tube is too short, the speed of the particles will be too large, which will easily cause powder splashing and reduce the deposition rate of the sprayed powder. Therefore, within the scope of this embodiment, the silicon-boron alloy powder has a higher deposition rate, and the silicon target has a higher density and stronger mechanical strength; the moving speed of the spray gun is 30~80mm / s. This moving speed range allows the silicon-boron alloy powder to be more evenly sprayed on the back tube. The coating will not be too thick in some areas, which will affect the bonding strength between the coatings and between the coating and the back tube; the rotation speed of the back tube is 200~300r / mim, and this rotation speed range allows the silicon-boron alloy powder to be sprayed on the back tube more evenly, and the coating will not be too thick in some areas, which will affect the bonding strength between the coatings and between the coating and the back tube; the powder feeding amount is 100~200g / min, and this powder feeding amount range can ensure a high spraying efficiency, and is also conducive to the uniform spraying of the silicon-boron alloy powder on the back tube to form a uniform and dense target material; the atmosphere is an argon-hydrogen mixture; wherein, the volume ratio of hydrogen to argon in the argon-hydrogen mixture is (91~95) / (5~9). Spraying under the conditions of argon-hydrogen mixed gas can prevent silicon oxidation and ensure the high silicon purity and low oxygen content of the high-boron-doped silicon target.

[0040] In an embodiment, machining includes: sandblasting and arc priming of the back tube surface respectively, and spraying can make the surface clean and have a certain roughness; wherein, the sand can be selected from white corundum or brown corundum, and the self-fluxing alloy can be selected from copper-aluminum alloy or nickel-aluminum alloy.

[0041] A second aspect of the embodiments of the present application provides a high-boron-doped silicon target material, including a high-boron-doped silicon target material prepared by the method for preparing a high-boron-doped silicon target material provided in the embodiments of the present application;

[0042] The boron content of high boron doped silicon target is 1~5wt%.

[0043] The high boron doped silicon target material provided in the embodiment of the present application is prepared by the preparation method of the high boron doped silicon target material provided in the embodiment of the present application. Therefore, the high boron doped silicon target material provided in the embodiment of the present application has the advantages of low oxygen content, high purity and low resistivity.

[0044] A third aspect of an embodiment of the present application provides a solar cell, comprising a p-type silicon layer, wherein the p-type silicon layer is obtained by sputtering and coating the high-boron-doped silicon target material provided by an embodiment of the present application.

[0045] The solar cell provided in the embodiment of the present application has good conductivity, which helps to improve the conversion efficiency of the solar cell because the p-type silicon layer contained therein is obtained by sputtering and coating the high-boron-doped silicon target material provided in the present application.

[0046] The following describes the invention in conjunction with specific embodiments.

[0047] Example 1

[0048] This embodiment provides a method for preparing a high-boron-doped silicon target, comprising the following steps:

[0049] S11: Silicon hexaboride powder (oxygen content less than 500 ppm, metal impurity content less than 100 ppm) and silicon powder (oxygen content less than 500 ppm, metal impurity content less than 100 ppm) with a mass ratio of 4.30 / 95.70 are ball-milled and mixed to obtain a mixed powder (D50=125 μm);

[0050] S12: using vacuum plasma spraying equipment, in an argon-hydrogen mixed atmosphere (argon: hydrogen volume ratio is 93 / 7), spraying the mixed powder into a collecting device, and mechanically crushing to obtain a silicon-boron alloy block (D50=3 mm);

[0051] S13: loading the silicon-boron alloy block into a jet mill, and jet milling the silicon-boron alloy block under an argon atmosphere to obtain silicon-boron alloy powder (D50=122 μm);

[0052] S14: The processed back tube is installed on the frame, and the frame drives the back tube to rotate and move axially. The spray gun is installed 105mm above the central axis of the back tube. The movement speed of the spray gun is set to 50mm / s, the rotation speed of the back tube is 250r / min, the powder feeding amount is 150g / min, and the powder feeding gas and the working gas are both argon-hydrogen mixed gas (the volume ratio of argon and hydrogen is 93 / 7). During the spraying process, water is passed into the back tube to make the temperature of the back tube surface 80℃, and the silicon-boron alloy powder is sprayed onto the back tube. The spraying is carried out for 2h to obtain a high-boron-doped silicon target.

[0053] Example 2

[0054] This embodiment provides a method for preparing a high-boron-doped silicon target material, which is different from Embodiment 1 in that:

[0055] In step S11, the mass ratio of silicon hexaboride powder to silicon powder is 1.43 / 98.57.

[0056] Example 3

[0057] This embodiment provides a method for preparing a high-boron-doped silicon target material, which is different from Embodiment 1 in that:

[0058] In step S11, the mass ratio of silicon hexaboride powder to silicon powder is 7.15 / 92.85.

