Photovoltaic cell and manufacturing method thereof

Abstract

The embodiment of the invention relates to the photovoltaic field, and provides a photovoltaic cell and a manufacturing method thereof, and the manufacturing method comprises the steps: providing a substrate with a first surface and a second surface which are opposite to each other; at least performing doping treatment on the first surface to form a doped layer with a first doped element; performing first laser processing on a part of the doping layer to form an activation part, wherein the residual doping layer is a doping part; performing first etching treatment on the first surface by taking the residual doped layer as a dead layer so as to remove the activated part and form a first suede surface; forming a doped polycrystalline silicon layer with a second doping element and a silica glass layer at least on one side, far away from the doping part, of the substrate; performing second laser treatment on at least part of the silica glass layer to form a loose part; taking the residual silica glass layer as a protective layer, at least carrying out second etching treatment on the second surface to remove the loose part and the doped polycrystalline silicon layer opposite to the loose part, and forming a second textured surface; the laser types adopted by the first laser treatment and the second laser treatment are different, so that the manufacturing process is at least simplified.

Description

Technical Field

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

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

[0003] Current photovoltaic cells mainly include IBC cells (Interdigitated Back Contact), TOPCON (Tunnel Oxide Passivated Contact), PERC cells (Passivated emitter and real cell) and heterojunction cells.

[0004] However, photovoltaic cells formed by different manufacturing methods have different photoelectric conversion efficiencies, and it is necessary to develop a manufacturing method that is more conducive to improving the photoelectric conversion efficiency of photovoltaic cells or simplifying the preparation process. Summary of the invention

[0005] The embodiments of the present disclosure provide a photovoltaic cell and a method for manufacturing the same, which are at least helpful in simplifying the manufacturing process of the photovoltaic cell and improving the photoelectric conversion efficiency of the photovoltaic cell.

[0006] According to some embodiments of the present disclosure, on the one hand, an embodiment of the present disclosure provides a method for manufacturing a photovoltaic cell, comprising: providing a substrate, the substrate having a first surface and a second surface relative to each other; performing a doping treatment on at least the first surface to form a doping layer having a first doping element; performing a first laser treatment on part of the doping layer to form an activation portion, and the remaining doping layer serves as a doping portion, wherein the doping concentration of the first doping element in the activation portion is lower than the doping concentration in the doping portion; taking the doping portion as a dead layer, performing a first etching treatment on the first surface to remove the activation portion and form a first velvet surface; sequentially forming a doped polysilicon layer and a silicon glass layer having a second doping element on at least one side of the substrate away from the doping portion; performing a second laser treatment on at least part of the silicon glass layer to form a loose portion; taking the remaining silicon glass layer as a protective layer, performing a second etching treatment on at least the second surface to remove the loose portion and the doped polysilicon layer opposite to the loose portion, and form a second velvet surface; wherein the first doping element and the second doping element are of different types, and the first laser treatment and the second laser treatment use different types of lasers.

[0007] In some embodiments, both the first surface and the second surface are third velvet surfaces; after forming the first velvet surface and before forming the doped polysilicon layer, it also includes: polishing the second surface to form a polished surface; the steps of forming the doped polysilicon layer and the silicon glass layer include: forming the doped polysilicon layer on the polished surface, and forming the silicon glass layer on the side of the doped polysilicon layer away from the polishing surface.

[0008] In some embodiments, after forming the first velvet surface and before forming the polishing surface, it also includes: at least oxidizing the first surface to form a first resistance expansion layer on the doped portion, and forming a second resistance expansion layer on the first velvet surface; the step of forming the doped polysilicon layer and the silicon glass layer also includes: forming the doped polysilicon layer on both the first resistance expansion layer and the second resistance expansion layer, and forming the silicon glass layer on the side of the doped polysilicon layer away from the first resistance expansion layer and the second resistance expansion layer.

[0009] In some embodiments, after forming the first velvet surface and before forming the polishing surface, the step further includes: performing an oxidation treatment on at least the first surface to form a first resistance diffusion layer on the doped portion, and forming a second resistance diffusion layer on the first velvet surface; the surface jointly formed by the first resistance diffusion layer and the second resistance diffusion layer includes an edge area and a central area surrounded by the edge area, and the step of forming the doped polysilicon layer and the silicon glass layer also includes: forming the doped polysilicon layer on the edge area, and forming the silicon glass layer on a side of the doped polysilicon layer away from the edge area.

[0010] In some embodiments, the first surface includes a first laser area and a first non-laser area alternately arranged along a first direction, and the second surface includes a second laser area and a second non-laser area alternately arranged along the first direction; the step of performing the first laser treatment on part of the doped layer includes: performing the first laser treatment on the doped layer located in the first laser area to form the activated portion located in the first laser area; the step of performing the second laser treatment on at least part of the silicon glass layer includes: performing the second laser treatment on the silicon glass layer located in the second laser area to form the loose portion located in the second laser area.

[0011] In some embodiments, an orthographic projection area of ​​the first laser zone on the substrate is different from an orthographic projection area of ​​the second laser zone on the substrate, and / or an orthographic projection of the first laser zone on the substrate at least partially overlaps or does not overlap with an orthographic projection of the second laser zone on the substrate.

[0012] In some embodiments, the step of performing the second etching treatment on at least the second surface includes: etching the first surface using a second chain hydrofluoric acid process to remove the silicon glass layer located on the first surface; etching the first surface and the second surface using a second texturing process to remove the doped polysilicon layer, the first resistance diffusion layer and the second resistance diffusion layer located on the first surface to expose the first texture surface and the doped portion, and removing the loose portion and the doped polysilicon layer located in the second laser zone to form the second texture surface.

[0013] In some embodiments, after performing the second texturing process, it also includes: using an acid pickling process to clean the second surface to remove the silicon glass layer located in the second non-laser area to expose the doped polysilicon layer located in the second non-laser area.

[0014] In some embodiments, the step of performing the first etching treatment on the first surface includes: etching the first surface using a first texturing process to remove the activated portion and form the first texturing surface.

[0015] In some embodiments, in the step of performing the first laser processing, an oxide layer is formed on the doping layer; in the step of performing the first etching processing on the first surface, before etching the first surface using the first texturing process, it also includes etching the first surface using a first chain hydrofluoric acid process to remove the oxide layer.

[0016] In some embodiments, the first laser treatment uses red nano laser, green nano laser or purple nano laser, and the second laser treatment uses purple laser, green laser, green flying laser or purple flying laser.

[0017] According to some embodiments of the present disclosure, on the other hand, embodiments of the present disclosure further provide a photovoltaic cell, comprising: a photovoltaic cell formed according to any of the manufacturing methods described above.

[0018] The technical solution provided by the embodiments of the present disclosure has at least the following advantages: On the one hand, the first laser treatment is used to activate part of the doped layer, so that the doping concentration of the first doping element in the part of the doped layer is reduced, and the order of the lattice in the part of the doped layer is improved, so that the part of the doped layer is converted into an activated part, and the remaining doped layer is used as a doped part. In other words, compared with the doped part, the doping concentration of the doping element in the activated part is lower, so that the overall order of the lattice in the activated part is stronger, and therefore, under the same etching conditions, the doped part is easier to be etched. On this basis, when the first surface is subsequently subjected to the first etching treatment, the etching rate of the first etching treatment on the activated part with a lower doping concentration of the first doping element is much higher than that of the doped part, so that the activation part can be removed and the first velvet surface can be formed with the doped part as a dead layer without the need for an additional mask, which is conducive to simplifying the manufacturing process of the photovoltaic cell. In addition, compared with the use of a laser film opening process to remove part of the doped layer to form a selective emitter structure in which only a part of the first surface retains the doped layer, the combined effect of the first laser treatment and the first etching treatment is conducive to reducing the laser damage to the first surface, thereby helping to reduce the surface defect state density of the first surface, so as to improve the photoelectric conversion efficiency of the photovoltaic cell finally formed. Moreover, forming a selective emitter structure in which only a part of the first surface has a doped layer, that is, a doped portion, is conducive to reducing the contact resistance between the subsequently formed electrode and the doped portion, and reducing the probability of carrier recombination in other areas of the first surface.

