Solar cells and photovoltaic modules

Abstract

The present invention provides a solar cell and photovoltaic module. The solar cell comprises: an N-type substrate; an isolation structure located on a first surface; a doping structure; a first passivation layer; and a plurality of first electrodes. The doping structure comprises a first P-type doped emitter and a second P-type doped emitter, the second P-type doped emitter being located in a metal contact region; the isolation structure being located between two adjacent second P-type doped emitters, the isolation structure being used to isolate the first electrode from the N-type substrate; the first P-type doped emitter being located in a non-metallic contact region; the first passivation layer being located on a side of the doping structure in the non-metallic contact region away from the N-type substrate; and the first electrode being located on a side of the isolation structure away from the N-type substrate. Furthermore, the solar cell comprises a second tunneling dielectric layer, a second doped conductive layer, a second passivation layer, and a plurality of second electrodes located on a second surface. This solar cell solves the prior art technical problem of improving solar cell efficiency.

Description

Technical Field

[0001] The present application relates to the field of solar cells, and in particular to a solar cell and a photovoltaic module. Background Art

[0002] Solar cells have good photoelectric conversion capabilities. In solar cells, a diffusion process needs to be performed on the surface of the silicon wafer to prepare a PN junction.

[0003] In current solar cells, boron diffusion is typically performed on the surface of the silicon wafer to form an emitter. This emitter forms a PN junction with the silicon wafer and is electrically connected to a metal electrode, allowing carriers moving in the emitter to be collected by the metal electrode.

[0004] However, current solar cells have poor efficiency. Summary of the Invention

[0005] The main purpose of the present invention is to provide a solar cell and a photovoltaic module to solve the problem of how to improve the efficiency of solar cells in the prior art.

[0006] To achieve the above-mentioned object, according to one aspect of the present invention, a solar cell is provided, comprising: an N-type substrate, the N-type substrate comprising a first surface and a second surface opposite to each other, the first surface comprising a metal contact region and a non-metal contact region; an isolation structure, a doping structure, a first passivation layer, and a plurality of first electrodes located on the first surface, wherein the doping structure comprises a first P-type doped emitter and a second P-type doped emitter, the second P-type doped emitter being located in the metal contact region, the isolation structure being located between two adjacent second P-type doped emitters, the isolation structure being used to isolate the first electrode from the N-type substrate, the first P-type doped emitter being located in the non-metal contact region, the first passivation layer being located in the non-metal contact region on a side of the doping structure away from the N-type substrate, and the first electrode being located on a side of the isolation structure away from the N-type substrate; a second tunneling dielectric layer, a second doped conductive layer, a second passivation layer, and a plurality of second electrodes located on the second surface.

[0007] Furthermore, the isolation structure includes a stacked first doped conductive layer and a first tunneling dielectric layer, and the first doped conductive layer is located on a side of the first tunneling dielectric layer away from the N-type substrate.

[0008] Furthermore, the material of the first doped conductive layer is P-type amorphous silicon or P-type polysilicon, and the material of the first tunnel dielectric layer is silicon oxide.

[0009] Furthermore, the thickness of the first doped conductive layer is 1 to 2 nm, and the thickness of the first tunnel dielectric layer is 1 to 2 nm.

[0010] Furthermore, the doping concentration of the first doped conductive layer is less than or equal to the doping concentration of the second P-type doped emitter.

[0011] Furthermore, the doping concentration of the second P-type doped emitter is greater than the doping concentration of the first P-type doped emitter.

[0012] Furthermore, the second P-type doped emitter is also located in the non-metallic contact area.

[0013] Furthermore, the width of the portion of the second P-type doped emitter located in the metal contact area in the predetermined direction is a first width, and the width of the portion of the second P-type doped emitter located in the non-metal contact area in the predetermined direction is a second width, the ratio of the first width to the second width is 0.9 to 1.1, and the predetermined direction is perpendicular to the thickness direction of the N-type substrate.

