Back contact solar cell and method of manufacturing the same, stacked cell, and photovoltaic module

Abstract

The embodiment of the present application relates to the photovoltaic field, and provides a back contact solar cell, a preparation method thereof, a laminated cell and a photovoltaic module. The back contact solar cell comprises: a substrate comprising opposite front and back surfaces, the back surface comprising a first region and a second region; a tunneling oxide layer, a first doped polysilicon layer and a first passivation structure which are stacked on the first region, the first passivation structure comprising a first porous layer, the first porous layer having a plurality of pores; a hydrogenated silicon oxide structure, a doped conductive layer and a transparent conductive layer which are stacked on the second region, the doped conductive layer being different from the first doped polysilicon layer in doping type; a first electrode located on a side of the first passivation structure away from the first doped polysilicon layer and electrically connected with the first doped polysilicon layer; and a second electrode located on a side of the transparent conductive layer away from the doped conductive layer and electrically connected with the doped conductive layer. The solar cell provided by the embodiment of the present application can at least improve the photoelectric conversion efficiency of the solar cell.

Description

Technical Field

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

[0002] In the field of solar cell technology, especially in the development of back contact (BC) solar cells, traditional process methods face some technical limitations that restrict further improvement in cell conversion efficiency. Summary of the Invention

[0003] This application provides a back-contact solar cell and its preparation method, a tandem cell, and a photovoltaic module, which at least helps to improve the cell conversion efficiency of the back-contact solar cell.

[0004] According to some embodiments of this application, one aspect of this application provides a back-contact solar cell, comprising: a substrate including a front side and a back side opposite to each other, the back side including a first region and a second region; a tunneling oxide layer, a first doped polycrystalline silicon layer and a first passivation structure stacked on the first region, the first passivation structure including a first porous layer having a plurality of pores; a hydrogenated silicon oxide structure, a doped conductive layer and a transparent conductive layer stacked on the second region, the doped conductive layer having a different doping type than the first doped polycrystalline silicon layer; a first electrode located on the side of the first passivation structure away from the first doped polycrystalline silicon layer and electrically connected to the first doped polycrystalline silicon layer; and a second electrode located on the side of the transparent conductive layer away from the doped conductive layer and electrically connected to the doped conductive layer.

[0005] In some embodiments, the first passivation structure further includes: a first silicon oxide layer located between the first doped polysilicon layer and the first porous layer; a second doped polysilicon layer located between the first silicon oxide layer and the first porous layer, wherein the second doped polysilicon layer and the first doped polysilicon layer have the same doping type; a first aluminum oxide layer located between the second doped polysilicon layer and the first porous layer; and a first silicon nitride layer located between the first aluminum oxide layer and the first porous layer.

[0006] In some embodiments, the substrate and the first doped polysilicon layer have the same doping type, and the doping concentration of the substrate, the doping concentration of the first doped polysilicon layer, and the doping concentration of the second doped polysilicon layer increase sequentially.

[0007] In some embodiments, the first passivation structure further includes: a second alumina layer located between the first doped polysilicon layer and the first porous layer; and a second silicon nitride layer located between the second alumina layer and the first porous layer.

[0008] In some embodiments, a portion of the first electrode is located within a portion of the hole.

[0009] In some embodiments, the hydrogenated silicon oxide structure includes a plurality of hydrogenated silicon oxide layers stacked between the second region and the doped conductive layer, wherein the oxygen content in the plurality of hydrogenated silicon oxide layers first increases and then decreases along the direction away from the second region.

[0010] In some embodiments, among the plurality of hydrogenated silicon oxide layers, the hydrogenated silicon oxide layer in contact with the second region is an intrinsic hydrogenated silicon oxide layer.

[0011] In some embodiments, the back surface further includes an insulating region located between the first region and the second region, and the back contact solar cell further includes: a third alumina layer located in the insulating region; and a hydrogenated silicon nitride layer located on the side of the third alumina layer away from the insulating region.

[0012] In some embodiments, the first region is a polished surface, and the second region, the insulating region, and the front surface have a textured surface.

[0013] In some embodiments, the back-contact solar cell further includes a second passivation structure located on the front side, the second passivation structure including a second porous layer having a plurality of pores.

[0014] According to some embodiments of this application, another aspect of this application provides a method for fabricating a back-contact solar cell, comprising: providing a substrate including a front side and a back side opposite to each other, the back side including a first region and a second region; sequentially stacking a tunneling oxide layer, a first doped polycrystalline silicon layer and a first passivation structure in the first region, the first passivation structure including a first porous layer having a plurality of pores; sequentially stacking a hydrogenated silicon oxide structure, a doped conductive layer and a transparent conductive layer in the second region, the doped conductive layer having a different doping type than the first doped polycrystalline silicon layer; forming a first electrode on the side of the first passivation structure away from the first doped polycrystalline silicon layer, such that the first electrode is electrically connected to the first doped polycrystalline silicon layer; and forming a second electrode on the side of the transparent conductive layer away from the doped conductive layer, such that the second electrode is electrically connected to the doped conductive layer.

[0015] In some embodiments, a hydrogenated silicon oxide structure, a doped conductive layer, and a transparent conductive layer are sequentially stacked in the second region, including: sequentially stacking a plurality of hydrogenated silicon oxide layers and the doped conductive layer in the second region using a chemical vapor deposition process, wherein the plurality of hydrogenated silicon oxide layers constitute the hydrogenated silicon oxide structure, and the oxygen content in the plurality of hydrogenated silicon oxide layers exhibits a trend of first increasing and then decreasing along the direction away from the second region; and forming the transparent conductive layer on the surface of the doped conductive layer away from the hydrogenated silicon oxide layer using a physical vapor deposition process.

[0016] In some embodiments, the back side further includes an insulating region located between the first region and the second region. A tunneling oxide layer, a first doped polysilicon layer, and a first passivation structure are sequentially stacked in the first region, comprising: forming the tunneling oxide layer in the first region; forming a polysilicon thin film on the surface of the tunneling oxide layer away from the substrate using a low-pressure chemical vapor deposition process; sequentially performing a phosphorus diffusion process and an oxidation process on the polysilicon thin film to form a stacked first doped polysilicon layer and a phosphosilicate glass layer on the tunneling oxide layer, wherein the thickness of the phosphosilicate glass layer is 60-100 nm; texturing the first region, the insulating region, and the front side to form a textured structure, and pre-cleaning and alkaline washing the battery structure with the textured structure to remove the phosphosilicate glass layer; and forming the first passivation structure on the front side and the first doped polysilicon layer using an atomic layer deposition process.

