Solar cells and solar cell modules

Abstract

In the field of photovoltaic power generation, a solar cell and a solar cell module capable of improving photoelectric conversion efficiency are provided. [Solution] The solar cell has a first surface and a second surface arranged back to back, and the first surface has first and second regions arranged alternately, and the second region includes a substrate having a groove formed in it relative to the first region, a passivation contact structure located in the first region, a passivation layer covering the surface of the passivation contact structure and the inner wall surface of the groove, and a first electrode located on the passivation layer and electrically connected to the passivation contact structure, and the side of the groove or the side of the passivation contact structure has a recess that is recessed inward along a first direction that is the direction from the second region to the first region, and the recess includes a continuous first side surface and a second side surface, the first side surface is connected to the first region, and the angle between the first side surface and the second side surface is a first obtuse angle.

Description

[Technical Field]

[0001] TECHNICAL FIELD Embodiments of the present application relate to the field of photovoltaics, and in particular to solar cells and solar modules. [Background technology]

[0002] As fossil fuels are gradually being depleted, solar cells are becoming more and more widely used as a new alternative energy source. Solar cells are devices that convert solar light energy into electrical energy. Solar cells utilize the photovoltaic principle to generate carriers, which are then extracted using electrodes, making them advantageous for the effective use 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 Rear Cell), and heterojunction solar cells. Different film layer configurations and functional limitations can reduce optical loss and reduce the recombination of photogenerated carriers on the surface and inside the silicon substrate, thereby improving the photoelectric conversion efficiency of solar cells.

[0004] However, the photoelectric conversion efficiency of current solar cells remains low. Summary of the Invention

[0005] Embodiments of the present application provide solar cells and solar cell modules that are at least advantageous in improving the photoelectric conversion efficiency of solar cells.

[0006] According to some embodiments of the present application, one aspect of the embodiments of the present application provides a solar cell having a first surface and a second surface arranged back to back, the first surface having first and second regions arranged alternately, 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, the second region including a substrate having a groove formed therein with respect to the first region, a passivation contact structure located at least in the first region, a passivation layer covering a surface of the passivation contact structure and an inner wall surface of the groove, and a first electrode located on the passivation layer and electrically connected to the passivation contact structure, wherein a side surface of the groove or a side surface of the passivation contact structure has a recess recessed inward along a first direction from the second region to the first region, the recess including a first side surface and a second side surface that are continuous, the first side surface being connected to the first region, and an angle between the first side surface and the second side surface being a first obtuse angle.

[0007] In another embodiment, the side surface of the groove has the recess, and the ratio of the length of the second side surface to the length of the first side surface is in the range of 8-30.

[0008] In another embodiment, the depth of the recess along the first direction is 200 nm or less.

[0009] In another embodiment, the passivation contact structure includes a tunnel dielectric layer located in the first region and a doped semiconductor layer located in the tunnel dielectric layer so as to have the recess on a side surface, and the ratio of the length of the second side surface to the length of the first side surface is in the range of 8 to 30.

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

[0011] In another embodiment, the doped semiconductor layer is doped with a P-type doping element, and the doped semiconductor layer includes a continuous first portion and a continuous second portion, the first portion being located in the tunnel dielectric layer, and the second portion extending along an edge of the first portion to the trench, and having a side surface with the recess.

[0012] In another embodiment, the depth of the recess along the first direction is 200 nm or less.

[0013] In another embodiment, the length of the second portion along the first direction is 1 μm or less.

[0014] In another embodiment, the inner wall surface of the groove has a fine texture structure, and the fine texture structure includes a pyramidal structure, a nearly pyramidal structure, a prism structure, or a nearly prism structure.

[0015] In another embodiment, the passivation layer covers the first side and the second side and has a third side and a fourth side, the third side corresponds to the first side, the fourth side corresponds to the second side, and an angle between the third side and the fourth side is a second obtuse angle that is less than or equal to the first obtuse angle.

[0016] In another embodiment, the first obtuse angle is in the range of 100° to 140°.

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

[0018] In another embodiment, the device further comprises a second electrode located on the second surface.

[0019] In another embodiment, the semiconductor device further includes a second passivation contact structure located in the second region and covered by the passivation layer, and a second electrode located in the second region and electrically connected to the second passivation contact structure.

[0020] According to another embodiment of the present application, another aspect of the embodiment of the present application provides a solar cell module including a battery string formed by connecting a plurality of solar cells described in any one of the above embodiments, a sealing adhesive film that covers the surface of the battery string, and a cover plate that covers the surface of the sealing adhesive film that faces away from the battery string.

[0021] The technical solutions according to the embodiments of the present application have at least the following advantages:

[0022] In the solar cell according to the embodiment of the present application, first, a first distance between the first region and the second surface is greater than a second distance between the second region and the second surface, and the second region has a groove formed therein relative to the first region, so that the surface of the substrate is uneven, and the uneven structure formed by the convex portions in the first region and the concave portions in the second region can improve internal reflection of incident light. Second, the passivation contact structure is located in the first region but not in the second region, and a first electrode is provided in the first region, forming a localized passivation structure. The placement of the passivation contact structure and the high doping of the passivation contact structure can reduce contact resistance. Since the second region does not have a passivation contact structure, the adverse effects of high doping and optical loss due to the passivation contact structure itself can be avoided. Third, the side of the groove or the side of the passivation contact structure has a recess that is recessed inward along the first direction, and this recess resembles an inverted pyramid structure and can function as a light trapping structure, thereby improving the internal reflectivity of the solar cell and thereby improving the photoelectric conversion efficiency. [Brief explanation of the drawings]

[0023] One or more embodiments are illustratively described by figures in the corresponding drawings, and these illustrative descriptions are not intended to limit the embodiments, and unless otherwise specified, the figures in the drawings are not intended to limit the scale. In order to more clearly explain the embodiments of the present application or the technical means in the prior art, the drawings necessary for the embodiments are briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can derive other drawings based on these drawings without any creative efforts.

