Photovoltaic cell, preparation method thereof and photovoltaic module

Abstract

The embodiment of the invention relates to the photovoltaic field, and provides a photovoltaic cell and a preparation method thereof, and a photovoltaic module, and the photovoltaic cell comprises a substrate which is provided with a first surface; the anti-reflection layer is located on the first surface, and the anti-reflection layer is provided with an opening exposed out of the first surface; the grid line is located in the opening and located on the partial surface, away from the substrate, of the anti-reflection layer, and the orthographic projection of the opening on the substrate is located in the orthographic projection of at least part of the grid line on the substrate; wherein the material of the grid line comprises a low-burn-through type conductive material, and the grid line is in ohmic contact with the first surface exposed out of the opening. The embodiment of the invention is at least beneficial to improving the photoelectric conversion efficiency of the photovoltaic cell and reducing the preparation cost of the photovoltaic cell.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to the photovoltaic field, and in particular to a photovoltaic cell and a preparation method thereof, and a photovoltaic module. Background Art

[0002] Photovoltaic power generation refers to the conversion of solar energy into electrical energy through the photovoltaic effect of semiconductors. In order to transmit and collect the generated photogenerated carriers, grid lines are formed in solar cells. On the basis of setting grid lines, in order to improve the photoelectric conversion efficiency of photovoltaic cells, an anti-reflection layer is also set on the substrate surface of photovoltaic cells.

[0003] However, the anti-reflection layer located on the surface of the substrate of the photovoltaic cell will have an adverse effect on the contact performance between the grid line and the substrate, and the design of the anti-reflection layer and the grid line also needs to consider the cost issue. Based on this, how to balance the relationship between the anti-reflection effect of the anti-reflection layer on the photovoltaic cell and the contact performance between the grid line and the substrate is a problem that needs to be solved urgently. Summary of the invention

[0004] The embodiments of the present disclosure provide a photovoltaic cell and a method for preparing the same, and a photovoltaic module, which are at least beneficial for reducing the preparation cost of the photovoltaic cell while improving the photoelectric conversion efficiency of the photovoltaic cell.

[0005] According to some embodiments of the present disclosure, on one hand, the embodiments of the present disclosure provide a photovoltaic cell, comprising: a substrate, the substrate having a first surface; an anti-reflection layer, located on the first surface, the anti-reflection layer having an opening exposing the first surface; a gate line, located in the opening and located on a portion of the surface of the anti-reflection layer away from the substrate, the orthographic projection of the opening on the substrate being located in the orthographic projection of at least a portion of the gate line on the substrate; wherein a material of the gate line comprises a low burn-through conductive material, and the gate line is in ohmic contact with the first surface exposed by the opening.

[0006] In some embodiments, the low fire-through type conductive material includes copper and silver, and the content of copper in the low fire-through type conductive material is greater than or equal to the content of silver in the low fire-through type conductive material.

[0007] In some embodiments, the anti-reflection layer has a side wall constituting an opening, and the plane where the first surface is located is used as a reference plane, and the angle between the side wall and the reference plane is 45° to 150°; and / or the surface roughness of the side wall is less than or equal to 6.3 μm; and / or the gate line covers the side wall; and / or the contact resistivity between the gate line and the first surface is less than 5 mΩ·cm 2 .

[0008] In some embodiments, the gate line extends along a first direction, the second direction is perpendicular to the first direction, and along the second direction, a first width of the gate line is greater than or equal to a second width of the opening.

[0009] In some embodiments, the gate line extends along a first direction, and has two ends along the first direction, and a middle portion connecting the two ends; in the direction along the substrate pointing to the gate line, the area in the opening corresponding to the end is the first sub-opening, and the area in the opening corresponding to the middle portion is the second sub-opening; the second direction is perpendicular to the first direction, and along the second direction, the first sub-width of the end is greater than or equal to the second sub-width of the middle portion; and / or, the third sub-width of the first sub-opening is greater than or equal to the fourth sub-width of the second sub-opening.

[0010] In some embodiments, there is an ohmic contact interface between the gate line and the first surface, the gate line has silver microcrystals in contact with the ohmic contact interface, the ohmic contact interface has a first region in contact with the silver microcrystals, and the ratio of the area of ​​the first region to the area of ​​the ohmic contact interface is in the range of 60% to 90%.

[0011] According to some embodiments of the present disclosure, on the other hand, the embodiments of the present disclosure further provide a method for preparing a photovoltaic cell, comprising: providing a substrate, the substrate having a first surface: forming an initial anti-reflection layer covering the first surface; using a laser film opening process to remove at least part of the thickness of the initial anti-reflection layer along the direction of the substrate pointing to the initial anti-reflection layer to form an initial opening on the initial anti-reflection layer, and the remaining initial anti-reflection layer serves as the anti-reflection layer; using a first screen printing process to print a low burn-through type paste in the initial opening and on a portion of the surface of the anti-reflection layer away from the substrate; performing laser-assisted sintering on the low burn-through type paste to transform the low burn-through type paste into a grid line in ohmic contact with the first surface, and to transform the initial opening into an opening, and the orthographic projection of the opening on the substrate is located in the orthographic projection of at least part of the grid line on the substrate.

[0012] In some embodiments, in the step of performing a laser film opening process, an initial opening exposes the first surface; after performing a first screen printing process and before performing a laser-assisted sintering process, the contact resistivity between the low burn-through type paste and the first surface is a first resistivity; after performing a laser-assisted sintering process, the contact resistivity between the low burn-through type paste and the first surface is a second resistivity; wherein the second resistivity is less than the first resistivity, and in the step of performing a laser-assisted sintering process, the contact resistivity between the low burn-through type paste and the first surface decreases from the first resistivity to the second resistivity.

[0013] In some embodiments, the first surface includes a first area and a second area, the first area extends along the second direction, the first area extends along the first direction, and the first direction and the second direction intersect; the step of removing at least part of the thickness of the initial anti-reflection layer using a laser film opening process includes: removing at least part of the thickness of the initial anti-reflection layer located on the second area; before printing the low burn-through type slurry, the preparation method also includes: using a second screen printing process to print the burn-through type slurry on the initial anti-reflection layer located in the first area.

[0014] According to some embodiments of the present disclosure, another aspect of the embodiments of the present disclosure further provides a photovoltaic module, comprising: a cell string, formed by connecting the photovoltaic cells of any of the above items, or formed by connecting a plurality of photovoltaic cells formed by any of the above preparation methods; 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.

[0015] The technical solution provided by the embodiments of the present disclosure has at least the following advantages:

[0016] The material for designing the grid line includes a low burn-through conductive material, and the cost of the low burn-through conductive material is lower than that of the high burn-through conductive material, so as to reduce the preparation cost of the photovoltaic cell. On this basis, an opening is designed in the anti-reflection layer to expose the first surface of the substrate, and the orthographic projection of the opening on the substrate is located in the orthographic projection of at least part of the grid line on the substrate, so that the part of the grid line located in the opening can directly make ohmic contact with the first surface of the substrate. In other words, with the help of the opening design of the anti-reflection layer and the cooperation of the low burn-through conductive material, a good ohmic contact is formed between the grid line and the first surface. Moreover, the part of the grid line located on the surface of the part of the anti-reflection layer away from the substrate can be used to increase the cross-sectional area of ​​the grid line as a whole, so as to reduce the resistance of the grid line as a whole, thereby improving the conductivity of the grid line. In addition, based on the fact that the corrosion and burn-through performance of the low burn-through conductive material is very weak, the thickness of the anti-reflection layer can be thinned, which is not only conducive to reducing the preparation cost of the anti-reflection layer, but also conducive to reducing the parasitic absorption of light by the anti-reflection layer. Therefore, in the photovoltaic cell provided by the embodiment of the present disclosure, by means of the anti-reflection layer with openings and the grid lines including the low burn-through conductive material, it is at least beneficial to reduce the preparation cost of the photovoltaic cell while improving the photoelectric conversion efficiency of the photovoltaic cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings, and these exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise specified, the pictures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the traditional technology, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A schematic diagram of a first partial cross-sectional structure of a photovoltaic cell provided in one embodiment of the present disclosure;

[0019] Figure 2 A schematic diagram of a second partial cross-sectional structure of a photovoltaic cell provided in one embodiment of the present disclosure;

[0020] Figure 3 A third partial cross-sectional structural schematic diagram of a photovoltaic cell provided in one embodiment of the present disclosure;

[0021] Figure 4 A schematic diagram of a fourth partial cross-sectional structure of a photovoltaic cell provided in one embodiment of the present disclosure;

[0022] Figure 5 for Figure 1 A schematic diagram of an enlarged cross-sectional structure of a photovoltaic cell at a dotted box shown;

[0023] Figure 6 A schematic diagram of a first partial top view structure of a photovoltaic cell provided in one embodiment of the present disclosure;

[0024] Figure 7 A schematic diagram of a second partial top view structure of a photovoltaic cell provided in one embodiment of the present disclosure;

[0025] Figure 8 A schematic diagram of a first partial cross-sectional structure of a grid line and an anti-reflection layer in a photovoltaic cell provided in an embodiment of the present disclosure;

[0026] Fig. 9 A schematic diagram of a second partial cross-sectional structure of a grid line and an anti-reflection layer in a photovoltaic cell provided in an embodiment of the present disclosure;

[0027] Fig.10 A schematic diagram of a partially enlarged cross-sectional structure of a grid line and a substrate in a photovoltaic cell provided in an embodiment of the present disclosure;

[0028] Fig.11 for Fig.10 A schematic diagram of a cross-sectional structure of a grid line in a photovoltaic cell shown;

[0029] Fig.12 A schematic diagram of a partial cross-sectional structure of forming an initial anti-reflection layer in a method for preparing a photovoltaic cell provided in another embodiment of the present disclosure;

[0030] Fig.13 A schematic diagram of a first partial cross-sectional structure of forming an initial opening in a method for preparing a photovoltaic cell provided in another embodiment of the present disclosure;

[0031] Fig.14 A schematic diagram of a second partial cross-sectional structure of forming an initial opening in a method for preparing a photovoltaic cell provided in another embodiment of the present disclosure;

[0032] Fig.15 A schematic diagram of a third partial cross-sectional structure of forming an initial opening in a method for preparing a photovoltaic cell provided in another embodiment of the present disclosure;

[0033] Fig.16A schematic diagram of a fourth partial cross-sectional structure of forming an initial opening in a method for preparing a photovoltaic cell provided in another embodiment of the present disclosure;

[0034] Fig.17 A schematic diagram of a partial top view of the first surface of a substrate in a method for preparing a photovoltaic cell provided in another embodiment of the present disclosure;

[0035] Fig.18 A schematic diagram of a partial three-dimensional structure of a photovoltaic assembly provided by another embodiment of the present disclosure;

[0036] Fig.19 for Fig.18 Schematic diagram of a local cross-sectional structure along the M1-M2 section. DETAILED DESCRIPTION

[0037] As can be seen from the background art, the photoelectric conversion efficiency of photovoltaic cells needs to be improved, while the preparation cost of photovoltaic cells also needs to be reduced.

