Preparation method of solar cell and solar cell

Abstract

The invention provides a preparation method of a solar cell and the solar cell, and relates to the technical field of photovoltaics. The method comprises the steps that a P-type silicon wafer is provided, a tunneling oxide layer and a polycrystalline silicon layer are sequentially formed on one side of the P-type silicon wafer in a stacked mode, phosphorus diffusion doping is conducted on the polycrystalline silicon layer to form a phosphorus-doped polycrystalline silicon layer, and a phosphorosilicate glass layer is generated; the surface of the phosphorosilicate glass layer is locally coated with an acidic etching coating, and the acidic etching coating etches off the local phosphorosilicate glass layer below the acidic etching coating, so that the phosphorus-doped polycrystalline silicon layer is partially exposed; carrying out wet etching by taking the residual phosphorosilicate glass layer as a mask so as to remove the exposed phosphorus-doped polycrystalline silicon layer and the tunneling oxide layer below the phosphorus-doped polycrystalline silicon layer; a solution used by the wet etching is an alkaline solution. The time for coating the acidic etching coating is short, and the productivity can be improved; the acidic etching coating is easy to clean, does not damage the silicon wafer, and is low in cost. And performing wet etching to form a P region, and forming an N region by taking the residual phosphorosilicate glass layer as a mask.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a method for preparing a solar cell and a solar cell. Background Art

[0002] As a renewable resource, solar energy has the advantages of high efficiency and no pollution. With the development of photovoltaic technology, solar cells have been widely used. IBC solar cell is the abbreviation of interdigitated back contact silicon solar cell. The characteristics of IBC solar cell are that there is no grid electrode on the surface facing the light, and the positive and negative electrodes are arranged crosswise on the backlight side. This structure makes the IBC solar cell "zero shielding" on the light side, thereby increasing the absorption and utilization of light and achieving a significant improvement in conversion efficiency. At present, laser ablation technology is usually used to prepare the P and N regions of solar cells. Laser ablation refers to the use of a laser beam with a higher energy density to irradiate the surface of the processed material. The surface of the material absorbs the laser energy, the temperature rises, and melting, ablation, and evaporation occur, thereby achieving the purpose of removing the surface layer.

[0003] However, the use of laser ablation technology to prepare the P and N regions of solar cells will damage the silicon wafer due to the high laser energy, reducing the life and performance of the solar cell. Secondly, since the patterns of the P and N regions of the solar cell are relatively complex, the laser film opening time is long, and the power of the laser is attenuated, resulting in a long preparation time and low production capacity for the P and N regions of the solar cell. In addition, the cost of the laser is high, and the cost of replacing and maintaining the laser is high. Summary of the invention

[0004] The present invention provides a method for preparing a solar cell and a solar cell, aiming to solve the problems in the prior art of using laser ablation technology to prepare the P region and N region of the solar cell, which may damage the silicon wafer and reduce the life and performance of the solar cell, and the long preparation time, low production capacity and high cost of preparing the P region and N region of the solar cell.

[0005] A first aspect of the present invention provides a method for preparing a solar cell, comprising:

[0006] Providing a P-type silicon wafer, sequentially stacking a tunneling oxide layer and a polysilicon layer on one side of the P-type silicon wafer, performing phosphorus diffusion doping on the polysilicon layer to form a phosphorus-doped polysilicon layer, and generating a phosphorus-silicate glass layer on a side of the phosphorus-doped polysilicon layer away from the P-type silicon wafer;

[0007] Partially coating the surface of the phosphorus-silicate glass layer with an acidic etching coating, wherein the acidic etching coating etches away a part of the phosphorus-silicate glass layer thereunder, so that the phosphorus-doped polysilicon layer is partially exposed;

[0008] Using the remaining phosphosilicate glass layer as a mask, wet etching is performed to remove the exposed phosphorus-doped polysilicon layer and the tunneling oxide layer under the exposed phosphorus-doped polysilicon layer, so that the P-type silicon wafer is partially exposed; the solution used for the wet etching is an alkaline solution.