[0024] [Figure 1] 1 is a cross-sectional view of a solar cell according to an embodiment of the present application. [Figure 2] 1 is a scanning electron microscope photograph of the vicinity of the boundary between the first region and the second region of a solar cell according to an example of the present application. [Figure 3] FIG. 3 is a partial enlarged view of a second region in FIG. 2. [Figure 4] 10 is another scanning electron microscope photograph of the vicinity of the boundary between the first region and the second region of the solar cell according to one example of the present application. [Figure 5] FIG. 5 is a partial enlarged view of a recess in FIG. 4. [Figure 6] 10 is another scanning electron microscope photograph of the vicinity of the boundary between the first region and the second region of the solar cell according to one example of the present application. [Figure 7] FIG. 7 is a partial enlarged view of a portion B in FIG. 6. [Figure 8] FIG. 7 is a partial enlarged view of a recess in FIG. 6. [Figure 9] 10 is yet another scanning electron microscope photograph of the vicinity of the boundary between the first and second regions of a solar cell according to an example of the present application. [Figure 10] FIG. 10 is a partially enlarged view of the vicinity of the boundary in FIG. [Figure 11] FIG. 11 is a partially enlarged view of a recess in FIG. [Figure 12] FIG. 2 is a cross-sectional view of another solar cell according to an embodiment of the present application. [Figure 13] FIG. 2 is a cross-sectional view of a solar cell according to another embodiment of the present application. [Figure 14]FIG. 10 is a cross-sectional view of a solar cell module according to yet another embodiment of the present application. [Figure 15] FIG. 10 is another cross-sectional view of a solar cell module according to yet another embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0025] As can be seen from the background art, the photoelectric conversion efficiency of current solar cells is still low.

[0026] In the solar cell according to the embodiment of the present application, the first region and the second region are not flush with each other to form a first light trapping structure, and recesses are formed on the side of the groove and the side of the passivation contact structure, i.e., a second light trapping structure is formed, which further improves the internal reflectance of incident light.

[0027] In the description of the embodiments of the present application, the technical terms "first," "second," etc. are merely used to distinguish between different objects and cannot be understood as indicating or implying relative importance, or as implying the number, specific order, or hierarchical relationship of the technical features shown. In the description of the embodiments of the present application, "plurality" means two or more, unless otherwise clearly and specifically limited.

[0028] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present application. Appearances of the phrase in various places in the present specification do not necessarily refer to the same embodiment, nor are they exclusive, independent, or alternative embodiments to other embodiments. Those skilled in the art will understand, both explicitly and implicitly, that the embodiments described herein can be combined with other embodiments.

[0029] In the description of the embodiments of the present application, the term "and / or" is a relational relationship that describes related objects and indicates that three relations may exist. For example, A and / or B can indicate three cases: A exists, A and B simultaneously exist, and B exists. In addition, the character " / " in this specification generally indicates that the related objects before and after it are in an "or" relationship.

[0030] In describing the examples of the present application, the term "plurality" refers to two or more (including two); similarly, "multiple sets" refers to two or more sets (including two sets); and "multiple sheets" refers to two or more sheets (including two sheets).

[0031] In describing the embodiments of the present application, the orientations or positional relationships indicated by technical terms such as "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" are based on the orientations or positional relationships shown in the drawings and are intended merely to facilitate and simplify the description of the embodiments of the present application. They do not indicate or suggest that the devices or parts shown must have a specific orientation and be configured and operated in a specific orientation, and therefore should not be understood as limiting the embodiments of the present application.

[0032] In the description of the embodiments of the present application, unless otherwise clearly specified or limited, the technical terms "attached," "coupled," "connected," "fixed," etc. should be understood in a broad sense, and may refer to, for example, a fixed connection, a detachable connection, or an integral connection, a mechanical connection, an electrical connection, a direct connection, an indirect connection via an intermediate medium, an internal communication between two parts, or an interactive relationship between two parts. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present application according to the specific circumstances.

[0033] In the drawings corresponding to the embodiments of the present application, the thickness and area of ​​layers are exaggerated for better understanding and ease of explanation. When a component (e.g., a layer, thin film, region, or substrate) is described as being on another component or on the surface of another component, the component may be located directly on the surface of the other component, or a third component may be present between these two components. Conversely, when a component is described as being on the surface of another component, or as being formed or provided on the surface of a component, it means that no third component is present between these two components. Furthermore, when a component is described as being "substantially" formed on the surface of another component, it means that the component is not formed on the entire surface (or front surface) of the other component, but is not formed on only a portion of the edge of the entire surface.

[0034] In the description of the embodiments of the present application, when a component "includes" another component, it does not exclude other components and may further include other components unless otherwise specified. Furthermore, when a component such as a layer, film, region, or plate is described as being "present / located on" another component, the component may be "directly" located on the other component (i.e., located on the surface of the other component, with no other components present between them), or another component may be present between them. Furthermore, 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 present between them.

[0035] 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 described and in the appended claims, "portions" is intended to include the plural unless the context clearly dictates otherwise. Elements include elements such as layers, films, regions, or plates.