[0019] On the other hand, the second laser treatment is used to modify part of the silicon glass layer into a loose part, so that the looseness and porosity of the loose part is higher than the looseness and porosity of the remaining silicon glass layer. On this basis, when the second etching treatment is subsequently performed on at least the second surface, the etching rate of the second etching treatment on the loose part with a higher degree of porosity is much higher than that of the remaining silicon glass layer, so that the loose part and the doped polysilicon layer opposite to the loose part can be removed without setting an additional mask, and the second velvet surface can be formed by using the remaining silicon glass layer as a protective layer, which is conducive to simplifying the manufacturing process of photovoltaic cells. Moreover, removing the doped polysilicon layer opposite to the loose part is conducive to avoiding the parasitic absorption of light by the doped polysilicon layer that is removed. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings, and these exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise specified, the pictures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the traditional technology, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A schematic diagram of a partial cross-sectional structure of a substrate provided in a method for manufacturing a photovoltaic cell according to an embodiment of the present disclosure; Figure 2 A schematic diagram of a partial cross-sectional structure formed after at least a first surface is doped in a method for manufacturing a photovoltaic cell according to an embodiment of the present disclosure; Figure 3 A schematic diagram of a local cross-sectional structure formed after a first laser treatment in a method for manufacturing a photovoltaic cell according to an embodiment of the present disclosure is provided; Figure 4 A schematic diagram of a partial cross-sectional structure formed after a first etching process is performed in a method for manufacturing a photovoltaic cell according to an embodiment of the present disclosure; Figure 5 A schematic diagram of a partial cross-sectional structure formed after at least a first surface is oxidized in a method for manufacturing a photovoltaic cell according to an embodiment of the present disclosure; Figure 6 For Figure 5 A schematic diagram of a partial cross-sectional structure formed by polishing the second surface based on the structure shown; Figure 7 For Figure 6 A schematic diagram of a local cross-sectional structure in which a doped polysilicon layer and a silicon glass layer are formed on the basis of the structure shown; Figure 8 A schematic diagram of a local cross-sectional structure formed after a second laser treatment is performed in a method for manufacturing a photovoltaic cell according to an embodiment of the present disclosure; Fig. 9 For Figure 8 A schematic diagram of a partial cross-sectional structure formed by etching the first surface based on the structure shown; Fig.10 For Fig. 9 A schematic diagram of a partial cross-sectional structure formed by texturing the first surface and the second surface based on the structure shown; Fig.11 For Fig.10 A schematic diagram of a partial cross-sectional structure formed after cleaning the second surface based on the structure shown.

[0022] Description of reference numerals: 100, substrate; 110, first surface; 120, second surface; 130, third velvet surface; 140, first laser area; 150, first non-laser area; 160, second laser area; 170, second non-laser area; 101, doped layer; 111, activated part; 121, doped part; 102, doped polysilicon layer; 103, silicon glass layer; 113, loose part; 104, first groove; 114, first velvet surface; 105, second groove; 115, second velvet surface; 116, first resistance-expansion layer; 126, second resistance-expansion layer; 136, third resistance-expansion layer; 108, second doped layer. DETAILED DESCRIPTION

[0023] As can be seen from the background art, the manufacturing process of photovoltaic cells needs to be simplified, and the photoelectric conversion efficiency of photovoltaic cells needs to be improved.

[0024] The present disclosure provides a photovoltaic cell and a manufacturing method thereof. In the manufacturing method, on the one hand, a first laser treatment is used to activate a part of the doped layer, so that the doping concentration of the first doping element in the part of the doped layer is reduced to improve the orderliness of the lattice in the part of the doped layer. In other words, compared with the doped part, the doping concentration of the doping element in the activated part is lower, so that the overall orderliness of the lattice in the activated part is stronger, and thus, under the same etching conditions, the doped part is easier to be etched. On this basis, when the first surface is subsequently subjected to the first etching treatment, the etching rate of the first etching treatment on the activated part with a lower doping concentration of the first doping element is much higher than that of the doped part, so that the activation part can be removed and the first velvet surface can be formed with the doped part as a dead layer without the need for an additional mask, which is conducive to simplifying the manufacturing process of the photovoltaic cell. In addition, compared with the use of a laser film opening process to remove part of the doped layer, the combined effect of the first laser treatment and the first etching treatment is conducive to reducing the laser damage caused by the laser to the first surface, thereby helping to reduce the surface defect state density of the first surface, so as to improve the photoelectric conversion efficiency of the photovoltaic cell finally formed. Moreover, the formation of a selective emitter structure in which only a part of the first surface retains the doped part is conducive to reducing the contact resistance between the subsequently formed electrode and the doped part, and reducing the probability of carrier recombination in other areas of the first surface. On the other hand, the second laser treatment is used to modify part of the silicon glass layer into a loose part. On this basis, when the second etching treatment is subsequently performed on at least the second surface, the second etching treatment has a much higher etching rate for the loose part with a higher degree of looseness and porosity than the remaining silicon glass layer. Therefore, without the need to set an additional mask, the remaining silicon glass layer can be used as a protective layer to remove the loose part and the doped polysilicon layer opposite to the loose part, and form a second velvet surface, which is conducive to simplifying the manufacturing process of photovoltaic cells. Moreover, removing the doped polysilicon layer opposite to the loose part is conducive to avoiding the parasitic absorption of light by the removed doped polysilicon layer.

[0025] In the description of the embodiments of the present disclosure, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present disclosure, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0026] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present disclosure. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0027] In the description of the embodiments of the present disclosure, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0028] In the description of the embodiments of the present disclosure, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0029] In the description of the embodiments of the present disclosure, the orientations or positional relationships indicated by technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", and "circumferential" are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the embodiments of the present disclosure and simplifying the description. They do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the embodiments of the present disclosure.

[0030] In the description of the embodiments of the present disclosure, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to the specific circumstances.

[0031] In the accompanying drawings corresponding to the embodiments of the present disclosure, the thickness and area of ​​the layers are exaggerated for better understanding and ease of description. When describing a component (such as a layer, film, region or substrate) on another component or on the surface of another component, the component may be "directly" located on the surface of the other component, or a third component may exist between the two components. On the contrary, when describing a component on the surface of another component or when another component is formed or provided on the surface of a component, it means that there is no third component between the two components. In addition, when describing a component as being "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a partial edge of the entire surface.

[0032] In the description of the embodiments of the present disclosure, when a component "includes" another component, unless otherwise specified, other components are not excluded, and other components may be further included. In addition, when a component such as a layer, film, region, or plate is referred to as being "on / located on" another component, it may be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or another component may exist in between. In addition, when a component such as a layer, film, region, or plate is "directly located on" another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it means that no other components are located in between.

[0033] The terms used in the description of the various embodiments described herein are only used to describe specific embodiments and are not intended to be limiting. As used in the description of the various embodiments described and in the appended claims, "the components" are also intended to include plural forms unless the context clearly indicates otherwise. Among them, components include components such as layers, films, regions, or plates.

[0034] The following will describe the various embodiments of the present disclosure in detail with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that in the various embodiments of the present disclosure, many technical details are provided in order to enable the reader to better understand the embodiments of the present disclosure. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the embodiments of the present disclosure can be implemented.

[0035] An embodiment of the present disclosure provides a method for manufacturing a photovoltaic cell. The method for manufacturing a photovoltaic cell provided by an embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings. Figures 1 to 11 A schematic diagram of a partial cross-sectional structure corresponding to each step in a method for manufacturing a photovoltaic cell is provided for one embodiment of the present disclosure.

[0036] Combined with reference Figures 1 to 11 , the manufacturing method of the photovoltaic cell comprises at least the following steps: Step S1: Reference Figure 1 , Figure 1 A schematic diagram of a partial cross-sectional structure of a substrate provided in a method for manufacturing a photovoltaic cell according to an embodiment of the present disclosure is provided. A substrate 100 is provided. The substrate 100 has a first surface 110 and a second surface 120 that are opposite to each other.

[0037] In some embodiments, in step S1, the material of the substrate 100 may be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, for example, silicon or germanium. Among them, the elemental semiconductor material may be single crystalline, polycrystalline, amorphous or microcrystalline (a state having both single crystalline and amorphous states is called microcrystalline), for example, silicon may be at least one of single crystalline silicon, polycrystalline silicon, amorphous silicon or microcrystalline silicon. In other embodiments, the material of the substrate 100 may also be a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, silicon germanium, silicon carbide, gallium arsenide, indium gallium, perovskite, cadmium telluride, copper indium selenide and other materials. The following is an exemplary description using silicon as the material of the substrate 100.

[0038] Step S2: Reference Figure 2 , Figure 2 A schematic diagram of a partial cross-sectional structure formed after at least a first surface is doped in a method for manufacturing a photovoltaic cell according to an embodiment of the present disclosure, wherein at least the first surface 110 is doped to form a doping layer 101 having a first doping element.

[0039] Step S3: Combine with reference Figure 2 and Figure 3 , Figure 3 A schematic diagram of a local cross-sectional structure formed after a first laser treatment is performed in a method for manufacturing a photovoltaic cell according to an embodiment of the present disclosure, wherein a first laser treatment is performed on a portion of a doping layer 101 to form an activation portion 111, and the remaining doping layer 101 serves as a doping portion 121, and the doping concentration of the first doping element in the activation portion 111 is lower than the doping concentration in the doping portion 121.

