Passivated contact solar cell

Abstract

The utility model provides a passivation contact solar cell with a back passivation anti-reflection layer having excellent passivation and anti-reflection performance at the same time, and the solar cell comprises a silicon substrate which is provided with a light receiving side and a back side; the tunneling oxide layer is arranged on the back side of the silicon substrate; the doped polycrystalline silicon layer is arranged on one side, opposite to the silicon substrate, of the tunneling oxide layer; the back passivation anti-reflection layer is arranged on one side, opposite to the silicon substrate, of the doped polycrystalline silicon layer and is continuously laid on a plane parallel to the thickness direction of the passivation contact solar cell, and a plurality of thinning regions which are mutually spaced are formed on the back passivation anti-reflection layer; the main body thickness of the back passivation anti-reflection layer is greater than the thickness of the back passivation anti-reflection layer in the thinning area; the back metal electrode layer comprises a plurality of back metal electrodes in one-to-one correspondence with the thinning areas, the back metal electrodes are located in the corresponding thinning areas and penetrate through the back passivation anti-reflection layer to be in contact with the doped polycrystalline silicon layer, and the projections of the back metal electrodes on the back passivation anti-reflection layer are located in the corresponding thinning areas.

Description

Technical Field

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

[0002] TOPCon cell is a passivated contact cell. Its structure is to prepare an ultra-thin silicon oxide layer and a highly doped polysilicon layer on the silicon surface. The selective permeability of ultra-thin silicon oxide to carriers and the good field passivation effect of highly doped polysilicon and substrate are used to effectively inhibit the recombination of minority carriers on the silicon surface and improve the cell opening voltage. However, the thicker polysilicon layer of the TOPCon cell brings serious parasitic absorption. Thinning the polysilicon layer on the back can greatly reduce the parasitic absorption, ensure the cell opening voltage, and increase the current density, thereby improving the cell conversion efficiency.

[0003] A key to obtaining high-efficiency TOPCon solar cells is to prepare a thinner polysilicon layer while ensuring the passivation performance of the back side. However, as the polysilicon layer becomes thinner, the tolerance window of the thin polysilicon layer to the slurry ablation becomes narrower. In the subsequent metallization process, the polysilicon and tunnel oxide layer are easily damaged, resulting in a significant reduction in the passivation effect.

[0004] Therefore, there is an urgent need for a passivated contact solar cell that avoids the parasitic absorption of the thick polysilicon layer while ensuring the back passivation effect and contact performance. Summary of the invention

[0005] The present application provides a passivated contact solar cell, comprising:

[0006] a silicon substrate having a light-receiving side and a back side;

[0007] A tunneling oxide layer is disposed on the back side of the silicon substrate;

[0008] A doped polysilicon layer is disposed on a side of the tunnel oxide layer facing away from the silicon substrate;

[0009] A back passivation anti-reflection layer is arranged on the side of the doped polysilicon layer facing away from the silicon substrate and is continuously laid on a plane parallel to the thickness direction of the passivation contact solar cell, the back passivation anti-reflection layer is formed with a plurality of thinning regions spaced apart from each other, and the main body thickness of the back passivation anti-reflection layer is greater than the thickness of the back passivation anti-reflection layer in the thinning region;

[0010] The back metal electrode layer includes a plurality of back metal electrodes corresponding one to one with the plurality of thinning regions. The back metal electrodes are located in the corresponding thinning regions and contact the doped polysilicon layer through the back passivation anti-reflection layer. The projection of the back metal electrodes on the back passivation anti-reflection layer is located in the corresponding thinning regions.

