Method for manufacturing a solar cell and photovoltaic module

Abstract

The application discloses a preparation method of a solar cell and a photovoltaic module. The preparation method of the solar cell comprises the following steps: providing a silicon substrate, wherein the silicon substrate comprises a first surface and a second surface which are oppositely arranged along a first direction; sequentially forming a first silicon oxide layer, a first polysilicon layer, a second silicon oxide layer and a second polysilicon layer on the second surface; performing phosphorus diffusion to convert the first polysilicon layer into a first doped crystalline silicon layer and the second polysilicon layer into a second doped crystalline silicon layer; and sequentially removing the second doped crystalline silicon layer and the second silicon oxide layer. The preparation method of the solar cell can thin the first doped crystalline silicon layer under the premise of ensuring the uniformity and passivation effect of the first doped crystalline silicon layer, thereby improving the characteristics of the solar cell.

Description

Technical Field

[0001] This invention relates to the field of solar cells, and more specifically, to a method for preparing a solar cell and a photovoltaic module. Background Technology

[0002] To improve the photoelectric conversion performance of solar cells, a doped polycrystalline silicon layer is usually fabricated on one side of the silicon substrate of the solar cell. The doped polycrystalline silicon layer forms band bending on one side of the silicon substrate, enabling selective transport of charge carriers and reducing recombination losses. However, the presence of the doped polycrystalline silicon layer will cause optical absorption, so it is necessary to thin the doped polycrystalline silicon layer to reduce optical absorption.

[0003] In existing technologies, there are bottlenecks in thinning doped polysilicon layers. If a polysilicon layer is formed by deposition equipment and then phosphorus diffusion is performed to convert the polysilicon layer into a doped polysilicon layer, the uniformity of the polysilicon deposition equipment is limited, and the process window during phosphorus diffusion is limited. It is difficult to obtain a uniform doped polysilicon layer without damaging the silicon oxide layer between the silicon substrate and the doped polysilicon layer. If a polysilicon layer is formed by deposition equipment and then phosphorus diffusion is performed to convert the polysilicon layer into a doped polysilicon layer, and finally the doped polysilicon layer is thinned by chemical etching, it is difficult to precisely control the degree of chemical etching, and it may even damage the silicon oxide layer between the silicon substrate and the doped polysilicon layer, resulting in a decrease in passivation effect. Summary of the Invention

[0004] In view of this, the present invention provides a method for preparing a solar cell and a photovoltaic module.

[0005] On one hand, the present invention provides a method for preparing a solar cell, comprising:

[0006] A silicon substrate is provided, the silicon substrate including a first surface and a second surface disposed opposite to each other along a first direction;

[0007] A first silicon oxide layer is formed on the second surface;

[0008] A first polycrystalline silicon layer is formed on the side of the first silicon oxide layer away from the silicon substrate;

[0009] A second silicon oxide layer is formed on the side of the first polysilicon layer away from the silicon substrate;

[0010] A second polycrystalline silicon layer is formed on the side of the second silicon oxide layer away from the silicon substrate;

[0011] Phosphorus diffusion is performed to convert the first polycrystalline silicon layer into a first doped crystalline silicon layer and the second polycrystalline silicon layer into a second doped crystalline silicon layer.

[0012] The second doped silicon layer and the second silicon oxide layer are removed sequentially.

[0013] On the other hand, the present invention provides a photovoltaic module, comprising:

[0014] The solar cell is fabricated using the solar cell fabrication method described above.

[0015] The first adhesive film is located on one side of the solar cell;

[0016] The second adhesive film is located on the side of the solar cell away from the first adhesive film;

[0017] The first glass is located on the side of the first adhesive film away from the solar cell;

[0018] The second glass is located on the side of the second encapsulant film away from the solar cell.

