Passivation structure for cell cut surface and preparation method thereof, solar cell

Abstract

This invention provides a method for preparing a passivation structure for a cut surface of a battery cell, comprising: providing a crystalline silicon battery cell having a cut surface, the cut surface being a side surface formed by slicing; controlling the surface temperature of the cut surface within a range of 25°C to 400°C; forming a first passivation film on the cut surface; and forming a second passivation film on the first passivation film; wherein the surface defect state density of the first passivation film is in the range of 1.0*10^6. 8 eV ‑1 cm ‑2 Up to 1.0*10 11 eV ‑1 cm ‑2 The charge density of the second passivation film ranges from 1.0 to 10^6. 8 eV ‑1 cm ‑2 Up to 1.0*10 11 eV ‑1 cm ‑2 Between. The embodiments of the present invention are beneficial for improving the photoelectric conversion efficiency of the cut surface.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of solar cells, and in particular to a passivation structure for a cut surface of a cell, a preparation method thereof, and a solar cell. Background Art

[0002] In recent years, photovoltaic power generation technology, as the mainstream technology for utilizing solar energy resources, is an important field for the development of green energy and has moved towards marketization and commercialization. With the continuous advancement of technology, the development goal of photovoltaic module products is to continuously increase the output power. For example, the use of half-cell, stacked shingles, stacked welding and other module technologies can reduce or even eliminate the spacing between strings inside the battery string, increase the effective area, and reduce the current of the circuit within the string, thereby reducing the circuit transmission loss. Among them, both half-cell photovoltaic modules and stacked photovoltaic modules require the solar cells to be cut during production, that is, the complete square-like cells (with large / small chamfers) are cut into small pieces of cells, and then the cell strings are formed through the intra-string interconnection technology, followed by a series of subsequent component production and manufacturing processes such as string swinging, testing, lamination, and frame installation. At present, laser scribing is often used to form gullies, and then physical means are used to further break the cells for cell cutting.

[0003] However, the photoelectric conversion efficiency of the small cells processed by this cutting method is reduced. Therefore, how to provide a method to avoid the problem of reduced photoelectric conversion efficiency of cells caused by cutting has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0004] The embodiment of the present invention provides a method for preparing a passivation structure for a cell cut surface, which can improve the photoelectric conversion efficiency of a cut crystalline silicon cell.

[0005] In order to solve the above problems, an embodiment of the present invention provides a method for preparing a passivation structure for a cell cut surface, comprising: providing a crystalline silicon cell, wherein the crystalline silicon cell has a cut surface, and the cut surface is a side surface formed by slices; controlling the surface temperature range of the cut surface to be between 25°C and 400°C; forming a first passivation film on the cut surface; forming a second passivation film on the first passivation film; wherein the surface defect state density of the first passivation film is in the range of 1.0*10 8 eV -1 cm -2 Up to 1.0*10 11 eV -1 cm -2 The charge density of the second passivation film is in the range of 1.0*10 10 cm -2 Up to 1.0*10 14 cm -2 between.

[0006] The embodiment of the present invention further provides a passivation structure, which is applied to the cut surface of a crystalline silicon cell, and the passivation structure comprises: a first passivation film and a second passivation film; the first passivation film is located between the cut surface and the second passivation film; wherein the surface defect state density of the first passivation film is in the range of 1.0*10 8 eV -1 cm -2 Up to 1.0*10 11 eV -1 cm -2 The charge density of the second passivation film is in the range of 1.0*10 10 cm -2 Up to 1.0*10 14 cm -2 between.

[0007] An embodiment of the present invention also provides a solar cell, which includes: a crystalline silicon substrate; a front passivation film layer and a front electrode are arranged on the front side of the crystalline silicon substrate; a back passivation film layer and a back electrode are arranged on the back side of the crystalline silicon substrate; and the above-mentioned passivation structure is arranged on at least one side of the crystalline silicon substrate serving as a cutting surface.

