Solar cell, manufacturing method and photovoltaic module

Abstract

The invention relates to a solar cell, a manufacturing method and a photovoltaic module. The solar cell comprises a silicon substrate, a first doped semiconductor layer and a second doped semiconductor layer, the first doped semiconductor layers and the second doped semiconductor layers are alternately arranged on the first surface of the silicon substrate; the electrical properties of the first doped semiconductor layer and the second doped semiconductor layer are different; a plurality of bulge structures which are arranged at intervals along the first direction are arranged on one surface, deviating from the silicon substrate, of the first doped semiconductor layer; the length extension direction of each convex structure is different from the first direction; the first direction is the extension direction of the collector electrode of the solar cell, and the electrode can achieve the same purpose by using fewer materials, so that the electrode can be manufactured to be narrower, the electrode material is saved, and the cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of solar photovoltaic technology, and in particular to a solar cell, a manufacturing method, and a photovoltaic module. Background Technology

[0002] Solar cells are devices that directly convert light energy into electrical energy.

[0003] The relevant technology can first prepare a patterned passivation layer and a doped polycrystalline silicon layer on the back of the solar cell, and then deposit another passivation layer and a doped amorphous silicon layer on the entire back of the solar cell. Then, the local doped amorphous silicon above the doped polycrystalline silicon is removed to expose the doped polycrystalline silicon. Finally, a transparent conductive layer and electrodes are used to conduct electricity of different electrical properties to realize solar cell power generation.

[0004] Currently, electrodes need to be placed in the area above the exposed doped polycrystalline silicon. In order to ensure the adhesion of the electrodes, the electrodes need to be made wider, which leads to higher costs. Summary of the Invention

[0005] This invention provides a solar cell, a manufacturing method, and a photovoltaic module, aiming to partially or completely solve the technical problem that existing technologies require wider electrode fabrication, which leads to higher costs.

[0006] To solve the above problems, the present invention is implemented as follows: In a first aspect, embodiments of the present invention provide a solar cell, comprising: In a first aspect, embodiments of the present invention provide a solar cell, the solar cell comprising a silicon substrate, a first doped semiconductor layer, and a second doped semiconductor layer; the silicon substrate has a first surface and a second surface, the first surface and the second surface being disposed opposite to each other; the first doped semiconductor layer and the second doped semiconductor layer are alternately disposed on the first surface of the silicon substrate; the first doped semiconductor layer and the second doped semiconductor layer have different electrical properties; On the side of the first doped semiconductor layer facing away from the silicon substrate, there are a plurality of protrusions spaced apart along a first direction; the length extension direction of each protrusion is different from the first direction; the first direction is the extension direction of the current collector electrode of the solar cell.

[0007] Secondly, embodiments of the present invention provide a method for manufacturing a solar cell, the method comprising: A silicon substrate is provided; the silicon substrate has a first surface and a second surface, the first surface and the second surface being disposed opposite to each other; Alternating first-doped semiconductor layers and second-doped semiconductor layers are formed on a first surface of the silicon substrate; the first-doped semiconductor layer and the second-doped semiconductor layer have different electrical properties. On the side of the first doped semiconductor layer facing away from the silicon substrate, a plurality of protrusion structures are formed at intervals along a first direction; the length extension direction of each protrusion structure is different from the first direction; the first direction is the extension direction of the current collector electrode of the solar cell.

[0008] Thirdly, embodiments of the present invention provide a photovoltaic module, the photovoltaic module including a cover plate, a back plate, and a solar cell disposed between the cover plate and the back plate; the solar cell includes the solar cell as described above.

[0009] In this embodiment of the invention, the side of the first doped semiconductor layer facing away from the silicon substrate has a plurality of protrusions spaced apart along a first direction. This allows the plurality of protrusions on the first doped semiconductor layer to form an uneven surface structure, increasing the contact area, surface roughness, and specific surface area per unit area. This increases the adhesion when other components are arranged, thereby improving the pull-out force of the electrode during fabrication. In particular, under the condition of satisfying the same pull-out force, the increased surface contact area of ​​the plurality of protrusions spaced apart along the first direction allows the electrode to achieve the same purpose with less material, thus enabling the electrode to be made narrower, saving electrode material, and reducing costs.

[0010] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0011] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 A schematic diagram of the cross-sectional structure of a solar cell according to an embodiment of the present invention is shown; Figure 2 A top view of a solar cell according to an embodiment of the present invention is shown; Figure 3 A schematic diagram of a laser spot distribution in an embodiment of the present invention is shown; Figure 4 A top view of a protruding structure according to an embodiment of the present invention is shown; Figure 5 A side view of a protrusion structure according to an embodiment of the present invention is shown; Figure 6A surface SEM image of an overlapping region of laser spots in an embodiment of the present invention is shown; Figure 7 A cross-sectional SEM image of the overlapping region of a laser spot is shown in an embodiment of the present invention; Figure 8 A cross-sectional SEM image of another laser spot overlap region in an embodiment of the present invention is shown; Figure 9 A surface SEM image of another laser spot overlap region in an embodiment of the present invention is shown; Figure 10 A top view of another protruding structure in an embodiment of the present invention is shown; Figure 11 A flowchart illustrating the steps of a method for manufacturing a solar cell according to an embodiment of the present invention is shown.

