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 in the second area comprises a bottom surface which is recessed towards the interior of the substrate and a slope which is connected with the bottom surface and the first area, the slope inclines towards the first area, and the bottom surface and the slope define a groove; the bottom surface is a first suede comprising a plurality of first pyramids, the slope is a second suede comprising a plurality of second pyramids, an included angle formed by spire of the first pyramids is smaller than an included angle formed by spire of the second pyramids, and the height of the first pyramids is smaller than that of the second pyramids. The embodiment of the invention is at least beneficial to improving the absorption and utilization rate of the second region on light, so as to improve the photoelectric conversion efficiency of the photovoltaic cell.

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 region facing the electrode and the region 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 methods of the stepped structure and the specific morphologies of the stepped structure, the light absorption and utilization efficiency of the stepped structure will be affected. To further improve the photoelectric conversion efficiency of the photovoltaic cell, it is necessary to further study how to design a stepped structure with a lower reflectivity. 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 absorption and utilization efficiency of the second region, so as to improve the photoelectric conversion efficiency of the photovoltaic cell.

[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 and a slope connecting the bottom surface and the first region, the slope inclining towards the first region, and the bottom surface and the slope enclose a groove; the bottom surface is a first velvet surface including a plurality of first pyramids, the slope is a second velvet surface including a plurality of second pyramids, wherein the included angle formed by the tips of the first pyramids is smaller than the included angle formed by the tips of the second pyramids, and the height of the first pyramids is smaller than the height of the second pyramids.

[0007] In some embodiments, the tips of some of the second pyramids have pits.

[0008] In some embodiments, the ratio of the volume of the pit to the volume of the second pyramid having the pit is 0.01 to 0.2.

[0009] In some embodiments, in the same groove, along the first direction, the length of the bottom surface is a first length, the length of the slope is a second length, and the ratio of the second length to the first length is 0.001 to 0.01.

[0010] In some embodiments, the inclination angle of the slope inclined towards the first region is 40° to 55°.

[0011] In some embodiments, the first region is a third suede surface including a plurality of third pyramids, and the base size of the third pyramid is smaller than the base sizes of the second pyramid and the first pyramid; and / or, the tower height of the second pyramid is smaller than the tower heights of the first pyramid and the third pyramid; and / or, the reflectivity of the second suede surface is smaller than the reflectivities of the first suede surface and the third suede surface.

[0012] In some embodiments, the photovoltaic cell further includes: a first protective layer covering the bottom surface and the slope.

[0013] 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.

[0014] 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 having opposite initial first and second surfaces, the initial first surface having initial first and second regions arranged alternately in a first direction; irradiating the initial second region with a laser spot having a gradually changing energy to convert a partial 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 process on the initial second region to at least remove the damaged layer and form a groove in the second region, and the remaining initial substrate is the substrate, the initial first region is converted into the first region of the substrate, and the initial second region is converted into the second region of the substrate. The substrate located in the second region includes a bottom surface recessed into the substrate and a slope connecting the bottom surface and the first region, the slope inclines towards the first region, and the bottom surface and the slope enclose the groove; wherein, the bottom surface is a first textured surface including a plurality of first pyramids, the slope is a second textured surface including a plurality of second pyramids, the included angle formed by the tips of the first pyramids is smaller than the included angle formed by the tips of the second pyramids, and the height of the first pyramids is smaller than the height of the second pyramids.

[0015] 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 0.016 J / mm 2 ~0.19 J / mm 2 ; the decrease amount of the irradiance of the laser spot per 1 μm distance in the third stage is 0.01 J / mm 2 ~0.04 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 .

[0016] 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.

[0017] 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 and the slope; 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.

[0018] 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.

[0019] 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 convert 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.

[0020] According to some embodiments of the present disclosure, on the other hand, the present disclosure also provides a photovoltaic module, including: a battery string connected by 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.

[0021] The technical solutions provided by the embodiments of the present disclosure have at least the following advantages:

[0022] Differentially design the surface topographies of the bottom surface and the slope that enclose the groove. Specifically, design the bottom surface as the first suede surface and the slope as the second suede surface. Compared with the tower height of the first pyramid included in the first suede surface, the tower height of the second pyramid included in the second suede surface is smaller. On the one hand, the second pyramid with a lower tower height is beneficial to more evenly distribute the incident light on the slope, avoiding too high or too low local light intensity in the slope, so as to improve the photoelectric conversion efficiency of the photovoltaic cell under low-light conditions or oblique-incidence light conditions; on the other hand, the second pyramid with a lower tower height is beneficial to reducing the scattering path of light on the slope, so as to increase the absorption rate of the slope for short-wavelength light, such as blue light and ultraviolet light; on the other hand, the second pyramid with a lower tower height is beneficial to reducing the transmission distance of photo-generated carriers in the slope, thereby being beneficial to reducing the recombination probability of carriers, so as to improve the photoelectric conversion efficiency of the photovoltaic cell; on the other hand, as a transition zone between the bottom surface and the first region, designing the second pyramid on the slope is beneficial to avoiding the slope from being too steep, so that the entire groove can receive more incident-angle light, reducing light escape, so as to further reduce the reflection loss of light on the groove. In other words, by differentially designing the surface topographies of the bottom surface and the slope, it is beneficial to reduce the reflection loss of light on the second region, strengthen the light absorption and utilization rate of the second region, thereby improving the short-circuit current and photoelectric conversion efficiency of the photovoltaic cell. Moreover, it is beneficial to gradually transition the topography of the first surface from the higher first region to the lower bottom surface by reducing the steepness of the slope, which is beneficial to forming a film layer with a uniform thickness on the first surface subsequently. Brief Description of the Drawings

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

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

[0025] Figure 2 is Figure 1 The first enlarged schematic diagram of the area A within the dashed box in the shown structure;

[0026] Figure 3 is Figure 1 The second enlarged schematic diagram of the area A within the dashed box in the shown structure;

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

[0028] Figure 5 For Figure 1 The third enlarged schematic diagram at the dashed box A in the structure shown;

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

[0030] Figure 7 The third partial cross-sectional schematic diagram of a photovoltaic cell provided by an embodiment of the present disclosure;

[0031] Figure 8 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;

[0032] Figure 9 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;

[0033] Figure 10 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;

[0034] Figure 11 For Figure 6 A partial cross-sectional schematic diagram after forming a first doped semiconductor layer on the basis of the structure shown;

[0035] Figure 12 For Figure 11 A partial cross-sectional schematic diagram after etching treatment on the basis of the structure shown;

[0036] Figure 13 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;

[0037] Figure 14 A partial three-dimensional structural schematic diagram of a photovoltaic module provided by still another embodiment of the present disclosure;

[0038] Figure 15 For Figure 14 A cross-sectional structural schematic diagram along the cross-sectional direction MM1. Detailed implementation manners

[0039] As can be seen from the background art, the light absorption utilization rate of photovoltaic cells needs to be improved, and the photoelectric conversion efficiency of photovoltaic cells needs to be improved.

