Solar cell and photovoltaic module

Abstract

The utility model relates to photovoltaic field provides a solar cell and photovoltaic module, can improve the photoelectric conversion efficiency of solar cell at least. Solar cell includes: base, the surface of base includes at least first pyramid structure and second pyramid structure, and the first base side length of first pyramid structure is greater than the second base side length of second pyramid structure, and / or, the first height of first pyramid structure is greater than the second height of second pyramid structure, wherein, the side of first pyramid structure away from base includes the first cambered surface with first curvature radius, the side of second pyramid structure away from base includes the second cambered surface with second curvature radius, and the first curvature radius is greater than the second curvature radius, passivation layer, passivation layer is located base surface, and passivation layer covers first pyramid structure and second pyramid structure.

Description

Technical Field

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

[0002] The different crystal planes of a monocrystalline silicon wafer, such as the (110) and (111) planes, exhibit different corrosion rates in alkaline solutions, displaying anisotropy. As the reaction proceeds, numerous tetrahedral pyramids form on the silicon wafer surface. This process is often referred to as texturing, or "surface texturing." The pyramid-like tetrahedral pyramids formed on the surface of the monocrystalline silicon wafer effectively reduce its reflectivity. The lower the reflectivity of the monocrystalline silicon wafer, the more light it absorbs, and the higher the energy conversion efficiency of the solar cells assembled from it.

[0003] Texturing is the first step in the manufacturing process of crystalline silicon solar cells, and a well-textured surface structure plays a crucial role in subsequent processes. Typically, monocrystalline silicon solar cells use anisotropic alkaline etching to create a pyramidal structure, increasing the number of light reflections on the silicon wafer surface and significantly reducing surface reflectivity. However, the sharp apex and base of the pyramids can easily create numerous defects at these points during subsequent thin film deposition, leading to cell leakage and consequently affecting the solar cell's conversion efficiency. Utility Model Content

[0004] This utility model provides a solar cell and a photovoltaic module, which at least helps to improve the photoelectric conversion efficiency of the solar cell.

[0005] According to some embodiments of the present invention, one aspect of the present invention provides a solar cell, comprising: a substrate; the surface of the substrate includes at least a first type of pyramid structure and a second type of pyramid structure, wherein the first base length of the first type of pyramid structure is greater than the second base length of the second type of pyramid structure; and / or, the first height of the first type of pyramid structure is greater than the second height of the second type of pyramid structure; wherein the side of the first type of pyramid structure away from the substrate includes a first arc surface with a first radius of curvature, and the side of the second type of pyramid structure away from the substrate includes a second arc surface with a second radius of curvature, wherein the first radius of curvature is greater than the second radius of curvature; and a passivation layer located on the surface of the substrate, the passivation layer covering the first type of pyramid structure and the second type of pyramid structure.

[0006] In some embodiments, the first type of pyramid structure includes a first outer wall surface and a third arc surface, the first outer wall surface being connected to the first arc surface and the third arc surface, the third arc surface being connected to the base surface, and the third arc surface having a third radius of curvature; the second type of pyramid structure includes a second outer wall surface and a fourth arc surface, the second outer wall surface being connected to the second arc surface and the fourth arc surface, the fourth arc surface being connected to the base surface, and the fourth arc surface having a fourth radius of curvature; the third radius of curvature is less than or equal to the fourth radius of curvature.

[0007] In some embodiments, the first radius of curvature is greater than the third radius of curvature; the second radius of curvature is less than the fourth radius of curvature.

[0008] In some embodiments, the total area of ​​the orthographic projection of the first type of pyramid structure on the base is the first area, the total area of ​​the orthographic projection of the second type of pyramid structure on the base is the second area, and the ratio of the first area to the second area is 1.5 to 4.

[0009] In some embodiments, the ratio of the first base length to the first height is a first ratio, and the ratio of the second base length to the second height is a second ratio; the first ratio is greater than the second ratio.

