Back-contact solar cell and method for manufacturing the same, and photovoltaic assembly

Abstract

The present invention provides a back-contact solar cell, a method for manufacturing the same, and a photovoltaic assembly. [Solution] The back-contact solar cell comprises a crystalline silicon substrate and a first functional film. A first region and a separation region are arranged on the back surface of the crystalline silicon substrate, with the separation region located on one side of the first region. The first functional film is laminated and arranged on the first region, and the first functional film has a light trap portion immediately adjacent to the separation region. The light trap portion has at least one of a light trap valley and a light trap peak, however, the light trap valley is reduced in diameter in the direction from the tank opening to the tank bottom, and the side walls of the light trap peak are expanded outward in the direction from the top to the bottom. Here, both the reduced-diameter light trap valley and the outwardly expanded light trap peak reflect incident light into the interior of the first functional film and the crystalline silicon substrate, performing a light trapping effect and improving the utilization rate of back-incident light.

Description

[Technical Field]

[0001] The present invention relates to the technical field of photovoltaic energy, and more particularly to back-contact solar cells, methods for manufacturing the same, and photovoltaic assemblies. [Background technology]

[0002] Under the actual operating conditions of back-contact solar cells, light not only enters the back of the back-contact solar cell after being reflected, but also after being reflected. While back-contact solar cells can effectively utilize the light incident from the front, their utilization efficiency of light incident from the back is low, which limits the bifacial power generation coefficient of back-contact solar cells. [Overview of the project]

[0003] In light of the above, it is necessary to provide a back-contact solar cell capable of improving the utilization rate of backlighting to address the aforementioned problems mentioned in the background technology. The present invention is a back-contact type solar cell, A crystalline silicon substrate having a first region, a second region and a separation region arranged on its back surface, wherein the separation region is positioned between the first region and the second region, and the first region and the second region are separated from each other via the separation region. A first functional film comprising a first tunnel layer and a first dope layer sequentially stacked and arranged in the first region, wherein the first functional film has a light trap portion immediately adjacent to the isolation region, and at least one of a light trap valley and a light trap peak is arranged in the light trap portion, wherein, along the thickness direction adjacent to the crystalline silicon substrate, the diameter of the light trap valley is reduced in the direction from the tank opening to the tank bottom, and the diameter of the side walls of the light trap peak is increased outward in the direction from the top to the bottom edge of the first functional film, The present invention provides a back-contact solar cell comprising a second functional film including a second tunnel layer and a second dope layer sequentially stacked and arranged in the second region, wherein the dope type of the second dope layer and the first dope layer are reversed. In some embodiments of the present invention, the light trap section includes a plurality of light trap peaks arranged in a continuous manner, and two adjacent light trap peaks are connected at the bottom ends of their side walls. In some embodiments of the present invention, the first functional membrane has a first boundary immediately adjacent to the separation region, and the second functional membrane has a second boundary immediately adjacent to the separation region, wherein the variation in the distance of the first boundary from the median of the separation region is greater than the variation in the distance of the second boundary from the median of the separation region. In some embodiments of the present invention, the value of the variance of the first boundary is 30 to 100. In some embodiments of the present invention, the height difference between the edge of the light trap portion closest to the crystalline silicon substrate and the ceiling surface of the first functional film is 0.5 μm to 6 μm. In some embodiments of the present invention, the height difference between the edge of the light trap portion closest to the crystalline silicon substrate and the ceiling surface of the first functional film is 3 μm to 6 μm. In some embodiments of the present invention, the surface of the isolation region of the crystalline silicon substrate has a flocked surface structure, and the height difference between the bottom edge of the light trap portion and the ceiling surface of the first functional film is greater than the height difference between the bottom edge of the adjacent isolation region and the ceiling surface of the first functional film. In some embodiments of the present invention, the doping type of the first doping layer is N-type, and the doping type of the second doping layer is P-type. In some embodiments of the present invention, the first functional film further comprises at least one of a first passivation layer and a first anti-reflective layer laminated and / or arranged on the first dope layer, The second functional film further comprises at least one of a second passivation layer and a second anti-reflective layer, which are laminated and arranged on the second dope layer. Furthermore, the present invention relates to a method for manufacturing a back-contact solar cell as described in any one of the above embodiments, The process involves sequentially forming the second tunnel layer and the second dope layer in the second region of the crystalline silicon substrate, and sequentially forming the first tunnel layer, the first dope layer, and the first doped oxide layer in the first region of the crystalline silicon substrate. The first doped oxide layer has a light trapping treatment area immediately adjacent to the separation area, and the process involves removing a portion of the first doped oxide layer in the light trapping treatment area to expose the first doped layer located below, The present invention provides a method for manufacturing a back-contact solar cell, which includes the step of corroding the first doped oxide layer, the first doped layer, and the first tunnel layer with an alkaline solution to form the light trap portion. In some embodiments of the present invention, the step of removing a portion of the first doped oxide layer in the light trapping region includes scanning the light trapping region with a target laser, During the scanning process, the optical spot of the target laser has a high-energy region and a low-energy region, and the power density of the high-energy region is >0.25 J / cm². 2 Therefore, the power density in the low-energy region is ≤0.25 J / cm². 2 is, or, During the scanning process, the target laser is controlled to scan only the local area of ​​the light trapping region. In some embodiments of the present invention, in the step of depositing the first tunnel layer and the first dope layer on the crystalline silicon substrate, the first tunnel layer, the first dope layer and the first dope oxide layer are deposited in the separation region with an extension, The manufacturing method further includes a step of dissolving and removing the first doped oxide layer located in the separation region using a separation region laser. In some embodiments of the present invention, in the step of corroding the first tunnel layer and the first dope layer with an alkaline solution, a flocculating agent is used as the alkaline solution, and the flocculating agent is used to simultaneously perform a flocculating treatment on the front and back surfaces of the crystalline silicon substrate. Furthermore, the present invention provides a photovoltaic assembly comprising a back-contact solar cell described in the above-described embodiment, or a back-contact solar cell manufactured by the method for manufacturing a back-contact solar cell described in the above-described embodiment. The back-contact solar cell according to the present invention includes a crystalline silicon substrate, a first functional film and a second functional film laminated on the crystalline silicon substrate, the first and second functional films each used to derive two different types of carriers, and the first functional film has a light trap portion immediately adjacent to the isolation region. The light trap portion has light trap valleys and light trap peaks. Here, both the reduced-diameter light trap valleys and the outwardly expanded light trap peaks reduce the reflectivity of light incident from the back of the back-contact solar cell into the first functional film and the crystalline silicon substrate, and further improve the utilization rate of light incident from the back of the back-contact solar cell by the crystalline silicon substrate, thereby performing a light trapping effect and improving the utilization rate of back-incident light. This effectively increases the bifacial factor of the back-contact solar cell and further improves the efficiency of the back-contact solar cell. The above description is merely an overview of the technical means of the present invention. In order to better understand the technical means of the present invention and to enable implementation according to the contents of this specification, preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. [Brief explanation of the drawing]

