Solar cell

Abstract

A solar cell, comprising a silicon substrate, and an oxide layer, an N-doped layer, a first passivation layer and first electrodes, which are sequentially arranged on the side of a back surface of the silicon substrate, wherein a plurality of first recesses are provided in the first passivation layer, the first recesses penetrate through an upper surface and a lower surface of the first passivation layer, and the first electrodes fill the first recesses and are electrically connected to the N-doped layer; and a plurality of connecting recesses are provided in the N-doped layer, the connecting recesses correspond to the first recesses in terms of position, the first electrodes fill the connecting recesses and are connected to the N-doped layer, and the ratio of the depth of each connecting recess to the thickness of the N-doped layer is greater than 0 and less than or equal to 0.2.

Description

solar cells

[0001] Related applications

[0002] This application claims priority to Chinese patent application number 202322181159.5, filed on August 14, 2023, entitled “Solar Cell,” which is hereby incorporated by reference in its entirety. Technical Field

[0003] The present application relates to the field of photovoltaic technology, and in particular to a solar cell. Background Art

[0004] Currently, PERC (Passivated Emitter and Rea rC) cells dominate crystalline silicon solar cells, but TOPCon (Tunnel Oxide Passivating Contacts) cells are rapidly developing due to their superior power generation efficiency and low cost. Compared to PERC cells, TOPCON cells have superior passivation, primarily due to their back-side passivation contact structure consisting of a tunnel oxide layer and a doped polysilicon layer. This passivation effect can be weakened or even completely destroyed by the placement of a back-side electrode.

[0005] Summary of the Invention

[0006] Based on this, it is necessary to provide a solar cell.

[0007] The present application provides a solar cell, comprising a silicon substrate, and an oxide layer, an N-type doping layer, a first passivation layer, and a first electrode sequentially arranged on a back side of the silicon substrate;

[0008] A plurality of first grooves are formed on the first passivation layer, the first grooves passing through the upper and lower surfaces of the first passivation layer, the first electrodes fill the first grooves and are electrically connected to the N-type doped layer;

[0009] The N-type doped layer is provided with a plurality of connection grooves, the connection grooves corresponding to the positions of the first grooves, the first electrodes are filled into the connection grooves and connected to the N-type doped layer, and the ratio of the depth of the connection grooves to the thickness of the N-type doped layer is greater than 0 and less than or equal to 0.2.

[0010] In some embodiments, a ratio of the depth of the connecting groove to the thickness of the N-type doping layer is 0.02 to 0.18.

[0011] In some embodiments, a ratio of the depth of the connecting groove to the thickness of the N-type doping layer is 0.02 to 0.1.

[0012] In some embodiments, the area of ​​the first groove is 30% to 80% of the area of ​​the first electrode.

[0013] In some embodiments, the spacing distance between adjacent first grooves is 5 nm to 1000 nm.

[0014] In some embodiments, the thickness of the first passivation layer is 75 nm to 90 nm.

[0015] In some embodiments, the thickness of the N-type doping layer is 80 nm to 130 nm.

[0016] In some embodiments, the cross-section of the first slot is circular or elliptical.

[0017] In some embodiments, the cross-sectional diameter of the first groove is 5 nm to 5000 nm.

[0018] In some embodiments, a connection between the first electrode and the N-type doped layer has a plurality of connection protrusions.

[0019] In some embodiments, adjacent connecting protrusions are tangential or spaced apart.

[0020] In some embodiments, the diameter of the connecting protrusion is 10 nm to 500 nm.

[0021] In some embodiments, the first electrode is a silver electrode, and the connecting protrusions are silver crystal particles.

[0022] In some embodiments, a P-type doped layer and a second passivation layer are stacked in sequence on the front side of the silicon substrate in a direction away from the silicon substrate, and a second electrode is provided on the surface of the second passivation layer away from the P-type doped layer, and the second electrode passes through the second passivation layer and is connected to the P-type doped layer.

