Solar cell and manufacturing method thereof

Abstract

The invention relates to a solar cell and a manufacturing method thereof, and the manufacturing method of the solar cell comprises the steps: providing a substrate which has a first conductive type; doping a doping element with a second conductive type in the surface layer of one side of the substrate to form an emitter, the second conductive type being opposite to the first conductive type; and texturing treatment is carried out on the surface of the emitting electrode, so that a first textured structure is formed on the surface of the emitting electrode. The efficiency of the solar cell can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of solar cell manufacturing, and in particular to a solar cell and a manufacturing method thereof. Background Art

[0002] With the continuous development of the photovoltaic industry, the demand for high-efficiency batteries is increasing, especially the demand for high-opening voltage cells. In the industrial production of high-efficiency batteries, selective emitter solar cells are widely used. The structural characteristics of selective emitter solar cells are that a high-doped deep expansion area is formed in the area where the emitter contacts the electrode, and a low-doped shallow expansion area is formed in the area where the emitter does not contact the electrode. By selectively doping different areas of the emitter, different diffusion effects are achieved in different areas of the emitter, thereby reducing the series resistance and improving the battery efficiency. At present, for selective emitter solar cells, how to further improve the selective emitter preparation process to further improve the photoelectric conversion efficiency of solar cells is of great significance. Summary of the invention

[0003] Based on this, it is necessary to provide a solar cell and a method for manufacturing the same in order to solve the problem of uneven emitter doping concentration of solar cells in the prior art.

[0004] In a first aspect, the present application provides a method for manufacturing a solar cell, comprising:

[0005] providing a substrate having a first conductivity type;

[0006] doping a doping element having a second conductivity type in a surface layer on one side of the substrate to form an emitter, wherein the second conductivity type is opposite to the first conductivity type;

[0007] A texturing process is performed on the surface of the emitter to form a first textured structure on the surface of the emitter.

[0008] In some embodiments, after the step of performing texturing on the surface of the emitter, the method further comprises:

[0009] forming a protective layer on the surface of the emitter;

[0010] A polishing process is performed on a surface of the substrate which is away from the emitter.

[0011] In some embodiments, the doping concentration of the second conductivity type doping element is 1×10 20 atom / cm 3 -9×10 21 atom / cm 3 .

[0012] In some embodiments, in the thickness direction of the substrate, the doping depth of the second conductivity type doping element is 1.5 micrometers to 2 micrometers.

[0013] In some embodiments, the first textured structure includes a plurality of pyramid structures, and the height of the pyramid structures in the thickness direction of the substrate is 0.5 micrometer to 1 micrometer.

[0014] In some embodiments, the step of doping a doping element having a second conductivity type in a surface layer on one side of the substrate comprises:

[0015] forming a doped oxide layer having a doping element of the second conductivity type on a surface of one side of the substrate;

[0016] In 900 o C-1200 o C, so that the doping element of the second conductivity type in the doped oxide layer diffuses into a surface layer on one side of the substrate;

[0017] The doped oxide layer is removed to form the emitter.

[0018] In some embodiments, the o C-1200 o In the step of performing the diffusion process under the temperature condition of C, the time of the diffusion process is 3h-4h.

[0019] In some embodiments, before the step of doping a doping element having a second conductivity type in a surface layer on one side of the substrate, the method further includes:

[0020] The substrate is cleaned and polished using an alkaline solution.

[0021] In some embodiments, after the step of performing texturing on the surface of the emitter, the method further comprises:

[0022] forming a first electrode on the first textured structure;

[0023] A second electrode is formed on a side of the substrate away from the first texture structure.

[0024] In a second aspect, the present application further provides a solar cell manufactured using any of the above-described methods for manufacturing a solar cell.

