Solar cell and preparation method thereof

Abstract

The invention provides a solar cell and a preparation method thereof, the solar cell is formed by cutting a whole cell, and the solar cell comprises a cell body; the plurality of section cracks are arranged at intervals along a first direction, the plurality of section cracks are located in the cell body, the density of the section cracks in the first direction is 1 / 10 [mu] m-30 / 10 [mu] m, and the first direction is perpendicular to the thickness direction of the cell body. According to the invention, the problem of low assembly power caused by large recombination and poor carrier transport of a half cell in the prior art is solved.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and more particularly, to a solar cell and a method for manufacturing a solar cell. Background Art

[0002] In the currently known half-cell manufacturing technology, high-power thermal cracking lasers are mainly used for heating, and then cooling water is sprayed at the same position to provide a temperature gradient field to form thermal stress. When the generated tensile stress reaches the fracture limit of the silicon material, the silicon wafer cracks stably to achieve the purpose of cutting. The temperature difference between the upper and lower surfaces should reach the range of 150°-250°; since the (100), (110), and (111) crystal planes of the silicon material are the main fracture planes, the fracture toughness differences between the three are small. The thermal stress exceeds the corresponding fracture strength in all three crystal directions and will be unevenly released along the three crystal directions, resulting in a large density of stripe grooves at the cross-section position, and a large number of dangling bonds are exposed from the three crystal directions, greatly affecting the recombination density at this position and the subsequent passivation film formation effect. In the prior art, there are negative problems such as a large number of dangling bonds, large recombination, poor carrier transport, and affecting the passivation film effect in the cross-section stripe grooves of solar cells. Summary of the Invention

[0003] The main object of this application is to provide a solar cell and a method for manufacturing a solar cell to solve the problems of large recombination and poor carrier transport in half-cells in the prior art, which lead to low module power.

[0004] To achieve the above object, according to one aspect of this application, a solar cell is provided. The solar cell is formed by cutting a whole solar cell, and the solar cell includes: a cell body; a plurality of cross-section cracks arranged at intervals in a first direction, and the plurality of cross-section cracks are located in the cell body. In the first direction, the density of the cross-section cracks is 1 crack / 10μm to 30 cracks / 10μm, and the first direction is perpendicular to the thickness direction of the cell body.

[0005] Optionally, the width of the cross-section crack in a second direction is 0.1μm - 3μm. The second direction is perpendicular to the thickness direction of the cell body, and the second direction intersects with the first direction.

[0006] Optionally, the width of the cross-section crack in the first direction is 0μm - 1μm.

[0007] Optionally, the cell body has a cutting cross-section formed by cutting, and the cross-section crack extends from the cutting cross-section into the cell body. The solar cell further includes: a passivation film located in the cross-section crack and on the cutting cross-section outside the cross-section crack.

[0008] Optionally, the passivation film includes: a first sub-passivation film located in the cross-sectional crack; a second sub-passivation film located on the cut surface outside the cross-sectional crack, wherein the width of the second sub-passivation film in a second direction is greater than the width of the first sub-passivation film in the second direction, the second direction is perpendicular to the thickness direction of the cell body, and the second direction intersects with the first direction.

[0009] Optionally, the width of the first sub-passivation film in the second direction is 10 nm to 20 nm, and the width of the second sub-passivation film in the second direction is 40 nm to 50 nm.

[0010] Optionally, the material of the passivation film includes at least one of the following: aluminum oxide, silicon oxide, and silicon nitride.

[0011] Optionally, the spacing range between two adjacent cross-sectional cracks is 0.3 μm to 9 μm.

[0012] Optionally, the cross-sectional shape of the cross-sectional crack includes at least one of the following: linear, wavy, and serrated.

[0013] According to another aspect of the present application, there is provided a method for manufacturing any one of the solar cells, including: providing a whole piece of cell; performing laser cutting on the whole piece of cell along the thickness direction of the whole piece of cell to obtain a plurality of solar cells, wherein the solar cell includes a cell body and a plurality of cross-sectional cracks spaced along a first direction, and the plurality of cross-sectional cracks are located in the cell body. In the first direction, the setting density of the cross-sectional cracks is 1 per 10 μm to 30 per 10 μm, and the first direction is perpendicular to the thickness direction of the cell body.

