Solar cell, method for manufacturing solar cell, stacked cell, and photovoltaic module

Abstract

This application relates to the field of solar cell technology, and more particularly to a solar cell, a method for fabricating a solar cell, a tandem solar cell, and a photovoltaic module. The solar cell includes a substrate, which includes a first surface and a second surface disposed opposite to each other. The substrate also includes a third surface connecting the first and second surfaces. The first surface includes a first region close to the third surface and a second region far from the third surface. The distance between the first region and the second surface is less than the distance between the second region and the second surface. The connection point between the first and second regions is an inclined plane. The first region includes a first textured structure, and the third surface includes a second textured structure. In this application, the first region is formed by first performing localization processing at a cutting position on the first surface, making the first region closer to the substrate. Subsequently, the first region and the third surface are etched to remove PN junction damage areas and microcracks in the first region and the third surface, reducing the recombination rate and increasing the open-circuit voltage and circuit current, thereby improving the conversion efficiency of the solar cell.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to a solar cell, a method for preparing a solar cell, a tandem cell, and a photovoltaic module. Background Technology

[0002] A solar cell (also known as a photovoltaic cell) is a thin film of photoelectric semiconductors that generates electricity directly using sunlight. When sunlight shines on the surface of a solar cell, photons are absorbed and electrons are excited to form an electric current, thus generating electrical energy.

[0003] After multi-segmented batteries are segmented using lasers, microcracks exist on the fracture surface, introducing a large number of recombination centers. At the same time, there are PN junction damage areas at the edge of the fracture surface, which can lead to edge leakage. Summary of the Invention

[0004] This application provides a solar cell, a method for preparing a solar cell, a tandem cell, and a photovoltaic module, which removes the PN junction damage area and microcracks formed by laser slicing, reduces the recombination rate, and increases the open-circuit voltage and circuit current, thereby improving the conversion efficiency of the solar cell.

[0005] This application provides a solar cell in a first aspect. The solar cell includes a substrate, the substrate includes a first surface and a second surface disposed opposite to each other, and the substrate further includes a third surface connecting the first surface and the second surface. The first surface includes a first region close to the third surface and a second region far from the third surface. The distance between the first region and the second surface is less than the distance between the second region and the second surface. The connection between the first region and the second region has an inclined angle. The doping concentration in the second region is greater than that in the first region; The first region includes a first texture structure, and the third surface includes a second texture structure, wherein the reflectivity of the first texture structure is less than or equal to the reflectivity of the second texture structure.

[0006] In one possible design, the tilt angle is 50°-120°.

[0007] In one possible design, the distance between the first region and the second surface is D1, the distance between the second region and the second surface is D2, and the difference between D2 and D1 is 1μm-5μm.

[0008] In one possible design, the width of the first region is 50μm-500μm.

[0009] In one possible design, the first texture structure is a first pyramid structure with a height of 1μm-2μm.

[0010] In one possible design, the second zone is provided with a third pyramid structure, the height of which is 0.8μm-2μm.

[0011] In one possible design, the reflectivity of the first pyramid structure is 2%-3% lower than that of the third pyramid structure.

[0012] In one possible design, the first texture structure is a first base structure, and the side length of the first base structure is 3μm-30μm.

[0013] In one possible design, the second texture structure is a second pyramid structure with a height of 0.5μm-2μm.

[0014] In one possible design, the second texture structure is a second base structure with a side length of 3μm-30μm.

[0015] This application provides a second aspect of a method for preparing a solar cell, wherein the solar cell includes a substrate, and the substrate includes a first surface and a second surface; A first laser is used to create a groove on the first surface of the substrate, forming a first region and a second region on the first surface. The distance between the first region and the second surface of the substrate is less than the distance between the second region and the second surface of the substrate. The substrate is cut along the centerline of the first region using a second laser; The substrate is etched to form a first texture structure on the first region and a second texture structure on the cut surface of the substrate.

[0016] In one possible design, when the first laser creates the groove on the first surface of the substrate, the power of the first laser is 30W-200W, the scanning speed of the first laser is 15m / s-70m / s, the frequency of the first laser is 600KHz-1200KHz, and the spot size of the laser emitted by the first laser is 100um-1000um.

[0017] In one possible design, when the second laser cuts the substrate along the centerline of the first region, the power of the second laser is 100W-1000W, the scanning speed of the second laser is 15m / s-70m / s, and the spot size of the laser emitted by the second laser is 10um-100um.

[0018] This application provides a stacked battery in a third aspect, the stacked battery including a top battery, an intermediate connecting layer and a bottom battery, the intermediate connecting layer being connected between the top battery and the bottom battery; The top cell is one of a perovskite cell, a cadmium telluride solar cell, a copper indium gallium selenide solar cell, or a gallium arsenide solar cell, and the bottom cell is a solar cell described above or a solar cell prepared by the solar cell preparation method described above.

[0019] This application provides a photovoltaic module in a fourth aspect, the photovoltaic module including a first cover plate, a first encapsulating film, a battery string, a second encapsulating film and a second cover plate stacked together; The battery string includes multiple electrically connected solar cells or tandem cells, wherein the solar cells are the solar cells described above, or solar cells prepared by the solar cell preparation method described above, or the tandem cells are the tandem cells described above.

[0020] The beneficial effects of the embodiments of this application are as follows: by first performing localization processing on the cutting position on the first surface to form a first region, making the first region closer to the substrate, and cutting at the center position of the first region, the area of ​​the first surface near the third surface is a first region that is recessed towards the substrate. Subsequently, the first region and the third surface are etched to remove the PN junction damage area and microcracks in the first region and the third surface, reduce the recombination rate, and increase the open circuit voltage and circuit current, so as to improve the conversion efficiency of the solar cell.

[0021] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0022] Figure 1 This is a cross-sectional schematic diagram of the photovoltaic module provided in this application in one embodiment; Figure 2 A cross-sectional schematic diagram of a solar cell provided in this application in one embodiment; Figure 3 A cross-sectional schematic diagram of the solar cell provided in this application in another embodiment; Figure 4 for Figure 3 Measured diagram of the connection between Zone 1 and Zone 2; Figure 5 for Figure 3 Measured diagram of the connection between Zone 1 and Zone 2; Figure 6 A cross-sectional schematic diagram of the solar cell provided in this application in another embodiment; Figure 7 A cross-sectional schematic diagram of the solar cell provided in this application in another embodiment; Figure 8 The preparation provided for this application Figure 2 The diagram shows a flow chart of a solar cell. Figure 9 The preparation provided for this application Figure 2 The diagram shows a flow chart of a solar cell. Figure 10 The preparation provided for this application Figure 2 The diagram shows a flow chart of a solar cell. Figure 11 The preparation provided for this application Figure 2 The diagram shows a flow chart of a solar cell. Figure 12 A schematic diagram showing the groove on the first surface; Figure 13 for Figure 2 A measured view of the cut surface of the solar cell shown. Figure 14 for Figure 2 A measured view of the surface of the first region of the solar cell shown. Figure 15 The preparation provided for this application Figure 3 The diagram shows a flow chart of a solar cell. Figure 16 for Figure 3 A measured view of the cut surface of the solar cell shown. Figure 17 for Figure 3 A measured view of the first side of the solar cell shown. Figure 18 The preparation provided for this application Figure 6 The flowchart of the solar cell shown is as follows. Figure 19 The preparation provided for this application Figure 6 The diagram shows a flow chart of a solar cell. Figure 20 The preparation provided for this application Figure 6 The diagram shows a flow chart of a solar cell. Figure 21 A schematic diagram for creating a groove on the second surface; Figure 22 The preparation provided for this application Figure 7 The diagram shows a flow chart of a solar cell. Figure 23 The preparation provided for this application Figure 2 The diagram shows a flow chart of a solar cell in another embodiment; Figure 24 The preparation provided for this application Figure 2The diagram shows a flow chart of a solar cell in another embodiment; Figure 25 The preparation provided for this application Figure 2 The diagram shows a flow chart of a solar cell in another embodiment; Figure 26 The preparation provided for this application Figure 2 The diagram shows a flow chart of a solar cell in another embodiment; Figure 27 The preparation provided for this application Figure 3 The diagram shows a flow chart of a solar cell in another embodiment; Figure 28 This is a schematic diagram of the process for fabricating a solar cell according to another embodiment of the present application; Figure 29 This is a schematic diagram of the process for fabricating a solar cell according to another embodiment of the present application; Figure 30 This is a schematic diagram of the process for fabricating a solar cell according to another embodiment of the present application; Figure 31 This is a schematic diagram of the process for fabricating a solar cell according to another embodiment of the present application.

