Solar cell and method for manufacturing solar cell

Abstract

A solar cell and a method for manufacturing a solar cell, relating to the technical field of solar cells, for solving the problem that a bus electrode made of metal is completely and directly in contact with a semiconductor substrate, resulting in high metal recombination on a surface of the solar cell and reduction in the cell efficiency of the solar cell. The solar cell comprises: a semiconductor substrate, first conductive contact layers, bus electrodes, and collector electrodes. The first conductive contact layers are formed on at least one surface of the semiconductor substrate. The plurality of first conductive contact layers extend in a first direction and are spaced apart along a second direction. The bus electrodes are formed on the first conductive contact layers and are located on at least one surface of the semiconductor substrate. The plurality of bus electrodes extend in the first direction and are spaced apart along the second direction. The projection of at least some of the first conductive contact layers on the semiconductor substrate is overlapped with the projection of the bus electrodes on the semiconductor substrate. The first direction is different from the second direction.

Description

Solar cell and method for manufacturing solar cell

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent applications filed with the China Patent Office on September 12, 2023, with application numbers 202311175882.0 and 202410711099.X, entitled “A Solar Cell and a Method for Manufacturing a Solar Cell”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the technical field of solar cells, and in particular to a solar cell and a method for manufacturing the solar cell. Background Art

[0004] A solar cell is a device that utilizes solar energy, directly converting light energy into electrical energy through the photoelectric effect or photochemical effect. A solar cell generally consists of a semiconductor substrate, a collector electrode, and a busbar electrode, which are typically made of metal.

[0005] In the related art, the busbar electrode made of metal is in direct contact with the semiconductor substrate, which results in a high metal composite on the surface of the solar cell, thereby reducing the cell efficiency of the solar cell.

[0006] Summary of the Invention

[0007] The purpose of the present application is to provide a solar cell and a method for manufacturing the solar cell, which are used to reduce or eliminate metal recombination on the surface of the solar cell, so as to improve the cell efficiency of the solar cell.

[0008] In order to achieve the above-mentioned objectives, in a first aspect, the present application provides a solar cell. The solar cell includes: a semiconductor substrate, a first conductive contact layer, a bus electrode, and a collector electrode. The semiconductor substrate has a first surface and a second surface opposite to each other. The first conductive contact layer is formed on at least one side of the semiconductor substrate, and a plurality of first conductive contact layers extend along a first direction and are spaced apart along a second direction. The bus electrode is located on at least one side of the semiconductor substrate; the bus electrode is formed above the first conductive contact layer; the plurality of bus electrodes extend along the first direction and are spaced apart along the second direction. The projection of at least part of the first conductive contact layer on the semiconductor substrate overlaps with the projection of the bus electrode on the semiconductor substrate, and the first direction is different from the second direction. The plurality of collector electrodes extend along the second direction and are spaced apart along the first direction, and each bus electrode intersects with the plurality of collector electrodes.

[0009] In the solar cell provided by this application, because at least a portion of the projection of the first conductive contact layer on the semiconductor substrate overlaps with the projection of the bus electrode on the semiconductor substrate, the bus electrode and the semiconductor substrate are partially in direct contact or completely out of contact. Based on this, compared to related technologies, metal recombination on the surface of the solar cell can be reduced or eliminated, increasing the open-circuit voltage of the solar cell and thereby improving the cell efficiency of the solar cell.

[0010] In one implementation, the solar cell further includes a second conductive contact layer. Multiple strips of the second conductive contact layer extend along the second direction and are spaced apart along the first direction. A projection of a collector electrode located on at least one side of the semiconductor substrate overlaps with a projection of the second conductive contact layer on the semiconductor substrate. Each strip of the first conductive contact layer intersects with the multiple strips of the second conductive contact layer.

[0011] When the above technical solution is adopted, combined with the previous description, since the solar cell includes a first conductive contact layer and a second conductive contact layer, this can not only reduce the contact resistivity and the series resistance to effectively collect current and improve the battery efficiency of the solar cell; at the same time, it can also reduce the transmission distance of the carriers to reduce the recombination loss of the carriers during the transmission process.

[0012] In one implementation, the number of the first conductive contact layers located between any two adjacent bus electrodes is greater than or equal to one.

[0013] When using this technical solution, since the first conductive contact layer is also present between any two adjacent bus electrodes, the carrier transmission distance can be further reduced, thereby further reducing carrier recombination losses during transmission. Specifically, during transmission, carriers are recombined with impurity defects during transmission, thus shortening the transmission distance and reducing carrier recombination losses.

[0014] In one implementation, the width of the first conductive contact layer between any two adjacent bus electrodes is greater than or equal to 10 micrometers and less than or equal to 150 micrometers, and the width direction of the first conductive contact layer is consistent with the second direction.

[0015] The above technical solution not only reduces the shielding of the semiconductor substrate by the first conductive contact layer, thereby reducing the impact on the semiconductor substrate's light absorption and improving the efficiency of the solar cell, but also enhances the passivation effect on the solar cell. Furthermore, it can also reduce the current transmission distance, thereby reducing current losses.

[0016] In one implementation, the width of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate is greater than or equal to 50 micrometers and less than or equal to 300 micrometers, and the width direction of the first conductive contact layer is consistent with the second direction.

[0017] When the above technical solution is adopted, the influence of the material for making the bus electrode on the size of the surface area of ​​the semiconductor substrate can be reduced, or the influence of the material for making the bus electrode on the surface of the semiconductor substrate can be avoided. Furthermore, in addition to the role of passivating the surface, the first conductive contact layer also needs to play the role of collecting the current collected by the collector electrode. Since the metal used in the solar cell in this application is generally a metal paste, the metal material used is mostly metal powder. The metal powder has a certain particle size, so it is easy to corrode downward when forming a metal semiconductor alloy. Based on this, the first conductive contact layer needs to have a certain thickness to prevent the metal from burning through the first conductive contact layer and directly contacting the semiconductor substrate. Therefore, the first conductive contact layer that overlaps with the projection of the bus electrode on the semiconductor substrate needs to have a certain thickness to play a blocking role to reduce metal recombination. In addition, the main function of the first conductive contact layer other than the first conductive contact layer directly below the bus electrode is to assist the second conductive contact layer in collecting current, reduce the transmission distance of the carrier, and thus reduce the recombination loss. However, since the parasitic absorption of the first conductive contact layer is strong (that is, when light passes through the first conductive contact layer, most of the light energy is absorbed by the first conductive contact layer, and no large number of photogenerated carriers are generated at the PN junction, the ineffective absorption is large, resulting in current loss), the thicker the first conductive contact layer, the lower the current. Furthermore, when the width of the first conductive contact layer is less than 50 μm, it is easily removed during the cleaning process. When the width of the first conductive contact layer is less than the width of the bus electrode, the first conductive contact layer cannot effectively collect current. When the first conductive contact layer is an incomplete structure, it not only cannot play an auxiliary transmission role, but will affect surface passivation. Furthermore, if the width of the first conductive contact layer is too wide, it will severely block light, causing the current to drop.

[0018] In one implementation, the length of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate is less than the length of the semiconductor substrate and greater than the length of the bus electrode. The width of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate is greater than the width of the bus electrode.

[0019] When the above technical solution is adopted, the bus electrode is reduced or avoided from being in direct contact with the semiconductor substrate in terms of both length and width, so as to reduce or eliminate metal recombination on the surface of the solar cell, increase the open circuit voltage of the solar cell, and thus improve the cell efficiency of the solar cell.

[0020] In one implementation, the length of the first conductive contact layer located between any two adjacent bus electrodes is less than or equal to the length of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate; and / or the width of the first conductive contact layer located between any two adjacent bus electrodes is less than or equal to the width of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate; and / or the thickness of the first conductive contact layer located between any two adjacent bus electrodes is less than or equal to the thickness of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate.