[0040] Step S4: Combine with reference Figure 3 and Figure 4 , Figure 4 A schematic diagram of a local cross-sectional structure formed after a first etching treatment is performed in a photovoltaic cell manufacturing method according to an embodiment of the present disclosure. The first surface 110 is subjected to a first etching treatment with the doped portion 121 as a dead layer to remove the activated portion 111 and form a first velvet surface 114.

[0041] Step S5: Combine with reference Figures 4 to 7 , a doped polysilicon layer 102 having a second doping element and a silicon glass layer 103 are sequentially formed at least on one side of the substrate 100 away from the doping portion 121 .

[0042] It should be noted that Figure 5 A schematic diagram of a partial cross-sectional structure formed after at least a first surface is oxidized in a method for manufacturing a photovoltaic cell according to an embodiment of the present disclosure; Figure 6 For Figure 5 A schematic diagram of a partial cross-sectional structure formed by polishing the second surface based on the structure shown; Figure 7 For Figure 6 A schematic diagram of a local cross-sectional structure in which a doped polysilicon layer and a silicon glass layer are formed on the basis of the structure shown.

[0043] Step S6: Reference Figure 8 , Figure 8 A schematic diagram of a local cross-sectional structure formed after a second laser treatment is performed in a method for manufacturing a photovoltaic cell according to an embodiment of the present disclosure, wherein the second laser treatment is performed on at least a portion of the silicon glass layer 103 to form a loose portion 113 .

[0044] Step S7: Combine with reference Figures 8 to 11 , using the remaining silicon glass layer 103 as a protective layer, at least the second surface 120 is subjected to a second etching process to remove the loose portion 113 and the doped polysilicon layer 102 directly opposite to the loose portion 113 , and form a second velvet surface 115 .

[0045] The first doping element and the second doping element are of different types, and the first laser treatment and the second laser treatment use different types of lasers.

[0046] It should be noted that Fig. 9 For Figure 8 A schematic diagram of a partial cross-sectional structure formed by etching the first surface based on the structure shown; Fig.10 For Fig. 9 A schematic diagram of a partial cross-sectional structure formed by texturing the first surface and the second surface based on the structure shown; Fig.11 For Fig.10 A schematic diagram of a partial cross-sectional structure formed after cleaning the second surface based on the structure shown.

[0047] It is worth noting that not only the first laser treatment and the second laser treatment use different types of lasers, but also the first laser treatment and the second laser treatment are directed to different objects.

[0048] Specifically, in step S3, the first laser treatment is performed on a portion of the doped layer 101 to activate the portion of the doped layer 101, thereby reducing the doping concentration of the first doping element in the portion of the doped layer 101 and improving the orderliness of the lattice in the portion of the doped layer 101, thereby converting the portion of the doped layer 101 into an activated portion 111, and the remaining doped layer 101 not targeted by the first laser treatment is used as the doped portion 121. In other words, compared with the doped portion 121, the doping concentration of the doping element in the activated portion 111 is lower, so that the overall orderliness of the lattice in the activated portion 111 is higher, and therefore, under the same etching conditions, the doped portion 121 is more easily etched.

[0049] On this basis, when the first surface 110 is subjected to the first etching treatment in the subsequent step S4, the etching rate of the first etching treatment on the activation part 111 with a lower doping concentration of the first doping element is much higher than that on the doping part 121, so that the activation part 111 can be removed and the first velvet surface 114 can be formed by using the doping part 121 as a dead layer without setting an additional mask, which is conducive to simplifying the manufacturing process of the photovoltaic cell. In addition, compared with the use of a laser film opening process to remove part of the doping layer 101, that is, directly using a laser to ablate part of the doping layer 101 to form a selective emitter structure in which only a part of the first surface 110 retains the doping layer 101, in the manufacturing method provided by an embodiment of the present disclosure, by means of the combined effect of the first laser treatment and the first etching treatment, it is conducive to reducing the laser damage caused by the laser to the first surface 110. In other words, compared with the laser used in the laser film opening process, the laser used in the first laser treatment causes lower laser damage to the first surface 110, which is conducive to reducing the surface defect state density of the first surface 110, so as to improve the photoelectric conversion efficiency of the photovoltaic cell finally formed.

[0050] Moreover, after step S3, a selective emitter structure is formed in which the doping layer 101 is retained only on a partial area of ​​the first surface 110, that is, the doping part 121. This is beneficial for reducing the contact resistance between the subsequently formed electrode and the doping part 121 while reducing the probability of carrier recombination in other areas of the first surface 110, so as to improve the photoelectric conversion efficiency of the photovoltaic cell finally formed.

[0051] In step S6, the second laser treatment is performed on at least a portion of the silicon glass layer 103, so that the portion of the silicon glass layer 103 is modified into a loose portion 113, for example, the looseness and porosity of the loose portion 113 is higher than the looseness and porosity of the remaining silicon glass layer 103. On this basis, when the second surface 120 is subjected to the second etching treatment in the subsequent step S7, the etching rate of the second etching treatment on the loose portion 113 with a higher looseness and porosity is much higher than that of the remaining silicon glass layer 103, so that the loose portion 113 and the doped polysilicon layer 102 directly opposite to the loose portion 113 can be removed and the second velvet surface 115 can be formed by using the remaining silicon glass layer 103 as a protective layer without the need for an additional mask, which is conducive to simplifying the manufacturing process of the photovoltaic cell.

[0052] Moreover, removing the doped polysilicon layer 102 that is opposite to the loose portion 113 is beneficial to avoiding parasitic absorption of light by the removed doped polysilicon layer 102, and the exposed second velvet surface 115 can improve the absorption and utilization rate of light, and is also beneficial to ensuring a lower contact resistance between the subsequently formed electrode and the remaining doped polysilicon layer 102, thereby improving the photoelectric conversion efficiency of the photovoltaic cell finally formed.

[0053] It is worth emphasizing that the purpose of the first laser treatment in step S3 is to activate part of the doped layer 101, and what is changed is the doping concentration of the first doping element in the part of the doped layer 101, and the lattice order in the part of the doped layer 101, so that the doped layer 101 with the reduced doping concentration of the first doping element is used as the activated portion 111. Different from this, the purpose of the second laser treatment in step S6 is to modify at least part of the silicon glass layer 103, and what is changed is the looseness and porosity of part of the silicon glass layer 103, so that the silicon glass layer 103 with increased looseness and porosity is used as the loose portion 113.

[0054] In some cases, the doping concentration of the doping element in the activation portion 111 is lower than the doping concentration in the doping portion 121, which means that: taking the surface of the activation portion 111 away from the substrate 100 as the first reference plane, and taking the surface of the doping portion 121 away from the substrate 100 as the second reference plane, compared with the effective doping concentration of the doping element in the doping portion 121 within a depth of 100 nm from the second reference plane toward the substrate 100, the effective doping concentration of the doping element in the activation portion 111 within a depth of 100 nm from the first reference plane toward the substrate 100 is lower, so that the overall order of the lattice in the activation portion 111 is stronger.

[0055] In some examples, the doping concentration of the doping element in the activation portion 111 is a first doping concentration, and the doping concentration of the doping element in the doping portion 121 is a second doping concentration. The ratio of the second doping concentration to the first doping concentration can be 2 to 100, for example, it can be 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190 or 195, etc.

[0056] In some examples, an effective doping concentration in the activation portion 111 and the doping portion 121 is tested by an ECV (electrochemical capacitance-voltage profiler) test, and the measured effective doping concentration of the doping element in the activation portion 111 within a depth of 100 nm from the first reference surface toward the substrate 100 is less than 5×10 19 atom / cm 3 The effective doping concentration of the doping element in the doping portion 121 within a depth of 100 nm from the second reference plane toward the substrate 100 is greater than 5×10 18 atom / cm 3 .

[0057] It should be noted that, in the first etching treatment, using the same etching conditions to treat the doping part 121 and the activation part 111 means using the same etching solution to treat the doping part 121 and the activation part 111, and the treatment time of the doping part 121 and the activation part 111 is the same.

[0058] In some cases, under the same etching solution, the etching depth of the activated portion 111 per unit time is much greater than the etching depth of the doped portion 121. Therefore, the first etching process has a much higher etching rate on the activated portion 111 having a lower doping concentration of the first doping element than on the doped portion.

