Solar cell and photovoltaic module

Abstract

The application provides a solar cell and a photovoltaic module, and belongs to the technical field of solar cells. The solar cell comprises a semiconductor substrate, a tunnel oxide layer located on at least one surface of the semiconductor substrate, and a doped polysilicon layer located on a side of the tunnel oxide layer away from the semiconductor substrate, wherein at least a part of a surface of the doped polysilicon layer away from the tunnel oxide layer is provided with silicon-containing protruding particles. The photovoltaic module comprises the above solar cell. The application forms the silicon-containing protruding particles on at least a part of the surface of the doped polysilicon layer away from the tunnel oxide layer, so as to improve the light trapping effect of at least one surface of the solar cell, and further improve the bifaciality of the solar cell.

Description

[0001] This application claims priority to the application with the application date of September 13, 2024, the application number of 202411287736.1, and the invention name of Solar Cell and Photovoltaic Module, the content recorded in the prior application is entirely referred to in this application. TECHNICAL FIELD

[0002] At least one embodiment of the present application relates to a solar cell, in particular to a solar cell and a photovoltaic module. BACKGROUND

[0003] 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, tunnel back contact solar cells (TBC solar cells), or back contact solar cells (BC solar cells) with a TOPCon structure in one area, etc.

[0004] 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 to the formation of good tunneling passivation and contact after the 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, and thus the bifaciality of the solar cell is low. SUMMARY

[0005] Therefore, in order to improve the bifaciality of the solar cell, the present application provides a solar cell and a photovoltaic module.

[0006] According to an embodiment of one aspect 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.

[0007] 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.

[0008] According to an embodiment of the present application, the surface of the doped polysilicon layer away from the tunneling oxide layer also has a plurality of undulating structures; the height of the silicon-containing protruding particles is greater than the height of the undulating structures.

[0009] According to an embodiment of the present application, the doped polysilicon layer comprises a plurality of first doped polysilicon layers and a plurality of second doped polysilicon layers alternately and spacedly arranged 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.

[0010] According to an embodiment of the present application, at least one surface of the semiconductor substrate has a non-pyramidal texture structure, the non-pyramidal texture structure comprises a plurality of sub-structures, the doped polysilicon layer on the top surface of the sub-structure 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-structure 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-structure.

[0011] According to an embodiment of the present application, at least one surface of the semiconductor substrate has a non-pyramidal texture structure, the non-pyramidal texture structure comprises a plurality of sub-structures, the doped polysilicon layer on the top surface of the sub-structure 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 sub-structure is 0.1-0.5 / μm 2 .

[0012] According to an embodiment of the present application, the number of protruding particles is less than the number of undulating structures under the same cross-sectional length.

[0013] According to an embodiment of the present application, the above-mentioned solar cell further comprises:

[0014] A 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.

[0015] In some embodiments, the doped polysilicon layer comprises a plurality of first doped polysilicon layers and a plurality of second doped polysilicon layers alternately and spacedly arranged 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;

[0016] The surface of at least one part of the N-type doped polysilicon layer away from the tunnel oxide layer has a plurality of pit structures, and / or the surface of at least one part of the P-type doped polysilicon layer away from the tunnel oxide layer has a plurality of pit structures.

[0017] 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.

[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,

[0019] a doped polysilicon layer of an 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 tunnel oxide layer, and a doped polysilicon layer of a 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 tunnel oxide layer;

[0020] wherein a distribution density of the pit structures of the doped polysilicon layer of the N type on the top surface of the sub-structures is greater than a distribution density of the pit structures of the doped polysilicon layer of the P type on the top surface of the sub-structures.

[0021] In some embodiments, the solar cell described above further comprises: a passivation anti-reflection layer on a surface of the doped polysilicon layer away from the semiconductor substrate.

[0022] wherein the passivation anti-reflection layer is filled in the pit structures.

[0023] According to embodiments of the present application, the silicon-containing protruding particles comprise at least one of C element, N element and O element.

[0024] 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.

[0025] According to embodiments of the present application, a height of the silicon-containing protruding particles ranges from 150nm to 450nm.

[0026] A length of the relief structure in a direction parallel to the surface of the semiconductor substrate 1 ranges from 70nm to 500nm.

[0027] A height of the relief structure ranges from 20nm to 60nm.

[0028] According to embodiments of another aspect of the present application, a photovoltaic module is provided, comprising the solar cell described above.

