Rear contact solar cell, rear contact solar cell assembly and photovoltaic power generation system

Abstract

The present application applies to the field of solar cell technology and provides a back contact solar cell, a back contact solar cell assembly, and a photovoltaic power generation system. A grooved region and a non-grooved region are alternately arranged on the light-shielding surface of a silicon chip. At a predetermined location of the grooved region, a first doping layer has an extension extending over the grooved region, and a second doping layer has a wrapping portion covering and re-bonding to a first surface of the extension portion. No silicon wafer portion is provided on the side where the wrapping portion re-bonds to the first surface, and the edge re-bonding occurring in the boundary region between them has a relatively narrow range of influence, thereby effectively improving efficiency with a higher fill rate. Meanwhile, the re-bonding between the wrapping portion and the first surface of the extension portion can provide a specific re-bonding area to increase the current during electrical injection and to improve repair efficiency and effectiveness during subsequent repair of the back contact solar cell.

Description

Technology Field

[0001] Priority Information

[0002] The present application claims priority and interest in patent applications No. 202310282218.X and No. 202320570099.3 filed with the National Intellectual Property Administration of China on March 16, 2023, and patent applications No. 202321268949.0 and No. 202310583236.1 filed with the National Intellectual Property Administration of China on May 23, 2023, the full text of which is incorporated herein by reference.

[0003] Technology field

[0004] This application relates to the field of solar cell technology, in particular to back-contact solar cells, back-contact solar cell assemblies, and photovoltaic systems. Background Technology

[0005] Currently, among solar cells, back-contact solar cells are a type of cell in which both the emitter and base contact electrodes are positioned on the rear (non-light-receiving) side. The light-receiving side of the cell, which is not obstructed by any metal electrodes, effectively increases the short-circuit current.

[0006] In the solutions of existing technologies, the back surface of a back contact solar cell is typically a flat surface in which P and N regions are alternately arranged and at least a portion of the P and N regions intersect. In such cases, severe edge recombination occurring at the boundary of the P / N regions on the back surface of the back contact solar cell has a wide range of influence, which affects the electrical performance of the cell, particularly the filling factor, thereby degrading the efficiency of the back contact solar cell. The problem to be solved

[0007] The present application provides a back contact solar cell, a back contact solar cell assembly, and a photovoltaic power generation system, and aims to solve the technical problem of reducing the range of influence of recombination in the boundary region of the P / N area on the shading surface of the back contact solar cell, improving the cell's fill factor, and further improving conversion efficiency. means of solving the problem

[0008] The present application is implemented as follows. In an embodiment of the present application, the back contact solar cell comprises the following:

[0009] A silicon wafer, wherein the silicon wafer has a light-receiving face and a shady face facing each other, and the shady face is provided with a plurality of groove areas and a plurality of non-groove areas spaced apart, and the non-groove areas and the groove areas are alternately arranged;

[0010] A first doping layer, wherein the first doping layer is laminated over the non-groove region, and at a predetermined position of the groove region, the first doping layer has an extension extending over the groove region, and the extension has a first surface facing the groove region and a second surface moving away from the groove region;

[0011] A second doping layer, wherein the second doping layer is laminated within the groove region and has a polarity opposite to that of the first doping layer, and at a predetermined position, the second doping layer has a wrapping portion that extends along the sidewall surface of the groove region and covers the first surface, and the wrapping portion recombines with the first surface.

[0012] In addition, the present application provides a back contact solar cell comprising the following:

[0013] A silicon wafer, wherein the light-shielding surface of the silicon wafer comprises a plurality of alternately arranged first regions and second regions, and a slot is formed in the second region;

[0014] A first doping layer, wherein the first doping layer is located on the first region, and at a predetermined position of the slot, the first doping layer comprises a first portion located on the first region and a second portion extending over the slot; and

[0015] A second doping layer, wherein the second doping layer is disposed in the slot, and at the predetermined position, the second doping layer covers the bottom surface and side of the slot, wraps around the surface facing the slot and the side of the second portion, and the second doping layer is re-bonded to the surface of the second portion facing the slot.

[0016] The present application also provides a rear contact solar cell assembly comprising a rear contact solar cell as described in any one of the above items.

[0017] The present application also provides a photovoltaic power generation system comprising the aforementioned rear contact solar cell assembly. Effects of the invention

[0018] In the back contact solar cell, assembly, and photovoltaic power generation system of the present application, on the one hand, due to the presence of a groove region, an extension, and a wrapping region, the wrapping region recombines with the first surface of the extension, and one side of the recombination region between the wrapping region and the extension is a groove region without any part of the silicon wafer, and the edge recombination created by the boundary region between them affects only the silicon wafer on one side of the groove region, and the range of influence is narrow, thereby effectively reducing the number of carriers affected by the silicon wafer by narrowing the range of the silicon wafer radiating from the boundary region and increasing the fill factor, thereby improving the electrical performance and efficiency of the back contact solar cell. On the other hand, at a predetermined location, the recombination between the wrapping region and the first surface of the extension provides a specific recombination region that increases the current during electrical injection and improves the repair efficiency and effectiveness during subsequent repair of the back contact solar cell. Meanwhile, the side of the extension not covered by the wrapping region can prevent the very large recombination region between the extension and the wrapping region from affecting the cell efficiency.

[0019] Some of the additional aspects and advantages of the present application will be provided below, and some may become clear or understood through the practice of the present application. Brief explanation of the drawing

[0020] FIG. 1 is a schematic diagram of a module of a photovoltaic power generation system provided in an embodiment of the present application. FIG. 2 is a schematic diagram of a module of a back-contact solar cell assembly provided in an embodiment of the present application. FIG. 3 is a schematic diagram of a planar structure of a back-contact solar cell provided in Example 1 of the present application. FIG. 4 is a schematic cross-sectional diagram of IV-IV along the back-contact solar cell of FIG. 3. FIG. 5 is a schematic cross-sectional diagram of a back-contact solar cell of the prior art. FIG. 6 is another schematic cross-sectional diagram of IV-IV along the back-contact solar cell of FIG. 3. FIG. 7 is another schematic cross-sectional diagram of IV-IV along the back-contact solar cell of FIG. 3. FIG. 8 is another schematic cross-sectional diagram of IV-IV along the back-contact solar cell of FIG. 3. FIG. 9 is another schematic cross-sectional diagram of IV-IV along the back-contact solar cell of FIG. 3. FIG. 10 is another schematic cross-sectional diagram of IV-IV along the back-contact solar cell of FIG. 3. FIG. 11 is a back-contact solar cell provided in Example 2 of the present application. This is another schematic diagram of the planar structure. Fig. 12 is another schematic cross-sectional diagram of XII-XII along the back contact solar cell of Fig. 11. Fig. 13 is another schematic cross-sectional diagram of XII-XII along the back contact solar cell of Fig. 11. Fig. 14 is another schematic cross-sectional diagram of XII-XII along the back contact solar cell of Fig. 11. Fig. 15 is another schematic cross-sectional diagram of the back contact solar cell along the XII-XII section of Fig. 11. Specific details for implementing the invention

[0021] To make the purpose, technical plan, and benefits of the present application clearer, the present application will be described in more detail with reference to the accompanying drawings and examples. Examples of the examples are illustrated in the accompanying drawings, wherein identical or similar labels indicate identical or similar elements or elements having identical or similar functions. The examples described below with reference to the accompanying drawings are illustrative and are intended only to explain the present application and should not be understood as limiting the present application. Furthermore, the specific examples described herein should be understood as illustrative rather than limiting the present application.

[0022] In the description of this application, the terms “length,” “width,” “up,” “down,” “top,” “bottom,” “horizontal,” and “vertical” indicate orientations or positional relationships based on the orientations or positional relationships depicted in the accompanying drawings. These terms are provided for convenience only to simply describe this application and do not indicate or imply that the mentioned devices or elements must have a specific orientation or be configured and operated in a specific orientation, and therefore should not be understood as limiting this application.

[0023] Furthermore, terms such as "first" and "second" are for illustrative purposes only and should not be understood as indicating or implying the relative importance or number of the technical features mentioned. Accordingly, the features defined as "first" and "second" may explicitly or implicitly include at least one or more features. In the description of this application, the meaning of "plural" refers to two or more unless otherwise specified.

[0024] In the description of this application, unless otherwise specified or limited, the terms “installed,” “connected,” and “connection” should be understood broadly. It should be noted that, for example, they may be fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections, or mutual connections; direct connections or indirect connections through an intermediate medium; and internal connections or interaction relationships between two elements. Those skilled in the art will understand the specific meaning of the above terms in this application according to the specific circumstances.

[0025] In this application, unless otherwise specified and limited, a first feature located "above" or "below" a second feature may include direct contact between the first feature and the second feature, or direct contact between the first feature and the second feature through an additional feature between the two features. Additionally, a first feature located "over," "above," and "on" a second feature may include the first feature being directly above and diagonally above the second feature, or simply indicate that the first feature is horizontally higher than the second feature. A first feature located "below," "beneath," and "under" a second feature may include the first feature being directly below and diagonally below the second feature, or simply indicate that the horizontal height of the first feature is lower than the horizontal height of the second feature.

