Photovoltaic cell, manufacturing method thereof and photovoltaic module

Abstract

The embodiment of the invention relates to the photovoltaic field, and provides a photovoltaic cell and a manufacturing method thereof, and a photovoltaic module, and the photovoltaic cell comprises a substrate and a tunneling layer located on the back surface of the substrate. The nitrogen-phosphorus co-doped polycrystalline silicon layer is positioned on one side, far away from the substrate, of the tunneling layer; the diffusion barrier layer is positioned on one side, far away from the tunneling layer, of the nitrogen-phosphorus co-doped polycrystalline silicon layer; and the phosphorus-doped polycrystalline silicon layer is positioned on one side, far away from the nitrogen-phosphorus co-doped polycrystalline silicon layer, of the diffusion barrier layer. The embodiment of the invention is at least beneficial to improving the photoelectric conversion efficiency of the photovoltaic cell.

Description

Technical Field

[0001] The present disclosure relates to the photovoltaic field, and in particular to a photovoltaic cell and a manufacturing method thereof, and a photovoltaic module. Background Art

[0002] As fossil energy is gradually depleted, photovoltaic cells are becoming more and more widely used as a new energy alternative. Photovoltaic cells are devices that convert sunlight into electrical energy. Photovoltaic cells use the principle of photovoltaics to generate carriers, and then use electrodes to lead the carriers out, thereby facilitating the effective use of electrical energy.

[0003] The current photovoltaic cells mainly include IBC cells (Interdigitated Back Contact), TOPCON (Tunnel Oxide Passivated Contact), PERC cells (Passivated emitter and real cell) and heterojunction cells, etc. The photoelectric conversion efficiency of solar cells is improved by reducing optical losses and reducing the recombination of photogenerated carriers on the surface and in the body of the silicon substrate through different film layer settings and functional limitations.

[0004] However, the photoelectric conversion efficiency of current photovoltaic cells still needs to be improved. Summary of the invention

[0005] The embodiments of the present disclosure provide a photovoltaic cell and a manufacturing method thereof, and a photovoltaic module, which are at least beneficial to improving the photoelectric conversion efficiency of the photovoltaic cell.

[0006] According to some embodiments of the present disclosure, on one hand, the embodiments of the present disclosure provide a photovoltaic cell, comprising: a substrate and a tunneling layer located on the back side of the substrate; a nitrogen-phosphorus co-doped polysilicon layer located on a side of the tunneling layer away from the substrate; a diffusion barrier layer located on a side of the nitrogen-phosphorus co-doped polysilicon layer away from the tunneling layer; and a phosphorus-doped polysilicon layer located on a side of the diffusion barrier layer away from the nitrogen-phosphorus co-doped polysilicon layer.

[0007] In some embodiments, the doping concentration of nitrogen in the nitrogen-phosphorus co-doped polysilicon layer is 1×10 17 atom / cm 3 ~1×10 20 atom / cm 3 .

[0008] In some embodiments, along the direction from the tunneling layer to the substrate, the doping concentration of phosphorus in the nitrogen-phosphorus co-doped polysilicon layer gradually decreases, and the doping concentration of phosphorus in the nitrogen-phosphorus co-doped polysilicon layer is 0.1×1017 atom / cm 3 ~5×10 21 atom / cm 3 .

[0009] In some embodiments, the material of the diffusion barrier layer is silicon oxynitride; and / or, along the direction from the tunnel layer to the substrate, the thickness of the diffusion barrier layer is 0.5 nm to 10 nm.

[0010] In some embodiments, along a direction from the tunneling layer to the substrate, a thickness of the nitrogen-phosphorus co-doped polysilicon layer is less than a thickness of the phosphorus-doped polysilicon layer.

[0011] According to some embodiments of the present disclosure, on the other hand, the embodiments of the present disclosure further provide a method for manufacturing a photovoltaic cell, including: providing a substrate, forming a tunneling layer on the back side of the substrate; forming a first silicon material layer on a side of the tunneling layer away from the substrate; performing nitrogen doping treatment on the first silicon material layer to convert the first silicon material layer into a nitrogen-doped layer; forming a diffusion barrier film on a side of the nitrogen-doped layer away from the tunneling layer; forming a second silicon material layer on a side of the diffusion barrier film away from the nitrogen-doped layer; performing phosphorus doping treatment on the nitrogen-doped layer, the diffusion barrier film and the second silicon material layer as a whole to convert the nitrogen-doped layer into a nitrogen-phosphorus co-doped polycrystalline silicon layer, convert the diffusion barrier film into a diffusion barrier layer, and convert the second silicon material layer into a phosphorus-doped polycrystalline silicon layer.

[0012] In some embodiments, the step of performing the nitrogen doping treatment on the first silicon material layer includes: treating the first silicon material layer with plasma ammonia gas so that nitrogen and hydrogen elements are doped into the first silicon material layer.

[0013] In some embodiments, in the step of performing the phosphorus doping treatment, based on the barrier effect of the diffusion barrier film on phosphorus, the doping concentration of phosphorus in the nitrogen-doped layer closer to the substrate is lower.

[0014] In some embodiments, the first silicon material layer and the second silicon material layer are both amorphous silicon; the step of performing the phosphorus doping treatment includes: forming a phosphorus doping source layer on the side of the second silicon material layer away from the diffusion barrier film; performing annealing treatment to diffuse the phosphorus element in the phosphorus doping source layer into the second silicon material layer, the diffusion barrier film and the nitrogen-doped layer in sequence, and converting the first silicon material layer and the second silicon material layer into polycrystalline silicon.

[0015] According to some embodiments of the present disclosure, on the other hand, the embodiments of the present disclosure further provide a photovoltaic module, comprising: a cell string, formed by connecting a plurality of photovoltaic cells as described in any one of the above items, or formed by connecting a plurality of photovoltaic cells formed by any one of the manufacturing methods described in any one of the above items; a packaging film, used to cover the surface of the cell string; and a cover plate, used to cover the surface of the packaging film facing away from the cell string.

[0016] The technical solution provided by the embodiments of the present disclosure has at least the following advantages: On the one hand, the nitrogen-phosphorus co-doped polysilicon layer closest to the tunneling layer is designed to contain two doping elements, nitrogen and phosphorus. Compared with the polysilicon layer not doped with nitrogen, it is beneficial to increase the optical band gap of the nitrogen-phosphorus co-doped polysilicon layer by introducing nitrogen, and reduce the parasitic absorption of the nitrogen-phosphorus co-doped polysilicon layer to light in the near-infrared band; on the other hand, the nitrogen doped in the nitrogen-phosphorus co-doped polysilicon layer can be enriched at the interface where the tunneling layer and the nitrogen-phosphorus co-doped polysilicon layer contact, and the nitrogen element can capture hydrogen, which is beneficial to improve the passivation effect of the nitrogen-phosphorus co-doped polysilicon layer on the back side; on the other hand, the phosphorus-doped polysilicon layer is designed to be connected to the electrode in the photovoltaic cell. Compared with the nitrogen-phosphorus co-doped polysilicon layer, the phosphorus-doped polysilicon layer has a lower resistivity, which can further reduce the contact resistance between the electrode and the phosphorus-doped polysilicon layer, so as to improve the collection efficiency of the electrode for carriers; on the other hand, it is beneficial to block the diffusion of the material constituting the electrode toward the substrate by means of the diffusion barrier layer, and effectively reduce the high-density defect state caused by the direct contact between the material constituting the electrode and the substrate. In this way, the cooperation of multiple aspects is conducive to improving the photoelectric conversion efficiency of photovoltaic cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings, and these exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise specified, the pictures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the traditional technology, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A schematic diagram of a partial cross-sectional structure of a photovoltaic cell provided in one embodiment of the present disclosure; Figure 2 Another partial cross-sectional structural schematic diagram of a photovoltaic cell provided in one embodiment of the present disclosure; Figure 3 A schematic diagram of a partial cross-sectional structure of an initial substrate provided in a method for manufacturing a photovoltaic cell provided in another embodiment of the present disclosure; Figure 4 A schematic diagram of a partial cross-sectional structure of a substrate provided in a method for manufacturing a photovoltaic cell provided in another embodiment of the present disclosure; Figure 5 A schematic diagram of a partial cross-sectional structure in which a tunneling layer and a first silicon material layer are formed on a substrate in a method for manufacturing a photovoltaic cell provided by another embodiment of the present disclosure; Figure 6 For Figure 5 A schematic diagram of a local cross-sectional structure formed after nitrogen doping treatment based on the structure shown; Figure 7 For Figure 6 A schematic diagram of a partial cross-sectional structure after a diffusion barrier film and a second silicon material layer are formed on the basis of the structure shown; Figure 8 For Figure 7 A schematic diagram of a local cross-sectional structure formed after phosphorus doping treatment based on the structure shown; Fig. 9 A schematic diagram of a partial three-dimensional structure of a photovoltaic assembly provided by another embodiment of the present disclosure; Fig.10 for Fig. 9 A schematic diagram of a cross-sectional structure along the cross-sectional direction MM1.