[0025] In the embodiment of the present application, the emitter is first formed by doping treatment, and then the surface of the emitter is subjected to a texturing treatment to form a first velvet structure on the surface of the emitter, which has many beneficial effects. 1) In the first aspect, the doping treatment is performed before the texturing treatment. Since the surface (first surface) of the substrate is a plane or substantially a plane, an emitter with uniform doping concentration can be obtained, and there will be no problem of uneven doping caused by texturing first and then doping, which improves the PN connection uniformity of the solar cell, thereby improving the photoelectric conversion efficiency of the solar cell. 2) In the second aspect, the texturing is performed after the doping treatment, so that the surface of the emitter away from the substrate has a first velvet structure, and there is no covering layer between the surface of the first velvet structure and the electrode. The first velvet structure can be in direct contact with the subsequent electrode, which can increase the contact area between the first velvet structure and the subsequent electrode, and improve the contact area and tightness between the first velvet structure and the subsequent electrode (it can prevent the electrode from falling off), and improve the efficiency of the solar cell and the reliability of the solar cell. 3) The emitter is directly doped on the substrate, and no additional film layer is required, which reduces the thickness of the solar cell and is conducive to the thinness of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments or exemplary embodiments of the present application, the drawings required for use in the description of the embodiments or exemplary embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A schematic diagram of the process steps of a method for manufacturing a solar cell provided in an embodiment of the present application.

[0028] Figure 2 A schematic diagram of a first intermediate process of a method for manufacturing a solar cell provided in an embodiment of the present application.

[0029] Figure 3 A schematic diagram of a second intermediate process of a method for manufacturing a solar cell provided in an embodiment of the present application.

[0030] Figure 4 A schematic diagram of a third intermediate process of a method for manufacturing a solar cell provided in an embodiment of the present application.

[0031] Figure 5 A schematic diagram of a solar cell provided in an embodiment of the present application.

[0032] Figure 6 A schematic diagram of the doping concentration of the emitter of a solar cell provided in an embodiment of the present application.

[0033] Figure 7 The figure is a schematic diagram of the doping concentration of the emitter of a solar cell in the prior art.

[0034] Reference numerals:

[0035] Solar cell 100; substrate 11; first surface 111; second surface 112; emitter 12; surface layer 11b; first velvet structure R1; first thickness d1; second thickness d2; first height h1; first electrode 14; front surface passivation layer 13; tunneling oxide layer 21; doped polysilicon layer 22; first passivation layer 24; second electrode 23. DETAILED DESCRIPTION

[0036] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0037] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0038] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0039] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0040] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0041] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0042] See also Figures 1 to 5 . Figure 1 A schematic diagram of the process steps of a method for manufacturing a solar cell provided in an embodiment of the present application. Figure 2 A schematic diagram of a first intermediate process of a method for manufacturing a solar cell provided in an embodiment of the present application. Figure 3 A schematic diagram of a second intermediate process of a method for manufacturing a solar cell provided in an embodiment of the present application. Figure 4 A schematic diagram of a third intermediate process of a method for manufacturing a solar cell provided in an embodiment of the present application.

[0043] Figure 5 A schematic diagram of a solar cell provided in an embodiment of the present application.

[0044] Figure 6 A schematic diagram of the doping concentration of the emitter of a solar cell provided in an embodiment of the present application. Figure 7The figure is a schematic diagram of the doping concentration of the emitter of a solar cell in the prior art.

[0045] In a first aspect, the present application provides a method for manufacturing a solar cell, such as Figure 1 As shown, the method for manufacturing a solar cell includes: step S100, step S200 and step S300.

[0046] Step S100 : providing a substrate, wherein the substrate has a first conductivity type.

[0047] For example, Figure 2 As shown, a substrate 11 is provided, and the substrate 11 has a first conductivity type.

[0048] For example, the substrate 11 may have a doping element, and the doping element type is N-type or P-type. The N-type element may be a V-group element such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As), and the P-type element may be a III-group element such as boron (B), aluminum (Al), gallium (Ga), or indium (In). For example, when the substrate 11 is a P-type substrate, the type of the doping element inside it is P-type. For another example, when the substrate 11 is an N-type substrate, the type of the doping element inside it is N-type.

