Solar cell, preparation method thereof and photovoltaic module

Abstract

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

Description

Technical Field

[0001] The embodiments of the present application relate to the photovoltaic field, and in particular to a solar cell and a method for preparing the same, and a photovoltaic module. Background Art

[0002] At present, with the gradual depletion of fossil energy, solar cells are becoming more and more widely used as a new energy alternative. Solar cells are devices that convert sunlight into electrical energy. Solar cells use the photovoltaic principle to generate carriers, and then use electrodes to lead the carriers out, thereby facilitating the effective use of electrical energy.

[0003] The current solar cells mainly include IBC cells (Interdigitated Back Contact), TOPCON (Tunnel Oxide Passivated Contact), PERC cells (Passivated emitter and real cell) and heterojunction cells, etc. The photoelectric conversion efficiency of solar cells is improved by reducing optical losses and reducing the recombination of photogenerated carriers on the surface and in the body of the silicon substrate through different film layer settings and functional limitations.

[0004] However, the cell efficiency of current solar cells is still poor. Summary of the invention

[0005] The embodiments of the present application provide a solar cell and a method for preparing the same, and a photovoltaic module, which are at least beneficial to improving the cell efficiency of the solar cell.

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

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

[0008] In some embodiments, the inversion layer also includes a third inversion layer, the third inversion layer is located on the corresponding front side of the non-metallic area, the extension direction of the third inversion layer is the same as the extension direction of the first inversion layer, and the third inversion layer is located between adjacent first inversion layers, and 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 is in the range of 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 is in the range of 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 including the inversion layer and the back side is a first distance, and the distance between the surface of the substrate not including the inversion layer and the back side is a second distance, and the first distance is greater than the second distance.

[0012] According to some embodiments of the present application, on the other hand, the embodiments of the present application further provide a method for preparing a solar cell, wherein the solar cell has a metal region and a non-metal region, comprising: providing a substrate, wherein the substrate has a front side and a back side relatively arranged; forming an inversion layer, wherein the inversion layer is located on the front side of the substrate; the inversion layer comprises a first inversion layer, wherein the first inversion layer is located on the front side corresponding to the metal region; forming a first electrode, wherein the first electrode is located on the substrate corresponding to the metal region and is electrically connected to the first inversion layer; forming a passivation contact structure, wherein the passivation contact structure is located on the back side of the metal region; forming a second electrode, wherein the second electrode is located on the passivation contact structure corresponding to the metal region and is electrically connected to the passivation contact structure.

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

[0014] In some embodiments, the front side includes a second processed area and a second non-processed area, and the preparation method for forming the inversion layer includes: performing laser doping treatment on the second processed area of ​​the substrate to convert a partial area of ​​the substrate into an inversion layer.

[0015] According to some embodiments of the present application, another aspect of the embodiments of the present application further provides a photovoltaic assembly, including: a cell string, formed by connecting a plurality of solar cells as described in any one of the above embodiments or a solar cell prepared by the preparation method as described in any one of the above embodiments; a connecting component, wherein the connecting component is used to electrically connect two adjacent solar cells; a packaging film, used to cover the surface of the cell string; and a cover plate, used to cover the surface of the packaging film facing away from the cell string.

[0016] The technical solution provided by the embodiment of the present application has at least the following advantages:

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

[0018] In addition, a passivation contact structure is formed on the back side, and the passivation contact structure is located on the metal area, which can ensure the passivation performance of the area where the metal area is located and the heavy doping concentration of the area contacted by the second electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] One or more embodiments are exemplarily illustrated by the figures in the corresponding drawings. These exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise specified, the figures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present application or the technical solutions in the traditional technology, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A schematic diagram of the structure of a solar cell provided in one embodiment of the present application;

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

[0022] Figure 3A schematic diagram of the structure of another solar cell provided in one embodiment of the present application;

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

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

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

[0026] Figure 7 to Figure 15 A schematic diagram of the structure of a solar cell corresponding to each step in a method for preparing a solar cell provided in another embodiment of the present application;

[0027] Fig.16 A schematic structural diagram of a laminated battery provided in yet another embodiment of the present application;

[0028] Fig.17 A schematic diagram of the structure of a photovoltaic module provided in one embodiment of the present application;

[0029] Fig.18 for Fig.17 Schematic diagram of the cross-sectional structure along the M1-M2 section. DETAILED DESCRIPTION

[0030] As known from the background art, the cell efficiency of current solar cells is poor.

