Solar cell preparation method and TOPCon solar cell
During the preparation of TOPCon solar cells, borosilicate glass on the side of the silicon wafer is removed by using water bleaching and submerged pickling methods, which solves the edge leakage problem and improves the reliability of the battery and the PN junction control accuracy.
Patent Information
- Application Number
- CN202411581366.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-07
- Publication Date
- 2025-02-21
AI Technical Summary
During the preparation of TOPCon solar cells, it is difficult for the prior art to completely remove the borosilicate glass on the side of the battery while retaining the front borosilicate glass, resulting in edge leakage and affecting the yield of the finished product.
A solar cell preparation method is adopted, including rinsing and submerging the silicon wafer, removing borosilicate glass on the back and sides, while retaining the partial thickness of borosilicate glass on the front. Through this method, there is no residual BSG on the side of the silicon wafer, which reduces edge leakage and more accurately controls the depth and doping concentration of the PN junction during subsequent phosphorus diffusion.
It effectively reduces leakage at the edge of the battery, improves the long-term reliability of the battery, and realizes more accurate PN junction control, improving the performance of the battery.
Smart Images
Figure CN119497438A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of solar cells, and in particular to a method for preparing a solar cell and a TOPCon solar cell. Background Art
[0002] At present, in the process of preparing TOPCon (tunneling oxide passivation contact) cells, boron diffusion is a key step in preparing PN junctions. Through high-temperature boron diffusion treatment, a boron diffusion layer is formed on the surface of the silicon wafer. However, boron atoms will react with the surface of the silicon wafer to form borosilicate glass (BSG). Since we only need the PN junction on the front side, the borosilicate glass and boron diffusion layer on the back and sides need to be removed, but the borosilicate glass on the front side needs to be retained to reduce the impact of subsequent phosphorus diffusion treatment on the front boron diffusion layer.
[0003] Since the paste on the front of the TOPCon cell is silver-aluminum paste, the thickness of the boron diffusion layer on the front needs to reach 0.5um to meet the contact requirements, so the thickness of the BSG on the front, side and back of the cell is more than 50nm. Since the BSG on the side of the cell is thicker, the current process technology cannot completely remove the BSG on the side while retaining the BSG on the front. There is BSG residue on the edge of the side of the silicon wafer, which causes edge leakage and affects the yield of the finished product. Summary of the invention
[0004] The present application provides a solar cell preparation method and a TOPCon solar cell to solve or alleviate the technical problems mentioned above. The silicon wafer prepared by the solar cell preparation method of the technical solution of the present application can not only reduce the leakage phenomenon at the edge of the battery and improve the long-term reliability of the battery; but also can more accurately control the depth and doping concentration of the PN junction.
[0005] In a first aspect, an embodiment of the present application provides a method for preparing a solar cell, comprising: Providing a silicon wafer, wherein a surface of the silicon wafer has borosilicate glass of a first thickness; The silicon wafer is sequentially subjected to water rinsing and immersion pickling to completely remove the borosilicate glass on the back and sides of the silicon wafer, and to retain a second thickness of borosilicate glass on the front of the silicon wafer; wherein the first thickness is greater than the second thickness; The silicon wafer that has been immersion-picked is etched with alkaline solution to remove the boron diffusion layer on the back side and the side surface of the silicon wafer.
[0006] Optionally, the silicon wafer is subjected to water rinsing and pickling, comprising: The silicon wafer is placed in a first pickling solution by floating on water to remove the borosilicate glass on the back of the silicon wafer and part of the borosilicate glass on the side of the silicon wafer, and retain the borosilicate glass on the front of the silicon wafer.
[0007] Optionally, during the water pickling, the interface between the silicon wafer and the boron diffusion layer is higher than the liquid surface of the first pickling solution, and the distance between the interface and the liquid surface is 1-3 μm.
[0008] Optionally, the silicon wafers that have been subjected to water pickling are subjected to immersion pickling, including: The silicon wafer that has been rinsed and pickled in water is immersed in a second pickling solution to remove the borosilicate glass remaining on the side of the silicon wafer.
[0009] Optionally, in the water rinsing and pickling process, the first pickling liquid is a hydrofluoric acid solution with a mass concentration of 25-35%.
