Photovoltaic cell and method for manufacturing the same

Abstract

Embodiments of the present disclosure relate to the field of photovoltaics, and provide a photovoltaic cell and a manufacturing method thereof. The manufacturing method includes: providing a substrate having opposite first and second surfaces; doping at least the first surface to form a doped layer having a first doping element; performing a first laser treatment on a part of the doped layer to form an activated portion, and the remaining doped layer being a doped portion; using the remaining doped layer as a dead layer to perform a first etching treatment on the first surface to remove the activated portion and form a first textured surface; 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 doped portion; performing a second laser treatment on at least a part of the silicon glass layer to form a porous portion; using the remaining silicon glass layer as a protective layer to perform a second etching treatment on at least the second surface to remove the porous portion and the doped polysilicon layer opposite to the porous portion, and form a second textured surface; the laser types used in the first laser treatment and the second laser treatment are different, which is at least beneficial to simplifying the manufacturing process.

Description

Technical Field

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

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

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

[0004] However, the photoelectric conversion efficiencies of photovoltaic cells formed by different manufacturing methods are different, 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] Embodiments of the present disclosure provide a photovoltaic cell and a manufacturing method thereof, which are at least conducive to 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, a manufacturing method of a photovoltaic cell is provided, including: providing a substrate having opposite first and second surfaces; doping at least the first surface to form a doped layer having a first doping element; performing a first laser treatment on a part of the doped layer to form an activation part, and the remaining doped layer as a doping part, wherein the doping concentration of the first doping element in the activation part is lower than that in the doping part; using the doping part as a dead layer, performing a first etching treatment on the first surface to remove the activation part and form a first textured surface; sequentially forming a doped polysilicon layer having a second doping element and a silicon glass layer on at least one side of the substrate away from the doping part; performing a second laser treatment on at least a part of the silicon glass layer to form a loose part; using the remaining silicon glass layer as a protective layer, performing a second etching treatment on at least the second surface to remove the loose part and the doped polysilicon layer opposite to the loose part, and form a second textured surface; wherein the types of the first doping element and the second doping element are different, and the types of lasers used in the first laser treatment and the second laser treatment are different.

[0007] In some embodiments, both the first surface and the second surface are third suede surfaces; after forming the first suede surface and before forming the doped polysilicon layer, the method further 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 a side of the doped polysilicon layer away from the polished surface.

[0008] In some embodiments, after forming the first suede surface and before forming the polished surface, the method further includes: oxidizing at least the first surface to form a first diffusion barrier layer on the doped portion and a second diffusion barrier layer on the first suede surface; the steps of forming the doped polysilicon layer and the silicon glass layer further include: forming the doped polysilicon layer on both the first diffusion barrier layer and the second diffusion barrier layer, and forming the silicon glass layer on a side of the doped polysilicon layer away from the first diffusion barrier layer and the second diffusion barrier layer.

[0009] In some embodiments, after forming the first suede surface and before forming the polished surface, the method further includes: oxidizing at least the first surface to form a first diffusion barrier layer on the doped portion and a second diffusion barrier layer on the first suede surface; a surface formed by the first diffusion barrier layer and the second diffusion barrier layer together includes an edge region and a central region surrounded by the edge region; the steps of forming the doped polysilicon layer and the silicon glass layer further include: forming the doped polysilicon layer on the edge region, and forming the silicon glass layer on a side of the doped polysilicon layer away from the edge region.

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

[0011] In some embodiments, a positive projection area of the first laser regions on the substrate is different from a positive projection area of the second laser regions on the substrate, and / or, a positive projection of the first laser regions on the substrate and a positive projection of the second laser regions on the substrate at least partially overlap or do not overlap.

[0012] In some embodiments, the step of performing the second etching process 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 diffusion barrier layer, and the second diffusion barrier layer located on the first surface, so as to expose the first textured surface and the doped portion, and removing the loose portion and the doped polysilicon layer located in the second laser region, and forming the second textured surface.

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

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

[0015] In some embodiments, during the step of performing the first laser treatment, an oxide layer is formed on the doped layer; during the step of performing the first etching process on the first surface, before etching the first surface using the first texturing process, it further 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 laser, green laser, or purple laser, and the second laser treatment uses purple skin laser, green skin laser, green fly laser, or purple fly laser.

[0017] According to some embodiments of the present disclosure, on the other hand, the present disclosure also provides a photovoltaic cell, including: a photovoltaic cell formed according to the manufacturing method described in any one of the above.

[0018] The technical solution provided by the embodiments of the present disclosure has at least the following advantages:

[0019] On the one hand, the first laser treatment is used to activate the partially doped layer, so that the doping concentration of the first doping element in the partially doped layer is reduced, and the orderliness of the lattice in the partially doped layer is improved, so that the partially doped layer is transformed into an activation part, and the remaining doped layer serves as a doped part. In other words, compared with the doped part, the doping concentration of the doping element in the activation part is lower, making the overall orderliness of the lattice in the activation part stronger. Therefore, under the same etching conditions, the activation part is more easily etched. On this basis, when the first surface is subsequently subjected to the first etching treatment, the etching rate of the activation part with a lower doping concentration of the first doping element by the first etching treatment is much higher than that of the doped part. Thus, without the need for an additional mask, using the doped part as a dead layer, the activation part can be removed to form the first textured surface, which is beneficial to simplifying the manufacturing process of the photovoltaic cell. In addition, compared with using the laser opening process to remove the partially doped layer to form a selective emitter structure in which the doped layer remains only in some areas of the first surface, the combination of the first laser treatment and the first etching treatment is beneficial to reducing the laser damage to the first surface caused by the laser, thus helping to reduce the surface defect state density of the first surface and improve the photoelectric conversion efficiency of the finally formed photovoltaic cell. Moreover, forming a selective emitter structure in which the doped layer remains only in some areas of the first surface, that is, the doped part, is beneficial 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.

[0020] On the other hand, the second laser treatment is used to modify a part of the silicon glass layer into a porous part, so that the degree of porosity of the porous part is higher than that of the remaining silicon glass layer. On this basis, when at least the second surface is subsequently subjected to the second etching treatment, the etching rate of the porous part with a higher degree of porosity by the second etching treatment is much higher than that of the remaining silicon glass layer. Thus, without the need for an additional mask, using the remaining silicon glass layer as a protective layer, the porous part and the doped polysilicon layer opposite to the porous part can be removed to form the second textured surface, which is beneficial to simplifying the manufacturing process of the photovoltaic cell. Moreover, removing the doped polysilicon layer opposite to the porous part is beneficial to avoiding the parasitic absorption of light by the removed part of the doped polysilicon layer. Description of the Drawings

[0021] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplary illustrations do not limit the embodiments unless otherwise stated. The figures in the drawings do not constitute a scale limitation; in order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or in the traditional technology, the drawings required to be used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0022] Figure 1 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;

[0023] Figure 2 Schematic diagram of a partial cross-sectional structure formed after doping treatment is performed on at least the first surface in a method for manufacturing a photovoltaic cell according to an embodiment of the present disclosure;

[0024] Figure 3 Schematic diagram of a partial cross-sectional structure formed after first laser treatment is performed in a method for manufacturing a photovoltaic cell according to an embodiment of the present disclosure;

[0025] Figure 4 Schematic diagram of a partial cross-sectional structure formed after first etching treatment is performed in a method for manufacturing a photovoltaic cell according to an embodiment of the present disclosure;

[0026] Figure 5 Schematic diagram of a partial cross-sectional structure formed after oxidation treatment is performed on at least the first surface in a method for manufacturing a photovoltaic cell according to an embodiment of the present disclosure;

[0027] Figure 6 It is Figure 5 Schematic diagram of a partial cross-sectional structure formed after polishing treatment is performed on the second surface based on the structure shown;

[0028] Figure 7 It is Figure 6 Schematic diagram of a partial cross-sectional structure formed with a doped polysilicon layer and a silicon glass layer based on the structure shown;

[0029] Figure 8 Schematic diagram of a partial cross-sectional structure formed after second laser treatment is performed in a method for manufacturing a photovoltaic cell according to an embodiment of the present disclosure;

[0030] Figure 9 It is Figure 8 Schematic diagram of a partial cross-sectional structure formed after etching the first surface based on the structure shown;

[0031] Figure 10 It is Figure 9 Schematic diagram of a partial cross-sectional structure formed after texturing the first surface and the second surface based on the structure shown;

[0032] Figure 11 It is Figure 10 Schematic diagram of a partial cross-sectional structure formed after cleaning the second surface based on the structure shown.