[0009] In the present invention, the partial phosphorus-silicate glass layer below is etched away by coating an acidic etching coating, and the coating speed is fast, which can improve the production capacity, and the acidic etching coating is easy to clean and will not cause damage to the P-type silicon wafer. In addition, the cost of the acidic etching coating is low, and the coating of the acidic etching coating does not require complex equipment, which is convenient to operate and the maintenance technology is relatively mature. Wet etching is performed to remove the exposed phosphorus-doped polysilicon layer and the tunneling oxide layer below the exposed phosphorus-doped polysilicon layer, so that the P-type silicon wafer is partially exposed to form a P region, and the remaining phosphorus-silicate glass layer is used as a mask to protect the remaining phosphorus-doped polysilicon layer and the tunneling oxide layer below the phosphorus-silicate glass layer to form an N region, thereby forming a partition. In addition, wet etching can clean the acidic etching coating to avoid the residual acidic etching coating from affecting the performance of the solar cell. In addition, the cost of the alkaline solution used for wet etching is low, and at the same time, the alkaline solution used for wet etching is easy to clean and will not cause damage to the P-type silicon wafer. In addition, when laser ablation technology is used to prepare the P region and the N region, wet etching is also required to remove the tunneling oxide layer and the phosphorus-doped polysilicon layer remaining after laser ablation. Wet etching will not increase the time for preparing the P region and the N region.

[0010] Optionally, after locally coating the surface of the phosphosilicate glass layer with an acidic etching coating, the method further comprises:

[0011] The acid etching coating is dried at a temperature of 180 degrees Celsius to 220 degrees Celsius.

[0012] Optionally, after locally coating the surface of the phosphosilicate glass layer with an acidic etching coating and before performing the wet etching, the method further comprises:

[0013] The interval time between locally coating the acid etching coating on the surface of the phosphorus silicon glass layer and performing the wet etching is controlled, and the interval time is 10 minutes to 30 minutes.

[0014] Optionally, the alkaline solution is a potassium hydroxide solution or a sodium hydroxide solution.

[0015] Optionally, the acidic etching coating contains hydrofluoric acid.

[0016] Optionally, after the wet etching, the method further comprises:

[0017] Acid washing is performed to remove the remaining phosphosilicate glass layer.

[0018] Optionally, after the pickling is performed to remove the remaining phosphosilicate glass layer, the method further comprises:

[0019] A passivation layer is formed on both sides of the P-type silicon wafer.

[0020] Optionally, the sequentially stacking a tunnel oxide layer and a polysilicon layer on one side of the P-type silicon wafer includes:

[0021] A tunneling oxide layer and a polysilicon layer are sequentially stacked on one side of the P-type silicon wafer by using a low-pressure chemical vapor deposition method.

[0022] A second aspect of the present invention provides a solar cell, which is prepared by the method for preparing a solar cell as described in the first aspect.

[0023] Optionally, the solar cell comprises a back electrode contact silicon solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0025] Figure 1 A flowchart showing a method for preparing a solar cell according to an embodiment of the present invention is shown;

[0026] Figure 2 A schematic diagram of the structure of a P-type back electrode contact silicon solar cell in the prior art is shown;

[0027] Figure 3 A flowchart showing the steps of another method for preparing a solar cell in an embodiment of the present invention is shown;

[0028] Figure 4 A schematic diagram showing the preparation state of a solar cell in an embodiment of the present invention (providing a P-type silicon wafer);

[0029] Figure 5 A schematic diagram of the preparation state of a solar cell in an embodiment of the present invention is shown (phosphorus diffusion doping is performed);

[0030] Figure 6 A schematic diagram of the preparation state of a solar cell in an embodiment of the present invention is shown (coating with an acidic etching coating);

[0031] Figure 7 A schematic diagram of the preparation state of a solar cell in an embodiment of the present invention is shown (the phosphorus silicon glass layer is partially etched away below the acid etching coating);

[0032] Figure 8 A schematic diagram of the preparation state of a solar cell in an embodiment of the present invention is shown (the phosphorus silicon glass layer on the light-facing surface is removed);

[0033] Fig. 9 A schematic diagram showing the preparation state of a solar cell in an embodiment of the present invention (wet etching + texturing);

[0034] Fig.10 A schematic diagram showing the preparation state of a solar cell in an embodiment of the present invention (wet cleaning) is shown.

