A solar cell and photovoltaic module

Abstract

The application discloses a solar cell and a photovoltaic module, relates to the photovoltaic technical field, and aims to solve the problem of high preparation cost of the solar cell. The solar cell comprises a silicon substrate, a doped semiconductor layer, a passivation anti-reflection layer and a conductive layer. The silicon substrate has two oppositely arranged surfaces. The doped semiconductor layer is arranged on at least one surface of the silicon substrate. The passivation anti-reflection layer is arranged on the surface of the doped semiconductor layer away from the silicon substrate. The conductive layer is arranged on the surface of the passivation anti-reflection layer and forms electrical contact with the doped semiconductor layer. The conductive layer comprises a silver alloy framework and base metal particles. The silver alloy framework has holes, and the base metal particles are embedded in the holes.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and more particularly to a solar cell and a photovoltaic module. Background Technology

[0002] Electrode fabrication is a crucial step in the manufacturing process of crystalline silicon solar cells. Traditional crystalline silicon solar cells primarily use silver-containing pastes to prepare electrodes because silver has excellent electrical conductivity and chemical stability. However, the high price of silver increases the production cost of solar cells accordingly. Summary of the Invention

[0003] The purpose of this invention is to provide a solar cell that maintains the performance of a solar cell while reducing the manufacturing cost of the solar cell.

[0004] In a first aspect, the present invention provides a solar cell, comprising:

[0005] A silicon substrate having two sides that are positioned opposite each other;

[0006] A doped semiconductor layer is located on at least one side of a silicon substrate;

[0007] The passivation antireflection layer is located on the surface of the doped semiconductor layer away from the silicon substrate;

[0008] A conductive layer is located on the surface of the passivation and antireflection layer and forms an electrical contact with the doped semiconductor layer. The conductive layer includes a silver alloy framework and base metal particles. The silver alloy framework has pores, and the base metal particles are embedded in the pores.

[0009] With the above technical solution, the conductive layer of the solar cell includes a silver alloy skeleton and base metal particles, that is, the conductive layer contains base metal. Compared with the existing electrodes prepared with silver paste that does not contain base metal, the conductive layer in this application can maintain the existing conductivity or be basically the same, while using base metal with the same mass of electrode paste, reducing the use of silver paste and reducing the manufacturing cost of solar cell layer.

[0010] In some possible implementations, the base metal particles can be spherical, blocky, or sheet-like in shape or one or more. The shape of the base metal particles ensures sufficient contact area between the particles and the silver alloy framework or doped semiconductor layer, guaranteeing good conductivity.

[0011] In some possible implementations, the surface of the base metal particles has wrinkles, and / or the surface of the silver alloy framework has a terraced structure. The addition of base metal particles reduces the silver content, resulting in fewer metal crystals forming in the conductive layer and doped semiconductor layer. Consequently, the tensile strength between the conductive layer and the doped semiconductor layer surface, or between the conductive layer and the electrical connector, decreases. However, in the conductive layer with added base metal particles, the undulating structure of both the base metal particles and the silver alloy framework surface provides bonding strength between the conductive layer, the doped semiconductor layer, the passivation and antireflection layer, and the electrical connector, increasing the tensile strength between the conductive layer and the doped semiconductor layer surface, as well as with the electrical connector, thereby improving bonding strength and connection reliability.

[0012] In some possible implementations, the surface of the base metal particles is more undulating than that of the silver alloy skeleton surface.

[0013] In some possible implementations, base metal particles are in contact with a doped semiconductor layer;

[0014] And / or, base metal particles are exposed on the surface of the conductive layer away from the doped semiconductor layer;

[0015] And / or, base metal particles are located between the surfaces of the doped semiconductor layer and the conductive layer away from the doped semiconductor layer and do not contact either surface.

[0016] When the above technical solution is adopted, the base metal particles are randomly distributed in the silver alloy skeleton, such as at the top, bottom and / or middle position of the silver alloy skeleton, which can make the wire performance uniform at each position of the conductive layer.

[0017] In some possible implementations, the conductive layer includes a cluster of base metal particles, which is formed by the aggregation of base metal particles connected by oxides, and the number of base metal particles in the cluster is greater than or equal to 2.

[0018] In some possible implementations, the thickness of the oxide is 0.1–10 nm.

[0019] In some possible implementations, the conductive layer includes a collector electrode and a bus electrode, which are connected together; the collector electrode contains base metal particles, while the bus electrode does not contain base metal particles; or, both the collector electrode and the bus electrode contain base metal particles.

[0020] With the above technical solution, the current collector electrode forms contact with the doped semiconductor layer, responsible for collecting charge carriers. The bus electrode is in electrical contact with the current collector electrode, responsible for collecting the charge carriers collected by the current collector electrode and transporting them to the outside of the solar cell. Furthermore, the bus electrode incorporates base metal particles with a rougher surface compared to the silver alloy framework. This improves the surface roughness of the bus electrode to a certain extent, enhancing the bonding force between it and conductive adhesives or electrical connectors. Therefore, compared to silver paste electrodes, this method reduces costs by decreasing the amount of silver material used in the conductive layer, thus ensuring better reliability of the solar cell when connected in series.

[0021] In some possible implementations, the height of the bus electrode is less than or equal to the height of the collector electrode in the thickness direction of the silicon substrate.

[0022] With the above technical solution, the height of the current collector electrode is equal to or greater than the height of the current collector electrode, which can meet the function of collecting and transmitting charge carriers of the solar cell while reducing the amount of conductive layer material and lowering the cost.

[0023] In some possible implementations, the base metal particles are nickel particles. Nickel particles are not only much cheaper than silver, but also have superior conductivity and bonding performance with solar cells and electrical connectors, which can reduce the manufacturing cost of solar cells while maintaining existing conductivity and cell performance.