[0010] Optionally, during the water rinsing and pickling process, the pickling time is 5-25 minutes.
[0011] Optionally, during the immersion pickling process, the second pickling liquid is a hydrofluoric acid solution with a mass concentration of 0.5-2%.
[0012] Optionally, during the immersion pickling process, the pickling time is 20-40 seconds.
[0013] Optionally, in the alkaline solution etching, the alkaline solution used includes one or more of KOH solution, NaOH solution, and TMAH solution, and the etching time is 3-6 minutes.
[0014] In a second aspect, an embodiment of the present application provides a TOPCon solar cell, which is formed by using the solar cell preparation method provided by any of the above embodiments.
[0015] The above technical solution adopted in the embodiment of the present application may have the following advantages: In the solar cell preparation method of the present application, the silicon wafer with borosilicate glass on the surface is firstly subjected to water rinsing and pickling, so that the borosilicate glass on the back and sides of the silicon wafer is corroded, while the borosilicate glass (BSG) on the front is prevented from being corroded. However, the water rinsing and pickling will cause BSG to remain on the side of the silicon wafer (especially on the upper edge of the side), and the thickness of the BSG remaining on the side is less than the first thickness; then, the silicon wafer that has been subjected to water rinsing and pickling is subjected to immersion pickling to completely remove the BSG remaining on the side of the silicon wafer, while retaining a portion of the thickness of the BSG on the front of the silicon wafer (after immersion pickling, the thickness of the BSG on the front of the silicon wafer is reduced from the first thickness to the second thickness). The silicon wafer prepared by the solar cell preparation method of the present application can reduce the leakage phenomenon at the edge of the battery and improve the long-term reliability of the battery because there is no BSG remaining on the side; moreover, since the silicon wafer retains BSG on the front, the diffusion rate of phosphorus atoms into the silicon wafer can be slowed down in the subsequent phosphorus diffusion process, thereby more accurately controlling the depth and doping concentration of the PN junction. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application.
[0017] Figure 1 is a flow chart of a method for preparing a solar cell according to an embodiment of the present application; Figure 2 It is a schematic diagram of water rinsing and pickling of silicon wafers in an embodiment of the present application.
[0018] Reference numerals 1. Silicon wafer; 2. Pickling tank; 3. Roller; 4. First pickling solution. DETAILED DESCRIPTION
[0019] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and should not be understood as limiting the present application. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other in the absence of conflict.
[0020] like Figure 1 As shown, the embodiment of the present application provides a method for preparing a solar cell, comprising: Step S110: providing a silicon wafer, wherein a surface of the silicon wafer has borosilicate glass of a first thickness.
[0021] The silicon wafer in step S110 may be an N-type silicon wafer, and the silicon wafer is subjected to boron diffusion treatment to form a boron diffusion layer on the surface of the silicon wafer, and borosilicate glass is formed on the surface of the boron diffusion layer. The surface of the silicon wafer includes a front side of the silicon wafer and a back side of the silicon wafer that are arranged opposite to each other, and also includes a side surface of the silicon wafer connecting the front side of the silicon wafer and the back side of the silicon wafer.
[0022] Step S120: performing water rinsing and immersion pickling on the silicon wafer in sequence to completely remove the borosilicate glass on the back and sides of the silicon wafer, and leaving a second thickness of borosilicate glass on the front of the silicon wafer; wherein the first thickness is greater than the second thickness.
[0023] In step S120, the silicon wafer is subjected to water rinsing and pickling, which may include: Step S121: placing the silicon wafer in a first pickling solution by floating on water to remove the borosilicate glass on the back of the silicon wafer and part of the borosilicate glass on the side of the silicon wafer, and retaining the first thickness of borosilicate glass on the front of the silicon wafer.