[0004] To more clearly explain the technical means according to the embodiments of the present invention, the drawings necessary for the description of the embodiments will be briefly described below. Needless to say, the drawings described below only relate to some embodiments of the present invention. For those skilled in the art, based on these drawings, drawings related to other embodiments can also be obtained on the premise of not performing creative labor. [Figure 1] It is a schematic cross-sectional structure diagram of a type of back-contact solar cell according to the present invention; [Figure 2] FIG. 2A is a schematic partial cross-sectional structure diagram of the light trap portion in the first functional film in FIG. 1, and FIG. 2B is an optical path diagram of the incident light shown in FIG. 2A; [Figure 3] It is a schematic plan view structure diagram of a partial cross-section of the first functional film, the separation region, and the second functional film in FIG. 1; [Figure 4] It is a schematic process diagram of a manufacturing method of a back-contact solar cell; [Figure 5] It is a schematic cross-sectional structure diagram in which a second tunnel layer and a second doped layer are deposited on a crystalline silicon substrate; [Figure 6] It is a schematic structure diagram in which the second tunnel layer and the second doped layer outside the second region are removed from the structure shown in FIG. 5; [Figure 7] It is a schematic structure diagram in which a first tunnel layer and a first doped layer are laminated based on the structure shown in FIG. 6; [Figure 8] It is a schematic diagram showing the control of the energy density distribution of the light spot of the target laser; [Figure 9] It is a schematic structure diagram showing the control of the scanning region of the target laser; [Figure 10] It is a schematic cross-sectional structure diagram of the structure shown in FIG. 7 corroded by an alkaline solution; [Figure 11] It is a partially enlarged plan view containing the light trap portion according to Example 1; [Figure 12] It is a plan view of the separation region; [Figure 13]This is a schematic cross-sectional diagram of a separation region having a light trap section. Here, each drawing symbol and its meaning are as follows: 100, crystalline silicon substrate; 1001, first boundary; 1002, second boundary; 101, first region; 102, second region; 103, separation region; 110, first functional film; 1100, light trap section; 1101, light trap peak; 1102, light trap valley; 1103, side wall; 111, first tunnel layer; 112, first doping layer; 113, first passivation layer; 114, first anti-reflective layer; 120, second functional Film; 121, second tunnel layer; 122, second dope layer; 123, second passivation layer; 124, second anti-reflective layer; 130, front passivation layer; 140, front anti-reflective layer; 150, first electrode; 160, second electrode; 210, first doped oxide layer; 220, second doped oxide layer; 301, light trap processing area; 310, target laser; 311, high energy region; 312, low energy region. [Modes for carrying out the invention]

[0005] To facilitate understanding of the present invention, the invention will be described more comprehensively below. This specification describes optimal embodiments of the invention. However, the invention can be implemented in various different forms and is not limited to the embodiments described herein. Conversely, the purpose of providing these embodiments is to make the content of the invention more transparent and comprehensive.

[0006] Unless otherwise defined, all technical and scientific terms used in this invention shall have the same meaning as those commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification are for illustrative purposes only and are not intended to limit the invention.

[0007] It should be understood that when an element or layer is referred to as "on top of," "adjacent to," "connected to," or "coupled to" another element or layer, it may be directly on top of, adjacent to, connected to, or coupled to the other element or layer, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on top of," "directly adjacent to," "directly connected to," or "directly coupled to" another element or layer, it is assumed that there are no intervening elements or layers. It should be understood that various elements, components, regions, layers, and / or parts can be described using terms such as 1st, 2nd, 3rd, etc., but these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are merely used to distinguish one element, component, region, layer, or part from another element, component, region, layer, or part.

[0008] In this specification, for the sake of clarity, spatial terms such as "below," "below," "downward," "below," "above," and "upper" are used to describe the relationship of one element or feature to another. It should be understood that spatial terms are intended to include different orientations of a device in use or operation. For example, if a device in a drawing is turned upside down, an element or feature originally described as being "below" or "below" another element or "below" it will be oriented as being "above" the other element or feature. Thus, the exemplary terms "below" and "below" include two orientations: up and down. It is also permitted that a device may be oriented differently (e.g., rotated 90 degrees or oriented in other ways), and the spatial descriptions used in such cases should be interpreted accordingly.

[0009] The terms used herein are for the purpose of describing specific embodiments and do not limit the invention. Where used herein, the singular forms “1,” “one,” and “the” are intended to include the plural form unless otherwise explicitly indicated in the context. Furthermore, it should be understood that, where used herein, the terms “composition” and / or “contain” determine the presence of features, integers, processes, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, processes, operations, elements, components, and / or combinations thereof. Where used herein, the terms “and / or” include any and all combinations of the relevant enumerated items.

[0010] The present invention provides a back-contact solar cell comprising a crystalline silicon substrate, a first functional film, and a second functional film. A first region, a second region, and a separation region are arranged on the back surface of the crystalline silicon substrate, with the separation region positioned between the first and second regions, and the first and second regions separated from each other via the separation region. The first functional film has a first tunnel layer and a first dope layer sequentially stacked on the first region. The first functional film has a light trap portion immediately adjacent to the separation region, and the light trap portion has at least one of a light trap valley and a light trap peak. Here, a light trap peak refers to a convex undulation structure located on the crystalline silicon substrate that has a pointed or nearly pointed shape, and a light trap valley may have a narrow, long channel shape immediately adjacent to the light trap peak, or it may have a groove shape separated from the light trap peak. The light trap valley is reduced in diameter in the direction from the tank opening to the tank bottom, and the side walls of the light trap peak are increased in diameter outward in the direction from the top to the bottom. Here, the top of the sidewall refers to the end of the sidewall furthest from the crystalline silicon substrate, and the bottom of the sidewall refers to the end of the sidewall closest to the crystalline silicon substrate. The second functional film includes a second tunnel layer and a second doping layer that are sequentially stacked and arranged in the second region, with the doping types being reversed between the second doping layer and the first doping layer.

[0011] The back-contact solar cell according to the present invention includes a crystalline silicon substrate, a first functional film and a second functional film laminated on the crystalline silicon substrate, the first and second functional films each used to guide two different types of carriers, and the first functional film has a light trap portion immediately adjacent to the isolation region. The light trap portion has light trap valleys and light trap peaks. Here, the light trap valleys, which are reduced in diameter along the thickness direction close to the crystalline silicon substrate, and the light trap peaks, which are expanded outward, both reduce the reflectance of light incident from the back of the back-contact solar cell into the first functional film and the crystalline silicon substrate, and further improve the utilization rate of light incident from the back of the back-contact solar cell that is absorbed by the crystalline silicon substrate, thereby performing a light trapping effect and improving the utilization rate of light incident from the back by the crystalline silicon substrate. As a result, the bifacial power generation coefficient of the back-contact solar cell can be effectively increased, and the efficiency of the back-contact solar cell can be further improved.

[0012] Figure 1 is a schematic cross-sectional diagram of a back-contact solar cell according to the present invention. As shown in Figure 1, the back-contact solar cell comprises a crystalline silicon substrate 100, a first functional film 110, and a second functional film 120. A first region 101, a second region 102, and an isolation region 103 are arranged on the back surface of the crystalline silicon substrate 100, with the isolation region 103 positioned between the first region 101 and the second region 102. The first functional film 110 is stacked on the first region 101, and the second functional film 120 is stacked on the second region 102.

[0013] To make it easier to understand, of the photogenerated carriers produced on the crystalline silicon substrate 100, one type of conductive carrier is derived from the first region 101, and the other type of conductive carrier is derived from the second region 102.

[0014] To make it easier to understand, as shown in Figure 1, the first functional film 110 and the second functional film 120 are separated from each other by a separation region 103. The doping type of the first functional film 110 is different from that of the second functional film 120. The first functional film 110 and the second functional film 120 are used to derive carriers of different conductivity types from the crystalline silicon substrate 100, respectively. The first functional film 110 and the second functional film 120 are also used to passivate the surface of the crystalline silicon substrate 100, thereby reducing the interfacial recombination loss of carriers between the crystalline silicon substrate and the doped layer.

