Photovoltaic cell and manufacturing method thereof

Abstract

The embodiment of the invention relates to the photovoltaic field, and provides a photovoltaic cell and a manufacturing method thereof, and the photovoltaic cell comprises a substrate, the first surface of the substrate is provided with a first region and a second region which are alternately arranged along a first direction; the tunneling layer is located in the first region and the second region; the first polycrystalline silicon layer is located on the side, away from the substrate, of the tunneling layer; the protection layer is positioned on one side, far away from the substrate, of the first polycrystalline silicon layer; the second polycrystalline silicon layer is located on the first region and located on the side, away from the first polycrystalline silicon layer, of the protection layer; wherein the first polycrystalline silicon layer and the second polycrystalline silicon layer are doped with the same doping element, and the ratio of the doping concentration of the doping element in the first polycrystalline silicon layer to the doping concentration of the doping element in the second polycrystalline silicon layer is 0.9-1.1; and an electrode on the first region, wherein the electrode is in electrical contact with the second polycrystalline silicon layer. The embodiment of the invention is at least beneficial to improving the photoelectric conversion efficiency of the photovoltaic cell.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to the field of photovoltaics, and in particular, to a photovoltaic cell and a manufacturing method thereof. Background Art

[0002] With the gradual depletion of fossil energy, photovoltaic cells, as a new energy alternative, are being used more and more widely. A photovoltaic cell is a device that converts the light energy of the sun into electrical energy. The photovoltaic cell utilizes the photovoltaic effect principle to generate carriers, and then uses electrodes to lead out the carriers, thereby facilitating the effective utilization of electrical energy.

[0003] Current photovoltaic cells mainly include IBC cells (Interdigitated BackContact), TOPCON (Tunnel Oxide Passivated Contact) cells, PERC cells (Passivated emitter and real cell), and heterojunction cells, etc. By setting different film layers and functional limitations, optical losses are reduced and the recombination of photo-generated carriers on and in the silicon substrate surface is reduced to improve the photoelectric conversion efficiency of the solar cell.

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

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

[0006] According to some embodiments of the present disclosure, on the one hand, an embodiment of the present disclosure provides a photovoltaic cell, including: a substrate, a first surface of the substrate having a first region and a second region alternately arranged along a first direction; a tunneling layer located in the first region and the second region; a first polysilicon layer located on a side of the tunneling layer away from the substrate; a protective layer located on the first region, the protective layer being located on a side of the first polysilicon layer away from the substrate; a second polysilicon layer located on the first region, the second polysilicon layer being located on a side of the protective layer away from the first polysilicon layer; an electrode located on the first region, the electrode being in electrical contact with the second polysilicon layer; wherein, the first polysilicon layer and the second polysilicon layer are doped with the same doping element, and a ratio of doping concentrations of the doping element in the first polysilicon layer and the second polysilicon layer is 0.9 to 1.1.

[0007] In some embodiments, the material of the protective layer includes at least one of metal nitride or metal oxide.

[0008] In some embodiments, along the second direction, the second thickness of the protective layer is less than the first thickness of the first polysilicon layer, and the first thickness of the first polysilicon layer is less than or equal to the third thickness of the second polysilicon layer. The second direction is the direction from the first polysilicon layer to the second polysilicon layer.

[0009] In some embodiments, the ratio of the second thickness to the first thickness is 0.007 to 0.075; and / or, the ratio of the first thickness to the third thickness is 0.15 to 1.

[0010] In some embodiments, the doping element is also doped in the protective layer, and the doping concentration of the doping element in the second polysilicon layer, the protective layer, and the first polysilicon layer decreases in sequence.

[0011] According to some embodiments of the present disclosure, on the other hand, the present disclosure also provides a method for manufacturing a photovoltaic cell, including: providing a substrate, the first surface of the substrate having a first region and a second region arranged alternately along a first direction; forming a tunneling layer on the first surface; forming a stacked first polysilicon film, a protective film, and a second polysilicon film on a side of the tunneling layer away from the substrate. The first polysilicon film and the second polysilicon film are doped with the same doping element, and the ratio of the doping concentration of the doping element in the first polysilicon film to the doping concentration in the second polysilicon film is 0.9 to 1.1; using the protective film located in the second region as an etch stop layer, performing a first etching process on the second polysilicon film located in the second region, and exposing the protective film located in the second region, and the remaining second polysilicon film located in the first region serves as a second polysilicon layer; using the second polysilicon layer as a mask, performing a second etching process on the exposed protective film to remove the protective film located in the second region, and the remaining protective film serves as a protective layer, and the exposed first polysilicon film and the unexposed first polysilicon film together serve as a first polysilicon layer.

[0012] In some embodiments, in the step of forming the stacked first polysilicon film, the protective film, and the second polysilicon film, an oxide layer is further formed on a side of the second polysilicon film away from the protective film; before performing the first etching process, the manufacturing method further includes: selectively etching the oxide layer to remove the oxide layer located in the second region; in the step of performing the first etching process, not only using the protective film located in the second region as an etch stop layer, but also using the remaining oxide layer located in the first region as a mask to remove the second polysilicon film located in the second region; in the step of performing the second etching process, the oxide layer located in the first region is further removed.

[0013] In some embodiments, the step of selectively etching the oxide layer includes: using a laser to remove the oxide layer located in the second region.

[0014] In some embodiments, the step of forming the stacked first polysilicon film, the protective film, and the second polysilicon film includes: sequentially forming a first silicon material layer, an initial protective layer, and a second silicon material layer on a side of the tunneling layer away from the substrate; doping the first silicon material layer, the initial protective layer, and the second silicon material layer to form the first polysilicon film, the protective film, and the second polysilicon film doped with the same element.

[0015] In some embodiments, the step of forming the initial protective layer may include: forming the initial protective layer by a deposition process.