[0049] For example, the substrate 11 has a first surface 111 and a second surface 112 that are arranged opposite to each other, one of the first surface 111 and the second surface 112 is the front side, and the other of the first surface 111 and the second surface 112 is the back side. In this application, the first surface 111 is the front side and the second surface 112 is the back side. The first surface 111 and the second surface 112 are arranged opposite to each other along the thickness direction (first direction Y) of the substrate 11. Both the first surface 111 and the second surface 112 can be used to receive incident light. In the embodiment of the present application, the first surface 111 of the substrate 11 is the main light-receiving surface, and the second surface 112 of the substrate 11 is the secondary light-receiving surface. It can be understood that the light-receiving surface and the backlight surface are relative, and the light-receiving surface is specifically the surface on the substrate 11 that is mainly irradiated by sunlight in the back contact solar cell or in the photovoltaic module. With the development of solar cell technology, the backlight surface will also receive energy from sunlight, mainly from reflected light or scattered light in the surrounding environment.

[0050] In step S200 , a doping element having a second conductivity type is doped into a surface layer on one side of the substrate to form an emitter, wherein the second conductivity type is opposite to the first conductivity type.

[0051] For example, Figure 3 As shown, a doping element having a second conductivity type is doped into a surface layer 11 b on one side of the substrate 11 to form an emitter 12 , where the second conductivity type is opposite to the first conductivity type.

[0052] For example, Figure 3 As shown, in the present application, the surface layer 11b including the first surface 111 is taken as an example for illustration.

[0053] For example, the first conductivity type and the second conductivity type are different, one of the first conductivity type and the second conductivity type is P-type conductivity, and the other of the first conductivity type and the second conductivity type is N-type conductivity.

[0054] For example, in some embodiments, the substrate 11 has a first conductivity type, the first conductivity type is P-type conductivity, and the substrate 11 has a group III doping element such as boron (B), aluminum (Al), gallium (Ga), or indium (In); the second conductivity type is N-type conductivity, and the emitter 12 has a group V doping element such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As).

[0055] For example, in some other embodiments, the substrate 11 has a first conductivity type, the first conductivity type is N-type conductivity, and the substrate 11 has a Group V doping element such as phosphorus (P), bismuth (Bi), antimony (Sb) or arsenic (As); the second conductivity type is P-type conductivity, and the emitter 12 has a Group III doping element such as boron (B), aluminum (Al), gallium (Ga) or indium (In).

[0056] For example, see Figure 2 and Figure 3 , the emitter 12 is a part of the substrate 11 .

[0057] It should be noted that, in some embodiments, the substrate 11 has a doping element of a first conductive type, and a doping element of a second conductive type is doped in a surface layer 11b on one side of the substrate 11 to form an emitter 12. At this time, the surface layer 11b or the emitter 12 also has a doping element of the first conductive type, and the concentration of the doping element of the second conductive type is greater than the concentration of the doping element of the first conductive type, so that the emitter 12 has the second conductive type.

[0058] Step S300: performing a texturing process on the surface of the emitter to form a first textured structure on the surface of the emitter.

[0059] For example, Figure 4 As shown, a texturing process is performed on the surface of the emitter 12 to form a first texture structure R1 on the surface of the emitter 12 .

[0060] For example, Figure 4As shown, the emitter 12 is a part of the substrate 11 , that is, a texturing process is performed on the first surface 111 of the substrate 11 to form a first textured structure R1 on the surface of the emitter 12 .

[0061] For example, in the prior art, a velvet structure is first obtained by a velvet treatment, and then a doping treatment is performed on the velvet structure to form an emitter. Since the velvet structure includes multiple uneven structures, such as multiple pyramid junction structures, when the doping process is performed, the velvet structure will cause uneven doping. Taking the thermal treatment of boron diffusion as an example, on the one hand, the high-temperature diffusion and the boron depletion effect of oxygen make the doping concentration always show a medium-high-low change trend from the outside to the inside. Such an energy band has a reverse bend, which is not conducive to the passivation of the step field effect; on the other hand, doping on the textured (uneven structure) surface exacerbates the concentration difference between the peaks and valleys, which is not conducive to improving the uniformity of the PN junction. That is, the prior art makes the PN junction uniformity of the solar cell poor, reducing the photoelectric conversion efficiency of the solar cell.

