Solar cell and method of manufacturing the same, stacked cell, and photovoltaic module

Abstract

The embodiment of the present application relates to the field of photovoltaics, and provides a solar cell, a preparation method thereof, a laminated cell and a photovoltaic module, the solar cell comprising: a silicon substrate comprising a first surface and a second surface opposite to each other, and a first side surface connecting the first surface and the second surface; a doped region on the first surface of the silicon substrate; and a doped conductive layer on the second surface of the silicon substrate, wherein the doped conductive layer comprises a second side surface, the roughness of the second side surface is greater than that of the first side surface, and the second side surface is located on the same side as the first side surface. In the solar cell, the first side surface is a relatively smooth surface with a shallow thermal damage layer, which is beneficial to the adhesion of a high-quality passivation film and can form an excellent composite passivation layer, and the second side surface is a rougher surface, the high-roughness second side surface provides a larger specific surface area and more dangling bond sites, which lays a physical foundation for subsequent selective deposition or doping.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to a solar cell and its preparation method, a tandem cell, and a photovoltaic module. Background Technology

[0002] As the photovoltaic industry pursues higher module power and lower levelized cost of electricity, existing technologies typically employ high-efficiency cell and module technologies. High-efficiency cell technologies, such as TOPCon (Tunneling Oxide Passivated Contact) technology, significantly improve the open-circuit voltage and conversion efficiency of cells through the excellent passivation performance of ultra-thin silicon oxide layers and doped polycrystalline silicon layers. Module technologies, such as cutting standard cells (usually 182mm or 210mm) into quarters or quintets, reduce internal current and resistance losses, improve the power generation capacity of modules under shading, and reduce the risk of hot spots.

[0003] However, when TOPCon cells are cut (especially laser-cut) to fabricate smaller cells, new, unpassivated silicon surfaces are created at the cut edges. These nascent sides introduce numerous dangling bonds and defects, becoming strong recombination centers for charge carriers (electrons and holes), severely negating the passivation advantages of TOPCon technology on both the front and back sides. Specifically, the open-circuit voltage and fill factor of the cut smaller cells are significantly lower than those of the entire cell.

[0004] In other words, when solar cells are cut (especially by laser cutting) to prepare smaller cells, new, unpassivated silicon surfaces are created at the cut edges. These newly formed sides introduce a large number of dangling bonds and defects, becoming strong recombination centers for charge carriers (electrons and holes), leading to a significant degradation in cell performance after cell slicing.

[0005] Existing technologies typically have the following problems in the solar cell slicing process:

[0006] 1. Poor process compatibility: Existing few side passivation technologies often require processing individual small pieces after cleaving, which is cumbersome. The additional passivation process steps are complicated and may be incompatible with existing TOPCon production lines, increasing costs and time.

[0007] 2. Limited passivation effect: Conventional four-slice process does not treat the cut sides or treats them simply. The high density of defects on the sides becomes a strong recombination center. Simple single-layer passivation film (such as only depositing aluminum oxide Al2O3) is not ideal in dealing with the highly active cut damage layer, resulting in a significant degradation of battery performance after slicing.

[0008] 3. Electrode contact issues: The passivation layer is usually an insulating layer. If the side is passivated, the insulating passivation layer will prevent the main grid electrode from forming an electrical connection with the side of the battery (which may be connected to the back field), affecting current collection.

[0009] To address the problem in existing battery cutting processes where high-density defects on the sides become strong recombination centers, leading to significant performance degradation after slicing, this application provides a solar cell and its preparation method, a tandem cell, and a photovoltaic module. Summary of the Invention

[0010] This application provides a solar cell, a method for preparing a solar cell, a tandem cell, and a photovoltaic module, which at least solves the problem in the prior art where high-density defects on the sides of the cell cutting process become strong recombination centers, leading to a significant degradation in cell performance after slicing.

[0011] According to some embodiments of this application, one aspect of this application provides a solar cell, including: a silicon substrate, including a first surface and a second surface opposite to each other, and a first side surface connecting the first surface and the second surface; a doped region located on the first surface of the silicon substrate; and a doped conductive layer located on the second surface of the silicon substrate, wherein the doped conductive layer includes a second side surface, the roughness of the second side surface is greater than the roughness of the first side surface, and the second side surface and the first side surface are located on the same side.

[0012] In some embodiments, the doped conductive layer includes a first doped conductive layer and a second doped conductive layer, wherein the first doped conductive layer is located on the side away from the second side and the second doped conductive layer is located on the side closer to the second side.

[0013] In some embodiments, the doping concentration of the first doped conductive layer is less than the doping concentration of the second doped conductive layer.

[0014] In some embodiments, the doping concentration of the first doped conductive layer is 2e 20 / cm - ³~3e 20 / cm - ³, the doping concentration of the second doped conductive layer is 6e 20 / cm - ³~8e 20 / cm - ³.

[0015] In some embodiments, the length of the second doped conductive layer in the first direction is 300 nm to 700 nm, and the first direction is the direction that intersects with the direction in which the second doped conductive layer points to the silicon substrate.

[0016] In some embodiments, the solar cell further includes: a first passivation layer located on one side of the first side surface, the first passivation layer including a first part and a second part, the first part being located on the first side surface and the second part being located on the second side surface, the second part including a plurality of grooves; and a conductive adhesive layer located on the side of the second part away from the silicon substrate and filling the grooves.

[0017] According to some embodiments of this application, another aspect of this application provides a method for fabricating a solar cell. The method is used to fabricate any of the aforementioned solar cells. The method includes: providing an initial cell, the initial cell comprising an initial substrate and an initial doped conductive layer, the initial substrate having opposing first and second surfaces, the initial doped conductive layer located on the second surface of the initial substrate; cutting the initial cell from the initial doped conductive layer along a cutting direction using a first cutting parameter, the cutting direction being a direction from the second surface of the initial substrate to the first surface of the initial substrate; and, if cutting reaches the initial substrate, continuing the cutting process along the cutting direction using a second cutting parameter to obtain a pre-treated cell comprising a doped conductive layer, a silicon substrate, and a doped region, the silicon substrate having a first side surface connecting the first surface and the second surface, the doped conductive layer including a second side surface, the roughness of the second side surface being greater than the roughness of the first side surface, and the second side surface being located on the same side as the first side surface.

[0018] In some embodiments, the first cutting parameter includes a first energy density of the laser, and the second cutting parameter includes a second energy density of the laser, wherein the first energy density is less than the second energy density.

