Solar cell and photovoltaic module

Abstract

The embodiment of the present application relates to the photovoltaic field, and provides a solar cell and a photovoltaic module, the solar cell comprises: a substrate, the substrate has a first surface and a second surface arranged oppositely, the first surface is provided with first regions and second regions arranged alternately, the second regions are formed with grooves relative to the first regions; a passivation contact structure located in the first regions; wherein the side surface of the groove or the side surface of the passivation contact structure has a recess concave along a first direction, the recess comprises a first side surface and a second side surface, the first side surface is connected with the first regions, and the included angle between the first side surface and the second side surface is a first obtuse angle; the first direction refers to the direction of the second regions to the first regions; a passivation layer, the passivation layer covers the surface of the passivation contact structure and the inner wall surface of the groove; a first electrode, the first electrode is located in the passivation layer, and the first electrode is electrically connected with the passivation contact structure. The solar cell provided by the embodiment of the present application can at least improve the photoelectric conversion efficiency of the solar cell.

Description

Technical Field

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

[0002] Currently, with the gradual depletion of fossil fuels, solar cells are becoming increasingly widely used as a new energy alternative. A solar cell is a device that converts sunlight into electrical energy. Solar cells utilize the photovoltaic principle to generate charge carriers, which are then extracted using electrodes, thus facilitating the efficient utilization of electrical energy.

[0003] Current solar cells mainly include IBC cells (Interdigitated Back Contact), TOPCON (Tunnel Oxide Passivated Contact) cells, PERC cells (Passivated emitter and real cell), and heterojunction cells. Different film layer configurations and functional limitations are used to reduce optical losses and decrease photogenerated carrier recombination on and within the silicon substrate, thereby improving the photoelectric conversion efficiency of solar cells.

[0004] However, the photoelectric conversion efficiency of current solar cells is still unsatisfactory. Summary of the Invention

[0005] This application provides a solar cell and a photovoltaic module, which at least helps to improve the photoelectric conversion efficiency of the solar cell.

[0006] According to some embodiments of this application, one aspect of this application provides a solar cell, comprising: a substrate having a first surface and a second surface disposed opposite to each other, the first surface having alternating first and second regions, a first distance between the first region and the second surface being greater than a second distance between the second region and the second surface, and the second region having a groove formed relative to the first region; a passivation contact structure located at least in the first region; wherein the side of the groove or the side of the passivation contact structure has a recessed depression along a first direction, the recess including a continuous first side and a second side, the first side being connected to the first region, and the included angle between the first side and the second side being a first obtuse angle; the first direction refers to the direction from the second region to the first region; a passivation layer covering the surface of the passivation contact structure and the inner wall of the groove; and a first electrode located on the passivation layer and electrically connected to the passivation contact structure.

[0007] In some embodiments, the side of the groove has the recess, and the ratio of the length of the second side to the length of the first side is in the range of 8 to 30.

[0008] In some embodiments, the depth of the recess along the first direction is less than or equal to 200 nm.

[0009] In some embodiments, the passivated contact structure includes a tunneling dielectric layer and a doped semiconductor layer, the tunneling dielectric layer being located on the first region, the doped semiconductor layer being located on the tunneling dielectric layer, and the side of the doped semiconductor layer having the recess; the ratio of the length of the second side to the length of the first side is in the range of 8 to 30.

[0010] In some embodiments, the doped semiconductor layer is doped with an N-type dopant element, and the depth of the recess along the first direction is less than or equal to 800 nm.

[0011] In some embodiments, the doped semiconductor layer is doped with a P-type dopant element, the doped semiconductor layer includes a continuous first portion and a second portion, the first portion being located on the tunneling dielectric layer, the second portion extending along the end of the first portion to the groove, and the side of the second portion having the recess.

[0012] In some embodiments, the depth of the recess along the first direction is less than or equal to 200 nm.

[0013] In some embodiments, the length of the second portion along the first direction is less than or equal to 1 μm.

[0014] In some embodiments, the inner wall surface of the groove has a micro-textured structure, which includes a pyramid structure, a pyramid-like structure, a prism structure, or a prism-like structure.

[0015] In some embodiments, the passivation layer covers the first side and the second side, and the passivation layer has a third side and a fourth side, the third side corresponding to the first side and the fourth side corresponding to the second side, and the included angle between the third side and the fourth side is a second obtuse angle, the second obtuse angle being less than or equal to the first obtuse angle.

[0016] In some embodiments, the first obtuse angle ranges from 100° to 140°.

[0017] In some embodiments, the inner wall surface of the groove and the side surface of the groove form a third obtuse angle, the third obtuse angle being in the range of 110° to 150°.

[0018] In some embodiments, the device further includes a second electrode located on the second surface.

[0019] In some embodiments, the device further includes: a second passivated contact structure located in the second region, the passivation layer covering the second passivated contact structure; and a second electrode located in the second region and electrically connected to the second passivated contact structure.

[0020] According to some embodiments of this application, another aspect of this application provides a photovoltaic module, including: a battery string consisting of a plurality of solar cells as described in any one of the above embodiments; an encapsulating film for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulating film opposite to the battery string.

