Solar cells, their fabrication methods, tandem cells and photovoltaic modules

Abstract

This application relates to the photovoltaic field, providing a solar cell, its fabrication method, a tandem cell, and a photovoltaic module. The solar cell includes: a silicon substrate having opposing first and second surfaces; a composite passivation layer located on the first surface of the silicon substrate, the composite passivation layer comprising multiple AlSiOx layers, each AlSiOx layer having Al-O bonds, the multiple AlSiOx layers being stacked in a first direction, wherein the volume content of Al in the AlSiOx layers increases and the volume content of Si decreases in the first direction, the first direction being the direction from the second surface to the first surface. The solar cell provided by this application embodiment can at least improve the photoelectric conversion efficiency of the solar cell.

Description

Technical Field

[0001] This application relates to the photovoltaic field, and in particular to a solar cell, a method for its fabrication, a tandem cell, and a photovoltaic module. Background Technology

[0002] In the existing technology, the passivation effect of the passivation structure of solar cells is insufficient, making it difficult to meet the passivation requirements of high-efficiency solar cells, which in turn leads to a decrease in the photoelectric conversion efficiency of the cells. Summary of the Invention

[0003] This application provides a solar cell, its preparation method, a tandem cell, and a photovoltaic module, which at least help improve the photoelectric conversion efficiency of the solar cell.

[0004] According to some embodiments of this application, one aspect of this application provides a solar cell, including:

[0005] A silicon substrate has a first surface and a second surface opposite to each other; a composite passivation layer is located on the first surface of the silicon substrate, the composite passivation layer includes a plurality of AlSiOx layers, the AlSiOx layers have Al-O bonds, the plurality of AlSiOx layers are stacked in a first direction, in the first direction, the volume content of Al in the AlSiOx layers increases and the volume content of Si decreases, the first direction is the direction from the second surface to the first surface.

[0006] In some embodiments, the first surface has a first region and a second region alternately arranged along a second direction, and the solar cell further includes a first doped conductive layer and a second doped conductive layer, wherein the first doped conductive layer is located on the second surface and has a first doping type; the second doped conductive layer is located in the first region and has a second doping type, and the first doping type is opposite to the second doping type.

[0007] In some embodiments, the second surface has a third region and a fourth region alternately arranged along a second direction, and the solar cell further includes a first doped conductive layer and a second doped conductive layer, wherein the first doped conductive layer is located in the fourth region and has a first doping type; the second doped conductive layer is located in the third region and has a second doping type, and the first doping type is opposite to the second doping type.

[0008] In some embodiments, the volume content of Al in each AlSiOx layer is independently selected from 5% to 70%, and the volume content of Si is independently selected from 10% to 70%.

[0009] In some embodiments, the AlSiOx layer has 2 to 6 layers.

[0010] In some embodiments, the AlSiOx layer comprises nanoparticles.

[0011] In some embodiments, the composite passivation layer includes at least one AlSiOx layer and at least one first passivation layer, wherein the AlSiOx layer and the first passivation layer are alternately stacked along a first direction, the first direction being the direction from the second surface to the first surface.

[0012] In some embodiments, the first passivation layer includes a SiO2 layer.

[0013] In some embodiments, the volume content of O in the first passivation layer is 1% to 10%.

[0014] According to some embodiments of this application, another aspect of this application provides a method for fabricating a solar cell. The method includes: providing a silicon substrate; forming a composite passivation layer on one side of the silicon substrate using an atomic layer deposition process. The composite passivation layer includes multiple AlSiOx layers, each AlSiOx layer having Al-O bonds. The AlSiOx layer is prepared using a silicon-containing aluminum precursor source and an oxidant. The aluminum precursor source includes TEA.

[0015] In some embodiments, the step of preparing the AlSiOx layer includes: introducing the silicon-containing aluminum precursor source into a reaction chamber to form an aluminum-silicon film on one side of the silicon substrate; purging the reaction chamber with an inert gas; and introducing the oxidant into the reaction chamber to react with the aluminum-silicon film to generate the AlSiOx layer.

[0016] In some embodiments, the time for introducing the silicon-containing aluminum precursor source is 0.2~0.55s, the temperature is 180~250°C, the flow rate of the carrier gas carrying the silicon-containing aluminum precursor source is 50~100 sccm, and the concentration of the oxidant is 100~150 g / m³. 2 The oxidant is introduced for 0.3 to 0.8 seconds, and the reaction pressure between the oxidant and the aluminum-silicon film is 1 to 5 Torr.

[0017] According to some embodiments of this application, another aspect of this application provides a tandem battery, comprising: a bottom battery, which is the solar cell described above, or a solar cell prepared by the method for preparing the solar cell described above; and a top battery located on the bottom battery.

[0018] According to some embodiments of this application, another aspect of this application provides a photovoltaic module, including: a battery string, which is formed by connecting multiple solar cells, or by connecting solar cells prepared by the method described above, or by connecting multiple stacked cells; an encapsulating film for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulating film facing away from the battery string.

[0019] The technical solution provided in this application has at least the following advantages:

[0020] The solar cell of this application introduces a composite passivation layer, which includes an AlSiOx layer containing Al-O bonds. The shorter bond length of the Al-O bonds allows for smaller distances between adjacent atoms in the AlSiOx layer, enabling the formation of more bonding points within a relatively small space. This results in a denser atomic network within the AlSiOx layer, leading to greater compactness. This increased compactness makes the AlSiOx film more uniform, reduces film defects, and improves the passivation effect. The stable structure of the Al-O bonds and the low number of defect energy levels on the AlSiOx layer surface further reduce the interface state density, enhancing the passivation effect of the composite passivation layer. As the Al volume content increases away from the silicon substrate, more Al-O bonds are formed. These bonds attract holes near the silicon substrate, causing them to recede and reducing recombination near the substrate, thus achieving chemical passivation. The AlSiOx layer with a higher Si content closer to the silicon substrate can adhere more tightly to the silicon substrate, reducing defects between the AlSiOx layer and the silicon substrate. As the Si volume content gradually decreases away from the silicon substrate, Si dangling bonds are reduced, which helps to lower the defect state density at the film interface, thereby improving the passivation effect of the cell. The improved passivation effect, in turn, improves the photoelectric conversion efficiency of the cell. Attached Figure Description