[0019] Description of reference numerals: 100, substrate; 110, back side; 120, initial substrate; 130, front side; 140, first laser zone; 101, tunneling layer; 102, nitrogen-phosphorus co-doped polysilicon layer; 12, first silicon material layer; 122, nitrogen-doped layer; 103, diffusion barrier layer; 113, diffusion barrier film; 104, phosphorus-doped polysilicon layer; 114, second silicon material layer; 106, electrode; 107, boron diffusion layer; 108, passivation layer; 118, aluminum oxide layer; 128, silicon nitride layer; 40, photovoltaic cell; 41, encapsulation film; 42, cover plate; 402, conductive tape. DETAILED DESCRIPTION

[0020] As known from the background technology, the photoelectric conversion efficiency of photovoltaic cells needs to be improved.

[0021] The present disclosure provides a photovoltaic cell and a manufacturing method thereof, and a photovoltaic module. In the photovoltaic cell, on the one hand, the nitrogen-phosphorus co-doped polycrystalline silicon layer closest to the tunneling layer is designed to contain two doping elements, nitrogen and phosphorus. Compared with the polycrystalline silicon layer not doped with nitrogen, it is beneficial to increase the optical band gap of the nitrogen-phosphorus co-doped polycrystalline silicon layer by introducing nitrogen, and at the same time reduce the parasitic absorption of light in the near-infrared band by the nitrogen-phosphorus co-doped polycrystalline silicon layer; on the other hand, the nitrogen doped in the nitrogen-phosphorus co-doped polycrystalline silicon layer can be enriched at the interface where the tunneling layer contacts the nitrogen-phosphorus co-doped polycrystalline silicon layer, and the nitrogen element can The capture of hydrogen elements is beneficial to improve the passivation effect of the nitrogen-phosphorus co-doped polysilicon layer on the back side; on the other hand, the phosphorus-doped polysilicon layer is designed to be connected to the electrode in the photovoltaic cell. Compared with the nitrogen-phosphorus co-doped polysilicon layer, the phosphorus-doped polysilicon layer has a lower resistivity, which can further reduce the contact resistance between the electrode and the phosphorus-doped polysilicon layer to improve the electrode's collection efficiency of carriers; on the other hand, it is beneficial to use the diffusion barrier layer to block the diffusion of the material constituting the electrode toward the substrate, effectively reducing the high-density defect state caused by the direct contact between the material constituting the electrode and the substrate. In this way, the cooperation of multiple aspects is conducive to improving the photoelectric conversion efficiency of photovoltaic cells.

[0022] In the description of the embodiments of the present disclosure, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present disclosure, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0023] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present disclosure. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0024] In the description of the embodiments of the present disclosure, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0025] In the description of the embodiments of the present disclosure, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0026] In the description of the embodiments of the present disclosure, the orientations or positional relationships indicated by technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", and "circumferential" are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the embodiments of the present disclosure and simplifying the description. They do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the embodiments of the present disclosure.

[0027] In the description of the embodiments of the present disclosure, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to the specific circumstances.

[0028] In the accompanying drawings corresponding to the embodiments of the present disclosure, the thickness and area of ​​the layers are exaggerated for better understanding and ease of description. When describing a component (such as a layer, film, region or substrate) on another component or on the surface of another component, the component may be "directly" located on the surface of the other component, or a third component may exist between the two components. On the contrary, when describing a component on the surface of another component or when another component is formed or provided on the surface of a component, it means that there is no third component between the two components. In addition, when describing a component as being "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a partial edge of the entire surface.

[0029] In the description of the embodiments of the present disclosure, when a component "includes" another component, unless otherwise specified, other components are not excluded, and other components may be further included. In addition, when a component such as a layer, film, region, or plate is referred to as being "on / located on" another component, it may be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or another component may exist in between. In addition, when a component such as a layer, film, region, or plate is "directly located on" another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it means that no other components are located in between.

[0030] The terms used in the description of the various embodiments described herein are only used to describe specific embodiments and are not intended to be limiting. As used in the description of the various embodiments described and in the appended claims, "the components" are also intended to include plural forms unless the context clearly indicates otherwise. Among them, components include components such as layers, films, regions, or plates.

[0031] The following will describe the various embodiments of the present disclosure in detail with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that in the various embodiments of the present disclosure, many technical details are provided in order to enable the reader to better understand the embodiments of the present disclosure. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the embodiments of the present disclosure can be implemented.

[0032] An embodiment of the present disclosure provides a photovoltaic cell. The solar cell provided by an embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0033] refer to Figure 1 or Figure 2 The photovoltaic cell includes: a substrate 100 and a tunneling layer 101 located on the back side 110 of the substrate 100; a nitrogen-phosphorus co-doped polysilicon layer 102 located on a side of the tunneling layer 101 away from the substrate 100; a diffusion barrier layer 103 located on a side of the nitrogen-phosphorus co-doped polysilicon layer 102 away from the tunneling layer 101; and a phosphorus-doped polysilicon layer 104 located on a side of the diffusion barrier layer 103 away from the nitrogen-phosphorus co-doped polysilicon layer 102.

[0034] in, Figure 1 A schematic diagram of a partial cross-sectional structure of a photovoltaic cell provided in one embodiment of the present disclosure; Figure 2 Another schematic diagram of a partial cross-sectional structure of a photovoltaic cell provided in one embodiment of the present disclosure.

[0035] It is worth emphasizing that the doping layer for passivating the surface defects on the back side 110 of the substrate 100 is divided into two layers arranged in an upper and lower interval, namely, the nitrogen-phosphorus co-doped polysilicon layer 102 and the phosphorus-doped polysilicon layer 104, and the nitrogen-phosphorus co-doped polysilicon layer 102 and the phosphorus-doped polysilicon layer 104 contain different doping elements. Furthermore, a diffusion barrier layer 103 is arranged between the nitrogen-phosphorus co-doped polysilicon layer 102 and the phosphorus-doped polysilicon layer 104.

[0036] Thus, on the one hand, the nitrogen-phosphorus co-doped polysilicon layer 102 closest to the tunneling layer 101 is designed to contain two doping elements, nitrogen and phosphorus. Compared with the polysilicon layer not doped with nitrogen, it is beneficial to increase the optical band gap of the nitrogen-phosphorus co-doped polysilicon layer 102 by introducing nitrogen, so that the nitrogen-phosphorus co-doped polysilicon layer 102 can transmit light in a wider band, while reducing the parasitic absorption of the nitrogen-phosphorus co-doped polysilicon layer 102 to light in the near-infrared band, thereby taking a two-pronged approach to improve the transmittance of the nitrogen-phosphorus co-doped polysilicon layer 102 to light, thereby improving the absorption and utilization rate of light by the substrate 100.

