Photovoltaic modules, solar cells and their manufacturing methods

Abstract

This application discloses a photovoltaic module, a solar cell, and a method for fabricating the same. The solar cell includes a substrate having a first surface and a second surface disposed opposite to each other. A first doped region is located on the first surface. In the first doped region, the doping concentration of non-active elements is 1E19 to 1E22, and the doping concentration of active elements is 1E17 to 8E18. In the first doped region, the doping concentration of the active elements first increases and then decreases in the direction from the first surface to the substrate. The difference between the maximum doping concentration of the active elements and the doping concentration of the active elements at the first surface is 1E18 to 7E18.

Description

Technical Field

[0001] This application relates to the photovoltaic field, specifically to a photovoltaic module, a solar cell, and a method for preparing the same. Background Technology

[0002] Improving photoelectric conversion efficiency and reducing production costs are the enduring goals of mass-producing solar cells, aiming to lower the levelized cost of electricity (LCOE) for photovoltaic power generation. Currently, tunneling passivation structures are widely used in the solar cell field. However, these structures require high doping concentrations of doping elements to effectively passivate the substrate and ensure cell efficiency. Furthermore, the fabrication of existing tunneling passivation layers involves multiple processes: the tunneling layer itself, the passivation layer, and subsequent doping preparation. This multi-step process inevitably leads to excessively long fabrication times. Additionally, the various steps require mutual matching, resulting in a narrow process window, high fabrication difficulty, and uncontrollable yield, especially since it is incompatible with the novel LECO electrode fabrication process. Summary of the Invention

[0003] To address the problems existing in the prior art, this application provides a solar cell with low doping element content in its first doped region and good cell performance.

[0004] Specifically, this application relates to the following aspects:

[0005] This application provides a solar cell, including a substrate having a first surface and a second surface disposed opposite to each other. A first doped region is located on the first surface. Within the first doped region, the doping concentration of non-active elements is 1E19 to 1E22, and the doping concentration of active elements is 1E17 to 8E18. Within the first doped region, from near the first surface into the substrate, the doping concentration of the active elements first increases and then decreases. The difference between the maximum doping concentration of the active elements and the doping concentration of the active elements at the first surface is 1E18 to 7E18. Compared with the prior art, the solar cell of this application, while maintaining the same electrical performance as prior art cells, reduces the doping concentration of both active and non-active elements. Lower doping concentrations result in less recombination of the doped elements, better passivation effect, and a higher open-circuit voltage. Conventional cells in the prior art require high doping concentrations to match conventional screen printing in order to form good metal-semiconductor contacts, thereby collecting the current generated by the substrate. However, this application uses the LECO process, which can achieve good contact (metal-semiconductor contact) between the first electrode and the first doped region on the first doped region with a lower doping concentration. Therefore, the solar cell of this application is matched with the corresponding LECO process, which takes into account both low surface doping concentration samples with low recombination and good contact, thereby increasing the open circuit voltage of the cell while maintaining the same or even slightly improved fill factor.

[0006] In some embodiments, a first electrode is disposed on the surface of the first doped region away from the substrate, and a portion of the first electrode extends into the first doped region; the contact resistivity between the first electrode and the first doped region is 0.1–3 mΩ / cm. 2 Because the battery manufacturing process employs the LECO process, the contact resistivity between the first electrode and the first doped region is reduced compared to existing technologies. Consequently, without altering the battery performance, the doping concentrations of both active and non-active elements within the first doped region are also reduced.

[0007] In some embodiments, the first surface corresponding to the first doped region has a first tower-like texture structure; the first tower-like texture structure includes a plurality of first towers; under a 20x microscope, within an area of ​​650μm × 650μm, the number of quadrilaterals projected onto the substrate by the first towers is 1-10; and / or the height of the first towers is 0-0.3μm, excluding 0; and / or the sheet resistance of the first doped region is 200ohm-500ohm, and within a depth range of 0.1-0.4μm from the first surface, the first... The doped region has the maximum doping concentration of the active element; the junction depth of the first doped region is 1-1.5 μm; if the first base is too high or the number of first bases is too large, the roughness of the first surface will increase, the surface will be uneven, and the quality of the film layer subsequently stacked on it will be affected; if the first base is too small, the density of the first base will increase, which will affect the quality of the film layer subsequently stacked on it. At the same time, a suitable base size reduces the doping concentration of the active element and the doping concentration of the non-active element in the first doped region, thus better matching the corresponding LECO process.

[0008] The difference between the maximum doping concentration of the active element and the depth of the junction from the first surface is 0.9-1.3 μm. The closer the maximum doping concentration of the active element is to the first surface, the closer the inactive elements are to the first surface. A higher doping concentration of inactive elements on the first surface makes it easier to form strong recombination regions, which are difficult to remove, leading to a decrease in battery performance. In this application, the location of the maximum doping concentration of the active element achieves optimal passivation and contact effects.

[0009] In some embodiments, the first surface corresponding to the first doped region has a first pyramidal texture structure with a height of 0.5-3 μm. During battery fabrication, at this height, the diffusion of dopant elements has minimal impact on the first pyramidal texture structure during the fabrication of the first doped region. The first pyramidal texture structure balances reflectivity and provides a smaller tip area and a smaller high recombination area in the subsequent contact fabrication of the first electrode. Simultaneously, the appropriate pyramid size correspondingly reduces the doping concentration of both active and non-active elements within the first doped region, thus better matching the corresponding LECO process. Within a depth range of 0.05-0.3 μm from the first surface, the first doped region has the maximum doping concentration of active elements; the junction depth of the first doped region is 0.8-1.2 μm. The maximum doping concentration of active elements plays a major role in the subsequent formation of the contact between the first electrode and the first doped region. Within the depth range of the location of the maximum doping concentration of active elements, the first electrode and the first doped region achieve optimal contact resistivity, which is beneficial for the collection of photocurrent.

[0010] The difference between the depth of the maximum doping concentration of the active element from the first surface and the depth of the junction from the first surface is 0.5-0.8 μm. The regions from the location of the maximum doping concentration of the active element to the first surface and from the location of the maximum doping concentration of the active element to the substrate are the two main regions involved in conductivity. However, the region from the location of the maximum doping concentration of the active element to the first surface has the greatest recombination effect. Therefore, adjusting the ratio of the depth from the location of the maximum doping concentration of the active element to the first surface to the entire junction depth can minimize the impact of surface recombination while ensuring contact.

[0011] In some embodiments, a first passivation layer and a first electrode are disposed on the side of the first doped region away from the second surface. The first passivation layer covers the first doped region. The first electrode includes a current collector electrode extending along a second direction and arranged along a first direction. A portion of the current collector electrode passes through the first passivation layer along the second direction and contacts the first doped region. The second direction intersects the first direction.

[0012] In some embodiments, the first electrode further includes an interconnect portion electrically connected to the current collector electrode, the interconnect portion being arranged along a second direction; the interconnect portion is located on the surface of the first passivation layer opposite to the first doped region, and the current collector electrode includes a current collector portion adjacent to the interface between the interconnect portion and the current collector electrode along the second direction, and is located on the surface of the first passivation layer opposite to the first doped region or within the first passivation layer; along the second direction, the size of the current collector portion is less than or equal to one-third of the spacing between adjacent interconnect portions. This interconnect portion can prevent a large number of first electrodes at the intersection from damaging the contact between the first passivation layer and the underlying first doped region, causing severe metal recombination.

[0013] In some embodiments, the battery further includes a second doped region located on the first surface, the first doped region and the second doped region being arranged alternately, the second doped region having the opposite conductivity type to the first doped region; the first surface corresponding to the first doped region has a first tower-like texture structure; the first surface corresponding to the second doped region has a second tower-like texture structure; the second tower-like texture structure includes a plurality of second towers;

[0014] The one-dimensional dimension of the second tower base is greater than or equal to the one-dimensional dimension of the first tower base;

[0015] The one-dimensional dimension of the second tower base is the dimension of the side surface of the second tower base away from the base;

[0016] The height of the second tower base is less than or equal to the height of the first tower base.

[0017] The films formed on the surfaces of the first and second substrates are different, thus requiring different morphologies for the substrates. For the second doped region, the size of the second substrate needs to be as small as possible to ensure that the tunneling layer prepared on this morphology has higher quality. However, for the first doped region, the first substrate with certain undulations can increase the area of ​​the first doped region. At the same time, the morphology of the first substrate will affect the morphology of the second substrate. The first substrate is prepared first, and the second substrate corresponding to the second doped region is prepared on the basis of the first substrate.

[0018] In some embodiments, the battery further includes a second doped region located on the first surface, with the first and second doped regions arranged alternately; the second doped region has the opposite conductivity type to the first doped region; the first surface corresponding to the first doped region has a first pyramidal texture structure, and the first surface corresponding to the second doped region has a second pyramidal texture structure; the second pyramidal texture structure includes a plurality of second pyramidal bases.

[0019] The one-dimensional dimension of the second tower base is smaller than the one-dimensional dimension of the base of the first pyramid-shaped textured structure; the one-dimensional dimension of the second tower base is the dimension of the side surface of the second tower base away from the base;

[0020] Under this matching, the diffusion process of dopant elements has minimal impact on the first pyramidal texture structure during the preparation of the first doped region. The first pyramidal texture structure can balance reflectivity and provide a smaller tip area and a smaller high recombination area in the subsequent preparation of the first electrode contact. At the same time, the appropriate pyramid size reduces the doping concentration of active elements and non-active elements in the first doped region, thus better matching the corresponding LECO process. The second doped region adopts a second pyramid base structure. If the second pyramid base is too high, the roughness of the first surface corresponding to the second doped region will increase, resulting in an uneven surface and affecting the quality of the film layer subsequently stacked on top of it. If the second pyramid base is too small, the density of the second pyramid base will increase, which will also affect the quality of the film layer subsequently stacked on top of it.