[0014] Applying the technical solution of the present application, the solar cell is formed by cutting a whole piece of cell. The solar cell includes a cell body and a plurality of cross-sectional cracks spaced along a first direction. Among them, the plurality of cross-sectional cracks are located in the cell body, and the density of the cross-sectional cracks in the first direction is 1 per 10 μm to 30 per 10 μm. Compared with the problems of large recombination and poor carrier transport in half cells in the prior art, resulting in low module power, the density of the cross-sectional cracks in the present application is 1 per 10 μm to 30 per 10 μm, which can significantly reduce the number of dangling bonds. The reduction in the number of dangling bonds reduces the non-radiative recombination rate of carriers on the surface, thereby improving the conversion efficiency of the battery. In addition, the lower density of the cross-sectional stripes can make the cross-section smoother, which helps to reduce the obstacles on the carrier transport path, thereby improving the carrier transport efficiency, and further ensuring a higher module power. Description of the Drawings

[0015] The accompanying drawings forming a part of this application are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation to this application. In the drawings:

[0016] Figure 1 A top view schematic diagram of a solar cell provided according to an embodiment of this application is shown;

[0017] Figure 2 A top view schematic diagram of a specific solar cell provided according to an embodiment of this application is shown;

[0018] Figure 3 A cross-sectional structure schematic diagram of a solar cell provided according to an embodiment of this application is shown.

[0019] Among them, the above-mentioned drawings include the following reference numerals:

[0020] 10. Cell body; 11. Cross-sectional crack; 101. Cutting cross-section; 12. Passivation film; 13. Substrate; 14. Emitter; 15. Passivation layer; 16. First antireflection film; 17. Tunneling layer; 18. Doped conductive layer; 19. Second antireflection film; 20. First metal electrode; 21. Second metal electrode. Detailed implementation manners

[0021] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.

[0022] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary implementation manners according to this application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "include" and / or "comprise" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0023] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element can be directly on the other element, or there can also be an intermediate element. Moreover, in the specification and claims, when an element is described as being "connected" to another element, the element can be "directly connected" to the other element, or "connected" to the other element through a third element.

[0024] As introduced in the background art, in the prior art, the recombination of half-cell wafers is large and the carrier transport is poor, resulting in low module power. To solve the above problems, embodiments of the present application provide a solar cell wafer and a method for manufacturing a solar cell wafer.

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention.

[0026] Embodiments of the present application provide a solar cell wafer, which is formed by cutting a whole wafer, such as Figure 1 、 Figure 2 and Figure 3 shown, the above solar cell wafer includes:

[0027] Wafer body 10;

[0028] A plurality of cross-sectional cracks 11 arranged at intervals in the first direction, and the plurality of cross-sectional cracks 11 are located in the wafer body 10. In the first direction, the density of the cross-sectional cracks 11 is 1 per 10 μm to 30 per 10 μm, and the first direction is perpendicular to the thickness direction of the wafer body 10.

[0029] Through the above embodiments, the solar cell wafer is formed by cutting a whole wafer. The solar cell wafer includes a wafer body and a plurality of cross-sectional cracks arranged at intervals in the first direction. Among them, the plurality of cross-sectional cracks are located in the wafer body, and the density of the cross-sectional cracks in the first direction is 1 per 10 μm to 30 per 10 μm. Compared with the problem that the recombination of half-cell wafers in the prior art is large and the carrier transport is poor, resulting in low module power, the density of the cross-sectional cracks in the present application is 1 per 10 μm to 30 per 10 μm, which can significantly reduce the number of dangling bonds. The reduction of the number of dangling bonds reduces the non-radiative recombination rate of carriers on the surface, thereby improving the conversion efficiency of the battery. In addition, the lower density of the cross-sectional stripes can make the cross-section smoother, which helps to reduce the obstacles on the carrier transport path, thereby improving the carrier transport efficiency, and further ensuring a higher module power.