[0023] In some embodiments, the solar cell is a TOPCon cell, and the oxide layer is a tunneling oxide layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0025] FIG1 is a schematic structural diagram of a solar cell provided in a specific embodiment of the present application.

[0026] FIG2 is a partial enlarged view of area I in FIG1 .

[0027] Among them, 100 is a solar cell; 110 is a silicon substrate; 120 is an oxide layer; 130 is an N-type doping layer; 131 is a connection groove; 140 is a first passivation layer; 150 is a first electrode; 151 is a first groove; 152 is a connection protrusion; 160 is a P-type doping layer; 170 is a second passivation layer; 180 is a second electrode; 190 is an aluminum oxide layer. DETAILED DESCRIPTION

[0028] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0029] It should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0030] In the description of this application, unless otherwise expressly specified or limited, the terms "connected," "connect," "fixed," and "disposed" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components or interactions between two components. A person of ordinary skill in the art will be able to understand the meanings of the above terms in this application based on the specific circumstances.

[0031] In this application, the terms "optionally," "optional," and "optional" mean optional or dispensable, i.e., they refer to either option being selected from two parallel options: "with" or "without." If a technical solution contains multiple "optional" clauses, each "optional" clause is independent unless otherwise specified and there are no contradictions or constraints.

[0032] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0033] The terms "first," "second," and the like in this application are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor as implicitly indicating the importance or quantity of the technical features being referenced. Furthermore, the terms "first," "second," and the like serve only as non-exhaustive enumerations and should not constitute closed-ended limitations on quantity.

[0034] In the present application, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to an integer in the numerical interval, including the two endpoint integers of the numerical range, and each integer between the two endpoints, is equivalent to directly enumerating each integer. When multiple numerical ranges are provided to describe a feature or characteristic, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical range disclosed in this application should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows broadly including quantitative intervals such as percentage intervals, ratio intervals, and ratio intervals.

[0035] In related technologies, the process of preparing the back electrode of TOPCon cells is prone to adverse effects on the passivation contact structure. For example, the electrode penetrates the doped polysilicon layer or even the tunnel oxide layer during the preparation process, destroying the passivation contact structure formed by the doped polysilicon layer and the tunnel oxide layer, reducing the passivation effect, and thus affecting the photoelectric performance of the TOPCon cell.

[0036] 1 and 2 , an embodiment of the present application provides a solar cell 100 , including a silicon substrate 110 , and an oxide layer 120 , an N-type doping layer 130 , a first passivation layer 140 , and a first electrode 150 sequentially disposed on the back side of the silicon substrate 110 .

[0037] A plurality of first grooves 151 are formed on the first passivation layer 140 . The first grooves 151 penetrate the upper and lower surfaces of the first passivation layer 140 . The first electrodes 150 fill the first grooves 151 and are electrically connected to the N-type doped layer 130 .

[0038] The N-type doped layer 130 is provided with a plurality of connection grooves 131, and the connection grooves 131 correspond to the positions of the first grooves 151. The first electrode 150 is filled into the connection grooves 131 and connected to the N-type doped layer 130. The ratio of the depth of the connection grooves 131 to the thickness of the N-type doped layer 130 is greater than 0 and less than or equal to 0.2.

[0039] In the embodiment of the present application, the first electrode 150 is embedded in and penetrates the first passivation layer 140, thereby forming an electrical contact with the N-type doped layer 130. By controlling the depth of the first electrode 150 embedded in the N-type doped layer 130, that is, controlling the depth of the connecting groove 131, on the one hand, the first electrode 150 is in contact with the N-type doped layer 130 and thus electrically connected, and on the other hand, it avoids damaging the passivation effect of the oxide layer 120 and the N-type doped layer 130, thereby effectively improving the photoelectric conversion efficiency of the solar cell 100.

[0040] In the embodiment of the present application, the ratio of the depth of the connecting groove 131 to the thickness of the N-type doping layer 130 is controlled to be less than 0.2. If the depth of the connecting groove 131 is relatively large, the electrode slurry may corrode the N-type doping layer 130 over a large area, affecting the passivation effect formed by the N-type doping layer 130 and the oxide layer 120.