[0019] Compared with the prior art, the method for preparing solar cells provided by the present invention achieves at least the following beneficial effects:

[0020] The method for fabricating a solar cell provided by the present invention includes: providing a silicon substrate, the silicon substrate including a first surface and a second surface disposed opposite to each other along a first direction; forming a first silicon oxide layer on the second surface; forming a first polycrystalline silicon layer on the side of the first silicon oxide layer away from the silicon substrate; forming a second silicon oxide layer on the side of the first polycrystalline silicon layer away from the silicon substrate; forming a second polycrystalline silicon layer on the side of the second silicon oxide layer away from the silicon substrate; performing phosphorus diffusion to convert the first polycrystalline silicon layer into a first doped crystalline silicon layer and the second polycrystalline silicon layer into a second doped crystalline silicon layer; and sequentially removing the second doped crystalline silicon layer and the second silicon oxide layer. By depositing a first polycrystalline silicon layer, a second silicon oxide layer, and a second polycrystalline silicon layer stacked on the back of a solar cell, the influence of deposition equipment uniformity can be reduced, phosphorus diffusion can be better matched, and it helps to form a uniform doped polycrystalline silicon layer. The presence of the second silicon oxide can improve the process window and further control the phosphorus diffusion process. When removing the second doped silicon layer, the second silicon oxide layer can also be used as a self-stopping layer for the reaction, avoiding damage to the first doped silicon layer and ensuring that the first doped silicon layer has a good passivation effect. Therefore, the solar cell fabrication method provided by this invention can reduce the thickness of the first doped silicon layer while ensuring the uniformity and passivation effect of the first doped silicon layer, thereby improving the characteristics of the solar cell.

[0021] Of course, any product implementing this invention does not necessarily need to achieve all of the technical effects described above at the same time.

[0022] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0023] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0024] Figure 1 This is a schematic diagram of a solar cell structure provided by the present invention;

[0025] Figure 2 This is a schematic diagram of another structure of the solar cell provided by the present invention;

[0026] Figure 3 This is another structural schematic diagram of the solar cell provided by the present invention;

[0027] Figure 4 This is another structural schematic diagram of the solar cell provided by the present invention;

[0028] Figure 5 This is a flowchart of a method for preparing a solar cell provided by the present invention;

[0029] Figure 6 This is another structural schematic diagram of the solar cell provided by the present invention;

[0030] Figure 7 This is a flowchart of the formation of the emitter of a solar cell provided by the present invention;

[0031] Figure 8 This is a structural diagram of a photovoltaic module provided by the present invention. Detailed Implementation

[0032] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0033] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0034] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0035] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0036] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0037] Reference Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 , Figure 1 This is a schematic diagram of a solar cell structure provided by the present invention. Figure 2 This is a schematic diagram of another structure of the solar cell provided by the present invention. Figure 3 This is another structural schematic diagram of the solar cell provided by the present invention. Figure 4 This is another structural schematic diagram of the solar cell provided by the present invention. Figure 5 This is a flowchart illustrating a method for fabricating a solar cell 100 provided by the present invention, specifically a particular embodiment of the method, including:

[0038] S101: A silicon substrate 01 is provided, the silicon substrate 01 including a first surface 02 and a second surface 03 disposed opposite to each other along a first direction X;

[0039] S102: A first silicon oxide layer 04 is formed on the second surface 03;

[0040] S103: A first polysilicon layer 05 is formed on the side of the first silicon oxide layer 04 away from the silicon substrate 01;

[0041] S104: A second silicon oxide layer 06 is formed on the side of the first polysilicon layer 05 away from the silicon substrate 01;

[0042] S105: A second polysilicon layer 07 is formed on the side of the second silicon oxide layer 06 away from the silicon substrate 01;

[0043] S106: Perform phosphorus diffusion to transform the first polycrystalline silicon layer 05 into the first doped crystalline silicon layer 08 and the second polycrystalline silicon layer 07 into the second doped crystalline silicon layer 09.

[0044] S107: Sequentially remove the second doped silicon layer 09 and the second silicon oxide layer 06.

