Topcon solar cell, battery assembly and photovoltaic system

Abstract

A TOPCon solar cell (100), a battery assembly (200) and a photovoltaic system (1000). A silicon substrate (10) of the TOPCon solar cell (100) has a first surface (11) and a second surface (12), which are opposite each other. A first tunnel oxide layer (20), a first polarity-doped layer (30) and a first passivation layer (40) are sequentially stacked on the first surface (11), and a second polarity-doped layer (50) and a second passivation layer (60) are sequentially stacked on the second surface (12). A first metal electrode (70) is disposed on the first passivation layer (40), and a second metal electrode (80) is disposed on the second passivation layer (60). In the extension direction of the first metal electrode (70), several first barrier isolation layers (90) arranged at intervals are provided below the first metal electrode (70), the first metal electrode (70) being made of a fire-through paste. At positions corresponding to the first barrier isolation layers (90), the first metal electrode (70) fires through the first passivation layer (40) to come into contact with the first barrier isolation layers (90); between two adjacent first barrier isolation layers (90), the first metal electrode (70) fires through the first passivation layer (40) to come into contact with the first polarity-doped layer (30); and the first barrier isolation layers (90) are obtained by partially removing an over-coated layer formed on the first polarity-doped layer (30) during the process of forming the second polarity-doped layer (50).

Description

Topcon solar cells, battery modules and photovoltaic systems

[0001] Priority information

[0002] This application claims priority and benefits of patent application No. 202323527045.8 filed with the State Intellectual Property Office of China on December 22, 2023, and the entire text of which is incorporated herein by reference. Technical Field

[0003] The present application relates to the technical field of solar cell panels, and in particular to a Topcon solar cell, a battery assembly, and a photovoltaic system. Background Art

[0004] Currently, in Topcon solar cells, there are doped layers on both the front and back sides of the silicon wafer, and the polarities of the two doped layers are opposite. At the same time, passivation layers and auxiliary grids are provided on both the front and back sides.

[0005] In the related art, the secondary gate is typically made using a burn-through paste. During the printing process to form the electrode, the secondary gate paste burns through the passivation layer and directly contacts the underlying doped layer. However, at the secondary gate location, the burn-through paste typically burns through the entire passivation layer, contacting the entire doped layer below. This means that the secondary gate is in full contact with the doped layer, and cannot selectively burn through the passivation layer. Summary of the Invention

[0006] The present application provides a Topcon solar cell, a battery string, a battery assembly and a photovoltaic system.

[0007] This application is implemented as follows: the Topcon solar cell of the embodiment of this application includes:

[0008] a silicon substrate having a first side and a second side opposite to each other;

[0009] A first tunneling oxide layer, a first polarity doping layer, and a first passivation layer are sequentially stacked on the first surface;

[0010] A second polarity doped layer and a second passivation layer are sequentially stacked on the second surface, wherein the second polarity doped layer has a polarity opposite to that of the first polarity doped layer;

[0011] a first metal electrode and a second metal electrode, wherein the first metal electrode is disposed on the first passivation layer, and the second metal electrode is disposed on the second passivation layer;

[0012] Wherein, in the extension direction of the first metal electrode, a plurality of first blocking isolation layers are arranged at intervals below the first metal electrode, the first blocking isolation layers are located between the first passivation layer and the first polarity doped layer, and the first metal electrode is made of a burn-through paste;

[0013] At a position corresponding to the first blocking isolation layer, the first metal electrode burns through the first passivation layer and contacts the first blocking isolation layer; between two adjacent first blocking isolation layers, the first metal electrode burns through the first passivation layer and contacts the first polarity doped layer; and the second metal electrode at least partially penetrates the second passivation layer and contacts the second polarity doped layer;

[0014] The first blocking isolation layer is obtained by partially removing a wrap-around layer formed on the first polarity doping layer during the process of forming the second polarity doping layer.

[0015] Furthermore, in the extension direction of the first metal electrode, a ratio of a length of the first metal electrode in contact with the first polarity doping layer to a total length of the first metal electrode is 30%-80%.

[0016] Furthermore, in the extension direction of the first metal electrode, a ratio of a length of the first metal electrode in contact with the first polarity doping layer to a total length of the first metal electrode is 40%-60%.

[0017] Furthermore, the first blocking isolation layer includes an insulating isolation layer stacked on the first polarity doping layer and a blocking doping layer stacked on the insulating isolation layer. At a position corresponding to the first blocking isolation layer, the first metal electrode burns through the first passivation layer and contacts the blocking doping layer, and the polarity of the blocking doping layer is the same as that of the second polarity doping layer.

[0018] Furthermore, the first polarity doped layer is a P-type doped layer, and the second polarity doped layer and the barrier doped layer are both N-type doped layers.

