Solar cell

Abstract

The utility model discloses a solar cell, which is applied to the field of photovoltaic power generation and comprises a substrate, and a first tunneling layer, a first doped polycrystalline silicon layer and a second doped polycrystalline silicon layer which are sequentially arranged outwards along the surface of the substrate, the first doped polycrystalline silicon layer and the second doped polycrystalline silicon layer have the same doping type and are both doped with an N-type dopant or a P-type dopant; besides an N-type dopant or a P-type dopant, the first doped polycrystalline silicon layer is additionally doped with at least one element of carbon, nitrogen and oxygen. At least one element of carbon, nitrogen and oxygen is additionally doped in the first doped polycrystalline silicon layer close to the substrate, the second doped polycrystalline silicon layer which is not doped with any one element of carbon, nitrogen and oxygen is arranged on the outer side of the first doped polycrystalline silicon layer, and the doping type of the first doped polycrystalline silicon layer is the same as that of the second doped polycrystalline silicon layer. The current conductivity of the passivation layer can be improved while the parasitic absorption effect of the passivation layer is reduced in a balanced manner.

Description

Technical Field

[0001] The utility model relates to the field of photovoltaic power generation, in particular to a solar cell. Background Art

[0002] The TOPCon (Tunneling Oxide Passivation Contact) structure provides high passivation quality, achieving high open-circuit voltage and improving photoelectric conversion efficiency. However, in existing cells based on the TOPCon passivation structure, the polysilicon layer is relatively thick, resulting in excessive parasitic absorption, which affects cell performance. Existing attempts have been made to reduce this parasitic absorption by doping the polysilicon layer with elements such as carbon, nitrogen, and oxygen. However, this approach leads to poor contact with the conductive electrode, reducing current extraction efficiency.

[0003] Therefore, how to provide a method that can reduce the parasitic absorption effect of the polysilicon layer while reducing the impact on the current extraction efficiency is a technical problem that those skilled in the art urgently need to solve. Utility Model Content

[0004] In view of this, the purpose of the present invention is to provide a solar cell that solves the problem in the prior art that the polysilicon layer is doped with elements such as carbon, nitrogen, and oxygen, resulting in poor contact with the conductive electrode and reduced current extraction efficiency.

[0005] In order to solve the above technical problems, the present invention provides a solar cell, comprising:

[0006] A substrate, a first tunneling layer, a first doped polysilicon layer, and a second doped polysilicon layer sequentially arranged outwardly along a surface of the substrate;

[0007] The first doped polysilicon layer and the second doped polysilicon layer have the same doping type, and are both doped with N-type dopants or P-type dopants;

[0008] In addition to the N-type dopant or the P-type dopant, the first doped polysilicon layer is additionally doped with at least one element selected from the group consisting of carbon, nitrogen, and oxygen.

[0009] Optionally, the doping type of the first doped polysilicon layer and the second doped polysilicon layer is the same as the doping type of the substrate, and the doping concentration of the first doped polysilicon layer and the second doped polysilicon layer is greater than the doping concentration of the substrate.

[0010] Optionally, the doping type of the first doped polysilicon layer and the second doped polysilicon layer is different from the doping type of the substrate.

[0011] Optionally, the first tunneling layer, the first doped polysilicon layer, and the second doped polysilicon layer are provided outwardly on both the front and back surfaces of the substrate; the first doped polysilicon layer and the second doped polysilicon layer have the same doping type, both being doped with an N-type dopant or a P-type dopant; and the first doped polysilicon layer is doped with at least one element selected from carbon, nitrogen, and oxygen in addition to the N-type dopant or the P-type dopant;

[0012] The doping type of the first doped polysilicon layer and the second doped polysilicon layer located on the front side of the substrate is different from the doping type of the first doped polysilicon layer and the second doped polysilicon layer located on the back side of the substrate.