[0059] In some examples, under the same etching solution, the ratio of the etching depth of the activated portion 111 to the etching depth of the doped portion 121 per unit time is greater than or equal to 10. In one example, the activated portion 111 and the doped portion 121 are simultaneously etched for about 600 seconds using the same etching solution, the activated portion 111 is etched to a depth of about 2 μm, and the doped portion 121 is etched to a depth of about 100 nm. In other words, compared with the activated portion 111, the doped portion 121 can be regarded as being almost not etched. In the process of the first etching treatment, when the activated portion 111 is completely removed and the first velvet is formed, at least most of the thickness of the doped portion 121 is not etched.

[0060] In some cases, the looseness and porosity of the loose portion 113 is higher than that of the remaining silicon glass layer 103, which means that, from a microscopic perspective, a cracked film can be seen in the loose portion 113, for example, cracks or fragments can be seen in the loose portion 113, and the maximum size of the fragments does not exceed 100 μm. The looseness and porosity of the loose portion 113 from a microscopic perspective can be obtained using a scanning electron microscope (SEM).

[0061] The following is a detailed description of each step in the method for preparing a photovoltaic cell provided in an embodiment of the present disclosure: In some embodiments, the substrate 100 may be an N-type semiconductor substrate doped with an N-type doping element, the first doping element is a P-type doping element, and the second doping element is an N-type doping element. In some examples, the N-type doping element may be at least one of the V-group 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 the III-group elements such as boron (B), aluminum (Al), gallium (Ga), or gallium (In).

[0062] In one example, the doping treatment performed on at least the first surface 110 in step S2 can be a boron diffusion treatment, so that at least a portion of the substrate 100 doped with the boron (B) element is regarded as a doped layer 101, and the doped layer 101 can be regarded as a boron diffusion layer; in step S4, the material of the doped polysilicon layer 102 can be N-type polysilicon, and the material of the silicon glass layer 103 can be phospho-silicate glass.

[0063] In other embodiments, the substrate may also be a P-type semiconductor substrate doped with a P-type doping element, the first doping element of the doping layer is an N-type doping element, and the second doping element of the doped polysilicon layer is a P-type doping element.

[0064] In some embodiments, the photovoltaic cell is a single-sided cell. In step S1, the first surface 110 can be regarded as the front side of the photovoltaic cell, that is, the first surface 110 can be used as a light-receiving surface for receiving incident light, and the second surface 120 can be used as a backlight surface. In other embodiments, the photovoltaic cell is a double-sided cell, then both the first surface 110 and the second surface 120 can be used as light-receiving surfaces, and both can be used to receive incident light. It can be understood that the backlight surface described in an embodiment of the present disclosure can also receive incident light, but the degree of receiving the incident light is weaker than the degree of receiving the incident light by the light-receiving surface, and therefore it is defined as the backlight surface. The following exemplary description is given with the first surface 110 as the light-receiving surface and the second surface 120 as the backlight surface.

[0065] In some embodiments, reference Figure 3 In step S3, the first laser treatment may be performed using red nano laser, green nano laser or purple nano laser; Figure 8 In step S6, the second laser treatment may be performed by using a purple laser, a green laser, a green laser or a purple laser. In this way, the doping concentration of the first doping element in a part of the doping layer 101 is reduced by using a red laser, a green laser or a purple laser, so that the doping layer 101 with the reduced doping concentration of the first doping element is used as the activation part 111 to improve the overall order of the lattice in the activation part 111; the looseness and porosity of a part of the silicon glass layer 103 is changed by using a purple laser, a green laser, a green laser or a purple laser, so that the silicon glass layer 103 with increased looseness and porosity is used as the loose part 113.

[0066] It is worth noting that red nanolaser, green nanolaser or purple nanolaser are all nanosecond lasers, that is, the laser used in the first laser treatment can be a short pulse laser; purple laser and green laser are both picosecond lasers, green laser or purple laser are both femtosecond lasers, and picosecond laser and femtosecond laser are both ultrashort pulse lasers, that is, the laser used in the second laser treatment can be an ultrashort pulse laser. In other words, the pulse width of the laser used in the first laser treatment is greater than the pulse width of the laser used in the second laser treatment.

[0067] In some examples, the wavelength range of the red-nano laser used in the first laser treatment can be 700nm~1500nm, for example, it can be 730nm, 750nm, 780nm, 800nm, 820nm, 850nm, 880nm, 900nm, 930nm, 950nm, 960nm, 1000nm, 1020nm, 1050nm, 1060nm, 1200nm, 1230nm, 1250nm, 1270nm, 1300nm, 1320nm, 1350nm, 1370nm, 1420nm, 1450nm or 1480nm, etc.

[0068] In some examples, the wavelength range of the green nano laser used in the first laser treatment, and the green skin laser and green flying laser used in the second laser treatment can all be 492nm~577nm, for example, 493nm, 495nm, 496nm, 500nm, 502nm, 505nm, 508nm, 510nm, 513nm, 515nm, 516nm, 520nm, 522nm, 525nm, 528nm, 530nm, 532nm, 535nm, 538nm, 540nm, 542nm, 545nm, 548nm, 550nm, 552nm, 555nm, 558nm, 560nm, 562nm, 565nm, 568nm, 570nm, 572nm, 575nm or 578nm, etc.

[0069] In some examples, the wavelength range of the purple laser used in the first laser treatment, and the purple laser and purple fly laser used in the second laser treatment can be 200nm~400nm, for example, it can be 205nm, 210nm, 215nm, 220nm, 225nm, 230nm, 235nm, 240nm, 245nm, 250nm, 255nm, 260nm, 265nm, 270nm, 275nm, 280nm, 285nm, 290nm, 295nm, 300nm, 305nm, 310nm, 315nm, 320nm, 325nm, 330nm, 335nm, 340nm, 345nm, 350nm, 355nm, 360nm, 365nm, 370nm, 375nm, 380nm, 385nm, 390nm or 395nm, etc.

[0070] In some embodiments, in conjunction with reference Figure 3 and Figure 4 The step of forming the first suede surface 114 in step S4 may include: forming a first groove 104 whose bottom surface is the first suede surface 114 .

[0071] It is worth noting that the etching rate of the activated portion 111 by the first etching treatment is much higher than the etching rate of the doped portion 121. On this basis, in step S4, the doped portion 121 is used as a barrier layer, which not only removes the activated portion 111, but also further etches the first surface 110 exposed after the activated portion 111 is removed to form a first groove 104. Relative to the substrate 100 directly opposite to the doped portion 121, the first groove 104 is further recessed into the substrate 100, that is, it is recessed in the direction from the first surface 110 to the second surface 120. In other words, the first surface 110 includes the first laser area 140 and the first non-laser area 150 alternately arranged along the first direction X, the doped portion 121 not etched by the first etching process is located in the first non-laser area 150, and the first groove 104 is located in the first laser area 140. After step S4, the surface of the substrate 100 located in the first non-laser area 150 is higher than the surface of the substrate 100 located in the first laser area 140, so as to form the first groove 104 in the first laser area 140. In addition, based on the further etching of the substrate 100 directly opposite to the activated portion 111 by the first etching process, at least the bottom surface of the first groove 104 can have a first velvet surface 114.

[0072] Thus, on the one hand, the first velvet surface 114 not only reduces the reflectivity of the bottom surface of the first groove 104, but also forms a light trap, thereby enhancing the absorption effect of the first velvet surface 114 on the incident light. On the other hand, by further taking advantage of the fact that the first groove 104 is recessed into the substrate 100, the light incident into the first groove 104 is less likely to be reflected outside the photovoltaic cell, thereby further improving the absorption utilization rate of the incident light by the first groove 104. Therefore, with the cooperation of the first groove 104 and the first velvet surface 114, it is beneficial to increase the photoelectric conversion efficiency of the photovoltaic cell.

[0073] It is worth noting that, based on the control of the concentration of the etching solution used in the first etching treatment and / or the treatment time of the first etching treatment, it is possible to control whether the first etching treatment further etches the first surface 110 exposed after the activation portion 111 is removed, that is, to control whether the first groove 104 is further formed on the first laser zone 140 of the substrate 100; further, it is also possible to control the degree of etching of the substrate 100 directly opposite to the activation portion 111 by the first etching treatment, that is, to control the depth of the formed first groove 104.

[0074] In some examples, the processing time of the first etching process can be 600s~750s, for example, it can be 610s, 620s, 630s, 640s, 650s, 660s, 670s, 680s, 690s, 700s, 710s, 720s, 730s or 740s.

[0075] In some examples, the depth of the first groove 104 may be 2.5 μm to 4 μm, for example, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, 3 μm, 3.1 μm, 3.2 μm, 3.3 μm, 3.4 μm, 3.5 μm, 3.6 μm, 3.7 μm, 3.8 μm or 3.9 μm.