[0023] Figure label: 100 - Photovoltaic modules; 101 - First cover plate; 102 - First adhesive film; 103-Battery string; 104 - Second film; 105 - Second cover plate; 10-Solar cells; 11-Base; 11a - First page; 111-First District; 111a - First texture structure; 111b - Inclined plane; 111c - Conical structure; 112 - Second District; 112a - The third pyramid structure; 114 - Groove; 115 - First end; 116 - Second end; 11a1-borosilicate glass; 11a2-Silica; 11a3-Polycrystalline silicon; 11a4-phosphosilicate glass; 11b - Second page; 11b1 - Zone 3; 11b2 - Fourth Zone; 11c - Third face; 113 - Second texture structure; 117 - Third end; 118 - Fourth end; 12-Emitter; 13-Passivation layer; 14 - First antireflective layer; 16-Tunneling oxide layer; 17-Doped polycrystalline silicon layer; 18 - Second antireflective layer; 20 - First laser; 30 - Second laser.

[0024] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. Detailed Implementation

[0025] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0026] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0027] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0028] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0029] It should be noted that the directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this application are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when it is mentioned that an element is connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected to the other element "upper" or "lower" through an intermediate element.

[0030] This application relates to the field of photovoltaic power generation technology, where the photovoltaic module 100 is the core component that converts solar energy into electrical energy. Figure 1 The diagram shows the structure of a photovoltaic module 100. The photovoltaic module 100 includes a first cover plate 101, a first encapsulant film 102, a battery string 103, a second encapsulant film 104, and a second cover plate 105 stacked along its thickness direction Z. The first cover plate 101 and the battery string 103 are sealed and fixed together by the first encapsulant film 102, and the second cover plate 105 and the battery string 103 are sealed and fixed together by the second encapsulant film 104.

[0031] Specifically, the first cover plate 101 and / or the second cover plate 105 can be photovoltaic glass with high light transmittance, such as double-coated glass. The first cover plate 101 and the second cover plate 105 are used to protect the internal encapsulation material and the battery string 103 from mechanical damage and external environmental corrosion, and have waterproof and moisture-proof capabilities. During the lamination process of the photovoltaic module 100, the first encapsulant film 102 and the second encapsulant film 104 are used to encapsulate the battery string 103, preventing the external environment from affecting the performance of the battery string 103, and at the same time, they can also bond the first cover plate 101, the battery string 103 and the second cover plate 105 into a whole.

[0032] The battery string 103 can be one or more. If there are multiple battery strings 103, they can be connected in series, in parallel, or in a mixed configuration. A mixed configuration means that multiple battery strings 103 are connected in both series and parallel, which can provide higher voltage and capacity. One end of the busbar is connected to the battery string 103, and the other end is connected to the junction box to lead the electrical energy generated by the photovoltaic module 100 to an external load.

[0033] The materials of the first film 102 and the second film 104 can be one of the following: ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), polyvinyl butyral (PVB), etc., or they can be EPE film (EVA-POE-EVA co-extrusion structure) or EP film (EVA-EP co-extrusion structure).

[0034] It is understood that other layers may be provided between the first cover plate 101 and the first adhesive film 102, between the first adhesive film 102 and the battery string 103, between the battery string 103 and the second adhesive film 104, and between the second adhesive film 104 and the second cover plate 105. The specific number of layers of the photovoltaic module 100 can be set according to the actual situation, and this embodiment does not limit it.

[0035] In this embodiment, the photovoltaic module 100 connects individual solar cells 10 in series and parallel, encapsulates them, and connects them with external wires to form a solar cell module 10 that can be used independently as a photovoltaic power source. The photovoltaic module 100 absorbs sunlight and uses the photovoltaic effect to directly convert solar radiation energy into the required electrical energy output.

[0036] Figure 2 This is a cross-sectional schematic diagram of the solar cell 10 in one embodiment. Along the thickness direction Z of the solar cell 10, the solar cell 10 includes a substrate 11. The substrate 11 has a first surface 11a, a second surface 11b, and a third surface 11c. The first surface 11a and the second surface 11b are arranged opposite to each other along the thickness direction Z of the solar cell 10. Along the length direction Y of the solar cell 10, the third surface 11c is located on the same side of the first surface 11a and the second surface 11b, and the third surface 11c connects the first surface 11a and the second surface 11b.

[0037] In some embodiments, the material of the substrate 11 can be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon. The elemental semiconductor material can be monocrystalline, polycrystalline, amorphous, or microcrystalline (possessing both monocrystalline and amorphous states is called microcrystalline). For example, silicon can be at least one of monocrystalline silicon, polycrystalline silicon 11a3, amorphous silicon, or microcrystalline silicon.

[0038] In some embodiments, the substrate 11 may be an N-type semiconductor substrate 11. The N-type semiconductor substrate 11 is doped with an N-type element, which may be at least one of group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As).

[0039] In some embodiments, the first surface 11a of the substrate 11 can be the front surface, and the second surface 11b can be the back surface. When the solar cell 10 is a single-sided cell, the first surface 11a can be the light-receiving surface, used to receive incident light, and the second surface 11b can be the back surface. When the solar cell 10 is a bi-sided cell, both the first surface 11a and the second surface 11b can be light-receiving surfaces and can both be used to receive incident light. The second surface 11b can also receive incident light, but its efficiency in receiving incident light is weaker than that of the first surface 11a.

[0040] The first surface 11a has a textured surface, which is a regular pyramidal structure. The tilt angle of the pyramidal structure can increase the internal reflection of incident light, thereby improving the absorption and utilization rate of incident light by the substrate 11, and thus improving the cell efficiency of the solar cell 10.

[0041] The second surface 11b may have a velvety texture, or it may not have a velvety texture. The specific design can be determined according to the actual situation, and this embodiment does not impose any limitations on it.

[0042] The third surface 11c of the substrate 11 is a cut surface, which is the side surface formed after the multi-segmented battery is segmented by laser.

[0043] After multi-segmented solar cells are segmented using lasers, a mechanical damage layer is introduced into the cut surface and beneath it, resulting in microcracks on the cut surface and introducing numerous recombination centers. Simultaneously, PN junction damage areas exist at the edges of the segments, leading to edge leakage. Although multi-segment passivation technology can improve the passivation effect by forming an alumina film layer on the cut surface to passivate and repair the cracks, the cracks still remain, making recombination difficult to avoid. Furthermore, the disruption of the PN junction continuity at the cut surface, with numerous cracks forming in the junction region, increases leakage.

