Heterojunction solar cell and manufacturing method therefor

Abstract

The present application relates to a solar cell and a manufacturing method therefor, and a photovoltaic module. The manufacturing method for the solar cell comprises: providing a substrate, wherein the substrate comprises a first surface and a second surface arranged opposite to each other in the thickness direction of the substrate; forming a tunneling passivation layer on the first surface of the substrate; and on the basis of physical vapor deposition, stacking a first doping layer and a second doping layer at least on the side of the tunneling passivation layer away from the substrate, wherein a doping type of the first doping layer and a doping type of the second doping layer are both P-type, doping elements of the first doping layer and the second doping layer are not completely the same, the first doping layer includes at least a gallium element, the second doping layer includes at least a boron element, the first doping layer and the second doping layer are both prepared by physical vapor deposition, and doping elements of the first doping layer and the second doping layer are not completely the same.

Description

Heterojunction solar cells and their fabrication methods

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese patent application filed on November 19, 2024, application number 2024116520442, entitled "Solar Cells and Methods for Preparing Themselves, Photovoltaic Modules", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of photovoltaic technology, and in particular to a solar cell and its preparation method, and a photovoltaic module. Background Technology

[0004] Currently, solar cells, a new energy technology, are experiencing unprecedented development. Among them, crystalline silicon solar cells have consistently dominated the photovoltaic industry with over 90% market share. Given this massive scale and broad market prospects, crystalline silicon solar cells are also continuously evolving.

[0005] In the process of forming a P-type doped polycrystalline silicon layer, solar cells in related technologies are mainly prepared by chemical vapor deposition (e.g., PECVD process for in-situ doping, or LPCVD process for ex-situ doping) and solution methods. Summary of the Invention

[0006] Based on this, a solar cell and its preparation method, as well as a photovoltaic module, are provided.

[0007] In a first aspect, this application provides a method for preparing a solar cell, comprising:

[0008] A substrate is provided, the substrate including a first surface and a second surface disposed opposite to each other along the thickness direction of the substrate;

[0009] A tunneling passivation layer is formed on the first surface of the substrate; and

[0010] Based on physical vapor deposition, a first doped layer and a second doped layer are stacked at least on the side of the tunneling passivation layer away from the substrate to form a first doped layer and a second doped layer, wherein the doping type of the first doped layer and the second doped layer is p-type, the doping elements of the first doped layer and the second doped layer are not completely the same, the first doped layer includes at least gallium, and the second doped layer includes at least boron.

[0011] In some embodiments, the physical vapor deposition-based formation of a first doped layer and a second doped layer at least on the side of the tunneling passivation layer away from the substrate includes:

[0012] A target unit is provided; wherein the target unit includes a gallium-doped hybrid material target and a boron-doped hybrid material target, the gallium-doped hybrid material target and the boron-doped hybrid material target are arranged in a deposition sequence;

[0013] A first doped amorphous silicon layer and a second doped amorphous silicon layer are formed on the side of the tunneling passivation layer away from the substrate by physical vapor deposition; wherein the first doped amorphous silicon layer includes at least gallium, and the second doped amorphous silicon layer includes at least boron; and

[0014] Annealing is performed to form the first doped layer and the second doped layer.

[0015] In some embodiments, the formation of a first doped amorphous silicon layer and a second doped amorphous silicon layer on the side of the tunneling passivation layer away from the substrate based on physical vapor deposition includes:

[0016] Based on the mixed gas and the target unit, the first doped amorphous silicon layer and the second doped amorphous silicon layer are formed on the tunneling passivation layer away from the substrate by magnetron sputtering; wherein, the mixed gas includes sputtering gas and doping gas.

[0017] In some embodiments, the doping gas includes a gallium source precursor and a boron source precursor.

[0018] In some embodiments, the gallium source precursor comprises trimethylgallium, and the boron source precursor comprises at least one of diboron hexahydrogenate and trimethyl borate.

[0019] In some embodiments, the doping gas further includes at least one of methane, carbon dioxide, and ammonia.

[0020] In some embodiments, the doping gas includes the methane, the carbon dioxide, and the ammonia; wherein the doping percentage of the methane is 10%-50%, the doping percentage of the ammonia is 0.5%-30%, and the doping percentage of the carbon dioxide is 0.1%-50%.

[0021] In some embodiments, the formation of a first doped layer and a second doped layer on the side of the tunneling passivation layer away from the substrate based on physical vapor deposition includes:

[0022] By bombarding each of the mixed material targets in the target unit with a high-energy electron beam in the order of deposition, the first doped amorphous silicon layer and the second doped amorphous silicon layer are deposited on the side of the tunneling passivation layer away from the substrate.

[0023] In some embodiments, the target unit includes at least two gallium-doped hybrid material targets and at least two boron-doped hybrid material targets, wherein the gallium-doped hybrid material targets are arranged adjacent to each other, and the boron-doped hybrid material targets are arranged adjacent to each other.

[0024] In some embodiments, the number of the first doped layer and the second doped layer are each at least two, and each of the first doped layer and the second doped layer is alternately formed on the side of the tunneling passivation layer away from the substrate.

[0025] In some embodiments, the first doped layer and the second doped layer are alternately formed on the side of the tunneling passivation layer away from the substrate, including:

[0026] At least two target units are provided; the target units include gallium-doped hybrid material targets and boron-doped hybrid material targets, the gallium-doped hybrid targets and the boron-doped hybrid targets are arranged in a deposition sequence;

[0027] For each target unit, a first doped amorphous silicon layer and a second doped amorphous silicon layer are formed on the target structure in the thickness direction based on physical vapor deposition; wherein, the target structure includes a tunneling passivation layer or each of the second doped amorphous silicon layers;

[0028] An annealing process is performed to form alternating first doped layers and second doped layers on the side of the tunneling passivation layer away from the substrate.

[0029] In some embodiments, before forming the first doped amorphous silicon layer, the method further includes:

[0030] An initial target is provided, wherein the initial target is disposed adjacent to the gallium-doped hybrid material target;

[0031] An interfacial amorphous silicon layer is formed on the side of the tunneling passivation layer away from the substrate based on the initial target material; wherein the first doped amorphous silicon layer is located on the side of the interfacial amorphous silicon layer away from the tunneling passivation layer.

[0032] In some embodiments, the initial target material includes an intrinsic target material undoped of P-type elements or a hybrid target material lightly doped with P-type elements.

[0033] In some embodiments, before forming the second doped amorphous silicon layer, the method further includes:

[0034] A first interface oxide layer is formed on the side of the first doped amorphous silicon layer away from the tunneling passivation layer; wherein, the second doped amorphous silicon layer is formed on the side of the first interface oxide layer away from the first doped amorphous silicon layer.

[0035] In some embodiments, after forming a first doped amorphous silicon layer and a second doped amorphous silicon layer on the target structure in the thickness direction for each of the target units, the method further includes:

[0036] A second interface oxide layer is formed on the side of the second gallium-doped amorphous silicon layer away from the first gallium-doped amorphous silicon layer.

[0037] In some embodiments, the physical vapor deposition further includes one of vacuum evaporation and arc plasma deposition.

[0038] Secondly, this application provides a solar cell, comprising:

[0039] The substrate includes a first surface and a second surface disposed opposite to each other along the thickness direction of the substrate;

[0040] A tunneling passivation layer is located on the first surface of the substrate;

[0041] The first doped layer is located on the side of the tunneling passivation layer away from the substrate;

[0042] The second doped layer is located on the side of the first doped layer away from the tunneling passivation layer;

[0043] Wherein, both the first doped layer and the second doped layer are p-type doped, and the doping elements of the first doped layer and the second doped layer are not exactly the same; the first doped layer includes at least gallium, and the second doped layer includes at least boron; and

[0044] The first electrode is in contact with the second doped layer.

[0045] In some embodiments, the doping element of the first doped layer includes gallium.

[0046] The doping element of the second doped layer includes boron, or the doping element of the second doped layer includes both boron and gallium.

[0047] In some embodiments, the solar cell includes at least two first doped layers and at least two second doped layers, wherein, in the thickness direction, each of the first doped layer and each of the second doped layers is alternately stacked on the side of the tunneling passivation layer away from the substrate.

[0048] In some embodiments, the concentration of gallium in the first doped layer gradually decreases in the direction from the second doped layer to the tunneling passivation layer.

[0049] In some embodiments, the maximum concentration of gallium in each of the first doped layers ranges from 8E19cm⁻¹. -3-12E19 / cm -3 .

[0050] In some embodiments, the concentration of boron in the second doped layer gradually decreases in the direction from the second doped layer to the tunneling passivation layer.

[0051] In some embodiments, the maximum concentration of boron in each of the second doped layers ranges from 5E19cm⁻¹. -3 -11E19 / cm -3 .

[0052] In some embodiments, the thickness of the first doped layer ranges from 10 nm to 150 nm, and the thickness of the second doped layer ranges from 5 nm to 150 nm.

[0053] In some embodiments, the solar cell further includes:

[0054] A first interface oxide layer is located between the first doped layer and the second doped layer in the thickness direction.

[0055] In some embodiments, the solar cell further includes:

[0056] The second interface oxide layer is located on the side of the second doped layer away from the first doped layer in the thickness direction.

[0057] In some embodiments, the solar cell further includes:

[0058] An interface polysilicon layer is located on the side of the tunneling passivation layer away from the substrate in the thickness direction; wherein the first doped layer is located on the side of the interface polysilicon layer away from the tunneling passivation layer.

[0059] In some embodiments, both the first doped layer and the second doped layer are prepared by physical vapor deposition.