[0021] The technical solution provided in this application has at least the following advantages:

[0022] The solar cell provided in this application has the following characteristics: First, the first distance between the first region and the second surface is greater than the second distance between the second region and the second surface. The second region has a groove formed relative to the first region, thus the surface of the substrate is a non-flat surface. The uneven structure formed by the convexity of the first region and the concavity of the second region can increase the internal reflection of incident light. Second, the passivation contact structure is located in the first region but not in the second region. The first region has a first electrode, thereby forming a local passivation structure. The high doping of the passivation contact structure can reduce the contact resistance. The absence of a passivation contact structure in the second region can avoid the adverse effects caused by high doping and the optical loss caused by the passivation contact structure itself. Third, the side of the groove or the side of the passivation contact structure has a recessed depression along the first direction. This depression is similar to an inverted pyramid structure. This depression can serve as a light-trapping structure, which can improve the internal reflectivity of the solar cell and thus increase the photoelectric conversion efficiency. Attached Figure Description

[0023] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the drawings in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this application or in the conventional art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A cross-sectional view of a solar cell provided in an embodiment of this application;

[0025] Figure 2 A scanning electron microscope image of the boundary between the first and second regions in a solar cell provided in an embodiment of this application;

[0026] Figure 3 for Figure 2 A magnified view of a portion of the second region;

[0027] Figure 4 This is another scanning electron microscope image of the boundary between the first and second regions in a solar cell provided in an embodiment of this application;

[0028] Figure 5 for Figure 4 A magnified view of a portion of the central depression;

[0029] Figure 6 Another scanning electron microscope image of the boundary between the first and second regions in a solar cell provided in an embodiment of this application;

[0030] Figure 7 for Figure 6 A magnified view of a portion of point B in the middle;

[0031] Figure 8 for Figure 6 A magnified view of a portion of the central depression;

[0032] Figure 9 Another scanning electron microscope image of the boundary between the first and second regions in a solar cell provided in an embodiment of this application;

[0033] Figure 10 for Figure 9 A magnified view of a section at the border between the two sides;

[0034] Figure 11 for Figure 10 A magnified view of a portion of the central depression;

[0035] Figure 12 A cross-sectional view of another solar cell provided in an embodiment of this application;

[0036] Figure 13 A cross-sectional view of a solar cell provided in another embodiment of this application;

[0037] Figure 14 A cross-sectional view of a photovoltaic module provided in yet another embodiment of this application;

[0038] Figure 15 Another cross-sectional view of a photovoltaic module provided in yet another embodiment of this application. Detailed Implementation

[0039] As can be seen from the background technology, the photoelectric conversion efficiency of current solar cells is not good.

[0040] This application provides a solar cell that forms a first light-trapping structure by setting the first region and the second region to be non-flush; secondly, a depression is formed on the side of the groove and the side of the passivated contact structure to form a second light-trapping structure, thereby further increasing the internal reflectivity of the incident light.

[0041] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0042] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0043] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0044] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0045] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0046] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0047] In the accompanying drawings corresponding to the embodiments of this application, the thickness and area of ​​the layers are enlarged for better understanding and ease of description. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component may be "directly" located on the surface of the other component, or there may be a third component between the two components. Conversely, when describing a component on the surface of another component, or when another component is formed or disposed on the surface of a component, it indicates that there is no third component between the two components. Furthermore, when describing a component as being "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0048] In the description of the embodiments of this application, when a component "includes" another component, other components are not excluded unless otherwise stated, and other components may be further included. Furthermore, when a component such as a layer, film, region, or plate is referred to as being "on / located" on another component, it can be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or it can have another component present in between. Moreover, 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 indicates that no other components are located in between.

[0049] The terminology used in the description of the various embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims, the term "part" is also intended to include the plural form unless the context clearly indicates otherwise. Components include layers, films, regions, or plates, etc.

[0050] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0051] Figure 1 A cross-sectional view of a solar cell provided in an embodiment of this application; Figure 2 A scanning electron microscope image of the boundary between the first and second regions in a solar cell provided in an embodiment of this application; Figure 3 for Figure 2 A magnified view of a portion of the second region; Figure 4 This is another scanning electron microscope image of the boundary between the first and second regions in a solar cell provided in an embodiment of this application; Figure 5 for Figure 4 A magnified view of a portion of the central depression; Figure 6 Another scanning electron microscope image of the boundary between the first and second regions in a solar cell provided in an embodiment of this application; Figure 7 for Figure 6 A magnified view of a portion of point B in the middle; Figure 8 for Figure 6 A magnified view of a portion of the central depression; Figure 9 Another scanning electron microscope image of the boundary between the first and second regions in a solar cell provided in an embodiment of this application; Figure 10 for Figure 9 A magnified view of a section at the border between the two sides; Figure 11 for Figure 10 A magnified view of a portion of the concave area.

[0052] It should be noted that, Figures 2-4 , Figures 6-7 as well as Figure 9 This is a scanning electron microscope (SEM) image of a solar cell, with dashed lines indicating the boundaries between the various film layers. A scanning electron microscope (SEM) image is formed by scanning a shaped solar cell with a scanning electron microscope (SEM), generating physical signals, and then converting these physical signals into image information using a detector. Figure 1 And the following Figure 12 and Figure 13 The solar cells shown are illustrated with the top side as the front and the bottom side as the back.

[0053] According to some embodiments of this application, one aspect of this application provides a solar cell for improving the photoelectric conversion efficiency of a solar cell. (Referring to the references...) Figure 1 and Figure 5 , Figure 1 and Figure 8 or Figure 1 and Figure 10The solar cell includes: a substrate 100 having a first surface 101 and a second surface 102 disposed opposite to each other; alternating first regions 11 and second regions 12 disposed on the first surface 101; a first distance between the first region 11 and the second surface 102 being greater than a second distance between the second region 12 and the second surface 102; and a groove 103 formed in the second region 12 relative to the first region 11; a passivation contact structure 110 located at least in the first region 11; wherein the side of the groove 103 or the side of the passivation contact structure 110 has a groove along the first region 11. A recess 120 is recessed in the first direction X. The recess 120 includes a continuous first side surface 121 and a second side surface 122. The first side surface 121 is connected to the first region 11. The included angle between the first side surface 121 and the second side surface 122 is a first obtuse angle α. The first direction X refers to the direction from the second region 12 to the first region 11. A passivation layer 131 covers the surface of the passivation contact structure 110 and the inner wall surface of the groove 103. A first electrode 132 is located on the passivation layer 131 and is electrically connected to the passivation contact structure 110.

