Photovoltaic cell, manufacturing method thereof and photovoltaic module

Abstract

The embodiment of the invention relates to the photovoltaic field, and provides a photovoltaic cell and a manufacturing method thereof, and a photovoltaic module, the photovoltaic cell comprises a substrate, the substrate is provided with a first surface and a second surface which are opposite, and the first surface is provided with first areas and second areas which are alternately arranged along a first direction; the substrate located in the second area comprises a bottom surface sunken towards the interior of the substrate, at least two inclined surfaces connected with the bottom surface and the first area and a step surface connected with the adjacent inclined surfaces, the bottom surface, the inclined surfaces and the step surface jointly define a groove, and the inclined surfaces incline towards the direction, close to the first area, of the second area; the bottom surface is a first suede comprising a plurality of first pyramids, the step surface is a second suede comprising a plurality of second pyramids, the tower footing size of the first pyramids is larger than that of the second pyramids, and the tower height of the first pyramids is larger than that of the second pyramids. According to the embodiment of the invention, the overall flatness of the second area is improved while the light trapping effect of the second area is improved at least.

Description

Technical Field

[0001] The present disclosure relates to the field of photovoltaics, and particularly to a photovoltaic cell, a manufacturing method thereof, and a photovoltaic module. Background Art

[0002] With the gradual depletion of fossil energy, photovoltaic cells, as a new energy alternative, are used more and more widely. A photovoltaic cell is a device that converts the light energy of the sun into electrical energy. The photovoltaic cell utilizes the photovoltaic effect to generate carriers, and then uses electrodes to lead out the carriers, so as to facilitate the effective utilization of electrical energy.

[0003] To improve the electrical performance of a photovoltaic cell, generally, a differential design is carried out on the area facing the electrode and the area not facing the electrode in the photovoltaic cell. For example, a stepped structure is formed on the surface of the substrate, and the electrode is located on the more convex part of the substrate.

[0004] However, due to the differences in the formation method of the stepped structure and the specific morphology of the stepped structure, it will affect the light absorption and utilization rate of the stepped structure, and the stepped structure will have an adverse effect on the uniformity of the film layer subsequently formed on the surface of the substrate, and ultimately will affect the photoelectric conversion efficiency of the photovoltaic cell. Therefore, it is necessary to further study how to design a stepped structure with a more suitable morphology. Summary of the Invention

[0005] Embodiments of the present disclosure provide a photovoltaic cell, a manufacturing method thereof, and a photovoltaic module, which are at least beneficial to improving the light trapping effect of the second region while improving the overall flatness of the second region.

[0006] According to some embodiments of the present disclosure, on the one hand, an embodiment of the present disclosure provides a photovoltaic cell, including: a substrate having opposite first and second surfaces, the first surface having a first region and a second region arranged alternately in a first direction; the substrate in the second region includes a bottom surface recessed into the substrate, at least two inclined surfaces connecting the bottom surface and the first region, and a stepped surface connecting adjacent inclined surfaces, the bottom surface, the inclined surfaces and the stepped surface jointly enclose a groove, and the inclined surfaces are inclined towards the first region; the bottom surface is a first velvet surface including a plurality of first pyramids, the stepped surface is a second velvet surface including a plurality of second pyramids, wherein the base size of the first pyramid is larger than the base size of the second pyramid, and the height of the first pyramid is larger than the height of the second pyramid.

[0007] In some embodiments, in the same groove, a plurality of the inclined surfaces and the stepped surface connecting adjacent inclined surfaces jointly form a slope, the orthographic projection area of the slope on the bottom surface is a first area, the area of the bottom surface is a second area, and the ratio of the first area to the second area is 0.005-0.02.

[0008] In some embodiments, the substrate located in the second region includes 2 of the inclined surfaces and 1 step surface connecting adjacent inclined surfaces. In the second direction, which is the thickness direction of the substrate, the distance between the step surface and the first region is a first distance, and the distance between the step surface and the bottom surface is a second distance. The ratio of the first distance to the second distance is 0.6 to 1.3.

[0009] In some embodiments, the inclined surfaces are inclined at an angle of 40° to 55° in the direction of the second region approaching the first region.

[0010] In some embodiments, the first region is a third textured surface including a plurality of third pyramids. The base size of the third pyramid is larger than the base size of the second pyramid and smaller than the base size of the first pyramid; and / or, the height of the third pyramid is greater than the height of the second pyramid and smaller than the height of the first pyramid; and / or, the reflectivity of the third textured surface is greater than the reflectivity of the second textured surface and smaller than the reflectivity of the first textured surface.

[0011] In some embodiments, the photovoltaic cell further includes: a first protective layer covering the bottom surface, the inclined surfaces, and the step surface.

[0012] In some embodiments, the material of the first protective layer includes a semiconductor material doped with a doping element, silicon oxide, phosphosilicate glass, or borosilicate glass.

[0013] According to some embodiments of the present disclosure, on the other hand, an embodiment of the present disclosure further provides a method for manufacturing a photovoltaic cell, including: providing an initial substrate, the initial substrate having an opposite initial first surface and an initial second surface, the initial first surface having an initial first region and an initial second region arranged alternately in a first direction; irradiating the initial second region with a laser spot having a gradually changing energy, so as to transform a part of the thickness of the initial substrate located in the initial second region into a damaged layer. Along the direction from the center to the edge of the laser spot, the energy change of the laser spot at least includes successively connected first, second, and third stages. The energy of the laser spot is at a first preset value in the first stage, the energy of the laser spot gradually increases from the first preset value to a second preset value in the second stage, and the energy of the laser spot gradually decreases from the second preset value to zero in the third stage; performing a first texturing treatment on the initial second region to at least remove the damaged layer and form grooves in the initial second region, and the remaining initial substrate is the substrate, the initial first region is transformed into the first region of the substrate, and the initial second region is transformed into the second region of the substrate. The substrate located in the second region includes a bottom surface recessed into the substrate, at least two inclined surfaces connecting the bottom surface and the first region, and a step surface connecting adjacent inclined surfaces. The bottom surface, the inclined surfaces, and the step surface together enclose the groove, and the inclined surfaces are inclined towards the first region; wherein, the bottom surface is a first textured surface including a plurality of first pyramids, the step surface is a second textured surface including a plurality of second pyramids, wherein the base size of the first pyramid is larger than the base size of the second pyramid, and the height of the first pyramid is greater than the height of the second pyramid.

[0014] In some embodiments, the energy of the laser spot is the irradiance of the laser spot. Along the direction from the center to the edge of the laser spot, the increase amount of the irradiance of the laser spot per 1 μm distance in the second stage is 0.008 J / mm 2 ~0.038 J / mm 2 ; the decrease amount of the irradiance of the laser spot per 1 μm distance in the third stage is 0.004 J / mm 2 ~0.02 J / mm 2 ; and / or, the first preset value is 0.01 J / mm 2 ~0.02 J / mm 2 ; the second preset value is 0.1 J / mm 2 ~0.2 J / mm 2 .

[0015] In some embodiments, the first etching solution used in the first texturing treatment includes potassium hydroxide and water, and the ratio of potassium hydroxide to water is 0.002 to 0.01:1; and / or, the treatment duration of the first texturing treatment is 200 s to 300 s; and / or, the process temperature of the first texturing treatment is 65°C to 75°C.

[0016] In some embodiments, the method for manufacturing the photovoltaic cell further includes: performing a high-temperature treatment or a high-temperature doping treatment on the groove to form a first protective layer covering the bottom surface, the inclined surface, and the stepped surface; forming a first doped semiconductor layer on the second surface, and the first doped semiconductor layer also being located on a partial area of the first surface; using the first protective layer as an etching barrier layer to perform an etching treatment on the first doped semiconductor layer located on the first surface.

[0017] In some embodiments, the process temperature of the high-temperature treatment or the high-temperature doping treatment is 900°C to 1050°C, and the treatment duration is 2000 s to 5000 s.

[0018] In some embodiments, after providing the initial substrate and before irradiating the initial second region with the laser spot having a gradually changing energy, the method for manufacturing the photovoltaic cell further includes: performing a second texturing treatment on the initial first surface to make the initial first surface include a plurality of third pyramids; performing a doping treatment on the initial first surface to transform a partial thickness of the initial substrate into a second doped semiconductor layer, and forming a second protective layer on a side of the second doped semiconductor layer away from the initial substrate; in the step of performing the first texturing treatment on the initial second region, using the second protective layer as an etching barrier layer to retain the second doped semiconductor layer located in the initial first region, and making the initial first region be a third textured surface including a plurality of the third pyramids, and the base size of the third pyramid being smaller than the base size of the second pyramid.

[0019] According to some embodiments of the present disclosure, on the other hand, the present disclosure embodiments further provide a photovoltaic module, including: a battery string formed by connecting a plurality of photovoltaic cells as described in any one of the above, or a photovoltaic cell formed by the manufacturing method of a plurality of photovoltaic cells as described in any one of the above; an encapsulation adhesive film for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulation adhesive film facing away from the battery string.

[0020] The technical solutions provided by the embodiments of the present disclosure have at least the following advantages:

[0021] The surface formed by multiple inclined surfaces and the stepped surfaces connecting adjacent inclined surfaces in the same groove is regarded as a slope. The groove with a slope can be regarded as a multi-layer stepped structure. On the one hand, it is beneficial to form a stepped light propagation path in the groove, enabling the light incident on the groove to experience multiple reflections between the inclined surfaces and the stepped surfaces, and ultimately being absorbed and utilized by the second region. On the other hand, the stepped light propagation path is conducive to extending the optical path to improve the absorption utilization rate of the slope for long-wavelength light, such as infrared light. Moreover, compared with the first pyramid included in the bottom surface, the base size and tower height of the second pyramid included in the stepped surface are both smaller. Firstly, it is beneficial to more evenly distribute the light incident on the slope with the smaller second pyramid, improving the overall light absorption utilization rate of the slope, reducing light escape, and further reducing the reflection loss of light on the slope. Secondly, it is beneficial to enhance the scattering of light on the slope to improve the absorption rate of the slope for short-wavelength light, such as blue light and ultraviolet light. Thus, through the comprehensive action of multiple aspects, it is possible to achieve a multi-level light trapping effect on the groove macroscopically and reduce the reflection loss of light on the groove microscopically, enabling the reception and utilization of more incident light at different angles from macro to micro, improving the light trapping effect of the second region, and thus enhancing the photoelectric conversion efficiency of the photovoltaic cell.

