Solar cell, photovoltaic module, and laminated cell

Abstract

The application relates to the technical field of solar cells, in particular to a solar cell, a photovoltaic module and a laminated cell. The solar cell comprises a substrate and a functional film layer. The first surface of the substrate comprises a first textured area and a second textured area. The second textured area is located in the first textured area, and the second textured area has a closed structure. The heights of the first textured area and the second textured area are different along the thickness direction of the substrate. The junction of the first textured area and the second textured area has a junction groove, and the extension track of the junction groove is a closed structure. In the above manner, the photo-generated carriers generated at any position below the first textured area can quickly enter the collection area in the first textured area, the transmission distance of the photo-generated carriers horizontally transmitted to the collection area is reduced, the recombination probability of the carriers is reduced, and the photoelectric conversion efficiency is improved.

Description

Technical Field

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

[0002] With the accelerated transition from traditional fossil fuels and the increasing demand for sustainable development, solar cells, as a clean and renewable energy technology, are increasingly becoming an important component of the energy system. A solar cell is essentially a semiconductor device that directly converts solar energy into electrical energy. Its working principle is based on the photovoltaic effect: when sunlight shines on the cell, photon energy excites electron-hole pairs (i.e., charge carriers) to be generated inside the semiconductor. These charge carriers then separate under the influence of a built-in electric field, forming a potential difference. By effectively extracting these charge carriers through the metal electrodes on the front and back of the cell, direct current can be generated for use in external circuits, thus achieving the efficient conversion and utilization of solar energy into electrical energy.

[0003] In related technologies, in order to improve the electrical performance of solar cells, the regions of solar cells connected to the electrodes and those not connected to the electrodes are designed differently. However, the problem of high recombination rate still exists, which is not conducive to improving conversion efficiency. Summary of the Invention

[0004] Based on this, this application provides a solar cell, a photovoltaic module, and a tandem cell to solve the technical problems in the prior art that are not conducive to improving conversion efficiency.

[0005] In a first aspect, embodiments of this application provide a solar cell, comprising: A substrate having a first surface and a second surface disposed opposite to each other along the thickness direction; the first surface and the second surface are a front surface and a rear surface, respectively. A functional film layer, including a passivation film layer and an antireflection film layer, wherein the functional film layer covers the first surface and the second surface of the substrate; The first surface includes at least one first texture area and at least one second texture area; the first texture area includes multiple first pyramid structures, and the second texture area includes multiple second pyramid structures; the average height of the upper surface of the first texture area is different from the average height of the upper surface of the second texture area, and there is a height difference ΔH between them; A boundary groove is provided between the first texture area and the second texture area; with the first surface of the substrate as the reference surface, the bottom depth of the boundary groove is d, and d≥ΔH is satisfied; Furthermore, the boundary groove is a continuous or discontinuous ring shape, and the boundary groove encloses and surrounds the second texture area.

[0006] Secondly, embodiments of this application provide a stacked battery, comprising: Top cell, which can be a perovskite cell, cadmium telluride solar cell, copper indium gallium selenide solar cell, or gallium arsenide solar cell; Intermediate connecting layer; and The bottom battery is the aforementioned solar cell; The top battery, the intermediate connecting layer, and the bottom battery are stacked and connected.

[0007] Thirdly, embodiments of this application provide a photovoltaic module, including the aforementioned solar cell or the aforementioned tandem cell.

[0008] In the solar cell of this application embodiment, the second textured region has a closed structure, and at least one second textured region is located within the first textured region. Through the cooperation of the first and second textured regions, the first textured region is divided into multiple sub-regions by multiple second textured regions, reducing the area of ​​a single first textured region sub-region. Photogenerated carriers generated at any position in the first textured region sub-region can quickly enter the collection region within that sub-region, greatly reducing the transmission distance of photogenerated carriers laterally to the collection region, reducing the recombination probability of carriers, and thus improving photoelectric conversion efficiency. The boundary groove has a scattering effect on light incident on the inner wall surface of the boundary groove, which can change the propagation path of light inside the solar cell, increase the effective optical path of light inside the solar cell, and improve the absorption of long-wavelength light to increase photocurrent. The boundary groove can separate the first textured region and the second textured region, and the existence of the height difference between the first and second textured regions can reduce the probability that photogenerated carriers generated at any position in the first textured region will cross the boundary groove to enter the second textured region, reducing the recombination rate of carriers and thus improving photoelectric conversion efficiency. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the structure of a solar cell according to an embodiment of this application.

[0010] Figure 2 for Figure 1 The diagram shows a partial structural schematic of a solar cell.

[0011] Figure 3 This is a scanning electron microscope image of a solar cell according to an embodiment of this application.

[0012] Figure 4 This is another scanning electron microscope image of a solar cell according to an embodiment of this application.

[0013] Figure 5 This is another scanning electron microscope image of a solar cell according to an embodiment of this application.

[0014] Figure 6This is a schematic diagram of the structure of the first protrusion and the second protrusion in the solar cell of this application embodiment, wherein (a) is a cone-like protrusion, (b) is a dune-like protrusion, (c) is a pyramid-like protrusion, (d) is a spherical protrusion, (e) is a pyramid, and (f) is a perspective structure of the first pyramid structure covered by the first functional film layer.

[0015] Figure 7 This is a schematic diagram of the structure at the junction of the first textured region and the second textured region in a solar cell according to an embodiment of this application.

[0016] Figure 8 This is another structural schematic diagram of a solar cell according to an embodiment of this application.

[0017] Figure 9 This is another structural schematic diagram of a solar cell according to an embodiment of this application.

[0018] Figure 10 This is a schematic diagram of a first distribution structure of the first textured region and the second textured region in a solar cell according to an embodiment of this application.

[0019] Figure 11 This is a schematic diagram of a second distribution structure of the first textured region and the second textured region in a solar cell according to an embodiment of this application.

[0020] Figure 12 This is another scanning electron microscope image of a solar cell according to an embodiment of this application.

[0021] Figure 13 This is a schematic diagram of the structure of a solar cell according to an embodiment of this application.

[0022] Figure 14 This is a schematic diagram of the structure of the battery string in the photovoltaic module according to an embodiment of this application.

[0023] Figure 15 This is a schematic diagram of the structure of a photovoltaic module according to an embodiment of this application.

[0024] Figure 16 This is a schematic diagram of the structure of the solar cell in Comparative Example 2.

[0025] Reference numerals: 100-Solar cell; 11-Substrate; 11a-First surface; 11b-Second surface; 12-Functional film layer; 120-First passivation layer; 13-First textured region; 14-Second textured region; 15-Boundary groove; 151-First sidewall; 152-Second sidewall; 153-Middle bottom; 1511-First side surface; 1521-Second side surface; 154-Opening; 1512-First side ridge; 1522-Second side ridge; 1523-Third side ridge; 150-Rhomboid structure; 15a-First boundary groove segment; 15b-Second boundary groove segment; 1321-First pyramid structure; 1322-First functional film layer; 131-Emitter; 16-First trace groove; 17-First antireflection layer; 181-First electrode; 182-Second electrode; 191-Tunneling oxide layer; 192-Doped polycrystalline silicon layer; 193-Back passivation layer; 194-Second antireflection layer; 200-Photovoltaic module; 201-Battery string; 202-Encapsulating film; 203-Cover plate; 20-Solder ribbon. Detailed Implementation

[0026] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0027] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0029] like Figures 1 to 12 As shown, this is a solar cell 100 provided in an embodiment of this application.

[0030] like Figure 1 and Figure 11As shown, the solar cell 100 of this application embodiment includes a substrate 11 and a functional film layer 12 covering the substrate 11. The substrate 11 has a first surface 11a and a second surface 11b disposed opposite to each other along its thickness direction. The functional film layer 12 covers the first surface 11a and the second surface 11b of the substrate 11. The functional film layer 12 includes a passivation film layer covering the substrate 11 and an anti-reflection film layer covering the passivation film layer.

