Back contact cell, cell assembly and photovoltaic system

Abstract

The utility model relates to the technical field of solar cells, and provides a back contact cell, a cell assembly and a photovoltaic system, and the back contact cell comprises a silicon substrate, a plurality of first doped layers and a plurality of second doped layers. The silicon substrate is provided with a front surface and a back surface which are opposite to each other, the back surface comprises first pole regions and second pole regions which are alternately arranged along a first direction, a sunken groove is formed in at least part of the first doped layer, and the second doped layer is provided with a leakage contact part extending to the first doped layer; the electric leakage contact part partially extends into the recessed groove and forms electric leakage contact with the first doping layer at least in the recessed groove. Therefore, the electric leakage contact part of the second doping layer can form electric leakage contact with the first doping layer in the sunken groove, so that an electric leakage point position is formed at the sunken groove, the reverse breakdown voltage when the back contact battery is shielded can be reduced, the hot spot resistance of the back contact battery is improved, and the hot spot risk of the battery assembly is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and particularly to a back-contact battery, a battery module, and a photovoltaic system. Background Art

[0002] Currently, in solar cells, a back-contact battery is a battery in which both the emitter and base contact electrodes are placed on the back surface (non-light-receiving surface) of the battery. There is no metal electrode shielding on the light-receiving surface of the battery, thus effectively increasing the short-circuit current of the cell.

[0003] In the related art, during the use of a back-contact battery, when an external obstacle blocks the cell, the blocked cell will exhibit a hot spot phenomenon. At a relatively high temperature, it is likely to cause carbonization of the encapsulation film of the module and even lead to a fire.

[0004] Therefore, how to improve the anti-hot spot performance of the back-contact battery has become a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Utility Model

[0005] The present application provides a back-contact battery, a battery module, and a photovoltaic system.

[0006] The back-contact battery according to the embodiments of the present application is implemented as follows:

[0007] A silicon substrate having opposite front and back surfaces, the back surface including a first pole region and a second pole region alternately arranged in a first direction, both the first pole region and the second pole region extending in a second direction, and the second direction intersecting the first direction;

[0008] A plurality of first doping layers disposed on the first pole region and covering at least a partial region of the first pole region, each first pole region being provided with a first doping layer, and at least a partial region of the first doping layer having an indented groove formed thereon; and

[0009] A plurality of second doping layers disposed on the second pole region and covering at least a partial region of the second pole region, each second pole region being provided with a second doping layer, at least a partial region of the second doping layer having a leakage contact portion extending onto the first doping layer, and the leakage contact portion partially extending into the indented groove, and the leakage contact portion being in leakage contact with the first doping layer at least within the indented groove.

[0010] In some embodiments, the first doping layer has opposite first and second side surfaces in the first direction, the indented groove does not penetrate the first and second side surfaces, and on both sides of the indented groove in the first direction, there is the first doping layer.

[0011] In some embodiments, the first doping layer has a first side surface and a second side surface opposite to each other in the first direction, and the sunken groove penetrates at least one of the first side surface and the second side surface.

[0012] In some embodiments, the recessed groove completely penetrates the first doped layer in a thickness direction of the first doped layer, so that the silicon substrate is exposed at the recessed groove;

[0013] The leakage contact portion covers the silicon substrate exposed from the sunken groove and covers at least a portion of the sidewall surface of the sunken groove.

[0014] In some embodiments, an inner expansion layer is formed in a portion of the silicon substrate corresponding to the first polar region, and the polarity of the inner expansion layer is the same as the polarity of the first doping layer;

[0015] Wherein, the sunken groove does not penetrate the inner expansion layer, and the leakage contact portion is in leakage contact with the inner expansion layer away from the surface of the silicon substrate; or

[0016] The sunken groove penetrates the inner expansion layer, and the leakage contact portion is in leakage contact with a side surface of the inner expansion layer exposed at the sunken groove.

[0017] In some embodiments, the recessed groove does not completely penetrate the first doped layer in the thickness direction of the first doped layer, and the leakage contact portion covers at least a portion of the bottom surface of the recessed groove and at least a portion of the sidewall surface of the recessed groove.

[0018] In some embodiments, the leakage contact portion includes a first portion located in the recessed groove and a second portion stacked on the surface of the first doped layer facing away from the silicon substrate; the first portion is in leakage contact with the first doped layer, and an insulating dielectric layer is provided between the second portion and the first doped layer.

[0019] In some embodiments, the leakage contact portion includes a first portion located in the recessed groove and a second portion stacked on the surface of the first doped layer away from the silicon substrate; the first portion is in leakage contact with the first doped layer, and the second portion is in leakage contact with the surface of the first doped layer away from the silicon substrate.

[0020] In some embodiments, in the first direction, the leakage contact portion extends along the side of the first doped layer to the surface of the first doped layer facing away from the silicon substrate and into the recessed groove, and the leakage contact portion also forms a leakage contact with the first doped layer at the side of the first doped layer.

[0021] In some embodiments, in the first direction, there is a first predetermined distance between the recessed groove and the side surface of the first doped layer, and the size of the first predetermined distance is 10 μm - 200 μm.

[0022] In some embodiments, in the first direction, the length of the recessed groove is 10 μm - 80 μm; and / or

[0023] In the second direction, the length of the recessed groove is less than 10 μm - 500 μm.

[0024] In some embodiments, the ratio of the length of the recessed groove in the second direction to the length of the recessed groove in the first direction is greater than or equal to 2.

[0025] In some embodiments, in the thickness direction of the first doped layer, the recessed groove does not completely penetrate the first doped layer, and the recessed depth of the recessed groove is 20 nm - 200 nm.

[0026] In some embodiments, on a single first doped layer, the number of the recessed grooves is multiple, and the multiple recessed grooves are arranged at intervals in the second direction.

[0027] In some embodiments, in the second direction, the distance between two adjacent recessed grooves is 1 cm - 10 cm.

[0028] In some embodiments, in the second direction, the distance between two adjacent recessed grooves is greater than or equal to 2 cm and less than 4 cm.

[0029] In some embodiments, the multiple recessed grooves are arranged in at least two columns in the second direction.

[0030] In some embodiments, in the back contact battery, the distribution density of the recessed grooves is 0.01 pieces / cm 2 -1.5 pieces / cm 2 。

[0031] In some embodiments, in a single recessed groove, the area of the leakage contact part in leakage contact with the first doped layer is 1.2 μm 2 -1500 μm 2 。

[0032] In some embodiments, in the back contact battery, the ratio of the sum of the areas of all the leakage contact parts in leakage contact with the first doped layer to the back area of the back contact battery is 4.5*10 -8 -1.5*10 -5 。

[0033] In some embodiments, the second pole region is a groove formed in the silicon substrate, the first doped layer has a first protrusion extending above the groove, and the leakage contact portion extends along the side wall surface of the groove to surround the first protrusion and extends onto the first doped layer and into the recessed groove.

[0034] In some embodiments, the second pole region is a groove formed in the silicon substrate, and the first doped layer does not completely cover the first pole region, so that the first pole region has an exposed area not covered by the first doped layer between the first doped layer and the groove, and the leakage contact portion extends to and covers the exposed area.