[0031] The embodiments of the present application provide a solar cell and a method for preparing the same, and a photovoltaic module. By providing an inversion layer, and the inversion layer being located in a metal region, the optical loss in a non-metal region is reduced and the contact performance between an electrode and the inversion layer is improved, thereby improving the cell efficiency.

[0032] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0033] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0034] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0035] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0036] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0037] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0038] In the drawings corresponding to the embodiments of the present application, the thickness and area of ​​the layers are exaggerated for better understanding and ease of description. When describing a component (such as a layer, film, region or substrate) on another component or on the surface of another component, the component may be "directly" located on the surface of the other component, or a third component may be present between the two components. On the contrary, when describing a component on the surface of another component or when another component is formed or provided on the surface of a component, it means that there is no third component between the two components. In addition, when describing a component as being "substantially" 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 partial edge of the entire surface.

[0039] In the description of the embodiments of the present application, when a component "includes" another component, unless otherwise specified, other components are not excluded, and other components may be further included. In addition, when a component such as a layer, film, region, or plate is referred to as being "on / located on" another component, it may 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 exist in between. In addition, 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 means that no other components are located in between.

[0040] The terms used in the description of the various embodiments described herein are only used to describe specific embodiments and are not intended to be limiting. As used in the description of the various embodiments described and in the appended claims, "the part" is also intended to include the plural form unless the context clearly indicates otherwise. Among them, a component includes a layer, a film, a region, or a plate.

[0041] The following will describe the various embodiments of the present application in detail with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that in the various embodiments of the present application, many technical details are provided in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solution claimed in the present application can be implemented.

[0042] Figure 1 A schematic diagram of the structure of a solar cell provided in one embodiment of the present application; Figure 2 for Figure 1 A cross-sectional view along the A1-A2 section.

[0043] refer to Figure 1 and Figure 2According to some embodiments of the present application, on the one hand, the embodiments of the present application provide a solar cell, the solar cell having a metal area 11 and a non-metal area 12, the solar cell comprising: a substrate 100, the substrate 100 having a front side 10 and a back side 20 arranged opposite to each other; an inversion layer 120, the inversion layer 120 is located on the front side 10 of the substrate 100; the inversion layer comprises a first inversion layer 121, the first inversion layer 121 is located on the front side 10 of the substrate 100 corresponding to the metal area 11; a first electrode 106, the first electrode 106 is located on the substrate 100 corresponding to the metal area 11, and is electrically connected to the first inversion layer 121; a passivation contact structure, the passivation contact structure is located on the back side 20 of the metal area 11; a second electrode 116, the second electrode 116 is located on the passivation contact structure corresponding to the metal area 11, and is electrically connected to the passivation contact structure. In this way, an inversion layer 120 is set on the front side 10 of the solar cell, and the inversion layer 120 is locally located in the metal area 11 and part of the non-metal area 12 of the solar cell. The first inversion layer 121 located in the metal area 11 can form a low-resistance heavily doped area, thereby 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 set for part of the non-metal area 12, that is, the heavily doped area is not set, thereby reducing the carrier recombination rate of the non-metal area 12 of the front side 10.

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

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

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

[0047] In some embodiments, the substrate 100 may be an N-type semiconductor substrate 100 or a P-type semiconductor substrate 100. The N-type semiconductor substrate 100 is doped with an N-type doping element, and the N-type doping element may be any one of the V-group elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type semiconductor substrate 100 is doped with a P-type element, and the P-type doping element may be any one of the III-group 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 that are arranged opposite to each other. The solar cell is a single-sided cell, the front side 10 can be used as a light-receiving side for receiving incident light, and the back side 20 is used as a backlight side. Among them, the backlight side can also receive incident light, but the efficiency of receiving the incident light is weaker than that of the light-receiving side.

[0049] In some embodiments, the metal region 11 refers to the region where the orthographic projection of the first electrode 106 on the substrate 100 is located, and the non-metal region 12 refers to the region other than the orthographic projection of the first electrode 106 on the substrate 100. In order to ensure that the film layer contacted by the first electrode 106 has a large doping concentration or the region 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 orthographic projection of the first electrode 106 on 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 the other of the N-type doping element and the P-type doping element.