[0012] Explanation of reference numerals in the attached figures: 10-First doped semiconductor layer; 20-Second doped semiconductor layer; 30-Silicon substrate; 11-Protrusion structure; 12-Parts; 40-Opening region; 41-Vacuum structure; 111-First protrusion; 113-First recess; 112-Second protrusion; 50-Transparent conductive layer; 60-Tunneling layer; 21-Intrinsic amorphous silicon layer; 100-Electrode; 80-Passivation layer; 90-Insulating layer; 114-Third protrusion; 115-Fourth protrusion; 116-Fifth protrusion; 117-Sixth protrusion; 118-Second recess; 119-Third recess; X-First direction; Y-Second direction. Detailed Implementation

[0013] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0014] Reference Figure 1 The diagram shows a cross-sectional structural schematic of a solar cell provided in an embodiment of the present invention. The solar cell includes a silicon substrate 30, a first doped semiconductor layer 10, and a second doped semiconductor layer 20. The silicon substrate 30 has a first surface and a second surface, with the first surface and the second surface disposed opposite to each other. The first doped semiconductor layer 10 and the second doped semiconductor layer 20 are alternately disposed on the first surface of the silicon substrate 30. Further reference... Figure 2On the side of the first doped semiconductor layer 10 facing away from the silicon substrate 30, there are a plurality of protrusion structures 11 spaced apart along a first direction; the length extension direction of each protrusion structure 11 is different from the first direction X; the first direction X is the extension direction of the current collector electrode of the solar cell.

[0015] Specifically, in the solar cell, one of the first surface and the second surface is the front side of the silicon substrate 30, and the other of the first surface and the second surface is the back side of the silicon substrate 30. One of the first doped semiconductor layer 10 and the second doped semiconductor layer 20 is an N-type doped semiconductor layer, and the other of the first doped semiconductor layer 10 and the second doped semiconductor layer 20 is a P-type doped semiconductor layer. In some embodiments, an example is given where the first doped semiconductor layer 10 is an N-type doped polycrystalline silicon layer and the second doped semiconductor layer 20 is a P-type doped amorphous silicon layer.

[0016] In this embodiment of the invention, reference is made to Figure 2 Because the first doped semiconductor layer 10 and the second doped semiconductor layer 20 have different electrical properties, alternating N-regions and P-regions can be formed on the surface of the solar cell. The N-region is the electron transport region of the solar cell, and the P-region is the hole transport region. The current collector electrode is typically a fine grid electrode, used to extract charge carriers from the solar cell. The bus electrode is typically a main grid electrode, used to combine the charge carriers transported by multiple current collector electrodes together.

[0017] It should be noted that the first doped semiconductor layer 10 and the second doped semiconductor layer 20 can be connected to each other (they can partially overlap in the thickness direction and be adjacent to each other in the extension direction). The first doped semiconductor layer 10 and the second doped semiconductor layer 20 can also have an isolation region (they can not be adjacent to each other in the extension direction and can be separated by an isolation structure). This embodiment of the present invention does not limit this.

[0018] Reference Figure 2 In this embodiment of the invention, the solar cell can be a back contact cell (BC). The side of the first doped semiconductor layer 10 facing away from the silicon substrate 30 has a plurality of protrusion structures 11 spaced apart along a first direction X. The formation process of the protrusion structures 11 will be described below: A partial second doped semiconductor layer 20 is stacked on the first doped semiconductor layer 10 of the solar cell. After laser processing, the partial second doped semiconductor layer 20 stacked on the first doped semiconductor layer 10 can form an opening region 40 for setting electrodes on the first doped semiconductor layer 10. The opening region 40 extends along the first direction X. During the laser formation of the opening region 40, the laser spot can be rectangular or square (or other shapes), and multiple laser spots are arranged along the first direction X, with possible overlap between adjacent laser spots.

[0019] Because the energy of a laser spot is stronger near the center and weaker near the edges, this invention utilizes this characteristic by specially designing a local overlap between laser spots during the manufacturing process, forming overlapping areas.

[0020] Because laser spots have high energy near the center and low energy near the edges, the overlapping areas between adjacent laser spots include edge overlap areas and center overlap areas, which have different morphological characteristics. A protruding structure according to embodiments of the present invention can be formed at the edge overlap area.

[0021] like Figure 3 The diagram illustrates the distribution of square laser spots 1 to 4. The laser spots extend along the first direction X to form an opening region. Due to the uneven energy distribution within the laser spots, partial overlap between adjacent laser spots is required for the opening region to form. For example, laser spot 2 has an edge overlap region 2-1, a central region 2-3, and an edge overlap region 2-2. Edge overlap regions 2-1 and 2-2 have the same characteristics. Because the laser energy in edge overlap regions 2-1 and 2-2 is weaker, while the laser energy in the central region 2-3 is stronger, a portion of the second doped semiconductor layer 20 remains at these two regions. This remaining portion of the second doped semiconductor layer 20 forms the protrusion structure 11 of this embodiment of the invention, and multiple protrusion structures 11 are spaced apart along the first direction X.

