Solar cell and method of manufacturing the same, stacked cell, photovoltaic module

Abstract

The application relates to the photovoltaic field and provides a solar cell, a preparation method of the solar cell, a laminated cell and a photovoltaic module, and at least the performance of the solar cell can be improved. The preparation method of the solar cell comprises the following steps: obtaining a cell substrate, the cell substrate has a preset surface; irradiating the preset surface by using a laser; forming a first aluminum oxide layer, the first aluminum oxide layer is located on the preset surface, and the first aluminum oxide layer contains hydrogen atoms; and forming a second aluminum oxide layer, the second aluminum oxide layer is located on the surface of the first aluminum oxide layer away from the cell substrate, and the second aluminum oxide layer contains hydrogen atoms; wherein the mass percentage of the hydrogen atoms in the first aluminum oxide layer is greater than the mass percentage of the hydrogen atoms in the second aluminum oxide layer; the ratio of the number of oxygen atoms to the number of aluminum atoms in the first aluminum oxide layer is a first ratio, the ratio of the number of oxygen atoms to the number of aluminum atoms in the second aluminum oxide layer is a second ratio, and the second ratio is greater than the first ratio.

Description

Technical Field

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

[0002] As fossil fuels are gradually depleted, solar energy is becoming increasingly widely used as a new energy alternative. A solar cell is a device that converts sunlight into electrical energy. Solar cells utilize the photovoltaic principle to generate charge carriers, which are then extracted using electrodes, thus facilitating the efficient use of electrical energy.

[0003] Solar cells are important devices for converting solar energy into electrical energy, and improving the performance of solar cells is an urgent problem to be solved. Summary of the Invention

[0004] This application provides a solar cell and its preparation method, a tandem cell, and a photovoltaic module, which at least help improve the performance of the solar cell.

[0005] This application provides a method for fabricating a solar cell. The method includes: obtaining a cell substrate having a predetermined surface; irradiating the predetermined surface with a laser; forming a first alumina layer located on the predetermined surface, the first alumina layer containing hydrogen atoms; forming a second alumina layer located on the surface of the first alumina layer away from the cell substrate, the second alumina layer containing hydrogen atoms; wherein the mass percentage of hydrogen atoms in the first alumina layer is greater than the mass percentage of hydrogen atoms in the second alumina layer; the ratio of the number of oxygen atoms to the number of aluminum atoms in the first alumina layer is a first ratio, and the ratio of the number of oxygen atoms to the number of aluminum atoms in the second alumina layer is a second ratio, the second ratio being greater than the first ratio.

[0006] Optionally, the method for forming the first alumina layer includes: performing a first deposition step, the first deposition step including introducing a first aluminum precursor and a first oxygen precursor; performing an ionization step, the ionization step including providing and ionizing a hydrogen-containing gas; wherein the first deposition step and the ionization step are performed cyclically, the flow rate of the hydrogen-containing gas provided in the (n+1)th cycle is less than the flow rate of the hydrogen-containing gas provided in the nth cycle, and n is a positive integer greater than or equal to 1.

[0007] Optionally, the method for forming the second alumina layer includes: cyclically performing a second deposition step, the second deposition step including introducing a second aluminum precursor and a second oxygen precursor; wherein, the gas flow rate of the second oxygen precursor introduced in the (m+1)th cycle is less than the gas flow rate of the second oxygen precursor introduced in the mth cycle, and m is a positive integer greater than or equal to 1.

[0008] Optionally, the method for preparing the solar cell further includes: forming a passivation layer located on the surface of the second alumina layer away from the battery substrate, the passivation layer containing hydrogen atoms; and performing a photothermal annealing process.

[0009] This application also provides a solar cell. The solar cell includes: a battery substrate having a predetermined surface; a first alumina layer located on the predetermined surface, the first alumina layer containing hydrogen atoms; and a second alumina layer located on the surface of the first alumina layer away from the battery substrate, the second alumina layer containing hydrogen atoms; wherein the mass percentage of hydrogen atoms in the first alumina layer is greater than the mass percentage of hydrogen atoms in the second alumina layer; the ratio of the number of oxygen atoms to the number of aluminum atoms in the first alumina layer is a first ratio, and the ratio of the number of oxygen atoms to the number of aluminum atoms in the second alumina layer is a second ratio, the second ratio being greater than the first ratio.

[0010] Optionally, the mass percentage of hydrogen atoms in the first alumina layer is 8% to 12%; the mass percentage of hydrogen atoms in the second alumina layer is 1% to 3%; the first ratio is 1.5 to 1.7; and the second ratio is 1.8 to 1.95.

[0011] Optionally, the first alumina layer includes: a first alumina film located on the preset surface; and a second alumina film located between the first alumina film and the second alumina layer; wherein the mass percentage of hydrogen atoms in the first alumina film is greater than the mass percentage of hydrogen atoms in the second alumina film.

[0012] Optionally, the second alumina layer includes: a first alumina sublayer located on the surface of the first alumina layer; and a second alumina sublayer located on the side of the first alumina sublayer facing away from the preset surface; wherein the ratio of the number of oxygen atoms to the number of aluminum atoms in the first alumina sublayer is a third ratio, and the ratio of the number of oxygen atoms to the number of aluminum atoms in the second alumina sublayer is a fourth ratio, wherein the third ratio is greater than the fourth ratio.

[0013] This application also provides a tandem solar cell. The tandem solar cell includes: a crystalline silicon bottom cell, which is a solar cell prepared by any of the aforementioned methods, or a solar cell prepared by any of the aforementioned methods; and a perovskite top cell, which is located on one side of the bottom cell.

[0014] This application also provides a photovoltaic module. The photovoltaic module includes: a cell string, which is formed by connecting multiple solar cells prepared by any of the above-described methods, or by connecting multiple solar cells prepared by any of the above-described methods, or by connecting multiple stacked cells as described above; an encapsulation layer for covering the surface of the cell string; and a cover plate for covering the surface of the encapsulation layer opposite to the cell string.

[0015] The technical solution provided in this application has at least the following advantages: This application involves laser irradiation of a pre-defined surface. The thermal effect of the laser promotes material recrystallization on the pre-defined surface, repairing some lattice damage and thus improving the performance of the solar cell. Subsequently, a first alumina layer and a second alumina layer are formed sequentially. The mass percentage of hydrogen atoms in the first alumina layer is greater than that in the second alumina layer. The higher hydrogen content in the first alumina layer provides better hydrogen passivation to the pre-defined surface. Furthermore, the first alumina layer's location on the pre-defined surface facilitates the diffusion of hydrogen atoms from it to passivate defects, further enhancing solar cell performance. The second ratio is greater than the first ratio, meaning the second alumina layer contains more oxygen atoms. This provides better field passivation to the pre-defined surface, also contributing to improved solar cell performance. Attached Figure Description

[0016] One or more embodiments are illustrated by way of example with corresponding pictures in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures 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 technology, 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.