[0029] According to embodiments of the present application, the photovoltaic module comprises a solder ribbon, the solder ribbon 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 ribbon has a spacing with the doped polysilicon layer having the silicon-containing protruding particles.

[0030] According to the above embodiments of the present application, the solar cell has silicon-containing protrusions formed on at least a portion of the surface of the doped polycrystalline silicon layer away from the tunnel oxide layer, thereby improving the light trapping effect of at least one surface of the solar cell and thus improving the bifaciality of the solar cell. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings of the embodiments will be briefly described below. Obviously, the drawings described below only relate to some embodiments of this application, and are not intended to limit this application.

[0032] Figure 1 This is a cross-sectional schematic diagram of a back-contact solar cell according to an embodiment of this application;

[0033] Figure 2 This is a scanning electron microscope (SEM) image of the surface of a doped polysilicon layer near the edge of a semiconductor substrate in an embodiment of this application.

[0034] Figure 3 This is another scanning electron microscope (SEM) image of the surface of the doped polysilicon layer near the edge of the semiconductor substrate in an embodiment of this application.

[0035] Figure 4A This is another scanning electron microscope image of the surface of the doped polysilicon layer near the edge of the semiconductor substrate in an embodiment of this application;

[0036] Figure 4B Provided for the embodiments of this application Figure 4A A height measurement diagram of the surface of the doped polycrystalline silicon layer in the image;

[0037] Figure 5 This is another scanning electron microscope image of the surface of the doped polysilicon layer near the edge of the semiconductor substrate in an embodiment of this application;

[0038] Figure 6 A scanning electron microscope image of the surface of a doped polysilicon layer near the edge of a semiconductor substrate in an embodiment of this application;

[0039] Figure 7 This is a cross-sectional schematic diagram of the TOPCon solar cell according to an embodiment of this application;

[0040] Figure 8 This is another scanning electron microscope image of the surface of the doped polysilicon layer near the edge of the semiconductor substrate in an embodiment of this application;

[0041] Figure 9A for Figure 8 Scanning electron microscope images of a portion of the area; and

[0042] Figure 9B for Figure 9Aa plot of EDS test results at one site in the

[0043] BRIEF DESCRIPTION OF DRAWINGS

[0044] 1 - semiconductor substrate;

[0045] 2 - tunnel oxide layer;

[0046] 3 - doped polysilicon layer;

[0047] 31 - minority carrier region;

[0048] 32 - majority carrier region;

[0049] 33 - isolation region;

[0050] 34 - first doped polysilicon layer;

[0051] 35 - second doped polysilicon layer;

[0052] 4 - non-electrode collection region;

[0053] 10 - first electrode;

[0054] 20 - second electrode;

[0055] 5 - emitter;

[0056] 6 - first passivation layer;

[0057] 7 - second passivation layer;

[0058] 30 - third electrode;

[0059] 40 - fourth electrode. DETAILED DESCRIPTION

[0060] To make the purpose, technical solutions and advantages of the present application clearer, the following will further describe the present application with specific examples and with reference to the drawings. However, the present application can be implemented in different forms, and should not be interpreted as limited to the embodiments presented here. On the contrary, these embodiments are presented to make the application thorough and complete, and to fully convey the scope of the present application to those skilled in the art. In the drawings, the size and relative size of the layers and regions can be exaggerated for clarity, and the same reference numerals represent the same elements throughout.

[0061] The terms used herein are merely used to describe specific embodiments, and are not intended to limit the present application. The terms "include", "contain" and the like 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.

[0062] In the related art, the bifaciality of a solar cell is improved from two aspects of tower base optimization and grid line design. From the aspect of tower base optimization, a tower base with finer and greater height difference between adjacent towers is prepared on a semiconductor substrate (silicon substrate) by controlling polishing effect. This method improves light trapping effect on the surface of the cell, but the tower base with finer and greater height difference between adjacent towers is prone to cause the uniformity of the subsequently deposited thin film (tunnel oxide layer and polysilicon layer) to decrease, and further cause tunneling, passivation and contact problems. From the aspect of grid line design, the width of the main grid and the auxiliary grid is narrowed. This method can improve light absorption, but the increase of the aspect ratio of the grid line puts forward more requirements for the formability of the paste. Meanwhile, the finer grid line also increases the contact resistance of the cell.

[0063] Therefore, it is necessary to provide a solar cell and a photovoltaic module to solve the technical problem of the related art that the bifaciality of a solar cell needs to be improved.