[0030] In addition, on the surface of the high-density cross-sectional cracks, the passivation film is unevenly deposited in the grooves, forming defects, affecting its compactness and coverage effect, and reducing the passivation effect. By reducing the density of the cross-sectional cracks in the present application, a smoother surface can be created, which is beneficial to the uniform growth of the subsequent passivation film and the improvement of its compactness. This not only reduces the defects in the passivation film, but also ensures the consistency of the passivation effect on the entire battery surface, improving the open-circuit voltage and fill factor of the battery.

[0031] Specifically, the reason why the reduction in the density of cross-section cracks can lead to a decrease in the number of dangling bonds is mainly related to the crystal structure of the silicon material and the crack formation mechanism. During the cutting process of the solar cell wafer, whether it is mechanical cutting or laser cutting, micro-cracks will be generated on the cross-section of the cell wafer. These cracks destroy the crystal continuity of the silicon material, resulting in the appearance of dangling bonds in the crystal structure, that is, unpaired valence electron sites. Dangling bonds are a source of carrier recombination, which will increase the surface recombination rate and reduce the cell efficiency. The reduction in the density of cross-section cracks means that the number of cross-section cracks per unit length decreases, so the number of dangling bonds caused by the cross-section cracks also decreases accordingly.

[0032] Specifically, only cracks with a width in the second direction ranging from 0.1 μm to 3 μm belong to the cross-section cracks in this application. That is, when calculating the density of cross-section cracks in the first direction, only cross-section cracks with a width in the second direction ranging from 0.1 μm to 3 μm are considered.

[0033] In some embodiments, the solar cell wafer can be any one of a PERC cell (Passivated Emitter and Rear Cell), a PERT cell (Passivated Emitter and Rear Totally diffused cell), a TOPCon cell (Tunnel Oxide Passivated Contact), a HIT / HJT cell (Heterojunction Technology), or a BC cell (Back Contact).

[0034] In some embodiments, the solar cell wafer can be a monocrystalline silicon photovoltaic cell, a polycrystalline silicon photovoltaic cell, an amorphous silicon photovoltaic cell, or a multi-component compound photovoltaic cell. The multi-component compound photovoltaic cell can specifically be a cadmium sulfide photovoltaic cell, a gallium arsenide photovoltaic cell, a copper indium selenide photovoltaic cell, or a perovskite photovoltaic cell.

[0035] Taking the TOPCon cell as an example, as Figure 3As shown, the cell body 10 in the solar cell includes a substrate 13, and further includes an emitter 14, a passivation layer 15, and a first antireflection film 16 that are sequentially stacked on one side of the substrate 13, and further includes a tunneling layer 17, a doped conductive layer 18, and a second antireflection film 19 that are sequentially stacked on the other side of the substrate 13. The cell body 10 further includes a plurality of first metal electrodes 20 spaced apart on the surface of the first antireflection film 16 away from the substrate 13, and a plurality of second metal electrodes 21 spaced apart on the surface of the second antireflection film 19 away from the substrate 13. Among them, the doping types of the emitter 14 and the doped conductive layer 18 are different. The first metal electrode is electrically connected to the emitter, and the second metal electrode is electrically connected to the doped conductive layer. The substrate is used to receive incident light and generate photo-generated carriers. The first metal electrode and the second metal electrode are used to collect photo-generated carriers. The passivation layer can prevent the surface of the emitter from being oxidized or corroded to improve the stability and lifespan of the entire cell. The tunneling layer can achieve the effect of chemical passivation. Due to the existence of interface state defects on the surface of the substrate, the tunneling layer can saturate the dangling bonds on the surface of the substrate, reduce the density of defect states on the surface of the substrate, and reduce the recombination centers on the surface of the substrate to reduce the carrier recombination rate, making the interface state density on the surface of the substrate relatively large. The increase in the interface state density will promote the recombination of photo-generated carriers, increase the fill factor, short-circuit current, and open-circuit voltage of the photovoltaic cell, so as to improve the photoelectric conversion efficiency of the photovoltaic cell; the first antireflection film and the second antireflection film can reduce the reflectivity of sunlight on the surface of the photovoltaic cell, enable more light to be absorbed and converted into electrical energy, thereby improving the light absorption efficiency of the photovoltaic cell, and the antireflection film can protect the internal structure of the cell, avoid the cell from being polluted by the environment, and improve the stability of the photovoltaic cell.

