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, a first passivation contact structure of the back contact cell is arranged in a first region, and an insulation region is provided with a first insulation dielectric layer; the first insulating dielectric layer is provided with a body part located on the insulating region and an insulating extension part extending to the first passivation contact structure. The second passivation contact structure is provided with a first contact extension part covering the body part and a second contact extension part covering the insulation extension part, a through groove is formed in a stacked structure formed by the insulation extension part and the second contact extension part in the thickness direction, and the first conductive structure is arranged at the through groove; the second conductive structure is disposed at least on a portion of the second passivation contact structure corresponding to the second region. Therefore, through the optimal design of the first insulating dielectric layer and the second passivation contact structure, the passivation effect can be improved, the electrical isolation effect can be improved, the electric leakage risk can be reduced, and the performance of the back contact battery can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a back-contact cell, a cell assembly, and a photovoltaic system. Background Art

[0002] Currently, among solar cells, a back-contact cell is a cell in which both the emitter and base contact electrodes are placed on the back side (not the front side) of the cell. The front side of the cell is not blocked by any metal electrodes, thereby effectively increasing the short-circuit current of the cell.

[0003] In order to improve the efficiency of the back contact battery, one of the doped layers of the back contact battery can be set to a polycrystalline silicon layer, and the other doped layer can be set to an amorphous silicon layer or a microcrystalline silicon layer, thereby forming a hybrid back contact battery. That is, a hybrid back contact battery is formed by using two different passivation contact structures of opposite types.

[0004] However, in such a back-contact battery, there are processes such as etching during the deposition manufacturing process, which easily lead to the phenomenon that one of the two passivation contact structures of different passivation types covers part of the area of ​​the other. For example, it is easy for the P-type passivation contact structure to cover part of the area of ​​the N-type passivation contact structure, which can easily cause a short circuit and thus affect the performance of the back-contact battery. Utility Model Content

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

[0006] The present application is implemented as follows: the back contact battery of the embodiment of the present application includes:

[0007] A silicon substrate having a front side and a back side opposite to each other, the back side comprising a plurality of first regions and a plurality of second regions alternately arranged along a first direction, the back side further comprising an insulating region between the first regions and the second regions, the insulating region separating the first regions from the second regions, the first regions, the second regions, and the insulating spacer region all extending along a second direction, the second direction intersecting the first direction;

[0008] a first passivation contact structure stacked on the first region;

[0009] a first insulating dielectric layer, the first insulating dielectric layer comprising a main body portion stacked on the insulating region and an insulating extension portion extending and stacked to cover the entire first passivation contact structure; and

[0010] a second passivation contact structure stacked on the second region, the second passivation contact structure having a polarity opposite to that of the first passivation contact structure, the second passivation contact structure comprising a first contact extension extending along a first direction and stacked over the body portion, and a second contact extension stacked over the insulating extension portion, a through-groove being formed in the stacked structure formed by the insulating extension portion and the second contact extension portion, and a portion of the first passivation contact structure being exposed from the through-groove;

[0011] a first conductive structure, the first conductive structure being disposed at the through-groove and in conductive contact with the first passivation contact structure; and

[0012] A second conductive structure is provided at least on a portion of the second passivation contact structure corresponding to the second region, and the second conductive structure is insulated from the first passivation contact structure and the first conductive structure.

[0013] In some embodiments, the first passivation contact structure includes a first passivation layer and a first doping layer sequentially stacked in a direction facing away from the back surface, and the second passivation contact structure includes a second passivation layer and a second doping layer sequentially stacked in a direction facing away from the back surface;

[0014] The first passivation layer is a tunneling oxide layer, the first doping layer is a doped polysilicon layer, the second passivation layer is at least one of an intrinsic amorphous silicon layer or a tunneling oxide layer, and the second doping layer is at least one of a doped amorphous silicon layer and a doped microcrystalline silicon layer.

[0015] In some embodiments, a length of the insulating region in the first direction is 10 μm-600 μm.

[0016] In some embodiments, a length of the insulating region in the first direction is 10 μm-300 μm.

[0017] In some embodiments, the first region is a polished region, the insulating region is a suede region, and the thickness of the main body portion is smaller than the thickness of the insulating extension portion.

[0018] In some embodiments, the thickness of the main body portion may be 50 nm-100 nm, and the thickness of the insulating extension portion may be 60 nm-150 nm.

[0019] In some embodiments, a ratio between a thickness of the insulating extension portion and a thickness of the main body portion is 1.1-2.

[0020] In some embodiments, the first conductive structure includes a first transparent conductive film, and the first transparent conductive film is formed at least on a portion of the first passivation contact structure exposed from the through-groove.

[0021] In some embodiments, the first transparent conductive film is only disposed in the through groove, and a thickness of the first transparent conductive film is smaller than a thickness of the insulating extension portion.

[0022] In some embodiments, the first area is a polished area, the insulating area is a velvet area, the first transparent conductive film has a first conductive extension portion extending along the second contact extension portion to the first contact extension portion, and the thickness of the first conductive extension portion is less than the thickness of the portion of the first transparent conductive film corresponding to the first area.

[0023] In some embodiments, a portion of the first transparent conductive film corresponding to the first region has a thickness of 75 nm to 150 nm, and a thickness of the first conductive extension portion has a thickness of 40 nm to 80 nm.

[0024] In some embodiments, a ratio between a thickness of a portion of the first transparent conductive film corresponding to the first region and a thickness of the first conductive extension portion is 1.3-2.

[0025] In some embodiments, the first conductive structure includes a metal electrode disposed at the through-groove, and the metal electrode at least fills the through-groove to be in conductive contact with the first passivation contact structure.

[0026] In some embodiments, the second conductive structure includes a second transparent conductive film, and the second transparent conductive film is at least disposed on a portion of the second passivation contact structure corresponding to the second region and is in conductive contact with the second passivation contact structure.

[0027] In some embodiments, the second region and the insulating region are both suede regions, and the surface roughness of the insulating region is greater than the surface roughness of the second region;

[0028] The second transparent conductive film has a second conductive extension portion extending to cover at least a portion of the first contact extension portion, and a thickness of the second conductive extension portion is smaller than a thickness of a portion of the second transparent conductive film corresponding to the second region.

[0029] In some embodiments, a portion of the second transparent conductive film corresponding to the second region has a thickness of 50 nm to 90 nm, and a thickness of the second conductive extension portion has a thickness of 40 nm to 80 nm.

[0030] In some embodiments, a ratio between a thickness of a portion of the second transparent conductive film corresponding to the second region and a thickness of the second conductive extension is 1.1-2.

[0031] In some embodiments, the first area is a polishing area, and the second transparent conductive film further has a third conductive extension portion extending to cover a partial area of ​​the second contact extension portion, the third conductive extension portion is insulated from the first conductive structure, and the thickness of the third conductive extension portion is greater than the thickness of the portion of the second transparent conductive film corresponding to the second area and greater than the thickness of the second conductive extension portion.

[0032] In some embodiments, the thickness of the third conductive extension portion is 75 nm-150 nm, and the thickness of a portion of the second transparent conductive film corresponding to the second region is 50 nm-90 nm.

[0033] In some embodiments, a ratio between a thickness of the third conductive extension and a thickness of a portion of the second transparent conductive film corresponding to the second region is 1.1-1.8.

[0034] In some embodiments, the first area is a polished area, the second area is a suede area, the first conductive structure includes a first transparent conductive film, and is formed at least on a portion of the first passivation contact structure exposed from the through groove, and the thickness of the second transparent conductive film corresponding to the second area is less than the thickness of the first transparent conductive film corresponding to the first area.

[0035] In some embodiments, a portion of the first transparent conductive film corresponding to the first region has a thickness of 75 nm to 150 nm, and a portion of the second transparent conductive film corresponding to the second region has a thickness of 50 nm to 90 nm.

[0036] In some embodiments, a ratio between a thickness of a portion of the first transparent conductive film corresponding to the first region and a thickness of a portion of the second transparent conductive film corresponding to the second region is 1.1-1.8.

[0037] In some embodiments, there is a second insulating dielectric layer between the insulating extension portion and the first passivation contact structure, the through groove also penetrates the second insulating dielectric layer, the second insulating dielectric layer has a suspended section extending along the first direction and protruding from the first region, the suspended section is suspended on the insulating region, and the first insulating dielectric layer and the first contact extension portion surround the suspended section in the first direction.

[0038] In some embodiments, the thickness of the portion of the first insulating dielectric layer located on the side of the first passivation contact structure gradually decreases in a direction approaching the suspended segment; the thickness of the portion of the first contact extension located on the side of the first passivation contact structure also gradually decreases in a direction approaching the suspended segment.

[0039] In some embodiments, a portion of the first insulating dielectric layer located on the surface of the suspended segment facing the silicon substrate gradually increases in the protruding direction of the suspended segment; a portion of the first contact extension portion located on the surface of the suspended segment facing the silicon substrate also gradually increases in the protruding direction of the suspended segment.

