Solar cell and method for manufacturing solar cell

Abstract

The invention relates to the field of solar cells, and provides a solar cell and a preparation method of the solar cell. The solar cell comprises a substrate, the substrate is provided with a first surface and a second surface which are opposite, and the second surface is provided with a groove; the first doped conductive layer is positioned on the first surface or the second surface on at least one side of the groove; the second doped conductive layer is at least partially located in the groove, and the doping type of the first doped conductive layer is different from that of the second doped conductive layer; the first electrode is positioned on one side, far away from the substrate, of the first doped conductive layer and is in contact with the first doped conductive layer; and the second electrode is at least partially positioned on one side, far away from the substrate, of the second doped conductive layer in the groove. The solar cell solves the technical problem of how to improve the efficiency of the solar cell in the prior art.

Description

Technical Field

[0001] The present invention relates to the field of solar cells, and more particularly, to a solar cell and a method for manufacturing the same. Background Art

[0002] In the prior art, to improve the efficiency of solar cells, it is necessary to reduce the resistance and at the same time increase the fill factor. However, the current improvement methods are not highly efficient.

[0003] Therefore, there is an urgent need for a solar cell and a method for manufacturing the same that can solve the problem of how to improve the efficiency of solar cells.

[0004] The above information disclosed in the background art is only used to enhance the understanding of the background art of the technology described herein. Therefore, the background art may contain certain information that is not prior art known to those skilled in the art in their own country. Summary of the Invention

[0005] The main object of the present invention is to provide a solar cell and a method for manufacturing the same, so as to solve the problem of how to improve the efficiency of solar cells in the prior art.

[0006] To achieve the above object, according to one aspect of the present invention, there is provided a solar cell, including: a substrate having opposite first and second surfaces, the second surface having a groove; a first doped conductive layer located on the first surface or on at least one side of the groove on the second surface; a second doped conductive layer at least partially located in the groove, wherein the doping type of the first doped conductive layer is different from the doping type of the second doped conductive layer; a first electrode located on the side of the first doped conductive layer away from the substrate and in contact with the first doped conductive layer; and a second electrode at least partially located on the side of the second doped conductive layer in the groove away from the substrate.

[0007] Further, the portion of the first doped conductive layer is located on a partial area of the first surface, and the second doped conductive layer is also located on the second surface on both sides of the groove.

[0008] Further, there are a plurality of the grooves, and there is a gap between any two of the grooves.

[0009] Further, the first doped conductive layer is located on the second surface on both sides of the groove and has a gap from the second doped conductive layer.

[0010] Further, the shape of the cross-section of the groove in a predetermined direction is one of a circle, an ellipse, and a polygon, and the predetermined direction is perpendicular to the direction of the thickness of the substrate.

[0011] Further, the maximum distance between the groove and the second surface is 3 - 20 μm, and the width of the groove is 30 - 40 μm.

[0012] Further, at least a part of one of the first surface and the second surface has a matte surface structure, the matte surface structure includes a plurality of pyramid structures, and the maximum diameter of the orthographic projection of the pyramid structure on the substrate is 5 - 30 μm.

[0013] To achieve the above object, according to one aspect of the present invention, there is provided a method for manufacturing a solar cell, including: providing a preliminary substrate having opposite first and second surfaces; removing a part of the preliminary substrate on the side of the second surface to obtain a substrate having a groove; forming a first doped conductive layer in a part of the groove on the first surface or the second surface; forming a second doped conductive layer in at least a part of the groove, wherein the doping type of the first doped conductive layer is different from the doping type of the second doped conductive layer; forming a first electrode on the side of the first doped conductive layer away from the substrate, and one end of the first electrode is in contact with the first doped conductive layer; forming a second electrode in at least a part of the second groove.

[0014] Further, removing a part of the preliminary substrate on the side of the second surface to obtain a substrate having a groove includes: disposing a mask layer on the second surface; using the mask layer as a mask and removing a part of the preliminary substrate by a laser process. According to another aspect of the present invention, there is provided a photovoltaic module, including: a battery string formed by connecting any one of the above-mentioned solar cells, wherein the solar cell is a passivated contact cell or a back contact cell; an encapsulation layer for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulation layer on the side away from the battery string.

[0015] Applying the technical solution of the present invention, the above-mentioned solar cell includes: a substrate having a groove on the second surface, a first doped conductive layer, a second doped conductive layer, a first electrode, and a second electrode. The first doped conductive layer is located on the first surface or on the second surface at least on one side of the groove; the second doped conductive layer is at least partially located in the groove; the first electrode is located on the side of the first doped conductive layer away from the substrate and is in contact with the first doped conductive layer; the second electrode is at least partially located on the side of the second doped conductive layer in the groove away from the substrate. The beneficial effects of the present invention are:

[0016] Since the substrate has grooves and the second doped conductive layer is located in the grooves, compared with the prior art solution of arranging the second doped layer on one side surface of the substrate, the distance of the second doped conductive layer relative to the second surface can be increased; in addition, since the second electrode is also located in the grooves, compared with the prior art solution where the substrate does not have grooves, the contact area between the electrode and the emitter can be increased. Since the series resistance is inversely proportional to the contact area between the electrode and the emitter, the above arrangement can reduce the series resistance of the solar cell, improve the output power and output voltage, thereby enhancing the fill factor of the solar cell and achieving the technical effect of improving the efficiency of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0018] Figure 1 shows a schematic structural diagram of a solar cell provided according to an embodiment of the present invention;

[0019] Figure 2 shows a schematic structural diagram of another solar cell provided according to an embodiment of the present invention;

[0020] Figure 3 shows a schematic structural diagram of grooves with different shapes provided according to an embodiment of the present invention;

