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

Abstract

The application relates to the photovoltaic technology field, and provides a solar cell, a preparation method of the solar cell, a laminated cell and a photovoltaic module, which can at least improve the performance of the solar cell and improve the standing decay problem. The preparation method of the solar cell comprises the following steps: providing a cell body, the cell body comprising a substrate, a functional layer and a grid electrode, the functional layer being located on the substrate, and at least part of the grid electrode being located on the functional layer; and performing a light annealing process on the cell body, the light annealing process being performed in an atmosphere of a passivation gas, the passivation gas comprising a halogen source gas, and halogen elements in the halogen source gas being diffused into the substrate in the step of the light annealing process.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, 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 crucial devices for converting solar energy into electrical energy. However, current solar cell manufacturing processes have certain limitations, leading to significant degradation issues when solar cells are left to stand still. 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 solar cells and mitigate the problem of static degradation.

[0005] This application provides a method for fabricating a solar cell, the method comprising: providing a cell body, the cell body including a substrate, a functional layer and grid electrodes, the functional layer being located on the substrate, and at least a portion of the grid electrodes being located on the functional layer; performing a photo-annealing process on the cell body, the photo-annealing process being performed in a passivating gas atmosphere, the passivating gas including a halogen source gas, wherein halogen elements in the halogen source gas diffuse into the substrate during the photo-annealing process.

[0006] Optionally, the halogen element includes at least one of fluorine, chlorine, bromine, and iodine.

[0007] Optionally, the halogen element includes at least fluorine.

[0008] Optionally, the passivation gas may further include a hydrogen source gas, wherein the hydrogen element in the hydrogen source gas diffuses into the substrate during the photo-annealing process.

[0009] Optionally, the ratio of the flow rate of the halogen source gas to the flow rate of the hydrogen source gas is 5 to 9.

[0010] Optionally, the flow rate of the halogen source gas is 1000 sccm to 5000 sccm; the flow rate of the hydrogen source gas is 500 sccm to 1000 sccm.

[0011] Optionally, the process temperature of the light annealing process is 300℃~1000℃; the light intensity of the light annealing process is 100mW / cm². 2 ~10000mW / cm 2 The pressure of the optical annealing process is 100 mbar to 3000 mbar; the process time of the optical annealing process is 20 min to 35 min; and the flow rate of the passivation gas is 1000 sccm to 6000 sccm.

[0012] Optionally, the photoannealing process includes: a heating step, wherein the heating step heats the battery body to a target temperature; and a photoirradiation step, wherein light energy is provided to the heated battery body, wherein at least the passivation gas is provided in the photoirradiation step.

[0013] This application also provides a solar cell, which is prepared by any of the aforementioned methods for preparing a solar cell. The solar cell includes: a substrate; a functional layer located on the substrate; a grid electrode located on the functional layer; and a halogen element located within the surface of the substrate.

[0014] Optionally, the halogen element includes at least one of fluorine, chlorine, bromine, and iodine.

[0015] Optionally, the concentration of the halogen element is 1E3atom / cm³. 3 ~1E5atom / cm 3 .

[0016] This application also provides a tandem solar cell, comprising: a base 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 cell located on one side of the base cell.

[0017] This application also provides a photovoltaic module, comprising: a battery string, which is formed by connecting multiple solar cells prepared by any of the aforementioned methods, or by connecting multiple of the aforementioned solar cells, or by connecting multiple of the aforementioned 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.

[0018] The technical solution provided in this application has at least the following advantages:

[0019] In the fabrication of solar cells, the photo-annealing process of the cell body is carried out in a passivating gas atmosphere, including a halogen source gas. During the photo-annealing process, halogen elements in the halogen source gas diffuse from the substrate surface into the substrate, passivating defects on the substrate surface and within the substrate, thereby improving the performance of the solar cell. Furthermore, using halogen elements to passivate substrate defects can also form more stable chemical bonds, which is beneficial for mitigating the static degradation problem of solar cells. Attached Figure Description

[0020] 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.

[0021] Figure 1 A flowchart illustrating a method for fabricating a solar cell according to an embodiment of this application;

[0022] Figure 2 A schematic diagram of a solar cell provided in an embodiment of this application;

[0023] Figure 3 This is a schematic diagram of another structure of the solar cell provided in an embodiment of this application;

[0024] Figure 4 This is a schematic diagram of a stacked battery provided in an embodiment of this application;

[0025] Figure 5 This is a schematic diagram of a photovoltaic module provided in an embodiment of this application.