[0054] The solar cell provided in this application embodiment has the following characteristics: First, the first distance between the first region 11 and the second surface 102 is greater than the second distance between the second region 12 and the second surface 102. The second region 12 has a groove 103 formed relative to the first region 11. Thus, the surface of the substrate 100 is a non-flat surface. The uneven structure formed by the convexity of the first region 11 and the concavity of the second region 12 can increase the internal reflection of incident light. Second, the passivation contact structure 110 is located in the first region 11 but not in the second region 12. The first electrode 132 is provided on the first region 11, thereby forming a local passivation structure. The passivation contact structure 110 is provided, and the high doping of the passivation contact structure 110 can reduce the contact resistance. The second region 12 does not have the passivation contact structure 110, which can avoid the adverse effects caused by high doping and the optical loss caused by the passivation contact structure 110 itself. Third, the side of the groove 103 or the side of the passivation contact structure 110 has a recess 120 that is concave in the first direction X. This recess 120 is similar to an inverted pyramid structure. This recess 120 can serve as a light trapping structure, which can improve the internal reflectivity of the solar cell and thus increase the photoelectric conversion efficiency.

[0055] In some embodiments, the material of the substrate 100 may be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon or germanium. The elemental semiconductor material may be monocrystalline, polycrystalline, amorphous, or microcrystalline (a state simultaneously possessing both monocrystalline and amorphous states is called microcrystalline). For example, silicon may be at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon.

[0056] In some embodiments, the substrate 100 may also be a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, silicon germanide, silicon carbide, gallium arsenide, indium gallium dihydrogen phosphate, perovskite, cadmium telluride, copper indium selenide, etc. The substrate 100 may also be a sapphire substrate 100, a silicon-on-insulator substrate 100, or a germanium-on-insulator substrate 100.

[0057] In some embodiments, the substrate 100 can be an N-type semiconductor substrate 100 or a P-type semiconductor substrate 100. The N-type semiconductor substrate 100 is doped with an N-type dopant element, which can be any one of group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type semiconductor substrate 100 is doped with a P-type dopant element, which can be any one of group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0058] In some embodiments, with Figure 1 Taking the solar cell shown as an example, the first side 101 is the back side, and the second side 102 is the front side. Here, "front" and "back" are relative terms; "front" refers to the side facing the sunlight vertically, and "back" refers to the side facing away from the sunlight vertically. In other embodiments, for example... Figure 12 The first side, 101, is the front; the second side, 102, is the back. Further details will be provided later. Figure 12 A detailed explanation will be provided.

[0059] In some embodiments, the solar cell is a single-sided cell, with the front side serving as the light-receiving surface to receive incident light and the back side serving as the backlighting surface. The backlighting surface can also receive incident light, but its efficiency in receiving incident light is somewhat lower than that of the light-receiving surface.

[0060] In some embodiments, the solar cell is a bifacial cell, meaning that both the front and back sides of the substrate 100 can serve as light-receiving surfaces and can be used to receive incident light.

[0061] In some embodiments, the first region 11 refers to the region where the first electrode 132 is projected onto the reference plane, and the first region 11 serves as a functional region for forming a first type of metal electrode; the second region 12 refers to the region of the substrate 100 other than the first region 11, that is, the region other than the projected image of the first electrode 132 onto the reference plane.

[0062] It should be noted that, to ensure that all films contacted by the first electrode 132 are corresponding functional films, the range of the first region 11 is set to be greater than or equal to the orthographic projection range of the first electrode 132 on the reference plane. That is, any orthographic projection of the first electrode 132 on the reference plane is located within the first region 11, and the distance between the edge of the first region 11 and the edge of the orthographic projection pattern is greater than or equal to 0. The reference plane is a flat surface perpendicular to the thickness direction Z of the substrate 100. The reference plane is parallel to the plane containing the first direction X and perpendicular to the thickness direction Z of the substrate 100.

[0063] In addition, the first region 11 and the second region 12 are regions defined by functionally dividing the substrate 100 (or the first surface 101) to illustrate the distribution of the various film layer structures of the solar cell. Both actually belong to the substrate 100 (or the first surface 101), and there is no boundary between different regions. Only the film layers on them may be different. For example, the first region 11 has a first passivation contact structure and a first electrode 132, and the second region 12 has a passivation layer 131.

[0064] In some embodiments, reference Figure 1 The difference between the first distance and the second distance is less than or equal to 5 μm, meaning the depth h of the groove 103 is less than or equal to 5 μm. Thus, the first surface 101 of the substrate 100 is a rough surface with an uneven structure. The constraint of the groove 103 can increase the refractive index of the incident light, thereby improving the photoelectric conversion efficiency of the back-contact solar cell. Furthermore, the depth h of the groove 103 ranges from 0.5 μm to 1.5 μm. Within this range, the depth of the etching substrate 100 can be controlled. While ensuring that the first passivated contact structure 110 on the second region 12 is completely etched, less etching of the substrate 100 is required, avoiding the adverse effects caused by excessive etching of the substrate 100. Secondly, it can also reduce the etching time and the amount of etching solution, lowering the fabrication cost.

