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; the second intrinsic layer, the P-type doped layer and the second transparent conductive film layer are sequentially arranged on the second surface; 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; the oxygen doping concentration of the third P-type doping layer is greater than the oxygen doping concentration of the second P-type doping layer and is less than or equal to the oxygen doping concentration of the first P-type doping layer; the boron doping concentration of the third P-type doping layer is larger than or equal to the boron doping concentration of the second P-type doping layer and larger than the boron doping concentration of the first P-type doping layer. 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

Cross Reference to Related Applications

[0001] This application is a divisional application of the Chinese Invention Patent Application with the application number 202510751237.1 and the application date of June 6, 2025, and the invention name of "Solar Cell and Preparation Method Thereof, and Photovoltaic Module". TECHNICAL FIELD

[0002] The present application relates to the technical field of solar cells, in particular to a solar cell and a preparation method thereof, and a photovoltaic module. BACKGROUND

[0003] Heterojunction solar cells (HJT) have high open-circuit voltage and high conversion efficiency, and have been widely concerned. 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 oxide are often used as the window and intermediate reflection layer of heterojunction cells. For the transport of hole carriers on the back surface, the hole tunneling through the interface potential barrier of microcrystalline silicon oxide and transparent conductive film layer is increased, which affects the improvement of cell efficiency. Therefore, the doped layer on the back surface of the HJT cell still needs to be improved. SUMMARY

[0004] The present application aims to at least partly solve one of the technical problems in the related art. To this end, the present application provides a solar cell with high conversion efficiency and a preparation method thereof, and a photovoltaic module.

[0005] In a first aspect, the present application provides a solar cell, comprising: a silicon substrate; the silicon substrate having a first surface and a second surface arranged oppositely; a first intrinsic layer, an N-type doped layer and a first transparent conductive film layer arranged successively on the first surface of the silicon substrate; a second intrinsic layer, a P-type doped layer and a second transparent conductive film layer arranged successively on the second surface of the silicon substrate; the P-type doped layer comprising a first P-type doped layer, a second P-type doped layer and a third P-type doped layer arranged successively; the first P-type doped layer being 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. In the solar cell, the first P-type doped layer, the second P-type doped layer and the third P-type doped layer are designed to have a size relationship of the oxygen doping concentration and the boron doping concentration of the three P-type doped layers, wherein the first P-type doped layer has a higher oxygen doping concentration and a lower boron doping concentration, the lower boron doping concentration can prevent boron in the subsequent second P-type doped layer or third P-type doped layer from entering the second intrinsic layer, thereby affecting the passivation effect of the second intrinsic layer; compared with the first P-type doped layer, the second P-type doped layer has a reduced oxygen doping concentration, which can improve the light transmittance of the cell and also improve the hole transport; compared with the first P-type doped layer, the second P-type doped layer has an increased boron doping concentration, which can establish a hole conduction network, thereby improving the conversion efficiency of the cell; the third P-type doped layer has the highest boron doping concentration, which can improve the contact with the second transparent conductive film layer and increase the probability of hole tunneling on the back surface. Thus, the solar cell of the present application can enhance the transport of carriers, reduce the hole contact barrier and significantly improve the conversion efficiency of the cell.

[0006] According to an embodiment of the present application, at least one of the first P-type doped layer, the second P-type doped layer and the third P-type doped layer comprises a P-type amorphous silicon layer, a P-type microcrystalline silicon layer or a composite layer of both.

[0007] According to an embodiment of the present application, 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.

[0008] According to an embodiment of the present application, 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).

[0009] According to an embodiment of the present application, the oxygen doping concentration of the first P-type doped layer is 1×10 20 cm -3 -1×10 22 cm -3 .

[0010] According to embodiments of the present application, the boron doping concentration of the first P-type doped layer is 0~1×10 5 cm -3 .

[0011] According to embodiments of the present application, the oxygen doping concentration of the second P-type doped layer is 1×10 19 cm -3 ~1×10 20 cm -3 .

[0012] According to embodiments of the present application, the boron doping concentration of the second P-type doped layer is 1×10 19 cm -3 ~1×10 20 cm -3 .

[0013] According to embodiments of the present application, the oxygen doping concentration of the third P-type doped layer is 0~1×10 12 cm -3 .

[0014] According to embodiments of the present application, the boron doping concentration of the third P-type doped layer is 1×10 20 cm -3 ~1×10 21 cm -3 .

[0015] According to embodiments of the present application, 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).

[0016] According to embodiments of the present application, the thickness of the first P-type doped layer is 1nm~2nm.

[0017] According to embodiments of the present application, the thickness of the second P-type doped layer is 20nm~25nm.

[0018] According to embodiments of the present application, the thickness of the third P-type doped layer is 3nm~5nm.

[0019] According to embodiments of the present application, the first P-type doped layer forms an overlap with the N-type doped layer at the side surface of the silicon substrate, and the first P-type doped layer is arranged outside the N-type doped layer.

[0020] According to embodiments of the present application, the second intrinsic layer is arranged at the second surface and the side surface of the silicon substrate; the first intrinsic layer is arranged at the first surface of the silicon substrate and the side surface of the second intrinsic layer; The N-type doped layer is arranged at the side 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 at the side 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 at the side of the first P-type doped layer and the surface of the second P-type doped layer away from the first P-type doped layer. The third P-type doped layer is arranged at the side 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.

[0021] According to the embodiments of the present application, the first surface is a main light-receiving surface, and the second surface is a secondary light-receiving surface.