[0024] In some possible implementations, the silver content in the conductive layer is greater than the nickel content. By adding less nickel than silver, the fabrication cost of solar cells can be reduced while ensuring good conductivity of the conductive layer.

[0025] In some possible implementations, the base metal particles have a diameter of 0.5 μm to 12 μm. Compared to conventional silver particle size, this optimized base metal particle size can achieve a higher surface area to volume ratio without sacrificing conductivity, reducing the surface area per unit mass of base metal particles, thereby reducing the oxidation probability and improving the adhesion strength and long-term stability of the conductive layer in the photovoltaic cell.

[0026] In some possible implementations, the two sides of the silicon substrate disposed opposite each other include a first side and a second side, the first side being provided with a pyramid-shaped textured structure, the pyramid-shaped textured structure including a apex and multiple side surfaces;

[0027] In this process, some base metal particles in the conductive layer are located near the apex of the pyramid-shaped textured structure and / or at least one side of the pyramid-shaped textured structure.

[0028] In some possible implementations, the second side includes a doped semiconductor layer and a tunneling oxide layer, the tunneling oxide layer being located between the silicon substrate and the doped semiconductor layer, the tunneling oxide layer and the doped semiconductor layer forming a tunneling passivation contact structure, the tunneling passivation contact structure partially or entirely covering the second side of the silicon substrate.

[0029] In some possible implementations, the doped semiconductor layer includes a first doped semiconductor layer and a second doped semiconductor layer disposed on one side of the silicon substrate, the first doped semiconductor layer and the second doped semiconductor layer having opposite conductivity types; the passivation antireflection layer includes a first passivation antireflection layer located on the first doped semiconductor layer and a second passivation antireflection layer located on the second doped semiconductor layer.

[0030] With the above technical solution, a first doped semiconductor layer and a second doped semiconductor layer with opposite conductivity types are formed on one side of the silicon substrate. Both the first doped semiconductor layer and the second doped semiconductor layer form a tunneling passivation contact structure with the tunneling oxide layer. This solar cell is a back contact cell with a tunneling passivation contact structure, which has the advantages of both a tunneling passivation contact structure and a back contact cell. The positive and negative electrodes of the back contact cell are located on the back side, which eliminates the blocking of light by the electrodes, can increase the short-circuit current, and improve the open-circuit voltage.

[0031] In some possible implementations, the conductive layer includes a first conductive layer and a second conductive layer. The first conductive layer is located on the surface of the first passivation antireflection layer away from the silicon substrate and forms an electrical contact with the first doped semiconductor layer. The second conductive layer is located on the surface of the second passivation antireflection layer away from the silicon substrate and forms an electrical contact with the second doped semiconductor layer. The first doped semiconductor layer is p-type doped, and the content of base metal particles in the first conductive layer is less than the content of base metal particles in the second conductive layer.

[0032] In some possible implementations, the conductive layer includes a first conductive layer and a second conductive layer. The first conductive layer is located on the surface of the first passivation antireflection layer away from the silicon substrate and forms an electrical contact with the first doped semiconductor layer. The second conductive layer is located on the surface of the second passivation antireflection layer away from the silicon substrate and forms an electrical contact with the second doped semiconductor layer. The first doped semiconductor layer is p-type doped, and the width of the first conductive layer is greater than the width of the second conductive layer along the extension direction perpendicular to the conductive layer.

[0033] In a second aspect, the present invention also provides a photovoltaic module, comprising a plurality of battery strings, each battery string including a plurality of solar cells and an electrical connector, wherein the solar cells are as described in any of the preceding claims, and the electrical connectors are electrically connected to a conductive layer.

[0034] The conductive layer of this photovoltaic module incorporates base metal particles. Compared to silver alloys, base metal particles have a greater surface roughness, resulting in better adhesion when making electrical connections with electrical connectors. This increases the bonding force between the electrical connectors and the conductive layer, reduces the possibility of electrical connectors detaching, and enhances the reliability of the photovoltaic module.

[0035] In some possible implementations, the electrical connector and the conductive layer are electrically connected via conductive adhesive. Because conductive adhesive has better wettability during the soldering process, it enables full contact between the electrical connector and the conductive layer, reducing the risk of poor soldering and improving the reliability of the conductive connection. Furthermore, the conductive layer, due to the addition of base metal particles, has a greater surface roughness, resulting in better adhesion when in contact with the conductive adhesive, thus increasing the bonding strength between the electrical connector and the conductive layer. Attached Figure Description

[0036] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0037] Figure 1 This is a schematic diagram of the structure of a solar cell provided in an embodiment of the present invention;

[0038] Figure 2 A schematic diagram of the microstructure of the conductive layer of a solar cell provided in an embodiment of the present invention;

[0039] Figure 3 This is another microstructure diagram of the conductive layer of a solar cell provided in an embodiment of the present invention;

[0040] Figure 4 This is another microstructure diagram of the conductive layer of a solar cell provided in an embodiment of the present invention;

[0041] Figure 5 This is another schematic diagram of the conductive layer of a solar cell provided in an embodiment of the present invention;

[0042] Figure 6 This is a schematic diagram of another solar cell structure provided in an embodiment of the present invention;

[0043] Figure 7 This is a schematic diagram of another type of solar cell provided in an embodiment of the present invention.

[0044] Reference numerals in the figures: 1 is silicon substrate, 2 is doped semiconductor layer, 21 is first doped semiconductor layer, 22 is second doped semiconductor layer, 3 is conductive layer, 31 is silver alloy skeleton, 311 is hole, 32 is base metal particle, 4 is passivation antireflection layer, 41 is first passivation antireflection layer, 42 is second passivation antireflection layer, and 5 is tunneling oxide layer. Detailed Implementation

[0045] To make the technical problems, solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0046] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0047] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. "Several" means one or more, unless otherwise explicitly specified.

