Solar cell manufacturing method and solar cell

Abstract

This application relates to a method for fabricating a solar cell and a solar cell, comprising sequentially depositing a tunneling oxide layer, an intrinsic polycrystalline silicon layer, a reflective layer, and a mask layer on a substrate surface; removing a portion of the reflective layer and a portion of the mask layer to expose a portion of the intrinsic polycrystalline silicon layer; doping the exposed portion of the intrinsic polycrystalline silicon layer to form a first doped polycrystalline silicon layer; removing the remaining reflective layer and the remaining mask layer to expose the remaining intrinsic polycrystalline silicon layer; doping the exposed remaining intrinsic polycrystalline silicon layer to form a second doped polycrystalline silicon layer; the doping type of the second doped polycrystalline silicon layer being different from that of the first doped polycrystalline silicon layer; and fabricating a passivation antireflection layer on the side of the first and second doped polycrystalline silicon layers facing away from the tunneling oxide layer. This application can achieve zero laser loss. Furthermore, only one deposition of the tunneling oxide layer and the intrinsic polycrystalline silicon layer is required, and the reflective layer and the mask layer can be deposited simultaneously with the polycrystalline silicon layer, greatly shortening the process time and reducing the production cost.

Description

Technical Field

[0001] This application relates to the field of solar cell fabrication technology, and in particular to a method for fabricating a solar cell and a solar cell. Background Technology

[0002] In the fabrication process of solar cells, lasers are inevitably used to open the film. However, lasers can 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] Therefore, it is necessary to provide a method for fabricating solar cells and a solar cell that can avoid laser damage in order to address the above-mentioned technical problems.

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

[0005] A tunneling oxide layer, an intrinsic polysilicon layer, a reflective layer, and a mask layer are sequentially deposited on the substrate surface;

[0006] Remove a portion of the reflective layer and a portion of the mask layer to expose a portion of the intrinsic polysilicon layer;

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

[0008] Remove the remaining reflective layers and the remaining mask layers to expose the remaining intrinsic polysilicon layers; the remaining reflective layers and a portion of the reflective layers constitute all the reflective layers, the remaining mask layers and a portion of the mask layers constitute all the mask layers, and the remaining intrinsic polysilicon layers and a portion of the intrinsic polysilicon layers constitute all the intrinsic polysilicon layers.

[0009] The remaining exposed intrinsic polysilicon layers are doped 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 antireflection layer is prepared on the side of the first doped polysilicon layer and the second doped polysilicon layer that is away from the tunneling oxide layer.

[0011] In one embodiment, removing part and the remainder of the mask layer includes:

[0012] A preset laser is used to remove part and the remainder of the mask layer; the preset laser corresponds to the refractive index of the reflective layer.

[0013] In one embodiment, the reflective layer is deposited on the side of the intrinsic polysilicon layer opposite to the tunneling oxide layer, including:

[0014] Multiple reflective layers with different refractive indices are sequentially deposited on the side of the intrinsic polycrystalline silicon layer opposite to the tunneling 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 500 nm to 600 nm picoseconds; multiple layers of the reflective layers with different refractive indices are sequentially deposited on the side of the intrinsic polycrystalline silicon layer facing away from the tunneling oxide layer, including:

[0016] A first reflective layer and a second reflective layer are sequentially deposited on the side of the intrinsic polycrystalline silicon layer opposite to the tunneling 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 comprises 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] Boron diffusion is performed on the exposed portion of the intrinsic polysilicon layer to form the first doped polysilicon layer and a borosilicate glass layer located on the side of the first doped polysilicon layer opposite to the tunneling oxide layer;

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

[0022] Phosphorus diffusion is performed on the remaining exposed intrinsic polysilicon layer to form the second doped polysilicon layer and a phosphorus-silicon glass layer located on the side of the second doped polysilicon layer opposite to the tunneling oxide layer.

[0023] In one embodiment, the passivation and antireflection layer is formed on the side of the first doped polysilicon layer and the second doped polysilicon layer facing away from the tunneling oxide layer, including:

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

[0025] The passivation antireflection layer is prepared on the side of the first doped polysilicon layer and the second doped polysilicon layer that is away from the tunneling oxide layer.

[0026] In one embodiment, the thickness of the passivation antireflection layer is 40 nm to 80 nm.