[0064] Figure 1 A cross-sectional schematic diagram of a back contact solar cell is provided.

[0065] According to an example embodiment of the present application, the present application provides a solar cell, as shown in Figure 1 or Figure 5 The solar cell comprises:

[0066] a semiconductor substrate 1;

[0067] a tunnel oxide layer 2 located on at least one surface of the semiconductor substrate 1;

[0068] a doped polysilicon layer 3 located on a side of the tunnel 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 tunnel oxide layer 2 has silicon-containing protruding particles.

[0069] According to an example embodiment of the present application, as shown in Figure 1 The solar cell is a back contact solar cell. The semiconductor substrate 1 has opposite first and second surfaces, and the tunnel oxide layer 2 is located on the second surface of the semiconductor substrate 1, which is the back surface of the back contact solar cell in this embodiment.

[0070] In some embodiments, the surface of the doped polysilicon layer 3 away from the tunnel oxide layer 2 also has a plurality of relief structures; the height of the silicon-containing protruding particles is greater than the height of the relief structures.

[0071] In some embodiments, the surface of the doped polysilicon layer 3 away from the tunnel oxide layer 2 also has a plurality of relief structures; the width of the silicon-containing protruding particles is less than the width of the relief structures.

[0072] According to the embodiments of the present application, the relief structure can be a silicon grain for example. The length of the relief structure 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, 500 nm. The height of the relief structure is 20-60 nm, for example 20 nm, 30 nm, 40 nm, 50 nm, 60 nm.

[0073] According to the embodiments 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, the height of the relief structure is usually small, that is, the relief degree of the relief structure is too slow, it is difficult to improve the light trapping effect through the relief structure, and the contribution of the relief structure to the double-sided rate of the cell is limited.

[0074] According to the embodiments 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, the width of the relief structure is usually wide, that is, the relief degree of the relief structure is too slow, it is difficult to improve the light trapping effect through the relief structure, and the contribution of the relief structure to the double-sided rate of the cell is limited. The present application improves the light trapping effect of the doped polysilicon layer and the double-sided rate of the cell through the silicon-containing protruding particles with higher height and / or narrower width, while not damaging the tunneling passivation effect of the doped polysilicon layer and improving the photoelectric conversion effect of the cell.

[0075] Reference is made to Figure 3 The black dots shown and Figure 6 The white particles shown represent silicon-containing protruding particles. The silicon-containing protruding particles have a partial spherical structure, such as a hemispherical structure; the height (approximately the radius) of the silicon-containing protruding particles is 150-450 nm, for example, can be 150 nm, 200 nm, 300 nm, 400 nm, 450 nm, but is not limited to the values given.

[0076] According to the embodiments of the present application, the height of the silicon-containing protruding particles is 150-450 nm, which can achieve 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 on the silicon-containing protruding particles and the tower base sidewall, and it is difficult to achieve light trapping effect. If the silicon-containing protruding particles are too large, the film quality of the doped polysilicon will be reduced, which is not conducive to the photoelectric conversion efficiency of the cell.

[0077] 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 Figure 4B The surface of the doped polysilicon layer has two high protrusions Figure 4B The arrow in points to the area Figure 4A The two silicon-containing protruding particles on the surface of the doped polysilicon layer in Figure 4AThe two black dots pointed by the arrows in FIG. 6B indicate the silicon-containing protruding particles. It is shown that the surface of the doped polysilicon layer away from the tunnel oxide layer has silicon-containing protruding particles. Referring to Figure 6 The white dots shown in FIG. 6B are 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 through the silicon-containing protruding particles, and more sunlight is incident on the semiconductor substrate 1, increasing the light trapping effect of the at least one surface of the solar cell, thereby improving the bifaciality of the solar cell.

[0078] According to 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.

[0079] According to 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 given.

[0080] Referring to Figure 2 As shown in FIG. 6B, the second surface of the semiconductor substrate 1 has a non-pyramidal textured structure, and the non-pyramidal textured structure includes a plurality of substructures (such as Figure 2 The tunnel 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 (such as Figure 2 The black dots shown in FIG. 6B indicate the silicon-containing protruding particles).