[0048] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention 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. Therefore, they should not be construed as limitations on this invention.

[0049] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0050] Electrode fabrication is a crucial step in the manufacturing process of crystalline silicon solar cells. Traditional crystalline silicon solar cells primarily use silver-containing pastes to prepare electrodes because silver has excellent electrical conductivity and chemical stability. However, the high price of silver increases the production cost of solar cells accordingly.

[0051] In view of this, such as Figures 1-3As shown, an embodiment of the present invention provides a solar cell, including a silicon substrate 1, a doped semiconductor layer 2, a passivation antireflection layer 4, and a conductive layer 3; wherein, the silicon substrate 1 has two opposing sides; the doped semiconductor layer 2 is located on at least one side of the silicon substrate 1, and on the same side of the silicon substrate 1, the doped semiconductor layer 2 can completely cover the surface of the silicon substrate 1, or it can partially cover the surface of the silicon substrate 1; the passivation antireflection layer 4 is located on the surface of the doped semiconductor layer 2 away from the silicon substrate 1; the conductive layer 3 is located on the surface of the passivation antireflection layer 4 and forms an electrical contact with the doped semiconductor layer 2, wherein the conductive layer 3 includes a silver alloy skeleton 31 and base metal particles 32, the silver alloy skeleton 31 has holes 311, and the base metal particles 32 are embedded in the holes 311.

[0052] It should be noted that the silver alloy skeleton 31, as Figure 2 and Figure 3 As shown, this is a solidified structure formed by the solidification of a slurry composed mainly of silver and one or more other elements such as Si, B, Bi, Pb, and Te after high-temperature melting. The silver alloy framework may still contain portions where the morphology of the unsintered silver particles can be discerned. These silver particles have a diameter range of 1–5 μm, specifically 1 μm, 2 μm, 3 μm, 4 μm, and 5 μm. Particle size refers to the distance between the two furthest points within a silver particle. The morphology of the silver alloy framework 31 can be characterized using methods such as scanning electron microscopy (SEM). For example, a top view of the conductive layer 3 can be used, and the particle size can be measured in the morphology image. The particle size can be the size of a single silver particle or the average size of multiple silver particles. The silver content in the silver alloy skeleton 31 is greater than 50%. After natural solidification, irregular holes 311 are formed in the silver alloy skeleton 31. Base metal particles 32 are embedded in some holes 311. One or more base metal particles 32 can be embedded in a hole 311. Part of the surface of the base metal particles 32 is metallurgically bonded to the silver alloy skeleton 31. There are gaps between the base metal particles 32 and the inner wall of the holes 311, so that the conductive layer 3 forms a non-dense alloy layer.

[0053] When the above technical solution is adopted, the conductive layer 3 of the solar cell includes a silver alloy skeleton 31 and base metal particles 32. That is, the conductive layer 3 contains base metal. Compared with the existing electrodes made of silver paste without base metal, the conductive layer 3 in this application can maintain the existing conductivity or basically the same, and maintain the cell efficiency, while using base metal with the same mass of electrode paste, reducing the amount of silver paste used and reducing the manufacturing cost of solar cell layer.

[0054] It should be noted that the conductive layer on the solar cell can be a partial conductive layer including the silver alloy skeleton 31 and base metal particles 32, or it can be the entire conductive layer including the silver alloy skeleton 31 and base metal particles 32.

[0055] like Figure 2 and Figure 3 As shown, in some embodiments, the base metal particles 32 include one or more of the following shapes: spherical, blocky, and sheet-like. It should be noted that the spherical shape is similar to a sphere, but not a standard sphere, and the surface of the base metal particles 32 is an uneven surface. Similarly, the blocky shape is similar to a rectangular block structure, but not a standard rectangular block, and the sheet-like shape is similar to a flat sheet structure, but not a standard sheet structure. The base metal particles 32 can also be any three-dimensional shape, not limited to the types mentioned above. The shape of the base metal particles 32 ensures sufficient contact area between the base metal particles 32 and the silver alloy framework 31 or the doped semiconductor layer 2, guaranteeing good conductivity.

[0056] In some embodiments, such as Figure 2 and Figure 3 As shown, the surface of the base metal particle 32 has wrinkles, such as Figure 4 As shown, the surface of the silver alloy skeleton has a terraced structure, that is, there is a textured structure with striped stepped or wavy cross-sections on the surface of the silver alloy skeleton 31 (such as...). Figure 4 (As shown in the dashed box). In the above technical solution, the undulating structure of the base metal particles and the silver alloy skeleton surface can provide the bonding force between the conductive layer 3, the doped semiconductor layer, the passivation antireflection layer, and the electrical connectors, preventing the conductive layer 3 from falling off.

[0057] In some embodiments, the surface of the base metal particles 32 has a greater degree of undulation than the surface of the silver alloy framework 31. The comparison of undulation can be a comparison of the number of protrusions and / or depressions; a comparison of the degree of protrusion and / or depression; a comparison of the disorder of the arrangement of protrusions and / or depressions; in another case, a comparison of the height of the protrusions and / or the depth of the depressions; a comparison of the complexity of the morphology; or in other words, the surface of the base metal particles 32 has a greater degree of undulation than the surface of the silver alloy framework 31. That is, the surface of the base metal particles 32 is rougher than the surface of the silver alloy framework 31. This can be determined qualitatively, for example, by comparing the depth of the depressions on the surface of the silver alloy framework 31 with the depth of the depressions on the surface of the base metal particles 32. Compared to electrodes formed from existing silver paste, the addition of base metal particles reduces the silver content, resulting in fewer metal crystals between the silver in the conductive layer and the doped semiconductor layer, or a smaller contact area between the silver alloy skeleton in the conductive layer and the doped semiconductor layer. This reduces the tensile strength between the conductive layer and the doped semiconductor layer surface, or between the conductive layer and the electrical connector. However, in the conductive layer 3 with added base metal particles 32, the wrinkled surface of the particles increases the tensile strength between the conductive layer 3 and the doped semiconductor layer 2 surface, as well as with the electrical connector, thereby improving the bonding strength and reliability between the conductive layer 3 and the doped semiconductor layer 2 and the electrical connector. The wrinkles on the surface of the base metal particles 32 are adhered oxides, such as one or more of silicon oxide, lead oxide, bismuth oxide, nickel oxide, or aluminum oxide.