[0011] The passivated contact solar cell provided by the present application reduces the thickness of the back passivation anti-reflection layer in the thinned area by setting a plurality of thinning areas corresponding to the back metal electrode in the back passivation anti-reflection layer, which can match the lower slurry temperature in the metallization process, so that the metal slurry can be burned through the back passivation anti-reflection layer at a lower sintering temperature during the metallization process without damaging the thin doped polysilicon layer. In other words, the sintering process window belongs to the tolerance window of the thin polysilicon layer to the ablation of the slurry, thereby avoiding the ablation damage of the slurry to the passivation contact structure (tunneling oxide layer + doped polysilicon layer) during the metallization process to the greatest extent. Different from the optical mismatch (mainly overflow loss and back reflection loss) caused by the overall thinning process of the back passivation anti-reflection layer in the embodiment of the present application, the embodiment of the present application proposes a local thinning scheme for the back passivation anti-reflection layer, which can make the back passivation anti-reflection layer have excellent passivation and anti-reflection performance at the same time, and the back passivation anti-reflection layer can take into account the effects in both optical and passivation aspects.

[0012] In some optional embodiments of the present application, in the thickness direction of the passivated contact solar cell, at least one side of the back metal electrode is arranged in contact with a portion of the back passivation anti-reflection layer in the thinned area.

[0013] In some optional embodiments of the present application, the back side passivation anti-reflection layer is a single film layer, and the back side passivation anti-reflection layer is formed of silicon nitride material.

[0014] In some optional embodiments of the present application, the thickness of the back passivation anti-reflection layer in the thinned area is 10nm to 70nm less than the thickness of the back passivation anti-reflection layer in the main area, and the main area is not thinned.

[0015] In some optional embodiments of the present application, the back passivation anti-reflection layer is a composite film layer, and the back passivation anti-reflection layer includes at least two back passivation anti-reflection sub-film layers.

[0016] In some optional embodiments of the present application, the material of the back passivation anti-reflection film layer is selected from aluminum oxide, silicon oxide, gallium oxide, silicon nitride, aluminum nitride, silicon oxynitride and aluminum oxynitride;

[0017] In some optional embodiments of the present application, the back passivation anti-reflection layer includes a silicon nitride film layer, a silicon oxynitride film layer and a silicon oxide film layer stacked in sequence from the silicon substrate to the back metal electrode layer.

[0018] In some optional embodiments of the present application, the silicon oxide film layer in the thinned area is thinned, and the thickness of the back passivation anti-reflection layer in the thinned area is 10nm to 30nm less than the thickness of the back passivation anti-reflection layer in the main area.

[0019] In some optional embodiments of the present application, the silicon oxynitride film layer in the thinned area is thinned, and the thickness of the back passivation anti-reflection layer in the thinned area is reduced by 10nm to 30nm compared with the thickness of the back passivation anti-reflection layer in the main area.

[0020] In some optional embodiments of the present application, the silicon nitride film layer in the thinning area is thinned, and the thickness of the back passivation anti-reflection layer in the thinning area is 2nm to 40nm less than the thickness of the back passivation anti-reflection layer in the main area.

[0021] In some optional embodiments of the present application, the silicon nitride film layer and the silicon nitride oxide film layer in the thinned area are both thinned, and the thickness of the back passivation anti-reflection layer in the thinned area is 35nm to 60nm less than the thickness of the back passivation anti-reflection layer in the main area.

[0022] In some optional embodiments of the present application, the thickness of the silicon nitride film layer in the main area of ​​the back passivation anti-reflection layer that has not been thinned is 40 nm, the thickness of the silicon oxynitride film layer is 30 nm, and the thickness of the silicon oxide film layer is 30 nm. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 Schematic diagram of the unmetallized layer structure of the passivation contact solar cell in Example 1 of the present application;

[0025] Figure 2 It is a schematic diagram of the layer structure after metallization of the passivation contact solar cell in Example 1 of the present application;

[0026] Figure 3 This is a schematic diagram of the unmetallized layer structure of the passivation contact solar cell in Example 2 of the present application;

[0027] Figure 4 It is a schematic diagram of the layer structure after metallization of the passivation contact solar cell in Example 2 of the present application;

[0028] Figure 5 This is a schematic diagram of the unmetallized layer structure of the passivation contact solar cell in Example 3 of the present application;