[0021] When using the above technical solution, the entire current collection process for the entire solar cell is as follows: light shines on the solar cell surface, generating a large number of photogenerated carriers at the PN junction within the cell. Under the action of the built-in electric field, the photogenerated carriers are separated to the surface through the P and N regions or doped regions. The first conductive contact region at the surface, which forms a metal contact with the doped region, collects all unrecombined carriers that converge on the surface of the semiconductor substrate. Therefore, to better collect current, the first conductive contact region should cover the entire semiconductor substrate surface as much as possible, so the first conductive contact layer should be relatively long. However, light shines above the first conductive contact layer, and the first conductive contact layer has strong parasitic absorption, that is, strong ineffective absorption. Considering this, the first conductive contact layer at the busbars needs to be wider and thicker to prevent the metal from etching downward toward the edge of the semiconductor substrate. The length, width, and thickness of the first conductive contact layer between the busbars should be smaller than those of the first conductive contact layer in other areas.

[0022] Because the first conductive contact layer located between any two adjacent bus electrodes serves to transmit current, there is no need to prevent the bus electrodes from being in complete direct contact with the semiconductor substrate. Therefore, the first conductive contact layer located between any two adjacent bus electrodes can be smaller in length, width, and thickness than the first conductive contact layer that overlaps the projection of the bus electrodes on the semiconductor substrate, thereby saving manufacturing materials and reducing costs.

[0023] In one implementation, the thickness of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate is greater than or equal to 30 nanometers and less than or equal to 600 nanometers, and the thickness direction of the first conductive contact layer is consistent with the direction from the first surface to the second surface of the semiconductor substrate.

[0024] When the above technical solution is adopted, the thickness of the first conductive contact layer is greater than or equal to 30 nanometers, which can reduce or eliminate the probability of the material used to make the busbar electrode burning through the semiconductor substrate, thereby reducing or eliminating metal recombination on the surface of the solar cell, thereby improving the cell efficiency of the solar cell. Furthermore, due to the strong parasitic absorption of the first conductive contact layer (i.e., when light passes through the first conductive contact layer, most of the light energy is absorbed by the first conductive layer, and no large number of photogenerated carriers are generated at the PN junction, resulting in large ineffective absorption and current loss), a thicker first conductive contact layer will lead to a decrease in current. Therefore, the thickness of the first conductive contact layer needs to be less than or equal to 600 nanometers.

[0025] In one implementation, a ratio of an area of ​​the first conductive contact layer overlapping with a projection of the bus electrode on the semiconductor substrate to a sum of areas of the first conductive contact layer and the second conductive contact layer is greater than or equal to 0.1% and less than or equal to 5%.

[0026] In theory, the optimal solution using the above technical solution is for the busbar electrode to completely cover the first conductive contact layer, which overlaps with the projection of the busbar electrode on the semiconductor substrate. However, in actual production, with the exception of a few relatively costly and less mature metallization processes, such as electroplating and vapor deposition, conventional metallization solutions cannot achieve complete coverage. Therefore, in existing overprinting scenarios, the optimal cell efficiency is achieved within the above range.

[0027] In one implementation, a ratio of an area of ​​the first conductive contact layer between two adjacent bus electrodes to an area of ​​the first conductive contact layer overlapping with a projection of the bus electrode on the semiconductor substrate is greater than or equal to 5% and less than or equal to 20%.

[0028] When adopting the above technical solution, the passivation effect, parasitic absorption, current collection and gold-semiconductor contact are comprehensively considered. Within the above range, the passivation effect is optimal, the parasitic absorption is small, the current collection is more, the contact between the metal and semiconductor substrate is good, and the metal composite is small, thereby obtaining the best battery efficiency.

[0029] In one implementation, the ratio of the sum of the areas of the first conductive contact layer and the second conductive contact layer formed on the first surface of the semiconductor substrate to the area of ​​the first surface of the semiconductor substrate is greater than or equal to 5% and less than or equal to 15%; and / or the ratio of the sum of the areas of the first conductive contact layer and the second conductive contact layer formed on the second surface of the semiconductor substrate to the area of ​​the second surface of the semiconductor substrate is greater than or equal to 5% and less than or equal to 15%.

[0030] When adopting the above technical solution, on the one hand, the conductive contact layer cannot block too much of the solar cell as a whole. Excessive blocking area will reduce the solar cell's absorption of light and the generation of photogenerated carriers. On the other hand, the photogenerated carriers generated by the entire solar cell need to be collected. Considering the efficiency of photogenerated carrier collection, the conductive contact layer should cover the entire surface as much as possible. However, considering the disadvantages of light blocking caused by the conductive contact layer, it cannot completely block the entire surface. Taking all these aspects into consideration, the first and second conductive contact layers are connected in a mesh shape, which not only avoids excessive blocking but also ensures current collection. In addition, the good passivation effect of the first and second conductive contact layers will enhance the passivation effect of the entire solar cell. However, too small an area will result in a longer current collection path, a larger series connection, and increased recombination losses. Higher doping concentrations in the first and second conductive contact layers are conducive to forming a good metal-semiconductor contact, while lower doping concentrations are conducive to reducing recombination. Therefore, it is necessary to comprehensively consider the area ratio and doping concentration to balance the open-circuit voltage, short-circuit current, and fill factor of the solar cell to form a cell structure with higher efficiency.

[0031] In a second aspect, the present application also provides a method for manufacturing a solar cell.

[0032] The manufacturing method of the solar cell comprises:

[0033] First, a semiconductor substrate is provided; the semiconductor substrate has a first surface and a second surface opposite to each other;

[0034] Next, forming a first conductive contact layer extending along the first direction and spaced apart along the second direction on at least one surface of the semiconductor substrate;

[0035] Next, a plurality of bus electrodes extending along a first direction and spaced apart along a second direction are formed on the first conductive contact layer; the bus electrodes are located on at least one side of the semiconductor substrate; at least a portion of the projection of the first conductive contact layer on the semiconductor substrate overlaps with the projection of the bus electrodes on the semiconductor substrate, and the first direction is different from the second direction. A plurality of collector electrodes extending along the second direction and spaced apart along the first direction are formed; each bus electrode intersects with the plurality of collector electrodes.

[0036] In the solar cell manufactured using the solar cell manufacturing method provided in this application, because the projection of at least a portion of the first conductive contact layer on the semiconductor substrate overlaps with the projection of the bus electrode on the semiconductor substrate, the bus electrode and the semiconductor substrate are partially in direct contact or completely out of contact. Based on this, compared to related technologies, metal recombination on the solar cell surface can be reduced or eliminated, increasing the open-circuit voltage of the solar cell and thereby improving the cell efficiency of the solar cell.

[0037] In one implementation, a plurality of second conductive contact layers extending along a second direction and spaced apart along a first direction are formed on at least one surface of a semiconductor substrate. The projection of a collector electrode located on at least one surface of the semiconductor substrate overlaps with the projection of the second conductive contact layer on the semiconductor substrate, and each first conductive contact layer intersects with the plurality of second conductive contact layers.

[0038] In one implementation, the number of the first conductive contact layers located between any two adjacent bus electrodes is greater than or equal to one.

