TOPCon battery, preparation method thereof and photovoltaic module

Abstract

The invention discloses a TOPCon battery and a preparation method thereof, and a photovoltaic module, and the TOPCon battery comprises an N-type silicon substrate which is provided with a light receiving surface and a backlight surface, which are opposite to each other; the light receiving surface comprises a first area and a second area; a P-type emitter layer, a first passivation layer and a first antireflection layer are sequentially arranged on the first region in the direction away from the N-type silicon substrate; the first region is also provided with a first metal electrode, and the first metal electrode passes through the first antireflection layer and the first passivation layer and is in contact with the P-type emitter layer; and a second passivation layer and a second antireflection layer are sequentially arranged on the second region along the direction far away from the N-type silicon substrate. The P-type emitter layer is selectively arranged on the light receiving surface of the N-type silicon substrate, so that the conversion efficiency of the cell is remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of solar cells, and in particular to a TOPCon cell and a preparation method thereof, and a photovoltaic module. Background Art

[0002] TOPCon (Tunnel Oxide Passivated Contact) batteries have become mainstream battery products due to their high efficiency and low attenuation properties. How to further improve the conversion efficiency has become a bottleneck restricting its development.

[0003] In conventional TOPCon cell structures, the surface passivation performance of the boron-doped P-type emitter restricts further improvement of cell efficiency. In related technologies, the passivation performance of the P-type emitter is improved by reducing the doping concentration of the P-type emitter to reduce recombination, but at the same time, it will increase the metal contact recombination and attenuate the carrier transport performance, which is not conducive to improving the photoelectric conversion efficiency of the TOPCon cell. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, one object of the present invention is to provide a TOPCon cell with high photoelectric conversion efficiency.

[0005] Specifically, the first aspect of the present invention provides a TOPCon cell, comprising: an N-type silicon substrate, the N-type silicon substrate having a light-receiving surface and a backlight surface opposite to each other; the light-receiving surface comprises a first region and a second region;

[0006] A P-type emitter layer, a first passivation layer, and a first anti-reflection layer are sequentially arranged on the first region in a direction away from the N-type silicon substrate; a first metal electrode is also arranged on the first region, the first metal electrode passes through the first anti-reflection layer and the first passivation layer and contacts the P-type emitter layer;

[0007] A second passivation layer and a second anti-reflection layer are sequentially disposed on the second region in a direction away from the N-type silicon substrate.

[0008] By selectively setting a P-type emitter layer on the light-receiving surface of the N-type silicon substrate, that is, setting a P-type emitter layer in the first area and not setting a P-type emitter layer in the second area, this can not only ensure the carrier separation capability, but also enable the substrate in the second area (that is, the undoped area) to be directly passivated. Since the surface recombination of the undoped area is much smaller than that of the boron-doped area, the conversion efficiency of the battery can be improved through the selective distribution of the P-type emitter layer.

[0009] According to some embodiments of the present invention, the area of ​​the first region accounts for 40%-60%, preferably 45%-55% of the total area of ​​the light-receiving surface. Optimizing the area ratio of the first region is conducive to reducing surface recombination and improving the conversion efficiency of the battery.

[0010] According to some embodiments of the present invention, the backlight surface includes a third area and a fourth area; a tunneling oxide layer, an N-type polysilicon layer, a third passivation layer and a third anti-reflection layer are sequentially arranged on the third area in a direction away from the N-type silicon substrate; a second metal electrode is also arranged on the third area, the second metal electrode passes through the third anti-reflection layer and the third passivation layer and contacts the N-type polysilicon layer; a fourth passivation layer and a fourth anti-reflection layer are sequentially arranged on the fourth area in a direction away from the N-type silicon substrate. The back N-type polysilicon layer is selectively distributed, so that the thickness of the N-type polysilicon layer in the third area (i.e., the metal contact area) is guaranteed, and the metallization composite is not affected. At the same time, the N-type polysilicon layer in the fourth area (i.e., the non-metal contact area) is removed, which can greatly reduce parasitic absorption, improve the utilization rate of incident light, and thus improve the conversion efficiency of the battery.

[0011] According to some embodiments of the present invention, the area of ​​the third region accounts for 30%-60%, preferably 40%-50% of the total area of ​​the backlight surface. Optimizing the area ratio of the third region is conducive to reducing parasitic absorption and improving the conversion efficiency of the battery.

[0012] According to some embodiments of the present invention, the TOPCon cell satisfies at least one of the following conditions:

[0013] (1) The thickness of the first passivation layer and the second passivation layer are both 2nm-10nm;

[0014] (2) The thickness of the first anti-reflection layer and the second anti-reflection layer are both 60nm-100nm;

[0015] (3) The thickness of the tunnel oxide layer is 0.5 nm to 2.5 nm;

[0016] (4) The thickness of the N-type polysilicon layer is 10 nm to 300 nm;

[0017] (5) The thickness of the third passivation layer and the fourth passivation layer are both 2nm-10nm;

[0018] (6) The thickness of the third anti-reflection layer and the fourth anti-reflection layer are both 60nm-100nm;

[0019] (7) The P-type emitter layer is a boron-doped P-type emitter layer;

[0020] (8) The N-type polysilicon layer is a phosphorus-doped N-type polysilicon layer.