[0040] Embodiments of the present disclosure provide a photovoltaic cell, a manufacturing method thereof, and a photovoltaic module. In the photovoltaic cell, the surface morphologies of the bottom surface and the slope that enclose the groove are designed differently. Specifically, the bottom surface is designed as a first matte surface, and the slope is designed as a second matte surface. Compared with the height of the first pyramid included in the first matte surface, the height of the second pyramid included in the second matte surface is smaller. On the one hand, the second pyramid with a lower height is beneficial for more uniformly distributing the incident light on the slope, avoiding too high or too low local light intensity in the slope, so as to improve the photoelectric conversion efficiency of the photovoltaic cell under low-light conditions or oblique-incidence light conditions. On the other hand, the second pyramid with a lower height is beneficial for reducing the scattering path of light on the slope, so as to improve the absorption rate of the slope for short-wavelength light, such as blue light and ultraviolet light. On the other hand, the second pyramid with a lower height is beneficial for reducing the transmission distance of photo-generated carriers in the slope, thereby being beneficial for reducing the recombination probability of carriers, so as to improve the photoelectric conversion efficiency of the photovoltaic cell. On the other hand, as a transition area between the bottom surface and the first area, designing the second pyramid on the slope is beneficial for avoiding the slope from being too steep, so that the entire groove can receive more incident-angle light, reducing light escape, so as to further reduce the reflection loss of light on the groove. In other words, by designing the surface morphologies of the bottom surface and the slope differently, it is beneficial for reducing the reflection loss of light on the second area, strengthening the absorption and utilization rate of light in the second area, thereby improving the short-circuit current and photoelectric conversion efficiency of the photovoltaic cell. Moreover, it is beneficial for making the morphology of the first surface gradually transition from the higher first area to the lower bottom surface by reducing the steepness of the slope, which is beneficial for subsequently forming a film layer with a uniform thickness on the first surface.

[0041] 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 indicating 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" is more than two, unless otherwise clearly and specifically defined.

[0042] Referring to "embodiments" herein means that the specific features, structures or characteristics described in connection with the embodiments 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. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0043] In the description of the embodiments of the present disclosure, the term "and / or" is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: there is A, there is both A and B, and there is B. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0044] In the description of the embodiments of the present disclosure, the term "plurality" means two or more (including two). Similarly, "multiple groups" means two or more groups (including two groups), and "multiple pieces" means two or more pieces (including two pieces).

[0045] In the description of the embodiments of the present disclosure, the orientation or positional relationship indicated by technical terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the embodiments of the present disclosure.

[0046] 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 it 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.

[0047] In the corresponding drawings of the embodiments of the present disclosure, for better understanding and convenience of description, the thickness and area of the layer are enlarged. When describing a component (such as a layer, a film, a region, or a substrate) 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. On the contrary, when describing a component on the surface of another component or when another component is formed or provided on the surface of a component, it means that there is no third component between the two components. In addition, when describing a component "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.

[0048] In the description of the embodiments of the present disclosure, when a component "includes" another component, unless otherwise stated, other components are not excluded, and other components may further be included. In addition, when a component such as a layer, film, region, or plate is referred to as being "on / located on" another component, it may be "directly on" the other component (i.e., located on the surface of the other component with no other components therebetween), or there may be other components therebetween. In addition, when a component such as a layer, film, region, or plate is "directly located on" another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it means that no other components are located therebetween.

[0049] The terms used in the description of the various embodiments herein are only for the purpose of 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 a layer, film, region, or plate.

[0050] The embodiments of the present disclosure will be described in detail below with reference to 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 presented for the reader 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 be implemented.

[0051] An embodiment of the present disclosure provides a photovoltaic cell, and the photovoltaic cell provided by an embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0052] With reference to 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, and a slope 141 connecting the bottom surface 131 and the first region 111, the slope 141 being inclined toward the first region 111, and the bottom surface 131 and the slope 141 enclosing a groove 151; the bottom surface 131 is a first matte surface including a plurality of first pyramids 131a, the slope 141 is a second matte surface including a plurality of second pyramids 141a, wherein the tower height of the first pyramids 131a is greater than the tower height of the second pyramids 141a.

[0053] Among them, 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 of the dashed box A in the structure shown; Figure 3 isFigure 1 The second enlarged schematic view at the dashed box A in the shown structure; Figure 4 A three-dimensional scanning electron microscope schematic view of a substrate in a photovoltaic cell provided by an embodiment of the present disclosure.

[0054] It should be noted that the surface morphologies of the bottom surface 131 and the slope 141 enclosing the groove 151 are designed differently. Specifically, the bottom surface 131 is designed as a first matte surface, and the slope 141 is designed as a second matte surface. Compared with the tower height of the first pyramid 131a included in the first matte surface, the tower height of the second pyramid 141a included in the second matte surface is smaller. On the one hand, the second pyramid 141a with a lower tower height is beneficial for more uniformly distributing the incident light on the slope 141, avoiding too high or too low local light intensity in the slope 141, improving the overall light absorption utilization rate of the slope 141, reducing light escape, further reducing the reflection loss of light on the slope 141, and improving the photoelectric conversion efficiency of the photovoltaic cell under low-light conditions or oblique-incidence light conditions. On the other hand, the second pyramid 141a with a lower tower height is beneficial for reducing the scattering path of light on the slope 141, so as to improve the absorption rate of the slope 141 for short-wavelength light, such as blue light and ultraviolet light. On the other hand, the second pyramid 141a with a lower tower height is beneficial for reducing the transmission distance of photo-generated carriers in the slope 141, thereby being beneficial for reducing the recombination probability of carriers and improving the photoelectric conversion efficiency of the photovoltaic cell. On the other hand, as a transition region between the bottom surface 131 and the first region 111, designing the second pyramid 141a on the slope 141 is beneficial for avoiding the slope 141 from being too steep, so that the opening area of the groove 151 in the cross-section parallel to the second surface 102 gradually increases along the second direction Y. Then, the whole groove 151 can receive more incident-angle light, reduce light escape, and further reduce the reflection loss of light on the groove 151. The second direction Y is the direction from the second surface 102 to the first surface 101.