[0038] After analysis, it was found that in order to ensure that the gate line has excellent current collection ability, the gate line needs to penetrate the anti-reflection layer to form an ohmic contact with the substrate. The printing paste used to form the gate line generally needs to be sintered at high temperature to burn through the passivation layer at high temperature. Among them, the high-temperature sintering process easily causes damage and deformation to the substrate, and the degree of burn-through of the printing paste is difficult to control, which limits the improvement of the photoelectric conversion efficiency of the photovoltaic cell. In addition, the cost of the burn-through paste is high, which is not conducive to reducing the cost of photovoltaic cell preparation.

[0039] Moreover, one of the reasons why the current photoelectric conversion efficiency of solar cells is relatively low is that in order to achieve ohmic contact between the gate line and the surface of the substrate, a high-burn-through conductive material is usually used to prepare the gate line. On the one hand, when the gate line prepared by the high-burn-through conductive material is subjected to high-temperature sintering annealing, the high-burn-through conductive material is prone to excessive erosion of the anti-reflection layer, resulting in the final gate line to destroy the original anti-reflection layer to a large extent, affecting the performance of the anti-reflection layer; on the other hand, based on the high burn-through property of the high-burn-through conductive material, the high-burn-through conductive material used to form the gate line will be partially lost and cannot be used as a component of the gate line, resulting in fewer conductive grains formed in the final gate line, limited carrier transmission, and not conducive to the gate line to collect photocurrent, thereby limiting the photoelectric conversion efficiency of the solar cell.

[0040] The present disclosure provides a photovoltaic cell and a preparation method thereof, and a photovoltaic module. In the photovoltaic cell, the material for designing the grid line includes a low burn-through conductive material. The cost of the low burn-through conductive material is lower than that of the high burn-through conductive material, so as to reduce the preparation cost of the photovoltaic cell. On this basis, an opening is designed in the anti-reflection layer to expose the first surface of the substrate, and the orthographic projection of the opening on the substrate is located in the orthographic projection of at least part of the grid line on the substrate, so that the part of the grid line located in the opening can directly make ohmic contact with the first surface of the substrate. In other words, with the help of the opening design of the anti-reflection layer and the cooperation of the low burn-through conductive material, a good ohmic contact is formed between the grid line and the first surface. Moreover, the part of the grid line located on the surface of the part of the anti-reflection layer away from the substrate can be used to increase the cross-sectional area of ​​the grid line as a whole, so as to reduce the resistance of the grid line as a whole, thereby improving the conductivity of the grid line. In addition, based on the fact that the corrosion and burn-through performance of the low burn-through conductive material is very weak, the thickness of the anti-reflection layer can be thinned, which is not only conducive to reducing the preparation cost of the anti-reflection layer, but also conducive to reducing the parasitic absorption of light by the anti-reflection layer. Therefore, in the photovoltaic cell provided by the embodiment of the present disclosure, by means of the anti-reflection layer with openings and the grid lines including the low burn-through conductive material, it is at least beneficial to reduce the preparation cost of the photovoltaic cell while improving the photoelectric conversion efficiency of the photovoltaic cell.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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).

[0045] 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.

[0046] 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.

[0047] In the accompanying drawings corresponding to the embodiments of the present application, the thickness and area of ​​the layer are magnified 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 can be "directly" located on the surface of the other component, or a third component can 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 "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.

[0048] 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, a film, a region, or a 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, a film, a region, a plate, etc. is "directly located on" another component, or when a component such as a layer, a film, a region, a plate, etc. is located on the surface of another component, it means that no other components are located in between.

[0049] 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 components" are also intended to include plural forms unless the context clearly indicates otherwise. Among them, components include components such as layers, films, regions, or plates.

[0050] The following will describe the various embodiments of the present disclosure 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 disclosure, many technical details are provided in order to enable the reader to better understand the embodiments of the present disclosure. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the embodiments of the present disclosure can be implemented.

[0051] An embodiment of the present disclosure provides a photovoltaic cell, which will be described in detail below with reference to the accompanying drawings.

[0052] refer to Figure 1 , Figure 1 A schematic diagram of a first partial cross-sectional structure of a photovoltaic cell provided in an embodiment of the present disclosure, the photovoltaic cell comprising: a substrate 100, the substrate 100 having a first surface 110; an anti-reflection layer 101, located on the first surface 110, the anti-reflection layer 101 having an opening 111 exposing the first surface 110; a gate line 102, located in the opening 111 and located on a portion of the surface of the anti-reflection layer 101 away from the substrate 100, the orthographic projection of the opening 111 on the substrate 100 is located in the orthographic projection of at least a portion of the gate line 102 on the substrate 100; wherein the material of the gate line 102 comprises a low burn-through conductive material, and the gate line 102 is in ohmic contact with the first surface 110 exposed by the opening 111.

[0053] It should be noted that the low burn-through conductive material has very weak or even no corrosion and burn-through performance on the anti-reflection layer 101 and the substrate 100. Therefore, under normal temperature and pressure, even if the gate line 102 including the low burn-through conductive material is in direct contact with the substrate 100, it will not cause significant damage to the substrate 100. Moreover, compared with the commonly used high burn-through conductive materials on the market, the cost of the low burn-through conductive material is lower. The commonly used high burn-through conductive materials and the low burn-through conductive materials provided in one embodiment of the present disclosure will be exemplified later, and will not be described in detail here.

[0054] Based on this, an anti-reflection layer 101 having an opening 111 and a gate line 102 including a low-burn-through conductive material are designed, and the orthographic projection of the opening 111 on the substrate 100 is located in the orthographic projection of at least part of the gate line 102 on the substrate 100, so that the portion of the gate line 102 located in the opening 111 can directly make ohmic contact with the first surface 110 of the substrate 100, and the gate line 102 including the low-burn-through conductive material will not cause damage to the first surface 110. In other words, the opening 111 of the anti-reflection layer 101 is used to remove the portion of the anti-reflection layer 101 directly facing the gate line 102, and the corrosion and burn-through performance of the low-burn-through conductive material is very weak, so that a good ohmic contact is formed between the gate line 102 and the first surface 110, and further corrosion of the low-burn-through conductive material on the first surface 110 is avoided. Moreover, the portion of the gate line 102 located on the surface of the anti-reflection layer 101 away from the substrate 100 can be used to increase the overall cross-sectional area of ​​the gate line 102 to reduce the overall resistance of the gate line 102, thereby improving the conductivity of the gate line 102. Therefore, the photovoltaic cell provided in an embodiment of the present disclosure is at least conducive to reducing the preparation cost of the photovoltaic cell while improving the photoelectric conversion efficiency of the photovoltaic cell.

[0055] Moreover, based on the fact that the corrosion and burn-through performance of the low burn-through conductive material is very weak, on the basis of satisfying the performance of the anti-reflection layer 101, the thickness of the anti-reflection layer 101 can be thinned along the direction Z pointing from the substrate 100 to the gate line 102. Not only will the portion of the gate line 102 located on the surface of the anti-reflection layer 101 away from the substrate 100 not erode the anti-reflection layer 101, but the thinning of the anti-reflection layer 101 can also reduce the preparation cost of the anti-reflection layer 101, so as to further reduce the preparation cost of the photovoltaic cell. The thinning of the anti-reflection layer 101 is also beneficial to reducing the parasitic absorption of light by the anti-reflection layer 101, so that more light energy can be absorbed by the substrate 100, thereby further improving the photoelectric conversion efficiency of the photovoltaic cell.

[0056] In some embodiments, compared to the case where the anti-reflection layer is not opened and the material of the gate line is selected as a high-burn-through conductive material, the photovoltaic cell provided by an embodiment of the present disclosure is beneficial for reducing the preparation cost of the gate line 102 by about 15%, improving the photoelectric conversion efficiency Eta by about 0.1%, improving the open circuit voltage Uoc by about 0.002%, and improving the fill factor FF by about 0.3%.

[0057] An embodiment of the present disclosure will be described in more detail below with reference to the accompanying drawings.

[0058] In some embodiments, the low fire-through type conductive material may include copper and silver, and the content of copper in the low fire-through type conductive material is greater than or equal to the content of silver in the low fire-through type conductive material.

[0059] It is worth noting that the high burn-through conductive material can be a conductive paste in which the metal material only includes silver, or a conductive paste in which the metal material only includes copper. Among them, the cost of the conductive paste in which the metal material only includes silver is relatively high, which is not conducive to reducing the preparation cost of photovoltaic cells; the degree of burn-through of the anti-reflection layer and the substrate of the conductive paste in which the metal material only includes copper is not easy to control, and it is easy to cause large etching damage to the anti-reflection layer or the substrate, which can easily lead to a decrease in the photoelectric conversion efficiency of the photovoltaic cell. Based on this, a low burn-through conductive material including copper and silver is designed to replace the common high burn-through conductive material on the market, which is not only conducive to reducing the preparation cost of photovoltaic cells, but also, by virtue of the fact that the corrosion and burn-through performance of the low burn-through conductive material is very weak, a good ohmic contact is formed between the grid line 102 and the first surface 110, avoiding further corrosion of the low burn-through conductive material on the first surface 110, further improving the photoelectric conversion efficiency of the photovoltaic cell, and also helping to reduce the thickness of the anti-reflection layer 101, which is not only conducive to further reducing the preparation cost of photovoltaic cells, but also conducive to further improving the photoelectric conversion efficiency of photovoltaic cells.

[0060] In some examples, the copper content in the low burn-through conductive material may be 50% to 90%. For example, the copper content in the low burn-through conductive material may be 52%, 55%, 58%, 60%, 64%, 65%, 68%, 70%, 72%, 75%, 78%, 80%, 83%, 85% or 88%, etc.

[0061] In some embodiments, the substrate 100 has a relative front and back sides. In some cases, the photovoltaic cell is a single-sided cell, then the front side of the substrate can be used as a light-receiving surface for receiving incident light, and the back side is used as a backlight surface; in other cases, the solar cell is a double-sided cell, then both the front side and the back side of the substrate can be used as light-receiving surfaces, both can be used to receive incident light, wherein the front side is the primary light-receiving surface, and the back side is the secondary light-receiving surface. It is worth noting that the backlight surface referred to in the embodiments of the present disclosure can also receive incident light, but the degree of receiving the incident light is weaker than the degree of receiving the incident light by the light-receiving surface, and therefore is defined as a backlight surface.