[0021] Figure 4 shows a schematic structural diagram of a solar cell provided according to the prior art;

[0022] Figure 5 shows a schematic flow diagram of a preparation method of a solar cell provided according to an embodiment of the present invention;

[0023] Figure 6 shows a schematic structural diagram of preparing a substrate to obtain a substrate with grooves;

[0024] Figure 7 shows forming a first doped conductive layer on the basis of Figure 6 ;

[0025] Figure 8 shows forming a second doped conductive layer on the basis of Figure 7 ;

[0026] Figure 9 shows forming a first electrode on the basis of Figure 8 ;

[0027] Figure 10shows the structural schematic diagram of forming a second electrode on the basis of Figure 9 ;

[0028] Figure 11 shows the structural schematic diagram of providing a preliminary substrate according to an embodiment of the present application and forming a mask layer on the preliminary substrate;

[0029] Figure 12 shows the structural schematic diagram of a photovoltaic module provided according to an embodiment of the present invention.

[0030] Among them, the above-mentioned drawings include the following reference numerals:

[0031] 10. Substrate; 11. Groove; 12. First doped conductive layer; 13. Second doped conductive layer; 14. First passivation layer; 15. First antireflection layer; 16. Tunneling dielectric layer; 17. Second antireflection layer; 18. Third antireflection layer; 19. Third passivation layer; 20. Fourth passivation layer; 21. Fourth antireflection layer; 22. Mask layer; 30. First electrode; 31. Second electrode; 40. Solar cell; 402. Conductive strip; 41. Encapsulation layer; 42. Cover plate. Detailed implementation manners

[0032] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0033] The following further describes the present application in detail with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present application.

[0034] As introduced in the background art, the efficiency of solar cells in the prior art is low. To solve the above technical problems, the present application proposes a solar cell.

[0035] The structural schematic diagram of the solar cell according to an embodiment of the present application. As Figure 1 and Figure 2 shown, it includes:

[0036] Substrate 10, the above-mentioned substrate 10 has opposite first and second surfaces, and the second surface has a groove 11.

[0037] Specifically, the substrate 10 is used to receive incident light and generate photo-generated carriers. The above-mentioned substrate 10 can be either an N-type substrate or a P-type substrate. In the N-type substrate, any one of pentavalent elements such as phosphorus (P), bismuth (Bi), arsenic (As), or antimony (Sb) can be doped. In the P-type substrate, any one of trivalent elements such as boron (B), aluminum (Al), indium (In), or gallium (Ga) can be doped. The groove 11 can be formed into a grooved or patterned structure by methods such as laser or etching. It should be noted that in subsequent steps, a first electrode 30 will be formed on one of the first surface or the second surface of the substrate 10, and a second electrode 31 will be formed on the second surface of the substrate 10.

[0038] The first doped conductive layer 12 is located on the above-mentioned first surface or on the above-mentioned second surface at least on one side of the above-mentioned groove 11;

[0039] Specifically, the first doped conductive layer 12 can be formed by doping P-type doping ions or N-type doping ions on the first surface or the second surface of the substrate 10, and can be made by methods such as diffusion method, plasma enhanced chemical vapor deposition, physical vapor deposition, etc., so as to form a P-N junction with the substrate 10. The N-type doping ions can be pentavalent elements such as phosphorus (P), bismuth (Bi), arsenic (As), or antimony (Sb), and the P-type doping ions can be trivalent elements such as boron (B), aluminum (Al), indium (In), or gallium (Ga). The thickness of the first doped conductive layer 12 can be 100-300 nm. The first doped conductive layer 12 can be provided on either the first surface or the second surface, or can be provided on both the first surface and the second surface at the same time. The second doped conductive layer 13 is at least partially located in the above-mentioned groove 11, wherein the doping type of the above-mentioned first doped conductive layer 12 is different from the doping type of the above-mentioned second doped conductive layer 13.

[0040] The second doped conductive layer 13 is at least partially located in the above-mentioned groove 11, wherein the doping type of the above-mentioned first doped conductive layer 12 is different from the doping type of the above-mentioned second doped conductive layer 13;

[0041] Specifically, the second doped conductive layer 13 can be formed by doping P-type or N-type doping ions on the second surface of the substrate 10 through methods such as diffusion method, plasma enhanced chemical vapor deposition, physical vapor deposition, etc., so as to form a P-N junction with the substrate 10. The N-type doping ions can be pentavalent elements such as phosphorus (P), bismuth (Bi), arsenic (As), or antimony (Sb), and the P-type doping ions can be trivalent elements such as boron (B), aluminum (Al), indium (In), or gallium (Ga). The thickness of the second doped conductive layer is 100 - 300 nm. The preparation method of the second doped conductive layer 13 can be the same as or different from that of the first doped conductive layer 12 described above. The thickness of the second doped conductive layer 13 can be the same as or different from that of the first doped conductive layer 12 described above. The second doped conductive layer 13 can be provided only in the groove 11 or can be provided both inside and outside the groove 11 at the same time.

[0042] The first electrode 30 is located on the side of the first doped conductive layer 12 away from the substrate 10 and is in contact with the first doped conductive layer 12.

[0043] Specifically, the material of the first electrode 30 can include one or more of aluminum, silver, gold, nickel, molybdenum, or copper. The first electrode 30 is located on the side of the first doped conductive layer 12 away from the substrate 10 and is in contact with the first doped conductive layer 12. The first electrode 30 can be formed by depositing metal paste through screen printing or electroplating processes after forming an electrode contact area on the substrate 10 by methods such as laser and chemical etching, and finally made by laser sintering.

[0044] The second electrode 31 is at least partially located on the side of the second doped conductive layer 13 in the groove 11 away from the substrate 10.

