Solar cell, photovoltaic module and preparation method and device thereof

Abstract

The invention provides a solar cell, a photovoltaic module and a preparation method and device thereof, a substrate is provided with a first surface and a second surface, a copper-based oxide layer is arranged on the first surface of the substrate, a texture structure is formed on the surface of one side, deviating from the substrate, of the copper-based oxide layer, and an antireflection layer is arranged on the surface of one side, deviating from the substrate, of the copper-based oxide layer. The antireflection layer comprises multiple unit film layers which are arranged in a stacked mode, and the refractive indexes of the multiple unit film layers are gradually decreased layer by layer in the direction away from the substrate. In the solar cell, the photovoltaic module and the preparation method and device of the solar cell, the photovoltaic module and the preparation method and device of the solar cell, the antireflection layer is designed to be of the gradient refractive index structure with the refractive index decreasing layer by layer, the optical path of ultraviolet light in the antireflection layer can be effectively prolonged, and high-energy ultraviolet photons which originally damage a substrate are absorbed by the antireflection layer material; or the visible light is converted into long-wave-band visible light through a photoluminescence effect, so that the damage of ultraviolet light to the core structure of the cell is effectively reduced, and the ultraviolet attenuation resistance of the solar cell is remarkably improved.

Description

Technical Field

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

[0002] Photovoltaic power generation is the main form of solar energy utilization. Among them, crystalline silicon solar cells, especially tunneling oxide passivated contact (TOPCon) cells, have high conversion efficiency and good mass production compatibility.

[0003] The core feature of TOPCon (Tunneling Oxide Passivated Contact) solar cells lies in their passivation contact structure, which employs an ultra-thin tunneling oxide layer and a doped polycrystalline silicon layer on the back surface. This effectively reduces the recombination rate on the back surface and improves the open-circuit voltage. However, existing TOPCon cells typically still use a traditional PN junction structure on the front side, combined with an alkaline texturing process to create a pyramidal textured surface to increase light absorption. However, current designs do not possess good resistance to UV degradation, thus posing a challenge to long-term reliability. Summary of the Invention

[0004] Therefore, it is necessary to provide a solar cell, a photovoltaic module, and a method and apparatus for their preparation, in response to the aforementioned technical problems.

[0005] This application provides a solar cell, comprising:

[0006] A substrate having a first surface and a second surface;

[0007] A copper-based oxide layer is disposed on a first surface of the substrate, and a textured structure is formed on the side of the copper-based oxide layer facing away from the substrate.

[0008] An antireflection layer is disposed on the side surface of the copper-based oxide layer facing away from the substrate. The antireflection layer comprises multiple stacked unit films, and the refractive index of the multiple unit films decreases layer by layer along the direction away from the substrate.

[0009] In one embodiment, the first surface is a polished surface; and / or,

[0010] The substrate is a crystalline silicon substrate; and / or,

[0011] The texture structure includes a cone-shaped texture structure.

[0012] In one embodiment, at least some layers of the multilayer unit film are made of the same or different materials; and / or,

[0013] The multilayer unit film includes at least one of a silicon nitride layer and a silicon oxide layer.

[0014] In one embodiment, the antireflective layer includes multiple silicon nitride layers disposed sequentially along a direction away from the substrate and multiple silicon oxide layers disposed sequentially on the outermost silicon nitride layer.

[0015] In one embodiment, the refractive index of the silicon nitride layer is between 2.50 and 2.05.

[0016] In one embodiment, the refractive index of the silicon oxide layer is between 1.70 and 1.40.

[0017] In one embodiment, the thickness of the unit film is between 5 nm and 15 nm.

[0018] In one embodiment, the outermost silicon oxide layer has a textured surface on the side facing away from the substrate.

[0019] In one embodiment, it further includes:

[0020] A front-side gate electrode is disposed through the antireflection layer and in contact with the copper oxide layer, and the front-side gate electrode is spaced apart from the substrate.

[0021] In one embodiment, the thickness of the copper-based oxide layer is between 600 nm and 1000 nm.

[0022] In one embodiment, the polishing process includes alkaline polishing, chemical mechanical polishing, or acid polishing.

[0023] This application provides a method for preparing a solar cell, comprising:

[0024] Provide a base;

[0025] The substrate is then cleaned and activated.

[0026] One side surface of the substrate is polished to form a front polished surface;

[0027] A tunneling oxide layer and a phosphorus-doped polycrystalline silicon layer are sequentially grown on the other side surface of the substrate, and then subjected to high-temperature annealing to form a back functional layer.

[0028] A single-crystal p-type cuprous oxide layer is directionally grown on the polished front surface to obtain a copper-based oxide layer.