[0008] Compared with the related art, the surface defect state density of the first passivation film is set at 1.0*10 8 eV -1 cm -2 Up to 1.0*10 11 eV -1 cm -2 It is beneficial to improve the crystal matching of the first passivation film and the silicon substrate of the crystalline silicon cell, reduce the interface state defect density, saturate the dangling bonds of the silicon substrate, thereby reducing the carrier recombination rate and improving the photoelectric conversion efficiency of the crystalline silicon cell; accordingly, the charge density of the second passivation film is set at 1.0*10 10 cm -2 Up to 1.0*10 14 cm -2 The cut surface can be field passivated to further suppress the recombination of carriers and improve the photoelectric conversion efficiency.

[0009] In addition, the provision of the second passivation film can also prevent the first passivation film from being oxidized, which is beneficial to slowing down the attenuation of battery performance; at the same time, in the process of preparing the passivation structure, the cut surface of the crystalline silicon cell is in a lower temperature range, which is beneficial to avoid the problem of reduced photoelectric conversion efficiency caused by secondary heating of the crystalline silicon cell.

[0010] In addition, the use of the same magnetron sputtering device to achieve the coordinated preparation of the first passivation film and the second passivation film not only helps to reduce hardware costs, but also avoids the need to move the battery cell from the chamber of one device to the chamber of another device when different passivation film layers are prepared in different magnetron sputtering devices, causing the temperature of the cut surface of the silicon wafer to be unstable and affecting the quality of the film layer.

[0011] In addition, the higher the sputtering gas concentration, the higher the coating rate, and the higher the oxygen concentration, the more conducive it is to reactive sputtering with the sputtered target atoms. Controlling the ratio of sputtering gas and oxygen within this range can ensure both the quality and efficiency of the coating.

[0012] In addition, the higher the target power, the faster the coating speed, and the lower the target power, the more uniform the formed film. Setting the target power range during the sputtering process within the above range can not only ensure the film formation speed, but also make the surface of the plated film uniform; adjusting the gas pressure within this range can ensure the film formation speed and film formation quality; adjusting the sputtering time within the above range and combining the film formation speed can control the film thickness so that the passivation film of this thickness can effectively improve the photoelectric conversion efficiency.

[0013] In addition, wrapping the surfaces other than the cut surface before forming the first passivation film is helpful to prevent the formation process of the first passivation film from causing contamination or damage to other surfaces.

[0014] In addition, controlling the thickness of the first passivation film within this range can not only ensure the passivation effect of the first passivation film, but also help avoid weakening the field passivation effect of the second passivation film; setting the thickness range of the second passivation film within this range, on the one hand, can avoid the passivation efficiency being reduced due to the passivation film being too thin, and on the other hand, avoid the passivation film being too thick resulting in excessively high preparation costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0016] Figure 1 A schematic diagram of the structure of the passivation structure provided in the embodiment of the present application;

[0017] Figure 2 A schematic diagram of a magnetron sputtering device provided in an embodiment of the present application;

[0018] Figure 3 A schematic diagram of experimental results provided for the embodiments of the present application;

[0019] Figure 4A schematic structural diagram of a solar cell with a passivation structure provided in an embodiment of the present application. DETAILED DESCRIPTION

[0020] As can be seen from the background technology, during the production process, when the whole cell is cut by the cutting process, it is very easy to cause serious damage on the cut surface of the cell, such as laser damage. The damage on the cut surface will become the recombination center of photogenerated carriers. Therefore, compared with the cell that has not been cut, the photoelectric conversion efficiency of the cut crystalline silicon solar cell is often reduced.

[0021] In order to solve the above problems, an embodiment of the present invention provides a method for preparing a passivation structure for a cell cut surface. The embodiment of the present invention forms a first passivation film on the cut surface of a crystalline silicon cell. The surface defect state density of the first passivation film is 1.0*10 8 eV -1 cm -2 Up to 1.0*10 11 eV -1 cm -2 The cut surface is chemically passivated, which is beneficial to improve the crystal matching of the first passivation film and the silicon substrate of the crystalline silicon cell, reduce the interface state defect density, saturate the dangling bonds of the silicon substrate, thereby reducing the carrier recombination rate and improving the photoelectric conversion efficiency of the crystalline silicon cell; at the same time, a second passivation film is formed on the first passivation film, and the charge density of the second passivation film is 1.0*10 10 cm -2 Up to 1.0*10 14 cm -2 In order to perform field passivation on the cut surface, the recombination of carriers is further suppressed and the photoelectric conversion efficiency is improved.