[0036] Specifically, the material of the substrate can be at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. The materials of the passivation layer can each include one or more of materials such as silicon oxide, silicon nitride, silicon oxynitride, carbon oxynitride, titanium oxide, hafnium oxide, or aluminum oxide. The passivation layer can be a single-layer structure or a stacked structure. For example, the single-layer structure can be a single-layer aluminum oxide film layer, a single-layer silicon oxide film layer, a single-layer silicon nitride film layer, or a single-layer silicon oxynitride film layer, and the stacked structure can be composed of at least two film layers of aluminum oxide film layer, silicon oxide film layer, silicon nitride film layer, or silicon oxynitride film layer stacked. The substrate can be an N-type semiconductor substrate or a P-type semiconductor substrate. The N-type semiconductor substrate is doped with an N-type doping element, and the N-type doping element can be at least one of group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type semiconductor substrate is doped with a P-type element, and the P-type doping element can be at least one of group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In). The material of the tunneling layer can include at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or magnesium fluoride.

[0037] Specifically, in the embodiments of the present application, the substrate is an N-type silicon substrate, the emitter is a P+ emitter, and the doped conductive layer is an n+poly (i.e., n-type doped polysilicon) layer.

[0038] Specifically, when the whole solar cell is cut in the present application, the cutting line needs to be set at a position where there is no metal electrode.

[0039] Specifically, as Figure 1 and Figure 2 shown, the shapes of the cracks (not labeled) at both ends of the solar cell body 10 in the first direction are irregular. The width of this part of the crack in the second direction is greater than the width of the cross-section crack 11 in the middle part of the solar cell body 10 in the first direction, and this part of the crack is discontinuous in the third direction, that is, there will be broken segments. Therefore, the cross-section cracks in the present application generally do not consider the cracks at both ends of the solar cell in the first direction. As Figure 3 shown, the third direction is parallel to the thickness direction of the solar cell body 10.

[0040] In an alternative embodiment, the width of the above cross-section crack in the second direction is 0.1μm - 3μm. The second direction is perpendicular to the thickness direction of the solar cell body, and the second direction intersects with the first direction. In this embodiment, reducing the width of the cross-section crack in the second direction (i.e., the depth of the cross-section crack) means reducing the surface area at the cross-section, thereby reducing the number of exposed dangling bonds. Dangling bonds are important sites for carrier recombination. Therefore, the reduction of the depth helps to further reduce the surface recombination rate and further improve the carrier lifetime and efficiency.

[0041] According to some exemplary embodiments of the present application, the width of the above cross-section crack in the first direction is 0μm - 1μm. In this embodiment, reducing the width of the cross-section crack in the first direction enables the subsequent solar cell to be more evenly covered by the passivation film during the passivation process, further reducing the discontinuity or defects of the passivation film in the wider trenches, thereby further enhancing the integrity of the passivation film, further improving the passivation effect, and further reducing the surface recombination rate.

[0042] According to some exemplary embodiments of the present application, as Figure 1 , Figure 2 and Figure 3 shown, the above solar cell body 10 has a cutting cross-section 101 formed by cutting, and the above cross-section crack 11 extends from the cutting cross-section 101 into the solar cell body 10, as Figure 2As shown, the above solar cell also includes: a passivation film 12, located in the above cross-section crack 11 and on the above cutting cross-section 101 outside the above cross-section crack 11. In this embodiment, the passivation film can effectively passivate the dangling bonds in the cutting cross-section and the cross-section crack, further reduce the surface recombination, further improve the carrier lifetime and the open-circuit voltage of the battery, thereby further improving the module power. In addition, the presence of the passivation film, especially covering the cross-section crack and the cutting cross-section, can effectively block the impurities in the environment from entering the interior of the solar cell, reduce the surface defects, and improve the stability of the cell.