[0021] The height of the second base is less than the height of the first pyramid-shaped texture structure, which is beneficial for preparing gap regions that are easy to passivate.

[0022] In some embodiments, the battery further includes a second doped region and a first passivation layer. The second doped region is located on the first surface, and the first and second doped regions are arranged alternately. The second doped region has the opposite conductivity type to the first doped region. A gap region is formed between the first and second doped regions. The roughness of the first surface corresponding to the gap region is 0-1 μm. The first passivation layer covers the gap region. The passivation of the first surface of the gap region is achieved through the combined action of field passivation and hydrogen passivation of the first passivation layer (alumina and silicon nitride). However, excessive roughness can lead to poor film quality of the first passivation layer.

[0023] In some embodiments, the battery further includes a second doped region and a first passivation layer, the second doped region being located on the first surface, the first doped region and the second doped region being arranged alternately; the second doped region having the opposite conductivity type to the first doped region; a gap region being formed between the first doped region and the second doped region; and the first passivation layer covering the gap region.

[0024] The first surface corresponding to the first doped region has a first pyramidal texture structure; the height difference between the first surface corresponding to the gap region and the first surface corresponding to the first doped region is 0.5-6 μm; or the first surface corresponding to the first doped region has a first pyramidal texture structure; the height difference between the first surface corresponding to the gap region and the first surface corresponding to the first doped region is 0.5-8 μm. The passivation of the first surface of the gap region is achieved through the combined action of field passivation and hydrogen passivation of the first passivation layer (alumina and silicon nitride). The first surface of the gap region is lower than the first surface of the first doped region, thus forming a pit in the gap region. This increases the contact area between the first surface of the gap region and alumina and hydrogen, suspending the passivated surface and thus strengthening the passivation of the first surface. When the pit is too deep, the alumina in that region will be relatively thin, resulting in a poorer alumina passivation effect. When the pit is too shallow, the original first doped region within the pit cannot be completely removed during battery fabrication, and the residue will form a high-strength recombination center with the new diffusion layer during the fabrication of the second doped region.

[0025] In some embodiments, both the active and inactive elements of the first doped region are Group 3 elements. The battery further includes a second doped region located on the first surface, with the first and second doped regions arranged alternately. The second doped region includes a tunneling layer and a second silicon-doped layer. One side of the tunneling layer is stacked on the first surface of the substrate, and the other side is stacked with the second silicon-doped layer. The roughness of the first surface corresponding to the second doped region is less than or equal to 0.5 μm. Low roughness facilitates the growth of a denser tunneling layer, resulting in superior chemical passivation and transport effects.

[0026] In some embodiments, the battery further includes a second doped region located on the second surface. The second surface has a third pyramidal texture structure. The second doped region includes a tunneling layer and a second silicon-containing doped layer stacked sequentially. The first doped region has the opposite conductivity type to the second doped region. The first pyramidal texture structure can balance reflectivity and provide a smaller tip area and a smaller high recombination area in the subsequent contact process of the first electrode. At the same time, the appropriate pyramid size reduces the doping concentration of active elements and non-active elements in the first doped region, thus better matching the corresponding LECO process. The second surface has a third pyramidal texture structure. If the third pyramid is too high, the roughness of the first surface corresponding to the second doped region will increase, resulting in an uneven surface and affecting the quality of the film layer subsequently stacked on top of it. If the third pyramid is too small, the density of the third pyramid will increase, which will affect the quality of the film layer subsequently stacked on top of it.

[0027] This application also provides a method for preparing a solar cell, comprising the following steps:

[0028] A substrate is provided; the substrate has a first surface and a second surface disposed opposite to each other;

[0029] A dopant element enters the substrate from the first surface of the substrate, thereby forming a first doped region;

[0030] In the first doped region, the doping concentration of the non-active element is 1E19 to 1E22, and the doping concentration of the active element is 1E17 to 8E18. In the first doped region, the doping concentration of the active element first increases and then decreases in the direction from near the first surface to the substrate. The difference between the maximum doping concentration of the active element and the doping concentration of the active element at the first surface is 1E18 to 7E18.

[0031] In some embodiments, after forming the first doped region, a first electrode is formed on the first doped region, and the first electrode extends at least partially into the first doped region.

[0032] In some embodiments, forming the first electrode includes the following steps:

[0033] Forming the first electrode precursor;

[0034] The first electrode precursor and the first doped region are processed using the LECO process.

[0035] In some embodiments, when the first surface corresponding to the first doped region has a first pyramidal texture structure, the diameter of the laser spot used in the LECO process is less than or equal to the distance between the highest points of adjacent pyramidal apexes in the first pyramidal texture structure; or

[0036] When the first surface corresponding to the first doped region has a first tower-like texture structure, and the first tower-like texture structure includes multiple first towers, the diameter of the laser spot used in the LECO process is less than or equal to the distance between the geometric centers of adjacent first towers in the polished surface.

[0037] In some embodiments, the prepared solar cell is the aforementioned solar cell.

[0038] This application also provides a photovoltaic module, including the aforementioned solar cell, or a solar cell prepared by the aforementioned preparation method.

[0039] The solar cell provided in this application employs LECO technology during its fabrication process, which reduces the contact resistivity between the first electrode and the first doped region compared to existing technologies. While maintaining cell performance, this also correspondingly reduces the doping concentration of both active and non-active elements within the first doped region. Consequently, the solar cell of this application achieves both low surface doping concentration due to low recombination in the first doped region and good contact between the first doped region and the first electrode, resulting in an increased open-circuit voltage and a similar or even slightly improved fill factor. Attached Figure Description

[0040] The accompanying drawings are provided to better understand this application and do not constitute an undue limitation thereof. Wherein:

[0041] Figure 1 This is a structural diagram of the solar cell provided in this application.

[0042] Figure 2 A partial structural diagram of the solar cell provided in this application.

[0043] Figure 3 A partial structural diagram of the solar cell provided in this application.

[0044] Explanation of reference numerals in the attached figures

[0045] 1-Silicon substrate, 2-First doped region, 3-First electrode, 4-Second silicon doped layer, 5-Tunneling layer, 6-Second electrode, 7-Passivation layer, 8-Main electrode, 9-Collector electrode, 10-Interconnection. Detailed Implementation

[0046] The following description provides exemplary embodiments of this application, including various details to aid understanding, and should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this application. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0047] This application provides a solar cell, including a substrate having a first surface and a second surface disposed opposite to each other. A first doped region 2 is located on the first surface. In the first doped region 2, the doping concentration of non-active elements is 1E19 to 1E22, and the doping concentration of active elements is 1E17 to 8E18. In the first doped region 2, from the direction near the first surface to the substrate, the doping concentration of active elements first increases and then decreases. The difference between the maximum doping concentration of active elements and the doping concentration of active elements at the first surface is 1E18 to 7E18. The lower the doping concentration of the active element and the lower the doping concentration of the non-active element, the smaller the recombination of the doped elements, the better the passivation effect of the cell, and the higher the open-circuit voltage of the cell. Conventional cells require high doping concentration to match conventional screen printing in order to form good metal-semiconductor contact, thereby collecting the current generated by the substrate. However, this application uses the LECO process, which can achieve better contact (metal-semiconductor contact) between the first electrode and the first doped region on a substrate with a lower doping concentration. Therefore, the solar cell of this application is matched with the corresponding LECO process, which takes into account both the low recombination and low surface doping concentration sample and achieves good contact, thereby increasing the open-circuit voltage of the cell while maintaining the same or even slightly improved fill factor.

[0048] In this paper, the first surface of the substrate is the backlight surface, and the second surface is the light-facing surface.

[0049] The first doped region 2 is located within the substrate and is a region close to the first surface (including the first surface), that is, the first doped region 2 is a region extending from the first surface into the substrate to a certain depth.

[0050] In some embodiments, the doping concentration of the non-active element in the first doped region 2 can be 5E19 to 5E21.

[0051] In some embodiments, the doping concentration of non-active elements in the first doped region 2 can be 5E19 to 1E21.

[0052] In some embodiments, the doping concentration of the active element in the first doped region 2 is 1E17 to 7E18.

[0053] In some embodiments, the doping concentration of the active element in the first doped region 2 is 1E17 to 5E18.

[0054] In some embodiments, the doping concentration of the active element in the first doped region 2 is 1E17 to 3E18.

[0055] In some implementations, the difference between the maximum doping concentration of the active element and the doping concentration of the active element at the first surface is 1E18 to 3E18.

[0056] In some implementations, the difference between the maximum doping concentration of the active element and the doping concentration of the active element at the first surface is 1E18 to 5E18.

[0057] Specifically, in the first doped region 2, the doping concentration of the non-active element can be 1E19, 2E19, 3E19, 4E19, 5E19, 6E19, 7E19, 8E19, 9E19, 1E20, 2E20, 3E20, 4E20, 5E20, 6E20, 7E20, 8E20, 9E20, 1E21, 2E21, 3E21, 4E21, 5E21, 6E21, 7E21, 8E21, 9E21, or 1E22.

