Photovoltaic cell and method and apparatus for producing same, photovoltaic module

Abstract

This application relates to photovoltaic cells, their fabrication methods and equipment, and photovoltaic modules. The photovoltaic cell fabrication method of this application includes the following steps: providing a silicon substrate, wherein a first surface of the silicon substrate has a first region and a second region; forming a silicon oxide barrier region in the first region by laser oxidation; performing a first diffusion doping on the first surface to form a doped region in the second region; removing the silicon oxide barrier region; and fabricating a first passivation layer on the first region. The photovoltaic cell fabrication method of this application can reduce recombination losses on the front side of the cell, thereby improving the conversion efficiency of the photovoltaic cell.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to photovoltaic cells and their preparation methods and equipment, and photovoltaic modules. Background Technology

[0002] TOPCon cells, short for Tunnel Oxide Passivated Contact photovoltaic cells, are one of the mainstream technologies for high-efficiency crystalline silicon photovoltaic cells. With their high conversion efficiency and promising industrialization prospects, they have become a research and application hotspot in the photovoltaic industry. However, in traditional TOPCon photovoltaic cell fabrication methods, the resulting cells are prone to significant recombination losses on the front side. Summary of the Invention

[0003] Therefore, it is necessary to provide photovoltaic cells, their fabrication methods and equipment, and photovoltaic modules. The photovoltaic cell fabrication method of this application can reduce recombination losses on the front side of the cell, thereby improving the conversion efficiency of the photovoltaic cell.

[0004] In a first aspect, this application provides a method for preparing a photovoltaic cell, comprising the following steps:

[0005] A silicon substrate is provided, wherein a first region and a second region are present on a first surface of the silicon substrate; a silicon oxide barrier region is formed in the first region by laser oxidation process;

[0006] The first surface is subjected to a first diffusion doping process to form a doped region in the second region;

[0007] Remove the silicon oxide barrier region;

[0008] A first passivation layer is prepared on the first region.

[0009] In some embodiments, lasers including infrared lasers and ultraviolet lasers are used to perform laser oxidation treatment on the first region;

[0010] The silicon oxide barrier region includes amorphous oxygen-rich regions and dense regions stacked together, wherein the amorphous oxygen-rich regions penetrate deeper into the silicon substrate than the dense regions; the density of the dense regions is greater than the density of the amorphous oxygen-rich regions.

[0011] In some embodiments, the power of the ultraviolet laser accounts for 25% to 30% of the power of the infrared laser.

[0012] In some embodiments, the wavelength of the infrared laser is 1060nm~1070nm.

[0013] In some embodiments, the wavelength of the ultraviolet laser is 350nm~360nm.

[0014] In some embodiments, the infrared laser has a power of 8W to 15W.

[0015] In some embodiments, the power of the ultraviolet laser is 2W to 5W.

[0016] In some embodiments, the thickness of the amorphous oxygen-rich region is 0.5 nm to 1.5 nm; and the thickness of the dense region is 1.5 nm to 2.5 nm.

[0017] In some embodiments, acid is used to remove the silicon oxide barrier region.

[0018] In some embodiments, hydrogen-containing plasma is also introduced during the process of preparing the first passivation layer on the first region.

[0019] Secondly, this application provides a photovoltaic cell fabrication apparatus, comprising:

[0020] A laser oxidation processing apparatus for forming a silicon oxide barrier region in a first region on a first surface of a silicon substrate by laser oxidation processing;

[0021] A diffusion doping device is used to perform a first diffusion doping on the first surface to form a doped region in a second region on the first surface;

[0022] An etching apparatus for removing the silicon oxide barrier region;

[0023] A passivation device for preparing a first passivation layer on the first region.

[0024] Thirdly, this application provides a photovoltaic cell, prepared by the photovoltaic cell preparation method described in any one of the above-mentioned methods, comprising:

[0025] A silicon substrate having a first region and a second region on a first surface, wherein a first passivation layer is disposed on the first region and a doped region is disposed in the second region.