[0043] Specifically, the cross-section crack of the present application improves the cross-section flatness, which is beneficial to the film-forming quality and flatness uniformity of the passivation film, improves the growth uniformity and denseness of the passivation film, makes the mass density of the passivation film significantly increased and the coverage more complete, reduces the uneven passivation phenomenon at the cross-section crack gully, and achieves a certain improvement in the open voltage and filling, thus improving the module power.

[0044] According to some other exemplary embodiments of the present application, the above passivation film includes: a first sub-passivation film, located in the above cross-section crack; a second sub-passivation film, located on the above cutting cross-section outside the above cross-section crack, the width of the second sub-passivation film in the second direction is greater than the width of the first sub-passivation film in the second direction, the second direction is perpendicular to the thickness direction of the battery cell body, and the second direction intersects with the first direction. In this embodiment, the first sub-passivation film in the cross-section crack is thinner, which can ensure that the dangling bonds inside the crack are passivated, and at the same time avoid forming voids or delamination inside the crack due to an overly thick passivation film, which affects the uniformity and denseness of the passivation film. The thicker second sub-passivation film can better resist the erosion of the external environment and improve the weather resistance and long-term stability of the solar cell.

[0045] In some other alternative solutions of the present application, the width of the first sub-passivation film in the second direction is 10 nm to 20 nm, and the width of the second sub-passivation film in the second direction is 40 nm to 50 nm. In this embodiment, the widths of the first sub-passivation film and the second sub-passivation film in the second direction are set within the above range to minimize the impact of the passivation film on the electrical performance of the battery while reducing the surface recombination. An overly thick passivation film will increase the resistance of the battery, while an overly thin passivation film may not effectively passivate the surface defects.

[0046] In some other alternative embodiments of the present application, the material of the passivation film includes at least one of the following: aluminum oxide, silicon oxide, and silicon nitride. In this embodiment, aluminum oxide, silicon oxide, or silicon nitride is selected as the material of the passivation film because these materials have good passivation effects and stability, can further effectively reduce surface recombination, further improve the photoelectric conversion efficiency of the solar cell, and aluminum oxide and silicon nitride also have high refractive indices, which helps to further enhance the light trapping ability.

[0047] According to some other exemplary embodiments of the present application, the spacing range between two adjacent cross-sectional cracks is 0.3 μm to 9 μm. In this embodiment, controlling the crack spacing can effectively adjust the microstructure on the surface of the cell, ensure the optimization of the carrier transmission path between the crack region and the passivation film, and help to further improve the fill factor and open-circuit voltage of the battery.

[0048] In other embodiments, the cross-sectional shape of the cross-sectional crack includes at least one of the following: linear, wavy, and serrated. In this embodiment, the shape of the cross-sectional crack is designed to be linear, wavy, or serrated in order to optimize the light scattering and absorption effects according to different illumination conditions and the material characteristics of the cell. The wavy or serrated cracks can more effectively scatter the incident light, increase the path length of the light in the cell, and thus improve the light absorption rate.

[0049] Specifically, the comparison between the cross-sectional cracks of the half-cell in the prior art and the cross-sectional cracks of the solar cell of the present application is shown in Table 1.

[0050] Table 1

[0051]

[0052] Specifically, compared with the half-cell in the prior art, the open-circuit voltage of the solar cell of the present application can be increased by 0.5 mV, the fill factor can be increased by 0.3 to 0.4, the efficiency of the solar cell can be increased by 3% to 5%, and the power of the photovoltaic module can be increased by 0.5 W to 1 W.