[0024] During the water pickling process, the silicon wafer is transported in the chain cleaning machine through a chain roller conveyor, and before the silicon wafer enters the pickling tank, a layer of water film is formed on the front of the silicon wafer using a spray system to protect the BSG on the front from being corroded by the first pickling liquid; then the silicon wafer is transported to the pickling tank. Figure 2 As shown, after the silicon wafer 1 enters the pickling tank 2, the silicon wafer 1 is placed on the roller 3. Although the static liquid level of the first pickling liquid 4 does not exceed the height of the roller 3, the silicon wafer 1 is relatively thin and the first pickling liquid 4 will turn up with the rotation of the roller 3, so that the first pickling liquid 4 is close to the silicon wafer 1. The silicon wafer 1 is like floating on the first pickling liquid 4, so that the first pickling liquid 4 contacts the back and side of the silicon wafer 1, corroding the BSG on the back and side of the silicon wafer 1. Since the BSG on the side of the silicon wafer (especially the upper edge of the side) will intermittently contact with the first pickling liquid, the BSG on the side of the silicon wafer will remain, but the thickness of the BSG remaining on the side of the silicon wafer (the third thickness) is less than the thickness of the BSG on the front of the silicon wafer (the first thickness).
[0025] In step S120, immersion pickling is performed on the silicon wafer that has been subjected to water rinsing and pickling, which may include: Step S121: immersing the silicon wafer that has been rinsed and pickled in water in a second pickling solution to remove the borosilicate glass remaining on the side of the silicon wafer.
[0026] During the immersion pickling process, the silicon wafer that has been rinsed with water is immersed in the second pickling solution, so that the front, back and sides of the silicon wafer are in contact with the second pickling solution, so that the BSG remaining on the side of the silicon wafer (especially the upper edge of the side) and the BSG on the front of the silicon wafer are corroded by the second pickling solution. The BSG remaining on the side of the silicon wafer is removed by the corrosion of the second pickling solution. Since the thickness of the BSG remaining on the side of the silicon wafer (the third thickness) is less than the first thickness, when the BSG on the side of the silicon wafer is completely removed, some thickness of BSG still exists on the front of the silicon wafer, but the thickness of the BSG on the front of the silicon wafer is reduced from the first thickness to the second thickness.
[0027] It should be noted that due to the particularity of the pickling process, in any embodiment of the present application, the BSG remaining on the side of the silicon wafer after the silicon wafer is pickled by water is not evenly distributed on the side of the silicon wafer, but is distributed in a trapezoidal shape, that is, the closer to the front of the silicon wafer, the greater the BSG thickness, and the farther away from the front of the silicon wafer, the smaller the BSG thickness, until it is 0. Therefore, the "third thickness" refers to the BSG thickness at the upper edge of the side of the silicon wafer.
[0028] In some embodiments, the first thickness may be 70-100 nm, for example, 70 nm, 80 nm, 90 nm, or 100 nm. In some embodiments, the second thickness may be 50-80 nm, for example, 50 nm, 60 nm, 70 nm, or 80 nm, and the third thickness may be 1-20 nm, for example, 1 nm, 5 nm, 10 nm, or 20 nm.
[0029] Step S130: performing alkaline etching on the silicon wafer that has been immersion-picked to remove the boron diffusion layer on the back and side surfaces of the silicon wafer.
[0030] In step S130, the silicon wafer that has been immersed in acid is placed in an alkaline solution. Since the borosilicate glass on the back and sides of the silicon wafer has been removed, the boron diffusion layer is exposed. The alkaline solution is used to etch away the boron diffusion layer on the back and sides of the silicon wafer, thereby reducing the risk of edge leakage.
[0031] In the solar cell preparation method of the present application, the silicon wafer with borosilicate glass on the surface is firstly subjected to water rinsing and pickling, so that the borosilicate glass on the back and sides of the silicon wafer is corroded, while the borosilicate glass (BSG) on the front is prevented from being corroded. However, the water rinsing and pickling will cause BSG to remain on the side of the silicon wafer (especially on the upper edge of the side), and the thickness of the BSG remaining on the side is less than the first thickness; then, the silicon wafer that has been subjected to water rinsing and pickling is subjected to immersion pickling to completely remove the BSG remaining on the side of the silicon wafer, while retaining a portion of the thickness of the BSG on the front of the silicon wafer (after immersion pickling, the thickness of the BSG on the front of the silicon wafer is reduced from the first thickness to the second thickness). The silicon wafer prepared by the solar cell preparation method of the present application can reduce the leakage phenomenon at the edge of the battery and improve the long-term reliability of the battery because there is no BSG remaining on the side; moreover, since the silicon wafer retains BSG on the front, the diffusion rate of phosphorus atoms into the silicon wafer can be slowed down in the subsequent phosphorus diffusion process, thereby more accurately controlling the depth and doping concentration of the PN junction.
