Solar cell and its manufacturing method

Abstract

The present disclosure relates to the field of photovoltaic technology, and provides a solar cell and a method for manufacturing the same. The method for manufacturing the solar cell includes: providing a substrate; sequentially forming a tunneling layer and a polysilicon layer on the substrate; performing a first doping process on the polysilicon layer on the second region to convert the polysilicon layer on the second region into a first polysilicon portion containing oxygen atoms and a second polysilicon portion not containing oxygen atoms; performing a second doping process on the polysilicon layer, the first polysilicon portion, and the second polysilicon portion on the second surface, so as to convert the polysilicon layer on the first region into a first doped polysilicon layer containing a doping element, and convert the second polysilicon portion into a second doped polysilicon layer containing a doping element, wherein the second doping process includes a heat treatment, and the heat treatment converts the first polysilicon portion containing oxygen atoms into a silicon oxide layer; removing the silicon oxide layer. The present disclosure can at least improve the manufacturing efficiency and reliability of the solar cell and the performance of the solar cell.

Description

Technical Field

[0001] The present disclosure relates to the field of photovoltaic technology, and particularly to a solar cell and a method for manufacturing the same. Background Art

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

[0003] Currently, the main types of solar cells include IBC cells (Interdigitated Back Contact cells), TOPCON (Tunnel Oxide Passivated Contact) cells, PERC cells (Passivated Emitter and Real Cell), and heterojunction cells, etc.

[0004] However, the reliability and efficiency of the current methods for manufacturing solar cells are relatively low. Summary of the Invention

[0005] Embodiments of the present disclosure provide a solar cell and a method for manufacturing the same, which can at least improve the manufacturing efficiency and reliability of the solar cell as well as the performance of the solar cell.

[0006] According to some embodiments of the present disclosure, on the one hand, a method for manufacturing a solar cell is provided, including: providing a substrate, the substrate including opposite first and second surfaces, the second surface including alternately arranged first and second regions; sequentially forming a tunneling layer and a polysilicon layer on the second surface; performing a first doping process on the polysilicon layer on the second region, so that the polysilicon layer on the second region is transformed into a first polysilicon portion containing oxygen atoms and a second polysilicon portion not containing oxygen atoms, the second polysilicon portion being located between the first polysilicon portion and the tunneling layer; performing a second doping process on the polysilicon layer, the first polysilicon portion, and the second polysilicon portion on the second surface, so that the polysilicon layer on the first region is converted into a first doped polysilicon layer containing a doping element, and the second polysilicon portion is converted into a second doped polysilicon layer containing the doping element, the second doping process including a heat treatment that converts the first polysilicon portion containing the oxygen atoms into a silicon oxide layer; removing the silicon oxide layer.

[0007] In some embodiments, the temperature of the heat treatment is 800 °C to 950 °C, and the duration of the heat treatment is 15 min to 25 min.

[0008] In some embodiments, the first doping process is ion implantation. The energy of the ion implantation is 10 keV to 50 keV, the duration of the ion implantation is 30 s to 90 s, the ion source of the ion implantation is an oxygen-containing gas, and the implantation dose of the ion source is 5×10 14 atoms / cm 2 ~5×10 15 atoms / cm 2 。

[0009] In some embodiments, the doping concentration of the doping element in the first doped polysilicon layer is the first doping concentration, the doping concentration of the doping element in the second doped polysilicon layer is the second doping concentration, and the ratio of the first doping concentration to the second doping concentration is 4 to 80.

[0010] In some embodiments, the first doping concentration is 2×10 19 atoms / cm 2 ~4×10 20 atoms / cm 2 ; the second doping concentration is 5×10 18 atoms / cm 2 ~5×10 19 atoms / cm 2 。

[0011] In some embodiments, performing the first doping process on the polysilicon layer on the second region includes: placing a mask plate on the second surface. The mask plate has a plurality of hollow portions penetrating through the mask plate, and the hollow portions correspond to the second regions on the substrate one by one; performing the first doping process on the polysilicon layer on the second region through the hollow portions; and removing the mask plate.

[0012] In some embodiments, the ratio of the thickness of the second doped polysilicon layer to the thickness of the first doped polysilicon layer is 0.43 to 0.92.

[0013] In some embodiments, the thickness of the second doped polysilicon layer is 10 nm to 90 nm, and the thickness of the first doped polysilicon layer is 120 nm to 160 nm.

[0014] In some embodiments, removing the silicon oxide layer includes: treating with a hydrofluoric acid solution having a concentration of 0.5% to 5% for a treatment duration of 30 s to 120 s and a treatment temperature of 20 °C to 25 °C.

[0015] According to some embodiments of the present disclosure, on the other hand, an embodiment of the present disclosure further provides a solar cell, including: a substrate, the substrate includes opposite first and second surfaces, and the second surface includes alternately arranged first and second regions; a tunneling layer, the tunneling layer is located on the second surface; a first doped polysilicon layer, the first doped polysilicon layer is located on the first region and on the surface of the tunneling layer facing away from the second surface; a second doped polysilicon layer, the second doped polysilicon layer is located on the second region and on the surface of the tunneling layer facing away from the second surface; wherein, both the first doped polysilicon layer and the second doped polysilicon layer contain doping elements, the doping concentration of the doping element in the second doped polysilicon layer is less than the doping concentration of the doping element in the first doped polysilicon layer, and the thickness of the second doped polysilicon layer is less than the thickness of the first doped polysilicon layer.

[0016] The technical solution provided by the embodiment of the present disclosure has at least the following advantages:

[0017] In the technical solution of the preparation method of the solar cell provided by the embodiment of the present disclosure, the preparation method of the solar cell includes providing a substrate, the substrate includes opposite first and second surfaces, and the second surface includes alternately arranged first and second regions; sequentially forming a tunneling layer and a polysilicon layer on the second surface; performing a first doping process on the polysilicon layer on the second region to convert the polysilicon layer on the second region into a first polysilicon part containing oxygen atoms and a second polysilicon part not containing oxygen atoms, and the second polysilicon part is located between the first polysilicon part and the tunneling layer; performing a second doping process on the polysilicon layer, the first polysilicon part and the second polysilicon part on the second surface to convert the polysilicon layer on the first region into a first doped polysilicon layer containing a doping element, and to convert the second polysilicon part into a second doped polysilicon layer containing a doping element, and the second doping process includes a heat treatment, and the heat treatment converts the first polysilicon part containing oxygen atoms into a silicon oxide layer; removing the silicon oxide layer.