[0029] Figure 6 It is a schematic diagram of the layer structure after metallization of the passivation contact solar cell in Example 3 of the present application;

[0030] Figure 7 Schematic diagram of the unmetallized layer structure of the passivation contact solar cell in Example 4 of the present application;

[0031] Figure 8 It is a schematic diagram of the layer structure after metallization of the passivation contact solar cell in Example 4 of the present application;

[0032] Fig. 9 This is a schematic diagram of the unmetallized layer structure of the passivation contact solar cell in Example 5 of the present application;

[0033] Fig.10 It is a schematic diagram of the layer structure of the passivation contact solar cell after metallization in Example 5 of the present application.

[0034] Description of reference numerals:

[0035] Silicon substrate-1; p+ emitter-2; front passivation anti-reflection layer-3; tunneling oxide layer-4; doped polysilicon layer-5; back passivation anti-reflection layer-6; silicon nitride film layer-6a; silicon oxynitride film layer-6b; silicon oxide film layer-6c; thinning area-7; main area-71; front metal electrode-8; back metal electrode-9. DETAILED DESCRIPTION

[0036] The technical solution of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0037] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0038] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0039] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0040] Combine the following Figures 1 to 10 The structure of the passivation contact solar cell in the embodiment of the present application is described.

[0041] like Figure 2 As shown, the present application provides a passivated contact solar cell, comprising:

[0042] A silicon substrate 1 having a light receiving side and a back side;

[0043] A tunneling oxide layer 4 is disposed on the back side of the silicon substrate 1;

[0044] The doped polysilicon layer 5 is disposed on the side of the tunnel oxide layer 4 facing away from the silicon substrate 1;

[0045] A back passivation anti-reflection layer 6 is arranged on the side of the doped polysilicon layer 5 facing away from the silicon substrate 1 and is continuously laid on a plane parallel to the thickness direction of the passivation contact solar cell. The back passivation anti-reflection layer 6 is formed with a plurality of thinning regions 7 spaced apart from each other. The main body thickness of the back passivation anti-reflection layer 6 is greater than the thickness of the back passivation anti-reflection layer 6 in the thinning region 7.

[0046] The back metal electrode 9 layer includes multiple back metal electrodes 9 corresponding to the multiple thinning areas 7 one by one. The back metal electrode 9 is located in the corresponding thinning area 7 and passes through the back passivation anti-reflection layer 6 to contact the doped polysilicon layer 5. The projection of the back metal electrode 9 on the back passivation anti-reflection layer 6 is located in the corresponding thinning area 7.

[0047] The passivated contact solar cell provided by the present application is provided with a plurality of thinning regions 7 corresponding to the back metal electrode 9 in the back passivation anti-reflection layer 6, so that the thickness of the back passivation anti-reflection layer 6 in the thinning region 7 is reduced, which can match the lower slurry temperature in the metallization process, so that the metal slurry can be burned through the back passivation anti-reflection layer 6 at a lower sintering temperature in the metallization process without damaging the thin doped polysilicon layer 5. In other words, the sintering process window belongs to the tolerance window of the thin polysilicon layer to the ablation of the slurry, thereby avoiding the ablation damage of the slurry to the passivation contact structure (tunneling oxide layer 4 + doped polysilicon layer 5) during the metallization process to the greatest extent. Different from the optical mismatch (mainly overflow loss and back reflection loss) caused by the overall thinning process of the back passivation anti-reflection layer 6 in the embodiment of the present application, the embodiment of the present application proposes a local thinning scheme for the back passivation anti-reflection layer 6, which can take into account the optimization of the back passivation anti-reflection layer 6 in both optics and passivation.

[0048] Overflow loss: light that cannot be absorbed by the entire cell structure.

[0049] Back reflection loss: optical loss caused by the inability of the back film to reflect back to the battery matrix due to overall thinning.