[0029] An antireflection layer is deposited on the side of the copper-based oxide layer opposite to the substrate;

[0030] A front-side gate electrode is fabricated on the side of the antireflection layer opposite to the substrate;

[0031] The front-side gate electrode is subjected to sintering treatment.

[0032] In one embodiment, the process parameters for directionally growing single-crystal p-type cuprous oxide on the polished front surface to obtain a copper-based oxide layer include: the deposition precursor is an aqueous solution containing copper ions with a pH value of 9-14, the deposition temperature is 20℃-35℃, and a constant negative voltage of 1V-3V is applied to the substrate during deposition.

[0033] In one embodiment, depositing an antireflective layer on the side of the copper-based oxide layer opposite to the substrate includes:

[0034] A silicon nitride layer is deposited on the copper-based oxide layer;

[0035] A silicon oxide layer is deposited on the surface of the silicon nitride layer away from the substrate;

[0036] The refractive index of the silicon nitride layer to the silicon oxide layer decreases layer by layer in the direction away from the substrate.

[0037] In one embodiment, the reaction gas for depositing the silicon nitride layer is silane and ammonia; and / or,

[0038] The pressure for depositing the silicon nitride layer is 80 Pa-110 Pa; and / or,

[0039] The radio frequency power of the deposited silicon nitride layer is 18000W-26000W; and / or,

[0040] The process temperature for depositing the silicon nitride layer is 400℃-500℃; and / or,

[0041] The silane flow rate for depositing the silicon nitride layer is 500 sccm-4500 sccm; and / or,

[0042] The ammonia flow rate for depositing the silicon nitride layer is 7000 sccm-12500 sccm; and / or,

[0043] The flow rate ratio of silane to ammonia gas for depositing the silicon nitride layer is 1:(2.0-4.5); and / or,

[0044] The reaction gases for depositing the silicon oxide layer are silane and nitrous oxide; and / or,

[0045] The pressure for depositing the silicon oxide layer is 75 Pa-95 Pa; and / or,

[0046] The radio frequency power of the deposited silicon oxide layer is 15000W-18000W; and / or,

[0047] The process temperature for depositing the silicon oxide layer is 400℃-520℃; and / or,

[0048] The silane flow rate for depositing the silicon oxide layer is 300 sccm-1600 sccm; and / or,

[0049] The nitrous oxide flow rate for depositing the silicon oxide layer is 10000 sccm-14000 sccm; and / or,

[0050] The flow rate ratio of silane to nitrous oxide in the deposited silicon oxide layer is 1:(9-17).

[0051] This application provides an apparatus for fabricating a solar cell, comprising:

[0052] A processing module configured to perform cleaning and activation treatment on a substrate and polish the surface of the substrate to form a polished surface;

[0053] A fabrication module is configured to sequentially grow a tunneling oxide layer and a phosphorus-doped polycrystalline silicon layer on the other side surface of the substrate, and perform high-temperature annealing to form a back functional layer.

[0054] A growth module configured to directionally grow a copper-based oxide layer on a polished surface of the substrate;

[0055] A deposition module configured to deposit an antireflection layer on the side of the copper-based oxide layer opposite to the substrate;

[0056] A screen printing module configured to fabricate a front gate electrode on the side of the antireflective layer opposite to the substrate;

[0057] A sintering module configured to perform sintering processing on the front gate electrode.

[0058] This application provides a photovoltaic module, including:

[0059] At least one of the aforementioned solar cells;

[0060] Alternatively, a solar cell prepared by at least one of the methods described above.

[0061] In the aforementioned solar cells, photovoltaic modules, and their fabrication methods and apparatus, in the solar cells, by providing a copper-based oxide layer with a textured structure on the first surface of the substrate, the textured structure can be used to increase the scattering and absorption of incident light, thus achieving a light-trapping effect. Simultaneously, by providing an antireflection layer with a progressively decreasing refractive index on the copper-based oxide layer, a gradual matching of the refractive index of sunlight from the air to the cell interior can be achieved, thereby effectively reducing light reflection loss.

[0062] More importantly, designing the antireflection layer as a gradient refractive index structure with a progressively decreasing refractive index can effectively extend the optical path of ultraviolet light within the antireflection layer. This allows high-energy ultraviolet photons that would otherwise damage the substrate to be absorbed by the antireflection layer material itself, or converted into long-wavelength visible light through photoluminescence. This effectively reduces the damage of ultraviolet light to the core structure of the battery and significantly improves the anti-ultraviolet degradation capability of solar cells. Attached Figure Description

[0063] Figure 1 This is a schematic diagram of the structure of a substrate provided in one embodiment of this application.

[0064] Figure 2 This is a schematic diagram of a structure in which a copper-based oxide layer is formed on the first surface of a substrate, according to an embodiment of this application.