[0022] According to the embodiments of the present application, the silicon substrate is of N-type, and a PN junction is formed at the secondary light-receiving surface.

[0023] According to the embodiments of the present application, the N-type doped layer comprises an N-type amorphous silicon layer, an N-type microcrystalline silicon layer, or a composite layer of both.

[0024] In the second aspect of the present application, a preparation method of a solar cell is provided, comprising the following steps: A first intrinsic layer, an N-type doped layer, and a first transparent conductive film layer are sequentially prepared 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 prepared on the second surface of the silicon substrate; The step of preparing the first P-type doped layer comprises: 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; The step of preparing the second P-type doped layer comprises: 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 step of preparing the third P-type doped layer comprises: 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.

[0025] The method of the present application has simple preparation process, low cost, and can prepare a solar cell with high conversion efficiency.

[0026] According to the embodiments of the present application, H2, silane, and an oxygen source are introduced in the first doping treatment.

[0027] According to the embodiments of the present application, H2, silane, an oxygen source, and a boron source are introduced in the second doping treatment.

[0028] According to embodiments of the present application, one or more of H2, silane, an oxygen source and a boron source are introduced in the third doping process.

[0029] According to embodiments of the present application, the amount of oxygen source introduced in the third doping process is < the amount of oxygen source introduced in the second doping process ≤ the amount of oxygen source introduced in the first doping process.

[0030] According to embodiments of the present application, the amount of oxygen source introduced in the third doping process is greater than the amount of oxygen source introduced in the first doping process.

[0031] According to embodiments of the present application, the amount of boron source introduced in the third doping process is ≥ the amount of boron source introduced in the second doping process > the amount of boron source introduced in the first doping process.

[0032] According to embodiments of the present application, in the first doping process, the flow rate ratio of H2, silane and oxygen source introduced is (250-600):1:(1-4).

[0033] According to embodiments of the present application, in the second doping process, the flow rate ratio of H2, silane, oxygen source and boron source introduced is (200-500):1:(0.1-1):(0.2-1).

[0034] According to embodiments of the present application, in the third doping process, the flow rate ratio of H2, silane and boron source introduced is (200-500):1:(0.2-4).

[0035] According to embodiments of the present application, the method for preparing a solar cell comprises the following steps: preparing the second intrinsic layer on the second surface and 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 away from the second intrinsic layer of 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.

[0036] In a third aspect, the present application provides a photovoltaic module comprising the solar cell according to any one of the above aspects, and / or the solar cell prepared by the method according to any one of the above aspects. Thus, the photovoltaic module has good electrochemical performance and high conversion efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 FIG. 1 is a structural schematic diagram of a solar cell according to an embodiment of the present application; Figure 2 FIG. 2 is a structural schematic diagram of a solar cell according to another embodiment of the present application.

[0038] BRIEF DESCRIPTION OF DRAWINGS 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

[0039] Embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present application, and should not be understood as limiting the present application.

[0040] The present application is based on the discovery and realization of the inventors on the following facts and problems: In the related art, in order to optimize the optical response of the heterojunction solar cell, reduce the parasitic absorption of amorphous silicon and microcrystalline silicon, N-type and P-type doped microcrystalline silicon oxide is often used as the window layer and the intermediate reflection layer of the heterojunction solar cell. Microcrystalline silicon oxide has adjustable refractive index, low absorption coefficient and sufficient conductivity, which effectively reduces the parasitic absorption. The optical properties of the doped film layer are strongly related to 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, the conductivity decreases with the increase of the oxygen content. On the other hand, the increase of the oxygen content will lead to a low fill factor of the cell, because at the interface between the transparent conductive film layer and the P-type microcrystalline silicon oxide emitter on the back of the cell, the holes generated in the silicon substrate must pass through the amorphous and microcrystalline materials and recombine with the N-type highly doped electrons, but the mismatch between 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. The effective doping density of the P-type doped microcrystalline silicon oxide decreases with the increase of the oxygen content, resulting in a decrease in the conductivity. The low effective doping rate of the microcrystalline silicon oxide makes the effective tunneling of holes at the interface less, increasing the back surface contact. In summary, for the hole carrier transport on the back surface, the hole tunneling through the interface potential barrier of the microcrystalline silicon oxide and the transparent conductive film layer is increased, affecting the improvement of the cell efficiency. In view of this, a composite P-type doped layer is designed for the solar cell, which can improve the hole carrier transport and thus improve the conversion efficiency of the cell.

[0041] In a first aspect, the present application provides a solar cell. According to an embodiment of the present application, referring to Figure 1 , the solar cell 100 comprises: a silicon substrate 10, the silicon substrate 10 having a first surface and a second surface arranged oppositely; a first intrinsic layer 21, an N-type doped layer 31 and a first transparent conductive film layer 41 arranged in sequence on the first surface of the silicon substrate 10; a second intrinsic layer 22, a P-type doped layer 32 and a second transparent conductive film layer 42 arranged in sequence on the second surface of the silicon substrate 10; the P-type doped layer 32 comprises a first P-type doped layer 321, a second P-type doped layer 322 and a third P-type doped layer 323 arranged in sequence; the first P-type doped layer 321 is in contact with the second intrinsic layer 22; the oxygen doping concentration of the third P-type doped layer 323 < the oxygen doping concentration of the second P-type doped layer 322 ≤ the oxygen doping concentration of the first P-type doped layer 321; the boron doping concentration of the third P-type doped layer 323 ≥ the boron doping concentration of the second P-type doped layer 322 > the boron doping concentration of the first P-type doped layer 321. The boron doping concentration of the first P-type doped layer is 0~1×10 5 cm -3 .