[0015] As shown in Figure 1, in some examples of this embodiment, the crystalline silicon substrate 100 may have a plurality of first regions 101 and second regions 102, and each first region 101 and its adjacent second region 102 are separated from each other by a separation region 103. A first functional film 110 is placed in each first region 101, and a second functional film 120 is placed in each second region 102.

[0016] Figure 2A is a schematic diagram of a partial cross-sectional structure of a light trap portion 1100 in the first functional film 110. As shown in Figure 2A, the light trap portion 1100 is positioned immediately adjacent to the separation region 103, and at least one of a light trap valley 1102 and a light trap peak 1101 is provided in the light trap portion 1100. Here, along the thickness direction adjacent to the crystalline silicon substrate 100, the light trap valley 1102 is reduced in diameter from the tank opening to the tank bottom, and the side walls of the light trap peak 1101 are increased in diameter outward from the top to the bottom.

[0017] As shown in Figure 2A, in some examples of this embodiment, the light trap section 1100 may have both a light trap valley 1102 and a light trap peak 1101 arranged simultaneously so as to further enhance the light trapping ability of the first functional film 110.

[0018] As shown in Figure 2A, in some examples of this embodiment, the light trap section 1100 may include a plurality of continuously arranged light trap peaks 1101. The bottom ends of the side walls of two adjacent light trap peaks 1101 are connected to each other. The plurality of continuously arranged light trap peaks 1101 form a sawtooth structure in the direction along the surface of the crystalline silicon substrate 100. Compared to a single light trap peak 1101, the reciprocal reflection by two adjacent side walls in the plurality of light trap peaks 1101 further improves the absorption rate of the light trap section 1100 for light incident from the back of the back of the back-contact solar cell.

[0019] In this example, the top of a single light trap mountain 1101 is pointed, meaning the top of the light trap mountain 1101 is either point-shaped or linear. If the top of a single light trap mountain 1101 is linear, the light trap mountain 1101 as a whole can be ridge-shaped, while if the top of a single light trap mountain 1101 is point-shaped, the light trap mountain 1101 as a whole can be ridge-shaped.

[0020] As shown in Figure 2A, in this embodiment, the height difference between the edge of the light trap section 1100 closest to the crystalline silicon substrate 100 and the ceiling surface of the first functional film 110 is 0.5 μm to 6 μm. For example, the height difference between the edge of the light trap section 1100 closest to the crystalline silicon substrate 100 and the ceiling surface of the first functional film 110 may be 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 5 μm, or 6 μm, or the height difference between the edge of the light trap section 1100 closest to the crystalline silicon substrate 100 and the ceiling surface of the first functional film 110 may be a value between any two of the above height differences.

[0021] To make it easier to understand, the top of the light trap section 1100 is the end furthest from the crystalline silicon substrate 100 in the overall structure of the light trap section 1100, and the bottom of the light trap section 1100 is the end closest to the crystalline silicon substrate 100 in the overall structure of the light trap section 1100.

[0022] Furthermore, the height difference between the edge of the light trap section 1100 closest to the crystalline silicon substrate 100 and the top surface of the first functional film 110 is 3 μm to 6 μm. For example, the height difference between the edge of the light trap section 1100 closest to the crystalline silicon substrate 100 and the top surface of the first functional film 110 may be 3 μm, 3.5 μm, 4 μm, 5 μm, or 6 μm, or it may be a value between any two of the above height differences. This height difference is clearly higher than the height of a typical pyramidal flocked surface structure. By setting it in this way, the capture area for light incident from the back of the battery by the light trap section 1100 can be further increased, and the utilization rate of incident light by the crystalline silicon substrate 100 can be improved.

[0023] As shown in Figure 2A, in this embodiment, the surface of the isolation region 103 of the crystalline silicon substrate 100 has a flocked surface structure. As can be seen, the flocked surface structure is not flat but has an uneven appearance, and the overall structure of the flocked surface structure has a top that is furthest from the crystalline silicon substrate 100 and a bottom that is closest to the crystalline silicon substrate 100. The height difference between the bottom of the light trap portion 1100 and the top surface of the first functional film 110 is greater than the height difference between the bottom of the adjacent isolation region 103 and the top surface of the first functional film 110.

[0024] As some examples of this embodiment, the distance between the top and bottom of each light trap mound 1101 is 0.5 μm to 6 μm. With light trap mounds 1101 of this height, it is possible to provide good light trapping performance while maximizing the area ratio of the first functional film 110 on the back of the battery, and ensuring that the first functional film 110 still has good passivation performance and carrier collection capability.

[0025] In this example, the height difference between the top and bottom of the light trap mound 1101 may be 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 5 μm, or 6 μm, or it may be a value between any two of the above height differences. To make it clear, the heights of multiple light trap mounds 1101 may be the same or different.

[0026] Figure 2A shows a cross-section of the light trap valley 1102. As can be seen, the light trap valley 1102 may have a conical or pyramidal shape overall, that is, the bottom of the light trap valley 1102 may be pointed.

[0027] As some examples of this embodiment, the light trap section 1100 includes a light trap valley 1102 and a light trap peak 1101, and the light trap valley 1102 is located on one side of the light trap peak 1101 that is far from the separation region 103.

[0028] As some examples of this embodiment, the light trap section 1100 may have multiple light trap valleys 1102, and two adjacent light trap valleys 1102 may be located immediately next to each other or separated from each other.

[0029] As some examples of this embodiment, the depth of the light trap valley 1102 may be 0.5 μm to 6 μm. Furthermore, the depth of the light trap valley 1102 may be 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 5 μm, or 6 μm, or the depth of the light trap valley 1102 may be a value between any two of the above depths.

[0030] To facilitate understanding, Figure 2A shows a partial cross-sectional structure in the direction of extension from the separation region 103 toward the first region 101 (i.e., the x-direction in Figure 1), showing a single light trap portion 1100. In some examples of this embodiment, the first functional film 110 includes multiple light trap portions 1100, each of which is immediately adjacent to the separation region 103 and separated from one another.

[0031] Figure 2B is an optical path diagram of the incident light shown in Figure 2A. The solid line with an arrow in Figure 2B indicates the incident light. As shown in Figure 2B, when incident light is irradiated onto the side wall 1103 of the light trap peak 1101, a portion of the incident light passes through the light trap peak 1101 and enters the crystalline silicon substrate 100, where it is absorbed. Another portion is reflected by the side wall of the light trap peak 1101 toward the crystalline silicon substrate 100 and further absorbed by the crystalline silicon substrate 100. Furthermore, compared to a typical pyramidal flocked surface structure, the height dimension of the light trap peak 1101 in this embodiment is significantly larger, and the depth dimension of the light trap valley 1102 is also significantly larger. This is advantageous in that a large amount of incident light is refracted or reflected by the light trap peak 1101 and the light trap valley 1102. Therefore, the light trap section 1100 having the light trap peak 1101 and the light trap valley 1102 can significantly improve the absorption rate of incident light.

[0032] Figure 3 is a schematic plan view of a partial cross-sectional structure of the first functional film 110, the isolation region 103, and the second functional film 120 in Figure 1. In this embodiment, the direction of extension of the boundary line between the first region 101 and the isolation region 103 (i.e., the y-direction in Figure 3) is perpendicular to the plane in which the cross-section in Figure 1 is located. As shown in Figure 3, the multiple light trap units 1100 may be arranged sequentially along the boundary line between the first region 101 and the isolation region 103. The multiple light trap units 1100 can further improve the light absorption rate by the back surface of the crystalline silicon substrate 100. In addition, the multiple light trap units 1100 arranged apart from each other can increase the area ratio of the light trap units 1100 on the back surface of the battery while reducing damage to the first functional film 110, thereby ensuring that the first functional film 110 still has good carrier collection capability. Furthermore, if the entire edge immediately adjacent to the separation region 103 in the first functional film 110 is made into a light trap section 1100, a good light absorption rate can be obtained and more carriers can be generated, but the proportion of the first functional film 110 decreases, further reducing the carrier collection capacity.

