A method for preparing a solar cell, a solar cell and a photovoltaic module

Abstract

The present application relates to a method for preparing a solar cell, a solar cell and a photovoltaic module, including: performing boron diffusion on a first surface of a textured substrate to form a boron diffusion layer and a borosilicate glass layer with a thickness D1 satisfying 90 nm ≤ D1 ≤ 190 nm; depositing amorphous silicon or polycrystalline silicon on a second surface of the substrate to form a wrap-around coating; performing phosphorus diffusion on the second surface of the substrate to form a doped conductive layer, a first phosphosilicate glass layer with a thickness less than the thickness of the borosilicate glass layer is formed on a side of the wrap-around coating away from the substrate, and a boron phosphosilicate glass layer with a thickness less than or equal to the thickness of the borosilicate glass layer is formed in the borosilicate glass layer; using an acidic solution to remove the first phosphosilicate glass layer, the acidic solution includes a first solution, or a first solution and a first additive; using an alkaline solution to remove the wrap-around coating. The present application is beneficial to reducing the possibility of over-etching of the substrate and improving the production quality of the solar cell.

Description

Technical Field

[0001] This application relates to the technical field of solar cells, and particularly to a method for manufacturing a solar cell, a solar cell, and a photovoltaic module. Background Art

[0002] With the development of technology, the application fields of solar cells are becoming more and more extensive. In the production of solar cells, amorphous silicon or polycrystalline silicon is deposited on a substrate. At this time, a corresponding plating surface will also be generated on the substrate, and the plating surface needs to be removed to reduce the impact on the solar cell. Currently, over-etching is likely to occur when removing the plating surface, that is, the acidic solution or alkaline solution used will corrode the substrate, resulting in the destruction of the PN junction structure, thereby affecting the quality and performance of the solar cell. Summary of the Invention

[0003] This application provides a method for manufacturing a solar cell, a solar cell, and a photovoltaic module, which are used to solve the problem that over-etching is likely to occur during the production of solar cells.

[0004] An embodiment of this application provides a method for manufacturing a solar cell, including:

[0005] Performing boron diffusion on the first surface of the textured substrate, forming a boron diffusion layer and a borosilicate glass layer with a thickness D1 satisfying 90 nm ≤ D1 ≤ 190 nm on the first surface of the substrate;

[0006] Depositing amorphous silicon or polycrystalline silicon on the second surface of the substrate, and a plating layer is formed on the side of the borosilicate glass layer away from the substrate;

[0007] Performing phosphorus diffusion on the second surface of the substrate, a doped conductive layer is formed on the second surface, a first phosphosilicate glass layer with a thickness less than that of the borosilicate glass layer is formed on the side of the plating layer away from the substrate, and a boron phosphosilicate glass layer with a thickness less than or equal to that of the borosilicate glass layer is formed in the borosilicate glass layer;

[0008] Using an acidic solution to remove the first phosphosilicate glass layer, the acidic solution includes a first solution, or a first solution and a first additive, wherein the first additive is used to control the reaction rate of the acidic solution with the first phosphosilicate glass layer and the boron phosphosilicate glass layer;

[0009] Using an alkaline solution to remove the plating layer.

[0010] In a possible implementation manner, the step of performing phosphorus diffusion on the second surface of the substrate includes:

[0011] On the side of the coating layer away from the substrate, form the first phosphosilicate glass layer with a thickness D2 satisfying 35 nm ≤ D2 ≤ 40 nm.

[0012] In a possible implementation manner, the step of performing phosphorus diffusion on the second surface of the substrate includes:

[0013] Form the borophosphosilicate glass layer with a thickness of D3 in the borosilicate glass layer, and the ratio of the thickness D3 of the borophosphosilicate glass layer to the thickness D1 of the borosilicate glass layer satisfies 0.1 ≤ D3 / D1 ≤ 1.

[0014] In a possible implementation manner, the step of using an acidic solution to remove the first phosphosilicate glass layer includes:

[0015] Use the acidic solution to remove part of the borophosphosilicate glass layer, and after removal, the thickness D4 of the borophosphosilicate glass layer satisfies 1 nm ≤ D4 ≤ 50 nm.

[0016] In a possible implementation manner, the acidic solution includes a first solution, and the first solution is a hydrofluoric acid solution with a volume fraction of 1% to 10%.

[0017] In a possible implementation manner, the acidic solution includes a first solution, and the first solution is a mixed solution of hydrofluoric acid and ammonium fluoride with a volume fraction of 1% to 10%, wherein the volume ratio of ammonium fluoride to hydrofluoric acid is (4 - 7):1.