[0010] In some embodiments, the length of the first base side is 1 μm to 2 μm, and the first height is 0.8 μm to 1.8 μm.

[0011] In some embodiments, the second bottom edge length is 0.1 μm to 0.2 μm, and the second height is 0.09 μm to 0.2 μm.

[0012] In some embodiments, the first radius of curvature is 30 nm to 100 nm.

[0013] In some embodiments, the second radius of curvature is 5 nm to 30 nm.

[0014] According to some embodiments of the present invention, another aspect of the present invention provides a photovoltaic module, comprising: a battery string, formed by connecting 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 facing away from the battery string.

[0015] The technical solution provided by this utility model embodiment has at least the following advantages:

[0016] In the technical solution provided by this utility model embodiment, different types of first-type pyramid structures and second-type pyramid structures are set, and both the first-type pyramid structures and the second-type pyramid structures are designed with rounded corners to form a first arc surface and a second arc surface, respectively. This can improve the density of the passivation layer, thereby improving the passivation performance. Secondly, the first radius of curvature is greater than the second radius of curvature. For large pyramid structures, a large first radius of curvature means that the first arc surface of the first-type pyramid structure has a small first curvature, resulting in a smaller degree of curvature, which can reduce the sharp corner effect caused by large pyramids. For small pyramids, their height is low, and their second radius of curvature is small, meaning that the second arc surface of the second-type pyramid structure has a large second curvature, resulting in a larger degree of curvature. The smaller height has less impact on the passivation layer, and the larger specific surface area resulting from the larger degree of curvature can improve the internal reflectivity and the subsequent contact performance with the electrode. Attached Figure Description

[0017] 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 the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of a solar cell provided in an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of a first pyramid structure in a solar cell according to an embodiment of the present invention;

[0020] Figure 3 This is a schematic diagram of a second pyramid structure in a solar cell according to an embodiment of the present invention;

[0021] Figure 4 A schematic diagram of an initial substrate provided in a method for fabricating a solar cell according to an embodiment of the present invention;

[0022] Figure 5 This is a schematic diagram illustrating the formation of a first initial pyramid structure and a second initial pyramid structure in a method for fabricating a solar cell according to an embodiment of the present invention.

[0023] Figure 6An electron microscope image of a method for fabricating a solar cell according to an embodiment of the present invention, showing the formation of a first initial pyramid structure and a second initial pyramid structure;

[0024] Figure 7 This is a schematic diagram of a structure for forming doped silicon glass in a method for preparing a solar cell according to an embodiment of the present invention.

[0025] Figure 8 An electron microscope image of a method for fabricating a solar cell according to an embodiment of the present invention, showing the formation of doped silicon glass.

[0026] Figure 9 This is a schematic diagram of a photovoltaic module according to another embodiment of the present invention. Detailed Implementation

[0027] As can be seen from the background technology, the photoelectric conversion efficiency of current solar cells is not good.

[0028] This utility model provides a solar cell and its photovoltaic module, which improves the passivation performance of the passivation layer deposited thereon by improving the morphology of the textured structure on the substrate surface, thereby improving the photoelectric conversion efficiency of the solar cell.

[0029] In the description of the embodiments of this utility model, 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 utility model, "multiple" means two or more, unless otherwise explicitly defined.

[0030] 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 the present invention. 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.

[0031] In the description of this utility model embodiment, the term "and / or" is merely a description of the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists, A and B exist simultaneously, and B exists. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0032] In the description of the embodiments of this utility model, 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).

[0033] In the description of the embodiments of this utility model, 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 utility model and simplifying the description, and do not 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 utility model.

[0034] In the description of the embodiments of this utility model, unless otherwise explicitly specified and limited, 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. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this utility model according to the specific circumstances.

[0035] In the accompanying drawings corresponding to the embodiments of this utility model, 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.

[0036] In the description of the embodiments of this utility model, 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.