[0065] Figure 3 This is a schematic diagram of a textured structure formed on the surface of a copper-based oxide layer, according to an embodiment of this application.

[0066] Figure 4 This is a schematic diagram of a structure for forming an antireflection layer on the surface of a copper-based oxide layer, according to one embodiment of this application.

[0067] Figure 5 This is a schematic diagram of a structure in which a front-side gate electrode is provided in a copper-based oxide layer and an anti-reflection layer, according to an embodiment of this application.

[0068] Figure 6 This is a schematic diagram of a structure in which a tunneling oxide layer, a phosphorus-doped polycrystalline silicon layer, and an amorphous silicon layer are sequentially formed on the second surface of a substrate, according to an embodiment of this application.

[0069] Figure 7 This is a schematic diagram of the structure of an antireflection layer comprising a silicon nitride layer and a silicon oxide layer, provided in one embodiment of this application.

[0070] Figure label:

[0071] 100, Substrate; 200, Copper-based oxide layer; 300, Anti-reflective layer; 400, Front gate electrode; 500, Tunneling oxide layer; 600, Phosphorus-doped polycrystalline silicon layer; 700, Amorphous silicon layer;

[0072] 101. First surface; 102. Second surface;

[0073] 310. Unit film layer; 311. Silicon nitride layer; 312. Silicon oxide layer. Detailed Implementation

[0074] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0075] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0076] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0077] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0078] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0079] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0080] See Figures 1 to 6 As shown, this application provides a solar cell, including a substrate 100, a copper oxide layer 200, and an antireflection layer 300. The material of the substrate 100 can be any of various semiconductor materials used to fabricate solar cells. For example, the substrate 100 can be a crystalline silicon substrate 100, such as an N-type or P-type monocrystalline silicon or polycrystalline silicon substrate 100. Using a crystalline silicon substrate 100 allows for the utilization of mature silicon-based photovoltaic processes, ensuring the basic performance of the cell. The substrate 100 has a first surface 101 and a second surface 102 disposed opposite to each other, and both the first surface 101 and the second surface 102 of the substrate 100 can be designed as polished surfaces as required. Polishing processes suitable for forming this polished surface can include any one of alkaline polishing, chemical mechanical polishing, or acid polishing. These processes can effectively remove the damaged layer and textured surface of the substrate 100, obtaining a flat and clean polished surface, creating favorable conditions for the subsequent directional growth of the high-quality copper oxide layer 200.

[0081] A copper-based oxide layer 200 can be disposed on the first surface 101 of the substrate 100. When the first surface 101 is a polished surface, it can have a low surface state density, which is beneficial for reducing carrier recombination and providing a good foundation for the subsequent growth of a high-quality copper-based oxide layer 200. The side of the copper-based oxide layer 200 facing away from the substrate 100 can form a textured structure. By providing a textured copper-based oxide layer 200 on the first surface 101 of the substrate 100, the textured structure can be used to increase the scattering and absorption of incident light, thus acting as a light-trapping agent.

[0082] In one embodiment, the textured structure formed on the surface of the copper-based oxide layer 200 may include a conical textured structure, such as a square pyramid or a triangular pyramid structure. This conical textured structure, similar to traditional silicon textured surfaces, can effectively trap incident light, increase the optical path length of light within the battery, and improve the photocurrent. For example, when the copper-based oxide layer 200 is a directionally grown single-crystal cuprous oxide (Cu₂O), its… <100> Crystal faces can naturally form outward-facing triangular pyramidal structures.

[0083] Furthermore, the thickness of the copper-based oxide layer 200 can be designed between 600 nm and 1000 nm, such as 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, and 1000 nm. Controlling the thickness of the copper-based oxide layer 200 within this range ensures sufficient absorption and utilization of incident light while also ensuring that the formed texture structure has appropriate size and morphology to achieve a good light-trapping effect. Simultaneously, this thickness range also facilitates the lateral transport of holes, reducing series resistance. If the thickness is too thin, a complete texture structure may not be formed, or insufficient light absorption may occur; if the thickness is too thick, it may increase bulk recombination and electrical resistance.

[0084] In one embodiment, an antireflection layer 300 is disposed on the side of the copper oxide layer 200 facing away from the substrate 100. The antireflection layer 300 comprises multiple stacked unit films 310, and the refractive index of the multiple unit films 310 decreases layer by layer along the direction facing away from the substrate 100. By constructing the antireflection layer 300 on the copper oxide layer 200 by setting multiple unit films 310 with gradually decreasing refractive index, a gradual matching of the refractive index of sunlight from the air to the inside of the battery can be achieved, thereby effectively reducing light reflection loss.