[0017] Figure 1 A flowchart illustrating a method for fabricating a solar cell according to an embodiment of this application; Figure 2 This is a schematic diagram of the structure after the formation of the first alumina layer in the method for fabricating a solar cell provided in the embodiments of this application; Figure 3This is a schematic diagram of the structure after the formation of the second alumina layer in the method for fabricating a solar cell provided in the embodiments of this application; Figure 4 This is a schematic diagram of the structure of a solar cell after the passivation layer is formed in the fabrication method of the solar cell provided in the embodiments of this application; Figure 5 A schematic diagram of a solar cell provided in an embodiment of this application; Figure 6 This is a schematic diagram of another structure of the solar cell provided in an embodiment of this application; Figure 7 This is a schematic diagram of a stacked battery provided in an embodiment of this application; Figure 8 This is a schematic diagram of another structure of the stacked battery provided in an embodiment of this application; Figure 9 This is a partial cross-sectional structural diagram of a photovoltaic module provided in an embodiment of this application. Detailed Implementation

[0018] As can be seen from the background technology, the performance of solar cells needs to be improved.

[0019] This application provides a solar cell and its fabrication method, a tandem cell, and a photovoltaic module. In the fabrication method, laser irradiation of a predetermined surface can repair lattice damage, which is beneficial to improving the performance of the solar cell. A first alumina layer with a higher hydrogen content can provide better hydrogen passivation for the predetermined surface, and a second alumina layer with a higher oxygen atom content can provide better field passivation for the predetermined surface, which also helps to improve the performance of the solar cell.

[0020] 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. Similarly, "multiple sets" refers to two or more sets (including two sets), and "multiple pieces" refers to two or more pieces (including two pieces).

[0021] 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.

[0022] 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.

[0023] 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," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of 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. Therefore, they should not be construed as limitations on the embodiments of this application. For example, if the device or element in the illustration is inverted, then the element described as "below," "under," "below," or "bottom" of other elements or features will be oriented "above" or "top" of said other elements or features. Therefore, the term "below" may cover both above and below orientation depending on the context in which the term is used, which will be obvious to those skilled in the art. Materials may be oriented in other ways (e.g., rotated 90 degrees, inverted, flipped), and the spatial relative descriptive terms used herein may be interpreted accordingly.

[0024] In the description of the embodiments of this application, unless otherwise expressly specified and limited, 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.

[0025] In the description of the embodiments of this application, "electrically connected to one component" means that both components are made of conductive materials, and the two components are in direct contact and connected or indirectly connected via other conductive materials. When the photovoltaic module or cell is generating electricity, current flows between the two components. "Electrically contacting one component to another" means that the two components are not only in contact, but also, because both components are made of conductive materials, current flows between the two components when the photovoltaic module or cell is generating electricity.

[0026] In the description of embodiments of this application, the terms "about," "approximately," "roughly," or "about" for a numerical value referring to a specific parameter include the numerical value, and those skilled in the art will understand that the deviation from the numerical value is within the acceptable tolerance of the specific parameter. For example, "about" or "about" for a numerical value may include additional numerical values ​​that are in the range of 90.0% to 110.0% of the numerical value, such as in the range of 95.0% to 105.0%, 97.5% to 102.5%, 99.0% to 101.0%, 99.5% to 100.5%, or 99.9% to 100.1%.

[0027] In the accompanying drawings corresponding to the embodiments of this application, the thickness and / or area of ​​layers, films, panels, regions, etc., are enlarged for better understanding and ease of description. Throughout the specification, the same reference numerals denote the same elements. Furthermore, when describing a component as "generally" formed on another component, it is because the component is not formed on the entire surface of the other component due to manufacturing tolerances or errors.

[0028] In the description of embodiments of this application, when a component "includes" another component, other components are not excluded unless otherwise stated, and may be further included. 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 an intermediate component between the two components. Conversely, when describing a component on the surface of another component, or a component "directly" on another component, or a component surface on which another component is formed or disposed, it indicates that there is no intermediate component between the two components. For simplicity and clarity, various components may be drawn at any scale. In the drawings, some components may be omitted for simplicity.

[0029] 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 term "the component" is also intended to include the plural form unless the context clearly indicates otherwise.

[0030] The “components” mentioned above can refer to layers, membranes, regions, parts, plates, or structures, etc.

[0031] 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.

[0032] Figure 1 This is a flowchart illustrating a method for fabricating a solar cell according to an embodiment of this application. Figure 2 This is a schematic diagram of the structure after the formation of the first alumina layer in the method for fabricating a solar cell provided in this application embodiment. Figure 3 This is a schematic diagram of the structure after the formation of the second alumina layer in the method for preparing a solar cell provided in this application embodiment.

[0033] Reference Figures 1 to 3 The method for preparing a solar cell includes at least the following steps: Step S1: Obtain the battery substrate 10, which has a preset surface 101.

[0034] Step S2: Irradiate the preset surface 101 with a laser.

[0035] Step S3: Reference Figure 2 A first alumina layer 11 is formed, which is located on a preset surface 101 and contains hydrogen atoms.

[0036] Step S4: Reference Figure 3 A second aluminum oxide layer 12 is formed, which is located on the surface of the first aluminum oxide layer 11 away from the battery substrate 10, and contains hydrogen atoms.

[0037] The mass percentage of hydrogen atoms in the first alumina layer 11 is greater than the mass percentage of hydrogen atoms in the second alumina layer 12; the ratio of the number of oxygen atoms to the number of aluminum atoms in the first alumina layer 11 is a first ratio, and the ratio of the number of oxygen atoms to the number of aluminum atoms in the second alumina layer 12 is a second ratio, which is greater than the first ratio.

[0038] The following will describe in more detail the method for preparing photovoltaic modules according to the embodiments of this application, with reference to the accompanying drawings.

[0039] The battery substrate 10 can be one or any combination of TOPCon (Tunnel Oxide Passivated Contact) cells, HJT (Heterojunction with Intrinsic Thin-layer) cells, BC (Back Contact) cells, PERC (Passivated Emitter Rear Cell) cells, thin-film solar cells, and tandem solar cells. Thin-film solar cells include, but are not limited to, perovskite thin-film solar cells, copper indium selenide (CIGS) thin-film solar cells, gallium arsenide (GaAs) thin-film solar cells, and cadmium sulfide (CdS) thin-film solar cells. Tandem solar cells include, but are not limited to, perovskite cells stacked with crystalline silicon cells, perovskite cells stacked with perovskite cells, and perovskite cells stacked with thin-film cells.

