Solar cell and method for manufacturing the same

Abstract

The present application provides a solar cell and a manufacturing method thereof. The solar cell includes: a substrate having a front surface and a back surface; an emitter located on a first region and a second region; a doped conductive layer located on a third region and a fourth region; a first passivation layer located on a partial surface of the emitter away from the substrate, and the projection of the first passivation layer on the substrate is located in the first region; a second passivation layer located on a partial surface of the doped conductive layer away from the substrate, and the projection on the substrate is located in the third region; a conductive thin film located on the partial surfaces of the emitter and the doped conductive layer away from the substrate, and the projection on the substrate is located in the second region and the fourth region; a first paste layer located on a side of the conductive thin film away from the emitter and the doped conductive layer; and a second paste layer located on a side of the first paste layer away from the conductive thin film. The present application solves the problem that the contact resistance of the solar cell in the prior art is relatively large, affecting the conversion efficiency of the cell.

Description

Technical Field

[0001] This application relates to the field of solar cells, and more particularly, to a solar cell and a method for manufacturing the same. Background Art

[0002] In recent years, with the increasing global demand for renewable energy, the development of solar cell technology has become an important research direction in the energy field. Tunnel Oxide Passivated Contact (TOPCon) solar cells, with their high efficiency and stability, have become one of the mainstream products in the current market. However, there are still technical bottlenecks on the road to higher efficiency. In the manufacturing process of existing Topcon solar cells, in order to improve the cell efficiency, the sheet resistance of boron doping has been continuously pushed up, and at the same time, the control strategy of silver paste single consumption is more and more inclined to save materials, which leads to the increasingly prominent problem of contact resistance in the metallization process. Specifically, with the increase of sheet resistance and the decrease of silver paste single consumption, the contact between the metal grid line and the cell surface becomes unsatisfactory, and the contact resistance increases significantly, thus limiting the further improvement of cell efficiency. Summary of the Invention

[0003] The main object of this application is to provide a solar cell and a method for manufacturing the same, so as to at least solve the problem that the contact resistance of the solar cell in the prior art is large and affects the cell conversion efficiency.

[0004] To achieve the above object, according to one aspect of this application, a solar cell is provided, including: a substrate having a front surface and a back surface, the front surface of the substrate having a first region and a second region, the back surface of the substrate having a third region and a fourth region, the second region being located on at least one side of the first region, the fourth region being located on at least one side of the third region; an emitter located on the first region and the second region; a doped conductive layer located on the third region and the fourth region; a first passivation layer located on a partial surface of the emitter away from the substrate, the projection of the first passivation layer on the substrate being located in the first region; a second passivation layer located on a partial surface of the doped conductive layer away from the substrate, the projection of the second passivation layer on the substrate being located in the third region; a conductive thin film located on the partial surfaces of the emitter and the doped conductive layer away from the substrate, the projection of the conductive thin film on the substrate being located in the second region and the fourth region; a first paste layer located on a side of the conductive thin film away from the emitter and the doped conductive layer; a second paste layer located on a side of the first paste layer away from the conductive thin film, the materials of the conductive thin film, the second paste layer, and the first paste layer being different.

[0005] Optionally, the first paste layer includes silver paste structures extending in a first direction and spaced apart in a second direction. The silver paste structures include silver paste portions and blank portions alternately arranged in the first direction, or the silver paste structures include silver paste lines extending in the first direction. The first direction intersects the second direction. Wherein, the length of the silver paste line in the first direction is greater than the length of the silver paste portion in the first direction, and the thickness and / or line width of the silver paste line is less than the thickness and / or line width of the silver paste portion.

[0006] Optionally, the thickness of the silver paste line is 1 - 5 μm, and the line width is 10 - 30 μm.

[0007] Optionally, the width of the second region in a predetermined direction is 50 - 100 μm, and the predetermined direction is parallel to the line width direction of the silver paste line and the silver paste portion.

[0008] Optionally, the material of the conductive thin film includes ITO (Indium Tin Oxide), the material of the first paste layer includes silver, and the material of the second paste layer includes base metals.

[0009] According to another aspect of the present application, there is provided a method for manufacturing a solar cell, including: providing a cell intermediate member, the cell intermediate member including a substrate having a front surface and a back surface, an emitter, a doped conductive layer, a first passivation layer, and a second passivation layer. The front surface of the substrate has a first region and a second region, the back surface of the substrate has a third region and a fourth region, the second region is located on at least one side of the first region, the fourth region is located on at least one side of the third region, the emitter is located on the first region and the second region, the doped conductive layer is located on the third region and the fourth region, the first passivation layer is located on a partial surface of the emitter away from the substrate, and the projection of the first passivation layer on the substrate is located in the first region. The second passivation layer is located on a partial surface of the doped conductive layer away from the substrate, and the projection of the second passivation layer on the substrate is located in the third region; forming a conductive thin film, a first paste layer, and a second paste layer on the partial surfaces of the emitter and the doped conductive layer away from the substrate. The projection of the conductive thin film on the substrate is located in the second region and the fourth region. The first paste layer is located on a side of the conductive thin film away from the emitter and the doped conductive layer, and the second paste layer is located on a side of the first paste layer away from the conductive thin film. The materials of the conductive thin film, the second paste layer, and the first paste layer are different.

[0010] Optionally, forming a conductive thin film, a first paste layer, and a second paste layer on the emitter and a partial surface of the doped conductive layer away from the substrate includes: forming an initial conductive thin film on the emitter and the surface of the doped conductive layer away from the substrate; removing a part of the initial conductive thin film so that a part of the emitter and a part of the doped conductive layer are exposed, and the remaining initial conductive thin film forms the conductive thin film; screen-printing a first paste on the surface of the conductive thin film away from the emitter and the doped conductive layer to form the first paste layer; and printing a first paste on the surface of the first paste layer away from the conductive thin film to form the second paste layer.

[0011] Optionally, forming the initial conductive thin film on the emitter and the surface of the doped conductive layer away from the substrate includes: forming the initial conductive thin film on the emitter and the surface of the doped conductive layer away from the substrate by physical vapor deposition magnetron sputtering method; removing a part of the initial conductive thin film so that a part of the emitter and a part of the doped conductive layer are exposed, and the remaining initial conductive thin film forms the conductive thin film, including: forming a sacrificial layer on the surface of the initial conductive thin film away from the emitter and the doped conductive layer, and the projection of the sacrificial layer on the substrate overlaps with the second region and the fourth region respectively; using the sacrificial layer as a mask, removing the exposed initial conductive thin film with an infrared laser with a wavelength of 3-5 μm to obtain the conductive thin film; and removing the sacrificial layer.