[0033] Explanation of reference numerals:

[0034] 100. Substrate; 110. First surface; 120. Second surface; 130. Third textured surface; 140. First laser region; 150. First non-laser region; 160. Second laser region; 170. Second non-laser region; 101. Doped layer; 111. Activated portion; 121. Doped portion; 102. Doped polysilicon layer; 103. Silicon glass layer; 113. Loose portion; 104. First groove; 114. First textured surface; 105. Second groove; 115. Second textured surface; 116. First diffusion barrier layer; 126. Second diffusion barrier layer; 136. Third diffusion barrier layer; 108. Second doped layer. Detailed implementation manners

[0035] 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.

[0036] The present disclosure provides a photovoltaic cell and a manufacturing method thereof. In the manufacturing method, on the one hand, the 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, so as to improve the orderliness of the lattice in this part of the doped layer. In other words, compared with the doped portion, the doping concentration of the doping element in the activated portion is lower, so that the overall orderliness of the lattice in the activated portion is stronger. Therefore, under the same etching conditions, the activated portion is more easily etched. On this basis, when the first surface is subjected to the first etching treatment subsequently, the etching rate of the first etching treatment on the activated portion with a lower doping concentration of the first doping element is much higher than that of the doped portion. Thus, without the need to additionally provide a mask, using the doped portion as a dead layer, the activated portion can be removed and the first textured surface can be formed, which is beneficial to simplifying the manufacturing process of the photovoltaic cell. In addition, compared with using a laser opening process to remove a part of the doped layer, with the combined action of the first laser treatment and the first etching treatment, it is beneficial to reduce the laser damage caused by the laser to the first surface, thereby being beneficial to reducing the surface defect state density of the first surface, so as to improve the photoelectric conversion efficiency of the finally formed photovoltaic cell. Moreover, forming a selective emitter structure in which only a part of the first surface retains the doped portion is beneficial to reducing the contact resistance between the subsequently formed electrode and the doped portion, and reducing the probability of carrier recombination in other regions of the first surface. On the other hand, the second laser treatment is used to modify a part of the silicon glass layer into a loose portion. On this basis, when at least the second surface is subjected to the second etching treatment subsequently, the etching rate of the second etching treatment on the loose portion with a higher degree of porosity is much higher than that of the remaining silicon glass layer. Thus, without the need to additionally provide a mask, using the remaining silicon glass layer as a protective layer, the loose portion and the doped polysilicon layer opposite to the loose portion can be removed, and the second textured surface can be formed, which is beneficial to simplifying the manufacturing process of the photovoltaic cell. Moreover, removing the doped polysilicon layer opposite to the loose portion is beneficial to avoiding the parasitic absorption of light by this part of the removed doped polysilicon layer.

[0037] In the description of the embodiments of the present disclosure, technical terms such as "first" and "second" are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present disclosure, the meaning of "a plurality of" is more than two, unless otherwise specifically defined.

[0038] Reference to "embodiments" in this text means that the specific features, structures, or characteristics described in connection with the embodiments may be included in at least one embodiment of the present disclosure. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0039] In the description of the embodiments of the present disclosure, the term "and / or" is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: the existence of A, the simultaneous existence of A and B, and the existence of B. In addition, the character " / " in this text generally represents an "or" relationship between the associated objects before and after.

[0040] In the description of the embodiments of the present disclosure, the term "a plurality of" means more than two (including two). Similarly, "a plurality of groups" means more than two groups (including two groups), and "a plurality of pieces" means more than two pieces (including two pieces).

[0041] In the description of the embodiments of the present disclosure, technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. This is only for the convenience of describing the embodiments of the present disclosure and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present disclosure.

[0042] In the description of the embodiments of the present disclosure, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "coupling", "fixing", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may also be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and may be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to specific circumstances.

[0043] In the accompanying drawings corresponding to the embodiments of the present disclosure, for better understanding and description, the thickness and area of the layers are enlarged. When describing a component (such as a layer, film, region, or substrate) being on or on the surface of another component, the component can be "directly" on the surface of the other component, or there can be a third component between the two components. Conversely, when describing a component being on the surface of another component or when the surface of one component forms or is provided with another component, it means there is no third component between the two components. In addition, when describing a component being "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor on a partial edge of the entire surface.

[0044] In the description of the embodiments of the present disclosure, when a certain component "includes" another component, unless otherwise specified, other components are not excluded, and other components may further be included. In addition, when components such as layers, films, regions, or plates are referred to as being "on / at" another component, it can be "directly on" the other component (i.e., on the surface of the other component with no other components between them), or there can be another component between them. In addition, when components such as layers, films, regions, plates, etc. are "directly located on" another component, or when components such as layers, films, regions, plates, etc. are located on the surface of another component, it means that no other components are located between them.

[0045] The terms used in the description of the various embodiments herein are only for describing specific embodiments and are not intended to be limiting. As used in the description of the various embodiments and the appended claims, "the component" is also intended to include the plural form, unless the context clearly indicates otherwise. Among them, the component includes components such as layers, films, regions, or plates.

[0046] The embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. However, those of ordinary skill in the art can understand that in the embodiments of the present disclosure, many technical details are provided for readers to better understand the embodiments of the present disclosure. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions required to be protected by the embodiments of the present disclosure can be implemented.

[0047] 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 It is a schematic diagram of a partial cross-sectional structure corresponding to each step in the method for manufacturing a photovoltaic cell provided by an embodiment of the present disclosure.

[0048] With reference to Figures 1 to 11 , the method for manufacturing a photovoltaic cell at least includes the following steps:

[0049] Step S1: Refer toFigure 1 , Figure 1 This is 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. A substrate 100 is provided, and the substrate 100 has opposite first and second surfaces 110 and 120.

[0050] 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, it may be silicon or germanium. Among them, the elemental semiconductor material may be in a single crystal state, a polycrystalline state, an amorphous state, or a microcrystalline state (a state having both a single crystal state and an amorphous state is called a microcrystalline state). For example, silicon may be at least one of single crystal silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. In other embodiments, the material of the substrate 100 may also be a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, silicon germanide, silicon carbide, gallium arsenide, indium gallium, perovskite, cadmium telluride, copper indium selenide and other materials. Subsequently, an exemplary description will be given with the material of the substrate 100 being silicon.

[0051] Step S2: Refer to Figure 2 , Figure 2 This is a schematic diagram of a partial cross-sectional structure formed after doping at least the first surface in a method for manufacturing a photovoltaic cell according to an embodiment of the present disclosure. At least the first surface 110 is doped to form a doped layer 101 having a first doping element.