[0027] Secondly, this application also provides a solar cell, prepared by the above-described solar cell preparation method; the solar cell includes:

[0028] Substrate;

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

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

[0031] A second doped polysilicon layer is disposed at the remaining positions on the side of the tunneling oxide layer facing away from the substrate; the partial positions and the remaining positions constitute all positions of the tunneling oxide layer facing away from the substrate;

[0032] A passivation antireflection layer is disposed on the side of the first doped polysilicon layer and the second doped polysilicon layer opposite to the tunneling oxide layer.

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

[0034] The aforementioned solar cell fabrication method and solar cell, wherein the solar cell fabrication method includes sequentially depositing a tunneling oxide layer, an intrinsic polycrystalline silicon layer, a reflective layer, and a mask layer on a substrate surface; removing a portion of the reflective layer and a portion of the mask layer to expose a portion of the intrinsic polycrystalline silicon layer; doping the exposed portion of the intrinsic polycrystalline silicon layer to form a first doped polycrystalline silicon layer; removing the remaining reflective layer and the remaining mask layer to expose the remaining intrinsic polycrystalline silicon layer; the remaining reflective layer and a portion of the reflective layer constitute the entire reflective layer, the remaining mask layer and a portion of the mask layer constitute the entire mask layer, and the remaining intrinsic polycrystalline silicon layer and a portion of the intrinsic polycrystalline silicon layer constitute the entire intrinsic polycrystalline silicon layer; doping the exposed remaining intrinsic polycrystalline silicon layer to form a second doped polycrystalline silicon layer; the doping type of the second doped polycrystalline silicon layer being different from that of the first doped polycrystalline silicon layer; and fabricating a passivation antireflection layer on the side of the first doped polycrystalline silicon layer and the second doped polycrystalline silicon layer facing away from the tunneling oxide layer. The solar cell fabrication method of this application sequentially deposits a reflective layer and a mask layer. When the mask layer is laser-exposed, the structure of the reflective layer is not affected, achieving zero laser loss. Furthermore, only one deposition of the tunneling oxide layer and the intrinsic polycrystalline silicon layer is required, and the reflective layer and the mask layer can be deposited simultaneously with the polycrystalline silicon layer, greatly shortening the process time and reducing production costs. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is one of the schematic flowcharts of a solar cell fabrication method in one embodiment;

[0037] Figure 2 This is a schematic diagram of the process for preparing a passivation and antireflection layer on the side of the first doped polysilicon layer and the second doped polysilicon layer opposite to the tunneling oxide layer in one embodiment.

[0038] Figure 3 This is a second schematic flowchart of a solar cell fabrication method in one embodiment;

[0039] Figure 4 This is a schematic diagram of the structure of a solar cell in one embodiment. Detailed Implementation

[0040] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

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

[0042] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0043] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0044] In the field of solar cell fabrication, as the efficiency of traditional PERC (Passivated Emitter and Rear Cell) and TOPCon (Tunnel Oxide Passivated Contact) solar cells gradually approaches their theoretical efficiency limits, those skilled in the art are increasingly focusing on interdigitated back-contact solar cells in pursuit of higher efficiency. Traditional back-contact solar cells typically require two or three laser passes, resulting in significant laser damage. While researchers are continuously exploring laser processes to minimize laser damage, the narrow window for low-damage processes limits their mass production potential.

[0045] Laser transfer and laser pulse deposition technologies are costly and unsuitable for large-scale production. High-concentration laser doping can also cause laser damage, while low-concentration laser doping, although causing less laser damage, results in poor contact. Combining wet processing and annealing can reduce laser damage, but requires additional steps, increasing production costs. The solar cell fabrication method proposed in this application avoids laser damage to other film layers, shortens the process time, and reduces production costs.

[0046] In one embodiment, see Appendix Figure 1 , attached Figure 1 This paper shows one of the schematic flowcharts of a solar cell fabrication method according to an embodiment of the present application. The solar cell fabrication method in this embodiment includes the following steps S101 to S106.

[0047] Step S101: A tunneling oxide layer, an intrinsic polysilicon layer, a reflective layer, and a mask layer are sequentially deposited on the substrate surface.