[0022] In this embodiment of the invention, the side of the first doped semiconductor layer 10 facing away from the silicon substrate 30 has a plurality of protrusions 11 spaced apart along a first direction X. This allows the plurality of protrusions 11 on the first doped semiconductor layer 10 to form an uneven surface structure, increasing the contact area, surface roughness, and specific surface area per unit area of ​​the protrusions 11. Compared to a smooth surface structure, the aforementioned characteristics of the protrusions 11 per unit area increase the adhesion when arranging other components. This improves the pull-out force of the electrode (especially the current collector electrode) during fabrication. In particular, under the condition of satisfying the same pull-out force, the increased surface contact area of ​​the plurality of protrusions 11 spaced apart along the first direction X allows the current collector electrode to achieve the same purpose with less material. This allows the current collector electrode to be made narrower, saving electrode material and reducing costs. In addition, the narrower current collector electrode can also reduce the light-shielding effect of the current collector electrode, thereby improving battery performance. Furthermore, the increased surface roughness of the protrusions 11 also improves the adhesion of the subsequently applied transparent conductive layer. The unit area can be any of the area sizes such as 5nm×5nm, 10nm×10nm, etc.

[0023] The side of the first doped semiconductor layer facing away from the silicon substrate has a relatively flat open-film area without protrusions, which can increase the film quality of subsequent layers, improve passivation effect, and enhance solar cell efficiency.

[0024] Furthermore, for back-contact batteries, both the current collector (fine grid) and the busbar (main grid) are located on the back of the battery. The surface of the fine grid is coated with insulating adhesive, and a non-standard main grid is positioned above the insulating adhesive. The insulating adhesive serves to isolate the main grid from the non-standard fine grid. Under the same contact conditions, the raised structure per unit area can reduce the linewidth of the fabricated fine grid. With the same amount of insulating adhesive, due to the narrower linewidth of the fine grid, the insulating adhesive in the area where the raised structure is located will provide more complete coverage and better encapsulation compared to the insulating adhesive in the planar area, thereby preventing the current collector and the non-standard busbar from overlapping and reducing the risk of leakage. In addition, for OBB batteries without a main grid, a solder strip is provided above the insulating adhesive, and the solution of this embodiment of the invention has the same effect in this scenario.

[0025] Furthermore, for example, when using screen-printed electrode paste, the solution of this embodiment can also avoid the problem of some large, flaky particles adhering to the current collector electrode position due to uneven Ag / Cu particles (silver-coated copper paste, i.e., copper as the main body with silver powder attached around the main body) during the electrode printing process. With the same amount of insulating adhesive, Ag / Cu particles in the narrower linewidth region are less likely to penetrate beyond the insulating adhesive film layer, thus reducing the risk of overlap between the main grid and the irregular fine grid, and decreasing leakage current.

[0026] Furthermore, under the same contact conditions, the raised structure can narrow the line width of the fine grid, thereby matching the narrowed printing screen. During printing alignment and adjustment, the width window of the fine grid alignment within the laser film opening area becomes larger, and the fine grid offset is easier to adjust. In addition, when a dense fine grid (multiple fine grids) is set, the area where the raised structure is located can narrow the fine grid line width per unit area compared to the planar area. Narrowing the fine grid line width can reduce the amount of insulating adhesive used and its expandability, allowing the insulation adhesive to maintain a better shape and not easily collapse, reducing the risk of overlapping of dissimilar main fine grids.

[0027] Furthermore, the laser spot moves along the first direction X. The surface morphology of the laser-irradiated area is divided into a planar area and a region with a raised structure. The presence of the raised structure increases the area on the back of the solar cell that reflects light, thereby increasing the light propagation path and improving the light trapping effect of the solar cell.

[0028] Optional, refer to Figures 1 to 10 The protrusion structure 11 includes a portion of the second doped semiconductor layer 20.

[0029] In this embodiment of the invention, the protrusion structure 11 can be formed by the remaining portion of the second doped semiconductor layer 20 after laser irradiation of a portion of the second doped semiconductor layer 20 stacked on the first doped semiconductor layer 10. The remaining portion of the second doped semiconductor layer 20 forms the protrusion structure 11, which increases the adhesion of the collector electrode arranged on the first doped semiconductor layer 10, allowing the collector electrode to achieve the same purpose with less material. This makes the collector electrode narrower, saves electrode material, and reduces costs.

[0030] Optional, refer to Figure 2 On the side of the first doped semiconductor layer 10 facing away from the silicon substrate 30, the area without the protrusion structure 11 is designated as the first region, and the area where the protrusion structure 11 is located is designated as the second region. The surface roughness of the solar cell in the first region is less than that in the second region. The surface of the solar cell refers to the surface excluding the metal electrode material, such as the surface after removing residual metal electrode paste, the surface after removing electroplated metal electrodes, or the surface after removing physically deposited metal electrodes.