[0040] In some embodiments, the front surface is a suede surface, the insulating region is a suede region, and the surface roughness of the insulating region is smaller than the surface roughness of the front surface.

[0041] In some embodiments, a front passivation layer is formed on the front surface, and a thickness of the front passivation layer is smaller than a thickness of the body portion.

[0042] In some embodiments, the silicon substrate further has several side surfaces connecting the front surface and the back surface, at least some of the side surfaces have a side passivation layer, and the thickness of the side passivation layer is greater than the thickness of the first insulating dielectric layer.

[0043] In some embodiments, the first insulating dielectric layer includes a first aluminum oxide film layer;

[0044] The silicon substrate also has several side surfaces connecting the front and the back, and the several side surfaces include at least one cutting surface, and the cutting surface has a second aluminum oxide film layer. The cutting surface includes a first area connected to the back and a second area farther away from the back than the first area. The ratio of oxygen and aluminum elements in the part of the second aluminum oxide film layer corresponding to the first area is greater than the ratio of oxygen and aluminum elements in the first aluminum oxide film layer.

[0045] In some embodiments, the ratio of oxygen to aluminum in the portion of the second aluminum oxide film layer corresponding to the first region is greater than the ratio of oxygen to aluminum in the portion of the second aluminum oxide film layer corresponding to the second region; and the ratio of oxygen to aluminum in the portion of the second aluminum oxide film layer corresponding to the second region is greater than the ratio of oxygen to aluminum in the first aluminum oxide film layer.

[0046] In some embodiments, a thickness of a portion of the second aluminum oxide film layer corresponding to the first region is greater than a thickness of the first aluminum oxide film layer.

[0047] In some embodiments, there is a fourth region between the first region and / or the second region closest to the edge of the silicon substrate and the edge of the silicon substrate, and a third insulating dielectric layer is provided on the fourth region, and the thickness of the third insulating dielectric layer is greater than the thickness of the first insulating dielectric layer.

[0048] In some embodiments, the first insulating dielectric layer includes a first aluminum oxide film layer, the third insulating dielectric layer includes a third aluminum oxide film layer, and the ratio of oxygen to aluminum in the third aluminum oxide film layer is greater than the ratio of oxygen to aluminum in the first aluminum oxide film layer.

[0049] The present application also provides a battery assembly, which includes several back-contact batteries as described in any one of the above items.

[0050] The present application also provides a photovoltaic system, which includes the above-mentioned battery assembly.

[0051] In the back-contact cell, cell module, and photovoltaic system of the embodiments of the present application, an insulating region is provided between a first region and a second region on the back surface. A first passivation contact structure is provided in the first region, and a first insulating dielectric layer is provided on the insulating region. The first insulating dielectric layer comprises a main body located on the insulating region and an insulating extension extending onto the first passivation contact structure and covering the entire first passivation structure. In addition to being provided on the second region, a second passivation contact structure further comprises a first contact extension covering the main body and a second contact extension covering the insulating extension. A through-groove is formed in the stacked structure formed by the insulating extension and the second contact extension in the thickness direction, with a portion of the first passivation contact structure exposed through the through-groove. A first conductive structure is provided in the through-groove and is in conductive contact with the first passivation contact structure. A second conductive structure is provided at least on the portion of the second passivation contact structure corresponding to the second region, and the second conductive structure is insulated from the first passivation contact structure and the first conductive structure. In this way, through the setting of the insulating area and the main body located on the insulating area, the first passivation contact structure and the second passivation contact structure can be isolated from each other in the first direction, thereby improving the electrical isolation effect between the two. At the same time, through the setting of the insulating extension part, the second contact extension part of the second passivation structure can be isolated from the first passivation contact structure in the thickness direction, thereby avoiding the first passivation contact structure and the second passivation contact structure from stacking and causing a short circuit, reducing the risk of leakage, and improving the performance of the back contact battery. The setting of the first contact extension section and the second contact extension section can improve the passivation effect of the first area of ​​the insulating area and improve efficiency.

[0052] 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

[0053] Figure 1 This is a module schematic diagram of a photovoltaic system provided by an embodiment of the present application;

[0054] Figure 2 Schematic diagram of a module of a battery assembly provided in an embodiment of the present application;

[0055] Figure 3 Schematic diagram of the planar structure of a back-contact battery provided in an embodiment of the present application;

[0056] Figure 4 yes Figure 3 Schematic diagram of the cross-sectional structure of the middle back contact battery along line IV-IV;

[0057] Figure 5 1 is another schematic cross-sectional structure diagram of a back-contact battery provided in an embodiment of the present application;

[0058] Figure 6 1 is another schematic cross-sectional structure diagram of a back-contact battery provided in an embodiment of the present application;

[0059] Figure 7 is another schematic cross-sectional structure diagram of a back-contact battery provided in an embodiment of the present application;

[0060] Figure 8 1 is another schematic cross-sectional view of a back-contact battery provided in an embodiment of the present application;

[0061] Figure 9 1 is another schematic cross-sectional view of a back-contact battery provided in an embodiment of the present application;

[0062] Figure 10 1 is another schematic cross-sectional view of a back-contact battery provided in an embodiment of the present application;

[0063] Figure 11 1 is another schematic cross-sectional view of a back-contact battery provided in an embodiment of the present application;

[0064] Figure 12 1 is another schematic cross-sectional view of a back-contact battery provided in an embodiment of the present application;

[0065] Figure 13 This is another schematic cross-sectional structure diagram of the back-contact battery provided in an embodiment of the present application.

[0066] Description of main component symbols:

[0067] Photovoltaic system 1000, battery assembly 200, back-contact battery 100, silicon substrate 10, front surface 11, back surface 12, first region 121, second region 122, insulating region 123, first passivation contact structure 20, first passivation layer 21, first doped layer 22, first insulating dielectric layer 30, main body 31, insulating extension 32, through-groove 301, second passivation contact structure 40, first contact extension 401, second contact extension 402, second passivation layer 41, second doped layer 42, first conductive structure 50, first transparent conductive film 51, first conductive extension 511, metal electrode 52, second conductive structure 60, second transparent conductive film 61, second conductive extension 611, third conductive extension 612, second insulating dielectric layer 70, suspended segment 71. DETAILED DESCRIPTION

[0068] In order to make the purpose, technical solutions and advantages of the present application more clear, 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, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. 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.

[0069] In the description of this application, it should be understood that the terms "length", "width", "up", "down", "horizontal", "longitudinal", etc., indicating the orientation or position relationship, are based on the orientation or position relationship 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 orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on this application.

[0070] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the described features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0071] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or mutual communication; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0072] 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.

[0073] 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.

[0074] See also Figure 1-Figure 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 multiple back-contact batteries 100 in the embodiment of the present application.

[0075] In an embodiment of the present application, multiple back-contact cells 100 in a battery assembly 200 can be connected in series to form multiple battery strings. Each battery string can be connected in series, in parallel, or in a combination of series and parallel to achieve current bus output. For example, the connection between each battery cell can be achieved by welding a welding ribbon, or the connection between each battery string can be achieved by using a bus bar. In some embodiments, each battery string can be formed into a battery cell array, which is then packaged together with a front plate, a front adhesive film, a rear adhesive film, and a back plate to form a battery assembly 200.

[0076] See also Figure 3 and Figure 4 The back contact cell 100 in the embodiment of the present application may include a silicon substrate 10, a first passivation contact structure 20, a first insulating dielectric layer 30, a second passivation contact structure 40, a first conductive structure 50 and a second conductive structure 60.

[0077] The silicon substrate 10 has a front surface 11 and a back surface 12 opposite to each other. Figure 3 As shown, the back side 12 may include a plurality of first areas 121 and a plurality of second areas 122, and the plurality of first areas 121 and the plurality of second areas 122 are alternately arranged along the first direction. The back side 12 also includes an insulating area 123 located between the first areas 121 and the second areas 122, that is, there is an insulating area 123 between adjacent first areas 121 and second areas 122, and the two are separated by the insulating area 123. The first area 121, the second area 122 and the insulating area 123 all extend along the second direction, and the second direction intersects with the first direction.

[0078] Specifically, if Figure 3 As shown, the first regions 121 and the second 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 cell 100, and the second direction may be the longitudinal direction of the back-contact cell 100, with the two being perpendicular to each other. Of course, in other embodiments, the first direction and the second direction may also be other directions, for example, both may be diagonal directions of the silicon substrate 10, and this is not limited here.

[0079] See also Figure 4 , the first passivation contact structure 20 is stacked on the first area 121, and each first area 121 is provided with a first passivation contact structure 20. Specifically, as Figure 4 As shown, in some embodiments, the first passivation contact structure 20 may include a first passivation layer 21 and a first doping layer 22, and the first passivation layer 21 and the first doping layer 22 are stacked in sequence on the first region 121 along the direction back to the back surface 12, that is, along the thickness direction of the back contact battery 100, the first passivation layer 21 and the first doping layer 22 are stacked in sequence on the first region 121, and the first passivation layer 21 and the first doping layer 22 can both completely cover the first region 121, and each first region 121 is provided with a first passivation layer 21 and a first doping layer 22.