[0014] Furthermore, the width of the portion of the second P-type doped emitter located in the metal contact area in the predetermined direction is a first width, the width of the isolation structure in the predetermined direction is a third width, the first width is smaller than the third width, and the predetermined direction is perpendicular to the thickness direction of the N-type substrate.

[0015] To achieve the above-mentioned object, according to one aspect of the present invention, there is provided a photovoltaic module, comprising: a cell string formed by connecting any one of the solar cells described above; an encapsulation layer for covering the surface of the cell string; and a cover plate for covering the surface of the encapsulation layer away from the cell string.

[0016] Applying the technical solution of the present invention, the above-mentioned solar cell includes an isolation structure located on the N-type substrate. On the one hand, the isolation structure can reduce the diffusion of metal ions from the first electrode to the N-type substrate, thereby reducing the content of metal ions diffused into the N-type substrate, reducing the generation of metal elements, and avoiding the destruction of the N-type substrate, thereby solving the problem in the related art that the diffusion of ions in the electrode forms metal elements, which will damage other structures of the battery and thus reduce the photoelectric conversion efficiency of the battery. On the other hand, because the material of the isolation structure has a certain optical absorption coefficient, when light is incident, part of the light will be absorbed by the isolation structure, thereby reducing the light absorption of the N-type substrate and causing optical absorption loss. In this solution, the orthographic projection of the isolation structure on the N-type substrate is located within the orthographic projection of the first electrode on the N-type substrate, which can make the isolation structure completely hidden under the first electrode, further reducing the optical absorption loss caused by the isolation structure, improving the optical absorption efficiency of the solar cell, and thus improving the efficiency of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0018] Figure 1 A schematic structural diagram of a solar cell provided according to an embodiment of the present application is shown;

[0019] Figure 2 A schematic structural diagram of another solar cell provided according to an embodiment of the present application is shown;

[0020] Figure 3 A schematic structural diagram of a photovoltaic assembly provided according to an embodiment of the present application is shown.

[0021] The above drawings include the following reference numerals:

[0022] 10. N-type substrate; 11. Metal contact area; 12. Non-metal contact area; 13. Isolation structure; 131. First doped conductive layer; 132. First tunneling dielectric layer; 14. Doping structure; 141. First P-type doped emitter; 142. Second P-type doped emitter; 15. First passivation layer; 16. First electrode; 17. Second tunneling dielectric layer; 18. Second doped conductive layer; 19. Second passivation layer; 20. Second electrode; W1. First width; W2. Second width; W3. Third width; 40. Solar cell; 402. Conductive tape; 41. Encapsulation layer; 42. Cover. DETAILED DESCRIPTION

[0023] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0024] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0025] It should be noted that the terms "first," "second," and the like in the specification and claims of the present invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate for the embodiments of the present invention described herein. In addition, the terms "including," "having," and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to these processes, methods, products, or apparatuses.

[0026] As introduced in the background art, the efficiency of solar cells in the prior art is not ideal. In order to solve the above technical problems, the present application proposes a solar cell and a photovoltaic module.

[0027] Figure 1 Schematic diagram of the structure of a solar cell according to an embodiment of the present application. Figure 1 and Figure 2 Shown, including:

[0028] An N-type substrate 10, wherein the N-type substrate 10 includes a first surface and a second surface opposite to each other, and includes a metal contact region 11 and a non-metal contact region 12;

[0029] an isolation structure 13, a doping structure 14, a first passivation layer 15, and a plurality of first electrodes 16 located on the first surface, wherein the doping structure 14 includes a first P-type doped emitter 141 and a second P-type doped emitter 142, the second P-type doped emitter 142 being located in the metal contact region 11, the isolation structure 13 being located between two adjacent second P-type doped emitters 142, the isolation structure 13 being used to isolate the first electrode 16 from the N-type substrate 10, the first P-type doped emitter 141 being located in the non-metallic contact region 12, the first passivation layer 15 being located on a side of the doping structure 14 in the non-metallic contact region 12 away from the N-type substrate 10, and the first electrode 16 being located on a side of the isolation structure 13 away from the N-type substrate 10;

[0030] A second tunneling dielectric layer 17 , a second doped conductive layer 18 , a second passivation layer 19 and a plurality of second electrodes 20 are located on the second surface.

