A back contact cell, cell assembly and photovoltaic system

Abstract

The application belongs to the technical field of photovoltaics, and provides a back contact cell, a cell module and a photovoltaic system. The back contact cell comprises a silicon substrate, a first doped layer and a second doped layer arranged on the back surface of the silicon substrate, and the doping type of the second doped layer is opposite to that of the first doped layer. The first doped layer comprises a first lightly doped part, and the second doped layer comprises a second lightly doped part. The first lightly doped part is arranged adjacent to the second lightly doped part, and the doping concentration of the first lightly doped part and the second lightly doped part is less than or equal to 1E19 / cm 3 3. A first tunneling layer arranged between the silicon substrate and the first doped layer, and a second tunneling layer arranged between the silicon substrate and the second doped layer. An isolation layer is arranged between the first lightly doped part and the second lightly doped part. The back contact cell of the application does not need to arrange a groove on the silicon substrate to isolate the first doped layer and the second doped layer, thereby avoiding the serious recombination loss caused by the groove, and being beneficial to improving the cell conversion efficiency.

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 solar cell generates a photocurrent, which is then output as 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 side of the cell. Compared to bifacial cells with grid lines on both the front and back sides, this improves cell efficiency.

[0003] In related technologies, the back side of a back-contact battery typically features a first doped layer and a second doped layer with opposite doping types. To achieve isolation between the first and second doped layers, trenches are usually formed in the silicon substrate between them. However, forming trenches in the silicon substrate can cause damage to the crystal structure due to the high-temperature thermal stress generated on the silicon substrate surface by laser etching. The trenches can become carrier recombination centers, resulting in significant recombination losses in the silicon substrate and thus affecting the battery conversion efficiency. Summary of the Invention

[0004] This invention provides a back-contact battery, which aims to solve the problem that existing back-contact batteries require trenches to be opened on the silicon substrate, resulting in large recombination losses on the silicon substrate and thus affecting the battery conversion efficiency.

[0005] This invention is implemented by providing a back contact battery, comprising: Silicon substrate, the silicon substrate including a back side; A first doped layer and a second doped layer are disposed on the back side, the second doped layer and the first doped layer having opposite doping types, and the second doped layer and the first doped layer are alternately disposed along a first direction; the first doped layer includes a first lightly doped portion, the second doped layer includes a second lightly doped portion, the first lightly doped portion and the second lightly doped portion are disposed adjacent to each other, and the doping concentration of both the first lightly doped portion and the second lightly doped portion is less than or equal to 1E19 / cm³. 3 ; A first tunneling layer is disposed between the silicon substrate and the first doped layer; A second tunneling layer is disposed between the silicon substrate and the second doped layer; and An isolation layer is disposed between the first lightly doped portion and the second lightly doped portion.

[0006] Preferably, the doping concentration of the first lightly doped portion and the second lightly doped portion is 1E14 / cm². 3 ~1E19 / cm 3 .

[0007] Preferred options also include: A first electrode is disposed on the first doped layer, the first doped layer including a first heavily doped portion connected to the first lightly doped portion, the first electrode being in contact with the first heavily doped portion, and the doping concentration of the first heavily doped portion being greater than 1E19 / cm. 3 .

[0008] Preferably, the doping concentration of the first heavily doped portion is greater than 1E20 / cm². 3 .

[0009] Preferably, the dimension of the first heavily doped portion along the first direction is greater than the dimension of the first electrode along the first direction.

[0010] Preferably, the ratio of the doping concentration of the first lightly doped portion to the doping concentration of the second lightly doped portion is 1 to 100; or, the ratio of the doping concentration of the second lightly doped portion to the doping concentration of the first lightly doped portion is 1 to 100.

[0011] Preferred options also include: The second electrode is in contact with the second doped layer, the second doped layer including a second heavily doped portion connected to the second lightly doped portion, the second electrode being in contact with the second heavily doped portion, and the doping concentration of the second heavily doped portion being greater than 1E19 / cm². 3 .

[0012] Preferably, the first doped layer is an N-type doped layer, and the second doped layer is a P-type doped layer; the doping concentration of the second heavily doped portion is greater than 5E19 / cm³. 3 .

[0013] Preferably, the ratio of the length of the first lightly doped portion along the first direction to the length of the first heavily doped portion along the first direction is 0.006 to 15.

[0014] Preferably, the ratio of the length of the second lightly doped portion along the first direction to the length of the second heavily doped portion along the first direction is 0.006 to 15.

[0015] Preferably, the first doped layer includes a first boundary portion located between the first lightly doped portion and the first heavily doped portion, and along the first direction, the doping concentration of the first boundary portion near the first heavily doped portion is greater than the doping concentration of the first boundary portion near the first lightly doped portion.

[0016] Preferably, the second doped layer includes a second boundary portion located between the second lightly doped portion and the second heavily doped portion, and along the first direction, the doping concentration of the second boundary portion near the end of the second heavily doped portion is greater than the doping concentration of the second boundary portion near the end of the second lightly doped portion.

[0017] Preferably, the length of the first boundary portion along the first direction is 0.1 to 5 micrometers.

[0018] Preferably, the length of the second boundary portion along the first direction is 0.1 to 5 micrometers.

[0019] Preferably, both the first lightly doped portion and the first heavily doped portion are provided with pores, and the number of pores per unit area of ​​the first lightly doped portion is less than the number of pores per unit area of ​​the first heavily doped portion.

[0020] Preferably, both the first lightly doped portion and the first heavily doped portion are provided with holes, and the average maximum radial dimension of the holes in the first lightly doped portion is smaller than the average maximum radial dimension of the first heavily doped portion.

[0021] Preferably, both the second lightly doped portion and the second heavily doped portion are provided with pores, and the number of pores per unit area of ​​the second lightly doped portion is less than the number of pores per unit area of ​​the second heavily doped portion.

[0022] Preferably, both the second lightly doped portion and the second heavily doped portion are provided with pores, and the average maximum radial dimension of the pores in the second lightly doped portion is smaller than the average maximum radial dimension of the second heavily doped portion.

[0023] Preferably, the dimension of the second heavily doped portion along the first direction is greater than the dimension of the second electrode along the first direction.

[0024] Preferably, the first lightly doped portion includes a first portion connected to the first heavily doped portion, the isolation layer includes a first isolation portion connected to the first tunneling layer, the first isolation portion is bent away from the back side relative to the first tunneling layer, and the first isolation portion is located between the first portion and the second lightly doped portion.

[0025] Preferably, the first lightly doped portion includes a second portion connected to the first portion and bent away from the back side relative to the first portion, and the first isolation portion is also located between the second portion and the second lightly doped portion.

[0026] Preferably, the first lightly doped portion further includes a third portion connected to the second portion, the third portion being bent relative to the second portion, the third portion extending along the first direction toward the second doped layer, and the orthogonal projection of the third portion on the back side at least covering the first isolation portion.

[0027] Preferably, the isolation layer includes a second isolation portion connected to the first isolation portion, the second isolation portion being located between the third portion and the second lightly doped portion.

[0028] Preferably, the thickness of the second isolation portion along the thickness direction of the silicon substrate is greater than the thickness of the first isolation portion along the first direction.

[0029] Preferably, the first isolation section and the first tunneling layer are an integral structure.

[0030] Preferably, the first isolation portion is a stack of one or at least two of the following: a silicon oxide layer, an aluminum oxide layer, a silicon nitride layer, and a silicon oxynitride layer.

[0031] Preferably, the second isolation portion is a stack of one or at least two of the following: silicon oxide layer, aluminum oxide layer, silicon oxynitride layer, silicon nitride layer, borosilicate glass, and phosphosilicate glass.

[0032] Preferably, the refractive index of the second isolation portion is greater than that of the first isolation portion.