[0040] In some embodiments, the battery substrate 10 is a segmented solar cell, which refers to a sub-cell formed by cutting a complete whole cell. The segmented solar cell can be a two-segmented solar cell, a three-segmented solar cell, or a four-segmented solar cell, etc.

[0041] The preset surface 101 is the surface after the cutting process, that is, the preset surface 101 is the cutting surface.

[0042] In some embodiments, the battery substrate 10 has a first surface 102 and a second surface 103 opposite to each other, and a preset surface 101 connects the first surface 102 and the second surface 103.

[0043] In some embodiments, in a solar cell used in a single-glass photovoltaic module, the first side 102 can serve as a light-receiving surface for receiving sunlight, and the second side 103 serves as a backlighting surface. In some embodiments, in a solar cell used in a double-glass module or a bifacial module, both the first side 102 and the second side 103 can serve as light-receiving surfaces and can both be used to receive sunlight. It is understood that the backlighting surface referred to in the embodiments of this application can also receive sunlight, but the degree of sunlight reception is weaker than that of the light-receiving surface, and therefore it is defined as a backlighting surface.

[0044] When a laser irradiates a preset surface 101, the thermal effect of the laser can promote the recrystallization of the material in the preset surface 101 and repair some of the lattice damage in the preset surface 101, thereby improving the performance of the solar cell.

[0045] In some embodiments, ultraviolet laser irradiation may be used.

[0046] In some embodiments, the irradiation time of the laser irradiating the preset surface 101 is 0.1s to 0.5s, for example, 0.1s to 0.2s, 0.2s to 0.4s, or 0.4s to 0.5s. For example, the irradiation time of the laser irradiating the preset surface 101 is 0.1s, 0.2s, 0.3s, 0.4s, or 0.5s.

[0047] In some embodiments, the laser pulse frequency can be 100kHz to 500kHz, such as 100kHz to 200kHz, 200kHz to 300kHz, 300kHz to 400kHz, or 400kHz to 500kHz. For example, the laser pulse frequency can be 100kHz, 150kHz, 200kHz, 250kHz, 300kHz, 350kHz, 400kHz, 450kHz, or 500kHz.

[0048] The first alumina layer 11 is located on the preset surface 101 and can be used to passivate defects on the preset surface 101, thereby improving the performance of the solar cell. In addition, the first alumina layer 11 contains hydrogen atoms, which can migrate to the preset surface 101 and passivate defects during the subsequent photo-annealing process, also contributing to improved solar cell performance. The first alumina layer 11 also protects the solar cell substrate 10 from the influence of external environmental factors such as moisture and oxygen.

[0049] In some embodiments, the method of forming the first alumina layer 11 includes: performing a first deposition step, the first deposition step including introducing a first aluminum precursor and a first oxygen precursor; performing an ionization step, the ionization step including providing and ionizing a hydrogen-containing gas; wherein the first deposition step and the ionization step are performed cyclically. This is beneficial for improving the density of the first alumina layer 11 and improving the passivation effect of the first alumina layer 11.

[0050] In some embodiments, the first alumina layer 11 can be formed by an atomic layer deposition process.

[0051] In some embodiments, the first deposition step may include steps a1, a2, a3, and a4 performed sequentially. Step a1: Introducing a first aluminum precursor; Step a2: Introducing a purge gas; Step a3: Introducing a first oxygen precursor; Step a4: Introducing a purge gas. After performing steps a1, a2, a3, and a4 sequentially (i.e., after completing one first deposition step), an ionization step is then performed.

[0052] Cyclicly performing the first deposition step and the ionization step means performing the first deposition step, then the first ionization step, then the second deposition step, then the second ionization step, and so on, until the last deposition step and the last ionization step. A single cycle is defined as one sequential deposition step and one ionization step.

[0053] In some embodiments, the first aluminum precursor may include trimethylaluminum or aluminum triisopropoxide.

[0054] In some embodiments, the gas flow rate of the first aluminum precursor in a single cycle can be 500 sccm to 1500 sccm, for example, 500 sccm to 800 sccm, 800 sccm to 1200 sccm, or 1200 sccm to 1500 sccm. Exemplarily, the gas flow rate introduced into the first aluminum precursor can be 500 sccm, 650 sccm, 800 sccm, 1000 sccm, 1350 sccm, or 1500 sccm.

[0055] In some embodiments, the introduction time of the first aluminum precursor in a single cycle can be 1s to 5s, for example 1s to 2s, 2s to 3s, 3s to 4s, or 4s to 5s. For example, the introduction time of the first aluminum precursor is 1s, 1.5s, 2s, 2.5s, 3s, 3.5s, 4s, 4.5s, or 5s.

[0056] In some embodiments, the purging gas may be an inert gas, such as nitrogen.

[0057] In some embodiments, the first oxygen precursor may be other oxygen-containing sources such as ozone, oxygen, or water vapor.

[0058] In some embodiments, the gas flow rate of the first oxygen precursor in a single cycle is 1000 sccm to 3000 sccm, for example, 1000 sccm to 1500 sccm, 1500 sccm to 2000 sccm, 2000 sccm to 2500 sccm, or 2500 sccm to 3000 sccm. Exemplarily, the gas flow rate of the first oxygen precursor is 1000 sccm, 1250 sccm, 1500 sccm, 1750 sccm, 2000 sccm, 2250 sccm, 2500 sccm, 2750 sccm, or 3000 sccm.

[0059] In some embodiments, the introduction time of the first oxygen precursor in a single cycle can be 10s to 30s, for example 10s to 15s, 15s to 20s, 20s to 25s, or 25s to 30s. For example, the introduction time of the first oxygen precursor can be 10s, 12.5s, 15s, 17.5s, 20s, 22.5s, 25s, 27.5s, or 30s.

[0060] Hydrogen-containing gases can include hydrogen, ammonia, or silane.

[0061] In some embodiments, the ionization time of hydrogen-containing gas in a single cycle can be 10s to 30s. For example, 10s to 15s, 15s to 20s, 20s to 25s, or 25s to 30s. Exemplarily, the ionization time of hydrogen-containing gas can be 10s, 12.5s, 15s, 17.5s, 20s, 22.5s, 25s, 27.5s, or 30s.