[0055] In other words, compared with the current step structure formed by a single film opening, the side wall is relatively steep, and the surface morphology of the side wall is not easy to control, so that the incident angle of the incident light that the side wall can receive is very limited, and the difference in the light absorption utilization rate of the side wall at different light illumination angles is very large, which is not conducive to the overall light absorption utilization rate of the photovoltaic cell. In the photovoltaic cell provided by an embodiment of the present disclosure, by designing the surface morphologies of the bottom surface 131 and the slope 141 differently, it is beneficial to reduce the reflection loss of light on the second region 121, strengthen the light absorption utilization rate of the second region 121, and thus improve the short-circuit current and photoelectric conversion efficiency of the photovoltaic cell. Moreover, it is beneficial to gradually transition the morphology of the first surface 101 from the relatively high first region 111 to the relatively low bottom surface 131 by reducing the steepness of the slope 141, which is beneficial for subsequently forming a film layer with a uniform thickness on the first surface 101.

[0056] In some cases, based on the design of the surface topography of the bottom surface 131 and the slope 141 that enclose the groove 151, it is beneficial to reduce the overall light reflectivity of the second region 121 to about 10.8.

[0057] In some cases, the slope 141 being inclined towards the first region 111 means that the slope 141 can be inclined towards the direction in which the second region 121 approaches the first region 111.

[0058] It should be emphasized that the photovoltaic cell further includes at least an electrode located on the first surface 101, and the electrode is used to extract the photo-generated carriers generated in the substrate 100. Based on this, for the convenience of explaining the specific orientation of the first pyramid 131a and the second pyramid 141a on the first surface 101, for those skilled in the art, the first surface 101 can 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 large 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 can 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 can be located in the interval between adjacent second regions 121, and the second region 121 can also be located in the interval between adjacent first regions 111.

[0059] Furthermore, to further reflect the difference between the first pyramid 131a and the second pyramid 141a, for those skilled in the art, the second region 121 can be divided into 1 transition region 122, 1 second sub-region 123, and another 1 transition region 122 arranged in sequence along the first direction X. Among them, 1 transition region 122 is used to refer to the region occupied by one slope 141 on the second region 121, and 1 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 141a is located in the transition region 122. In addition, the 2 first regions 111 located on the opposite sides of the same second region 121 along the first direction X are respectively connected to 1 transition region 122.

[0060] The following will describe an embodiment of the present disclosure in more detail with reference to the drawings.

[0061] In some embodiments, with reference to Figure 4 and Figure 5 ,Figure 5 For Figure 1 the third enlarged schematic view at the dashed box A in the structure shown, the tips of some of the second pyramids 141a have pits 141b. In this way, the roughness of the surface of the second pyramid 141a can be increased by means of the pits 141b, so that the light incident into the pits 141b of the second pyramid 141a has more reflection angles or refraction angles, prompting the light to be more easily absorbed and utilized by the second pyramid 141a under the enclosure of the pits 141b after multiple reflections or refractions, so as to further reduce the probability of the light being reflected outside the second pyramid 141a, which is beneficial to further enhancing the light trapping effect of the second pyramid 141a and further improving the photoelectric conversion efficiency of the photovoltaic cell.

[0062] It should be noted that for the second pyramid 141a without the pits 141b, referring to Figure 3 or Figure 5 , the second pyramid 141a can be regarded as a quadrangular pyramid surrounded by 4 side edges sharing a vertex and 4 side faces connecting adjacent side edges; for the second pyramid 141a with the pits 141b, referring to Figure 5 , the second pyramid 141a can be regarded as the above-mentioned quadrangular pyramid with pits 141b at the tip, and the quadrangular pyramid with pits 141b at the tip is regarded as a quasi-quadrangular pyramid. In other words, due to the existence of the pits 141b, the endpoints of multiple side edges will not converge to the same vertex, but the extension directions of multiple side edges can converge to the same vertex. In addition, only the tips of some of the second pyramids 141a have pits 141b, and not the tip of any second pyramid 141a has pits 141b.

[0063] In some examples, referring to Figure 4 and Figure 5 , the ratio of the volume of the pit 141b to the volume of the second pyramid 141a with the pit 141b is 0.01 - 0.2. For example, it can be 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18 or 0.19, etc.

[0064] If the ratio of the volume of the pit 141b to the volume of the second pyramid 141a having the pit 141b is less than 0.01, the pit 141b is too small compared to the second pyramid 141a, which will limit the incident angle of the light that the pit 141b can receive and is not conducive to improving the light trapping effect. If the ratio of the volume of the pit 141b to the volume of the second pyramid 141a having the pit 141b is greater than 0.2, the pit 141b is too large compared to the second pyramid 141a, which will significantly reduce the area of the side surface of the second pyramid 141a and is not conducive to the uniform deposition of the subsequent film layer on the slope 141. Therefore, the ratio of the volume of the pit 141b to the volume of the second pyramid 141a having the pit 141b is designed to be 0.01 - 0.2, which is not only conducive to ensuring that the pit 141b has a better light trapping effect, but also conducive to reducing the surface roughness of the overall slope 141 of the second matte surface, so as to facilitate the uniform deposition of the subsequent film layer on the slope 141.

[0065] It should be noted that due to the influence of the manufacturing process for forming the second pyramid 141a, the fluctuation range of the ratio of the volume of the pit 141b to the volume of the second pyramid 141a having the pit 141b is relatively large, and the manufacturing process of the second pyramid 141a will be described in detail later. In addition, for the second pyramid 141a, the volume of the pit 141b is small, so that the overall appearance of the second pyramid 141a still shows an obvious pyramid structure and will not affect the stability of the structure of the second pyramid 141a.