[0021] The second aspect of the present invention provides a method for preparing a TOPCon battery according to the first aspect of the present invention, comprising the following steps:

[0022] Providing an N-type silicon substrate, wherein the N-type silicon substrate has a light-receiving surface and a backlight surface opposite to each other;

[0023] forming a P-type emitter layer on the first region of the light-receiving surface;

[0024] forming a passivation layer and an anti-reflection layer in sequence on the P-type emitter layer and the second region of the light-receiving surface in a direction away from the N-type silicon substrate;

[0025] A first metal electrode is formed so that the first metal electrode passes through the anti-reflection layer and the passivation layer in the first region and contacts the P-type emitter layer.

[0026] The method of the present invention has the advantages of simple process scheme, low cost, etc., and the process of the present invention can be formed by making appropriate adjustments on the basis of the existing process.

[0027] According to some embodiments of the present invention, forming a P-type emitter layer on the first region of the light-receiving surface includes: forming a P-type emitter layer on the entire light-receiving surface of the N-type silicon substrate; and removing the P-type emitter layer on the second region.

[0028] According to some embodiments of the present invention, forming a P-type emitter layer on the first area of ​​the light-receiving surface includes: sequentially performing texturing and boron diffusion on the light-receiving surface of the N-type silicon substrate to form a P-type emitter layer and a borosilicate glass layer; removing the borosilicate glass layer on the second area; removing the P-type emitter layer on the second area and performing secondary texturing on the second area; and removing the borosilicate glass layer on the first area.

[0029] According to some embodiments of the present invention, a laser is used to remove the borosilicate glass layer on the second region; an alkaline solution is used to remove the P-type emitter layer on the second region and the second region is subjected to secondary texturing; the alkaline solution includes at least one of a KOH solution and a NaOH solution.

[0030] According to some embodiments of the present invention, after forming a P-type emitter layer and a borosilicate glass layer and before removing the borosilicate glass layer on the second region, the method further includes: sequentially forming a tunneling oxide layer, an N-type polysilicon layer and a phosphosilicate glass layer on the backlight surface; after forming the phosphosilicate glass layer, the method further includes: removing the phosphosilicate glass layer on the fourth region of the backlight surface; removing the N-type polysilicon layer on the fourth region; removing the phosphosilicate glass layer on the third region of the backlight surface and the tunneling oxide layer on the fourth region; sequentially forming a passivation layer and an anti-reflection layer on the N-type polysilicon layer and the fourth region in a direction away from the N-type silicon substrate; and forming a second metal electrode so that the second metal electrode passes through the anti-reflection layer and the passivation layer of the third region and contacts the N-type polysilicon layer.

[0031] According to some embodiments of the present invention, the phosphosilicate glass layer on the fourth region of the backlight surface is removed by laser; and the N-type polysilicon layer on the fourth region is removed by the alkaline solution.

[0032] According to some embodiments of the present invention, after boron diffusion, a wrap-around layer is formed on the backlight surface; before a tunneling oxide layer is formed on the backlight surface, the method further comprises: removing the wrap-around layer on the backlight surface; and polishing the backlight surface.

[0033] The third aspect of the present invention provides a photovoltaic module, comprising the TOPCon cell of the first aspect of the present invention or the TOPCon cell obtained by the method of the second aspect of the present invention. Due to the use of the TOPCon cell structure of the present invention, the photovoltaic module of the present invention has all the advantages of the TOPCon cell, which will not be repeated here.

[0034] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0036] Figure 1 It is a schematic structural diagram of the light-receiving surface of a TOPcon cell according to an embodiment of the present invention.

[0037] Figure 2 It is a schematic diagram of the structure of the TOPcon battery prepared in Example 1 of the present invention.

[0038] Figure 3-Figure 7 It is a schematic diagram of the structure obtained in each step of the preparation method provided in Example 1 of the present invention.

[0039] Reference numerals:

[0040] 2000, TOPCon cell; 100, N-type silicon substrate; 101, first region; 102, second region; 103, third region; 104, fourth region; 200, P-type emitter layer; 300, first passivation layer; 400, first anti-reflection layer; 500, first metal electrode; 600, second passivation layer; 700, second anti-reflection layer; 800, tunneling oxide layer; 900, N-type polysilicon layer; 1000, third passivation layer; 1100, third anti-reflection layer; 1200, second metal electrode; 1300, fourth passivation layer; 1400, fourth anti-reflection layer; 1500, borosilicate glass layer; 1600, phosphosilicate glass layer. DETAILED DESCRIPTION

[0041] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0042] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Further, in the description of the present invention, unless otherwise specified, "multiple" means two or more, and "multiple" means two or more.

[0043] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0044] In this document, the terms “include” or “comprising” are open expressions, that is, including the contents specified in the present invention but not excluding other contents.

[0045] TOPCon (Tunnel Oxide Passivated Contact) batteries have become mainstream battery products due to their high efficiency and low attenuation properties. How to further improve the conversion efficiency has become a bottleneck restricting its development.

[0046] In conventional TOPCon cell structures, the surface passivation performance of the boron-doped P-type emitter restricts further improvement of cell efficiency. In related technologies, the passivation performance of the P-type emitter is improved by reducing the doping concentration of the P-type emitter to reduce recombination, but at the same time, it will increase the metal contact recombination and attenuate the carrier transport performance, which is not conducive to improving the conversion efficiency of TOPCon cells.