[0033] To make it clear, the light trap section 1100 has one end that is furthest from the separation region 103, and the end of the light trap section 1100 that is furthest from the separation region 103 can be determined by the light trap valley 1102 and / or light trap peak 1101 that are furthest from the separation region 103. As shown in Figure 3, the distance between the end of the light trap section 1100 that is furthest from the separation region 103 and the separation region 103 is d1. As some examples of this embodiment, the distance d1 between the end of the light trap section 1100 that is furthest from the separation region 103 and the separation region 103 is ≤25 μm. For example, the distance d1 between the furthest end of the light trap section 1100 from the isolation region 103 and the isolation region 103 can be 5 μm, 10 μm, 15 μm, 20 μm, or 25 μm, or the distance d1 between the furthest end of the light trap section 1100 from the isolation region 103 and the isolation region 103 can be a value between any two of the above distances. Designing the light trap section 1100 with such a specific distance range is advantageous in considering good light absorption performance and maintaining good carrier collection capability of the first functional film 110, thereby significantly improving the efficiency of the back-contact solar cell.

[0034] As shown in Figure 3, the distance between two adjacent light trap sections 1100 is d2, meaning that there is a distance of length d2 between the end of the previous light trap section 1100 and the front of the next light trap section 1100. In some examples of this embodiment, the distance d2 between two adjacent light trap sections 1100 is 20 μm to 200 μm. The first functional film 110 located between two adjacent light trap sections 1100 can maintain a complete passivation contact structure. Designing light trap sections with such specific spacings is advantageous in considering good light absorption performance and ensuring the carrier collection capability of the first functional film 110, thereby significantly improving the efficiency of the back-contact solar cell.

[0035] In this example, the distance between two adjacent light trap units 1100 may be 20 μm, 30 μm, 50 μm, 70 μm, 100 μm, 120 μm, 150 μm, 170 μm, or 200 μm, or the distance between two adjacent light trap units 1100 may be a value between any two of the above distances.

[0036] As shown in Figure 3, a single light trap section 1100 has a length d3 along the extending direction of the boundary between the first region 101 and the separation region 103. In some examples of this embodiment, the length d3 of the single light trap section 1100 is 10 μm to 90 μm. In this example, the length of the single light trap section 1100 may be 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, or 90 μm, or the length of the single light trap section 1100 may be a value between any two of the above lengths.

[0037] As shown in Figures 3 and 12, the first functional membrane 110 has a first boundary 1001 immediately adjacent to the separation region 103, and the second functional membrane 120 has a second boundary 1002 immediately adjacent to the separation region 103, with the overall variability variance of the first boundary 1001 being greater than the overall variability variance of the second boundary 1002. Here, the "variability variance" of the first boundary 1001 and the second boundary 1002 should be understood as the degree of deviation of the first boundary 1001 with respect to the direction of extension of the separation region 103. As can be understood, since the first functional membrane 110 has a light trap section 1100 at the first boundary 1001 adjacent to the separation region 103, the overall variability variance of the first boundary 1001 is greater than the overall variability variance of the second boundary 1002.

[0038] As an example, the variability variance of the first boundary 1001 is 30 to 100. Designing the first boundary to have a specific variability variance range as described above is advantageous in considering good light absorption performance and ensuring the carrier collection capability of the first functional film 110, thereby significantly improving the efficiency of the back-contact solar cell. As an example, the "variability variance" of the first boundary 1001 can be determined by the following method. First, a separation region 103 having a length of 100 μm to 500 μm is selected, and a plurality of points uniformly distributed across the entire first boundary 1001 are selected, some of which should be located in the light trap section 1100. At the same time, a line located in the central region of the separation region 103 and approximately parallel to the extension direction of the separation region 103 is selected as a reference line, the distances of the plurality of points on the first boundary 1001 from the reference line are obtained, and the variance is calculated for these obtained distances. The larger the variance, the greater the deviation in the distribution of these distances, meaning that the variance of the first boundary 1001 is larger. The variance of the second boundary 1002 can be obtained in a similar manner.

[0039] As some examples of this embodiment, the first functional film 110 includes a first tunnel layer 111 and a first doping layer 112, which are sequentially stacked and arranged on a first region 101 of a crystalline silicon substrate 100. Here, the first tunnel layer 111 is for separating the first doping layer 112 from the crystalline silicon substrate 100, and the first tunnel layer 111 allows carriers to pass through the crystalline silicon substrate 100 while passivating it. The first doping layer 112 is for selectively collecting carriers.

[0040] As some examples of this embodiment, the material of the first tunnel layer 111 may be one or more selected from amorphous silicon, intrinsic amorphous silicon, hydrogenated amorphous silicon, intrinsic hydrogenated amorphous silicon, or silicon oxide.

[0041] As some examples of this embodiment, the thickness of the first tunnel layer 111 may be 1 nm to 3 nm.

[0042] As some examples of this embodiment, the doping type of the first doping layer 112 is N-type. Furthermore, the doping element of the first doping layer 112 may be phosphorus. The N-type doped film layer is more advantageous in manufacturing and obtaining the light trap portion 1100 in the actual process.

[0043] As some examples of this embodiment, the material of the first doped layer 112 may include doped polysilicon.

[0044] As some examples of this embodiment, the thickness of the first doped layer 112 may be 100 nm to 400 nm.

[0045] As some examples of this embodiment, the second functional film 120 includes a second tunnel layer 121 and a second doping layer 122, which are sequentially stacked and arranged on a second region 102 of a crystalline silicon substrate 100. Here, the second tunnel layer 121 is for separating the second doping layer 122 from the crystalline silicon substrate 100, and the second tunnel layer 121 allows carriers to pass through the crystalline silicon substrate 100 while passivating it. The second doping layer 122 is for selectively collecting carriers.

[0046] As some examples of this embodiment, the material of the second tunnel layer 121 may be one or more selected from amorphous silicon, intrinsic amorphous silicon, hydrogenated amorphous silicon, intrinsic hydrogenated amorphous silicon, or silicon oxide.

[0047] As some examples of this embodiment, the thickness of the second tunnel layer 121 may be 1 nm to 3 nm.

[0048] As some examples of this embodiment, the doping type of the second doping layer 122 is P-type. Furthermore, the doping element of the second doping layer 122 may be boron.

[0049] As some examples of this embodiment, the material of the second doped layer 122 may include doped polysilicon.

[0050] As some examples of this embodiment, the thickness of the second doped layer 122 may be 100 nm to 400 nm.

[0051] As shown in Figure 1, in some examples of this embodiment, the first functional film 110 may further have at least one of a first passivation layer 113 and a first anti-reflective layer 114, the first passivation layer 113 and the first anti-reflective layer 114 being laminated on and covering the first dope layer 112.

[0052] As shown in Figure 1, in some examples of this embodiment, the second functional film 120 may further have at least one of the second passivation layer 123 and the second anti-reflective layer 124, the second passivation layer 123 and the second anti-reflective layer 124 being laminated on and covering the second dope layer 122.