[0013] Optionally, it further includes a conductive electrode electrically connected to the second doped polysilicon layer; and / or,

[0014] The second doped polysilicon layer includes multiple layers of second sub-doped polysilicon layers, and the doping concentration of the second sub-doped polysilicon layers gradually increases along a direction facing away from the substrate.

[0015] Optionally, a ratio of the thickness of the first doped polysilicon layer to the thickness of the second doped polysilicon layer is in a range of 1:1 to 2:1.

[0016] Optionally, the thickness of the first doped polysilicon layer and the thickness of the second doped polysilicon layer are both greater than 5 nanometers and less than 200 nanometers;

[0017] The total thickness of the first doped polysilicon layer and the second doped polysilicon layer is less than 200 nanometers.

[0018] Optionally, the thickness of the first tunneling layer is 0.5 nanometers to 10 nanometers.

[0019] Optionally, the projection of the second doped polysilicon layer on the substrate corresponds to an electrode region; or,

[0020] Projections of the first tunneling layer, the first doped polysilicon layer, and the second doped polysilicon layer on the substrate correspond to electrode regions.

[0021] Optionally, a second tunneling layer is provided on a side of the second doped polysilicon layer close to the first doped polysilicon layer.

[0022] It can be seen that the solar cell provided by the present invention includes a substrate, a first tunneling layer, a first doped polysilicon layer and a second doped polysilicon layer arranged in sequence along the surface of the substrate outward, the first doped polysilicon layer and the second doped polysilicon layer have the same doping type, and are both doped with N-type dopants or P-type dopants. In addition to the N-type dopant or the P-type dopant, the first doped polysilicon layer is additionally doped with at least one element of carbon, nitrogen and oxygen. The present invention improves the passivation effect while reducing recombination by additionally doping at least one element among carbon, nitrogen and oxygen in the first doped polysilicon layer close to the substrate, which can reduce the parasitic absorption effect caused by the doped polysilicon layer close to the substrate in the prior art, and by arranging a second doped polysilicon layer that is not doped with any of carbon, nitrogen and oxygen on the outside of the first doped polysilicon layer, and setting the first doped polysilicon layer and the second doped polysilicon layer to have the same doping type, it can optimize the contact effect between the polysilicon layer and the conductive electrode, improve the body resistance and contact resistance, reduce the series resistance, and increase the FF (fill factor); therefore, the present application improves the current conductivity of the passivation layer while evenly reducing the parasitic absorption effect of the passivation layer, thereby improving the battery efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0024] Figure 1 A schematic structural diagram of a solar cell provided in an embodiment of the present utility model;

[0025] Figure 2 A schematic structural diagram of another solar cell provided by an embodiment of the present utility model;

[0026] Figure 3 A schematic structural diagram of another solar cell provided in an embodiment of the present utility model;

[0027] Figure 4 A schematic structural diagram of a solar cell including a stacked tunnel junction provided by an embodiment of the present utility model;

[0028] Figures 1 to 4 In the figure, the reference numerals are described as follows:

[0029] 10 - substrate, 20 - first tunneling layer, 30 - first doped polysilicon layer, 40 - second doped polysilicon layer, 50 - conductive electrode, 60 - second tunneling layer. DETAILED DESCRIPTION

[0030] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0031] Example 1:

[0032] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a solar cell provided by an embodiment of the present invention. The solar cell may include:

[0033] A substrate 10, a first tunneling layer 20, a first doped polysilicon layer 30, and a second doped polysilicon layer 40 sequentially arranged outwardly from a surface of the substrate 10;

[0034] The first doped polysilicon layer 30 and the second doped polysilicon layer 40 have the same doping type, and are both doped with N-type dopants or P-type dopants;

[0035] In addition to the N-type dopant or the P-type dopant, the first doped polysilicon layer 30 is additionally doped with at least one element selected from the group consisting of carbon, nitrogen, and oxygen.