[0045] It is understandable that after step S107, the process includes printing the front electrode paste and the back electrode paste, followed by sintering to form a complete solar cell 100 structure. However, it is not limited to this; see reference [link to relevant documentation]. Figure 1The primary function of the first silicon oxide layer 04 formed in step S102 is to serve as a tunneling layer for majority carriers, while simultaneously passivating the surface of the silicon substrate 01 and reducing interface states. In steps S103, S104, and S105, the thickness of the first polysilicon layer 05, along the direction perpendicular to the silicon substrate 01, is the preset thickness of the first doped polysilicon. By adding the second silicon oxide layer 06 and the second polysilicon layer 07, the deposition thickness of the deposition equipment is increased, reducing the impact on the uniformity of the deposition equipment. The presence of the second silicon oxide layer 06 can slow down the phosphorus diffusion process and help control the degree of phosphorus diffusion. (Refer to...) Figure 2 In step S106, phosphorus diffusion is performed to transform the first polycrystalline silicon layer 05 into a first doped silicon layer 08 and the second polycrystalline silicon layer 07 into a second doped silicon layer 09. In practical applications, the first doped silicon layer 08 is located on the side of the metal electrode closer to the silicon substrate 01. The first doped silicon layer 08 can reduce the recombination current on the surface of the silicon substrate 01 to a very low level. Furthermore, the portion of the first doped silicon layer 08 located in the area covered by the metal electrode can significantly reduce the metal recombination current density between the metal electrode and the silicon substrate 01. Because the presence of the first doped silicon layer 08 reduces the total saturated recombination current density of the solar cell 100, it can greatly improve the open-circuit voltage and conversion efficiency of the solar cell 100. (Refer to...) Figure 4 and Figure 5 ,exist Figure 4 The diagram illustrates the process of first removing the second doped silicon layer 09, and then... Figure 5 The diagram illustrates that after removing the second doped silicon layer 09, the second silicon oxide layer 06 is removed. The second silicon oxide layer 06 can serve as a reaction self-stopping layer for the second doped silicon layer 09, meaning that the second silicon oxide layer 06 does not react with the chemical solvent used to remove the second doped silicon layer 09, and the chemical solvent used to remove the second silicon oxide layer 06 does not react with the first doped silicon layer 08, which helps to protect the first doped silicon layer 08.

[0046] Compared with the prior art, the method for preparing the solar cell 100 provided by the present invention has at least the following advantages:

[0047] The method for fabricating a solar cell 100 provided by the present invention includes: providing a silicon substrate 01, the silicon substrate 01 including a first surface 02 and a second surface 03 disposed opposite to each other along a first direction X; forming a first silicon oxide layer 04 on the second surface 03; forming a first polycrystalline silicon layer 05 on the side of the first silicon oxide layer 04 away from the silicon substrate 01; forming a second silicon oxide layer 06 on the side of the first polycrystalline silicon layer 05 away from the silicon substrate 01; forming a second polycrystalline silicon layer 07 on the side of the second silicon oxide layer 06 away from the silicon substrate 01; performing phosphorus diffusion to convert the first polycrystalline silicon layer 05 into a first doped crystalline silicon layer 08 and the second polycrystalline silicon layer 07 into a second doped crystalline silicon layer 09; and sequentially removing the second doped crystalline silicon layer 09 and the second silicon oxide layer 06. By depositing a first polycrystalline silicon layer 05, a second silicon oxide layer 06, and a second polycrystalline silicon layer 07 on the back side of the solar cell 100, the influence of deposition equipment uniformity can be reduced, phosphorus diffusion can be better matched, and it helps to form a uniform doped polycrystalline silicon layer. The presence of the second silicon oxide can improve the process window and further control the phosphorus diffusion process. When removing the second doped silicon layer 09, the second silicon oxide layer 06 can also be used as a self-stopping layer for the reaction to avoid damage to the first doped silicon layer 08 and ensure that the first doped silicon layer 08 has a good passivation effect. Therefore, the method for preparing the solar cell 100 provided by the present invention can reduce the thickness of the first doped silicon layer 08 while ensuring the uniformity and passivation effect of the first doped silicon layer 08, thereby improving the characteristics of the solar cell 100.

[0048] In some alternative embodiments, refer to Figure 2 and Figure 6 , Figure 6 This is another structural schematic diagram of the solar cell 100 provided by the present invention. It includes phosphorus diffusion to convert the first polycrystalline silicon layer 05 into a first doped crystalline silicon layer 08 and the second polycrystalline silicon layer 07 into a second doped crystalline silicon layer 09, and further comprises:

[0049] A phosphosilicate glass layer 10 is formed on the side of the second doped silicon layer 09 away from the first doped silicon layer 08;

[0050] Remove the phosphorus silica glass layer 10 before removing the second doped crystalline silicon layer 09.