[0050] In some optional embodiments of the present application, the silicon substrate 1 is an n-type silicon substrate 1, and a P+ emitter 2, a front passivation anti-reflection layer 3, and a front metal electrode 8 layer are sequentially stacked on the light-receiving side of the n-type silicon substrate 1. The front passivation anti-reflection layer 3 is a composite film layer formed by an aluminum oxide film layer and a silicon nitride film layer 6a, and the front metal electrode 8 in the front metal electrode 8 layer penetrates the front passivation anti-reflection layer 3 and is in contact with the P+ emitter 2.

[0051] In some optional embodiments of the present application, the front passivation anti-reflection layer 3 includes at least one of aluminum oxide, silicon oxide, gallium oxide, silicon nitride, aluminum nitride, and silicon oxynitride.

[0052] In some optional embodiments of the present application, the tunneling oxide layer 4 is formed of silicon oxide, and the thickness of the tunneling oxide layer 4 is 0.5 nm to 3 nm.

[0053] The doped polysilicon layer 5 is an n+ doped polysilicon layer 5 with a thickness of 10 nm to 80 nm.

[0054] In some optional embodiments of the present application, the back passivation anti-reflection layer 6 is a single film layer, and the back passivation anti-reflection layer 6 is formed of silicon nitride material.

[0055] In some optional embodiments of the present application, the thickness of the back passivation anti-reflection layer 6 in the thinned area 7 is 10nm to 70nm less than the thickness of the back passivation anti-reflection layer 6 in the main area 71, and the main area 71 is not thinned.

[0056] like Figure 1 As shown, in some optional embodiments of the present application, a precursor of a passivated contact solar cell is provided before the metallization process step, and the precursor of the passivated contact solar cell includes: a silicon substrate 1, a P+ emitter 2, a front passivation anti-reflection layer 3, which are sequentially stacked on the light-receiving side of the silicon substrate 1 away from the light incident direction, and a tunneling oxide layer 4, a doped polysilicon layer 5, and a back passivation anti-reflection layer 6, which are sequentially stacked on the back side of the silicon substrate 1 along the light incident direction. In these embodiments, the back passivation anti-reflection layer 6 is a single film layer, and the back passivation anti-reflection layer 6 is formed of silicon nitride material.

[0057] In some specific examples, the thickness of the back passivation anti-reflection layer 6 in the thinned area 7 is 10 nm to 70 nm less than the thickness of the back passivation anti-reflection layer 6 in the main area 71 , and the main area 71 is not thinned.

[0058] In these embodiments, the thinning process of the back passivation anti-reflection layer 6 is completed by a non-laser process such as deposition, which effectively avoids laser film damage and forms a thinned area 7 on the back passivation anti-reflection layer 6 .

[0059] In some specific examples, the preparation process of the back passivation anti-reflection layer 6 is as follows: ① first, the base layer of the back passivation anti-reflection layer 6 is deposited on the entire surface, and the base layer reaches the target thickness required for the thinning area 7; ② then the thinning area 7 is covered by a mask plate, and a secondary deposition is performed to make the main area 71 reach the target thickness, thereby completing the setting requirements of different thicknesses in different areas of the entire back passivation anti-reflection layer 6.

[0060] like Figure 2 As shown, the precursor of the passivated contact solar cell is metallized, and the metal paste is printed into the thinned area 7 by screen printing process, and then sintered to form a front metal electrode 8 and a back metal electrode 9. The front metal electrode 8 penetrates the front passivation anti-reflection layer 3 and is in contact with the P+ emitter 2. The back metal electrode 9 penetrates the back passivation anti-reflection layer 6 and is in contact with the doped polycrystalline layer in the thinned area 7.

[0061] In some optional embodiments of the present application, in the thickness direction of the passivated contact solar cell, at least one side of the back metal electrode 9 is arranged in contact with the portion of the back passivation anti-reflection layer 6 in the thinned area 7. In these embodiments, the back metal electrode 9 needs to pass through the portion of the back passivation anti-reflection layer 6 in the thinned area 7, and the side of the back metal electrode 9 is arranged in contact with the portion of the back passivation anti-reflection layer 6 in the thinned area 7.