[0026] The following disclosure provides various embodiments or examples for implementing various features of the present application. The components and arrangements of specific examples are described below for the sake of simplicity of the disclosure of the present application. Of course, this is merely illustrative and is not intended to limit the present application. Additionally, the present application may repeat reference numbers and / or letters in various examples. Such repetition is for brevity and clarity and does not imply, by itself, the relationship between the various embodiments and / or configurations discussed. Furthermore, while the present application provides examples of various specific processes and materials, those skilled in the art may recognize scenarios for the application of other processes and / or the use of other materials.

[0027] Example 1

[0028] Referring to FIG. 1 and FIG. 2, in an embodiment of the present application, the photovoltaic power generation system (1000) may include a rear contact solar cell assembly (200) (rear contact solar cell assembly), and in an embodiment of the present application, it may further include a plurality of rear contact solar cells (100) (rear contact solar cell assembly).

[0029] A plurality of rear contact solar cells (100) within a rear contact solar cell assembly (200) may be sequentially connected in series to form a plurality of cell strings. Each cell string may be connected in series, in parallel, or in combination to obtain a current output. For example, the cells may be connected by welding strips to form cell strings, and the cell strings may be connected via busbars. In some embodiments, the cell strings may form a cell array, and this cell array is packaged together through a front plate, a front adhesive film, a rear adhesive film, and a back plate to form a rear contact solar cell assembly (200).

[0030] Referring to FIGS. 3 and 4, in an embodiment of the present application, a back contact solar cell (100) may include a silicon wafer (10), a first doping layer (20), and a second doping layer (30).

[0031] A silicon wafer (10) has a light-receiving surface (11) and a light-blocking surface (12) facing each other, and the light-blocking surface (12) is provided with a plurality of grooved regions (121) and a plurality of non-grooved regions (122) arranged at regular intervals, and the non-grooved regions (122) and grooved regions (121) are arranged alternately.

[0032] Specifically, as illustrated in FIG. 3, the groove region (121) and the non-groove region (122) may be alternately arranged along the lateral direction of the silicon wafer (10). In the illustrated embodiment, the edge region of the silicon wafer (10) is the non-groove region (122), and both the groove region (121) and the non-groove region (122) extend along the longitudinal direction of the silicon wafer (10). The groove region (121) and the non-groove region (122) may be formed through a plurality of slots spaced apart in the silicon wafer (10), the formed slots correspond to the groove region (121), and the area between two adjacent slots corresponds to the non-groove region (122).

[0033] As illustrated in FIGS. 3 and 4, the first doping layer (20) may be laminated over a non-grooved region (122). At a predetermined location (123) of the grooved region (121), the first doping layer (20) has an extension (21) extending over the grooved region (121), and this extension (21) has a first surface (211) facing the grooved region (121) and a second surface (212) facing away from the grooved region (121).

[0034] The second doping layer (30) may be laminated within the groove region (121) and has opposite polarity to the first doping layer (20). Specifically, the first doping layer (20) may be an N-type doping layer and the second doping layer (30) may be a P-type doping layer, or vice versa, and as long as the two doping layers have opposite polarity, they are not limited in this specification. At a predetermined location (123) of the groove region (121), the second doping layer (30) has a wrapping portion (31) that extends along the sidewall surface of the groove region (121) and covers the first surface (211) of the extension portion (21). The wrapping portion (31) re-bonds with the first surface (211) of the extension portion (21).

[0035] In the back contact solar cell (100), back contact solar cell assembly (200), and photovoltaic power generation system (1000) of the embodiment of the present application, a plurality of grooved regions (121) and non-grooved regions (122) are alternately arranged on the light-shielding surface of the silicon chip. At a predetermined position (123) of the grooved region (121), the first doping layer (20) has an extension (21) extending over the grooved region (121), and the second doping layer (30) has a wrapping portion (31) that covers and re-bonds the first surface (211) of the extension (21). In this case, on the one hand, due to the presence of the groove region (121), the extension (21), and the wrapping region (31), the wrapping region (31) reconnects with the first surface (211) of the extension (21), and one side of the two reconnection regions becomes the groove region (121) without any part of the silicon wafer (i.e., there is a slot on one side of the reconnection location), and the edge reconnection caused by the boundary region between the two affects only the silicon wafer (10) on one side of the groove region (121) (shaded area A in FIG. 4), and the range of influence is narrow, thereby narrowing the range of the silicon wafer (10) radiated by the boundary region, effectively reducing the number of carriers affected in the silicon wafer (10), and increasing the filling rate, thereby improving the electrical performance and efficiency of the back contact solar cell (100); on the other hand, at a predetermined location (123), the reconnection between the wrapping region (31) and the first surface (21) of the extension provides a specific reconnection region for electrical injection During this time, the current can be increased, and the repair efficiency and effect can be improved during subsequent repair of the rear contact solar cell (100).

[0036] In this embodiment, the side (213) of the extension (21) may or may not be covered by the wrapping portion (31), and preferably, the side (213) of the extension (21) is not covered by the wrapping portion (31) (as shown in FIG. 4). Meanwhile, the side (213) of the extension (21) that is not covered by the wrapping portion (31) can prevent the excessively large recombination area between the extension (21) and the wrapping portion (31) from affecting the battery efficiency.

[0037] FIG. 5 presents a design scheme for the light-shielding surface of a rear-contact solar cell in the prior art. In the prior art method, a P-type doping layer (2) and an N-type doping layer (1) on the light-shielding surface of the rear-contact solar cell are placed flat on the light-shielding surface of a silicon wafer. Edge recombination occurs at the junction of the P-type doping layer (2) and the N-type doping layer (1), affecting the number of carriers, and the range of influence is shown in shaded area B of FIG. 5. Edge recombination affecting a wide range reduces cell efficiency.

[0038] However, in the present application, the second doping layer (30) disposed within the groove region (121) has an extension (21) extending over the groove region (121), and the second doping layer (30) has a wrapping portion (31) that reconnects with the first surface (211) of the extension (21) only at a predetermined position (123) and at the junction of the wrapping portion (31) and the extension (21). The groove region (121) has a silicon wafer (10) on only one side. Their edge reconnection affects only the silicon wafer (10) on one side of the groove region (121), the range of influence is narrow, and the efficiency of the back contact solar cell (100) can be effectively improved.

[0039] In the embodiments of the present application, it should be noted that the “predetermined location (123) of the groove area (121)” may be understood as the entire groove area (121) or a part of the groove area (121), and that this is not limited in the present application. If the predetermined location (123) refers to the entire groove area (121), the predetermined location (123) is present only in a single groove area (121) or a part of the groove area (121) of the entire shading surface (12).

[0040] In an embodiment of the present invention, a predetermined location (123) is preferably a part of a groove area (121). In this case, a single or multiple predetermined locations (123) may be set in each groove area (121), and multiple predetermined locations (123) may be spaced apart along the longitudinal direction, which is not limited herein. As illustrated in FIG. 3, for example, two predetermined locations (123) are provided in a single groove area (121). Of course, a single or more predetermined locations (123) may be provided in a single groove area (121), which is not limited herein.

[0041] Additionally, in embodiments of the present application, a predetermined location (123) may be provided in a single or multiple groove area (121), and this is not limited in the specification. As illustrated in FIG. 3, for example, a groove area (121) having a predetermined location (123) is a groove area (121) located on both edges in the transverse direction of the rear contact solar cell (100). Of course, in other embodiments, a predetermined location (123) may be provided in a single or multiple groove area (121), and the groove area (121) may also be located in the middle or at other locations of the rear contact solar cell (100), and this is not limited in the specification.

[0042] Additionally, it should be noted that in the present application, "the wrapping portion (31) reconnects with the extension portion (21) toward the first surface (211)" means that there is no insulation between the two, and they can be reconnected through direct contact or through tunneling through another dielectric layer. For example, the two can be reconnected through the second dielectric layer (80) mentioned below.

[0043] In some embodiments, a plurality of predetermined locations (123) may be uniformly distributed on the light-shielding surface (12) of the silicon wafer (10). For example, as shown in FIG. 3, four predetermined locations (123) may be distributed at four corners of the back contact solar cell (100). By placing a plurality of points on the light-shielding surface (12) where the second doping layer (30) contacts the first doping layer (20), the current during electrical injection can be increased and the subsequent repair effect of the back contact solar cell (100) can be further enhanced.

[0044] In the present application, the silicon wafer (10) may be a P-type silicon wafer or an N-type silicon wafer, preferably an N-type silicon wafer, and is not limited thereto.

[0045] In a possible embodiment, in the manufacturing process, a silicon wafer (10) may first be cleaned, and then a first doping layer (20) may be manufactured over the entire light-shielding surface (12) of the silicon wafer (10). After that, a portion of the first doping layer (20) may be removed by etching or other methods, and a plurality of slots may be formed on the light-shielding surface (12) of the silicon wafer (10) to form a non-groove area (122) and a groove area (121), and at a predetermined position (123), the first doping layer (20) has an extension portion (21) that extends over the groove area (121). In a possible embodiment, for example, a portion of the groove area may be formed by laser or etching, and then the slot area may be horizontally expanded by etching so that the extension portion (21) extends over the groove area.

