A back contact cell, cell assembly and photovoltaic system

Abstract

This invention relates to the field of photovoltaic technology and provides a back-contact battery, battery module, and photovoltaic system. The back-contact battery includes: a silicon substrate, the back side of which includes a first region and a second region, and a trench disposed between the first and second regions; a first doped layer disposed in the first region; a second doped layer disposed in the second region, the doping type of the second doped layer being opposite to that of the first doped layer; and an insulating filler layer filling the trench, the insulating filler layer including a first passivation layer covering the surface of the trench and a polymer insulating layer covering the first passivation layer. The back-contact battery of this invention can improve the electrical isolation effect between the second doped layer and the first doped layer, and can alleviate stress concentration at the trench location, reducing the risk of microcracks or warping of the back-contact battery.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and in particular to a back-contact battery, battery module and photovoltaic system. Background Technology

[0002] A solar cell is a semiconductor device that converts solar energy into electrical energy. Under sunlight, a photocurrent is generated inside the solar cell, which outputs electrical energy through electrodes. In recent years, solar cell manufacturing technology has continuously improved, production costs have decreased, and conversion efficiency has increased. Solar cell power generation has become increasingly widespread and is an important energy source for electricity supply. In particular, because the grid lines of the back-contact cell are all located on the back side, the grid lines can avoid shading the front of the cell, which greatly improves the cell efficiency.

[0003] In related technologies, the back side of a back contact battery is usually provided with a first doped layer and a second doped layer with opposite doping types. In order to achieve isolation between the first doped layer and the second doped layer, it is usually necessary to open a trench in the silicon substrate at the position between the first doped layer and the second doped layer. However, if only trenches are used to achieve isolation between the first doped layer and the second doped layer, there is still a problem that the electrical isolation effect between the first doped layer and the second doped layer is not good. Summary of the Invention

[0004] This invention provides a back contact battery, which aims to solve the problem that the existing back contact batteries only use trenches to achieve isolation between the first doped layer and the second doped layer, resulting in poor electrical isolation between the first doped layer and the second doped layer.

[0005] This invention is implemented by providing a back contact battery, comprising: A silicon substrate, the back side of which includes a first region and a second region, and the back side of which includes a trench disposed between the first region and the second region; A first doped layer is disposed in the first region; A second doped layer is provided in the second region, wherein the doping type of the second doped layer is opposite to that of the first doped layer; and An insulating filler layer is filled in the trench, the insulating filler layer comprising a first passivation layer covering the surface of the trench and a polymer insulating layer covering the first passivation layer.

[0006] Preferably, the total thickness of the insulating filler layer is greater than or equal to the depth of the trench.

[0007] Preferably, the surface of the polymer insulating layer away from the silicon substrate is flush with the surface of the first doped layer away from the silicon substrate; and / or, the surface of the polymer insulating layer away from the silicon substrate is flush with the surface of the second doped layer away from the silicon substrate.

[0008] Preferably, the thickness of the polymer insulating layer is greater than the thickness of the first passivation layer.

[0009] Preferably, the first passivation layer is a stack of one or at least two of the following: silicon nitride layer, silicon oxide layer, silicon oxynitride layer, and aluminum oxide layer.

[0010] Preferably, the polymer insulating layer comprises one or a combination of at least two of parylene, fluorinated polymer, epoxy resin, acrylate, polyimide, and phenolic resin.

[0011] Preferably, the insulating filler layer further includes: A connecting layer is provided between the first passivation layer and the polymer insulating layer.

[0012] Preferably, the connecting layer comprises one or a combination of at least two of silane coupling agents, silicone resins, and tetraethyl orthosilicate.

[0013] Preferably, the width of the trench is 1~90μm and the depth of the trench is 1~5μm.

[0014] Preferred options also include: A first electrode, the first electrode being in contact with the first doped layer; and The second electrode is in contact with the second doped layer.

[0015] Preferred options also include: A second passivation layer is provided covering the first doped layer and the second doped layer. The first electrode passes through the second passivation layer and contacts the first doped layer, and the second electrode passes through the second passivation layer and contacts the second doped layer.

[0016] Preferably, the second passivation layer and the first passivation layer are formed separately, and the second passivation layer covers the insulating filler layer.

[0017] Preferably, the second passivation layer is made of the same material as the first passivation layer.

[0018] Preferably, the second passivation layer is integrally formed with the first passivation layer.

[0019] Preferred options also include: An insulating protective layer covers the second passivation layer and the polymer insulating layer. The first electrode passes through the insulating protective layer and the second passivation layer and is in contact with the first doped layer. The second electrode passes through the insulating protective layer and the second passivation layer and is in contact with the second doped layer.

[0020] Preferably, the insulating protective layer is made of the same material as the polymer insulating layer.

[0021] Preferably, the insulating protective layer is integrally formed with the polymer insulating layer.

[0022] Preferably, at least a portion of the polymer insulating layer is hollowed out to form a hollow structure.

