Solar cell preparation method and solar cell

Abstract

The invention relates to a solar cell preparation method and a solar cell. The solar cell preparation method comprises the steps of sequentially depositing a tunneling oxide layer, an intrinsic polycrystalline silicon layer, a reflecting layer and a mask layer on the surface of a substrate; removing a part of the reflecting layer and a part of the mask layer to expose a part of the intrinsic polycrystalline silicon layer; doping the exposed part of the intrinsic polycrystalline silicon layer to form a first doped polycrystalline silicon layer; removing the rest of the reflecting layer and the rest of the mask layer to expose the rest of the intrinsic polycrystalline silicon layer; doping the other exposed intrinsic polycrystalline silicon layer to form a second doped polycrystalline silicon layer; the doping type of the second doped polycrystalline silicon layer is different from that of the first doped polycrystalline silicon layer; and preparing passivation anti-reflection layers on the surfaces, deviating from the tunneling oxide layer, of the first doped polycrystalline silicon layer and the second doped polycrystalline silicon layer. No laser loss can be realized, in addition, the tunneling oxide layer and the intrinsic polycrystalline silicon layer only need to be deposited once, the reflecting layer and the mask layer can be deposited together with the polycrystalline silicon layer at the same time, the process time is greatly shortened, and the production cost is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of solar cell preparation, and in particular to a solar cell preparation method and a solar cell. Background Art

[0002] In the process of preparing solar cells, it is inevitable to use laser to open the film. However, the laser will damage other film layers in the solar cell that do not need to be opened, thereby affecting the conversion efficiency of the solar cell. Summary of the invention

[0003] Based on this, it is necessary to provide a solar cell preparation method and a solar cell that can avoid laser damage in order to solve the above technical problems.

[0004] In a first aspect, the present application provides a method for preparing a solar cell, the method comprising:

[0005] Depositing a tunneling oxide layer, an intrinsic polysilicon layer, a reflective layer and a mask layer in sequence on the surface of the substrate;

[0006] removing part of the reflective layer and part of the mask layer to expose part of the intrinsic polysilicon layer;

[0007] doping the exposed portion of the intrinsic polysilicon layer to form a first doped polysilicon layer;

[0008] removing the remaining reflective layer and the remaining mask layer to expose the remaining intrinsic polysilicon layer; the remaining reflective layer and part of the reflective layer constitute the entire reflective layer, the remaining mask layer and part of the mask layer constitute the entire mask layer, and the remaining intrinsic polysilicon layer and part of the intrinsic polysilicon layer constitute the entire intrinsic polysilicon layer;

[0009] doping the remaining exposed intrinsic polysilicon layer to form a second doped polysilicon layer; the doping type of the second doped polysilicon layer is different from that of the first doped polysilicon layer;

[0010] A passivation anti-reflection layer is formed on a side of the first doped polysilicon layer and the second doped polysilicon layer away from the tunnel oxide layer.

[0011] In one embodiment, removing part and the rest of the mask layer comprises:

[0012] A portion and the rest of the mask layer are removed by a preset laser; the preset laser corresponds to the refractive index of the reflective layer.

[0013] In one embodiment, depositing the reflective layer on a side of the intrinsic polysilicon layer away from the tunnel oxide layer comprises:

[0014] A plurality of reflective layers with different refractive indices are sequentially deposited on a side of the intrinsic polysilicon layer away from the tunnel oxide layer.

[0015] In one embodiment, the refractive index is characterized by the refractive index and thickness of each of the reflective layers; the preset laser includes green light with a wavelength of 500nm~600nm picoseconds; multiple layers of the reflective layers with different refractive indices are sequentially deposited on the side of the intrinsic polysilicon layer away from the tunneling oxide layer, including:

[0016] A first reflective layer and a second reflective layer are sequentially deposited on a side of the intrinsic polysilicon layer away from the tunnel oxide layer; the refractive index of the first reflective layer is 2-6, and the thickness of the first reflective layer is 50nm-100nm; the refractive index of the second reflective layer is 2-2.3, and the thickness of the second reflective layer is 40nm-100nm.