[0022] In addition, the provision of the second passivation film can also prevent the first passivation film from being oxidized, which is beneficial to slowing down the attenuation of battery performance; at the same time, in the process of preparing the passivation structure, the cut surface of the crystalline silicon cell is in a lower temperature range, which is beneficial to avoid the problem of reduced photoelectric conversion efficiency caused by secondary heating of the crystalline silicon cell.

[0023] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that in the embodiments of the present invention, many technical details are provided to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed in the present application can be implemented.

[0024] An embodiment of the present invention provides a method for preparing a passivation structure for a cut surface of a battery. The preparation method comprises the following steps:

[0025] Step 1, providing a crystalline silicon cell sheet, wherein the crystalline silicon cell sheet has a cutting surface, and the cutting surface is a side surface formed by slicing.

[0026] The cutting surface of this embodiment can be formed by cutting the initial cell, that is, by cutting the initial cell to form a plurality of small cells with cutting surfaces. The cell can be a crystalline silicon solar cell. In some embodiments, the initial cell can have different specifications and sizes, for example: 158mm*158mm, 163mm*163mm, 182mm*182mm, 210mm*210mm, etc.

[0027] When cutting the initial cell, the cell can be cut along the grid line area parallel to the initial cell to form a small cell. Optionally, the initial cell can be cut into two equal parts, three equal parts, four equal parts, five equal parts, six equal parts, etc. to form the above-mentioned small cell. As an example, the cell after cutting in the present invention is a two-element cell, that is, a half cell.

[0028] The half-cell cell may be: a P-PERC half-cell cell, a P-TOPcon half-cell cell, an N-PERT half-cell cell, an N-TOPcon half-cell cell, an HJT half-cell cell, etc. This embodiment does not limit the specific type of crystalline silicon cell.

[0029] It is worth mentioning that the preparation method of the passivation structure of the present application is not only applicable to the cut surface after laser cutting, but also applicable to the passivation of the cut surface caused by other physical or chemical cutting methods, and the present application is not limited to this.

[0030] Step 2, controlling the surface temperature of the cut surface between 25 degrees Celsius and 400 degrees Celsius.

[0031] In some embodiments, the cut surface can be directly heated by a heating source, or the cut surface can be heated by a high-temperature gas atmosphere to control the surface temperature of the cut surface; as the temperature of the cut surface gradually increases, the passivation film formed on the surface of the cut surface shows a trend of transformation from an amorphous phase to a crystalline phase, and the passivation effect of the passivation film increases. In some embodiments, the temperature of the cut surface is controlled within the range of 25 to 400 degrees, which can not only ensure that the passivation film has a good passivation effect, but also help to slow down the attenuation of the performance of the crystalline silicon cell caused by the high process temperature.

[0032] Preferably, the temperature range is between 150 degrees Celsius and 350 degrees Celsius. When the temperature is higher than 350 degrees, the performance of the crystalline silicon cell will be attenuated, and when the temperature is lower than 150 degrees, it is not conducive to promoting the transition of the passivation film to the crystalline phase. Therefore, within this temperature range, on the one hand, since it is conducive to promoting the transition of the formed passivation film to the crystalline phase within this temperature range, the passivation effect of the passivation film can be guaranteed, and on the other hand, the performance attenuation problem of the crystalline silicon cell caused by high-temperature heat treatment can be avoided, thereby effectively improving the photoelectric conversion efficiency of the cut crystalline silicon cell.

[0033] Step 3: forming a first passivation film on the cut surface.

[0034] Reference Figure 1 As shown, the first passivation film 101 is formed on the cut surface, and the surface defect state density of the first passivation film 101 is 1.0*10 8 eV -1 cm -2 Up to 1.0*10 11 eV -1 cm -2 The first passivation film 101 with the above surface defect state density can chemically passivate the cut surface, improve the crystal type matching with the silicon substrate of the crystalline silicon cell, reduce the interface state density, and saturate the dangling bonds of the silicon substrate, thereby reducing the carrier recombination rate and improving the photoelectric conversion efficiency of the crystalline silicon cell.

[0035] Optionally, the material of the first passivation film 101 may be amorphous silicon.