[0051] It is understandable that during the phosphorus diffusion process, a phosphosilicate glass layer 10 will be formed on the side of the second doped silicon layer 09 away from the second silicon oxide layer 06. The phosphosilicate glass layer 10 is non-conductive. In order to form a good ohmic contact and reduce light reflection, the formed phosphosilicate glass layer 10 needs to be removed.

[0052] In some alternative embodiments, reference continues to be made to... Figure 2 and Figure 6 Removing the phosphosilicate glass layer 10 includes:

[0053] Use a hydrofluoric acid solution with a concentration of 3% to 10% to immerse one side for 30 to 120 seconds.

[0054] It is understood that the hydrofluoric acid solution reacts with the phosphosilicate glass layer 10 and causes it to complex and peel off, thereby achieving the purpose of removing the phosphosilicate glass layer 10. The concentration of the hydrofluoric acid solution and the soaking time of the phosphosilicate glass layer 10 in the hydrofluoric acid solution will affect the removal effect of the phosphosilicate glass layer 10. Soaking the phosphosilicate glass layer 10 in a 3% to 10% hydrofluoric acid solution on one side for 30 to 120 seconds helps to remove the phosphosilicate glass layer 10 more cleanly, that is, the side of the second doped silicon layer 09 away from the second silicon oxide layer 06 achieves a hydrophobic effect. Of course, the concentration of the hydrofluoric acid solution and the soaking time of the phosphosilicate glass layer 10 in the hydrofluoric acid solution can be adjusted according to actual needs. This embodiment does not make specific limitations in this regard.

[0055] In some alternative embodiments, reference continues to be made to... Figure 1 and Figure 5 The process conditions for forming the first silicon oxide layer 04 on the second surface 03 are as follows:

[0056] Under temperature conditions of 570 to 630°C, oxygen was introduced at a flow rate of 30,000 to 40,000 sccm, and the deposition time ranged from 300 to 500 s.

[0057] Specifically, the process conditions for forming the first oxide layer can be adjusted according to actual needs. This embodiment does not impose specific limitations on this. Alternatively, the process conditions can be adjusted as follows: 30,000 sccm of oxygen can be introduced at 570°C for 300 seconds (where 's' represents seconds); 40,000 sccm of oxygen can be introduced at 570°C for 300 seconds; 30,000 sccm of oxygen can be introduced at 570°C for 500 seconds; 40,000 sccm of oxygen can be introduced at 570°C for 500 seconds; 40,000 sccm of oxygen can be introduced at 630°C for 300 seconds; 30,000 sccm of oxygen can be introduced at 630°C for 500 seconds; 40,000 sccm of oxygen can be introduced at 630°C for 500 seconds; 40,000 sccm of oxygen can be introduced at 630°C for 500 seconds.

[0058] In some alternative embodiments, reference continues to be made to... Figure 1 and Figure 5 The process conditions for forming the first polysilicon layer 05 on the side of the first silicon oxide layer 04 away from the silicon substrate 01 are as follows:

[0059] At temperatures ranging from 570 to 630°C, silane with a gas flow rate ranging from 300 to 1500 sccm was introduced, and the deposition time ranged from 2 to 15 minutes.

[0060] Specifically, the deposition process can be carried out at 570°C with 300 sccm of silane for 2 minutes, or at 570°C with 1500 sccm of silane for 2 minutes, or at 570°C with 300 sccm of silane for 15 minutes, or at 570°C with 1500 sccm of silane for 15 minutes, or at 630°C with 300 sccm of silane for 2 minutes, or at 630°C with 1500 sccm of silane for 15 minutes, or at 630°C with 1500 sccm of silane for 15 minutes. Of course, the process conditions for forming the first polycrystalline silicon can be adjusted according to actual needs, and this embodiment does not impose specific limitations on this.

[0061] In some alternative embodiments, reference continues to be made to... Figure 1 and Figure 5 The process conditions for forming the second silicon oxide layer 06 on the side of the first polysilicon layer 05 away from the silicon substrate 01 are as follows:

[0062] Under temperature conditions of 570 to 630°C, oxygen was introduced at a flow rate of 30,000 to 40,000 sccm, and the deposition time ranged from 300 to 500 s.