[0066] In some embodiments, referring to Figure 2 、 Figure 3 or Figure 5 , in the same groove 151, along the first direction X, the length of the bottom surface 131 is the first length L1, and the length of the slope 141 is the second length L2. The ratio of the second length L2 to the first length L1 can be 0.001 - 0.01. For example, it can be 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008 or 0.009, etc.

[0067] It should be noted that both the first region 111 and the second region 121 extend along the third direction. Then, the groove 151 can be regarded as a long groove extending along the third direction. The extension dimensions of both the bottom surface 131 and the slope 141 in the third direction are the same. The area sizes of both the bottom surface 131 and the slope 141 mainly depend on the lengths of the bottom surface 131 and the slope 141 in the first direction X. Based on this, when the ratio of the second length L2 to the first length L1 is designed to be 0.001 - 0.01, the surface area of the groove 151 is mainly determined by the area of the bottom surface 131. Designing the height of the first pyramid 131a included in the bottom surface 131 to be higher 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 evenly, thereby helping to reduce defects and pores in the film layer and improve the quality and performance of the film layer.

[0068] In some cases, referring to Figure 2 、 Figure 3 or Figure 5 , along the first direction X, the first length L1 of the bottom surface 131 can be 200 μm - 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.

[0069] In some embodiments, referring to Figure 2 、 Figure 3 or Figure 5 , the inclination angle α of the slope 141 inclined towards the first region 111 can be 40° - 55°. For example, the inclination angle α 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 slopes 141 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 slope 141 inclined towards the first region 111 can be 40° - 55°.

[0070] It should be noted that the inclination angle α of the designed slope 141 inclined towards the first region 111 is 40° to 55°. On the one hand, it can prevent the slope 141 from being too steep. As a transition region between the bottom surface 131 and the first region 111, the slope 141 is conducive to reducing the height difference between different regions on the slope 141. In other words, with the second surface 102 as the reference plane, it is beneficial to reduce the height difference between adjacent different regions along the first direction X in the slope 141, enabling the topography of the first surface 101 to gradually transition from the higher first region 111 to the lower bottom surface 131, thus facilitating the subsequent formation of a film layer with a uniform thickness, such as a passivation film layer, on the first surface 101, and thereby improving the passivation effect of the passivation film layer. On the other hand, it makes the slope 141 relatively gentle with respect to the first region 111, facilitating the design of the second pyramid 141a on the slope 141.

[0071] Moreover, referring to Figure 2 , Figure 3 or Figure 5 , the second region 121 can be regarded as including 1 transition region 122, 1 second sub-region 123, and another 1 transition region 122 arranged in sequence along the first direction X. Among them, 1 transition region 122 is used to refer to the region occupied by a slope 141 on the first surface 101, and 1 second sub-region 123 is used to refer to the region occupied by a bottom surface 131 on the first surface 101. Based on this, designing the inclination angle α of the slope 141 inclined towards the first region 111 to be 40° to 55° is beneficial to increasing the surface area of the slope 141 that can be arranged on the transition region 122 per unit distance along the first direction X, so as to increase the number of second pyramids 141a that can be arranged on the slope 141 per unit distance along the first direction X, and further improve the light trapping effect of the slope 141, that is, improve the absorption and utilization rate of light by the slope 141.

[0072] In addition, if the inclination angle α of the designed slope 141 inclined towards the first region 111 is less than 40°, in order to ensure a relatively large surface area of the slope 141, the size of the transition region 122 in the first direction X will be increased, thereby reducing the number of first regions 111 that can be arranged on the entire first surface 101. Therefore, designing the inclination angle α of the slope 141 inclined towards the first region 111 to be greater than or equal to 40° is beneficial to ensuring that the slope 141 has a surface for arranging a sufficient number of second pyramids 141a, while reducing the overall size of the slope 141 in the first direction X, that is, reducing the proportion of the transition region 122 in the entire first surface 101.

[0073] It should be noted that referring to Figure 2 , Figure 3 or Figure 5, the plane where the bottom surfaces of most of the second pyramids 141a included in the slope 141 are located is used as the reference plane of the slope 141, and the reference plane of the slope 141 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 used as the second reference plane. Based on this, the inclination angle α at which the slope 141 inclines towards the first area 111 refers to: the acute angle formed by the first reference plane of the slope 141 and the second reference plane of the bottom surface 131. In addition, Figure 2 、 Figure 3 or Figure 5 both schematically show the first reference plane of the slope 141 and the second reference plane of the bottom surface 131 with relatively dense dotted lines.

[0074] In addition, the bottom surface of the second pyramid 141a is the plane where the base of the second pyramid 141a is located, 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 patterns of the bases of both the first pyramid 131a and the second pyramid 141a on the base 100 can be regular quadrilaterals or irregular polygons.

[0075] It should be noted that the bottom surfaces of all the second pyramids 141a included in the slope 141 may be in different planes, but the bottom surfaces of more than half of the second pyramids 141a are almost in the same plane, and this plane can be used as the first reference plane. Similarly, 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 second reference plane.

[0076] In some embodiments, referring to Figure 2 、 Figure 3 or Figure 5 , along the second direction Y, the depth H1 of the groove 151 can be 4 μm to 6 μm. For example, it can be 4.1 μm, 4.2 μm, 4.3 μm, 4.4 μm, 4.5 μm, 4.6 μm, 4.7 μm, 4.8 μm, 4.9 μm, 5 μm, 5.1 μm, 5.2 μm, 5.3 μm, 5.4 μm, 5.5 μm, 5.6 μm, 5.7 μm, 5.8 μm or 5.9 μm, etc.

[0077] It should be noted that the plane where the tips of most of the first pyramids 131a are located is taken as the first plane. Along the second direction Y, the depth H1 of the groove 151 refers to the distance between the first plane and the plane where the first region 111 is located. The plane where the first region 111 is located will be described in detail later. In addition, the tips of all the first pyramids 131a included in the bottom surface 131 may be in different planes, but the tips of more than half of the first pyramids 131a are almost in the same plane, and this plane can be used as the first plane.

[0078] In some cases, referring to Figure 3 or Figure 5 , the first region 111 is a third suede surface including a plurality of third pyramids 111a. The plane where the first region 111 is located can be the plane where the tips of most of the third pyramids 111a are located. The plane where the tips of most of the third pyramids 111a are located is taken as the second plane. Along the second direction Y, the depth H1 of the groove 151 refers to the distance between the first plane and the second plane. It should be noted that the tips of all the third pyramids 111a included in the first region 111 may be in different planes, but the tips of more than half of the third pyramids 111a are almost in the same plane, and this plane can be used as the second plane.