[0036] Hereinafter, each embodiment of the present application will be described in detail with reference to the drawings. Those skilled in the art will understand that each embodiment of the present application provides many technical details to help readers better understand the present application. However, even without these technical details and various changes and modifications based on each of the following embodiments, the technical means claimed for protection of the present application can be realized.

[0037] FIG. 1 is a cross-sectional view of a solar cell according to one embodiment of the present application, FIG. 2 is a scanning electron microscope photograph of the vicinity of the boundary between the first region and the second region of a solar cell according to one embodiment of the present application, FIG. 3 is a partial enlarged view of the second region in FIG. 2, FIG. 4 is another scanning electron microscope photograph of the vicinity of the boundary between the first region and the second region of a solar cell according to one embodiment of the present application, FIG. 5 is a partial enlarged view of the recess in FIG. 4, FIG. 6 is yet another scanning electron microscope photograph of the vicinity of the boundary between the first region and the second region of a solar cell according to one embodiment of the present application, FIG. 7 is a partial enlarged view of portion B in FIG. 6, FIG. 8 is a partial enlarged view of the recess in FIG. 6, FIG. 9 is yet another scanning electron microscope photograph of the vicinity of the boundary between the first region and the second region of a solar cell according to one embodiment of the present application, FIG. 10 is a partial enlarged view of the vicinity of the boundary in FIG. 9, and FIG. 11 is a partial enlarged view of the recess in FIG. 10.

[0038] 2 to 4, 6 to 7, and 9 are scanning electron microscope photographs of solar cells, with the boundaries between each film layer indicated by dotted lines. Scanning electron microscope photographs are images formed by scanning a molded solar cell with a scanning electron microscope (abbreviated as SEM), generating physical signals, and converting the physical signals into image information using a detector. The solar cells shown in FIG. 1 and the subsequent FIGS. 12 and 13 are illustrated with the upward-facing side as the front and the downward-facing side as the back.

[0039] According to another embodiment of the present application, one aspect of the embodiment of the present application provides a solar cell that improves the photoelectric conversion efficiency of the solar cell. As shown in any combination of Figures 1 and 5, 1 and 8, or 1 and 10, the solar cell includes a substrate 100 having a first surface 101 and a second surface 102 arranged back to back, the first surface 101 having first regions 11 and second regions 12 arranged alternately, a first distance between the first region 11 and the second surface 12 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; and a surface of the passivation contact structure 110. and a passivation layer 131 covering the inner wall surface of the groove 103, and a first electrode 132 located on the passivation layer 131 and electrically connected to the passivation contact structure 110, wherein a side surface of the groove 103 or a side surface of the passivation contact structure 110 has a recess 120 recessed inward along a first direction X which is a direction from the second region 12 to the first region 11, the recess 120 including a continuous first side surface 121 and a second side surface 122, the first side surface 121 being connected to the first region 11, and the angle between the first side surface 121 and the second side surface 122 being a first obtuse angle α.

[0040] In the solar cell according to the embodiment of the present application, first, a first distance between the first region 11 and the second surface 102 is greater than a second distance between the second region 12 and the second surface 102, and a groove 103 is formed in the second region 12 relative to the first region 11. Thus, the surface of the substrate 100 is non-flat, and the uneven structure formed by the convex portions in the first region 11 and the concave portions in the second region 12 can improve internal reflection of incident light. Second, the passivation contact structure 110 is located in the first region 11, not in the second region 12, and the first electrode 132 is provided in the first region 11, thereby forming a localized passivation structure. The placement of the passivation contact structure 110 and its high doping can reduce contact resistance. The absence of the passivation contact structure 110 in the second region 12 can avoid the adverse effects of high doping and optical loss due to 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 recessed inward along the first direction X, which resembles an inverted pyramid structure and can function as a light trapping structure, thereby improving the internal reflectivity of the solar cell and thereby improving the photoelectric conversion efficiency.

[0041] In another embodiment, 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 in a single crystalline state, a polycrystalline state, an amorphous state, or a microcrystalline state (a state having both single crystalline and amorphous states is called a microcrystalline state). For example, silicon may be at least one of single crystalline silicon, polycrystalline silicon, amorphous silicon, and microcrystalline silicon.

[0042] In other embodiments, the material of the substrate 100 may be a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, silicon germanium, silicon carbide, gallium arsenide, indium gallium, perovskite, cadmium telluride, copper indium selenium, etc. The substrate 100 may be a sapphire substrate 100, a silicon-on-insulator substrate 100, or a germanium-on-insulator substrate 100.

[0043] In other embodiments, the substrate 100 may 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 doping element, which may 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 doping element, which may be any one of Group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0044] In another embodiment, taking the solar cell shown in FIG. 1 as an example, the first surface 101 is the back surface, and the second surface 102 is the front surface. The terms "front" and "rear" in the front and rear surfaces are relative, i.e., "front" refers to the side facing sunlight along the vertical direction, and "rear" refers to the side facing away from sunlight along the vertical direction. In another embodiment, for example, in FIG. 12, the first surface 101 is the front surface, and the second surface 102 is the rear surface, which will be described in detail below with reference to FIG. 12.

[0045] In another embodiment, the solar cell is a single-sided cell, with the front side being the light-receiving side and the back side being the rear side. The rear side can also receive incident light, but the efficiency of receiving incident light is lower than that of the light-receiving side.

[0046] In another embodiment, the solar cell is a bifacial cell, ie, both the front and back surfaces of the substrate 100 are light-receiving surfaces and can receive incident light.