[0062] In some examples, reference Figure 2 , Figure 2A schematic diagram of a second partial cross-sectional structure of a photovoltaic cell provided in an embodiment of the present disclosure, wherein the first surface 110 may be the back surface, and the base 100 may include a substrate 103, a tunneling layer 104, and a doped conductive layer 105 stacked in sequence, and the first surface 110 is the surface of the doped conductive layer 105 away from the tunneling layer 104. The tunneling layer 104 and the doped conductive layer 105 constitute a passivation contact structure, and the passivation contact structure provides good surface passivation for the surface of the substrate 103, which is beneficial to reducing the metal contact recombination current and improving the open circuit voltage and short circuit current of the photovoltaic cell. In other words, the photovoltaic cell may be a TOPCON (Tunnel Oxide Passivated Contact) cell.

[0063] In other examples, reference Figure 3 , Figure 3 This is a schematic diagram of a third partial cross-sectional structure of a photovoltaic cell provided by an embodiment of the present disclosure, wherein the first surface 110 may be the front side, the substrate 100 includes an emitter 106, and the first surface 110 includes the surface of the emitter 106. It should be noted that the emitter 106 may be formed based on the substrate 100, and thus the emitter 106 is embedded in the substrate 100. Figure 3 In the figure, the emitter 106 is embedded in the substrate 100, and the emitter 106 is a selective emitter directly opposite to the gate line 102. In actual applications, the emitter can be embedded in the entire first surface of the substrate, or the substrate includes the substrate or the emitter, and the emitter is additionally formed on the surface of the substrate.

[0064] In some other examples, reference Figure 4 , Figure 4 This is a schematic diagram of a fourth partial cross-sectional structure of a photovoltaic cell provided in an embodiment of the present disclosure. The first surface 110 can be the back side, the anti-reflection layer 101 located on the first surface 110 can be regarded as the back side anti-reflection layer, the opening 111 of the anti-reflection layer 101 can be regarded as the back side opening, and the grid line 102 in ohmic contact with the first surface 110 can be regarded as the back side grid line.

[0065] On this basis, the front side of the substrate 100 can be regarded as the second surface 120, and the photovoltaic cell can also include: a front anti-reflection layer 107, located on the second surface 120, and the front anti-reflection layer 107 has a front opening 117 exposing the second surface 120; a front grid line 108, located in the front opening 117 and located on a portion of the surface of the front anti-reflection layer 107 away from the substrate 107, and the orthographic projection of the front opening 117 on the substrate 100 is located in the orthographic projection of at least part of the front grid line 108 on the substrate 100; wherein, the material of the front grid line 108 includes a low burn-through conductive material, and the front grid line 108 is in ohmic contact with the second surface 120 exposed by the front opening 117.

[0066] It is worth noting that in order to distinguish the grid lines 102 from the front grid lines 108, Figure 4 Different filling methods are used to draw the grid lines 102 and the front grid lines 108; in order to distinguish the anti-reflection layer 101 and the front anti-reflection layer 107, Figure 4 Different filling methods are used to draw the anti-reflection layer 101 and the front anti-reflection layer 107.

[0067] It should be noted that, in actual applications, the first surface may also be the front surface, and the back surface of the substrate may be regarded as the second surface, and the second surface also has an anti-reflection layer and a grid line similar to the above examples. In addition, in the above various examples, whether it is the grid line 102 or the front grid line 108, it can be a main grid, a fine grid, or a main grid and a fine grid. According to actual needs, the grid line that needs to be designed to include a low burn-through conductive material in the photovoltaic cell can be selected, and the anti-reflection layer facing the part of the grid line can be opened to reduce the preparation cost of the grid line and improve the photoelectric conversion efficiency of the photovoltaic cell. In addition, for a certain grid line 102, based on the type of grid line indicated by the grid line 102, the extension direction of the grid line 102, that is, the first direction X, changes with the change of the type of the grid line. For example, the extension direction of the grid line 102 as the main grid is different from the extension direction of the grid line 102 as the auxiliary grid. In actual applications, the first direction can be flexibly adapted according to the specific application scenario of the grid line described in an embodiment of the present disclosure.

[0068] In some embodiments, reference Figures 1 to 7 , the orthographic projection of the opening 111 on the substrate 100 is located in the orthographic projection of at least part of the gate line 102 on the substrate 100, including the following situations: the photovoltaic cell includes a plurality of gate lines 102 arranged at intervals along the second direction Y, the gate lines 102 extend along the first direction X, each gate line 102 is located in at least one opening 111, and the orthographic projection of any opening 111 on the substrate 100 is located in the orthographic projection of a gate line 102 on the substrate 100. In other words, the gate line 102 fills any opening 111, so that the gate line 102 can fully contact the first surface 110 exposed by the opening 111, ensuring that the gate line 102 and the first surface 110 have sufficient ohmic contact area, so as to improve the conductivity between the gate line 102 and the first surface 110, and ensure that the gate line 102 has a higher photogenerated carrier collection ability.

[0069] It should be noted that in actual applications, due to the influence of the preparation process, for a certain number of openings, the portion of the gate line located in the opening does not fill the opening. In other words, the orthographic projection of the opening on the substrate is not located in the orthographic projection of the gate line on the substrate, and the orthographic projections of the two only partially overlap.

[0070] In some embodiments, reference Figure 5 , Figure 5 for Figure 1The schematic diagram of an enlarged cross-sectional structure of the dotted box in the photovoltaic cell shown in the figure shows that the anti-reflection layer 101 has a side wall 101a constituting an opening 111. Taking the plane where the first surface 110 is located as a reference plane, the angle β between the side wall 101a and the reference plane is 45° to 150°.

[0071] It is worth noting that, compared with the depression formed in the anti-reflection layer by the high-burn-through conductive material through high-temperature sintering, the side wall 101a constituting the opening 111 in the anti-reflection layer 101 is flatter, and it can be clearly seen that there is an angle β between the side wall 101a and the reference plane. In other words, along the direction Z from the substrate 100 to the gate line 102, the interface where the gate line 102 contacts the anti-reflection layer 101, that is, the side wall 101a is a relatively flat surface, which is different from the interface where the high-burn-through conductive material contacts the anti-reflection layer after high-temperature sintering, which is relatively rough. It can be understood that different areas of the interface where the high-burn-through conductive material contacts the anti-reflection layer after high-temperature sintering are eroded to different degrees by the high-burn-through conductive material, which results in large differences between different areas of the interface where the high-burn-through conductive material contacts the anti-reflection layer.

[0072] In addition, the side wall 101a is flatter, and the edge where the gate line 102 contacts the anti-reflection layer 101 is also smoother. The gate line 102 will not have too large a difference in conductivity in different areas due to too large a difference in edge morphology, which is beneficial to improving the stability of the overall conductivity of the gate line 102 and avoiding the loss of carriers caused by sudden changes in conductivity in the gate line 102.

[0073] In some examples, the angle β can be 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, 90°, 95°, 100°, 105°, 110°, 115°, 120°, 125°, 130°, 135°, 140° or 145°, etc.

[0074] In some embodiments, reference Figure 5 , the surface roughness of the side wall 101a is less than or equal to 6.3 μm. In other words, the side wall 101a is a relatively flat surface.

[0075] In some embodiments, reference Figure 5 , the gate line 102 covers the side wall 101a. This is conducive to further ensuring that the gate line 102 fills the opening 111, ensuring that the gate line 102 and the first surface 110 have sufficient ohmic contact area, so as to improve the photogenerated carrier collection capability of the gate line 102.

[0076] In some embodiments, the contact resistivity between the gate line 102 and the first surface 110 is less than 5 mΩ·cm 2In other words, based on the design of the opening 111 in the anti-reflection layer 101, the gate line 102 including the low burn-through conductive material does not need to have a strong burn-through performance, and can also have a low contact resistivity with the first surface 110, that is, a good ohmic contact with the first surface 110 is achieved. In some examples, the gate line 102 including the low burn-through conductive material can be a gate line formed by laser-assisted sintering of the low burn-through conductive material.

[0077] In some embodiments, in conjunction with reference Figures 1 to 7 The gate line 102 extends along the first direction X, the second direction Y is perpendicular to the first direction X, and along the second direction Y, the first width W1 of the gate line 102 is greater than or equal to the second width W2 of the opening 111 .

[0078] In this way, on the one hand, it is avoided that the opening 111 with a second width W2 that is too large is set on the anti-reflection layer 101, which may affect the structural stability of the anti-reflection layer 101; on the other hand, the first width W1 being greater than or equal to the second width W2 is conducive to ensuring that the gate line 102 fills the opening 111, so as to ensure a sufficient ohmic contact area between the gate line 102 and the first surface 110, and to make a partial area of ​​the gate line 102 located on the surface of the anti-reflection layer 101 away from the substrate 100, thereby increasing the overall cross-sectional area of ​​the gate line 102, so as to reduce the overall resistance of the gate line 102, and further improve the photogenerated carrier collection capability of the gate line 102.

[0079] In some cases, in conjunction with reference Figures 5 to 7 For any gate line 102, the specific values ​​of the first width W1 of different regions of the gate line 102 along the first direction X may be the same or different; and for any gate line 102, the gate line 102 is located in at least one opening 111. In some cases, in combination with reference Figure 5 and Figure 6 , a gate line 102 is located in an opening 111, the opening 111 extends along the first direction X and the opening 111 penetrates the anti-reflection layer 101 along the first direction X, and the anti-reflection layer 101 has two side walls 101a that are opposite to each other along the second direction Y and constitute the opening 111; in other cases, combined with reference Figure 5 and Figure 7 A gate line 102 is located in a plurality of openings 111, and the plurality of openings 111 are arranged at intervals along the first direction X. The anti-reflection layer 101 has three or four side walls 101a constituting the openings 111. Not only may the specific values ​​of the second width W2 of different regions of the same opening 111 along the first direction X be the same or different, but also the specific values ​​of the second width W2 of different openings 111 may be the same or different.

[0080] in, Figure 6A schematic diagram of a first partial top view structure of a photovoltaic cell provided in one embodiment of the present disclosure; Figure 7 A schematic diagram of a second partial top view structure of a photovoltaic cell provided in one embodiment of the present disclosure.

[0081] Based on this, along the second direction Y, the first width W1 of the gate line 102 is greater than or equal to the second width W2 of the opening 111 means that: along the first direction X, in a plurality of cross sections parallel to the second direction Y, for the gate line 102 and the opening 111 on any cross section, the first width W1 of the gate line 102 is greater than or equal to the second width W2 of the opening 111 corresponding to the gate line 102, and the opening 111 corresponding to the gate line 102 is the opening 111 filled by the gate line 102. Therefore, the average value of the first width W1 of the gate line 102 is also greater than or equal to the average value of the second width W2 of the opening 111 corresponding to the gate line 102.