[0048] Atomic layer deposition (ALD) and / or plasma enhanced chemical vapor deposition (PECVD) can be used to deposit the tunneling oxide layer, intrinsic polysilicon layer, reflective layer and mask layer.

[0049] The aforementioned reflective layer is a highly reflective film capable of reflecting laser light, and its refractive index can be set according to the laser parameters used. The aforementioned mask layer can be an amorphous silicon film.

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

[0051] The methods for removing the reflective layer and the mask layer can be different. For example, a portion of the mask layer can be removed by laser, and a portion of the reflective layer can be removed by wet methods. The portion of the reflective layer and the portion 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 can be a boron-doped polysilicon layer or a phosphorus-doped polysilicon layer. Doping the first doped polysilicon layer after removing part of the reflective layer and mask layer allows for the precise formation of regions corresponding to the dopants in the first doped polysilicon layer at specific locations within the intrinsic polysilicon layer, such as N-regions (phosphorus dopant) or P-regions (boron dopant), while preventing the regions outside these specific locations from being doped with the dopants from the first doped polysilicon layer.

[0054] Step S104: Remove the remaining reflective layers and the remaining mask layers to expose the remaining intrinsic polysilicon layers; the remaining reflective layers and the partial reflective layers constitute the entire reflective layer, the remaining mask layers and the partial mask layers constitute the entire mask layer, and the remaining intrinsic polysilicon layers and the partial intrinsic polysilicon layers constitute the entire intrinsic polysilicon layer.

[0055] The methods for removing the remaining reflective layers and remaining masking layers can differ. For example, the remaining masking layers can be removed using lasers, while the remaining reflective layers can be removed using wet methods. The remaining reflective layers and remaining masking layers can refer to the reflective layers and masking layers in another region of the P-region and N-region of the solar cell, excluding the regions corresponding to the partial reflective layers and partial masking layers. For instance, if the partial reflective layers and partial masking layers refer to the reflective layers and masking layers corresponding to the P-region of the solar cell, then the remaining reflective layers and remaining masking layers refer to the reflective layers and masking layers corresponding to the N-region of the solar cell.

[0056] Step S105: The remaining exposed intrinsic polysilicon layers are doped 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 can be either phosphorus doping or boron doping, except for the doping type in the first doped polysilicon layer. For example, if the first doped polysilicon layer is a boron-doped polysilicon layer, then the second doped polysilicon layer is a phosphorus-doped polysilicon layer.

[0058] When doping the remaining intrinsic polysilicon layers, the glass layer formed when doping a portion of the intrinsic polysilicon layers to form the first doped polysilicon layer can serve as a mask layer to isolate the dopants in the second doped polysilicon layer.

[0059] Step S106: A passivation antireflection layer is prepared on the side of the first doped polysilicon layer and the second doped polysilicon layer that is away from the tunneling oxide layer.

[0060] The methods for preparing passivation and antireflection layers can include plasma-enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), thermal oxidation, magnetron sputtering deposition, electron beam evaporation deposition, and so on. The specific method can be flexibly selected based on the type of passivation and antireflection layer to be prepared or the characteristics of the aforementioned methods. For example, PECVD utilizes plasma generated by glow discharge to activate reactive gases, forming a solid film on the substrate surface through a chemical reaction. PECVD can be performed at relatively low temperatures, making it suitable for depositing temperature-sensitive materials, and it has a relatively fast deposition rate. Therefore, it can be used to deposit SiNx films, which not only have good passivation effects but also antireflection functions, effectively improving the photoelectric conversion efficiency of solar cells. ALD, on the other hand, alternately introduces different precursor gases into the reaction chamber, depositing only one atomic layer of material at a time, allowing for precise control of the film thickness. It can be used to deposit Al2O3 films, which have a high fixed negative charge density, effectively improving the field passivation effect of solar cells, reducing the surface recombination rate, and thus improving cell efficiency.

[0061] In this embodiment, the solar cell fabrication method sequentially deposits a reflective layer and a mask layer. Laser-assisted opening of the mask layer does not affect the structure of the reflective layer, achieving zero laser loss. Furthermore, only one deposition of the tunneling oxide layer and the intrinsic polycrystalline silicon layer is required; the high-reflectivity layer and the mask layer can be deposited simultaneously with the polycrystalline silicon layer, significantly shortening the process time and reducing production costs.

