Solar cell and method of manufacturing the same, photovoltaic module

Abstract

The embodiment of the present application relates to the field of photovoltaics, and provides a solar cell, a preparation method thereof and a photovoltaic module, which can at least improve the cell efficiency. The solar cell comprises: a substrate having a front surface and a back surface arranged oppositely; a back type layer located on the surface of the substrate; the back type layer comprises a first back type layer located on the front surface corresponding to the metal region; a first electrode located on the substrate corresponding to the metal region and electrically connected with the first back type layer; a passivation contact structure located on the back surface of the metal region; and a second electrode located on the passivation contact structure corresponding to the metal region and electrically connected with the passivation contact structure.

Description

Technical Field

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

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

[0003] Current solar cells mainly include IBC cells (Interdigitated Back Contact), TOPCON (Tunnel Oxide Passivated Contact) cells, PERC cells (Passivated emitter and real cell), and heterojunction cells. Different film layer configurations and functional limitations are used to reduce optical losses and decrease photogenerated carrier recombination on and within the silicon substrate, thereby improving the photoelectric conversion efficiency of solar cells.

[0004] However, the current efficiency of solar cells is still unsatisfactory. Summary of the Invention

[0005] This application provides a solar cell and its preparation method, as well as a photovoltaic module, which at least helps to improve the cell efficiency of the solar cell.

[0006] According to some embodiments of this application, one aspect of this application provides a solar cell having a metal region and a non-metal region, comprising: a substrate having a front side and a back side disposed opposite to each other; an inversion layer located on the surface of the substrate; the inversion layer including a first inversion layer located on the front side corresponding to the metal region; a first electrode located on the substrate corresponding to the metal region and electrically connected to the first inversion layer; a passivation contact structure located on the back side of the metal region; and a second electrode located on the passivation contact structure corresponding to the metal region and electrically connected to the passivation contact structure.

[0007] In some embodiments, the inversion layer includes a second inversion layer located on the corresponding front side of a portion of the non-metallic region and connecting two adjacent first inversion layers.

[0008] In some embodiments, the inversion layer further includes a third inversion layer, which is located on the corresponding front side of the non-metallic region. The third inversion layer extends in the same direction as the first inversion layer and is located between adjacent first inversion layers. The third inversion layer is electrically connected to the second inversion layer.

[0009] In some embodiments, along the arrangement direction of the first electrode, the ratio of the total width of the orthographic projection of the first inversion layer and the third inversion layer on the front surface to the width of the front surface ranges from 3% to 40%, and / or, along the extension direction of the first electrode, the ratio of the total width of the orthographic projection of the second inversion layer on the front surface to the length of the front surface ranges from 2% to 20%.

[0010] In some embodiments, the orthographic projection of the passivation contact structure on the back side overlaps with the orthographic projection of the inversion layer on the back side; or, the orthographic projection of the passivation contact structure on the back side partially overlaps with the orthographic projection of the inversion layer on the back side, and the overlapping area is greater than or equal to 0.4 times the area of ​​the inversion layer.

[0011] In some embodiments, the distance between the surface of the substrate containing the inversion layer and the back surface is a first distance, and the distance between the surface of the substrate not containing the inversion layer and the back surface is a second distance, wherein the first distance is greater than the second distance.

[0012] According to some embodiments of this application, another aspect of this application provides a method for fabricating a solar cell, the solar cell having a metal region and a non-metal region, comprising: providing a substrate having a front side and a back side disposed opposite to each other; forming an inversion layer located on the front side of the substrate; the inversion layer including a first inversion layer located on the front side corresponding to the metal region; forming a first electrode located on the substrate corresponding to the metal region and electrically connected to the first inversion layer; forming a passivation contact structure located on the back side of the metal region; and forming a second electrode located on the passivation contact structure corresponding to the metal region and electrically connected to the passivation contact structure.

[0013] In some embodiments, the inversion layer further includes a second inversion layer, the front side includes a first processed region and a first unprocessed region, and the method for forming the inversion layer includes: performing a doping treatment on the front side of the substrate to convert a portion of the substrate thickness into a doped layer; removing the doped layer in the first processed region, and retaining the doped layer located in the first unprocessed region as an inversion layer, wherein the inversion layer located in the metal region is a first inversion layer, and the portion of the inversion layer located in the non-metal region is a second inversion layer.

[0014] In some embodiments, the front side includes a second processed region and a second unprocessed region, and the method for forming the inversion layer includes: performing laser doping on the second processed region of the substrate to convert a portion of the substrate into an inversion layer.

[0015] According to some embodiments of this application, another aspect of this application provides a photovoltaic module, including: a battery string, formed by connecting multiple solar cells as described in any one of the above embodiments or solar cells prepared by any one of the above embodiments; a connecting component for electrically connecting two adjacent solar cells; an encapsulating film for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulating film away from the battery string.