[0019] Furthermore, the bonding tension between the first metal electrode and the blocking doped layer is greater than the bonding tension between the first metal electrode and the first polarity doped layer; and / or

[0020] The bonding tension between the barrier doping layer and the first passivation layer is greater than the bonding tension between the first polarity doping layer and the first passivation layer.

[0021] Furthermore, the Topcon solar cell further includes a solder joint connected to the first metal electrode, wherein the solder joint is disposed on the first passivation layer and at least partially located above the barrier doping layer.

[0022] Furthermore, a projection area of ​​the blocking doping layer on the silicon substrate is greater than or equal to a projection area of ​​the solder joint on the silicon substrate, and the solder joint is completely located within the projection area of ​​the blocking doping layer.

[0023] Furthermore, the first surface has a plurality of first regions and second regions alternately arranged in sequence, the first polarity doped layer is arranged on the first region and does not cover the second region, and a plurality of first blocking isolation layers are provided above the first polarity doped layer on at least one of the first regions.

[0024] Furthermore, the area ratio of the first region to the first surface is less than 8%.

[0025] Furthermore, in the extension direction of the second metal electrode, at positions corresponding to the second metal electrode, a plurality of second blocking isolation layers are provided between the second polarity doped layer and the second passivation layer, and are spaced apart along the extension direction of the second metal electrode. The second metal electrode is also made of a fire-through paste.

[0026] At the position corresponding to the second blocking isolation layer, the second metal electrode burns through the second passivation layer and contacts the second blocking isolation layer. Between two adjacent second blocking isolation layers, the second metal electrode burns through the second passivation layer and contacts the second polarity doped layer. The second blocking isolation layer includes a phosphosilicate glass layer or a borosilicate glass layer.

[0027] Furthermore, a second tunneling oxide layer is provided between the second polarity doped layer and the second surface.

[0028] Furthermore, the second surface has a plurality of third regions and fourth regions that are alternately arranged in sequence, and the second polarity doped layer is arranged on the third region and does not cover the fourth region.

[0029] Furthermore, the area ratio of the third region to the second surface is greater than or equal to 30% and less than 100%.

[0030] The present application also provides a battery assembly, which includes several of the above-mentioned Topcon solar cells.

[0031] The present application also provides a photovoltaic system, which includes the above-mentioned battery assembly.

[0032] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG1 is a schematic structural diagram of a photovoltaic system provided in an embodiment of the present application.

[0034] FIG2 is a schematic diagram of the planar structure of a Topcon solar cell provided in an embodiment of the present application;

[0035] FIG3 is a schematic cross-sectional view of the Topcon solar cell along line III-III in FIG2 ;

[0036] FIG4 is a schematic cross-sectional view of the Topcon solar cell along line IV-IV in FIG2 ;

[0037] FIG5 is another cross-sectional schematic diagram of the Topcon solar cell along line III-III in FIG2 ;

[0038] FIG6 is another schematic cross-sectional view of the Topcon solar cell along line III-III in FIG2 ;

[0039] FIG7 is another cross-sectional schematic diagram of the Topcon solar cell along line III-III in FIG2 ;

[0040] FIG8 is another schematic cross-sectional view of the Topcon solar cell along line IV-IV in FIG2 .

[0041] Description of main component symbols:

[0042] Photovoltaic system 1000, battery assembly 200, Topcon solar cell 100, silicon substrate 10, first surface 11, second surface 12, first tunneling layer 20, first polarity doping layer 30, first passivation layer 40, second polarity doping layer 50, second passivation layer 60, first metal electrode 70, second metal electrode 80, first blocking isolation layer 90, insulating isolation layer 91, blocking doping layer 92, second blocking isolation layer 110, second tunneling oxide layer 120. Modes for Carrying Out the Invention

[0043] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below with reference to the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, in which the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. It should be noted that the embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and are not to be construed as limiting the present application. In addition, it should be understood that the specific embodiments described herein are merely used to explain the present application and are not intended to limit the present application.

[0044] In the description of this application, it should be understood that the terms "up", "down", "left", "right", "horizontal", "longitudinal", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on this application.

[0045] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more of the described features. In the description of this application, "several" means two or more, unless otherwise specifically defined.

[0046] In this application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0047] The disclosure below provides many different embodiments or examples for realizing different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present application. In addition, the present application may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those skilled in the art will appreciate the application of other processes and / or the use scenarios of other materials.

[0048] Example 1

[0049] Referring to FIG. 1 , a photovoltaic system 1000 in an embodiment of the present application may include a battery assembly 200 in an embodiment of the present application. The battery assembly 200 in an embodiment of the present application may include several Topcon solar cells 100 in an embodiment of the present application. The multiple Topcon solar cells 100 in the battery assembly 200 may be serially connected together via welding ribbons to form a battery string. The individual battery strings in the battery assembly 200 may be connected in series, in parallel, or in a combination of series and parallel to achieve current bus output. For example, bus bars may be used to connect the individual battery strings.

