Back contact cell front sheet, method of making same, and photovoltaic cell module

Abstract

The application provides a back contact cell front plate, a preparation method thereof and a photovoltaic cell assembly. The back contact cell front plate comprises a reflection reduction layer, a substrate layer, a weather-resistant coating layer and an encapsulation adaptation layer which are sequentially stacked; the material of the reflection reduction layer is selected from nano-scale inorganic oxides, the side surface of the reflection reduction layer away from the substrate layer has an array-arranged concave-convex structure, and the reflectivity of the reflection reduction layer in the wavelength range of 400-1100 nm is less than or equal to 2 %; the material of the substrate layer is selected from glass, and the light transmittance of the substrate layer is greater than or equal to 92 %, and the haze is less than or equal to 0.1 %; the material of the weather-resistant coating layer comprises fluorine-containing polyurethane, ultraviolet absorbers and antioxidants; and the material of the encapsulation adaptation layer is selected from silane-grafted modified ethylene-vinyl acetate. The above back contact cell front plate provided by the application has the advantages of high light utilization, good weather resistance and high encapsulation yield, and provides key technical support for high-efficiency and stable high-power photovoltaic cell assemblies.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and more specifically, to a back-contact cell front panel, its preparation method, and a photovoltaic cell module. Background Technology

[0002] Back-contact (BC) cells, with their fully rear-mounted metal grid lines on both positive and negative electrodes, eliminate light loss caused by front-side grid shading. Their photoelectric conversion efficiency is 2-3 percentage points higher than traditional passivated emitter and back-mounted (PERC) cells, making them one of the core directions for high-efficiency upgrading in the photovoltaic industry. The front panel, acting as the "light-transmitting barrier" of the BC cell module, directly determines the solar incident efficiency. It must also withstand complex outdoor environments such as high and low temperature cycling, ultraviolet radiation, and wind and rain erosion. Its performance directly affects the achievement of the module's 25-year design lifespan.

[0003] Based on the current state of photovoltaic module mass production, existing BC cell front panels still have the following practical application defects: First, the surface reflectivity of commonly used photovoltaic glass in mass production is generally above 3.5%. Although it can be reduced to around 2.0% with a single-layer anti-reflection coating, it still cannot meet the light utilization requirements for high-efficiency power generation of BC cells. Moreover, the single-layer coating is prone to wear and peeling after 1-2 years of outdoor use, leading to a rebound in reflectivity. Second, traditional front panels do not have a specifically designed weather-resistant protective structure. In areas with strong ultraviolet radiation, such as Northwest and Southwest my country, they are prone to damage after 3-5 years of use. The existing front panel exhibits yellowing and edge cracking, with a light transmittance reduction exceeding 8%, directly impacting the module's power generation revenue. Thirdly, the front panel surface hardness is mostly 4H, making it susceptible to scratches from clamps and gravel during module production, handling, and outdoor installation. These scratches not only exacerbate light reflection but may also damage insulation performance, increasing the risk of module leakage. Fourthly, the existing front panel has poor adhesion to the EVA encapsulation film, easily generating bubbles during module lamination due to interfacial tension mismatch. The bubble rate can reach over 1.2%, severely affecting the module's structural stability and leading to premature module failure.

[0004] To solve the above-mentioned technical problems, it is urgent to propose a BC cell front panel and photovoltaic cell module. Summary of the Invention

[0005] The main objective of this invention is to provide a back-contact battery front panel, its preparation method, and a photovoltaic cell module, in order to solve the problems of high light reflectivity, easy yellowing and cracking outdoors, and high lamination bubble rate of the back-contact battery front panel in the prior art, which lead to poor photoelectric conversion efficiency, durability, and yield of photovoltaic cell modules.