[0016] The technical solution provided in this application has at least the following advantages:

[0017] The solar cell provided in this application embodiment has an inversion layer disposed on the front side of the solar cell, and the inversion layer is partially located in the metal region and part of the non-metal region of the solar cell. The first inversion layer located in the metal region can form a low-resistance heavily doped region, reducing the metal recombination of the first electrode and the contact resistance between the first electrode and the first inversion layer. For the part of the non-metal region, no inversion layer is disposed, that is, no heavily doped region is disposed, thereby reducing the carrier recombination rate in the non-metal region on the front side.

[0018] In addition, a passivation contact structure is formed on the back side. The passivation contact structure is located on the metal region, which can ensure the passivation performance of the metal region and the heavy doping concentration of the region in contact with the second electrode. Attached Figure Description

[0019] 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.

[0020] Figure 1 This is a schematic diagram of a solar cell provided in an embodiment of this application;

[0021] Figure 2 for Figure 1 A sectional view along section A1-A2;

[0022] Figure 3This is a schematic diagram of another solar cell structure provided in an embodiment of this application;

[0023] Figure 4 A top view of an inversion layer in another type of solar cell provided in an embodiment of this application;

[0024] Figure 5 A top view of an inversion layer in another solar cell provided in an embodiment of this application;

[0025] Figure 6 for Figure 1 Another sectional view along section A1-A2;

[0026] Figures 7-15 This is a schematic diagram of the structure of a solar cell corresponding to each step in a method for preparing a solar cell according to another embodiment of this application;

[0027] Figure 16 A schematic diagram of a stacked battery provided in another embodiment of this application;

[0028] Figure 17 This is a schematic diagram of a photovoltaic module provided in one embodiment of this application;

[0029] Figure 18 for Figure 17 A schematic diagram of the cross-sectional structure along section M1-M2. Detailed Implementation

[0030] As can be seen from the background technology, the current efficiency of solar cells is not good.

[0031] This application provides a solar cell and its preparation method, as well as a photovoltaic module. By setting an inversion layer located in the metal region, the optical loss in the non-metal region is reduced and the contact performance between the electrode and the inversion layer is improved, thereby improving the cell efficiency.

[0032] 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.

[0033] 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.

[0034] 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: A exists, A and B exist simultaneously, and B exists. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0035] 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).

[0036] 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.

[0037] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0038] In the accompanying drawings corresponding to the embodiments of the wood 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] Figure 1 This is a schematic diagram of a solar cell provided in an embodiment of this application; Figure 2 for Figure 1 A sectional view along section A1-A2.

[0043] refer to Figure 1 and Figure 2According to some embodiments of this application, one aspect of this application provides a solar cell having a metal region 11 and a non-metal region 12. The solar cell includes: a substrate 100 having a front side 10 and a back side 20 disposed opposite to each other; an inversion layer 120 located on the front side 10 of the substrate 100; the inversion layer includes a first inversion layer 121 located on the front side 10 of the substrate 100 corresponding to the metal region 11; a first electrode 106 located on the substrate 100 corresponding to the metal region 11 and electrically connected to the first inversion layer 121; a passivation contact structure located on the back side 20 of the metal region 11; and a second electrode 116 located on the passivation contact structure corresponding to the metal region 11 and electrically connected to the passivation contact structure. Thus, an inversion layer 120 is provided on the front side 10 of the solar cell, and the inversion layer 120 is partially located in the metal region 11 and part of the non-metal region 12 of the solar cell. The first inversion layer 121 located in the metal region 11 can form a low-resistance heavily doped region, reducing the metal recombination of the first electrode 106 and the contact resistance between the first electrode 106 and the first inversion layer 121. The inversion layer 120 is not provided in the part of the non-metal region 12, that is, no heavily doped region is provided, thereby reducing the carrier recombination rate of the non-metal region 12 on the front side 10.

[0044] In addition, a passivation contact structure is formed on the back side 20. The passivation contact structure is located on the metal region 11, which can ensure the passivation performance of the region where the metal region 11 is located and the heavy doping concentration of the region in contact with the second electrode 116.

[0045] refer to Figure 2 In some embodiments, the material of the substrate 100 can be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon or germanium. The elemental semiconductor material can be monocrystalline, polycrystalline, amorphous, or microcrystalline (a state simultaneously possessing both monocrystalline and amorphous states is called microcrystalline). For example, silicon can be at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon.

[0046] In some embodiments, the substrate 100 may also be a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, silicon germanide, silicon carbide, gallium arsenide, indium gallium dihydrogen phosphate, perovskite, cadmium telluride, and copper indium selenide. The substrate 100 may also be a sapphire substrate, a silicon-on-insulator substrate, or a germanium-on-insulator substrate.