[0082] In some examples, the ratio of the second width W2 to the first width W1 can range from 1 / 100 to 1. For example, the ratio of the second width W2 to the first width W1 ranges from 1 / 100 to 1 / 90, 1 / 90 to 1 / 80, 1 / 80 to 1 / 70, 1 / 70 to 1 / 60, 1 / 60 to 1 / 50, 1 / 50 to 1 / 40, 1 / 40 to 1 / 30, 1 / 30 to 1 / 20, 1 / 20 to 1 / 10 or 1 / 10 to 1, etc.

[0083] In some examples, the first width W1 of the gate line 102 may be 10 μm to 300 μm, for example, the first width W1 may be 50 μm, 100 μm, 150 μm, 200 μm or 250 μm, etc.; the second width W2 of the opening 111 may be 3 μm to 100 μm, for example, the second width W2 may be 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm or 90 μm, etc.

[0084] In some embodiments, reference Figure 6 or Figure 7 , the gate line 102 extends along the first direction X, and the gate line 102 has two ends 112 along the first direction X, and a middle portion 122 connecting the two ends 112; in the direction Z from the substrate 100 to the gate line 102, the area of ​​the opening 111 corresponding to the end 112 is the first sub-opening 121, and the area of ​​the opening 111 corresponding to the middle portion 122 is the second sub-opening 131. It should be noted that, Figure 6 and Figure 7 The end portion 112 and the middle portion 122 of a grid line 102 are divided by a dotted line, and Figure 6In the figure, a first sub-opening 121 and a second sub-opening 131 in an opening 111 are divided by dotted lines to clearly illustrate the relative positional relationship between the gate line 102 and the opening 111. Figure 6 and Figure 7 The grid lines 102 are all drawn in a perspective manner.

[0085] The following describes in detail the size relationship between the end portion 112 and the first sub-opening 121 , and the size relationship between the middle portion 122 and the second sub-opening 131 .

[0086] In some cases, reference Figure 6 , the second direction Y is perpendicular to the first direction X, and along the second direction Y, the first sub-width W11 of the end portion 112 is greater than the second sub-width W12 of the middle portion 122. In practical applications, the first sub-width of the end portion may also be equal to the second sub-width of the middle portion. In other words, a gate line is not specifically divided into an end portion and a middle portion.

[0087] It is worth noting that the photovoltaic cell has a central area and a peripheral area surrounding the central area. Generally, the peripheral area is subjected to greater external pressure, and the peripheral area is more likely to suffer damage such as hidden cracks due to excessive force. Based on this, the grid line 102 is designed to have an end 112 and a middle part 122, and the end 112 is located in the peripheral area, and the middle part 122 is located in the central area. The first sub-width W11 of the end 112 is greater than or equal to the second sub-width W12 of the middle part 122, which is beneficial to reduce the probability of the end 112 being broken due to excessive force, thereby facilitating the overall structural stability of the grid line 102, and further improving the overall conductive performance of the grid line 102 with the help of the end 112 with a larger first sub-width W11.

[0088] It should be noted that, in conjunction with the reference Figure 5 and Figure 6 The end portion 112 and the middle portion 122 are different regions of the gate line 102 along the first direction X, the first sub-width W11 of the end portion 112 is the first width W1 of a certain region of the gate line 102 along the first direction X, and the second sub-width W12 of the middle portion 122 is the first width W1 of another region of the gate line 102 along the first direction X.

[0089] In some examples, combined with reference Figure 5 and Figure 6 On the basis that the first sub-width W11 of the end portion 112 is greater than the second sub-width W12 of the middle portion 122, the opening 111 extends along the first direction X and the opening 111 penetrates the anti-reflection layer 101 along the first direction X, the third sub-width W21 of the first sub-opening 121 is the second width W2 of a certain area of ​​the opening 111 along the first direction X, and the fourth sub-width W22 of the second sub-opening 131 is the second width W2 of another area of ​​the opening 111 along the first direction X.

[0090] In other examples, combined with reference Figure 5 and Figure 7 On the basis that the first sub-width W11 of the end portion 112 is greater than the second sub-width W12 of the middle portion 122, the plurality of openings 111 are arranged at intervals along the first direction X, the third sub-width W21 of the first sub-opening 121 is the second width W2 of a certain opening 111 corresponding to the end portion 112 among the plurality of openings 111 arranged at intervals along the first direction X, and the fourth sub-width W22 of the second sub-opening 131 is the second width W2 of another opening 111 corresponding to the middle portion 122 among the plurality of openings 111 arranged at intervals along the first direction X.

[0091] In the above two examples, the third sub-width W21 of the first sub-opening 121 is designed to be greater than or equal to the fourth sub-width W22 of the second sub-opening 131, and matches the first sub-width W11 of the gate line 102 that is greater than or equal to the second sub-width W12 of the middle portion 122, so as to further ensure that the gate line 102 fills the opening 111, and the second width W2 of the opening 111 corresponding to the area where the first width W1 of the gate line 102 increases is also increased accordingly, which is also conducive to further improving the ohmic contact area between the gate line 102 and the substrate 100. In addition, Figure 6 and Figure 7 In the example, the third sub-width W21 of the first sub-opening 121 is larger than the fourth sub-width W22 of the second sub-opening 131 . In actual applications, the third sub-width of the first sub-opening may also be equal to the fourth sub-width of the second sub-opening.

[0092] It should be noted that in actual applications, under the premise that the first width of the gate line along the second direction is greater than or equal to the second width of the opening, when the first sub-width at the end is greater than the second sub-width in the middle, the third sub-width of the first sub-opening may be greater than or equal to the fourth sub-width of the second sub-opening; when the first sub-width at the end is equal to the second sub-width in the middle, the third sub-width of the first sub-opening may also be greater than or equal to the fourth sub-width of the second sub-opening.

[0093] In some embodiments, reference Figure 8 or Fig. 9 The gate line 102 extends along the first direction X, the anti-reflection layer 101 has a plurality of openings 111 arranged at intervals along the first direction X, and a gate line 102 is located in the plurality of openings 111; a first spacing D1 is provided between two adjacent openings 111 along the first direction X, and a ratio of a first length L1 of the opening 111 in the first direction X to the first spacing D1 is in a range of 1 / 40 to 10 / 1.

[0094] in, Figure 8 A schematic diagram of a first partial cross-sectional structure of a grid line and an anti-reflection layer in a photovoltaic cell provided in an embodiment of the present disclosure; Fig. 9A schematic diagram of a second partial cross-sectional structure of a grid line and an anti-reflection layer in a photovoltaic cell provided in an embodiment of the present disclosure.

[0095] If the ratio of the first length L1 of the opening 111 to the first spacing D1 is less than 1 / 40, the portion of the anti-reflection layer 101 having the opening 111 in contact with the gate line 102 accounts for too small a proportion. In other words, the portion of the entire gate line 102 that can make ohmic contact with the first surface 110 with the help of the opening 111 accounts for too small a proportion of the entire gate line 102, which is not conducive to increasing the ohmic contact area between the entire gate line 102 and the first surface 110; if the ratio of the first length L1 of the opening 111 to the first spacing D1 is greater than 10 / 1, the portion of the anti-reflection layer 101 having the opening 111 in contact with the gate line 102 accounts for too large a proportion, and the portion of the anti-reflection layer 101 located between adjacent openings 111 is small in size and easily collapses due to force, which in turn affects the ohmic contact between the gate line 102 and the first surface 110. Therefore, the ratio of the first length L1 of the opening 111 to the first spacing D1 is designed to be in the range of 1 / 40 to 10 / 1, which is beneficial for ensuring that the structural stability of the anti-reflection layer 101 itself is relatively high while making the proportion of the portion of the anti-reflection layer 101 having the opening 111 in contact with the gate line 102 appropriate, so as to ensure that the gate line 102 has a sufficient ohmic contact area with the first surface 110 via the opening 111, so as to improve the conductivity between the gate line 102 and the first surface 110.

[0096] It is worth noting that, based on different preparation methods of the opening 111 of the anti-reflection layer 101, the ratio of the first length L1 of the opening 111 to the first distance D1 has the following two situations:

[0097] In some cases, reference Figure 8 The opening 111 in the anti-reflection layer 101 is prepared by a continuous dot-shaped film opening method, and the ratio of the first length L1 of the opening 111 in the first direction X to the first spacing D1 ranges from 1 / 5 to 10 / 1. For example, the ratio between the two can be 1 / 4, 1 / 3, 1 / 2, 1, 2, 3, 4, 5, 6, 7, 8 or 9, etc.

[0098] In other cases, reference Fig. 9 The opening 111 in the anti-reflection layer 101 is prepared by a continuous line segment-shaped film opening method. The ratio of the first length L1 of the opening 111 in the first direction X to the first spacing D1 is in the range of 1 / 40 to 1 / 5. For example, the ratio between the two can be 1 / 35, 1 / 30, 1 / 25, 1 / 20, 1 / 15, 1 / 10, 1 / 5, 1, 1.5, 2, 2.5, 3, 3.5, 4 or 4.5, etc.

[0099] In other embodiments, reference Figure 6, the gate line 102 extends along the first direction X, the anti-reflection layer 101 has an opening 111 extending along the first direction X and penetrating the anti-reflection layer 101 along the first direction X, and the gate line 102 corresponds to the opening 111 one by one. It is worth noting that in some cases, the gate line including the low burn-through type conductive material is the auxiliary grid, and the material of the main grid that collects the current on the auxiliary grid is different from the material of the auxiliary grid. For example, the material of the main grid includes a high burn-through type conductive material. When the opening penetrates the anti-reflection layer along the first direction, the part of the main grid that is in contact with the auxiliary grid may also be located in the opening.

[0100] It should be noted that, in order to ensure that there is sufficient ohmic contact area between the gate line and the first surface exposed by the opening, in actual applications, based on the different types of openings selected to be in contact with a gate line, the ratio of the first width of the gate line to the second width of the opening can be designed to be different. For example, if there are multiple openings in contact with a gate line, and the proportion of the portion of the anti-reflection layer in contact with the gate line with the openings is low, the ratio of the first width of the gate line to the second width of the opening can be designed to be close to or equal to 1, that is, the difference between the first width and the second width is small, so as to increase the area of ​​the first surface exposed by the opening; if the opening in contact with a gate line is an opening that penetrates the anti-reflection layer along the first direction, the ratio of the first width of the gate line to the second width of the opening can be designed to be larger, that is, the difference between the first width and the second width is larger.

[0101] In some embodiments, reference Fig.10 , Fig.10 A schematic diagram of a partially enlarged cross-sectional structure of a grid line and a substrate in a photovoltaic cell provided in an embodiment of the present disclosure, wherein an ohmic contact interface 130 is provided between the grid line 102 and the first surface 110, the grid line 102 comprises silver microcrystals 132a in contact with the ohmic contact interface 130, the ohmic contact interface 130 comprises a first region in contact with the silver microcrystals 132a, and the ratio of the area of ​​the first region to the area of ​​the ohmic contact interface 130 is in a range of 60% to 90%.