[0018] In a possible implementation manner, the acidic solution includes a first solution and a first additive, and the mass fraction ratio of the first solution to the first additive is 1:2 to 8:1, wherein the first solution is a hydrofluoric acid solution with a volume fraction of 1% to 20%.

[0019] In a possible implementation manner, the acidic solution includes a first solution and a first additive, and the mass fraction ratio of the first solution to the first additive is 1:2 to 8:1, wherein the first solution is a mixed solution of hydrofluoric acid and ammonium fluoride with a volume fraction of 1% to 20%.

[0020] In a possible implementation manner, the step of performing phosphorus diffusion on the second surface of the substrate includes:

[0021] Form a second phosphosilicate glass layer on the side of the doped conductive layer away from the substrate.

[0022] In a possible implementation, the alkaline solution includes a second solution and a second additive, and the mass fraction ratio of the second solution to the second additive is 6:1 to 20:1. Among them, the second solution includes at least one of potassium hydroxide, sodium hydroxide, and ammonia hydroxide, and the second additive is used to control the reaction rate between the alkaline solution and the second phosphosilicate glass layer.

[0023] In a possible implementation, after the step of using the alkaline solution to remove the overplating layer, the method for manufacturing the solar cell further includes:

[0024] Using a cleaning solution to remove the borosilicate glass layer, the borophosphosilicate glass layer on the first surface, and the second phosphosilicate glass layer on the second surface, where the cleaning solution includes at least one of hydrofluoric acid and hydrochloric acid.

[0025] In a possible implementation, after the step of using the cleaning solution to remove the borosilicate glass layer, the borophosphosilicate glass layer on the first surface, and the second phosphosilicate glass layer on the second surface, the method for manufacturing the solar cell further includes:

[0026] Preparing a passivation layer on the first surface and the second surface;

[0027] Forming electrodes on the first surface and the second surface.

[0028] The embodiments of the present application also provide a solar cell, which is manufactured by the method for manufacturing a solar cell in any one of the above.

[0029] The embodiments of the present application also provide a photovoltaic module, including at least one battery string, a packaging layer, and a cover plate. The battery string is composed of the above-mentioned solar cells electrically connected, the packaging layer is used to cover the surface of the battery string, and the cover plate is used to cover the surface of the packaging layer away from the battery string.

[0030] The embodiments of the present application provide a preparation method of a solar cell, a solar cell and a photovoltaic module. The preparation method of the solar cell includes: performing boron diffusion on the first surface of the textured substrate, forming a boron diffusion layer and a borosilicate glass layer with a thickness D1 satisfying 90 nm ≤ D1 ≤ 190 nm on the first surface of the substrate; depositing amorphous silicon or polycrystalline silicon on the second surface of the substrate, forming a wrap-around coating on the side of the borosilicate glass layer away from the substrate; performing phosphorus diffusion on the second surface of the substrate, forming a doped conductive layer on the second surface, forming a first phosphosilicate glass layer with a thickness less than that of the borosilicate glass layer on the side of the wrap-around coating away from the substrate, and forming a boron phosphosilicate glass layer with a thickness less than or equal to that of the borosilicate glass layer in the borosilicate glass layer; using an acidic solution to remove the first phosphosilicate glass layer, the acidic solution includes a first solution, or a first solution and a first additive, wherein the first additive is used to control the reaction rate of the acidic solution with the first phosphosilicate glass layer and the boron phosphosilicate glass layer; using an alkaline solution to remove the wrap-around coating. In the embodiments of the present application, by increasing the thickness of the borosilicate glass layer, the thickness of the phosphorus borosilicate glass layer can be increased, which is beneficial to reducing the possibility of over-etching on the first surface caused by the acidic solution completely corroding the phosphorus borosilicate glass layer, and thus is beneficial to improving the production quality of the solar cell.

[0031] It should be understood that the above general description and the following detailed description are only exemplary and do not limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a flowchart of a preparation method of a solar cell provided by an embodiment of the present application;

[0033] Figure 2 is a schematic diagram of a solar cell in the first embodiment of the preparation method of a solar cell provided by an embodiment of the present application;

[0034] Figure 3 is a schematic diagram of a solar cell in the second embodiment of the preparation method of a solar cell provided by an embodiment of the present application;

[0035] Figure 4 is a schematic diagram of a solar cell in the third embodiment of the preparation method of a solar cell provided by an embodiment of the present application;

[0036] Figure 5 is a schematic diagram of a photovoltaic module provided by an embodiment of the present application.