[0039] In one implementation, the length of the first conductive contact layer located between any two adjacent bus electrodes is less than or equal to the length of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate; and / or the width of the first conductive contact layer located between any two adjacent bus electrodes is less than or equal to the width of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate; and / or the thickness of the first conductive contact layer located between any two adjacent bus electrodes is less than or equal to the thickness of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0041] FIG1 is a schematic structural diagram of a first conductive contact layer and a second conductive contact layer in an embodiment of the present application;

[0042] FIG2 is a schematic structural diagram of a collector electrode, a first conductive contact layer, and a second conductive contact layer in an embodiment of the present application;

[0043] FIG3 is a schematic structural diagram of a bus electrode, a collector electrode, a first conductive contact layer, and a second conductive contact layer in an embodiment of the present application;

[0044] FIG4 is a schematic structural diagram of a solar cell in an embodiment of the present application;

[0045] FIG5 is a schematic diagram of a series resistor of a solar cell in the related art;

[0046] FIG6 is a schematic diagram of the series resistance of a solar cell in an embodiment of the present application;

[0047] FIG7 is a schematic diagram of current flow when only the second conductive contact layer is provided in an embodiment of the present application;

[0048] FIG8 is a schematic diagram of current flow when a first conductive contact layer and a second conductive contact layer are provided in an embodiment of the present application;

[0049] FIG9 is a graph showing the relationship between the number of first conductive contact layers and the second conductive contact layer and the improvement in battery efficiency in an embodiment of the present application;

[0050] FIG10 is a diagram showing the relationship between the width of the fourth conductive contact layer and the fill factor improvement value, the battery efficiency improvement value, and the current loss improvement value in an embodiment of the present application;

[0051] FIG11 is a diagram showing the relationship between the width of the third conductive contact layer and the fill factor improvement value, the battery efficiency improvement value, and the open circuit voltage improvement value in an embodiment of the present application.

[0052] Reference numerals: 1 - first conductive contact layer, 10 - third conductive contact layer, 11 - fourth conductive contact layer, 2 - bus electrode, 3 - collecting electrode, 4 - second conductive contact layer, 5 - semiconductor substrate, 6 - contact conductive region. DETAILED DESCRIPTION

[0053] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0054] It should be noted that when an element is referred to as being “fixed” or “disposed” on another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected” to another element, it may be directly connected to the other element or indirectly connected to the other element.

[0055] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "multiple" means two or more, unless otherwise clearly and specifically defined. "Several" means one or more, unless otherwise clearly and specifically defined.

[0056] In the description of this application, it should be understood that the terms "up", "down", "front", "back", "left", "right", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on this application.

[0057] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0058] In conjunction with the background technology section, for solar cells, in order to reduce the series resistance and effectively collect current, the pattern of the collector electrode is usually optimized. For example, the number of collector electrodes is increased in a targeted manner, or a small horizontal line is added between the two collector electrodes. The small horizontal line is usually called a drain line, or an anti-break grid line. However, whether it is increasing the number of collector electrodes or adding drain lines, it will essentially increase the shielding area of ​​the semiconductor substrate surface, thereby reducing the absorption of light by the semiconductor substrate surface and reducing the current. Moreover, the more the number of collector electrodes or drain lines is increased, the larger the shielding area, the less light is absorbed, the lower the current, and the battery efficiency may also be reduced.

[0059] In order to solve the above technical problems, in the first aspect, the embodiments of the present application provide a solar cell. Referring to Figures 1 to 3, the solar cell includes: a semiconductor substrate, a first conductive contact layer 1, a bus electrode 2, and a collector electrode 3. The semiconductor substrate has a first surface and a second surface opposite to each other. The first conductive contact layer 1 is formed on at least one surface of the semiconductor substrate. A plurality of first conductive contact layers 1 extend along a first direction A and are spaced apart along a second direction B. The bus electrode 2 is located on at least one surface of the semiconductor substrate. The bus electrode 2 is formed above the first conductive contact layer 1. A plurality of bus electrodes 2 extend along the first direction A and are spaced apart along a second direction B. The projection of at least part of the first conductive contact layer 1 on the semiconductor substrate overlaps with the projection of the bus electrode 2 on the semiconductor substrate. The first direction A is different from the second direction B. A plurality of collector electrodes 3 extend along the second direction and are spaced apart along the first direction. Each bus electrode intersects with a plurality of collector electrodes.

[0060] In this article, the "bus electrode" is a structure used for current collection that intersects with the collecting electrode. It can be a main grid electrode that intersects with the collecting electrode, and the main grid electrode plays the role of collecting current; it can also be a bus bar or interconnect bar that intersects with the collecting electrode, such as a welding strip, a wire, etc., which is used to replace the main grid electrode and plays the role of collecting current.

[0061] In the solar cell provided in the embodiments of the present application, because at least a portion of the projection of the first conductive contact layer 1 on the semiconductor substrate overlaps with the projection of the bus electrode 2 on the semiconductor substrate, the bus electrode 2 may be partially in direct contact with the semiconductor substrate or completely out of contact with the semiconductor substrate. From the perspective of the cell structure, partial direct contact and partial non-contact between the bus electrode and the cell body are achieved by locally providing the first conductive contact layer between the bus electrode and the cell body; complete non-contact between the bus electrode and the cell body is achieved by providing the first conductive contact layer entirely between the bus electrode and the cell body. Based on this, compared to related technologies, metal recombination on the surface of the solar cell can be reduced or eliminated, increasing the open-circuit voltage of the solar cell and thereby improving the cell efficiency of the solar cell. It should be understood that the solar cell can be a sliced ​​solar cell or a whole solar cell. Furthermore, the solar cell can also be a bifacial solar cell. Furthermore, the projections described in this application are all orthographic projections.

[0062] The above “at least a portion of the projection of the first conductive contact layer on the semiconductor substrate overlaps with the projection of the bus electrode on the semiconductor substrate” has the following situations. It should be understood that the following description is only for understanding and is not intended to be a specific limitation.

[0063] Example 1: A projection of a portion of the first conductive contact layer on the semiconductor substrate completely overlaps with a projection of a portion of the bus electrode on the semiconductor substrate.

[0064] For example, one possible form is: a solar cell includes five first conductive contact layers and three bus electrodes. The projections of two of the five first conductive contact layers on the semiconductor substrate completely overlap with the projections of two of the three bus electrodes on the semiconductor substrate. The number of first conductive contact layers is greater than the number of bus electrodes, and not all first conductive contact layers are located below the bus electrodes; some first conductive contact layers may be located between the bus electrodes.

[0065] Another possible form is: the solar cell includes five first conductive contact layers and five bus electrodes. The projections of two of the five first conductive contact layers on the semiconductor substrate completely overlap with the projections of two of the five bus electrodes on the semiconductor substrate. That is, not all first conductive contact layers are located beneath the bus electrodes; some first conductive contact layers may be located between the bus electrodes. Furthermore, not all bus electrodes have a first conductive contact layer beneath them; some bus electrodes may not have a first conductive contact layer beneath them.

[0066] Another possible form is: the solar cell includes five first conductive contact layers and three bus electrodes. The projections of three of the five first conductive contact layers on the semiconductor substrate completely overlap with the projections of three of the three bus electrodes on the semiconductor substrate. In other words, not all first conductive contact layers are located below the bus electrodes; some may be located between the bus electrodes.

[0067] Example 2: A projection of a portion of the first conductive contact layer on the semiconductor substrate partially overlaps with a projection of a portion of the bus electrode on the semiconductor substrate.

[0068] For example, a solar cell may include five first conductive contact layers and five bus electrodes. The projections of two of the five first conductive contact layers on the semiconductor substrate partially overlap with the projections of two of the five bus electrodes on the semiconductor substrate, i.e., the projections of the two overlap. This indicates that not all first conductive contact layers are located below the bus electrodes; some may be located between the bus electrodes.

[0069] Another possible form is that the solar cell includes five first conductive contact layers and three bus electrodes. The projections of two of the five first conductive contact layers on the semiconductor substrate partially overlap with the projections of two of the three bus electrodes on the semiconductor substrate, that is, the two overlap in an alternating manner. The number of first conductive contact layers is greater than the number of bus electrodes, and not all first conductive contact layers are located under the bus electrodes. Some first conductive contact layers are located between the bus electrodes. Furthermore, not all bus electrodes have a first conductive contact layer under them. Some bus electrodes do not have a first conductive contact layer under them.