[0062] In some embodiments, the flow rate of hydrogen-containing gas provided in the (n+1)th cycle is less than the flow rate of hydrogen-containing gas provided in the nth cycle, where n is a positive integer greater than or equal to 1. Thus, the formed first alumina layer 11 may include multiple alumina films, the hydrogen content of which gradually decreases from near the preset surface 101 towards away from it. This results in a higher hydrogen content in the portion of the first alumina layer 11 near the preset surface 101, which is beneficial for hydrogen passivation of the preset surface 101. Conversely, a lower hydrogen content in the portion of the first alumina layer 11 away from the preset surface 101 reduces the risk of bubbling and explosion caused by the outward release of a large number of hydrogen atoms from the surface layer of the first alumina layer 11 away from the preset surface 101.

[0063] In some embodiments, during the first cycle, the flow rate of the hydrogen gas can be 1000 sccm to 2000 sccm, for example, 1000 sccm to 1400 sccm, 1400 sccm to 1600 sccm, or 1600 sccm to 2000 sccm. Exemplarily, the flow rate of the hydrogen gas can be 1000 sccm, 1200 sccm, 1400 sccm, 1500 sccm, 1600 sccm, 1800 sccm, or 2000 sccm.

[0064] In some embodiments, the flow rate of hydrogen gas in the last cycle can be 100 sccm to 300 sccm, for example, 100 sccm to 150 sccm, 150 sccm to 200 sccm, 200 sccm to 250 sccm, or 250 sccm to 300 sccm. For example, the flow rate of hydrogen gas can be 100 sccm, 125 sccm, 150 sccm, 175 sccm, 200 sccm, 225 sccm, 250 sccm, 275 sccm, or 300 sccm.

[0065] The number of cycles for the first deposition and ionization steps can be 16 to 20, for example, 16, 17, 18, 19 or 20.

[0066] The second alumina layer 12 has a higher oxygen atom content, which can provide better field passivation effect for the preset surface 101 and also help improve the performance of the solar cell.

[0067] The second alumina layer 12 can be used to passivate defects in the preset surface 101, improving the performance of the solar cell. The second alumina layer 12 contains more oxygen atoms, providing better field passivation for the preset surface 101 and further enhancing solar cell performance. It also contains hydrogen atoms, which can migrate to the preset surface 101 during subsequent photo-annealing processes and passivate defects, also contributing to improved solar cell performance. Furthermore, the second alumina layer 12 protects the solar cell substrate 10 from the influence of external environmental factors such as moisture and oxygen.

[0068] In some embodiments, the method of forming the second alumina layer 12 includes: cyclically performing a second deposition step, the second deposition step including introducing a second aluminum precursor and a second oxygen precursor. The method of forming the second alumina layer 12 can be an atomic layer deposition process, which is beneficial for improving the density of the second alumina layer 12 and enhancing the passivation effect of the first alumina layer 11.

[0069] In some embodiments, the second deposition step may include first introducing a second aluminum precursor, then introducing a purge gas, then introducing a second oxygen precursor, and finally introducing another purge gas.

[0070] In some embodiments, the second deposition step may include steps b1, b2, b3, and b4 performed sequentially. Step b1: Introducing a second aluminum precursor; Step b2: Introducing a purge gas; Step b3: Introducing a second oxygen precursor; Step b4: Introducing a purge gas.

[0071] Cyclic second deposition steps refer to performing a first second deposition step, then a second second deposition step, and so on, until a final second deposition step. A single second deposition step is defined as a single cycle of the second deposition step.

[0072] In some embodiments, the number of cycles in the second deposition step can be 52 to 68, such as 52 to 56, 56 to 60, 60 to 64, or 64 to 68. For example, the number of cycles in the second deposition step can be 52, 54, 56, 58, 60, 62, 64, 66, or 68.

[0073] In some embodiments, the second aluminum precursor may be trimethylaluminum or aluminum triisopropoxide.

[0074] In some embodiments, the gas flow rate of the second aluminum precursor in a single cycle can be 500 sccm to 1500 sccm, for example, 500 sccm to 800 sccm, 800 sccm to 1200 sccm, or 1200 sccm to 1500 sccm. Exemplarily, the gas flow rate introduced into the second aluminum precursor can be 500 sccm, 650 sccm, 800 sccm, 1000 sccm, 1350 sccm, or 1500 sccm.

[0075] In some embodiments, the introduction time of the second aluminum precursor in a single cycle can be 1s to 5s, for example 1s to 2s, 2s to 3s, 3s to 4s, or 4s to 5s. For example, the introduction time of the second aluminum precursor is 1s, 1.5s, 2s, 2.5s, 3s, 3.5s, 4s, 4.5s, or 5s.

[0076] In some embodiments, the second oxygen precursor may include other oxygen-containing sources such as ozone, oxygen, and water vapor.

[0077] In some embodiments, the introduction time of the second oxygen precursor is 5s to 20s, for example 5s to 10s, 10s to 15s, or 15s to 20s. For example, the introduction time of the second oxygen precursor is 5s, 7.5s, 10s, 12.5s, 15s, 17.5s, or 20s.

[0078] In some embodiments, the gas flow rate of the second oxygen precursor introduced in the (m+1)th cycle is less than the gas flow rate of the second oxygen precursor introduced in the mth cycle, where m is a positive integer greater than or equal to 1. Thus, the formed second alumina layer 12 may include multiple alumina sublayers. The oxygen content in these sublayers gradually decreases from near the preset surface 101 towards away from it. This results in a higher oxygen content and a higher density of negative fixed charge in the portion of the second alumina layer 12 near the preset surface 101, which is beneficial for achieving field passivation of the preset surface 101. Furthermore, it enables gradient field passivation of the second alumina layer 12, improving the conversion efficiency of the solar cell. Additionally, it allows for a gradient change in internal stress within the second alumina layer 12, reducing the risk of blistering and cracking after subsequent photothermal annealing or lamination processes, thereby improving the reliability of the solar cell.

[0079] In some embodiments, the second oxygen precursor is an oxygen source that does not contain hydrogen, such as ozone or oxygen. During the formation of the second alumina, hydrogen gas can be ionized to make the second alumina layer 12 contain hydrogen atoms so that the second alumina layer 12 can perform a certain hydrogen passivation effect on the preset surface 101.