[0059] Comparative Example 1

[0060] This comparative example provides a method for preparing a high-boron-doped silicon target, comprising the following steps:

[0061] S1: Silicon hexaboride powder (oxygen content less than 500 ppm, metal impurity content less than 100 ppm) and silicon powder (oxygen content less than 500 ppm, metal impurity content less than 100 ppm) with a mass ratio of 4.30 / 95.70 are ball-milled and mixed to obtain a mixed powder (D50=125 μm);

[0062] S2: The processed back tube is installed on the frame, and the frame drives the back tube to rotate and move axially. The spray gun is installed 105mm above the central axis of the back tube. The movement speed of the spray gun is set to 50mm / s, the rotation speed of the back tube is 250r / min, the powder feeding amount is 150g / min, and the powder feeding gas and the working gas are both argon-hydrogen mixed gas (the volume ratio of argon and hydrogen is 93 / 7). During the spraying process, water is passed into the back tube to make the temperature of the back tube surface 80℃, and the mixed powder is sprayed onto the back tube for 2h to obtain a high-boron-doped silicon target.

[0063] Comparative Example 2

[0064] This comparative example provides a method for preparing a high-boron-doped silicon target, comprising the following steps:

[0065] S1: Silicon hexaboride powder (oxygen content less than 500ppm, metal impurity content less than 100ppm), silicon powder (oxygen content less than 500ppm, metal impurity content less than 100ppm) and ethanol are ball-milled and mixed, and then polyvinyl alcohol is added and mixed evenly to obtain a slurry; wherein the mass ratio of silicon hexaboride powder to silicon powder is 4.30 / 95.70; the amount of polyvinyl alcohol added is 0.5% of the total mass of silicon hexaboride powder and silicon powder, and the solid content of the slurry is 75%;

[0066] S2: introducing the slurry into a centrifugal spray granulator, setting the inlet temperature to 200°C and the outlet temperature to 100°C to obtain granulated powder;

[0067] S3: The processed back tube is installed on the frame, and the frame drives the back tube to rotate and move axially. The spray gun is installed 105mm above the central axis of the back tube. The movement speed of the spray gun is set to 50mm / s, the rotation speed of the back tube is 250r / min, the powder feeding amount is 150g / min, and the powder feeding gas and the working gas are both argon-hydrogen mixture (the volume ratio of argon and hydrogen is 93 / 7). During the spraying process, water is passed into the back tube to make the temperature of the back tube surface 80℃, and the granulated powder is sprayed onto the back tube for 2h to obtain a high-boron-doped silicon target.

[0068] Comparative Example 3

[0069] This comparative example provides a method for preparing a high-boron-doped silicon target, comprising the following steps:

[0070] S1: placing silicon hexaboride powder (oxygen content less than 500ppm, metal impurity content less than 100ppm) and silicon powder (oxygen content less than 500ppm, metal impurity content less than 100ppm) with a mass ratio of 4.30 / 95.70 in a smelting furnace for high-temperature smelting to form silicon-boron ingots;

[0071] S2: Mechanically crushing, ball milling and sieving the silicon boron ingot to obtain silicon boron powder, and then drying the silicon boron powder at 100°C for 30 minutes to obtain silicon boron alloy powder (D50=125μm);

[0072] S3: The processed back tube is installed on the frame, and the frame drives the back tube to rotate and move axially. The spray gun is installed 105mm above the central axis of the back tube. The movement speed of the spray gun is set to 50mm / s, the rotation speed of the back tube is 250r / min, the powder feeding amount is 150g / min, and the powder feeding gas and the working gas are both argon-hydrogen mixed gas (the volume ratio of argon and hydrogen is 93 / 7). During the spraying process, water is passed into the back tube to make the temperature of the back tube surface 80℃, and the silicon-boron alloy powder is sprayed onto the back tube. The spraying is carried out for 2h to obtain a high-boron-doped silicon target.

[0073] Comparative Example 4

[0074] This comparative example provides a method for preparing a high-boron-doped silicon target, comprising the following steps:

[0075] S1: placing boron powder (oxygen content less than 500ppm, metal impurity content less than 100ppm) and silicon powder (oxygen content less than 500ppm, metal impurity content less than 100ppm) with a mass ratio of 3.0 / 97.0 in a smelting furnace for high-temperature smelting to form silicon-boron ingots;

[0076] S2: Mechanically crushing, ball milling and sieving the silicon boron ingot to obtain silicon boron powder, and then drying the silicon boron powder at 100°C for 30 minutes to obtain silicon boron alloy powder (D50=124μm);

[0077] S3: The processed back tube is installed on the frame, and the frame drives the back tube to rotate and move axially. The spray gun is installed 105mm above the central axis of the back tube. The movement speed of the spray gun is set to 50mm / s, the rotation speed of the back tube is 250r / min, the powder feeding amount is 150g / min, and the powder feeding gas and the working gas are both argon-hydrogen mixed gas (the volume ratio of argon and hydrogen is 93 / 7). During the spraying process, water is passed into the back tube to make the temperature of the back tube surface 80℃, and the silicon-boron alloy powder is sprayed onto the back tube. The spraying is carried out for 2h to obtain a high-boron-doped silicon target.