[0033] Preferably, the thickness of the second insulating portion is 5 to 100 nanometers.

[0034] Preferably, the thickness of the first insulating portion is 1 to 20 nanometers.

[0035] Preferably, the ratio of the thickness of the first isolation portion to the thickness of the first tunneling layer is 1 to 10.

[0036] Preferably, the ratio of the thickness of the first isolation portion to the thickness of the first tunneling layer is 1.1 to 5.

[0037] Preferred options also include: A barrier layer is disposed in at least a portion of the region between the first isolation portion and the second doped layer.

[0038] Preferably, the barrier layer is one or a combination of at least two of borosilicate glass, phosphosilicate glass, silicon oxide, silicon nitride, and silicon oxynitride.

[0039] Preferably, the surface of the second isolation portion facing away from the silicon substrate is provided with a textured structure.

[0040] Preferably, the first tunneling layer and the second tunneling layer are one or more of the following: silicon oxide layer, aluminum oxide layer, silicon nitride layer, and silicon oxynitride layer.

[0041] Preferably, the first doped layer and the second doped layer are one or a combination of at least two of the following: a doped polycrystalline silicon layer, a doped microcrystalline silicon layer, or a doped nanocrystalline silicon layer.

[0042] Preferred options also include: A passivation layer covers the first doped layer and the second doped layer. The first electrode passes through the passivation layer and contacts the first heavily doped portion, and the second electrode passes through the passivation layer and contacts the second heavily doped portion.

[0043] The present invention also provides a battery assembly including the aforementioned back contact battery.

[0044] The present invention also provides a photovoltaic system including the above-described battery module.

[0045] The present invention provides a back contact battery in which a first doped layer is configured to include a first lightly doped portion, and a second doped layer is configured to include a second lightly doped portion. The first lightly doped portion of the first doped layer and the second lightly doped portion of the second doped layer are disposed adjacent to each other, and the doping concentration of both the first lightly doped portion and the second lightly doped portion is controlled to be less than or equal to 1E19 / cm³. 3 This design results in weaker current transport capabilities between the first and second lightly doped portions, preventing conduction between the second and first doped layers and achieving electrical isolation between them. Simultaneously, an isolation layer is placed between the first and second lightly doped portions to physically separate them, further enhancing the electrical isolation effect. Thus, by setting low-doping concentrations for the first and second lightly doped portions, combined with the isolation layer, good electrical isolation between the second and first doped layers can be achieved. This eliminates the need to create trenches in the silicon substrate to isolate the first and second doped layers, avoiding severe recombination losses caused by trenches in the silicon substrate, thereby improving battery conversion efficiency.

[0046] Furthermore, the isolation layer can prevent doped atoms in the second doped layer and the first doped layer from diffusing into each other, preventing doped atoms in the second doped layer from diffusing into the first doped layer, and at the same time preventing doped atoms in the first doped layer from diffusing into the second doped layer. This avoids doped atoms in the second doped layer and the first doped layer from simultaneously expanding into the first tunneling layer and the second tunneling layer, preventing the first tunneling layer and the second tunneling layer from having too many porous structures, thereby ensuring a good passivation effect of the first tunneling layer and the second tunneling layer, which is conducive to further improving battery efficiency. Attached Figure Description

[0047] Figure 1 A cross-sectional schematic diagram of a back contact battery according to an embodiment of the present invention; Figure 2 for Figure 1 Enlarged schematic diagram of part A in the middle; Figure 3 A cross-sectional schematic diagram of a back-contact battery according to another embodiment of the present invention; Figure 4 This is a cross-sectional schematic diagram of a back contact battery according to another embodiment of the present invention.

[0048] Explanation of key symbols: The back contact cell 100, silicon substrate 1, back side 101, front side 102, first doped layer 2, second doped layer 3, first direction X, first tunneling layer 4, second tunneling layer 5, isolation layer 6, first lightly doped portion 21, first heavily doped portion 22, second lightly doped portion 31, second heavily doped portion 32, first electrode 7, second electrode 8, first boundary portion 23, second boundary portion 33, first part 211, second part 212, third part 213, first isolation portion 61, second isolation portion 62, barrier layer 12, textured structure 621. Detailed Implementation

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] An embodiment of the present invention provides a back contact battery in which a first doped layer is configured to include a first lightly doped portion, and a second doped layer is configured to include a second lightly doped portion, wherein the doping concentration of both the first lightly doped portion and the second lightly doped portion is controlled to be less than or equal to 1E19 / cm³. 3 Meanwhile, an isolation layer is set between the first lightly doped part and the second lightly doped part. By setting the first lightly doped part and the second lightly doped part with low doping concentration, and with the setting of the isolation layer, good electrical isolation between the second doped layer and the first doped layer can be achieved. There is no need to open trenches on the silicon substrate to isolate the first doped layer and the second doped layer, which avoids serious recombination loss caused by opening trenches on the silicon substrate, thereby helping to improve the cell conversion efficiency.

[0054] Please refer to Figure 1 and Figure 2 This invention provides a back contact battery 100, comprising: Silicon substrate 1, silicon substrate 1 includes a back surface 101; A first doped layer 2 and a second doped layer 3 are disposed on the back side 101. The doping types of the second doped layer 3 and the first doped layer 2 are opposite, and the second doped layer 3 and the first doped layer 2 are alternately disposed along the first direction X. The first doped layer 2 includes a first lightly doped portion 21, and the second doped layer 3 includes a second lightly doped portion 31. The first lightly doped portion 21 and the second lightly doped portion 31 are disposed adjacent to each other, and the doping concentration of both the first lightly doped portion 21 and the second lightly doped portion 31 is less than or equal to 1E19 / cm³. 3 ; The first tunneling layer 4 is disposed between the silicon substrate 1 and the first doped layer 2; The second tunneling layer 5 is disposed between the silicon substrate 1 and the second doped layer 3; and An isolation layer 6 is disposed between the second doped layer 3 and the first doped layer 2.

[0055] An embodiment of the present invention provides a back contact battery 100 by configuring a first doped layer 2 including a first lightly doped portion 21 and a second doped layer 3 including a second lightly doped portion 31. The first lightly doped portion 21 of the first doped layer 2 and the second lightly doped portion 31 of the second doped layer 3 are disposed adjacent to each other, and the doping concentration of both the first lightly doped portion 21 and the second lightly doped portion 31 is controlled to be less than or equal to 1E19 / cm. 3 This design results in weaker current transmission capabilities between the first lightly doped portion 21 and the second lightly doped portion 31, preventing conduction between the second doped layer 3 and the first doped layer 2 and achieving electrical isolation between them. Simultaneously, an isolation layer 6 is provided between the first lightly doped portion 21 and the second lightly doped portion 31, physically isolating them and further enhancing the electrical isolation effect. Thus, by setting low-doping concentration first lightly doped portions 21 and 31, combined with the isolation layer 6, good electrical isolation between the second doped layer 3 and the first doped layer 2 can be achieved. Therefore, it is unnecessary to create trenches on the silicon substrate 1 to isolate the first doped layer 2 and the second doped layer 3, avoiding severe recombination losses caused by trenches on the silicon substrate 1, thereby improving battery conversion efficiency.

[0056] In addition, the isolation layer 6 can block the doped atoms of the second doped layer 3 and the first doped layer 2 from diffusing into each other, preventing the doped atoms in the second doped layer 3 from diffusing into the first doped layer 2, and at the same time preventing the doped atoms in the first doped layer 2 from diffusing into the second doped layer 3. This avoids the doped atoms of the second doped layer 3 and the first doped layer 2 from simultaneously expanding into the first tunneling layer 4 and the second tunneling layer 5, and prevents the first tunneling layer 4 and the second tunneling layer 5 from being attacked by the doped atoms of the second doped layer 3 and the first doped layer 2 at the same time, thus preventing excessive pore structures. This ensures a good passivation effect of the first tunneling layer 4 and the second tunneling layer 5, which is more conducive to further improving battery efficiency.