[0052] Step S3: Referring to Figure 2 and Figure 3 , Figure 3 This is a schematic diagram of a partial 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. A first laser treatment is performed on a part of the doped layer 101 to form an activated part 111, and the remaining doped layer 101 serves as a doped part 121. The doping concentration of the first doping element in the activated part 111 is lower than that in the doped part 121.

[0053] Step S4: Referring to Figure 3 and Figure 4 , Figure 4 This is a schematic diagram of a partial cross-sectional structure formed after a first etching treatment in a method for manufacturing a photovoltaic cell according to an embodiment of the present disclosure. Using the doped part 121 as a dead layer, a first etching treatment is performed on the first surface 110 to remove the activated part 111 and form a first textured surface 114.

[0054] Step S5: Referring to Figures 4 to 7 , at least a doped polysilicon layer 102 having a second doping element and a silicon glass layer 103 are sequentially formed on the side of the substrate 100 away from the doped part 121.

[0055] It should be noted that Figure 5 is a schematic diagram of a partial cross-sectional structure formed after at least oxidizing the first surface in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 6 is Figure 5 a schematic diagram of a partial cross-sectional structure formed after polishing the second surface on the basis of the structure shown; Figure 7 is Figure 6 a schematic diagram of a partial cross-sectional structure formed with a doped polysilicon layer and a silicon glass layer on the basis of the structure shown.

[0056] Step S6: Refer to Figure 8 , Figure 8 is a schematic diagram of a partial cross-sectional structure formed after performing a second laser treatment in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure. At least part of the silicon glass layer 103 is subjected to the second laser treatment to form a porous part 113.

[0057] Step S7: With reference to 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 treatment to remove the porous part 113 and the doped polysilicon layer 102 opposite to the porous part 113, and a second texture surface 115 is formed.

[0058] Among them, the types of the first doping element and the second doping element are different, and the laser types used in the first laser treatment and the second laser treatment are different.

[0059] It should be noted that Figure 9 is Figure 8 a schematic diagram of a partial cross-sectional structure formed after etching the first surface on the basis of the structure shown; Figure 10 is Figure 9 a schematic diagram of a partial cross-sectional structure formed after texturing the first surface and the second surface on the basis of the structure shown; Figure 11 is Figure 10 a schematic diagram of a partial cross-sectional structure formed after cleaning the second surface on the basis of the structure shown.

[0060] It should be noted that not only are the laser types used in the first laser treatment and the second laser treatment different, but also the objects targeted by the first laser treatment and the second laser treatment are different.

[0061] Specifically, in step S3, the first laser treatment is performed on the partially doped layer 101 to activate the partially doped layer 101, so that the doping concentration of the first doping element in the partially doped layer 101 is reduced, and the orderliness of the lattice in the partially doped layer 101 is improved. As a result, the partially doped layer 101 is transformed into the activation part 111, and the remaining doped layer 101 not targeted by the first laser treatment serves as the doping part 121. In other words, compared with the doping part 121, the doping concentration of the doping element in the activation part 111 is lower, making the overall orderliness of the lattice in the activation part 111 higher. Therefore, under the same etching conditions, the activation part 111 is more easily etched.

[0062] On this basis, in subsequent step S4, when the first etching treatment is performed on the first surface 110, the etching rate of the activation part 111 with a lower doping concentration of the first doping element by the first etching treatment is much higher than that of the doping part 121. Thus, without the need for an additional mask, the activation part 111 can be removed with the doping part 121 as the dead layer to form the first textured surface 114, which is beneficial to simplifying the manufacturing process of the photovoltaic cell. In addition, compared with the method of using a laser to open the film to remove the partially doped layer 101, that is, directly using laser ablation of the partially doped layer 101 to form a selective emitter structure in which the doped layer 101 remains only in some areas of the first surface 110, in the manufacturing method provided by an embodiment of the present disclosure, with the combined action of the first laser treatment and the first etching treatment, it is beneficial to reduce the laser damage to the first surface 110 caused by the laser. 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 beneficial to reducing the surface defect state density of the first surface 110 and improving the photoelectric conversion efficiency of the finally formed photovoltaic cell.

[0063] Moreover, after step S3, a selective emitter structure is formed in which the doped layer 101, that is, the doping part 121, remains only in some areas of the first surface 110, which is beneficial to 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 finally formed photovoltaic cell.

[0064] In step S6, the second laser treatment is performed on at least a part of the silicon glass layer 103 to modify this part of the silicon glass layer 103 into a porous part 113. For example, the degree of porosity of the porous part 113 is higher than that of the remaining silicon glass layer 103. On this basis, when the second etching treatment is performed on at least the second surface 120 in the subsequent step S7, the etching rate of the porous part 113 with a higher degree of porosity by the second etching treatment is much higher than that of the remaining silicon glass layer 103. Thus, without the need for an additional mask, using the remaining silicon glass layer 103 as a protective layer, the porous part 113 and the doped polysilicon layer 102 opposite to the porous part 113 can be removed to form the second textured surface 115, which is beneficial to simplifying the manufacturing process of the photovoltaic cell.

[0065] Moreover, removing the doped polysilicon layer 102 opposite to the porous part 113 helps to avoid the parasitic absorption of light by this part of the removed doped polysilicon layer 102, and the exposed second textured surface 115 can improve the absorption utilization rate of light, which 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 finally formed photovoltaic cell.

[0066] It should be emphasized that the purpose of the first laser treatment in step S3 is to activate a part of the doped layer 101, changing the doping concentration of the first doping element in a part of the doped layer 101 and the lattice order in the part of the doped layer 101, and taking the doped layer 101 with the doping concentration of the first doping element reduced as the activation part 111. In contrast, the purpose of the second laser treatment in step S6 is to modify at least a part of the silicon glass layer 103, changing the degree of porosity of the part of the silicon glass layer 103, and taking the silicon glass layer 103 with the increased degree of porosity as the porous part 113.

[0067] In some cases, the fact that the doping concentration of the doping element in the activation part 111 is lower than that in the doping part 121 means that: taking the surface of the activation part 111 far from the substrate 100 as the first reference surface and the surface of the doping part 121 far from the substrate 100 as the second reference surface, compared with the effective doping concentration of the doping element within a depth of 100 nm from the second reference surface towards the substrate 100 in the doping part 121, the effective doping concentration of the doping element within a depth of 100 nm from the first reference surface towards the substrate 100 in the activation part 111 is lower, making the overall lattice order in the activation part 111 stronger.

[0068] In some examples, the doping concentration of the doping element in the activation part 111 is the first doping concentration, and the doping concentration of the doping element in the doping part 121 is the 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.

[0069] In some examples, the effective doping concentrations in the activation part 111 and the doping part 121 are measured by using ECV (Electrochemical capacitance-voltage profiler) testing. The effective doping concentration of the doping element within a depth of 100 nm from the first reference surface towards the substrate 100 in the activation part 111 is less than 5×10 19 atom / cm 3 , and the effective doping concentration of the doping element within a depth of 100 nm from the second reference surface towards the substrate 100 in the doping part 121 is greater than 5×10 18 atom / cm 3 .

[0070] It should be noted that in the first etching process, treating the doping part 121 and the activation part 111 under the same etching conditions means treating the doping part 121 and the activation part 111 with the same etching solution, and the treatment duration for the doping part 121 and the activation part 111 is the same.

[0071] In some cases, under the same etching solution, the etching depth of the etching solution for the activation part 111 per unit time is much greater than that for the doping part 121. Therefore, the etching rate of the first etching process for the activation part 111 with a lower doping concentration of the first doping element is much higher than that of the doping part.