[0016] The technical solutions provided by the embodiments of the present disclosure have at least the following advantages:

[0017] Design the ratio of the doping concentration of the doping element in the first polysilicon layer and the second polysilicon layer to be 0.9 to 1.1, then the doping concentrations of the doping element in the first polysilicon layer and the second polysilicon layer are similar, which is beneficial to reducing the resistivity of the entire passivation stack composed of the first polysilicon layer, the protective layer, and the second polysilicon layer located in the first region, thereby reducing the transport resistance of carriers in the passivation stack to improve the collection efficiency of the photovoltaic cell for carriers. In addition, different from the first region where there are two polysilicon layers, there is only one polysilicon layer on the second region. On the one hand, it is beneficial to use the first polysilicon layer located on the entire first surface to passivate both the second region and the first region well to reduce the density of defect states on the entire first surface. Compared with directly depositing an alumina layer on the second region for passivation, the fixed negative charges in the alumina layer are not conducive to further optimizing the passivation of the first surface. Only setting the first polysilicon layer on the second region is beneficial to optimizing the passivation effect of the second region; on the other hand, there is only one first polysilicon layer on the second region, which is beneficial to reducing the influence of parasitic absorption of light by polysilicon on the second region while achieving the optimization of the passivation effect of the second region to ensure a high light absorption utilization rate of the second region. Thereby, it is beneficial to improve the photoelectric conversion efficiency of the photovoltaic cell. In this way, the combined effect of multiple aspects is beneficial to improving the photoelectric conversion efficiency of the photovoltaic cell. Description of the Drawings

[0018] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplary illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the figures in the drawings do not constitute a scale limitation. To more clearly illustrate the technical solutions in the embodiments of the present disclosure or in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present disclosure. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 It is a schematic diagram of a partial cross-sectional structure of a photovoltaic cell provided by an embodiment of the present disclosure;

[0020] Figure 2 It is another schematic diagram of a partial cross-sectional structure of a photovoltaic cell provided by an embodiment of the present disclosure;

[0021] Figures 3 to 8 It is a schematic diagram of a partial cross-sectional structure corresponding to each step in the manufacturing method of a photovoltaic cell provided by another embodiment of the present disclosure. Detailed implementation manners

[0022] As can be seen from the background art, the photoelectric conversion efficiency of photovoltaic cells needs to be improved.

[0023] The present disclosure provides a photovoltaic cell and a manufacturing method thereof. In the photovoltaic cell, the ratio of the doping concentration of the doping element in the first polysilicon layer and the second polysilicon layer is designed to be 0.9 to 1.1, which is beneficial to reducing the resistivity of the entire passivation stack composed of the first polysilicon layer, the protective layer, and the second polysilicon layer located in the first region, thereby reducing the transport resistance of carriers in the passivation stack, so as to improve the collection efficiency of the photovoltaic cell for carriers. In addition, different from the first region where two polysilicon layers are provided, only one polysilicon layer is provided on the second region. On the one hand, it is beneficial to use the first polysilicon layer located on the entire first surface to passivate both the second region and the first region well, so as to reduce the density of defect states on the entire first surface. Compared with directly depositing an alumina layer on the second region for passivation, the fixed negative charges in the alumina layer are not conducive to further optimizing the passivation of the first surface. Only providing the first polysilicon layer on the second region is beneficial to optimizing the passivation effect of the second region; on the other hand, only one first polysilicon layer is provided on the second region, while achieving the optimization of the passivation effect of the second region, it is also beneficial to reduce the influence of the parasitic absorption of light by polysilicon on the second region, so as to ensure a high absorption utilization rate of light by the second region. Thereby, it is beneficial to improve the photoelectric conversion efficiency of the photovoltaic cell. In this way, the combined effect of multiple aspects is beneficial to improving the photoelectric conversion efficiency of the photovoltaic cell.

[0024] In the description of the embodiments of the present disclosure, technical terms such as "first" and "second" are only used to distinguish different objects, and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity, specific order, or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present disclosure, the meaning of "a plurality of" is more than two, unless otherwise specifically and clearly defined.

[0025] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in connection with the embodiments can be included in at least one embodiment of the present disclosure. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0026] In the description of the embodiments of the present disclosure, the term "and / or" is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: there is A, there is both A and B, and there is B. In addition, the character " / " in this document generally indicates that the associated objects before and after are in an "or" relationship.

[0027] In the description of the embodiments of the present disclosure, the term "a plurality of" means more than two (including two). Similarly, "a plurality of groups" means more than two groups (including two groups), and "a plurality of pieces" means more than two pieces (including two pieces).

[0028] In the description of the embodiments of the present disclosure, technical terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. This is only for the convenience of describing the embodiments of the present disclosure and simplifying the description, and does not indicate or imply that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation on the embodiments of the present disclosure.

[0029] In the description of the embodiments of the present disclosure, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and can be the communication inside 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 specific circumstances.

[0030] In the accompanying drawings corresponding to the embodiments of the present disclosure, for better understanding and convenience of description, the thickness and area of the layers are enlarged. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component can be "directly" on the surface of the other component, or there can be a third component between the two components. Conversely, 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 on a partial edge of the entire surface.

[0031] In the description of the embodiments of the present disclosure, when a certain component "includes" another component, unless otherwise specified, other components are not excluded, and other components may further be included. In addition, when components such as layers, films, regions, or plates are referred to as being "on / at" another component, it can be "directly on" the other component (i.e., on the surface of the other component with no other components therebetween), or there can be another component therebetween. In addition, when components such as layers, films, regions, plates are "directly located on" another component, or when components such as layers, films, regions, plates are located on the surface of another component, it means that no other components are located therebetween.

[0032] The terms used in the description of the various embodiments herein are only for describing specific embodiments and are not intended to be limiting. As used in the description of the various embodiments and the appended claims, "the component" is also intended to include the plural form, unless the context clearly indicates otherwise. Among them, the component includes components such as layers, films, regions, or plates.

[0033] The embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. However, those of ordinary skill in the art can understand that in the embodiments of the present disclosure, many technical details are provided to enable readers 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 required to be protected by the embodiments of the present disclosure can still be implemented.

[0034] An embodiment of the present disclosure provides a photovoltaic cell, and the photovoltaic cell provided by an embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0035] Reference Figure 1 or Figure 2, the photovoltaic cell includes: a substrate 100, the first surface 110 of the substrate 100 having a first region 120 and a second region 130 arranged alternately in a first direction X; a tunneling layer 101, located in the first region 120 and in the second region 130; a first polysilicon layer 102, located on the side of the tunneling layer 101 away from the substrate 100; a protective layer 103 on the first region 120, the protective layer 103 being located on the side of the first polysilicon layer 102 away from the substrate 100; a second polysilicon layer 104 on the first region 120, the second polysilicon layer 104 being located on the side of the protective layer 103 away from the first polysilicon layer 102; an electrode 106 on the first region 120, the electrode 106 being in electrical contact with the second polysilicon layer 104; wherein, the first polysilicon layer 102 and the second polysilicon layer 104 are doped with the same doping element, and the ratio of the doping concentration of the doping element in the first polysilicon layer 102 to that in the second polysilicon layer 104 is 0.9 to 1.1.