[0047] In order to further improve the conversion efficiency of the TOPCon cell, the present invention provides an improved TOPCon cell structure, by selectively setting a P-type emitter layer on the light-receiving surface of the N-type silicon substrate, that is, setting a P-type emitter layer in the first region and not setting a P-type emitter layer in the second region, so that the carrier separation capability can be ensured and the substrate in the second region (that is, the undoped region) can be directly passivated. Since the surface recombination of the undoped region is much smaller than that of the boron-doped region, the conversion efficiency of the cell can be improved by the selective distribution of the P-type emitter layer.

[0048] Specifically, refer to Figure 1 In a first aspect, the present invention provides a TOPCon cell 2000, comprising: an N-type silicon substrate 100, the N-type silicon substrate 100 having a light-receiving surface and a backlight surface opposite to each other; the light-receiving surface comprises a first region 101 and a second region 102; a P-type emitter layer 200, a first passivation layer 300 and a first anti-reflection layer 400 are sequentially arranged on the first region 101 in a direction away from the N-type silicon substrate 100; a first metal electrode 500 is also arranged on the first region 101, the first metal electrode 500 passes through the first anti-reflection layer 400 and the first passivation layer 300 and contacts the P-type emitter layer 200; a second passivation layer 600 and a second anti-reflection layer 700 are sequentially arranged on the second region 102 in a direction away from the N-type silicon substrate 100.

[0049] In some embodiments, the first regions 101 and the second regions 102 may be alternately distributed.

[0050] In some embodiments, the area of ​​the first region 101 accounts for 40%-60% of the total area of ​​the light-receiving surface, preferably 45%-55%. The sum of the area of ​​the first region 101 and the area of ​​the second region 102 is equal to the total area of ​​the light-receiving surface. Optimizing the area ratio of the first region 101 is conducive to reducing surface recombination and improving the conversion efficiency of the battery.

[0051] In some specific embodiments, the area of ​​the first region 101 accounts for 40%, 45%, 50%, 55% or 60% of the total area of ​​the light-receiving surface.

[0052] In some embodiments, the light receiving surface may include a plurality of first regions 101 and a plurality of second regions 102. The first regions 101 and the second regions 102 may be alternately distributed. The second region 102 may be located between two adjacent first regions 101.

[0053] In some embodiments, reference Figure 2 The backlight surface includes a third region 103 and a fourth region 104. A tunneling oxide layer 800, an N-type polysilicon layer 900, a third passivation layer 1000, and a third anti-reflection layer 1100 are sequentially arranged on the third region 103 in a direction away from the N-type silicon substrate 100. A second metal electrode 1200 is also arranged on the third region 103. The second metal electrode 1200 passes through the third anti-reflection layer 1100 and the third passivation layer 1000 and contacts the N-type polysilicon layer 900. A fourth passivation layer 1300 and a fourth anti-reflection layer 1400 are sequentially arranged on the fourth region 104 in a direction away from the N-type silicon substrate 100.

[0054] The selective distribution of the N-type polysilicon layer on the backlight side ensures the thickness of the N-type polysilicon layer 900 in the third area 103 (i.e., the metal contact area), and the metallization composite is not affected. At the same time, the N-type polysilicon layer in the fourth area 104 (i.e., the non-metal contact area) is removed, which can greatly reduce parasitic absorption and improve the utilization rate of incident light, thereby improving the conversion efficiency of the battery. By simultaneously optimizing the light-receiving surface structure and the backlight surface structure, it is more conducive to improving the conversion efficiency of the battery.

[0055] In some embodiments, the third regions 103 and the fourth regions 104 may be alternately distributed.

[0056] In some embodiments, the area of ​​the third region 103 accounts for 30%-60% of the total area of ​​the backlight surface, preferably 40%-50%. The sum of the area of ​​the third region 103 and the area of ​​the fourth region 104 is equal to the total area of ​​the backlight surface. Optimizing the area ratio of the third region 103 is conducive to reducing parasitic absorption and improving the conversion efficiency of the battery.

[0057] In some specific embodiments, the area of ​​the third region 103 accounts for 30%, 35%, 40%, 45%, 50%, 55% or 60% of the total area of ​​the backlight surface.

[0058] In some embodiments, the backlight surface may include a plurality of third regions 103 and a plurality of fourth regions 104. The third regions 103 and the fourth regions 104 may be alternately distributed. The fourth region 104 may be located between two adjacent third regions 103.

[0059] In some embodiments, the thickness of the first passivation layer 300 and the second passivation layer 600 may be 2-10 nm, for example, 2 nm, 4 nm, 6 nm, 8 nm or 10 nm. The thickness of the first passivation layer 300 and the second passivation layer 600 may be the same or different. The material of the first passivation layer 300 and the second passivation layer 600 may include one or more of aluminum oxide, titanium oxide, silicon oxide, etc. The material of the first passivation layer 300 and the second passivation layer 600 may be the same or different.

[0060] In some embodiments, the thickness of the first anti-reflection layer 400 and the second anti-reflection layer 700 can be 60-100 nm, for example, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm or 100 nm. The thickness of the first anti-reflection layer 400 and the second anti-reflection layer 700 can be the same or different. The material of the first anti-reflection layer 400 and the second anti-reflection layer 700 can include one or more of silicon nitride, silicon oxide and silicon oxynitride. The material of the first anti-reflection layer 400 and the second anti-reflection layer 700 can be the same or different.