[0035] In some embodiments, the recessed groove completely penetrates the first doped layer in the thickness direction of the first doped layer and forms a trench on the silicon substrate, and the depression depth of the trench on the silicon substrate is 1 μm - 6 μm.

[0036] In some embodiments, the recessed groove completely penetrates the first doped layer in the thickness direction of the first doped layer and forms a trench on the silicon substrate, and the first doped layers on both sides of the trench both have second protrusions extending above the trench, and the leakage contact portion surrounds at least one of the second protrusions and extends into the recessed groove.

[0037] In some embodiments, the recessed groove completely penetrates the first doped layer in the thickness direction of the first doped layer and forms a trench on the silicon substrate, and in the first direction, the first doped layers on both sides of the trench and the edge of the trench have a second preset distance.

[0038] In some embodiments, the magnitude of the second preset distance is 0.3 μm - 50 μm.

[0039] In some embodiments, the magnitude of the second preset distance is 1 μm - 20 μm.

[0040] In some embodiments, the second pole region is a groove formed in the silicon substrate, and at the edge of the first doped layer facing the groove, the first doped layer forms a stepped structure, the leakage contact portion covers the stepped structure, and the leakage contact portion makes a leakage contact with the first doped layer at the stepped structure.

[0041] In some embodiments, within the first pole region, a first dielectric layer is provided between the first doped layer and the silicon substrate, and within the second pole region, a second dielectric layer is provided between the second doped layer and the silicon substrate.

[0042] In some embodiments, a dielectric layer is provided on the region in the recessed groove covered by the leakage contact portion, the leakage contact portion covers the dielectric layer, and the leakage contact portion makes a leakage contact with the first doped layer through the dielectric layer in the recessed groove.

[0043] The present application also provides a battery assembly, which includes a plurality of back contact batteries as described in any one of the above.

[0044] The present application also provides a photovoltaic system, which includes the battery assembly as described above.

[0045] In the back contact battery, battery assembly and photovoltaic system according to the embodiments of the present application, a recessed groove is formed on at least part of the first doped layer, the second doped layer has a leakage contact portion extending to the first doped layer, and the leakage contact portion partially extends into the recessed groove and makes a leakage contact with the first doped layer at least in the recessed groove. In this way, the leakage contact portion of the second doped layer can make a leakage contact with the first doped layer in the recessed groove, so as to form a leakage point at the recessed groove, which can reduce the reverse breakdown voltage when the back contact battery is shaded, thereby improving the anti-thermal spot performance of the back contact battery and reducing the thermal spot risk of the battery assembly.

[0046] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. Description of the Drawings

[0047] Figure 1 is a schematic module diagram of a photovoltaic system provided by an embodiment of the present application;

[0048] Figure 2 is a schematic module diagram of a battery assembly provided by an embodiment of the present application;

[0049] Figure 3 is a schematic plan view of a back contact battery provided by an embodiment of the present application;

[0050] Figure 4 is Figure 3 a cross-sectional view of the back contact battery along line IV-IV in ;

[0051] Figure 5 is another cross-sectional view of a back contact battery provided by an embodiment of the present application;

[0052] Figure 6 is another cross-sectional view of a back contact battery provided by an embodiment of the present application;

[0053] Figure 7 is a schematic diagram of the arrangement and structure of the recessed grooves in the back contact battery provided by an embodiment of the present application;

[0054] Figure 8 It is another schematic diagram of the planar structure of the back-contact battery provided by the embodiment of the present application;

[0055] Figure 9 It is another schematic diagram of the arrangement and structure of the recessed grooves in the back-contact battery provided by the embodiment of the present application;

[0056] Figure 10 It is another schematic cross-sectional view of the back-contact battery provided by the embodiment of the present application;

[0057] Figure 11 It is another schematic cross-sectional view of the back-contact battery provided by the embodiment of the present application;

[0058] Figure 12 It is another schematic cross-sectional view of the back-contact battery provided by the embodiment of the present application;

[0059] Figure 13 It is another schematic cross-sectional view of the back-contact battery provided by the embodiment of the present application;

[0060] Figure 14 It is another schematic cross-sectional view of the back-contact battery provided by the embodiment of the present application.

[0061] Description of the main component symbols:

[0062] Photovoltaic system 1000, battery module 200, back-contact battery 100, silicon substrate 10, front surface 11, back surface 12, first pole region 121, second pole region 122, first doping layer 20, recessed groove 21, second doping layer 30, leakage contact part 31, first part 311, second part 312, first dielectric layer 40, second dielectric layer 50, dielectric layer 60, back surface passivation layer 70, first electrode 80, second electrode 90, insulating dielectric layer 110, conductive thin film 120. Detailed implementation manners

[0063] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as a limitation to the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0064] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "lateral", "longitudinal", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation on the present application.

[0065] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the present application, the meaning of "a plurality" is two or more, unless otherwise specifically defined.

[0066] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected" and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection, an electrical connection or a communication connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0067] In the present application, unless otherwise clearly specified and limited, the first feature being "on" or "under" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through other features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the horizontal height of the first feature is lower than that of the second feature.

[0068] The following disclosure provides many different embodiments or examples for implementing different structures of the present application. To simplify the disclosure of the present application, components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present application. In addition, the present application may repeat reference numerals and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity and does not 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 of ordinary skill in the art may be aware of the application of other processes and / or the use scenarios of other materials.

[0069] Please refer to Figures 1 - 2 , the photovoltaic system 1000 in the embodiment of the present application may include the battery assembly 200 in the embodiment of the present application, and the battery assembly 200 in the embodiment of the present application may include a plurality of back contact batteries 100 in the embodiment of the present application.

[0070] In the embodiment of the present application, a plurality of back contact batteries 100 in the battery assembly 200 may be connected in series to form a plurality of battery strings, and each battery string may be connected in series, in parallel, or in a series-parallel combination to achieve the current converging output. For example, the connection between each battery cell may be achieved by welding a solder tape, and the connection between each battery string may be achieved by a bus bar. In some embodiments, each battery string may form a battery cell array, and then be encapsulated together with a front plate, a front encapsulant film, a back encapsulant film, and a back plate to form the battery assembly 200.

[0071] Please refer to Figure 3 and Figure 4 , the back contact battery 100 in the embodiment of the present application may include a silicon substrate 10, a plurality of first doping layers 20, and a plurality of second doping layers 30.

[0072] The silicon substrate 10 has opposite front surface 11 and back surface 12, and the back surface 12 includes first pole regions 121 and second pole regions 122 that are alternately arranged along a first direction. Both the first pole regions 121 and the second pole regions 122 extend along a second direction, and the second direction intersects with the first direction.

[0073] Specifically, as Figure 3 shown, the first pole regions 121 and the second pole regions 122 may be alternately arranged along the lateral direction of the silicon substrate 10 and both extend along the longitudinal direction. That is, the first direction may be the lateral direction of the back contact battery 100, and the second direction may be the longitudinal direction of the back contact battery 100, and the two are perpendicular to each other. Of course, in other embodiments, the first direction and the second direction may also be other directions. For example, the two may be the diagonal directions of the silicon substrate 10 respectively, and specific limitations are not made here.