[0018] First, through a first doping process, the polysilicon layer is transformed into a first polysilicon portion containing oxygen atoms and a second polysilicon portion not containing oxygen atoms, and the first polysilicon portion containing oxygen atoms is located on the surface of the second polysilicon portion facing away from the tunneling layer. Then, when performing the second doping process, the first polysilicon portion containing oxygen atoms is converted into a silicon oxide layer by the heat treatment of the second doping process, and the doping element introduced by the second doping process needs to pass through the silicon oxide layer to reach the second polysilicon portion. The silicon oxide layer will block part of the doping element from diffusing into the second polysilicon portion, resulting in a lower doping concentration of the doping element in the finally formed second doped polysilicon layer, thereby avoiding the problem of a relatively large recombination probability of carrier lateral flow caused by an excessive doping concentration of the doping element in the second doped polysilicon layer, and further improving the performance of the solar cell.

[0019] The polysilicon layer located on the second region is first transformed into a first polysilicon portion and a second polysilicon portion through a first doping process, and then into a silicon oxide layer and a second doped polysilicon layer through a second doping process, and the silicon oxide layer is finally removed. In other words, only a part of the thickness of the polysilicon layer is converted into the second doped polysilicon layer, so that the thickness of the second doped polysilicon layer can be relatively thin, thereby avoiding parasitic absorption caused by an excessive thickness of the second doped polysilicon layer, and further improving the performance of the solar cell.

[0020] In addition, in the above method for manufacturing a solar cell, a second doped polysilicon layer with a smaller thickness is formed through the first doping process and the second doping process, without using laser treatment in the related art. Therefore, the risk of damaging the substrate and the tunneling layer caused by laser treatment can be avoided, thereby improving the reliability of the method for manufacturing a solar cell.

[0021] In addition, compared with the method for manufacturing a second doped polysilicon layer with a lower doping concentration of doping elements by using a mask technology including multiple process steps in the related art, in the embodiment of the present disclosure, the second doped polysilicon layer with a lower doping concentration of doping elements is completed through the first doping process, the second doping process, and the removal of the silicon oxide layer. The process steps of the manufacturing method are fewer, which is beneficial to improving the manufacturing efficiency of the solar cell. Among them, by using the heat treatment in the second doping process, the first polysilicon portion containing oxygen atoms is converted into a silicon oxide layer that can block part of the doping element from diffusing, so that the first polysilicon portion can be converted into a silicon oxide layer without an additional heat treatment process after the first doping process, which is also beneficial to improving the manufacturing efficiency of the solar cell. Description of the Drawings

[0022] One or more embodiments are exemplarily illustrated by 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.

[0023] Figure 1 It is a schematic structural diagram of a solar cell in the related art;

[0024] Figure 2 It is a schematic structural diagram of providing a substrate in the method for preparing a solar cell provided by an embodiment of the present disclosure;

[0025] Figure 3 It is a schematic structural diagram after the first doping process in the method for preparing a solar cell provided by an embodiment of the present disclosure;

[0026] Figure 4 It is a schematic structural diagram after the second doping process in the method for preparing a solar cell provided by an embodiment of the present disclosure;

[0027] Figure 5 It is a schematic structural diagram after removing the silicon oxide layer in the method for preparing a solar cell provided by an embodiment of the present disclosure;

[0028] Figure 6 It is a schematic structural diagram after forming a passivation layer in the method for preparing a solar cell provided by an embodiment of the present disclosure.

[0029] Explanation of reference numerals:

[0030] 100, substrate; 110, front side; 120, back side; 130, first region; 140, second region; 101, tunneling oxide layer; 112, first doped polysilicon part; 122, second doped polysilicon part; 200, substrate; 210, first surface; 220, second surface; 230, first zone; 240, second zone; 201, emitter; 202, tunneling layer; 203, polysilicon layer; 213, first polysilicon part; 223, second polysilicon part; 204, first doped polysilicon layer; 205, second doped polysilicon layer; 206, silicon oxide layer; 207, passivation layer; 208, first antireflection layer; 218, second antireflection layer; 209, first electrode; 219, second electrode. Detailed implementation manners

[0031] Figure 1It is a schematic structural diagram of a solar cell in the related art.

[0032] Reference Figure 1 , the solar cell in the related art includes: a substrate 100, a tunneling oxide layer 101 and a doped polysilicon layer. The tunneling oxide layer 101 is located between the substrate 100 and the doped polysilicon layer, and the doped polysilicon layer has doping elements.

[0033] The substrate 100 has opposite front 110 and back 120. The back 120 includes alternately arranged first regions 130 and second regions 140. The doped polysilicon layer includes a first doped polysilicon part 112 and a second doped polysilicon part 122. The first doped polysilicon part 112 is located on the first region 130, and the second doped polysilicon part 122 is located on the second region 140. The first doped polysilicon part 112 located on the first region 130 is used for electrical contact with an electrode (not shown) to extract photo-generated carriers, and the second doped polysilicon part 122 located on the second region 140 is not in electrical contact with the electrode.

[0034] Among them, the thickness of the second doped polysilicon part 122 is relatively thick, resulting in serious parasitic absorption, which will affect the performance of the solar cell. And the concentration of the doping elements in the second doped polysilicon part 122 is relatively high, which will increase the recombination probability of carriers when flowing laterally in the doped polysilicon layer, making the open-circuit voltage of the solar cell relatively low, and thus the performance of the solar cell is relatively poor.

[0035] Therefore, in the preparation method of the solar cell in the related art, laser treatment is used to reduce the thickness of the second doped polysilicon part to reduce the parasitic absorption caused by the second doped polysilicon part. However, using laser treatment has a risk of causing laser damage to the tunneling oxide layer and the substrate, resulting in relatively low reliability of the solar cell in the related art.