[0047] In another embodiment, the first region 11 refers to the region where the orthogonal projection of the first electrode 132 onto the reference plane is located, and the first region 11 functions as a first type functional region where a metal electrode is formed, and the second region 12 refers to a region other than the first region 11 of the substrate 100, i.e., a region other than the orthogonal projection of the first electrode 132 onto the reference plane.

[0048] In order to ensure that all film layers in contact with the first electrode 132 are corresponding functional film layers, the range of the first region 11 is set to be equal to or greater than the range of the orthogonal projection of the first electrode 132 onto the reference plane, i.e., any orthogonal projection of the first electrode 132 onto 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 orthogonal projection is equal to or greater than 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 in which the first direction X lies and perpendicular to the thickness direction Z of the substrate 100.

[0049] Furthermore, the first region 11 and the second region 12 are regions set by functionally dividing the substrate 100 (or the first surface 101) in order to explain the distribution of each film layer structure of the solar cell; both actually belong to the substrate 100 (or the first surface 101), there is no boundary between the different regions, and the film layers located there 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.

[0050] In another embodiment, as shown in FIG. 1, the difference between the first distance and the second distance is 5 μm or less, i.e., the depth h of the groove 103 is 5 μm or less. In this manner, the first surface 101 of the substrate 100 is a roughened surface having a concave-convex structure. The groove 103 can improve the refractive index of incident light, thereby improving the photoelectric conversion efficiency of the back-contact solar cell. Furthermore, the depth h of the groove 103 is in the range of 0.5 μm to 1.5 μm. By setting the depth h of the groove 103 in this range, the etching depth of the substrate 100 can be controlled. While ensuring that the first passivation contact structure 110 on the second region is completely etched, the etching amount of the substrate 100 can be reduced, avoiding the adverse effects of over-etching the substrate 100. This reduces the etching time of the substrate 100 and the amount of etching solution used, thereby reducing manufacturing costs.

[0051] Specifically, the depth h of the groove 103 may be 0.5 μm, 0.8 μm, 1.2 μm, 1.5 μm, 2.3 μm, 2.6 μm, 3.1 μm, 3.8 μm, 4.2 μm, 4.5 μm, or 4.9 μm.

[0052] In another embodiment, the inner wall surface of the groove 103 and the side surface of the groove 103 form a third obtuse angle β, and the third obtuse angle β is in the range of 110° to 150°. In this way, the bottom surface of the groove 103 and the side surface of the groove 103 form an obtuse angle, and the side surface of the groove 103 is inclined with respect to the bottom surface, thereby improving the internal reflectance of incident light.

[0053] The third obtuse angle β between the bottom surface of groove 103 and the side surface of groove 103 may be 110°, 115°, 120°, 125°, 130°, 135°, 140°, 145°, or 150°. For example, the angle β shown in Figure 2 is 130.2°.

[0054] In another embodiment, as shown in FIG. 2, the inner wall surface of the groove 103 has a fine textured structure 105, which includes a pyramidal structure, a nearly pyramidal structure, a prism structure, or a nearly prism structure. The dimensions of the fine textured structure 105 are in the range of 2 μm or less. The dimensions refer to the length and height of the base of the cross section. The fine textured structure can improve the internal reflectance of incident light and reduce optical loss, thereby improving photoelectric conversion efficiency.

[0055] As shown in FIG. 3, a film layer structure, such as a passivation layer 131, subsequently formed on the fine-textured structure covers the fine-textured structure but does not completely fill the gaps between the fine-textured structures, and the outermost surface is still a fine-textured structure.

[0056] In another embodiment, the passivation contact structure 110 includes a tunnel dielectric layer 111 located in the first region 11 and a doped semiconductor layer 112 located on the surface of the tunnel dielectric layer 111, a passivation layer 131 located on the surface of the doped semiconductor layer 112, and a first electrode 132 electrically connected to the doped semiconductor layer 112.

[0057] The doped semiconductor layer 112 can form a band bending at the surface of the substrate 100, and the tunnel dielectric layer 111 generates an asymmetric offset in the bands at the surface of the substrate 100, so that the potential barrier for the majority carriers (also called majority carriers) among the carriers is lower than the potential barrier for the minority carriers (also called minority carriers) among the carriers. Therefore, the majority carriers can easily pass through the tunnel dielectric layer 111 to quantum tunnel, while the minority carriers have difficulty passing through the tunnel dielectric layer 111, thereby realizing selective carrier transmission.

[0058] The tunnel dielectric layer 111 also exhibits a chemical passivation effect. Specifically, the presence of interface state defects at the interface between the substrate 100 and the tunnel dielectric layer 111 results in a high interface state density at the first surface 101. The 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 providing the tunnel dielectric layer 111 on the first surface 101, the tunnel dielectric layer 111 exhibits a chemical passivation effect on the surface of the substrate 100. Specifically, the tunnel dielectric layer 111 saturates dangling bonds in the substrate 100, thereby reducing the defect state density of the substrate 100 and reducing the number of recombination centers in the substrate 100, thereby lowering the carrier recombination rate.

[0059] The doped semiconductor layer 112 exhibits an electric field passivation effect. Specifically, an electrostatic field is formed on the surface of the substrate 100, which is directed toward the inside of the substrate 100, causing minority carriers to escape from the interface, thereby reducing the concentration of minority carriers and reducing the recombination rate of carriers at the interface of the substrate 100. This improves the open circuit voltage, short circuit current, and fill factor of the back-contact solar cell, and improves the photoelectric conversion efficiency of the back-contact solar cell.