[0047] In some embodiments, the substrate 100 can be an N-type semiconductor substrate or a P-type semiconductor substrate. The N-type semiconductor substrate is doped with an N-type dopant element, which can be any one of group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type semiconductor substrate 100 is doped with a P-type dopant element, which can be any one of group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0048] In some embodiments, the substrate 100 has a front side 10 and a back side 20 disposed opposite to each other. The solar cell is a single-sided cell, with the front side 10 serving as the light-receiving surface for receiving incident light, and the back side 20 serving as the back-lighting surface. The back-lighting surface can also receive incident light, but its efficiency in receiving incident light is somewhat lower than that of the light-receiving surface.

[0049] In some embodiments, the metal region 11 refers to the area where the first electrode 106 is projected onto the substrate 100, and the non-metal region 12 refers to the area outside the projected area of ​​the first electrode 106 onto the substrate 100. To ensure that the film layer contacted by the first electrode 106 has a high doping concentration or that the area contacted by the first electrode 106 is a high-concentration inversion layer 120, the area of ​​the metal region 11 is generally set to be greater than or equal to the area of ​​the projected area of ​​the first electrode 106 onto the substrate 100.

[0050] In some embodiments, the doping element in the inversion layer 120 is different from the doping element in the substrate 100, and the inversion layer 120 is doped with either an N-type doping element or a P-type doping element.

[0051] In some embodiments, reference Figure 1 The width of the first inversion layer 121 along its arrangement direction ranges from 20 μm to 500 μm. This width range ensures that the area directly opposite the first electrode 106 is entirely composed of the first inversion layer 121, and that the region forming the PN junction—the area where electrons or holes are formed—is relatively large, resulting in higher battery efficiency. This width range also reduces the number of recombination centers formed by high doping concentrations on the substrate 100 surface, thus lowering the recombination carrier rate on the substrate 100 surface.

[0052] In some embodiments, the width of the first inversion layer 121 along the arrangement direction X of the first inversion layer 121 can be 20μm, 53μm, 88μm, 120μm, 210μm, 380μm or 500μm.

[0053] refer to Figure 3The inversion layer also includes a second inversion layer 122, which is located on the front side 10 of the substrate 100 corresponding to a portion of the non-metallic region 12 and connects to two adjacent first inversion layers 121. For the second inversion layer 122 located in the non-metallic region 12, connecting to two adjacent first inversion layers 121 enables electrical transmission between the two first inversion layers 121, reducing the lateral transmission resistance. Secondly, the second inversion layer 122 enables lateral transmission between electrodes. While ensuring strong lateral transmission capability, the distance between the two first electrodes 106 can be increased, thereby reducing the total number of first electrodes 106 on the front side 10 and thus reducing the shading area.

[0054] In some embodiments, the inversion layer 120 located in the metal region 11 can serve as an emitter, and the inversion layer 120 located in the non-metal region 12 can serve as a transport layer. The transport layer can improve the lateral transport capability between adjacent emitters, thereby improving battery efficiency. Specifically, the first inversion layer 121 located in the metal region 11 serves as an emitter, and the second inversion layer 122 located in the non-metal region 12 serves as a transport layer.

[0055] In some embodiments, reference Figure 4 The inversion layer 120 also includes a third inversion layer 123, which is located on the front side 10 of the substrate 100 corresponding to the non-metallic region 12. The extension direction of the third inversion layer 123 is the same as that of the first inversion layer 121, and it is located between adjacent first inversion layers 121. The third inversion layer 123 is electrically connected to the second inversion layer 122. The third inversion layer 123 serves as an emitter, increasing the region for electron and hole conversion, thereby improving battery efficiency.

[0056] In some embodiments, the number of third inversion layers 123 between adjacent first inversion layers 121 is 0 to 10. The number of third inversion layers 123 can increase the area of ​​the region where electrons and holes are converted. For the substrate 100 of the non-metallic region 12, the area of ​​the substrate 100 not covered by the inversion layer 120 can reduce the surface recombination rate of the substrate 100, thereby reducing the loss of the substrate 100 itself and improving the battery efficiency.

[0057] In some embodiments, the number of third inversion layers 123 between adjacent first inversion layers 121 can be 2, 5, 7 or 9.

[0058] In some embodiments, the width of the third inversion layer 123 along the arrangement direction of the first inversion layer 121 is a first width, and the width of the first inversion layer 121 along the arrangement direction of the first inversion layer 121 is a second width, wherein the first width is less than or equal to the second width. Thus, the third inversion layer 123 can be set relatively small, which can shorten the area transferred from two adjacent regions to the third inversion layer 123, and also avoid the problem of a large recombination rate on the surface of the substrate 100 caused by a large number of third inversion layers 123.

[0059] In some embodiments, the spacing between the first inversion layer 121 and the third inversion layer 123, or the spacing between two third inversion layers 123, can range from 100 μm to 1000 μm. The spacing can be 120 μm, 203 μm, 420 μm, 560 μm, 710 μm, 860 μm, or 980 μm.

