TOPCon battery, photovoltaic module and laminated battery

Abstract

The utility model is suitable for the technical field of solar power generation, and provides a TOPCon cell, a photovoltaic assembly and a laminated cell, the TOPCon cell comprises a silicon substrate, a P + layer, at least one layer of front passivation contact structure, a front metal electrode, at least one layer of back passivation contact structure and a back metal electrode, the at least one layer of front passivation contact structure and the P + layer are arranged on the front surface of the silicon substrate, the front passivation contact structure comprises a first silicon oxide layer and a first doping layer, the front metal electrode is connected with the first doping layer, the back passivation contact structure comprises a second silicon oxide layer and a second doping layer, and the back metal electrode is connected with the second doping layer. Through the arrangement, the front metal electrode does not need to be in direct contact with the p + layer, the front contact recombination is reduced, the cell conversion efficiency is improved, meanwhile, the front passivation contact structure can be directly prepared on the P + layer, the front does not need a mask, the front passivation contact structure and the back passivation contact structure can be formed in one step, the preparation process is simplified, and the preparation efficiency is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of solar power generation, and in particular relates to a TOPCon battery, a photovoltaic component and a laminated battery. Background Art

[0002] TOPCon (Tunnel Oxide Passivating Contact) cells are tunnel oxide passivating contact solar cells with silicon substrate as the substrate. TOPCon cells use tunnel oxide (tunnel oxide) with excellent charge transfer properties as the charge transfer layer on the back of the cell, and then deposit a thin layer of doped polysilicon to form a back passivation contact structure, which can effectively reduce surface recombination and metal contact recombination, increase the opening voltage, and improve the energy conversion efficiency.

[0003] The existing TOPCon cell first undergoes boron diffusion to form a high surface concentration p+ layer and BSG (Back Surface Field Silicon Wafer, back surface field silicon wafer), removes the back p+ layer and BSG, and then performs subsequent SiOx / poly-Si deposition and phosphorus diffusion, removes BSG / PSG, and then performs RCA cleaning, and then deposits the front and back passivation films, and screen prints the grid lines, thereby preparing a TOPCon cell. The cell structure is as follows Figure 1 However, the metal grid line on the front side of the existing TOPCon cell is in direct contact with the p+ layer, which causes serious contact recombination of the cell and reduces the cell conversion efficiency. Utility Model Content

[0004] The embodiments of the utility model provide a TOPCon cell, a photovoltaic module and a stacked cell, aiming to solve the problems of serious contact recombination and low cell conversion efficiency of the existing TOPCon cells.

[0005] The embodiment of the utility model is implemented as follows: a TOPCon cell includes a silicon substrate, a P+ layer, at least one front passivation contact structure, a front metal electrode, at least one back passivation contact structure and a back metal electrode;

[0006] The P+ layer is disposed on the front side of the silicon substrate;

[0007] At least one front passivation contact structure stack is disposed on the P+ layer, the front passivation contact structure comprising a first silicon oxide layer and a first doping layer sequentially disposed in a direction away from the silicon substrate;

[0008] The front metal electrode is connected to the first doped layer;

[0009] At least one back passivation contact structure is stacked on the back of the silicon substrate. The back passivation contact structure includes a second silicon oxide layer and a second doped layer sequentially arranged in a direction away from the silicon substrate. The back metal electrode is connected to the second doped layer.

[0010] Furthermore, a P+ layer is provided in a local area of ​​the front side.

[0011] Furthermore, the width of the P+ layer is 20 micrometers to 2000 micrometers.

[0012] Furthermore, at least two P+ layers are arranged on the front side, and the distance between two adjacent P+ layers is 100 micrometers to 5000 micrometers.

[0013] Furthermore, the edge of the front passivation contact structure is directly opposite to or staggered from the edge of the P+ layer.

[0014] Furthermore, the width of the P+ layer is smaller than the width of the front passivation contact structure.

[0015] Furthermore, the TOPCon battery also includes a front passivation film, which is arranged on a side of the first doped layer away from the first silicon oxide layer, and the front metal electrode passes through the front passivation film and is connected to the first doped layer.