[0006] To achieve the above objectives, the present invention provides a back-contact battery front panel, which includes an anti-reflection layer, a substrate layer, a weather-resistant coating, and an encapsulation adapter layer stacked sequentially. The anti-reflection layer is made of nanoscale inorganic oxides, and the surface of the anti-reflection layer away from the substrate layer has an array of uneven structures. The anti-reflection layer has a reflectivity ≤2% in the wavelength range of 400–1100 nm. The substrate layer is made of glass, and its light transmittance is ≥92% and its haze is ≤0.1%. The weather-resistant coating is made of fluorinated polyurethane, ultraviolet absorbers, and antioxidants. The encapsulation adapter layer is made of silane-grafted modified ethylene-vinyl acetate.

[0007] Furthermore, in the array of concave-convex structures, each concave-convex unit is spherical or hemispherical, with a radius of 25–100 nm and a spacing of 100–300 nm between adjacent concave-convex units; and / or, the material of the antireflection layer is selected from a mixture of nano-silica and nano-titanium dioxide, preferably with a weight ratio of (3–5):1 of nano-silica to nano-titanium dioxide; and / or, the thickness of the antireflection layer is 80–120 nm.

[0008] Further, by weight percentage, the weather-resistant coating material comprises 97.0–99.2 wt% fluorinated polyurethane, 0.5–2.0 wt% UV absorber, and 0.3–1.0 wt% antioxidant; and / or, preferably, the fluorinated polyurethane is selected from perfluoropolyether-modified polyurethane and / or fluorocarbon side-chain-modified polyurethane; preferably, the UV absorber is selected from benzotriazole UV absorbers; more preferably 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole. One or more of triazole, 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole and 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole; preferably, the antioxidant is selected from hindered phenolic antioxidants; more preferably, one or more of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] pentaerythritol ester, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl ester, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)triazine and 2,6-di-tert-butyl-4-ethylphenol.

[0009] Furthermore, the thickness of the weather-resistant coating is 30–50 nm; and / or, the pencil hardness of the weather-resistant coating is ≥6H.

[0010] Furthermore, the silane-grafted modified ethylene-vinyl acetate has a silane group weight percentage of 0.2–0.5 wt%; and / or, the melt index of the silane-grafted modified ethylene-vinyl acetate at 190 °C and 2.16 kg is 2.0–3.5 g / 10 min; and / or, the thickness of the encapsulation adapter layer is 50–80 nm; and / or, the surface roughness Ra of the encapsulation adapter layer is 0.05–0.1 μm, the peel strength between the encapsulation adapter layer and the EVA encapsulation film is ≥1.5 N / mm, and the interfacial tension difference between the encapsulation adapter layer and the EVA encapsulation film is ≤5 mN / m.

[0011] Furthermore, the surface flatness of the substrate layer is ≤0.1mm / m; and / or, the thickness of the substrate layer is 2.0~3.2mm; and / or, the thickness of the back contact battery front panel is 2.16~3.43mm.

[0012] To achieve the above objectives, another aspect of the present invention provides a method for preparing the back contact battery front panel provided in this application. The method includes: step S1, preparing a first slurry containing nanoscale inorganic oxides using a sol-gel method; coating the first slurry onto one side surface of a substrate, then performing nanoimprinting, and obtaining a substrate with an anti-reflection layer on its surface after a first curing process; the substrate material is selected from glass; step S2, mixing fluorinated polyurethane, an ultraviolet absorber, an antioxidant, and a solvent to obtain a second slurry; coating the second slurry onto a... On the other side of the substrate, a weather-resistant coating is obtained after a second curing. In step S3, ethylene-vinyl acetate, silane coupling agent and crosslinking agent are mixed to obtain a third slurry. The third slurry is coated on the side of the weather-resistant coating away from the substrate, and then a third curing is performed to form an encapsulation adapter layer, thus obtaining a back contact battery front panel. Alternatively, ethylene-vinyl acetate, silane coupling agent, crosslinking agent and initiator are mixed to obtain a fourth slurry. The fourth slurry is coated on the side of the weather-resistant coating away from the substrate, and then a fourth curing is performed to form an encapsulation adapter layer, thus obtaining a back contact battery front panel.

