Solar cells, photovoltaic modules and photovoltaic systems

Abstract

The application provides a solar cell, a photovoltaic module and a photovoltaic system. The solar cell comprises: a silicon substrate; a passivation layer arranged on the surface of the silicon substrate; and a polycrystalline silicon doped layer arranged on the passivation layer. In the embodiment of the application, the first passivation layer is arranged on the surface of the second side of the silicon substrate, and the second passivation layer is arranged on the surface of the second side of the silicon substrate, so that the two sides of the silicon substrate are directly in contact with the passivation layer, in other words, no inner expansion layer is arranged between the silicon substrate and the passivation layer. In particular for the first side of the silicon substrate, when the P-type polycrystalline silicon doped layer is expanded, the inner expansion layer is formed, and the doped atoms in the inner expansion layer form a recombination center on the surface of the first side of the silicon substrate, thereby attracting carrier recombination, and further affecting the tunneling efficiency of the carrier. In the embodiment, the surface of the first side of the silicon substrate is directly in contact with the first passivation layer, so that the effect of the inner expansion layer on the passivation effect of the passivation layer can be avoided, and the tunneling efficiency of the carrier is improved.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a solar cell, a photovoltaic module, and a photovoltaic system. Background Technology

[0002] Solar cells, as a sustainable and clean energy technology, are based on the photovoltaic effect of semiconductor PN junctions to directly convert solar energy into electrical energy, and conversion efficiency is a key indicator for measuring battery performance.

[0003] In some solar cells, a passivation layer (also known as a "tunneling oxide layer") is used to isolate the doped polycrystalline silicon from the silicon substrate, thereby achieving both efficient carrier tunneling and surface passivation. However, to ensure efficient carrier tunneling and reduce series resistance, the passivation layer needs to be extremely thin (typically 1-2 nm) to maintain a low tunneling resistance. During the subsequent high-temperature diffusion of the polycrystalline silicon dopant layer, the passivation layer can form a "pinhole" structure, causing the dopant elements to diffuse inward to the silicon substrate surface, forming an inward diffusion layer, which reduces the passivation effect. Summary of the Invention

[0004] The present invention aims to at least solve the problem in the prior art where an inner expansion layer is formed between the passivation layer and the silicon substrate, affecting the passivation effect, and proposes a solar cell, a photovoltaic module, and a photovoltaic system.

[0005] To achieve the objectives of this invention, a solar cell is provided, comprising: a silicon substrate; a passivation layer disposed on the surface of the silicon substrate; and a polycrystalline silicon doped layer disposed on the passivation layer.

[0006] In some embodiments, the silicon substrate includes a first side and a second side disposed opposite to each other; the passivation layer includes a first passivation layer disposed on the surface of the first side of the silicon substrate; the polysilicon doped layer includes a P-type polysilicon doped layer disposed on the first passivation layer.

[0007] In some embodiments, the first passivation layer includes: a first portion having a first porous structure, the first portion being located between the silicon substrate and the P-type polysilicon doped layer; and a second portion superimposed on the first portion, the second portion being located between the first portion and the silicon substrate.

[0008] In some embodiments, monocrystalline silicon is disposed in the pores of the first porous structure.

[0009] In some embodiments, the ratio of the number of pores in the first porous structure to the area of ​​the first portion ranges from 1×10. 6 holes / cm 2 ~1×10 10 holes / cm2 .

[0010] In some embodiments, the first porous structure includes: a plurality of pore groups, the plurality of pore groups being spaced apart along a first direction, each pore group having a plurality of pores, the pores in the same group being spaced apart along a second direction, the first direction and the second direction being parallel to a first side surface of the silicon substrate, and the first direction intersecting the second direction.

[0011] In some embodiments, within the same group of pores, the pore density ranges from 1×10⁻⁶. 6 holes / cm ~1×10 10 holes / cm, wherein the hole density is the ratio of the number of holes to the unit length of the first portion in the first direction.

[0012] In some embodiments, within the same group of pores, there are multiple regions spaced equidistant from each other along the first direction, and the average value of the pore density within the multiple regions ranges from 1 × 10⁻⁶. 6 holes / cm ~1×10 10 holes / cm.

[0013] In some embodiments, within the same group of pores, the ratio of the standard deviation of the pore density to the average range of the pore density in the plurality of regions is 1 × 10⁻⁶. -4 ~1×10 -2 .

[0014] In some embodiments, the average pore density of the plurality of pore groups ranges from 1 × 10⁻⁶. 6 holes / cm ~1×10 10 holes / cm.

[0015] In some embodiments, the ratio of the standard deviation of the pore density of the plurality of pore groups to the average range of the pore density is 1 × 10⁻⁶. -4 ~1×10 -2 .

[0016] In some embodiments, the second portion has a second porous structure, the average pore size of the second porous structure being smaller than the average pore size of the first porous structure.

[0017] In some embodiments, the ratio of the number of pores in the second porous structure to the area of ​​the second portion is less than the ratio of the number of pores in the first porous structure to the area of ​​the first portion.

[0018] In some embodiments, the doping concentration of the first portion is greater than the doping concentration of the second portion.

[0019] In some embodiments, the doping concentration is higher at locations on the first passivation layer that are farther away from the silicon substrate.

[0020] In some embodiments, the doping concentration of the first passivation layer varies with a rate of change of ΔX1, 2.5 × 10⁻⁶ along its thickness direction. 24 atom / cm 4 ≤△X1≤1.5×10 26 atom / cm 4 .

[0021] In some embodiments, the rate of change of doping concentration ΔX of the first passivation layer in its thickness direction is obtained according to the following formula:

[0022] △X1=(X MAX -X MIN ) / D;

[0023] Among them, X MAX X represents the maximum doping concentration in the first passivation layer. MIN denoted as the minimum doping concentration in the first passivation layer, and D as the thickness of the first passivation layer.

[0024] In some embodiments, the thickness D of the first passivation layer ranges from 1.5 nm to 4.0 nm.

[0025] In some embodiments, the thickness D2 of the second portion ranges from 1.2 nm to 2.4 nm.

[0026] In some embodiments, the oxygen-to-silicon ratio in the first passivation layer ranges from 1.5 to 2.0.

[0027] In some embodiments, the doping concentration of the P-type polysilicon doped layer ranges from 1.0 × 10⁻⁶. 19 atom / cm 3 ~1.5×10 20 atom / cm 3 .

[0028] In some embodiments, the P-type polycrystalline silicon doped layer includes boron atoms and / or gallium atoms.

