Photovoltaic cell and manufacturing method thereof

Abstract

The embodiment of the invention relates to the photovoltaic field, and provides a photovoltaic cell and a manufacturing method thereof, and the photovoltaic cell comprises a silicon substrate of a first surface and a second surface which are opposite to each other along a first direction, and the first surface comprises a plurality of first regions which are arranged at intervals along a second direction; forming an initial doping layer containing a silicon element on the first region based on the silicon substrate, wherein the surface, far away from the silicon substrate, of the initial doping layer comprises at least one second region; forming a germanium-containing layer on the second region; forming an initial grid line at least on one side, away from the second region, of the germanium-containing layer; laser enhanced contact optimization processing is carried out on the initial grid line, germanium elements in the germanium-containing layer and silicon elements in the initial doping layer are promoted to react to form a germanium-silicon alloy layer, the remaining initial doping layer is used as a doping layer, the initial grid line is converted into a grid line, the collection efficiency of the grid line to carriers is at least improved, and the collection efficiency of the carrier is improved. And the light utilization rate of the first surface is improved.

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 utilizes the photovoltaic effect to generate carriers, and then uses electrodes to extract the carriers, thereby facilitating the effective utilization of electrical energy. Photovoltaic cells mainly include BC cells (Back Contact), TOPCON (Tunnel Oxide Passivated Contact) cells, PERC cells (Passivated emitter and real cell), and heterojunction cells, etc.

[0003] Generally, grid lines are used to extract the carriers in the photovoltaic cell, thereby facilitating the effective utilization of electrical energy. However, in order to improve the photoelectric conversion efficiency of the photovoltaic cell, how to improve the collection efficiency of the grid lines for the carriers and how to improve the light utilization rate of the photovoltaic cell still need to be further studied. Summary of the Invention

[0004] Embodiments of the present disclosure provide a photovoltaic cell and a manufacturing method thereof, which are at least beneficial to improving the collection efficiency of the grid lines for the carriers and the light utilization rate of the first surface.

[0005] According to some embodiments of the present disclosure, on the one hand, a manufacturing method of a photovoltaic cell is provided, including: providing a silicon substrate, the silicon substrate having a first surface and a second surface opposite to each other along a first direction, the first surface including a plurality of first regions arranged at intervals along a second direction, the first direction being the thickness direction of the silicon substrate, and the second direction intersecting the first direction; forming an initial doped layer containing silicon elements on the first regions based on the silicon substrate, the surface of the initial doped layer away from the silicon substrate including at least one second region; forming a germanium-containing layer on the second region; forming an initial grid line at least on one side of the germanium-containing layer away from the second region; performing a laser enhanced contact optimization process on the initial grid line to cause a reaction between the germanium element in the germanium-containing layer and the silicon element in the initial doped layer to form a germanium-silicon alloy layer, and the remaining initial doped layer serves as a doped layer, and the initial grid line is transformed into a grid line.

[0006] In some embodiments, the material of the germanium-containing layer includes at least one of germanium oxide, germanium sulfide, or germanium selenide; the step of forming the germanium-containing layer on the second region includes: forming the germanium-containing layer on the second region by means of a coating process; during the process of performing the laser-enhanced contact optimization treatment, at least some of the other elements in the germanium-containing layer other than germanium element volatilize.

[0007] In some embodiments, after performing the laser-enhanced contact optimization treatment, the remaining germanium-containing layer is located between the gate line and the germanium-silicon alloy layer; alternatively, during the process of performing the laser-enhanced contact optimization treatment, all the germanium elements in the germanium-containing layer react with the silicon elements in the initial doping layer to form the germanium-silicon alloy layer, and the other elements in the germanium-containing layer other than germanium element volatilize, and finally the formed gate line and the germanium-silicon alloy layer are in direct contact.

[0008] In some embodiments, the germanium-containing layer is a germanium layer; the step of forming the germanium-containing layer on the second region includes: providing a germanium source, the material of the germanium source includes at least one of germanium hydride, germanium chloride, or tetramethylgermanium; performing a high-temperature decomposition treatment on the germanium source so that germanium atoms are deposited on the second region to form the germanium layer.

[0009] In some embodiments, the step of forming the germanium-containing layer on the second region further includes: forming a mask layer on the surface of the initial doping layer away from the silicon substrate, the mask layer having at least one opening, and one opening exposing one second region; forming the germanium-containing layer on the mask layer and the second region, retaining the germanium-containing layer located on the second region, and removing the germanium-containing layer and the mask layer located on the mask layer.

[0010] In some embodiments, the step of forming the initial gate line includes: printing a conductive paste on the second region; performing a drying treatment on the conductive paste to convert the conductive paste into the initial gate line.

[0011] In some embodiments, the treatment temperature of the drying treatment is 150°C to 500°C.

[0012] In some embodiments, the step of performing the laser-enhanced contact optimization treatment includes: setting the power of the laser generator that generates the laser to be 5W to 20W, and the bias voltage to be 10V to 15V; aligning the laser to scan the initial gate line and the germanium-containing layer, the scanning width of the laser being 0.1mm to 1mm, and the scanning rate of the laser being 10000mm / s to 80000mm / s.

[0013] In some embodiments, both the first region and the second region extend along a third direction, a single first region and a single second region face each other along the first direction, and the third direction, the second direction, and the first direction intersect pairwise; and / or, a single first region and at least two second regions face each other along the first direction.

[0014] In some embodiments, the ratio of the sum of the areas of at least one second region facing the same first region to the area of the first region is 0.4 to 0.9.

[0015] In some embodiments, the step of forming the initial doped layer includes: performing a first doping diffusion process on the first surface to form a first doped layer covering the first surface and doped with a doping element; performing a first patterning process on the first doped layer, and only retaining the first doped layer located in the first region as the initial doped layer.

[0016] In some embodiments, the first region includes a first doped region and a second doped region alternately arranged along the second direction; the step of forming the initial doped layer includes: forming an initial second doped layer on the first doped region, and forming an initial third doped layer on the second doped region; the step of forming the germanium-containing layer includes: forming the germanium-containing layer on both the second regions of the initial second doped layer and the initial third doped layer.

[0017] According to some embodiments of the present disclosure, on the other hand, the present disclosure also provides a photovoltaic cell, including: a silicon substrate having a first surface and a second surface opposite to each other along a first direction, the first surface including a plurality of first regions spaced apart along a second direction, the first direction being the thickness direction of the silicon substrate, and the second direction intersecting the first direction; a doped layer located on the first region and containing silicon element, the surface of the doped layer away from the silicon substrate includes at least one second region, and the doped layer includes a germanium-silicon alloy layer located in the second region; grid lines, at least located on the side of the germanium-silicon alloy layer away from the silicon substrate.

[0018] In some embodiments, the photovoltaic cell further includes: a germanium-containing layer, located between the grid lines and the germanium-silicon alloy layer.

[0019] In some embodiments, the ratio of the content of germanium atoms to the content of silicon atoms in the germanium-silicon alloy layer is 0.1 to 10.

[0020] The technical solutions provided by the embodiments of the present disclosure have at least the following advantages: On the one hand, compared with the conductivity of pure silicon material, the conductivity of the germanium-silicon alloy layer is higher, which is conducive to reducing the transfer resistance of carriers passing through the germanium-silicon alloy layer and finally transmitted to the gate line by means of the higher conductivity in the germanium-silicon alloy layer, so as to improve the collection efficiency of the gate line for carriers and the fill factor of the finally formed photovoltaic cell. On the other hand, compared with the bandgap of pure silicon material, the bandgap of the germanium-silicon alloy layer is smaller, which is conducive to realizing the photoelectric conversion of longer-wavelength infrared light by means of the germanium-silicon alloy layer, thereby improving the short-circuit current of the photovoltaic cell. On the other hand, the doped layer includes a part not directly opposite to the gate line, and the doping concentration of the doping element in the doped layer can be controlled to be relatively low, so as to reduce the parasitic absorption of light by the part of the doped layer not blocked by the gate line, thereby reducing the optical loss caused by the doped layer and improving the utilization rate of light on the first surface as a whole. On the other hand, the doped layer is designed only in a partial area of the first surface, that is, the first area, and the other areas of the first surface except the first area are not blocked by the doped layer, so that the light can be utilized more efficiently. In this way, the multi-faceted effects are conducive to improving the photoelectric conversion efficiency of the photovoltaic cell.

[0021] Moreover, the improvement of the electrical connection performance between the gate line and the doped layer mainly depends on the germanium-silicon alloy layer, and the doping concentration of the doping element in the doped layer does not need to be too high, which is conducive to keeping the doped layer at a better passivation level to improve the open-circuit voltage of the photovoltaic cell.

[0022] In addition, it is beneficial to precisely control the area formed by the germanium-silicon alloy layer by virtue of the high precision and low damage characteristics of laser-enhanced contact optimization processing, so that the germanium-silicon alloy layer will not be formed in the area not blocked by the gate line. Brief Description of the Drawings

[0023] 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 proportional limitation. In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the traditional technologies, the drawings required to be used in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 It is a partial cross-sectional view after forming the first doped layer on the silicon substrate in the manufacturing method of the photovoltaic cell provided by an embodiment of the present disclosure; Figure 2 It is a partial cross-sectional view after forming the initial doped layer on the first area in the manufacturing method of the photovoltaic cell provided by an embodiment of the present disclosure; Figure 3A partial cross-sectional view after forming a mask layer on the surface of the initial doping layer away from the substrate in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 4 A partial cross-sectional view after forming a germanium-containing layer in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 5 A partial cross-sectional view after forming an initial grid line in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 6 The first partial cross-sectional view after forming a grid line in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 7 The second partial cross-sectional view after forming a grid line in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 8 The third partial cross-sectional view after forming a grid line in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 9 A partial cross-sectional view of a silicon substrate provided in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 10 Another partial cross-sectional view after forming an initial doping layer in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 11 Another partial cross-sectional view after forming a germanium-containing layer in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 12 Another partial cross-sectional view after forming an initial grid line in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 13 The fourth partial cross-sectional view after forming a grid line in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 14 The fifth partial cross-sectional view after forming a grid line in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 15 The sixth partial cross-sectional view after forming a grid line in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 16 A partial top view after forming an initial doping layer in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 17 Another partial top view after forming an initial doping layer in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure.

[0025] Explanation of reference numerals: 100, silicon substrate; 110, first surface; 120, second surface; 130, first region; 101, initial doping layer; 111, second region; 121, doping layer; 102, germanium-containing layer; 103, initial gate line; 113, gate line; 104, germanium-silicon alloy layer; 105, mask layer; 115, opening; 106, first doping layer; 119, first passivation layer; 129, second passivation layer.