[0026] Explanation of reference numerals in the attached figures:

[0027] 10. Substrate; 101. First surface; 102. Second surface; 11. Functional layer; 12. Grid line electrode; 20. Bottom cell; 21. Perovskite cell; 30. Solar cell; 31. Encapsulating film; 32. Cover plate; 33. Solder ribbon. Detailed Implementation

[0028] A method for fabricating a solar cell in related technologies includes: providing a cell body; and performing a photo-annealing process on the cell body in an inert gas atmosphere. The cell body includes a substrate, a functional layer, and grid electrodes, wherein the functional layer is located on the substrate, and at least a portion of the grid electrodes are located on the functional layer.

[0029] The photo-annealing process in related technologies is carried out in an inert atmosphere. It mainly passesivates the defects of the substrate by exciting hydrogen elements in the functional layer to move to the substrate. The passivation source of the substrate mainly comes from the hydrogen elements in the functional layer. The passivation source is limited, which limits the improvement effect of solar cells.

[0030] Furthermore, research has revealed a significant issue of static decay during photoannealing in an inert gas atmosphere. This static decay is likely caused by the photogenerated carriers and their recombination energy generated during photoannealing, which disrupt some Si-Si bonds in the substrate. This leads to recombination between Si and H bonds, forming a new metastable conformation. While this metastable conformation can passivate the substrate, it cannot be maintained long-term and will slowly revert to its initial thermodynamically stable conformation. Therefore, while photoannealing can improve efficiency, this improvement is not sustainable.

[0031] In other words, the cause of static degradation may be that during the photo-annealing process of the relevant technology, an unstable chemical bond is formed when hydrogen passesivates the substrate. Over time, the unstable chemical bond is broken, meaning that the hydrogen element is unable to passivate substrate defects, thus causing the performance of the solar cell to deteriorate and resulting in a relatively obvious static degradation problem.

[0032] Therefore, the performance of solar cells in related technologies needs to be improved, and the problem of static degradation needs to be addressed.

[0033] Therefore, this application proposes a solar cell, its fabrication method, a tandem solar cell, and a photovoltaic module. In the solar cell fabrication method, the photo-annealing process of the cell body is carried out in a passivating gas atmosphere. The passivating gas includes a halogen source gas. During the photo-annealing process, halogen elements in the halogen source gas diffuse from the substrate surface into the substrate, passivating surface and internal defects of the substrate, thereby improving the performance of the solar cell. Furthermore, using halogen elements to passivate substrate defects can also form more stable chemical bonds, which is beneficial for improving the static degradation problem of solar cells.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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).

[0038] 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.

[0039] 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.

[0040] 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 connected via other conductive materials. Therefore, when the photovoltaic module is generating electricity, there is current transfer 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, there is current transfer between the two components when the photovoltaic module is generating electricity.

[0041] 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. It should be understood that 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. Furthermore, when describing a component as "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 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.

[0044] 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 a solar cell provided in an embodiment of this application.

[0045] refer to Figure 1 and Figure 2 The method for fabricating a solar cell includes: step S100, providing a cell body, the cell body including a substrate 10, a functional layer 11 and a grid electrode 12, the functional layer 11 being located on the substrate 10, and at least a portion of the grid electrode 12 being located on the functional layer 11; step S101, performing a photo-annealing process on the cell body, the photo-annealing process being performed in an atmosphere of passivation gas, the passivation gas including a halogen source gas, the halogen element in the halogen source gas diffusing into the substrate 10 during the photo-annealing process.

[0046] Solar cells are used to convert solar energy into electrical energy.

[0047] Solar cells can be one or any combination of PERC (Passivated Emitter Rear Cell), BC (Back Contact), TOPCON (Tunnel Oxide Passivated Contact), heterojunction cells, thin-film solar cells, and tandem 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 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.

[0048] Solar cells can be either whole cells or segmented cells. A segmented solar cell refers to a cell formed by cutting a single, whole cell. Segmented cells can be divided into two-segmented cells, three-segmented cells, or four-segmented cells, etc.

[0049] Solar cells can be obtained by photo-annealing the cell body.

[0050] The substrate 10 is used to receive sunlight and generate photogenerated carriers.

[0051] In some embodiments, the substrate 10 may include silicon. During the photo-annealing process, halogens in the passivation gas can form silicon halide bonds with silicon to passivate defects on the surface and within the substrate 10, thereby improving the performance of the solar cell.

[0052] In some embodiments, substrate 10 may be a semiconductor substrate.