[0074] The first doping layer 20 is disposed on the first pole region 121 and covers at least a partial region of the first pole region 121. Each of the first pole regions 121 is provided with the first doping layer 20, and the numbers of both are corresponding. An indentation groove 21 is formed on at least a partial first doping layer 20.

[0075] The second doping layer 30 is disposed on the second pole region 122 and covers at least a partial area of the second pole region 122. The second doping layer 30 is provided on each of the second pole regions 122, and the numbers of the two correspond to each other. At least a part of the second doping layer 30 has a leakage contact portion 31 extending onto the first doping layer 20, and the leakage contact portion 31 partially extends into the recessed groove 21. The leakage contact portion 31 is in leakage contact with the first doping layer 20 at least within the recessed groove 21.

[0076] It should be noted that in this article, when a layer structure covers a partial area or the entire area of a certain surface, it may be that a layer structure covers another layer structure, that is, the layer structure is directly stacked on the surface or a certain film layer, or there are other film layers provided between the film layer and the surface or the film layer. The coverage only serves to define the specific setting range of the film layer.

[0077] In addition, it should be noted that in this article, "leakage contact" means that there is no insulation between the leakage contact portion 31 and the first doping layer 20, but leakage conduction forms a leakage point. The two may directly contact each other to form a leakage point position, or tunneling may be achieved through other dielectric layers to achieve the function of leakage contact. For example, a dielectric layer with an electrical conduction function (such as a tunneling oxide layer, etc.) is directly provided between the leakage contact portion 31 and the first doping layer 20.

[0078] In the back contact battery 100, the battery assembly 200, and the photovoltaic system 1000 in the embodiments of the present application, a recessed groove 21 is formed on at least a part of the first doping layer 20. The second doping layer 30 has a leakage contact portion 31 extending onto the first doping layer 20. The leakage contact portion 31 partially extends into the recessed groove 21 and forms a leakage contact with the first doping layer 20 at least within the recessed groove 21. In this way, the leakage contact portion 31 of the second doping layer 30 can form a leakage contact with the first doping layer 20 within the recessed groove 21, thereby forming a leakage point position at the recessed groove 21, which can reduce the reverse breakdown voltage when the back contact battery 100 is blocked, thereby improving the anti-thermal spot performance of the back contact battery 100 and reducing the thermal spot risk of the battery assembly 200. At the same time, through the setting of the recessed groove 21, while increasing the area of the leakage contact, the accuracy of the contact area can be ensured, further optimizing the anti-thermal spot performance of the back contact battery 100 and ensuring the consistency of the anti-thermal spot performance of each back contact battery 100 during the production process.

[0079] Specifically, in the embodiments of the present application, the silicon substrate 10 may be an N-type silicon substrate 10 or a P-type silicon substrate 10, which is not specifically limited herein. 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 the first doping layer 20 is a P-type doping layer and the second doping layer 30 is a P-type doping layer, which is not specifically limited herein, as long as the polarities of the two are opposite.

[0080] In an embodiment of the present application, at least one indentation groove 21 may be formed on all of the first doping layers 20, and all of the second doping layers 30 may each have at least one leakage contact portion 31. Alternatively, indentation grooves 21 may be formed on all of the first doping layers 20, and some of the second doping layers 30 may have leakage contact portions 31. Alternatively, indentation grooves 21 may be formed on some of the first doping layers 20, and some of the second doping layers 30 may have leakage contact portions 31. There is no specific limitation here, as long as the leakage contact area does not cause a significant decrease in the efficiency of the back-contact battery 100. For example, the efficiency loss is controlled within 0.3%.

[0081] Please refer to Figure 4 , in some embodiments, a first dielectric layer 40 is provided between the first doping layer 20 and the silicon substrate 10 within the first pole region 121, and a second dielectric layer 50 is provided between the second doping layer 30 and the silicon substrate 10 within the second pole region 122.

[0082] Thus, through the provision of the first dielectric layer 40 and the second dielectric layer 50, the passivation effect can be enhanced. Specifically, both the first dielectric layer 40 and the second dielectric layer 50 can be film layers such as a tunneling oxide layer, an intrinsic amorphous silicon layer, etc.

[0083] Please continue to refer to Figure 4 , in some embodiments, a dielectric layer 60 is provided on the region within the indentation groove 21 covered by the leakage contact portion 31. The leakage contact portion 31 covers the dielectric layer 60, and the leakage contact portion 31 makes a leakage contact with the first doping layer 20 through the dielectric layer 60 within the indentation groove 21.

[0084] Thus, through the provision of the dielectric layer 60, while enhancing the passivation effect, the leakage contact portion 31 can make a leakage contact with the first doping layer 20, thereby improving the thermal hotspot resistance performance while enhancing the passivation effect. The dielectric layer 60 can be a film layer with a conductive function such as a tunneling oxide layer.

[0085] As Figure 4 shown, in some embodiments, both the first doping layer 20 and the second doping layer 30 can be doped polysilicon layers, and both the first dielectric layer 40 and the second dielectric layer 50 are tunneling oxide layers.

[0086] As Figure 4As shown, in such a case, a back passivation layer 70 is further covered on the entire back surface 12. The back passivation layer 70 is the outermost layer of the back surface 12 of the back contact battery 100. A first electrode 80 is provided above the first doping layer 20, and a second electrode 90 is provided above the second doping layer 30. The first electrode 80 can penetrate through the back passivation layer 70 and be electrically connected to the first doping layer 20, and the second electrode 90 can penetrate through the back passivation layer 70 and be electrically connected to the second doping layer 30. The first electrode 80 and the second electrode 90 can be formed by means such as paste burning through, grooving deposition, and electroplating.

[0087] It can be understood that in such an embodiment, since the leakage contact portion 31 of the second doping layer 30 extends above the first doping layer 20, the first electrode 80 needs to avoid the leakage contact portion 31. Therefore, in one embodiment, the first electrode 80 can be disposed on one side of the leakage contact portion 31, and there is no overlap between the first electrode 80 and the leakage contact portion 31 in the thickness direction. The first electrode 80 can adopt a burn-through type paste and be continuously disposed along the second direction on the portion of the first doping layer 20 not covered by the leakage contact portion 31. Of course, it can also be that an electrode groove continuously extending along the second direction is opened in the back passivation layer 70, and then the first electrode 80 is formed at the electrode groove by means of deposition, electroplating, etc. Of course, the first electrode 80 can also at least partially overlap with the leakage contact portion 31 in the thickness direction. In such a case, discontinuous spacer grooves can be first opened in the back passivation layer 70, that is, electrode grooves are opened in the regions without the leakage contact portion 31, and no electrode grooves are opened at the leakage contact portion 31, and then a discontinuous first electrode 80 is formed on the first doping layer 20 by means of deposition and electroplating.

[0088] As Figure 5 shown, in some other embodiments, the first doping layer 20 can be a doped polysilicon layer, and the second doping layer 30 can be a doped amorphous silicon layer or a doped microcrystalline silicon layer. In such a case, the first dielectric layer 40 can be a tunneling oxide layer or an intrinsic amorphous silicon layer, and the second dielectric layer 50 can be a tunneling oxide layer or an intrinsic amorphous silicon layer.