[0035] Description of reference numerals:

[0036] 10-P-type silicon wafer, 11-tunneling oxide layer, 12-phosphorus-doped polysilicon layer, 13-phosphosilicate glass layer, 14-acid etching coating, 15-aluminum oxide layer, 16-silicon nitride layer, 17-silver electrode, 18-aluminum electrode. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] The present invention provides a method for preparing a solar cell. Figure 1 , Figure 1 A flowchart of a method for preparing a solar cell in an embodiment of the present invention is shown, and the method comprises:

[0039] Step 101, providing a P-type silicon wafer 10, sequentially stacking a tunneling oxide layer 11 and a polysilicon layer on one side of the P-type silicon wafer 10, diffusing phosphorus into the polysilicon layer to form a phosphorus-doped polysilicon layer 12, and generating a phosphorus-silicate glass layer 13 on a side of the phosphorus-doped polysilicon layer 12 away from the P-type silicon wafer 10.

[0040] Since the P-type silicon wafer 10 is obtained by doping silicon with boron, the segregation coefficients of boron and silicon are comparable, and the dispersion uniformity is easy to control, so that the quality of the P-type silicon wafer 10 is higher, and the quality of the solar cell made with the P-type silicon wafer 10 as the substrate is better than that of the solar cell made with the N-type silicon wafer as the substrate. Optionally, before the tunneling oxide layer 11 and the polysilicon layer are sequentially stacked on one side of the P-type silicon wafer 10, a polishing device can be used to polish the P-type silicon wafer 10 to obtain a polished P-type silicon wafer 10. One side of the P-type silicon wafer 10 can be the light-facing side of the P-type silicon wafer 10, and / or, the backlight side. The thickness of the tunneling oxide layer 11 can be 1nm (nanometer) to 2nm, and the tunneling oxide layer 11 is used to facilitate the migration of carriers through the tunneling effect.

[0041] Step 102 , locally coating an acid etching coating 14 on the surface of the phosphosilicate glass layer 13 , wherein the acid etching coating 14 etches away a portion of the phosphosilicate glass layer 13 thereunder, so that the phosphorus-doped polysilicon layer 12 is partially exposed.

[0042] The acid etching coating 14 and the phosphorus silicon glass layer 13 can react. By applying the acid etching coating 14, the local phosphorus silicon glass layer 13 below it is etched away. The coating speed is fast, which can improve the production capacity, and the acid etching coating 14 is easy to clean and will not damage the P-type silicon wafer 10. In addition, the cost of the acid etching coating 14 is low, and the coating of the acid etching coating 14 does not require complex equipment, which is convenient to operate and the maintenance technology is relatively mature. The coating of the acid etching coating 14 can be assisted by a screen plate, and the cost of the screen plate is also low. In addition, the acid etching coating 14 can also be printed on the local surface of the phosphorus silicon glass layer 13 by printing the acid etching coating 14. The coating pattern or printed pattern can be designed according to the screen pattern. In the embodiment of the present invention, the acid etching coating contains the general components of the coating and the acid, and the corrosion performance of the acid etching coating is adjusted by adjusting the proportion of the acid, and the specific components of the acid etching coating are not limited.

[0043] Step 103, using the remaining phosphosilicate glass layer 13 as a mask, wet etching is performed to remove the exposed phosphorus-doped polysilicon layer 12 and the tunneling oxide layer 11 under the exposed phosphorus-doped polysilicon layer 12, so that the P-type silicon wafer 10 is partially exposed; the solution used for the wet etching is an alkaline solution.