[0012] Optionally, screen-printing the first paste on the surface of the conductive thin film away from the emitter and the doped conductive layer to form the first paste layer includes one of the following: screen-printing silver paste on the surface of the conductive thin film away from the second region to form a silver paste structure extending in a first direction and spaced apart in a second direction, the silver paste structure including silver paste portions and blank portions alternately arranged in the first direction, and the first direction intersects with the second direction; screen-printing silver paste on the surface of the conductive thin film away from the second region to form a silver paste structure extending in a first direction and spaced apart in a second direction, the silver paste structure including silver paste lines extending in the first direction, wherein the length of the silver paste lines in the first direction is greater than the length of the silver paste portions in the first direction, and the thickness and / or line width of the silver paste lines is less than the thickness and / or line width of the silver paste portions.

[0013] Optionally, a battery middleware is provided, including: providing a silicon wafer and texturing the front and back surfaces of the silicon wafer; performing ion diffusion on the front surface of the textured silicon wafer to form the emitter; stacking a tunneling oxide layer and an amorphous silicon layer on the back surface of the silicon wafer, and doping and annealing the amorphous silicon layer to obtain the doped conductive layer; forming a first initial passivation layer on the surface of the emitter away from the silicon wafer, and forming a second initial passivation layer on the surface of the doped conductive layer away from the tunneling oxide layer; using a laser to remove part of the first initial passivation layer and part of the second initial passivation layer, so that part of the emitter and part of the doped conductive layer are exposed, and the remaining first initial passivation layer forms the first passivation layer, and the remaining second initial passivation layer forms the second passivation layer.

[0014] Applying the technical solution of the present application, an emitter is formed on the front surface of the substrate, a doped conductive layer is formed on the back surface of the substrate, a first passivation layer is formed on a partial surface of the emitter away from the substrate, the projection of the first passivation layer is located in a first area on the front surface of the substrate, a second passivation layer is formed on a partial surface of the doped conductive layer away from the substrate, the projection of the second passivation layer is located in a third area on the back surface of the substrate, a conductive thin film, a first paste layer and a second paste layer are formed on the partial surfaces of the emitter and the doped conductive layer away from the substrate, so that the conductive thin film is in direct contact with the emitter and the doped conductive layer respectively, and the projections of the conductive thin film, the first paste layer and the second paste layer are located in a second area and a fourth area of the substrate. Compared with the way of forming an electrode on the passivation layer, where the electrode contacts the emitter or the doped conductive layer through the passivation layer, in the present application, the electrodes of the solar cell including the conductive thin film, the first paste layer and the second paste layer are in direct contact with the emitter and the doped conductive layer respectively, and the ohmic contact effect is better, which can reduce the contact resistance of the solar cell, thus being beneficial to the improvement of the battery conversion efficiency. Description of the Drawings

[0015] The specification drawings forming a part of the present application are used to provide a further understanding of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation to the present application. In the drawings:

[0016] Figure 1 It shows a schematic cross-sectional structure diagram of a solar cell provided in an embodiment of the present application;

[0017] Figure 2 It shows a schematic flow chart of a manufacturing method of a solar cell provided in an embodiment of the present application;

[0018] Figure 3 It shows a manufacturing flow chart of a solar cell provided in an embodiment of the present application.

[0019] Among them, the accompanying drawings include the following reference numerals:

[0020] 10. Substrate; 11. Emitter; 12. Doped conductive layer; 13. First passivation layer; 14. Second passivation layer; 15. Conductive thin film; 16. First paste layer; 17. Second paste layer; 18. Tunneling oxide layer. Detailed implementation manners

[0021] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The following will describe the present application in detail with reference to the accompanying drawings and in combination with the embodiments.

[0022] In order to enable those skilled in the art to better understand the solution of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0023] It should be noted that the terms "first", "second", etc. in the specification, claims and drawings of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so as to describe the embodiments of the present application here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0024] As introduced in the background art, there is a problem in the prior art that the contact resistance of a solar cell is relatively large, which affects the conversion efficiency of the cell. To solve the above technical problems, the embodiments of the present application provide a solar cell and a manufacturing method thereof.

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention.

[0026] The embodiments of the present application provide a solar cell. Figure 1 Exemplarily, a schematic cross-sectional structure diagram of a solar cell provided by the embodiments of the present application is shown, as Figure 1 shown, the solar cell includes:

[0027] Substrate 10, having a front side and a back side, the front side of the substrate 10 having a first region and a second region, the back side of the substrate 10 having a third region and a fourth region, the second region being located on at least one side of the first region, and the fourth region being located on at least one side of the third region;

[0028] Emitter 11, located on the first region and the second region;

[0029] Doped conductive layer 12, located on the third region and the fourth region;

[0030] First passivation layer 13, located on a partial surface of the emitter 11 away from the substrate 10, and the projection of the first passivation layer 13 on the substrate 10 is located in the first region;

[0031] Second passivation layer 14, located on a partial surface of the doped conductive layer 12 away from the substrate 10, and the projection of the second passivation layer 14 on the substrate 10 is located in the third region;

[0032] Conductive thin film 15, located on a partial surface of the emitter 11 and the doped conductive layer 12 away from the substrate 10, and the projection of the conductive thin film 15 on the substrate 10 is located in the second region and the fourth region;

[0033] First paste layer 16, located on a side of the conductive thin film 15 away from the emitter 11 and the doped conductive layer 12;

[0034] Specifically, the projection of the first paste layer 16 on the substrate 10 is located in the second region and the fourth region.

[0035] Second paste layer 17, located on a side of the first paste layer 16 away from the conductive thin film 15, and the materials of the conductive thin film 15, the second paste layer 17, and the first paste layer 16 are different.

[0036] Specifically, the projection of the second paste layer 17 on the substrate 10 is located in the second region and the fourth region. The electrode of the solar cell includes the conductive thin film 15, the first paste layer 16, and the second paste layer 17. Both the front side and the back side of the substrate 10 have the conductive thin film 15, the first paste layer 16, and the second paste layer.

[0037] Through the above embodiments, an emitter is formed on the front surface of the substrate, a doped conductive layer is formed on the back surface of the substrate, a first passivation layer is formed on a partial surface of the emitter away from the substrate, and the projection of the first passivation layer is located in a first region on the front surface of the substrate. A second passivation layer is formed on a partial surface of the doped conductive layer away from the substrate, and the projection of the second passivation layer is located in a third region on the back surface of the substrate. A conductive thin film, a first paste layer, and a second paste layer are formed on the partial surfaces of the emitter and the doped conductive layer away from the substrate, such that the conductive thin film is in direct contact with the emitter and the doped conductive layer respectively. The projections of the conductive thin film, the first paste layer, and the second paste layer are located in a second region and a fourth region of the substrate. Compared with the way of forming an electrode on the passivation layer, where the electrode is in contact with the emitter or the doped conductive layer through the passivation layer, in this application, the electrodes of the solar cell, including the conductive thin film, the first paste layer, and the second paste layer, are in direct contact with the emitter and the doped conductive layer respectively, and the ohmic contact effect is better, which can reduce the contact resistance of the solar cell, thereby being beneficial to the improvement of the cell conversion efficiency.