[0089] As Figure 5 shown, in such an embodiment, a conductive thin film 120, such as a TCO thin film, etc., is further covered on the entire back surface 12. The conductive thin film 120 can be the outermost layer of the back surface 12 of the back contact battery 100. An insulating groove 1201 is opened in the conductive thin film 120, so as to separate the portion of the conductive thin film 120 corresponding to the first pole region from the portion of the conductive thin film 120 corresponding to the second pole region. The first electrode 80 can be respectively disposed on the conductive thin film 120 in the first pole region, and the second electrode 90 can be respectively disposed on the conductive thin film 120 in the second pole region. In such a case, the first electrode 80 and the second electrode 90 can be formed on the conductive thin film 120 by electroplating. As Figure 4As shown, in such an embodiment, the portion of the leakage contact portion 31 located outside the recessed groove 21 is stacked on the first doped layer 20 in the thickness direction to form a stacked structure. The leakage contact portion 31 and the first doped layer 20 are electrically connected in the thickness direction, and the insulating groove 1201 can be formed at the position of the stacked structure.

[0090] In some embodiments, the leakage contact portion 31 preferably completely covers all the side wall surfaces and the bottom surface of the recessed groove 21. Of course, it may also only cover a part of the side wall surfaces and not cover the bottom surface, or only cover a part of the side wall surfaces and cover the entire bottom surface, or only cover a part of the side wall surfaces and a part of the bottom surface area, or cover all the side wall surfaces but not cover the bottom surface. Specific details are not limited here.

[0091] Please refer to Figure 4 , in some embodiments, the recessed groove 21 completely penetrates the first doped layer 20 in the thickness direction (i.e., the thickness direction of the back contact battery 100), so that the silicon substrate 10 is exposed at the recessed groove 21. The leakage contact portion 31 covers the silicon substrate 10 exposed at the recessed groove 21 and at least a part of the side wall surfaces of the recessed groove 21.

[0092] In this way, the recessed groove 21 completely penetrates the first doped layer 20, the recessed groove 21 is a through groove penetrating the first doped layer 20, the silicon substrate 10 is exposed at the recessed groove 21, the leakage contact portion 31 forms a leakage contact with the first doped layer 20 on the side wall surface of the recessed groove 21 to improve the anti-thermal spot performance. At the same time, the leakage contact portion 31 contacts the silicon substrate 10 at the bottom of the recessed groove 21. When the second doped layer 30 is the emitter doped layer of the back contact battery 100, such a setting method can further increase the emitter area of the back contact battery 100, thereby improving the efficiency of the back contact battery 100.

[0093] Specifically, in such an embodiment, the leakage contact portion 31 only forms a leakage contact with the first doped layer 20 on the side wall surface of the recessed groove 21, while the portion of the leakage contact portion 31 located at the bottom of the recessed groove 21 acts as an emitter.

[0094] Please refer to Figure 4 , in some embodiments, the recessed groove 21 completely penetrates the first doped layer 20 and a groove 125 is formed on the silicon substrate 10. The depth of the groove 125 recessed on the silicon substrate 10 is 1 μm - 6 μm.

[0095] In this way, through the setting that the recessed groove 21 completely penetrates the first doped layer 20 and the groove 125 is formed on the silicon substrate 10, it can be ensured that the leakage contact portion 31 does not form a leakage contact with the first doped layer 20 at the bottom of the recessed groove 21, but directly contacts the silicon substrate 10. When the second doped layer 30 is the emitter, the emitter area can be increased, thereby improving the efficiency.

[0096] Specifically, the recessed depth of the groove 125 in the silicon substrate 10 can be, for example, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, or any value from 1 μm to 6 μm.

[0097] Furthermore, in some embodiments, an inner expansion layer (not shown in the figure) is formed in a part of the silicon substrate 10 corresponding to the first pole region 121, and the polarity of the inner expansion layer is the same as that of the first doping layer 20; the recessed groove 21 does not penetrate through the inner expansion layer, and the leakage contact portion 31 makes a leakage contact with the surface of the inner expansion layer facing away from the silicon substrate 10.

[0098] In this way, in addition to making a leakage contact with the first doping layer 20 at the side wall surface of the recessed groove 21, the leakage contact portion 31 also makes a leakage contact with the inner expansion layer at the bottom surface of the recessed groove 21, which can increase the leakage contact area and further improve the anti-thermal spot performance.

[0099] Of course, in some embodiments, the recessed groove 21 may also penetrate through the inner expansion layer, and the leakage contact portion 31 makes a leakage contact with the exposed side surface of the inner expansion layer at the recessed groove 21. In this way, in addition to making a leakage contact with the first doping layer 20, the leakage contact portion 31 also makes a leakage contact with the side surface of the inner expansion layer, thereby improving the anti-thermal spot performance.

[0100] Please refer to Figure 6 , in some embodiments, the recessed groove 21 does not completely penetrate through the first doping layer 20 in the thickness direction of the first doping layer 20, and the leakage contact portion 31 covers at least a partial area of the bottom surface of the recessed groove 21 and at least a partial area of the side wall surface of the recessed groove 21.

[0101] In this way, the recessed groove 21 is a blind groove that does not completely penetrate through the first doping layer 20, and the leakage contact portion 31 can make a leakage contact with the first doping layer 20 both on the bottom surface and the side wall surface of the recessed groove 21.

[0102] Furthermore, in some embodiments, the recessed groove 21 does not completely penetrate through the first doping layer 20 in the thickness direction of the first doping layer, and the recessed depth of the recessed groove 21 is 20 nm - 200 nm.

[0103] In this way, by reasonably controlling the recessed depth of the recessed groove 21, the leakage contact area formed by the leakage contact portion 31 in the recessed groove 21 can be controlled within a reasonable range, avoiding excessive efficiency loss.

[0104] Specifically, in such an embodiment, the recess depth of the recessed groove 21 can be, for example, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, or any value between 20 nm and 200 nm. Specifically, there is no limitation here.

[0105] Please refer to Figure 4 and Figure 7 , in some embodiments, the first doping layer 20 has opposite first side surface 201 and second side surface 202 in the first direction, and the recessed groove 21 does not penetrate through the first side surface 201 and the second side surface 202 (as Figure 7 shown). In the first direction, there is the first doping layer 20 on both sides of the recessed groove 21.

[0106] In this way, the area of the recessed groove 21 can be controlled within a reasonable range, and excessive efficiency loss can be avoided.

[0107] Specifically, as Figure 7 shown, in such an embodiment, the first doping layer 20 has opposite third side surface 203 and fourth side surface 204 in the second direction. The recessed groove 21 can be located in the middle region of the first doping layer 20, and the recessed groove 21 only has a notch facing away from the silicon substrate 10. That is, the recessed groove 21 does not penetrate through the third side surface 203 and the fourth side surface 204. Of course, in some embodiments, the recessed groove 21 can also penetrate through at least one of the third side surface 203 and the fourth side surface 204 in the second direction.