[0042] The present application designs the first P-type doped layer, the second P-type doped layer and the third P-type doped layer in the solar cell, and the size relationship of the oxygen doping concentration and the boron doping concentration of the three layers of P-type doped layers is set at the same time, wherein the first P-type doped layer has a higher oxygen doping concentration and a lower boron doping concentration, the lower boron doping concentration can prevent the boron in the subsequent second P-type doped layer or third P-type doped layer from entering the second intrinsic layer, affecting the passivation effect of the second intrinsic layer; compared with the first P-type doped layer, the oxygen doping concentration of the second P-type doped layer is reduced, which can improve the light transmittance of the cell, and also can improve the hole transport, compared with the first P-type doped layer, the boron doping concentration of the second P-type doped layer is increased, which can establish a hole conductive network, and then improve the conversion efficiency of the cell; the third P-type doped layer has the highest boron doping concentration, which can improve the contact with the second transparent conductive film layer and increase the probability of hole tunneling on the back surface. Thus, the solar cell of the present application can enhance the transport of carriers, reduce the hole contact barrier, and significantly improve the conversion efficiency of the cell.

[0043] In some embodiments, 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. As an example, 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 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 cell can be further improved.

[0044] In some embodiments, 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). As an example, 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 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 cell can be further improved.

[0045] In some embodiments, the oxygen doping concentration of the first P-type doped layer is 1×10 20 cm -3 ~1×10 22 cm -3As an example, the oxygen doping concentration of the first p-type doped layer can be 1 × 10⁻⁶. 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 This can further promote microcrystal nucleation and reduce the carrier transport barrier.

[0046] In some embodiments, as an example, the boron doping concentration of the first p-type doped layer is 0 or 10 cm⁻¹. -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 -37×10 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 Therefore, the amount of boron entering the second intrinsic layer from the second and third P-type doped layers can be further reduced, thus reducing its passivation effect.

[0047] In some embodiments, the oxygen doping concentration of the second P-type doped layer is 1 × 10⁻⁶. 19 cm -3 ~1×10 20 cm -3 As an example, the oxygen doping concentration of the second P-type doped layer is 1 × 10⁻⁶. 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 Therefore, in the second P-type doped layer, moderate oxygen doping provides a wide bandgap, improves the light transmittance of microcrystalline silicon, and thus enhances the conversion efficiency of the battery.

[0048] In some embodiments, the boron doping concentration of the second P-type doped layer is 1 × 10⁻⁶. 19 cm -3 ~1×10 20 cm -3 As an example, the boron doping concentration of the second P-type doped layer is 1 × 10⁻⁶. 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 Therefore, in the second P-type doped layer, appropriate boron doping can establish a hole-conducting network, thereby improving the conversion efficiency of the battery.

[0049] In some embodiments, the oxygen doping concentration of the third P-type doped layer is 0~1×10⁻⁶. 12 cm -3 As an example, the oxygen doping concentration of the third p-type doped layer can be 0 or 10 cm⁻¹. -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 of the third P-type doped layer is 0, the passivation effect of the third P-type doped layer can be improved. When a certain concentration of oxygen is doped in the third P-type doped layer, it can form Si-O bonds with silicon (Si) in amorphous silicon, reduce the interface state density, and suppress carrier recombination.

[0050] In some embodiments, the boron doping concentration of the third P-type doped layer is 1 × 10⁻⁶. 20 cm -3 ~1×10 21 cm -3 As an example, the boron doping concentration of the third P-type doped layer can be 1 × 10⁻⁶. 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 doped layer narrows the space charge region, enhances the electric field strength and tunneling probability, improves contact, and increases the conversion efficiency of the battery.

[0051] In some embodiments, the thickness ratio of the first, second, and third P-type doped layers is 1:(10~25):(1~5). As examples, the thickness ratio 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, or 1:25:5. Therefore, controlling the thickness ratio of the first, second, and third P-type doped layers can improve hole carrier transport and contact characteristics, thereby increasing the battery's conversion efficiency.

[0052] In some embodiments, the thickness of the first P-type doped layer is 1 nm to 2 nm. For 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, or 2 nm. A first P-type doped layer of the above thickness can reduce the number of charge carriers, lower the interfacial barrier with adjacent layers (such as intrinsic amorphous silicon or intrinsic amorphous silicon oxide layers), promote carrier tunneling, reduce contact resistance, and improve the conversion efficiency of the battery.

[0053] In some embodiments, the thickness of the second P-type doped layer is 20 nm to 25 nm. For example, the thickness of the second P-type doped layer is 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, or 25 nm. Therefore, the aforementioned thickness of the second P-type doped layer can guarantee carrier transport paths, provide more carrier transport channels, and thus improve the conversion efficiency of the battery.

[0054] In some embodiments, the thickness of the third P-type doped layer is 3 nm to 5 nm. For example, the thicknesses of the third P-type doped layer are 3 nm, 3.5 nm, 4 nm, 4.5 nm, and 5 nm. Since the third P-type doped layer has the highest boron doping concentration, controlling its thickness within the above range can reduce the number of charge carriers, lower the interfacial barrier with adjacent layers (such as transparent oxide films), promote carrier tunneling, reduce contact resistance, and improve the conversion efficiency of the battery.