[0072] In some examples, under the same etching solution, the ratio of the etching depth of the activation part 111 to the etching depth of the doping part 121 per unit time is greater than or equal to 10. In one example, using the same etching solution, the activation part 111 and the doping part 121 are simultaneously etched for about 600 s. The etching depth of the activation part 111 is about 2 μm, while the etching depth of the doping part 121 is about 100 nm. In other words, compared with the activation part 111, the doping part 121 can be regarded as hardly etched. During the first etching process, when the activation part 111 is completely removed and the first suede surface is formed, at least most of the thickness of the doping part 121 is not etched.

[0073] In some cases, the higher degree of porosity of the porous part 113 compared with the remaining silicon glass layer 103 means that: from a microscopic perspective, film bursting can be seen inside the porous part 113. For example, cracks or fragments can be seen inside the porous part 113, and the maximum size of the fragments does not exceed 100 μm. Among them, a scanning electron microscope (SEM) can be used to know the degree of porosity of the porous part 113 from a microscopic perspective.

[0074] The following will detail each step in the method for preparing a photovoltaic cell provided in an embodiment of the present disclosure:

[0075] In some embodiments, the substrate 100 can 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 can be at least one of Group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As); the P-type semiconductor substrate is doped with a P-type element, and the P-type doping element can be at least one of Group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0076] In one example, the doping process performed on at least the first surface 110 in step S2 can be a boron diffusion process, so that at least part of the substrate 100 doped with boron (B) element can be regarded as the doping layer 101, and the doping layer 101 can be regarded as the boron diffusion layer; the material of the doped polysilicon layer 102 in step S4 can be N-type polysilicon, and the material of the silicon glass layer 103 can be phosphosilicate glass.

[0077] In other embodiments, the substrate can 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.

[0078] In some embodiments, the photovoltaic cell is a single-sided cell. In step S1, the first side 110 can be regarded as the front side of the photovoltaic cell, that is, the first side 110 can be used as the light-receiving surface for receiving incident light, and the second side 120 can be used as the backlight surface. In some other embodiments, the photovoltaic cell is a double-sided cell, then both the first side 110 and the second side 120 can be used as the light-receiving surfaces and 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 incident light is weaker than that of the light-receiving surface, so it is defined as the backlight surface. Subsequently, the first side 110 is used as the light-receiving surface and the second side 120 is used as the backlight surface for exemplary illustration.

[0079] In some embodiments, referring to Figure 3 , in step S3, the first laser treatment can use red nano-laser, green nano-laser or purple nano-laser; referring to Figure 8 , in step S6, the second laser treatment can use purple picosecond laser, green picosecond laser, green femtosecond laser or purple femtosecond laser. In this way, by using red nano-laser, green nano-laser or purple nano-laser, the doping concentration of the first doping element in part of the doped layer 101 is reduced, and the doped layer 101 with the reduced doping concentration of the first doping element is used as the activation part 111 to improve the overall orderliness of the lattice in the activation part 111; by using purple picosecond laser, green picosecond laser, green femtosecond laser or purple femtosecond laser, the porosity of part of the silicon glass layer 103 is changed, and the silicon glass layer 103 with increased porosity is used as the porous part 113.

[0080] It should be noted that red nano-laser, green nano-laser or purple nano-laser all belong to nanosecond lasers, that is, the laser used in the first laser treatment can be a short-pulse laser; purple picosecond laser and green picosecond laser both belong to picosecond lasers, and green femtosecond laser or purple femtosecond laser both belong to femtosecond lasers. Picosecond lasers and femtosecond lasers are both ultra-short pulse lasers, that is, the laser used in the second laser treatment can be an ultra-short 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.

[0081] 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.

[0082] In some examples, the wavelength ranges of the green 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 492 nm to 577 nm. For example, they can be 493 nm, 495 nm, 496 nm, 500 nm, 502 nm, 505 nm, 508 nm, 510 nm, 513 nm, 515 nm, 516 nm, 520 nm, 522 nm, 525 nm, 528 nm, 530 nm, 532 nm, 535 nm, 538 nm, 540 nm, 542 nm, 545 nm, 548 nm, 550 nm, 552 nm, 555 nm, 558 nm, 560 nm, 562 nm, 565 nm, 568 nm, 570 nm, 572 nm, 575 nm or 578 nm, etc.

[0083] In some examples, the wavelength ranges of the purple laser used in the first laser treatment, and the purple skin laser and purple flying laser used in the second laser treatment can all be 200 nm to 400 nm. For example, they can be 205 nm, 210 nm, 215 nm, 220 nm, 225 nm, 230 nm, 235 nm, 240 nm, 245 nm, 250 nm, 255 nm, 260 nm, 265 nm, 270 nm, 275 nm, 280 nm, 285 nm, 290 nm, 295 nm, 300 nm, 305 nm, 310 nm, 315 nm, 320 nm, 325 nm, 330 nm, 335 nm, 340 nm, 345 nm, 350 nm, 355 nm, 360 nm, 365 nm, 370 nm, 375 nm, 380 nm, 385 nm, 390 nm or 395 nm, etc.

[0084] In some embodiments, with reference to Figure 3 and Figure 4 , the step of forming the first matte surface 114 in step S4 may include: forming a first groove 104 with the bottom surface being the first matte surface 114.

[0085] It should be noted that the etching rate of the first etching process for the activation part 111 is much higher than that for the doping part 121. On this basis, in step S4, with the doping part 121 as the barrier layer, not only the activation part 111 will be removed, but also the first surface 110 exposed after the activation part 111 is removed can be further etched to form the first groove 104. Relative to the substrate 100 facing the doping part 121, the first groove 104 further sinks into the substrate 100, that is, it sinks in the direction from the first surface 110 to the second surface 120. In other words, the first surface 110 includes a first laser region 140 and a first non-laser region 150 arranged alternately along the first direction X. The doping part 121 not etched by the first etching process is located in the first non-laser region 150, and the first groove 104 is located in the first laser region 140. After step S4 is performed, the surface of the substrate 100 in the first non-laser region 150 is higher than the surface of the substrate 100 in the first laser region 140 to form the first groove 104 in the first laser region 140. In addition, based on the further etching of the substrate 100 facing the activation part 111 by the first etching process, at least the bottom surface of the first groove 104 can have a first matte surface 114.

[0086] In this way, on the one hand, the first matte surface 114 not only reduces the reflectivity of the bottom surface of the first groove 104, but also forms a light trap to enhance the absorption effect of the first matte surface 114 on incident light. On the other hand, further relying on the characteristic that the first groove 104 sinks 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 and utilization rate of the incident light by the first groove 104. Therefore, with the combined cooperation of the first groove 104 and the first matte surface 114, it is beneficial to increase the photoelectric conversion efficiency of the photovoltaic cell.

[0087] It should be noted that based on the regulation of the concentration of the etching solution used in the first etching process and / or the processing duration of the first etching process, it can be controlled whether the first etching process further etches the first surface 110 exposed after the activation part 111 is removed, that is, it can be controlled whether to further form the first groove 104 on the first laser region 140 of the substrate 100; further, the etching degree of the substrate 100 facing the activation part 111 by the first etching process can also be controlled, that is, the depth of the formed first groove 104 can be controlled.

[0088] In some examples, the processing duration of the first etching process can be 600s to 750s, for example, it can be 610s, 620s, 630s, 640s, 650s, 660s, 670s, 680s, 690s, 700s, 710s, 720s, 730s or 740s, etc.