[0050] 2-4 , the Topcon solar cell 100 in the embodiment of the present application may include a silicon substrate 10, a first tunneling oxide layer 20, a first polarity doped layer 30, a first passivation layer 40, a second polarity doped layer 50, a second passivation layer 60, a first metal electrode 70, a second metal electrode 80 and a plurality of first blocking isolation layers 90.

[0051] The silicon substrate 10 has a first surface 11 and a second surface 12, which are opposite to each other and are respectively the front and back surfaces of the silicon substrate 10, and are not specifically limited herein. A first tunneling oxide layer 20, a first polarity doped layer 30, and a first passivation layer 40 are sequentially stacked on the first surface 11, and a second polarity doped layer 50 and a second passivation layer 60 are sequentially stacked on the second surface 12.

[0052] The first metal electrode 70 is disposed on the first passivation layer 40, and the second metal electrode 80 is disposed on the second passivation layer 60. As shown in FIG3 , a plurality of first barrier isolation layers 90 are disposed below the first metal electrode 70 in the direction in which the first metal electrode 70 extends. The first barrier isolation layers 90 are located between the first passivation layer 40 and the first polarity doped layer 30. The first metal electrode 70 is made of a fire-through paste.

[0053] At the position corresponding to the first barrier isolation layer 90, the first metal electrode 70 burns through the first passivation layer 40 and contacts the first barrier isolation layer 90. Between two adjacent first barrier isolation layers 90, the first metal electrode 70 burns through the first passivation layer 40 and contacts the first polarity doped layer 30. The second metal electrode 80 at least partially penetrates the second passivation layer 60 and contacts the second polarity doped layer 50. The first barrier isolation layer 90 is formed by partially removing the plating layer formed on the first polarity doped layer 30 during the formation of the second polarity doped layer 50. (It should be noted that since Figure 3 is a cross-sectional view along the extension direction of the first metal electrode 70, the first passivation layer 40 is essentially completely ablated at this position. Therefore, the first passivation layer 40 is not shown in Figure 3).

[0054] In the Topcon solar cell 100, the battery assembly 200 and the photovoltaic system 1000 in the embodiments of the present application, a plurality of first blocking isolation layers 90 are spaced apart along the extension direction of the first metal electrode 70 between the first polarity doping layer 30 and the first passivation layer 40. At positions corresponding to the first blocking isolation layers 90, the first metal electrode 70 burns through the first passivation layer 40 and contacts the first blocking isolation layer 90. Between two adjacent first blocking isolation layers 90, the first metal electrode 70 burns through the first passivation layer 40 and contacts the first polarity doping layer 30. The second metal electrode 80 at least partially penetrates the second passivation layer 60 and contacts the second polarity doping layer 50. In this way, in the process of using the burn-through paste to make the first metal electrode 70, the first metal electrode 70 will only burn through the first passivation layer 40 and contact the first polarity doping layer 30 at the gap between the first blocking isolation layer 90, and at the position corresponding to the first blocking isolation layer 90, it will only burn through the first passivation layer 40 and contact the first blocking isolation layer 90 without direct contact with the first polarity doping layer 30. In this way, selective burn-through of the burn-through paste can be achieved, which can reduce the metallized contact area between the first metal electrode 70 and the first polarity doping layer 30, reduce the recombination of the metallized area, and thus improve the conversion efficiency of the Topcon solar cell 100.

[0055] At the same time, the first blocking isolation layer 90 is obtained by partially removing the winding coating formed on the first polarity doping layer 30 during the process of forming the second polarity doping layer 50. In this way, there is no need to adopt other deposition means to form the first blocking isolation layer 90. It can be obtained by only partially removing the winding coating formed on the first polarity doping layer 30, which can save process.

[0056] It is not difficult to understand that after the first polarity doping layer 30 is formed, a wrap-around layer will be formed on the first polarity doping layer 30 during the process of making the second polarity doping layer 50. In the traditional technical solution, the wrap-around layer formed on the first polarity doping layer 30 needs to be completely removed, while in the present application, only the wrap-around layer is partially removed, and part of the wrap-around layer is retained to form the first blocking doping layer 90. In this way, there is no need to adopt an additional process to form the first blocking doping layer 90, which can save process steps.

[0057] In the present application, the first surface 11 and the second surface 12 can be the front and back sides of the silicon substrate 10 respectively, the silicon substrate 10 can be a P-type silicon substrate or an N-type silicon substrate, the first polarity doped layer 30 can be a P-type doped layer or an N-type doped layer, and one of the first metal electrode 70 and the second metal electrode 80 is a P-type electrode, and the other is an N-type electrode.