[0079] In some cases, referring to Figure 3 or Figure 5 , the first region 111 is a third suede 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, along the second direction Y, the distance H2 between the third reference plane of the first region 111 and the second reference plane of the bottom surface 131 can be 4.5 μm to 6.5 μm. For example, it can be 4.6 μm, 4.7 μm, 4.8 μm, 4.9 μm, 5 μm, 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 or 6.4 μm, etc.

[0080] It should be noted that Figure 3 and Figure 5 both schematically show the third reference plane of the first region 111 with a relatively dense dashed line.

[0081] In some embodiments, referring to Figure 3 or Figure 5, the first region 111 is a third matte surface including a plurality of third pyramids 111a. The size relationships among the first pyramid 131a, the second pyramid 141a, and the third pyramid 111a will be described in detail below.

[0082] In some cases, referring to Figure 3 or Figure 5 , the base size of the third pyramid 111a is smaller than the base sizes of the second pyramid 141a and the first pyramid 131a. In other words, the base size of the third pyramid 111a is the smallest.

[0083] 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 141a, and the third pyramid 111a.

[0084] 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 approximately 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 the multiple regions with different specific areas is obtained.

[0085] 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 sizes of both the second pyramid 141a and the first pyramid 131a 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.

[0086] In one example, the base of the third pyramid 111a can be a quadrilateral with a size of 1.5 μm * 1.5 μm, and the bases of both the second pyramid 141a and the first pyramid 131a can be quadrilaterals with a size of 2 μm * 2 μm.

[0087] In some cases, referring to Figure 3 or Figure 5 , the height of the second pyramid 141a is less than the heights of the first pyramid 131a and the third pyramid 111a. In other words, the height of the second pyramid 141a is the smallest.

[0088] It should be noted that the height of the pyramid refers to the distance between the apex of the pyramid and the base in the second direction Y.

[0089] In some examples, the height of the second pyramid 141a can be from 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 heights of both the first pyramid 131a and 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.

[0090] In some cases, referring to Figure 3 or Figure 5 , the reflectivity of the second textured surface is less than the reflectivities of the first textured surface and the third textured surface. In other words, the reflectivity of the slope 141 is less than the reflectivities of the bottom surface 131 and the first region 111, and the reflectivity of the slope 141 is the smallest.

[0091] In some examples, the reflectivity of the slope 141 can be 10 - 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 11.5 - 12.5. For example, it can be 11.6, 11.7, 11.8, 11.9, 12, 12.1, 12.2, 12.3, or 12.4, etc.; the reflectivity of the first region 111 can be 10.5 - 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.

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

[0093] In some embodiments, referring to Figure 3 or Figure 5 , the apex angles of the first pyramid 131a, the second pyramid 141a, and the third pyramid 111a can all be 65° - 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 by means of the pyramid with a smaller apex angle. For example, light with 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 opposite side edges in the pyramid can be regarded as the apex angle of the pyramid.

[0095] In some embodiments, referring to Figure 6 , Figure 6 is the second partial cross-sectional schematic diagram of the 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 and the slope 141.

[0096] In some cases, the first protective layer 103 can conformally cover the bottom surface 131 and the slope 141. Then, the surface topography of the part of the first protective layer 103 facing the bottom surface 131 also presents a velvet-like topography similar to that of the bottom surface 131, and the surface topography of the part of the first protective layer 103 facing the slope 141 also presents a velvet-like topography similar to that of the slope 141.

[0097] It is worth noting that in combination with reference to Figures 2 to 6, on the one hand, the first protective layer 103 is conducive to protecting the morphologies of the first pyramid 131a and the second pyramid 141a. 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 damaging the first pyramid 131a and the second pyramid 141a during the patterning process, thereby facilitating ensuring that the second region 121 has a low reflectivity.

[0098] , on the other hand, the first protective layer 103 is conducive 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.

[0099] 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.

[0100] In some embodiments, referring to Figure 6 , 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.

[0101] 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 can be in single crystal state, polycrystalline state, amorphous state, or microcrystalline state (the state with both single crystal state and amorphous state is called microcrystalline state). For example, silicon can 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 can 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.

[0102] 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).

[0103] In some embodiments, the material of the substrate 100 may be an elemental semiconductor material or a compound semiconductor material.

[0104] 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.

[0105] In some embodiments, refer to Figure 7 , Figure 7 FIG. 3 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 a 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 a side of the first doped semiconductor layer 105 away from the tunneling layer 108; a second passivation layer 128 located on a 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; and a second electrode 119 embedded in the second passivation layer 128 and in ohmic contact with the second doped semiconductor layer 106.

[0106] It should be noted that the second doped semiconductor layer 106, as a selective emitter structure on the first surface 101, is beneficial 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 the light incident on the second region 121 by the second doped semiconductor layer 106, improving the utilization rate of the incident light on the first surface 101, and improving the photoelectric conversion efficiency of the photovoltaic cell.

[0107] In addition, the tunneling layer 108 and the first doped semiconductor layer 105 together form a passivation 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 serve as an optical optimization layer for the second surface 102 to improve the light absorption and utilization rate of 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 serve as an optical optimization layer for the first surface 101 to improve the light absorption and utilization rate of the first surface 101.

[0108] 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 7 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 in the second region 121 towards the second surface 102 can be regarded as being composed of the second doped semiconductor layer 106 and the substrate 100 located in the first region 111 together.

[0109] 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.

[0110] In some cases, both the second passivation layer 128 and the first passivation layer 118 can be single-layer structures or stacked structures. 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.

[0111] In some cases, the substrate 100 may 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 may 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.