[0060] In some embodiments, the physical vapor deposition includes one of vacuum evaporation, magnetron sputtering, reactive plasma deposition, and arc plasma deposition.

[0061] In some embodiments, the first surface is a backlight surface; wherein, the solar cell further includes:

[0062] The first passivation anti-reflection layer is located on the side of the second doped layer away from the first doped layer;

[0063] A first polysilicon conductive layer, a second passivation antireflection layer, a second polysilicon conductive layer, and a conductive passivation layer are stacked on the second surface of the substrate; wherein, the first polysilicon conductive layer and the second polysilicon conductive layer are both N-type doped.

[0064] The second electrode is disposed on one side of the second surface of the substrate and is in contact with the conductive passivation layer.

[0065] In some embodiments, the first surface is a backlight surface, and the second surface includes a first region and a second region; wherein, the solar cell further includes:

[0066] At least one third polysilicon conductive layer is stacked in the first region;

[0067] At least one third passivation and anti-reflection layer is stacked in the second region;

[0068] At least one fourth passivation antireflection layer is stacked on the side of the second doped layer away from the first doped layer;

[0069] The second electrode is disposed on one side of the second surface of the substrate and is in contact with the third polycrystalline silicon conductive layer.

[0070] In some embodiments, the first surface is a light-receiving surface, the first surface includes a first region and a second region, wherein the tunneling passivation layer is located in the first region of the first surface; wherein the solar cell further includes:

[0071] A tunneling oxide layer, a third doped layer, and a fifth passivation antireflection layer are stacked on the second surface of the substrate, wherein the doping type of the third doped layer is different from that of the first doped layer;

[0072] The sixth passivation antireflection layer is located on the side of the second doped layer away from the first doped layer and in the second region on the first surface;

[0073] The second electrode is disposed on one side of the second surface of the substrate and is in contact with the third doped layer.

[0074] Thirdly, this application provides a photovoltaic module comprising at least one battery string, wherein the battery string comprises at least two of the aforementioned solar cells, or solar cells prepared by the aforementioned method of manufacturing solar cells. Attached Figure Description

[0075] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the disclosed drawings without creative effort.

[0076] Figure 1 is a schematic diagram of the structure of a solar cell provided in an embodiment of this application.

[0077] Figure 2 is a schematic diagram of the structure of a solar cell provided in another embodiment of this application.

[0078] Figure 3A is a schematic diagram of the structure of a solar cell provided in another embodiment of this application.

[0079] Figure 3B is an enlarged schematic diagram of region I in Figure 3A.

[0080] Figure 4 is a partial schematic diagram of a solar cell in one embodiment of this application.

[0081] Figure 5 is a partial schematic diagram of a solar cell in another embodiment of this application.

[0082] Figure 6 is a partial schematic diagram of a solar cell in another embodiment of this application.

[0083] Figure 7 is a flowchart of a method for preparing a solar cell according to an embodiment of this application.

[0084] Figure 8 is a flowchart of forming a first doped layer and a second doped layer at least on the side of the tunneling passivation layer away from the substrate based on physical vapor deposition in one embodiment of this application.

[0085] Figure 9 is a schematic diagram of the arrangement of multiple targets in one embodiment of this application.

[0086] Figure 10 is a schematic diagram of the arrangement of multiple targets in another embodiment of this application.

[0087] Figure 11 is a cross-sectional view of the process of forming a first doped layer and a second doped layer at least on the side of the tunneling passivation layer away from the substrate based on physical vapor deposition in one embodiment of this application.

[0088] Figure 12 is a cross-sectional view of the process of forming a first doped layer and a second doped layer at least on the side of the tunneling passivation layer away from the substrate based on physical vapor deposition in another embodiment of this application.

[0089] Figure 13 is a cross-sectional view of the process of forming a first interface oxide layer on the side of the first doped amorphous silicon layer away from the tunneling passivation layer in another embodiment of this application.

[0090] Figure 14 is a schematic diagram of the structure of a photovoltaic module in one embodiment of this application.

[0091] Explanation of reference numerals in the attached figures: 100 - Solar cell; 110 - Substrate; 120 - Tunneling passivation layer; 131 - First doped layer; 132 - Second doped layer; 101 - Gallium-doped hybrid material target; 102 - Boron-doped hybrid material target; 103 - Initial target; 1301 - First doped amorphous silicon layer; 1302 - Second doped amorphous silicon layer; 1303 - Interface amorphous silicon layer; 140 - First interface oxide layer; 150 - Second interface oxide layer; 160 - Interface polycrystalline silicon layer; 181 - First passivation antireflection layer; 171 - First polycrystalline silicon conductive layer; 182 - Second passivation antireflection layer; 172 - Second polycrystalline silicon conductive layer; 183 - Conductive passivation layer; 173 - Third polycrystalline silicon conductive layer; 184 - Third passivation antireflection layer; 185 - Fourth passivation antireflection layer; 122 - Tunneling oxide layer; 133 - Third doped layer; 186 - Fifth passivation and antireflection layer; 187 - Sixth passivation and antireflection layer; F1 - First region; F2 - Second region; F3 - Third region; F4 - Fourth region; 191 - First electrode; 192 - Second electrode; 200 - Photovoltaic module; 210 - Cell string. Detailed Implementation

[0092] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0093] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0094] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0095] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0096] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0097] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0098] The following description, in conjunction with the accompanying drawings, illustrates the solar cells, their manufacturing methods, and photovoltaic modules according to embodiments of this application.

[0099] The solar cell provided in this application embodiment can be any type of solar cell such as TOPCon, BC, POLO, or TOPCore.

[0100] Referring to Figures 1-3B, in one embodiment of this application, the solar cell may include a substrate 110, a tunneling passivation layer 120, a first doped layer 131, a second doped layer 132, and at least one first electrode 191.

[0101] The substrate 110 includes a first surface and a second surface disposed opposite to each other along the thickness direction of the substrate 110. One of the first surface and the second surface is a light-receiving surface, and the other is a back-lighting surface. It is understood that the substrate 110 has opposing back-lighting and light-receiving surfaces along its thickness direction. The light-receiving surface can be understood as the surface of the solar cell facing sunlight, and the back-lighting surface can be understood as the surface of the solar cell facing away from sunlight. The substrate 110 is used to receive incident light and generate photogenerated carriers. The substrate 110 includes, but is not limited to, doped semiconductor substrates with silicon or germanium as the base material, or doped compound semiconductor substrates such as silicon carbide, silicon germanium, gallium arsenide, indium phosphide, zinc oxide, or gallium oxide. Exemplarily, in the embodiments of this application, the material of the substrate 110 may be doped single-crystal silicon. Further, the doping element type of the substrate 110 can be N-type, and the N-type element can be, for example, any one of phosphorus, arsenic, or antimony; the doping element type of the substrate 110 can also be P-type, and the P-type element can be, for example, boron or gallium. For example, the doping type of the substrate 110 is N-type. In this application, the light-receiving surface and the back-light-receiving surface of the substrate 110 will also have certain morphological changes based on the morphology of features such as the battery film layer.

[0102] A tunneling passivation layer 120, a first doped layer 131, and a second doped layer 132 are stacked on the first surface of the substrate 110. It is understood that the tunneling passivation layer 120 can be located on the back surface of the substrate or on the light-receiving surface of the substrate 110. The tunneling passivation layer 120 can be located on a portion or the entire first surface of the substrate 110. The material of the tunneling passivation layer 120 can be a tunneling oxide, such as silicon oxide, silicon oxynitride, aluminum oxide, titanium oxide, or silicon oxide doped with N-type elements. Optionally, the material of the tunneling passivation layer 120 may also include at least one of magnesium fluoride, amorphous silicon, polycrystalline silicon, silicon carbide, and silicon nitride. For example, the material of the tunneling passivation layer 120 includes SiOx. In an exemplary embodiment, the thickness of the tunneling passivation layer 120 ranges from 0.5 nm to 3 nm. The tunneling passivation layer 120 is used to achieve interface passivation of the substrate 110, providing a chemical passivation effect. Specifically, by using dangling bonds on the surface of the saturated substrate 110, the density of interface defect states of the substrate 110 is reduced, thereby reducing the recombination centers of the substrate 110 and lowering the carrier recombination rate, which in turn increases the open-circuit voltage of the solar cell and improves the photoelectric conversion efficiency of the solar cell.

[0103] The first doped layer 131 is located between the tunneling passivation layer 120 and the second doped layer 132. It is understood that the first doped layer 131 may be located on the surface of the tunneling passivation layer 120 away from the substrate 110. The materials of the first doped layer 131 and the second doped layer 132 may respectively include doped polysilicon, or doped polysilicon containing at least one element selected from oxygen, carbon, and nitrogen. Furthermore, the doping type of both the first doped layer 131 and the second doped layer 132 is p-type. In the embodiments of this application, the doping elements of the first doped layer 131 and the second doped layer 132 are not completely identical. For example, the first doped layer 131 includes at least gallium, and the second doped layer 132 includes at least boron. In some embodiments, the first doped layer 131 and the second doped layer 132 may each include a primary doping element. Optionally, the second doped layer 132 may also include a secondary doping element. The primary doping elements of the first doped layer 131 and the second doped layer 132 are different. For example, the primary doping element of the first doped layer 131 is gallium, and the primary doping element of the second doped layer 132 is boron. Optionally, the auxiliary doping element of the second doped layer 132 may be the same as the main doping element of the first doped layer 131. The main doping element refers to the element with a relatively high concentration when multiple doping elements exist in the same layer; the auxiliary doping element refers to the element with a relatively low concentration when multiple doping elements exist in the same layer.