[0080] A portion of the first insulating dielectric layer 30 is stacked on the insulating region 123 . The first insulating dielectric layer 30 includes a main portion 31 stacked on the insulating region 123 and an insulating extension portion 32 extending along the first direction and stacked to cover the entire first passivation contact structure 20 .

[0081] The second passivation contact structure 40 is stacked on the second region 122. Each second region 122 is provided with a second passivation contact structure 40. The polarity of the second passivation contact structure 40 is opposite to that of the first passivation contact structure 20. Specifically, Figure 4 As shown, the second passivation contact structure 40 may include a second passivation layer 41 and a second doping layer 42. The second passivation layer 41 and the second doping layer 42 are sequentially stacked on the second area 122 in the direction back to the back surface 12, that is, along the thickness direction of the back contact battery 100, the second passivation layer 41 and the second doping layer 42 are sequentially stacked on the second area 122, the second doping layer 42 has an opposite polarity to the first doping layer 22, the second passivation layer 41 and the second doping layer 42 both completely cover the second area 122, and each second area 122 is provided with a second passivation layer 41 and a second doping layer 42.

[0082] like Figure 4 As shown, in addition to the portion stacked on the second region 122, the second passivation contact structure 40 further includes a first contact extension 401 extending along the first direction and stacked on the main portion 31 of the first insulating dielectric layer 30, and a second contact extension 402 stacked on the insulating extension 32. Specifically, the first contact extension 401 and the second contact extension 402 each include a stacked second passivation layer 41 and a second doped layer 42. A through-groove 301 is formed in the stacked structure formed by the insulating extension 32 and the second contact extension 402 in the thickness direction, and a portion of the first passivation contact structure 20 is exposed through the through-groove 301.

[0083] The first conductive structure 50 is disposed at the through-groove 301 and is in conductive contact with the first passivation contact structure 20. The second conductive structure 60 is disposed at least on a portion of the second passivation contact structure 40 corresponding to the second region 122. The second conductive structure 60 is insulated from the first passivation contact structure 20 and the first conductive structure 50. That is, the second conductive structure 60 is not in conductive contact with the first passivation contact structure 20 and the first conductive structure 50.

[0084] In some embodiments, the second conductive structure 60 may be disposed only on the portion of the second passivation contact structure 40 corresponding to the second region 122. In other embodiments, due to the presence of the insulating extension 32, the second conductive structure 60 may also extend over the first contact extension 401 or the second contact extension 402. In other words, the present application does not limit the specific location of the second conductive structure 60; it is sufficient to ensure that the second conductive structure 60 does not directly contact the first passivation contact structure 20 and is insulated from the first conductive structure 50.

[0085] In this article, the part of a certain structure (such as a film layer, a conductive structure, etc.) corresponding to a certain area or a certain layer structure refers to the part of the structure that overlaps with the area or other layer structure in the thickness direction. For example, the part of the second passivation contact structure 40 corresponding to the second area 122 refers to the part of the second passivation contact structure 40 that covers the second area 122. If there is a similar description below, please refer to this for understanding.

[0086] In the back-contact cell 100, the cell assembly 200 and the photovoltaic system 1000 in the embodiments of the present application, an insulating region 123 is provided between the first region 121 and the second region 122 of the back side 12, a first passivation contact structure 20 is provided in the first region 121, and a first insulating dielectric layer 30 is provided on the insulating region 123, the first insulating dielectric layer 30 having a main body portion 31 located on the insulating region 123 and an insulating extension portion 32 extending onto the first passivation contact structure 20 and covering the entire first passivation structure 20. In addition to being arranged on the second zone 122, the second passivation contact structure 40 also has a first contact extension portion 401 covering the main body portion 31 and a second contact extension portion 402 covering the insulating extension portion 32. A through groove 301 is formed on the stacked structure formed by the insulating extension portion 32 and the second contact extension portion 402 in the thickness direction. Part of the first passivation contact structure 20 is exposed from the through groove 301. The first conductive structure 50 is arranged at the through groove 301 and is in conductive contact with the first passivation contact structure 20. The second conductive structure 60 is arranged at least on the portion of the second passivation contact structure 40 corresponding to the second zone 122. The second conductive structure 60 is insulated from the first passivation contact structure 20 and the first conductive structure 50. In this way, by setting the insulating area 123 and the main body 31 located on the insulating area 123, the first passivation contact structure 20 and the second passivation contact structure 40 can be isolated from each other in the first direction, thereby improving the electrical isolation effect between the two. At the same time, by setting the insulating extension part 32, the second contact extension part 402 of the second passivation structure 40 can be isolated from the first passivation contact structure 20 in the thickness direction, thereby avoiding the first passivation contact structure 20 and the second passivation contact structure 40 from stacking and causing a short circuit, reducing the risk of leakage, and improving the performance of the back contact battery 100. The setting of the first contact extension section 401 and the second contact extension section 402 can improve the passivation effect of the first area 121 of the insulating area 123 and improve efficiency.

[0087] In addition, on this basis, during the manufacturing process, after preparing the first passivation contact structure 20 and the first insulating dielectric layer 30, the second passivation structure 40 can be directly prepared as a whole on the entire back side 12 without the need to remove the first passivation contact structure 20 and the second passivation contact structure 40 on the insulating area 123 on a large scale (i.e., retaining the first passivation extension 41 and the second passivation extension 42). It is only necessary to open a through groove 301 on the stacked structure formed by the second passivation extension 42 and the insulating extension 32 to realize the extraction of current through the first conductive structure 50, which can improve the passivation effect of the first area 121 and the insulating area 123 and simplify the manufacturing process.

[0088] Furthermore, in the present application, the first doping layer 22 is fully covered by the insulating extension portion 402 and the second contact extension portion 402, so that the entire first doping layer 22 can be protected, thereby avoiding wear and scratches on the first doping layer 22 during subsequent processes, and avoiding dirt on the surface of the first doping layer 22.

[0089] That is to say, in the embodiment of the present application, by adopting the optimized design of the first insulating dielectric layer 30 and the second passivation contact structure 40, the passivation effect can be improved while the electrical isolation effect can be improved, the leakage risk can be reduced, and the performance of the back contact battery 100 can be improved, and the manufacturing process can be simplified. At the same time, it can also avoid wear and scratches on the first doping layer 22 in subsequent process steps.

[0090] Specifically, in the embodiments of the present application, the silicon substrate 10 may be an N-type silicon substrate or a P-type silicon substrate, without limitation. The first doping layer 22 may be an N-type doping layer, and the second doping layer 42 may be a P-type doping layer, or the first doping layer 22 may be a P-type doping layer, and the second doping layer 42 may be a P-type doping layer, without limitation, as long as the polarities of the two are opposite.

[0091] In an embodiment of the present application, the back contact cell 100 may be a hybrid back contact cell, the first passivation layer 21 and the first doping layer 22 constitute a first passivation contact structure 20, the second passivation layer 41 and the second doping layer 42 constitute a second passivation contact structure 40, and the types of passivation contact structures of the two are different. For example, in some embodiments, the first passivation contact structure 20 may be a tunneling passivation contact structure, and the second passivation contact structure 40 may be a heterojunction passivation contact structure.

[0092] In such a back-contact cell 100, the first doped layer 22 can be a doped polysilicon layer, and the first passivation layer 21 can be a tunneling oxide layer, such as a tunneling silicon oxide layer, forming a tunneling passivation contact structure. The second passivation layer 41 can be at least one of an intrinsic amorphous silicon layer or a tunneling oxide layer (such as a tunneling silicon oxide layer), and the second doped layer 42 can be at least one of a doped amorphous silicon layer and a doped microcrystalline silicon layer, forming a heterojunction passivation structure.

[0093] In this way, by designing the first doping layer 22 as a doped polysilicon layer and designing the second doping layer 42 as at least one of a doped amorphous silicon layer and a doped microcrystalline silicon layer, a hybrid back contact cell 100 can be formed to improve the efficiency of the back contact cell 100.

[0094] In addition, if Figure 4 As shown, when the first doped layer 22 is a doped polycrystalline silicon layer and the second doped layer 42 is at least one of a doped amorphous silicon layer and a doped microcrystalline silicon layer, the second conductive structure 60 can be in conductive contact with the first passivation contact structure 20 at the through-groove 301 while also being in contact with the second doped layer 42. Alternatively, the second conductive structure 60 can also cover the second contact extension 402, or cover both the second contact extension 402 and the first contact extension 401. It is sufficient that the second conductive structure 60 does not cover the portion of the second doped layer 42 corresponding to the second region 122 and is insulated from the first conductive structure 50. This is because the doped amorphous silicon layer and the doped microcrystalline silicon layer have poor lateral conductivity. The first contact extension 401 and the second contact extension 402 are separated by the main body 31 and the insulating extension 32, respectively. Therefore, even if the second conductive contact 60 contacts the second contact extension 402 and the second contact extension 401, the resulting leakage is minimal or even non-existent, and the efficiency of the back-contact cell 100 is substantially unaffected.