[0112] In summary, when the bottom surface 131 is designed as the first textured surface and the slope 141 is designed as the second textured surface, compared with the tower height of the first pyramid 131a included in the first textured surface, the tower height of the second pyramid 141a included in the second textured surface is smaller. On the one hand, the second pyramid 141a with a lower tower height is beneficial to more evenly distribute the incident light on the slope 141, avoid too high or too low local light intensity in the slope 141, improve the overall light absorption and 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-incidence light conditions. On the other hand, the second pyramid 141a with a lower tower height is beneficial to reducing the scattering path of light on the slope 141, so as to improve the absorption rate of the slope 141 for short-wavelength light, such as blue light and ultraviolet light. On the other hand, the second pyramid 141a with a lower tower height is beneficial to reducing the transmission distance of photo-generated carriers in the slope 141, thereby being beneficial to reducing the recombination probability of carriers and improving the photoelectric conversion efficiency of the photovoltaic cell. On the other hand, as a transition region between the bottom surface 131 and the first region 111, designing the second pyramid 141a on the slope 141 is beneficial to avoiding the slope 141 from being too steep, so that the opening area of the groove 151 in the cross-section parallel to the second surface 102 gradually increases along the second direction Y. Then, the overall groove 151 can receive more incident-angle light, reduce light escape, and further reduce the reflection loss of light on the groove 151.

[0113] Moreover, in the photovoltaic cell provided by an embodiment of the present disclosure, it is beneficial to gradually transition the topography of the first surface 101 from the relatively high first region 111 to the relatively low bottom surface 131 by reducing the steepness of the slope 141, which is beneficial to forming a film layer with a uniform thickness on the first surface 101 subsequently.

[0114] Another embodiment of the present disclosure further provides a manufacturing method of a photovoltaic cell for forming the photovoltaic cell provided by the foregoing embodiment. The following will detail the manufacturing method of the photovoltaic cell provided by another embodiment of the present disclosure with reference to the accompanying drawings. Figures 8 to 13 FIG. is a schematic partial cross-sectional structure diagram corresponding to each step in the manufacturing method of the photovoltaic cell provided by 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.

[0115] Combined reference Figures 8 to 13 Combined reference Figures 1 to 5 The manufacturing method of a photovoltaic cell may at least include the following steps:

[0116] S1: Reference Figure 8 Figure 8 FIG. 13 is a partial cross-sectional schematic view of an initial substrate provided in the manufacturing method of a photovoltaic cell according to 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.

[0117] It should be noted that the initial first surface 120 corresponds to the subsequently formed first surface, the initial first regions 140 correspond to the first regions of the subsequently formed first surface, the initial second regions 150 correspond to the second regions of the subsequently formed first surface, and the initial second surface 130 corresponds to the subsequently formed second surface.

[0118] S2: Combined reference Figures 8 to 10 Irradiate the initial second region 150 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.

[0119] It should be noted that Figure 9 FIG. 14 is a partial cross-sectional schematic view after forming a damaged layer in the manufacturing method of a photovoltaic cell according to another embodiment of the present disclosure; Figure 10 FIG. 15 is a curve graph corresponding to the energy gradient of the laser spot in the manufacturing method of a photovoltaic cell according to another embodiment of the present disclosure. In addition, Figure 10 the center of the laser spot is taken as the 0 point in FIG. 15.

[0120] S3: Combined reference Figure 9 and Figures 1 to 5 ​, a first texturing process is performed on the initial second region 150 to at least remove the damaged layer 104 and form grooves 151 in the initial second region 150. The remaining initial substrate 110 becomes 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 in the second region 121 includes a bottom surface 131 that is recessed into the substrate 100 and a slope 141 that connects the bottom surface 131 and the first region 111. The slope 141 slopes towards the first region 111, and the bottom surface 131 and the slope 141 enclose the groove 151.

[0121] Among them, the bottom surface 131 is a first textured surface including a plurality of first pyramids 131a, and the slope 141 is a second textured surface including a plurality of second pyramids 141a. The height of the first pyramids 131a is greater than the height of the second pyramids 141a.

[0122] 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 with grooves 151.

[0123] Further, based on the design in step S2, along the direction from the center of the laser spot to the edge, the energy of the laser spot first remains unchanged, then gradually increases, and finally gradually decreases to zero, which is beneficial to making the thickness of the damage layer 104 formed in step S2 different in 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 damage 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 damage layer 104 first remains unchanged, then gradually increases, and finally gradually decreases to zero. On this basis, in step S3, there will be differences in the etching rates of different regions of the damage layer 104 during the first texturing process, and there will also be differences in the time consumed for the first texturing process to remove different thicknesses of the damage layer 104. Then, the first texturing process will expose different parts of the initial substrate 110 covered by the damage layer 104 at different times, and further texture the remaining initial substrate 110 at different times. Therefore, it is beneficial to form the groove 151 jointly surrounded by the bottom surface 131 and the slope 141, and different textured surfaces are formed on the bottom surface 131 and the slope 141. Specifically, the bottom surface 131 forms the first textured surface including a plurality of first pyramids 131a, and the slope 141 forms the second textured surface including a plurality of second pyramids 141a.

[0124] In other words, under the combined action of the laser spot with gradually changing energy irradiating the initial second region 150 in step S2 and the first texturing process in step S3, the turning points of the etching rates of different regions of the film layer jointly composed of the damage layer 104 and the remaining initial substrate 110 are different along the direction from the center of the initial second region 150 to the initial first region 140. Further, the average etching rate of different regions of the film layer jointly composed of the damage layer 104 and the remaining initial substrate 110 gradually changes during the first texturing process, for example, first remains unchanged and then gradually decreases, which is beneficial to finally forming a slope 141 with a lower steepness.

[0125] In some embodiments, with reference to Figure 10 and Figure 2 、 Figure 3 and Figure 5 The maximum energy of the laser spot, that is, the second preset value, irradiates on the bottom surface 131 of the groove 151 and on the region of the bottom surface 131 close to the slope 141. 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 slopes 141 respectively.

[0126] In some cases, along the first direction X, the distance between the irradiated position of the bottom surface 131 corresponding to the second preset value and the junction of the slope 141 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.

[0127] It should be noted that the first length L1 of the bottom surface 131 is formed by multiple lasers parallelly opening the film. 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 irradiated position of the bottom surface 131 corresponding to the second preset value and the junction of the slope 141 and the bottom surface 131 is relatively small. In other words, the position irradiated by the turning point of the energy reduction of the laser spot is very close to the finally required slope 141.

[0128] In some examples, the preset distance D between the irradiated position of the bottom surface 131 corresponding to the second preset value and the junction of the slope 141 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.

