Solar cell, preparation method thereof and photovoltaic module

Abstract

The invention relates to the technical field of solar cells, in particular to a solar cell, a preparation method thereof and a photovoltaic module. The solar cell of the present application comprises: a silicon substrate; the silicon substrate is provided with a first surface and a second surface which are oppositely arranged; the first intrinsic layer, the N-type doped layer and the first transparent conductive film layer are sequentially arranged on the first surface of the silicon substrate; the second intrinsic layer, the P-type doped layer and the second transparent conductive film layer are sequentially arranged on the second surface of the silicon substrate; and the P-type doped layer comprises a first P-type doped layer, a second P-type doped layer and a third P-type doped layer which are arranged in sequence. According to the solar cell, carrier transportation can be enhanced, a hole contact barrier is reduced, and the conversion efficiency of the cell is remarkably improved.

Description

Technical Field

[0001] This application relates to the technical field of solar cells, and particularly to solar cells, their preparation methods, and photovoltaic modules. Background Art

[0002] Heterojunction solar cells (HJT) have advantages such as high open-circuit voltage and high conversion efficiency, and have always received extensive attention. In order to optimize the optical response of heterojunction cells and reduce the parasitic absorption of amorphous silicon and microcrystalline silicon, N-type and P-type microcrystalline silicon oxides are often used as window layers, intermediate reflection layers, etc. of heterojunction cells. For the back hole carrier transport, the hole tunneling through the interface barrier between the microcrystalline silicon oxide and the transparent conductive film layer increases, affecting the improvement of cell efficiency. Therefore, the doping layer on the back of the HJT cell still needs to be improved. Summary of the Invention

[0003] This application aims to solve at least one of the technical problems in the related art to some extent. For this purpose, this application proposes a solar cell with high conversion efficiency, its preparation method, and a photovoltaic module.

[0004] In the first aspect of this application, a solar cell is provided, including: a silicon substrate; the silicon substrate has a first surface and a second surface arranged oppositely; a first intrinsic layer, an N-type doping layer, and a first transparent conductive film layer are sequentially arranged on the first surface of the silicon substrate; a second intrinsic layer, a P-type doping layer, and a second transparent conductive film layer are sequentially arranged on the second surface of the silicon substrate; the P-type doping layer includes a first P-type doping layer, a second P-type doping layer, and a third P-type doping layer arranged in sequence; the first P-type doping layer is in contact with the second intrinsic layer; the oxygen doping concentration of the third P-type doping layer < the oxygen doping concentration of the second P-type doping layer ≤ the oxygen doping concentration of the first P-type doping layer; the boron doping concentration of the third P-type doping layer ≥ the boron doping concentration of the second P-type doping layer > the boron doping concentration of the first P-type doping layer; the boron doping concentration of the first P-type doping layer is 0 to 1×10 5 cm -3In this application, while designing the first P-type doping layer, the second P-type doping layer, and the third P-type doping layer in a solar cell, the magnitude relationship between the oxygen doping concentration and the boron doping concentration of the three P-type doping layers is set. Among them, the first P-type doping layer has a relatively high oxygen doping concentration and a relatively low boron doping concentration. The relatively low boron doping concentration can prevent boron in the subsequent second P-type doping layer or third P-type doping layer from entering the second intrinsic layer and affecting the passivation effect of the second intrinsic layer. Compared with the first P-type doping layer, the oxygen doping concentration of the second P-type doping layer is reduced, which can improve the light transmittance of the battery and also improve hole transport. Compared with the first P-type doping layer, the boron doping concentration of the second P-type doping layer is increased, which can establish a hole conduction network and thus improve the conversion efficiency of the battery. The third P-type doping layer has the highest boron doping concentration, which can improve the contact with the second transparent conductive film layer and increase the probability of back surface hole tunneling. Thus, the solar cell of this application can enhance the transport of carriers, reduce the hole contact barrier, and significantly improve the conversion efficiency of the battery.

[0005] According to an embodiment of the present application, the ratio of the oxygen doping concentration of the first P-type doping layer to the oxygen doping concentration of the second P-type doping layer is (1~1000):1.

[0006] According to an embodiment of the present application, the ratio of the boron doping concentration of the second P-type doping layer to the boron doping concentration of the third P-type doping layer is 1:(1~100).

[0007] According to an embodiment of the present application, the oxygen doping concentration of the first P-type doping layer is 1×10 20 cm -3 ~1×10 22 cm -3 。

[0008] According to an embodiment of the present application, the oxygen doping concentration of the second P-type doping layer is 1×10 19 cm -3 ~1×10 20 cm -3 。

[0009] According to an embodiment of the present application, the boron doping concentration of the second P-type doping layer is 1×10 19 cm -3 ~1×10 20 cm -3 。

[0010] According to an embodiment of the present application, the oxygen doping concentration of the third P-type doping layer is 0~1×10 12 cm -3 。

[0011] According to an embodiment of the present application, the boron doping concentration of the third P-type doping layer is 1×1020 cm -3 ~1×10 21 cm -3 。

[0012] According to an embodiment of the present application, the thickness ratio of the first P-type doping layer, the second P-type doping layer, and the third P-type doping layer is 1:(10-25):(1-5).

[0013] According to an embodiment of the present application, the thickness of the first P-type doping layer is 1 nm to 2 nm.

[0014] According to an embodiment of the present application, the thickness of the second P-type doping layer is 20 nm to 25 nm.

[0015] According to an embodiment of the present application, the thickness of the third P-type doping layer is 3 nm to 5 nm.

[0016] According to an embodiment of the present application, the first P-type doping layer overlaps with the N-type doping layer on the side surface of the silicon substrate, and the first P-type doping layer is disposed outside the N-type doping layer.

[0017] According to an embodiment of the present application, the second intrinsic layer is disposed on the second surface and the side surface of the silicon substrate; The first intrinsic layer is disposed on the first surface of the silicon substrate and the side surface of the second intrinsic layer; The N-type doping layer is disposed on the side surface of the first intrinsic layer and the surface of the first intrinsic layer away from the silicon substrate; The first P-type doping layer is disposed on the side surface of the N-type doping layer and the surface of the second intrinsic layer away from the silicon substrate; The second P-type doping layer is disposed on the side surface of the first P-type doping layer and the surface of the first P-type doping layer away from the second intrinsic layer; The third P-type doping layer is disposed on the side surface of the second P-type doping layer and the surface of the second P-type doping layer away from the first P-type doping layer.

[0018] According to an embodiment of the present application, the first surface is the main light-receiving surface, and the second surface is the secondary light-receiving surface.

[0019] According to an embodiment of the present application, the conductivity type of the silicon substrate is N-type, and a PN junction is formed on the secondary light-receiving surface.