[0044] To resolve the above technical issues, please continue to refer to [the relevant documentation / reference]. Figure 2 In some embodiments, the first surface 11a has a first region 111 ( Figure 2 The area within the midpoint of the line frame) and the second area 112 ( Figure 2 (The area within the dashed box is shown). The first region 111 is located on the side closer to the third surface 11c, and the second region 112 is located on the side farther from the third surface 11c. Along the thickness direction Z of the solar cell 10, the distance between the first region 111 and the second surface 11b is less than the distance between the second region 112 and the second surface 11b. Specifically, the distance between the first region 111 and the second surface 11b refers to the distance between the end of the first region 111 furthest from the second surface 11b and the second surface 11b. The distance between the second region 112 and the second surface 11b refers to the distance between the end of the second region 112 furthest from the second surface 11b and the second surface 11b.

[0045] That is, the first region 111 is a region that is recessed downwards from the first surface 11a compared to the second region 112. Both the first region 111 and the third surface 11c have textured structures formed by etching. Specifically, the first region 111 forms a first textured structure 111a, and the third surface 11c forms a second textured structure 113. The reflectivity of the first textured structure 111a is less than or equal to the reflectivity of the second textured structure 113.

[0046] In other words, in this embodiment, when the multi-segment battery is segmented, the first surface 11a of the multi-segment battery is processed by laser to form a first region 111, that is, the first surface 11a is first localized. Then, laser cutting is performed along the center of the first region 111, and the cutting surface is the third surface 11c. Then, the first region 111 and the third surface 11c are etched to form a textured structure on the surfaces of both the first region 111 and the third surface 11c.

[0047] Because microcracks can form on the first surface 11a near the third surface 11c during laser processing of multi-segment solar cells, damaging the PN junction, this embodiment first localizes the cutting position on the first surface 11a to form a first region 111, bringing the first region 111 closer to the substrate 11. A cut is then made at the center of the first region 111, so that the area of ​​the first surface 11a near the cut surface (third surface 11c) is a recessed area facing the substrate 11 (first region 111). Subsequently, the first region 111 and the third surface 11c are etched to remove the PN junction damage area and microcracks in the first region 111 and the third surface 11c, reducing the recombination rate and increasing the open-circuit voltage and circuit current, thereby improving the conversion efficiency of the solar cell 10. In some embodiments, the distance between the first region and the second surface is D1, and the distance between the second region and the second surface is D2, with the difference between D2 and D1 being 1μm-5μm. That is, the depth of the first region 111 can be 1μm-5μm.

[0048] For example, the depth of the first region 111 can be 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, etc., and can be set according to the actual situation. This embodiment does not limit it here.

[0049] In this embodiment, the depth of the first region 111 is set to 1μm to 5μm, so that the first region 111 is close to the substrate 11 while reducing the risk of damaging the substrate 11.

[0050] In some embodiments, the width of the first region 111 can be 50μm-500μm.

[0051] For example, the width of the first region 111 can be 50μm, 100μm, 150μm, 200μm, 250μm, 300μm, 350μm, 400μm, 450μm, 500μm, etc., and can be set according to the actual situation. This embodiment does not limit it here.

[0052] In this embodiment, the width of the first region 111 is set to be between 50μm and 500μm, so as to etch away the PN junction damage region of the first surface 11a near the third surface 11c, while reducing the loss of the emitter 12 on the first surface 11a and ensuring the photoelectric conversion efficiency.

[0053] It is understandable that the width of the first region 111 is 50μm-500μm. Etching away the emitter 12 of the first region 111 will not affect the conversion efficiency of the solar cell 10. On the contrary, it can etch away the PN junction damage area and microcracks of the first region 111, reduce leakage current, increase parallel resistance, and improve filling, thereby helping to improve the conversion efficiency of the solar cell 10.

[0054] Please continue to refer to this. Figure 2 The connection point between the first region 111 and the second region 112 can have an inclined angle. By etching the first region, the connection point between the first region 111 and the second region 112 is etched at an inclined angle.

[0055] In some embodiments, the tilt angle can be 50°-120°. That is, the angle between the tilt angle and the first region 111 is 50°-120°, and the angle between the tilt angle and the second region 112 is 50°-120°.

[0056] For example, the tilt angle can be 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, 90°, 95°, 100°, 105°, 110°, 115°, 120°, etc., and can be set according to the actual situation. This embodiment does not limit it.

[0057] In this embodiment, the tilt angle is set between 50° and 120°, which can reduce reflection, enhance the light trapping effect, and help improve the conversion efficiency of the solar cell 10.

[0058] In some embodiments, the junction between the first region 111 and the second region 112 can be etched into a regular bevel 111b.

[0059] In some embodiments, the junction of the first region 111 and the second region 112 is etched with multiple conical structures 111c, which helps to further reduce reflection, enhance the light trapping effect, and improve the conversion efficiency of the solar cell 10.

[0060] In some embodiments, the doping concentration of the second region 112 is greater than the doping concentration of the first region 111.

[0061] Please continue to refer to this. Figure 2The first region 111 of the first surface 11a is provided with a passivation layer 13 and a first antireflection layer 14 in sequence. The second region 112 of the first surface 11a is provided with an emitter 12, a passivation layer 13, and a first antireflection layer 14 in sequence. The third surface 11c is provided with a passivation layer 13. The second surface 11b is provided with a tunneling oxide layer 16, a doped polysilicon layer 17, and a second antireflection layer 18 in sequence. That is to say, the first region 111 of the first surface 11a lacks an emitter 12 compared to the second region 112 of the first surface 11a.

[0062] Specifically, in this embodiment, after phosphorus diffusion, a first region 111 is formed on the first surface 11a. A cut is made at the center of the first region 111, and then the substrate 11 is etched to form a textured structure between the first region 111 and the third surface 11c. Subsequently, the first surface 11a, the second surface 11b, and the third surface 11c are passivated. This embodiment, by forming the first region 111 after phosphorus diffusion and then etching it, removes the emitter 12 of the first region 111, thereby eliminating the PN junction damage area and microcracks in the first region 111, thus minimizing leakage current caused by reduced PN junction continuity. Furthermore, by etching the third surface 11c, microcracks on the third surface 11c are eliminated, thereby removing recombination centers, reducing leakage current, improving passivation effect, and increasing short-circuit current. Passivating the third surface 11c reduces the recombination velocity of charge carriers on the third surface 11c, improving the photoelectric conversion efficiency of the solar cell. The passivation layer material can be silicon oxide, aluminum oxide, silicon nitride, etc.

[0063] In some embodiments, the reflectivity of the first texture structure 111a of the first region 111 is less than the reflectivity of the conical structure 111c.

[0064] In some embodiments, the height of the tapered structure 111c can be 0.5 μm-1 μm.

[0065] For example, the height of the conical structure 111c can be 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, etc., and can be set according to the actual situation. This embodiment does not limit it.

[0066] In this embodiment, the height of the conical structure 111c is set to be between 0.5μm and 1μm, which increases the reflection at the connection between the first region 111 and the second region 112, extends the light propagation path, and increases the light absorption effect.

[0067] In some embodiments, the first texture structure 111a of the first region 111 can be a first pyramid structure, and the height of the first pyramid structure can be 1μm-2μm.