[0038] The solar cell of this application can be a TOPCon cell. In some alternative embodiments, the solar cell can be a single-sided cell, that is, it receives solar light only through the first surface of the substrate 10. In some other alternative embodiments, the solar cell can be a double-sided cell, that is, it receives solar light through the front and back surfaces of the substrate 10.

[0039] Specifically, there can be one first region and one second region respectively, and the second region is located on one side of the first region; there can be multiple first regions and multiple second regions respectively, and the first regions and the second regions are alternately arranged at intervals in a certain direction. There can be one third region and one fourth region respectively, and the fourth region is located on one side of the third region; there can be multiple third regions and multiple fourth regions respectively, and the third regions and the fourth regions are alternately arranged at intervals in a certain direction.

[0040] The second region and the fourth region are also called the metal grid line regions, which are the regions where the projections of the electrodes of the solar cell are located on the substrate 10. The areas of the second region and the fourth region are greater than or equal to the projected areas of the electrodes on the second region and the fourth region. The first region and the third region are also called the non-metal grid line regions, which are the regions on the front and back surfaces of the substrate 10 except for the second region and the fourth region.

[0041] The first passivation layer 13 and the second passivation layer 14 of the present application can play a passivation role. The first passivation layer 13 and the second passivation layer 14 can also reduce the reflection of incident light on the front and / or back of the substrate 10. The first passivation layer 13 and the second passivation layer 14 can be a single-layer film structure or a multi-layer film structure. The material of the first passivation layer 13 can specifically include at least one of magnesium fluoride, silicon oxide, aluminum oxide, silicon oxynitride, silicon nitride, and titanium oxide. The material of the second passivation layer 14 can specifically include at least one of magnesium fluoride, silicon oxide, aluminum oxide, silicon oxynitride, silicon nitride, and titanium oxide. The materials of the first passivation layer 13 and the second passivation layer 14 can be the same or different.

[0042] In an alternative embodiment, the material of one of the conductive thin film, the first paste layer, and the second paste layer includes silver. The material of one of the three includes silver, and the materials of the other two do not include silver. In this way, compared with the method of using silver paste as a solar electrode, in the solar cell of the present application, in addition to silver paste, other conductive materials are also used as electrode materials, reducing the amount of silver paste used in the electrode, thereby achieving the effect of reducing the manufacturing cost of the battery.

[0043] According to some other exemplary embodiments of the present application, the first paste layer 16 includes silver paste structures extending in a first direction and spaced apart in a second direction. The silver paste structures include silver paste portions and blank portions alternately arranged in the first direction, or the silver paste structures include silver paste lines extending in the first direction. The first direction intersects the second direction. Among them, the length of the silver paste line in the first direction is greater than the length of the silver paste portion in the first direction, and the thickness and / or line width of the silver paste line is less than the thickness and / or line width of the silver paste portion. In the present application, multiple silver paste portions can be intermittently wired on the conductive thin film according to different virtual-real ratios, further reducing the amount of silver paste used while maintaining sufficient conductivity, reducing silver paste consumption, and thus further reducing the production cost of the battery; in the present application, silver paste lines can also be wired in the form of continuous solid lines. Since the number of silver paste lines is less than that of silver paste portions, and the amount of silver paste consumed is fixed, at least one of the thickness and line width of the silver paste line is less than that of the silver paste portion. In this way, it can not only ensure that the amount of silver paste used is small, but also because the solid line wiring has good current conductivity, it can effectively reduce the contact resistance, providing a stable and efficient current collection and transmission path for the solar cell, and further ensuring the photoelectric conversion efficiency of the battery.

[0044] In a specific embodiment, the ratio of the length of the silver paste portion in the first direction to the length of the blank portion in the first direction can be 0.2:0.8, 0.3:0.7, 0.4:0.6, 0.5:0.5, 0.6:0.4, 0.7:0.3, or 0.8:0.2, etc.

[0045] In some embodiments, the thickness of the silver paste portion is 4 - 5 μm, and the line width of the silver paste portion is 10 - 15 μm.

[0046] In a specific embodiment, the thickness of the silver paste line is 1 - 5 μm, and the line width is 10 - 30 μm. For example, the thickness of the silver paste line can be 1 μm, 2 μm, 3 μm, 4 μm, or 5 μm, etc., and the line width of the silver paste line can be 10 μm, 15 μm, 20 μm, 25 μm, or 30 μm, etc. Such a size design can not only ensure good electrical contact but also reduce the usage amount of silver paste, lower the production cost of the battery, and is applicable to the production of solar cells of various scales. Especially in large-scale industrial production, it can effectively control costs and improve economic benefits.

[0047] In the embodiments of the present application, the first silver paste layer selects an ultra-thin silver paste seed layer, whose thickness and line width are much smaller than those of the traditional silver paste layer, which can greatly save silver paste materials and reduce production costs. The silver paste seed layer can form a good ohmic contact with the battery surface, which is the basis for efficient current transmission of the battery. Even if the silver paste seed layer is very thin, it can provide sufficient conductivity to ensure the smooth flow of current without affecting the photoelectric conversion efficiency of the battery. Moreover, the combined use of the silver paste seed layer, the conductive thin film 15, and the second paste layer 17 can form a thicker metal layer on the basis of the silver paste seed layer, thereby enhancing the stability of the metallization structure of the solar cell.

[0048] Optionally, the width of the second region in the predetermined direction is 50 - 100 μm, and the predetermined direction is parallel to the line width direction of the silver paste line and the silver paste portion. For example, the width of the second region in the predetermined direction can be 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, or 100 μm, etc. Such a size of the second region can not only ensure that there is sufficient contact area between the emitter and the conductive thin film, and between the doped conductive layer and the conductive thin film, thereby further reducing the contact resistance, but also will not overly occupy the effective photoelectric conversion area of the solar cell, and is applicable to the design of various solar cells. Especially in a high-density battery array, it can maintain good photoelectric conversion efficiency.

[0049] Exemplarily, the material of the conductive thin film 15 includes ITO, the material of the first paste layer 16 includes silver, and the material of the second paste layer 17 includes base metals. The combination of ITO, silver paste, and base metals can greatly reduce the unit consumption of silver paste while achieving good ohmic contact.

[0050] Specifically, the base metals include but are not limited to nickel, copper, aluminum, molybdenum, tin and titanium. The use of base metals is intended to reduce the use of precious metals in the production process of solar cells, reduce costs, and maintain or improve the performance of the cells. By precisely controlling the printing process of base metals, good contact with the cell surface can be achieved, promoting the effective collection and transmission of current, thereby improving the overall efficiency and economy of solar cells.

[0051] In a more specific embodiment, the conductive film 15 is an ITO film, the first slurry layer 16 is a silver paste seed layer, and the second slurry layer 17 is a base metal layer.