[0020] In a second aspect of the present application, a method for manufacturing a solar cell is provided, including the following steps: Successively prepare a first intrinsic layer, an N-type doping layer, and a first transparent conductive film layer on the first surface of the silicon substrate; A second intrinsic layer, a P-type doping layer, and a second transparent conductive film layer are sequentially prepared on the second surface of the silicon substrate; Preparing the first P-type doping layer includes: performing a first doping process on the surface of the second intrinsic layer away from the silicon substrate to obtain the first P-type doping layer; Preparing the second P-type doping layer includes: performing a second doping process on the surface of the first P-type doping layer away from the second intrinsic layer to obtain the second P-type doping layer; Preparing the third P-type doping layer includes: performing a third doping process on the surface of the second P-type doping layer away from the first P-type doping layer to obtain the third P-type doping layer.

[0021] The preparation process of the method of this application is simple and the cost is low, and a solar cell with a high conversion efficiency can be obtained.

[0022] According to an embodiment of this application, H2, silane, and an oxygen source are introduced in the first doping process.

[0023] According to an embodiment of this application, H2, silane, an oxygen source, and a boron source are introduced in the second doping process.

[0024] According to an embodiment of this application, one or more of H2, silane, an oxygen source, and a boron source are introduced in the third doping process.

[0025] According to an embodiment of this application, the introduction amount of the oxygen source in the third doping process < the introduction amount of the oxygen source in the second doping process ≤ the introduction amount of the oxygen source in the first doping process.

[0026] According to an embodiment of this application, the introduction amount of the oxygen source in the third doping process is greater than the introduction amount of the oxygen source in the first doping process.

[0027] According to an embodiment of this application, the introduction amount of the boron source in the third doping process ≥ the introduction amount of the boron source in the second doping process > the introduction amount of the boron source in the first doping process.

[0028] According to an embodiment of this application, the method for preparing a solar cell includes the following steps: Preparing the second intrinsic layer on the second surface and the side surface of the silicon substrate; Preparing the first intrinsic layer on the first surface of the silicon substrate and the side surface of the second intrinsic layer; Preparing the N-type doping layer on the side surface of the first intrinsic layer and the surface away from the silicon substrate; Preparing the first P-type doping layer on the side surface of the N-type doping layer and the surface of the second intrinsic layer away from the silicon substrate; The second P-type doped layer is prepared on the side surface of the first P-type doped layer and on the surface away from the second intrinsic layer; The third P-type doped layer is prepared on the side surface of the second P-type doped layer and on the surface away from the first P-type doped layer; A first transparent conductive film layer is prepared on the surface of the N-type doped layer away from the first intrinsic layer; A second transparent conductive film layer is prepared on the surface of the third P-type doped layer away from the second P-type doped layer.

[0029] In the third aspect of the present application, a photovoltaic module is provided, including the solar cell described above, and / or a solar cell prepared by the preparation method of the solar cell described above. Thus, the photovoltaic module has good electrochemical performance and a high conversion efficiency. Description of the Drawings

[0030] Figure 1 is a schematic structural diagram of a solar cell according to an embodiment of the present application; Figure 2 is a schematic structural diagram of a solar cell according to another embodiment of the present application.

[0031] Description of the Reference Numerals: Solar cell 100; silicon substrate 10; first intrinsic layer 21; N-type doped layer 31; first transparent conductive film layer 41; second intrinsic layer 22; P-type doped layer 32; first P-type doped layer 321; second P-type doped layer 322; third P-type doped layer 323; second transparent conductive film layer 42. Detailed Description of the Embodiments

[0032] The embodiments of the present application will be described in detail below. The examples of the embodiments are shown in the drawings. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present application and should not be construed as limiting the present application.

[0033] The present application is based on the inventor's discovery and recognition of the following facts and problems: In related technologies, in order to optimize the optical response of heterojunction solar cells and reduce the parasitic absorption of amorphous silicon and microcrystalline silicon, N-type and P-type doped microcrystalline silicon oxides are mostly used as the window, intermediate reflection layer, etc. of heterojunction cells. Microcrystalline silicon oxide has adjustable refractive index, low absorption coefficient and sufficient conductivity, effectively reducing parasitic absorption. The optical properties of the doped film layer are strongly correlated with the oxygen content. Although increasing the oxygen content can increase the band gap of the doped film layer, reduce the refractive index and significantly improve the light transmittance, however, with the increase of the oxygen content, the conductivity shows a downward trend. On the other hand, the increase of the oxygen content will lead to a lower fill factor of the battery. This is because at the interface of the transparent conductive film layer / P-type microcrystalline silicon oxide emitter on the back of the battery, the holes generated by the silicon substrate must pass through the amorphous and microcrystalline materials and recombine with the electrons of the N-type high doping again. However, the mismatch of the adjacent band edges at the interface will generate a potential barrier at the interface. Therefore, in order to obtain a high hole tunneling probability, the potential barrier at the interface must be narrow enough, that is, there must be a high enough doping density in the emitter to increase the electric field strength in this region to increase the tunneling probability. And the effective doping density of P-type doped microcrystalline silicon oxide decreases with the increase of the oxygen content, resulting in a decrease in conductivity. The low effective doping rate of microcrystalline silicon oxide results in less effective hole tunneling at the interface and increases the back contact. To sum up, for the hole carrier transport on the back, the increase of the hole tunneling through the interface potential barrier of microcrystalline silicon oxide and the transparent conductive film layer affects the improvement of the battery efficiency. In view of this, the present application designs a composite P-type doping layer for solar cells, which can improve the hole carrier transport and thus improve the conversion efficiency of the battery.

[0034] In the first aspect of the present application, a solar cell is provided. According to an embodiment of the present application, referring to Figure 1 , the solar cell 100 includes: A silicon substrate 10; the silicon substrate 10 has a first surface and a second surface which are oppositely arranged; A first intrinsic layer 21, an N-type doping layer 31 and a first transparent conductive film layer 41 which are sequentially arranged on the first surface of the silicon substrate 10; A second intrinsic layer 22, a P-type doping layer 32 and a second transparent conductive film layer 42 which are sequentially arranged on the second surface of the silicon substrate 10; The P-type doping layer 32 includes a first P-type doping layer 321, a second P-type doping layer 322 and a third P-type doping layer 323 which are sequentially arranged; The first P-type doping layer 321 is in contact with the second intrinsic layer 22; The oxygen doping concentration of the third P-type doping layer 323 < the oxygen doping concentration of the second P-type doping layer 322 ≤ the oxygen doping concentration of the first P-type doping layer 321; The boron doping concentration of the third P-type doping layer 323 ≥ the boron doping concentration of the second P-type doping layer 322 > the boron doping concentration of the first P-type doping layer 321; The boron doping concentration of the first P-type doping layer is 0 to 1×10 5 cm -3 .