[0037] On the other hand, the nitrogen element doped in the nitrogen-phosphorus co-doped polysilicon layer 102 can be enriched at the interface where the tunneling layer 101 contacts the nitrogen-phosphorus co-doped polysilicon layer 102, and the nitrogen element can capture the hydrogen element, which is beneficial to increase the concentration of the hydrogen element at the interface where the tunneling layer 101 contacts the nitrogen-phosphorus co-doped polysilicon layer 102, so as to improve the passivation effect of the nitrogen-phosphorus co-doped polysilicon layer 102 on the back side 110, such as passivating more defect states on the back side 110, so that the back side 110 has a lower interface state density, effectively reducing the probability of carrier recombination, achieving ultra-low surface recombination current, and increasing the lifetime of minority carriers, thereby improving the implicit open circuit voltage of the photovoltaic cell.

[0038] On the other hand, the phosphorus-doped polysilicon layer 104 is designed to be in contact with the electrode 106 in the photovoltaic cell. Compared with the nitrogen-phosphorus co-doped polysilicon layer 102, the phosphorus-doped polysilicon layer 104 has a lower resistivity. The resistivity of the phosphorus-doped polysilicon layer 104 itself can be reduced by doping with phosphorus, so as to further reduce the contact resistance between the electrode 106 and the phosphorus-doped polysilicon layer 104, thereby improving the collection efficiency of the electrode 106 for carriers.

[0039] On the other hand, providing a diffusion barrier layer 103 between the nitrogen-phosphorus co-doped polysilicon layer 102 and the phosphorus-doped polysilicon layer 104 is beneficial for blocking the diffusion of the material constituting the electrode 106 toward the substrate 100 with the help of the diffusion barrier layer 103, and effectively reducing the high-density defect states caused by the direct contact between the material constituting the electrode 106 and the substrate 100, thereby improving the photoelectric conversion efficiency of the photovoltaic cell.

[0040] In some cases, the implicit open circuit voltage of the photovoltaic cell provided by an embodiment of the present disclosure can reach 760mV or above, and the SRH recombination (Shockley-Read-Hall, indirect recombination) current is less than 0.1fA / cm 2 , the lifetime of minority carriers reaches 20ms or more, which is beneficial to improve the open circuit voltage, fill factor and short circuit current of photovoltaic cells.

[0041] The photovoltaic cell provided in one embodiment of the present disclosure will be described in more detail below with reference to the accompanying drawings.

[0042] In some embodiments, reference Figure 1 or Figure 2 The photovoltaic cell may further include: a passivation layer 108, at least located on the side of the phosphorus-doped polysilicon layer 104 away from the back surface 110. It should be noted that: Figure 1 and Figure 2 In the figure, it is only taken as an example that the passivation layer 108 is disposed on both the front side 130 and the back side 110 of the photovoltaic cell.

[0043] In some cases, passivation layer 108 may include at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride.

[0044] In some examples, the passivation layer 108 may be a stacked structure, and for a multi-layer structure, the materials of different layers may be different from each other, or the materials of some layers may be the same and different from the materials of other layers. Figure 1 and Figure 2 In the embodiment, the passivation layer 108 is a stacked structure of an aluminum oxide layer 118 and a silicon nitride layer 128. In other examples, the passivation layer may also be a single-layer structure.

[0045] In some embodiments, reference Figure 2 The photovoltaic cell may further include: an electrode 106, which is at least located on the back surface 110, and the electrode 106 is embedded in the passivation layer 108 and is in contact with the phosphorus-doped polysilicon layer 104. It should be noted that: Figure 2 It is merely taken as an example that both the front side 130 and the back side 110 of the photovoltaic cell are provided with electrodes 106 .

[0046] In some examples, the material of electrode 106 may include at least one of silver, aluminum, copper, tin, gold, lead, or nickel.

[0047] In some embodiments, reference Figure 1 or Figure 2 The doping concentration of nitrogen in the nitrogen-phosphorus co-doped polysilicon layer 102 may be 1×10 17 atom / cm 3 ~1×10 20 atom / cm 3 .

[0048] It is worth noting that if the doping concentration of nitrogen in the nitrogen-phosphorus co-doped polysilicon layer 102 is less than 1×10 17 atom / cm 3, the nitrogen content in the nitrogen-phosphorus co-doped polysilicon layer 102 is relatively small, which will weaken the ability of the nitrogen-phosphorus co-doped polysilicon layer 102 to capture hydrogen, and the effect of increasing the concentration of hydrogen at the interface between the tunneling layer 101 and the nitrogen-phosphorus co-doped polysilicon layer 102 is limited. In addition, the nitrogen content in the nitrogen-phosphorus co-doped polysilicon layer 102 is relatively small, which makes it easier for the nitrogen-phosphorus co-doped polysilicon layer 102 to be doped with more phosphorus. If the phosphorus content in the nitrogen-phosphorus co-doped polysilicon layer 102 is too high, the risk of phosphorus diffusion into the substrate 100 will be increased. If the doping concentration of nitrogen in the nitrogen-phosphorus co-doped polysilicon layer 102 is greater than 1×10 20 atom / cm 3 , the nitrogen content in the nitrogen-phosphorus co-doped polysilicon layer 102 is relatively large, which is not conducive to increasing the phosphorus content in the nitrogen-phosphorus co-doped polysilicon layer 102, and thus is not conducive to regulating the nitrogen-phosphorus co-doped polysilicon layer 102 to have a lower resistivity. On this basis, the doping concentration of nitrogen in the nitrogen-phosphorus co-doped polysilicon layer 102 is designed to be 1×10 17 atom / cm 3 ~1×10 20 atom / cm 3 , which is beneficial to simultaneously control the nitrogen content and the phosphorus content in the nitrogen-phosphorus co-doped polysilicon layer 102 to be moderate, thereby ensuring that the nitrogen-phosphorus co-doped polysilicon layer 102 has a good ability to capture hydrogen elements, so as to effectively improve the concentration of hydrogen elements at the interface where the tunneling layer 101 and the nitrogen-phosphorus co-doped polysilicon layer 102 are in contact, while ensuring that the phosphorus content in the nitrogen-phosphorus co-doped polysilicon layer 102 is moderate, so as to reduce the risk of phosphorus elements diffusing into the substrate 100, and make the nitrogen-phosphorus co-doped polysilicon layer 102 have a lower resistivity, thereby ensuring that the photovoltaic cell has a higher open circuit voltage and short circuit current.

[0049] In some examples, the doping concentration of nitrogen in the nitrogen-phosphorus co-doped polysilicon layer 102 may be 1×10 17 atom / cm 3 ~1×10 20 atom / cm 3 , for example, it can be 2×10 17 atom / cm 3 , 5×10 17 atom / cm 3 , 8×10 17 atom / cm 3 , 1×10 18 atom / cm 3 , 3×10 18 atom / cm 3 , 5×10 18 atom / cm 3 ,7×10 18 atom / cm3 , 1×10 19 atom / cm 3 , 2×10 19 atom / cm 3 , 4×10 19 atom / cm 3 , 5×10 19 atom / cm 3 , 6×10 19 atom / cm 3 or 8×10 19 atom / cm 3 wait.

[0050] In some embodiments, reference Figure 1 or Figure 2 , along the direction X from the tunneling layer 101 to the substrate 100, the doping concentration of phosphorus in the nitrogen-phosphorus co-doped polysilicon layer 102 gradually decreases, and the doping concentration of phosphorus in the nitrogen-phosphorus co-doped polysilicon layer 102 can be 0.1×10 17 atom / cm 3 ~5×10 21 atom / cm 3 .