[0017] According to some embodiments of this application, another aspect of this application provides a tandem battery, comprising: a back-contact solar cell, wherein the back-contact solar cell is any of the back-contact solar cells described above, or a back-contact solar cell prepared by any of the back-contact solar cell preparation methods described above; and a perovskite solar cell electrically connected to the back-contact solar cell.

[0018] According to some embodiments of this application, another aspect of this application provides a photovoltaic module, including: a battery string, which is formed by connecting multiple back-contact solar cells as described in any one of the methods, or back-contact solar cells prepared by any one of the methods described in any one of the methods described in the method ... of the method described in the method described in the method described in the method of the method described

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

[0020] In the back-contact solar cell of this application, different film structures are used in the first and second regions on the back side of the substrate to form a hybrid back-contact solar cell. The first region on the back side uses a tunneling oxide layer, a first doped polycrystalline silicon layer, and a first passivation structure as a buffer film layer, which ensures good passivation effect in the first region and avoids reflection loss caused by setting a transparent conductive layer in the first region. This is beneficial to improving the conversion efficiency of the back-contact solar cell. Moreover, the first passivation structure includes a first porous layer with multiple pores, which increases the effective optical path after light enters the cell from the front, thereby improving light utilization and improving the cell conversion efficiency. The second region on the back side uses a stack of hydrogenated silicon oxide structure, doped conductive layer, and transparent conductive layer, which achieves both efficient passivation and ensures good conductivity. Attached Figure Description

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

[0022] Figure 1 This is a schematic diagram of the structure of a first type of back-contact solar cell provided in one embodiment of this application;

[0023] Figure 2 This is a schematic diagram of the structure of a second type of back-contact solar cell provided in one embodiment of this application;

[0024] Figure 3 This is a schematic diagram of the structure of a third type of back-contact solar cell provided in one embodiment of this application;

[0025] Figure 4 This is a schematic flowchart of a method for fabricating a back-contact solar cell according to an embodiment of this application;

[0026] Figure 5 This is a schematic diagram of a stacked battery provided in one embodiment of this application;

[0027] Figure 6 This is a schematic diagram of another stacked battery structure provided in one embodiment of this application;

[0028] Figure 7 This is a schematic diagram of another stacked battery provided in one embodiment of the present application;

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

[0030] The accompanying drawings include the following reference numerals:

[0031] 10. Substrate; 11. Tunneling oxide layer; 12. First doped polycrystalline silicon layer; 13. First passivation structure; 14. First porous layer; 15. Hydrogenated silicon oxide structure; 151. First hydrogenated silicon oxide layer; 152. Second hydrogenated silicon oxide layer; 153. Third hydrogenated silicon oxide layer; 16. Doped conductive layer; 17. Transparent conductive layer; 18. First electrode; 19. Second electrode; 20. First silicon oxide layer; 21. Second doped polycrystalline silicon layer 21. Silicon layer; 22. First alumina layer; 23. First silicon nitride layer; 24. Second alumina layer; 25. Second silicon nitride layer; 26. Third alumina layer; 27. Hydrogenated silicon nitride layer; 28. Second passivation structure; 29. ​​Second porous layer; 30. Fourth alumina layer; 31. Third silicon nitride layer; 100. Back contact solar cell; 200. Perovskite cell; 300. Cell string; 400. Encapsulating film; 500. Cover plate. Detailed Implementation

[0032] As is known from the background art, the conversion efficiency of existing back-contact solar cells needs further improvement. Based on this, this application provides a back-contact solar cell and its fabrication method, a tandem cell, and a photovoltaic module. The back-contact solar cell of this application includes: a substrate comprising a front side and a back side, the back side comprising a first region and a second region; a tunneling oxide layer, a first doped polycrystalline silicon layer, and a first passivation structure stacked in the first region, the first passivation structure comprising a first porous layer having multiple pores; a hydrogenated silicon oxide structure, a doped conductive layer, and a transparent conductive layer stacked in the second region, the doped conductive layer having a different doping type than the first doped polycrystalline silicon layer; a first electrode located on the side of the first passivation structure away from the first doped polycrystalline silicon layer and electrically connected to the first doped polycrystalline silicon layer; and a second electrode located on the side of the transparent conductive layer away from the doped conductive layer and electrically connected to the doped conductive layer.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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).

[0037] 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.

[0038] 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 terms in the embodiments of this application can be understood according to the specific circumstances.

[0039] In the accompanying drawings corresponding to the embodiments of this application, the thickness and area of ​​the layers are enlarged for better understanding and ease of description. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component may be "directly" located on the surface of the other component, or there may be a third component between the two components. Conversely, when describing a component on the surface of another component, or when another component is formed or disposed on the surface of a component, it indicates that there is no third component between the two components. Furthermore, when describing a component as being "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0040] 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.

[0041] 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 "part" is also intended to include the plural form unless the context clearly indicates otherwise. Components include layers, films, regions, or plates, etc.

[0042] 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.

[0043] One embodiment of this application provides a back-contact solar cell. Figure 1 A schematic diagram of the structure of a back-contact solar cell according to an embodiment of this application is shown as an example. Figure 2 A schematic diagram of the structure of a back-contact solar cell according to another embodiment of this application is shown as an example. Figure 1 and Figure 2 As shown, the back-contact solar cell of this application includes:

[0044] The substrate 10 includes a front side and a back side, the back side including a first region and a second region;

[0045] Specifically, the front side of the substrate 10 is the light-receiving surface of the back-contact solar cell, and the back side of the substrate 10 is the back-light-receiving surface of the back-contact solar cell. The substrate 10 can receive incident light and generate photogenerated carriers. The first region and the second region have different doping types. Optionally, the substrate 10 can be a silicon substrate, and the material of the silicon substrate can include monocrystalline silicon and polycrystalline silicon, etc. Optionally, the substrate 10 and the first region are both N-type doped, and the second region is P-type doped.

[0046] A tunneling oxide layer 11, a first doped polysilicon layer 12, and a first passivation structure 13 are stacked in the first region. The first passivation structure 13 includes a first porous layer 14, which has a plurality of pores.

[0047] Specifically, the tunneling oxide layer 11 serves as a tunnel between the first doped polysilicon layer 12 and the substrate 10, allowing charge carriers to pass through rapidly via the tunneling effect without affecting charge collection efficiency. The first passivation structure 13 includes a first porous layer 14 with multiple pores. The presence of these pores facilitates hydrogen permeation, passivates dangling bonds on the surface of the substrate 10, reduces surface recombination, and improves battery performance. Furthermore, the first porous layer 14 increases the battery's light absorption, improving photoelectric conversion efficiency. The first doped polysilicon layer 12 serves as a charge collection and transport medium. Optionally, the pores are nanoscale pores. The pores can be distributed in the surface region of the first porous layer 14 away from the first doped polysilicon layer 12.