[0026] In some embodiments, the silicon substrate has a second surface disposed opposite to the first surface; the second surface has a tunneling oxide layer and a doped layer stacked thereon; the tunneling oxide layer is located between the doped layer and the silicon substrate; the doping type of the doped layer and the doped region are different.

[0027] Fourthly, this application provides a photovoltaic module, comprising:

[0028] Cover plate;

[0029] At least one battery string, the battery string comprising a photovoltaic cell prepared by the method described in any one of the above-mentioned photovoltaic cell preparation methods, or a photovoltaic cell described in any one of the above-mentioned photovoltaic cell preparation methods;

[0030] And an encapsulation layer, which is located between the cover plate and the battery string, and the cover plate is connected to the battery string through the encapsulation layer.

[0031] In the aforementioned photovoltaic cell fabrication method, laser oxidation treatment can form a silicon oxide barrier region in the first region, thereby blocking the diffusion of dopant atoms. This ensures that during the first diffusion doping of the first surface, patterned doped regions are formed only in the second region. After removing the silicon oxide barrier region, doped regions are obtained only in the metal regions, while the non-metal regions are free of doped regions, reducing non-radiative recombination in the photovoltaic cell. Fabricating a first passivation layer on the first region can repair silicon lattice defects formed during the laser oxidation treatment and the removal of the silicon oxide barrier region. In other words, the photovoltaic cell fabrication method of this application can reduce recombination losses on the front side of the cell, thereby improving the conversion efficiency of the photovoltaic cell. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of a structure in which a silicon oxide barrier region is formed in the first region by laser oxidation treatment;

[0033] Figure 2 In order to be in Figure 1 A schematic diagram of a structure in which a doped region is formed in the second region based on the structure shown;

[0034] Figure 3 In order to be in Figure 2 A schematic diagram of a structure with the silicon oxide barrier region removed from the structure shown;

[0035] Figure 4 In order to be in Figure 3 A schematic diagram of a structure in which a first passivation layer is fabricated on a first region based on the structure shown;

[0036] Figure 5 This is a schematic diagram of the structure of a photovoltaic cell provided in one embodiment of this application;

[0037] Figure 6 A schematic flowchart illustrating a method for preparing a photovoltaic cell according to an embodiment of this application;

[0038] Figure 7 This is a schematic diagram of the structure of a photovoltaic module provided in one embodiment of this application.

[0039] Explanation of reference numerals in the attached figures:

[0040] 10-Silicon substrate; 20-Silicon oxide barrier region; 30-Doped region; 40-First passivation layer; 50-First electrode; 60-Tunneling oxide layer; 70-Doped layer; 80-Second electrode; 100-Cover plate; 200-Battery string; 300-Encapsulation layer. Detailed Implementation

[0041] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description of specific embodiments of this application is provided below. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0043] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0044] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0045] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0046] Reference Figures 1-4 As shown, one embodiment of this application provides a method for preparing a photovoltaic cell, comprising the following steps:

[0047] A silicon substrate 10 is provided, and a first region and a second region are provided on a first surface of the silicon substrate 10; a silicon oxide barrier region 20 is formed in the first region by laser oxidation process;

[0048] A first diffusion doping is performed on the first surface to form a doped region 30 in the second region;

[0049] Remove the silica barrier region 20;

[0050] A first passivation layer 40 is prepared on the first region.

[0051] In the aforementioned photovoltaic cell fabrication method, laser oxidation treatment can form a silicon oxide barrier region 20 in the first region, thereby blocking the diffusion of dopant atoms. This ensures that during the first diffusion doping of the first surface, patterned doped regions 30 are formed only in the second region. After removing the silicon oxide barrier region 20, doped regions 30 are obtained only in the metal regions, while non-metal regions do not have doped regions 30, reducing non-radiative recombination in the photovoltaic cell. Fabricating a first passivation layer 40 on the first region can repair silicon lattice defects formed during the laser oxidation treatment and removal of the silicon oxide barrier region 20. Therefore, the photovoltaic cell fabrication method of this application can reduce recombination losses on the front side of the cell, thereby improving the conversion efficiency of the photovoltaic cell.