[0031] The first surface 11a includes at least one first textured area 13 and at least one second textured area 14. The first textured area 13 contains multiple first pyramid structures, and the second textured area 14 contains multiple second pyramid structures. The average height of the upper surface of the first textured area 13 is different from the average height of the upper surface of the second textured area 14, and there is a height difference ΔH between them.

[0032] like Figure 2 As shown, in the thickness direction of the substrate 11, the height of the upper surface of the first texture area 13 can be the distance H1 between the top of the first pyramid structure and the first face 11a in the first texture area 13, the height of the upper surface of the second texture area 14 can be the distance H2 between the top of the second pyramid structure and the first face 11a in the second texture area 14, the average height of the upper surface of the first texture area 13 can be the average value of the distance H1 between the top of the first pyramid structure and the first face 11a, and the average height of the upper surface of the second texture area 14 can be the average value of the distance H2 between the top of the second pyramid structure and the first face 11a.

[0033] like Figure 2 As shown, a boundary groove 15 is provided between the first texture area 13 and the second texture area 14; with the first surface 11a of the base 11 as the reference surface, the bottom depth of the boundary groove 15 is d, and d≥ΔH is satisfied.

[0034] And, please see Figure 10 and Figure 11 As shown, the boundary groove 15 is a continuous or discontinuous ring shape, and the boundary groove 15 encloses and surrounds the second textured area 14. That is, if all areas of the first textured area 13 are considered as a whole, then at least one second textured area 14 is located in the first textured area 13, and the second textured area 14 has a closed structure. Because there is a height difference ΔH between the average height of the upper surface of the first textured area 13 and the average height of the upper surface of the second textured area 14, that is, along the thickness direction of the substrate 11, the heights of the first textured area 13 and the second textured area 14 are different. Figures 2 to 4 as well as Figures 10 to 11 As shown, each adjacent area of ​​the first texture area 13 and the second texture area 14 is provided with a boundary groove 15, which is a groove-shaped structure formed at the physical boundary between the first texture area 13 and the second texture area 14.

[0035] The second texture region 14 is a closed region. The first texture region 13 is divided into multiple sub-regions by multiple second texture regions 14, which reduces the area of ​​a single sub-region of the first texture region 13. Photogenerated carriers generated at any position in the sub-region of the first texture region 13 can quickly enter the collection region within that sub-region, greatly reducing the transmission distance of photogenerated carriers to the collection region laterally, reducing the recombination probability of carriers, and thus improving photoelectric conversion efficiency.

[0036] Without the junction groove 15, the first textured area 13 and the second textured area 14 would form a direct planar joint. In this case, the effective mechanical contact between the first textured area 13 and the second textured area 14 would be limited to line contact or a strip-like contact of limited width at the joint, with an area only equal to the projected area of ​​the joint. This limited contact form would result in low interface stress transfer efficiency. When external loads (such as tension, shear, or bending moment) are applied to the joint structure, due to the limited contact area, the load transfer path is restricted to a narrow contact range and cannot be diffused and dissipated through a wider material volume. This would cause significant stress concentration at the joint edge, i.e., at the interface where the material stiffness changes abruptly. The stress peak at the joint edge is very likely to exceed the bond strength (including tensile strength and shear strength) at the interface where the stiffness changes abruptly, thus causing cracking at the joint between the first textured area 13 and the second textured area 14. Furthermore, this simple planar splicing interface mainly relies on interfacial normal stress and shear stress to transfer loads. Since the bonding strength of the interface is usually much lower than the strength of the material itself, and this load transfer mode is singular, it is difficult to redistribute and reduce stress through multiaxial stress states or more complex mechanical paths.

[0037] Therefore, as a geometric transition design, this interface groove can effectively coordinate the deformation between different texture areas, reduce stress concentration caused by local stiffness differences, and thus optimize the overall strain distribution.

[0038] With the cooperation of the first textured region 13 and the second textured region 14, photogenerated carriers generated at any position below the first textured region 13 can quickly enter the collection area within the first textured region 13, reducing the transmission distance of photogenerated carriers to the collection area laterally, reducing the recombination probability of carriers, and thus improving photoelectric conversion efficiency.

[0039] The first textured region 13 and the second textured region 14 have different heights. Before photogenerated carriers are collected, lateral diffusion is suppressed, and they are more likely to be rapidly extracted by the longitudinal electric field, reducing lateral recombination. For example, along the thickness direction of the substrate 11, the top height of the first textured region 13 and the top height of the second textured region 14 are different, or the top height of the first textured region 13 and the top height of the second textured region 14 are different, and the bottom height of the first textured region 13 and the bottom height of the second textured region 14 are different.

[0040] The boundary groove 15 can separate the first texture region 13 and the second texture region 14, which can reduce the probability that photogenerated carriers generated at any position below the first texture region 13 will cross the boundary groove 15 and enter the second texture region 14, thereby reducing the recombination probability of carriers and improving photoelectric conversion efficiency.

[0041] Furthermore, due to the presence of the junction groove 15, the functional film layer 12 can be deposited better at the junction of the first textured region 13 and the second textured region 14, thereby improving the formation quality of the functional film layer 12 at the junction of the first textured region 13 and the second textured region 14, which in turn improves the passivation effect of the functional film layer 12 on the substrate 11. At the same time, it also helps to reduce the contact resistance between the functional film layer 12 and the subsequently deposited conductive material, thereby reducing transmission loss.

[0042] In one implementation, the doping concentration of the second texture region 14 is lower than that of the first texture region 13.

[0043] The doping concentration of the second textured region 14 is lower than that of the first textured region 13. A strong PN junction electric field cannot be formed in the second textured region 14 and below it, which increases the passivation effect of the second textured region 14 and reduces the recombination probability of charge carriers in and below it, thus improving photoelectric conversion efficiency. Through the cooperation of the first textured region 13 and the second textured region 14, both low contact resistance and low surface recombination are achieved. Specifically, the higher doping concentration of the first textured region 13 compared to the second textured region 14 relatively reduces the sheet resistance of the first textured region 13 and relatively increases the sheet resistance of the second textured region 14, further enhancing the carrier collection efficiency of the first textured region 13 and further enhancing the passivation effect of the second textured region 14.

[0044] The first texture area 13 has a first texture structure, which includes multiple first pyramid structures. The second texture area 14 has a second texture structure, which includes multiple second pyramid structures. The thickness of the first texture area 13 is the height of the first texture structure along the thickness direction of the base 11, and the thickness of the second texture area 14 is the height of the second texture structure along the thickness direction of the base 11.

[0045] In one implementation, there is no emitter below the second textured region 14. Specifically, the area below the second textured region 14 is the substrate 11 located below the second textured region 14 in the thickness direction of the substrate 11, such as... Figure 13 As shown at point A in the middle.

[0046] In this embodiment, there is no emitter below the second textured region 14, and a strong PN junction electric field cannot be formed below the second textured region 14. This can further increase the passivation effect of the second textured region 14, reduce the recombination probability of charge carriers in and below the second textured region 14, and help improve the photoelectric conversion efficiency.

[0047] In one implementation, the substrate 11 is doped with a first conductivity type, while the second textured region 14 may not be doped with a second conductivity type. That is, the second pyramidal microstructure in the second textured structure does not have a second conductivity type doping, and the first and second conductivity types are opposite. For example, the first conductivity type is N-type and the second conductivity type is P-type, or vice versa. In this case, the second textured region 14 has no emitter, and there is no emitter below the second textured region 14. A PN junction electric field cannot be formed in the second textured region 14 and below it, which increases the passivation effect of the second textured region 14 and reduces the recombination probability of charge carriers in and below the second textured region 14, thus improving photoelectric conversion efficiency.

[0048] In another implementation, the second texture region 14 may have very shallow doping of the second conductivity type, that is, the second texture structure may have very shallow doping of the second conductivity type, and the doping concentration of the second conductivity type element in the second texture region 14 is less than or equal to 5E17. That is, the doping concentration of the second conductivity type element in the second pyramid microstructure is less than or equal to 5E17. At this point, the second textured region 14 cannot form a strong PN junction electric field, but it can effectively form field-effect passivation and suppress Auger recombination. Specifically, the first textured region 13 and the second textured region 14 have more defects and are prone to recombination. The main purpose of doping the second textured region 14 is not to form a PN junction, but to form a fixed charge layer on the surface of the second textured region 14, and to form an electric field on the first surface of the substrate 11 to prevent photogenerated carriers (e.g., minority carriers) from reaching the surface of the substrate 11 and reduce the recombination probability.