[0048] The hydrogenated silicon oxide structure 15, the doped conductive layer 16, and the transparent conductive layer 17 are stacked in the second region. The doped conductive layer 16 has a different doping type than the first doped polysilicon layer 12.

[0049] Specifically, the hydrogenated silicon oxide structure 15 is a silicon oxide structure containing hydrogen atoms, which can provide additional passivation effects, reduce surface recombination, and improve the open-circuit voltage of the battery. The doped conductive layer 16 acts as a carrier for charge carriers, collecting them and transporting them to the electrodes. The transparent conductive layer 17 can provide a good conductive path while maintaining transparency, facilitating good contact between the electrodes and the battery interior, reducing resistance loss, and improving the overall performance and stability of the battery.

[0050] The first electrode 18 is located on the side of the first passivation structure 13 away from the first doped polysilicon layer 12, and is electrically connected to the first doped polysilicon layer 12.

[0051] The second electrode 19 is located on the side of the transparent conductive layer 17 away from the doped conductive layer 16, and is electrically connected to the doped conductive layer 16.

[0052] In the aforementioned embodiment, the back-contact solar cell employs different film structures in the first and second regions on the back side of the substrate, forming a hybrid back-contact solar cell. The first region on the back side uses a tunneling oxide layer, a first doped polycrystalline silicon layer, and a first passivation structure as a buffer layer, ensuring good passivation performance and avoiding reflection losses caused by the transparent conductive layer in the first region. This is beneficial for improving the conversion efficiency of the back-contact solar cell. Furthermore, the first passivation structure includes a porous layer with multiple pores, increasing the effective optical path after light enters the cell from the front, thereby improving light utilization and enhancing the cell's conversion efficiency. The second region on the back side uses a stacked structure of hydrogenated silicon oxide, a doped conductive layer, and a transparent conductive layer, achieving both efficient passivation and good conductivity.

[0053] In addition, the presence of the first porous layer 14 is beneficial to increasing the mechanical strength of the battery module, especially in processing steps such as laser processing and electrode fabrication, which can effectively prevent structural damage caused by stress concentration. This can further improve the photoelectric conversion efficiency of the battery and ensure the stability of the battery.

[0054] In one alternative, the thickness of the surface region in the first porous layer 14 can be 0.015 to 0.16 times the total thickness of the first porous layer 14.

[0055] Furthermore, the thickness of the first porous layer 14 can be 90~200 nm, and the thickness of the surface region can be 3~15 μm. In the surface region, the pores can be randomly distributed or uniformly distributed. The average density of the pores in the surface region can be 5000~50000 pores / cm³. 2 .

[0056] For example, the first region is an N-type doped region, that is, the first region is doped with N-type ions, which can be phosphorus, arsenic or antimony; the second region is a P-type doped region, that is, the second region is doped with P-type ions, which can be boron, aluminum or gallium.

[0057] In other embodiments, the first region may be a P-type doped region and the second region may be an N-type doped region.

[0058] Optionally, the substrate 10 can be an N-type semiconductor substrate, meaning that the substrate 10 is doped with N-type ions, specifically at least one of phosphorus, arsenic, or antimony. The substrate 10 can also be a P-type semiconductor substrate, meaning that the substrate 10 is doped with P-type ions, specifically boron, aluminum, or gallium.

[0059] In some embodiments, such as Figure 2 As shown, the first passivation structure 13 further includes: a first silicon oxide layer 20, located between the first doped polysilicon layer 12 and the first porous layer 14; a second doped polysilicon layer 21, located between the first silicon oxide layer 20 and the first porous layer 14, wherein the second doped polysilicon layer 21 and the first doped polysilicon layer 12 have the same doping type; a first aluminum oxide layer 22, located between the second doped polysilicon layer 21 and the first porous layer 14; and a first silicon nitride layer 23, located between the first aluminum oxide layer 22 and the first porous layer 14. That is, along the direction from the tunneling oxide layer 11 to the first doped polysilicon layer 12, the first silicon oxide layer 20, the second doped polysilicon layer 21, the first aluminum oxide layer 22, the first silicon nitride layer 23, and the first porous layer 14 are arranged sequentially. In this embodiment, the first silicon oxide layer 20 is adjacent to the first doped polycrystalline silicon layer 12, which not only enhances the passivation capability of the interface but also provides additional chemical stability. Subsequently, the second doped polycrystalline silicon layer 21 further strengthens the passivation effect, forming a composite structure together with the first doped polycrystalline silicon layer 12. This structure can better suppress carrier recombination and improve photoelectric conversion efficiency. Next, the first alumina layer 22 and the first silicon nitride layer 23 are stacked sequentially, which play an excellent field-effect passivation role. The presence of the first alumina layer 22 can also increase the effective optical path length of light after it enters the battery from the textured surface, improving light utilization. In addition, the design of the first porous layer 14 effectively increases the effective path length of light, promoting light absorption and conversion. This series of layered structures works synergistically to buffer the electrode and passivation layer, reducing reflection loss in the first region.

[0060] Furthermore, the substrate 10 and the first doped polysilicon layer 12 have the same doping type, and the doping concentration of the substrate 10, the first doped polysilicon layer 12, and the second doped polysilicon layer 21 increases sequentially. In this embodiment, the substrate 10 and the first doped polysilicon layer 12 have the same doping type, forming a homojunction structure. The doping concentration of the substrate 10, the first doped polysilicon layer 12, and the second doped polysilicon layer 21 increases sequentially, constructing a doping system with a gradually changing concentration gradient. This structural design allows the carriers to experience a gradual change in environment from low concentration to high concentration during transport from the substrate 10 to the first doped polysilicon layer 12 and then to the second doped polysilicon layer 21. This is beneficial for the efficient transport and collection of carriers, while reducing recombination losses caused by the rapid migration of carriers between different doping concentration regions. As the doping concentration gradually increases, the conversion efficiency and stability of the battery can be significantly improved. In addition, setting a concentration gradient can enhance the battery's ability to absorb light, especially long-wavelength light, which can further improve the overall performance of the battery.

[0061] For example, the doping concentration of the substrate 10 is 5e14~1e15cm. -3 The doping concentration of the first doped polysilicon layer 12 is 3e19~5e20cm. -3 The doping concentration of the second doped polysilicon layer 21 is 1e20~8e20cm. -3 .