[0057] In this embodiment of the invention, the silicon substrate 1 can specifically be an N-type silicon wafer. The silicon substrate 1 includes a back side 101 and a front side 102 disposed opposite to each other. The back side 101 of the silicon substrate 1 is the side of the silicon substrate 1 that faces away from sunlight when the back contact battery 100 is working normally, and the front side 102 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.

[0058] 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.

[0059] 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. An isolation layer 6 is provided between the first doped layers 2 and the second doped layers 3. The first lightly doped portion 21 of the first doped layer 2 and the second lightly doped portion 31 of the second doped layer 3 are arranged adjacent to each other, and the first lightly doped portion 21 of the first doped layer 2 and the second lightly doped portion 31 of the second doped layer 3 are isolated by the isolation layer 6 to achieve good electrical isolation between the second doped layer 3 and the first doped layer 2.

[0060] In this embodiment of the invention, the doping concentration of both the first lightly doped portion 21 and the second lightly doped portion 31 is less than or equal to 1E19 / cm³. 3 This can be understood as the concentration of active impurity atoms per unit volume of both the first lightly doped portion 21 and the second lightly doped portion 31 being less than or equal to 1E19 / cm³. 3 For example, if the doped atoms in the first doped layer 2 are phosphorus atoms and the doped atoms in the second doped layer 3 are boron atoms, then the concentration of activated phosphorus atoms in the first lightly doped portion 21 is less than or equal to 1E19 / cm³. 3 The concentration of activated boron atoms in the second lightly doped portion 31 is less than or equal to 1E19 / cm³. 3 Conversely, if the doped atoms in the first doped layer 2 are boron atoms and the doped atoms in the second doped layer 3 are phosphorus atoms, then the concentration of activated boron atoms in the first lightly doped portion 21 is less than or equal to 1E19 / cm³. 3 The concentration of activated phosphorus atoms in the second lightly doped portion 31 is less than or equal to 1E19 / cm³. 3 .

[0061] In this embodiment of the invention, the doping concentration of the first lightly doped portion 21 and the second lightly doped portion 31 can be less than or equal to 1E19 / cm². 3 The doping concentrations of the first lightly doped portion 21 and the second lightly doped portion 31 can be the same or different, depending on the value in the formula. For example, the doping concentrations of the first lightly doped portion 21 and the second lightly doped portion 31 can be 0 / cm³. 3 1E3 / cm 3 1E4 / cm 3 1E5 / cm 3 1E6 / cm 3 1E8 / cm 3 1E9 / cm 3 1E10 / cm 3 1E11 / cm 3 1E12 / cm 3 1E13 / cm 3 1E14 / cm 3 1E15 / cm 3 1E16 / cm 3 1E17 / cm 3 2E17 / cm 3 3E18 / cm 3 4E18 / cm 3 5E18 / cm 3 6E18 / cm 3 7E18 / cm 3 8E18 / cm 3 1E19 / cm 3 Any value in the range.

[0062] In one embodiment of the present invention, the doping concentration of the first lightly doped portion 21 and the second lightly doped portion 31 is 1E14 / cm². 3 ~1E19 / cm 3 .

[0063] In this embodiment, the doping concentration of the first lightly doped portion 21 and the second lightly doped portion 31 is controlled to be 1E14 / cm. 3 ~1E19 / cm 3 This can make the current transmission capability of the first lightly doped part 21 and the second lightly doped part 31 weaker, which can better prevent the second doped layer 3 from conducting with the first doped layer 2 and achieve electrical isolation between the second doped layer 3 and the first doped layer 2. At the same time, it can ensure the good passivation effect of the first lightly doped part 21 and the second lightly doped part 31.

[0064] As an embodiment of the present invention, the ratio of the doping concentration of the first lightly doped portion 21 to the doping concentration of the second lightly doped portion 31 is 1 to 100; or, the ratio of the doping concentration of the second lightly doped portion 31 to the doping concentration of the first lightly doped portion 21 is 1 to 100.

[0065] In this embodiment, the ratio of the doping concentration of the first lightly doped portion 21 to the doping concentration of the second lightly doped portion 31 is 1 to 100, that is, the doping concentration of the first lightly doped portion 21 is 1 to 100 times the doping concentration of the second lightly doped portion 31; or, the ratio of the doping concentration of the second lightly doped portion 31 to the doping concentration of the first lightly doped portion 21 is 1 to 100, that is, the doping concentration of the second lightly doped portion 31 is 1 to 100 times the doping concentration of the first lightly doped portion 21. Setting this ratio between the doping concentration of the first lightly doped portion 21 and the doping concentration of the second lightly doped portion 31 is beneficial to the drift and diffusion of electrons and holes, so that when the battery cell is shaded, it is beneficial to form a leakage current channel between the first lightly doped portion 21 and the second lightly doped portion 31 through the isolation layer 6, which can reduce the risk of hot spots and improve the safety and reliable power generation of the battery.

[0066] When the ratio of the doping concentration of the first lightly doped portion 21 to the doping concentration of the second lightly doped portion 31 is 1 to 100, the ratio can be any value among 1, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, and 100. Similarly, when the ratio of the doping concentration of the second lightly doped portion 31 to the doping concentration of the first lightly doped portion 21 is 1 to 100, the ratio can be any value among 1, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, and 100.

[0067] As an embodiment of the present invention, the ratio of the doping concentration of the first lightly doped portion 21 to the doping concentration of the second lightly doped portion 31 is 1 to 10; or, the ratio of the doping concentration of the second lightly doped portion 31 to the doping concentration of the first lightly doped portion 21 is 1 to 10.

[0068] When the ratio of the doping concentration of the first lightly doped portion 21 to the doping concentration of the second lightly doped portion 31 is 1 to 10, the ratio can be any value among 1, 2, 3, 5, 6, 7, 8, 9, and 10. Similarly, when the ratio of the doping concentration of the second lightly doped portion 31 to the doping concentration of the first lightly doped portion 21 is 1 to 10, the ratio can be any value among 1, 2, 3, 5, 6, 7, 8, 9, and 10.

[0069] As an embodiment of the present invention, the first doped layer 2 and the second doped layer 3 are one or a combination of at least two of the following: a doped polycrystalline silicon layer, a doped microcrystalline silicon layer, or a doped nanocrystalline silicon layer.

[0070] The materials of the first doped layer 2 and the second doped layer 3 can be the same or different. The first doped layer 2 and the second doped layer 3 can both be doped polycrystalline silicon layers, doped microcrystalline silicon layers, or doped nanocrystalline silicon layers; of course, the first doped layer 2 and the second doped layer 3 can also be a stacked structure of at least two of the following: doped polycrystalline silicon layers, doped microcrystalline silicon layers, or doped nanocrystalline silicon layers. Preferably, both the first doped layer 2 and the second doped layer 3 are doped polycrystalline silicon layers.

[0071] In one embodiment of the present invention, the first tunneling layer 4 and the second tunneling layer 5 are one or more stacks of silicon oxide, aluminum oxide, silicon nitride, and silicon oxynitride. The first tunneling layer 4 and the second tunneling layer 5 passivate the surface of the silicon substrate 1 and allow carriers to pass through efficiently. The materials of the first tunneling layer 4 and the second tunneling layer 5 can be the same or different.

[0072] As one embodiment of the present invention, it also includes: A first electrode 7 is disposed on a first doped layer 2. The first doped layer 2 includes a first heavily doped portion 22 connected to a first lightly doped portion 21. The first electrode 7 is in contact with the first heavily doped portion 22. The doping concentration of the first heavily doped portion 22 is greater than 1E19 / cm³. 3 .