[0036] In addition, in the preparation method of the solar cell in the related art, a mask technology is usually used to reduce the doping concentration of the second polysilicon part. Specifically, the preparation scheme includes: providing a substrate, the substrate has opposite front and back, the back includes alternately arranged first regions and second regions, and a tunneling layer and a polysilicon layer are provided on the back of the substrate; forming a first mask layer on the surface of the polysilicon layer facing away from the tunneling layer; then removing the first mask layer on the first region through techniques such as photolithography to form a first window; then performing high-concentration doping on the first window to convert the polysilicon layer on the first region into a first doped polysilicon part; removing the first mask layer; forming a second mask layer on the surfaces of the polysilicon layer and the first doped polysilicon part facing away from the tunneling layer; removing the second mask layer on the second region through photolithography technology to form a second window; then performing low-concentration doping on the second window to convert the polysilicon layer on the second region into a second doped polysilicon part; finally removing the second mask layer.

[0037] The above method has many process steps for reducing the doping concentration of the doping elements in the second polysilicon portion, resulting in a low preparation efficiency of the solar cell.

[0038] In the method for preparing a solar cell provided by an embodiment of the present disclosure, first, through a first doping process, a polysilicon layer is transformed into a first polysilicon portion containing oxygen atoms and a second polysilicon portion not containing oxygen atoms. Then, when performing a second doping process, the heat treatment of the second doping process is used to convert the first polysilicon portion containing oxygen atoms into a silicon oxide layer, and the doping elements introduced by the second doping process need to pass through the silicon oxide layer to reach the second polysilicon portion. The silicon oxide layer will block part of the doping elements from diffusing into the second polysilicon portion, so that the doping concentration of the doping elements in the finally formed second doped polysilicon layer is relatively low, thereby avoiding the problem of a large recombination probability of carrier lateral flow caused by an excessive doping concentration of the doping elements in the second doped polysilicon layer, and further improving the performance of the solar cell.

[0039] Part of the thickness of the polysilicon layer is converted into the final second doped polysilicon layer, so that the thickness of the second doped polysilicon layer can be relatively thin, thereby avoiding parasitic absorption caused by an excessive thickness of the second doped polysilicon layer, and further improving the performance of the solar cell.

[0040] In addition, in the above method for preparing a solar cell, a second doped polysilicon layer with a small thickness is formed through the first doping process and the second doping process, without using laser treatment in the related art. Therefore, the risk of damaging the substrate and the tunneling layer caused by laser treatment can be avoided, thereby improving the reliability of the method for preparing a solar cell.

[0041] In addition, compared with the method for preparing a second doped polysilicon layer with a relatively low doping concentration of doping elements by using a mask technology including multiple process steps in the related art, the embodiment of the present disclosure completes the preparation of a second doped polysilicon layer with a relatively low doping concentration of doping elements through three process steps: the first doping process, the second doping process, and removing the silicon oxide layer. The process steps of the preparation method are fewer, which is beneficial to improving the preparation efficiency of the solar cell. Among them, by using the heat treatment in the second doping process, the first polysilicon portion containing oxygen atoms is converted into a silicon oxide layer that can block part of the doping elements from diffusing, so that the first polysilicon portion can be converted into a silicon oxide layer without an additional heat treatment process after the first doping process, which is also beneficial to improving the preparation efficiency of the solar cell.

[0042] 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 understood 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 "plurality" is more than two, unless otherwise specifically defined.

[0043] Reference to "embodiment" in this text means that the specific features, structures, or characteristics described in connection with the embodiment may be included in at least one embodiment of the present disclosure. The phrase appearing in various positions in the specification 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 may be combined with other embodiments.

[0044] 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 three relationships may exist. For example, A and / or B may mean: A exists, both A and B exist, and B exists. In addition, the character " / " in this text generally represents an "or" relationship between the associated objects before and after.

[0045] In the description of the embodiments of the present disclosure, the term "plurality" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0046] 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. It is only for the convenience of describing the embodiments of the present disclosure and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the embodiments of the present disclosure.

[0047] 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 may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may 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.

[0048] 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, a film, a region, or a substrate) being on another component 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 being on the surface of another component or when the surface of a component forms or is provided with another component, it means that there is no third component between the two components. In addition, when describing a component being "substantially" formed on another component, it means that the component is not formed on the entire surface (or the front surface) of the other component, nor is it formed on a partial edge of the entire surface.

[0049] 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, etc. are "directly located on" another component, or when components such as layers, films, regions, plates, etc. are located on the surface of another component, it means that no other components are located therebetween.

[0050] The following will elaborate on each embodiment of the present disclosure in conjunction with 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 presented for the reader to better understand the present disclosure. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present disclosure can still be implemented.

[0051] Figures 2 to 6 It is a schematic structural diagram corresponding to each step in the preparation method of the solar cell provided for the embodiments of the present disclosure.

[0052] Reference Figure 2 , the preparation method of the solar cell includes: providing a substrate 200, the substrate 200 includes opposite first surface 210 and second surface 220, and the second surface 220 includes alternately arranged first region 230 and second region 240.

[0053] The substrate 200 is used to receive incident light and generate photo-generated carriers. In some embodiments, the substrate 200 can be a semiconductor substrate 200.

[0054] In some embodiments, the material of the substrate 200 may be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon or germanium. Among them, the elemental semiconductor material may be single-crystalline, polycrystalline, amorphous or microcrystalline (a state with both single-crystalline and amorphous states is called microcrystalline). For example, silicon may be at least one of single-crystalline silicon, polycrystalline silicon, amorphous silicon or microcrystalline silicon.

[0055] In some embodiments, the material of the substrate 200 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.

[0056] The substrate 200 may also be a sapphire substrate, a silicon-on-insulator substrate or a germanium-on-insulator substrate.

[0057] The substrate 200 may be an N-type semiconductor substrate or a P-type semiconductor substrate. The N-type semiconductor substrate is doped with an N-type doping element, and 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 semiconductor substrate is doped with a P-type element, and 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).

[0058] The substrate 200 has opposite first surface 210 and second surface 220. In some embodiments, the solar cell is a single-sided cell, then the first surface 210 of the substrate 200 may be used as the light-receiving surface for receiving incident light, and the second surface 220 is used as the backlight surface. In some embodiments, the solar cell is a double-sided cell, then both the first surface 210 and the second surface 220 of the substrate 200 may be used as the light-receiving surfaces and can be used to receive incident light. It can be understood that the backlight surface referred to in the embodiments 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.