[0062] In one embodiment, removing part and the remainder of the mask layer includes removing part and the remainder of the mask layer by means of a preset laser; the preset laser corresponds to the refractive index of the reflective layer.

[0063] The width of the laser ablation (i.e., the removal of part and the rest of the mask layer) can be 540um~600μm, such as 540um, 550um, 560um, 570um, 580um, 590um, 600um, etc., and is not limited to this. However, it should be noted that the ablation width of part and the rest of the mask layer should be consistent.

[0064] In this embodiment, a preset laser is used to remove all mask layers. 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 effect of the preset laser on the intrinsic polycrystalline silicon layer and the tunneling oxide layer, thereby enabling the fabrication of solar cells without laser loss.

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

[0066] In this embodiment, multiple reflective layers with different refractive indices are sequentially deposited on the side of the intrinsic polycrystalline silicon layer away from the tunneling oxide cell. This allows each reflective layer to both reflect and transmit light, resulting in a high overall refractive index. At the same time, it enhances the isolation effect of the reflective layers, ensuring the fabrication of laser-damaged solar cells.

[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 picosecond; multiple reflective layers with different refractive indices are sequentially deposited on the side of the intrinsic polycrystalline silicon layer away from the tunneling oxide layer, including: a first reflective layer and a second reflective layer are sequentially deposited on the side of the intrinsic polycrystalline silicon 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] For example, the refractive index of the first reflective layer can be 1.2, 1.3, 1.4, 1.5, 1.6, etc., and the thickness of the first reflective layer can be 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, 85nm, 90nm, 95nm, 100nm, etc., and the refractive index of the second reflective layer can be 2, 2.1, 2.2, 2.3, etc., and the thickness of the second reflective layer can be 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, 85nm, 90nm, 95nm, 100nm, etc., and is not limited thereto.

[0069] In other embodiments, the preset laser can also be light of other wavelengths, such as violet light of 390nm~390nm. The refractive index and thickness of the corresponding reflective layer can be determined experimentally 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 the side of the intrinsic polycrystalline silicon 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, which can improve the reflectivity of the reflective layer for green light of 500nm~600nm picosecond.

[0071] In one embodiment, the first reflective layer is made of SiNx, and the second reflective layer is made of SiOx. In this embodiment, setting the first reflective layer to SiNx and the second reflective layer to SiOx ensures the reflectivity of the reflective layer for green light in the 500nm~600nm picosecond range.

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

[0073] The thickness of the aluminum thin film can be 80nm~120nm, such as 80nm, 85nm, 90nm, 95nm, 100nm, 105nm, 110nm, 115nm, 120nm, etc., and is not limited to this. In this embodiment, an aluminum thin film can be deposited as a reflective layer. The broad-spectrum reflectivity of the aluminum thin film enables it to achieve efficient reflection across the entire visible spectrum, thus effectively reflecting laser light and preventing damage to the film layers other than the mask layer.

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

[0075] In this embodiment, boron diffusion is performed on 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 opposite to the tunneling oxide layer. The borosilicate glass layer can serve as a mask layer for subsequent phosphorus diffusion in the remaining exposed intrinsic polysilicon layers, thus preventing phosphorus from diffusing into the exposed portion of the intrinsic polysilicon layer.

[0076] In one embodiment, see Appendix Figure 2 , attached Figure 2 A schematic diagram of the process for preparing a passivation and antireflection 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, preparing a passivation and antireflection layer on the side of the first doped polysilicon layer and the second doped polysilicon layer away from the tunneling oxide layer includes the following steps S201 to S202.

[0077] Step S201: Remove the borosilicate glass layer and the phosphosilicate glass layer.

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

[0079] Step S202: A passivation antireflection layer is prepared on the side of the first doped polysilicon layer and the second doped polysilicon layer that is away from the tunneling oxide layer.