[0051] In some embodiments, reference Figure 1 , the width of the first inversion layer 121 along the arrangement direction of the first inversion layer 121 ranges from 20 μm to 500 μm. The width range of the first inversion layer 121 can make the area directly facing the first electrode 106 all be the first inversion layer 121, and the area formed as the PN junction, that is, the area where electrons or holes are formed, is larger, thereby having a greater battery efficiency. This width range can also make the recombination centers formed by the high doping concentration on the surface of the substrate 100 less, so that the recombination carrier rate on the surface of the substrate 100 is lower.

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

[0053] refer to Figure 3, the 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 area 12, and connects two adjacent first inversion layers 121. For the second inversion layer 122 located in the non-metallic area 12, the two adjacent first inversion layers 121 are connected, thereby realizing electrical transmission between the two first inversion layers 121, and reducing the lateral transmission resistance. Secondly, after the second inversion layer 122 is set, the ability of lateral transmission between electrodes is realized. Under the premise of ensuring a strong lateral transmission ability, 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, thereby reducing the shielding area.

[0054] In some embodiments, the inversion layer 120 located in the metal region 11 can be used as an emitter, and the inversion layer 120 located in the non-metal region 12 can be used as a transmission layer, which can improve the lateral transmission capacity between adjacent emitters, thereby improving the battery efficiency. Among them, the first inversion layer 121 located in the metal region 11 is used as an emitter, and the second inversion layer 122 located in the non-metal region 12 is used as a transmission layer.

[0055] In some embodiments, reference Figure 4 The inversion layer 120 further includes a third inversion layer 120, the third inversion layer 123 is located on the front surface 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 the extension direction of the first inversion layer 121, and is located between adjacent first inversion layers 121, and the third inversion layer 123 is electrically connected to the second inversion layer 122. The third inversion layer 123 acts as an emitter to increase the area for electron and hole conversion, thereby improving the battery efficiency.

[0056] In some embodiments, the number of the third inversion layers 123 between adjacent first inversion layers 121 is 0 to 10. The number of the third inversion layers 123 can increase the area of ​​the electron and hole conversion region, and 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 the third inversion layers 123 between adjacent first inversion layers 121 may 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, the width of the first inversion layer 121 along the arrangement direction of the first inversion layer 121 is a second width, and the first width is less than or equal to the second width. In this way, the third inversion layer 123 can be set smaller, which can shorten the area of ​​the two adjacent regions transmitted to the third inversion layer 123 and avoid the problem of a larger recombination rate on the surface of the substrate 100 caused by more 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 the third inversion layer 123 and the third inversion layer 123 may range from 100 μm to 1000 μm. The spacing may 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 on the front surface 10 to the width of the front surface 10 is in the range of 3% to 40%. In this way, the area of ​​the inversion layer 120 can be ensured to be larger, and the larger area can be used as the conversion area of ​​the photogenerated carriers, thereby obtaining a larger open circuit voltage and battery efficiency, and the series resistance between the first electrode 106 and the inversion layer 120 is lower, and the electrical loss of the battery is less.

[0061] In some embodiments, the ratio of the total width of the orthographic projections of the first inversion layer 121 and the third inversion layer 123 on the front surface 10 to the width of the front surface 10 may 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 may be 53 μm, 88 μm, 120 μm, 210 μm, 380 μm, 500 μm or 600 μm.

[0063] In some embodiments, along the extension direction of the first electrode 106, the ratio of the total width of the orthographic projection of the second inversion layer 122 on the front surface 10 to the length of the front surface 10 is in the range of 2% to 20%. The ratio of the total width of the orthographic projection of the second inversion layer 122 on the front surface 10 to the length of the front surface 10 may 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 substrate 100 corresponding to the non-metallic area 12. The extension direction of the fourth inversion layer 124 is the same as the extension direction of the second inversion layer 122, and is located between adjacent second inversion layers 122. The fourth inversion layer 124 is electrically connected to the first inversion layer 121, and the fourth inversion layer 124 is 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 the fourth inversion layer 124 and the fourth inversion layer 124 may range from 200 μm to 1 cm. The spacing may 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 The positive projection of the passivation contact structure on the back side 20 overlaps with the positive projection of the inversion layer 120 on the back side 20, so there is no lateral transmission area for electrons and holes in the substrate 100, so the transmission path is shorter, thereby improving the efficiency of electron collection.