[0068] For example, the height of the first pyramid structure can be 1μm, 1.1μm, 1.1μm, 1.1μm, 1.1μm, 1.1μm, 1.1μm, 1.1μm, 1.1μm, 1.1μm, 1.1μm, 1.1μm, etc., and can be set according to the actual situation. This embodiment does not limit it here.

[0069] In this embodiment, the height of the first pyramid structure is set between 1μm and 2μm to increase the reflection of light illuminating the first area 111, extend the light propagation path, and increase the light absorption effect.

[0070] In some embodiments, the reflectivity of the first pyramid structure can be 9%-12%.

[0071] For example, the reflectivity of the first pyramid structure can be 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, etc., and can be set according to the actual situation. This embodiment does not limit it here.

[0072] In some embodiments, the second region 112 is provided with a third pyramid structure 112a, the height of which is 0.8μm-2μm.

[0073] For example, the height of the third pyramid structure 112a can be 0.8μm, 0.85μm, 0.9μm, 0.95μm, 0.1μm, 0.15μm, or 0.2μm. The specific value can be set according to the actual situation, and this embodiment does not limit it.

[0074] Among them, the reflectivity of the third pyramid structure 112a can be 11%-15%.

[0075] For example, the reflectivity of the third pyramid structure 112a can be 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, etc., and can be set according to the actual situation. This embodiment does not limit it here.

[0076] In other words, the reflectivity of the first pyramid structure is 2%-3% lower than that of the third pyramid. That is, the reflectivity of the first region 111 on the first face 11a is lower than that of the second region 112, thereby improving the utilization rate of light energy in the first region 111.

[0077] For example, the reflectivity of the first pyramid structure may be 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, etc., lower than that of the third pyramid structure 112a. The specific reflectivity can be set according to the actual situation, and this embodiment does not limit it.

[0078] The second texture structure 113 on the third surface 11c can be a second pyramid structure, with a height of 0.5μm-2μm.

[0079] For example, the height of the second pyramid structure can be 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1.0μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, etc., and can be set according to the actual situation. This embodiment does not limit it.

[0080] In this embodiment, the third surface 11c is set as a pyramid structure, which can reflect and scatter the light that shines on the third surface 11c multiple times, greatly increasing the probability of light entering the inside of the battery, which is beneficial to improving light utilization and increasing short-circuit current.

[0081] The substrate 11 can be etched using a texturing process to form a first pyramid structure in the first region 111 and a second pyramid structure in the third surface 11c. Since the first region 111 is the front side and the third surface 11c is the cut surface, the substrate 11 is directly exposed from the third surface 11c. The substrate 11 is made of silicon, and the etching effect is poor. Therefore, the height of the first pyramid structure is different from the height of the second pyramid structure.

[0082] Please refer to Figure 3 , Figure 3 This is a cross-sectional schematic diagram of the solar cell 10 in another embodiment. In some embodiments, the first texture structure 111a of the first region 111 can be a first tower base structure. The side length of the first tower base structure can be 3μm-30μm, and the reflectivity of the first tower base structure is 25%-45%.

[0083] For example, the side length of the first tower base structure can be 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm, 30μm, etc., and can be set according to the actual situation. This embodiment does not limit it.

[0084] The reflectivity of the first tower base structure can be 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, etc., and can be set according to the actual situation. This embodiment does not limit it.

[0085] In this embodiment, setting the first region 111 as a tower base structure can improve the flatness of the first region 111, which is beneficial to improving the quality of the film layer in subsequent coating and increasing the open circuit voltage.

[0086] Please continue to refer to this. Figure 3 In some embodiments, the second texture structure 113 of the third surface 11c can be a second base structure with a side length of 3μm-30μm and a reflectivity of 25%-45%.

[0087] For example, the side length of the second tower base structure can be 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm, 30μm, etc., and can be set according to the actual situation. This embodiment does not limit it.

[0088] The reflectivity of the second tower base structure can be 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, etc., and can be set according to the actual situation. This embodiment does not limit it.

[0089] In this embodiment, setting the third surface 11c as a tower base structure can improve the flatness of the third surface 11c, thereby improving the quality of the subsequent coating and increasing the open-circuit voltage. Setting the first region 111 and the third surface 11c as a pyramid structure or a tower base structure can be set according to the actual situation, and this embodiment does not limit it.

[0090] Figure 4 and Figure 5 for Figure 3 The middle section shows the measured location of the connection between Zone 111 and Zone 212. Figure 4 This is a schematic diagram showing the solar cell as viewed from the side. Figure 5 This is a schematic diagram showing the view of a solar cell from above. Please refer to the reference. Figure 4 and Figure 5Multiple conical structures 111c are provided at the connection between the first region 111 and the second region 112, making the connection surface of the first region 111 and the second region 112 have a continuous concave-convex shape. The multiple conical structures 111c can be regular structures, evenly distributed along the cutting direction when the first surface of the laser-processed substrate is being processed. Alternatively, the multiple conical structures 111c can also be irregular structures, distributed along the cutting direction when the first surface of the laser-processed substrate is being processed. Please refer to [reference needed]. Figure 6 , Figure 6 This is a cross-sectional schematic diagram of the solar cell 10 in another embodiment. In some embodiments, when the multi-segmented cell is segmented, the second surface 11b of the multi-segmented cell can be laser-processed to form a third region 11b1 on the second surface 11b. Then, laser cutting is performed along the center of the third region 11b1, and the cut surface is the third surface 11c. The third region 11b1 and the third surface 11c are etched to form a textured structure on the surfaces of both the third region 11b1 and the third surface 11c.

[0091] Please continue to refer to this. Figure 6 The first surface 11a is sequentially provided with an emitter 12, a passivation layer 13, and a first antireflection layer 14. The third region 11b1 of the second surface 11b is provided with a second antireflection layer 18. The fourth region 11b2 of the second surface 11b is sequentially provided with a tunneling oxide layer 16, a doped polysilicon layer 17, and a second antireflection layer 18. That is to say, the third region 11b1 of the second surface 11b lacks the tunneling oxide layer 16 and the doped polysilicon layer 17 compared to the fourth region 11b2 of the second surface 11b.

[0092] Specifically, in this embodiment, after phosphor diffusion, a third region 11b1 is formed on the second surface 11b. A cut is made at the center of the third region 11b1, and then the substrate 11 is etched to create a textured structure between the third region 11b1 and the third surface 11c. Subsequently, the first surface 11a, the third surface 11c, and the third surface 11c are passivated. This embodiment eliminates microcracks at the third region 11b1 and the third surface 11c by etching, thereby removing the composite center, reducing leakage current, improving the passivation effect, and increasing the short-circuit current.

[0093] Please continue to refer to this. Figure 6 The texture structure of the third region 11b1 and the third surface 11c can be a pyramid structure. For details, please refer to the above embodiment. This embodiment will not repeat the details here.

[0094] Alternatively, please refer to Figure 7 , Figure 7 This is a cross-sectional schematic diagram of the solar cell 10 in another embodiment. The textured structure of the third region 11b1 and the third surface 11c can also be a tower-based structure. For details, please refer to the above text. Figure 3The details of the embodiments will not be repeated here.

[0095] Alternatively, in some embodiments, after boron expansion, a first region 111 can be opened on the first surface 11a, and a cut can be made at the center of the first region 111.

[0096] Alternatively, in some embodiments, cutting can be performed at the center of the second surface 11b after boron expansion. In this embodiment, the process of creating the third region 11b1 on the second surface 11b after boron expansion can be omitted because the alkaline polishing process can remove the backside PN junction, eliminating the need for localization processing.