[0058] In some embodiments, such as Figure 2 and Figure 3As shown, the base metal particles 32 are randomly distributed in the silver alloy framework 31, mainly in the following three distribution positions: First, the base metal particles 32 are located close to and in contact with the doped semiconductor layer 2 in the silver alloy framework 31. Correspondingly, the holes 311 are located in the silver alloy framework 31 near the doped semiconductor layer 2, and the openings of the holes 311 face the doped semiconductor layer 2. Second, the base metal particles 32 are located far from the doped semiconductor layer 2 in the silver alloy framework 31. The base metal particles 32 are exposed on the surface of the conductive layer 3 away from the doped semiconductor layer 2. The base metal particles 32 can be slightly lower than the surface of the conductive layer 3 away from the doped semiconductor layer 2, or flush with or exposed on the surface of the conductive layer 3 away from the doped semiconductor layer 2. Correspondingly, the holes 311 are located on the surface of the conductive layer 3 away from the doped semiconductor layer 2, and the openings of the holes 311 face away from the doped semiconductor layer 2. The third type involves base metal particles 32 located between two opposing surfaces of the conductive layer 3 without contacting these surfaces. These two surfaces are the surface close to the doped semiconductor layer 2 and the surface away from the doped semiconductor layer 2, respectively. Correspondingly, the holes 311 are located inside the silver alloy framework 31 and are closed holes. Base metal particles 32 can be located in one or more of the above three distribution positions, in any combination, and randomly distributed.

[0059] When the above technical solution is adopted, the base metal particles 32 are randomly distributed in the conductive layer 3, such as at the top, bottom and / or middle position of the conductive layer 3. The base metal particles 32 can make electrical contact with the silver alloy skeleton 31 at multiple positions to form a carrier transport channel, thereby making the electrical performance of each position of the conductive layer 3 uniform.

[0060] In some embodiments, the conductive layer 3 includes a cluster of base metal particles, which is formed by the aggregation of base metal particles 32, and the number of base metal particles 32 in the cluster is greater than or equal to 2. The aggregated base metal particles consist of base metal particles at least partially connected by oxides, which can achieve dense connection, effectively reduce the interfacial contact resistance between base metal particles while maintaining high continuity of conductive path, and significantly improve the overall current carrying capacity of base metal particles.

[0061] In some embodiments, the thickness of the oxide is 0.1–1000 nm, for example, it can be 0.1 nm, 1 nm, 5 nm, 10 nm, 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, or a range consisting of any two of the above values. If the thickness is too thin, it is difficult to form a continuous coverage, making the connection regions between the base metal particles 32 more susceptible to oxidation, resulting in decreased stability. If the thickness is too thick, the interfacial resistance between adjacent base metal particles 32 increases, thereby degrading conductivity. When the oxide thickness is set within the above range, charge carriers can pass through the connection regions of the thinner base metal particles 32, forming conductive pathways between adjacent base metal particles 32, thereby reducing the hindering effect of the base metal particles 32 on conductivity.

[0062] It should be noted that the thickness of the oxide can be understood as the length in any tangent direction perpendicular to the connection area of ​​the adjacent base metal particles 32. Here, any tangent can be understood as the tangent of any one of the adjacent base metal particles 32.

[0063] In some embodiments, the conductive layer includes a current collector electrode and a bus electrode. The current collector electrode is also called a fine grid, and the bus electrode is also called a main grid. The current collector electrode forms a contact with the doped semiconductor layer and is responsible for collecting charge carriers. The bus electrode is in electrical contact with the current collector electrode and is responsible for collecting the charge carriers collected by the current collector electrode and transporting them to the outside of the solar cell. The current collector electrode contains base metal particles, and the bus electrode does not contain base metal particles; or, the current collector electrode does not contain base metal particles, and the bus electrode contains base metal particles; or, both the current collector electrode and the bus electrode contain base metal particles.

[0064] When employing the above technical solutions, for example, if base metal particles are added to the current collector electrode while the current collector electrode does not contain base metal particles, the current collector electrode can maintain its existing conductivity or essentially the same level, as well as its cell efficiency, while using base metals with the same mass of electrode paste, reducing the amount of silver paste used and lowering the manufacturing cost of the solar cell layer. Since no base metal paste is added, the current collector electrode can still maintain its original contact performance and tensile strength, especially at the junction of the current collector electrode and the current collector electrode. As another example, if both the current collector electrode and the current collector electrode contain base metal particles, the addition of base metal particles with a rougher surface compared to the silver alloy skeleton can improve the surface roughness of the current collector electrode to a certain extent, increasing the bonding force between the current collector electrode and the conductive adhesive or electrical connector when making electrical connections. Therefore, compared to silver paste electrodes, by reducing the amount of silver material used in the conductive layer to reduce costs, the reliability of the solar cell in series can be better guaranteed.