[0052] Reference Figure 6 As shown, in some embodiments, the method for preparing a photovoltaic cell includes the following steps:

[0053] S10, a silicon substrate 10 is provided, the first surface of the silicon substrate 10 having a first region and a second region; a silicon oxide barrier region 20 is formed in the first region by laser oxidation process;

[0054] Reference Figure 1 As shown, Figure 1 This is a schematic diagram of a structure in which a silicon oxide barrier region 20 is formed in the first region by laser oxidation treatment.

[0055] In some embodiments, lasers including infrared lasers and ultraviolet lasers are used to perform laser oxidation treatment on the first region;

[0056] The silicon oxide barrier region 20 includes amorphous oxide-rich regions and dense regions stacked together. The amorphous oxide-rich regions penetrate deeper into the silicon substrate 10 than the dense regions. The density of the dense regions is greater than that of the amorphous oxide-rich regions.

[0057] Laser oxidation of the first region using both infrared and ultraviolet lasers can form a gradient silicon oxide barrier region 20. The infrared laser heats the silicon substrate, promoting the oxidation reaction, while the ultraviolet laser, with its high photon energy, promotes densification of the surface layer of the silicon oxide barrier region 20, thereby increasing its density. This results in a stacked amorphous oxygen-rich region and a dense region, where the amorphous oxygen-rich region penetrates deeper into the silicon substrate 10 than the dense region, and the density of the dense region is greater than that of the amorphous oxygen-rich region. It is understood that density in this application refers to the structural density of the material; higher density indicates lower porosity, denser atomic arrangement, and better stability. Density is measured using a chemical immersion etching method. By measuring the electrochemical parameters of the silicon oxide barrier region 20 in an electrolyte solution, such as corrosion current density and film resistance, its corrosion resistance can be evaluated, indirectly reflecting its density. The amorphous oxygen-rich region located in the inner layer can improve the cross-sectional passivation of the silicon substrate 10, while the dense region located on the surface layer can have a good blocking effect on diffused atoms.

[0058] In some implementations, the power of the ultraviolet laser accounts for 25% to 30% of the power of the infrared laser.

[0059] Within the aforementioned range of the ratio of ultraviolet laser power to infrared laser power, it is easier to improve the density of the silicon oxide blocking region 20, thereby achieving a better blocking effect for diffusion atoms, such as boron atoms, and thus forming a good patterned doping effect. Optionally, the ratio of ultraviolet laser power to infrared laser power is 25%, 26%, 27%, 28%, 29%, or 30%, or the ratio can be within any two of the above-mentioned ratios.

[0060] In some embodiments, the wavelength of the infrared laser is 1060nm~1070nm.

[0061] Optionally, the wavelength of the infrared laser is 1060nm, 1061nm, 1062nm, 1063nm, 1064nm, 1065nm, 1066nm, 1067nm, 1068nm, 1069nm or 1070nm, or the wavelength of the infrared laser may be within the range of any two of the above wavelengths.

[0062] In some of these embodiments, the wavelength of the ultraviolet laser is 350nm~360nm.

[0063] Optionally, the wavelength of the ultraviolet laser is 350nm, 351nm, 352nm, 353nm, 354nm, 355nm, 356nm, 357nm, 358nm, 359nm or 360nm, or the wavelength of the ultraviolet laser can be within the range of any two of the above wavelengths.

[0064] In some embodiments, the infrared laser has a wavelength of 1064 nm and the ultraviolet laser has a wavelength of 355 nm.

[0065] In some implementations, the infrared laser has a power of 8W to 15W.

[0066] In some implementations, the power of the ultraviolet laser is 2W to 5W.

[0067] Within the power range of the aforementioned infrared and ultraviolet lasers, it is convenient to achieve oxidation of the silicon substrate 10 rather than etching using lasers, while simultaneously obtaining a high-density silicon oxide barrier region 20. Optionally, the power of the infrared laser is 8W, 9W, 10W, 11W, 12W, 13W, 14W, or 15W, or the power of the infrared laser can also be within the range of any two of the aforementioned power values. Optionally, the power of the ultraviolet laser is 2W, 2.5W, 3W, 3.5W, 4W, 4.5W, or 5W, or the power of the ultraviolet laser can also be within the range of any two of the aforementioned power values.