[0029] In some embodiments, the doping concentration on the side of the silicon substrate that contacts the first passivation layer is less than the doping concentration of the P-type polycrystalline silicon doped layer.

[0030] In some embodiments, the doping concentration on the side of the silicon substrate that contacts the passivation layer ranges from 1.5 × 10⁻⁶. 14 atom / cm 3 ~1.5×10 17 atom / cm3 .

[0031] In some embodiments, the silicon substrate includes a first side and a second side disposed opposite to each other; the passivation layer includes a second passivation layer disposed on the surface of the second side of the silicon substrate; the polysilicon doped layer includes a first N-type polysilicon doped layer disposed on the second passivation layer.

[0032] In some embodiments, the thickness of the second passivation layer ranges from 0.5 nm to 1.5 nm.

[0033] In some embodiments, the doping concentration of the second passivation layer varies with a rate of change of ΔX² in its thickness direction, which is 2.5 × 10⁻⁶. 25 atom / cm 4 ≤△X2≤1.5×10 27 atom / cm 4 .

[0034] In some embodiments, the oxygen-to-silicon ratio in the second passivation layer ranges from 1.5 to 2.0.

[0035] In some embodiments, the doping concentration of the first N-type polysilicon doped layer ranges from 1.0 × 10⁻⁶. 20 atom / cm 3 ~1.5×10 21 atom / cm 3 .

[0036] In some embodiments, the first N-type polysilicon doped layer includes phosphorus atoms.

[0037] In some embodiments, the doping concentration on the side of the silicon substrate that contacts the second passivation layer is less than the doping concentration of the first N-type polysilicon doped layer.

[0038] In some embodiments, the doping concentration on the side of the silicon substrate that contacts the second passivation layer ranges from 1.5 × 10⁻⁶. 14 atom / cm 3 ~1.5×10 17 atom / cm 3 .

[0039] In some embodiments, the passivation layer further includes: a third passivation layer disposed on the surface of the first N-type polysilicon doped layer on the side opposite to the silicon substrate;

[0040] The polysilicon doped layer further includes a second N-type polysilicon doped layer disposed on the third passivation layer.

[0041] In some embodiments, the silicon substrate includes a first side and a second side disposed opposite to each other; the polysilicon doped layer includes: a first N-type polysilicon doped layer and a second N-type polysilicon doped layer, the first N-type polysilicon doped layer being disposed on the second side surface of the silicon substrate, and the second N-type polysilicon doped layer being disposed on the first side of the first N-type polysilicon doped layer away from the silicon substrate; the passivation layer includes: a second passivation layer disposed between the first N-type polysilicon doped layer and the second N-type polysilicon doped layer, the second passivation layer having a third porous structure, the third porous structure being filled with polysilicon, and the polysilicon within the third porous structure connecting the first N-type polysilicon doped layer and the second N-type polysilicon doped layer.

[0042] According to a second aspect of the present invention, a photovoltaic module comprising the aforementioned solar cell is also disclosed.

[0043] According to a third aspect of the present invention, a photovoltaic system comprising the photovoltaic module described above is also disclosed.

[0044] In embodiments of the present invention, by disposing of a first passivation layer on the surface of the second side of the silicon substrate and a second passivation layer on the surface of the second side of the silicon substrate, the two sides of the silicon substrate are in direct contact with the passivation layer. In other words, no inner expansion layer is disposed between the silicon substrate and the passivation layer. Specifically, regarding the first side of the silicon substrate, the inner expansion layer generated during the inner expansion of the P-type polycrystalline silicon doped layer can form recombination centers on the surface of the first side of the silicon substrate due to the doping atoms (boron atoms and / or gallium atoms), thereby attracting carrier recombination and affecting the carrier tunneling efficiency. However, in this embodiment, since the first side surface of the silicon substrate is in direct contact with the first passivation layer, the influence of the inner expansion layer on the passivation effect of the passivation layer can be avoided, thereby improving the carrier tunneling efficiency. Attached Figure Description

[0045] Figure 1 A schematic diagram of the structure of a solar cell according to an embodiment of the invention;

[0046] Figure 2 This is a solar cell ECV diagram according to an embodiment of the present invention;

[0047] Figure 3 This is a schematic diagram of the structure of a solar cell according to another embodiment of the present invention;

[0048] Figure 4 This is a schematic diagram of the structure of a solar cell according to another embodiment of the present invention;

[0049] Figure 5 The process steps of the solar cell structure in this embodiment of the invention Figure 1 ;

[0050] Figure 6The process steps of the solar cell structure in this embodiment of the invention Figure 2 ;

[0051] Figure 7 The process steps of the solar cell structure in this embodiment of the invention Figure 3 ;

[0052] Figure 8 The process steps of the solar cell structure in this embodiment of the invention Figure 4 ;

[0053] Figure 9 The process steps of the solar cell structure in this embodiment of the invention Figure 5 ;

[0054] Figure 10 The process steps of the solar cell structure in this embodiment of the invention Figure 6 ;

[0055] List of reference numerals in the attached diagram:

[0056] 10. Silicon substrate; 20. First passivation layer; 21. First part; 22. Second part; 23. First porous structure; 30. Second passivation layer; 31. Third porous structure; 40. P-type polysilicon doped layer; 50. First N-type polysilicon doped layer; 60. Second N-type polysilicon doped layer; 70. Third passivation layer. Detailed Implementation

[0057] To enable those skilled in the art to better understand the technical solutions of the present invention, the solar cells, photovoltaic modules, and photovoltaic systems provided by the present invention will be described in detail below with reference to the accompanying drawings.

[0058] To address the aforementioned problems, according to a first aspect of the present invention, a solar cell is disclosed, comprising: a silicon substrate 10, a passivation layer, and a polycrystalline silicon doped layer. The passivation layer is disposed on the surface of the silicon substrate 10, and the polycrystalline silicon doped layer is disposed on the passivation layer.

[0059] In the solar cell of the present invention, the passivation layer is directly disposed on the surface of the silicon substrate 10, so that the silicon substrate 10 is in direct contact with the passivation layer. In other words, there is no longer an inner extension layer between the silicon substrate 10 and the passivation layer, which can avoid the inner extension layer from affecting the passivation effect of the passivation layer, thereby improving the carrier transport efficiency.

[0060] The structure of the solar cell of the present invention will be further described below with reference to specific embodiments.

[0061] like Figure 1 The illustrated embodiment 1 discloses a solar cell structure, including: a silicon substrate 10, a passivation layer, and a polycrystalline silicon doped layer. The silicon substrate 10 includes a first side and a second side disposed opposite to each other.