[0013] Further, the preparation method of the first slurry includes: mixing a precursor with an organic solvent and carrying out a solvothermal reaction to obtain the first slurry; preferably, the precursor is selected from a mixture of tetraethyl orthosilicate and tetrabutyl titanate, or a mixture of tetraethyl orthosilicate and tetraisopropyl titanate; preferably, the average particle size of the nano-sized inorganic oxide is 50-200 nm; preferably, the coating amount of the first slurry is 0.08-0.12 mg / cm³. 2 The preferred method is to use a polydimethylsiloxane template for nanoimprinting; the preferred first curing temperature is 170–190°C and the preferred time is 25–35 min.

[0014] Further, the weight ratio of fluorinated polyurethane, UV absorber, and antioxidant is (97.0–99.2):(0.5–2.0):(0.3–1.0); preferably, the coating amount of the second slurry is 0.03–0.05 mg / cm³. 2 The preferred temperature for the second curing is 140–160°C, and the time is 15–25 min.

[0015] Furthermore, based on the weight percentage of the third slurry, the third slurry comprises 97.0–99.3 wt% ethylene-vinyl acetate, 0.2–0.5 wt% silane coupling agent, 0.2–1.0 wt% crosslinking agent, and the balance being an optional first auxiliary agent.

[0016] Furthermore, based on the weight percentage of the fourth slurry, the fourth slurry comprises 96.5–99.0 wt% ethylene-vinyl acetate, 0.2–0.5 wt% silane coupling agent, 0.2–1.0 wt% crosslinking agent, 0.3–1.5 wt% initiator, and the balance being an optional second auxiliary agent.

[0017] Furthermore, the first and second additives are each independently selected from one or more of leveling agents, defoamers, and antistatic agents.

[0018] Furthermore, the silane coupling agent is selected from one or more of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane; the crosslinking agent is preferably selected from peroxide crosslinking agents and / or isocyanate crosslinking agents; the initiator is preferably selected from one or more of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, tert-butyl peroxide, and azobisisobutyronitrile.

[0019] Furthermore, the coating amount of the third slurry is 0.05–0.08 mg / cm³. 2 The preferred third curing temperature is 130–150°C, and the time is 10–20 min; or, the coating amount of the fourth slurry is 0.05–0.08 mg / cm³. 2 The preferred curing temperature for the fourth stage is 130–150°C, and the curing time is 10–20 min.

[0020] Furthermore, the preparation method of the back contact battery front panel also includes: plasma treatment of the glass substrate to obtain the substrate; preferably, the power of the plasma treatment is 100-200W and the time is 30-60s; preferably, the surface tension of the substrate is ≥45mN / m.

[0021] Another aspect of the present invention provides a photovoltaic cell module, including a front panel, an encapsulating film, a back contact cell and a back panel stacked in sequence. The front panel is selected from the back contact cell front panel provided in this application. The front side of the back contact cell is close to the encapsulating film, the back side of the back contact cell is close to the back panel, and positive and negative grid lines are provided on the back side of the back contact cell.

[0022] By applying the technical solution of this invention, the coordinated matching of materials and structures of each functional layer in the BC cell front panel provided in this application systematically solves the three major technical bottlenecks of high reflection, easy aging, and poor bonding in traditional BC cell front panels, and achieves the triple technical effects of improved light utilization, extended weather resistance life and improved encapsulation yield, providing key technical support for efficient and stable high-power photovoltaic cell modules. Attached Figure Description

[0023] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0024] Figure 1 A cross-sectional structural diagram of the front panel of the back contact battery provided in this application is shown;

[0025] Figure 2 A cross-sectional structural diagram of the photovoltaic cell module provided in this application is shown.