[0095] In a preferred embodiment, the first passivation layer 21 can be a tunneling oxide layer, the first doped layer 22 can be an N-type doped polycrystalline silicon layer, the second passivation layer 41 can be an intrinsic amorphous silicon layer, and the second doped layer 42 can be a P-type doped amorphous silicon layer or a P-type doped microcrystalline silicon layer. In this manner, the first passivation layer 21 and the first doped layer 22 are configured as a tunneling passivation contact structure, and the second passivation layer 41 and the first doped layer 22 are configured as a heterojunction passivation contact structure. Compared to a case where the second passivation layer 41 is a tunneling passivation layer and the second doped half layer is a doped polycrystalline silicon layer or a doped microcrystalline silicon layer, this can reduce the carrier recombination rate and improve the conversion efficiency of the back-contact cell 100. Furthermore, by covering the insulating region 123 and the first region 121 with a doped amorphous silicon layer and / or a doped microcrystalline silicon layer, the passivation effect of the first region 121 and the insulating region 123 can be further enhanced.

[0096] In the embodiments of the present application, the first insulating dielectric layer 30 may be made of an insulating material and may have a single-layer or multi-layer structure, without limitation. In some embodiments, the first insulating dielectric layer 30 may be at least one of an aluminum oxide film layer, a silicon nitride film layer, a silicon oxide film layer, a silicon oxynitride film layer, a silicon carbide film layer, and a phosphorus oxide film layer, or a combination thereof.

[0097] In some embodiments, the first insulating dielectric layer 30 may be a single-layer structure composed of an aluminum oxide film layer or a silicon nitride film layer. Of course, in some embodiments, the first insulating dielectric layer 30 may also be a double-layer structure composed of an aluminum oxide film layer and a silicon nitride film layer. For example, in some embodiments, the aluminum oxide film layer and the silicon nitride film layer may be stacked in sequence in a direction away from the back surface 12. In other embodiments, the silicon nitride film layer and the aluminum oxide film layer may be stacked in sequence in a direction away from the back surface 12.

[0098] In some embodiments, the length of the insulating region 123 in the first direction may be 10 μm-600 μm.

[0099] In this way, setting the length of the insulating region 123 in the first direction within this reasonable range can effectively avoid the insulating region 123 having a length in the first direction that is too small, resulting in poor electrical isolation effect. At the same time, it can also avoid the insulating region 123 having a length in the first direction that is too large, resulting in an area on the entire back side 12 where the first passivation contact structure 20 and the second passivation contact structure 40 are not set that is too large, thereby affecting the efficiency of the back contact battery 100.

[0100] In addition, the setting of the insulating region 123 can improve the bifaciality of the back-contact battery 100. By setting the length of the insulating region 123 within this reasonable range, the relationship between the efficiency and the bifaciality of the back-contact battery 100 can be balanced, and the relationship between the efficiency and the bifaciality can be optimized, thereby improving the bifaciality of the back-contact battery 100 while ensuring the efficiency of the back-contact battery 100.

[0101] That is to say, in the embodiment of the present application, through such a setting, the relationship between the efficiency and bifaciality of the back contact battery 100 can be balanced while the electrical isolation effect is improved to reduce the risk of leakage. While ensuring the electrical isolation effect to reduce the risk of leakage, the efficiency and bifaciality of the back contact battery 100 can achieve a better matching effect.

[0102] Specifically, in such an embodiment, the length of the insulating region 123 in the first direction may be, for example, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 150μm, 200μm, 250μm, 300μm, 350μm, 400μm, 450μm, 500μm, 550μm, 600μm or any value between 10μm-600μm.

[0103] Furthermore, in such an embodiment, after repeated research and demonstration by the inventors, it was found that in order to achieve the optimal matching effect between the efficiency and bifaciality of the back-contact battery 100, the length D1 of the insulating region 123 in the first direction may preferably be 10μm-300μm, for example, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 150μm, 200μm, 250μm, 300μm.

[0104] See also Figure 5 In some embodiments, the first region 121 is a polished region (i.e., the surface of the first region 121 is a polished surface), the insulating region 123 is a velvet region (i.e., the surface of the insulating region 123 is velvet), and the thickness of the main body 31 is less than the thickness of the insulating extension portion 32.

[0105] In this way, by setting the thickness of the main body 31 located on the insulating region 123 in the first insulating dielectric layer 30 to be smaller, the parasitic absorption of light by the first insulating dielectric layer 30 in the insulating region 123 can be reduced, thereby further improving the double-sidedness. By setting the thickness of the insulating extension portion 32 to be larger, the hydrogen passivation effect of the first region 121 can be improved.

[0106] Furthermore, in some embodiments, the thickness of the main body portion 31 may be 50 nm-100 nm, and the thickness of the insulating extension portion 32 may be 60 nm-150 nm.

[0107] Thus, by setting the thicknesses of the two regions within the above ranges, the passivation effects of the first region 121 and the insulating region 123 can be effectively improved while the bifaciality of the back contact cell 100 can be effectively improved.

[0108] Specifically, in such an embodiment, the thickness of the main body 31 may be, for example, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, or any value between 50 nm and 100 nm, without limitation. The thickness of the insulating extension 32 may be, for example, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, 105 nm, 110 nm, 115 nm, 120 nm, 125 nm, 130 nm, 135 nm, 140 nm, 145 nm, 150 nm, or any value between 60 nm and 150 nm, without limitation.

[0109] Furthermore, in some embodiments, the ratio of the thickness of the insulating extension portion 32 to the thickness of the main body portion 31 may be 1.1-2.

[0110] Thus, setting the thickness ratio between the two within this reasonable range can improve the passivation effect and double-sidedness while avoiding excessive costs.

[0111] Specifically, in such an embodiment, the ratio between the two may be, for example, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, 2 or any value between 1.1 and 2, and is not limited thereto.

[0112] See also Figure 4-Figure 6 In some embodiments, the first conductive structure 50 may include a first transparent conductive film 51 , and the first transparent conductive film 51 is formed at least on a portion of the first passivation contact structure 20 exposed from the through-groove 301 .

[0113] In this way, by configuring the first conductive structure 50 as a first transparent conductive film 51 that can transmit light, the current of the back contact cell 100 can be extracted while the bifaciality of the back contact cell can be improved.

[0114] Specifically, in the embodiment of the present application, the first transparent conductive film 51 may be a transparent conductive film layer such as a TCO film layer. It should be noted that in such an embodiment, electrodes may also be provided on the first transparent conductive film 51 to facilitate welding in the subsequent process of forming components. For example, electrodes such as copper electrodes may be formed on a portion of the first transparent conductive film 51 by electroplating. Of course, in some embodiments, there is no need to provide additional electrodes on the first transparent conductive film 51, and welding may be performed directly through the first transparent conductive film 51.

[0115] like Figure 4 and Figure 5 As shown, in such an embodiment, the second doped layer 42 may be at least one of a doped amorphous silicon layer and a doped microcrystalline silicon layer. Since the lateral conductivity of the doped amorphous silicon layer and the doped microcrystalline silicon layer is poor and due to the existence of the insulating extension portion 402, the first transparent conductive film 51 can not only be set at the through groove 301, but also cover the second contact extension portion 402.

[0116] See also Figure 6 In such an embodiment, in some embodiments, the first region 121 may be a polished region, the insulating region 123 may be a suede region, and the first transparent conductive film 51 has a first conductive extension portion 511 extending along the second contact extension portion 402 to the first contact extension portion 401, and the thickness of the first conductive extension portion 511 is less than the thickness of the portion of the first transparent conductive film 51 corresponding to the first region 121.

[0117] Thus, on the one hand, configuring the insulating region 123 as a suede region can reduce the reflectivity of backlight, thereby further improving the bifaciality. On the other hand, configuring the first conductive extension 511 can enhance the passivation effect at the insulating region 123, and configuring the first conductive extension 511 in the suede region to have a smaller thickness can reduce parasitic absorption of backlight at the insulating region 123, further improving the bifaciality.

[0118] In some embodiments, the thickness of the portion of the first transparent conductive film 51 corresponding to the first region 121 may be 75 nm-150 nm, and the thickness of the first conductive extension portion 511 may be 40 nm-80 nm.