[0052] In some embodiments, the conductive film 15, the first slurry layer 16, and the second slurry layer 17 located on the front side of the substrate 10 constitute a first electrode, and the conductive film 15, the first slurry layer 16, and the second slurry layer 17 located on the back side of the substrate 10 constitute a second electrode. The first electrode and the second electrode may be one or more. The first electrode is in direct contact with the emitter 11 located on the front side of the substrate 10 to form an electrical connection. The second electrode is in direct contact with the doped conductive layer 12 located on the back side of the substrate 10 to form an electrical connection.

[0053] In the present application, the doping type of the emitter 11 is different from the doping type of the substrate 10, so that the emitter 11 and the substrate 10 form a PN junction. When it is on, a new - ,exist Under the action of the built-in electric field, photogenerated holes flow to the P region, and photogenerated electrons flow to the N region. When the circuit is connected, current is generated, thereby realizing the photoelectric conversion function of the solar cell. The doped conductive layer 12 located on the back side of the substrate 10 can be a doped silicon layer, and the doping type of the doped silicon layer is the same as the doping type of the substrate 10. The doped conductive layer 12 can form field passivation. The doping type of the doped conductive layer 12 can be the same as the doping type of the substrate 10. The material of the doped conductive layer 12 can specifically include doped polycrystalline silicon, doped microcrystalline silicon or doped amorphous silicon.

[0054] Exemplarily, the substrate 10 may be an N-type semiconductor substrate, that is, the substrate 10 is doped with N-type ions, and the N-type ions may specifically be phosphorus, arsenic, or antimony. The emitter 11 may be a P-type emitter, that is, the emitter 11 is doped with P-type ions, and the P-type ions may be boron, aluminum, or gallium. The emitter 11 may be obtained by diffusing and doping P-type ions on the front surface of the N-type semiconductor substrate 10, and the doped part of the substrate 10 is converted into the emitter 11. The doped conductive layer 12 is an N-type conductive layer, doped with N-type ions, and the N-type ions may specifically be any one of phosphorus, arsenic, or antimony.

[0055] According to some other optional solutions of the present application, the solar cell further includes a tunneling oxide layer 18, and the tunneling oxide layer 18 is located between the doped conductive layer 12 and the back surface of the substrate 10. The tunneling oxide layer 18 can achieve the effect of chemical passivation of the substrate 10. In addition, the tunneling oxide layer 18 can cause an asymmetric shift in the energy band on the back surface of the substrate 10, such that the barrier for majority carriers in the carriers is lower than the barrier for minority carriers in the carriers. Therefore, the majority carriers can more easily perform quantum tunneling through the tunneling oxide layer 18, while the minority carriers are difficult to pass through the tunneling oxide layer 18 to achieve selective transport of carriers. The material of the tunneling oxide layer 18 may be a dielectric material, such as silicon oxide.

[0056] In some embodiments, the substrate 10 can receive incident light and generate photo-generated carriers. The substrate 10 may be a silicon substrate 10, and the material of the silicon substrate 10 may include single-crystalline silicon, polycrystalline silicon, amorphous silicon, and microcrystalline silicon, etc.

[0057] Those skilled in the art can set the morphology of the front and back surfaces of the substrate 10 according to actual needs. In some embodiments, the front surface of the substrate 10 may be set as a pyramid-shaped textured surface, so that the reflectivity of the front surface of the substrate 10 to incident light is small, thereby having a large absorption and utilization rate of light. The back surface of the substrate 10 may be set as a non-pyramid-shaped textured surface, such as a stacked stepped morphology, so that the tunneling oxide layer 18 located on the back surface has a high density and uniformity, and the tunneling oxide layer 18 has a good passivation effect on the back surface of the substrate 10. The back surface of the substrate 10 may also be set as a pyramid-shaped textured surface.

[0058] It should be noted that other film layers may be provided between the front surface of the substrate 10 and the emitter 11, and the emitter 11 may also be in contact with the front surface of the substrate 10; other film layers may be provided between the back surface of the substrate 10 and the doped conductive layer 12, and the doped conductive layer 12 may also be in contact with the back surface of the substrate 10; other film layers may be provided between the emitter 11 and the first passivation layer 13, and the emitter 11 may also be in contact with the first passivation layer 13; other film layers may be provided between the doped conductive layer 12 and the second passivation layer 14, and the doped conductive layer 12 may also be in contact with the second passivation layer 14; other film layers may be provided between the conductive thin film 15 and the first paste layer 16, and the conductive thin film 15 may also be in contact with the first paste layer 16, and other film layers may be provided between the first paste layer 16 and the second paste layer 17, and the first paste layer 16 may also be in contact with the second paste layer 17.

[0059] An embodiment of the present application also provides a method for manufacturing a solar cell, and the method for manufacturing the solar cell is used to manufacture and form any one of the solar cells. Figure 2 It is a flowchart of the method for manufacturing a solar cell according to an embodiment of the present application. As Figure 2 shown, the method includes the following steps:

[0060] Step S201, providing a battery intermediate, the battery intermediate includes a substrate 10 having a front surface and a back surface, an emitter 11, a doped conductive layer 12, a first passivation layer 13 and a second passivation layer 14. The front surface of the substrate 10 has a first region and a second region, and the back surface of the substrate 10 has a third region and a fourth region. The second region is located on at least one side of the first region, and the fourth region is located on at least one side of the third region. The emitter 11 is located on the first region and the second region, the doped conductive layer 12 is located on the third region and the fourth region, the first passivation layer 13 is located on a partial surface of the emitter 11 away from the substrate 10, and the projection of the first passivation layer 13 on the substrate 10 is located in the first region. The second passivation layer 14 is located on a partial surface of the doped conductive layer 12 away from the substrate 10, and the projection of the second passivation layer 14 on the substrate 10 is located in the third region;

[0061] Step S202: A conductive thin film 15, a first paste layer 16, and a second paste layer 17 are formed on partial surfaces of the emitter 11 and the doped conductive layer 12 away from the substrate 10. The projection of the conductive thin film 15 on the substrate 10 is located in the second region and the fourth region. The first paste layer 16 is located on a side of the conductive thin film 15 away from the emitter 11 and the doped conductive layer 12. The second paste layer 17 is located on a side of the first paste layer 16 away from the conductive thin film 15. The materials of the conductive thin film 15, the second paste layer 17, and the first paste layer 16 are different.

[0062] Specifically, the projection of the first paste layer 16 on the substrate 10 is located in the second region and the fourth region; the projection of the second paste layer 17 on the substrate 10 is located in the second region and the fourth region. The electrodes of the solar cell include the conductive thin film 15, the first paste layer 16, and the second paste layer 17. Both the front side and the back side of the substrate 10 have the conductive thin film 15, the first paste layer 16, and the second paste layer.