[0021] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the drawings in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this application or in the conventional art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A cross-sectional structural schematic diagram of a first type of TOPCon solar cell provided in an embodiment of this application;

[0023] Figure 2 A cross-sectional structural schematic diagram of a second type of TOPCon solar cell provided in an embodiment of this application;

[0024] Figure 3 A cross-sectional structural schematic diagram of a first type of back-contact solar cell provided in an embodiment of this application;

[0025] Figure 4 A cross-sectional structural schematic diagram of a second type of back-contact solar cell provided in an embodiment of this application;

[0026] Figure 5 A schematic flowchart illustrating a method for fabricating a solar cell according to an embodiment of this application;

[0027] Figure 6 for Figure 5 A schematic diagram of the cross-sectional structure of a silicon substrate after a composite passivation layer is formed on the silicon substrate in the fabrication method of solar cells;

[0028] Figure 7 This is a cross-sectional structural diagram of a stacked battery provided in an embodiment of this application;

[0029] Figure 8 This is a cross-sectional structural diagram of a photovoltaic module provided in one embodiment of this application.

[0030] The above figures include the following reference numerals:

[0031] 10. Silicon substrate; 20. Composite passivation layer; 21. AlSiOx layer; 22. First passivation layer; 30. First doped conductive layer; 40. Second doped conductive layer; 50. Back passivation layer; 60. Anti-reflection layer; 70. First electrode; 80. Second electrode; 91. Bottom cell; 92. Top cell; 100. Solar cell; 101. Encapsulating film; 102. Cover plate; 103. Conductive strip;

[0032] 11. Silicon substrate; 200. Composite passivation layer; 210. AlSiOx layer; 220. First passivation layer; 31. First doped conductive layer; 41. Second doped conductive layer; 51. Back passivation layer; 61. Anti-reflection layer; 71. First electrode; 81. Second electrode. Detailed Implementation

[0033] As can be seen from the background technology, the passivation effect of the passivation structure of solar cells is insufficient, making it difficult to meet the passivation requirements of high-efficiency solar cells.

[0034] This application provides a solar cell, a method for preparing a solar cell, a tandem cell, and a photovoltaic module.

[0035] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0036] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0037] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0038] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0039] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0040] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" 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. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0041] In the accompanying drawings corresponding to the embodiments of this application, the thickness and area of ​​the layers are enlarged for better understanding and ease of description. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component may be "directly" located on the surface of the other component, or there may be a third component between the two components. Conversely, when describing a component on the surface of another component, or when another component is formed or disposed on the surface of a component, it indicates that there is no third component between the two components. Furthermore, when describing a component as being "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0042] In the description of the embodiments of this application, when a component "includes" another component, other components are not excluded unless otherwise stated, and other components may be further included. Furthermore, when a component such as a layer, film, region, or plate is referred to as being "on / located" on another component, it can be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or another component may be present therein. Moreover, when a component such as a layer, film, region, or plate is "directly located" on another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it indicates that no other components are located therein.

[0043] The terminology used in the description of the various embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims, the word "part" is also intended to include the plural form, unless the context clearly indicates otherwise. Components include layers, films, regions, or plates, etc.

[0044] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0045] According to some embodiments of this application, one aspect of this application provides a solar cell, such as... Figures 1 to 2As shown, the TOPCon solar cell includes: a silicon substrate 10 having opposing first and second surfaces; a composite passivation layer 20 located on the first surface of the silicon substrate 10, the composite passivation layer 20 including multiple AlSiOx layers 21, each AlSiOx layer 21 having Al-O bonds, the multiple AlSiOx layers 21 being stacked in a first direction X, wherein the volume content of Al in the AlSiOx layers 21 increases and the volume content of Si decreases in the first direction X, the first direction X being the direction from the second surface to the first surface. Figures 3 to 4 As shown, the back-contact solar cell includes: a silicon substrate 11 having opposing first and second surfaces; a composite passivation layer 200 located on the first surface of the silicon substrate 11, the composite passivation layer 200 including multiple AlSiOx layers 210, the AlSiOx layers 210 having Al-O bonds, the multiple AlSiOx layers 210 being stacked in a first direction X, in the first direction X, the volume content of Al in the AlSiOx layers 210 increasing and the volume content of Si decreasing, the first direction X being the direction from the second surface to the first surface.

[0046] This application introduces a composite passivation layer into solar cells, comprising multiple AlSiOx layers. Compared to existing technologies with only a single passivation layer, this provides better passivation for solar cells. Furthermore, the AlSiOx layers contain Al-O bonds. The shorter bond length of these Al-O bonds allows for closer distances between adjacent atoms within the AlSiOx layer, enabling the formation of more bonding points in a relatively small space. This results in a denser atomic network within the AlSiOx layer, leading to greater compactness. This increased compactness results in a more uniform AlSiOx film, reducing defects and enhancing passivation. The stable structure of the Al-O bonds reduces the number of defect energy levels on the AlSiOx layer surface, lowering the interface state density and further improving the passivation effect. As the Al volume content increases away from the silicon substrate, more Al-O bonds are formed. These bonds attract holes near the silicon substrate, causing them to recede and reducing recombination on the silicon substrate surface, thus enhancing chemical passivation. The AlSiOx layer near the silicon substrate has a higher Si content, which allows it to adhere more tightly to the silicon substrate and reduce defects between the AlSiOx layer and the silicon substrate. As the Si volume content gradually decreases away from the silicon substrate, the Si dangling bonds on the surface of the AlSiOx layer can be reduced. This helps to reduce the defect state density at the film interface, thereby improving the passivation effect of the cell and increasing the efficiency of the solar cell.

[0047] In the above embodiments, multiple AlSiOx layers can be in direct contact with each other, or other structural layers can be inserted between two adjacent AlSiOx layers. This application does not specifically limit the specific arrangement.

[0048] In the above embodiments, the silicon substrate material can be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon. The elemental semiconductor material can be monocrystalline, polycrystalline, amorphous, or microcrystalline (a state simultaneously possessing both monocrystalline and amorphous states is called microcrystalline). For example, silicon can be at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon.