[0031] This results in a larger surface roughness of the solar cell in the second region where the protrusion structure 11 is located, which increases the adhesion when other components are arranged on the first doped semiconductor layer 10. This increases the pull-out force of the current collector electrode during fabrication. In particular, under the condition of meeting the same pull-out force, the current collector electrode can achieve the same purpose with less material, thereby making the current collector electrode narrower, saving electrode material and reducing costs.

[0032] Furthermore, the reflectivity of the solar cell in the first region is greater than that in the second region. This results in a lower reflectivity of the solar cell in the second region where the protrusion structure 11 is located, improving the light-trapping effect of the solar cell and thus enhancing its performance.

[0033] Optional, refer to Figure 2 An opening region 40 is provided on the side of the first doped semiconductor layer 10 that is away from the silicon substrate 30, and the protrusion structure 11 is located in the opening region 40.

[0034] In this embodiment of the invention, a portion of a second doped semiconductor layer 20 is stacked on the first doped semiconductor layer 10 of the solar cell. After the portion of the second doped semiconductor layer 20 stacked on the first doped semiconductor layer 10 is thinned by laser irradiation, an opening region 40 for setting electrodes can be formed on the first doped semiconductor layer 10. The protrusion structure 11 in this embodiment of the invention is located in the opening region 40. When the electrode is subsequently fabricated in the opening region 40, the surface roughness of the solar cell in the region is relatively large due to the protrusion structure 11, which can improve the pull-out force of the current collector electrode, so that the current collector electrode can achieve the same purpose with less material. This allows the current collector electrode to be made narrower, saving electrode material and reducing costs.

[0035] In the process of preparing the second doped semiconductor layer, a portion of the second doped semiconductor layer is stacked on the first doped semiconductor layer, and a partial opening is made in the second doped semiconductor layer on the first doped semiconductor layer. This avoids damage to the stack and the second doped semiconductor layer. Then, a transparent conductive layer with better conductivity is prepared on the first doped semiconductor layer and the second doped semiconductor layer. Finally, an electrode is prepared on the transparent conductive layer.

[0036] Optional, refer to Figure 2 On the side of the first doped semiconductor layer 10 facing away from the silicon substrate 30, the length extension direction of the protrusion structure 11 is a second direction Y perpendicular to the first direction X. Along the second direction Y, the length of the protrusion structure 11 is 20 μm to 400 μm, preferably 40 μm to 200 μm; more preferably, the length of the protrusion structure 11 is 40 μm to 100 μm. In practical applications, the length of the protrusion structure 11 can be selected according to actual needs. For example, the length of the protrusion structure 11 can be any value among 20 μm, 40 μm, 60 μm, 80 μm, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm, 200 μm, 220 μm, 240 μm, 260 μm, 280 μm, 300 μm, 320 μm, 340 μm, 360 μm, 380 μm, and 400 μm.

[0037] In this embodiment of the invention, the extension direction of the current collector electrode of the solar cell is the first direction X, and the length extension direction of the protrusion structure 11 is the second direction Y, which is perpendicular to the first direction X. This allows the multiple protrusion structures 11 arranged at intervals in the first direction X to form an uneven surface structure, thereby improving the adhesion and pull-out force of the current collector electrode and increasing the surface contact area of ​​the current collector electrode. This allows the current collector electrode to achieve the same purpose with less material, thereby making the current collector electrode narrower, saving electrode material and reducing costs.

[0038] Optional, refer to Figure 2 An opening region 40 is formed on the side of the first doped semiconductor layer 10 facing away from the silicon substrate 30, and a protrusion structure 11 is located in the opening region 40. The length of the protrusion structure 11 is less than or equal to the width of the opening region 40 in the second direction Y. If the length of the protrusion structure 11 is greater than the width of the opening region 40 in the second direction Y, it will damage the passivation of the stacked structure on the first doped semiconductor layer, affecting the power generation performance of the solar cell. Therefore, the length of the protrusion structure 11 is usually set to be less than or equal to the width of the opening region 40 in the second direction Y, which is more conducive to the passivation effect and improves the power generation performance of the solar cell.

[0039] Optional, refer to Figure 2 Along the first direction X, the width of the protruding structure 11 is 5μm to 200μm, preferably 10μm to 100μm; more preferably, the width of the protruding structure 11 is 20μm to 50μm. In practical applications, the width of the protruding structure 11 can be selected according to actual needs. For example, the width of the protruding structure 11 can be any value among 5μm, 20μm, 40μm, 60μm, 80μm, 100μm, 120μm, 140μm, 160μm, 180μm, and 200μm.

[0040] Optionally, the height of the protrusion structure along the thickness direction of the solar cell is 3nm to 100nm; preferably, the height of the protrusion structure is 6nm to 50nm; more preferably, the height of the protrusion structure is 12nm to 25nm. In practical applications, the height of the protrusion structure can be selected according to actual needs, for example, any value among 3μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, and 100μm.

[0041] Optionally, the spacing between adjacent protrusions is 2μm to 500μm; preferably, the spacing is 50μm to 300μm; more preferably, the spacing is 100μm to 200μm. In practical applications, the spacing between adjacent protrusions can be selected according to actual needs, for example, any value can be taken from 2μm, 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 120μm, 150μm, 160μm, 170μm, 180μm, 200μm, 230μm, 260μm, 290μm, 300μm, 400μm, and 500μm.