[0036] Wherein, Figure 1 is a schematic diagram of a partial cross-sectional structure of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 2 is another schematic diagram of a partial cross-sectional structure of a photovoltaic cell provided by an embodiment of the present disclosure.

[0037] It should be noted that the first polysilicon layer 102 can be regarded as including a contact portion 112 located in the first region 120 and a non-contact portion 122 located in the second region 130. The materials of the contact portion 112 and the non-contact portion 122 are the same. To clearly distinguish the contact portion 112 and the non-contact portion 122 in the first polysilicon layer 102, Figure 1 and Figure 2 different filling methods are used to draw the contact portion 112 and the non-contact portion 122 in both; in addition, the first direction X can be regarded as the length direction or the width direction of the photovoltaic cell, and the second direction Y can be regarded as the thickness direction of the photovoltaic cell.

[0038] It is worth noting that the doping concentrations of the doping element in the first polysilicon layer 102 and the second polysilicon layer 104 are similar, which is beneficial to reducing the overall resistivity of the passivation stack composed of the first polysilicon layer 102, the protective layer 103 and the second polysilicon layer 104 located in the first region 120, thereby reducing the transport resistance of carriers in the passivation stack, so as to improve the collection efficiency of the photovoltaic cell for carriers, and thus is beneficial to improving the photoelectric conversion efficiency of the photovoltaic cell.

[0039] In addition, only the first polysilicon layer 102 is designed to be located in the second region 130, while the second polysilicon layer 104 is only located in the first region 120. In other words, different from the first region 120 where two polysilicon layers (i.e., the first polysilicon layer 102 and the second polysilicon layer 104) are provided, only one polysilicon layer (i.e., the first polysilicon layer 102) is provided on the second region 130. On the one hand, it is beneficial to use the first polysilicon layer 102 located on the entire first surface 110 to passivate both the second region 130 and the first region 120 well, so as to reduce the density of defect states on the entire first surface 110. Compared with directly depositing an alumina layer on the second region 130 for passivation, the fixed negative charges in the alumina layer are not conducive to further optimizing the passivation of the first surface 110. Only setting the first polysilicon layer 102 on the second region 130 is beneficial to optimizing the passivation effect of the second region 130. On the other hand, only one first polysilicon layer 102 is provided on the second region 130. While achieving the optimization of the passivation effect of the second region 130, it is also beneficial to reduce the influence of the parasitic absorption of light by polysilicon on the second region 130, so as to ensure a high absorption utilization rate of light in the second region 130, thereby being beneficial to improving the photoelectric conversion efficiency of the photovoltaic cell.

[0040] In some cases, whether in the first polysilicon layer 102 or the second polysilicon layer 104, there may be slight differences in the doping concentration of the doping element in different regions of the film layer, but the doping concentration of the doping element in the entire film layer is stable within an average value range. Based on this, the ratio of the doping concentration of the doping element in the first polysilicon layer 102 to that in the second polysilicon layer 104 being 0.9 - 1.1 means that: the average doping concentration of the doping element in the first polysilicon layer 102 is the first doping concentration, the average doping concentration of the doping element in the second polysilicon layer 104 is the second doping concentration, and the ratio of the first doping concentration to the second doping concentration is 0.9 - 1.1. Among them, the average doping concentration of the doping element in the first polysilicon layer 102 is the average value of the doping concentrations of the doping element in different regions of the first polysilicon layer 102, and the average doping concentration of the doping element in the second polysilicon layer 104 is the average value of the doping concentrations of the doping element in different regions of the second polysilicon layer 104.

[0041] In some examples, on the premise that the ratio of the doping concentration of the doping element in the first polysilicon layer 102 to that in the second polysilicon layer 104 is 0.9 - 1.1, the average doping concentration of the doping element in the first polysilicon layer 102 can be 2×10 20 atom / cm 3 ~6×10 20 atom / cm 3 For example, it can be 2.5×10 20 atom / cm 3, 3×10 20 atom / cm 3 , 3.5×10 20 atom / cm 3 , 4×10 20 atom / cm 3 , 4.5×10 20 atom / cm 3 , 5×10 20 atom / cm 3 or 5.5×10 20 atom / cm 3 etc.; The average doping concentration of the doping element in the second polysilicon layer 104 can also be 2×10 20 atom / cm 3 ~6×10 20 atom / cm 3 , for example, it can be 2.5×10 20 atom / cm 3 , 3×10 20 atom / cm 3 , 3.5×10 20 atom / cm 3 , 4×10 20 atom / cm 3 , 4.5×10 20 atom / cm 3 , 5×10 20 atom / cm 3 or 5.5×10 20 atom / cm 3 etc.

[0042] A more detailed description of the photovoltaic cell provided by an embodiment of the present disclosure will be given below in conjunction with the accompanying drawings.

[0043] In some embodiments, refer to Figure 1 or Figure 2, along the first direction X, the electrode 106 with a partial thickness is embedded in the second polysilicon layer 104. In this way, by designing the doping concentrations of the doping elements in the first polysilicon layer 102 and the second polysilicon layer 104 to be similar, it is also beneficial to reduce the transfer resistance of the carriers in the substrate 100 to be sequentially transferred from the first polysilicon layer 102, the protective layer 103, and the second polysilicon layer 104 to the electrode 106, thereby improving the collection efficiency of the electrode 106 for the carriers; moreover, by designing the protective layer 103 between the contact portion 112 of the first polysilicon layer 102 and the second polysilicon layer 104, it is beneficial to block to a certain extent the diffusion of the material constituting the electrode towards the substrate, effectively reducing the high-density defect states caused by the direct contact between the material constituting the electrode and the substrate. In this way, the combined effect of multiple aspects is beneficial to improving the photoelectric conversion efficiency of the photovoltaic cell.

[0044] In some cases, the first polysilicon layer 102 is divided into a contact portion 112 located in the first region 120 and a non-contact portion 122 located in the second region 130. The contact portion 112 can be regarded as the part facing the electrode 106 along the second direction Y, and the non-contact portion 122 can be regarded as the region mainly used for receiving light in the first surface 110. It should be noted that the contact portion 112 facing the electrode 106 along the second direction Y includes the following two situations: the positive projection of the electrode on the first surface is located in the positive projection of the contact portion on the first surface, or the positive projections of the contact portion and the electrode on the first surface coincide.