[0062] In another exemplary embodiment, the doping concentration of the first doped polysilicon layer 12 and the doping concentration of the second doped polysilicon layer 21 are the same and greater than the doping concentration of the substrate 10.

[0063] Furthermore, the doping concentration of the substrate 10 is 5e14~1e15cm. -3 The doping concentration of the first doped polysilicon layer 12 and the second doped polysilicon layer 21 is 3e19~8e20cm. -3 .

[0064] In other embodiments of this application, such as Figure 1As shown, the first passivation structure 13 further includes: a second alumina layer 24, located between the first doped polycrystalline silicon layer 12 and the first porous layer 14; and a second silicon nitride layer 25, located between the second alumina layer 24 and the first porous layer 14. In this embodiment, the first doped polycrystalline silicon layer 12, the second alumina layer 24, the second silicon nitride layer 25, and the first porous layer 14 are arranged sequentially. The combination of the second alumina layer 24 and the second silicon nitride layer 25 provides additional passivation effect and adjusts the optical properties of the surface, reducing light reflection and promoting more efficient light absorption. Furthermore, the presence of the second alumina layer 24 can increase the effective optical path of light entering the battery from the textured surface, thereby improving light utilization.

[0065] For example, the thickness of the first alumina layer 22 can be 1~4 nm. The thickness of the second alumina layer 24 can be 1~4 nm.

[0066] According to some alternative embodiments of this application, a portion of the first electrode is located within a portion of the cavity. This embodiment, by extending a portion of the first electrode into the cavity of the battery structure, increases the contact area between the electrode and the battery substrate, thereby reducing contact resistance and improving current collection efficiency. Simultaneously, the electrode portion within the cavity can form a more robust mechanical connection with the battery substrate, effectively preventing the electrode from detaching due to external forces during use, thus enhancing battery reliability. Furthermore, this design helps improve the uniformity of electrode material distribution, ensuring consistent performance across different parts of the battery, thereby improving overall battery performance and production yield.

[0067] In some embodiments, the hydrogenated silicon oxide structure 15 includes a plurality of hydrogenated silicon oxide layers (not shown) stacked between the second region of the substrate 10 and the doped conductive layer 16. The oxygen content in the plurality of hydrogenated silicon oxide layers exhibits a trend of first increasing and then decreasing along the direction away from the second region. That is, along the direction from the second region of the substrate 10 to the transparent conductive layer 17, the oxygen content in the plurality of hydrogenated silicon oxide layers exhibits a trend of first increasing and then decreasing. In this embodiment, a stepped wide-bandgap hydrogenated silicon oxide layer stack structure is used instead of a narrow-bandgap hydrogenated intrinsic amorphous silicon layer. By adjusting the oxygen content, the film bandgap is controlled, which can effectively suppress epitaxial growth that is harmful to the crystalline silicon substrate and enhance the passivation effect. The oxygen content exhibiting a trend of first increasing and then decreasing can make the hydrogenated silicon oxide layer and the substrate 10 or the doped conductive layer 16 on both sides form a bandgap buffer, increasing the probability of carrier collection.

[0068] For example, X-ray photoelectron spectroscopy (XPS) can be used to test the oxygen content in a hydrogenated silicon oxide layer. The specific testing process is as follows: prepare a sample and fix it on a sample stage inside the XPS test chamber; control the XPS test chamber to be a vacuum environment; irradiate the sample surface with an X-ray source (such as an Al Kα or Mg Kα X-ray source) to excite electrons on the sample surface; use an energy analyzer to detect the excited photoelectrons and record their energy distribution; collect photoelectron spectra in the Si 2p and O 1s regions. The spectrum in the Si 2p region is used to determine the chemical state of silicon, and the spectrum in the O 1s region is used to analyze the oxygen content and chemical environment; subtract the background signal from the photoelectron spectrum to obtain pure Si 2p and O 1s photoelectron spectra; perform peak fitting on the spectrum in the O 1s region to decompose the total oxygen peak into the contributions of oxygen in different chemical states (such as Si-O, Si-OH, O2, etc.); based on the peak intensity and area, combined with a reference standard, the oxygen content in the sample can be estimated.

[0069] The oxygen concentration gradient change in the hydrogenated silicon oxide layer in this application can also mitigate the negative impact of high-temperature processes on battery performance. This is because the hydrogenated silicon oxide layer with lower oxygen content, located far from the second region, can better adapt to subsequent processing, reducing process difficulty and cost, while ensuring good battery performance and reliability.

[0070] Specifically, the oxygen content in the hydrogenated silicon oxide layer refers to the average oxygen content in the hydrogenated silicon oxide layer.

[0071] In one exemplary solution, such as Figure 3 As shown, the hydrogenated silicon oxide structure 15 includes three hydrogenated silicon oxide layers, namely a first hydrogenated silicon oxide layer 151, a second hydrogenated silicon oxide layer 152, and a third hydrogenated silicon oxide layer 153, which are stacked sequentially in a direction away from the second region. The oxygen content in the first hydrogenated silicon oxide layer 151 is 9%~12%, the oxygen content in the second hydrogenated silicon oxide layer 152 is 30%~35%, and the oxygen content in the third hydrogenated silicon oxide layer 153 is 6%~8%.

[0072] To further ensure the passivation effect of the silicon dioxide structure, according to some embodiments of this application, among the plurality of silicon dioxide layers, the silicon dioxide layer in contact with the second region is an intrinsic silicon dioxide layer. In this embodiment, since the silicon dioxide structure is a stacked structure, the silicon dioxide layer closest to the second region is not affected by the diffusion of dopant ions in the doped conductive layer, thereby ensuring that this layer is an intrinsic silicon dioxide layer.

[0073] According to one embodiment of this application, the oxygen doping ratio of the first hydrogenated silicon oxide layer is 1~2%, and the oxygen doping ratio of the second hydrogenated silicon oxide layer is 5~15%.

[0074] Furthermore, each of the hydrogenated silicon oxide layers described in this application is an intrinsic hydrogenated silicon oxide layer.

[0075] In the actual manufacturing process, due to the presence of dopant in the doped conductive layer, dopant diffusion occurs between the doped conductive layer and part of the hydrogenated silicon oxide layer, resulting in a small amount of dopant appearing in the intrinsic hydrogenated silicon oxide layer, which should be intrinsic. Even with slight doping, the hydrogenated silicon oxide layer can still provide a certain degree of surface passivation.