[0073] In this embodiment, a first heavily doped portion 22 is provided at the position of the first electrode 7 in the first doped layer 2, and the doping concentration of the first heavily doped portion 22 is controlled to be greater than 1E19 / cm. 3 Within this concentration range, the first doped layer 22 can ensure a low contact resistance between the first doped layer 22 and the first electrode 7, achieving good ohmic contact between the first doped layer 2 and the first electrode 7, reducing battery electrical losses, and thus further improving battery conversion efficiency.

[0074] As an embodiment of the present invention, the doping concentration of the first heavily doped portion 22 is greater than 1E20 / cm. 3 .

[0075] In this embodiment, the doping concentration of the first heavily doped portion 22 is controlled to be greater than 1E20 / cm. 3 Increasing the doping concentration of the first doped portion 22 further reduces the contact resistance between the first doped portion 22 and the first electrode 7, further reducing battery electrical losses and thus further improving battery conversion efficiency.

[0076] As an embodiment of the present invention, the dimension L2 of the first heavily doped portion 22 along the first direction X is greater than the dimension L7 of the first electrode 7 along the first direction X.

[0077] In this embodiment, the dimension L2 of the first heavily doped portion 22 along the first direction X is greater than the dimension L7 of the first electrode 7 along the first direction X. That is, along the first direction X, the width of the first heavily doped portion 22 is greater than the width of the first electrode 7. This can ensure the alignment allowance between the first electrode 7 and the first heavily doped portion 22, and prevent the first electrode 7 from being incompletely in contact with the first heavily doped portion 22 due to relative misalignment between the first electrode 7 and the first heavily doped portion 22 during the processing. This is beneficial to improving the reliability of the contact between the first electrode 7 and the first heavily doped portion 22.

[0078] As one embodiment of the present invention, it also includes: The second electrode 8 is in contact with the second doped layer 3. The second doped layer 3 includes a second heavily doped portion 32 connected to the second lightly doped portion 31. The second electrode 8 is in contact with the second heavily doped portion 32, and the doping concentration of the second heavily doped portion 32 is greater than 1E19 / cm³. 3 .

[0079] In this embodiment, a second heavily doped portion 32 is provided at the position of the second electrode 8 corresponding to the second doped layer 3, and the doping concentration of the second heavily doped portion 32 is controlled to be greater than 1E19 / cm. 3 Within this concentration range, the second doped portion 32 can ensure a low contact resistance between the second doped portion 32 and the second electrode 8, achieving good ohmic contact between the second electrode 8 and the second doped layer 3, reducing battery electrical losses, and thus further improving battery conversion efficiency.

[0080] In this embodiment, both the first electrode 7 and the second electrode 8 are metal electrodes. For example, both the first electrode 7 and the second electrode 8 are silver electrodes or aluminum electrodes. Of course, the first electrode 7 and the second electrode 8 can also be electrodes made of other conductive materials.

[0081] In a preferred embodiment of the present invention, the first doped layer 2 is an N-type doped layer and the second doped layer 3 is a P-type doped layer. Of course, in some other embodiments, the first doped layer 2 may be a P-type doped layer and the second doped layer 3 may be an N-type doped layer.

[0082] As an embodiment of the present invention, the doping concentration of the second doped portion 32 is greater than 5E19 / cm. 3 .

[0083] In this embodiment, the first doped layer 2 is an N-type doped layer, the second doped layer 3 is a P-type doped layer, and the doping concentration of the second heavily doped portion 32 is greater than 5E19 / cm³. 3 This can further increase the doping concentration of the second doped portion 32, which helps to reduce the contact resistance between the second electrode 8 and the P-type doped layer, improve the contact performance between the P-type doped layer and the second electrode 8, and further improve the battery efficiency.

[0084] As an embodiment of the present invention, the dimension L4 of the second heavily doped portion 32 along the first direction X is greater than the dimension L8 of the second electrode 8 along the first direction X.

[0085] In this embodiment, the dimension L4 of the second heavily doped portion 32 along the first direction X is greater than the dimension L8 of the second electrode 8 along the first direction X. That is, along the first direction X, the width of the second heavily doped portion 32 is greater than the width of the second electrode 8. This can ensure the alignment allowance between the second electrode 8 and the second heavily doped portion 32, and prevent the second electrode 8 from not fully contacting the second heavily doped portion 32 due to relative misalignment between the second electrode 8 and the second heavily doped portion 32 during the processing. This helps to improve the reliability of the contact between the second electrode 8 and the second heavily doped portion 32.

[0086] As an embodiment of the present invention, the ratio of the length L1 of the first lightly doped portion 21 along the first direction X to the length L2 of the first heavily doped portion 22 along the first direction X is 0.006~15.

[0087] In this embodiment, the length L1 of the first lightly doped portion 21 along the first direction X can be less than the length L2 of the first heavily doped portion 22 along the first direction X, or the length L1 of the first lightly doped portion 21 along the first direction X can be greater than the length L2 of the first heavily doped portion 22 along the first direction X, or the length L1 of the first lightly doped portion 21 along the first direction X can be equal to the length L2 of the first heavily doped portion 22 along the first direction X. The ratio of the length L1 of the first lightly doped portion 21 along the first direction X to the length L2 of the first heavily doped portion 22 along the first direction X is controlled to be between 0.006 and 15. This avoids the length of the first lightly doped portion 21 along the first direction X being too small, ensuring good isolation between the first doped layer 2 and the second doped layer 3, and also avoids the first lightly doped portion 21 being too large, which would result in the first heavily doped portion 22 being too small, thus ensuring good contact between the first electrode 7 and the first heavily doped portion 22.

[0088] In this embodiment, the ratio of the length L1 of the first lightly doped portion 21 along the first direction X to the length L2 of the first heavily doped portion 22 along the first direction X can be any value among 0.006, 0.01, 0.1, 0.2, 0.5, 1.0, 1.5, 2, 3, 3.5, 5, 5.5, 6, 6.5, 7, 8, 8.5, 9, 10, 10.5, 11, 12, 12.5, 13, 14, 14.5, and 15.

[0089] As an embodiment of the present invention, the ratio of the length L3 of the second lightly doped portion 31 along the first direction X to the length L4 of the second heavily doped portion 32 along the first direction X is 0.006~15.

[0090] In this embodiment, the length L3 of the second lightly doped portion 31 along the first direction X can be less than the length L4 of the second heavily doped portion 32 along the first direction X, or the length L3 of the second lightly doped portion 31 along the first direction X can be greater than the length L4 of the second heavily doped portion 32 along the first direction X, or the length L3 of the second lightly doped portion 31 along the first direction X can be equal to the length L4 of the second heavily doped portion 32 along the first direction X. The ratio of the length of the second lightly doped portion 31 along the first direction X to the length of the second heavily doped portion 32 along the first direction X is controlled to be between 0.006 and 15. This avoids the length of the second lightly doped portion 31 along the first direction X being too small, ensuring good isolation between the second doped layer 3 and the first doped layer 2, and also avoids the length of the second lightly doped portion 31 along the first direction X being too large, which would result in the length of the second heavily doped portion 32 along the first direction X being too small, thus ensuring good contact between the second electrode 8 and the second heavily doped portion 32.

[0091] In this embodiment, the ratio of the length L3 of the second lightly doped portion 31 along the first direction X to the length L4 of the second heavily doped portion 32 along the first direction X can be any value among 0.006, 0.01, 0.1, 0.2, 0.5, 1.0, 1.5, 2, 3, 3.5, 5, 5.5, 6, 6.5, 7, 8, 8.5, 9, 10, 10.5, 11, 12, 12.5, 13, 14, 14.5, and 15.