[0035] In this application, while designing the first P-type doping layer, the second P-type doping layer and the third P-type doping layer in the solar cell, the magnitude relationship between the oxygen doping concentration and the boron doping concentration of the three P-type doping layers is set. Among them, the first P-type doping layer has a relatively high oxygen doping concentration and a relatively low boron doping concentration. The relatively low boron doping concentration can prevent boron in the subsequent second P-type doping layer or third P-type doping layer from entering the second intrinsic layer and affecting the passivation effect of the second intrinsic layer; compared with the first P-type doping layer, the oxygen doping concentration of the second P-type doping layer is reduced, which can improve the light transmittance of the battery and also improve hole transport. Compared with the first P-type doping layer, the boron doping concentration of the second P-type doping layer is increased, which can establish a hole conduction network and thus improve the conversion efficiency of the battery; the third P-type doping layer has the highest boron doping concentration, which can improve the contact with the second transparent conductive film layer and increase the probability of back surface hole tunneling. Therefore, the solar cell of this application can enhance the transport of carriers, reduce the hole contact barrier, and significantly improve the conversion efficiency of the battery.

[0036] In some embodiments, the ratio of the oxygen doping concentration of the first P-type doping layer to the oxygen doping concentration of the second P-type doping layer is (1~1000):1. As an example, the ratio of the oxygen doping concentration of the first P-type doping layer to the oxygen doping concentration of the second P-type doping layer can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1, 500:1, 1000:1. Thus, the conversion efficiency of the battery can be further improved.

[0037] In some embodiments, the ratio of the boron doping concentration of the second P-type doping layer to the boron doping concentration of the third P-type doping layer is 1:(1~100). As an example, the ratio of the boron doping concentration of the second P-type doping layer to the boron doping concentration of the third P-type doping layer can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90, 1:100. Thus, the conversion efficiency of the battery can be further improved.

[0038] In some embodiments, the oxygen doping concentration of the first P-type doping layer is 1×10 20 cm -3 ~1×10 22 cm -3。For example, the oxygen doping concentration of the first P-type doping layer can be 1×10 20 cm -3 、2×10 20 cm -3 、3×10 20 cm -3 、4×10 20 cm -3 、5×10 20 cm -3 、6×10 20 cm -3 、7×10 20 cm -3 、8×10 20 cm -3 、9×10 20 cm -3 、1×10 21 cm -3 、2×10 21 cm -3 、3×10 21 cm -3 、4×10 21 cm -3 、5×10 21 cm -3 、6×10 21 cm -3 、7×10 21 cm -3 、8×10 21 cm -3 、9×10 21 cm -3 、1×10 22 cm -3 。Thus, the microcrystal nucleation can be further promoted, and the carrier transport barrier can be reduced.

[0039] In some embodiments, for example, the boron doping concentration of the first P-type doping layer is 0, 10 cm -3 、50 cm -3 、100cm -3 、500 cm -3 、1×10 3 cm -3 、2×10 3 cm -3 、3×10 3 cm -3 、4×10 3 cm -3 、5×10 3 cm -3 、6×10 3 cm -3, 7×10 3 cm -3 , 8×10 3 cm -3 , 9×10 3 cm -3 , 1×10 4 cm -3 , 2×10 4 cm -3 , 3×10 4 cm -3 , 4×10 4 cm -3 , 5×10 4 cm -3 , 6×10 4 cm -3 , 7×10 4 cm -3 , 8×10 4 cm -3 , 9×10 4 cm -3 , 1×10 5 cm -3 . Thus, the entry of boron in the second P-type doping layer and the third P-type doping layer into the second intrinsic layer can be further reduced, affecting its passivation effect.

[0040] In some embodiments, the oxygen doping concentration of the second P-type doping layer is 1×10 19 cm -3 ~1×10 20 cm -3 . As an example, the oxygen doping concentration of the second P-type doping layer is 1×10 19 cm -3 , 2×10 19 cm -3 , 3×10 19 cm -3 , 4×10 19 cm -3 , 5×10 19 cm -3 , 6×10 19 cm -3 , 7×10 19 cm -3 , 8×10 19 cm -3 , 9×10 19 cm -3 , 1×10 20 cm -3 . Thus, in the second P-type doping layer, moderate oxygen doping has a wide bandgap, improving the light transmittance of microcrystalline silicon, and thus enhancing the conversion efficiency of the battery.

[0041] In some embodiments, the boron doping concentration of the second P-type doping layer is 1×10 19 cm -3 ~1×10 20 cm -3 . As an example, the boron doping concentration of the second P-type doping layer is 1×10 19 cm -3 , 2×10 19 cm -3 , 3×10 19 cm -3 , 4×10 19 cm -3 , 5×10 19 cm -3 , 6×10 19 cm -3 , 7×10 19 cm -3 , 8×10 19 cm -3 , 9×10 19 cm -3 , 1×10 20 cm -3 . Thus, in the second P-type doping layer, appropriate boron doping can establish a hole conduction network, thereby improving the conversion efficiency of the battery.

[0042] In some embodiments, the oxygen doping concentration of the third P-type doping layer is 0~1×10 12 cm -3 . As an example, the oxygen doping concentration of the third P-type doping layer can be 0, 10 cm -3 , 100 cm -3 , 1000 cm -3 , 1×10 4 cm -3 , 1×10 5 cm -3 , 1×10 6 cm -3 , 1×10 7 cm -3 , 1×10 8 cm -3 , 1×10 9 cm -3 , 1×10 10 cm -3 , 1×10 11 cm -3 , 1×10 12 cm -3When the oxygen doping concentration in the third P-type doping layer is 0, the passivation effect of the third P-type doping layer can be improved. When a certain concentration of oxygen is doped in the third P-type doping layer, Si-O bonds can be formed with silicon (Si) in the amorphous silicon, reducing the interface state density and suppressing carrier recombination.

[0043] In some embodiments, the boron doping concentration of the third P-type doping layer is 1×10 20 cm -3 ~1×10 21 cm -3 . As an example, the boron doping concentration of the third P-type doping layer can be 1×10 20 cm -3 、2×10 20 cm -3 、3×10 20 cm -3 、4×10 20 cm -3 、5×10 20 cm -3 、6×10 20 cm -3 、7×10 20 cm -3 、8×10 20 cm -3 、9×10 20 cm -3 、1×10 21 cm -3 High boron doping in the third P-type doping layer can narrow the space charge region, enhance the electric field strength and tunneling probability, improve the contact, and increase the conversion efficiency of the battery.

[0044] In some embodiments, the thickness ratio of the first P-type doping layer, the second P-type doping layer, and the third P-type doping layer is 1:(10~25):(1~5). As an example, the thickness ratio of the first P-type doping layer, the second P-type doping layer, and the third P-type doping layer can be 1:10:1, 1:15:1, 1:20:1, 1:25:1, 1:10:3, 1:15:3, 1:20:3, 1:25:3, 1:10:5, 1:15:5, 1:20:5, 1:25:5. Thus, controlling the ratio of the thicknesses of the first P-type doping layer, the second P-type doping layer, and the third P-type doping layer can improve the hole carrier transport and contact characteristics, and increase the conversion efficiency of the battery.