[0042] Optional, refer to Figure 4 and Figure 5 , Figure 4 The top view of the protruding structure 11 is shown. Figure 5 The side view of the protrusion structure 11 is shown. The protrusion structure 11 includes: a first protrusion 111, a first recess 113, and a second protrusion 112; the first protrusion 111, the first recess 113, and the second protrusion 112 all extend along a second direction Y perpendicular to the first direction X; the first recess 113 is located between the first protrusion 111 and the second protrusion 112.

[0043] In this embodiment of the invention, the protruding structure 11 may be composed of a first protruding portion 111, a first recessed portion 113, and a second protruding portion 112. The first recessed portion 113 is located between the first protruding portion 111 and the second protruding portion 112, forming a structure with a cross-section resembling a valley sandwiched between two mountain peaks. The formation process of the specific structural form of the protruding structure 11 will be described below: Because laser spots have higher energy near the center and lower energy near the edges, the overlapping areas between adjacent laser spots include edge overlap areas and center overlap areas, and these two types of overlap areas have different characteristic morphologies. A protruding structure according to an embodiment of the present invention can be formed at the location of the edge overlap area. Referring to... Figure 3 For the laser spot 2, there are an edge overlap region 2-1, a central region 2-3, and an edge overlap region 2-2. The edge overlap regions 2-1 and 2-2 have the same characteristics. Since the laser energy in the edge overlap regions 2-1 and 2-2 is relatively weak, while the laser energy in the central region 2-3 is relatively strong, a portion of the second doped semiconductor layer 20 remains at the locations of these two regions. This remaining portion of the second doped semiconductor layer 20 forms the protrusion structure 11 of this embodiment of the invention.

[0044] Furthermore, the interiors of edge overlap region 2-1 and edge overlap region 2-2 can each be divided into different areas, as shown in the reference. Figure 6 Taking the edge overlap region 2-1 as an example, it is divided into region 2-1-1, region 2-1-2, and region 2-1-3. Region 2-1-1 is the overlap region between the upper edge of laser spot 2 and the central region of laser spot 1; region 2-1-2 is the overlap region between the central region of laser spot 2 and the central region of laser spot 1; and region 2-1-3 is the overlap region between the central region of laser spot 2 and the edge region of laser spot 1. Regions 2-1-1 and 2-1-3 have the same characteristics. Since regions 2-1-1 and 2-1-3 are formed by the superposition of the light spot edge and the light spot center, the laser energy in regions 2-1-1 and 2-1-3 is relatively weak. Region 2-1-2 is formed by the superposition of the light spot center and the light spot center, so the laser energy in region 2-1-2 is relatively strong. Therefore, a set of continuous regions 2-1-1, 2-1-2 and 2-1-3 can form the above-mentioned protruding structure 11. Region 2-1-1 forms the first protrusion 111, region 2-1-2 forms the first depression 113, and region 2-1-3 forms the second protrusion 112.

[0045] Further reference Figure 7 It shows a scanning electron microscope (SEM) image of an opening region, which specifically shows... Figure 6 A schematic diagram of the protruding structure 11 formed in the central region 2-1-1.

[0046] Optional, refer to Figure 7 The protruding structure 11 also has particles 12, the size of which is 50nm-200nm, preferably 75nm-150nm; more preferably, the size of which is 90nm-100nm. In practical applications, the size of the particles 12 can be selected according to actual needs, for example, the size of the particles 12 can be any value among 75nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, and 150nm. The size includes, but is not limited to: length, width, height, diameter, radius, and diagonal length.

[0047] The protruding structure 11 also has particles 12, which can further increase the contact surface area of ​​the electrodes arranged in the opening area, further improve the adhesion of the arranged electrodes, and make the current collecting electrodes narrower, saving electrode materials and reducing costs. In addition, the particles 12 on the protruding structure 11 can improve the light trapping effect of the solar cell and improve the optical performance of the solar cell.

[0048] Further reference Figure 8It shows a scanning electron microscope image of another opening region, which specifically shows Figure 6 A schematic diagram of the morphology of region 2-1-2. There is basically no residue of the second doped semiconductor layer in region 2-1-2, only some molten silicon particles 13.

[0049] Optional, refer to Figure 2 An opening region 40 is formed on the side of the first doped semiconductor layer 10 facing away from the silicon substrate, and a protrusion structure 11 is located in the opening region 40. The area in the opening region 40 without the protrusion structure 11 has a hole structure with a length of 10 nm to 200 nm. The length direction of the hole structure is a first direction on the first surface.

[0050] In practical applications, the length of the hole structure can be selected according to actual needs. For example, the length of the hole structure can be any value among 10nm, 20nm, 40nm, 60nm, 80nm, 100nm, 120nm, 140nm, 160nm, 180nm, and 200nm.

[0051] Among them, reference Figure 9 The image shows a scanning electron microscope image of a hole structure 41, which can improve the light trapping effect of solar cells and enhance their optical performance.