[0049] In some embodiments, the second textured structure may have very shallow doping of the second conductivity type, and the doping concentration of the second conductivity type element in the second textured region 14 is less than or equal to 5E17. There is no doping of the second conductivity type element below the second texture region 14, and there is no emitter below the second texture region 14. At this time, a PN junction electric field cannot be formed below the second texture region 14, and the second texture region 14 can effectively form field-effect passivation to suppress Auger recombination.

[0050] In one implementation, the doping concentration of the second conductivity type element in the first texture region 13 can be 5E17. ~1E21 .

[0051] In this embodiment, the doping concentration of the second conductivity type element in the first texture region 13 is controlled within the above range, which can reduce the contact resistance and improve the fill factor.

[0052] As one implementation method, please refer to Figure 2 and Figure 4 As shown, the boundary groove 15 includes a first sidewall 151, a second sidewall 152, a central bottom 153, and an opening 154. The central bottom 153 is the bottom of the boundary groove 15. The first sidewall 151 is the side of the first textured area 13 facing the second textured area 14, and the second sidewall 152 is the side of the second textured area 14 facing the first textured area 13. The central bottom 153 is disposed on the first surface 11a of the substrate 11 and is connected to the first sidewall 151 and the second sidewall 152. The opening 154 is defined by the end of the first sidewall 151 away from the central bottom 153 and the end of the second sidewall 152 away from the central bottom 153. The central bottom 153 and the opening 154 are opposite each other in the thickness direction of the substrate 11. The first sidewall 151, the second sidewall 152, the central bottom 153, and the opening 154 together form the boundary groove 15.

[0053] Furthermore, due to the presence of the boundary groove 15 between adjacent first textured regions 13 and second textured regions 14, when light is incident into the boundary groove 15, the inner wall of the boundary groove 15 has a scattering effect on the light, which can change the propagation path of the light inside the solar cell 100, increase the effective optical path of the light inside the solar cell 100, improve the absorption of long-wavelength light, and help increase the photocurrent. In other words, the groove-shaped boundary groove 15 has a certain light-trapping effect.

[0054] It is understood that the boundary groove 15 can be partially set in the adjacent area of ​​the first texture area 13 and the second texture area 14. In addition to the first sidewall 151, the second sidewall 152, the middle bottom 153 and the opening 154, the boundary groove 15 further includes a third sidewall and a fourth sidewall that are arranged opposite to each other in its extension direction. The third sidewall is connected to the middle bottom 153, the first sidewall 151 and the second sidewall 152 respectively, and the fourth sidewall is connected to the middle bottom 153, the first sidewall 151 and the second sidewall 152 respectively. At this time, the opening 154 is defined by the end of the first sidewall 151 away from the middle bottom 153, the end of the second sidewall 152 away from the middle bottom 153, the end of the third sidewall away from the middle bottom 153 and the end of the fourth sidewall away from the middle bottom 153. That is, the first sidewall 151, the second sidewall 152, the third sidewall, the fourth sidewall, the middle bottom 153 and the opening 154 together form the boundary groove 15.

[0055] In this embodiment, the boundary groove 15 can be set in a part of the adjacent area of ​​the first textured area 13 and the second textured area 14, which can improve the flexibility of the boundary groove setting. The boundary groove 15 can be set at the stress concentration point, without needing to be in a part of the adjacent area of ​​the first textured area 13 and the second textured area 14, thereby reducing the manufacturing difficulty of the solar cell.

[0056] In some implementations, please refer to Figure 12 As shown, taking the boundary groove segment extending along the second direction in the boundary groove 15 as an example, the first sidewall 151 and the second sidewall 152 are arranged opposite to each other in the first direction. The boundary groove 15 (boundary groove segment) extends along the second direction, which is perpendicular to the first direction. The first and second directions are parallel to the first surface 11a, respectively. The boundary groove 15 meanders along the second direction on the first surface 11a. The width W1 of the boundary groove 15 in the first direction is less than or equal to 1000 μm.

[0057] In this embodiment, the meandering extension of the boundary groove further increases the contact area between the first texture area 13 and the second texture area 14, which can effectively coordinate the deformation between different texture areas and further alleviate the stress concentration problem caused by local stiffness differences.

[0058] Those skilled in the art will understand that the boundary trench segment in the boundary trench 15 can also extend in other directions, for example, as Figure 11 As shown, the boundary trench segment can also extend along the first direction, and the boundary trench segments extending in other directions are... Figure 12 The structures shown are similar, and will not be described in detail here.

[0059] In some embodiments, the extension trajectory of the boundary groove 15 includes a broken line extension segment, wherein the included angle between two adjacent broken lines in the broken line extension segment is 90° to 108°.

[0060] In this embodiment, the zigzag extension section significantly increases the length of the force transmission path and uses its curved shape to guide the force flow around the stress concentration point, thereby reducing the stress peak and effectively preventing cracks from propagating in a straight line.

[0061] In some embodiments, the extension trajectory of the junction groove 15 includes a curved extension segment, wherein the curvature of any curve in the curved extension segment is 0 to 0.001 m. -1 .

[0062] In this embodiment, the curved extension section smoothly decomposes the unidirectional principal stress into multi-directional components through continuous curvature changes, achieving uniform stress distribution. The crack propagation path is forced to deflect continuously, resulting in greater energy consumption and effectively delaying crack propagation.

[0063] In some embodiments, the extension trajectory of the boundary groove 15 includes a polygonal extension segment and a curved extension segment, wherein the included angle between two adjacent polygonal lines in the polygonal extension segment is 90° to 108°, and the curvature of any curve in the curved extension segment is 0 to 0.001m. -1 .

[0064] In this embodiment, the force flow distribution is dominated by the broken line segment, and the stress transition is achieved by the curved segment. This can take into account both directional guidance and stress homogenization, which can not only effectively reduce the peak stress, but also obtain the smoothest stress distribution. Due to the relatively complex crack propagation path, it can consume crack energy to a large extent, which is beneficial to improving fatigue resistance.

[0065] As one implementation method, please refer to Figure 4 As shown, the sidewall of the junction groove 15 has a prismatic structure 150.

[0066] In this embodiment, the prismatic structure on the sidewall of the junction groove 15 can further enhance the optical light trapping effect of the junction groove 15, further enhance the scattering effect of light incident on the sidewall of the junction groove 15, change the propagation path of light inside the solar cell, increase the effective optical path of light inside the solar cell, and improve the absorption of long-wavelength light to increase the photocurrent.

[0067] Those skilled in the art should understand that if the first textured area and the second textured area also include other protruding structures besides the pyramid structure, the sidewalls of the junction groove 15 may also have pleated structures, multi-curved surface structures, or irregular protruding structures. The pleated structures, multi-curved surface structures, or irregular protruding structures on the sidewalls of the junction groove 15 can further enhance the optical light-trapping effect of the junction groove 15.

[0068] In some implementations, please refer to [the relevant documentation]. Figure 3 As shown, the boundary groove 15 includes a first sidewall 151 and a second sidewall 152. The first textured area 13 has a first pyramid structure, and the first pyramid structures located at the boundary are arranged on the side facing the second textured area 14 to form the first sidewall 151 of the boundary groove 15. The second textured area 14 has a second pyramid structure, and the second pyramid structures located at the boundary are arranged on the side facing the first textured area 13 to form the second sidewall 152 of the boundary groove 15.

[0069] Specifically, multiple first pyramid structures are arranged along the extension direction of the boundary groove 15 at the junction, and the sides of these multiple first pyramid structures facing the second texture region 14 are continuously connected to form a first sidewall 151; multiple second pyramid structures are arranged along the extension direction of the boundary groove 15 at the junction, and the sides of these multiple second pyramid structures facing the first texture region 13 are continuously connected to form a second sidewall 152; the boundary groove 15 is naturally enclosed by the sides of the microstructure units of the first texture region 13 and the second texture region 14, which can effectively block the lateral diffusion of photogenerated carriers, improve the collection efficiency of carriers, and reduce the recombination probability of carriers.