[0037] 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.

[0038] The embodiments of this utility model 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 utility model to facilitate a better understanding of the invention. However, the technical solutions claimed by this utility model can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0039] According to some embodiments of the present invention, one embodiment of the present invention provides a solar cell that improves the passivation performance of the passivation layer deposited thereon by improving the morphology of the textured structure on the substrate surface, thereby improving the photoelectric conversion efficiency of the solar cell.

[0040] refer to Figures 1 to 3 The solar cell includes: a substrate 100; the surface of the substrate 100 includes at least a first type of pyramid structure 110 and a second type of pyramid structure 120, wherein the first base side length L1 of the first type of pyramid structure 110 is greater than the second base side length L2 of the second type of pyramid structure 120; and / or, the first height H1 of the first type of pyramid structure 110 is greater than the second height H2 of the second type of pyramid structure 120. The side of the first type of pyramid structure 110 away from the substrate includes a first arc surface 111 with a first radius of curvature R1, and the side of the second type of pyramid structure 120 away from the substrate includes a second arc surface 121 with a second radius of curvature R2, wherein the first radius of curvature R1 is greater than the second radius of curvature R2. The solar cell includes: a passivation layer 131, which is located on the surface of the substrate 100 and covers the first type of pyramid structure 110 and the second type of pyramid structure 120.

[0041] In the technical solution provided by this embodiment of the utility model, different types of first-type pyramid structures 110 and second-type pyramid structures 120 are provided, and both the first-type pyramid structure 110 and the second-type pyramid structure 120 are designed with rounded corners to form a first arc surface 111 and a second arc surface 121, respectively. This can improve the density of the passivation layer 131, thereby improving the passivation performance. Secondly, the first radius of curvature R1 is greater than the second radius of curvature R2. For large pyramid structures, a large first radius of curvature R1 means that the first curvature corresponding to the first arc surface 111 of the first-type pyramid structure 110 is small, and the degree of curvature is small, thereby reducing the sharp corner effect caused by the large pyramid. For small pyramids, their height is low, and the second radius of curvature R2 is small, meaning that the second curvature corresponding to the second arc surface 121 of the second-type pyramid structure 120 is large, and the degree of curvature is large. The small height has less impact on the passivation layer 131, and the larger specific surface area resulting from the larger degree of curvature can improve the internal reflectivity and the subsequent contact performance with the first electrode 141.

[0042] The above features and the effects achieved will be described in detail below with reference to the accompanying drawings.

[0043] 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.

[0044] 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, and copper indium selenide. The substrate 100 may also be a sapphire substrate, a silicon-on-insulator substrate, or a germanium-on-insulator substrate.

[0045] In some embodiments, substrate 100 may be an N-type semiconductor substrate. The N-type semiconductor substrate is doped with an N-type dopant element, which may be any one of group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). Substrate 100 may also be a P-type semiconductor substrate. The P-type semiconductor substrate is doped with a P-type dopant element, which may be any one of group III elements such as boron (B), indium (In), or gallium (Ga).

[0046] It should be noted that, Figure 1 , Figure 2 as well as Figure 3The reference numeral 4 in the attached figure refers to the surface 4 of the substrate, but the surface 4 of the substrate is virtual and does not represent the actual existence of a substrate surface.

[0047] The first type of pyramid structure 110 is a type of velvet structure, which can improve the internal reflectivity of incident light, thereby improving the photoelectric conversion efficiency. Multiple first-type pyramid structures 110 can be used, arranged adjacently or at intervals, or stacked or partially overlapped. This embodiment of the invention does not limit the number, arrangement, or shape of the first-type pyramid structures 110.

[0048] The apex of the first type of pyramid structure 110 is rounded to present the shape of the first arc surface 111. Compared with the sharp-angled apex, the first arc surface 111 has a higher flatness, which can avoid problems such as uneven distribution of the passivation layer at the apex and the bottom of the pyramid or uneven diffusion of doped elements in the doped layer caused by the sharp-angle effect.