[0063] Through the embodiment, first, a battery middleware is provided. In the battery middleware, an emitter is formed on the front surface of the substrate, a doped conductive layer is formed on the back surface of the substrate, a first passivation layer is formed on a partial surface of the emitter away from the substrate, and the projection of the first passivation layer is located in the first region on the front surface of the substrate. A second passivation layer is formed on a partial surface of the doped conductive layer away from the substrate, and the projection of the second passivation layer is located in the third region on the back surface of the substrate. Then, a conductive thin film, a first paste layer, and a second paste layer are formed on partial surfaces of the emitter and the doped conductive layer away from the substrate, so that the conductive thin film is in direct contact with the emitter and the doped conductive layer respectively. The projections of the conductive thin film, the first paste layer, and the second paste layer are located in the second region and the fourth region of the substrate. Compared with the way of forming electrodes on the passivation layer and the electrodes are in contact with the emitter or the doped conductive layer through the passivation layer, in this application, the electrodes of the solar cell including the conductive thin film, the first paste layer, and the second paste layer are in direct contact with the emitter and the doped conductive layer respectively, and the ohmic contact effect is better, which can reduce the contact resistance of the solar cell, thus being beneficial to the improvement of the battery conversion efficiency.

[0064] In an alternative embodiment, a conductive thin film, a first paste layer, and a second paste layer are formed on the emitter and a partial surface of the doped conductive layer away from the substrate, including: forming an initial conductive thin film on the emitter and the surface of the doped conductive layer away from the substrate; removing a part of the initial conductive thin film so that a part of the emitter and a part of the doped conductive layer are exposed, and the remaining initial conductive thin film forms the conductive thin film, wherein the projection of the removed initial conductive thin film on the substrate is located in the first region and the third region, and the projection of the remaining initial conductive thin film (i.e., the conductive thin film) on the substrate is located in the second region and the fourth region; screen-printing a first paste on the surface of the conductive thin film away from the emitter and the doped conductive layer to form the first paste layer; printing a first paste on the surface of the first paste layer away from the conductive thin film to form the second paste layer. In this embodiment, by removing a part of the initial conductive thin film, the influence of the initial conductive thin film on the light transmittance of the first region and the third region of the substrate is avoided, thereby affecting the absorption of incident light by the substrate; then, the first paste layer and the second paste layer are sequentially printed on the remaining initial conductive thin film, while further ensuring the conductivity and stability of the solar cell electrode, a substantial reduction in the single consumption of silver paste is achieved.

[0065] According to some exemplary embodiments, forming an initial conductive thin film on the emitter and the surface of the doped conductive layer away from the substrate includes: forming the initial conductive thin film on the emitter and the surface of the doped conductive layer away from the substrate by physical vapor deposition magnetron sputtering. Removing a part of the initial conductive thin film so that a part of the emitter and a part of the doped conductive layer are exposed, and the remaining initial conductive thin film forms the conductive thin film, including: forming a sacrificial layer on the surface of the initial conductive thin film away from the emitter and the doped conductive layer, and the projection of the sacrificial layer on the substrate overlaps with the second region and the fourth region respectively; using the sacrificial layer as a mask, removing the exposed initial conductive thin film with an infrared laser having a wavelength of 3-5 μm to obtain the conductive thin film; removing the sacrificial layer. In this embodiment, an initial conductive thin film can be uniformly deposited on the surfaces of the emitter and the doped conductive layer by physical vapor deposition magnetron sputtering; the initial conductive thin film in the first region and the third region can be precisely removed by infrared laser in cooperation with the sacrificial layer, and this process ensures the existence of the conductive thin film projected on the second region and the fourth region of the substrate to promote the adhesion of the subsequent paste and form a high-quality ohmic contact, while avoiding unnecessary shielding of the first region and the third region of the substrate by the conductive thin film and maintaining the high photoelectric conversion efficiency of the battery.

[0066] Exemplarily, the material of the conductive thin film 15 includes ITO, the material of the first paste layer 16 includes silver, and the material of the second paste layer 17 includes base metal. The combination of ITO, silver paste, and base metal can greatly reduce the single consumption of silver paste while achieving good ohmic contact.

[0067] Since the light transmittance of ITO is 80% - 90%, in order to avoid ITO affecting the absorption of incident light by the substrate, part of the ITO thin film needs to be removed to expose the first region.

[0068] In some other exemplary embodiments, screen-printing the first paste on the surface of the conductive thin film away from the emitter and the doped conductive layer to form the first paste layer includes one of the following: screen-printing silver paste on the surface of the conductive thin film away from the second region to form a silver paste structure extending in a first direction and spaced apart in a second direction, the silver paste structure including silver paste portions and blank portions alternately arranged in the first direction, the first direction intersecting the second direction; screen-printing silver paste on the surface of the conductive thin film away from the second region to form a silver paste structure extending in a first direction and spaced apart in a second direction, the silver paste structure including silver paste lines extending in the first direction, wherein the length of the silver paste lines in the first direction is greater than the length of the silver paste portions in the first direction, and the thickness and / or line width of the silver paste lines are less than the thickness and / or line width of the silver paste portions. In the present application, multiple silver paste portions can be intermittently wired on the conductive thin film according to different virtual-real ratios, further reducing the amount of silver paste used while maintaining sufficient conductivity, reducing silver paste consumption, and thus further reducing the production cost of the battery; in the present application, a continuous solid-line form can also be used to wire the silver paste lines. Since the number of silver paste lines is less than that of the silver paste portions, and with a fixed amount of silver paste consumed, at least one of the thickness and line width of the silver paste lines is less than that of the silver paste portions. In this way, not only can the amount of silver paste used be ensured to be less, but also because the solid-line wiring has good current conduction, it can effectively reduce the contact resistance, providing a stable and efficient current collection and transmission path for the solar cell, and further ensuring the photoelectric conversion efficiency of the battery.

[0069] In the present application, a low-temperature silver paste ultra-thin seed layer is screen-printed to form the first paste layer.

[0070] The thickness of the silver paste line is 1-5 μm, and the line width is 10-30 μm. For example, the thickness of the silver paste line can be 1 μm, 2 μm, 3 μm, 4 μm, or 5 μm, etc., and the line width of the silver paste line can be 10 μm, 15 μm, 20 μm, 25 μm, or 30 μm, etc. Such a dimension design can not only ensure good electrical contact but also reduce the usage amount of silver paste, lower the production cost of the battery, and is applicable to the production of solar cells of various scales. Especially in large-scale industrial production, it can effectively control costs and improve economic benefits.

[0071] In some embodiments, a battery middleware is provided, including: providing a silicon wafer and texturing the front and back surfaces of the silicon wafer; performing ion diffusion on the front surface of the textured silicon wafer to form the emitter, and the silicon wafer except the emitter constitutes the substrate; stacking a tunneling oxide layer and an amorphous silicon layer on the back surface of the silicon wafer, and doping and annealing the amorphous silicon layer to obtain the doped conductive layer; forming a first initial passivation layer on the surface of the emitter away from the silicon wafer, and forming a second initial passivation layer on the surface of the doped conductive layer away from the tunneling oxide layer; using a laser to remove part of the first initial passivation layer and part of the second initial passivation layer, so that part of the emitter and part of the doped conductive layer are exposed, and the remaining first initial passivation layer forms the first passivation layer, and the remaining second initial passivation layer forms the second passivation layer. In this embodiment, first, initial passivation layers are respectively formed on the emitter on the front surface of the substrate and the doped conductive layer on the back surface of the substrate, and then part of the initial passivation layer is removed by a laser opening film method, which is convenient for subsequent formation of electrodes directly contacting the emitter and the doped conductive layer, thereby achieving better ohmic contact and improving the conversion efficiency of the solar cell.