[0081] It should be noted that since the silicon-containing protruding particles can cause the refractive index of the incident light to change, too many silicon-containing protruding particles on too large an area can cause color difference problems of the cell. Specifically, the silicon-containing protruding particles cause the roughness of the surface of the doped polysilicon layer to be greater, causing the doped polysilicon layer to reflect light of different wavelengths differently, resulting in color difference problems of the cell. Therefore, by controlling the silicon-containing protruding particles to be within a suitable range (the silicon-containing protruding particles are within 3 mm from the edge of the semiconductor substrate 1), the light trapping effect of the surface of the cell can be increased, the bifaciality of the cell can be improved, and the process kick-off and appearance defect problems of the final cell product caused by the color difference problem can be avoided.

[0082] According to embodiments of the present application, referring to Figure 1 As shown in FIG. 6B, 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 has an isolation region 33 between the minority carrier regions 31 and the majority carrier regions 32.

[0083] According to an embodiment of the present application, the doped polysilicon layer 3 comprises 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 minority carriers is arranged in the minority carrier region 31; the second doped polysilicon layer 35 for collecting and leading out majority carriers 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 is P-type. For example, the first doped polysilicon layer 34 can be N-type, and the second doped polysilicon layer 35 can be P-type; or the first doped polysilicon layer 34 can be P-type, and the second doped polysilicon layer 35 can be N-type.

[0084] 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 that of the second doped polysilicon layer 35.

[0085] 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.

[0086] 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.

[0087] According to an embodiment of the present application, the surface of the first doped polysilicon layer 34 has silicon-containing protruding particles.

[0088] According to an embodiment of the present application, the surface of the second doped polysilicon layer 35 has silicon-containing protruding particles.

[0089] According to an embodiment of the present application, the surface of the first doped polysilicon layer 34 and the second doped polysilicon layer 35 both have silicon-containing protruding particles.

[0090] In some embodiments, the N-type doped polysilicon layer has a plurality of protruding structures on at least a part of the surface away from the tunnel oxide layer, the protruding structures can increase the effective light absorption of the N-type doped polysilicon layer and 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. In addition, the P-type doped polysilicon layer does not have protruding structures on the surface away from the tunnel oxide layer, and the surface of the P-type doped polysilicon layer is smoother, which is conducive to achieving better tunnel passivation effect.

[0091] In some embodiments, the surface of the N-type doped polysilicon layer can not have the protruding structure, and the surface of the P-type doped polysilicon layer away from the tunnel oxide layer 2 has the plurality of protruding structures, according to the actual performance requirements of the solar cell. For the N-type substrate, the P-type doped polysilicon layer serves as an emitter region, and the surface of the P-type doped polysilicon layer has the 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.

[0092] According to the embodiments of the present application, the surface of the at least two first doped polysilicon layers 34 has the silicon-containing protruding particles.

[0093] According to the embodiments of the present application, the surface of the at least two second doped polysilicon layers 35 has the silicon-containing protruding particles.

[0094] According to the embodiments of the present application, the surface of the first doped polysilicon layer 34 and / or the second doped polysilicon layer 35 has the silicon-containing protruding particles, and the incident light is refracted multiple times in the silicon-containing protruding particles, so that more light is incident on the surface of the semiconductor substrate 1. Therefore, the more the doped polysilicon layers having the silicon-containing protruding particles, the more the light trapping effect of the second surface of the cell is increased, and the bifaciality of the cell is improved.

[0095] According to the 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 the silicon-containing protruding particles, and 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.

[0096] 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 the doping concentration 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 the distribution density of the silicon-containing protruding particles on the P-type doped polysilicon layer, the light trapping effect of the N-type region is increased, the loss of Auger recombination of the N-type region is compensated, the difference between the light trapping effects of the N-type region and the P-type region is reduced, the number of collected carriers of the N-type region is increased, and the photoelectric conversion efficiency of the back contact solar cell is improved.

[0097] According to the 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 the silicon-containing protruding particles, and the distribution density of the silicon-containing protruding particles on the doped polysilicon layer on the top surface of the at least one substructure is 0.1-0.5 / μm 2For example, it can be 0.1 / μm 2 0.2 / μm 2 0.3 / μm 2 0.4 / μm 2 0.5 / μm 2 but not limited to the values given. The top surface refers to the complete polygonal or complete arc structure that can be observed in the top view of the battery product, which corresponds to the surface of the silicon substrate that is recessed towards the interior of the silicon substrate.

[0098] According to the embodiments of the present application, the distribution number of the convex particles is less than the distribution number of the relief structure under the same cross-sectional length. For example, referring to FIG. 2A and FIG. 2B, under the same magnification and the same window length, the distribution number of the relief structure is greater than the distribution number of the silicon-containing convex particles. Figure 5

[0099] 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-pyramid texture structure can be distributed with silicon-containing convex 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 convex particles.