[0058] Specifically, in the first doped region 2, the doping concentration of the active element is 1E17, 2E17, 3E17, 4E17, 5E17, 6E17, 7E17, 8E17, 9E17, 1E18, 2E18, 3E18, 4E18, 5E18, 6E18, 7E18, or 8E18.

[0059] Specifically, in the first doped region 2, the difference between the maximum doping concentration of the active element and the doping concentration of the active element at the first surface can be 1E18, 2E18, 3E18, 4E18, 5E18, 6E18 or 7E18.

[0060] Those skilled in the art will understand that the doping concentration of the non-active element / active element in the first doped region 2 can refer to the concentration of the non-active element / active element at any site on the surface or within the first doped region 2. Alternatively, it can be the average of the doping concentrations at multiple sites or the average of the doping concentrations of the non-active element / active element in the first doped region 2. Those skilled in the art can select any of the aforementioned sites for detection based on the detection conditions and the instruments used, or they can detect multiple sites and calculate the average of these sites as the concentration of the non-active element / active element. In one specific embodiment, the concentration of the non-active element / active element refers to the average value detected over the thickness of the non-active element / active element. For example, the SIMS method can be used to detect the concentration of the non-active element / active element in the first doped region 2 along a thickness direction, and the average value along that thickness direction can be calculated.

[0061] In this paper, the doping concentration of the non-active element in the first doping region refers to the concentration value detected at any random site in the first doping region, and the doping concentration of the non-active element is 1E19 to 1E22, which means that any detected concentration is within the range of 1E19 to 1E22.

[0062] In this paper, the doping concentration of the active element in the first doped region refers to the concentration value detected at any random site in the first doped region, and the doping concentration of the active element 1E17~8E18 means that any detected concentration is in the range of 1E17~8E18.

[0063] In this paper, the active elements are generally tested using the ECV (Electronic Capacitance Voltage Method). The inactive dopants are tested using both ECV and SIMS (Secondary Ion Mass Spectrometry). ECV can determine the concentration of dopants involved in conduction. Compared to SIMS, which measures the dopant composition, SIMS, when the dopant is known to be phosphorus or boron, determines the total concentration of that element (A). ECV, on the other hand, can determine the concentration of the dopant involved in conduction (B, i.e., the concentration of the active element), and the concentration of inactive impurities (C) is AB.

[0064] In this paper, active elements are dopants in an activated state, and inactive elements are dopants in an inactive state. Dopants have two functions: first, they participate in conduction (the function of active elements); second, they recombine electrons or holes (the function of inactive elements). Inactive elements are recombination centers, i.e., they capture charge carriers and hinder their movement. Therefore, the higher the doping concentration of inactive elements, the more charge carriers are captured, and the greater the decline in battery performance, mainly reflected in the open-circuit voltage. That is, as the concentration of inactive dopants increases, the open-circuit voltage of the battery will continue to decrease. Therefore, while satisfying its conductivity, the lower the doping concentration of both active and inactive elements, the better the passivation effect of the battery, and the higher the corresponding open-circuit voltage.

[0065] like Figure 2 A first electrode 3 is disposed on the surface of the first doped region 2 away from the substrate, and a portion of the first electrode 3 extends into the first doped region 2.

[0066] The contact resistivity between the first electrode 3 and the first doped region 2 is 0.1–5 mΩ / cm. 2 In some embodiments, the contact resistivity is 0.1–3 mΩ / cm. 2 In some embodiments, the contact resistivity is 0.1–1.5 mΩ / cm. 2 .

[0067] Specifically, the contact resistivity between the first electrode 3 and the first doped region 2 can be 0.1 mΩ / cm. 2 0.2mΩ / cm 2 0.3mΩ / cm 2 0.4mΩ / cm 2、0.5mΩ / cm 2 、1mΩ / cm 2 、1.1mΩ / cm 2 、1.2mΩ / cm 2 、.3mΩ / cm 2 、1.4mΩ / cm 2 、1.5mΩ / cm 2 、1.6mΩ / cm 2 、1.7mΩ / cm 2 、1.8mΩ / cm 2 、1.9mΩ / cm 2 、2mΩ / cm 2 、2.1mΩ / cm 2 、2.2mΩ / cm 2 、2.3mΩ / cm 2 、2.4mΩ / cm 2 、2.5mΩ / cm 2 、2.6mΩ / cm 2 、2.7mΩ / cm 2 、2.8mΩ / cm 2 、2.9mΩ / cm 2 、3mΩ / cm 2 、3.1mΩ / cm 2 、3.2mΩ / cm 2 、3.3mΩ / cm 2 、3.4mΩ / cm 2 、3.5mΩ / cm 2 、3.6mΩ / cm 2 、3.7mΩ / cm 2 、3.8mΩ / cm 2 、3.9mΩ / cm 2 、4mΩ / cm 2 、4.1mΩ / cm 2 、4.2mΩ / cm 2 、4.3mΩ / cm 2 、4.4mΩ / cm 2 、4.5mΩ / cm 2 、4.6mΩ / cm 2 、4.7mΩ / cm 2 、4.8mΩ / cm 2 、4.9mΩ / cm 2 、5mΩ / cm 2 。

[0068] In this paper, the TLM (Transfer Length Method) test is used to test the contact resistivity between the first electrode 3 and the first doped region 2. The test principle is based on TLM technology, which involves fabricating a series of electrodes of different lengths on a material and then measuring the resistance between the electrodes to infer the material's conductivity. The TLM tester works by utilizing the influence of resistance on current transmission between electrodes; by measuring the resistance value, the material's conductivity can be obtained. When current travels between electrodes, it is affected by both the contact resistance of the electrodes and the bulk resistance of the material itself. The TLM tester can separate these two influences by measuring the resistance value between the electrodes.

[0069] Because the battery manufacturing process employs LECO technology, the contact resistivity between the first electrode 3 and the first doped region 2 is reduced compared to existing technologies. Consequently, without altering the battery performance, the doping concentration of both active and non-active elements in the first doped region 2 is also reduced.

[0070] In this application, the ratio of the contact area between the first electrode 3 and the first doped region 2 to the projected area of ​​the first doped region 2 on the substrate is (0.5 to 2):1, for example, it can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, etc.

[0071] This ensures contact between the first electrode 3 and the first doped region 2, thereby reducing the contact resistivity and giving the battery good metal-semiconductor contact, which is beneficial for current collection.

[0072] The projected area of ​​the first doped region 2 on the substrate can be calculated by measuring its one-dimensional dimension using a microscope. The one-dimensional dimension can be the length and the width.

[0073] The contact area between the first electrode 3 and the first doped region 2 is the sum of the effective contact area and the ineffective contact area. The first electrode can be removed by acid etching solution, and then the contact area (i.e. the total area) between the first electrode 3 and the first doped region 2 can be calculated by 3D scanning. The surface area of ​​the irregular area after removing the first electrode is the ineffective contact area, and the effective contact area is the total area minus the ineffective contact area.

[0074] The ratio of the effective contact area between the first electrode 3 and the first doped region 2 to the total contact area between the first electrode 3 and the first doped region 2 is (0.5 to 0.9):1, for example, it can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, etc. The larger the effective contact area, that is, the smaller the ineffective contact, the less metal recombination can be reduced, thereby improving the passivation effect of the battery and thus increasing the open circuit voltage.

[0075] In this application, the first surface corresponding to the first doped region 2 is a polished surface, and the polished surface has a first tower-like texture structure; the first tower-like texture structure includes a plurality of first tower bases;

[0076] The shape of the first base can be frustum or truncated pyramid, and its orthographic projection on the first surface can be a circle, triangle, quadrilateral, pentagon, hexagon, or n-sided polygon.

[0077] When the first tower base is frustum-shaped, the diameter of the side of the first tower base closest to the first surface is 0.5-1.5 μm, and the diameter of the side of the first tower base away from the first surface is 1-5 μm. The diameter of the tower base can be measured by 3D scanning.

[0078] Under a 20x microscope, within a 650μm × 650μm area, the orthographic projection of the first tower base onto the substrate is 1-10 quadrilaterals. During battery fabrication, the polishing process of the first surface corresponding to the first doped region 2 is not mirror polishing. Due to the different etching rates of silicon in different crystal orientations in the alkaline solution, a tower-like texture structure is formed. The concentration and temperature of the alkaline solution, etching time, and different additives can be controlled to reduce the activity of the alkaline solution and the size and speed of bubble generation, thereby controlling the size of the tower base.

[0079] The height of the first tower base is 0-0.3μm, excluding 0, and can be, for example, 0.3μm, 0.29μm, 0.28μm, 0.27μm, 0.26μm, 0.25μm, 0.24μm, 0.23μm, 0.22μm, 0.21μm, 0.2μm, 0.19μm, 0.18μm, 0.17μm, 0.16μm, 0.15μm, 0.14μm, 0.13μm, 0.12μm, 0.11μm, 0.1μm, 0.09μm, 0.08μm, 0.07μm, 0.06μm, 0.05μm, 0.04μm, 0.03μm, 0.02μm, 0.01μm, etc.

[0080] An excessively high or numerous first substrates can lead to increased surface roughness and unevenness, affecting the quality of subsequent film layers stacked on top of them. Conversely, an excessively small first substrate will result in increased substrate density, which in turn will affect the quality of subsequent film layers stacked on top of them. At the same time, a suitable first substrate size reduces the doping concentration of both active and non-active elements in the first doping region, thus better matching the corresponding LECO process.