[0068] In some embodiments, the infrared laser has a power of 10W and the ultraviolet laser has a power of 3W.

[0069] In some embodiments, the thickness of the amorphous oxygen-rich region is 0.5 nm to 1.5 nm; the thickness of the dense region is 1.5 nm to 2.5 nm.

[0070] Optionally, the thickness of the amorphous oxygen-rich region is 0.5 nm, 0.6 nm, 0.7 nm, 0.8 nm, 0.9 nm, 1 nm, 1.1 nm, 1.2 nm, 1.3 nm, 1.4 nm, or 1.5 nm; alternatively, the thickness of the amorphous oxygen-rich region may fall within any two of the aforementioned thicknesses. Optionally, the thickness of the dense region is 1.5 nm, 1.6 nm, 1.7 nm, 1.8 nm, 1.9 nm, 2 nm, 2.1 nm, 2.2 nm, 2.3 nm, 2.4 nm, or 2.5 nm; alternatively, the thickness of the dense region may fall within any two of the aforementioned thicknesses.

[0071] In some embodiments, the diameter of the scanning spot in the laser oxidation process is 10 μm to 30 μm.

[0072] In some embodiments, the scanning speed of the laser oxidation process is 5 mm / s to 50 mm / s.

[0073] In some embodiments, the laser oxidation process has a spot overlap rate of 85% to 90%.

[0074] In some embodiments, the laser oxidation process is carried out in a mixed atmosphere of oxygen and nitrogen.

[0075] In some embodiments, the ambient oxygen partial pressure during laser oxidation treatment is 25% to 35%.

[0076] Within the range of parameters for the aforementioned laser oxidation treatments, and by combining the parameters of infrared and ultraviolet lasers, it is easy to prepare an oxidation barrier region with good density and high preparation precision.

[0077] Optionally, the diameter of the scanning spot in the laser oxidation process is 10μm, 12μm, 15μm, 18μm, 20μm, 22μm, 25μm, 28μm or 30μm, or the diameter of the scanning spot in the laser oxidation process can be within any two of the above diameters.

[0078] Optionally, the scanning speed of the laser oxidation process is 5 mm / s, 10 mm / s, 15 mm / s, 20 mm / s, 25 mm / s, 30 mm / s, 35 mm / s, 40 mm / s, 45 mm / s or 50 mm / s, or the scanning speed of the laser oxidation process can be within the range of any two of the above speeds.

[0079] Optionally, the overlap rate of the laser oxidation treatment spot is 85%, 86%, 87%, 88%, 89%, or 90%, or the overlap rate of the laser oxidation treatment spot can be within the range of any two of the above overlap rates.

[0080] Optionally, the partial pressure of oxygen in the environment for laser oxidation treatment is 25%, 27%, 29%, 30%, 31%, 33%, or 35%, or the partial pressure of oxygen in the environment for laser oxidation treatment can be within the range of any two of the above partial pressures.

[0081] In some embodiments, the density of the oxidation barrier region is 2.25 g / cm³. 3 ~2.35g / cm 3 .

[0082] It is understood that the density of the oxide barrier region refers to the average density of the entire oxide barrier region. The laser oxidation process of this application can prepare an oxide barrier region with a high density, close to that of thermally oxidized silicon dioxide, which can effectively block the diffusion of boron atoms. Optionally, the density of the oxide barrier region is 2.25 g / cm³. 3 2.27 g / cm 3 2.29 g / cm 3 2.3g / cm 3 2.31 g / cm 3 2.33 g / cm 3 Or 2.35g / cm 3 Alternatively, the density of the oxidation barrier region can also be within the range of any two of the above densities.

[0083] In some embodiments, before forming the silicon oxide barrier region 20 in the first region by laser oxidation, the process further includes texturing the surface of the silicon substrate 10 with an alkaline solution to form a pyramid structure.