[0100] According to the embodiments of the present application, the back surface of the solar cell has the tower base structure and the silicon-containing convex particles. The incident sunlight will refract multiple times at the silicon-containing convex particles and the tower base sidewall, so that more sunlight is incident on the surface of the semiconductor substrate. Therefore, the doped polysilicon layer with more dense silicon convex particles can further increase the light trapping effect of the back surface of the battery and improve the bifaciality of the solar cell.

[0101] In some embodiments, at least a part of the surface of the doped polysilicon layer 3 away from the tunnel oxide layer 2 has a plurality of pit structures, which can improve the light trapping effect of at least one surface of the solar cell, thereby improving the bifaciality of the solar cell.

[0102] In some embodiments, at least a part of the surface of the doped polysilicon layer 3 away from the tunnel oxide layer 2 has a plurality of pit structures, which can improve the light trapping effect of at least one surface of the solar cell, thereby improving the bifaciality of the solar cell.

[0103] ​In some embodiments, the depth of the pit structure is 80-150 nm, for example, can be 80 nm, 100 nm, 120 nm, 130 nm, 150 nm, but is not limited to the values mentioned.

[0104] In some embodiments, the reference Figure 5 As shown, the surface of the doped polysilicon layer close to the edge of the semiconductor substrate has a dot or line pit structure, wherein the depth of the pit structure is less than the thickness of the doped polysilicon layer.

[0105] In some embodiments, the length of the pit structure in the direction parallel to the surface of the semiconductor substrate 1 is 150-630 nm, for example, can be 150 nm, 200 nm, 300 nm, 500 nm, 630 nm, but is not limited to the values mentioned.

[0106] 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, 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), further improving the light trapping effect and improving the bifaciality.

[0107] In some embodiments, the N-type doped polysilicon layer has a plurality of pit structures on at least a part of the surface away from the tunnel oxide layer 2; wherein the depth of the pit structure is greater than the height of the relief structure. And the P-type doped polysilicon layer has no pit structure on the surface away from the tunnel oxide layer 2.

[0108] 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 tunnel oxide layer, which can increase the effective light absorption of the N-type doped polysilicon layer and improve the bifaciality of the solar cell; and the pit structure can increase the contact area of the N-type doped polysilicon layer and the metal electrode, which is beneficial to reduce the contact resistance. And the P-type doped polysilicon layer has no pit structure on the surface away from the tunnel oxide layer, the surface of the P-type doped polysilicon layer is smoother, which is beneficial to achieve better tunnel passivation effect.

[0109] For ease of characterization, the present application selects the top surface of the substructure of the non-pyramid texture structure to quantify the distribution density of the pit structure.

[0110] In some embodiments, the distribution density of the pit structure on the top surface of the substructure is 50000 / mm2~300000 / mm2, 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 the distribution density of the pit structure is too large, which can reduce the tunneling passivation effect of the passivation contact structure (the passivation contact structure includes the tunneling oxide layer and the doped polysilicon layer); the distribution density of the pit structure is too small, which cannot achieve sufficient light trapping effect. The pit structure with the specific distribution density of the present application can achieve light trapping effect while not significantly reducing the tunneling passivation effect of the passivation contact structure.

[0111] 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 a pit structure; 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.

[0112] According to the embodiments of the present application, for the N-type substrate, the P-type doped polysilicon layer acts 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.

[0113] 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 surface of the N-type doped polysilicon layer on the top surface of the substructure has a plurality of pit structures, and at least a part of the surface of the P-type doped polysilicon layer on the top surface of the substructure has a plurality of pit structures; 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.

[0114] In the embodiments of the present application, generally, the doping concentration of the N-type region doped polysilicon layer is higher than the doping concentration of the P-type region doped polysilicon layer, and the N-type region can 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 the distribution density of the pit structure 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, which is beneficial to increasing the number of carrier collection of the N-type region, and further improving the photoelectric conversion efficiency of the back contact solar cell.

[0115] In some embodiments, the solar cell described above further comprises: a passivation anti-reflective 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-reflective layer, and / or the height of the silicon-containing protruding particles is less than 3 times the thickness of the passivation anti-reflective layer.