[0023] The present invention also provides a battery assembly including the aforementioned back contact battery.

[0024] The present invention also provides a photovoltaic system including the above-described battery module.

[0025] This invention provides a back-contact battery by forming a trench between a first region and a second region on the back side of a silicon substrate. The trench isolates a second doped layer and a first doped layer, and an insulating filling layer is formed within the trench. The insulating filling layer includes a first passivation layer covering the trench surface and a polymer insulating layer covering the first passivation layer. The first passivation layer passesivates the trench surface, reducing surface recombination losses at the trench location. At the same time, the excellent insulating properties of the polymer insulating layer further enhance the isolation effect of the trench, achieving good electrical isolation between the second and first doped layers. Moreover, due to the excellent stress buffering properties of the polymer insulating layer, stress concentration at the trench location can be alleviated, thereby reducing the risk of microcracks or warping in the back-contact battery and improving the structural stability of the back-contact battery. Attached Figure Description

[0026] Figure 1 A cross-sectional schematic diagram of a back contact battery according to an embodiment of the present invention; Figure 2 A schematic diagram of a back contact battery without an insulating filling layer in a specific embodiment of the present invention. Figure 3 A schematic diagram of the trench of a back contact battery after an insulating filling layer has been provided in an embodiment of the present invention; Figure 4 for Figure 3 A magnified schematic diagram of part A in the middle; Figure 5 A cross-sectional schematic diagram of a back-contact battery according to another embodiment of the present invention; Figure 6 A schematic diagram of the trench of the back contact battery with an insulating filling layer provided in another embodiment of the present invention; Figure 7 This is a cross-sectional schematic diagram of a back contact battery according to another embodiment of the present invention.

[0027] Explanation of key symbols: The back contact cell 100, silicon substrate 1, first region 11, second region 12, trench 13, first doped layer 2, second doped layer 3, insulating filling layer 4, first passivation layer 41, polymer insulating layer 42, first tunneling layer 5, second tunneling layer 6, first electrode 7, second electrode 8, connecting layer 43, second passivation layer 15, and insulating protective layer 16. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Examples of embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the invention, and should not be construed as limiting the invention. Furthermore, it should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0029] In the description of this invention, it should be understood that the terms "upper", "lower", "backlight", "front", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0030] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0031] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0032] Please refer to Figures 1-3 This invention provides a back contact battery 100, comprising: The back side of the silicon substrate 1 includes a first region 11 and a second region 12, and the back side of the silicon substrate 1 includes a trench 13 disposed between the first region 11 and the second region 12. A first doped layer 2 is disposed in the first region 11; A second doped layer 3 is provided in the second region 12, and the doping type of the second doped layer 3 is opposite to that of the first doped layer 2; and An insulating filling layer 4 is filled in the trench 13. The insulating filling layer 4 includes a first passivation layer 41 covering the surface of the trench 13 and a polymer insulating layer 42 covering the first passivation layer 41.

[0033] An embodiment of the present invention provides a back contact battery 100 by forming a trench 13 between a first region 11 and a second region 12 on the back side of a silicon substrate 1. The trench 13 physically isolates the second doped layer 3 and the first doped layer 2, and fills the trench 13 with an insulating filling layer 4. The insulating filling layer 4 includes a first passivation layer 41 covering the surface of the trench 13 and a polymer insulating layer 42 covering the first passivation layer 41. The first passivation layer 41 passesivates the surface of the trench 13, reducing surface recombination loss at the trench 13 location. At the same time, the polymer insulating layer 42 is formed of a polymer insulating material. Utilizing the good insulating properties of the polymer insulating material, the polymer insulating layer 42 can further improve the insulation effect at the trench 13 location, achieving good electrical isolation between the second doped layer 3 and the first doped layer 2. Moreover, since the polymer insulating layer 42 has excellent stress buffering properties, it can alleviate stress concentration at the trench 13 location, reducing the risk of microcracks or warping in the back contact battery 100 and improving the structural stability of the back contact battery 100.

[0034] In this embodiment of the invention, the silicon substrate 1 includes a back side and a front side disposed opposite to each other. The back side of the silicon substrate 1 is the side of the silicon substrate 1 that is away from sunlight when the back contact battery 100 is working normally, and the front side of the silicon substrate 1 is the side of the silicon substrate 1 that faces sunlight when the back contact battery 100 is working normally.

[0035] In this embodiment of the invention, one of the first doped layer 2 and the second doped layer 3 is a P-type doped layer and the other is an N-type doped layer, and the specific doping types of the first doped layer 2 and the second doped layer 3 are not limited. Specifically, the first doped layer 2 can be a P-type doped layer and the second doped layer 3 can be an N-type doped layer; or the first doped layer 2 can be an N-type doped layer and the second doped layer 3 can be a P-type doped layer. The P-type doped layer is doped with a P-type dopant, and the N-type doped layer is doped with an N-type dopant. The P-type dopant is a dopant of a Group IIIA element in the periodic table, and the N-type dopant is a dopant of a Group VA element in the periodic table. For example, the P-type dopant can be a boron dopant, and the N-type dopant can be a phosphorus dopant.