[0049] The total area of ​​the projected surface area of ​​the first type of pyramid structure 110 onto the base is called the first area. The ratio between the first area and the surface area of ​​the base, i.e., the proportion of the first type of pyramid structure 110, is 60% to 80%. Within this range, a larger number of first type of pyramid structures 110 can reflect more incident light, thereby improving photoelectric conversion efficiency. The proportion of the first type of pyramid structure 110 can be 60%, 65%, 70%, 75%, or 80%.

[0050] In some embodiments, reference Figure 2 The first base length L1 is 1μm to 2μm, and the first height H1 is 0.8μm to 1.8μm. The first base length can be 1μm, 1.2μm, 1.4μm, 1.6μm, 1.8μm, or 2μm. The first height H1 can be 0.8μm, 1μm, 1.2μm, 1.3μm, 1.5μm, 1.7μm, or 1.8μm.

[0051] The first base length is within any of the above ranges, the first height H1 is within any of the above ranges, and both the first base length L1 and the first height H1 are relatively large. The first type of pyramid structure 110 formed is a large pyramid structure that can provide more reflective surfaces, so that the incident light undergoes multiple internal reflections through these reflective surfaces. This can collect more wavelengths and ranges of incident light, and reduce the reflection of incident light, thereby reducing optical losses and improving the photoelectric conversion efficiency of solar cells.

[0052] In some embodiments, the ratio of the first base length L1 to the first height H1 is a first ratio. The first ratio can be 1 to 1.2. For example, the first ratio can be 1, 1.03, 1.05, 1.1, 1.15, or 1.2.

[0053] In some embodiments, reference Figure 2 The first type of pyramid structure 110 includes a continuous first arc surface 111, a first outer wall surface 112 and a third arc surface 113, with the first outer wall surface 112 connected to the first arc surface 111 and the third arc surface 113.

[0054] It should be noted that the first arc surface 111, the third arc surface 113, and the second arc surface 121 and the fourth arc surface 123 of the second type of pyramid structure 120 described later refer to the fact that the outer wall surface of the pyramid structure is not a straight surface, but a curved surface. From the left view, front view, rear view, and right view, it appears as an arc; from the top view and bottom view, it appears as the base structure of the pyramid, approximately a parallelogram. Figure 2 and Figure 3 This is an enlarged view of the front view.

[0055] In some embodiments, the first arc surface 111 has a first radius of curvature R1, which is 30nm to 100nm. The first radius of curvature R1 can be 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm or 100nm.

[0056] In some embodiments, the first arc surface 111 has a first curvature θ1, which is 70.5°±3°. The first curvature θ1 can be 67.5°, 68°, 69°, 70°, 71°, 72°, 73° or 73.5°.

[0057] In some embodiments, the third arc surface 113 is connected to the surface 4 of the substrate, and the third arc surface 113 has a third radius of curvature R3, which is 10nm to 50nm. The third radius of curvature R3 can be 10nm, 20nm, 30nm, 40nm, or 50nm.

[0058] In some embodiments, the third arc surface 113 has a third curvature θ3, which is 60° to 130°. The third curvature θ3 can be 60°, 70°, 80°, 90°, 100°, 110°, 120° or 130°.

[0059] In some embodiments, the first radius of curvature R1 is greater than the third radius of curvature R3.

[0060] The second type of pyramid structure 120 is a type of velvet structure, which can improve the internal reflectivity of incident light.

[0061] In some embodiments, the apex of the second type of pyramid structure 120 is also rounded to form the morphological features of the second arc surface 121, which can improve passivation performance and increase contact area.