[0019] In some embodiments, the first energy density is 0.1 J / cm³. 2 ~0.13J / cm 2 The second energy density is 0.5 J / cm³. 2 ~2.0J / cm 2 .

[0020] In some embodiments, the initial battery cell is further cut along the cutting direction using a second cutting parameter to obtain a pre-treated battery. This includes: during the process of further cutting the initial battery cell along the cutting direction using the second cutting parameter, a first doping gas is used to purge the first side surface so that the first side surface reacts with the first doping gas to obtain the pre-treated battery.

[0021] In some embodiments, after obtaining the pretreated battery, the fabrication method further includes: depositing a first passivation layer on the first side and the second side, the first passivation layer comprising a first part and a second part, the first part being located on the first side and the second part being located on the second side; patterning the second part to form a plurality of grooves in the second part; and injecting conductive adhesive into the grooves to obtain a solar cell.

[0022] In some embodiments, the doped conductive layer includes a first doped conductive layer and a second doped conductive layer, wherein the first doped conductive layer is located on the side away from the second side, the second doped conductive layer is located on the side closer to the second side, and the concentration of the doping gas in the second doped conductive layer is 1.2 to 1.3 times the concentration of the doping gas in the first doped conductive layer.

[0023] In some embodiments, the depth of the cutting process is less than or equal to the length of the initial battery cell in the cutting direction.

[0024] According to some embodiments of this application, another aspect of this application provides a stacked battery, including: a bottom battery, which is any of the solar cells described above; and a top battery, located on the bottom battery.

[0025] According to some embodiments of this application, another aspect of this application provides a photovoltaic module, including: a battery string, which is formed by connecting multiple solar cells, wherein the solar cells include any of the solar cells described above, or are formed by connecting multiple solar cells prepared by any of the methods described above, or are formed by connecting multiple stacked cells described above; an encapsulating film for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulating film facing away from the battery string.

[0026] The technical solution provided in this application has at least the following advantages: The cut side surface (i.e., the first side surface) of the silicon substrate of the solar cell is a smooth surface with a shallow thermal damage layer. This surface is conducive to the formation of a dense, uniform, and defect-free thin film of the subsequently deposited passivation material. This high-quality passivation layer can effectively saturate the dangling bonds on the silicon surface and significantly reduce the surface state density. The cut side surface (i.e., the second side surface) of the doped conductive layer is a rough surface. This surface significantly increases the specific surface area of ​​the sidewall, providing more attachment points and mechanical anchoring points for subsequent conductive materials or doped layers. This not only enhances the mechanical strength of the electrical connection and prevents solder ribbon detachment but also increases the effective contact area, thereby reducing contact resistance. This solves the problem in the prior art where high-density defects on the side surface become strong recombination centers, leading to significant performance degradation of the cell after slicing. Attached Figure Description

[0027] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the drawings in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this application or in the conventional art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 A schematic cross-sectional view of a solar cell provided in an embodiment of this application is shown;

[0029] Figure 2 A cross-sectional schematic diagram of another solar cell provided in an embodiment according to this application is shown;

[0030] Figure 3 A schematic flowchart of a method for preparing a solar cell according to an embodiment of this application is shown;

[0031] Figure 4 A schematic cross-sectional view of an initial battery cell provided in an embodiment according to this application is shown;

[0032] Figure 5 It shows in Figure 4 A cross-sectional view of the initial solar cell after cutting the initial doped conductive layer using the first cutting parameter.

[0033] Figure 6 It shows in Figure 5 A cross-sectional view of the pretreated battery after cutting the initial substrate using the second cutting parameters;

[0034] Figure 7 It shows in Figure 6 A cross-sectional view of the pretreated battery after the first passivation layer is formed on the basis of the above.

[0035] Figure 8 It shows in Figure 7 A cross-sectional view of a solar cell after it has been split.

[0036] Figure 9 A cross-sectional structural schematic diagram of a stacked battery provided in an embodiment of this application is shown;

[0037] Figure 10 A cross-sectional structural schematic diagram of a photovoltaic module provided in an embodiment of this application is shown.

[0038] The above figures include the following reference numerals:

[0039] 10. Initial solar cell; 11. Initial substrate; 12. Initial doped region; 13. Initial doped conductive layer; 20. Solar cell; 21. Silicon substrate; 22. Doped region; 23. Doped conductive layer; 231. First doped conductive layer; 232. Second doped conductive layer; 24. First passivation layer; 241. First part; 242. Second part; 31. First side; 32. Second side; 41. Bottom cell; 42. Top cell; 50. Encapsulating film; 51. Cover plate; 52. Conductive strip. Detailed Implementation

[0040] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0041] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0042] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0043] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0044] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0045] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0046] In the accompanying drawings corresponding to the embodiments of this application, the thickness and area of ​​the layers are enlarged for better understanding and ease of description. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component may be "directly" located on the surface of the other component, or there may be a third component between the two components. Conversely, when describing a component on the surface of another component, or when another component is formed or disposed on the surface of a component, it indicates that there is no third component between the two components. Furthermore, when describing a component as being "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0047] In the description of the embodiments of this application, when a component "includes" another component, other components are not excluded unless otherwise stated, and other components may be further included. Furthermore, when a component such as a layer, film, region, or plate is referred to as being "on / located" on another component, it can be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or another component may be present therein. Moreover, 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 indicates that no other components are located therein.

[0048] The terminology used in the description of the various embodiments described herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims, the term "foreword" is also intended to include the plural form unless the context clearly indicates otherwise. Components include layers, films, regions, or plates, etc.

[0049] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0050] Figure 1 This is a cross-sectional schematic diagram of a solar cell according to an embodiment of this application. Figure 1 As shown, the solar cell includes: a silicon substrate 21, including a first surface and a second surface opposite to each other, and a first side surface 31 connecting the first surface and the second surface; a doped region 22 located on the first surface of the silicon substrate 21; and a doped conductive layer 23 located on the second surface of the silicon substrate 21, wherein the doped conductive layer 23 includes a second side surface 32, the roughness of the second side surface 32 is greater than the roughness of the first side surface 31, and the second side surface 32 and the first side surface 31 are located on the same side.

[0051] The solar cells fabricated from the aforementioned solar cells are TOPCon cells. The first side is mainly a complete passivation region to ensure the cell's on-state voltage and is designed as a passivation functional region; the second side is a rough and heavily doped region that serves as a current collection function and is designed as a connection functional region.