[0116] According to the embodiments of the present application, after depositing the passivation anti-reflective layer on the doped polysilicon layer 3, due to the presence of the silicon-containing protruding particles on at least part of the surface of the doped polysilicon layer 3 away from the tunnel oxide layer 2, at least part of the surface of the deposited passivation anti-reflective layer will also form protruding particles.

[0117] 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-reflective layer, further increases the area of the passivation anti-reflective layer, and improves light absorption; further, the height of the protruding particles is less than 3 times the thickness of the passivation anti-reflective layer, so that the protruding particles are not too high, and too high will affect the film uniformity of the passivation anti-reflective layer and reduce the passivation effect.

[0118] According to the embodiments of the present application, the passivation anti-reflective layer comprises an aluminum oxide and one or more of silicon nitride, silicon oxide or silicon oxynitride, and the thickness of the passivation anti-reflective layer refers to the total thickness of the stack.

[0119] 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.

[0120] According to the embodiments of the present application, the passivation anti-reflective layer is deposited on the doped polysilicon layer, so that the recess structure of the doped polysilicon layer is filled with the passivation layer, and the surface of the passivation layer also has a recess structure, which can increase the surface area of the passivation layer and further improve the passivation effect of the passivation layer. For example, the recess structure of the doped polysilicon layer is filled with the passivation anti-reflective layer such as an aluminum oxide / silicon nitride stack.

[0121] According to the embodiments of the present application, the silicon-containing protruding particles of the doped polysilicon layer comprise at least one of C element, N element and O element.

[0122] According to the embodiments of the present application, the silicon-containing protruding particles of the doped polysilicon layer have C element and / or N element, which can improve the flexibility of the solar cell.

[0123] According to the embodiments of the present application, the silicon-containing protruding particles of the doped polysilicon layer have O element, which can improve the conductivity of the doped polysilicon layer and further reduce the contact resistance.

[0124] According to the embodiments of the present application, the silicon-containing convex particles include the third main group element and / or the fifth main group element, wherein the content of the third main group element and / or the fifth main group element in the silicon-containing convex 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 on the basis of forming the tunneling passivation property of the doped polysilicon layer and the tunneling oxide layer, reduce the recombination of the photo-generated carriers in the semiconductor substrate.

[0125] According to the 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 the photo-generated carriers with the defects caused by too much doped element can be avoided, and the minority carrier lifetime can be reduced.

[0126] According to the embodiments of the present application, the silicon-containing convex particles, for example, contain 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.%.

[0127] According to the embodiments of the present application, by introducing the C element, O element and ⅢA / ⅤA group element into the silicon-containing convex particles, the light trapping effect of the silicon-containing convex particles can be increased, and the contact resistance can be reduced, and the photoelectric conversion efficiency of the solar cell can be improved.

[0128] According to the 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 convex particles is less than the height of the pyramid of the back isolation region 33 of the back contact solar cell, and is also less than the height of the pyramid structure of the front of the back contact solar cell.

[0129] According to the embodiments of the present application, the surface of the silicon-containing convex particles is rough, which can further increase the light trapping effect of the surface of the doped polysilicon layer with the silicon-containing convex particles, and improve the double-sided rate of the cell.

[0130] According to the embodiments of the present application, the solar cell described above further includes 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.

[0131] According to the embodiments of the present application, the silicon-containing protruding particles are formed on at least part of the surface of the doped polysilicon layer of the BC solar cell while keeping 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, thereby improving the bifaciality of the BC solar cell. Keeping 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.

[0132] Referring to Figure 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.

[0133] 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, etc., as long as it has a TOPCon structure.

[0134] According to the embodiments of the present application, referring to Figure 7 As shown in the figure, 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.

[0135] 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 realize the passivation and anti-reflection function.

[0136] According to the embodiments 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.

[0137] The electrodes and passivation layers of the solar cell are cleaned to expose the doped polysilicon layer under the electrodes. Referring to Figure 8 As shown in the figure, the surface of the exposed doped polysilicon layer has silicon-containing protruding particles (as indicated by the white dots in Figure 8 ).

[0138] Reference Figure 8 、 Figures 9A-9B As shown in FIG. 2, the cleaning removes the electrode and the passivation layer of the solar cell, and it is observed that the surface of the doped polysilicon layer under the electrode remains silicon-containing protruding particles. EDS test is performed on any site of the doped polysilicon layer, and the EDS test result shows that the composition of the silicon-containing protruding particles is silicon.

[0139] According to an exemplary embodiment of the present application, the present application provides a manufacturing method of a solar cell, comprising operations S01-S03.