[0070] Those skilled in the art will understand that the bottom of the junction groove 15, i.e., the middle bottom 153 of the junction groove 15, is undulating in the thickness direction of the substrate 11, and the bottoms of the junction groove 15 may not be at the same height. The undulating bottom can reduce the reflectivity of light, further increasing the light-trapping effect of the junction groove, thereby improving the conversion efficiency. For example, in the thickness direction of the substrate 11, the distance between the bottom of the junction groove 15 and the first surface 11a can be 0.5 μm to 10 μm.

[0071] Those skilled in the art will understand that in other embodiments, if the first textured area and the second textured area further include other protruding structures besides the pyramid microstructure, for example, the first textured area includes a first protrusion and the second textured area includes a second protrusion, specifically, multiple first protrusions at the junction are arranged along the extending direction of the junction groove 15, and these multiple first protrusions are continuously connected to the side facing the second textured area 14, together forming a first sidewall 151; multiple second protrusions at the junction are arranged along the extending direction of the junction groove 15, and these multiple second protrusions are continuously connected to the side facing the first textured area 13, together forming a second sidewall 152; please refer to Figure 6 As shown, the first protrusion includes at least one of a conical protrusion, a dune protrusion, a pyramidal protrusion, a spherical protrusion, or a pyramid. The side of the first protrusion facing the second texture area 14 includes at least one of a convex curved surface, a concave curved surface, an inclined tower surface, a partially spherical surface, or a triangular tower surface.

[0072] The second protrusion includes at least one of a conical protrusion, a dune protrusion, a pyramidal protrusion, a spherical protrusion, or a pyramid, and the side of the second protrusion facing the first texture area includes at least one of a convex curved surface, a concave curved surface, an inclined tower surface, a partially spherical surface, or a triangular tower surface.

[0073] In this embodiment, the texture structure in the first texture region 13 and the texture structure in the second texture region 14 are highly consistent. During the deposition of the passivation layer in the functional film layer 12, when the passivation layer deposition gas flows to the top of the first surface of the substrate 11, the gas flow rate can be more uniformly distributed. The passivation layer can undulate with the surface undulations of the first texture region 13 and the second texture region 14, thereby improving the formation quality of the passivation layer on the first surface of the substrate 11 and thus improving the passivation effect of the substrate 11.

[0074] In some embodiments, the junction groove 15 is perpendicular to its extending direction (e.g., Figure 3 The cross-section of the groove 15 (shown in the second direction) is V-shaped, U-shaped, asymmetrical V-shaped, or asymmetrical U-shaped. Specifically, the bottom of the first sidewall 151 and the bottom of the second sidewall 152 of the V-shaped or asymmetrical V-shaped junction groove 15 are directly connected, and the middle bottom 153 is formed by the intersection of the first sidewall 151 and the second sidewall 152.

[0075] In this embodiment, the V-shaped or asymmetrical V-shaped junction groove 15 can further enhance the light trapping effect, especially for oblique light with a large angle.

[0076] In some embodiments, the cross-section of the junction groove 15 perpendicular to its extension direction is U-shaped or asymmetrical U-shaped.

[0077] In this embodiment, the U-shaped or asymmetrical U-shaped junction groove 15 makes it easier to achieve continuous, uniform, and pore-free coverage of the subsequently deposited passivation layer and antireflection film.

[0078] In some embodiments, on a cross section of the junction groove 15 perpendicular to its extension direction, the included angle between the first sidewall 151 and the second sidewall 152 is greater than or equal to 30° and less than 180°.

[0079] In this embodiment, the first sidewall 151 and the second sidewall 152 each have a certain inclination angle, which can effectively scatter and reflect light. For example, long-wavelength light from the second textured region 14 can be guided to the first textured region 13, enhancing the light-trapping effect. Controlling the included angle between the first sidewall 151 and the second sidewall 152 within the above-mentioned range, avoiding an excessively large or small angle, can effectively disperse stress, prevent stress concentration, and improve crack resistance; the inclined sidewalls provide multiple reflection opportunities, enhancing light absorption.

[0080] In one embodiment, the height difference ΔH between the average height of the upper surface of the first textured region 13 and the average height of the upper surface of the second textured region 14 is 0.1 nm to 10 μm. That is, in the thickness direction of the substrate 11, the difference between the height of the first textured region 13 and the height of the second textured region 14 is 0.1 nm to 10 μm.

[0081] Please see Figure 8 and Figure 9 As shown, the heights of the first textured area 13 and the second textured area 14 are different along the thickness direction of the substrate 11. For example, the top height of the first textured area 13 and the top height of the second textured area 14 are different along the thickness direction of the substrate 11, or the top height of the first textured area 13 and the top height of the second textured area 14 are different and the bottom height of the first textured area 13 and the bottom height of the second textured area 14 are different.

[0082] In this embodiment, due to the height difference between the first texture region and the second texture region, the lateral diffusion of photogenerated carriers is suppressed before they are collected, and they are more likely to be rapidly extracted by the longitudinal electric field, thus reducing lateral recombination.

[0083] For example, in the thickness direction of the substrate 11, the thickness of the first textured region 13 is 0.5 μm to 10 μm, and the thickness of the second textured region 14 is 0.5 μm to 10 μm.

[0084] In some embodiments, the height of the first pyramid structure is greater than the height of the second pyramid structure in the thickness direction of the base 11. Specifically, in the thickness direction of the base 11, the bottom of the first textured area 13 and the bottom of the second textured area 14 may be at the same height, and the height difference between the first textured area 13 and the second textured area 14 is due to the difference in height between the first pyramid structure and the second pyramid structure.

[0085] In this embodiment, photons incident on the lower second pyramid structure are more easily guided to the adjacent higher first pyramid structure after being scattered or reflected by its surface and the sidewalls of the junction groove, thus improving the effective utilization rate of photons.

[0086] In some implementations, please refer to Figure 9 As shown, in the thickness direction of the substrate 11, the bottom of the first textured area 13 is higher than the bottom of the second textured area 14.

[0087] In this embodiment, because the bottom of the second textured region 14 is lower, the second textured region 14 is constructed as a recessed region surrounded by the raised first textured region 13. Light incident or reflected into the second textured region 14, when extending upwards or laterally, is highly likely to be reflected or scattered by the first sidewall 151 formed by the first pyramid structure. This increases the chance of light contacting the first textured region 13 before escaping, enhancing the light-trapping effect of the second textured region 14, especially effectively capturing large-angle incident light and long-wavelength light, significantly improving the short-circuit current. On the other hand, the lower bottom of the second textured region 14 effectively blocks the lateral diffusion path of photogenerated carriers from the first textured region 13 to the second textured region 14. The photogenerated carriers are physically held within the higher first textured region 13 and can only be efficiently collected by the vertical PN junction electric field, greatly reducing surface recombination. In this embodiment, please refer to... Figure 7 As shown, the first pyramid structure at the junction has at least one first side 1511 facing the second texture area 14, and the second pyramid structure at the junction has at least one second side 1521 facing the first texture area 13. The first sidewall 151 of the junction groove 15 is formed by the first sidewall 1511 of the first pyramid structure at the junction in sequence, and the second sidewall 152 of the junction groove 15 is formed by the second sidewall 1521 of the second pyramid structure at the junction in sequence.

[0088] In some implementations, please refer to Figure 6 As shown in (f), a first pyramid structure and a first functional membrane layer covering the first pyramid structure form a first composite protrusion, and correspondingly, a second pyramid structure and a first functional membrane layer covering the second pyramid structure form a second composite protrusion. Exemplarily, the first composite protrusion includes at least one of a conical protrusion, a dune-like protrusion, a pyramid-like protrusion, or a spherical protrusion, and the second composite protrusion includes at least one of a conical protrusion, a dune-like protrusion, a pyramid-like protrusion, or a spherical protrusion. For example, please refer to [link to example]. Figure 6 As shown in (f), the first composite protrusion includes a first pyramid structure 1321 and a first functional membrane layer 1322 covering the first pyramid structure 1321. The coverage of the first functional membrane layer 1322 makes the first composite protrusion more rounded than the first pyramid structure 1321.

