Solar cell and photovoltaic module

Abstract

The present application belongs to the technical field of solar cells. Provided are a solar cell and a photovoltaic module. The solar cell comprises: a semiconductor substrate; a tunneling oxide layer located on at least one surface of the semiconductor substrate; and a doped polysilicon layer located on the side of the tunneling oxide layer away from the semiconductor substrate, wherein silicon-containing raised particles are formed on at least a part of the surface of the doped polysilicon layer away from the tunneling oxide layer. The photovoltaic module provided by the present application comprises the solar cell. In the present application, the silicon-containing raised particles are formed on at least a part of the surface of the doped polysilicon layer away from the tunneling oxide layer, so as to improve the light-trapping effect of at least one surface of the solar cell, thereby increasing the bifaciality ratio of the solar cell.

Description

Solar cell and photovoltaic module

[0001] Cross-reference to Related Applications

[0002] This application claims priority to Chinese Patent Application No. 202411287736.1, filed on September 13, 2024, entitled “Solar cell and photovoltaic module” and Chinese Patent Application No. 202411546430.3, filed on October 31, 2024, entitled “Solar cell and photovoltaic module”, the contents of which are hereby incorporated by reference in their entirety. TECHNICAL FIELD

[0003] The present application relates to a solar cell, in particular to a solar cell and a photovoltaic module. BACKGROUND

[0004] The tunneling oxide passivation contact structure (TOPCon structure) is composed of an ultrathin tunneling oxide layer and a doped polysilicon layer. This structure can be applied to various types of cells to form different cell types, such as TOPCon solar cells, local TOPCon solar cells, tunneling back contact solar cells (TBC solar cells), or back contact solar cells (BC solar cells) with a TOPCon structure in one area, etc.

[0005] Before performing a high-temperature thin film deposition process, an etching process is performed to polish the surface of the silicon substrate. During polishing, a tower base structure is formed on the surface of the silicon substrate. Although the tower base structure is beneficial for forming good tunneling passivation and contact after deposition of the tunneling oxide and the polysilicon thin film, the tower base structure weakens the light trapping effect on the surface of the cell, thus reducing the bifaciality of the solar cell. SUMMARY

[0006] In view of this, in order to improve the bifaciality of the solar cell, the present application provides a solar cell and a photovoltaic module.

[0007] According to an embodiment of the present application, a solar cell is provided, comprising: a semiconductor substrate; a tunneling oxide layer located on at least one surface of the semiconductor substrate; a doped polysilicon layer located on a side of the tunneling oxide layer away from the semiconductor substrate; wherein at least a part of the surface of the doped polysilicon layer away from the tunneling oxide layer has silicon-containing protruding particles.

[0008] According to an embodiment of the present application, the surface of the doped polysilicon layer located at least at a position close to one corner or one edge of the semiconductor substrate has silicon-containing protruding particles.

[0009] According to embodiments of the present application, the surface of the doped polysilicon layer away from the tunneling oxide layer further has a plurality of relief structures; the height of the silicon-containing protruding particles is greater than the height of the relief structures.

[0010] According to embodiments of the present application, the doped polysilicon layer includes a plurality of first doped polysilicon layers and a plurality of second doped polysilicon layers alternately and spacedly distributed along a first direction, one of the first doped polysilicon layers and the second doped polysilicon layers is N-type, and the other of the first doped polysilicon layers and the second doped polysilicon layers is P-type; the surface of the first doped polysilicon layer and / or the second doped polysilicon layer has silicon-containing protruding particles.

[0011] According to embodiments of the present application, at least one surface of the semiconductor substrate has a non-pyramidal textured structure, the non-pyramidal textured structure includes a plurality of substructures, the doped polysilicon layer on the top surface of the substructure has silicon-containing protruding particles; the distribution density of the silicon-containing protruding particles on the N-type doped polysilicon layer on the top surface of the substructure is greater than the distribution density of the silicon-containing protruding particles on the P-type doped polysilicon layer on the top surface of the substructure.

[0012] According to embodiments of the present application, at least one surface of the semiconductor substrate has a non-pyramidal textured structure, the non-pyramidal textured structure includes a plurality of substructures, the doped polysilicon layer on the top surface of the substructure has silicon-containing protruding particles; the distribution density of the silicon-containing protruding particles on the doped polysilicon layer on the top surface of at least one substructure is 0.1-0.5 / μm 2 .

[0013] According to embodiments of the present application, the number of protruding particles is less than the number of relief structures under the same cross-sectional length.

[0014] According to embodiments of the present application, the above-mentioned solar cell further includes:

[0015] The passivation anti-reflection layer is located on the surface of the doped polysilicon layer away from the semiconductor substrate; wherein the height of the silicon-containing protruding particles is greater than the thickness of the passivation anti-reflection layer, and / or the height of the silicon-containing protruding particles is less than 3 times the thickness of the passivation anti-reflection layer.

[0016] In some embodiments, the doped polysilicon layer includes a plurality of first doped polysilicon layers and a plurality of second doped polysilicon layers alternately and spacedly distributed along a first direction, one of the first doped polysilicon layers and the second doped polysilicon layers is N-type, and the other of the first doped polysilicon layers and the second doped polysilicon layers is P-type;

[0017] At least a part of the surface of the N-type doped polysilicon layer away from the tunneling oxide layer has a plurality of pit structures, and / or at least a part of the surface of the P-type doped polysilicon layer away from the tunneling oxide layer has a plurality of pit structures.

[0018] In some embodiments, the at least one surface of the semiconductor substrate has a non-pyramidal textured structure, the non-pyramidal textured structure comprises a plurality of sub-structures, a doped polysilicon layer on a top surface of the sub-structures has a plurality of pit structures, and a distribution density of the pit structures on the top surface of the sub-structures is 50000 / mm2-300000 / mm2.

[0019] In some embodiments, the at least one surface of the semiconductor substrate has a non-pyramidal textured structure, the non-pyramidal textured structure comprises a plurality of sub-structures,

[0020] A doped polysilicon layer of N type on a top surface of at least a portion of the sub-structures has a plurality of pit structures away from a surface of the tunneling oxide layer, and a doped polysilicon layer of P type on a top surface of at least a portion of the sub-structures has a plurality of pit structures away from a surface of the tunneling oxide layer;

[0021] The distribution density of the pit structures of the doped polysilicon layer of N type on the top surface of the sub-structures is greater than the distribution density of the pit structures of the doped polysilicon layer of P type on the top surface of the sub-structures.