[0104] In this embodiment, the solar cell includes a substrate 110, a tunneling passivation layer 120, a first doped layer 131, and a second doped layer 132, which can be used to achieve interface passivation of the tunneling passivation layer 120, achieving the effect of field-effect passivation. An electric field can be generated at the interface to prevent carriers of similar polarity from approaching each other due to the repulsion effect, thereby greatly reducing the recombination of photogenerated carriers. In some embodiments, the first doped layer 131 is a predominantly gallium-doped polycrystalline silicon layer, and the second doped layer 132 is a predominantly boron-doped polycrystalline silicon layer. Because boron has a low segregation coefficient at the interface of the tunneling passivation layer 120 (e.g., SiOx), it reduces the passivation performance between p+ poly-Si (doped polycrystalline silicon) and the tunneling passivation layer 120. Simultaneously, because the solid solubility of gallium (Ga) in silicon is an order of magnitude lower than that of boron (B), the effective doping concentration activated by annealing is low, making it difficult to obtain a low contact resistivity. By placing the gallium-doped first doped layer 131 adjacent to the tunneling passivation layer 120, the contact between the boron-doped second doped layer 132 and the tunneling passivation layer 120 can be avoided, thereby improving passivation performance. Furthermore, gallium atoms are larger than boron atoms, and their size is close to that of phosphorus (P) atoms. At the same annealing temperature, they can achieve similar inward expansion effects, ensuring the solid solubility of gallium in silicon. This not only further enhances the passivation effect between the first doped layer 131 and the tunneling passivation layer 120 but also reduces contact resistivity.

[0105] Furthermore, in the embodiments of this application, both the first doped layer 131 and the second doped layer 132 are prepared using physical vapor deposition (PVD) technology. Exemplarily, the physical vapor deposition may include one of vacuum evaporation (e.g., thermal evaporation such as resistance heating, high-frequency induction heating, electron beam, laser beam, and ion beam evaporation), magnetron sputtering, reactive plasma deposition (RPD), and arc plasma deposition. In some embodiments, the specific physical vapor deposition method used for the first doped layer 131 and the second doped layer 132 is the same. Exemplarily, the first doped layer 131 and the second doped layer 132 can be formed continuously using the same physical vapor deposition method. By using the same physical vapor deposition method to form the first doped layer 131 and the second doped layer 132, compared to related technologies that use processes such as ion implantation and solution methods to prepare single-layer doped layers instead of forming a stacked passivation film layer including the first and second doped layers, the solar cell provided in the embodiments of this application can significantly reduce process costs.

[0106] In an exemplary embodiment, the first doped layer 131 is doped with gallium and the second doped layer 132 is doped with boron.

[0107] Optionally, the doping elements of the first doped layer 131 may include boron and gallium, with gallium being the primary doping element. For example, the doping concentration of gallium may be higher than that of boron.

[0108] Optionally, the doping elements of the second doped layer 132 may include boron and gallium, with boron being the primary doping element. For example, the doping concentration of boron is higher than that of gallium.

[0109] In this embodiment, the second doped layer 132 is doped with both boron elements, which can not only reduce the impact of light attenuation on the performance of polysilicon, but also make the resistance range of the second doped layer 132 narrower and more uniform.

[0110] The first doped layer 131 and the second doped layer 132 together constitute a P-type passivation stack 130 disposed on the tunneling passivation layer 120.

[0111] The first electrode 191 is in contact with the second doped layer 132. When the solar cell includes multiple second doped layers 132, the electrode is in contact with the outermost second doped layer 132. In some embodiments, the first electrode 191 is in contact only with the second doped layer 132, and is spaced apart from the first doped layer 131.

[0112] In an exemplary embodiment, referring to FIG4, the solar cell includes at least two first doped layers 131 and at least two second doped layers 132, wherein, in the thickness direction (or a first direction), each first doped layer 131 and each second doped layer 132 is alternately stacked on the side of the tunneling passivation layer 120 away from the substrate 110. The first direction is the direction from the substrate 110 toward the first doped layer 131.

[0113] In this embodiment of the application, for ease of explanation, a solar cell comprising three first doped layers 131 and three second doped layers 132 is used as an example for description. The first doped layer 131-1, the second doped layer 132-1, the first doped layer 131-2, the second doped layer 132-2, the first doped layer 131-3, and the second doped layer 132-3 are sequentially stacked on a portion or the entire surface of the first surface of the substrate.

[0114] In some embodiments, the concentration of gallium in each of the first doped layers 131 gradually decreases in the second direction. It is understood that the gallium dopant in each of the first doped layers 131 diffuses along the second direction. The second direction is opposite to the first direction, and may be a direction pointing from the second doped layer 132 to the tunneling passivation layer 120.

[0115] In one exemplary embodiment, the maximum concentration of gallium in each of the first doped layers 131 ranges from 8E19cm⁻¹. -3 -12E19 / cm -3 For example, at the interface of the tunneling passivation layer 120 (e.g., SiOx), the concentration of gallium dopant in the first doped layer 131 is approximately 1-5E19 cm⁻¹. -3 .

[0116] In the second direction, the concentration of boron in each of the second doped layers 132 gradually decreases. It can be understood that the boron dopant in each of the second doped layers 132 diffuses along the second direction. In an exemplary embodiment, the maximum concentration of boron in each of the second doped layers 132 ranges from 5E19cm⁻¹. -3 -11E19 / cm -3 Since excessively high boron doping concentrations can impair the passivation effect of the ultrathin tunneling passivation layer 120, in this embodiment, the boron doping concentration in the P-type passivation stack 130 is below 1E17cm⁻¹. -3 In this way, the boron element in the second doped layer 132 can be prevented from diffusing to the SiOx interface of the tunneling passivation layer 120, so as to avoid damaging the passivation effect of the tunneling passivation layer 120.

[0117] In some embodiments, the thickness of the first doped layer 131 ranges from 10 nm to 150 nm. For example, the thickness of the first doped layer 131 can be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, or 150 nm. In some embodiments, the thickness of the second doped layer 132 ranges from 5 nm to 150 nm. For example, the thickness of the second doped layer 132 can be 5 nm, 8 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, or 150 nm. This is beneficial for the P-type passivation stack 130 to possess superior passivation performance.

[0118] In this embodiment, the solar cell includes a plurality of first doped layers 131 and a plurality of second doped layers 132 alternately located on the tunneling passivation layer 120. The gallium doping concentration in the first doped layer 131 gradually increases in a first direction; the boron doping concentration in the second doped layer 132 also gradually increases in the first direction, such that the doped elements in the first doped layer 131 and the second doped layer 132 closest to the tunneling passivation layer 120 have the lowest doping concentration. For example, the gallium doping concentration in the first doped layer 131-1 is less than that in the first doped layer 131-2, and the gallium doping concentration in the first doped layer 131-2 is less than that in the first doped layer 131-3; the boron doping concentration in the second doped layer 132-1 is less than that in the second doped layer 132-2, and the boron doping concentration in the second doped layer 132-2 is less than that in the second doped layer 132-3. A low doping concentration can reduce the interface state density and band gap between the p-type passivation stack 130 and the tunneling passivation layer 120, thereby increasing or decreasing contact and passivation effects, improving carrier transport, and ultimately improving the photoelectric conversion efficiency of the solar cell. In some embodiments, gallium in each first doped layer 131 may have a gradually decreasing concentration along the second direction or a uniform concentration; boron in each second doped layer 132 may have a gradually decreasing concentration along the second direction or a uniform concentration.

[0119] In an exemplary embodiment, referring to Figures 1-3B, the solar cell further includes at least one first interface oxide layer 140. The first interface oxide layer 140 is located between the first doped layer 131 and the second doped layer 132. In this embodiment, a first doped layer 131 and a second doped layer 132 are collectively understood as a P-type passivation structure unit. The number of first interface oxide layers 140 is less than or equal to the number of P-type passivation structure units. For example, the solar cell includes m P-type passivation structure units, wherein a first interface oxide layer 140 may be provided between the first doped layer 131 and the second doped layer 132 in each P-type passivation structure unit. Alternatively, a first interface oxide layer 140 may be provided between the first doped layer 131 and the second doped layer 132 in the bottommost P-type passivation structure unit (i.e., the P-type passivation structure unit closest to the tunneling passivation layer 120), while no first interface oxide layer 140 is provided in the other P-type passivation structure units. Alternatively, among the m P-type passivation structural units, some P-type passivation structural units are provided with a first interface oxide layer 140, while some P-type passivation structural units are not provided with a first interface oxide layer 140.

[0120] The material of the first interface oxide layer 140 can be a dielectric material, such as at least one of silicon oxide, magnesium fluoride, amorphous silicon, polycrystalline silicon, silicon carbide, silicon nitride, silicon oxynitride, aluminum oxide, or titanium oxide. In this embodiment, the material of the first interface oxide layer 140 can be silicon oxide. Generally, the boron element in the second doped layer 132 can diffuse along the second direction into the tunneling passivation layer 120. After passing through the first interface oxide layer 140, the boron doping concentration decreases by 2-4E19cm⁻¹. -3 By appropriately setting the boron doping concentration, the boron doping concentration at the interface between the tunneling passivation layer 120 and the first doped layer 131 can be kept below 1E17cm. -3 This can prevent excessively high concentrations of boron from damaging the passivation effect of the ultrathin tunneling passivation layer 120.

[0121] In one exemplary embodiment, the thickness of the first interface oxide layer 140 is 0.5 nm to 2 nm. For example, the thickness of the first interface oxide layer 140 may be 0.5 nm, 0.8 nm, 1 nm, 1.5 nm, 1.8 nm, or 2 nm.