[0060] In some embodiments, along the arrangement direction of the first electrode 106, the ratio of the total width of the orthographic projection of the first inversion layer 121 and the third inversion layer 123 onto the front side 10 to the width of the front side 10 ranges from 3% to 40%. This ensures that the area of ​​the inversion layer 120 is relatively large, with the larger region serving as the conversion region for photogenerated carriers, thereby achieving a larger open-circuit voltage and battery efficiency. Furthermore, the series resistance between the first electrode 106 and the inversion layer 120 is low, resulting in less electrical loss in the battery.

[0061] In some embodiments, the ratio of the total width of the orthographic projection of the first inversion layer 121 and the third inversion layer 123 onto the front side 10 to the width of the front side 10 can be 3%, 8%, 12%, 18%, 26%, 33%, 35%, or 39%.

[0062] In some embodiments, continue to refer to Figure 1 The width of the second inversion layer 122 along the extension direction of the first electrode 106 ranges from 50 μm to 600 μm. The width of the second inversion layer 122 along the extension direction Y of the first electrode 106 can be 53 μm, 88 μm, 120 μm, 210 μm, 380 μm, 500 μm, or 600 μm.

[0063] In some embodiments, along the extending direction of the first electrode 106, the ratio of the total width of the second inversion layer 122 projected onto the front side 10 to the length of the front side 10 ranges from 2% to 20%. The ratio of the total width of the second inversion layer 122 projected onto the front side 10 to the length of the front side 10 can be 3%, 5%, 6%, 8%, 12%, 15%, 18%, or 20%.

[0064] refer to Figure 5The inversion layer 120 also includes a fourth inversion layer 124, which is located on the front side 10 of the corresponding substrate 100 of the non-metallic region 12. The extension direction of the fourth inversion layer 124 is the same as that of the second inversion layer 122, and it is located between adjacent second inversion layers 122. The fourth inversion layer 124 is electrically connected to the first inversion layer 121 and also electrically connected to the third inversion layer 123.

[0065] In some embodiments, the width of the fourth inversion layer 124 along the extension direction Y of the first electrode 106 is less than or equal to the width of the second inversion layer 122 along the extension direction Y of the first electrode 106.

[0066] In some embodiments, the spacing between the second inversion layer 122 and the fourth inversion layer 124, or the spacing between two fourth inversion layers 124, can range from 200 μm to 1 cm. The spacing can be 203 μm, 420 μm, 560 μm, 710 μm, 860 μm, 1300 μm, or 6800 μm.

[0067] In some embodiments, continue to refer to Figure 2 When the orthographic projection of the passivated contact structure on the back side 20 overlaps with the orthographic projection of the inversion layer 120 on the back side 20, there is no lateral transport region for electrons and holes within the substrate 100, resulting in a shorter transport path and improved electron collection efficiency.

[0068] In some embodiments, reference Figure 6 The passivation contact structure's orthographic projection on the back side 20 partially overlaps with the inversion layer 120's orthographic projection on the back side 20, and the overlapping area is greater than or equal to 0.4 times the area of ​​the inversion layer 120. This overlapping area shortens the lateral transport path of charge carriers on the front side 10, allowing them to be collected quickly by the second electrode 116 on the back side 20. Furthermore, the staggered arrangement of the two electrodes allows for the processing of different regions of the substrate 100, avoiding safety issues caused by excessive mechanical manipulation leading to thinning of the substrate 100 in one area. The non-overlapping electrode collection areas also collect charge carriers from various electrode regions, thereby improving carrier collection efficiency. To illustrate the overlap between the passivation contact structure's orthographic projection on the back side 20 and the inversion layer 120's orthographic projection on the back side 20, a first staggered distance L is used as an illustration.

[0069] Continue to refer to Figure 2 The passivated contact structure includes a tunneling dielectric layer 131 and a doped conductive layer 132. The tunneling dielectric layer 131 is located on the back side 20 of the substrate 100, and the doped conductive layer 132 is located on the surface of the tunneling dielectric layer 131. The doped conductive layer 132 is doped with doping elements of the same conductivity type as the substrate 100.

[0070] In some embodiments, the doped conductive layer can form a band bend on the surface of the substrate 100, and the tunneling dielectric layer 131 causes an asymmetric shift in the energy band on the surface of the substrate 100, so that the potential barrier for the majority carriers is lower than the potential barrier for the minority carriers. Therefore, the majority carriers can more easily tunnel through the tunneling dielectric layer 131, while the minority carriers have difficulty passing through the tunneling dielectric layer 131, so as to achieve selective transport of carriers.