[0062] The passivation layer includes a first passivation layer 20 and a second passivation layer 30. The first passivation layer 20 is disposed on the surface of a first side of the silicon substrate 10, and the second passivation layer 30 is disposed on the surface of a second side of the silicon substrate 10.

[0063] The polysilicon doped layer includes a P-type polysilicon doped layer 40 and a first N-type polysilicon doped layer 50. The P-type polysilicon doped layer 40 is disposed on the first passivation layer 20, and the first N-type polysilicon doped layer 50 is disposed on the second passivation layer 30.

[0064] In embodiments of the present invention, by disposing of the first passivation layer 20 on the surface of the second side of the silicon substrate 10 and the second passivation layer 30 on the surface of the second side of the silicon substrate 10, both sides of the silicon substrate 10 are in direct contact with the passivation layer. In other words, no inner expansion layer is disposed between the silicon substrate 10 and the passivation layer. Specifically, regarding the first side of the silicon substrate, the inner expansion layer generated during the inner expansion of the P-type polycrystalline silicon doped layer 40 can form recombination centers on the surface of the first side of the silicon substrate 10 due to the doping atoms (boron atoms and / or gallium atoms), thereby attracting carrier recombination and affecting the carrier tunneling efficiency. However, in this embodiment, since the first side surface of the silicon substrate 10 is in direct contact with the first passivation layer 20, the influence of the inner expansion layer on the passivation effect of the passivation layer can be avoided, thereby improving the carrier tunneling efficiency.

[0065] For example, the first passivation layer 20 and the second passivation layer 30 can be one or more of silicon dioxide and aluminum oxide, and are not limited in this embodiment.

[0066] Specifically, in this example, the first passivation layer 20 includes a first portion 21 and a second portion 22. The first portion 21 has a first porous structure 23, and the second portion 22 has a closely arranged structure and does not have a porous structure. The first portion 21 is located between the silicon substrate 10 and the P-type polysilicon doped layer 40, and the second portion 22 is stacked with the first portion 21, located between the first portion 21 and the silicon substrate 10. By forming a first porous structure 23 in the first part 21 and the second part 22 not having a porous structure, during the high-temperature inward expansion step of the P-type polycrystalline silicon doped layer 40, the second part 22 can block the doped atoms (e.g., boron atoms or gallium atoms), thereby preventing the doped atoms from contacting the surface of the silicon substrate 10 and thus avoiding the formation of the inward expansion layer. Due to the presence of the first porous structure 23, in the region corresponding to the hole, the charge carriers only need to tunnel through the second part 22 to enter the hole region and complete the tunneling. The charge carriers entering the hole region move along the hole region towards the P-type polycrystalline doped layer, eliminating the need for the charge carriers to tunnel through the first part 21 again, thereby reducing the tunneling resistance.

[0067] like Figure 1As shown, in this embodiment, polysilicon is disposed in the pores of the first porous structure 23. By disposing of polysilicon in the pores of the first porous structure 23, the carrier transport efficiency can be improved and the transport resistance can be reduced.

[0068] It should be noted that, although polycrystalline silicon is disposed in the pores of the first porous structure 23 in this embodiment, this is not limiting. In other embodiments not shown in the figure, monocrystalline silicon may also be used, but this embodiment does not impose any restrictions.

[0069] For example, the average pore size of the first porous structure 23 ranges from 0.5 nm to 5.0 nm. When the average pore size is less than 0.5 nm, the pore size is too small, which will hinder carrier transport and increase contact resistance. When the average pore size is greater than 5.0 nm, the pore size is too large, which will affect the passivation effect and reduce electrical performance, resulting in a lower on-state voltage. Therefore, by limiting the average pore size of the first porous structure 23 to 0.5 nm to 5.0 nm, both good surface passivation effect and good current transport performance can be achieved.

[0070] For example, the ratio of the number of pores N1 in the first porous structure 23 to the area S1 of the first portion 21 is in the range of 1×10. 6 holes / cm 2 ≤N1 / S1≤1×10 10 holes / cm 2 That is to say, each square meter is 1×10 6 ~1×10 10 Hole. When N1 / S1 < 1 × 10 6 holes / cm 2 When the number of holes is too small, the current transmission process is limited, and this is indicated by excessively high series resistance. When N1 / S1 > 1 × 10 10 holes / cm 2 When the number of holes is too large, it indicates that a good passivation effect cannot be achieved. This is reflected in a low opening pressure. Therefore, by limiting N1 / S1 to 1×10 6 holes / cm 2 ≤N1 / S1≤1×10 10 holes / cm 2 It can achieve both good surface passivation effect and good current transmission performance.

[0071] It is understood that solar cells typically have a first direction, a second direction, and a third direction, and these three directions are mutually perpendicular. For example, the third direction is the thickness direction (Z-direction) of the solar cell. However, depending on the shape of the solar cell, the definitions of the first and second directions differ, but both are perpendicular to the third direction. For instance, when the solar cell is rectangular, the first direction can be the length direction (X-direction) and the second direction can be the width direction (Y-direction); when the solar cell is circular, the first direction can be the first radial direction (X-direction) and the second radial direction (Y-direction).

[0072] In this embodiment, taking a rectangular solar cell as an example, the first porous structure 23 includes: multiple groups of holes, which are spaced apart along a first direction. Each group of holes has multiple holes, and the holes within the same group are spaced apart along a second direction. Both the first and second directions are parallel to the first side surface of the silicon substrate 10. That is, the multiple holes of the first porous structure 23 are distributed along the first and second directions in various regions of the first portion 21 of the first passivation layer 20. Furthermore, the multiple groups of holes are divided into multiple groups of holes, with different groups spaced apart along the first direction, and the holes within the same group spaced apart along the second direction. This distribution allows the holes of the first porous structure 23 to be distributed in various regions of the first portion 21 of the first passivation layer 20, increasing the probability that charge carriers tunneling through the second portion 22 of the first passivation layer 20 will enter the holes and be transported to the P-type polycrystalline doped layer, thereby improving the carrier transport efficiency.

[0073] Within the same pore group, the pore density ranges from 1×10⁻⁶. 6 holes / cm ~1×10 10 holes / cm, where the hole density is the ratio of the number of holes N11 to the unit length D1 of the first part 21 in the first direction, i.e., 1×10⁻⁶. 6 holes / cm≤N11 / D1≤1×10 10 holes / cm, that is, in the cross-section of the first direction, there are 1×10 holes / cm. 6 ~1×10 10 Hole. If N11 / D1 < 1 × 10 6 When N11 / D1 = 1 × 10⁻⁶, it indicates that the number of holes in the first direction is too small, thus reducing the carrier transport efficiency. 10 When the number of holes / cm is too high, it indicates that there are too many holes in the first direction, which cannot form a good passivation effect. This is reflected in the low opening pressure. Therefore, by limiting N11 / D1 to 1×106 holes / cm≤N11 / D1≤1×10 10 With holes / cm, it can achieve both good surface passivation effect and good current transmission performance.