[0053] The embodiment of the present application also provides a method for manufacturing a solar cell, which includes the following steps:

[0054] Step S201, providing a whole cell;

[0055] Step S202, laser cut the whole piece of solar cell along the thickness direction of the whole piece of solar cell to obtain a plurality of solar cells. Among them, the solar cell includes a cell body and a plurality of cross-sectional cracks arranged at intervals in a first direction. The plurality of cross-sectional cracks are located in the cell body. In the first direction, the setting density of the cross-sectional cracks is 1 crack / 10μm to 30 cracks / 10μm, and the first direction is perpendicular to the thickness direction of the cell body.

[0056] Through the above embodiments, first, a whole piece of solar cell is provided, and then the whole piece of solar cell is laser cut along the thickness direction of the whole piece of solar cell to obtain a plurality of solar cells. Among them, the solar cell includes a cell body and a plurality of cross-sectional cracks arranged at intervals in a first direction. Among them, the plurality of cross-sectional cracks are located in the cell body. In the first direction, the setting density of the cross-sectional cracks is 1 crack / 10μm to 30 cracks / 10μm. Compared with the problems of large recombination of half cells and poor carrier transport in the prior art resulting in low module power, the density of the cross-sectional cracks in this application is 1 crack / 10μm to 30 cracks / 10μm, which can significantly reduce the number of dangling bonds. The reduction in the number of dangling bonds reduces the non-radiative recombination rate of carriers on the surface, thereby improving the conversion efficiency of the battery. In addition, the lower cross-sectional stripe density can make the cross-section smoother, which helps to reduce the obstacles on the carrier transport path, thereby improving the carrier transport efficiency, and further ensuring a higher module power.

[0057] Specifically, taking the whole piece of solar cell as a Topcon cell as an example, providing the whole piece of solar cell includes: providing an N-type silicon substrate; forming a P+ emitter on the upper surface of the silicon substrate; forming a tunneling layer on the lower surface of the silicon substrate; forming a passivation layer on the upper surface of the P+ emitter; forming an n+poly layer on the lower surface of the tunneling layer; forming a first antireflection film on the upper surface of the passivation layer; forming a second antireflection film on the lower surface of the n+poly layer; forming a plurality of first metal electrodes arranged at intervals on the upper surface of the first antireflection film; forming a plurality of second metal electrodes arranged at intervals on the lower surface of the second antireflection film. The first metal electrode is electrically connected to the P+ emitter, and the second metal electrode is electrically connected to the n+poly layer.

[0058] Specifically, in the present application, the specific process of cutting a whole solar cell is as follows: First, laser grooving is performed at both ends of the first cutting line of the whole solar cell, then the position where the first cutting line is located is preheated, and then the position where the first cutting line is located is scanned by a thermal cracking laser, and finally the position where the second cutting line is located is cooled, so that the cooled whole solar cell cracks to obtain the solar cell of the present application (i.e., the segmented cell). Among them, the first cutting line is located on the front side of the whole solar cell, the second cutting line is located on the back side of the whole solar cell, and the projection of the first cutting line on the back side overlaps with the second cutting line. In the existing solar cell cutting process, generally, grooving is first performed, and then the cutting position of the solar cell is directly scanned by a thermal cracking laser after grooving, and after scanning, a coolant water mist is directly sprayed along the same trajectory at the cutting position to complete the cutting. Compared with the half solar cell obtained by using the existing solar cell cutting process, the open circuit voltage of the solar cell of the present application can be increased by 0.5 mV, the fill factor can be increased by 0.3 - 0.4, the efficiency of the solar cell can be increased by 3% - 5%, and the module power can be increased by 0.5 W - 1 W.

[0059] In an alternative embodiment, after obtaining a plurality of solar cells, the method for manufacturing a solar cell further includes: forming a passivation film in the above-mentioned cross-sectional cracks and on the above-mentioned cutting cross-section outside the above-mentioned cross-sectional cracks.