[0062] In some embodiments, the total area of ​​the projected area of ​​the second type of pyramid structure 120 onto the base 100 is the second area. The ratio between the second area and the surface area of ​​the base, i.e., the proportion of the second type of pyramid structure 120, is 10% to 40%. The proportion of the second type of pyramid structure 120 can be 10%, 15%, 20%, 25%, 30%, 35%, or 40%.

[0063] The ratio of the first area to the second area is 1.5 to 4. Thus, the proportion of the first type of pyramid structure 110 is relatively large, while the proportion of the second type of pyramid structure 120 is relatively small. The first type of pyramid structure 110 has a higher height, thereby emitting incident light and increasing internal emissivity. The ratio of the first area to the second area can be 1.5, 1.8, 2, 2.3, 2.8, 3.2, 3.8, or 4.

[0064] In some embodiments, reference Figure 3 The second base length L2 is 0.1μm to 0.2μm, and the second height H2 is 0.09μm to 0.2μm.

[0065] The ratio of the second base length L2 to the second height H2 is the second ratio value. The second ratio value can be 0.8 to 1, excluding 1, for example, 0.8, 0.85, 0.9, 0.95 or 0.99.

[0066] In some embodiments, the first ratio is greater than the second ratio. Thus, the tilt angle of the first type of pyramid structure 110 is lower than that of the second type of pyramid structure 120, which can improve the performance of the passivation layer deposited on the first type of pyramid structure 110.

[0067] In some embodiments, reference Figure 3 The second type of pyramid structure 120 includes a continuous second arc surface 121, a second outer wall surface 122 and a fourth arc surface 123, with the second outer wall surface 122 connected to the second arc surface 121 and the fourth arc surface 123.

[0068] In some embodiments, the second arc surface 121 has a second radius of curvature R2, which is 5 nm to 30 nm.

[0069] In some embodiments, the second arc surface 121 has a second curvature θ2, which is 68°±3°.

[0070] In some embodiments, the fourth arc surface 123 is connected to the substrate surface, and the fourth arc surface 123 has a fourth radius of curvature R4, which is 100nm to 500nm.

[0071] In some embodiments, the fourth arc surface 123 has a fourth curvature θ4, which is 60° to 130°. The fourth curvature θ4 can be 60°, 70°, 80°, 90°, 100°, 110°, 120° or 130°.

[0072] In some embodiments, the third radius of curvature R3 is less than or equal to the fourth radius of curvature R4.

[0073] In some embodiments, the second radius of curvature R2 is smaller than the fourth radius of curvature R4.

[0074] Continue to refer to Figure 1 The substrate also includes an emitter 102, the surface of which has a first type of pyramid structure 110 and a second type of pyramid structure 120.

[0075] Emitter 102 is used to generate a built-in electric field and selectively collect charge carriers. The built-in electric field drives the separation of photogenerated electron-hole pairs, with electrons moving towards the n-region (emitter 102 or base region) and holes moving towards the p-region, forming a photocurrent.

[0076] In some embodiments, the emitter 102 is doped with a first dopant element, the doping type of which differs from that of the dopant element in the substrate 100. In one example, the substrate 100 is doped with an N-type dopant element, and the emitter 102 is doped with a P-type dopant element. In another example, the substrate 100 is doped with a P-type dopant element, and the emitter 102 is doped with an N-type dopant element.

[0077] In some embodiments, the passivation layer 131 can be a single-layer structure or a stacked structure, and the material of the passivation layer 131 can be one or more of the following materials: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0078] In some embodiments, a passivation layer 131 covers the first type of pyramid structure 110 and the second type of pyramid structure 120, and the passivation layer 131 is located on the emitter 102.

[0079] Continue to refer to Figure 1 The solar cell also includes a first electrode 141, which is located on the passivation layer 131 and electrically connected to the emitter 102.

[0080] The solar cell also includes a back surface field 103, which is located on the side of the substrate 100 away from the emitter 102.

[0081] The solar cell also includes: a back passivation layer 132, which is located on the surface of the back surface field 103; and a second electrode 142, which is located on the surface of the back passivation layer 132 and electrically connected to the back surface field 103.