[0045] In some embodiments, the thickness of the first P-type doped layer is 1 nm to 2 nm. As an example, the thickness of the first P-type doped layer is 1 nm, 1.1 nm, 1.2 nm, 1.3 nm, 1.4 nm, 1.5 nm, 1.6 nm, 1.7 nm, 1.8 nm, 1.9 nm, 2 nm. The first P-type doped layer with the above thickness can reduce carriers, lower the interface barrier with adjacent layers (such as the intrinsic amorphous silicon layer or the intrinsic silicon oxide layer), promote carrier tunneling, reduce contact resistance, and improve the conversion efficiency of the battery.

[0046] In some embodiments, the thickness of the second P-type doped layer is 20 nm to 25 nm. As an example, the thickness of the second P-type doped layer is 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm. Thus, the second P-type doped layer with the above thickness can ensure the carrier transport path, provide more carrier transport channels, and further improve the conversion efficiency of the battery.

[0047] In some embodiments, the thickness of the third P-type doped layer is 3 nm to 5 nm. As an example, the thickness of the third P-type doped layer is 3 nm, 3.5 nm, 4 nm, 4.5 nm, 5 nm. Since the boron doping concentration of the third P-type doped layer is the highest, controlling its thickness within the above range can reduce carriers, lower the interface barrier with adjacent layers (such as the transparent oxide film layer), promote carrier tunneling, reduce contact resistance, and improve the conversion efficiency of the battery.

[0048] In some embodiments, the first P-type doped layer, the second P-type doped layer, and the third P-type doped layer each independently include a P-type amorphous silicon layer, a P-type microcrystalline silicon layer, or a composite layer of the two. The higher oxygen doping concentration in the first P-type doped layer can provide nucleation sites for subsequent microcrystalline silicon growth, facilitate microcrystal nucleation, and reduce the carrier transport barrier.

[0049] In some embodiments, each film layer is gradually formed. During the coating process of each film layer, the film layer material will wrap around the side of the silicon substrate to form a morphology such as Figure 2 As shown in Figure 2 , the first P-type doped layer 321 overlaps with the N-type doped layer 31 on the side of the silicon substrate 10, and the first P-type doped layer 321 is disposed outside the N-type doped layer 31. Specifically, the outside of the N-type doped layer 31 is the side away from the silicon substrate 10. Thus, the first P-type doped layer can not only enhance the passivation effect of the second intrinsic layer on the side, but also isolate the N-type doped layer and the second P-type doped layer, improve the insulation of the side film layer, further reduce the battery leakage risk, and enhance the conversion efficiency of the battery.

[0050] In some embodiments, as shown in Figure 2As shown, a second intrinsic layer 22 is disposed on the second surface and the side surface of the silicon substrate 10; a first intrinsic layer 21 is disposed on the first surface of the silicon substrate 10 and the side surface of the second intrinsic layer 22; an N-type doped layer 31 is disposed on the side surface of the first intrinsic layer 21 and the surface of the first intrinsic layer 21 away from the silicon substrate 10; a first P-type doped layer 321 is disposed on the side surface of the N-type doped layer 31 and the surface of the second intrinsic layer 22 away from the silicon substrate 10; a second P-type doped layer 322 is disposed on the side surface of the first P-type doped layer 321 and the surface of the first P-type doped layer 321 away from the second intrinsic layer 22; a third P-type doped layer 323 is disposed on the side surface of the second P-type doped layer 322 and the surface of the second P-type doped layer 322 away from the first P-type doped layer 321.

[0051] In some embodiments, the N-type doped layer includes an N-type amorphous silicon layer, an N-type microcrystalline silicon layer, or a composite layer of the two.

[0052] In some embodiments, the thickness of the N-type doped layer is 1 nm to 50 nm. As an example, the thickness of the N-type doped layer is 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm.

[0053] In some embodiments, the first intrinsic layer may be an intrinsic amorphous silicon layer or an intrinsic amorphous silicon oxide layer.

[0054] In some embodiments, the thickness of the first intrinsic layer is 1 nm to 20 nm. As an example, the thickness of the first intrinsic layer is 1 nm, 5 nm, 10 nm, 15 nm, 20 nm.

[0055] In some embodiments, the second intrinsic layer may be an intrinsic amorphous silicon layer or an intrinsic amorphous silicon oxide layer.

[0056] In some embodiments, the thickness of the second intrinsic layer is 1 nm to 20 nm. As an example, the thickness of the second intrinsic layer is 1 nm, 5 nm, 10 nm, 15 nm, 20 nm.

[0057] It can be understood that the materials and deposition thicknesses of the first intrinsic layer and the second intrinsic layer may be the same or different. The specific materials and deposition thicknesses can be adaptively adjusted according to actual process requirements.

[0058] In some embodiments, the material of the first transparent conductive film layer includes one or more of indium tin oxide (ITO), indium oxide doped with lanthanide metals, fluorine-doped tin oxide (FTO), antimony-doped tin oxide, boron-doped zinc oxide (BZO), aluminum zinc oxide (AZO), indium zinc oxide (IZO), gallium zinc oxide (GZO), indium tungsten oxide (IWO).

[0059] In some embodiments, the thickness of the first transparent conductive film layer is 50 nm to 150 nm. As an example, the thickness of the first transparent conductive film layer is 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm.

[0060] In some embodiments, the material of the second transparent conductive film layer includes one or more of indium tin oxide (ITO), lanthanide metal-doped indium oxide, fluorine-doped tin oxide (FTO), antimony-doped tin oxide, boron-doped zinc oxide (BZO), aluminum zinc oxide (AZO), indium zinc oxide (IZO), gallium zinc oxide (GZO), indium tungsten oxide (IWO).

[0061] It can be understood that the materials of the first transparent conductive film layer and the second transparent conductive film layer can be the same material or different materials.

[0062] In some embodiments, the thickness of the second transparent conductive film layer is 50 nm to 150 nm. As an example, the thickness of the second transparent conductive film layer is 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm.

[0063] In some embodiments, the solar cell further includes a first metal electrode, and the first metal electrode is disposed on a side of the first transparent conductive film layer away from the N-type doped layer.

[0064] In some embodiments, the first metal electrode includes one or more of Al, Ti, Ni, Co, Ag, Cu, and Sn.

[0065] In some embodiments, the solar cell further includes a second metal electrode, and the second metal electrode is disposed on a side of the second transparent conductive film layer away from the P-type doped layer.

[0066] In some embodiments, the second metal electrode includes one or more of Al, Ti, Ni, Co, Ag, Cu, and Sn.

[0067] In some embodiments, the thickness of the silicon substrate is 50 μm to 200 μm. As an example, the thickness of the silicon substrate is 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm.

[0068] In some embodiments, the first surface is the main light-receiving surface, and the second surface is the secondary light-receiving surface.

[0069] In some embodiments, the conductivity type of the silicon substrate is N-type, and a PN junction is formed on the secondary light-receiving surface.