[0046] Next, a second doping layer (30) can be manufactured in the home area (121), and at a predetermined location (123), the second doping layer (30) has a wrapping portion (31) that extends along the sidewall surface of the home area (121) and covers the first surface (211) of the extension portion (21).

[0047] As illustrated in FIG. 4, the side (213) of the extension (21) can be understood as a surface connecting the first surface (211) and the second surface (212) in the extension (21), that is, a cross-section of one end of the extension (21).

[0048] In an embodiment of the present invention, the back contact solar cell (100) further comprises a first electrode (40) and a second electrode (50). The first electrode (40) may be placed in a non-grooved region (122) to maintain ohmic contact with the first doping layer (20), and the second electrode (50) may be placed in a grooved region (121) to maintain ohmic contact with the second doping layer (30). The first electrode (40) may be an N-type electrode, the second electrode (50) may be a P-type electrode, or vice versa, and the second electrode (50) may be an N-type electrode. The polarity of the first electrode (40) and the second electrode (50) corresponds to the polarity of the first doping layer (20) and the second doping layer (30), respectively, and both are metal electrodes.

[0049] Additionally, referring to FIG. 6, in the back contact solar cell (100) presented in the applied embodiment, a passivation film layer (60) covering the entire light-shielding surface (12) may be provided on the light-shielding surface (12) of the silicon chip (10). A first electrode (40) located in a non-groove region (122) penetrates the passivation film layer (60) to form an ohmic contact with a first doping layer (20), and a second electrode (50) located in a groove region (121) penetrates the passivation film layer (60) to form an ohmic contact with a second doping layer (30).

[0050] Additionally, in an embodiment of the present invention, it can be seen that physical separation is provided between the first doping layer (20) and the second doping layer (30) in the home region (121), except for a predetermined location (123), that is, in the region excluding the predetermined location (123), the first doping layer (20) does not have an extension (21) and the second doping layer (30) does not have a wrapping (31).

[0051] In this way, physical separation between the first doping layer (20) and the second doping layer (30), excluding the area corresponding to the predetermined location (123), can avoid the effect on the efficiency of the back contact solar cell (100) due to excessive contact area.

[0052] Specifically, in this embodiment, physical separation between the first doping layer (20) and the second doping layer (30) is implemented directly through the groove region (121) or by other means such as an insulating part, except for a predetermined location (123), and this is not limited in this specification.

[0053] Referring to FIG. 7, additionally, in some embodiments, the back contact solar cell (100) may include a first dielectric layer (70) stacked in a non-grooved region (122). A first doping layer (20) is stacked on the first dielectric layer (70) having a tunneling function, that is, the first dielectric layer (70), which may be a tunneling layer, is disposed between the region of the first doping layer (20) excluding the extension (21) and the silicon wafer (10). A film layer having passivation and tunneling functions, such as a silicon oxide tunneling layer, may be selected according to actual conditions, and is not limited in the specification.

[0054] The arrangement of the first dielectric layer (70) can effectively passivate the non-grooved region (122) to ensure efficiency while implementing a tunneling function.

[0055] Referring to FIG. 7, in some embodiments, the back contact solar cell (100) may include a second dielectric layer (80) stacked on a first surface (211). A wrapping portion (31) covers the second dielectric layer (80) to which the wrapping portion (31) reconnects with the first surface (211).

[0056] By arranging a second dielectric layer (80) between the wrapping portion (31) and the first surface (211), the passivation function of the first surface (211) is achieved, and at the same time, recombination between the wrapping portion (31) and the first surface (211) is enabled, thereby increasing the current during electrical injection and improving repair efficiency and effectiveness. In other words, by arranging the second dielectric layer (80), the passivation effect of the extension portion (21) can be ensured, while simultaneously improving repair efficiency and effectiveness.

[0057] Specifically, the second dielectric layer (80) may be an oxide layer such as a silicon oxide film or other film layer, and the specific type may be selected based on actual conditions and is not limited in this specification.

[0058] In addition, in some embodiments, the second dielectric layer (80) may have a thickness of 0.5 nm to 50 nm.

[0059] A second dielectric layer (80) having a thickness within a reasonable range of 0.5 nm to 50 nm can improve the electric injection of the battery while ensuring the passivation effect of the first surface (211), and can prevent poor passivation caused by a thin second dielectric layer (80) and low tunneling efficiency caused by a thick second dielectric layer (80).

[0060] Specifically, in this embodiment, the thickness of the second dielectric layer (80) may be, for example, 0.5 nm, 1 nm, 1.5 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 4.5 nm, 5 nm, 5.5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, or any value between 0.5 nm and 50 nm, and is not limited in this specification.

[0061] Referring to FIG. 8, in some embodiments, the first surface (211) has adjacent and continuous first region (213) and second region (214) along the arrangement direction of the groove region (121) and non-groove region (122). A second dielectric layer (80) is laminated on the first surface (211) of the extension (21), and the thickness of the second dielectric layer (80) in the second region (214) is thicker than the thickness of the second dielectric layer (80) in the first region (213). The portion of the second dielectric layer (80) located in the first region (213) has a tunneling function.

[0062] Specifically, the second dielectric layer (80) may be a film layer having a passivation function, such as an oxide layer, for example, a silicon oxide film layer, which has a tunneling function in the first region (213). The specific type may be selected based on actual conditions and is not limited in this specification.

[0063] The second dielectric layer (80) located in the first region (213) has a tunneling function, and since the thickness of the second dielectric layer (80) in the second region (214) is thicker than the thickness of the second dielectric layer (80) in the first region (213), the wrapping portion (31) can be re-coupled with the extension portion (21) of the first region (213) to increase the current during electrical injection, thereby improving subsequent repair efficiency and effect. Meanwhile, the thinner the second dielectric layer (80) in the first region (213), the better the electrical injection effect can be obtained, and the thicker the second dielectric layer (80) in the second region (214), the better the passivation effect can be improved. In other words, the thicker the second dielectric layer (80) of the second region (214) is than the second dielectric layer (80) of the first region (213), the better the electrical injection effect can be obtained, and the passivation effect can also be secured while improving repair efficiency and effect.

[0064] In a possible embodiment, during the manufacturing process, the silicon wafer (10) may be cleaned and fluffed, and the first dielectric layer (70) may be deposited over the entire light-shielding surface (12) of the silicon wafer (10), and then the first doping layer (20) may be formed on the first dielectric layer (70). A portion of the first doping layer (20) and the first dielectric layer (70) may be removed through etching and other means, and a plurality of slots are formed in the light-shielding surface (12) of the silicon wafer (10) so that a plurality of grooved regions (121) and non-grooved regions (122) are alternately arranged, and at a predetermined position (123), an extension (21) of the first doping layer (20) extends over the grooved region (121). In a possible embodiment, for example, some slots are formed by laser or etching, and then the slot area is horizontally extended by etching so that the first doping layer (20) has an extension (21) that extends over the groove area (121).

[0065] Next, a second dielectric layer (80) can be deposited on the first surface (211) of the extension (21). In some possible embodiments, the thickness of the second dielectric layer (80) in the first region (213) of the first surface (211) can be reduced to be smaller than the thickness of the second dielectric layer (80) in the second region (214) of the first surface (211) by two depositions.

[0066] Then, a second doping layer (30) can be deposited by deposition in the home region (121), and at a predetermined location (123), the second doping layer (30) has a lapping portion (31) stacked to cover the second dielectric layer (80).

[0067] Referring to FIG. 9, in some embodiments, at a predetermined location (123) of the groove region (121), the wrapping portion (31) may wrap around the first surface (211), end and second surface (212) of the entire extension (21), that is, the wrapping portion (31) may extend along the side of the groove region (121) to cover the second dielectric layer (80), wrap around the end of the extension (21), and cover the second surface (212) of the extension (21), and even the first doping layer (20) on the non-groove region (122). In this case, an insulating layer (120) (as shown in FIG. 9) may be provided between the wrapping portion (31) and the second surface (212), which may be a dielectric layer having an insulating function, such as a silicon oxide layer, a silicon nitride layer, etc.

[0068] As illustrated in FIGS. 4 to 8, in some embodiments, of course, the wrapping portion (31) may cover only the first surface (211) of the extension portion (21). Also, in other embodiments, the wrapping portion (31) may cover only the first surface (211) and the end of the extension portion (21) (i.e., the end surface of the extended end of the extension portion (21) in FIGS. 4 to 8), and this is not limited in the specification.

[0069] In some embodiments, the second dielectric layer (80) may have a thickness of 0.5 nm to 6 nm in the first region (213) and a thickness of 2 nm to 50 nm in the second region (214).

[0070] A second dielectric layer (80) having a thickness within a reasonable range of 0.5 nm to 6 nm in the first region (213) can improve the electric injection of the battery while ensuring the passivation effect of the first surface (211), and can prevent passivation failure due to a thin first region (213) and low tunneling efficiency due to a thick first region (213). A second dielectric layer (80) having a thickness within a reasonable range of 2 nm to 50 nm in the second region (214) can prevent passivation failure due to a thin second region (214) and low tunneling efficiency due to a thick second region (214).