[0036] Optionally, the thickness of the first passivation film 101 can be controlled within a range of 1 nm to 20 nm. If the first passivation film 101 is too thin, the passivation effect of the first passivation film 101 will be poor; if the first passivation film is too thick, the second passivation film 102 will be too far away from the cutting surface, thereby weakening the field passivation effect of the second passivation film 102. In other words, controlling the thickness of the first passivation film 101 within this range can ensure the passivation effect of the first passivation film 101 and help avoid weakening the field passivation effect of the second passivation film 102.

[0037] In some embodiments, before forming the first passivation film, a fixture may be used to wrap the surfaces of the crystalline silicon cell except the cut surface, leaving only the cut surface exposed. The fixture may be a graphite fixture, a quartz fixture, a SIC fixture, a stainless steel fixture, etc. This is helpful to prevent the formation process of the first passivation film from causing contamination or damage to other surfaces.

[0038] In some embodiments, a first magnetron sputtering process is performed by a magnetron sputtering device to form a first passivation film 101. The first magnetron sputtering process parameters include: a target power of 50W to 200W, a sputtering time of 5min to 20min, and an air pressure environment of 0.1Pa to 10Pa. In the coating process, the higher the target power, the faster the coating speed, and the lower the target power, the more uniform the formed film. Setting the target power range in the sputtering process between 50W and 300W can ensure a faster film forming speed and a more uniform film surface. Accordingly, as the air pressure in the vacuum chamber increases, the film deposition rate tends to increase first and then decrease. The lower the air pressure in the vacuum chamber, the looser the coated film layer. Adjusting the air pressure within the above range can ensure a higher film forming rate and the quality of the coated film layer. Further, adjusting the sputtering time within the range, combined with the film forming speed, and controlling the film thickness are beneficial to improving the passivation effect of the first passivation film 101 and the second passivation film 102.

[0039] Reference Figure 2 As shown, the magnetron sputtering device for performing the magnetron sputtering process may include a target material, a magnetron sputtering vacuum chamber 201, etc. Before using the magnetron sputtering vacuum chamber, it can be cleaned with an inert gas to remove the adsorbed gas in the pipeline and the magnetron sputtering vacuum chamber, and the chamber can be maintained at a certain vacuum degree before sputtering, such as between 0.1Pa-5Pa. Before using the target material for film coating, the target material can be sputtered for a preset time, such as between 5min-15min, so as to remove impurities on the target material and avoid impurities in the formed passivation film.

[0040] The magnetron sputtering process can adopt one or more of single target independent, multiple targets in turn, combined co-sputtering, etc. This application does not specifically limit the magnetron sputtering power supply, and different types of sputtering processes can be adopted as needed, such as: DC magnetron sputtering, medium frequency magnetron sputtering, radio frequency magnetron sputtering, etc. Further, magnetron sputtering, reactive sputtering, medium frequency sputtering and other sputtering processes can be used alone or in combination according to process requirements.

[0041] In some embodiments, the formed first passivation film is an amorphous silicon passivation film.

[0042] When the first passivation film is an amorphous silicon passivation film, the target material of the first magnetron sputtering process can be an amorphous silicon target material, and the sputtering gas introduced can be argon gas, and the flow rate of the argon gas can be adjusted between 50sccm-200sccm. During the passivation process, the thickness of the first passivation film formed by the first magnetron sputtering process can be controlled to be between 1nm-20nm.

[0043] Step 4: forming a second passivation film on the first passivation film.

[0044] The charge density of the second passivation film 102 is 1.0*10 10 cm -2 Up to 1.0*10 14 cm -2 The second passivation film 102 can be either negatively charged or positively charged.

[0045] When the negatively charged second passivation film passivates P-type silicon, the charge it carries has a shielding effect on the minority carriers on the silicon surface, which can reduce the concentration of minority carriers on the surface and reduce surface recombination. Therefore, negative charge has a relatively good field passivation effect on P-type silicon. When the negatively charged second passivation film passivates N-type silicon, when the negative charge concentration is high, a large number of holes gather on the surface of N-type silicon, making the hole concentration in the thin layer close to the surface of the second passivation film much higher than the electron concentration, that is, a P-type inversion layer is formed. Due to the shielding effect of the fixed negative charge, the surface electron minority carrier concentration is low, the recombination rate decreases, and it can also play a field passivation effect. Similarly, the positively charged second passivation film also has a field passivation effect on N-type silicon and P-type silicon.