[0062] In some optional embodiments of the present application, the back metal electrode 9 is a grid electrode, and the width of the back metal electrode 9 is less than or equal to the width of the thinned region 7. In some specific examples of these embodiments, the width of the back metal electrode 9 is less than the width of the thinned region 7. In the thinned region 7, due to the thinning process of the back passivation anti-reflection layer 6, there is a gap between the side of the back metal electrode 9 and the portion of the back passivation anti-reflection layer 6 in the main region 71 in the thinned region 7.

[0063] In some optional embodiments of the present application, the back passivation anti-reflection layer 6 is a composite film layer, and the back passivation anti-reflection layer 6 includes at least two back passivation anti-reflection sub-film layers.

[0064] In some optional embodiments of the present application, the material of the back side passivation anti-reflection film layer is selected from aluminum oxide, silicon oxide, gallium oxide, silicon nitride, aluminum nitride, silicon oxynitride and aluminum oxynitride.

[0065] In some optional embodiments of the present application, the back passivation anti-reflection layer 6 includes a silicon nitride film layer 6a, a silicon oxynitride film layer 6b and a silicon oxide film layer 6c stacked in sequence from the silicon substrate 1 to the back metal electrode 9 layer.

[0066] like Figure 3 As shown, in some optional embodiments of the present application, the back passivation anti-reflection layer 6 includes a silicon nitride film layer 6a, a silicon oxynitride film layer 6b and a silicon oxide film layer 6c stacked in sequence from the silicon substrate 1 to the back metal electrode 9 layer. Before the precursor of the passivation contact solar cell is metallized, the silicon oxide film layer 6c in the thinning area 7 is thinned, and the thickness of the back passivation anti-reflection layer 6 in the thinning area 7 is reduced by 10nm to 30nm compared with the thickness of the back passivation anti-reflection layer 6 in the main area 71. In these embodiments, the thickness of the silicon oxide film layer 6c of the back passivation anti-reflection layer 6 in the thinning area 7 is less than the thickness of the silicon oxide film layer 6c of the back passivation anti-reflection layer 6 in the main area 71, so that the thinning area 7 forms a groove structure concave toward the silicon substrate 1.

[0067] In these embodiments, when the back passivation anti-reflection layer 6 is formed by stacking at least two back passivation anti-reflection film layers, it is preferred to thin the outermost back passivation anti-reflection film layer compared to the silicon substrate 1, so as to avoid thinning the inner hydrogen-rich passivation film, thereby ensuring the deposition quality of the outermost back passivation anti-reflection film layer.

[0068] like Figure 4As shown, the precursor of the passivated contact solar cell is metallized, and the metal paste is printed into the thinned area 7 by screen printing process, and then sintered to form a front metal electrode 8 and a back metal electrode 9. The front metal electrode 8 penetrates the front passivation anti-reflection layer 3 and is in contact with the P+ emitter 2. The back metal electrode 9 penetrates the back passivation anti-reflection layer 6 and is in contact with the doped polycrystalline layer in the thinned area 7.

[0069] In some optional embodiments of the present application, in the thickness direction of the passivated contact solar cell, at least one side of the back metal electrode 9 is arranged in contact with the portion of the back passivation anti-reflection layer 6 in the thinned area 7. In these embodiments, the back metal electrode 9 needs to pass through the portion of the back passivation anti-reflection layer 6 in the thinned area 7, and the side of the back metal electrode 9 is arranged in contact with the portion of the back passivation anti-reflection layer 6 in the thinned area 7.