[0089] In some embodiments, the height of the first pyramid structure is 0.5–10 μm, and the height of the second pyramid structure is 0.5–10 μm. Further, the height of the first pyramid structure is 0.5–5 μm, and the height of the second pyramid structure is 0.5–5 μm.

[0090] In this embodiment, controlling the height dimensions of the first pyramid structure and the second pyramid structure within the aforementioned ranges helps to balance the light-trapping effects of the first and second textured regions, making it easier for light to be guided to the first textured region. Furthermore, controlling the height dimensions of the first and second pyramid structures within the aforementioned ranges improves the dimensional uniformity of the textured structures in different regions on the first surface of the substrate 11. This improves the formation quality of the passivation layer in the functional film layer 12 on the first surface of the substrate 11, enhances the morphological consistency of the passivation layer on the first surface of the substrate 11, and improves the passivation effect of the passivation layer.

[0091] In some embodiments, the apex of the first pyramid structure is higher than the apex of the second pyramid structure in the thickness direction of the substrate 11. Specifically, in the thickness direction of the substrate 11, the bottom of the first textured region 13 and the bottom of the second textured region 14 may be at the same height, and the height difference between the first textured region 13 and the second textured region 14 is due to the difference in height between the first pyramid structure and the second pyramid structure. For example, the height difference between the apex of the first pyramid structure and the apex of the second pyramid structure is 0.1 nm to 10 μm.

[0092] In this embodiment, the second textured area and the first textured area are not only separated by a meandering boundary groove on the plane, but also form a clear height difference in the vertical direction. The boundary groove and its sidewalls between the two are naturally spliced ​​together by the sides of two pyramids of different heights. The boundary groove also serves as a light guiding structure and a photogenerated carrier boundary groove.

[0093] In some implementations, please refer to Figure 7 As shown, the side length of the first side edge 1512 of the first pyramid facing the second texture area 14 is greater than the side length of the second side edge 1522 of the second pyramid facing the first texture area 13.

[0094] In this embodiment, the first sidewall 151 of the junction groove 15 has a relatively wider slope than the second sidewall 152, which can efficiently reflect light rays scattered from the second texture area or emitted from itself back to the depth of the first texture area or to the second texture area at a smaller angle, thereby increasing the optical path.

[0095] In some embodiments, the side length of the first side edge of the first pyramid structure facing the second textured area 14 is 1.64 μm to 3.44 μm.

[0096] In some implementations, such as Figure 7 As shown, the first side edge 1512 of the first pyramid structure facing the second texture area 14 is parallel to the third side edge 1523 of the second pyramid structure facing away from the first texture area 13.

[0097] In this embodiment, the side edges of the first pyramid structure and the second pyramid structure facing the same side are parallel. The relatively orderly arrangement allows light to be reflected multiple times and in a coordinated manner in the first texture area, the second texture area and the boundary groove, rather than being scattered randomly. This improves the efficiency of guiding light from the second texture area to the first texture area, reduces photon escape, and achieves a high light trapping efficiency.

[0098] In some implementations, such as Figure 10 As shown, along the first direction, multiple first texture areas 13 and multiple second texture areas 14 are arranged alternately.

[0099] In this embodiment, the first textured region 13 and the second textured region 14 are arranged alternately, making the sheet resistance distribution on the first surface of the substrate 11 more uniform. Furthermore, the more uniform arrangement of the first textured region 13 and the second textured region 14 can further improve the formation quality of the functional film layer 12 on the first surface of the substrate 11, thereby further improving the morphological consistency of the functional film layer 12 on the first surface of the substrate 11, which is beneficial to further improving the passivation effect of the functional film layer 12.

[0100] In some embodiments, the ratio of the length of the first textured region 13 along the first direction to the length of the second textured region 14 along the first direction is 0.3 to 3. For example, the first direction may be parallel to the extension direction of the main gate line, and the second direction may be perpendicular to the extension direction of the main gate line.

[0101] In this embodiment, by controlling the length ratio of the first textured area 13 and the second textured area 14 along the first direction within the above-mentioned range, the area of ​​the first textured area 13 and the second textured area can be precisely controlled, which is beneficial to balancing the area ratio of different functional areas on the surface of the solar cell.

[0102] In some embodiments, the boundary groove 15 includes a first boundary groove segment 15a extending along a second direction. The projection of the bottom of the first boundary groove segment 15a onto the first surface is a polygonal, curved, or sawtooth shape. The second direction is perpendicular to the first direction, and the first direction and the second direction are parallel to the first surface 11a, respectively.

[0103] In this embodiment, the first texture area 13 and the second texture area 14 are arranged alternately along the first direction, and the first boundary groove segment 15a extends along the second direction and also extends in a meandering manner.

[0104] In some implementations, please refer to Figure 11 As shown, several second texture areas 14 are arrayed within the first texture area 13.

[0105] In this embodiment, multiple second textured regions 14 are relatively evenly distributed within the first textured region 13. The first textured region 13 is divided into multiple sub-regions by the multiple second textured regions 14, further reducing the area of ​​a single sub-region of the first textured region 13. Photogenerated carriers generated at any position within a sub-region of the first textured region 13 can quickly enter the collection region within that sub-region, greatly reducing the transmission distance of photogenerated carriers laterally to the collection region, lowering the recombination probability of carriers, and thus improving photoelectric conversion efficiency. Furthermore, the more uniform distribution of the first textured region 13 and the second textured region 14 can further improve the formation quality of the functional film layer 12 on the first surface of the substrate 11, thereby further improving the morphological consistency of the functional film layer 12 on the first surface of the substrate 11, which is beneficial for further improving the passivation effect of the functional film layer 12.

[0106] In related technologies, if the first textured region 13 and the second textured region 14 are disposed on at least one side connecting the first surface 11a and the second surface 11b, the contribution of the multi-textured region arrangement on the side to the overall light absorption is limited because the side is not directly exposed to light. Furthermore, since the side is not a major carrier generation and collection area, the effect of multi-textured regionalization on optimizing photoelectric conversion efficiency is limited. Achieving uniform and controllable texture processing on steep sides can increase the difficulty of the process and even lead to defects. Therefore, disposing the first textured region 13 and the second textured region 14 on the side cannot reduce the recombination rate, optimize the light trapping effect, or improve the stress effect.

[0107] For example, during the fabrication of the solar cell 100, the first surface 11a of the substrate 11 can be texturized to form a first textured region 13 on the first surface 11a of the substrate 11; the first surface 11a of the substrate 11 can be doped to form an initial emitter layer, and the corresponding positions of each second textured region 14 on the first surface 11a of the substrate 11 are initial second textured regions; then each initial second textured region on the first surface 11a of the substrate 11 is irradiated with a laser, and then each initial second textured region after laser irradiation is subjected to alkaline etching, the initial emitter layer on the initial second textured region is destroyed, and a recessed structure is formed in the initial second textured region through laser irradiation and alkaline etching, and at least a portion of the initial emitter layer thickness of the initial second textured region is removed; subsequently, the initial second textured region is texturized to form a second textured region 14. The thickness of the initial emitter layer in the initial second texture region damaged by laser irradiation varies, which leads to different doping concentrations of the second conductivity type elements in the second texture region. The greater the thickness of the initial emitter layer in the initial second texture region, the lower the doping concentration of the second conductivity type elements in the second texture region. If the initial emitter layer in the initial second texture region is completely destroyed, then the second texture region has no emitter.

[0108] In some embodiments, the ratio of the area of ​​the second texture region 14 to the area of ​​the first texture region 13 is 0.2 to 5.

[0109] In this embodiment, by controlling the ratio of the area of ​​the second textured region 14 to the area of ​​the first textured region 13 within the above-mentioned range, the areas of the first textured region 13 and the second textured region can be precisely controlled, which is beneficial to balancing the area ratio of different functional areas on the surface of the solar cell.