[0059] In some embodiments, a texturing process may be performed on at least one of the first surface 210 or the second surface 220 of the substrate 200 to form a textured surface on at least one of the first surface 210 or the second surface 220 of the substrate 200. In this way, the absorption and utilization rate of incident light by the first surface 210 and the second surface 220 of the substrate 200 can be enhanced. In some embodiments, the textured surface may be a pyramid textured surface. As a common textured surface, the pyramid textured surface not only reduces the reflectivity of the surface of the substrate 200, but also forms a light trap, enhances the absorption effect of the substrate 200 on incident light, and improves the photoelectric conversion efficiency of the solar cell.

[0060] Specifically, if the solar cell is a single-sided cell, a textured surface can be formed on the light-receiving surface of the substrate 200. For example, it can be a pyramid-shaped textured surface, and the backlight surface of the substrate 200 can be a polished surface, that is, the backlight surface of the substrate 200 is flatter than the light-receiving surface. It should be noted that for a single-sided cell, a textured surface can also be formed on both the light-receiving surface and the backlight surface of the substrate.

[0061] If the solar cell is a double-sided cell, textured surfaces can be formed on both the light-receiving surface and the backlight surface of the substrate.

[0062] The first region 230 on the second surface 220 is used to set the first electrode.

[0063] It should be noted that the first region 230 and the second region 240 are artificially defined regions. The first region 230 refers to the region where the positive projection of the first electrode on the substrate 200 is located, and the second region 240 refers to the region on the second surface where the first electrode is not provided. Among them, in order to ensure that the film layer contacted by the first electrode has a relatively high doping concentration or the regions contacted by the first electrode 209 are all high-concentration regions, thereby reducing the contact resistance, generally, the area of the first region 230 is set to be greater than or equal to the area of the positive projection of the first electrode on the substrate 200. In other words, the area of the positive projection of the first electrode on the substrate 200 is smaller than the area of the first region 230, and the position of the positive projection of the first electrode on the substrate 200 is within the first region 230.

[0064] In some embodiments, an emitter 201 is formed on the first surface 210 of the substrate 200, and the emitter 201 is used for electrical contact with the second electrode formed subsequently.

[0065] Among them, the conductivity type of the doping element of the emitter 201 is opposite to the conductivity type of the doping element of the substrate 200.

[0066] In some embodiments, taking the doping element type of the substrate 200 as N-type as an example, the method of forming the emitter 201 may include: providing an initial substrate, performing a diffusion process on the initial substrate from the surface of the initial substrate, diffusing a P-type doping element from the surface of the initial substrate into a partial thickness of the initial substrate, so as to convert a part of the initial substrate diffused with the P-type doping element into the emitter 201. The remaining part of the initial substrate forms the substrate 200. In some embodiments, the diffusion process may be an ion implantation process or a high-temperature diffusion process.

[0067] Continue to refer to Figure 2 , the method for manufacturing a solar cell further includes: sequentially forming a tunneling layer 202 and a polysilicon layer 203 on the second surface 220.

[0068] The tunneling layer 202 chemically passivates the second surface 220 of the substrate 200, specifically: by saturating the dangling bonds on the second surface 220 of the substrate 200, reducing the density of defect states on the second surface 220 of the substrate 200, and reducing the recombination centers on the surface of the substrate 200 to reduce the carrier recombination rate. Additionally, the tunneling layer 202 allows majority carriers to tunnel through while blocking minority carrier recombination, thereby greatly reducing the metal contact recombination current and enhancing the open-circuit voltage and short-circuit current of the solar cell.

[0069] The material of the tunneling layer 202 can be silicon oxide, titanium oxide, silicon nitride, aluminum oxide, hafnium oxide, etc.

[0070] The method for forming the tunneling layer 202 can be a thermal oxidation process or a chemical vapor deposition method.

[0071] The polysilicon layer 203 is used to form the first doped polysilicon layer and the second doped polysilicon layer subsequently.

[0072] The method for forming the polysilicon layer 203 can be a chemical vapor deposition method.

[0073] With reference to Figure 2 and Figure 3 , the method for manufacturing the solar cell further includes: performing a first doping process on the polysilicon layer 203 on the second region 240, so that the polysilicon layer 203 on the second region 240 is transformed into a first polysilicon portion 213 containing oxygen atoms and a second polysilicon portion 223 not containing oxygen atoms, and the second polysilicon portion 223 is located between the first polysilicon portion 213 and the tunneling layer 202.

[0074] It can be understood that during the first doping process, oxygen atoms diffuse from the surface of the polysilicon layer 203 facing away from the tunneling layer 202 into the polysilicon layer 203, and a part of the thickness of the polysilicon layer 203 is transformed into the first polysilicon portion 213 containing oxygen atoms. The remaining part of the polysilicon layer 203 on the second region 240 except the first polysilicon portion 213 is the second polysilicon portion 223. Oxygen atoms do not diffuse into the second polysilicon portion 223, so the second polysilicon portion 223 does not contain oxygen atoms.

[0075] In some embodiments, performing the first doping process on the first polysilicon portion 213 includes depositing a mask layer (not shown) on the surface of the polysilicon layer 203 facing away from the tunneling layer 202, then forming a window corresponding to the second region 240 through laser treatment; performing the first doping process on the first polysilicon portion 213 on the second region 240 through the window; and finally etching away the mask layer.

[0076] In some embodiments, the first doping process for the polysilicon layer 203 on the second region 240 includes: placing a mask plate (not shown) on the second surface 220, the mask plate having a plurality of hollow portions penetrating through the mask plate, and the hollow portions corresponding to the second regions 240 on the substrate 200 one by one; performing the first doping process on the polysilicon layer 203 on the second region 240 through the hollow portions; and removing the mask plate. That is, the doping of oxygen atoms in the polysilicon layer 203 on the second region 240 is completed by using the hollow portions of the mask plate, and the polysilicon layer 203 on the first region 230 will not be doped with oxygen atoms under the protection of the mask plate. In addition, compared with the technical solution of first depositing a mask layer by a chemical method and then performing laser treatment to form a window corresponding to the second region to complete the doping process on the second region, using a mask plate with hollow portions to complete the doping process on the second region 240 can save process steps and avoid damage to the polysilicon layer 203 caused by laser treatment, thereby improving the preparation efficiency and reliability of the solar cell.