[0081] The sheet resistance of the first doped region 2 is 200 ohms-500 ohms, for example, it can be 200 ohms, 250 ohms, 300 ohms, 350 ohms, 400 ohms, 450 ohms, 500 ohms, etc.

[0082] Sheet resistance, also known as film resistance, is a measurement used to indirectly characterize the thermal infrared properties of vacuum-deposited films on samples such as thin films and glass coatings. This value can be directly converted into thermal infrared emissivity. The sheet resistance is independent of the sample size, and its unit is Siements / sq (later expanded to ohms / sq). This unit is directly translated as sheet resistance or surface resistance, and when used for film layer measurements, it is also called film layer resistance.

[0083] Within a depth range of 0.1-0.4 μm from the first surface, the first doped region 2 has the maximum doping concentration of the active element; that is, the distance between the location of the maximum doping concentration of the active element in the first doped region 2 and the first surface is 0.1-0.4 μm, for example, it can be 0.1 μm, 0.12 μm, 0.15 μm, 0.17 μm, 0.2 μm, 0.22 μm, 0.25 μm, 0.27 μm, 0.3 μm, 0.32 μm, 0.35 μm, 0.37 μm, 0.4 μm, etc.

[0084] The closer the location of the maximum doping concentration of the active element is to the first surface, the closer the inactive elements are to the first surface. The higher the doping concentration of the inactive elements on the first surface, the easier it is to form a strong recombination region, which is difficult to remove, thus leading to a decrease in battery performance. In this application, the location of the maximum doping concentration of the active element achieves the best passivation and contact effects.

[0085] The junction depth of the first doped region 2 is 1-1.5 μm, for example, it can be 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, etc.

[0086] The depth difference between the location of the maximum doping concentration and the first surface and the junction depth and the first surface is 0.9-1.3 μm, for example, it can be 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, etc.

[0087] The doping concentration of the active element on the first surface corresponding to the first doped region 2 is 1E18-7E18, for example, it can be 1E18, 2E18, 3E18, 4E18, 5E18, 6E18 or 7E18, etc.

[0088] In this application, as Figure 1 As shown, the first surface corresponding to the first doped region 2 has a textured surface, which is a first pyramidal textured structure. The height of the first pyramidal textured structure is 0.5-3μm, for example, it can be 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, 2.6μm, 2.7μm, 2.8μm, 2.9μm, 3μm, etc. During the battery fabrication process, the height of the first pyramidal texture structure is 0.5-3 μm. At this height, the diffusion of dopant elements has the least impact on the first pyramidal texture structure during the fabrication of the first doped region. The first pyramidal texture structure can balance reflectivity and also bring a smaller tip area and a smaller high-composite area of ​​metal contact during the subsequent fabrication of the first electrode.

[0089] Within a depth range of 0.05-0.3 μm from the first surface, the first doped region 2 has the maximum doping concentration of the active element. That is, the distance between the location of the maximum doping concentration of the active element in the first doped region 2 and the first surface is 0.05-0.3 μm, for example, it can be 0.05 μm, 0.06 μm, 0.07 μm, 0.08 μm, 0.09 μm, 0.1 μm, 0.11 μm, 0.12 μm, 0.13 μm, 0.14 μm, 0.15 μm, 0.16 μm, 0.17 μm, 0.18 μm, 0.19 μm, 0.2 μm, 0.21 μm, 0.22 μm, 0.23 μm, 0.24 μm, 0.25 μm, 0.26 μm, 0.27 μm, 0.28 μm, 0.29 μm, 0.3 μm, etc.

[0090] The maximum doping concentration of the active element plays a major role in the subsequent formation of the contact between the first electrode and the first doped region. Within the depth range of the maximum doping concentration of the active element, the first electrode and the first doped region achieve the optimal contact resistivity, which is beneficial for the collection of photocurrent. The distance between the location of the maximum doping concentration in the first doped region 2 and the first surface is 0.05-0.3 μm. Within this depth range, the transport gain of the active element is the greatest, and the near-surface recombination loss caused by the non-active element is the smallest.

[0091] The junction depth of the first doped region 2 is 0.8-1.2 μm, for example, it can be 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, etc.

[0092] The depth difference between the location of the maximum doping concentration of the active element and the depth of the junction from the first surface is 0.5-0.8 μm, for example, it can be 0.5 μm, 0.55 μm, 0.6 μm, 0.65 μm, 0.7 μm, 0.75 μm, 0.8 μm, etc.

[0093] The regions from the location of the maximum doping concentration of the active element to the first surface and from the location of the maximum doping concentration of the active element to the substrate are the two main regions involved in conduction. However, the region from the location of the maximum doping concentration of the active element to the first surface has the greatest recombination effect. Therefore, by adjusting the ratio of the depth from the location of the maximum doping concentration of the active element to the first surface to the total junction depth, the influence of surface recombination can be minimized while ensuring contact.

[0094] The doping concentration of the active element on the first surface corresponding to the first doped region 2 is 1E18-7E18, for example, it can be 1E18, 2E18, 3E18, 4E18, 5E18, 6E18 or 7E18, etc.

[0095] In this application, as Figure 3 As shown, a first passivation layer and a first electrode 3 are disposed on the side of the first doped region 2 away from the second surface. The first passivation layer covers the first doped region 2. The first electrode 3 includes a current collector 9 extending along a second direction and arranged along a first direction. A portion of the current collector 9 passes through the first passivation layer along the second direction and contacts the first doped region 2. The second direction intersects the first direction; in some embodiments, the first direction is perpendicular to the second direction. This design can prevent excessive metal from the first electrode from entering the substrate and diffusing downwards or to both sides, resulting in significant metal recombination losses.

[0096] The first electrode 3 further includes an interconnect portion 10, which is electrically connected to the current collector electrode 9. The interconnect portion 10 is arranged along a second direction. The interconnect portion 10 is located on the surface of the first passivation layer away from the first doped region 2. The current collector electrode 9 includes a current collector portion, which is adjacent to the junction of the interconnect portion 10 and the current collector electrode 9 along the second direction. It is located on the surface of the first passivation layer away from the first doped region 2, or within the first passivation layer. Along the second direction, the size of the current collector portion is less than or equal to one-third of the spacing between adjacent interconnect portions 10. This interconnect portion can prevent a large number of first electrodes at the intersection from damaging the contact between the first passivation layer and the underlying first doped region, causing more severe metal recombination.

[0097] The first electrode 3 also includes a main electrode 8, which extends along a first direction and is arranged along a second direction. The main electrode 8 is connected to the current collector electrode 9 via an interconnect portion 10. The size of the interconnect portion can be greater than or equal to the size of the current collector electrode. When the size of the interconnect portion 10 is equal to the size of the current collector electrode 9, a non-welding process can be used to achieve the interconnection of the back contact battery, such as a film coating process, in which a carrier film with the conductive interconnect portion attached is directly bonded to the surface of the back contact battery and pressed together to form an electrical interconnect. For example, the interconnect portion 10 can be a bus electrode or an interconnect portion disposed on the bus electrode.

[0098] In this document, the dimensions of the interconnect portion can be its length, width, or diameter. The dimensions of the collector electrode can be its length, width, or diameter. For example, the width of the interconnect portion can be greater than the width of the collector electrode. For example, the length of the interconnect portion can be equal to the length of the collector electrode.

[0099] In this application, both the active and inactive elements are Group IIIA or Group VA elements.

[0100] The active and inactive elements are the same dopant elements.

[0101] In some implementations, both the activating element and the non-laser element are boron.

[0102] In this application, the battery further includes a second doped region located on the first surface. The first doped region 2 and the second doped region are arranged alternately, and the conductivity type of the second doped region is opposite to that of the first doped region 2. The first surface corresponding to the first doped region 2 has a first tower-like texture structure. The first surface corresponding to the second doped region has a second tower-like texture structure. The second tower-like texture structure includes a plurality of second towers.

[0103] During the battery fabrication process, the polishing process of the first surface corresponding to the second doped region is not mirror polishing. Due to the different corrosion rates of silicon in different crystal orientations in the alkaline solution, a tower-like texture structure is formed. The concentration and temperature of the alkaline solution, etching time, and different additives can be used to reduce the activity of the alkaline solution and the size and speed of the generated bubbles, thereby controlling the size of the tower base.

[0104] The number and size of the second substrate per unit area can be determined according to actual needs. Too many second substrates per unit area will lead to increased roughness and unevenness of the first surface, affecting the quality of the membrane layers subsequently stacked on top. Too few second substrates will lead to increased density of the second substrates, which will also affect the quality of the membrane layers subsequently stacked on top.

[0105] The one-dimensional dimension of the second tower base is greater than or equal to the one-dimensional dimension of the first tower base;

[0106] The one-dimensional dimension of the second tower base is the dimension of the side surface of the second tower base away from the base;

[0107] Under this matching, the diffusion process of the dopant element has minimal impact on the first pyramidal texture structure during the fabrication of the first doped region. This first pyramidal texture structure balances reflectivity and provides a smaller tip area and a smaller high-composite area in the subsequent fabrication of the first electrode contact. Simultaneously, a suitable pyramid size correspondingly reduces the doping concentration of both active and non-active elements within the first doped region, thus better matching the corresponding LECO process. The second doped region employs a second pyramidal base structure. If the second pyramidal base is too high, the roughness of the corresponding first surface increases, resulting in an uneven surface and affecting the quality of the subsequent film layers stacked on top. Conversely, if the second pyramidal base is too small, its density increases, also affecting the quality of the subsequent film layers stacked on top. In this paper, the one-dimensional dimension can be determined based on the orthographic projection shape of the second pyramidal base onto the substrate. For example, when the orthographic projection of the second pyramidal base onto the substrate is a circle, the one-dimensional dimension refers to the diameter of the circle; when the orthographic projection of the second pyramidal base onto the substrate is a rectangle, the one-dimensional dimension can be the diagonal length or length of the rectangle.