[0031] Specifically, the first surface of the N-type substrate can be the front surface and the second surface can be the back surface, or the first surface of the N-type substrate can be the back surface and the second surface can be the front surface. That is, the solar cell is a single-sided cell, and the front surface can serve as the light-receiving surface for receiving incident light, while the back surface serves as the backlight surface. The N-type substrate is doped with an N-type doping element, which can be any Group V element such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The metal contact area extends in a predetermined direction. It should be noted that a first electrode will be formed on the first surface of the N-type substrate (the upper surface when a person is facing a screen or paper) in a subsequent step. The orthographic projection of the first electrode on the first surface of the N-type substrate is located within the metal contact area. In other words, the metal contact area is the portion of the first surface corresponding to the first electrode. In the predetermined direction, the width of the metal contact area can be equal to the width of the first electrode, or it can be greater than the width of the first electrode. The non-metallic contact area is the area on the first surface other than the metal contact area. In some specific embodiments, the width of the metal area on the first surface in the predetermined direction is 1.5 to 2 times the width of the first electrode in the predetermined direction. In this way, when manufacturing the first electrode, the formable area of ​​the electrode is relatively large, and the requirements for manufacturing processes such as alignment are more relaxed.

[0032] In some embodiments, the solar cell is a TOPCON (Tunnel Oxide Passivated Contact) cell, or the solar cell is a bifacial cell, that is, the first surface and the second surface of the N-type substrate can both serve as light-receiving surfaces and can be used to receive incident light.

[0033] In some embodiments, the first surface and the second surface are both non-flat surfaces. The non-flat surfaces can increase the internal reflection of the incident light, thereby further improving the utilization rate of light by the solar cell. More specifically, the cross section of the non-flat surface along the thickness direction of the N-type substrate is a line segment, and the line segment can include at least one of a straight line segment and a curved line segment, that is, the line segment can be composed of a straight line segment, or a curved line segment, or a curved line segment and a straight line segment. In the case where only straight line segments are composed, the line segment is composed of a plurality of straight line segments connected in sequence. In a specific embodiment, Figure 1 As shown, the cross section of the first surface along the thickness direction of the N-type substrate is zigzag-shaped, that is, it is composed of a plurality of straight line segments connected in sequence.

[0034] The isolation structure of the present application may be a single-layer structure or a multi-layer structure. Those skilled in the art may set an appropriate number of layers to form an isolation structure based on actual conditions. Furthermore, the material of the isolation structure of the present application may include one or more of silicon oxide, polycrystalline silicon, and amorphous silicon. Those skilled in the art may select an appropriate material to form an isolation structure based on actual conditions.

[0035] The above-mentioned doping structure can be obtained by diffusing and doping P-type ions on the surface portion of the N-type substrate, and the doped portion of the N-type substrate is converted into a doping structure. Specifically, in some embodiments, the P-type doping element can be any one of the Group III elements such as boron (B), aluminum (Al), gallium (Ga) or indium (In). In addition, the doping concentration of the above-mentioned first P-type doped emitter and the doping concentration of the second P-type doped emitter are different. That is, the doping concentration of the first P-type doped emitter is greater than the doping concentration of the second P-type doped emitter, or the doping concentration of the first P-type doped emitter is less than the doping concentration of the second P-type doped emitter. Those skilled in the art can set the appropriate doping concentration according to actual conditions to form the above-mentioned first P-type doped emitter and the second P-type doped emitter.

[0036] The first passivation layer may be a single-layer structure or a stacked-layer structure. The material of the first passivation layer may include one or more of silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride oxide, titanium oxide, hafnium oxide, or aluminum oxide. The specific material and number of layers are not limited in this application, and those skilled in the art can set them according to actual conditions.