[0022] Moreover, as a transition region between the bottom surface and the first region, the slope is divided into at least two regions with height differences based on the design of the stepped surface. On the one hand, it is beneficial to improve the overall flatness of the second region, which is conducive to forming a film layer with uniform thickness on the first surface subsequently. And both the stepped surface and the multi-stage transition with smaller height differences can relieve the stress concentration during film deposition, reducing the risk of film cracking or peeling. On the other hand, it is beneficial to enable the photo-generated carriers in the second region to quickly migrate to the nearest first region, reducing the lateral transport distance of the photo-generated carriers to lower the recombination probability of the photo-generated carriers. Moreover, not only can the stepped surface avoid excessive or too low local light intensity in the slope, but the overall slope can also disperse the density of the photo-generated carriers to avoid excessive density of the photo-generated carriers near the electrode located on the first region, all of which are beneficial to reducing the risk of local hot spot effect in the photovoltaic cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] One or more embodiments are exemplarily illustrated by the pictures in the corresponding accompanying drawings. These exemplary illustrations do not constitute a limitation on the embodiments unless otherwise stated. The figures in the accompanying drawings do not constitute a scale limitation. To more clearly illustrate the technical solutions in the embodiments of the present disclosure or in the prior art, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the following-described accompanying drawings are only some embodiments of the present disclosure. For those of ordinary skill in the art, other accompanying drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 The first partial cross-sectional schematic diagram of a photovoltaic cell provided by an embodiment of the present disclosure;

[0025] Figure 2 is Figure 1 The first enlarged schematic diagram at the dashed box B in the shown structure;

[0026] Figure 3 is Figure 1 The second enlarged schematic diagram at the dashed box B in the shown structure;

[0027] Figure 4 A scanning electron microscope three-dimensional schematic of a substrate in a photovoltaic cell provided by an embodiment of the present disclosure;

[0028] Figure 5 The second partial cross-sectional schematic diagram of a photovoltaic cell provided by an embodiment of the present disclosure;

[0029] Figure 6 The third partial cross-sectional schematic diagram of a photovoltaic cell provided by an embodiment of the present disclosure;

[0030] Figure 7 A partial cross-sectional schematic diagram of an initial substrate provided in the manufacturing method of a photovoltaic cell according to another embodiment of the present disclosure;

[0031] Figure 8 A partial cross-sectional schematic diagram after forming a damaged layer in the manufacturing method of a photovoltaic cell according to another embodiment of the present disclosure;

[0032] Figure 9 A curve diagram corresponding to the energy gradient of a laser spot in the manufacturing method of a photovoltaic cell according to another embodiment of the present disclosure;

[0033] Figure 10 is at Figure 6 A partial cross-sectional schematic diagram after forming a first doped semiconductor layer on the basis of the shown structure;

[0034] Figure 11 is at Figure 10 A partial cross-sectional schematic diagram after etching treatment on the basis of the shown structure;

[0035] Figure 12 A partial cross-sectional schematic diagram after forming a second doped semiconductor layer and a second protective layer on an initial substrate in the manufacturing method of a photovoltaic cell according to another embodiment of the present disclosure;

[0036] Figure 13 A partial three-dimensional structure schematic diagram of a photovoltaic module provided by still another embodiment of the present disclosure;

[0037] Figure 14 is Figure 13Schematic cross-sectional structure view along section direction MM1. Detailed implementation manners

[0038] As can be seen from the background art, the photoelectric conversion efficiency of the photovoltaic cell needs to be improved.

[0039] The embodiments of the present disclosure provide a photovoltaic cell, a manufacturing method thereof, and a photovoltaic module. In the photovoltaic cell, the surface formed by multiple inclined planes in the same groove and the step surfaces connecting adjacent inclined planes is used as a slope. The groove with the slope can be regarded as a multi-step structure. On the one hand, it is beneficial to form a stepped light propagation path in the groove, so that the light incident on the groove can experience multiple reflections between the inclined planes and the step surfaces, and finally be absorbed and utilized by the second region. On the other hand, the stepped light propagation path is beneficial to extend the optical path to improve the absorption utilization rate of the slope for long-wavelength light, such as infrared light. On the other hand, compared with the first pyramid included in the bottom surface, the base size and tower height of the second pyramid included in the step surface are both smaller. First, it is beneficial to more evenly distribute the light incident on the slope with the smaller second pyramid, improve the overall light absorption utilization rate of the slope, reduce light escape, and further reduce the reflection loss of light on the slope. Second, it is beneficial to enhance the scattering of light on the slope to improve the absorption rate of the slope for short-wavelength light, such as blue light and ultraviolet light. Thus, with the comprehensive action of multiple aspects, it can not only achieve a multi-level light trapping effect on the groove macroscopically, but also reduce the reflection loss of light on the groove microscopically, realize receiving and utilizing more incident-angle light from macro to micro, improve the light trapping effect of the second region, and thus improve the photoelectric conversion efficiency of the photovoltaic cell. Moreover, as a transition region between the bottom surface and the first region, based on the design of the step surface, the transition region is divided into at least two height-difference regions. On the one hand, it is beneficial to improve the overall flatness of the second region, which is beneficial to forming a film layer with uniform thickness on the first surface subsequently, and both the step surface and the multi-stage small-height-difference transition can relieve the stress concentration degree during film layer deposition and reduce the risk of film layer cracking or peeling. On the other hand, it is beneficial to enable the photo-generated carriers in the second region to quickly migrate to the nearest first region, reduce the lateral transmission distance of the photo-generated carriers, and reduce the recombination probability of the photo-generated carriers. On the other hand, not only can the step surface avoid too high or too low local light intensity in the slope, but also the whole slope can disperse the density of the photo-generated carriers to avoid too large density of the photo-generated carriers near the electrode located on the first region, which are all beneficial to reducing the risk of local hot spot effect of the photovoltaic cell.

[0040] In the description of the embodiments of the present disclosure, technical terms such as "first" and "second" are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present disclosure, the meaning of "a plurality of" is more than two, unless otherwise specifically defined.

[0041] Reference to "an embodiment" herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present disclosure. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0042] In the description of the embodiments of the present disclosure, the term "and / or" is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: the existence of A, the simultaneous existence of A and B, and the existence of B. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0043] In the description of the embodiments of the present disclosure, the term "a plurality of" refers to more than two (including two). Similarly, "a plurality of groups" refers to more than two groups (including two groups), and "a plurality of pieces" refers to more than two pieces (including two pieces).

[0044] In the description of the embodiments of the present disclosure, technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. This is only for the convenience of describing the embodiments of the present disclosure and simplifying the description, and does not indicate or imply that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present disclosure.

[0045] In the description of the embodiments of the present disclosure, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to specific circumstances.

[0046] In the accompanying drawings corresponding to the embodiments of the present disclosure, for better understanding and description, the thickness and area of the layers are enlarged. When describing a component (such as a layer, film, region, or substrate) being on or on the surface of another component, the component can be "directly" on the surface of the other component, or there can be a third component between the two components. Conversely, when describing a component being on the surface of another component or when a surface of a component forms or is provided with another component, it means there is no third component between the two components. In addition, when describing a component being "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor on a partial edge of the entire surface.

[0047] In the description of the embodiments of the present disclosure, when a certain component "includes" another component, unless otherwise specified, other components are not excluded, and other components may further be included. In addition, when components such as layers, films, regions, or plates are referred to as being "on / located on" another component, it can be "directly on" the other component (i.e., on the surface of the other component with no other components therebetween), or there can be another component therebetween. In addition, when components such as layers, films, regions, plates, etc. are "directly located on" another component, or when components such as layers, films, regions, plates, etc. are located on the surface of another component, it means there are no other components located therebetween.

[0048] The terms used in the description of the various embodiments herein are only for describing specific embodiments and are not intended to be limiting. As used in the description of the various embodiments and the appended claims, "the component" is also intended to include the plural form, unless the context clearly indicates otherwise. Among them, the component includes components such as layers, films, regions, or plates.

[0049] The following will elaborate on the embodiments of the present disclosure in conjunction with the accompanying drawings. However, those of ordinary skill in the art can understand that in the embodiments of the present disclosure, many technical details are provided for readers to better understand the embodiments of the present disclosure. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions required to be protected by the embodiments of the present disclosure can still be achieved.

[0050] An embodiment of the present disclosure provides a solar cell. The following will detail the solar cell provided by an embodiment of the present disclosure in conjunction with the accompanying drawings.

[0051] Reference Figures 1 to 4, the photovoltaic cell includes: a substrate 100 having opposite first and second surfaces 101 and 102, the first surface 101 having first regions 111 and second regions 121 arranged alternately in a first direction X; the substrate 100 in the second region 121 includes a bottom surface 131 recessed into the substrate 100, at least two inclined surfaces 161 connecting the bottom surface 131 and the first regions 111, and a stepped surface 171 connecting adjacent inclined surfaces 161, the bottom surface 131, the inclined surfaces 161 and the stepped surface 171 together enclose a groove 151, and the inclined surfaces 161 are inclined towards the first regions 111; the bottom surface 131 is a first matte surface including a plurality of first pyramids 131a, and the stepped surface 171 is a second matte surface including a plurality of second pyramids 171a, wherein the base size of the first pyramids 131a is larger than the base size of the second pyramids 171a, and the height of the first pyramids 131a is greater than the height of the second pyramids 171a.

[0052] Wherein, Figure 1 is the first partial cross-sectional schematic diagram of the photovoltaic cell provided by an embodiment of the present disclosure; Figure 2 is Figure 1 the first enlarged schematic diagram at the dashed box B in the shown structure; Figure 3 is Figure 1 the second enlarged schematic diagram at the dashed box B in the shown structure; Figure 4 is a three-dimensional scanning electron microscope schematic diagram of the substrate in the photovoltaic cell provided by an embodiment of the present disclosure.

[0053] It should be noted that since the single groove 151 has at least two inclined surfaces 161 and at least one stepped surface 171, the groove 151 can be regarded as a multi-layer stepped structure. The surface formed by the multiple inclined surfaces 161 in the same groove 151 and the stepped surfaces 171 connecting adjacent inclined surfaces 161 is taken as the slope 141. On the one hand, it is beneficial to form a stepped light propagation path in the groove 151 by means of the slope 141, so that the light incident on the groove 151 can experience multiple reflections between the inclined surfaces 161 and the stepped surfaces 171 and is finally absorbed and utilized by the second region 121. On the other hand, the stepped light propagation path is beneficial to extending the optical path to improve the absorption utilization rate of the slope 141 for long-wavelength light, such as infrared light. On the other hand, the stepped surface 171 is designed as a second suede surface including multiple second pyramids 171a. Compared with the first pyramids 131a included in the bottom surface 131, the base size and height of the second pyramids 171a are both smaller. First, it is beneficial to more evenly distribute the light incident on the slope 141 by means of the smaller second pyramids 171a, avoid excessive or too low local light intensity in the slope 141, improve the overall light absorption utilization rate of the slope 141, reduce light escape, further reduce the reflection loss of light on the slope 141, and improve the photoelectric conversion efficiency of the photovoltaic cell under low-light conditions or oblique light conditions. Second, it is beneficial to enhance the scattering of light on the slope 141 to improve the absorption rate of the slope 141 for short-wavelength light, such as blue light and ultraviolet light. In this way, through the combined action of multiple aspects, the multi-layer stepped structure formed by the inclined surfaces 161 and the stepped surfaces 171 achieves a multi-level light trapping effect macroscopically, and the stepped surface 171, which is a second suede surface including multiple second pyramids 171a, can microscopically reduce the reflection loss of light on the groove 151, realizing that more incident angles of light can be received and utilized from macro to micro, so as to improve the light trapping effect of the second region 121, thereby increasing the short-circuit current of the photovoltaic cell and improving the photoelectric conversion efficiency of the photovoltaic cell.

[0054] Moreover, as a transition region between the bottom surface 131 and the first region 111, the slope 141 is divided into at least two height-difference regions based on the design of the step surface 171. On the one hand, it is beneficial to reduce the steepness of the slope 141. In other words, it improves the overall flatness of the second region 121, which is conducive to forming a film layer with uniform thickness on the first surface 101 subsequently. Moreover, the step surface 171 and the multi-stage transitions with smaller height differences can relieve the stress concentration during film deposition, reducing the risk of film cracking or peeling. On the other hand, it is beneficial for the photo-generated carriers in the second region 121 to migrate quickly to the nearest first region 111, reducing the lateral transport distance of the photo-generated carriers to lower the recombination probability of the photo-generated carriers, which is conducive to improving the photoelectric conversion efficiency of the photovoltaic cell. On the other hand, not only can the step surface 171 avoid too high or too low local light intensity in the slope 141, but the slope 141 as a whole can disperse the density of the photo-generated carriers to avoid too high density of photo-generated carriers near the electrode located on the first region 111, both of which are beneficial to reducing the risk of local hot spot effect in the photovoltaic cell.