[0060] In other embodiments, the thickness of the tunnel dielectric layer 111 is 0.5 nm to 10 nm. The thickness of the tunnel dielectric layer 111 is in the range of 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 tunnel dielectric layer 111 is in any of the above ranges, the thickness of the tunnel dielectric layer 111 is thin, and majority carriers can easily pass through the tunnel dielectric layer 111 to quantum tunnel, while minority carriers have difficulty passing through the tunnel dielectric layer 111, thereby realizing selective carrier transmission.

[0061] In another embodiment, the material of the tunnel dielectric layer 111 includes at least one of silicon oxide, amorphous silicon, microcrystalline silicon, nanocrystalline silicon, or silicon carbide.

[0062] In other embodiments, the doped semiconductor layer 112 comprises 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.

[0063] A recess 120 is formed on the side of the groove 103 or the side of the passivation contact structure 110, and the recess 120 resembles an inverted pyramid structure and can function as a light trapping structure, thereby improving the internal reflectivity of the solar cell and thereby improving the photoelectric conversion efficiency.

[0064] In other embodiments, the first obtuse angle α is in the range of 100° to 140°, as shown in Figure 4, 6, or 9. When the first obtuse angle α is in the above range, the formed light trapping structure has a small depth and does not cause excessive etching of the substrate 100. The first obtuse angle α may be 100°, 105°, 110°, 115°, 120°, 125°, 130°, 135°, or 140°.

[0065] The recess 120 may be located on the side of the substrate 100 as shown in Fig. 4, on the side of the N-type doped semiconductor layer 112 as shown in Fig. 6, or on the side of the P-type doped semiconductor layer 112 as shown in Fig. 9. Three different structures will be described below with reference to the respective drawings.

[0066] In the first type, as shown in FIG. 4, the recess 120 is located on the side of the substrate 100. As shown in FIG. 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 smaller than the second length of the second side 122. In this way, the recess 120 is located close to the passivation contact structure. Due to the inclined side of the groove 103, the thickness of the passivation layer 131 deposited in the recess 120 is thick, and the thickness of the passivation layer 131 deposited on the passivation contact structure 110 is also appropriate. Therefore, the passivation layer 131 not only provides a high passivation effect in the recess 120 region, but also passivates the side of the passivation contact structure 110.

[0067] In other embodiments, the ratio of the length of the second side 122 to the length of the first side 121 is in the range of 8 to 30. The ratio of the length of the second side 122 to the length of the first side 121 may be 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, or 30.

[0068] In other embodiments, the first length L1 of the first side surface 121 is in the range of 50 nm to 400 nm, and may be 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, or 400 nm.

[0069] In other embodiments, the second length L2 of the second side surface 122 is in the range of 0.5 μm to 3 μm, and may 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.

[0070] In another embodiment, the depth of the recess 120 in the first direction is 200 nm or less. That is, the first depth D1 of the recess 120 in the first direction is 200 nm or less. The depth of the recess 120 is moderate so that excessive etching of the substrate 100 does not occur. The depth of the recess 120 in the first direction may be 50 nm, 70 nm, 90 nm, 110 nm, 130 nm, 150 nm, 180 nm, or 200 nm.

[0071] Note that although the first depth shown in FIG. 5 is not perfectly parallel to the first direction (see FIG. 1), in reality, the depth of the recess 120 along the first direction is approximately the same as the first depth D1 shown in FIG. 5.

[0072] 6, the recess 120 is located on the side of the N-type doped semiconductor layer 112. As shown in FIG. 8, the first side 121 is connected to the first region 11, and the second side 122 is connected to the side of the groove 103. The first length of the first side 121 is smaller than the second length of the second side 122.

[0073] In another embodiment, the doped semiconductor layer 112 is doped with an N-type dopant, and the depth of the recess 120 along the first direction is 800 nm or less. As shown in Figure 8, the second depth D2 of the recess 120 along the first direction is 800 nm or less. The second depth D2 of the recess 120 along the first direction may be 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, or 800 nm.

[0074] In other embodiments, the ratio of the length of the second side 122 to the length of the first side 121 is in the range of 8 to 30. The ratio of the length of the second side 122 to the length of the first side 121 may be 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, or 30.

[0075] Third, as shown in Fig. 9, the recess 120 is located on the side of the P-type doped semiconductor layer 112. As shown in Fig. 10, a first side 121 is connected to the first region 11 by the side of the tunnel dielectric layer 111, and a second side 122 is connected to the top surface of the doped semiconductor layer 112. A first length of the first side 121 is smaller than a second length of the second side 122.

[0076] In other embodiments, the ratio of the length of the second side 122 to the length of the first side 121 is in the range of 8 to 30. The ratio of the length of the second side 122 to the length of the first side 121 may be 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, or 30.

[0077] In other embodiments, the first length L1 of the first side surface 121 is in the range of 1 nm to 100 nm, and may be 1 nm, 10 nm, 30 nm, 35 nm, 60 nm, 70 nm, 85 nm, or 100 nm.

[0078] 11, the second length L2 of the second side surface 122 is in the range of 10 nm to 200 nm, and may be 10 nm, 40 nm, 80 nm, 120 nm, 160 nm, 170 nm, 185 nm, or 200 nm.

[0079] In another embodiment, the depth of the recess 120 in the first direction is 200 nm or less. That is, the third depth D3 of the recess 120 in the first direction is 200 nm or less. The depth of the recess 120 in the first direction is moderate so that excessive etching of the substrate 100 does not occur. The depth of the recess 120 in the first direction may be 50 nm, 70 nm, 90 nm, 110 nm, 130 nm, 150 nm, 180 nm, or 200 nm.

