Solar cell and method of manufacturing the same, photovoltaic module

Abstract

The application relates to a solar cell and a preparation method thereof and a photovoltaic module. The solar cell comprises a cell body, a passivation layer, a dielectric layer, a metal reflection layer and an electrode. The cell body has a first surface. The passivation layer is arranged on the first surface. The dielectric layer is arranged on a side surface of the passivation layer away from the cell body, and the material of the dielectric layer comprises fluorine. The metal reflection layer is arranged on a side surface of the dielectric layer away from the passivation layer. The electrode is arranged on the first surface side and is electrically connected with the cell body. By arranging the dielectric layer and the metal reflection layer on the passivation layer, the material of the dielectric layer comprises fluorine, the refractive index of the dielectric layer is greater than the refractive index of the metal reflection layer, when the incident angle of the photons is greater than the critical angle theta c, the photons are totally internally reflected to return to the inside of the cell body, meanwhile, part of the photons which do not satisfy the incident angle condition can be reflected by the metal reflection layer with high reflectivity to return to the inside of the cell body, the recycling rate of the photons is improved, and the photoelectric conversion efficiency of the cell is improved.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to solar cells and their preparation methods, and photovoltaic modules. Background Technology

[0002] With the development of photovoltaic technology, back-contact solar cells have advantages in reducing shading loss and improving the absorption and utilization rate of incident light due to their structure without grid lines blocking the front side, and thus have been widely used. Summary of the Invention

[0003] Therefore, it is necessary to provide a solar cell and its preparation method, as well as a photovoltaic module, to address the problem that recombination photons are easily released in current solar cells, thereby affecting the light absorption and utilization rate.

[0004] According to one aspect of this application, a solar cell is provided, comprising: a cell body having a first surface; a passivation layer disposed on the first surface; a dielectric layer disposed on a side surface of the passivation layer opposite to the cell body, the dielectric layer being made of a fluoride; a metal reflective layer disposed on a side surface of the dielectric layer opposite to the passivation layer; and an electrode disposed on the first surface side and electrically connected to the cell body.

[0005] In one embodiment, the fluoride includes at least one of magnesium fluoride and calcium fluoride.

[0006] In one embodiment, the material of the metal reflective layer includes at least one of silver, aluminum, and a silver-nickel alloy.

[0007] In one embodiment, the thickness of the metal reflective layer is 5µm-15µm.

[0008] In one embodiment, the thickness of the dielectric layer is 75nm-150nm.

[0009] In one embodiment, the reflectivity of the metal reflective layer is 93%-95.8%.

[0010] In one embodiment, the width of the electrode is smaller than the width of the metal reflective layer.

[0011] In one embodiment, a first through-hole is provided on the metal reflective layer, and a second through-hole is provided on the dielectric layer opposite to and connected to the first through-hole; the electrode is electrically connected to the battery body through the first through-hole and the second through-hole.

[0012] In one embodiment, a plurality of doped regions are provided on the first side of the battery body, the doping types of two adjacent doped regions are different, and a spacer region is provided between two adjacent doped regions; the electrode and the doped regions are electrically connected, and a metal reflective layer is provided on at least one doped region.

[0013] According to another aspect of this application, a method for fabricating a solar cell is provided, comprising: providing a cell body; forming a passivation layer on a first surface of the cell body; forming a dielectric layer on a side surface of the passivation layer opposite to the cell body, the dielectric layer being made of a fluoride; forming a metal reflective layer on a side surface of the dielectric layer opposite to the passivation layer; and forming an electrode electrically connected to the cell body to form a solar cell.

[0014] In one embodiment, a first doped region and a second doped region are provided on a first side of the battery body, and a spacer region is provided between the first doped region and the second doped region; a metal reflective layer is formed on the side surface of the dielectric layer opposite to the passivation layer, including: depositing metal material particles on the side surface of the dielectric layer opposite to the passivation layer to form a metal reflective layer; placing a mask on the metal reflective layer on the first doped region and the second doped region; and removing the metal reflective layer provided in the spacer region.

[0015] In one embodiment, a first doped region and a second doped region are provided on a first side of the battery body, and a spacer region is provided between the first doped region and the second doped region; a metal reflective layer is formed on the side surface of the dielectric layer opposite to the passivation layer, including: disposing an isolation paste on the dielectric layer of the spacer region and curing the isolation paste to form an isolation layer; forming an initial metal reflective layer on the side surface of both the isolation layer and the dielectric layer opposite to the battery body by an electroplating process; and removing the isolation layer and the initial metal reflective layer disposed on the isolation layer to form a metal reflective layer.

[0016] According to another aspect of this application, a photovoltaic module is provided, comprising: a battery string, wherein the battery string is formed by electrically connecting a plurality of solar cells as described above, or the battery string is formed by electrically connecting a plurality of solar cells prepared by the above-described solar cell preparation method; an encapsulation layer covering the surface of the battery string; and a cover plate covering the surface of the encapsulation layer away from the battery string.

[0017] The aforementioned solar cell, its fabrication method, and photovoltaic module, by sequentially disposing a dielectric layer and a metal reflective layer on the passivation layer of the first side of the cell body, wherein the dielectric layer is made of fluoride and has a refractive index greater than that of the metal reflective layer, when the incident angle of a photon is greater than the critical angle θc, the photon undergoes total internal reflection at the interface between the dielectric layer and the metal reflective layer and returns to the cell body. At the same time, some photons that do not meet the incident angle condition pass through the dielectric layer and are incident on the metal reflective layer, and can be reflected back to the cell body by the highly reflective metal reflective layer, thereby improving the photon recovery and utilization rate and thus improving the photoelectric conversion efficiency of the cell. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a solar cell according to some embodiments of this application from one viewpoint.

[0019] Figure 2 This is a schematic diagram of a solar cell according to some embodiments of this application from a frontal view.

[0020] Figure 3 This is a schematic diagram of a solar cell according to some embodiments of the present application from a frontal view.

[0021] Figure 4 This is a partial cross-sectional view of a solar cell according to some embodiments of this application from a frontal perspective.

[0022] Figure 5 This is a schematic flowchart illustrating a method for fabricating a solar cell according to some embodiments of this application.

[0023] Figure 6 This is a schematic flowchart illustrating a method for fabricating a solar cell according to other embodiments of this application.