[0068] In some embodiments, reference Figure 6 , the orthographic projection of the passivation contact structure on the back side 20 partially overlaps with the orthographic projection of the inversion layer 120 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. In this way, the overlapping area range makes the lateral transmission path of the carriers located on the front side 10 shorter, so that the carriers can be collected by the second electrode 116 located on the back side 20 as soon as possible. Secondly, the two are staggered from each other, so that different areas of the substrate 100 can be processed, avoiding the safety problem caused by the thinning of the thickness of the substrate 100 due to too many mechanical operations, and the non-overlapping electrode collection area between the two can also collect carriers in various areas of the electrode, thereby improving the carrier collection efficiency. Among them, in order to illustrate that the orthographic projection of the passivation contact structure on the back side 20 partially overlaps with the orthographic projection of the inversion layer 120 on the back side 20, the first distance L between the two is staggered as an illustration.

[0069] Continue to refer Figure 2 The passivation 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 an energy band bending on the surface of the substrate 100, and the tunneling dielectric layer 131 causes the energy band on the surface of the substrate 100 to shift asymmetrically, so that the potential barrier to the majority carriers (also called majority carriers) among the carriers is lower than the potential barrier to the minority carriers (also called minority carriers) among the carriers. Therefore, the majority carriers can more easily perform quantum tunneling through the tunneling dielectric layer 131, while the minority carriers find it difficult to pass through the tunneling dielectric layer 131, so as to realize the selective transmission of carriers.

[0071] In addition, the tunnel dielectric layer 131 has a chemical passivation effect. Specifically, due to the presence of interface state defects at the interface between the substrate 100 and the tunnel dielectric layer 131, the interface state density of the back side 20 of the substrate 100 is relatively large. The increase in the interface state density promotes the recombination of photogenerated carriers, increases the fill factor, short-circuit current and open-circuit voltage of the solar cell, and improves the photoelectric conversion efficiency of the solar cell. The tunnel dielectric layer 131 is arranged on the back side 20 of the substrate 100, so that the tunnel dielectric layer 131 has a chemical passivation effect on the surface of the substrate 100, specifically: by saturating the dangling bonds of the substrate 100, reducing the defect state density of the substrate 100, and reducing the recombination center of the substrate 100 to reduce 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 of the tunneling dielectric layer 131 ranges from 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 the above ranges, the thickness of the tunneling dielectric layer 131 is thinner, and majority carriers can easily perform quantum tunneling through the tunneling dielectric layer 131, while minority carriers have difficulty passing through the tunneling dielectric layer 131, so as to achieve selective transmission of carriers.

[0073] In some embodiments, the doped conductive layer 132 has a field passivation effect. Specifically, an electrostatic field pointing to the inside of the substrate 100 is formed on the surface of the substrate 100, so that minority carriers escape from the interface, thereby reducing the minority carrier concentration, so that the carrier recombination rate at the interface of the substrate 100 is reduced, thereby increasing the open circuit voltage, short circuit current and fill factor of the solar cell, and improving the photoelectric conversion efficiency of the solar cell.

[0074] In some embodiments, the doping element type of the substrate 100 is N-type, and the doped conductive layer 132 is doped with N-type doping elements. The N-type doping elements cause the grains of the doped conductive layer 132 to be uniform and have a single crystal structure, and the grain size of the doped conductive layer 132 having the N-type doping elements is smaller, and the number of grain boundaries is larger and more uniform.

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

[0076] In some embodiments, the front surface 10 has a suede structure 111, and the suede structure 111 includes a plurality of first protrusion structures 101. The first protrusion structure 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 velvet structure, and the front surface 10 of the non-metal region 12 has a fourth velvet structure, and the roughness of the fourth velvet structure is greater than or equal to the roughness of the third velvet structure.

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

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

[0080] In some embodiments, reference Figure 3 , further comprising: a main electrode 107 , the extension direction of the main electrode 107 intersects with the extension direction of the first electrode 106 , and the orthographic 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 , wherein the first passivation layer 105 covers a surface of the inversion layer 120 and a 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-layer structure, and the material of the first passivation layer 105 may be one or more of silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride oxide, titanium oxide, hafnium oxide or aluminum oxide.

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

[0084] In some embodiments, the first electrode 106 may be formed by sintering a burn-through paste. The method for forming the first electrode 106 includes: printing a metal paste on 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, and the metal paste contains a material with a highly corrosive component such as glass powder. In this way, during the sintering process, the corrosive component will corrode the first passivation layer 105, so that the metal paste penetrates into the first passivation layer 105 and is in electrical contact with the first inversion layer 121.