[0076] To prevent excessive diffusion of dopants from the doped conductive layer into the hydrogenated silicon oxide layer, precise temperature and time control is required during fabrication. For example, dopant diffusion can be limited through the following methods: lowering the temperature: the diffusion rate increases with temperature, so the temperature should be kept as low as possible during the formation of the hydrogenated silicon oxide layer to reduce diffusion; shortening the time: reducing the time spent on high-temperature processing during fabrication also helps limit the degree of diffusion; adding a barrier layer: adding an extremely thin barrier layer (such as silicon oxide or silicon nitride) between the doped conductive layer and the hydrogenated silicon oxide layer can act as a physical barrier to prevent or reduce dopant diffusion.

[0077] In some embodiments, the structure of the back contact solar cell is as follows: Figure 1 In the case of the structure shown, the thickness of the tunneling oxide layer 11 can be 1~3nm, the thickness of the first doped polysilicon layer 12 can be 90~200nm, the thickness of the second aluminum oxide layer 24 can be 3~12nm, and the thickness of the second silicon nitride layer 25 can be 75~115nm.

[0078] In some embodiments, the structure of the back contact solar cell is as follows: Figure 2 In the structure shown, the thickness of the tunneling oxide layer 11 can be 1~3 nm, the thickness of the first doped polysilicon layer 12 can be 30~60 nm, the thickness of the first silicon oxide layer 20 can be 1~3 nm, the thickness of the second doped polysilicon layer 21 can be 60~12 nm, the thickness of the first aluminum oxide layer 22 can be 3~12 nm, and the thickness of the first silicon nitride layer 23 can be 75~115 nm.

[0079] In other embodiments, such as Figure 1 and Figure 2As shown, the back side also includes an insulating region located between the first and second regions. The back contact solar cell further includes: a third alumina layer 26 located in the insulating region; and a silicon nitride (HNDI) layer 27 located on the side of the third alumina layer 26 away from the insulating region. Stacking the third alumina layer 26 and the HNDI layer 27 in the back insulating region achieves a dual improvement in the electrical and mechanical properties of the back contact solar cell. The third alumina layer 26, as an excellent insulating and passivating material, effectively isolates direct contact between different charge regions, thereby reducing the risk of leakage. The HNDI layer 27 plays a dual role: on the one hand, it provides additional passivation, further optimizing the recombination path of charge carriers; on the other hand, this layer also acts as a protective layer on the cell surface, enhancing its resistance to environmental factors.

[0080] Optionally, the first region is a polished surface, and the second region, the insulating region, and the front surface have a textured structure. The polished surface helps to form a smoother and more uniform tunneling oxide layer 11 and doped polycrystalline silicon layer; the textured structure increases the effective path length of light inside the cell through its rough surface and can also reduce light reflection on the cell surface, thereby improving the cell's light absorption rate, which helps to increase the cell's short-circuit current density.

[0081] Specifically, in the second region, the insulating region, and the front surface textured structure, the base size of the textured surface can be 7~30μm.

[0082] In some embodiments, such as Figure 1 and Figure 2 As shown, the back-contact solar cell further includes a second passivation structure 28, located on the front side. The second passivation structure includes a second porous layer 29, which has multiple pores. In this embodiment, the porous structure of the second porous layer 29 effectively passivates the dangling bonds of the substrate 10, reduces the surface recombination rate, increases the open-circuit voltage, and also increases the light travel path on the front side of the cell. This makes the reflection and scattering patterns of light on the cell surface more complex, increasing the effective optical path length of light inside the cell, thereby improving the light absorption rate.

[0083] In one specific embodiment, such as Figure 1 and Figure 2 As shown, the second passivation structure 28 further includes: a fourth aluminum oxide layer 30, located between the front side of the substrate 10 and the second porous layer 29; and a third silicon nitride layer 31, located between the fourth aluminum oxide layer 30 and the second porous layer 29.

[0084] Optionally, the pores of the second porous layer 29 are nanoscale pores. The pores of the second porous layer 29 may be distributed in the surface region of the second porous layer 29 away from the substrate 10.

[0085] Optionally, the thickness of the surface region in the second porous layer 29 can be 0.15 to 0.75 of the total thickness of the second porous layer 29.

[0086] Furthermore, the thickness of the second porous layer 29 can be 10-20 nm, and the thickness of the surface region can be 3-15 μm. In this surface region, the pores can be randomly or uniformly distributed. The average density of the pores in the second porous layer 29 in the surface region can be 5000-50000 pores / cm³. 2 .

[0087] Furthermore, the second passivation structure of this application may also include: a silicon oxynitride stack structure located on the side of the second porous layer away from the third silicon oxide layer; and a second silicon oxide layer located on the side of the silicon oxynitride stack structure away from the second porous layer.

[0088] Specifically, the silicon oxynitride stacked structure may include a first silicon oxynitride layer, a second silicon oxynitride layer, and a third silicon oxynitride layer stacked between the second porous layer and the second silicon oxide layer. In the second passivation structure, the thickness of the fourth aluminum oxide layer can be 3-12 nm, the thickness of the third silicon oxynitride layer can be 6-10 nm, the thickness of the second porous layer can be 10-20 nm, the thickness of the first silicon oxynitride layer can be 20-30 nm, the thickness of the second silicon oxynitride layer can be 10-15 nm, the thickness of the third silicon oxynitride layer can be 13-25 nm, and the thickness of the second silicon oxide layer can be 8-18 nm.

[0089] For example, such as Figure 1 and Figure 2 As shown, the first electrode 18 is in electrical contact with the first doped polycrystalline silicon layer 12. In this case, the interlocking structure of the first porous layer 14 and the first electrode 18 can significantly enhance the adhesion strength of the electrode and ensure the mechanical reliability of the battery.

[0090] Specifically, the tunneling oxide layer 11 can be made of a dielectric material, such as silicon oxide. The first doped polycrystalline silicon layer 12, the second doped polycrystalline silicon layer 21, and the doped conductive layer 16 can be single-layer structures or multilayer stacked structures. The doped conductive layer 16 can be made of doped amorphous silicon, doped microcrystalline silicon, or doped nanocrystalline silicon. The transparent conductive layer 17 can be made of TCO, AZO, or ITO. The first electrode 18 and the second electrode 19 can be made of silver or non-silver conductive materials; their materials can be the same or different. The first porous layer 14 and the second porous layer can each be a porous silicon nitride layer.

[0091] Another aspect of this application embodiment also provides a method for fabricating the aforementioned back-contact solar cell. Figure 4 A flowchart of a method for fabricating a back-contact solar cell is illustrated, as follows: Figure 4 As shown, the preparation method includes:

[0092] Step S201: Provide a substrate, the substrate including opposing front and back sides, the back side including a first region and a second region;

[0093] Step S202: A tunneling oxide layer, a first doped polysilicon layer, and a first passivation structure are sequentially stacked in the first region. The first passivation structure includes a first porous layer with multiple pores.