[0036] It should be noted that, unlike conventional tunnel junction passivation structures, this embodiment employs a polysilicon layer doped with at least one of carbon, nitrogen, and oxygen, as a first doped polysilicon layer 30, disposed outside the tunneling layer. Doping with at least one of carbon, nitrogen, and oxygen reduces parasitic absorption of light by the polysilicon layer, thereby improving the photovoltaic conversion efficiency of the cell. However, doping the polysilicon layer with elements such as carbon, nitrogen, and oxygen can negatively impact its conductivity, resulting in poor contact with the conductive electrode 50 and lowering current extraction efficiency. Therefore, in this embodiment, a second doped polysilicon layer 40, located outside the first doped polysilicon layer 30, is provided as a polysilicon layer undoped with any of carbon, nitrogen, and oxygen. This improved electrical contact between the second doped polysilicon layer 40 and the conductive electrode 50 improves current extraction efficiency. In addition, it should be noted that in order to ensure the conductive effect of the polysilicon layer, it is necessary to dope N-type doping impurities or P-type doping impurities in the polysilicon layer. In order to ensure the overall current extraction effect of the above-mentioned first doped polysilicon layer 30 and the second doped polysilicon layer 40, and at the same time ensure the convenience of preparing the first doped polysilicon layer 30 and the second doped polysilicon layer 40, the doping types of the first doped polysilicon layer 30 and the second doped polysilicon layer 40 are set to be the same, that is, the first doped polysilicon layer 30 and the second doped polysilicon layer 40 are both doped with P-type doping impurities, or both doped with N-type doping impurities, which can improve the body resistance and contact resistance, reduce the series resistance, increase FF, and optimize the contact effect between the polysilicon layer and the conductive electrode 50.

[0037] This embodiment does not limit the types and quantities of carbon, nitrogen, and oxygen doped in the first doped polysilicon layer 30. Only one of carbon, nitrogen, and oxygen may be doped, or all of the above carbon, nitrogen, and oxygen may be doped simultaneously. The specific doping content may be set according to actual preparation requirements.

[0038] To make the solar cell of the present invention easier to understand, a method for preparing the solar cell may include the following steps:

[0039] Step 1: Provide a silicon substrate 10.

[0040] The silicon substrate 10 provided in this embodiment may be a silicon substrate 10 doped with P-type dopant impurities or N-type dopant impurities.

[0041] Step 2: Prepare a first tunneling layer 20 on the surface of the silicon substrate 10 .

[0042] In this embodiment, the first tunneling layer 20 can be prepared using equipment such as PECVD (plasma enhanced chemical vapor deposition) or LPCVD (low pressure chemical vapor deposition), and the thickness can be controlled to be between 0.5 nanometers and 10 nanometers.

[0043] Step 3: preparing a first doped polysilicon layer 30 on the surface of the first tunneling layer 20 , wherein the first doped polysilicon layer 30 is doped with at least one element selected from the group consisting of carbon, nitrogen, and oxygen.

[0044] The first doped polysilicon layer 30 is arranged on the side of the first tunneling layer 20 facing away from the silicon substrate 10, and in this embodiment, the first doped polysilicon layer 30 can be prepared using equipment such as PECVD or LPCVD, and the thickness can be set to 5 nanometers to 200 nanometers. During the preparation, the reaction gas source can be carbon tetrafluoride, carbon dioxide, carbon monoxide, ammonia, silane, phosphine, diborane, hydrogen, etc.

[0045] Step 4: preparing a second doped polysilicon layer 40 on the surface of the first doped polysilicon layer 30 . The first doped polysilicon layer 30 and the second doped polysilicon layer 40 have the same doping type, thereby completing the preparation of the above solar cell.

[0046] The second doped polysilicon layer 40 is arranged on the side of the first doped polysilicon layer 30 facing away from the silicon substrate 10, and in this embodiment, the second doped polysilicon layer 40 can be prepared using equipment such as PECVD or LPCVD, and the thickness can be set to 5 nanometers to 200 nanometers. During the preparation, the reaction gas source can be selected from silane, phosphine, diborane, hydrogen, etc.