[0140] In operation S01, a polishing process is performed on the semiconductor substrate 1 to obtain a semiconductor substrate 1 with a tower base structure on both the first surface and the second surface.

[0141] According to an embodiment of the present application, the initial silicon wafer cut by the diamond wire is polished to obtain a semiconductor substrate 1 with a tower base structure on both the first surface and the second surface.

[0142] According to an embodiment of the present application, the width of the tower base structure is 5-50 μm, for example, 5 μm, 10 μm, 20 μm, 40 μm, or 50 μm, but is not limited to the values mentioned above; the height difference between adjacent tower bases is 0.2-8 μm, for example, 0.2 μm, 1 μm, 2 μm, 4 μm, 5 μm, 6 μm, or 8 μm, but is not limited to the values mentioned above.

[0143] In operation S02, a tunnel oxide layer 2 is deposited on at least one surface of the semiconductor substrate 1.

[0144] According to an embodiment of the present application, the tunnel oxide layer 2 is SiO2with a thickness of 1-5 nm.

[0145] In operation S03, a doped polysilicon layer 3 is deposited on the surface of the tunnel oxide layer 2 away from the semiconductor substrate 1, wherein the doped polysilicon layer 3 has silicon-containing protruding particles on at least a part of the surface thereof away from the tunnel oxide layer 2.

[0146] 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 deposition of the tunnel oxide layer 2, the semiconductor substrate 1 with the tower base structure on the surface is sent into a tube furnace for thin film deposition, and 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.

[0147] 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, 1000 sccm, but is not limited to the values mentioned.

[0148] According to an embodiment of the present application, the deposition temperature of the high-temperature thin film deposition is 500-700℃, for example, 500℃, 550℃, 600℃, 650℃, 700℃, but is not limited to the values mentioned.

[0149] 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, 400 mTorr, but is not limited to the values mentioned.

[0150] According to an embodiment of the present application, when the amount of silane is sufficient, the deposition temperature is high, and the deposition pressure is large during the thin film deposition process, the deposition rate is high, so that 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 silicon-containing particles exist in the doped polysilicon layer after deposition.

[0151] 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 near the edge of the semiconductor substrate are increased, so that silicon-containing protruding particles are formed on the surface of the doped polysilicon layer located near one corner and one side of the semiconductor substrate.

[0152] According to an exemplary embodiment of the present application, the present application provides a photovoltaic module comprising the above-mentioned solar cell.

[0153] According to an embodiment of the present application, by forming silicon-containing protruding particles on at least a part of the surface of the doped polysilicon layer away from the tunnel oxide layer, the surface light trapping effect of the solar cell is improved. The solar cell with improved surface light trapping effect is manufactured to form a photovoltaic module, so as to improve the bifaciality of the photovoltaic module.

[0154] According to an embodiment of the present application, at least a part of the surface of the doped polysilicon layer of at least one solar cell in the photovoltaic module away from the tunnel oxide layer has silicon-containing protruding particles.

[0155] According to an embodiment of the present application, at least a part of the surface of the doped polysilicon layer of at least two solar cells in the photovoltaic module away from the tunnel oxide layer has silicon-containing protruding particles.

[0156] According to the 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 the solder strip has a spacing with the doped polysilicon layer with silicon-containing protruding particles on the second surface of the semiconductor substrate 1.

[0157] According to the embodiments of the present application, the solder strip can be parallel or perpendicular to the extension direction of the doped polysilicon layer, the solder strip does not shield the doped polysilicon layer with silicon-containing protruding particles, and does not affect the improvement of the bifaciality of the solar cell.

[0158] 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 mean that the elements have any ordinal number, nor represent the order of one element and another element, or the order of the manufacturing method. The use of these ordinal numbers is only used to clearly distinguish an element with a certain name from another element with the same name.

[0159] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only for specific embodiments of the present application and is 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 in that, include: Semiconductor substrate (1); A through oxide layer (2) is located on at least one surface of the semiconductor substrate (1), the at least one surface including the back side of the solar cell; A doped polycrystalline silicon layer (3) is located on the side of the tunnel oxide layer (2) away from the semiconductor substrate (1); A passivation antireflection layer is located on the surface of the doped polysilicon layer (3) away from the semiconductor substrate (1); Wherein, at least a portion of the surface of the doped polycrystalline silicon layer (3) away from the tunnel oxide layer (2) has silicon-containing protrusion particles; The height of the silicon-containing protrusions is greater than the thickness of the passivation antireflection layer, and / or the height of the silicon-containing protrusions is less than three times the thickness of the passivation antireflection layer.

