Solar cell and photovoltaic module

Abstract

To provide a solar cell and a photovoltaic module that are advantageous in improving the photoelectric conversion efficiency.SOLUTION: A solar cell includes a substrate 200 having a front surface 21 and a back surface 22 disposed facing each other, a first polysilicon doping layer 212 and a second polysilicon doping layer 222 existing on the back surface 22, and a first electrode 214 and a second electrode 224. Here, the inside of the first polysilicon doping layer 212 is doped with N-type dopant ion, a surface of the first polysilicon doping layer 212 has a first projection structure, the inside of the second polysilicon doping layer 222 is doped with P-type dopant ion, the first polysilicon doping layer 212 and the second polysilicon doping layer 222 are insulated, a surface of the second polysilicon doping layer 222 has a second projection structure, and the thickness of the first projection structure is larger than the thickness of the second projection structure, and the thickness of the first polysilicon doping layer 212 is less than or equal to the thickness of the second polysilicon doping layer 222.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The present application relates to the field of photovoltaics, and more particularly to solar cells and photovoltaic modules. [Background technology]

[0002] A solar cell is a device that converts solar light energy into electrical energy. Solar cells utilize the principle of photovoltaic power to generate carriers, which are then extracted by electrodes, contributing to the efficient use of electrical energy.

[0003] Currently, solar cells mainly include IBC (Interdigitated Back Contact) cells, TOPCON (Tunnel Oxide Passivated Contact) cells, PERC (Passivated Emitter and Rear Cell) cells, and heterojunction cells. The installation and functional definition of different film layers reduces optical loss and reduces the recombination of photogenerated carriers on the surface and inside the silicon substrate, thereby increasing the photoelectric conversion efficiency of solar cells.

[0004] However, currently, the photoelectric conversion efficiency of solar cells is still poor. Summary of the Invention [Problem to be solved by the invention]

[0005] In the embodiments of the present application, a solar cell and a photovoltaic module are provided that are advantageous in improving at least the photoelectric conversion efficiency of the solar cell. [Means for solving the problem]

[0006] According to some embodiments of the present application, in one aspect of the embodiment of the present application, there is provided a solar cell, the solar cell including: a substrate having a front surface and a back surface opposite to each other; a first polysilicon doped layer doped with N-type dopant ions; a second polysilicon doped layer doped with P-type dopant ions; and a first electrode and a second electrode, wherein the first polysilicon doped layer is located on the front surface or the back surface; a first protrusion structure is formed on a surface of the first polysilicon doped layer; the second polysilicon doped layer is located on the back surface and is insulated from the first polysilicon doped layer; a second protrusion structure is formed on a surface of the second polysilicon doped layer; a thickness of the first protrusion structure is greater than a thickness of the second protrusion structure; a thickness of the first polysilicon doped layer including the first protrusion structure is equal to or less than a thickness of the second polysilicon doped layer including the second protrusion structure; the first electrode is in electrical contact with the first polysilicon doped layer; and the second electrode is in electrical contact with the second polysilicon doped layer.

[0007] In some embodiments, the surface roughness of the first polysilicon doped layer including the first protruding structure is greater than the surface roughness of the second polysilicon doped layer including the second protruding structure.

[0008] In some embodiments, the surface roughness of the first polysilicon doped layer including the first protrusion structures ranges from 10 nm to 30 nm.

[0009] In some embodiments, the surface roughness of the second polysilicon doped layer including the second protrusion structures ranges from 0 nm to 20 nm.

[0010] In some embodiments, the thickness of the first protrusion structure ranges from 30 nm or less.

[0011] In some embodiments, the thickness range of the second protrusion structure is 20 nm or less.

[0012] In some embodiments, the range of one dimension of the first protrusion structure is 0 μm to 500 μm.

[0013] In some embodiments, the range of one dimension of the second protrusion structure is 0 um to 300 um.

[0014] In some embodiments, the thickness of the second polysilicon doped layer including the second protrusion structure ranges from 100 nm to 400 nm.

[0015] In some embodiments, the thickness of the first polysilicon doped layer including the first protrusion structure ranges from 50 nm to 300 nm.

[0016] In some embodiments, the back surface includes an N region and a P region, the first polysilicon doped layer being located in the N region and the second polysilicon doped layer being located in the P region.

[0017] In some embodiments, the cross-sectional shape of at least one of the first protruding structure or the second protruding structure comprises a parabola, a sector, a trapezoid, or a near-trapezoid.

[0018] According to some embodiments of the present application, in another aspect of the embodiments of the present application, a photovoltaic module is provided, which includes a cell string formed by connecting a plurality of solar cells described in any one of the above embodiments, a sealing adhesive film for covering a surface of the cell string, and a cover plate for covering a surface of the sealing adhesive film away from the cell string. [Effects of the Invention]

[0019] The technical solutions provided in the embodiments of the present application have at least the following advantages:

[0020] In the solar cell provided in this embodiment, the first polysilicon doping layer is located on the back or front side, and the second polysilicon doping layer is located on the back side, which indicates two types of solar cell: IBC cell and TOPCon cell. In this embodiment, the thickness of the first polysilicon doping layer including the first protrusion structure is limited to be thinner than the thickness of the second polysilicon doping layer including the second protrusion structure. Furthermore, since the N-type polysilicon doping layer is donor-type, the crystalline silicon grains of the formed first polysilicon doping layer are small, the airtightness between the crystalline silicon grains is strong, and the thickness of the formed film layer is small. Conversely, if the P-type polysilicon doping layer is acceptor-type and has good compatibility with the substrate, the crystalline silicon grains of the P-type polysilicon doping layer are large, and the thickness of the formed second polysilicon doping layer is thick. In this case, the second polysilicon doping layer includes the second protrusion structure.