[0119] Thus, on the one hand, by setting the thickness of the first conductive extension 511 within a reasonable range of 40 nm to 80 nm, it is possible to avoid the first conductive extension 511 being too thin, which would result in poor passivation effect on the insulating region 123, while also avoiding excessive parasitic absorption and increased costs due to excessive thickness. On the other hand, by setting the thickness of the portion of the first transparent conductive film 51 corresponding to the first region 121 within a reasonable range of 75 nm to 150 nm, it is possible to avoid the portion of the first transparent conductive film 51 corresponding to the first region 121 being too thin, which would result in excessive manufacturing difficulty, and also avoid the portion of the first transparent conductive film 51 corresponding to the first region 121 being too thin, which would result in poor passivation effect on the first doped layer 22, while also avoiding excessive parasitic absorption and increased costs due to excessive thickness.

[0120] Specifically, in such an embodiment, the thickness of the first conductive extension portion 511 may be, for example, 40nm, 42nm, 44nm, 46nm, 48nm, 50nm, 52nm, 54nm, 56nm, 58nm, 60nm, 62nm, 64nm, 66nm, 68nm, 70nm, 72nm, 74nm, 76nm, 78nm, 80nm or any value between 40nm-80nm, and there is no specific limitation here.

[0121] The thickness of the portion of the first transparent conductive film 51 corresponding to the first area 121 can be, for example, 75nm, 80nm, 85nm, 90nm, 95nm, 100nm, 105nm, 110nm, 115nm, 120nm, 125nm, 130nm, 135nm, 140nm, 145nm, 150nm or any value between 75nm and 150nm, and is not limited here.

[0122] In some embodiments, a ratio between the thickness of a portion of the first transparent conductive film 51 corresponding to the first region 121 and the thickness of the first conductive extension 511 is 1.3-2.

[0123] Thus, by setting the ratio between the thickness of the portion of the first transparent conductive film 51 corresponding to the first region 121 and the thickness of the first conductive extension 511 within this reasonable range, the parasitic absorption and passivation effects on the back surface can be better matched.

[0124] Specifically, in such an embodiment, the ratio between the two may be, for example, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, 2 or any value between 1.3 and 2, and is not limited here.

[0125] See also Figure 7 In some embodiments, the first transparent conductive film 51 may be disposed only in the through groove 301 , and the thickness of the first transparent conductive film 51 may be smaller than the thickness of the insulating extension portion 32 .

[0126] Thus, by placing the first transparent conductive film 51 only within the through-groove 301 and setting the thickness of the first transparent conductive film 51 to be less than the thickness of the insulating extension 32, the first transparent conductive film 51 can be electrically isolated from the second contact extension 402, further reducing the risk of leakage. Furthermore, the first transparent conductive film 51 can cover the entire area of ​​the first passivation contact structure 20 exposed from the through-groove 301, thereby improving the passivation effect of the back-contact battery 100.

[0127] Specifically, in such an embodiment, the second doping layer 42 may be a doping layer with good lateral conductivity, or a doped amorphous silicon layer and / or a doped microcrystalline silicon layer with poor lateral conductivity.

[0128] See also Figure 8 In some embodiments, the first conductive structure 50 may not adopt the first transparent conductive film 51 described above, but may include a metal electrode 52 arranged in the through-groove 301, and the metal electrode 52 at least fills the through-groove 301 to be in conductive contact with the first passivation contact structure 20.

[0129] In this way, directly providing the metal electrodes 52 can facilitate welding in the subsequent component formation process.

[0130] Specifically, in such an embodiment, the second doped layer 42 is at least one of a doped amorphous silicon layer and a doped microcrystalline silicon layer, and the metal electrode 52 can be, for example, a silver electrode, a silver-clad copper electrode, or other metal electrode, which is not specifically limited here.

[0131] Of course, see Figure 9 In some embodiments, when the second doped layer 42 is a doped layer with good lateral conductivity or in order to further reduce the risk of leakage, the metal electrode 52 may not completely fill the through-groove 301 but may be spaced from the second contact extension section 42 to achieve insulation between the two.

[0132] See also Figure 4-Figure 6 In some embodiments, the second conductive structure 60 may include a second transparent conductive film 61 , which is disposed at least on a portion of the second passivation contact structure 40 corresponding to the second region 122 and in conductive contact with the second passivation contact structure 40 .

[0133] In this way, by configuring the second conductive structure 60 as a second transparent conductive film 61 that can transmit light, the current of the back contact cell 100 can be extracted while the bifaciality of the back contact cell can be improved.

[0134] See also Figure 4-Figure 6 In some embodiments, the insulating region 123 and the second region 122 are both velvet regions (i.e., the surfaces of the insulating region 123 and the second region 122 are not velvet), the surface roughness of the second region 122 is less than the surface roughness of the insulating region 123, and the second transparent conductive film 61 has a second conductive extension portion 611 that extends at least to the first contact extension portion 401, and the thickness of the second conductive extension portion 611 is less than the thickness of the portion of the second transparent conductive film 61 corresponding to the second region 122.

[0135] In this way, on the one hand, the setting of the second conductive extension portion 611 can further enhance the passivation effect of the insulating area 123. On the other hand, setting both the insulating area 123 and the second area 122 as suede areas can reduce the reflectivity of the back light and improve the double-sidedness. Setting the thickness of the second conductive extension portion 611 located on the insulating area 123 in the second transparent conductive film 61 to be smaller than the thickness of the portion of the second transparent conductive film 61 corresponding to the second area 122 can further reduce the parasitic absorption of light in the insulating area 123, further improve the double-sidedness, and also enhance the passivation effect of the second area 122.

[0136] Furthermore, in such an embodiment, the thickness of the second conductive extension portion 611 may be 40 nm-80 nm, and the thickness of the portion of the second transparent conductive film 61 corresponding to the second region 122 may be 50 nm-90 nm.

[0137] In this way, by setting the thicknesses of the two regions within the above ranges, the bifaciality of the back contact cell 100 can be effectively improved while ensuring the passivation effect of the second region 122 and the insulating region 123 .

[0138] Specifically, in such an embodiment, the thickness of the second conductive extension 611 may be, for example, 40 nm, 42 nm, 44 nm, 46 nm, 48 nm, 50 nm, 52 nm, 54 nm, 56 nm, 58 nm, 60 nm, 62 nm, 64 nm, 66 nm, 68 nm, 70 nm, 72 nm, 74 nm, 76 nm, 78 nm, 80 nm, or any value between 40 nm and 80 nm, without limitation thereto. The thickness of the portion of the second transparent conductive film 61 corresponding to the second region 122 may be, for example, 50 nm, 52 nm, 54 nm, 56 nm, 58 nm, 60 nm, 62 nm, 64 nm, 66 nm, 68 nm, 70 nm, 72 nm, 74 nm, 76 nm, 78 nm, 80 nm, 82 nm, 84 nm, 86 nm, 88 nm, 90 nm, or any value between 50 nm and 90 nm, without limitation thereto.

[0139] Furthermore, in some embodiments, the ratio between the thickness of the portion of the second transparent conductive film 61 corresponding to the second region 122 and the thickness of the second conductive extension 611 is 1.1-2.

[0140] Thus, by setting the ratio between the thickness of the portion of the second transparent conductive film 61 corresponding to the second region 122 and the thickness of the second conductive extension 611 within this reasonable range, the parasitic absorption and passivation effects on the back surface can be better matched.

[0141] Specifically, in such an embodiment, the ratio between the two may be, for example, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, or any value between 1.1-2, and is not limited thereto.

[0142] See also Figure 10 In some embodiments, the first region 121 is a polished region (i.e., the surface of the first region 121 is a polished surface), and the second transparent conductive film 61 further has a third conductive extension portion 612 extending to cover a partial area of ​​the second contact extension portion 402. The third conductive extension portion 612 is insulated from the first conductive structure 50. The thickness of the third conductive extension portion 612 is greater than the thickness of the portion of the second transparent conductive film 61 corresponding to the second region 122, and greater than the thickness of the second conductive extension portion 611.

[0143] In this way, by setting the second conductive extension portion 611 and the third conductive extension portion 612, the passivation effect of the insulating region 123 and the first region 121 can be improved. At the same time, when the first doping layer 22 is a doped polycrystalline silicon layer and the second doping layer 42 is a doped amorphous silicon layer or a doped microcrystalline silicon layer, the thickness of the third conductive extension portion 612 located on the first region 121 is set to be thicker, which can further improve the passivation effect at the first region 121, and the transparent conductive film on the velvet region (the second region 122 and the insulating region 123) is set to be thinner, which can reduce the parasitic absorption of the back light while ensuring the passivation effect, thereby improving the double-sidedness.

[0144] Furthermore, in such an embodiment, the thickness of the third conductive extension portion 612 may be 75 nm-150 nm, and the thickness of the portion of the second transparent conductive film 61 corresponding to the second region 122 may be 50 nm-90 nm.

[0145] In this way, by setting the thicknesses of the two regions within the above ranges, the bifaciality of the back contact cell 100 can be effectively improved while ensuring the passivation effect of the second region 122 and improving the passivation effect of the first region 121 .