[0089] In some examples, the depth of the first groove 104 can be 2.5 μm to 4 μm, for example, it can be 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, etc.

[0090] It should be noted that Figure 4 taking the example that the doped portion 121 is reserved 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 practical applications, the surfaces of the first non-laser area and the first laser area of the substrate can be flush.

[0091] In some embodiments, with reference to Figures 8 to 11 , the step of forming the second matte surface 115 in step S7 may include: forming a second groove 105 with the bottom surface being the second matte surface 115.

[0092] It should be noted that the etching rate of the second etching process for the loose portion 113 is much higher than that for the remaining silicon glass layer 103. On this basis, in step S7, using the remaining silicon glass layer 103 as a protective layer, not only the loose portion 113 can be removed, but also the second surface 120 exposed after the removal of the loose portion 113 can be further etched to form the second groove 105. Relative to the substrate 100 opposite to the loose portion 113, the second groove 105 further sinks into the substrate 100, that is, it sinks in the direction where the second surface 120 points to the first surface 110. In other words, the second surface 120 includes second laser areas 160 and second non-laser areas 170 arranged alternately 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 performing step S7, the surface of the substrate 100 in the second non-laser area 170 is higher than the surface of the substrate 100 in the second laser area 160 to form the second groove 105 in the second laser area 160. In addition, based on the further etching of the substrate 100 opposite to the loose portion 113 by the second etching process, at least the bottom surface of the second groove 105 can have the second matte surface 115.

[0093] In this way, on the one hand, the second matte surface 115 not only reduces the reflectivity of the bottom surface of the second groove 105, but also can form a light trap to enhance the absorption effect of the second matte surface 115 on incident light. On the other hand, further relying on the characteristic that the second groove 105 sinks 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 for incident light. Therefore, with the combined cooperation of the second groove 105 and the second matte surface 115, it is beneficial to increase the photoelectric conversion efficiency of the photovoltaic cell.

[0094] It should be noted that, based on the regulation of the concentration of the etching solution used in the second etching process and / or the processing duration of the second etching process, it can be controlled whether the second etching process further etches the second surface 120 exposed after the removal of the loose part 113 after removing the loose part 113, that is, it can be controlled whether to further form the second groove 105 on the second laser region 160 of the substrate 100; further, it can also control the etching degree of the substrate 100 opposite to the loose part 113 in the second etching process, that is, control the depth of the formed second groove 105.

[0095] In some examples, the processing duration of the second etching process can be 600 s to 750 s, for example, it can be 610 s, 620 s, 630 s, 640 s, 650 s, 660 s, 670 s, 680 s, 690 s, 700 s, 710 s, 720 s, 730 s or 740 s, etc.

[0096] In some examples, the depth of the second groove 105 can be 2 μm to 3 μm, for example, it can be 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, etc.

[0097] It should be noted that Figure 10 in the example where the silicon glass layer 103 is retained on the second non-laser region 170 of the substrate 100 and the second groove 105 is formed on the second laser region 160 of the substrate 100, in practical applications, the surfaces of the second non-laser region and the second laser region of the substrate can be flush.

[0098] In addition, on the basis of forming the first groove 104 with the first matte surface 114 on the bottom surface in step S4, the second groove 105 with the second matte surface 115 on the bottom surface can be further formed in step S7. In other words, the first groove 104 on the first surface 110 and the second groove 105 on the second surface 120 can exist simultaneously in the finally formed photovoltaic cell. In this way, it is beneficial to improve the absorption utilization rate of incident light on both the first surface 110 and the second surface 120, thereby being beneficial to improving the bifaciality of the photovoltaic cell.

[0099] In practical applications, when forming the first groove with the first suede surface as the bottom surface in step S4, a second suede surface flush with the substrate surface facing the remaining silicon glass layer can be formed in step S7; or, when forming the first suede surface flush with the substrate surface facing the doping portion in step S4, a second groove with the second suede surface as the bottom surface can be formed in step S7; or, when forming the first suede surface flush with the substrate surface facing the doping portion in step S4, a second suede 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 "flush" means that the height difference between the two surfaces is extremely low, even zero.

[0100] In some embodiments, with reference to 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; with reference to Figure 3 and Figure 4 , the step of performing the first etching treatment on the first surface 110 in step S4 may include: etching the first surface 110 using the first chain hydrofluoric acid process to remove the oxide layer; then etching the first surface 110 using the first texturing process to remove the activation portion 111 and form the first suede surface 114.

[0101] It should be noted that based on the effect of the laser used in the first laser treatment on the doping layer 101, the surface of a part of the thickness of the doping layer 101 away from the substrate 100 is easily thermally oxidized, so an oxide layer is formed on the doping layer 101. In some examples, the material of the oxide layer can be silicon oxide.

[0102] On this basis, the first etching treatment includes two successive etching processes. First, the first surface 110 is etched using the first chain hydrofluoric acid process, and then the first surface 110 is etched using the first texturing process, which is beneficial to specifically remove the oxide layer and the activation portion 111 respectively, and is beneficial to improving the etching accuracy of the first etching treatment. In some examples, in step S4, it is finally necessary to form the first groove 104 with the first suede surface 114 as the bottom surface. Designing the first etching treatment to include two successive etching processes is beneficial to forming a good step morphology on the first surface 110, that is, forming the first groove 104 with a controllable surface morphology. For example, it is beneficial to form the first groove 104 with almost the same depth in each region.

[0103] In other embodiments, the step of performing the first etching treatment on the first surface includes: etching the first surface using the first texturing process to remove the activation portion and form the first suede surface. In other words, the first etching treatment can be the first texturing process, that is, directly using the first texturing process to remove the oxide layer and the activation portion and form the first suede surface.

[0104] In some embodiments, the first surface 110 includes a first laser region 140 and a first non-laser region 150 arranged alternately along the first direction X, and the second surface 120 includes a second laser region 160 and a second non-laser region 170 arranged alternately along the first direction X; after performing step S4 to form the first textured surface 114, the first surface 110 located in the first non-laser region 150 remains the third textured surface 130 (refer to Figure 1 ), the third textured surface 130 has a third pyramid structure, the first textured surface 114 has a first pyramid structure, and the size of the third pyramid structure is larger than that of the first pyramid structure.

[0105] It should be noted that the entire first surface 110 of the substrate 100 passed through in step S1 can be the third textured surface 130. After performing steps S2 to S4, due to the etching effect of the first etching process on the substrate 100, that is, the further etching of the third textured surface 130 located in the first laser region 140, the third textured surface 130 located in the first laser region 140 is transformed into the first textured surface 114. In this way, it is beneficial to improve the light trapping effect of the first textured surface 114 by means of the first pyramid structure with a smaller size.

[0106] In some embodiments, refer to Figure 1 and Figure 2 , both the first surface 110 and the second surface 120 provided in step S1 can be the third textured surface 130; in combination with reference to Figures 4 to 6 , after forming the first textured 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; in combination with reference to 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 polished surface, and forming the silicon glass layer 103 on the side of the doped polysilicon layer 102 away from the polished surface.

[0107] It should be noted that the flatness of the polished surface is high. Forming the doped polysilicon layer 102 on the polished surface is more conducive to improving the uniformity of the doped polysilicon layer 102, that is, forming a doped polysilicon layer 102 with almost the same 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, and thus beneficial to improving the photoelectric conversion efficiency of the finally formed photovoltaic cell.

[0108] In some cases, refer to Figure 2 , in the step of doping at least the first surface 110 in step S2, the second surface 120 is also doped to form a second doped layer 108 with a first doping element on the second surface 120, and the doped layer 101 formed on the first surface 110 can be regarded as the first doped layer; in combination with reference to Figures 4 to 6In the step of polishing the second side 120, the second doping layer 108 is removed.