[0021] The first polysilicon doped layer is located on the front or back surface, and the thickness of the first protrusion structure is greater than the thickness of the second protrusion structure. When the first polysilicon doped layer is located on the front surface, the internal reflection of the first polysilicon doped layer and the contact performance between the first polysilicon doped layer and the first electrode can be improved. When the second protrusion structure of the second polysilicon doped layer is thin, the second polysilicon doped layer can improve the passivation performance of the film layer located thereon. [Brief explanation of the drawings]

[0022] One or more embodiments are illustratively described in corresponding figures in the accompanying drawings, but these illustrative descriptions are not intended to limit the embodiments, and unless otherwise specified, the figures in the accompanying drawings are not limited to scale. In order to more clearly explain the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below 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 effort. [Figure 1] FIG. 1 is a diagram showing the structure of a solar cell provided in one embodiment of the present application. [Figure 2] FIG. 2 is a diagram showing a first type cross-sectional structure along the A1-A2 cross section of FIG. [Figure 3] FIG. 3 is a diagram illustrating the structure of the first polysilicon doped layer in the solar cell provided in one embodiment of the present application. [Figure 4] FIG. 4 is an electron microscope photograph of a cross section of the second polysilicon doped layer in a solar cell provided in one embodiment of the present application. [Figure 5] FIG. 5 is a locally enlarged view of the first protrusion structure in the F1 portion in FIG. [Figure 6] FIG. 6 is a diagram illustrating the structure of the second polysilicon doped layer in the solar cell provided in one embodiment of the present application. [Figure 7] FIG. 7 is an electron microscope photograph of a cross section of the second polysilicon doped layer in a solar cell provided in one embodiment of the present application. [Figure 8] FIG. 8 is a locally enlarged view of the second protrusion structure in the portion F2 in FIG. [Figure 9] FIG. 9 is a diagram showing a second type of cross-sectional structure along the A1-A2 cross section of FIG. [Figure 10] FIG. 10 is a diagram showing the structure of a solar cell provided in one embodiment of the present application. [Figure 11] FIG. 11 is a diagram showing a first type cross-sectional structure along the B1-B2 cross section of FIG. [Figure 12] FIG. 12 is a diagram showing the structure of a photovoltaic module provided in another embodiment of the present application. [Figure 13] FIG. 13 is a diagram showing a cross-sectional structure along the M1-M2 cross section of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0023] As can be seen from the background art, the photoelectric conversion efficiency of conventional solar cells is poor.

[0024] In the solar cell provided in this embodiment, the first polysilicon doping layer is located on the back or front side, and the second polysilicon doping layer is located on the back side, which indicates two types of solar cell: IBC cell and TOPCon cell. In this embodiment, the thickness of the first polysilicon doping layer including the first protrusion structure is limited to be thinner than the thickness of the second polysilicon doping layer including the second protrusion structure. Furthermore, since the N-type polysilicon doping layer is donor-type, the crystalline silicon grains of the formed first polysilicon doping layer are small, the airtightness between the crystalline silicon grains is strong, and the thickness of the formed film layer is small. Conversely, if the P-type polysilicon doping layer is acceptor-type and has good compatibility with the substrate, the crystalline silicon grains of the P-type polysilicon doping layer are large, and the thickness of the formed second polysilicon doping layer is thick, where the second polysilicon doping layer includes the second protrusion structure.

[0025] The first polysilicon doped layer is located on the front or back surface, and the thickness of the first protrusion structure is greater than the thickness of the second protrusion structure. When the first polysilicon doped layer is located on the front surface, the internal reflection of the first polysilicon doped layer and the contact performance between the first polysilicon doped layer and the first electrode can be improved. When the second protrusion structure of the second polysilicon doped layer is thin, the second polysilicon doped layer can improve the passivation performance of the film layer located thereon.

[0026] Hereinafter, each embodiment of the present application will be described in detail in conjunction with the drawings. However, as will be understood by those skilled in the art, although many technical details are proposed in the embodiments of the present application to help readers better understand the present application, the technical solutions claimed for protection in the embodiments of the present application can be realized without these technical details and various changes and modifications based on the following embodiments.

[0027] FIG. 1 is a diagram showing the structure of a solar cell provided in one embodiment of the present application. FIG. 2 is a diagram showing a first cross-sectional structure along the A1-A2 cross section of FIG. 1. FIG. 3 is a diagram showing the structure of a first polysilicon doped layer in a solar cell provided in one embodiment of the present application. FIG. 4 is an electron microscope photograph of a cross section of a second polysilicon doped layer in a solar cell provided in one embodiment of the present application. FIG. 5 is a locally enlarged view of a first protrusion structure in part F1 in FIG. 4. FIG. 6 is a diagram showing the structure of a second polysilicon doped layer in a solar cell provided in one embodiment of the present application. FIG. 7 is an electron microscope photograph of a cross section of a second polysilicon doped layer in a solar cell provided in one embodiment of the present application. FIG. 8 is a locally enlarged view of a second protrusion structure in part F2 in FIG. 7.

[0028] As shown in FIGS. 1 and 2 , according to some embodiments of the present application, in one aspect of the present embodiments, a solar cell is provided, the solar cell including: a substrate 100 having a front surface 11 and a back surface 12 opposite to each other; a first polysilicon doped layer 112 doped with N-type dopant ions; a second polysilicon doped layer 122 doped with P-type dopant ions; a first electrode 114; and a second electrode 124, wherein the first polysilicon doped layer 112 is located on the front surface 11; a first protrusion structure 1120 (see FIG. 3 ) is formed on the surface of the first polysilicon doped layer 112; and a second electrode 124. 12, the first polysilicon doped layer 112 and the second polysilicon doped layer 122 are insulated from each other, the second polysilicon doped layer 122 has a second protrusion structure 1220 (see FIG. 6 ) on the surface thereof, the thickness of the first protrusion structure 1120 is greater than the thickness of the second protrusion structure 1220, the thickness of the first polysilicon doped layer 112 including the first protrusion structure 1120 is equal to or less than the thickness of the second polysilicon doped layer 122 including the second protrusion structure 1220, the first electrode 114 is in electrical contact with the first polysilicon doped layer 112, and the second electrode 124 is in electrical contact with the second polysilicon doped layer 122.