[0058] The first polarity doped layer 30 can be formed on the first surface 11 of the silicon wafer by deposition. Of course, in some embodiments, the first polarity doped layer 30 can also be formed on the silicon substrate 10 by diffusion. In this case, the substrate portion below the first polarity doped layer 30 formed by diffusion can be regarded as the silicon substrate 10.

[0059] It should be noted that, in the present application, the burn-through paste refers to a metal paste with strong burn-through capability, which can be a silver paste or a silver-aluminum paste, etc., and can completely burn through the first passivation layer 40 so that the first metal electrode 70 can contact the film layer below the first passivation layer 40. For example, in one possible embodiment, the glass powder content of the burn-through paste can be higher than that of a traditional paste, thereby providing it with stronger burn-through capability.

[0060] Example 2

[0061] Please refer to Figure 5. In some embodiments, the first blocking isolation layer 90 may include an insulating isolation layer 91 stacked on the first polarity doping layer 30 and a blocking doping layer 92 stacked on the insulating isolation layer 91. At a position corresponding to the first blocking isolation layer 90, the first metal electrode 70 burns through the first passivation layer 40 and contacts the blocking doping layer 92. The polarity of the blocking doping layer 92 is the same as the polarity of the second polarity doping layer 50.

[0062] Thus, the first blocking isolation layer 90 on the first polarity doped layer 30 includes an insulating isolation layer 91 and a blocking doped layer 92 . The insulating isolation layer 91 can prevent the blocking doped layer 92 from directly contacting the first polarity doped layer 30 and causing leakage.

[0063] In such an embodiment, the insulating isolation layer 91 may include at least one of a borosilicate glass layer, a phosphosilicate glass layer, and a borophosphosilicate glass layer, or a combination of multiple thereof.

[0064] Specifically, in the present application, the second polarity doping layer 50 can be formed on the second surface 12 by diffusion or deposition. The following describes in detail the two methods for forming the second polarity doping layer 50:

[0065] The first case: the second polarity doping layer 50 is formed by deposition. In this case, after the first polarity doping layer 30 is formed on the first surface 11, a wrap-around layer having a doping layer will be formed on the first polarity doping layer 30 during the process of depositing the second polarity doping layer 50.

[0066] When the first polarity doping layer 30 is a P-type doping layer and the second polarity doping layer 50 is an N-type doping layer, the winding coating layer includes a phosphosilicate glass layer and an N-type doping layer stacked on the phosphosilicate glass layer. In this way, the first blocking isolation layer 90 can be obtained by only partially removing the winding coating layer, and the phosphosilicate glass layer is the insulating isolation layer 91, and the N-type doping layer is the blocking doping layer 9292.

[0067] When the first polarity doping layer 30 is an N-type doping layer and the second polarity doping layer 50 is a P-type doping layer, the winding coating layer includes a borosilicate glass layer and a P-type doping layer stacked on the borosilicate glass layer. In this way, the first blocking isolation layer 90 can be obtained by only partially removing the winding coating layer, and the borosilicate glass layer is the insulating isolation layer 91, and the P-type doping layer is the blocking doping layer 9292.

[0068] Of course, it is understandable that in the process of forming the first polarity doping layer 30, a phosphosilicate glass layer or a borosilicate glass layer will be formed on the first polarity doping layer 30. If the phosphosilicate glass layer or the borosilicate glass layer is not removed before forming the second polarity doping layer 50, then a borosilicate glass layer will be formed in the process of forming the second polarity doping layer 50. In this case, the insulating isolation layer 91 is a borosilicate glass layer.

[0069] The second case: the second polarity doping layer 50 is formed by diffusion on the second surface 12. In this case, when the first polarity doping layer 30 is a P-type doping layer and the second polarity doping layer 50 is an N-type doping layer, the second polarity doping layer 50 can be formed by phosphorus diffusion on the second surface 12.

[0070] When the second polarity doped layer 50 is diffused to form, a phosphosilicate glass layer is formed on the first polarity doped layer 30. In this case, only the phosphosilicate glass layer in a localized area of ​​the first polarity doped layer 30 needs to be removed to form the first blocking isolation layer 90 on the first shielding area 212. In other words, the first blocking isolation layer 90 is a phosphosilicate glass layer. Of course, it is understood that during the formation of the first polarity doped layer 30, a borosilicate glass layer is formed on the first polarity doped layer 30. If the borosilicate glass layer is not removed before forming the second polarity doped layer 50, a borophosphosilicate glass layer will be formed during the formation of the second polarity doped layer 50. In this case, the first blocking isolation layer 90 is a borophosphosilicate glass layer.