[0072] Hereinafter, the solar cell of the present application will be specifically described with reference to specific examples and comparative examples.

[0073] Example 1

[0074] This embodiment provides a solar cell, including:

[0075] A substrate having a front surface and a back surface, the front surface of the substrate having a first region and a second region, the back surface of the substrate having a third region and a fourth region, the second region being located on at least one side of the first region, the fourth region being located on at least one side of the third region, and the widths of the second region and the fourth region in a predetermined direction being 75 μm;

[0076] An emitter located on the first region and the second region;

[0077] A doped conductive layer located on the third region and the fourth region;

[0078] The first passivation layer is located on a partial surface of the emitter away from the substrate, and a projection of the first passivation layer on the substrate is located in the first region;

[0079] The second passivation layer is located on a partial surface of the doped conductive layer away from the substrate, and a projection of the second passivation layer on the substrate is located in the third region;

[0080] The conductive thin film is located on partial surfaces of the emitter and the doped conductive layer away from the substrate, a projection of the conductive thin film on the substrate is located in the second region and the fourth region, and the conductive thin film is an ITO thin film;

[0081] The first paste layer is located on a side of the conductive thin film away from the emitter and the doped conductive layer; the first paste layer is a plurality of silver paste lines, the thickness of the silver paste lines is 3 μm, the line width is 20 μm, and the line width direction of the silver paste lines is parallel to a predetermined direction;

[0082] The second paste layer is located on a side of the first paste layer away from the conductive thin film, and the second paste layer is a base metal layer.

[0083] Example 2

[0084] The present application provides a solar cell, and the only difference between this solar cell and Example 1 is that the thickness of the silver paste lines is 1 μm.

[0085] Example 3

[0086] The present application provides a solar cell, and the only difference between this solar cell and Example 1 is that the thickness of the silver paste lines is 5 μm.

[0087] Example 4

[0088] The present application provides a solar cell, and the only difference between this solar cell and Example 1 is that the line width of the silver paste lines is 10 μm.

[0089] Example 5

[0090] The present application provides a solar cell, and the only difference between this solar cell and Example 1 is that the line width of the silver paste lines is 30 μm.

[0091] Example 6

[0092] The present application provides a solar cell, and the only difference between this solar cell and Example 1 is that the width of the second region in the predetermined direction is 50 μm.

[0093] Example 7

[0094] The present application provides a solar cell, and the only difference between this solar cell and that of Embodiment 1 is that the width of the second region in a predetermined direction is 100 μm.

[0095] Embodiment 8

[0096] This embodiment provides a solar cell, comprising:

[0097] A substrate having a front surface and a back surface. The front surface of the substrate has a first region and a second region, the back surface of the substrate has a third region and a fourth region, the second region is located on at least one side of the first region, and the fourth region is located on at least one side of the third region;

[0098] An emitter located on the first region and the second region;

[0099] A doped conductive layer located on the third region and the fourth region;

[0100] A first passivation layer located on a partial surface of the emitter away from the substrate, and the projection of the first passivation layer on the substrate is located in the first region;

[0101] A second passivation layer located on a partial surface of the doped conductive layer away from the substrate, and the projection of the second passivation layer on the substrate is located in the third region;

[0102] A conductive thin film located on a partial surface of the emitter and the doped conductive layer away from the substrate, and the projection of the conductive thin film on the substrate is located in the second region and the fourth region, and the conductive thin film is an ITO thin film;

[0103] A first paste layer located on a side of the conductive thin film away from the emitter and the doped conductive layer; a silver paste structure extending along a first direction and arranged at intervals along a second direction, the silver paste structure comprising silver paste portions and blank portions alternately arranged along the first direction, the ratio of the length of the silver paste portions in the first direction to the length of the blank portions in the first direction being 0.7:0.3, the thickness of the silver paste portions being 5 μm, and the line width being 13 μm;

[0104] A second paste layer located on a side of the first paste layer away from the conductive thin film, and the second paste layer is a base metal layer.

[0105] Embodiment 9

[0106] The present application provides a solar cell, and the only difference between this solar cell and that of Embodiment 8 is that the ratio of the length of the silver paste portions to the length of the blank portions is 0.5:0.5.

[0107] Embodiment 10

[0108] This application provides a solar cell. The only difference between this solar cell and Example 8 is that the length ratio of the silver paste part to the blank part is 0.4:0.6.

[0109] Comparative Example 1

[0110] This embodiment provides a solar cell, including:

[0111] A substrate having a front side and a back side;

[0112] An emitter located on the front side of the substrate;

[0113] A doped conductive layer located on the back side of the substrate;

[0114] A first passivation layer located on the side of the emitter away from the substrate;

[0115] A second passivation layer located on the side of the doped conductive layer away from the substrate;

[0116] A silver paste layer located on the side of the passivation layer away from the doped conductive layer.

[0117] Comparative Example 2

[0118] This application provides a solar cell. The only difference between this solar cell and Example 1 is that the thickness of the silver paste line is 0.3 μm.

[0119] Comparative Example 3

[0120] This application provides a solar cell. The only difference between this solar cell and Example 1 is that the thickness of the silver paste line is 7 μm.

[0121] Comparative Example 4

[0122] This application provides a solar cell. The only difference between this solar cell and Example 1 is that the line width of the silver paste line is 8 μm.

[0123] Comparative Example 5

[0124] This application provides a solar cell. The only difference between this solar cell and Example 1 is that the line width of the silver paste line is 35 μm.

[0125] Comparative Example 6

[0126] This application provides a solar cell. The only difference between this solar cell and Example 1 is that the width of the second region in a predetermined direction is 40 μm.

[0127] Comparative Example 7

[0128] The present application provides a solar cell, and the only difference between this solar cell and that in Embodiment 1 is that the width of the second region in a predetermined direction is 120 μm.

[0129] Comparative Example 8

[0130] The present application provides a solar cell, and the only difference between this solar cell and that in Embodiment 8 is that the thickness of the silver paste part is 5 μm and the line width is 20 μm.

[0131] Comparative Example 9

[0132] The present application provides a solar cell, and the only difference between this solar cell and that in Embodiment 8 is that the thickness of the silver paste part is 7 μm and the line width is 25 μm.

[0133] Comparative Example 10

[0134] The present application provides a solar cell, and the only difference between this solar cell and that in Embodiment 8 is that the thickness of the silver paste part is 9 μm and the line width is 28 μm.