[0092] Please refer to Figure 3 As an embodiment of the present invention, the first doped layer 2 includes a first boundary portion 23 located between the first lightly doped portion 21 and the first heavily doped portion 22. Along the first direction X, the doping concentration of the first boundary portion 23 near the first heavily doped portion 22 is greater than the doping concentration of the first boundary portion 23 near the first lightly doped portion 21.

[0093] In this embodiment, a first boundary portion 23 exists between the first lightly doped portion 21 and the first heavily doped portion 22. Along the first direction X, the doping concentration of the first boundary portion 23 near the first heavily doped portion 22 is greater than the doping concentration of the first boundary portion 23 near the other end of the first lightly doped portion 21. That is, the doping concentration of the first boundary portion 23 near the first lightly doped portion 21 is smaller, and the doping concentration of the first boundary portion 23 is greater the closer it is to the first heavily doped portion 22. This helps the first lightly doped portion 21 maintain a lower concentration, achieving a better isolation effect between the second doped layer 3 and the first doped layer 2. At the same time, it helps the first heavily doped portion 22 maintain a higher concentration, which helps maintain a lower contact resistance between the first electrode 7 and the first heavily doped portion 22. Preferably, along the first direction X, the doping concentration of the first boundary portion 23 gradually decreases from the first heavily doped portion 22 to the first lightly doped portion 21. That is, the doping concentration of the first boundary portion 23 is smaller as it gets closer to the first lightly doped portion 21. Therefore, the current transport performance of the part of the first boundary portion 23 closer to the first lightly doped portion 21 is worse. On the other hand, the doping concentration of the first boundary portion 23 is larger as it gets closer to the first heavily doped portion 22. This can better form a concentration difference between the first lightly doped portion 21 and the first heavily doped portion 22, which is more conducive to maintaining a lower concentration of the first lightly doped portion 21 and achieving a better isolation effect between the second doped layer 3 and the first doped layer 2. At the same time, it can maintain a higher concentration of the first heavily doped portion 22, which is conducive to maintaining a lower contact resistance between the first electrode 7 and the first heavily doped portion 22.

[0094] As an embodiment of the present invention, the second doped layer 3 includes a second boundary portion 33 located between the second lightly doped portion 31 and the second heavily doped portion 32. Along the first direction X, the doping concentration of the second boundary portion 33 near the second heavily doped portion 32 is greater than the doping concentration of the second boundary portion 33 near the second lightly doped portion 31.

[0095] In this embodiment, there is a second boundary portion 33 between the second lightly doped portion 31 and the second heavily doped portion 32. Along the first direction X, the doping concentration of the second boundary portion 33 near the second heavily doped portion 32 is greater than the doping concentration of the second boundary portion 33 near the second lightly doped portion 31, which is beneficial to further improve the isolation effect between the second doped layer 3 and the first doped layer 2. Preferably, along the first direction X, the doping concentration of the second boundary portion 33 gradually decreases from the second heavily doped portion 32 to the second lightly doped portion 31. That is, the doping concentration of the second boundary portion 33 is smaller as it gets closer to the second lightly doped portion 31. Therefore, the current transport performance of the second boundary portion 33 closer to the second lightly doped portion 31 is worse. On the other hand, the doping concentration of the second boundary portion 33 is larger as it gets closer to the second heavily doped portion 32. Therefore, the current transport performance of the second boundary portion 33 closer to the second heavily doped portion 32 is better. This can better form a concentration difference between the second lightly doped portion 31 and the second heavily doped portion 32, which is more conducive to ensuring that the second lightly doped portion 31 maintains a lower concentration and achieving a better isolation effect between the second doped layer 3 and the first doped layer 2. At the same time, it can maintain a higher concentration of the second heavily doped portion 32, which is conducive to maintaining a lower contact resistance between the second electrode 8 and the second heavily doped portion 32.

[0096] As an embodiment of the present invention, the length W1 of the first boundary portion 23 along the first direction X is 0.1~5 micrometers.

[0097] In this embodiment, the length W1 of the first boundary portion 23 along the first direction X is controlled to be 0.1~5 micrometers. This can not only make it easier to form a concentration difference between the first lightly doped portion 21 and the first heavily doped portion 22, but also help to ensure that the first lightly doped portion 21 maintains a low concentration, thus achieving a better isolation effect between the second doped layer 3 and the first doped layer 2. At the same time, it can keep the first heavily doped portion 22 at a high concentration, which helps to maintain a low contact resistance between the first electrode 7 and the first heavily doped portion 22.

[0098] In this embodiment, the length W1 of the first boundary portion 23 along the first direction X can be any value among 0.1 micrometers, 0.2 micrometers, 0.3 micrometers, 0.5 micrometers, 0.8 micrometers, 0.9 micrometers, 1 micrometer, 1.1 micrometers, 1.2 micrometers, 1.5 micrometers, 2 micrometers, 2.1 micrometers, 2.3 micrometers, 2.5 micrometers, 3 micrometers, 3.1 micrometers, 3.5 micrometers, 3.8 micrometers, 3.9 micrometers, 4 micrometers, 4.1 micrometers, 4.2 micrometers, 4.5 micrometers, 4.6 micrometers, 4.8 micrometers, and 5 micrometers.

[0099] As an embodiment of the present invention, the length W2 of the second boundary portion 33 along the first direction X is 0.1 to 5 micrometers.

[0100] In this embodiment, controlling the length W2 of the second boundary portion 33 along the first direction X to be 0.1~5 micrometers can better form a concentration difference between the second lightly doped portion 31 and the second heavily doped portion 32, which is more conducive to ensuring that the second lightly doped portion 31 maintains a low concentration and achieving a better isolation effect between the second doped layer 3 and the first doped layer 2. At the same time, it can maintain a high concentration of the second heavily doped portion 32, which is conducive to maintaining a low contact resistance between the second electrode 8 and the second heavily doped portion 32.

[0101] In this embodiment, the length W2 of the second boundary portion 33 along the first direction X can be any value selected from 0.1 μm, 0.2 μm, 0.3 μm, 0.5 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.5 μm, 2 μm, 2.1 μm, 2.3 μm, 2.5 μm, 3 μm, 3.1 μm, 3.5 μm, 3.8 μm, 3.9 μm, 4 μm, 4.1 μm, 4.2 μm, 4.5 μm, 4.6 μm, 4.8 μm, and 5 μm. The length W1 of the first boundary portion 23 along the first direction X and the length W2 of the second boundary portion 33 along the first direction X can be the same or different.

[0102] In one embodiment of the present invention, both the first lightly doped portion 21 and the first heavily doped portion 22 are provided with holes, and the number of holes per unit area of ​​the first lightly doped portion 21 is less than the number of holes per unit area of ​​the first heavily doped portion 22.

[0103] In this embodiment, the number of pores per unit area of ​​the first lightly doped portion 21 is less than the number of pores per unit area of ​​the first heavily doped portion 22. That is, under the same unit area, the number of pores per unit area of ​​the first lightly doped portion 21 is less than the number of pores per unit area of ​​the first heavily doped portion 22, which is more conducive to improving the passivation effect of the first lightly doped portion 21 and reducing recombination loss.

[0104] In one embodiment of the present invention, both the first lightly doped portion 21 and the first heavily doped portion 22 are provided with holes, and the average maximum radial dimension of the holes in the first lightly doped portion 21 is smaller than the average maximum radial dimension of the first heavily doped portion 22.

[0105] In this embodiment, the maximum radial dimension of the holes in the first lightly doped portion 21 is the same as the maximum radial dimension of the holes in the first heavily doped portion 22. The average maximum radial dimension of the holes in the first lightly doped portion 21 is the average of the maximum radial dimensions of all holes within a unit area of ​​the first lightly doped portion 21, and the average maximum radial dimension of the holes in the first heavily doped portion 22 is the average of the maximum radial dimensions of all holes within a unit area of ​​the first heavily doped portion 22. Controlling the average maximum radial dimension of the holes in the first lightly doped portion 21 to be smaller than the average maximum radial dimension of the first heavily doped portion 22 helps to further improve the passivation effect of the first lightly doped portion 21 and reduce recombination losses.