[0080] Note that although the first depth shown in FIG. 11 is not perfectly parallel to the first direction (see FIG. 1), in reality, the third depth of the recess 120 along the first direction is approximately the same as the third depth D3 shown in FIG. 11.

[0081] 4 or 9, the doped semiconductor layer 112 is doped with a P-type doping element, and the doped semiconductor layer 112 includes a continuous first portion (not shown) and a continuous second portion (not shown), where the first portion is located in the tunnel dielectric layer 111, and the second portion extends along the edge of the first portion to the groove 103, with a side surface having a recess 120. In this way, the doped semiconductor layer 112 protrudes from the substrate 100 and is located above the groove 103, and the structure of the doped semiconductor layer 112 forms a third light trapping structure between the doped semiconductor layer 112 and the substrate 100 to improve internal reflection.

[0082] In other embodiments, the length of the second portion along the first direction is 1 μm or less. The length of the second portion along the first direction may be 0.01 μm, 0.05 μm, 0.11 μm, 0.3 μm, 0.6 μm, 0.8 μm, or 1 μm.

[0083] 4, the passivation layer 131 covers the first side surface 121 and the second side surface 122, and has a third side surface (not shown) and a fourth side surface (not shown), where the third side surface corresponds to the first side surface 121 and the fourth side surface corresponds to the second side surface 122, and the angle between the third side surface and the fourth side surface is a second obtuse angle θ that is less than or equal to the first obtuse angle. In this way, the passivation layer 131 deposited in the recess 120 is thick, and therefore, a high passivation effect can be achieved on the substrate 100.

[0084] As shown in FIG. 3, the surface of the passivation layer has agglomerates 106, which can improve the internal reflectivity.

[0085] In another embodiment, the second surface 102 has a textured structure (not shown), which includes a plurality of pyramid structures. The solar cell further includes a light-emitting layer 104 covering the textured structure, in which the light-emitting layer 104 is doped with a doping element having a conductivity type different from that of the substrate 100. For example, when the substrate 100 is doped with an N-type doping element, the light-emitting layer is doped with a P-type doping element. The solar cell further includes a second passivation layer 133 covering the light-emitting layer.

[0086] In other embodiments, the second passivation layer 133 may be a single-layer structure or a multi-layer structure, and the material of the second passivation layer 133 may be one or more of materials such as silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0087] In another embodiment, the second passivation layer 133 is made of the same material as the passivation layer 131 and is manufactured in the same manufacturing process as the passivation layer 131 .

[0088] As shown in FIG. 1, in another embodiment, the solar cell further includes a second electrode 134 located on the second surface 102 and electrically connected to the light-emitting layer 104 .

[0089] In other embodiments, any one of the first electrode 132 and the second electrode 134 may be formed by sintering a fire-through metal paste or a laser-enhanced contact optimization (LECO) paste, and the metal paste and the LECO paste may include at least one of silver, aluminum, copper, tin, gold, lead, or nickel.

[0090] 1, the first electrode 132 penetrates the passivation layer 131 and electrically contacts the doped semiconductor layer 112, and the second electrode 134 penetrates the second passivation layer 133 and electrically contacts the light-emitting layer 104. In an actual back-contact solar cell, the connection between the first electrode 132 and the doped semiconductor layer 112 may be direct contact or indirect contact via conductive particles. The connection between the second electrode 134 and the light-emitting layer 104 may be direct contact or indirect contact via conductive particles. The conductive particles may be silver crystals, silver aggregates, silver particles, or other conductive metal particles.

[0091] FIG. 12 is a cross-sectional view of another solar cell according to an embodiment of the present application.

[0092] As shown in FIG. 12, the first surface 101 of the substrate 100 is the front surface, the second surface 102 of the substrate 100 is the back surface, the doped elements of the doped semiconductor layer 112 of the passivation contact structure 110 and the doped elements of the substrate 100 have different conductivity types, and the first surface 101 of the substrate 100 has a textured structure (not shown), which includes a plurality of pyramid structures.

[0093] The backside of the substrate 100 has a second passivation layer 133 covering the second surface 102 of the substrate 100 , and a second electrode 134 contacts the front surface of the substrate 100 .

[0094] In the solar cell according to the embodiment of the present application, first, a first distance between the first region 11 and the second surface 102 is greater than a second distance between the second region 12 and the second surface 102, and a groove 103 is formed in the second region 12 relative to the first region 11. Thus, the surface of the substrate 100 is non-flat, and the uneven structure formed by the convex portions in the first region 11 and the concave portions in the second region 12 can improve internal reflection of incident light. Second, the passivation contact structure 110 is located in the first region 11, not in the second region 12, and the first electrode 132 is provided in the first region 11, thereby forming a localized passivation structure. The placement of the passivation contact structure 110 and its high doping can reduce contact resistance. The absence of the passivation contact structure 110 in the second region 12 can avoid the adverse effects of high doping and optical loss due to 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 recessed inward along the first direction X, which resembles an inverted pyramid structure and can function as a light trapping structure, thereby improving the internal reflectivity of the solar cell and thereby improving the photoelectric conversion efficiency.

[0095] Accordingly, another embodiment of the present application provides a solar cell that is a back-contact solar cell, in which the groove and recess may be formed near the boundary between the P region and the N region, and the differences from the above embodiment will be described in detail, and the same parts will be referred to the solar cell shown in FIG.