[0052] The aforementioned first side surface is smooth and has a shallow thermal damage layer, which is beneficial for the subsequent deposition of passivation materials (such as Al2O3, SiN). x This process forms a dense, uniform, and defect-free thin film. This high-quality passivation layer effectively saturates the dangling bonds on the silicon surface, significantly reducing the surface state density. Due to the low number of surface defects, the interface quality between the passivation layer and the silicon substrate is high, thereby greatly suppressing the nonradiative recombination of electrons and holes on the sidewall surfaces. This directly increases the open-circuit voltage of the cell, offsetting the edge recombination losses caused by dicing. Furthermore, the complete passivation layer formed on the smooth sidewalls has good insulation properties, preventing lateral leakage and ensuring that the current mainly flows out along the designed path (i.e., through the second side), thus guaranteeing the stability of electrical performance.

[0053] The aforementioned second side has a rough structure, which significantly increases the specific surface area of ​​the sidewall, providing more attachment points and mechanical anchoring points for subsequent conductive materials (such as conductive adhesives and solders) or doped layers. This not only enhances the mechanical strength of the electrical connection and prevents solder ribbon detachment but also increases the effective contact area, thereby reducing contact resistance. Rough surfaces are typically accompanied by more dangling bonds and defect sites, which are more prone to chemical reactions or atomic implantation during laser-assisted doping or reactive gas processing. This allows the second side to form a high-concentration doped region (such as an n+ or p+ layer), thereby reducing the sheet resistance of this region and forming a good ohmic contact window. In subsequent deposition processes, the rough surface can lead to a loose or porous growth of passivation films (such as Al2O3) or make them easier to selectively remove (such as through laser ablation of SiN). x ).

[0054] Specifically, the first side of this application achieves extreme passivation through a smooth structure, protecting the battery edge from leakage and recombination; the second side achieves efficient conductivity through a rough structure, ensuring smooth current conduction.

[0055] In the solar cell described in this application, the cut side of the silicon substrate (i.e., the first side) is a smooth surface with a shallow thermal damage layer. This surface facilitates the formation of a dense, uniform, and defect-free thin film of the subsequently deposited passivation material. This high-quality passivation layer can effectively saturate the dangling bonds on the silicon surface, significantly reducing the surface state density. The cut side of the doped conductive layer (i.e., the second side) is a rough surface. This surface significantly increases the specific surface area of ​​the sidewalls, providing more attachment points and mechanical anchoring points for subsequent conductive materials or doped layers. This not only enhances the mechanical strength of the electrical connection and prevents solder ribbon detachment but also increases the effective contact area, thereby reducing contact resistance. This solves the problem in existing cell cutting processes where high-density defects on the sides become strong recombination centers, leading to significant performance degradation of the cells after slab preparation.

[0056] In some embodiments, such as Figure 1 and Figure 2 As shown, the doped conductive layer 23 includes a first doped conductive layer 231 and a second doped conductive layer 232. The first doped conductive layer 231 is located on the side away from the second side surface 32, and the second doped conductive layer 232 is located on the side close to the second side surface 32.

[0057] In the above embodiment, the doped conductive layer located on the side is laterally divided into two regions with different electrical or physical properties: a first doped conductive layer away from the side contact point and a second doped conductive layer closer to the side contact point. This partitioning design is based on the physical principles of carrier transport and contact resistance formation. By setting different doping distributions or interface characteristics at different lateral positions, the local area near the sidewall has specific electrical properties to form a good ohmic contact with the conductive connection material on the side, while the main area away from the sidewall maintains the standard battery back surface characteristics.

[0058] This structure enables precise control of the connection path between the back electrode and the sides. By functionally partitioning the conductive layer laterally, it ensures that conductive channels are formed on the sides without compromising the optical reflection and carrier collection efficiency of the main back electrode area. This optimized structure effectively reduces lateral contact resistance, ensuring smooth current conduction from the battery interior through the sides to the solder ribbon or conductive adhesive, while avoiding increased leakage current or decreased passivation effect caused by high doping across the entire side, thus improving the overall fill factor of the battery.

[0059] In some embodiments, the doping concentration of the first doped conductive layer is lower than the doping concentration of the second doped conductive layer.

[0060] The above embodiments utilize the influence of doping concentration on carrier concentration and contact barrier in semiconductor physics. The first doped conductive layer has a low doping concentration, while the second doped conductive layer near the side has a high doping concentration. High doping concentration significantly reduces the Schottky barrier width at the metal / semiconductor or conductive adhesive / semiconductor interface, promoting tunneling and thus reducing contact resistance. Low doping concentration, on the other hand, helps maintain good bulk material quality and reduce surface recombination. This achieves a balance between low contact resistance and high passivation. The higher lateral doping concentration ensures high-quality ohmic contact between the conductive adhesive or solder ribbon and the battery back surface, greatly reducing series resistance. The lower bulk doping concentration helps reduce non-radiative recombination centers, maintaining a higher open-circuit voltage. This differentiated doping distribution results in extremely low contact impedance at the side connections while maintaining excellent passivation performance in non-connection areas, thereby improving module power while avoiding efficiency losses due to improper side processing.

[0061] In some embodiments, the doping concentration of the first doped conductive layer is 2e. 20 / cm - ³~3e 20 / cm - ³, for example: 2e 20 / cm - ³、2.2e 20 / cm - ³、2.5e 20 / cm - ³、2.7e 20 / cm - ³、3e 20 / cm - ³; The doping concentration of the second doped conductive layer is 6e. 20 / cm - ³~8e 20 / cm - ³, for example: 6e 20 / cm - ³、6.5e 20 / cm - ³、7e 20 / cm - ³、7.5e 20 / cm - ³、8e 20 / cm - ³.

[0062] For the first doped conductive layer, 2e 20 / cm - ³~3e 20 / cm -A concentration of ³ is sufficient to provide the necessary conductivity; for the second doped conductive layer, 6e 20 / cm - ³~8e 20 / cm - The high concentration of ³ ensures extremely low contact resistance because the higher carrier concentration more effectively shields the electric field, forming an ideal p-type ohmic contact. This range has been verified through simulation and field testing, aiming to maximize lateral conductivity and minimize contact resistance. The specific numerical range ensures the stability and consistency of battery performance, avoiding poor contact due to excessively low doping concentration or lattice damage and increased leakage current due to excessively high concentration. In actual production, adhering to this concentration range can stably achieve low contact resistance and good lateral current harvesting capability, thereby ensuring the current uniformity and overall conversion efficiency of the quad-cell cells in the module.