[0110] In some embodiments, the second texture area 14 is polygonal in shape, and the boundary groove 15 includes a plurality of second boundary groove segments 15b, which correspond to a plurality of sides of the second texture area 14 respectively. The projection of the bottom of the second boundary groove segment 15b on the first surface 11a is a polygonal, curved or sawtooth shape.

[0111] In this embodiment, the second texture area 14 is polygonal, and the shape of the second texture area 14 can be determined according to actual needs to reduce the manufacturing difficulty of the second texture area 14; the second boundary groove segment 15b extends in a meandering manner, and the projection of its bottom on the first surface 11a is a broken line, a curve, or a sawtooth shape, which improves the flexibility of the structure to a certain extent and helps to reduce the manufacturing difficulty of the second texture area 14.

[0112] In some implementations, the second textured area 14 is rectangular in shape.

[0113] In this embodiment, the shape of the second texture area 14 is more regular, which makes the texture morphology on the first surface of the substrate 11 more orderly.

[0114] In some embodiments, the density of the first pyramid structure differs from the density of the second pyramid structure. For example, the density of the first pyramid structure is 300,000 to 360,000. The density of the second pyramid structure is 300,000 to 360,000. .

[0115] In this embodiment, the densities of the first pyramid structure and the second pyramid structure are different. That is, the number of first pyramid structures per unit area in the first textured region is a first quantity, and the number of second pyramid structures per unit area in the second textured region is a second quantity. The difference between the first quantity and the second quantity leads to a difference in the roughness of the first textured region 13 and the second textured region 14. This allows the first textured region 13 and the second textured region 14 to have different light-trapping effects, thereby balancing the light-trapping effect of the first surface of the substrate 11 and the quality of the functional film layer 12. For example, the first textured region 13 corresponds to the metallized region, and the second textured region 14 corresponds to the non-metallized region. In this case, the density of the first pyramid structure is greater than that of the second pyramid structure, and the roughness of the first textured region 13 is less than that of the second textured region 14. The first textured region 13 can provide a smoother substrate for the passivation layer (such as alumina or silicon nitride), ensuring its uniform and continuous coverage and obtaining excellent surface passivation effect. The second textured region 14 can extend the propagation path of light in the battery through stronger light scattering, increasing the probability of photogenerated carrier generation, thereby significantly improving the short-circuit current of the battery.

[0116] In some implementations, the boundary groove 15 extends discontinuously along its extension trajectory.

[0117] Specifically, such as Figure 11 As shown, the extension trajectory of the boundary groove 15 can coincide with the outer contour of the second texture area 14. (See also...) Figure 12 As shown, the boundary groove 15 may be discontinuous in at least some areas, and the extension trajectory of the boundary groove 15 is broken at the discontinuity. In the discontinuous areas of the boundary groove 15, there is no obvious boundary between the first texture area 13 and the second texture area 14. In this way, the manufacturing difficulty of the second texture area can be reduced.

[0118] In some implementations, such as Figure 12 As shown, the first textured area 13 has at least one first line groove 16.

[0119] In this embodiment, the light trapping effect of the first textured area 13 can be further enhanced by setting the first line groove.

[0120] In some implementations, such as Figure 12 As shown, the second textured area 14 has at least one first line groove 16.

[0121] In this embodiment, the light-trapping effect of the second textured area 14 can be further enhanced by the provision of the first line groove. For example, the first line groove 16 can extend in a meandering manner, and the extension contour of the first line groove 16 can be approximately straight.

[0122] In some embodiments, the extension direction of the first line groove 16 is not parallel to the extension direction of any boundary groove segment of the boundary groove 15.

[0123] Specifically, such as Figure 12 As shown, the first line groove 16 on the first textured area 13 is not parallel to the first boundary groove segment 15a, and the first line groove 16 on the second textured area 14 is not parallel to the first boundary groove segment 15a. Exemplarily, the extending directions of the different first line grooves 16 can be approximately the same, for example... Figure 12 In the first texture area 13, the extension directions of different first line grooves 16 can be roughly the same, and the extension directions of different first line grooves 16 in the second texture area 14 can be roughly the same. The extension directions of the first line grooves 16 in the first texture area 13 and the extension directions of the first line grooves 16 in the second texture area 14 can be roughly the same.

[0124] In some embodiments, the depth of the first line groove 16 is less than the depth of the junction groove 15. The top width of the first line groove 16 is less than the top width of the junction groove 15.

[0125] In this embodiment, the function of the first line groove 16 is to enhance the light trapping effect, and the first line groove 16 does not separate the first texture area 13 or the second texture area 14.

[0126] In some embodiments, the first surface 11a and the second surface 11b are the front surface and the rear surface, respectively.

[0127] Specifically, the first surface 11a is the front surface, an emitter is provided below the first textured region 13, and there is no emitter below the second textured region 14. The first textured region 13 and the second textured region 14 each have a certain light trapping effect. The emitter region below the first textured region 13 can form photogenerated carriers through the photoelectric effect.

[0128] In some implementations, the emitterless region below the second textured region 14 is a PN junctionless region.

[0129] In this embodiment, carrier recombination is minimized in the second textured region through the absence of a PN junction and effective surface passivation.

[0130] In some implementations, the emitterless region below the second textured region 14 has a residual PN junction.

[0131] In this embodiment, a residual PN junction may be present below the second textured area 14. This residual PN junction cannot generate a photoelectric effect, which can reduce the manufacturing difficulty of the second textured area 14.

[0132] In some implementations, the first texture area 13 is a metallized area and the second texture area 14 is a non-metallized area.

[0133] In this embodiment, the first textured region 13 is a metallized region and may be connected to an electrode. At the same time, the first textured region 13 has an emitter below it, and the generated photogenerated carriers can be directly transported to the collection region corresponding to the electrode position, which greatly reduces the lateral transmission distance and thus greatly reduces the recombination rate. The second textured region 14 is a non-metallized region and has no emitter below it or has very shallow doping, which reduces the recombination rate of the second textured region 14.

[0134] In some embodiments, the solar cell 100 may be a PERC cell (Passivated Emitter RearCell), an IBC cell (Interdigitated Back Contact), a TOPCon cell (Tunnel Oxide Passivated Contact), or a HIT / HJT cell (Heterojunction Technology).

[0135] For example, taking a TOPCon cell as an example, the structure of the solar cell 100 will be described in detail. Please refer to [link to relevant documentation]. Figure 13 As shown, the direction from the first surface 11a to the second surface 11b is defined as the third direction. The solar cell 100 includes a substrate 11, a first passivation layer 120 and a first antireflection layer 17 sequentially stacked on the first surface 11a along the direction away from the third direction, and a first electrode 181. The first electrode 181 is correspondingly disposed in the first texture region 13. The first electrode 181 sequentially passes through the first surface 11a, the first passivation layer 120 and the first antireflection layer 17 along the direction away from the third direction. The solar cell 100 also includes a tunneling oxide layer 191, a doped polycrystalline silicon layer 192, a back passivation layer 193 and a second antireflection layer 194 sequentially stacked on the second surface 11b along the third direction, and a second electrode 182. The second electrode 182 is disposed in the first texture region 13 along the third direction and sequentially passes through the doped polycrystalline silicon layer 192, the back passivation layer 193 and the second antireflection layer 194.

[0136] The first surface 11a of the substrate 11 is a positive surface. The first surface 11a of the substrate 11 includes a first textured area 13 and a second textured area 14. The emitter 131 is located below the first textured area 13, and there may be no emitter below the second textured area 14. A first passivation layer 120 covers the first textured area 13 and the second textured area 14. A first antireflection layer 17 covers the first passivation layer 120. A first electrode 181 is disposed in the area where the first textured area 13 is located. The first electrode 181 extends through the first antireflection layer 17 and the first passivation layer 120 in the thickness direction of the substrate 11 to the emitter 131 below the first textured area 13. The first electrode 181 is connected to the emitter 131.