[0070] In some optional embodiments of the present application, the back metal electrode 9 is a grid electrode, and the width of the back metal electrode 9 is less than or equal to the width of the thinned region 7. In some specific examples of these embodiments, the width of the back metal electrode 9 is less than the width of the thinned region 7. In the thinned region 7, due to the thinning process of the back passivation anti-reflection layer 6, there is a gap between the side of the back metal electrode 9 and the portion of the back passivation anti-reflection layer 6 in the main region 71 in the thinned region 7.

[0071] like Figure 5 As shown, in some optional embodiments of the present application, the back passivation anti-reflection layer 6 includes a silicon nitride film layer 6a, a silicon oxynitride film layer 6b and a silicon oxide film layer 6c stacked in sequence from the silicon substrate 1 to the back metal electrode 9 layer. Before the precursor of the passivation contact solar cell is metallized, the silicon oxynitride film layer 6b in the thinning area 7 is thinned, and the thickness of the back passivation anti-reflection layer 6 in the thinning area 7 is reduced by 10nm to 30nm compared with the thickness of the back passivation anti-reflection layer 6 in the main area 71. In these embodiments, the thickness of the silicon oxynitride film layer 6b in the thinning area 7 of the back passivation anti-reflection layer 6 is less than the thickness of the silicon oxynitride film layer 6b in the main area 71 of the back passivation anti-reflection layer 6, so that the thinning area 7 forms a groove structure concave toward the silicon substrate 1.

[0072] like Figure 6 As shown, the precursor of the passivated contact solar cell is metallized, and the metal paste is printed into the thinned area 7 by screen printing process, and then sintered to form a front metal electrode 8 and a back metal electrode 9. The front metal electrode 8 penetrates the front passivation anti-reflection layer 3 and is in contact with the P+ emitter 2. The back metal electrode 9 penetrates the back passivation anti-reflection layer 6 and is in contact with the doped polycrystalline layer in the thinned area 7.

[0073] In some optional embodiments of the present application, in the thickness direction of the passivated contact solar cell, at least one side of the back metal electrode 9 is arranged in contact with the portion of the back passivation anti-reflection layer 6 in the thinned area 7. In these embodiments, the back metal electrode 9 needs to pass through the portion of the back passivation anti-reflection layer 6 in the thinned area 7, and the side of the back metal electrode 9 is arranged in contact with the portion of the back passivation anti-reflection layer 6 in the thinned area 7.

[0074] In some optional embodiments of the present application, the back metal electrode 9 is a grid electrode, and the width of the back metal electrode 9 is less than or equal to the width of the thinned region 7. In some specific examples of these embodiments, the width of the back metal electrode 9 is less than the width of the thinned region 7. In the thinned region 7, due to the thinning process of the back passivation anti-reflection layer 6, there is a gap between the side of the back metal electrode 9 and the portion of the back passivation anti-reflection layer 6 in the main region 71 in the thinned region 7.

[0075] like Figure 7 As shown, in some optional embodiments of the present application, the back passivation anti-reflection layer 6 includes a silicon nitride film layer 6a, a silicon nitride oxide film layer 6b and a silicon oxide film layer 6c stacked in sequence from the silicon substrate 1 to the back metal electrode 9 layer. Before the precursor of the passivation contact solar cell is metallized, the silicon nitride film layer 6a in the thinning area 7 is thinned, and the thickness of the back passivation anti-reflection layer 6 in the thinning area 7 is reduced by 2nm to 40nm compared with the thickness of the back passivation anti-reflection layer 6 in the main area 71. In these embodiments, the thickness of the silicon nitride film layer 6a of the back passivation anti-reflection layer 6 in the thinning area 7 is less than the thickness of the silicon nitride film layer 6a of the back passivation anti-reflection layer 6 in the main area 71, so that the thinning area 7 forms a groove structure concave toward the silicon substrate 1.