[0029] In some embodiments, the material of the substrate 100 may be an elemental semiconductor material. Specifically, the elemental semiconductor material may be composed of a single element, such as silicon or germanium. Here, the elemental semiconductor material may be in a monocrystalline state, a polycrystalline state, an amorphous state, or a microcrystalline state (a state having both a monocrystalline state and an amorphous state is called a microcrystalline state), and for example, silicon may be at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon.

[0030] In some embodiments, the material of 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 gallide, perovskites, cadmium telluride, copper indium selenide, etc. Substrate 100 may be a sapphire substrate, a silicon-on-insulator substrate, or a germanium-on-insulator substrate.

[0031] In some embodiments, the substrate 100 may be an N-type semiconductor substrate or a P-type semiconductor substrate. An N-type semiconductor substrate is doped with an N-type doping element, which may be any of Group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). A P-type semiconductor substrate is doped with a P-type doping element, which may be any of Group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0032] In some embodiments, the substrate 100 has a front surface 11 and a back surface 12 that are oppositely disposed. The solar cell is a single-sided cell, with the front surface being used as the light-receiving surface to receive incident light and the back surface being used as the backlight surface. Here, the backlight surface can also receive incident light, but the efficiency of receiving incident light is weaker than that of the light-receiving surface.

[0033] In some embodiments, the solar cell further includes a first dielectric layer 111 located between the substrate 100 and the first polysilicon doped layer 112. A passivation contact structure is formed between the first dielectric layer 111 and the first polysilicon doped layer 112, and the first polysilicon doped layer 112 can form a band bending at the surface of the substrate 100. The first dielectric layer 111 generates an asymmetric offset in the bands at the surface of the substrate 100, so that the potential barrier for majority carriers among the carriers is lower than the potential barrier for minority carriers among the carriers. This allows majority carriers to easily pass through the first dielectric layer 111, thereby enabling quantum tunneling, but minority carriers have difficulty passing through the first dielectric layer 111, thereby realizing selective carrier transport.

[0034] The first 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 first dielectric layer 111 increases the interface state density on the front surface of the substrate 100, and the increased interface state density promotes the recombination of photogenerated carriers. By positioning the first dielectric layer 111 on the front surface of the substrate 100, the first dielectric layer 111 can exhibit a chemical passivation effect on the surface of the substrate 100. Specifically, by saturating the dangling bonds of the substrate 100, the defect state density of the substrate 100 is reduced, the number of recombination centers in the substrate 100 is reduced, the carrier recombination rate is reduced, and the backing factor, short-circuit current, and open-circuit voltage of the solar cell are increased, thereby improving the photoelectric conversion efficiency of the solar cell.

[0035] In some embodiments, the thickness of the first dielectric layer 111 is 0.5 nm to 5 nm. The thickness of the first dielectric layer 111 ranges from 0.5 nm to 1.3 nm, from 1.3 nm to 2.6 nm, from 2.6 nm to 4.1 nm, or from 4.1 nm to 5 nm. When the thickness of the first dielectric layer 111 is within any of the above ranges, the thickness of the first dielectric layer 111 is thin, so majority carriers can easily quantum tunnel through the first dielectric layer 111, but minority carriers have difficulty passing through the first dielectric layer 111, thereby realizing selective carrier transport.

[0036] In some embodiments, the first polysilicon doped layer 112 exhibits a field passivation effect, specifically, by forming an electrostatic field at the surface of the substrate 100 that is directed toward the interior of the substrate 100, causing minority carriers to escape from the interface, reducing the minority carrier concentration, and slowing down the carrier recombination rate at the interface of the substrate 100, thereby increasing the open circuit voltage, short circuit current, and backing factor of the solar cell and improving the photoelectric conversion efficiency of the solar cell.

[0037] The first polysilicon doped layer 112 may be doped with the same type of doping element as the substrate 100. For example, if the doping element of the substrate 100 is N-type, the first polysilicon doped layer 112 is doped with N-type doping element.

[0038] In some embodiments, the first polysilicon doped layer 112 is doped with an N-type doping element, which unifies the grains of the first polysilicon doped layer 112 to form a single crystal structure, and the first polysilicon doped layer 112 with the N-type doping element has small grain sizes and numerous and uniform grain boundaries.

[0039] As shown in FIG. 3, the first polysilicon doped layer 112 has a plurality of first protrusion structures 1120, which may be pyramidal structures or protrusion structures of any shape. The first protrusion structures 1120 are also part of the first polysilicon doped layer 112. The first protrusion structures 1120 mean that there is an uneven structure on the surface of the first polysilicon doped layer 112. The uneven shape can be used as a light trapping structure to increase the incident light of the solar cell and improve the photoelectric conversion efficiency of the solar cell.

[0040] The first protrusion structure 1120 may be formed by gathering a plurality of crystal grains constituting the first polysilicon doped layer 112. The first protrusion structure 1120 may have a certain form of the first polysilicon doped layer 112. Here, the first polysilicon doped layer 112 includes a plurality of first silicon crystal grains, and one or more of the first silicon crystal grains gather to form the first protrusion structure 1120, and the surfaces of the plurality of first silicon crystal grains constitute the surface of the first polysilicon doped layer 112 having a first roughness.

[0041] In the process of forming the first polysilicon doping layer, silicon atoms are arranged in the form of a diamond crystal lattice to form many crystal nuclei, which then grow into crystal grains with different crystal plane orientations, which then combine and crystallize to form polycrystalline silicon. Here, the first silicon crystal grains refer to the crystal grains with different crystal plane orientations that make up the polycrystalline silicon.