[0051] It should be noted that the doping concentration of phosphorus in the nitrogen-phosphorus co-doped polysilicon layer 102 refers to the average doping concentration of phosphorus in the entire nitrogen-phosphorus co-doped polysilicon layer 102. In other words, the average doping concentration of phosphorus in the entire nitrogen-phosphorus co-doped polysilicon layer 102 can be 0.1×10 17 atom / cm 3 ~5×10 21 atom / cm 3 .

[0052] It is worth noting that, on the one hand, along the direction X from the tunneling layer 101 to the substrate 100, the doping concentration of phosphorus in the nitrogen-phosphorus co-doped polysilicon layer 102 gradually decreases. In other words, the concentration of phosphorus at the interface where the tunneling layer 101 contacts the nitrogen-phosphorus co-doped polysilicon layer 102 is less than the concentration of phosphorus at the interface where the nitrogen-phosphorus co-doped polysilicon layer 102 contacts the diffusion barrier layer 103. In this way, it is beneficial to further reduce the concentration of phosphorus at the interface where the tunneling layer 101 contacts the nitrogen-phosphorus co-doped polysilicon layer 102, so as to further reduce the risk of phosphorus diffusion into the substrate 100. At the same time, it is ensured that the average doping concentration of phosphorus in the entire nitrogen-phosphorus co-doped polysilicon layer 102 is high, so as to improve the conductivity of the entire nitrogen-phosphorus co-doped polysilicon layer 102, thereby reducing the transmission resistance of carriers in the nitrogen-phosphorus co-doped polysilicon layer 102, so as to improve the collection efficiency of carriers by the photovoltaic cell.

[0053] On the other hand, if the doping concentration of phosphorus in the nitrogen-phosphorus co-doped polysilicon layer 102 is less than 0.1×10 17 atom / cm 3 , the phosphorus content in the nitrogen-phosphorus co-doped polysilicon layer 102 is relatively small, which is not conducive to regulating the nitrogen-phosphorus co-doped polysilicon layer 102 to have a lower resistivity; if the doping concentration of phosphorus in the nitrogen-phosphorus co-doped polysilicon layer 102 is greater than 5×10 21 atom / cm 3 , the phosphorus content in the nitrogen-phosphorus co-doped polysilicon layer 102 is relatively large, which is not conducive to increasing the nitrogen content in the nitrogen-phosphorus co-doped polysilicon layer 102, and has limited effect on increasing the concentration of hydrogen at the interface between the tunneling layer 101 and the nitrogen-phosphorus co-doped polysilicon layer 102, and is not conducive to reducing the risk of phosphorus diffusion into the substrate 100. On this basis, the doping concentration of phosphorus in the nitrogen-phosphorus co-doped polysilicon layer 102 is designed to be 0.1×10 17 atom / cm 3 ~5×10 21 atom / cm 3 , which is beneficial to simultaneously control the nitrogen content and the phosphorus content in the nitrogen-phosphorus co-doped polysilicon layer 102 to be moderate, thereby ensuring that the nitrogen-phosphorus co-doped polysilicon layer 102 has a good ability to capture hydrogen elements, so as to effectively increase the concentration of hydrogen elements at the interface where the tunneling layer 101 and the nitrogen-phosphorus co-doped polysilicon layer 102 are in contact, while ensuring that the phosphorus content in the nitrogen-phosphorus co-doped polysilicon layer 102 is moderate, so as to reduce the risk of phosphorus elements diffusing into the substrate 100, thereby ensuring that the photovoltaic cell has a higher open circuit voltage and short circuit current.

[0054] In some examples, the doping concentration of phosphorus in the nitrogen-phosphorus co-doped polysilicon layer 102 may be 0.5×10 17 atom / cm 3 , 0.8×10 17 atom / cm 3 , 1×10 17 atom / cm 3 , 2×10 17 atom / cm 3 , 5×10 17 atom / cm 3 , 8×10 17 atom / cm 3 , 1×10 18 atom / cm 3 , 3×10 18 atom / cm 3 , 5×10 18 atom / cm 3 ,7×10 18 atom / cm 3, 1×10 19 atom / cm 3 , 2×10 19 atom / cm 3 , 4×10 19 atom / cm 3 , 5×10 19 atom / cm 3 , 6×10 19 atom / cm 3 , 8×10 19 atom / cm 3 , 1×10 20 atom / cm 3 or 3×10 20 atom / cm 3 wait.

[0055] In some cases, compared with the gradually decreasing doping concentration of phosphorus in the nitrogen-phosphorus co-doped polysilicon layer 102 along the direction X, the nitrogen in the nitrogen-phosphorus co-doped polysilicon layer 102 can be considered to be uniformly distributed. In other words, the doping concentration of nitrogen in the nitrogen-phosphorus co-doped polysilicon layer 102 along the direction X does not change significantly, and the doping concentration of nitrogen in various regions of the nitrogen-phosphorus co-doped polysilicon layer 102 is almost the same.

[0056] In some embodiments, reference Figure 1 or Figure 2 , the nitrogen-phosphorus co-doped polysilicon layer 102 may also be doped with hydrogen. It is worth noting that in the step of preparing the nitrogen-phosphorus co-doped polysilicon layer 102, ammonia gas may be used as a doping source for doping nitrogen into the polysilicon layer, so that the nitrogen-phosphorus co-doped polysilicon layer 102 is also doped with hydrogen, so that the nitrogen-phosphorus co-doped polysilicon layer 102 can be used to capture hydrogen, thereby further increasing the concentration of hydrogen at the interface where the tunneling layer 101 and the nitrogen-phosphorus co-doped polysilicon layer 102 are in contact.

[0057] In some embodiments, reference Figure 1 or Figure 2, the average doping concentration of phosphorus in the nitrogen-phosphorus co-doped polysilicon layer 102 is a first doping concentration, the average doping concentration of phosphorus in the phosphorus-doped polysilicon layer 104 is a second doping concentration, and the first doping concentration is less than the second doping concentration. In this way, it is beneficial to make the resistivity of the phosphorus-doped polysilicon layer 104 lower than the resistivity of the nitrogen-phosphorus co-doped polysilicon layer 102, so as to reduce the contact resistance between the electrode 106 and the phosphorus-doped polysilicon layer 104, and improve the collection efficiency of the electrode 106 for carriers; and, compared with the phosphorus-doped polysilicon layer 104, the average doping concentration of phosphorus in the nitrogen-phosphorus co-doped polysilicon layer 102 is controlled to be lower, which is beneficial to reduce the risk of phosphorus diffusion into the substrate 100, so as to reduce the recombination center in the substrate 100, thereby reducing the probability of carrier recombination in the substrate 100, and thus improving the carrier density transmitted to the electrode 106.

[0058] In addition, with the help of the diffusion barrier layer 103 located between the nitrogen-phosphorus co-doped polysilicon layer 102 and the phosphorus-doped polysilicon layer 104, the phosphorus element in the phosphorus-doped polysilicon layer 104 with a higher phosphorus content can be blocked from diffusing into the nitrogen-phosphorus co-doped polysilicon layer 102 with a lower phosphorus content, so as to take into account the low contact resistance between the phosphorus-doped polysilicon layer 104 and the electrode 106 and the low probability of the phosphorus element diffusing into the substrate 100.

[0059] In some cases, the ratio of the second doping concentration to the first doping concentration may be 10-1000, in other words, the average doping concentration of phosphorus in the phosphorus-doped polysilicon layer 104 is much higher than the doping concentration of phosphorus in the nitrogen-phosphorus co-doped polysilicon layer 102. In some examples, the ratio of the second doping concentration to the first doping concentration may be 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900 or 950, etc.