[0045] Specifically, the material of the second electrode 31 can include one or more of aluminum, silver, gold, nickel, molybdenum, or copper. The second electrode 31 can be formed by depositing metal paste through screen printing or electroplating processes after forming an electrode contact area on the substrate 10 by methods such as laser and chemical etching, and finally made by laser sintering. The second electrode 31 can have the same or different material and preparation method as the first electrode 30. The second electrode 31 can be entirely located inside the groove 11 or can be provided both inside and outside the groove 11 at the same time.

[0046] The solar cell of the present invention includes: a substrate having grooves on a second surface, a first doped conductive layer, a second doped conductive layer, a first electrode, and a second electrode. The first doped conductive layer is located on the first surface or on the second surface at least on one side of the grooves; the second doped conductive layer is at least partially located in the grooves; the first electrode is located on a side of the first doped conductive layer away from the substrate and is in contact with the first doped conductive layer; the second electrode is at least partially located on a side of the second doped conductive layer in the grooves away from the substrate. Since the substrate has grooves and the second doped conductive layer is located in the grooves, compared with the prior art solution of disposing the second doped layer on one side surface of the substrate, the distance of the second doped conductive layer relative to the second surface can be increased; in addition, since the second electrode is also located in the grooves, compared with the prior art solution where the substrate does not have grooves, the contact area between the electrode and the emitter can be increased. Since the series resistance is inversely proportional to the contact area between the electrode and the emitter, the above settings can reduce the series resistance of the solar cell, improve the output power and output voltage, thereby increasing the fill factor of the solar cell and achieving the technical effect of improving the efficiency of the solar cell.

[0047] In some specific embodiments of the present application, as Figure 1 shown, the portion of the first doped conductive layer 12 is located on a partial area of the first surface, and the second doped conductive layer 13 is also located on the second surface on both sides of the groove 11. The settings of the first doped conductive layer 12 and the second doped conductive layer 13 can effectively form charge carriers, improve the carrier transport efficiency, reduce surface recombination and enhance the passivation effect, thereby strengthening the conductivity of the battery, reducing the resistance and further increasing the fill factor, while maintaining the incident absorption of photons, so as to achieve further improvement of the battery efficiency.

[0048] Specifically, the solar cell can be a tunnel oxide passivated contact (TOPCon cell for short). Both the first surface and the second surface of the substrate 10 can be used to receive incident light. The first doped conductive layer 12 formed by diffusion, plasma enhanced chemical vapor deposition, physical vapor deposition or other methods is located on a partial area of the first surface of the substrate 10. The second doped conductive layer 13 formed by diffusion, plasma enhanced chemical vapor deposition, physical vapor deposition or other methods is located on the second surface on both sides of the groove 11. A first passivation layer 14 can also be provided on the first surface of the substrate 10. The first passivation layer 14 can be prepared by plasma enhanced chemical vapor deposition, physical vapor deposition or other methods and can be one or more of materials such as silicon oxide, silicon nitride, silicon oxynitride, carbon oxynitride, titanium oxide, hafnium oxide or aluminum oxide. The first passivation layer 14 reduces the recombination of electrons and holes by covering the defects and dangling bonds on the cell surface, thereby increasing the open circuit voltage of the cell and further improving the photoelectric conversion efficiency. A first antireflection layer 15 can be provided on the side of the first passivation layer 14 away from the substrate 10. The first antireflection layer 15 can effectively reduce the reflectivity of the cell surface, thereby increasing the light transmittance and enhancing the light absorption rate of the cell. It is usually composed of one or more of silicon oxide and silicon nitride. A first tunneling dielectric layer 16 can be provided between the second doped conductive layer 13 and the substrate 10. The tunneling dielectric layer 16 is usually composed of at least one of silicon oxide, aluminum oxide, hafnium oxide and high oxide and is formed by plasma enhanced chemical vapor deposition, physical vapor deposition or other methods. The first tunneling dielectric layer 16 can improve the carrier transport efficiency, optimize the internal electric field distribution of the cell, improve the electrical performance of the cell and further improve the photoelectric conversion efficiency. A second antireflection layer 17 can be provided between the second doped conductive layer 13 and the second electrode 31. The second antireflection layer 17 can effectively reduce the reflectivity of the cell surface, thereby increasing the light transmittance and enhancing the light absorption rate of the cell. It is usually composed of silicon oxide or silicon nitride. The material of the second antireflection layer 17 can be the same as or different from the material of the first antireflection layer 15.

[0049] In some specific embodiments of the present application, as Figure 1 shown, there are multiple grooves 11, and there is a gap between any two of the grooves 11. By providing multiple grooves 11 with gaps, the contact area between the second electrode 31 and the second doped conductive layer 13 can be increased, so that the resistance of the cell is smaller and the fill factor is higher, and further the photoelectric conversion efficiency of the cell is improved.

[0050] Specifically, more than two grooves 11 can be formed by methods such as laser and etching. At the same time, there is a certain distance interval between any two grooves 11, and the distances between each interval can be the same or different. Those skilled in the art can set intervals with the same distance and intervals with different distances according to the actual situation.

[0051] In some specific embodiments of the present application, as Figure 2 shown, the above-mentioned first doped conductive layer 12 is located on the above-mentioned second surfaces on both sides of the above-mentioned groove 11 and has an interval from the above-mentioned second doped conductive layer 13. The setting of the above-mentioned first doped conductive layer 12 can arrange both the first electrode and the second electrode on the second surface, so that there is no metal gate line blocking on the first surface, reducing the shading loss, improving the utilization rate of incident light, reducing the photoelectric loss, and further improving the photoelectric conversion efficiency of the solar cell.