[0037] The above-mentioned first passivation layer has a plurality of first passivation parts arranged at intervals, and a first opening is provided between two adjacent first passivation parts. The above-mentioned first electrode is located in the above-mentioned first opening, and the first electrode is in contact with the isolation structure and the second P-type doped emitter respectively. The material of the first electrode may include one or more of aluminum, silver, gold, nickel, molybdenum or copper.

[0038] Specifically, the second tunneling dielectric layer is located between the second surface of the N-type substrate and the second doped conductive layer. The second tunneling dielectric layer can constitute a passivation contact layer together with the second doped conductive layer. The second tunneling dielectric layer is used to passivate the second surface of the N-type substrate, play a chemical passivation effect, and reduce interface states. The material of the second tunneling dielectric layer can be a dielectric material, for example, including silicon oxide, magnesium fluoride, silicon oxide, amorphous silicon, polycrystalline silicon, silicon carbide, silicon nitride, silicon oxynitride, or aluminum oxide, titanium oxide. The specific material is not limited in this application, and those skilled in the art can set it according to actual conditions.

[0039] The above-mentioned second doped conductive layer can be a single-layer structure or a multi-layer structure. In addition, the material of the above-mentioned second doped conductive layer can include one or more of polycrystalline silicon and amorphous silicon. The second passivation layer is located on the side of the second doped conductive layer away from the second tunnel dielectric layer. The second passivation layer can be a single-layer structure or a stacked structure. The material of the second passivation layer can include one or more of silicon oxide, silicon nitride, silicon oxynitride, carbon nitride silicon oxide, titanium oxide, hafnium oxide or aluminum oxide. The specific materials and number of layers of the second doped conductive layer and the above-mentioned second passivation layer are not limited in this application, and those skilled in the art can set them according to actual conditions.

[0040] The second passivation layer includes a plurality of spaced-apart second passivation portions, with a second opening defined between adjacent second passivation portions. The second electrode is located in the second opening and in contact with the second doped conductive layer. The material of the second electrode may include one or more of aluminum, silver, gold, nickel, molybdenum, or copper. The present application does not limit the specific material of the second electrode, and those skilled in the art may select the material based on actual circumstances.

[0041] The solar cell of the present application includes an isolation structure located on an N-type substrate. On the one hand, the isolation structure can reduce the diffusion of metal ions of the first electrode to the N-type substrate, thereby reducing the content of metal ions diffused into the N-type substrate, reducing the generation of metal elements, and avoiding the destruction of the N-type substrate, thereby solving the problem in the related art that the ions in the electrode diffuse to form metal elements, which will destroy other structures of the battery and thus reduce the photoelectric conversion efficiency of the battery. On the other hand, since the material of the isolation structure has a certain optical absorption coefficient, when light is incident, part of the light will be absorbed by the isolation structure, thereby reducing the light absorption of the N-type substrate, resulting in optical absorption loss. In this solution, the positive projection of the isolation structure on the N-type substrate is located within the positive projection of the first electrode on the N-type substrate, which can make the isolation structure completely hidden under the first electrode, further reducing the optical absorption loss caused by the isolation structure, improving the optical absorption efficiency of the solar cell, and thus improving the efficiency of the solar cell.

[0042] In a specific embodiment of the present application, Figure 2As shown, the isolation structure 13 includes a stacked first doped conductive layer 131 and a first tunneling dielectric layer 132. The first doped conductive layer 131 is located on the side of the first tunneling dielectric layer 132 away from the N-type substrate 10. Compared to a single-layer isolation structure 13, the first doped conductive layer in this embodiment can form an energy band bend on the surface of the N-type substrate. The first tunneling dielectric layer can cause an asymmetric shift in the energy band on the surface of the N-type substrate, making the potential barrier for majority carriers lower than the potential barrier for minority carriers. Therefore, majority carriers can more easily undergo quantum tunneling through the first tunneling dielectric layer, while minority carriers have difficulty passing through the first tunneling dielectric layer, thereby achieving selective carrier transmission. Furthermore, the first tunneling dielectric layer can provide a chemical passivation effect. That is, due to the presence of interface state defects at the interface between the N-type substrate and the first tunneling dielectric layer, the interface state density on the back side of the N-type substrate is reduced. This reduction in interface state density inhibits the recombination of photogenerated carriers, increasing the fill factor, short-circuit current, and open-circuit voltage of the solar cell, thereby improving the solar cell's photoelectric conversion efficiency. Furthermore, the first doped conductive layer can provide a field passivation effect. Specifically, an electrostatic field is formed on the surface of the N-type substrate, directed toward the interior of the N-type substrate, causing minority carriers to escape from the interface, thereby reducing the minority carrier concentration and the carrier recombination rate at the N-type substrate interface. This increases the open-circuit voltage, short-circuit current, and fill factor of the solar cell, further improving the solar cell's photoelectric conversion efficiency.