[0045] In some cases, referring to Figure 1 or Figure 2 , the first region 120 at least includes the region where the positive projection of the electrode 106 on the substrate 100 is located, and the region on the first surface 110 other than the first region 120 is the second region 130. Among them, in order to ensure that the film layer contacted by the electrode has a relatively large doping concentration or the regions contacted by the electrode are all high-concentration regions, thereby reducing the contact resistance, generally, the positive projection area of the second region 130 is set to be greater than or equal to the positive projection area of the electrode. In other words, the positive projection area of the electrode on the substrate 100 is smaller than the area of the first region and the positive projection position must be within the first region. It should be noted that the number of the first regions 120 and the number of the second regions 130 can both be multiple, and the first regions 120 and the second regions 130 are alternately arranged along the first direction X. In other words, the first region 120 can be located in the interval between adjacent second regions 130, and the second region 130 can also be located in the interval between adjacent first regions 120.

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

[0047] In some embodiments, 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 in single crystal state, polycrystalline state, amorphous state or microcrystalline state (the state with both single crystal state and amorphous state is called microcrystalline state). For example, silicon may be at least one of monocrystalline 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 germanide, silicon carbide, gallium arsenide, indium gallium, perovskite, cadmium telluride, copper indium selenide and other materials. Subsequently, an exemplary description will be given with the material of the substrate 100 being silicon.

[0048] In some cases, the substrate 100 may be an N-type semiconductor substrate doped with an N-type doping element, and the first polysilicon layer 102 and the second polysilicon layer 104 are doped with the same doping element which is a P-type doping element. In some examples, the N-type doping element may be at least one of group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb) or arsenic (As); the P-type doping element may be at least one of group III elements such as boron (B), aluminum (Al), gallium (Ga) or indium (In).

[0049] In other cases, the substrate may also be a P-type semiconductor substrate doped with a P-type doping element, and the first polysilicon layer 102 and the second polysilicon layer 104 are doped with the same doping element which is an N-type doping element.

[0050] In some cases, the substrate 100 includes a front surface and a back surface that are opposite to each other in the second direction Y. In some examples, the photovoltaic cell is a single-sided cell, and the front surface can be regarded as the light-receiving surface of the photovoltaic cell for receiving incident light, and the first surface 110 can be used as the back surface, that is, the backlight surface. In other examples, the photovoltaic cell is a double-sided cell, then both the front surface and the back surface can be used as light-receiving surfaces and can be used to receive incident light, and the first surface 110 can be one of the front surface or the back surface. It can be understood that the backlight surface described in an embodiment of the present disclosure can also receive incident light, but the degree of receiving incident light is weaker than that of the light-receiving surface, so it is defined as the backlight surface. Subsequently, an exemplary description will be given with the first surface 110 being the backlight surface.

[0051] In some embodiments, referring to Figure 1 or Figure 2 , the protective layer 103 is also doped with the same doping element as that in the first polysilicon layer 102 and the second polysilicon layer 104, and the doping concentrations of the doping element in the second polysilicon layer 104, the protective layer 103 and the first polysilicon layer 102 decrease in sequence.

[0052] It should be noted that in the steps of preparing the first polysilicon layer 102 and the second polysilicon layer 104, the doping process can be carried out synchronously. Therefore, in the environment constructed by the doping process, some doping elements will sequentially diffuse into the protective layer 103 and the initial film layer used to form the first polysilicon layer 102. After the doping process is completed, some doping elements will remain in the protective layer 103, so that the protective layer 103 is also doped with the same doping elements as those in the first polysilicon layer 102 and the second polysilicon layer 104.

[0053] In addition, although the doping concentrations of the doping elements in the first polysilicon layer 102 and the second polysilicon layer 104 are similar, on this basis, it is designed that the doping concentration of the doping elements in the first polysilicon layer 102 is less than that in the second polysilicon layer 104, which is beneficial to making the resistivity of the second polysilicon layer 104 lower than that of the first polysilicon layer 102, so as to reduce the contact resistance between the electrode 106 and the second polysilicon layer 104 and improve the collection efficiency of the electrode 106 for carriers; moreover, compared with the second polysilicon layer 104, controlling the doping concentration of the doping elements in the first polysilicon layer 102 to be lower is beneficial to reducing the risk of the doping elements diffusing into the substrate 100, so as to reduce the recombination centers in the substrate 100, thereby reducing the probability of carriers recombining in the substrate 100, and thus increasing the carrier density transmitted to the electrode 106.

[0054] In some embodiments, referring to Figure 1 or Figure 2 , the material of the protective layer 103 includes at least one of metal nitride or metal oxide.

[0055] In some examples, the metal nitride includes aluminum nitride, titanium nitride, zirconium nitride, etc.; the metal oxide includes silicon oxide, titanium oxide, zirconium oxide, tantalum oxide, etc.

[0056] In some embodiments, referring to Figure 1 or Figure 2 , along the second direction Y, the second thickness of the protective layer 103 is less than the first thickness of the first polysilicon layer 102, and the first thickness of the first polysilicon layer 102 is less than or equal to the third thickness of the second polysilicon layer 104, and the second direction Y is the direction from the first polysilicon layer 102 to the second polysilicon layer 104.

[0057] Thus, designing a relatively large thickness for the second polysilicon layer 104 is beneficial for reducing the resistivity of the second polysilicon layer 104 itself, so as to ensure a good ohmic contact between the thickness of the second polysilicon layer 104 and the electrode 106; designing a relatively small thickness for the first polysilicon layer 102 is beneficial for enhancing the passivation effect of the passivation structure composed of the tunneling layer 101 and the first polysilicon layer 102 on the substrate 100. For example, enhancing the electric field strength formed by the first polysilicon layer 102 to improve the field passivation effect on the substrate 100. Moreover, it is beneficial for effectively reducing the influence of parasitic absorption of light by polysilicon caused by the first polysilicon layer 102 in the second region 130, so as to ensure a relatively high absorption utilization rate of light in the second region 130, thereby being beneficial for improving the photoelectric conversion efficiency of the photovoltaic cell. In addition, among the first polysilicon layer 102, the protective layer 103, and the second polysilicon layer 104, the second thickness of the protective layer 103 is the smallest, which is beneficial for enhancing the passivation effect of the passivation stack composed of the first polysilicon layer 102, the protective layer 103, and the second polysilicon layer 104 on the substrate 100, and reducing the contact resistance between the electrode 106 and the second polysilicon layer 104, while reducing the overall thickness of the passivation stack located in the first region 120 to reduce the overall thickness of the photovoltaic cell.

[0058] In some cases, referring to Figure 1 or Figure 2 , the ratio of the second thickness of the protective layer 103 to the first thickness of the first polysilicon layer 102 can be 0.007 to 0.075. For example, it can be 0.008, 0.009, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, 0.05, 0.055, 0.06, 0.065, or 0.07, etc.