[0037] REFERENCE SIGNS:

[0038] 1 - Substrate;

[0039] 11 - First surface;

[0040] 12 - Second surface;

[0041] 2 - Borosilicate glass layer;

[0042] 3 - Winding coating;

[0043] 4 - First phosphosilicate glass layer;

[0044] 5 - Borophosphosilicate glass layer;

[0045] 6 - Doped conductive layer;

[0046] 7 - Second phosphosilicate glass layer;

[0047] 8 - Boron diffusion layer;

[0048] 9 - Tunneling layer;

[0049] 10 - Solar cell;

[0050] 100 - Battery string;

[0051] 200 - Encapsulation layer;

[0052] 300 - Cover plate.

[0053] The accompanying drawings herein are incorporated into and constitute a part of this specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application. Detailed implementation manners

[0054] For a better understanding of the technical solutions of the present application, the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0055] It should be clear that the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the scope of protection of the present application.

[0056] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The singular forms of "a", "the" and "said" used in the embodiments of the present application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0057] It should be understood that the term " / and / " used herein is only a description of the associated relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0058] It should be noted that the orientation terms such as "upper", "lower", "left", and "right" described in the embodiments of the present application are described from the angles shown in the drawings, and should not be construed as limitations on the embodiments of the present application. In addition, in the context, it should also be understood that when it is mentioned that one element is connected "above" or "below" another element, it can not only be directly connected "above" or "below" another element, but also be indirectly connected "above" or "below" another element through an intermediate element.

[0059] As Figures 1 to 4 shown, the embodiments of the present application provide a method for preparing a solar cell 10, including:

[0060] S1. Perform boron diffusion on the first surface 11 of the textured substrate 1, and a boron diffusion layer 8 and a borosilicate glass layer 2 with a thickness D1 satisfying 90 nm ≤ D1 ≤ 190 nm are formed on the first surface 11 of the substrate 1;

[0061] S2. Deposit amorphous silicon or polycrystalline silicon on the second surface 12 of the substrate 1, and a wrap-around coating layer 3 is formed on the side of the borosilicate glass layer 2 away from the substrate 1;

[0062] S3. Perform phosphorus diffusion on the second surface 12 of the substrate 1, a doped conductive layer 6 is formed on the second surface 12, a first phosphosilicate glass layer 4 with a thickness less than that of the borosilicate glass layer 2 is formed on the side of the wrap-around coating layer 3 away from the substrate 1, and a boron phosphosilicate glass layer 5 with a thickness less than or equal to that of the borosilicate glass layer 2 is formed in the borosilicate glass layer 2;

[0063] S4. Use an acidic solution to remove the first phosphosilicate glass layer 4, the acidic solution includes a first solution, or a first solution and a first additive, wherein the first additive is used to control the reaction rate of the acidic solution with the first phosphosilicate glass layer 4 and the boron phosphosilicate glass layer 5;

[0064] S5. Use an alkaline solution to remove the wrap-around coating layer 3.

[0065] The solar cell 10 has a silicon substrate, and the silicon substrate includes but is not limited to a single-crystalline silicon substrate, a polycrystalline silicon substrate, a quasi-single-crystalline silicon substrate, etc. The substrate 1 has a first surface 11 and a second surface 12 that are oppositely arranged in the thickness direction. Among them, the first surface 11 can be a light receiving surface facing the sun, and the second surface 12 can be the back surface of the solar cell 10. The substrate 1 can be textured before the S1 step. The texturing treatment is beneficial to reducing the reflectivity of the surface of the substrate 1, thereby being beneficial to the solar cell 10 obtaining a higher photoelectric conversion efficiency. As Figure 2As shown, in step S1, after boron diffusion, a boron diffusion layer 8 and a borosilicate glass layer 2 are sequentially formed on the first surface 11 in a direction away from the substrate 1. Among them, the boron diffusion layer 8 can form a PN junction structure with the substrate 1. The thickness of the borosilicate glass layer 2 can be 90 nm, 100 nm, 120 nm, 150 nm, or 190 nm. Of course, it can also be other values within the above range, which is not limited here.

[0066] As Figure 2 shown, in step S2, amorphous silicon or polycrystalline silicon can be deposited on the second surface 12 by using Low Pressure Chemical Vapor Deposition (LPCVD) or Plasma Enhanced Chemical Vapor Deposition (PECVD). The second surface 12 is the target deposition surface, while the first surface 11 is the non-target deposition surface. During the deposition process, when depositing on the second surface 12, amorphous silicon or polycrystalline silicon will also be deposited on the first surface 11 accordingly. This phenomenon can be called the overplating phenomenon, that is, an overplated amorphous silicon layer or an overplated polycrystalline silicon layer is formed on the side of the borosilicate glass layer 2 away from the substrate 1. And these formed overplated layers 3 need to be removed in subsequent steps to reduce the possibility of the overplated layers 3 affecting the battery efficiency and quality.