[0063] Specifically, the process conditions for forming the second silicon oxide layer 06 can be adjusted according to actual needs, and this embodiment does not impose specific limitations on them. These conditions can be achieved by introducing 30,000 sccm of oxygen at 570°C for 300 seconds, or by introducing 40,000 sccm of oxygen at 570°C for 300 seconds, or by introducing 30,000 sccm of oxygen at 570°C for 500 seconds, or by introducing 40,000 sccm of oxygen at 630°C for 300 seconds, or by introducing 30,000 sccm of oxygen at 630°C for 500 seconds, or by introducing 40,000 sccm of oxygen at 630°C for 500 seconds.

[0064] In some alternative embodiments, reference continues to be made to... Figure 1 and Figure 5 The process conditions for forming the second polysilicon layer 07 on the side of the second silicon oxide layer 06 away from the silicon substrate 01 are as follows:

[0065] At temperatures ranging from 570 to 630°C, silane with a gas flow rate ranging from 300 to 1500 sccm was introduced, and the deposition time ranged from 3 to 20 minutes.

[0066] Specifically, the deposition process can be carried out at 570°C with 300 sccm of silane for 3 minutes, or at 570°C with 1500 sccm of silane for 3 minutes, or at 570°C with 300 sccm of silane for 20 minutes, or at 570°C with 1500 sccm of silane for 20 minutes, or at 630°C with 300 sccm of silane for 3 minutes, or at 630°C with 1500 sccm of silane for 20 minutes, or at 630°C with 1500 sccm of silane for 20 minutes. Of course, the process conditions for forming the second polycrystalline silicon can be adjusted according to actual needs, and this embodiment does not impose specific limitations on this.

[0067] In some alternative embodiments, reference continues to be made to... Figure 1 , Figure 2 and Figure 5 The process involves phosphorus diffusion to transform the first polycrystalline silicon layer 05 into a first doped crystalline silicon layer 08 and the second polycrystalline silicon layer 07 into a second doped silicon layer 09, including:

[0068] At a temperature of 770 to 800°C, phosphorus oxychloride gas with a flow rate of 1000 to 2000 sccm was introduced, and deposition was carried out for 1500 to 2000 s; then the temperature was increased to 880 to 910°C, and oxygen gas with a flow rate of 500 to 1000 sccm was introduced, and deposition was carried out for 2000 to 4000 s.

[0069] It is understandable that phosphorus doping is effective by changing the process conditions. When testing the doped solar cell 100, the phosphorus doping curves of different regions in the first doped crystalline silicon layer 08 are basically consistent, and the phosphorus doping curves of different regions in the second doped polycrystalline silicon layer are also basically consistent.

[0070] In some alternative embodiments, reference continues to be made to... Figure 2 The phosphorus concentration in the first doped silicon layer 08 ranges from 1×E20 / cm. 3 Up to 5×E20 / cm 3The phosphorus concentration in the second doped silicon layer 09 ranges from 3 × E20 / cm³. 3 Up to 8×E20 / cm 3 .

[0071] It is understandable that the phosphorus concentration plateau of the first doped silicon layer 08 is the first concentration plateau, and the phosphorus concentration plateau of the second doped silicon layer 09 is the second concentration plateau. The second concentration plateau is higher than the first concentration plateau because the presence of the second silicon oxide layer 06 hinders the phosphorus diffusion process, thus helping to accurately control the degree of phosphorus diffusion.

[0072] In some alternative embodiments, reference continues to be made to... Figure 2 , Figure 3 and Figure 5 Removing the second doped silicon layer 09 includes:

[0073] A first mixed solution is formed by mixing a 3% to 8% potassium hydroxide solution with a 1% auxiliary etching solution. The sample is then immersed in the first mixed solution for 120 to 500 seconds at a temperature of 50 to 70°C.

[0074] Understandably, the second silicon oxide layer 06 reacts with acidic solutions but not with alkaline solutions, while the first doped silicon layer 08 and the second doped silicon layer 09 react with alkaline solutions but not with acidic solutions. Therefore, when removing the second doped layer, immersion in the first mixed solution at a temperature of 50 to 70°C for 120 to 500 seconds ensures complete removal of the second doped silicon layer 09. With the protection of the second silicon oxide layer 06, the first doped silicon layer 08 will not be damaged.