[0065] In some embodiments, the height of the bus electrode is less than or equal to the height of the current collector electrode in the thickness direction of the silicon substrate. Functionally, the bus electrode is mainly used to collect charge carriers in the current collector electrode and connect them to electrical connectors, while the current collector electrode is mainly used to collect charge carriers generated in the solar cell substrate. Thus, setting the height of the bus electrode to be less than or equal to that of the current collector electrode can reduce the amount of conductive layer material used and lower costs while satisfying the functions of collecting and transporting charge carriers in the solar cell.

[0066] In some embodiments, the bus electrode can be a continuous or discontinuous main gate, pad, end lines corresponding to the two ends near the collector electrode, or a thickened section on the collector electrode, as long as it can be electrically connected to the collector electrode and conductively connected to an electrical connector, such as a solder strip. Different forms of bus electrodes can increase the bonding area and bonding strength between the conductive layer and the electrical connector.

[0067] In some embodiments, the base metal particles 32 are nickel metal particles. That is, the added base metal is nickel. Nickel is not only much cheaper than silver, but also has excellent conductivity and bonding performance with solar cells and electrical connectors, which is not much different from silver. It can reduce the manufacturing cost of solar cells while maintaining the existing conductivity and cell efficiency.

[0068] The following table lists a comparison of the performance parameters of solar cells with conductive layer 3 containing nickel metal particles and those with conductive layer 3 prepared from existing electrode pastes that do not contain nickel metal particles, as shown in Tables 1, 2, and 3:

[0069] Table 1. Performance comparison of solar cells with and without nickel metal particles in the back current collector electrode.

[0070]

[0071] As shown in Table 1, by testing multiple solar cells in each experimental group, the average performance parameters of the cells in each experimental group were obtained. The current collector electrode (also known as the grid) on the back of the solar cell adopts the structure of the conductive layer in this application, that is, it contains nickel metal particles. Compared with the one without nickel metal particles, the cell efficiency is not much different, and other cell performance remains basically unchanged. That is, the conductive layer with added nickel metal particles maintains the existing cell performance and cell efficiency or remains basically unchanged. Moreover, since the base metal nickel is used, the cost of nickel is much lower than that of silver, thus reducing the manufacturing cost of solar cells.

[0072] Table 2. Performance Comparison of Solar Cells with and without Nickel Particles in the Back Busbar Electrode

[0073]

[0074] As shown in Table 2, by testing multiple solar cells in each experimental group, the average value of the battery performance parameters in each experimental group was obtained. The conductive layer structure in this application is adopted in the busbar (also known as the main grid) on the back of the solar cell, which contains nickel metal particles. Compared with the absence of nickel metal particles, the battery efficiency is improved, while other battery performance remains basically unchanged. That is, the conductive layer with added nickel metal particles maintains the existing battery performance and battery efficiency or remains basically unchanged. Moreover, since base metal nickel is used, the cost of nickel is much lower than that of silver, thus reducing the manufacturing cost of solar cells.

[0075] Table 3. Performance Comparison of Solar Cells with and without Nickel Particles in the Front Busbar Electrode

[0076]

[0077] As shown in Table 3, by testing multiple solar cells in each experimental group, the average value of the battery performance parameters in each experimental group was obtained. The conductive layer structure in the front busbar (also known as the main grid) of the solar cell adopts the structure of the present application, which contains nickel metal particles. Compared with the structure without nickel metal particles, the battery efficiency is improved, while other battery performance remains basically unchanged. That is, the conductive layer with added nickel metal particles maintains the existing battery performance and battery efficiency or remains basically unchanged. Moreover, since base metal nickel is used, the cost of nickel is much lower than that of silver, thus reducing the manufacturing cost of solar cells.

[0078] Furthermore, Tables 1, 2, and 3 show that choosing to use the conductive layer structure of this application, which includes nickel metal particles, in the current collector electrode or the bus electrode can reduce the manufacturing cost of solar cells while maintaining battery performance and efficiency.

[0079] Of course, base metals such as aluminum, copper, and zinc can also be used, all of which can reduce the manufacturing cost of solar cells. However, compared to nickel, adding a conductive layer of nickel metal is better at maintaining battery performance and efficiency.

[0080] In some embodiments, the silver content in the conductive layer is greater than the nickel content. Specifically, the mass fraction of silver in the conductive layer is greater than the mass fraction of nickel. By adding nickel in a lower content than silver, the manufacturing cost of solar cells can be reduced while ensuring good cell performance and efficiency in the conductive layer.

[0081] It should be noted that the silver and nickel content in the conductive layer can be measured using techniques commonly used in the art. For example, elemental analysis can be performed on the conductive layer using a scanning electron microscope (SEM) combined with energy dispersive spectroscopy (EDS) to conduct point, line, or area scans, revealing the spatial distribution of each element. Elemental distribution can also be tested in a cross-sectional image including the conductive layer. This cross-section can be obtained by cutting the solar cell at an angle to the direction of the conductive layer's extension, such as 90° (i.e., parallel to the width of the conductive layer) or 120°, and then measuring the resulting SEM image. Alternatively, a single sub-region can be selected within the corresponding area of ​​the conductive layer, and the elemental distribution within that sub-region can be characterized using EDS area scanning to obtain the proportion of metal elements within that sub-region, thus determining the metal element content within that corresponding region of the conductive layer. Alternatively, multiple sub-regions of the same area can be selected in the corresponding region of the conductive layer, and the element distribution in each sub-region of the same area can be characterized by EDS surface scanning to obtain the proportion of metal elements in each sub-region. The average value can then be taken to obtain the metal element content in the corresponding region of the conductive layer. Here, multiple can be 2, 3, 4, 5, 6, etc.