[0074] In a further embodiment, within the same group of holes, there are multiple regions spaced equidistant from each other along a first direction, and the average value of the hole density in the multiple regions ranges from 1×10⁻⁶. 6 holes / cm ~1×10 10 Holes / cm, in other words, the average value of hole density in multiple regions refers to the average value of hole density in m regions (where m is a positive integer greater than 2) obtained by first dividing the same group of holes into m regions along the first direction, then calculating the hole density in each region separately, and finally adding the hole densities in each region and dividing by m.

[0075] If the average porosity of each region is <1×10 6 A hole density of 1 / cm indicates that the hole density in each region is too low, thus affecting the carrier transport efficiency. Conversely, an average hole density of >1×10⁻⁶ indicates a lower hole density in each region. 10 When the pore density is below a certain value (holes / cm), it indicates that the pore density in each region is too high, making it impossible to achieve a good passivation effect. This is reflected in a low opening pressure. Therefore, the average pore density in each region is limited to 1×10⁻⁶. 6 holes / cm ~1×10 10 Within the range of holes / cm, it can achieve both good surface passivation effect and good current transmission performance.

[0076] In a further embodiment, within the same group of pores, the ratio of the standard deviation of the pore density in multiple regions to the average range of the pore density is 1 × 10⁻⁶. -4 ~1×10 -2 This makes the pore density in each region more similar, thereby improving the uniformity of the overall pore distribution in the first porous structure 23, and thus improving the uniformity and stability of carrier transport.

[0077] It is understandable that different pore groups are distributed at intervals on the second reverse side, and the average pore density of multiple pore groups ranges from 1×10⁻⁶. 6 holes / cm ~1×10 10 holes / cm. In other words, the average hole density of multiple hole groups refers to: first calculating the hole density of each of the m hole groups (m is a positive integer greater than 2), then adding the hole densities of the m hole groups together and dividing by m, and finally obtaining the average hole density of the m hole groups.

[0078] If the average pore density of multiple pore groups is <1×10 6 A hole density of 10 ... 10 When the number of holes / cm is high, it indicates a large number of holes in the second direction, which prevents a good passivation effect. This indicates a low opening pressure. Therefore, the average hole density in each region is limited to 1×10⁻⁶. 6 holes / cm ~1×10 10 Within the range of holes / cm, it can achieve both good surface passivation effect and good current transmission performance.

[0079] In a further embodiment, the ratio of the standard deviation of the pore density of the plurality of pore groups to the average range of the pore density is 1 × 10⁻⁶. -4 ~1×10 -2 In the second direction, the ratio of the standard deviation of the pore density of multiple pore groups to the average range of the pore density represents the fluctuation of the pore density of each pore group. When the ratio of the standard deviation of the pore density of multiple pore groups to the average range of the pore density is 1 × 10⁻⁶, the fluctuation is considered to be within the range of 1 × 10⁻⁶. -4 ~1×10 -2 This indicates that the pore density of each pore group is relatively close, thereby improving the uniformity of the overall pore distribution in the first porous structure 23, and thus improving the uniformity and stability of carrier transport.

[0080] In this embodiment, the first passivation layer 20 has a first side and a second side. The first side of the first passivation layer 20 is away from the silicon substrate 10, and a P-type polysilicon doped layer 40 is disposed on the surface of the first side of the first passivation layer 20; the second side of the first passivation layer 20 faces the silicon substrate 10 and is in contact with the silicon substrate 10.

[0081] During the diffusion process, doped atoms gradually diffuse from the first side of the first passivation layer 20 to the second side of the first passivation layer 20. Therefore, the doping concentration gradually decreases in the direction from the first side to the second side of the first passivation layer 20. In other words, the doping concentration is higher at the location on the first passivation layer 20 that is farther away from the silicon substrate 10.

[0082] Since the first part 21 is closer to the P-type polysilicon doped layer 40 than the second part 22, the doping concentration of the first part 21 is greater than that of the second part 22.

[0083] Furthermore, since the first portion 21 of the first passivation layer 20 has a first porous structure 23, during diffusion, doped atoms can diffuse more extensively into the first portion 21 through the first porous structure 23. However, since the second portion 22 does not have a porous structure, most of the doped atoms are blocked between the first portion 21 and the second portion 22, thus preventing the dopant from penetrating the second portion 22 and contacting the silicon substrate 10 to form an inner diffusion layer. Therefore, overall, the doping concentration in the second portion 22 of the first passivation layer 20 is relatively low.

[0084] It is understandable that the doping concentration on the second side of the first passivation layer 20 is less than the doping concentration of the p-type polysilicon doped layer 40. Since the silicon substrate 10 is in contact with the second side of the first passivation layer 20, that is, the doping concentration on the side of the silicon substrate 10 in contact with the first passivation layer 20 is less than the doping concentration of the p-type polysilicon doped layer 40. For example, the doping concentration on the side of the silicon substrate 10 in contact with the passivation layer is a2, and the value of a2 ranges from 1.5 × 10⁻⁶. 14 atom / cm 3 ~1.5×10 17 atom / cm 3 .

[0085] like Figure 2 As shown, Figure 2 This is an ECV (electrochemical capacitance-voltage) graph of a solar cell in this embodiment. The horizontal axis represents the depth from the surface of the P-type polycrystalline silicon doped layer 40 to the silicon substrate 10, which is the thickness of the solar cell. The vertical axis represents the doping concentration.

[0086] exist Figure 2 In the diagram, the distance between point 0 and point A on the horizontal axis represents the thickness of the P-type polysilicon doped layer 40, and the distance between point A and point B represents the thickness D of the first passivation layer 20. Figure 2 The area to the right of point B represents region 10 of the silicon substrate.

[0087] like Figure 2 As shown, the thickness of the P-type polysilicon doped layer 40 corresponds to the doping concentration a1, and the value of a1 ranges from 1 × 10⁻⁶. 19 ~1.5×10 20 atom / cm 3 The region from point 0 to point E is the area near the surface of the P-type polysilicon doped layer 40 facing away from the silicon substrate 10, with a depth ranging from 0.005 to 0.05 μm. In this region, the doping concentration gradually increases with depth. The region from point E to point A is the area closer to the interior of the P-type polysilicon doped layer 40. After entering this region, the doping concentration remains basically stable. The concentration difference between point 0 and point E ranges from 0.5 × 10⁻⁶. 19 -4.5×1019 .