[0146] Specifically, in such an embodiment, the thickness of the portion of the second transparent conductive film 61 corresponding to the second region 122 may be, for example, 50nm, 52nm, 54nm, 56nm, 58nm, 60nm, 62nm, 64nm, 66nm, 68nm, 70nm, 72nm, 74nm, 76nm, 78nm, 80nm, 82nm, 84nm, 86nm, 88nm, 90nm or any value between 50nm-90nm, and is not limited here.

[0147] The thickness of the third conductive extension portion 612 may be, for example, 75nm, 80nm, 85nm, 90nm, 95nm, 100nm, 105nm, 110nm, 115nm, 120nm, 125nm, 130nm, 135nm, 140nm, 145nm, 150nm or any value between 75nm-150nm, and is not limited here.

[0148] Furthermore, in some embodiments, the ratio of the thickness of the third conductive extension 612 to the thickness of the second transparent conductive film 61 and the portion corresponding to the second region 122 is 1.1-1.8.

[0149] Thus, by setting the ratio between the thickness of the third conductive extension portion 612 and the thickness of the portion of the second transparent conductive film 61 corresponding to the second region 122 within this reasonable range, the parasitic absorption and passivation effects on the back surface can be better matched.

[0150] Specifically, in such an embodiment, the ratio between the two may be, for example, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8 or any value between 1.1-1.8, and is not limited here.

[0151] See also Figure 4-Figure 5 as well as Figure 10 In some embodiments, the first region 121 is a polished region and the second region 122 is a suede region. In the case where the first conductive structure 50 includes a first transparent conductive film 51 and the first transparent conductive film 51 is formed at least on a portion of the first passivation contact structure 20 exposed from the through groove 301, that is, the first conductive structure 50 is the first transparent conductive film 51 and the second conductive structure 60 is the second transparent conductive film 61, in such a case, the thickness of the portion of the second transparent conductive film 61 corresponding to the second region 122 is less than the thickness of the portion of the first transparent conductive film 51 corresponding to the first region 121.

[0152] In this way, on the one hand, setting the second area 122 of the back side 12 as a suede area can further reduce the reflectivity of the back light, thereby further improving the bifaciality. Setting the first area 121 as a polishing area can possibly improve the passivation effect of the first area 121 when the first doping layer 22 is a doped polysilicon layer. On the other hand, setting the thickness of the second transparent conductive film 61 located on the suede area to be smaller than the thickness of the first transparent conductive film 51 located on the polishing area, when the back light enters, the parasitic absorption at the suede area can be reduced, thereby improving the bifaciality of the back contact battery 100.

[0153] In some embodiments, the thickness of the first transparent conductive film 51 corresponding to the first region 121 may be 75 nm-150 nm, and the thickness of the second transparent conductive film 61 corresponding to the second region 122 may be 50 nm-90 nm.

[0154] Thus, on the one hand, by setting the thickness of the portion of the second transparent conductive film 61 corresponding to the second region 122 within this reasonable range, it is possible to avoid the portion of the second transparent conductive film 61 corresponding to the second region 122 being too thin, which would result in excessive difficulty in manufacturing, and to avoid the portion of the second transparent conductive film 61 corresponding to the second region 122 being too thin, which would result in poor passivation effect on the second doped layer 42 due to such a thin thickness, while also avoiding the portion of the second transparent conductive film 61 corresponding to the second region 121 being too thin, which would result in excessive difficulty in manufacturing, and to avoid the portion of the first transparent conductive film 51 corresponding to the first region 121 being too thin, which would result in poor passivation effect on the first doped layer 30 due to such a thin thickness, while also avoiding the portion of the first transparent conductive film 51 corresponding to the first ...

[0155] In other words, setting the thickness of the two within the above reasonable range can reduce the process difficulty, ensure the passivation effect, control the cost, reduce the parasitic absorption on the back side and improve the double-sidedness.

[0156] Specifically, in such an embodiment, the thickness of the portion of the second transparent conductive film 61 corresponding to the second area 122 may be, for example, 50nm, 52nm, 54nm, 56nm, 58nm, 60nm, 62nm, 64nm, 66nm, 68nm, 70nm, 72nm, 74nm, 76nm, 78nm, 80nm, 82nm, 84nm, 86nm, 88nm, 90nm or any value between 50nm-90nm, and is not limited here.

[0157] The thickness of the portion of the first transparent conductive film 51 corresponding to the first area 121 can be, for example, 75nm, 80nm, 85nm, 90nm, 95nm, 100nm, 105nm, 110nm, 115nm, 120nm, 125nm, 130nm, 135nm, 140nm, 145nm, 150nm or any value between 75nm and 150nm, and is not limited here.

[0158] In some embodiments, a ratio between the thickness of the portion of the first transparent conductive film 51 corresponding to the first region 121 and the thickness of the portion of the second transparent conductive film 61 corresponding to the second region 122 is 1.1-1.8.

[0159] Thus, by setting the ratio between the thickness of the first transparent conductive film 51 corresponding to the first area 121 and the thickness of the second transparent conductive film 61 corresponding to the second area 122 within this reasonable range, the parasitic absorption and passivation effects on the back side can be better matched.

[0160] Specifically, in such an embodiment, the ratio between the two may be, for example, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8 or any value between 1.1-1.8, and is not limited here.

[0161] In addition, in the embodiment of the present application, when the second transparent conductive film 61 includes the second conductive extension portion 611 and the third conductive extension portion 612, and the first conductive structure 50 includes the first transparent conductive film 51, Figure 4 and Figure 10 As mentioned above, the first transparent conductive film 51 may be located only on the first region 121. In this case, the thickness of the third conductive extension 612 may be the same as that of the first transparent conductive film 51. Figure 6 As shown and described above, if the first transparent conductive film 51 has the first conductive extension 511 , the second transparent conductive film 61 does not have the third conductive extension 612 . In this case, the thickness of the second conductive extension 611 can be the same as the thickness of the first conductive extension 511 to reduce parasitic absorption at the insulating region 123 .

[0162] See also Figure 11 In some embodiments, a second insulating dielectric layer 70 is provided between the insulating extension portion 32 and the first passivation contact structure 20. The through groove 301 also penetrates the second insulating dielectric layer 70. The second insulating dielectric layer 70 has a suspended segment 71 extending along the first direction and protruding from the first region 121. The suspended segment 71 is suspended above the insulating region 123. The first insulating dielectric layer 30 and the first contact extension portion 401 surround the suspended segment 71 in the first direction.

[0163] In this way, by further disposing the second insulating dielectric layer 70 between the first insulating dielectric layer 30 and the first doped layer 22 , and the second insulating dielectric layer 70 having the suspended section 71 , the electrical isolation effect of the back contact battery 100 can be further improved.

[0164] At the same time, in the thickness direction of the back contact battery 100, a deposition space is formed between the suspended section 71 and the insulating area 123, so that in the process of subsequent deposition of the first insulating dielectric layer 30, the setting of such a deposition space can suppress the sufficient exchange of plasma in the area and plasma components outside the area, thereby realizing the localized distribution of the mobile hydrogen content in the first insulating dielectric layer 30, so that the mobile hydrogen content of the first insulating dielectric layer 30 in the deposition area is lower, and the mobile hydrogen content of the first insulating dielectric layer 30 in the remaining areas is higher, so as to achieve the best passivation and anti-attenuation effects.

[0165] Specifically, the second insulating dielectric layer 70 may be one or more of silicon oxide, silicon nitride and silicon oxynitride. The second insulating dielectric layer 70 may contain the same doping elements as the doping elements in the first doping layer 22. For example, when the first doping layer 22 is N-type doped polysilicon, the second insulating dielectric layer 70 may be a PSG film layer.

[0166] For further information, please refer to Figure 11 In some embodiments, the thickness of the first insulating dielectric layer 30 located on the side surfaces of the first passivation contact structure 20 (i.e., the side surfaces of the first passivation layer 21 and the first doped layer 22) gradually decreases in a direction approaching the suspended segment 71 (i.e., the direction away from the silicon substrate 10). The thickness of the first contact extension 401 (i.e., the second passivation layer 41 and the second doped layer 42) located on the side surfaces of the first passivation contact structure 20 (i.e., the side surfaces of the first passivation layer 21 and the first doped layer 22) gradually decreases in a direction approaching the suspended segment 71.

[0167] In this way, by designing such a thickness change scheme, on the one hand, the conductive performance of the parts of the first insulating dielectric layer 30, the second passivation layer 41 and the second doping layer 42 in contact with the first passivation layer 21 and the first doping layer 22 can be made poor, thereby reducing the risk of short circuit leakage. On the other hand, the structural stress of each film layer can be reduced, thereby improving the stability of the battery structure.

[0168] Please continue reading Figure 11 In some embodiments, the portion of the first insulating dielectric layer 30 located on the surface of the suspended section 71 facing the silicon substrate 10 gradually increases in the protruding direction of the suspended section 71, and the thickness of the portion of the first contact extension 401 (i.e., the second passivation layer 41 and the second doping layer 42) located on the surface of the suspended section 71 facing the silicon substrate 10 gradually increases in the protruding direction of the suspended section 70.