[0016] Furthermore, the TOPCon cell also includes a back passivation film, which is arranged on a side of the second doped layer away from the second silicon oxide layer, and the back metal electrode passes through the back passivation film and is connected to the second doped layer.

[0017] Further, the front passivation film and the back passivation film include at least one of silicon nitride, aluminum oxide, silicon oxynitride and silicon oxide.

[0018] Furthermore, the front surface and / or the back surface is a polished surface or a velvet surface.

[0019] Furthermore, the first doped layer and the second doped layer are both N-type doped polysilicon layers.

[0020] In a second aspect, the present application also provides a photovoltaic module, comprising the TOPCon cell as described above.

[0021] In a third aspect, the present application also provides a stacked battery, including a perovskite battery and a TOPCon battery as described above.

[0022] The beneficial effect of the present application is that the TOPCon battery of the present application includes a silicon substrate, a P+ layer, at least one front passivation contact structure, a front metal electrode, at least one back passivation contact structure and a back metal electrode, the P+ layer is arranged on the front of the silicon substrate, at least one front passivation contact structure is stacked on the P+ layer, the front passivation contact structure includes a first silicon oxide layer and a first doping layer sequentially arranged in a direction from the silicon substrate to away from the silicon substrate, the front metal electrode is connected to the first doping layer, at least one back passivation contact structure is stacked on the back of the silicon substrate, the back passivation contact structure includes a second silicon oxide layer and a second doping layer sequentially arranged in a direction from the silicon substrate to away from the silicon substrate, and the back metal electrode is connected to the second doping layer. Through the above arrangement, a front passivation contact structure plus a p+ layer is prepared on the front of the silicon substrate, the front metal electrode does not need to be in direct contact with the p+ layer, the front contact recombination is reduced, and the battery conversion efficiency is improved. At the same time, since the first doping layer in the front passivation contact structure and the second doping layer in the back passivation contact structure have the same doping polarity, they can be formed in one step, simplifying the preparation process and improving the preparation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the structure of the existing TOPCon battery;

[0024] Figure 2 It is a structural schematic diagram of an embodiment of a TOPCon battery provided in the present application;

[0025] Figure 3 It is a structural schematic diagram of the local arrangement of the P+ layer of an embodiment of the TOPCon battery provided in the present application. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. Examples of embodiments are shown in the accompanying drawings, in which the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the utility model, and cannot be understood as limiting the utility model. In addition, it should be understood that the specific embodiments described herein are only used to explain the utility model and are not used to limit the utility model.

[0027] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present invention.

[0028] In addition, 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 technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of the present utility model, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0029] In the description of the present utility model, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" 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, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0030] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0031] The disclosure below provides many different embodiments or examples for realizing different structures of the utility model. In order to simplify the disclosure of the utility model, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the utility model. In addition, the utility model can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, and does not indicate the relationship between the various embodiments and / or settings discussed in itself. In addition, the utility model provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0032] The TOPCon cell of the present application includes a silicon substrate, a P+ layer, at least one front passivation contact structure, a front metal electrode, at least one back passivation contact structure and a back metal electrode, the P+ layer is arranged on the front of the silicon substrate, at least one front passivation contact structure is stacked on the P+ layer, the front passivation contact structure includes a first silicon oxide layer and a first doping layer sequentially arranged in a direction from the silicon substrate to away from the silicon substrate, the front metal electrode is connected to the first doping layer, at least one back passivation contact structure is stacked on the back of the silicon substrate, the back passivation contact structure includes a second silicon oxide layer and a second doping layer sequentially arranged in a direction from the silicon substrate to away from the silicon substrate, and the back metal electrode is connected to the second doping layer. Through the above arrangement, a front passivation contact structure plus a p+ layer is prepared on the front of the silicon substrate, the front metal electrode does not need to be in direct contact with the p+ layer, the front contact recombination is reduced, and the battery conversion efficiency is improved. At the same time, since the first doping layer in the front passivation contact structure and the second doping layer in the back passivation contact structure have the same doping polarity, they can be formed in one step, simplifying the preparation process and improving the preparation efficiency.