[0053] In some embodiments, the material of the substrate 10 may be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon or germanium. The elemental semiconductor material may be monocrystalline, polycrystalline, amorphous, or microcrystalline (a state simultaneously possessing both monocrystalline and amorphous states is called microcrystalline). For example, silicon may be at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, and microcrystalline silicon.

[0054] In some embodiments, the substrate 10 may also be a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, silicon germanide, silicon carbide, gallium arsenide, indium gallium arsenide, perovskite, cadmium telluride, copper indium selenide, etc.

[0055] The substrate 10 can also be a sapphire substrate, a silicon substrate on an insulator, or a germanium substrate on an insulator.

[0056] The substrate 10 can be an N-type semiconductor substrate or a P-type semiconductor substrate. The N-type semiconductor substrate is doped with an N-type 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 semiconductor substrate is doped with a P-type element, which can be at least one of group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0057] The substrate 10 has a first surface 101 and a second surface 102 facing each other. In some embodiments, the solar cell used in a single-glass photovoltaic module is considered a single-sided cell, in which case the first surface 101 can serve as the light-receiving surface for receiving sunlight, and the second surface 102 serves as the backlight surface. In some embodiments, the solar cell used in a double-glass module or a bifacial module is considered a bifacial cell, in which case both the first surface 101 and the second surface 102 can serve as light-receiving surfaces and can both be used to receive sunlight. It is understood that the backlight 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 backlight surface.

[0058] In some embodiments, at least one of the first surface 101 and the second surface 102 may be a velvety surface, such as a pyramidal velvet surface, which can enhance the absorption and utilization rate of light by the substrate 10.

[0059] The functional layer 11 includes at least one of a passivation film and an antireflection film. The passivation film can passivate the substrate 10, reduce the defect state density of the substrate 10, and effectively suppress carrier recombination in the substrate 10. The antireflection film can effectively reduce reflection of incident light by the substrate 10 and improve the utilization rate of incident light by the substrate 10. For those skilled in the art, the passivation film or the antireflection film can be made of similar materials and used for passivation or optical modulation.

[0060] In some embodiments, the functional layer 11 includes hydrogen, i.e., the functional layer 11 is a hydrogen-containing functional layer. During photo-annealing, the photo-annealing process provides energy to the hydrogen in the functional layer 11, exciting the hydrogen in the functional layer 11 to migrate to the substrate 10 to passivate defects in the substrate 10. This can improve the performance of the solar cell.

[0061] The hydrogen element can originate from residual hydrogen produced during the formation of functional layer 11. Taking a silicon nitride layer as an example, during plasma-enhanced chemical vapor deposition (PECVD) to form the silicon nitride layer, hydrogen-containing precursors such as silane and ammonia are introduced. Under the influence of plasma, hydrogen elements are embedded in the silicon nitride lattice in the form of silicon-hydrogen bonds and nitrogen-hydrogen bonds. Taking an alumina layer as an example, during atomic layer deposition (ALD) to form the alumina layer, the reaction between the precursor (such as trimethylaluminum) and the reactant gas (such as water) leaves residual hydroxyl groups and aluminum-hydrogen bonds in the alumina layer. The hydrogen element can also originate from an additional hydrogen source provided during the formation of functional layer 11.

[0062] The material of the functional layer 11 can be at least one of silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride, and transparent conductive materials (such as indium tin oxide).

[0063] In some embodiments, functional layer 11 may be a single-layer structure. In some embodiments, functional layer 11 may also be a multi-layer structure, wherein the materials of each layer in the multi-layer structure may be different from each other, or, a portion of the layers may be made of different materials, while the remaining portion may be made of the same material. For example, functional layer 11 may be a multi-layer structure comprising a silicon nitride layer and an aluminum oxide layer.

[0064] In some embodiments, the solar cell further includes a doped semiconductor portion (not shown). The doped semiconductor portion may be part of the substrate 10 and located within the substrate 10 on the side close to the functional layer 11. Alternatively, the doped semiconductor portion may not be part of the substrate 10, in which case the doped semiconductor portion is located between the substrate 10 and the functional layer 11, and the doped semiconductor portion is used to guide charge carriers to the gate electrode 12.

[0065] The gate electrode 12 is electrically connected to the doped semiconductor section for collecting charge carriers.

[0066] In some embodiments, at least a portion of the gate electrode 12 is in electrical contact with the doped semiconductor portion. During the photo-annealing process, some halogen elements diffuse to the contact interface between the gate electrode 12 and the doped semiconductor portion. The halogen elements can also passivate defects at the contact interface between the gate electrode 12 and the doped semiconductor portion, improving the metal contact performance between the gate electrode 12 and the doped semiconductor portion, thereby also improving the performance of the solar cell.