[0067] As Figure 2 shown, in step S3, the second surface 12 is the target diffusion surface for phosphorus diffusion, while the first surface 11 is the non-target diffusion surface. After phosphorus diffusion, the amorphous silicon or polycrystalline silicon deposited on the second surface 12 is doped with phosphorus elements, so that a doped conductive layer 6 can be formed. The doped conductive layer 6 can form a band bending on the surface of the substrate 1 to achieve selective transport of carriers and reduce recombination losses. At the same time, after phosphorus diffusion, a second phosphosilicate glass layer 7 is also formed on the side of the doped conductive layer 6 away from the substrate 1, while a first phosphosilicate glass layer 4 and a borophosphosilicate glass layer 5 are formed on the first surface 11. This phenomenon of phosphorus diffusing to the first surface 11 can be called the over-diffusion phenomenon. Among them, the borophosphosilicate glass layer 5 is formed because phosphorus diffuses into the borosilicate glass layer 2, and the thickness of the borophosphosilicate glass layer 5 is related to the depth of phosphorus diffusion. The thickness of the borophosphosilicate glass layer 5 can be the same as that of the borosilicate glass layer 2, or it can also be smaller than the borosilicate glass layer 2.

[0068] The first phosphosilicate glass layer 4 generated by the edge expansion can be removed by using an acidic solution in step S4. The acidic solution can be a low-concentration hydrofluoric acid solution or a low-concentration buffered hydrofluoric acid solution. On the first surface 11, the corrosion resistance of the borosilicate glass layer 2 is relatively high, while the corrosion resistance of the borophosphosilicate glass layer 5 formed in the borosilicate glass layer 2 after phosphorus diffusion is relatively low. Therefore, as Figure 3 shown, in step S4, the acidic solution can corrode both the first phosphosilicate glass layer 4 and the borophosphosilicate glass layer 5. Since the concentration of the acidic solution is low, the corrosion rates of the borophosphosilicate glass layer 5 and the first phosphosilicate glass layer 4 are slow. At the same time, since a relatively thick borosilicate glass layer 2 is formed in step S1, the borophosphosilicate glass layer 5 formed after phosphorus diffusion can also have a relatively large thickness. Also, since the thickness of the first phosphosilicate glass layer 4 is relatively small, after the acidic solution corrodes the first phosphosilicate glass layer 4 at a slow rate, the borophosphosilicate glass layer 5 can still remain because of its relatively large thickness and slow reaction rate with the acidic solution. This reduces the possibility of the acidic solution penetrating the borophosphosilicate glass layer 5 and corroding the substrate 1, thereby reducing the possibility of the PN junction structure being damaged. The acidic solution can also include a first additive, and the first additive can be used to control the reaction rates of the first phosphosilicate glass layer 4 and the borophosphosilicate glass layer 5. Specifically, the first additive can further slow down the reaction rate of the acidic solution with the borophosphosilicate glass layer 5, so that when the acidic solution removes the first phosphosilicate glass layer 4, a certain thickness of the borophosphosilicate glass layer 5 can still be retained.

[0069] As Figure 4 shown, in step S5, an alkaline solution can be used to remove the edge plating layer 3. At this time, since the borophosphosilicate glass layer 5 still remains on the first surface 11, the borophosphosilicate glass layer 5 can protect the boron diffusion layer 8, reducing the possibility of the alkaline solution damaging the boron diffusion layer 8 and the structure of the substrate 1, which is beneficial to improving the stability of the PN junction structure and further beneficial to improving the production quality of the entire solar cell 10.

[0070] In the related art, usually, a mask layer, an acidic solution or an alkaline solution can be used to remove the edge plating layer. However, this method has a high cost. Or, the mask layer can be not used, and the acidic solution or the alkaline solution can be directly used to remove the edge plating layer. In this process, over-etching is likely to occur to the substrate by the acidic solution or the alkaline solution, that is, since a borophosphosilicate glass layer will be formed in the borosilicate glass layer during phosphorus diffusion and the corrosion resistance of the borophosphosilicate glass layer is poor, the acidic solution or the alkaline solution is likely to corrode the entire borophosphosilicate glass layer, further damaging the structures such as the boron diffusion layer on the first surface and even damaging the PN junction structure of the solar cell, thereby affecting the quality and performance of the entire solar cell.