[0084] In some embodiments, the alkaline solution comprises a KOH solution with a mass percentage of 1 wt% to 5 wt%.

[0085] Optionally, the mass percentage of the KOH solution is 1 wt%, 2 wt%, 3 wt%, 4 wt%, or 5 wt%, or the mass percentage of the KOH solution may be within the range of any two of the above mass percentages.

[0086] In some embodiments, the temperature of the flocking process is 70°C to 90°C.

[0087] Optionally, the temperature for the flocking process is 70°C, 72°C, 75°C, 78°C, 80°C, 82°C, 85°C, 88°C, or 90°C, or the temperature for the flocking process can be within any two of the above temperatures.

[0088] In some embodiments, the texturing process takes 480s to 520s.

[0089] Optionally, the texturing process time is 480s, 485s, 490s, 495s, 500s, 505s, 510s, 515s, or 520s, or the texturing process time can be within any two of the above times.

[0090] S20. Perform first diffusion doping on the first surface to form a doped region 30 in the second region;

[0091] Reference Figure 1 As shown, Figure 2 In order to be in Figure 1 The diagram shows a structure in which a doped region 30 is formed in the second region based on the structure shown.

[0092] In some embodiments, the doping element of the doped region 30 includes at least one of boron, aluminum, gallium, and indium.

[0093] In some embodiments, the temperature of the first diffusion doping is 800°C to 1000°C.

[0094] Optionally, the temperature for the first diffusion doping is 800℃, 820℃, 850℃, 880℃, 900℃, 920℃, 950℃, 980℃ or 1000℃, or the temperature for the first diffusion doping can be within the range of any two of the above temperatures.

[0095] In some embodiments, the sheet resistance of the doped region 30 is 155 Ω / sq to 175 Ω / sq.

[0096] Optionally, the sheet resistance of the doped region 30 is 155Ω / sq, 158Ω / sq, 160Ω / sq, 162Ω / sq, 165Ω / sq, 168Ω / sq, 170Ω / sq, 172Ω / sq or 175Ω / sq, or the sheet resistance of the doped region 30 may be within the range of any two of the above sheet resistances.

[0097] S30, Remove silica barrier zone 20;

[0098] Reference Figure 3 As shown, Figure 3 In order to be in Figure 2 A schematic diagram of the structure shown, with the silicon oxide blocking region 20 removed.

[0099] In some embodiments, a mixture of HF and HNO3 is used to remove the silica barrier region 20.

[0100] While removing the silicon oxide barrier region 20 using a mixture of HF and HNO3, the borosilicate glass layer on the surface of the doped region 30 can also be removed simultaneously.

[0101] In some embodiments, the volume ratio of HF to HNO3 is 1:(3~4).

[0102] Optionally, the volume ratio of HF to HNO3 is 1:3, 1:3.2, 1:3.4, 1:3.6, 1:3.8 or 1:4, or the volume ratio of HF to HNO3 can be within the range of any two of the above volume ratios.

[0103] In some of these embodiments, the mass concentration of HF is 1% to 49%.

[0104] Optionally, the mass concentration of HF is 1%, 5%, 10%, 20%, 30%, 40%, or 49%, or the mass concentration of HF may be within the range of any two of the above mass concentrations.

[0105] In some of these embodiments, the mass concentration of HNO3 is 20% to 70%.

[0106] Optionally, the mass concentration of HNO3 is 20%, 30%, 40%, 50%, 60% or 70%, or the mass concentration of HNO3 may be within the range of any two of the above mass concentrations.

[0107] S40. A first passivation layer 40 is prepared on the first region.

[0108] Reference Figure 4 As shown, Figure 4 In order to be in Figure 3 A schematic diagram of a structure in which a first passivation layer 40 is fabricated on a first region based on the structure shown;

[0109] In some embodiments, the first passivation layer 40 comprises aluminum oxide.

[0110] In some embodiments, the thickness of the first passivation layer 40 is 3 nm to 7 nm.

[0111] Optionally, the thickness of the first passivation layer 40 is 3nm to 7nm, or the thickness of the first passivation layer 40 can be within any two of the above-mentioned thicknesses.