[0022] In some embodiments, the above-mentioned solar cell further comprises: a passivation anti-reflection layer on a surface of the doped polysilicon layer away from the semiconductor substrate.

[0023] The pit structures are filled with the passivation anti-reflection layer.

[0024] According to embodiments of the present application, the silicon-containing protruding particles comprise at least one of C element, N element and O element.

[0025] According to embodiments of the present application, the silicon-containing protruding particles comprise a third main group element and / or a fifth main group element.

[0026] According to embodiments of the present application, the height of the silicon-containing protruding particles ranges from 150 nm to 450 nm.

[0027] The length of the relief structure in a direction parallel to the surface of the semiconductor substrate 1 ranges from 70 nm to 500 nm.

[0028] The height of the relief structure ranges from 20 nm to 60 nm.

[0029] According to embodiments of another aspect of the present application, a photovoltaic module is provided, comprising the above-mentioned solar cell.

[0030] According to embodiments of the present application, the photovoltaic module comprises a solder strip, the solder strip is suitable for electrically connecting two adjacent solar cells, and in a planar direction of the at least one surface of the semiconductor substrate, the solder strip is spaced apart from the doped polysilicon layer having the silicon-containing protruding particles.

[0031] According to the back contact solar cell provided by the above-mentioned embodiment of the present application, the light trapping effect of at least one surface of the solar cell is improved by forming the silicon-containing protruding particles on at least a part of the surface of the doped polysilicon layer away from the tunneling oxide layer, so as to further improve the bifaciality of the solar cell. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings described below only relate to some of the embodiments of the present application, but not limit the present application.

[0033] FIG. 1 is a schematic cross-sectional view of a back contact solar cell according to an embodiment of the present application;

[0034] FIG. 2 is a scanning electron microscope (SEM) image of a surface of a doped polysilicon layer near an edge of a semiconductor substrate according to an embodiment of the present application;

[0035] FIG. 3 is another SEM image of the surface of the doped polysilicon layer near the edge of the semiconductor substrate according to an embodiment of the present application;

[0036] FIG. 4A is yet another SEM image of the surface of the doped polysilicon layer near the edge of the semiconductor substrate according to an embodiment of the present application;

[0037] FIG. 4B is a height test image of the surface of the doped polysilicon layer in FIG. 4A according to an embodiment of the present application;

[0038] FIG. 5 is still another SEM image of the surface of the doped polysilicon layer near the edge of the semiconductor substrate according to an embodiment of the present application;

[0039] FIG. 6 is a SEM image of a side view of the surface of the doped polysilicon layer near the edge of the semiconductor substrate according to an embodiment of the present application;

[0040] FIG. 7 is a schematic cross-sectional view of a TOPCon solar cell according to an embodiment of the present application;

[0041] FIG. 8 is yet another SEM image of the surface of the doped polysilicon layer near the edge of the semiconductor substrate according to an embodiment of the present application;

[0042] FIG. 9A is a SEM image of a partial area in FIG. 8; and

[0043] FIG. 9B is an EDS test result image of a site in FIG. 9A.

[0044] Legend: 1-semiconductor substrate; 2-tunneling oxide layer; 3-doped polysilicon layer; 31-minority carrier region; 32-majority carrier region; 33-isolation region; 34-first doped polysilicon layer; 35-second doped polysilicon layer; 4-non-electrode collection region; 10-first electrode; 20-second electrode; 5-emitter; 6-first passivation layer; 7-second passivation layer; 30-third electrode; 40-fourth electrode. DETAILED DESCRIPTION

[0045] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to specific examples and with reference to the drawings. However, the present application can be implemented in different forms, and should not be interpreted as being limited to the examples presented herein. On the contrary, these examples are presented to make the application complete and fully, and to fully convey the scope of the present application to those skilled in the art. In the drawings, the sizes and relative sizes of the layers and regions can be exaggerated for clarity, and the same reference signs represent the same elements throughout.

[0046] The terms used herein are merely used to describe specific examples, and are not intended to limit the present application. The terms "comprise", "contain", and the like as used herein indicate the presence of the stated features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0047] In the related art, the double-side rate of a solar cell is improved from the perspectives of tower base optimization and grid line design. From the perspective of tower base optimization, a tower base with finer and greater height differences between adjacent towers is prepared on a semiconductor substrate (silicon substrate) by controlling the polishing effect. This method improves the light trapping effect on the surface of the cell, but the tower base with finer and greater height differences between adjacent towers is prone to cause the uniformity of the subsequently deposited thin film (tunneling oxide layer and polysilicon layer) to decrease, thereby causing tunneling, passivation and contact problems. From the perspective of grid line design, the width of the main grid and the auxiliary grid is mainly narrowed. This method can improve light absorption, but the increase of the aspect ratio of the grid lines puts forward more requirements for the formability of the paste. At the same time, finer grid lines also increase the contact resistance of the cell.

[0048] Therefore, it is necessary to provide a solar cell and a photovoltaic module to solve the technical problem of urgently improving the double-side rate of a solar cell in the related art.

[0049] FIG. 1 is a cross-sectional schematic view of a back contact solar cell according to an embodiment of the present application.

[0050] According to an exemplary embodiment of the present application, the present application provides a solar cell, as shown in FIG. 1 or FIG. 5, comprising:

[0051] a semiconductor substrate 1;

[0052] a tunneling oxide layer 2 on at least one surface of the semiconductor substrate 1;

[0053] a doped polysilicon layer 3 on a surface of the tunneling oxide layer 2 away from the semiconductor substrate 1; wherein the doped polysilicon layer 3 has silicon-containing protruding particles on at least a portion of the surface thereof away from the tunneling oxide layer 2.

[0054] According to an embodiment of the present application, referring to FIG. 1, the solar cell is, for example, a back contact solar cell. The semiconductor substrate 1 has opposite first and second surfaces, and the tunneling oxide layer 2 is on the second surface of the semiconductor substrate 1, which is, in this embodiment, the back surface of the back contact solar cell.