[0067] At least a portion of the gate electrode 12 is located on the functional layer 11. For the gate electrode 12 formed by high-temperature metallization process, a portion of the gate electrode 12 will penetrate the functional layer 11 and contact the doped semiconductor portion; for the gate electrode 12 formed by low-temperature metallization process, the gate electrode 12 will not penetrate the functional layer 11.

[0068] Figure 3 This is a schematic diagram of another structure of a solar cell provided in an embodiment of this application.

[0069] like Figure 2 As shown, in some cases, such as when the solar cell is a TOPCON cell, both the first surface 101 and the second surface 102 of the substrate 10 have grid electrodes 12. Figure 3 As shown, in other cases, such as when the solar cell is a back-contact cell, the grid electrodes 12 are all located on the second surface 102, while the first surface 101 does not have grid electrodes 12.

[0070] In some embodiments, the solar cell can be a gridless cell, in which case the grid line electrode 12 is a fine grid electrode. In other embodiments, the solar cell can also be a grid cell, in which case the grid line electrode 12 can include a main grid electrode and a fine grid electrode, which are electrically connected. The fine grid electrode is used to collect charge carriers, and the main grid electrode is used to collect the charge carriers collected by the fine grid electrode.

[0071] Continue to refer to Figure 1 and Figure 2 In some embodiments, the metal material of the gate electrode 12 includes at least one of gold, silver, copper, nickel, aluminum, and tin.

[0072] The battery body is subjected to a photo-annealing process in an atmosphere of passivating gas, which includes a halogen source gas. The halogen element in the halogen source gas diffuses into the substrate 10 during the photo-annealing process.

[0073] Photo-annealing can excite hydrogen elements in the functional layer 11, allowing them to diffuse into the substrate 10 and passivate defects in the substrate 10. By performing the photo-annealing process in a passivating gas atmosphere, halogen elements in the passivating gas diffuse into the substrate 10, further passivating defects on the surface and within the substrate 10, thus improving the performance of the solar cell. Furthermore, using halogen elements to passivate defects in the substrate 10 can also form more stable chemical bonds, which is beneficial for mitigating the static degradation problem of solar cells.

[0074] In some embodiments, the halogen element includes at least one of fluorine, chlorine, bromine, and iodine.

[0075] In some embodiments, the halogen element includes at least fluorine. When fluorine is used to passivate defects in the substrate 10, the resulting silicon-fluorine bonds are more stable. Therefore, including at least fluorine in the halogen element can further improve the static degradation problem of solar cells.

[0076] In some embodiments, the passivation gas further includes a hydrogen source gas, wherein hydrogen elements in the hydrogen source gas diffuse into the substrate 10 during the photo-annealing process. That is, a hydrogen source gas can also be provided during the photo-annealing process, and the hydrogen elements in the hydrogen source gas can also passivate defects in the substrate 10, thereby improving the performance of the solar cell.

[0077] In some embodiments, the ratio of the halogen source gas flow rate to the hydrogen source gas flow rate is 5 to 9, for example, 5, 6, 7, 8, or 9. Because halogens have high electronegativity, they can react with vacancy defects, uncoordinated ions, or dangling bonds in the substrate 10 to form more stable chemical bonds, resulting in a better passivation effect than hydrogen. Therefore, the ratio of the halogen source gas flow rate to the hydrogen source gas flow rate can be set within the above range to improve the passivation effect of the passivating gas.

[0078] In some embodiments, the flow rate of the halogen source gas is 1000 sccm to 5000 sccm, for example, 1000 sccm to 2500 sccm, 2500 sccm to 4000 sccm, or 4000 sccm to 5000 sccm. Exemplarily, the flow rate of the halogen source gas can be 1000 sccm, 1500 sccm, 2000 sccm, 2250 sccm, 2500 sccm, 3000 sccm, 3750 sccm, 4000 sccm, 4500 sccm, or 5000 sccm. A relatively large flow rate of the halogen source gas within the above range can provide sufficient halogen elements to the passivation substrate 10, thereby effectively improving the performance of the solar cell.

[0079] The flow rate of the hydrogen source gas is 500 sccm to 1000 sccm, for example, 500 sccm to 700 sccm, 700 sccm to 850 sccm, or 850 sccm to 1000 sccm. For example, the flow rate of the hydrogen source gas can be 500 sccm, 600 sccm, 700 sccm, 775 sccm, 850 sccm, 925 sccm, or 1000 sccm.