[0055] In some embodiments, the first P-type doped layer, the second P-type doped layer, and the third P-type doped layer each independently comprise a P-type amorphous silicon layer, a P-type microcrystalline silicon layer, or a composite layer of both. The higher oxygen doping concentration in the first P-type doped layer can provide nucleation sites for subsequent microcrystalline silicon growth, which is beneficial for microcrystalline nucleation and reduces the carrier transport barrier.

[0056] In some embodiments, the individual film layers are gradually formed, and during the deposition of each film layer, the film material wraps around the side of the silicon substrate to form a structure such as... Figure 2 The shape or appearance. For example... Figure 2 As shown, 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. Therefore, the first P-type doped layer not only enhances the passivation effect of the second intrinsic layer on the side, but also isolates the N-type doped layer and the second P-type doped layer, improving the insulation of the side film, further reducing the risk of battery leakage, and improving the battery's conversion efficiency.

[0057] In some embodiments, such as Figure 2As shown, the second intrinsic layer 22 is disposed on the second surface and side surface of the silicon substrate 10; the 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; the N-type doped layer 31 is disposed on the side surface of the first intrinsic layer 21 and on the surface of the first intrinsic layer 21 away from the silicon substrate 10; the first P-type doped layer 321 is disposed on the side surface of the N-type doped layer 31 and on the surface of the second intrinsic layer 22 away from the silicon substrate 10; the second P-type doped layer 322 is disposed on the side surface of the first P-type doped layer 321 and on the surface of the first P-type doped layer 321 away from the second intrinsic layer 22; and the third P-type doped layer 323 is disposed on the side surface of the second P-type doped layer 322 and on the surface of the second P-type doped layer 322 away from the first P-type doped layer 321.

[0058] 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 both.

[0059] In some embodiments, the thickness of the N-type doped layer is 1 nm to 50 nm. As examples, 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, or 50 nm.

[0060] In some embodiments, the first intrinsic layer may be an intrinsic amorphous silicon layer or an intrinsic amorphous silicon oxide layer.

[0061] In some embodiments, the thickness of the first intrinsic layer is 1 nm to 20 nm. As examples, the thickness of the first intrinsic layer is 1 nm, 5 nm, 10 nm, 15 nm, or 20 nm.

[0062] In some embodiments, the second intrinsic layer may be an intrinsic amorphous silicon layer or an intrinsic amorphous silicon oxide layer.

[0063] In some embodiments, the thickness of the second intrinsic layer is 1 nm to 20 nm. As examples, the thickness of the second intrinsic layer is 1 nm, 5 nm, 10 nm, 15 nm, or 20 nm.

[0064] It is understandable that the materials and deposition thicknesses of the first and second intrinsic layers can be the same or different. The specific materials and deposition thicknesses can be adaptively adjusted according to actual process requirements.

[0065] In some embodiments, the material of the first transparent conductive film layer includes one or more of indium tin oxide (ITO), lanthanide-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), and indium tungsten oxide (IWO).

[0066] 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, or 150 nm.

[0067] In some embodiments, the material of the second transparent conductive film layer includes one or more of indium tin oxide (ITO), lanthanide-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), and indium tungsten oxide (IWO).

[0068] It is understandable 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.

[0069] In some embodiments, the thickness of the second transparent conductive film layer is 50 nm to 150 nm. As examples, 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, or 150 nm.

[0070] In some embodiments, the solar cell further includes a first metal electrode disposed on the side of the first transparent conductive film layer away from the N-type doped layer.

[0071] In some embodiments, the first metal electrode includes one or more of Al, Ti, Ni, Co, Ag, Cu, and Sn.

[0072] In some embodiments, the solar cell further includes a second metal electrode disposed on the side of the second transparent conductive film layer away from the P-type doped layer.

[0073] In some embodiments, the second metal electrode includes one or more of Al, Ti, Ni, Co, Ag, Cu, and Sn.

[0074] In some embodiments, the thickness of the silicon substrate is 50 μm to 200 μm. For 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, or 200 μm.

[0075] In some embodiments, the first surface is the primary light-receiving surface, and the second surface is the secondary light-receiving surface.

[0076] In some embodiments, the silicon substrate is of N-type conductivity, and a PN junction is formed on the secondary light-receiving surface.

[0077] A second aspect of this application provides a method for preparing the above-mentioned solar cell, comprising the following steps: S100. A first intrinsic layer, an N-type doped layer, and a first transparent conductive film layer are sequentially prepared on the first surface of the silicon substrate.

[0078] This application does not impose any particular restrictions on the specific type or 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 single crystal silicon wafer, and the thickness can be 50μm~200μm (specifically, such as 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, 200μm, etc.).

[0079] It is understood that the silicon substrate of this application can be a double-sided polished and clean silicon substrate obtained after double-sided cleaning and polishing, removal of surface organic matter, metal impurities and surface damage layers.

[0080] This application does not specifically limit the process for cleaning the silicon substrate, and it can be any cleaning process, such as standard cleaning 1 or standard cleaning 2; wherein, standard cleaning 1 may include a mixture of ammonium hydroxide, hydrogen peroxide and water, and standard cleaning 2 may include a mixture of hydrochloric acid, hydrogen peroxide and water.

[0081] In some embodiments, a double-sided polished and clean silicon substrate can be texturized. Specifically, texturing refers to forming a microscopic textured structure on the surface of the silicon substrate through chemical etching or physical methods. This structure can increase the residence time of light on the silicon surface, reduce light reflection, and thus improve light absorption efficiency.