[0063] In some embodiments, the length of the second doped conductive layer 232 in the first direction is 300nm to 700nm, for example: 300nm, 350nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm, and the first direction is the direction that intersects with the direction of the second doped conductive layer 232 pointing to the silicon substrate 21.

[0064] In some embodiments, the first direction is perpendicular to the direction in which the second doped conductive layer points towards the silicon substrate. Since the second doped conductive layer is simultaneously injected with a precursor atmosphere containing dopant elements (such as phosphorus) during the dicing process to achieve in-situ doping and activation of localized sidewall regions using laser thermal effects, the depth of dopant injection is limited. A length of 300nm to 700nm ensures sufficient physical contact area to carry the module's operating current while avoiding excessively wide areas that would occupy too much effective cell area or add unnecessary lateral doping process time. This moderate doping depth ensures that the conductive adhesive or solder ribbon can completely cover and contact the highly doped region, forming a reliable electrical connection, while avoiding increased sidewall passivation difficulty or uncontrolled impurity diffusion due to excessively large areas. This precise dimensional control allows the cell to maintain high efficiency while having a higher tolerance for subsequent stringing or alignment accuracy, reducing the risk of alignment errors during production and improving yield.

[0065] In some embodiments, in the first direction, the depth of the second doped conductive layer is 80% to 90% of the total depth of the doped conductive layer.

[0066] In some embodiments, such as Figure 1 and Figure 2As shown, the solar cell further includes: a first passivation layer 24, which is located on one side of the first side surface 31. The first passivation layer 24 includes a first part 241 and a second part 242. The first part 241 is located on the first side surface 31, and the second part 242 is located on the second side surface 32. The second part 242 includes multiple grooves; a conductive adhesive layer ( Figure 2 (not shown in the image), the conductive adhesive layer is located on the side of the second part 242 away from the silicon substrate 21 and fills the groove.

[0067] The above embodiment achieves "self-aligned" contact by forming a composite passivation layer with a groove pattern on the sidewall and filling these grooves with conductive adhesive. A first passivation layer covers the entire sidewall to provide passivation, but grooves are formed near the back contact area (second sidewall), exposing the underlying conductive material or highly active surface. After the conductive adhesive fills the grooves, it directly connects to the internal conductive layer, while the passivation layer covering the remaining portion acts as insulation and passivation, preventing lateral leakage and carrier recombination. The conductive adhesive filling the grooves not only ensures good electrical contact but also enhances mechanical strength through the volume effect of the adhesive, improving the adhesion between the solder ribbon and the battery sidewall. This structure effectively isolates the passivation layer from direct contact with the conductive adhesive, avoiding damage to passivation performance from the conductive adhesive, while ensuring the overall passivation effect of the sidewall, significantly improving the battery's open-circuit voltage and fill factor.

[0068] In addition, a second passivation layer is provided on the side of the doped region away from the silicon substrate, and a third passivation layer is provided on the side of the doped conductive layer away from the silicon substrate.

[0069] Embodiments of this application also provide a method for preparing a solar cell, such as... Figures 3 to 8 As shown, the above preparation method is used to prepare any of the above-mentioned solar cells, and the preparation method includes the following steps:

[0070] Step S101, provide the initial battery cell 10, and obtain as follows Figure 4 The structure shown above, the initial cell 10 includes an initial substrate 11 and an initial doped conductive layer 13, the initial substrate 11 having opposing first and second surfaces, and the initial doped conductive layer 13 located on the second surface of the initial substrate 11.

[0071] Among them, such as Figure 4As shown, the initial solar cell 10 also includes an initial doped region 12. The first surface is generally the front side of the cell, and the second surface is generally the back side of the cell. In the early stages of cell fabrication, impurity atoms (such as phosphorus P for N-type or boron B for P-type) are introduced into the silicon substrate surface at a specific depth using high-temperature diffusion or ion implantation techniques. In a TOPCon structure, the initial doped region typically refers to the N-type emitter region below the front antireflection layer (if it is a PERC / TOPCon back passivation structure) or, in a heterojunction structure, the doped layer below the TCO layer. In a TOPCon cell, the initial doped conductive layer typically consists of an ultrathin tunneling oxide layer (SiOx) and a heavily doped polycrystalline silicon layer (Poly-Si). The initial doped conductive layer allows photogenerated carriers (electrons or holes) to pass through the tunneling oxide layer to the polycrystalline silicon layer and then be transported to the metal electrode (solder ribbon / conductive adhesive).

[0072] In some embodiments, the initial solar cell comprises a front passivation antireflection layer, a back tunneling oxide layer, and a doped polycrystalline silicon layer (i.e., a TOPCon structure) in the fabrication of a solar cell substrate. The doped polycrystalline silicon layer includes an initial substrate, an initial doped region, and an initial doped conductive layer.

[0073] Step S102: Using the first cutting parameters, the initial battery cell 10 is cut from the initial doped conductive layer 13 along the cutting direction to obtain the following... Figure 5 The structure shown above has a cutting direction that points from the second surface of the initial substrate 11 to the first surface of the initial substrate 11.

[0074] In this design, the initial doped conductive layer is a back-side n+ doped polysilicon layer. In some embodiments, when scanning to the lower region of the sidewall (corresponding to the back-side n+ doped polysilicon layer or the region that needs to be connected to the back field, i.e., the initial doped conductive layer), a first cutting parameter is used. This parameter employs defocusing, reduced energy density, or an auxiliary reactive gas (such as SF6) to form a micro / nano rough structure, significantly increasing the specific surface area and altering the film nucleation behavior. Furthermore, a precursor atmosphere containing doped elements (such as phosphorus) is simultaneously injected into the laser-acting region to achieve in-situ doping and activation of the local sidewall region using the laser thermal effect, thereby reducing the sheet resistance of that region.

[0075] Step S103: After cutting to the initial substrate 11, the initial solar cell 10 is further cut along the cutting direction using the second cutting parameters to obtain a pre-treated solar cell including a doped conductive layer 23, a silicon substrate 21, and a doped region 22, as shown in the figure. Figure 1 The structure shown has a silicon substrate having a first side surface connecting the first surface and the second surface, and a doped conductive layer including a second side surface. The roughness of the second side surface 32 is greater than that of the first side surface 31, and the second side surface 32 and the first side surface 31 are located on the same side.