[0060] In some examples, the doping concentration of phosphorus in the phosphorus-doped polysilicon layer 104 may be 1×10 20 atom / cm 3 ~5×10 21 atom / cm 3 , for example, it can be 2×10 20 atom / cm 3 , 3×10 20 atom / cm 3 , 4×10 20 atom / cm 3 , 5×10 20 atom / cm 3 , 6×10 20 atom / cm 3 ,7×10 20 atom / cm3 , 8×10 20 atom / cm 3 ,9×10 20 atom / cm 3 , 1×10 21 atom / cm 3 , 2×10 21 atom / cm 3 , 3×10 21 atom / cm 3 or 4×10 21 atom / cm 3 etc. In some cases, the diffusion barrier layer 103 may also be doped with phosphorus. It is worth noting that in the steps of preparing the nitrogen-phosphorus co-doped polysilicon layer 102 and the phosphorus-doped polysilicon layer 104, the phosphorus-doping process can be carried out simultaneously, so in the environment of the phosphorus-doping process structure, part of the phosphorus element will be diffused into the diffusion barrier layer 103 and the initial film layer used to form the nitrogen-phosphorus co-doped polysilicon layer 102 in sequence, and after the doping process is completed, part of the phosphorus element will remain in the diffusion barrier layer 103. It is worth emphasizing that in the normal working environment of the photovoltaic cell, a very small amount of phosphorus element will diffuse from the phosphorus-doped polysilicon layer 104 into the diffusion barrier layer 103.

[0061] In some embodiments, reference Figure 1 or Figure 2 The interface where the nitrogen-phosphorus co-doped polysilicon layer 102 contacts the tunneling layer 101 is the reference interface, and the nitrogen content at the reference interface is greater than or equal to 1×10 20 atom / cm 3 , which is beneficial to ensure the enrichment of nitrogen at the reference interface, thereby helping to increase the concentration of hydrogen at the reference interface.

[0062] In some embodiments, the content of phosphorus at the reference interface may be 0.5×10 17 atom / cm 3 ~1×10 21 cm -3 atom / cm 3 , for example, it can be 0.6×10 17 atom / cm 3 , 0.8×10 17 atom / cm 3 , 1×10 17 atom / cm 3 , 2×10 17 atom / cm 3 , 5×10 17 atom / cm 3 , 8×10 17atom / cm 3 , 1×10 18 atom / cm 3 , 3×10 18 atom / cm 3 , 5×10 18 atom / cm 3 ,7×10 18 atom / cm 3 , 1×10 19 atom / cm 3 , 2×10 19 atom / cm 3 , 4×10 19 atom / cm 3 , 5×10 19 atom / cm 3 , 6×10 19 atom / cm 3 , 8×10 19 atom / cm 3 , 1×10 20 atom / cm 3 , 3×10 20 atom / cm 3 , 5×10 20 atom / cm 3 , 6×10 20 atom / cm 3 or 8×10 20 atom / cm 3 wait.

[0063] In some embodiments, reference Figure 1 or Figure 2 The material of the diffusion barrier layer 103 may include at least one of silicon oxynitride, silicon nitride or silicon oxide.

[0064] In some embodiments, in the direction X along the tunneling layer 101 pointing to the substrate 100, the thickness of the diffusion barrier layer 103 can be 0.5nm~10nm, for example, can be 0.8nm, 1nm, 1.5nm, 2nm, 2.5nm, 3nm, 3.5nm, 4nm, 4.5nm, 5nm, 5.5nm, 6nm, 6.5nm, 7nm, 7.5nm, 8nm, 8.5nm, 9nm or 9.5nm, etc.

[0065] In some embodiments, reference Figure 1 or Figure 2, along the direction X from the tunneling layer 101 to the substrate 100, the thickness of the nitrogen-phosphorus co-doped polysilicon layer 102 is less than the thickness of the phosphorus-doped polysilicon layer 104. Thus, the thickness of the phosphorus-doped polysilicon layer 104 is designed to be relatively large, which is beneficial to reducing the resistivity of the phosphorus-doped polysilicon layer 104 itself, so as to ensure the thickness of the phosphorus-doped polysilicon layer 104 and the good ohmic contact of the electrode 106; the thickness of the nitrogen-phosphorus co-doped polysilicon layer 102 is designed to be relatively small, which is beneficial to improving the passivation effect of the passivation structure composed of the tunneling layer 101 and the nitrogen-phosphorus co-doped polysilicon layer 102 on the substrate 100, for example, improving the electric field strength formed by the nitrogen-phosphorus co-doped polysilicon layer 102 to improve the field passivation effect on the substrate 100.

[0066] In some cases, the phosphorus content in the nitrogen-phosphorus co-doped polysilicon layer 102 is less than the phosphorus content in the phosphorus-doped polysilicon layer 104, and most carriers in the substrate 100 need to pass through the nitrogen-phosphorus co-doped polysilicon layer 102, the diffusion barrier layer 103, and the phosphorus-doped polysilicon layer 104 in sequence, and finally be collected by the electrode 106. On this basis, the thickness of the nitrogen-phosphorus co-doped polysilicon layer 102 is designed to be less than the thickness of the phosphorus-doped polysilicon layer 104, so that the phosphorus-doped polysilicon layer 104 accounts for a larger proportion of the polysilicon as a whole composed of the nitrogen-phosphorus co-doped polysilicon layer 102 and the phosphorus-doped polysilicon layer 104, which is conducive to increasing the phosphorus content of the polysilicon as a whole, thereby reducing the resistivity of the polysilicon as a whole, so as to reduce the transmission resistance in the process of carriers being transmitted from the substrate 100 to the electrode 106, thereby improving the collection efficiency of the electrode 106 for carriers.

[0067] In some examples, in the direction X along the tunneling layer 101 pointing to the substrate 100, the thickness of the nitrogen-phosphorus co-doped polysilicon layer 102 can be 20nm~70nm, for example, can be 22nm, 24nm, 25nm, 26nm, 30nm, 32nm, 35nm, 36nm, 40nm, 43nm, 45nm, 48nm, 50nm, 52nm, 55nm, 56nm, 60nm, 63nm, 65nm or 68nm, etc.

[0068] In some examples, in the direction X along the tunneling layer 101 pointing to the substrate 100, the thickness of the phosphorus-doped polysilicon layer 104 can be 70nm~130nm, for example, can be 72nm, 74nm, 75nm, 76nm, 80nm, 82nm, 85nm, 86nm, 90nm, 93nm, 95nm, 98nm, 100nm, 102nm, 105nm, 106nm, 110nm, 113nm, 115nm, 118nm, 120nm, 124nm, 125nm, 126nm or 128nm, etc.

[0069] In some embodiments, reference Figure 1 or Figure 2, the material of the tunneling layer 101 may be silicon oxide.

[0070] In some embodiments, reference Figure 1 or Figure 2 Along the direction X, the thickness of the tunneling layer 101 may be 1 nm to 2 nm, for example, 1.1 nm, 1.2 nm, 1.3 nm, 1.4 nm, 1.5 nm, 1.6 nm, 1.7 nm, 1.8 nm or 1.9 nm.