[0055] It should be emphasized that in some cases, the pyramid does not exist uniformly in the inclined surface 161, and only the step surface 171 includes a plurality of second pyramids 171a. The inclined surface 161 is a smooth surface to further improve the overall flatness of the second region 121 and enhance the thickness uniformity of the film layer formed on the second region 121 subsequently. It should be noted that the inclined surface 161 being a smooth surface is in comparison with the step surface 171 including the second pyramids 171a. Due to the influence of the forming process, the surface of the inclined surface 161 is not necessarily as smooth as a polished surface. It may also have minute protrusions or depressions, but it does not have a typical pyramid structure, and its overall flatness is much higher than that of the step surface 171.

[0056] It should be emphasized that the photovoltaic cell may further include an electrode disposed at least on the first surface 101 for extracting the photo-generated carriers generated in the substrate 100. Based on this, for the convenience of describing the specific orientation of the first pyramid 131a and the second pyramid 171a on the first surface 101, for those skilled in the art, the first surface 101 may be divided into a first region 111 and a second region 121. The first region 111 at least includes the region where the positive projection of the electrode on the substrate 100 is located, and the region on the first surface 101 other than the first region 111 is the second region 121. Among them, in order to ensure that the film layer contacted by the electrode has a relatively high doping concentration or the regions contacted by the electrode are all high-concentration regions, thereby reducing the contact resistance, generally, the positive projection area of the first region 111 is greater than or equal to the positive projection area of the electrode. In other words, the positive projection area of the electrode on the substrate 100 is smaller than the area of the first region 111 and the positive projection position must be within the first region 111. It should be noted that the number of the first regions 111 and the number of the second regions 121 may both be multiple, and the first regions 111 and the second regions 121 are alternately arranged along the first direction X. In other words, the first region 111 may be located in the interval between adjacent second regions 121, and the second region 121 may also be located in the interval between adjacent first regions 111.

[0057] Furthermore, to further illustrate the difference between the first pyramid 131a and the second pyramid 171a, for those skilled in the art, the second region 121 may be divided into one transition region 122, one second sub-region 123, and another transition region 122 arranged in sequence along the first direction X. Among them, one transition region 122 is used to refer to the region occupied by one slope 141 on the second region 121, and one second sub-region 123 is used to refer to the region occupied by one bottom surface 131 on the second region 121. In other words, the first pyramid 131a is located in the second sub-region 123, and the second pyramid 171a is located in the transition region 122. In addition, the two first regions 111 located on the opposite sides of the same second region 121 along the first direction X are respectively connected to one transition region 122.

[0058] A more detailed description of an embodiment of the present disclosure will be given below with reference to the accompanying drawings.

[0059] Refer to Figure 2 or Figure 3, if the base size of the first pyramid 131a is designed to be larger than that of the second pyramid 171a, then within the same arrangement area, the arrangement quantity of the first pyramid 131a is lower than that of the second pyramid 171a. In other words, compared with the arrangement density of the first pyramid 131a on the bottom surface 131, the arrangement density of the second pyramid 171a on the stepped surface 171 is greater. On the one hand, it is beneficial to increase the surface area and specific surface area of the stepped surface 171, so that the stepped surface 171 has more surfaces for receiving incident light, which is conducive to enabling more light to be reflected, refracted or absorbed and utilized by the stepped surface 171; on the other hand, it is beneficial to reduce the gap between adjacent second pyramids 171a, so that the stepped surface 171 can capture incident light more effectively, reduce the probability of light escaping from between adjacent second pyramids 171a, and the more numerous second pyramids 171a can disperse incident light more evenly, making it easier for the incident light to enter the substrate 100 and then be absorbed and utilized; on the other hand, it is beneficial to reduce the sensitivity of the stepped surface 171 to the incident angle of the incident light, so that the stepped surface 171 can maintain a high light absorption rate at different illumination angles.

[0060] It should be noted that the base size of the pyramid structure includes any one of the length, width or diagonal length of the orthographic projection pattern of the bottom of the pyramid structure on the second surface 102. For example, taking the orthographic projection pattern of the bottom of the pyramid structure on the second surface 102 as a regular quadrilateral, the base size of the pyramid structure is any one of the length, width or diagonal length of the regular quadrilateral. In addition, the pyramid structures mentioned in this article include the first pyramid 131a, the second pyramid 171a and the third pyramid mentioned later.

[0061] In practical applications, the orthographic projection pattern of the bottom of the pyramid structure on the second surface can also be an irregular polygon. In this case, the length, width, or diagonal length of the orthographic projection pattern of the bottom of the pyramid structure on the second surface is not absolute, but is artificially defined to represent the base size of the pyramid structure. For example, when the orthographic projection pattern of the bottom of the pyramid structure on the second surface is an irregular quadrilateral, the length of the base of the pyramid structure can be defined as the length of the longest side of the irregular quadrilateral, the width of the base of the pyramid structure can be defined as the length of the shortest side of the irregular quadrilateral, and the diagonal length of the base of the pyramid structure can be defined as the length of the longest diagonal of the irregular quadrilateral. It can be understood that the above is only an exemplary description, and in practice, it can be flexibly defined according to actual needs. In addition, the orthographic projection pattern of the bottom of the pyramid structure on the second surface can be other irregular polygons, circles, or irregular shapes similar to circles. In this case, the base size of the pyramid structure is to select multiple regions with different specific areas in the bottom of the pyramid structure. The specific area of the region can be flexibly defined according to actual needs, and then the average value of the length, width, diagonal, or diameter of multiple regions with different specific areas is obtained.

[0062] In some examples, the base size of the second pyramid 171a can be 0.5 μm to 1.5 μm. For example, it can be 0.6 μm, 0.7 μm, 0.8 μm, or 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, or 1.4 μm, etc.; the base size of the first pyramid 131a can be 2 μm to 3 μm. For example, it can be 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, or 2.9 μm, etc.

[0063] In one example, the base of the second pyramid 171a can be a quadrilateral of 1 μm * 1 μm, and the base of the first pyramid 131a can be a quadrilateral of 2.5 μm * 2.5 μm.

[0064] Reference Figure 2 or Figure 3 , it is designed that the tower height of the first pyramid 131a is greater than the tower height of the second pyramid 171a. In this way, compared with the first pyramid 131a, the second pyramid 171a with a lower tower height is also beneficial to reducing the transmission distance of photo-generated carriers at the step surface 171, thereby being beneficial to reducing the recombination probability of carriers and improving the photoelectric conversion efficiency of the photovoltaic cell.

[0065] It should be noted that the tower height of the pyramid refers to the distance between the tower tip of the pyramid and the base in the second direction Y. The second direction Y is the direction from the second surface 102 to the first surface 101. In other words, the second direction Y is the thickness direction of the base 100.

[0066] In some examples, the tower height of the second pyramid 171a can be 0.5 μm to 1.5 μm. For example, it can be 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, or 1.4 μm, etc.; the tower height of the first pyramid 131a can be 2 μm to 3 μm. For example, it can be 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, or 2.9 μm, etc.

[0067] In some embodiments, referring to Figures 1 to 3 , the reflectivity of the stepped surface 171 of the second matte surface is less than the reflectivity of the bottom surface 131 of the first matte surface.

[0068] In some examples, the reflectivity of the stepped surface 171 can be 10 to 11. For example, it can be 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, or 10.9, etc.; the reflectivity of the bottom surface 131 can be 12 to 13. For example, it can be 12.1, 12.2, 12.3, 12.4, 12.5, 12.6, 12.7, 12.8, or 12.9, etc.

[0069] In some embodiments, referring to Figures 1 to 3 , in the same groove 151, a plurality of inclined surfaces 161 and the stepped surface 171 connecting adjacent inclined surfaces 161 together form a slope 141. The orthographic projection area of the slope 141 on the bottom surface 131 is the first area, and the area of the bottom surface 131 is the second area. The ratio of the first area to the second area can be 0.005 to 0.02. For example, it can be 0.006, 0.007, 0.008, 0.009, 0.01, 0.011, 0.012, 0.013, 0.014, 0.015, 0.016, 0.017, 0.018, or 0.019, etc.

[0070] It should be noted that since both the first region 111 and the second region 121 extend along the third direction, the groove 151 can be regarded as a long groove extending along the third direction, and the extension dimensions of the bottom surface 131, the inclined surface 161, and the stepped surface 171 in the third direction are the same. The area sizes of the orthographic projections of the bottom surface 131 and the slope 141 on the bottom surface 131 mainly depend on the lengths of the orthographic projections of the bottom surface 131 and the slope 141 on the bottom surface 131 in the first direction X. Based on this, the length of the bottom surface 131 in the first direction X is taken as the first length L1, and the length of the orthographic projection of the slope 141 on the bottom surface 131 in the first direction X is taken as the second length L2. The ratio of the first area to the second area is designed to be 0.005 to 0.02, that is, the ratio of the second length L2 to the first length L1 is designed to be 0.005 to 0.02. Then, the surface area of the groove 151 is mainly determined by the area of the bottom surface 131. It is designed that the tower height of the first pyramid 131a included in the bottom surface 131 is higher, which is beneficial to providing a larger surface area and more attachment points, enabling the film layer deposited on the surface of the groove 151 subsequently to adhere better. That is, it is beneficial to make the deposited film layer, such as a passivation layer, an antireflection layer, or a transparent conductive layer, cover the surface of the groove 151 more uniformly, thereby helping to reduce defects and pores in the film layer and improving the quality and performance of the film layer.

[0071] In some cases, referring to Figure 2 or Figure 3 , in the first direction X, the first length L1 of the bottom surface 131 can be 200 μm to 800 μm. For example, the first length L1 can be 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, 600 μm, 650 μm, 700 μm, or 750 μm, etc.

[0072] In some embodiments, referring to Figure 2 or Figure 3 , the substrate 100 located in the second region 121 can include 2 inclined surfaces 161 and 1 stepped surface 171 connecting adjacent inclined surfaces 161. In the second direction Y, the distance between the stepped surface 171 and the first region 111 is the first distance H5, and the distance between the stepped surface 171 and the bottom surface 131 is the second distance H6. The ratio of the first distance H5 to the second distance H6 can be 0.6 to 1.3. The second direction Y is the thickness direction of the substrate 100. In addition, the depth of the groove 151 can be the sum of the first distance H5 and the second distance H6.

[0073] It should be noted that the plane where the bottom surfaces of most of the second pyramids 171a included in the stepped surface 171 are located is used as the reference plane of the stepped surface 171, and the reference plane of the stepped surface 171 is used as the first reference plane; the plane where the bottom surfaces of most of the first pyramids 131a included in the bottom surface 131 are located is used as the reference plane of the bottom surface 131, and the reference plane of the bottom surface 131 is the second reference plane. Along the second direction Y, the first distance H5 between the stepped surface 171 and the first region 111 refers to the distance between the first reference plane and the reference plane where the first region 111 is located; the second distance H6 between the stepped surface 171 and the bottom surface 131 refers to the distance between the first reference plane and the second reference plane.

[0074] In addition, the bottom surface of the second pyramid 171a is the plane where the base of the second pyramid 171a is located, and the orthographic projection pattern of the base of the second pyramid 171a on the base 100 can be a regular quadrilateral or an irregular polygon. It should be noted that the bottom surfaces of all the second pyramids 171a included in the stepped surface 171 may be in different planes, but the bottom surfaces of more than half of the second pyramids 171a are almost in the same plane, and this plane can be used as the reference plane of the stepped surface 171. The bottom surface of the first pyramid 131a is the plane where the base of the first pyramid 131a is located, and the orthographic projection pattern of the base of the first pyramid 131a on the base 100 can be a regular quadrilateral or an irregular polygon. It should be noted that the bottom surfaces of all the first pyramids 131a included in the bottom surface 131 may be in different planes, but the bottom surfaces of more than half of the first pyramids 131a are almost in the same plane, and this plane can be used as the reference plane of the bottom surface 131.