[0043] Specifically, the doping type of the first doped conductive layer is opposite to that of the N-type substrate, while the doping type of the second doped conductive layer is the same as that of the N-type substrate. That is, the doping type of the first doped conductive layer is P-type, and the doping type of the second doped conductive layer is P-type. Furthermore, the thickness, density, and uniformity of the first tunneling dielectric layer affect the passivation quality. After high-temperature annealing, the impurities in the first doped conductive layer diffuse into the N-type substrate. The diffusion region formed beneath the first tunneling dielectric layer can regulate carrier transport and recombination behavior.

[0044] In some embodiments, the material of the first tunnel dielectric layer may include at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or magnesium fluoride. The material of the first doped conductive layer may include at least one of amorphous silicon, polycrystalline silicon, or silicon carbide.

[0045] In a specific implementation method of the present application, the material of the above-mentioned first doped conductive layer is P-type amorphous silicon or P-type polycrystalline silicon, and the material of the above-mentioned first tunneling dielectric layer is silicon oxide. The use of silicon oxide material in the first tunneling dielectric layer can further reduce the interface state density between the N-type substrate and the first doped dielectric layer, effectively reduce the recombination probability of electrons and holes, and thus provide high-quality chemical passivation to passivate the surface defects of the N-type substrate. The use of doped polycrystalline silicon or amorphous silicon material in the first doped conductive layer can better induce energy band bending, thereby providing field passivation. Combining the above-mentioned two passivation methods of chemical passivation and field passivation can further enhance the passivation effect of the isolation structure.

[0046] Specifically, amorphous silicon and polycrystalline silicon can be grown at low temperatures using techniques such as chemical vapor deposition, simplifying the manufacturing process and reducing manufacturing costs. Similarly, silicon oxide can reduce the interface state density between the silicon substrate and polycrystalline silicon through chemical passivation, effectively reducing the probability of electron-hole recombination, thereby increasing the open-circuit voltage of the battery.

[0047] In a specific implementation method of the present application, the thickness of the first doped conductive layer is 1 to 2 nm, and the thickness of the first tunnel dielectric layer is 1 to 2 nm. The thickness of the first doped conductive layer or the first tunnel dielectric layer should not be too thick. If the thickness of the first doped conductive layer is too thick, it may affect the overall thickness of the solar cell, thereby affecting the efficiency of the solar cell; if the thickness of the first tunnel dielectric layer is too thick, it may affect the quantum tunneling of majority carriers in the first tunnel dielectric layer, thereby affecting the selective transmission of carriers. The thickness of the first doped conductive layer or the first tunnel dielectric layer should not be too thin. If the thickness of the first doped conductive layer or the first tunnel dielectric layer is too thin, it may affect the isolation effect of the isolation structure. The thickness setting of the first doped conductive layer and the first tunnel dielectric layer can further simultaneously ensure the isolation effect of the isolation structure and the demand for thinness of the solar cell.