[0082] In some embodiments, the base metal particles have a particle size of 0.5 μm to 12 μm, where the particle size can be the particle size D in the conductive layer. 90 The particle size ranges from 0.5 μm to 12 μm, specifically 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, and 12 μm. It should be noted that the particle size of the base metal particles does not only refer to spherical particles; blocky and plate-like particles can also be sized using particle size, where the particle size refers to the distance between the two furthest points within the particle. Compared to conventional silver particle sizes, this optimized base metal particle size achieves a higher surface area to volume ratio without sacrificing conductivity, reducing the surface area per unit mass of base metal particles, thereby lowering the oxidation probability and improving the adhesion strength and long-term stability of the conductive layer in photovoltaic cells. Furthermore, the relatively small size of the base metal particles at this diameter allows for the fabrication of fine and precise electrode patterns, improving the accuracy of electrode linewidth and spacing. Conductive layers with smaller base metal particles avoid interruptions and irregularities in the conductive path, reducing electrode resistance and improving current collection efficiency. Conductive layers with smaller base metal particles exhibit less stress concentration, which can reduce electrode cracking caused by stress concentration during solar cell encapsulation and subsequent use. Particle size can be measured using a laser particle size analyzer.

[0083] In some embodiments, the solar cell can be a back-contact cell, a bifacial cell, etc. The back-contact cell can be a finger-interlocked back-contact cell, a heterojunction back-contact cell, a tunneling passivation back-contact cell, or a tunneling passivation and heterojunction hybrid back-contact cell, etc. The bifacial cell can be a heterojunction cell, a tunneling passivation cell, etc. The conductive layer can be applied to all of the above solar cells. Different cell types use different materials and structures for the doped semiconductor layers.

[0084] For example, the silicon substrate 1 can be N-type or P-type monocrystalline silicon, polycrystalline silicon, microcrystalline silicon, etc. The material of the doped semiconductor layer 2 can include doped monocrystalline silicon, doped polycrystalline silicon, doped microcrystalline silicon, doped nanocrystalline silicon, doped amorphous silicon, etc. The material of the passivation and antireflection layer 4 can include silicon oxide, silicon carbide, aluminum oxide, silicon nitride, silicon oxynitride, or titanium oxide, etc. The passivation and antireflection layer 4 can be a single-layer or stacked structure composed of one or more of the above materials. The materials and doping types of the silicon substrate 1 and the doped semiconductor layer 2 are selected appropriately according to the type of cell. For example, when the doped semiconductor layer 2 is doped polycrystalline silicon, it can form a tunneling passivation contact structure with the tunneling oxide layer; when the doped semiconductor layer 2 is doped amorphous silicon, it can form a heterojunction contact structure with intrinsic amorphous silicon. The resulting solar cell can be a back-contact solar cell or a bifacial solar cell with a tunneling passivation contact structure and / or a heterojunction contact structure, without specific limitations.

[0085] like Figure 5 and Figure 7 As shown, in some embodiments, when the doped semiconductor layer 2 includes one or more of doped polycrystalline silicon, doped microcrystalline silicon, and doped nanocrystalline silicon, the solar cell further includes a tunneling oxide layer 5. The tunneling oxide layer 5 is located between the silicon substrate 1 and the doped semiconductor layer 2. The tunneling oxide layer 5 and the doped semiconductor layer 2 form a tunneling passivation contact structure. The tunneling passivation contact structure partially or completely covers the surface of the silicon substrate 1. The solar cell is a tunneling passivation contact solar cell.

[0086] like Figure 5As shown, for a bifacial solar cell, the two opposite sides of the silicon substrate 1 include a first side and a second side. The first side of the silicon substrate 1 has a pyramidal textured structure, which includes a apex and multiple sides, allowing incident light to undergo multiple reflections and refractions on the surface of the silicon substrate 1, resulting in a light-trapping effect. Both sides of the silicon substrate 1 have conductive layers 3 with opposite polarities. The doped semiconductor layers 2 on the same side of the silicon substrate 1 have the same conductivity type, which can be either P-type or N-type doped semiconductor layers. These doped semiconductor layers with different doping types are located on the opposite first and second sides of the silicon substrate 1, forming a bifacial solar cell with a tunneling passivation contact mechanism. In conductive layer 3, some base metal particles 32 are positioned close to the apex and / or at least one side of the pyramid-shaped textured structure. In this case, compared to the polished silicon substrate surface, the silicon substrate surface with the pyramid-shaped textured structure provides a larger contact area with the conductive layer. The base metal particles distributed on the conductive layer surface near the silicon substrate are positioned close to the apex and / or at least one side of the pyramid-shaped textured structure, or in contact with the apex and / or at least one side of the pyramid-shaped textured structure, rather than directly contacting the base of the pyramid-shaped textured structure. This distribution arrangement avoids excessive obstruction of the contact between the silver alloy skeleton and the pyramid-shaped textured structure, reduces the ohmic contact formed by the silver alloy skeleton, and ensures the contact performance between the conductive layer and the surface with the pyramid-shaped textured structure.

[0087] In some embodiments, such as Figure 6 As shown, the tunneling passivation contact structure on the same surface of the silicon substrate 1 can partially cover the surface to form a certain pattern, such as a striped pattern arranged at intervals or a grid pattern of horizontal and vertical intersections. Alternatively, the tunneling passivation contact structure on the same surface of the silicon substrate 1 can cover the entire surface. In the bifacial solar cell, a tunneling oxide layer 5, a doped semiconductor layer 2, a passivation antireflection layer 4, and a conductive layer 3 are sequentially stacked on the first surface of the silicon substrate 1, and a diffusion layer (not shown), a passivation antireflection layer 4, and a conductive layer 3 are sequentially stacked on the second surface of the silicon substrate 1.