[0033] Embodiment 1

[0034] like Figures 2 to 3 As shown, one embodiment of the present application provides a TOPCon cell, comprising a silicon substrate 100, a P+ layer 200, at least one front passivation contact structure 300, a front metal electrode 400, a back passivation contact structure 500 and a back metal electrode 600;

[0035] The P+ layer 200 is disposed on the front surface of the silicon substrate 100;

[0036] At least one layer of front passivation contact structure 300 is stacked on the P+ layer 200, and the front passivation contact structure 300 includes a first silicon oxide layer 310 and a first doping layer 320 sequentially arranged in a direction away from the silicon substrate 100; in this embodiment, the first doping layer 320 is an N-type doped polysilicon layer;

[0037] The front metal electrode 400 is connected to the first doped layer 320;

[0038] At least one layer of back passivation contact structure 500 is stacked on the back side of the silicon substrate 100, and the back passivation contact structure 500 includes a second silicon oxide layer 510 and a second doped layer 520 arranged in sequence along the direction from the silicon substrate 100 to away from the silicon substrate 100. In this embodiment, the second doped layer 520 is an N-type doped polysilicon layer; the back metal electrode 600 is connected to the second doped layer 520.

[0039] In implementation, the silicon substrate 100 can be an N-type silicon wafer or a P-type silicon wafer, wherein the N-type silicon wafer is obtained by adding a pentavalent element (such as phosphorus) to the intrinsic semiconductor silicon, and the P-type silicon wafer is obtained by adding a trivalent element (such as boron, gallium or indium) to the intrinsic semiconductor silicon, which will not be described in detail. The silicon substrate 100 has a front side and a back side, wherein the front side of the silicon substrate 100 corresponds to the light-receiving side of the solar cell, and similarly, the back side of the silicon substrate 100 corresponds to the backlight side of the solar cell.

[0040] A P+ layer 200 is disposed on the front side of the silicon substrate 100 . The P+ layer 200 is generated by diffusing boron on the silicon substrate 100 . That is, the P+ layer 200 is a P-type silicon layer generated by doping the silicon substrate 100 with boron.

[0041] After the boron diffusion process is performed on the silicon substrate 100, a P+ layer 200 and a BSG (Back Surface Field Silicon Wafer) layer may be generated on the front side of the silicon substrate 100, or a P+ layer 200 and a PSG (Phosphorus-doped Silicon Wafer) layer may be generated on the front side of the silicon substrate 100. Before performing subsequent processes, it is necessary to remove the BSG or PSG on the front side and retain the P+ layer 200.

[0042] In some embodiments, the BSG or PSG on the front side can be removed by etching, for example, the silicon substrate 100 after boron diffusion is placed in an etching solution to remove the BSG or PSG on the front side. The etching solution can be an aqueous solution of H2SO4 (sulfuric acid) plus HF (hydrofluoric acid) or a solution that can etch BSG or PSG, without limitation.

[0043] In some possible embodiments, in order to prevent the etching solution from causing damage to the back side and / or side of the silicon substrate 100, the back side and / or side of the silicon substrate 100 after boron diffusion can be first covered with a layer of water film, and then the silicon substrate 100 covered with the water film is placed in the etching solution to remove BSG or PSG.

[0044] At least one layer of front passivation contact structure 300 is further disposed on the P+ layer 200 . These front passivation contact structures 300 are stacked on the P+ layer 200 layer by layer in a stacked manner.

[0045] The front passivation contact structure 300 is a passivation contact structure arranged on the front side of the battery, and the passivation contact structure includes a first silicon oxide layer 310 and a first doping layer 320, wherein the first silicon oxide layer 310 refers to a tunneling oxide layer (SiO2), and the first doping layer 320 refers to a doped polysilicon layer (n-poly).

[0046] During implementation, the first silicon oxide layer 310 and the first doping layer 320 may be prepared by PECVD (plasma enhanced chemical vapor deposition) or LPCVD (Low Pressure Chemical Vapor Deposition), without limitation.

[0047] Optionally, the passivation contact structure may have only one layer, that is, a first silicon oxide layer 310 and a first doping layer 320 are disposed on the P+ layer 200, such as Figure 2 or Figure 3 shown.