[0106] As an embodiment of the present invention, both the second lightly doped portion 31 and the second heavily doped portion 32 are provided with holes, and the number of holes per unit area of ​​the second lightly doped portion 31 is less than the number of holes per unit area of ​​the second heavily doped portion 32.

[0107] In this embodiment, the number of pores per unit area of ​​the second lightly doped portion 31 is less than the number of pores per unit area of ​​the second heavily doped portion 32. That is, under the same unit area, the number of pores per unit area of ​​the second lightly doped portion 31 is less than the number of pores per unit area of ​​the second heavily doped portion 32, which is more conducive to improving the passivation effect of the second lightly doped portion 31 and reducing recombination loss.

[0108] As an embodiment of the present invention, both the second lightly doped portion 31 and the second heavily doped portion 32 are provided with holes, and the average maximum radial dimension of the holes in the second lightly doped portion 31 is smaller than the average maximum radial dimension of the second heavily doped portion 32.

[0109] In this embodiment, the maximum radial dimension of the pores in the second lightly doped portion 31 is the same as the maximum radial dimension of the pores in the second heavily doped portion 32. The average maximum radial dimension of the pores in the second lightly doped portion 31 is the average of the maximum radial dimensions of all pores within a unit area of ​​the second lightly doped portion 31, and the average maximum radial dimension of the pores in the second heavily doped portion 32 is the average of the maximum radial dimensions of all pores within a unit area of ​​the second heavily doped portion 32. Controlling the average maximum radial dimension of the pores in the second lightly doped portion 31 to be smaller than the average maximum radial dimension of the second heavily doped portion 32 can further improve the passivation effect of the second lightly doped portion 31 and reduce recombination losses.

[0110] Please refer to the reference. Figure 2As an embodiment of the present invention, the first lightly doped portion 21 includes a first portion 211 connected to the first heavily doped portion 22, and the isolation layer 6 includes a first isolation portion 61 connected to the first tunneling layer 4. The first isolation portion 61 is bent relative to the first tunneling layer 4 in a direction away from the back surface 101, and the first isolation portion 61 is located between the first portion 211 and the second lightly doped portion 31.

[0111] In this embodiment, the materials of the first isolation portion 61 and the first tunneling layer 4 can be the same or different. The first isolation portion 61 and the first tunneling layer 4 can be integrally formed or have a separate structure. The first isolation portion 61 extends along the thickness direction Z of the silicon substrate 1. The first lightly doped portion 21 includes a first portion 211 connected to the first heavily doped portion 22. The first isolation portion 61 isolates the first portion 211 from the second lightly doped portion 31, thereby achieving isolation between the second doped layer 3 and the first doped layer 2.

[0112] As an embodiment of the present invention, the first lightly doped portion 21 includes a second portion 212 connected to the first portion 211 and bent relative to the first portion 211 in a direction away from the back surface 101, and the first isolation portion 61 is also located between the second portion 212 and the second lightly doped portion 31.

[0113] In this embodiment, the first lightly doped portion 21 further includes a second portion 212, which can further increase the area of ​​the first lightly doped portion 21 and improve the passivation effect of the first lightly doped portion 21. The first isolation portion 61 is located between the first portion 211 and the second lightly doped portion 31, and also between the second portion 212 and the second lightly doped portion 31. Thus, the first isolation portion 61 isolates the first portion 211 from the second lightly doped portion 31, and also isolates the second portion 212 from the second lightly doped portion 31, which can further improve the isolation effect between the second doped layer 3 and the first doped layer 2.

[0114] As an embodiment of the present invention, the first lightly doped portion 21 further includes a third portion 213 connected to the second portion 212. The third portion 213 is bent relative to the second portion 212. The third portion 213 extends along the first direction X toward the second doped layer 3, and the orthogonal projection of the third portion 213 on the back surface 101 at least covers the first isolation portion 61.

[0115] In this embodiment, the first lightly doped portion 21 further includes a third portion 213, which can further increase the area of ​​the first lightly doped portion 21 and further improve the passivation effect of the first lightly doped portion 21; moreover, the orthogonal projection of the third portion 213 on the back surface 101 at least covers the first isolation portion 61, and the third portion 213 of the first lightly doped portion 21 can reflect the sunlight emitted from the position of the first isolation portion 61 on the back surface 101 back into the silicon substrate 1, increase the absorption of sunlight by the silicon substrate 1, and further improve the battery efficiency.

[0116] As an embodiment of the present invention, the thickness D1 of the first isolation portion 61 is 1~20 nanometers.

[0117] In this embodiment, the thickness D1 of the first isolation portion 61 is the dimension of the first isolation portion 61 along the first direction X. The thickness of the first isolation portion 61 is controlled to be 1~20 nanometers to ensure good isolation effect of the first isolation portion 61.

[0118] The thickness D1 of the first isolation portion 61 can be any value from 1 to 20 nanometers. For example, the thickness of the first isolation portion 61 can be any value from 1.1 nanometers, 1.3 nanometers, 1.5 nanometers, 1.7 nanometers, 1.9 nanometers, 2.0 nanometers, 2.3 nanometers, 2.5 nanometers, 2.6 nanometers, 3 nanometers, 3.3 nanometers, 3.5 nanometers, 4.0 nanometers, 4.1 nanometers, 4.3 nanometers, 4.8 nanometers, 5.0 nanometers, 5.6 nanometers, 6.2 nanometers, 7 nanometers, 7.4 nanometers, 8.0 nanometers, 8.5 nanometers, 9 nanometers, 10 nanometers, 11 nanometers, 13 nanometers, 15 nanometers, 18 nanometers, and 20 nanometers.

[0119] In a preferred embodiment of the present invention, the thickness D1 of the first isolation portion 61 is 1-10 nanometers. More preferably, the thickness of the first isolation portion 61 is 1-5 nanometers. This can further ensure the good isolation effect of the first isolation portion 61, and when the battery cell is blocked, it is beneficial for the first isolation portion 61 to form a leakage current channel between the first lightly doped portion 21 and the second lightly doped portion 31, which can reduce the risk of hot spots and improve the safety and reliable power generation of the battery.

[0120] As an embodiment of the present invention, the ratio of the thickness D1 of the first isolation portion 61 to the thickness D2 of the first tunneling layer 4 is 1 to 10.

[0121] In this embodiment, the thickness D2 of the first tunneling layer 4 is the dimension of the first tunneling layer 4 along the thickness direction Z of the silicon substrate 1. The ratio of the thickness D1 of the first isolation portion 61 to the thickness D2 of the first tunneling layer 4 can be any value among 1, 1.1, 1.3, 1.5, 1.7, 1.9, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, and 10.

[0122] In this embodiment, the ratio of the thickness D1 of the first isolation part 61 to the thickness D2 of the first tunneling layer 4 is controlled to be 1~10, which can achieve a good isolation effect of the first isolation part 61 and ensure a good tunneling passivation effect of the first tunneling layer 4.

[0123] As an embodiment of the present invention, the ratio of the thickness D1 of the first isolation portion 61 to the thickness of the first tunneling layer D2 is 1.1 to 5.

[0124] In this embodiment, the ratio of the thickness D1 of the first isolation section 61 to the thickness D2 of the first tunneling layer 4 is further controlled to be 1.1 to 5, so as to achieve a good isolation effect of the first isolation section 61.

[0125] As an embodiment of the present invention, the first isolation part 61 and the first tunneling layer 4 are an integral structure.