[0041] In some embodiments, the ratio of the depth of the connecting groove 131 to the thickness of the N-type doped layer 130 is 0.02-0.18, and can further be 0.02-0.1, for example, 0.02, 0.04, 0.06, 0.08, 0.10, 0.12, 0.14, 0.16, 0.18, 0.20 or any value therebetween.

[0042] It should be noted that the present application does not impose any specific requirements or restrictions on the thickness of each structural layer in the solar cell 100 . Those skilled in the art may reasonably select the thickness of each structural layer according to actual needs to meet different usage requirements.

[0043] In some embodiments, the silicon substrate 110 is an N-type doped silicon substrate.

[0044] In some embodiments, the silicon substrate 110 has a thickness of 110 μm to 150 μm, for example, 110 μm, 115 μm, 120 μm, 125 μm, 130 μm, 135 μm, 140 μm, 145 μm, or 150 μm.

[0045] In some embodiments, the oxide layer 120 may be a silicon dioxide layer. Optionally, the oxide layer 120 has a thickness of 1.5 nm to 5 nm, for example, 1.5 nm, 2.0 nm, 2.5 nm, 3.0 nm, 3.5 nm, 4.0 nm, 4.5 nm, or 5.0 nm.

[0046] In some embodiments, the first electrode 150 may be a silver electrode.

[0047] In some embodiments, the area of ​​the first groove 151 is 30% to 80% of the area of ​​the first electrode 150, for example, it can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80% or any value therebetween.

[0048] The present application controls the area of ​​the first groove 151 to ensure good bonding stability between the first electrode 150 and the first passivation layer 140, effectively ensuring that the back first electrode 150 can be embedded in the first passivation layer 140 and maintain stable contact with the N-type doped layer 130. If the area of ​​the first groove 151 is relatively small, the bonding between the first electrode 150 and the first passivation layer 140 may be unstable, resulting in detachment. If the area of ​​the first groove 151 is relatively large, it may cause severe corrosion of the N-type doped layer 130, affecting the passivation effect of the N-type doped layer 130 and the oxide layer 120, and further affecting the photoelectric conversion efficiency of the solar cell 100.

[0049] It should be noted that, in this application, the area of ​​the first groove 151 refers to the opening area of ​​the first groove 151 on the surface of the first passivation layer 140 near the first electrode 150. The area of ​​the first electrode 150 refers to the area of ​​the surface of the first passivation layer 140 near the first electrode 150 covered by the first electrode 150. More specifically, the total area of ​​all first grooves 150 corresponding to the same first electrode 150 is 30% to 80% of the area of ​​the first electrode 150, and / or the total area of ​​all first grooves 150 in the first passivation layer 140 is 30% to 80% of the total area of ​​all first electrodes 150.

[0050] In the embodiment of the present application, the first electrode 150 is connected to the N-type doped layer 130 through the first groove 151, which not only improves the bonding stability between the first electrode 150 and the first passivation layer 140, but also reduces the corrosion of the electrode slurry on the N-type doped layer 130 during the preparation of the solar cell and improves the electrical connection effect between the first electrode 150 and the N-type doped layer 130.

[0051] It should be noted that the present application does not impose any specific requirements or restrictions on the shape of the first slot 151. Optionally, the first slot 151 may be conical or cylindrical, for example, conical or cylindrical terraced.

[0052] The plurality of first grooves 151 are spaced apart from each other. In some embodiments, the spacing between adjacent first grooves 151 is 5 nm to 1000 nm, for example, 5 nm, 10 nm, 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, or any value therebetween.

[0053] In the embodiment of the present application, the spacing distance between the first grooves 151 is controlled to prevent the first grooves 151 from being connected to each other into sheets. If the spacing distance between the first grooves 151 is small, not only will the bonding stability of the back electrode 150 be poor, but it will also easily cause the N-type doped layer 130 to be corroded over a large area by the electrode slurry during the preparation of the solar cell, thereby affecting the passivation effect between the N-type doped layer 130 and the oxide layer 120.