[0122] By setting a first interface oxide layer 140 between the first doped layer 131 and the second doped layer 132, the diffusion rate of boron can be reduced, so as to avoid excessively high concentrations of boron from damaging the passivation effect of the ultrathin tunneling passivation layer 120, and the passivation performance between the first doped layer 131 and the second doped layer 132 can also be improved.

[0123] Referring to Figure 5, in an exemplary embodiment, the solar cell may further include at least one second interface oxide layer 150. In the thickness direction, the second interface oxide layer 150 is located on the side of the second doped layer away from the first doped layer. It is understood that each second interface oxide layer 150 is located between two adjacent P-type passivation structural units. The material of the second interface oxide layer 150 may include, but is not limited to, at least one of silicon oxide, magnesium fluoride, silicon oxide, amorphous silicon, polycrystalline silicon, silicon carbide, silicon nitride, silicon oxynitride, aluminum oxide, or titanium oxide. In this embodiment, the material of the second interface oxide layer 150 may be silicon oxide. The thickness of the second interface oxide layer 150 is 0.5 nm to 2 nm. For example, the thickness of the second interface oxide layer 150 may be 0.5 nm, 0.7 nm, 1 nm, 1.2 nm, 1.5 nm, 1.8 nm, or 2 nm.

[0124] In this embodiment, by providing a second interface oxide layer 150 between two P-type passivation structural units, the solar cell can have better passivation performance.

[0125] Referring to Figure 6, in an exemplary embodiment, the solar cell further includes an interface polycrystalline silicon layer 160 located between the tunneling passivation layer 120 and the first doped layer 131. The interface polycrystalline silicon layer 160 may be made of polycrystalline silicon. Optionally, the doping element of the interface polycrystalline silicon layer 160 may include at least one element selected from oxygen, carbon, and nitrogen. The thickness of the interface polycrystalline silicon layer 160 is from 3 nanometers to 150 nanometers.

[0126] In some embodiments, the solar cell may include the first interface oxide layer 140, the second interface oxide layer 150 and the interface polycrystalline silicon layer 160 simultaneously, or it may include only one or two of the first interface oxide layer 140, the second interface oxide layer 150 and the interface polycrystalline silicon layer 160.

[0127] Referring to Figure 1, in some embodiments, the first surface is the backlight surface and the second surface is the light-receiving surface, wherein the tunneling passivation layer 120, the first doped layer 131, and the second doped layer 132 in the aforementioned embodiments are located on the backlight surface side. Further, the solar cell may also include one or more of the following: a first passivation antireflection layer 181, a first polycrystalline silicon conductive layer 171, a second passivation antireflection layer 182, a second polycrystalline silicon conductive layer 172, a conductive passivation layer 183, and a second electrode 192. The first passivation antireflection layer 181 is located on the side of the second doped layer 132 away from the first doped layer 131. The first polycrystalline silicon conductive layer 171, the second passivation antireflection layer 182, the second polycrystalline silicon conductive layer 172, and the conductive passivation layer 183 are sequentially stacked on the second surface of the substrate 110. The first polycrystalline silicon conductive layer 182 and the second polycrystalline silicon conductive layer 172 are both N-type doped. The second electrode 192 is disposed on one side of the second surface of the substrate 110 and is in contact with the conductive passivation layer 183. The first electrode 191 is disposed on one side of the first surface of the substrate 110 and is in contact with the second doped layer 132.

[0128] Referring to Figure 2, in some embodiments, the first surface is the backlight surface and the second surface is the light-receiving surface. The tunneling passivation layer 120, the first doped layer 131, and the second doped layer 132 in the aforementioned embodiments are located on the backlight side. Further, the solar cell may also include one or more of the following: at least a third polycrystalline silicon conductive layer 173, at least a third passivation antireflection layer 184, at least a fourth passivation antireflection layer 185, and a second electrode 191. The second surface of the substrate 110 includes a first region F1 and a second region F2. The first region F1 is correspondingly disposed with respect to the second electrode 192; for example, the first region F1 is an electrode region, and the second region F2 can be understood as a non-electrode region.

[0129] At least one third polysilicon conductive layer 173 is stacked in the first region F1. Exemplarily, in this embodiment, the dopant element of the third polysilicon conductive layer 173 is phosphorus (P) or other N-type elements. The number of third polysilicon conductive layers 173 can be one, or more than two. The material or dopant material of each third polysilicon conductive layer 173 can be the same or different.

[0130] At least one third passivation antireflection layer 184 is stacked in the second region F2. For example, the number of third passivation antireflection layers can be one, or more than two. The material of each third passivation antireflection layer can be the same or different.

[0131] At least one fourth passivation antireflection layer 185 is stacked on the side of the second doped layer 132 away from the first doped layer 131. For example, the number of fourth passivation antireflection layers 185 can be one, or more than two. The material of each fourth passivation antireflection layer 185 can be the same or different.

[0132] The materials of the third passivation antireflection layer 184 and the fourth passivation antireflection layer 185 can be independently selected from one or more of alumina, silicon nitride, and silicon oxynitride.

[0133] The second electrode 192 is disposed on one side of the second surface of the substrate 110 and is in contact with the third polysilicon conductive layer 173. The first electrode 191 is disposed on one side of the first surface of the substrate and is in contact with the second doped layer 132.

[0134] Referring to Figures 3A and 3B, in some embodiments, the first surface is the light-receiving surface, and the second surface is the backlighting surface. In the aforementioned embodiments, the tunneling passivation layer 120, the first doped layer 131, and the second doped layer 132 are located on the side of the light-receiving surface. Further, the solar cell may also include one or more of the following: a tunneling oxide layer 122, a third doped layer 133, a fifth passivation antireflection layer 186, a sixth passivation antireflection layer 187, and a second electrode 192.

[0135] In this embodiment, the first surface of the substrate 110 includes a third region F3 and a fourth region F4. The tunneling passivation layer 122 is located locally on the first surface; for example, the tunneling passivation layer 122 may only be located in the third region F3 of the first surface. A sixth passivation antireflection layer 187 is located on the side of the second doped layer 132 away from the first doped layer 131 and in the fourth region F4 of the first surface. The tunneling oxide layer 122, the third doped layer 133, and the fifth passivation antireflection layer 186 are stacked on the second surface of the substrate 110. The doping type of the third doped layer 133 is different from that of the first doped layer 131; for example, the doping type of the third doped layer 133 is N-type, and it may be a phosphorus-doped polycrystalline silicon layer. A first electrode 191 is disposed on one side of the first surface of the substrate 110 and in contact with the second doped layer 132, and a second electrode 192 is disposed on one side of the second surface of the substrate 110 and in contact with the third doped layer 133. The material of the tunneling oxide layer 122 may be silicon oxide.

[0136] It should be noted that the solar cells provided in this application are not limited to the solar cells shown in Figures 1-3B, but can also be solar cells of other structural types.

[0137] This embodiment provides a method for manufacturing a solar cell, which is used to produce the solar cell in any of the above embodiments. The structure, function, and working principle of the solar cell have been described in detail in the above embodiments and will not be repeated here. As shown in Figure 7, the method for manufacturing a solar cell includes steps 702-706.

[0138] Step 702, providing a substrate, the substrate including a first surface and a second surface disposed opposite to each other along the substrate thickness direction.

[0139] Please continue referring to Figures 1-3. In this embodiment, the substrate 110 is an N-type silicon substrate as an example for explanation. After providing the N-type silicon substrate, the surface cutting damage layer can be removed by alkaline polishing, and the N-type silicon substrate can be pre-cleaned to remove impurities on the surface of the N-type silicon substrate. Optionally, the method for fabricating a solar cell provided in this embodiment further includes texturing a portion of the surface of the substrate 110 to form a textured surface. In addition, a cleaning solution (e.g., RCA-1 and RCA-2) can be used to clean the organic matter and metal ions on the textured surface. This can reduce reflectivity and increase the absorption of sunlight by the silicon substrate 110.

[0140] Step 704: A tunneling passivation layer is formed on the first surface of the substrate.

[0141] For example, a tunneling passivation layer 120 can be formed on one side of the substrate 110 using plasma-enhanced chemical vapor deposition (PECVD). For instance, the substrate 110 (e.g., a silicon wafer) can be placed in a plate-type PECVD apparatus to deposit the tunneling passivation layer 120. For example, N₂O and Ar can be used as process gases to react with the surface of an N-type silicon substrate, forming a SiOx layer as the tunneling passivation layer 120 at a temperature of 400-500°C.

[0142] Step 706: Based on physical vapor deposition, a first doped layer and a second doped layer are stacked at least on the side of the tunneling passivation layer away from the substrate to form a first doped layer and a second doped layer.

[0143] Physical vapor deposition (PVD) refers to the deposition of the evaporated material and its reaction products onto the tunneling passivation layer 120 under vacuum conditions using a low-voltage, high-current arc discharge technique. The gas discharge evaporates the target material, ionizing both the evaporated material and the gas. The electric field then accelerates the deposition, causing the evaporated material and its reaction products to deposit onto the passivation layer 120. In this application, PVD includes, but is not limited to, vacuum evaporation (e.g., thermal evaporation such as resistance heating, high-frequency induction heating, electron beam, laser beam, and ion beam evaporation), magnetron sputtering, reactive plasma deposition (RPD), and arc plasma deposition. In this embodiment, both the first doped layer 131 and the second doped layer 132 are p-type doped elements, but the primary doping elements differ. For example, the primary doping element of the first doped layer 131 is gallium, and the primary doping element of the second doped layer 132 is boron.