[0075] In some alternative embodiments, refer to Figure 1 and Figure 7 , Figure 7 This is a flowchart of the formation of the emitter 11 in the solar cell 100 provided by the present invention. Before the formation of the first silicon oxide layer 04 on the second surface 03, the process further includes:

[0076] S201: Texturing the first surface 02 of the silicon substrate 01;

[0077] S202: Boron diffusion is performed to form an emitter 11 and a borosilicate glass layer 12 stacked sequentially on the first surface 02, with the borosilicate glass layer 12 located on the side of the emitter 11 away from the silicon substrate 01.

[0078] It is understandable that cleaning and texturing the silicon substrate 01 can remove surface damage and form a pyramid light-trapping structure, increasing light absorption. However, the borosilicate glass layer 12 formed during boron diffusion can affect the characteristics of the solar cell 100, so it needs to be removed.

[0079] In some alternative embodiments, reference continues to be made to... Figure 2 and Figure 4 The second silicon oxide layer 06 is removed while the borosilicate glass layer 12 is also removed.

[0080] Understandably, removing both the second silicon oxide layer 06 and the borosilicate glass layer 12 simultaneously simplifies the process and saves time and costs.

[0081] In some alternative embodiments, reference continues to be made to... Figure 2 and Figure 4 Removing the second silicon oxide layer 06 and the borosilicate glass layer 12 includes:

[0082] Soak for 60 seconds using a hydrofluoric acid solution with a concentration of 1% to 5%.

[0083] It is understandable that the concentration of the hydrofluoric acid solution and the immersion time of the solar cell 100 in the hydrofluoric acid solution will affect the removal effect of the second silicon oxide layer 06 and the borosilicate glass layer 12. Using a hydrofluoric acid solution with a concentration of 1% to 5% and immersion for 60 seconds has a better effect, which helps the side of the emitter 11 away from the silicon substrate 01 and the side of the first doped crystalline silicon layer 08 away from the first silicon oxide layer 04 to achieve a hydrophobic effect. Of course, the concentration of the hydrofluoric acid solution and the immersion time of the solar cell 100 in the hydrofluoric acid solution can be adjusted according to actual needs, and this embodiment does not make specific limitations in this regard.

[0084] In some alternative embodiments, reference continues to be made to... Figure 1 Along the first direction X, the thickness of the first silicon oxide layer 04 ranges from 0.5 to 2 nm, the thickness of the first polysilicon layer 05 ranges from 10 to 80 nm, the thickness of the second silicon oxide layer 06 ranges from 0.5 to 2 nm, and the thickness of the second polysilicon layer 07 ranges from 20 to 100 nm.

[0085] It is understandable that, along the first direction X, if the thickness of the first silicon oxide layer 04 is greater than 2 nm, the first silicon oxide layer 04 may be close to insulation, making current transmission through the first silicon oxide layer 04 difficult; along the first direction X, if the thickness of the first polycrystalline silicon layer 05 is less than 10 nm, after phosphorus doping, the first polycrystalline silicon layer 05 is transformed into first doped polycrystalline silicon. If the first doped polycrystalline silicon is too thin, its passivation effect will also decrease, increasing the difficulty of matching subsequent metallization processes in the solar cell 100; along the first direction X, if the thickness of the second silicon oxide layer 06 is greater than 2 nm, the second polycrystalline silicon layer 05... If the thickness of layer 7 is greater than 100 nm, it will increase the cost. Therefore, it is preferable that along the first direction X, the thickness of the first silicon oxide layer 04 is in the range of 0.5 to 2 nm, the thickness of the first polysilicon layer 05 is in the range of 10 to 80 nm, the thickness of the second silicon oxide layer 06 is in the range of 0.5 to 2 nm, and the thickness of the second polysilicon layer 07 is in the range of 20 to 100 nm. Of course, it is not limited to this. The thicknesses of the first silicon oxide layer 04, the first polysilicon layer 05, the second silicon oxide layer 06, and the second polysilicon layer 07 can be set according to actual needs. This embodiment does not impose specific limitations on this.