[0085] More importantly, by designing the antireflection layer 300 as a multilayer unit film layer 310 with a progressively decreasing refractive index, a gradient refractive index structure is constructed. This effectively extends the optical path of ultraviolet light within the antireflection layer 300, allowing high-energy ultraviolet photons that would otherwise damage the substrate 100 to be absorbed by the antireflection layer 300 material itself, or converted into long-wavelength visible light through photoluminescence. This effectively reduces the damage of ultraviolet light to the core structure of the battery and significantly improves the anti-ultraviolet degradation capability of the solar cell.

[0086] In one embodiment, in the multilayer unit film layer 310 constituting the antireflection layer 300, at least some layers of the multilayer unit film layer 310 are made of the same or different materials. This means that the multilayer unit film layer 310 can be made of the same material by changing the process conditions to obtain different refractive indices, such as silicon nitride layers 311 with different densities; or it can be formed by alternating or sequentially stacking two or more different materials. Those skilled in the art can design according to actual needs, and no limitation is made here.

[0087] For example, the multilayer unit film 310 may include at least one of a silicon nitride layer 311 and a silicon oxide layer 312. Silicon nitride (SiNx) and silicon oxide (SiO₂) can serve as passivation and antireflection materials in photovoltaic cells, exhibiting good process compatibility and stability. By adjusting their stoichiometry or density, their refractive index can be easily controlled, thereby meeting the design requirements of gradient refractive index.

[0088] The refractive index of the silicon nitride layer 311 can be designed to be between 2.50 and 2.05. This refractive index range of 2.50 to 2.05 covers typical values ​​from silicon-rich silicon nitride (higher refractive index) to nitrogen-rich silicon nitride (lower refractive index). By adjusting process parameters during PECVD deposition, such as the flow ratio of silane and ammonia, deposition pressure, and power, the refractive index of the silicon nitride layer 311 can be precisely controlled to any value between 2.50, 2.35, 2.20, and 2.05, thereby creating a refractive index gradient.

[0089] The refractive index of the silicon oxide layer 312 can be designed to be between 1.70 and 1.40. This range covers refractive index values ​​from denser silicon oxide (higher refractive index) to more porous or less dense silicon oxide (lower refractive index). The outermost silicon oxide layer can have a refractive index as low as 1.40, very close to the refractive index of air, minimizing Fresnel reflections. Similarly, by adjusting PECVD deposition parameters, such as the flow ratio of silane and nitrous oxide, the refractive index of the silicon oxide layer 312 can be easily controlled to any value between 1.70, 1.55, and 1.40.

[0090] Furthermore, the thickness of each unit film layer 310 constituting the antireflection layer 300 can be designed to be between 5nm and 15nm, specifically 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, 11nm, 12nm, 13nm, 14nm, and 15nm. Controlling the thickness of each unit film layer 310 within this relatively thin range helps to construct a fine refractive index gradient, making the refractive index change closer to a continuous gradual change. This results in excellent antireflection effects and ultraviolet light management capabilities over a wider range of wavelengths and incident angles. Simultaneously, it also helps to balance the stress between the unit film layers 310, improving the adhesion and stability of the unit film layers 310.

[0091] In one embodiment, the high-refractive-index silicon nitride layer 311 can be disposed close to the copper-based oxide layer 200, while the low-refractive-index silicon oxide layer 312 can be disposed away from the substrate 100 to achieve a smooth transition of refractive index from high to low. For example, the antireflective layer 300 may include multiple layers of silicon nitride 311 sequentially disposed along a direction away from the substrate 100 and multiple layers of silicon oxide 312 sequentially disposed on the outermost silicon nitride layer 311, thereby forming a multi-level gradient change of refractive index from high to medium to low.

[0092] Among them, the silicon nitride layer 311 near the substrate 100 has a higher refractive index, for example, between 2.0 and 2.5, which can match the refractive index of the copper oxide layer 200 well and play a good field-effect passivation role. The silicon oxide layer 312 near the air has a lower refractive index, for example, between 1.4 and 1.7, which can achieve a good transition with the refractive index of air (n=1) and play an anti-reflection role. Therefore, in the technical solution of this application, if... Figure 7 As shown, by precisely controlling the number of layers and refractive index of the multilayer silicon nitride layer 311 and the multilayer silicon oxide layer 312, a near-ideal refractive index gradient curve can be constructed, minimizing reflection and enhancing ultraviolet light management.

[0093] In one embodiment, the outermost silicon oxide layer 312 may also have a textured surface facing away from the substrate 100. Therefore, in addition to the gradient change in refractive index of the antireflective layer 300, its outermost surface may also have a light-trapping structure. This textured structure can be a nanoscale pyramid array, etc., which can further reduce surface reflection, especially for large-angle incident light, refracting edge-incident light into the effective area of ​​the battery, thereby further improving the light utilization rate of the battery. This textured structure can be formed by additional etching of the silicon oxide layer 312, or directly obtained through a specific deposition process, which is not limited here.