[0054] In some embodiments, the thickness of the first passivation layer 140 is 75 nm to 90 nm, for example, 75 nm, 76 nm, 78 nm, 80 nm, 82 nm, 84 nm, 86 nm, 88 nm or 90 nm. Optionally, the first passivation layer 140 may be a silicon nitride (SiNx) layer.

[0055] In some embodiments, the N-type doped layer 130 may be an N-type doped polysilicon layer.

[0056] In some embodiments, the thickness of the N-type doped layer 130 is 80 nm to 130 nm, for example, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, 105 nm, 110 nm, 115 nm, 120 nm, 125 nm, or 130 nm.

[0057] In some embodiments, the cross-section of the first slot 151 is circular or elliptical.

[0058] In some embodiments, the cross-sectional diameter of the first groove 151 is 5 nm to 5000 nm, for example, 5 nm, 50 nm, 500 nm, 1000 nm, 1500 nm, 2000 nm, 2500 nm, 3000 nm, 3500 nm, 4000 nm, 4500 nm, or 5000 nm. It should be noted that the cross-sectional diameter of the first groove 151 refers to the cross-sectional dimension of the first groove 151 in the first passivation layer 140 near the first electrode 150. Furthermore, the first groove 151 can be a groove of constant diameter or a groove of varying diameter.

[0059] In some embodiments, the connection between the first electrode 150 and the N-type doped layer 130 comprises a plurality of connection protrusions 152. In embodiments of the present application, the plurality of connection protrusions 152 are formed at the connection between the first electrode 150 and the N-type doped layer 130 to effectively ensure the stability of the connection between the first electrode 150 and the N-type doped layer 130. Specifically, the connection protrusions 152 may be provided only within the connection groove 131, for example, evenly distributed over the portion of the surface of the first electrode 150 located within the connection groove 131. In some embodiments, the connection protrusions 152 are spherical in shape.

[0060] In some embodiments, the diameter of the connecting protrusion 152 is 10 nm to 500 nm, for example, it can be 10 nm, 20 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm or any value therebetween.

[0061] In the embodiment of the present application, the diameter of the connecting protrusion 152 is controlled to ensure the contact stability between the first electrode 150 and the N-type doping layer 130 without affecting the effect of the N-type doping layer 130 .

[0062] In some embodiments, adjacent connecting protrusions 152 are tangential or spaced apart.

[0063] In some embodiments, a P-type doped layer 160 and a second passivation layer 170 are stacked in sequence on the front side of the silicon substrate 110 in a direction away from the silicon substrate 110, and a second electrode 180 is provided on the surface of the second passivation layer 170 away from the P-type doped layer 160. The second electrode 180 passes through the second passivation layer 170 and is connected to the P-type doped layer 160.

[0064] In some embodiments, the thickness of the P-type doped layer 160 is 0.2 μm to 1.5 μm, for example, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm or 1.5 μm.

[0065] In some embodiments, the second passivation layer 170 may be a silicon nitride (SiNx) layer. Optionally, the second passivation layer 170 has a thickness of 70 nm to 90 nm, for example, 70 nm, 75 nm, 80 nm, 85 nm, or 90 nm.

[0066] In some embodiments, an aluminum oxide layer 190 is further provided between the P-type doped layer 160 and the second passivation layer 170. Optionally, the aluminum oxide layer 190 has a thickness of 8 nm to 12 nm, for example, 8 nm, 9 nm, 10 nm, 11 nm or 12 nm.

[0067] In some embodiments, the second electrode 180 may be a gold electrode, a copper electrode, or a silver electrode, for example, a silver electrode.

[0068] In some embodiments, the first electrode 150 may be a gold electrode, a copper electrode, or a silver electrode, for example, a silver electrode. Correspondingly, the back electrode 150 is in contact with the N-type doped layer 130 via a connection protrusion 152 formed by a plurality of silver crystal particles.