[0032] In some embodiments, during the water pickling in step S120, the interface between the silicon wafer and the boron diffusion layer is higher than the liquid surface of the first pickling solution, and the distance between the interface and the liquid surface is 1-3 μm. It should be noted that the liquid surface of the first pickling solution at this time refers to the liquid surface that the first pickling solution can reach after being turned up by the roller, rather than the static liquid surface of the first pickling solution.
[0033] During the water pickling, if the interface between the silicon wafer and the boron diffusion layer is not higher than the liquid level of the first pickling solution, or the distance between the interface and the liquid level is too small, the first pickling solution is easy to gradually turn over from the side of the silicon wafer to the upper surface of the silicon wafer, corroding the borosilicate glass and PN junction on the upper surface. Etching marks will appear on the corroded silicon wafer, which will not only reduce the area of the effective PN junction on the front of the silicon wafer, but also reduce the battery yield. If the distance between the interface and the liquid level is too large, the BSG on the side of the silicon wafer cannot be corroded by the first pickling solution, and the thickness of the BSG remaining on the upper edge of the side of the silicon wafer may be equal to the thickness of the BSG on the front of the silicon wafer, which is not conducive to the subsequent complete removal of the BSG on the side of the silicon wafer. When the distance between the interface and the liquid level is 1-3μm, not only can the first pickling solution be avoided from corroding the upper surface of the silicon wafer, but also the BSG on the side of the silicon wafer can be corroded by the first pickling solution, so that the thickness of the BSG on the upper edge of the side of the silicon wafer is less than the thickness of the BSG on the front of the silicon wafer.
[0034] In some embodiments, during the water rinsing and pickling process in step S120, the first pickling liquid is a hydrofluoric acid solution with a mass concentration of 25-35%.
[0035] Hydrofluoric acid solution can effectively remove BSG on silicon wafers and has a certain flattening effect on the surface of silicon wafers. In the process of water rinsing and pickling, a hydrofluoric acid solution with a mass concentration of 25-35% is used. The mass concentration of the hydrofluoric acid solution is moderate, which can quickly and effectively remove BSG while avoiding excessive corrosion of silicon wafers. Specifically, in the process of water rinsing and pickling, the mass concentration of the hydrofluoric acid solution can be 25%, 28%, 30%, 32% or 35%.
[0036] In some embodiments, during the water pickling process, the pickling time is 5-25 minutes, which can ensure that the BSG on the back and sides of the silicon wafer is removed. Specifically, during the water pickling process, the pickling time can be 5 minutes, 10 minutes, 15 minutes, 20 minutes or 25 minutes.
[0037] In some embodiments, during the immersion pickling process, the second pickling liquid is a hydrofluoric acid solution with a mass concentration of 0.5-2%.
[0038] During the immersion pickling process, if a hydrofluoric acid solution with a high mass concentration is used, the BSG on the front of the silicon wafer will be severely corroded and the PN junction may be damaged; if a hydrofluoric acid solution with an extremely low concentration is used, it may be difficult to remove the BSG on the side of the silicon wafer; therefore, a hydrofluoric acid solution with a slightly lower mass concentration (i.e., a mass concentration of 0.5-2%) is used. At this time, not only can the BSG remaining on the side of the silicon wafer be removed, but also excessive corrosion of the BSG on the front of the silicon wafer can be avoided. Specifically, during the immersion pickling process, the mass concentration of the hydrofluoric acid solution can be 0.5%, 1%, 1.5% or 2%.
[0039] In some embodiments, during the immersion pickling process, the pickling time is 20-40 seconds. The pickling time within this range can not only remove the BSG remaining on the side of the silicon wafer, but also retain the BSG of the thickness of the front side of the silicon wafer. Specifically, during the immersion pickling process, the pickling time can be 20 seconds, 25 seconds, 30 seconds, 35 seconds or 40 seconds.
[0040] In some embodiments, in the alkaline solution etching, the alkaline solution used includes one or more of KOH solution, NaOH solution, and tetramethylammonium hydroxide (TMAH) solution, and the etching time is 3-6 minutes.