[0036] There are multiple first doped layers 2 and second doped layers 3. The first doped layers 2 and second doped layers 3 are alternately spaced along the first direction X. The first doped layers 2 and second doped layers 3 are provided with trenches 13, and the trenches 13 are filled with insulating filler layers 4. In this way, the first doped layers 2 and second doped layers 3 are isolated from each other by the trenches 13 and the insulating filler layers 4 in the trenches 13, so as to achieve good electrical isolation between the second doped layer 3 and the first doped layer 2.

[0037] In one embodiment of the present invention, the first doped layer 2 and the second doped layer 3 may be at least one of a doped polycrystalline silicon layer, a doped amorphous silicon layer, a doped microcrystalline silicon layer, and a doped nanocrystalline silicon layer. Preferably, both the first doped layer 2 and the second doped layer 3 are doped polycrystalline silicon layers.

[0038] As one embodiment of the present invention, it also includes: The first tunneling layer 5 is disposed between the first doped layer 2 and the silicon substrate 1; The second tunneling layer 6 is disposed between the second doped layer 3 and the silicon substrate 1.

[0039] In this embodiment, the first tunneling layer 5 is disposed between the first doped layer 2 and the silicon substrate 1, and the second tunneling layer 6 is disposed between the second doped layer 3 and the silicon substrate 1. The first tunneling layer 5 and the second tunneling layer 6 passivate the surface of the silicon substrate 1 and allow carriers to pass through efficiently. The materials of the first tunneling layer 5 and the second tunneling layer 6 can be the same or different.

[0040] As an embodiment of the present invention, the first tunneling layer 5 and the second tunneling layer 6 are stacked layers of one or more of the following: silicon oxide layer, aluminum oxide layer, silicon nitride layer, and silicon oxynitride layer.

[0041] As one embodiment of the present invention, it also includes: The first electrode 7 is in contact with the first doped layer 2; and The second electrode 8 is in contact with the second doped layer 3.

[0042] In this embodiment, the first electrode 7 can be in direct or indirect contact with the first doped layer 2; similarly, the second electrode 8 can be in direct or indirect contact with the second doped layer 3. For example, when both the first doped layer 2 and the second doped layer 3 are polycrystalline silicon layers, the first electrode 7 is in direct contact with the first doped layer 2, and the second electrode 8 is in direct contact with the second doped layer 3; when both the first doped layer 2 and the second doped layer 3 are amorphous silicon layers, a conductive film is disposed between the first electrode 7 and the first doped layer 2, and the first electrode 7 and the first doped layer 2 are indirectly contacted through the conductive film; a conductive film is disposed between the second electrode 8 and the second doped layer 3, and the second electrode 8 and the second doped layer 3 are indirectly contacted through the conductive film.

[0043] Please refer to the reference. Figure 3 and Figure 4 As an embodiment of the present invention, the total thickness D of the insulating filler layer 4 is greater than or equal to the depth H of the trench 13.

[0044] In this embodiment, the total thickness D of the insulating filler layer 4 is the sum of the thicknesses of all the film layers of the insulating filler layer 4. When the insulating filler layer 4 includes a first passivation layer 41 and a polymer insulating layer 42, the total thickness D of the insulating filler layer 4 is the sum of the thickness D1 of the first passivation layer 41 and the thickness D2 of the polymer insulating layer 42.

[0045] In this embodiment, the total thickness D of the insulating filling layer 4 is controlled to be greater than or equal to the depth H of the trench 13, so that the insulating filling layer 4 can completely fill the trench 13, which can better achieve good electrical isolation between the insulating filling layer 4 and the first doped layer 2 and the second doped layer 3; moreover, it is beneficial for the polymer insulating layer 42 to better alleviate the stress concentration at the position of the trench 13, and further reduce the risk of microcracks or warping of the back contact battery 100.

[0046] As an embodiment of the present invention, the surface of the polymer insulating layer 42 away from the silicon substrate 1 is flush with the surface of the first doped layer 2 away from the silicon substrate 1; and / or, the surface of the polymer insulating layer 42 away from the silicon substrate 1 is flush with the surface of the second doped layer 3 away from the silicon substrate 1.