[0042] In some embodiments, the cross-sectional shape of the first protruding structure 1120 comprises a parabola, a sector, a trapezoid, or a near-trapezoid.

[0043] The cross-sectional morphology of the first polysilicon doped layer can be intuitively seen from the cross-sectional electron microscope photograph of Figure 4. The first polysilicon doped layer is composed of a plurality of first silicon crystal grains, and the uneven surface of the first polysilicon doped layer 112 is constructed by stacking a plurality of first silicon crystal grains, so that the surface of the first polysilicon doped layer 112 has a first roughness and a first protrusion structure 1120.

[0044] In some embodiments, the grain size of the first silicon crystal grains is in the range of 10 nm to 300 nm. For example, the grain size of the first silicon crystal grains may be 10 nm to 53 nm, 53 nm to 95.3 nm, 95.3 nm to 138.2 nm, 138.2 nm to 200.6 nm, 200.6 nm to 248 nm, or 248 nm to 300 nm. The grain size of the first silicon crystal grains should be set within any of the above ranges so that the surface roughness of the first silicon crystal grains is increased. When the grain size of the first silicon crystal grains is within any of the above ranges, the stability between the first silicon crystal grains is good, and crystalline deformation is unlikely to occur in the first polysilicon doped layer 112. In addition, if the grain size of the first silicon crystal grains is within the above range, the stress of the first polysilicon doped layer 112 on the first dielectric layer 111 and the first passivation layer 113 is small, and the film layer performance between the first polysilicon doped layer 112 and the first dielectric layer 111 and between the first polysilicon doped layer 112 and the first passivation layer can be improved.

[0045] 4, in some embodiments, the first roughness range of the surface of the first polysilicon doped layer 112 with the first protrusion structures 1120 is 10 nm to 30 nm, or the first roughness range may be 10 nm to 13.2 nm, 13.2 nm to 16 nm, 16 nm to 22 nm, 22 nm to 25 nm, or 25 nm to 30 nm.

[0046] Here, the "roughness" in the "first roughness" and "second roughness" refers to the arithmetic mean of the absolute values ​​of the vertical deviations of the peaks and valleys within a sampled length (1 μm) from the average horizontal line. Roughness can be measured by the comparative method, light section method, interferometry, and probe scanning method.

[0047] In some embodiments, the thickness h1 of the first protrusion structure 1120 is in the range of 30 nm or less, as shown in Figure 5. Here, the thickness of the first protrusion structure 1120 refers to the average height of the pyramid structures or any protrusion structures that constitute the first protrusion structure.

[0048] 5, the one-dimensional dimension d1 of the first protrusion structure is in the range of 0 μm to 500 μm. For example, the one-dimensional dimension d1 of the first protrusion structure may be 0 μm to 80 μm, 80 μm to 200 μm, 200 μm to 372 μm, 372 μm to 430 μm, or 430 μm to 500 μm. Here, the one-dimensional dimension of the first protrusion structure 1120 refers to the average value of the one-dimensional dimension of the pyramid structure or any protrusion structure that constitutes the first protrusion structure.

[0049] In some embodiments, the thickness of the first polysilicon doped layer 112 with the first protrusion structures 1120 ranges from 50 nm to 300 nm, or from 150 nm to 80 nm, 80 nm to 120 nm, 120 nm to 200 nm, 200 nm to 230 nm, 230 nm to 260 nm, or 260 nm to 300 nm.

[0050] In some embodiments, the density of the first protrusion structures 1120 ranges from 50% to 98%. The density of the first protrusion structures 1120 may refer to the ratio of the area including the first protrusion structures per unit length (1 μm) to the area of ​​the first polysilicon doped layer not including the first protrusion structures.

[0051] 2, the solar cell further includes a second dielectric layer 121 located between the substrate 100 and the second polysilicon doped layer 122. A passivation contact structure is formed between the second dielectric layer 121 and the second polysilicon doped layer 122, and the construction of the second dielectric layer 121 can refer to the construction of the first dielectric layer 111, which will not be described again here.

[0052] In some embodiments, the thickness of the second polysilicon doped layer 122 and the mechanism for forming the passivation contact structure between the second polysilicon doped layer 122 and the substrate 100 can refer to the thickness of the first polysilicon doped layer 112 and the mechanism for forming the passivation contact structure between the first polysilicon doped layer 112 and the substrate 100, which will not be repeated here.

[0053] In some embodiments, the second polysilicon doped layer 122 is doped with a P-type doping element, which has good compatibility with the second dielectric layer 121. For example, when the P-type doping element is B, B can form a B-O bond and a B-Si bond with silicon and oxygen, which results in good contact performance between the second polysilicon doped layer 122 and the second dielectric layer 121 and between the second polysilicon doped layer 122 and the second passivation layer 123, and the surface of the formed second polysilicon doped layer 122 is smooth.

[0054] As shown in FIG. 6, the second polysilicon doped layer 122 has a plurality of second protrusion structures 1220, which may be pyramidal structures or protrusion structures of any shape. The second protrusion structures 1220 are also part of the second polysilicon doped layer 122. The second protrusion structures 1220 refer to an uneven structure on the surface of the second polysilicon doped layer 122. The uneven shape can be used as a light trapping structure to increase the incident light of the solar cell and improve the photoelectric conversion efficiency of the solar cell.

[0055] The second protrusion structure 1220 may be formed by gathering a plurality of crystal grains constituting the second polysilicon doped layer 122. The second protrusion structure 1220 may have a certain form of the second polysilicon doped layer 122. Here, the second polysilicon doped layer 122 includes a plurality of second silicon crystal grains, and one or more second silicon crystal grains gather to form the second protrusion structure 1220, and the surfaces of the plurality of second silicon crystal grains constitute the surface of the second polysilicon doped layer 122 having the second roughness.