[0080] In some embodiments, the process temperature for photoannealing is 300°C to 1000°C, for example, 300°C to 500°C, 500°C to 800°C, or 800°C to 1000°C. For example, the process temperature can be 300°C, 400°C, 500°C, 650°C, 700°C, 800°C, 900°C, or 1000°C.

[0081] The light intensity for the light annealing process is 100mW / cm². 2 ~10000mW / cm 2 For example, 100mW / cm 2 ~1000mW / cm 2 1000mW / cm 2 ~3000mW / cm 2 3000mW / cm 2 ~5000mW / cm 2 5000mW / cm 2 ~8000mW / cm 2 Or 8000mW / cm 2 ~10000mW / cm 2 For example, the light intensity can be 100 mW / cm². 2 550mW / cm 2 1000mW / cm 2 2000mW / cm 2 3000mW / cm 2 4000mW / cm 2 5000mW / cm 2 6500mW / cm 2 8000mW / cm 2 9000mW / cm 2 Or 10000mW / cm 2 .

[0082] The pressure for the photoannealing process is 100 mbar to 3000 mbar, for example, 100 mbar to 700 mbar, 700 mbar to 1500 mbar, or 1500 mbar to 3000 mbar. For example, the pressure can be 100 mbar, 400 mbar, 700 mbar, 1100 mbar, 1500 mbar, 2250 mbar, or 3000 mbar.

[0083] The process time for light annealing is 20 min to 35 min, for example, 20 min to 25 min, 25 min to 30 min, or 30 min to 35 min. For example, the process time is 20 min, 22.5 min, 25 min, 27.5 min, 30 min, 32.5 min, or 35 min.

[0084] The passivation gas flow rate is 1000 sccm to 6000 sccm. For example, 1000 sccm to 2500 sccm, 2500 sccm to 4000 sccm, or 4000 sccm to 6000 sccm. For instance, the passivation gas flow rate can be 1000 sccm, 1500 sccm, 2000 sccm, 2250 sccm, 2500 sccm, 3000 sccm, 3750 sccm, 4000 sccm, 4500 sccm, 5000 sccm, or 6000 sccm.

[0085] The above process parameters refer to those for photo-annealing without an electric field. The passivation gas flow rate is the total gas flow rate; for example, when the passivation gas includes both hydrogen and halogen source gases, the passivation gas flow rate is the sum of the hydrogen and halogen source gas flow rates. The photo-annealing process duration is the total duration of the heating, photo-irradiation, and cooling steps.

[0086] In addition, when no electric field is provided, the duration of the photo-irradiation step in the photo-annealing process can be 5s to 50s, for example, 5s to 19s, 19s to 35s, or 35s to 50s. For example, the duration of the photo-irradiation step is 5s, 10s, 12s, 20s, 27s, 35s, 42.5s, or 50s.

[0087] In some embodiments, the photoannealing process includes: a heating step, which raises the temperature of the battery body to a target temperature; and a photoirradiation step, which provides light energy to the heated battery body. In the photoirradiation step, at least a passivating gas is provided. The heating step can provide energy for the migration of hydrogen elements in the functional layer 11. The photoirradiation step can regulate the valence state of hydrogen elements, enabling them to bond with dangling bonds in the substrate 10, thereby passivating defects in the substrate 10. The passivating gas provided in the photoirradiation step allows halogen elements in the passivating gas to migrate into the surface of the substrate 10 under the influence of heat and light energy, thus passivating defects in the substrate 10.

[0088] In some embodiments, the photoannealing process further includes a cooling step to reduce the temperature of the battery body after the photo-irradiation step to a preset temperature. This cooling step allows the internal structure of the battery body to gradually stabilize, facilitating the normal removal of the solar cell from the process chamber.

[0089] In some embodiments, the method for fabricating a solar cell further includes providing an electric field to convert a passivation gas into plasma. The cell can convert the passivation gas into plasma, facilitating the diffusion of halogen elements from the passivation gas into the substrate 10, thereby passivating defects in the substrate 10.

[0090] In some embodiments, the electric field strength is 50V / cm to 500V / cm, for example, 50V / cm to 150V / cm, 150V / cm to 300V / cm, or 300V / cm to 500V / cm. Exemplarily, the electric field strength can be 50V / cm, 100V / cm, 150V / cm, 200V / cm, 225V / cm, 300V / cm, 400V / cm, or 500V / cm.

[0091] The discharge frequency of the electric field is 10mHz to 60mHz, for example, 10mHz to 25mHz, 25mHz to 40mHz, or 40mHz to 60mHz. For example, the discharge frequency of the electric field can be 10mHz, 17.5mHz, 25mHz, 32.5mHz, 40mHz, 50mHz, or 60mHz.