[0070] Another possible form is: the solar cell includes five first conductive contact layers and three bus electrodes. The projections of three of the five first conductive contact layers on the semiconductor substrate partially overlap with the projections of three of the three bus electrodes on the semiconductor substrate, i.e., there is staggered overlap between the projections. The number of first conductive contact layers is greater than the number of bus electrodes, and not all first conductive contact layers are located below the bus electrodes; some may be located between the bus electrodes.

[0071] Example 3: A projection of a portion of the first conductive contact layer on the semiconductor substrate partially overlaps or completely overlaps with a projection of the bus electrode on the semiconductor substrate.

[0072] For example, a solar cell may include five first conductive contact layers and five bus electrodes. In this case, the projection of one of the five first conductive contact layers on the semiconductor substrate partially overlaps with the projection of one of the bus electrodes on the semiconductor substrate. The projection of another of the five first conductive contact layers on the semiconductor substrate completely overlaps with the projection of another of the bus electrodes on the semiconductor substrate. The remaining first conductive contact layers may be located between the bus electrodes.

[0073] Another possible form is: the solar cell includes five first conductive contact layers and three bus electrodes. In this case, the projection of one of the five first conductive contact layers on the semiconductor substrate partially overlaps with the projection of one of the bus electrodes on the semiconductor substrate. The projection of another of the five first conductive contact layers on the semiconductor substrate completely overlaps with the projection of another of the bus electrodes on the semiconductor substrate. The remaining first conductive contact layers may be located between the bus electrodes.

[0074] Example 4: The projections of all first conductive contact layers on the semiconductor substrate overlap with the projections of all bus electrodes on the semiconductor substrate.

[0075] For example, one possible form is: the solar cell includes five first conductive contact layers and five bus electrodes, wherein the projections of the five first conductive contact layers on the semiconductor substrate completely overlap with the projections of the five bus electrodes on the semiconductor substrate.

[0076] Another possible form is: the solar cell includes five first conductive contact layers and five bus electrodes, wherein the projections of the five first conductive contact layers on the semiconductor substrate partially overlap with the projections of the five bus electrodes on the semiconductor substrate, that is, the two overlap in a staggered manner.

[0077] In another possible form, the solar cell includes five first conductive contact layers and five bus electrodes, wherein the projections of the five first conductive contact layers on the semiconductor substrate partially overlap or completely overlap with the projections of the five bus electrodes on the semiconductor substrate.

[0078] As a possible implementation, the first direction and the second direction can be any two directions parallel to the surface of the semiconductor substrate and different from each other. Preferably, referring to Figures 1 to 3, the first direction A and the second direction B are orthogonal.

[0079] In actual application, the specific structure of the aforementioned solar cell can be determined according to the actual application scenario and is not specifically limited here. For example, the semiconductor substrate can be only a semiconductor substrate. Exemplarily, the semiconductor substrate can be a silicon substrate. In terms of conductivity type, the semiconductor substrate can be an intrinsic conductive substrate, an N-type conductive substrate or a P-type conductive substrate. Preferably, the semiconductor substrate is an N-type conductive substrate or a P-type conductive substrate. Compared with the intrinsic conductive substrate, the N-type conductive substrate or the P-type conductive substrate has a higher conductivity, which is beneficial to reducing the series resistance of the solar cell and improving the efficiency of the solar cell. From a structural point of view, when the first surface of the semiconductor substrate is the light-facing surface and the second surface is the backlight surface, the first surface of the semiconductor substrate can be a velvet surface to improve the light trapping effect of the light-facing surface of the solar cell, thereby improving the utilization rate of light by the solar cell; of course, the first surface of the semiconductor substrate can also be a plane; as for the second surface of the semiconductor substrate, it can be a polished surface or a velvet surface, which is not specifically limited here.

[0080] The first conductive contact layer 1 and the bus electrode 2, the collector electrode 3, and the second conductive contact layer 4 can be formed on the first surface and / or the second surface of the semiconductor substrate. When the first conductive contact layer 1 and the bus electrode 2, the collector electrode 3, and the second conductive contact layer 4 are formed on one surface of the semiconductor substrate, the structure of the other surface of the semiconductor substrate can be selected as needed. For example, when the first conductive contact layer 1 and the bus electrode 2, the collector electrode 3, and the second conductive contact layer 4 are formed on the light-facing surface of the semiconductor substrate, the backlight surface of the semiconductor substrate from the silicon substrate outward can be a tunneling oxide layer, a doped polysilicon layer, a passivation layer, and an electrode on the entire surface. In other cases, the backlight surface of the semiconductor substrate from the silicon substrate outward can be a passivation layer and an electrode.

[0081] The solar cell provided in this application is described below using three possible situations as examples. It should be understood that the following description is for understanding only and is not intended to be a specific limitation.

[0082] Example 1: From the second side to the first side of the semiconductor substrate, the solar cell may include an electrode (the electrode includes a bus electrode and a collector electrode), a semiconductor substrate, a conductive contact layer (the conductive contact layer includes a first conductive contact layer and a second conductive contact layer), and an electrode (the electrode includes a bus electrode and a collector electrode).

[0083] Example 2: From the second side to the first side of the semiconductor substrate, the solar cell may include an electrode (the electrode includes a bus electrode and a collector electrode), a conductive contact layer (the conductive contact layer includes a first conductive contact layer and a second conductive contact layer), a semiconductor substrate, and an electrode (the electrode includes a bus electrode and a collector electrode).

[0084] Example 3: From the second side to the first side of the semiconductor substrate, the solar cell may sequentially include an electrode (the electrode includes a bus electrode and a collector electrode), a conductive contact layer (the conductive contact layer includes a first conductive contact layer and a second conductive contact layer), a semiconductor substrate, a conductive contact layer (the conductive contact layer includes a first conductive contact layer and a second conductive contact layer), and an electrode (the electrode includes a bus electrode and a collector electrode).

[0085] It should be understood that, according to actual needs, the solar cell may further include other film layers in related technologies, such as aluminum oxide, silicon nitride, etc.

[0086] In an optional manner, the conductive contact layer disposed on at least one of the backlight surface and the light-facing surface of the semiconductor substrate is a local structure (see FIG1 ).

[0087] In an optional manner, the conductive contact layer located on the backlight side of the semiconductor substrate can be a full-surface structure or a partial structure (see FIG1 ). It should be understood that the full-surface structure means that the conductive contact layer completely covers the backlight side of the semiconductor substrate.

[0088] As a possible implementation, referring to Figures 1 to 3 , the solar cell further includes a second conductive contact layer 4. Multiple second conductive contact layers 4 extend along a second direction B and are spaced apart along a first direction A. The projection of the collector electrode 3 on at least one side of the semiconductor substrate overlaps with the projection of the second conductive contact layer 4 on the semiconductor substrate. Each first conductive contact layer intersects with multiple second conductive contact layers.

[0089] When the above technical solution is adopted, combined with the above description, since the solar cell includes a first conductive contact layer and a second conductive contact layer, this can not only reduce the contact resistivity and series resistance to effectively collect current and improve the cell efficiency of the solar cell, but also reduce the transmission distance of carriers to reduce the recombination loss of carriers during transmission. For example, the contact resistivity is reduced by 0.1mΩ*cm 2 to 2mΩ*cm2 , the series resistance dropped by 0.05mΩ to 0.5mΩ. See Figures 5 and 6 for a comparison of the series resistance of a solar cell in the related art and the series resistance of a solar cell provided by an embodiment of the present application. Referring to Figures 4 to 6, the embodiments of the present application mainly improve the front side of the solar cell, i.e., the light-facing side, while the contact resistance of the back area remains unchanged. Therefore, the back contact resistance, i.e., the resistance of the semiconductor substrate, the resistance of the bus electrode in contact with the conductive area, and the electrode contact resistance remain unchanged. Among them, Rs1 represents the contact resistance value of the collector electrode and the bus electrode in the front conductive area of ​​the semiconductor substrate, Rs2 represents the resistance value of the contact between the bottom of the first conductive contact layer and the bus electrode, Rs3 represents the resistance value of the PN junction region surface, that is, the uppermost layer of the semiconductor substrate toward the light surface and toward the bus electrode, Rs4 represents the resistance value of the leftmost and rightmost parts of the first conductive contact layer toward the bus electrode, Rs5 represents the resistance value of the first conductive contact layer and the second conductive contact layer toward the bus electrode, Rs6 represents the resistance value of the gold semiconductor contact formed by the first conductive contact layer and the bus electrode, Rs7 represents the resistance value of the back collector electrode, and Rs8 represents the resistance value of the back bus electrode.