[0080] In some embodiments, the second oxygen precursor may include ozone and water vapor. The flow rate of ozone introduced in the (m+1)th cycle is less than the flow rate of ozone introduced in the m-th cycle, and the flow rate of water vapor introduced in the (m+1)th cycle is greater than the flow rate of water vapor introduced in the m-th cycle, where m is a positive integer greater than or equal to 1. Thus, the formed second alumina layer 12 may include multiple alumina sublayers. The oxygen content in the multiple alumina sublayers gradually decreases from near the preset surface 101 to away from the preset surface 101. This results in a higher oxygen content in the portion of the second alumina layer 12 near the preset surface 101, which is beneficial for achieving field passivation of the preset surface 101. Furthermore, it facilitates a gradient change in internal stress within the second alumina layer 12, reducing the risk of blistering and cracking after subsequent photothermal annealing or lamination processes, thereby improving the reliability of the solar cell. Additionally, the inclusion of water vapor in the second oxygen precursor allows the formed second alumina layer 12 to contain hydrogen atoms, which can provide hydrogen passivation.

[0081] In some embodiments, the ozone flow rate introduced in the first cycle can be 2000 sccm to 4000 sccm, for example, 2000 sccm to 2500 sccm, 2500 sccm to 3000 sccm, 3000 sccm to 3500 sccm, or 3500 sccm to 4000 sccm. For example, the ozone flow rate can be 2000 sccm, 2250 sccm, 2500 sccm, 2750 sccm, 3000 sccm, 3250 sccm, 3500 sccm, 3750 sccm, or 4000 sccm.

[0082] In some embodiments, the water vapor flow rate is zero in the first cycle, that is, no water vapor is introduced. As the number of cycles increases, the water vapor flow rate gradually increases and the oxygen flow rate gradually decreases. In this way, the oxygen content in the final formed second alumina layer 12 can gradually decrease from the direction close to the preset surface 101 to the direction away from the preset surface 101.

[0083] In some embodiments, the ozone flow rate introduced in the last cycle can be 500 sccm to 1500 sccm, for example 500 sccm to 800 sccm, 800 sccm to 1200 sccm, or 1200 sccm to 1500 sccm. The ozone flow rate can be 500 sccm, 650 sccm, 800 sccm, 1000 sccm, 1200 sccm, 1350 sccm, or 1500 sccm.

[0084] In some embodiments, the flow rate of water vapor introduced in the last cycle can be 1500 sccm to 2500 sccm, for example, 1500 sccm to 1800 sccm, 1800 sccm to 2200 sccm, or 2200 sccm to 2500 sccm. Exemplarily, the flow rate of water vapor introduced can be 1500 sccm, 1650 sccm, 1800 sccm, 2000 sccm, 2200 sccm, 2350 sccm, 2400 sccm, or 2500 sccm.

[0085] Figure 4 This is a schematic diagram of the structure after the passivation layer is formed in the method for fabricating a solar cell provided in this application embodiment.

[0086] refer to Figure 4In some embodiments, the method for fabricating a solar cell further includes: forming a passivation layer 13, which is located on the surface of the second alumina layer 12 facing away from the solar cell substrate 10, and the passivation layer 13 contains hydrogen atoms; and performing a photothermal annealing process. The passivation layer 13 can passivate the preset surface 101, and the hydrogen atoms in the passivation layer 13 can migrate to the preset surface 101 during the photothermal annealing process, achieving hydrogen passivation, thereby improving the performance of the solar cell. In addition, the passivation layer 13 can protect the solar cell substrate 10, the first alumina layer 11, and the second alumina layer 12 from external environmental corrosion, which is beneficial to improving the reliability of the solar cell.

[0087] The material of the passivation layer 13 may include at least one of silicon oxide, silicon nitride, or silicon oxynitride. In some examples, the passivation layer 13 may be a silicon nitride layer.

[0088] In some embodiments, the process time of the photothermal annealing process is 8 min to 12 min, for example, 8 min to 9 min, 9 min to 10 min, 10 min to 11 min, or 11 min to 12 min. For example, the process time of the photothermal annealing process is 8 min, 8.5 min, 9 min, 9.5 min, 10 min, 10.5 min, 11 min, 11.5 min, or 12 min.

[0089] The process temperature for photothermal annealing is 200℃~240℃, for example 200℃~210℃, 210℃~220℃, 220℃~230℃, or 230℃~240℃. The process temperature for photothermal annealing is 200℃, 205℃, 210℃, 215℃, 220℃, 225℃, 230℃, 235℃, or 240℃.

[0090] The light intensity for photothermal annealing is 800 W / m. 2 ~1200W / m 2 For example, 800W / m 2 ~900W / m 2 900W / m 2 ~1000W / m 2 1000W / m 2 ~1100W / m 2 Or 1100W / m 2 ~1200W / m 2 The light intensity for photothermal annealing is 800 W / m. 2 850W / m 2 900W / m 2 950W / m 2 1000W / m 2 1050W / m 21100W / m 2 1150W / m 2 Or 1200W / m 2 .

[0091] In the method for preparing a solar cell provided in this application, laser irradiation of the preset surface can repair lattice damage to the preset surface, which is beneficial to improving the performance of the solar cell; the first alumina layer with a higher hydrogen content can provide better hydrogen passivation for the preset surface, and the second alumina layer has a higher oxygen atom content, which can provide better field passivation for the preset surface, which is also beneficial to improving the performance of the solar cell.

[0092] Accordingly, another aspect of this application also provides a solar cell. This solar cell can be prepared by the method for preparing a solar cell according to any of the above embodiments. It should be noted that parts that are the same as or corresponding to those in the foregoing embodiments can be referred to the corresponding descriptions in the foregoing embodiments, and will not be repeated hereafter.

[0093] refer to Figure 2 The solar cell includes: a cell substrate 10, a first alumina layer 11, and a second alumina layer 12. The cell substrate 10 has a predetermined surface 101. The first alumina layer 11 is located on the predetermined surface 101 and contains hydrogen atoms. The second alumina layer 12 is located on the surface of the first alumina layer 11 away from the cell substrate 10 and contains hydrogen atoms. The mass percentage of hydrogen atoms in the first alumina layer 11 is greater than the mass percentage of hydrogen atoms in the second alumina layer 12. The ratio of the number of oxygen atoms to the number of aluminum atoms in the first alumina layer 11 is a first ratio, and the ratio of the number of oxygen atoms to the number of aluminum atoms in the second alumina layer 12 is a second ratio, which is greater than the first ratio.

[0094] In some embodiments, the mass percentage of hydrogen atoms in the first alumina layer 11 can be 8% to 12%, for example, 8% to 9%, 9% to 10%, 10% to 11%, or 11% to 12%. The mass percentage of hydrogen atoms in the first alumina layer 11 can be 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, or 12%. When the mass percentage of hydrogen atoms in the first alumina layer 11 is within the above range, the hydrogen content in the first alumina layer 11 is relatively high, which can provide sufficient hydrogen passivation effect for the preset surface 101.