[0071] Compared with the prior art, in the embodiment of the present application, by increasing the thickness of the borosilicate glass layer 2, the thickness of the phospho-borosilicate glass layer 2 can be increased, reducing the possibility that the acidic solution completely corrodes the phospho-borosilicate glass layer 2 in step S4, so that a certain thickness of the phospho-borosilicate glass layer 2 can be retained. At the same time, by using an acidic solution with a lower concentration, it is beneficial to slow down the reaction rate of the phospho-borosilicate glass layer 2 and the first phosphosilicate glass layer 4. Further, a first additive can be used to slow down the reaction rate of the phospho-borosilicate glass layer 2, which is beneficial to reducing the possibility that the acidic solution completely corrodes the phospho-borosilicate glass layer 2 and causes over-etching on the first surface 11, and thus is beneficial to improving the production quality of the solar cell 10. On the other hand, the process involved in the preparation method of the solar cell 10 provided in the embodiment of the present application is relatively simple, and the original process flow is not changed, so this preparation method is suitable for large-scale production.

[0072] In a possible implementation manner, step S3 includes: S31, forming a first phosphosilicate glass layer 4 with a thickness D2 satisfying 35 nm ≤ D2 ≤ 45 nm on one side of the coating layer 3 away from the substrate 1.

[0073] The thickness of the first phosphosilicate glass layer 4 can be 35 nm, 38 nm, 40 nm, 42 nm or 45 nm, or other values within the above range, which are not limited herein.

[0074] By limiting the thickness of the first phosphosilicate glass layer 4, the first phosphosilicate glass layer 4 can be made thinner than the borosilicate glass layer 2, so that the thickness of the first phosphosilicate glass layer 4 can be thinner than that of the phospho-borosilicate glass layer 2. When the acidic solution removes the first phosphosilicate glass layer 4, since the thickness of the first phosphosilicate glass layer 4 is smaller and the thickness of the phospho-borosilicate glass layer 2 is larger, after the acidic solution completely corrodes the first phosphosilicate glass layer 4, a part of the phospho-borosilicate glass layer 2 can still be retained, and the phospho-borosilicate glass layer 2 can protect the first surface 11, which is beneficial to reducing the possibility of over-etching on the first surface 11, and thus is beneficial to improving the production quality of the solar cell 10.

[0075] In a possible implementation manner, step S3 includes: S32, forming a borophosphosilicate glass layer 5 with a thickness of D3 in the borosilicate glass layer 2, and the ratio of the thickness D3 of the borophosphosilicate glass layer 5 to the thickness D1 of the borosilicate glass layer 2 satisfies 0.1 ≤ D3 / D1 ≤ 1.

[0076] The ratio of D3 / D1 can be 0.1, 0.3, 0.5, 0.6, or 1, or other values within the above range, which are not limited herein.

[0077] By limiting the thickness of the borophosphosilicate glass layer 5, it is beneficial to ensure that there is still some remaining borophosphosilicate glass layer 5 after reacting with the acidic solution, which is conducive to realizing the protective effect of the borophosphosilicate glass layer 5 on the phosphorus diffusion layer and the substrate 1, thereby reducing the possibility of over-etching occurring on the first surface 11 and being beneficial to improving the production quality of the solar cell 10.

[0078] In a possible implementation manner, the steps of S4 include: S41, using an acidic solution to remove a part of the borophosphosilicate glass layer 5, and after removal, the thickness D4 of the borophosphosilicate glass layer 5 satisfies 1nm ≤ D4 ≤ 50nm.

[0079] The value of D4 can be 1nm, 10nm, 20nm, 30nm or 50nm, or other values within the above range, which are not limited here.

[0080] After the acidic solution reacts with the borosilicate glass layer 5, the borosilicate glass layer 5 can still be retained. Retaining a certain thickness of the borophosphosilicate glass layer 5 can play a protective role on the phosphorus diffusion layer and the substrate 1, reducing the possibility of the acidic solution or the alkaline solution damaging the structure of the phosphorus diffusion layer and the substrate 1, thereby reducing the possibility of the PN junction structure being damaged.

[0081] In a possible implementation manner, the acidic solution includes a first solution, and the first solution is a hydrofluoric acid solution with a volume fraction of 1% to 10%.

[0082] Specifically, the volume fraction of the hydrofluoric acid solution can be 1%, 3%, 5%, 8% or 10%, and of course, it can also be other values within the above range, which are not limited here. In the step of S4, the first surface 11, that is, the single-sided plating surface, can be placed in the acidic solution so that the acidic solution can remove the first phosphosilicate glass layer 4 on the first surface 11. The reaction time can be within 10s to 180s, and the reaction temperature can be within 20°C to 25°C. During this process, since the second surface 12 is not placed in the acidic solution, the second phosphosilicate glass layer 7 on the second surface 12 is retained.

[0083] While setting the thickness of the first phosphosilicate glass layer 4 to be less than the thickness of the phosphoborosilicate glass layer 2, by using a low-concentration hydrofluoric acid solution, it is beneficial to slow down the reaction rate of the acidic solution with the phosphoborosilicate glass layer 2 and the first phosphosilicate glass layer 4, thereby further reducing the possibility of the acidic solution completely corroding the phosphoborosilicate glass layer 2, and further reducing the possibility of the PN junction structure being damaged due to over-etching on the first surface 11.