[0052] Optionally, the first doped semiconductor layer includes a doped polycrystalline silicon layer having an amorphous silicon region; the amorphous silicon region includes: a third region overlapping with the protrusion structure and a fourth region overlapping with the region without the protrusion structure; the thickness of the amorphous silicon in the third region is 1 nm to 50 nm.

[0053] In practical applications, the thickness of the amorphous silicon in the third region can be selected according to actual needs, for example, any value among 1nm, 3nm, 5nm, 10nm, 15nm, 20nm, 25nm, 30nm, 40nm, and 50nm.

[0054] In addition, the area of ​​the third region is smaller than that of the fourth region.

[0055] In an embodiment of the invention, for example, at least a portion of the transparent conductive layer of the solar cell can be disposed on the amorphous silicon region of the doped polycrystalline silicon layer of the first doped semiconductor layer 10 and in contact with the amorphous silicon region. Since the work function difference between the amorphous silicon region and the transparent conductive layer is smaller than the work function difference between the doped polycrystalline silicon layer and the transparent conductive layer, i.e., the contact barrier between the amorphous silicon region and the transparent conductive layer is smaller than the contact barrier between the doped polycrystalline silicon layer and the transparent conductive layer, the contact resistance between the amorphous silicon region and the transparent conductive layer is smaller than the contact resistance between the doped polycrystalline silicon layer and the transparent conductive layer. This allows the amorphous silicon region to achieve more reasonable bandgap matching, reducing contact resistance and enabling the solar cell to effectively convert sunlight into electrical energy, thereby improving the photoelectric conversion efficiency of the solar cell.

[0056] Optionally, the thickness of the amorphous silicon in the third region is less than the thickness of the amorphous silicon in the fourth region.

[0057] In the third region, the area of ​​amorphous silicon is smaller than that of amorphous silicon in the fourth region. Therefore, by setting a thicker layer of amorphous silicon in the larger area, more transparent conductive layers can come into contact with the thicker amorphous silicon, thereby achieving better and more reasonable bandgap matching and reducing contact resistance.

[0058] Optionally, on the silicon substrate, the surface of the region where the first doped semiconductor layer is located is a polished surface.

[0059] On the silicon substrate, the surface of the region where the first doped semiconductor layer is located is polished, which makes the contact interface of the film layer flat, which is beneficial to the film formation quality on the surface and achieves better passivation performance.

[0060] Optional, refer to Figure 1 The solar cell further includes: a transparent conductive layer 50, a tunneling layer 60, and an intrinsic amorphous silicon layer 21; a first doped semiconductor layer 10 including a doped polycrystalline silicon layer; a second doped semiconductor layer 20 including a doped crystalline silicon layer; a tunneling layer 60 located between the doped polycrystalline silicon layer and the silicon substrate 30; the intrinsic amorphous silicon layer 21 in contact with the side of the doped crystalline silicon layer facing the silicon substrate 30; a portion of the second doped semiconductor layer 20 is stacked on a portion of the first doped semiconductor layer 10; and the transparent conductive layer 50 is disposed on at least a portion of the first doped semiconductor layer 10 and a portion of the second doped semiconductor layer 20.

[0061] In this embodiment of the invention, the first doped semiconductor layer 10 and the second doped semiconductor layer 20 have different electrical properties. In one embodiment, the first doped semiconductor layer 10 includes a doped polycrystalline silicon layer, and the second doped semiconductor layer 20 includes a doped crystalline silicon layer. The first doped semiconductor layer 10 is used to form an N-region doped layer to provide electron transport for the solar cell; the second doped semiconductor layer 20 is used to form a P-region doped layer to provide hole transport for the solar cell.

[0062] The doped crystalline silicon layer can be any one of amorphous silicon, nanocrystalline silicon, or microcrystalline silicon. The tunneling layer 60 serves as a passivation layer, with a thickness of 0.5 nm to 5 nm, preferably 1.2 nm to 2 nm. The tunneling layer 60 is made of any one or a combination of multiple layers of silicon oxide, aluminum oxide, silicon nitride, silicon carbide, and magnesium oxide. Additionally, the solar cell may include an electrode 100, a passivation layer 80 (such as an aluminum oxide layer), and an antireflection layer 90 (such as a silicon nitride layer). The electrode 100 is disposed on the transparent conductive layer 50, the passivation layer 80 is disposed on the second surface of the silicon substrate 30, and the antireflection layer 90 is disposed on the passivation layer 80.

[0063] The transparent conductive layer 50 is used to collect charge carriers. The electrodes 100 and the transparent conductive layer 50 disposed below them together form a system for collecting and transporting charge carriers.

[0064] It should be noted that the shape of the protrusion structure 11 in the embodiments of the present invention is not limited to... Figure 2 , Figure 4 , Figure 5 The structural form shown, for example, refers to Figure 10 The protruding structure 11 may include a third protrusion 114, a fourth protrusion 115, a fifth protrusion 116, a sixth protrusion 117, a second recess 118, and a third recess 119; wherein the third protrusion 114, the second recess 118, and the fourth protrusion 115 extend along the second direction Y, the fifth protrusion 116, the third recess 119, and the sixth protrusion 117 extend along the first direction X, the second recess 118 is located between the third protrusion 114 and the fourth protrusion 115, and the third recess 119 is located between the fifth protrusion 116 and the sixth protrusion 117.