[0129] In some examples, the overall size of the laser spot can be 50μm - 200μm. In other words, the diameter of the laser spot can be 50μm - 200μm. For example, it can be 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm or 190μm, etc.

[0130] In some examples, in combination with reference Figure 9 and Figure 10, the single laser spot is divided into two symmetric parts along the center. Along 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 area 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 area 150 can be 1 μm to 5 μm. For example, it can be 1.2 μm, 1.5 μm, 1.6 μm, 1.8 μm, 2 μm, 2.2 μm, 2.5 μm, 2.6 μm, 3 μm, 3.2 μm, 3.5 μm, 3.8 μm, 4 μm, 4.2 μm, 4.5 μm or 4.8 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 area 150 can be 5 μm to 20 μm. For example, it can be 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm or 19 μm, etc.

[0131] It should be noted that the width of the irradiation area of the laser spot corresponding to the second stage II on the initial second area 150 is designed to be 1 μm to 5 μm, and the width of the irradiation area of the laser spot corresponding to the third stage III on the initial second area 150 is designed to be 5 μm to 10 μm, so as to shorten the irradiation range of the laser spots corresponding to the second stage II and the third stage III on the initial second area 150, which is beneficial to controlling the lower damage degree inside the damage layer 104 corresponding to the finally formed slope 141, reducing the etching degree of the damage layer 104 corresponding to the finally formed slope 141 and the initial substrate 110 during the first texturing process, and promoting the formation of the slope 141 including the second pyramid 141a after the first texturing process.

[0132] In some embodiments, referring to Figure 10 , 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 amount of the irradiance of the laser spot per 1 μm distance in the second stage II can be 0.016 J / mm 2 ~0.19 J / mm 2 , and the decrease amount of the irradiance of the laser spot per 1 μm distance in the third stage III can be 0.01 J / mm 2 ~0.04 J / mm2 。

[0133] It should be noted that the growth rate of the irradiance of the laser spot in the second stage II of the design can be greater than the reduction 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, the growth rate of the irradiance of the laser spot in the second stage II of the design and the reduction rate of the irradiance of the laser spot in the third stage III are both relatively large, which is convenient for the first texturing process to form the first pyramid 131a in the bottom surface 131 and form the second pyramid 141a in the slope 141.

[0134] In some examples, along the direction from the center to the edge of the laser spot, the increase in the irradiance of the laser spot per 1 μm distance in the second stage II can be 0.017 J / mm 2 、0.02 J / mm 2 、0.03 J / mm 2 、0.04 J / mm 2 、0.05 J / mm 2 、0.06 J / mm 2 、0.07 J / mm 2 、0.08 J / mm 2 、0.09 J / mm 2 、0.1 J / mm 2 、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 or 0.18 J / mm 2 etc.

[0135] In some examples, along the direction from the center to the edge of the laser spot, the decrease in the irradiance of the laser spot per 1 μm distance in the third stage III 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 、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 / mm 2 , 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 , 0.037 J / mm 2 , 0.038 J / mm 2 or 0.039 J / mm 2 etc.

[0136] It should be noted that irradiance characterizes the amount of radiant energy received per unit area per unit time on the surface irradiated by radiant energy, that is, the radiant flux density on the irradiated surface.

[0137] In some embodiments, referring to Figure 10 , 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 2 etc.; 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.

[0138] In some embodiments, with reference to Figure 9 and Figures 1 to 5 , 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 may be 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, or 0.009, etc.

[0139] In some embodiments, the treatment duration of the first texturing treatment may be 200 s - 300 s. For example, it may 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.

[0140] In some embodiments, the process temperature of the first texturing treatment may be 65°C - 75°C. For example, it may be 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, or 74°C, etc.

[0141] In some embodiments, with reference to Figure 1 and Figure 6 , Figure 11 and Figure 12 , the manufacturing method of the photovoltaic cell may further include: with reference to Figure 1 and Figure 6 , 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 and the slope 141; with reference to Figure 6 and Figure 11 , 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 11 and Figure 12 , using the first protective layer 103 as an etching barrier layer, performing an etching treatment on the first doped semiconductor layer 105 located on the first surface 101.

[0142] Among them, Figure 11 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 12 is in Figure 11A partial cross-sectional schematic diagram after etching treatment based on the shown structure.

[0143] 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, it is necessary to etch the first doped semiconductor layer 105 located on the first surface 101. During the etching process, the first protective layer 103 can be used as an etching barrier layer to avoid damage to the first pyramid 131a and the second pyramid 141a during the etching process, 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.

[0144] 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 2000 s to 5000 s.

[0145] 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.

[0146] In some examples, the treatment duration of the high-temperature treatment or high-temperature doping treatment can be 2100 s, 2200 s, 2300 s, 2400 s, 2500 s, 2600 s, 2700 s, 2800 s, 2900 s, 3000 s, 3100 s, 3200 s, 3300 s, 3400 s, 3500 s, 3600 s, 3700 s, 3800 s, 3900 s, 4000 s, 4100 s, 4200 s, 4300 s, 4400 s, 4500 s, 4600 s, 4700 s, 4800 s or 4900 s, etc.

[0147] In some cases, the high-temperature treatment can be an oxygen-free high-temperature process. By directly performing 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, thereby forming 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.

[0148] In other cases, the high-temperature treatment can be an oxygen-containing high-temperature process. While performing high-temperature treatment on the groove 151, 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.

[0149] In still other cases, the high-temperature doping treatment can be a source-passing high-temperature process. While performing high-temperature treatment on the groove 151, doping treatment and 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.

[0150] 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 is 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.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] In some cases, referring to Figure 7 , 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.

[0155] In some embodiments, referring to Figure 8 and Figure 13 , 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: referring to Figure 8 and Figure 13 , 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 13 , performing a doping treatment on the initial first surface 120 so that a part of the 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; referring to Figure 13 and Figure 3 or Figure 5The step of performing the first texturing process on the initial second region 150, that is, in step S3, using the second protective layer 107 as an etching barrier layer, retaining the second doped semiconductor layer 106 in the initial first region 140, and making the initial first region 140 a third textured surface including a plurality of third pyramids 111a, where the base size of the third pyramid 111a is smaller than the base size of the second pyramid 141a.

[0156] Among them, Figure 13 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.

[0157] 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 with 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.