[0108] In addition, in some embodiments, on a single first doping layer 20, the number of the recessed grooves 21 can be single or multiple. In the single case, the recessed groove 21 does not penetrate through the first side surface 201 and the second side surface 202, nor does it penetrate through the third side surface 203 and the fourth side surface 204. It can also be that it penetrates through the third side surface 203 but does not penetrate through the fourth side surface 204, or it can penetrate through both the third side surface 203 and the fourth side surface 204 at the same time (that is, the recessed groove 21 continuously extends through both ends of the first doping layer 20 in the second direction in the second direction).

[0109] In the multiple cases, in some embodiments, all the recessed grooves 21 do not penetrate through the third side surface 203 and the fourth side surface 204. In other embodiments, the recessed groove 21 closest to the third side surface 203 can also penetrate through the third side surface 203, and the recessed groove 21 closest to the fourth side surface 204 can also penetrate through the fourth side surface 204. Specifically, there is no limitation here.

[0110] Of course, please refer to Figure 8 and Figure 9, in some embodiments, the recessed groove 21 may also penetrate at least one of the first side surface 201 and the second side surface 202. For example, as Figure 8 and Figure 9 shown, in one example, the recessed groove 21 may penetrate the first side surface 201 and the second side surface 202 of the first doped layer 20 in the first direction. In another example, the recessed groove 21 may also only penetrate the first side surface 201 or only penetrate the second side surface 202 in the first direction, and specific details are not limited herein.

[0111] Specifically, as Figure 8 shown, in some embodiments, recessed grooves 21 penetrating the first side surface 201 and the second side surface 202 may be formed on all the first doped layers 20, and two adjacent second doped layers 30 are connected by a leakage contact portion 31 located in the recessed groove 21, that is, the leakage contact portion 31 traverses the first doped layer 20 in the first direction in the recessed groove 21 to connect two adjacent second doped layers 30 together.

[0112] In such an embodiment, the recessed groove 21 may penetrate the first doped layer 20 in the thickness direction. In this case, the leakage contact portion 31 makes a leakage contact with the first doped layer 20 at the side wall surface of the recessed groove 21. Of course, the recessed groove 21 may or may not penetrate the first doped layer 20 in the thickness direction. In this case, the leakage contact portion 31 makes a leakage contact with the first doped layer 20 at the side wall surface and / or the bottom surface of the recessed groove 21.

[0113] As Figure 8 shown, when the recessed groove 21 penetrates both the first side surface 201 and the second side surface 202 at the same time, the leakage contact portion 31 may completely cover the bottom surface of the recessed groove 21. In this case, the first electrode 80 may adopt the discontinuous electrode structure formed by opening discontinuous electrode grooves and through deposition and electroplating as described above.

[0114] Please refer to Figure 4 and Figure 6 , in some embodiments, the leakage contact portion 31 includes a first portion 311 located in the recessed groove 21 and a second portion 312 stacked on the surface of the first doped layer 20 facing away from the silicon substrate 10; the first portion 311 makes a leakage contact with the first doped layer 20, and there is an insulating dielectric layer 110 between the second portion 312 and the first doped layer 20.

[0115] In this way, only the first portion 311 located in the recessed groove 21 of the leakage contact portion 31 makes a leakage contact with the first doped layer 20, and the leakage contact area of the back contact battery 100 can be controlled to avoid excessive efficiency loss caused by too large a leakage contact area.

[0116] Specifically, in such an embodiment, the second part 312 covers the area outside the recessed groove 21. The second part 312 is insulated from the first doped layer 20 through the insulating dielectric layer 110. The leakage contact portion 31 forms a leakage contact with the first doped layer 20 only through the first part 311. The insulating dielectric layer 110 can be a dielectric film layer with insulating functions such as a silicon oxide film layer or a silicon nitride film layer.

[0117] Of course, it can be understood that in some embodiments, when it can be ensured that the efficiency of the back-contact battery 100 will not decrease significantly, the second part 312 can also make a leakage contact with the surface of the first doped layer 20 facing away from the silicon substrate 10, and specific limitations are not made here.

[0118] Please continue to refer to Figure 4 and Figure 6 , in some embodiments, the leakage contact portion 31 extends along the side surface of the first doped layer 20 to the surface of the first doped layer 20 facing away from the silicon substrate 10 and into the recessed groove 21. The leakage contact portion 31 also forms a leakage contact with the first doped layer 20 at the side surface of the first doped layer 20.

[0119] In this way, the leakage contact portion 31 also forms a leakage contact with the first doped layer 20 at the side surface of the first doped layer 20, which can increase the area of the leakage contact and further improve the anti-thermal-spot performance.

[0120] Specifically, as Figure 4 and Figure 6 shown, in such an embodiment, the leakage contact portion 31 of the second doped layer 30 located on one side of the first side surface 201 can extend along the first side surface 201 of the first doped layer 20 to the surface of the first doped layer 20 facing away from the silicon substrate 10, and then further extend into the recessed groove 21. The leakage contact portion 31 forms a leakage contact with the first side surface 201.

[0121] Of course, in some embodiments, the leakage contact portion 31 of the second doped layer 30 located on one side of the second side surface 202 can extend along the second side surface 202 of the first doped layer 20 to the surface of the first doped layer 20 facing away from the silicon substrate 10, and then further extend into the recessed groove 21. The leakage contact portion 31 also forms a leakage contact with the second side surface 202, and specific limitations are not made here.

[0122] Please refer to Figure 7 , in some embodiments, in the first direction, there is a first predetermined distance H1 between the recessed groove 21 and the side surface of the first doped layer 20 (that is, the one of the first side surface 201 or the second side surface 202 closest to the recessed groove 21). The size of the first predetermined distance H1 can be 10 μm - 200 μm.

[0123] In this way, it is possible to avoid the distance between the recessed groove 21 and the first side surface 201 or the second side surface 202 of the first doped layer 20 from being too large, which may cause the distance between the first electrode 80 and the first side surface 201 or the second side surface 202 to be too large, resulting in the first electrode 80 being unable to be centered, thereby improving the collection efficiency of the first electrode 80. It is also possible to avoid the distance between the recess and the first side surface 201 or the second side surface 202 of the first doped layer 20 from being too small, which may cause a significant increase in the process difficulty.

[0124] Specifically, as Figure 7 shown, in such an embodiment, the recessed groove 21 may not penetrate the first side surface 201 and the second side surface 202, and the recessed groove 21 may be disposed close to the first side surface 201. In such a case, the second doped layer 30 close to the first side surface 201 has a leakage contact portion 31, and the leakage contact portion 31 extends into the recessed groove 21. The first electrode 80 may be disposed between the recessed groove 21 and the second side surface 202, and it may be a continuous and uninterrupted structure. By setting the first predetermined distance H1 within the above reasonable range, it is possible to avoid the distance between the first electrode 80 and the first side surface 201 from being too large, resulting in a significant reduction in the collection efficiency of the first electrode 80.

[0125] In such an embodiment, the magnitude of the first predetermined distance H1 may be, for example, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, 200μm, or any value between 10μm - 200μm.

[0126] Please refer to Figure 7 , in some embodiments, in the first direction, the length L1 of the recessed groove 21 is 10μm - 80μm.