[0047] In this embodiment, the surface of the first doped layer 2 away from the silicon substrate 1 and the surface of the second doped layer 3 away from the silicon substrate 1 may or may not be flush. When the surface of the first doped layer 2 away from the silicon substrate 1 and the surface of the second doped layer 3 away from the silicon substrate 1 are flush, the surface of the polymer insulating layer 42 away from the silicon substrate 1 is flush with the surface of the first doped layer 2 away from the silicon substrate 1, and the surface of the polymer insulating layer 42 away from the silicon substrate 1 is also flush with the surface of the second doped layer 3 away from the silicon substrate 1. When the surface of the first doped layer 2 away from the silicon substrate 1 and the surface of the second doped layer 3 away from the silicon substrate 1 are not flush, the surface of the polymer insulating layer 42 away from the silicon substrate 1 is either flush with the surface of the first doped layer 2 away from the silicon substrate 1 or flush with the surface of the second doped layer 3 away from the silicon substrate 1. Making the surface of the polymer insulating layer 42 away from the silicon substrate 1 flush with the surface of at least one of the first doped layer 2 and the second doped layer 3 away from the silicon substrate 1 can further improve the isolation effect of the insulating filling layer 4 between the first doped layer 2 and the second doped layer 3.

[0048] As an embodiment of the present invention, the thickness D2 of the polymer insulating layer 42 is greater than the thickness D1 of the first passivation layer 41.

[0049] In this embodiment, the thickness D2 of the polymer insulating layer 42 is controlled to be greater than the thickness D1 of the first passivation layer 41, which is more conducive to improving the insulation performance of the polymer insulating layer 42, improving the insulation effect at the trench 13 position, further improving the electrical isolation effect between the second doped layer 3 and the first doped layer 2, and also helps to improve the stress concentration relief effect of the polymer insulating layer 42 at the trench 13 position, further reducing the risk of microcracks or warping in the back contact battery 100.

[0050] As an embodiment of the present invention, the ratio of the thickness D2 of the polymer insulating layer 42 to the thickness D1 of the first passivation layer 41 is 2 to 20.

[0051] In this embodiment, the ratio of the thickness D2 of the polymer insulating layer 42 to the thickness D1 of the first passivation layer 41 is controlled to be 2~20, which is beneficial to further improve the insulation performance of the polymer insulating layer 42, improve the insulation effect at the trench 13 position, further improve the electrical isolation effect between the second doped layer 3 and the first doped layer 2, and also helps to improve the stress concentration relief of the polymer insulating layer 42 at the trench 13 position, further reducing the risk of microcracks or warping of the back contact battery 100.

[0052] For example, the ratio of the thickness D2 of the polymer insulating layer 42 to the thickness D1 of the first passivation layer 41 can be any value among 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, and 20.

[0053] In a preferred embodiment of the present invention, the ratio of the thickness D2 of the polymer insulating layer 42 to the thickness D1 of the first passivation layer 41 is 2 to 10.

[0054] In this embodiment, the ratio of the thickness D2 of the polymer insulating layer 42 to the thickness D1 of the first passivation layer 41 is further controlled to be 2~20. Under the premise that the total thickness of the insulating filling layer 4 is constant, the thickness D2 of the polymer insulating layer 42 and the thickness D1 of the first passivation layer 41 can be better matched. This can ensure the insulation effect of the polymer insulating layer 42 and the stress concentration relief effect of the polymer insulating layer 42 on the trench 13, while ensuring the good passivation effect of the first passivation layer 41.

[0055] As an embodiment of the present invention, the first passivation layer 41 is a stack of one or more of the following: silicon nitride layer, silicon oxide layer, silicon oxynitride layer, and aluminum oxide layer.

[0056] In this embodiment, the first passivation layer 41 can be a single-layer structure or a structure with two or more layers. When the first passivation layer 41 is a single layer, it can be one of a silicon nitride layer, a silicon oxide layer, a silicon oxynitride layer, or an aluminum oxide layer. When the first passivation layer 41 is a structure with two or more layers, it can be a stacked structure of at least two of the following: a silicon nitride layer, a silicon oxide layer, a silicon oxynitride layer, or an aluminum oxide layer. Preferably, the first passivation layer 41 includes at least one silicon nitride layer, which can achieve a good passivation effect and ensure that the first passivation layer 41 has a good insulation effect.

[0057] As an embodiment of the present invention, the polymer insulating layer 42 includes one or a combination of at least two of parylene, fluorinated polymer, epoxy resin, acrylate, polyimide, and phenolic resin.

[0058] In this embodiment, the polymer insulating layer 42 can be one or a combination of at least two of parylene, fluorinated polymers, epoxy resins, acrylates, polyimides, and phenolic resins. Using these materials in the polymer insulating layer 42 ensures good insulation performance, which is beneficial for improving the insulation effect at the trench 13 location. It also ensures good stress relief at the trench 13 location, reducing the risk of microcracks or warping in the back contact battery 100. Of course, the specific material of the polymer insulating layer 42 is not limited to these; it can also be other polymer insulating materials.

[0059] In a preferred embodiment of the present invention, the polymer insulating layer 42 includes one or a combination of parylene and fluorinated polymers.

[0060] In this embodiment, since parylene and fluorinated polymers have better weather resistance, stronger insulation and better water vapor barrier properties than epoxy resin, acrylate, polyimide and phenolic resin, they can better ensure the good insulation performance of the polymer insulating layer 42 and achieve good isolation between the first doped layer 2 and the second doped layer 3.