[0077] In some embodiments, the thickness of the mask plate is 2 mm to 8 mm, such as 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm or 8 mm, and the mask plate is a silicon nitride mask plate or a metal mask plate.

[0078] In some embodiments, the first doping process is an ion implantation method, the energy of the ion implantation method is 10 KeV to 50 KeV, such as 10 KeV, 20 KeV, 30 KeV, 40 KeV or 50 KeV, etc.; the duration of the ion implantation method is 30 s to 90 s, such as 30 s, 40 s, 50 s, 60 s, 70 s, 80 s or 90 s, etc.; the ion source of the ion implantation method is an oxygen-containing gas, such as O2 or O3, etc.; the implantation dose of the ion source can be 5×10 14 atoms / cm 2 ~5×10 15 atoms / cm 2 , for example, it can be 5×10 14 atoms / cm 2 , 7×10 14 atoms / cm 2 , 9×10 14 atoms / cm 2 , 1×10 15 atoms / cm 2 , 3×10 15 atoms / cm 2 or 5×10 15 atoms / cm 2When the relevant process parameters of the first doping process are within the above ranges, it can be ensured that oxygen atoms can be effectively incorporated into the polysilicon layer 203 on the second region 240 and transformed into the first polysilicon part 213 containing oxygen atoms, and the oxygen content in the first polysilicon part 213 is sufficient to enable the first polysilicon part 213 to be transformed into a silicon oxide layer that can block the diffusion of doping elements in the subsequent second doping process.

[0079] In some embodiments, the thickness of the first polysilicon part 213 is 70 nm to 110 nm, such as 70 nm, 80 nm, 90 nm, 100 nm or 110 nm, etc. The thickness of the first polysilicon part 213 is the thickness of the subsequently formed silicon oxide layer. When the thickness of the first polysilicon part 213 is within the above ranges, it can be ensured that there is a thick enough silicon oxide layer in the subsequent process to block the diffusion of doping elements to the second polysilicon part 223, so that the doping concentration of the doping elements in the second doped polysilicon layer 205 converted from the second polysilicon part 223 is relatively low.

[0080] Reference Figure 3 and Figure 4 Moreover, the method for manufacturing a solar cell further includes: performing a second doping process on the polysilicon layer 203, the first polysilicon part 213, and the second polysilicon part 223 on the second surface 220, so that the polysilicon layer 203 on the first region 230 is converted into a first doped polysilicon layer 204 containing doping elements, and the second polysilicon part 223 is converted into a second doped polysilicon layer 205 containing doping elements. The second doping process includes heat treatment, and the heat treatment converts the first polysilicon part 213 containing oxygen atoms into a silicon oxide layer 206.

[0081] Generally, after doping treatment by ion implantation, high-temperature annealing is required to repair the lattice damage caused by ion implantation. In the method for manufacturing a solar cell according to the embodiments of the present disclosure, after ion implantation, a second doping process including heat treatment is performed. During the heat treatment, not only can the doping of doping elements be completed, but also the first polysilicon part 213 containing oxygen can be converted into a silicon oxide layer 206, and the lattice damage caused by ion implantation can be repaired, so that no additional heat treatment process is required for the first polysilicon part 213 after the first doping process, thereby improving the manufacturing efficiency of the solar cell. In addition, since the silicon oxide layer 206 will eventually be removed, even if the heat treatment process cannot ensure complete repair of the lattice damage of the silicon oxide layer 206 caused by ion implantation, it will still not affect the performance of the finally manufactured solar cell.

[0082] In some embodiments, the second doping process is a high-temperature diffusion method. The second doping process completes the introduction of doping elements by providing high-temperature conditions, that is, through heat treatment, to form the first doped polysilicon layer 204 and the second doped polysilicon layer 205. Additionally, by using the high-temperature diffusion method, the first polysilicon portion 213 containing oxygen atoms can be converted into a silicon oxide layer 206 that can block the diffusion of doping elements through the heat treatment provided by the high-temperature diffusion method. This enables the first polysilicon portion 213 to be converted into the silicon oxide layer 206 without the need for an additional heat treatment process after the first doping process, thereby improving the preparation efficiency of the solar cell.

[0083] The high-temperature diffusion method further includes: providing a doping source containing doping elements, and the gas flow rate of the doping source is 1 L / min to 2 L / min, such as 1 L / min, 1.2 L / min, 1.4 L / min, 1.6 L / min, 1.8 L / min, or 2 L / min.

[0084] The doping source can be phosphorus oxychloride, boron tribromide, boron trichloride, etc.

[0085] It should be noted that providing the doping source and the heat treatment are carried out simultaneously, that is, in the high-temperature environment provided by the heat treatment, a doping source containing doping elements is provided to form the first doped polysilicon layer 204 and the second doped polysilicon layer 205.

[0086] In some embodiments, the temperature of the heat treatment is 800 °C to 950 °C, such as 800 °C, 820 °C, 850 °C, 880 °C, 900 °C, 920 °C, or 950 °C, etc.; the duration of the heat treatment is 15 min to 25 min, such as 15 min, 18 min, 20 min, 23 min, or 25 min, etc. When the temperature and duration of the heat treatment are within the above ranges, it can ensure that the oxygen-containing first polysilicon portion 213 is converted into a silicon oxide layer 206 that can block the diffusion of doping elements, while also enabling the doping elements to be effectively incorporated into the polysilicon layer 203 on the first region 230 to form a first doped polysilicon layer 204 with a relatively high doping concentration of doping elements, and incorporated into the second polysilicon portion 223 to form a second doped polysilicon layer 205 with a relatively low doping concentration of doping elements.

[0087] The doping element can be a doping element of the same type as the substrate 200. For example, if the doping element type of the substrate 200 is P-type, then the doping element type introduced by the second doping process can also be P-type; if the doping element type of the substrate 200 is N-type, then the doping element type introduced by the second doping process can also be N-type.