[0084] In a possible implementation manner, the acidic solution includes a first solution, and the first solution is a mixed solution of hydrofluoric acid and ammonium fluoride with a volume fraction of 1% to 10%, wherein the volume ratio of ammonium fluoride to hydrofluoric acid is (4 - 7):1.

[0085] A buffered hydrofluoric acid solution can be obtained by mixing hydrofluoric acid and ammonium fluoride. Specifically, the volume fraction after mixing hydrofluoric acid and ammonium fluoride can be 1%, 2%, 6%, 9% or 10%, or other values within the above range, which are not limited herein. In the buffered hydrofluoric acid solution, the volume ratio of ammonium fluoride to hydrofluoric acid is 4:1, 6:1 or 7:1, or other values within the above range, which are not limited herein. The reaction time of the buffered hydrofluoric acid solution with the first phosphosilicate glass layer 4 can be from 10 s to 180 s, and the reaction temperature is from 20 °C to 25 °C.

[0086] While setting the thickness of the first phosphosilicate glass layer 4 to be less than the thickness of the phosphoborosilicate glass layer 2, by using a low-concentration buffered hydrofluoric acid solution, it is beneficial to slow down the reaction rate of the acidic solution with the phosphoborosilicate glass layer 2 and the first phosphosilicate glass layer 4, thereby further reducing the possibility of the acidic solution completely corroding the phosphoborosilicate glass layer 2, and further reducing the possibility of the PN junction structure being damaged due to over-etching on the first surface 11.

[0087] In a possible implementation, the acidic solution includes a first solution and a first additive, and the mass fraction ratio of the first solution to the first additive is from 1:2 to 8:1, wherein the first solution is a hydrofluoric acid solution with a volume fraction of 1% to 20%.

[0088] The acidic solution can include a hydrofluoric acid solution and a first additive. The first additive can further slow down the reaction rate of the acidic solution with the borophosphosilicate glass layer 5, that is, it is beneficial to make the reaction rate of the borophosphosilicate glass layer 5 less than the reaction rate of the first phosphosilicate glass layer 4, so that when the acidic solution removes the first phosphosilicate glass layer 4, a certain thickness of the borophosphosilicate glass layer 5 can still be retained. In the acidic solution with the first additive added, the volume fraction of the hydrofluoric acid solution can be 1%, 5%, 10%, 12%, 15% or 20%. In this step, the reaction time is from 10 s to 180 s, and the reaction temperature is from 20 °C to 25 °C.

[0089] In a possible implementation, the acidic solution includes a first solution and a first additive, and the mass fraction ratio of the first solution to the first additive is from 1:2 to 8:1, wherein the first solution is a mixed solution of hydrofluoric acid and ammonium fluoride with a volume fraction of 1% to 20%.

[0090] The acidic solution can include a buffered hydrofluoric acid solution and a first additive. Similarly, by using the first additive, the reaction rate of the acidic solution with the borophosphosilicate glass layer 5 can be slowed down. In the acidic solution with the first additive added, the volume fraction after mixing hydrofluoric acid and ammonium fluoride can be 1%, 5%, 10%, 12%, 15% or 20%. In this step, the reaction time is from 10 s to 180 s, and the reaction temperature is from 20 °C to 25 °C.

[0091] In a possible implementation, step S3 includes: forming a second phosphosilicate glass layer 7 on the side of the doped conductive layer 6 away from the substrate 1.

[0092] During phosphorus diffusion, the second surface 12 is the target diffusion surface, and phosphorus atoms can diffuse into the amorphous silicon or polycrystalline silicon deposited on the second surface 12, thereby forming the doped conductive layer 6, and a second phosphosilicate glass layer 7 is formed on one side of the doped conductive layer 6. In step S5, the substrate 1 can be placed in an alkaline solution to remove the overcoat layer 3 on the first surface 11. At this time, the second phosphosilicate glass layer 7 can protect the doped conductive layer 6 and reduce the possibility of the doped conductive layer 6 being corroded by the alkaline solution.

[0093] In a possible implementation, the alkaline solution includes a second solution and a second additive, and the mass fraction ratio of the second solution to the second additive is 6:1 to 20:1. Among them, the second solution includes at least one of potassium hydroxide, sodium hydroxide, and ammonia hydroxide, and the second additive is used to control the reaction rate between the alkaline solution and the second phosphosilicate glass layer 7.