[0017] In one embodiment, the material of the first reflective layer includes SiNx; the material of the second reflective layer includes SiOx.

[0018] In one embodiment, the reflective layer includes an aluminum film.

[0019] In one embodiment, the doping type includes boron doping; doping the exposed portion of the intrinsic polysilicon layer to form the first doped polysilicon layer includes:

[0020] Performing boron diffusion in the exposed portion of the intrinsic polysilicon layer to form the first doped polysilicon layer and a borosilicate glass layer located on a side of the first doped polysilicon layer away from the tunnel oxide layer;

[0021] The doping type further includes phosphorus doping; doping the remaining exposed intrinsic polysilicon layer to form the second doped polysilicon layer, comprising:

[0022] Phosphorus diffusion is performed in the remaining exposed intrinsic polysilicon layer to form the second doped polysilicon layer and a phosphosilicate glass layer located on a side of the second doped polysilicon layer away from the tunnel oxide layer.

[0023] In one embodiment, the passivation anti-reflection layer is formed on a side of the first doped polysilicon layer and the second doped polysilicon layer away from the tunnel oxide layer, comprising:

[0024] removing the borosilicate glass layer and the phosphosilicate glass layer;

[0025] The passivation anti-reflection layer is formed on a side of the first doped polysilicon layer and the second doped polysilicon layer away from the tunneling oxide layer.

[0026] In one of the embodiments, the thickness of the passivation anti-reflection layer is 40nm~80nm.

[0027] In a second aspect, the present application further provides a solar cell, which is prepared by the above-mentioned solar cell preparation method; the solar cell comprises:

[0028] substrate;

[0029] A tunneling oxide layer is disposed on the surface of the substrate;

[0030] A first doped polysilicon layer is disposed at a portion of a side of the tunnel oxide layer away from the substrate;

[0031] A second doped polysilicon layer is provided at the remaining position of the tunnel oxide layer on the side away from the substrate; the partial position and the remaining position constitute the entire position of the tunnel oxide layer on the side away from the substrate;

[0032] The passivation anti-reflection layer is disposed on a side of the first doped polysilicon layer and the second doped polysilicon layer away from the tunneling oxide layer.

[0033] In one embodiment, the solar cell comprises a TBC solar cell.

[0034] The above-mentioned solar cell preparation method and solar cell, the solar cell preparation method comprises depositing a tunneling oxide layer, an intrinsic polysilicon layer, a reflective layer and a mask layer on the surface of a substrate in sequence; removing part of the reflective layer and part of the mask layer to expose part of the intrinsic polysilicon layer; doping the exposed part of the intrinsic polysilicon layer to form a first doped polysilicon layer; removing the remaining reflective layer and the remaining mask layer to expose the remaining intrinsic polysilicon layer; the remaining reflective layer and part of the reflective layer constitute the entire reflective layer, the remaining mask layer and part of the mask layer constitute the entire mask layer, and the remaining intrinsic polysilicon layer and part of the intrinsic polysilicon layer constitute the entire intrinsic polysilicon layer; doping the exposed remaining intrinsic polysilicon layer to form a second doped polysilicon layer; the doping type of the second doped polysilicon layer is different from that of the first doped polysilicon layer; and preparing a passivation anti-reflection layer on the side of the first doped polysilicon layer and the second doped polysilicon layer away from the tunneling oxide layer. The solar cell preparation method of the present application deposits the reflective layer and the mask layer in sequence. When the mask layer is laser-opened, the structure of the reflective layer will not be affected, and no laser loss can be achieved. In addition, only the tunneling oxide layer and the intrinsic polysilicon layer need to be deposited once, and the reflective layer and the mask layer can be deposited simultaneously with the polysilicon layer, which greatly shortens the process time and reduces the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments of the present application or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 One of the schematic flow diagrams of a method for preparing a solar cell in an embodiment;