[0026] The above figures include the following reference numerals:

[0027] 100. Back contact battery front panel; 10. Anti-reflective layer; 20. Substrate layer; 30. Weather-resistant coating; 40. Encapsulation adapter layer;

[0028] 200, Encapsulating film; 300, Back contact cell; 400, Backsheet. Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0030] As described in the background section, existing back-contact cell front panels suffer from high light reflectivity, susceptibility to yellowing and cracking outdoors, and high lamination bubble rate, resulting in poor photoelectric conversion efficiency, durability, and yield of photovoltaic cell modules. To address these technical problems, the first aspect of this application provides a back-contact cell front panel 100 (BC cell front panel), such as... Figure 1As shown, the back contact battery front panel 100 includes an antireflective layer 10, a substrate layer 20, a weather-resistant coating 30, and an encapsulation adapter layer 40 stacked sequentially. The antireflective layer 10 is made of nanoscale inorganic oxides, and the surface of the antireflective layer 10 away from the substrate layer 20 has an array of uneven structures. The reflectivity of the antireflective layer 10 in the wavelength range of 400–1100 nm is ≤2%. The substrate layer 20 is made of glass, and its light transmittance is ≥92% and its haze is ≤0.1%. The weather-resistant coating 30 is made of fluorinated polyurethane, ultraviolet absorbers, and antioxidants. The encapsulation adapter layer 40 is made of silane-grafted modified ethylene-vinyl acetate.

[0031] The back-contact cell front panel 100 provided in this application includes an anti-reflection layer 10, a substrate layer 20, a weather-resistant coating 30, and an encapsulation adapter layer 40 stacked sequentially. Compared to existing anti-reflection layers 10 that do not include an array-arranged concave-convex structure, the anti-reflection layer 10 with specific materials and structure in this application can reduce the reflectivity in the 400-1100nm wavelength range to below 2%, reduce incident light loss, and significantly improve the photoelectric conversion efficiency of photovoltaic cell modules.

[0032] Using glass with high light transmittance and low haze as the substrate layer 20 can increase the effective absorption area of ​​the back contact cell (BC cell) for incident sunlight, avoid energy loss caused by light scattering, and improve the photoelectric conversion efficiency of the BC cell. Moreover, the glass material has high mechanical strength, which can ensure the structural stability of the photovoltaic cell module during outdoor installation and transportation, thereby meeting the requirements for impact resistance and wind pressure resistance.

[0033] The weather-resistant coating 30 comprises fluorinated polyurethane, UV absorbers, and antioxidants. Compared to ordinary unmodified polyurethane resin, the fluorinated polyurethane exhibits superior resistance to UV aging, damp heat, salt spray, staining, self-cleaning, and chemical corrosion. The UV absorbers and antioxidants synergistically inhibit UV-induced chain breakage and oxidative degradation, effectively preventing coating cracking and yellowing, thereby enhancing the anti-aging performance of the BC cell front panel. The weather-resistant coating 30 absorbs outdoor UV radiation, delaying the aging of the BC cell front panel and improving the durability and long-term light transmission stability of the photovoltaic module.

[0034] Compared to traditional ethylene-vinyl acetate (EVA), the encapsulation adapter layer 40 provided in this application is made of silane-grafted modified ethylene-vinyl acetate. By grafting silane groups, the interfacial bonding force between the encapsulation adapter layer 40 and the EVA encapsulation film is significantly improved. At the same time, during lamination, the encapsulation adapter layer 40 can fuse with the EVA encapsulation film, reducing the lamination bubble rate and improving the encapsulation reliability and yield of photovoltaic cell modules.

[0035] In summary, the synergistic matching of materials and structures of each functional layer in the BC cell front panel provided in this application systematically solves the three major technical bottlenecks of traditional BC cell front panels: high reflection, easy aging, and poor bonding. It achieves a triple technical effect of improved light utilization, extended weather resistance and lifespan, and improved encapsulation yield, providing key technical support for efficient and stable high-power photovoltaic cell modules.