[0135] The performance of the solar cells in the above-mentioned Embodiments 1 to 7 and Comparative Examples 1 to 7 was tested, and the test results are shown in Table 1 as follows:

[0136] Table 1

[0137]

[0138] It can be seen from the experimental data that the series resistance in Embodiment 1 is significantly lower than that in Comparative Example 1, and the photoelectric conversion efficiency in Embodiment 1 is significantly higher than that in Comparative Example 1, indicating that the solar cell of the present application can effectively reduce the contact resistance of the solar cell and improve the photoelectric conversion efficiency. It can be seen from the experimental data that the silver paste weight in Embodiments 2 - 5 is significantly lower than that in Comparative Examples 3 and 5, indicating that the solar cell of the present application can effectively reduce the manufacturing cost of the solar cell. The series resistance in Embodiment 6 is lower than the contact resistance in Comparative Example 6, and the photoelectric conversion efficiency in Embodiment 6 is higher than that in Comparative Example 6, indicating that too small a width of the second region will cause a large contact resistance, thereby affecting the cell conversion efficiency. The photoelectric conversion efficiency in Embodiment 7 is higher than that in Comparative Example 7, indicating that too large a width of the second region will reduce the effective photoelectric conversion area of the solar cell, thereby affecting the cell conversion efficiency.

[0139] The performance of the solar cells in the above-mentioned Embodiments 8 to 10 and Comparative Examples 8 to 10 was tested, and the test results are shown in Table 2 as follows:

[0140] Table 2

[0141]

[0142] As can be seen from the experimental data, the silver paste weight in Examples 8 to 10 is significantly lower than that in Comparative Examples 8 to 10, indicating that the solar cell of the present application can effectively reduce the manufacturing cost of solar cells.

[0143] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the implementation process of the manufacturing method of the solar cell of the present application will be described in detail below in conjunction with specific embodiments.

[0144] This embodiment relates to a specific manufacturing method of a solar cell, as Figure 3 shown, including the following steps:

[0145] Step S1: Texturing: First, the surface of the silicon wafer is textured to increase the surface roughness, which helps to improve the light absorption efficiency of the cell;

[0146] Step S2: Boron diffusion: Boron diffusion is performed on the front side of the silicon wafer to form a p-type emitter;

[0147] Step S3: Alkaline polishing: Through alkaline polishing, impurities and oxide layers on the surface of the silicon wafer are removed to provide a clean and flat surface for subsequent processing;

[0148] Step S4: LPCVD (Low Pressure Chemical Vapor Deposition): Deposit a layer of amorphous silicon or microcrystalline silicon on the back side of the silicon wafer;

[0149] Step S5: Phosphorus diffusion: Phosphorus diffusion is performed on the back side of the cell to form an n-type doped silicon layer, which is the doped conductive layer on the back side of the cell;

[0150] Step S6: Removal of overplating: Remove the P-type and N-type layers at the edge of the cell to avoid short circuits;

[0151] Step S7: ALD (Atomic Layer Deposition): Deposit a layer of aluminum oxide passivation layer;

[0152] Step S8: Front film and back film: Use ALD technology to deposit a tunneling oxide layer on the front and back sides of the cell to obtain the passivation layers on the front and back sides of the cell;

[0153] Step S9: Laser opening of the film: Use laser to open the film on the front and back sides to precisely remove the coverage of the passivation layer in the metal grid line area and prepare for the subsequent metallization process;

[0154] Step S10: Preparation of conductive thin film by PVD: Use physical vapor deposition (PVD) magnetron sputtering technology to deposit a layer of ITO conductive thin film on the front and back sides of the cell. This layer of thin film has good light transmittance and conductivity and is the basis for the subsequent metallization layer;

[0155] Step S11: Laser removal of the non-metal grid conductive film: Use the laser again. This time, it is to remove the ITO conductive film covering in the non-metal grid area, and keep the width of the ITO conductive film in the metal grid area as 50 - 100 μm to optimize the current transmission path and reduce light shielding.

[0156] Step S12: Screen printing: On the remaining ITO film, first screen print a low-temperature silver paste ultra-thin seed layer with a thickness of 1 - 5 μm and a width of 10 - 30 μm. This seed layer can be continuously distributed or solid-line distributed according to different virtual-real ratios to reduce the consumption of silver paste. Subsequently, continue to screen print the base metal paste on the seed layer to form a complete electrode and achieve better ohmic contact.

[0157] Step S13: IV test: Finally, conduct an IV (current-voltage) characteristic test on the solar cell to evaluate the photoelectric conversion efficiency and performance of the cell.

[0158] In the manufacturing process of the solar cell in this application, by adding the preparation of the ITO conductive film and laser etching, as well as an innovative multi-layer metallization method on the basis of the existing technology, the problems of reducing the contact resistance and reducing the use of silver paste are effectively solved, providing a new solution for the further efficiency improvement and cost control of Topcon solar cells.

[0159] It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. And although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0160] It should also be noted that the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. Without more limitations, the element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, commodity or device including the element.

[0161] From the above description, it can be seen that the embodiments described in this application achieve the following technical effects:

[0162] 1), For the solar cell of the present application, an emitter is formed on the front surface of the substrate, a doped conductive layer is formed on the back surface of the substrate, a first passivation layer is formed on a partial surface of the emitter away from the substrate, the projection of the first passivation layer is located in a first area on the front surface of the substrate, a second passivation layer is formed on a partial surface of the doped conductive layer away from the substrate, the projection of the second passivation layer is located in a third area on the back surface of the substrate, a conductive thin film, a first paste layer and a second paste layer are formed on the partial surfaces of the emitter and the doped conductive layer away from the substrate, such that the conductive thin film is in direct contact with the emitter and the doped conductive layer respectively, and the projections of the conductive thin film, the first paste layer and the second paste layer are located in a second area and a fourth area of the substrate. Compared with the way of forming an electrode on the passivation layer where the electrode contacts the emitter or the doped conductive layer through the passivation layer, in the present application, the electrodes of the solar cell including the conductive thin film, the first paste layer and the second paste layer are in direct contact with the emitter and the doped conductive layer respectively, and the ohmic contact effect is better, which can reduce the contact resistance of the solar cell, thus being beneficial to the improvement of the cell conversion efficiency.