[0108] The height of the second tower base is less than or equal to the height of the first tower base.

[0109] The films formed on the surfaces of the first and second substrates are different, thus requiring different morphologies for the substrates. For the second doped region, the size of the second substrate needs to be as small as possible to ensure that the tunneling layer prepared on this morphology has higher quality. However, for the first doped region, the first substrate with certain undulations can increase the area of ​​the first doped region. At the same time, the morphology of the first substrate will affect the morphology of the second substrate. The first substrate is prepared first, and the second substrate corresponding to the second doped region is prepared on the basis of the first substrate.

[0110] The first tower base needs to minimize current loss due to reflection, while the second tower base needs to minimize the composite loss during transmission caused by the collection process. Because the texturing process is not very uniform, in practice, the height of the second tower base is less than or equal to the height of the first tower base. At this time, the number of tower bases is reduced, and the composite loss caused by transmission is minimized.

[0111] In this application, the battery further includes a second doped region located on the first surface, with the first doped region 2 and the second doped region arranged alternately; the conductivity type of the second doped region is opposite to that of the first doped region 2; the first surface corresponding to the first doped region 2 has a first pyramid-shaped texture structure, and the first surface corresponding to the second doped region has a second pyramid-shaped texture structure; the second pyramid-shaped texture structure includes a plurality of second pyramid bases.

[0112] During the battery fabrication process, the polishing process of the first surface corresponding to the second doped region is not mirror polishing. Due to the different corrosion rates of silicon in different crystal orientations in the alkaline solution, a tower-like texture structure is formed. The concentration and temperature of the alkaline solution, etching time, and different additives can be used to reduce the activity of the alkaline solution and the size and speed of the generated bubbles, thereby controlling the size of the tower base.

[0113] The number and size of the second substrate per unit area can be determined according to actual needs. Too many second substrates per unit area will lead to increased roughness and unevenness of the first surface, affecting the quality of the membrane layers subsequently stacked on top. Too few second substrates will lead to increased density of the second substrates, which will also affect the quality of the membrane layers subsequently stacked on top.

[0114] The one-dimensional dimension of the second tower base is smaller than the one-dimensional dimension of the base of the first pyramid-shaped textured structure; the one-dimensional dimension of the second tower base is the dimension of the side surface of the second tower base away from the base;

[0115] The one-dimensional dimension of the base of the first pyramid-shaped texture structure is the one-dimensional dimension of the orthographic projection of the base of the first pyramid-shaped texture structure onto the substrate.

[0116] The height of the second base is less than the height of the first pyramid-shaped texture structure, which is beneficial for preparing gap regions that are easy to passivate.

[0117] In this application, the battery further includes a second doped region and a first passivation layer. The second doped region is located on the first surface, and the first doped region 2 and the second doped region are arranged alternately. The second doped region has the opposite conductivity type to the first doped region 2. There is a gap region between the first doped region 2 and the second doped region. The roughness of the first surface corresponding to the gap region is 0-1 μm, for example, it can be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, or 1 μm. The first passivation layer covers the gap region. The passivation of the first surface of the gap region is achieved through the combined action of field passivation and hydrogen passivation of the first passivation layer (alumina and silicon nitride). However, excessive roughness will lead to poor film quality of the first passivation layer.

[0118] The width of the gap region is 10μm-60μm, for example, it can be 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, etc.

[0119] In some embodiments, the first surface corresponding to the first doped region 2 is a first tower-like textured structure; the height difference between the first surface corresponding to the gap region and the first surface corresponding to the first doped region 2 is 0.5-6 μm, for example, it can be 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, etc.

[0120] In some embodiments, the first surface corresponding to the first doped region 2 is a first pyramidal texture structure; the height difference between the first surface corresponding to the gap region and the first surface corresponding to the first doped region 2 is 0.5-8 μm, for example, it can be 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, 2.6μm, 2.7μm, 2.8μm, 2.9μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm, 6μm, 7μm, 7.5μm, 8μm, etc.

[0121] The passivation of the first surface of the interstitial region is achieved through the combined effects of field passivation and hydrogen passivation of the first passivation layer (alumina and silicon nitride). The first surface of the interstitial region is lower than the first surface of the first doped region 2, thus forming a pit in the interstitial region. This increases the contact area between the first surface of the interstitial region and alumina and hydrogen, suspending the passivated surface and strengthening the passivation of the first surface. If the pit is too deep, the alumina in that region will be relatively thin, resulting in a poorer alumina passivation effect. If the pit is too shallow, the original first doped region within the pit cannot be completely removed during battery fabrication, and the residue will form a high-strength recombination center with the new diffusion layer during the fabrication of the second doped region.

[0122] In this application, the second doped region includes a tunneling layer 5 and a second silicon-doped layer; one side surface of the tunneling layer 5 is stacked on the first surface of the substrate, and the other side surface is stacked with the second silicon-doped layer.

[0123] The second silicon-doped layer can be one of the following: an n-type doped polycrystalline silicon layer, an n-type doped amorphous silicon layer, an n-type doped microcrystalline silicon layer, or an n-type doped silicon carbide layer, including but not limited to these.

[0124] The thickness of the second silicon-doped layer is 50nm-400nm, for example, it can be 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm, 200nm, 210nm, 220nm, 230nm, 240nm, 250nm, 260nm, 270nm, 280nm, 290nm, 300nm, 310nm, 320nm, 330nm, 340nm, 350nm, 360nm, 370nm, 380nm, 390nm, 400nm, etc.

[0125] The roughness of the first surface corresponding to the second doped region is less than or equal to 0.5 μm, that is, the roughness of the silicon substrate 1 at the junction with the tunneling layer 5 is less than or equal to 0.5 μm. For example, it can be 0.5 μm, 0.49 μm, 0.48 μm, 0.47 μm, 0.46 μm, 0.45 μm, 0.44 μm, 0.43 μm, 0.42 μm, 0.41 μm, 0.40 μm, 0.39 μm, etc. In some embodiments, the roughness of the first surface corresponding to the second doped region is less than or equal to 0.45 μm; the roughness of the first surface corresponding to the second doped region is less than or equal to 0.4 μm. Low roughness is beneficial for growing a denser tunneling layer, resulting in better chemical passivation and transport effects.

[0126] In this article, roughness refers to the difference between the highest and lowest points. Roughness can be measured using 3D scanning.

[0127] Specifically, the solar cell is a BC cell, with a second doped region sequentially stacked on the first surface of the substrate. The second doped region and the first doped region 2 are sequentially spaced on the first surface. The second doped region includes a tunneling layer 5 and a second silicon-doped layer 4 sequentially stacked. The tunneling layer 5 is stacked with the substrate, and a second electrode 6 is disposed on the second silicon-doped layer 4. The conductivity type of the second silicon-doped layer 4 is opposite to that of the first doped region 2. The doping element in the first doped region 2 is boron, and the doping element in the second silicon-doped layer 4 is phosphorus. The substrate is a silicon substrate 1.

[0128] A second passivation layer is stacked on the second surface of the silicon substrate 1. A first passivation layer covering the second silicon doped layer 4 and the first doped region 2 is stacked on the side of the second silicon doped layer 4 away from the silicon substrate 1. The first electrode 3 penetrates the second passivation layer and extends into the first doped region 2. The second electrode 6 penetrates the second passivation layer and contacts the second silicon doped layer 4.

[0129] There is a gap region between the first doped region 2 and the second doped region, and the width of the gap region is 10μm-60μm.

[0130] The roughness of the first surface of the silicon substrate 1 within the spacer region is 0-1 μm, for example, it can be 0, 0.2 μm, 0.4 μm, 0.6 μm, 0.8 μm, 1 μm, etc.

[0131] The roughness of the first surface of the silicon substrate 1 in which the tunneling layer 5 is stacked is 0-0.5 μm, for example, it can be 0 μm, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, etc.

[0132] The silicon substrate 1 can be either an n-type silicon substrate 1 or a p-type silicon substrate 1.

[0133] In some embodiments, the light-facing surface of the silicon substrate 1 has a textured surface, while the back-facing surface is a polished surface.

[0134] In some embodiments, both the light-facing and back-facing surfaces of the silicon substrate 1 have a textured surface.

[0135] In some embodiments, a portion of the back surface of the silicon substrate 1 has a textured surface, while another portion has a polished surface.

[0136] The thickness of the first doped region 2 is 400nm-3μm, for example, it can be 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm, 750nm, 800nm, 900nm, 950nm, 1μm, 1.2μm, 1.4μm, 1.6μm, 1.8μm, 2μm, 2.2μm, 2.4μm, 2.6μm, 2.8μm, 3μm, etc.