[0055] In some embodiments, the surface of the doped polysilicon layer 3 away from the tunneling oxide layer 2 further has a plurality of relief structures; the height of the silicon-containing protruding particles is greater than the height of the relief structures.

[0056] In some embodiments, the surface of the doped polysilicon layer 3 away from the tunneling oxide layer 2 further has a plurality of relief structures; the width of the silicon-containing protruding particles is less than the width of the relief structures.

[0057] According to an embodiment of the present application, the relief structures can be, for example, silicon grains. The length of the relief structures in the direction parallel to the surface of the semiconductor substrate 1 is 70-500 nm, for example, 70 nm, 100 nm, 150 nm, 200 nm, or 500 nm. The height of the relief structures is 20-60 nm, for example, 20 nm, 30 nm, 40 nm, 50 nm, or 60 nm.

[0058] According to an embodiment of the present application, the surface of the doped polysilicon layer 3 away from the tunneling oxide layer 2 has a plurality of relief structures, and the height of the relief structures is generally small, i.e., the relief structures have a slow relief degree, and it is difficult to improve the light trapping effect by the relief structures, and the relief structures have a limited contribution to the double-sided rate of the solar cell.

[0059] According to an embodiment of the present application, the surface of the doped polysilicon layer 3 away from the tunneling oxide layer 2 has a plurality of relief structures, and the width of the relief structures is generally wide, i.e., the relief structures have a slow relief degree, and it is difficult to improve the light trapping effect by the relief structures, and the relief structures have a limited contribution to the double-sided rate of the solar cell. The present application improves the light trapping effect of the doped polysilicon layer and the double-sided rate of the solar cell by the silicon-containing protruding particles with a higher height and / or a narrower width, while not damaging the tunneling passivation of the doped polysilicon layer and improving the photoelectric conversion effect of the solar cell.

[0060] The black dots shown in FIG. 3 and the white particles shown in FIG. 6 represent the silicon-containing protruding particles. The silicon-containing protruding particles have a partial spherical structure, such as a semi-spherical structure; the height of the silicon-containing protruding particles (approximately the radius of the silicon-containing protruding particles) is 150 nm to 450 nm, for example, can be 150 nm, 200 nm, 300 nm, 400 nm, 450 nm, but is not limited to the values mentioned.

[0061] According to the embodiments of the present application, the height of the silicon-containing protruding particles is 150 nm to 450 nm, which can achieve a good light-trapping effect. If the height of the silicon-containing protruding particles is too small, for example, less than 150 nm, the sunlight cannot be refracted multiple times at the silicon-containing protruding particles and the sidewall of the base, and it is difficult to achieve the light-trapping effect. If the silicon-containing protruding particles are too large, the film quality of the doped polysilicon is reduced, which is not conducive to the photoelectric conversion efficiency of the solar cell.

[0062] According to the embodiments of the present application, at least a part of the surface of the doped polysilicon layer 3 of the solar cell away from the tunneling oxide layer 2 has silicon-containing protruding particles. As shown in FIG. 4B, there are two high protrusions (the areas pointed by the arrows in FIG. 4B) on the surface of the doped polysilicon layer, which correspond to the two silicon-containing protruding particles (the two black dots pointed by the arrows in FIG. 4A) on the surface of the doped polysilicon layer in FIG. 4A. This indicates that the surface of the doped polysilicon layer away from the tunneling oxide layer has silicon-containing protruding particles. As shown in FIG. 6, the white dots represent the silicon-containing protruding particles, the height of the silicon-containing protruding particles is greater than the height of the relief structure, and the height of the silicon-containing protruding particles is close to the height of the pyramid structure (the height of the pyramid structure for light trapping is usually less than 1 μm). The incident sunlight is refracted multiple times at the silicon-containing protruding particles, more sunlight is incident on the semiconductor substrate 1, the light-trapping effect of the at least one surface of the solar cell is increased, and the bifaciality of the solar cell is improved.

[0063] According to the embodiments of the present application, the surface of the doped polysilicon layer 3 at least at a position close to one corner or one edge of the semiconductor substrate 1 has silicon-containing protruding particles.

[0064] According to the embodiments of the present application, the distance between the silicon-containing protruding particles and the edge of the semiconductor substrate 1 is less than 3 mm, for example, can be 1 mm, 2 mm, 3 mm, but is not limited to the values mentioned.

[0065] As shown in FIG. 2, the second surface of the semiconductor substrate 1 has a non-pyramidal textured structure, the non-pyramidal textured structure includes a plurality of substructures (as shown by the rectangles in FIG. 2), the tunneling oxide layer 2 and the doped polysilicon layer 3 are sequentially deposited on the second surface of the semiconductor substrate 1. The surface of the doped polysilicon layer 3 close to the edge of the semiconductor substrate 1 has a plurality of silicon-containing protruding particles (as shown by the black dots in FIG. 2).

[0066] It should be noted that the silicon-containing protruding particles can cause the refractive index of the incident light to change, and therefore, too many silicon-containing protruding particles on a large area can cause the color difference problem of the battery sheet. Specifically, the silicon-containing protruding particles cause the surface roughness of the doped polysilicon layer to be greater, so that the doped polysilicon layer reflects light of different wavelengths differently, causing the color difference problem of the battery sheet. Therefore, by controlling the silicon-containing protruding particles to be within a suitable range (the silicon-containing protruding particles are within a range of 3 mm from the edge of the semiconductor substrate 1), the light trapping effect of the battery surface can be increased, the double-sided rate of the battery can be improved, and the appearance defect problem of the final battery product caused by the color difference problem can be avoided.

[0067] According to an embodiment of the present application, referring to FIG. 1, the back contact solar cell includes two non-electrode collection regions 4 on the second surface of the semiconductor substrate 1, and an electrode collection region between the two non-electrode collection regions 4, the electrode collection region includes a plurality of minority carrier regions 31 and a plurality of majority carrier regions 32 alternately distributed along a first direction, and the minority carrier regions 31 and the majority carrier regions 32 have an isolation region 33 therebetween.