[0090] Rs9 represents the contact resistance between the collector electrode and the bus electrode in the conductive area on the front side of the semiconductor substrate. Rs12 represents the resistance from the bottom of the first conductive contact layer to the bus electrode. Rs10 represents the resistance from the surface of the PN junction region, i.e., the top layer of the semiconductor substrate facing the light side, to the bus electrode. Rs11 represents the resistance from the leftmost and rightmost points of the first conductive contact layer to the bus electrode. Rs13 represents the resistance from the first and second conductive contact layers to the bus electrode. Rs14 represents the resistance of the metal-semiconductor contact formed between the first conductive contact layer and the bus electrode. Rs20 represents the resistance of the collector electrode. Rs21 represents the resistance of the bus electrode. Rs15, Rs16, Rs17, Rs18, and Rs19 represent the circuit connected in parallel with the first conductive contact layer, resulting from the addition of the second conductive contact layer. Rs15 represents the resistance from the surface of the N-junction region to the second conductive contact layer, Rs16 represents the resistance from the second conductive contact layer to the bus electrode, Rs17 represents the resistance from the bottom of the second conductive contact layer to the top of the second conductive contact layer, Rs18 represents the resistance from the semiconductor substrate to the second conductive contact layer, Rs19 represents the resistance between the second conductive contact layer and the metal contact, and Rs22 represents the resistance increase for each additional second conductive contact layer. The contact conductive region 6 located on the semiconductor substrate 5 has a conductivity type opposite to that of the first conductive contact layer 1. Furthermore, the arrows in Figure 4 indicate the direction of transport of photogenerated carriers.

[0091] Furthermore, referring to Figure 7, the current flow is shown when only the second conductive contact layer 4 is provided. Referring to Figure 8, the current flow is shown when both the first conductive contact layer 1 and the second conductive contact layer 4 are provided. As can be seen, providing both the first conductive contact layer 1 and the second conductive contact layer 4 can also reduce the current transmission distance, thereby reducing current loss.

[0092] Furthermore, the projection of the collector electrode on the semiconductor substrate overlaps with the projection of the second conductive contact layer on the semiconductor substrate. In this case, it can be understood that the projection of the collector electrode on the semiconductor substrate is located within the boundary of the projection of the second conductive contact layer on the semiconductor substrate. Preferably, when the projection of the collector electrode on the semiconductor substrate completely overlaps with the projection of the second conductive contact layer on the semiconductor substrate, and the two projected areas are completely equal, the second conductive contact layer can be prevented from blocking the semiconductor substrate, thereby preventing the semiconductor substrate from absorbing light and improving the cell efficiency of the solar cell.

[0093] As a possible implementation manner, the second conductive contact layer has a width of 30 μm to 200 μm, a length slightly smaller than that of the semiconductor substrate, and a thickness of 30 nm to 600 nm.

[0094] As a possible implementation, the first conductive contact layer and the second conductive contact layer can be composed of a P-type doped polysilicon layer and a tunneling layer, or can be composed of an N-type doped polysilicon layer and a tunneling layer. Exemplarily, the tunneling layer can be a silicon dioxide tunneling layer. The tunneling layer is formed on a semiconductor substrate, and a P-type doped polysilicon layer or an N-type doped polysilicon layer is formed on the tunneling layer. This structure not only has the effect of passivating dangling bonds on the silicon surface, but also can provide an electric field, which can allow majority carriers to form current through the electric field and prevent minority carriers from moving to the surface and being recombined. In addition, the metal-semiconductor contact of this structure has less metal recombination, so it can improve the passivation effect of the solar cell. Furthermore, the improvement in the passivation effect can significantly increase the open circuit voltage of the solar cell, thereby improving the battery efficiency.

[0095] For example, compared with the related art, the metal recombination (ie, the recombination current density in the metal contact area) is reduced from 1 fA to 20 fA, and the open circuit voltage is increased from 1 mV to 10 mV.

[0096] Regarding metal recombination losses, the contact between the metal and semiconductor is not a simple metal-semiconductor connection, but rather a metal-semiconductor alloy. During the alloying process, in addition to the alloy, some scattered metal powder will be free in the semiconductor. This metal in the semiconductor is a deep-level impurity and does not participate in conduction. At the same time, it will act as a recombination center, trapping electrons transmitted from the valence band to the conduction band, resulting in very serious metal recombination. Because the first and second conductive contact layers have high doping concentrations and can form alloys with a large amount of metal, the resulting free metal particles are relatively small. Furthermore, because the first and second conductive contact layers contain doped polysilicon layers and tunneling layers, the metal generally does not pass through the tunneling layer to contact the silicon substrate (i.e., the semiconductor base), thus reducing metal recombination.

[0097] As a possible implementation, referring to Figure 3 , the number of first conductive contact layers located between any two adjacent bus electrodes is greater than or equal to one. Since a first conductive contact layer is also present between any two adjacent bus electrodes, the carrier transmission distance can be further reduced, thereby further minimizing carrier recombination losses during transmission. Specifically, during transmission, carriers are recombined with impurity defects during transmission, thus shortening the transmission distance and reducing carrier recombination losses.

[0098] For example, current loss, shading loss and metal composite loss are collectively referred to as total loss. The total loss of solar cells in the related art is 300mA to 500mA, and the total loss of solar cells provided in the embodiments of the present application is 300mA to 450mA. The average composite current loss of a single solar cell is reduced by 5mA to 100mA.

[0099] For ease of description, the "first conductive contact layer overlapping the projection of the bus electrode on the semiconductor substrate" is defined as the third conductive contact layer, and the "first conductive contact layer located between any two adjacent bus electrodes" is defined as the fourth conductive contact layer. In other words, the first conductive contact layer includes the third and fourth conductive contact layers.

[0100] Exemplarily, the number of fourth conductive contact layers is greater than or equal to 1 and less than or equal to 5. For example, the number of fourth conductive contact layers can be 1, 2, 3, 4, or 5. When the number of fourth conductive contact layers is less than or equal to 5, the shielding of the semiconductor substrate by the fourth conductive contact layers can be reduced, thereby reducing the impact on the semiconductor substrate's absorption of light and improving the cell efficiency of the solar cell.

[0101] As a possible implementation, referring to FIG9 , it is assumed that when the first conductive contact layer is not provided (for ease of description, the horizontal axis in the figure is represented by "before optimization"), the cell efficiency of the solar cell has a baseline value of 0. When only the third conductive contact layer is provided (the horizontal axis in the figure is represented by "third"), the cell efficiency of the solar cell is improved compared to before optimization. When the number of the third conductive contact layer remains unchanged (i.e., the number of the third conductive contact layer remains unchanged to maintain a single variable), and the number of the fourth conductive contact layer is continuously increased (the horizontal axis in the figure is represented by "third + fourth + number of fourth conductive contact layers", where "number of fourth conductive contact layers" is represented by a number such as "1 or 2 or 3"), when the number of the fourth conductive contact layer increases to a certain value, the gain brought by the reduction of metal composite loss is less than the current loss caused by shading, and the cell efficiency of the solar cell no longer increases.