[0085] In some embodiments, the first electrode 106 may be sintered from LECO (Laser-enhanced contact optimization) slurry, and part of the LECO slurry corrodes the first passivation layer 105 and contacts the first inversion layer 121 or forms an electrical connection with the first inversion layer 121 through crystals.

[0086] In some embodiments, the second electrode 116 can be formed by sintering a burn-through paste. The method for forming the second electrode 116 includes: printing a metal paste on a portion of the second passivation layer 115 surface 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, and the metal paste contains a material with a highly corrosive component such as glass powder. In this way, during the sintering process, the corrosive component will corrode the second passivation layer 115, so that the metal paste penetrates into the second passivation layer 115 and is in electrical contact with the doped conductive layer 132.

[0087] In some embodiments, the second electrode 116 may be formed by sintering LECO slurry, and a portion of the LECO slurry corrodes the second passivation layer 115 and contacts the doped conductive layer 132 or forms an electrical connection with the doped conductive layer 132 through crystals.

[0088] In the solar cell provided in the above embodiment, 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 area 11 and part of the non-metal area 12 of the solar cell. The first inversion layer 121 located in the metal area 11 can form a low-resistance heavily doped area, thereby 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 for the part of the non-metal area 12, that is, the heavily doped area is not provided, thereby reducing the carrier recombination rate of the non-metal area 12 of the front side 10.

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

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

[0091] refer to Figure 7 and Figure 8 The solar cell has a metal region 11 and a non-metal region 12. The preparation method includes: providing a substrate 100, wherein the substrate 100 has a front side 10 and a back side 20 which are arranged opposite to each other.

[0092] refer to Fig. 9 , a texturing process is performed on one side of the initial substrate 107 so that one side of the initial substrate 107 has a suede structure 111 . The suede structure 111 includes a plurality of first protruding structures 101 .

[0093] In some embodiments, the texturing process includes: chemical etching, for example, a mixed solution of potassium hydroxide and hydrogen peroxide solution can be used to clean the initial substrate 107, and the suede structure with the expected morphology can be formed by controlling the concentration ratio of potassium hydroxide and hydrogen peroxide solution. In some embodiments, the suede structure can also be formed by laser etching, mechanical method or plasma etching. In laser etching, the suede structure with the expected morphology is obtained by controlling the laser process parameters.

[0094] refer to Fig.10 as well as Fig.11 , forming an inversion layer 120 , the inversion layer 120 is located on the surface of the substrate 100 ; the inversion layer 120 includes a first inversion layer 121 , and the first inversion layer 121 is located on the front side 10 of the substrate 100 corresponding to the metal area 11 .

[0095] In some embodiments, the inversion layer further includes a second inversion layer 122 . The second inversion layer 122 is located on the front surface 10 of the substrate 100 corresponding to the portion of the non-metallic region 12 and connects two adjacent first inversion layers 121 .

[0096] In some embodiments, reference Figure 7 The front surface 10 includes a first treated area 21 and a first non-treated area 22. The preparation method for forming the inversion layer 120 includes: referring to Fig.10 , doping is performed on the front surface 10 of the substrate 100 so that a portion of the thickness of the substrate 100 is converted into a doped layer; Fig.11 , remove the doped layer in the first treated area, and retain the doped layer in the first non-treated area as the inversion layer 120, wherein the inversion layer 120 in the metal area 11 is used as the first inversion layer 121, and the part of the inversion layer 120 in the non-metal area 12 is used as the second metal layer.

[0097] In some embodiments, the front side 10 includes a second processed area and a second unprocessed area, and the preparation method for forming the inversion layer 120 includes: performing laser doping treatment on the second processed area of ​​the substrate 100 to convert a partial area of ​​the substrate 100 into the inversion layer 120 .

[0098] In some embodiments, the parameters of the laser doping process include: laser frequency 400KHz-1200KHz; laser spot size 60μm-200μm; laser energy 1W-20W; laser scanning speed 3000m / s-50000m / s; laser overlap rate 50%-90%.

[0099] refer to Figure 12 to Figure 14 , forming a passivation contact structure, and the passivation contact structure is located on the back side 20 of the metal region 11.