[0069] In some embodiments, the solar cell 100 is a TOPCon cell, and the oxide layer 120 is a tunneling oxide layer 120. The tunneling oxide layer 120 and the N-type doped layer 130 together constitute a passivation contact structure on the back side of the TOPCon cell.

[0070] The present embodiment further provides a method for preparing the solar cell 100, including:

[0071] S1, cleaning and texturing the silicon substrate 110;

[0072] S2, performing boron diffusion on the silicon substrate 110 to form a borosilicate glass (BSG) layer on the surface of the silicon substrate 100, and performing boron doping on the front surface of the silicon substrate 110 by laser doping to form a P-type doped layer 160 on the front surface of the silicon substrate 110;

[0073] S3, performing diffusion oxidation on the silicon substrate 110 processed in step S2;

[0074] S4, removing the BSG layer on the back side of the silicon substrate 110;

[0075] S5, polishing the back side of the silicon substrate 110;

[0076] S6, depositing an oxide layer 120 and an N-type doping layer 130 in sequence on the back side of the silicon substrate 110;

[0077] S7, removing the N-type doping layer 130 on the front surface of the silicon substrate 110;

[0078] S8, annealing the polysilicon on the silicon substrate 110 to crystallize the polysilicon;

[0079] S9, performing film coating on the front side and the back side of the silicon substrate 110 to form a second passivation layer 170 and a first passivation layer 140 respectively;

[0080] S10, printing electrode paste on the surface of the first passivation layer 140, and sintering it after drying to form the first electrode 150; printing electrode paste on the second passivation layer 170, and sintering it after drying to form the second electrode 180; wherein, the electrode pastes of the first electrode 150 and the second electrode 180 can be the same or different, and those skilled in the art can reasonably select and adjust according to actual needs.

[0081] The raw materials used in the following examples and comparative examples are commercially available products unless otherwise specified; conventional technical means are used to prepare each layer structure.

[0082] In the following embodiments and comparative examples, the thickness of the silicon substrate 110 is 130 nm; the thickness of the oxide layer 120 is 4 nm; the thickness of the N-type doping layer 130 is 110 nm; the thickness of the P-type doping layer 160 is 0.25 μm; the thickness of the first passivation layer 140 is 80 nm, the thickness of the second passivation layer 170 is 85 nm, the first electrode 150 is formed by sintering metallization using pure silver paste, and the second electrode 180 is formed by sintering metallization using silver-aluminum paste, and the mass proportion of aluminum in the silver-aluminum paste is 2%; the thickness of the aluminum oxide layer 190 is 10 nm.

[0083] Example 1

[0084] This embodiment provides a solar cell 100, comprising a silicon substrate 110, and an oxide layer 120, an N-type doping layer 130, a first passivation layer 140, and a first electrode 150 sequentially disposed on a back side of the silicon substrate 110;

[0085] A plurality of first grooves 151 are provided on the first passivation layer 140. The cross-sectional shape of the first grooves 151 is a circle with a diameter of 3000 nm. The first grooves 151 pass through the upper and lower surfaces of the first passivation layer 140. The first electrode 150 fills the first grooves 151 and is electrically connected to the N-type doped layer 130. The connection between the first electrode 150 and the N-type doped layer 130 has a plurality of connection protrusions 152. The diameter of the connection protrusions 152 is 250 nm. In addition, the N-type doped layer 130 has a plurality of connection grooves 131. The connection grooves 131 correspond to the positions of the first grooves 151. The first electrode 150 fills the connection grooves 131 and is connected to the N-type doped layer 130. The ratio of the depth of the connection grooves 131 to the thickness of the N-type doped layer 130 is 0.1.

[0086] A P-type doped layer 160 and a second passivation layer 170 are stacked in sequence on the front side of the silicon substrate 110 in a direction away from the silicon substrate 110 . A second electrode 180 is provided on the surface of the second passivation layer 170 away from the P-type doped layer 160 . The second electrode 180 passes through the second passivation layer 170 and is connected to the P-type doped layer 160 .