[0094] In one embodiment, the front gate electrode 400 can penetrate the antireflection layer 300, and the front gate electrode 400 is in direct electrical contact with the copper oxide layer 200. Crucially, the front gate electrode 400 and the substrate 100 are simultaneously spaced apart, a key feature distinguishing this application's technical solution from traditional crystalline silicon cells. In traditional cell structures, the front metal gate directly penetrates the passivation layer and contacts the silicon substrate, leading to severe carrier recombination. In this application's technical solution, current is laterally transmitted to the gate electrode through the copper oxide layer 200. Because a heterojunction is formed between the copper oxide layer 200 (e.g., p-type Cu2O) and the substrate 100 (e.g., n-type silicon), the gate electrode only contacts the copper oxide layer 200 and not the silicon substrate 100. Therefore, front metal-silicon contact recombination is fundamentally prevented, significantly improving the cell's open-circuit voltage and fill factor.

[0095] Continue reading Figures 1 to 6 As shown, this application provides a method for fabricating a solar cell, comprising: providing a substrate 100; cleaning and activating the substrate 100; polishing one side surface of the substrate 100 to form a front polished surface; sequentially growing a tunneling oxide layer 500 and a phosphorus-doped polycrystalline silicon layer 600 on the other side surface of the substrate 100, and performing high-temperature annealing to form a back functional layer; directionally growing single-crystal p-type cuprous oxide on the front polished surface to obtain a copper-based oxide layer 200; depositing an antireflection layer 300 on the side of the copper-based oxide layer 200 away from the substrate 100; fabricating a front grid electrode 400 on the side of the antireflection layer 300 away from the substrate 100; and sintering the front grid electrode 400.

[0096] like Figure 1 As shown, a substrate 100 is first provided. For example, an N-type crystalline silicon wafer can be selected. Next, the substrate 100 is cleaned and activated to remove organic matter, metallic impurities, and the native oxide layer from its surface, and to form dangling bonds or active sites on the surface that facilitate subsequent growth. Then, both sides of the substrate 100 are polished to form a front polished surface and a back polished surface.

[0097] like Figure 2 and Figure 3 As shown, a single-crystal p-type cuprous oxide (Cu2O) can then be grown on the polished surface using directional growth techniques, such as electrochemical deposition, to obtain a copper-based oxide layer 200 with specific crystal orientation and surface texture structure. Those skilled in the art can control the growth conditions according to requirements, enabling the Cu2O to... <111> The crystal planes grow parallel to the surface of substrate 100. <100> The crystal planes extend outward to form a triangular pyramidal texture.

[0098] like Figure 4As shown, an antireflective layer 300 is deposited on the side of the copper oxide layer 200 facing away from the substrate 100. This antireflective layer 300 is the aforementioned multilayer unit film layer 310 structure with a progressively decreasing refractive index. Figure 5 As shown, a front gate electrode 400 is finally fabricated on the side of the antireflective layer 300 facing away from the substrate 100 and sintered to ensure good ohmic contact between the front gate electrode 400 and the copper oxide layer 200, while also ensuring good contact between the back electrode and the front gate electrode. Figure 6 As shown, on the other side surface of the substrate 100, a tunneling oxide layer 500 (such as SiO2), a phosphorus-doped polycrystalline silicon layer 600, and an amorphous silicon layer 700 are grown sequentially and subjected to high-temperature annealing to form a back functional layer (i.e., TOPCon structure).

[0099] In the step of directionally growing a copper-based oxide layer 200 on the front polished surface, specifically in one embodiment, an electrochemical deposition process can be used when directionally growing the copper-based oxide layer 200 on the front polished surface. The process parameters may include: the deposition precursor is an aqueous solution containing copper ions, the pH value is 9-14, the deposition temperature is 20℃-35℃, and a constant negative voltage of 1V-3V is applied to the substrate 100 during deposition.

[0100] The deposition precursor can be a solution of copper sulfate (CuSO4) or copper chloride (CuCl2), with the pH value controlled within an alkaline range of 9 to 14 to ensure stable deposition of cuprous oxide. The deposition temperature is controlled within a room temperature range of 20°C to 35°C to ensure mild process conditions. During deposition, a constant negative voltage of 1V to 3V is applied to the substrate 100, effectively driving copper ions to be reduced and deposited on the cathode (the front side of the substrate 100) to form cuprous oxide crystals. By precisely controlling the above parameters, high-quality single-crystal p-type cuprous oxide layers with specific crystal orientations can be stably obtained.