[0047] Furthermore, in order to ensure the simplicity of the solar cell structure and the convenience of preparation, the doping type of the above-mentioned first doped polysilicon layer 30 and the second doped polysilicon layer 40 can be set to be the same as the doping type of the substrate 10, and the doping concentration of the first doped polysilicon layer 30 and the second doped polysilicon layer 40 can be greater than the doping concentration of the substrate 10.

[0048] It should be noted that in order to prevent carrier recombination on the surface of the silicon substrate 10 and improve the efficiency of extracting the collected photogenerated current, the above-mentioned silicon substrate 10, the first doped polysilicon layer 30 and the second doped polysilicon layer 40 are set to the same doping type, and the doping concentration of the first doped polysilicon layer 30 and the second doped polysilicon layer 40 is set to be greater than the doping concentration of the substrate 10, thereby forming a high-low junction in the solar cell. Benefiting from the higher electron mobility of the high-low junction, the current extraction efficiency is improved.

[0049] Furthermore, in order to maximize the photoelectric conversion efficiency of solar cells, we can refer to Figure 2 , Figure 2A schematic diagram of the structure of another solar cell provided by an embodiment of the present invention. A first tunneling layer 20, a first doped polysilicon layer 30, and a second doped polysilicon layer 40 can be provided on both the front and back surfaces of the substrate 10. The first doped polysilicon layer 30 and the second doped polysilicon layer 40 have the same doping type, both doped with N-type dopants or P-type dopants. In addition to the N-type dopants or P-type dopants, the first doped polysilicon layer 30 is additionally doped with at least one element selected from carbon, nitrogen, and oxygen.

[0050] The doping type of the first doped polysilicon layer 30 and the second doped polysilicon layer 40 on the front side of the substrate 10 is different from the doping type of the first doped polysilicon layer 30 and the second doped polysilicon layer 40 on the back side of the substrate 10 .

[0051] It should be noted that in this embodiment, by arranging a stacked structure formed by a first tunneling layer 20, a first doped polysilicon layer 30 and a second doped polysilicon layer 40 on both sides of the substrate 10, the photoelectric conversion efficiency of the solar cell can be further improved, and the parasitic absorption of the polysilicon layer on both the front and back sides of the cell can be reduced, while ensuring good conductive contact between the polysilicon layer and the conductive electrode 50. In addition, it should be noted that, in this embodiment, the doping type of the first doped polysilicon layer 30 and the second doped polysilicon layer 40 located on the front side of the substrate 10 is set to be different from the doping type of the first doped polysilicon layer 30 and the second doped polysilicon layer 40 located on the back side of the substrate 10, which means that in this application, the doping type of the polysilicon layers located on both sides of the substrate 10 needs to be set to N-type doping on one side and P-type doping on the other side, that is, the stacked structure formed by the first tunneling layer 20, the first doped polysilicon layer 30 and the second doped polysilicon layer 40 located on the front side of the substrate 10 is not exactly the same as the stacked structure formed by the first tunneling layer 20, the first doped polysilicon layer 30 and the second doped polysilicon layer 40 located on the back side of the substrate 10, and the doping types of the two are different.

[0052] Furthermore, in order to ensure the smooth preparation of solar cells, you can refer to Figure 3 , Figure 3 A schematic diagram of the structure of another solar cell provided by an embodiment of the present invention. It may further include a conductive electrode 50 electrically connected to the second doped polysilicon layer 40; and / or,

[0053] The second doped polysilicon layer 40 includes multiple layers of second sub-doped polysilicon layers, and the doping concentration of the second sub-doped polysilicon layers gradually increases in a direction facing away from the substrate 10 .

[0054] It should be noted that in this embodiment, the conductive electrode 50 is fabricated in contact with the second doped polysilicon layer 40 to ensure smooth extraction of the photocurrent collected by solar energy. This embodiment does not limit the method for fabricating the conductive electrode 50; reference can be made to the fabrication of the conductive electrode 50 in existing solar cells. Furthermore, in this embodiment, the doping concentration of the multilayer second sub-doped polysilicon layer can be configured to increase in a gradient, for example, arithmetic progression, in the direction away from the substrate 10. However, it should be noted that the smaller the variation in doping concentration between adjacent layers in the multilayer second sub-doped polysilicon layer, the more effectively it can hinder the inward diffusion of dopant impurities.