[0059] In some examples, the second thickness of the protective layer 103 can be 0.5 nm to 1.5 nm. For example, it can be 0.6 nm, 0.7 nm, 0.8 nm, 1 nm, 1.1 nm, 1.2 nm, 1.3 nm, or 1.4 nm.

[0060] In some examples, the first thickness of the first polysilicon layer 102 can be 20 nm to 70 nm. For example, it can be 22 nm, 24 nm, 25 nm, 26 nm, 30 nm, 32 nm, 35 nm, 36 nm, 40 nm, 43 nm, 45 nm, 48 nm, 50 nm, 52 nm, 55 nm, 56 nm, 60 nm, 63 nm, 65 nm, or 68 nm, etc.

[0061] In some cases, referring to Figure 1 or Figure 2, the ratio of the first thickness of the first polysilicon layer 102 to the third thickness of the second polysilicon layer 104 can be 0.15 to 1. For example, it can be 0.16, 0.17, 0.18, 0.19, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, or 0.95, etc.

[0062] In some examples, the third thickness of the second polysilicon layer 104 can be 70 nm to 130 nm. For example, it can be 72 nm, 74 nm, 75 nm, 76 nm, 80 nm, 82 nm, 85 nm, 86 nm, 90 nm, 93 nm, 95 nm, 98 nm, 100 nm, 102 nm, 105 nm, 106 nm, 110 nm, 113 nm, 115 nm, 118 nm, 120 nm, 124 nm, 125 nm, 126 nm, or 128 nm, etc.

[0063] In some embodiments, referring to Figure 1 or Figure 2 , the material of the tunneling layer 101 can be silicon oxide.

[0064] In some embodiments, referring to Figure 1 or Figure 2 , along the second direction Y, the first thickness of the tunneling layer 101 can be 1.5 nm to 2.3 nm. For example, it can be 1.6 nm, 1.7 nm, 1.8 nm, 1.9 nm, 2.0 nm, or 2.1 nm, etc.

[0065] In some embodiments, referring to Figure 2 , the photovoltaic cell may further include: a first passivation layer 117, located on the side of the second polysilicon layer 104 away from the first surface 110. In some examples, the electrode 106 is embedded in the first passivation layer 117.

[0066] In some cases, the material of the first passivation layer 117 may include at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride.

[0067] In some examples, the first passivation layer 117 can be a single-layer structure. In other examples, the first passivation layer can be a stacked-layer structure. For a multi-layer structure, the materials of different layers can be different from each other, or the materials of some layers can be the same and different from the materials of other layers. It should be noted that Figure 2 the single-layer structure with the first passivation layer 117 being a silicon nitride layer is taken as an example.

[0068] In some embodiments, referring to Figure 2, the photovoltaic cell may further include: a second passivation layer 127, located on a side of the substrate away from the first surface 110 along the second direction Y.

[0069] In some cases, the material of the second passivation layer 127 may include at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride.

[0070] In some examples, the second passivation layer 127 may be a stacked structure. 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. In other examples, the passivation layer may also be a single-layer structure. It should be noted that Figure 2 the example is a stacked structure in which the second passivation layer 127 is an aluminum oxide layer and a silicon nitride layer, and the aluminum oxide layer is located between the substrate 100 and the silicon nitride layer.

[0071] In some embodiments, the photovoltaic cell may be any one of a PERC cell (Passivated Emitter Rear Cell), an IBC cell (Interdigitated Back Contact), a TOPCon cell (Tunnel Oxide Passivated Contact), a HIT / HJT cell (Heterojunction Technology), a thin-film solar cell, a stacked cell, etc., which have a passivation structure.

[0072] In summary, the doping concentrations of the doping elements in the first polysilicon layer 102 and the second polysilicon layer 104 are similar, which is beneficial to reducing the resistivity of the entire passivation stack located in the first region 120 and composed of the first polysilicon layer 102, the protective layer 103, and the second polysilicon layer 104. Thus, the transfer resistance of carriers in the passivation stack is reduced, so as to improve the collection efficiency of the photovoltaic cell for carriers, which is beneficial to improving the photoelectric conversion efficiency of the photovoltaic cell. In addition, different from the first region 120 where two polysilicon layers are provided (i.e., the first polysilicon layer 102 and the second polysilicon layer 104), only one polysilicon layer (i.e., the first polysilicon layer 102) is provided on the second region 130. On the one hand, it is beneficial to use the first polysilicon layer 102 located on the entire first surface 110 to passivate both the second region 130 and the first region 120 well, so as to reduce the density of defect states on the entire first surface 110. Compared with directly depositing an alumina layer on the second region 130 for passivation, the fixed negative charges in the alumina layer are not conducive to further optimizing the passivation of the first surface 110. Only providing the first polysilicon layer 102 on the second region 130 is beneficial to optimizing the passivation effect of the second region 130. On the other hand, only one first polysilicon layer 102 is provided on the second region 130. While achieving the optimization of the passivation effect of the second region 130, it is also beneficial to reduce the influence of parasitic absorption of light by polysilicon on the second region 130, so as to ensure a high absorption utilization rate of light by the second region 130, which is beneficial to improving the photoelectric conversion efficiency of the photovoltaic cell.

[0073] Another embodiment of the present disclosure further provides a manufacturing method of a photovoltaic cell for preparing the photovoltaic cell provided in the foregoing embodiment. The manufacturing method of the photovoltaic cell provided in another embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings. Figures 3 to 8 FIG. is a schematic partial cross-sectional structure diagram corresponding to each step in the manufacturing method of the photovoltaic cell provided in another embodiment of the present disclosure. It should be noted that the same or corresponding parts as those in the foregoing embodiment will not be described in detail here.

[0074] With reference to Figures 3 to 8 and Figure 1 and Figure 2 , the manufacturing method of the photovoltaic cell at least includes the following steps:

[0075] Step S1: With reference to Figure 3 , provide a substrate 100, and the first surface 110 of the substrate 100 has a first region 120 and a second region 130 arranged alternately along the first direction X. It should be noted that Figure 3 takes the surface opposite to the first surface 110 along the second direction Y as a matte surface to improve the light trapping effect as an example.

[0076] Step S2: With reference to Figure 4 , form a tunneling layer 101 on the first surface 110.