[0076] It should be noted that Figure 4 In the example, the doping portion 121 is retained on the first non-laser area 150 of the substrate 100 and the first groove 104 is formed on the first laser area 140 of the substrate 100. In actual applications, the surfaces of the first non-laser area and the first laser area of ​​the substrate can be flat.

[0077] In some embodiments, in conjunction with reference Figures 8 to 11 The step of forming the second suede surface 115 in step S7 may include: forming a second groove 105 whose bottom surface is the second suede surface 115 .

[0078] It is worth noting that the etching rate of the second etching treatment on the loose portion 113 is much higher than the etching rate on the remaining silicon glass layer 103. On this basis, in step S7, the remaining silicon glass layer 103 is used as a protective layer, which not only removes the loose portion 113, but also further etches the second surface 120 exposed after the loose portion 113 is removed to form a second groove 105. Relative to the substrate 100 directly opposite to the loose portion 113, the second groove 105 is further recessed into the substrate 100, that is, it is recessed in the direction from the second surface 120 to the first surface 110. In other words, the second surface 120 includes the second laser area 160 and the second non-laser area 170 alternately arranged along the first direction X, the silicon glass layer 103 not etched by the second etching process is located in the second non-laser area 170, and the second groove 105 is located in the second laser area 160. After step S7, the surface of the substrate 100 located in the second non-laser area 170 is higher than the surface of the substrate 100 located in the second laser area 160, so as to form the second groove 105 in the second laser area 160. In addition, based on the further etching of the substrate 100 directly opposite to the loose portion 113 by the second etching process, at least the bottom surface of the second groove 105 can have a second velvet surface 115.

[0079] Thus, on the one hand, the second velvet surface 115 not only reduces the reflectivity of the bottom surface of the second groove 105, but also forms a light trap to enhance the absorption effect of the second velvet surface 115 on the incident light, and on the other hand, further by virtue of the second groove 105 being recessed into the substrate 100, the light incident into the second groove 105 is less likely to be reflected outside the photovoltaic cell, further enhancing the absorption utilization rate of the incident light by the second groove 105. Therefore, with the cooperation of the second groove 105 and the second velvet surface 115, it is beneficial to increase the photoelectric conversion efficiency of the photovoltaic cell.

[0080] It is worth noting that, based on the control of the concentration of the etching solution used in the second etching treatment and / or the treatment time of the second etching treatment, it is possible to control whether the second etching treatment further etches the second surface 120 exposed after the loose portion 113 is removed, that is, to control whether a second groove 105 is further formed on the second laser zone 160 of the substrate 100; further, it is also possible to control the degree of etching of the substrate 100 opposite to the loose portion 113 by the second etching treatment, that is, to control the depth of the formed second groove 105.

[0081] In some examples, the processing time of the second etching process can be 600s~750s, for example, it can be 610s, 620s, 630s, 640s, 650s, 660s, 670s, 680s, 690s, 700s, 710s, 720s, 730s or 740s.

[0082] In some examples, the depth of the second groove 105 may be 2 μm to 3 μm, for example, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, or 2.9 μm.

[0083] It should be noted that Fig.10 In the example, the silicon glass layer 103 is retained on the second non-laser area 170 of the substrate 100, and the second groove 105 is formed on the second laser area 160 of the substrate 100. In actual applications, the surfaces of the second non-laser area and the second laser area of ​​the substrate can be flat.

[0084] In addition, based on the first groove 104 with the first velvet surface 114 on the bottom surface formed in step S4, a second groove 105 with the second velvet surface 115 on the bottom surface can be further formed in step S7. In other words, the first surface 110 having the first groove 104 and the second surface 120 having the second groove 105 can exist simultaneously in the finally formed photovoltaic cell. This is beneficial to simultaneously improve the absorption utilization rate of the first surface 110 and the absorption utilization rate of the second surface 120 for the incident light, thereby helping to improve the bifaciality of the photovoltaic cell.

[0085] In practical applications, when a first groove having a first velvet surface as the bottom surface is formed in step S4, a second velvet surface flush with the substrate surface facing the remaining silicon glass layer can be formed in step S7; or, when a first velvet surface flush with the substrate surface facing the doped portion is formed in step S4, a second groove having a second velvet surface as the bottom surface can be formed in step S7; or, when a first velvet surface flush with the substrate surface facing the doped portion is formed in step S4, a second velvet surface flush with the substrate surface facing the remaining silicon glass layer can be formed in step S7. It should be noted that the above-mentioned "flush" means that the height difference between the two surfaces is extremely low, or even zero.

[0086] In some embodiments, in conjunction with reference Figure 2 and Figure 3 In the step of performing the first laser treatment in step S3, an oxide layer (not shown in the figure) is formed on the doping layer 101; Figure 3 and Figure 4 Step S4 of performing a first etching treatment on the first surface 110 may include: etching the first surface 110 using a first chain hydrofluoric acid process to remove the oxide layer; and then etching the first surface 110 using a first texturing process to remove the activation portion 111 and form a first texturing surface 114.

[0087] It is worth noting that due to the effect of the laser used in the first laser treatment on the doping layer 101, a portion of the doping layer 101 away from the surface of the substrate 100 is easily oxidized by heat, thereby forming an oxide layer on the doping layer 101. In some examples, the oxide layer may be made of silicon oxide.

[0088] On this basis, the first etching treatment includes two steps of etching process, firstly, the first chain hydrofluoric acid process is used to etch the first surface 110, and then the first texturing process is used to etch the first surface 110, which is conducive to the targeted removal of the oxide layer and the activation part 111, respectively, and is conducive to improving the etching accuracy of the first etching process. In some examples, step S4 ultimately needs to form a first groove 104 with a first velvet surface 114 as the bottom surface. The first etching treatment is designed to include two steps of etching process, which is conducive to forming a good step morphology on the first surface 110, that is, forming a first groove 104 with controllable surface morphology, for example, it is conducive to forming a first groove 104 with almost the same depth in each area.

[0089] In other embodiments, the step of performing a first etching process on the first surface includes: etching the first surface using a first texturing process to remove the activated portion and form a first velvet surface. In other words, the first etching process can be a first texturing process, that is, directly using the first texturing process to remove the oxide layer and the activated portion and form a first velvet surface.

[0090] In some embodiments, the first surface 110 includes a first laser area 140 and a first non-laser area 150 arranged alternately along the first direction X, and the second surface 120 includes a second laser area 160 and a second non-laser area 170 arranged alternately along the first direction X; after performing step S4 to form the first velvet surface 114, the first surface 110 located in the first non-laser area 150 is still the third velvet surface 130 (refer to Figure 1 ), the third suede surface 130 has a third pyramid structure, the first suede surface 114 has a first pyramid structure, and the size of the third pyramid structure is greater than that of the first pyramid structure.

[0091] It is worth noting that the entire first surface 110 of the substrate 100 passed through in step S1 can be the third velvet surface 130. After steps S2 to S4 are performed, based on the etching effect of the first etching process on the substrate 100, that is, further etching of the third velvet surface 130 located in the first laser area 140, the third velvet surface 130 located in the first laser area 140 is transformed into the first velvet surface 114. In this way, it is beneficial to improve the light trapping effect of the first velvet surface 114 by means of the first pyramid structure with a smaller size.

[0092] In some embodiments, reference Figure 1 and Figure 2 , the first surface 110 and the second surface 120 provided in step S1 can both be the third velvet surface 130; Figures 4 to 6 After forming the first velvet surface 114 in step S4 and before forming the doped polysilicon layer 102 in step S5, the manufacturing method may further include: polishing the second surface 120 to form a polished surface; Figure 6 and Figure 7 The steps of forming the doped polysilicon layer 102 and the silicon glass layer 103 include: forming the doped polysilicon layer 102 on the polishing surface, and forming the silicon glass layer 103 on the side of the doped polysilicon layer 102 away from the polishing surface.

[0093] It is worth noting that the polishing surface has a high flatness. Forming a doped polysilicon layer 102 on the polishing surface is more conducive to improving the uniformity of the doped polysilicon layer 102, that is, forming a doped polysilicon layer 102 with almost uniform thickness in each region, which is beneficial to improving the passivation effect of the doped polysilicon layer 102 on the surface of the substrate 100, thereby helping to improve the photoelectric conversion efficiency of the photovoltaic cell finally formed.

[0094] In some cases, reference Figure 2 In the step S2 of at least performing a doping treatment on the first surface 110, a doping treatment is also performed on the second surface 120 to form a second doping layer 108 having a first doping element on the second surface 120. The doping layer 101 formed on the first surface 110 can be regarded as a first doping layer; in combination with reference Figures 4 to 6In the step of polishing the second surface 120 , the second doping layer 108 is removed.