[0109] In some cases, referring to Figure 5 , after forming the first textured surface 114 in step S4 and before forming the polishing surface, the manufacturing method may further include: oxidizing at least the first side 110 to form a first diffusion barrier layer 116 on the doped portion 121 and a second diffusion barrier layer 126 on the first textured surface 114.

[0110] It should be noted that the first diffusion barrier layer 116 is formed by oxidizing a part of the thickness of the doped portion 121. In some examples, the material of the first diffusion barrier layer 116 may be borosilicate glass; the second diffusion barrier layer 126 is formed by oxidizing a part of the thickness of the substrate 100. In some examples, the material of the second diffusion barrier layer 126 may be silicon oxide.

[0111] In addition, in the step of oxidizing at least the first side 110, the doping elements in the doped portion 121 will be promoted to further diffuse into the substrate 100, which is beneficial to deepening the junction depth of the doped portion 121, so as to increase the junction depth of the PN junction formed by the doped portion 121 and the substrate 100. Moreover, the doping concentration of the doping elements in the doped portion 121 can be slightly reduced to reduce the density of defect states at the contact between the subsequently formed electrode and the doped portion 121, so as to improve the contact performance between the electrode and the doped portion 121. On this basis, referring to Figure 7 , the steps of forming the doped polysilicon layer 102 and the silicon glass layer 103 in step S5 may further include: forming the doped polysilicon layer 102 on both the first diffusion barrier layer 116 and the second diffusion barrier layer 126, and forming the silicon glass layer 103 on the side of the doped polysilicon layer 102 away from the first diffusion barrier layer 116 and the second diffusion barrier layer 126. It should be noted that in the steps of forming the doped polysilicon layer 102 and the silicon glass layer 103, affected by high-temperature diffusion, the second doping element will gradually diffuse into the doped polysilicon layer 102. In this way, on the one hand, the first diffusion barrier layer 116 located on the doped portion 121 is beneficial to blocking the further diffusion of the second doping element into the doped portion 121, avoiding the loss of the second doping element and avoiding the modification of the doped portion 121 affected by the diffusion of the second doping element, such as avoiding the doped portion 121 changing from P-type to N-type; on the other hand, the second diffusion barrier layer 126 located on the first textured surface 114 is beneficial to blocking the further diffusion of the second doping element into the substrate 100, such as the first laser region 140, avoiding the loss of the second doping element.

[0112] In other cases, after the first matte surface is formed in step S4 and before the polishing surface is formed, the manufacturing method may further include: at least oxidizing the first surface to form a first diffusion barrier layer on the doped portion and a second diffusion barrier layer on the first matte surface; the surface formed by the first diffusion barrier layer and the second diffusion barrier layer together includes an edge region and a central region surrounded by the edge region, and the steps of forming the doped polysilicon layer and the silicon glass layer may further include: forming the doped polysilicon layer on the edge region, and forming the silicon glass layer on one side of the doped polysilicon layer away from the edge region. In other words, in step S5, in the steps of forming the doped polysilicon layer and the silicon glass layer on the second surface, due to the plating-around phenomenon, the doped polysilicon layer and the silicon glass layer will also be sequentially formed on the edge region of the surface formed by the first diffusion barrier layer and the second diffusion barrier layer together. Thus, the first diffusion barrier layer located on the doped portion is also beneficial to blocking the further diffusion of the second doping element into the doped portion, and the second diffusion barrier layer located on the first matte surface is also beneficial to blocking the further diffusion of the second doping element into the substrate.

[0113] In some examples, referring to Figure 2 , a second doped layer 108 having a first doping element is further formed on the second surface 120 in step S2; based on this, referring 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 diffusion barrier layer 136 on a side of the second doped layer 108 away from the second surface 120. It should be noted that the second diffusion barrier layer 126 and the third diffusion barrier layer 136 can be formed synchronously through the same oxidation treatment step. In some examples, the material of the third diffusion barrier layer 136 and the material of the second diffusion barrier 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 diffusion barrier layer 136 is removed.

[0114] In some cases, in the oxidation treatment step, the temperature is controlled at 1000°C to 1100°C, for example, it can be 1010°C, 1020°C, 1030°C, 1040°C, 1050°C, 1060°C, 1070°C, 1080°C or 1090°C, etc.

[0115] In some cases, referring to Figure 7, the steps 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 performing 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 performing a high-temperature treatment on the semiconductor layer and the doping source layer 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 the doping source layer into the silicon glass layer 103. In other cases, the steps 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 performing step S4. Due to the plating phenomenon, a semiconductor layer will also be formed on the edge region of the surface jointly formed by the first diffusion barrier layer and the second diffusion barrier layer. 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 performing a high-temperature treatment on the semiconductor layer and the doping source layer to promote the diffusion of the second doping element into the semiconductor layer, thereby transforming the semiconductor layer into the doped polysilicon layer and the doping source layer into the silicon glass layer.

[0116] In some examples, the material of the semiconductor layer may be amorphous silicon, and the high-temperature treatment step also promotes the crystallization of the amorphous silicon to transform it into polysilicon; in other examples, the material of the semiconductor layer may be polysilicon.

[0117] In some embodiments, referring to Figure 1 , the first surface 110 includes a first laser region 140 and a first non-laser region 150 alternately arranged along the first direction X, and the second surface 120 includes a second laser region 160 and a second non-laser region 170 alternately arranged along the first direction X. Referring to Figure 3 , the step of performing the first laser treatment on part of the doped layer 101 in step S3 may include: performing the first laser treatment on the doped layer 101 located in the first laser region 140 to form an activation portion 111 located in the first laser region 140; referring to Figure 8 , the step of performing the second laser treatment on at least part of the silicon glass layer 103 may include: performing the second laser treatment on the silicon glass layer 103 located in the second laser region 160 to form a porous portion 113 located in the second laser region 160.

[0118] In this way, in the finally formed photovoltaic cell, the doped portion 121 is only located in the first non-laser region 150. The doped portion 121 can be regarded as a selective emitter located on the first surface 110, which is beneficial to ensuring good current collection efficiency of the subsequent electrode based on the doped portion 121 while avoiding the first laser region 140 being covered by the doped layer 101, thereby avoiding the parasitic absorption of the doped layer 101 to the light incident on the first laser region 140, improving the utilization rate of the first surface 110 for the incident light, and improving the photoelectric conversion efficiency of the photovoltaic cell.

[0119] In some cases, with reference to Figure 7 , in step S5 of forming the doped polysilicon layer 102 having the second doping element, a tunneling layer (not shown in the figure) is further 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, in step S7, the second etching process also removes the tunneling layer opposite to the loose portion 113.

[0120] In this way, in the finally formed photovoltaic cell, the tunneling layer and the doped polysilicon layer 102 are only located in the second non-laser region 170. The tunneling layer and the doped polysilicon layer 102 form a selective passivation contact structure on the second surface 120, which is beneficial to ensuring a good passivation effect of the tunneling layer and the doped polysilicon layer 102 on the second surface 120 while avoiding the second laser region 160 being covered by the doped polysilicon layer 102, thereby avoiding the parasitic absorption of the doped polysilicon layer 102 to the light incident on the second laser region 160, improving the utilization rate of the second surface 120 for incident light, and improving the photoelectric conversion efficiency of the photovoltaic cell.