[0036] In a preferred embodiment, each concave-convex unit in the arrayed concave-convex structure is spherical or hemispherical, with a radius of 25–100 nm and a spacing of 100–300 nm between adjacent units. Using this specific micro / nano concave-convex structure allows for controllable multiple refractions of incident light on the nanoscale morphology surface, reducing reflectivity in the 400–1100 nm wavelength range and minimizing reflection losses, thereby improving the photoelectric conversion efficiency of the photovoltaic module. Simultaneously, it helps prevent rainwater and dust adhesion, improving self-cleaning capabilities and reducing outdoor maintenance costs for the photovoltaic module.

[0037] In a preferred embodiment, the antireflection layer 10 is made of a mixture of nano-silica and nano-titanium dioxide, including but not limited to. Compared to a single type of material, using the mixture of nano-silica and nano-titanium dioxide is beneficial for improving the wear resistance of the antireflection layer 10, and also for reducing the reflectivity in the wavelength range of 400–1100 nm, reducing the loss of incident light, thereby improving the photoelectric conversion efficiency of the photovoltaic cell module.

[0038] In order to further improve the wear resistance of the antireflection layer 10, reduce the reflectivity in the wavelength range of 400-1100nm, reduce the loss of incident light, and improve the photoelectric conversion efficiency of the photovoltaic cell module, preferably, the weight ratio of nano-silica to nano-titanium dioxide is (3-5):1.

[0039] In a preferred embodiment, the thickness of the antireflection layer 10 is 80–120 nm. The thickness of the antireflection layer 10 includes, but is not limited to, the above range. Limiting it to the above range is beneficial for reducing reflectivity in the 400–1100 nm wavelength range, reducing incident light loss, and thereby improving the photoelectric conversion efficiency of the photovoltaic cell module.

[0040] In a preferred embodiment, the antireflection layer 10 has a reflectivity of 1.1% to 1.6% in the wavelength range of 400 to 1100 nm. For example, it can be 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, or any two of the above values.

[0041] In a preferred embodiment, the weather-resistant coating 30, by weight percentage, comprises 97.0–99.2 wt% fluorinated polyurethane, 0.5–2.0 wt% UV absorber, and 0.3–1.0 wt% antioxidant. The content of the fluorinated polyurethane, UV absorber, and antioxidant includes, but is not limited to, the above ranges. Limiting these contents to these ranges is beneficial for leveraging the aging resistance of the fluorinated polyurethane, utilizing the synergistic effect of the UV absorber and antioxidant, improving the aging resistance of the BC cell front panel, thereby enhancing the durability and long-term light transmission stability of the photovoltaic module.

[0042] In order to further leverage the excellent UV aging resistance, damp heat resistance, salt spray resistance, anti-fouling self-cleaning properties, and chemical corrosion resistance of fluorinated polyurethane, and to further improve the aging resistance of the BC cell front panel, and further improve the durability and long-term light transmission stability of photovoltaic cell modules, in a preferred embodiment, the fluorinated polyurethane includes, but is not limited to, one or more of perfluoropolyether modified polyurethane and / or fluorocarbon side-chain modified polyurethane.

[0043] To further improve the aging resistance of the BC cell front panel and enhance the durability and long-term light transmission stability of the photovoltaic module, in a preferred embodiment, the ultraviolet absorber includes, but is not limited to, benzotriazole ultraviolet absorbers. Preferably, the ultraviolet absorber includes, but is not limited to, one or more of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole (UV-P), 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole (UV-326), 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole (UV-328), and 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole (UV-329).

[0044] In order to further improve the aging resistance of the BC cell front panel and further improve the durability and long-term light transmission stability of the photovoltaic cell module, in a preferred embodiment, the antioxidant includes, but is not limited to, hindered phenolic antioxidants.

[0045] To further improve the compatibility between antioxidants and fluorinated polyurethane, further improve the aging resistance of the BC cell front panel, and further improve the durability and long-term light transmission stability of photovoltaic cell modules, preferably, the antioxidants include, but are not limited to, one or more of the following: pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010), octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)triazine, and 2,6-di-tert-butyl-4-ethylphenol.