[0026] 200, silicon substrate; 210, first surface; 220, second surface; 230, first region; 2301, first doping region; 2302, second doping region; 240, spacer region; 201, initial doping layer; 211, second region; 221, doping layer; 2211, second doping layer; 2212, third doping layer; 202, germanium-containing layer; 203, initial gate line; 213, gate line; 204, germanium-silicon alloy layer; 207, initial second doping layer; 217, first tunneling layer; 227, first doped polysilicon layer; 208, initial third doping layer; 218, second tunneling layer; 228, second doped polysilicon layer; 219, first passivation layer; 229, second passivation layer. Detailed implementation manners

[0027] As can be seen from the background art, the collection efficiency of the gate line for carriers needs to be improved, and the utilization rate of light on the first surface needs to be improved.

[0028] Embodiments of the present disclosure provide a photovoltaic cell and a manufacturing method thereof. In the manufacturing method of the photovoltaic cell, on the one hand, compared with the conductivity of pure silicon material, the conductivity of the germanium-silicon alloy layer is higher, which is conducive to reducing the transfer resistance of carriers from the germanium-silicon alloy layer to the grid line by virtue of the higher conductivity in the germanium-silicon alloy layer, so as to improve the collection efficiency of the grid line for carriers and the fill factor of the finally formed photovoltaic cell. On the other hand, compared with the bandgap of pure silicon material, the bandgap of the germanium-silicon alloy layer is smaller, which is conducive to realizing the photoelectric conversion of longer-wavelength infrared light by means of the germanium-silicon alloy layer, thereby improving the short-circuit current of the photovoltaic cell. On the other hand, the doped layer includes a part not facing the grid line, and the doping concentration of the doping element in the doped layer can be controlled to be relatively low, so as to reduce the parasitic absorption of light by the part of the doped layer not blocked by the grid line, thereby reducing the optical loss caused by the doped layer and improving the utilization rate of light on the first surface as a whole. On the other hand, the doped layer is designed only in a partial area, that is, the first area, on the first surface, and the other areas on the first surface except the first area are not blocked by the doped layer, so that the light can be utilized more efficiently. In this way, the multi-faceted effects are conducive to improving the photoelectric conversion efficiency of the photovoltaic cell. Moreover, the improvement of the electrical connection performance between the grid line and the doped layer mainly depends on the germanium-silicon alloy layer, and the doping concentration of the doping element in the doped layer does not need to be too high, which is conducive to keeping the doped layer at a better passivation level to improve the open-circuit voltage of the photovoltaic cell. In addition, it is conducive to precisely controlling the area formed by the germanium-silicon alloy layer by virtue of the high precision and low damage characteristics of the laser-enhanced contact optimization process, so that the germanium-silicon alloy layer will not be formed in the area not blocked by the grid line.

[0029] 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 indicating 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" is more than two, unless otherwise specifically and clearly defined.

[0030] Referring to "embodiments" herein 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. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein may be combined with other embodiments.

[0031] In the description of the embodiments of the present disclosure, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there can be three relationships, for example, A and / or B, which can mean: there is A, there is both A and B, and there is B. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0032] In the description of the embodiments of the present disclosure, the term "a plurality of" means two or more (including two). Similarly, "a plurality of groups" means two or more groups (including two groups), and "a plurality of sheets" means two or more sheets (including two sheets).

[0033] In the description of the embodiments of the present disclosure, the orientation or positional relationship indicated by technical terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the embodiments of the present disclosure.

[0034] In the description of the embodiments of the present disclosure, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to specific circumstances.

[0035] In the corresponding drawings of the embodiments of the present disclosure, for better understanding and convenience of description, the thickness and area of the layer are enlarged. When describing a component (such as a layer, film, region or substrate) on or on the surface of another component, the component can be "directly" on the surface of the other component, or there can be a third component between the two components. On the contrary, when describing a component on the surface of another component or when a surface of a component forms or is provided with another component, it means that there is no third component between the two components. In addition, when describing a component "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.

[0036] In the description of the embodiments of the present disclosure, when a certain component "includes" another component, unless otherwise stated, other components are not excluded, and other components may further be included. In addition, when a component such as a layer, film, region, or plate is referred to as being "on / located on" another component, it may be "directly on" another component (i.e., located on the surface of another component with no other components therebetween), or there may be other components therebetween. In addition, when a component such as a layer, film, region, or plate is "directly located on" another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it means that no other components are located therebetween.

[0037] 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.

[0038] The following will elaborate on the embodiments of the present disclosure in conjunction with the accompanying drawings. However, those of ordinary skill in the art can understand that in the embodiments of the present disclosure, many technical details are 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 claimed in the embodiments of the present disclosure can still be implemented.

[0039] An embodiment of the present disclosure provides a method for manufacturing a photovoltaic cell. The following will elaborate in detail on the method for manufacturing a photovoltaic cell provided by an embodiment of the present disclosure in conjunction with the accompanying drawings.

[0040] Refer to Figures 1 to 17 , the method for manufacturing a photovoltaic cell may include the following steps: S1: Refer to Figure 1 or Figure 9 , provide a silicon substrate (100 or 200), the silicon substrate (100 or 200) has a first surface (110 or 210) and a second surface (120 or 220) opposite to each other along a first direction X, the first surface (110 or 210) includes a plurality of first regions (130 or 230) arranged at intervals along a second direction Y, the first direction X is the thickness direction of the silicon substrate (100 or 200), and the second direction Y intersects the first direction X.

[0041] S2: In combination with referring to Figure 1 and Figure 2 , or refer to Figure 10, an initial doped layer (101 or 201) containing silicon elements is formed on the first region (130 or 230) based on a silicon substrate (100 or 200). The surface of the initial doped layer (101 or 201) far from the silicon substrate (100 or 200) includes at least one second region (111 or 211).

[0042] It should be noted that, taking the structures shown in Figure 1 and Figure 2 as examples, the initial doped layer 101 can be transformed from doping a doping element into the silicon substrate 100. Therefore, Figure 2 the initially formed doped layer 101 contains silicon elements.

[0043] Optionally, referring to Figure 1 , a first doping diffusion process is performed on the first surface 110. Along the first direction X, a part of the thickness of the silicon substrate 100 is transformed into a first doped layer 106 doped with a doping element, and the first doped layer 106 is formed based on the silicon substrate 100. Then, the first doped layer 106 also contains silicon elements, and the remaining thickness of the silicon substrate 100 serves as the silicon substrate 100 in subsequent steps; in combination with referring to Figure 1 and Figure 2 , a first patterning process is performed on the first doped layer 106, and only the first doped layer 106 located in the first region 130 is retained as the initial doped layer 101.

[0044] It should be noted that Figure 10 the formation method of the initial doped layer 201 shown in Figure 1 and Figure 2 is similar to the preparation method shown in Figure 4 or referring to Figure 11 , and will not be elaborated here. S3: Referring to

[0045] or referring to Figure 5 or referring to Figure 12 , a germanium-containing layer (102 or 202) is formed on the second region (111 or 211).

[0046] S5: In combination with referring to Figures 5 to 8 , or in combination with referring to Figures 12 to 15 , a laser-enhanced contact optimization process is performed on the initial gate line (103 or 203), prompting the germanium element in the germanium-containing layer (102 or 202) to react with the silicon element in the initial doped layer (101 or 201) to form a germanium-silicon alloy layer (104 or 204). The remaining initial doped layer (101 or 201) serves as a doped layer (121 or 221), and the initial gate line (103 or 203) is transformed into a gate line (113 or 213).

[0047] It should be noted that Figures 1 to 8 FIGs. are a series of partial cross-sectional schematic views corresponding to the steps in the manufacturing method of a photovoltaic cell provided in an embodiment of the present disclosure to form a photovoltaic cell with grid lines on both sides; Figures 9 to 15 FIGs. are another series of partial cross-sectional schematic views corresponding to the steps in the manufacturing method of a photovoltaic cell provided in an embodiment of the present disclosure to form a BC cell. Each figure will be described in detail later.

[0048] It should be noted that the region where the initial doping layer (101 or 201) contacts the silicon substrate (100 or 200) is the first region (130 or 230), and only a part of the surface of the initial doping layer (101 or 201) away from the silicon substrate (100 or 200) is the second region (111 or 211). In other words, in the orthographic projection on the first surface (110 or 210), the orthographic projection of the second region (111 or 211) only coincides with a part of the orthographic projection of the first region (130 or 230). That is, along the first direction X, the orthographic projection of the second region (111 or 211) on the first surface (110 or 210) is the second orthographic projection, and the orthographic projection of the first region (130 or 230) on the first surface (110 or 210) is the first orthographic projection, and the second orthographic projection only coincides with a part of the first orthographic projection.

[0049] Based on this, a germanium-containing layer (102 or 202) is formed only in a part of the surface of the initial doping layer (101 or 201) away from the silicon substrate (100 or 200). Then, after a germanium-silicon alloy layer (104 or 204) is formed based on the germanium-containing layer (102 or 202), only a part of the surface of the initial doping layer (101 or 201) away from the silicon substrate (100 or 200) is replaced by the surface of the germanium-silicon alloy layer (104 or 204), and the remaining surface is still composed of the initial doping layer (101 or 201), and the remaining initial doping layer (101 or 201) serves as the doping layer (121 or 221). In other words, the germanium-silicon alloy layer (104 or 204) is embedded in the doping layer (121 or 221).

[0050] Furthermore, the initial gate line (103 or 203) is designed to be formed at least on the side of the germanium-containing layer (102 or 202) away from the second region (111 or 211). After the laser-enhanced contact optimization process, the surfaces of the germanium-silicon alloy layer (104 or 204) away from the silicon substrate (100 or 200) will face the gate line (113 or 213), and at least part of the doped layer (121 or 221) is not blocked by the gate line (113 or 213), or in other words, the doped layer (121 or 221) includes a portion that is not opposite to the gate line (113 or 213). In this way, on the one hand, compared with the conductivity of pure silicon material, the conductivity of the germanium-silicon alloy layer (104 or 204) is higher, which is conducive to reducing the transfer resistance of carriers from the germanium-silicon alloy layer (104 or 204) to the gate line (113 or 213) through the higher conductivity in the germanium-silicon alloy layer (104 or 204), reducing the line resistance, improving the collection efficiency of the gate line (113 or 213) for carriers, and improving the fill factor of the finally formed photovoltaic cell. On the other hand, compared with the bandgap of pure silicon material, the bandgap of the germanium-silicon alloy layer (104 or 204) is smaller, which is conducive to realizing the photoelectric conversion of longer-wavelength infrared light through the germanium-silicon alloy layer (104 or 204), thus improving the short-circuit current of the photovoltaic cell. On the other hand, since the doped layer (121 or 221) includes a portion that is not opposite to the gate line (113 or 213), the doping concentration of the doping element in the doped layer (121 or 221) can be controlled to be relatively low, so as to reduce the parasitic absorption of light by the portion of the doped layer (121 or 221) that is not blocked by the gate line (113 or 213), thereby reducing the optical loss caused by the doped layer (121 or 221) and improving the overall light utilization rate of the first surface (110 or 210). On the other hand, the doped layer (121 or 221) is designed only in a partial area of the first surface (110 or 210), that is, the first region (130 or 230), and the other areas of the first surface (110 or 210) except the first region (130 or 230) are not blocked by the doped layer (121 or 221), which can have a higher light utilization rate. In this way, the combined effects of multiple aspects are beneficial to improving the photoelectric conversion efficiency of the photovoltaic cell.