[0096] FIG. 13 is a cross-sectional view of a solar cell according to another embodiment of the present application.

[0097] As shown in FIG. 13 , the back-contact solar cell includes a substrate 200 having a first surface 201 and a second surface 202 arranged back to back, the first surface 201 having first regions 21 and second regions 22 arranged alternately, a first distance between the first region 21 and the second surface 202 being 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, a passivation contact structure 210 located at least in the first region 21, and a groove 203 formed in the second region 22 relative to the first region 21. The semiconductor device includes a passivation layer 231 covering the surface and the inner wall surface of the groove 203, and a first electrode 232 located on the passivation layer 231 and electrically connected to the passivation contact structure 210, wherein the side of the groove 203 or the side of the passivation contact structure 210 has a recess recessed inward along a first direction X, which is the direction from the second region 22 to the first region 21, and the recess includes a continuous first side and a second side, the first side is connected to the first region 21, and the angle between the first side and the second side is a first obtuse angle.

[0098] In another embodiment, the first region 21 refers to the region where the orthogonal projection of the first electrode 232 onto the reference plane is located, and the first region 21 functions as a first type functional region where a metal electrode is formed; similarly, the second region 22 refers to the region where the orthogonal projection of the second electrode 234 onto the reference plane is located, and the second region 22 functions as a second type functional region where a metal electrode is formed.

[0099] In another embodiment, a gap region (also called a non-metal electrode region) is provided between the first region 21 and the second region 22. The gap region refers to a region where the orthogonal projection of the first electrode 232 onto the reference plane and the orthogonal projection of the second electrode 234 onto the reference plane do not overlap, i.e., the gap region functions as a functional region where no metal electrode is formed. In another embodiment, there is no gap region between the first region 21 and the second region 22, and the first region 21 and the second region 22 have a step, and the film layer located in the first region 21 and the film layer located in the second region 22 do not contact each other.

[0100] Furthermore, the first region 21, the second region 22 and the spacing region are regions set by functionally dividing the substrate 200 (or the first surface 201) in order to explain the distribution of each film layer structure of a back-contact type solar cell, and all three actually belong to the substrate 200 (or the first surface 201), there are no boundaries between the different regions and the film layers located there may be different.

[0101] In another embodiment, the semiconductor device further includes a second passivation contact structure 240 located in the second region 22 and covered by the passivation layer 231, and a second electrode 234 located in the second region 22 and electrically connected to the second passivation contact structure 240.

[0102] In another embodiment, the second passivation contact structure 240 includes a second tunnel dielectric layer 241 located in the second region and a second doped semiconductor layer 242 located on the surface of the second tunnel 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.

[0103] For the function, material and thickness settings of the second tunnel dielectric layer 241, please refer to the description of the tunnel dielectric layer 111 above, and for the function and material settings of the second doped semiconductor layer 242, please refer to the description of the doped semiconductor layer 112 above.

[0104] Comparing the doped semiconductor layer 212 and the second doped semiconductor layer 242, the difference is that the doped semiconductor layer 212 is one of an N-type doped layer or a P-type doped layer, and the second doped semiconductor layer 242 is the other of an N-type doped layer or a P-type doped layer.

[0105] As shown in FIG. 13, the second surface of the substrate has a back surface field 205 and a second passivation layer 233 covering the back surface field 205 .

[0106] 13 also has recesses in the above-described embodiments, and the doping type of the doped semiconductor layer is different, so the structure is different. Specifically, the description of the recesses in the above-described embodiments can be referred to, and therefore the description will be omitted here. Regarding the contents related to the substrate 200, passivation contact structure 210, tunnel dielectric layer 211, doped semiconductor layer 212, groove 203, and first electrode 232 shown in FIG. 13, refer to the substrate 100, passivation contact structure 110, tunnel dielectric layer 111, doped semiconductor layer 112, groove 103, and first electrode 132 in the above-described embodiments.

[0107] According to another embodiment of the present application, another aspect of the embodiment of the present application provides a stacked battery including a bottom cell that is the solar cell described in any one of the above embodiments, and a top cell located on a back side of the substrate of the bottom cell.

[0108] In another embodiment, the stacked cells have first gridlines with a first polarity and second gridlines with a second polarity. If the bottom cell is the solar cell shown in Figure 1, the first gridlines are the second electrodes of the solar cell and the second gridlines are the electrodes of the top cell. If the bottom cell is the solar cell shown in Figure 12, the first gridlines are the first electrodes of the solar cell and the second gridlines are the electrodes of the top cell. If the bottom cell is the back-contact solar cell shown in Figure 13, the first gridlines are the first electrodes of the back-contact solar cell and the second gridlines are the second electrodes of the back-contact solar cell.

[0109] Another embodiment has an interface layer between the top and bottom cells, which covers the backside passivation contact structure.

[0110] The stacked solar cell in the embodiments of the present application may be a two-layer solar cell, a three-layer solar cell, or a three or more layer solar cell.

[0111] In another embodiment, the top cell may be a perovskite solar cell, comprising a first transport layer, a perovskite substrate, a second transport layer, a transparent conductive layer, and an anti-reflective layer, stacked together, with the first transport layer facing the bottom cell.

[0112] In other embodiments, the first transport layer may be one of an electron transport layer or a hole transport layer, and the second transport layer may be the other of an electron transport layer or a hole transport layer.