[0097] The following section will describe in detail the possible fabrication methods of the solar cell 10 with reference to the accompanying drawings.

[0098] Please refer to the reference. Figure 8 , Figure 9 , Figure 10 and Figure 11 ,based on Figure 2 The solar cell 10 shown can be fabricated by a method that includes: S11: Texturing the first surface 11a of the substrate 11 to form a pyramid structure on the first surface 11a, reducing the reflectivity of the first surface 11a, and removing mechanical damage to the first surface 11a.

[0099] Alternatively, the first surface 11a and the second surface 11b of the substrate 11 can be texturized to form a pyramid structure, reducing the reflectivity of the first surface 11a and the second surface 11b while removing mechanical damage to the first surface 11a and the second surface 11b. Specific configurations can be made according to actual conditions, and this embodiment does not impose limitations.

[0100] S12: Boron doping is performed on substrate 11 to form a PN junction, thereby realizing the conversion of light energy into electrical energy. The first surface 11a sequentially forms an emitter 12 and borosilicate glass 11a1, and the second surface 11b sequentially forms an emitter 12 and borosilicate glass 11a1.

[0101] S13: Perform alkaline polishing on the second surface 11b to remove excess PN junctions and prevent short circuits caused by the formation of a diffusion layer around the second surface 11b. That is, remove the emitter 12 and borosilicate glass 11a1 from the second surface 11b.

[0102] S14: Deposit SiO2 to form a tunneling oxide layer 16 to provide good interface passivation, and deposit amorphous silicon to form an amorphous silicon layer. Perform phosphorus doping to transform the amorphous silicon layer into a doped polycrystalline silicon layer 17. That is, the first surface 11a sequentially forms an emitter 12, borosilicate glass 11a1, silicon oxide 11a2, polycrystalline silicon 11a3, and phosphorosilicate glass 11a4, and the second surface 11b sequentially forms a tunneling oxide layer 16, a doped polycrystalline silicon layer 17, and phosphorosilicate glass 11a4.

[0103] S15: A groove 114 is formed at the cutting position of the first surface 11a using the first laser 20, so that the first surface 11a forms a first region 111 and a second region 112. At this time, the silicon oxide 11a2, polycrystalline silicon 11a3, and phosphosilicate glass 11a4 of the first region 111 are removed. The distance between the first region 111 and the second surface 11b is less than the distance between the second region 112 and the second surface 11b.

[0104] S16: The second laser 30 is used to cut the substrate 11 along the centerline of the first region 111, so that the side of the substrate 11 has a cut surface, which is the third surface 11c mentioned above. Please refer to the following for details. Figure 13 , Figure 13 This is a measured diagram of the third face 11c.

[0105] S17: Etch the substrate 11 to create a textured structure between the first region 111 and the cut surface (third surface 11c) of the substrate 11. Please refer to [reference needed] for details. Figure 14 , Figure 14 This is a measured view of the surface of the first region 111. At this point, the borosilicate glass 11a1 and emitter 12 of the first region 111 on the first surface 11a have been removed; the borosilicate glass 11a1, silicon oxide 11a2, polysilicon 11a3, and phosphosilicate glass 11a4 of the second region 112 on the first surface 11a have also been removed; and the phosphosilicate glass 11a4 of the second surface 11b has been removed. That is, the second region 112 of the first surface 11a now has the emitter 12, and the second surface 11b has a tunneling oxide layer 16 and a doped polysilicon layer 17.

[0106] S18: Al2O3 electrodes are deposited on the first surface 11a and the third surface 11c to form a passivation layer 13. SiNx is deposited on the passivation layer 13 to form a first antireflection layer 14. SiNx is deposited on the second surface 11b to form a second antireflection layer 18. At this time, the first region 111 on the first surface 11a has the passivation layer 13 and the first antireflection layer 14 formed sequentially. The second region 112 on the first surface 11a has the emitter 12, the passivation layer 13 and the first antireflection layer 14 formed sequentially. The second surface 11b has the tunneling oxide layer 16, the doped polysilicon layer 17 and the second antireflection layer 18 formed sequentially. The third surface 11c has the passivation layer 13 formed.

[0107] S19: Screen printing and sintering are performed on the first antireflection layer 14 to form the first electrode. Screen printing and sintering are performed on the second antireflection layer 18 to form the second electrode. The first electrode and the second electrode can collect the current generated in the PN junction of the solar cell 10 due to light and transmit it to an external load.

[0108] Please refer to the following: Figure 12 , Figure 12 This is a schematic diagram of the first surface 11a. In step S15, when the first laser 20 creates a groove 114 on the first surface 11a, the groove 114 extends from the first end 115 of the first surface 11a to the second end 116 of the first surface 11a. That is, the first region 111 extends from the first end 115 of the first surface 11a to the second end 116 of the first surface 11a. In this embodiment, a first region 111 connecting the first end 115 and the second end 116 is provided on the first surface 11a. The first surface 11a is first localized so that the PN junction damage area and microcracks of the first region 111 can be etched in the subsequent etching process.

[0109] It is understandable that the width of the first region 111 is 50μm-500μm. Etching away the emitter 12 of the first region 111 will not affect the conversion efficiency of the solar cell 10. On the contrary, it can etch away the PN junction damage area and microcracks of the first region 111, reduce leakage current, increase parallel resistance, and improve filling, thereby helping to improve the conversion efficiency of the solar cell 10.

[0110] In some embodiments, when the first laser 20 forms a groove 114 on the first surface 11a of the substrate 11, the first laser 20 can be an ultraviolet picosecond laser, a green picosecond laser, a green nanosecond laser, etc., the power of the first laser 20 can be 30W-200W, the scanning speed of the first laser 20 can be 15m / s-70m / s, the frequency of the first laser 20 is 600KHz-1200KHz, and the spot size of the laser emitted by the first laser 20 is 100um-1000um.

[0111] For example, the power of the first laser 20 can be 30W, 40W, 50W, 60W, 70W, 80W, 90W, 100W, 110W, 120W, 130W, 140W, 150W, 160W, 170W, 180W, 190W, 200W, etc., and can be set according to the actual situation. This embodiment does not limit it.

[0112] The scanning speed of the first laser 20 can be 15m / s, 20m / s, 25m / s, 30m / s, 35m / s, 40m / s, 45m / s, 50m / s, 55m / s, 60m / s, 65m / s, 70m / s, etc., and can be set according to the actual situation. This embodiment does not limit it here.

[0113] The frequency of the first laser 20 can be 600KHz, 700KHz, 800KHz, 900KHz, 1000KHz, 1100KHz, 1200KHz, etc., and can be set according to the actual situation. This embodiment does not limit it here.

[0114] The size of the laser spot emitted by the first laser 20 can be 100um, 100um, 100um, 100um, 100um, 100um, 100um, 100um, 100um, 100um, 100um, 100um, 100um, 100um, 100um, 100um, 1000um, etc., and can be set according to the actual situation. This embodiment does not limit it here.

[0115] In this embodiment, by setting the power of the first laser 20 to between 30W and 200W, the first laser 20 forms the first region 111 on the first surface 11a while minimizing damage to the substrate 11. By setting the scanning speed of the first laser 20 to between 15m / s and 70m / s, the first laser 20 forms the first region 111 on the first surface 11a while minimizing damage to the substrate 11. By setting the spot size of the laser emitted by the first laser 20 to between 100um and 1000um, the formation of the first region 111 on the first surface 11a removes PN junction damage areas and microcracks while preventing PN junction loss and ensuring photoelectric conversion efficiency.