[0055] Furthermore, in order to ensure that the parasitic absorption of the entire doped polysilicon layer is improved, and at the same time to evenly improve the contact effect between the polysilicon layer doped with impurities such as carbon, nitrogen, and oxygen and the conductive electrode 50, the ratio of the thickness of the first doped polysilicon layer 30 to the thickness of the second doped polysilicon layer 40 can be set to be in the range of 1:1 to 2:1.

[0056] It should be noted that, in this embodiment, by setting the ratio of the thickness of the first doped polysilicon layer 30 to the thickness of the second doped polysilicon layer 40 to be within the range of 1:1 to 2:1, in the structure of the first doped polysilicon layer 30 and the second doped polysilicon layer 40 that ensure this ratio relationship, the diffusion of doping impurities such as carbon, nitrogen, and oxygen in the first doped polysilicon layer 30 does not excessively affect the electrical contact between the second doped polysilicon layer 40 and the conductive electrode 50. The second doped polysilicon layer 40 with a specified thickness can improve the electrical contact effect with the conductive electrode 50 while ensuring low parasitic absorption, thereby facilitating current extraction.

[0057] Furthermore, in order to ensure the passivation effect of the polysilicon layer and avoid the polysilicon layer being too thick, so as to comprehensively ensure the functionality of the polysilicon layer, the thickness of the first doped polysilicon layer 30 and the thickness of the second doped polysilicon layer 40 can be set to be greater than 5 nanometers and less than 200 nanometers.

[0058] The total thickness of the first doped polysilicon layer 30 and the second doped polysilicon layer 40 is less than 200 nanometers.

[0059] It should be noted that in this embodiment, the thickness of the first doped polysilicon layer 30 and the thickness of the second doped polysilicon layer 40 are both set to be greater than 5 nanometers and less than 200 nanometers. At the same time, the total thickness of the two is less than 200 nanometers. While ensuring the passivation effect of the overall polysilicon layer, it can ensure the current extraction effect and optimize the parasitic absorption effect of the polysilicon layer.

[0060] Furthermore, in order to ensure the normal operation of the solar cell, the thickness of the first tunneling layer 20 can be set to be 0.5 nanometers to 10 nanometers.

[0061] In this embodiment, the thickness of the first tunneling layer 20 is set to 0.5 nanometers to 10 nanometers to prevent the solar cell from being short-circuited and ensure the normal operation of the battery.

[0062] Furthermore, in order to reduce the parasitic adsorption generated by the polysilicon layer in the prepared solar cell, the projection of the second doped polysilicon layer 40 on the substrate 10 may be arranged to correspond to the electrode region; or,

[0063] The projections of the first tunneling layer 20 , the first doped polysilicon layer 30 , and the second doped polysilicon layer 40 on the substrate 10 correspond to the electrode region.

[0064] It should be noted that in this embodiment, the second doped polysilicon layer 40 is disposed in the electrode region corresponding to the projection of the substrate 10. That is, the second doped polysilicon layer 40 is disposed only in the electrode contact region and is not disposed in the non-electrode region. That is, the use of a polysilicon layer undoped with any element such as carbon, nitrogen, or oxygen is avoided in the non-electrode region, thereby improving the photovoltaic conversion efficiency of the cell and ensuring the current extraction efficiency in the electrode region. To ensure fabrication accuracy, the projection of the first tunneling layer 20, the first doped polysilicon layer 30, and the second doped polysilicon layer 40 on the substrate 10 may also correspond to the electrode region.

[0065] It should be noted that, in a possible embodiment, the doping type of the first doped polysilicon layer 30 and the second doped polysilicon layer 40 may be different from the doping type of the substrate 10 .