[0094] The second solution can be any one of a potassium hydroxide solution, a sodium hydroxide solution, and an ammonia hydroxide solution, or a combination of multiple ones. Among them, the volume fraction of the potassium hydroxide solution, the sodium hydroxide solution, and the ammonia hydroxide solution can be 4% to 7%. The function of the second additive is to slow down the reaction rate between the alkaline solution and the second phosphosilicate glass layer 7. When using the alkaline solution to remove the overcoat layer 3, the second phosphosilicate glass layer 7 can protect the doped conductive layer 6 and reduce the possibility of the doped conductive layer 6 being corroded by the alkaline solution. Specifically, the second additive can include components such as surfactants, defoamers, complexing agents, protective agents, and accelerators. More specifically, the second additive can include components such as sorbic acid esters, polyvinyl alcohol, alkyl glycosides, sodium acetate, and acetone. In the alkaline solution, the volume ratio of the second solution to the second additive can be between 4:1 and 7:1. In step S5, the substrate 1 can be placed in the alkaline solution, the reaction time is 180 s to 480 s, and the reaction temperature is 60 °C to 80 °C.

[0095] In a possible implementation, after step S5, the method for manufacturing the solar cell 10 further includes:

[0096] S6, using a cleaning solution to remove the borosilicate glass layer 2, the borophosphosilicate glass layer 5 on the first surface 11, and the second phosphosilicate glass layer 7 on the second surface 12. The cleaning solution includes at least one of hydrofluoric acid and hydrochloric acid.

[0097] The cleaning solution can be hydrofluoric acid or hydrochloric acid, or a mixed solution of hydrofluoric acid and hydrochloric acid. In this step, the cleaning solution can be used to remove the borosilicate glass layer 2, the borophosphosilicate glass layer 5, and the second phosphosilicate glass layer 7, and the cleaning solution can also remove the metal ions remaining in the S5 step, preparing for subsequent steps such as preparing the passivation layer, which is beneficial to improving the production quality of the solar cell 10.

[0098] In a possible implementation, after the S6 step, the method for preparing the solar cell 10 further includes:

[0099] S7, preparing a passivation layer on the first surface 11 and the second surface 12;

[0100] S8, forming electrodes on the first surface 11 and the second surface 12.

[0101] The passivation layer can passivate the surface of the substrate 1, which is beneficial to improving the performance of the solar cell 10. Specifically, the first passivation film can include components such as silicon nitride and aluminum oxide. The electrodes can be formed by metallization, such as forming electrodes by screen-printing conductive paste, and the electrodes can be electrically connected to the substrate 1.

[0102] The embodiment of the present application also provides a solar cell 10, which is prepared by the method for preparing the solar cell 10 in any one of the above.

[0103] In the solar cell 10, the second surface 12 may further have a tunneling layer 9, and the tunneling layer 9 is on the side of the doped conductive layer 6 close to the substrate 1. Specifically, the tunneling layer 9 can be a silicon oxide layer, which can chemically passivate the surface of the substrate 1, thus being beneficial to reducing interface states.

[0104] As Figure 5 shown, the embodiment of the present application also provides a photovoltaic module, including: at least one battery string 100, a packaging layer 200, and a cover plate 300. Among them, the battery string 100 is composed of a plurality of the above-mentioned solar cells 10 electrically connected, the packaging layer 200 is used to cover the surface of the battery string 100, and the cover plate 300 is used to cover the surface of the packaging layer 200 away from the battery string 100.

[0105] In the battery string 100, a plurality of solar cells 10 are electrically connected in series and / or in parallel. Through a lamination process, the cover plate 300, the packaging layer 200, and the battery string 100 can be pressed in a certain order to obtain a laminated module, and a frame can be installed on the laminated module subsequently to form a photovoltaic module. The photovoltaic module can play a role in photoelectric conversion through the battery string 100, that is, it can convert the light energy absorbed by the solar cell 10 into electrical energy.

[0106] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A method for preparing a solar cell, characterized in that, Including: Diffusing boron on the first surface (11) of the textured substrate (1), a boron diffusion layer (8) and a borosilicate glass layer (2) with a thickness D1 satisfying 90 nm ≤ D1 ≤ 190 nm are formed on the first surface (11) of the substrate (1); Depositing amorphous silicon or polycrystalline silicon on the second surface (12) of the substrate (1), a wrap-around coating layer (3) is formed on the side of the borosilicate glass layer (2) away from the substrate (1); Diffusing phosphorus on the second surface (12) of the substrate (1), a doped conductive layer (6) is formed on the second surface (12), a first phosphosilicate glass layer (4) with a thickness less than that of the borosilicate glass layer (2) is formed on the side of the wrap-around coating layer (3) away from the substrate (1), and a boron phosphosilicate glass layer (5) with a thickness less than or equal to that of the borosilicate glass layer (2) is formed in the borosilicate glass layer (2); Removing the first phosphosilicate glass layer (4) using an acidic solution, the acidic solution includes a first solution, or a first solution and a first additive, wherein the first additive is used to control the reaction rate of the acidic solution with the first phosphosilicate glass layer (4) and the boron phosphosilicate glass layer (5); Removing the wrap-around coating layer (3) using an alkaline solution; The step of removing the first phosphosilicate glass layer (4) using an acidic solution includes: Removing part of the boron phosphosilicate glass layer (5) using the acidic solution, and after removal, the thickness D4 of the boron phosphosilicate glass layer (5) satisfies 1 nm ≤ D4 ≤ 50 nm.