[0078] Related performance test analysis:

[0079] 1. The resistivity of the high-boron-doped silicon targets prepared in Examples 1 to 3 and Comparative Examples 1 to 4 was tested using a four-probe tester;

[0080] 2. The boron content of the high-boron-doped silicon targets prepared in Examples 1 to 3 and Comparative Examples 1 to 4 was tested using an ICP spectrometer;

[0081] The test results are shown in Table 1 below:

[0082] Table 1

[0083]

[0084] As can be seen from Table 1, the boron content of the high-boron-doped silicon target prepared in Examples 1 to 3 is substantially the same as the boron content of the raw material powder (silicon hexaboride powder + silicon powder), while the boron content of the high-boron-doped silicon target prepared in Comparative Examples 1 and 2 is significantly lower than the boron content of the raw material powder (silicon hexaboride powder + silicon powder), indicating that in the embodiments of the present application, a mixed powder of silicon hexaboride powder and silicon powder is thermally sprayed to form a silicon-boron alloy, so that the silicon-boron alloy block is not separated from the silicon hexaboride after airflow crushing, so that the silicon hexaboride powder and the silicon powder can be deposited together with the same deposition rate, and thus the boron content of the high-boron-doped silicon target can be accurately controlled, overcoming the problem of low deposition rate of boron in silicon powder using boron powder as raw material in the traditional method.

[0085] The boron content of the boron-doped silicon target prepared in Comparative Example 3 is lower than the boron content of the raw powder (silicon hexaboride powder + silicon powder). This is mainly because the melting points of silicon hexaboride powder (melting point 2200°C) and silicon powder (1414°C) are very different, and boron segregation is likely to occur during the cooling process of smelting, resulting in part of the boron failing to penetrate into the silicon matrix to form a silicon-boron alloy, and being separated during the subsequent mechanical crushing and ball milling process, thereby affecting the boron deposition rate, causing the boron content of the silicon target to deviate from the boron content of the raw powder.

[0086] The boron content of the boron-doped silicon target prepared in Comparative Example 4 is lower than the boron content of the raw material powder (boron powder + silicon powder). This is mainly because the solid solubility of boron in silicon is relatively small, and it may be impossible for all the boron powder to be dissolved in the silicon powder. It is also possible that all the boron is dissolved in the silicon powder during high-temperature smelting but segregation occurs during the cooling process. Therefore, it is impossible for all the boron powder and silicon powder to be dissolved to form an alloy, resulting in separation during the subsequent mechanical crushing and ball milling processes, thereby affecting the boron deposition rate, causing the boron content of the silicon target to deviate from the boron content of the raw material powder.

[0087] The resistivity of the high-boron-doped silicon target prepared in Examples 1 to 3 is lower than that in Comparative Examples 1 to 4, indicating that the preparation method of the embodiments of the present application can prepare a high-boron-doped silicon target with good conductivity and low manufacturing cost.

[0088] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a high-boron-doped silicon target, characterized in that: The following steps are involved: The silicon boron compound powder and silicon powder are mixed to obtain a mixed powder; the silicon boron compound powder is selected from silicon hexaboride powder; the mass ratio of the silicon hexaboride powder to the silicon powder is (1.4-7.2) / (92.8-98.6); The mixed powder is subjected to thermal spraying treatment, and then mechanically crushed to obtain a silicon-boron alloy block; wherein the step of thermal spraying the mixed powder comprises: using vacuum plasma spraying equipment, in an argon-hydrogen mixed atmosphere, spraying the mixed powder into a collecting device; in the argon-hydrogen mixed atmosphere, the volume ratio of argon to hydrogen is (91-95) / (5-9); Grinding the silicon-boron alloy block by air flow to obtain silicon-boron alloy powder; The silicon-boron alloy powder is thermally sprayed onto a backing tube, and then machined to obtain a high-boron-doped silicon target.

2. The preparation method according to claim 1, characterized in that The particle size of the mixed powder is 75-150 μm.

3. The preparation method according to claim 1, characterized in that: The particle size of the silicon-boron alloy block is 0.5-5 mm.

4. The preparation method according to claim 1, characterized in that: The particle size of the silicon-boron alloy powder is 75-150 μm.

5. The preparation method according to any one of claims 1 to 4, characterized in that The step of thermally spraying the silicon-boron alloy powder onto the backing tube comprises: spraying the silicon-boron alloy powder onto the backing tube using a vacuum plasma spraying device including a spray gun; Among them, the distance from the spray gun to the central axis of the back tube is 95~115mm, the moving speed of the spray gun is 30~80mm / s, the rotation speed of the back tube is 200~300r / mim, the powder feeding amount is 100~200g / min, and the atmosphere is an argon-hydrogen mixture.

6. The preparation method according to claim 5, characterized in that: In the argon-hydrogen mixed gas, the volume ratio of argon to hydrogen is (91-95) / (5-9).

7. A high-boron-doped silicon target, characterized in that: A high-boron-doped silicon target prepared by the method for preparing a high-boron-doped silicon target according to any one of claims 1 to 6; The boron content of the high-boron-doped silicon target material is 1-5wt%.

8. A solar cell comprising a p-type silicon layer, characterized in that: The p-type silicon layer is obtained by sputtering and coating the high-boron-doped silicon target material according to claim 7.

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