[0100] In some embodiments, reference Fig.12 , forming a dielectric film 102, the dielectric film 102 is located on the back side 20; forming a doped conductive film 103, the doped conductive film 103 is located on the surface of the dielectric film 102; referring to Fig.13 , remove the dielectric film and the doped conductive film of the non-metallic region 12, the remaining dielectric film is used as a tunneling dielectric layer, and the remaining doped conductive film is used as a doped conductive layer; refer to Fig.14 , the initial substrate 100 of the non-metallic area 12 is etched so that a second velvet structure is formed on the surface of the initial substrate 100 of the non-metallic area 12 , and the remaining initial substrate 100 serves as the substrate 100 .

[0101] In some embodiments, the dielectric film and the doped conductive film of the non-metallic region 12 can be removed in one step, and the surface of the initial substrate 100 of the non-metallic region 12 can be formed into a second textured structure.

[0102] refer to Fig.15 , forming a first passivation layer 105 and a second passivation layer 115, 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, the second passivation layer 115 covers the surface of the doped conductive layer 132 and the back side 20 of the substrate 100.

[0103] refer to Figure 2 , forming a first electrode 106, the first electrode 106 is located on the substrate 100 corresponding to the metal area 11, and is electrically connected to the first inversion layer 121; forming a second electrode 116, the second electrode 116 is located on the passivation contact structure corresponding to the metal area 11, and is electrically connected to the passivation contact structure.

[0104] Accordingly, according to some embodiments of the present application, reference Fig.16 On the other hand, the embodiments of the present application further provide a stacked battery, including: a bottom battery, which is a solar cell as in any one of the above embodiments or a solar cell prepared by the preparation method as in any one of the above embodiments; and a top battery, which is located on the side of the substrate in the bottom battery away from the electrode. Fig.18 A schematic cross-sectional structure diagram of a stacked battery provided in yet another embodiment of the present application.

[0105] In some embodiments, the stacked battery has a first gridline 186 of a first polarity and a second gridline of a second polarity, wherein the first gridline 186 is in electrical contact with the top battery 180 and the second gridline is in electrical contact with the bottom battery 150. The second gridline is the first electrode 106 of the bottom battery.

[0106] In some embodiments, there is an interface layer 181 between the top cell and the bottom cell, and the interface layer 181 also covers the passivation contact structure.

[0107] It is worth noting that the stacked cell in the embodiment of the present application only illustrates two layers of solar cells, and those skilled in the art can set three layers of solar cells or more than three layers of stacked solar cells according to actual needs.

[0108] In some embodiments, the top cell 180 may be a perovskite solar cell, which includes: a stacked first transmission layer 182, a perovskite substrate 183, a second transmission layer 184, a transparent conductive layer 185, and an anti-reflection layer (not shown), wherein the first transmission layer is opposite to the bottom cell.

[0109] In some embodiments, the first transport layer may be one of an electron transport layer and a hole transport layer, and the second transport layer may be the other of the electron transport layer and the hole transport layer.

[0110] Accordingly, according to some embodiments of the present application, the embodiments of the present application further provide a photovoltaic module, including the solar cell provided in the above embodiments, and the technical features that are the same as or corresponding to the above embodiments are not described in detail here.

[0111] refer to Fig.17 and Fig.18 , a photovoltaic module includes: a battery string, which is electrically connected by a plurality of solar cells as in any of the above embodiments, a solar cell prepared by the preparation method as in any of the above embodiments, or a laminated battery as described in the above embodiments; a connecting component 218, the connecting component 218 is used to electrically connect two adjacent solar cells 20; a packaging film 21, which is used to cover the surface of the battery string; a cover plate 22, which is used to cover the surface of the packaging film 21 away from the battery string.

[0112] Specifically, in some embodiments, multiple cells can be electrically connected through a connecting member 218, and the connecting member 218 is welded to a main grid on the cell. The main grid includes a main electrode 107 electrically connected to the first electrode 106 and a main electrode electrically connected to the second electrode 116.

[0113] In some embodiments, no intervals are set between the battery cells, that is, the battery cells overlap each other.

[0114] In some embodiments, the connection component 218 is welded to the secondary grid 208 on the solar cell, and the secondary grid 208 includes the first electrode 106 and the second electrode 116 .

[0115] In some embodiments, the encapsulation film 21 includes a first encapsulation layer and a second encapsulation layer, the first encapsulation layer covers one of the front side or the back side of the solar cell, and the second encapsulation layer covers the other of the front side or the back side of the solar cell. Specifically, at least one of the first encapsulation layer or the second encapsulation layer can be an organic encapsulation film such as a polyvinyl butyral (PVB) film, an ethylene-vinyl acetate copolymer (EVA) film, a polyethylene octene co-elastomer (POE) film or a polyethylene terephthalate (PET) film.