[0065] Reference Figure 11 The present invention also provides a method for manufacturing a solar cell, the method comprising the following steps: S101. A silicon substrate is provided; the silicon substrate has a first surface and a second surface, the first surface and the second surface being disposed opposite to each other.

[0066] In this step, the provided silicon substrate can be polished and cleaned to remove the cutting damage layer on the first and second surfaces of the silicon substrate, and the polishing morphology of the first and second surfaces can be controlled by adjusting the temperature, time and concentration of the polishing solution.

[0067] S102, An alternating first doped semiconductor layer and a second doped semiconductor layer are formed on the first surface of the silicon substrate, wherein the first doped semiconductor layer and the second doped semiconductor layer have different electrical properties.

[0068] In this step, one of the first surface and the second surface is the front side of the silicon substrate 30, and the other of the first surface and the second surface is the back side of the silicon substrate 30. One of the first doped semiconductor layer 10 and the second doped semiconductor layer 20 is an N-type doped semiconductor layer, and the other of the first doped semiconductor layer 10 and the second doped semiconductor layer 20 is a P-type doped semiconductor layer. In some embodiments, an example is given where the first doped semiconductor layer 10 is an N-type doped polycrystalline silicon layer and the second doped semiconductor layer 20 is a P-type doped amorphous silicon layer.

[0069] In this embodiment of the invention, since the first doped semiconductor layer 10 and the second doped semiconductor layer 20 have different electrical properties, alternating N-regions (A1) and P-regions (A2) can be formed on the surface of the solar cell. The N-region is the electron transport region of the solar cell, and the P-region is the hole transport region of the solar cell.

[0070] It should be noted that the first doped semiconductor layer 10 and the second doped semiconductor layer 20 can be interconnected, and there can also be an isolation region between the first doped semiconductor layer 10 and the second doped semiconductor layer 20. This embodiment of the invention does not limit this.

[0071] S103. On the side of the first doped semiconductor layer facing away from the silicon substrate, a plurality of protrusion structures are formed at intervals along a first direction; the length extension direction of each protrusion structure is different from the first direction; the first direction is the extension direction of the current collector electrode of the solar cell.

[0072] In this embodiment of the invention, reference is made to Figure 1 and Figure 2 The side of the first doped semiconductor layer 10 facing away from the silicon substrate 30 has a plurality of protrusions 11 spaced apart along the first direction X. This allows the plurality of protrusions 11 on the first doped semiconductor layer 10 to form an uneven surface structure, increasing the contact area, surface roughness, and specific surface area per unit area of ​​the protrusions 11. Compared with a smooth surface structure, the aforementioned characteristics of the protrusions 11 per unit area increase the adhesion when arranging other components. This improves the pull-out force of the electrode (especially the current collector electrode) during fabrication. In particular, under the condition of satisfying the same pull-out force, the increased surface contact area of ​​the plurality of protrusions 11 spaced apart along the first direction X allows the current collector electrode to achieve the same purpose with less material. This allows the current collector electrode to be made narrower, significantly saving electrode material and reducing costs. In addition, the narrower current collector electrode can also reduce the light-shielding effect of the current collector electrode, thereby improving the performance of the solar cell.

[0073] This invention also provides a photovoltaic module, which includes a cover plate, a back sheet, and a solar cell disposed between the cover plate and the back sheet; the solar cell includes the solar cell described above.

[0074] The embodiments of the present invention do not specifically limit whether the photovoltaic module includes other structures. For example, the photovoltaic module may also include: a first encapsulating film disposed between the cover plate and the solar cell, and a second encapsulating film disposed between the back sheet and the solar cell.

[0075] In summary, in this embodiment of the invention, the side of the first doped semiconductor layer facing away from the silicon substrate has a plurality of protrusions spaced apart along a first direction. This allows the plurality of protrusions on the first doped semiconductor layer to form an uneven surface structure, increasing the contact area, surface roughness, and specific surface area per unit area. This increases the adhesion when other components are arranged, thereby improving the pull-out force of the electrode during printing. In particular, under the condition of satisfying the same pull-out force, the increased surface contact area of ​​the plurality of protrusions spaced apart along the first direction allows the electrode to achieve the same purpose with less paste, thereby enabling the electrode to be printed narrower, significantly saving electrode paste and reducing costs.

[0076] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0077] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. For embodiments of devices, electronic devices, computer-readable storage media, and computer program products containing instructions, the descriptions are relatively simple because they are basically similar to the method embodiments; relevant parts can be referred to the descriptions of the method embodiments.

[0078] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A solar cell, characterized in that, The solar cell includes a silicon substrate, a first doped semiconductor layer, and a second doped semiconductor layer; the silicon substrate has a first surface and a second surface, the first surface and the second surface being disposed opposite to each other; the first doped semiconductor layer and the second doped semiconductor layer are alternately disposed on the first surface of the silicon substrate; The first doped semiconductor layer and the second doped semiconductor layer have different electrical properties; On the side of the first doped semiconductor layer facing away from the silicon substrate, there are a plurality of protrusion structures spaced apart along a first direction; The length extension direction of each of the protrusions is different from the first direction; The first direction is the extending direction of the current collecting electrode of the solar cell.