[0075] Moreover, in practical applications, it can be designed that the base in the second region includes (N + 1) inclined surfaces and N stepped surfaces connecting adjacent inclined surfaces. N can be other positive integers in addition to 1. For example, N can be 2, 3, or 4, etc.

[0076] In some cases, referring to Figure 3 , the first region 111 is a third velvet surface including a plurality of third pyramids 111a. The bottom surfaces of all the third pyramids 111a included in the first region 111 may be in different planes, but the bottom surfaces of more than half of the third pyramids 111a are almost in the same plane, and this plane can be used as the third reference plane. Based on this, the first distance H5 is the distance between the first reference plane where the stepped surface 171 is located and the third reference plane where the first region 111 is located.

[0077] It should be noted that Figure 2 or Figure 3 both schematically show the first reference plane of the stepped surface 171 and the second reference plane of the bottom surface 131 with dotted lines of higher density; Figure 3The third reference plane of the first region 111 is schematically shown by a dashed line with a relatively high density in the middle.

[0078] In some examples, referring to Figure 2 or Figure 3 , along the second direction Y, the ratio of the first distance H5 to the second distance H6 can be 0.7, 0.8, 0.9, 1, 1.1, 1.2, etc.

[0079] In some examples, along the second direction Y, the first distance H5 between the stepped surface 171 and the first region 111 can be 5 μm to 7 μm. For example, it can be 5.1 μm, 5.2 μm, 5.3 μm, 5.4 μm, 5.5 μm, 5.6 μm, 5.7 μm, 5.8 μm, 5.9 μm, 6 μm, 6.1 μm, 6.2 μm, 6.3 μm, 6.4 μm, 6.5 μm, 6.6 μm, 6.7 μm, 6.8 μm, or 6.9 μm, etc.

[0080] In some examples, along the second direction Y, the second distance H6 between the stepped surface 171 and the bottom surface 131 can be 5.5 μm to 7.5 μm. For example, it can be 5.6 μm, 5.7 μm, 5.8 μm, 5.9 μm, 6 μm, 6.1 μm, 6.2 μm, 6.3 μm, 6.4 μm, 6.5 μm, 6.6 μm, 6.7 μm, 6.8 μm, 6.9 μm, 7 μm, 7.1 μm, 7.2 μm, 7.3 μm, or 7.4 μm, etc.

[0081] In some embodiments, referring to Figure 2 or Figure 3 , the inclination angle β of the inclined surface 161 inclined towards the direction where the second region 121 approaches the first region 111 can be 40° to 55°. For example, the inclination angle β can be 40.5°, 41°, 41.5°, 42°, 42.5°, 43°, 43.5°, 44°, 44.5°, 45°, 45.5°, 46°, 46.5°, 47°, 47.5°, 48°, 48.5°, 49°, 49.5°, 50°, 50.5°, 51°, 51.5°, 52°, 52.5°, 53°, 53.5°, 54°, or 54.5°, etc. It should be noted that the inclination angles β of different inclined surfaces 161 inclined towards the first region 111 can be the same or have slight differences, but the numerical range of the inclination angle β of any inclined surface 161 inclined towards the first region 111 can be 40° to 55°.

[0082] It should be noted that the inclination angle β of the designed inclined surface 161 inclined towards the first region 111 is 40° to 55°, which can prevent the inclined surface 161 from being too steep. As the transition part between the bottom surface 131 and the first region 111, the inclined surface 161 is beneficial to reducing the height difference between different regions on the inclined surface 161. In other words, taking the second surface 102 as the reference surface, it is beneficial to reduce the height difference between adjacent different regions on the inclined surface 161 along the first direction X, so that the topography of the first surface 101 gradually transitions from the relatively high first region 111 to the relatively low bottom surface 131, which is conducive to forming a film layer with a uniform thickness, such as a passivation film layer, on the first surface 101 subsequently, thereby improving the passivation effect of the passivation film layer.

[0083] In addition, if the inclination angle β of the designed inclined surface 161 inclined towards the first region 111 is less than 40°, compared with the inclination angle β being greater than or equal to 40° and less than 40°, when the surface area of the inclined surface 161 remains unchanged, the size of the transition region 122 in the first direction X will increase, thereby reducing the number of first regions 111 that can be arranged on the entire first surface 101. Therefore, designing the inclination angle β of the inclined surface 161 inclined towards the first region 111 to be greater than or equal to 40° is beneficial to reducing the overall size of the inclined surface 161 in the first direction X while ensuring that the inclined surface 161 has a certain surface area, that is, reducing the proportion of the transition region 122 in the entire first surface 101.

[0084] It should be noted that with reference to Figure 2 or Figure 3 , the plane where the bottom surfaces of most of the first pyramids 131a included in the bottom surface 131 are located is used as the reference surface of the bottom surface 131. Based on this, the inclination angle β of the inclined surface 161 inclined towards the first region 111 refers to the acute angle formed by the inclined surface 161 and the reference surface of the bottom surface 131.

[0085] In some embodiments, with reference to Figure 3 , the first region 111 is a third suede surface including a plurality of third pyramids 111a. The size relationships among the first pyramid 131a, the second pyramid 171a, and the third pyramid 111a will be described in detail below.

[0086] In some cases, with reference to Figure 3 , the base size of the third pyramid 111a is larger than the base size of the second pyramid 171a and smaller than the base size of the first pyramid 131a. In other words, the base size of the second pyramid 171a is the smallest, and the base size of the first pyramid 131a is the largest.

[0087] In some examples, the base size of the third pyramid 111a can be from 1 μm to 2 μm. For example, it can be 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, or 1.9 μm, etc.; the base size of the second pyramid 171a can be from 0.5 μm to 1.5 μm; the base size of the first pyramid 131a can be from 2 μm to 3 μm.

[0088] In some cases, referring to Figure 3 , the height of the third pyramid 111a is greater than the height of the second pyramid 171a and less than the height of the first pyramid 131a. In other words, the height of the second pyramid 171a is the smallest, and the height of the first pyramid 131a is the largest.

[0089] In some examples, the height of the third pyramid 111a can be from 1.5 μm to 2.5 μm. For example, it can be 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2 μm, 2.1 μm, 2.2 μm, 2.3 μm, or 2.4 μm, etc.; the height of the second pyramid 171a can be from 0.5 μm to 1.5 μm; the height of the first pyramid 131a can be from 2 μm to 3 μm.

[0090] In some cases, referring to Figure 3 , the reflectivity of the third matte surface is greater than the reflectivity of the second matte surface and less than the reflectivity of the first matte surface. In other words, the reflectivity of the stepped surface 171 is the smallest, and the reflectivity of the bottom surface 131 is the largest.

[0091] In some examples, the reflectivity of the first region 111 of the third matte surface can be from 10.5 to 11.5. For example, it can be 10.6, 10.7, 10.8, 10.9, 11, 11.1, 11.2, 11.3, or 11.4, etc.; the reflectivity of the stepped surface 171 can be from 10 to 11; the reflectivity of the bottom surface 131 can be from 12 to 13.

[0092] It should be noted that for the first surface 101, the above three cases can exist simultaneously, or one can be selected, or two can be selected.

[0093] In some embodiments, referring to Figure 3 , the apex angles of the first pyramid 131a, the second pyramid 171a, and the third pyramid 111a can all be from 65° to 80°. For example, it can be 66°, 67°, 68°, 69°, 70°, 71°, 72°, 73°, 74°, 75°, 76°, 77°, 78°, or 79°, etc. In this way, it is beneficial to more effectively capture the incident light with the pyramid having a smaller apex angle. For example, light at more incident angles can be reflected into the first surface 101, so as to increase the total amount of light entering the first surface 101.

[0094] It should be noted that the included angle between two relatively arranged side edges in the pyramid can be regarded as the apex angle of the pyramid.

[0095] In some embodiments, referring to Figure 5 , Figure 5 , which is a second partial cross-sectional schematic diagram of a photovoltaic cell provided by an embodiment of the present disclosure. The photovoltaic cell may further include: a first protective layer 103, covering the bottom surface 131, the inclined surface 161, and the stepped surface 171.

[0096] In some cases, the first protective layer 103 can conformally cover the bottom surface 131, the inclined surface 161, and the stepped surface 171. Then, the surface topography of the part of the first protective layer 103 facing the bottom surface 131 also presents a matte surface topography similar to that of the bottom surface 131, and the surface topography of the part of the first protective layer 103 facing the stepped surface 171 also presents a matte surface topography similar to that of the stepped surface 171. It should be noted that in combination with reference to Figures 2 to 5 , on the one hand, the first protective layer 103 is beneficial to protecting the topography of the first pyramid 131a and the second pyramid 171a. For example, when other film layers are formed on the second region 121 and patterned subsequently, the first protective layer 103 can serve as an etching barrier layer to avoid damage to the first pyramid 131a and the second pyramid 171a by the patterning process, thereby being beneficial to ensuring that the second region 121 has a low reflectivity.

[0097] On the other hand, the first protective layer 103 is beneficial to improving the optical performance of the second region 121 to further reduce the reflection loss of the second region 121. For example, reducing the reflectivity of the overall surface of the photovoltaic cell located in the second region 121 to ultimately improve the light absorption and utilization rate of the second region 121, thereby improving the photoelectric conversion efficiency of the photovoltaic cell.

[0098] In some cases, after forming the first protective layer 103 through an oxygen-free high-temperature process, the reflectivity of the overall surface of the photovoltaic cell located in the second region 121 can be reduced by about 0.1 - 0.3 on the original basis; in other cases, after forming the first protective layer 103 through an oxygen-containing high-temperature process, the reflectivity of the overall surface of the photovoltaic cell located in the second region 121 can be reduced by about 0.5 - 1 on the original basis; in still other cases, after forming the first protective layer 103 through a source-passing high-temperature process, the reflectivity of the overall surface of the photovoltaic cell located in the second region 121 can be reduced by about 0.5 - 1 on the original basis. The oxygen-free high-temperature process, the oxygen-containing high-temperature process, and the source-passing high-temperature process will be described in detail later.

[0099] In some embodiments, referring to Figure 5, the material of the first protective layer 103 may include a semiconductor material doped with a doping element, silicon oxide, phosphosilicate glass, or borosilicate glass.

[0100] In some cases, the semiconductor material included in the first protective layer 103 may be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon or germanium. Among them, the elemental semiconductor material may be in single crystal state, polycrystalline state, amorphous state, or microcrystalline state (a state with both single crystal state and amorphous state is called microcrystalline state). For example, silicon may be at least one of single crystal silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. In other cases, the semiconductor material included in the first protective layer 103 may also be a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, silicon germanide, silicon carbide, gallium arsenide, indium gallium, perovskite, cadmium telluride, or copper indium selenide and other materials.

[0101] In some cases, the doping element included in the first protective layer 103 may be an N-type doping element or a P-type doping element. Among them, the N-type doping element may be at least one of group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As); the P-type doping element may be at least one of group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0102] In some embodiments, the material of the substrate 100 may be an elemental semiconductor material or a compound semiconductor material.

[0103] In some cases, the substrate 100 may be an N-type semiconductor substrate doped with an N-type doping element; in other cases, the substrate 100 may be a P-type semiconductor substrate doped with a P-type doping element.