[0052] Specifically, the solar cell can be a back contact cell (BC cell). The first doped conductive layer 12 is disposed on the second surfaces on both sides of the groove 11 by means of diffusion, plasma enhanced chemical vapor deposition, physical vapor deposition, etc. Therefore, both the first doped conductive layer 12 and the second doped conductive layer 13 are disposed on the second surface. The first doped conductive layer 12 and the second doped conductive layer 13 do not contact each other and there is a gap therebetween. A third passivation layer 19 can be provided on the first surface of the substrate 10. The third passivation layer 19 can be prepared by methods such as plasma enhanced chemical vapor deposition, physical vapor deposition, etc., and can be one or more of materials such as silicon oxide, silicon nitride, silicon oxynitride, carbon oxynitride, titanium oxide, hafnium oxide, or aluminum oxide. The third passivation layer 19 reduces the recombination of electrons and holes by covering the defects and dangling bonds on the cell surface, thereby increasing the open circuit voltage of the cell and further improving the photoelectric conversion efficiency. The material of the third passivation layer 19 can be the same as or different from the material of the first passivation layer 14. A third antireflection layer 18 can be provided on the side of the third passivation layer 19 away from the substrate 10. The third antireflection layer 18 can effectively reduce the reflectivity of the cell surface, thereby increasing the light transmittance and enhancing the light absorption rate of the cell. It is usually composed of one or more of silicon oxide and silicon nitride. The third antireflection layer 18 can be the same as or different from the material of the first antireflection layer. A fourth passivation layer 20 can be provided on the side of the third passivation layer 19 away from the substrate 10. The fourth passivation layer 20 can be prepared by methods such as plasma enhanced chemical vapor deposition, physical vapor deposition, etc., and can be one or more of materials such as silicon oxide, silicon nitride, silicon oxynitride, carbon oxynitride, titanium oxide, hafnium oxide, or aluminum oxide. The material of the fourth passivation layer 20 can be the same as or different from that of any one of the first passivation layer and the third passivation layer 19. A fourth antireflection layer 21 is provided on the side of the fourth passivation layer 20 away from the substrate 10. The fourth antireflection layer 21 can be composed of one or more of silicon oxide and silicon nitride. The fourth antireflection layer 21 can be the same as or different from that of any one of the third antireflection layer 18 and the first antireflection layer.

[0053] The groove in the present application can be a regular shape or an irregular shape, for example: rectangle, circle, semi - circle, trapezoid, and triangle. In some specific embodiments of the present application, as Figure 3 shown, the shape of the cross - section of the groove 11 in a predetermined direction is one of a circle, an ellipse, and a polygon. The predetermined direction is perpendicular to the direction of the thickness of the substrate 10. Different cross - sectional shapes of the groove 11 can increase the contact area, reduce the resistance, optimize the carrier transport path, increase the fill factor, and further improve the photoelectric conversion efficiency.

[0054] Specifically, the shape of the cross-section of the groove 11 in the direction perpendicular to the thickness of the above-mentioned substrate 10 can be one or more of any regular or irregular figures such as a circle, a triangle, a hexagon, and a rectangle. By setting light spots with different morphologies and then adjusting parameters such as the laser wavelength, pulse width, and path, precise laser patterning is performed to form grooves 11 of different shapes.

[0055] In some specific embodiments of the present application, as Figure 1 and Figure 2 shown, the maximum distance between the above-mentioned groove 11 and the above-mentioned second surface is 3-20 μm, and the width of the above-mentioned groove 11 is 30-40 μm. The depth and width of the above-mentioned groove 11 should not be too small to avoid the second doped conductive layer 13 and the second electrode being unable to be stably arranged in the groove, resulting in a decrease in the conductivity and transmission rate of the battery. The depth and width of the above-mentioned groove 11 should not be too large to avoid damaging the substrate 10, resulting in increased recombination and a decrease in the open-circuit voltage. Therefore, the setting of the depth and width of the above-mentioned groove 11 can ensure that the second doped conductive layer 13 and the second electrode 31 can be stably arranged in the groove 11 and form a stable contact, while also reducing damage to the substrate 10, thereby reducing the contact resistance, increasing the fill factor, and further improving the photoelectric conversion efficiency.

[0056] Specifically, the maximum distance between the above-mentioned groove 11 and the above-mentioned second surface can be any value within the above range, specifically 3 μm, 6 μm, 9 μm, 12 μm, 15 μm, 18 μm, and 20 μm. The width of the groove 11 can be any value within the above range, specifically 30 μm, 32 μm, 34 μm, 36 μm, 38 μm, and 40 μm. During the preparation process of the solar cell, the maximum distance between the above-mentioned groove and the second surface and the width of the groove can be measured by instruments such as an optical microscope, a scanning electron microscope (abbreviated as SEM), an atomic force microscope (abbreviated as AFM), a metallurgical microscope, a laser confocal microscope, and an optical profiler. In actual preparation, a suitable measurement method can be selected according to factors such as the measurement accuracy requirements, the characteristics of the solar cell, and the production efficiency. In some specific embodiments of the present application, as Figure 1 and Figure 2As shown, at least a part of one of the first surface and the second surface has a matte structure. The matte structure includes a plurality of pyramid structures. The maximum diameter of the orthographic projection of the pyramid structures on the substrate 10 is 5-30 μm. Therefore, the setting of the pyramid structures and the maximum diameter of the orthographic projection can make the distribution of the pyramid matte structure more uniform and the coverage rate larger, effectively reflecting the incident light multiple times to reduce the light reflectivity of the substrate 10, enhancing the light trapping effect, improving the light absorption rate, and further improving the photoelectric conversion efficiency of the solar cell.