[0060] In other embodiments, forming a passivation film in the above-mentioned cross-sectional cracks and on the above-mentioned cutting cross-section outside the above-mentioned cross-sectional cracks includes: forming a first sub-passivation film in the above-mentioned cross-sectional cracks; forming a second sub-passivation film on the above-mentioned cutting cross-section outside the above-mentioned cross-sectional cracks, the width of the second sub-passivation film in the second direction is greater than the width of the first sub-passivation film in the second direction, the second direction is perpendicular to the thickness direction of the solar cell body, and the second direction intersects with the first direction.

[0061] From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:

[0062] In the solar cell of the present application, the solar cell is formed by cutting the whole cell, and the solar cell includes a cell body and a plurality of cross-section cracks arranged at intervals in a first direction. Among them, the plurality of cross-section cracks are located in the cell body, and the density of the cross-section cracks in the first direction is 1 crack / 10μm to 30 cracks / 10μm. Compared with the problems of large recombination and poor carrier transport in half cells in the prior art, resulting in low module power, the density of the cross-section cracks in the present application is 1 crack / 10μm to 30 cracks / 10μm, which can significantly reduce the number of dangling bonds. The reduction in the number of dangling bonds reduces the non-radiative recombination rate of carriers on the surface, thereby improving the conversion efficiency of the battery. In addition, the lower density of the cross-section stripes can make the cross-section smoother, which helps to reduce the obstacles on the carrier transport path, thereby improving the carrier transport efficiency, and further ensuring a high module power.

[0063] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A solar cell, characterized in that, The solar cell is formed by cutting a whole piece of cell, and the solar cell includes: A cell body; A plurality of cross-sectional cracks arranged at intervals in a first direction, the plurality of cross-sectional cracks are located in the cell body, and in the first direction, the density of the cross-sectional cracks is 1 crack / 10μm to 30 cracks / 10μm, and the first direction is perpendicular to the thickness direction of the cell body.

2. The solar cell according to claim 1, wherein, The width of the cross-sectional crack in a second direction is 0.1μm - 3μm, the second direction is perpendicular to the thickness direction of the cell body, and the second direction intersects with the first direction.

3. The solar cell according to claim 1, characterized in that, The width of the cross-sectional crack in the first direction is 0μm - 1μm.

4. The solar cell according to any one of claims 1 to 3, characterized in that, The cell body has a cutting cross-section formed by cutting, and the cross-sectional crack extends from the cutting cross-section into the cell body. The solar cell further includes: a passivation film located in the cross-sectional crack and on the cutting cross-section outside the cross-sectional crack.

5. The solar cell according to claim 4, characterized in that, The passivation film includes: A first sub-passivation film located in the cross-sectional crack; A second sub-passivation film located on the cutting cross-section outside the cross-sectional crack, the width of the second sub-passivation film in the second direction is greater than the width of the first sub-passivation film in the second direction, the second direction is perpendicular to the thickness direction of the cell body, and the second direction intersects with the first direction.

6. The solar cell according to claim 5, wherein, The width of the first sub-passivation film in the second direction is 10nm - 20nm, and the width of the second sub-passivation film in the second direction is 40nm - 50nm.

7. The solar cell according to claim 4, characterized in that, The material of the passivation film includes at least one of the following: aluminum oxide, silicon oxide, and silicon nitride.

8. The solar cell according to claim 1, wherein The spacing range between two adjacent cross-sectional cracks is 0.3μm - 9μm.

9. The solar cell according to claim 1, characterized in that, The cross-sectional shape of the cross-sectional crack includes at least one of the following: linear, wavy, and serrated.

10. The preparation method of the solar cell according to any one of claims 1 to 9, characterized in that, Including: Providing a whole piece of cell; Laser cutting the whole piece of cell along the thickness direction of the whole piece of cell to obtain a plurality of solar cells, wherein the solar cell includes a cell body and a plurality of cross-sectional cracks arranged at intervals in a first direction, the plurality of cross-sectional cracks are located in the cell body, and in the first direction, the setting density of the cross-sectional cracks is 1 crack / 10μm to 30 cracks / 10μm, and the first direction is perpendicular to the thickness direction of the cell body.

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