[0088] like Figure 2 As shown, point A to point B represents the thickness D of the first passivation layer 20. Within this region, the doping concentration decreases significantly. The rate of change of the doping concentration of the first passivation layer 20 along its thickness direction is ΔX1. For example, ΔX1 ranges from 2.5 × 10⁻⁶. 24 atom / cm 4 ≤△X1≤1.5×10 26 atom / cm 4 .

[0089] In this embodiment, the doping concentration change rate ΔX of the first passivation layer 20 in its thickness direction is obtained according to the following formula:

[0090] △X1=(X MAX -X MIN Formula 1 (D)

[0091] Among them, X MAX X represents the maximum doping concentration in the first passivation layer 20. MIN D is the minimum doping concentration in the first passivation layer 20, and D is the thickness of the first passivation layer 20.

[0092] like Figure 2 As shown, the doping concentration at point A is the highest. This doping concentration is the same as the doping concentration corresponding to the thickness of the P-type polysilicon doped layer 40, i.e., a1, or X. MAX =a1, while the doping concentration at point B is the lowest, which is the doping concentration a2 on the side where the silicon substrate 10 contacts the passivation layer, i.e., X. MIN =a2, where D is the thickness of the first passivation layer 20. Therefore, by substituting the specific data into the formula in Equation 1, the value of ΔX1 can be obtained.

[0093] In this embodiment, the thickness D of the first passivation layer 20 is 1.5 nm to 4.0 nm. The thickness D1 of the first portion 21 is 0.3 nm to 1.6 nm, and the thickness D2 of the second portion 22 is 1.2 nm to 2.4 nm.

[0094] In this embodiment, when D1 < 0.3 nm, it indicates that the thickness of the first part 21 is too thin. When the first part 21 is too thin, it produces more pores during the diffusion process, and the average pore size is larger. This results in a large number of doped atoms diffusing into the second part 22. When too many doped atoms diffuse into the second part 22, even if the second part 22 of the first passivation layer 20 can block most of the doped atoms, due to the increased number of doped atoms, a large number of doped atoms will still pass through the second part 22 and combine with the surface of the silicon substrate 10 to form an inner diffusion layer, thereby weakening the passivation effect. When D1 > 1.6 nm, it indicates that the thickness of the first part 21 is too thick. When the first part 21 is too thick, it produces fewer pores during the diffusion process, and the average pore size is smaller. This reduces the number of pores that carriers can utilize by tunneling through the second part 22, thereby reducing the carrier transport efficiency. Therefore, by limiting the thickness D1 of the first part 21 to a range of 0.3 nm to 1.6 nm, the carrier transport efficiency can be guaranteed while ensuring the blocking effect.

[0095] In this embodiment, when D2 < 1.2 nm, it indicates that the thickness of the second part 22 is too thin. When the first part 21 is too thin, its effect of blocking dopant atoms decreases, resulting in more dopant atoms passing through the second part 22 and bonding with the surface of the silicon substrate 10 to form an inner extension layer, thereby weakening the passivation effect. When D2 > 2.4 nm, it indicates that the thickness of the second part 22 is too thick. When the second part is too thick, it becomes more difficult for charge carriers to tunnel through the second part 22, in other words, the tunneling efficiency of charge carriers decreases, thereby reducing the transport efficiency of charge carriers. Therefore, by limiting the thickness D2 of the second part 22 to the range of 1.2 nm to 2.4 nm, both the blocking effect and the transport efficiency of charge carriers can be guaranteed.

[0096] By setting the thickness D of the first passivation layer 20 to a range of 1.5 nm to 4.0 nm, the minimum or maximum values ​​of the first part 21 and the second part 22 of the first passivation layer 20 can be satisfied, thereby balancing the blocking effect and the carrier transport efficiency.

[0097] In this embodiment, the oxygen-silicon ratio in the first passivation layer 20 ranges from 1.5 to 2.0. By limiting the oxygen-silicon ratio to 1.5 to 2.0, the oxygen-silicon ratio can be made as close to 2 / 1 as possible, thereby reducing the dangling bonds at the interface of the first passivation layer 20, and thus reducing the recombination consumption of charge carriers with dangling bonds when passing through the interface of the first passivation layer 20, thereby improving the transport efficiency of charge carriers.

[0098] It should be noted that, in Figure 1In the illustrated embodiment, the first portion 21 of the first passivation layer 20 has a first porous structure 23, while the second portion 22 does not have a through-hole structure; however, this is not limiting. In other embodiments, the second portion 22 of the first passivation layer 20 may also have a second porous structure. The average pore size of the second porous structure is smaller than the average pore size of the first porous structure 23. In this embodiment, by making the average pore size of the second porous structure smaller than the average pore size of the first porous structure 23, most of the doped atoms are blocked by the second portion 22 of the first passivation layer 20. Simultaneously, the tunneling efficiency of charge carriers can be improved through the second porous structure.

[0099] The ratio of the number of pores in the second porous structure to the area of ​​the second part 22 is smaller than the ratio of the number of pores in the first porous structure 23 to the area of ​​the first part 21. By making the ratio of the number of pores in the second porous structure to the area of ​​the second part 22 smaller than the ratio of the number of pores in the first porous structure 23 to the area of ​​the first part 21, in other words, the pore density of the second porous structure is smaller than the pore density of the first porous structure 23, which is equivalent to making the number of pores in the second part 22 less and smaller, thereby increasing the blocking effect on doped atoms.

[0100] In such Figure 1 In the illustrated embodiment, the thickness of the second passivation layer 30 ranges from 0.5 nm to 1.5 nm. By setting the thickness of the second passivation layer 30 to 0.5 nm to 1.5 nm, the tunneling efficiency of the second passivation layer 30 can be guaranteed. In this embodiment, the doping concentration variation rate of the second passivation layer 30 in its thickness direction is ΔX2, 2.5 × 10⁻⁶. 25 atom / cm 4 ≤△X2≤1.5×10 27 atom / cm 4 .

[0101] In this embodiment, the oxygen-silicon ratio in the second passivation layer 30 ranges from 1.5 to 2.0. By limiting the oxygen-silicon ratio to 1.5 to 2.0, the oxygen-silicon ratio can be made as close to 2 / 1 as possible, thereby reducing the dangling bonds at the interface of the second passivation layer 30, and thus reducing the recombination consumption of charge carriers with dangling bonds when passing through the interface of the second passivation layer 30, thereby improving the transport efficiency of charge carriers.