[0082] In some embodiments, texturing can be performed using an alkaline solution (such as sodium hydroxide or potassium hydroxide) for chemical etching. The anisotropic etching properties of silicon in an alkaline solution are utilized to form a pyramidal texturing structure.

[0083] In some embodiments, the first intrinsic layer may be prepared using plasma-enhanced chemical vapor deposition (PECVD), hot-wire chemical vapor deposition (HWCVD), or low-pressure chemical vapor deposition (LPCVD).

[0084] In some embodiments, N-type doped layers can be prepared using plasma-enhanced chemical vapor deposition, hot-filament chemical vapor deposition, or low-pressure chemical vapor deposition.

[0085] In some embodiments, the method for fabricating a solar cell further includes: fabricating a first metal electrode on the side of the first transparent conductive film layer away from the N-type doped layer.

[0086] In some embodiments, the first transparent conductive film layer may be prepared by atmospheric pressure chemical vapor deposition (APCVD), radio frequency magnetron sputtering (PVD), or reactive plasma deposition (RPD).

[0087] In some embodiments, the first metal electrode may 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 may be prepared by electroplating one or more of Al, Ti, Ni, Co, Ag, Cu, and Sn.

[0088] S200: A second intrinsic layer, a P-type doped layer, and a second transparent conductive film layer are sequentially prepared on the second surface of the silicon substrate; The preparation of 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; The preparation of the second P-type doped layer includes: performing a second doping treatment on the surface of the first P-type doped layer that is 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 that is away from the first P-type doped layer to obtain the third P-type doped layer.

[0089] In some embodiments, H2, silane, and an oxygen source are introduced during the first doping process.

[0090] In some embodiments, during the first doping process, the flow rate ratio of H2, silane, and 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 controlled to obtain a solar cell with high conversion efficiency.

[0091] 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.

[0092] In some embodiments, the first doping treatment includes: introducing hydrogen gas at a flow rate of 20,000–30,000 sccm, silane gas at a flow rate of 50–80 sccm, and CO2 and / or N2O gas at a flow rate of 100–200 sccm at 140–160 °C and 4–6 Torr; the duration of the first doping treatment is 10–20 s. This further improves hole carrier transport and increases the conversion efficiency of the battery.

[0093] As an example, the temperature of the first doping treatment can be 140, 145, 150, 155, or 160°C, the pressure can be 4, 4.5, 5, 5.5, or 6 Torr, the hydrogen flow rate can be 20,000, 21,000, 22,000, 23,000, 24,000, 25,000, 26,000, 27,000, 28,000, 29,000, or 30,000 sccm, the silane flow rate can be 50, 55, 60, 65, 70, 75, or 80 sccm, and the CO2 and / or N2O flow rate can be 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, or 200 sccm.

[0094] In some embodiments, the first P-type doped layer may be prepared using plasma-enhanced chemical vapor deposition, hot-filament chemical vapor deposition, or low-pressure chemical vapor deposition.

[0095] In some embodiments, the power used to prepare the first P-type doped layer is 4000~5000W. As an example, the power used to deposit the first P-type doped layer can be 4000, 4100, 4200, 4300, 4400, 4500, 4600, 4700, 4800, 4900, or 5000W.

[0096] In some embodiments, H2, silane, an oxygen source, and a boron source are introduced during the second doping process.

[0097] In some embodiments, during the second doping process, the flow rate ratio of H2, silane, oxygen source, and 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 doped layer, as well as the thickness of the second P-type doped layer, can be effectively controlled to obtain a solar cell with high conversion efficiency.

[0098] In some embodiments, the boron source includes BH3, B3H6, and B4H. 10 One or more of the following; the specific components of the silane and oxygen source in the second doping treatment are as described above and will not be repeated here.

[0099] In some embodiments, the second doping treatment includes: introducing hydrogen gas 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 at 140–160 °C and 4–6 Torr; the duration of the second doping treatment is 100–200 s. This further improves hole carrier transport and increases the conversion efficiency of the battery.

[0100] As an example, the temperature of the second doping treatment can be 140, 145, 150, 155, or 160°C, the pressure can be 4, 4.5, 5, 5.5, or 6 Torr, the hydrogen flow rate can be 20,000, 21,000, 22,000, 23,000, 24,000, or 25,000 sccm, the silane flow rate can be 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 sccm, the CO2 and / or N2O flow rate can be 10, 15, 20, 25, or 30 sccm, and the borane flow rate can be 20, 25, 30, 35, 40, 45, or 50 sccm.

[0101] In some embodiments, the second P-type doped layer can be prepared using plasma-enhanced chemical vapor deposition, hot-filament chemical vapor deposition, or low-pressure chemical vapor deposition.

[0102] In some embodiments, the power for depositing the second P-type doped layer is 5000~7000W. As examples, the power for depositing the second P-type doped layer is 5000, 5100, 5200, 5300, 5400, 5500, 5600, 5700, 5800, 5900, 6000, 6100, 6200, 6300, 6400, 6500, 6600, 6700, 6800, 6900, or 7000W.

[0103] In some embodiments, one or more of H2, silane, oxygen source, and boron source are introduced during the third doping process.

[0104] In some embodiments, H2, silane, and a boron source are introduced during the third doping process.

[0105] In other embodiments, H2, silane, an oxygen source, and a boron source are introduced during the third doping process.