[0041] In the alkaline solution etching process, the silicon wafer is etched with one or more of KOH solution, NaOH solution, and TMAH solution, so that the velvet surface on the back of the silicon wafer can be etched into a polished surface, and the boron diffusion layer on the back and side of the silicon wafer can be removed, thereby reducing the contact area between the metal electrode and the silicon wafer and reducing metal-induced carrier recombination. When the etching time in the alkaline solution etching is 3-6 minutes (for example, 3 minutes, 4 minutes, 5 minutes or 6 minutes), the boron diffusion layer on the back and side of the silicon wafer can be effectively removed.
[0042] An embodiment of the present application provides a TOPCon solar cell, which is formed by using the solar cell preparation method provided by any of the above embodiments.
[0043] In some embodiments, a TOPCon solar cell comprises: A silicon wafer, the silicon wafer comprising a front side and a back side arranged opposite to each other, and the silicon wafer is an N-type silicon wafer; The front side of the silicon wafer includes a boron diffusion layer, a front passivation layer, and a front electrode stacked in sequence; wherein the boron diffusion layer is close to the silicon wafer, the front electrode is far away from the silicon wafer, and the front electrode penetrates the front passivation layer and contacts the boron diffusion layer.
[0044] It is on the back side of the silicon wafer and includes a tunneling oxide layer, an N-type polysilicon doping layer, a back passivation layer, and a back electrode stacked in sequence; wherein the tunneling oxide layer is close to the silicon wafer, the back electrode is far away from the silicon wafer, and the back electrode penetrates the back passivation layer and contacts with the N-type polysilicon doping layer.
[0045] In some embodiments, a method for preparing a TOPCon solar cell comprises: Step S201: providing a silicon wafer, wherein the silicon wafer comprises a front side and a back side which are arranged opposite to each other, and the silicon wafer is an N-type silicon wafer; Step S202: performing boron diffusion treatment on the silicon wafer to form a boron diffusion layer and BSG stacked from the inside to the outside on the surface of the silicon wafer; Step S203: using the solar cell preparation method provided by any of the above embodiments of the present application, etching the silicon wafer after the boron diffusion treatment to remove the boron diffusion layer and BSG on the back and side of the silicon wafer, and only retaining the boron diffusion layer and BSG on the front of the silicon wafer; Step S204: using a plasma enhanced chemical vapor deposition (PECVD) method to form a tunneling oxide layer on the back side of the silicon wafer; Step S205: performing phosphorus diffusion treatment on the silicon wafer with the tunnel oxide layer formed thereon to form an N-type polysilicon doping layer on the surface of the silicon wafer; Step S206: removing the N-type polysilicon doping layer on the front and side surfaces of the silicon wafer, and only retaining the N-type polysilicon doping layer on the back surface of the silicon wafer (i.e., the surface of the tunneling oxide layer); Step S207: removing BSG on the front side of the silicon wafer; Step S208: forming a front passivation layer on the boron diffusion layer; forming a back passivation layer on the N-type polysilicon doped layer; Step S209: forming a front electrode on the front side of the silicon wafer, the front electrode penetrating the front passivation layer and contacting the boron diffusion layer; On the back side of the silicon wafer, a back side electrode is formed which penetrates the back side passivation layer and contacts the N-type polysilicon doping layer.
[0046] The following specific examples further illustrate the present application, but should not be construed as limiting the present application. Without departing from the spirit and substance of the present application, modifications or replacements made to the methods, steps or conditions of the present application are within the scope of the present application.
[0047] [Example 1] The method for preparing a solar cell provided in Example 1 comprises: Step S110a: providing a silicon wafer, wherein the surface of the silicon wafer has borosilicate glass with a first thickness H1 of 80 nm; Step S121a: placing the silicon wafer in a hydrofluoric acid solution with a mass concentration C1 of 30% by a water-floating method, and the pickling time t1 is 10 minutes, so that the interface between the silicon wafer and the boron diffusion layer is 2 μm higher than the liquid level of the first pickling solution, so as to remove the borosilicate glass on the back of the silicon wafer and part of the borosilicate glass on the side of the silicon wafer, leaving borosilicate glass with a third thickness H3 of 10 nm on the side of the silicon wafer, and retaining 80 nm of borosilicate glass on the front of the silicon wafer; Step S122a: immersing the silicon wafer that has been rinsed and pickled in a hydrofluoric acid solution with a mass concentration C2 of 0.5% for a pickling time t2 of 30 seconds to remove the borosilicate glass remaining on the side of the silicon wafer and to leave the borosilicate glass with a second thickness H2 of 70 nm on the front of the silicon wafer; Step S130a: placing the immersion pickled silicon wafer in a NaOH solution for etching, with the etching time t3 being 5 minutes, so as to remove the boron diffusion layer on the back and side surfaces of the silicon wafer.