[0080] In this embodiment, both the borosilicate glass layer and the phosphosilicate glass layer increase recombination losses on the solar cell surface, reduce minority carrier lifetime, and thus reduce photocurrent. They also affect the robustness of the passivation antireflection layer, reducing the cell's conversion efficiency. Therefore, after removing the borosilicate glass layer and the phosphosilicate glass layer, a passivation antireflection layer is prepared on the side of the first and second doped polycrystalline silicon layers facing away from the tunneling oxide layer. This improves the solar cell's conversion efficiency, reduces surface damage and oxidation reactions, and extends the solar cell's lifespan. Furthermore, by optimizing the thickness and refractive index of the passivation antireflection layer, an antireflection effect within a specific wavelength range can be achieved, thereby increasing the solar cell's light absorption and utilization. For example, SiNx thin films have excellent antireflection properties; by adjusting the reactive gas flow rate to form a matching film thickness and refractive index, the refractive index can be minimized. In addition, using a multilayer film stack structure with antireflection effects as the antireflection layer, such as a SiNx / SiNx or SiNx / SiO2 three-layer antireflection film, can further improve the electrical output characteristics of the polycrystalline silicon solar cell.

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

[0082] In this embodiment, the main function of the passivation antireflection layer is to reduce the reflection of incident light, increase light absorption, and improve the short-circuit current of the cell. 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 antireflection layer to 40nm~80nm can minimize the refractive index of sunlight, ensuring the conversion efficiency of the solar cell.

[0083] In one embodiment, see Appendix Figure 4 , attached Figure 4 The second schematic flowchart of a solar cell fabrication method according to an embodiment of this application is shown. Figure 4 In Figure (a), a tunneling oxide layer 320, an intrinsic polycrystalline silicon layer 330, a reflective layer 350, and a mask layer 360 are deposited on the back side of a substrate 310 (which may be a silicon substrate) using PECVD. The reflective layer 350 may be a multilayer film with different refractive indices (such as a high-reflectivity stack for green light composed of SiNx / SiOx, whose refractive index can be changed according to the film thickness and refractive index, such as SiOx with a refractive index of 1.2~1.6 and SiNx with a refractive index of 2~2.3, and the film thickness can be selected as 50~100 nm and 40~100 nm, respectively), an aluminum thin film, etc. The mask layer 360 may be an amorphous silicon film (the size of laser damage does not need to be considered for the mask layer 360). Figure 4 In Figure (b), 500 nm picosecond green light can be selected 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 n region still retains the reflective layer 350 and the mask layer 360. Figure 4 In Figure (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 Figure (d), the n-region mask layer 360 and reflective layer 350 can be directly removed by wet process, and then the exposed intrinsic polysilicon layer 330 in the n-region is phosphorus-dipped to form a phosphorus-doped polysilicon layer 332 and a PSG layer (phosphosilicate glass layer) 334. Figure 4 In Figure (e), the surface BSG layer 333 / PSG layer 334 can be removed by chain cleaning, and then a 40nm~80nm passivation and antireflection layer 340 can be deposited using conventional processes.

[0084] In this embodiment, the reflective layer 350 on the intrinsic polycrystalline silicon layer 330 is unaffected by the laser, avoiding damage to the lower film when the outer mask layer 360 is opened by the laser, thus achieving a laser-free damage effect. Furthermore, the solar cell fabrication method in this embodiment only requires the deposition of the tunneling oxide layer 320 and the intrinsic polycrystalline silicon layer 330 once. The reflective layer 350 and the mask layer 360 can be deposited simultaneously with the intrinsic polycrystalline silicon layer 330, shortening the process time.

[0085] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0086] Based on the same inventive concept, this application also provides a solar cell fabricated using the solar cell fabrication method described above. The solution provided by this solar cell is similar to the solution described in the above method; therefore, the specific limitations of one or more solar cell embodiments provided below can be found in the limitations of the solar cell fabrication method described above, and will not be repeated here.

[0087] In one embodiment, this application also provides a solar cell, see appendix. Figure 4 , attached Figure 4 The diagram shows a schematic of a solar cell according to an embodiment of this application. The solar cell in this embodiment includes a substrate 310, a tunneling oxide layer 320, a first doped polycrystalline silicon layer 331, a second doped polycrystalline silicon layer 332, and a passivation antireflection layer 340. The tunneling oxide layer 320 is disposed on the surface of the substrate 310. The first doped polycrystalline silicon layer 331 is disposed at a portion of the side of the tunneling oxide layer 320 facing away from the substrate 310. The second doped polycrystalline silicon layer 332 is disposed at the remaining portion of the side of the tunneling oxide layer 320 facing away from the substrate 310. The portion and the remaining portion constitute the entire portion of the side of the tunneling oxide layer 320 facing away from the substrate 310. The passivation antireflection layer 340 is disposed on the side of the first doped polycrystalline silicon layer 331 and the second doped polycrystalline silicon layer 332 facing away from the tunneling oxide layer 320.