[0106] In some embodiments, the amount of oxygen source introduced in the third doping treatment is less than the amount of oxygen source introduced in the second doping treatment and less than the amount of oxygen source introduced in the first doping treatment; the amount of boron source introduced in the third doping treatment is greater than or equal to the amount of boron source introduced in the second doping treatment and greater than the amount of boron source introduced in the first doping treatment. This further improves hole carrier transport and increases the conversion efficiency of the battery.

[0107] In some embodiments, the flow rate ratio of H2, silane, and boron source in the third doping treatment is (200~500):1:(0.2~4). By optimizing the conditions of the third doping, the oxygen doping concentration and boron doping concentration of the third P-type doped layer, as well as the thickness of the third P-type doped layer, can be effectively controlled to obtain a solar cell with high conversion efficiency. 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 doped layer prepared under oxygen-free conditions has fewer defect states and a higher electron tunneling probability, and can directly contact the second transparent conductive film layer, avoiding the potential barrier caused by oxygen and reducing the contact resistance.

[0108] The specific components of the silane, oxygen source, and boron source in the third doping treatment are as described above and will not be repeated here.

[0109] In some embodiments, the third doping treatment includes: introducing hydrogen gas 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 0–30 sccm, and borane at a flow rate of 20–200 sccm at 140–160 °C and 4–6 Torr; the duration of the third doping treatment is 30–60 s. This further improves hole carrier transport and increases the conversion efficiency of the battery.

[0110] As an example, the temperature of the third doping treatment can be 140, 145, 150, 155, or 160°C, the pressure can be 4, 4.5, 5, 5.5, or 6 Torr, the hydrogen flow rate can be 20,000, 21,000, 22,000, 23,000, 24,000, or 25,000 sccm, the silane flow rate can be 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 sccm, and the borane flow rate can be 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, or 200 sccm.

[0111] In some embodiments, the third P-type doped layer can be prepared using plasma-enhanced chemical vapor deposition, hot-filament chemical vapor deposition, or low-pressure chemical vapor deposition.

[0112] In some embodiments, the power for depositing the third P-type doped layer is 5000~7000W. As examples, the power for depositing the third P-type doped layer is 5000, 5100, 5200, 5300, 5400, 5500, 5600, 5700, 5800, 5900, 6000, 6100, 6200, 6300, 6400, 6500, 6600, 6700, 6800, 6900, or 7000W.

[0113] In some embodiments, the second intrinsic layer may be prepared using plasma-enhanced chemical vapor deposition, hot-wire chemical vapor deposition, or low-pressure chemical vapor deposition.

[0114] In some embodiments, the method for fabricating a solar cell includes the following steps: The second intrinsic layer is prepared on the second surface of the silicon substrate, and the first intrinsic layer is prepared on the first surface of the silicon substrate. The N-type doped layer is prepared on the side of the first intrinsic layer away from the silicon substrate, and the P-type doped layer is prepared on the side of the second intrinsic layer away from the silicon substrate.

[0115] In some embodiments, the method for fabricating a solar cell specifically includes the following steps: The second intrinsic layer is prepared on the second surface and 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 doped layer is prepared on the side surface of the first intrinsic layer and on the surface away from the silicon substrate; The first P-type doped layer is prepared on the side of the N-type doped layer and on 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 far 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.

[0116] During the deposition of each film layer, the film material also wraps around the sides of the silicon substrate. Depending on the process, different film layer stacking relationships are formed on the sides. Specifically, when using an N-type silicon substrate, the first surface of the silicon substrate is the front side (the main light-receiving surface), and the second surface of the silicon substrate is the back side (the secondary light-receiving surface). In this structure, the PN junction is formed on the back side of the battery, and the high-low junction (N-N+) is formed on the front side of the battery. This application has designed a specific process sequence: first, a protective layer is formed on the back side, then the key film layer on the front side is formed, and finally the PN junction on the back side is formed, which can further improve the edge leakage phenomenon.

[0117] In some embodiments, the method for fabricating a solar cell further includes: fabricating a second metal electrode on the side of the second transparent conductive film layer away from the P-type doped layer.

[0118] 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.

[0119] 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.

[0120] In a third aspect, this application provides a photovoltaic module, including the aforementioned solar cell, and / or a solar cell prepared by the method described above. Therefore, this photovoltaic module exhibits good electrochemical performance and high conversion efficiency.

[0121] To facilitate the explanation of the technical solution of this application, some concepts involved in the embodiments of this application will be described.

[0122] N-type: also known as electronic type. In N-type semiconductors, free electrons are the majority carriers, and holes are the minority carriers.

[0123] P-type: also known as hole-type. In a P-type semiconductor, holes are the majority carriers and free electrons are the minority carriers.

[0124] The embodiments of this application are described in detail below.

[0125] The borane used in the embodiments of this application is B2H6, and the silane is SiH4.

[0126] Example 1 The solar cell of this embodiment is prepared by the following steps: (1) Cleaning and velveting N-type monocrystalline silicon wafers with a thickness of 150μm are selected. The front and back sides of the silicon wafers are cleaned using a tank cleaning and texturing machine. Then, the silicon wafers are texturized with sodium hydroxide solution to form a textured surface on the front and back sides of the silicon wafers.