[0061] In some embodiments, the thickness of the tunneling oxide layer 800 may be 0.5 nm-2.5 nm, for example 0.5 nm, 1 nm, 1.5 nm, 2 nm or 2.5 nm. The material of the tunneling oxide layer 800 includes silicon oxide (SiOx). This layer can use the quantum tunneling effect to realize the transmission of electrons, while effectively preventing the recombination with holes, thereby achieving the purpose of passivating the backlight surface of the solar cell.

[0062] In some embodiments, the thickness of the N-type polysilicon layer 900 may be 10 nm-300 nm, such as 10 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm or 300 nm. The N-type polysilicon layer 900 may be a phosphorus-doped N-type polysilicon layer. The doping concentration of the N-type polysilicon layer 900 may be 1×10 18 cm -3 -5×10 20 cm -3 , for example 1×10 18 cm -3 , 1×10 19 cm -3 , 1×10 20 cm -3 or 5×10 20 cm -3 Optimizing the doping concentration of the N-type polysilicon layer 900 is conducive to forming a good ohmic contact between the second metal electrode 1200 and the N-type polysilicon layer 900, improving the passivation effect of the backlight surface of the battery, and thus improving the battery performance.

[0063] In some embodiments, the thickness of the third passivation layer 1000 and the fourth passivation layer 1300 may be 2nm-10nm, for example 2nm, 4nm, 6nm, 8nm or 10nm. The thickness of the third passivation layer 1000 and the fourth passivation layer 1300 may be the same or different. The material of the third passivation layer 1000 and the fourth passivation layer 1300 may include one or more of aluminum oxide, titanium oxide, silicon oxide, etc. The material of the third passivation layer 1000 and the fourth passivation layer 1300 may be the same or different.

[0064] In some embodiments, the thickness of the third anti-reflection layer 1100 and the fourth anti-reflection layer 1400 may be 60nm-100nm, for example 60nm, 65nm, 70nm, 75nm, 80nm, 85nm, 90nm, 95nm or 100nm. The thickness of the third anti-reflection layer 1100 and the fourth anti-reflection layer 1400 may be the same or different. The material of the third anti-reflection layer 1100 and the fourth anti-reflection layer 1400 may include one or more of silicon nitride and silicon oxide. The material of the third anti-reflection layer 1100 and the fourth anti-reflection layer 1400 may be the same or different.

[0065] In some embodiments, the P-type emitter layer 200 is a boron-doped P-type silicon layer. The doping concentration of the boron-doped P-type silicon layer may be 1×10 18 cm -3 -1×10 19 cm -3 , for example 1×10 18 cm -3 , 3×10 18 cm -3 , 5×10 18 cm -3 ,7×10 18 cm -3 or 1×10 19 cm -3 A good ohmic contact can be formed between the P-type emitter layer 200 and the first metal electrode 500 .

[0066] In some embodiments, the materials of the first metal electrode 500 and the second metal electrode 1200 may include one or more of silver and copper. The materials of the first metal electrode 500 and the second metal electrode 1200 may be the same or different.

[0067] The second aspect of the present invention provides a method for preparing a TOPCon battery according to the first aspect of the present invention, comprising the following steps:

[0068] Providing an N-type silicon substrate 100, wherein the N-type silicon substrate 100 has a light-receiving surface and a backlight surface opposite to each other;

[0069] A P-type emitter layer 200 is formed on the first region 101 of the light-receiving surface;

[0070] A passivation layer and an anti-reflection layer are sequentially formed on the P-type emitter layer 200 and the second region 102 of the light-receiving surface in a direction away from the N-type silicon substrate 100;

[0071] The first metal electrode 500 is formed so as to pass through the anti-reflection layer and the passivation layer of the first region 101 and contact the P-type emitter layer 200 .

[0072] The method of the present invention has the advantages of simple process scheme, low cost, etc., and the process of the present invention can be formed by making appropriate adjustments on the basis of the existing process.

[0073] In some embodiments, forming the P-type emitter layer 200 on the first region 101 of the light-receiving surface includes: forming the P-type emitter layer 200 on the entire light-receiving surface of the N-type silicon substrate 100 ; and removing the P-type emitter layer 200 on the second region 102 .

[0074] In some specific embodiments, reference Figure 3-6 , forming a P-type emitter layer 200 on the first region 101 of the light-receiving surface includes: sequentially performing texturing and boron diffusion on the light-receiving surface of the N-type silicon substrate 100, thereby forming a P-type emitter layer 200 and a borosilicate glass layer 1500; removing the borosilicate glass layer 1500 on the second region 102; removing the P-type emitter layer 200 on the second region 102 and performing secondary texturing on the second region 102; removing the borosilicate glass layer 1500 on the first region 101. In the subsequent preparation process, the borosilicate glass layer 1500 can act as a mask layer to protect the P-type emitter layer 200 on the first region 101 from being removed. The borosilicate glass layer 1500 and the P-type emitter layer 200 can be formed simultaneously, saving the step of preparing a mask layer separately and simplifying the process flow.