[0048] Optionally, the passivation contact structure may be provided with multiple layers, such as 2 layers, 3 layers, 4 layers or other number of layers, without limitation. Exemplarily, taking the passivation contact structure including 2 layers as an example, that is, a first silicon oxide layer 310, a first doping layer 320, a first silicon oxide layer 310 and a first doping layer 320 are sequentially provided on the P+ layer 200, that is, a P+ layer 200 / SiOx / n-poly / SiOx / n-poly structure; Optionally, taking the passivation contact structure including 3 layers as an example, that is, a first silicon oxide layer 310, a first doping layer 320, a first silicon oxide layer 310, a first doping layer 320, a first silicon oxide layer 310 and a first doping layer 320 are sequentially provided on the P+ layer 200, that is, a P+ layer 200 / SiOx / n-poly / SiOx / n-poly / SiOx / n-poly structure, which will not be described in detail.

[0049] In implementation, when there is only one layer of passivation contact structure, the front metal electrode 400 is directly connected to the first doped layer 320. At this time, the front metal electrode 400 and the P+ layer 200 are indirectly connected through a layer of passivation contact structure, that is, the front metal electrode 400 and the P+ layer 200 are prevented from directly contacting, reducing the front contact recombination and improving the battery conversion efficiency. When the passivation contact structure is provided with multiple layers, these passivation contact structures are passivation contact structures of the same polarity, wherein, except for the passivation contact structure closest to the silicon substrate 100, the other passivation contact structures are provided with perforations (not shown in the figure), and the front metal electrode 400 passes through the perforations and contacts the first doped layer 320 of the passivation contact structure closest to the silicon substrate 100, so that the front metal electrode 400 and the P+ layer 200 are in indirect contact, reducing the front contact recombination and improving the battery conversion efficiency. Of course, in some possible embodiments, when the passivation contact structure is provided with multiple layers, only part of the passivation contact structure may be provided with perforations. For example, a first passivation contact structure, a second passivation contact structure and a third passivation contact structure are provided in sequence along a direction away from the silicon substrate 100, wherein only the third passivation contact structure is provided with perforations. At this time, the front metal electrode 400 contacts the first doping layer 320 of the second passivation contact structure after passing through the perforations, thereby reducing the front contact recombination and improving the battery conversion efficiency.

[0050] Optionally, the through-holes of the passivation contact structure may be formed by burning through molten metal paste. For example, the front metal electrode 400 is formed after the molten metal paste is cooled and solidified, which will not be described in detail.

[0051] At least one layer of back passivation contact structure 500 and back metal electrode 600 is disposed on the back side of silicon substrate 100. In implementation, back passivation contact structure 500 and back metal electrode 600 can refer to the front passivation contact structure 300 and front metal electrode 400 described above, and no further description is given. Optionally, the front passivation contact structure 300 and the back passivation contact structure 500 have the same polarity, and the front passivation contact structure 300 and the back passivation contact structure 500 can be prepared step by step or simultaneously, without setting a mask, thereby simplifying the preparation process.

[0052] The TOPCon cell of the present application includes a silicon substrate 100, a P+ layer 200, at least one front passivation contact structure 300, a front metal electrode 400, at least one back passivation contact structure 500 and a back metal electrode 600. The P+ layer 200 is arranged on the front side of the silicon substrate 100, and at least one front passivation contact structure 300 is stacked on the P+ layer 200. The front passivation contact structure 300 includes a first silicon oxide layer 310 and a first doped layer 320 sequentially arranged in a direction from the silicon substrate 100 to away from the silicon substrate 100. The front metal electrode 400 is connected to the first doped layer 320. At least one back passivation contact structure 500 is stacked on the back side of the silicon substrate 100. The back passivation contact structure 500 includes a second silicon oxide layer 510 and a second doped layer 520 sequentially arranged in a direction from the silicon substrate 100 to away from the silicon substrate 100, and the back metal electrode 600 is connected to the second doped layer 520. Through the above arrangement, a front passivation contact structure 300 is prepared on the front side of the silicon substrate 100, and the front metal electrode 400 does not need to be in direct contact with the p+ layer 200, thereby reducing the front contact recombination and improving the battery conversion efficiency. At the same time, the front passivation contact structure 300 can be directly prepared on the p+ layer 200, and no mask is required on the front side. Moreover, the front passivation contact structure 300 and the back passivation contact structure 500, and at the same time, since the first doping layer 320 in the front passivation contact structure 300 and the second doping layer 520 in the back passivation contact structure 500 have the same doping polarity, they can be formed in one step, thereby simplifying the preparation process and improving the preparation efficiency.