[0070] In the second aspect of the present application, a method for preparing the above solar cell is provided, including the following steps: S100. Prepare a first intrinsic layer, an N-type doped layer, and a first transparent conductive film layer in sequence on the first surface of the silicon substrate.

[0071] The present application does not particularly limit the specific type and size (such as thickness, diameter, etc.) of the silicon substrate, which can be selected according to actual needs. As an example, the silicon substrate can be an N-type monocrystalline silicon wafer, and the thickness can be 50 μm to 200 μm (specifically, such as 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, etc.).

[0072] It can be understood that the silicon substrate of the present application can be a double-sided polished and clean silicon substrate obtained after completing double-sided cleaning and polishing, removing surface organic substances, metal impurities, and surface damage layers, etc.

[0073] The present application does not specifically limit the process for cleaning the silicon substrate, which can be any cleaning process, such as Standard Clean 1 or Standard Clean 2; among them, Standard Clean 1 can include a mixture of ammonium hydroxide, hydrogen peroxide, and water, and Standard Clean 2 can include a mixture of hydrochloric acid, hydrogen peroxide, and water.

[0074] In some embodiments, the double-sided polished and clean silicon substrate can be textured. Specifically, texturing refers to forming a microscopic textured surface structure on the silicon substrate by chemical etching or physical methods. This structure can increase the residence time of light on the silicon surface and reduce light reflection, thereby improving the light absorption efficiency.

[0075] In some embodiments, texturing can be performed by chemical etching using an alkaline solution (such as sodium hydroxide or potassium hydroxide). Utilizing the anisotropic etching characteristics of silicon in the alkaline solution, a pyramidal textured surface structure is formed.

[0076] In some embodiments, the first intrinsic layer can be prepared by plasma-enhanced chemical vapor deposition (PECVD), hot-wire chemical vapor deposition (HWCVD), or low-pressure chemical vapor deposition (LPCVD).

[0077] In some embodiments, the N-type doped layer can be prepared by plasma-enhanced chemical vapor deposition, hot-wire chemical vapor deposition, or low-pressure chemical vapor deposition.

[0078] In some embodiments, the method for manufacturing a solar cell further includes: preparing a first metal electrode on a side of the first transparent conductive film layer away from the N-type doped layer.

[0079] In some embodiments, the first transparent conductive film layer can be prepared by atmospheric pressure chemical vapor deposition (APCVD), radio frequency magnetron sputtering (PVD), or reactive plasma deposition (RPD).

[0080] In some embodiments, the first metal electrode can be prepared by screen printing, laser transfer of low-temperature silver paste, low-temperature copper paste, or silver-coated copper paste; or, the first metal electrode can be prepared by electroplating one or more of Al, Ti, Ni, Co, Ag, Cu, and Sn.

[0081] S200. Sequentially prepare a second intrinsic layer, a P-type doped layer, and a second transparent conductive film layer on the second surface of the silicon substrate; Preparing the first P-type doped layer includes: performing a first doping process on a surface of the second intrinsic layer away from the silicon substrate to obtain the first P-type doped layer; Preparing the second P-type doped layer includes: performing a second doping process on a surface of the first P-type doped layer away from the second intrinsic layer to obtain the second P-type doped layer; Preparing the third P-type doped layer includes: performing a third doping process on a surface of the second P-type doped layer away from the first P-type doped layer to obtain the third P-type doped layer.

[0082] In some embodiments, H2, silane, and an oxygen source are introduced in the first doping process.

[0083] In some embodiments, in the first doping process, the flow rate ratio of H2, silane, and the oxygen source is (250~600):1:(1~4). By optimizing the conditions of the first doping, the oxygen doping concentration and boron doping concentration of the first P-type doped layer, as well as the thickness of the first P-type doped layer, can be effectively regulated to obtain a solar cell with high conversion efficiency.

[0084] In some embodiments, the silane includes one or more of SiH4, Si2H6, and Si3H8; the oxygen source includes one or more of CO2, O2, and N2O.

[0085] In some embodiments, the first doping treatment includes: introducing hydrogen at a flow rate of 20,000 - 30,000 sccm, silane at a flow rate of 50 - 80 sccm, and CO2 and / or N2O at a flow rate of 100 - 200 sccm under the conditions of 140 - 160 °C and 4 - 6 Torr; the time of the first doping treatment is 10 - 20 s. Thus, the hole carrier transport can be further improved and the conversion efficiency of the battery can be increased.

[0086] As an example, the temperature of the first doping treatment can be 140, 145, 150, 155, 160 °C, the pressure can be 4, 4.5, 5, 5.5, 6 Torr, the flow rate of hydrogen can be 20,000, 21,000, 22,000, 23,000, 24,000, 25,000, 26,000, 27,000, 28,000, 29,000, 30,000 sccm, the flow rate of silane can be 50, 55, 60, 65, 70, 75, 80 sccm, and the flow rate of CO2 and / or N2O can be 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200 sccm.

[0087] In some embodiments, the first P-type doping layer can be prepared by plasma-enhanced chemical vapor deposition, hot-wire chemical vapor deposition, or low-pressure chemical vapor deposition.

[0088] In some embodiments, the power for preparing the first P-type doping layer is 4000 - 5000 W. As an example, the power for depositing the first P-type doping layer can be 4000, 4100, 4200, 4300, 4400, 4500, 4600, 4700, 4800, 4900, 5000 W.

[0089] In some embodiments, H2, silane, an oxygen source, and a boron source are introduced in the second doping treatment.

[0090] In some embodiments, in the second doping treatment, the flow rate ratio of H2, silane, the oxygen source, and the boron source is (200 - 500) : 1 : (0.1 - 1) : (0.2 - 1). By optimizing the conditions of the second doping, the oxygen doping concentration and boron doping concentration of the second P-type doping layer, as well as the thickness of the second P-type doping layer, can be effectively controlled, and a solar cell with high conversion efficiency can be obtained.

[0091] In some embodiments, the boron source includes one or more of BH3, B3H6, B4H 10 as described above, and the specific components of silane and the oxygen source in the second doping treatment are as described above and will not be elaborated here.

[0092] In some embodiments, the second doping treatment includes: introducing hydrogen at a flow rate of 20,000 - 25,000 sccm, silane at a flow rate of 50 - 100 sccm, CO2 and / or N2O at a flow rate of 10 - 30 sccm, and borane at a flow rate of 20 - 50 sccm under the conditions of 140 - 160 °C and 4 - 6 Torr; the time of the second doping treatment is 100 - 200 s. Thereby, the hole carrier transport can be further improved and the conversion efficiency of the battery can be increased.