[0075] In some embodiments, a laser is used to remove the borosilicate glass layer 1500 on the second region 102. Laser has the characteristics of low cost, strong controllability, and short process time, and is suitable for large-scale mass production. An alkaline solution is used to remove the P-type emitter layer 200 on the second region 102 and perform secondary texturing on the second region 102. While using a wet method to remove part of the P-type emitter layer 200, the exposed silicon substrate surface can also be secondary texturing, so that the removal step and the secondary texturing step are completed at one time, simplifying the process flow. The alkaline solution includes at least one of a KOH solution and a NaOH solution. The alkaline solution contains additives. The additives include components such as surfactants, buffers and dispersants. The present invention does not specifically limit the specific types of surfactants, buffers and dispersants, and the surfactants, buffers and dispersants commonly used in the art can be used in the present invention.

[0076] In some embodiments, the borosilicate glass layer 1500 on the first region 101 is removed by wet method, for example, by etching with HF solution to remove the borosilicate glass layer 1500 on the first region 101 .

[0077] The present invention does not particularly limit the preparation method of the passivation layer on the light-receiving surface and the backlight surface, and any common method in the art can be used to prepare the passivation layer. For example, the preparation method of the passivation layer includes any one of LPCVD (low pressure chemical vapor deposition), PECVD (plasma enhanced chemical vapor deposition), and PVD (physical vapor deposition).

[0078] The present invention does not particularly limit the preparation method of the anti-reflection layer on the light-receiving surface and the backlight surface, and any common method in the art can be used to prepare the anti-reflection layer. For example, the preparation method of the anti-reflection layer includes any one of LPCVD (low pressure chemical vapor deposition), PECVD (plasma enhanced chemical vapor deposition), and PVD (physical vapor deposition).

[0079] In some embodiments, reference Figure 3-7 After forming the P-type emitter layer 200 and the borosilicate glass layer 1500 and before removing the borosilicate glass layer 1500 on the second region 102, the method further includes: sequentially forming a tunneling oxide layer 800, an N-type polysilicon layer 900 and a phosphosilicate glass layer 1600 on the backlight surface. After forming the phosphosilicate glass layer 1600, the method further includes: removing the phosphosilicate glass layer 1600 on the fourth region 104 of the backlight surface; removing the N-type polysilicon layer 900 on the fourth region 104; removing the phosphosilicate glass layer 1600 on the third region 103 of the backlight surface and the tunneling oxide layer 800 on the fourth region 104; sequentially forming a passivation layer and an anti-reflection layer on the N-type polysilicon layer 900 and the fourth region 104 in a direction away from the N-type silicon substrate 100; and forming a second metal electrode 1200, so that the second metal electrode 1200 passes through the anti-reflection layer and the passivation layer of the third region 103 and contacts the N-type polysilicon layer 900.

[0080] The selective distribution of the polysilicon layer on the backlight side is formed through the above process, and the simultaneous optimization of the light-receiving side structure and the backlight side structure is achieved, which is more conducive to improving the conversion efficiency of the battery and simplifying the process flow.

[0081] In some embodiments, the preparation of the tunneling oxide layer 800 and the N-type polysilicon layer 900 can be achieved by LPCVD or PECVD. For example, an intrinsic amorphous silicon or intrinsic polysilicon layer is first prepared on the side of the tunneling oxide layer 800 away from the N-type silicon substrate 100, and then phosphorus doping and crystallization are performed by high-temperature diffusion. In the subsequent preparation process, the phosphosilicate glass layer 1600 can act as a mask layer to protect the N-type polysilicon layer 900 and the tunneling oxide layer 800 of the third region 103 from being removed. The phosphosilicate glass layer 1600 and the N-type polysilicon layer 900 can be formed simultaneously, saving the step of preparing a mask layer separately and simplifying the process flow.

[0082] In some embodiments, a laser is used to remove the phosphosilicate glass layer 1600 on the fourth area 104 of the backlight surface. Laser has the characteristics of low cost, strong controllability, and short process time, and is suitable for large-scale mass production. This step can be performed simultaneously with the step of removing the borosilicate glass layer 1500 on the second area 102. An alkaline solution can be used to remove the N-type polysilicon layer 900 on the fourth area 104. This step can be performed wet-processed synchronously with the step of "removing the P-type emitter layer 200 on the second area 102 and performing secondary texturing on the second area 102", that is, the above steps can be completed synchronously by immersing the sample in an alkaline solution, thereby simplifying the process flow. The alkaline solution has been defined above and will not be repeated here.

[0083] In some embodiments, the phosphosilicate glass layer 1600 on the third area 103 of the backlight surface and the tunnel oxide layer 800 on the fourth area 104 are removed by wet method. For example, HF solution etching is used to remove the phosphosilicate glass layer 1600 on the third area 103 of the backlight surface and the tunnel oxide layer 800 on the fourth area 104.

[0084] In some embodiments, after the boron is diffused, a wrap-around layer is formed on the backlight surface. Before the tunnel oxide layer 800 is formed on the backlight surface, the method further includes: removing the wrap-around layer on the backlight surface; and polishing the backlight surface. Removing the wrap-around layer is beneficial to improving battery performance and yield.

[0085] In some embodiments, the first passivation layer 300 and the second passivation layer 600 are formed simultaneously. The third passivation layer 1000 and the fourth passivation layer 1300 are formed simultaneously. The first anti-reflection layer 400 and the second anti-reflection layer 700 are formed simultaneously. The third anti-reflection layer 1100 and the fourth anti-reflection layer 1400 are formed simultaneously.

[0086] The present invention does not specifically limit the preparation method of the first metal electrode 500 and the second metal electrode 1200, and any common method in the art can be used to prepare the metal electrodes. For example, the metal electrodes can be prepared by screen printing.