[0046] In a preferred embodiment, the thickness of the weather-resistant coating 30 is 30–50 nm. The thickness of the weather-resistant coating 30 includes, but is not limited to, the above range. Limiting it to this range is beneficial for improving ultraviolet absorption efficiency and delaying the aging of the BC cell front panel, thereby improving the durability and long-term light transmission stability of the photovoltaic module.

[0047] In a preferred embodiment, the pencil hardness of the weather-resistant coating 30 is ≥6H. The pencil hardness of the weather-resistant coating 30 includes, but is not limited to, the above range. Limiting it to the above range helps to effectively resist scratches during production, handling, and installation, and reduces the risk of light loss and leakage current caused by scratches on the components.

[0048] In a preferred embodiment, the silane-grafted modified ethylene-vinyl acetate contains 0.2 to 0.5 wt% silane groups. The content of silane groups includes, but is not limited to, the above range. Limiting it to this range helps improve the interfacial adhesion between the encapsulation adapter layer 40 and the EVA encapsulation film, reduces lamination bubble rate, and thus helps improve the encapsulation reliability and yield of photovoltaic cell modules.

[0049] In order to further improve the interfacial bonding between the encapsulation adapter layer 40 and the EVA encapsulation film, reduce the lamination bubble rate, and further improve the encapsulation reliability and yield of photovoltaic cell modules, preferably, the melt index of silane grafted modified ethylene-vinyl acetate at 190℃ and 2.16kg is 2.0~3.5g / 10min.

[0050] In a preferred embodiment, the thickness of the encapsulation adapter layer 40 is 50–80 nm. The thickness of the encapsulation adapter layer 40 includes, but is not limited to, the above range. Limiting it to the above range helps to improve the interfacial adhesion between the encapsulation adapter layer 40 and the EVA encapsulation film, reduce the lamination bubble rate, and thus help to improve the encapsulation reliability and yield of photovoltaic cell modules.

[0051] The encapsulation adapter layer 40 provided in this application exhibits superior surface roughness and peel strength with the EVA encapsulation film. In a preferred embodiment, the surface roughness Ra of the encapsulation adapter layer 40 is 0.05–0.1 μm, the peel strength between the encapsulation adapter layer 40 and the EVA encapsulation film is ≥1.5 N / mm, and the interfacial tension difference between the encapsulation adapter layer 40 and the EVA encapsulation film is ≤5 mN / m.

[0052] In a preferred embodiment, the surface flatness of the substrate layer 20 is ≤0.1 mm / m. The surface flatness of the substrate layer 20 includes, but is not limited to, the above range. Limiting it to the above range helps to reduce light scattering loss caused by surface unevenness, thereby helping to improve the photoelectric conversion efficiency of the photovoltaic cell module.

[0053] In a preferred embodiment, the thickness of the substrate layer 20 is 2.0–3.2 mm. The thickness of the substrate layer 20 includes, but is not limited to, the above range. Limiting it to this range helps to suppress insufficient mechanical strength due to excessive thickness or uneven pressure distribution caused by excessive thickness, thereby reducing the risk of bubble formation and poor adhesion of the encapsulation film during the encapsulation process. Combined with the synergistic effect of the weather-resistant coating 30 and the encapsulation adapter layer 40, this contributes to a significant improvement in the overall performance of the BC battery front panel, resulting in high reliability, low degradation, and high yield in long-term outdoor environments.

[0054] In a preferred embodiment, the thickness of the back contact cell front panel 100 is 2.16–3.43 mm. The thickness of the back contact cell front panel 100 includes, but is not limited to, the above range, and limiting it within this range facilitates adaptation to the lamination parameters of existing photovoltaic module lamination equipment.