[0024] Figure 7 This is a schematic flowchart illustrating a method for fabricating a solar cell according to some embodiments of this application.

[0025] Figure 8 This is a schematic diagram of the structure of a photovoltaic module according to some embodiments of this application.

[0026] Explanation of reference numerals in the attached drawings: 10, Battery body; 11, First surface; 12, Second surface; 13, Doped region; 14, Spacer region; 20, Passivation layer; 30, Dielectric layer; 31, Second via; 40, Metal reflective layer; 41, First via; 50, Electrode; 51, First grid line; 52, Second grid line; 60, Passivation and antireflection layer; 100, Battery string; 200, Encapsulation layer; 300, Cover plate; F1, First direction; F2, Second direction; F3, Third direction; H1, First thickness; H2, Second thickness; H3, Third thickness; L1, First width; L2, Second width; L3, Third width. Detailed Implementation

[0027] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0028] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0029] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0030] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., 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, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0031] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0032] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0033] In the accompanying drawings, the thicknesses of layers, films, regions, substrates, etc., are exaggerated for clarity. Throughout the specification, the same reference numerals refer to the same elements. It should be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it may be directly on the other element or there may be intervening elements. Conversely, when an element is referred to as being "directly on" another element, there are no intervening elements.

[0034] In addition, embodiments of the application are described with reference to cross-sectional views, which are schematic diagrams of some embodiments of the application, thus allowing for the expectation of variations in the illustrated shape due to, for example, manufacturing techniques and / or tolerances. Therefore, embodiments of the application should not be limited to the specific shape of the area shown herein, but should include shape deviations due to, for example, manufacturing techniques.

[0035] Furthermore, the use of terms such as "same," "equal," or "consistent" regarding dimensions in the description of the embodiments of this application does not require absolute mathematical or geometric precision. Given the actual manufacturing, measurement, and material factors, those skilled in the art should understand that the aforementioned dimensional terms include deviations within permissible limits or unavoidable deviations. As long as such deviations do not affect the realization of the corresponding dimensions' function and technical effect in this application, they should be considered to fall within the meaning of "same dimensions" as described in the embodiments of this application.

[0036] In related technologies, the theoretical limit efficiency of traditional monocrystalline silicon solar cells is approximately 29.56%, while the outermost film of back contact (BC) cells after passivation is silicon nitride (SiN). X Its light reflectance in the visible light range of 400nm-800nm ​​is only about 6%. During the operation of a solar cell, as electron-hole pairs migrate to the emitter, some charge carriers recombine to generate photons. These photons escape from the cell surface, causing energy loss, which leads to a decrease in light absorption and utilization rate and limits photoelectric conversion efficiency.

[0037] Based on this, the embodiments of this application provide a dielectric layer 30 and a metal reflective layer 40 on the surface of the battery. By utilizing the refractive index difference between the two media, the dielectric layer 30 and the metal reflective layer 40, some photons undergo total internal reflection (TIR) ​​and return to the battery body 10. At the same time, photons that pass through the dielectric layer 30 and are incident on the metal reflective layer 40 can be reflected back into the battery by the highly reflective metal reflective layer 40 and reabsorbed, thereby improving the light absorption and utilization rate and the photoelectric conversion efficiency.

[0038] According to some embodiments of this application, in conjunction with Figure 1 As shown, Figure 1 This is a schematic diagram of the structure of a solar cell according to some embodiments of this application from one viewpoint. Embodiments of this application provide a solar cell including a cell body 10, a passivation layer 20, a dielectric layer 30, a metal reflective layer 40, and an electrode 50.

[0039] The solar cell provided in this application embodiment is a back contact (BC) solar cell. The cell body 10 serves as the basic structure of the solar cell. Exemplarily, the interior of the cell body 10 may be processed by at least one of the following preliminary processes: texturing, diffusion, passivation, and doped layer deposition.

[0040] For example, the first direction F1 is along the length direction of the battery body 10, the second direction F2 is along the width direction of the battery body 10, and the third direction F3 is along the thickness direction of the battery body 10. For example, the first direction F1, the second direction F2, and the third direction F3 are perpendicular to each other. Along the third direction F3, the battery body 10 has a first surface 11 and a second surface 12 disposed opposite to each other, the first surface 11 is the backlight surface (back side), and the second surface is the light-receiving surface (front side).

[0041] For example, a passivation antireflection layer 60 is provided on the second surface 12 of the battery body 10. The passivation antireflection layer 60 is used to passivate the surface of the second surface 12 of the battery body 10 and reduce the reflection of incident light by the second surface 12. The material of the passivation antireflection layer 60 may include silicon nitride (SiN). X It is at least one of aluminum oxide (Al2O3), silicon oxide (SiO2), silicon oxynitride (SiON), or titanium oxide (TiO2).

[0042] The battery body 10 has multiple doped regions 13 on its first surface 11, such as P-type or N-type doped regions. Adjacent doped regions 13 have different doping types and are alternately arranged on the first surface 11. For example, as shown... Figure 2 As shown, Figure 2This is a schematic diagram of a solar cell according to some embodiments of this application from a frontal view. A spacer region 14 is provided between two adjacent doped regions 13 to electrically separate the two doped regions 13. In other embodiments, such as... Figure 3 As shown, Figure 3 This is a schematic diagram of a solar cell according to some embodiments of this application from a frontal view. There may be no spacer region 14 between two adjacent doped regions 13; this is not a specific limitation.

[0043] The battery body 10 may include a substrate and multiple doped structures (doped regions 13) disposed on the substrate. It should be noted that the battery body 10 is a pre-fabricated composite product; the battery body 10 actually comprises a multi-layered functional structure combination, rather than a single conventional silicon wafer. The substrate in the battery body 10 may be, but is not limited to, a silicon substrate. Exemplarily, the substrate material may include N-type silicon, and the doping element of the N-type silicon wafer includes at least one of phosphorus and antimony; in other embodiments, the substrate material may include P-type silicon, and the doping element of the P-type silicon wafer includes at least one of boron and gallium.