[0057] Specifically, the first surface and the second surface can be textured by alkali. By adjusting parameters such as the ratio, temperature, and time of the alkali solution in the texturing process, a pyramid matte structure can be formed. Among them, the alkali solution can be KOH, NaOH, NH4OH, etc. The maximum diameter of the orthographic projection of the pyramid structures on the substrate 10 can be 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, and 30 μm. In the manufacturing process of the solar cell, the size of the pyramid matte structure can be detected in the following ways, for example: optical profiler detection, laser confocal microscope detection, and scanning electron microscope detection. Taking SEM as an example, the specific steps and methods for measuring the size of the pyramid structures using SEM are as follows: surface treatment of the solar cell sample, detecting the secondary electron signal to form an image, which can clearly show the microscopic structure of the sample surface; adjusting parameters such as the acceleration voltage, beam current intensity, and working distance according to the characteristics of the sample to obtain the best imaging effect; at the same time, selecting an appropriate magnification to clearly observe the pyramid structures. Generally, a magnification between 1000 times and 5000 times can better show the details of the pyramid. In practical applications, surface images and cross-sectional images of the pyramid structures can be taken. The surface image is used to measure the base width of the pyramid, and the cross-sectional image is used to measure the height of the pyramid. By using image analysis software to analyze the above images, the size of the pyramid structures can be obtained. In some specific embodiments of the present application, as Figure 1 and Figure 2 shown, the area of the orthographic projection of the first doped conductive layer 12 on the substrate 10 is the first area, and the area of the orthographic projection of the second doped conductive layer 13 on the substrate 10 is the second area. The ratio range of the sum of the first area and the second area to the area of the substrate 10 is 20-40%. The setting of the first area and the second area will affect the transport efficiency of electrons and holes. The size of the area will affect the transport rate and recombination strength of carriers. Therefore, the setting of the ratio of the sum of the first area and the second area to the area of the substrate 10 can balance the light absorption and the carrier transport efficiency, and at the same time can reduce the increase in parasitic absorption caused by too large a doping area, reduce the recombination loss, and further improve the photoelectric conversion efficiency.

[0058] Specifically, the ratio range of the sum of the first area and the second area to the area of the base can be selected from any value within the above range, and specifically can be 20-25%, 25-30%, 30-35%, and 35-40%. In practical applications, the measurement of the first area and the second area can be carried out in the same manner as the measurement of the groove width and depth above.

[0059] The above technical solution of the present application can be used for the tunneling resistance or any other thin-layer resistance test of full back electrode contact cells such as Zero Busbar (abbreviated as 0BB) or MULTI-BUSBAR (abbreviated as MBB), Interdigitated Back Contact (abbreviated as IBC), All Back Contact solar cells (abbreviated as ABC), Hybrid Passivated Back Contact (abbreviated as HPBC), Passivated Emitter and Rear Cell (abbreviated as PERC), Tnuuel Oxide Passivated contact (abbreviated as TOPcon), TOPcon-IBC cells, Heterojunction with Intrinsic Thin-layer (HJT), perovskite tandem cells, flexible cells and other photovoltaic cells.

[0060] Next, the manufacturing method of the solar cell of the present application will be specifically described in conjunction with specific Examples 1-11 and comparative examples.

[0061] Example 1

[0062] This example provides a solar cell, including: a base, the base having opposite first and second surfaces, the second surface having a groove, the shape of the cross-section of the groove in a predetermined direction being circular, the predetermined direction being perpendicular to the direction of the thickness of the base;

[0063] A first doped conductive layer located on the first surface or on the second surface at least on one side of the groove;

[0064] A second doped conductive layer at least partially located in the groove, wherein the doping type of the first doped conductive layer is different from the doping type of the second doped conductive layer;

[0065] The first electrode is located on the side of the first doped conductive layer away from the substrate and in contact with the first doped conductive layer;

[0066] The second electrode is at least partially located on the side of the second doped conductive layer in the groove away from the substrate.

[0067] Example 2

[0068] This example provides a solar cell. The only difference between this solar cell and Example 1 is that the shape of the cross-section of the groove along a predetermined direction is a regular hexagon.

[0069] Example 3

[0070] This example provides a solar cell. The only difference between this solar cell and Example 1 is that the shape of the cross-section of the groove along a predetermined direction is an equilateral triangle.

[0071] Example 4

[0072] This example provides a solar cell, including: a substrate having opposite first and second surfaces. The second surface has a groove. The maximum distance between the groove and the second surface is 3 μm, and the width of the groove is 30 μm;

[0073] A first doped conductive layer is located on the first surface or on the second surface at least on one side of the groove;

[0074] A second doped conductive layer is at least partially located in the groove, wherein the doping type of the first doped conductive layer is different from the doping type of the second doped conductive layer;

[0075] The first electrode is located on the side of the first doped conductive layer away from the substrate and in contact with the first doped conductive layer;

[0076] The second electrode is at least partially located on the side of the second doped conductive layer in the groove away from the substrate.

[0077] Example 5

[0078] This example provides a solar cell. The only difference between this solar cell and Example 4 is that the maximum distance between the groove and the second surface is 20 μm, and the width of the groove is 40 μm.

[0079] Example 6

[0080] This example provides a solar cell. The only difference between this solar cell and Example 4 is that the maximum distance between the groove and the second surface is 13 μm, and the width of the groove is 35 μm.

[0081] Example 7

[0082] This embodiment provides a solar cell. The only difference between this solar cell and that of Example 4 is that the maximum distance between the above-mentioned groove and the above-mentioned second surface is 1 μm, and the width of the above-mentioned groove is 22 μm.