[0104] In some embodiments, refer to Figure 6 , Figure 6 , which is a third partial cross-sectional schematic diagram of a photovoltaic cell provided by an embodiment of the present disclosure. The photovoltaic cell may further include: a tunneling layer 108 located on the second surface 102; a first doped semiconductor layer 105 doped with a first doping element, located on the side of the tunneling layer 108 away from the second surface 102; a second doped semiconductor layer 106 doped with a second doping element, located on the first region 111, the conduction types of the first doping element and the second doping element; a first passivation layer 118 located on the side of the first doped semiconductor layer 105 away from the tunneling layer 108; a second passivation layer 128 located on the side of the second doped semiconductor layer 106 away from the substrate 100 and located on the second region 121; a first electrode 109 embedded in the first passivation layer 118 and in ohmic contact with the first doped semiconductor layer 105; a second electrode 119 embedded in the second passivation layer 128 and in ohmic contact with the second doped semiconductor layer 106.

[0105] It should be noted that, as a selective emitter structure on the first surface 101, the second doped semiconductor layer 106 is conducive to ensuring that the second electrode 119 has good current collection efficiency based on the second doped semiconductor layer 106, while avoiding the second region 121 being covered by the second doped semiconductor layer 106, thereby avoiding the parasitic absorption of light incident on the second region 121 by the second doped semiconductor layer 106, improving the utilization rate of incident light on the first surface 101, and improving the photoelectric conversion efficiency of the photovoltaic cell.

[0106] In addition, the tunneling layer 108 and the first doped semiconductor layer 105 together form a passivated contact structure. The tunneling layer 108 chemically passivates the second surface 102, saturates the dangling bonds on the second surface 102, reduces the density of defect states on the second surface 102, and reduces the probability of carrier recombination on the second surface 102. The first doped semiconductor layer 105 field-passivates the second surface 102, reduces the concentration of minority carriers to reduce the probability of carrier recombination on the second surface 102, thereby improving the photoelectric conversion efficiency of the photovoltaic cell. In addition, the first passivation layer 118 can further passivate the second surface 102 and act as an optical optimization layer for the second surface 102 to improve the absorption and utilization rate of light by the second surface 102; the second passivation layer 128 can passivate the first surface 101 to reduce the density of defect states on the first surface 101 and act as an optical optimization layer for the first surface 101 to improve the absorption and utilization rate of light by the first surface 101.

[0107] In some cases, the second doped semiconductor layer 106 doped with the second doping element is formed in the initial state of the substrate 100. In other words, there is no obvious boundary between the second doped semiconductor layer 106 and the substrate 100 located in the first region 111. Figure 6 For the convenience of illustration, the substrate 100 and the second doped semiconductor layer 106 are drawn with different filling methods. On this basis, the slope 141 of the groove 151 formed by the depression of the substrate 100 located in the second region 121 towards the second surface 102 can be regarded as being jointly formed by the second doped semiconductor layer 106 and the substrate 100 located in the first region 111.

[0108] In some cases, the material of the tunneling layer 108 may include at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or magnesium fluoride; the material of the first doped semiconductor layer 105 may include at least one of amorphous silicon, polycrystalline silicon, or silicon carbide. The first doped semiconductor layer 105 and the substrate 100 may both be doped with the first doping element.

[0109] In some cases, both the second passivation layer 128 and the first passivation layer 118 can be a single-layer structure or a stacked structure. In addition, the materials of the second passivation layer 128 and the first passivation layer 118 can both include at least one of aluminum oxide, silicon oxide, silicon nitride, or silicon oxynitride.

[0110] In some cases, the substrate 100 can be an N-type semiconductor substrate doped with an N-type doping element, the first doping element doped in the first doped semiconductor layer 105 is an N-type doping element, and the second doping element doped in the second doped semiconductor layer 106 is a P-type doping element; in other cases, the substrate 100 can be a P-type semiconductor substrate doped with a P-type doping element, the first doping element doped in the first doped semiconductor layer 105 is a P-type doping element, and the second doping element doped in the second doped semiconductor layer 106 is an N-type doping element.

[0111] In summary, taking the surface composed of multiple inclined surfaces 161 in the same groove 151 and the step surfaces 171 connecting adjacent inclined surfaces 161 together as the slope 141, the groove 151 with the slope 141 can be regarded as a multi-layer step structure. On the one hand, it is beneficial to form a stepped light propagation path in the groove 151, so that the light incident on the groove 151 can experience multiple reflections between the inclined surfaces 161 and the step surfaces 171, and finally be absorbed and utilized by the second region 121; on the other hand, the stepped light propagation path is beneficial to extend the optical path to improve the absorption utilization rate of the slope 141 for long-wavelength light, such as infrared light; on the other hand, compared with the first pyramid 131a included in the bottom surface 131, the base size and tower height of the second pyramid 171a included in the step surface 171 are both smaller. First, it is beneficial to more evenly distribute the light incident on the slope 141 with the smaller second pyramid 171a, improve the overall light absorption utilization rate of the slope 141, reduce light escape, and further reduce the reflection loss of light on the slope 141. Second, it is beneficial to enhance the scattering of light on the slope 141 to improve the absorption rate of the slope 141 for short-wavelength light, such as blue light and ultraviolet light. In this way, through the comprehensive action of multiple aspects, it can not only achieve a multi-level light trapping effect on the groove 151 macroscopically, but also reduce the reflection loss of light on the groove 151 microscopically, realizing that more incident angles of light can be received and utilized from macro to micro, so as to improve the light trapping effect of the second region 121, and thus improve the photoelectric conversion efficiency of the photovoltaic cell.

[0112] Moreover, as a transition region between the bottom surface 131 and the first region 111, the slope 141 is divided into at least two regions with height differences based on the design of the step surface 171. On the one hand, it is beneficial to improve the overall flatness of the second region 121, which is conducive to forming a film layer with uniform thickness on the first surface 101 subsequently. Moreover, the step surface 171 and the transitions with multiple smaller height differences can alleviate the stress concentration during film deposition, reducing the risk of film cracking or peeling. On the other hand, it is beneficial to enable the photo-generated carriers in the second region 121 to migrate quickly to the nearest first region 111, reducing the lateral transport distance of the photo-generated carriers to lower the recombination probability of the photo-generated carriers. On the other hand, not only can the step surface 171 avoid excessive or insufficient local light intensity in the slope 141, but the overall slope 141 can also disperse the density of the photo-generated carriers to avoid excessive density of the photo-generated carriers near the electrode located on the first region 111, both of which are beneficial to reducing the risk of local hot spot effect in the photovoltaic cell.

[0113] Another embodiment of the present disclosure further provides a manufacturing method of a photovoltaic cell for forming the photovoltaic cell provided in the foregoing embodiment. The manufacturing method of the photovoltaic cell provided in another embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings. Figures 7 to 12 FIG. is a partial cross-sectional structural schematic diagram corresponding to each step in the manufacturing method of the photovoltaic cell provided in another embodiment of the present disclosure. It should be noted that the same or corresponding parts as those in the foregoing embodiment will not be described in detail here.

[0114] With reference to Figures 7 to 12 and Figures 1 to 4 the manufacturing method of the photovoltaic cell may at least include the following steps:

[0115] S1: With reference to Figure 7 and Figure 7 FIG. is a partial cross-sectional schematic diagram of an initial substrate provided in the manufacturing method of the photovoltaic cell provided in another embodiment of the present disclosure. An initial substrate 110 is provided. The initial substrate 110 has opposite initial first surface 120 and initial second surface 130. The initial first surface 120 has initial first regions 140 and initial second regions 150 arranged alternately in the first direction X.

[0116] It should be noted that the initial first surface 120 corresponds to the first surface formed subsequently, the initial first region 140 corresponds to the first region of the first surface formed subsequently, the initial second region 150 corresponds to the second region of the first surface formed subsequently, and the initial second surface 130 corresponds to the second surface formed subsequently.

[0117] S2: With reference to Figures 7 to 9, the initial second region 150 is irradiated with a laser spot having a gradually changing energy to convert a partial thickness of the initial substrate 110 located in the initial second region 150 into a damaged layer 104. Along the direction from the center to the edge of the laser spot, the energy change of the laser spot at least includes successively connected first stage I, second stage II, and third stage III. The energy of the laser spot is at a first preset value in the first stage I, the energy of the laser spot gradually increases from the first preset value to a second preset value in the second stage II, and the energy of the laser spot gradually decreases from the second preset value to zero in the third stage III. In other words, along the direction from the center to the edge of the laser spot, the energy of the laser spot first remains unchanged, then gradually increases, and finally gradually decreases to zero.

[0118] It should be noted that Figure 8 is a partial cross-sectional view after forming a damaged layer in the manufacturing method of a photovoltaic cell provided in another embodiment of the present disclosure; Figure 9 is a curve graph corresponding to the energy gradient of the laser spot in the manufacturing method of a photovoltaic cell provided in another embodiment of the present disclosure. In addition, Figure 9 uses the center of the laser spot as the 0 point.

[0119] S3: With reference to Figure 8 and Figures 1 to 4 , the initial second region 150 is subjected to a first texturing treatment to at least remove the damaged layer 104 and form a groove 151 in the initial second region 150. The remaining initial substrate 110 is the substrate 100, the initial first region 140 is transformed into the first region 111 of the substrate 100, and the initial second region 150 is transformed into the second region 121 of the substrate 100. The substrate 100 located in the second region 121 includes a bottom surface 131 recessed into the substrate 100, at least two inclined surfaces 161 connecting the bottom surface 131 and the first region 111, and a step surface 171 connecting adjacent inclined surfaces 161. The bottom surface 131, the inclined surfaces 161, and the step surface 171 together enclose the groove 151, and the inclined surfaces 161 are inclined towards the first region 111.

[0120] Among them, the bottom surface 131 is a first textured surface including a plurality of first pyramids 131a, and the step surface 171 is a second textured surface including a plurality of second pyramids 171a. Among them, the base size of the first pyramid 131a is larger than the base size of the second pyramid 171a, and the height of the first pyramid 131a is greater than the height of the second pyramid 171a.

[0121] It should be emphasized that during the process of irradiating the initial second region 150 with a laser spot having a gradually changing energy in step S2, only the damaged layer 104 will be formed in the initial second region 150, and no stepped structure with a height difference will be formed between the initial first region 140 and the initial second region 150. On this basis, in step S3, by virtue of the difference in the etching rates of the damaged layer 104 in the initial second region 150 and the initial first region 140 during the first texturing process, the initial second region 150 is transformed into the second region 121 having the grooves 151.

[0122] Furthermore, based on the design in step S2 that along the direction from the center to the edge of the laser spot, the energy of the laser spot first remains unchanged, then gradually increases, and finally gradually decreases to zero, it is beneficial to make the thickness of the damaged layer 104 vary in some different regions. Generally speaking, in the initial substrate 110 irradiated by the part with greater energy in the laser spot, the damage caused by the laser is greater, and the thickness of the formed damaged layer 104 is greater or the interior is more thoroughly damaged. For example, along the direction from the center of the initial second region 150 to the initial first region 140, the thickness of the damaged layer 104 first remains unchanged, then gradually increases, then maintains an average value again, then gradually increases again, and finally gradually decreases to zero. On this basis, in step S3, there will be a difference in the etching rates of different regions of the damaged layer 104 during the first texturing process, and there will also be a difference in the time consumed by the first texturing process to remove the damaged layer 104 with different thicknesses. Then, the first texturing process will expose the initial substrate 110 covered by some different regions in the damaged layer 104 at different times, so as to texture some regions of the remaining initial substrate 110 at different times. Therefore, it is beneficial to form the groove 151 jointly surrounded by the bottom surface 131, the inclined surface 161, and the stepped surface 171, and different texture structures are formed only on the bottom surface 131 and the stepped surface 171. Specifically, the bottom surface 131 forms the first texture surface including a plurality of first pyramids 131a, and the stepped surface 171 forms the second texture surface including a plurality of second pyramids 171a.