[0044] A passivation layer 20 is disposed on the first surface 11 side of the battery body 10, covering the entire surface area of ​​the first surface 11. The passivation layer 20 is used to passivate the surface of the first surface 11 of the battery body 10, reducing the surface recombination rate. Exemplarily, the material of the passivation layer 20 may include silicon nitride (SiN). X It is at least one of silicon oxide (SiO2), aluminum oxide (Al2O3), silicon oxynitride (SiON), or silicon carbide (SiC).

[0045] In one embodiment, the material of the passivation layer 20 includes silicon nitride (SiN). X The passivation layer 20 can be formed by plasma-enhanced chemical vapor deposition (PECVD) to enhance the adhesion to the silicon substrate.

[0046] The passivation layer 20 is located between the first surface 11 of the battery body 10 and the dielectric layer 30, providing passivation protection for the battery body 10. The dielectric layer 30 is disposed on the side surface of the passivation layer 20 facing away from the battery body 10. The material of the dielectric layer 30 includes fluorides. As a dielectric material, the fluoride has a refractive index greater than 1 in the visible light band. The dielectric layer 30 is located between the metal reflective layer 40 and the passivation layer 20, serving to separate the metal reflective layer 40 from the passivation layer 20 and reduce the contact between the metal reflective layer 40 and the passivation layer 20.

[0047] A metal reflective layer 40 is disposed on the surface of the dielectric layer 30 facing away from the passivation layer 20. The metal material used in the metal reflective layer 40 has a refractive index of less than 1 in the visible light band. Therefore, the refractive index of the dielectric layer 30 formed of fluoride material is greater than the refractive index of the metal reflective layer 40 formed of metal material.

[0048] Total internal reflection (TIR) ​​is an optical phenomenon: when light enters a medium with a lower refractive index from a medium with a higher refractive index, if the angle of incidence is greater than the critical angle θc, the light will undergo total internal reflection and will not enter the medium with a lower refractive index.

[0049] In other words, when light rays, i.e. photons generated and emitted by partial carrier recombination, travel from the higher refractive index dielectric layer 30 to the lower refractive index metallic reflective layer 40, and the incident angle of this portion of light rays is greater than the critical angle θ, C The light will undergo total internal reflection and will not enter the low-refractive-index metal reflective layer 40. At the same time, since the metal material used in the metal reflective layer 40 has high reflectivity, it can reflect light that does not meet the incident angle condition and is incident on the metal reflective layer 40 back into the battery body 10, thereby improving the photon recovery and utilization rate.

[0050] For example, taking magnesium fluoride (refractive index n1≈1.38) as the dielectric layer 30 and pure silver (refractive index n2≈0.05) as the metal reflective layer 40, the critical angle θc satisfies sin(θc)=n2 / n1=0.05 / 1.38≈0.036, i.e. θc≈2°. When the incident angle is greater than approximately 2°, the light can undergo total internal reflection at the interface and return to the interior of the battery body 10. Due to the small critical angle, most incident photons can satisfy the incident angle condition. For photons whose incident angle is less than the critical angle and do not meet the condition, they pass through the dielectric layer 30 and are incident on the surface of the metal reflective layer 40, but can be reflected back to the interior of the battery body 10 by the high reflectivity of the metal reflective layer 40 (e.g., up to 95.8% when using pure silver).

[0051] Electrode 50 is disposed on the first surface 11 and electrically connected to the battery body 10. Electrode 50 is used to collect charge carriers and conduct current.

[0052] It should be noted that electrical connection refers to two components being in contact or connected through a conductive material, enabling the battery body 10 to generate or supply electricity, and allowing charge to be transferred between the two components. It should be understood that in the non-operating state, there is not necessarily a potential difference or current between the two components; the ability to form a conductive path during operation is considered an electrical connection.

[0053] In one embodiment, the electrode 50 includes multiple gate lines, including a first gate line 51 and a second gate line 52. Exemplarily, the first gate line 51 includes a positive gate line, and the second gate line 52 includes a negative gate line. In another embodiment, the first gate line 51 includes a negative gate line, and the second gate line 52 includes a positive gate line. The first gate line 51 and the second gate line 52 are respectively used to collect charge carriers generated in regions with different doping types and to transport and exhaust the charge carriers along the extension direction of the gate lines.

[0054] Through the above-mentioned layered structure, the dielectric layer 30 and the metal reflective layer 40 in this application can cooperate to form a photon recovery mechanism. By utilizing the refractive index difference between the dielectric layer 30 with a higher refractive index and the metal reflective layer 40 with a lower refractive index, photons that meet the incident angle greater than the critical angle θc undergo total internal reflection and return to the battery body 10. At the same time, by utilizing the high reflectivity of the metal reflective layer 40, some photons that do not meet the incident angle condition and are incident on the surface of the metal reflective layer 40 are reflected back to the battery body 10, thereby achieving efficient recovery and utilization of photons and improving the conversion efficiency of the battery.

[0055] In some embodiments, the material of the dielectric layer 30 includes at least one of magnesium fluoride or calcium fluoride.

[0056] Magnesium fluoride refers to a fluoride material containing both magnesium and fluorine elements; calcium fluoride refers to a fluoride material containing both calcium and fluorine elements. In this embodiment, magnesium fluoride includes MgF2; calcium fluoride includes CaF2.

[0057] It should be noted that as long as the material contains both the corresponding metal element and fluorine, it can be considered as magnesium fluoride or calcium fluoride. This application does not limit the atomic ratio of each element. For example, the atomic ratio of magnesium to fluorine, or calcium to fluorine, can be, but is not limited to, a stoichiometric ratio of 1:2.

[0058] In one embodiment, the dielectric layer 30 is made of magnesium fluoride. Magnesium fluoride has a refractive index of approximately 1.38, which is higher than the refractive index of the metal reflective layer 40 (the refractive index of metals in the visible light band is less than 1). When photons with an incident angle greater than the critical angle θc are incident from the dielectric layer 30 (made of magnesium fluoride) to the metal reflective layer 40, total internal reflection occurs at the interface, returning the photons to the interior of the battery body 10. Photons that do not meet the incident angle condition pass through the interface and are reflected back by the highly reflective metal reflective layer 40.