[0053] As some examples of this embodiment, the first passivation layer 113 and the second passivation layer 123 can be an integrated structure, and the materials of the first passivation layer 113 and the second passivation layer 123 may include aluminum oxide. Furthermore, the entire layer composed of the first passivation layer 113 and the second passivation layer 123 may cover the isolation region 103.

[0054] As some examples of this embodiment, the first anti-reflective layer 114 and the second anti-reflective layer 124 can be an integrated structure, and the materials of the first anti-reflective layer 114 and the second anti-reflective layer 124 may include silicon hydride nitride, silicon hydride oxide, or a combination thereof. Furthermore, the overall layer composed of the first anti-reflective layer 114 and the second anti-reflective layer 124 may cover the isolation region 103.

[0055] As shown in Figure 1, in some examples of this embodiment, the back-contact solar cell may further include a front passivation layer 130. The front passivation layer 130 is laminated and arranged on one side of the crystalline silicon substrate 100 that is away from the first functional film 110 and the second functional film 120.

[0056] As some examples of this embodiment, the material of the front passivation layer 130 may include aluminum oxide.

[0057] As shown in Figure 1, in some examples of this embodiment, the back-contact solar cell may further include a front anti-reflective layer 140. The front anti-reflective layer 140 is laminated and arranged on one side of the front passivation layer 130 that is away from the crystalline silicon substrate 100, and the front anti-reflective layer 140 covers the front passivation layer 130.

[0058] As some examples of this embodiment, the material of the front anti-reflective layer 140 may include one or a combination of two types of silicon hydride nitride and silicon hydride oxide.

[0059] As shown in Figure 1, as some examples of this embodiment, the back-contact solar cell further includes a first electrode 150 and a second electrode 160, both of which are located on the back surface of the crystalline silicon substrate 100. The first electrode 150 is located in a first region 101 and is electrically connected to a first doping layer 112. The second electrode 160 is located in a second region 102 and is electrically connected to a second doping layer 122.

[0060] The present invention also provides a method for manufacturing a back-contact solar cell according to the above-described embodiment. Figure 4 is a schematic diagram of the process for manufacturing the back-contact solar cell. As shown in Figure 4, the manufacturing method includes steps S1 to S3.

[0061] Step S1: A first tunnel layer 111, a first dope layer 112, a first dope oxide layer 210, a second tunnel layer 121, and a second dope layer 122 are formed on the crystalline silicon substrate 100.

[0062] In some examples of this embodiment, a crystalline silicon material is used as the crystalline silicon substrate 100.

[0063] As some examples of this embodiment, the second tunnel layer 121 and the second dope layer 122 can be formed before the first tunnel layer 111 and the first dope layer 112. This further simplifies the subsequent steps of forming the light trap section 1100 in the first tunnel layer 111 and the first dope layer 112.

[0064] As some examples of this embodiment, the step of forming the second tunnel layer 121 and the second dope layer 122 includes depositing the second tunnel layer 121 and the second dope layer 122 on a semiconductor, and patterning the deposited second tunnel layer 121 and the second dope layer 122.

[0065] Figure 5 is a schematic cross-sectional diagram showing a crystalline silicon substrate 100 with a second tunnel layer 121 and a second doping layer 122 deposited on it. As shown in Figure 5, in this embodiment, the deposited second tunnel layer 121 and second doping layer 122 cover the first region 101, the second region 102, and the isolation region 103 on the back surface of the crystalline silicon substrate 100.

[0066] As some examples of this embodiment, the second tunnel layer 121 and the second dope layer 122 include the second tunnel layer 121 and the second dope layer 122 which are stacked and arranged sequentially.

[0067] As some examples of this embodiment, the step of forming the second tunnel layer 121 and the second dope layer 122 includes sequentially depositing the second tunnel layer 121, the silicon material layer, and the second dope oxide layer 220 by chemical vapor deposition, and then heating the second dope oxide layer 220 so that the doping elements in it diffuse into the silicon material layer to form the second dope layer 122. Here, the chemical vapor deposition method may specifically be LPCVD or PECVD.

[0068] For example, in this example, the material of the second doped oxide layer 220 may be borosilicate glass. By heating, boron in the borosilicate glass can be diffused into the silicon material layer to form P-type doped polysilicon, that is, it can become the second doped layer 122.

[0069] As some other examples of this embodiment, the step of forming the second tunnel layer 121 and the second dope layer 122 includes sequentially depositing the second tunnel layer 121 and the second dope oxide layer 122 by chemical vapor deposition. Here, the chemical vapor deposition method may specifically be LPCVD or PECVD. The second tunnel layer 121 and the second dope layer 122 can be formed by depositing them one after the other in the same deposition chamber. After depositing the second dope layer 122, one layer of the second dope oxide layer 220 may be deposited.

[0070] To make it clear, the deposited second tunnel layer 121 and second dope layer 122 not only cover the second region 102 on the back surface of the crystalline silicon substrate 100, but also extend to cover the first region 101 and the isolation region 103. In some examples of this embodiment, after the second tunnel layer 121 and second dope layer 122 have been deposited and formed, the second tunnel layer 121 and second dope layer 122 are further patterned so that the second tunnel layer 121 and second dope layer 122 outside the second region 102 are removed. In this embodiment, the pre-formed second dope oxide layer 220 can also be used as a mask in the subsequent patterning process.

[0071] Figure 6 is a schematic diagram of the structure shown in Figure 5, in which the second tunnel layer 121 and the second doping layer 122 located outside the second region 102 have been removed. As shown in Figure 6, only the second tunnel layer 121 and the second doping layer 122 located in the second region 102 remain, and the first region 101 and the isolation region 103 of the crystalline silicon substrate 100 are exposed from the openings of the second tunnel layer 121 and the second doping layer 122.

[0072] As some examples of this embodiment, a method for pattern processing the second tunnel layer 121 and the second dope layer 122 is to first melt and remove the second dope oxide layer 220 on the first region 101 and the separation region 103 using a target laser 310, and then etch and remove the second dope layer 122 and the second tunnel layer 121 exposed from the region melted by the target laser 310 using an alkaline solution.

[0073] Furthermore, in the process of etching the second dope layer 122 and the second tunnel layer 121 with an alkaline solution, it is possible to ensure that a second doped oxide layer 220 with a thickness of 6 nm or more remains in the second region 102 by controlling the etching time, etc. This allows for a certain degree of protection to be provided to the second tunnel layer 121 and the second dope layer 122 in subsequent processes.

[0074] As shown in Figure 6, the second tunnel layer 121 and the second dope layer 122 located in the first region 101 and the separation region 103 are removed, leaving only the second tunnel layer 121 and the second dope layer 122 located in the second region 102, as well as the second dope oxide layer 220.

[0075] Figure 7 is a schematic diagram of a structure in which the first tunnel layer 111 and the first doping layer 112 are stacked based on the structure shown in Figure 6. As shown in Figure 7, in this example, the first tunnel layer 111 and the first doping layer 112 cover the first region 101 and the isolation region 103 on the back surface of the crystalline silicon substrate 100, and the first tunnel layer 111 and the first doping layer 112 extend to cover the second tunnel layer 121 and the second doping layer 122 as well.

[0076] As some examples of this embodiment, the first tunnel layer 111 and the first dope layer 112 include the first tunnel layer 111 and the first dope layer 112 which are stacked and arranged sequentially.

[0077] As some examples of this embodiment, the step of forming the first tunnel layer 111 and the first dope layer 112 includes sequentially depositing the first tunnel layer 111, the silicon material layer and the first dope oxide layer 210 by chemical vapor deposition, and then heating to form the first dope layer 121 so that the doping elements in the first dope oxide layer 210 diffuse into the silicon material layer. Here, the chemical vapor deposition method may specifically be LPCVD or PECVD.