[0076] In some embodiments, the battery cell can be directly cut in step S103 to obtain, as shown below. Figure 1 The structure shown can also be achieved without completely cutting the solar cells, resulting in a structure like this. Figure 6 The structure shown.

[0077] In some embodiments, when scanning to the upper sidewall region (i.e., the initial substrate), a second cutting parameter (such as higher energy density, short pulse) is used to obtain a relatively smooth surface with a shallow thermal damage layer, which is conducive to the adhesion of a high-quality passivation film.

[0078] In the laser-cut solar cell step described in the above embodiments, by controlling the laser parameters (i.e., the first cutting parameter and the second cutting parameter), different regions (i.e., the first side and the second side) of the cut channel sidewall are actively and differentially treated. This results in predetermined differences in the surface morphology, chemical composition, or defect states of the first and second side surfaces, laying the foundation for differentiated results in subsequent single processes. Then, utilizing the surface state differences caused by the above pretreatment, the same standard passivation layer (such as Al2O3 / SiN) is applied. x During the deposition process, the intrinsic growth characteristics of the deposited film on substrates with different properties are utilized to form an insulating passivation film and a transitional / conductive contact window in different regions of the sidewall. That is, an insulating passivation film is formed on the first side and a conductive contact window is formed on the second side.

[0079] The above embodiments begin by cutting the battery from the back, transforming the cut sidewalls from a passive process endpoint into an active functional design platform. Through parameter control of the front-end laser process, the battery cell is cut to form a first and second sidewall with different characteristics, thus implanting a hidden functional pattern into the sidewalls—that is, the first and second sidewalls have different properties. Then, using the back-end thin-film process to respond to the differentiated responses of the different sidewalls, a patterned composite structure is fabricated in one step. Finally, with this structure, precise electrode interconnection is achieved with minimal process overhead.

[0080] In other words, the above embodiments utilize parameter switching during the laser cutting process to achieve differentiated modification of the sidewall surface state in a single processing step. By using a first cutting parameter to treat the initial doped conductive layer in the first stage, and switching to a second cutting parameter to treat the silicon substrate in the second stage, the sidewalls at different depths are modified by varying laser energy, pulse width, or auxiliary gas to form different morphologies (such as roughness differences) or chemical states. This "dynamically modulated" laser process allows functionally differentiated micro-regions to naturally form on the upper and lower parts of the sidewalls within the same cutting process.

[0081] The above embodiments significantly simplify the sidewall processing technology, achieving "one laser, multiple functions." No additional sidewall passivation or modification steps are required after cutting, reducing equipment investment and production costs. Precise control of laser parameters allows for flexible adjustment of sidewall roughness and doping state, adapting to the needs of different materials and battery structures. This integrated process not only improves production efficiency but also reduces the risk of microcracks in batteries caused by repeated handling and processing, enhancing product reliability.

[0082] The method for fabricating the solar cell described in this application first provides an initial solar cell, which includes an initial substrate and an initial doped conductive layer. The initial substrate has a first surface and a second surface opposite to each other, and a first side surface connecting the first surface and the second surface. The initial doped conductive layer is located on the second surface of the initial substrate. Then, the initial solar cell is cut along a cutting direction from the initial doped conductive layer using a first cutting parameter, with the cutting direction pointing from the second surface of the initial substrate to the first surface. Finally, after cutting to the initial substrate, the initial solar cell is further cut along the cutting direction using a second cutting parameter to obtain a pre-treated solar cell including a doped conductive layer, a silicon substrate, and doped regions. The roughness of the second side surface is greater than that of the first side surface, and the second side surface is located on the same side as the first side surface. This fabrication method, through control of the cutting parameters, forms a smooth first side surface with a shallow thermal damage layer and a rough second side surface. The first side surface facilitates the formation of a dense, uniform, and defect-free thin film of the subsequently deposited passivation material. This high-quality passivation layer can effectively saturate the dangling bonds on the silicon surface, significantly reducing the surface state density. The second side has a rough surface, which significantly increases the specific surface area of ​​the sidewall, providing more attachment points and mechanical anchoring points for subsequent conductive materials or doped layers. This not only enhances the mechanical strength of the electrical connection and prevents solder ribbon detachment, but also increases the effective contact area, thereby reducing contact resistance. This solves the problem in existing battery cutting processes where high-density defects on the side become strong recombination centers, leading to significant performance degradation of the battery after slicing.

[0083] In some embodiments, the first cutting parameter includes a first energy density of the laser, the second cutting parameter includes a second energy density of the laser, and the first energy density is less than the second energy density.

[0084] The above embodiments control the thermal and non-thermal effects of laser-material interaction by regulating the laser energy density. A lower first energy density aims to remove or modify the material without causing excessive damage or excessively high temperatures; a higher second energy density aims to induce more vigorous material reactions, such as increased defect generation, formation of micro / nano structures, or activation of the assist gas. This stepwise change in energy density is the direct cause of the differences in physicochemical properties between the upper and lower regions of the sidewall.

[0085] By setting a clear energy density difference, a smooth or low-damage layer conducive to passivation is formed on the upper sidewall, while a highly active or high-roughness layer conducive to conductivity is formed on the lower sidewall. The controllability of this parameter range makes the process highly repeatable, enabling the stable production of solar cells that meet design requirements, laying a solid foundation for subsequent high-quality passivation and low-resistance contacts.

[0086] In some embodiments, the first cutting parameter further includes the first pulse width of the laser, and the second cutting parameter further includes the second pulse width of the laser, wherein both the first pulse width and the second pulse width are 10ps to 20ps.

[0087] In some embodiments, the first energy density is 0.1 J / cm³. 2 ~0.13J / cm 2 For example: 0.1 J / cm 2 0.11J / cm 2 0.12J / cm 2 0.13J / cm 2 The aforementioned second energy density is 0.5 J / cm³. 2 ~2.0J / cm 2 For example: 0.5J / cm 2 0.7J / cm 2 0.8J / cm 2 1.0 J / cm 2 1.2J / cm 2 1.5J / cm 2 1.7J / cm 2 1.8J / cm 2 2.0 J / cm 2 .