[0061] Parylene can be one or more of Parylene C, Parylene N, or Parylene HT. Parylene C, with its extremely low permeability, high breakdown strength, and good uniformity, can effectively achieve isolation between the first doped layer 2 and the second doped layer 3, making it better suited for back-contact batteries. Parylene N, with its low dielectric constant, and Parylene HT, with its excellent high-temperature resistance (long-term temperature resistance up to 350℃), are suitable for back-contact batteries requiring high-temperature sintering processes (such as some TBC batteries).

[0062] As an embodiment of the present invention, the polymer insulating layer 42 includes parylene, which includes at least Parylene C, and the mass percentage of Parylene C is ≥50%, which can better achieve isolation between the first doped layer 2 and the second doped layer 3.

[0063] In one embodiment of the present invention, the polymer insulating layer 42 comprises parylene, and the volume resistivity of the polymer insulating layer 42 is 10¹⁰. 6 ~10¹ 7 The dielectric strength is 200~300kV / mm, the dielectric constant is 2.65~3.1, and the thickness uniformity of the polymer insulating layer 42 is controlled within ±5%, so that the polymer insulating layer 42 is free of pinhole defects, which can effectively avoid leakage between the first doped layer 2 and the second doped layer 3.

[0064] In another embodiment of the present invention, the polymer insulating layer 42 includes a fluorinated polymer, which is one or more of PVDF (polyvinylidene fluoride), ETFE (ethylene-tetrafluoroethylene copolymer), or PTFE (polytetrafluoroethylene).

[0065] Among them, PVDF (polyvinylidene fluoride) is more suitable for mass production of back contact batteries because it is solution-processable, has good toughness, strong adhesion, and low cost; while ETFE (ethylene-tetrafluoroethylene copolymer) has a low dielectric constant and extremely strong weather resistance, making it suitable for high-voltage BC batteries; PTFE (polytetrafluoroethylene) has the lowest dielectric constant, with a dielectric constant of 2.0~2.1, and its insulation performance is better than other fluorinated polymers, but it is difficult to process and has poor adhesion, so it needs to be modified by blending to improve its processability.

[0066] Specifically, when the polymer insulating layer 42 is made solely of PVDF (polyvinylidene fluoride), it is prepared into a solution using DMF (dimethylformamide), NMP (N-methylpyrrolidone), or DMSO (dimethyl sulfoxide) as solvents. After curing, the polymer insulating layer 42 is dense and non-porous, with a dielectric constant of 6-8 and a temperature resistance of ≤150℃, which can withstand the conventional metallization and sintering processes (≤200℃) of back contact batteries. When the polymer insulating layer 42 is made solely of ETFE (ethylene-tetrafluoroethylene copolymer), it is hot-melt extruded into a film and then hot-pressed. It has a dielectric constant of 2.6, a temperature resistance of ≤150℃, and good light transmittance, making it suitable for compatibility with transparent passivation layers. When the polymer insulating layer 42 is made solely of PTFE (polytetrafluoroethylene), it is sprayed with a nano-dispersion solution. High-temperature sintering, or, the polymer insulating layer 42 is a mixture of PTFE (polytetrafluoroethylene) and PVDF (polyvinylidene fluoride). PTFE (polytetrafluoroethylene) and PVDF (polyvinylidene fluoride) are blended and modified at a mass ratio of 1:2 to 1:5. After modification, the processability of PTFE (polytetrafluoroethylene) and its adhesion to silicon wafers and metal electrodes can be significantly improved. The dielectric constant can be controlled between 2.5 and 4.0, and the temperature resistance is ≤260℃. It can be adapted to high-temperature process back contact batteries. After the polymer insulating layer 42 is subjected to damp heat aging (temperature 85℃±2℃, relative humidity 85%±3%RH, duration 1000h), the insulation performance of the polymer insulating layer 42 decreases by ≤20%, ensuring the long-term reliability of the battery in complex outdoor environments.

[0067] As an embodiment of the present invention, the width W of the groove 13 is 1~90μm and the depth H of the groove 13 is 1~5μm.

[0068] In this embodiment, the width W of the trench 13 is the dimension of the trench 13 along the first direction X. The width W of the trench 13 is controlled to be 1~90μm and the depth H of the trench 13 is 1~5μm, which helps to ensure a good isolation effect of the trench 13 on the first doped layer 2 and the second doped layer 3, and facilitates the preparation of the insulating filling layer 4.

[0069] For example, the width W of the trench 13 may be 1 μm, 2 μm, 3 μm, 5 μm, 6 μm, 9 μm, 10 μm, 12 μm, 15 μm, 20 μm, 25 μm, 26 μm, 30 μm, 32 μm, 34 μm, 36 μm. , 38μm, 40μm, 45μm, 50μm, 51μm, 55μm, 58μm, 60μm, 65μm, 70μm, 73μm, 76μm, 80μm, 83μm, 85μm, 90μm.