[0071] Furthermore, the tunneling dielectric layer 131 provides a chemical passivation effect. Specifically, due to interface state defects at the interface between the substrate 100 and the tunneling dielectric layer 131, the interface state density on the back surface 20 of the substrate 100 is relatively high. This increased interface state density promotes the recombination of photogenerated carriers, increasing the fill factor, short-circuit current, and open-circuit voltage of the solar cell, thereby improving the photoelectric conversion efficiency of the solar cell. By positioning the tunneling dielectric layer 131 on the back surface 20 of the substrate 100, the tunneling dielectric layer 131 provides a chemical passivation effect on the surface of the substrate 100. Specifically, by saturating the dangling bonds of the substrate 100, it reduces the defect state density of the substrate 100 and decreases the recombination centers of the substrate 100, thereby reducing the carrier recombination rate.

[0072] In some embodiments, the thickness of the tunneling dielectric layer 131 is 0.5 nm to 5 nm. The thickness range of the tunneling dielectric layer 131 is 0.5 nm to 1.3 nm, 1.3 nm to 2.6 nm, 2.6 nm to 4.1 nm, or 4.1 nm to 5 nm. When the thickness of the tunneling dielectric layer 131 is within any of these ranges, it is relatively thin, allowing majority carriers to easily tunnel through the tunneling dielectric layer 131, while minority carriers have difficulty passing through, thus achieving selective carrier transport.

[0073] In some embodiments, the doped conductive layer 132 serves as a field passivation effect. Specifically, an electrostatic field pointing inwards from the substrate 100 is formed on the surface of the substrate 100, causing minority carriers to escape from the interface, thereby reducing the minority carrier concentration and decreasing the carrier recombination rate at the interface of the substrate 100. This increases the open-circuit voltage, short-circuit current, and fill factor of the solar cell, thereby improving the photoelectric conversion efficiency of the solar cell.

[0074] In some embodiments, the substrate 100 is doped with N-type dopant, and the doped conductive layer 132 is doped with N-type dopant. The N-type dopant promotes uniform grain size and a single crystal structure in the doped conductive layer 132, and the doped conductive layer 132 with N-type dopant has a smaller particle size and a larger and more uniform number of grain boundaries.

[0075] In some embodiments, the back surface 20 of the non-metallic region 12 has a first textured surface structure and a second textured surface structure 114, wherein the roughness of the first textured surface structure is less than the roughness of the second textured surface structure 114. The second textured surface structure 114 includes a plurality of second protrusion structures 104, which can be a pyramid structure or a platform protrusion structure.

[0076] In some embodiments, the front surface 10 has a velvet structure 111, which includes a plurality of first protrusions 101. The first protrusions may be a pyramid structure or a platform protrusion structure.

[0077] In some embodiments, the front surface 10 of the metal region 11 has a third textured surface structure, and the front surface 10 of the non-metal region 12 has a fourth textured surface structure, wherein the roughness of the fourth textured surface structure is greater than or equal to the roughness of the third textured surface structure.

[0078] It should be noted that the first textured structure, the second textured structure, the third textured structure, the fourth textured structure, and any of the textured structures mentioned above can be used as light-trapping structures. The inclined surface of the light-trapping structure can increase the internal reflection of incident light, thereby improving the absorption and utilization rate of incident light by the substrate 100, and thus improving the cell efficiency of the solar cell.

[0079] In some embodiments, the distance between the surface of the substrate 100 containing the inversion layer 120 and the back surface 20 is a first distance, and the distance between the surface of the substrate 100 not containing the inversion layer 120 and the back surface 20 is a second distance, wherein the first distance is greater than the second distance.

[0080] In some embodiments, reference Figure 3 It also includes: a main electrode 107, the extension direction of the main electrode 107 intersects the extension direction of the first electrode 106, and the orthogonal projection of the main electrode 107 on the front side 10 is located in the second inversion layer 122.

[0081] In some embodiments, the solar cell further includes a first passivation layer 105, which covers the surface of the inversion layer 120 and the surface of the substrate 100 not covered by the inversion layer 120.

[0082] In some embodiments, the first passivation layer 105 may be a single-layer structure or a stacked structure, and the material of the first passivation layer 105 may be one or more of the following materials: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0083] In some embodiments, the solar cell further includes a second passivation layer 115, which covers the surface of the doped conductive layer 132 and the back surface 20 of the substrate 100. The second passivation layer 115 may be a single-layer structure or a stacked structure, and the material of the second passivation layer 115 may be one or more of the following materials: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0084] In some embodiments, the first electrode 106 may be formed by sintering a burn-through paste. A method for forming the first electrode 106 includes: printing a metal paste onto a portion of the surface of the first passivation layer 105 using a screen printing process. The metal paste may include at least one of silver, aluminum, copper, tin, gold, lead, or nickel. Then, the metal paste is subjected to a sintering process. The metal paste contains highly corrosive components such as glass powder, so that during sintering, the corrosive components will corrode the first passivation layer 105, thereby allowing the metal paste to penetrate into the first passivation layer 105 and make electrical contact with the first inversion layer 121.