[0123] In other words, under the combined action of irradiating the initial second region 150 with a laser spot having a gradually changing energy in step S2 and the first texturing process in step S3, the turning points of the etching rates of some different regions of the film layer jointly composed of the damaged layer 104 and the remaining initial substrate 110 during the first texturing process are different along the direction from the center of the initial second region 150 to the initial first region 140. Further, the average etching rates of some different regions of the film layer jointly composed of the damaged layer 104 and the remaining initial substrate 110 during the first texturing process gradually change, for example, first remain unchanged, then gradually decrease, then remain unchanged again, and finally gradually decrease to zero, thus being beneficial to finally forming the groove 151 with a multi-step structure.

[0124] In some embodiments, with reference to Figure 9 and Figure 2 or Figure 3 , the position with the maximum energy of the laser spot, i.e., the second preset value, irradiates on the bottom surface 131 of the groove 151 and irradiates on the area of the bottom surface 131 close to the inclined surface 161. It should be noted that the energy of a single laser spot reaches the second preset value in two different regions, and the two second preset values irradiate on the regions of the bottom surface 131 close to two different inclined surfaces 161 respectively.

[0125] In some cases, along the first direction X, the distance between the irradiation position of the bottom surface 131 corresponding to the second preset value and the junction of the inclined surface 161 and the bottom surface 131 is a preset distance D. The ratio of the preset distance D to the first length L1 of the bottom surface 131 can be 0.0025 - 0.05. For example, it can be 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04 or 0.045, etc.

[0126] It should be noted that the first length L1 of the bottom surface 131 is formed by multiple lasers opening the film in parallel. The surface area of the groove 151 is mainly determined by the first length L1 of the bottom surface 131, and the value range of the first length L1 is relatively large. Based on this, the value range of the ratio of the preset distance D to the first length L1 of the bottom surface 131 is also relatively large. However, compared with the first length L1 of the bottom surface 131, the preset distance D between the irradiation position of the bottom surface 131 corresponding to the second preset value and the junction of the inclined surface 161 and the bottom surface 131 is relatively small. In other words, the position irradiated by the turning point of the laser spot energy reduction is very close to the finally required inclined surface 161.

[0127] In some examples, the preset distance D between the irradiation position of the bottom surface 131 corresponding to the second preset value and the junction of the inclined surface 161 and the bottom surface 131 can be 5μm - 10μm. For example, the preset distance D can be 5.2μm, 5.5μm, 5.8μm, 6μm, 6.3μm, 6.5μm, 6.6μm, 6.8μm, 7μm, 7.3μm, 7.5μm, 7.7μm, 8μm, 8.2μm, 8.5μm, 8.8μm, 9μm, 9.3μm or 9.5μm, etc.

[0128] In some examples, the overall size of the laser spot can be 50 μm to 200 μm. In other words, the diameter of the laser spot can be 50 μm to 200 μm. For example, it can be 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, or 190 μm, etc.

[0129] In some examples, with reference to Figure 8 and Figure 9 , when a single laser spot is divided symmetrically into two parts along the center, in the first direction X, the width of the irradiation area of the laser spot corresponding to the first stage I in any one of the two parts on the initial second region 150 can be 20 μm to 50 μm. For example, it can be 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm, 36 μm, 37 μm, 38 μm, 39 μm, 40 μm, 41 μm, 42 μm, 43 μm, 44 μm, 45 μm, 46 μm, 47 μm, 48 μm, or 49 μm, etc.; the width of the irradiation area of the laser spot corresponding to the second stage II in any one of the two parts on the initial second region 150 can be 5 μm to 10 μm. For example, it can be 5.2 μm, 5.5 μm, 5.6 μm, 5.8 μm, 6 μm, 6.2 μm, 6.5 μm, 6.6 μm, 7 μm, 7.2 μm, 7.5 μm, 7.8 μm, 8 μm, 8.2 μm, 8.5 μm, 8.8 μm, 9.2 μm, 9.2 μm, 9.5 μm, or 9.8 μm, etc.; the width of the irradiation area of the laser spot corresponding to the third stage III in any one of the two parts on the initial second region 150 can be 10 μm to 25 μm. For example, it can be 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, or 24 μm, etc.

[0130] It should be noted that designing the width of the irradiation area of the laser spot corresponding to the second stage II on the initial second region 150 to be 5 μm to 10 μm, and designing the width of the irradiation area of the laser spot corresponding to the third stage III on the initial second region 150 to be 10 μm to 25 μm is beneficial to increasing the overall length of the transition region 122 in the first direction X, facilitating the formation of the stepped surface 171 on the transition region 122, and ensuring that the stepped surface 171 has a sufficient surface area to layout the second pyramid 171a.

[0131] In some embodiments, with reference to Figure 9, the energy of the laser spot is the irradiance of the laser spot. Along the direction from the center of the laser spot to the edge, the increase in the irradiance of the laser spot per 1 μm distance in the second stage II can be 0.008 J / mm 2 ~0.038 J / mm 2 , the decrease in the irradiance of the laser spot per 1 μm distance in the third stage III can be 0.004 J / mm 2 ~0.02 J / mm 2 .

[0132] It should be noted that the growth rate of the irradiance of the laser spot in the second stage II can be greater than the decrease rate of the irradiance of the laser spot in the third stage III, which is beneficial to finally forming a bottom surface 131 with a longer length in the first direction X and forming a slope 141 with a lower steepness; further, designing that both the growth rate of the irradiance of the laser spot in the second stage II and the decrease rate of the irradiance of the laser spot in the third stage III are smaller is beneficial to finally forming a stepped surface 171 between adjacent inclined surfaces 161 while forming the inclined surface 161, and facilitating the first texturing treatment to form a textured surface only on the bottom surface 131 and the stepped surface 171.

[0133] In some examples, along the direction from the center of the laser spot to the edge, the increase in the irradiance of the laser spot per 1 μm distance in the second stage II can be 0.009 J / mm 2 、0.01 J / mm 2 、0.011 J / mm 2 、0.012 J / mm 2 、0.013 J / mm 2 、0.014 J / mm 2 、0.015 J / mm 2 、0.016 J / mm 2 、0.017 J / mm 2 、0.018 J / mm 2 、0.019 J / mm 2 、0.02 J / mm 2 、0.021 J / mm 2 、0.022 J / mm 2 、0.023 J / mm 2 、0.024 J / mm 2 、0.025 J / mm 2 、0.026 J / mm 2 、0.027 J / mm 2 、0.028 J / mm 2 、0.029 J / mm 2 、0.03 J / mm2 、0.031 J / mm 2 、0.032 J / mm 2 、0.033 J / mm 2 、0.034 J / mm 2 、0.035 J / mm 2 、0.036 J / mm 2 or 0.037 J / mm 2 etc.

[0134] In some examples, in the direction from the center to the edge of the laser spot, the reduction amount of the irradiance of the laser spot per 1 μm distance in the third stage III can be 0.005 J / mm 2 、0.006 J / mm 2 、0.007 J / mm 2 、0.008 J / mm 2 、0.009 J / mm 2 、0.01 J / mm 2 、0.011 J / mm 2 、0.012 J / mm 2 、0.013 J / mm 2 、0.014 J / mm 2 、0.015 J / mm 2 、0.016 J / mm 2 、0.017 J / mm 2 、0.018 J / mm 2 or 0.019 J / mm 2 etc.

[0135] It should be noted that irradiance characterizes the amount of radiant energy received per unit area per unit time on the surface irradiated by the radiant energy, that is, the radiant flux density on the irradiated surface.

[0136] In some embodiments, referring to Figure 9 ,the first preset value can be 0.01 J / mm 2 ~0.02 J / mm 2 ,for example, it can be 0.011 J / mm 2 、0.012 J / mm 2 、0.013 J / mm 2 、0.014 J / mm 2 、0.015 J / mm 2 、0.016 J / mm 2 、0.017 J / mm 2 、0.018 J / mm 2 or 0.019 J / mm 2etc.; the second preset value is 0.1 J / mm 2 ~0.2 J / mm 2 , for example, it can be 0.11 J / mm 2 、0.12 J / mm 2 、0.13 J / mm 2 、0.14 J / mm 2 、0.15 J / mm 2 、0.16 J / mm 2 、0.17 J / mm 2 、0.18 J / mm 2 or 0.19 J / mm 2 etc.

[0137] In some embodiments, with reference to Figure 8 and Figures 1 to 4 , the first etching solution used in the first texturing treatment may include potassium hydroxide and water, and the ratio of potassium hydroxide to water may be 0.002~0.01:1. For example, it can be 0.003, 0.004, 0.005, 0.006, 0.007, 0.008 or 0.009, etc.

[0138] In some embodiments, the treatment duration of the first texturing treatment may be 200 s~300 s. For example, it can be 205 s, 210 s, 215 s, 220 s, 225 s, 230 s, 235 s, 240 s, 245 s, 250 s, 255 s, 260 s, 265 s, 270 s, 275 s, 280 s, 285 s, 290 s or 295 s, etc.

[0139] In some embodiments, the process temperature of the first texturing treatment may be 65 °C~75 °C. For example, it can be 66 °C, 67 °C, 68 °C, 69 °C, 70 °C, 71 °C, 72 °C, 73 °C or 74 °C, etc.

[0140] In some embodiments, with reference to Figure 1 and Figure 5 、 Figure 10 and Figure 11 , the manufacturing method of the photovoltaic cell may further include: with reference to Figure 1 and Figure 5 , performing a high-temperature treatment or a high-temperature doping treatment on the groove 151 to form a first protective layer 103 covering the bottom surface 131, the inclined surface 161 and the stepped surface 171; with reference to Figure 5 and Figure 10 , forming a first doped semiconductor layer 105 on the second surface 102, and the first doped semiconductor layer 105 is also located on a partial area of the first surface 101; with reference to Figure 10 and Figure 11, using the first protective layer 103 as an etching barrier layer, the first doped semiconductor layer 105 located on the first surface 101 is etched.

[0141] Among them, Figure 10 is a partial cross-sectional schematic diagram after forming the first doped semiconductor layer on the basis of the structure shown in Figure 6 ; Figure 11 is a partial cross-sectional schematic diagram after etching on the basis of the structure shown in Figure 10 .

[0142] It should be noted that during the process of forming the first doped semiconductor layer 105 on the second surface 102, there will be a phenomenon of overplating, so the first doped semiconductor layer 105 will also be formed on some regions located on the first surface 101. Subsequently, the first doped semiconductor layer 105 located on the first surface 101 needs to be etched. During the etching process, the first protective layer 103 can be used as an etching barrier layer to avoid damaging the first pyramid 131a and the second pyramid 171a, which is beneficial to ensuring that the second region 121 has a low reflectivity. In addition, the first protective layer 103 is beneficial to improving the optical performance of the second region 121 to further reduce the reflection loss of the second region 121. For example, reducing the reflectivity of the overall surface of the photovoltaic cell located in the second region 121 to improve the absorption and utilization rate of light by the second region 121 on the final first surface 101, thereby improving the photoelectric conversion efficiency of the photovoltaic cell.

[0143] In some cases, the process temperature of the high-temperature treatment or high-temperature doping treatment can be 900°C to 1050°C, and the treatment duration can be 2000s to 5000s.