[0046] Setting the charge density of the second passivation film 102 within the above range can prevent the formation of positive and negative electric fields due to too low a charge density, and can also prevent the flow of carriers from being hindered by too high a charge density. In other words, the second passivation film 102 with a charge density within the above range can play a role in field passivation, and the charges carried by the second passivation film can form corresponding positive and negative electric fields, and through the action of the electric field, minority carriers are prevented from recombining on the surface of the silicon substrate, thereby improving the photoelectric conversion efficiency. In addition, the second passivation film 102 with a charge density within this range has the advantages of good insulation and light transmittance.

[0047] Optionally, the material of the second passivation film 102 may be aluminum oxide, silicon oxide, silicon nitride, hafnium oxide, gallium oxide, silicon nitride, aluminum nitride or silicon nitride, etc., and the thickness of the second passivation film 102 may be in the range of 5-50 nm. Setting the thickness range of the second passivation film within this range can, on the one hand, avoid the passivation efficiency being reduced due to the passivation film being too thin, and on the other hand, avoid the passivation film being too thick, resulting in excessively high preparation costs.

[0048] In some embodiments, a second magnetron sputtering process is performed by a magnetron sputtering device to form a second passivation film. It is worth mentioning that the magnetron sputtering device for forming the first passivation film and the magnetron sputtering device for forming the second passivation film can be the same device or different devices.

[0049] Preferably, the same magnetron sputtering device is used to realize the coordinated preparation of the first passivation film and the second passivation film, which is not only conducive to reducing hardware costs, but also can avoid the situation where the battery cell needs to be moved from the chamber of one device to the chamber of another device when different passivation film layers are prepared by different magnetron sputtering devices, causing the temperature of the cut surface of the silicon wafer to be unstable and affecting the quality of the film layer.

[0050] When the same magnetron sputtering device is used to realize the coordinated preparation of the first passivation film and the second passivation film, the target material used to form the first passivation film and the second passivation film in the magnetron sputtering device can be the same target material or different target materials. If the target materials used to form the first passivation film and the target materials used to form the second passivation film are different target materials, the magnetron sputtering device includes a first target material and a second target material isolated from each other. The cut battery cell is fixed on the moving part, and the crystalline silicon battery cell is moved by the moving part 202 so that the crystalline silicon battery cell is in the sputtering range of the first target material. The first target material is magnetron sputtered to form a first passivation film on the cut surface. After the first passivation film is formed, the crystalline silicon battery cell is moved from the sputtering range of the first target material to the sputtering range of the second target material by the moving part 202, and the second target material is magnetron sputtered to form a second passivation film on the first passivation film.

[0051] For example, Figure 2 As shown, the magnetron sputtering device includes two mutually isolated target materials, specifically target material A and target material B. The first passivation film is formed by sputtering the cut surface of target material A, and the second passivation film is formed on the first passivation film by target material B. When the first passivation film is formed, the position of the cut surface is within the sputtering range of target material A, and when the second passivation film is formed, the position of the first passivation film is within the sputtering range of target material B.

[0052] In addition, the magnetron sputtering device also includes a moving part 202, and the cut crystalline silicon cell 203 can be fixed on the moving part 202. After the first passivation film is formed, the moving part 202 can automatically move the crystalline silicon cell to the sputtering range of the target material B.

[0053] Optionally, the second magnetron sputtering process parameters include: target power of 50W to 200W, sputtering time of 5min to 20min, and air pressure environment of 0.1Pa to 10Pa. The air pressure of the magnetron sputtering vacuum chamber, the sputtering time of the target material, and the sputtering target power in the magnetron sputtering process can be adjusted within the above-defined range according to actual needs.

[0054] In some embodiments, if the second passivation film is an aluminum oxide passivation film, the target material in the second magnetron sputtering process can use an aluminum oxide target. During the coating process, the target power can be adjusted to 100w, the sputtering time can be adjusted to 10 minutes, and the gas pressure can be adjusted to 1Pa, so as to deposit an aluminum oxide passivation film with a thickness between 5nm-50nm.

[0055] In some embodiments, if the second passivation film is a silicon oxide passivation film, a silicon oxide target may be used as the target in the second magnetron sputtering process.