[0065] Specifically, the depth h of the groove 103 can be 0.5μm, 0.8μm, 1.2μm, 1.5μm, 2.3μm, 2.6μm, 3.1μm, 3.8μm, 4.2μm, 4.5μm or 4.9μm.

[0066] In some embodiments, the inner wall surface of the groove 103 and the side surface of the groove 103 form a third obtuse angle β, the third obtuse angle β being in the range of 110° to 150°. Thus, an obtuse angle is formed between the bottom surface of the groove 103 and the side surface of the groove 103, and the side surface of the groove 103 is inclined relative to the bottom surface, thereby increasing the internal reflectivity of the incident light.

[0067] The third obtuse angle β between the bottom surface and the side surface of the groove 103 can be 110°, 115°, 120°, 125°, 130°, 135°, 140°, 145°, or 150°. For example... Figure 2 The included angle β shown is 130.2°.

[0068] In some embodiments, reference Figure 2 The inner wall of the groove 103 has a micro-textured structure 105, which includes a pyramid structure, a pyramid-like structure, a prism structure, or a prism-like structure. The size of the micro-textured structure 105 is below 2 μm. Size refers to the length and height of the base of the cross-section. The micro-textured structure can improve the internal reflectivity of incident light, reduce optical loss, and thus improve photoelectric conversion efficiency.

[0069] refer to Figure 3 The film structure subsequently formed on the microtextured structure, such as the passivation layer 131 covering the microtextured structure, does not completely fill the gaps between the microtextured structures, and its outermost surface still exhibits a microtextured structure.

[0070] In some embodiments, the passivation contact structure 110 includes a tunneling dielectric layer 111 and a doped semiconductor layer 112. The tunneling dielectric layer 111 is located on the first region 11, the doped semiconductor layer 112 is located on the surface of the tunneling dielectric layer 111, the passivation layer 131 is located on the surface of the doped semiconductor layer 112, and the first electrode 132 is electrically connected to the doped semiconductor layer 112.

[0071] The doped semiconductor layer 112 can form a band bend on the surface of the substrate 100, and the tunneling dielectric layer 111 causes an asymmetric shift in the energy band on the surface of the substrate 100, making the potential barrier for the majority carriers (also known as majority carriers) lower than the potential barrier for the minority carriers (also known as minority carriers). Therefore, the majority carriers can more easily tunnel through the tunneling dielectric layer 111, while the minority carriers have difficulty passing through the tunneling dielectric layer 111, so as to achieve selective transport of carriers.

[0072] Furthermore, the tunneling dielectric layer 111 provides chemical passivation. Specifically, due to interface state defects at the interface between the substrate 100 and the tunneling dielectric layer 111, the interface state density of the first surface 101 is relatively high. This increased interface state density promotes the recombination of photogenerated carriers, increasing the fill factor, short-circuit current, and open-circuit voltage of the back-contact solar cell, thereby improving the photoelectric conversion efficiency of the back-contact solar cell. By positioning the tunneling dielectric layer 111 on the first surface 101, the tunneling dielectric layer 111 provides chemical passivation to the surface of the substrate 100. Specifically, by saturating the dangling bonds of the substrate 100, it reduces the defect state density of the substrate 100, thereby reducing the recombination centers and lowering the carrier recombination rate.

[0073] The doped semiconductor layer 112 provides a field passivation effect. Specifically, an electrostatic field pointing towards the interior of the substrate 100 is formed on the surface of the substrate 100, causing minority carriers to escape from the interface, thereby reducing the minority carrier concentration and decreasing the carrier recombination rate at the interface of the substrate 100. This increases the open-circuit voltage, short-circuit current, and fill factor of the back-contact solar cell, thereby improving the photoelectric conversion efficiency of the back-contact solar cell.

[0074] In some embodiments, the thickness of the tunneling dielectric layer 111 is 0.5 nm to 10 nm. The thickness range of the tunneling dielectric layer 111 is 0.5 nm to 1.3 nm, 1.3 nm to 4.6 nm, 4.6 nm to 6.1 nm, or 6.1 nm to 10 nm. When the thickness of the tunneling dielectric layer 111 is within any of these ranges, it is relatively thin, allowing majority carriers to easily tunnel through the tunneling dielectric layer 111, while minority carriers have difficulty passing through, thus achieving selective carrier transport.

[0075] In some embodiments, the material of the tunneling dielectric layer 111 includes at least one of silicon oxide, amorphous silicon, microcrystalline silicon, nanocrystalline silicon, or silicon carbide.

[0076] In some embodiments, the doped semiconductor layer 112 includes at least one of a doped amorphous silicon layer, a doped polycrystalline silicon layer, a doped microcrystalline silicon layer, a doped silicon carbide layer, or a doped crystalline silicon layer.

[0077] A recess 120 is formed on the side of the groove 103 or the side of the passivated contact structure 110. The recess 120 is close to the structure of an inverted pyramid. This recess 120 can serve as a light trapping structure, which can improve the internal reflectivity of the solar cell and thus increase the photoelectric conversion efficiency.

[0078] In some embodiments, reference Figure 4 , Figure 6 or Figure 9The first obtuse angle α ranges from 100° to 140°. When the angle of the first obtuse angle α is within the above range, the depth of the light-trapping structure formed is relatively small, and it will not cause excessive etching to the substrate 100. The first obtuse angle α can be 100°, 105°, 110°, 115°, 120°, 125°, 130°, 135° or 140°.

[0079] Depression 120 can be located as follows Figure 4 The side surface of the substrate 100 shown, as Figure 6 The doped semiconductor layer 112 shown is located on the side or as shown in the diagram. Figure 9 The image shows the side of the p-type doped semiconductor layer 112. The following description, in conjunction with the accompanying drawings, will explain three different structures.