[0070] For example, the depth H of the trench 13 can be any value among 1μm, 1.1μm, 1.3μm, 1.5μm, 1.8μm, 2μm, 2.1μm, 2.2μm, 2.4μm, 2.5μm, 2.6μm, 2.8μm, 3μm, 3.2μm, 3.5μm, 3.6μm, 3.8μm, 4μm, 4.1μm, 4.3μm, 4.5μm, 4.7μm, 4.8μm, and 5μm.

[0071] As one embodiment of the present invention, it also includes: A second passivation layer 15 is provided on the first doped layer 2 and the second doped layer 3. The first electrode 7 passes through the second passivation layer 15 and contacts the first doped layer 2, and the second electrode 8 passes through the second passivation layer 15 and contacts the second doped layer 3.

[0072] In this embodiment, the second passivation layer 15 can saturate the dangling bonds on the surfaces of the first doped layer 2 and the second doped layer 3, further reducing the interface state density and improving the passivation quality. Additionally, the second passivation layer 15 can serve as an anti-reflection film on the back side of the back contact battery, reducing the reflection of sunlight from the back side, increasing the utilization of sunlight on the back side of the silicon substrate 1, and improving the back side power generation efficiency.

[0073] As an embodiment of the present invention, the second passivation layer 15 is a stack of one or more of the following: silicon nitride layer, silicon oxide layer, silicon oxynitride layer, and aluminum oxide layer.

[0074] In this embodiment, the second passivation layer 15 can be a single-layer structure or a structure with two or more layers. When the second passivation layer 15 is a single layer, it can be one of a silicon nitride layer, a silicon oxide layer, a silicon oxynitride layer, or an aluminum oxide layer. When the second passivation layer 15 is a structure with two or more layers, it can be a stacked structure of at least two of the following: a silicon nitride layer, a silicon oxide layer, a silicon oxynitride layer, or an aluminum oxide layer. Preferably, the second passivation layer 15 includes at least one silicon nitride layer, which can achieve a good passivation effect, ensure good insulation, and guarantee good anti-reflection properties.

[0075] As an embodiment of the present invention, the second passivation layer 15 and the first passivation layer 41 are separately formed, and the second passivation layer 15 covers the insulating filler layer 4.

[0076] In this embodiment, the second passivation layer 15 is prepared separately from the first passivation layer 41. An insulating filling layer 4 and a polymer insulating layer 42 can be prepared first within the trench 13, followed by the preparation of the second passivation layer 15. This ensures that the second passivation layer 15 covers the insulating filling layer 4, and also covers the first doped layer 2 and the second doped layer 3. This allows for the use of different materials to prepare the second passivation layer 15 and the first passivation layer 41, facilitating differentiated designs between them. For example, the first passivation layer 41 can be made of an insulating material with better insulation properties than the second passivation layer 15 to increase the electrical isolation effect of the insulating filler layer 4; or, for example, the thickness difference between the second passivation layer 15 and the first passivation layer 41 can be controlled so that the thickness of the first passivation layer 41 is greater than the thickness of the second passivation layer 15, that is, the thickness of the first passivation layer 41 is increased to enhance the electrical isolation effect of the insulating filler layer 4; in addition, the second passivation layer 15 can be made of a film material with better passivation properties than the first passivation layer 41, which is beneficial to improving the passivation performance of the second passivation layer 15.

[0077] As an embodiment of the present invention, the second passivation layer 15 is made of the same material as the first passivation layer 41.

[0078] In this embodiment, the second passivation layer 15 is made of the same material as the first passivation layer 41, which facilitates the simultaneous fabrication of the second passivation layer 15 and the first passivation layer 41. For example, both the second passivation layer 15 and the first passivation layer 41 can be silicon nitride layers.

[0079] As an embodiment of the present invention, the second passivation layer 15 is integrally formed with the first passivation layer 41.

[0080] In this embodiment, the second passivation layer 15 and the first passivation layer 41 are integrally formed, that is, the second passivation layer 15 and the first passivation layer 41 are prepared simultaneously. Alternatively, the second passivation layer 15 and the first passivation layer 41 can be prepared in one step, and then the polymer insulating layer 42 can be prepared, which simplifies the process and reduces production costs.

[0081] Please refer to Figure 5 and Figure 6 As one embodiment of the present invention, it further includes: An insulating protective layer 16 covers a second passivation layer 15 and a polymer insulating layer 42. A first electrode 7 passes through the insulating protective layer 16 and the second passivation layer 15 and contacts the first doped layer 2. A second electrode 8 passes through the insulating protective layer 16 and the second passivation layer 15 and contacts the second doped layer 3.

[0082] In this embodiment, by providing an insulating protective layer 16 to cover the second passivation layer 15 and the polymer insulating layer 42, the insulating protective layer 16 can protect the second passivation layer 15 and the polymer insulating layer 42, preventing them from being scratched. This ensures the good passivation performance of the second passivation layer 15 and guarantees the good isolation effect of the polymer insulating layer 42. Moreover, due to the presence of the insulating protective layer 16, it can further provide good isolation for the first electrode 7 and the second electrode 8, reducing the risk of short circuit between the first electrode 7 and the second electrode 8.