[0137] The second surface 11b of the substrate 11 is the back surface. In the thickness direction of the substrate 11, along the direction from the first surface 11a to the second surface 11b, a tunneling oxide layer 191, a doped polysilicon layer 192, a back passivation layer 193 and a second antireflection layer 194 are sequentially deposited on the second surface 11b. The second electrode 182 is disposed in the region corresponding to the first texture region 13. In the thickness direction of the substrate 11, the second electrode 182 extends through the second antireflection layer 194 and the back passivation layer 193 to the doped polysilicon layer 192 along the direction from the second surface 11b to the first surface 11a. The second electrode 182 is connected to the doped polysilicon layer 192.

[0138] In some embodiments, the substrate 11 can be an N-type semiconductor substrate or a P-type semiconductor substrate. The N-type semiconductor substrate is doped with an N-type dopant element, which can be any one of group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type semiconductor substrate is doped with a P-type dopant element, which can be any one of group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0139] In some embodiments, the solar cell can be a single-sided cell, with the front surface (first surface 11a) serving as the light-receiving surface for receiving incident light and the back surface (second surface 11b) serving as the back-lighting surface.

[0140] In some embodiments, the solar cell can be a bifacial cell, meaning that both the first surface 11a and the second surface 11b of the substrate 11 can serve as light-receiving surfaces and can be used to receive incident light. The back surface (second surface 11b) can also receive incident light, but its efficiency in receiving incident light is somewhat lower than that of the light-receiving surface (first surface 11a).

[0141] In some embodiments, the emitter 131 may be formed by doping the original substrate 11. The emitter 131 and the substrate 11 are made of the same base material. Specifically, a portion of the original substrate corresponding to the first texture region 13 may be doped. The doped original substrate serves as the emitter 131, and the undoped original substrate serves as the substrate 11. Furthermore, the doping element type in the emitter 131 is different from the doping element type in the substrate 11. For example, if the substrate 11 is an N-type silicon substrate, the emitter 131 is formed by P-type doping of a portion of the N-type silicon substrate.

[0142] In some embodiments, the first passivation layer 120 can be a single-layer structure or a stacked structure, and the material used to prepare the first passivation layer 120 can be one or more of the following materials: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0143] In some embodiments, the material used to prepare the first antireflection layer 17 may be one or more of silicon nitride or silicon oxynitride.

[0144] In some embodiments, the tunneling oxide layer 191 may be a silicon dioxide layer.

[0145] In some embodiments, the doping type of the doped polysilicon layer 192 is the same as the doping type of the substrate 11. For example, if the substrate 11 is doped with an N-type dopant, then the doped polysilicon layer 192 is doped with an N-type dopant. The tunneling oxide layer 191 and the doped polysilicon layer 192 together form a passivation contact structure.

[0146] In some embodiments, the back passivation layer 193 can be a single-layer structure or a stacked structure, and the material used to prepare the back passivation layer 193 can be one or more of the following materials: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0147] In some embodiments, the material used to prepare the second antireflection layer 194 can be one or more of silicon nitride or silicon oxynitride.

[0148] In some embodiments, the first electrode 181 and the second electrode 182 have opposite polarities.

[0149] One embodiment of this application provides a stacked battery, which includes a top battery, an intermediate connecting layer and a bottom battery, wherein the intermediate connecting layer is connected between the top battery and the bottom battery.

[0150] 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 the aforementioned solar cell 100.

[0151] In some implementations, the interlayer can be a transparent material with a high refractive index. To reduce light reflection and absorption at the interlayer interface and achieve good conductivity to minimize the impact of series resistance on device performance, the interlayer typically needs to have high light transmittance. For example, the interlayer can be a transparent conductive metal oxide thin film (ITO).

[0152] One embodiment of this application provides a photovoltaic module 200. Please refer to [link / reference]. Figure 14 and Figure 15 As shown, it includes a battery string 201, an encapsulating film 202, and a cover plate 203. Please refer to [the provided text]. Figure 14 As shown, the battery string 201 is formed by connecting multiple solar cells 100 as described above, or the battery string 201 is formed by connecting multiple stacked cells as described above; the encapsulating film 202 is used to cover the surface of the battery string 201; the cover plate 203 is used to cover the surface of the encapsulating film 202 away from the surface of the battery string 201.

[0153] In some embodiments, multiple solar cells 100 can be electrically connected to each other by solder strips 20, which are connected to each pair of adjacent solar cells 100. The solder strips 20 are connected to the front surface of the first solar cell 100 and the back surface of the second solar cell 100, respectively.

[0154] In some embodiments, the solar cells 100 may be spaced apart, and during string bonding, the solder strip 20 extends from the front surface of the first solar cell 100 to the gap, passes through the gap, and extends to the back surface of the second solar cell 100.

[0155] In some embodiments, no gap is provided between the solar cells 100, that is, two adjacent solar cells 100 overlap each other.

[0156] In some embodiments, the encapsulating film 202 includes a first encapsulating film and a second encapsulating film. The first encapsulating film covers one of the front or back sides of the solar cell 100, and the second encapsulating film covers the other of the front or back sides of the solar cell 100. Specifically, at least one of the first or second encapsulating film can be an organic encapsulating film such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate copolymer (EVA) film, polyvinyl octene coelastomer (POE) film, or polyethylene terephthalate (PET) film.

[0157] Example 1 The structure of the solar cell in this embodiment 1 is as follows: Figure 11 and Figure 13As shown, the method for fabricating the solar cell in Example 1 includes the following steps: Step 1-1: Provide a texturized N-type silicon wafer. The front surface of the N-type silicon wafer has a first pyramid with an average size of 2μm to 5μm, an average height of 1.2μm to 2.8μm, and a density of 300,000 pyramids / mm². 2 Up to 500,000 pieces / mm 2 .

[0158] Steps 1-2 involve boron diffusion doping of the N-type silicon wafer to form an initial doped layer on the positive surface. The sheet resistance of the positive surface after boron diffusion doping is... .

[0159] Steps 1-3 involve using a laser to perform laser-induced film removal on the non-metallized region of the boron-diffused N-type silicon wafer's positive surface. This process removes at least a portion of the initial doped layer from the non-metallized region, yielding a first intermediate solar cell. The laser used is a picosecond ultraviolet laser (wavelength 266nm to 355nm, spot diameter 60μm to 500μm, frequency 600kHz, scanning speed 50m / s to 60m / s, single-pulse energy 1J / s). Up to 10J / ).

[0160] Steps 1-4 involve alkaline etching of the first solar cell intermediate with an alkaline etching solution to remove at least a portion of the initial doped layer thickness in the non-metallized regions, followed by secondary texturing of the non-laser-etched regions to form a second textured surface in the non-metallized regions, resulting in the second solar cell intermediate. The alkaline etching solution comprises an alkaline solution and an alkaline polishing additive; the alkaline solution is either NaOH or KOH solution. The second textured surface includes second pyramids with an average size of 2 μm to 5 μm, an average height of 1.2 μm to 2.8 μm, and a density of 300,000 pyramids / mm². 2 Up to 500,000 pieces / mm 2 .

[0161] Steps 1-5 involve oxidizing the second solar cell intermediate to oxidize the initial doped layer of at least a portion of the thickness of the metallized region on the front surface to form a first oxide layer and to form a second oxide layer of at least a portion of the thickness of the non-metallized region. The first oxide layer is borosilicate glass with a thickness of 60 nm to 150 nm, and the second oxide layer is also borosilicate glass with a thickness of 60 nm to 120 nm. Simultaneously, a third oxide layer is formed on the back surface, also made of borosilicate glass with a thickness of 60 nm to 150 nm. During the oxidation process of the second solar cell intermediate, the PN junction of the metallized region is advanced. After oxidation, the depth of the PN junction in the metallized region is 0.3 μm to 1.5 μm, and the surface concentration of boron in the metallized region is 4E17. Up to 9E18 .

[0162] Steps 1-6: Use hydrogen fluoride (HF) to remove the borosilicate glass from the back surface of the second cell intermediate. Then, polish the back surface of the second cell intermediate to expose a clean, flat, and parasitic-free N-type single-crystal silicon surface. The size of the tower base after back surface etching is 6μm to 18μm.