[0053] In some optional embodiments, the P+ layer 200 is disposed in a local area of ​​the front side.

[0054] In implementation, the p+ layer 200 can be full surface or regional contact, that is, the p+ layer 200 can be arranged on the entire front surface of the silicon substrate 100, or can be arranged on a partial area of ​​the front surface of the silicon substrate 100, and the width of the p+ layer 200 is 20 microns-2000 microns, for example, the width of the p+ layer 200 is 30 microns, 100 microns, 500 microns or 1000 microns, etc., without limitation, and the p+ layer 200 is arranged below the front passivation contact structure 300. Through such a setting, the surface recombination of the non-contact area can be effectively reduced, and the battery conversion efficiency can be improved.

[0055] In some optional embodiments, when the P+ layer 200 is arranged in a local area of ​​the front side, at least two P+ layers 200 may be arranged, and the distance between two adjacent P+ layers 200 is 100 microns-5000 microns. For example, the distance between two adjacent P+ layers 200 is 200 microns, 500 microns, 1000 microns, 2000 microns or 4000 microns, etc., without limitation.

[0056] In some optional embodiments, the edge of the front passivation contact structure 300 is opposite to or staggered with the edge of the P+ layer 200, wherein one side edge of the front passivation contact structure 300 may be opposite to or staggered with one side edge of the P+ layer 200, and similarly, the other side edge of the front passivation contact structure 300 may be opposite to or staggered with the other side edge of the P+ layer 200. Exemplarily, when each edge of the front passivation contact structure 300 is opposite to the edge of the P+ layer 200, the shape and size of the front passivation contact structure 300 and the P+ layer 200 are the same.

[0057] In other embodiments, when any edge of the front passivation contact structure 300 is misaligned with the edge of the P+ layer 200, it indicates that the front passivation contact structure 300 and the P+ layer 200 are not completely the same. For example, the front passivation contact structure 300 can be arranged in a local area of ​​the P+ layer 200, that is, the front passivation contact structure 300 is smaller than the P+ layer 200. Through the above arrangement, contact recombination can be effectively reduced.

[0058] In some possible embodiments, the width of the P+ layer 200 is smaller than that of the front passivation contact structure 300. Through the above configuration, the width of the P+ layer 200 is smaller, thereby reducing contact recombination.

[0059] In some optional embodiments, the TOPCon battery provided in the present application further includes a front passivation film 700 , which is disposed on a side of the first doping layer 320 away from the first silicon oxide layer 310 , and the front metal electrode 400 is connected to the first doping layer 320 through the front passivation film 700 .

[0060] The front passivation film 700 is a passivation film, which is used to improve the photoelectric conversion efficiency and stability of the solar cell, reduce surface damage and oxidation reaction of the solar cell, and extend the service life of the solar cell.

[0061] Optionally, the front passivation film 700 may be provided with an opening, and the front metal electrode 400 passes through the opening of the front passivation film 700 and is connected to the first doping layer 320. In other possible embodiments, the front metal electrode 400 is not provided with an opening, and is connected to the first doping layer 320 after the molten metal slurry burns through the front passivation film 700, and the metal slurry is cooled and solidified to form the front metal electrode 400.

[0062] In some optional embodiments, the TOPCon cell provided in the present application further includes a back passivation film 800, which is disposed on a side of the second doping layer 520 away from the second silicon oxide layer 510, and the back metal electrode 600 passes through the back passivation film 800 and is connected to the second doping layer 520. The back passivation film 800 can refer to the front passivation film 700 described above, and no further description is given.

[0063] In some possible embodiments, the passivation film includes at least one of silicon nitride, aluminum oxide, silicon oxynitride and silicon oxide, etc., without limitation. Preferably, the front passivation film 700 and / or the back passivation film 800 can be made of aluminum oxide to ensure light absorption rate.