[0056] In the process of forming the second polysilicon doped layer 122, silicon atoms are arranged in the form of a diamond crystal lattice to form many crystal nuclei, which then grow into crystal grains with different crystal plane orientations, which then combine and crystallize to form polycrystalline silicon. Here, the second silicon crystal grains refer to the crystal grains with different crystal plane orientations that make up the polycrystalline silicon.

[0057] 7, the cross-sectional electron microscope photograph can be seen intuitively of the cross-sectional morphology of the second polysilicon doped layer 122. The second polysilicon doped layer 122 is composed of a plurality of second silicon crystal grains, and the stacked second silicon crystal grains form the uneven surface of the second polysilicon doped layer 122, so that the surface of the second polysilicon doped layer 122 has a second roughness and a second protrusion structure 1220.

[0058] In some embodiments, the second polysilicon doped layer 122 includes a plurality of second silicon grains, surfaces of the plurality of second silicon grains forming a surface of the second polysilicon doped layer 122 having a second roughness, and the grain size of the first silicon grains is smaller than the grain size of the second silicon grains.

[0059] In some embodiments, the grain size of the second silicon crystal grains is in the range of 100 nm to 900 nm. For example, the grain size of the second silicon crystal grains may be 100 nm to 250 nm, 250 nm to 360 nm, 360 nm to 490 nm, 490 nm to 584 nm, 584 nm to 610 nm, 610 nm to 790 nm, or 790 nm to 900 nm. When the grain size of the second silicon crystal grains is within any of the above ranges, the grain boundaries between the second silicon crystal grains are small, allowing carriers to easily pass through the second polysilicon doped layer 122, thereby increasing the carrier migration speed and contributing to improving battery efficiency.

[0060] Here, the index representing the size of the crystal grains is called the crystal grain size. Common methods of expression include the number of crystal grains per unit volume (ZV), the number of crystal grains per unit area (ZS), and the average line length (or diameter) of the crystal grains. The average line length of the crystal grains refers to the line length of the extension surface in the extension direction of the crystal grains. The crystal grain size in this embodiment may be the average line length of the crystal grains.

[0061] In some embodiments, the first roughness of the surface of the first polysilicon-doped layer 112 including the first protrusion structures 1120 is greater than the second roughness of the surface of the second polysilicon-doped layer 122 including the second protrusion structures 1220. Therefore, based on the difference in morphology between the first polysilicon-doped layer 112 and the second polysilicon-doped layer 122, the surface of the first polysilicon-doped layer 112 with a higher roughness can enhance the internal reflection of incident light and reduce optical loss of the solar cell. Furthermore, the first polysilicon-doped layer 112 can increase the contact area between the first electrode and the first polysilicon-doped layer 112, thereby improving the contact performance and soldering tensile strength of the first polysilicon-doped layer 112. In the case of the second polysilicon doped layer 122 with low roughness, the surface of the second polysilicon doped layer 122 is smooth, the uniformity of the second passivation layer grown thereon is good, and the passivation performance of the second passivation layer is good, so that the recombination defects of the solar cell can be improved.

[0062] In some embodiments, the second roughness range of the surface of the second polysilicon doped layer 122 including the second protrusion structures 1220 is 0 nm to 20 nm, 0 nm to 5 nm, 5 nm to 7.5 nm, 7.5 nm to 11 nm, 11 nm to 15 nm, or 15 nm to 20 nm.

[0063] In some embodiments, the thickness h2 of the second protrusion structure 1220 ranges from 20 nm to less.

[0064] In some embodiments, the range of the first dimension d2 of the second protrusion structure 1220 is 0 um to 300 um, or the range of the first dimension d2 of the second protrusion structure 1220 is 0 um to 80 um, 80 um to 120 um, 120 um to 180 um, 180 um to 250 um, or 250 um to 300 um.

[0065] In some embodiments, the thickness of the second polysilicon doped layer 122 including the second protrusion structures 1220 ranges from 100 nm to 400 nm, from 100 nm to 150 nm, from 150 nm to 230 nm, from 230 nm to 280 nm, from 280 nm to 330 nm, or from 330 nm to 400 nm.

[0066] In some embodiments, the cross-sectional shape of the second protruding structure 1220 comprises a parabola, a sector, a trapezoid, or a near-trapezoid.

[0067] In some embodiments, the thickness of the first polysilicon doped layer 112 including the first protrusion structures 1120 is equal to or less than the thickness of the second polysilicon doped layer 122 including the second protrusion structures 1220. This allows the doping elements in the substrate to diffuse into the first polysilicon doped layer 112 and be collected by the first electrode due to the small thickness of the first polysilicon doped layer 112. The second polysilicon doped layer 122 located on the backside is thicker, reducing the risk of the second electrode burning through the second polysilicon doped layer 122 and diffusing the P-type doping elements into the substrate due to the second polysilicon doped layer 122 being too thin. This avoids the problem of the P-type doping elements in the second polysilicon doped layer 122 accumulating at the substrate interface to form a "dead layer," thereby improving carrier transport efficiency and reducing the generation of carrier recombination centers.

[0068] In addition, the first polysilicon doped layer 112 is located on the front surface, and when the thickness of the first polysilicon doped layer 112 is thin, the first polysilicon doped layer 112 can reduce the parasitic absorption of incident light and reduce the optical loss of the solar cell.

[0069] In some embodiments, the doping type of the first polysilicon doped layer 112 is the same as the doping type of the substrate, and the doping type of the second polysilicon doped layer 122 is different from the doping type of the substrate. That is, if the substrate is doped with an N-type dopant, the solar cell is a back-junction solar cell, and the "junction" refers to a "PN junction." Here, the first polysilicon doped layer 112 is located on the front side of the substrate, and the first polysilicon doped layer 112 and the first dielectric layer provide good passivation for the substrate, reducing the recombination of photo-generated carriers at the front side. The photo-generated carriers then migrate to the back side, where they are separated into majority and minority carriers and are then collected by the first and second electrodes. In addition, the thin thickness of the first polysilicon doped layer 112 further reduces optical loss due to absorption by the first polysilicon doped layer 112 itself.