[0127] In this way, by reasonably controlling the length of the recessed groove 21 in the first direction, it is also possible to avoid the width of the recessed groove 21 from being too large, resulting in the first electrode 80 being unable to be centered and a significant reduction in the collection efficiency. That is to say, by setting the length of the recessed groove 21 in the first direction within this reasonable range, the collection efficiency of the first electrode 80 can be improved.

[0128] Specifically, in such an embodiment, in such an embodiment, the length L1 of the recessed groove 21 in the first direction may be, for example, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, or any value between 10μm - 80μm.

[0129] Please refer to Figure 7, in some embodiments, in the second direction, the length L2 of the recessed groove 21 is 10 μm - 500 μm.

[0130] Thus, by setting the length of the recessed groove 21 in the second direction within this reasonable range, it is possible to avoid excessive leakage contact area in a single recessed groove 21, which may cause excessive efficiency loss.

[0131] Specifically, in such an embodiment, the length L2 of the recessed groove 21 in the second direction can be, for example, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, 220 μm, 240 μm, 260 μm, 280 μm, 300 μm, 320 μm, 340 μm, 360 μm, 380 μm, 400 μm, 420 μm, 440 μm, 460 μm, 480 μm, 500 μm, or any value between 10 μm - 500 μm.

[0132] In some embodiments, the ratio of the length L2 of the recessed groove 21 in the second direction to the length L1 of the recessed groove 21 in the first direction is greater than or equal to 2.

[0133] Thus, in order to improve the collection efficiency, when the grooving width of the recessed groove 21 is small, by setting the length of the recessed groove 21 in the second direction to be larger, the leakage contact area can be increased, thereby ensuring the anti - hot - spot performance.

[0134] Please refer to Figure 3 、 Figure 7 and Figure 8 , in some embodiments, on a single first doped layer 20, the number of recessed grooves 21 is multiple, and the multiple recessed grooves 21 are arranged at intervals in the second direction.

[0135] Thus, by providing multiple isolated recessed grooves 21 on the first doped layer 20, it is possible to avoid excessive leakage contact area on a single first doped layer 20, which may cause excessive efficiency loss.

[0136] Please refer to Figure 7 , in some embodiments, the recessed grooves 21 on the first doped layer 20 can be arranged in a column in the second direction, which can simplify the process and improve the efficiency.

[0137] Of course, in some embodiments, in order to avoid excessive concentration of the recessed grooves 21, the recessed grooves 21 on the first doped layer 20 can be arranged in at least two columns in the second direction.

[0138] Further, in some embodiments, in the second direction, the distance H2 between two adjacent recessed grooves 21 is 1 cm - 10 cm.

[0139] In this way, it is possible to avoid the situation where the distance H2 between two adjacent recessed grooves 21 is too small and the leakage points are too concentrated, resulting in the heat generation being unable to be dissipated in time and causing a significant increase in temperature.

[0140] Specifically, in such an embodiment, the distance H2 between two adjacent recessed grooves 21 can be, for example, 1 cm, 1.5 cm, 2 cm, 2.5 cm, 3 cm, 3.5 cm, 4 cm, 4.5 cm, 5 cm, 5.5 cm, 6 cm, 6.5 cm, 7 cm, 7.5 cm, 8 cm, 8.5 cm, 9 cm, 9.5 cm, 10 cm or any value between 1 cm - 10 cm.

[0141] Further, in such an embodiment, in the second direction, the distance H2 between two adjacent recessed grooves 21 is preferably greater than or equal to 2 cm and less than 4 cm.

[0142] In this way, through the research and demonstration of the inventors of the present application, setting the spacing within this preferred range can, to the greatest extent, avoid excessive heat concentration when the number of recessed grooves 21 is set to be relatively large. That is to say, this can balance the relationship between the anti - hot - spot performance and excessive heat concentration and achieve the optimal matching effect.

[0143] Specifically, in such an embodiment, the distance H2 between two adjacent recessed grooves 21 can be preferably, for example, 2 cm, 2.2 cm, 2.4 cm, 2.6 cm, 2.8 cm, 3 cm, 3.1 cm, 3.2 cm, 3.3 cm, 3.4 cm, 3.5 cm, 3.6 cm, 3.7 cm, 3.9 cm, 3.95 cm.

[0144] In some embodiments, in the back - contact battery 100, the distribution density of the recessed grooves 21 is 0.01 pieces / cm 2 - 1.5 pieces / cm 2 . In this way, by reasonably controlling the distribution density of the recessed grooves 21, it is possible to avoid the over - concentrated distribution of leakage points.

[0145] In such an embodiment, the distribution density of the recessed grooves 21 refers to the ratio between the sum of the number of recessed grooves 21 on the back - contact battery 100 and the area of the back surface 12 of the back - contact battery 100. Specifically, the distribution density of the recessed grooves 21 can be, for example, 0.01 pieces / cm 2 , 0.05 pieces / cm 2 , 0.1 pieces / cm 2 , 0.2 pieces / cm 2 , 0.3 pieces / cm2 , 0.4 pieces / cm 2 , 0.5 pieces / cm 2 , 0.6 pieces / cm 2 , 0.7 pieces / cm 2 , 0.8 pieces / cm 2 , 0.9 pieces / cm 2 , 1 piece / cm 2 , 1.1 pieces / cm 2 , 1.2 pieces / cm 2 , 1.3 pieces / cm 2 , 1.4 pieces / cm 2 , 1.5 pieces / cm 2 or 0.01 piece / cm 2 -1.5 pieces / cm 2 Any value between them.

[0146] In some embodiments, in a single said recessed groove 21, the area of the leakage contact portion 31 in leakage contact with the first doped layer 20 is 1.2 μm 2 -1500 μm 2 .

[0147] In this way, by controlling the leakage contact area in a single recessed groove 21 within this reasonable range, the anti-thermal hotspot performance can be improved while ensuring that the efficiency loss is not too large.

[0148] Specifically, in such an embodiment, the area of the leakage contact portion 31 in leakage contact with the first doped layer 20 can be, for example, 1.2 μm 2 , 2 μm 2 , 5 μm 2 , 10 μm 2 , 50 μm 2 , 100 μm 2 , 200 μm 2 , 300 μm 2 , 350 μm 2 , 400 μm 2 , 450 μm 2 , 480 μm 2 , 500 μm 2 , 600 μm 2 , 700 μm 2 , 800 μm 2 , 900 μm 2 , 1000 μm 2 , 1100 μm 2 , 1200 μm 2 , 1300 μm 2 , 1400 μm 2 , 1500 μm2 or 1.2 μm 2 -1500 μm 2 Any value therebetween.

[0149] In some embodiments, in the back-contact cell 100, the ratio of the sum of the areas of all the leakage contact portions 31 in leakage contact with the first doped layer 20 to the back surface area of the back-contact cell 100 (i.e., the area of the back surface 12 of the silicon substrate 10) is 4.5×10 -8 -1.5×10 -5 .

[0150] Thus, setting the ratio of the area of the leakage contact to the back surface 12 within this reasonable range can prevent the area ratio of the leakage contact from being too large and seriously affecting the efficiency of the back-contact cell 100, that is, the efficiency of the back-contact cell 100 can be ensured while ensuring the anti-thermal-spot performance.