[0048] In practical applications, the thickness of the first doped conductive layer and the thickness of the first tunnel dielectric layer may be the same or different. The thickness of the first doped conductive layer may be 1 nm to 1.2 nm, 1.2 nm to 1.4 nm, 1.4 nm to 1.6 nm, 1.6 nm to 1.8 nm, or 1.8 nm to 2 nm. The thickness of the first tunnel dielectric layer may be 1 nm to 1.2 nm, 1.2 nm to 1.4 nm, 1.4 nm to 1.6 nm, 1.6 nm to 1.8 nm, or 1.8 nm to 2 nm.

[0049] In another embodiment of the present application, the doping concentration of the first doped conductive layer is less than or equal to the doping concentration of the second P-type doped emitter. The doping concentration of the first doped conductive layer should not be too high. If the doping concentration of the first doped conductive layer is too high, doped ions may enter the first tunneling oxide layer, damaging the structure of the first tunneling oxide layer, thereby affecting the passivation effect of the first tunneling oxide layer. Therefore, the doping concentration of the first doped conductive layer is less than or equal to the doping concentration of the second P-type doped emitter, which can further ensure a high transmission efficiency of the solar cell.

[0050] Specifically, the doping concentration of the first doped conductive layer is greater than the doping concentration in the N-type substrate, so as to form a sufficiently high potential barrier on the other side of the N-type substrate, so that majority carriers in the N-type substrate can pass through the first tunneling dielectric layer to the first doped conductive layer.

[0051] In some specific embodiments, the doping concentration of the second P-type doped emitter is greater than the doping concentration of the first P-type doped emitter. Such a doping concentration design can reduce the recombination of carriers on the surface caused by the higher doping concentration, thereby ensuring a longer minority carrier lifetime, and further ensuring a higher open circuit voltage and short circuit current of the battery, thereby making the photoelectric conversion efficiency of the solar cell higher; on the other hand, such a doping concentration design can reduce the problem of higher contact resistance caused by lower doping concentration, thereby ensuring a lower contact resistance and a lower turn-on voltage of the battery, and also improving the photoelectric conversion efficiency; on the other hand, the carriers can be transferred to the N-type substrate faster due to the concentration difference between the first emitter and the second emitter, which is also conducive to improving the photoelectric conversion efficiency. Therefore, such a concentration design makes the photoelectric conversion efficiency of the solar cell higher.

[0052] Specifically, the doping concentration of the first P-type doped emitter is 1E 14 ~9E 19 atom / cm 3 The doping concentration of the second P-type doped emitter is 1E 15 ~9E 20 atom / cm 3 .

[0053] To further ensure accurate overprinting of the first electrode and the second P-type doped emitter during fabrication of the first electrode, in a specific implementation of the present application, the second P-type doped emitter is further located in the non-metallic contact region. Placing the second P-type doped emitter in the non-metallic contact region allows for sufficient overprinting space for the first electrode, further ensuring accuracy during overprinting of the first electrode.

[0054] In a specific implementation method of the present application, Figure 1As shown, the portion of the second P-type doped emitter 142 located in the metal contact region 11 has a first width W1 in a predetermined direction, and the portion of the second P-type doped emitter 142 located in the non-metal contact region 12 has a second width W2 in the predetermined direction. The ratio of the first width W1 to the second width W2 is 0.9 to 1.1, and the predetermined direction is perpendicular to the thickness of the N-type substrate 10. The width of the second P-type doped emitter 142 in the metal contact region and the non-metal contact region is substantially the same, further ensuring both direct contact between the second P-type doped emitter 142 and the first electrode 16 and overprinting of the first electrode 16.

[0055] like Figure 1 As shown, the portion of the second P-type doped emitter 142 located in the metal contact region 11 has a first width W1 in a predetermined direction, and the isolation structure 13 has a third width W3 in the predetermined direction, wherein the first width W1 is less than the third width W3. The width of the isolation structure 13 is greater than the width of the second P-type doped emitter 142 located in the metal contact region 11, thereby increasing the area separating the first electrode 16 from the N-type substrate 10, reducing carrier recombination losses at the interface between the first electrode 16 and the doped structure 14, and further enhancing the passivation effect.