[0068] According to an embodiment of the present application, the doped polysilicon layer 3 includes a first doped polysilicon layer 34 and a second doped polysilicon layer 35; wherein the first doped polysilicon layer 34 for collecting and leading out the minority carrier is arranged in the minority carrier region 31; the second doped polysilicon layer 35 for collecting and leading out the majority carrier is arranged in the majority carrier region 32, wherein the first doped polysilicon layer 34 and the second doped polysilicon layer 35 are opposite in conductive type, one of the first doped polysilicon layer 34 and the second doped polysilicon layer 35 is N-type, and the other of the first doped polysilicon layer 34 and the second doped polysilicon layer 35 is P-type. For example, the conductive type of the first doped polysilicon layer 34 can be N-type, and the conductive type of the second doped polysilicon layer 35 is P-type; or the conductive type of the first doped polysilicon layer 34 can be P-type, and the conductive type of the second doped polysilicon layer 35 is N-type.

[0069] According to an embodiment of the present application, the semiconductor substrate 1 can be an N-type semiconductor substrate or a P-type semiconductor substrate. The conductive type of the semiconductor substrate 1 is the same as the conductive type of the second doped polysilicon layer 35.

[0070] In the embodiments of the present application, the semiconductor substrate 1 is N-type, the first doped polysilicon layer 34 is P-type, and the second doped polysilicon layer 35 is N-type.

[0071] According to an embodiment of the present application, the surface of the first doped polysilicon layer 34 and / or the second doped polysilicon layer 35 has silicon-containing protruding particles.

[0072] According to an embodiment of the present application, the surface of the first doped polysilicon layer 34 has silicon-containing protruding particles.

[0073] According to embodiments of the present application, the surface of the second doped polysilicon layer 35 has silicon-containing protruding particles.

[0074] According to embodiments of the present application, the surface of the first doped polysilicon layer 34 and the surface of the second doped polysilicon layer 35 both have silicon-containing protruding particles.

[0075] In some embodiments, at least a part of the surface of the N-type doped polysilicon layer away from the tunneling oxide layer has a plurality of protruding structures, which can increase the effective light absorption of the N-type doped polysilicon layer, improve the bifaciality of the solar cell; and the protruding structures can increase the contact area of the N-type doped polysilicon layer and the metal electrode, which is conducive to reducing the contact resistance. Moreover, the surface of the P-type doped polysilicon layer away from the tunneling oxide layer does not have protruding structures, and the surface of the P-type doped polysilicon layer is smoother, which is conducive to achieving better tunneling passivation effect.

[0076] In some embodiments, according to the actual performance requirements of the solar cell, the surface of the N-type doped polysilicon layer can be set to not have protruding structures; and at least a part of the surface of the P-type doped polysilicon layer away from the tunneling oxide layer 2 has a plurality of protruding structures. For the N-type substrate, the P-type doped polysilicon layer serves as an emitter region, and the surface thereof has a plurality of protruding structures, which increases the light absorption of the P-type region, excites more carriers, improves the bifaciality, and further reduces the contact resistance of the P-type region.

[0077] According to embodiments of the present application, the surface of the at least two first doped polysilicon layers 34 has silicon-containing protruding particles.

[0078] According to embodiments of the present application, the surface of the at least two second doped polysilicon layers 35 has silicon-containing protruding particles.

[0079] According to embodiments of the present application, the surface of the first doped polysilicon layer 34 and / or the surface of the second doped polysilicon layer 35 has silicon-containing protruding particles, and the incident light will refract multiple times on the silicon-containing protruding particles, and thus more light will be incident on the surface of the semiconductor substrate 1. Therefore, the more the doped polysilicon layers having silicon-containing protruding particles, the more the light trapping effect of the second surface of the cell can be increased, and the bifaciality of the cell can be improved.

[0080] According to embodiments of the present application, at least one surface of the semiconductor substrate 1 has a non-pyramidal textured structure, the non-pyramidal textured structure includes a plurality of substructures, the doped polysilicon layer on the top surface of the substructure has silicon-containing protruding particles; and the distribution density of the silicon-containing protruding particles on the N-type doped polysilicon layer located on the top surface of the substructure is greater than the distribution density of the silicon-containing protruding particles on the P-type doped polysilicon layer located on the top surface of the substructure.

[0081] According to the embodiments of the present application, in the manufacturing process of the back contact solar cell, the doping concentration of the N-type region doped polysilicon layer is higher than that of the P-type region doped polysilicon layer, and the N-type region causes more serious Auger recombination. By controlling the distribution density of the silicon-containing protruding particles on the N-type doped polysilicon layer to be greater than that on the P-type doped polysilicon layer, the light trapping effect of the N-type region can be increased, the loss of Auger recombination of the N-type region can be compensated, the difference between the light trapping effects of the N-type region and the P-type region can be reduced, the number of collected carriers of the N-type region can be increased, and thus the photoelectric conversion efficiency of the back contact solar cell can be improved.

[0082] According to the embodiments of the present application, at least one surface of the semiconductor substrate 1 has a non-pyramidal texture structure, the non-pyramidal texture structure includes a plurality of substructures, and the doped polysilicon layer on the top surface of the substructure has silicon-containing protruding particles; the distribution density of the silicon-containing protruding particles on the doped polysilicon layer on the top surface of at least one substructure is 0.1-0.5 / μm 2 , for example, 0.1 / μm 2 , 0.2 / μm 2 , 0.3 / μm 2 , 0.4 / μm 2 , or 0.5 / μm 2 , but is not limited to the values. The top surface refers to a complete polygonal or complete arc structure that can be observed in the top view of the cell product, which corresponds to the surface of the silicon substrate that is recessed towards the inside of the silicon substrate.

[0083] According to the embodiments of the present application, under the same cross-sectional length, the distribution number of the protruding particles is less than that of the undulating structure. For example, referring to FIG. 5, under the same magnification and the same window length, the distribution number of the undulating structure is greater than that of the silicon-containing protruding particles.

[0084] It should be noted that the doped polysilicon layer on the bottom surface, the top surface and the side surface of the substructure of the non-pyramidal texture structure can be distributed with silicon-containing protruding particles. In order to facilitate characterization, the present application selects the top surface of the substructure to quantify the distribution density of the silicon-containing protruding particles. The bottom surface corresponds to the surface of the silicon substrate that is away from the protrusion inside the silicon substrate.