[0116] In some embodiments, when the second laser 30 cuts the substrate 11 along the centerline of the first region 111, the second laser 30 may use visible light laser, red light, etc., the power of the second laser 30 is 100W-1000W, the scanning speed of the second laser 30 is 15m / s-70m / s, and the spot size of the laser emitted by the second laser 30 is 10um-100um.

[0117] For example, the power of the second laser 30 can be 100W, 200W, 300W, 400W, 500W, 600W, 700W, 800W, 900W, 1000W, etc., and can be set according to the actual situation. This embodiment does not limit it here.

[0118] The scanning speed of the second laser 30 can be 15m / s, 20m / s, 25m / s, 30m / s, 35m / s, 40m / s, 45m / s, 50m / s, 55m / s, 60m / s, 65m / s, 70m / s, etc., and can be set according to the actual situation. This embodiment does not limit it here.

[0119] The size of the laser spot emitted by the second laser 30 can be 10um, 20um, 30um, 40um, 50um, 60um, 70um, 80um, 90um, 100um, etc., and can be set according to the actual situation. This embodiment does not limit it.

[0120] Please continue to refer to this. Figure 11 In some embodiments, in step S17, a texturing process can be used to etch the substrate 11 so that the first region 111 forms a first pyramid structure and the third surface 11c forms a second pyramid structure.

[0121] Specifically, the substrate 11 is placed in a texturing tank containing an alkaline solvent and texturing additives.

[0122] The alkaline solvent can be sodium hydroxide, potassium hydroxide, etc., and the amount of alkaline solvent can be set from 1L to 20L. The amount of texturing additive can be set from 1L to 10L. The reaction temperature is 60℃ to 85℃, and the reaction time is 50s to 500s.

[0123] Alternatively, please refer to Figure 15 , Figure 15 This is a schematic diagram illustrating the process of alkaline polishing and passivation after cutting the solar cell 10, so that the first region 111 forms the first tower base structure, the third surface 11c forms the second tower base structure, and finally it is manufactured as shown in the diagram. Figure 3 The solar cell 10 is shown. Please refer to the reference for details. Figure 16 and Figure 17 , Figure 16 This is a measured image of the third surface after 11c alkaline polishing and positive engraving. Figure 17 This is a measured image of the first face 11a after alkali polishing and positive engraving.

[0124] Specifically, the substrate 11 is placed in a polishing tank containing an alkaline solvent and polishing additives.

[0125] The alkaline solvent can be sodium hydroxide, potassium hydroxide, etc., and the alkaline solvent can be set at 1L-20L. The polishing additive can be set at 1L-10L. The reaction temperature is 60℃-85℃, and the reaction time is 50s-500s.

[0126] It should be noted that because the substrate 11 is silicon, and silicon is a crystal, anisotropy will occur after etching (texturing or alkaline polishing), causing the connection between the first region 111 and the second region 112 to be etched at an angle. The specific details of the angle can be found above, and will not be repeated here in this embodiment.

[0127] Understandably, when the second laser 30 cuts the substrate 11, the laser scans along a preset path on the first surface 11a, forming a continuous cutting line on the surface without cutting through the substrate 11. Cracks are guided by the cutting stress within the substrate 11, thus achieving the segmentation of the substrate 11. In other words, after the substrate 11 is cut, the PN junction damage area and microcracks caused by the second laser 30 mainly form on the third surface 11c near the first surface 11a, and at the edge of the first surface 11a near the third surface 11c. Therefore, it is sufficient to set the first region 111 on the first surface 11a where the substrate 11 is cut.

[0128] Alternatively, in some embodiments, the film can be cut from the second surface 11b of the substrate 11.

[0129] Please refer to the reference for details. Figure 9 , Figure 18 , Figure 19 and Figure 20 S21: Texturing the first surface 11a of the substrate 11 to form a pyramid structure on the first surface 11a, reducing the reflectivity of the first surface 11a, and removing mechanical damage to the first surface 11a.

[0130] Alternatively, the first surface 11a and the second surface 11b of the substrate 11 can be texturized to form a pyramid structure, reducing the reflectivity of the first surface 11a and the second surface 11b while removing mechanical damage to the first surface 11a and the second surface 11b. Specific configurations can be made according to actual conditions, and this embodiment does not impose limitations.

[0131] S22: Boron doping is performed on substrate 11 to form a PN junction, thereby realizing the conversion of light energy into electrical energy. The first surface 11a sequentially forms an emitter 12 and borosilicate glass 11a1, and the second surface 11b sequentially forms an emitter 12 and borosilicate glass 11a1.

[0132] S23: Perform alkaline polishing on the second surface 11b to remove excess PN junctions and prevent short circuits caused by the formation of a diffusion layer around the second surface 11b. That is, remove the emitter 12 and borosilicate glass 11a1 from the second surface 11b.

[0133] S24: SiO2 is deposited to form a tunneling oxide layer 16 to provide good interface passivation. Amorphous silicon is deposited to form an amorphous silicon layer. Phosphorus doping is performed to transform the amorphous silicon layer into a doped polycrystalline silicon layer 17. That is, the first surface 11a sequentially forms an emitter 12, borosilicate glass 11a1, silicon oxide 11a2, polycrystalline silicon 11a3, and phosphorus silicate glass 11a4, and the second surface 11b sequentially forms a tunneling oxide layer 16, a doped polycrystalline silicon layer 17, and phosphorus silicate glass 11a4.

[0134] S25: A groove 114 is created at the cutting position of the second surface 11b using the first laser 20, forming a third region 11b1 and a fourth region 11b2 on the second surface 11b. At this time, the phosphorus silicate glass 11a4 in the third region 11b1 is removed. The distance between the third region 11b1 and the first surface 11a is less than the distance between the fourth region 11b2 and the first surface 11a.

[0135] S26: The second laser 30 is used to cut the substrate 11 along the centerline of the third region 11b1, so that the side of the substrate 11 forms a cutting surface, which is the third surface 11c mentioned above.

[0136] S27: Etch substrate 11 to form a textured structure on the third region 11b1 and the cut surface (third surface 11c) of substrate 11. At this time, the tunneling oxide layer 16 and the doped polysilicon layer 17 of the third region 11b1 are removed, the phosphorus silicate glass 11a4 of the fourth region 11b2 is removed, and the borosilicate glass 11a1, silicon oxide 11a2, polysilicon 11a3 and phosphorus silicate glass 11a4 of the first surface 11a are removed.

[0137] S28: Al2O3 electrodes are deposited on the first surface 11a and the third surface 11c to form a passivation layer 13. SiNx is deposited on the passivation layer 13 to form a first antireflection layer 14. SiNx is deposited on the second surface 11b to form a second antireflection layer 18. At this time, the first surface 11a is sequentially formed with an emitter 12, a passivation layer 13 and a first antireflection layer 14. The third region 11b1 of the second surface 11b is formed with a second antireflection layer 18. The fourth region 11b2 of the second surface 11b is formed with a tunneling oxide layer 16, a doped polysilicon layer 17 and a second antireflection layer 18. The third surface 11c is formed with a passivation layer 13 (not shown in the figure).

[0138] S29: Screen printing and sintering are performed on the first antireflection layer 14 to form the first electrode. Screen printing and sintering are performed on the second antireflection layer 18 to form the second electrode. The first electrode and the second electrode can collect the current generated in the PN junction of the solar cell 10 due to light and transmit it to an external load.