[0094] Step S203: A hydrogenated silicon oxide structure, a doped conductive layer, and a transparent conductive layer are sequentially stacked in the second region. The doped conductive layer has a different doping type than the first doped polysilicon layer.

[0095] Step S204: A first electrode is formed on the side of the first passivation structure away from the first doped polysilicon layer, so that the first electrode is electrically connected to the first doped polysilicon layer.

[0096] Step S205: A second electrode is formed on the side of the transparent conductive layer away from the doped conductive layer, such that the second electrode is electrically connected to the doped conductive layer.

[0097] In the above embodiment, a substrate including a first region and a second region on the back side is firstly provided; then a tunneling oxide layer, a first doped polysilicon layer, and a first passivation structure including a first porous layer are sequentially stacked on the first region on the back side; then, a hydrogenated silicon oxide structure, a doped conductive layer, and a transparent conductive layer are sequentially stacked on the second region on the back side; finally, a first electrode is formed on the side of the first passivation structure away from the first doped polysilicon layer, and a second electrode is formed on the side of the transparent conductive layer away from the doped conductive layer. This method sets different film structures in the first and second regions on the back side of the substrate, forming a hybrid back-contact solar cell. The first region on the back side uses a tunneling oxide layer, a first doped polycrystalline silicon layer, and a first passivation structure as a buffer film layer, ensuring good passivation effect in the first region and avoiding reflection loss caused by setting a transparent conductive layer in the first region. This is beneficial to improving the conversion efficiency of the back-contact solar cell. Moreover, the first passivation structure includes a first porous layer with multiple pores, which increases the effective optical path after light enters the cell from the front, thereby improving light utilization and improving the cell conversion efficiency. The second region on the back side uses a stack of hydrogenated silicon oxide structure, doped conductive layer, and transparent conductive layer, which achieves both efficient passivation and ensures good conductivity.

[0098] In some embodiments, a hydrogenated silicon oxide structure, a doped conductive layer, and a transparent conductive layer are sequentially stacked in the second region, including: sequentially stacking multiple hydrogenated silicon oxide layers and the doped conductive layer in the second region using a chemical vapor deposition process, wherein the multiple hydrogenated silicon oxide layers constitute the hydrogenated silicon oxide structure, and the oxygen content in the multiple hydrogenated silicon oxide layers exhibits a trend of first increasing and then decreasing along the direction away from the second region; and forming the transparent conductive layer on the surface of the doped conductive layer away from the hydrogenated silicon oxide layer using a physical vapor deposition process. In this embodiment, the method forms a stepped wide-bandgap hydrogenated silicon oxide layer stack structure, replacing the narrow-bandgap intrinsic amorphous silicon hydrogenated layer, which can effectively suppress epitaxial growth that is detrimental to the crystalline silicon substrate and enhance the passivation effect.

[0099] In other embodiments, the back side further includes an insulating region located between the first region and the second region. A tunneling oxide layer, a first doped polysilicon layer, and a first passivation structure are sequentially stacked in the first region, including: forming the tunneling oxide layer in the first region; forming a polysilicon thin film on the surface of the tunneling oxide layer away from the substrate using a low-pressure chemical vapor deposition process; performing a phosphorus diffusion process and an oxidation process on the polysilicon thin film sequentially to form a stacked first doped polysilicon layer and a phosphosilicate glass layer on the tunneling oxide layer, the thickness of the phosphosilicate glass layer being 60~100nm; texturing the first region, the insulating region, and the front side to form a textured structure, and pre-cleaning and alkaline washing the battery structure with the textured structure to remove the phosphosilicate glass layer; and forming the first passivation structure on the front side and the first doped polysilicon layer using an atomic layer deposition process. In this embodiment, by employing a tunneling oxide layer, a first doped polycrystalline silicon layer, and a first passivation structure in the first region on the back side, combined with the setting of an insulating region, and the application of texturing, cleaning, and ALD processes, charge collection and transport can be further enhanced, and the photoelectric conversion efficiency of the battery can be further improved.

[0100] Furthermore, in this application, the fabrication temperature of the first passivation structure on the first region is higher than the fabrication temperature of the hydrogenated silicon oxide structure on the second region. That is, the passivation structure on the first region is fabricated using a high-temperature process, while the passivation structure on the second region is fabricated using a low-temperature process. By combining high and low temperature processes, the bottleneck of passivation of purely high-temperature structures on the back side is overcome, and the high-temperature process in the fabrication of back-contact solar cells is reduced.

[0101] For example, the preparation method described in this application may specifically include the following steps:

[0102] 1) Provide raw silicon wafers, clean the raw silicon wafers, remove surface stains and impurities, and polish the cleaned raw silicon wafers. Divide the back of the polished silicon wafers into N-region (i.e., the first region), P-region (i.e., the second region) and Gap region (i.e., the insulating region).

[0103] 2) A polycrystalline silicon layer with a thickness of approximately 60~200nm is prepared on the back side of a silicon wafer using low-pressure chemical vapor deposition (LPCVD) technology;

[0104] 3) A phosphorus diffusion process is performed on the polycrystalline silicon layer to form an N-type doped polycrystalline silicon layer. The diffusion process adopts an oxidation-diffusion-oxidation method to form a protective phosphosilicate glass (PSG) layer with a thickness of about 60~100nm to prevent N-Poly from being damaged in subsequent wet processes.

[0105] 4) Use laser technology to remove the PSG layer mask and N-type doped polysilicon in the back gap region and P region. The N-type doped polysilicon in the N region forms the first doped polysilicon layer.

[0106] 5) Perform chain acid washing on the battery to remove the coating or wrap-around coating formed on the front of the battery during the preparation of the N-type doped polycrystalline silicon layer, ensuring the cleanliness of the substrate surface.

[0107] 6) Applying flocking technology to form a flocked surface structure in the front and back Gap and P areas;

[0108] 7) After depositing a silicon nitride layer on the front side and another silicon nitride layer on the back side, annealing is performed in a gaseous N2 atmosphere. The purpose is to activate the high-temperature structure, optimize hydrogen release, and further improve the passivation effect.

[0109] 8) The aluminum oxide layer and silicon nitride layer covering the P area on the back side are removed again by laser to prepare the surface for subsequent processing of the P area. The aluminum oxide layer and silicon nitride layer retained in the N area form the first passivation structure.