[0088] The above embodiments are based on experimental measurements of the absorption coefficient, ablation threshold, and heat-affected zone (HAZ) characteristics of silicon and doped silicon materials using lasers of specific wavelengths (such as ultraviolet or infrared). Low energies of 0.1–0.13 J / cm² are sufficient to remove the surface layer or produce slight modifications without damaging the bulk, while high energies of 0.5–2.0 J / cm² are sufficient to induce significant surface reconstruction or dopant gas reactions. This range was derived through extensive experimental design optimization to balance processing quality and efficiency. This control of energy density ensures process stability and consistent battery performance. The specific energy range avoids problems such as insufficient modification due to too low energy or large-area sidewall damage and microcrack propagation due to too high energy. Operating within this range allows for precise control of sidewall roughness and defect density, thereby ensuring the quality of the passivation film and the stability of contact resistance, minimizing the dispersion of battery efficiency in mass production.

[0089] In some embodiments, the initial battery cell 10 is further cut along the cutting direction using a second cutting parameter to obtain a pre-treated battery. This includes: during the process of further cutting the initial battery cell 10 along the cutting direction using the second cutting parameter, the first doping gas is used to purge the first side surface 31 so that the first side surface 31 reacts with the first doping gas to obtain the pre-treated battery.

[0090] The first doping gas includes a p-type dopant, such as PH3, at 1000-2000 sccm. During laser cutting, the gas containing the dopant element (such as boron or phosphorus) is purged, utilizing the localized high temperature or plasma effect generated by the laser to inject or activate dopants onto the sidewall surface. This in-situ doping technique utilizes the thermal gradient or chemical activity of the laser to form a high-concentration doped layer in the lower region of the sidewall, thereby reducing the resistivity of that region. The direction and timing of the gas purging are precisely controlled to ensure that doping occurs only in the predetermined sidewall region.

[0091] The above embodiments achieve simultaneous active enhancement of sidewall conductivity and morphology modification. Through in-situ doping, a low-resistance conductive channel is formed in the lower part of the sidewall, eliminating the need for subsequent diffusion or ion implantation processes and simplifying the process. Simultaneously, the synergistic effect of laser and gas further optimizes the surface morphology, increases the specific surface area, and enhances the adhesion of the passivation film or the wettability of the conductive adhesive. This integrated "processing-modification-doping" method significantly improves the electrical performance of the battery sidewalls and reduces manufacturing costs.

[0092] In some embodiments, such as Figure 2 , Figures 6 to 8 As shown, after obtaining the pretreated battery described above, the preparation method further includes the following steps:

[0093] Step S201: Deposit a first passivation layer 24 on the first side surface 31 and the second side surface 32 to obtain the following... Figure 7 The structure shown is as follows: Figure 2 As shown, the first passivation layer 24 includes a first part 241 and a second part 242, the first part 241 being located on the second side surface 32 and the second part 242 being located on the first side surface 31.

[0094] Step S202: The second part 242 is patterned to form multiple grooves in the second part 242, resulting in... Figure 2 The structure shown;

[0095] Step S203: Inject conductive adhesive into the groove to obtain a solar cell.

[0096] Specifically, a passivation film is deposited on the treated solar cells. Due to the significant differences in surface conditions between the first side and the second side, Al₂O₃ (or SiO₂) is deposited on the first side (smooth, low-damage) using PECVD / ALD. x ) / SiN x Stacked layers can grow densely and uniformly, forming an excellent composite passivation layer. On the second side (rough or doped), the deposited initial layer (such as Al2O3) may exhibit a porous and loose morphology, or form different chemical bonding states with the substrate, resulting in changes in its insulation, density, or adhesion.

[0097] A simplified patterning process is applied to the second side, for example, by irradiating the lower part of the cut path with a wide-spot or scanning ultraviolet or infrared laser. This process can be specifically targeted at the film layer on the second side: causing the porous Al2O3 to further crystallize and shrink, generating through-cracks; or utilizing SiN... x Due to the difference in laser absorption rate between the modified silicon layer below and the modified silicon layer, the SiN on the second side surface is selectively ablated and removed. x The layer exposes the underlying modified silicon layer or n+ polysilicon layer without affecting the complete passivation layer on the first side.

[0098] The above embodiments utilize the growth differences or selective removal techniques of deposited thin films on substrates with different surface properties to form a patterned passivation layer structure. After depositing the first passivation layer, grooves are formed in the region near the side (second part) using physical or chemical methods (such as laser ablation or wet etching) to expose the underlying conductive layer. Conductive adhesive is then injected, and the grooves are filled using capillary action or leveling to achieve electrical connection. This process relies on the surface state differences created by the previous laser modification. This achieves precise spatial separation and reliable connection between passivation and conductivity. The patterning process ensures the passivation layer remains intact in non-contact areas, providing excellent passivation; while the grooves formed in the contact areas ensure direct, large-area contact between the conductive adhesive and the internal conductive layer, reducing contact resistance. The conductive adhesive filling not only provides electrical connection but also enhances mechanical strength and prevents solder ribbon detachment. This structural design effectively solves the problems of side leakage and poor contact, improving the overall performance of the battery.

[0099] Based on the first and second sides, during component stringing, the connecting material (conductive adhesive or solder ribbon) can achieve precise and low-damage connection with the internal conductive layer of the battery by virtue of its physicochemical properties (such as wettability) or through a simple patterning process (such as treating only specific modified areas), perfectly resolving the spatial contradiction between passivation and conductivity.

[0100] In addition, such as Figure 7 and Figure 8 As shown, if the solar cell is not completely cut during the cutting process, the solar cell is cleaved after the first passivation layer 24 is deposited, resulting in the following: Figure 8 The structure shown is patterned after fracking to obtain the following result: Figure 2 The structure shown is as follows. The battery cells are split into individual quarter cells. Each cell has a pre-defined patterned functional structure on its side.

[0101] The next step is the component stringing process, where the connecting material (conductive adhesive or solder ribbon) is placed horizontally along the side of the battery corresponding to the second side. This includes two processes: self-alignment mechanism one and self-alignment mechanism two.

[0102] Using a self-alignment mechanism (if a contact window has been formed on the second side): the connecting material directly forms an ohmic contact with the internal conductive layer through the contact window. The complete passivation layer on the first side naturally provides insulation and passivation.

[0103] The second self-alignment mechanism allows for a low-temperature heat treatment or light treatment of only the second side after the conductive adhesive is applied. This enables the active ingredients in the conductive adhesive to selectively react with the silicon material under the second side to form contact, without affecting the first side.

[0104] The above steps enable reliable electrical connections on the sides without the need for high-precision alignment photolithography or precision printing.