[0092] The power density of the electric field is 0.1 W / cm². 2 ~1W / cm 2 For example, 0.1 W / cm 2 ~0.3W / cm 2 0.3W / cm 2 ~0.6W / cm 2 0.6W / cm 2 ~1W / cm 2 For example, the power density of the electric field can be 0.1 W / cm². 2 0.2W / cm 2 0.3W / cm 2 0.45W / cm 2 0.6W / cm 2 0.8W / cm 2 Or 1W / cm 2 When the relevant parameters of the electric field are within the above range, the passivation gas can be effectively converted into plasma, which helps the halogen element diffuse into the substrate 10 so that the halogen element passivates the substrate 10.

[0093] Introducing an electric field into the photo-annealing process can effectively shorten the process time and improve the fabrication efficiency of solar cells. Furthermore, since the electric field helps passivation gas transform into plasma, compared to methods without an electric field, photo-annealing with an electric field can lower the process temperature, and the passivation gas can also gain sufficient energy through the electric field to diffuse to the substrate. Therefore, introducing an electric field into the photo-annealing process can improve the fabrication efficiency of solar cells and reduce their fabrication costs.

[0094] In some embodiments, after providing an electric field in the photoannealing process step, the process temperature of the photoannealing process is 200°C to 600°C, for example, 200°C to 300°C, 300°C to 400°C, or 400°C to 600°C. The temperature of the photoannealing process can be 200°C, 250°C, 300°C, 350°C, 400°C, 500°C, or 600°C.

[0095] After providing an electric field during the photo-annealing process, the light intensity for the photo-annealing process is 100 mW / cm². 2 ~10000mW / cm 2 For example, 100mW / cm 2 ~1000mW / cm 2 1000mW / cm 2 ~3000mW / cm 2 3000mW / cm 2 ~5000mW / cm 2 5000mW / cm 2 ~8000mW / cm 2 Or 8000mW / cm 2 ~10000mW / cm 2 For example, the light intensity can be 100 mW / cm². 2 550mW / cm 2 1000mW / cm 2 2000mW / cm 2 3000mW / cm 2 4000mW / cm 2 5000mW / cm 2 6500mW / cm 2 8000mW / cm 2 9000mW / cm 2 Or 10000mW / cm 2 .

[0096] After providing an electric field in the photo-annealing process, the pressure of the photo-annealing process is 100 mbar to 3000 mbar, for example, 100 mbar to 700 mbar, 700 mbar to 1500 mbar, or 1500 mbar to 3000 mbar. For example, the pressure can be 100 mbar, 400 mbar, 700 mbar, 1100 mbar, 1500 mbar, 2250 mbar, or 3000 mbar.

[0097] After providing an electric field in the photo-annealing process, the process duration of the photo-annealing process is 10 min to 25 min, for example, 10 min to 15 min, 15 min to 20 min, or 20 min to 25 min. Examples include process durations of 10 min, 12.5 min, 15 min, 17.5 min, 20 min, 22.5 min, or 25 min.

[0098] After providing an electric field in the photo-annealing process, the passivation gas flow rate is 1000 sccm to 6000 sccm. For example, 1000 sccm to 2500 sccm, 2500 sccm to 4000 sccm, or 4000 sccm to 6000 sccm. Exemplarily, the passivation gas flow rate can be 1000 sccm, 1500 sccm, 2000 sccm, 2250 sccm, 2500 sccm, 3000 sccm, 3750 sccm, 4000 sccm, 4500 sccm, 5000 sccm, or 6000 sccm.

[0099] After providing an electric field in the photo-annealing process, the duration of the illumination step in the photo-annealing process can be from 1 s to 30 s, for example, 1 s to 10 s, 10 s to 20 s, or 20 s to 30 s. For example, the illumination step duration can be 1 s, 5.5 s, 10 s, 15.5 s, 20 s, 25.5 s, or 30 s. Compared to a solution without an electric field, the photo-annealing process with an electric field can reduce the illumination duration, and the passivation gas can also obtain sufficient energy through the electric field to diffuse to the substrate 10. Therefore, introducing an electric field in the photo-annealing process can improve the fabrication efficiency of solar cells and save on the fabrication cost of solar cells.