[0102] It is worth noting that most of the area of ​​the gate line 102 that constitutes the ohmic contact interface 130 is the first area, and the first area is composed of silver microcrystals 132a. Multiple silver microcrystals 132a can form a thin layer for carrier transmission at the ohmic contact interface 130. The thin layer is in ohmic contact with the first surface 110 of the substrate 100, which is conducive to reducing the contact resistivity between the gate line 102 and the first surface 110, promoting the formation of a good ohmic contact between the gate line 102 and the first surface 110, and improving the ability of the carriers in the substrate 100 to be transmitted to the gate line 102 that penetrates the anti-reflection layer 101, thereby improving the collection efficiency of the gate line 102 for photogenerated carriers. Moreover, the larger the proportion of the first area in the ohmic contact interface 130, the more conducive it is to reducing the contact resistivity between the gate line 102 and the first surface 110. In addition, the area other than the first area on the ohmic contact interface 130 may include a small amount of silver particles 142a or silver-coated copper particles 152a.

[0103] In some examples, the ratio of the area of ​​the first region to the area of ​​the ohmic contact interface 130 may be 65%, 68%, 70%, 72%, 75%, 80%, 84%, 85%, 88%, etc.

[0104] In some embodiments, in conjunction with reference Fig.10 and Fig.11 , Fig.11 for Fig.10 A schematic diagram of a cross-sectional structure of a grid line in a photovoltaic cell is shown. In the direction Z pointing from the substrate 100 to the grid line 102, the grid line 102 includes a bottom 132, a transition portion 142 and a top 152 connected in sequence, the bottom 132 is in ohmic contact with the first surface 110, the bottom 132 includes silver microcrystals 132a, the transition portion 142 includes silver particles 142a, and the top 152 includes silver-coated copper particles 152a, wherein the size of the silver microcrystals 132a is smaller than the size of the silver particles 142a.

[0105] It should be noted that Fig.11 The bottom 132, transition part 142 and top 152 of the gate line 102 are roughly divided by dotted lines. In practical applications, the approximate areas of the bottom 132, transition part 142 and top 152 can be defined according to the specific distribution of silver microcrystals 132a, silver particles 142a and silver-coated copper particles 152a in the gate line 102.

[0106] It is worth noting that the main conductive component in the bottom 132 is silver microcrystals 132a, which may also be doped with a small amount of silver particles 142a and / or silver-coated copper particles 152a. In other words, the content of silver microcrystals 132a in the bottom 132 accounts for a higher proportion than the content of other components in the bottom 132; the main conductive component in the transition portion 142 is silver particles 142a, which may also be doped with a small amount of silver microcrystals 132a and / or silver-coated copper particles 152a. In other words, the content of silver particles 142a in the transition portion 142 accounts for a higher proportion than the content of other components in the transition portion 142; the main conductive component in the top 152 is silver-coated copper particles 152a, which may also be doped with a small amount of silver microcrystals 132a and / or silver particles 142a. In other words, the content of silver-coated copper particles 152a in the top 152 accounts for a higher proportion than the content of other components in the top 152.

[0107] Among them, the bottom 132, i.e., a thin layer for carrier transmission formed by multiple silver microcrystals 132a at the ohmic contact interface 130 in the above description, is mainly used to reduce the contact resistivity between the gate line 102 and the first surface 110; the transition portion 142 and the top 152 serve as a transmission layer for carriers in the gate line 102, and are mainly used to reduce the line resistance of the gate line 102, thereby facilitating further improving the transmission efficiency of carriers in the gate line 102.

[0108] In some cases, the silver microcrystals 132a, the silver particles 142a, and the silver-coated copper particles 152a are all spherical particles, and the sizes of the silver microcrystals 132a, the silver particles 142a, and the silver-coated copper particles 152a may all refer to the diameters of the spherical particles.

[0109] In some examples, the size of the silver microcrystals 132 a is 5 nm to 20 nm, the size of the silver particles 142 a is 20 nm to 100 nm, and the size of the silver-coated copper particles 152 a is 1 μm to 10 μm.

[0110] In the above-mentioned various embodiments, in addition to the silver microcrystals 132a, silver particles 142a and silver-coated copper particles 152a, the gate line 102 also includes a filler filled between the silver microcrystals 132a, silver particles 142a and silver-coated copper particles 152a. The filler mainly includes glass or resin, which is used to fill and adhere the silver microcrystals 132a, silver particles 142a and silver-coated copper particles 152a.

[0111] In some embodiments, reference Figure 1 or Figure 3, along the direction Z from the substrate 100 to the gate line 102, the depth H1 of the opening 111 is 10nm to 200nm. It should be noted that the depth H1 of the opening 111 is the thickness of the anti-reflection layer 101 in the direction Z. In other words, the thickness of the anti-reflection layer 101 in the direction Z is 10nm to 200nm.

[0112] It is worth noting that, compared with the gate lines made of high-burn-through conductive materials, which need to match the anti-reflection layer with a thicker thickness to avoid further damage to the substrate after the gate lines burn through the anti-reflection layer, in one embodiment of the present disclosure, the design of the opening 111 on the anti-reflection layer 101 is combined with the gate line 102 including the low-burn-through conductive material, which can not only adapt to the anti-reflection layer 101 with a thicker thickness that matches the high-burn-through conductive material, but also can thin the thickness of the anti-reflection layer 101. Moreover, the thinning of the anti-reflection layer 101 can not only reduce the preparation cost of the anti-reflection layer 101, but also help to reduce the parasitic absorption of light by the anti-reflection layer 101, so that more light energy is absorbed by the substrate 100, thereby further improving the photoelectric conversion efficiency of the photovoltaic cell. Therefore, the depth H1 of the opening 111, that is, the numerical range of the thickness of the anti-reflection layer 101 in the direction Z can be designed to be as small as 10nm, or as large as 200nm.

[0113] In some examples, the depth H1 of the opening 111 may be 70 nm to 100 nm. For example, H1 may be 75 nm, 80 nm, 85 nm, 88 nm, 90 nm, 95 nm, or 98 nm.

[0114] In some embodiments, reference Figure 1 or Figure 3 In a direction Z from the substrate 100 to the gate line 102 , a height H2 of the gate line 102 is 5 μm to 13 μm.

[0115] It is worth noting that the height H2 of the gate line 102 is much higher than the depth H1 of the opening 111. In other words, the height H2 of the gate line 102 is much higher than the thickness of the anti-reflection layer 101. Even so, based on the characteristic that the gate line 102 includes a low-burn-through conductive material, the gate line 102 will not cause excessive erosion to the anti-reflection layer 101 and the substrate 100, which is beneficial to ensure that the thickness of the anti-reflection layer 101 is relatively thin while not causing damage to the anti-reflection layer 101 and the substrate 100, and not causing adverse effects on the photoelectric conversion efficiency of the photovoltaic cell. Moreover, based on the thinning of the thickness of the anti-reflection layer 101, the design of the opening 111 on the anti-reflection layer 101, and the design that the gate line 102 includes a low-burn-through conductive material, it is not only beneficial to reduce the preparation cost of the photovoltaic cell, but also beneficial to improve the photoelectric conversion efficiency of the photovoltaic cell.

[0116] In some examples, the height H2 of the gate line 102 may be 8 μm to 10 μm. For example, H2 may be 8.2 μm, 8.5 μm, 8.8 μm, 9 μm, 9.3 μm, 9.5 μm, or 9.6 μm.

[0117] It should be noted that Figure 3 , Fig.10 and Fig.11 In the examples, the morphology of the first surface 110 is a pyramid morphology. In practical applications, the morphology of the first surface can be designed according to the requirements. In other words, the first surface can be a pyramid morphology or a relatively flat non-pyramid morphology. Figure 4 In the figure, the morphology of the second surface 120 opposite to the first surface 110 along the direction Z is a pyramid morphology as an example. In actual applications, the morphology of the second surface can be designed according to needs. In other words, the second surface can be a pyramid morphology or a relatively flat non-pyramid morphology.

[0118] In summary, the opening 111 of the anti-reflection layer 101 is used to remove the portion of the anti-reflection layer 101 that is directly opposite to the gate line 102, and the low burn-through conductive material has a very weak corrosion and burn-through performance, so that a good ohmic contact is formed between the gate line 102 and the first surface 110, thereby preventing the low burn-through conductive material from further corroding the first surface 110. Moreover, the portion of the gate line 102 located on the surface of the anti-reflection layer 101 away from the substrate 100 can be used to increase the overall cross-sectional area of ​​the gate line 102, so as to reduce the overall resistance of the gate line 102, thereby improving the conductivity of the gate line 102. Moreover, based on the fact that the corrosion and burn-through performance of the low burn-through conductive material is very weak, on the basis of satisfying the performance of the anti-reflection layer 101, the thickness of the anti-reflection layer 101 can be thinned in the direction Z from the substrate 100 to the gate line 102, not only the portion of the gate line 102 located on the surface of the anti-reflection layer 101 away from the substrate 100 will not erode the anti-reflection layer 101, but also the thinning of the anti-reflection layer 101 can reduce the preparation cost of the anti-reflection layer 101, and is also conducive to reducing the parasitic absorption of light by the anti-reflection layer 101, so that more light energy is absorbed by the substrate 100. Therefore, the photovoltaic cell provided in an embodiment of the present disclosure is at least conducive to reducing the preparation cost of the photovoltaic cell while improving the photoelectric conversion efficiency of the photovoltaic cell.

[0119] Another embodiment of the present disclosure further provides a method for preparing a photovoltaic cell, which is used to prepare the photovoltaic cell provided in the above embodiment. The method for preparing a photovoltaic cell provided in another embodiment of the present disclosure will be described in detail below in conjunction with the accompanying drawings. It should be noted that the parts that are the same or corresponding to the above embodiment will not be repeated here.

[0120] Combined with reference Figures 12 to 17 and Figure 2The preparation method of the photovoltaic cell includes the following steps: S101: providing a substrate 100, the substrate 100 having a first surface 110; S102: forming an initial anti-reflection layer 141 covering the first surface 110; S103: removing at least a portion of the thickness of the initial anti-reflection layer 141 along the direction of the substrate 100 pointing to the initial anti-reflection layer 141, that is, in the direction Z, using a laser film opening process to form an initial opening 151 on the initial anti-reflection layer 141, and the remaining initial anti-reflection layer 141 is used as the anti-reflection layer 101; S104: Using a first screen printing process, print a low burn-through type paste in the initial opening 151 and on a portion of the surface of the anti-reflection layer 101 away from the substrate 100; S105: Performing laser-assisted sintering on the low burn-through type paste to transform the low burn-through type paste into a gate line 102 in ohmic contact with the first surface 110, and transform the initial opening 151 into an opening 111, and the orthographic projection of the opening 111 on the substrate 100 is located in the orthographic projection of at least a portion of the gate line 102 on the substrate 100.