[0044] Wet etching is performed to remove the exposed phosphorus-doped polysilicon layer 12 and the tunneling oxide layer 11 under the exposed phosphorus-doped polysilicon layer 12, so that the P-type silicon wafer 10 is partially exposed to form a P region, and the remaining phosphorus-doped glass layer 13 is used as a mask to protect the phosphorus-doped polysilicon layer 12 and the tunneling oxide layer 11 under the remaining phosphorus-doped glass layer 13 to form an N region, thereby forming a partition. In addition, wet etching can clean the acid etching coating 14 to prevent the residual acid etching coating 14 from affecting the performance of the solar cell. In addition, the cost of the alkaline solution used for wet etching is low, and the alkaline solution used for wet etching is easy to clean and will not damage the P-type silicon wafer 10. In addition, when laser ablation technology is used to prepare the P region and the N region, wet etching is also required to remove the tunneling oxide layer 11 and the phosphorus-doped polysilicon layer 12 remaining after laser ablation. Wet etching will not increase the time for preparing the P region and the N region.

[0045] The inventors found that in the prior art, laser ablation technology is used to prepare the P and N regions of solar cells. Due to the high laser energy, the silicon wafer will be damaged, reducing the life and performance of the solar cell. Secondly, due to the complex patterns of the P and N regions of the solar cell, the laser film opening time is long, and the power of the laser is attenuated, resulting in a long preparation time and low production capacity for the P and N regions of the solar cell. In addition, the cost of the laser is high, and the cost of replacing and maintaining the laser is high. If there is a problem with the laser, the line needs to be stopped for processing, and the cost of the maintenance process is also high.

[0046] In view of the above technical problems, in the embodiment of the present invention, the inventor etches away the local phosphorus silicon glass layer 13 below by coating an acid etching coating 14. The coating speed is fast, which can improve the production capacity. The acid etching coating 14 is easy to clean and will not damage the P-type silicon wafer 10. In addition, the cost of the acid etching coating 14 is low, and the coating of the acid etching coating 14 does not require complex equipment, which is convenient to operate and the maintenance technology is relatively mature. Wet etching is performed to remove the exposed phosphorus-doped polysilicon layer 12 and the tunneling oxide layer 11 below the exposed phosphorus-doped polysilicon layer 12, so that the P-type silicon wafer 10 is partially exposed to form a P region, and the remaining phosphorus silicon glass layer 13 is used as a mask to protect the remaining phosphorus-doped polysilicon layer 12 and the tunneling oxide layer 11 below the phosphorus silicon glass layer 13 to form an N region, thereby forming a partition. And wet etching can clean the acidic etching coating 14, avoiding the residual acidic etching coating 14 from affecting the performance of the solar cell. In addition, the cost of the alkaline solution used for wet etching is low. At the same time, the alkaline solution used for wet etching is easy to clean and will not damage the P-type silicon wafer 10. In addition, when laser ablation technology is used to prepare the P region and the N region, wet etching is also required to remove the tunneling oxide layer 11 and the phosphorus-doped polysilicon layer 12 remaining after laser ablation. Wet etching does not increase the time for preparing the P region and the N region.

[0047] Optionally, after the acid etching coating 14 is partially coated on the surface of the phosphosilicate glass layer 13, the method further comprises: drying the acid etching coating 14, wherein the temperature for drying the acid etching coating 14 is 180 degrees Celsius to 220 degrees Celsius.

[0048] For example, the temperature for drying the acid etching coating 14 can be 180° C., 190° C., 200° C., 210° C., 215° C., or 220° C. The temperature for drying the acid etching coating 14 is 180° C. to 220° C., which can ensure that the acid etching coating 14 solidifies, so that the acid etching coating 14 does not flow randomly and affect the patterns of the P region and the N region, and does not make the acid etching coating 14 dry, so as to avoid affecting the subsequent wet etching of the acid etching coating 14.

[0049] Optionally, after locally coating the surface of the phosphosilicate glass layer 13 with the acidic etching coating 14 and before performing wet etching, the method further includes: controlling the interval time between locally coating the surface of the phosphosilicate glass layer 13 with the acidic etching coating 14 and performing wet etching, the interval time being 10 minutes to 30 minutes.