[0083] As an embodiment of the present invention, the insulating protective layer 16 is made of the same material as the polymer insulating layer 42.

[0084] In this embodiment, the insulating protective layer 16 and the polymer insulating layer 42 are made of the same material, which facilitates the simultaneous preparation of the insulating protective layer 16 and the polymer insulating layer 42.

[0085] As an embodiment of the present invention, the insulating protective layer 16 and the polymer insulating layer 42 are integrally formed.

[0086] In this embodiment, the second passivation layer 15 and the first passivation layer 41 are prepared in one go, and the insulating protective layer 16 and the polymer insulating layer 42 are prepared in one go, which can simplify the production process and reduce production costs.

[0087] As an embodiment of the present invention, at least a portion of the polymer insulating layer 42 is hollowed out to form a hollow structure.

[0088] In this embodiment, at least a portion of the interior of the polymer insulating layer 42 is hollowed out to form a hollow structure. Specifically, the hollow structure can be pores distributed within the polymer insulating layer 42. Thus, by providing a hollow structure within the polymer insulating layer 42, the insulation performance of the polymer insulating layer 42 can be further enhanced, thereby further improving the isolation effect of the polymer insulating layer 42 on the first doped layer 2 and the second doped layer 3. In some embodiments, both the polymer insulating layer 42 and the first passivation layer 41 are provided with hollow structures, and the number of hollow structures per unit area of ​​the polymer insulating layer 42 is greater than the number of hollow structures per unit area of ​​the first passivation layer 41. This ensures both good insulation and stress buffering effects of the polymer insulating layer 42, and good passivation effects of the first passivation layer 41.

[0089] Please refer to Figure 7 As an embodiment of the present invention, the insulating filler layer 4 further includes: A connecting layer 43 is disposed between the first passivation layer 41 and the polymer insulating layer 42.

[0090] In this embodiment, the connecting layer 43 is used to connect the first passivation layer 41 and the polymer insulating layer 42, enhance the connection stability between the first passivation layer 41 and the polymer insulating layer 42, prevent the polymer insulating layer 42 from falling off, and prevent the polymer insulating layer 42 from cracking, thereby enhancing the structural stability of the insulating filler layer 4.

[0091] As an embodiment of the present invention, the connecting layer 43 includes one or a combination of at least two of silane coupling agents, organosilicon resins, and tetraethyl orthosilicate.

[0092] In this embodiment, the connecting layer 43 includes one or a combination of silane coupling agent, organosilicon resin, and tetraethyl orthosilicate. The connecting layer 43 is provided with the above materials and acts as an interfacial molecular bridge between the first passivation layer 41 and the polymer insulating layer 42, thereby significantly improving adhesion, water resistance and insulation stability. In addition, it can better prevent the polymer insulating layer 42 from falling off and prevent the polymer insulating layer 42 from cracking, thereby enhancing the structural stability of the insulating filler layer 4.

[0093] This invention also provides a battery assembly, which includes the back contact battery 100 described in the above embodiments. It should be noted that this battery assembly has the same or similar beneficial effects as the back contact battery 100, and the related aspects between the two can be referred to each other; to avoid repetition, they will not be repeated here.

[0094] In this embodiment, multiple back-contact batteries 100 in the battery assembly are connected in series by solder strips to form a battery string, thereby achieving series current collection and output.

[0095] It is understood that in such embodiments, the battery assembly may further include a metal frame, a backsheet, photovoltaic glass, and an encapsulating film. The encapsulating film may be filled between the front and back surfaces of the back contact battery 100, the photovoltaic glass, adjacent battery cells, etc. As a filler, it may be a transparent colloid with good light transmittance and aging resistance. For example, the encapsulating film may be an EVA film or a POE film, and the specific choice can be made according to the actual situation, without limitation.

[0096] Photovoltaic glass can be applied to the encapsulating film on the front side of the back contact cell 100. The photovoltaic glass can be ultra-clear glass, which has high light transmittance, high transparency, and superior physical, mechanical, and optical properties. For example, ultra-clear glass can achieve a light transmittance of over 92%. It can protect the back contact cell 100 while minimizing impact on its efficiency. Simultaneously, the encapsulating film bonds the photovoltaic glass and the back contact cell 100 together, providing sealing, insulation, and waterproofing / moisture protection for the back contact cell 100.

[0097] The backsheet can be attached to the adhesive film on the back side of the back contact cell 100. The backsheet provides protection and support for the back contact cell 100, and offers reliable insulation, water resistance, and aging resistance. Multiple options are available for the backsheet, typically tempered glass, acrylic glass, or aluminum alloy TPT composite adhesive film, etc., and the specific choice is determined based on the specific circumstances and is not limited here. The backsheet, back contact cell 100, adhesive film, and photovoltaic glass can be mounted on a metal frame. The metal frame serves as the main external support structure for the entire battery module, providing stable support and installation. For example, the battery module can be installed at the desired location using the metal frame.