[0086] In some alternative embodiments, refer to Figure 8 , Figure 8 This is a structural diagram of a photovoltaic module provided by the present invention, illustrating a specific embodiment of the photovoltaic module 200 provided by the present invention, including:

[0087] The solar cell 100 is manufactured using any of the methods described in the above embodiments.

[0088] The first adhesive film 13 is located on one side of the solar cell 100;

[0089] The second adhesive film 14 is located on the side of the solar cell 100 away from the first adhesive film 13;

[0090] The first glass 15 is located on the side of the first adhesive film 13 away from the solar cell 100;

[0091] The second glass 16 is located on the side of the second encapsulant film 14 away from the solar cell 100.

[0092] Understandably, for ease of illustration, in Figure 8 The first glass 15 and the second glass 16 are not patterned. The solar cell 100 in the photovoltaic module 200 provided in this embodiment is made using the preparation method of the solar cell 100 in the above embodiment, which has the beneficial effects of the preparation method of the solar cell 100 provided in this embodiment. For details, please refer to the specific description of the preparation method of the solar cell 100 in the above embodiments. This embodiment will not repeat it here.

[0093] As can be seen from the above embodiments, the method for preparing solar cells provided by the present invention achieves at least the following beneficial effects:

[0094] The method for fabricating a solar cell provided by the present invention includes: providing a silicon substrate, the silicon substrate including a first surface and a second surface disposed opposite to each other along a first direction; forming a first silicon oxide layer on the second surface; forming a first polycrystalline silicon layer on the side of the first silicon oxide layer away from the silicon substrate; forming a second silicon oxide layer on the side of the first polycrystalline silicon layer away from the silicon substrate; forming a second polycrystalline silicon layer on the side of the second silicon oxide layer away from the silicon substrate; performing phosphorus diffusion to convert the first polycrystalline silicon layer into a first doped crystalline silicon layer and the second polycrystalline silicon layer into a second doped crystalline silicon layer; and sequentially removing the second doped crystalline silicon layer and the second silicon oxide layer. By depositing a first polycrystalline silicon layer, a second silicon oxide layer, and a second polycrystalline silicon layer stacked on the back of a solar cell, the influence of deposition equipment uniformity can be reduced, phosphorus diffusion can be better matched, and it helps to form a uniform doped polycrystalline silicon layer. The presence of the second silicon oxide can improve the process window and further control the phosphorus diffusion process. When removing the second doped silicon layer, the second silicon oxide layer can also be used as a self-stopping layer for the reaction, avoiding damage to the first doped silicon layer and ensuring that the first doped silicon layer has a good passivation effect. Therefore, the solar cell fabrication method provided by this invention can reduce the thickness of the first doped silicon layer while ensuring the uniformity and passivation effect of the first doped silicon layer, thereby improving the characteristics of the solar cell.

[0095] While specific embodiments of the invention have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A method for preparing a solar cell, characterized in that, include: A silicon substrate is provided, the silicon substrate including a first surface and a second surface disposed opposite to each other along a first direction; A first silicon oxide layer is formed on the second surface; A first polycrystalline silicon layer is formed on the side of the first silicon oxide layer away from the silicon substrate; A second silicon oxide layer is formed on the side of the first polysilicon layer away from the silicon substrate; A second polycrystalline silicon layer is formed on the side of the second silicon oxide layer away from the silicon substrate; Phosphorus diffusion is performed to convert the first polycrystalline silicon layer into a first doped crystalline silicon layer and the second polycrystalline silicon layer into a second doped crystalline silicon layer. The second doped silicon layer and the second silicon oxide layer are removed sequentially.

2. The method for preparing a solar cell according to claim 1, characterized in that, The step of performing phosphorus diffusion to convert the first polycrystalline silicon layer into a first doped crystalline silicon layer and the second polycrystalline silicon layer into a second doped silicon layer further includes: A phosphosilicate glass layer is formed on the side of the second doped silicon layer away from the first doped silicon layer; The phosphorosilicate glass layer is removed before the second doped silicon layer is removed.

3. The method for preparing a solar cell according to claim 2, characterized in that, The removal of the phosphosilicate glass layer includes: Use a hydrofluoric acid solution with a concentration of 3% to 10% to immerse one side for 30 to 120 seconds.