[0070] In addition, since the first protrusion structures 1120 located on the front first polysilicon doped layer 112 are thick, the light trapping structure formed by the first protrusion structures 1120 can increase the internal reflection of incident light and improve the internal reflectivity of the solar cell.

[0071] In some embodiments, the substrate is doped with an N-type doping element, and N-type batteries have advantages over P-type batteries, such as higher conversion efficiency, lower temperature coefficient, higher bifaciality, and longer carrier lifetime.

[0072] In some embodiments, the doping type of the first polysilicon doped layer 112 and the substrate are reversed, and the doping type of the second polysilicon doped layer 122 and the substrate are the same. That is, the substrate is doped with a P-type dopant, and the solar cell is a front-side junction solar cell. In a front-side junction solar cell, a large amount of sunlight is collected by the substrate, and the sunlight can be separated into majority and minority carriers on the front side of the substrate, thereby avoiding losses that occur when transitioning through a substrate thickness. In the case of a first polysilicon doped layer 112 located on the front side, the first polysilicon doped layer 112 ensures passivation performance for the substrate, and the first polysilicon doped layer 112 has a first protrusion structure 1120, which can enhance internal reflection of incident light. In the case of the second polysilicon doped layer 122 located on the backside, a built-in electric field of high and low junction is formed between the second polysilicon doped layer 122 and the substrate, urging carriers to migrate from the substrate to the second polysilicon doped layer 122 and be collected in the second electrode.

[0073] In some embodiments, the solar cell further includes a first passivation layer 113 covering the surface of the first polysilicon doped layer 112 .

[0074] In some embodiments, the first passivation layer 113 may be a single layer structure or a laminated structure, and the material of the first passivation layer 113 may be one or more of materials such as silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0075] In some embodiments, the solar cell further includes a second passivation layer 123 covering the surface of the second polysilicon doped layer 122. The second passivation layer 123 may have a single layer structure or a multilayer structure, and the material of the second passivation layer 123 may be one or more of materials such as silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0076] In some embodiments, the pitch range in the first direction X between two adjacent first electrodes 114 or two adjacent second electrodes 124 is 0.5 mm to 2 mm. For example, the pitch in the first direction X between the first electrodes 114 and the second electrodes 124 may be 0.5 mm to 0.8 mm, 0.8 mm to 1.15 mm, 1.15 mm to 1.28 mm, 1.28 mm to 1.46 mm, 1.46 mm to 1.68 mm, 1.68 mm to 1.84 mm, or 1.84 mm to 2 mm.

[0077] In some embodiments, the range of the width of the first electrode 114 in the first direction X or the width of the second electrode 124 in the first direction X is 5 μm to 50 μm. For example, the range of the width of the first electrode 114 in the first direction X or the width of the second electrode 124 in the first direction X may be 5 μm to 9 μm, 9 μm to 14 μm, 14 μm to 23 μm, 23 μm to 34 μm, 34 μm to 42 μm, 42 μm to 45 μm, 45 μm to 48 μm, or 48 μm to 50 μm.

[0078] In some embodiments, the first electrode 114 may be formed by sintering a burn-through paste. A method for forming the first electrode 114 includes printing a metal paste on a portion of the surface of the first passivation layer 113 using a screen printing process. The metal paste may include at least one of silver, aluminum, copper, tin, gold, lead, and nickel. The metal paste is then subjected to a sintering process. The metal paste contains a highly corrosive component, such as glass powder. In this manner, during the sintering process, the corrosive component corrodes the first passivation layer 113, and the metal paste penetrates into the first passivation layer 113 and makes electrical contact with the first polysilicon doped layer 112.

[0079] In some embodiments, the second electrode 124 may be formed by sintering a burn-through paste. A method for forming the second electrode 124 includes printing a metal paste on a portion of the surface of the second passivation layer 123 using a screen printing process. The metal paste may include at least one of silver, aluminum, copper, tin, gold, lead, and nickel. The metal paste is then subjected to a sintering process. The metal paste contains a highly corrosive component, such as glass powder. In this manner, during the sintering process, the corrosive component corrodes the second passivation layer 123, and the metal paste penetrates into the second passivation layer 123 and makes electrical contact with the second polysilicon doped layer 122.

[0080] In some embodiments, as shown in FIG. 2 , the front surface of the substrate includes a textured structure 13, which includes a plurality of pyramid structures 101, and the textured structure 13 is a light-trapping structure, and the slope of the textured structure can increase the internal reflection of incident light, improve the absorption utilization rate of the substrate for incident light, and thereby increase the cell efficiency of the solar cell.

[0081] FIG. 9 is a diagram showing a second type of cross-sectional structure along the A1-A2 cross section of FIG. 1. In some embodiments, as shown in FIG. 9, the front surface of the substrate includes a metal region 1 and a non-metal region 2, and the first polysilicon doping layer 112 and the first dielectric layer 111 are located in the metal region 1.

[0082] In some embodiments, the metal region 1 refers to the region where the orthogonal projection of the first electrode 114 on the substrate 100 is located, and the non-metal region 2 refers to the region other than the orthogonal projection of the first electrode 114 on the substrate 100. Here, the area of ​​the metal region 1 is generally set to be larger than the area of ​​the first electrode 114 to ensure that the film layer that the first electrode 114 contacts has a high doping concentration or that the region that the first electrode 114 contacts is the first polysilicon doped layer 112.

[0083] By locating the first polysilicon doped layer 112 in the metal region 1 of the substrate 100, the parasitic absorption of the first polysilicon doped layer in the non-metal region 2 can be reduced, and the photoelectric conversion efficiency of the solar cell can be improved.