[0100] The comparative example is a battery body processed at a temperature of 200℃ and a light intensity of 1000mW / cm². 2 The battery was obtained after a photo-annealing process at atmospheric pressure (1013.25 mbar) for 25 minutes. In the example, the battery body underwent a process at 200°C and a light intensity of 1000 mW / cm². 2The solar cell was obtained after a photo-annealing process at atmospheric pressure (1013.25 mbar), a halogen source gas flow rate of 2500 sccm, and a process duration of 25 minutes. Experimental tests showed that the fill factor of the solar cell in this embodiment was at least 0.6% higher than that of the solar cell in the comparative example, and the open-circuit voltage of the solar cell in this embodiment was at least 0.3% higher than that of the solar cell in the comparative example. That is, photo-annealing in a passivating gas atmosphere can effectively improve the performance of the solar cell. A 30-day static degradation experiment was conducted on the solar cells in the comparative example and the solar cell in this embodiment. The results showed that the fill factor of the solar cell in the comparative example decreased by at least 0.5% after 30 days of static storage, while the fill factor of the solar cell in this embodiment remained essentially unchanged after 30 days of static storage. Therefore, photo-annealing in a passivating gas atmosphere can effectively improve the static degradation problem of solar cells in this embodiment.

[0101] Accordingly, another aspect of this application embodiment also provides a solar cell, which can be prepared by the solar cell preparation method in any of 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 in the foregoing embodiments, and will not be repeated hereafter.

[0102] refer to Figure 2 or Figure 3 The solar cell includes a substrate 10, a functional layer 11, grid electrodes 12, and halogen elements. The functional layer 11 is located on the substrate 10; at least a portion of the grid electrodes 12 is located on the functional layer 11; and the halogen elements are located within the surface of the substrate 10. That is, the surface and interior of the substrate 10 contain halogen elements, which can passivate defects in the substrate 10 and improve the performance of the solar cell. Furthermore, the halogen elements can form more stable chemical bonds with dangling bonds in the substrate 10, which is beneficial for improving the static degradation problem of the solar cell.

[0103] In some embodiments, the halogen element includes at least one of fluorine, chlorine, bromine, and iodine.

[0104] In some embodiments, the concentration of halogen is 1E3atom / cm³. 3 ~1E5atom / cm 3 For example, 1E3atom / cm 3 ~8E3atom / cm 3 8E3atom / cm 3 ~4E4atom / cm 3 Or 4E4atom / cm 3 ~1E5atom / cm 3For example, the concentration of halogens is 1E3atom / cm³. 3 4.5E3atom / cm 3 8E3atom / cm 3 1E4atom / cm 3 2.4E4atom / cm 3 4E4atom / cm 3 7E4atom / cm 3 Or 1E5atom / cm 3 .

[0105] In some embodiments, the solar cell also includes hydrogen elements located within the surface of the substrate 10. The hydrogen elements can also passivate defects in the substrate 10 and improve the performance of the solar cell.

[0106] Accordingly, another aspect of this application provides a tandem cell including the solar cells described in any of 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 hereafter.

[0107] Figure 4 This is a schematic diagram of a stacked battery provided in an embodiment of this application.

[0108] refer to Figure 4 The tandem solar cell includes a base cell 20 and a perovskite cell 21. The base cell 20 is a solar cell in any of the foregoing embodiments. The perovskite cell 21 is located on one side of the base cell 20.

[0109] In some embodiments, the perovskite solar cell 21 may include: a first transport layer, a perovskite substrate, a second transport layer, a transparent conductive layer, and an antireflection layer stacked together. The first transport layer is directly opposite the bottom cell 20.

[0110] In some examples, the first transport layer can be one of an electron transport layer and a hole transport layer, and the second transport layer can be the other of an electron transport layer and a hole transport layer.

[0111] In some embodiments, the bandgap width of the perovskite cell 21 is wider than that of the bottom cell 20. Therefore, stacking the perovskite cell 21 on top of the 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.

[0112] In some embodiments, the stacked cell may further include an intermediate connecting layer (not shown) connected between the bottom cell 20 and the perovskite cell 21.

[0113] In some embodiments, the intermediate connecting layer is generally a tunnel junction or a very thin metal or transparent electrode composite layer. Optionally, the intermediate connecting layer can be a transparent conductive oxide, which has good optoelectronic properties, high photon transmittance and high conductivity, thereby enabling the perovskite cell 21 and the bottom cell 20 to maintain good ohmic contact.

[0114] Accordingly, another aspect of this application provides a photovoltaic module, which includes the solar cell or the tandem cell described in any of 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 in the foregoing embodiments, and will not be repeated hereafter.

[0115] Figure 5 This is a schematic diagram of a photovoltaic module provided in an embodiment of this application.