[0093] As an example, the temperature of the second doping treatment can be 140, 145, 150, 155, 160 °C, the pressure can be 4, 4.5, 5, 5.5, 6 Torr, the flow rate of hydrogen can be 20,000, 21,000, 22,000, 23,000, 24,000, 25,000 sccm, the flow rate of silane can be 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100 sccm, the flow rate of CO2 and / or N2O can be 10, 15, 20, 25, 30 sccm, and the flow rate of borane can be 20, 25, 30, 35, 40, 45, 50 sccm.

[0094] In some embodiments, the second P-type doping layer can be prepared by plasma-enhanced chemical vapor deposition, hot-wire chemical vapor deposition, or low-pressure chemical vapor deposition.

[0095] In some embodiments, the power for depositing the second P-type doping layer is 5000 - 7000 W. As an example, the power for depositing the second P-type doping layer is 5000, 5100, 5200, 5300, 5400, 5500, 5600, 5700, 5800, 5900, 6000, 6100, 6200, 6300, 6400, 6500, 6600, 6700, 6800, 6900, 7000 W.

[0096] In some embodiments, one or more of H2, silane, an oxygen source, and a boron source are introduced in the third doping treatment.

[0097] In some embodiments, H2, silane, and a boron source are introduced in the third doping treatment.

[0098] In other embodiments, H2, silane, an oxygen source, and a boron source are introduced in the third doping treatment.

[0099] In some embodiments, the flow rate of the oxygen source in the third doping treatment < the flow rate of the oxygen source in the second doping treatment ≤ the flow rate of the oxygen source in the first doping treatment; the flow rate of the boron source in the third doping treatment ≥ the flow rate of the boron source in the second doping treatment > the flow rate of the boron source in the first doping treatment. Thus, the hole carrier transport can be further improved and the conversion efficiency of the battery can be increased.

[0100] In some embodiments, in the third doping treatment, the flow rate ratio of H2, silane, and boron source is (200 - 500):1:(0.2 - 4). By optimizing the conditions of the third doping, the oxygen doping concentration, boron doping concentration, and thickness of the third P-type doping layer can be effectively regulated, and a solar cell with high conversion efficiency can be obtained. In addition, in the third doping treatment, oxygen can form Si-O bonds with silicon (Si) in amorphous silicon, reducing the interface state density and suppressing carrier recombination; the third P-type doping layer prepared under the condition of no oxygen source has fewer defect states and a higher electron tunneling probability, and is in direct contact with the second transparent conductive film layer, which can avoid the potential barrier caused by oxygen and reduce the contact resistance.

[0101] The specific components of silane, oxygen source, and boron source in the third doping treatment are as described above and will not be elaborated here.

[0102] In some embodiments, the third doping treatment includes: introducing hydrogen at a flow rate of 20000 - 25000 sccm, silane at a flow rate of 50 - 100 sccm, CO2 and / or N2O at a flow rate of 0 - 30 sccm, and borane at a flow rate of 20 - 200 sccm under the conditions of 140 - 160 °C and 4 - 6 Torr; the time of the third doping treatment is 30 - 60 s. Thus, the hole carrier transport can be further improved and the conversion efficiency of the battery can be increased.

[0103] As an example, the temperature of the third doping treatment can be 140, 145, 150, 155, 160 °C, the pressure can be 4, 4.5, 5, 5.5, 6 Torr, the flow rate of hydrogen can be 20000, 21000, 22000, 23000, 24000, 25000 sccm, the flow rate of silane can be 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100 sccm, and the flow rate of borane can be 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200 sccm.

[0104] In some embodiments, the third P-type doping layer can be prepared by plasma-enhanced chemical vapor deposition, hot-wire chemical vapor deposition, or low-pressure chemical vapor deposition.

[0105] In some embodiments, the power for depositing the third P-type doping layer is 5000 - 7000 W. As an example, the power for depositing the third P-type doping layer is 5000, 5100, 5200, 5300, 5400, 5500, 5600, 5700, 5800, 5900, 6000, 6100, 6200, 6300, 6400, 6500, 6600, 6700, 6800, 6900, 7000 W.

[0106] In some embodiments, the second intrinsic layer can be prepared by plasma enhanced chemical vapor deposition, hot wire chemical vapor deposition, or low pressure chemical vapor deposition.

[0107] In some embodiments, a method for manufacturing a solar cell includes the following steps: The second intrinsic layer is prepared on the second surface of the silicon substrate, then the first intrinsic layer is prepared on the first surface of the silicon substrate, the N-type doping layer is prepared on the side of the first intrinsic layer away from the silicon substrate, and the P-type doping layer is prepared on the side of the second intrinsic layer away from the silicon substrate.

[0108] In some embodiments, a method for manufacturing a solar cell specifically includes the following steps: The second intrinsic layer is prepared on the second surface and the side surface of the silicon substrate; The first intrinsic layer is prepared on the first surface of the silicon substrate and the side surface of the second intrinsic layer; The N-type doping layer is prepared on the side surface of the first intrinsic layer and the surface away from the silicon substrate; The first P-type doping layer is prepared on the side surface of the N-type doping layer and the surface of the second intrinsic layer away from the silicon substrate; The second P-type doping layer is prepared on the side surface of the first P-type doping layer and the surface away from the second intrinsic layer; The third P-type doping layer is prepared on the side surface of the second P-type doping layer and the surface away from the first P-type doping layer; The first transparent conductive film layer is prepared on the surface of the N-type doping layer away from the first intrinsic layer; The second transparent conductive film layer is prepared on the surface of the third P-type doping layer away from the second P-type doping layer.

[0109] During the coating process of each film layer, the film layer material will also wrap around the side of the silicon substrate. According to the process, different film layer stacking relationships will be formed on the side. Specifically, when using an N-type silicon substrate, the first surface of the silicon substrate is the front surface (the main light-receiving surface), and the second surface of the silicon substrate is the back surface (the secondary light-receiving surface). In this structure, the PN junction is formed on the back of the battery, and the high-low junction (N-N+) is formed on the front of the battery. The present application designs a specific process sequence. The first step is to form a layer of protection on the back, then form the key film layer on the front, and finally form the back PN junction, which can further improve the edge leakage phenomenon.

[0110] In some embodiments, the method for preparing a solar cell further includes: preparing a second metal electrode on a side of the second transparent conductive film layer away from the P-type doping layer.

[0111] In some embodiments, the second transparent conductive film layer can be prepared by atmospheric pressure chemical vapor deposition, radio frequency magnetron sputtering, or reactive plasma deposition.

[0112] In some embodiments, the second metal electrode can be prepared by screen printing, laser transfer of low-temperature silver paste, low-temperature copper paste, or silver-coated copper paste; or, the second metal electrode can be prepared by electroplating one or more of Al, Ti, Ni, Co, Ag, Cu, and Sn.

[0113] In the third aspect of the present application, a photovoltaic module is provided, including the solar cell described above, and / or a solar cell prepared by the method for preparing the solar cell described above. Thus, the photovoltaic module has good electrochemical performance and a high conversion efficiency.

[0114] For the convenience of describing the technical solutions of the application, some concepts involved in the embodiments of the present application are described.