[0083] Example 8

[0084] This embodiment provides a solar cell, comprising: a substrate having opposite first and second surfaces, and the second surface has a groove;

[0085] A first doped conductive layer located on the first surface or on the second surface at least on one side of the groove;

[0086] A second doped conductive layer at least partially located in the groove, wherein the doping type of the first doped conductive layer is different from that of the second doped conductive layer;

[0087] A first electrode located on the side of the first doped conductive layer away from the substrate and in contact with the first doped conductive layer;

[0088] A second electrode at least partially located on the side of the second doped conductive layer in the groove away from the substrate;

[0089] At least a part of the surface of one of the first surface and the second surface is a matte surface structure, the matte surface structure includes a plurality of pyramid structures, and the maximum diameter of the orthographic projection of the pyramid structure on the substrate is 5 μm.

[0090] Example 9

[0091] This embodiment provides a solar cell. The only difference between this solar cell and that of Example 8 is that the maximum diameter of the orthographic projection of the above-mentioned pyramid structure on the substrate is 30 μm.

[0092] Example 10

[0093] This embodiment provides a solar cell. The only difference between this solar cell and that of Example 8 is that the maximum diameter of the orthographic projection of the above-mentioned pyramid structure on the substrate is 15 μm.

[0094] Example 11

[0095] This embodiment provides a solar cell. The only difference between this solar cell and that of Example 8 is that the maximum diameter of the orthographic projection of the above-mentioned pyramid structure on the substrate is 3 μm.

[0096] Comparative Example

[0097] This embodiment provides a solar cell, as Figure 4 shown in the structure, including: a substrate 10, and the substrate 10 has opposite first and second surfaces;

[0098] A first doped conductive layer 12, located on the first surface;

[0099] A second doped conductive layer 13, located on the second surface;

[0100] A first electrode 30, located on the side of the first doped conductive layer 12 away from the substrate 10 and in contact with the first doped conductive layer 12;

[0101] A second electrode 31, located on the side of the second doped conductive layer 13 away from the substrate 10 and in contact with the second doped conductive layer 13.

[0102] The performance of the solar cells in the above embodiments and comparative examples was tested, and the test results are shown in Table 1:

[0103] Table 1

[0104] Serial number of solar cell ETA FF Rs Comparative example 1 1 1 Example 1 1.005 1.005 0.92 Example 2 1.007 1.007 0.90 Example 3 1.01 1.01 0.85 Example 4 1.029 1.029 0.8 Example 5 1.061 1.061 0.57 Example 6 1.071 1.071 0.5 Example 7 1.024 1.024 0.83 Example 8 1.009 1.014 0.9 Example 9 1.004 1.01 0.83 Example 10 1.015 1.014 0.9 Example 11 1.002 1.002 0.83

[0105] It can be seen from the above experimental data that the photoelectric conversion efficiency in Embodiments 1 to 11 is higher than that in the comparative examples. It can be seen from the above experimental data that the conversion efficiency (ETA) and fill factor (FF) of Embodiments 1 to 11 are both higher than those in the comparative examples, indicating that the solar cell of the present application can reduce the carrier recombination loss and improve the photoelectric conversion efficiency. The series resistance (Rs) of Embodiments 1 to 11 is smaller than that of the comparative examples, indicating that the solar cell of the present application can reduce the series resistance of the solar cell. It should be noted that the above experimental data do not represent specific values and are used to represent the multiple relationship of the parameters between different embodiments.

[0106] It can also be seen from the above experimental data that compared with Embodiment 7, the conversion efficiency and fill factor of Embodiments 4 to 6 are greater, indicating that by using the groove depth and groove width within the scope of the present application, the conversion efficiency and fill factor can be made greater. In addition, according to the data of Embodiments 4 to 7, it can be known that if a smaller groove depth (such as 1 μm) and a smaller groove width (such as 22 μm) are used, their fill factor and conversion efficiency will not be significantly better than those of Embodiments 4 to 6. Therefore, the value ranges of the groove depth and groove width set in the present application are relatively reasonable and can ensure a larger conversion efficiency and fill factor.

[0107] It can also be seen from the above experimental data that, compared with Example 11, the conversion efficiency and fill factor of Examples 8-10 are greater, indicating that using the maximum diameter of the orthographic projection of the pyramid structure within the scope of the present application on the above-mentioned substrate can result in greater conversion efficiency and fill factor. In addition, according to the data of Examples 8-11, if a smaller maximum diameter (such as 3 μm) is used, its fill factor and conversion efficiency will not be significantly better than those of Examples 8-10. Therefore, the value range of the maximum diameter of the orthographic projection of the pyramid structure provided in the present application on the above-mentioned substrate is relatively reasonable, which can ensure relatively large conversion efficiency and fill factor.

[0108] In some other typical embodiments of the present application, a schematic flow chart of a method for preparing a solar cell is provided, as Figure 5 shown, and the method includes the following steps:

[0109] Step S101, providing a preliminary substrate, where the preliminary substrate has opposite first and second surfaces;

[0110] Specifically, the material of the preliminary substrate may include single crystal silicon, perovskite, polycrystalline silicon, etc., and methods such as single crystal growth, epitaxial growth, and thin film deposition can be selected to prepare the substrate on the preliminary substrate.

[0111] Step S102, removing a part of the preliminary substrate on the side of the second surface to obtain a substrate 10 having a groove 11.

[0112] To obtain a structure as Figure 6 shown;

[0113] Specifically, the material of the substrate 10 may include single crystal silicon, perovskite, polycrystalline silicon, etc., and methods such as single crystal growth, epitaxial growth, and thin film deposition can be selected to make the substrate. For example, molecular beam epitaxy or metal-organic chemical vapor deposition is used to grow a multi-layer structure. By precisely controlling growth conditions such as temperature, pressure, and gas flow rate, a substrate with a specific crystal structure and doping level can be fabricated to meet the requirements of different applications, and those skilled in the art can make selections according to different situations. The groove 11 is formed by methods such as laser and etching to form a grooving or patterning structure, and precise laser patterning is performed by setting different-shaped light spots and adjusting parameters such as laser wavelength, pulse width, and power, so as to prepare grooves 11 with different shapes. The groove 11 can be any regular or irregular shape such as triangular, hexagonal, circular, etc., and the groove 11 can be located on the second surface of the substrate 10.