[0082] In some embodiments, the material of the back passivation layer 132 may be the same as the material of the passivation layer 131. The material of the first electrode 141 is the same as the material of the second electrode 142.

[0083] In the technical solution provided by this embodiment of the utility model, different types of first-type pyramid structures 110 and second-type pyramid structures 120 are provided, and both the first-type pyramid structure 110 and the second-type pyramid structure 120 are designed with rounded corners to form a first arc surface 111 and a second arc surface 121, respectively. This can improve the density of the passivation layer 131, thereby improving the passivation performance. Secondly, the first radius of curvature R1 is greater than the second radius of curvature R2. For large pyramid structures, a large first radius of curvature R1 means that the first curvature corresponding to the first arc surface 111 of the first-type pyramid structure 110 is small, and the degree of curvature is small, thereby reducing the sharp corner effect caused by the large pyramid. For small pyramids, their height is low, and the second radius of curvature R2 is small, meaning that the second curvature corresponding to the second arc surface 121 of the second-type pyramid structure 120 is large, and the degree of curvature is large. The small height has less impact on the passivation layer 131, and the larger specific surface area resulting from the larger degree of curvature can improve the internal reflectivity and the subsequent contact performance with the first electrode 141.

[0084] Accordingly, another embodiment of the present invention provides a method for preparing a solar cell, which is used to prepare the solar cell provided in the above embodiment. The same or corresponding technical features as those in the above embodiment will not be described in detail here.

[0085] Figure 4 This is a schematic diagram of an initial substrate provided in a method for fabricating a solar cell according to an embodiment of the present invention.

[0086] refer to Figure 4 The preparation method includes: providing an initial substrate 10.

[0087] The initial substrate 10 is made of elemental semiconductor material or compound semiconductor material.

[0088] Figure 5 This is a schematic diagram illustrating the formation of a first initial pyramid structure and a second initial pyramid structure in a method for fabricating a solar cell according to an embodiment of the present invention. Figure 6An electron microscope image of a method for fabricating a solar cell according to an embodiment of the present invention, showing the formation of a first initial pyramid structure and a second initial pyramid structure.

[0089] refer to Figure 5 The preparation method includes: forming a texturing process to form a first initial pyramid structure 11 and a second initial pyramid structure 12. The surface 1 of the initial substrate is a reference plane.

[0090] In some embodiments, the texturing process may include conventionally selected methods such as solution texturing, laser texturing, and ion texturing.

[0091] refer to Figure 6 The first initial pyramid structure 11 has a apex 13, and the surface of the first initial pyramid structure 11 has a rough morphology 14.

[0092] In some embodiments, the first initial pyramid structure 11 has a third base length and a third height, the third base length being in the range of 1 μm to 2 μm, the third height being in the range of 1 μm to 2 μm, and the emissivity being 8% to 13%.

[0093] In some embodiments, the second initial pyramid structure 12 has a fourth base length and a fourth height, the fourth base length being in the range of 0.1 μm to 0.2 μm, the fourth height being in the range of 0.1 μm to 0.2 μm, and the emissivity being 7% to 12%.

[0094] Figure 7 This is a schematic diagram of a structure for forming doped silicon glass in a method for preparing a solar cell according to an embodiment of the present invention. Figure 8 An electron microscope image of a method for fabricating a solar cell according to an embodiment of the present invention, showing the formation of doped silicon glass.

[0095] refer to Figure 7 and Figure 8 The preparation method includes: doping an initial substrate 10 to form an emitter 102, the surface of which has a doped silicon glass 101.

[0096] In some embodiments, doping can be performed by tubular diffusion. BCl3 or BBr3 is used as the boron diffusion source, with a flow rate of 100 sccm to 200 sccm, and the oxygen flow rate is 300 sccm to 1000 sccm, while the temperature is controlled at 900℃ to 1100℃.