[0056] In some embodiments, the second magnetron sputtering process may also be a reactive magnetron sputtering process. In the process of forming the second passivation film, a reaction gas and a sputtering gas are introduced into the vacuum chamber in the magnetron sputtering device, and the flow ratio of the reaction gas and the sputtering gas is adjusted to between 1:10 and 10:1. The ions generated after the sputtering gas is ionized bombard the target material under the action of the electric field to sputter the target material, and the reaction gas is used to react with the target material sputtered from the target material to generate a passivation material, and the passivation material is deposited on the surface of the first passivation film to form a second passivation film. Among them, the reaction gas can be an oxygen source gas, nitrogen, etc., and the oxygen source gas can be oxygen, etc. Different reaction gases can be selected according to the material of the passivation film to be plated. The sputtering gas is used to generate ions that bombard the target material, which can be Ne, Ar, Kr, Xe, etc. This application does not limit the specific type of sputtering gas.

[0057] In some embodiments, if the second passivation film is silicon oxide, the target material involved in the reactive sputtering can be a silicon target material, the reaction gas is oxygen, and the sputtering gas is argon. During the coating process, oxygen and argon are introduced into the magnetron sputtering vacuum chamber, and the flow ratio of oxygen to argon is adjusted between 1:10 and 10:1, such as the flow ratio of oxygen to argon is adjusted to 7:1, the target power is adjusted to 100w, the sputtering time is adjusted to 10 minutes, and the gas pressure is adjusted to 1Pa. The argon ions generated after the argon gas is ionized bombard the silicon target material under the action of the electric field, and the oxygen and the bombarded silicon atoms generate silicon oxide, which is deposited on the surface of the first passivation film to form a second passivation film.

[0058] In some embodiments, if the second passivation film is silicon nitride, the target material involved in the reactive sputtering can be a silicon target material. During the coating process, nitrogen and argon are introduced into the magnetron sputtering vacuum, and the flow ratio of nitrogen to argon is adjusted between 1:10 and 10:1.

[0059] In some embodiments, if the second passivation film is aluminum oxide, the target material involved in the reactive sputtering may be an aluminum target material. During the coating process, oxygen and argon are introduced into the magnetron sputtering vacuum chamber, and the flow ratio of oxygen to argon is adjusted between 1:10 and 10:1.

[0060] In the present invention, the atmosphere can be adjusted according to the materials of the passivation films to be plated, such as silicon nitride, hafnium oxide, gallium oxide, silicon nitride, aluminum nitride, aluminum oxide, etc.

[0061] After the first passivation film and the second passivation film are formed, the magnetron sputtering vacuum chamber is restored to normal pressure and the crystalline silicon cell is taken out of the magnetron sputtering vacuum chamber.

[0062] The following experimental data illustrate the technical effects that the passivation structure can bring. The experimental group prepared the passivation structure by magnetron sputtering technology. In this experiment, the first passivation film is an amorphous silicon passivation film and the second passivation film is a silicon oxide passivation film. Some experimental results of the thickness of the prepared first passivation film and the second passivation film are shown in Figure 1. Figure 3 shown.

[0063] go through Figure 3 The statistics and testing of the data shown in the figure give the experimental effect data, as shown in Table 1.

[0064] Table 1

[0065]

[0066]

[0067] It can be seen from the experimental data that the prepared passivation structure can significantly improve the battery efficiency, and the coating rate is fast and the equipment cost is low.

[0068] Compared with the passivation of the cut surface by means of thermal oxygen oxidation or atomic layer deposition, the passivation film formed by magnetron sputtering has a low reaction temperature, uniform texture, low pinhole density, will not cause secondary heating annealing and reduce the battery performance, and can realize the preparation of a double-layer cooperative passivation film on the same equipment. In addition, the first passivation film is first plated on the cut surface of the battery cell in the present embodiment. The low interface defect state density between the first passivation film and the silicon substrate has achieved the purpose of chemical passivation to a certain extent. Then, the second passivation film is plated on the first passivation film. The second passivation film not only has a certain charge and can achieve a certain field passivation, but also has the advantages of good insulation and light transmittance. Moreover, plating the second passivation film on the first passivation film can ensure that the second passivation film is not oxidized. For example, the first passivation film is an amorphous silicon passivation film, and the second passivation film is silicon oxide or silicon nitride. Plating silicon oxide and silicon nitride passivation on the amorphous silicon passivation film can effectively protect the amorphous silicon from being oxidized and prevent the battery performance from being attenuated.