[0144] In some examples, the process temperature of the high-temperature treatment or high-temperature doping treatment can be 910°C, 920°C, 930°C, 940°C, 950°C, 960°C, 970°C, 980°C, 990°C, 1000°C, 1010°C, 1020°C, 1030°C or 1040°C, etc.

[0145] In some examples, the treatment duration of the high-temperature treatment or high-temperature doping treatment can be 2100s, 2200s, 2300s, 2400s, 2500s, 2600s, 2700s, 2800s, 2900s, 3000s, 3100s, 3200s, 3300s, 3400s, 3500s, 3600s, 3700s, 3800s, 3900s, 4000s, 4100s, 4200s, 4300s, 4400s, 4500s, 4600s, 4700s, 4800s or 4900s, etc.

[0146] In some cases, the high-temperature treatment can be an oxygen-free high-temperature process. By directly performing a high-temperature treatment on the groove 151, the part of the substrate 100 with a thickness corresponding to the groove 151 can be transformed into the first protective layer 103. In some examples, the substrate 100 is a semiconductor material doped with a doping element. Based on the oxygen-free high-temperature process, it is beneficial to increase the concentration of the doping element in the part of the substrate 100 near the groove 151, so as to form the first protective layer 103 with a different doping element concentration from that in the remaining substrate 100. Then, the material of the first protective layer 103 is also a semiconductor material including a doped doping element. It should be noted that after forming the first protective layer 103 through the oxygen-free high-temperature process, the reflectivity of the overall photovoltaic cell on the surface of the second region 121 can be reduced by about 0.1 to 0.3 on the original basis.

[0147] In other cases, the high-temperature treatment can be an oxygen-containing high-temperature process. While performing a high-temperature treatment on the groove 151, an oxidation treatment is also performed on the groove 151, which can oxidize the part of the substrate 100 with a thickness corresponding to the groove 151 to form the first protective layer 103. In some examples, the substrate 100 can include a silicon material. Based on the oxygen-containing high-temperature process, the first protective layer 103 including silicon oxide can be formed. It should be noted that after forming the first protective layer 103 through the oxygen-containing high-temperature process, the reflectivity of the overall photovoltaic cell on the surface of the second region 121 can be reduced by about 0.5 to 1 on the original basis.

[0148] In still other cases, the high-temperature doping treatment can be a source-passing high-temperature process. While performing a high-temperature treatment on the groove 151, a doping treatment and an oxidation treatment are also performed on the groove 151, so that the part of the substrate 100 with a thickness corresponding to the groove 151 is transformed into the first protective layer 103, and the first protective layer 103 is an oxidized material doped with a doping element. In some examples, the substrate 100 can include a silicon material. Based on the source-passing high-temperature process, the first protective layer 103 including phosphosilicate glass or borosilicate glass can be formed.

[0149] It should be noted that after forming the first protective layer 103 through the source-passing high-temperature process, the reflectivity of the overall photovoltaic cell on the surface of the second region 121 can be reduced by about 0.5 to 1 on the original basis. In addition, phosphosilicate glass or borosilicate glass are only two examples of the first protective layer 103 formed based on the source-passing high-temperature process. In practical applications, the doping sources provided in the source-passing high-temperature process can include other group V elements or other group III elements.

[0150] In other embodiments, in the step of performing high-temperature treatment on the groove 151, an additional film layer may not be formed. The high temperature provided by the high-temperature treatment only repairs the laser damage to reduce the density of defect states on the surface of the groove 151, thereby reducing the recombination centers of carriers at the groove 151, and thus improving the photoelectric conversion efficiency of the photovoltaic cell.

[0151] In some cases, during the formation of the first doped semiconductor layer 105, a first dielectric layer (not shown in the figure) is further formed on the side of the first doped semiconductor layer 105 away from the second surface 102. In one example, the substrate 100 is an N-type semiconductor substrate, the first doped semiconductor layer 105 is polysilicon doped with an N-type doping element, and the material of the first dielectric layer may be phosphosilicate glass.

[0152] Based on this, the step of etching the first doped semiconductor layer 105 located on the first surface 101 may include: removing the first dielectric layer located on the first surface 101 by using a chain hydrofluoric acid process; removing the first doped semiconductor layer 105 not covered by the first dielectric layer by using an alkali polishing process, so that the first doped semiconductor layer 105 located on the second surface 102 is retained.

[0153] In some cases, referring to Figure 6 , before forming the first doped semiconductor layer 105, the manufacturing method may further include: forming a tunneling layer 108 on the second surface 102. Subsequently, the first doped semiconductor layer 105 is formed on the side of the tunneling layer 108 away from the substrate 100. It should be noted that the formation process of the tunneling layer 108 in the manufacturing method provided by another embodiment of the present disclosure is not limited.

[0154] In some embodiments, with reference to Figure 7 and Figure 12 , after providing the initial substrate 110 and before irradiating the initial second region 150 with a laser spot having a gradually changing energy, the manufacturing method of the photovoltaic cell may further include: with reference to Figure 7 and Figure 12 , performing a second texturing treatment on the initial first surface 120 so that the initial first surface 120 includes a plurality of third pyramids 111a; continuing to refer to Figure 12 , performing a doping treatment on the initial first surface 120 so that a partial thickness of the initial substrate 110 is transformed into a second doped semiconductor layer 106, and forming a second protective layer 107 on the side of the second doped semiconductor layer 106 away from the initial substrate 110; with reference to Figure 12 and Figure 3, in the step of performing the first texturing process on the initial second region 150, with the second protective layer 107 as the etching barrier layer, the second doped semiconductor layer 106 located in the initial first region 140 is retained, and the initial first region 140 is made into a third textured surface including a plurality of third pyramids 111a, and the base size of the third pyramid 111a is smaller than the base size of the second pyramid 171a.

[0155] Wherein, Figure 12 is a partial cross-sectional schematic diagram after forming a second doped semiconductor layer and a second protective layer on an initial substrate in the manufacturing method of a photovoltaic cell provided by another embodiment of the present disclosure.

[0156] It should be noted that the initial first surface 120 includes a plurality of third pyramids 111a, which is convenient for subsequently forming the first region 111 into a third textured surface including a plurality of third pyramids 111a. In addition, different texturing processes are respectively used to form the initial first surface 120 including a plurality of third pyramids 111a and to form the groove 151.

[0157] Moreover, with reference to Figure 12 and Figure 8 , during the process of irradiating the initial second region 150 with a laser spot having a gradually changing energy in step S2, both the second protective layer 107 and the second doped semiconductor layer 106 located on the initial second region 150 will be transformed into a damaged layer 104; with reference to Figure 12 and Figure 3 , the second protective layer 107 located on the initial first region 140 that is not irradiated by the laser spot serves as an etching barrier layer in step S3, so as to achieve retaining only the first region 111 as a third textured surface including a plurality of third pyramids 111a. In addition, referring to Figure 6 , the remaining second doped semiconductor layer 106 is only located on the first region 111 to serve as a selective emitter structure located on the first surface 101, which is beneficial to reducing the contact resistance between the subsequently formed second electrode and the second doped semiconductor layer 106 while reducing the probability of carrier recombination in other regions of the first surface 101, so as to improve the photoelectric conversion efficiency of the finally formed photovoltaic cell.

[0158] In one example, the substrate 100 is an N-type semiconductor substrate, the second doped semiconductor layer 106 is a semiconductor material doped with a P-type doping element, such as a boron diffusion layer; the material of the second protective layer 107 can be borosilicate glass.

[0159] It should be noted that the size relationship among the first pyramid 131a, the second pyramid 171a, and the third pyramid 111a is the same as that in the foregoing embodiment, and will not be elaborated here.

[0160] In some cases, with reference to Figure 10 and Figure 11, after adopting an alkaline polishing process to remove the first doped semiconductor layer 105 not covered by the first dielectric layer, such that the first doped semiconductor layer 105 located on the second surface 102 is retained, the manufacturing method may further include: with reference to Figure 12 and Figure 3 , adopting an acid pickling process to remove the remaining second protective layer 107 located on the initial first region 140. It should be noted that by controlling the process parameters of the acid pickling process, such as the process duration, it is possible to remove only the second protective layer 107 by means of the acid pickling process and retain the first protective layer 103, or it is also possible to remove both the second protective layer 107 and the first protective layer 103 by means of the acid pickling process.

[0161] In some cases, with reference to Figure 6 , after forming the first doped semiconductor layer 105 and the second doped semiconductor layer 106, the manufacturing method may further include: forming a first passivation layer 118, the first passivation layer 118 being located on the side of the first doped semiconductor layer 105 away from the tunneling layer 108; forming a second passivation layer 128, the second passivation layer 128 being located on the side of the second doped semiconductor layer 106 away from the substrate 100 and on the second region 121; forming a first electrode 109, the first electrode 109 being embedded in the first passivation layer 118 and making an ohmic contact with the first doped semiconductor layer 105; forming a second electrode 119, the second electrode 119 being embedded in the second passivation layer 128 and making an ohmic contact with the second doped semiconductor layer 106.

[0162] In some examples, an atomic layer deposition process and / or a plasma enhanced chemical vapor deposition process may be used to form the first passivation layer 118 and the second passivation layer 128. It should be noted that the second passivation layer 128 located on the first surface 101 and the first passivation layer 118 located on the second surface 102 may be formed synchronously.

[0163] In some examples, the step of forming the first electrode 109 may include: printing a metal paste on the surface of a part of the first passivation layer 118 away from the second surface 102 by means of a screen printing process; performing a sintering process on the metal paste. In some cases, the metal paste contains materials with highly corrosive components such as glass. Thus, during the sintering process, the corrosive components will at least corrode the first passivation layer 118, so that the metal paste penetrates from the first passivation layer 118 to the first doped semiconductor layer 105 to form the first electrode 109. It should be noted that the step of forming the second electrode 119 is similar to the step of forming the first electrode 109, and reference may be made to the above description of the step of forming the first electrode 109.

[0164] In some cases, the metal paste may include at least one of silver, lead, copper, tin, gold, lead or nickel.

[0165] It should be noted that in the manufacturing method provided by another embodiment of the present disclosure, there are no restrictions on the formation processes of the first passivation layer 118, the second passivation layer 128, the first electrode 109, and the second electrode 119. In practical applications, different formation processes can be selected according to requirements.

[0166] In summary, based on the design in step S2 that along the direction from the center to the edge of the laser spot, the energy of the laser spot first remains unchanged, then gradually increases, and finally gradually decreases to zero, it is beneficial to make the thickness of the damaged layer 104 formed in step S2 different in some different regions or the degree of internal damage different. On this basis, in step S3, the time consumed by the first texturing treatment to remove the damaged layer 104 in different regions is different, so the first texturing treatment will expose the initial substrate 110 covered by some different regions in the damaged layer 104 at different times, so as to texture some regions of the remaining initial substrate 110 at different times. Therefore, it is beneficial to form the groove 151 jointly surrounded by the bottom surface 131, the inclined surface 161, and the stepped surface 171, and different texture structures are formed only on the bottom surface 131 and the stepped surface 171.

[0167] Another embodiment of the present disclosure further provides a photovoltaic module, which is used to convert the received light energy into electrical energy. Hereinafter, the photovoltaic module provided by another embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that the same or corresponding parts as those in the foregoing embodiments will not be elaborated here.