[0102] As a possible implementation, referring to FIG3 , the width of the first conductive contact layer (i.e., the fourth conductive contact layer 11) located between any two adjacent bus electrodes is greater than or equal to 10 microns and less than or equal to 150 microns, and the width direction of the first conductive contact layer is consistent with the second direction. For example, the width of the fourth conductive contact layer 11 can be 10 microns, 20 microns, 50 microns, 80 microns, 100 microns, or 150 microns.

[0103] This not only reduces the shielding of the semiconductor substrate by the fourth conductive contact layer 11, thereby reducing the impact on light absorption by the semiconductor substrate and improving the efficiency of the solar cell, but also enhances the passivation effect of the solar cell. Furthermore, it can also reduce the transmission distance of the current, thereby reducing current loss.

[0104] As a possible implementation, referring to FIG10 , when only the fourth conductive contact layer 11 is considered, only one first conductive contact layer (i.e., one fourth conductive contact layer 11) can be provided between every two adjacent bus electrodes. When multiple first conductive contact layers are provided between every two adjacent bus electrodes, it can be roughly considered as a splicing of multiple narrow lines. In this case, it can be found that as the width of the fourth conductive contact layer 11 increases, the current loss first decreases and then increases. Because the width of the fourth conductive contact layer 11 cannot be too wide, while the fourth conductive contact layer can provide certain passivation benefits and reduce recombination losses during carrier transmission due to the shortened transmission distance, the fourth conductive contact layer 11 also causes shading losses due to parasitic absorption. Only when the fourth conductive contact layer is within a certain range can the solar cell achieve optimal passivation, increase the solar cell's open-circuit voltage, shorten the transmission distance, increase the current, and minimize shading, resulting in minimal current loss. In other words, the solar cell's open-circuit voltage increases, and the gain from reducing recombination losses during transmission outweighs the current loss caused by shading, thereby improving cell efficiency.

[0105] As a possible implementation, referring to FIG2 , the width of the first conductive contact layer (i.e., the third conductive contact layer 10) overlapping with the projection of the bus electrode on the semiconductor substrate is greater than or equal to 50 microns and less than or equal to 300 microns, and the width direction of the first conductive contact layer is consistent with the second direction. For example, the width of the third conductive contact layer 10 can be 50 microns, 80 microns, 100 microns, 180 microns, 240 microns, or 300 microns.

[0106] At this time, the influence of the material for making the bus electrode on the size of the surface area of ​​the semiconductor substrate can be reduced, or the influence of the material for making the bus electrode on the surface of the semiconductor substrate can be avoided. Furthermore, in addition to the role of passivating the surface, the first conductive contact layer also needs to play the role of collecting the current collected by the collector electrode. Since the metal used in the solar cell in this application is generally a metal paste, the metal material used is mostly metal powder. The metal powder has a certain particle size, so it is easy to corrode downward when forming a metal semiconductor alloy. Based on this, the first conductive contact layer needs to have a certain thickness to prevent the metal from burning through the first conductive contact layer and directly contacting the semiconductor substrate. Therefore, the first conductive contact layer that overlaps with the projection of the bus electrode on the semiconductor substrate needs to have a certain thickness to play a blocking role to reduce metal recombination. In addition, the main function of the first conductive contact layer other than the first conductive contact layer directly below the bus electrode is to assist the second conductive contact layer in collecting current, reduce the transmission distance of the carrier, and thus reduce the recombination loss. However, since the parasitic absorption of the first conductive contact layer is strong (that is, when light passes through the first conductive contact layer, most of the light energy is absorbed by the first conductive contact layer, and no large number of photogenerated carriers are generated at the PN junction, the ineffective absorption is large, resulting in current loss), the thicker the first conductive contact layer, the lower the current. Furthermore, when the width of the first conductive contact layer is less than 50 μm, it is easily removed during the cleaning process. When the width of the first conductive contact layer is less than the width of the bus electrode, the first conductive contact layer cannot effectively collect current. When the first conductive contact layer is an incomplete structure, it not only cannot play an auxiliary transmission role, but will affect surface passivation. Furthermore, if the width of the first conductive contact layer is too wide, it will severely block light, causing the current to drop.

[0107] As a possible implementation, referring to Figure 11, when only the width of the third conductive contact layer is considered, the optimal efficiency is achieved when the width of the third conductive contact layer is close to the width of the bus electrode (current shading loss is not considered at this time). When the width of the third conductive contact layer is too narrow, the gain brought by the reduction of metal composite loss is too small, resulting in a low improvement in open circuit voltage and fill factor. When the width of the third conductive contact layer is too wide, the shading loss is large.

[0108] As a possible implementation, the length of the first conductive contact layer that overlaps with the projection of the bus electrode on the semiconductor substrate is less than the length of the semiconductor substrate and greater than the length of the bus electrode. The width of the first conductive contact layer that overlaps with the projection of the bus electrode on the semiconductor substrate is greater than the width of the bus electrode.

[0109] When the above technical solution is adopted, the bus electrode can be reduced or avoided from being in direct contact with the semiconductor substrate in terms of both length and width, so as to reduce or eliminate metal recombination on the surface of the solar cell, increase the open circuit voltage of the solar cell, and thus improve the cell efficiency of the solar cell.

[0110] As a possible implementation manner, the length of the first conductive contact layer located between any two adjacent bus electrodes is less than or equal to the length of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate; and / or the width of the first conductive contact layer located between any two adjacent bus electrodes is less than or equal to the width of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate; and / or the thickness of the first conductive contact layer located between any two adjacent bus electrodes is less than or equal to the thickness of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate.

[0111] When using the above technical solution, the entire current collection process for the entire solar cell is as follows: light shines on the solar cell surface, generating a large number of photogenerated carriers at the PN junction within the cell. Under the action of the built-in electric field, these photogenerated carriers are separated to the surface through the P and N regions or doped regions. The first conductive contact region at the surface, which forms a metal contact with the doped region, collects all unrecombined carriers that converge on the surface of the semiconductor substrate. Therefore, to better collect current, the first conductive contact region should cover the entire semiconductor substrate surface as much as possible, so the first conductive contact layer should be relatively long. However, light shines above the first conductive contact layer, and the parasitic absorption of the first conductive contact layer is relatively strong, that is, the ineffective absorption is relatively strong. Considering the above situation, the first conductive contact layer at the busbar electrode needs to be wider and thicker to prevent the metal from etching downward toward the edge of the semiconductor substrate. The length, width, and thickness of the first conductive contact layer between the busbar electrodes should be smaller than the length, width, and thickness of the first conductive contact layer in other areas.

[0112] Because the first conductive contact layer located between any two adjacent bus electrodes serves to transmit current, there is no need to prevent the bus electrodes from being in complete direct contact with the semiconductor substrate. Therefore, the first conductive contact layer located between any two adjacent bus electrodes can be smaller in length, width, and thickness than the first conductive contact layer that overlaps the projection of the bus electrodes on the semiconductor substrate, thereby saving manufacturing materials and reducing costs.

[0113] As a possible implementation, the thickness of the first conductive contact layer overlapping the projection of the bus electrode on the semiconductor substrate is greater than or equal to 30 nanometers and less than or equal to 600 nanometers, and the thickness direction of the first conductive contact layer is consistent with the direction from the first surface to the second surface of the semiconductor substrate. For example, the thickness of the first conductive contact layer can be 30 nanometers, 50 nanometers, 180 nanometers, 200 nanometers, 380 nanometers, 460 nanometers, or 600 nanometers.