[0088] It should be noted that the silicon oxide layer 206 can block the diffusion of doping elements into the second polysilicon portion 223. The blocking effect of the silicon oxide layer 206 is to block the diffusion of some doping elements, but there will still be some doping elements passing through the silicon oxide layer 206 to reach the second polysilicon portion 223, so that the second doped polysilicon layer 205 formed by the conversion of the second polysilicon portion 223 contains doping elements, and the doping concentration of the doping elements is relatively low.

[0089] In some embodiments, the doping concentration of the doping elements in the first doped polysilicon layer 204 is the first doping concentration, the doping concentration of the doping elements in the second doped polysilicon layer 205 is the second doping concentration, and the ratio of the first doping concentration to the second doping concentration is 4 to 80, such as 4, 8, 10, 20, 30, 40, 50, 60, 70, or 80. When the ratio of the first doping concentration to the second doping concentration is within the above range, the first doping concentration is relatively high and the second doping concentration is relatively low, which can make the sheet resistance of the first doped polysilicon layer 204 less than that of the second doped polysilicon layer 205; and the first electrode 209 is in electrical contact with the first doped polysilicon layer 204, and the contact resistance between the first electrode 209 and the first doped polysilicon layer 204 can be relatively small, enabling a good ohmic contact to be formed, reducing the metal contact recombination between the first electrode 209 and the first doped polysilicon layer 204, and being beneficial to improving the carrier collection ability of the first electrode 209. In addition, the doping concentration of the doping elements in the second doped polysilicon layer 205 is relatively low, making the parasitic absorption ability of the second doped polysilicon layer 205 for incident light relatively weak, which can reduce the parasitic absorption of the incident light by the second doped polysilicon layer 205 and improve the absorption utilization rate of the substrate 200 for the incident light.

[0090] Wherein, the ratio of the first doping concentration to the second doping concentration refers to the ratio of the average doping concentration of the doping elements in the first doped polysilicon layer 204 to the average doping concentration of the doping elements in the second doped polysilicon layer 205.

[0091] In some embodiments, the first doping concentration is 2×10 19 atoms / cm 2 ~4×10 20 atoms / cm 2 ,such as 2×10 19 atoms / cm 2 、4×10 19 atoms / cm 2 、6×10 19 atoms / cm 2 、8×10 19 atoms / cm 2 or 1×10 20 atoms / cm 2; The second doping concentration is 5×10 18 atoms / cm 2 ~5×10 19 atoms / cm 2 , for example 5×10 18 atoms / cm 2 ,7×10 18 atoms / cm 2 ,9×10 18 atoms / cm 2 , 1×10 19 atoms / cm 2 , 3×10 19 atoms / cm 2 or 5×10 19 atoms / cm 2 wait.

[0092] In some embodiments, the ratio of the thickness of the second doped polysilicon layer 205 to the thickness of the first doped polysilicon layer 204 is 0.43-0.92, for example, 0.43, 0.5, 0.6, 0.7, 0.8, 0.9 or 0.92. The ratio of the thickness of the second doped polysilicon layer 205 to the thickness of the first doped polysilicon layer 204 is within the above range, so that the thickness of the second polysilicon layer 203 is small, which can reduce the parasitic absorption caused by the second polysilicon layer 203, thereby improving the performance of the solar cell.

[0093] In some embodiments, the thickness of the second doped polysilicon layer 205 is 10 nm to 90 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm or 90 nm, etc.; the thickness of the first doped polysilicon layer 204 is 120 nm to 160 nm, such as 120 nm, 125 nm, 130 nm, 135 nm, 140 nm, 145 nm or 150 nm, etc. When the thickness of the second doped polysilicon layer 205 is within the above range, the parasitic absorption problem caused by the excessive thickness of the second doped polysilicon layer 205 can be avoided, thereby improving the performance of the solar cell. In addition, the thickness of the first doped polysilicon layer 204 is within the above range, and the thickness of the first doped polysilicon layer 204 is relatively large, so that the square resistance of the first doped polysilicon layer 204 electrically contacting the first electrode 209 can be smaller, and the contact resistance between the first electrode 209 and the first doped polysilicon layer 204 can be smaller, so that a better ohmic contact can be formed, and the metal contact recombination between the first electrode 209 and the first doped polysilicon layer 204 is reduced, which is beneficial to improving the performance of the solar cell.

[0094] Combined with reference Figure 4 and Figure 5, the method for preparing a solar cell further includes: removing the silicon oxide layer 206.

[0095] In some embodiments, removing the silicon oxide layer 206 includes: treating with a hydrofluoric acid solution having a concentration of 0.5% - 5%, such as 0.5%, 1%, 2%, 3%, 4% or 5%, etc.; the treatment duration is 30s - 120s, such as 30s, 40s, 50s, 60s, 70s, 80s, 90s, 100s, 110s or 120s, etc.; the treatment temperature is 20°C - 25°C, such as 20°C, 21°C, 22°C, 23°C, 24°C or 25°C. When the relevant parameters of the process steps for removing the silicon oxide layer 206 are within the above ranges, it can ensure the effective removal of the silicon oxide layer 206 without residue, and basically does not damage the first doped polysilicon layer 204 and the second doped polysilicon layer 205.

[0096] Among them, the hydrofluoric acid can be buffered hydrofluoric acid. Buffered hydrofluoric acid is formed by mixing hydrofluoric acid (HF) and ammonium fluoride (NH4F), which can improve the etching uniformity and reduce the damage to the first doped polysilicon layer 204 and the second doped polysilicon layer 205.

[0097] In a specific example, in the buffered hydrofluoric acid, the volume ratio of hydrofluoric acid, ammonium fluoride and water can be: HF:NH4F:H20 = 1:6:10.

[0098] Reference Figure 5 and Figure 6 , in some embodiments, the method for preparing a solar cell may further include forming a passivation layer 207 on the first surface 210. The passivation layer 207 is located on the surface of the emitter 201 away from the first surface 210, and plays a good passivation role on the first surface 210 of the substrate 200, reducing the defect state density of the first surface 210 of the substrate 200 and preferably suppressing the carrier recombination of the first surface 210 of the substrate 200.