[0056] The above technical solution of the present application can be used for full back electrode contact cells with busbar-free technology (0BB) or multi-busbar technology (MBB, MULTI-BUSBAR), full back electrode contact cells (IBC, Interdigitated Back Contact), full back contact cell solar cells (ABC, All Back Contact), composite passivated back contact cells (HPBC, Hybrid Passivated Back Contact), emitter back passivated cells (PERC, Passivated Emitter and Rear Cell), tunneling oxide passivated contact cells (TOPcon, Tnuuel Oxide Passivated contact), TOPcon-IBC cells, crystalline silicon heterojunction solar cells (HJT, Heterojunction with Intrinsic Thin-layer), perovskite stacked cells, flexible cells and other photovoltaic cells to test the tunneling resistance or other arbitrary thin layer resistance.

[0057] In another typical embodiment of the present application, a photovoltaic cell is provided, such as Figure 3 As shown, the photovoltaic module includes:

[0058] A battery string is formed by connecting a plurality of solar cells 40 according to any one of the above embodiments;

[0059] Specifically, two adjacent cell strings can be electrically connected via a conductive ribbon 402. In some embodiments, the electrodes of the same polarity of the solar cells 40 are oriented in the same direction, and the conductive ribbon 402 connects the electrodes of the different polarities of two adjacent solar cells 40. In other embodiments, the solar cells 40 can also be arranged according to electrodes of different polarities, that is, the electrodes of multiple adjacent cells are arranged in the order of first polarity, second polarity, and first polarity, and the conductive ribbon 402 connects two adjacent cells on the same side. In some embodiments, there is no spacing between the cells, that is, the cells overlap.

[0060] An encapsulation layer 41 is used to cover the surface of the battery string;

[0061] Specifically, encapsulation layer 41 includes a first encapsulation layer and a second encapsulation layer. The first encapsulation layer covers either the front or back surface of the solar cell string, and the second encapsulation layer covers the other of the front or back surface of the solar cell string. Specifically, the material of encapsulation layer 41 can be at least one of organic encapsulation films such as polyvinyl butyral (PVB), ethylene-vinyl acetate copolymer (EVA), polyethylene octene co-elastomer (POE), or polyethylene terephthalate (PET). In actual applications, a gap exists between the first and second encapsulation layers before lamination, but after lamination, the first and second encapsulation layers together form the encapsulation layer 41.

[0062] The cover plate 42 is used to cover the surface of the packaging layer 41 away from the battery string.

[0063] Specifically, the cover plate 42 can be made of a light-transmitting material such as glass or plastic. Furthermore, the surface of the cover plate 42 facing the encapsulation layer 41 can be concave and convex to increase the utilization of incident light. The cover plate 42 includes a first cover plate and a second cover plate. The first cover plate is disposed opposite the first encapsulation layer, and the second cover plate is disposed opposite the second encapsulation layer.

[0064] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0065] 1. The solar cell of the present application includes an isolation structure located on an N-type substrate. On the one hand, the isolation structure can reduce the diffusion of metal ions from the first electrode to the N-type substrate, thereby reducing the content of metal ions diffused into the N-type substrate, reducing the generation of metal elements, and avoiding the destruction of the N-type substrate, thereby solving the problem in the related art that the diffusion of ions in the electrode forms metal elements, which will destroy other structures of the battery and thus reduce the photoelectric conversion efficiency of the battery. On the other hand, since the material of the isolation structure has a certain optical absorption coefficient, when light is incident, part of the light will be absorbed by the isolation structure, thereby reducing the light absorption of the N-type substrate, resulting in optical absorption loss. In this solution, the orthographic projection of the isolation structure on the N-type substrate is located within the orthographic projection of the first electrode on the N-type substrate, which can make the isolation structure completely hidden under the first electrode, further reducing the optical absorption loss caused by the isolation structure, improving the optical absorption efficiency of the solar cell, and thus improving the efficiency of the solar cell.