[0114] Since the thickness of the first conductive contact layer is greater than or equal to 30 nanometers, the probability of the material used to make the busbar electrode burning through the semiconductor substrate can be reduced or eliminated, thereby reducing or eliminating metal recombination on the surface of the solar cell, thereby improving the cell efficiency of the solar cell. Furthermore, since the parasitic absorption of the first conductive contact layer is strong (i.e., when light passes through the first conductive contact layer, most of the light energy is absorbed by the first conductive layer, and no large amount of photogenerated carriers are generated at the PN junction, resulting in large ineffective absorption and current loss), a thicker first conductive contact layer will result in a decrease in current. Therefore, the thickness of the first conductive contact layer needs to be less than or equal to 600 nanometers.

[0115] In one embodiment, a ratio of an area of ​​the first conductive contact layer overlapping with a projection of the bus electrode on the semiconductor substrate to a sum of areas of the first conductive contact layer and the second conductive contact layer is greater than or equal to 0.1% and less than or equal to 5%. For example, the ratio may be 0.1%, 0.6%, 1%, 1.5%, 2.5%, 3.6%, 4%, or 5%.

[0116] Theoretically, the optimal solution is for the busbar electrode to completely cover the first conductive contact layer, overlapping its projection on the semiconductor substrate. However, in actual manufacturing, with the exception of a few costly and less mature metallization processes, such as electroplating and vapor deposition, conventional metallization solutions cannot achieve complete coverage. Therefore, under existing overprinting conditions, the optimal cell efficiency is achieved within the above range.

[0117] As a possible implementation, the ratio of the area of ​​the first conductive contact layer between two adjacent bus electrodes to the area of ​​the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate is greater than or equal to 5% and less than or equal to 20%. For example, the ratio can be 5%, 6%, 7%, 10%, 12%, 13%, 15%, or 20%.

[0118] When adopting the above technical solution, the passivation effect, parasitic absorption, current collection and gold-semiconductor contact are comprehensively considered. Within the above range, the passivation effect is optimal, the parasitic absorption is small, the current collection is more, the contact between the metal and semiconductor substrate is good, and the metal composite is small, thereby obtaining the best battery efficiency.

[0119] As a possible implementation, the ratio of the sum of the areas of the first and second conductive contact layers formed on the first surface of the semiconductor substrate to the area of ​​the first surface of the semiconductor substrate is greater than or equal to 5% and less than or equal to 15%. For example, the ratio can be 5%, 6%, 7%, 8%, 9%, 10%, or 15%. And / or the ratio of the sum of the areas of the first and second conductive contact layers formed on the second surface of the semiconductor substrate to the area of ​​the second surface of the semiconductor substrate is greater than or equal to 5% and less than or equal to 15%. For example, the ratio can be 5%, 6%, 7%, 8%, 9%, 10%, or 15%. In this case, the open-circuit voltage, short-circuit current, and fill factor of the solar cell can be taken into account to improve the cell efficiency of the solar cell.

[0120] When adopting the above technical solution, on the one hand, the conductive contact layer cannot block too much of the solar cell as a whole. Excessive blocking area will reduce the solar cell's absorption of light and the generation of photogenerated carriers. On the other hand, the photogenerated carriers generated by the entire solar cell need to be collected. Considering the efficiency of photogenerated carrier collection, the conductive contact layer should cover the entire surface as much as possible. However, considering the disadvantages of light blocking caused by the conductive contact layer, it cannot completely block the entire surface. Taking all these aspects into consideration, the first and second conductive contact layers are connected in a mesh shape, which not only avoids excessive blocking but also ensures current collection. In addition, the good passivation effect of the first and second conductive contact layers will enhance the passivation effect of the entire solar cell. However, too small an area will result in a longer current collection path, a larger series connection, and increased recombination losses. Higher doping concentrations in the first and second conductive contact layers are conducive to forming a good metal-semiconductor contact, while lower doping concentrations are conducive to reducing recombination. Therefore, it is necessary to comprehensively consider the area ratio and doping concentration to balance the open-circuit voltage, short-circuit current, and fill factor of the solar cell to form a cell structure with higher efficiency.

[0121] It should be understood that the area of ​​the first conductive contact layer is equal to the length of each first conductive contact layer multiplied by the width, multiplied by the number of first conductive contact layers. The area of ​​the second conductive contact layer is equal to the length of each second conductive contact layer multiplied by the width, multiplied by the number of second conductive contact layers.

[0122] As a possible implementation, the contact resistivity and series resistance of the solar cell decrease as the number of the first conductive contact layer increases. Specifically, assuming that when the first conductive contact layer is not provided, the contact resistivity and series resistance have a baseline value. When only the third conductive contact layer is provided, the contact resistivity and series resistance decrease. On the basis of the constant number of the third conductive contact layer (i.e., the number of the third conductive contact layer remains constant to maintain a single variable), when the number of the fourth conductive contact layer is continuously increased, the magnitude of the decrease in the contact resistivity continues to increase, and the magnitude of the decrease in the series resistance also continues to increase.

[0123] As a possible implementation, due to the reduced series resistance, the fill factor (FF) of the solar cell is significantly improved. For example, the fill factor is significantly improved by 0.1% to 0.8%.

[0124] As a possible implementation method, when the first conductive contact layer is not provided (for the sake of convenience of description, "before optimization" will be used as the representation), the current loss is large due to the obstruction of the bus electrode and the collector electrode. When only the third conductive contact layer is provided, the current loss is reduced compared to before optimization. On the basis of the unchanged number of the third conductive contact layer (that is, the number of the third conductive contact layer remains unchanged to maintain a single variable), when the number of the fourth conductive contact layer is continuously increased, the current loss continues to increase compared to both before optimization and when only the third conductive contact layer is provided. The number of the third conductive contact layer is equal to that of the bus electrode. Too many bus electrodes will block the semiconductor substrate. If the blocking area is too large, the current will drop. The number of the fourth conductive contact layer can be greater than the number of the third conductive contact layer. In this case, the number of the fourth conductive contact layer can be increased by reducing the width of the fourth conductive contact layer. Under the same blocking conditions, the carrier recombination during the transmission process is reduced by reducing the transmission distance.

[0125] As a possible implementation, assume that when the first conductive contact layer is not provided (for ease of description, "before optimization" will be used to represent it), the passivation effect of the solar cell is at a baseline level. When only the third conductive contact layer is provided, the passivation effect of the solar cell is improved compared to before optimization. Common knowledge indicates that the passivation effect of areas with the first conductive contact layer is better than that of areas without the first conductive contact layer. While the number of third conductive contact layers remains unchanged (i.e., the number of third conductive contact layers remains unchanged to maintain a single variable), the passivation effect of the solar cell continues to improve as the number of fourth conductive contact layers is continuously increased. It should be understood that the passivation effect is reflected in the photoluminescence brightness.

[0126] As a possible implementation, assume that the metal composite J0metal has a baseline value when the first conductive contact layer is absent (for ease of description, this will be referred to as "before optimization"). When only the third conductive contact layer is present, the metal composite J0metal decreases significantly compared to before optimization. While the number of third conductive contact layers remains constant (i.e., the number of third conductive contact layers remains constant to maintain a single variable), the decrease in metal composite J0metal remains minimal as the number of fourth conductive contact layers increases. As can be seen from the above, the metal composite J0metal decreases significantly only when only the third conductive contact layer is present, because the metal bus electrode experiences significant recombination losses when in contact with a semiconductor substrate without the first conductive contact layer. However, when the first conductive contact layer (i.e., the third conductive contact layer) is present directly below the bus electrode, the metal recombination losses are minimal.