[0078] For example, in this example, the material of the first doped oxide layer 210 may be phosphate glass. By heating, phosphorus in the phosphate glass can be diffused into the silicon material layer to form N-type doped polysilicon, that is, it can become the first doped layer 112.

[0079] As some other examples of this embodiment, the step of forming the first tunnel layer 111 and the first dope layer 112 includes sequentially depositing the first tunnel layer 111 and the first dope layer 112 by chemical vapor deposition. Here, the chemical vapor deposition method may specifically be plasma-enhanced chemical vapor deposition (PECVD). The first tunnel layer 111 and the first dope layer 112 can be formed by depositing them one after the other in the same deposition chamber. After depositing the first dope layer 112, one layer of the first doped oxide layer 210 may be deposited.

[0080] Step S2: A portion of the first doped oxide layer 210 is removed from the light trapping area 301 to expose the first doped layer 112 located beneath it.

[0081] To understand this, the exposed first dope layer 112 can be preferentially corroded in the subsequent alkaline solution corrosion process to form light trap valleys 1102, while some of the first dope layer 112 that is still shielded by the first dope oxide layer 210 can be corroded relatively slowly to form light trap peaks 1101.

[0082] In this embodiment, the step of removing a portion of the first doped oxide layer 210 from the light trapping region 301 includes scanning the light trapping region 301 with a target laser 310. During the scanning process, the light spot of the target laser 310 has a high-energy region 311 and a low-energy region 312, and the power density of the high-energy region 311 is >0.25 J / cm². 2 Therefore, the power density in the low-energy region 312 is ≤0.25 J / cm². 2 Alternatively, the target laser 310 is controlled to scan only a local area of ​​the light trapping region 301 during the scanning process.

[0083] As an example of this embodiment, the optical spot size of the target laser 310 is 50 μm to 300 μm.

[0084] In this embodiment, when the target laser 310 scans the light trap processing area 301, the first doped oxide layer 210 has a high melting point and high light transmittance, so the target laser 310 actually acts mainly on the first doped layer 112. After the first doped layer 112 melts, the first doped oxide layer 210 above it is destroyed, thereby achieving the objective of removing the first doped oxide layer 210. By setting the optical spot energy distribution of the target laser 310 (i.e., having a high-energy region 311 and a low-energy region 312), selective removal of the first doped oxide layer 210 can be achieved. Alternatively, by changing the optical spot shape of the target laser 310 located in the light trap processing area 301, the target laser 310 will scan only a local area of ​​the light trap processing area 301, further achieving selective removal of the first doped oxide layer 210.

[0085] Figure 8 is a schematic diagram showing the control of the energy density distribution of the light spot of the target laser 310. As shown in Figure 8, in some examples of this embodiment, in the process of scanning the light trapping area 301 with the target laser 310, the light spot of the target laser 310 has a high-energy region 311 and a low-energy region 312, and the power density of the high-energy region 311 is >0.25 J / cm². 2 Therefore, the power density in the low-energy region 312 is ≤0.25 J / cm². 2 Therefore, as can be understood, in Figure 8, the target laser 310 is controlled to move intermittently along the light trapping processing region 301, so that the first doped oxide layer 210 can be removed by the target laser 310 in the high-energy region 311, but it is difficult to remove the first doped oxide layer 210 by the target laser 310 in the low-energy region 312, and in this way, localized removal of the first doped oxide layer 210 is achieved.

[0086] As some examples of this embodiment, the power density in the high-energy region 311 of the target laser 310 is 0.25 J / cm². 2 ~0.5J / cm 2That is. For example, the power density in the high energy region 311 of the target laser 310 is 0.25 J / cm 2 、0.28 J / cm 2 、0.3 J / cm 2 、0.32 J / cm 2 、0.35 J / cm 2 、0.38 J / cm 2 、0.4 J / cm 2 、0.45 J / cm 2 、0.5 J / cm 2 ; or the power density of the target laser 310 may be a value between any two of the above power densities. According to the target laser 310 with such a power density, it is more advantageous for controlling the ablation rate of the first tunnel layer 111 and the first doped layer 112 by the target laser 310.

[0087] As some examples of this embodiment, the power density in the low energy region 312 of the target laser 310 is 0.13 J / cm 2 ~0.25 J / cm 2 . For example, the power density in the low energy region 312 of the target laser 310 is 0.13 J / cm 2 、0.15 J / cm 2 、0.17 J / cm 2 、0.19 J / cm 2 、0.2 J / cm 2 、0.22 J / cm 2 ; or the power density of the low energy region 312 of the target laser 310 may be a value between any two of the above power densities.

[0088] Figure 9 is a structural schematic diagram showing the control of the scanning area of the target laser 310. As shown in Figure 9, as some other examples of this embodiment, during the scanning process, the target laser 310 is controlled to scan only a local area of the light trap processing area 301. <UNK>

[0089] As shown in Figure 9, in this embodiment, during the scanning process, the light spot of the target laser 310 can take on a shape such as a square, rectangle, or rhombus. By rotating the light spot of the target laser 310 so that the target laser 310 falling into the light trap processing area 301 takes on a triangular shape, the target laser 310 can only irradiate a portion of the light trap processing area 301 during the scanning process.

[0090] To make it clear, the scanning method using the target laser 310 described above is only one method for removing a portion of the first doped oxide layer 210. In actual processes, there are various methods for selectively removing a portion of the first doped oxide layer 210 from the light-trapped processing area 301. For example, a portion of the first doped oxide layer 210 can be removed by damaging its surface through machining. Alternatively, a portion of the first doped oxide layer 210 can be removed by chemical corrosion, such as by spot coating or screen printing an corrosive agent onto the surface of the first doped oxide layer 210.

[0091] In some examples of this embodiment, in the step of forming a first tunnel layer 111, a first dope layer 112, and a first doped oxide layer 210, the formed first tunnel layer 111, first dope layer 112, and first doped oxide layer 210 extend and are located in a separation region 103. The manufacturing method further includes the step of dissolving and removing the first doped oxide layer 210 located in the separation region 103 using a separation region laser.

[0092] For example, the first doped oxide layer 210 in the separated region 103 can be melted and removed using a separated region laser, and during the melting process, the separated region laser can be switched to a target laser 310 to irradiate the first doped oxide layer 210 in the light-trapped processing region 301. Here, the target laser 310 and the separated region laser can use the same laser source or different laser sources.

[0093] As some examples of this embodiment, the power density of the separation region laser is 0.25 J / cm². 2 ~0.5J / cm 2 For example, the power density of a separation-region laser is 0.25 J / cm². 2 , 0.28 J / cm² 2 , 0.3 J / cm 2 , 0.32 J / cm² 2 , 0.35 J / cm 2 , 0.38 J / cm² 2 , 0.4 J / cm 2 , 0.45 J / cm 2 , 0.5 J / cm 2 Alternatively, the power density of the separation region laser may be between any two of the above power densities.

[0094] As some examples of this embodiment, in the process of melting with a separation region laser, the separation region laser scans along the separation region 103, and during the scanning process, the overlap rate of the light spots of two adjacent separation region lasers is 20% to 60%, that is, there is an overlap of 20% to 60% of the irradiation area of ​​the light spots of two adjacent separation region lasers, which makes it possible to remove the first tunnel layer 111 and the first dope layer 112 as completely and uniformly as possible.