[0088] In solar cells with tunneling passivation contact structures, the tunneling oxide layer 5 located between the silicon substrate 1 and the doped semiconductor layer 2 allows electrons to pass through while blocking hole transport, thereby achieving efficient charge separation, reducing interface recombination losses, improving interface passivation, and enhancing photoelectric conversion efficiency. Furthermore, the tunneling oxide layer 5 can prevent metal crystals from penetrating the doped semiconductor layer 2 and entering the silicon substrate 1, avoiding damage to the passivation of the solar cell surface and thus preventing a loss of cell efficiency.

[0089] like Figure 7As shown, for a back-contact solar cell, the doped semiconductor layer 2 includes a first doped semiconductor layer 21 and a second doped semiconductor layer 22 disposed on one side of the silicon substrate 1. The first doped semiconductor layer 21 and the second doped semiconductor layer 22 have opposite conductivity types. The passivation antireflection layer 4 includes a first passivation antireflection layer 41 located on the first doped semiconductor layer 21 and a second passivation antireflection layer 42 located on the second doped semiconductor layer 22. It should be noted that the first passivation antireflection layer 41 and the second passivation antireflection layer 42 can be the same layer structure, can be a single layer structure, and can also cover the isolation trench between the first doped semiconductor layer 21 and the second doped semiconductor layer 22, formed in the same step. Alternatively, the first passivation antireflection layer 41 and the second passivation antireflection layer 42 can be different layer structures, or can only cover the corresponding first doped semiconductor layer 21 and the second doped semiconductor layer 22. The tunneling oxide layer 2 located between the silicon substrate 1 and the doped semiconductor layer 2 can be a single layer structure, or can be disconnected at the isolation trench positions corresponding to the positions of the first doped semiconductor layer 21 and the second doped semiconductor layer 22 respectively. A passivation antireflection layer 4 is provided on the other side (i.e. the front side) of the silicon substrate 1.

[0090] With the above technical solution, a first doped semiconductor layer 21 and a second doped semiconductor layer 22 with opposite conductivity types are formed on one side of the silicon substrate 1. Both the first doped semiconductor layer 21 and the second doped semiconductor layer 22 form a tunneling passivation contact structure with the tunneling oxide layer 5. This solar cell is a back contact cell with a tunneling passivation contact structure, which has the advantages of both a tunneling passivation contact structure and a back contact cell. The positive and negative electrodes of the back contact cell are located on the back side, which eliminates the blocking of light by the electrodes, can increase the short-circuit current, and improve the open-circuit voltage.

[0091] In some embodiments, such as Figure 7 As shown, the conductive layer 3 includes a first conductive layer and a second conductive layer. The first conductive layer is located on the surface of the first passivation and antireflection layer 41 away from the silicon substrate 1, forming an electrical contact with the first doped semiconductor layer 21. The second conductive layer is located on the surface of the second passivation and antireflection layer 42 away from the silicon substrate 1, forming an electrical contact with the second doped semiconductor layer 22. The first and second doped semiconductor layers 21 have opposite doping types; the first doped semiconductor layer 21 is P-type doped, and the content of base metal particles in the first conductive layer is less than that in the second conductive layer. Therefore, when the P-type first doped semiconductor layer 21 generally has a lower doping concentration than the N-type second doped semiconductor layer 22, resulting in poorer contact performance between the first doped semiconductor layer 21 and the first conductive layer structure, by controlling the content of base metal particles in the first conductive layer to be less than that in the second conductive layer, the difference in contact performance between the P-region and the N-region can be reduced, thereby achieving a balance in carrier transport between the N-region and the P-region.

[0092] It should be noted that the base metal particle content can be compared by the number of base metal particles in a unit length or unit volume of conductive layer. For example, take a unit volume of conductive layer and calculate the base metal particles exposed on the surface or cross-section of the conductive layer away from the silicon substrate, or take multiple unit volumes of conductive layer, calculate the base metal particles exposed on the surface or cross-section of the conductive layer away from the silicon substrate, and take the average value to compare the base metal particle content.

[0093] In some embodiments, the conductive layer 3 includes a first conductive layer and a second conductive layer. The first conductive layer is located on the surface of the first passivation and antireflection layer 41 away from the silicon substrate 1 and forms an electrical contact with the first doped semiconductor layer 21. The second conductive layer is located on the surface of the second passivation and antireflection layer 42 away from the silicon substrate 1 and forms an electrical contact with the second doped semiconductor layer 22. The first doped semiconductor layer 21 and the second doped semiconductor layer 22 have opposite doping types. The first doped semiconductor layer 21 is P-type doped, and its width is greater than that of the second conductive layer along the extension direction perpendicular to the conductive layer. Therefore, when the P-type first doped semiconductor layer 21 generally has a lower doping concentration than the N-type second doped semiconductor layer 22, resulting in poorer contact performance between the first doped semiconductor layer 21 and the first conductive layer structure, by adjusting the width of the first conductive layer to be greater than that of the second conductive layer, the contact area between the first conductive layer and the first doped semiconductor layer 21 can be increased, thereby increasing the carrier transport channel and improving the contact performance. This helps to reduce the difference in contact performance between the P-region and the N-region, thus achieving a balance in carrier transport between the N-region and the P-region.

[0094] Based on the solar cells described in any of the above embodiments, this invention also provides a photovoltaic module, which includes multiple cell strings, each cell string including multiple solar cells and electrical connectors. The solar cells are as described in any of the above embodiments, and the electrical connectors are electrically connected to the conductive layer. Specifically, the electrical connectors are electrically connected to the electrical junction portion of the conductive layer.

[0095] Since this photovoltaic module uses the solar cell described in any of the above embodiments, it has the same beneficial effects as any of the above embodiments. The addition of base metal particles to the conductive layer of this photovoltaic module, which have a greater surface roughness than silver alloys, results in better adhesion when electrically connecting with electrical connectors. This increases the adhesion between the electrical connectors and the conductive layer, reduces the possibility of connector detachment, increases the reliability of the photovoltaic module, and lowers the manufacturing cost of the photovoltaic module.