[0087] The area of ​​the first groove 151 is 55% of the area of ​​the first electrode 150 ; and the spacing between adjacent first grooves 151 is 500 nm.

[0088] Example 2

[0089] This embodiment provides a solar cell 100. Compared with Example 1, the only difference is that the cross-sectional diameter of the first groove 151 is 1000 nm; the projected area of ​​the first electrode 150 in the first groove 151 is 30% of the area of ​​the first groove 151; the spacing between adjacent first grooves 151 is 1000 nm; the ratio of the depth of the connecting groove to the thickness of the N-type doped layer 130 is 0.02; and the diameter of the connecting protrusion 152 is 10 nm.

[0090] Example 3

[0091] This embodiment provides a solar cell 100. Compared with Example 1, the only difference is that the cross-sectional diameter of the first groove 151 is 5000 nm; the projected area of ​​the first electrode 150 in the first groove 151 is 80% of the area of ​​the first groove 151; the spacing between adjacent first grooves 151 is 5 nm; the ratio of the depth of the connecting groove to the thickness of the N-type doped layer 130 is 0.2; and the diameter of the connecting protrusion 152 is 500 nm.

[0092] Example 4

[0093] This embodiment provides a solar cell 100 . Compared with the first embodiment, the only difference is that the area of ​​the first groove 151 is 90% of the area of ​​the first electrode 150 .

[0094] Example 5

[0095] This embodiment provides a solar cell 100 . Compared with the embodiment 1, the only difference is that the area of ​​the first groove 151 is 20% of the area of ​​the first electrode 150 .

[0096] Example 6

[0097] This embodiment provides a solar cell 100 , which is different from the first embodiment in that the spacing distance between adjacent first grooves 151 is 1500 nm.

[0098] Example 7

[0099] This embodiment provides a solar cell 100 , which is different from the embodiment 1 only in that the diameter of the connecting protrusion 152 is 700 nm.

[0100] Comparative Example 1

[0101] This comparative example provides a solar cell 100 , which is different from Example 1 only in that the ratio of the depth of the connecting groove 131 to the thickness of the N-type doping layer 130 is 0.3.

[0102] Comparative Example 2

[0103] This comparative example provides a solar cell 100. Compared to Example 1, the only difference is that the first groove 151 penetrates the first passivation layer 140, and the ratio of the depth of the connection groove 131 to the thickness of the N-type doped layer 130 is 0.3. The area of ​​the first groove 151 is 70% of the area of ​​the first electrode 150, and the distance between adjacent first grooves 151 is 600 nm.

[0104] The solar cells 100 prepared in the above embodiments and comparative examples were tested for photoelectric conversion efficiency, open circuit voltage and fill factor using an IV tester according to IEC 60904 standard. The test results are shown in Table 1.

[0105] Table 1

[0106] From the table above we can see that:

[0107] (1) Compared with Comparative Examples 1-2, Example 1 shows that by controlling the depth of the connection groove 131, a contact connection with the N-type doped layer 130 is achieved. If the depth of the connection groove 131 is relatively large, the electrode paste may corrode a large area of ​​the N-type doped layer 130 during the preparation of the solar cell 100, affecting the passivation effect formed by the N-type doped layer 130 and the oxide layer 120. Furthermore, the first electrode 150 is embedded in and penetrates the first passivation layer 140 on the back side to achieve a connection with the N-type doped layer 130, thereby improving the matching effect between the first electrode 150 and the solar cell 100, avoiding damage to the passivation effect formed by the oxide layer 120 and the N-type doped layer 130, and effectively improving the photoelectric conversion efficiency of the solar cell 100.

[0108] (2) Compared with Examples 4-5, Example 1 shows that by controlling the area of ​​the first groove 151, the first electrode 150 and the first passivation layer 140 have good bonding stability, effectively ensuring that the back first electrode 150 can be embedded in the first passivation layer 140 and can be in stable contact with the N-type doped layer 130, thereby further improving the photoelectric conversion efficiency of the solar cell 100.