[0144] In this embodiment, the method for fabricating a solar cell may include providing a substrate 110, forming a tunneling passivation layer 120 on one side of the substrate 110, and forming at least one passivation stack 130 on the side of the tunneling passivation layer 120 away from the substrate 110 based on physical vapor deposition. For example, based on physical vapor deposition, a first doped layer 131 and a second doped layer 132 may be stacked at least on the side of the tunneling passivation layer 120 away from the substrate 110. Thus, the first doped layer 131 and the second doped layer 132 can be continuously formed using physical vapor deposition. Compared to related technologies that use ion implantation, solution methods, or other processes to fabricate a single-layer doped layer instead of forming a stacked passivation film including a first doped layer and a second doped layer, the physical vapor deposition technology provided in this embodiment is closer to mass production conditions. It can achieve large-area, high-yield, stable, and controllable processes, simplifying the process steps for forming the first doped layer 131 and the second doped layer 132 and significantly reducing process costs.

[0145] In some embodiments, the first doped layer 131 is a gallium-doped polysilicon layer, and the second doped layer 132 is a boron-doped polysilicon layer. Since boron has a low segregation coefficient at the tunneling passivation layer 120 (e.g., SiOx), it reduces the passivation performance between p+ poly-Si (doped polysilicon) and the tunneling passivation layer 120. Simultaneously, because gallium (Ga) has a solid solubility in silicon that is an order of magnitude lower than boron (B), the effective doping concentration after annealing activation is low, making it difficult to obtain a low contact resistivity. By placing the gallium-doped first doped layer 131 adjacent to the tunneling passivation layer 120, the contact between the boron-doped second doped layer 132 and the tunneling passivation layer 120 can be avoided, thereby improving the passivation performance. In addition, gallium atoms are larger than boron atoms and are close to phosphorus (P) atoms. At the same annealing temperature, they can achieve similar internal expansion effects, ensuring the solid solubility of gallium in silicon. This not only further improves the passivation effect between the first doped layer 131 and the tunneling passivation layer 120, but also reduces the contact resistivity.

[0146] In an exemplary embodiment, as shown in FIG8, a first doped layer and a second doped layer are formed at least on the side of the tunneling passivation layer away from the substrate based on physical vapor deposition, including steps 802-806.

[0147] Step 802, provide the target unit.

[0148] The target unit includes a gallium-doped hybrid material target and a boron-doped hybrid material target. Referring to Figures 9 and 10, the gallium-doped hybrid material target 101 and the boron-doped hybrid material target 102 can be arranged in the deposition sequence. The gallium-doped hybrid material target 101 can be a target comprising a hybrid material, which may include silicon and gallium elements, and is a gallium-doped silicon-based target. The boron-doped hybrid material target 102 can be a target comprising a hybrid material, which may include silicon and boron elements, and is a boron-doped silicon-based target.

[0149] The shape of the hybrid material target may include, but is not limited to, rectangular, circular, elliptical, etc. The number of gallium-doped hybrid material target 101 and boron-doped hybrid material target 102 may be one or more. It should be noted that the shape and number of hybrid targets are not specifically limited in this embodiment.

[0150] Each gallium-doped hybrid material target 101 and each boron-doped hybrid material target 102 are arranged in a deposition sequence. The deposition sequence can be the deposition sequence of each doped layer during the formation of the first doped layer 131 and the second doped layer 132. For example, in the embodiments of this application, the amorphous silicon film layer corresponding to the first doped layer 131 is formed before the amorphous silicon film layer corresponding to the second doped layer 132.

[0151] For clarity, please refer to Figure 9, using two gallium-doped mixed material targets 101 and two boron-doped mixed material targets 102 as examples. The two gallium-doped mixed material targets 101 are arranged consecutively to form the first doped layer 131; the two boron-doped mixed material targets 102 are arranged consecutively to form the second doped layer 132. The two gallium-doped mixed material targets 101 and the two boron-doped mixed material targets 102 are arranged along a third direction. The third direction can be understood as the bombardment sequence of the targets during physical vapor deposition. It can be understood that the two gallium-doped mixed material targets 101 and the two boron-doped mixed material targets 102 constitute a target unit. In the embodiments of this application, at least one target unit can be provided, and each target unit may include at least one gallium-doped mixed material target 101 and at least one boron-doped mixed material target 102.

[0152] Optionally, embodiments of this application may also provide multiple target units to form multiple passivation stacks 130. The number and shape of the mixed targets in each target unit may be the same or different, and no specific limitations are made in these embodiments.

[0153] Step 804: Based on the target unit, a first doped amorphous silicon layer and a second doped amorphous silicon layer are formed on the side of the tunneling passivation layer away from the substrate by physical vapor deposition.

[0154] Please refer to Figure 11. The doping elements of the first doped amorphous silicon layer 1301 include at least gallium, and the doping elements of the second doped amorphous silicon layer 1302 include at least boron.

[0155] In the embodiments of this application, physical vapor deposition includes, but is not limited to, vacuum evaporation (e.g., thermal evaporation such as resistance heating, high-frequency induction heating, and electron beam, laser beam, and ion beam evaporation), magnetron sputtering, reactive plasma deposition (RPD), and arc plasma deposition.

[0156] For ease of explanation, this embodiment uses physical vapor deposition, including magnetron sputtering and electron beam evaporation, as examples. Exemplarily, step 804 may specifically include forming a first doped amorphous silicon layer 1301 (e.g., gallium-doped amorphous silicon layer) and a second doped amorphous silicon layer 1302 (e.g., boron-doped amorphous silicon layer) on the side of the tunneling passivation layer 120 away from the substrate 110 using magnetron sputtering based on the mixed gas and each mixed material target. Optionally, step 704 may specifically include bombarding each mixed material target in the target unit with a high-energy electron beam in the deposition sequence to deposit the first doped amorphous silicon layer 1301 and the second doped amorphous silicon layer 1302 on the side of the tunneling passivation layer away from the substrate.

[0157] Step 806: Perform annealing.

[0158] Please continue referring to Figure 11. The structure obtained in step 804 is subjected to annealing treatment, at least on the side of the tunneling passivation layer 120 away from the substrate 110, to form a first doped layer 131 and a second doped layer 132. For example, the structure obtained in step 704 can be placed in a tube annealing furnace for annealing treatment. Its first doped amorphous silicon layer 1301 (e.g., gallium-doped amorphous silicon layer) can be converted into a gallium-doped polycrystalline silicon layer, i.e., the first doped layer 131; its second doped amorphous silicon layer 1302 (e.g., boron-doped amorphous silicon layer) can be converted into a boron-doped polycrystalline silicon layer, i.e., the second doped layer 132. For example, the annealing temperature can be 880℃-1050℃, for example, 880℃, 895℃, 910℃, 925℃, 940℃, 955℃, 970℃, 985℃, 1000℃, or 1050℃. It should be noted that the annealing temperature is not limited to the examples mentioned above, and can also be other temperatures.

[0159] In some embodiments, the first doped layer 131 and the second doped layer 132 can be formed using magnetron sputtering in physical vapor deposition. The mixed gas used in magnetron sputtering may include a sputtering gas and a doping gas. The sputtering gas may include argon, and the doping gas may include a gallium source precursor and a boron source precursor. Exemplarily, the gallium source precursor includes, but is not limited to, trimethylgallium (TMGa), thus enabling off-source doping (dissociation of the Ga target and the trimethylgallium source precursor) and increasing the doping concentration. Exemplarily, the boron source precursor includes, but is not limited to, at least one of diboron hexahydrogenate (B₂H₆) and trimethyl borate (TMB), thus enabling off-source doping (dissociation of the B target and the boron source precursor) and increasing the doping concentration.

[0160] For example, using argon as the sputtering gas and a gallium source precursor as the doping gas, a gallium-doped amorphous silicon layer 1301 is formed by bombarding a gallium-doped hybrid material target 101. Subsequently, based on the gallium-doped amorphous silicon layer 1301, using argon as the sputtering gas and a boron source precursor as the doping gas, a boron-doped hybrid material target 102 is formed by bombarding it, thereby forming a doped amorphous silicon stack including the gallium-doped amorphous silicon layer 1301 and the boron-doped amorphous silicon layer 1302.

[0161] In some embodiments, the thickness of the gallium-doped amorphous silicon layer 1301 can be 5nm-100nm. For example, the thickness of the gallium-doped amorphous silicon layer 1301 can be 5nm, 10nm, 15nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, or 100nm. The thickness of the boron-doped amorphous silicon layer 1302 can be 10nm-200nm. For example, the thickness of the boron-doped amorphous silicon layer 1302 can be 10nm, 15nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, or 100nm.

[0162] In this embodiment, a gallium-doped amorphous silicon layer 1301 and a boron-doped amorphous silicon layer 1302 are formed on the tunneling passivation layer 120 using magnetron sputtering technology. The resulting structure is then annealed to form a first doped layer 131 and a second doped layer 132. This magnetron sputtering technology is closer to mass production conditions, enabling large-area, high-yield, stable, and controllable processes. It also simplifies the process steps for forming the first doped layer 131 and the second doped layer 132, significantly reducing process costs. Furthermore, by using a gallium-doped hybrid target 101 and a boron-doped hybrid target 102, and by using gallium and boron source precursors, the stability and uniformity of magnetron sputtering can be improved, thereby increasing the yield of solar cells.

[0163] In some embodiments, the gallium-doped hybrid material target 101 comprises a mixture of silicon and gallium, with a molar ratio of gallium to silicon of 1 / 2000 to 1 / 25. Exemplarily, the molar ratio of gallium to silicon can be 1 / 2000, 1 / 1000, 1 / 500, 1 / 250, 1 / 125, 1 / 75, 1 / 50, or 1 / 25. The boron-doped hybrid material target 102 comprises a mixture of silicon and boron, with a molar ratio of boron to silicon of 1 / 2000 to 1 / 25. Exemplarily, the molar ratio of boron to silicon can be 1 / 2000, 1 / 1000, 1 / 500, 1 / 250, 1 / 125, 1 / 75, 1 / 50, or 1 / 25. It should be noted that the values ​​of the ratios of gallium and boron to silicon are not limited to the examples described above and can also be other numerical values.