[0037] Figure 2 It is a schematic diagram of a process of preparing a passivation anti-reflection layer on a side of a first doped polysilicon layer and a second doped polysilicon layer away from a tunnel oxide layer in one embodiment;

[0038] Figure 3 The second schematic diagram is a flow chart of a method for preparing a solar cell in an embodiment;

[0039] Figure 4 FIG. 4 is a schematic diagram of the structure of a solar cell in one embodiment. DETAILED DESCRIPTION

[0040] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0041] In the description of the present application, it should be understood that, in addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present application, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0042] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0043] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0044] In the field of solar cell preparation, as the efficiency of traditional PERC (Passivated Emitter and Rear Cell), TOPCon (Tunnel Oxide Passivated Contact) and other solar cells gradually approaches the theoretical efficiency limit, technicians in this field have gradually focused on interdigitated back contact cells in pursuit of higher efficiency cells. Traditional back contact solar cells usually require two or three lasers, which cause more laser damage. In order to reduce laser damage as much as possible, people continue to explore laser processes, but the window of low damage processes is narrow, which limits the possibility of mass production.

[0045] Laser transfer and laser pulse deposition technologies require high preparation costs and are not suitable for large-scale mass production; high-concentration laser doping will also cause laser damage, and low-concentration laser doping will cause less laser damage, but the contact is poor; the combination of wet and annealing processes can reduce laser damage, but requires additional processes, which increases production costs. The solar cell preparation method of this application can avoid the damage caused by laser to other film layers, and can also shorten the process market and reduce production costs.

[0046] In one embodiment, see the attached Figure 1 , attached Figure 1 One of the flow charts of a method for preparing a solar cell in an embodiment of the present application is shown. The method for preparing a solar cell in this embodiment includes the following steps S101 to S106.

[0047] Step S101 , depositing a tunneling oxide layer, an intrinsic polysilicon layer, a reflective layer and a mask layer in sequence on the surface of a substrate.

[0048] The tunnel oxide layer, the intrinsic polysilicon layer, the reflective layer and the mask layer may be deposited by atomic layer deposition (ALD) and / or plasma enhanced chemical vapor deposition (PECVD).

[0049] The above-mentioned reflective layer is a high-reflective film layer capable of reflecting laser light, and the refractive index of the reflective layer can be set according to the adopted laser parameters. The above-mentioned mask layer can be an amorphous silicon film layer.

[0050] Step S102 , removing part of the reflective layer and part of the mask layer to expose part of the intrinsic polysilicon layer.

[0051] Among them, the methods of removing the reflective layer and the mask layer can be different. For example, part of the mask layer can be removed by laser, and part of the reflective layer can be removed by wet method. The part of the reflective layer and the part of the mask layer can refer to the reflective layer and the mask layer corresponding to the P region or N region of the solar cell.

[0052] Step S103 , doping the exposed portion of the intrinsic polysilicon layer to form a first doped polysilicon layer.

[0053] The first doped polysilicon layer may be a boron-doped polysilicon layer or a phosphorus-doped polysilicon layer. After removing part of the reflective layer and the mask layer, the first doped polysilicon layer is doped, so that a region corresponding to the dopant in the first doped polysilicon layer can be accurately formed at a part of the intrinsic polysilicon layer, such as an N region (the dopant is phosphorus) or a P region (the dopant is boron), while avoiding the dopant in the first doped polysilicon layer in the region other than the part.

[0054] Step S104, removing the remaining reflective layers and the remaining mask layers to expose the remaining intrinsic polysilicon layer; the remaining reflective layers and part of the reflective layers constitute the entire reflective layer, the remaining mask layers and part of the mask layers constitute the entire mask layer, and the remaining intrinsic polysilicon layers and part of the intrinsic polysilicon layers constitute the entire intrinsic polysilicon layer.