[0101] In one embodiment, depositing an antireflection layer 300 on the side of the copper oxide layer 200 away from the substrate 100 includes: depositing a silicon nitride layer 311 on the copper oxide layer 200; and depositing a silicon oxide layer 312 on the surface of the silicon nitride layer 311 away from the substrate 100; wherein the refractive index of the silicon nitride layer 311 to the silicon oxide layer 312 decreases layer by layer in the direction away from the substrate 100. Therefore, one or more silicon nitride layers 311 are first deposited on the copper oxide layer 200, and then one or more silicon oxide layers 312 are deposited on the surface of the silicon nitride layer 311 away from the substrate 100. By adjusting the specific process parameters when depositing each unit film layer 310, such as gas flow rate, radio frequency power, deposition pressure, etc., the refractive index from the silicon nitride layer 311 to the silicon oxide layer 312 can be reduced layer by layer in the direction away from the substrate 100. That is, the refractive index of the silicon nitride layer 311 near the substrate 100 is the highest, and the refractive index is lower as you go out, until the refractive index of the outermost silicon oxide layer 312 is the lowest.

[0102] In one embodiment, the reaction gases for depositing the silicon nitride layer 311 are silane and ammonia; the pressure for depositing the silicon nitride layer 311 is 80 Pa-110 Pa; the RF power for depositing the silicon nitride layer 311 is 18000 W-26000 W; the process temperature for depositing the silicon nitride layer 311 is 400 °C-500 °C; the silane flow rate for depositing the silicon nitride layer 311 is 500 sccm-4500 sccm; the ammonia flow rate for depositing the silicon nitride layer 311 is 7000 sccm-12500 sccm; and the silane to ammonia flow rate ratio for depositing the silicon nitride layer 311 is 1:(2.0-4.5). The reaction gases for depositing the silicon oxide layer 312 are silane and nitrous oxide; the pressure for depositing the silicon oxide layer 312 is 75 Pa-95 Pa; the radio frequency power for depositing the silicon oxide layer 312 is 15000 W-18000 W; the process temperature for depositing the silicon oxide layer 312 is 400℃-520℃; the silane flow rate for depositing the silicon oxide layer 312 is 300 sccm-1600 sccm; the nitrous oxide flow rate for depositing the silicon oxide layer 312 is 10000 sccm-14000 sccm; and the flow rate ratio of silane to nitrous oxide for depositing the silicon oxide layer 312 is 1:(9-17).

[0103] For depositing the silicon nitride layer 311, the reactant gases can be silane (SiH4) and ammonia (NH3). The deposition pressure can be controlled between 80 Pa and 110 Pa, the RF power between 18000 W and 26000 W, and the process temperature between 400℃ and 500℃. The refractive index of the silicon nitride layer 311 can be controlled by adjusting the flow rates of silane and ammonia. For example, the silane flow rate can be between 500 sccm and 4500 sccm, and the ammonia flow rate can be between 7000 sccm and 12500 sccm. By controlling the flow rate ratio of silane to ammonia to be 1:(2.0-4.5), the refractive index can be precisely adjusted to target values, such as 2.50, 2.35, 2.20, and 2.05. A higher silane ratio typically yields silicon-rich silicon nitride with a higher refractive index, while a higher ammonia ratio yields nitrogen-rich silicon nitride with a lower refractive index.

[0104] For depositing the silicon oxide layer 312, the reactant gases can be silane (SiH4) and nitrous oxide (N2O). The deposition pressure can be controlled between 75 Pa and 95 Pa, the RF power between 15000 W and 18000 W, and the process temperature between 400 °C and 520 °C. Similarly, the refractive index can be controlled by adjusting the gas flow rate. For example, the silane flow rate can be between 300 sccm and 1600 sccm, and the nitrous oxide flow rate can be between 10000 sccm and 14000 sccm. By controlling the silane to nitrous oxide flow rate ratio to be 1:(9-17), the refractive index of the silicon oxide layer 312 can be precisely adjusted to target values, such as 1.70, 1.55, and 1.40. A higher silane ratio corresponds to a higher refractive index, and a higher nitrous oxide ratio corresponds to a lower refractive index.

[0105] Example 1

[0106] The solar cell of this embodiment includes an N-type crystalline silicon substrate 100, which has a first surface 101 and a second surface 102 opposite to each other. The first surface 101 and the second surface 102 of the substrate 100 are treated with an alkaline polishing process to form a smooth polished surface. A single-crystal p-type cuprous oxide (Cu2O) layer is directionally grown on the first surface 101 of the substrate 100 by electrochemical deposition, serving as a copper-based oxide layer 200.