[0114] Step S103, forming a first doped conductive layer 12 in part of the groove 11 on the first surface or the second surface to obtain a structure as Figure 7 shown;

[0115] Specifically, the first doped conductive layer 12 can be doped with P-type doping ions or N-type doping ions and formed in some of the above-mentioned grooves 11 on the first surface or the second surface of the above-mentioned substrate 10 by means of diffusion method, plasma enhanced chemical vapor deposition, physical vapor deposition, etc. The N-type doping ions can be pentavalent elements such as phosphorus (P), bismuth (Bi), arsenic (As), or antimony (Sb), and the P-type doping ions can be trivalent elements such as boron (B), aluminum (Al), indium (In), or gallium (Ga).

[0116] Step S104, form a second doped conductive layer 13 in at least some of the above-mentioned grooves 11, wherein the doping type of the above-mentioned first doped conductive layer 12 is different from that of the above-mentioned second doped conductive layer 13, to obtain a structure as Figure 8 shown;

[0117] Specifically, the second doped conductive layer 13 can be at least partially formed in the groove 11 by doping P-type doping ions or N-type doping ions through diffusion method, plasma enhanced chemical vapor deposition, physical vapor deposition, etc. The N-type doping ions can be pentavalent elements such as phosphorus (P), bismuth (Bi), arsenic (As), or antimony (Sb), and the P-type doping ions can be trivalent elements such as boron (B), aluminum (Al), indium (In), or gallium (Ga). The doping type of the above-mentioned first doped conductive layer 12 is different from that of the above-mentioned second doped conductive layer 13, so as to form an electric field in the substrate, promote the transport of carriers, and further improve the photoelectric conversion efficiency.

[0118] Step S105, form a first electrode 30 on the side of the above-mentioned first doped conductive layer 12 away from the above-mentioned substrate 10, and one end of the above-mentioned first electrode 30 is in contact with the first doped conductive layer 12, to obtain a structure as Figure 9 shown;

[0119] Specifically, the first electrode 30 can include one or more of aluminum, silver, gold, nickel, molybdenum, or copper, and is formed on the side of the first doped conductive layer 12 away from the above-mentioned substrate 10. The above-mentioned first electrode 30 is in contact with the first doped conductive layer 12, reducing the resistance and further improving the photoelectric conversion efficiency.

[0120] Step S106, form a second electrode 31 in at least some of the above-mentioned second surface grooves 11, to obtain a structure as Figure 10 shown.

[0121] Specifically, the above-mentioned second electrode 31 can include one or more of aluminum, silver, gold, nickel, molybdenum, or copper, and the material of the above-mentioned second electrode 31 is the same as or different from that of the first electrode.

[0122] In a specific embodiment of the present application, on the basis of including the above steps S101 to S106, the above step S102 is further refined. This step includes: S1021, removing a part of the above-mentioned preliminary substrate on one side of the second surface to obtain a substrate with a groove, including: setting a mask layer 22 on the second surface; using the mask layer 22 as a mask, and adopting a laser process to remove a part of the above-mentioned preliminary substrate to obtain as Figure 11 the structure shown.

[0123] Specifically, the mask layer 22 can be formed on the second surface of the preliminary substrate by methods such as thermal oxidation, chemical vapor deposition or physical vapor deposition. The mask layer 22 can be one or more of silicon oxide, silicon oxynitride, silicon nitride or aluminum oxide. After the mask layer 22 is formed, a part of the above-mentioned preliminary substrate can be removed by parameters such as the spot shape of the laser, laser power, wavelength, temperature, scanning rate, etc. to obtain as Figure 6 the structure shown. By setting the mask layer 22, the erosion of the preliminary substrate by the laser and chemical solution can be reduced, the accuracy of laser patterning can be improved, thereby enhancing the stability of the battery and further improving the photoelectric conversion efficiency.

[0124] In some other typical embodiments of the present application, a photovoltaic module is provided, as Figure 12 shown. The photovoltaic module includes: a battery string formed by connecting a plurality of the above-mentioned solar cells 40 in any one of the above embodiments, wherein the above-mentioned solar cell 40 is a passivated contact cell or a back contact cell;

[0125] Specifically, two adjacent battery strings can be electrically connected through a conductive band 402. In some embodiments, the electrodes of the same polarity of the solar cell 40 face the same direction, and the conductive band 402 is respectively connected to the electrodes of different polarities of two adjacent solar cells 40. In some other embodiments, the solar cells 40 can also be arranged according to the electrodes of different polarities, that is, the electrodes of adjacent battery chips are sequentially arranged in the order of the first polarity, the second polarity, and the first polarity, then the conductive band 402 connects two adjacent battery chips on the same side. In some embodiments, there is no gap between the battery chips, that is, the battery chips overlap each other. The above-mentioned passivated contact cell can be a TOPcon cell, a PERC cell, etc., and the above-mentioned back contact cell can be an IBC cell and an HJT cell, etc.

[0126] A packaging layer 41 for covering the surface of the above-mentioned battery string;

[0127] Specifically, the encapsulation layer 41 includes a first encapsulation layer and a second encapsulation layer. The first encapsulation layer covers one of the front or back surfaces of the solar cell string, and the second encapsulation layer covers the other of the front or back surfaces of the cell string. Specifically, the material of the encapsulation layer 41 can be at least one of organic encapsulation films such as polyvinyl butyral (abbreviated as PVB), ethylene-vinyl acetate copolymer (abbreviated as EVA) film, polyolefin elastomer (abbreviated as POE) film, or polyethylene terephthalate (abbreviated as PET) film. In practical applications, there is a gap between the first encapsulation layer and the second encapsulation layer before lamination, but after lamination, the first encapsulation layer and the second encapsulation layer together form the above-mentioned encapsulation layer 41.