[0096] In some embodiments, the electrical connector and the conductive layer are electrically connected via a bonding material. The bonding material can be a conductive adhesive or other material capable of achieving a conductive connection between the electrical connector and the conductive layer. Because conductive adhesives have better wettability during the soldering process, they enable full contact between the electrical connector and the conductive layer, reducing the risk of incomplete soldering and improving the reliability of the conductive connection. Furthermore, the conductive layer, due to the addition of base metal particles, has a greater surface roughness, resulting in better adhesion when in contact with the conductive adhesive, thus increasing the bonding strength between the electrical connector and the conductive layer.

[0097] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0098] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A solar cell, characterized in that, include: A silicon substrate having two opposing sides; A doped semiconductor layer is located on at least one side of the silicon substrate; A passivation antireflection layer is located on the surface of the doped semiconductor layer away from the silicon substrate; A conductive layer is located on the surface of the passivation and antireflection layer and forms an electrical contact with the doped semiconductor layer. The conductive layer includes a current collector and a current bus, which are connected. The conductive layer includes a silver alloy framework and base metal particles. The silver alloy framework has pores, and the base metal particles are embedded in the pores.

2. The solar cell according to claim 1, characterized in that, The base metal particles may be spherical, blocky, or flake-shaped, or one or more of these shapes.

3. The solar cell according to claim 1, characterized in that, The surface of the base metal particles has wrinkles, and / or the surface of the silver alloy skeleton has a terraced structure.

4. The solar cell according to claim 3, characterized in that, The surface undulation of the base metal particles is greater than that of the silver alloy skeleton surface.

5. The solar cell according to claim 1, characterized in that, The base metal particles are in contact with the doped semiconductor layer; And / or, the base metal particles are exposed on the surface of the conductive layer away from the doped semiconductor layer; And / or, the base metal particles are located between the doped semiconductor layer and the conductive layer on the surface opposite to the doped semiconductor layer and do not contact either surface.

6. The solar cell according to claim 1, characterized in that, The conductive layer includes a cluster of base metal particles, which is formed by the aggregation of base metal particles connected by oxides, and the number of base metal particles included in the cluster is greater than or equal to 2.

7. The solar cell according to claim 6, characterized in that, The thickness of the oxide is 0.1~10 nm.

8. The solar cell according to claim 1, characterized in that, The current collecting electrode contains the base metal particles, while the current bus electrode does not contain base metal particles. Alternatively, both the current collector and the current collector may contain base metal particles.

9. The solar cell according to claim 8, characterized in that, In the thickness direction of the silicon substrate, the height of the bus electrode is less than or equal to the height of the collector electrode.

10. The solar cell according to claim 1, characterized in that, The base metal particles are nickel metal particles.

11. The solar cell according to claim 10, characterized in that, The silver content in the conductive layer is greater than the nickel content.

12. The solar cell according to claim 1, characterized in that, The base metal particles have a particle size of 0.5 μm to 12 μm.

13. The solar cell according to any one of claims 1-12, characterized in that, The silicon substrate has two oppositely arranged sides, including a first side and a second side. The first side is provided with a pyramid-shaped textured structure, which includes a pyramid tip and multiple side surfaces. In this case, a portion of the base metal particles in the conductive layer are located near the apex of the pyramid-shaped velvet structure and / or at least one side of the pyramid-shaped velvet structure.

14. The solar cell according to claim 13, characterized in that, The second side includes the doped semiconductor layer and the tunneling oxide layer. The tunneling oxide layer is located between the silicon substrate and the doped semiconductor layer. The tunneling oxide layer and the doped semiconductor layer form a tunneling passivation contact structure. The tunneling passivation contact structure partially or completely covers the second side of the silicon substrate.

15. The solar cell according to any one of claims 1-12, characterized in that, The doped semiconductor layer includes a first doped semiconductor layer and a second doped semiconductor layer disposed on one side of the silicon substrate, wherein the first doped semiconductor layer and the second doped semiconductor layer have opposite conductivity types. The passivation and antireflection layer includes a first passivation and antireflection layer located on the first doped semiconductor layer and a second passivation and antireflection layer located on the second doped semiconductor layer.

16. The solar cell according to claim 15, characterized in that, The conductive layer includes a first conductive layer and a second conductive layer. The first conductive layer is located on the surface of the first passivation and antireflection layer away from the silicon substrate and forms an electrical contact with the first doped semiconductor layer. The second conductive layer is located on the surface of the second passivation and antireflection layer away from the silicon substrate and forms an electrical contact with the second doped semiconductor layer. Wherein, the doping type of the first doped semiconductor layer is P-type doping, and the content of the base metal particles in the first conductive layer is less than the content of the base metal particles in the second conductive layer.

17. The solar cell according to claim 15, characterized in that, The conductive layer includes a first conductive layer and a second conductive layer. The first conductive layer is located on the surface of the first passivation and antireflection layer away from the silicon substrate and forms an electrical contact with the first doped semiconductor layer. The second conductive layer is located on the surface of the second passivation and antireflection layer away from the silicon substrate and forms an electrical contact with the second doped semiconductor layer. Wherein, the first doped semiconductor layer is P-type doped, and along the extension direction perpendicular to the conductive layer, the width of the first conductive layer is greater than the width of the second conductive layer.

18. A photovoltaic module comprising multiple cell strings, each cell string including multiple solar cells and electrical connectors, characterized in that, The solar cell is a solar cell as described in any one of claims 1-17, and the electrical connector is electrically connected to the conductive layer.

19. The photovoltaic module according to claim 18, characterized in that, The electrical connector is electrically connected to the conductive layer via a bonding material.

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