[0048] [Example 2] - [Example 6] The solar cell preparation method of Example 2 to Example 6 is similar to the solar cell preparation method of Example 1, and the only difference lies in the specific parameters in the solar cell preparation method. The specific parameters in the solar cell preparation method of Example 2 to Example 6 are shown in Table 1.
[0049] Table 1
[0050] In order to more clearly illustrate the technical effects of the embodiments of the present application, the present application also points out the solar cell preparation method of Comparative Example 1.
[0051] [Comparative Example 1] The method for preparing a solar cell provided in Comparative Example 1 comprises: Step S110b: providing a silicon wafer, wherein a surface of the silicon wafer has borosilicate glass of a first thickness; Step S120b: placing the silicon wafer in a hydrofluoric acid solution with a mass concentration C1 of 30% by a water-floating method, and the pickling time t1 is 10 minutes, so that the interface between the silicon wafer and the boron diffusion layer is higher than the liquid surface of the first pickling solution; Step S130b: placing the silicon wafer that has been rinsed and pickled in water in a NaOH solution for etching, with the etching time t3 being 5 minutes, so as to remove the boron diffusion layer on the back and side surfaces of the silicon wafer.
[0052]
Performance test
[0053] Table 2
[0054] In the present application, the solar cell preparation method of comparative example 1 can only remove the borosilicate glass on the back of the silicon wafer and part of the borosilicate glass on the side of the silicon wafer through step S120b, and retain the first thickness of borosilicate glass on the front of the silicon wafer; but the third thickness of borosilicate glass still remains on the side of the silicon wafer, and the first thickness is greater than the third thickness. The solar cell preparation method in Examples 1-6 of the present application can completely remove the borosilicate glass on the back and side of the silicon wafer by sequentially performing water rinsing and immersion pickling, and retain the borosilicate glass of part of the thickness on the front of the silicon wafer. According to the data in Table 2, compared with Comparative Example 1, the TOPCon solar cell formed by the solar cell preparation method of Examples 1-6 of the present application has improved short-circuit current density Jsc, fill factor FF and photoelectric conversion efficiency PCE. This shows that the TOPCon solar cell prepared by the solar cell preparation method of Examples 1-6 of the present application can reduce the leakage phenomenon at the edge of the battery and improve the long-term reliability of the battery; moreover, the depth and doping concentration of the PN junction can be more accurately controlled.
[0055] In summary, in the solar cell preparation method of the present application, the silicon wafer with borosilicate glass on the surface is firstly subjected to water rinsing and pickling, so that the borosilicate glass on the back and sides of the silicon wafer is corroded, while the borosilicate glass (BSG) on the front is prevented from being corroded. However, the water rinsing and pickling will cause BSG to remain on the side of the silicon wafer (especially on the upper edge of the side), and the thickness of the BSG remaining on the side is less than the first thickness; then, the silicon wafer that has been subjected to water rinsing and pickling is subjected to immersion pickling to completely remove the BSG remaining on the side of the silicon wafer, while retaining a portion of the thickness of the BSG on the front of the silicon wafer (after immersion pickling, the thickness of the BSG on the front of the silicon wafer is reduced from the first thickness to the second thickness). The silicon wafer prepared by the solar cell preparation method of the present application can reduce the leakage phenomenon at the edge of the battery and improve the long-term reliability of the battery because there is no BSG remaining on the side; moreover, since the silicon wafer retains BSG on the front, the diffusion rate of phosphorus atoms into the silicon wafer can be slowed down in the subsequent phosphorus diffusion process, thereby more accurately controlling the depth and doping concentration of the PN junction.