[0080] The first type: such as Figure 4 As shown, the recess 120 is located on the side of the base 100. (Reference) Figure 5 The first side 121 is connected to the first region 11, and the second side 122 is connected to the second region 12. The first length of the first side 121 is less than the second length of the second side 122. Thus, the recess 120 is positioned close to the passivation contact structure, and based on the inclined surface of the side of the groove 103, the thickness of the passivation layer 131 deposited in the recess 120 is relatively thick, and the thickness of the passivation layer 131 deposited in the passivation contact structure 110 is also moderate. The passivation layer 131 can form a good passivation effect on the area of ​​the recess 120, and can also passivate the side of the passivation contact structure 110.

[0081] In some embodiments, the ratio of the length of the second side 122 to the length of the first side 121 ranges from 8 to 30. The ratio of the length of the second side 122 to the length of the first side 121 can be 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28 or 30.

[0082] In some embodiments, the first length L1 of the first side 121 ranges from 50 nm to 400 nm. The first length L1 of the first side 121 can be 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm or 400 nm.

[0083] In some embodiments, the second length L2 of the second side surface 122 ranges from 0.5 μm to 3 μm. The second length L2 of the second side surface 122 can be 0.5 μm, 0.8 μm, 1.2 μm, 1.5 μm, 1.8 μm, 2.1 μm, 2.3 μm, 2.5 μm, 2.8 μm or 3 μm.

[0084] In some embodiments, the depth of the recess 120 along the first direction is less than or equal to 200 nm. That is, the first depth D1 of the recess 120 along the first direction is less than or equal to 200 nm. The depth of the recess 120 is moderate, so as not to form excessive etching on the substrate 100. The depth of the recess 120 along the first direction can be 50 nm, 70 nm, 90 nm, 110 nm, 130 nm, 150 nm, 180 nm or 200 nm.

[0085] It should be noted that, Figure 5 The first depth shown is not exactly the same as the first direction (reference). Figure 1 Parallel, but in practice, the first depth of the recess 120 along the first direction is parallel to... Figure 5 The first depth D1 shown is approximately the same.

[0086] The second type: such as Figure 6 As shown, the recess 120 is located on the side of the N-type doped semiconductor layer 112. (Reference) Figure 8 The first side surface 121 is connected to the first region 11, and the second side surface 122 is connected to the side surface of the groove 103. The first length of the first side surface 121 is less than the second length of the second side surface 122.

[0087] In some embodiments, the doped semiconductor layer 112 is doped with an N-type dopant element, and the depth of the recess 120 along the first direction is less than or equal to 800 nm. (Reference) Figure 8 The second depth D2 of the recess 120 along the first direction is less than or equal to 800 nm. The second depth D2 of the recess 120 along the first direction can be 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm or 800 nm.

[0088] In some embodiments, the ratio of the length of the second side 122 to the length of the first side 121 ranges from 8 to 30. The ratio of the length of the second side 122 to the length of the first side 121 can be 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28 or 30.

[0089] The third type: such as Figure 9 As shown, the recess 120 is located on the side of the p-type doped semiconductor layer 112. (Reference) Figure 10 The first side 121 is connected to the first region 11 through the side of the tunneling dielectric layer 111, and the second side 122 is connected to the top surface of the doped semiconductor layer 112. The first length of the first side 121 is less than the second length of the second side 122.

[0090] In some embodiments, the ratio of the length of the second side 122 to the length of the first side 121 ranges from 8 to 30. The ratio of the length of the second side 122 to the length of the first side 121 can be 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28 or 30.

[0091] In some embodiments, the first length L1 of the first side surface 121 ranges from 1 nm to 100 nm. The first length L1 of the first side surface 121 can be 1 nm, 10 nm, 30 nm, 35 nm, 60 nm, 70 nm, 85 nm or 100 nm.

[0092] In some embodiments, reference Figure 11 The second length L2 of the second side 122 ranges from 10nm to 200nm. The second length L2 of the second side 122 can be 10nm, 40nm, 80nm, 120nm, 160nm, 170nm, 185nm or 200nm.

[0093] In some embodiments, the depth of the recess 120 along the first direction is less than or equal to 200 nm. That is, the third depth D3 of the recess 120 along the first direction is less than or equal to 200 nm. The depth of the recess 120 is moderate, so as not to form excessive etching on the substrate 100. The depth of the recess 120 along the first direction can be 50 nm, 70 nm, 90 nm, 110 nm, 130 nm, 150 nm, 180 nm or 200 nm.

[0094] It should be noted that, Figure 11 The first depth shown is not exactly the same as the first direction (reference). Figure 1 Parallel, but in practice, the third depth of the depression 120 along the first direction is parallel to... Figure 11 The third depth D3 shown is approximately the same.

[0095] In some embodiments, reference Figure 4 or Figure 9 The doped semiconductor layer 112 is doped with a p-type dopant element. The doped semiconductor layer 112 includes a continuous first portion (not shown) and a second portion (not shown). The first portion is located on the tunneling dielectric layer 111, and the second portion extends along the end of the first portion to the groove 103. The side of the second portion has a recess 120. Thus, the doped semiconductor layer 112 protrudes from the substrate 100 and is located above the groove 103. Based on the structure of the doped semiconductor layer 112, a third light-trapping structure is formed between the doped semiconductor layer 112 and the substrate 100 to increase internal reflection.