[0049] In the above embodiments, the silicon substrate material can also be a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, silicon germanide, silicon carbide, gallium arsenide, indium gallium dihydrogen phosphate, perovskite, cadmium telluride, and copper indium selenide. The silicon substrate can also be a sapphire silicon substrate, a silicon-on-insulator substrate, or a germanium-silicon-on-insulator substrate.

[0050] In the above embodiments, the N-type silicon substrate is doped with an N-type dopant element, which can be at least one of group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type silicon substrate is doped with a P-type dopant element, which can be at least one of group III elements such as boron (B), aluminum (Al), gallium (Ga), or gallium (In). Optionally, the thickness of the N-type silicon substrate can be 100 μm to 210 μm, such as 130 μm, 170 μm, and 190 μm.

[0051] In the above embodiments, the volume content of Al and Si in the AlSiOx layer of the battery of this application can be detected by secondary ion mass spectrometry (SIMS). The detection process can be as follows:

[0052] Sample preparation: The solar cell of this application is sliced ​​to obtain a cross-sectional sample. The slicing can be achieved by focused ion beam (FIB) or ultrathin slicing technology.

[0053] Surface cleaning: The surface can be gently cleaned using methods such as argon ion sputtering to ensure that the sample surface is free of contamination.

[0054] Ion bombardment: using a primary ion beam with controllable energy, such as Ga... + Or O - The primary ions bombard the sample surface. Their energies range from several thousand electron volts (keV) to tens of electron volts (keV), enough to detonate the AlSiOx layer. + and Si + Ions detach from the sample surface.

[0055] Ion extraction and analysis: The Al obtained above + and Si+ Ions are extracted and fed into a mass analyzer, where they are separated and counted based on their mass-to-charge ratio (m / z). Al + and Si + The intensity ratio reflects the relative volume content of Al and Si in the AlSiOx layer, thus yielding the volume content of Al and Si.

[0056] The composite passivation layer of this application can be used in TOPCon batteries, such as in some embodiments. Figures 1 to 2 As shown, the first surface has a first region A and a second region B alternately arranged along the second direction Y. The solar cell also includes a first doped conductive layer 30 and a second doped conductive layer 40, wherein the first doped conductive layer 30 is located on the second surface and has a first doping type; the second doped conductive layer 40 is located in the first region A and has a second doping type, and the first doping type is opposite to the second doping type.

[0057] In the above embodiments, the first region refers to the region in the battery where electrodes are formed, also known as the metal region. The second region is the region in the battery other than the first region, also known as the non-metal region.

[0058] The composite passivation layer of this application can be used in back contact batteries, such as in some embodiments. Figures 3 to 4 As shown, the second surface has a third region C and a fourth region D alternately arranged along the second direction Y. The solar cell also includes a first doped conductive layer 31 and a second doped conductive layer 41, wherein the first doped conductive layer 31 is located in the fourth region D and has a first doping type; the second doped conductive layer 41 is located in the third region C and has a second doping type, and the first doping type is the opposite of the second doping type. The composite passivation layer of this application can be applied to the above-mentioned types of cells and their stacked cells, and has a wide range of applications.

[0059] In the above embodiments, the first surface of the silicon substrate is the front side and the second surface is the back side, that is, the solar cell is a single-sided cell, the front side can be used as the light-receiving surface to receive incident light, and the back side is used as the back light surface.

[0060] The first surface and the second surface mentioned above can be flat surfaces or non-flat surfaces, that is, the first surface can be a flat surface or a non-flat surface, the second surface can be a flat surface or a non-flat surface, and the first surface and the second surface can be the same or different.

[0061] In the above embodiments, both the first and second surfaces are non-flat surfaces. Non-flat surfaces can increase internal reflection of incident light, thereby further improving the light utilization efficiency of the solar cell. More specifically, the cross-section of the non-flat surface along the first predetermined direction is a line segment. This line segment can include at least one of straight segments and curved segments; that is, the line segment can be composed of straight segments, curved segments, or a combination of both. In the case where only straight segments are used, the line segment is composed of multiple sequentially connected straight segments. The first predetermined direction is the thickness direction of the silicon substrate.

[0062] In the above embodiments, the first doped conductive layer and the second doped conductive layer can be doped polycrystalline silicon layers, silicon carbide layers, or composite layers of doped polycrystalline silicon layers and silicon carbide layers. For example, they can be only silicon carbide or only polycrystalline silicon, or they can be doped materials of silicon carbide and polycrystalline silicon. When the first doped conductive layer is doped polycrystalline silicon, it can serve as a field passivation layer, forming band bends on the silicon wafer surface to achieve selective carrier transport and reduce recombination losses. The thickness of the first doped conductive layer and the second doped conductive layer can be 80nm~100nm, such as 80nm and 95nm. The specific thickness and material are not limited in this application and can be selected according to the actual situation.

[0063] In the above embodiments, such as Figures 1 to 2 As shown, in the case of the aforementioned solar cell being a TOPCon cell, the cell also has a back passivation layer 50; as Figures 3 to 4 As shown, in the case of a back-contact solar cell, the cell also has a back passivation layer 51. The back passivation layer suppresses carrier recombination at the interface, thus avoiding the reduction in photocurrent caused by carrier recombination and ensuring high photoelectric conversion efficiency. Optionally, the material of the back passivation layer can be a single-layer or composite film such as alumina, silicon nitride, silicon oxide, and silicon oxynitride. For example, if the back passivation layer is a single-layer film, it can be an alumina single-layer film, a silicon nitride single-layer film, a silicon oxide single-layer film, or a silicon oxynitride single-layer film; if the back passivation layer is a multi-layer film, it can be a composite film of alumina and silicon oxide, or a composite film of alumina, silicon oxide, and silicon nitride. Of course, the material of the back passivation layer in this application is not limited to the above-mentioned materials; those skilled in the art can select any suitable material to form the back passivation layer 50 of this application according to the actual situation. Optionally, the thickness of the back passivation layer in this application can be 70nm~90nm, which can further ensure a reduction in the defect state density on the surface of the solar cell, reduce the probability of electron and hole recombination on the surface, and thus improve the photoelectric conversion efficiency.