[0062] In the embodiment of the present application, the emitter 12 is first formed by the doping treatment of step S200, and then the surface of the emitter 12 is subjected to the texturing treatment in step S300, so that the first velvet structure R1 is formed on the surface of the emitter 12, which has many beneficial effects. 1) On the one hand, the doping treatment of step S200 is performed before the texturing treatment. Since the surface (first surface 111) of the substrate 11 is flat or substantially flat, an emitter with uniform doping concentration can be obtained, and there will be no problem of uneven doping caused by texturing first and then doping, which improves the PN connection uniformity of the solar cell, thereby improving the photoelectric conversion efficiency of the solar cell. 2) On the second aspect, after the doping treatment, the texture is made again, so that the surface of the emitter away from the substrate 11 has a first velvet structure R1, and there is no covering layer between the surface of the first velvet structure R1 and the electrode. The first velvet structure can directly contact the subsequent electrode, which can increase the contact area between the first velvet structure R1 and the subsequent electrode, and improve the contact area and tightness between the first velvet structure R1 and the subsequent electrode (which can prevent the electrode from falling off), thereby improving the efficiency of the solar cell and the reliability of the solar cell. 3) The emitter 12 is formed by direct doping on the substrate 11, without the need to add an additional film layer, which reduces the thickness of the solar cell and is conducive to the thinness of the solar cell.

[0063] It should be noted that, in some embodiments, the first conductivity type is N-type, and the second conductivity type is P-type.

[0064] For example, the first conductivity type is N-type, and the second conductivity type is P-type, that is, the substrate 11 is N-type conductive, and the emitter 12 is P-type conductive.

[0065] For example, the first conductivity type is N type, the second conductivity type is P type, the element doped in step S200 may be boron (B) element, and the emitter may be obtained through a boron diffusion process.

[0066] For example, the first conductivity type is N type, the second conductivity type is P type, and the doped element in step S200 is a III group element such as boron (B), aluminum (Al), gallium (Ga) or indium (In). Compared with N type doping, the mass or atomic size of the P type doped element is smaller, and the P type doped element has a smaller mass or atomic size in a direction perpendicular to the plane where the substrate 11 is located ( Figure 3 In the first direction Y), a thicker emitter 12 can be formed, and the P-type doped junction is deeper. In the subsequent texturing process in step S300, it is not easy to clean the emitter 12.

[0067] In some embodiments, after the step of performing texturing treatment on the surface of the emitter 12 (step S300 ), the step further includes: forming a protective layer on the surface of the emitter 12 ; and polishing the surface of the substrate 11 facing away from the emitter 12 .

[0068] By way of example, in some embodiments, after polishing the surface of the side of the substrate 11 away from the emitter 12, the process further includes: forming at least one of a tunneling oxide layer 21, a doped polysilicon layer 22 and a first passivation layer 24 on the side of the second surface 112 away from the substrate 11; and removing the protective layer on the surface of the emitter 12.

[0069] For example, Figure 5 The diagram shows a Tunnel Oxide Passivated Contact (TOPCon), where an emitter 12, a front surface passivation layer 13 and a first electrode 14 are stacked in sequence in a direction away from the substrate 11 on one side of the first surface 111, and the first electrode 14 is electrically connected to the emitter 12; a tunnel oxide layer 21, a doped polysilicon layer 22, a first passivation layer 24 and a second electrode 23 are stacked in sequence in a direction away from the substrate 11 on one side of the second surface 112, and the second electrode 23 is electrically connected to the doped polysilicon layer 22; the tunnel oxide layer 21 can allow majority electrons to tunnel into the doped polysilicon layer 22, while blocking the recombination of minority holes, so that electrons are laterally transmitted in the doped polysilicon layer 22 and collected by metal, which greatly reduces the recombination rate, improves the open circuit voltage and short circuit current of the battery, and thus improves the battery conversion efficiency. It should be noted that the structure of the oxide passivated contact battery (TOPCon) is not limited to Figure 5 Indicates.