[0051] It should be emphasized that, compared with the current technical solution of improving the electrical connection performance between the gate line and the doping layer to improve the carrier collection efficiency of the gate line and increasing the doping concentration of the doping elements in the entire doping layer to a certain level, in the manufacturing method of the photovoltaic cell provided by an embodiment of the present disclosure, the electrical connection performance between the gate line (113 or 213) and the doping layer (121 or 221) is not simply improved by relying on the doping concentration of the doping elements in the doping layer (121 or 221). Instead, while controlling the doping concentration of the doping elements in the doping layer (121 or 221) to be relatively low, the electrical connection performance between the gate line (113 or 213) and the doping layer (121 or 221) is improved by means of the germanium-silicon alloy layer (104 or 204) with higher conductivity. Moreover, not only is the doping layer (121 or 221) designed in only a partial area, i.e., the first area (130 or 230), on the first surface (110 or 210), but also only a partial area on the surface of the initial doping layer (101 or 201) far from the silicon substrate (100 or 200) is designed as the second area (111 or 211), so that the finally formed germanium-silicon alloy layer (104 or 204) is only opposite to the gate line (113 or 213). Therefore, while reducing the transfer resistance of the carriers finally transferred to the gate line (113 or 213) via the germanium-silicon alloy layer (104 or 204), the doping concentration of the doping elements in the doping layer (121 or 221) can be further reduced to reduce the parasitic absorption of light by the doping layer (121 or 221). In other words, the improvement of the electrical connection performance between the gate line (113 or 213) and the doping layer (121 or 221) mainly relies on the germanium-silicon alloy layer (104 or 204), and the doping concentration of the doping elements in the doping layer (121 or 221) does not need to be too high, which is beneficial to keeping the doping layer (121 or 221) at a better passivation level to improve the open-circuit voltage of the photovoltaic cell.

[0052] In an example, in the current technical solution of improving the electrical connection performance between the gate line and the doping layer and increasing the doping concentration of the doping elements in the entire doping layer to a certain level, the doping concentration of the doping elements is called the first doping concentration; in the manufacturing method of the photovoltaic cell provided by an embodiment of the present disclosure, the doping concentration of the doping elements in the doping layer (121 or 221) is called the second doping concentration. Among them, the first doping concentration is higher than the second doping concentration.

[0053] In addition, in step S5: forming the germanium-silicon alloy layer (104 or 204), it is beneficial to utilize the high precision and low damage characteristics of the laser enhanced contact optimization process to precisely control the property regulation of the materials in the operation area, that is, precisely control the area where the germanium-silicon alloy layer (104 or 204) is formed, so that the germanium-silicon alloy layer (104 or 204) is all opposite to the gate line (113 or 213) and will not be formed in the area not blocked by the gate line (113 or 213).

[0054] The following will describe each step in the manufacturing method of the photovoltaic cell provided by an embodiment of the present disclosure in more detail with reference to the accompanying drawings.

[0055] In some embodiments, the bandgap of the germanium-silicon alloy layer (104 or 204) can be 0.67 eV to 1.1 eV. For example, it can be 0.68 eV, 0.69 eV, 0.7 eV, 0.71 eV, 0.72 eV, 0.73 eV, 0.74 eV, 0.75 eV, 0.76 eV, 0.77 eV, 0.78 eV, 0.79 eV, 0.8 eV, 0.81 eV, 0.82 eV, 0.83 eV, 0.84 eV, 0.85 eV, 0.86 eV, 0.87 eV, 0.88 eV, 0.89 eV, 0.9 eV, 0.91 eV, 0.92 eV, 0.93 eV, 0.94 eV, 0.95 eV, 0.96 eV, 0.97 eV, 0.98 eV, 0.99 eV, 1 eV, 1.01 eV, 1.02 eV, 1.03 eV, 1.04 eV, 1.05 eV, 1.06 eV, 1.07 eV, 1.08 eV, or 1.09 eV, etc.

[0056] In this way, it is beneficial to utilize the characteristic of the low bandgap of the germanium-silicon alloy layer (104 or 204) to broaden the response range of the photovoltaic cell to infrared light, enabling infrared light in a longer wavelength band to be utilized by the photovoltaic cell, thereby increasing the short-circuit current of the photovoltaic cell.

[0057] The following will describe in detail the type of the finally formed photovoltaic cell.

[0058] In some embodiments, referring to Figure 6 , Figure 7 or Figure 8 , the finally formed photovoltaic cell can be a cell with grid lines on both sides. For example, it can be a PERC cell (Passivated Emitter Rear Cell), a TOPCon cell (Tunnel Oxide Passivated Contact), a HIT / HJT cell (Heterojunction Technology), a solar thin-film cell, or any combination of a tandem cell. Among them, the solar thin-film cell includes but is not limited to a perovskite solar thin-film cell, a copper indium selenide solar thin-film cell, a gallium arsenide solar thin-film cell, and a cadmium sulfide solar thin-film cell. The tandem cell includes but is not limited to a perovskite cell stacked with a crystalline silicon cell, a perovskite cell stacked with a perovskite cell, and a perovskite cell stacked with a thin-film cell.

[0059] Among them, Figure 6The first partial cross-sectional schematic diagram after forming grid lines in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 7 The second partial cross-sectional schematic diagram after forming grid lines in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 8 The third partial cross-sectional schematic diagram after forming grid lines in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure.

[0060] In this way, the first surface 110 can be regarded as the front surface of the finally formed photovoltaic cell, that is, the first surface 110 can be used as the light-receiving surface, and the doped layer 121 formed on the first region 130 of the first surface 110 can be regarded as a selective emitter. In some examples, the materials of the initial doped layer 101 and the doped layer 121 can both be silicon material layers including doping elements, that is, both the initial doped layer 101 and the doped layer 121 can be film layers including doping elements and silicon elements.

[0061] It should be noted that in practical applications, the finally formed photovoltaic cell can be a single-sided cell, and the first surface can be regarded as the front surface of the photovoltaic cell, that is, the first surface can be used as the light-receiving surface to receive incident light, and the second surface can be used as the backlight surface; or, the finally formed photovoltaic cell can be a double-sided cell, then both the first surface and the second surface can be used as the light-receiving surface 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.

[0062] In some embodiments, with reference to Figure 1 and Figure 2 , step S2 of forming the initial doped layer 101 may include: with reference to Figure 1 , performing a first doping diffusion process on the first surface 110 to form a first doped layer 106 covering the first surface 110 and doped with doping elements; with reference to Figure 1 and Figure 2 , performing a first patterning process on the first doped layer 106, and only retaining the first doped layer 106 located in the first region 130 as the initial doped layer 101.

[0063] It should be noted that Figure 1 is a partial cross-sectional schematic diagram after forming a first doped layer on a silicon substrate in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 2 is a partial cross-sectional schematic diagram after forming an initial doped layer on the first region in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure.

[0064] In addition, during the process of performing the first doping diffusion process on the first surface 110, along the first direction X, a portion of the thickness of the silicon substrate 100 is converted into a first doped layer 106 doped with a doping element, and the remaining thickness of the silicon substrate 100 serves as the silicon substrate 100 in subsequent steps.

[0065] In some examples, the silicon substrate 100 may be an N-type semiconductor substrate doped with an N-type doping element, and the first doped layer 106, the initial doped layer 101, and the subsequently formed doped layers all contain a P-type doping element. In other examples, the silicon substrate 100 may also be a P-type semiconductor substrate doped with a P-type doping element, and the first doped layer 106, the initial doped layer 101, and the subsequently formed doped layers all contain an N-type doping element.

[0066] In some examples, the N-type doping element may be at least one of group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As); the P-type semiconductor substrate is doped with a P-type element, and the P-type doping element may be at least one of group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0067] It should be noted that when the finally formed photovoltaic cell can be a cell with grid lines on both sides, the second surface can also perform steps S1 to S5 similar to the first surface, that is, a local doped layer is made on the second surface, then a germanium-containing layer is made in a local area of the doped layer, and at least an initial grid line is formed on the side of the germanium-containing layer away from the second surface, and the initial grid line is subjected to laser enhanced contact optimization treatment. Finally, the germanium element in the germanium-containing layer reacts with the silicon element in the doped layer to form a germanium-silicon alloy layer, and the initial grid line is converted into a grid line. In some examples, the local doped layer formed on the second surface may be a passivated contact stack including a tunneling layer and a polysilicon layer doped with a doping element.

[0068] In other embodiments, referring to Figure 13 、 Figure 14 or Figure 15 , the finally formed photovoltaic cell can be a back contact cell, that is, a BC cell. The BC cell includes but is not limited to an IBC cell (Interdigitated Back Contact), an HBC cell (Heterojunction Back Contact), a TBC cell (TOPCon Back Contact), or an HPBC cell (Hybrid Passivated BackContact), etc. Thus, the first surface 210 can be regarded as the back surface of the finally formed photovoltaic cell.

[0069] Among them,Figure 13 The fourth partial cross-sectional schematic diagram after forming grid lines in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 14 The fifth partial cross-sectional schematic diagram after forming grid lines in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 15 The sixth partial cross-sectional schematic diagram after forming grid lines in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure.

[0070] In some cases, referring to Figure 9 , a plurality of first regions 230 may include a first doped region 2301 and a second doped region 2302 arranged alternately along the second direction Y; referring to Figure 10 , step S2 of forming the initial doped layer 201 may include: forming an initial second doped layer 207 on the first doped region 2301, and forming an initial third doped layer 208 on the second doped region 2302; referring to Figure 11 , step S3 of forming the germanium-containing layer 202 may include: forming the germanium-containing layer 202 on the second regions 211 of both the initial second doped layer 207 and the initial third doped layer 208.

[0071] In other words, step S2 is divided into two major steps of preparing the initial second doped layer 207 and preparing the initial third doped layer 208. Different from step S2, in step S3, the germanium-containing layer 202 formed on the second regions 111 of both the initial second doped layer 207 and the initial third doped layer 208 can be prepared in the same step. The following provides a detailed description of step S2.

[0072] It should be noted that Figure 9 A partial cross-sectional schematic diagram of a silicon substrate provided in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 10 Another partial cross-sectional schematic diagram after forming the initial doped layer in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 11 Another partial cross-sectional schematic diagram after forming the germanium-containing layer in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure.