[0099] The material of the passivation layer 207 can be at least one of silicon oxide, aluminum oxide, silicon nitride or silicon oxynitride.

[0100] In some embodiments, the passivation layer 207 can be a single-layer structure. In some embodiments, the passivation layer 207 can also be a multi-layer structure. The materials of the layers in the multi-layer structure can be different from each other, or, the materials of some of the layers can be different from each other, and the materials of the remaining part of the layers can be the same. For example, the passivation layer 207 can be a multi-layer structure of a silicon nitride layer and an aluminum oxide layer.

[0101] The method for forming the passivation layer 207 can be atomic layer deposition.

[0102] Continue to refer to Figure 6, in some embodiments, the method for manufacturing a solar cell may further include: forming a first antireflection layer 208 on the surface of the passivation layer 207 facing away from the emitter 201, and forming a second antireflection layer 218 on the surfaces of the first doped polysilicon layer 204 and the second doped polysilicon layer 205 facing away from the tunneling layer 202.

[0103] The first antireflection layer 208 can achieve a good antireflection effect, reduce the reflection of incident light by the first surface 210, and improve the utilization rate of incident light by the substrate 200. In addition, the first antireflection layer 208 can also play a good passivation role on the first surface 210, reduce the density of defect states on the first surface 210 of the substrate 200, and preferably inhibit the carrier recombination on the first surface 210 of the substrate 200.

[0104] The material of the first antireflection layer 208 may include at least one of aluminum oxide, silicon nitride, or silicon oxynitride.

[0105] The method for forming the first antireflection layer 208 may be chemical vapor deposition.

[0106] The second antireflection layer 218 can achieve a good antireflection effect, reduce the reflection of incident light by the second surface 220, and improve the utilization rate of incident light by the substrate 200. In addition, the second antireflection layer 218 can also play a good passivation role on the second surface 220, reduce the density of defect states on the second surface 220 of the substrate 200, and preferably inhibit the carrier recombination on the second surface 220 of the substrate 200.

[0107] The material of the second antireflection layer 218 may include at least one of aluminum oxide, silicon nitride, or silicon oxynitride.

[0108] The method for forming the second antireflection layer 218 may be chemical vapor deposition.

[0109] Continue to refer to Figure 6 , in some embodiments, the method for manufacturing a solar cell further includes forming a first electrode 209 and a second electrode 219, the first electrode 209 being in electrical contact with the first doped polysilicon layer 204, and the second electrode 219 being in electrical contact with the emitter 201.

[0110] In some embodiments, the method for forming the first electrode 209 may include: printing a metal paste on the surface of the second antireflection layer 218 in the first region 230 using a screen printing process.

[0111] In some embodiments, the metal paste may include at least one of silver, aluminum, copper, tin, gold, lead, or nickel.

[0112] Perform a sintering process on the metal paste. In some embodiments, the metal paste contains materials with highly corrosive components such as glass. Thus, during the sintering process, the corrosive components will corrode the second antireflection layer 218 and part of the first doped polysilicon layer 204, causing the metal paste to penetrate into the second antireflection layer 218 and part of the first doped polysilicon layer 204, and forming a first electrode 209 that is in electrical contact with the first doped polysilicon layer 204.

[0113] In some embodiments, the method of forming the second electrode 219 may include: printing a metal paste on the surface of part of the first antireflection layer 208 using a screen printing process. In some embodiments, the metal paste may include at least one of silver, aluminum, copper, tin, gold, lead, or nickel.

[0114] Perform a sintering process on the metal paste. In some embodiments, the metal paste contains materials with highly corrosive components such as glass. Thus, during the sintering process, the corrosive components will corrode the first antireflection layer 208, the passivation layer 207, and part of the emitter 201, causing the metal paste to penetrate into the first antireflection layer 208, the passivation layer 207, and part of the emitter 201, and forming a second electrode 219 that is in electrical contact with the emitter 201.

[0115] In the above method for manufacturing a solar cell, the doping concentration of the doping element in the finally formed second doped polysilicon layer 205 is relatively low, thereby avoiding the problem of a relatively high recombination probability of carrier lateral flow caused by an overly large doping concentration of the doping element in the second doped polysilicon layer 205, and thus improving the performance of the solar cell. The thickness of the finally formed second doped polysilicon layer 205 can be relatively small, thereby avoiding parasitic absorption caused by an overly thick second doped polysilicon layer 205, and thus improving the performance of the solar cell.

[0116] In addition, in the above method for manufacturing a solar cell, a second doped polysilicon layer 205 with a relatively small thickness is formed through the first doping process and the second doping process, without using laser treatment in related technologies. Therefore, the risk of damaging the substrate 200 and the tunneling layer 202 caused by laser treatment can be avoided, thereby improving the reliability of the method for manufacturing a solar cell.

[0117] In addition, compared with the method for preparing the second doped polysilicon layer 205 with a relatively low doping concentration of doped elements by using a mask technology including multiple process steps in the related art, the embodiments of the present disclosure complete the preparation of the second doped polysilicon layer 205 with a relatively low doping concentration of doped elements through a first doping process, a second doping process, and the removal of the silicon oxide layer 206. The process steps of the preparation method are fewer, which is beneficial to improving the preparation efficiency of the solar cell. Among them, by using the heat treatment in the second doping process, the first polysilicon part 213 containing oxygen atoms is converted into the silicon oxide layer 206 that can block the diffusion of some doped elements, so that the first polysilicon part 213 can be converted into the silicon oxide layer 206 without an additional heat treatment process after the first doping process, which is also beneficial to improving the preparation efficiency of the solar cell.

[0118] Correspondingly, on the other hand, the embodiments of the present disclosure also provide a solar cell prepared by the method for preparing a solar cell according to any of the foregoing embodiments. It should be noted that for the same or corresponding parts as those in the foregoing embodiments, reference may be made to the corresponding descriptions in the foregoing embodiments, which will not be elaborated below.