[0169] In this way, the electrical isolation effect of the back contact can be further improved, and the risk of short circuit and leakage can be further reduced. At the same time, by designing such a thickness change scheme, the structural stress of the film layer can be reduced and the stability of the battery structure can be improved.

[0170] Specifically, in such an embodiment, due to the shielding effect of the suspended segment 71, during the process of depositing the first insulating dielectric layer 30, the thickness of the first insulating dielectric layer 30 at the shielding position can undergo the above-mentioned change. This change can bring about a better electrical isolation effect, reduce the risk of leakage short circuit, and also improve the stability of the battery structure.

[0171] In some embodiments, the front surface 11 may be a suede surface, and the insulating region 123 may be a suede surface. The surface roughness of the insulating region 123 is smaller than the surface roughness of the front surface 11 .

[0172] In this way, by setting both the insulating area 123 and the front side 11 to be velvet and the surface roughness of the insulating area 123 is less than the surface roughness of the front side 11, the reflectivity of the front light can be reduced to improve the efficiency of the back contact battery 100 while improving the bifaciality of the back contact battery 100.

[0173] See also Figure 12 In some embodiments, a front passivation layer 80 may be formed on the front surface 11 , and the thickness of the front passivation layer 80 is less than the thickness of a portion of the first insulating dielectric layer 30 corresponding to the insulating region 123 .

[0174] In this way, by setting the thickness of the front passivation layer 80 on the light-receiving side to be smaller, the parasitic absorption of the front light can be reduced, and the efficiency of the back-contact cell 100 can be further improved.

[0175] Specifically, in such an embodiment, the front passivation layer 80 may be an anti-reflection passivation layer, which may be at least one of a silicon nitride film layer, an aluminum oxide film layer, a silicon oxide film layer, and a silicon oxynitride film layer. The front passivation layer 80 may be a single-layer film structure or a double-layer or multi-layer film structure, and there is no specific limitation here.

[0176] Please continue reading Figure 12 In some embodiments, the silicon substrate 10 further has a plurality of side surfaces 13 connecting the front surface 11 and the back surface 12 , and at least some of the side surfaces 13 have a side passivation layer 90 , and the thickness of the side passivation layer 90 is greater than the thickness of the first insulating dielectric layer 30 .

[0177] Thus, by providing a side passivation layer 90 on the side surface 13 of the silicon substrate 10 and the side passivation layer 90 being thicker than the first insulating dielectric layer 30 , the side surface 13 of the silicon substrate 10 can be efficiently passivated, reducing edge recombination, thereby further improving conversion efficiency.

[0178] See also Figure 12In some embodiments, the first insulating dielectric layer 30 may include a first aluminum oxide film layer. Specifically, the first insulating dielectric layer 30 may include at least one aluminum oxide film layer, which may be a single aluminum oxide film layer or may include other film layers in addition to the aluminum oxide film layer. The specific embodiment is not limited here. The side surfaces 13 of the silicon substrate 10 include at least one cut surface 131. In other words, the back-contact cell 100 is a sliced ​​cell. Among the side surfaces 13 of the silicon substrate 10, at least one side surface 13 is a cut surface. For example, when the back-contact cell 100 is generally rectangular, at least one of the two side surfaces 13 of the silicon substrate 10 in the first direction is a cut surface 131.

[0179] The cut surface 131 has a second aluminum oxide film layer 91 thereon. That is, on the cut surface 131 , the side passivation layer 90 mentioned above includes the second aluminum oxide film layer 91 .

[0180] In this case, the cutting surface 131 includes a first region 1311 connected to the back side 12 and a second region 1312 farther away from the back side 12 than the first region 1311, and the ratio of oxygen elements to aluminum elements in the portion of the second aluminum oxide film layer 91 corresponding to the first region 1311 is greater than the ratio of oxygen elements to aluminum elements in the first aluminum oxide film layer.

[0181] Specifically, the first region 1311 is the cutting area when the cell is cut and is directly affected by external cutting forces. During the cutting process, the first region 1311 of the cut surface 131, close to the back surface 12, is prone to producing more defects and larger surface recombination. Therefore, setting a higher ratio of oxygen to aluminum in the portion of the second aluminum oxide film 91 corresponding to the first region 1311 can achieve efficient passivation in this region, reduce recombination, and thus improve the efficiency of the back-contact cell 100.

[0182] Further, in such an embodiment, the ratio of oxygen to aluminum in the portion of the second aluminum oxide film layer 91 corresponding to the first region 1311 is greater than the ratio of oxygen to aluminum in the portion of the second aluminum oxide film layer 91 corresponding to the second region 1312; and, the ratio of oxygen to aluminum in the portion of the second aluminum oxide film layer 91 corresponding to the second region 1312 is greater than the ratio of oxygen to aluminum in the first aluminum oxide film layer.

[0183] Specifically, the second region 1312 is generally not subject to external cutting forces or is subject to relatively small cutting forces during cutting, making it less likely to produce large defects. However, if the oxygen content in this region is too high, it is likely to introduce numerous defects. Therefore, by setting the ratio of oxygen to aluminum in the portion of the second aluminum oxide film 91 corresponding to the second region 1312 to be relatively low, the differential effects of the first region 1311 and the second region 1312 can be balanced, thereby ensuring the efficiency of the back-contact cell 100. Furthermore, by setting the ratio of oxygen to aluminum in the portion of the second aluminum oxide film 91 corresponding to the second region 1312 to be greater than the ratio of oxygen to aluminum in the first aluminum oxide film, the passivation effect of the cut surface 131 can be ensured.

[0184] In some embodiments, the thickness of the portion of the second aluminum oxide film layer 91 corresponding to the first region 1311 is greater than the thickness of the first aluminum oxide film layer.

[0185] In this way, the passivation effect at the first region 1311 which is more affected by the cutting force can be enhanced, thereby improving the performance of the back contact battery.

[0186] See also Figure 13 In some embodiments, a fourth region 124 is provided between the first region 121 and / or the second region 122 closest to the edge of the silicon substrate 10 and the edge of the silicon substrate 10 , and a third insulating dielectric layer 110 is provided on the fourth region 124 , and the thickness of the third insulating dielectric layer 110 is greater than the thickness of the first insulating dielectric layer 30 .

[0187] In this way, since the composite at the edge of the silicon substrate 10 is usually larger, a thicker third insulating dielectric layer 110 is set at a position close to the edge of the silicon substrate 10, which can improve the passivation effect at the edge of the silicon substrate 10, thereby ensuring the efficiency of the back contact battery 100.

[0188] Specifically, Figure 13 Only the second region 122 closest to the edge of the silicon substrate 10 is shown to have a third region 124 between it and the edge of the silicon substrate 10. It can be understood that the silicon substrate 10 has two opposite edges in the first direction, and the areas closest to the two edges can both be the first region 121, or both be the second region 122, or one side can be the first region 121 and the other side can be the second region 122. No specific limitation is made here.

[0189] Furthermore, in some embodiments, as described above, the first insulating dielectric layer 30 may include a first aluminum oxide film layer. The third insulating dielectric layer 110 may include a third aluminum oxide film layer, wherein the ratio of oxygen to aluminum in the third aluminum oxide film layer is greater than the ratio of oxygen to aluminum in the first aluminum oxide film layer.

[0190] In this way, setting the ratio of oxygen and aluminum in the third aluminum oxide film layer on the fourth region 124 located at the edge to be higher can further enhance the passivation effect of the fourth region 124 located at the edge, thereby enhancing the performance of the back contact battery.

[0191] Throughout this specification, references to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" indicate 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.

[0192] 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 back contact battery, characterized in that: include: A silicon substrate having a front side and a back side opposite to each other, the back side comprising a plurality of first regions and a plurality of second regions alternately arranged along a first direction, the back side further comprising an insulating region between the first regions and the second regions, the insulating region separating the first regions from the second regions, the first regions, the second regions, and the insulating spacer region all extending along a second direction, the second direction intersecting the first direction; a first passivation contact structure stacked on the first region; a first insulating dielectric layer, the first insulating dielectric layer comprising a main body portion stacked on the insulating region and an insulating extension portion extending and stacked to cover the entire first passivation contact structure; and a second passivation contact structure stacked on the second region, the second passivation contact structure having a polarity opposite to that of the first passivation contact structure, the second passivation contact structure comprising a first contact extension extending along a first direction and stacked over the body portion, and a second contact extension stacked over the insulating extension portion, a through-groove being formed in the stacked structure formed by the insulating extension portion and the second contact extension portion, and a portion of the first passivation contact structure being exposed from the through-groove; a first conductive structure, the first conductive structure being disposed at the through-groove and in conductive contact with the first passivation contact structure; and A second conductive structure is provided at least on a portion of the second passivation contact structure corresponding to the second region, and the second conductive structure is insulated from the first passivation contact structure and the first conductive structure.