[0107] The electrodeposition process parameters were as follows: the precursor was a 0.02M CuSO4 solution, the pH was adjusted to 12 with NaOH, the deposition temperature was 28℃, a constant negative voltage of 2V was applied to the substrate, and the deposition thickness was controlled at approximately 800nm. In the grown Cu2O layer, <111> The crystal plane is parallel to the surface of substrate 100, and <100> The crystal planes extend outward, forming a pyramid-like conical texture structure on the side of the Cu2O layer facing away from the substrate 100.

[0108] An antireflection layer 300 is deposited on the surface of the copper oxide layer 200. This antireflection layer 300 comprises, from the inside out, four silicon nitride layers 311 and three silicon oxide layers 312. The refractive indices of the four silicon nitride layers 311 are 2.50, 2.35, 2.20, and 2.05, respectively, and the refractive indices of the three silicon oxide layers 312 are 1.70, 1.55, and 1.40, respectively. The thickness of each unit film layer 310 is 10 nm. The deposition of each unit film layer 310 is performed using a PECVD process. The refractive index of the silicon nitride layer 311 is controlled by adjusting the SiH4 / NH3 flow ratio, for example, 1:2.2, 1:2.8, 1:3.5, and 1:4.2. The refractive index of the silicon oxide layer 312 is controlled by adjusting the SiH4 / N2O flow ratio, for example, 1:10, 1:13, and 1:16. The deposition temperature is 450°C, the RF power is optimized and adjusted within the range of 20,000 to 25,000 W according to the refractive index target, and the pressure is also optimized and adjusted within the range of 80 Pa to 110 Pa according to the refractive index target.

[0109] Subsequently, a front-side gate electrode 400 is fabricated on the antireflection layer 300 via screen printing. This front-side gate electrode 400 penetrates the antireflection layer 300 and forms an electrical contact with the copper-based oxide layer 200. A tunneling oxide layer 500 and a phosphorus-doped polycrystalline silicon layer 600 are sequentially formed on the second surface 102 of the substrate 100, constituting the back-side functional layer. Furthermore, a back-side electrode is fabricated on the second surface 102 of the substrate 100. Finally, the battery is fabricated through a sintering process.

[0110] In the solar cell prepared in this embodiment, the front grid electrode 400 is separated from the substrate 100 by a copper oxide layer 200 and an antireflection layer 300, eliminating direct contact and completely preventing front-side metal-to-metal recombination. Simultaneously, the gradient refractive index antireflection layer 300 not only significantly reduces front-side reflection of sunlight but also promotes the conversion of ultraviolet light to visible light by extending the ultraviolet light path length. This protects the underlying copper oxide layer 200 and the substrate 100, greatly enhancing the cell's resistance to ultraviolet degradation.

[0111] In the above embodiment 1, under UV conditions, the efficiency (ETA / %) is 26.41, the open circuit voltage (UOC / V) is 0.7414, the short circuit current (ISC / A) is 13.926, the fill factor (FF / %) is 85.58, the UV attenuation rate is 0.61%, the UV absorption rate is 98.7%, and the transmittance is 98.5%.

[0112] At UV60, the efficiency (ETA / %) is 26.25, the open-circuit voltage (UOC / V) is 0.7406, the short-circuit current (ISC / A) is 13.921, and the fill factor (FF / %) is 85.57.

[0113] In the comparison group, under UV conditions, the efficiency (ETA / %) was 26.33, the open-circuit voltage (UOC / V) was 0.7395, the short-circuit current (ISC / A) was 13.914, the fill factor (FF / %) was 85.56, the UV attenuation rate was 2.18%, the UV absorption rate was 90.5%, and the transmittance was 98.1%.

[0114] At UV60, the efficiency (ETA / %) is 25.75, the open-circuit voltage (UOC / V) is 0.7376, the short-circuit current (ISC / A) is 13.885, and the fill factor (FF / %) is 85.38.

[0115] As shown above, the efficiency degradation rate of the solar cell in this embodiment after 60 hours of UV aging is only 0.61%, which is much lower than the 2.18% of the traditional TOPCon cell. Moreover, compared with the traditional TOPCon cell, the solar cell in this embodiment not only has a higher initial efficiency, but also exhibits an extremely low efficiency degradation rate after rigorous UV aging, demonstrating excellent resistance to UV damage.

[0116] This application provides a solar cell fabrication apparatus, including a processing module, a fabrication module, a growth module, a deposition module, a screen printing module, and a sintering module. The processing module is configured to clean and activate a substrate 100 and polish its surface to form a polished surface. The fabrication module is configured to sequentially grow a tunneling oxide layer 500 and a phosphorus-doped polycrystalline silicon layer 600 on the other side of the substrate 100 and perform high-temperature annealing to form a back-side functional layer. The growth module is configured to directionally grow a copper-based oxide layer 200 on the polished surface of the substrate 100. The deposition module is configured to deposit an antireflection layer 300 on the side of the copper-based oxide layer 200 facing away from the substrate 100. The screen printing module is configured to fabricate a front-side grid electrode 400 on the side of the antireflection layer 300 facing away from the substrate 100. The sintering module is configured to sinter the front-side grid electrode 400.