4. The method for preparing a solar cell according to claim 1, characterized in that, The process conditions for forming the first silicon oxide layer on the second surface are as follows: Under temperature conditions of 570 to 630°C, oxygen was introduced at a flow rate of 30,000 to 40,000 sccm, and the deposition time ranged from 300 to 500 s.

5. The method for preparing a solar cell according to claim 1, characterized in that, The process conditions for forming the first polysilicon layer on the side of the first silicon oxide layer away from the silicon substrate are as follows: At temperatures ranging from 570 to 630°C, silane with a gas flow rate ranging from 300 to 1500 sccm was introduced, and the deposition time ranged from 2 to 15 minutes.

6. The method for preparing a solar cell according to claim 1, characterized in that, The process conditions for forming the second silicon oxide layer on the side of the first polycrystalline silicon layer away from the silicon substrate are as follows: Under temperature conditions of 570 to 630°C, oxygen was introduced at a flow rate of 30,000 to 40,000 sccm, and the deposition time ranged from 300 to 500 s.

7. The method for preparing a solar cell according to claim 1, characterized in that, The process conditions for forming the second polysilicon layer on the side of the second silicon oxide layer away from the silicon substrate are as follows: At temperatures ranging from 570 to 630°C, silane with a gas flow rate ranging from 300 to 1500 sccm was introduced, and the deposition time ranged from 3 to 20 minutes.

8. The method for preparing a solar cell according to claim 1, characterized in that, Phosphorus diffusion is performed to convert the first polycrystalline silicon layer into a first doped crystalline silicon layer and the second polycrystalline silicon layer into a second doped crystalline silicon layer, including: At a temperature of 770 to 800°C, phosphorus oxychloride gas with a flow rate of 1000 to 2000 sccm was introduced, and deposition was carried out for 1500 to 2000 s; then the temperature was increased to 880 to 910°C, and oxygen gas with a flow rate of 500 to 1000 sccm was introduced, and deposition was carried out for 2000 to 4000 s.

9. The method for preparing a solar cell according to claim 1, characterized in that, The phosphorus concentration in the first doped silicon layer is in the range of 1×E20 / cm. 3 Up to 5×E20 / cm 3 The phosphorus concentration in the second doped silicon layer ranges from 3 × E20 / cm³. 3 Up to 8×E20 / cm 3 .

10. The method for preparing a solar cell according to claim 1, characterized in that, The removal of the second doped silicon layer includes: A first mixed solution is formed by mixing a 3% to 8% potassium hydroxide solution with a 1% auxiliary etching solution. The sample is then immersed in the first mixed solution for 120 to 500 seconds at a temperature of 50 to 70°C.

11. The method for preparing a solar cell according to claim 1, characterized in that, Before forming the first silicon oxide layer on the second surface, the method further includes: The first surface of the silicon substrate is texturized; Boron diffusion is performed to form an emitter and a borosilicate glass layer stacked sequentially on the first surface.

12. The method for preparing a solar cell according to claim 11, characterized in that, The borosilicate glass layer is removed simultaneously with the removal of the second silicon oxide layer.

13. The method for preparing a solar cell according to claim 12, characterized in that, Removing the second silicon oxide layer and the borosilicate glass layer includes: Soak for 60 seconds using a hydrofluoric acid solution with a concentration of 1% to 5%.

14. The method for preparing a solar cell according to claim 1, characterized in that, Along the first direction, the thickness of the first silicon oxide layer ranges from 0.5 to 2 nm, the thickness of the first polycrystalline silicon layer ranges from 10 to 80 nm, the thickness of the second silicon oxide layer ranges from 0.5 to 2 nm, and the thickness of the second polycrystalline silicon layer ranges from 20 to 100 nm.

15. A photovoltaic module, characterized in that, include: A solar cell is manufactured using the solar cell manufacturing method according to any one of claims 1 to 14; The first adhesive film is located on one side of the solar cell; The second adhesive film is located on the side of the solar cell away from the first adhesive film; The first glass is located on the side of the first adhesive film away from the solar cell; The second glass is located on the side of the second encapsulant film away from the solar cell.

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