2. The manufacturing method of the solar cell according to claim 1, characterized in that, The step of diffusing phosphorus on the second surface (12) of the substrate (1) includes: Forming the first phosphosilicate glass layer (4) with a thickness D2 satisfying 35 nm ≤ D2 ≤ 40 nm on the side of the wrap-around coating layer (3) away from the substrate (1).

3. The manufacturing method of the solar cell according to claim 2, characterized in that, The step of diffusing phosphorus on the second surface (12) of the substrate (1) includes: Forming the boron phosphosilicate glass layer (5) with a thickness of D3 in the borosilicate glass layer (2), and the ratio of the thickness D3 of the boron phosphosilicate glass layer (5) to the thickness D1 of the borosilicate glass layer (2) satisfies 0.1 ≤ D3 / D1 ≤ 1.

4. The manufacturing method of the solar cell according to claim 1, wherein, The acidic solution includes a first solution, and the first solution is a hydrofluoric acid solution with a volume fraction of 1% to 10%.

5. The manufacturing method of the solar cell according to claim 1, characterized in that, The acidic solution includes a first solution, and the first solution is a mixed solution of hydrofluoric acid and ammonium fluoride with a volume fraction of 1% to 10%, wherein the volume ratio of ammonium fluoride to hydrofluoric acid is (4~7):

1.

6. The method for preparing a solar cell according to claim 1, wherein, The acidic solution includes a first solution and a first additive, and the mass fraction ratio of the first solution to the first additive is 1:2 to 8:1, wherein the first solution is a hydrofluoric acid solution with a volume fraction of 1% to 20%.

7. The preparation method of the solar cell according to claim 1, characterized in that, The acidic solution includes a first solution and a first additive, and the mass fraction ratio of the first solution to the first additive is 1:2 to 8:1, wherein the first solution is a mixed solution of hydrofluoric acid and ammonium fluoride with a volume fraction of 1% to 20%.

8. The manufacturing method of the solar cell according to any one of claims 1 to 7, characterized in that, The step of diffusing phosphorus on the second surface (12) of the substrate (1) includes: A second phosphosilicate glass layer (7) is formed on a side of the doped conductive layer (6) away from the substrate (1).

9. The manufacturing method of a solar cell according to claim 8, characterized in that, The alkaline solution includes a second solution and a second additive, and a mass fraction ratio of the second solution to the second additive is from 6:1 to 20:

1. Wherein, the second solution includes at least one of potassium hydroxide, sodium hydroxide, and ammonium hydroxide, and the second additive is used to control a reaction rate between the alkaline solution and the second phosphosilicate glass layer (7).

10. The manufacturing method of the solar cell according to claim 9, characterized in that, After the step of removing the overcoating layer (3) using the alkaline solution, the method for manufacturing the solar cell (10) further includes: using a cleaning solution to remove the borosilicate glass layer (2), the boron phosphosilicate glass layer (5) on the first surface (11), and the second phosphosilicate glass layer (7) on the second surface (12), where the cleaning solution includes at least one of hydrofluoric acid and hydrochloric acid.

11. The manufacturing method of the solar cell according to claim 10, characterized in that, After the step of using a cleaning solution to remove the borosilicate glass layer (2), the boron phosphosilicate glass layer (5) on the first surface (11), and the second phosphosilicate glass layer (7) on the second surface (12), the method for manufacturing the solar cell (10) further includes: preparing a passivation layer on the first surface (11) and the second surface (12); forming electrodes on the first surface (11) and the second surface (12).

12. A solar cell, characterized in that, The solar cell (10) is manufactured by the method for manufacturing the solar cell (10) according to any one of claims 1 to 11.

13. A photovoltaic module, characterized in that, including: at least one cell string (100), the cell string (100) being electrically connected and composed of a plurality of the solar cells (10) according to claim 12; a packaging layer (200) for covering a surface of the cell string (100); a cover plate (300) for covering a surface of the packaging layer (200) away from the cell string (100).

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