[0121] in, Fig.12 A schematic diagram of a partial cross-sectional structure of forming an initial anti-reflection layer in a method for preparing a photovoltaic cell provided in another embodiment of the present disclosure; Fig.13 A schematic diagram of a first partial cross-sectional structure of forming an initial opening in a method for preparing a photovoltaic cell provided in another embodiment of the present disclosure; Fig.14 A schematic diagram of a second partial cross-sectional structure of forming an initial opening in a method for preparing a photovoltaic cell provided in another embodiment of the present disclosure; Fig.15 A schematic diagram of a third partial cross-sectional structure of forming an initial opening in a method for preparing a photovoltaic cell provided in another embodiment of the present disclosure; Fig.16 A schematic diagram of a fourth partial cross-sectional structure of forming an initial opening in a method for preparing a photovoltaic cell provided in another embodiment of the present disclosure; Fig.17 A schematic diagram of a partial top view of the first surface of a substrate in a method for preparing a photovoltaic cell provided in another embodiment of the present disclosure.

[0122] It is worth noting that, since the low-burn-through slurry with lower preparation cost is used to prepare the gate line 102, there is no need for the low-burn-through slurry to penetrate the anti-reflection layer 101 by its own burn-through performance to directly contact the first surface 110. Before preparing the gate line 102, a laser film opening process is used in advance to remove at least a portion of the thickness of the initial anti-reflection layer 141 to form an initial opening 151 on the initial anti-reflection layer 141, thereby facilitating the subsequent direct contact between the gate line 102 and the first surface 110. Further, the low-burn-through slurry is treated by laser assisted sintering to form the gate line 102 in ohmic contact with the first surface 110, wherein the low-burn-through slurry after the laser assisted sintering process makes the gate line 102 include a low-burn-through conductive material.

[0123] Compared with the preparation of the gate line by using the high-burn-through type slurry with higher preparation cost, it is necessary to rely on the burn-through performance of the high-burn-through type slurry itself to penetrate the anti-reflection layer to directly contact with the first surface, and the burn-through degree of the high-burn-through type slurry is difficult to control. There are too many uncertain factors in the contact interface between the high-burn-through type slurry and the anti-reflection layer, and excessive reliance on the burn-through performance of the high-burn-through type slurry and other factors. In another embodiment of the present disclosure, the preparation method provides, on the one hand, a more precise laser film opening process is used to form an initial opening 151 on the initial anti-reflection layer 141, without excessive reliance on The burn-through performance of the low burn-through type slurry, based on the characteristics of the laser film opening process, makes the morphology of the initial opening 151 more controllable, thereby making the morphology of the subsequent opening 111 formed based on the initial opening 151 more controllable; on the other hand, a low burn-through type slurry with a lower preparation cost is used to prepare the gate line 102, and the low burn-through type slurry is processed by laser assisted sintering, so that the low burn-through type slurry is formed in the initial opening 151 without causing excessive erosion to the initial opening 151, and the low burn-through type slurry can be in ohmic contact with the first surface 110.

[0124] Therefore, based on the cooperation of the laser film opening process, the printing of the low-burn-through type slurry and the laser-assisted sintering, firstly, it is helpful to avoid the excessive erosion of the low-burn-through type slurry on the initial anti-reflection layer 141 and the substrate 100; secondly, it is also helpful to make the appearance of the contact interface between the finally formed grid line 102 and the anti-reflection layer 101 more controllable, for example, the side wall 101a of the opening 111 is flat, which is conducive to promoting the formation of a good ohmic contact between the grid line 102 and the first surface 110; thirdly, it is also helpful to reduce the preparation cost of the grid line 102, and to design the thickness of the initial anti-reflection layer 141 to be thinned, so as to further reduce the preparation cost of the anti-reflection layer 101 and reduce the parasitic absorption of light by the anti-reflection layer 101. It can be seen that based on improvements in many aspects, the preparation method provided in another embodiment of the present disclosure is conducive to reducing the preparation cost of photovoltaic cells while improving the photoelectric conversion efficiency of photovoltaic cells.

[0125] The following is a detailed description of each step of the method for preparing a photovoltaic cell:

[0126] In some embodiments, substrate 100 has opposing front and back surfaces.

[0127] In some cases, reference Figure 1 , Figure 12 to Figure 14 The first surface 110 may be a back surface, the base 100 may include a substrate 103 , a tunneling layer 104 and a doped conductive layer 105 stacked in sequence, and the first surface 110 is a surface of the doped conductive layer 105 away from the tunneling layer 104 .

[0128] In other cases, reference Figure 3The first surface 110 may be a front surface, the substrate 100 includes an emitter 106 , and the first surface 110 includes a surface of the emitter 106 .

[0129] In some other cases, reference Figure 4 The first surface 110 may be the back surface, the front surface of the substrate 100 may be regarded as the second surface 120 , and the preparation method may further include performing steps S102 to S105 on the second surface 120 .

[0130] Among them, the anti-reflection layer 101 finally formed on the first surface 110 can be regarded as a back anti-reflection layer, the opening 111 finally formed on the anti-reflection layer 101 can be regarded as a back opening, and the gate line 102 formed in ohmic contact with the first surface 110 can be regarded as a back gate line, and finally a front anti-reflection layer 107 located on the second surface 120 is formed, and the front anti-reflection layer 107 has a front opening 117 exposing the second surface 120, and a front gate line 108 located in the front opening 117 and located on a portion of the surface of the front anti-reflection layer 107 away from the substrate 100, and the orthographic projection of the front opening 117 on the substrate 100 is located in the orthographic projection of at least part of the front gate line 108 on the substrate 100, the material of the front gate line 108 includes a low burn-through conductive material, and the front gate line 108 is in ohmic contact with the second surface 120 exposed by the front opening 117.

[0131] It should be noted that, in practical applications, the first surface may also be the front surface, and the back surface of the substrate may be regarded as the second surface. The preparation method may further include performing steps S102 to S105 on the second surface.

[0132] In some embodiments, in step S102, reference Fig.12 , an initial anti-reflection layer 141 is prepared on the first surface 110 by using a coating process. In practical applications, the preparation method can also prepare a similar initial anti-reflection layer on the second surface.

[0133] In some examples, the coating process includes a chemical vapor deposition process or a physical vapor deposition process, and the coating process uses a process temperature of 200° C. to 600° C. For example, the coating process uses a process temperature of 400° C. to 550° C.

[0134] In some examples, the material of the initial anti-reflection layer 141 includes at least one of silicon nitride, aluminum oxide, silicon oxynitride, or silicon oxide.

[0135] In step S103, the laser film opening process removes at least a portion of the thickness of the initial anti-reflection layer 141, including at least the following two situations:

[0136] In some cases, in conjunction with reference Fig.12 and Fig.13The step of removing at least part of the thickness of the initial anti-reflection layer 141 by the laser film opening process may include: along the direction of the substrate 100 pointing to the initial anti-reflection layer 141, that is, in the direction Z, the laser film opening process removes the entire thickness of the initial anti-reflection layer 141. In other words, the initial opening 151 penetrates the initial anti-reflection layer 141 along the direction Z, and the initial opening 151 exposes part of the first surface 110; based on this, the low burn-through type paste printed in step S104 is in direct contact with the first surface 110 exposed by the initial opening 151, which is convenient for the subsequent laser-assisted sintering process to promote the ohmic contact between the low burn-through type paste and the first surface 110.

[0137] In other cases, combined with reference Fig.12 and Fig.14 The step of removing at least part of the thickness of the initial anti-reflection layer 141 by the laser opening process may include: along the direction of the substrate 100 pointing to the initial anti-reflection layer 141, that is, in the direction Z, the laser opening process removes part of the thickness of the initial anti-reflection layer 141. In other words, the initial opening 151 does not penetrate the initial anti-reflection layer 141 along the direction Z, the initial opening 151 does not expose part of the first surface 110, and the bottom surface of the initial opening 151 is composed of the initial anti-reflection layer 141; based on this, the low burn-through type slurry printed in step S104 needs to be processed by laser-assisted sintering to burn through the initial anti-reflection layer 141 located on the bottom surface of the initial opening 151 to achieve direct contact with the first surface 110.

[0138] It is worth noting that the low burn-through slurry has a weak burn-through performance. When the thickness of the initial anti-reflection layer 141 located at the bottom of the initial opening 151 is very thin, it can be burned through to meet the direct contact between the low burn-through slurry and the first surface 110.

[0139] The specific appearance of the initial opening 151 formed on the initial anti-reflection layer 141 in step S103 is described in detail below. It is worth noting that, except for the depth along the direction Z, the specific morphology of the initial opening 151 is similar to the specific morphology of the opening 111 finally formed, and the parts of the initial opening 151 that are the same as or corresponding to the opening 111 in the aforementioned embodiment will not be repeated here.

[0140] In some embodiments, in conjunction with reference Fig.12 and Fig.15The step of removing at least part of the thickness of the initial anti-reflection layer 141 by a laser film opening process may also include: preparing an initial opening 151 on the initial anti-reflection layer 141 by a continuous point-shaped film opening method along the first direction X. In other words, a plurality of initial openings 151 arranged at intervals along the first direction X are formed on the initial anti-reflection layer 141, and a second spacing D2 is provided between two adjacent initial openings 151 along the first direction X. The ratio of the second length L2 of the initial opening 151 in the first direction X to the second spacing D2 is in the range of 1 / 5 to 10 / 1. For example, the ratio of the two may be 1 / 4, 1 / 3, 1 / 2, 1, 2, 3, 4, 5, 6, 7, 8 or 9, etc.

[0141] Based on this, in step S104 , the initial gate lines formed by printing the low-fire-through paste extend along the first direction X, and one initial gate line is located in the plurality of initial openings 151 .

[0142] It should be noted that Fig.15 In the example, the initial opening 151 penetrates the remaining initial anti-reflection layer along the direction Z. In actual applications, the initial opening may not penetrate the initial anti-reflection layer along the direction. Fig.15 An initial opening 151 is indicated by a dotted line.

[0143] In other embodiments, in combination with reference Fig.12 and Fig.16 The step of removing at least a portion of the thickness of the initial anti-reflection layer 141 by a laser film opening process may also include: preparing an initial opening 151 on the initial anti-reflection layer 141 by a continuous line segment film opening method along the first direction X. In other words, a plurality of initial openings 151 arranged at intervals along the first direction X are formed on the initial anti-reflection layer 141, and a second spacing D2 is provided between two adjacent initial openings 151 along the first direction X. The ratio of the second length L2 of the initial opening 151 in the first direction X to the second spacing D2 is in the range of 1 / 40 to 1 / 5. For example, the ratio of the two may be 1 / 35, 1 / 30, 1 / 25, 1 / 20, 1 / 15, 1 / 10, 1 / 5, 1, 1.5, 2, 2.5, 3, 3.5, 4 or 4.5, etc.