[0071] In summary, on the one hand, the nitrogen-phosphorus co-doped polysilicon layer 102 closest to the tunneling layer 101 is designed to contain two doping elements, nitrogen and phosphorus. Compared with the polysilicon layer not doped with nitrogen, it is beneficial to increase the optical band gap of the nitrogen-phosphorus co-doped polysilicon layer 102 by introducing nitrogen, and reduce the parasitic absorption of the nitrogen-phosphorus co-doped polysilicon layer 102 to light in the near-infrared band; on the other hand, the nitrogen doped in the nitrogen-phosphorus co-doped polysilicon layer 102 can be enriched at the interface where the tunneling layer 101 and the nitrogen-phosphorus co-doped polysilicon layer 102 contact, and the nitrogen element can capture hydrogen, which is beneficial to improve the nitrogen-phosphorus co-doped polysilicon layer 101. 2 has a passivation effect on the back surface 110; on the other hand, the phosphorus-doped polysilicon layer 104 is designed to be in contact with the electrode 106 in the photovoltaic cell. Compared with the nitrogen-phosphorus co-doped polysilicon layer 102, the phosphorus-doped polysilicon layer 104 has a lower resistivity, which can further reduce the contact resistance between the electrode 106 and the phosphorus-doped polysilicon layer 104, so as to improve the collection efficiency of the electrode 106 for carriers; on the other hand, it is beneficial to use the diffusion barrier layer 103 to block the diffusion of the material constituting the electrode 106 toward the substrate 100, and effectively reduce the high-density defect state caused by the direct contact between the material constituting the electrode 106 and the substrate 100. In this way, the cooperation of multiple aspects is conducive to improving the photoelectric conversion efficiency of the photovoltaic cell.

[0072] Another embodiment of the present disclosure further provides a method for manufacturing a photovoltaic cell, which is used to prepare the photovoltaic cell provided in the above embodiment. The method for manufacturing a photovoltaic cell provided in another embodiment of the present disclosure will be described in detail below in conjunction with the accompanying drawings. Figures 3 to 8 This is a schematic diagram of the partial cross-sectional structure corresponding to each step in the method for manufacturing a photovoltaic cell provided in another embodiment of the present disclosure. It should be noted that the parts that are the same as or corresponding to the aforementioned embodiments are not repeated here.

[0073] in, Figure 3 A schematic diagram of a partial cross-sectional structure of an initial substrate provided in a method for manufacturing a photovoltaic cell provided in another embodiment of the present disclosure; Figure 4 A schematic diagram of a partial cross-sectional structure of a substrate provided in a method for manufacturing a photovoltaic cell provided in another embodiment of the present disclosure; Figure 5A schematic diagram of a partial cross-sectional structure in which a tunneling layer and a first silicon material layer are formed on a substrate in a method for manufacturing a photovoltaic cell provided by another embodiment of the present disclosure; Figure 6 For Figure 5 A schematic diagram of a local cross-sectional structure formed after nitrogen doping treatment based on the structure shown; Figure 7 For Figure 6 A schematic diagram of a partial cross-sectional structure after a diffusion barrier film and a second silicon material layer are formed on the basis of the structure shown; Figure 8 For Figure 7 A schematic diagram of a local cross-sectional structure formed after phosphorus doping treatment is performed on the basis of the structure shown.

[0074] Combined with reference Figures 1 to 8 , the manufacturing method of the photovoltaic cell comprises at least the following steps: refer to Figures 3 to 5 , providing a substrate 100 , and forming a tunneling layer 101 on a back side 110 of the substrate 100 .

[0075] Continue to refer Figure 5 , a first silicon material layer 112 is formed on a side of the tunneling layer 101 away from the substrate 100 .

[0076] Combined with reference Figure 5 and Figure 6 , the first silicon material layer 112 is nitrogen-doped to transform the first silicon material layer 112 into a nitrogen-doped layer 122 .

[0077] Combined with reference Figure 6 and Figure 7 A diffusion barrier film 113 is formed on a side of the nitrogen-doped layer 122 away from the tunneling layer 101 ; and a second silicon material layer 114 is formed on a side of the diffusion barrier film 113 away from the nitrogen-doped layer 122 .

[0078] Combined with reference Figure 7 and Figure 8 The nitrogen-doped layer 122, the diffusion barrier film 113 and the second silicon material layer 114 are subjected to phosphorus doping treatment as a whole to convert the nitrogen-doped layer 122 into a nitrogen-phosphorus co-doped polysilicon layer 102, the diffusion barrier film 113 into a diffusion barrier layer 103, and the second silicon material layer 114 into a phosphorus-doped polysilicon layer 104.

[0079] It is worth noting that before the phosphorus doping treatment is performed, the first silicon material layer 112 is nitrogen doped to introduce nitrogen into the first silicon material layer 112. Subsequently, the nitrogen element is used to allow light in a wider band to penetrate into the substrate 100, while reducing the parasitic absorption of light in the near-infrared band by the first silicon material layer 112 after nitrogen doping, thereby improving the absorption utilization rate of light by the substrate 100; and, by capturing hydrogen with the help of nitrogen, the concentration of hydrogen at the interface where the tunneling layer 101 and the nitrogen-phosphorus co-doped polysilicon layer 102 are increased, so as to passivate more defect states on the back side 110, so that the back side 110 has a lower interface state density, effectively reducing the probability of carrier recombination, achieving ultra-low surface recombination current, and increasing the lifetime of minority carriers, thereby improving the implicit open circuit voltage of the photovoltaic cell finally formed.

[0080] In some cases, the first silicon material layer 112 is subsequently used to form the nitrogen-phosphorus co-doped polysilicon layer 102, the diffusion barrier film 113 is subsequently used to form the diffusion barrier layer 103, and the second silicon material layer 114 is subsequently used to form the phosphorus-doped polysilicon layer 104. Before the phosphorus doping process is performed, the diffusion barrier film 113 is first prepared between the first silicon material layer 112 and the second silicon material layer 114, so that during the phosphorus doping process, the diffusion barrier film 113 can have a certain blocking effect on the phosphorus element, thereby reducing the speed of the phosphorus element diffusing into the first silicon material layer 112. In other words, because the diffusion barrier film 113 has a certain blocking effect, the amount of phosphorus element diffused into the first silicon material layer 112 is less than the amount of phosphorus element diffused into the second silicon material layer 114 in the same time. This helps to make the doping concentration of phosphorus in the nitrogen-phosphorus co-doped polysilicon layer 102 lower than the doping concentration in the phosphorus-doped polysilicon layer 104, thereby reducing the contact resistance between the electrode 106 and the phosphorus-doped polysilicon layer 104 and reducing the risk of phosphorus diffusing into the substrate 100.

[0081] In some cases, in the step of forming the diffusion barrier film 113, the thickness of the formed diffusion barrier film 113 can also be controlled to regulate the strength of the diffusion barrier film 113's barrier effect on the phosphorus element, so as to regulate the phosphorus content in the finally formed nitrogen-phosphorus co-doped polysilicon layer 102.

[0082] A method for manufacturing a photovoltaic cell provided by another embodiment of the present disclosure will be described in more detail below with reference to the accompanying drawings.

[0083] In some embodiments, the step of providing the substrate 100 may include: referring to Figure 3 , providing a substrate (not shown in the figure), and sequentially performing a cleaning process, a texturing process and a pre-boron process on the substrate to form an initial substrate 120 with a texturing surface on both sides, and a boron diffusion layer 107 is formed on the front side of the initial substrate 120 through the pre-boron process; Figure 3 and Figure 4 The back side of the initial substrate 120 is polished to form a substrate 100 having a velvet surface on the front side 130 and a polished surface on the back side 110 .

[0084] In some examples, the material of the substrate 100 may be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon or germanium. Among them, the elemental semiconductor material may be single crystalline, polycrystalline, amorphous or microcrystalline (a state having both single crystalline and amorphous states is called microcrystalline), for example, silicon may be at least one of single crystalline silicon, polycrystalline silicon, amorphous silicon or microcrystalline silicon. In other embodiments, the material of the substrate 100 may also be a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, silicon germanium, silicon carbide, gallium arsenide, indium gallium, perovskite, cadmium telluride, copper indium selenide and other materials.

[0085] In some examples, the substrate 100 may be an N-type semiconductor substrate. The N-type semiconductor substrate is doped with an N-type doping element, which may be at least one of Group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As).