[0085] In some embodiments, the first electrode 106 may be formed by sintering LECO (Laser-enhanced contact optimization) paste, and part of the LECO paste may etch the first passivation layer 105 and contact the first inversion layer 121 or form an electrical connection with the first inversion layer 121 through a crystal.

[0086] In some embodiments, the second electrode 116 may be formed by sintering a burn-through paste. A method for forming the second electrode 116 includes: printing a metal paste onto a portion of the surface of the second passivation layer 115 using a screen printing process. The metal paste may include at least one of silver, aluminum, copper, tin, gold, lead, or nickel. Then, the metal paste is subjected to a sintering process. The metal paste contains highly corrosive components such as glass powder, so that during sintering, the corrosive components will corrode the second passivation layer 115, thereby allowing the metal paste to penetrate into the second passivation layer 115 and make electrical contact with the doped conductive layer 132.

[0087] In some embodiments, the second electrode 116 may be sintered from LECO slurry, and part of the LECO slurry may be etched to form a second passivation layer 115 and contact the doped conductive layer 132 or form an electrical connection with the doped conductive layer 132 through a crystal.

[0088] The solar cell provided in the above embodiment has an inversion layer 120 disposed on the front side 10 of the solar cell. The inversion layer 120 is partially located in the metal region 11 and a portion of the non-metal region 12 of the solar cell. The first inversion layer 121 located in the metal region 11 can form a low-resistance heavily doped region, reducing metal recombination at the first electrode 106 and the contact resistance between the first electrode 106 and the first inversion layer 121. For the portion of the non-metal region 12, no inversion layer 120 is disposed, i.e., no heavily doped region is disposed, thereby reducing the carrier recombination rate in the non-metal region 12 of the front side 10.

[0089] In addition, a passivation contact structure is formed on the back side 20. The passivation contact structure is located on the metal region 11, which can ensure the passivation performance of the region where the metal region 11 is located and the heavy doping concentration of the region in contact with the second electrode 116.

[0090] Accordingly, according to some embodiments of this application, another aspect of this application also provides a method for preparing a solar cell, used to provide the solar cell described in the above embodiments. The same or corresponding technical features as those in the above embodiments will not be described in detail here. Figure 3 The method for fabricating a solar cell shown is an example.

[0091] refer to Figure 7 and Figure 8 The solar cell has a metallic region 11 and a non-metallic region 12. The fabrication method includes providing a substrate having a front side and a back side disposed opposite to each other. Specifically, an initial substrate 117 is provided. (Reference) Figure 9 One side of the initial substrate 117 is flocked to give one side of the initial substrate 117 a flocked structure 111. The flocked structure 111 includes a plurality of first protrusion structures 101.

[0092] In some embodiments, the texturing process includes chemical etching, for example, cleaning the initial substrate 117 with a mixed solution of potassium hydroxide and hydrogen peroxide. Specifically, the desired texturing structure can be formed by controlling the concentration ratio of potassium hydroxide and hydrogen peroxide solutions. In some embodiments, the texturing structure can also be formed using methods such as laser etching, mechanical etching, or plasma etching. In laser etching, the desired texturing structure is obtained by controlling the laser process parameters.

[0093] refer to Figure 10 as well as Figure 11 A reverse layer 120 is formed, which is located on the surface of the substrate 100. The reverse layer 120 includes a first reverse layer 121, which is located on the front side of the substrate 100 corresponding to the metal region 11.

[0094] In some embodiments, the inversion layer further includes a second inversion layer 122, which is located on the front side of the corresponding substrate 100 of the partial non-metallic region 12 and connects two adjacent first inversion layers 121.

[0095] In some embodiments, reference Figure 7 The front side 10 includes a first processed region 21 and a first unprocessed region 22. The method for preparing the inversion layer 120 includes: (refer to...) Figure 10 The front side 10 of the initial substrate 117 is doped to convert a portion of the initial substrate 117 into a doped layer; Reference Figure 11 The doped layer in the first processing region is removed, and the doped layer in the first non-processing region is retained as the inversion layer 120. The inversion layer 120 in the metal region 11 is the first inversion layer 121, and the part of the inversion layer 120 in the non-metal region 12 is the second metal layer.

[0096] In some embodiments, the front side 10 includes a second processed region and a second unprocessed region, and the method for forming the inversion layer 120 includes: performing laser doping on the second processed region of the substrate 100 to convert a portion of the substrate 100 into the inversion layer 120.

[0097] In some embodiments, the parameters for laser doping treatment include: laser frequency 400KHz-1200KHz; laser spot size 60μm-200μm; laser energy 1W-20W; laser scanning speed 3000m / s-50000m / s; and laser overlap rate 50%-90%.