[0059] In another embodiment, the dielectric layer 30 is made of calcium fluoride. Calcium fluoride has a refractive index of approximately 1.43; therefore, the refractive index of the dielectric layer 30 is higher than that of the metal reflective layer 40. When photons with an incident angle greater than the critical angle θc are incident from the dielectric layer 30 (made of calcium fluoride) towards the metal reflective layer 40, total internal reflection occurs at the interface, returning the photons to the interior of the battery body 10. Photons that do not meet the incident angle condition pass through the interface and are recovered by the highly reflective metal reflective layer 40.

[0060] In some embodiments, the material of the metal reflective layer 40 includes silver (Ag), aluminum (Al), or a silver-nickel alloy (AgNi). X At least one of the following.

[0061] In one embodiment, the metal reflective layer 40 is made of silver. When pure silver is used to form the metal reflective layer 40, the reflectivity of pure silver in the visible light range can reach more than 95.8%, which has high reflectivity and helps to reflect photons back into the battery body 10.

[0062] In another embodiment, the metal reflective layer 40 is made of aluminum. Aluminum has a slightly lower reflectivity in the visible light range than pure silver, but it is less expensive. Furthermore, aluminum has a lower density, resulting in a lighter weight for the same thickness, which helps reduce the overall weight of the battery. The aluminum reflective layer can be formed by vacuum evaporation or magnetron sputtering, allowing the deposition of both the dielectric layer 30 and the metal reflective layer 40 to be completed in the same vacuum system.

[0063] In another embodiment, the material of the metal reflective layer 40 includes a silver-nickel alloy. The silver-nickel alloy is formed by electroplating, in which silver ions and nickel ions in the electrolyte are co-deposited on the surface of the doped region 13 in a predetermined ratio to form the silver-nickel alloy reflective layer. The addition of nickel increases the hardness and wear resistance of the alloy, making the metal reflective layer 40 less prone to scratches or wear in subsequent processes. Simultaneously, nickel has a lower cost, reducing the amount of pure silver used and thus lowering material costs.

[0064] In other embodiments, the metal reflective layer 40 may include a multilayer structure, comprising a first reflective layer near the dielectric layer 30 and a second reflective layer away from the dielectric layer 30. Exemplarily, the first reflective layer is made of pure silver; the second reflective layer is made of a silver-nickel alloy, and the reflectivity of the first reflective layer is higher than that of the second reflective layer. This multilayer composite structure improves the mechanical properties of the metal reflective layer 40 while maintaining high reflectivity, reducing wear and scratches in subsequent processes.

[0065] In some embodiments, such as Figure 2 As shown, Figure 2 This is a schematic diagram of a solar cell according to some embodiments of this application from a frontal view. The thickness of the metal reflective layer 40 is 5µm-15µm.

[0066] In this embodiment, the thickness refers to the dimension of the corresponding film layer in the direction away from its adjacent layer (or the surface it covers), that is, the dimension in the direction perpendicular to the interface between the corresponding film layer and the adjacent layer.

[0067] For example, a passivation layer 20 is disposed on the first surface 11 of the battery body 10, and the dimension of the passivation layer 20 in the direction away from the battery body 10 is denoted as the third thickness H3; a dielectric layer 30 is disposed on the surface of the passivation layer 20 facing away from the battery body 10, and the dimension of the dielectric layer 30 in the direction away from the passivation layer 20 is denoted as the first thickness H1; a metal reflective layer 40 is disposed on the surface of the dielectric layer 30 facing away from the passivation layer 20, and the dimension of the metal reflective layer 40 in the direction away from the dielectric layer 30 is denoted as the second thickness H2.

[0068] It should be noted that when the surface covered by the corresponding film layer is a flat surface, the direction away from the adjacent layer is parallel to the third direction F3, and the thickness refers to the size of the film layer along the third direction F3; when the surface covered by the corresponding film layer is a non-flat surface (such as a pyramid-shaped textured surface formed by texturing), the thickness can refer to the average thickness or maximum thickness of the film layer along the direction away from the adjacent layer, and this application does not impose specific limitations on this.

[0069] For example, the thickness of the metal reflective layer 40, dielectric layer 30 and passivation layer 20 can be obtained by measuring the step height between the film layer and the substrate with a protractor, or by observing the cross-section of the film layer with a scanning electron microscope (SEM), or by measuring the optical thickness of the film layer with an ellipsometry and converting it. This application does not impose specific limitations on the method of thickness measurement.

[0070] When the thickness of the metal reflective layer 40 is 5µm-15µm, the metal reflective layer 40 can have good continuity and mechanical strength, is not easily damaged in subsequent processes, and can achieve a reflectivity of over 93%.

[0071] For example, the thickness of the metal reflective layer 40 can be selected from any one of 5µm, 6µm, 7µm, 8µm, 9µm, 10µm, 11µm, 12µm, 13µm, 14µm, or 15µm. Furthermore, the thickness of the metal reflective layer 40 can also be selected from different ranges, such as 5µm-10µm, 10µm-15µm, 5µm-12µm, or 8µm-15µm, to adapt to different process conditions and cost requirements.

[0072] In one embodiment, the thickness of the metal reflective layer 40 is 5µm, at which point the silver consumption of the metal reflective layer 40 is low and the reflectivity can still reach more than 93%.

[0073] In another embodiment, the thickness of the metal reflective layer 40 is 10µm. In this case, the silver mirror formed by pure silver material can achieve a reflectivity of 95.8% in the spectrum, and the reflectivity curve is almost flat in the visible light wavelength range of 400nm-800nm, which has good wide-band high reflectivity characteristics.

[0074] In another embodiment, the thickness of the metal reflective layer 40 is 15µm, in which case the metal reflective layer 40 has a relatively thick physical thickness and good mechanical strength.

[0075] In some embodiments, such as Figure 2 As shown, Figure 2 This is a schematic diagram of a solar cell according to some embodiments of this application from a frontal view. The thickness of the dielectric layer 30 is 75nm-150nm.

[0076] When the thickness of the dielectric layer 30 is 75nm-150nm, the dielectric layer 30 can have a good optical coupling effect, and the incident light can be well guided to the metal reflective layer 40 for reflection. At the same time, the propagation path of the light in the dielectric layer 30 is moderate, which is conducive to maintaining the total internal reflection effect.

[0077] For example, the thickness of the dielectric layer 30 can be selected from any one of 75nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, or 150nm. Furthermore, the thickness of the dielectric layer 30 can also be selected from different ranges, such as 75nm-100nm, 100nm-150nm, 75nm-120nm, or 100nm-150nm, to adapt to the optical coupling requirements of different wavelength bands.