[0055] The remaining reflective layer and the remaining mask layer may be removed in different ways, for example, the remaining mask layer may be removed by laser, or by wet method, wherein the remaining reflective layer and the remaining mask layer may refer to the reflective layer and the mask layer corresponding to another area in the P area and the N area of ​​the solar cell except for the area corresponding to the partial reflective layer and the partial mask layer. For example, the partial reflective layer and the partial mask layer refer to the reflective layer and the mask layer corresponding to the P area of ​​the solar cell, and the remaining reflective layer and the remaining mask layer refer to the reflective layer and the mask layer corresponding to the N area of ​​the solar cell.

[0056] Step S105 , doping the remaining exposed intrinsic polysilicon layer to form a second doped polysilicon layer; the doping type of the second doped polysilicon layer is different from that of the first doped polysilicon layer.

[0057] The doping type of the second doped polysilicon layer may be one of phosphorus-doped and boron-doped except the doping type in the first doped polysilicon layer. For example, if the first doped polysilicon layer is a boron-doped polysilicon layer, the second doped polysilicon layer is a phosphorus-doped polysilicon layer.

[0058] When the remaining intrinsic polysilicon layer is doped, the glass layer formed when a portion of the intrinsic polysilicon layer is doped to form the first doped polysilicon layer can be used as a mask layer to isolate the dopant of the second doped polysilicon layer.

[0059] Step S106 , forming a passivation anti-reflection layer on a side of the first doped polysilicon layer and the second doped polysilicon layer away from the tunneling oxide layer.

[0060] Among them, the method for preparing the passivation anti-reflection layer can be plasma enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), thermal oxidation, magnetron sputtering deposition, electron beam evaporation deposition, etc., but not limited to this. It can be flexibly selected according to the type of passivation anti-reflection layer to be prepared or the characteristics of the above methods. For example, PECVD uses the plasma generated by glow discharge to activate the reaction gas and form a solid film on the surface of the substrate through chemical reaction. The PECVD method can be carried out at a lower temperature and is suitable for the deposition of temperature-sensitive materials. The deposition rate is relatively fast, so it can be used to deposit SiNx films. This film not only has a good passivation effect, but also has an anti-reflection function. It can be used as a passivation anti-reflection layer to effectively improve the photoelectric conversion efficiency of solar cells. ALD can accurately control the thickness of the film by alternately introducing different precursor gases into the reaction chamber and depositing only one atomic layer of material each time. It can be used to deposit Al 2 O 3 The film has a high fixed negative charge density and can effectively improve the field passivation effect of solar cells, reduce the surface recombination rate, and thus improve the cell efficiency.

[0061] The solar cell preparation method in this embodiment deposits the reflective layer and the mask layer in sequence. When the mask layer is laser-opened, the structure of the reflective layer is not affected, and no laser loss can be achieved. In addition, the tunneling oxide layer and the intrinsic polysilicon layer only need to be deposited once, and the high reflective layer and the mask layer can be deposited simultaneously with the polysilicon layer, which greatly shortens the process time and reduces the production cost.

[0062] In one embodiment, removing the portion and the remaining mask layer comprises removing the portion and the remaining mask layer by a preset laser; the preset laser corresponds to the refractive index of the reflective layer.

[0063] The width of the laser opening (i.e., removing part and the remaining mask layers) can be 540um~600μm, such as 540um, 550um, 560um, 570um, 580um, 590um, 600um, etc., but not limited thereto. However, it should be noted that the width of the opening of the part and the remaining mask layers should be consistent.

[0064] In this embodiment, a preset laser is used to remove all mask layers, and the preset laser corresponds to the refractive index of the reflective layer. The preset laser does not damage the reflective layer, and the reflective layer can also isolate the influence of the preset laser on the intrinsic polysilicon layer and the tunneling oxide layer, thereby being able to prepare a solar cell without laser loss.