[0073] In some examples, referring to Figure 10 , the initial second doped layer 207 may be a first passivation contact stack including a first tunneling layer 217 and a first doped polysilicon layer 227 doped with a first type of doping element; the initial third doped layer 208 may be a second passivation contact stack including a second tunneling layer 218 and a second doped polysilicon layer 228 doped with a second type of doping element.

[0074] It should be noted that the first type of doping element is one of a P-type doping element and an N-type doping element, and the second type of doping element is the other of a P-type doping element and an N-type doping element. For the convenience of description, in the following, it is taken as an example that the first type of doping element is a P-type doping element and the second type of doping element is an N-type doping element. In addition, Figure 10 Taking the finally formed BC cell as a TBC cell (TOPCon Back Contact, referring to an interdigitated passivated back contact cell) as an example, in practical applications, the BC cell can also be an HBC cell (Heterojunction Back Contact), or a back contact cell), or an HPBC cell (Hybrid Passivated Back Contact), etc.

[0075] Reference Figure 10 , the steps of forming the initial second doping layer 207 may include: forming an initial first tunneling layer (not shown in the figure) on the first surface 210; forming an initial first film layer (not shown in the figure) on the side of the initial first tunneling layer away from the silicon substrate 200; performing a second doping diffusion process on the initial first film layer to form an initial first doped film (not shown in the figure) covering the side of the initial first tunneling layer away from the silicon substrate 200 and doped with a P-type doping element; performing a first patterning process on the initial first tunneling layer and the initial first doped film to remove the initial first tunneling layer and the initial first doped film on the region of the first surface 210 except the first doping region 2301, and only retaining the initial first tunneling layer located on the first doping region 2301 as the first tunneling layer 217, and only retaining the initial first doped film located on the first doping region 2301 as the first doped polysilicon layer 227.

[0076] In some examples, the steps of forming the initial first tunneling layer may include: performing a first thermal oxidation process on the first surface 210 to form an initial first tunneling layer including silicon oxide. It should be noted that during the process of performing the first thermal oxidation process on the first surface 210, along the first direction X, a part of the thickness of the silicon substrate 200 is converted into an initial first tunneling layer including silicon oxide, and the remaining thickness of the silicon substrate 200 serves as the silicon substrate 200 in subsequent steps.

[0077] In some examples, the initial first film layer may be a polysilicon film layer; in other examples, the initial first film layer may be an amorphous silicon film layer. In the step of performing a second doping diffusion process on the initial first film layer, the initial first film layer is also crystallized, such as annealing, so that the formed initial first doped film is a polysilicon film doped with a P-type doping element.

[0078] In some examples, in the step of performing a second doping diffusion process on the initial first film layer, not only an initial first doped film doped with a P-type doping element is formed, but also a silicon glass layer doped with a P-type doping element (not shown in the figure) is formed. For example, the initial first doped film is a boron-doped polysilicon film, and the silicon glass layer doped with a P-type doping element is a borosilicate glass layer. It should be noted that in the subsequent first patterning process, the borosilicate glass layer is first removed, and then the initial first tunneling layer and the initial first doped film on the region of the first surface 210 except for the first doping region 2301 are removed.

[0079] In one example, along the first direction X, the thickness of the stack formed by the initial first tunneling layer and the initial first doped film is 100 nm to 300 nm. For example, it can be 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 270 nm, 280 nm or 290 nm, etc.; the thickness of the borosilicate glass layer is 20 nm to 80 nm. For example, it can be 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm or 75 nm, etc.

[0080] In some examples, the step of performing a first patterning process on the initial first tunneling layer and the initial first doped film may include: using a laser to perform a patterned film opening process on the region of the first surface 210 except for the first doping region 2301, then removing the borosilicate glass layer, and then using an alkali polishing process to remove the laser residue and the initial first tunneling layer and the initial first doped film on the region of the first surface 210 except for the first doping region 2301.

[0081] Continue to refer to Figure 10 , the step of forming the initial third doped layer 208 may include: forming an initial second tunneling layer (not shown in the figure) on the surface formed by the initial second doped layer 207 and the remaining first surface 210; forming an initial second film layer (not shown in the figure) on the side of the initial second tunneling layer away from the silicon substrate 200; performing a third doping diffusion process on the initial second film layer to form an initial second doped film (not shown in the figure) that covers the side of the initial second tunneling layer away from the silicon substrate 200 and is doped with an N-type doping element; performing a second patterning process on the initial second tunneling layer and the initial second doped film to remove the initial second tunneling layer and the initial second doped film on the region of the first surface 210 except for the second doping region 2302, and only retaining the initial second tunneling layer located on the second doping region 2302 as the second tunneling layer 218, and only retaining the initial first doped film located on the second doping region 2302 as the second doped polysilicon layer 228.

[0082] In some examples, the step of forming the initial second tunneling layer may include: performing a second thermal oxidation process on the first surface 210 not shielded by the initial second doping layer 207 to form an initial second tunneling layer including silicon oxide. It should be noted that during the second thermal oxidation process of the first surface 210, along the first direction X, a part of the thickness of the silicon substrate 200 is converted into the initial second tunneling layer including silicon oxide, and the remaining thickness of the silicon substrate 200 serves as the silicon substrate 200 in subsequent steps.

[0083] In some examples, the initial second film layer may be a polysilicon film layer; in other examples, the initial second film layer may be an amorphous silicon film layer. In the step of performing a third doping diffusion process on the initial second film layer, the initial second film layer is also crystallized, such as by annealing, so that the formed initial second doped film is a polysilicon film doped with an N-type doping element.

[0084] In some examples, in the step of performing a third doping diffusion process on the initial second film layer, not only is the initial second doped film doped with an N-type doping element formed, but also a silicon glass layer doped with an N-type doping element is formed. For example, the initial second doped film is a phosphorus-doped polysilicon film, and the silicon glass layer doped with an N-type doping element is a phosphosilicate glass layer. It should be noted that in the subsequent second patterning process, the phosphosilicate glass layer is first removed, and then the initial second tunneling layer and the initial second doped film on the region of the first surface 210 except the second doping region 2302 are removed.

[0085] In one example, along the first direction X, the thickness of the stack formed by the initial second tunneling layer and the initial second doped film is 100 nm to 300 nm. For example, it can be 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 270 nm, 280 nm, or 290 nm, etc.; the thickness of the phosphosilicate glass layer is 30 nm to 60 nm. For example, it can be 35 nm, 40 nm, 45 nm, 50 nm, or 55 nm, etc.

[0086] In some examples, the step of performing second patterning on the initial second tunneling layer and the initial second doped film may include: performing a patterned film opening process on the region of the first surface 210 except the second doping region 2302 using a laser, then removing the phosphosilicate glass layer, and then using an alkali polishing process to remove the laser residue and the initial second tunneling layer and the initial second doped film on the region of the first surface 210 except the second doping region 2302.

[0087] In some examples, refer to Figures 9 to 15, there is also a spacer region 240 between adjacent first doping regions 2301 and second doping regions 2302. The total orthographic projection area of multiple spacer regions 240 on the first surface 210 accounts for 20% - 60% of the first surface 210. For example, it can be 25%, 30%, 35%, 40%, 45%, 50% or 55%, etc.; the total orthographic projection area of multiple first doping regions 2301 on the first surface 210 accounts for 20% - 40% of the first surface 210. For example, it can be 25%, 30% or 35%, etc.; the total orthographic projection area of multiple second doping regions 2302 on the first surface 210 accounts for 20% - 40% of the first surface 210. For example, it can be 25%, 30% or 35%, etc.

[0088] In some examples, during the steps of forming the initial first doping film and the initial second doping film, there is a phenomenon of overplating, such that on a partial region of the second surface 220 and on the side surface connecting the first surface 210 and the second surface 220, there are both the initial first doping film and the initial second doping film. Further, there is also a silicon glass layer doped with P-type doping elements generated along with the initial first doping film, and a silicon glass layer doped with N-type doping elements generated along with the initial second doping film; after forming the initial second doping layer 207 and the initial third doping layer 208, the method for preparing a photovoltaic cell further includes: pickling the second surface 220 and the side surface connecting the first surface 210 and the second surface 220 to remove the initial first doping film and the initial second doping film on the second surface 220 and on the side surface connecting the first surface 210 and the second surface 220, and removing the silicon glass layer doped with P-type doping elements and the silicon glass layer doped with N-type doping elements.

[0089] It should be noted that in combination with reference Figures 11 to 15 , the doping layer 221 formed in step S5 includes a second doping layer 2211 located on the first doping region 2301 and a third doping layer 2212 located on the second doping region 2302. Based on the reaction between the germanium element in the germanium-containing layer 202 and the silicon element in the initial doping layer 201, along the first direction X, at least a partial thickness of the initial second doping layer 207 in the second region 211 is transformed into a germanium-silicon alloy layer 204, and the remaining initial second doping layer 207 serves as the second doping layer 2211. At least a partial thickness of the initial third doping layer 208 in the second region 211 is transformed into a germanium-silicon alloy layer 204, and the remaining initial second doping layer 207 serves as the third doping layer 2212.

[0090] In some embodiments, in combination with reference Figure 4 and Figure 5 , or, in combination with reference Figure 11 and Figure 12After forming the germanium-containing layer (102 or 202) and before forming the initial gate line (103 or 203), the manufacturing method of the photovoltaic cell may further include: forming a first passivation layer (119 or 219) on the surface jointly constituted by the initial doping layer (101 or 201), the germanium-containing layer (102 or 202), and the remaining first surface (110 or 210).

[0091] It should be noted that in practical applications, regardless of whether the finally formed photovoltaic cell is a cell with gate lines on both sides or a BC cell, after forming the germanium-containing layer and before forming the initial gate line, the first passivation layer may not be made, and the initial gate line may be directly formed on the germanium-containing layer to finally form a photovoltaic cell as shown in Figure 7 , Figure 8 , Figure 14 or Figure 15 . Figure 4 , Figure 5 , Figure 11 and Figure 12 take the finally formed photovoltaic cell including the first passivation layer (119 or 219), and after performing step S5, there is a remaining germanium-containing layer (102 or 202) between the gate line (113 or 213) and the germanium-silicon alloy layer (104 or 204) as an example.

[0092] It should be noted that referring to Figure 6 or Figure 13 , the finally formed gate line (113 or 213) will be electrically connected to the first passivation layer (119 or 219) and contact and connect with the germanium-containing layer (102 or 202). In other embodiments, the finally formed gate line will also be electrically connected to the first passivation layer and contact and connect with the germanium-silicon alloy layer.

[0093] In some cases, the first passivation layer (119 or 219) can be formed by a deposition process. In some examples, the material of the first passivation layer (119 or 219) may include at least one of alumina, silicon nitride, silicon oxide, and silicon oxynitride.