[0078] In one embodiment, the dielectric layer 30 has a thickness of 75 nm, which is suitable for incident light with a shorter wavelength and has a better optical coupling effect. At the same time, the thickness of the dielectric layer 30 is not too thin and would affect the uniformity of the film.

[0079] In another embodiment, the dielectric layer 30 has a thickness of 100 nm, which can be used as a general thickness to take into account the optical performance of various wavelengths. This allows the incident light to obtain a suitable propagation path length within the dielectric layer 30, which is beneficial for forming stable total internal reflection conditions at the interface between the dielectric layer 30 and the metal reflective layer 40.

[0080] In another embodiment, the dielectric layer 30 has a thickness of 120 nm, which is suitable for incident light with wavelengths between the mid-wavelength and long-wavelength range of visible light.

[0081] In another embodiment, the dielectric layer 30 has a thickness of 150 nm, which is suitable for incident light with a longer wavelength, while the thickness of the dielectric layer 30 is not too thick to increase film stress or affect film adhesion strength.

[0082] In other embodiments, when the thickness of the dielectric layer 30 increases, the propagation path of the incident light within the dielectric layer 30 is lengthened, the total internal reflection effect is enhanced, and the number of photons reaching the surface of the metal reflective layer 40 decreases. In this case, the thickness of the metal reflective layer 40 can be reduced accordingly. For example, when the thickness of the dielectric layer 30 is within a relatively thick range, such as 120nm-150nm, the thickness of the metal reflective layer 40 can be adapted to a thinner range, such as 5µm-8µm, which can reduce the amount of material used while maintaining photon recovery efficiency.

[0083] In some embodiments, the reflectivity of the metal reflective layer 40 is between 93% and 95.8%.

[0084] When the reflectivity of the metal reflective layer 40 is between 93% and 95.8%, a relatively high proportion of photons can be reflected back into the battery body 10, which is beneficial to improving the photon recovery efficiency. The reflectivity is controlled within 95.8%, which is the upper limit that can be stably achieved under conventional process conditions when using pure silver materials.

[0085] For example, the reflectivity of the metal reflective layer 40 can be selected as 93%, 94%, 95%, 95.5%, or 95.8%. In addition, the reflectivity of the metal reflective layer 40 can also be selected from different ranges, such as 93%-95%, 94%-95.8%, or 93%-95.5%.

[0086] It should be noted that the reflectivity of the metal reflective layer 40 in this application can be measured by a spectrophotometer (such as an ultraviolet-visible spectrophotometer). During the measurement, an integrating sphere accessory can be used to measure the reflectivity of the metal reflective layer 40 to perpendicularly incident light or incident light at a specified angle in the wavelength range of 400nm-800nm, and the average value is taken as the reflectivity of the metal reflective layer 40. This application does not impose specific restrictions on the method of measuring reflectivity.

[0087] In some embodiments, such as Figure 4 As shown, Figure 4 This is a partial cross-sectional view of a solar cell according to some embodiments of this application from a frontal perspective. The width of the electrode 50 is smaller than the width of the metal reflective layer 40.

[0088] It should be noted that the width of the electrode 50 or the width of the metal reflective layer 40 mentioned in this embodiment refers to the dimension along the direction perpendicular to its extension direction when viewed from above or below the battery body 10. For example, the metal reflective layer 40 and the electrode 50 extend along the second direction F2, the width of the metal reflective layer 40 is a first width L1 along the first direction F1, and the width of the electrode 50 is a second width L2 along the first direction F1. Conversely, the metal reflective layer 40 and the electrode 50 extend along the first direction F1, the width of the metal reflective layer 40 is a first width L1 along the second direction F2, and the width of the electrode 50 is a second width L2 along the second direction F2.

[0089] By setting the width of electrode 50 to be smaller than the width of metal reflective layer 40, the edge area of ​​metal reflective layer 40 is not covered by electrode 50. The uncovered area of ​​metal reflective layer 40 can still reflect photons back into battery body 10, thereby increasing the reflection area and improving photon recovery efficiency.

[0090] The difference between the width of electrode 50 and the width of metal reflective layer 40 can be set according to actual needs. For example, the width of metal reflective layer 40 can be any value between 80µm and 200µm, and the width of electrode 50 can be any value between 50µm and 150µm.

[0091] In one embodiment, the width of electrode 50 is approximately equal to the width of metal reflective layer 40. The coverage area of ​​electrode 50 on metal reflective layer 40 substantially coincides with the width direction of metal reflective layer 40, and electrode 50 extends from one edge of metal reflective layer 40 to the other edge. This design reduces the alignment accuracy requirements between electrode 50 and metal reflective layer 40 during screen printing or silver paste printing. Even if a slight positional misalignment occurs during printing, electrode 50 can still cover metal reflective layer 40, allowing charge carriers collected from various locations on metal reflective layer 40 to be transported to electrode 50.

[0092] In some embodiments, such as Figure 4 As shown, Figure 4 This is a partial cross-sectional view of a solar cell according to some embodiments of this application from a frontal perspective. A first through-hole 41 is provided on the metal reflective layer 40, and a second through-hole 31 is provided on the dielectric layer 30, opposite to and communicating with the first through-hole 41. The electrode 50 is electrically connected to the battery body 10 through the first through-hole 41 and the second through-hole 31.

[0093] A first through-hole 41 is disposed on the metal reflective layer 40, and a second through-hole 31 is disposed on the dielectric layer 30. The two through-holes are opposite to each other along the thickness direction and are connected, forming a connecting channel that penetrates the metal reflective layer 40 and the dielectric layer 30 and extends to the surface of the battery body 10. The first through-hole 41 and the second through-hole 31 are formed by laser drilling. For example, a laser beam is focused on the surface of the metal reflective layer 40 and scanned point by point, first penetrating the metal reflective layer 40 to form the first through-hole 41, and then continuing to penetrate the dielectric layer 30 to form the second through-hole 31.

[0094] The first through hole 41 and the second through hole 31 are formed by laser drilling. The heat-affected area of ​​the laser beam on the metal reflective layer 40 and the dielectric layer 30 is small, which can reduce damage to adjacent film layers and battery body 10. At the same time, the aperture and depth of the laser drilling are controllable, which can form a through hole structure with neat edges, which is conducive to ensuring the uniformity of the electrode 50 slurry filling and improving the reliability of electrical connection.