[0050] For example, the interval time can be 10 minutes, or 15 minutes, or 20 minutes, or 25 minutes, or 28 minutes, or 30 minutes. The interval time is 10 minutes to 30 minutes, which can avoid the interval time being too long, the acid etching coating 14 is completely dry, and the difficulty of wet etching to clean the acid etching coating 14 is increased. At the same time, it is avoided that the time is too short, the acid etching coating 14 and the phosphorus silicon glass layer 13 are not completely reacted, and the local phosphorus silicon glass layer 13 below the acid etching coating 14 cannot be completely removed. In addition, the solar cell production workshop usually adopts assembly line production to batch produce solar cells. For example, after a batch of semi-finished solar cells partially coat the surface of the phosphorus silicon glass layer 13 with the acid etching coating 14, an interval time is waited. At this time, the semi-finished solar cells of the previous batch or the previous batch are waiting to be completed and can enter the next process. The interval time will not affect the production capacity of solar cells. Alternatively, after a batch of semi-finished solar cells partially coat the surface of the phosphorus silicon glass layer 13 with the acid etching coating 14, during the flow of the assembly line to the next process, the flow time can reach the interval time and directly enter the next process. In the embodiment of the present invention, the acid etching coating 14 is dried during the interval time, that is, the time for drying the acid etching coating 14 is less than or equal to 30 minutes, so as to avoid the acid etching coating 14 from drying out and affecting the subsequent wet etching of the acid etching coating 14.

[0051] Optionally, the alkaline solution is a potassium hydroxide solution or a sodium hydroxide solution. The potassium hydroxide solution and the sodium hydroxide solution are highly alkaline and can quickly remove the phosphorus-doped polysilicon layer 12 and the tunneling oxide layer 11 below the phosphorus-doped polysilicon layer 12 .

[0052] Optionally, the acidic etching coating 14 contains hydrofluoric acid. The acidic etching coating 14 contains hydrofluoric acid, and hydrofluoric acid has a better effect of removing the phosphosilicate glass layer 13, so the acidic etching coating 14 has a better effect of removing the phosphosilicate glass layer 13. The corrosion performance of the acidic etching coating can be adjusted by adjusting the proportion of hydrofluoric acid.

[0053] Optionally, after wet etching, the method further includes: performing pickling to remove the remaining phosphosilicate glass layer 13. Removing the remaining phosphosilicate glass layer 13 can prevent the presence of the phosphosilicate glass layer 13 from affecting the contact between the metal electrode and the silicon wafer during the electrode printing process, thereby reducing the photoelectric conversion efficiency of the solar cell. At the same time, it can prevent the metal ion impurities in the phosphosilicate glass layer 13 from reducing the minority carrier lifetime. In addition, pickling can also remove the alkaline solution remaining on the surface of the P-type silicon wafer 10 after wet etching. Acid pickling can be performed using a hydrofluoric acid solution and / or a hydrogen chloride solution. After pickling, water washing can be performed to remove the pickling solution remaining on the surface of the P-type silicon wafer 10 after pickling.

[0054] Optionally, after pickling to remove the remaining phosphorus silicon glass layer 13, the method further includes: forming a passivation layer on both sides of the P-type silicon wafer 10. Passivation layers are formed on both sides of the P-type silicon wafer 10 to passivate the surface of the silicon wafer, which can reduce carrier recombination and improve the photoelectric conversion efficiency of the solar cell. The passivation layer can be an aluminum oxide layer and / or a silicon nitride layer.

[0055] Optionally, sequentially stacking a tunnel oxide layer 11 and a polysilicon layer on one side of the P-type silicon wafer 10 includes: using a low-pressure chemical vapor deposition method to sequentially stack a tunnel oxide layer 11 and a polysilicon layer on one side of the P-type silicon wafer 10. The use of a low-pressure chemical vapor deposition (LPCVD) method can improve the uniformity of the tunnel oxide layer 11 and the polysilicon layer. In addition, the technology of the low-pressure chemical vapor deposition method is relatively mature, and the process temperature for preparing the tunnel oxide layer 11 and the polysilicon layer is similar, both at about 600°C. In the middle of the preparation steps of the tunnel oxide layer 11 and the polysilicon layer, nitrogen cleaning, leak detection, vacuuming and other operations can be added, so that the preparation of the tunnel oxide layer 11 and the polysilicon layer can be completed in the same step.