[0070] For example, one of the first electrode 14 and the second electrode 23 is a positive electrode, and the other of the first electrode 14 and the second electrode 23 is a negative electrode.

[0071] For example, taking an oxide passivated contact cell (TOPCon) as an example, in an embodiment of the present application, the process of a method for manufacturing a solar cell includes: step S100, providing a substrate 11, the substrate 11 having a first conductivity type; step S200, doping an element having a second conductivity type in a surface layer 11b on one side of the substrate 11 to form an emitter 12, the second conductivity type being opposite to the conductivity type of the first conductivity type; step S300, performing a texturing treatment on the surface of the emitter 12 to form a first texturing structure R1 on the surface of the emitter 12; subsequent step 1, forming a protective layer on the surface of the emitter 12; subsequent step 2, polishing a side surface of the substrate 11 away from the emitter 12 (for example, cleaning and polishing treatment); subsequent step 3, forming at least one of a tunneling oxide layer 21, a doped polysilicon layer 22 and a first passivation layer 24 on the side of the second surface 112 away from the substrate 11; subsequent step 4, removing the protective layer on the surface of the emitter 12.

[0072] For example, in the process of manufacturing some solar cells, such as in the process of manufacturing oxide passivated contact cells (TOPCon), it is necessary to perform the above-mentioned subsequent step 1 to form a protective layer on the surface of the emitter 12. The material of the protective layer can be silicon oxide. The protective layer can protect the emitter 12 and prevent the emitter 12 from being damaged during the subsequent manufacturing process.

[0073] In some embodiments, the doping concentration of the second conductivity type doping element is 1×10 20 atom / cm 3 -9×10 21 atom / cm 3 .

[0074] For example, in step S200, the doping concentration of the second conductive type doping element is 1×10 20 atom / cm 3 -9×10 21 atom / cm 3 , an emitter 12 with excellent performance can be formed.

[0075] In some embodiments, in the thickness direction of the substrate 11 , the doping depth of the second conductivity type doping element is 1.5 micrometers to 2 micrometers.

[0076] For example, the doping concentration of the second conductivity type doping element is 1×10 20 atom / cm 3 -9×10 21 atom / cm 3The doping depth in the range of 1.5 microns to 2 microns can not only form an emitter 12 with excellent performance, but also form a textured structure with appropriate height in the subsequent step S300.

[0077] For example, compare Figure 6 and Figure 7 ,exist Figure 6 and Figure 7 In the figure, the horizontal axis represents the doping depth of the second conductivity type doping element (in micrometers), and the vertical axis represents the doping concentration (in atoms / cm 3 ), Figure 6 FIG. 4 illustrates the variation of the doping concentration of the second conductivity type doping element with the doping depth in the embodiment of the present application. Figure 7 FIG. 4 illustrates the variation of the doping concentration of the second conductivity type doping element with the doping depth in the prior art. Figure 6 and Figure 7 It can be seen that 1) compared with the existing technology, when the doping concentration is greater than 1×10 16 atom / cm 3 In the range of 1×10 16 atom / cm 3 Within the range of, the doping concentration in the embodiment of the present application changes more gently with the doping depth, that is, in the embodiment of the present application, as the doping depth increases, the change in doping concentration is smaller, indicating that the embodiment of the present application has better doping uniformity.

[0078] In some embodiments, the first textured structure R1 includes a plurality of pyramid structures, and the height of the pyramid structures in the thickness direction of the substrate 11 is 0.5 micrometers to 1 micrometer.

[0079] For example, Figure 2 As shown, the thickness of the substrate 11 is a first thickness d1; Figure 3 As shown, in step S200, an emitter 12 having a thickness of a second thickness d2 is formed; Figure 4 As shown, in step S300, the height of the formed pyramid structure in the thickness direction of the substrate 11 is a first height h1, and the first height h1 is 0.5 microns to 1 micron. For example, the first height h1 can be any value of 0.5 microns, 0.6 microns, 0.7 microns, 0.8 microns, 0.9 microns, and 1 micron.