[0096] In some embodiments, the length of the second portion along the first direction is less than or equal to 1 μm. The length of the second portion can be 0.01 μm, 0.05 μm, 0.11 μm, 0.3 μm, 0.6 μm, 0.8 μm, or 1 μm.

[0097] In some embodiments, reference Figure 4 The passivation layer 131 covers the first side 121 and the second side 122. The passivation layer 131 has a third side (not marked) and a fourth side (not marked). The third side corresponds to the first side 121, and the fourth side corresponds to the second side 122. The included angle between the third side and the fourth side is a second obtuse angle θ, which is less than or equal to the first obtuse angle. Thus, the passivation layer 131 deposited in the recess 120 is relatively thick, thereby forming a good passivation effect on the substrate 100.

[0098] refer to Figure 3 The surface of the passivation layer has aggregates 106, which can increase the internal reflectivity.

[0099] In some embodiments, the second surface 102 has a textured structure (not shown), which includes multiple pyramidal structures. The solar cell also includes an emitter layer 104 covering the textured structure. The emitter layer 104 is doped with a dopant element of a different conductivity type than the substrate 100; for example, if the substrate 100 is doped with an N-type dopant element, then the emitter layer is doped with a P-type dopant element. The solar cell also includes a second passivation layer 133 covering the emitter layer.

[0100] In some embodiments, the second passivation layer 133 may be a single-layer structure or a stacked structure, and the material of the second passivation layer 133 may be one or more of the following materials: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0101] In some embodiments, the material of the second passivation layer 133 is the same as that of the passivation layer 131, and the second passivation layer 133 and the passivation layer 131 are prepared in the same manufacturing process.

[0102] Continue to refer to Figure 1 In some embodiments, the solar cell further includes a second electrode 134, which is located on the second surface 102 and is electrically connected to the emitter layer 104.

[0103] In some embodiments, either the first electrode 132 or the second electrode 134 may be sintered from a burn-through metal paste or from a LECO (Laser-enhanced contact optimization) paste. The metal paste and the LECO paste may include at least one of silver, aluminum, copper, tin, gold, lead, or nickel.

[0104] It should be noted that, Figure 1 The first electrode 132 shown penetrates the passivation layer 131 and is in electrical contact with the doped semiconductor layer 112, and the second electrode 134 penetrates the second passivation layer 133 and is in electrical contact with the emitter layer 104, is only an example. In actual back-contact solar cells, the connection between the first electrode 132 and the doped semiconductor layer 112 can be a contact connection or an indirect connection through conductive particles; the connection between the second electrode 134 and the emitter layer 104 can be a contact connection or an indirect connection through conductive particles. The conductive particles can be silver crystals, silver aggregates, silver particles, or other conductive metal particles.

[0105] Figure 12 This is a cross-sectional view of another solar cell provided in an embodiment of this application.

[0106] refer to Figure 12 The first surface 101 of the substrate 100 is the front side, and the second surface 102 of the substrate 100 is the back side. The doped elements of the doped semiconductor layer 112 in the passivation contact structure 110 are of different conductivity types than the doped elements of the substrate 100. The first surface 101 of the substrate 100 has a textured structure (not marked), which includes multiple pyramid structures.

[0107] The back side of the substrate 100 has a second passivation layer 133, which covers the second surface 102 of the substrate 100, and the second electrode 134 is in contact with the surface of the substrate 100.

[0108] The solar cell provided in this application embodiment has the following characteristics: First, the first distance between the first region 11 and the second surface 102 is greater than the second distance between the second region 12 and the second surface 102. The second region 12 has a groove 103 formed relative to the first region 11. Thus, the surface of the substrate 100 is a non-flat surface. The uneven structure formed by the convexity of the first region 11 and the concavity of the second region 12 can increase the internal reflection of incident light. Second, the passivation contact structure 110 is located in the first region 11 but not in the second region 12. The first electrode 132 is provided on the first region 11, thereby forming a local passivation structure. The passivation contact structure 110 is provided, and the high doping of the passivation contact structure 110 can reduce the contact resistance. The second region 12 does not have the passivation contact structure 110, which can avoid the adverse effects caused by high doping and the optical loss caused by the passivation contact structure 110 itself. Third, the side of the groove 103 or the side of the passivation contact structure 110 has a recess 120 that is concave in the first direction X. This recess 120 is similar to an inverted pyramid structure. This recess 120 can serve as a light trapping structure, which can improve the internal reflectivity of the solar cell and thus increase the photoelectric conversion efficiency.

[0109] Accordingly, another embodiment of this application also provides a solar cell, which is a back-contact solar cell. The aforementioned grooves and recesses can also be formed at the boundary between the P-region and the N-region. The differences from the above embodiment will be described in detail, while the similarities can be found in the previous embodiment. Figure 1 The solar cell shown.

[0110] Figure 13 This is a cross-sectional view of a solar cell provided in another embodiment of this application.

[0111] refer to Figure 13 The back-contact solar cell includes: a substrate 200 having a first surface 201 and a second surface 202 disposed opposite to each other; alternating first regions 21 and second regions 22 are disposed on the first surface 201; a first distance between the first region 21 and the second surface 202 is greater than a second distance between the second region 22 and the second surface 202; and a groove 203 formed in the second region 22 relative to the first region 21; and a passivation contact structure 210, which is at least located in the first region 21; wherein the side of the groove 203 or the passivation contact structure... The side of 210 has a recessed area along the first direction X. The recess includes a continuous first side and a second side. The first side is connected to the first region 21. The included angle between the first side and the second side is a first obtuse angle. The first direction X refers to the direction from the second region 22 to the first region 21. A passivation layer 231 covers the surface of the passivation contact structure 210 and the inner wall of the groove 203. A first electrode 232 is located on the passivation layer 231 and is electrically connected to the passivation contact structure 210.