[0128] The cover plate 42 is used to cover the surface of the above-mentioned encapsulation layer 41 on the side away from the above-mentioned cell string.

[0129] Specifically, the material of the cover plate 42 can be a light-transmitting material such as glass or plastic. In addition, the surface of the cover plate 42 facing the encapsulation layer 41 can be an uneven surface, so as to increase the utilization rate of incident light. The cover plate 42 includes a first cover plate and a second cover plate. The first cover plate is disposed opposite to the first encapsulation layer, and the second cover plate is disposed opposite to the second encapsulation layer.

[0130] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0131] 1. The solar cell of the present application includes: a substrate having opposite first and second surfaces, and the second surface has a groove; a first doped conductive layer located on the first surface or on the second surface at least on one side of the groove; a second doped conductive layer at least partially located in the groove, wherein the doping types of the first doped conductive layer and the second doped conductive layer are different; a first electrode located on the side of the first doped conductive layer away from the substrate and in contact with the first doped conductive layer; and a second electrode at least partially located on the side of the second doped conductive layer in the groove away from the substrate. Since the substrate has a groove and the second doped conductive layer is located in the groove, the distance of the second doped conductive layer relative to the second surface can be increased; in addition, since the second electrode is also located in the groove, compared with the prior art, the contact area between the electrode and the emitter can be increased. Since the series resistance is inversely proportional to the contact area between the electrode and the emitter, the above setting can reduce the series resistance of the solar cell, improve the output power and output voltage, thereby improving the fill factor of the solar cell and achieving the technical effect of improving the efficiency of the solar cell.

[0132] 2. Preparation method of the solar cell of the present application: Provide a preliminary substrate, remove a part of the preliminary substrate on one side of the second surface to obtain a substrate with grooves; form a first doped conductive layer in part of the grooves on the first surface or the second surface; form a second doped conductive layer in at least part of the grooves, form a first electrode on the side of the first doped conductive layer away from the substrate, and one end of the first electrode is in contact with the first doped conductive layer; form a second electrode in at least part of the second grooves. Since the substrate has grooves and the second doped conductive layer is located in the grooves, the distance of the second doped conductive layer relative to the second surface can be increased; in addition, since the second electrode is also located in the grooves, compared with the prior art, the contact area between the electrode and the emitter can be increased. Since the series resistance is inversely proportional to the contact area between the electrode and the emitter, the above settings can reduce the series resistance of the solar cell, improve the output power and output voltage, thereby increasing the fill factor of the solar cell and achieving the technical effect of improving the efficiency of the solar cell.

[0133] The foregoing are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A solar cell, characterized in that, Comprising: A substrate having opposite first and second surfaces, wherein the second surface has a groove; A first doped conductive layer located on the first surface or on the second surface at least on one side of the groove; A second doped conductive layer at least partially located in the groove, wherein the doping type of the first doped conductive layer is different from the doping type of the second doped conductive layer; A first electrode located on the side of the first doped conductive layer away from the substrate and in contact with the first doped conductive layer; A second electrode at least partially located on the side of the second doped conductive layer in the groove away from the substrate.

2. The solar cell according to claim 1, characterized in that, The portion of the first doped conductive layer is located on a partial area of the first surface, and the second doped conductive layer is also located on the second surface on both sides of the groove.

3. The solar cell according to claim 2, characterized in that, There are a plurality of the grooves, and there is a gap between any two of the grooves.

4. The solar cell according to claim 1, characterized in that, The first doped conductive layer is located on the second surface on both sides of the groove and has a gap from the second doped conductive layer.

5. The solar cell according to claim 1, wherein The shape of the cross-section of the groove in a predetermined direction is one of a circle, an ellipse, and a polygon, and the predetermined direction is perpendicular to the direction of the thickness of the substrate.

6. The solar cell according to claim 1, characterized in that, The maximum distance between the groove and the second surface is 3 - 20 μm, and the width of the groove is 30 - 40 μm.

7. The solar cell according to claim 1, characterized in that, At least a partial surface of one of the first surface and the second surface is a matte structure, the matte structure includes a plurality of pyramid structures, and the maximum diameter of the positive projection of the pyramid structure on the substrate is 5 - 30 μm.

8. A method for preparing a solar cell, characterized in that, Comprising: Providing a preliminary substrate having opposite first and second surfaces; Removing a part of the preliminary substrate on the side of the second surface to obtain a substrate with a groove; Forming a first doped conductive layer on the first surface or in a partial groove of the second surface; Forming a second doped conductive layer at least in a partial groove, wherein the doping type of the first doped conductive layer is different from the doping type of the second doped conductive layer; Forming a first electrode on the side of the first doped conductive layer away from the substrate, and one end of the first electrode is in contact with the first doped conductive layer; Forming a second electrode at least in a partial groove of the second surface.

9. The manufacturing method of the solar cell according to claim 8, characterized in that, Removing a part of the preliminary substrate on the side of the second surface to obtain a substrate with a groove, including: Providing a mask layer on the second surface; Using a laser process to remove a part of the preliminary substrate with the mask layer as a mask.

10. Photovoltaic module, characterized in that, Comprising: A battery string formed by connecting the solar cells according to any one of claims 1 to 7, wherein the solar cell is a passivated contact cell or a back contact cell; An encapsulation layer for covering the surface of the battery string; A cover plate for covering the surface on the side of the encapsulation layer away from the battery string.

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