[0064] In some optional embodiments, the front and / or back of the silicon substrate 100 is a polished surface or a velvet surface. Generally, before the silicon substrate 100 is subjected to the boron diffusion process, the silicon substrate 100 may be polished or velvet-treated. Among them, the polishing process of the silicon substrate 100 may be performed by mechanical polishing, chemical mechanical polishing, electrochemical polishing, photocatalytic assisted chemical mechanical polishing, etc., in order to enhance the polishing effect, improve the surface roughness of the silicon substrate 100, and increase the material removal rate. The velvet treatment refers to the use of a specific process (such as a chemical wet process) to process the front and / or back of the silicon substrate 100 to form a pyramid-shaped velvet surface on the front and / or back. The light trapping principle of the velvet surface is used. When light is incident on a slope at a certain angle, the light will be reflected to a slope at another angle, forming secondary or multiple absorption, thereby increasing the absorption rate, reducing the reflectivity of light, and increasing the short-circuit current, thereby improving the photoelectric conversion efficiency.

[0065] In some embodiments, taking a front passivation contact structure 300 and a back passivation contact structure 500 as an example, the preparation process of the TOPCon cell provided in the present application includes the following steps:

[0066] Step 1, cleaning the silicon substrate 100, and then performing texturing or polishing on the silicon substrate 100;

[0067] Step 2: performing boron diffusion on the silicon substrate 100 to generate a P+ layer 200 and BSG on both the front and back sides of the silicon substrate 100;

[0068] Step 3, removing the back p+ layer 200 and the front and back BSG;

[0069] Step 4: Perform high-temperature n-poly process on the front and back sides to form SiOx / n-poly passivation contact on the back side and n-poly / SiOx / p+ layer tunnel junction passivation contact on the front side;

[0070] During implementation, the front passivation contact structure 300 can be generated on the P+ layer 200 while performing the high-temperature n-poly process on the back side, without the need to use a mask, thereby reducing the process flow and controlling costs. In addition, the front n-poly process and the back n-poly process can be performed simultaneously or separately. Preferably, the front n-poly process and the back n-poly process can be performed simultaneously, that is, the front passivation contact structure 300 and the back passivation contact structure 500 can be prepared and generated in one step, further simplifying the preparation process.

[0071] Step 5, remove BSG / PSG and then perform RCA cleaning;

[0072] When implemented, the RCA cleaning method mainly includes two steps:

[0073] SC1 cleaning: This is an alkaline solution, the main purpose of which is to remove particles, metals and organic matter. Through the strong oxidizing effect of hydrogen peroxide and the alkaline corrosion effect of ammonium hydroxide, particles and organic pollutants on the surface of silicon wafers can be effectively removed.

[0074] SC2 cleaning: This is an acidic solution, the main function of which is to remove metal ions. The metal impurities on the surface of the wafer can be removed through the oxidation of hydrogen peroxide and the acid corrosion of hydrochloric acid.

[0075] In addition, the RCA cleaning method also includes several other cleaning solutions, such as a mixture of H2SO4+H2O2 (sulfuric acid plus hydrogen peroxide) for removing metals and organic matter, and diluted hydrofluoric acid for removing oxide films on the surface of silicon wafers. The order and conditions of using these cleaning solutions are selected according to specific cleaning requirements and material properties, and are not limited.

[0076] In order to improve the effect of RCA cleaning, it can also be combined with megasonic cleaning technology. Megasonic cleaning uses high-frequency sound waves in liquid media to generate tiny cavitation bubbles. When these bubbles burst, local shock waves are generated, thereby effectively removing pollutants on the surface of silicon wafers. The above combined method can ensure the cleanliness of silicon wafers.

[0077] Step 6: Deposit the front and back passivation films and screen-print the grid lines (front metal electrode 400 and back metal electrode 600), thereby preparing a TOPCon cell with low surface recombination.

[0078] In some possible embodiments, light injection and laser enhanced contact processing can be performed after screen printing and grid line sintering. After the light injection, laser irradiation and reverse bias current are applied simultaneously to optimize the paste contact.