[0102] For example, the doping concentration of the first N-type polysilicon doped layer 50 ranges from 1.0 × 10⁻⁶. 20 atom / cm 3 ~1.5×10 21 atom / cm 3 .

[0103] For example, the first N-type polysilicon doped layer 50 includes phosphorus atoms.

[0104] In this embodiment, the second passivation layer 30 has a first side and a second side. The first side of the second passivation layer 30 is away from the silicon substrate 10, and a first N-type polysilicon doped layer 50 is disposed on the surface of the first side of the second passivation layer 30; the second side of the second passivation layer 30 faces the silicon substrate 10 and is in contact with the silicon substrate 10.

[0105] During the diffusion process, doped atoms gradually diffuse from the first side of the second passivation layer 30 to the second side of the second passivation layer 30. Therefore, the doping concentration gradually decreases in the direction from the first side to the second side of the second passivation layer 30. In other words, the doping concentration is higher at locations on the second passivation layer 30 that are farther away from the silicon substrate 10.

[0106] It is understood that the doping concentration on the second side of the second passivation layer 30 is less than the doping concentration of the N-type polysilicon doped layer. Since the silicon substrate 10 is in contact with the second side of the second passivation layer 30, that is, the doping concentration on the side of the silicon substrate 10 in contact with the second passivation layer 30 is less than the doping concentration of the N-type polysilicon doped layer. For example, the doping concentration range on the side of the silicon substrate 10 in contact with the passivation layer is 1.5 × 10⁻⁶. 14 atom / cm 3 ~1.5×10 17 atom / cm 3 .

[0107] It should be noted that in the above embodiments, a second passivation layer 30 and a first N-type polysilicon doped layer 50 are sequentially disposed on the second side of the silicon substrate 10. In other words, a passivation layer and an N-type polysilicon doped layer are disposed on the N side of the silicon substrate 10. However, this is not limiting. In other embodiments, multiple passivation layers and multiple N-type polysilicon doped layers may be disposed on the second side of the silicon substrate 10, and the order can be interchanged. This application does not impose any restrictions on this.

[0108] Specifically, such as Figure 3 In another embodiment shown, a solar cell is also disclosed, with a structure basically the same as the above embodiment. The difference is that in this embodiment, the passivation layer further includes a third passivation layer 70; the polycrystalline silicon doped layer further includes a second N-type polycrystalline silicon doped layer 60. The third passivation layer 70 is disposed on the surface of the first N-type polycrystalline silicon doped layer 50 on the side opposite to the silicon substrate 10; the second N-type polycrystalline silicon doped layer 60 is disposed on the third passivation layer 70.

[0109] In this embodiment, by setting a first N-type polycrystalline silicon doped layer 50 and a second N-type polycrystalline silicon doped layer 60, a multilayer polycrystalline silicon doped layer is formed, which can reduce parasitic absorption, improve the long-wavelength response of sunlight, increase the short-circuit current of the device, and effectively improve the photoelectric conversion efficiency of the battery. That is, the present invention solves the parasitic absorption problem while ensuring the passivation contact performance of the battery.

[0110] like Figure 4 As shown, the present invention also discloses another embodiment, which also discloses a solar cell with a structure basically the same as the above embodiment. The difference is that in this embodiment, the order of the passivation layer and the polycrystalline silicon doped layer is adjusted.

[0111] Specifically, such as Figure 4 As shown, the polysilicon doped layer includes: a first N-type polysilicon doped layer 50 and a second N-type polysilicon doped layer 60. The first N-type polysilicon doped layer 50 is disposed on the second side surface of the silicon substrate 10, and the second N-type polysilicon doped layer 60 is disposed on the first side of the first N-type polysilicon doped layer 50 away from the silicon substrate 10.

[0112] The passivation layer includes a second passivation layer 30 disposed between a first N-type polysilicon doped layer 50 and a second N-type polysilicon doped layer 60. A third porous structure 31 is disposed on the second passivation layer 30, and the pores of the third porous structure 31 are filled with polysilicon. The polysilicon within the third porous structure 31 connects the first N-type polysilicon doped layer 50 and the second N-type polysilicon doped layer 60. For example, the polysilicon within the third porous structure 31 is N-type doped polysilicon.

[0113] In this embodiment, since the doping atoms in the first N-type polysilicon doped layer 50 are typically phosphorus atoms, and phosphorus atoms do not form recombination centers with the silicon substrate 10, the first N-type polysilicon doped layer 50 can be disposed on the surface of the silicon substrate 10.

[0114] A third porous structure 31 is formed on the second passivation layer 30, and the pores of the third porous structure 31 are filled with polysilicon. The polysilicon in the third porous structure 31 connects the first N-type polysilicon doped layer 50 and the second N-type polysilicon doped layer 60. This forms conductive channels in the pore region, thereby creating a good resistivity for the second passivation layer 30. This reduces the sensitivity of the thickness of the second passivation layer 30 to the influence of resistance, thus reducing the control requirements for the thickness of the second passivation layer 30. Therefore, the preparation method of the second passivation layer 30 can be more diverse than existing methods. At the same time, by setting the first N-type polysilicon doped layer 50 between the silicon substrate 10 and the second passivation layer 30, a separation electric field that enhances the surface electron-hole separation can be formed, thereby improving the field passivation effect. Furthermore, since the first N-type polysilicon doped layer 50 has a different Fermi level than the silicon substrate 10, the first N-type polysilicon doped layer 50 changes the Fermi level, which increases the solid concentration of impurities (transition metals), achieving an additional gettering effect.

[0115] In addition, the second doped layer is connected to the silicon substrate through the third porous structure 31 and the first doped layer, and the pores of the third porous structure 31 are N-type doped polycrystalline silicon. Therefore, the overall resistance of the prepared cell is further reduced, and the conversion efficiency of the cell is ultimately improved. This solves the problem that the precise thickness requirements of the existing tunneling layer make it difficult to produce and limit the conversion efficiency.

[0116] According to another aspect of the present invention, a method for preparing the above-described solar cell is also disclosed, comprising:

[0117] A passivation layer is prepared on one side of the silicon substrate 10, and a first porous structure 23 is formed on the side of the passivation layer opposite to the silicon substrate 10.

[0118] A P-type polycrystalline silicon doped layer 40 is prepared on the side of the passivation layer away from the silicon substrate 10.

[0119] The method for preparing solar cells of the present invention forms a first porous structure 23 on the side of the passivation layer away from the silicon substrate 10, which can avoid the inner expansion layer from affecting the passivation effect of the passivation layer, and at the same time, can improve the tunneling efficiency of charge carriers.