[0076] like Figure 8 As shown, the precursor of the passivated contact solar cell is metallized, and the metal paste is printed into the thinned area 7 by screen printing process, and then sintered to form a front metal electrode 8 and a back metal electrode 9. The front metal electrode 8 penetrates the front passivation anti-reflection layer 3 and is in contact with the P+ emitter 2. The back metal electrode 9 penetrates the back passivation anti-reflection layer 6 and is in contact with the doped polycrystalline layer in the thinned area 7.

[0077] In some optional embodiments of the present application, in the thickness direction of the passivated contact solar cell, at least one side of the back metal electrode 9 is arranged in contact with the portion of the back passivation anti-reflection layer 6 in the thinned area 7. In these embodiments, the back metal electrode 9 needs to pass through the portion of the back passivation anti-reflection layer 6 in the thinned area 7, and the side of the back metal electrode 9 is arranged in contact with the portion of the back passivation anti-reflection layer 6 in the thinned area 7.

[0078] In some optional embodiments of the present application, the back metal electrode 9 is a grid electrode, and the width of the back metal electrode 9 is less than or equal to the width of the thinned region 7. In some specific examples of these embodiments, the width of the back metal electrode 9 is less than the width of the thinned region 7. In the thinned region 7, due to the thinning process of the back passivation anti-reflection layer 6, there is a gap between the side of the back metal electrode 9 and the portion of the back passivation anti-reflection layer 6 in the main region 71 in the thinned region 7.

[0079] like Fig. 9 As shown, in some optional embodiments of the present application, the back passivation anti-reflection layer 6 includes a silicon nitride film layer 6a, a silicon oxynitride film layer 6b and a silicon oxide film layer 6c stacked in sequence from the silicon substrate 1 to the back metal electrode 9. Before the precursor of the passivation contact solar cell is metallized, the silicon nitride film layer 6a and the silicon oxynitride film layer 6b in the thinning area 7 are both thinned, and the thickness of the back passivation anti-reflection layer 6 in the thinning area 7 is reduced by 35nm to 60nm compared with the thickness of the back passivation anti-reflection layer 6 in the main area 71. In these embodiments, the thickness of the silicon nitride film layer 6a of the back passivation anti-reflection layer 6 in the thinning area 7 is less than the thickness of the silicon nitride film layer 6a of the back passivation anti-reflection layer 6 in the main area 71, and the thickness of the silicon oxynitride film layer 6b of the back passivation anti-reflection layer 6 in the thinning area 7 is less than the thickness of the silicon oxynitride film layer 6b of the back passivation anti-reflection layer 6 in the main area 71, so that the thinning area 7 forms a groove structure concave toward the silicon substrate 1.

[0080] like Fig.10 As shown, the precursor of the passivated contact solar cell is metallized, and the metal paste is printed into the thinned area 7 by screen printing process, and then sintered to form a front metal electrode 8 and a back metal electrode 9. The front metal electrode 8 penetrates the front passivation anti-reflection layer 3 and is in contact with the P+ emitter 2. The back metal electrode 9 penetrates the back passivation anti-reflection layer 6 and is in contact with the doped polycrystalline layer in the thinned area 7.

[0081] In some optional embodiments of the present application, in the thickness direction of the passivated contact solar cell, at least one side of the back metal electrode 9 is arranged in contact with the portion of the back passivation anti-reflection layer 6 in the thinned area 7. In these embodiments, the back metal electrode 9 needs to pass through the portion of the back passivation anti-reflection layer 6 in the thinned area 7, and the side of the back metal electrode 9 is arranged in contact with the portion of the back passivation anti-reflection layer 6 in the thinned area 7.

[0082] In some optional embodiments of the present application, the back metal electrode 9 is a grid electrode, and the width of the back metal electrode 9 is less than or equal to the width of the thinned region 7. In some specific examples of these embodiments, the width of the back metal electrode 9 is less than the width of the thinned region 7. In the thinned region 7, due to the thinning process of the back passivation anti-reflection layer 6, there is a gap between the side of the back metal electrode 9 and the portion of the back passivation anti-reflection layer 6 in the main region 71 in the thinned region 7.