[0077] Step S3: Combining with reference Figures 4 to 6 , a first polysilicon film 132, a protective film 113, and a second polysilicon film 114 which are stacked are formed on a side of the tunneling layer 101 away from the substrate 100. The first polysilicon film 132 and the second polysilicon film 114 are doped with the same doping element, and a ratio of doping concentrations of the doping element in the first polysilicon film 132 and the second polysilicon film 114 is 0.9 to 1.1.

[0078] It should be noted that the first polysilicon film 132 is used to form a first polysilicon layer subsequently, and the second polysilicon film 114 is used to form a second polysilicon layer subsequently. In step S3, controlling the ratio of doping concentrations of the doping element in the first polysilicon film 132 and the second polysilicon film 114 to be 0.9 to 1.1 is beneficial to making the ratio of doping concentrations of the doping element in the first polysilicon layer and the second polysilicon layer also be 0.9 to 1.1 subsequently.

[0079] Step S4: Combining with reference Figures 4 to 8 , using the protective film 113 located in the second region 130 as an etch stop layer, performing a first etching process on the second polysilicon film 114 located in the second region 130, and exposing the protective film 113 located in the second region 130. The remaining second polysilicon film 114 located in the first region 120 serves as the second polysilicon layer 104.

[0080] It should be noted that the etching rate of the first etching process for the second polysilicon film 114 is much higher than that for the protective film 113. Therefore, in the step of etching the second polysilicon film 114 located in the second region 130 by using the first etching process, the protective film 113 located in the second region 130 can be used as an etch stop layer to accurately remove the second polysilicon film 114 located in the second region 130, which is beneficial to improving the etching accuracy of the first etching process.

[0081] Step S5: Referring to Figure 8 and Figure 1 , using the second polysilicon layer 104 located in the first region 120 as a mask, performing a second etching process on the exposed protective film 113 to remove the protective film 113 located in the second region 130. The remaining protective film 113 serves as the protective layer 103, and the exposed first polysilicon film 132 and the unexposed first polysilicon film 132 together serve as the first polysilicon layer 102.

[0082] In some cases, the first polysilicon film 132 located in the first region 120 can serve as a contact portion 112 of the first polysilicon layer 102, and the first polysilicon film 132 located in the second region 130 can serve as a non-contact portion 122 of the first polysilicon layer 102.

[0083] It should be noted that the etching rate of the second etching process on the protective film 113 is much higher than that on the second polysilicon layer 104. Therefore, without the need for an additional mask, the second polysilicon layer 104 can be used as a barrier layer to remove the protective film 113 located in the second region 130 and retain the first polysilicon film 132 located in the first region 120, which is beneficial to simplifying the manufacturing process of the photovoltaic cell.

[0084] In addition, compared with the complete removal of the polysilicon film layer in the second region 130 by using the laser film opening process, the combined action of the protective film 113, the first etching process, and the second etching process is beneficial to avoiding laser damage to the first surface 110 caused by the laser; moreover, retaining the first polysilicon film 132 in the second region 130 is beneficial to optimizing the passivation effect on the second region 130.

[0085] The following will detail each step in the manufacturing method of the photovoltaic cell provided by another embodiment of the present disclosure:

[0086] In some embodiments, referring to Figure 6 , in step S2, in the step of forming the stacked first polysilicon film 132, protective film 113, and second polysilicon film 114, an oxide layer 105 is further formed on the side of the second polysilicon film 114 away from the protective film 113.

[0087] It should be noted that in the step of forming the stacked first polysilicon film 132, protective film 113, and second polysilicon film 114, based on the function of the second polysilicon film 114 in the preparation process, the surface of a part of the thickness of the second polysilicon film 114 away from the substrate 100 is easily thermally oxidized, thereby forming an oxide layer 105 on the side of the second polysilicon film 114 away from the protective film 113.

[0088] Based on the above formation of the oxide layer 105, before the first etching process, the manufacturing method may further include: referring to Figure 6 and Figure 7 , selectively etching the oxide layer 105 to remove the oxide layer 105 located in the second region 130; referring to Figure 7 and Figure 8 , in the step of performing the first etching process, not only using the protective film 113 located in the second region 130 as an etching stop layer, but also using the remaining oxide layer 105 in the first region 120 as a mask to remove the second polysilicon film 114 located in the second region 130; in the subsequent step of performing the second etching process, referring to Figure 8 and Figure 1 , while removing the protective film 113 located in the second region 130, also removing the oxide layer 105 located in the first region 120.

[0089] It should be noted that not only is the etching rate of the first etching process on the second polysilicon film 114 much higher than that on the protective film 113, but also the etching rate of the first etching process on the second polysilicon film 114 is much higher than that on the oxide layer 105. Therefore, in the step of etching the second polysilicon film 114 located in the second region 130 by the first etching process, the protective film 113 located in the second region 130 can be used as an etching stop layer, and the remaining oxide layer 105 located in the first region 120 can be used as a mask. Thus, the second polysilicon film 114 located in the second region 130 can be accurately removed to improve the etching accuracy of the first etching process, while there is no need to additionally prepare a mask to protect the second polysilicon film 114 located in the first region 120 to form the second polysilicon layer 104 located in the first region 120, which is beneficial to further simplify the manufacturing process of the photovoltaic cell.

[0090] In one example, the materials of the first polysilicon film 132 and the second polysilicon film 114 can both be N-type polysilicon, and the material of the oxide layer 105 can be phosphosilicate glass.

[0091] In some embodiments, with reference to Figure 6 and Figure 7 The step of selectively etching the oxide layer 105 may include: using a laser to remove the oxide layer 105 located in the second region 130. It should be noted that since the second polysilicon film 114 located in the second region 130 will be removed in the subsequent step S4 of the first etching process, in the step of using a laser to remove the oxide layer 105 located in the second region 130, even if the laser causes certain laser damage to the second polysilicon film 114 located in the second region 130, it doesn't matter because the second polysilicon film 114 located in the second region 130 will also be removed subsequently, which will not affect the electrical performance of the finally formed photovoltaic cell. Moreover, using a laser to selectively remove the oxide layer 105 located in the second region 130 has a simple process and a high removal efficiency, which is beneficial to improving the manufacturing efficiency of the photovoltaic cell.

[0092] In some examples, in the step of using a laser to remove the oxide layer 105 located in the second region 130, the wavelength of the laser used can be 200μm - 300μm. For example, it can be 205μm, 210μm, 215μm, 220μm, 225μm, 230μm, 235μm, 240μm, 245μm, 250μm, 255μm, 260μm, 265μm, 270μm, 275μm, 280μm, 285μm, 290μm or 295μm.