[0071] Specifically, in this embodiment, the thickness of the second dielectric layer (80) in the first region may be, for example, 0.5 nm, 1 nm, 1.5 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 4.5 nm, 5 nm, 5.5 nm, 6 nm, or any value between 0.5 nm and 6 nm, and is not limited in the specification. The thickness of the second dielectric layer (80) in the second region (214) may be, for example, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, or any value between 2 nm and 50 nm, and is not limited in the specification.

[0072] In addition, in this embodiment, it is preferable that the second dielectric layer (80) has a thickness of 4 nm to 5 nm in the first region (213) and a thickness of 15 nm to 45 nm in the second region (214).

[0073] Specifically, the inventor of the present application has discovered through verification and research that if the thickness of the first region (213) is less than 4 nm or greater than 5 nm, it is more likely to lead to a reduction in passivation effect or a decrease in tunneling efficiency. On the other hand, if the thickness of the second region (214) is less than 15 nm or greater than 45 nm, it may lead to a reduction in passivation effect or a significant increase in cost. Research and verification show that a second dielectric layer (80) having a thickness within a preferred range of 4 nm to 5 nm in the first region (213) can increase tunneling efficiency and improve subsequent repair efficiency while ensuring the passivation effect of the first region (213). Meanwhile, a second dielectric layer (80) having a thickness within a preferred range of 15 nm to 45 nm in the second region (214) can effectively control costs while ensuring the passivation effect of the second region (214).

[0074] In these embodiments, the thickness of the second dielectric layer (80) in the first region (213) may preferably be 4 nm, 4.1 nm, 4.2 nm, 4.3 nm, 4.4 nm, 4.5 nm, 4.6 nm, 4.7 nm, 4.8 nm, 4.9 nm, 5 nm, or any value between 4 nm and 5 nm, and is not limited in the specification. The thickness of the second dielectric layer (80) in the second region (214) may preferably be 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, or any value between 15 nm and 45 nm, and is not limited in the specification.

[0075] In some embodiments, along the arrangement direction of the groove region (121) and the non-groove region (122) (i.e., the transverse direction in FIG. 3), the length of the first region (213) may be 0.05 µm to 1 µm, and the length of the second region (214) may be 0.1 µm to 10 µm.

[0076] The first region (213) and the second region (214), having lengths within the aforementioned reasonable range, effectively ensure that the re-coupling area of ​​the wrapping portion (31) and the extension portion (21) falls within a reasonable range, thereby increasing the current during electrical injection and ensuring repair efficiency and effectiveness. Additionally, this arrangement can prevent the first region (213) and the second region (214) from being too short, which would result in a re-coupling area that is too small and thus fail to achieve the desired repair effect. Furthermore, it can prevent the re-coupling area between the first region (213) and the second region (214) from being too long, which would have an excessively large re-coupling area that affects the efficiency of the rear contact solar cell (100).

[0077] Specifically, in this embodiment, the length of the first region (213) may be 0.05um, 0.1um, 0.1um, 0.2um, 0.25um, 0.3um, 0.35um, 0.4um, 0.45um, 0.5um, 0.55um, 0.6um, 0.65um, 0.7um, 0.75um, 0.8um, 0.85um, 0.9um, 0.95um, 1um, or any value between 0.05um and 1um, and is not limited in this specification. The length of the second region (214) may be, for example, 0.1 µm, 0.5 µm, 0.6 µm, 0.7 µm, 0.8 µm, 0.9 µm, 1 µm, 2 µm, 3 µm, 4 µm, 5 µm, 6 µm, 7 µm, 8 µm, 9 µm, 10 µm, or any value between 0.1 µm and 10 µm.

[0078] Additionally, in this embodiment, along the arrangement direction of the groove region (121) and the non-groove region (122), the length of the first region (213) may preferably be 0.5 µm to 1 µm, and the length of the second region (214) may preferably be 0.5 µm to 3 µm.

[0079] The first region (213) and the second region (214), having lengths within the above-mentioned desirable range, can ensure efficiency while maximizing the current during electric injection to improve repair efficiency and effectiveness, and also balance the battery efficiency and electric injection.

[0080] Specifically, the inventor of the present application has discovered through verification and research that a first region (213) with a length of less than 0.5 µm results in poor repair efficiency, and a first region (213) with a length greater than 1 µm results in reduced efficiency. The research and verification show that a first region (213) with a length within a desirable range of 0.5 µm to 1 µm can ensure stable efficiency while ensuring subsequent repair efficiency and effectiveness. Regarding the length of the second region (214), the inventor of the present application has discovered through verification and research that a second region (214) with a length of less than 0.5 µm is more likely to result in poor passivation effects of the extension (21), and a second region (214) with a length that is too long (greater than 3 µm) results in the extension (21) becoming too long, which significantly increases process difficulty and cost. Therefore, a second region (214) with a length within a desirable range of 0.5 µm to 3 µm can effectively control costs while ensuring passivation effects.

[0081] Referring to FIG. 9, in some embodiments, the first surface (211) and the second surface (212) intersect at the end of the extension (21) to form a tip portion (32) that is wrapped by the wrapping portion (31).

[0082] The end of the extension part (21) is pointed, and the wrapping part (31) surrounding the tip part (32) maintains only line surface contact with the tip of the tip part (32), so the contact area between the end of the extension part (21) and the wrapping part (31) is reduced, and consequently, recombination is reduced.

[0083] Of course, in some embodiments, the end of the extension (21) may not form a tip, that is, the first surface (211) and the second surface (212) may be connected through the end surface (see FIG. 4). In this case, the wrapping portion (31) may or may not wrap the end surface of the extension (21) (see FIG. 4), and this is not limited herein. If the wrapping portion (31) wraps the end surface of the extension (21), a dielectric layer may or may not be provided between the end surface and the wrapping portion (31). If provided, the dielectric layer may be a metal oxide layer, an intrinsic silicon layer, and other film layers, and this is not limited herein.

[0084] In addition, in some embodiments, a hole may be formed at the end of the tip portion (32).

[0085] The formation of a hole at the end of the tip portion (32) reduces the contact area between the wrapping portion (31) and the end of the tip portion (32), thereby reducing recombination.

[0086] In some embodiments, the extension (21) has a length of 0.15 µm to 10 µm in the arrangement direction (i.e., transverse direction) of the groove region (121) and non-groove region (122).

[0087] An extension (21) having a protrusion length within the aforementioned reasonable range can effectively ensure a reconnection area between the wrapping portion (31) and the extension (21) at a predetermined position (123), increase the current during electrical injection, and ensure repair efficiency and effectiveness. Additionally, the arrangement can prevent the extension (21) from being too short, which would result in a reconnection area that is too small and thus fail to achieve the desired repair effect, and it can also prevent the extension (21) from being too long, which would result in a reconnection area between the two parts becoming too large and thus affecting the efficiency of the rear contact solar cell (100).

[0088] Specifically, the length of the extension (21) may be, for example, 0.15 µm, 0.2 µm, 0.4 µm, 0.6 µm, 0.8 µm, 1 µm, 2 µm, 3 µm, 4 µm, 5 µm, 6 µm, 7 µm, 8 µm, 9 µm, 10 µm, or any value between 0.15 µm and 10 µm, and is not limited in this specification.

[0089] In some embodiments, in the longitudinal direction of the home region (121) (i.e., the longitudinal direction in FIG. 3), the ratio of the sum of the lengths of all extensions (21) on the light-shielding surface (12) of the silicon wafer (10) to the area of ​​the light-shielding surface (12) is 0.003 cm / cm 2 ~0.6cm / cm 2 am.

[0090] By rationally controlling the ratio of the total length of all extensions (21) in the longitudinal direction of the home area (121) to the area of ​​the light-shielding surface (12) of the silicon wafer (10), it is possible to prevent the total length of the extensions (21) in the longitudinal direction of the home area (121) from being too short to obtain the necessary repair effect, and also to prevent the ratio of the extensions (21) from being too large to affect the cell efficiency, that is, both the efficiency and repair effect of the rear contact solar cell (100) can be secured.

[0091] Specifically, in the present application, as illustrated in FIG. 3, the longitudinal direction of the groove region (121) is the extension direction of the groove region (121), that is, the longitudinal direction of the back contact type solar cell (100). The length of the extension (21) in the longitudinal direction of the groove region (121) is the width of the extension (21) along the longitudinal direction of the back contact type solar cell (100), that is, the ratio of the sum of the longitudinal widths of all extensions (21) on the entire cell to the area of ​​the light-shielding surface (12) of the silicon wafer (10) is 0.003 cm / cm 2 ~0.6cm / cm 2is. For example, FIG. 3 illustrates four extensions (21), and the ratio of the sum of the longitudinal widths of the four extensions (21) to the area of ​​the shading surface (12) is 0.003 cm / cm 2 ~0.6cm / cm 2 am.

[0092] In an embodiment of the present application, the ratio of the total length of all extensions (21) on the light-shielding surface (12) of the silicon wafer (10) to the area of ​​the light-shielding surface (12) of the silicon wafer (10) is, for example, 0.003 cm / cm 2 , 0.01cm / cm 2 , 0.02cm / cm 2 , 0.03cm / cm 2 , 0.04cm / cm 2 , 0.05cm / cm 2 , 0.06cm / cm 2 , 0.07cm / cm 2 , 0.08cm / cm 2 , 0.09cm / cm 2 , 0.1cm / cm 2 , 0.2cm / cm 2 , 0.3cm / cm 2 , 0.4cm / cm 2 , 0.5cm / cm 2 , 0.6cm / cm 2 , or 0.003cm / cm 2 ~0.6cm / cm 2 It may be any value between, and is not specifically limited in this specification.