[0126] In this embodiment, the first isolation part 61 and the first tunneling layer 4 are an integral structure, which facilitates the simultaneous thermal oxidation growth or deposition of the first isolation part 61 and the first tunneling layer 4, thereby simplifying the production process and reducing production costs.

[0127] As an embodiment of the present invention, the first isolation portion 61 is a stack of one or more of the following: silicon oxide layer, aluminum oxide layer, silicon nitride layer, and silicon oxynitride layer.

[0128] The first isolation portion 61 is one of silicon oxide layer, aluminum oxide layer, silicon nitride layer, and silicon oxynitride layer. The first isolation portion 61 may also be a stack of at least two of silicon oxide layer, aluminum oxide layer, silicon nitride layer, and silicon oxynitride layer.

[0129] As an embodiment of the present invention, the isolation layer 6 includes a second isolation portion 62 connected to the first isolation portion 61, and the second isolation portion 62 is located between the third portion 213 and the second lightly doped portion 31.

[0130] In this embodiment, the second isolation portion 62 is located between the third portion 213 and the second doped layer 3 to isolate the third portion 213 and the second doped layer 3, which can further improve the isolation effect between the second doped layer 3 and the first doped layer 2. The orthographic projection of the third portion 213 on the back surface 101 and the orthographic projection of the second doped layer 3 on the back surface 101 may or may not intersect.

[0131] As an embodiment of the present invention, the thickness D3 of the second isolation portion 62 along the thickness direction Z of the silicon substrate 1 is greater than the thickness D1 of the first isolation portion 61 along the first direction X.

[0132] In this embodiment, the thickness of the second isolation portion 62 along the thickness direction Z of the silicon substrate 1 is greater than the thickness of the first isolation portion 61 along the first direction X, which helps to improve the isolation effect of the second isolation portion 62.

[0133] As an embodiment of the present invention, the second isolation portion 62 is a stack of one or more of the following: silicon oxide layer, aluminum oxide layer, silicon oxynitride layer, silicon nitride layer, borosilicate glass, and phosphosilicate glass.

[0134] The materials of the second isolation portion 62 and the first isolation portion 61 can be the same or different. Preferably, the second isolation portion 62 is borosilicate glass or phosphosilicate glass, which allows the second isolation portion 62 to conduct the first doped layer 2 and the second doped layer 3 when the back contact battery 100 is shaded, so that the current can be transmitted through the second isolation portion 62. This prevents the shaded battery from becoming a load and consuming the energy generated by other illuminated battery cells, thereby reducing the risk of hot spots.

[0135] As an embodiment of the present invention, the refractive index of the second isolation portion 62 is greater than that of the first isolation portion 61.

[0136] In this embodiment, since the second isolation portion 62 is located between the first doped layer 2 and the second doped layer 3, the refractive index of the second isolation portion 62 is controlled to be greater than that of the first isolation portion 61. This is beneficial for the second isolation portion 62 to reflect the sunlight emitted from the back side 101 back into the silicon substrate 1, thereby improving the utilization rate of sunlight.

[0137] As an embodiment of the present invention, the thickness D3 of the second isolation portion 62 is 5 to 100 nanometers.

[0138] In this embodiment, the thickness of the second isolation portion 62 is the dimension of the second isolation portion 62 along the thickness direction Z of the silicon substrate 1. The thickness of the second isolation portion 62 is controlled to be 5~100 nanometers to ensure good isolation effect of the second isolation portion 62.

[0139] In this embodiment, the thickness D3 of the second isolation portion 62 can be any value among 5 nanometers, 10 nanometers, 15 nanometers, 20 nanometers, 25 nanometers, 30 nanometers, 35 nanometers, 40 nanometers, 45 nanometers, 50 nanometers, 55 nanometers, 60 nanometers, 65 nanometers, 70 nanometers, 75 nanometers, 80 nanometers, 85 nanometers, 90 nanometers, 95 nanometers, and 100 nanometers.

[0140] Please refer to Figure 4 As an embodiment of the present invention, the surface of the second isolation portion 62 facing away from the silicon substrate 1 is provided with a textured structure 621.

[0141] In this embodiment, the textured structure 621 can be a regular pyramid structure or an inverted pyramid structure. By providing the textured structure 621 on the surface of the second isolation portion 62 away from the silicon substrate 1, the textured structure 621 can reflect sunlight emitted from the back side 101 back into the silicon substrate 1, increasing the optical path of sunlight within the silicon substrate 1 and thus improving the utilization rate of sunlight.

[0142] Please refer to Figure 4 As one embodiment of the present invention, it further includes: Barrier layer 12 is disposed in at least a portion of the region between isolation layer 6 and second lightly doped portion 31.

[0143] In this embodiment, at least a portion of the area between the isolation layer 6 and the second lightly doped portion 31 is provided with a barrier layer 12. Specifically, the barrier layer 12 and the first isolation portion 61 are provided simultaneously between the first doped layer 2 and the second lightly doped portion 31. By using the barrier layer 12 and the first isolation portion 61 to jointly isolate the first doped layer 2 and the second doped layer 3, the isolation effect between the first doped layer 2 and the second doped layer 3 can be further improved.

[0144] In this embodiment, the barrier layer 12 may be provided in the entire area between the isolation layer 6 and the second lightly doped portion 31, or the barrier layer 12 may be provided in only a portion of the area between the isolation layer 6 and the second lightly doped portion 31. Specifically, the barrier layer 12 is provided in at least a portion of the area between the first isolation portion 61 and the second lightly doped portion 31.

[0145] As an embodiment of the present invention, the barrier layer 12 is one or a combination of at least two of borosilicate glass, phosphosilicate glass, silicon oxide, silicon nitride, and silicon oxynitride.

[0146] In this embodiment, when the second doped layer 3 is a boron-doped layer, the barrier layer 12 is borosilicate glass, and the barrier layer 12 can be formed simultaneously with the boron doping of the second lightly doped portion 31; when the second doped layer 3 is a phosphorus-doped layer, the barrier layer 12 is phosphosilicate glass, and the barrier layer 12 can be formed simultaneously with the phosphorus doping of the second lightly doped portion 31. Additionally, in other embodiments, the barrier layer 12 can also be one or a combination of silicon oxide, silicon nitride, and silicon oxynitride.

[0147] As an embodiment of the present invention, the back contact battery 100 further includes: A passivation layer 9 covers the first doped layer 2 and the second doped layer 3. The first electrode 7 passes through the passivation layer 9 and contacts the first heavily doped part 22. The second electrode 8 passes through the passivation layer 9 and contacts the second heavily doped part 32.

[0148] In this embodiment, the passivation layer 9 covers the entire back surface 101 of the silicon substrate 1, and the first doped layer 2 and the second doped layer 3 are completely covered by the passivation layer 9, which helps to further enhance the passivation effect of the back surface 101. The passivation layer 9 can be one or a stack of at least two of the following: silicon oxide layer, aluminum oxide layer, silicon nitride layer, and silicon oxynitride layer.

[0149] 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.

[0150] 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.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] 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.

[0157] 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: Silicon substrate, the silicon substrate including a back side; A first doped layer and a second doped layer are disposed on the back side, the second doped layer and the first doped layer having opposite doping types, and the second doped layer and the first doped layer are alternately disposed along a first direction; the first doped layer includes a first lightly doped portion, the second doped layer includes a second lightly doped portion, the first lightly doped portion and the second lightly doped portion are disposed adjacent to each other, and the doping concentration of both the first lightly doped portion and the second lightly doped portion is less than or equal to 1E19 / cm³. 3 ; A first tunneling layer is disposed between the silicon substrate and the first doped layer; A second tunneling layer is disposed between the silicon substrate and the second doped layer; and An isolation layer is disposed between the first lightly doped portion and the second lightly doped portion.