[0093] In some embodiments, with reference to Figure 5 and Figure 6, the steps of forming the first polysilicon film 132, the protective film 113, and the second polysilicon film 114 in a stacked arrangement may include: Referring to Figure 5 , forming a first silicon material layer 142, an initial protective layer 123, and a second silicon material layer 124 in sequence on the side of the tunneling layer 101 away from the substrate 100; in combination with referring to Figure 5 and Figure 6 , doping the first silicon material layer 142, the initial protective layer 123, and the second silicon material layer 124 to form a first polysilicon film 132, a protective film 113, and a second polysilicon film 114 doped with the same element.

[0094] In some examples, the materials of the first silicon material layer 142 and the second silicon material layer 124 can both be polysilicon without doped doping elements. In the step of doping the first silicon material layer 142, the initial protective layer 123, and the second silicon material layer 124, it also promotes the crystallization of amorphous silicon to transform into polysilicon, so that the first silicon material layer 142 is transformed into a first polysilicon film 132 doped with doping elements, and the second silicon material layer 124 is transformed into a second polysilicon film 114 doped with doping elements; in other examples, the materials of the first silicon material layer and the second silicon material layer can also be polysilicon. In the step of doping treatment, it is only necessary to control the doping elements to diffuse into the second silicon material layer, the initial protective layer, and the first silicon material layer in sequence, and there is no need to realize the crystallization treatment of amorphous silicon.

[0095] It should be noted that in the step of doping the first silicon material layer 142, the initial protective layer 123, and the second silicon material layer 124, some doping elements will also remain in the initial protective layer 123, so that the finally formed protective layer 103 is also doped with doping elements.

[0096] In some cases, due to the influence of the distance of doping elements, the deeper the depth of diffusion of doping elements, the less the amount of doping elements that can diffuse to deeper depths, thus forming a phenomenon that the doping concentrations of doping elements in the second polysilicon layer 104, the protective layer 103, and the first polysilicon layer 102 decrease in sequence.

[0097] In some examples, the doping treatment of the first silicon material layer 142, the initial protective layer 123, and the second silicon material layer 124 may include the following steps: forming a doping source layer with doping elements on the side of the second silicon material layer 124 away from the initial protective layer 123 by using a deposition process; performing a high-temperature promotion treatment to further push the doping elements in the doping source layer into the second silicon material layer 124, the initial protective layer 123, and the first silicon material layer 142, and the doping source layer is transformed into an oxide layer 105.

[0098] In some cases, the doping element is phosphorus, and the doping source layer is a phosphorus-doped layer. The step of forming the doping source layer with the doping element includes: placing the semi-finished photovoltaic cell formed with the first silicon material layer 142, the initial protective layer 123, and the second silicon material layer 124 in a reaction chamber, providing first nitrogen and oxygen to the reaction chamber, and the first nitrogen is nitrogen flowing through liquid phosphorus trichloride (POCl3) or nitrogen carrying phosphorus trichloride, and controlling the temperature in the reaction chamber to be a first temperature to form a phosphorus-doped layer on the side of the second silicon material layer 124 away from the initial protective layer 123; on this basis, the step of performing high-temperature promotion treatment includes providing second nitrogen to the reaction chamber, and the second nitrogen can be regarded as pure nitrogen, and controlling the temperature in the reaction chamber to be a second temperature; wherein, the second temperature is greater than the first temperature to promote the diffusion of the doping element in the doping source layer into the second silicon material layer 124, the initial protective layer 123, and the first silicon material layer 142.

[0099] In some examples, the first temperature can be 780 °C to 830 °C. For example, it can be 785 °C, 790 °C, 795 °C, 800 °C, 805 °C, 810 °C, 815 °C, 820 °C, or 825 °C, etc.; the second temperature can be 880 °C to 930 °C. For example, it can be 885 °C, 890 °C, 895 °C, 900 °C, 905 °C, 910 °C, 915 °C, 920 °C, or 925 °C, etc.

[0100] In some examples, in the step of forming the doping source layer with the doping element, the flow rate of the first nitrogen provided can be 1000 sccm to 2000 sccm. For example, it can be 1100 sccm, 1200 sccm, 1300 sccm, 1400 sccm, 1500 sccm, 1600 sccm, 1700 sccm, 1800 sccm, or 1900 sccm, etc.; the flow rate of the oxygen provided can be 500 sccm to 1000 sccm. For example, it can be 550 sccm, 600 sccm, 650 sccm, 700 sccm, 750 sccm, 800 sccm, 850 sccm, 900 sccm, or 950 sccm, etc.

[0101] In some examples, in the step of performing high-temperature propulsion treatment, the flow rate of the second nitrogen gas provided can be 1000 sccm to 3000 sccm. For example, it can be 1100 sccm, 1200 sccm, 1300 sccm, 1400 sccm, 1500 sccm, 1600 sccm, 1700 sccm, 1800 sccm, 1900 sccm, 2000 sccm, 2100 sccm, 2200 sccm, 2300 sccm, 2400 sccm, 2500 sccm, 2600 sccm, 2700 sccm, 2800 sccm, or 2900 sccm, etc.

[0102] In some cases, in the step of forming a doped source layer with a doped element, the air pressure in the reaction chamber is controlled to be a first air pressure, and in the step of performing high-temperature propulsion treatment, the air pressure in the reaction chamber is controlled to be a second air pressure, and the second air pressure is greater than the first air pressure.

[0103] In some examples, the first air pressure can be 100 mbar to 200 mbar. For example, it can be 110 mbar, 120 mbar, 130 mbar, 140 mbar, 150 mbar, 160 mbar, 170 mbar, 180 mbar, or 190 mbar, etc.; the second air pressure can be 300 mbar to 500 mbar. For example, it can be 310 mbar, 320 mbar, 330 mbar, 340 mbar, 350 mbar, 360 mbar, 370 mbar, 380 mbar, 390 mbar, 400 mbar, 410 mbar, 420 mbar, 430 mbar, 440 mbar, 450 mbar, 460 mbar, 470 mbar, 480 mbar, or 490 mbar, etc.

[0104] In some examples, the duration of forming a doped source layer with a doped element can be 800 s to 1500 s. For example, it can be 850 s, 900 s, 950 s, 1000 s, 1050 s, 1100 s, 1150 s, 1200 s, 1250 s, 1300 s, 1350 s, 1400 s, or 1450 s, etc.

[0105] In some examples, the duration of performing high-temperature propulsion treatment can be 1000 s to 1600 s. For example, it can be 1050 s, 1100 s, 1150 s, 1200 s, 1250 s, 1300 s, 1350 s, 1400 s, 1450 s, 1500 s, or 1550 s, etc.