[0086] In some embodiments, in conjunction with reference Figure 5 and Figure 6 The step of performing nitrogen doping treatment on the first silicon material layer 112 may include: treating the first silicon material layer 112 with plasma ammonia gas, so that nitrogen and hydrogen elements are doped into the first silicon material layer 112. In this way, in the step of preparing the nitrogen-doped layer 122, the nitrogen-doped layer 122 is also doped with hydrogen elements, so as to utilize the characteristic of nitrogen elements capturing hydrogen elements, thereby further increasing the concentration of hydrogen elements at the interface where the tunneling layer 101 and the nitrogen-doped layer 122 contact, so as to improve the passivation effect on the substrate 100.

[0087] In some embodiments, in conjunction with reference Figure 7 and Figure 8 In the step of performing phosphorus doping treatment, based on the barrier effect of the diffusion barrier film 113 on phosphorus, the doping concentration of phosphorus in the nitrogen-doped layer 122 closer to the substrate 100 is lower.

[0088] It is worth noting that, based on the blocking effect of the diffusion barrier film 113 on the phosphorus element, the deeper the diffusion into the nitrogen-doped layer 122, the less phosphorus element can diffuse to a deeper depth, thereby making the doping concentration of phosphorus element in the nitrogen-doped layer 122 closer to the substrate 100 lower, so that the doping concentration of phosphorus element in the finally formed nitrogen-phosphorus co-doped polysilicon layer 102 along the direction X gradually decreases.

[0089] In some cases, in the step of forming the diffusion barrier film 113, the thickness of the formed diffusion barrier film 113 can also be controlled to regulate the strength of the barrier effect of the diffusion barrier film 113 on the phosphorus element, so as to achieve a gradual decrease in the doping concentration of the phosphorus element in the nitrogen-phosphorus co-doped polysilicon layer 102 along the direction X.

[0090] In some embodiments, in conjunction with reference Figure 5 and Figure 7 , the first silicon material layer 112 and the second silicon material layer 114 can both be amorphous silicon, then the first silicon material layer 112 doped with nitrogen, that is, the nitrogen-doped layer 122 can also be amorphous silicon; the step of performing phosphorus doping treatment may include: forming a phosphorus doping source layer on the side of the second silicon material layer 114 away from the diffusion barrier film 113; performing annealing treatment to diffuse the phosphorus element in the phosphorus doping source layer into the second silicon material layer 114, the diffusion barrier film 113 and the nitrogen-doped layer 122 in sequence, and converting the first silicon material layer 112 and the second silicon material layer 114 into polycrystalline silicon. It is worth noting that in the step of performing phosphorus doping treatment, converting the first silicon material layer 112 into polycrystalline silicon refers to converting the first silicon material layer 112 doped with nitrogen, that is, the nitrogen-doped layer 122 into polycrystalline silicon.

[0091] In some cases, the temperature of the annealing treatment can be 800°C-1100°C, for example, it can be 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C, 890°C, 900°C, 910°C, 920°C, 930°C, 940°C, 950°C, 960°C, 970°C, 980°C, 990°C or 1000°C, etc.

[0092] In other embodiments, both the first silicon material layer and the second silicon material layer can be polycrystalline silicon that is not doped with phosphorus. During the phosphorus doping treatment, it is only necessary to control the phosphorus element in the phosphorus doping source layer to diffuse into the second silicon material layer, the diffusion barrier film and the nitrogen-doped layer in sequence, without the need to implement crystallization of amorphous silicon.

[0093] In some embodiments, in conjunction with reference Figure 8 and Figure 1 The method for manufacturing a photovoltaic cell may further include: forming a passivation layer 108, wherein the passivation layer 108 is at least located on a side of the phosphorus-doped polysilicon layer 104 away from the back surface 110. It should be noted that: Figure 1 and Figure 2 The boron diffusion layer between the passivation layer 108 and the substrate 100 is not shown in the figures.

[0094] In some embodiments, in conjunction with reference Figure 1 and Figure 2The method for manufacturing a photovoltaic cell may further include: forming an electrode 106 , wherein the electrode 106 is at least located on the back side 110 , and the electrode 106 is embedded in the passivation layer 108 and is in contact with the phosphorus-doped polysilicon layer 104 .

[0095] In some examples, the step of forming the electrode 106 may include: forming the electrode 106 using a screen printing process or an electroplating process.

[0096] In summary, in the preparation method provided by another embodiment of the present disclosure, before the phosphorus doping treatment, the first silicon material layer 112 is subjected to nitrogen doping treatment to introduce nitrogen element only into the first silicon material layer 112; and the nitrogen doping layer 122, the diffusion barrier film 113 and the second silicon material layer 114 are subjected to phosphorus doping treatment as a whole to simultaneously form the nitrogen-phosphorus co-doped polysilicon layer 102, the diffusion barrier layer 103 and the phosphorus-doped polysilicon layer 104. This is beneficial to simplify the manufacturing process of the photovoltaic cell while improving the absorption utilization rate of the substrate 100 for light and the passivation effect on the substrate 100 with the help of nitrogen element.

[0097] Another embodiment of the present disclosure further provides a photovoltaic module, which is used to convert received light energy into electrical energy. The photovoltaic module provided by another embodiment of the present disclosure will be described in detail below in conjunction with the accompanying drawings. It should be noted that the parts that are the same or corresponding to the above embodiments are not repeated here.

[0098] Combined with reference Figure 1 , Figure 2 , Fig. 9 and Fig.10 , the photovoltaic module includes: a cell string, which is formed by connecting a plurality of photovoltaic cells 40 as provided in the above embodiments, or by connecting a plurality of photovoltaic cells 40 formed by the manufacturing method provided in the above embodiments; a packaging film 41, which is used to cover the surface of the cell string; a cover plate 42, which is used to cover the surface of the packaging film 41 away from the cell string. The photovoltaic cells 40 are electrically connected in the form of a whole piece or multiple pieces to form a plurality of cell strings, and the plurality of cell strings are electrically connected in series and / or in parallel. In other words, the photovoltaic cell 40 can be a whole cell or a sliced ​​cell, and a sliced ​​cell refers to a cell formed by a complete whole cell through a cutting process.

[0099] in, Fig. 9 A schematic diagram of a partial three-dimensional structure of a photovoltaic assembly provided by another embodiment of the present disclosure; Fig.10 for Fig. 9 A schematic diagram of a cross-sectional structure along the cross-sectional direction MM1.

[0100] In some embodiments, the photovoltaic cell 40 includes, but is not limited to, one or any combination of cells with a passivation structure such as PERC cells (Passivated Emitter Rear Cell), IBC cells (Interdigitated Back Contact), TOPCon cells (Tunnel Oxide Passivated Contact), HIT / HJT cells (Heterojunction Technology heterojunction cells), solar thin-film cells, and stacked cells. Among them, solar thin-film cells include, but are not limited to, perovskite solar thin-film cells, copper indium selenide solar thin-film cells, gallium arsenide solar thin-film cells, and cadmium sulfide solar thin-film cells. Stacked cells include, but are not limited to, perovskite cells superimposed on crystalline silicon cells, perovskite cells superimposed on perovskite cells, and perovskite cells superimposed on thin-film cells. Figures 1 to 10 Only the photovoltaic cell is taken as an example of a TOPCon cell.

[0101] In some embodiments, reference Fig. 9 and Fig.10 , multiple battery strings can be electrically connected through the conductive tape 402. Fig. 9 Only one positional relationship between photovoltaic cells is illustrated, that is, the arrangement direction of the electrodes with the same polarity of the cells is the same, or the electrodes with positive polarity of each cell are arranged toward the same side, so that the conductive tape connects different sides of two adjacent cells. In some embodiments, the cells can also be arranged in the order of electrodes with different polarities facing the same side, that is, the electrodes of multiple adjacent cells are arranged in the order of the first polarity, the second polarity, and the first polarity, and the conductive tape connects two adjacent cells on the same side.