[0164] In the embodiments of this application, by setting the ratio of gallium to silicon in the gallium-doped hybrid material target and the ratio of boron to silicon in the boron-doped hybrid material target, both interfacial recombination and contact resistivity can be reduced, thereby improving the stability of the solar cell and increasing the yield of the solar cell.

[0165] In some embodiments, the doping gas includes a gallium source precursor and a boron source precursor. The doping percentage of the gallium source precursor is 0.1%-10%, and the doping percentage of the boron source precursor is 0.1%-10%. For example, the doping percentages of the gallium source precursor and the boron source precursor can be 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, and 10%, respectively. It should be noted that the values ​​of the doping percentages of the gallium source precursor and the boron source precursor are not limited to the examples given above, and can also be other percentages. By adjusting the doping percentages of the gallium source precursor and the boron source precursor, their doping concentration can be increased, thereby reducing interfacial recombination and contact resistivity.

[0166] Optionally, in addition to gallium and boron source precursors, the doping gas may also include at least one of methane, carbon dioxide, and ammonia. During magnetron sputtering, the passivation and optical properties of the doped polycrystalline silicon layer can be adjusted by introducing appropriate amounts of doping gases such as methane, carbon dioxide, and ammonia. For example, the doping percentage of methane is 10%-50%, such as 10%, 20%, 30%, 40%, and 50%; the doping percentage of ammonia is 0.5%-30%, such as 0.5%, 10%, 20%, and 30%; and the doping percentage of carbon dioxide is 0.1%-50%, such as 0.1%, 10%, 20%, 30%, 40%, and 50%. It should be noted that the doping percentages of methane, carbon dioxide, and ammonia can be any values ​​within their respective ranges. By setting the doping percentages of methane, carbon dioxide, and ammonia, the passivation and optical properties of the doped polycrystalline silicon layer can be further optimized.

[0167] In some embodiments, a heating device may be provided within the PVD process chamber to control the temperature of the substrate 110 on the carrier plate. Exemplarily, the heating device can maintain the temperature of the substrate 110 between 200°C and 450°C. For example, the temperature of the substrate 110 can be 200°C, 250°C, 275°C, 300°C, 325°C, 350°C, 375°C, 400°C, 420°C, or 450°C. It should be noted that the temperature of the substrate 110 is not limited to the examples described above, and can be any value between 200°C and 450°C. Thus, by controlling the temperature of the substrate 110 and maintaining it between 200°C and 450°C, the stability and uniformity of the gallium-doped amorphous silicon layer 1301 and the boron-doped amorphous silicon layer 1302 formed by magnetron sputtering can be further improved, thereby increasing the yield of solar cell fabrication.

[0168] In some embodiments, unlike the foregoing embodiments, the physical vapor deposition provided in this embodiment is electron beam evaporation in vacuum evaporation. In this embodiment, electron beam evaporation is used as an example to illustrate the fabrication method of the solar cell. Step 804 may specifically include bombarding each mixed material target in the target unit with a high-energy electron beam in the order of deposition, depositing a first doped amorphous silicon layer 1301 and a second doped amorphous silicon layer 1302 on the side of the tunneling passivation layer 120 away from the substrate 110. For example, the gallium-doped mixed material target 101 is bombarded with a first high-energy electron beam to evaporate gallium, which is deposited on the side of the tunneling passivation layer 120 away from the substrate, thereby forming a gallium-doped amorphous silicon layer 1301. For example, the deposition rate of the gallium-doped amorphous silicon layer 1301 is 0.1 nm / min-5 nm / min, and the thickness of the formed gallium-doped amorphous silicon layer 1301 is 5 nm-100 nm. Boron-doped hybrid material target 102 is bombarded by a second high-energy electron beam, causing boron to evaporate and deposit on the side of tunneling passivation layer 120 away from the substrate, thereby forming boron-doped amorphous silicon layer 1302. For example, the deposition rate of boron-doped amorphous silicon layer 1302 is 0.1 nm / min-5 nm / min, and the thickness of the formed boron-doped amorphous silicon layer 1302 is 10 nm-200 nm.

[0169] Optionally, a heating device may be provided within the electron beam process chamber to control the temperature of the substrate 110 on the carrier plate. For example, the heating device can maintain the temperature of the substrate 110 between 200°C and 450°C. Thus, by controlling the temperature of the substrate 110 and keeping it between 200°C and 450°C, the stability and uniformity of the gallium-doped amorphous silicon layer 1301 and the boron-doped amorphous silicon layer 1302 formed by electron beam evaporation can be further improved, thereby increasing the yield of solar cell fabrication.

[0170] In this embodiment, gallium-doped amorphous silicon layer 1301 and boron-doped amorphous silicon layer 1302 are formed by electron beam evaporation on the tunneling passivation layer, and then the first doped layer 131 and the second doped layer 132 are formed by annealing. The electron beam evaporation can be closer to the conditions of mass production, and it can achieve large area, high capacity, stable and controllable process. It can also simplify the process steps of forming the first doped layer 131 and the second doped layer 132, significantly reduce process cost, and improve deposition rate and coating efficiency.

[0171] It should be noted that the physical vapor deposition used to form the P-type passivation stack 130 is not limited to the magnetron sputtering and electron beam evaporation mentioned above. It can also be reactive plasma deposition (RPD), arc plasma deposition, or thermal evaporation, laser beam or ion beam evaporation in vacuum deposition. These will not be listed here.

[0172] In some embodiments, the method for fabricating a solar cell may further provide at least two target units, and for each target unit, forming a first doped amorphous silicon layer 1301 and a second doped amorphous silicon layer 1302 on the target structure in the thickness direction based on physical vapor deposition, and performing an annealing process to form alternating first doped layers 131 and second doped layers 132 on the side of the tunneling passivation layer away from the substrate.

[0173] The method for fabricating solar cells can be based on multiple target units, using magnetron sputtering or electron beam evaporation to form alternating layers of a first doped amorphous silicon layer 1301 and a second doped amorphous silicon layer 1302 on the side of the tunneling passivation layer 120 away from the substrate 110.

[0174] In this embodiment, for ease of explanation, an example is provided where a first doped amorphous silicon layer 1301 and a second doped amorphous silicon layer 1302 constitute a doped amorphous silicon unit. For example, one target unit corresponds to the formation of a doped amorphous silicon stack. The doping concentration of each target element in each target unit is different, or the number of targets and the area of ​​the targets in each target unit are different. For example, the formation of two doped amorphous silicon units using magnetron sputtering is described.

[0175] First, a first gallium-doped amorphous silicon layer 1301 is formed on the side of the tunneling passivation layer 120 away from the substrate 110 using a gallium-doped material hybrid target based on the first target unit. Then, in the same PVD chamber, a first boron-doped amorphous silicon layer 1302 is formed on the side of the first gallium-doped amorphous silicon layer 1301 away from the tunneling passivation layer 120 using a boron-doped material hybrid target in the first target unit. Next, in the same PVD chamber, a second gallium-doped amorphous silicon layer 1301 is formed on the side of the first boron-doped amorphous silicon layer 1302 away from the tunneling passivation layer 120 using a gallium-doped material hybrid target in the second target unit. Finally, in the same PVD chamber, a second boron-doped amorphous silicon layer 1302 is formed on the side of the second gallium-doped amorphous silicon layer 1301 away from the tunneling passivation layer 120 using a boron-doped material hybrid target in the second target unit. In this way, multiple target units can be arranged in a continuous manner to form multiple stacked doped amorphous silicon units. Finally, an annealing process is performed to form multiple alternating stacked first and second doped layers.

[0176] In this embodiment, magnetron sputtering technology can be used to form multiple alternating stacked first doped layers 131 and second doped layers 132, which can simplify the process steps of forming the first doped layers 131 and second doped layers 132, and significantly reduce the process cost. In addition, this technology can be closer to the conditions of mass production, and can achieve large area, high capacity, stable and controllable process; it can also improve the passivation effect, reduce the contact resistivity, and significantly reduce the cost.

[0177] Optionally, multiple doped amorphous silicon units can be formed on the side of the tunneling passivation layer away from the substrate using electron beam evaporation based on multiple target units. For example, multiple target units can be arranged sequentially in corresponding electron beam process cavities, and the corresponding target units can be bombarded in the deposition sequence to form multiple stacked doped amorphous silicon units. Finally, an annealing process is performed to form multiple alternating stacked first doped layers 131 and second doped layers 132. This simplifies the process steps for forming P-type passivation stacks, significantly reduces process costs, and allows for closer approximation to mass production conditions. It enables large-area, high-throughput, stable, and controllable processes; it also improves passivation effect, reduces contact resistivity, and significantly reduces costs.

[0178] Referring to Figure 12, in some embodiments, during the fabrication of a solar cell, before forming the first doped amorphous silicon layer 1301, the method for fabricating the solar cell may further include providing an initial target material and forming an interface amorphous silicon layer 1303 on the side of the tunneling passivation layer 120 away from the substrate based on the initial target material. The first doped amorphous silicon layer 1301 is located on the side of the interface amorphous silicon layer 1303 away from the tunneling passivation layer 120.