[0137] The second silicon-doped layer 4 can be one of the following: an n-type doped polycrystalline silicon layer, an n-type doped amorphous silicon layer, an n-type doped microcrystalline silicon layer, or an n-type doped silicon carbide layer, including but not limited to these.

[0138] The thickness of the second silicon-doped layer 4 is 50nm-400nm.

[0139] The tunneling layer 5 is a silicon oxide layer with a thickness of 1-2 nm.

[0140] The first passivation layer includes a silicon nitride layer (SiNx, where x can be any value) and an aluminum oxide layer (AlOx, where x can be any value) stacked sequentially, wherein the side of the silicon nitride layer away from the aluminum oxide layer is stacked together with the silicon substrate 1.

[0141] The thickness of the silicon nitride layer is 50nm-130nm, and the thickness of the aluminum oxide layer is 2nm-15nm.

[0142] The second passivation layer includes a silicon nitride layer (SiNx, where x can be any value) and an aluminum oxide layer (AlOx, where x can be any value) stacked sequentially, wherein the side of the silicon nitride layer away from the aluminum oxide layer is stacked together with the first doped region 2 and the second silicon-containing doped layer 4.

[0143] The thickness of the silicon nitride layer is 50nm-130nm, and the thickness of the aluminum oxide layer is 2nm-15nm.

[0144] The first electrode 3 and the second electrode 6 can be made of silver, copper, aluminum, or their alloys. The first electrode 3 and the second electrode 6 can be the same or different.

[0145] In this application, the battery also includes a second doped region located on the second surface. The second doped region includes a tunneling layer 5 and a second silicon-containing doped layer 4 stacked sequentially, and the conductivity type of the first doped region 2 is opposite to that of the second doped region.

[0146] Specifically, when the solar cell is a TOPcon cell, the second surface of the substrate has a tunneling layer 5, a second silicon-doped layer 4, and a second electrode 6 stacked sequentially. The second surface has a third tower-like textured structure, and the doping type of the first doped region 2 is opposite to that of the second silicon-doped layer 4. The first surface of the substrate has a first doped region 2, on which a first electrode 3 is disposed. A first passivation layer is stacked on the side of the first doped region 2 facing away from the substrate, and a second passivation layer is stacked on the side of the second silicon-doped layer 4 facing away from the substrate. The first electrode 3 penetrates the first passivation layer and is connected to the first doped region 2, and the second electrode 6 penetrates the second passivation layer and is connected to the second silicon-doped layer 4.

[0147] The first pyramid-shaped texture structure balances reflectivity and provides a smaller tip area and a smaller high-composite area in the subsequent contact process of the first electrode. At the same time, the appropriate pyramid size reduces the doping concentration of active and non-active elements in the first doped region, thus better matching the corresponding LECO process. The second surface has a third pyramid-shaped texture structure. If the third pyramid is too high, the roughness of the first surface corresponding to the second doped region will increase, resulting in an uneven surface and affecting the quality of the film layer subsequently stacked on top of it. If the third pyramid is too small, the density of the third pyramid will increase, which will also affect the quality of the film layer subsequently stacked on top of it.

[0148] For a description of the substrate, the second silicon-doped layer 4, the first passivation layer and the second passivation layer, the first electrode 3 and the second electrode 6, please refer to the description in the aforementioned BC cell.

[0149] This application provides a method for preparing a solar cell, comprising the following steps:

[0150] Provide a substrate; the substrate has a first surface and a second surface disposed opposite to each other;

[0151] The dopant element enters the substrate from the first surface of the substrate, thereby forming the first doped region 2;

[0152] In the first doped region 2, the doping concentration of the non-active element is 1E19 to 1E22, and the doping concentration of the active element is 1E17 to 8E18. In the first doped region 2, from the direction near the first surface to the substrate, the doping concentration of the active element first increases and then decreases. The difference between the maximum doping concentration of the active element and the doping concentration of the active element at the first surface is 1E18 to 7E18.

[0153] After the first doped region 2 is formed, a first electrode 3 is formed on the first doped region 2, and the first electrode 3 extends at least partially into the first doped region 2.

[0154] In the step of forming the first electrode 3, the first electrode precursor is first formed, and then the first electrode precursor and the first doped region 2 are processed using the LECO process.

[0155] LECO (Laser-enhanced contact optimization) is an advanced laser sintering technology that precisely and locally disrupts the passivation layer, promoting electron transport between the metal electrode and silicon. The LECO process applies high-intensity laser pulses locally to the front or back of the solar cell while maintaining a constant reverse voltage. The resulting localized current significantly reduces the contact resistivity between the semiconductor and the metal electrode.

[0156] When the first surface corresponding to the first doped region 2 has a first pyramidal texture structure, the diameter of the laser spot used in the LECO process is less than or equal to the distance between the highest points of two adjacent pyramidal apexes in the first pyramidal texture structure.

[0157] When the first surface corresponding to the first doped region 2 has a first tower-like texture structure, the diameter of the laser spot used in the LECO process is less than or equal to the distance between two adjacent first tower geometric centers in the first tower-like texture structure.

[0158] Specifically, when the solar cell is a BC cell, the fabrication method of the solar cell includes the following steps:

[0159] Step 1: Provide a silicon substrate 1; the silicon substrate 1 has a first surface and a second surface disposed opposite to each other;

[0160] Step 2: Polish or texturize the first surface (backlight surface) of the silicon substrate 1 to diffuse dopant elements, thereby forming the first doped region 2.

[0161] Step 3: First patterning, forming the first patterned doped region 2.

[0162] The first graphical representation will be done using conventional methods, without specifics or limitations, such as using laser grooving or masking.

[0163] When using laser grooving for imaging, the unit energy density of the laser can be adjusted specifically. By adjusting the laser's power, frequency, velocity, and the type of light source, the energy density can be adjusted to around 0.3 J / m². 3 -2 J / m 3 The reflectivity of the laser light in this battery structure was adjusted to achieve a reflectivity of 1%-5% on the textured surface and 5%-25% on the polished surface. This achieved the best film removal effect and low damage effect. The criterion for this judgment is the PL test, where the PL measurement decreased by 1%-5% after laser treatment.

[0164] When using the masking method, the mask is an oxide with a thickness of 5nm-100nm. The main component of the oxide is silicon dioxide, and the boron content in the oxide is 0-20%. Alternatively, it can be used in conjunction with other masking films, such as commonly used wax printing or offset printing. Its main advantage is that the masking film with this composition can be completely removed in less than 120 seconds under low concentrations of HF (1%-5%), or completely removed in 240 seconds under low concentrations of alkali NaOH or KOH (2%-10%), without the use of additives or the introduction of other impurities.

[0165] After the first patterning is completed, a plurality of first doped regions 2 are spaced apart on the first surface of the silicon substrate 1, while the exposed silicon substrate forms a polished surface.

[0166] Step 4: A full-layer tunneling layer 5 and a second silicon-doped layer 4 are formed on the surface of the first doped region 2 away from the silicon substrate 1 and on the exposed silicon substrate 1.

[0167] The fabrication processes of the tunneling layer 5 and the second silicon-doped layer 4 are conventional and are not further limited here. For example, the tunneling layer 5 can be formed by POLY and the second silicon-doped layer 4 can be formed by LPCVD.

[0168] Step 5: Second patterning: Forming a patterned tunneling layer 5 and a second silicon-doped layer 4.

[0169] The second graphical representation uses conventional methods, without specific limitations, such as laser grooving and cleaning or masking.

[0170] During the second patterning process, the tunneling layer 5 and the second silicon-doped layer 4 located on the first doped region 2 are removed, and the tunneling layer 5 and the second silicon-doped layer 4 in the gap region between the first doped region 2 and the second silicon-doped layer 4 are also removed.

[0171] Step Six: Passivation layers 7 are formed on the second surface (light-facing surface) of the silicon substrate 1 and on the surface of the second silicon-doped layer 4 away from the silicon substrate 1. The passivation layer 7 on the light-facing surface of the silicon substrate 1 is the second passivation layer, and the passivation layer 7 on the first doped region 2 and the second silicon-doped layer 4 is the first passivation layer. The fabrication process of the passivation layer 7 is conventional and is not further limited here. For example, the passivation layer can be formed by PECVD.

[0172] Step 7: Form the first electrode 3 and the second electrode 6.

[0173] First, a first electrode precursor is formed on the surface of the first passivation layer away from the first doped region using a screen printing process, and a second electrode is formed on the surface of the first passivation layer away from the second doped region. Then, the first electrode 3 and the first doped region 2 are processed using the LECO process, thereby forming a first electrode 3 and a second electrode 6 that penetrate the first passivation layer on the first passivation layer. The portion of the first electrode 3 that penetrates the first passivation layer extends into the first doped region 2, and the second electrode 6 penetrates the first passivation layer and contacts the second silicon-doped layer 4.

[0174] The laser used in the LECO process is either green or infrared light, with a reverse bias voltage between 2V and 15V, and the scanning method is either front scanning or back scanning.

[0175] When the first surface corresponding to the first doped region 2 has a first pyramidal texture structure, the diameter of the laser spot used in the LECO process is less than or equal to the distance between the two highest points of the first pyramidal texture structure.

[0176] When the first surface corresponding to the first doped region 2 has a first tower-like texture structure, the diameter of the laser spot used in the LECO process is less than or equal to the distance between the geometric centers of two adjacent first tower bases in the first tower-like texture structure. The LECO process can improve the contact performance between the first electrode 3 and the first doped region 2, thereby improving the electrical performance of the cell. Compared with the prior art that does not use the LECO process, the solar cell of this application has a lower series resistance, higher flyback distance (FF), higher open-circuit voltage, and higher cell efficiency.