[0158] Moreover, with reference to Figure 13 and Figure 9 , 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 on the initial second region 150 will be transformed into a damaged layer 104; with reference to Figure 13 and Figure 3 or Figure 5 , the second protective layer 107 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. Thus, with reference to Figure 7 , the remaining second doped semiconductor layer 106 is only located on the first region 111 to serve as a selective emitter structure 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.

[0159] In an 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.

[0160] It should be noted that the size relationship among the first pyramid 131a, the second pyramid 141a, and the third pyramid 111a is the same as that in the foregoing embodiment, and will not be elaborated herein.

[0161] In some cases, with reference to Figure 11And Figure 12 , 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 on the second surface 102 is retained, the manufacturing method may further include: with reference to Figure 13 And Figure 3 Or Figure 5 , adopting an acid pickling process to remove the remaining second protective layer 107 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.

[0162] In some cases, with reference to Figure 7 , 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.

[0163] In some examples, an atomic layer deposition process and / or a plasma enhanced chemical vapor deposition process may be adopted to form the first passivation layer 118 and the second passivation layer 128. It should be noted that the second passivation layer 128 on the first surface 101 and the first passivation layer 118 on the second surface 102 may be formed synchronously.

[0164] 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 description of the step of forming the first electrode 109 above.

[0165] In some cases, the metal paste may include at least one of silver, lead, copper, tin, gold, lead or nickel.

[0166] It should be noted that in the manufacturing method provided in 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. 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 remains unchanged first, then gradually increases, and finally gradually decreases to zero, it is beneficial to make the thickness of the damage layer 104 formed in step S2 different in different regions or the degree of internal damage different. On this basis, in step S3, the time consumed for the first texturing treatment to remove the damage layer 104 with different thicknesses also varies. Then, the first texturing treatment will expose different parts of the initial substrate 110 covered by the damage layer 104 at different times, and further perform texturing treatment on the remaining initial substrate 110 at different times. Therefore, it is beneficial to form the groove 151 jointly surrounded by the bottom surface 131 and the slope 141, and form different textured surfaces on the bottom surface 131 and the slope 141, as well as the slope 141 with a lower steepness.

[0167] Another embodiment of the present disclosure further provides a photovoltaic module, which is used to convert the received light energy into electrical energy. The following will describe in detail the photovoltaic module provided in another embodiment of the present disclosure 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 described in detail herein.

[0168] With reference to Figures 1 to 6 , and Figure 14 and Figure 15 , 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 the photovoltaic cells provided in the foregoing embodiments; an encapsulation adhesive 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 adhesive film 41 facing away from the battery string. The photovoltaic cells 40 are electrically connected in the form of a whole piece or 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 14 is a partial three-dimensional structural schematic diagram of the photovoltaic module provided in another embodiment of the present disclosure; Figure 15 is Figure 14 a cross-sectional structural 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 may 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 may 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 may 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 15 , multiple cell strings may be electrically connected through the conductive strip 402. Figure 15 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 towards the same side, so that the conductive strips are respectively connected to different sides of two adjacent cell wafers. In some embodiments, the cell wafers may also have the electrodes with different polarities facing the same side, that is, the electrodes of multiple adjacent cell wafers are sequentially arranged in the order of the first polarity, the second polarity, and the first polarity. Then the conductive strip connects 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 co-extruded film can be prepared by extruding one or more raw materials onto another film that has already been made during the film processing, or by bonding different types of films that have already 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 can 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 can be a concave-convex surface or a velvet 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 can 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 examples for implementing the present disclosure. In actual applications, various changes can be made 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, and a slope connecting the bottom surface and the first area, the slope is inclined toward the first area, and the bottom surface and the slope form a groove; The bottom surface is a first velvet surface including a plurality of first pyramids, and the slope is a second velvet surface including a plurality of second pyramids, wherein the tower height of the first pyramid is greater than the tower height of the second pyramid.

2. The photovoltaic cell according to claim 1, characterized in that: Some of the second pyramids have pits at their apexes.

3. The photovoltaic cell according to claim 2, characterized in that: The ratio of the volume of the pit to the volume of the second pyramid having the pit is 0.01 to 0.

2.

4. The photovoltaic cell according to claim 1, characterized in that: In the same groove, along the first direction, the length of the bottom surface is a first length, the length of the slope is a second length, and the ratio of the second length to the first length is 0.001 to 0.

01.

5. The photovoltaic cell according to claim 1, characterized in that: The slope is inclined toward the first area at an angle of 40° to 55°.

6. The photovoltaic cell according to claim 1, characterized in that: The first zone is a third velvet surface including multiple third pyramids, the base size of the third pyramid is smaller than the base size of the second pyramid and the base size of the first pyramid; and / or the tower height of the second pyramid is smaller than the tower height of the first pyramid and the tower height of the third pyramid; and / or the reflectivity of the second velvet surface is smaller than the reflectivity of the first velvet surface and the reflectivity of the third velvet surface.

7. The photovoltaic cell according to claim 1, characterized in that: Also includes: A first protective layer covers the bottom surface and the slope.

8. The photovoltaic cell according to claim 7, 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.

9. 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 substrate is a substrate, the initial first area is transformed into a first area of ​​the substrate, the initial second area is transformed into a second area of ​​the substrate, the substrate located in the second area includes a bottom surface recessed into the substrate, and a slope connecting the bottom surface and the first area, the slope is inclined toward the first area, and the bottom surface and the slope surround the groove; The bottom surface is a first velvet surface including a plurality of first pyramids, the slope is a second velvet surface including a plurality of second pyramids, and the height of the first pyramids is greater than the height of the second pyramids.

10. The method for manufacturing a photovoltaic cell according to claim 9, 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 0.016 J / mm 2 ~0.19J / mm 2 In the third stage, the radiation intensity of the laser spot decreases by 0.01 J / mm per 1 μm distance. 2 ~0.04J / 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 .

11. The method for manufacturing a photovoltaic cell according to claim 9, 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℃.

12. The method for manufacturing a photovoltaic cell according to claim 9, 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 and the slope; 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.

13. The method for manufacturing a photovoltaic cell according to claim 12, 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.

14. The method for manufacturing a photovoltaic cell according to claim 9, 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.

15. 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 8, or by connecting a plurality of photovoltaic cells formed by the method for manufacturing a photovoltaic cell according to any one of claims 9 to 14; 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 away from the battery string.

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