[0098] refer to Figures 12-14 This forms a passivated contact structure, which is located on the back side 20 of the metal region 11.

[0099] In some embodiments, reference Figure 12 A dielectric film 102 is formed on the back side; a doped conductive film 103 is formed on the surface of the dielectric film 102; reference. Figure 13 After removing the dielectric film and doped conductive film in non-metallic region 12, the remaining dielectric film serves as the tunneling dielectric layer, and the remaining doped conductive film serves as the doped conductive layer; Reference Figure 14 The initial substrate 117 of the non-metallic region 12 is etched to form a second textured surface structure on the surface of the initial substrate 117 of the non-metallic region 12, and the remaining initial substrate 117 serves as substrate 100.

[0100] In some embodiments, the dielectric film and the doped conductive film of the non-metallic region 12 can be removed in one step, and a second textured structure can be formed on the surface of the initial substrate 117 of the non-metallic region 12.

[0101] refer to Figure 15 A first passivation layer 105 and a second passivation layer 115 are formed. The first passivation layer 105 covers the surface of the inversion layer 120 and the surface of the substrate 100 not covered by the inversion layer 120. The second passivation layer 115 covers the surface of the doped conductive layer 132 and the back side of the substrate 100.

[0102] refer to Figure 2 A first electrode 106 is formed, which is located on the substrate 100 corresponding to the metal region 11 and is electrically connected to the first inversion layer 121; a second electrode 116 is formed, which is located on the passivation contact structure corresponding to the metal region 11 and is electrically connected to the passivation contact structure.

[0103] Accordingly, based on some embodiments of this application, reference is made to Figure 16 In another aspect, this application provides a tandem battery, comprising: a bottom battery, which is a solar cell as described in any of the above embodiments or a solar cell prepared by any of the above embodiments; and a top battery, which is located on the side of the substrate of the bottom battery away from the electrodes. Figure 18 This is a cross-sectional structural diagram of a stacked battery provided in another embodiment of this application.

[0104] In some embodiments, the stacked battery has a first grid line 186 of a first polarity and a second grid line of a second polarity. The first grid line 186 is in electrical contact with the top battery 180, and the second grid line is in electrical contact with the bottom battery 150. The second grid line is the first electrode 106 of the bottom battery.

[0105] In some embodiments, an interface layer 181 is provided between the top battery and the bottom battery, and the interface layer 181 also covers a passivated contact structure.

[0106] It is worth noting that the stacked battery in this application embodiment only illustrates two layers of solar cells. Those skilled in the art can set up three layers of solar cells or more than three layers of multi-layer stacked solar cells according to actual needs.

[0107] In some embodiments, the top cell 180 can be a perovskite solar cell, which includes: a first transport layer 182, a perovskite substrate 183, a second transport layer 184, a transparent conductive layer 185, and an antireflection layer (not shown). The first transport layer is directly opposite the bottom cell.

[0108] In some embodiments, the first transport layer may be either an electron transport layer or a hole transport layer, and the second transport layer may be either an electron transport layer or a hole transport layer.

[0109] Accordingly, according to some embodiments of this application, another aspect of this application provides a photovoltaic module, including the solar cell provided in the above embodiments, with the same or corresponding technical features as the above embodiments, which will not be described in detail here.

[0110] refer to Figure 17 and Figure 18 A photovoltaic module includes: a battery string, which is formed by electrically connecting multiple solar cells as described in any of the above embodiments, solar cells prepared by any of the above embodiments, or tandem cells as described in the above embodiments; a connecting component 218 for electrically connecting two adjacent solar cells 20; an encapsulating film 21 for covering the surface of the battery string; and a cover plate 22 for covering the surface of the encapsulating film 21 facing away from the battery string.

[0111] Specifically, in some embodiments, multiple solar cells can be electrically connected to each other via a connecting member 218, which is welded to the main grid on the solar cell. The main grid includes a main electrode 107 electrically connected to a first electrode 106 and a main electrode electrically connected to a second electrode 116.

[0112] In some embodiments, there is no spacing between the solar cells, meaning that the solar cells overlap each other.

[0113] In some embodiments, the connecting member 218 is welded to a sub-gate 208 on the battery cell, the sub-gate 208 including a first electrode 106 and a second electrode 116.

[0114] In some embodiments, the encapsulating film 21 includes a first encapsulating layer and a second encapsulating layer. The first encapsulating layer covers one of the front or back sides of the solar cell, and the second encapsulating layer covers the other of the front or back sides of the solar cell. Specifically, at least one of the first encapsulating layer or the second encapsulating layer can be an organic encapsulating film such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate copolymer (EVA) film, polyvinyl octene coelastomer (POE) film, or polyethylene terephthalate (PET) film.