[0085] According to the embodiments of the present application, the back surface of the solar cell has a tower base structure and silicon-containing protruding particles. The incident sunlight will refract multiple times at the silicon-containing protruding particles and the tower base side wall, so that more sunlight is incident on the surface of the semiconductor substrate. Therefore, the doped polysilicon layer with more dense silicon protruding particles can further increase the light trapping effect of the back surface of the cell and improve the bifacial rate of the solar cell.

[0086] In some embodiments, the at least part of the surface of the doped polysilicon layer 3 away from the tunneling oxide layer 2 has a plurality of pit structures, which can improve the light trapping effect of the at least one surface of the solar cell, and further improve the bifaciality of the solar cell.

[0087] In some embodiments, at least part of the surface of the N-type doped polysilicon layer and / or the P-type doped polysilicon layer has a plurality of pit structures. That is, at least part of the surface of the N-type doped polysilicon layer away from the tunneling oxide layer 2 has a plurality of pit structures, and the surface of the P-type doped polysilicon layer away from the tunneling oxide layer 2 has no pit structure; or, the surface of the N-type doped polysilicon layer away from the tunneling oxide layer 2 has no pit structure, and at least part of the surface of the P-type doped polysilicon layer away from the tunneling oxide layer 2 has a plurality of pit structures; or, at least part of the surface of the N-type doped polysilicon layer and the P-type doped polysilicon layer away from the tunneling oxide layer 2 has a plurality of pit structures, and the distribution density of the pit structures contained by the two is different.

[0088] In some embodiments, the depth of the pit structure is 80 nm to 150 nm, for example, can be 80 nm, 100 nm, 120 nm, 130 nm, 150 nm, but is not limited to the values mentioned.

[0089] In some embodiments, as shown in FIG. 5, the surface of the doped polysilicon layer near the edge of the semiconductor substrate has a dot-shaped or line-shaped pit structure, and the depth of the pit structure is less than the thickness of the doped polysilicon layer.

[0090] In some embodiments, the length of the pit structure in the direction parallel to the surface of the semiconductor substrate 1 is 150 nm to 630 nm, for example, can be 150 nm, 200 nm, 300 nm, 500 nm, 630 nm, but is not limited to the values mentioned.

[0091] According to the embodiments of the present application, the depth of the pit structure is greater than the height of the relief structure, that is, the relief degree of the pit structure is greater than the relief degree of the relief structure, and the pit structure is closer to the height of the pyramid (the height of the pyramid structure for light trapping is usually less than 1 μm), which further improves the light trapping effect and improves the bifaciality.

[0092] In some embodiments, at least part of the surface of the N-type doped polysilicon layer away from the tunneling oxide layer 2 has a plurality of pit structures, and the depth of the pit structure is greater than the height of the relief structure. And the surface of the P-type doped polysilicon layer away from the tunneling oxide layer 2 has no pit structure.

[0093] In the embodiments of the present application, the N-type doped polysilicon layer has a plurality of pit structures on at least a part of the surface away from the tunneling oxide layer, which can increase the effective light absorption of the N-type doped polysilicon layer, improve the bifaciality of the solar cell, and increase the contact area between the N-type doped polysilicon layer and the metal electrode, thereby reducing the contact resistance. In addition, the surface of the P-type doped polysilicon layer away from the tunneling oxide layer does not have pit structures, and the surface of the P-type doped polysilicon layer is smoother, which is beneficial to achieve better tunneling passivation effect.

[0094] For the convenience of characterization, the top surface of the substructure of the non-pyramidal texture structure is selected to quantify the distribution density of the pit structure.

[0095] In some embodiments, the distribution density of the pit structure on the top surface of the substructure is 50000 / mm2-300000 / mm2. 2 That is, the distribution density of the pit structure of the N-type doped polysilicon layer or the pit structure of the P-type doped polysilicon layer can be selected from the above range. It should be noted that if the distribution density of the pit structure is too large, the tunneling passivation effect of the passivation contact structure (the passivation contact structure includes the tunneling oxide layer and the doped polysilicon layer) will be reduced; if the distribution density of the pit structure is too small, the light trapping effect cannot be achieved. The pit structure with the specific distribution density of the present application can achieve the light trapping effect while not significantly reducing the tunneling passivation effect of the passivation contact structure.

[0096] In some embodiments, according to the actual performance requirements of the solar cell, the surface of the N-type doped polysilicon layer can not have pit structures; at least a part of the surface of the P-type doped polysilicon layer away from the tunneling oxide layer 2 has a plurality of pit structures, and the depth of the pit structure of the P-type doped polysilicon layer is greater than the height of the relief structure.

[0097] According to the embodiments of the present application, for the N-type substrate, the P-type doped polysilicon layer serves as an emitter region, and the surface thereof has a plurality of pit structures, which increases the light absorption of the P-type region, excites more carriers, improves the bifaciality, and further reduces the contact resistance of the P-type region.

[0098] In some embodiments, at least a part of the surface of the N-type doped polysilicon layer away from the tunneling oxide layer 2 has a plurality of pit structures, and at least a part of the surface of the P-type doped polysilicon layer away from the tunneling oxide layer 2 also has a plurality of pit structures; that is, at least a part of the top surface of the substructure has a plurality of pit structures on the surface of the N-type doped polysilicon layer, and at least a part of the top surface of the substructure has a plurality of pit structures on the surface of the P-type doped polysilicon layer; wherein the distribution density of the pit structure of the N-type doped polysilicon layer on the top surface of the substructure is greater than the distribution density of the pit structure of the P-type doped polysilicon layer on the top surface of the substructure.

[0099] In the embodiments of the present application, the doping concentration of the N-type region doped polysilicon layer is generally higher than that of the P-type region doped polysilicon layer, and the N-type region will cause more serious Auger recombination. By controlling the distribution density of the pit structure on the N-type doped polysilicon layer to be greater than that on the P-type doped polysilicon layer, the light trapping effect of the N-type region can be increased, the loss of Auger recombination of the N-type region can be compensated, the difference between the light trapping effects of the N-type region and the P-type region can be reduced, and the number of collected carriers of the N-type region can be increased, thereby improving the photoelectric conversion efficiency of the back contact solar cell.