[0079] In some possible embodiments, taking the local setting of the P+ layer 200 as an example, the preparation process of the TOPCon battery provided in the present application includes the following steps:

[0080] Step 1: Clean the silicon substrate 100, which is a P-type silicon wafer, and then perform texturing or polishing on the silicon substrate 100;

[0081] Step 2: performing boron diffusion on the silicon substrate 100 to generate a P+ layer 200 and BSG on both the front and back sides of the silicon substrate 100;

[0082] Step 3, removing the back p+ layer 200 and the front and back BSG;

[0083] Step 4: Perform high-temperature n-poly process on the front and back sides to form SiOx / n-poly passivation contact on the back side and n-poly / SiOx / P+ layer tunnel junction passivation contact on the front side;

[0084] Step 5: Pattern the front n-poly / SiOx / P+ layer, retain the n-poly / SiOx / P+ layer structure under the gate line (front metal electrode 400), remove BSG / PSG and then perform RCA cleaning;

[0085] The high-temperature n-poly process and RCA cleaning of the front and back surfaces refer to the process and principle of the above-mentioned embodiment and will not be described in detail.

[0086] Step 6: Deposit the front and back passivation films and screen-print the grid lines (front metal electrode 400 and back metal electrode 600), thereby preparing a TOPCon cell with low surface recombination.

[0087] In some possible embodiments, light injection and laser enhanced contact processing can be performed after screen printing and grid line sintering.

[0088] Embodiment 2

[0089] In some optional embodiments, the present application provides a photovoltaic module, comprising the TOPCon cell as described above.

[0090] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the structure and implementation principle of the photovoltaic assembly described above can refer to the corresponding structure and implementation principle in the aforementioned embodiment 1, and will not be repeated here.

[0091] The TOPCon cell of the present application includes a silicon substrate 100, a P+ layer 200, at least one front passivation contact structure 300, a front metal electrode 400, at least one back passivation contact structure 500 and a back metal electrode 600. The P+ layer 200 is arranged on the front side of the silicon substrate 100, and at least one front passivation contact structure 300 is stacked on the P+ layer 200. The front passivation contact structure 300 includes a first silicon oxide layer 310 and a first doped layer 320 sequentially arranged in a direction from the silicon substrate 100 to away from the silicon substrate 100. The front metal electrode 400 is connected to the first doped layer 320. At least one back passivation contact structure 500 is stacked on the back side of the silicon substrate 100. The back passivation contact structure 500 includes a second silicon oxide layer 510 and a second doped layer 520 sequentially arranged in a direction from the silicon substrate 100 to away from the silicon substrate 100, and the back metal electrode 600 is connected to the second doped layer 520. Through the above arrangement, a front passivation contact structure 300 is prepared on the front side of the silicon substrate 100, and the front metal electrode 400 does not need to be in direct contact with the p+ layer 200, thereby reducing the front contact recombination and improving the battery conversion efficiency. At the same time, the front passivation contact structure 300 can be directly prepared on the p+ layer 200, and no mask is required on the front side. Moreover, the front passivation contact structure 300 and the back passivation contact structure 500, and at the same time, since the first doping layer 320 in the front passivation contact structure 300 and the second doping layer 520 in the back passivation contact structure 500 have the same doping polarity, they can be formed in one step, thereby simplifying the preparation process and improving the preparation efficiency.

[0092] Embodiment 3

[0093] In some optional embodiments, the present application also provides a stacked battery, including a perovskite battery and a TOPCon battery as described above.

[0094] In practice, perovskite cells, i.e., perovskite solar cells, are solar cells that use perovskite-type organic metal halide semiconductors as light-absorbing materials. The tandem cells provided in this application are perovskite-silicon-based tandem solar cells. Perovskite-silicon-based tandem cells utilize the wide bandgap structural characteristics of perovskite cell materials, and place perovskite cell materials above silicon-based cells, which can absorb high-energy photons in the short-wave band that are difficult for silicon-based cells to absorb, thereby making greater use of solar incident light, thereby improving the conversion efficiency of photovoltaic cells, and having a higher theoretical efficiency limit, which will not be elaborated on.

[0095] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, the structure and implementation principle of the laminated battery described above can refer to the corresponding structure and implementation principle in the aforementioned embodiments 1 and 2, and will not be repeated here.