[0163] Steps 1-7: A tunneling oxide layer and a polycrystalline silicon layer are sequentially formed on the back surface of the second solar cell intermediate. The polycrystalline silicon layer is then phosphorus-doped to obtain a phosphorus-doped polycrystalline silicon layer (Poly). The thickness of the tunneling oxide layer is 1.2 nm to 2.2 nm, the thickness of the phosphorus-doped polycrystalline silicon layer (Poly) is 60 nm to 180 nm, and the phosphorus doping surface concentration is 1E20. up to 9E20 During this process, a portion of the phosphorus-doped polycrystalline silicon layer forms a fourth oxide layer, which is a phosphorus-silicon glass with a thickness ranging from 16 nm to 40 nm.

[0164] Steps 1-8: Use acid to remove the first and second oxide layers on the front surface, then use alkaline etching to remove the polycrystalline silicon layer plated around the front surface, and then use acid to remove the fourth oxide layer on the back surface and the remaining oxide layer on the front surface.

[0165] Steps 1-9 involve passivating the second battery cell intermediate to form passivation layers on the front and back surfaces, and then forming an anti-reflection layer covering the passivation layers to obtain the battery cell.

[0166] Steps 1-10: Print and sinter the first electrode on the front surface of the solar cell to form a first electrode, and print and sinter the second electrode on the back surface of the solar cell to form a second electrode, thus obtaining a solar cell.

[0167] The solar cell prepared in Example 1 has a textured area between the first textured region and the second textured region, as shown in the figure. Figures 2 to 4 The shown boundary trench has an area ratio of 0.8 between the first and second textured regions, and the boron doping concentration of the second textured region is 4E17. .

[0168] Example 2 The structure of the solar cell in Example 2 is basically the same as that in Example 1, except that the boron doping concentration in the second texture region of the solar cell in Example 2 is 2E17. .

[0169] Example 3 The structure of the solar cell in Example 3 is basically the same as that in Example 1, except that the boron doping concentration in the second texture region of the solar cell in Example 3 is 1E17. .

[0170] Example 4 The structure of the solar cell in Example 4 is basically the same as that in Example 1, except that the second textured region of the solar cell in Example 4 has no emitter, that is, the boron doping concentration in the second textured region is below the detection limit.

[0171] Accordingly, in steps 1-5 of Example 4, the second battery cell intermediate is oxidized to form a first oxide layer at least a portion of the thickness of the initial doped layer in the metallized region of the front surface, and a second oxide layer at least a portion of the thickness in the non-metallized region. The first oxide layer is borosilicate glass with a thickness of 60 nm to 150 nm, and the second oxide layer is a silicon oxide layer with a thickness of 60 nm to 120 nm. Simultaneously, a third oxide layer is formed on the back surface. The third oxide layer is borosilicate glass with a thickness of 60 nm to 150 nm. During the oxidation process of the second battery cell intermediate, the PN junction in the metallized region is advanced. After oxidation, the depth of the PN junction in the metallized region is 0.3 μm to 1.5 μm, and the surface concentration of boron in the metallized region is 4E17. Up to 9E18 .

[0172] Example 5 The structure of the solar cell in Example 5 is basically the same as that in Example 1, except that the area ratio of the first textured region to the second textured region in the solar cell of Example 5 is 0.2.

[0173] Example 6 The structure of the solar cell in Example 6 is basically the same as that in Example 1, except that the area ratio of the first textured region to the second textured region in the solar cell of Example 6 is 0.5.

[0174] Example 7 The structure of the solar cell in Example 7 is basically the same as that in Example 1, except that the area ratio of the first textured region to the second textured region in the solar cell of Example 7 is 1.

[0175] Example 8 The structure of the solar cell in Example 8 is basically the same as that in Example 1, except that the area ratio of the first textured region to the second textured region in the solar cell of Example 8 is 2.5.

[0176] Example 9 The structure of the solar cell in Example 9 is basically the same as that in Example 1, except that the area ratio of the first textured region to the second textured region in the solar cell of Example 9 is 5.

[0177] Comparative Example 1 The structure of the solar cell in Comparative Example 1 is basically the same as that in Example 1, except that the solar cell in Comparative Example 1 does not have a junction groove, and the first textured area and the second textured area in Comparative Example 1 do not have a clear boundary.

[0178] Comparative Example 2 The structure of the solar cell in Comparative Example 2 is basically the same as that in Example 1, except that the solar cell in Comparative Example 2 does not have a junction groove, and the first textured region and the second textured region of Comparative Example 2 have a junction groove. Figure 16 The diagram shows a sloping structure with a pyramid on it.

[0179] Performance testing The solar cells of Examples 1 to 9 and Comparative Examples 1 to 2 were subjected to performance comparison tests. The test conditions were as follows: using a pulsed solar simulator, under an ambient temperature of 25°C, AM1.5 atmospheric mass, and a solar irradiance of 1000 W / m², the electrical performance parameters of the cells, including photoelectric conversion efficiency (Eta), fill factor (FF), open-circuit voltage (Voc), and short-circuit current (Isc), were measured. The results are shown in Table 1. Table 1. Performance Test Comparison Table of Examples and Comparative Examples The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0180] The above embodiments merely illustrate preferred implementations of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the scope of protection of this patent application should be determined by the appended claims.

Claims

1. A solar cell, characterized in that, include: A substrate having a first surface and a second surface disposed opposite to each other along the thickness direction; the first surface and the second surface are a front surface and a rear surface, respectively. A functional film layer, including a passivation film layer and an antireflection film layer, wherein the functional film layer covers the first surface and the second surface of the substrate; The first surface includes at least one first texture area and at least one second texture area; the first texture area includes multiple first pyramid structures, and the second texture area includes multiple second pyramid structures; the average height of the upper surface of the first texture area is different from the average height of the upper surface of the second texture area, and there is a height difference ΔH between them; A boundary groove is provided between the first texture area and the second texture area; with the first surface of the substrate as the reference surface, the bottom depth of the boundary groove is d, and d≥ΔH is satisfied; Furthermore, the boundary groove is a continuous or discontinuous ring shape, and the boundary groove encloses and surrounds the second texture area.

2. The solar cell according to claim 1, characterized in that, The height difference ΔH between the average height of the upper surface of the first textured region and the average height of the upper surface of the second textured region is 0.1 nm to 10 μm.

3. The solar cell according to claim 1, characterized in that, The substrate has a first conductivity type doping, and the second conductivity type doping concentration of the second texture region is less than the second conductivity type doping concentration of the first texture region. The first conductivity type and the second conductivity type are opposite.

4. The solar cell according to claim 1, characterized in that, The substrate has a first conductivity type doping, and the second textured region does not have a second conductivity type doping, wherein the first conductivity type and the second conductivity type are opposite.

5. The solar cell according to claim 1, characterized in that, Several arrays of the second texture regions are distributed within the first texture region.

6. The solar cell according to claim 5, characterized in that, The ratio of the area of ​​the second texture region to the area of ​​the first texture region is 0.2 to 5.

7. The solar cell according to claim 1, characterized in that, The second texture area is polygonal in shape, and the boundary groove includes multiple boundary groove segments, which correspond to multiple edges of the second texture area respectively. The projection of the bottom of the boundary groove segment onto the first surface is a polygonal, curved, or sawtooth shape.

8. The solar cell according to claim 7, characterized in that, The second texture area is rectangular in shape.

9. The solar cell according to claim 1, characterized in that, The side of the first texture area facing the second texture area has a prismatic structure.

10. A stacked battery, characterized in that, include: Top cell, which can be a perovskite cell, cadmium telluride solar cell, copper indium gallium selenide solar cell, or gallium arsenide solar cell; Intermediate connection layer; and The base cell is the solar cell according to any one of claims 1 to 9; The top battery, the intermediate connecting layer, and the bottom battery are stacked and connected.

11. A photovoltaic module, characterized in that, Includes the solar cell according to any one of claims 1 to 9, or the tandem cell according to claim 10.

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