[0109] (3) Compared with Example 6, it can be seen that by controlling the spacing distance between the first grooves 151, the bonding stability of the back electrode 150 can be further improved, while avoiding causing the N-type doped layer 130 to be corroded over a large area during the preparation process of the solar cell 100, thereby affecting the passivation effect between the N-type doped layer 130 and the oxide layer 120.

[0110] (4) Comparing Example 1 with Example 7, it can be seen that by controlling the diameter of the connecting protrusion 152 , the contact stability between the first electrode 150 and the N-type doping layer 130 can be further ensured without affecting the effect of the N-type doping layer 130 .

[0111] Through the above embodiments and comparative examples, it can be seen that the back electrode structure of the solar cell 100 according to the embodiment of the present application can increase the open circuit voltage by 1mV to 3mV, the fill factor by 0.1% to 0.5%, and the overall photoelectric conversion efficiency by about 0.2%.

[0112] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0113] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A solar cell, characterized in that: The solar cell comprises a silicon substrate, and an oxide layer, an N-type doping layer, a first passivation layer and a first electrode which are sequentially arranged on the back side of the silicon substrate; A plurality of first grooves are formed on the first passivation layer, the first grooves penetrate the upper and lower surfaces of the first passivation layer, the first electrodes fill the first grooves and are electrically connected to the N-type doped layer; The N-type doped layer is provided with a plurality of connection grooves, the connection grooves corresponding to the positions of the first grooves, the first electrodes are filled into the connection grooves and connected to the N-type doped layer, and the ratio of the depth of the connection grooves to the thickness of the N-type doped layer is greater than 0 and less than or equal to 0.

2.

2. The solar cell according to claim 1, wherein: The ratio of the depth of the connection groove to the thickness of the N-type doping layer is 0.02-0.

18.

3. The solar cell according to claim 1 or 2, characterized in that: The ratio of the depth of the connection groove to the thickness of the N-type doping layer is 0.02-0.

1.

4. The solar cell according to any one of claims 1 to 3, characterized in that: The first slot area is 30% to 80% of the first electrode area.

5. The solar cell according to any one of claims 1 to 4, characterized in that: The spacing distance between adjacent first openings is 5 nm to 1000 nm.

6. The solar cell according to any one of claims 1 to 5, characterized in that: The thickness of the first passivation layer is 75 nm to 90 nm.

7. The solar cell according to any one of claims 1 to 6, characterized in that: The thickness of the N-type doping layer is 80nm-130nm.

8. The solar cell according to any one of claims 1 to 7, characterized in that: The cross-section of the first slot is circular or elliptical.

9. The solar cell according to any one of claims 1 to 8, characterized in that: The cross-sectional diameter of the first groove is 5 nm to 5000 nm.

10. The solar cell according to any one of claims 1 to 9, characterized in that: A plurality of connection protrusions are provided at the connection between the first electrode and the N-type doping layer.

11. The solar cell according to claim 10, wherein: Adjacent connecting protrusions are tangent or separated.

12. The solar cell according to claim 10 or 11, characterized in that: The diameter of the connecting protrusion is 10nm to 500nm.

13. The solar cell according to any one of claims 10 to 12, characterized in that: The first electrode is a silver electrode, and the connecting protrusion is a silver crystal particle.

14. The solar cell according to any one of claims 1 to 13, characterized in that: A P-type doped layer and a second passivation layer are stacked in sequence on the front side of the silicon substrate in a direction away from the silicon substrate, a second electrode is arranged on a surface of the second passivation layer away from the P-type doped layer, and the second electrode penetrates the second passivation layer and is connected to the P-type doped layer.

15. The solar cell according to any one of claims 1 to 14, characterized in that: The solar cell is a TOPCon cell, and the oxide layer is a tunneling oxide layer.

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