[0177] Specifically, when the solar cell is a TOPcon cell, the fabrication method of the solar cell includes the following steps:

[0178] Step 1: Provide a silicon substrate 1; the silicon substrate 1 has a first surface and a second surface disposed opposite to each other;

[0179] Step 2: Diffusion of doping elements is performed on the first surface (light-facing surface) of the silicon substrate 1 to form the first doped region 2;

[0180] Step 3: A tunneling layer 5 and a second silicon-doped layer 4 are sequentially formed on the second surface (backlight side) of the silicon substrate 1;

[0181] Step 4: A first passivation layer is formed on the surface of the first doped region 2 facing away from the silicon substrate 1, and a second passivation layer is formed on the surface of the second silicon doped layer 4 facing away from the silicon substrate 1.

[0182] Step 5: A second electrode 6 is formed on the side of the second passivation layer facing away from the silicon substrate 1, and the second electrode 6 passes through the second passivation layer and connects to the second silicon-doped layer 4; simultaneously, a first electrode precursor is formed on the side of the first passivation layer facing away from the first doped region using a screen printing process, and then the first electrode 3 and the first doped region 2 are processed using the LECO process.

[0183] The LECO process can improve the contact performance between the first electrode 3 and the first doped region 2, thereby improving the electrical performance of the cell. Compared with existing technologies that do not employ the LECO process, the solar cell of this application exhibits reduced series resistance, increased flyback distance (FF), increased open-circuit voltage, and improved cell efficiency.

[0184] When the first surface corresponding to the first doped region 2 has a first pyramidal texture structure, the diameter of the laser spot used in the LECO process is less than or equal to the distance between the two highest points of the first pyramidal texture structure.

[0185] When the first surface corresponding to the first doped region 2 has a first tower-like texture structure, the diameter of the laser spot used in the LECO process is less than or equal to the distance between the geometric centers of two adjacent first tower bases in the first tower-like texture structure. The LECO process can improve the contact performance between the first electrode 3 and the first doped region 2, thereby improving the electrical performance of the cell. Compared with the prior art that does not use the LECO process, the solar cell of this application has a lower series resistance, higher flyback distance (FF), higher open-circuit voltage, and higher cell efficiency.

[0186] The preparation method of this application produces a solar cell as described above.

[0187] This application provides a photovoltaic module, including the aforementioned solar cell.

[0188] This application provides a photovoltaic system, including the aforementioned photovoltaic module.

[0189] Example

[0190] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0191] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0192] Example 1

[0193] The BC solar cell of this embodiment includes the following steps:

[0194] Step 1: Provide a silicon substrate 1; the silicon substrate has a first surface and a second surface disposed opposite to each other;

[0195] The single-crystal silicon wafer is an N-type silicon wafer. A texturing and cleaning process is performed on both sides of the N-type silicon wafer to give the first surface a first pyramid-shaped texture structure with a height of 1-3 μm.

[0196] Step 2: Boron is used to diffuse dopant onto the first surface (backlight surface) of the silicon substrate 1, thereby forming the first doped region 2. Within the first doped region 2, the minimum doping concentration of non-activated boron is 1E19, and the maximum doping concentration within a 0.3 μm depth range from the first surface is 1E22, with a doping concentration of 5E20 at the first surface. The minimum doping concentration of activated boron is 1E17, and the maximum doping concentration within a 0.3 μm depth range from the first surface is 8E18, with a doping concentration of 5E18 at the first surface. Furthermore, within the first doped region 2, the doping concentration of activated boron first increases and then decreases in the direction from the first surface into the substrate. The difference between the maximum doping concentration of activated boron and the doping concentration of activated boron at the first surface is 3E18. The junction depth of the first doped region 2 is 0.8 μm, and the sheet resistance of the first doped region 2 is 200 ohms.

[0197] Step 3: First patterning, forming the first patterned doped region 2.

[0198] When imaging using laser grooving, a first laser is used to irradiate all areas on the first surface except for the intended retained first doped region 2, etching away the first doped region 2 in all areas except for the intended retained first doped region 2, thereby exposing the silicon substrate. The first laser is a picosecond laser with an energy density of 200 MJ / m². 2 After the first patterning is completed, a plurality of first doped regions 2 are spaced apart on the first surface of the silicon substrate 1. The width of the first doped region 2 is 250 μm, and the exposed silicon substrate has a second tower-like textured structure.

[0199] Step 4: Form a continuous tunneling layer 5 and a second silicon-doped layer 4 on the surface of the first doped region 2 away from the silicon substrate 1. The tunneling layer 5 can be formed by POLY process, and the second silicon-doped layer 4 can be formed by LPCVD process. The tunneling layer 5 is a silicon oxide layer with a thickness of 2 nm. The second silicon-doped layer 4 is a phosphorus-doped polycrystalline silicon layer with a thickness of 100 nm.

[0200] Step 5: Second patterning: Forming a patterned tunneling layer 5 and a second silicon-doped layer 4.

[0201] The second laser is used to irradiate the first doped region 2 and the second silicon doped layer corresponding to the preset gap region. The instantaneous high temperature of the laser plays a role in opening the film. Then, the second silicon doped layer and tunneling layer above the first doped region and the second silicon doped layer and tunneling layer in the gap region are etched away, thereby forming a patterned tunneling layer 5 and second silicon doped layer 4.

[0202] The second laser is a picosecond laser with an energy density of 200 MJ / m². 2 .

[0203] The width of the second silicon-doped layer 4 and the tunneling layer 5 is 250 μm.

[0204] The height difference between the first surface corresponding to the gap region and the first surface corresponding to the first doped region 2 is 2 μm; the height difference between the first surface corresponding to the tunneling layer 5 and the first surface corresponding to the first doped region 2 is 3 μm.

[0205] The roughness of the first surface corresponding to the gap region is 1 μm;

[0206] The roughness of the first surface corresponding to the second doped region is 0.5 μm.

[0207] Step Six: Passivation layers 7 are formed on the second surface (light-facing surface) of the silicon substrate 1 and on the surface of the second silicon-doped layer 4 away from the silicon substrate 1. The passivation layer 7 on the light-facing surface of the silicon substrate 1 is the second passivation layer, and the passivation layer 7 on the first doped region 2 and the second silicon-doped layer 4 is the first passivation layer. The passivation layers can be formed by PECVD. The passivation layers are silicon nitride and aluminum oxide layers, with a silicon nitride layer thickness of 100 nm and an aluminum oxide layer thickness of 5 nm. In the first passivation layer, the surface of the silicon nitride layer away from the aluminum oxide layer is stacked with the silicon substrate 1. In the second passivation layer, the surface of the silicon nitride layer away from the aluminum oxide layer is stacked with the first doped region 2 and the second silicon-doped layer 4.

[0208] Step 7: Form the first electrode 3 and the second electrode 6.

[0209] First, a first electrode precursor is formed on the surface of the first passivation layer away from the first doped region using screen printing. Simultaneously, a second electrode is formed on the surface of the first passivation layer away from the second doped region. Then, the first electrode 3 and the first doped region 2 are processed using the LECO process to form the first electrode 3 and the second electrode 6. The first electrode 3 extends into the first doped region 2 through the first passivation layer, and the second electrode 6 extends through the first passivation layer and connects to the second silicon-doped layer 4. Both the first and second electrodes are made of silver paste.

[0210] The laser used in the LECO process is green light, with a reverse bias voltage of 15V and a reverse current of 8A. The scanning method is either front-side or back-side scanning. The diameter of the laser spot is the distance between the two apexes of the first pyramidal texture structure. The LECO process improves the contact performance between the first electrode 3 and the first doped region 2, thereby enhancing the cell's electrical performance. Compared to existing technologies that do not employ the LECO process, the solar cell of this application exhibits reduced series resistance, increased flyback distance (FF), increased open-circuit voltage, and improved cell efficiency.

[0211] The performance of the solar cell in this embodiment is shown in Table 1.

[0212] The only difference between the solar cells in Examples 2-4 and the solar cells in Example 1 is that the parameters in the LECO process are different, specifically the reverse bias voltage.

[0213] The performance of the solar cell in this embodiment is shown in Table 1.

[0214] The only difference between the solar cells of Example 5 and Comparative Examples 3-4 and the solar cell of Example 1 is that the doping concentration of the maximum active element in the first doping region is different.

[0215] The performance of the solar cell in this embodiment is shown in Table 1.

[0216] The solar cells of Example 6 and Comparative Example 5 differ from the solar cell of Example 1 only in that the difference between the maximum doping concentration of the active element in the first doped region and the doping concentration of the active element at the first surface is different.

[0217] The performance of the solar cell in this embodiment is shown in Table 1.

[0218] The difference between the solar cell in Example 7 and Example 1 lies only in steps one and two. Steps one and two of this example are as follows:

[0219] Step 1: Provide a silicon substrate 1; the silicon substrate has a first surface and a second surface disposed opposite to each other;

[0220] The single-crystal silicon wafer is an N-type silicon wafer. Both sides of the N-type silicon wafer are polished to give the first surface a first tower-like texture structure. Under a 20x microscope, within an area of ​​650μm×650μm, the first tower base is projected onto the substrate as a quadrilateral of 1-10, and the height of the first tower base is 0-0.3μm.