[0095] The mass percentage of hydrogen atoms in the first alumina layer 11 is the average mass percentage of hydrogen atoms in the first alumina layer 11. The mass percentage of hydrogen atoms in the first alumina layer 11 can be measured using techniques such as Elastic Recoil Detection Analysis (ERDA), resonance nuclear reaction analysis, or secondary ion mass spectrometry.

[0096] In some embodiments, the mass percentage of hydrogen atoms in the second alumina layer 12 can be 1% to 3%, for example, 1% to 1.6%, 1.6% to 2.4%, or 2.4% to 3%. The mass percentage of hydrogen atoms in the second alumina layer 12 can be 1%, 1.3%, 1.6%, 2%, 2.4%, 2.7%, or 3%.

[0097] The mass percentage of hydrogen atoms in the second alumina layer 12 is the average mass percentage of hydrogen atoms in the second alumina layer 12. The mass percentage of hydrogen atoms in the second alumina layer 12 can be measured using techniques such as elastic recoil detection analysis (ERDA), resonance nuclear reaction analysis, or secondary ion mass spectrometry.

[0098] The first ratio can be 1.5 to 1.7, for example, 1.5 to 1.56, 1.56 to 1.64, or 1.64 to 1.7. For example, the first ratio can be 1.5, 1.53, 1.56, 1.6, 1.64, 1.67, or 1.7.

[0099] The first ratio can be measured using techniques such as X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, and inductively coupled plasma atomic emission spectroscopy / mass spectrometry.

[0100] The second ratio can be 1.8 to 1.95, for example, 1.8 to 1.85, 1.85 to 1.9, or 1.9 to 1.95. For example, the second ratio can be 1.8, 1.83, 1.85, 1.88, 1.9, 1.93, or 1.95.

[0101] The second ratio can be measured using techniques such as X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, and inductively coupled plasma emission spectroscopy / mass spectrometry.

[0102] In some embodiments, the thickness of the second alumina layer 12 is greater than the thickness of the first alumina layer 11 in a direction perpendicular to the preset surface 101. The thicker second alumina layer 12 can provide better field passivation effect to the cut surface, thereby improving the performance of the solar cell, while the thinner first alumina layer 11 can save on the manufacturing cost of the solar cell.

[0103] In some embodiments, the thickness of the first alumina layer 11 along the direction perpendicular to the preset surface 101 can be 4nm to 6nm, for example, 4nm to 4.6nm, 4.6nm to 5.4nm, or 5.4nm to 6nm. For example, the thickness of the first alumina layer 11 can be 4nm, 4.3nm, 4.6nm, 5nm, 5.4nm, 5.7nm, or 6nm. With the thickness of the first alumina layer 11 within the above range, the first alumina layer 11 can provide sufficient hydrogen passivation to the preset surface 101, and can also avoid resource waste caused by excessive thickness of the first alumina layer 11.

[0104] In some embodiments, the thickness of the second alumina layer 12 along the direction perpendicular to the preset surface 101 is 13nm to 17nm, for example, 13nm to 14nm, 14nm to 15nm, 15nm to 16nm, or 16nm to 17nm. For example, the thickness of the second alumina layer 12 can be 13nm, 13.5nm, 14nm, 14.5nm, 15nm, 15.5nm, 16nm, 16.5nm, or 17nm. When the thickness of the second alumina layer 12 is within the above range, the first alumina layer 11 can provide sufficient field passivation to the preset surface 101, and can also avoid resource waste caused by an excessively large thickness of the second alumina layer 12.

[0105] Figure 5 This is a schematic diagram of a solar cell provided in an embodiment of this application.

[0106] refer to Figure 5 In some embodiments, the first alumina layer 11 includes a first alumina film 111 and a second alumina film 112. The first alumina film 111 is located on a predetermined surface 101; the second alumina film 112 is located between the first alumina film 111 and the second alumina layer 12. The mass percentage of hydrogen atoms in the first alumina film 111 is greater than the mass percentage of hydrogen atoms in the second alumina film 112. The higher hydrogen content of the first alumina film 111, located on the predetermined surface 101, facilitates hydrogen passivation of the predetermined surface 101. The relatively lower hydrogen content in the second alumina film 112 reduces the risk of bubbling and explosion caused by the outward release of a large number of hydrogen atoms from the second alumina film 112.

[0107] In some examples, the first alumina layer 11 may also include a third alumina layer (not shown), the third alumina film being located between the first alumina film 111 and the second alumina film 112, wherein the mass percentage of hydrogen atoms in the first alumina film 111 is greater than the mass percentage of hydrogen atoms in the third alumina film, and the mass percentage of hydrogen atoms in the third alumina film is greater than the mass percentage of hydrogen atoms in the second alumina film 112.

[0108] In some embodiments, the first alumina layer 11 may include multiple alumina films, such as 4, 5, 6, or 7 layers, and the hydrogen content of the alumina film near the preset surface 101 is greater than the hydrogen content of the adjacent alumina film away from the preset surface 101. That is, the hydrogen content in the multiple alumina films gradually decreases from the direction near the preset surface 101 to the direction away from the preset surface 101, so that the hydrogen content of the part of the first alumina layer 11 near the preset surface 101 is higher, which is beneficial to hydrogen passivation of the preset surface 101. The hydrogen content of the part of the first alumina layer 11 away from the preset surface 101 is lower, which can reduce the risk of bubbling and explosion of the film caused by the outward release of a large number of hydrogen atoms on the surface of the first alumina layer 11 away from the preset surface 101.

[0109] Figure 6 This is a schematic diagram of another structure of the solar cell provided in an embodiment of this application.

[0110] In some embodiments, the second alumina layer 12 includes a first alumina sublayer 121 and a second alumina sublayer 122. The first alumina sublayer 121 is located on the surface of the first alumina layer 11; the second alumina sublayer 122 is located on the side of the first alumina sublayer 121 facing away from the preset surface 101. The ratio of oxygen atoms to aluminum atoms in the first alumina sublayer 121 is a third ratio, and the ratio of oxygen atoms to aluminum atoms in the second alumina sublayer 122 is a fourth ratio, with the third ratio being greater than the fourth ratio. Thus, the first alumina sublayer 121, which is closer to the preset surface 101, has a higher oxygen content and a higher density of negative fixed charge, which is beneficial for achieving field passivation of the preset surface 101. The second alumina sublayer 122 has a relatively higher aluminum content and is more dense, which is beneficial for protecting the first alumina sublayer 121, the first alumina layer 11, and the battery substrate 10 from external environmental corrosion.