2. The solar cell according to claim 1, characterized in that, On the side of the first doped semiconductor layer facing away from the silicon substrate, the area without the protrusion structure is a first region, and the area where the protrusion structure is located is a second region. The surface roughness of the solar cell in the first region is less than that of the solar cell in the second region.

3. The solar cell according to claim 1, characterized in that, An opening region is provided on the side of the first doped semiconductor layer facing away from the silicon substrate, and the protrusion structure is located in the opening region.

4. The solar cell according to claim 1, characterized in that, On the side of the first doped semiconductor layer facing away from the silicon substrate, the length extension direction of the protrusion structure is a second direction perpendicular to the first direction; along the second direction, the length of the protrusion structure is 20μm~400μm, preferably, the length of the protrusion structure is 40μm-200μm; more preferably, the length of the protrusion structure is 40μm-100μm.

5. The solar cell according to claim 4, characterized in that, An opening region is provided on the side of the first doped semiconductor layer facing away from the silicon substrate, and the protrusion structure is located in the opening region; The length of the protrusion is less than or equal to the width of the opening region in the second direction.

6. The solar cell according to claim 1, characterized in that, Along the first direction, the width of the protrusion structure is 5μm to 200μm, preferably 10μm to 100μm; more preferably, the width of the protrusion structure is 20μm to 50μm.

7. The solar cell according to claim 1, characterized in that, Along the thickness direction of the solar cell, the height of the protrusion structure is 3nm~100nm, preferably 6nm~50nm; more preferably, the height of the protrusion structure is 12nm~25nm.

8. The solar cell according to claim 1, characterized in that, The spacing between adjacent protrusions is 2μm to 500μm, preferably 50μm to 300μm; more preferably 100μm to 200μm.

9. The solar cell according to any one of claims 1-8, characterized in that, The protruding structure includes: a first protruding portion, a first recessed portion, and a second protruding portion; the first protruding portion, the first recessed portion, and the second protruding portion all extend along a second direction perpendicular to the first direction; The first recess is located between the first protrusion and the second protrusion.

10. The solar cell according to claim 1, characterized in that, The protrusion structure includes a portion of the second doped semiconductor layer.

11. The solar cell according to claim 1, characterized in that, The protruding structure also has particles with a size of 50nm-200nm, preferably 75nm-150nm; more preferably, the size of the particles is 90nm-100nm.

12. The solar cell according to claim 1, characterized in that, An opening region is provided on the side of the first doped semiconductor layer facing away from the silicon substrate, and the protrusion structure is located in the opening region; The area in the opening region that does not have the protrusion structure has the hole structure, and the length of the hole structure is 10nm~200nm.

13. The solar cell according to claim 1, characterized in that, The first doped semiconductor layer includes a doped polycrystalline silicon layer, the doped polycrystalline silicon layer having an amorphous silicon region; the amorphous silicon region includes: a third region overlapping with the protrusion structure, and a fourth region overlapping with a region without the protrusion structure; The thickness of the amorphous silicon in the third region is 1 nm to 50 nm.

14. The solar cell according to claim 13, characterized in that, The thickness of the amorphous silicon in the third region is less than the thickness of the amorphous silicon in the fourth region.

15. The solar cell according to claim 1, characterized in that, In the silicon substrate, the surface of the region where the first doped semiconductor layer is located is a polished surface.

16. The solar cell according to claim 1, characterized in that, The solar cell further includes: a transparent conductive layer, a tunneling layer, and an intrinsic amorphous silicon layer; The first doped semiconductor layer includes a doped polycrystalline silicon layer; the second doped semiconductor layer includes a doped crystalline silicon layer; the tunneling layer is located between the doped polycrystalline silicon layer and the silicon substrate; the intrinsic amorphous silicon layer is in contact with the side of the doped crystalline silicon layer facing the silicon substrate; A portion of the first doped semiconductor layer is stacked with a portion of the second doped semiconductor layer; the transparent conductive layer is disposed on at least a portion of the first doped semiconductor layer and a portion of the second doped semiconductor layer.

17. A method for manufacturing a solar cell, characterized in that: A silicon substrate is provided; the silicon substrate has a first surface and a second surface, the first surface and the second surface being disposed opposite to each other; Alternating first-doped semiconductor layers and second-doped semiconductor layers are formed on the first surface of the silicon substrate; The first doped semiconductor layer and the second doped semiconductor layer have different electrical properties; On the side of the first doped semiconductor layer facing away from the silicon substrate, a plurality of protrusion structures are formed at intervals along a first direction; The length extension direction of each of the protrusions is different from the first direction; The first direction is the extending direction of the current collecting electrode of the solar cell.

18. A photovoltaic module, characterized in that, The photovoltaic module includes a cover plate, a back sheet, and a battery string disposed between the cover plate and the back sheet, the battery string including a plurality of solar cells connected in series by interconnecting elements; the solar cells include the solar cells as described in any one of claims 1 to 16.

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