[0100] In some embodiments, the solar cell described above further comprises: a passivation anti-reflection layer located on the surface of the doped polysilicon layer 3 away from the semiconductor substrate 1; wherein the height of the silicon-containing protruding particles is greater than the thickness of the passivation anti-reflection layer, and / or the height of the silicon-containing protruding particles is less than 3 times the thickness of the passivation anti-reflection layer.

[0101] According to the embodiments of the present application, after the passivation anti-reflection layer is deposited on the doped polysilicon layer 3, since at least a part of the surface of the doped polysilicon layer 3 away from the tunneling oxide layer 2 has silicon-containing protruding particles, at least a part of the surface of the deposited passivation anti-reflection layer will also form protruding particles.

[0102] According to the embodiments of the present application, the silicon-containing protruding particles have a certain height, which increases the contact area with the passivation anti-reflection layer, further increases the area of the passivation anti-reflection layer, and improves light absorption. Further, the height of the protruding particles is less than 3 times the thickness of the passivation anti-reflection layer, and the protruding particles are not too high. If the protruding particles are too high, it will affect the film uniformity of the passivation anti-reflection layer and reduce the passivation effect.

[0103] According to the embodiments of the present application, the passivation anti-reflection layer comprises a stack of aluminum oxide and one or more of silicon nitride, silicon oxide or silicon oxynitride, and the thickness of the passivation anti-reflection layer refers to the total thickness of the stack.

[0104] For example, the thickness of the aluminum oxide / silicon nitride stack is 100 nm, wherein the thickness of the aluminum oxide is 5 nm and the thickness of the silicon nitride is 95 nm. The protruding particle size is about 300-400 nm, and the protruding particle height is 150-200 nm.

[0105] According to the embodiments of the present application, the passivation anti-reflection layer is deposited on the doped polysilicon layer, so that the pit structure of the doped polysilicon layer is filled with the passivation layer, and the surface of the passivation layer also has a pit structure. In this way, the surface area of the passivation layer can be increased, and the passivation effect of the passivation layer can be improved. For example, the pit structure of the doped polysilicon layer is filled with the passivation anti-reflection layer such as an aluminum oxide / silicon nitride stack.

[0106] According to embodiments of the present application, the silicon-containing protruding particles include at least one of C element, N element and O element.

[0107] According to embodiments of the present application, the silicon-containing protruding particles doped with the polysilicon layer have C element and / or N element, which can improve the flexibility of the solar cell.

[0108] According to embodiments of the present application, the silicon-containing protruding particles doped with the polysilicon layer have O element, which can improve the conductivity of the polysilicon layer, and thus reduce the contact resistance.

[0109] According to embodiments of the present application, the silicon-containing protruding particles include third main group element and / or fifth main group element, wherein the content of the third main group element and / or the fifth main group element in the silicon-containing protruding particles is greater than the content of the third main group element and / or the fifth main group element in the tunneling oxide layer corresponding to the same doping region, and the content of the third main group element and / or the fifth main group element in the tunneling oxide layer corresponding to the same doping region is greater than the content of the third main group element and / or the fifth main group element in the semiconductor substrate corresponding to the same doping region, so as to further reduce the contact resistance and reduce the recombination of photo-generated carriers in the semiconductor substrate on the basis of forming the tunneling passivation property of the polysilicon layer and the tunneling oxide layer.

[0110] According to embodiments of the present application, the contents of the doped O element, N element, C element, third main group element and / or fifth main group element are all less than the content of the silicon element. By controlling the content of the doped element to be less than the content of the silicon element, the recombination of photo-generated carriers with defects caused by too much doped element can be avoided, and the minority carrier lifetime can be reduced.

[0111] According to embodiments of the present application, the silicon-containing protruding particles contain, for example, Si element, N element, C element, O element and P element, wherein the content of the Si element is 53.11 at.%, the content of the C element is 17.93 at.%, the content of the N element is 22.26 at.%, the content of the O element is 6.3 at.%, and the content of the P element is 0.4 at.%.

[0112] According to embodiments of the present application, by introducing C element, O element and group IIIA / VA element into the silicon-containing protruding particles, the light trapping effect of the silicon-containing protruding particles can be increased, the contact resistance can be reduced, and the photoelectric conversion efficiency of the solar cell can be improved.

[0113] According to embodiments of the present application, the front and back isolation regions 33 of the back contact solar cell have a pyramid structure. The height of the silicon-containing protruding particles is less than the height of the pyramid of the back isolation region 33 of the back contact solar cell, and also less than the height of the pyramid structure of the front of the back contact solar cell.

[0114] According to the embodiments of the present application, the surface of the silicon-containing protruding particles is rough, which can further increase the light trapping effect of the surface of the doped polysilicon layer with the silicon-containing protruding particles, and improve the bifaciality of the cell.

[0115] According to the embodiments of the present application, the solar cell further comprises: a first electrode 10 located on the surface of the first doped polysilicon layer 34 away from the semiconductor substrate 1; and a second electrode 20 located on the surface of the second doped polysilicon layer 35 away from the semiconductor substrate 1.

[0116] According to the embodiments of the present application, the silicon-containing protruding particles are formed on at least a part of the surface of the doped polysilicon layer of the BC solar cell while maintaining the original tower base topography and the grid line geometry. During light incidence, the incident light will refract multiple times between the silicon-containing protruding particles and the tower base, so that more incident light reaches the semiconductor substrate, which can increase the light trapping effect of the back surface of the BC solar cell, and further improve the bifaciality of the BC solar cell. Maintaining the original tower base and grid line features can maintain the passivation and contact effects of the cell, and cooperate with the silicon-containing protruding particles on the surface of the doped polysilicon layer to simultaneously achieve good passivation, contact and light trapping effects of the BC solar cell.

[0117] Referring to FIG. 7, according to the embodiments of the present application, the solar cell can be a bifacial contact solar cell, for example, a TOPCon solar cell.

[0118] According to the embodiments of the present application, the tunneling oxide passivation contact structure composed of the tunneling oxide layer 2 and the doped polysilicon layer 3 can be formed on at least one surface of the semiconductor substrate 1. For example, the tunneling oxide passivation contact structure is formed on one surface or both surfaces of the semiconductor substrate 1; the tunneling oxide passivation contact structure is formed on a local area of at least one surface of the semiconductor substrate 1. That is, the present application is also applicable to a local TOPCon solar cell, a TBC solar cell, or a BC cell with a TOPCon structure in one area, as long as it has a TOPCon structure.