[0087] The scheme of the present invention will be explained below in conjunction with the embodiments. It will be appreciated by those skilled in the art that the following embodiments are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. Where specific techniques or conditions are not indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used are not indicated by the manufacturer and are all conventional products that can be obtained commercially.

[0088] Example 1

[0089] (1) Texturing: The cleaned N-type silicon substrate 100 is immersed in a sodium hydroxide aqueous solution containing a texturing auxiliary additive (purchased from Shichuang Energy Co., Ltd., model TS57v07) to form a randomly pyramidally distributed texturing surface on the front and back sides of the N-type silicon substrate 100.

[0090] (2) Boron diffusion: BCl3 is used as a boron source to deposit the boron source on the light-receiving surface of the N-type silicon substrate 100. After high-temperature advancement and oxidation, a boron-doped P-type emitter layer 200 and a borosilicate glass layer 1500 (BSG layer) are formed. The doping concentration of the emitter layer is 3×10 18 cm -3 , the junction depth is 0.8μm and the thickness of the borosilicate glass layer is 100nm.

[0091] (3) Alkali polishing: Use a 50% volume concentration HF aqueous solution to remove the BSG layer on the backlight surface, and use a NaOH aqueous solution containing a polishing auxiliary additive (purchased from Shichuang Energy Co., Ltd., model EP11v02) to remove the backlight surface and polish the backlight surface.

[0092] (4) A 1.5 nm thick tunneling silicon oxide layer 800 and a 100 nm thick intrinsic amorphous silicon layer are sequentially formed on the backlight surface by LPCVD, and then POCl3 is used as a phosphorus source to deposit a phosphorus source on the intrinsic amorphous silicon layer and oxidize it at 920°C to crystallize the intrinsic amorphous silicon layer and activate the doped phosphorus atoms to form a phosphorus-doped N-type polysilicon layer 900, and a 45 nm thick phosphorus silicon glass layer 1600 (PSG layer) is formed. The resulting structure is shown in FIG. Figure 3 shown.

[0093] (5) The BSG layer on the second light-receiving surface area 102 and the PSG layer on the fourth backlight surface area 104 are removed by laser, and the resulting structure is as follows: Figure 4 As shown, the area of ​​the first region 101 accounts for 50% of the total area of ​​the light-receiving surface, the area of ​​the second region 102 accounts for 50% of the total area of ​​the light-receiving surface, the area of ​​the third region 103 accounts for 45% of the total area of ​​the backlight surface, and the area of ​​the fourth region 104 accounts for 55% of the total area of ​​the light-receiving surface.

[0094] (6) The structure obtained in step 5 is immersed in a NaOH aqueous solution containing a texturing auxiliary additive (purchased from Shaoxing Tuobang New Energy Co., Ltd., model EP32), thereby removing the boron-doped P-type emitter layer 200 on the second light-receiving surface area 102, and performing secondary texturing on the exposed second light-receiving surface area 102, and at the same time removing the phosphorus-doped N-type polysilicon layer 900 on the fourth backlight surface area 104. The reaction of the fourth backlight surface area 104 stops at the tunneling oxide layer 800 because the alkali is less corrosive to silicon oxide. The resulting structure is as shown in FIG. Figure 5 shown.

[0095] (7) The structure obtained in step 6 is immersed in a HF aqueous solution with a volume concentration of 30%, and HF is used to remove the BSG layer on the first light-receiving surface area 101, the PSG layer on the third backlight surface area 103, and the tunneling silicon oxide layer on the fourth backlight surface area 104. The obtained structure is as shown in FIG. Figure 6 shown.

[0096] (8) A 4 nm thick aluminum oxide passivation layer is deposited on the light-receiving surface and the backlight surface of the N-type silicon substrate 100 by atomic layer deposition (ALD). Then, a composite anti-reflection layer of silicon nitride (12 nm thick), silicon oxynitride (30 nm thick) and silicon oxide (38 nm thick) with a total thickness of 80 nm is deposited on the light-receiving surface by PECVD (silicon nitride is deposited first, then silicon oxynitride is deposited, and finally silicon oxide is deposited), and a silicon nitride anti-reflection layer with a thickness of 80 nm is deposited on the backlight surface. The resulting structure is as follows: Figure 7 shown.

[0097] (9) Printing metal electrodes on the light-receiving surface and the backlight surface, and forming a first silver electrode and a second silver electrode after high-temperature sintering and laser-assisted sintering, thereby obtaining a TOPCon battery 2000. The obtained structure is as follows: Figure 2 shown.

[0098] Example 2

[0099] The TOPCon cell 2000 is prepared according to the method described in Example 1, except that the range of the laser treatment is controlled in step 5 so that the area of ​​the first region 101 accounts for 45% of the total area of ​​the light-receiving surface.

[0100] Example 3

[0101] The TOPCon cell 2000 is prepared according to the method described in Example 1, except that the range of the laser treatment is controlled in step 5 so that the area of ​​the first region 101 accounts for 55% of the total area of ​​the light-receiving surface.

[0102] Example 4

[0103] The TOPCon cell 2000 is prepared according to the method described in Example 1, except that the range of the laser treatment is controlled in step 5 so that the area of ​​the first region 101 accounts for 40% of the total area of ​​the light-receiving surface.