[0105] In some embodiments, such as Figure 2 As shown, the doped conductive layer 23 includes a first doped conductive layer 231 and a second doped conductive layer 232. The first doped conductive layer 231 is located on the side away from the second side surface 32, and the second doped conductive layer 232 is located on the side close to the second side surface 32. The concentration of the doping gas in the second doped conductive layer 232 is 1.2 to 1.3 times the concentration of the doping gas in the first doped conductive layer 231.

[0106] By controlling the dynamic changes in the precursor gas flow rate, a gradient distribution of lateral doping concentration can be achieved. During the cutting or deposition process, the concentration of the dopant gas is adjusted to achieve a higher doping concentration in areas near the sides, while maintaining a lower concentration in areas farther from the sides. This fine-tunes the uniformity of lateral electrical performance and contact quality. Precise concentration ratio control ensures that the conductivity of the sidewall contact area meets requirements, while avoiding unstable contact resistance caused by excessive concentration fluctuations. This precise doping control enables the cells to maintain stable electrical performance across different batches and sizes, improving product consistency and yield, and providing process assurance for the large-scale production of high-efficiency modules.

[0107] In some embodiments, the depth of the cutting process is less than or equal to the length of the initial battery cell in the cutting direction.

[0108] This design limits the range of cutting depth to ensure that laser cutting only penetrates the doped conductive layer and part of the silicon substrate, without completely severing the solar cell, thus preserving sufficient mechanical strength for subsequent dicing or transportation. Cutting depths less than or equal to the cell thickness aim to create a predetermined stress concentration line or modified layer, preparing for subsequent mechanical dicing while maintaining the integrity of the sidewall structure. This depth control is crucial to preventing the solar cell from breaking or developing uncontrollable cracks during processing.

[0109] The above embodiments ensure the structural integrity of the solar cell and the operability of subsequent processing. Appropriate cutting depth allows the solar cell to maintain its integrity while its sidewalls have undergone functionalization. During subsequent dicing, the solar cell can break neatly along the predetermined cutting line, reducing edge damage. This depth control also ensures that the modified sidewall areas and passivation layer remain intact and effective after dicing, avoiding internal structural damage or performance degradation caused by excessive cutting depth.

[0110] To enable those skilled in the art to better understand the technical solution of this application, the implementation process of the solar cell fabrication method of this application will be described in detail below with reference to specific embodiments.

[0111] This embodiment relates to a specific method for fabricating a solar cell, including the following steps:

[0112] Step S1: Use an ultraviolet picosecond laser with adjustable pulse energy. During scanning of the cutting path, adjust the energy in real time via an acousto-optic modulator. Use 1.5 μJ / pulse in the upper region and switch to 0.8 μJ / pulse in the lower region, while opening the side-blowing valve to inject a trace amount of PH3 vapor to achieve localized p-type doping.

[0113] Step S2: At 400°C, 10nm Al2O3 and 80nm SiN are sequentially deposited in the same PECVD chamber. x Then, a 308nm excimer laser beam was used to scan only the lower edge of the cut line on the back of the solar cell (corresponding to the second side), with an energy density set to 150mJ / cm², which was just enough to ablate SiN. x It reacts with Al2O3 to form a locally conductive phase without damaging the silicon substrate.

[0114] Step S3: Using a standard stringer, the solder strip position is referenced to the back edge of the battery. During soldering, the heat causes the solder to wet only the laser-treated, active second side, forming a strong contact.

[0115] Comparative Example 1

[0116] The initial solar cell is cut using a set of cutting parameters A, and the cut sides are not passivated after cutting. The resulting solar cell has an efficiency η of 27.42%, an open-circuit voltage of 0.74V, a short-circuit current of 4.09A, and a fill factor of 87%.

[0117] Comparative Example 2

[0118] The initial solar cell is cut using a set of cutting parameters A, and the cut sides of the initial solar cell are fully passivated (i.e., the passivation treatment is the same on the entire side). The resulting solar cell has an efficiency η of 27.7%, an open-circuit voltage of 0.744V, a short-circuit current of 4.12A, and a fill factor of 87.8%.

[0119] Example

[0120] The initial solar cell was cut from the back side. When cutting to the initial doped conductive layer, a laser with an energy density of 0.8 μJ / pulse and a pulse width of 10-20 ps was used, and a small amount of PH3 vapor was injected through a side-blowing valve to achieve local p-type doping, obtaining the second side. Then, when cutting to the initial substrate, a laser with an energy density of 1.5 μJ / pulse and a pulse width of 10-20 ps was used to obtain the first side. Subsequently, 10 nm of Al2O3 and 80 nm of SiN were sequentially deposited in the same PECVD chamber at 400°C. x Then, a 308nm excimer laser beam was used to scan only the lower edge of the cut line on the back of the solar cell (corresponding to the first side), with an energy density set to 150mJ / cm², for patterning. The resulting solar cell had an efficiency η of 27.86%, an open-circuit voltage of 0.746V, a short-circuit current of 4.14A, and a fill factor of 88.2%.

[0121] Table 1 is a parameter comparison table of Comparative Example 1, Comparative Example 2 and the Example, as shown in Table 1:

[0122] Table 1. Parameter Comparison Table

[0123]

[0124] According to some embodiments of this application, another aspect of this application provides a stacked battery, such as... Figure 9 As shown, it includes: a bottom cell 41, which is the solar cell described above, or a solar cell prepared by the method described above; and a top cell 42, located on the bottom cell 41.

[0125] In the above embodiments, the top cell 42 may include: a stacked first transport layer, a perovskite substrate, a second transport layer, a transparent conductive layer, and an antireflection layer. The first transport layer is directly opposite the bottom cell 41. In one example, the back side of the solar cell serving as the bottom cell 41, where a first doped semiconductor layer is disposed, is closer to the first transport layer in the top cell 42; in other words, the top cell 42 is located on the back side of the photovoltaic cell serving as the bottom cell 41.

[0126] In some embodiments, the first transport layer can be either an electron transport layer or a hole transport layer, and the second transport layer can be either an electron transport layer or a hole transport layer. For example, the first transport layer is an electron transport layer and the second transport layer is a hole transport layer, or the first transport layer is a hole transport layer and the second transport layer is an electron transport layer.