[0127] (2) Preparation of intrinsic layer The intrinsic layer was prepared by plasma-enhanced chemical vapor deposition (PECVD). A back intrinsic layer was deposited on the back side of the silicon wafer obtained in step (1), with the following specific parameters: hydrogen and silane were introduced. The intrinsic layer was prepared at 0.5 Torr, with a thickness controlled between 5 and 7 nm; the deposition power was 200 W, the hydrogen flow rate was 1500 sccm, and the silane flow rate was 750 sccm. A 6 nm thick front intrinsic layer was deposited on the front side of the silicon wafer obtained in step (1), and the preparation parameters of the front intrinsic layer were the same as those of the back intrinsic layer.

[0128] (3) Preparation of N-type doped layer A 25 nm thick N-type doped layer is deposited on the front side of the silicon wafer obtained in step (2) using plasma-enhanced chemical vapor deposition (PECVD).

[0129] (4) Preparation of P-type doped layer The back side of the silicon wafer obtained in step (3) is sequentially deposited with a first P-type doped layer, a second P-type doped layer, and a third P-type doped layer using plasma-enhanced chemical vapor deposition (PECVD). The specific parameters are as follows: The first p-type doped layer was prepared by introducing hydrogen, silane, and CO2 at a pressure of 5 Torr and a deposition power of 4500 W. The hydrogen flow rate was 25000 sccm, the silane flow rate was 70 sccm, and the CO2 flow rate was 150 sccm. The deposition temperature was 150℃, the deposition time was 20 s, the thickness of the first p-type doped layer was 1 nm, and the oxygen doping concentration was 1 × 10⁻⁶. 21 cm -3 The boron doping concentration is 0.

[0130] A second P-type doped layer was prepared by introducing hydrogen, silane, CO2, and borane at a pressure of 5 Torr and a deposition power of 6000 W. The hydrogen flow rate was 22000 sccm, the silane flow rate was 75 sccm, the CO2 flow rate was 20 sccm, and the borane flow rate was 25 sccm. The deposition temperature was controlled at 150℃, the deposition time was 180 s, the thickness of the second P-type doped layer was controlled at 20 nm, and the oxygen doping concentration was 1×10⁻⁶. 19 cm -3 The boron doping concentration is 1×10 19 cm -3 .

[0131] The third P-type doped layer was prepared by introducing hydrogen, silane, and borane at a pressure of 5 Torr and a deposition power of 6000 W. The hydrogen flow rate was 22000 sccm, the silane flow rate was 75 sccm, and the borane flow rate was 150 sccm. The deposition temperature was controlled at 150℃, the deposition time was 40 s, the thickness of the third P-type doped layer was controlled at 3 nm, the oxygen doping concentration was 0, and the boron doping concentration was 1×10⁻⁶. 20 cm -3 .

[0132] (5) Deposition of indium tin oxide layer By magnetron sputtering, 100 nm thick indium tin oxide (ITO) layers are deposited on the front and back sides of the silicon wafer obtained in step (4).

[0133] (6) Preparation of metal electrodes Silver metal electrodes are fabricated on the indium tin oxide (ITO) layers on the front and back sides of a silicon wafer, respectively.

[0134] Example 2 The solar cell fabrication method in this embodiment differs from that in Embodiment 1 only in that the preparation parameters of the first P-type doped layer in step (4) are adjusted: the hydrogen flow rate is 27500 sccm, and the silane flow rate is 50 sccm. The oxygen doping concentration of the first P-type doped layer in this embodiment is 1 × 10⁻⁶. 21 cm -3 The boron doping concentration is 0.

[0135] The remaining steps are performed in accordance with the method in Example 1.

[0136] Example 3 The solar cell fabrication method in this embodiment differs from that in Embodiment 1 only in that the preparation parameters of the third P-type doped layer in step (4) are adjusted: borane flow rate range 180 sccm, CO2 flow rate range 20 sccm. The oxygen doping concentration of the third P-type doped layer in this embodiment is 1 × 10⁻⁶. 10 cm -3 The boron doping concentration is 1×10 21 cm -3 .

[0137] Example 4 The solar cell fabrication method in this embodiment differs from that in Embodiment 1 only in that the preparation parameters of the third P-type doped layer in step (4) are adjusted: borane flow rate range 200 sccm, CO2 flow rate range 20 sccm. The oxygen doping concentration of the third P-type doped layer in this embodiment is 1 × 10⁻⁶. 10 cm -3 The boron doping concentration is 1×10 22 cm -3 .

[0138] Comparative Example 1 The method for preparing the solar cell in this comparative example differs from that in Example 1 in that step (4) is adjusted as follows: A doped microcrystalline silicon oxide layer was prepared by introducing hydrogen, silane, CO2, and borane into the back side. The pressure was 5 Torr, the deposition power was 6000 W, the hydrogen flow rate was 25000 sccm, the silane flow rate was 75 sccm, the CO2 flow rate was 20 sccm, the borane flow rate was 60 sccm, the deposition temperature was controlled at 150℃, and the thickness of the doped microcrystalline silicon oxide layer was 32 nm.

[0139] The remaining steps are performed in accordance with the method in Example 1.

[0140] Test case The solar cells obtained in the examples and comparative examples were tested.

[0141] Backside hole tunneling contact resistivity: tested using a TLM tester.

[0142] Short-circuit current (Isc): Tested using a silicon solar cell Sinton IV tester.

[0143] Fill factor (FF): Tested using a silicon solar cell Sinton IV tester.

[0144] Conversion efficiency (Eff): Tested using a silicon solar cell Sinton IV tester.

[0145] The experimental results are shown in Table 1.