[0127] In a second aspect, an embodiment of the present application further provides a method for manufacturing a solar cell. The method for manufacturing a solar cell comprises:

[0128] First, a semiconductor substrate is provided, wherein the semiconductor substrate has a first surface and a second surface opposite to each other;

[0129] Next, forming a first conductive contact layer extending along the first direction and spaced apart along the second direction on at least one surface of the semiconductor substrate;

[0130] Next, a plurality of bus electrodes extending along a first direction and spaced apart along a second direction are formed on the first conductive contact layer. The bus electrodes are located on at least one side of the semiconductor substrate. At least a portion of the projection of the first conductive contact layer on the semiconductor substrate overlaps with the projection of the bus electrodes on the semiconductor substrate, and the first direction is different from the second direction. A plurality of collector electrodes extending along the second direction and spaced apart along the first direction are formed, with each bus electrode intersecting with the plurality of collector electrodes.

[0131] In a solar cell manufactured using the solar cell manufacturing method provided in an embodiment of the present application, because at least a portion of the projection of the first conductive contact layer on the semiconductor substrate overlaps with the projection of the bus electrode on the semiconductor substrate, the bus electrode and the semiconductor substrate may be partially in direct contact or completely out of contact. This reduces or eliminates metal recombination on the solar cell surface, increases the open-circuit voltage of the solar cell, and thereby improves the cell efficiency of the solar cell, compared to related technologies.

[0132] In one possible implementation, the solar cell may be a bifacial solar cell.

[0133] As one possible implementation, multiple second conductive contact layers extending along a second direction and spaced apart along the first direction are formed on at least one surface of the semiconductor substrate. The projection of a collector electrode located on at least one surface of the semiconductor substrate overlaps with the projection of the second conductive contact layer on the semiconductor substrate, and each first conductive contact layer intersects with multiple second conductive contact layers.

[0134] As a possible implementation manner, the number of the first conductive contact layers located between any two adjacent bus electrodes is greater than or equal to one.

[0135] As a possible implementation manner, the length of the first conductive contact layer located between any two adjacent bus electrodes is less than or equal to the length of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate; and / or the width of the first conductive contact layer located between any two adjacent bus electrodes is less than or equal to the width of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate; and / or the thickness of the first conductive contact layer located between any two adjacent bus electrodes is less than or equal to the thickness of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate.

[0136] For a detailed description of the above content, please refer to the first aspect and will not be repeated here.

[0137] In the description of the above embodiments, specific features, structures, materials, or characteristics can be combined in any appropriate manner in any one or more embodiments or examples. The above description is only a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any person skilled in the art who can easily think of changes or replacements within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application shall be based on the scope of protection of the claims.

Claims

1. A solar cell comprising: A semiconductor substrate having a first surface and a second surface opposite to each other; A first conductive contact layer, formed on at least one side of the semiconductor substrate; A plurality of the first conductive contact layers extend along the first direction and are spaced apart along the second direction; A bus electrode, located at least on one side of the semiconductor substrate; the bus electrode is formed above the first conductive contact layer; The plurality of bus electrodes extend along a first direction and are spaced apart along a second direction; a projection of at least a portion of the first conductive contact layer on the semiconductor substrate overlaps with a projection of the bus electrode on the semiconductor substrate, and the first direction is different from the second direction; A plurality of collecting electrodes are extended along the second direction and spaced apart along the first direction; each of the bus electrodes intersects with the plurality of collecting electrodes.

2. The solar cell according to claim 1, further comprising: A second conductive contact layer, wherein a plurality of the second conductive contact layers extend along the second direction and are spaced apart and distributed along the first direction; A projection of the collector electrode located on at least one side of the semiconductor substrate on the semiconductor substrate overlaps with a projection of the second conductive contact layer on the semiconductor substrate; Each of the first conductive contact layers intersects with a plurality of the second conductive contact layers. 3 . The solar cell according to claim 1 , wherein the number of the first conductive contact layers between any two adjacent bus electrodes is greater than or equal to 1. 4 .

4. The solar cell according to claim 1 or 3, wherein a width of the first conductive contact layer between any two adjacent bus electrodes is greater than or equal to 10 microns and less than or equal to 150 microns; and a width direction of the first conductive contact layer is consistent with the second direction.

5. The solar cell according to claim 1, wherein a width of the first conductive contact layer overlapping with a projection of the bus electrode on the semiconductor substrate is greater than or equal to 50 micrometers and less than or equal to 300 micrometers; and a width direction of the first conductive contact layer is consistent with the second direction.

6. The solar cell according to claim 1, wherein a length of the first conductive contact layer overlapping with a projection of the bus electrode on the semiconductor substrate is smaller than a length of the semiconductor substrate and larger than a length of the bus electrode; A width of the first conductive contact layer overlapping a projection of the bus electrode on the semiconductor substrate is greater than a width of the bus electrode.

7. The solar cell according to claim 1, wherein the length of the first conductive contact layer between any two adjacent bus electrodes is less than or equal to the length of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate; and / or, the width of the first conductive contact layer between any two adjacent bus electrodes is less than or equal to the width of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate; And / or, the thickness of the first conductive contact layer between any two adjacent bus electrodes is less than or equal to the thickness of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate.

8. According to the solar cell of claim 1, the thickness of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate is greater than or equal to 30 nanometers and less than or equal to 600 nanometers; the thickness direction of the first conductive contact layer is consistent with the direction from the first surface to the second surface of the semiconductor substrate.

9. The solar cell according to claim 2, wherein the ratio of the area of ​​the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate to the sum of the areas of the first conductive contact layer and the second conductive contact layer is greater than or equal to 0.1% and less than or equal to 5%.

10. The solar cell according to claim 1, wherein a ratio of an area of ​​the first conductive contact layer between two adjacent bus electrodes to an area of ​​the first conductive contact layer overlapping with a projection of the bus electrode on the semiconductor substrate is greater than or equal to 5% and less than or equal to 20%.

11. The solar cell according to claim 1, wherein a ratio of a sum of an area of ​​the first conductive contact layer and a second conductive contact layer formed on the first surface of the semiconductor substrate to an area of ​​the first surface of the semiconductor substrate is greater than or equal to 5% and less than or equal to 15%; And / or, a ratio of a sum of an area of ​​the first conductive contact layer and a second conductive contact layer formed on the second surface of the semiconductor substrate to an area of ​​the second surface of the semiconductor substrate is greater than or equal to 5% and less than or equal to 15%.

12. A method for manufacturing a solar cell, comprising: Providing a semiconductor substrate; The semiconductor substrate has a first surface and a second surface opposite to each other; Forming a first conductive contact layer extending along a first direction and spaced apart along a second direction at least on one surface of the semiconductor substrate; A plurality of bus electrodes extending along a first direction and spaced apart along a second direction are formed on the first conductive contact layer; the bus electrodes are located on at least one side of the semiconductor substrate; a projection of at least part of the first conductive contact layer on the semiconductor substrate overlaps with a projection of the bus electrodes on the semiconductor substrate, and the first direction is different from the second direction; A plurality of collector electrodes extending along the second direction and spaced apart along the first direction are formed; each of the bus electrodes intersects with a plurality of the collector electrodes.

13. The method for manufacturing a solar cell according to claim 12, Forming a plurality of second conductive contact layers extending along the second direction and spaced apart along the first direction on at least one surface of the semiconductor substrate; The projection of the collector electrode located on at least one side of the semiconductor substrate on the semiconductor substrate overlaps with the projection of the second conductive contact layer on the semiconductor substrate; each of the first conductive contact layers intersects with a plurality of the second conductive contact layers. 14 . The method for manufacturing a solar cell according to claim 12 , wherein the number of the first conductive contact layers located between any two adjacent bus electrodes is greater than or equal to 1.

15. The method for manufacturing a solar cell according to claim 12, wherein the length of the first conductive contact layer between any two adjacent bus electrodes is less than or equal to the length of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate; and / or, the width of the first conductive contact layer between any two adjacent bus electrodes is less than or equal to the width of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate; And / or, the thickness of the first conductive contact layer between any two adjacent bus electrodes is less than or equal to the thickness of the first conductive contact layer overlapping with the projection of the bus electrode on the semiconductor substrate.

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