[0065] In one embodiment, a reflective layer is deposited on a side of the intrinsic polysilicon layer away from the tunnel oxide layer, including sequentially depositing multiple reflective layers with different refractive indices on a side of the intrinsic polysilicon layer away from the tunnel oxide layer.

[0066] In this embodiment, multiple layers of reflective layers with different refractive indices are deposited in sequence on the side of the intrinsic polysilicon layer facing away from the tunneling oxidation pool, so that each reflective layer can play a role in reflecting and transmitting light, thereby having a higher comprehensive refractive index. At the same time, the isolation effect of the reflective layer is improved, which can ensure the preparation of solar cells without laser damage.

[0067] In one embodiment, the refractive index is characterized by the refractive index and thickness of each reflective layer; the preset laser includes green light with a wavelength of 500nm~600nm picoseconds; multiple layers of reflective layers with different refractive indices are deposited in sequence on the side of the intrinsic polysilicon layer away from the tunneling oxide layer, including: a first reflective layer and a second reflective layer are deposited in sequence on the side of the intrinsic polysilicon layer away from the tunneling oxide layer; the refractive index of the first reflective layer is 1.2~1.6, and the thickness of the first reflective layer is 50nm~100nm; the refractive index of the second reflective layer is 2~2.3, and the thickness of the second reflective layer is 40nm~100nm.

[0068] Exemplarily, the refractive index of the first reflective layer may be 1.2, 1.3, 1.4, 1.5, 1.6, etc., the thickness of the first reflective layer may be 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, 85nm, 90nm, 95nm, 100nm, etc., the refractive index of the second reflective layer may be 2, 2.1, 2.2, 2.3, etc., the thickness of the second reflective layer may be 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, 85nm, 90nm, 95nm, 100nm, etc., but is not limited to this.

[0069] In other embodiments, the preset laser may also be light of other wavelengths, such as violet light of 390nm~390nm, and the corresponding refractive index and thickness of the reflective layer may be measured based on experiments, and are not limited to the above examples.

[0070] In this embodiment, a first reflective layer and a second reflective layer are sequentially deposited on a side of the intrinsic polysilicon layer away from the tunnel oxide layer; the refractive index of the first reflective layer is 1.2-1.6, and the thickness of the first reflective layer is 50nm-100nm; the refractive index of the second reflective layer is 2-2.3, and the thickness of the second reflective layer is 40nm-100nm, which can improve the reflectivity of the reflective layer to 500nm-600nm picosecond green light.

[0071] In one embodiment, the material of the first reflective layer includes SiNx, and the material of the second reflective layer includes SiOx. In this embodiment, the first reflective layer is SiNx, and the second reflective layer is SiOx, which can ensure the reflectivity of the reflective layer to 500nm~600nm picosecond green light.

[0072] In one embodiment, the reflective layer comprises an aluminum thin film.

[0073] The thickness of the aluminum film may be 80 nm to 120 nm, such as 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, 105 nm, 110 nm, 115 nm, 120 nm, etc., but is not limited thereto. In this embodiment, an aluminum film may be deposited as a reflective layer. The broad-spectrum reflective capability of the aluminum film enables it to achieve efficient reflection in the entire visible spectrum, so that it can effectively reflect the laser and prevent the laser from damaging the film layers other than the mask layer.

[0074] In one embodiment, the doping type includes boron doping; doping the exposed portion of the intrinsic polysilicon layer to form a first doped polysilicon layer, including: performing boron diffusion in the exposed portion of the intrinsic polysilicon layer to form a first doped polysilicon layer and a borosilicate glass layer located on a side of the first doped polysilicon layer away from the tunnel oxide layer. The doping type also includes phosphorus doping; doping the exposed remaining intrinsic polysilicon layer to form a second doped polysilicon layer, including: performing phosphorus diffusion in the exposed remaining intrinsic polysilicon layer to form a second doped polysilicon layer and a phosphorus silicon glass layer located on a side of the second doped polysilicon layer away from the tunnel oxide layer.