[0097] The resulting emitter has a sheet resistance of 50 ohm mm / sq to 400 ohm mm / sq. The emitter surface is covered with doped silicon glass, specifically borosilicate glass (BSG), with a thickness of 30 nm to 150 nm. The surface concentration of the emitter is 1E18 cm⁻¹. -3 ~1E20cm -3 The junction depth of the emitter is 0.3μm to 2μm.

[0098] In other embodiments, POCl3 is used as the phosphorus source with a flow rate of 100 sccm to 200 sccm, the oxygen flow rate is 300 sccm to 1000 sccm, and the temperature is controlled at 800℃ to 1000℃.

[0099] The sheet resistance of the formed emitter is 30 ohm mm / sq to 100 ohm mm / sq. The emitter surface is covered with doped silicon glass, specifically doped phosphorus silicate glass (PSG), with a PSG thickness of 30 nm to 100 nm. The surface concentration of the emitter is 1E18 cm⁻¹. -3 ~1E20cm -3 The junction depth of the emitter is 0.3μm to 2μm.

[0100] refer to Figure 1 Remove doped silicon boron glass.

[0101] The preparation method includes: preparing HF (hydrofluoric acid) with a concentration of 5%–10%, processing for 100–200 seconds at room temperature, removing BSG or PSG, exposing the silicon surface, and continuing to etch the substrate with the etching solution. This reduces the surface roughness of the textured surface, and the sharp corners at the interfaces between the pyramid apex, base, and slope become rounded corners. The reflectivity of the textured surface increases to 9%–14%. The first height of the first type of pyramid structure 110 is 0.8 μm–1.8 μm, and the first base length L1 is 1 μm–2 μm; the second height of the second pyramid structure is 0.09 μm–0.2 μm, and the second base length is 0.1 μm–0.2 μm.

[0102] Continue to refer to Figure 1 The preparation method includes: forming a back surface field 103, wherein the back surface field 103 is located on the side of the substrate 100 away from the emitter 102.

[0103] Continue to refer to Figure 1 The preparation method includes: forming a passivation layer 131, which covers the first type of pyramid structure 110 and the second type of pyramid structure 120, and the passivation layer 131 is located on the emitter 102.

[0104] In some embodiments, while forming the passivation layer 131, a back passivation layer 132 is formed, which is located on the surface of the back surface field 103.

[0105] In some embodiments, the passivation layer 131 and / or the back passivation layer 132 can be a single-layer structure or a stacked structure. The material of the passivation layer 131 can be one or more of the following: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, or aluminum oxide. The material of the back passivation layer 132 can be one or more of the following: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0106] Continue to refer to Figure 1 The fabrication method includes: forming a first electrode 141 and a second electrode 142, wherein the first electrode 141 is located on the passivation layer 131 and electrically connected to the emitter 102; and the second electrode 142 is located on the surface of the back passivation layer 132 and electrically connected to the back surface field 103.

[0107] Accordingly, according to some embodiments of the present invention, another aspect of the present invention provides a photovoltaic module, including the solar cell provided in the above embodiments and the solar cell prepared by the preparation method of the solar cell provided in the above embodiments, with the same or corresponding technical features as the above embodiments, which will not be described in detail here.

[0108] Figure 9 This is a schematic diagram of a photovoltaic module according to another embodiment of the present invention.

[0109] refer to Figure 9 The photovoltaic module includes: a battery string, which is composed of a plurality of solar cells as described in any 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 facing away from the battery string.

[0110] Specifically, in some embodiments, multiple solar cells can be electrically connected to each other via a connecting member 318, which is welded to the main grid on the solar cell. The main grid includes a main electrode electrically connected to the electrode 104 and a main electrode electrically connected to the back electrode 106.

[0111] In some embodiments, there is no spacing between the solar cells, meaning that the solar cells overlap each other.