2. The back contact battery according to claim 1, characterized in that The first passivation contact structure comprises a first passivation layer and a first doping layer sequentially stacked in a direction facing away from the back surface, and the second passivation contact structure comprises a second passivation layer and a second doping layer sequentially stacked in a direction facing away from the back surface; The first passivation layer is a tunneling oxide layer, the first doping layer is a doped polysilicon layer, the second passivation layer is at least one of an intrinsic amorphous silicon layer or a tunneling oxide layer, and the second doping layer is at least one of a doped amorphous silicon layer and a doped microcrystalline silicon layer.

3. The back contact battery according to claim 1, characterized in that The length of the insulating region in the first direction is 10 μm-600 μm.

4. The back contact battery according to claim 3, characterized in that The length of the insulating region in the first direction is 10 μm-300 μm.

5. The back contact battery according to claim 1, characterized in that The first area is a polished area, the insulating area is a suede area, and the thickness of the main body is smaller than the thickness of the insulating extension part.

6. The back contact battery according to claim 4, characterized in that The thickness of the main body portion may be 50 nm-100 nm, and the thickness of the insulating extension portion may be 60 nm-150 nm.

7. The back contact battery according to claim 6, characterized in that The ratio of the thickness of the insulating extension portion to the thickness of the main body portion is 1.1-2.

8. The back contact battery according to claim 1, characterized in that The first conductive structure includes a first transparent conductive film, and the first transparent conductive film is formed at least on a portion of the first passivation contact structure exposed from the through groove.

9. The back contact battery according to claim 8, characterized in that The first transparent conductive film is only disposed in the through groove, and the thickness of the first transparent conductive film is smaller than the thickness of the insulating extension portion.

10. The back contact battery according to claim 8, characterized in that The first area is a polished area, the insulating area is a velvet area, the first transparent conductive film has a first conductive extension portion extending along the second contact extension portion to the first contact extension portion, and the thickness of the first conductive extension portion is less than the thickness of the portion of the first transparent conductive film corresponding to the first area.

11. The back contact battery according to claim 10, characterized in that The thickness of the portion of the first transparent conductive film corresponding to the first region is 75 nm-150 nm, and the thickness of the first conductive extension portion is 40 nm-80 nm.

12. The back contact battery according to claim 10, characterized in that The ratio between the thickness of the portion of the first transparent conductive film corresponding to the first region and the thickness of the first conductive extension portion is 1.3-2.

13. The back contact battery according to claim 1, characterized in that The first conductive structure includes a metal electrode disposed at the through-groove, and the metal electrode at least fills the through-groove to be in conductive contact with the first passivation contact structure.

14. The back contact battery according to any one of claims 1 to 13, characterized in that The second conductive structure includes a second transparent conductive film, which is at least disposed on a portion of the second passivation contact structure corresponding to the second region and is in conductive contact with the second passivation contact structure.

15. The back contact battery according to claim 14, characterized in that The second region and the insulating region are both suede regions, and the surface roughness of the insulating region is greater than the surface roughness of the second region; The second transparent conductive film has a second conductive extension portion extending to cover at least a portion of the first contact extension portion, and a thickness of the second conductive extension portion is smaller than a thickness of a portion of the second transparent conductive film corresponding to the second region.

16. The back contact cell according to claim 15, characterized in that The thickness of the portion of the second transparent conductive film corresponding to the second region is 50 nm to 90 nm, and the thickness of the second conductive extension portion is 40 nm to 80 nm.

17. The back contact battery according to claim 15, characterized in that The ratio between the thickness of the portion of the second transparent conductive film corresponding to the second region and the thickness of the second conductive extension is 1.1-2.

18. The back contact battery according to claim 15, characterized in that The first area is a polishing area, and the second transparent conductive film further has a third conductive extension portion extending to cover a partial area of ​​the second contact extension portion, the third conductive extension portion is insulated from the first conductive structure, and the thickness of the third conductive extension portion is greater than the thickness of the portion of the second transparent conductive film corresponding to the second area and greater than the thickness of the second conductive extension portion.

19. The back contact battery according to claim 18, characterized in that The thickness of the third conductive extension portion is 75 nm to 150 nm, and the thickness of the portion of the second transparent conductive film corresponding to the second region is 50 nm to 90 nm.

20. The back contact cell according to claim 18, characterized in that The ratio of the thickness of the third conductive extension portion to the thickness of the portion of the second transparent conductive film corresponding to the second region is 1.1-1.

8.

21. The back contact cell according to claim 14, characterized in that The first area is a polished area, the second area is a suede area, the first conductive structure includes a first transparent conductive film, and is formed at least on the portion of the first passivation contact structure exposed from the through groove, and the thickness of the second transparent conductive film corresponding to the second area is less than the thickness of the first transparent conductive film corresponding to the first area.

22. The back contact cell according to claim 21, characterized in that The thickness of the portion of the first transparent conductive film corresponding to the first region is 75 nm to 150 nm, and the thickness of the portion of the second transparent conductive film corresponding to the second region is 50 nm to 90 nm.

23. The back contact cell according to claim 21, characterized in that The ratio between the thickness of the first transparent conductive film at a portion corresponding to the first region and the thickness of the second transparent conductive film at a portion corresponding to the second region is 1.1-1.

8.

24. The back contact battery according to claim 1, characterized in that There is a second insulating dielectric layer between the insulating extension portion and the first passivation contact structure, and the through groove also penetrates the second insulating dielectric layer. The second insulating dielectric layer has a suspended section extending along the first direction and protruding from the first area. The suspended section is suspended on the insulating area, and the first insulating dielectric layer and the first contact extension portion surround the suspended section in the first direction.

25. The back contact cell according to claim 24, characterized in that The thickness of the first insulating dielectric layer located on the side of the first passivation contact structure gradually decreases in the direction approaching the suspended section; the thickness of the first contact extension portion located on the side of the first passivation contact structure also gradually decreases in the direction approaching the suspended section.

26. The back contact cell according to claim 24, characterized in that The portion of the first insulating dielectric layer located on the surface of the suspended segment facing the silicon substrate gradually increases in the protruding direction of the suspended segment; the portion of the first contact extension portion located on the surface of the suspended segment facing the silicon substrate also gradually increases in the protruding direction of the suspended segment.

27. The back contact cell according to claim 1, characterized in that The front surface is a velvet surface, the insulating area is a velvet area, and the surface roughness of the insulating area is smaller than the surface roughness of the front surface.

28. The back contact cell according to claim 27, characterized in that A front passivation layer is formed on the front surface, and a thickness of the front passivation layer is smaller than a thickness of the main body.

29. The back contact cell according to claim 1, characterized in that The silicon substrate further has a plurality of side surfaces connecting the front surface and the back surface, at least some of the side surfaces have a side passivation layer, and the thickness of the side passivation layer is greater than the thickness of the first insulating dielectric layer.

30. The back contact cell according to claim 1, characterized in that The first insulating dielectric layer includes a first aluminum oxide film layer; The silicon substrate also has several side surfaces connecting the front and the back, and the several side surfaces include at least one cutting surface, and the cutting surface has a second aluminum oxide film layer. The cutting surface includes a first area connected to the back and a second area farther away from the back than the first area. The ratio of oxygen and aluminum elements in the part of the second aluminum oxide film layer corresponding to the first area is greater than the ratio of oxygen and aluminum elements in the first aluminum oxide film layer.

31. The back contact cell according to claim 30, characterized in that The ratio of oxygen to aluminum elements in the portion of the second aluminum oxide film layer corresponding to the first region is greater than the ratio of oxygen to aluminum elements in the portion of the second aluminum oxide film layer corresponding to the second region; and the ratio of oxygen to aluminum elements in the portion of the second aluminum oxide film layer corresponding to the second region is greater than the ratio of oxygen to aluminum elements in the first aluminum oxide film layer.

32. The back contact cell according to claim 30, characterized in that A thickness of a portion of the second aluminum oxide film layer corresponding to the first region is greater than a thickness of the first aluminum oxide film layer.

33. The back contact cell according to claim 1, characterized in that A fourth region is provided between the first region and / or the second region closest to the edge of the silicon substrate and the edge of the silicon substrate. A third insulating dielectric layer is provided on the fourth region. The thickness of the third insulating dielectric layer is greater than that of the first insulating dielectric layer.

34. The back contact cell according to claim 33, characterized in that The first insulating dielectric layer includes a first aluminum oxide film layer, and the third insulating dielectric layer includes a third aluminum oxide film layer. The ratio of oxygen to aluminum in the third aluminum oxide film layer is greater than the ratio of oxygen to aluminum in the first aluminum oxide film layer.

35. A battery assembly, characterized in that: A back contact battery comprising any one of several claims 1-34.

36. A photovoltaic system, characterized in that: A battery assembly comprising the battery assembly of claim 35.

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