[0151] Specifically, in such an embodiment, the area ratio of the two can be, for example, 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 any other arbitrary value between 4.5×10 -8 -1.5×10 -5 There is no specific limitation herein.

[0152] Please refer to Figure 10 and Figure 12 , in some embodiments, the second pole region 122 is a groove 123 formed on the silicon substrate 10, the first doped layer 20 has a first protrusion 22 extending above the groove 123, and the leakage contact portion 31 extends along the side wall surface of the groove 123 to surround the first protrusion 22 and extends to cover the first doped layer 20, and further extends into the recessed groove 21.

[0153] Thus, the leakage contact portion 31 can also form a leakage contact with the first protrusion 22, thereby improving the anti-thermal-spot performance.

[0154] Specifically, in such an embodiment, the first doping layer 20 may be a P-type doping layer, and the second doping layer 30 may be an N-type doping layer. The P-type doping layer has a first protrusion 22. The leakage contact portion 31 may form a leakage contact only with the surface of the first protrusion 22 facing the groove 123, or may simultaneously form a leakage contact with the surface of the first protrusion 22 facing the groove 123 and the side wall surface of the first protrusion 22. Specifically, there is no limitation here.

[0155] Please refer to Figure 11 , in some embodiments, the second pole region 122 is a groove 123 formed on the silicon substrate 10. The first doping layer 20 does not completely cover the first pole region 121, so that the first pole region 121 has an exposed region 124 that is not covered by the first doping layer 20 between the first doping layer 20 and the groove 123. The leakage contact portion 31 extends to the exposed region 124 and covers the exposed region 124.

[0156] In this way, when the second doping layer 30 is the emitter of the back contact battery 100, through the setting of the exposed region 124, the area of the emitter can be increased, thereby improving the efficiency of the back contact battery 100. At the same time, due to the setting of the exposed region 124, the first doping layer 20 will not be exposed at the cross section of the groove 123, and recombination can be reduced.

[0157] Specifically, in such an embodiment, the first doping layer 20 is an N-type doping layer, and the second doping layer 30 is a P-type doping layer.

[0158] Further, in such an embodiment, in the first direction, the length L4 of the exposed region 124 is 0.3 μm - 50 μm.

[0159] In this way, setting the length of the exposed region 124 in the first direction within this reasonable range can avoid excessive recombination caused by too small a width, and can also avoid too large a length resulting in too large an area without the first doping layer 20, which may lead to too low a carrier collection efficiency and affect the overall efficiency of the battery.

[0160] Specifically, in such an embodiment, the size of the length L4 of the exposed region 124 may be, for example, 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, 15 μm, 20 μm, 25 μm, 30 μm, 40 μm, 45 μm, 50 μm, or any value between 0.3 μm and 50 μm. Specifically, there is no limitation here.

[0161] In some embodiments, the length L4 of the exposed region 124 in the first direction may preferably be 1 μm - 20 μm.

[0162] Please refer to Figure 12 In some embodiments, the recessed groove 21 completely penetrates the first doped layer 20, and a groove 125 is formed on the silicon substrate 10. The first doped layer 20 on both sides of the groove 125 has a second protruding portion 23 extending above the groove 125. The leakage contact portion 31 surrounds at least one second protruding portion 23 and extends into the recessed groove 21.

[0163] In this way, the leakage contact portion 31 can also form a leakage contact with the second protruding portion 23, thereby improving the anti-thermal spot performance.

[0164] Specifically, in such an embodiment, the first doped layer 20 may be a P-type doped layer, and the second doped layer 30 may be an N-type doped layer. The P-type doped layer has a second protruding portion 23. The leakage contact portion 31 may form a leakage contact only with the surface of the second protruding portion 23 facing the groove 123, or may also form a leakage contact with the surface of the second protruding portion 23 facing the groove 123 and the side wall surface of the second protruding portion 23. There is no specific limitation here.

[0165] Please refer to FIG. 13. In some embodiments, the recessed groove 21 completely penetrates the first doped layer 20, and a groove 125 is formed on the silicon substrate 10. The first doped layer 20 on both sides of the groove 125 has a second preset distance L5 from the edge of the groove 125.

[0166] In this way, through the setting of the second preset distance L5, the first doped layer 20 will not be exposed at the cross section of the groove 125, and recombination can be reduced.

[0167] Specifically, in such an embodiment, the first doped layer 20 is an N-type doped layer, and the second doped layer 30 is a P-type doped layer.

[0168] Further, in such an embodiment, the size of the second preset distance L5 may be 0.3 μm - 50 μm.

[0169] In this way, setting the size of the second preset distance L5 within this reasonable range can avoid excessive recombination caused by too small a second preset distance L5, and can also avoid too large a length resulting in too large an area without the first doped layer 20, which may lead to too low a carrier collection efficiency and affect the overall efficiency of the battery.

[0170] Specifically, in such an embodiment, the size of the second preset distance L5 may be, for example, 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, 15 μm, 20 μm, 25 μm, 30 μm, 40 μm, 45 μm, 50 μm or any value between 0.3 μm - 50 μm. There is no specific limitation here.

[0171] Please refer to Figure 14 , in some embodiments, the second pole region 122 is a groove 123 formed on the silicon substrate 10. At the edge of the first doped layer 20 facing the groove 123, the first doped layer 20 forms a stepped structure 24. The leakage contact portion 31 covers the side surface of the first doped layer 20 and the stepped structure 24, and the leakage contact portion 31 makes a leakage contact with the first doped layer 20 at the stepped structure 24.

[0172] Thus, through the setting of the stepped structure 24, the leakage contact portion 31 can make a leakage contact with the first doped layer 20 at the stepped structure 24, which can improve the electrode of the leakage contact, and further improve the anti-thermal spot formation of the back contact battery 100.

[0173] Specifically, as Figure 14 shown, at the edge of the first doped layer 20 facing the groove 123, the first doped layer 20 has a stepped surface. The leakage contact portion 31 covers the stepped surface and the connecting surface connecting the stepped surface and the outermost surface of the first doped layer 20 facing away from the silicon substrate 10 and makes a leakage contact with the first doped layer 20 through both of them.

[0174] In the description of this specification, the descriptions with reference to the terms "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0175] In addition, the above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A back-contact battery, characterized in that, Comprising: A silicon substrate having opposite front and back surfaces, the back surface including first pole regions and second pole regions alternately arranged in a first direction, the first pole regions and the second pole regions both extending in a second direction, the second direction intersecting the first direction; A plurality of first doping layers disposed on the first pole regions and covering at least partial regions of the first pole regions, each of the first pole regions having a first doping layer thereon, and at least partial regions of the first doping layers having recessed grooves formed therein; And A plurality of second doping layers disposed on the second pole regions and covering at least partial regions of the second pole regions, each of the second pole regions having a second doping layer thereon, at least partial regions of the second doping layers having leakage contact portions extending onto the first doping layers, and the leakage contact portions partially extending into the recessed grooves, and the leakage contact portions being in leakage contact with the first doping layers at least within the recessed grooves.