[0120] The following is based on Figure 1 Taking the solar cell shown as an example, the method for preparing the solar cell of the present invention will be further explained in conjunction with specific preparation steps.

[0121] In this embodiment, the method for preparing a solar cell includes the following steps:

[0122] S10: Clean the silicon substrate 10. (Example) Figure 5 As shown, the surface of silicon substrate 10 is cleaned.

[0123] S20: A P-type polycrystalline silicon doped layer 40 is formed on the first side of the passivation layer away from the silicon substrate 10. Specifically, S20 includes:

[0124] S21: A first portion 21 of a first passivation layer 20 is grown on a first side surface of a silicon substrate 10. For example... Figure 6 As shown, after the silicon substrate 10 is cleaned, an oxide layer is grown on the first side of the silicon substrate 10 to form the first portion 21 of the first passivation layer 20.

[0125] S22: Annealing the first portion 21 to form a first porous structure 23. After the first portion 21 is deposited, the first portion 21 of the first passivation layer 20 is annealed to make the first portion 21 of the first passivation layer 20 shaped as follows: Figure 7 The first porous structure 23 is shown.

[0126] S22: A second portion 22 of the first passivation layer 20 is grown between the silicon substrate 10 and the first portion 21, such that the second portion 22 is located between the first porous structure 23 and the silicon substrate 10. Figure 8 As shown, the second part 22, which has been passivated by the first method, continues to grow. Since the pores of the first porous structure 23 penetrate the first part 21, the bottom of the pores extends to the surface of the silicon substrate 10. During the growth of the second part 22, oxygen atoms enter the pores and combine with the silicon substrate 10 surface at the bottom of the pores to form a new oxide layer, which gradually diffuses laterally, eventually forming a layer as shown in the diagram. Figure 8 The second portion 22 of the second passivation layer 30 is shown. Therefore, the newly formed second portion 22 will seal the bottom of the holes of the first porous structure 23, thereby isolating the first portion 21 and the holes of the first portion 21 from the surface of the silicon substrate 10.

[0127] S30: A P-type polycrystalline silicon doped layer 40 is prepared on the side of the passivation layer facing away from the silicon substrate 10. Specifically, step S30 includes:

[0128] S31: After the second portion 22 is formed, a poly layer is grown on the side of the first portion 21 opposite to the silicon substrate 10. After the second portion 22 is grown, as... Figure 9 As shown, a poly layer (polycrystalline silicon layer) needs to be deposited on the surface of the second part 22. During the poly layer deposition process, some polycrystalline silicon will enter the pores of the first porous structure 23, thereby filling the pores and forming a conductive structure.

[0129] S32: Boron atoms are diffused into the poly layer to form a P-type polycrystalline silicon doped layer 40. After the poly layer is grown, boron atoms are implanted and high-temperature diffusion is performed to allow the doped atoms to diffuse into the poly layer, thereby forming a P-type polycrystalline silicon doped layer 40. Since the first part 21 of the first passivation layer 20 has already formed the first porous structure 23, no new porous structures will be added during high-temperature diffusion. By controlling the thickness of the second part 22 of the first passivation layer 20, the second part 22 can be made relatively thin, which is more conducive to carrier tunneling, without generating porous structures or a small number of porous structures.

[0130] S40: A second passivation layer 30 is grown on the second side of the silicon substrate 10.

[0131] S50: A first N-type polycrystalline silicon doped layer 50 is prepared on the side of the second passivation layer 30 away from the silicon substrate 10.

[0132] In the method for preparing solar energy according to the present invention, the first passivation layer 20 is divided into two parts and the two parts are prepared stepwise. This allows the first part 21 to form a porous structure, while the second part 22 may not form a porous structure or may have a small amount of porous structure. Since the first part 21 has a porous structure and the pores of the porous structure are filled with doped polycrystalline silicon, conductive channels can be formed. Since the second part 22 has no pores or fewer pores, it can block the diffusion of boron atoms, preventing boron atoms from forming an inner diffusion layer on the surface of the silicon substrate 10, thereby reducing the generation of recombination centers and improving the passivation effect. At the same time, since the second part 22 can be thinner, the tunneling efficiency can be improved. The pores and the conductive channels formed by the doped polycrystalline silicon in the pores can improve the transport efficiency of charge carriers after tunneling, thereby improving the conductivity of the first passivation layer 20.

[0133] For example, the second part 22 includes silicon oxide, wherein the ratio of oxygen atoms to silicon atoms ranges from 1.5 to 2.0.

[0134] According to a second aspect of the invention, a photovoltaic module is also disclosed, including the solar cell described above.

[0135] According to a third aspect of the invention, a photovoltaic system comprising the aforementioned photovoltaic module is also disclosed.

[0136] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A solar cell, characterized in that, include: Silicon substrate (10); A passivation layer is disposed on the surface of the silicon substrate (10); A polycrystalline silicon doped layer is disposed on the passivation layer.

2. The solar cell according to claim 1, characterized in that, The silicon substrate (10) includes a first side and a second side disposed opposite to each other; The passivation layer includes: a first passivation layer (20) disposed on the surface of the silicon substrate (10) on a first side; The polysilicon doped layer includes a P-type polysilicon doped layer (40) disposed on the first passivation layer (20).

3. The solar cell according to claim 2, characterized in that, The first passivation layer (20) includes: The first part (21) has a first porous structure (23) and is located between the silicon substrate (10) and the P-type polycrystalline silicon doped layer (40); The second part (22) is superimposed on the first part (21), and the second part (22) is located between the first part (21) and the silicon substrate (10).

4. The solar cell according to claim 3, characterized in that, The pores of the first porous structure (23) are filled with monocrystalline silicon.

5. The solar cell according to claim 3, characterized in that, The ratio of the number of pores in the first porous structure (23) to the area of ​​the first portion (21) ranges from 1×10. 6 holes / cm 2 ~1×10 10 holes / cm 2 .

6. The solar cell according to claim 3, characterized in that, The first porous structure (23) includes: Multiple groups of holes are spaced apart along a first direction, each group of holes has multiple holes, and the holes in the same group are spaced apart along a second direction. Both the first direction and the second direction are parallel to the first side surface of the silicon substrate (10), and the first direction and the second direction intersect.

7. The solar cell according to claim 6, characterized in that, Within the same group of pores, the pore density ranges from 1×10⁻⁶. 6 holes / cm ~1×10 10 holes / cm, wherein the hole density is the ratio of the number of holes to the unit length of the first portion (21) in the first direction.