[0069] The embodiment of the present invention further provides a passivation structure, which is applied to the cut surface of a crystalline silicon solar cell, wherein the cut surface is the side formed by the slice, and the passivation structure comprises: a first passivation film 101 and a second passivation film 102; the first passivation film 101 is on the cut surface, and the second passivation film 102 is on the first passivation film 101; wherein the surface defect state density of the first passivation film 101 is in the range of 1.0*10 8 eV -1 cm -2 Up to 1.0*10 11 eV -1 cm -2The charge density of the second passivation film 102 is in the range of 1.0*10 10 cm -2 Up to 1.0*10 14 cm -2 The first passivation film 101 with a surface defect state density within the above range has a lower interface state defect density with the silicon substrate, thereby playing a role of chemical passivation, and the second passivation film with a charge density within the above range can play a role of field passivation, and the second passivation film 102 has good insulation and light transmittance.

[0070] In some embodiments, the thickness of the first passivation film 101 is in the range of 1 nm to 20 nm; the thickness of the second passivation film 102 is in the range of 5 nm to 50 nm. Controlling the thickness of the first passivation film 101 within this range can ensure the passivation effect of the first passivation film 101 and help avoid weakening the field passivation effect of the second passivation film 102. Controlling the thickness of the second passivation film 102 within this range can avoid the passivation efficiency being reduced due to the passivation film being too thin, and can also avoid the passivation film being too thick, resulting in excessively high preparation costs.

[0071] In some embodiments, the first passivation film 101 is an amorphous silicon passivation film; and the second passivation film 102 is a silicon oxide passivation film or an aluminum oxide passivation film.

[0072] An embodiment of the present invention further provides a solar cell, such as Figure 4 As shown, it includes: a crystalline silicon substrate; a front passivation film layer and a front electrode are arranged on the front of the crystalline silicon substrate; a back passivation film layer and a back electrode are arranged on the back of the crystalline silicon substrate; and a passivation structure is arranged on at least one side of the crystalline silicon substrate as a cutting surface. The passivation structure in this embodiment includes: a first passivation film 101 and a second passivation film 102, the first passivation film is located between the cutting surface and the second passivation film; wherein the surface defect state density of the first passivation film is in the range of 1.0*10 8 eV -1 cm -2 Up to 1.0*10 11 eV -1 cm -2 The charge density of the second passivation film is in the range of 1.0*10 10 cm -2 Up to 1.0*10 14 cm -2 between.

[0073] In some embodiments, the thickness of the first passivation film is in the range of 1 nm to 20 nm; the thickness of the second passivation film is in the range of 5 nm to 50 nm.

[0074] In some embodiments, the first passivation film is an amorphous silicon passivation film; and the second passivation film is a silicon oxide passivation film or a silicon nitride passivation film.

[0075] Those skilled in the art will appreciate that the above embodiments are specific examples of the present invention, and in practical applications, various changes may be made to the embodiments in form and detail without departing from the spirit and scope of the present invention. Any person skilled in the art may make changes and modifications without departing from the spirit and scope of the present invention, and therefore the scope of protection of the present invention shall be subject to the scope defined in the claims.

Claims

1. A method for preparing a passivation structure for a battery cut surface, characterized in that: include: Providing a crystalline silicon cell sheet, wherein the crystalline silicon cell sheet has a cutting surface, and the cutting surface is a side surface formed by slicing; The surface temperature of the cutting surface is controlled within a range of 25°C to 400°C; forming a first passivation film on the cut surface; forming a second passivation film on the first passivation film; The surface defect state density of the first passivation film is in the range of 1.0*10 8 eV -1 cm -2 Up to 1.0*10 11 eV -1 cm -2 The charge density of the second passivation film is in the range of 1.0*10 10 cm -2 Up to 1.0*10 14 cm -2 between.

2. The preparation method according to claim 1, characterized in that: The process steps of forming the first passivation film and the second passivation film include: The first passivation film and the second passivation film are formed by using the same magnetron sputtering device.