[0071] Similarly, when the first polarity doped layer 30 is an N-type doped layer and the second polarity doped layer 50 is a P-type doped layer, the second polarity doped layer 50 can be formed by boron diffusion on the second surface 12. During the diffusion process to form the second polarity doped layer 50, a borosilicate glass layer is formed on the first polarity doped layer 30. In this case, it is only necessary to remove the borosilicate glass layer in a localized area of ​​the first polarity doped layer 30 to form the first blocking isolation layer 90 on the first shielding area 212. In other words, the first blocking isolation layer 90 is a borosilicate glass layer. Of course, it is understood that during the formation of the first polarity doped layer 30, a phosphosilicate glass layer is formed on the first polarity doped layer 30. If the phosphosilicate glass layer is not removed before forming the second polarity doped layer 50, a borophosphosilicate glass layer is formed during the formation of the second polarity doped layer 50. In this case, the first blocking isolation layer 90 is a borophosphosilicate glass layer.

[0072] Example 3

[0073] Referring to FIG. 1 , in some embodiments, in the first predetermined direction, a ratio of a length of the first metal electrode 70 in contact with the first polarity doping layer 30 to a total length of the first metal electrode 70 is 30%-80%.

[0074] In this way, setting the contact length between the first metal electrode 70 and the first polarity doped layer 30 within the above-mentioned ratio range can effectively reduce the metallization contact area to reduce recombination while avoiding excessive resistance caused by too small a contact area. That is, the relationship between recombination and resistance can be balanced to improve the efficiency of the Topcon solar cell 100.

[0075] Specifically, in such an embodiment, the ratio between the length of the first metal electrode 70 in contact with the first polarity doping layer 30 and the total length of the first metal electrode 70 may be, for example, 30%, 40%, 50%, 60%, 70%, 80% or any value between 30% and 80%.

[0076] Furthermore, in such an embodiment, after careful research and derivation by the inventors of the present application, it was discovered that in order to maximize the balance between metallization recombination and resistance while improving the conversion efficiency of the Topcon solar cell 100 as much as possible, the ratio of the length of the first metal electrode 70 in contact with the first polarity doping layer 30 to the total length of the first metal electrode 70 may preferably be in the range of 40%-60%, for example, 40%, 45%, 50%, 55%, 60% and any value between 40%-60%.

[0077] Example 4

[0078] In some embodiments, the first polarity doping layer 30 may be a P-type doping layer, and the blocking doping layer 92 and the second polarity doping layer 50 may both be N-type doping layers.

[0079] In this way, when the blocking doping layer 92 on the P-type doping layer is an N-type doping layer, by setting the N-type doping layer on the P-type doping layer, the bonding tension between the first passivation layer 40 and the N-type doping layer is greater than the bonding tension between the passivation layer and the P-type doping layer. When the solder joints are subsequently set, the welding tension of the solder joints during welding can be effectively increased, thereby effectively avoiding the detachment of the solder joints during welding and improving the reliability of welding.

[0080] Example 5

[0081] In some embodiments, the bonding tension between the first metal electrode 70 and the blocking doping layer 92 is greater than the bonding tension between the first metal electrode 70 and the first polarity doping layer 30 .

[0082] In this way, the provision of the blocking doping layer 92 can improve the stability of the first metal electrode 70 and effectively prevent the first metal electrode 70 from being deflected or falling off.

[0083] Example 6

[0084] In some embodiments, the bonding tension between the blocking doping layer 92 and the first passivation layer 40 is greater than the bonding tension between the first polarity doping layer 30 and the first passivation layer 40 .

[0085] In this way, the bonding tension between the blocking doping layer 92 and the first passivation layer 40 is relatively large, which can effectively increase the tension of the solder joints provided on the first passivation layer 40 and prevent the solder joints from falling off during welding.

[0086] Specifically, in such an embodiment, the first polarity doped layer 30 is a P-type doped layer, the blocking doped layer 92 is an N-type blocking layer, and the bonding tension between the N-type doped layer and the first passivation layer 40 is greater than the tension between the P-type doped layer and the first passivation layer 40.

[0087] Furthermore, in such embodiments, in some embodiments, the Topcon solar cell 100 further includes a solder joint (not shown) connected to the first metal electrode 70 , which is disposed on the first passivation layer 40 and at least partially above the blocking doping layer 92 .

[0088] In this way, disposing the solder joint at least partially above the blocking doping layer 92 can increase the soldering tension of the solder joint during soldering.

[0089] Furthermore, in some embodiments, the solder joint at least partially burns through the first passivation layer 40 and contacts the blocking doping layer 92 , and the bonding tension between the solder joint and the blocking doping layer 92 is greater than the bonding tension between the solder joint and the first polarity doping layer 30 .

[0090] In this way, the bonding tension between the solder joint and the blocking doping layer 92 is greater, and the welding tension of the solder joint during welding can also be effectively improved.