[0110] 9) Ensure high cleanliness of the P area on the back side through cleaning to eliminate residue;

[0111] 10) Use chemical vapor deposition (CVD) technology to form multiple intrinsic hydrogenated silicon oxide (ia-SiO:H) layers and P-type doped hydrogenated amorphous silicon (Pa-Si:H) layers (or hydrogenated microcrystalline silicon layers, hydrogenated nanocrystalline silicon layers); specifically, in the process of preparing ia-SiO:H layers, the hydrogen dilution ratio is 8~12, the pressure in the reaction chamber is 50~180pa, the oxygen doping ratio is 5%~10%, the substrate temperature is 180~230℃, and the oxygen source can be CO2, N2O, etc.

[0112] 11) Use laser to remove the ia-SiO:H layer and Pa-Si:H layer on the N region and Gap region to facilitate the establishment of subsequent metal contacts. The remaining ia-SiO:H layer in the P region forms a hydrogenated silicon oxide structure, and the remaining Pa-Si:H layer in the P region forms a doped conductive layer.

[0113] 12) Remove any residue from the laser treatment through cleaning to keep the surface clean;

[0114] 13) A transparent conductive oxide, such as indium tin oxide, is deposited on the back side using physical vapor deposition (PVD) technology to create good electrical contact;

[0115] 14) Use a laser to remove the transparent conductive oxides on the N-region and Gap region to form a precise electrode pattern (i.e., a transparent conductive layer). Alternatively, selectively protect the P-region outside the N-region and Gap region, use inkjet printing technology to determine the removal area of ​​the transparent conductive oxides, and then apply acid etching to remove the transparent conductive oxides in the N-region and Gap region, leaving the transparent conductive oxides (i.e., the transparent conductive layer) in the P-region unaffected, in preparation for electrode fabrication.

[0116] 15) Use laser or printing technology to fabricate metal electrodes in the N and P regions to obtain the first electrode and the second electrode, forming the final back contact structure. After the electrode fabrication is completed, perform light injection testing to evaluate the cell performance and ensure that the fabricated back contact solar cell meets the expected photoelectric conversion efficiency standard.

[0117] In this application, the N-region on the back side of the back-contact solar cell uses either a SiO (silicon oxide) + N-poly (N-type polycrystalline silicon) + AlO (aluminum oxide) + SiN (silicon nitride) film or a SiO (silicon oxide) + N-poly (N-type polycrystalline silicon) + SiO (silicon oxide) + N-poly (N-type polycrystalline silicon) + AlO (aluminum oxide) + SiN (silicon nitride) film as a buffer layer between the electrode and the passivation layer. Compared with conventional HBC (Heterojunction Back Contact) or N-poly combined with TCO structures, this design enhances the passivation effect and reduces the reflection loss caused by TCO. The presence of the alumina layer increases the effective optical path after light enters the cell from the textured surface, improving light utilization. Furthermore, during the fabrication process of the back-contact solar cell in this application, the cell film is hydrogen-treated to passivate cell defects and improve the turn-on voltage. In this application, the P-region on the back side of the back-contact solar cell employs an intrinsic hydrogenated silicon oxide multilayer stack + P-type amorphous / microcrystalline / nanocrystalline layer (stacked or single-layer) + a transparent conductive layer (TCO, AZO, ITO, etc.). Utilizing the low-temperature passivation advantages of amorphous and microcrystalline materials, the open-circuit voltage of the cell is increased, and the transparent conductive film layer reduces lateral transport resistance. In this application, the GAP region on the back side of the back-contact solar cell uses alumina + silicon nitride as the field passivation, hydrogen passivation, and surface protection structure for the cell. While improving the passivation performance of the cell, the alumina + silicon nitride film system, being an insulating layer, also significantly improves leakage between the N-region and P-region. This application uses a porous silicon nitride film layer on the surface, allowing for a higher effective optical path on the front side, increasing current; the metallized porous structure on the back side forms an embedded structure with the electrodes, improving the pull-out force between the electrodes and the cell substrate, while the non-metallized region enhances light absorption. This application employs a bottom SiN film system superimposed with a surface porous silicon nitride film system for passivation and antireflection processes. The dense bottom SiN film system ensures the passivation effect, while the surface porous silicon nitride film system further enhances the effective optical path and simultaneously strengthens the pull-out force of the low-temperature electrode.

[0118] In another aspect, this application provides a tandem battery, comprising: a back-contact solar cell, wherein the back-contact solar cell is any of the back-contact solar cells described above, or a back-contact solar cell prepared by any of the back-contact solar cell preparation methods described above; and a perovskite solar cell electrically connected to the back-contact solar cell.

[0119] In one embodiment, such as Figure 5 As shown, the stacked battery is a four-terminal stacked battery. In this stacked battery, the first electrode of the back-contact solar cell 100 and the first electrode of the perovskite cell 200 serve as two electrode terminals of the stacked battery, and the second electrode of the back-contact solar cell 100 and the second electrode of the perovskite cell 200 serve as the other two electrode terminals of the stacked battery.

[0120] In another embodiment, such as Figure 6 As shown, the tandem battery is a three-terminal tandem battery. In this tandem battery, the back-contact solar cell 100 serves as the bottom cell, and the perovskite cell 200 serves as the top cell. The top cell and the bottom cell can be connected by directly depositing the perovskite cell 200 on the surface of the back-contact solar cell 100. Figure 6 As shown, in this stacked cell, the first and second electrodes of the back-contact solar cell serve as the two electrode terminals of the stacked cell, and one electrode of the perovskite cell 200 serves as the other electrode terminal of the stacked cell.

[0121] In another embodiment, such as Figure 7 As shown, the stacked battery is a two-terminal stacked battery. In this stacked battery, the first electrode of the back-contact solar cell 100 and the first electrode of the perovskite cell 200 are electrically connected to serve as one electrode terminal of the stacked battery, and the first electrode and the second electrode of the back-contact solar cell are electrically connected to serve as the other electrode terminal of the stacked battery.

[0122] Another aspect of this application embodiment also provides a photovoltaic module, such as... Figure 8 As shown, the photovoltaic module includes: a battery string 300, which is formed by connecting multiple back-contact solar cells as described in any one of the methods, or back-contact solar cells prepared by any one of the methods described in the method ...

[0123] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0124] As can be seen from the above description, the embodiments described in this application achieve the following technical effects:

[0125] In the back-contact solar cell of this application, different film structures are used in the first and second regions on the back side of the substrate to form a hybrid back-contact solar cell. The first region on the back side uses a tunneling oxide layer, a first doped polycrystalline silicon layer, and a first passivation structure as a buffer film layer, which ensures good passivation effect in the first region and avoids reflection loss caused by setting a transparent conductive layer in the first region. This is beneficial to improving the conversion efficiency of the back-contact solar cell. Moreover, the first passivation structure includes a first porous layer with multiple pores, which increases the effective optical path after light enters the cell from the front, thereby improving light utilization and improving the cell conversion efficiency. The second region on the back side uses a stack of hydrogenated silicon oxide structure, doped conductive layer, and transparent conductive layer, which achieves both efficient passivation and ensures good conductivity.