[0093] In some embodiments, in a single groove area (121), the number of predetermined positions (123) is M, and the number of extensions (21) and wrapping portions (31) is also M (for example, as shown in FIG. 3, the number of predetermined positions (123) in a single groove area (121) is 2). In the longitudinal direction of the groove area (121), the ratio of the total length of the M extensions (21) to the length of the single groove area (121) is 0.005 to 0.5, and M is a positive integer greater than or equal to 1.

[0094] If the ratio of the total length of the extension (21) to the length of the home area (121) at all predetermined positions (123) in the longitudinal direction of the home area (121) is set within a reasonable range, it is possible to prevent the ratio of the extension (21) in a single home area (121) from being too small to obtain the necessary repair effect, and to avoid the ratio of the extension (21) in a single home area (121) from being too large to affect the cell efficiency, that is, both the efficiency and repair effect of the rear contact solar cell (100) can be guaranteed.

[0095] Specifically, as illustrated in FIG. 3, in this embodiment, the "sum of the lengths of M extensions (21) in the longitudinal direction of the groove area (121)" can be understood as the sum of the widths of all extensions (21) in the longitudinal direction of the rear contact solar cell (100). The length of the groove area (121) is the length of the extension of the groove area (121) in the longitudinal direction of the rear contact solar cell (100). In some embodiments, for example, the length of a single extension (21) in the longitudinal direction may be 0.1 cm, the total length of the groove area (121) is 10 cm, and M is 5. The total length of all extensions (21) is 0.5 cm and occupies 0.05 of the total length of the groove area (121).

[0096] In this embodiment, the ratio of the total length of the M extensions (21) to the length of the groove area (121) may be 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, or any value between 0.005 and 0.5, and is not limited in this specification.

[0097] In some embodiments, in the light-shielding surface (12) of the silicon wafer (10), the ratio of the sum of the orthographic projection areas (i.e., orthographic projection areas along the thickness direction) of all extensions (21) in the light-shielding surface (12) of the silicon wafer (10) to the area of ​​the light-shielding surface (12) of the silicon wafer (10) is 4.5 × 10 -8 ~1.5×10 -5 am.

[0098] If the ratio of the orthogonal projection area of ​​all extensions (21) is set within this reasonable range, it is possible to prevent the repair effect from being reduced because the area ratio of the extensions (21) is too small, and it is possible to prevent the efficiency of the rear contact solar cell (100) from being seriously affected because the area ratio of the extensions (21) is too large, that is, it is possible to ensure both the efficiency and the repair effect of the rear contact solar cell (100).

[0099] Specifically, in this embodiment, the ratio of the total orthogonal projection area of ​​all extensions (21) on the light-shielding surface (12) of the silicon wafer (10) to the light-shielding surface (12) of the silicon wafer (10) is 4.5 × 10 -8 , 5×10 -8 , 6×10 -8 , 7×10 -8 , 8×10 -8 , 9×10 -8 , 1×10 -7 , 1×10 -6 , 1×10 -5 , 1.5×10 -5 , or 4.5×10 -8 ~1.5×10 -5 It may be any other value between them, and is not limited to this specification.

[0100] Referring to FIGS. 7 through 9, in some embodiments, a third dielectric layer (90), which may be an oxide tunneling layer, may be provided between the bottom and side surfaces of the groove region (121) and the second doping layer (30). In some embodiments, for example, the third dielectric layer (90) may be a silicon oxide tunneling layer, and the presence of the third dielectric layer (90) may provide ideal passivation to the groove region (121). The thickness of the third dielectric layer (90) may be determined according to actual conditions and is not limited herein.

[0101] Referring to FIG. 10, in some embodiments, at a predetermined location (123), a third doping layer (110) is laminated on the second surface of the extension (21). The third doping layer (110) has the same polarity as the second doping layer (30) and covers the second surface (212), and an insulating layer (120) is provided between the second surface (212) of the extension (21) and the third doping layer (110) facing opposite directions in the groove region (121).

[0102] Specifically, in the process of manufacturing a rear contact solar cell (100), when a second doping layer (30) is deposited to form a wrapping portion (31), the wrapping portion (31) may be extended to cover a first surface (211), a side (213) of an extension portion (21), and a second surface (212) opposite to the first surface (211). To prevent re-coupling of the wrapping portion (31) at the side (213) of the extension portion, the wrapping portion (31) at the side (213) must be removed later. In this case, an insulating layer (120) is disposed on the surface of the extension portion (21) and the second surface (212) to prevent excessive re-coupling by separating the doping layer on the second surface (212) opposite the first surface (211) from the extension portion (21). Meanwhile, with the help of the insulating layer (120), the doping layer on the side (213) can be removed in a single process without removing the doping layer on the second surface (212) opposite the first surface (211), thereby reducing the difficulty and cost of the process. The doping layer maintained on the second surface (212) opposite the first surface (211) is the third doping layer (110).

[0103] In this embodiment, the insulating layer (120) may be a dielectric layer having an insulating function, such as a silicon oxide film, a silicon nitride film, etc.

[0104] Additionally, as illustrated in FIG. 10, in this embodiment, the third doping layer (110) may cover a portion of the first doping layer (20). In this case, the third doping layer (110) and the first doping layer (20) are also separated by an insulating layer (120). The first electrode (40) may be placed in an area of ​​the first doping layer (20) not covered by the third doping layer (110) to maintain ohmic contact with the first doping layer (20) and insulating separation with the third doping layer (110), while the second electrode (50) may be placed in a corresponding area of ​​the groove region (121) to maintain ohmic contact with the second doping layer (30).

[0105] In some embodiments, the depth of the groove area (121) (i.e., the depth of the depression, that is, the depth of the slot forming the groove area (121)) may be 0.1 µm to 15 µm.

[0106] A groove region (121) having a depth within such a reasonable range can prevent the affected area from extending from the bottom of the groove region (121) to the silicon wafer (10) due to a shallow groove region (121) when the wrapping portion (31) is re-coupled with the extension portion (21), and can also avoid a significant reduction in the strength of the silicon wafer (10) due to an excessive depth of the groove region (121). In other words, a groove region (121) having a depth within such a reasonable range can minimize the affected area while ensuring the strength of the silicon wafer (10) when the wrapping portion (31) is re-coupled with the extension portion (21).

[0107] Specifically, the inventor of the present application discovered that when the depth of the groove region (121) is less than 0.1 µm, the range of influence of the re-coupling between the wrapping portion (31) and the extension portion (21) is not limited to only one side of the groove region (121) but extends to the bottom of the groove region (121), thereby making the range of influence wider. A groove region (121) having a depth greater than 0.1 µm can prevent this problem and minimize the range of influence on the silicon wafer (10) as much as possible, but a groove region (121) having a depth greater than 15 µm will severely reduce the overall strength and increase the risk of cracking of the silicon wafer (10).

[0108] In this embodiment, the depth of the home region (121) may be, for example, 0.1 µm, 0.2 µm, 0.3 µm, 0.4 µm, 0.5 µm, 0.6 µm, 0.7 µm, 0.8 µm, 0.9 µm, 1 µm, 2 µm, 3 µm, 4 µm, 5 µm, 6 µm, 7 µm, 8 µm, 9 µm, 10 µm, 11 µm, 12 µm, 13 µm, 14 µm, 15 µm, or any value between 0.1 µm and 15 µm, and is not limited thereto.

[0109] Example 2

[0110] As illustrated in FIGS. 11 through 15, where the structural schematic of Example 2 is presented, it should be noted that identical or similar labels always indicate identical or similar components, or components having identical or similar functions. Example 2 has different labeling rules than Example 1.

[0111] Referring to FIGS. 11 and 12, the back contact solar cell (100) of the present embodiment may include a silicon wafer (10), a first doping layer (20), and a second doping layer (30).

[0112] As illustrated in FIGS. 11 and 12, the light-shielding surface of the silicon wafer (10) may include a plurality of alternately arranged non-grooved regions (11) (i.e., corresponding to the non-grooved region (122) of Example 1) and grooved regions (12) (i.e., corresponding to the grooved region (121) of Example 1). A slot (121) is formed in the grooved region (12), and a plurality of slots (121) spaced apart on the silicon wafer (10) form the non-grooved region (11) and the grooved region (12), and the corresponding region between two adjacent slots (121) is the non-grooved region (11), and the region corresponding to the slot (121) is the grooved region (12). The non-grooved region (11) and the grooved region (12) may be alternately arranged in the transverse direction of the back contact solar cell (100), and the slot (121) extends in the longitudinal direction.

[0113] As illustrated in FIG. 12, the first doping layer (20) may be placed over the non-grooved region (11), and at a predetermined position (122) of the slot (121), the second doping layer (30) may include a first portion (21) over the non-grooved region (11) and a second portion (22) extending over the slot (121) (i.e., an extension in the corresponding embodiment 1).