[0111] In some examples, the second alumina layer 12 includes a third alumina sublayer (not shown), which is located between the first alumina sublayer 121 and the second alumina sublayer 122; wherein the ratio of the number of oxygen atoms to the number of aluminum atoms in the third alumina sublayer is a fifth ratio, which is less than the third ratio and greater than the fourth ratio.

[0112] In some embodiments, the ratio of the number of oxygen atoms to the number of aluminum atoms is simply referred to as the oxygen-aluminum ratio. The second alumina layer 12 includes multiple alumina sublayers, such as 4, 5, 6, or 7 layers. The oxygen-aluminum ratio of the alumina sublayers near the preset surface 101 is greater than that of the adjacent alumina sublayers away from the preset surface 101. That is, the oxygen content in the second alumina layer 12 gradually decreases from the direction near the preset surface 101 to the direction away from the preset surface 101. On the one hand, this makes the oxygen content in the part of the second alumina layer 12 near the preset surface 101 higher, with a higher density of negative fixed charge, which is beneficial for achieving field passivation of the preset surface 101. On the other hand, it can achieve gradient field passivation of the second alumina layer 12, which can improve the conversion efficiency of the solar cell. Furthermore, it is beneficial for the internal stress in the second alumina layer 12 to change in a gradient, which can reduce the risk of problems such as film blistering and cracking after subsequent photothermal annealing or lamination processes, thereby improving the reliability of the solar cell.

[0113] refer to Figure 4 In some embodiments, the solar cell further includes a passivation layer 13, which is located on the surface of the second alumina layer 12 facing away from the solar cell substrate 10. The passivation layer 13 contains hydrogen atoms. The passivation layer 13 can passivate the predetermined surface 101, and the hydrogen atoms in the passivation layer 13 also have a hydrogen passivation effect, thereby improving the performance of the solar cell. The passivation layer 13 can also protect the solar cell substrate 10, the first alumina layer 11, and the second alumina layer 12 from external environmental corrosion, which is beneficial to improving the reliability of the solar cell.

[0114] In the solar cell provided above, the mass percentage of hydrogen atoms in the first alumina layer 11 is greater than that in the second alumina layer 12. The higher hydrogen content in the first alumina layer 11 provides better hydrogen passivation to the preset surface 101. Furthermore, the location of the first alumina layer 11 on the preset surface 101 facilitates the diffusion of hydrogen atoms from the first alumina layer 11 into the cell substrate 10, thus passivating the cell substrate 10 and improving the performance of the solar cell. The second ratio is greater than the first ratio, meaning the second alumina layer 12 contains more oxygen atoms. The second alumina layer 12 provides better field passivation to the preset surface 101, also contributing to improved solar cell performance.

[0115] Accordingly, another aspect of this application also provides a tandem solar cell. The tandem solar cell includes a solar cell prepared by any of the above-described solar cells or by the method for preparing a solar cell described in any of the above embodiments. It should be noted that parts that are the same as or corresponding to those in the foregoing embodiments can be referred to the corresponding descriptions in the foregoing embodiments, and will not be repeated hereafter.

[0116] Figure 7This is a schematic diagram of a stacked battery provided in an embodiment of this application.

[0117] refer to Figure 7 The tandem solar cell includes a crystalline silicon bottom cell 20 and a perovskite top cell 21. The crystalline silicon bottom cell 20 is a solar cell prepared by the method for preparing solar cells in any of the preceding embodiments, or the crystalline silicon bottom cell 20 is a solar cell in any of the preceding embodiments; the perovskite top cell 21 is located on one side of the crystalline silicon bottom cell 20.

[0118] Figure 8 This is a schematic diagram of another structure of the stacked battery provided in the embodiments of this application.

[0119] refer to Figure 8 In some embodiments, the perovskite top solar cell 21 may include: a first transport layer 211, a perovskite functional layer 212, a second transport layer 213, a transparent conductive layer 214, and an anti-reflection layer 215 stacked together. The first transport layer 211 is directly opposite the crystalline silicon bottom solar cell 20.

[0120] In some examples, the first transport layer 211 can be one of an electron transport layer and a hole transport layer, and the second transport layer 213 can be the other of an electron transport layer and a hole transport layer.

[0121] In some embodiments, the bandgap width of the perovskite top cell 21 is greater than that of the crystalline silicon bottom cell 20. Therefore, stacking the perovskite top cell 21 on top of the crystalline silicon bottom cell 20 can give the stacked cell a wider spectral response range, thereby maximizing the utilization of solar energy and improving the efficiency of the cell.

[0122] In some embodiments, the tandem solar cell may further include an intermediate connecting layer (not shown), which is located between the crystalline silicon bottom cell 20 and the perovskite top cell 21 for electrically connecting the crystalline silicon bottom cell 20 and the perovskite top cell 21.

[0123] In some embodiments, the intermediate connection layer is generally a tunnel junction or a very thin metal or transparent electrode composite layer. Optionally, the intermediate connection layer can be a transparent conductive oxide, which has good optoelectronic properties, high photon transmittance and high conductivity, thereby enabling the perovskite top cell 21 and the crystalline silicon bottom cell 20 to maintain good ohmic contact.

[0124] In some embodiments, the tandem solar cells can be configured as a 2T (two-terminal series / two-terminal stacked) structure or a 4T (four-terminal series / four-terminal stacked) structure. The tandem solar cells can also be configured as a 3T (three-terminal series / three-terminal stacked) structure. The three-terminal stacked structure is mainly used in tandem solar cells manufactured by combining solar cells with perovskite top cells, and it produces three electrodes. In the four-terminal tandem solar cell, the two sub-cells are manufactured independently, and they are only optically connected; their circuits are independent. It can be understood that the perovskite top cell 21 and the crystalline silicon bottom cell 20 are merely physically stacked, and in reality, they each output independently. Therefore, the four-terminal tandem solar cell has two positive electrodes and two negative electrodes.

[0125] Accordingly, in another aspect, this application also provides a photovoltaic module, which includes the solar cell described in any of the above embodiments, or a solar cell prepared by the method described in any of the above embodiments, or a tandem cell described in the above embodiments. It should be noted that the parts that are the same as or corresponding to the foregoing embodiments can be referred to the corresponding descriptions of the foregoing embodiments, and will not be repeated below.

[0126] Figure 9 This is a partial cross-sectional structural diagram of a photovoltaic module provided in an embodiment of this application. Figure 9 The TOPCon cell is used as an example, with solar cells as an example.