2. The back contact battery according to claim 1, characterized in that, The doping concentrations of the first lightly doped portion and the second lightly doped portion are 1E14 / cm. 3 ~1E19 / cm 3 .

3. The back contact battery according to claim 1, characterized in that, Also includes: A first electrode is disposed on the first doped layer, the first doped layer including a first heavily doped portion connected to the first lightly doped portion, the first electrode being in contact with the first heavily doped portion, and the doping concentration of the first heavily doped portion being greater than 1E19 / cm. 3 .

4. The back contact battery according to claim 3, characterized in that, The doping concentration of the first heavily doped region is greater than 1E20 / cm 3 .

5. The back contact battery according to claim 3, characterized in that, The dimension of the first heavily doped portion along the first direction is greater than the dimension of the first electrode along the first direction.

6. The back contact battery according to claim 1, characterized in that, The ratio of the doping concentration of the first lightly doped portion to the doping concentration of the second lightly doped portion is 1 to 100; or, the ratio of the doping concentration of the second lightly doped portion to the doping concentration of the first lightly doped portion is 1 to 100.

7. The back contact battery according to claim 3, characterized in that, Also includes: The second electrode is in contact with the second doped layer, the second doped layer including a second heavily doped portion connected to the second lightly doped portion, the second electrode being in contact with the second heavily doped portion, and the doping concentration of the second heavily doped portion being greater than 1E19 / cm². 3 .

8. The back contact battery according to claim 7, characterized in that, The first doped layer is an N-type doped layer, and the second doped layer is a P-type doped layer; the doping concentration of the second heavily doped region is greater than 5E19 / cm³. 3 .

9. The back contact battery according to claim 3, characterized in that, The ratio of the length of the first lightly doped portion along the first direction to the length of the first heavily doped portion along the first direction is 0.006~15.

10. The back contact battery according to claim 7, characterized in that, The ratio of the length of the second lightly doped portion along the first direction to the length of the second heavily doped portion along the first direction is 0.006~15.

11. The back contact battery according to claim 3, characterized in that, The first doped layer includes a first boundary portion located between the first lightly doped portion and the first heavily doped portion. Along the first direction, the doping concentration of the first boundary portion near the first heavily doped portion is greater than the doping concentration of the first boundary portion near the first lightly doped portion.

12. The back contact battery according to claim 7, characterized in that, The second doped layer includes a second boundary portion located between the second lightly doped portion and the second heavily doped portion. Along the first direction, the doping concentration of the second boundary portion near the second heavily doped portion is greater than the doping concentration of the second boundary portion near the second lightly doped portion.

13. The back contact battery according to claim 11, characterized in that, The length of the first boundary portion along the first direction is 0.1 to 5 micrometers.

14. The back contact battery according to claim 12, characterized in that, The length of the second boundary portion along the first direction is 0.1 to 5 micrometers.

15. The back contact battery according to claim 3, characterized in that, Both the first lightly doped portion and the first heavily doped portion are provided with pores, and the number of pores per unit area of ​​the first lightly doped portion is less than the number of pores per unit area of ​​the first heavily doped portion.

16. The back contact battery according to claim 3, characterized in that, Both the first lightly doped portion and the first heavily doped portion are provided with holes, and the average maximum radial dimension of the holes in the first lightly doped portion is smaller than the average maximum radial dimension of the first heavily doped portion.

17. The back contact battery according to claim 7, characterized in that, Both the second lightly doped portion and the second heavily doped portion are provided with pores, and the number of pores per unit area of ​​the second lightly doped portion is less than the number of pores per unit area of ​​the second heavily doped portion.

18. The back contact battery according to claim 7, characterized in that, Both the second lightly doped portion and the second heavily doped portion are provided with holes, and the average maximum radial dimension of the holes in the second lightly doped portion is smaller than the average maximum radial dimension of the second heavily doped portion.

19. The back contact battery according to claim 7, characterized in that, The dimension of the second heavily doped portion along the first direction is greater than the dimension of the second electrode along the first direction.

20. The back contact battery according to claim 3, characterized in that, The first lightly doped portion includes a first portion connected to the first heavily doped portion, the isolation layer includes a first isolation portion connected to the first tunneling layer, the first isolation portion is bent away from the back side relative to the first tunneling layer, and the first isolation portion is located between the first portion and the second lightly doped portion.

21. The back contact battery according to claim 20, characterized in that, The first lightly doped portion includes a second portion connected to the first portion and bent away from the back side relative to the first portion, and the first isolation portion is also located between the second portion and the second lightly doped portion.

22. The back contact battery according to claim 21, characterized in that, The first lightly doped portion further includes a third portion connected to the second portion, the third portion being bent relative to the second portion, the third portion extending along the first direction toward the second doped layer, and the orthogonal projection of the third portion on the back side at least covering the first isolation portion.

23. The back contact battery according to claim 22, characterized in that, The isolation layer includes a second isolation portion connected to the first isolation portion, the second isolation portion being located between the third portion and the second lightly doped portion.

24. The back contact battery according to claim 23, characterized in that, The thickness of the second isolation portion along the thickness direction of the silicon substrate is greater than the thickness of the first isolation portion along the first direction.

25. The back contact battery according to claim 20, characterized in that, The first isolation section and the first tunnel layer are an integral structure.

26. The back contact battery according to claim 20, characterized in that, The first isolation portion is a stack of one or more of the following: silicon oxide layer, aluminum oxide layer, silicon nitride layer, and silicon oxynitride layer.

27. The back contact battery according to claim 23, characterized in that, The second isolation layer is a stack of one or more of the following: silicon oxide layer, aluminum oxide layer, silicon oxynitride layer, silicon nitride layer, borosilicate glass, and phosphosilicate glass.

28. The back contact battery according to claim 23, characterized in that, The refractive index of the second isolation part is greater than that of the first isolation part.

29. The back contact battery according to claim 23, characterized in that, The thickness of the second isolation part is 5~100 nanometers.

30. The back contact battery according to claim 20, characterized in that, The thickness of the first isolation part is 1~20 nanometers.

31. The back contact battery according to claim 20, characterized in that, The ratio of the thickness of the first isolation section to the thickness of the first tunneling layer is 1 to 10.

32. The back contact battery according to claim 31, characterized in that, The ratio of the thickness of the first isolation section to the thickness of the first tunneling layer is 1.1 to 5.

33. The back contact battery according to claim 20, characterized in that, Also includes: A barrier layer is disposed in at least a portion of the region between the first isolation portion and the second lightly doped portion.

34. The back contact battery according to claim 33, characterized in that, The barrier layer is one or a combination of at least two of borosilicate glass, phosphosilicate glass, silicon oxide, silicon nitride, and silicon oxynitride.

35. The back contact battery according to claim 23, characterized in that, The surface of the second isolation portion facing away from the silicon substrate is provided with a textured structure.

36. The back contact battery according to claim 1, characterized in that, The first tunneling layer and the second tunneling layer are one or more of the following: silicon oxide layer, aluminum oxide layer, silicon nitride layer, and silicon oxynitride layer.

37. The back contact battery according to claim 1, characterized in that, The first doped layer and the second doped layer are one or a combination of at least two of the following: a doped polycrystalline silicon layer, a doped microcrystalline silicon layer, or a doped nanocrystalline silicon layer.

38. The back contact battery according to claim 7, characterized in that, Also includes: A passivation layer covers the first doped layer and the second doped layer. The first electrode passes through the passivation layer and contacts the first heavily doped portion, and the second electrode passes through the passivation layer and contacts the second heavily doped portion.

39. A battery assembly, characterized in that, Includes the back contact battery as described in any one of claims 1 to 38.

40. A photovoltaic system, characterized in that, Includes the battery assembly as described in claim 39.

Images