[0094] In some embodiments, in combination with referring to Figure 4 and Figure 5 , or in combination with referring to Figure 11 and Figure 12 , the manufacturing method of the photovoltaic cell may further include: forming a second passivation layer (129 or 229) on the second surface (120 or 220). It should be noted that Figure 5 and Figure 12 take forming the second passivation layer (129 or 229) after forming the germanium-containing layer (102 or 202) and before forming the initial gate line (103 or 203) as an example. In practical applications, the second passivation layer can also be formed in other steps.

[0095] In some cases, a deposition process can be used to form the second passivation layer (129 or 229). In some examples, the material of the second passivation layer (129 or 229) may include at least one of aluminum oxide, silicon nitride, silicon oxide, and silicon oxynitride.

[0096] In some cases, referring to Figure 6 , the finally formed photovoltaic cell is a cell with grid lines on both sides. The grid lines finally formed on the second side (not shown in the figure) will be electrically connected to the second passivation layer 129 and contact and connect to other film layers located under the second passivation layer 129.

[0097] The following details the degree to which the germanium-silicon alloy layer (104 or 204) is embedded in the doped layer (121 or 221).

[0098] In some embodiments, in combination with reference to Figure 2 and Figure 6 , or in combination with reference to Figure 10 and Figure 13 , along the first direction X, the thickness of the initial doped layer (101 or 201) formed in step S2 is higher than the thickness of the germanium-silicon alloy layer (104 or 204) formed in step S5. In other words, in step S5, along the direction away from the silicon substrate (100 or 200), only silicon elements in only a partial thickness of the initial doped layer (101 or 201) located in the second region (111 or 211) react with the diffused germanium elements, so that only a partial thickness of the initial doped layer (101 or 201) located in the second region (111 or 211) is converted into the germanium-silicon alloy layer (104 or 204).

[0099] In some other embodiments, in combination with reference to Figure 2 and Figure 8 , or in combination with reference to Figure 10 and Figure 15 , along the first direction X, the thickness of the initial doped layer (101 or 201) formed in step S2 is equal to the thickness of the germanium-silicon alloy layer (104 or 204) formed in step S5. In other words, in step S5, along the first direction X, silicon elements in the entire thickness of the initial doped layer (101 or 201) located in the second region (111 or 211) all react with the diffused germanium elements, so that the entire thickness of the initial doped layer (101 or 201) located in the second region (111 or 211) is converted into the germanium-silicon alloy layer (104 or 204).

[0100] The following details the preparation process of the germanium-containing layer (102 or 202) and the laser enhanced contact optimization process in step S5.

[0101] In some embodiments, referring to Figure 4 or Figure 11, the material of the germanium-containing layer (102 or 202) may include at least one of germanium oxide, germanium sulfide, or germanium selenide; S3: The step of forming the germanium-containing layer (102 or 202) on the second region (111 or 211) may include: forming the germanium-containing layer (102 or 202) on the second region (111 or 211) by using a coating process; with reference to Figures 6 to 8 , or with reference to Figures 13 to 15 , during the process of performing the step S5 laser-enhanced contact optimization treatment, at least some of the other elements in the germanium-containing layer (102 or 202) other than germanium element volatilize.

[0102] It should be emphasized that the germanium-containing layer (102 or 202) is not a film layer containing only germanium element. In step S5, other elements in the germanium-containing layer (102 or 202) other than germanium element volatilize. By adjusting the process parameters of the step S5 laser-enhanced contact optimization treatment, the volatilization degree of other elements in the germanium-containing layer (102 or 202) other than germanium element can be adjusted. The following details the reaction degree between the germanium element in the germanium-containing layer (102 or 202) and the silicon element in the initial doping layer (101 or 201), and the volatilization degree of other elements in the germanium-containing layer (102 or 202) other than germanium element.

[0103] In some cases, with reference to Figure 6 , Figure 7 , Figure 13 or Figure 14 , after performing the step S5 laser-enhanced contact optimization treatment, the remaining germanium-containing layer (102 or 202) is located between the gate line (113 or 213) and the germanium-silicon alloy layer (104 or 204). In other words, only a partial amount of germanium element in the germanium-containing layer (102 or 202) reacts with the silicon element in the initial doping layer (101 or 201) (with reference to Figure 4 or Figure 11 ) to form the germanium-silicon alloy layer (104 or 204), and the remaining germanium element that has not penetrated into the initial doping layer (101 or 201) still exists in the remaining germanium-containing layer (102 or 202).

[0104] It should be noted that after the laser-enhanced contact optimization process in step S5, the remaining germanium-containing layer (102 or 202) can be regarded as an intermediate layer located between the gate line (113 or 213) and the germanium-silicon alloy layer (104 or 204). The specific materials of the intermediate layer include at least the following two examples: In some examples, during the laser-enhanced contact optimization process in step S5, only some of the elements other than germanium in the germanium-containing layer (102 or 202) volatilize, and the remaining germanium elements that have not penetrated into the initial doped layer (101 or 201) and the other elements that have not volatilized are present in the remaining germanium-containing layer (102 or 202). Then, the material of the finally formed intermediate layer includes at least one of germanium oxide, germanium sulfide, or germanium selenide; In other examples, during the laser-enhanced contact optimization process in step S5, all the elements other than germanium in the germanium-containing layer (102 or 202) volatilize, and only the germanium elements that have not penetrated into the initial doped layer (101 or 201) and the germanium elements present in the remaining germanium-containing layer (102 or 202) remain. Then, the finally formed intermediate layer is a germanium layer.

[0105] In other cases, with reference to Figure 4 and Figure 8 , or with reference to Figure 11 and Figure 15 , during the laser-enhanced contact optimization process in step S5, all the germanium elements in the germanium-containing layer (102 or 202) react with the silicon elements in the initial doped layer (101 or 201) to form a germanium-silicon alloy layer (104 or 204), and the elements other than germanium in the germanium-containing layer (102 or 202) volatilize. Finally, the formed gate line (113 or 213) and the germanium-silicon alloy layer (104 or 204) are in direct contact. In other words, there is no intermediate layer between the gate line (113 or 213) and the germanium-silicon alloy layer (104 or 204).

[0106] In other embodiments, with reference to Figure 4 or Figure 11 , the germanium-containing layer (102 or 202) can be a germanium layer; The step of forming the germanium-containing layer (102 or 202) on the second region (111 or 211) may include: providing a germanium source, and the material of the germanium source may include at least one of germanium hydride, germanium chloride, or tetramethylgermanium; performing a high-temperature decomposition treatment on the germanium source so that germanium atoms are deposited on the second region (111 or 211) to form a germanium layer.

[0107] It should be noted that during the high-temperature decomposition process, the elements other than germanium in the germanium source are discharged in the form of gas, and only germanium atoms will be deposited on the second region (111 or 211) to form a germanium layer.

[0108] With reference to Figures 4 to 8 , or with reference to Figures 11 to 15, when performing the step S5 of laser enhanced contact optimization treatment subsequently, the germanium element in the germanium layer will react with the silicon element in the initial doping layer (101 or 201) to form a germanium-silicon alloy layer (104 or 204). The following will elaborate on the reaction degree between the germanium element in the germanium-containing layer (102 or 202) serving as the germanium layer and the silicon element in the initial doping layer (101 or 201).

[0109] In some cases, referring to Figure 6 , Figure 7 , Figure 13 or Figure 14 , after performing the step S5 of laser enhanced contact optimization treatment, the remaining germanium layer is located between the gate line (113 or 213) and the germanium-silicon alloy layer (104 or 204). In other words, only a partial amount of the germanium element in the germanium-containing layer (102 or 202) serving as the germanium layer reacts with the silicon element in the initial doping layer (101 or 201) (referring to Figure 4 or Figure 11 ) to form a germanium-silicon alloy layer (104 or 204), and the remaining germanium element that has not penetrated into the initial doping layer (101 or 201) still exists in the remaining germanium-containing layer (102 or 202). It should be noted that after performing the step S5 of laser enhanced contact optimization treatment, the remaining germanium-containing layer (102 or 202) can be regarded as an intermediate layer located between the gate line (113 or 213) and the germanium-silicon alloy layer (104 or 204). In this case, the finally formed intermediate layer is a germanium layer.

[0110] In other cases, in combination with referring to Figure 4 and Figure 8 , or in combination with referring to Figure 11 and Figure 15 , during the process of performing the step S5 of laser enhanced contact optimization treatment, all the germanium elements in the germanium-containing layer (102 or 202) serving as the germanium layer react with the silicon elements in the initial doping layer (101 or 201) to form a germanium-silicon alloy layer (104 or 204), then the finally formed gate line (113 or 213) and the germanium-silicon alloy layer (104 or 204) are in direct contact. In other words, there is no intermediate layer between the gate line (113 or 213) and the germanium-silicon alloy layer (104 or 204).

[0111] In some embodiments, in combination with referring to Figure 3 and Figure 4 , S3: The step of forming the germanium-containing layer 102 on the second region 111 may further include: referring to Figure 3 , forming a mask layer 105 on the surface of the initial doping layer 101 away from the silicon substrate 100, the mask layer 105 having at least one opening 115, and one opening 115 exposing one second region 111; in combination with referring to Figure 3 and Figure 4, a germanium-containing layer 102 is formed on the mask layer 105 and the second region 111. The germanium-containing layer 102 located on the second region 111 is retained, and the germanium-containing layer 102 located on the mask layer 105 and the mask layer 105 are removed. In this way, by using the cooperation of the mask layer 105 with the opening 115 and the coating process or the deposition process, it is beneficial to accurately form the germanium-containing layer 102 on the second region 111, effectively avoiding the germanium-containing layer 102 from being formed on the region not covered by the subsequently formed gate lines.

[0112] Among them, Figure 3 is a partial cross-sectional schematic diagram after forming a mask layer on the surface of the initial doping layer away from the substrate in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 4 is a partial cross-sectional schematic diagram after forming a germanium-containing layer in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure.

[0113] In some cases, the coating process may include a spraying process, a spin coating process, or a drop coating process.

[0114] In some cases, the deposition process may include a sputtering process or an atomic layer deposition (ALD) process.

[0115] It should be noted that Figure 3 and Figure 4 take the finally formed photovoltaic cell as an example of a cell with gate lines on both sides. In practical applications, the finally formed photovoltaic cell is also applicable to BC cells. In addition, when the finally formed photovoltaic cell is a BC cell, the mask layer not only exposes the second region of the initial second doping layer, that is, the second region opposite to the first doping region, but also exposes the second region of the initial third doping layer, that is, the second region opposite to the second doping region. In other words, in the mask layer, a part of the openings expose the second region of the initial second doping layer, and the remaining openings expose the second region of the initial third doping layer, which is beneficial to simultaneously form a germanium-containing layer on the second regions of both the initial second doping layer and the initial third doping layer by means of the same mask layer, so as to simplify the process of manufacturing a photovoltaic cell.