[0127] According to some embodiments of this application, another aspect of this application provides a photovoltaic module, such as... Figure 10As shown, the system includes: a battery string, which is formed by connecting multiple solar cells 20 as described above, or by connecting multiple solar cells 20 prepared by the above-described method, or by connecting multiple stacked cells; an encapsulating film 50 for covering the surface of the battery string; and a cover plate 51 for covering the surface of the encapsulating film 50 facing away from the battery string. The solar cells 20 can be electrically connected to each other via conductive strips 52, which are welded to the electrodes on the solar cells 20.

[0128] The aforementioned encapsulating film can be an organic encapsulating film such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate copolymer (EVA) film, polyvinyl octene elastomer (POE) film, or polyethylene terephthalate (PET) film. Alternatively, at least one of the first or second encapsulating layer can also be an EP film, EPE film, or PVP film. Specifically, EP film refers to a co-extruded film composed of stacked EVA and POE films; EPE film refers to a co-extruded film formed by sequentially stacking EVA, POE, and EVA films; and PVP film refers to a co-extruded film formed by stacking POE, EVA, and POE films. The co-extruded film can be manufactured by sequentially extruding one or more raw materials onto another pre-made film during the film processing, or by bonding different types of pre-made films together.

[0129] The aforementioned cover plate can be a glass cover plate, a plastic cover plate, or other cover plate with light-transmitting function. Specifically, the surface of the cover plate facing the encapsulating film can be an uneven surface or a textured surface containing multiple raised structures, which can increase the utilization rate of incident light.

[0130] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of this application. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A solar cell, characterized in that, The solar cell includes: A silicon substrate includes opposing first and second surfaces, and a first side surface connecting the first and second surfaces; A doped region located on a first surface of the silicon substrate; A doped conductive layer is located on a second surface of the silicon substrate, and the doped conductive layer includes a second side surface, the roughness of the second side surface being greater than the roughness of the first side surface, and the second side surface and the first side surface being located on the same side. A first passivation layer is located on one side of the first side surface. The first passivation layer includes a first part and a second part. The first part is located on the first side surface, and the second part is located on the second side surface. The second part includes a plurality of grooves. A conductive adhesive layer is located on the side of the second part away from the silicon substrate and fills the groove, and the conductive adhesive layer is electrically connected to the doped conductive layer.

2. The solar cell according to claim 1, characterized in that, The doped conductive layer includes a first doped conductive layer and a second doped conductive layer arranged sequentially along a first direction, the first direction being the direction intersecting the direction of the second doped conductive layer pointing towards the silicon substrate, the first doped conductive layer being in contact with the second doped conductive layer, and the second side being the surface of the second doped conductive layer away from the first doped conductive layer.

3. The solar cell according to claim 2, characterized in that, The doping concentration of the first doped conductive layer is less than that of the second doped conductive layer.

4. The solar cell according to claim 2, characterized in that, The doping concentration of the first doped conductive layer is 2e 20 / cm⁻³~3e 20 / cm⁻³, the doping concentration of the second doped conductive layer is 6e 20 / cm⁻³~8e 20 / cm⁻³.

5. The solar cell according to claim 2, characterized in that, The length of the second doped conductive layer in the first direction is 300nm~700nm, and the first direction is the direction that intersects with the direction in which the second doped conductive layer points to the silicon substrate.

6. A method for preparing a solar cell, characterized in that, The preparation method is used to prepare the solar cell according to any one of claims 1 to 5, and the preparation method includes: An initial solar cell is provided, the initial solar cell comprising an initial substrate and an initial doped conductive layer, the initial substrate having opposing first and second surfaces, the initial doped conductive layer being located on the second surface of the initial substrate; The initial solar cell is cut from the initial doped conductive layer along a cutting direction using a first cutting parameter, wherein the cutting direction is from the second surface of the initial substrate to the first surface of the initial substrate; When cutting to the initial substrate, the initial cell is cut along the cutting direction using the second cutting parameters to obtain a pre-treated cell including a doped conductive layer, a silicon substrate, and a doped region. The silicon substrate has a first side surface connecting the first surface and the second surface. The doped conductive layer includes a second side surface, the roughness of which is greater than that of the first side surface. The second side surface and the first side surface are located on the same side.

7. The method for preparing a solar cell according to claim 6, characterized in that, The first cutting parameter includes a first energy density of the laser, and the second cutting parameter includes a second energy density of the laser, wherein the first energy density is less than the second energy density.

8. The method for preparing a solar cell according to claim 7, characterized in that, The first energy density is 0.1 J / cm³. 2 ~0.13J / cm 2 The second energy density is 0.5 J / cm³. 2 ~2.0J / cm 2 .

9. The method for preparing a solar cell according to claim 6, characterized in that, The initial battery cell is further cut along the cutting direction using the second cutting parameters to obtain a pre-treated battery, including: During the process of continuing to cut the initial battery cell along the cutting direction using the second cutting parameters, a first doping gas is used to purge the first side so that the first side reacts with the first doping gas to obtain the pre-treated battery.

10. The method for preparing a solar cell according to claim 6, characterized in that, After obtaining the pretreated battery, the preparation method further includes: A first passivation layer is deposited on the first side and the second side, the first passivation layer comprising a first part and a second part, the first part being located on the first side and the second part being located on the second side; The second part is patterned to form multiple grooves in the second part; Conductive adhesive is injected into the groove to obtain a solar cell.

11. The method for preparing a solar cell according to claim 6, characterized in that, The doped conductive layer includes a first doped conductive layer and a second doped conductive layer. The first doped conductive layer is located on the side away from the second side, and the second doped conductive layer is located on the side closer to the second side. The concentration of the doping gas in the second doped conductive layer is 1.2 to 1.3 times the concentration of the doping gas in the first doped conductive layer.

12. The method for preparing a solar cell according to any one of claims 6 to 11, characterized in that, The depth of the cutting process is less than or equal to the length of the initial battery cell in the cutting direction.

13. A stacked battery, characterized in that, include: The base cell is a solar cell as described in any one of claims 1 to 5; The top battery is located on the bottom battery.

14. A photovoltaic module, characterized in that, include: A battery string is formed by connecting multiple solar cells, wherein the solar cells include the solar cells according to any one of claims 1 to 5, or are formed by connecting solar cells prepared by the method of preparing multiple solar cells according to any one of claims 6 to 12, or are formed by connecting multiple stacked cells according to claim 13. An encapsulating film is used to cover the surface of the battery string; A cover plate is used to cover the surface of the encapsulating film that faces away from the battery string.

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