[0095] In one embodiment, the first through hole 41 and the second through hole 31 are arranged at a predetermined interval along the extension direction of the grid line. For example, the spacing between adjacent groups of through holes can be any value between 0.5 mm and 2 mm.

[0096] In some embodiments, such as Figure 4 As shown, Figure 4 This is a partial cross-sectional view of a solar cell according to some embodiments of this application from a frontal perspective. The cross-sectional shape of the first through-hole 41 includes a circle or a square; and / or the cross-sectional shape of the second through-hole 31 includes a circle or a square.

[0097] In one embodiment, both the first through hole 41 and the second through hole 31 have circular cross-sectional shapes. When circular holes are formed by laser processing, the laser beam has a uniform energy distribution along a circular trajectory, resulting in smooth hole edges and reducing the likelihood of microcracks or burrs. The stress distribution in all directions is symmetrical within the circular holes, minimizing stress concentration around them during subsequent battery processing.

[0098] In another embodiment, both the first through-hole 41 and the second through-hole 31 have a square cross-sectional shape. Square holes have a larger internal surface area under the same aperture conditions, which increases the contact area between the electrode 50 slurry and the battery body 10, thus helping to reduce contact resistance. The straight edge segments of the square holes are parallel to the extension direction of the grid lines, which helps to form a uniform current collection path in the grid line arrangement direction.

[0099] In some embodiments, such as Figure 4 As shown, Figure 4 This is a partial cross-sectional view of a solar cell according to some embodiments of this application from a frontal perspective. The diameter of the first through-hole 41 is smaller than the width of the electrode 50; and / or the diameter of the second through-hole 31 is smaller than the width of the electrode 50.

[0100] It should be noted that the aperture dimensions of the first through-hole 41 and the second through-hole 31 refer to the cross-sectional dimensions perpendicular to their arrangement direction. For example, when the metal reflective layer 40 and the electrode 50 extend along the second direction F2, the aperture of the first through-hole 41 and the second through-hole 31 is a third width L3 along the first direction F1. Conversely, when the metal reflective layer 40 and the electrode 50 extend along the first direction F1, the aperture of the first through-hole 41 and the second through-hole 31 is a third width L3 along the second direction F2.

[0101] In one embodiment, the diameters of both the first through-hole 41 and the second through-hole 31 are smaller than the width of the electrode 50. By setting the diameters of both the first through-hole 41 and the second through-hole 31 to be smaller than the width of the electrode 50, it is ensured that after the electrode 50 paste fills the through-holes, the width of the electrode 50 extending on the surface of the metal reflective layer 40 is still sufficient to maintain the function of collecting and transporting charge carriers. For example, the diameters of the first through-hole 41 and the second through-hole 31 can be any value between 20µm and 60µm.

[0102] In some embodiments, such as Figure 2 As shown, Figure 2 This is a schematic diagram of a solar cell according to some embodiments of this application from a frontal view. A plurality of doped regions 13 are provided on the first surface 11 of the cell body 10. Adjacent doped regions 13 have different doping types, and a spacer region 14 is provided between adjacent doped regions 13. An electrode 50 is electrically connected to each doped region 13, and a metal reflective layer 40 is disposed on at least one doped region 13.

[0103] In one embodiment, a metal reflective layer 40 is disposed on one doped region 13. The metal reflective layer 40 only covers the region where the doped region 13 is located, and the electrode 50 corresponding to the doped region 13 collects the charge carriers in that region; the other doped region 13 is not provided with a metal reflective layer 40.

[0104] In another embodiment, a metal reflective layer 40 is disposed on multiple doped regions 13. The metal reflective layer 40 simultaneously covers the area where each doped region 13 is located, and the electrode 50 is disposed in the area where each doped region 13 is located. The metal reflective layer 40 only covers the area where the doped region 13 is located, and the spacer region 14 is not covered by the metal reflective layer 40, thereby reducing the risk of short circuit leakage between the P-electrode and the N-electrode through the metal reflective layer 40. By establishing an electrical connection between the doped regions 13 through the electrode structure, effective collection and external attraction of charge carriers are achieved.

[0105] In related technologies, the back-side stacked structure of the back contact battery needs to form a metal reflective layer 40 that covers only the doped region 13 and not the spacer region 14 to reduce the risk of leakage between the PN electrodes, and an electrode 50 electrically connected to the battery body 10 is formed on the metal reflective layer 40.

[0106] Based on this, such as Figure 5 As shown, Figure 5 This is a schematic flowchart illustrating a method for fabricating a solar cell according to some embodiments of this application.

[0107] This application provides a method for preparing a solar cell, which includes the following steps:

[0108] Step S1: Provide the battery body 10.

[0109] Step S2: A passivation layer 20 is formed on the first surface 11 of the battery body 10.

[0110] Step S3: A dielectric layer 30 is formed on the side of the passivation layer 20 facing away from the battery body 10. The material of the dielectric layer 30 includes fluorides.

[0111] Step S4: Form a metal reflective layer 40 on the side of the dielectric layer 30 facing away from the passivation layer 20.

[0112] Step S5: Form an electrode 50 electrically connected to the battery body 10 to form a solar cell.

[0113] In step S1, the battery body 10 has a first surface 11, which may be a backlight surface. The first surface 11 of the battery body 10 has multiple doped regions 13, with adjacent doped regions 13 having different doping types, and a spacer region 14 between adjacent doped regions 13. Exemplarily, the battery body 10 has completed preliminary processes, including at least one of the following steps: texturing, diffusion, passivation, or deposition of a doped layer.

[0114] In step S2, SiNx material is used to deposit a passivation layer 20 on the first surface 11 using plasma-enhanced chemical vapor deposition (PECVD). The thickness of the passivation layer 20 can be any value between 70nm and 90nm.

[0115] In step S3, the dielectric layer 30 is formed by physical vapor deposition.