2. The back contact battery according to claim 1, characterized in that, The first doping layer has opposite first and second side surfaces in the first direction, the recessed groove does not penetrate through the first and second side surfaces, and on both sides of the recessed groove in the first direction, there are the first doping layers.

3. The back-contact battery according to claim 1, wherein The first doping layer has opposite first and second side surfaces in the first direction, the recessed groove penetrates through at least one of the first and second side surfaces.

4. The back-contact battery according to claim 1, characterized in that, The recessed groove completely penetrates through the first doping layer in the thickness direction of the first doping layer, so that the silicon substrate is exposed at the recessed groove. The leakage contact portion covers the silicon substrate exposed at the recessed groove and at least partial regions of the side wall surfaces of the recessed groove.

5. The back-contact battery according to claim 4, wherein, An inner diffusion layer is formed in a part of the silicon substrate corresponding to the first pole region, and the polarity of the inner diffusion layer is the same as that of the first doping layer; Wherein, the recessed groove does not penetrate through the inner diffusion layer, and the leakage contact portion is in leakage contact with the surface of the inner diffusion layer facing away from the silicon substrate surface; or The recessed groove penetrates through the inner diffusion layer, and the leakage contact portion is in leakage contact with the side surface of the inner diffusion layer exposed at the recessed groove.

6. The back contact battery according to claim 1, wherein, The recessed groove does not completely penetrate through the first doping layer in the thickness direction of the first doping layer, and the leakage contact portion covers at least partial regions of the bottom surface of the recessed groove and at least partial regions of the side wall surfaces of the recessed groove.

7. The back-contact battery according to claim 1, characterized in that, The leakage contact portion includes a first portion located within the recessed groove and a second portion laminated on the surface of the first doping layer facing away from the silicon substrate; the first portion is in leakage contact with the first doping layer, and there is an insulating dielectric layer between the second portion and the first doping layer.

8. The back-contact battery according to claim 1, characterized in that, The leakage contact portion includes a first portion located within the recessed groove and a second portion laminated on the surface of the first doping layer facing away from the silicon substrate; the first portion is in leakage contact with the first doping layer, and the second portion is in leakage contact with the surface of the first doping layer facing away from the silicon substrate.

9. The back-contact battery according to claim 1, wherein In the first direction, the leakage contact portion extends along the side surface of the first doped layer to the surface of the first doped layer facing away from the silicon substrate and into the recessed groove, and the leakage contact portion also forms a leakage contact with the first doped layer at the side surface of the first doped layer.

10. The back contact battery according to claim 1, characterized in that, In the first direction, there is a first predetermined distance between the recessed groove and the side surface of the first doped layer, and the size of the first predetermined distance is 10 μm - 200 μm.

11. The back-contact battery according to claim 1, wherein In the first direction, the length of the recessed groove is 10 μm - 80 μm; and / or In the second direction, the length of the recessed groove is less than 10 μm - 500 μm.

12. The back-contact battery according to claim 11, wherein, The ratio of the length of the recessed groove in the second direction to the length of the recessed groove in the first direction is greater than or equal to 2.

13. The back-contact battery according to claim 1, characterized in that, The recessed groove does not completely penetrate the first doped layer in the thickness direction of the first doped layer, and the recessed depth of the recessed groove is 20 nm - 200 nm.

14. The back-contact battery according to claim 1, wherein On a single first doped layer, the number of the recessed grooves is multiple, and the multiple recessed grooves are arranged at intervals in the second direction.

15. The back-contact battery according to claim 14, wherein In the second direction, the distance between two adjacent recessed grooves is 1 cm - 10 cm.

16. The back contact battery according to claim 15, characterized in that, In the second direction, the distance between two adjacent recessed grooves is greater than or equal to 2 cm and less than 4 cm.

17. The back-contact battery according to claim 14, wherein, The multiple recessed grooves are arranged in at least two columns in the second direction.

18. The back contact battery according to claim 1, wherein, In the back contact battery, the distribution density of the recessed grooves is 0.01 piece / cm 2 -1.5 pieces / cm 2 .

19. The back-contact battery according to claim 1, characterized in that, In a single one of the recessed grooves, the area of the leakage contact portion in leakage contact with the first doped layer is 1.2 μm 2 -1500 μm 2 .

20. The back contact battery according to claim 1, characterized in that, In the back-contact battery, the ratio of the sum of the areas of all the leakage contact portions in leakage contact with the first doped layer to the back area of the back-contact battery is 4.5×10 -8 -1.5×10 -5 .

21. The back-contact battery according to claim 1, characterized in that, The second pole region is a groove formed on the silicon substrate. The first doped layer has a first protruding portion extending above the groove. The leakage contact portion extends along the side wall surface of the groove to surround the first protruding portion and extends onto the first doped layer and into the recessed groove.

22. The back-contact battery according to claim 1, characterized in that, The second pole region is a groove formed on the silicon substrate. The first doped layer does not completely cover the first pole region, so that there is an exposed region not covered by the first doped layer between the first doped layer and the groove. The leakage contact portion extends to and covers the exposed region.

23. The back contact battery according to claim 1, characterized in that, The recessed groove completely penetrates the first doped layer in the thickness direction of the first doped layer and forms a trench on the silicon substrate. The recessed depth of the trench on the silicon substrate is 1 μm - 6 μm.

24. The back-contact battery according to claim 1, characterized in that, The recessed groove completely penetrates the first doped layer in the thickness direction of the first doped layer and forms a trench on the silicon substrate. Both the first doped layers on both sides of the trench have second protruding portions extending above the trench. The leakage contact portion surrounds at least one of the second protruding portions and extends into the recessed groove.

25. The back-contact battery according to claim 1, characterized in that, The recessed groove completely penetrates the first doped layer in the thickness direction of the first doped layer and forms a trench on the silicon substrate. In the first direction, there is a second predetermined distance between the first doped layers on both sides of the trench and the edge of the trench.

26. The back contact battery according to claim 25, characterized in that, The size of the second predetermined distance is 0.3 μm - 50 μm.

27. The back contact battery according to claim 26, characterized in that, The size of the second predetermined distance is 1 μm - 20 μm.

28. The back-contact battery according to claim 1, wherein The second pole region is a groove formed on the silicon substrate. At the edge of the first doped layer facing the groove, the first doped layer forms a stepped structure, the leakage contact portion covers the stepped structure, and the leakage contact portion makes a leakage contact with the first doped layer at the stepped structure.

29. The back contact battery according to any one of claims 1-28, characterized in that, In the first pole region, a first dielectric layer is provided between the first doped layer and the silicon substrate. In the second pole region, a second dielectric layer is provided between the second doped layer and the silicon substrate.

30. The back contact battery according to any one of claims 1-28, characterized in that, A dielectric layer is provided on the region covered by the leakage contact portion in the recessed groove. The leakage contact portion covers the dielectric layer, and the leakage contact portion makes a leakage contact with the first doped layer through the dielectric layer in the recessed groove.

31. A battery assembly, characterized in that, Including the back contact battery according to any one of claims 1-30.

32. A photovoltaic system, characterized in that, Including the battery assembly according to claim 31.

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