[0112] In some embodiments, the first region 21 refers to the region where the first electrode 232 is projected onto the reference plane, and the first region 21 serves as a functional region for forming a first type of metal electrode; similarly, the second region 22 refers to the region where the second electrode 234 is projected onto the reference plane, and the second region 22 serves as a functional region for forming a second type of metal electrode.

[0113] In some embodiments, a gap region (also a non-metallic electrode region) is provided between the first region 21 and the second region 22. The gap region refers to the area where the orthographic projections of the first electrode 232 and the second electrode 234 on the reference plane do not overlap, i.e., the gap region serves as a functional area where no metallic electrode is formed. In other embodiments, there is no gap region between the first region 21 and the second region 22, and there is a height difference between the first region 21 and the second region 22, so that the film layer on the first region 21 and the film layer on the second region 22 do not contact each other.

[0114] In addition, the first region 21, the second region 22 and the interval region are areas defined by functional partitioning of the substrate 200 (or the first surface 201) to illustrate the distribution of the film structure of the back contact solar cell. All three actually belong to the substrate 200 (or the first surface 201), and there is no boundary between the different regions. Only the film layers on them may be different.

[0115] In some embodiments, the device further includes: a second passivation contact structure 240 located in the second region 22, and a passivation layer 231 covering the second passivation contact structure 240; and a second electrode 234 located on the second region 22 and electrically connected to the second passivation contact structure 240.

[0116] In some embodiments, the second passivation contact structure 240 includes a second tunneling dielectric layer 241 and a second doped semiconductor layer 242. The second tunneling dielectric layer 241 is located on the second region, the second doped semiconductor layer 242 is located on the surface of the second tunneling dielectric layer 241, the passivation layer 231 is located on the surface of the second doped semiconductor layer 242, and the second electrode 234 is electrically connected to the second doped semiconductor layer 242.

[0117] The function, material, and thickness of the second tunneling dielectric layer 241 can be referred to the description of the tunneling dielectric layer 111 above; the function and material of the second doped semiconductor layer 242 can be referred to the description of the doped semiconductor layer 112 above.

[0118] The difference between the doped semiconductor layer 212 and the second doped semiconductor layer 242 is that the doped semiconductor layer 212 is either an N-type doped layer or a P-type doped layer; and the second doped semiconductor layer 242 is either an N-type doped layer or a P-type doped layer.

[0119] Continue to refer to Figure 13 The second surface of the substrate has a surface field 205 and a second passivation layer 233, the second passivation layer 233 covering the surface field 205.

[0120] It should be noted that, Figure 13 The grooves shown and the side surfaces of the passivated contact structures also have the recesses in the above embodiments. The structures are different depending on the doping type of the doped semiconductor layer. For details, please refer to the description of the recesses in the previous embodiment, which will not be described here. Figure 13 The related contents of the substrate 200, passivation contact structure 210, tunneling dielectric layer 211, doped semiconductor layer 212, groove 203, and first electrode 232 shown are the same as those of the substrate 100, passivation contact structure 110, tunneling dielectric layer 111, doped semiconductor layer 112, groove 103, and first electrode 132 in the previous embodiment.

[0121] According to some embodiments of this application, another aspect of this application provides a tandem battery, which includes: a bottom battery, which is a solar cell as described in any of the above embodiments; and a top battery, which is located on one side of the back side of the substrate of the bottom battery.

[0122] In some embodiments, the stacked battery has a first grid line of a first polarity and a second grid line of a second polarity. The bottom battery is... Figure 1 In the solar cell shown, the first grid line refers to the second electrode of the solar cell, and the second grid line refers to the electrode of the top cell. The bottom cell is... Figure 12 In the solar cell shown, the first grid line refers to the first electrode of the solar cell, and the second grid line refers to the electrode of the top cell. The bottom cell is... Figure 13 In the back-contact solar cell shown, the first grid line refers to the first electrode of the back-contact solar cell, and the second grid line refers to the second electrode of the back-contact solar cell.

[0123] In some embodiments, an interface layer is provided between the top battery and the bottom battery, and the interface layer also covers the passivated contact structure on the back side.

[0124] It is worth noting that the stacked solar cells in the embodiments of this application can be two-layer solar cells, three-layer solar cells, or stacked solar cells with more than three layers.

[0125] In some embodiments, the top cell can be a perovskite solar cell, which includes: a first transport layer, a perovskite substrate, a second transport layer, a transparent conductive layer, and an antireflection layer stacked together. The first transport layer is directly opposite the bottom cell.

[0126] In some embodiments, the first transport layer may be either an electron transport layer or a hole transport layer, and the second transport layer may be either an electron transport layer or a hole transport layer.

[0127] According to some embodiments of this application, another aspect of this application provides a photovoltaic module. (See reference...) Figure 14 or Figure 15 The photovoltaic module includes: a battery string consisting of a plurality of solar cells 30 as described in any of the above embodiments; an encapsulating film 31 for covering the surface of the battery string; and a cover plate 32 for covering the surface of the encapsulating film 31 facing away from the battery string. Figure 14 A cross-sectional view of a photovoltaic module provided in yet another embodiment of this application; Figure 15 Another cross-sectional view of a photovoltaic module provided in yet another embodiment of this application.

[0128] A connecting component 318 is used to electrically connect two adjacent solar cells 30. Specifically, in some embodiments, multiple solar cells 30 can be electrically connected through the connecting component 318, which is welded to the main grid / sub-grid on the solar cell 30.