[0095] Here, the purpose of melting with the separation region laser is to remove the first doped oxide layer 210 located in the separation region 103. On the other hand, the purpose of irradiating with the target laser 310 is to perform a localized removal treatment on the first doped oxide layer 210 located in the light-trapped treatment region 301, thereby forming light-trapped valleys 1102 and light-trapped peaks 1101 during the subsequent alkaline solution corrosion process.

[0096] As some examples of this embodiment, in the step of melting the first tunnel layer 111 and the first dope layer 112 with a separated region laser, the first doped oxide layer 210, the first tunnel layer 111, and the first dope layer 112 in the second region 102 are also melted together.

[0097] Step S3: The first doped oxide layer 210, the first doped layer 112, and the first tunnel layer 111 are corroded with an alkaline solution to form a light trap section 1100.

[0098] Figure 10 is a schematic cross-sectional view of the structure shown in Figure 7 after corrosion with an alkaline solution. As shown in Figure 10, in the process of corrosion of the first doped oxide layer 210, the first doped layer 112, and the first tunnel layer 111 with an alkaline solution, only a portion of the first doped oxide layer 210 in the light trap treatment area 301 is removed. As a result, the exposed first doped layer 112 and the first tunnel layer 111 corrode relatively quickly, while the unexposed first doped layer 112 and the first tunnel layer 111 corrode relatively slowly, thereby forming light trap valleys 1102 and / or light trap peaks 1101.

[0099] In this embodiment, since the N-type first doping layer 112 is susceptible to corrosion by alkaline solutions, manufacturing a light trap structure from the N-type doped first doping layer 112 has the advantage of being less difficult to process. In other embodiments, a light trap structure can also be manufactured using the P-type doped first doping layer 112.

[0100] As some examples of this embodiment, in the step of corroding the first tunnel layer 111 and the first dope layer 112 with an alkaline solution, a flocking agent is used as the alkaline solution, and at the same time, the front surface of the crystalline silicon substrate 100 is flocked with the flocking agent. The flocking agent can be an alkaline flocking agent that forms a flocked surface structure, and it may contain sodium hydroxide and flocking additives. By using a flocking agent as the alkaline solution, it is possible not only to form the light trap portion 1100, but also to form a flocked surface structure on both the surface of the separation region 103 of the crystalline silicon substrate 100 and the front surface of the crystalline silicon substrate 100.

[0101] During the process of forming the light trap section 1100, the remaining first doped oxide layer 210 and second doped oxide layer 220 can be removed, that is, the first tunnel layer 111 and first doped layer 112 in the first region 101, and the second tunnel layer 121 and second doped layer 122 located in the second region 102 can be exposed. In addition, the above film layer deposition processes may also cause problems with stray deposition, and the process of corrosion with an alkaline solution can remove the material of stray deposition all at once.

[0102] As some examples of this embodiment, the process may further include forming a light trap portion 1100 by corrosion with an alkaline solution, followed by depositing a first passivation layer 113, a second passivation layer 123, and a front passivation layer 130.

[0103] As some examples of this embodiment, the process may further include depositing a first passivation layer 113, a second passivation layer 123, and a front passivation layer 130, followed by depositing a first anti-reflective layer 114, a second anti-reflective layer 124, and a front anti-reflective layer 140.

[0104] As some examples of this embodiment, the process may further include the steps of forming a first passivation layer 113 and a second passivation layer 123, followed by the production of a first electrode 150 and a second electrode 160. Methods for producing the first electrode 150 and the second electrode 160 include screen printing, electroplating, and PVD (Physical Vapor Deposition).

[0105] By following the above steps S1 to S3, a back-contact solar cell according to the present invention can be formed.

[0106] Furthermore, the present invention also provides a photovoltaic assembly comprising a back-contact solar cell described in any one embodiment, or a back-contact solar cell manufactured by a method for manufacturing a back-contact solar cell described in any one embodiment.

[0107] Furthermore, the present invention also provides the following more specific examples and comparative examples to further illustrate specific forms for carrying out the invention and the beneficial effects associated therewith.

[0108] Example 1 Crystalline silicon was used as the substrate, and on its back surface, a 2 nm thick silicon dioxide layer was deposited as a second tunnel layer by LPCVD. Subsequently, a 300 nm thick intrinsic amorphous silicon layer and a 50 nm thick borosilicate glass layer were deposited, and a high-temperature annealing treatment was performed to form a P-type doped polysilicon as the second doped layer.

[0109] The borosilicate glass corresponding to the first region and the isolation region was etched with a laser, and then the second doped layer and the second tunnel layer corresponding to the first region and the isolation region were corroded with an alkaline solution until the crystalline silicon substrate was exposed.

[0110] On the back surface of the crystalline silicon substrate, a 2 nm thick silicon dioxide layer was deposited as the first tunnel layer by LPCVD, followed by the deposition of a 300 nm thick intrinsic amorphous silicon layer and a 50 nm thick phosphate glass layer. High-temperature annealing was then performed to form an N-type doped polysilicon layer as the first doped layer.

[0111] The separation region laser was used to scan and melt the second region and the separation region according to a pre-set pattern, and then, in a corresponding manner, the first region immediately adjacent to the separation region was melted by the target laser. Here, both the target laser and the separation region laser light spots exhibited a square shape. The target laser irradiated onto the first region had a high-energy region and a low-energy region, with a power density of 0.3 J / cm² in the high-energy region. 2 The power density in the low-energy region is 0.15 J / cm². 2The target laser was irradiated once every 100 μm along the boundary between the separation region and the first region. With each irradiation, the laser extended 25 μm along the boundary while extending 15 μm into the first region. The power density of the separation region laser was 0.4 J / cm². 2 The energy of the separation region laser was uniformly distributed.

[0112] The stray deposits on the surface of the crystalline silicon substrate were removed, and the front surface, isolated region, and area scanned by the target laser were treated with a flocculating agent. A flocculated surface structure was formed on the front surface and isolated region of the crystalline silicon substrate, and light-trapped valleys and light-trapped peaks were formed in the area scanned by the target laser.

[0113] A passivation layer made of aluminum oxide and an anti-reflective layer made of silicon hydride nitride were deposited on both the front and back surfaces of the crystalline silicon substrate, respectively, and the positive and negative electrodes were screen printed on the back surface of the crystalline silicon substrate.

[0114] Comparative Example 1 Comparative Example 1 is almost identical to Example 1, with the main difference being that Comparative Example 1 uses only separated-region laser scanning, does not use target laser scanning, and does not form a light trap section.

[0115] Test 1: The surface features of the separation region of Example 1 and the vicinity of its first region were observed using a scanning electron microscope. The observation results are shown in Figures 11 to 13. Figure 11 is a local enlarged plan view including one light trap section according to Example 1, Figure 12 is a local reduced plan view including multiple light trap sections according to Example 1, and Figure 13 is a schematic cross-sectional structure diagram according to Example 1.

[0116] Test 2: The electrical characteristics of each of the above-described embodiments were measured. The specific results are shown in Table 1.

[0117] [Table 1] As shown in Figure 11, in the back-contact solar cell manufactured in Example 1, a flocked surface structure is formed on the surface of the isolation region 103. A first region is located on one side of the isolation region 103, and a film layer, which is a passivation contact film consisting of an N-type doped polysilicon and a silicon dioxide layer, is located in the first region. A light trap portion 1100 is formed in the passivation contact film, and a light trap valley 1102 and a plurality of continuous light trap peaks 1101 are arranged in the light trap portion 1100.