2. The solar cell according to claim 1, characterized in that, The surface of the doped polysilicon layer (3) located at least near a corner or an edge of the semiconductor substrate (1) has silicon-containing protrusions.

3. The solar cell according to claim 1, characterized in that, The surface of the doped polycrystalline silicon layer (3) away from the tunnel oxide layer (2) also has multiple undulating structures; The height of the silicon-containing protrusion particles is greater than the height of the undulating structure.

4. The solar cell according to claim 1, characterized in that, The doped polysilicon layer (3) includes a plurality of first doped polysilicon layers (34) and a plurality of second doped polysilicon layers (35) that are alternately distributed along a first direction, wherein 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; The surfaces of the first doped polysilicon layer (34) and / or the second doped polysilicon layer (35) have silicon-containing protrusions.

5. The solar cell according to claim 4, characterized in that, The semiconductor substrate (1) has at least one surface with a non-pyramid texture structure, the non-pyramid texture structure comprising a plurality of substructures, and the doped polysilicon layer on the top surface of the substructure having silicon-containing protrusion particles. The distribution density of silicon-containing protrusions on the N-type doped polysilicon layer on the top surface of the substructure is greater than the distribution density of silicon-containing protrusions on the P-type doped polysilicon layer on the top surface of the substructure.

6. The solar cell according to claim 1, characterized in that, The semiconductor substrate (1) has at least one surface with a non-pyramid texture structure, the non-pyramid texture structure comprising a plurality of substructures, and the doped polysilicon layer on the top surface of the substructure having silicon-containing protrusion particles. The distribution density of silicon-containing protrusions in the top surface of at least one of the substructures is 0.1~0.5 particles / μm. 2 .

7. The solar cell according to claim 3, characterized in that, For the same cross-sectional length, the number of protruding particles is less than the number of undulating structures.

8. The solar cell according to claim 1, characterized in that, The doped polysilicon layer (3) includes a plurality of first doped polysilicon layers and a plurality of second doped polysilicon layers that are alternately distributed 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 layer and the second doped polysilicon layer is P-type. The N-type doped polysilicon layer has a plurality of pit structures on at least a portion of its 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 its surface away from the tunneling oxide layer (2).

9. The solar cell according to claim 8, characterized in that, The semiconductor substrate (1) has at least one surface with a non-pyramid texture structure, the non-pyramid texture structure comprising multiple substructures, and the doped polysilicon layer on the top surface of the substructure having multiple pit structures. The distribution density of the pit structure on the top surface of the substructure is 50,000 / mm² to 300,000 / mm².

10. The solar cell according to claim 8, characterized in that, The semiconductor substrate (1) has at least one surface with a non-pyramid texture structure, the non-pyramid texture structure comprising multiple substructures. At least a portion of the N-type doped polysilicon layer on the top surface of the substructure has a plurality of pit structures on the surface away from the tunnel oxide layer (2), and at least a portion of the P-type doped polysilicon layer on the top surface of the substructure has a plurality of pit structures on the surface away from the tunnel oxide layer (2). 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.

11. The solar cell according to claim 8, characterized in that, Also includes: A passivation antireflection layer is located on the surface of the doped polysilicon layer (3) away from the semiconductor substrate (1); The recessed structure is filled with the passivation and antireflection layer.

12. The solar cell according to claim 1, characterized in that, The silicon-containing protrusions include at least one of the elements C, N, and O.

13. The solar cell according to claim 1 or 12, characterized in that, The silicon-containing protrusions include Group 3 elements and / or Group 5 elements.

14. The solar cell according to claim 3, characterized in that, The height range of the silicon-containing protrusion particles is 150nm~450nm; The length of the undulating structure in the direction parallel to the surface of the semiconductor substrate (1) is 70 nm to 500 nm; The height of the undulating structure is 5nm~60nm.

15. A photovoltaic module, characterized in that, Including the solar cell as described in any one of claims 1 to 14.

16. The photovoltaic module according to claim 15, characterized in that, The photovoltaic module includes solder strips suitable for electrically connecting two adjacent solar cells. In the planar direction of at least one surface of the semiconductor substrate (1), the solder strip is spaced from the doped polysilicon layer (3) having silicon-containing protrusion particles.

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