[0084] In the solar cell provided in the above embodiment, the surface of the first polysilicon doped layer 112 has a first protrusion structure 1120, and the thickness of the first polysilicon doped layer 112 including the first protrusion structure 1120 is set to be smaller than the thickness of the second polysilicon doped layer 122 including the second protrusion structure 1220. Because the N-type polysilicon doped layer is donor-type, the crystalline silicon grains of the formed first polysilicon doped layer 112 are small, the airtightness between the crystalline silicon grains is strong, and the thickness of the formed film layer is small. Conversely, the P-type polysilicon doped layer is acceptor-type, and the compatibility between the P-type polysilicon doped layer and the substrate is good, the crystalline silicon grains of the P-type polysilicon doped layer are large, and the thickness of the formed second polysilicon doped layer 122 is thick, and here, the second polysilicon doped layer 122 includes the second protrusion structure 1220.

[0085] Furthermore, the thickness of the first protrusion structures 1120 is greater than the thickness of the second protrusion structures 1220, thereby improving the internal reflection of the first polysilicon doped layer 112 and the contact performance between the first polysilicon doped layer 112 and the first electrode 114. The height of the second protrusion structures 1220 of the second polysilicon doped layer 122 is low, so the second polysilicon doped layer 122 can improve the passivation performance of the film layer located thereon.

[0086] Accordingly, this embodiment further provides a solar cell. This embodiment differs from the previous embodiment in that, while the previous embodiment has a first polysilicon doped layer located on the front side and a first passivation layer covering the surface of the first polysilicon doped layer, the solar cell provided in this embodiment has a first polysilicon doped layer located on the back side, the first polysilicon doped layer and the second polysilicon doped layer alternately arranged, and the second passivation layer covering the surfaces of the first polysilicon doped layer and the second polysilicon doped layer. The same or corresponding technical features as those in the previous embodiment will not be repeated here.

[0087] FIG. 10 is a diagram showing the structure of a solar cell provided in another embodiment of the present application, and FIG. 11 is a diagram showing a first type of cross-sectional structure along the B1-B2 cross section of FIG.

[0088] As shown in FIGS. 10 and 11, the solar cell includes a substrate 200 having a front surface 21 and a back surface 22 opposite to each other, a first polysilicon doped layer 212 located on the back surface 22, a second polysilicon doped layer 222 located on the back surface 22, a first electrode 214, and a second electrode 224, wherein the first polysilicon doped layer 212 is doped with N-type dopant ions, the first polysilicon doped layer 212 has a first protrusion structure on the surface thereof, the second polysilicon doped layer 222 is doped with P-type dopant ions, and the first electrode 214 has a second protrusion structure on the surface thereof. The polysilicon doped layer 212 and the second polysilicon doped layer 222 are insulated from each other, the second polysilicon doped layer 222 has a second protrusion structure on its surface, the thickness of the first protrusion structure is greater than the thickness of the second protrusion structure, the thickness of the first polysilicon doped layer 212 including the first protrusion structure is equal to or less than the thickness of the second polysilicon doped layer 222 including the second protrusion structure, the first electrode 214 is in electrical contact with the first polysilicon doped layer 212, and the second electrode 224 is in electrical contact with the second polysilicon doped layer 222.

[0089] In some embodiments, backside surface 22 includes an N region and a P region, with first polysilicon doped layer 212 located in the N region and second polysilicon doped layer 222 located in the P region.

[0090] In some embodiments, the front surface 21 of the substrate 200 comprises a textured structure 23, the textured structure 23 including a plurality of pyramid structures 201, and the textured structure 23 can include regularly shaped pyramid textured structures and irregularly shaped black silicon.

[0091] In some embodiments, the front surface 21 of the substrate comprises a front surface field (FSF) in which the conductivity type of the dopant ions is the same as that of the substrate, and the field passivation effect is used to reduce the surface minority carrier concentration, thereby reducing the surface recombination velocity, lowering the series resistance, and increasing the electron transport capacity.

[0092] In some embodiments, the back surface 22 of the substrate is polished, which refers to a flat surface formed by removing the surface texture using a polishing solution or laser etching. After polishing, the back surface becomes more flat, which increases the reflectivity of long-wavelength light and promotes secondary absorption of incident light, thereby increasing the short-circuit current and reducing the specific surface area of ​​the back surface, reducing recombination on the back surface and improving the passivation effect of the back surface.

[0093] In some embodiments, there is a gap between the P region and the N region, and the second passivation layer is located in the gap.

[0094] In some embodiments, a trench is formed between the P and N regions to provide automatic isolation between regions of different conductivity types, eliminating the possibility that the heavily doped P and N regions on the backside of the IBC cell would form a tunnel junction, causing leakage current and affecting cell efficiency.

[0095] As shown in FIG. 11, the solar cell further includes a first dielectric layer 211 located between the substrate 200 and the first polysilicon doped layer 212, and a second dielectric layer 221 located between the substrate 200 and the second polysilicon doped layer 222.

[0096] In some embodiments, the first roughness range of the surface of the first polysilicon doped layer 212 including the first protrusion structures is between 10 nm and 30 nm.

[0097] In some embodiments, the thickness of the primary protrusion structures ranges from 30 nm or less, and the one-dimensional dimension of the primary protrusion structures ranges from 0 μm to 500 μm.

[0098] In some embodiments, the thickness of the first polysilicon doped layer 212 including the first protrusion structures ranges from 50 nm to 300 nm.

[0099] In some embodiments, the density range of the primary protrusion structures is 50% to 98%.

[0100] In some embodiments, the second roughness range of the surface of the second polysilicon doped layer 222 including the second protrusion structures is between 0 nm and 20 nm.

[0101] In some embodiments, the thickness range of the secondary protrusion structures is 20 nm or less.

[0102] In some embodiments, the range of one dimension of the secondary protrusion structures is 0 μm to 300 μm.

[0103] In some embodiments, the thickness of the second polysilicon doped layer 222 including the second protrusion structures ranges from 100 nm to 400 nm.