[0116] It is worth noting that there is a boundary line between the first encapsulation layer and the second encapsulation layer before lamination. After lamination, the photovoltaic module is no longer 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.

[0117] In some embodiments, the cover plate 22 may be a glass cover plate, a plastic cover plate or the like with a light-transmitting function. Specifically, the surface of the cover plate 22 facing the encapsulation film 21 may be a concave-convex surface, thereby increasing the utilization rate of the incident light. The cover plate 22 includes a first cover plate and a second cover plate, the first cover plate is opposite to the first encapsulation layer, and the second cover plate is opposite to the second encapsulation layer; or the first cover plate is opposite to one side of the solar cell, and the second cover plate is opposite to the other side of the solar cell.

[0118] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present application, and in practical applications, various changes may be made to the embodiments in form and detail without departing from the spirit and scope of the present application. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present application, and therefore the scope of protection of the present application shall be subject to the scope defined in the claims.

Claims

1. A solar cell, characterized in that: The solar cell has a metal region and a non-metal region, including: A substrate having a front side and a back side that are opposite to each other; An inversion layer, the inversion layer is located on the surface of the substrate; the inversion layer includes a first inversion layer, the first inversion layer is located on the front side corresponding to the metal area; a first electrode, the first electrode being located on the substrate corresponding to the metal region and electrically connected to the first inversion layer; a passivation contact structure, the passivation contact structure being located on the back side of the metal region; A second electrode is located on the passivation contact structure corresponding to the metal area and is electrically connected to the passivation contact structure.

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

3. The solar cell according to claim 2, characterized in that: The inversion layer also includes a third inversion layer, which is located on the front side corresponding to the non-metallic area, has the same extension direction as the first inversion layer, is located between adjacent first inversion layers, and 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 is in the range of 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 is in the range of 2% to 20%.

5. The solar cell according to any one of claims 1 to 3, characterized in that: The orthographic projection of the passivation contact structure on the back surface overlaps with the orthographic projection of the inversion layer on the back surface; Alternatively, 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.

6. The solar cell according to claim 1, characterized in that The distance between the surface of the substrate including the inversion layer and the back side is a first distance, and the distance between the surface of the substrate not including the inversion layer and the back side is a second distance, and the first distance is greater than the second distance.

7. A method for preparing a solar cell, characterized in that: The solar cell has a metal region and a non-metal region, including: Providing a substrate, wherein the substrate has a front side and a back side that are oppositely disposed; forming an inversion layer, the inversion layer being located on the surface of the substrate; the inversion layer comprising a first inversion layer, the first inversion layer being located on the front side corresponding to the metal region; forming a first electrode, the first electrode being located on the substrate corresponding to the metal region and being electrically connected to the first inversion layer; forming a passivation contact structure, the passivation contact structure being located on the back side of the metal region; A second electrode is formed, where the second electrode is located on the passivation contact structure corresponding to the metal area and is electrically connected to the passivation contact structure.

8. The method for preparing a solar cell according to claim 7, characterized in that: The inversion layer further includes a second inversion layer, the front surface includes a first treated area and a first non-treated area, and the preparation method for forming the inversion layer includes: performing a doping treatment on the front surface of the substrate so that a portion of the thickness of the substrate is converted into a doped layer; The doped layer in the first processed area is removed, and the doped layer in the first non-processed area is retained as an inversion layer, wherein the inversion layer in the metal area is used as a first inversion layer, and part of the inversion layer in the non-metal area is used as a second inversion layer.

9. The method for preparing a solar cell according to claim 7, characterized in that: The front surface includes a second treated area and a second non-treated area, and the preparation method for forming the inversion layer includes: The second processing area of ​​the substrate is subjected to laser doping treatment so that a partial area of ​​the substrate is converted into an inversion layer.

10. A photovoltaic module, characterized in that: include: A battery string, formed by connecting a plurality of solar cells according to any one of claims 1 to 6 or a plurality of solar cells prepared by the preparation method according to any one of claims 7 to 9; A connecting component, wherein the connecting component is used to electrically connect two adjacent solar cells; A packaging film, used to cover the surface of the battery string; The cover plate is used to cover the surface of the packaging film facing away from the battery string.

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