[0106] In some embodiments, refer to Figure 5, the step of forming the initial protective layer 123 may include: forming the initial protective layer 123 by a deposition process.

[0107] In some examples, the deposition process may be physical vapor deposition (PVD, Physical Vapor Deposition) or chemical vapor deposition (CVD, Chemical Vapor Deposition).

[0108] In some examples, the material of the initial protective layer 123 may include at least one of metal nitride or metal oxide.

[0109] In some embodiments, referring to Figure 2 , the manufacturing method of the photovoltaic cell may further include: forming a first passivation layer 117, and the first passivation layer 117 is located on the side of the second polysilicon layer 104 away from the first surface 110.

[0110] In some embodiments, referring to Figure 2 , the manufacturing method of the photovoltaic cell may further include: forming a second passivation layer 127, and the second passivation layer 127 is located on the side of the substrate away from the first surface 110 along the second direction Y.

[0111] In some embodiments, referring to Figure 1 or Figure 2 , the manufacturing method of the photovoltaic cell may further include: forming an electrode 106, the electrode 106 is at least located on the first surface 110, and the electrode 106 is embedded in the first passivation layer 117 and is in contact connection with the second polysilicon layer 104.

[0112] In some examples, the step of forming the electrode 106 may include: forming the electrode 106 by a screen printing process or an electroplating process.

[0113] In summary, in the manufacturing method provided by another embodiment of the present disclosure, on the one hand, during the process of etching the second polysilicon film 114 located in the second region 130 by the first etching process in step S4, the protective film 113 located in the second region 130 can be used as an etching stop layer to accurately remove the second polysilicon film 114 located in the second region 130, which is beneficial to improving the etching accuracy of the first etching process; on the other hand, in step S5, the etching rate of the second etching process for the protective film 113 is much higher than the etching rate for the second polysilicon layer 104. Therefore, without the need to additionally set a mask, the second polysilicon layer 104 can be used as a barrier layer to remove the protective film 113 located in the second region 130 and retain the first polysilicon film 132 located in the first region 120, which is beneficial to simplifying the manufacturing process of the photovoltaic cell. Moreover, retaining the first polysilicon film 132 located in the second region 130 is beneficial to optimizing the passivation effect on the second region 130.

[0114] Those of ordinary skill in the art can understand that the above embodiments are specific examples for implementing the present disclosure. In actual applications, various changes can be made to them in form and details 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. Therefore, the protection scope of the embodiments of the present disclosure should be subject to the scope defined by the claims.

Claims

1. A photovoltaic cell, characterized in that: include: A substrate, wherein a first surface of the substrate has first areas and second areas alternately arranged along a first direction; a tunneling layer located in the first region and in the second region; A first polysilicon layer, located on a side of the tunneling layer away from the substrate; a protective layer located on the first region, the protective layer being located on a side of the first polysilicon layer away from the substrate; a second polysilicon layer located on the first region, the second polysilicon layer being located on a side of the protective layer away from the first polysilicon layer; an electrode located on the first region, the electrode being in electrical contact with the second polysilicon layer; The first polysilicon layer and the second polysilicon layer are doped with the same doping element, and the ratio of the doping concentration of the doping element in the first polysilicon layer to the doping concentration of the second polysilicon layer is 0.9-1.

1.

2. The photovoltaic cell according to claim 1, characterized in that: The material of the protection layer includes at least one of metal nitride and metal oxide.

3. The photovoltaic cell according to claim 1, characterized in that: Along the second direction, the second thickness of the protective layer is less than the first thickness of the first polysilicon layer, the first thickness of the first polysilicon layer is less than or equal to the third thickness of the second polysilicon layer, and the second direction is the direction from the first polysilicon layer to the second polysilicon layer.

4. The photovoltaic cell according to claim 3, characterized in that: The ratio of the second thickness to the first thickness is 0.007-0.075; and / or the ratio of the first thickness to the third thickness is 0.15-1.

5. The photovoltaic cell according to claim 1, characterized in that: The protective layer is also doped with the doping element, and the doping concentrations of the doping element in the second polysilicon layer, the protective layer and the first polysilicon layer decrease in sequence.

6. A method for manufacturing a photovoltaic cell, characterized in that: include: Providing a substrate, wherein a first surface of the substrate has first areas and second areas alternately arranged along a first direction; forming a tunneling layer on the first surface; A first polysilicon film, a protective film, and a second polysilicon film are stacked and formed on a side of the tunneling layer away from the substrate, wherein the first polysilicon film and the second polysilicon film are doped with the same doping element, and a doping concentration ratio of the doping element in the first polysilicon film to the second polysilicon film is 0.9 to 1.1; Using the protective film located in the second area as an etching stop layer, performing a first etching process on the second polysilicon film located in the second area, exposing the protective film located in the second area, and leaving the second polysilicon film located in the first area as a second polysilicon layer; Using the second polysilicon layer as a mask, the exposed protective film is subjected to a second etching process to remove the protective film located in the second area, and the remaining protective film serves as a protective layer, and the exposed first polysilicon film and the unexposed first polysilicon film together serve as a first polysilicon layer.

7. The manufacturing method according to claim 6, characterized in that: In the step of forming the first polysilicon film, the protective film and the second polysilicon film in a stacked arrangement, an oxide layer is further formed on a side of the second polysilicon film away from the protective film; Before performing the first etching process, the manufacturing method further includes: selectively etching the oxide layer to remove the oxide layer located in the second region; In the step of performing the first etching process, not only the protection film located in the second region is used as an etching stop layer, but also the oxide layer remaining in the first region is used as a mask to remove the second polysilicon film located in the second region; In the step of performing the second etching process, the oxide layer located in the first region is also removed.

8. The manufacturing method according to claim 7, characterized in that: The step of selectively etching the oxide layer includes: removing the oxide layer located in the second area by using laser.

9. The manufacturing method according to claim 6 or 7, characterized in that: The step of forming the first polysilicon film, the protection film and the second polysilicon film in a stacked arrangement comprises: A first silicon material layer, an initial protective layer, and a second silicon material layer are sequentially formed on a side of the tunneling layer away from the substrate; the first silicon material layer, the initial protective layer, and the second silicon material layer are doped to form the first polysilicon film, the protective film, and the second polysilicon film doped with the same element.

10. The manufacturing method according to claim 9, characterized in that: The step of forming the initial protection layer may include: forming the initial protection layer by a deposition process.

Images