[0080] Illustratively, the first height h1 is smaller than the second thickness d2 .

[0081] For example, the second thickness d2 is 1.5 micrometers to 2 micrometers. For example, the second thickness d2 can be any value among 1.5 micrometers, 1.6 micrometers, 1.7 micrometers, 1.8 micrometers, 1.9 micrometers, and 2 micrometers.

[0082] For example, since the doping process of step S200 is first performed and then the texturing process of step S300 is performed, a first textured structure R1 with uniform doping concentration in each part is formed. The first textured structure R1 includes a plurality of pyramid structures, and the concentration of the second conductive type doping element near the bottom of the pyramid is the same as or similar to the concentration of the second conductive type doping element near the top of the pyramid. For example, the difference between the concentration of the second conductive type doping element near the bottom of the pyramid and the concentration of the second conductive type doping element near the top of the pyramid is less than 10%.

[0083] For example, the first textured structure R1 includes a plurality of pyramid structures, which are part of the emitter 12 and also include doping elements of the second conductivity type.

[0084] For example, the first textured structure R1 includes a plurality of pyramid structures, and the pyramid structures may be regular pyramid structures or inverted pyramid structures.

[0085] In some embodiments, the step of doping a doping element having a second conductivity type in the surface layer 11b on one side of the substrate 11 (step S200) includes: step S210, forming a doped oxide layer having a doping element having a second conductivity type on a surface of one side of the substrate 11; step S220, at 900 o C-1200 o C, so that the second conductive type doping element in the doped oxide layer diffuses into the surface layer 11 b on one side of the substrate 11 ; step S230 , removing the doped oxide layer to form the emitter 12 .

[0086] For example, in step S200, step S210 may be performed first to form a doped oxide layer having a doping element of the second conductivity type on the first surface 111; and then step S220 may be performed to form a doped oxide layer having a doping element of the second conductivity type on the first surface 111; o C-1200 o C, so that the second conductive type of doping elements in the doped oxide layer diffuse into the surface layer 11b on one side of the substrate 11; then step S230 is performed to remove the doped oxide layer and retain the doped surface layer 11b of the substrate 11 to form the emitter 12.

[0087] For example, in step S210, the substrate 11 is placed in a diffusion furnace, and a gas containing a boron source, such as boron trichloride (BCl3) or boron tribromide (BBr3), is introduced. At the same time, nitrogen and oxygen are introduced as carrier gas and reaction gas. The boron source gas decomposes and reacts with oxygen to form a layer of borosilicate glass (BSG) on the surface of the substrate 11. The borosilicate glass is mainly composed of B2O3 and SiO2. In step S220, at a high temperature (900°C), the substrate 11 is heated to 400°C. o C-1200 o C) condition, the boron in the borosilicate glass is diffused into the substrate 11 at high temperature.

[0088] Illustratively, the doped oxide layer is borosilicate glass (BSG).

[0089] In some embodiments, at 900 o C-1200 o In the step of performing the diffusion process under the temperature condition of C (step S220), the time of the diffusion process is 3h-4h.

[0090] For example, the diffusion process in step S220 takes 3 hours to 4 hours, which can form an emitter 12 with a suitable thickness.

[0091] In some embodiments, before the step of doping the surface layer 11 b of one side of the substrate 11 with the doping element having the second conductivity type (step S200 ), the method further includes: step S120 , cleaning the substrate 11 , and polishing the substrate 11 using an alkaline solution.

[0092] For example, before step S200, step S120 is performed to clean the substrate 11 and polish the substrate 11 with an alkaline solution to form a first surface 111 of the substrate 11. The first surface 111 is a plane or a nearly plane surface, which is prepared for subsequent doping to form an emitter 12 with uniform concentration, thereby avoiding uneven doping concentration of the emitter 12 due to unevenness on the first surface 111.