[0129] In some embodiments, the connecting member 318 is welded to a sub-grid on the battery cell, the sub-grid including a first electrode and a second electrode. In some embodiments, the connecting member 318 is welded to a main grid on the battery cell, the main grid including a first main grid and a second main grid, the first main grid being welded to a first electrode and the second main grid being welded to a second electrode.

[0130] In some embodiments, the encapsulating film 31 includes a first encapsulating film and a second encapsulating film. The first encapsulating film covers one of the front or back sides of the back-contact solar cell, and the second encapsulating film covers the other of the front or back sides of the back-contact solar cell. Specifically, at least one of the first encapsulating film or the second encapsulating film may be an organic encapsulating film such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate copolymer (EVA) film, polyvinyl octene coelastomer (POE) film, or polyethylene terephthalate (PET) film.

[0131] It is worth noting that the first encapsulating film and the second encapsulating film still have a dividing line before the lamination process. After the lamination process, the photovoltaic module will no longer have the concept of the first encapsulating film and the second encapsulating film. That is, the first encapsulating film and the second encapsulating film have formed an integral encapsulating film 31.

[0132] In some embodiments, the cover plate 32 can be a glass cover plate, a plastic cover plate, or other cover plate with light-transmitting function. Specifically, the surface of the cover plate 32 facing the encapsulating film 31 can be an uneven surface, thereby increasing the utilization rate of incident light. The cover plate 32 includes a first cover plate and a second cover plate, the first cover plate being opposite to the first encapsulating film, and the second cover plate being opposite to the second encapsulating film; or the first cover plate being opposite to the side of the solar cell that is in back contact with the solar cell, and the second cover plate being opposite to the other side of the solar cell that is in back contact with the solar cell.

[0133] While this application discloses preferred embodiments as described above, it is not intended to limit the scope of the claims. Any person skilled in the art can make various possible variations and modifications without departing from the concept of this application. Therefore, the scope of protection of this application should be determined by the scope defined in the claims. Furthermore, the embodiments and accompanying drawings in this specification are merely illustrative and do not represent the full scope of protection of the claims.

[0134] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of this application. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A solar cell, characterized in that, include: The substrate has a first surface and a second surface disposed opposite to each other. The first surface is provided with alternating first and second regions. The first distance between the first region and the second surface is greater than the second distance between the second region and the second surface. The second region has a groove formed relative to the first region. A passivated contact structure, wherein the passivated contact structure is at least located in the first region; Wherein, the side of the groove or the side of the passivation contact structure has a recess that is concave inward along a first direction, the recess includes a continuous first side and a second side, the first side is connected to the first area, and the included angle between the first side and the second side is a first obtuse angle; the first direction refers to the direction from the second area to the first area; A passivation layer covering the surface of the passivation contact structure and the inner wall of the groove; A first electrode is located on the passivation layer and is electrically connected to the passivation contact structure.

2. The solar cell according to claim 1, characterized in that, The groove has a recess on its side, the length of the second side is a first length, the length of the second side is a second length, and the ratio of the first length to the second length is in the range of 8 to 30.

3. The solar cell according to claim 2, characterized in that, The depth of the depression along the first direction is less than or equal to 200 nm.

4. The solar cell according to claim 1, characterized in that, The passivated contact structure includes a tunneling dielectric layer and a doped semiconductor layer. The tunneling dielectric layer is located on the first region, and the doped semiconductor layer is located on the tunneling dielectric layer. The side of the doped semiconductor layer has the recess. The length of the second side is a first length, and the length of the first side is a second length. The ratio of the first length to the second length is in the range of 8 to 30.

5. The solar cell according to claim 4, characterized in that, The doped semiconductor layer is doped with N-type dopant elements, and the depth of the recess along the first direction is less than or equal to 800 nm.

6. The solar cell according to claim 4, characterized in that, The doped semiconductor layer is doped with a P-type dopant element. The doped semiconductor layer includes a continuous first portion and a second portion. The first portion is located on the tunneling dielectric layer, and the second portion extends along the end of the first portion to the groove. The side of the second portion has the recess.

7. The solar cell according to claim 6, characterized in that, The depth of the depression along the first direction is less than or equal to 200 nm.

8. The solar cell according to claim 6, characterized in that, The length of the second part along the first direction is less than or equal to 1 μm.

9. The solar cell according to claim 1, characterized in that, The inner wall of the groove has a micro-textured structure, which includes a pyramid structure or a prism structure.

10. The solar cell according to claim 1, characterized in that, The passivation layer covers the first side and the second side, and the passivation layer has a third side and a fourth side. The third side corresponds to the first side, and the fourth side corresponds to the second side. The angle between the third side and the fourth side is a second obtuse angle, which is less than or equal to the first obtuse angle.

11. The solar cell according to claim 1, characterized in that, The first obtuse angle ranges from 100° to 140°.

12. The solar cell according to claim 1, characterized in that, The inner wall of the groove forms a third obtuse angle with the side of the groove, and the third obtuse angle is in the range of 110° to 150°.

13. The solar cell according to any one of claims 1 to 12, characterized in that, Also includes: The second electrode is located on the second surface.

14. The solar cell according to any one of claims 1 to 12, characterized in that, Also includes: A second passivated contact structure is located in the second region, and the passivation layer covers the second passivated contact structure. The second electrode is located on the second region and is electrically connected to the second passivated contact structure.

15. A photovoltaic module, characterized in that, include: A battery string comprising a plurality of solar cells as described in any one of claims 1 to 14; An encapsulating film is used to cover the surface of the battery string; A cover plate is used to cover the surface of the encapsulating film that faces away from the battery string.

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