3. The preparation method according to claim 2, characterized in that: The magnetron sputtering device comprises: a first target material and a second target material isolated from each other; A moving component, used for fixing the crystalline silicon cell; Moving the crystalline silicon cell piece by the moving component so that the crystalline silicon cell piece is within the sputtering range of the first target material; Performing magnetron sputtering on the first target material to form the first passivation film on the cut surface; Moving the crystalline silicon cell piece by the moving component so that the crystalline silicon cell piece is within the sputtering range of the second target material; The second target is subjected to magnetron sputtering to form the second passivation film on the first passivation film.

4. The preparation method according to claim 1, characterized in that: The first passivation film is an amorphous silicon passivation film; the second passivation film is a silicon oxide passivation film or an aluminum oxide passivation film.

5. The preparation method according to claim 4, characterized in that: The thickness of the first passivation film is in the range of 1 nm to 20 nm; the thickness of the second passivation film is in the range of 5 nm to 50 nm.

6. The preparation method according to claim 1, characterized in that: The process steps of forming the first passivation film and the second passivation film include: A first magnetron sputtering process is performed by a magnetron sputtering device to form a first passivation film, wherein the first magnetron sputtering process parameters include: the target material is an amorphous silicon target material, the target power is 50W to 200W, the sputtering gas is argon, the flow rate of the argon gas is 50sccm to 200sccm, the sputtering time is 5min to 20min, and the gas pressure environment is 0.1Pa to 10Pa; A second magnetron sputtering process is performed by a magnetron sputtering device to form a second passivation film, wherein the second magnetron sputtering process parameters include: the target material is a silicon target material or an aluminum target material, the target power is 50W to 200W, the sputtering gas is argon, the reaction gas is oxygen, the flow ratio of oxygen to argon is adjusted between 1:10 and 10:1, the sputtering time is 5min to 20min, and the air pressure environment is 0.1Pa to 10Pa.

7. The preparation method according to claim 1, characterized in that: The process steps of forming the first passivation film and the second passivation film include: A first magnetron sputtering process is performed by a magnetron sputtering device to form a first passivation film, wherein the first magnetron sputtering process parameters include: the target material is an amorphous silicon target material, the target power is 50W to 200W, the sputtering gas is argon, the flow rate of argon is 50 to 200sccm, the sputtering time is 5min to 20min, and the air pressure environment is 0.1Pa to 10Pa; A second magnetron sputtering process is performed by a magnetron sputtering device to form a second passivation film, wherein the second magnetron sputtering process parameters include: the target material is an aluminum oxide target material or a silicon oxide target material, the sputtering gas is argon, the argon flow rate is 50 to 200 sccm, the target power is 50 W to 200 W, the sputtering time is 5 min to 20 min, and the air pressure environment is 0.1 Pa to 10 Pa.

8. The preparation method according to any one of claims 1 to 7, characterized in that Before forming the first passivation film on the cutting surface, the method comprises: The surfaces of the crystalline silicon cell except the cut surface are wrapped to expose the cut surface.

9. A passivation structure, characterized in that: Applied to the cutting surface of a crystalline silicon cell, the cutting surface is the side surface formed by slicing, and the passivation structure includes: a first passivation film and a second passivation film, wherein the first passivation film is located between the cut surface and the second passivation film; The surface defect state density of the first passivation film is in the range of 1.0*10 8 eV -1 cm -2 Up to 1.0*10 11 eV -1 cm -2 The charge density of the second passivation film is in the range of 1.0*10 10 cm -2 Up to 1.0*10 14 cm -2 between.

10. The passivation structure according to claim 9, characterized in that: The first passivation film is an amorphous silicon passivation film; the second passivation film is a silicon oxide passivation film or an aluminum oxide passivation film.

11. The passivation structure according to claim 10, characterized in that: The thickness of the first passivation film is in the range of 1 nm to 20 nm; the thickness of the second passivation film is in the range of 5 nm to 50 nm.

12. A solar cell, characterized in that: The solar cell comprises: Crystalline silicon substrate; A front passivation film layer and a front electrode are arranged on the front side of the crystalline silicon substrate; A back passivation film layer and a back electrode are arranged on the back side of the crystalline silicon substrate; A passivation structure according to any one of claims 9 to 11 is arranged on at least one side surface of the crystalline silicon substrate serving as a cutting surface.

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