[0093] In some embodiments, after performing the texturing process on the surface of the emitter 12 (step S300), the method further includes: step S400, forming a first electrode 14 on the first texture structure R1; step S500, forming a second electrode 23 on a side of the substrate 11 away from the first texture structure R1.

[0094] For example, Figure 5 As shown, a first electrode 14 can be formed on the first surface 111 by a screen printing process, and the first electrode is electrically connected to the emitter 12; a second electrode 23 can be formed on a side of the second surface 112 away from the first surface 111 by a screen printing process.

[0095] For example, taking an oxide passivated contact cell (TOPCon) as an example in detail, the process of the method for manufacturing a solar cell in an embodiment of the present application includes: step S100, providing a substrate 11, the substrate 11 having a first conductivity type; step S120, cleaning the substrate 11, and polishing the substrate 11 with an alkaline solution, for example, first cleaning the residual organic matter with a low concentration of potassium hydroxide and hydrogen peroxide, and then cleaning and polishing with a high concentration of potassium hydroxide; step S200, doping a doping element with a second conductivity type in a surface layer 11b on one side of the substrate 11 to form an emitter 12, the second conductivity type is opposite to the first conductivity type; step S300, performing a texturing treatment on the surface of the emitter 12 to make the emitter The first velvet structure R1 is formed on the surface of the emitter 12; step SS1, a protective layer is formed on the surface of the emitter 12, and the material of the protective layer can be silicon oxide; step SS2, the second surface 112 is cleaned (the protective layer on the second surface 112 is removed) and polished; step SS3, a tunneling oxide layer 21 and a doped polysilicon layer 22 are sequentially formed on the second surface 112, and a doping process (for example, phosphorus doping) is performed on the polysilicon layer; step SS4, the polysilicon wrapping and protective layer on the side of the first surface 111 away from the substrate 11 are removed; step SS5, a front surface passivation layer 13 is formed on the side of the first surface 111 away from the substrate 11; step SS6, a first passivation layer 24 is formed on the side of the second surface 112 away from the substrate. For example, the process of the manufacturing method of the oxide layer passivated contact cell (TOPCon) can also include: forming a first anti-reflection layer on the side of the first surface 111 away from the substrate 11; forming a second anti-reflection layer on the side of the second surface 112 away from the substrate 11.

[0096] By way of example, a process of manufacturing a solar cell in the prior art is described in detail by taking an oxide passivated contact cell (TOPCon), which includes: providing a substrate 11 having a first conductivity type; cleaning the substrate 11, and performing a texturing process on the first surface 111; forming an emitter on a side of the first surface 111 away from the substrate 11; removing the PSG (phosphosilicate glass layer) on a side of the second surface 112, and cleaning and polishing the second surface 112; step SS3, sequentially forming a tunneling oxide layer 21 and a doped polysilicon layer 22 on the second surface 112, and performing a doping process (for example, phosphorus doping) on ​​the polysilicon layer; step SS4, removing the polysilicon plating on a side of the first surface 111 away from the substrate 11; step SS5, forming a front surface passivation layer 13 on a side of the first surface 111 away from the substrate 11; step SS6, forming a first passivation layer 24 on a side of the second surface 112 away from the substrate.

[0097] For example, in the manufacturing process of the oxide passivated contact cell (TOPCon), the differences between the embodiments of the present application and the prior art include: 1) first performing step S200 to form the emitter 12; 2) then performing step S300, performing a texturing treatment to form a first texturing structure R1 on the surface of the emitter 12; 3) performing step SS1, forming a protective layer on the surface of the emitter 12 to protect the emitter 12 and prevent the emitter 12 from being damaged in subsequent processes.