[0119] Refer to Figure 5 or Figure 6 , the solar cell includes: a substrate 200, the substrate 200 includes opposite first and second surfaces 210 and 220, and the second surface 220 includes alternately arranged first and second regions 230 and 240; a tunneling layer 202, the tunneling layer 202 is located on the second surface 220; a first doped polysilicon layer 204, the first doped polysilicon layer 204 is located on the first region 230 and on the surface of the tunneling layer 202 facing away from the second surface 220; a second doped polysilicon layer 205, the second doped polysilicon layer 205 is located on the second region 240 and on the surface of the tunneling layer 202 facing away from the second surface 220; wherein, both the first doped polysilicon layer 204 and the second doped polysilicon layer 205 contain doped elements, the doping concentration of the doped elements in the second doped polysilicon layer 205 is less than that of the doped elements in the first doped polysilicon layer 204, and the thickness of the second doped polysilicon layer 205 is less than that of the first doped polysilicon layer 204.

[0120] In the solar cell provided by the embodiment of the present disclosure, the concentration of the doping element in the first doped polysilicon layer 204 is relatively high, which can make the sheet resistance of the first doped polysilicon layer 204 smaller than that of the second doped polysilicon layer 205; and the first electrode 209 is in electrical contact with the first doped polysilicon layer 204, and the contact resistance between the first electrode 209 and the first doped polysilicon layer 204 can be relatively small, capable of forming a good ohmic contact, reducing the metal contact recombination between the first electrode 209 and the first doped polysilicon layer 204, and being beneficial to improving the carrier collection ability of the first electrode 209. In addition, the doping concentration of the doping element in the second doped polysilicon layer 205 is relatively low, making the parasitic absorption ability of the second doped polysilicon layer 205 relatively weak, thereby improving the performance of the solar cell. The thickness of the first doped polysilicon layer 204 is relatively large, so that the sheet resistance of the first doped polysilicon layer 204 in electrical contact with the first electrode 209 can be relatively small, the contact resistance between the first electrode 209 and the first doped polysilicon layer 204 can be relatively small, capable of forming a good ohmic contact, reducing the metal contact recombination between the first electrode 209 and the first doped polysilicon layer 204, and also improving the performance of the solar cell.

[0121] Those of ordinary skill in the art can understand that the above embodiments are specific embodiments for implementing the present disclosure. In actual applications, various changes can be made in form and details without departing from the spirit and scope 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 present disclosure. Therefore, the protection scope of the present disclosure should be subject to the scope defined by the claims.

Claims

1. A method for preparing a solar cell, characterized in that, Comprising: Providing a substrate, the substrate including opposite first and second surfaces, the second surface including alternately arranged first and second regions; Successively forming a tunneling layer and a polysilicon layer on the second surface; Performing a first doping process on the polysilicon layer on the second region to convert the polysilicon layer on the second region into a first polysilicon portion containing oxygen atoms and a second polysilicon portion not containing oxygen atoms, the second polysilicon portion being located between the first polysilicon portion and the tunneling layer, wherein the first doping process is an ion implantation method; Performing a second doping process on the first polysilicon portion, the second polysilicon portion, and the polysilicon layer on the first region to convert the polysilicon layer on the first region into a first doped polysilicon layer containing a doping element and to convert the second polysilicon portion into a second doped polysilicon layer containing the doping element, the second doping process including a heat treatment that converts the first polysilicon portion containing the oxygen atoms into a silicon oxide layer; Removing the silicon oxide layer.

2. The manufacturing method of the solar cell according to claim 1, characterized in that, The temperature of the heat treatment is 800 °C to 950 °C, and the duration of the heat treatment is 15 min to 25 min.

3. The manufacturing method of the solar cell according to claim 1, characterized in that, The energy of the ion implantation method is 10 KeV to 50 KeV, the duration of the ion implantation method is 30 s to 90 s, the ion source of the ion implantation method is an oxygen-containing gas, and the implantation dose of the ion source is 5×10 14 atoms / cm 2 ~5×10 15 atoms / cm 2 .

4. The manufacturing method of the solar cell according to claim 1, characterized in that, The doping concentration of the doping element in the first doped polysilicon layer is a first doping concentration, the doping concentration of the doping element in the second doped polysilicon layer is a second doping concentration, and the ratio of the first doping concentration to the second doping concentration is 4 to 80.

5. The method for preparing a solar cell according to claim 4, wherein, The first doping concentration is 2×10 19 atoms / cm 2 ~4×10 20 atoms / cm 2 ; The second doping concentration is 5×10 18 atoms / cm 2 ~5×10 19 atoms / cm 2 .

6. The manufacturing method of the solar cell according to claim 1, characterized in that, Performing the first doping process on the polysilicon layer on the second region includes: Placing a mask on the second surface, the mask having a plurality of through-holes penetrating the mask, the through-holes corresponding one-to-one to the second regions on the substrate; Performing the first doping process on the polysilicon layer on the second region through the through-holes; Removing the mask.

7. The manufacturing method of the solar cell according to claim 1, characterized in that, The ratio of the thickness of the second doped polysilicon layer to the thickness of the first doped polysilicon layer is 0.43 to 0.

92.

8. The manufacturing method of the solar cell according to claim 7, characterized in that, The thickness of the second doped polysilicon layer is 10 nm to 90 nm, and the thickness of the first doped polysilicon layer is 120 nm to 160 nm.

9. The method for preparing a solar cell according to claim 1, wherein Removing the silicon oxide layer includes: Treating with a hydrofluoric acid solution having a concentration of 0.5% to 5% for a treatment duration of 30 s to 120 s and a treatment temperature of 20 °C to 25 °C.

10. A solar cell, characterized in that, The solar cell is prepared by the method for preparing a solar cell according to any one of claims 1 to 9, and the solar cell includes: A substrate, the substrate including opposite first and second surfaces, the second surface including alternately arranged first and second regions; A tunneling layer, the tunneling layer being located on the second surface; A first doped polysilicon layer, the first doped polysilicon layer being located on the first region and on the surface of the tunneling layer facing away from the second surface; A second doped polysilicon layer, the second doped polysilicon layer being located on the second region and on the surface of the tunneling layer facing away from the second surface; Among them, both the first doped polysilicon layer and the second doped polysilicon layer contain doping elements. The doping concentration of the doping elements in the second doped polysilicon layer is less than that in the first doped polysilicon layer, and the thickness of the second doped polysilicon layer is less than that of the first doped polysilicon layer.

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