[0098] This invention also provides a photovoltaic system, which includes the battery module described in the above embodiments. It should be noted that this photovoltaic system has the same or similar beneficial effects as the back-contact battery 100 described above, and the related aspects between the two can be referred to each other; to avoid repetition, they will not be repeated here.

[0099] In this embodiment, the photovoltaic system can be applied in photovoltaic power plants, such as ground-mounted power plants, rooftop power plants, and floating power plants. It can also be applied to equipment or devices that utilize solar energy to generate electricity, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it is understood that the application scenarios of the photovoltaic system are not limited to these; that is, the photovoltaic system can be applied in all fields that require solar energy to generate electricity. Taking a photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a combiner box, and an inverter. The photovoltaic array may be an array combination of multiple battery modules; for example, multiple battery modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the combiner box, which can collect the current generated by the photovoltaic array. The collected current flows through the inverter and is converted into AC power required by the mains power grid before being connected to the mains power grid to achieve solar power supply.

[0100] In the description of this specification, references to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0101] The above are merely 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 within the protection scope of the present invention.

Claims

1. A back-contact battery, characterized in that, include: A silicon substrate, the back side of which includes a first region and a second region, and the back side of which includes a trench disposed between the first region and the second region; A first doped layer is disposed in the first region; A second doped layer is provided in the second region, wherein the doping type of the second doped layer is opposite to that of the first doped layer; and An insulating filling layer is disposed in the trench, the insulating filling layer comprising a first passivation layer covering the surface of the trench and a polymer insulating layer covering the first passivation layer.

2. The back contact battery according to claim 1, characterized in that, The total thickness of the insulating filler layer is greater than or equal to the depth of the trench.

3. The back contact battery according to claim 1, characterized in that, The surface of the polymer insulating layer away from the silicon substrate is flush with the surface of the first doped layer away from the silicon substrate; and / or, the surface of the polymer insulating layer away from the silicon substrate is flush with the surface of the second doped layer away from the silicon substrate.

4. The back contact battery according to claim 1, characterized in that, The thickness of the polymer insulating layer is greater than the thickness of the first passivation layer.

5. The back contact battery according to claim 1, characterized in that, The first passivation layer is a stack of one or more of the following: silicon nitride layer, silicon oxide layer, silicon oxynitride layer, and aluminum oxide layer.

6. The back contact battery according to claim 1, characterized in that, The polymer insulating layer comprises one or a combination of at least two of the following: parylene, fluorinated polymer, epoxy resin, acrylate, polyimide, and phenolic resin.

7. The back contact battery according to claim 1, characterized in that, The insulating filler layer further includes: A connecting layer is provided between the first passivation layer and the polymer insulating layer.

8. The back contact battery according to claim 7, characterized in that, The connecting layer comprises one or a combination of at least two of the following: silane coupling agent, organosilicon resin, and tetraethyl orthosilicate.

9. The back contact battery according to claim 1, characterized in that, The width of the trench is 1~90μm and the depth of the trench is 1~5μm.

10. The back contact battery according to claim 1, characterized in that, Also includes: The first electrode is in contact with the first doped layer; and The second electrode is in contact with the second doped layer.

11. The back contact battery according to claim 10, characterized in that, Also includes: A second passivation layer is provided covering the first doped layer and the second doped layer. The first electrode passes through the second passivation layer and contacts the first doped layer, and the second electrode passes through the second passivation layer and contacts the second doped layer.

12. The back contact battery according to claim 11, characterized in that, The second passivation layer is formed separately from the first passivation layer, and the second passivation layer covers the insulating filler layer.

13. The back contact battery according to claim 11, characterized in that, The second passivation layer is made of the same material as the first passivation layer.

14. The back contact battery according to claim 13, characterized in that, The second passivation layer is integrally formed with the first passivation layer.

15. The back contact battery according to claim 11, characterized in that, Also includes: An insulating protective layer covers the second passivation layer and the polymer insulating layer. The first electrode passes through the insulating protective layer and the second passivation layer and is in contact with the first doped layer. The second electrode passes through the insulating protective layer and the second passivation layer and is in contact with the second doped layer.

16. The back contact battery according to claim 15, characterized in that, The insulating protective layer is made of the same material as the polymer insulating layer.

17. The back contact battery according to claim 16, characterized in that, The insulating protective layer is integrally formed with the polymer insulating layer.

18. The back contact battery according to claim 1, characterized in that, At least a portion of the polymer insulating layer is hollowed out to form a hollow structure.

19. A battery assembly, characterized in that, Includes the back contact battery as described in any one of claims 1 to 18.

20. A photovoltaic system, characterized in that, Includes the battery assembly as described in claim 19.

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