[0121] In some embodiments, with reference to Figure 10 or Figure 11 , both the first non-laser region 150 and the second non-laser region 170 at least include the region where the positive projection of the electrode (not shown in the figure) on the substrate 100 is located. The region on the first surface 110 other than the first non-laser region 150 is the first laser region 140, and the region on the second surface 120 other than the second non-laser region 170 is the second laser region 160. Among them, in order to ensure that the film layer contacted by the electrode has a relatively high doping concentration or the regions contacted by the electrode are all high-concentration regions, thereby reducing the contact resistance, generally, the positive projection area of the first non-laser region 150 and the second non-laser region 170 is greater than or equal to the positive projection area of the electrode. In other words, the positive projection area of the electrode on the substrate 100 is smaller than the area of the first non-laser region or the second non-laser region, and the positive projection position must be within the first non-laser region or the second non-laser region.

[0122] It should be noted that the number of laser regions and the number of non-laser regions can both be multiple, and the laser regions and the non-laser regions are alternately arranged in a fixed direction. In other words, a laser region can be located in the interval between adjacent laser regions, and a non-laser region can also be located in the interval between adjacent laser regions. The laser regions include the first laser region 140 and the second laser region 160, and the non-laser regions include the first non-laser region 150 and the second non-laser region 170.

[0123] In some embodiments, with reference to Figure 10 or Figure 11, the orthographic projection area of the first laser region 140 on the substrate 100 and the orthographic projection area of the second laser region 160 on the substrate 100 may be different. It should be noted that due to different types of photovoltaic cells, different light absorption rates of the first surface 110 and the second surface 120, and different size designs of the subsequent formed doped portion 121 and doped polysilicon layer 102, the orthographic projection area of the first laser region 140 on the first surface 110 and the orthographic projection area of the second laser region 160 on the first surface 110 can be different, that is, the sizes of the first laser region 140 and the second laser region 160 are different. Thus, the preparation method provided by an embodiment of the present disclosure is applicable to various photovoltaic cells.

[0124] In one example, the orthographic projection area of the first laser region on the first surface may be less than or equal to the orthographic projection area of the second laser region on the first surface; in another example, the orthographic projection area of the first laser region on the first surface may be greater than the orthographic projection area of the second laser region on the first surface. It should be noted that the orthographic projection areas of multiple first laser regions on the first surface may be the same or different and can be designed according to actual needs; the orthographic projection areas of multiple second laser regions on the first surface may be the same or different and can also be designed according to actual needs.

[0125] In other embodiments, the orthographic projection of the first laser region on the first surface does not overlap with the orthographic projection of the second laser region on the first surface. In other words, it is avoided that the first laser region and the second laser region face each other along the second direction, and the second direction is the thickness direction of the photovoltaic cell. Thus, it is avoided that the laser of the first laser treatment acting on the first surface in step S3 and the laser of the second laser treatment acting on the second surface in step S6 repeatedly process the same part in the substrate, so as to avoid local repeated overheating and damage in the substrate, thereby being beneficial to improving the electrical performance of the finally formed photovoltaic cell.

[0126] In one example, the first laser region may face the second non-laser region along the second direction, that is, the orthographic projection of the first laser region on the first surface coincides with the orthographic projection of the second non-laser region on the first surface; the first non-laser region may face the second laser region along the second direction, that is, the orthographic projection of the first non-laser region on the first surface coincides with the orthographic projection of the second laser region on the first surface.

[0127] In other embodiments, the orthographic projection of the first laser region on the first surface and the orthographic projection of the second laser region on the first surface may also at least partially overlap.

[0128] It should be noted that in practical applications, the orthographic projection area of the first laser region on the first surface and the orthographic projection area of the second laser region on the first surface are different, and the orthographic projection of the first laser region on the first surface and the orthographic projection of the second laser region on the first surface do not overlap, which can exist in the same photovoltaic cell simultaneously; or, the orthographic projection area of the first laser region on the first surface and the orthographic projection area of the second laser region on the first surface are different, and the orthographic projection of the first laser region on the first surface and the orthographic projection of the second laser region on the first surface at least partially overlap, which can exist in the same photovoltaic cell simultaneously.

[0129] In some embodiments, with reference to Figure 9 and Figure 10 , the step of performing the second etching process 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 diffusion barrier layer 116, and the second diffusion barrier layer 126 located on the first surface 110, so as to expose the first textured surface 114 and the doping portion 121, and removing the loose portion 113 and the doped polysilicon layer 102 located in the second laser region 160, and forming a second textured surface 115.

[0130] It should be noted that in step S6, only a part 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 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 is not modified by the second laser treatment, and is lower than the porosity of the loose portion 113.

[0131] On this basis, the second etching process includes two successive etching steps. First, the second chain-like hydrofluoric acid process is used to etch the first surface 110 to remove the silicon glass layer 103 located on the first surface 110, which helps to avoid 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, with the remaining silicon glass layer 103 on the second surface 120 as a protective layer, the second texturing process is used to etch the first surface 110 and the second surface 120 to remove the doped polysilicon layer 102, the first diffusion barrier layer 116, and the second diffusion barrier layer 126 located on the first surface 110, as well as to remove the loose part 113 and the doped polysilicon layer 102 located in the second laser region 160. This helps to ensure that the number of layers of the film layers to be removed by the second texturing process on both the first surface 110 and the second surface 120 is 2 layers, thereby facilitating the improvement of the etching accuracy of the second etching process. In some examples, step S7 finally needs to form a second groove 105 with a second textured surface 115 at the bottom. Designing the second etching process to include two successive etching steps helps to form a good step morphology on the second surface 120, that is, to form a second groove 105 with a controllable surface morphology. For example, it helps to form a second groove 105 with almost the same depth in each region.

[0132] In some embodiments, with reference to Figure 10 and Figure 11 , after the second texturing process, the manufacturing method may further include: cleaning the second surface 120 using an acid pickling process to remove the silicon glass layer 103 located in the second non-laser region 170 to expose the doped polysilicon layer 102 located in the second non-laser region 170.

[0133] In summary, the first laser treatment is used to deepen the doping concentration of the first doping element in the doped layer 101 of this part. On this basis, when the first surface 110 is subsequently subjected to the first etching process, the etching rate of the activation part 111 with a lower doping concentration of the first doping element by the first etching process is much higher than that of the doping part 121. Thus, without the need for an additional mask, the activation part 111 can be removed using the doping part 121 as a barrier layer to form the first textured surface 114, which helps to simplify the manufacturing process of the photovoltaic cell. In addition, compared with using a laser opening process to remove part of the doped layer 101, the combined effect of the first laser treatment and the first etching process helps to reduce the laser damage to the first surface 110 caused by the laser. Moreover, forming a selective emitter structure with the doping part 121 only in some regions of the first surface 110 helps to reduce the contact resistance between the subsequently formed electrode and the doping part 121 while reducing the probability of carrier recombination in other regions of the first surface 110.

[0134] The second laser treatment is used to modify the partial silicon glass layer 103 into a loose part 113. On this basis, when at least the second etching treatment is performed on the second surface 120 subsequently, the etching rate of the loose part 113 with a higher degree of porosity is much higher than that of the remaining silicon glass layer 103. Therefore, without the need for an additional mask, the remaining silicon glass layer 103 can be used as a protective layer to remove the loose part 113 and the doped polysilicon layer 102 opposite to the loose part 113 and form a second textured surface 115, which is beneficial to simplifying the manufacturing process of the photovoltaic cell. Moreover, removing the doped polysilicon layer 102 opposite to the loose part 113 helps to avoid the parasitic absorption of light by the removed doped polysilicon layer 102, and the exposed second textured surface 115 can improve the absorption utilization rate of light, and is also beneficial to ensuring a low contact resistance between the subsequently formed electrode and the remaining doped polysilicon layer 102.