[0091] Specifically, in such an embodiment, the solder joint may be a P-type solder joint, and the paste used to form the solder joint may be the same as or different from the paste used to form the first metal electrode 70 , which is not specifically limited herein.

[0092] Example 7

[0093] In some embodiments, the projection area of ​​the blocking doping layer 92 on the silicon substrate 10 is greater than or equal to the projection area of ​​the solder joint on the silicon substrate 10 , and the solder joint is completely located within the projection area of ​​the blocking doping layer 92 .

[0094] In this way, the solder joint is completely located in the area where the first barrier doping layer 92 is located, and the entire area below the solder joint is covered with the barrier doping layer 92 . This can maximize the soldering tension at the solder joint, thereby ensuring soldering reliability.

[0095] Specifically, in such an embodiment, the area of ​​the blocking doping layer 92 may preferably be just equal to the projected area of ​​the solder joint or slightly larger than the projected area of ​​the solder joint, which is not specifically limited here.

[0096] Example 8

[0097] Referring to Figures 6 and 7 , in some embodiments, a plurality of second blocking isolation layers 110 are disposed between the second polarity doped layer 50 and the second passivation layer 60 at locations corresponding to the second metal electrode 80 in the extension direction of the second metal electrode 80. The second metal electrode 80 is also made of a burn-through paste. At locations corresponding to the second blocking isolation layers 110, the second metal electrode 80 burns through the second passivation layer 60 to contact the second blocking isolation layers 110. Between two adjacent second blocking isolation layers 110, the second metal electrode 80 burns through the second passivation layer 60 to contact the second polarity doped layer 50. The second blocking isolation layers 110 include phosphosilicate glass layers or borosilicate glass layers. In this embodiment, the extension direction of the first metal electrode 70 can be the same as the extension direction of the second metal electrode 80.

[0098] In this way, by setting the second blocking isolation layer 110, in the process of manufacturing the second metal electrode 80, the second metal electrode 80 partially burns through the second passivation layer 90 and contacts the second polarity doping layer 50, while at the second blocking isolation layer 110, only the second passivation layer 90 will be burned through and contact the second blocking isolation layer 110, and there will be no direct contact with the second polarity doping layer 50. In this way, selective burning of the burn-through paste can be achieved, the metallized contact area between the second metal electrode 80 and the second polarity doping layer 50 can be reduced, the recombination of the metallized area can be reduced, and the conversion efficiency of the Topcon solar cell 100 can be further improved.

[0099] Specifically, in such an embodiment, the second polarity doping layer 50 can be formed by deposition or diffusion. When the second polarity doping layer 50 is an N-type doping layer, a phosphosilicate glass layer will be formed on the second polarity doping layer 50 during the process of forming the second polarity doping layer 50. In the subsequent removal process, the phosphosilicate glass layer at the second blocking area 812 of the second polarity doping layer 50 is retained to form the second blocking isolation layer 110, that is, the second blocking isolation layer 110 is a phosphosilicate glass layer.

[0100] When the second polarity doped layer 50 is a P-type doped layer, a borosilicate glass layer will be formed on the second polarity doped layer 50 during the process of forming the second polarity doped layer 50. In the subsequent removal process, the borosilicate glass layer at the second blocking area 812 of the second polarity doped layer 50 is retained to form the second blocking isolation layer 110, that is, the second blocking isolation layer 110 is a borosilicate glass layer.

[0101] Embodiment 9

[0102] Please refer to Figure 7. In some embodiments, a second tunneling oxide layer 120 may be provided between the second polarity doped layer 50 and the second surface 12. In this way, the second tunneling oxide layer 120 can achieve a tunneling passivation function on the second surface 12 and enhance the passivation effect of the second surface 12.

[0103] Specifically, in such an embodiment, when the Topcon solar cell 100 has only the first tunneling layer 60, the Topcon solar cell 100 is a single-sided Topcon solar cell. When the Topcon solar cell 100 has both the first tunneling layer 60 and the second tunneling oxide layer 120, the Topcon solar cell 100 can also be a double-sided Topcon solar cell, without limitation herein. The first tunneling layer 60 and the second tunneling oxide layer 120 can both be tunneling silicon oxide layers.

[0104] Example 10

[0105] Please refer to Figure 8. In some embodiments, the first surface 11 has a plurality of first regions 111 and second regions 112 that are alternately arranged in sequence, the first polarity doped layer 30 is arranged on the first region 111 and does not cover the second region 112, and a plurality of first blocking isolation layers 90 are provided above the first polarity doped layer 30 on at least one first region 111.

[0106] In this way, the first polarity doped layer 30 only covers the first area 111 of the first surface 11 and does not cover the second area 112. The first surface 11 of the silicon substrate 10 is not completely covered by the first polarity doped layer 30, which can effectively reduce the parasitic absorption of light by the first polarity doped layer 30 and improve the conversion efficiency.