[0112] In some embodiments, hydrogen-containing plasma is also introduced during the deposition of the first passivation layer 40 of alumina.

[0113] During the deposition of the first passivation layer 40 of alumina, hydrogen-containing plasma, such as a mixture of H2 and N2 gas, is also introduced. This has a good effect on repairing silicon lattice defects caused by laser thermal effects and can further improve the minority carrier lifetime of non-metallic regions.

[0114] In some embodiments, acid is used to remove the silicon oxide barrier region 20.

[0115] In some embodiments, hydrogen-containing plasma is also introduced during the preparation of the first passivation layer 40 on the first region.

[0116] Another embodiment of this application provides a photovoltaic cell fabrication apparatus, comprising:

[0117] A laser oxidation processing apparatus is used to form a silicon oxide barrier region 20 in a first region on a first surface of a silicon substrate 10 by laser oxidation processing;

[0118] A diffusion doping device is used to perform a first diffusion doping on a first surface, forming a doped region 30 in a second region on the first surface;

[0119] Etching apparatus for removing silicon oxide barrier region 20;

[0120] A passivation device for preparing a first passivation layer 40 on a first region.

[0121] Another embodiment of this application provides a photovoltaic cell, prepared by any of the photovoltaic cell preparation methods described above, comprising:

[0122] The silicon substrate 10 has a first region and a second region on its first surface. A first passivation layer 40 is disposed on the first region, and a doped region 30 is disposed on the second region.

[0123] Reference Figure 5 As shown, in some embodiments, the silicon substrate 10 has a second surface disposed opposite to the first surface; the second surface has a tunneling oxide layer 60 and a doped layer 70 stacked thereon; the tunneling oxide layer 60 is located between the doped layer 70 and the silicon substrate 10; the doping types of the doped layer 70 and the doped region 30 are different.

[0124] In some embodiments, the doped region 30 is P-type doped and the doped layer 70 is N-type doped.

[0125] In some embodiments, the photovoltaic cell further includes a first electrode 50 and a second electrode 80; the first electrode 50 is electrically connected to the doped region 30, and the second electrode 80 is electrically connected to the doped layer 70.

[0126] Another embodiment of this application provides a photovoltaic module, including:

[0127] Cover plate 100;

[0128] At least one battery string 200, the battery string 200 comprising a photovoltaic cell prepared by any of the above-mentioned photovoltaic cell preparation methods, or a photovoltaic cell prepared by any of the above-mentioned methods.

[0129] And an encapsulation layer 300, which is located between the cover plate 100 and the battery string 200, and the cover plate 100 is connected to the battery string 200 through the encapsulation layer 300.

[0130] The following is the specific implementation:

[0131] Example 1

[0132] Methods for preparing photovoltaic cells:

[0133] (1) Texturing: The silicon substrate was treated with a 2wt% KOH alkaline solution at 80°C for 500s to form a double-sided pyramid textured surface;

[0134] (2) Laser selective oxidation: A dual-wavelength laser system is used, with an infrared laser wavelength of 1064nm and a power of 10W, and an ultraviolet laser wavelength of 355nm and a power of 3W. The non-metallic region is scanned according to the grid pattern. The scanning speed is controlled at 25mm / s to form a silicon oxide blocking region 20 on the surface of the silicon substrate 10. The outer layer is a dense region with a thickness of 2nm, and the inner layer is an amorphous oxygen-rich region with a thickness of 1nm.

[0135] (3) Boron diffusion and etching: Boron diffusion is carried out at 900℃, and P is formed in the metal region. + Layer; the silicon oxide barrier layer and the borosilicate glass layer in the non-metallic region were etched away using a mixture of HF and HNO3 with a volume ratio of 10:32.

[0136] (4) Backside structure fabrication: A tunneling oxide layer 60 with a thickness of 1.5 nm and a phosphorus-doped polycrystalline silicon layer with a thickness of 140 nm are deposited on the backside of the silicon substrate 10; an aluminum oxide passivation layer with a thickness of 5 nm is deposited on the non-metallic region on the front side of the silicon substrate 10.