[0064] In the above embodiments, such as Figures 1 to 2 As shown, in the case of a TOPCon solar cell, the solar cell also includes a front anti-reflection layer 60; as Figures 3 to 4 As shown, in the case of a back-contact solar cell, the solar cell also includes a front antireflection layer 61. The material of the front antireflection layer can be silicon nitride, silicon dioxide, or aluminum oxide, etc. Furthermore, the front antireflection layer can be a single-layer film or a multi-layer film. When the front antireflection layer is a multi-layer film, it can be formed by alternating deposition of two or more materials with different refractive indices, which can optimize the antireflection effect in multiple wavelength ranges, such as a double-layer SiO2 / SiNx film or a triple-layer SiO2 / SiNx / SiO2 film.

[0065] In the above embodiments, such as Figures 1 to 2 As shown, in the case of a TOPCon solar cell, the solar cell further includes a first electrode 70 and a second electrode 80. The first electrode 70 is located on the side of the first doped conductive layer 30 facing away from the silicon substrate 10, and the second electrode 80 is located on the side of the second doped conductive layer 40 facing away from the silicon substrate 10; Figures 3 to 4 As shown, in the case of a back-contact solar cell, the solar cell further includes a first electrode 71 and a second electrode 81. The first electrode 71 is located on the side of the first doped conductive layer 31 facing away from the silicon substrate 11, and the second electrode 81 is located on the side of the second doped conductive layer 41 facing away from the silicon substrate 11. The materials of the first and second electrodes can be independently selected from copper, silver, nickel, or aluminum. This application does not limit the materials and thicknesses of the first and second electrodes; those skilled in the art can select appropriate materials and thicknesses to form the first and second electrodes according to actual conditions.

[0066] In some embodiments, such as Figures 1 to 2 As shown, the composite passivation layer 20 of the TOPCon solar cell further includes at least one first passivation layer 22, with the AlSiOx layer 21 and the first passivation layer 22 alternately stacked along the first direction X; as Figures 3 to 4 As shown, the composite passivation layer 200 of the back contact solar cell further includes at least one first passivation layer 220, with AlSiOx layers 210 and the first passivation layer 220 alternately stacked along a first direction X. Here, the first direction X is the direction from the second surface to the first surface. The introduction of a first passivation layer into the composite passivation layer creates a sandwich structure with a first passivation layer between adjacent AlSiOx layers. The increased number of passivation structures can better improve the passivation effect.

[0067] In some embodiments, the first passivation layer includes a SiO2 layer. This composite passivation layer forms an AlSiOx / SiO2 / AlSiOx layer structure. The Al-O bonds in the AlSiOx layer attract holes near the silicon substrate, thus moving the holes away from the silicon substrate and reducing their recombination near the silicon substrate, improving the chemical passivation effect. The SiO2 layer has a high dielectric constant, which reduces charge interactions that may occur when multiple AlSiOx layers are in direct contact, preventing a weakening of the passivation effect due to direct contact between multiple AlSiOx layers. Furthermore, the SiO2 layer has high density and purity, which reduces surface dangling bonds and interface defects with the AlSiOx layer, lowering the interface state density, improving the passivation effect, and increasing the battery conversion efficiency.

[0068] Specifically, the thickness of the SiO2 layer can be 1~2 μm, and the thickness of the AlSiOx layer can be 2~3 μm. The battery in this application can also have a multilayer AlSiOx / SiO2 / AlSiOx structure (not limited to). Figures 1 to 4 The diagram illustrates a 1-2 layer AlSiOx / SiO2 / AlSiOx structure, which can further enhance passivation. The thickness of the AlSiOx / SiO2 / AlSiOx layer structure can be 5-7 μm, with 2-6 AlSiOx layers, such as 3, 4, and 5 layers. When the thickness of the SiO2 layer, the thickness of the AlSiOx layer, and the number of AlSiOx layers are within this range, a high passivation effect can be achieved while ensuring that the battery size is not too large.

[0069] In some embodiments, the volumetric content of Al in each AlSiOx layer is independently selected from 5% to 70%, such as 15%, 25%, 35%, 45%, and 55%; the volumetric content of Si is independently selected from 10% to 70%, such as 20%, 30%, 40%, 50%, and 60%. Specifically, in the first direction, increasing the volumetric content of Al can form more Al-O bonds, attracting holes near the silicon substrate and thus moving the holes away from the silicon substrate, reducing their recombination near the silicon substrate, and improving the chemical passivation effect. Decreasing the volumetric content of Si can reduce Si dangling bonds, which is beneficial for reducing the defect state density at the film interface, thereby improving the passivation effect of the battery.

[0070] In some embodiments, the volume content of O in the first passivation layer is 1% to 10%, such as 3%, 5%, 7%, and 9%. Setting the volume content of O in the first passivation layer within the above range can make the first passivation layer more compact, better reduce the interface state density with the AlSiOx layer, reduce dangling bonds and interface defects, and improve the passivation effect.

[0071] In some embodiments, the AlSiOx layer comprises nanoparticles, which may include at least one of the following: TiO2, ZnO, and SiO2. These nanoparticles can further form a composite structure with the AlSiOx layer. The volume content of the nanoparticles in the AlSiOx layer can be 1.8% to 15%, specifically 1.8% to 5.2% when the nanoparticles are TiO2, and 5% to 15% when the nanoparticles are SiO2. This can improve the conductivity of the AlSiOx layer, reduce resistance loss, and improve current transmission efficiency. Furthermore, these nanoparticles can fill voids in the AlSiOx layer, reduce dangling bonds, thereby reducing the interface state density of the AlSiOx layer and improving the photoelectric conversion efficiency of the battery.

[0072] Nanoparticles can also include AlN, HfO2, and GaN. AlN nanoparticles can form a composite film with high charge-trapping capacity with the AlSiOx layer, enhancing the charge-trapping ability of the AlSiOx layer. HfO2 nanoparticles have a higher dielectric constant, improving the passivation effect of the AlSiOx layer. GaN nanoparticles can enhance light scattering and absorption, and their high electron affinity can further improve the electric field passivation effect.