[0127] refer to Figure 9 The photovoltaic module includes: a battery string, which is formed by connecting multiple solar cells 30 prepared by any of the above-described methods, or by connecting multiple solar cells 30 prepared by any of the above-described methods, or by connecting multiple stacked cells as described above; an encapsulation layer 31 for covering the surface of the battery string; and a cover plate 32 for covering the surface of the encapsulation layer 31 facing away from the battery string.

[0128] Multiple solar cells 30 can be electrically connected through solder strips 33.

[0129] In some embodiments, the encapsulation layer 31 includes a first encapsulation sublayer and a second encapsulation sublayer. The first encapsulation sublayer covers one of the front and back sides of the solar cell 30, and the second encapsulation sublayer covers the other of the front and back sides of the solar cell 30. Specifically, at least one of the first and second encapsulation sublayers can be an organic encapsulation layer such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate copolymer (EVA) film, polyvinyl octene coelastomer (POE) film, or polyethylene terephthalate (PET) film. Alternatively, at least one of the first and second encapsulation sublayers can also be an EP film, EPE film, or PEP film. Among them, EP film refers to a co-extruded film composed of stacked EVA film and POE film; EPE film refers to a co-extruded film formed by sequentially stacking EVA film, POE film, and EVA film; and PEP film refers to a co-extruded film formed by stacking POE film, EVA film, and POE film. Co-extruded films can be prepared 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.

[0130] In some cases, the first encapsulation sublayer and the second encapsulation sublayer still have a boundary line before lamination. After lamination, the photovoltaic module will no longer have the concept of the first encapsulation sublayer and the second encapsulation sublayer. That is, the first encapsulation sublayer and the second encapsulation sublayer have formed an integral encapsulation layer 31.

[0131] In some embodiments, the cover plate 32 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 32 facing the encapsulation layer 31 can be an uneven surface or a textured surface containing multiple raised structures, thereby increasing the utilization rate of incident light. The cover plate 32 may include a first cover plate and a second cover plate, the first cover plate being opposite to the first encapsulation sublayer, and the second cover plate being opposite to the second encapsulation sublayer.

[0132] 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 method for preparing a solar cell, characterized in that, include: A battery substrate is obtained, the battery substrate having a predetermined surface; The preset surface is irradiated with a laser; A first alumina layer is formed, the first alumina layer is located on the preset surface, and the first alumina layer contains hydrogen atoms; A second aluminum oxide layer is formed, which is located on the surface of the first aluminum oxide layer away from the battery substrate, and the second aluminum oxide layer contains hydrogen atoms. Wherein, the mass percentage of hydrogen atoms in the first alumina layer is greater than the mass percentage of hydrogen atoms in the second alumina layer; the ratio of the number of oxygen atoms to the number of aluminum atoms in the first alumina layer is a first ratio, and the ratio of the number of oxygen atoms to the number of aluminum atoms in the second alumina layer is a second ratio, the second ratio being greater than the first ratio.

2. The method for preparing a solar cell according to claim 1, characterized in that, The method for forming the first alumina layer includes: A first deposition step is performed, the first deposition step including the introduction of a first aluminum precursor and a first oxygen precursor; An ionization step is performed, the ionization step including providing and ionizing a hydrogen-containing gas; The first deposition step and the ionization step are performed cyclically. The flow rate of the hydrogen-containing gas provided in the (n+1)th cycle is less than the flow rate of the hydrogen-containing gas provided in the nth cycle, where n is a positive integer greater than or equal to 1.

3. The method for preparing a solar cell according to claim 1, characterized in that, The method for forming the second alumina layer includes: The second deposition step is repeated, and the second deposition step includes introducing a second aluminum precursor and a second oxygen precursor. Wherein, the gas flow rate of the second oxygen precursor introduced in the (m+1)th cycle is less than the gas flow rate of the second oxygen precursor introduced in the mth cycle, and m is a positive integer greater than or equal to 1.

4. The method for preparing a solar cell according to any one of claims 1 to 3, characterized in that, The method for preparing the solar cell further includes: A passivation layer is formed, the passivation layer being located on the surface of the second alumina layer opposite to the battery substrate, and the passivation layer containing hydrogen atoms; Perform photothermal annealing process.

5. A solar cell, characterized in that, include: A battery substrate, wherein the battery substrate has a predetermined surface; A first alumina layer is located on the preset surface and contains hydrogen atoms. A second alumina layer is located on the surface of the first alumina layer away from the battery substrate, and the second alumina layer contains hydrogen atoms. Wherein, the mass percentage of hydrogen atoms in the first alumina layer is greater than the mass percentage of hydrogen atoms in the second alumina layer; the ratio of the number of oxygen atoms to the number of aluminum atoms in the first alumina layer is a first ratio, and the ratio of the number of oxygen atoms to the number of aluminum atoms in the second alumina layer is a second ratio, the second ratio being greater than the first ratio.

6. The solar cell according to claim 5, characterized in that, The mass percentage of hydrogen atoms in the first alumina layer is 8% to 12%; the mass percentage of hydrogen atoms in the second alumina layer is 1% to 3%; the first ratio is 1.5 to 1.7; and the second ratio is 1.8 to 1.

95.

7. The solar cell according to claim 5, characterized in that, The first alumina layer includes: A first alumina film is located on the preset surface; A second alumina film is located between the first alumina film and the second alumina layer; The mass percentage of hydrogen atoms in the first alumina film is greater than the mass percentage of hydrogen atoms in the second alumina film.

8. The solar cell according to claim 5, characterized in that, The second alumina layer includes: The first alumina sublayer is located on the surface of the first alumina layer; The second alumina sublayer is located on the side of the first alumina sublayer that is away from the preset surface; The ratio of oxygen atoms to aluminum atoms in the first alumina sublayer is a third ratio, and the ratio of oxygen atoms to aluminum atoms in the second alumina sublayer is a fourth ratio, wherein the third ratio is greater than the fourth ratio.

9. A stacked battery, characterized in that, include: A crystalline silicon bottom cell, wherein the crystalline silicon bottom cell is a solar cell prepared by the method of preparing a solar cell as described in any one of claims 1 to 4, or a solar cell as described in any one of claims 5 to 8; A perovskite top cell, wherein the perovskite top cell is located on one side of the crystalline silicon bottom cell.

10. A photovoltaic module, characterized in that, include: A battery string is formed by connecting multiple solar cells prepared by the method of any one of claims 1 to 4, or by connecting multiple solar cells as described in claims 5 to 8, or by connecting multiple stacked cells as described in claim 9. An encapsulation layer that covers the surface of the battery string; A cover plate that covers the surface of the encapsulation layer opposite to the battery string.

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