[0168] With reference to Figures 1 to 6 and Figure 13 and Figure 14 the photovoltaic module includes: a battery string, which is formed by connecting a plurality of photovoltaic cells 40 provided in the foregoing embodiments, or photovoltaic cells 40 formed by the manufacturing method of a plurality of photovoltaic cells provided in the foregoing embodiments; an encapsulation film 41, which is used to cover the surface of the battery string; and a cover plate 42, which is used to cover the surface of the encapsulation film 41 facing away from the battery string. The photovoltaic cells 40 are electrically connected in a whole piece or in multiple sub-pieces to form a plurality of battery strings, and the plurality of battery strings are electrically connected in series and / or in parallel.

[0169] Among them, Figure 13 is a partial three-dimensional structure schematic diagram of a photovoltaic module provided by another embodiment of the present disclosure; Figure 14 is Figure 13 a cross-sectional structure schematic diagram along the cross-section direction MM1.

[0170] In some embodiments, the photovoltaic cell 40 includes, but is not limited to, a PERC cell (Passivated Emitter Rear Cell), an IBC cell (Interdigitated Back Contact), a TOPCon cell (Tunnel Oxide Passivated Contact), a HIT / HJT cell (Heterojunction Technology), a thin-film solar cell, or any combination of stacked cells. Among them, the thin-film solar cell includes, but is not limited to, a perovskite thin-film solar cell, a copper indium selenide thin-film solar cell, a gallium arsenide thin-film solar cell, and a cadmium sulfide thin-film solar cell. The stacked cell includes, but is not limited to, a perovskite cell stacked with a crystalline silicon cell, a perovskite cell stacked with a perovskite cell, and a perovskite cell stacked with a thin-film cell.

[0171] In some embodiments, the photovoltaic cell 40 can be a monocrystalline silicon solar cell, a polycrystalline silicon solar cell, an amorphous silicon solar cell, or a multi-component compound solar cell. Specifically, the multi-component compound solar cell can be a cadmium sulfide solar cell, a gallium arsenide solar cell, a copper indium selenide solar cell, or a perovskite solar cell. In addition, the photovoltaic cell 40 can be a whole-cell or a sliced cell. The sliced cell refers to a cell formed by cutting a complete whole-cell through a cutting process.

[0172] In some embodiments, referring to Figure 14 , multiple cell strings can be electrically connected through the conductive band 402. Figure 14 Only the positional relationship between one type of photovoltaic cells is schematically shown, that is, the arrangement directions of the electrodes with the same polarity of the cell wafers are the same, or in other words, the electrodes with the positive-polarity of each cell wafer are arranged on the same side, so that the conductive bands are respectively connected to different sides of two adjacent cell wafers. In some embodiments, the cell wafers can also have the electrodes with different polarities facing the same side, that is, the electrodes of adjacent multiple cell wafers are sequentially arranged in the order of the first polarity, the second polarity, and the first polarity, then the conductive bands connect two adjacent cell wafers on the same side.

[0173] In some embodiments, no gap is provided between the cell wafers, that is, the cell wafers overlap each other.

[0174] In some embodiments, the encapsulation film 41 includes a first encapsulation layer and a second encapsulation layer. The first encapsulation layer covers one of the front or back surfaces of the photovoltaic cell 40, and the second encapsulation layer covers the other of the front or back surfaces of the photovoltaic cell 40. Specifically, at least one of the first encapsulation layer or the second encapsulation layer may be an organic encapsulation film such as a polyvinyl butyral (PVB) film, an ethylene-vinyl acetate copolymer (EVA) film, a polyethylene octene elastomer (POE) film, or a polyethylene terephthalate (PET) film. Alternatively, at least one of the first encapsulation layer or the second encapsulation layer may also be a film such as an EP film, an EPE film, or a PVP film. Among them, the EP film refers to a co-extruded film composed of an EVA film and a POE film stacked, the EPE film refers to a co-extruded film formed by sequentially stacking an EVA film + a POE film + an EVA film, and the PVP film refers to a co-extruded film formed by stacking a POE film + an EVA film + a POE film. The method of preparing the co-extruded film may be to extrude one or more raw materials onto another film that has been made in sequence during the film processing, or to bond different types of films that have been made together.

[0175] In some cases, there is a demarcation line between the first encapsulation layer and the second encapsulation layer before lamination. After the lamination process, there will no longer be the concept of the first encapsulation layer and the second encapsulation layer in the formed photovoltaic module, that is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film 41.

[0176] In some embodiments, the cover plate 42 may be a cover plate with a light-transmitting function such as a glass cover plate or a plastic cover plate. Specifically, the surface of the cover plate 42 facing the encapsulation film 41 may be a concave-convex surface or a suede surface including a plurality of protruding structures, so as to increase the utilization rate of incident light. The cover plate 42 includes a first cover plate and a second cover plate. The first cover plate is opposite to the first encapsulation layer, and the second cover plate is opposite to the second encapsulation layer.

[0177] In some embodiments, the photovoltaic cell 40 may be a cell with main grids or a cell without main grids.

[0178] Those of ordinary skill in the art can understand that the above embodiments are specific embodiments for implementing the present disclosure. In actual applications, various changes can be made to them in form and details without departing from the spirit and scope of the embodiments of the present disclosure. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of the present disclosure. Therefore, the protection scope of the embodiments of the present disclosure should be subject to the scope defined by the claims.

Claims

1. A photovoltaic cell, characterized in that: include: A substrate, the substrate having a first surface and a second surface opposite to each other, the first surface having first areas and second areas alternately arranged along a first direction; The base located in the second area includes a bottom surface recessed into the base, at least two inclined surfaces connecting the bottom surface and the first area, and a step surface connecting adjacent inclined surfaces, wherein the bottom surface, the inclined surfaces and the step surfaces together form a groove, and the inclined surface is inclined toward the direction of the second area approaching the first area; The bottom surface is a first velvet surface including a plurality of first pyramids, and the step surface is a second velvet surface including a plurality of second pyramids, wherein the base size of the first pyramid is larger than the base size of the second pyramid, and the height of the first pyramid is larger than the height of the second pyramid.

2. The photovoltaic cell according to claim 1, characterized in that: In the same groove, multiple inclined surfaces and the step surface connecting adjacent inclined surfaces together constitute a slope, the orthographic projection area of ​​the slope on the bottom surface is the first area, the area of ​​the bottom surface is the second area, and the ratio of the first area to the second area is 0.005 to 0.

02.

3. The photovoltaic cell according to claim 1, characterized in that: The substrate located in the second zone includes two inclined surfaces and one step surface connecting adjacent inclined surfaces. Along the second direction, the distance between the step surface and the first zone is a first distance, and the distance between the step surface and the bottom surface is a second distance. The ratio of the first distance to the second distance is 0.6 to 1.3, and the second direction is the thickness direction of the substrate.

4. The photovoltaic cell according to claim 1, characterized in that: The inclined surface is inclined at an angle of 40° to 55° in a direction in which the second area is close to the first area.

5. The photovoltaic cell according to claim 1, characterized in that: The first zone is a third velvet surface including a plurality of third pyramids, wherein the base size of the third pyramids is larger than the base size of the second pyramids and smaller than the base size of the first pyramids; and / or, the height of the third pyramids is larger than the height of the second pyramids and smaller than the height of the first pyramids.

6. The photovoltaic cell according to claim 1, characterized in that: Also includes: The first protective layer covers the bottom surface, the inclined surface and the step surface.

7. The photovoltaic cell according to claim 6, characterized in that: The material of the first protection layer includes a semiconductor material doped with a doping element, silicon oxide, phosphosilicate glass or borosilicate glass.

8. A method for manufacturing a photovoltaic cell, characterized in that: include Providing an initial substrate, wherein the initial substrate has an initial first surface and an initial second surface opposite to each other, wherein the initial first surface has initial first regions and initial second regions alternately arranged along a first direction; The initial second area is irradiated with a laser spot with a gradually changing energy, so as to transform the initial substrate of a part of the thickness located in the initial second area into a damaged layer, and the energy change of the laser spot in the direction from the center of the laser spot to the edge at least includes a first stage, a second stage and a third stage connected in sequence, the energy of the laser spot is at a first preset value in the first stage, the energy of the laser spot gradually increases from the first preset value to a second preset value in the second stage, and the energy of the laser spot gradually decreases from the second preset value to zero in the third stage; The initial second area is subjected to a first texturing treatment to at least remove the damaged layer and form a groove in the initial second area, the remaining initial base is a base, the initial first area is transformed into a first area of ​​the base, the initial second area is transformed into a second area of ​​the base, the base located in the second area includes a bottom surface recessed into the base, at least two inclined surfaces connecting the bottom surface and the first area, and a step surface connecting adjacent inclined surfaces, The bottom surface, the inclined surface and the step surface together form the groove, and the inclined surface is inclined toward the first area; wherein the bottom surface is a first velvet surface including a plurality of first pyramids, and the step surface is a second velvet surface including a plurality of second pyramids, wherein the base size of the first pyramid is larger than the base size of the second pyramid, and the height of the first pyramid is larger than the height of the second pyramid.

9. The method for manufacturing a photovoltaic cell according to claim 8, characterized in that: The energy of the laser spot is the radiant illumination of the laser spot. In the direction from the center of the laser spot to the edge, the increase in the radiant illumination of the laser spot per 1 μm distance in the second stage is 0.008 J / mm 2 ~0.038J / mm 2 In the third stage, the radiation intensity of the laser spot decreases by 0.004 J / mm per 1 μm distance. 2 ~0.02J / mm 2 ; and / or, the first preset value is 0.01J / mm 2 ~0.02J / mm 2 The second preset value is 0.1J / mm 2 ~0.2J / mm 2 .

10. The method for manufacturing a photovoltaic cell according to claim 8, characterized in that: The first etching solution used in the first texturing treatment includes potassium hydroxide and water, and the ratio of potassium hydroxide to water is 0.002-0.01:1; and / or, the treatment time of the first texturing treatment is 200s-300s; and / or, the process temperature of the first texturing treatment is 65℃-75℃.

11. The method for manufacturing a photovoltaic cell according to claim 8, characterized in that: Also includes: Performing a high temperature treatment or a high temperature doping treatment on the groove to form a first protective layer covering the bottom surface, the inclined surface and the step surface; forming a first doped semiconductor layer on the second surface, wherein the first doped semiconductor layer is also located on a partial area of ​​the first surface; The first protective layer is used as an etching stop layer to etch the first doped semiconductor layer located on the first surface.

12. The method for manufacturing a photovoltaic cell according to claim 11, characterized in that: The process temperature of the high temperature treatment or the high temperature doping treatment is 900° C. to 1050° C., and the treatment time is 2000s to 5000s.

13. The method for manufacturing a photovoltaic cell according to claim 8, characterized in that: After providing the initial substrate and before irradiating the initial second area with the laser spot with gradually changing energy, the method for manufacturing the photovoltaic cell further includes: Performing a second texturing process on the initial first surface so that the initial first surface includes a plurality of third pyramids; Performing a doping treatment on the initial first surface so that a portion of the thickness of the initial substrate is transformed into a second doped semiconductor layer, and forming a second protective layer on a side of the second doped semiconductor layer away from the initial substrate; In the step of performing the first texturing treatment on the initial second area, the second protective layer is used as an etching barrier layer, the second doped semiconductor layer located in the initial first area is retained, and the initial first area is made into a third texturing surface including a plurality of the third pyramids, and the base size of the third pyramid is smaller than the base size of the second pyramid.

14. A photovoltaic module, characterized in that: include: A cell string formed by connecting a plurality of photovoltaic cells according to any one of claims 1 to 7, or by connecting a plurality of photovoltaic cells formed by the method for manufacturing a photovoltaic cell according to any one of claims 8 to 13; A packaging film, used to cover the surface of the battery string; The cover plate is used to cover the surface of the packaging film facing away from the battery string.

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