[0119] According to the embodiments of the present application, referring to FIG. 7, the semiconductor substrate 1 has opposite first and second surfaces, and the tunneling oxide passivation contact structure composed of the tunneling oxide layer 2 and the doped polysilicon layer 3 is formed on the second surface of the semiconductor substrate 1.

[0120] According to the embodiments of the present application, the TOPCon solar cell further comprises an emitter 5 and a first passivation layer 6 located on the first surface of the semiconductor substrate 1; and a second passivation layer 7 located on the second surface of the semiconductor substrate 1; wherein the first passivation layer 6 and the second passivation layer 7 achieve the passivation and anti-reflection function.

[0121] According to an embodiment of the present application, the TOPCon solar cell further comprises a third electrode 30 located on the first surface of the semiconductor substrate 1, and a fourth electrode 40 located on the second surface of the semiconductor substrate 1.

[0122] The cleaning removes the electrodes and the passivation layer of the solar cell, and exposes the doped polysilicon layer under the electrodes. As shown in FIG. 8, the surface of the exposed doped polysilicon layer has silicon-containing protruding particles (as shown by the white spots in FIG. 8).

[0123] As shown in FIGS. 8, 9A and 9B, the cleaning removes the electrodes and the passivation layer of the solar cell, and it is observed that the surface of the doped polysilicon layer under the electrodes remains to have silicon-containing protruding particles, and EDS test is performed on any one site of the doped polysilicon layer, and the EDS test result shows that the composition of the silicon-containing protruding particles is silicon.

[0124] According to an exemplary embodiment of the present application, the present application provides a manufacturing method of a solar cell, comprising: operation S01 to operation S03.

[0125] In operation S01, the semiconductor substrate 1 is subjected to polishing treatment to obtain a semiconductor substrate 1 with tower base structures on both the first surface and the second surface.

[0126] According to an embodiment of the present application, the initial silicon wafer after being cut by a diamond wire is subjected to polishing treatment to obtain a semiconductor substrate 1 with tower base structures on both the first surface and the second surface.

[0127] According to an embodiment of the present application, the width of the tower base structure is 5 μm to 50 μm, for example, can be 5 μm, 10 μm, 20 μm, 40 μm, 50 μm, but is not limited to the values mentioned; the height difference between adjacent tower bases is 0.2 μm to 8 μm, for example, can be 0.2 μm, 1 μm, 2 μm, 4 μm, 5 μm, 6 μm, 8 μm, but is not limited to the values mentioned.

[0128] In operation S02, a tunneling oxide layer 2 is deposited on at least one surface of the semiconductor substrate 1.

[0129] According to an embodiment of the present application, the tunneling oxide layer 2 is SiO2 with a thickness of 1 to 5 nm.

[0130] In operation S03, a doped polysilicon layer 3 is deposited on the surface of the tunneling oxide layer 2 away from the semiconductor substrate 1, wherein at least a part of the surface of the doped polysilicon layer 3 away from the tunneling oxide layer 2 has silicon-containing protruding particles.

[0131] According to an embodiment of the present application, the doped polysilicon layer 3 is deposited by a low pressure chemical vapor deposition (LPCVD) method. Specifically, after the tunneling oxide layer 2 is deposited, the semiconductor substrate 1 with the tower structure on the surface is sent into a tube furnace for thin film deposition. Under the conditions of high source amount, high temperature and high pressure, the doped polysilicon layer 3 with the silicon-containing protruding particles on the surface is obtained.

[0132] According to an embodiment of the present application, the silane flow rate is 100-1000 sccm, for example, 100 sccm, 200 sccm, 500 sccm, 800 sccm or 1000 sccm, but is not limited to the values mentioned.

[0133] According to an embodiment of the present application, the deposition temperature of the high-temperature thin film deposition is 500-700°C, for example, 500°C, 550°C, 600°C, 650°C or 700°C, but is not limited to the values mentioned.

[0134] According to an embodiment of the present application, the pressure of the high-pressure thin film deposition is 50-400 mTorr, for example, 50 mTorr, 100 mTorr, 200 mTorr, 300 mTorr or 400 mTorr, but is not limited to the values mentioned.

[0135] According to an embodiment of the present application, when the silane amount is sufficient, the deposition temperature is high and the deposition pressure is large during the thin film deposition, the deposition rate is high, and thus the silane cannot be instantaneously decomposed and reacted, resulting in a decrease in the continuity and uniformity of the thin film deposition and growth, and the silicon-containing particles exist in the doped polysilicon layer after deposition.

[0136] According to an embodiment of the present application, during the deposition of the doped polysilicon layer, the deposition temperature and the silane flow rate of the doped polysilicon layer located close to the edge of the semiconductor substrate are increased, so that the silicon-containing protruding particles exist on the surface of the doped polysilicon layer located close to one corner or one edge of the semiconductor substrate.

[0137] According to an exemplary embodiment of the present application, the present application provides a photovoltaic module comprising the above-mentioned solar cell.

[0138] According to an embodiment of the present application, the silicon-containing protruding particles are formed on at least a part of the surface of the doped polysilicon layer away from the tunneling oxide layer, so as to improve the surface light trapping effect of the solar cell. The solar cell with the improved surface light trapping effect is manufactured to form a photovoltaic module, so as to improve the bifaciality of the photovoltaic module.

[0139] According to embodiments of the present application, at least one surface of the doped polysilicon layer of at least one solar cell in the photovoltaic module has silicon-containing protruding particles on at least a portion of the surface facing away from the tunneling oxide layer.

[0140] According to embodiments of the present application, at least one surface of the doped polysilicon layer of at least one solar cell in the photovoltaic module has silicon-containing protruding particles on at least a portion of the surface facing away from the tunneling oxide layer.

[0141] According to embodiments of the present application, the photovoltaic module includes a solder ribbon adapted to electrically connect two adjacent solar cells, and the solder ribbon has a spacing from the doped polysilicon layer having silicon-containing protruding particles on the second surface of the semiconductor substrate 1.