[0113] According to another embodiment of the present application, another aspect of the embodiment of the present application provides a solar cell module. As shown in Fig. 14 or 15, the solar cell module includes a cell string formed by connecting a plurality of solar cells 30 according to any one of the above embodiments, a sealing adhesive film 31 that covers the surface of the cell string, and a cover plate 32 that covers the surface of the sealing adhesive film 31 that faces away from the cell string. Fig. 14 is a cross-sectional view of a solar cell module according to yet another embodiment of the present application, and Fig. 15 is another cross-sectional view of a solar cell module according to yet another embodiment of the present application.

[0114] The solar cell module further includes a connection member 318 that electrically connects two adjacent solar cells 30. Specifically, in another embodiment, multiple solar cells 30 may be electrically connected by the connection member 318, and the connection member 318 is welded to the main grid / sub-grid of the solar cells 30.

[0115] In another embodiment, the connecting member 318 is welded to a sub-grid of the cell, the sub-grid including a first electrode and a second electrode, or in another embodiment, the connecting member 318 is welded to a main grid of the cell, the main grid including a first main grid and a second main grid, the first main grid welded to the first electrode and the second main grid welded to the second electrode.

[0116] In another embodiment, the sealing adhesive film 31 includes a first sealing adhesive film and a second sealing adhesive film, the first sealing adhesive film covering one of the front and back surfaces of the back-contact solar cell, and the second sealing adhesive film covering the other of the front and back surfaces of the back-contact solar cell. Specifically, at least one of the first sealing adhesive film and the second sealing adhesive film may be an organic sealing adhesive film such as a polyvinyl butyral (abbreviated as PVB) adhesive film, an ethylene-vinyl acetate copolymer (EVA) adhesive film, a polyethylene octene copolymer (POE) adhesive film, or a polyethylene terephthalate (PET) adhesive film.

[0117] Note that the first sealing adhesive film and the second sealing adhesive film have a boundary line before the lamination process, and after the solar cell module is formed after the lamination process, there is no concept of a first sealing adhesive film and a second sealing adhesive film; in other words, the first sealing adhesive film and the second sealing adhesive film form an integrated sealing adhesive film 31.

[0118] In another embodiment, the cover plate 32 may be a light-transmitting cover plate such as a glass cover plate or a plastic cover plate. Specifically, the surface of the cover plate 32 facing the sealing adhesive film 31 may be textured to improve the utilization efficiency of incident light. The cover plate 32 includes a first cover plate and a second cover plate, where the first cover plate faces the first sealing adhesive film and the second cover plate faces the second sealing adhesive film. Alternatively, the first cover plate faces one side of the back-contact solar cell and the second cover plate faces the other side of the back-contact solar cell.

[0119] Although the present application has been disclosed above by way of preferred embodiments, the scope of the claims is not limited thereto, and a person skilled in the art can make multiple possible changes and modifications without departing from the concept of the present application, so the scope of protection of the present application should be based on the scope defined by the claims of the present application. In addition, the examples and drawings in the specification of the present application are merely illustrative explanations and do not cover the entire scope of protection of the claims of the present application.

[0120] Those skilled in the art will understand that the above embodiments are specific examples for realizing the present application, and that various changes in form and details can be made in actual applications without departing from the spirit and scope of the present application. Since those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application, the scope of protection of the present application should be based on the content limited by the claims.

Claims

1. a substrate having a first surface and a second surface provided back to back, wherein first regions and second regions are provided on the first surface so as to be alternately arranged, a first distance between the first regions and the second surface is greater than a second distance between the second regions and the second surface, and a groove is formed in the second region relative to the first region; a passivation contact structure located at least in the first region; a passivation layer covering the surface of the passivation contact structure and the inner wall surface of the groove; a first electrode located in the passivation layer and electrically connected to the passivation contact structure; a side surface of the groove or a side surface of the passivation contact structure has a recess recessed inward along a first direction from the second region to the first region, the recess including a first side surface and a second side surface that are continuous, the first side surface being connected to the first region, and an angle between the first side surface and the second side surface being a first obtuse angle; A solar cell characterized by:

2. The side surface of the groove has the recess. The solar cell according to claim 1 .

3. The depth of the recess along the first direction is 200 nm or less. The solar cell according to claim 2 .

4. the passivation contact structure includes a tunnel dielectric layer located in the first region; and a doped semiconductor layer located in the tunnel dielectric layer so as to have the recess on a side surface thereof. The solar cell according to claim 1 .

5. The doped semiconductor layer is doped with an N-type doping element, The depth of the recess along the first direction is 800 nm or less. The solar cell according to claim 4 .

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

7. The depth of the recess along the first direction is 200 nm or less. The solar cell according to claim 6 .

8. The length of the second portion along the first direction is 1 μm or less. The solar cell according to claim 6 .

9. the inner wall surface of the groove has a fine texture structure; The micro-texture structure includes a pyramidal structure or a prism structure. The solar cell according to claim 1 .

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

11. The first obtuse angle is in the range of 100° to 140°. The solar cell according to claim 1 .

12. an inner wall surface of the groove and a side surface of the groove form a third obtuse angle; The third obtuse angle is in the range of 110° to 150°. The solar cell according to claim 1 .

13. further comprising a second electrode located on the second surface; The solar cell according to claim 1 .

14. a second passivation contact structure located in the second region and covered by the passivation layer; a second electrode located in the second region and electrically connected to the second passivation contact structure. The solar cell according to claim 1 .

15. a battery string formed by connecting a plurality of solar cells according to any one of claims 1 to 14; a sealing adhesive film that covers the surface of the battery string; a cover plate covering a surface of the sealing adhesive film that faces away from the battery string; A solar cell module characterized by:

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