[0116] In some embodiments, referring to Figure 5 or Figure 12 , S4: The step of forming the initial gate lines (103 or 203) may include: printing a conductive paste on the second region (111 or 211); drying the conductive paste to convert the conductive paste into the initial gate lines (103 or 203).

[0117] Among them, Figure 5 is a partial cross-sectional schematic diagram after forming the initial gate lines in the manufacturing method of a photovoltaic cell provided by an embodiment of the present disclosure; Figure 12Another partial cross-sectional schematic diagram after forming the initial grid line in the manufacturing method of the photovoltaic cell provided by an embodiment of the present disclosure.

[0118] It should be noted that during the process of forming the initial grid line (103 or 203), only the conductive paste is dried, and the conductive paste is not subjected to the conventional high-temperature sintering treatment, so as to preliminarily solidify the conductive paste into the initial grid line (103 or 203). With reference to Figure 5 and Figure 6 , or with reference to Figure 12 and Figure 13 , subsequently, with the help of the laser enhanced contact optimization treatment in step S5, the initial grid line (103 or 203) is further promoted to form, so as to form the final grid line (113 or 213) in contact with the germanium-containing layer (102 or 202) or the germanium-silicon alloy layer (104 or 204), and the contact performance between the grid line (113 or 213) and the germanium-containing layer (102 or 202) or the germanium-silicon alloy layer (104 or 204) is improved by the laser enhanced contact optimization treatment. For example, the probability of carriers recombining at the contact between the grid line (113 or 213) and the germanium-containing layer (102 or 202) or the germanium-silicon alloy layer (104 or 204) is reduced. In addition, it is beneficial to avoid the damage to the photovoltaic cell caused by high temperature during the high-temperature sintering treatment step, so as to realize the preparation of the grid line (113 or 213) in a lower temperature environment, thereby being beneficial to improving the overall electrical performance of the photovoltaic cell.

[0119] In some embodiments, in S4: during the process of forming the initial grid line (103 or 203), the treatment temperature of the drying treatment can be 150°C to 500°C. For example, it can be 170°C, 200°C, 220°C, 250°C, 280°C, 300°C, 330°C, 350°C, 360°C, 400°C, 420°C, 450°C or 480°C, etc. It should be noted that the treatment temperature of the high-temperature sintering treatment is generally higher than 700°C, and the treatment temperature of the drying treatment is lower than the treatment temperature of the high-temperature sintering treatment, so as to be beneficial to realizing the preparation of the grid line (113 or 213) in a lower temperature environment, so as to improve the overall electrical performance of the photovoltaic cell.

[0120] In some embodiments, with reference to Figure 5 and Figure 6 , or with reference to Figure 12 and Figure 13 , the steps of the laser enhanced contact optimization treatment include: setting the power of the laser generator generating the laser can be 5W to 20W, and the bias voltage can be 10V to 15V; aligning the laser to scan the initial grid line (103 or 203) and the germanium-containing layer (102 or 202), the scanning width of the laser can be 0.1mm to 1mm, and the scanning rate of the laser can be 10000mm / s to 80000mm / s.

[0121] In some examples, the power of the laser generator can be 6W, 7W, 8W, 9W, 10W, 11W, 12W, 13W, 14W, 15W, 16W, 17W, 18W, 19W, etc.

[0122] In some examples, the bias voltage of the laser generator can be 10.5V, 11V, 11.5V, 12V, 12.5V, 13V, 13.5V, 14V, 14.5V, etc.

[0123] In some examples, the scanning width of the laser can be 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, etc.

[0124] In some examples, the scanning rate of the laser can be 15000mm / s, 20000mm / s, 25000mm / s, 30000mm / s, 35000mm / s, 40000mm / s, 45000mm / s, 60000mm / s, 65000mm / s, 70000mm / s, 75000mm / s, etc.

[0125] The corresponding relationship between the first region 130 and the second region 111 will be described in detail below. The corresponding relationship between the first region 130 and the second region 111 described below is applicable to both the battery with grid lines on both sides and the BC battery.

[0126] In some embodiments, with reference to Figure 16 , both the first region 130 and the second region 111 extend along the third direction Z. A single first region 130 and a single second region 111 face each other along the first direction X. The third direction Z, the second direction Y, and the first direction X intersect pairwise.

[0127] It should be noted that Figure 16 is a partial top view schematic diagram after forming the initial doping layer in the manufacturing method of the photovoltaic cell provided in an embodiment of the present disclosure. Figure 16 The second region 111 is schematically shown on the surface of the initial doping layer 101 far from the silicon substrate 100 with a dashed line. In addition, Figure 16 the corresponding relationship between the first region 130 and the second region 111 shown is also applicable to Figure 13 or Figure 14 the BC battery shown.

[0128] In some cases, with reference to Figure 16 and Figure 6 or Figure 7, in the positive projection of the gate line 113 and the germanium-containing layer 102 formed in step S5 on the first surface 110, they coincide, which is beneficial to making one side of the gate line 113 facing the first surface 110 in contact connection with the germanium-containing layer 102, so as to increase the contact area between the gate line 113 and the germanium-containing layer 102, thereby improving the contact performance between the gate line 113 and the germanium-containing layer 102, improving the collection efficiency of the gate line 113 for carriers, and avoiding too high doping concentration of doping elements in the doping layer 121, so as to improve the overall light utilization rate of the first surface 110.

[0129] In some other cases, with reference to Figure 16 and Figure 8 , in the positive projection of the gate line 113 and the germanium-silicon alloy layer 104 formed in step S5 on the first surface 110, they coincide, which is beneficial to making one side of the gate line 113 facing the first surface 110 in contact connection with the germanium-silicon alloy layer 104, so as to increase the contact area between the gate line 113 and the germanium-silicon alloy layer 104, thereby improving the contact performance between the gate line 113 and the germanium-silicon alloy layer 104, improving the collection efficiency of the gate line 113 for carriers, and avoiding too high doping concentration of doping elements in the doping layer 121, so as to improve the overall light utilization rate of the first surface 110.

[0130] In some other embodiments, with reference to Figure 17 , a single first region 130 and at least two second regions 111 face each other along the first direction X.

[0131] It should be noted that Figure 17 is another partial top view schematic diagram after forming the initial doping layer in the manufacturing method of the photovoltaic cell provided by an embodiment of the present disclosure. Figure 17 The second region 111 is schematically shown on the surface of the initial doping layer 101 far from the silicon substrate 100 with a dashed box. In addition, Figure 17 the corresponding relationship between the first region 130 and the second region 111 shown can also be applied to Figure 13 or Figure 14 the BC cell shown. It should be noted that in some cases, with reference to Figure 17 and Figure 4 , in step S3, the number of germanium-containing layers 102 formed on the surface of the same initial doping layer 101 far from the silicon substrate 100 is at least 2; with reference to Figure 17 and Figure 5 , in step S4, not only the initial gate line 103 is formed on the side of the germanium-containing layer 102 far from the second region 111, but also the initial gate line 103 is located in the interval between two adjacent second regions 111 facing the same first region 130. In other words, in the first direction X, the initial gate line 103 not only faces the germanium-containing layer 102, but also faces the interval between two adjacent germanium-containing layers 102 facing the same first region 130; with reference to Figure 17 andFigure 6 or Figure 7 In step S5, the orthographic projection of the germanium-containing layer 102 on the first surface 110 is located within the orthographic projection of the gate line 113 on the first surface 110.

[0132] In this way, on the side of a single doping layer 121 away from the silicon substrate 100, a plurality of germanium-containing layers 102 are provided. A single gate line 113 is not only in contact connection with the plurality of germanium-containing layers 102, but also in contact connection with the portion of the single doping layer 121 located between two second regions 111, which is beneficial to ensuring an appropriate contact area between the gate line 113 and the germanium-containing layer 102 while not only avoiding too high a doping concentration of doping elements in the region of the doping layer 121 not blocked by the gate line 113, but also avoiding too high a doping concentration of doping elements in the region of the doping layer 121 partially blocked by the gate line 113, so as to further improve the overall light utilization rate of the first surface 110 and further reduce the overall doping concentration of doping elements in the doping layer 121, thereby reducing the probability of carriers recombining at the contact between the doping layer 121 and the silicon substrate 100.

[0133] In some other cases, with reference to Figure 17 and Figure 8 , or with reference to Figure 17 and Figure 15 , a plurality of germanium-silicon alloy layers 104 are embedded on the side of a single doping layer 121 away from the silicon substrate 100. A single gate line 113 is not only in contact connection with the plurality of germanium-silicon alloy layers 104, but also in contact connection with the portion of the single doping layer 121 located between two germanium-silicon alloy layers 104, which is beneficial to ensuring an appropriate contact area between the gate line 113 and the germanium-silicon alloy layer 104 while not only avoiding too high a doping concentration of doping elements in the region of the doping layer 121 not blocked by the gate line 113, but also avoiding too high a doping concentration of doping elements in the region of the doping layer 121 partially blocked by the gate line 113, so as to further improve the overall light utilization rate of the first surface 110 and further reduce the overall doping concentration of doping elements in the doping layer 121, thereby reducing the probability of carriers recombining at the contact between the doping layer 121 and the silicon substrate 100.

[0134] In other embodiments, on the same first surface, a partial number of the first regions and second regions facing each other along the first direction both extend along the third direction, and a single first region and a single second region face each other along the first direction; the remaining number of single first regions and at least two second regions face each other along the first direction.

[0135] In the above various embodiments, with reference to Figures 1 to 17, the ratio of the sum of the areas of at least one second region (111 or 211) facing the same first region (130 or 230) to the area of the first region (130 or 230) can be 0.4 to 0.9. For example, it can be 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, or 0.85, etc. Thus, in the finally formed doped layer (121 or 221) and germanium-containing layer (102 or 202), in at least one germanium-containing layer (102 or 202) corresponding to the same doped layer (121 or 221), the layout area occupied by the germanium-containing layer (102 or 202) corresponding to the same doped layer (121 or 221) on the first surface (110 or 210) and the layout area occupied by this doped layer (121 or 221) on the first surface (110 or 210) have a ratio of 0.4 to 0.9.

[0136] It should be noted that in one first region (130 or 230) and at least one second region (111 or 211) corresponding to the same initial doped layer (101 or 201), if the sum of the areas of the second regions (111 or 211) is less than 0.4 of the area of the first region (130 or 230), the contact area between the finally formed gate line (113 or 213) and the germanium-containing layer (102 or 202) or germanium-silicon alloy layer (104 or 204) is too small, which is not conducive to improving the contact performance between the gate line (113 or 213) and the germanium-containing layer (102 or 202) or germanium-silicon alloy layer (104 or 204); if the sum of the areas of the second regions (111 or 211) is greater than 0.9 of the area of the first region (130 or 230), most regions of the finally formed doped layer (121 or 221) are embedded with germanium-silicon alloy layers (104 or 204), and the regions in the doped layer (121 or 221) not blocked by the gate line (113 or 213) are few, which is not conducive to improving the light utilization rate of the doped layer (121 or 221). Based on this, designing the ratio of the sum of the areas of at least one second region (111 or 211) facing the same first region (130 or 230) to the area of the first region (130 or 230) to be 0.4 to 0.9 is beneficial to ensuring an appropriate contact area between the gate line (113 or 213) and the germanium-containing layer (102 or 202) or germanium-silicon alloy layer (104 or 204), and improving the light utilization rate of the doped layer (121 or 221).