[0102] In some embodiments, no intervals are set between the battery cells, that is, the battery cells overlap each other.

[0103] In some embodiments, the encapsulation film 41 includes a first encapsulation layer and a second encapsulation layer, the first encapsulation layer covers one of the front or back sides of the photovoltaic cell 40, and the second encapsulation layer covers the other of the front or back sides of the photovoltaic cell 40. Specifically, at least one of the first encapsulation layer or the second encapsulation layer can be an organic encapsulation film such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate copolymer (EVA) film, polyethylene octene co-elastomer (POE) film or polyethylene terephthalate (PET) film, or at least one of the first encapsulation layer or the second encapsulation layer can also be an EP film, EPE film or PVP film. Among them, EP film refers to a co-extruded film composed of stacked EVA film and POE film, EPE film refers to a co-extruded film formed by stacking EVA film + POE film + EVA film in sequence, and PVP film refers to a co-extruded film formed by stacking POE film + EVA film + POE film. The co-extruded film can be prepared by sequentially extruding one or more raw materials onto another already manufactured film during the film processing, or by bonding different types of already manufactured films together.

[0104] In some cases, there is a boundary between the first encapsulation layer and the second encapsulation layer before lamination. After the lamination process, the photovoltaic module is formed and there is no longer the concept of the first encapsulation layer and the second encapsulation layer, that is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film 41.

[0105] In some embodiments, the cover plate 42 may be a glass cover plate, a plastic cover plate or the like with a light-transmitting function. Specifically, the surface of the cover plate 42 facing the encapsulation film 41 may be a concave-convex surface or a velvet surface including a plurality of convex structures, thereby increasing the utilization rate of the incident light. The cover plate 42 includes a first cover plate and a second cover plate, the first cover plate is opposite to the first encapsulation layer, and the second cover plate is opposite to the second encapsulation layer.

[0106] In some embodiments, the photovoltaic cell 40 may be a cell with a main grid or a cell without a main grid. It should be noted that the electrode 106 described in the above embodiments at least includes the subgrid in the photovoltaic cell 40 .

[0107] In some cases, when the photovoltaic cell 40 is a main grid cell, the surface of the photovoltaic cell 40 has a plurality of main grids arranged at intervals along the second direction Y and a plurality of sub-grids arranged at intervals along the third direction Z, and the main grid includes a main grid connection line and a pad located on the main grid connection line. In the process of constructing a battery string using the photovoltaic cell 40, the conductive tape 402 is electrically connected to at least one main grid on each of the two adjacent photovoltaic cells 40. The conductive tape 402 can be electrically connected to the main grid by welding, or the conductive tape 402 can be fixed on the main grid by glue points in advance, and the conductive tape 402 can be electrically connected to the main grid by the fusion of the glue points and the deformation of the conductive tape 402 during the lamination process.

[0108] In other cases, when the photovoltaic cell 40 is a main grid-free cell, the surface of the photovoltaic cell 40 has a plurality of sub-grids arranged at intervals along the third direction. In the process of constructing a battery string using the photovoltaic cell 40, the conductive tape 402 is electrically connected to the plurality of sub-grids on each of the two adjacent photovoltaic cells 40. The conductive tape 402 can be fixed at a specific position above the photovoltaic cell 40 by glue dots, and then the electrical connection between the conductive tape 402 and the sub-grids is achieved by utilizing the fusion of the glue dots and the deformation of the conductive tape 402 during the lamination process.

[0109] Those skilled in the art can understand that the above-mentioned embodiments are specific examples for implementing the present disclosure, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of the embodiments of the present disclosure. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of the present disclosure, so the protection scope of the embodiments of the present disclosure shall be based on the scope defined in the claims.

Claims

1. A photovoltaic cell, characterized in that: include: A substrate and a tunneling layer located on the back side of the substrate; A nitrogen and phosphorus co-doped polysilicon layer, located on a side of the tunneling layer away from the substrate; A diffusion barrier layer, located on a side of the nitrogen-phosphorus co-doped polysilicon layer away from the tunneling layer; The phosphorus-doped polysilicon layer is located on a side of the diffusion barrier layer away from the nitrogen-phosphorus co-doped polysilicon layer.

2. The photovoltaic cell according to claim 1, characterized in that: The doping concentration of nitrogen in the nitrogen-phosphorus co-doped polysilicon layer is 1×10 17 atom / cm 3 ~1×10 20 atom / cm 3 .

3. The photovoltaic cell according to claim 1, characterized in that: Along the direction from the tunnel layer to the substrate, the doping concentration of phosphorus in the nitrogen-phosphorus co-doped polysilicon layer gradually decreases, and the doping concentration of phosphorus in the nitrogen-phosphorus co-doped polysilicon layer is 0.1×10 17 atom / cm 3 ~5×10 21 atom / cm 3 .

4. The photovoltaic cell according to claim 1, characterized in that: The material of the diffusion barrier layer includes at least one of silicon oxynitride, silicon nitride or silicon oxide; and / or, along the direction from the tunnel layer to the substrate, the thickness of the diffusion barrier layer is 0.5 nm to 10 nm.

5. The photovoltaic cell according to claim 1, characterized in that: Along the direction from the tunneling layer to the substrate, the thickness of the nitrogen-phosphorus co-doped polysilicon layer is less than the thickness of the phosphorus-doped polysilicon layer.

6. A method for manufacturing a photovoltaic cell, characterized in that: include: providing a substrate, and forming a tunneling layer on a back side of the substrate; forming a first silicon material layer on a side of the tunneling layer away from the substrate; Performing nitrogen doping treatment on the first silicon material layer to convert the first silicon material layer into a nitrogen-doped layer; forming a diffusion barrier film on a side of the nitrogen-doped layer away from the tunneling layer; forming a second silicon material layer on a side of the diffusion barrier film away from the nitrogen-doped layer; The nitrogen-doped layer, the diffusion barrier film and the second silicon material layer are integrally subjected to phosphorus doping treatment to convert the nitrogen-doped layer into a nitrogen-phosphorus co-doped polysilicon layer, convert the diffusion barrier film into a diffusion barrier layer, and convert the second silicon material layer into a phosphorus-doped polysilicon layer.

7. The method for manufacturing a photovoltaic cell according to claim 6, characterized in that: The step of performing the nitrogen doping treatment on the first silicon material layer includes: treating the first silicon material layer with plasma ammonia gas, so that nitrogen elements and hydrogen elements are doped into the first silicon material layer.

8. The method for manufacturing a photovoltaic cell according to claim 6, characterized in that: In the step of performing the phosphorus doping treatment, based on the barrier effect of the diffusion barrier film on phosphorus, the doping concentration of phosphorus in the nitrogen-doped layer closer to the substrate is lower.

9. The method for manufacturing a photovoltaic cell according to claim 6, characterized in that: The first silicon material layer and the second silicon material layer are both amorphous silicon; The steps of performing the phosphorus doping process include: forming a phosphorus-doped source layer on a side of the second silicon material layer away from the diffusion barrier film; Annealing treatment is performed to diffuse the phosphorus element in the phosphorus doping source layer into the second silicon material layer, the diffusion barrier film and the nitrogen doping layer in sequence, and to convert the first silicon material layer and the second silicon material layer into polysilicon.

10. A photovoltaic module, characterized in that: include: A cell string formed by connecting a plurality of photovoltaic cells according to any one of claims 1 to 5, or by connecting a plurality of photovoltaic cells formed by the method for manufacturing a photovoltaic cell according to any one of claims 6 to 9; A packaging film, used to cover the surface of the battery string; The cover plate is used to cover the surface of the packaging film facing away from the battery string.

Images