[0144] Based on this, in step S104 , the initial gate lines formed by printing the low-fire-through paste extend along the first direction X, and one initial gate line is located in the plurality of initial openings 151 .

[0145] It should be noted that Fig.16 In the example, the initial opening 151 penetrates the remaining initial anti-reflection layer along the direction Z. In actual applications, the initial opening may not penetrate the initial anti-reflection layer along the direction. Fig.16 An initial opening 151 is indicated by a dotted line.

[0146] In some other embodiments, in combination with reference Fig.12 and Figure 6 The step of removing at least a portion of the thickness of the initial anti-reflection layer 141 by a laser film opening process may further include: forming an initial opening 151 along the first direction X and penetrating the initial anti-reflection layer 141 along the first direction X.

[0147] Based on this, in step S104 , the initial gate lines formed by printing the low-fire-through paste extend along the first direction X, and one initial gate line is located in one initial opening 151 .

[0148] In the above three embodiments, in step S103, the second direction Y is perpendicular to the first direction X, and the width of the initial opening 151 along the second direction Y is the laser film opening line width; in step S104, the width of the low-burn-through type paste printed in the first screen printing process along the second direction Y is the printing line width; wherein the laser film opening line width is less than or equal to the printing line width. In this way, it is beneficial to ensure that the low-burn-through type paste fills the initial opening 151, so as to ensure that the gate line 102 formed in the end has sufficient ohmic contact area with the first surface 110.

[0149] It is worth noting that, combined with reference Fig.13 and Figure 2 ,or Fig.14 and Figure 2 The laser film opening line width determines the width of the initial opening 151 along the second direction Y, and further determines the second width W2 of the final opening 111 (refer to Figure 5 ), so the laser film opening line width is the same as or corresponds to the second width W2 of the opening 111 in the above embodiment, which is not described in detail here; the printing line width determines the first width W1 of the gate line 102 formed in the end (refer to Figure 5 ), so the part where the printed line width is the same as or corresponds to the first width W1 of the gate line 102 in the aforementioned embodiment will not be described in detail here.

[0150] In some embodiments, in step S104, the low burn-through type paste includes copper and silver, and the content of copper in the low burn-through type paste is greater than or equal to the content of silver in the low burn-through type paste. Further, the low burn-through type paste may also include a filler, and the filler mainly includes a glass body or a resin. It is worth noting that the low burn-through type paste is transformed into a gate line 102 including a low burn-through type conductive material after laser-assisted sintering treatment, and the parts of the low burn-through type paste that are the same or corresponding to the low burn-through type conductive material in the aforementioned embodiment are not repeated here.

[0151] In some examples, in the step of printing the low-fire-through paste including copper and silver using the first screen printing process, the printed line width can be 5μm to 50μm, for example, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm or 45μm.

[0152] In some embodiments, after performing step S104 and before performing step S105, the preparation method may further include: performing drying and curing treatments on the low-fire-through type slurry to transform the low-fire-through type slurry into initial gate lines with a stable shape.

[0153] In some examples, in the drying step, the drying temperature used is 100° C. to 400° C. For example, the drying temperature may be 150° C., 200° C., 250° C., 300° C. or 350° C., etc.

[0154] In some examples, in the curing step, the curing temperature used is 150°C to 350°C, for example, the curing temperature can be 180°C, 200°C, 240°C, 250°C, 275°C, 300°C or 320°C, etc.; the curing time is 3min to 30min, for example, the curing time can be 8min, 10min, 15min, 20min, 25min or 28min, etc.

[0155] In some embodiments, reference Fig.13 or Fig.14 In the step of performing the laser film opening process (step S103), the initial opening 151 exposes the first surface 110; after the first screen printing process (step S104), before the laser assisted sintering process (step S105), the contact resistivity between the low burn-through type paste and the first surface 110 is the first resistivity; after the laser assisted sintering process (step S105), refer to Figure 2 The contact resistivity between the low burn-through type slurry and the first surface 110 is the second resistivity, that is, the contact resistivity between the gate line 102 and the first surface 110 is the second resistivity; wherein the second resistivity is less than the first resistivity, and in the step of performing laser assisted sintering, the contact resistivity between the low burn-through type slurry and the first surface 110 is reduced from the first resistivity to the second resistivity.

[0156] It is worth noting that in step S103, forming the initial opening 151 on the initial anti-reflection layer 141 can be regarded as replacing the step of using the high burn-through type slurry to penetrate the anti-reflection layer by its burn-through performance, so that before the low burn-through type slurry is subjected to laser-assisted sintering, the low burn-through type slurry can achieve direct contact with the first surface 110, further ensuring that the low burn-through type slurry can achieve good ohmic contact with the first surface 110 during the laser-assisted sintering step. In the laser-assisted sintering step, the local current generated in the photovoltaic cell will significantly reduce the contact resistivity between the grid line 102 and the first surface 110, that is, the contact resistivity between the low burn-through type slurry and the first surface 110 is reduced from the first resistivity to the second resistivity, thereby facilitating the improvement of the photoelectric conversion efficiency of the photovoltaic cell.

[0157] In some examples, the first resistivity is greater than 10 mΩ·cm 2 , the second resistivity is less than 5mΩ·cm 2 .

[0158] In some examples, the step of performing laser-assisted sintering on the low burn-through paste may include using at least one of infrared light, red light, and green light as a processing light source, scanning the photovoltaic cell with the processing light source, and at the same time, applying a reverse bias voltage to the gate line 102 .

[0159] In one example, the reverse bias voltage may be 10V to 20V.

[0160] In one example, the step of scanning the photovoltaic cell using the processing light source may include: scanning the surface of the photovoltaic cell where the grid line 102 is located using the processing light source.

[0161] In some embodiments, the laser-assisted sintering process includes at least one laser-assisted sintering process.

[0162] It is worth noting that if the contact resistivity between the gate line 102 and the first surface 110 is not low enough after one laser-assisted sintering process, the gate line 102 may be subjected to a second or even a third laser-assisted sintering process to make the contact resistivity between the gate line 102 and the first surface 110 meet the expected requirements. Therefore, in practical applications, the number of times the laser-assisted sintering process is performed in the laser-assisted sintering process may be designed according to demand.

[0163] In some examples, if the laser-assisted sintering process includes more than one laser-assisted sintering process, the processing light source can scan different sides of the photovoltaic cell in different laser-assisted sintering processes, for example, in some laser-assisted sintering processes, the processing light source scans the side of the photovoltaic cell where the grid line 102 is located, and in other laser-assisted sintering processes, the processing light source scans the other side of the photovoltaic cell opposite to the side where the grid line 102 is located. In other words, both the front and back sides of the photovoltaic cell are scanned by the processing light source.

[0164] In practical applications, in different laser-assisted sintering processes, the processing light source can also scan the front side of the photovoltaic cell or the back side of the photovoltaic cell.

[0165] It is worth noting that the gate line 102 formed in step S105 and in ohmic contact with the first surface 110 can be a main gate, a fine gate, or a main gate and a fine gate. The following describes in detail the preparation process of the gate line 102 in various situations.

[0166] In some embodiments, reference Fig.17 , the first surface 110 may include a first area 140 and a second area 150, the first area 140 extends along the second direction Y, the second area 150 extends along the first direction X, and the first direction X and the second direction Y intersect; in conjunction with reference Fig.17 and Fig.13 ,or Fig.17 and Fig.14 , a laser film opening process is used to remove at least a portion of the thickness of the initial anti-reflection layer 141 (reference Fig.12 ) step (step S103) may include: removing at least part of the thickness of the initial anti-reflection layer 141 located on the second zone 150; before printing the low burn-through type paste (step S104), the preparation method may also include: using a second screen printing process to print the burn-through type paste on the initial anti-reflection layer 141 located in the first zone 140.

[0167] It should be noted that, in order to clearly illustrate the approximate positions of the first area 140 and the second area 150 on the first surface 110, Fig.17 In the figure, the first area 140 is indicated by a relatively sparse dashed line frame, and the second area 150 is indicated by a relatively dense dashed line frame.

[0168] It is worth noting that the burn-through paste printed by the second screen printing process is different from the low burn-through paste printed by the first screen printing process. The burn-through paste printed by the second screen printing process has a stronger ability to burn through the initial anti-reflective layer 141. For example, the burn-through paste printed by the second screen printing process can be the high burn-through paste described in the aforementioned embodiment.

[0169] It should be noted that the first surface 110 includes a main gate and a secondary gate, the first region 140 is in ohmic contact with the main gate formed subsequently, and the second region 150 is in ohmic contact with the secondary gate formed subsequently. The gate line 102 formed in step S104 can be regarded as the secondary gate on the first surface 110.

[0170] In some cases, after printing the fire-through paste and before printing the low fire-through paste (step S104), the preparation method may further include: performing a high-temperature sintering treatment on the fire-through paste so that the fire-through paste penetrates the initial anti-reflection layer 141 along the direction Z to make ohmic contact with the first region 140.

[0171] In some examples, process parameters for high temperature sintering of the burn-through slurry may include: a high temperature sintering temperature of about 400° C. to 700° C.; a light annealing temperature of about 200° C. to 400° C.; and a light intensity equivalent to 1 to 30 suns.

[0172] It is worth noting that when the main grid on the first surface 110 is prepared by a burn-through type slurry, and the auxiliary grid is prepared by a low burn-through type slurry, a laser film opening process is first performed to remove the initial anti-reflection layer 141 of the area on the first surface 110 that needs to be in contact with the auxiliary grid, that is, the second area 150, so as to form an initial opening 151 that facilitates the low burn-through type slurry to form an ohmic contact with the second area 150, and then the second screen printing process is first used to prepare the main grid, and then the first screen printing process is used to prepare the grid line 102, that is, the auxiliary grid based on the initial opening 151. In this way, the laser film opening process is advanced to the preparation of the main grid and the auxiliary grid, which is conducive to avoiding laser damage to the already formed main grid when the laser film opening process is performed after the main grid is formed, thereby avoiding adverse effects on the photoelectric conversion efficiency of the photovoltaic cell.

[0173] In some other embodiments, continue to refer to Fig.17 , the first surface 110 may include a first area 140 and a second area 150, the first area 140 extends along the second direction Y, the second area 150 extends along the first direction X, and the first direction X and the second direction Y intersect; in conjunction with reference Fig.17 and Fig.13 ,or Fig.17 and Fig.14 The step of removing at least a portion of the thickness of the initial anti-reflection layer 141 by a laser film opening process (step S103) may include: removing at least a portion of the thickness of the initial anti-reflection layer 141 located on the first area 140 and the second area 150.