[0179] The arrangement order of the initial target 103, the gallium-doped hybrid target 101, and the boron-doped hybrid target 102 can be referred to in Figures 9 and 10. The steps of providing the initial target and providing at least one gallium-doped hybrid target 101 and at least one boron-doped hybrid target 102 can be performed simultaneously or separately. The initial target 103 can be understood as an undoped intrinsic target or a lightly doped target. Before forming the first doped amorphous silicon layer 1301, argon gas can be used as the sputtering gas to bombard the initial target 103 to form an interface amorphous silicon layer 1303 on the side of the tunneling passivation layer 120 away from the substrate 110. Based on this, a gallium-doped amorphous silicon layer 1301 and a boron-doped amorphous silicon layer 1302 are further formed on the interface amorphous silicon layer 1303. Then, annealing is performed, which activates the doping elements in the interface amorphous silicon layer 1303, gallium-doped amorphous silicon layer 1301 and boron-doped amorphous silicon layer 1302 to begin diffusion, which can further improve the passivation performance of the solar cell.

[0180] Alternatively, during the process of forming a doped amorphous silicon stack on the side of the tunnel passivation layer 120 away from the substrate by electron beam evaporation, an interface amorphous silicon layer 1303 can also be formed on the side of the tunnel passivation layer away from the substrate by bombarding the initial target 103 with a high-energy electron beam before forming the gallium-doped amorphous silicon layer 1301, based on the provided initial target 103 (refer to Figures 9 and 10).

[0181] In some embodiments, before forming the second doped amorphous silicon layer 1302, the method for fabricating a solar cell further includes the step of forming a first interface oxide layer 140 on the side of the first doped amorphous silicon layer 1301 away from the tunneling passivation layer.

[0182] As shown in Figure 13, by way of example, a first interface oxide layer 140 can be formed on the side of the gallium-doped amorphous silicon layer 1301 away from the tunneling passivation layer 120 by means of physical vapor deposition, chemical vapor deposition, etc. The material of the first interface oxide layer 140 can be a dielectric material, such as at least one of silicon oxide, magnesium fluoride, silicon oxide, amorphous silicon, polycrystalline silicon, silicon carbide, silicon nitride, silicon oxynitride, aluminum oxide, or titanium oxide.

[0183] For example, the first interface oxide layer 140 can be formed using physical vapor deposition (PVD), which employs the same process technology as that used to form the doped amorphous silicon layer, thus further reducing costs. For instance, a gallium-doped amorphous silicon layer 1301 is formed based on PVD, and the first interface oxide layer 140 is formed on the side of the gallium-doped amorphous silicon layer 1301 away from the tunneling passivation layer. Then, a boron-doped amorphous silicon layer is formed on the first interface oxide layer 140 based on PVD.

[0184] In this example, by forming a first interface oxide layer 140 between the first doped layer 131 and the second doped layer 132, the diffusion rate of boron can be reduced to avoid excessively high concentrations of B elements from damaging the passivation effect of the ultrathin tunneling passivation layer, and the passivation performance between the first doped layer 131 and the second doped layer 132 can also be improved.

[0185] In some embodiments, after forming a first doped amorphous silicon layer 1301 and a second doped amorphous silicon layer 1302 on the target structure in the thickness direction for each target unit, the solar cell fabrication method may further include the step of forming a second interface oxide layer 150 on the side of the second doped amorphous silicon layer 1302 away from the first doped amorphous silicon layer 1301.

[0186] It is understandable that after forming the first doped amorphous silicon layer 1301 and the second doped amorphous silicon layer 1302 for each target unit, a second interface oxide layer 150 can be formed on the side of the second gallium-doped amorphous silicon layer away from the first gallium-doped amorphous silicon layer. The formation method of the second interface oxide layer 150 is also the same as that of the first interface oxide layer 140, and will not be described again here. By forming the second interface oxide layer 150 between the two doped amorphous silicon units, the solar cell can possess superior passivation performance.

[0187] For ease of explanation, taking magnetron sputtering to form a solar cell as an example, the fabrication method of the solar cell shown in Figure 2 is illustrated, which may include the following steps:

[0188] Step 1: Select an N-type silicon wafer with a thickness of 130μm as substrate 110, and remove the surface cutting damage layer by alkaline polishing process.

[0189] Step 2: Place an N-type silicon wafer into a plate-type PECVD equipment to deposit a tunneling passivation layer 120, such as a SiOx layer. Exemplarily, N2O and Ar are used as process gases, and a 1nm-2nm tunneling passivation layer 120 is prepared at a temperature of 400-500°C.

[0190] Step 3: The silicon wafer is continuously transferred into the PVD process chamber, and multiple targets are placed side-by-side to deposit a doped polycrystalline silicon layer on the back side of the wafer. For example, Ar is used as the sputtering gas to deposit an interfacial amorphous silicon layer on the back side of the wafer using an intrinsic or lightly doped target; a Ga-doped amorphous silicon layer is deposited using a Ga-doped target; and a B-doped amorphous silicon layer is deposited using a B-doped target. The thickness of the Ga-doped amorphous silicon layer is 5-100 nm, and the thickness of the B-doped amorphous silicon layer is 10-200 nm. The Ga source precursor is used as the doping gas with a doping percentage of approximately 0.1%-10%, and the B source precursor is used as the doping gas with a doping percentage of approximately 0.1%-10%. Furthermore, hydrogen gas can be incorporated into the Ga and B sources, and appropriate amounts of methane or oxygen can be introduced to adjust the light transmittance of the polycrystalline silicon film. During the sputtering process, the temperature of the substrate 110 can be maintained at 200-450℃, which can further improve the stability and uniformity of the gallium-doped amorphous silicon layer 1301 and boron-doped amorphous silicon layer 1302 formed by magnetron sputtering, and improve the yield of solar cell fabrication.

[0191] Step 4: Finally, using N2O and Ar as process gases, deposit a 10-40nm thick silicon oxide layer as a protective layer.

[0192] Step 5: Next, place it in a tube annealing furnace for annealing at 880-1050℃, and the doping elements of the amorphous silicon layer will be activated and diffuse into the silicon substrate 110.

[0193] Step 6: Remove SiOx from the front surface of the silicon substrate 110 by single-sided chain HF, and then polish the front surface of the silicon substrate 110 by alkaline polishing.

[0194] Step 7: Prepare N-type passivated polysilicon 173 using PECVD process. For example, annealing can be performed at 880-950℃ in a tube annealing furnace. Then, remove the PSG in the second region F2 by laser etching, and after etching the n-Poly with alkaline solution, prepare the front surface texturing structure.

[0195] Step 8: Deposit AlOx and SiNx to form passivation and antireflection layers on the front and back sides of the silicon substrate 110. For example, an aluminum oxide layer 184 (the layer closest to the substrate) with a thickness of 5 nm can be deposited on the front side using atomic layer deposition (ALD) technology; then, silicon nitride / silicon oxynitride layers 184 (the layer furthest from the substrate) and 185 with a thickness of 85 nm and a refractive index of 1.8-2.2 are deposited on the front and back sides.

[0196] Step 9: Using screen printing, the main gate and fine gate metal electrodes are printed simultaneously on the front and back sides. Passivation is further improved by sintering and light annealing to complete the device fabrication.

[0197] It should be noted that the method for preparing solar cells is not limited to the examples described above. Each preparation process step can be adjusted according to different types of solar cells. In the embodiments of this application, no specific limitations are made on the preparation method of the solar cells applicable to this application or the specific structure of the solar cells.

[0198] Referring to FIG14, this embodiment provides a photovoltaic module 200, including at least one battery string 210. The battery string 210 includes at least two solar cells 100 as described in any of the preceding embodiments, and the solar cells 100 can be connected together by string welding.

[0199] For example, multiple solar cells can be connected in series by soldering ribbons, thereby collecting the electrical energy generated by each individual solar cell for subsequent transmission. Of course, the solar cells can be arranged at intervals or stacked together in a shingled configuration. Specifically, the first electrode 191 of each solar cell 100 is connected to the second electrode 192 of an adjacent solar cell 100 by soldering ribbons, and the second electrode 192 of each solar cell 100 is connected to the first electrode 191 of another adjacent solar cell 100 by soldering ribbons, thus connecting multiple solar cells 100 in series.

[0200] For example, the photovoltaic module 200 also includes an encapsulation layer and a cover plate (not shown). The encapsulation layer covers the surface of the cell string 210, and the cover plate covers the surface of the encapsulation layer away from the cell string 210. The solar cells are electrically connected in a single piece or in multiple segments to form multiple cell strings 210, which are electrically connected in series and / or parallel. Specifically, in some embodiments, the multiple cell strings 210 can be electrically connected to each other via conductive links. The encapsulation layer covers the surface of the solar cells. For example, the encapsulation layer can be an organic encapsulation film such as an ethylene-vinyl acetate copolymer film, a polyethylene octene co-elastomer film, or a polyethylene terephthalate film. The cover plate can be a light-transmitting cover plate such as a glass cover plate or a plastic cover plate.

[0201] In the description of this specification, references to terms such as "one embodiment," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0202] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0203] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing a solar cell, characterized in that, include: A substrate is provided, the substrate including a first surface and a second surface disposed opposite to each other along the thickness direction of the substrate; A tunneling passivation layer is formed on the first surface of the substrate; as well as Based on physical vapor deposition, a first doped layer and a second doped layer are stacked at least on the side of the tunneling passivation layer away from the substrate to form a first doped layer and a second doped layer, wherein the doping type of the first doped layer and the second doped layer is p-type, the doping elements of the first doped layer and the second doped layer are not completely the same, the first doped layer includes at least gallium, and the second doped layer includes at least boron.