[0104] Example 5

[0105] The TOPCon cell 2000 is prepared according to the method described in Example 1, except that the range of the laser treatment is controlled in step 5 so that the area of ​​the first region 101 accounts for 60% of the total area of ​​the light-receiving surface.

[0106] Example 6

[0107] The TOPCon cell 2000 is prepared according to the method described in Example 1, except that the range of the laser treatment is controlled in step 5 so that the area of ​​the first region 101 accounts for 30% of the total area of ​​the light-receiving surface.

[0108] Example 7

[0109] The TOPCon cell 2000 is prepared according to the method described in Example 1, except that the range of the laser treatment is controlled in step 5 so that the area of ​​the first region 101 accounts for 70% of the total area of ​​the light-receiving surface.

[0110] Example 8

[0111] The TOPCon cell 2000 is prepared according to the method described in Example 1, except that the range of the laser treatment is controlled in step 5 so that the area of ​​the third region 103 accounts for 40% of the total area of ​​the backlight surface.

[0112] Example 9

[0113] The TOPCon cell 2000 is prepared according to the method described in Example 1, except that the range of the laser treatment is controlled in step 5 so that the area of ​​the third region 103 accounts for 50% of the total area of ​​the backlight surface.

[0114] Example 10

[0115] The TOPCon cell 2000 is prepared according to the method described in Example 1, except that the range of the laser treatment is controlled in step 5 so that the area of ​​the third region 103 accounts for 30% of the total area of ​​the backlight surface.

[0116] Embodiment 11

[0117] The TOPCon cell 2000 is prepared according to the method described in Example 1, except that the range of the laser treatment is controlled in step 5 so that the area of ​​the third region 103 accounts for 60% of the total area of ​​the backlight surface.

[0118] Example 12

[0119] The TOPCon cell 2000 is prepared according to the method described in Example 1, except that the range of the laser treatment is controlled in step 5 so that the area of ​​the third region 103 accounts for 20% of the total area of ​​the backlight surface.

[0120] Embodiment 13

[0121] The TOPCon cell 2000 is prepared according to the method described in Example 1, except that the range of the laser treatment is controlled in step 5 so that the area of ​​the third region 103 accounts for 70% of the total area of ​​the backlight surface.

[0122] Embodiment 14

[0123] The TOPCon cell 2000 was prepared according to the method described in Example 1, except that the thickness of the aluminum oxide passivation layer in step 8 was 4 nm.

[0124] Embodiment 15

[0125] The TOPCon cell 2000 was prepared according to the method described in Example 1, except that the thickness of the aluminum oxide passivation layer in step 8 was 8 nm.

[0126] Example 16

[0127] The TOPCon cell 2000 was prepared according to the method described in Example 1, except that the thickness of the aluminum oxide passivation layer in step 8 was 2 nm.

[0128] Embodiment 17

[0129] The TOPCon cell 2000 was prepared according to the method described in Example 1, except that the thickness of the aluminum oxide passivation layer in step 8 was 10 nm.

[0130] Embodiment 18

[0131] A TOPCon cell is prepared according to the method described in Example 1, except that in step 5, laser is not used to remove the PSG layer on the fourth area 104 of the backlight surface, and the PSG layer on the fourth area 104 of the backlight surface is completely retained. The backlight surface of the final cell does not have a selective distribution of the N-type polysilicon layer, and the area of ​​the third area 103 accounts for 100% of the total area of ​​the backlight surface.

[0132] Comparative Example 1

[0133] A TOPCon cell was prepared according to the method described in Example 1, except that steps 5 and 6 were not performed, and the light-receiving side of the final cell did not have a selective distribution of the P-type emitter layer, and the backlight side did not have a selective distribution of the N-type polysilicon layer.

[0134] Battery performance test

[0135] Photoelectric conversion efficiency test of the battery: The battery was tested by IV under standard conditions using FCT-650 equipment. The test results are shown in Table 1 below.

[0136] Table 1

[0137]

[0138]

[0139] By comparing Examples 1-18 and Comparative Example 1, it can be seen that by selectively setting a P-type emitter layer on the light-receiving surface of the N-type silicon substrate, that is, setting a P-type emitter layer in the first region and not setting a P-type emitter layer in the second region, it is possible to ensure the carrier separation capability and directly passivate the substrate in the second region (i.e., the undoped region). Since the surface recombination of the undoped region is much smaller than that of the boron-doped region, the photoelectric conversion efficiency of the battery can be improved through the selective distribution of the P-type emitter layer.

[0140] Comparing Example 1 with Examples 2-7, it can be seen that the area ratio of the first region to the light-receiving surface affects the photoelectric conversion efficiency of the battery.

[0141] Comparing Example 1 with Examples 8-13, it can be seen that the area ratio of the third region on the backlight surface affects the photoelectric conversion efficiency of the battery.

[0142] By comparing Example 1 with Examples 14-17, it can be seen that the thickness of the passivation layer affects the photoelectric conversion efficiency of the battery. When the passivation layer is thin, it cannot form a good passivation effect on the surface, and surface recombination will reduce the photoelectric conversion efficiency of the battery; when the passivation layer is thick, the contact performance between the metal electrode and silicon will deteriorate, which is not conducive to forming a good ohmic contact, resulting in a low photoelectric conversion efficiency.