[0066] In this embodiment, the doping type of the first doped polysilicon layer 30 and the second doped polysilicon layer 40 is different from the doping type of the substrate 10, so that a PN junction can be formed between the doped polysilicon and the substrate 10, which can facilitate preparation while ensuring the stability of the operation of the solar cell.

[0067] The solar cell provided by the embodiment of the present invention includes a substrate 10, a first tunneling layer 20, a first doped polysilicon layer 30, and a second doped polysilicon layer 40, which are arranged in sequence outward from the surface of the substrate 10. The first doped polysilicon layer 30 and the second doped polysilicon layer 40 have the same doping type and are both doped with N-type dopants or P-type dopants. In addition to the N-type dopant or the P-type dopant, the first doped polysilicon layer 30 is additionally doped with at least one element of carbon, nitrogen, and oxygen. The present invention improves the passivation effect while reducing recombination by additionally doping at least one element of carbon, nitrogen, and oxygen in the first doped polysilicon layer 30 close to the substrate, thereby reducing the parasitic absorption effect caused by the doped polysilicon layer close to the substrate 10 in the prior art. In addition, by additionally providing a second doped polysilicon layer 40 that is not doped with any of carbon, nitrogen, and oxygen on the outside of the first doped polysilicon layer 30, and setting the first doped polysilicon layer 30 and the second doped polysilicon layer 40 to have the same doping type, the contact effect between the polysilicon layer and the conductive electrode 50 can be optimized, the body resistance and contact resistance can be improved, the series resistance can be reduced, and the FF (fill factor) can be increased. Therefore, the present application improves the current conductivity of the passivation layer while evenly reducing the parasitic absorption effect of the passivation layer, thereby improving the battery efficiency.

[0068] In addition, the embodiment of the present invention sets the silicon substrate 10, the first doped polysilicon layer 30 and the second doped polysilicon layer 40 to have the same doping type and forms a high-low junction, which benefits from the higher electron mobility of the high-low junction and improves the current extraction efficiency; by setting a stacked structure formed by the first tunneling layer 20, the first doped polysilicon layer 30 and the second doped polysilicon layer 40 on both sides of the substrate 10, and the doping type of the first doped polysilicon layer 30 and the second doped polysilicon layer 40 located on the front side of the substrate 10 is different from the doping type of the first doped polysilicon layer 30 and the second doped polysilicon layer 40 located on the back side of the substrate 10, the photoelectric conversion efficiency of the solar cell can be further improved, the parasitic absorption of the polysilicon layer on both the front and back sides of the cell can be reduced, and at the same time, good conductive contact between the polysilicon layer and the conductive electrode 50 is ensured; the conductive electrode 50 is electrically connected to the second doped polysilicon layer 40 to ensure that the photogenerated current collected by solar energy is smoothly conducted. The doping concentration of the multi-layer second sub-doped polysilicon layer is set to gradually increase in the direction back to the substrate 10, thereby ensuring a passivation contact effect while preventing dopant impurities in the doped polysilicon layer from diffusing inwardly. By setting the ratio of the thickness of the first doped polysilicon layer 30 to the thickness of the second doped polysilicon layer 40 to be within the range of 1:1 to 2:1, while ensuring low parasitic absorption of the polysilicon layer, the electrical contact effect with the conductive electrode 50 is improved, thereby facilitating current extraction. The thickness of the first doped polysilicon layer 30 and the thickness of the second doped polysilicon layer 40 are both set to be greater than 5 nanometers and less than 200 nanometers, and the total thickness of the two is less than 200 nanometers. This can ensure the passivation effect of the entire polysilicon layer while ensuring the current extraction effect and optimizing the parasitic absorption effect of the polysilicon layer. The thickness of the first tunneling layer 20 is set to 0.5 nanometers to 10 nanometers to avoid breakdown short circuit in the solar cell and ensure normal operation of the battery.