[0083] In the embodiment of the present application, in the main region 71 of the back passivation anti-reflection layer 6 that has not been thinned, the thickness of the silicon nitride film layer 6a is 40 nm, the thickness of the silicon oxynitride film layer 6b is 30 nm, and the thickness of the silicon oxide film layer 6c is 30 nm.

[0084] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A passivated contact solar cell, characterized in that: include: a silicon substrate having a light-receiving side and a back side; A tunneling oxide layer is disposed on the back side of the silicon substrate; A doped polysilicon layer is disposed on a side of the tunnel oxide layer facing away from the silicon substrate; A back passivation anti-reflection layer is arranged on a side of the doped polysilicon layer facing away from the silicon substrate and is continuously laid on a plane parallel to the thickness direction of the passivation contact solar cell, wherein the back passivation anti-reflection layer is formed with a plurality of thinning regions spaced apart from each other, and the main body thickness of the back passivation anti-reflection layer is greater than the thickness of the back passivation anti-reflection layer in the thinning region; A back metal electrode layer comprises a plurality of back metal electrodes corresponding one by one to the plurality of thinning regions, wherein the back metal electrodes are located in the corresponding thinning regions and contact the doped polysilicon layer through the back passivation anti-reflection layer, and the projection of the back metal electrodes on the back passivation anti-reflection layer is located in the corresponding thinning regions.

2. The passivated contact solar cell according to claim 1, characterized in that: In the thickness direction of the passivated contact solar cell, at least one side of the back metal electrode is arranged in contact with a portion of the back passivation anti-reflection layer in the thinned area.

3. The passivated contact solar cell according to claim 1, characterized in that: The back passivation anti-reflection layer is a single film layer, and the back passivation anti-reflection layer is formed of silicon nitride material.

4. The passivated contact solar cell according to claim 3, characterized in that: The thickness of the back passivation anti-reflection layer in the thinned area is 10 nm to 70 nm less than the thickness of the back passivation anti-reflection layer in the main area, and the main area is not thinned.

5. The passivated contact solar cell according to claim 1, characterized in that: The back passivation anti-reflection layer is a composite film layer, and the back passivation anti-reflection layer includes at least two back passivation anti-reflection sub-film layers.

6. The passivated contact solar cell according to claim 5, characterized in that: The back passivation anti-reflection layer comprises a silicon nitride film layer, a silicon oxynitride film layer and a silicon oxide film layer which are sequentially stacked from the silicon substrate to the back metal electrode layer.

7. The passivated contact solar cell according to claim 6, characterized in that: The silicon oxide film layer in the thinned area is thinned, and the thickness of the back passivation anti-reflection layer in the thinned area is 10nm to 30nm less than the thickness of the back passivation anti-reflection layer in the main area.

8. The passivated contact solar cell according to claim 6, characterized in that: The silicon oxynitride film layer in the thinned area is thinned, and the thickness of the back passivation anti-reflection layer in the thinned area is 10nm to 30nm less than the thickness of the back passivation anti-reflection layer in the main area.

9. The passivated contact solar cell according to claim 6, characterized in that: The silicon nitride film layer in the thinned area is thinned, and the thickness of the back passivation anti-reflection layer in the thinned area is 2nm to 40nm less than the thickness of the back passivation anti-reflection layer in the main area.

10. The passivated contact solar cell according to claim 6, characterized in that: The silicon nitride film layer and the silicon nitride oxide film layer in the thinned area are both thinned, and the thickness of the back passivation anti-reflection layer in the thinned area is 35nm to 60nm less than the thickness of the back passivation anti-reflection layer in the main area.

11. The passivated contact solar cell according to any one of claims 7 to 10, characterized in that: In the main area of ​​the back passivation anti-reflection layer that has not been thinned, the thickness of the silicon nitride film layer is 40 nm, the thickness of the silicon oxynitride film layer is 30 nm, and the thickness of the silicon oxide film layer is 30 nm.

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