[0118] As shown in Figure 12, the white dotted line in Figure 12 indicates the baseline of the separation region 103. The GetData software's automatic recognition function obtained 183 points located at the first boundary 1001 in Figure 12, obtained the distance of each of these 183 points from the baseline of the separation region 103, and calculated the variance, which was 52.85. The GetData software then obtained 183 points located at the second boundary 1002 in Figure 12, obtained the distance of each of these 183 points from the baseline of the separation region 103, and calculated the variance, which was 27.27. Therefore, the variance of the first boundary 1001 is clearly larger than the variance of the second boundary 1002. In particular, it should be explained that when the GetData software automatically recognizes points on the first and second boundaries, as long as the points are uniformly distributed in the direction along the baseline of the separation region, they can represent the degree of deviation of the first or second boundary with respect to the baseline of the separation region, and the number of points on the first boundary does not have to match the number of points on the second boundary. Typically, a ratio of 0.5 to 2 for the number of points on the first boundary to the number of points on the second boundary is considered a reasonable method of point selection.

[0119] As shown in Figure 13, the height difference between the bottom edge of the light trap section 1100 and the top surface of the first functional membrane 110 in Figure 13 is 3.92 μm, and the separation region 103 has a flocked surface structure, and the height difference between the bottom edge of the flocked surface structure and the top surface of the first functional membrane 110 is 2.85 μm. Thus, it has been stated that the height difference between the bottom edge of the light trap section 1100 and the top surface of the first functional membrane 110 is greater than the height difference between the bottom edge of the separation region 103 and the top surface of the first functional membrane 110.

[0120] As shown in Table 1, in Comparative Example 1, a conventional method was employed and irradiation with a target laser was not used, so a light trap section was not formed. Compared to Comparative Example 1, in Example 1, irradiation with a target laser was used and a light trap section was formed, and both the short-circuit current density and conversion efficiency of Example 1 were clearly improved.

[0121] It should be noted that the above-described embodiments are for illustrative purposes only and do not limit the present invention.

[0122] It is important to understand that, unless otherwise specified herein, there are no strict restrictions on the order in which the processes are performed, and these processes may be performed in any other order. Furthermore, at least part of a process in the manufacturing process may include multiple sub-processes or stages, and these sub-processes or stages do not necessarily have to be completed at the same time, but may be performed at different times. The order in which these sub-processes or stages are performed is not necessarily sequential, and they may be performed sequentially or alternately with other processes or at least part of the sub-processes or stages of other processes.

[0123] Each embodiment in this specification is described in a progressive manner, with each embodiment focusing on the differences from other embodiments, and the same or similar parts between embodiments should be referenced to one another.

[0124] The technical features in the embodiments described above can be combined in any way, and for the sake of brevity, not all possible combinations of the technical features in the embodiments described above have been described. However, all such combinations of technical features should be considered to be within the scope described herein, as long as they do not contradict each other.

Claims

1. Back-contact solar cells, A crystalline silicon substrate having a first region, a second region and a separation region arranged on its back surface, wherein the separation region is positioned between the first region and the second region, and the first region and the second region are separated from each other via the separation region. A first functional film comprising a first tunnel layer and a first dope layer sequentially stacked and arranged in the first region, wherein the first functional film has a light trap portion immediately adjacent to the isolation region, and at least one of a light trap valley and a light trap peak is arranged in the light trap portion, wherein, along the thickness direction adjacent to the crystalline silicon substrate, the diameter of the light trap valley is reduced in the direction from the tank opening to the tank bottom, and the side walls of the light trap peak are expanded outward in the direction from the top to the bottom edge of the first functional film, A back-contact solar cell characterized by comprising a second functional film including a second tunnel layer and a second dope layer sequentially stacked and arranged in the second region, wherein the dope type of the second dope layer and the first dope layer are reversed.

2. The back-contact solar cell according to claim 1, characterized in that the light trap section has a plurality of light trap peaks arranged in a continuous manner, and the bottom ends of the side walls of two adjacent light trap peaks are connected to each other.

3. The back-contact solar cell according to claim 1, characterized in that the first functional film has a first boundary immediately adjacent to the isolation region, the second functional film has a second boundary immediately adjacent to the isolation region, and the variation dispersion of the first boundary is greater than the variation dispersion of the second boundary.

4. The back-contact solar cell according to claim 3, characterized in that the value of the variation dispersion of the first boundary is 30 to 100.

5. The back-contact solar cell according to claim 1, characterized in that the height difference between the edge of the light trap portion closest to the crystalline silicon substrate and the ceiling surface of the first functional film is 0.5 μm to 6 μm.

6. The back-contact solar cell according to claim 5, characterized in that the height difference between the edge of the light trap portion closest to the crystalline silicon substrate and the ceiling surface of the first functional film is 3 μm to 6 μm.

7. The back-contact solar cell according to claim 1, characterized in that the surface of the isolation region of the crystalline silicon substrate has a flocked surface structure, and the height difference between the bottom edge of the light trap portion and the top surface of the first functional film is greater than the height difference between the bottom edge of the adjacent isolation region and the top surface of the first functional film.

8. The back-contact solar cell according to any one of claims 1 to 7, characterized in that the doping type of the first doping layer is N-type and the doping type of the second doping layer is P-type.

9. The first functional film further includes at least one of a first passivation layer and a first anti-reflective layer laminated and / or arranged on the first dope layer, The back-contact solar cell according to any one of claims 1 to 7, characterized in that the second functional film further comprises at least one of a second passivation layer and a second anti-reflective layer laminated and arranged on the second dope layer.

10. A method for manufacturing a back-contact solar cell according to claim 1, The process involves sequentially forming the second tunnel layer and the second dope layer in the second region of the crystalline silicon substrate, and sequentially forming the first tunnel layer, the first dope layer, and the first doped oxide layer in the first region of the crystalline silicon substrate. The first doped oxide layer has a light trapping treatment area immediately adjacent to the separation area, and the process involves removing a portion of the first doped oxide layer in the light trapping treatment area to expose the first doped layer located below, A method for manufacturing a back-contact solar cell, comprising the step of corroding the first doped oxide layer, the first doped layer, and the first tunnel layer with an alkaline solution to form the light trap portion.

11. The step of removing a portion of the first doped oxide layer in the light trapping region includes scanning the light trapping region with a target laser, During the scanning process, the optical spot of the target laser has a high-energy region and a low-energy region, and the power density of the high-energy region is >0.25 J / cm². ２ Therefore, the power density in the low-energy region is ≤0.25 J / cm². ２ is, or, The method for manufacturing a back-contact solar cell according to claim 10, characterized in that the target laser is controlled to scan only a local area of ​​the light trapping processing region during the scanning process.

12. In the step of depositing the first tunnel layer and the first dope layer on the crystalline silicon substrate, the first tunnel layer, the first dope layer and the first dope oxide layer extend and are deposited in the separation region. The method for manufacturing a back-contact solar cell according to any one of claims 10 to 11, further comprising the step of dissolving and removing the first doped oxide layer located in the separation region using a separation region laser.

13. A method for manufacturing a back-contact solar cell according to any one of claims 10 to 11, characterized in that, in the step of corroding the first tunnel layer and the first dope layer with an alkaline solution, a flocculating agent is used as the alkaline solution, and a flocculating treatment is performed simultaneously on the front and back surfaces of the crystalline silicon substrate using the flocculating agent.

14. A photovoltaic assembly, A back-contact solar cell according to any one of claims 1 to 7, or A photovoltaic assembly characterized by including a back-contact solar cell manufactured by the method for manufacturing a back-contact solar cell according to any one of claims 10 to 11.

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