[0056] An embodiment of the present application provides a photovoltaic module (not shown), including at least one battery string, the battery string includes at least two perovskite solar cells of any embodiment, and adjacent perovskite solar cells can be connected together by series welding.
[0057] The embodiment of the present application can provide a photovoltaic system, including the photovoltaic components in the above embodiment. The advantages of the above photovoltaic components are also possessed by the photovoltaic system, which will not be repeated here. The above photovoltaic system has a wide range of applications, not only limited to photovoltaic power stations, such as ground power stations, rooftop power stations and water power stations, but also includes various equipment and devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars and solar buildings. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is to say, the photovoltaic system can be used in all fields where solar energy is required for power generation. Taking the photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple photovoltaic components. For example, multiple photovoltaic components can form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter and is converted into the alternating current required by the mains power grid and then connected to the mains network to realize solar power supply.
[0058] It should be noted that the terms "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "front", "back", etc. are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. The orientation words "inside" and "outside" refer to the inside and outside relative to the outline of each component itself. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Therefore, the exemplary term "above..." can include both "above..." and "below..." orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used here are interpreted accordingly.
[0059] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.
[0060] It should also be noted that "one embodiment", "another embodiment", "embodiment", etc. mentioned in this application refer to the specific features, structures or characteristics described in conjunction with the embodiment included in at least one embodiment generally described in this application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Further, when describing a specific feature, structure or characteristic in conjunction with any embodiment, it is claimed that the realization of such feature, structure or characteristic in conjunction with other embodiments also falls within the scope of this application.
[0061] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.
[0062] It should also be noted that the above are only preferred embodiments of the present application, and the patent protection scope of the present application is not limited thereto. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.
Claims
1. A method for preparing a solar cell, characterized in that: include: Providing a silicon wafer, wherein a surface of the silicon wafer has borosilicate glass of a first thickness; The silicon wafer is sequentially subjected to water rinsing and immersion pickling to completely remove the borosilicate glass on the back and sides of the silicon wafer, and to retain a second thickness of borosilicate glass on the front of the silicon wafer; wherein the first thickness is greater than the second thickness; The silicon wafer that has been immersion-picked is etched with alkaline solution to remove the boron diffusion layer on the back side and the side surface of the silicon wafer.
2. The method for preparing a solar cell according to claim 1, characterized in that: The silicon wafer is subjected to water rinsing and pickling, comprising: The silicon wafer is placed in a first pickling solution by floating on water to remove the borosilicate glass on the back of the silicon wafer and part of the borosilicate glass on the side of the silicon wafer, and retain the borosilicate glass on the front of the silicon wafer.
3. The method for preparing a solar cell according to claim 2, characterized in that: When performing water pickling, the interface between the silicon wafer and the boron diffusion layer is higher than the liquid surface of the first pickling solution, and the distance between the interface and the liquid surface is 1-3 μm.
4. The method for preparing a solar cell according to claim 2, characterized in that: Immerse and pickle the silicon wafers that have been pickled by water, including: The silicon wafer that has been rinsed and pickled in water is immersed in a second pickling solution to remove the borosilicate glass remaining on the side of the silicon wafer.
5. The method for preparing a solar cell according to claim 2, characterized in that: In the above-water pickling process, the first pickling liquid is a hydrofluoric acid solution with a mass concentration of 25-35%.
6. The method for preparing a solar cell according to any one of claims 1 to 4, characterized in that: In the water rinsing and pickling process, the pickling time is 5-25 minutes.
7. The method for preparing a solar cell according to claim 4, characterized in that: In the immersion pickling process, the second pickling liquid is a hydrofluoric acid solution with a mass concentration of 0.5-2%.
8. The method for preparing a solar cell according to any one of claims 1 to 4, characterized in that: In the immersion pickling process, the pickling time is 20-40 seconds.
9. The method for preparing a solar cell according to any one of claims 1 to 4, characterized in that: In the alkaline solution etching, the alkaline solution includes one or more of KOH solution, NaOH solution, and TMAH solution, and the etching time is 3-6 minutes.
10. A TOPCon solar cell, characterized in that: The solar cell is formed by the method for preparing the solar cell according to any one of claims 1 to 9.