[0137] In some embodiments, referring to Figure 2 or Figure 10 , along the first direction X, the thickness of the initial doped layer (101 or 201) formed in step S2 can be 100 nm to 300 nm; referring to Figure 6 , Figure 7 , Figure 8 , Figure 13 , Figure 14 orFigure 15 In step S5, the thickness of the germanium-silicon alloy layer (104 or 204) formed can be 10 nm to 300 nm. For example, it can be 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 270 nm, 280 nm or 290 nm, etc. In other words, referring to Figure 6 , Figure 7 , Figure 13 or Figure 14 , the germanium-silicon alloy layer (104 or 204) formed in step S5 can be partially embedded in the doped layer (121 or 221); referring to Figure 8 or Figure 15 , the germanium-silicon alloy layer (104 or 204) formed in step S5 can also penetrate through the doped layer (121 or 221) along the first direction X.

[0138] In some embodiments, referring to Figure 4 or Figure 11 , along the first direction X, the thickness of the germanium-containing layer (102 or 202) formed in step S3 is the first thickness; referring to Figure 6 , Figure 7 , Figure 13 or Figure 14 , the thickness of the germanium-containing layer (102 or 202) finally remaining between the gate line (113 or 213) and the germanium-silicon alloy layer (104 or 204) is the second thickness, and the ratio of the second thickness to the first thickness is less than or equal to 50%. For example, it can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40% or 45%, etc.

[0139] In some other embodiments, referring to Figure 8 or Figure 15 , the gate line (113 or 213) is in direct contact with the germanium-silicon alloy layer (104 or 204). In other words, no germanium-containing layer will remain in step S5.

[0140] In some examples, referring to Figure 4 or Figure 11 , along the first direction X, the thickness of the germanium-containing layer (102 or 202) formed in step S3 can be 10 nm to 100 nm. For example, it can be 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm or 90 nm, etc.

[0141] In some embodiments, referring toFigure 6 , Figure 7 , Figure 8 , Figure 13 , Figure 14 or Figure 15 , the doping concentration of the doping element in the doping layer (121 or 221) can be 1×10 19 atom / cm 3 ~ 8×10 19 atom / cm 3 .

[0142] In summary, in the finally formed photovoltaic cell, the germanium-silicon alloy layer (104 or 204) will be blocked by the grid lines (113 or 213), and the doping layer (121 or 221) includes the part that is not blocked by the grid lines (113 or 213). On the one hand, compared with the conductivity of pure silicon material, the conductivity of the germanium-silicon alloy layer (104 or 204) is higher, which is conducive to reducing the transfer resistance of carriers from the germanium-silicon alloy layer (104 or 204) to the grid lines (113 or 213) through the higher conductivity in the germanium-silicon alloy layer (104 or 204), reducing the line resistance, so as to improve the collection efficiency of the grid lines (113 or 213) for carriers and the fill factor of the finally formed photovoltaic cell; on the other hand, compared with the band gap of pure silicon material, the band gap of the germanium-silicon alloy layer (104 or 204) is smaller, which is conducive to realizing the photoelectric conversion of longer-wavelength infrared light through the germanium-silicon alloy layer (104 or 204), thereby improving the short-circuit current of the photovoltaic cell; on the other hand, the doping layer (121 or 221) includes the part that is not directly opposite to the grid lines (113 or 213), and the doping concentration of the doping element in the doping layer (121 or 221) can be controlled to be relatively low to reduce the parasitic absorption of light by the part of the doping layer (121 or 221) that is not blocked by the grid lines (113 or 213), thereby reducing the optical loss caused by the doping layer (121 or 221) and improving the overall light utilization rate of the first surface (110 or 210); on the other hand, the doping layer (121 or 221) is designed only in a partial area of the first surface (110 or 210), that is, the first area (130 or 230), and the other areas of the first surface (110 or 210) except the first area (130 or 230) are not blocked by the doping layer (121 or 221), which can have a higher light utilization rate. In this way, the multi-faceted effects are conducive to improving the photoelectric conversion efficiency of the photovoltaic cell. Moreover, the improvement of the electrical connection performance between the grid lines (113 or 213) and the doping layer (121 or 221) mainly depends on the germanium-silicon alloy layer (104 or 204), and the doping concentration of the doping element in the doping layer (121 or 221) does not need to be too high, which is conducive to keeping the doping layer (121 or 221) at a better passivation level to improve the open-circuit voltage of the photovoltaic cell.

[0143] In addition, it is beneficial to utilize the high precision and low damage characteristics of laser-enhanced contact optimization to precisely control the region where the germanium-silicon alloy layer (104 or 204) is formed, such that the germanium-silicon alloy layer (104 or 204) is not formed in the region not shielded by the gate lines (113 or 213).

[0144] Another embodiment of the present disclosure further provides a photovoltaic cell, which is formed by the manufacturing method of the photovoltaic cell provided in the foregoing embodiment. The following will describe in detail the photovoltaic cell provided in 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 elaborated herein.

[0145] Reference Figure 7 、 Figure 8 、 Figure 14 or Figure 15 ,the photovoltaic cell includes: a silicon substrate (100 or 200) having a first surface (110 or 210) and a second surface (120 or 220) opposite to each other along a first direction X, the first surface (110 or 210) includes a plurality of first regions (130 or 230) arranged at intervals along a second direction Y, the first direction X is the thickness direction of the silicon substrate (100 or 200), and the second direction Y intersects the first direction X; a doped layer (121 or 221) located on the first region (130 or 230) and containing silicon element, the surface of the doped layer (121 or 221) away from the silicon substrate (100 or 200) includes at least one second region (111 or 211), and a germanium-silicon alloy layer (104 or 204) is provided on the second region (111 or 211) of the doped layer (121 or 221); gate lines (113 or 213), at least located on the side of the germanium-silicon alloy layer (104 or 204) away from the silicon substrate (100 or 200).

[0146] It should be noted that the surfaces of the germanium-silicon alloy layers (104 or 204) away from the silicon substrates (100 or 200) are all facing the gate lines (113 or 213), and at least part of the doped layer (121 or 221) is not blocked by the gate lines (113 or 213), or in other words, the doped layer (121 or 221) includes a part that is not facing the gate lines (113 or 213). Based on this, on the one hand, compared with the conductivity of pure silicon materials, the conductivity of the germanium-silicon alloy layers (104 or 204) is higher, which is conducive to reducing the transfer resistance of carriers passing through the germanium-silicon alloy layers (104 or 204) and finally reaching the gate lines (113 or 213) by means of the higher conductivity in the germanium-silicon alloy layers (104 or 204), reducing the line resistance, so as to improve the collection efficiency of the gate lines (113 or 213) for carriers and the fill factor of the finally formed photovoltaic cell; on the other hand, compared with the bandgap of pure silicon materials, the bandgap of the germanium-silicon alloy layers (104 or 204) is smaller, which is conducive to realizing the photoelectric conversion of longer-wavelength infrared light by means of the germanium-silicon alloy layers (104 or 204), thereby improving the short-circuit current of the photovoltaic cell; on the other hand, since the doped layer (121 or 221) includes a part that is not facing the gate lines (113 or 213), the doping concentration of the doping elements in the doped layer (121 or 221) can be controlled to be relatively low, so as to reduce the parasitic absorption of light by the part of the doped layer (121 or 221) that is not blocked by the gate lines (113 or 213), thereby reducing the optical loss caused by the doped layer (121 or 221) and improving the overall light utilization rate of the first surface (110 or 210); on the other hand, the doped layer (121 or 221) is designed only in a partial area of the first surface (110 or 210), that is, the first region (130 or 230), and the other regions of the first surface (110 or 210) except the first region (130 or 230) are not blocked by the doped layer (121 or 221), which can have a higher light utilization rate. In this way, the multi-faceted effects are conducive to improving the photoelectric conversion efficiency of the photovoltaic cell.

[0147] In some embodiments, referring to Figure 6 、 Figure 7 、 Figure 13 or Figure 14 ,the photovoltaic cell may further include: a germanium-containing layer (102 or 202) located between the gate line (113 or 213) and the germanium-silicon alloy layer (104 or 204).

[0148] In some cases, referring to Figure 6 、 Figure 7 、 Figure 13 or Figure 14 ,along the first direction X, the thickness of the germanium-containing layer (102 or 202) is less than or equal to 50 nm. For example, it can be 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm or 45 nm, etc.

[0149] If the thickness of the germanium-containing layer (102 or 202) is greater than 50 nm, the germanium-containing layer (102 or 202) between the gate line (113 or 213) and the germanium-silicon alloy layer (104 or 204) is too thick. On the one hand, it overly increases the carrier transmission distance, which is not conducive to the collection of carriers by the gate line (113 or 213). On the other hand, it will make the height of the gate line (113 or 213) too high, which is not conducive to the subsequent contact connection between the solder strip and the gate line (113 or 213), affecting the structural stability of the photovoltaic cell. Therefore, along the first direction X, designing the thickness of the germanium-containing layer (102 or 202) to be less than or equal to 50 nm is beneficial to shortening the carrier transmission distance as much as possible, so as to improve the collection efficiency of carriers by the gate line (113 or 213) and reduce the height of the gate line (113 or 213).

[0150] In some cases, referring to Figure 6 or Figure 13 , the photovoltaic cell may further include: a first passivation layer (119 or 219), located on the surface jointly formed by the doped layer (121 or 221), the germanium-containing layer (102 or 202) and the remaining first surface (110 or 210), and the gate line (113 or 213) is electrically connected to the first passivation layer (119 or 219) and is in contact connection with the germanium-containing layer (102 or 202); a second passivation layer (129 or 229), located on the second surface (120 or 220).

[0151] In some other embodiments, referring to Figure 8 or Figure 15 , the gate line (113 or 213) is in direct contact with the germanium-silicon alloy layer (104 or 204).

[0152] It should be noted that in practical applications, based on the photovoltaic cell shown in Figure 8 or Figure 15 , the photovoltaic cell may further include: a first passivation layer (not shown in the figure), located on the surface jointly formed by the doped layer (121 or 221) and the remaining first surface (110 or 210), and the gate line (113 or 213) is electrically connected to the first passivation layer (119 or 219) and is in contact connection with the germanium-silicon alloy layer (104 or 204); a second passivation layer (not shown in the figure), located on the second surface (120 or 220).