[0096] The TOPCon cell of the present application includes a silicon substrate 100, a P+ layer 200, at least one front passivation contact structure 300, a front metal electrode 400, at least one back passivation contact structure 500 and a back metal electrode 600. The P+ layer 200 is arranged on the front side of the silicon substrate 100, and at least one front passivation contact structure 300 is stacked on the P+ layer 200. The front passivation contact structure 300 includes a first silicon oxide layer 310 and a first doped layer 320 sequentially arranged in a direction from the silicon substrate 100 to away from the silicon substrate 100. The front metal electrode 400 is connected to the first doped layer 320. At least one back passivation contact structure 500 is stacked on the back side of the silicon substrate 100. The back passivation contact structure 500 includes a second silicon oxide layer 510 and a second doped layer 520 sequentially arranged in a direction from the silicon substrate 100 to away from the silicon substrate 100, and the back metal electrode 600 is connected to the second doped layer 520. Through the above arrangement, a front passivation contact structure 300 is prepared on the front side of the silicon substrate 100, and the front metal electrode 400 does not need to be in direct contact with the p+ layer 200, thereby reducing the front contact recombination and improving the battery conversion efficiency. At the same time, the front passivation contact structure 300 can be directly prepared on the p+ layer 200, and no mask is required on the front side. Moreover, the front passivation contact structure 300 and the back passivation contact structure 500, and at the same time, since the first doping layer 320 in the front passivation contact structure 300 and the second doping layer 520 in the back passivation contact structure 500 have the same doping polarity, they can be formed in one step, thereby simplifying the preparation process and improving the preparation efficiency.

[0097] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A TOPCon battery, characterized in that: It includes a silicon substrate, a P+ layer, at least one front passivation contact structure, a front metal electrode, at least one back passivation contact structure and a back metal electrode; The P+ layer is arranged on the front side of the silicon substrate; At least one layer of the front passivation contact structure is stacked on the P+ layer, and the front passivation contact structure includes a first silicon oxide layer and a first doping layer sequentially arranged in a direction away from the silicon substrate; The front metal electrode is connected to the first doping layer; At least one layer of the back passivation contact structure is stacked on the back side of the silicon substrate, and the back passivation contact structure includes a second silicon oxide layer and a second doped layer sequentially arranged in a direction away from the silicon substrate, and the back metal electrode is connected to the second doped layer.

2. The TOPCon battery according to claim 1, characterized in that The P+ layer is disposed in a local area of ​​the front surface.

3. The TOPCon battery according to claim 2, characterized in that The width of the P+ layer is 20 micrometers to 2000 micrometers.

4. The TOPCon battery according to claim 2 or 3, characterized in that: At least two P+ layers are disposed on the front side, and the distance between two adjacent P+ layers is 100 micrometers to 5000 micrometers.

5. The TOPCon battery according to claim 1 or 2, characterized in that: The edge of the front passivation contact structure is directly opposite to or staggered from the edge of the P+ layer.

6. The TOPCon battery according to claim 1, characterized in that The width of the P+ layer is smaller than the width of the front passivation contact structure.

7. The TOPCon battery according to claim 1, characterized in that The TOPCon cell further includes a front passivation film, which is disposed on a side of the first doping layer away from the first silicon oxide layer, and the front metal electrode passes through the front passivation film and is connected to the first doping layer.

8. The TOPCon battery according to claim 7, characterized in that The TOPCon cell further includes a back passivation film, which is disposed on a side of the second doped layer away from the second silicon oxide layer, and the back metal electrode passes through the back passivation film and is connected to the second doped layer.

9. The TOPCon battery according to claim 8, characterized in that The front passivation film and the back passivation film include at least one of silicon nitride, aluminum oxide, silicon oxynitride, and silicon oxide.

10. The TOPCon battery according to claim 1, characterized in that The front surface and / or the back surface is a polished surface or a velvet surface.

11. The TOPCon battery according to claim 1, characterized in that The first doped layer and the second doped layer are both N-type doped polysilicon layers.

12. A photovoltaic module, characterized in that: Comprising the TOPCon battery as claimed in any one of claims 1 to 11.

13. A laminated battery, characterized in that: The invention comprises a perovskite cell and a TOPCon cell as claimed in any one of claims 1 to 11.

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