8. The solar cell according to claim 7, characterized in that, Within the same group of pores, there are multiple regions spaced equidistant from each other along the first direction, and the average pore density within these multiple regions ranges from 1 × 10⁻⁶. 6 holes / cm ~1×10 10 holes / cm.

9. The solar cell according to claim 8, characterized in that, Within the same group of pores, the ratio of the standard deviation of the pore density to the average range of the pore density in the plurality of regions is 1 × 10⁻⁶. -4 ~1×10 -2 .

10. The solar cell according to claim 7, characterized in that, The average pore density of the multiple pore groups ranges from 1×10⁻⁶. 6 holes / cm ~1×10 10 holes / cm.

11. The solar cell according to claim 10, characterized in that, The ratio of the standard deviation of the pore density of the plurality of pore groups to the range of the average pore density is 1×10. -4 ~1×10 -2 .

12. The solar cell according to claim 3, characterized in that, The second part (22) has a second porous structure, the average pore size of the second porous structure being smaller than the average pore size of the first porous structure (23).

13. The solar cell according to claim 12, characterized in that, The ratio of the number of pores in the second porous structure to the area of ​​the second part (22) is less than the ratio of the number of pores in the first porous structure (23) to the area of ​​the first part (21).

14. The solar cell according to claim 3, characterized in that, The doping concentration of the first part (21) is greater than that of the second part (22).

15. The solar cell according to claim 2, characterized in that, The doping concentration is higher at locations on the first passivation layer (20) that are farther away from the silicon substrate (10).

16. The solar cell according to claim 15, characterized in that, The doping concentration of the first passivation layer (20) varies with the thickness direction by a rate of ΔX1, 2.5 × 10⁻⁶. 24 atom / cm 4 ≤△X1≤1.5×10 26 atom / cm 4 .

17. The solar cell according to claim 16, characterized in that, The doping concentration variation rate ΔX of the first passivation layer (20) in its thickness direction is obtained according to the following formula: △X1=(X MAX -X MIN ) / D; Among them, X MAX X is the maximum doping concentration in the first passivation layer (20). MIN D is the minimum doping concentration in the first passivation layer (20), and D is the thickness of the first passivation layer (20).

18. The solar cell according to claim 3, characterized in that, The thickness D of the first passivation layer (20) ranges from 1.5 nm to 4.0 nm.

19. The solar cell according to claim 18, characterized in that, The thickness range D2 of the second part (22) is 1.2nm~2.4nm.

20. The solar cell according to claim 2, characterized in that, The oxygen-to-silicon ratio in the first passivation layer (20) ranges from 1.5 to 2.

0.

21. The solar cell according to claim 2, characterized in that, The doping concentration of the p-type polycrystalline silicon doped layer (40) ranges from 1.0 × 10⁻⁶. 19 atom / cm 3 ~1.5×10 20 atom / cm 3 .

22. The solar cell according to claim 2, characterized in that, The P-type polycrystalline silicon doped layer (40) includes boron atoms and / or gallium atoms.

23. The solar cell according to claim 2, characterized in that, The doping concentration on the side of the silicon substrate (10) that is in contact with the first passivation layer (20) is less than the doping concentration of the P-type polycrystalline silicon doped layer (40).

24. The solar cell according to claim 22, characterized in that, The doping concentration on the side of the silicon substrate (10) that contacts the passivation layer is in the range of 1.5 × 10⁻⁶. 14 atom / cm 3 ~1.5×10 17 atom / cm 3 .

25. The solar cell according to claim 1, characterized in that, The silicon substrate (10) includes a first side and a second side disposed opposite to each other; The passivation layer includes: a second passivation layer (30) disposed on the surface of the second side of the silicon substrate (10); The polysilicon doped layer includes a first N-type polysilicon doped layer (50) disposed on the second passivation layer (30).

26. The solar cell according to claim 25, characterized in that, The thickness of the second passivation layer (30) ranges from 0.5 nm to 1.5 nm.

27. The solar cell according to claim 25, characterized in that, The doping concentration of the second passivation layer (30) varies with ΔX2, 2.5 × 10⁻⁶ along its thickness direction. 25 atom / cm 4 ≤△X2≤1.5×10 27 atom / cm 4 .

28. The solar cell according to claim 25, characterized in that, The oxygen-to-silicon ratio in the second passivation layer (30) ranges from 1.5 to 2.

0.

29. The solar cell according to claim 25, characterized in that, The doping concentration of the first N-type polycrystalline silicon doped layer (50) ranges from 1.0 × 10⁻⁶. 20 atom / cm 3 ~1.5×10 21 atom / cm 3 .

30. The solar cell according to claim 25, characterized in that, The first N-type polycrystalline silicon doped layer (50) includes phosphorus atoms.

31. The solar cell according to claim 25, characterized in that, The doping concentration on the side of the silicon substrate (10) that contacts the second passivation layer (30) is less than the doping concentration of the first N-type polysilicon doped layer (50).

32. The solar cell according to claim 30, characterized in that, The doping concentration on the side of the silicon substrate (10) that contacts the second passivation layer (30) is in the range of 1.5 × 10⁻⁶. 14 atom / cm 3 ~1.5×10 17 atom / cm 3 .

33. The solar cell according to claim 25, characterized in that, The passivation layer further includes: a third passivation layer (70), disposed on the surface of the first N-type polysilicon doped layer (50) on the side opposite to the silicon substrate (10); The polysilicon doped layer further includes a second N-type polysilicon doped layer (60) disposed on the third passivation layer (70).

34. The solar cell according to claim 1, characterized in that, The silicon substrate (10) includes a first side and a second side disposed opposite to each other; The polysilicon doped layer includes: a first N-type polysilicon doped layer (50) and a second N-type polysilicon doped layer (60), wherein the first N-type polysilicon doped layer (50) is disposed on the second side surface of the silicon substrate (10), and the second N-type polysilicon doped layer (60) is disposed on the first side of the first N-type polysilicon doped layer (50) away from the silicon substrate (10); The passivation layer includes: a second passivation layer (30) disposed between the first N-type polysilicon doped layer (50) and the second N-type polysilicon doped layer (60), and a third porous structure (31) disposed on the second passivation layer (30), the third porous structure (31) being filled with polysilicon, and the polysilicon in the third porous structure (31) connecting the first N-type polysilicon doped layer (50) and the second N-type polysilicon doped layer (60).

35. A photovoltaic module, characterized in that, The solar cell includes any one of claims 1 to 34.

36. A photovoltaic system, characterized in that, Includes the photovoltaic module as described in claim 35.

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