[0115] N-type: Also known as electron type. In an N-type semiconductor, free electrons are the majority carriers and holes are the minority carriers.

[0116] P-type: Also known as hole type. In a P-type semiconductor, holes are the majority carriers and free electrons are the minority carriers.

[0117] The embodiments of the present application are described in detail below.

[0118] The borane used in the embodiments of the present application is B2H6, and the silane is SiH4.

[0119] Embodiment 1 The method for preparing the solar cell of this embodiment includes the following steps: (1) Cleaning and texturing Select an N-type monocrystalline silicon wafer with a thickness of 150 μm, clean the front and back sides of the wafer through a trough-type cleaning and texturing machine, and then texture the wafer with a sodium hydroxide solution to form a textured surface on the front and back sides of the wafer.

[0120] (2)Prepare the intrinsic layer Prepare the intrinsic layer by plasma-enhanced chemical vapor deposition (PECVD); deposit the back intrinsic layer on the back side of the silicon wafer obtained in step (1), and the specific parameters are as follows: introduce hydrogen and silane. Prepare the intrinsic layer at 0.5 Torr, and control the thickness within 5 - 7 nm; the coating power is 200 W, the hydrogen flow rate ranges from 1500 sccm, and the silane flow rate ranges from 750 sccm; deposit a 6-nm-thick front intrinsic layer on the front side of the silicon wafer obtained in step (1), and refer to the preparation steps of the back intrinsic layer for the preparation parameters of the front intrinsic layer.

[0121] (3)Prepare the N-type doped layer Deposit a 25-nm-thick N-type doped layer on the front side of the silicon wafer obtained in step (2) by plasma-enhanced chemical vapor deposition (PECVD).

[0122] (4)Prepare the P-type doped layer Deposit the first P-type doped layer, the second P-type doped layer, and the third P-type doped layer on the back side of the silicon wafer obtained in step (3) in sequence by plasma-enhanced chemical vapor deposition (PECVD), and the specific parameters are as follows: Introduce hydrogen and silane, CO2 to prepare the first P-type doped layer, with a pressure of 5 Torr and a coating power of 4500 W; the hydrogen flow rate ranges from 25000 sccm, the silane flow rate ranges from 70 sccm, and the CO2 flow rate ranges from 150 sccm; the deposition temperature is 150 °C, the deposition time is 20 s, the thickness of the first P-type doped layer is 1 nm, and the oxygen doping concentration is 1×10 21 cm -3 , and the boron doping concentration is 0.

[0123] Introduce hydrogen and silane, CO2, borane to prepare the second P-type doped layer, with a pressure of 5 Torr and a coating power of 6000 W; the hydrogen flow rate ranges from 22000 sccm, the silane flow rate ranges from 75 sccm; the CO2 flow rate ranges from 20 sccm, and borane is 25 sccm; control the deposition temperature at 150 °C, the deposition time is 180 s, control the thickness of the second P-type doped layer at 20 nm, and the oxygen doping concentration is 1×10 19 cm -3 , and the boron doping concentration is 1×10 19 cm -3 .

[0124] Hydrogen, silane, and borane are introduced to prepare the third P-type doping layer at a pressure of 5 Torr and a coating power of 6000 W. The hydrogen flow rate ranges from 22000 sccm, the silane flow rate ranges from 75 sccm, and the borane flow rate ranges from 150 sccm. The deposition temperature is controlled at 150 °C, the deposition time is 40 s, the thickness of the third P-type doping layer is controlled at 3 nm, the oxygen doping concentration is 0, and the boron doping concentration is 1×10 20 cm -3 。

[0125] (5)Deposit indium tin oxide layer By magnetron sputtering, indium tin oxide (ITO) layers with a thickness of 100 nm are deposited on the front and back sides of the silicon wafer obtained in step (4).

[0126] (6)Prepare metal electrodes Silver metal electrodes are prepared on the indium tin oxide (ITO) layers on the front and back sides of the silicon wafer respectively.

[0127] Example 2 The preparation method of the solar cell in this example is only different from that in Example 1 in that: the preparation parameters of the first P-type doping layer in step (4) are adjusted in this example: the hydrogen flow rate ranges from 27500 sccm, and the silane flow rate ranges from 50 sccm. The oxygen doping concentration of the first P-type doping layer in this example is 1×10 21 cm -3 ,and the boron doping concentration is 0.

[0128] The remaining steps are carried out according to the method in Example 1.

[0129] Example 3 The preparation method of the solar cell in this example is only different from that in Example 1 in that: the preparation parameters of the third P-type doping layer in step (4) are adjusted in this example: the borane flow rate ranges from 180 sccm, and the CO2 flow rate ranges from 20 sccm. The oxygen doping concentration of the third P-type doping layer in this example is 1×10 10 cm -3 ,and the boron doping concentration is 1×10 21 cm -3 。

[0130] Example 4 The preparation method of the solar cell in this example is only different from that in Example 1 in that: the preparation parameters of the third P-type doping layer in step (4) are adjusted in this example: the borane flow rate ranges from 200 sccm, and the CO2 flow rate ranges from 20 sccm. The oxygen doping concentration of the third P-type doping layer in this example is 1×10 10 cm -3 ,and the boron doping concentration is 1×10 22 cm -3 。

[0131] Comparative Example 1 The preparation method of the solar cell in this comparative example is different from that of Example 1 in that step (4) is adjusted in this comparative example to: Hydrogen, silane, CO2, and borane are introduced into the back surface to prepare a doped microcrystalline silicon oxide layer. The pressure is 5 Torr, and the coating power is 6000 W; the hydrogen flow rate ranges from 25000 sccm, and the silane flow rate ranges from 75 sccm; the CO2 flow rate ranges from 20 sccm, and the borane is 60 sccm. The deposition temperature is controlled at 150 °C, and the film thickness of the doped microcrystalline silicon oxide layer is 32 nm.

[0132] The remaining steps are carried out according to the method in Example 1.

[0133] Test Example The solar cells obtained in the examples and comparative examples are tested.

[0134] Back surface hole tunneling contact resistivity: Tested using a TLM tester.

[0135] Short-circuit current (Isc): Tested using a silicon solar cell Sinton IV tester.

[0136] Fill factor (FF): Tested using a silicon solar cell Sinton IV tester.

[0137] Conversion efficiency (Eff): Tested using a silicon solar cell Sinton IV tester.

[0138] The experimental results are shown in Table 1.

[0139] Table 1

[0140] As can be seen from Table 1, compared with Comparative Example 1 that prepares a conventional single-layer P-type doping layer, Examples 1 to 4 of the present application are designed with three-layer P-type doping layers. From the electrical performance results, it can be seen that the short-circuit current of the battery in Comparative Example 1 is comparable to that of the examples of the present application. The batteries of Examples 1 to 4 of the present application have lower back surface hole tunneling contact resistivity, higher conversion efficiency, and fill factor.