[0073] The technical solutions of this application can be used in photovoltaic cells such as gridless (OBB, Zero Busbar) or multi-busbar (MBB, MULTI-BUSBAR) all-back contact cells, all-back contact cells (IBC, Interdigitated Back Contact), all-back contact solar cells (ABC, All Back Contact), composite passivated back contact cells (HPBC, Hybrid Passivated Back Contact), emitter and rear passivated cells (PERC, Passivated Emitter and Rear Cell), tunneling oxide passivated contact cells (TOPCon, Tunnel Oxide Passivated Contact), TOPCon-IBC (Interdigitated Back Contact, IBC) cells, crystalline silicon heterojunction solar cells (HJT, Heterojunction with Intrinsic Thin-layer), perovskite tandem cells, and flexible cells.

[0074] According to some embodiments of this application, another aspect of this application provides a method for preparing a solar cell, wherein the prepared solar cell, such as... Figure 5 As shown, the preparation method includes:

[0075] Step S1: As Figure 6 As shown, a silicon substrate 11 is provided;

[0076] Specifically, the silicon substrate can be an elemental semiconductor material, a compound semiconductor material, or a sapphire substrate. Specifically, the elemental semiconductor material is composed of a single element, such as silicon. The elemental semiconductor material can be monocrystalline, polycrystalline, amorphous, or microcrystalline (a state simultaneously possessing both monocrystalline and amorphous states is called microcrystalline). For example, silicon can be at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. Compound semiconductor materials include, but are not limited to, silicon germanide, silicon carbide, gallium arsenide, indium gallium dihydrogen phosphate, perovskite, cadmium telluride, and copper indium selenide.

[0077] Step S2: As Figure 6 As shown, a composite passivation layer 200 is formed on one side of a silicon substrate 11 using an atomic layer deposition process. The composite passivation layer 200 includes multiple AlSiOx layers 210, each having Al-O bonds. The AlSiOx layers 210 are prepared using a silicon-containing aluminum precursor source and an oxidant. The aluminum precursor source includes TEA.

[0078] Specifically, the silicon-containing aluminum precursor source can be silicon-containing TEA (triethylaluminum), which is obtained by reacting TEA with silicon-containing haloalkanes. Using silicon-containing TEA introduces Si elements into the composite passivation layer, thereby generating an AlSiOx layer. The Si element improves the interfacial compatibility between the AlSiOx layer and the silicon substrate. The AlSiOx layer also contains Si-O bonds, which enhance the bonding strength between film layers. The oxidant can be ozone (O3). O3's high reactivity allows for the complete oxidation of Al and Si in the film layer, forming Al-O and Si-O bonds, rather than Al-OH bonds, thus reducing hydrogen bonding and improving the film's density.

[0079] Specifically, the aforementioned aluminum precursor source can also be materials such as trimethylaluminum (TMA) or aluminum trichloride, and this application does not impose any specific limitations.

[0080] Specifically, such as Figure 6 As shown, a first passivation layer 220 can also be formed between adjacent AlSiOx layers 210. The first passivation layer 220 can be SiO2. The SiO2 layer has a high dielectric constant, which can reduce the charge interaction that may occur when multiple AlSiOx layers are in direct contact, and avoid the weakening of the passivation effect caused by direct contact between multiple AlSiOx layers.

[0081] The solar cell fabricated using the above-described method has a composite passivation layer comprising multiple AlSiOx layers with Al-O bonds. The shorter bond length of the Al-O bonds allows for smaller distances between adjacent atoms in the AlSiOx layer, enabling the formation of more bonding points within a relatively small space. This results in a denser atomic network within the AlSiOx layer, leading to greater compactness. This increased compactness makes the AlSiOx film more uniform, reduces defects, and improves passivation. The stable structure of the Al-O bonds and the low number of defect energy levels on the AlSiOx layer surface further reduce the interface state density, enhancing the passivation effect of the composite passivation layer. As the Al volume content increases away from the silicon substrate, more Al-O bonds are formed. These bonds attract holes near the silicon substrate, causing them to recede and reducing recombination at the silicon substrate surface, thus enhancing chemical passivation. The AlSiOx layer with a higher Si content near the silicon substrate can adhere more tightly to the silicon substrate, reducing defects between the AlSiOx layer and the silicon substrate. As the Si volume content gradually decreases away from the silicon substrate, Si dangling bonds can be reduced. This helps to reduce the defect state density at the film interface, improve the passivation effect of the cell, and thus improve the conversion efficiency of the cell.

[0082] In some embodiments, the step of preparing the AlSiOx layer includes: introducing a silicon-containing aluminum precursor source into a reaction chamber to form an aluminum-silicon film on one side of a silicon substrate; purging the reaction chamber with an inert gas; and introducing an oxidant into the reaction chamber to react with the aluminum-silicon film to generate the AlSiOx layer. The inert gas can be nitrogen (N2). This process can be repeated until the desired AlSiOx layer thickness is achieved, resulting in a more uniform AlSiOx layer with better film quality.

[0083] In some embodiments, the time for introducing the silicon-containing aluminum precursor source is 0.2~0.55s, the temperature is 180~250°C, the carrier gas flow rate carrying the silicon-containing aluminum precursor source is 50~100 sccm, and the concentration of the oxidant is 100~150 g / m³. 2The oxidant introduction time is 0.3~0.8s, and the reaction pressure between the oxidant and the aluminum-silicon film is 1~5 Torr. The oxidant can be ozone (O3), and the carrier gas carrying the silicon-containing aluminum precursor source can be nitrogen (N2). The introduction time of the silicon-containing aluminum precursor source (silicon-containing TEA pulse) is 0.2~0.55 seconds. The silicon volume content of the silicon-containing TEA used is approximately 5%, and the TEA volume content is approximately 5%. The TEA contains Al, with an Al mass percentage of approximately 25.7%. Different silicon-containing TEA pulse times affect the adsorption amount of silicon-containing TEA on the silicon wafer surface, thus affecting the thickness and composition of the AlSiOx film formed by the reaction with O3. This ensures sufficient time for the silicon-containing TEA to uniformly adhere to the surface, but without excessive duration to prevent unnecessary side reactions. A reaction temperature of 180–250℃ ensures moderate reactivity between the silicon-containing TEA and O3, promoting AlSiOx formation while preventing material decomposition caused by high temperatures. An N2 carrier gas flow rate of 50–100 sccm transports the silicon-containing TEA to the reaction chamber and removes unreacted silicon-containing TEA and byproducts (such as ethane). An O3 concentration of 100–150 g / m³ is used. 3 This provides sufficient oxidizing power to promote AlSiOx deposition. An O3 introduction time of 0.3–0.8 seconds balances the chemical reaction rate, ensuring sufficient reaction while avoiding over-oxidation. A reaction pressure of 1–5 Torr allows for more uniform distribution of reactants under low-pressure conditions, facilitating control of film thickness and quality during preparation.