[0117] This application provides a photovoltaic module comprising at least one of the aforementioned solar cells. Because the photovoltaic module includes a solar cell with excellent resistance to ultraviolet degradation and high conversion efficiency, it also possesses advantages such as high power generation efficiency, good long-term reliability, and long lifespan, making it adaptable to various outdoor environments, especially areas with strong ultraviolet radiation.

[0118] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0119] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A solar cell, characterized in that, include: A substrate having a first surface and a second surface; A copper-based oxide layer is disposed on a first surface of the substrate, and a textured structure is formed on the side of the copper-based oxide layer facing away from the substrate. An antireflection layer is disposed on the side surface of the copper-based oxide layer facing away from the substrate. The antireflection layer comprises multiple stacked unit films, and the refractive index of the multiple unit films decreases layer by layer along the direction away from the substrate.

2. The solar cell according to claim 1, characterized in that, The first surface is a polished surface; and / or, The texture structure includes a cone-shaped texture structure.

3. The solar cell according to claim 1, characterized in that, At least some layers of the multilayer unit film are made of the same or different materials; and / or, The multilayer unit film includes at least one of a silicon nitride layer and a silicon oxide layer.

4. The solar cell according to claim 3, characterized in that, The antireflective layer includes multiple silicon nitride layers arranged sequentially along a direction away from the substrate, and multiple silicon oxide layers arranged sequentially on the outermost silicon nitride layer.

5. The solar cell according to claim 4, characterized in that, The refractive index of the silicon nitride layer is between 2.50 and 2.

05.

6. The solar cell according to claim 4, characterized in that, The refractive index of the silicon oxide layer is between 1.70 and 1.

40.

7. The solar cell according to claim 4, characterized in that, The thickness of the unit film is between 5 nm and 15 nm.

8. The solar cell according to claim 1, characterized in that, Also includes: A front-side gate electrode is disposed through the antireflection layer and in contact with the copper oxide layer, and the front-side gate electrode is spaced apart from the substrate.

9. The solar cell according to any one of claims 1 to 3, characterized in that, The thickness of the copper-based oxide layer is between 600 nm and 1000 nm.

10. A method for preparing a solar cell, characterized in that, include: Provide a base; The substrate is then cleaned and activated. One side surface of the substrate is polished to form a front polished surface; A tunneling oxide layer and a phosphorus-doped polycrystalline silicon layer are sequentially grown on the other side surface of the substrate, and then subjected to high-temperature annealing to form a back functional layer. A single-crystal p-type cuprous oxide layer is directionally grown on the polished front surface to obtain a copper-based oxide layer. An antireflection layer is deposited on the side of the copper-based oxide layer opposite to the substrate; A front-side gate electrode is fabricated on the side of the antireflection layer opposite to the substrate; The front-side gate electrode is subjected to sintering treatment.

11. The preparation method according to claim 10, characterized in that, The process parameters for directionally growing single-crystal p-type cuprous oxide on the polished front surface to obtain a copper-based oxide layer include: The deposition precursor is an aqueous solution containing copper ions with a pH of 9-14. The deposition temperature is 20℃-35℃. A constant negative voltage of 1V-3V is applied to the substrate during deposition.

12. The preparation method according to claim 10, characterized in that, The deposition of the antireflection layer on the side of the copper-based oxide layer opposite to the substrate includes: A silicon nitride layer is deposited on the copper-based oxide layer; A silicon oxide layer is deposited on the surface of the silicon nitride layer away from the substrate; The refractive index of the silicon nitride layer to the silicon oxide layer decreases layer by layer in the direction away from the substrate.

13. An apparatus for fabricating a solar cell, characterized in that, include: A processing module configured to perform cleaning and activation treatment on a substrate and polish the surface of the substrate to form a polished surface; A fabrication module is configured to sequentially grow a tunneling oxide layer and a phosphorus-doped polycrystalline silicon layer on the other side surface of the substrate, and perform high-temperature annealing to form a back functional layer. A growth module configured to directionally grow a copper-based oxide layer on a polished surface of the substrate; A deposition module configured to deposit an antireflection layer on the side of the copper-based oxide layer opposite to the substrate; A screen printing module configured to fabricate a front gate electrode on the side of the antireflective layer opposite to the substrate; A sintering module configured to perform sintering processing on the front gate electrode.

14. A photovoltaic module, characterized in that, include: At least one solar cell as described in any one of claims 1-9; Alternatively, at least one solar cell prepared by the method of preparing a solar cell as described in claims 10 to 12.

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