[0115] It is worth noting that the first encapsulation layer and the second encapsulation layer still have a dividing line before lamination. After lamination, the photovoltaic module will no longer have the concept of a first encapsulation layer and a second encapsulation layer. That is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film 21.

[0116] In some embodiments, the cover plate 22 can be a glass cover plate, a plastic cover plate, or other cover plate with light-transmitting function. Specifically, the surface of the cover plate 22 facing the encapsulating film 21 can be an uneven surface, thereby increasing the utilization rate of incident light. The cover plate 22 includes a first cover plate and a second cover plate, the first cover plate being opposite to the first encapsulation layer and the second cover plate being opposite to the second encapsulation layer; or the first cover plate being opposite to one side of the solar cell and the second cover plate being opposite to the other side of the solar cell.

[0117] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of this application. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A solar cell, characterized in that, The solar cell has metallic regions and non-metallic regions, including: A substrate having a front side and a back side disposed opposite to each other; A reflection layer is located on the surface of the substrate; the reflection layer includes a first reflection layer located on the front side corresponding to the metal region; the distance between the surface of the substrate containing the reflection layer and the back side is a first distance, and the distance between the surface of the substrate not containing the reflection layer and the back side is a second distance, wherein the first distance is greater than the second distance; The first electrode is located on the substrate corresponding to the metal region and is electrically connected to the first inversion layer. A passivated contact structure is located on the back side of the metal region; The second electrode is located on the passivated contact structure corresponding to the metal region and is electrically connected to the passivated contact structure; Wherein, the orthographic projection of the passivation contact structure on the back side overlaps with the orthographic projection of the inversion layer on the back side; or, the orthographic projection of the passivation contact structure on the back side partially overlaps with the orthographic projection of the inversion layer on the back side, and the overlapping area is greater than or equal to 0.4 times the area of ​​the inversion layer.

2. The solar cell according to claim 1, characterized in that, The inversion layer includes a second inversion layer located on the corresponding front side of a portion of the non-metallic region and connecting two adjacent first inversion layers.

3. The solar cell according to claim 2, characterized in that, The inversion layer further includes a third inversion layer, which is located on the front side corresponding to the non-metallic region. The extension direction of the third inversion layer is the same as that of the first inversion layer, and it is located between adjacent first inversion layers. The third inversion layer is electrically connected to the second inversion layer.

4. The solar cell according to claim 3, characterized in that, Along the arrangement direction of the first electrode, the ratio of the total width of the orthographic projection of the first inversion layer and the third inversion layer on the front surface to the width of the front surface ranges from 3% to 40%, and / or, along the extension direction of the first electrode, the ratio of the total width of the orthographic projection of the second inversion layer on the front surface to the length of the front surface ranges from 2% to 20%.

5. A method for preparing a solar cell, characterized in that, The solar cell has metallic regions and non-metallic regions, including: A substrate is provided, the substrate having a front side and a back side disposed opposite to each other; An inversion layer is formed, the inversion layer being located on the surface of the substrate; the inversion layer includes a first inversion layer, the first inversion layer being located on the front side corresponding to the metal region; the distance between the surface of the substrate containing the inversion layer and the back side is a first distance, and the distance between the surface of the substrate not containing the inversion layer and the back side is a second distance, the first distance being greater than the second distance; A first electrode is formed, which is located on the substrate corresponding to the metal region and is electrically connected to the first inversion layer; A passivated contact structure is formed, the passivated contact structure being located on the back side of the metal region; wherein, the orthographic projection of the passivated contact structure on the back side overlaps with the orthographic projection of the inversion layer on the back side; or, the orthographic projection of the passivated contact structure on the back side partially overlaps with the orthographic projection of the inversion layer on the back side, and the overlapping area is greater than or equal to 0.4 times the area of ​​the inversion layer. A second electrode is formed, which is located on the passivation contact structure corresponding to the metal region and is electrically connected to the passivation contact structure.

6. The method for preparing a solar cell according to claim 5, characterized in that, The inversion layer further includes a second inversion layer, and the front side includes a first processed region and a first unprocessed region. The method for forming the inversion layer includes: The front side of the substrate is doped to convert a portion of the substrate thickness into a doped layer. Remove the doped layer in the first processing region and retain the doped layer in the first non-processing region as an inversion layer, wherein the inversion layer in the metal region is a first inversion layer and the portion of the inversion layer in the non-metal region is a second inversion layer.

7. The method for preparing a solar cell according to claim 5, characterized in that, The front side includes a second processed region and a second unprocessed region, and the method for preparing the inversion layer includes: The second processing region of the substrate is subjected to laser doping treatment to convert a portion of the substrate into an inversion layer.

8. A photovoltaic module, characterized in that, include: A battery string is formed by connecting multiple solar cells as described in any one of claims 1 to 4 or solar cells prepared by the preparation method as described in any one of claims 5 to 7; A connecting component for electrically connecting two adjacent solar cells; 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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