[0069] In another embodiment of the present invention, a second doped polysilicon layer 40 is provided on the projection of the substrate 10 corresponding to the electrode area; the second doped polysilicon layer 40 is provided only in the electrode area, but not in the non-electrode area, so that the parasitic absorption caused by the second doped polysilicon layer 40 (when the second doped polysilicon layer 40 is on the back) and the metal contact area recombination caused by the second doped polysilicon layer 40 (front) can be reduced, and the shading effect caused by the second doped polysilicon layer 40 can be reduced; thereby, the passivation layer covers the non-electrode area of the first doped polysilicon layer 30 and the electrode area of the second doped polysilicon layer 40 at the same time, thereby improving the battery efficiency.

[0070] In another embodiment of the present invention, the projections of the first tunneling layer 20, the first doped polysilicon layer 30 and the second doped polysilicon layer 40 on the substrate 10 correspond to the electrode region. In this embodiment, a passivation layer having a passivation effect better than that of the first doped polysilicon layer 30 can be covered on the non-electrode region, thereby further reducing the parasitic adsorption and recombination generated by the polysilicon layer (the first doped polysilicon layer 30 and the second doped polysilicon layer 40) in the prepared solar cell, reducing its shading effect, and improving the cell efficiency.

[0071] Example 2:

[0072] Please refer to Figure 4 , Figure 4 A schematic diagram of the structure of a solar cell including a stacked tunnel junction according to an embodiment of the present invention is provided. Compared to Example 1, this solar cell differs in that a second tunnel layer 60 is provided on the side of the second doped polysilicon layer 40 close to the first doped polysilicon layer 30 .

[0073] It should be noted that in this embodiment, a second tunneling layer 60 is provided between the first doped polysilicon layer 30 and the second doped polysilicon layer 40, which can further prevent the carbon, nitrogen, oxygen and other impurities doped in the first doped polysilicon layer 30 from diffusing into the second doped polysilicon layer 40, thereby ensuring the benign conductive contact between the second doped polysilicon layer 40 and the conductive electrode 50, thereby improving the current extraction efficiency of the solar cell.

[0074] The solar cell provided by the embodiment of the present invention can prevent impurities such as carbon, nitrogen, and oxygen from diffusing into the second doped polysilicon layer 40 by providing a second tunneling layer 60 between the first doped polysilicon layer 30 and the second doped polysilicon layer 40, thereby improving the current extraction efficiency of the solar cell.

[0075] In an application scenario embodiment, the solar cell may specifically include the following steps:

[0076] A substrate 10, a first tunneling layer 20, a first doped polysilicon layer 30, a second tunneling layer 60, and a second doped polysilicon layer 40 are sequentially arranged outward from the surface of the substrate 10; and a conductive electrode 50 electrically connected to the second doped polysilicon layer 40;

[0077] The first doped polysilicon layer 30 and the second doped polysilicon layer 40 have the same doping type, and are both doped with N-type dopants or P-type dopants;

[0078] The first doped polysilicon layer 30 is doped with at least one element of carbon, nitrogen, and oxygen in addition to the N-type dopant or the P-type dopant;

[0079] The doping type of the first doped polysilicon layer 30 and the second doped polysilicon layer 40 is the same as the doping type of the substrate 10 , and the doping concentration of the first doped polysilicon layer 30 and the second doped polysilicon layer 40 is greater than the doping concentration of the substrate 10 ;

[0080] A first tunneling layer 20, a first doped polysilicon layer 30, and a second doped polysilicon layer 40 are provided on both the front and back surfaces of the substrate 10. The doping type of the first doped polysilicon layer 30 and the second doped polysilicon layer 40 on the front side of the substrate 10 is different from the doping type of the first doped polysilicon layer 30 and the second doped polysilicon layer 40 on the back side of the substrate 10.