[0084] In the above embodiments, a precursor source for preparing nanoparticles can also be introduced during the preparation of the AlSiOx layer, so that the final AlSiOx layer is doped with nanoparticles. For example, when the nanoparticles doped in the AlSiOx layer are TiO2, a TiO2 precursor (such as TiCl4 or TiO2 alkoxide) is introduced into the reaction chamber simultaneously with a silicon-containing aluminum precursor source. The flow rate is 4-8 sccm, and the time is 30-50 min, so as to form TiO2 nanoparticles in the AlSiOx layer. Similarly, the precursor source for forming ZnO nanoparticles can be Zn(COD)2 (zinc cyclohexyldione) or Zn(II) acetate; the precursor source for forming SiO2 nanoparticles can be SiCl4 or SiO2 alkoxide. The above-mentioned TiO2 and ZnO materials have high refractive indices, which can enhance light scattering and absorption, and improve the light utilization efficiency of the AlSiOx layer.

[0085] Additionally, nanoparticles can also be introduced into the AlSiOx layer via any of the following methods:

[0086] (a) In-situ generation method: During the deposition of AlSiOx, silicon or aluminum oxide nanoparticles (particle size 5-20nm) are precipitated in situ by controlling the gas ratio of SiH4 / Al(CH3)3 / O2 and plasma power (e.g. 300-500W);

[0087] (b) Pre-doping method: Pre-synthesized SiO2 or Al2O3 nanoparticles (10-50 nm) are dispersed in a precursor solution and co-deposited by spin coating or spray coating;

[0088] (c) Post-processing method: After depositing the AlSiOx layer, phase separation is induced by laser irradiation or rapid annealing (600-800℃, 30-60s) to form nanoparticles.

[0089] This application does not specifically limit the above preparation method. The introduction of nanoparticles significantly improves the overall performance of the AlSiOx layer, such as its light management capability. The nanoparticles enhance light harvesting (especially for 800-1200nm infrared light) through Mie scattering, and the short-circuit current density Jsc of the battery can be increased by 0.5-1.2 mA / cm². 2 Enhanced passivation capability: Nanoparticles form local band bending in the AlSiOx matrix, reducing the interface state density and increasing minority carrier lifetime by 20-50%; Stress modulation capability: Nanoparticles can compensate for the difference in thermal expansion coefficients between AlSiOx and the silicon substrate, reducing the risk of cracking.

[0090] According to some embodiments of this application, another aspect of this application provides a stacked battery, such as... Figure 7 As shown, it includes: a bottom cell 91, which is the solar cell described above, or a solar cell prepared by the method described above; and a top cell 92, located on the bottom cell 91.

[0091] In the above embodiments, the top cell 92 may include: a stacked first transport layer, a perovskite substrate, a second transport layer, a transparent conductive layer, and an antireflection layer. The first transport layer is directly opposite the bottom cell 91. In one example, the back side of the solar cell serving as the bottom cell 91, where a first doped semiconductor layer is disposed, is closer to the first transport layer in the top cell 92; in other words, the top cell 92 is located on the back side of the photovoltaic cell serving as the bottom cell 91.

[0092] In some embodiments, the first transport layer can be either an electron transport layer or a hole transport layer, and the second transport layer can be either an electron transport layer or a hole transport layer. For example, the first transport layer is an electron transport layer and the second transport layer is a hole transport layer, or the first transport layer is a hole transport layer and the second transport layer is an electron transport layer.

[0093] According to some embodiments of this application, another aspect of this application provides a photovoltaic module, such as... Figure 8 As shown, the system includes: a battery string, which is formed by connecting multiple solar cells 100 as described above, or by connecting multiple solar cells 100 prepared by the above-described method, or by connecting multiple stacked cells; an encapsulating film 101 for covering the surface of the battery string; and a cover plate 102 for covering the surface of the encapsulating film 101 facing away from the battery string. The solar cells 100 can be electrically connected to each other via conductive strips 103, which are welded to the electrodes on the solar cells 100.

[0094] The aforementioned encapsulating film can be an organic encapsulating film such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate copolymer (EVA) film, polyvinyl octene elastomer (POE) film, or polyethylene terephthalate (PET) film. Alternatively, at least one of the first or second encapsulating layer can also be an EP film, EPE film, or PVP film. Specifically, EP film refers to a co-extruded film composed of stacked EVA and POE films; EPE film refers to a co-extruded film formed by sequentially stacking EVA, POE, and EVA films; and PVP film refers to a co-extruded film formed by stacking POE, EVA, and POE films. The co-extruded film can be manufactured by sequentially extruding one or more raw materials onto another pre-made film during the film processing, or by bonding different types of pre-made films together.

[0095] The aforementioned cover plate can be a glass cover plate, a plastic cover plate, or other cover plate with light-transmitting function. Specifically, the surface of the cover plate facing the encapsulating film can be an uneven surface or a textured surface containing multiple raised structures, which can increase the utilization rate of incident light.

[0096] The preparation method of the solar cell described above in this application will be specifically described below with reference to specific embodiments and comparative examples.

[0097] Example 1

[0098] This application provides a method for preparing a solar cell, comprising:

[0099] A silicon substrate is provided, which is a silicon wafer with a thickness of 150μm;

[0100] A silicon-containing aluminum precursor source TEA was introduced into the reaction chamber using atomic layer deposition (ALD) to form an aluminum-silicon film on one side of the silicon substrate. The time for introducing the silicon-containing aluminum precursor source TEA was 0.35 s, and the temperature was 220 °C.

[0101] The reaction chamber was purged with inert gas N2 at a flow rate of 80 sccm.