[0116] refer to Figure 5 The photovoltaic module includes a cell string, which is formed by connecting multiple solar cells 30 prepared by any of the aforementioned methods, or by connecting multiple solar cells 30 prepared by any of the aforementioned methods, or by connecting multiple tandem cells prepared by any of the aforementioned methods. The photovoltaic module also includes an encapsulating film 31 and a cover plate 32, wherein the encapsulating film 31 is used to cover the surface of the cell string; and the cover plate 32 is used to cover the surface of the encapsulating film 31 facing away from the cell string.

[0117] In some embodiments, the solar cell 30 is electrically connected in the form of a whole cell or a sliced ​​cell to form multiple cell strings, and the multiple cell strings are electrically connected in series and / or parallel. The solar cell 30 can be a whole cell or a sliced ​​cell, and a sliced ​​cell refers to a cell formed by cutting a complete whole cell.

[0118] Multiple solar cells 30 can be electrically connected through solder strips 33.

[0119] In some embodiments, the encapsulating film 31 includes a first encapsulating layer and a second encapsulating layer. The first encapsulating layer covers one of the front and back sides of the solar cell 30, and the second encapsulating layer covers the other of the front and back sides of the solar cell 30. Specifically, at least one of the first and second encapsulating layers 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 and second encapsulating layers can also be an EP film, an EPE film, or a PVP film. Here, 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. 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.

[0120] In some cases, the first encapsulation layer and the second encapsulation layer still have a boundary line before lamination. After lamination, the photovoltaic module will no longer have the concept of a first encapsulation layer and a second encapsulation layer. That is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film 31.

[0121] 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 encapsulating film 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 includes a first cover plate and a second cover plate, the first cover plate being opposite to the first encapsulation layer, and the second cover plate being opposite to the second encapsulation layer.

[0122] 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 body is provided, the battery body including a substrate, a functional layer and grid line electrodes, the functional layer being located on the substrate, and at least a portion of the grid line electrodes being located on the functional layer; The battery body undergoes a photo-annealing process in an atmosphere of passivating gas, which includes a halogen source gas. During the photo-annealing process, the halogen element in the halogen source gas diffuses into the substrate. The passivating gas also includes a hydrogen source gas, and the hydrogen element in the hydrogen source gas diffuses into the substrate during the photo-annealing process. The ratio of the flow rate of the halogen source gas to the flow rate of the hydrogen source gas is 5 to 9.

2. The method for preparing a solar cell according to claim 1, characterized in that, The halogen element includes at least one of fluorine, chlorine, bromine, and iodine.

3. The method for preparing a solar cell according to claim 2, characterized in that, The halogen element includes at least fluorine.

4. The method for preparing a solar cell according to claim 1, characterized in that, The flow rate of the halogen source gas is 1000 sccm to 5000 sccm; the flow rate of the hydrogen source gas is 500 sccm to 1000 sccm.

5. The method for preparing a solar cell according to claim 1, characterized in that, The process temperature for the optical annealing process is 300℃~1000℃; the light intensity for the optical annealing process is 100mW / cm². 2 ~10000mW / cm 2 The pressure of the optical annealing process is 100 mbar to 3000 mbar; the process time of the optical annealing process is 20 min to 35 min; and the flow rate of the passivation gas is 1000 sccm to 6000 sccm.

6. The method for preparing a solar cell according to claim 1, characterized in that, The optical annealing process includes: The heating step raises the temperature of the battery body to a target temperature. The illumination step provides light energy to the heated battery body, wherein at least the passivating gas is provided in the illumination step.

7. A solar cell, characterized in that, The solar cell is prepared by the method for preparing a solar cell according to any one of claims 1 to 6, and the solar cell comprises: Base; A functional layer is located on the substrate; Gate line electrodes, at least a portion of which are located on the functional layer; A halogen element, wherein the halogen element is located within the surface of the substrate.

8. The solar cell according to claim 7, characterized in that, The halogen element includes at least one of fluorine, chlorine, bromine, and iodine.

9. The solar cell according to claim 7, characterized in that, The concentration of the halogen element is 1E3atom / cm³. 3 ~1E5atom / cm 3 .

10. A stacked battery, characterized in that, include: The bottom cell is a solar cell prepared by the method of preparing a solar cell as described in any one of claims 1 to 6, or a solar cell as described in any one of claims 7 to 9; A perovskite solar cell, wherein the perovskite solar cell is located on one side of the bottom solar cell.

11. 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 6, or by connecting multiple solar cells prepared by any one of claims 7 to 9, or by connecting multiple stacked cells as described in claim 10. 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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