[0066] 2. The photovoltaic cell of the present application includes a cell string formed by connecting solar cells, and the solar cell includes an isolation structure located on an N-type substrate. On the one hand, the isolation structure can reduce the diffusion of metal ions of the first electrode to the N-type substrate, thereby reducing the content of metal ions diffused into the N-type substrate, reducing the production of metal elements, and avoiding the destruction of the N-type substrate, thereby solving the problem in the related art that the diffusion of ions in the electrode forms metal elements, which will destroy other structures of the battery and thus reduce the photoelectric conversion efficiency of the battery. On the other hand, because the material of the isolation structure has a certain optical absorption coefficient, when light is incident, part of the light will be absorbed by the isolation structure, thereby reducing the light absorption of the N-type substrate, resulting in optical absorption loss. In this solution, the positive projection of the isolation structure on the N-type substrate is located within the positive projection of the first electrode on the N-type substrate, which can make the isolation structure completely hidden under the first electrode, further reducing the optical absorption loss caused by the isolation structure, improving the optical absorption efficiency of the solar cell, and thus improving the efficiency of the solar cell.

Claims

1. A solar cell, characterized in that: include: An N-type substrate, the N-type substrate comprising a first surface and a second surface opposite to each other, the first surface comprising a metal contact region and a non-metal contact region; an isolation structure, a doping structure, a first passivation layer, and a plurality of first electrodes located on the first surface, wherein the doping structure includes a first P-type doped emitter and a second P-type doped emitter, the second P-type doped emitter is located in the metal contact region, the isolation structure is located between two adjacent second P-type doped emitters, the isolation structure is used to isolate the first electrode from the N-type substrate, the first P-type doped emitter is located in the non-metallic contact region, the first electrode is in contact with the second P-type doped emitter, the first passivation layer is located on a side of the doping structure in the non-metallic contact region away from the N-type substrate, the first electrode is located on a side of the isolation structure away from the N-type substrate, the orthographic projection of the isolation structure on the N-type substrate is a first projection, the orthographic projection of the first electrode on the N-type substrate is a second projection, and the first projection is located within the second projection; A second tunneling dielectric layer, a second doped conductive layer, a second passivation layer and a plurality of second electrodes are located on the second surface.

2. The solar cell according to claim 1, wherein The isolation structure includes a stacked first doped conductive layer and a first tunneling dielectric layer, wherein the first doped conductive layer is located on a side of the first tunneling dielectric layer away from the N-type substrate.

3. The solar cell according to claim 2, wherein The material of the first doped conductive layer is P-type amorphous silicon or P-type polysilicon, and the material of the first tunnel dielectric layer is silicon oxide.

4. The solar cell according to claim 2, wherein The thickness of the first doped conductive layer is 1-2 nm, and the thickness of the first tunnel dielectric layer is 1-2 nm.

5. The solar cell according to claim 2, wherein The doping concentration of the first doped conductive layer is less than or equal to the doping concentration of the second P-type doped emitter.

6. The solar cell according to claim 1, wherein The doping concentration of the second P-type doped emitter is greater than the doping concentration of the first P-type doped emitter.

7. The solar cell according to claim 1, wherein The second P-type doped emitter is also located in the non-metallic contact area.

8. The solar cell according to claim 7, characterized in that The width of the portion of the second P-type doped emitter located in the metal contact area in the predetermined direction is a first width, and the width of the portion of the second P-type doped emitter located in the non-metal contact area in the predetermined direction is a second width. The ratio of the first width to the second width is 0.9~1.1, and the predetermined direction is perpendicular to the thickness direction of the N-type substrate.

9. The solar cell according to claim 1, wherein The width of the portion of the second P-type doped emitter located in the metal contact area in the predetermined direction is a first width, the width of the isolation structure in the predetermined direction is a third width, the first width is smaller than the third width, and the predetermined direction is perpendicular to the thickness direction of the N-type substrate.

10. A photovoltaic module, characterized in that: include: A battery string formed by connecting the solar cells according to any one of claims 1 to 9; an encapsulation layer, used to cover the surface of the battery string; A cover plate is used to cover a surface of the packaging layer away from the battery string.

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