[0056] The embodiment of the present invention also provides a solar cell, which is prepared by the above-mentioned method for preparing a solar cell. The method for preparing a solar cell according to the embodiment of the present invention is to etch away the local phosphorus-silicate glass layer 13 below it by coating an acidic etching coating 14, and wet etching is performed to remove the exposed phosphorus-doped polysilicon layer 12 and the tunneling oxide layer 11 below the exposed phosphorus-doped polysilicon layer 12, so that the P-type silicon wafer 10 is partially exposed to form a P region, and the remaining phosphorus-silicate glass layer 13 is used as a mask to protect the phosphorus-doped polysilicon layer 12 and the tunneling oxide layer 11 below the remaining phosphorus-silicate glass layer 13 to form an N region, thereby forming a partition, which can increase production capacity, reduce production costs, reduce damage to silicon wafers, and improve the electrical performance of solar cells.

[0057] Optionally, the solar cell includes a back electrode contact silicon solar cell. The characteristic of the IBC solar cell is that there is no grid electrode on the surface facing the light, and the positive and negative electrodes are arranged crosswise on the backlight side. This structure makes the IBC solar cell "zero shading" on the light side, thereby increasing the absorption and utilization of light and achieving a significant improvement in conversion efficiency. Figure 2 , Figure 2The schematic diagram of the structure of a P-type back electrode contact silicon solar cell in the prior art is shown, and the P-type IBC solar cell comprises: a P-type silicon wafer 10, a tunneling oxide layer 11, a phosphorus-doped polycrystalline silicon layer 12, an aluminum oxide layer 15, and a silicon nitride layer 16; the backlight side of the P-type silicon wafer 10 comprises: a P region and an N region; the tunneling oxide layer 11, the phosphorus-doped polycrystalline silicon layer 12, the aluminum oxide layer 15, and the silicon nitride layer 16 are sequentially stacked on the N region on the backlight side of the P-type silicon wafer 10; the aluminum oxide layer 15 and the silicon nitride layer 16 are sequentially stacked on the P region on the backlight side of the P-type silicon wafer 10; the aluminum oxide layer 15 and the silicon nitride layer 16 are sequentially stacked on the light-facing side of the P-type silicon wafer 10; the P region on the backlight side of the P-type silicon wafer 10 is a velvet structure; the light-facing side of the P-type silicon wafer 10 is a velvet structure, and a silver electrode 17 and an aluminum electrode 18 are provided on the backlight side of the P-type IBC solar cell. The method for preparing a solar cell according to the embodiment of the present invention can improve production capacity, reduce production costs, and reduce damage to the IBC solar cell. In the embodiment of the present invention, the type of solar cell can also be a solar cell that needs to form a P region and an N region other than an IBC solar cell, and there is no restriction on the type of solar cell.

[0058] The present invention will be further explained below in conjunction with specific embodiments. Figure 3 , Figure 3 A flowchart of another method for preparing a solar cell in an embodiment of the present invention is shown, which specifically includes the following steps:

[0059] (1) Provide a P-type silicon wafer 10, refer to Figure 4 , Figure 4 A schematic diagram of the preparation state of a solar cell in an embodiment of the present invention is shown (a P-type silicon wafer 10 is provided);

[0060] (2) Double-sided wet polishing;

[0061] (3) using a low pressure chemical vapor deposition method to sequentially stack a tunnel oxide layer 11 and a polysilicon layer on both sides of the P-type silicon wafer 10;

[0062] (4) Phosphorus diffusion doping is performed on the polysilicon layers on both sides of the P-type silicon wafer 10 to form a phosphorus-doped polysilicon layer 12, and a phosphorus-silicate glass layer 13 is formed on the side of the phosphorus-doped polysilicon layer 12 away from the P-type silicon wafer 10, referring to Figure 5 , Figure 5 A schematic diagram of the preparation state of a solar cell in an embodiment of the present invention is shown (phosphorus diffusion doping is performed);