[0116] In one embodiment, a dielectric layer 30 is formed on the surface of the passivation layer 20 using a fluoride material, such as magnesium fluoride or calcium fluoride, via physical vapor deposition (PVD). The PVD process can be performed using thermal evaporation or electron beam evaporation, controlling the thickness of the dielectric layer 30 to be between 75 nm and 150 nm. The fluoride material has a refractive index greater than 1 in the visible light band.

[0117] In step S4, the formation of the metal reflective layer 40 includes two stages: deposition of the metal material and patterning. For example, the material of the metal reflective layer 40 may include silver (Ag). Since the refractive index of the metal material in the visible light band is less than 1, the refractive index of the dielectric layer 30 formed using a fluoride material is greater than the refractive index of the metal reflective layer 40 formed using a metal material. When light rays, i.e., photons generated and emitted by partial carrier recombination, are incident from the higher refractive index dielectric layer 30 to the lower refractive index metal reflective layer 40, and the incident angle of this portion of the light ray is greater than the critical angle θc, the light ray will undergo total internal reflection and will not enter the lower refractive index metal reflective layer 40. Simultaneously, since the metal material used in the metal reflective layer 40 itself has high reflectivity, it can reflect light rays that do not meet the incident angle condition and are incident on the metal reflective layer 40 back into the battery body 10.

[0118] In step S5, electrodes 50 electrically connected to the battery body 10 are formed by laser drilling and silver paste printing.

[0119] By using the above-described method for preparing a solar cell, a passivation layer 20, a dielectric layer 30, and a metal reflective layer 40 are sequentially formed on the first surface 11 of the cell body 10. Through patterning, the metal reflective layer 40 is retained only in the area where the doped region 13 is located to reduce the risk of inter-electrode leakage. Electrodes 50 electrically connected to the cell body 10 are formed by laser drilling and silver paste printing, thereby preparing the above-described solar cell, improving the light absorption utilization rate, and thus improving the photoelectric conversion efficiency of the solar cell.

[0120] like Figure 6 As shown, Figure 6 This is a schematic flowchart illustrating a method for fabricating a solar cell according to other embodiments of this application.

[0121] In some embodiments, the first surface 11 of the battery body 10 is provided with a first doped region 13 and a second doped region 13 with different doping types, and a spacer region 14 is provided between the first doped region 13 and the second doped region 13.

[0122] In step S4, forming a metal reflective layer 40 on the surface of the dielectric layer 30 facing away from the passivation layer 20 includes:

[0123] Step S41: Metal material particles are deposited on the surface of the dielectric layer 30 on the side opposite to the passivation layer 20 to form a metal reflective layer 40. Exemplarily, silver particles are deposited on the surface of the dielectric layer 30 via a silver mirror reaction to form a uniform silver mirror across the entire surface. The silver ammonia solution used in the silver mirror reaction can be prepared from silver nitrate and ammonia.

[0124] Step S42: Deposit a mask onto the metal reflective layer 40 on the first doped region 13 and the second doped region 13. For example, the mask material includes an acid-resistant paste, and the mask can be printed onto the corresponding positions of the doped regions 13 of the metal reflective layer 40 using screen printing.

[0125] Step S43: Remove the metal reflective layer 40 disposed in the spacer region 14. Exemplarily, an oxidizing liquid is used to wash away the silver not covered by the mask on the spacer region 14. The oxidizing liquid can be dilute nitric acid or hydrogen peroxide. The mask is then removed, leaving the metal reflective layer 40 in the region containing the first doped region 13 and the second doped region 13.

[0126] like Figure 7 As shown, Figure 7 This is a schematic flowchart illustrating a method for fabricating a solar cell according to some embodiments of this application.

[0127] In some other embodiments, the first surface 11 of the battery body 10 is provided with a first doped region 13 and a second doped region 13 with different doping types, and a spacer region 14 is provided between the first doped region 13 and the second doped region 13.

[0128] In step S4, forming a metal reflective layer 40 on the surface of the dielectric layer 30 facing away from the passivation layer 20 includes:

[0129] Step S41: Apply the insulating paste to the dielectric layer 30 of the spacer region 14 and cure the insulating paste to form an insulating layer. For example, the insulating paste is an electroplating resistant insulating paste, which can be printed on the spacer region 14 by screen printing.

[0130] Step S42: An initial metal reflective layer 40 is formed on the surface of both the insulating layer and the dielectric layer 30 facing away from the battery body 10 by an electroplating process. Exemplarily, the electrolyte used in the electroplating process is a silver-ion-containing electroplating solution.

[0131] Step S43: Remove the isolation layer and the initial metal reflective layer 40 disposed on the isolation layer to form the metal reflective layer 40. Exemplarily, an oxidizing liquid is used to wash away the isolation layer and the initial metal reflective layer 40 disposed on the isolation layer. The metal reflective layer 40 is only retained in the regions where the first doped region 13 and the second doped region 13 are located, and the spacer region 14 is not covered by metal.

[0132] In some embodiments, before forming the electrode 50 electrically connected to the battery body 10 in step S5, the following steps are included:

[0133] Step S51: A hole is made in the metal reflective layer 40 and the dielectric layer 30 by laser process, so as to form a first through hole 41 in the metal reflective layer 40 and a second through hole 31 that is opposite to and connected to the first through hole 41 in the dielectric layer 30.

[0134] The process conditions for laser-driven aperture drilling are exemplarily as follows: using an ultraviolet laser or an infrared laser, the laser beam is focused on the surface of the metal reflective layer 40, and sequentially penetrates the metal reflective layer 40 at predetermined intervals (e.g., 0.5mm-2mm) along the extension direction of the gate lines to form a first through-hole 41 and a second through-hole 31 through the dielectric layer 30. Exemplarily, the apertures of the first through-hole 41 and the second through-hole 31 are controlled to be 20µm-60µm.

[0135] In some embodiments, forming an electrode 50 electrically connected to the battery body 10 includes: step S52, printing electrode 50 paste, wherein the electrode 50 paste is connected to the battery body 10 through a first through hole 41 and a second through hole 31.

[0136] The silver paste for the printed electrode 50 can be printed onto the surface of the metal reflective layer 40 using screen printing or jet printing. The silver paste fills the first through-hole 41 and the second through-hole 31 and contacts the battery body 10, with the width of the covered area being greater than the aperture of the first through-hole 41 and the second through-hole 31. For example, the silver paste material can be a conductive silver paste with a silver content of 70%-90% or a pure silver paste with a silver content of 100%.