[0055] The second aspect of this application also provides a method for preparing the back contact battery front panel 100 provided in this application. The method for preparing the back contact battery front panel 100 includes: step S1, preparing a first slurry containing nano-sized inorganic oxides using a sol-gel method; coating the first slurry onto one side surface of a substrate, then performing nanoimprinting, and obtaining a substrate with an anti-reflection layer 10 on its surface after a first curing; the material of the substrate is selected from glass; step S2, mixing fluorinated polyurethane, ultraviolet absorber, antioxidant and solvent to obtain a second slurry; coating the second slurry onto the other side surface of the substrate, and then performing a first curing to obtain a substrate with an anti-reflection layer 10 on its surface; the substrate material is selected from glass; step S2, mixing fluorinated polyurethane, ultraviolet absorber, antioxidant and solvent to obtain a second slurry; coating the second slurry onto the other side surface of the substrate, and then performing a first curing to obtain a substrate with an anti-reflection layer 10 on its surface. After curing, a weather-resistant coating 30 is obtained; in step S3, ethylene-vinyl acetate, silane coupling agent and crosslinking agent are mixed to obtain a third slurry; the third slurry is coated on the side of the weather-resistant coating 30 away from the substrate, and then a third curing is performed to form an encapsulation adapter layer 40, thus obtaining a back contact battery front panel 100; or, ethylene-vinyl acetate (EVA), silane coupling agent, crosslinking agent and initiator are mixed to obtain a fourth slurry; the fourth slurry is coated on the side of the weather-resistant coating 30 away from the substrate, and then a fourth curing is performed to form an encapsulation adapter layer 40, thus obtaining a back contact battery front panel 100.

[0056] A first slurry containing nanoscale inorganic oxides is prepared by sol-gel method and coated on one side of the substrate. After nanoimprinting and first curing, an antireflection layer 10 with a micro-nano uneven structure is formed, which can reduce the reflectivity in the wavelength range of 400-1100nm to below 2% and improve the light absorption efficiency. Subsequently, a second slurry containing the above-mentioned specific components is coated on the other side of the substrate and a weather-resistant coating 30 is formed after a second curing, which can improve the anti-yellowing and anti-aging ability of the BC battery front panel. Finally, a third or fourth slurry containing EVA and silane coupling agent is coated on the side of the weather-resistant coating 30 away from the substrate and a third or fourth curing is performed to graft the silane coupling agent onto the EVA molecular chain in situ, forming an encapsulation adapter layer 40, which improves the interfacial bonding force between the silane coupling agent and the EVA encapsulation film, thus obtaining the BC battery front panel.

[0057] Compared to existing antireflective layers 10 that do not include an array of concave and convex structures, the antireflective layer 10 with specific materials and structures in this application can reduce the reflectivity in the 400–1100 nm wavelength range to below 2%, reducing incident light loss and significantly improving the photoelectric conversion efficiency of photovoltaic modules. Using high-transmittance, low-haze glass as the substrate layer 20 increases the effective absorption area of ​​the BC cell for incident sunlight, avoiding energy loss due to light scattering and improving the photoelectric conversion efficiency of the BC cell. Furthermore, the high mechanical strength of glass ensures the structural stability of the photovoltaic module during outdoor installation and transportation, thus meeting the requirements for impact and wind pressure resistance. The weather-resistant coating 30 comprises fluorinated polyurethane, UV absorbers, and antioxidants. Compared to ordinary unmodified polyurethane resin, the fluorinated polyurethane exhibits superior resistance to UV aging, damp heat, salt spray, staining, self-cleaning, and chemical corrosion. The UV absorbers and antioxidants synergistically inhibit UV-induced chain breakage and oxidative degradation, effectively preventing coating cracking and yellowing, thereby enhancing the anti-aging performance of the BC cell front panel. The weather-resistant coating 30 absorbs outdoor UV radiation, delaying the aging of the BC cell front panel and improving the durability and long-term light transmission stability of the photovoltaic module. Compared to traditional EVA, the encapsulation adapter layer 40, formed by in-situ grafting silane groups, improves the interfacial adhesion between the encapsulation adapter layer 40 and the EVA encapsulation film. Furthermore, during subsequent photovoltaic module lamination, the encapsulation adapter layer 40 can fuse with the EVA encapsulation film, reducing lamination bubble rate and thus improving the encapsulation reliability and yield of the photovoltaic module.