[0063] (5) Acidic etching coating 14 is partially coated on the surface of the phosphorus silicon glass layer 13 on the backlight side of the P-type silicon wafer 10, referring to Figure 6 , Figure 6FIG. 1 shows a schematic diagram of the preparation state of a solar cell in an embodiment of the present invention (coating an acidic etching coating 14). The acidic etching coating 14 etches away a local phosphorus silicon glass layer 13 below it, so that the phosphorus-doped polysilicon layer 12 on the backlight side of the P-type silicon wafer 10 is partially exposed. Figure 7 , Figure 7 A schematic diagram of the preparation state of a solar cell in an embodiment of the present invention is shown (a local phosphorus silicon glass layer 13 below the acid etching coating 14 is etched away);

[0064] (6) Wet single-sided film removal on the light-facing surface: Use hydrofluoric acid solution to remove the phosphorus-silicon glass layer 13 on the light-facing surface. Figure 8 , Figure 8 A schematic diagram of the preparation state of a solar cell in an embodiment of the present invention is shown (the phosphorus silicon glass layer 13 on the light-facing surface is removed);

[0065] (7) Wet etching + texturing: Wet etching is performed to remove the exposed phosphorus-doped polysilicon layer 12 on the backlight side of the P-type silicon wafer 10, and the tunneling oxide layer 11 under the exposed phosphorus-doped polysilicon layer 12, so that the backlight side of the P-type silicon wafer 10 is partially exposed to form a P region, and the backlight side of the P-type silicon wafer 10 covered with the phosphorus-silicate glass layer 13 is the N region, and the phosphorus-doped polysilicon layer 12 and the tunneling oxide layer 11 on the light-facing side of the P-type silicon wafer 10 are removed at the same time; the solution used for wet etching is sodium hydroxide solution; texturing is performed to form a velvet surface on the partially exposed area on the backlight side of the P-type silicon wafer 10, and at the same time, a velvet surface is formed on the light-facing side of the P-type silicon wafer 10, refer to Fig. 9 , Fig. 9 A schematic diagram showing the preparation state of a solar cell in an embodiment of the present invention (wet etching + texturing);

[0066] (8) Wet cleaning: using hydrofluoric acid solution to perform pickling to remove the remaining phosphosilicate glass layer 13 on the backlight side of the P-type silicon wafer 10; performing water washing to remove the hydrofluoric acid solution remaining on the surface of the P-type silicon wafer 10 after pickling; referring to Fig.10 , Fig.10 A schematic diagram showing the preparation state of a solar cell in an embodiment of the present invention (wet cleaning);

[0067] (9) double-sided ALD (Atomic Layer Deposition) aluminum oxide layer 15;

[0068] (10) Plating a silicon nitride layer 16 on the light side and a silicon nitride layer 16 on the back side by PECVD (Plasma Enhanced Chemical Vapor Deposition);

[0069] (11) preparing electrodes, printing silver paste in the N region and aluminum paste in the P region;

[0070] (12) Test the performance of the prepared P-type IBC solar cell.

[0071] Laser ablation technology is used to prepare the P region and N region of the P-type IBC solar cell. Compared with the steps in the method for preparing another solar cell in the above-mentioned embodiment of the present invention, the method for preparing the P-type IBC solar cell using laser ablation technology is different in step (5). Step (5) specifically includes: laser grooving according to a specific laser pattern to remove the local phosphorus silicon glass layer 13 on the backlight side of the P-type silicon wafer 10, so that the phosphorus-doped polysilicon layer 12 on the backlight side of the P-type silicon wafer 10 is partially exposed; the other steps are the same as the steps in the method for preparing another solar cell in the above-mentioned embodiment of the present invention.

[0072] The preparation method of the P-type IBC solar cell using laser ablation technology cannot guarantee that the phosphorus-doped polysilicon layer 12 and the tunneling oxide layer 11 under the local phosphorus-silicate glass layer 13 on the backlight side of the P-type silicon wafer 10 can be completely removed by laser ablation technology. It is also necessary to use alkaline solution wet etching to remove the phosphorus-doped polysilicon layer 12 and the tunneling oxide layer 11, so that the backlight side of the P-type silicon wafer 10 is partially exposed to form a P region.