[0114] The second doping layer (30) may be positioned in the slot (121), and at a predetermined position (122) of the slot (121), the second doping layer (30) covers the bottom surface and side of the slot (121) and wraps the surface (221) of the second part (22) facing the slot (121) (i.e., the bottom surface of the second part (22) in the drawing, corresponding to the first surface of Example 1) and the side (222) of the second part (22). The second doping layer (30) re-attaches with the surface (221) of the second part (22) facing the slot (121).

[0115] In this embodiment, the slot (121) is formed in the groove region (12) of the light-shielding surface of the silicon wafer (10). At a predetermined location (122) of the slot (121), the first doping layer (20) comprises a first portion (21) in the non-groov region (11) and a second portion (22) extending over the slot (121). At a predetermined location (122), the second doping layer (30) covers the bottom surface and side of the slot (121) and surrounds the surface (221) facing the slot (121) and the side (222) of the second portion (22). The second doping layer (30) re-bonds with the surface (221) of the second portion (22) facing the slot (121).

[0116] Because a slot (121) exists, there is no silicon wafer portion on one side of the boundary region where the second doping layer (30) and the first doping layer (20) recombine. The edge recombination generated by the boundary region affects only the silicon wafer (10) on one side of the slot (121), and the range of influence is narrow. Therefore, the range of silicon wafers radiated by the boundary region is narrowed, effectively reducing the number of carriers affected by the silicon wafer (10) and increasing the filling rate, thereby improving the electrical performance and efficiency of the back contact solar cell (100). Additionally, at a predetermined position (122), the second doping layer (30) covers the surface (221) and the side (222) of the second portion (22) facing the slot (121) of the first doping layer (20). The second doping layer (30) recombines with the surface (221) of the second portion (22) facing the slot (121). The wide recombination area between the second doping layer (30) and the first doping layer (20) increases the current during electrical injection and improves the repair efficiency and effectiveness in subsequent repairs of the back contact solar cell (100).

[0117] In embodiments of the present application, "a predetermined location (122) of the slot (121)" may be understood as the entire slot (121) or a partial location of the slot (121), and this is not limited in the specification. In embodiments of the present application, a predetermined location (123) is preferably a partial location of the groove area (121). In this case, a single or multiple predetermined locations (123) may be set in each groove area (121), and this is not limited in the specification. Also, in embodiments of the present application, a single or multiple groove areas (121) having a predetermined location (122) may be provided, and this is not limited in the specification. As illustrated in FIG. 3, for example, a slot (121) having a predetermined location (123) is a groove area (121) located on both transverse edges of a rear contact solar cell (100). Of course, in other embodiments, a single or more slots (121) having a predetermined position (123) may be provided, and the slots (121) may be located in the middle or other positions of the rear contact solar cell (100), which are not limited in this specification.

[0118] Additionally, in this application, "reconnection contact between the surface (221) of the second portion (22) facing the slot (121) and the second doping layer (30)" means that there is no insulation between them and they can be reconnected through direct contact or another thin dielectric layer. For example, the two can be reconnected through the third thin dielectric layer (60) (oxide tunneling layer) described later.

[0119] In some embodiments, a plurality of predetermined locations (122) may be uniformly distributed on the light-shielding surface of the rear contact solar cell (100). For example, as shown in FIG. 11, four predetermined locations (122) may be distributed at the four corners of the rear contact solar cell (100). Introducing contact points between the second doping layer (30) and the first doping layer (20) on the light-shielding surface can increase the current during electrical injection and further enhance the subsequent repair effect of the rear contact solar cell (100).

[0120] In a possible embodiment, in the manufacturing process, a silicon wafer (10) is first cleaned, and then a first doping layer (20) may be formed over the entire light-shielding surface (12) of the silicon wafer (10). A slot (121) may be formed by etching or other means, thereby forming a non-grooved area (11) and a grooved area (12), and at a predetermined position (122), a second portion (22) of the first doping layer (20) extends over the slot (121). In a possible embodiment, for example, some slots may be formed by a laser or etching, and then the area of ​​the slot may be horizontally expanded by etching so that the second portion (22) extends over the slot (121).

[0121] Subsequently, a second doping layer (30) may be manufactured in the slot (121) to cover the bottom surface and side of the slot (121) at a predetermined location (122), and to wrap the surface (221) facing the slot (121) and the side (222) of the second part (22). The second doping layer (30) may re-bond with the surface (221) of the second part (22) facing the slot (121), which is not limited in the specification.

[0122] As illustrated in FIG. 12, it should be noted that the side of the second part (22) can be understood as the end surface of the second part (22) extending over the slot (121), that is, in some embodiments, the second doping layer (30) may only cover the end surface of the second part (22) extending over the slot (121). Of course, in some embodiments, the second doping layer (30) may also simultaneously cover all sides of the second part (22) (i.e., may connect all lower and upper surfaces of the second part (22)), and this is not limited in the specification.

[0123] In this embodiment, the back contact solar cell (100) may further include a first electrode (not shown in FIG. 11 to 15) which may be an N-type electrode and a second electrode (not shown in FIG. 11 to 15) which may be a P-type electrode, both of which are metal electrodes. A passivation film layer may also be provided on the light-shielding surface of the silicon chip (10). The first electrode, located in a non-groove region (11) and penetrating the passivation film layer, maintains ohmic contact with the first doping layer (20) and maintains insulating separation with the second doping layer (30); that is, the first electrode may be located in a position where the first doping layer (20) is not wrapped or covered by the second doping layer (30), and the second electrode may be located in a slot (121) and penetrate the passivation film layer to maintain ohmic contact with the second doping layer (30).

[0124] Referring to FIGS. 13 and 14, additionally, in some embodiments, the back contact solar cell (100) also includes a first thin-film dielectric layer (40) on a non-groove region (11). A first doping layer (20) is disposed on the first thin-film dielectric layer (40), that is, the first thin-film dielectric layer (40) is provided between the region of the first doping layer (20) (excluding the second portion (22)) and the silicon wafer (10). The first thin-film dielectric layer (40) may be a tunneling layer such as a silicon oxide tunneling layer, and is not particularly limited in this specification. The presence of the first thin-film dielectric layer (40) can ensure efficiency by having an ideal passivation effect on the non-groove region (11).

[0125] In some embodiments, a portion of the second portion (22) extending over the slot (121) (i.e., the portion above position (121) in FIG. 13) is 0.15 µm to 10 µm long.

[0126] The extension (21) having a protruding length within the aforementioned reasonable range can effectively ensure a contact area with the second doping layer (30) at a predetermined position (122), increase the current during electrical injection, and ensure repair efficiency and effectiveness. Additionally, this arrangement can prevent the second part (22) from being too short, which would result in a recombination area that is too small and thus fail to achieve the desired repair effect, and also prevent the length from being too long, which would result in a contact area that is too large and thus affect the efficiency of the rear contact solar cell (100).

[0127] Specifically, in this embodiment, the length of the portion of the second part (22) extending over the slot (121) can be understood as the length dimension of the second part (22) in the arrangement direction of the non-groove area (11) and the groove area (12) (i.e., transverse direction in FIG. 11). In this application, the length of the portion of the second part (22) extending over the slot (121) may be 0.15 µm, 0.2 µm, 0.4 µm, 0.6 µm, 0.8 µm, 1 µm, 2 µm, 3 µm, 4 µm, 5 µm, 6 µm, 7 µm, 8 µm, 9 µm, 10 µm, or any value between 0.15 µm and 10 µm, and is not limited thereto.

[0128] In some embodiments, in the longitudinal direction of the home region (121) (i.e., the longitudinal direction in FIG. 3), the ratio of the sum of the lengths of all extensions (21) on the light-shielding surface (12) of the silicon wafer (10) to the area of ​​the light-shielding surface (12) is 0.003 cm / cm 2 ~0.6cm / cm 2 am.

[0129] By reasonably controlling the ratio of the total length of all extensions (21) in the longitudinal direction of the home area (121) to the area of ​​the light-shielding surface (12) of the silicon wafer (10), it is possible to prevent the total length of the extensions (21) in the longitudinal direction of the home area (121) from being too short to obtain the necessary repair effect, and also to prevent the ratio of the extensions (21) from being too large to affect the cell efficiency, that is, it is possible to ensure both the efficiency and the repair effect of the rear contact solar cell (100).

[0130] Specifically, in the present application, as illustrated in FIG. 11, the longitudinal direction of the slot (121) is the extension direction of the slot (121), that is, the longitudinal direction of the back contact solar cell (100). The length of the second part (22) in the longitudinal direction of the slot (121) is the width of the second part (22) along the longitudinal direction of the back contact solar cell (100); in other words, the ratio of the sum of the longitudinal widths of all second parts (22) on the entire cell to the area of ​​the light-shielding surface (12) of the silicon wafer (10) is 0.003 cm / cm 2 ~0.6cm / cm 2 is. For example, FIG. 11 illustrates four second parts (22), and the ratio of the sum of the longitudinal widths of the four second parts (22) to the area of ​​the shading surface is 0.003 cm / cm 2 ~0.6cm / cm 2 am.