[0146] Table 1

[0147] As shown in Table 1, compared with Comparative Example 1 which prepared a conventional single-layer P-type doped layer, Examples 1-4 of this application designed a three-layer P-type doped layer. The electrical performance results show that the short-circuit current of the battery in Comparative Example 1 is comparable to that of the examples in this application. The batteries in Examples 1-4 of this application have lower back hole tunneling contact resistivity, higher conversion efficiency, and higher fill factor.

[0148] Comparing Example 1 and Example 2, it can be seen that Example 2, by increasing the hydrogen flow rate while reducing the silane flow rate, ultimately achieved a significant improvement in the fill factor and an increase in conversion efficiency of 0.04%.

[0149] Comparing Examples 1 and 3 and 4, it can be seen that in the case of oxygen doping, it is necessary to increase the boron doping concentration, which can effectively improve the battery efficiency. This may be because oxygen doping increases the defect state density of the thin film, requiring high boron doping to improve hole contact.

[0150] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0151] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled 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, include: Silicon substrate; The silicon substrate has a first surface and a second surface disposed opposite to each other; A first intrinsic layer, an N-type doped layer, and a first transparent conductive film layer are sequentially disposed 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 disposed 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 arranged sequentially. The first P-type doped layer and the second intrinsic layer are in contact; The oxygen doping concentration of the third P-type doped layer is less than the oxygen doping concentration of the second P-type doped layer and less than the oxygen doping concentration of the first P-type doped layer. The boron doping concentration of the third P-type doped layer is greater than or equal to the boron doping concentration of the second P-type doped layer and greater than the boron doping concentration of the first P-type doped layer.

2. The solar cell according to claim 1, characterized in that, At least one of the first P-type doped layer, the second P-type doped layer, and the third P-type doped layer comprises a P-type amorphous silicon layer, a P-type microcrystalline silicon layer, or a composite layer of the two.

3. The solar cell according to claim 1, characterized in that, The ratio of oxygen doping concentration of the first P-type doped layer to 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).

4. The solar cell according to claim 1 or 3, characterized in that, The oxygen doping concentration of the first P-type doped layer is 1×10⁻⁶. 20 cm -3 ~1×10 22 cm -3 ; And / or, the boron doping concentration of the first P-type doped layer is 0~1×10⁻⁶. 5 cm -3 ; And / or, the oxygen doping concentration of the second P-type doped layer is 1 × 10⁻⁶. 19 cm -3 ~1×10 20 cm -3 ; And / or, the boron doping concentration of the second P-type doped layer is 1×10⁻⁶. 19 cm -3 ~1×10 20 cm -3 ; And / or, the oxygen doping concentration of the third P-type doped layer is 0~1×10⁻⁶. 12 cm -3 ; And / or, the boron doping concentration of the third P-type doped layer is 1×10⁻⁶. 20 cm -3 ~1×10 21 cm -3 .

5. 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).

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

7. The solar cell according to claim 1, characterized in that, The first P-type doped layer overlaps with the N-type doped layer on the side of the silicon substrate, and the first P-type doped layer is disposed on the outside of the N-type doped layer.

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

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

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

11. The solar cell according to claim 1, characterized in that, 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.

12. A method for preparing a solar cell, used to form a solar cell according to any one of claims 1 to 11, characterized in that, Includes the following steps: A first intrinsic layer, an N-type doped layer, and a first transparent conductive film layer are sequentially prepared on the first surface of a silicon substrate. A second intrinsic layer, a P-type doped layer, and a second transparent conductive film layer are sequentially prepared on the second surface of a silicon substrate; The step of 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; The step of preparing the second P-type doped layer includes: performing a second doping treatment on the surface of the first P-type doped layer that is far from the second intrinsic layer to obtain the second P-type doped layer; The steps for preparing the third P-type doped layer include: performing a third doping treatment on the surface of the second P-type doped layer that is away from the first P-type doped layer to obtain the third P-type doped layer.

13. The method for preparing a solar cell according to claim 12, characterized in that, In the first doping process, H2, silane, and an oxygen source are introduced; And / or, H2, silane, oxygen source and boron source are introduced during the second doping treatment; And / or, one or more of H2, silane, oxygen source and boron source are introduced during the third doping process.

14. The method for preparing a solar cell according to claim 13, characterized in that, The amount of oxygen source introduced in the third doping process is less than the amount of oxygen source introduced in the second doping process and less than the amount of oxygen source introduced in the first doping process. And / or, the amount of boron source introduced in the third doping process is ≥ the amount of boron source introduced in the second doping process > the amount of boron source introduced in the first doping process.

15. The method for preparing a solar cell according to claim 13 or 14, characterized in that, In the first doping process, the flow rate ratio of H2, silane and oxygen source is (250~600):1:(1~4). And / or, in the second doping treatment, the flow rate ratio of H2, silane, oxygen source and boron source is (200~500):1:(0.1~1):(0.2~1); And / or, in the third doping treatment, the flow rate ratio of H2, silane and boron source is (200~500):1:(0.2~4).

16. The method for preparing a solar cell according to claim 12, characterized in that, Includes the following steps: The second intrinsic layer is prepared on the second surface and 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 doped layer is prepared on the side surface of the first intrinsic layer and on the surface away from the silicon substrate; The first P-type doped layer is prepared on the side of the N-type doped layer and on 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 far 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.

17. A photovoltaic module, characterized in that, Includes solar cells according to any one of claims 1 to 11, and / or solar cells prepared by the method of preparing solar cells according to any one of claims 12 to 16.

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