[0137] (5) Print silver paste and sinter to prepare front and back electrodes.

[0138] Comparative Example 1

[0139] Photovoltaic cell fabrication:

[0140] In Comparative Example 1, the difference between the photovoltaic cell preparation method and the photovoltaic cell preparation method in Example 1 is only that step (2) is not performed, and boron diffusion is performed on the entire surface in step (3).

[0141] The photovoltaic cells prepared in Example 1 and Comparative Example 1 were tested, and the test results are shown in the table below:

[0142]

[0143] As can be seen, the photovoltaic cell preparation method in Example 1 of this application enables the prepared photovoltaic cell to have a lower recombination loss, a significantly lower recombination current density compared to Comparative Example 1, and the absence of doping in the non-metallic region can improve the open-circuit voltage, thereby achieving a higher conversion efficiency of the photovoltaic cell.

[0144] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0145] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A method for preparing a photovoltaic cell, characterized in that, Includes the following steps: A silicon substrate is provided, wherein a first region and a second region are present on a first surface of the silicon substrate; a silicon oxide barrier region is formed in the first region by laser oxidation process; The first surface is subjected to a first diffusion doping process to form a doped region in the second region; Remove the silicon oxide barrier region; A first passivation layer is prepared on the first region.

2. The method for preparing a photovoltaic cell according to claim 1, characterized in that, Laser oxidation treatment of the first region is performed using lasers including infrared lasers and ultraviolet lasers; The silicon oxide barrier region includes amorphous oxygen-rich regions and dense regions stacked together, wherein the amorphous oxygen-rich regions penetrate deeper into the silicon substrate than the dense regions; the density of the dense regions is greater than the density of the amorphous oxygen-rich regions.

3. The method for preparing a photovoltaic cell according to claim 2, characterized in that, The power of the ultraviolet laser accounts for 25% to 30% of the power of the infrared laser.

4. The method for preparing a photovoltaic cell according to claim 3, characterized in that, The wavelength of the infrared laser is 1060nm~1070nm; and / or, The wavelength of the ultraviolet laser is 350nm~360nm; and / or, The infrared laser has a power of 8W to 15W; and / or, The power of the ultraviolet laser is 2W~5W.

5. The method for preparing a photovoltaic cell according to claim 2, characterized in that, The thickness of the amorphous oxygen-rich region is 0.5 nm to 1.5 nm; the thickness of the dense region is 1.5 nm to 2.5 nm.

6. The method for preparing a photovoltaic cell according to any one of claims 1 to 5, characterized in that, The silicon oxide barrier region is removed using an acid solution; and / or, During the process of preparing the first passivation layer on the first region, hydrogen-containing plasma is also introduced.

7. A photovoltaic cell manufacturing apparatus, characterized in that, include: A laser oxidation processing apparatus for forming a silicon oxide barrier region in a first region on a first surface of a silicon substrate by laser oxidation processing; A diffusion doping device is used to perform a first diffusion doping on the first surface to form a doped region in a second region on the first surface; An etching apparatus for removing the silicon oxide barrier region; A passivation device for preparing a first passivation layer on the first region.

8. A photovoltaic cell, characterized in that, The photovoltaic cell is prepared by the method described in any one of claims 1 to 6, comprising: A silicon substrate having a first region and a second region on a first surface, wherein a first passivation layer is disposed on the first region and a doped region is disposed in the second region.

9. The photovoltaic cell according to claim 8, characterized in that, The silicon substrate has a second surface disposed opposite to the first surface; the second surface has a tunneling oxide layer and a doped layer stacked thereon; the tunneling oxide layer is located between the doped layer and the silicon substrate; the doping type of the doped layer and the doped region are different.

10. A photovoltaic module, characterized in that, include: Cover plate; At least one battery string, the battery string comprising a photovoltaic cell prepared by the method of any one of claims 1 to 6, or a photovoltaic cell prepared by any one of claims 8 to 9; And an encapsulation layer, which is located between the cover plate and the battery string, and the cover plate is connected to the battery string through the encapsulation layer.

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