[0107] Furthermore, in some embodiments, the silicon substrate 10 may preferably be a P-type silicon substrate 10, the first surface 11 is the light-facing surface, the second surface 12 is the backlight surface, the first polarity doped layer 30 is a P-type doped layer, and the second polarity doped layer 50 is an N-type doped layer.

[0108] In this way, on the one hand, a P-type silicon substrate 10 is used, and the preparation technology of the P-type silicon substrate 10 is more mature than that of the N-type substrate; on the other hand, a P-type doping layer that only covers the first area 111 is used on the light-facing surface of the P-type silicon substrate 10. Since the P-type doping layer has a poor passivation effect on the P-type silicon substrate 10, the P-type doping layer is only set on the first area 111 for local passivation, and the second area 112 is directly passivated using the first passivation layer 40, which has better passivation performance and can improve the passivation effect of the first surface 11, thereby improving the electrical performance of the solar cell and further improving the efficiency.

[0109] In some embodiments, the thickness of the second polarity doping layer 50 is less than the thickness of the first polarity doping layer 30 .

[0110] Thus, when the silicon substrate 10 is a P-type silicon substrate 10 and the first polarity doped layer 30 is a P-type doped layer, setting the thickness of the first polarity doped layer 30 to be thicker can improve the passivation effect of the first surface 11 and thereby enhance the electrical performance of the cell.

[0111] In some embodiments, both the first polarity doped layer 30 and the second polarity doped layer 50 may include doped semi-insulating polysilicon layers. Thus, the materials of both the first polarity doped layer 30 and the second polarity doped layer 50 are semi-insulating polysilicon, which has less parasitic absorption than traditional polysilicon. In other words, using such materials can reduce parasitic absorption and improve conversion efficiency.

[0112] Example 11

[0113] In some embodiments, the ratio of the area of ​​the first region 111 to the area of ​​the first surface 11 (ie, the area proportion of the first region 111 ) is less than 8%.

[0114] Thus, setting the area ratio of the first region 111 to the first surface 11 to be less than 8% can greatly reduce the area proportion of the first polarity doped layer 30 , thereby reducing parasitic absorption of the first polarity doped layer 30 and improving efficiency.

[0115] At the same time, when the silicon substrate 10 is a P-type silicon substrate 10, the first polarity doped layer 30 is a P-type doped layer, and the first surface 11 is a light-facing surface, the area of ​​the first region 111 is set to be smaller, and the area of ​​the second region 112 can be increased, thereby improving the passivation effect of the first surface 11, that is, the passivation effect of the first surface 11 can be improved while reducing parasitic absorption, thereby improving efficiency.

[0116] Furthermore, in such an embodiment, the ratio of the area of ​​the first region 111 to the area of ​​the first surface 11 is preferably less than 6%, and most preferably less than 5%.

[0117] Example 12

[0118] 8 , in some embodiments, the second surface 12 may have a plurality of third regions 121 and fourth regions 122 alternately arranged in sequence, and the second polarity doped layer 50 is disposed on the third region 121 and does not cover the fourth region 122 .

[0119] Thus, the second polarity doped layer 50 only covers the third region 121 of the second surface 12 and does not cover the fourth region 122. Thus, the second surface 12 of the silicon substrate 10 is not completely covered by the second polarity doped layer 50, which can effectively reduce the parasitic absorption of light by the second polarity doped layer 50 and improve conversion efficiency.

[0120] In some embodiments, the ratio of the area of ​​the third region 121 to the area of ​​the second surface 12 is greater than or equal to 30% and less than 100%.

[0121] In this way, when the silicon substrate 10 is a P-type silicon substrate 10, the second polarity doped layer 50 is an N-type doped layer, and the second surface 12 is a backlight surface, the area of ​​the third region 121 of the second surface 12 is set to be larger, which can ensure the area ratio of the N-type doped layer while reducing parasitic absorption, balance the passivation contact area and parasitic absorption, and thus improve the conversion efficiency.

[0122] Furthermore, in such an embodiment, the ratio of the area of ​​the third region 121 to the area of ​​the second surface 12 is preferably greater than or equal to 40% and less than 100%. Still further, in such an embodiment, the ratio of the area of ​​the third region 121 to the area of ​​the second surface 12 is more preferably greater than or equal to 50% and less than 100%, and most preferably greater than or equal to 60% and less than 100%.