[0135] Another embodiment of the present disclosure also provides a photovoltaic cell prepared by the manufacturing method provided by the foregoing embodiment. The following will describe in detail the photovoltaic cell provided by another embodiment of the present disclosure with reference to the accompanying drawings. It should be noted that the same or corresponding parts as those in the foregoing embodiment will not be described in detail here.

[0136] The photovoltaic cell includes: a photovoltaic cell formed according to the manufacturing method provided by the foregoing embodiment.

[0137] It should be noted that the photovoltaic cell can be a TOPCON cell, a PERC cell, a heterojunction cell or other cells with a passivation structure. By forming the photovoltaic cell according to the manufacturing method provided by the foregoing embodiment, with the help of the first laser treatment and the second laser treatment with different laser types successively, it is beneficial to form a doped part 121 only on a partial area of the first surface 110 and a doped polysilicon layer 102 only on a partial area of the second surface 120 without the need for an additional mask, and expose the first textured surface 114 on the first surface 110 and the second textured surface 115 on the second surface 120 to improve the utilization rate of incident light on the first surface 110 and the second surface 120, thereby improving the photoelectric conversion efficiency of the formed photovoltaic cell.

[0138] In some embodiments, refer to Figure 11, the photovoltaic cell includes: a substrate 100 having opposite first and second surfaces 110 and 120, the first surface 110 including first laser regions 140 and first non-laser regions 150 arranged alternately along a first direction X, the second surface 120 including second laser regions 160 and second non-laser regions 170 arranged alternately along the first direction X; a doping portion 121 located on the first non-laser region 150; a doped polysilicon layer 102 located on the second non-laser region 170; a first groove 104 on the first laser region 140 having a first textured surface 114 as the bottom surface; a second groove 105 on the second laser region 160 having a second textured surface 115 as the bottom surface.

[0139] Thus, on the one hand, the first textured surface 114 can enhance the absorption effect of incident light, and due to the characteristic 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, further improving the absorption utilization rate of the incident light by the first groove 104. Therefore, with the combined cooperation of the first groove 104 and the first textured surface 114, it is beneficial to increase the absorption utilization rate of the incident light by the first surface 110. On the other hand, the second textured surface 115 can enhance the absorption effect of incident light, and due to the characteristic that the second groove 105 is 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 incident light by the second groove 105. Therefore, with the combined cooperation of the second groove 105 and the second textured surface 115, it is beneficial to increase the absorption utilization rate of the incident light by the second surface 120. With such multi-faceted cooperation, it is beneficial to increase the photoelectric conversion efficiency of the photovoltaic cell.

[0140] In some cases, along a second direction Y, the depth of the first groove 104 is greater than the depth of the second groove 105. In some examples, the depth of the first groove 104 can be 2.5 μm to 4 μm, and the depth of the second groove 105 can be 2 μm to 3 μm.

[0141] In some embodiments, the photovoltaic cell may further include: a tunneling layer located between the second surface 120 and the doped polysilicon layer 102, and the tunneling layer and the doped polysilicon layer 102 form a selective passivation contact structure on the second surface 120.

[0142] Those of ordinary skill in the art can understand that the above embodiments are specific embodiments for implementing the present disclosure, and in practical applications, various changes can be made in form and details without departing from the spirit and scope of the embodiments of the present disclosure. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the embodiments of the present disclosure. Therefore, the protection scope of the embodiments of the present disclosure should be determined by the scope defined by the claims.

Claims

1. A manufacturing method of a photovoltaic cell, characterized in that, Comprising: Providing a substrate having opposite first and second surfaces; At least doping the first surface to form a doped layer having a first doping element; Performing a first laser treatment on a part of the doped layer to form an activation part, and the remaining doped layer serving as a doped part, wherein the doping concentration of the first doping element in the activation part is lower than that in the doped part; Using the doped part as a dead layer, performing a first etching treatment on the first surface to remove the activation part and form a first matte surface; At least sequentially forming a doped polysilicon layer having a second doping element and a silicon glass layer on a side of the substrate away from the doped part; At least performing a second laser treatment on a part of the silicon glass layer to form a porous part; Using the remaining silicon glass layer as a protective layer, at least performing a second etching treatment on the second surface to remove the porous part and the doped polysilicon layer opposite to the porous part and form a second matte surface; Wherein, the types of the first doping element and the second doping element are different, and the types of lasers used in the first laser treatment and the second laser treatment are different.

2. The manufacturing method of the photovoltaic cell according to claim 1, wherein, Both the first surface and the second surface are third matte surfaces; after forming the first matte surface and before forming the doped polysilicon layer, further comprising: 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 a side of the doped polysilicon layer away from the polished surface.

3. The manufacturing method of the photovoltaic cell according to claim 2, characterized in that, After forming the first matte surface and before forming the polished surface, further comprising: At least oxidizing the first surface to form a first diffusion barrier layer on the doped part and a second diffusion barrier layer on the first matte surface; The steps of forming the doped polysilicon layer and the silicon glass layer further include: forming the doped polysilicon layer on both the first diffusion barrier layer and the second diffusion barrier layer, and forming the silicon glass layer on a side of the doped polysilicon layer away from the first diffusion barrier layer and the second diffusion barrier layer.

4. The manufacturing method of the photovoltaic cell according to claim 2, characterized in that, After forming the first matte surface and before forming the polished surface, further comprising: At least oxidizing the first surface to form a first diffusion barrier layer on the doped part and a second diffusion barrier layer on the first matte surface; The surface jointly 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. The steps of forming the doped polysilicon layer and the silicon glass layer further include: forming the doped polysilicon layer on the edge region, and forming the silicon glass layer on a side of the doped polysilicon layer away from the edge region.

5. The manufacturing method of a photovoltaic cell according to claim 3 or 4, characterized in that, The first surface includes first laser regions and first non-laser regions alternately arranged in a first direction, and the second surface includes second laser regions and second non-laser regions alternately arranged in the first direction; The step of performing the first laser treatment on a part of the doped layer includes: performing the first laser treatment on the doped layer located in the first laser region to form the activation part located in the first laser region; The step of performing the second laser treatment on at least a 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 porous part located in the second laser area.

6. The manufacturing method of the photovoltaic cell according to claim 5, wherein, The orthographic projection area of the first laser area on the substrate and the orthographic projection area of the second laser area on the substrate are different, and / or, the orthographic projection of the first laser area on the substrate and the orthographic projection of the second laser area on the substrate at least partially overlap or do not overlap.

7. The manufacturing method of a photovoltaic cell according to claim 5, characterized in that, 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 diffusion barrier layer, and the second diffusion barrier layer located on the first surface to expose the first textured surface and the doped part, and removing the porous part and the doped polysilicon layer located in the second laser area, and forming the second textured surface.

8. The manufacturing method of a photovoltaic cell according to claim 7, characterized in that, After performing the second texturing process, it further includes: Cleaning the second surface using an acid pickling 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 manufacturing method of the photovoltaic cell according to claim 1, characterized in that 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 part and form the first textured surface.

10. The manufacturing method of the 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 using the first texturing process, it further includes etching the first surface using a first chain hydrofluoric acid process to remove the oxide layer.

11. The manufacturing method of the photovoltaic cell according to claim 1, characterized in that, The first laser treatment uses red sodium laser, green sodium laser or purple sodium laser, and the second laser treatment uses purple skin laser, green skin laser, green fly laser or purple fly laser.

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

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