[0095] In some cases, reference Figure 5 After forming the first suede surface 114 in step S4 and before forming the polishing surface, the manufacturing method may further include: performing an oxidation treatment on at least the first surface 110 to form a first resistance layer 116 on the doped portion 121 and forming a second resistance layer 126 on the first suede surface 114 .

[0096] It is worth noting that the first resistance layer 116 is formed by oxidation treatment of a partial thickness of the doped portion 121. In some examples, the material of the first resistance layer 116 may be borosilicate glass. The second resistance layer 126 is formed by oxidation treatment of a partial thickness of the substrate 100. In some examples, the material of the second resistance layer 126 may be silicon oxide.

[0097] In addition, at least in the step of oxidizing the first surface 110, the doping elements in the doping portion 121 are further diffused into the substrate 100, which is conducive to deepening the junction depth of the doping portion 121, so as to improve the junction depth of the PN junction formed by the doping portion 121 and the substrate 100. Moreover, the doping concentration of the doping elements in the doping portion 121 can be slightly reduced to reduce the defect state density at the contact point between the subsequently formed electrode and the doping portion 121, so as to improve the contact performance between the electrode and the doping portion 121. On this basis, refer to Figure 7 , the step S5 of forming the doped polysilicon layer 102 and the silicon glass layer 103 may also include: forming the doped polysilicon layer 102 on both the first resistance diffusion layer 116 and the second resistance diffusion layer 126, and forming the silicon glass layer 103 on both sides of the doped polysilicon layer 102 away from the first resistance diffusion layer 116 and the second resistance diffusion layer 126. It is worth noting that in the step of forming the doped polysilicon layer 102 and the silicon glass layer 103, the second doping element will gradually diffuse into the doped polysilicon layer 102 due to the influence of high temperature diffusion. In this way, on the one hand, the first diffusion barrier layer 116 located on the doping portion 121 is conducive to blocking the further diffusion of the second doping element into the doping portion 121, avoiding the loss of the second doping element, and avoiding the modification of the doping portion 121 due to the diffusion of the second doping element, for example, avoiding the transformation of the doping portion 121 from P-type to N-type; on the other hand, the second diffusion barrier layer 126 located on the first velvet surface 114 is conducive to blocking the further diffusion of the second doping element into the substrate 100, for example, the first laser zone 140, avoiding the loss of the second doping element.

[0098] In other cases, after forming the first velvet surface in step S4 and before forming the polishing surface, the manufacturing method may further include: performing an oxidation treatment on at least the first surface to form a first diffusion barrier layer on the doped portion, and forming a second diffusion barrier layer on the first velvet surface; the surface formed by the first diffusion barrier layer and the second diffusion barrier layer includes an edge region and a central region surrounded by the edge region, and the step of forming a doped polysilicon layer and a silicon glass layer may further include: forming a doped polysilicon layer on the edge region, and forming a silicon glass layer on the side of the doped polysilicon layer away from the edge region. In other words, in step S5, in the step of forming a doped polysilicon layer and a silicon glass layer on the second surface, due to the wrap-around plating phenomenon, a doped polysilicon layer and a silicon glass layer are also formed in sequence on the edge region of the surface formed by the first diffusion barrier layer and the second diffusion barrier layer. In this way, the first diffusion barrier layer located on the doped portion is also conducive to blocking the further diffusion of the second doping element into the doped portion, and the second diffusion barrier layer located on the first velvet surface is also conducive to blocking the further diffusion of the second doping element into the substrate.

[0099] In some examples, reference Figure 2 In step S2, a second doping layer 108 having a first doping element is further formed on the second surface 120; based on this, refer to Figure 5 , in the step of at least oxidizing the first surface 110, the second doped layer 108 is also oxidized to form a third resistance expansion layer 136 on the side of the second doped layer 108 away from the second surface 120. It is worth noting that the second resistance expansion layer 126 and the third resistance expansion layer 136 can be formed simultaneously through the same oxidation step. In some examples, the material of the third resistance expansion layer 136 and the material of the second resistance expansion layer 126 can both be silicon oxide. Further, in the step of polishing the second surface 120, not only the second doped layer 108 is removed, but also the third resistance expansion layer 136 is removed.

[0100] In some cases, during the oxidation treatment step, the temperature is controlled at 1000°C to 1100°C, for example, 1010°C, 1020°C, 1030°C, 1040°C, 1050°C, 1060°C, 1070°C, 1080°C or 1090°C.

[0101] In some cases, reference Figure 7, the step of forming the doped polysilicon layer 102 and the silicon glass layer 103 may include: forming a semiconductor layer (not shown in the figure) on the first surface 110 and the second surface 120 after step S4, forming a doping source layer (not shown in the figure) having a second doping element on the side of the semiconductor layer away from the substrate 100, and subjecting the semiconductor layer and the doping source layer to high temperature treatment to promote the diffusion of the second doping element into the semiconductor layer, thereby transforming the semiconductor layer into the doped polysilicon layer 102, and transforming the doping source layer into the silicon glass layer 103. In other cases, the step of forming the doped polysilicon layer and the silicon glass layer may include: forming a semiconductor layer (not shown in the figure) on the second surface 120 after step S4, a semiconductor layer is also formed on the edge area of ​​the surface jointly formed by the first barrier layer and the second barrier layer based on the wrap-around plating phenomenon, forming a doping source layer (not shown in the figure) having a second doping element on the side of the semiconductor layer away from the substrate, and subjecting the semiconductor layer and the doping source layer to high temperature treatment to promote the diffusion of the second doping element into the semiconductor layer, thereby transforming the semiconductor layer into the doped polysilicon layer, and transforming the doping source layer into the silicon glass layer.

[0102] In some examples, the material of the semiconductor layer may be amorphous silicon, and the high temperature treatment step further causes the amorphous silicon to crystallize to transform into polycrystalline silicon; in other examples, the material of the semiconductor layer may be polycrystalline silicon.

[0103] In some embodiments, reference Figure 1 The first surface 110 includes a first laser area 140 and a first non-laser area 150 arranged alternately along the first direction X, and the second surface 120 includes a second laser area 160 and a second non-laser area 170 arranged alternately along the first direction X. Figure 3 The step S3 of performing a first laser treatment on a portion of the doped layer 101 may include: performing a first laser treatment on the doped layer 101 located in the first laser region 140 to form an activated portion 111 located in the first laser region 140; Figure 8 The step of performing a second laser treatment on at least a portion of the silicon glass layer 103 may include: performing a second laser treatment on the silicon glass layer 103 located in the second laser region 160 to form a loose portion 113 located in the second laser region 160 .

[0104] In this way, in the photovoltaic cell finally formed, the doping part 121 is only located in the first non-laser area 150, and the doping part 121 can be regarded as a selective emitter located on the first surface 110, which is beneficial to ensure that the subsequent electrode has good current collection efficiency based on the doping part 121, while avoiding the first laser area 140 from being covered by the doping layer 101, thereby avoiding the parasitic absorption of the light incident to the first laser area 140 by the doping layer 101, and improving the utilization rate of the first surface 110 for the incident light, so as to improve the photoelectric conversion efficiency of the photovoltaic cell.

[0105] In some cases, reference Figure 7 In the step of forming the doped polysilicon layer 102 with the second doping element in step S5, a tunneling layer (not shown in the figure) is also formed between the second surface 120 and the doped polysilicon layer 102. In some examples, the material of the tunneling layer is silicon oxide. On this basis, the second etching process in step S7 also removes the tunneling layer directly opposite to the loose portion 113.

[0106] In this way, in the photovoltaic cell finally formed, the tunneling layer and the doped polysilicon layer 102 are only located in the second non-laser area 170, and the tunneling layer and the doped polysilicon layer 102 form a selective passivation contact structure on the second surface 120, which is beneficial to ensure that the tunneling layer and the doped polysilicon layer 102 have a good passivation effect on the second surface 120, while avoiding the second laser area 160 from being covered by the doped polysilicon layer 102, thereby avoiding the parasitic absorption of the doped polysilicon layer 102 on the light incident to the second laser area 160, improving the utilization rate of the second surface 120 for the incident light, and improving the photoelectric conversion efficiency of the photovoltaic cell.