[0139] Please refer to the following: Figure 21 , Figure 21 This is a schematic diagram of the second surface 11b. In step S25, when the first laser 20 creates a groove 114 on the second surface 11b, the groove 114 extends from the third end 117 to the fourth end 118 of the second surface 11b. That is, the third region 11b1 extends from the third end 117 to the fourth end 118 of the second surface 11b. In this embodiment, a third region 11b1 connecting the third end 117 and the fourth end 118 is provided on the third surface 11c. The second surface 11b is first localized so that the microcracks in the second region 112 can be etched in the subsequent etching process.

[0140] The width of the third zone 11b1 can be referred to the width of the first zone 111 above. The parameters of the first laser 20 and the second laser 30 can be referred to above. This embodiment will not repeat them here.

[0141] Please continue to refer to this. Figure 20 In some embodiments, in step S27, a texturing process can be used to etch the substrate 11, so that the third region 11b1 forms a first pyramid structure and the third surface 11c forms a second pyramid structure, thus creating a structure as shown in the image. Figure 6 The solar cell 10 shown.

[0142] Specifically, the substrate 11 is placed in a texturing tank containing an alkaline solvent and texturing additives.

[0143] The alkaline solvent can be sodium hydroxide, potassium hydroxide, etc., and the amount of alkaline solvent can be set from 1L to 20L. The amount of texturing additive can be set from 1L to 10L. The reaction temperature is 60℃ to 85℃, and the reaction time is 50s to 500s.

[0144] Alternatively, please refer to Figure 22 , Figure 22 This is a schematic diagram of the process of cutting solar cells 10, followed by alkaline polishing, positive etching, and passivation. The third region 11b1 forms the first tower base structure, and the third surface 11c forms the second tower base structure. Finally, it is fabricated as shown in the diagram. Figure 7 The solar cell 10 shown.

[0145] Specifically, the substrate 11 is placed in a polishing tank containing an alkaline solvent and polishing additives.

[0146] The alkaline solvent can be sodium hydroxide, potassium hydroxide, etc., and the alkaline solvent can be set at 1L-20L. The polishing additive can be set at 1L-10L. The reaction temperature is 60℃-85℃, and the reaction time is 50s-500s.

[0147] Alternatively, in some embodiments, the first surface 11a may be cut after boron expansion.

[0148] Please refer to the details. Figure 23 , Figure 24 , Figure 25 and Figure 26 S31: Texturing the first surface 11a of the substrate 11 to form a pyramid structure on the first surface 11a, reducing the reflectivity of the first surface 11a, and removing mechanical damage to the first surface 11a.

[0149] Alternatively, the first surface 11a and the second surface 11b of the substrate 11 can be texturized to form a pyramid structure, reducing the reflectivity of the first surface 11a and the second surface 11b while removing mechanical damage to the first surface 11a and the second surface 11b. Specific configurations can be made according to actual conditions, and this embodiment does not impose limitations.

[0150] S32: Boron doping is performed on substrate 11 to form a PN junction, thereby realizing the conversion of light energy into electrical energy. The first surface 11a sequentially forms an emitter 12 and borosilicate glass 11a1, and the second surface 11b sequentially forms an emitter 12 and borosilicate glass 11a1.

[0151] S33: A groove 114 is formed at the cutting position of the first surface 11a using the first laser 20, so that the first surface 11a forms a first region 111 and a second region 112. At this time, the borosilicate glass 11a1 of the first region 111 is removed. The distance between the first region 111 and the second surface 11b is less than the distance between the second region 112 and the second surface 11b.

[0152] S34: The second laser 30 is used to cut the substrate 11 along the centerline of the first region 111, so that the side of the substrate 11 forms a cutting surface, which is the third surface 11c mentioned above.

[0153] S35: Perform alkaline polishing on the second surface 11b to remove excess PN junctions and prevent short circuits caused by the formation of a diffusion layer around the second surface 11b. That is, remove the emitter 12 of the first surface 11a, and remove the emitter 12 and borosilicate glass 11a1 of the second surface 11b.

[0154] S36: SiO2 is deposited to form a tunneling oxide layer 16 to provide good interface passivation, and amorphous silicon is deposited to form an amorphous silicon layer. Phosphorus doping is performed to transform the amorphous silicon layer into a doped polycrystalline silicon layer 17. That is, silicon oxide 11a2, polycrystalline silicon 11a3 and phosphosilicate glass 11a4 are sequentially formed in the first region 111 of the first surface 11a, and an emitter 12, borosilicate glass 11a1, silicon oxide 11a2, polycrystalline silicon 11a3 and phosphosilicate glass 11a4 are sequentially formed in the second region 112 of the first surface 11a, and an emitter 12, borosilicate glass 11a1, silicon oxide 11a2, polycrystalline silicon 11a3 and phosphosilicate glass 11a4 are sequentially formed in the second surface 11b, and a tunneling oxide layer 16, a doped polycrystalline silicon layer 17 and phosphosilicate glass 11a4 are sequentially formed.

[0155] S37: Etch substrate 11 to form a textured structure on the first region 111 and the cut surface (third surface 11c) of substrate 11. At this time, silicon oxide 11a2, polysilicon 11a3 and phosphosilicate glass 11a4 of the first region 111 are removed, borosilicate glass 11a1, silicon oxide 11a2, polysilicon 11a3 and phosphosilicate glass 11a4 of the second region 112 are removed, and phosphosilicate glass 11a4 of the second surface 11b is removed.

[0156] S38: Al2O3 electrodes are deposited on the first surface 11a and the third surface 11c to form a passivation layer 13. SiNx is deposited on the passivation layer 13 to form a first antireflection layer 14. SiNx is deposited on the second surface 11b to form a second antireflection layer 18. At this time, the first region 111 of the first surface 11a has the passivation layer 13 and the first antireflection layer 14 formed sequentially. The second region 112 of the first surface 11a has the emitter 12, the passivation layer 13 and the first antireflection layer 14 formed sequentially. The second surface 11b has the tunneling oxide layer 16, the doped polysilicon layer 17 and the second antireflection layer 18 formed sequentially. The third surface 11c has the passivation layer 13 (not shown in the figure).

[0157] S39: Screen printing and sintering are performed on the first antireflection layer 14 to form the first electrode. Screen printing and sintering are performed on the second antireflection layer 18 to form the second electrode. The first electrode and the second electrode can collect the current generated in the PN junction of the solar cell 10 due to light and transmit it to an external load.

[0158] Please continue to refer to this. Figure 26 In some embodiments, in step S37, a texturing process can be used to etch the substrate 11, forming a first pyramid structure in the first region 111 and a second pyramid structure in the third surface 11c, thus creating a structure as shown. Figure 2 The solar cell 10 shown.

[0159] Alternatively, please refer to Figure 27 , Figure 27 This is a schematic diagram of the process of cutting solar cells 10, followed by alkaline polishing, positive etching, and passivation. The first region 111 forms the first tower base structure, and the third surface 11c forms the second tower base structure, resulting in a structure as shown below. Figure 3 The solar cell 10 shown.

[0160] Alternatively, in some embodiments, the second surface 11b may be cut after boron expansion.

[0161] Please refer to the details. Figure 28 , Figure 29 , Figure 30 and Figure 31 S41: Texturing the first surface 11a of the substrate 11 to form a pyramid structure on the first surface 11a, reducing the reflectivity of the first surface 11a, and removing mechanical damage to the first surface 11a.

[0162] Alternatively, the first surface 11a and the second surface 11b of the substrate 11 can be texturized to form a pyramid structure, reducing the reflectivity of the first surface 11a and the second surface 11b while removing mechanical damage to the first surface 11a and the second surface 11b. Specific configurations can be made according to actual conditions, and this embodiment does not impose limitations.