[0126] 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 back-contact solar cell, characterized in that, include: The substrate includes a front side and a back side, the back side including a first region and a second region; A tunneling oxide layer, a first doped polysilicon layer, and a first passivation structure are stacked in the first region. The first passivation structure includes a first porous layer with multiple pores. The hydrogenated silicon oxide structure, the doped conductive layer, and the transparent conductive layer are stacked in the second region. The doped conductive layer has a different doping type than the first doped polycrystalline silicon layer. The doped conductive layer is a doped amorphous silicon layer. Along the direction from the second region to the transparent conductive layer, the oxygen content in the hydrogenated silicon oxide structure first increases and then decreases. The first electrode is located on the side of the first passivation structure away from the first doped polysilicon layer and is electrically connected to the first doped polysilicon layer. The second electrode is located on the side of the transparent conductive layer away from the doped conductive layer and is electrically connected to the doped conductive layer.

2. The back-contact solar cell according to claim 1, characterized in that, The first passivation structure further includes: The first silicon oxide layer is located between the first doped polycrystalline silicon layer and the first porous layer; The second doped polysilicon layer is located between the first silicon oxide layer and the first porous layer, and the doping type of the second doped polysilicon layer is the same as that of the first doped polysilicon layer. The first alumina layer is located between the second doped polycrystalline silicon layer and the first porous layer; The first silicon nitride layer is located between the first aluminum oxide layer and the first porous layer.

3. The back-contact solar cell according to claim 2, characterized in that, The substrate has the same doping type as the first doped polysilicon layer, and the doping concentration of the substrate, the doping concentration of the first doped polysilicon layer, and the doping concentration of the second doped polysilicon layer increase sequentially.

4. The back-contact solar cell according to claim 1, characterized in that, The first passivation structure further includes: The second alumina layer is located between the first doped polycrystalline silicon layer and the first porous layer; The second silicon nitride layer is located between the second aluminum oxide layer and the first porous layer.

5. The back-contact solar cell according to any one of claims 2 to 4, characterized in that, A portion of the first electrode is located within a portion of the hole.

6. The back-contact solar cell according to claim 1, characterized in that, The hydrogenated silicon oxide structure includes multiple hydrogenated silicon oxide layers stacked between the second region and the doped conductive layer, wherein the oxygen content in the multiple hydrogenated silicon oxide layers first increases and then decreases along the direction away from the second region.

7. The back-contact solar cell according to claim 6, characterized in that, Of the plurality of hydrogenated silicon oxide layers, the hydrogenated silicon oxide layer in contact with the second region is an intrinsic hydrogenated silicon oxide layer.

8. The back-contact solar cell according to claim 1, characterized in that, The back surface also includes an insulating region located between the first region and the second region, and the back contact solar cell further includes: The third alumina layer is located in the insulating region; A hydrogenated silicon nitride layer is located on the side of the third alumina layer away from the insulating region.

9. The back-contact solar cell according to claim 8, characterized in that, The first area is a polished surface, while the second area, the insulating area, and the front surface have a velvety structure.

10. The back-contact solar cell according to claim 1, characterized in that, The back-contact solar cell also includes: A second passivation structure is located on the front side, and the second passivation structure includes a second porous layer having a plurality of pores.

11. A method for fabricating a back-contact solar cell, characterized in that, A method for preparing a back-contact solar cell according to any one of claims 1 to 10, comprising: A substrate is provided, comprising an opposing front and a back side, the back side comprising a first region and a second region; A tunneling oxide layer, a first doped polysilicon layer, and a first passivation structure are sequentially stacked in the first region. The first passivation structure includes a first porous layer with multiple pores. In the second region, a hydrogenated silicon oxide structure, a doped conductive layer, and a transparent conductive layer are stacked sequentially. The doped conductive layer has a different doping type than the first doped polycrystalline silicon layer. A first electrode is formed on the side of the first passivation structure away from the first doped polysilicon layer, such that the first electrode is electrically connected to the first doped polysilicon layer. A second electrode is formed on the side of the transparent conductive layer away from the doped conductive layer, such that the second electrode is electrically connected to the doped conductive layer.

12. The method for fabricating a back-contact solar cell according to claim 11, characterized in that, In the second region, a hydrogenated silicon oxide structure, a doped conductive layer, and a transparent conductive layer are sequentially stacked, including: Multiple hydrogenated silicon oxide layers and the doped conductive layer are sequentially stacked in the second region using a chemical vapor deposition process. The multiple hydrogenated silicon oxide layers constitute the hydrogenated silicon oxide structure. The oxygen content in the multiple hydrogenated silicon oxide layers first increases and then decreases along the direction away from the second region. The transparent conductive layer is formed on the surface of the doped conductive layer away from the hydrogenated silicon oxide layer using a physical vapor deposition process.

13. The method for fabricating a back-contact solar cell according to claim 11, characterized in that, The back side also includes an insulating region located between the first region and the second region. A tunneling oxide layer, a first doped polysilicon layer, and a first passivation structure are sequentially stacked in the first region, including: The tunneling oxide layer is formed in the first region; A polycrystalline silicon thin film is formed on the surface of the tunneling oxide layer away from the substrate using a low-pressure chemical vapor deposition process; The polycrystalline silicon thin film is subjected to phosphorus diffusion and oxidation processes in sequence to form a stacked first doped polycrystalline silicon layer and a phosphorus silicon glass layer on the tunneling oxide layer, wherein the thickness of the phosphorus silicon glass layer is 60~100nm. The first area, the insulating area, and the front surface are texturized to form a textured structure, and the battery structure with the textured structure is pre-cleaned and alkaline washed to remove the phosphosilicate glass layer. The first passivation structure is formed on the front side and the first doped polysilicon layer using an atomic layer deposition process.

14. A stacked battery, characterized in that, include: A back-contact solar cell, wherein the back-contact solar cell is the back-contact solar cell according to any one of claims 1 to 10, or the back-contact solar cell prepared by the method of preparing the back-contact solar cell according to any one of claims 11 to 13; The perovskite cell is electrically connected to the back-contact solar cell.

15. A photovoltaic module, characterized in that, include: A battery string is formed by connecting multiple back-contact solar cells as described in any one of claims 1 to 10, or back-contact solar cells prepared by the method described in any one of claims 11 to 13, or stacked cells as described in claim 14. 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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