[0107] In some embodiments, reference Fig.10 or Fig.11 , the first non-laser area 150 and the second non-laser area 170 both include at least the area where the orthographic projection of the electrode (not shown in the figure) on the substrate 100 is located, the area on the first surface 110 other than the first non-laser area 150 is the first laser area 140, and the area on the second surface 120 other than the second non-laser area 170 is the second laser area 160. Among them, in order to ensure that the film layer contacted by the electrode has a large doping concentration or the areas contacted by the electrode are all high-concentration areas, thereby reducing the contact resistance, it is generally set that the orthographic projection area of ​​the first non-laser area 150 and the second non-laser area 170 is greater than or equal to the orthographic projection area of ​​the electrode. In other words, the orthographic projection area of ​​the electrode on the substrate 100 is smaller than the area of ​​the first non-laser area or the second non-laser area, and the orthographic projection position must be within the first non-laser area or the second non-laser area.

[0108] It should be noted that the number of laser zones and the number of non-laser zones can be multiple, and the laser zones and non-laser zones are alternately arranged along a fixed direction. In other words, the laser zones can be located in the interval between adjacent laser zones, and the non-laser zones can also be located in the interval between adjacent laser zones. The laser zones include a first laser zone 140 and a second laser zone 160, and the non-laser zones include a first non-laser zone 150 and a second non-laser zone 170.

[0109] In some embodiments, reference Fig.10 or Fig.11The orthographic projection area of ​​the first laser zone 140 on the substrate 100 and the orthographic projection area of ​​the second laser zone 160 on the substrate 100 may be different. It is worth noting that based on the different types of photovoltaic cells, the different light absorption rates of the first surface 110 and the second surface 120, and the different size designs of the subsequently formed doping part 121 and the doped polysilicon layer 102, the orthographic projection area of ​​the first laser zone 140 on the first surface 110 and the orthographic projection area of ​​the second laser zone 160 on the first surface 110 can be different, that is, the sizes of the first laser zone 140 and the second laser zone 160 are different. In this way, the preparation method provided in one embodiment of the present disclosure is applicable to a variety of photovoltaic cells.

[0110] In one example, the orthographic projection area of ​​the first laser zone on the first surface may be less than or equal to the orthographic projection area of ​​the second laser zone on the first surface; in another example, the orthographic projection area of ​​the first laser zone on the first surface may be greater than the orthographic projection area of ​​the second laser zone on the first surface. It should be noted that the orthographic projection areas of the plurality of first laser zones on the first surface may be the same or different, and may be designed according to actual needs; the orthographic projection areas of the plurality of second laser zones on the first surface may be the same or different, and may also be designed according to actual needs.

[0111] In other embodiments, the orthographic projection of the first laser zone on the first surface does not overlap with the orthographic projection of the second laser zone on the first surface. In other words, the first laser zone and the second laser zone are prevented from facing each other along the second direction, and the second direction is the thickness direction of the photovoltaic cell. In this way, the laser used in the first laser treatment in step S3 and the laser used in the second laser treatment in step S6 are prevented from repeatedly treating the same part of the substrate, so as to avoid repeated overheating and damage to the local part of the substrate, thereby facilitating the improvement of the electrical performance of the photovoltaic cell finally formed.

[0112] In one example, the first laser area can be opposite to the second non-laser area along the second direction, that is, the orthographic projection of the first laser area on the first surface coincides with the orthographic projection of the second non-laser area on the first surface; the first non-laser area can be opposite to the second laser area along the second direction, that is, the orthographic projection of the first non-laser area on the first surface coincides with the orthographic projection of the second laser area on the first surface.

[0113] In other embodiments, the orthographic projection of the first laser zone on the first surface and the orthographic projection of the second laser zone on the first surface may also at least partially overlap.

[0114] It should be noted that, in practical applications, the orthographic projection area of ​​the first laser zone on the first surface is different from the orthographic projection area of ​​the second laser zone on the first surface, and the orthographic projection of the first laser zone on the first surface does not overlap with the orthographic projection of the second laser zone on the first surface, and they can exist in the same photovoltaic cell at the same time; or, the orthographic projection area of ​​the first laser zone on the first surface is different from the orthographic projection area of ​​the second laser zone on the first surface, and the orthographic projection of the first laser zone on the first surface at least partially overlaps with the orthographic projection of the second laser zone on the first surface, and they can exist in the same photovoltaic cell at the same time.

[0115] In some embodiments, in conjunction with reference Fig. 9 and Fig.10 , the step of performing a second etching treatment on at least the second surface 120 may include: etching the first surface 110 using a second chain hydrofluoric acid process to remove the silicon glass layer 103 located on the first surface 110; etching the first surface 110 and the second surface 120 using a second texturing process to remove the doped polysilicon layer 102, the first resistance diffusion layer 116 and the second resistance diffusion layer 126 located on the first surface 110 to expose the first textured surface 114 and the doped portion 121, and removing the loose portion 113 and the doped polysilicon layer 102 located in the second laser zone 160, and forming a second textured surface 115.

[0116] It is worth noting that in step S6, only a portion of the silicon glass layer 103 formed on the second surface 120 is subjected to the second laser treatment to form the loose portion 113, and the silicon glass layer 103 formed on the first surface 110 is not laser treated, that is, the looseness and porosity of the remaining silicon glass layer 103 located on the second surface 120 and the silicon glass layer 103 located on the first surface 110 are not modified by the second laser treatment, and are both lower than the looseness and porosity of the loose portion 113.

[0117] On this basis, the second etching process includes two steps of etching processes. First, the first surface 110 is etched by the second chain hydrofluoric acid process to remove the silicon glass layer 103 located on the first surface 110, which is conducive to avoiding the phenomenon that the subsequent second texturing process is blocked by the silicon glass layer 103 located on the first surface 110 and cannot remove the doped polysilicon layer 102 located on the first surface 110. Then, the remaining silicon glass layer 103 located on the second surface 120 is used as a protective layer, and the first surface 110 and the second surface 120 are etched by the second texturing process to remove the doped polysilicon layer 102, the first resistance diffusion layer 116 and the second resistance diffusion layer 126 located on the first surface 110, and remove the loose part 113 and the doped polysilicon layer 102 located in the second laser area 160, which is conducive to making the number of film layers required to be removed from the first surface 110 and the second surface 120 by the second texturing process both 2 layers, thereby facilitating improving the etching accuracy of the second etching process. In some examples, step S7 ultimately needs to form a second groove 105 whose bottom surface is a second velvet surface 115. Designing the second etching process includes two consecutive etching processes, which is conducive to forming a good step morphology on the second surface 120, that is, forming a second groove 105 with controllable surface morphology, for example, it is conducive to forming a second groove 105 with almost uniform depth in each area.

[0118] In some embodiments, in conjunction with reference Fig.10 and Fig.11 After performing the second texturing process, the manufacturing method may further include: using an acid pickling process to clean the second surface 120 to remove the silicon glass layer 103 located in the second non-laser area 170 to expose the doped polysilicon layer 102 located in the second non-laser area 170.

[0119] In summary, the first laser treatment is used to deepen the doping concentration of the first doping element in the partial doping layer 101. On this basis, when the first surface 110 is subsequently subjected to the first etching treatment, the first etching treatment has a much higher etching rate for the activation portion 111 with a lower doping concentration of the first doping element than the doping portion 121, so that the activation portion 111 can be removed and the first velvet surface 114 can be formed by using the doping portion 121 as a barrier layer without the need for an additional mask, which is conducive to simplifying the manufacturing process of the photovoltaic cell. In addition, compared with the use of a laser film opening process to remove part of the doping layer 101, the combination of the first laser treatment and the first etching treatment is conducive to reducing the laser damage caused by the laser to the first surface 110. Moreover, the formation of a selective emitter structure having a doping portion 121 only in a partial area of ​​the first surface 110 is conducive to reducing the contact resistance between the subsequently formed electrode and the doping portion 121, while reducing the probability of carrier recombination in other areas of the first surface 110.

[0120] The second laser treatment is used to modify the part of the silicon glass layer 103 into a loose part 113. On this basis, when the second etching treatment is subsequently performed on at least the second surface 120, the etching rate of the second etching treatment on the loose part 113 with a higher degree of looseness and porosity is much higher than that of the remaining silicon glass layer 103, so that the loose part 113 and the doped polysilicon layer 102 directly opposite to the loose part 113 can be removed and the second velvet surface 115 can be formed without the need for an additional mask, using the remaining silicon glass layer 103 as a protective layer, which is conducive to simplifying the manufacturing process of the photovoltaic cell. In addition, removing the doped polysilicon layer 102 directly opposite to the loose part 113 is conducive to avoiding the parasitic absorption of light by the removed doped polysilicon layer 102, and the exposed second velvet surface 115 can improve the absorption utilization rate of light, and is also conducive to ensuring a lower contact resistance between the subsequently formed electrode and the remaining doped polysilicon layer 102.

[0121] Another embodiment of the present disclosure further provides a photovoltaic cell, which is prepared by the manufacturing method provided in the above embodiment. The photovoltaic cell provided in another embodiment of the present disclosure will be described in detail below in conjunction with the accompanying drawings. It should be noted that the parts that are the same or corresponding to the above embodiment will not be repeated here.