[0104] In some embodiments, the solar cell further includes a first passivation layer 213 covering the front surface 21 and a second passivation layer 223 covering the first polysilicon doped layer 212, the second polysilicon doped layer 222 and the gap region gap.

[0105] In some embodiments, the first electrode 214 is located on an N region and the second electrode 224 is located on a P region.

[0106] FIG. 12 is a diagram showing the structure of a photovoltaic module provided in another embodiment of the present application, and FIG. 13 is a diagram showing the cross-sectional structure along the M1-M2 cross section of FIG.

[0107] Accordingly, in accordance with some embodiments of the present application, in some other embodiments of the present application, a photovoltaic module is provided, which may include the solar cell described in the above embodiments, and the same parts as the above embodiments will not be repeated here.

[0108] As shown in Figure 12, the photovoltaic module includes a cell string in which a plurality of solar cells 30 described in any one of the above embodiments are connected by connecting members 309, a sealing adhesive film 37 for covering the surface of the cell string, and a cover plate 38 for covering the surface of the sealing adhesive film 37 away from the cell string.

[0109] Specifically, in some embodiments, the battery cells are electrically connected to each other by the connection members 309, and the connection members 309 may be welded to the main grids of the battery cells. The main grids include a first main grid 231 electrically connected to the first electrode 214 and a second main grid 232 electrically connected to the second electrode 224.

[0110] In some embodiments, there is no space between the battery cells, i.e., the battery cells overlap each other.

[0111] In some embodiments, welding is performed between the connection member and a sub-grid in the battery cell, and the sub-grid includes a first electrode 2141 and a second electrode 2142.

[0112] In some embodiments, the encapsulating adhesive film 37 includes a first encapsulating layer and a second encapsulating layer, where the first encapsulating layer covers one of the front and back surfaces of the solar cell, and the second encapsulating layer covers the other of the front and back surfaces of the solar cell. Specifically, at least one of the first encapsulating layer and the second encapsulating layer may be an organic encapsulating adhesive film, such as a polyvinyl butyral (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.

[0113] Before lamination processing, there is a boundary between the first sealing layer and the second sealing layer, but after lamination processing, when the photovoltaic module is formed, the concepts of the first sealing layer and the second sealing layer no longer exist, and the first sealing layer and the second sealing layer are integrated to form a sealing adhesive film 37.

[0114] In some embodiments, the cover plate 38 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 38 facing the sealing adhesive film 37 may be textured to improve the utilization efficiency of incident light. The cover plate 38 includes a first cover plate and a second cover plate, where the first cover plate faces the first encapsulation layer and the second cover plate faces the second encapsulation layer, or the first cover plate faces one side of the solar cell and the second cover plate faces the other side of the solar cell.

[0115] Those skilled in the art will understand that the above embodiments are specific examples of realizing the present application, but that various changes in form and details are possible in practice without departing from the scope of the present application. Since anyone skilled in the art can make 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 scope limited by the claims.

Claims

1. The semiconductor device includes a substrate having a front surface and a back surface disposed opposite to each other, a first polysilicon doped layer doped with N-type dopant ions, a second polysilicon doped layer doped with P-type dopant ions, a first electrode, and a second electrode, the first polysilicon doped layer is located on the front surface or the back surface, and the first polysilicon doped layer has a surface facing away from the substrate with a plurality of first protrusion structures; the second polysilicon doped layer is located on the rear surface, and the first polysilicon doped layer and the second polysilicon doped layer are insulated from each other; the second polysilicon doped layer has a surface away from the substrate with a plurality of second protrusion structures, the thickness of the plurality of first protrusion structures is greater than the thickness of the plurality of second protrusion structures; and the thickness of the first polysilicon doped layer including the first protrusion structures is equal to or less than the thickness of the second polysilicon doped layer including the second protrusion structures; the first electrode is in electrical contact with the first polysilicon doped layer, and the second electrode is in electrical contact with the second polysilicon doped layer; The range of the width of the first electrode in the first direction or the width of the second electrode in the first direction is 5 μm to 50 μm. A solar cell characterized by:

2. a surface roughness of the first polysilicon doped layer including the plurality of first protrusion structures is greater than a surface roughness of the second polysilicon doped layer including the plurality of second protrusion structures; The solar cell according to claim 1 .

3. The surface roughness of the first polysilicon doped layer including the plurality of first protrusion structures is in the range of 10 nm to 30 nm. The solar cell according to claim 2 .

4. The surface roughness of the second polysilicon doped layer including the plurality of second protrusion structures ranges from 0 nm to 20 nm. The solar cell according to claim 2 .

5. the thickness range of the plurality of first protrusion structures is 30 nm or less; The solar cell according to claim 1 .

6. The thickness range of the plurality of second protrusion structures is 20 nm or less. The solar cell according to claim 1 .

7. The range of one-dimensional dimensions of the plurality of first protrusion structures is 0 μm to 500 μm. The solar cell according to claim 1 .

8. The range of one-dimensional dimensions of the plurality of second protrusion structures is 0 um to 300 um; The solar cell according to claim 1 .

9. The thickness of the second polysilicon doped layer including the plurality of second protrusion structures is in the range of 100 nm to 400 nm. The solar cell according to claim 1 .

10. The thickness of the first polysilicon doped layer including the plurality of first protrusion structures is in the range of 50 nm to 300 nm. The solar cell according to claim 1 .

11. the first polysilicon doped layer is located on the back surface, the back surface includes an N region and a P region, the first polysilicon doped layer is located in the N region, and the second polysilicon doped layer is located in the P region; The solar cell according to claim 1 .

12. At least one cell string formed by connecting a plurality of solar cells according to any one of claims 1 to 11; at least one sealing adhesive film for covering a surface of the at least one cell string; and at least one cover plate for covering a surface of the at least one sealing adhesive film remote from the at least one cell string. A photovoltaic module characterized by:

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