[0131] In an embodiment of the present application, for example, the ratio of the total length of all second parts (22) on the back contact solar cell (100) to the area of ​​the light-shielding surface of the silicon wafer (10) is 0.003 cm / cm 2 , 0.01cm / cm 2 , 0.02cm / cm 2 , 0.03cm / cm 2 , 0.04cm / cm 2 , 0.05cm / cm 2 , 0.06cm / cm 2 , 0.07cm / cm 2 , 0.08cm / cm 2 , 0.09cm / cm 2 , 0.1cm / cm 2 , 0.2cm / cm 2 , 0.3cm / cm 2 , 0.4cm / cm 2 , 0.5cm / cm 2 , 0.6cm / cm 2 , or 0.003cm / cm 2 ~0.6cm / cm 2 The values ​​may be any values ​​between the above and are not specifically limited in this specification.

[0132] In some embodiments, in a single slot (121), the number of predetermined positions (122) is M, and the number of second parts (22) is also M (for example, as shown in FIG. 11, the number of predetermined positions (122) in a single slot (121) is 2). In the longitudinal direction of the slot (121), the ratio of the total length of the M second parts (22) to the length of the slot (121) is 0.005 to 0.5, and M is a positive integer greater than or equal to 1.

[0133] If the ratio of the total length of the second part (22) to the length of the slot (121) is set within a reasonable range at all predetermined positions (122) in the longitudinal direction of the slot (121), it is possible to prevent the necessary repair effect from being obtained because the ratio of the second part (22) in a single slot (121) is too small, and also to avoid the cell efficiency being affected because the ratio of the second part (22) in a single slot (121) is too large, that is, both the efficiency and the repair effect of the rear contact solar cell (100) can be guaranteed.

[0134] Specifically, as illustrated in FIG. 11, in this embodiment, the “sum of the lengths of M second parts (22) in the longitudinal direction of the slot (121)” can be understood as the sum of the widths of all second parts (22) in the total direction of the back contact solar cell (100). The length of the slot (121) is the extended length of the slot (121) in the longitudinal direction of the back contact solar cell (100). In some embodiments, for example, the length of a single second part (22) in the longitudinal direction may be 0.1 cm, the total length of the slot (121) is 10 cm, and M is 5. The total length of all second parts (22) is 0.5 cm, which accounts for 0.05 of the total length of the slot (121).

[0135] In these embodiments, the ratio of the total length of the M second parts (22) to the length of the slot (121) is 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5 or any value between 0.005 and 0.5, and is not limited in the specification.

[0136] In some embodiments, in a back contact solar cell (100), the ratio of the sum of the orthogonal projection areas (i.e., orthogonal projection areas along the thickness direction) of all second portions (22) of the light-shielding surface (12) of the silicon wafer (10) to the area of ​​the light-shielding surface of the silicon wafer (10) is 4.5 × 10 -8 ~1.5×10 -5 am.

[0137] By setting the ratio of the orthogonal projection area of ​​all second parts (22) within this reasonable range, it is possible to prevent poor repair effects caused by the area ratio of the second parts (22) being too small, and to prevent serious effects on the efficiency of the rear contact solar cell (100) caused by the area ratio of the second parts (22) being too large, that is, it is possible to ensure both the efficiency and repair effects of the rear contact solar cell (100).

[0138] Specifically, in this embodiment, the ratio of the total orthogonal projection area of ​​all second parts (22) of the light-shielding surface of the silicon wafer (10) to the light-shielding surface of the silicon wafer (10) is 4.5 × 10 -8 , 5×10 -8 , 6×10 -8 , 7×10 -8 , 8×10 -8 , 9×10 -8 , 1×10 -7 , 1×10 -6 , 1×10 -5 , 1.5×10 -5 , or 4.5×10 -8 ~1.5×10 -5It may be any other value between them, and is not limited to this specification.

[0139] Referring to FIGS. 13 and 14, in some embodiments, a second thin-film dielectric layer (50), which may be an oxide tunneling layer, may be provided between the bottom and side surfaces of the slot (121) and the second doping layer (30). In some embodiments, for example, the second thin-film dielectric layer (50) may be a silicon oxide tunneling layer, and the presence of the second thin-film dielectric layer (50) may provide ideal passivation to the slot (121). The thickness of the second thin-film dielectric layer (50) may be determined according to actual conditions and is not limited herein.

[0140] Referring to FIGS. 13 and 14, in some embodiments, a third thin film dielectric layer (60) may be provided between the surface (221) of the second portion (22) facing the slot (121) and the second doping layer (30). The second doping layer (30) is re-bonded to the surface (221) of the second portion (22) facing the slot (121) through the third thin film dielectric layer (60).

[0141] In this way, the second doping layer (30) is recombined with the second part (22) through the third thin film dielectric layer (60), increasing the current during electrical injection and providing better repair efficiency and effect when repairing the back contact solar cell (100) later.

[0142] Specifically, the third thin film dielectric layer (60) may be an oxide tunneling layer, for example, a silicon oxide tunneling layer, but is not limited thereto. The thickness of the third thin film dielectric layer (60) may be determined according to actual conditions.

[0143] Referring to FIG. 15, in some embodiments, the second doping layer (30) surrounds the surface (221) facing the slot (121) and the side (222) of the second part (22). The second doping layer (30) extends to the surface (223) of the second part (22) away from the slot (121) (i.e., the upper surface (223) of the second part in FIG. 15), and an insulating layer (70) is provided between the second doping layer (30) and the second part (22) so that the second doping layer (30) can extend to the surface (223) of the second part (22) away from the slot (121).

[0144] The arrangement of the insulating layer (70) separates the upper surface of the second part (22) from the second doping layer (30), thereby preventing excessive contact between the second doping layer (30) and the first doping layer (20).

[0145] Specifically, in this embodiment, the insulating layer (70) may also be a silicon oxide layer. Specifically, insulating performance can be provided by adjusting the thickness of the silicon oxide layer. For example, when the first thin film dielectric layer (40), the second thin film dielectric layer (50), the third thin film dielectric layer (60), and the insulating layer (70) are all silicon oxide layers, the thickness of the silicon oxide layer can be reduced so that the first thin film dielectric layer (40), the second thin film dielectric layer (50), and the third thin film dielectric layer (60) have a tunneling function, and when manufacturing the insulating layer (70), the thickness of the silicon oxide layer can be increased to provide an insulating function.

[0146] In this embodiment, the first electrode may be placed in an area of ​​the first doping layer (20) that is not covered by the second doping layer (30) and maintains ohmic contact with the first doping layer (20) to achieve insulation separation from the second doping layer (30), whereas the second electrode may be placed in an area corresponding to the slot (121) to maintain ohmic contact with the second doping layer (30).

[0147] Referring to FIG. 14, in some embodiments, a gap (2221) is formed in at least a portion of the area between the second doping layer (30) and the side (222) of the second portion (22).

[0148] The gap (2221) between the side (222) of the second part (22) and the second doping layer (30) can reduce recombination by reducing the contact area between the second doping layer (30) and the side (222) of the second part (22). In other words, if sufficient contact exists between the second doping layer (30) and the bottom surface of the second part (22), an enhanced electric injection effect can be provided, and forming a gap (2221) between the side (222) of the second part (22) and the second doping layer (30) can effectively ensure efficiency.

[0149] Specifically, during the manufacturing process, a porous structure may be formed between the second doping layer (30) and the side (222) of the second part (22), so that a gap (2221) may be formed in at least a portion of the area between the second doping layer (30) and the side (222) of the second part (22).

[0150] In some embodiments, the first doping layer (20) may have a thickness of 10 nm to 600 nm, which ensures efficiency while preventing the contact area between the side (222) of the second part (22) and the second doping layer (30) from being too large due to the first doping layer (20) being too thick, thereby preventing the efficiency from being affected.

[0151] Specifically, the thickness of the first doping layer (20) may be 10 nm, 50 nm, 80 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, or any value between 10 nm and 600 µm, and is not limited in the present specification.

[0152] Likewise, in these embodiments, the second doping layer (30) may also have a thickness of 10 nm to 600 nm, which is not limited in the specification.

[0153] In some embodiments, the depth of the slot (121) may be 0.1 µm to 15 µm.

[0154] A slot (121) having a depth within such a reasonable range can prevent the influence area from extending from the bottom of the slot (121) to the silicon wafer (10) due to a shallow slot (121) when the second doping layer (30) recombines with the second part (22), and can also prevent the strength of the silicon wafer (10) from being significantly reduced due to an excessive depth of the groove area (121). In other words, a slot (121) having a depth within such a reasonable range can minimize the influence area while ensuring the strength of the silicon wafer (10) when the second doping layer (30) recombines with the second part (22).

[0155] Specifically, the inventor of the present application discovered that when the depth of the groove region (121) is less than 0.1 µm, the range of influence of the re-coupling between the wrapping portion (31) and the extension portion (21) is not limited to one side of the groove region (121) but extends to the bottom of the groove region (121), thereby making the range of influence wider. A slot (121) having a depth greater than 0.1 µm can prevent this problem and minimize the range of influence on the silicon wafer (10) as much as possible, but a slot (121) having a depth greater than 15 µm severely reduces the overall strength and increases the risk of cracking of the silicon wafer (10).