[0075] In the present embodiment, boron diffusion is performed in the exposed portion of the intrinsic polysilicon layer to form a first doped polysilicon layer and a borosilicate glass layer located on the side of the first doped polysilicon layer away from the tunneling oxide layer. The borosilicate glass layer can be used as a mask layer for subsequent phosphorus diffusion in the remaining exposed intrinsic polysilicon layer, thereby preventing phosphorus from diffusing into the exposed portion of the intrinsic polysilicon layer.

[0076] In one embodiment, see the attached Figure 2 , attached Figure 2 A schematic diagram of the process of preparing a passivation anti-reflection layer on the side of the first doped polysilicon layer and the second doped polysilicon layer away from the tunneling oxide layer is shown. In this embodiment, the passivation anti-reflection layer is prepared on the side of the first doped polysilicon layer and the second doped polysilicon layer away from the tunneling oxide layer, including the following steps S201 to S202.

[0077] Step S201, removing the borosilicate glass layer and the phosphosilicate glass layer.

[0078] For example, the borosilicate glass layer and the phosphosilicate glass layer may be removed by a wet method, or may be removed by chain cleaning.

[0079] Step S202 , forming a passivation anti-reflection layer on a side of the first doped polysilicon layer and the second doped polysilicon layer away from the tunneling oxide layer.

[0080] In this embodiment, both the borosilicate glass layer and the phosphorus silicon glass layer will increase the recombination loss on the surface of the solar cell, reduce the minority carrier lifetime, thereby reducing the photocurrent, and will affect the firmness of the passivation anti-reflection layer, reducing the conversion efficiency of the cell. Therefore, after removing the borosilicate glass layer and the phosphorus silicon glass layer, a passivation anti-reflection layer is prepared on the side of the first doped polysilicon layer and the second doped polysilicon layer away from the tunneling oxide layer, which can improve the conversion efficiency of the solar cell, and the passivation anti-reflection layer can reduce the surface damage and oxidation reaction of the cell, extend the service life of the solar cell, and at the same time, the thickness and refractive index of the passivation anti-reflection layer can be optimized to achieve an anti-reflection effect in a specific wavelength range, thereby increasing the absorption and utilization of light by the solar cell. For example, the SiNx film has a good anti-reflection function, and the matching film thickness and refractive index can be formed by adjusting the reaction gas flow rate to reduce the refractive index to a minimum. In addition, the use of a multi-layer film stack structure with an anti-reflection effect as an anti-reflection layer, such as SiNx / SiNx and SiNx / SiO2 three-layer anti-reflection film layers, can further improve the electrical output characteristics of polycrystalline silicon solar cells.

[0081] In one embodiment, the thickness of the passivation anti-reflection layer is 40 nm to 80 nm. For example, the thickness of the passivation anti-reflection layer can be 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, etc., but is not limited thereto.

[0082] In this embodiment, the main function of the passivation anti-reflection layer is to reduce the reflection of incident light, increase light absorption and improve the short-circuit current of the battery. This effect is closely related to its thickness. Films of different thicknesses will produce different interference effects on light of different wavelengths. Setting the thickness of the passivation anti-reflection layer to 40nm~80nm can reduce the refractive index of sunlight to the minimum, ensuring the conversion efficiency of the solar cell.