[0153] In some embodiments, referring to Figure 6 , Figure 7 , Figure 8 , Figure 13 , Figure 14 or Figure 15 , along the first direction X, the ratio of the content of germanium atoms to the content of silicon atoms in the germanium-silicon alloy layer (104 or 204) can be 0.1 - 10.

[0154] In some examples, the ratio of the content of germanium atoms to the content of silicon atoms in the germanium-silicon alloy layer (104 or 204) can be 1:10; in other examples, the ratio of the content of germanium atoms to the content of silicon atoms in the germanium-silicon alloy layer (104 or 204) can be 10:1.

[0155] In some embodiments, referring to Figure 6 、 Figure 7 、 Figure 8 、 Figure 13 、 Figure 14 or Figure 15 , the thickness of the germanium-silicon alloy layer (104 or 204) can be 10 nm to 300 nm.

[0156] In some embodiments, referring to Figure 6 、 Figure 7 、 Figure 8 、 Figure 13 、 Figure 14 or Figure 15 , the doping element can be a P-type doping element or an N-type doping element, and the doping concentration of the doping element in the doping layer (121 or 221) can be 1×10 19 atom / cm 3 ~5×10 19 atom / cm 3 , for example, it can be 1.2×10 19 atom / cm 3 、1.5×10 19 atom / cm 3 、1.8×10 19 atom / cm 3 、2×10 19 atom / cm 3 、2.3×10 19 atom / cm 3 、2.5×10 19 atom / cm 3 、2.8×10 19 atom / cm 3 、3×10 19 atom / cm 3 、3.2×10 19 atom / cm 3 、3.5×10 19 atom / cm 3 、3.7×10 19 atom / cm 3 、4×10 19 atom / cm 3 、4.2×10 19atom / cm 3 , 4.5×10 19 atom / cm 3 or 4.8×10 19 atom / cm 3 wait.

[0157] In other embodiments, reference Figure 6 , Figure 7 , Figure 8 , Figure 13 , Figure 14 or Figure 15 , the doping concentration of the doping element in the doping layer (121 or 221) can be 5×10 19 atom / cm 3 ~8×10 19 atom / cm 3 , for example, it can be 5.2×10 19 atom / cm 3 , 5.5×10 19 atom / cm 3 , 5.8×10 19 atom / cm 3 , 6×10 19 atom / cm 3 , 6.3×10 19 atom / cm 3 , 6.5×10 19 atom / cm 3 , 6.8×10 19 atom / cm 3 ,7×10 19 atom / cm 3 , 7.2×10 19 atom / cm 3 , 7.5×10 19 atom / cm 3 or 7.8×10 19 atom / cm 3 wait.

[0158] In some embodiments, reference Figure 16 , the first area 130 and the second area 111 both extend along the third direction Z, and a single first area 130 and a single second area 111 are directly opposite to each other along the first direction X. In this way, referring to Figure 6 , Figure 7 , Figure 8 , Figure 13 , Figure 14 or Figure 15, the positive projections of the grid lines (113 or 213) and the germanium-silicon alloy layer (104 or 204) on the first surface (110 or 210) coincide.

[0159] In some other embodiments, referring to Figure 17 , a single first region 130 and at least two second regions 111 face each other along the first direction X. Thus, referring to Figure 6 , Figure 7 , Figure 8 , Figure 13 , Figure 14 or Figure 15 , the positive projection of the germanium-silicon alloy layer (104 or 204) on the first surface (110 or 210) is located within the positive projection of the grid line (113 or 213) on the first surface (110 or 210). On the side of a single doping layer (121 or 221) away from the silicon substrate (100 or 200), a plurality of germanium-silicon alloy layers (104 or 204) are embedded. A single grid line (113 or 213) not only faces a plurality of germanium-silicon alloy layers (104 or 204), but also is in contact connection with the portion of the single doping layer (121 or 221) located between two germanium-silicon alloy layers (104 or 204).

[0160] In other embodiments, on the same first surface, in a partial number of first regions, the first region and the second region facing each other along the first direction both extend along the third direction, and a single first region and a single second region face each other along the first direction; in the remaining number of first regions, a single first region and at least two second regions face each other along the first direction.

[0161] Another embodiment of the present disclosure provides a photovoltaic module, which is formed by connecting a plurality of photovoltaic cells provided by the foregoing embodiments, or by connecting photovoltaic cells formed by the manufacturing methods of a plurality of photovoltaic cells provided by the foregoing embodiments. It should be noted that the same or corresponding parts as the foregoing embodiments will not be described in detail here.

[0162] The photovoltaic module includes: a battery string, which is formed by connecting a plurality of photovoltaic cells provided by the foregoing embodiments, or by connecting photovoltaic cells formed by the manufacturing methods of a plurality of photovoltaic cells provided by the foregoing embodiments; an encapsulation adhesive film for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulation adhesive film facing away from the battery string.

[0163] Those of ordinary skill in the art can understand that the above embodiments are specific embodiments for implementing the present disclosure. In actual applications, various changes can be made in form and details without departing from the spirit and scope of the embodiments of the present disclosure. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of the present disclosure. Therefore, the protection scope of the embodiments of the present disclosure should be subject to the scope defined by the claims.

Claims

1. A method for manufacturing a photovoltaic cell, characterized in that: include: Providing a silicon substrate, the silicon substrate having a first surface and a second surface opposite to each other along a first direction, the first surface comprising a plurality of first regions arranged at intervals along a second direction, the first direction being a thickness direction of the silicon substrate, and the second direction intersecting with the first direction; Based on the silicon substrate, an initial doping layer containing silicon elements is formed on the first region, wherein a surface of the initial doping layer away from the silicon substrate includes at least one second region; forming a germanium-containing layer on the second region; forming an initial gate line at least on a side of the germanium-containing layer away from the second region; The initial gate line is subjected to laser enhanced contact optimization treatment to cause the germanium element in the germanium-containing layer to react with the silicon element in the initial doping layer to form a germanium-silicon alloy layer, and the remaining initial doping layer is used as a doping layer, and the initial gate line is converted into a gate line.

2. The method for manufacturing a photovoltaic cell according to claim 1, characterized in that: The material of the germanium-containing layer includes at least one of germanium oxide, germanium sulfide or germanium selenide; The step of forming the germanium-containing layer on the second region includes: forming the germanium-containing layer on the second region using a coating process; During the laser enhanced contact optimization process, at least part of the elements other than germanium in the germanium-containing layer volatilizes.

3. The method for manufacturing a photovoltaic cell according to claim 2, characterized in that: After the laser enhanced contact optimization process is performed, the remaining germanium-containing layer is located between the gate line and the germanium-silicon alloy layer; Alternatively, during the laser enhanced contact optimization treatment, the germanium element in the germanium-containing layer reacts with the silicon element in the initial doping layer to form the germanium-silicon alloy layer, and the elements other than the germanium element in the germanium-containing layer volatilize, and the gate line finally formed is in direct contact with the germanium-silicon alloy layer.

4. The method for manufacturing a photovoltaic cell according to claim 1, characterized in that: The germanium-containing layer is a germanium layer; The step of forming the germanium-containing layer on the second region includes: providing a germanium-containing source, wherein the material of the germanium-containing source includes at least one of germanium hydride, germanium chloride or tetramethylgermanium; performing high-temperature decomposition treatment on the germanium-containing source so that germanium atoms are deposited on the second region to form the germanium layer.

5. The method for manufacturing a photovoltaic cell according to claim 2 or 4, characterized in that: The step of forming the germanium-containing layer on the second region further comprises: forming a mask layer on a surface of the initial doping layer away from the silicon substrate, wherein the mask layer has at least one opening, and one of the openings exposes one of the second regions; The germanium-containing layer is formed on the mask layer and the second region, the germanium-containing layer on the second region is retained, and the germanium-containing layer and the mask layer on the mask layer are removed.

6. The method for manufacturing a photovoltaic cell according to any one of claims 1 to 4, characterized in that: The step of forming the initial gate line includes: printing a conductive paste on the second area; and drying the conductive paste to transform the conductive paste into the initial gate line.

7. The method for manufacturing a photovoltaic cell according to claim 6, characterized in that: The drying process is carried out at a temperature of 150°C to 500°C.

8. The method for manufacturing a photovoltaic cell according to any one of claims 1 to 4, characterized in that: The steps of performing the laser enhanced contact optimization treatment include: setting the power of the laser generating the laser to 5W~20W and the bias voltage to 10V~15V; aiming the laser at the initial gate line and the germanium-containing layer for scanning, the scanning width of the laser is 0.1mm~1mm, and the scanning rate of the laser is 10000mm / s~80000mm / s.

9. The method for manufacturing a photovoltaic cell according to claim 1, characterized in that: The first zone and the second zone both extend along a third direction, a single first zone and a single second zone face each other along the first direction, and the third direction, the second direction and the first direction intersect each other in pairs; and / or a single first zone and at least two second zones face each other along the first direction.

10. The method for manufacturing a photovoltaic cell according to claim 1 or 9, characterized in that: The ratio of the sum of the areas of at least one second area directly opposite to the same first area to the area of ​​the first area is 0.4-0.

9.

11. The method for manufacturing a photovoltaic cell according to claim 1, characterized in that: The step of forming the initial doping layer comprises: Performing a first doping diffusion process on the first surface to form a first doping layer covering the first surface and doped with a doping element; The first doping layer is subjected to a first patterning process, and only the first doping layer located in the first region is retained as the initial doping layer.

12. The method for manufacturing a photovoltaic cell according to claim 1, characterized in that: The first region includes first doped regions and second doped regions alternately arranged along the second direction; The step of forming the initial doping layer includes: forming an initial second doping layer on the first doping region, and forming an initial third doping layer on the second doping region; The step of forming the germanium-containing layer includes forming the germanium-containing layer on the second regions of both the initial second doping layer and the initial third doping layer.

13. A photovoltaic cell, characterized in that: include: A silicon substrate having a first surface and a second surface opposite to each other along a first direction, wherein the first surface comprises a plurality of first regions spaced apart along a second direction, the first direction being a thickness direction of the silicon substrate, and the second direction intersecting with the first direction; a doping layer located on the first region and containing silicon, wherein the surface of the doping layer away from the silicon substrate comprises at least one second region, and a germanium-silicon alloy layer is disposed on the second region of the doping layer; The gate line is at least located on a side of the germanium-silicon alloy layer away from the silicon substrate.

14. The photovoltaic cell according to claim 13, characterized in that: Also includes: The germanium-containing layer is located between the gate line and the germanium-silicon alloy layer.

15. The photovoltaic cell according to claim 13, characterized in that: The ratio of the content of germanium atoms to the content of silicon atoms in the germanium-silicon alloy layer is 0.1-10.

Images