[0163] 2), For the manufacturing method of the solar cell of the present application, first, a cell intermediate is provided. In the cell intermediate, an emitter is formed on the front surface of the substrate, a doped conductive layer is formed on the back surface of the substrate, a first passivation layer is formed on a partial surface of the emitter away from the substrate, the projection of the first passivation layer is located in a first area on the front surface of the substrate, a second passivation layer is formed on a partial surface of the doped conductive layer away from the substrate, the projection of the second passivation layer is located in a third area on the back surface of the substrate; then, a conductive thin film, a first paste layer and a second paste layer are formed on the partial surfaces of the emitter and the doped conductive layer away from the substrate, such that the conductive thin film is in direct contact with the emitter and the doped conductive layer respectively, and the projections of the conductive thin film, the first paste layer and the second paste layer are located in a second area and a fourth area of the substrate. Compared with the way of forming an electrode on the passivation layer where the electrode contacts the emitter or the doped conductive layer through the passivation layer, in the present application, the electrodes of the solar cell including the conductive thin film, the first paste layer and the second paste layer are in direct contact with the emitter and the doped conductive layer respectively, and the ohmic contact effect is better, which can reduce the contact resistance of the solar cell, thus being beneficial to the improvement of the cell conversion efficiency.

[0164] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A solar cell, characterized in that, Comprising: A substrate having a front side and a back side, the front side of the substrate having a first region and a second region, the back side of the substrate having a third region and a fourth region, the second region being located on at least one side of the first region, and the fourth region being located on at least one side of the third region; An emitter located on the first region and the second region; A doped conductive layer located on the third region and the fourth region; A first passivation layer located on a partial surface of the emitter away from the substrate, and a projection of the first passivation layer on the substrate being located in the first region; A second passivation layer located on a partial surface of the doped conductive layer away from the substrate, and a projection of the second passivation layer on the substrate being located in the third region; A conductive thin film located on partial surfaces of the emitter and the doped conductive layer away from the substrate, and a projection of the conductive thin film on the substrate being located in the second region and the fourth region; A first paste layer located on a side of the conductive thin film away from the emitter and the doped conductive layer; A second paste layer located on a side of the first paste layer away from the conductive thin film, and materials of the conductive thin film, the second paste layer, and the first paste layer being different.

2. The solar cell according to claim 1, characterized in that, The first paste layer includes silver paste structures extending in a first direction and spaced apart in a second direction, the silver paste structures including silver paste portions and blank portions alternately arranged in the first direction, or the silver paste structures include silver paste lines extending in the first direction, the first direction intersecting the second direction, wherein a length of the silver paste line in the first direction is greater than a length of the silver paste portion in the first direction, and a thickness and / or line width of the silver paste line is less than a thickness and / or line width of the silver paste portion.

3. The solar cell according to claim 2, wherein The silver paste line has a thickness of 1 to 5 μm and a line width of 10 to 30 μm.

4. The solar cell according to claim 2, characterized in that, A width of the second region in a predetermined direction is 50 to 100 μm, and the predetermined direction is parallel to a line width direction of the silver paste line and the silver paste portion.

5. The solar cell according to any one of claims 1 to 4, characterized in that, The material of the conductive thin film includes ITO, the material of the first paste layer includes silver, and the material of the second paste layer includes base metals.

6. A method for manufacturing a solar cell, characterized in that, Comprising: Providing a battery middleware, the battery middleware including a substrate having a front side and a back side, an emitter, a doped conductive layer, a first passivation layer, and a second passivation layer, the front side of the substrate having a first region and a second region, the back side of the substrate having a third region and a fourth region, the second region being located on at least one side of the first region, the fourth region being located on at least one side of the third region, the emitter being located on the first region and the second region, the doped conductive layer being located on the third region and the fourth region, the first passivation layer being located on a partial surface of the emitter away from the substrate, a projection of the first passivation layer on the substrate being located in the first region, the second passivation layer being located on a partial surface of the doped conductive layer away from the substrate, and a projection of the second passivation layer on the substrate being located in the third region; A conductive thin film, a first paste layer, and a second paste layer are formed on the emitter and a partial surface of the doped conductive layer away from the substrate. A projection of the conductive thin film on the substrate is located in the second region and the fourth region. The first paste layer is located on a side of the conductive thin film away from the emitter and the doped conductive layer. The second paste layer is located on a side of the first paste layer away from the conductive thin film. Materials of the conductive thin film, the second paste layer, and the first paste layer are different.

7. The method according to claim 6, characterized in that, Forming a conductive thin film, a first paste layer, and a second paste layer on the emitter and a partial surface of the doped conductive layer away from the substrate includes: Forming an initial conductive thin film on the emitter and a surface of the doped conductive layer away from the substrate; Removing a part of the initial conductive thin film so that a part of the emitter and a part of the doped conductive layer are exposed, and the remaining initial conductive thin film forms the conductive thin film; Screen-printing a first paste on a surface of the conductive thin film away from the emitter and the doped conductive layer to form the first paste layer; Printing a second paste on a surface of the first paste layer away from the conductive thin film to form the second paste layer.

8. The method according to claim 7, wherein Forming an initial conductive thin film on the emitter and a surface of the doped conductive layer away from the substrate includes: forming the initial conductive thin film on the emitter and a surface of the doped conductive layer away from the substrate by using physical vapor deposition magnetron sputtering method. Removing a part of the initial conductive thin film so that a part of the emitter and a part of the doped conductive layer are exposed, and the remaining initial conductive thin film forms the conductive thin film includes: forming a sacrificial layer on a surface of the initial conductive thin film away from the emitter and the doped conductive layer. A projection of the sacrificial layer on the substrate overlaps with the second region and the fourth region respectively; using the sacrificial layer as a mask, removing the exposed initial conductive thin film by using an infrared laser with a wavelength of 3-5 μm to obtain the conductive thin film; removing the sacrificial layer.

9. The method according to claim 7, wherein Screen-printing a first paste on a surface of the conductive thin film away from the emitter and the doped conductive layer to form the first paste layer includes one of the following: Screen-printing a silver paste on a surface of the conductive thin film away from the second region to form a silver paste structure extending in a first direction and spaced apart in a second direction. The silver paste structure includes silver paste portions and blank portions alternately arranged in the first direction. The first direction intersects with the second direction; Screen-printing a silver paste on a surface of the conductive thin film away from the second region to form a silver paste structure extending in a first direction and spaced apart in a second direction. The silver paste structure includes silver paste lines extending in the first direction. Wherein, a length of the silver paste lines in the first direction is greater than a length of the silver paste portions in the first direction, and a thickness and / or a line width of the silver paste lines is less than a thickness and / or a line width of the silver paste portions.

10. The method according to any one of claims 6 to 9, characterized in that, Providing a battery middle piece, including: Provide a silicon wafer and texture the front and back surfaces of the silicon wafer; Perform ion diffusion on the front surface of the textured silicon wafer to form the emitter; Stack a tunneling oxide layer and an amorphous silicon layer on the back surface of the silicon wafer, and dope and anneal the amorphous silicon layer to obtain the doped conductive layer; Form a first initial passivation layer on the surface of the emitter away from the silicon wafer, and form a second initial passivation layer on the surface of the doped conductive layer away from the tunneling oxide layer; Use a laser to remove part of the first initial passivation layer and part of the second initial passivation layer, so that part of the emitter and part of the doped conductive layer are exposed, and the remaining first initial passivation layer forms the first passivation layer, and the remaining second initial passivation layer forms the second passivation layer.

Images