[0073] The time taken to prepare the P region and the N region by using another method for preparing a solar cell in the above-mentioned embodiment of the present invention and the method for preparing a P-type IBC solar cell using laser ablation technology are compared. When the laser ablation technology is used to prepare the P region and the N region of the P-type IBC solar cell, it takes 60 seconds to open the P region pattern. When using another method for preparing a solar cell in the above-mentioned embodiment of the present invention to prepare the P region and the N region of the P-type IBC solar cell, it only takes about 20 seconds to coat the acid etching coating 14. The two preparation methods differ by about 40 seconds. It can be seen that the method for preparing a solar cell in the embodiment of the present invention can greatly shorten the time for preparing the P region and the N region of the solar cell, thereby increasing the production capacity of the solar cell.

[0074] It should be noted that the relevant parts of the aforementioned method for preparing a solar cell and the solar cell can be referred to each other and can achieve the same or similar effects.

[0075] It should be noted that, for the method embodiments, for the sake of simplicity of description, they are all expressed as a series of action combinations, but those skilled in the art should be aware that the embodiments of the present application are not limited by the described order of actions, because according to the embodiments of the present application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily required by the embodiments of the present application.

[0076] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0077] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, a magnetic disk, or an optical disk), and includes a number of instructions for enabling a terminal (which can be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) to execute the methods described in each embodiment of the present invention.

[0078] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A method for preparing a solar cell, characterized in that: include: Providing a P-type silicon wafer, sequentially stacking a tunneling oxide layer and a polysilicon layer on one side of the P-type silicon wafer, performing phosphorus diffusion doping on the polysilicon layer to form a phosphorus-doped polysilicon layer, and generating a phosphorus-silicate glass layer on a side of the phosphorus-doped polysilicon layer away from the P-type silicon wafer; Partially coating the surface of the phosphorus-silicate glass layer with an acidic etching coating, wherein the acidic etching coating etches away a part of the phosphorus-silicate glass layer thereunder, so that the phosphorus-doped polysilicon layer is partially exposed; Using the remaining phosphosilicate glass layer as a mask, wet etching is performed to remove the exposed phosphorus-doped polysilicon layer and the tunneling oxide layer under the exposed phosphorus-doped polysilicon layer, so that the P-type silicon wafer is partially exposed; The solution used for the wet etching is an alkaline solution.

2. The method for preparing a solar cell according to claim 1, characterized in that: After locally coating the surface of the phosphosilicate glass layer with an acidic etching coating, the method further comprises: The acid etching coating is dried at a temperature of 180 degrees Celsius to 220 degrees Celsius.

3. The method for preparing a solar cell according to claim 1, characterized in that: After locally coating the surface of the phosphosilicate glass layer with an acidic etching coating and before performing wet etching, the method further comprises: The interval time between locally coating the acid etching coating on the surface of the phosphorus silicon glass layer and performing the wet etching is controlled, and the interval time is 10 minutes to 30 minutes.

4. The method for preparing a solar cell according to claim 1, characterized in that: The alkaline solution is a potassium hydroxide solution or a sodium hydroxide solution.

5. The method for preparing a solar cell according to claim 1, characterized in that: The acidic etching coating contains hydrofluoric acid.

6. The method for preparing a solar cell according to any one of claims 1 to 5, characterized in that: After the wet etching, the method further comprises: Acid washing is performed to remove the remaining phosphosilicate glass layer.

7. The method for preparing a solar cell according to claim 6, characterized in that: After the pickling is performed to remove the remaining phosphosilicate glass layer, the method further comprises: A passivation layer is formed on both sides of the P-type silicon wafer.

8. The method for preparing a solar cell according to any one of claims 1 to 5, characterized in that: The step of sequentially stacking a tunnel oxide layer and a polysilicon layer on one side of the P-type silicon wafer comprises: A tunneling oxide layer and a polysilicon layer are sequentially stacked on one side of the P-type silicon wafer by using a low-pressure chemical vapor deposition method.

9. A solar cell, characterized in that: The solar cell is prepared by the method for preparing the solar cell according to any one of claims 1 to 8.

10. The solar cell according to claim 9, characterized in that: The solar cell comprises a back electrode contact silicon solar cell.

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