[0102] Ox oxidant O3 was introduced into the reaction chamber and reacted with an aluminum-silicon film to form an AlSiOx layer. The AlSiOx layer has Al-O bonds. The time for introducing the silicon-containing aluminum precursor source TEA was 0.55 s, the temperature was 220 °C, the N2 flow rate was 80 sccm, and the O3 concentration was 120 g / m³. 2 The O3 introduction time is 0.45s, the volume content of Al in the AlSiOx layer is 5%, the volume content of Si is 70%, and the thickness of the AlSiOx layer is 0.8nm.

[0103] SiO2 is deposited on the AlSiOx layer to form a SiO2 layer. The volume content of Si in the SiO2 layer is 1%, and the thickness of the SiO2 layer is 1.5 nm.

[0104] The process of forming an AlSiOx layer was repeated once on the SiO2 layer to form a second AlSiOx layer. During the preparation process, the silicon-containing aluminum precursor source TEA was introduced for 0.55 s at a temperature of 220 °C, with an N2 flow rate of 80 sccm and an O3 concentration of 130 g / m³. 2 The O3 introduction time was 0.35s, the thickness of the second AlSiOx layer was 1.0nm, the volume content of Al was 10%, and the volume content of Si was 60%.

[0105] A first doped conductive layer is formed on the second surface. The doping type is N-type and the thickness is 80 nm.

[0106] A second doped conductive layer is formed in the first region of the first surface. The doping type is P-type and the thickness is 80 nm.

[0107] A first electrode and a second electrode are formed on the side of the first doped conductive layer and the second doped conductive layer away from the silicon substrate, respectively. The material of the first electrode and the second electrode is Ag, and the thickness of each electrode is 10 μm.

[0108] Example 2

[0109] This application provides a method for preparing a solar cell, comprising:

[0110] The difference from Example 1 is that the alternating formation of AlSiOx and SiO2 layers was repeated twice on the AlSiOx layer furthest from the silicon substrate, resulting in four AlSiOx layers. Specifically, during the preparation of the third AlSiOx layer, the silicon-containing aluminum precursor source TEA was introduced for 0.4 s at a temperature of 190°C, with an N2 flow rate of 80 sccm and an O3 concentration of 140 g / m³. 2The O3 introduction time was 0.6 s, the thickness of the third AlSiOx layer was 1.2 nm, the volume content of Al was 35%, and the volume content of Si was 50%. During the preparation of the fourth AlSiOx layer, the silicon-containing aluminum precursor source TEA was introduced for 0.45 s at a temperature of 220 °C, the N2 flow rate was 80 sccm, and the O3 concentration was 150 g / m³. 2 The O3 introduction time was 0.7s, the thickness of the fourth AlSiOx layer was 1.4nm, the volume content of Al was 45%, and the volume content of Si was 40%.

[0111] Example 3

[0112] This application provides a method for preparing a solar cell, comprising:

[0113] The difference from Example 1 is that the alternating formation of AlSiOx and SiO2 layers was repeated four times on the AlSiOx layer furthest from the silicon substrate, resulting in six AlSiOx layers. Specifically, during the preparation of the fifth AlSiOx layer, the silicon-containing aluminum precursor source TEA was introduced for 0.45 s at a temperature of 190°C, with an N2 flow rate of 80 sccm and an O3 concentration of 150 g / m³. 2 The O3 introduction time was 0.65 s, the thickness of the fifth AlSiOx layer was 1.6 nm, the volume content of Al was 55%, and the volume content of Si was 30%. During the preparation of the sixth AlSiOx layer, the silicon-containing aluminum precursor source TEA was introduced for 0.45 s at a temperature of 220 °C, the N2 flow rate was 80 sccm, and the O3 concentration was 150 g / m³. 2 The O3 introduction time was 0.70s, the thickness of the 6th AlSiOx layer was 1.8nm, the volume content of Al was 70%, and the volume content of Si was 10%.

[0114] Example 4

[0115] This application provides a method for preparing a solar cell, comprising:

[0116] The difference from Example 1 is that only the first AlSiOx layer was formed.

[0117] Example 5

[0118] This application provides a method for preparing a solar cell, comprising:

[0119] The difference from Example 1 is that the alternating formation of AlSiOx and SiO2 layers was repeated six times on the AlSiOx layer furthest from the silicon substrate, resulting in eight AlSiOx layers. Specifically, during the preparation of the seventh AlSiOx layer, the silicon-containing aluminum precursor source TEA was introduced for 0.45 s at a temperature of 220°C, with an N2 flow rate of 80 sccm and an O3 concentration of 150 g / m³. 2 The O3 introduction time was 0.75 s, the thickness of the formed 7th AlSiOx layer was 2.0 nm, the volume content of Al was 80%, and the volume content of Si was 8%. During the preparation of the 8th AlSiOx layer, the silicon-containing aluminum precursor source TEA was introduced for 0.45 s at a temperature of 220 °C, the N2 flow rate was 80 sccm, and the O3 concentration was 150 g / m³. 2 The O3 introduction time was 0.8s, the thickness of the 8th AlSiOx layer was 2.2nm, the volume content of Al was 85%, and the volume content of Si was 5%.

[0120] Example 6

[0121] This application provides a method for preparing a solar cell, comprising:

[0122] The difference from Example 2 is that the volume content of Si in the SiO2 layer is 5%.

[0123] Example 7

[0124] This application provides a method for preparing a solar cell, comprising:

[0125] The difference from Example 2 is that the volume content of Si in the SiO2 layer is 10%.

[0126] Example 8

[0127] This application provides a method for preparing a solar cell, comprising:

[0128] The difference from Example 2 is that the volume content of Si in the SiO2 layer is 0.5%.

[0129] Example 9

[0130] This application provides a method for preparing a solar cell, comprising:

[0131] The difference from Example 2 is that the volume content of Si in the SiO2 layer is 13%.

[0132] Example 10

[0133] This application provides a method for preparing a solar cell, comprising:

[0134] The difference from Example 1 is that, in the process of preparing the AlSiOx layer, the TiO2 precursor TiCl4 was introduced into the reaction chamber at a flow rate of 4 sccm for 30 min, and the volume content of TiO2 nanoparticles in the prepared AlSiOx layer was 1.8%~2.0%.