[0083] In one embodiment, see the attached Figure 4 , attached Figure 4 The second schematic diagram shows a process flow of a method for preparing a solar cell in an embodiment of the present application. Figure 4 In (a), a tunnel oxide layer 320, an intrinsic polysilicon layer 330, a reflective layer 350 and a mask layer 360 are deposited on the back of a substrate 310 (such as a silicon substrate) by PECVD, wherein the reflective layer 350 can be a plurality of film layers with different refractive indices (such as a high-reflective green light stack composed of SiNx / SiOx, whose refractive index can be changed according to the film thickness and refractive index, and SiOx with a refractive index of 1.2-1.6 and SiNx with a refractive index of 2-2.3 can be selected, and the film thickness can be selected from 50-100 nm and 40-100 nm respectively), an aluminum film, etc., and the mask layer 360 can be an amorphous silicon film (the size of laser damage to the mask layer 360 does not need to be considered); Figure 4 In (b), 500 nm picosecond green light can be used to open the mask layer 360 in the p-region, and the p-region reflective layer 350 can be removed by wet process. The opening width is 540-600 μm, and the reflective layer 350 and the mask layer 360 are still left in the n-region. Figure 4 In FIG. (c), the intrinsic polysilicon layer 330 exposed in the P region is subjected to high-temperature boron diffusion, and a boron-doped polysilicon layer 331 and a BSG layer (borosilicate glass layer) 333 are formed in the P region. The surface BSG layer 333 also serves as a subsequent mask. Figure 4 In FIG. (d), the n-region mask layer 360 and the reflective layer 350 can be directly removed by a wet method, and then the intrinsic polysilicon layer 330 exposed in the n-region is phosphorus-doped to form a phosphorus-doped polysilicon layer 332 and a PSG layer (phosphorus silicon glass layer) 334; Figure 4 In FIG. 5( e ), the surface BSG layer 333 / PSG layer 334 can be removed by chain cleaning, and then a 40 nm to 80 nm passivation anti-reflection layer 340 can be deposited by conventional process.

[0084] In this embodiment, the reflective layer 350 on the intrinsic polysilicon layer 330 may not be affected by the laser, thereby avoiding damage to the underlying film when the outer mask layer 360 is opened by laser, thereby achieving a laser-free damage effect; and the solar cell preparation method in this embodiment only needs to deposit the tunneling oxide layer 320 and the intrinsic polysilicon layer 330 once, and the reflective layer 350 and the mask layer 360 can be deposited simultaneously with the intrinsic polysilicon layer 330, thereby shortening the process time.

[0085] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0086] Based on the same inventive concept, the embodiment of the present application also provides a solar cell prepared by the above-mentioned solar cell preparation method. The implementation solution provided by the solar cell to solve the problem is similar to the implementation solution recorded in the above-mentioned method, so the specific limitations in one or more solar cell embodiments provided below can refer to the limitations of the solar cell preparation method above, and will not be repeated here.

[0087] In one embodiment, the present application also provides a solar cell, see the attached Figure 4 , attached Figure 4 A schematic structural diagram of a solar cell in an embodiment of the present application is shown. The solar cell in this embodiment includes a substrate 310, a tunneling oxide layer 320, a first doped polysilicon layer 331, a second doped polysilicon layer 332 and a passivation anti-reflection layer 340. The tunneling oxide layer 320 is arranged on the surface of the substrate 310; the first doped polysilicon layer 331 is arranged at a partial position of a side of the tunneling oxide layer 320 away from the substrate 310; the second doped polysilicon layer 332 is arranged at the remaining position of the side of the tunneling oxide layer 320 away from the substrate 310; the partial position and the remaining position constitute the entire position of the side of the tunneling oxide layer 320 away from the substrate 310; the passivation anti-reflection layer 340 is arranged on the side of the first doped polysilicon layer 331 and the second doped polysilicon layer 333 away from the tunneling oxide layer 320.

[0088] In one embodiment, the solar cell comprises a TBC (Tunnel Back Contact) solar cell.

[0089] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0090] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for preparing a solar cell, characterized in that: The method comprises: Depositing a tunneling oxide layer, an intrinsic polysilicon layer, a reflective layer and a mask layer in sequence on the surface of the substrate; removing part of the reflective layer and part of the mask layer to expose part of the intrinsic polysilicon layer; doping the exposed portion of the intrinsic polysilicon layer to form a first doped polysilicon layer; removing the remaining reflective layer and the remaining mask layer to expose the remaining intrinsic polysilicon layer; the remaining reflective layer and part of the reflective layer constitute the entire reflective layer, the remaining mask layer and part of the mask layer constitute the entire mask layer, and the remaining intrinsic polysilicon layer and part of the intrinsic polysilicon layer constitute the entire intrinsic polysilicon layer; doping the remaining exposed intrinsic polysilicon layer to form a second doped polysilicon layer; the doping type of the second doped polysilicon layer is different from that of the first doped polysilicon layer; A passivation anti-reflection layer is formed on a side of the first doped polysilicon layer and the second doped polysilicon layer away from the tunnel oxide layer.