[0142] According to embodiments of the present application, the solder ribbon can be parallel or perpendicular to the extension direction of the doped polysilicon layer, and the solder ribbon does not block the doped polysilicon layer having silicon-containing protruding particles, and does not affect the improvement of the bifaciality of the solar cell.

[0143] The ordinal numbers used in the specification and claims, such as "first", "second", "third", etc., are used to modify the corresponding elements, and do not imply any ordinal number of the elements, nor represent the order or sequence of manufacturing methods. The ordinal numbers are used only to clearly distinguish an element with a certain name from another element with the same name.

[0144] The above-described specific embodiments further illustrate the purposes, technical solutions, and beneficial effects of the present application. It should be understood that the above-described specific embodiments are merely examples of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A solar cell, characterized by, Comprising: a semiconductor substrate (1); a tunneling oxide layer (2) on at least one surface of the semiconductor substrate (1); a doped polysilicon layer (3) on a surface of the tunneling oxide layer (2) away from the semiconductor substrate (1); wherein at least a portion of the surface of the doped polysilicon layer (3) away from the tunneling oxide layer (2) has silicon-containing protruding particles.

2. The solar cell according to claim 1, wherein: the surface of the doped polysilicon layer (3) at least at a position close to one corner or one edge of the semiconductor substrate (1) has silicon-containing protruding particles.

3. The solar cell according to claim 1, characterized in that, the surface of the doped polysilicon layer (3) away from the tunneling oxide layer (2) further has a plurality of relief structures; the height of the silicon-containing protruding particles is greater than the height of the relief structures.

4. The solar cell according to claim 1, wherein: the doped polysilicon layer (3) comprises a plurality of first doped polysilicon layers (34) and a plurality of second doped polysilicon layers (35) alternately and spacedly arranged along a first direction, wherein one of the first doped polysilicon layers (34) and the second doped polysilicon layers (35) is N-type, and the other of the first doped polysilicon layers (34) and the second doped polysilicon layers (35) is P-type; the surface of the first doped polysilicon layers (34) and / or the second doped polysilicon layers (35) has silicon-containing protruding particles.

5. The solar cell according to claim 4, wherein: the at least one surface of the semiconductor substrate (1) has a non-pyramidal textured structure comprising a plurality of sub-structures, and the doped polysilicon layer on the top surface of the sub-structures has silicon-containing protruding particles; the distribution density of the silicon-containing protruding particles on the N-type doped polysilicon layer on the top surface of the sub-structures is greater than the distribution density of the silicon-containing protruding particles on the P-type doped polysilicon layer on the top surface of the sub-structures.

6. The solar cell of claim 1, wherein the at least one surface of the semiconductor substrate (1) has a non-pyramidal textured structure comprising a plurality of sub-structures, and the doped polysilicon layer on the top surface of the sub-structures has silicon-containing protruding particles; The distribution density of the silicon-containing protruding particles of the doped polysilicon layer on the top surface of at least one of the substructures is 0.1-0.5 / μm 2 .

7. The solar cell according to claim 3, wherein: the number of the protruding particles is less than the number of the relief structures at the same cross-sectional length.

8. The solar cell of claim 1, wherein, Further comprising: a passivation anti-reflection layer on the surface of the doped polysilicon layer (3) away from the semiconductor substrate (1); wherein the height of the silicon-containing protruding particles is greater than the thickness of the passivation anti-reflection layer, and / or the height of the silicon-containing protruding particles is less than 3 times the thickness of the passivation anti-reflection layer.

9. The solar cell of claim 1, wherein, the doped polysilicon layer (3) comprises a plurality of first doped polysilicon layers and a plurality of second doped polysilicon layers alternately and spacedly arranged along a first direction, wherein one of the first doped polysilicon layers and the second doped polysilicon layers is N-type, and the other of the first doped polysilicon layers and the second doped polysilicon layers is P-type; The N-type doped polysilicon layer has a plurality of pit structures on at least a portion of the surface away from the tunneling oxide layer (2), and / or the P-type doped polysilicon layer has a plurality of pit structures on at least a portion of the surface away from the tunneling oxide layer (2).

10. The solar cell of claim 9, wherein, The at least one surface of the semiconductor substrate (1) has a non-pyramidal textured structure, the non-pyramidal textured structure comprises a plurality of sub-structures, and the doped polysilicon layer on the top surface of the sub-structures has a plurality of pit structures, The distribution density of the pit structure on the top surface of the substructure is 50000 / mm2~300000 / mm2 2 .

11. The solar cell of claim 9, wherein, The at least one surface of the semiconductor substrate (1) has a non-pyramidal textured structure, the non-pyramidal textured structure comprises a plurality of sub-structures, The N-type doped polysilicon layer has a plurality of pit structures on at least a portion of the surface away from the tunneling oxide layer (2), and / or the P-type doped polysilicon layer has a plurality of pit structures on at least a portion of the surface away from the tunneling oxide layer (2). The distribution density of the pit structures of the N-type doped polysilicon layer on the top surface of the sub-structures is greater than the distribution density of the pit structures of the P-type doped polysilicon layer on the top surface of the sub-structures.

12. The solar cell of claim 9, wherein, Further comprising: A passivation anti-reflection layer is located on the surface of the doped polysilicon layer (3) away from the semiconductor substrate (1). The pit structures are filled with the passivation anti-reflection layer.

13. The solar cell of claim 1, wherein, The silicon-containing protruding particles comprise at least one of C element, N element and O element.

14. The solar cell according to claim 1 or 13, characterized in that, The silicon-containing protruding particles comprise a third main group element and / or a fifth main group element.

15. The solar cell of claim 1, wherein, The height of the silicon-containing protruding particles ranges from 150 nm to 450 nm. The length of the relief structure in the direction parallel to the surface of the semiconductor substrate (1) ranges from 70 nm to 500 nm. The height of the relief structure ranges from 20 nm to 60 nm.

16. A photovoltaic module, characterized by The solar cell comprises the solar cell as claimed in any one of claims 1 to 15.

17. The photovoltaic module of claim 16, wherein, The photovoltaic module comprises a solder strip, the solder strip is suitable for electrically connecting two adjacent solar cells, In the planar direction of the at least one surface of the semiconductor substrate (1), the solder strip is spaced apart from the doped polysilicon layer (3) having silicon-containing protruding particles.

Images