[0163] S42: Boron doping is performed on substrate 11 to form a PN junction, thereby realizing the conversion of light energy into electrical energy. The first surface 11a is formed with an emitter 12 and borosilicate glass 11a1 in sequence, and the second surface 11b is formed with an emitter 12 and borosilicate glass 11a1 in sequence.

[0164] S43: The second laser 30 is used to cut the substrate 11 along the cutting position of the second surface 11b, so that the side of the substrate 11 forms a cutting surface, which is the third surface 11c mentioned above.

[0165] S44: Perform alkaline polishing on the second surface 11b to remove excess PN junctions and prevent short circuits caused by the formation of a diffusion layer around the second surface 11b. That is, remove the emitter 12 and borosilicate glass 11a1 from the second surface 11b.

[0166] S45: SiO2 is deposited to form a tunneling oxide layer 16 to provide good interface passivation. Amorphous silicon is deposited to form an amorphous silicon layer. Phosphorus doping is performed to transform the amorphous silicon layer into a doped polycrystalline silicon layer 17. That is, the first surface 11a sequentially forms an emitter 12, borosilicate glass 11a1, silicon oxide 11a2, polycrystalline silicon 11a3, and phosphorus silicate glass 11a4, and the second surface 11b sequentially forms a tunneling oxide layer 16, a doped polycrystalline silicon layer 17, and phosphorus silicate glass 11a4.

[0167] S46: Etch substrate 11 to remove borosilicate glass 11a1, silicon oxide 11a2, polysilicon 11a3 and phosphosilicate glass 11a4 from the first surface 11a, and remove phosphosilicate glass 11a4 from the second surface 11b.

[0168] S47: Al2O3 electrodes are deposited on the first surface 11a and the third surface 11c to form a passivation layer 13. SiNx is deposited on the passivation layer 13 to form a first antireflection layer 14. SiNx is deposited on the second surface 11b to form a second antireflection layer 18. At this time, the first surface 11a is sequentially formed with an emitter 12, a passivation layer 13 and a first antireflection layer 14, the second surface 11b is sequentially formed with a tunneling oxide layer 16, a doped polysilicon layer 17 and a second antireflection layer 18, and the third surface is formed with a passivation layer 13 (not shown in the figure).

[0169] S48: Screen printing and sintering are performed on the first antireflection layer 14 to form the first electrode. Screen printing and sintering are performed on the second antireflection layer 18 to form the second electrode. The first electrode and the second electrode can collect the current generated in the PN junction of the solar cell 10 due to light and transmit it to an external load.

[0170] Understandably, in this embodiment, the process of opening the third region 11b1 on the second surface 11b after boron expansion can be omitted, because the alkaline polishing process can remove the back PN junction, and localization processing is not required.

[0171] In other embodiments, solar cells 10 may also be prepared using other preparation processes, which are not limited to this embodiment.

[0172] This application also provides a tandem solar cell, which includes a top cell, an intermediate connecting layer, and a bottom cell, with the intermediate connecting layer connecting the bottom cell and the top cell. The top cell is one of a perovskite solar cell, a cadmium telluride solar cell, a copper indium gallium selenide solar cell, or a gallium arsenide solar cell, and the bottom cell is the aforementioned solar cell 10.

[0173] The intermediate interconnect layer is typically selected from transparent materials with high refractive index. An effective intermediate interconnect layer needs high light transmittance to reduce light reflection and absorption at the interconnect layer interface, and good conductivity to reduce the impact of series resistance on device performance. For example, transparent conductive metal oxide thin films (ITO) can be used as intermediate interconnect layers.

[0174] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A solar cell, characterized in that, The solar cell includes a substrate, the substrate including a first surface and a second surface disposed opposite to each other, and the substrate further including a third surface connecting the first surface and the second surface; The first surface includes a first region close to the third surface and a second region far from the third surface. The distance between the first region and the second surface is less than the distance between the second region and the second surface. The connection between the first region and the second region has an inclined angle. The doping concentration in the second region is greater than that in the first region; The first region includes a first texture structure, and the third surface includes a second texture structure. The reflectivity of the first texture structure is less than or equal to the reflectivity of the second texture structure. The width of the first region is 50μm-500μm.

2. The solar cell according to claim 1, characterized in that, The tilt angle is 50°-120°.

3. The solar cell according to claim 1, characterized in that, The distance between the first region and the second surface is D1, and the distance between the second region and the second surface is D2. The difference between D2 and D1 is 1μm-5μm.

4. The solar cell according to any one of claims 1 to 3, characterized in that, The first texture structure is a first pyramid structure, and the height of the first pyramid structure is 1μm-2μm.

5. The solar cell according to claim 4, characterized in that, The second zone is provided with a third pyramid structure, the height of which is 0.8μm-2μm.

6. The solar cell according to claim 5, characterized in that, The reflectivity of the first pyramid structure is 2%-3% lower than that of the third pyramid structure.

7. The solar cell according to any one of claims 1 to 3, characterized in that, The first texture structure is a first tower base structure, and the side length of the first tower base structure is 3μm-30μm.

8. The solar cell according to claim 4, characterized in that, The second texture structure is a second pyramid structure, and the height of the second pyramid structure is 0.5μm-2μm.

9. The solar cell according to claim 7, characterized in that, The second texture structure is a second tower base structure, and the side length of the second tower base structure is 3μm-30μm.

10. A method for preparing a solar cell, used to prepare the solar cell according to any one of claims 1 to 9, characterized in that, The solar cell includes a substrate, the substrate including a first surface and a second surface; A first laser is used to create a groove on the first surface of the substrate, forming a first region and a second region on the first surface. The distance between the first region and the second surface of the substrate is less than the distance between the second region and the second surface of the substrate. The substrate is cut along the first region using a second laser; The substrate is etched to form a first texture structure on the first region and a second texture structure on the cut surface of the substrate.

11. The method for preparing a solar cell according to claim 10, characterized in that, When the first laser creates the groove on the first surface of the substrate, the power of the first laser is 30W-200W, the scanning speed of the first laser is 15m / s-70m / s, the frequency of the first laser is 600KHz-1200KHz, and the spot size of the laser emitted by the first laser is 100um-1000um.

12. The method for preparing a solar cell according to claim 10, characterized in that, When the second laser cuts the substrate along the centerline of the first region, the power of the second laser is 100W-1000W, the scanning speed of the second laser is 15m / s-70m / s, and the spot size of the laser emitted by the second laser is 10um-100um.

13. A stacked battery, characterized in that, The stacked battery includes a top battery, an intermediate connecting layer, and a bottom battery, wherein the intermediate connecting layer connects the top battery and the bottom battery. The top cell is one of a perovskite cell, a cadmium telluride solar cell, a copper indium gallium selenide solar cell, or a gallium arsenide solar cell, and the bottom cell is a solar cell according to any one of claims 1 to 9 or a solar cell prepared by the solar cell preparation method according to any one of claims 10 to 12.

14. A photovoltaic module, characterized in that, The photovoltaic module includes a first cover plate, a first encapsulating film, a battery string, a second encapsulating film, and a second cover plate stacked together. The battery string includes multiple electrically connected solar cells or tandem cells, wherein the solar cells are the solar cells according to any one of claims 1 to 9, or solar cells prepared by the solar cell preparation method according to any one of claims 10 to 12, or the tandem cells are the tandem cells according to claim 13.

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