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

[0089] The technical features of the above embodiments can be combined in any way. For the sake of brevity, 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 embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for preparing a solar cell, characterized in that, The method includes: A tunneling oxide layer and an intrinsic polycrystalline silicon layer are sequentially deposited on the substrate surface; A reflective layer is deposited on the side of the intrinsic polycrystalline silicon layer opposite to the tunneling oxide layer; the reflective layer includes a first reflective layer and a second reflective layer deposited sequentially; the refractive index of the first reflective layer is 1.2~1.6; the refractive index of the second reflective layer is 2~2.3; A mask layer is deposited on the side of the reflective layer opposite to the intrinsic polysilicon layer; Remove a portion of the reflective layer and a portion of the mask layer to expose a portion of the intrinsic polysilicon layer; The exposed portion of the intrinsic polysilicon layer is doped to form a first doped polysilicon layer; Remove the remaining reflective layers and the remaining mask layers to expose the remaining intrinsic polysilicon layers; the remaining reflective layers and a portion of the reflective layers constitute all the reflective layers, the remaining mask layers and a portion of the mask layers constitute all the mask layers, and the remaining intrinsic polysilicon layers and a portion of the intrinsic polysilicon layers constitute all the intrinsic polysilicon layers. The remaining exposed intrinsic polysilicon layers are doped 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 and antireflection layer is prepared on the side of the first doped polysilicon layer and the second doped polysilicon layer that is away from the tunneling oxide layer; The removal of part and the remainder of the mask layer includes: A preset laser with a wavelength of 500nm~600nm is used to remove part and the rest of the mask layer; the preset laser corresponds to the refractive index of the reflective layer, and the refractive index of the reflective layer is characterized by the refractive index and thickness of the first reflective layer and the second reflective layer.

2. The method according to claim 1, characterized in that, The thickness of the first reflective layer is 50nm~100nm; the thickness of the second reflective layer is 40nm~100nm.

3. The method according to claim 1, characterized in that, The preset laser is a picosecond laser.

4. The method according to claim 3, characterized in that, The first reflective layer is made of SiNx; the second reflective layer is made of SiOx.

5. 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 includes: Boron diffusion is performed on the exposed portion of the intrinsic polysilicon layer to form the first doped polysilicon layer and a borosilicate glass layer located on the side of the first doped polysilicon layer opposite to the tunneling oxide layer; The doping type further includes phosphorus doping; doping the remaining exposed intrinsic polysilicon layers to form the second doped polysilicon layer includes: Phosphorus diffusion is performed on the remaining exposed intrinsic polysilicon layer to form the second doped polysilicon layer and a phosphorus-silicon glass layer located on the side of the second doped polysilicon layer opposite to the tunneling oxide layer.

6. The method according to claim 5, characterized in that, The passivation and antireflection layer is formed on the side of the first doped polysilicon layer and the second doped polysilicon layer opposite to the tunneling oxide layer, including: Remove the borosilicate glass layer and the phosphosilicate glass layer; The passivation antireflection layer is prepared on the side of the first doped polysilicon layer and the second doped polysilicon layer that is away from the tunneling oxide layer.

7. The method according to claim 1, characterized in that, The thickness of the passivation antireflection layer is 40nm~80nm.

8. A solar cell, characterized in that, The solar cell is prepared by the solar cell preparation method according to any one of claims 1 to 7; the solar cell comprises: Substrate; A tunneling oxide layer is disposed on the surface of the substrate; A first doped polysilicon layer is disposed on a portion of the side of the tunneling oxide layer facing away from the substrate; A second doped polysilicon layer is disposed at the remaining positions on the side of the tunneling oxide layer facing away from the substrate; the partial positions and the remaining positions constitute all positions of the tunneling oxide layer facing away from the substrate; A passivation antireflection layer is disposed on the side of the first doped polysilicon layer and the second doped polysilicon layer opposite to the tunneling oxide layer.

9. The solar cell according to claim 8, characterized in that, The solar cells include TBC solar cells.

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