[0112] In some embodiments, the connecting member 318 is welded to a sub-grid on the battery cell, the sub-grid including an electrode 104 and a back electrode 106.

[0113] In some embodiments, the encapsulating film 31 includes a first encapsulating layer and a second encapsulating layer. The first encapsulating layer covers one of the front or back sides of the solar cell, and the second encapsulating layer covers the other of the front or back sides of the solar cell. Specifically, at least one of the first encapsulating layer or the second encapsulating layer can be an organic encapsulating film such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate copolymer (EVA) film, polyvinyl octene coelastomer (POE) film, or polyethylene terephthalate (PET) film.

[0114] It is worth noting that the first encapsulation layer and the second encapsulation layer still have a dividing line before lamination. After lamination, the photovoltaic module will no longer have the concept of a first encapsulation layer and a second encapsulation layer. That is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film 31.

[0115] 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 encapsulation layer and the second cover plate being opposite to the second encapsulation layer; or the first cover plate being opposite to one side of the solar cell and the second cover plate being opposite to the other side of the solar cell.

[0116] Those skilled in the art will understand that the above embodiments are specific examples of implementing this utility model, and in practical applications, various changes can be made in form and detail without departing from the spirit and scope of this utility model. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this utility model; therefore, the protection scope of this utility model should be determined by the scope defined in the claims.

Claims

1. A solar cell, characterized in that, include: The base; the surface of the base includes at least a first type of pyramid structure and a second type of pyramid structure, wherein the first base side length of the first type of pyramid structure is greater than the second base side length of the second type of pyramid structure; and / or, the first height of the first type of pyramid structure is greater than the second height of the second type of pyramid structure; Wherein, the side of the first type of pyramid structure away from the base includes a first arc surface with a first radius of curvature, and the side of the second type of pyramid structure away from the base includes a second arc surface with a second radius of curvature, wherein the first radius of curvature is greater than the second radius of curvature; A passivation layer is located on the surface of the substrate, and the passivation layer covers the first type of pyramid structure and the second type of pyramid structure.

2. The solar cell according to claim 1, characterized in that, The first type of pyramid structure includes a first outer wall surface and a third arc surface, the first outer wall surface being connected to the first arc surface and the third arc surface, the third arc surface being connected to the base surface, and the third arc surface having a third radius of curvature; the second type of pyramid structure includes a second outer wall surface and a fourth arc surface, the second outer wall surface being connected to the second arc surface and the fourth arc surface, the fourth arc surface being connected to the base surface, and the fourth arc surface having a fourth radius of curvature; the third radius of curvature is less than or equal to the fourth radius of curvature.

3. The solar cell according to claim 2, characterized in that, The first radius of curvature is greater than the third radius of curvature; the second radius of curvature is less than the fourth radius of curvature.

4. The solar cell according to claim 1, characterized in that, The total area of ​​the orthographic projection of the first type of pyramid structure onto the base is the first area, and the total area of ​​the orthographic projection of the second type of pyramid structure onto the base is the second area. The ratio of the first area to the second area is 1.5 to 4.

5. The solar cell according to claim 1, characterized in that, The ratio of the first base length to the first height is a first ratio, and the ratio of the second base length to the second height is a second ratio; the first ratio is greater than the second ratio.

6. The solar cell according to claim 1 or 5, characterized in that, The length of the first base is 1μm to 2μm, and the first height is 0.8μm to 1.8μm.

7. The solar cell according to claim 1 or 5, characterized in that, The second base length is 0.1μm to 0.2μm, and the second height is 0.09μm to 0.2μm.

8. The solar cell according to claim 1, characterized in that, The first radius of curvature is 30nm to 100nm.

9. The solar cell according to claim 1, characterized in that, The second radius of curvature is 5nm to 30nm.

10. A photovoltaic module, characterized in that, include: A battery string, comprising multiple solar cells connected together as described in any one of claims 1 to 9; 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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