[0156] In this embodiment, the depth of the home area (121) may be, for example, 0.1 µm, 0.2 µm, 0.3 µm, 0.4 µm, 0.5 µm, 0.6 µm, 0.7 µm, 0.8 µm, 0.9 µm, 1 µm, 2 µm, 3 µm, 4 µm, 5 µm, 6 µm, 7 µm, 8 µm, 9 µm, 10 µm, 11 µm, 12 µm, 13 µm, 14 µm, 15 µm, or any value between 0.1 µm and 15 µm, and is not limited thereto.

[0157] In some embodiments, physical separation is provided between the first doping layer (20) and the second doping layer (30) in the home region (12), except for a predetermined location (12). In this case, physical separation between the first doping layer (20) and the second doping layer (30), except for a predetermined location (122), can prevent the efficiency of the back contact solar cell (100) from being affected by an excessive contact area.

[0158] Specifically, in this embodiment, physical separation between the first doping layer (20) and the second doping layer (30), excluding a predetermined location (122), is implemented directly through the slot (121) or by other means such as an insulating part, and is not limited thereto.

[0159] In the description of this specification, the reference terms “some embodiments,” “exemplary embodiments,” “examples,” “specific examples,” or “some examples” refer to specific features, structures, materials, or properties described in connection with an embodiment or example included in at least one embodiment or example of this application. A schematic representation of the above terms in the specification does not necessarily refer to the same embodiment or example. Furthermore, the described specific features, structures, materials, or properties may be combined in an appropriate manner in any one or more embodiments or examples.

[0160] Furthermore, the foregoing description is merely a preferred embodiment of the present application and is not intended to limit the application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present application are included within the scope of protection of the present application.

Claims

Claim 1 A silicon wafer having a light-receiving face and a shady face facing each other, wherein the shady face is provided with a plurality of groove areas and a plurality of non-groove areas spaced apart, and the non-groove areas and the groove areas are alternately arranged; a first doping layer having a first doping layer stacked on the non-groove area, wherein at a predetermined position of the groove area, the first doping layer has an extension extending over the groove area, and the extension has a first surface facing the groove area and a second surface moving away from the groove area; A back contact solar cell comprising a second doping layer, wherein the second doping layer is laminated within the groove region and has polarity opposite to that of the first doping layer, and at a predetermined position the second doping layer has a wrapping portion extending along the sidewall surface of the groove region and covering the first surface, and a re-bonding region is formed between the wrapping portion and the first surface, wherein the groove region includes an opening on the light-shielding surface above the second doping layer, and the opening is formed inside the silicon wafer and has a depth from the light-shielding surface toward the light-receiving surface. Claim 2 In claim 1, the rear contact solar cell further comprises a first dielectric layer stacked on the non-grooved region, and the first doping layer is stacked on the first dielectric layer, the rear contact solar cell. Claim 3 A rear contact solar cell according to claim 1, wherein the rear contact solar cell further comprises a second dielectric layer stacked on the first surface, the wrapping portion covers the second dielectric layer, and a recombination region is formed between the first surface and the wrapping portion through the second dielectric layer. Claim 4 In paragraph 3, the second dielectric layer has a thickness of 0.5 nm to 50 nm, a back contact solar cell. Claim 5 In paragraph 3, along the arrangement direction of the groove region and the non-groove region, the first surface has adjacent and continuous first region and second region; the thickness of the second dielectric layer in the second region is thicker than the thickness of the second dielectric layer in the first region, and the portion of the second dielectric layer located in the first region has a tunneling function, a back contact solar cell. Claim 6 A back-contact solar cell according to claim 5, wherein the second dielectric layer in the first region has a thickness of 0.5 nm to 6 nm, and the second dielectric layer in the second region has a thickness of 2 nm to 50 nm. Claim 7 A back-contact solar cell according to claim 6, wherein the second dielectric layer in the first region has a thickness of 4 nm to 5 nm, and the second dielectric layer in the second region has a thickness of 15 nm to 45 nm. Claim 8 A back contact solar cell according to claim 5, wherein, along the arrangement direction of the groove region and the non-groove region, the length of the first region is 0.05 µm to 1 µm and the length of the second region is 0.1 µm to 10 µm. Claim 9 A back contact solar cell according to claim 8, wherein, along the arrangement direction of the groove region and the non-groove region, the length of the first region is 0.05 µm to 1 µm and the length of the second region is 0.5 µm to 3 µm. Claim 10 A rear contact solar cell according to claim 1, wherein the first surface and the second surface intersect at the end of the extension to form a tip, and the wrapping portion surrounds the tip. Claim 11 A rear contact solar cell according to claim 10, wherein a hole is formed at the end of the tip. Claim 12 A rear contact solar cell according to claim 1, wherein the extension portion has a length of 0.15 µm to 10 µm along the arrangement direction of the groove region and the non-groove region. Claim 13 In claim 1, the ratio of the total length of all extensions to the area of ​​the shading surface in the longitudinal direction of the groove area is 0.003 cm / cm 2 Up to 0.6cm / cm 2 Phosphor, rear contact solar cell. Claim 14 A rear contact solar cell according to claim 1, wherein in a single groove area, the number of predetermined positions is M, the number of extensions is M, and the number of wrapping parts is M; and in the longitudinal direction of the groove area, the ratio of the total length of the M extensions to the length of the single groove area is 0.005 to 0.5, and M is a positive integer greater than or equal to 1. Claim 15 In claim 1, the ratio of the total orthographic projection areas of all extensions of the shading surface to the area of ​​the shading surface is 4.5 × 10 -8 Up to 1.5×10 -5 Phosphor, rear contact solar cell. Claim 16 A back contact solar cell according to claim 1, wherein, at the predetermined position, a third doping layer stacked on the upper layer of the second surface has the same polarity as the second doping layer, the third doping layer covers the second surface, and an insulating layer is provided between the third doping layer and the second surface. Claim 17 A rear contact solar cell according to claim 1, wherein the depth of the groove region is 0.1 µm to 15 µm. Claim 18 A silicon wafer having a light-receiving face and a shady face facing each other, wherein the shady face includes a plurality of alternately arranged non-groove regions and groove regions, and a slot is formed in the groove region; a first doping layer, wherein the first doping layer is located over the non-groove region, and at a predetermined position of the slot, the first doping layer includes a first portion located over the non-groove region and a second portion extending over the slot; A back contact solar cell comprising a second doping layer, wherein the second doping layer is disposed in the slot, and at a predetermined position, the second doping layer covers the bottom surface and side surface of the slot, surrounds the surface of the second portion facing the slot and the side surface of the second portion, and a re-bonding region is formed between the second doping layer and the surface of the second portion facing the slot, and the groove region includes an opening on the light-shielding surface above the second doping layer, wherein the opening is formed inside the silicon wafer and has a depth from the light-shielding surface toward the light-receiving surface. Claim 19 In claim 18, the back contact solar cell further comprises a first thin dielectric layer on the non-grooved region, and the first doping layer is disposed on the first thin dielectric layer, the back contact solar cell. Claim 20 In claim 18, the second portion extending over the slot is 0.15 µm to 10 µm in length, a rear contact solar cell. Claim 21 In paragraph 18, the ratio of the total length of all second parts on the back contact solar cell to the area of ​​the shading surface of the silicon wafer in the longitudinal direction of the slot is 0.003 cm / cm 2 Up to 0.6cm / cm 2 Phosphor, rear contact solar cell. Claim 22 A back contact solar cell according to claim 18, wherein in a single slot, the number of the predetermined positions is M, the number of the second parts is M, and in the longitudinal direction of the slot, the ratio of the total length of the M second parts to the length of the single slot is 0.005 to 0.5, and M is a positive integer greater than or equal to 1. Claim 23 In paragraph 18, in the back contact solar cell, the total orthographic projection areas of all second portions on the shading surface of the silicon wafer are 4.5 × 10 of the total area of ​​the shading surface of the silicon wafer. -8 Up to 1.5×10 -5 A rear contact solar cell occupying. Claim 24 A rear contact solar cell according to claim 18, wherein a second thin dielectric layer is provided between the second doping layer and the bottom and side surfaces of the slot. Claim 25 A back-contact solar cell according to claim 18, wherein a third thin dielectric layer is provided between the second doping layer and the surface of the second portion facing the slot, and a recombination region is formed between the surface of the second portion facing the slot and the second doping layer through the third thin dielectric layer. Claim 26 A back contact solar cell according to claim 18, wherein the second doping layer wraps around the surface of the second portion facing the slot and the side of the second portion, extends to the surface of the second portion away from the slot, and an insulating layer is provided between the portion of the second doping layer extending to the surface of the second portion away from the slot and the second portion. Claim 27 A back contact solar cell according to claim 18, wherein a gap is formed in at least a portion of the area between the second doping layer and the side of the second portion. Claim 28 In claim 18, the back contact solar cell, wherein the first doping layer has a thickness of 10 nm to 600 nm. Claim 29 A back contact solar cell according to claim 18, wherein the depth of the slot is 0.1 µm to 15 µm. Claim 30 A back contact solar cell according to claim 18, wherein physical isolation is provided between the first doping layer and the second doping layer in the home region, excluding the predetermined location. Claim 31 A rear contact solar cell assembly comprising a rear contact solar cell described in any one of claims 1 to 30. Claim 32 A photovoltaic power generation system comprising a rear contact solar cell assembly as described in paragraph 31.

Images