2. The method according to claim 1, characterized in that: Removing part and the rest of the mask layer, comprising: A portion and the rest of the mask layer are removed by a preset laser; the preset laser corresponds to the refractive index of the reflective layer.

3. The method according to claim 2, characterized in that Depositing the reflective layer on a side of the intrinsic polysilicon layer away from the tunnel oxide layer comprises: A plurality of reflective layers with different refractive indices are sequentially deposited on a side of the intrinsic polysilicon layer away from the tunnel oxide layer.

4. The method according to claim 3, characterized in that The refractive index is characterized by the refractive index and thickness of each of the reflective layers; the preset laser includes green light with a wavelength of 500nm~600nm picoseconds; multiple layers of the reflective layers with different refractive indices are sequentially deposited on the side of the intrinsic polysilicon layer away from the tunneling oxide layer, including: A first reflective layer and a second reflective layer are sequentially deposited on a side of the intrinsic polysilicon layer away from the tunnel oxide layer; the refractive index of the first reflective layer is 1.2-1.6, and the thickness of the first reflective layer is 50nm-100nm; the refractive index of the second reflective layer is 2-2.3, and the thickness of the second reflective layer is 40nm-100nm.

5. The method according to claim 4, characterized in that The material of the first reflective layer includes SiNx; the material of the second reflective layer includes SiOx.

6. The method according to claim 1, characterized in that The reflective layer includes an aluminum film.

7. The method according to claim 1, characterized in that The doping type includes boron doping; Doping the exposed portion of the intrinsic polysilicon layer to form the first doped polysilicon layer comprises: Performing boron diffusion in the exposed portion of the intrinsic polysilicon layer to form the first doped polysilicon layer and a borosilicate glass layer located on a side of the first doped polysilicon layer away from the tunnel oxide layer; The doping type further includes phosphorus doping; doping the remaining exposed intrinsic polysilicon layer to form the second doped polysilicon layer, comprising: Phosphorus diffusion is performed in the remaining exposed intrinsic polysilicon layer to form the second doped polysilicon layer and a phosphosilicate glass layer located on a side of the second doped polysilicon layer away from the tunnel oxide layer.

8. The method according to claim 7, characterized in that The passivation anti-reflection layer is formed on a side of the first doped polysilicon layer and the second doped polysilicon layer away from the tunnel oxide layer, comprising: removing the borosilicate glass layer and the phosphosilicate glass layer; The passivation anti-reflection layer is formed on a side of the first doped polysilicon layer and the second doped polysilicon layer away from the tunneling oxide layer.

9. The method according to claim 1, characterized in that: The thickness of the passivation anti-reflection layer is 40nm-80nm.

10. A solar cell, characterized in that: The solar cell is prepared by the method for preparing a solar cell according to any one of claims 1 to 9; the solar cell comprises: substrate; A tunneling oxide layer is provided on the surface of the substrate; A first doped polysilicon layer is disposed at a portion of a side of the tunnel oxide layer away from the substrate; A second doped polysilicon layer is provided at the remaining position of the tunnel oxide layer on the side away from the substrate; the partial position and the remaining position constitute the entire position of the tunnel oxide layer on the side away from the substrate; The passivation anti-reflection layer is disposed on a side of the first doped polysilicon layer and the second doped polysilicon layer away from the tunneling oxide layer.

11. The solar cell according to claim 10, characterized in that The solar cell comprises a TBC solar cell.

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