[0123] Throughout this specification, reference to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0124] In addition, the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A Topcon solar cell, characterized in that: include: A silicon substrate having a first surface and a second surface opposite to each other; A first tunneling oxide layer, a first polarity doping layer and a first passivation layer are sequentially stacked on the first surface; A second polarity doping layer and a second passivation layer are sequentially stacked on the second surface, wherein the second polarity doping layer has a polarity opposite to that of the first polarity doping layer; a first metal electrode and a second metal electrode, wherein the first metal electrode is disposed on the first passivation layer, and the second metal electrode is disposed on the second passivation layer; Wherein, in the extension direction of the first metal electrode, a plurality of first blocking isolation layers arranged at intervals are provided below the first metal electrode, the first blocking isolation layers are located between the first passivation layer and the first polarity doping layer, and the first metal electrode is made of a burn-through slurry; At a position corresponding to the first blocking isolation layer, the first metal electrode burns through the first passivation layer and contacts the first blocking isolation layer, between two adjacent first blocking isolation layers, the first metal electrode burns through the first passivation layer and contacts the first polarity doped layer, and the second metal electrode at least partially penetrates the second passivation layer and contacts the second polarity doped layer; The first blocking isolation layer is obtained by partially removing a wrap-around layer formed on the first polarity doping layer during the process of forming the second polarity doping layer.

2. The Topcon solar cell according to claim 1, characterized in that: In the extension direction of the first metal electrode, a ratio between a length of the first metal electrode in contact with the first polarity doping layer and a total length of the first metal electrode is 30%-80%.

3. The Topcon solar cell according to claim 2, characterized in that: In the extension direction of the first metal electrode, a ratio between a length of the first metal electrode in contact with the first polarity doping layer and a total length of the first metal electrode is 40%-60%.

4. The Topcon solar cell according to claim 1, characterized in that: The first blocking isolation layer includes an insulating isolation layer stacked on the first polarity doping layer and a blocking doping layer stacked on the insulating isolation layer. At a position corresponding to the first blocking isolation layer, the first metal electrode burns through the first passivation layer and contacts the blocking doping layer. The polarity of the blocking doping layer is the same as that of the second polarity doping layer.

5. The Topcon solar cell according to claim 4, characterized in that: The first polarity doping layer is a P-type doping layer, and the second polarity doping layer and the blocking doping layer are both N-type doping layers.

6. The Topcon solar cell according to claim 5, characterized in that: The bonding tension between the first metal electrode and the barrier doping layer is greater than the bonding tension between the first metal electrode and the first polarity doping layer; and / or A bonding tension between the barrier doping layer and the first passivation layer is greater than a bonding tension between the first polarity doping layer and the first passivation layer.

7. The Topcon solar cell according to claim 6, characterized in that: The Topcon solar cell further includes a solder joint connected to the first metal electrode, wherein the solder joint is disposed on the first passivation layer and at least partially located above the barrier doping layer.

8. The Topcon solar cell according to claim 7, characterized in that: The projection area of ​​the blocking doping layer on the silicon substrate is greater than or equal to the projection area of ​​the solder joint on the silicon substrate, and the solder joint is completely located within the projection area of ​​the blocking doping layer.

9. The Topcon solar cell according to claim 1, characterized in that: The first surface has a plurality of first regions and second regions that are alternately arranged in sequence, the first polarity doping layer is arranged on the first region and does not cover the second region, and a plurality of first blocking isolation layers are arranged above the first polarity doping layer on at least one of the first regions.

10. The Topcon solar cell according to claim 9, characterized in that: A ratio of an area of ​​the first region to an area of ​​the first surface is less than 8%.

11. The Topcon solar cell according to claim 1, characterized in that: In the extension direction of the second metal electrode, at a position corresponding to the second metal electrode, a plurality of second blocking isolation layers are arranged between the second polarity doping layer and the second passivation layer and are arranged at intervals along the extension direction of the second metal electrode, and the second metal electrode is also made of a burn-through paste; At the position corresponding to the second blocking isolation layer, the second metal electrode burns through the second passivation layer and contacts the second blocking isolation layer. Between two adjacent second blocking isolation layers, the second metal electrode burns through the second passivation layer and contacts the second polarity doped layer. The second blocking isolation layer includes a phosphosilicate glass layer or a borosilicate glass layer.

12. The Topcon solar cell according to claim 11, characterized in that: A second tunneling oxide layer is disposed between the second polarity doped layer and the second surface.

13. The Topcon solar cell according to claim 11, characterized in that: The second surface has a plurality of third regions and fourth regions that are alternately arranged in sequence, and the second polarity doped layer is arranged on the third region and does not cover the fourth region.

14. The Topcon solar cell according to claim 13, characterized in that: A ratio of an area of ​​the third region to an area of ​​the second surface is greater than or equal to 30% and less than 100%.

15. A battery assembly, characterized in that: A Topcon solar cell comprising any one of claims 1-14.

16. A photovoltaic system, characterized in that: A battery assembly comprising the battery assembly of claim 15.

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