[0143] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0144] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A TOPCon battery, characterized in that: include: An N-type silicon substrate having a light-receiving surface and a backlight surface opposite to each other; the light-receiving surface includes a first region and a second region; A P-type emitter layer, a first passivation layer, and a first anti-reflection layer are sequentially arranged on the first region in a direction away from the N-type silicon substrate; a first metal electrode is also arranged on the first region, the first metal electrode passes through the first anti-reflection layer and the first passivation layer and contacts the P-type emitter layer; A second passivation layer and a second anti-reflection layer are sequentially disposed on the second region in a direction away from the N-type silicon substrate.

2. The TOPCon battery according to claim 1, characterized in that The area of ​​the first region accounts for 40%-60%, preferably 45%-55% of the total area of ​​the light-receiving surface.

3. The TOPCon battery according to claim 1 or 2, characterized in that: The backlight surface includes a third area and a fourth area; A tunneling oxide layer, an N-type polysilicon layer, a third passivation layer and a third anti-reflection layer are sequentially arranged on the third region in a direction away from the N-type silicon substrate; a second metal electrode is also arranged on the third region, the second metal electrode passes through the third anti-reflection layer and the third passivation layer and contacts the N-type polysilicon layer; A fourth passivation layer and a fourth anti-reflection layer are sequentially arranged on the fourth region in a direction away from the N-type silicon substrate.

4. The TOPCon battery according to claim 3, characterized in that The area of ​​the third region accounts for 30%-60%, preferably 40%-50% of the total area of ​​the backlight surface.

5. The TOPCon battery according to claim 3, characterized in that: The TOPCon battery meets at least one of the following conditions: (1) The thickness of the first passivation layer and the second passivation layer are both 2nm-10nm; (2) The thickness of the first anti-reflection layer and the second anti-reflection layer are both 60nm-100nm; (3) The thickness of the tunnel oxide layer is 0.5 nm to 2.5 nm; (4) The thickness of the N-type polysilicon layer is 10 nm to 300 nm; (5) The thickness of the third passivation layer and the fourth passivation layer are both 2nm-10nm; (6) The thickness of the third anti-reflection layer and the fourth anti-reflection layer are both 60nm-100nm; (7) The P-type emitter layer is a boron-doped P-type emitter layer; (8) The N-type polysilicon layer is a phosphorus-doped N-type polysilicon layer.

6. A method for preparing the TOPCon battery according to any one of claims 1 to 5, characterized in that: The following steps are involved: Providing an N-type silicon substrate, wherein the N-type silicon substrate has a light-receiving surface and a backlight surface opposite to each other; forming a P-type emitter layer on the first region of the light-receiving surface; forming a passivation layer and an anti-reflection layer in sequence on the P-type emitter layer and the second region of the light-receiving surface in a direction away from the N-type silicon substrate; A first metal electrode is formed so that the first metal electrode passes through the anti-reflection layer and the passivation layer in the first region and contacts the P-type emitter layer.

7. The method according to claim 6, characterized in that Forming a P-type emitter layer on the first region of the light-receiving surface includes: forming a P-type emitter layer on the entire light-receiving surface of the N-type silicon substrate; and removing the P-type emitter layer on the second region.

8. The method according to claim 7, characterized in that Forming a P-type emitter layer on the first region of the light-receiving surface comprises: performing texturing and boron diffusion on the light-receiving surface of the N-type silicon substrate in sequence, thereby forming a P-type emitter layer and a borosilicate glass layer; removing the borosilicate glass layer on the second area; removing the P-type emitter layer on the second region and performing secondary texturing on the second region; The borosilicate glass layer on the first region is removed.

9. The method according to claim 8, characterized in that removing the borosilicate glass layer on the second area by using laser; Using an alkaline solution to remove the P-type emitter layer on the second region and performing secondary texturing on the second region; The alkaline solution includes at least one of a KOH solution and a NaOH solution.

10. The method according to claim 9, characterized in that After forming the P-type emitter layer and the borosilicate glass layer and before removing the borosilicate glass layer on the second region, the method further comprises: sequentially forming a tunneling oxide layer, an N-type polysilicon layer and a phosphosilicate glass layer on the backlight surface; After forming the phosphosilicate glass layer, the method further includes: removing the phosphosilicate glass layer on the fourth area of ​​the backlight surface; removing the N-type polysilicon layer on the fourth area; removing the phosphosilicate glass layer on the third area of ​​the backlight surface and the tunneling oxide layer on the fourth area; forming a passivation layer and an anti-reflection layer on the N-type polysilicon layer and the fourth area in sequence in a direction away from the N-type silicon substrate; and forming a second metal electrode so that the second metal electrode passes through the anti-reflection layer and the passivation layer of the third area and contacts the N-type polysilicon layer.

11. The method according to claim 10, characterized in that Using laser to remove the phosphorus-silicate glass layer on the fourth area of ​​the backlight surface; The N-type polysilicon layer on the fourth region is removed using the alkaline solution.

12. The method according to claim 10, characterized in that After the boron is diffused, a wrap-around layer is formed on the backlight surface; before a tunneling oxide layer is formed on the backlight surface, the method further comprises: removing the wrap-around layer on the backlight surface; and polishing the backlight surface.

13. A photovoltaic module, characterized in that: A TOPCon battery comprising the TOPCon battery according to any one of claims 1 to 5 or a TOPCon battery obtained by the method according to any one of claims 6 to 12.

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