[0137] Step S53: Curing electrode 50 slurry to form electrode 50.

[0138] After printing, a drying process is performed to melt and connect the silver particles in the silver paste and form a dense electrical contact with the battery body 10, thereby solidifying to form the electrode 50.

[0139] In related technologies, the output power and voltage of a single solar cell are limited, which cannot directly meet the needs of the load. In addition, the cell itself needs to be sealed and protected to reduce the impact of external moisture, oxygen and other corrosive elements.

[0140] Based on this, this application provides a photovoltaic module, which is formed by encapsulating multiple of the above-mentioned solar cells.

[0141] According to some embodiments of this application, such as Figure 8 As shown, Figure 8 This is a schematic diagram of the structure of a photovoltaic module according to some embodiments of this application.

[0142] The photovoltaic module provided in this application includes a battery string 100, an encapsulation layer 200, and a cover plate 300.

[0143] The battery string 100 is formed by electrically connecting multiple solar cells as described above via solder ribbons. The solder ribbons include tinned copper ribbons. Exemplarily, the solder ribbons are laid along the extension direction of the electrode 50 of the cell, and the width of the solder ribbons matches the width of the electrode 50. The solder ribbons are electrically connected to the electrode 50 of each solar cell via infrared welding or conductive bonding processes, connecting adjacent solar cells in series to form the battery string 100.

[0144] The solar cell can be any of the solar cells described in the foregoing embodiments, or it can be prepared using any of the preparation methods described in the foregoing embodiments.

[0145] An encapsulation layer 200 covers the surface of the battery string 100. Exemplarily, the encapsulation layer 200 may be disposed on both the light-receiving side and the backlight side of the battery string 100. The material of the encapsulation layer 200 includes ethylene-vinyl acetate copolymer (EVA) or polyolefin elastomer (POE), etc. The encapsulation layer 200 is bonded to the battery string 100 through a lamination process, serving a sealing, protective, and cushioning function.

[0146] The cover plate 300 covers the surface of the encapsulation layer 200 away from the battery string 100. The material of the cover plate 300 on the light-receiving side includes tempered glass; the material of the cover plate 300 on the back-light side includes glass or polyethylene terephthalate (PET) or polyvinyl fluoride (PVF).

[0147] The photovoltaic module may also include a frame, such as an aluminum alloy frame, for fixing and protecting the edges of the module; a junction box, located on the back of the photovoltaic module, with built-in bypass diodes to reduce the risk of hot spot effects; and busbars (such as tinned copper strips) for electrical connections between the cell strings 100 and between the cell strings 100 and the junction box.

[0148] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0149] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A solar cell, characterized in that, include: The battery body has a first side; A passivation layer is disposed on the first surface; A dielectric layer is disposed on the side surface of the passivation layer facing away from the battery body, and the material of the dielectric layer includes fluorides; A metal reflective layer is disposed on the surface of the dielectric layer that is opposite to the passivation layer; and An electrode is disposed on the first side and electrically connected to the battery body.

2. The solar cell according to claim 1, characterized in that, The fluoride includes at least one of magnesium fluoride and calcium fluoride.

3. The solar cell according to claim 1, characterized in that, The material of the metal reflective layer includes at least one of silver, aluminum, and silver-nickel alloy.

4. The solar cell according to any one of claims 1-3, characterized in that, The thickness of the metal reflective layer is 5µm-15µm.

5. The solar cell according to any one of claims 1-3, characterized in that, The thickness of the dielectric layer is 75nm-150nm.

6. The solar cell according to any one of claims 1-3, characterized in that, The reflectivity of the metal reflective layer is 93%-95.8%.

7. The solar cell according to any one of claims 1-3, characterized in that, The width of the electrode is smaller than the width of the metal reflective layer.

8. The solar cell according to any one of claims 1-3, characterized in that, The metal reflective layer is provided with a first through hole, and the dielectric layer is provided with a second through hole that is opposite to and communicates with the first through hole; The electrode is electrically connected to the battery body through the first through hole and the second through hole.

9. The solar cell according to any one of claims 1-3, characterized in that, The first side of the battery body is provided with multiple doped regions, the doping types of two adjacent doped regions are different, and there is a spacer region between two adjacent doped regions. The electrode and the doped region are electrically connected, and the metal reflective layer is disposed on at least one of the doped regions.

10. A method for preparing a solar cell, characterized in that, include: Provide battery body; A passivation layer is formed on the first surface of the battery body; A dielectric layer is formed on the side of the passivation layer facing away from the battery body, and the material of the dielectric layer includes fluorides; A metal reflective layer is formed on the surface of the dielectric layer that is opposite to the passivation layer; Electrodes are formed that are electrically connected to the battery body to form a solar cell.

11. The method for preparing a solar cell according to claim 10, characterized in that, The first surface of the battery body is provided with a first doped region and a second doped region, and a spacer region is provided between the first doped region and the second doped region. The formation of a metal reflective layer on the surface of the dielectric layer opposite to the passivation layer includes: The metal reflective layer is formed by depositing metal material microparticles on the surface of the dielectric layer on the side opposite to the passivation layer; A mask is placed on the metal reflective layer on the first doped region and the second doped region; Remove the metal reflective layer located in the interval area.

12. The method for preparing a solar cell according to claim 10, characterized in that, The first surface of the battery body is provided with a first doped region and a second doped region, and a spacer region is provided between the first doped region and the second doped region. The formation of a metal reflective layer on the surface of the dielectric layer opposite to the passivation layer includes: An insulating slurry is applied to the dielectric layer of the spacer region and then cured to form an insulating layer. An initial metallic reflective layer is formed on the surface of both the insulating layer and the dielectric layer that is opposite to the battery body by an electroplating process. The isolation layer and the initial metal reflective layer disposed on the isolation layer are removed to form the metal reflective layer.

13. A photovoltaic module, characterized in that, include: A battery string, wherein the battery string is formed by electrically connecting a plurality of solar cells as described in any one of claims 1-9, or the battery string is formed by electrically connecting a plurality of solar cells obtained by the method of preparing solar cells as described in any one of claims 10-12; An encapsulation layer covering the surface of the battery string; and A cover plate is applied to the surface of the encapsulation layer away from the battery string.

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