[0098] For example, compared with the prior art process of first texturing and then forming the emitter, in the embodiment of the present application, in step S100, the thickness of the provided substrate 11 is thicker; in step S200, the doping depth of the second conductive type of doping element is deeper, and the doping depth is 1.5 microns to 2 microns; in step S300, during the texturing process, more alkaline oxidants can be added, and the content of the alkaline oxidants is 0.5%-3% of the total volume of the texturing agent. The alkaline oxidants can be hydrogen peroxide, sodium hypochlorite, potassium peroxide, sodium peroxide, etc., to increase the texturing reaction rate; in step S300, the first velvet structure R1 includes a plurality of pyramids structure, the pyramid structure includes a second conductive type of doping element; in step S200, doping is performed on the smooth first surface 111, and the smooth doped surface compensates for the doping difference of the peaks and valleys of the later texturing, thereby improving the uniformity of the PN junction (avoiding the prior art in which doping is performed on the textured surface, aggravating the doping concentration difference of the peaks and valleys, which is not conducive to improving the uniformity of the PN junction); in step SS1, a protective layer is first formed on the surface of the emitter 12, and then the surface of the side of the substrate 11 away from the emitter 12 is polished, and the protective layer can protect the emitter 12 and prevent the emitter 12 from being damaged during the subsequent manufacturing process.

[0099] For example, the manufacturing method of the solar cell of the present application or the oxide layer passivated contact cell (Tunnel Oxide Passivated Contact, TOPCon), but not limited to this, when combined with other processes, the manufacturing method of the solar cell of the present application can also manufacture other types of solar cells, which is not limited here.

[0100] In a second aspect, based on the same application concept, the present application provides a solar cell 100 , which is manufactured using any one of the above-mentioned manufacturing methods.

[0101] For example, Figure 5As shown, the solar cell 100 may be a Passivated Emitter Rear Cell (PERC) or a Tunnel Oxide Passivated Contact (TOPCon), but is not limited thereto and may also be other types of solar cells.

[0102] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0103] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A method for manufacturing a solar cell, characterized in that: include: providing a substrate having a first conductivity type; doping a doping element having a second conductivity type in a surface layer on one side of the substrate to form an emitter, wherein the second conductivity type is opposite to the first conductivity type; A texturing process is performed on the surface of the emitter to form a first textured structure on the surface of the emitter.

2. The method for manufacturing a solar cell according to claim 1, characterized in that: After the step of performing texturing on the surface of the emitter, the method further comprises: forming a protective layer on the surface of the emitter; A polishing process is performed on a surface of the substrate which is away from the emitter.

3. The method for manufacturing a solar cell according to claim 1, characterized in that: The doping concentration of the second conductive type doping element is 1×10 20 atom / cm 3 -9×10 21 atom / cm 3 .

4. The method for manufacturing a solar cell according to claim 1, characterized in that: In the thickness direction of the substrate, the doping depth of the second conductive type doping element is 1.5 micrometers to 2 micrometers.

5. The method for manufacturing a solar cell according to claim 1, characterized in that: The first textured structure includes a plurality of pyramid structures, and the height of the pyramid structures in the thickness direction of the substrate is 0.5 micrometer to 1 micrometer.

6. The method for manufacturing a solar cell according to claim 1, characterized in that: The step of doping a doping element having a second conductivity type in a surface layer on one side of the substrate comprises: forming a doped oxide layer having a doping element of the second conductivity type on a surface of one side of the substrate; In 900 o C-1200 o C, so that the doping element of the second conductivity type in the doped oxide layer diffuses into a surface layer on one side of the substrate; The doped oxide layer is removed to form the emitter.

7. The method for manufacturing a solar cell according to claim 6, characterized in that: In 900 o C-1200 o In the step of performing the diffusion process under the temperature condition of C, the time of the diffusion process is 3h-4h.

8. The method for manufacturing a solar cell according to claim 1, characterized in that: Before the step of doping a doping element having a second conductivity type in a surface layer on one side of the substrate, the method further includes: The substrate is cleaned and polished using an alkaline solution.

9. The method for manufacturing a solar cell according to claim 1, characterized in that: After the step of performing texturing on the surface of the emitter, the method further comprises: forming a first electrode on the first textured structure; A second electrode is formed on a side of the substrate away from the first texture structure.

10. A solar cell, characterized in that: The solar cell is manufactured by the method for manufacturing a solar cell according to any one of claims 1 to 9.

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