[0141] By comparing Example 1 and Example 2, it can be seen that in Example 2, by increasing the hydrogen flow rate while decreasing the silane flow rate, finally, the fill factor of Example 2 is significantly improved, and the conversion efficiency is increased by 0.04%.

[0142] By comparing Example 1 with Examples 3 and 4, it can be seen that in the case of oxygen doping, it is necessary to increase the boron doping concentration to effectively improve the battery efficiency. It may be that the oxygen doping increases the density of film defect states, and it is necessary to increase the high boron doping to improve the hole contact.

[0143] In the description of this specification, the descriptions with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0144] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A solar cell, characterized in that, Comprising: A silicon substrate; The silicon substrate has a first surface and a second surface which are oppositely arranged; An intrinsic layer, an N-type doped layer, and a first transparent conductive film layer are sequentially arranged on the first surface of the silicon substrate; A second intrinsic layer, a P-type doped layer, and a second transparent conductive film layer are sequentially arranged on the second surface of the silicon substrate; The P-type doped layer includes a first P-type doped layer, a second P-type doped layer, and a third P-type doped layer which are sequentially arranged; The first P-type doped layer is in contact with the second intrinsic layer; The oxygen doping concentration of the third P-type doped layer < the oxygen doping concentration of the second P-type doped layer ≤ the oxygen doping concentration of the first P-type doped layer; The boron doping concentration of the third P-type doped layer ≥ the boron doping concentration of the second P-type doped layer > the boron doping concentration of the first P-type doped layer; The boron doping concentration of the first P-type doping layer is 0 to 1×10 5 cm -3 .

2. The solar cell according to claim 1, wherein The ratio of the oxygen doping concentration of the first P-type doped layer to the oxygen doping concentration of the second P-type doped layer is (1~1000):1; And / or, the ratio of the boron doping concentration of the second P-type doped layer to the boron doping concentration of the third P-type doped layer is 1:(1~100).

3. The solar cell according to claim 1, wherein, The oxygen doping concentration of the first P-type doping layer is 1×10 20 cm -3 ~1×10 22 cm -3 ; And / or, the oxygen doping concentration of the second P-type doping layer is 1×10 19 cm -3 ~1×10 20 cm -3 ; And / or, the boron doping concentration of the second P-type doping layer is 1×10 19 cm -3 ~1×10 20 cm -3 ; And / or, the oxygen doping concentration of the third P-type doping layer is 0 to 1×10 12 cm -3 ; And / or, the boron doping concentration of the third P-type doping layer is 1×10 20 cm -3 ~1×10 21 cm -3 .

4. The solar cell according to claim 1, characterized in that, The thickness ratio of the first P-type doped layer, the second P-type doped layer, and the third P-type doped layer is 1:(10~25):(1~5); 5. The solar cell according to claim 1, characterized in that, The thickness of the first P-type doped layer is 1nm~2nm; And / or, the thickness of the second P-type doped layer is 20nm~25nm; And / or, the thickness of the third P-type doped layer is 3nm~5nm.

6. The solar cell according to claim 1, characterized in that, The first P-type doped layer forms an overlap with the N-type doped layer on the side surface of the silicon substrate, and the first P-type doped layer is arranged outside the N-type doped layer.

7. The solar cell according to claim 1, characterized in that, The second intrinsic layer is arranged on the second surface and the side surface of the silicon substrate; The first intrinsic layer is arranged on the first surface of the silicon substrate and the side surface of the second intrinsic layer; The N-type doped layer is arranged on the side surface of the first intrinsic layer and the surface of the first intrinsic layer away from the silicon substrate; The first P-type doped layer is arranged on the side surface of the N-type doped layer and the surface of the second intrinsic layer away from the silicon substrate; The second P-type doped layer is arranged on the side surface of the first P-type doped layer and the surface of the first P-type doped layer away from the second intrinsic layer; The third P-type doped layer is arranged on the side surface of the second P-type doped layer and the surface of the second P-type doped layer away from the first P-type doped layer.

8. The solar cell according to claim 1, characterized in that, The first surface is the main light-receiving surface, and the second surface is the secondary light-receiving surface.

9. The solar cell according to claim 8, characterized in that, The conductive type of the silicon substrate is N-type, and a PN junction is formed on the secondary light-receiving surface.

10. The method for preparing a solar cell according to any one of claims 1 to 9, characterized in that, Including the following steps: Preparing an intrinsic layer, an N-type doped layer, and a first transparent conductive film layer on the first surface of the silicon substrate in sequence; Preparing a second intrinsic layer, a P-type doped layer, and a second transparent conductive film layer on the second surface of the silicon substrate in sequence; Preparing the first P-type doped layer includes: performing a first doping treatment on the surface of the second intrinsic layer away from the silicon substrate to obtain the first P-type doped layer; Preparing the second P-type doped layer includes: performing a second doping treatment on the surface of the first P-type doped layer away from the second intrinsic layer to obtain the second P-type doped layer; The preparation of the third P-type doped layer includes: performing a third doping treatment on the surface of the second P-type doped layer away from the first P-type doped layer to obtain the third P-type doped layer.

11. The method for preparing a solar cell according to claim 10, wherein In the first doping treatment, H2, silane, and an oxygen source are introduced; and / or, in the second doping treatment, H2, silane, an oxygen source, and a boron source are introduced; and / or, in the third doping treatment, one or more of H2, silane, an oxygen source, and a boron source are introduced.

12. The method for preparing a solar cell according to claim 11, wherein, The introduction amount of the oxygen source in the third doping treatment < the introduction amount of the oxygen source in the second doping treatment ≤ the introduction amount of the oxygen source in the first doping treatment; and / or, the introduction amount of the boron source in the third doping treatment ≥ the introduction amount of the boron source in the second doping treatment > the introduction amount of the boron source in the first doping treatment.

13. The manufacturing method of the solar cell according to claim 10, characterized in that, It includes the following steps: Preparing the second intrinsic layer on the second surface and the side surface of the silicon substrate; Preparing the first intrinsic layer on the first surface of the silicon substrate and the side surface of the second intrinsic layer; Preparing the N-type doped layer on the side surface of the first intrinsic layer and the surface away from the silicon substrate; Preparing the first P-type doped layer on the side surface of the N-type doped layer and the surface of the second intrinsic layer away from the silicon substrate; Preparing the second P-type doped layer on the side surface of the first P-type doped layer and the surface away from the second intrinsic layer; Preparing the third P-type doped layer on the side surface of the second P-type doped layer and the surface away from the first P-type doped layer; Preparing a first transparent conductive film layer on the surface of the N-type doped layer away from the first intrinsic layer; Preparing a second transparent conductive film layer on the surface of the third P-type doped layer away from the second P-type doped layer.

14. A photovoltaic module, characterized in that, It includes the solar cell according to any one of claims 1 to 9, and / or, the solar cell prepared by the preparation method according to any one of claims 10 to 13.

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