2. The method according to claim 1, characterized in that, The method of forming a first doped layer and a second doped layer by stacking at least on the side of the tunneling passivation layer away from the substrate based on physical vapor deposition includes: A target unit is provided; wherein the target unit includes a gallium-doped hybrid material target and a boron-doped hybrid material target, the gallium-doped hybrid material target and the boron-doped hybrid material target are arranged in a deposition sequence; Based on the target unit, a first doped amorphous silicon layer and a second doped amorphous silicon layer are formed on the side of the tunneling passivation layer away from the substrate using physical vapor deposition; wherein, the first doped amorphous silicon layer includes at least gallium, and the second doped amorphous silicon layer includes at least boron; and Annealing is performed to form the first doped layer and the second doped layer.

3. The method according to claim 2, characterized in that, The method of forming a first doped amorphous silicon layer and a second doped amorphous silicon layer on the side of the tunneling passivation layer away from the substrate by physical vapor deposition includes: Based on the mixed gas and the target unit, the first doped amorphous silicon layer and the second doped amorphous silicon layer are formed on the side away from the substrate by magnetron sputtering on the tunneling passivation layer; wherein, the mixed gas includes sputtering gas and doping gas.

4. The method according to claim 3, characterized in that, The doping gas includes a gallium source precursor and a boron source precursor.

5. The method according to claim 4, characterized in that, The gallium source precursor includes trimethylgallium, and the boron source precursor includes at least one of diboron hexahydrogenate and trimethyl borate.

6. The method according to any one of claims 3 to 5, characterized in that, The doping gas also includes at least one of methane, carbon dioxide, and ammonia.

7. The method according to claim 6, characterized in that, The doped gas includes methane, carbon dioxide, and ammonia; wherein the doping percentage of methane is 10%-50%, the doping percentage of ammonia is 0.5%-30%, and the doping percentage of carbon dioxide is 0.1%-50%.

8. The method according to claim 2, characterized in that, The method of forming a first doped amorphous silicon layer and a second doped amorphous silicon layer on the side of the tunneling passivation layer away from the substrate by physical vapor deposition includes: By bombarding each of the mixed material targets in the target unit with a high-energy electron beam in the order of deposition, the first doped amorphous silicon layer and the second doped amorphous silicon layer are deposited on the side of the tunneling passivation layer away from the substrate.

9. The method according to any one of claims 2 to 8, characterized in that, The target unit includes at least two gallium-doped hybrid material targets and at least two boron-doped hybrid material targets; The gallium-doped hybrid material targets are arranged adjacent to each other, and the boron-doped hybrid material targets are arranged adjacent to each other.

10. The method according to any one of claims 1 to 9, characterized in that, The number of the first doped layer and the second doped layer are each at least two; Each of the first doped layer and the second doped layer is alternately formed on the side of the tunneling passivation layer away from the substrate.

11. The method according to claim 10, characterized in that, The first doped layer and the second doped layer are alternately formed on the side of the tunneling passivation layer away from the substrate, including: At least two target units are provided; the target units include gallium-doped hybrid material targets and boron-doped hybrid material targets, the gallium-doped hybrid targets and the boron-doped hybrid targets are arranged in a deposition sequence; For each target unit, a first doped amorphous silicon layer and a second doped amorphous silicon layer are formed on the target structure in the thickness direction based on physical vapor deposition; wherein, the target structure includes a tunneling passivation layer or each of the second doped amorphous silicon layers; An annealing process is performed to form alternating first doped layers and second doped layers on the side of the tunneling passivation layer away from the substrate.

12. The method according to any one of claims 2 to 9 and 11, characterized in that, Before forming the first doped amorphous silicon layer, the method further includes: An initial target is provided, wherein the initial target is disposed adjacent to the gallium-doped hybrid material target; An interfacial amorphous silicon layer is formed on the side of the tunneling passivation layer away from the substrate based on the initial target material; wherein the first doped amorphous silicon layer is located on the side of the interfacial amorphous silicon layer away from the tunneling passivation layer.

13. The method according to claim 12, characterized in that, The initial target material includes an intrinsic target material without P-type elements or a mixed target material lightly doped with P-type elements.

14. The method according to any one of claims 2 to 9 and 11, characterized in that, Before forming the second doped amorphous silicon layer, the method further includes: A first interface oxide layer is formed on the side of the first doped amorphous silicon layer away from the tunneling passivation layer; wherein, the second doped amorphous silicon layer is formed on the side of the first interface oxide layer away from the first doped amorphous silicon layer.

15. The method according to claim 11, characterized in that, After forming a first doped amorphous silicon layer and a second doped amorphous silicon layer on the target structure in the thickness direction for each target unit, the method further includes: A second interface oxide layer is formed on the side of the second gallium-doped amorphous silicon layer away from the first gallium-doped amorphous silicon layer.

16. The method according to any one of claims 1 to 15, characterized in that, The physical vapor deposition also includes one of vacuum evaporation and arc plasma deposition.

17. A solar cell, characterized in that, include: The substrate includes a first surface and a second surface disposed opposite to each other along the thickness direction of the substrate; A tunneling passivation layer is located on the first surface of the substrate; The first doped layer is located on the side of the tunneling passivation layer away from the substrate; The second doped layer is located on the side of the first doped layer away from the tunneling passivation layer; Wherein, the first doped layer and the second doped layer are both p-type doped, and the doping elements of the first doped layer and the second doped layer are not exactly the same. The first doped layer includes at least gallium, and the second doped layer includes at least boron. as well as The first electrode is in contact with the second doped layer.

18. The solar cell according to claim 17, characterized in that, The doping element of the first doped layer includes gallium. The doping element of the second doped layer includes boron, or the doping element of the second doped layer includes both boron and gallium.

19. The solar cell according to claim 17 or 18, characterized in that, It includes at least two first doped layers and at least two second doped layers, wherein, in the thickness direction, each first doped layer and each second doped layer are alternately stacked on the side of the tunneling passivation layer away from the substrate.

20. The solar cell according to claim 19, characterized in that, In the direction from the second doped layer to the tunneling passivation layer, the concentration of gallium in the first doped layer gradually decreases.

21. The solar cell according to claim 20, characterized in that, The maximum concentration of gallium in each of the first doped layers ranges from 8E19cm⁻¹ -3 -12E19 / cm -3 .

22. The solar cell according to any one of claims 19 to 21, characterized in that, In the direction from the second doped layer to the tunneling passivation layer, the concentration of boron in the second doped layer gradually decreases.

23. The solar cell according to claim 22, characterized in that, The maximum concentration of boron in each of the second doped layers ranges from 5E19cm⁻¹ -3 -11E19 / cm -3 .

24. The solar cell according to any one of claims 17 to 23, characterized in that, The thickness of the first doped layer ranges from 10 nm to 150 nm, and the thickness of the second doped layer ranges from 5 nm to 150 nm.

25. The solar cell according to any one of claims 17 to 24, characterized in that, Also includes: A first interface oxide layer is located between the first doped layer and the second doped layer in the thickness direction.

26. The solar cell according to any one of claims 17 to 25, characterized in that, Also includes: The second interface oxide layer is located on the side of the second doped layer away from the first doped layer in the thickness direction.

27. The solar cell according to any one of claims 17 to 26, characterized in that, Also includes: An interface polysilicon layer is located on the side of the tunneling passivation layer away from the substrate in the thickness direction; wherein the first doped layer is located on the side of the interface polysilicon layer away from the tunneling passivation layer.

28. The solar cell according to any one of claims 17 to 27, characterized in that, Both the first doped layer and the second doped layer are prepared by physical vapor deposition.

29. The solar cell according to claim 28, characterized in that, The physical vapor deposition includes one of vacuum evaporation, magnetron sputtering, reactive plasma deposition, and arc plasma deposition.

30. The solar cell according to any one of claims 17-29, characterized in that, The first surface is a backlight surface; wherein, the solar cell further includes: The first passivation anti-reflection layer is located on the side of the second doped layer away from the first doped layer; A first polysilicon conductive layer, a second passivation antireflection layer, a second polysilicon conductive layer, and a conductive passivation layer are sequentially stacked on the second surface of the substrate; wherein, the first polysilicon conductive layer and the second polysilicon conductive layer are both N-type doped. The second electrode is disposed on one side of the second surface of the substrate and is in contact with the conductive passivation layer.

31. The solar cell according to any one of claims 17-29, characterized in that, The first surface is a backlight surface, and the second surface includes a first region and a second region; wherein, the solar cell further includes: At least one third polysilicon conductive layer is stacked in the first region; the doping type of the third polysilicon conductive layer is N-type. At least one third passivation and anti-reflection layer is stacked in the second region; At least one fourth passivation antireflection layer is stacked on the side of the second doped layer away from the first doped layer; The second electrode is disposed on one side of the second surface of the substrate and is in contact with the third polycrystalline silicon conductive layer.

32. The solar cell according to any one of claims 17-29, characterized in that, The first surface is a light-receiving surface, and the first surface includes a third region and a fourth region, wherein the tunneling passivation layer is located in the third region of the first surface; wherein the solar cell further includes: A tunneling oxide layer, a third doped layer, and a fifth passivation antireflection layer are stacked on the second surface of the substrate, wherein the doping type of the third doped layer is different from that of the first doped layer; The sixth passivation antireflection layer is located on the side of the second doped layer away from the first doped layer and in the fourth region on the first surface; The second electrode is disposed on one side of the second surface of the substrate and is in contact with the third doped layer.

33. A photovoltaic module, characterized in that, It includes at least one battery string, the battery string comprising at least two solar cells prepared by the method of manufacturing a solar cell as described in any one of claims 1-16, or, as described in any one of claims 17-32.

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