[0135] Example 11

[0136] This application provides a method for preparing a solar cell, comprising:

[0137] The difference from Example 1 is that, in the process of preparing the AlSiOx layer, the TiO2 precursor TiCl4 was introduced into the reaction chamber at a flow rate of 4 sccm for 35 min, and the volume content of TiO2 nanoparticles in the prepared AlSiOx layer was 2.0%~2.4%.

[0138] Example 12

[0139] This application provides a method for preparing a solar cell, comprising:

[0140] The difference from Example 1 is that, in the process of preparing the AlSiOx layer, the TiO2 precursor TiCl4 was introduced into the reaction chamber at a flow rate of 7 sccm for 50 min, and the volume content of TiO2 nanoparticles in the prepared AlSiOx layer was 4.2%~5.2%.

[0141] Comparative Example 1

[0142] A method for preparing a solar cell, comprising:

[0143] The difference from Example 1 is that the passivation structure in the solar cell is a single aluminum oxide layer.

[0144] Comparative Example 2

[0145] A method for preparing a solar cell, comprising:

[0146] The difference from Example 1 is that the AlSiOx layer in the composite passivation layer is replaced with an aluminum oxide layer.

[0147] Comparative Example 3

[0148] A method for preparing a solar cell, comprising:

[0149] The difference from Example 2 is that the AlSiOx layer in the composite passivation layer is replaced with an aluminum oxide layer.

[0150] Comparative Example 4

[0151] A method for preparing a solar cell, comprising:

[0152] The difference from Example 3 is that the AlSiOx layer in the composite passivation layer is replaced with an aluminum oxide layer.

[0153] The performance of solar cells prepared using the methods described in Examples 1-12 and Comparative Examples 1-4 was tested. TOPCon solar cells were used as an example. The test results are shown in Table 1.

[0154] Table 1

[0155]

[0156] As can be seen from the data in Table 1, compared with Comparative Examples 1-4 in the prior art, the interface state density, fill factor, and conversion efficiency of Examples 1-12 proposed in this application are all improved. Therefore, the experimental data shows that the solar cell protected in this application has significant improvements in passivation effect and photoelectric conversion efficiency compared with the prior art.

[0157] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of this application. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A solar cell, characterized in that, include: A silicon substrate having opposing first and second surfaces; A composite passivation layer is located on a first surface of the silicon substrate. The composite passivation layer includes multiple AlSiOx layers, each AlSiOx layer having Al-O bonds. The multiple AlSiOx layers are stacked in a first direction, in which the volume content of Al in the AlSiOx layers increases and the volume content of Si decreases. The first direction is the direction from the second surface to the first surface.

2. The solar cell according to claim 1, characterized in that, The first surface has a first region and a second region alternately arranged along a second direction. The solar cell further includes a first doped conductive layer and a second doped conductive layer, wherein the first doped conductive layer is located on the second surface and has a first doping type; the second doped conductive layer is located in the first region and has a second doping type, and the first doping type is opposite to the second doping type.

3. The solar cell according to claim 1, characterized in that, The second surface has a third region and a fourth region alternately arranged along a second direction. The solar cell further includes a first doped conductive layer and a second doped conductive layer, wherein the first doped conductive layer is located in the fourth region and has a first doping type; the second doped conductive layer is located in the third region and has a second doping type, and the first doping type is opposite to the second doping type.

4. The solar cell according to claim 1, characterized in that, The volumetric content of Al in each AlSiOx layer is independently selected from 5% to 70%, and the volumetric content of Si is independently selected from 10% to 70%.

5. The solar cell according to claim 1, characterized in that, The AlSiOx layer has 2 to 6 layers.

6. The solar cell according to claim 1, characterized in that, The AlSiOx layer contains nanoparticles.

7. The solar cell according to claim 1, characterized in that, The composite passivation layer further includes at least one first passivation layer, wherein the AlSiOx layer and the first passivation layer are alternately stacked along a first direction, the first direction being the direction from the second surface to the first surface.

8. The solar cell according to claim 7, characterized in that, The first passivation layer includes a SiO2 layer.

9. The solar cell according to claim 7, characterized in that, The volume content of O in the first passivation layer is 1% to 10%.

10. A method for preparing a solar cell, characterized in that, The method for preparing a solar cell according to any one of claims 1 to 9 comprises: Provide silicon substrate; A composite passivation layer is formed on one side of the silicon substrate using an atomic layer deposition process. The composite passivation layer includes multiple AlSiOx layers, each AlSiOx layer having Al-O bonds. The AlSiOx layer is prepared using a silicon-containing aluminum precursor source and an oxidant. The aluminum precursor source includes TEA.

11. The preparation method according to claim 10, characterized in that, The steps for preparing the AlSiOx layer include: The silicon-containing aluminum precursor source is introduced into the reaction chamber to form an aluminum-silicon film on one side of the silicon substrate. The reaction chamber was purged with an inert gas; The oxidant is introduced into the reaction chamber and reacts with the aluminum-silicon-containing film to generate the AlSiOx layer.

12. The preparation method according to claim 11, characterized in that, The silicon-containing aluminum precursor source is introduced for 0.2~0.55 s at a temperature of 180~250℃, the carrier gas flow rate carrying the silicon-containing aluminum precursor source is 50~100 sccm, and the concentration of the oxidant is 100~150 g / m³. 2 The oxidant is introduced for 0.3 to 0.8 seconds, and the reaction pressure between the oxidant and the aluminum-silicon film is 1 to 5 Torr.

13. A stacked battery, characterized in that, include: The base cell is a solar cell according to any one of claims 1 to 9, or a solar cell prepared by the method of preparing a solar cell according to any one of claims 10 to 12; The top battery is located on the bottom battery.

14. A photovoltaic module, characterized in that, include: A battery string is formed by connecting multiple solar cells as described in any one of claims 1 to 9, or by connecting multiple solar cells prepared by the method of preparing solar cells as described in any one of claims 10 to 12, or by connecting multiple stacked cells as described in claim 13. An encapsulating film is used to cover the surface of the battery string; A cover plate is used to cover the surface of the encapsulating film that faces away from the battery string.

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