[0122] The photovoltaic cell includes: a photovoltaic cell formed according to the manufacturing method provided by the above embodiment.

[0123] It is worth noting that the photovoltaic cell can be a cell with a passivation structure such as a TOPCON cell, a PERC cell or a heterojunction cell. The photovoltaic cell is formed according to the manufacturing method provided in the above embodiment, and the first laser treatment and the second laser treatment of different laser types are used successively, which is conducive to forming the doped part 121 located only on a part of the first surface 110 and the doped polysilicon layer 102 located only on a part of the second surface 120 without the need for additional masking, and exposing the first velvet surface 114 on the first surface 110 and the second velvet surface 115 on the second surface 120, so as to improve the utilization rate of the first surface 110 and the second surface 120 for the incident light, thereby improving the photoelectric conversion efficiency of the formed photovoltaic cell.

[0124] In some embodiments, reference Fig.11The photovoltaic cell comprises: a substrate 100 having a first surface 110 and a second surface 120 opposite to each other, the first surface 110 comprising a first laser area 140 and a first non-laser area 150 arranged alternately along a first direction X, the second surface 120 comprising a second laser area 160 and a second non-laser area 170 arranged alternately along the first direction X; a doping portion 121 located on the first non-laser area 150; a doped polysilicon layer 102 located on the second non-laser area 170; a first groove 104 having a first velvet surface 114 on the first laser area 140; and a second groove 105 having a second velvet surface 115 on the second laser area 160.

[0125] Thus, on the one hand, the first velvet surface 114 can enhance the absorption effect of the incident light, and by virtue of the first groove 104 being recessed into the substrate 100, the light incident into the first groove 104 is less likely to be reflected outside the photovoltaic cell, further improving the absorption utilization rate of the first groove 104 to the incident light, and thus, under the cooperation of the first groove 104 and the first velvet surface 114, it is beneficial to increase the absorption utilization rate of the first surface 110 to the incident light. On the other hand, the second velvet surface 115 can enhance the absorption effect of the incident light, and by virtue of the second groove 105 being recessed into the substrate 100, the light incident into the second groove 105 is less likely to be reflected outside the photovoltaic cell, further improving the absorption utilization rate of the second groove 105 to the incident light. Therefore, under the cooperation of the second groove 105 and the second velvet surface 115, it is beneficial to increase the absorption utilization rate of the second surface 120 to the incident light. Such multi-faceted cooperation is beneficial to increase the photoelectric conversion efficiency of the photovoltaic cell.

[0126] In some cases, the depth of the first groove 104 is greater than the depth of the second groove 105 along the second direction Y. In some examples, the depth of the first groove 104 may be 2.5 μm to 4 μm, and the depth of the second groove 105 may be 2 μm to 3 μm.

[0127] In some embodiments, the photovoltaic cell may further include: a tunneling layer located between the second surface 120 and the doped polysilicon layer 102 , wherein the tunneling layer and the doped polysilicon layer 102 form a selective passivation contact structure on the second surface 120 .

[0128] Those skilled in the art can understand that the above-mentioned embodiments are specific examples for implementing the present disclosure, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of the embodiments of the present disclosure. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of the present disclosure, so the protection scope of the embodiments of the present disclosure shall be based on the scope defined in the claims.

Claims

1. A method for manufacturing a photovoltaic cell, characterized in that: include: providing a substrate having opposing first and second sides; Performing a doping treatment on at least the first surface to form a doping layer having a first doping element; Performing a first laser treatment on a portion of the doping layer to form an activated portion, and the remaining doping layer serves as a doping portion, wherein a doping concentration of the first doping element in the activated portion is lower than a doping concentration in the doping portion; Taking the doped portion as a dead layer, performing a first etching process on the first surface to remove the activated portion and form a first velvet surface; At least on one side of the substrate away from the doping portion, a doped polysilicon layer and a silicon glass layer having a second doping element are sequentially formed; Performing a second laser treatment on at least a portion of the silicon glass layer to form a porous portion; Using the remaining silicon glass layer as a protective layer, at least the second surface is subjected to a second etching process to remove the loose portion and the doped polysilicon layer directly opposite to the loose portion, and to form a second velvet surface; The first doping element and the second doping element are of different types, and the first laser treatment and the second laser treatment use different types of lasers.

2. The method for manufacturing a photovoltaic cell according to claim 1, characterized in that: The first surface and the second surface are both third velvet surfaces; after forming the first velvet surface and before forming the doped polysilicon layer, the method further comprises: Polishing the second surface to form a polished surface; The step of forming the doped polysilicon layer and the silicon glass layer includes: forming the doped polysilicon layer on the polishing surface, and forming the silicon glass layer on a side of the doped polysilicon layer away from the polishing surface.

3. The method for manufacturing a photovoltaic cell according to claim 2, characterized in that: After forming the first suede surface and before forming the polishing surface, the method further comprises: At least performing oxidation treatment on the first surface to form a first diffusion barrier layer on the doped portion, and forming a second diffusion barrier layer on the first velvet surface; The step of forming the doped polysilicon layer and the silicon glass layer further includes: forming the doped polysilicon layer on both the first resistance expansion layer and the second resistance expansion layer, and forming the silicon glass layer on a side of the doped polysilicon layer away from the first resistance expansion layer and the second resistance expansion layer.

4. The method for manufacturing a photovoltaic cell according to claim 2, characterized in that: After forming the first suede surface and before forming the polishing surface, the method further comprises: At least performing oxidation treatment on the first surface to form a first diffusion barrier layer on the doped portion, and forming a second diffusion barrier layer on the first velvet surface; The surface jointly formed by the first resistance-expansion layer and the second resistance-expansion layer includes an edge area and a central area surrounded by the edge area, and the step of forming the doped polysilicon layer and the silicon glass layer also includes: forming the doped polysilicon layer on the edge area, and forming the silicon glass layer on a side of the doped polysilicon layer away from the edge area.

5. The method for manufacturing a photovoltaic cell according to claim 3 or 4, characterized in that: The first surface includes a first laser area and a first non-laser area alternately arranged along a first direction, and the second surface includes a second laser area and a second non-laser area alternately arranged along the first direction; The step of performing the first laser treatment on a portion of the doped layer comprises: performing the first laser treatment on the doped layer located in the first laser region to form the activated portion located in the first laser region; The step of performing the second laser treatment on at least a portion of the silicon glass layer includes: performing the second laser treatment on the silicon glass layer located in the second laser region to form the loose portion located in the second laser region.

6. The method for manufacturing a photovoltaic cell according to claim 5, characterized in that: The orthographic projection area of ​​the first laser zone on the substrate is different from the orthographic projection area of ​​the second laser zone on the substrate, and / or the orthographic projection of the first laser zone on the substrate and the orthographic projection of the second laser zone on the substrate at least partially overlap or do not overlap.

7. The method for manufacturing a photovoltaic cell according to claim 5, characterized in that: The step of performing the second etching process on at least the second surface comprises: Etching the first surface using a second chain hydrofluoric acid process to remove the silicon glass layer located on the first surface; The first surface and the second surface are etched by a second texturing process to remove the doped polysilicon layer, the first resistance diffusion layer and the second resistance diffusion layer located on the first surface to expose the first texture surface and the doped part, and to remove the loose part and the doped polysilicon layer located in the second laser area to form the second texture surface.

8. The method for manufacturing a photovoltaic cell according to claim 7, characterized in that: After performing the second texturing process, the method further comprises: The second surface is cleaned by an acid washing process to remove the silicon glass layer located in the second non-laser area to expose the doped polysilicon layer located in the second non-laser area.

9. The method for manufacturing a photovoltaic cell according to claim 1, characterized in that: The step of performing the first etching process on the first surface includes: The first surface is etched using a first texturing process to remove the activated portion and form the first texturing surface.

10. The method for manufacturing a photovoltaic cell according to claim 9, characterized in that: In the step of performing the first laser treatment, an oxide layer is formed on the doped layer; In the step of performing the first etching treatment on the first surface, before etching the first surface with the first texturing process, the step further includes etching the first surface with a first chain hydrofluoric acid process to remove the oxide layer.

11. The method for manufacturing a photovoltaic cell according to claim 1, characterized in that: The first laser treatment uses red nano laser, green nano laser or purple nano laser, and the second laser treatment uses purple laser, green laser, green flying laser or purple flying laser.

12. A photovoltaic cell, characterized in that: The photovoltaic cell is manufactured by the method for manufacturing a photovoltaic cell according to any one of claims 1 to 11.

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