[0174] It should be noted that the first surface 110 includes a main gate and a sub-gate, the first region 140 is in ohmic contact with the main gate formed subsequently, and the second region 150 is in ohmic contact with the sub-gate formed subsequently. The gate line 102 formed in step S104 can be regarded as the main gate and the sub-gate on the first surface 110.

[0175] In some other embodiments, reference Figure 4 The substrate 100 also includes a second surface 120 opposite to the first surface 110 along the direction Z. One of the first surface 110 and the second surface 120 is the front side of the substrate 100, and the other is the back side of the substrate 100. The following is a detailed description taking the first surface 110 as the back side of the substrate as an example.

[0176] In some cases, reference Figure 4 , steps S102 to S105 are performed on the second surface 120, and finally a front anti-reflection layer 107 having a front opening 117 exposing the second surface 120 and a front grid line 108 located in the front opening 117 and located on a portion of the surface of the front anti-reflection layer 107 away from the substrate 100 is formed. It should be noted that, like the grid line 102 located on the first surface 110 described in the aforementioned embodiment, the front grid line 108 includes a main grid, a sub-grid, or a main grid and a sub-grid.

[0177] In other cases, combined with reference Fig.17 and Fig.12 In the step of printing the burn-through paste on the initial anti-reflection layer 141 located in the first area 140 by using the second screen printing process, the burn-through paste is also printed on the second surface 120 to form the gate lines located on the second surface; the step of performing high-temperature sintering treatment on the burn-through paste also includes performing high-temperature sintering treatment on the burn-through paste printed on the second surface 120.

[0178] It should be noted that, whether it is the first surface 110 or the second surface 120, if a low burn-through type paste is used to prepare the gate line that is in ohmic contact with the surface, steps S103 to S105 need to be performed; if a burn-through type paste is used to prepare the gate line that is in ohmic contact with the surface, a second screen printing process is required to print the burn-through type paste and sinter the burn-through type paste at high temperature.

[0179] In summary, based on the cooperation of the laser film opening process, the printing of the low-burn-through slurry and the laser-assisted sintering, firstly, it is conducive to avoiding the excessive erosion of the initial anti-reflection layer 141 and the substrate 100 by the low-burn-through slurry; secondly, it is also conducive to making the appearance of the contact interface between the finally formed grid line 102 and the anti-reflection layer 101 more controllable, for example, the side wall 101a of the opening 111 is flat, which is conducive to promoting the formation of a good ohmic contact between the grid line 102 and the first surface 110; thirdly, it is also conducive to reducing the preparation cost of the grid line 102, and thinning the thickness of the initial anti-reflection layer 141 to further reduce the preparation cost of the anti-reflection layer 101 and reduce the parasitic absorption of light by the anti-reflection layer 101. Based on improvements in many aspects, the preparation method provided in another embodiment of the present disclosure is conducive to reducing the preparation cost of photovoltaic cells while improving the photoelectric conversion efficiency of photovoltaic cells.

[0180] Another embodiment of the present disclosure further provides a photovoltaic module, which is used to convert received light energy into electrical energy. The photovoltaic module provided by another embodiment of the present disclosure will be described in detail below in conjunction with the accompanying drawings. It should be noted that the parts that are the same or corresponding to the above embodiments are not repeated here.

[0181] Fig.18 A schematic diagram of a partial three-dimensional structure of a photovoltaic assembly provided by another embodiment of the present disclosure; Fig.19 for Fig.18 Schematic diagram of a local cross-sectional structure along the M1-M2 section.

[0182] Combined with reference Fig.18 and Fig.19 The photovoltaic module includes: a battery string, which is formed by connecting multiple photovoltaic cells 109 provided in the above-mentioned embodiments, or by connecting multiple photovoltaic cells 109 formed by the preparation method provided in the above-mentioned embodiments; a packaging film 119, which is used to cover the surface of the battery string; and a cover plate 129, which is used to cover the surface of the packaging film 119 away from the battery string.

[0183] In some embodiments, reference Fig.19 , multiple battery strings can be electrically connected through welding strips 139. Fig.19 Only one positional relationship between photovoltaic cells is illustrated, that is, the arrangement direction of the electrodes with the same polarity of the cells is the same, or the electrodes with positive polarity of each cell are arranged toward the same side, so that the welding strip 139 connects different sides of two adjacent cells respectively. In some embodiments, the cells can also be arranged in the order of electrodes with different polarities facing the same side, that is, the electrodes of multiple adjacent cells are arranged in the order of the first polarity, the second polarity, and the first polarity, and then the welding strip connects two adjacent cells on the same side.

[0184] In some embodiments, no intervals are set between the battery cells, that is, the battery cells overlap each other.

[0185] In some embodiments, reference Fig.19 The encapsulation film 119 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 photovoltaic cell 109, and the second encapsulation layer covers the other of the front side or the back side of the photovoltaic cell 109. 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.

[0186] In some cases, there is a boundary line between the first encapsulation layer and the second encapsulation layer before lamination. After the lamination process, the photovoltaic module is formed and there is no longer the concept of the first encapsulation layer and the second encapsulation layer, that is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film 119.

[0187] In some embodiments, reference Fig.19 The cover plate 129 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 129 facing the encapsulation film 119 may be a concave-convex surface, thereby increasing the utilization rate of the incident light. The cover plate 129 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.

[0188] In some embodiments, the photovoltaic cell 109 includes, but is not limited to, one or any combination of PERC cells (Passivated EmitterRear Cell), IBC cells (Interdigitated Back Contact), TOPCon cells (Tunnel Oxide Passivated Contact), HIT / HJT cells (Heterojunction Technology heterojunction cells), solar thin-film cells, and stacked cells. Among them, solar thin-film cells include, but are not limited to, perovskite solar thin-film cells, copper indium selenide solar thin-film cells, gallium arsenide solar thin-film cells, and cadmium sulfide solar thin-film cells. Stacked cells include, but are not limited to, perovskite cells superimposed on crystalline silicon cells, perovskite cells superimposed on perovskite cells, and perovskite cells superimposed on thin-film cells.

[0189] Those skilled in the art can understand that the above-mentioned embodiments are specific examples for implementing the present disclosure, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of the embodiments of the present disclosure. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of the present disclosure, so the protection scope of the embodiments of the present disclosure shall be based on the scope defined in the claims.

Claims

1. A photovoltaic cell, characterized in that: include: a substrate having a first surface; an anti-reflection layer, located on the first surface, and having an opening exposing the first surface; A grid line is located in the opening and on a portion of the surface of the anti-reflection layer away from the substrate, and an orthographic projection of the opening on the substrate is located in an orthographic projection of at least a portion of the grid line on the substrate; The material of the gate line includes a low-burn-through conductive material, and the gate line is in ohmic contact with the first surface exposed by the opening.

2. The photovoltaic cell according to claim 1, characterized in that: The low fire-through type conductive material includes copper and silver, and a content of the copper in the low fire-through type conductive material is greater than or equal to a content of the silver in the low fire-through type conductive material.

3. The photovoltaic cell according to claim 1, characterized in that: The anti-reflection layer has a side wall constituting the opening, and the plane where the first surface is located is used as a reference plane, and the angle between the side wall and the reference plane is 45° to 150°; and / or the surface roughness of the side wall is less than or equal to 6.3 μm; and / or the gate line covers the side wall; and / or the contact resistivity between the gate line and the first surface is less than 5 mΩ·cm 2 .

4. The photovoltaic cell according to any one of claims 1 to 3, characterized in that The gate line extends along a first direction, a second direction is perpendicular to the first direction, and along the second direction, a first width of the gate line is greater than or equal to a second width of the opening.

5. The photovoltaic cell according to any one of claims 1 to 3, characterized in that: The gate line extends along a first direction, and the gate line has two ends along the first direction, and a middle portion connecting the two ends; in a direction along the substrate pointing to the gate line, a region in the opening corresponding to the end is a first sub-opening, and a region in the opening corresponding to the middle portion is a second sub-opening; The second direction is perpendicular to the first direction, and along the second direction, the first sub-width of the end portion is greater than or equal to the second sub-width of the middle portion; and / or the third sub-width of the first sub-opening is greater than or equal to the fourth sub-width of the second sub-opening.

6. The photovoltaic cell according to any one of claims 1 to 3, characterized in that: An ohmic contact interface is provided between the gate line and the first surface, the gate line comprises silver microcrystals in contact with the ohmic contact interface, the ohmic contact interface comprises a first region in contact with the silver microcrystals, and the ratio of the area of ​​the first region to the area of ​​the ohmic contact interface is in a range of 60% to 90%.

7. A method for preparing a photovoltaic cell, characterized in that: include: providing a substrate having a first surface; forming an initial anti-reflection layer covering the first surface; Along the direction from the substrate to the initial anti-reflection layer, using a laser film opening process to remove at least a portion of the thickness of the initial anti-reflection layer to form an initial opening on the initial anti-reflection layer, and the remaining initial anti-reflection layer serves as the anti-reflection layer; Using a first screen printing process, printing a low-burn-through paste in the initial opening and on a portion of the surface of the anti-reflection layer away from the substrate; The low-burn-through paste is subjected to laser-assisted sintering to transform the low-burn-through paste into a gate line in ohmic contact with the first surface, and to transform the initial opening into an opening whose orthographic projection on the substrate is located in the orthographic projection of at least part of the gate line on the substrate.

8. The preparation method according to claim 7, characterized in that: In the step of performing the laser film opening process, the initial opening exposes the first surface; after performing the first screen printing process and before performing the laser assisted sintering process, the contact resistivity between the low burn-through type paste and the first surface is a first resistivity; after performing the laser assisted sintering process, the contact resistivity between the low burn-through type paste and the first surface is a second resistivity; The second resistivity is smaller than the first resistivity, and in the step of performing the laser assisted sintering process, the contact resistivity between the low burn-through slurry and the first surface is reduced from the first resistivity to the second resistivity.

9. The preparation method according to claim 7, characterized in that: The first surface includes a first area and a second area, the first area extends along the second direction, the first area extends along the first direction, and the first direction and the second direction intersect; The step of removing at least a portion of the thickness of the initial anti-reflection layer by the laser film opening process includes: removing at least a portion of the thickness of the initial anti-reflection layer located on the second area; Before printing the low burn-through type paste, the preparation method further comprises: using a second screen printing process to print the burn-through type paste on the initial anti-reflection layer located in the first area.

10. A photovoltaic module, characterized in that: include: A battery string, formed by connecting a plurality of photovoltaic cells according to any one of claims 1 to 6, or formed by connecting a plurality of photovoltaic cells formed by the preparation method according to any one of claims 7 to 9; 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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