[0221] Step 2: Boron is used to diffuse dopant onto the first surface (backlight surface) of the silicon substrate 1, thereby forming a first doped region 2. Within the first doped region 2, the minimum doping concentration of non-activated boron is 1E19, and the maximum doping concentration within a depth of 0.35 μm from the first surface is 1E22, with a doping concentration of 5E20 at the first surface. The minimum doping concentration of activated boron is 1E17, and the maximum doping concentration within a depth of 0.35 μm from the first surface is 8E18, with a doping concentration of 5E18 at the first surface. Furthermore, within the first doped region 2, the doping concentration of activated boron first increases and then decreases in the direction from the first surface into the substrate. The difference between the maximum doping concentration of activated boron and the doping concentration of activated boron at the first surface is 3E18. The junction depth of the first doped region 2 is 1.4 μm, and the sheet resistance of the first doped region 2 is 200 ohms.

[0222] The performance of the solar cell in this embodiment is shown in Table 1.

[0223] Comparative Example 1

[0224] The only difference between the solar cell of Comparative Example 1 and the solar cell of Example 1 is that the LECO process is not performed. The performance of the solar cell of this comparative example is shown in Table 1.

[0225] Comparative Example 2

[0226] The only difference between the solar cell of Comparative Example 2 and the solar cell of the embodiment is that the first doped region 2 in the solar cell of Comparative Example 2 has the structure of a first tunneling layer + a first doped layer. The first tunneling layer 5 is silicon oxide with a thickness of 2nm. The first doped layer is a p-type polycrystalline silicon doped layer with a thickness of 100nm.

[0227] The performance of the solar cells in this comparative example is shown in Table 1.

[0228] The electrical performance parameters in Table 1 were obtained by testing with an IV tester.

[0229] Table 1 shows the parameters for each embodiment and comparative example.

[0230]

[0231]

[0232] Summary: As shown in the table above, the solar cell of this application, by adopting LECO technology, changes the contact between the first electrode and the first doped region, thereby reducing the contact resistivity between the first electrode and the first doped region. While taking into account the cell performance, the doping concentration of the active element and the doping concentration of the non-active element in the first doped region can be reduced accordingly. The doping concentration of the active element can be as low as 1E17 to 1E19. In Comparative Examples 1-3, the cell performance is low because the contact resistivity between the first electrode and the first doped region is high. Although the cell efficiency of Comparative Example 4 is high, its Voc value is lower than that of Example 1, so it cannot be used as a high-efficiency cell. Although Comparative Examples 5 and 6 have high cell efficiency, their recombination is larger and the Voc value is lower than that of Example 1, so they cannot be used as high-efficiency cells.

[0233] Although the embodiments of this application have been described above in conjunction with the accompanying drawings, this application is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, not restrictive. Those skilled in the art can make many other forms based on the guidance of this specification and without departing from the scope of protection of the claims of this application, and these are all within the scope of protection of this application.

Claims

1. A solar cell, wherein, The system includes a substrate having a first surface and a second surface disposed opposite to each other. A first doped region is located on the first surface. In the first doped region, the doping concentration of non-active elements is 1E19 to 1E22, and the doping concentration of active elements is 1E17 to 8E18. In the first doped region, in the direction from the first surface to the substrate, the doping concentration of the active elements first increases and then decreases. The difference between the maximum doping concentration of the active elements and the doping concentration of the active elements at the first surface is 1E18 to 7E18. The first surface corresponding to the first doped region has a first pyramid-shaped texture structure, and the height of the first pyramid-shaped texture structure is 0.5-3 μm; Within a depth range of 0.05-0.3 μm from the first surface, the first doped region has the maximum doping concentration of the active element; the junction depth of the first doped region is 0.8-1.2 μm. The difference between the maximum doping concentration of the active element and the depth of the junction from the first surface is 0.5-0.8 μm.

2. The solar cell according to claim 1, wherein, A first electrode is disposed on the surface of the first doped region away from the substrate, and a portion of the first electrode extends into the first doped region. The contact resistivity between the first electrode and the first doped region is 0.1–3 mΩ / cm. 2 .

3. The solar cell according to claim 1, wherein, A first passivation layer and a first electrode are disposed on the side of the first doped region away from the second surface. The first passivation layer covers the first doped region. The first electrode includes a current collector electrode extending along a second direction and arranged along a first direction. A portion of the current collector electrode passes through the first passivation layer and contacts the first doped region. The second direction intersects the first direction.

4. The solar cell according to claim 3, wherein, The first electrode further includes an interconnect portion electrically connected to the current collector electrode, the interconnect portion being arranged along the second direction; the interconnect portion is located on the surface of the first passivation layer away from the first doped region, the current collector electrode includes a current collector electrode portion adjacent to the junction of the interconnect portion and the current collector electrode along the second direction, and is located on the surface of the first passivation layer away from the first doped region or within the first passivation layer; along the second direction, the size of the current collector electrode portion is less than or equal to one-third of the spacing between adjacent interconnect portions.

5. The solar cell according to claim 1, wherein, The battery further includes a second doped region located on the first surface, and the first and second doped regions are arranged alternately; the second doped region has the opposite conductivity type to the first doped region.

6. The solar cell according to claim 1 or 5, wherein, Both the activating element and the non-laser element are boron.

7. The solar cell according to claim 1, wherein, The battery further includes a second doped region located on the first surface, and the first and second doped regions are arranged alternately. The second doped region has the opposite conductivity type to the first doped region. The first surface corresponding to the first doped region has a first pyramid-shaped texture structure, and the first surface corresponding to the second doped region has a second pyramid-shaped texture structure. The second pyramid-shaped texture structure includes a plurality of second pyramid bases. The one-dimensional dimension of the second tower base is smaller than the one-dimensional dimension of the base of the first pyramid-shaped textured structure; the one-dimensional dimension of the second tower base is the dimension of the side surface of the second tower base away from the base; The height of the second tower base is less than the height of the first pyramid-shaped texture structure.

8. The solar cell according to claim 1, wherein, The battery further includes a second doped region and a first passivation layer. The second doped region is located on the first surface, and the first doped region and the second doped region are arranged alternately. The second doped region has the opposite conductivity type to the first doped region. A gap region exists between the first doped region and the second doped region; the first passivation layer covers the gap region; The roughness of the first surface corresponding to the gap region is 0-1 μm.

9. The solar cell according to claim 1, wherein, The battery further includes a second doped region and a first passivation layer. The second doped region is located on the first surface, and the first doped region and the second doped region are arranged alternately. The second doped region has the opposite conductivity type to the first doped region. There is a gap region between the first doped region and the second doped region. The first passivation layer covers the gap region. The first surface corresponding to the first doped region has a first pyramid-shaped texture structure; The height difference between the first surface corresponding to the gap region and the first surface corresponding to the first doped region is 0.5-8 μm.

10. The solar cell according to claim 1, wherein, Both the active and inactive elements in the first doped region are Group 3 elements. The battery further includes a second doped region located on the first surface, with the first and second doped regions arranged alternately. The second doped region includes a tunneling layer and a second silicon-doped layer. One side of the tunneling layer is stacked on the first surface of the substrate, and the other side of the tunneling layer is stacked with the second silicon-doped layer. The roughness of the first surface corresponding to the second doped region is less than or equal to 0.5 μm.

11. The solar cell according to claim 1, wherein, The battery further includes a second doped region located on the second surface. The second surface has a third tower-like texture structure. The second doped region includes a tunneling layer and a second silicon-containing doped layer stacked sequentially. The conductivity type of the first doped region is opposite to that of the second doped region.

12. A method for preparing a solar cell, wherein, Includes the following steps: Provide a base; The substrate has a first surface and a second surface disposed opposite to each other; A dopant element enters the substrate from the first surface of the substrate, thereby forming a first doped region; In the first doped region, the doping concentration of the non-active element is 1E19 to 1E22, and the doping concentration of the active element is 1E17 to 8E18. In the first doped region, from the direction near the first surface to the substrate, the doping concentration of the active element first increases and then decreases. The difference between the maximum doping concentration of the active element and the doping concentration of the active element at the first surface is 1E18 to 7E18. The first surface corresponding to the first doped region has a first pyramid-shaped texture structure, and the height of the first pyramid-shaped texture structure is 0.5-3 μm; Within a depth range of 0.05-0.3 μm from the first surface, the first doped region has the maximum doping concentration of the active element; the junction depth of the first doped region is 0.8-1.2 μm. The difference between the maximum doping concentration of the active element and the depth of the junction from the first surface is 0.5-0.8 μm.

13. The preparation method according to claim 12, wherein, After the first doped region is formed, a first electrode is formed on the first doped region, and at least a portion of the first electrode extends into the first doped region.

14. The preparation method according to claim 13, wherein, Forming the first electrode includes the following steps: Forming the first electrode precursor; The first electrode precursor and the first doped region are processed using the LECO process.

15. The preparation method according to claim 14, wherein, When the first surface corresponding to the first doped region has a first pyramidal texture structure, the diameter of the laser spot used in the LECO process is less than or equal to the distance between the highest points of adjacent pyramidal peaks in the first pyramidal texture structure.

16. The preparation method according to any one of claims 12-15, wherein, The prepared solar cell is the solar cell according to any one of claims 1-11.

17. A photovoltaic module, wherein, This includes the solar cell according to any one of claims 1-11, or the solar cell prepared by any one of claims 12-15.

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