[0081] The ratio of the thickness of the first doped polysilicon layer 30 to the thickness of the second doped polysilicon layer 40 is within a range of 1:1 to 2:1; the thickness of the first doped polysilicon layer 30 and the thickness of the second doped polysilicon layer 40 are both greater than 5 nanometers and less than 200 nanometers; the total thickness of the first doped polysilicon layer 30 and the second doped polysilicon layer 40 is less than 200 nanometers; the thickness of the first tunneling layer 20 is 0.5 nanometers to 10 nanometers;

[0082] The second doped polysilicon layer 40 includes multiple layers of second sub-doped polysilicon layers; the doping concentration of the second sub-doped polysilicon layers gradually increases in a direction back to the substrate 10;

[0083] The projection of the second doped polysilicon layer 40 on the substrate 10 corresponds to the electrode region; or the projection of the first tunneling layer 20 , the first doped polysilicon layer 30 and the second doped polysilicon layer 40 on the substrate 10 corresponds to the electrode region.

[0084] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0085] In addition, it should be noted that, in this document, relationships such as first and second, etc., are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include," "comprises," or any other variations thereof are intended to cover non-exclusive inclusion.

[0086] The above is a detailed introduction to a solar cell provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the structure and core concept of the present invention. At the same time, for those skilled in the art, according to the concept of the present invention, there may be changes in the specific implementation methods and application scope. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A solar cell, characterized in that: include: A substrate, a first tunneling layer, a first doped polysilicon layer, and a second doped polysilicon layer sequentially arranged outwardly along a surface of the substrate; The first doped polysilicon layer and the second doped polysilicon layer have the same doping type, and are both doped with N-type dopants or P-type dopants; In addition to the N-type dopant or the P-type dopant, the first doped polysilicon layer is additionally doped with at least one element selected from the group consisting of carbon, nitrogen, and oxygen.

2. The solar cell according to claim 1, wherein: The doping type of the first doped polysilicon layer and the second doped polysilicon layer is the same as the doping type of the substrate, and the doping concentration of the first doped polysilicon layer and the second doped polysilicon layer is greater than the doping concentration of the substrate.

3. The solar cell according to claim 1, wherein The doping type of the first doped polysilicon layer and the second doped polysilicon layer is different from the doping type of the substrate.

4. The solar cell according to claim 1, wherein The first tunneling layer, the first doped polysilicon layer, and the second doped polysilicon layer are disposed outwardly on both the front and back surfaces of the substrate; the first doped polysilicon layer and the second doped polysilicon layer have the same doping type, both being doped with an N-type dopant or a P-type dopant; the first doped polysilicon layer is doped with at least one element selected from carbon, nitrogen, and oxygen in addition to the N-type dopant or the P-type dopant; The doping type of the first doped polysilicon layer and the second doped polysilicon layer located on the front side of the substrate is different from the doping type of the first doped polysilicon layer and the second doped polysilicon layer located on the back side of the substrate.

5. The solar cell according to claim 1, wherein: further comprising a conductive electrode electrically connected to the second doped polysilicon layer; and / or, The second doped polysilicon layer includes multiple layers of second sub-doped polysilicon layers, and the doping concentration of the second sub-doped polysilicon layers gradually increases along a direction facing away from the substrate.

6. The solar cell according to claim 1, wherein A ratio of a thickness of the first doped polysilicon layer to a thickness of the second doped polysilicon layer is in a range of 1:1 to 2:

1.

7. The solar cell according to claim 6, characterized in that The thickness of the first doped polysilicon layer and the thickness of the second doped polysilicon layer are both greater than 5 nanometers and less than 200 nanometers; The total thickness of the first doped polysilicon layer and the second doped polysilicon layer is less than 200 nanometers.

8. The solar cell according to claim 7, characterized in that The thickness of the first tunneling layer is 0.5 nanometers to 10 nanometers.

9. The solar cell according to claim 1, wherein: The projection of the second doped polysilicon layer on the substrate corresponds to the electrode region; or, Projections of the first tunneling layer, the first doped polysilicon layer, and the second doped polysilicon layer on the substrate correspond to electrode regions.

10. The solar cell according to any one of claims 1 to 9, characterized in that A second tunneling layer is provided on a side of the second doped polysilicon layer close to the first doped polysilicon layer.

Images