[0058] The preparation method provided in this application is fully compatible with existing mainstream BC cell production lines, requiring no additional specialized equipment, and enables efficient and low-cost large-scale manufacturing of high-performance BC cell front panels.

[0059] In a preferred embodiment, the preparation method of the first slurry includes: mixing a precursor with an organic solvent and carrying out a solvothermal reaction to obtain the first slurry. The solvothermal reaction of the precursor can generate nano-inorganic oxides in situ. Compared to preparing the first slurry using nano-inorganic oxides and solvents, the above-mentioned "in-situ preparation method + direct coating integration" process can improve the dispersibility and compatibility of nano-inorganic oxides in the first slurry, and improve the processability of the first slurry.

[0060] To obtain silica nanoparticles and titanium dioxide nanoparticles, the precursors preferably include, but are not limited to, a mixture of tetraethyl orthosilicate (TEOS) and tetrabutyl titanate (TBOT), or a mixture of tetraethyl orthosilicate and tetraisopropyl titanate (TPOT).

[0061] In a preferred embodiment, the average particle size of the nanoscale inorganic oxide is 50–200 nm. The average particle size of the nanoscale inorganic oxide includes, but is not limited to, the above range. Limiting it to this range is beneficial for the antireflection layer 10 to reduce reflection loss and incident light loss, thereby improving the photoelectric conversion efficiency of the photovoltaic module.

[0062] In order to improve the dispersibility and compatibility of nano-inorganic oxides in the first slurry and improve the processability of the first slurry, in a preferred embodiment, the organic solvent in the first slurry includes, but is not limited to, one or more of anhydrous ethanol, anhydrous isopropyl ester, and propylene glycol methyl ether acetate (PMA).

[0063] In a preferred embodiment, the coating amount of the first slurry is 0.08–0.12 mg / cm³. 2 The amount of the first slurry applied includes, but is not limited to, the range described above. Limiting it to the range is beneficial for the antireflection layer 10 to reduce reflection loss and incident light loss, thereby improving the photoelectric conversion efficiency of the photovoltaic cell module.

[0064] Polydimethylsiloxane (PDMS) has good flexibility and can be used as a template for nanoimprinting, adapting to substrates of different sizes. In a preferred embodiment, a PDMS template is used for nanoimprinting.

[0065] In a preferred embodiment, the first curing temperature is 170–190°C, and the time is 25–35 minutes. The first curing temperature and time include, but are not limited to, the above ranges. Limiting them to the above ranges is beneficial for forming an antireflection layer 10 with a specific micro-nano uneven structure, thereby facilitating the function of the antireflection layer 10 and improving the photoelectric conversion efficiency of the photovoltaic cell module.

[0066] In a preferred embodiment, the weight ratio of fluorinated polyurethane, UV absorber, and antioxidant is (97.0–99.2):(0.5–2.0):(0.3–1.0). This weight ratio includes, but is not limited to, the above range. Limiting it to this range helps to maximize the aging resistance of the fluorinated polyurethane, leverage the synergistic effect of the UV absorber and antioxidant, improve the aging resistance of the BC cell front panel, and thus enhance the durability and long-term light transmission stability of the photovoltaic module.

[0067] In a preferred embodiment, the coating amount of the second slurry is 0.03–0.05 mg / cm³. 2 The coating amount of the second slurry includes, but is not limited to, the above-mentioned range. Limiting it to the above-mentioned range is beneficial to improving the continuity of the weather-resistant coating 30, making the distribution of ultraviolet absorbers and antioxidants more uniform, reducing internal stress, improving the adhesion of the weather-resistant coating 30, thereby giving full play to the role of the weather-resistant coating 30 and improving the aging resistance of the BC battery front panel.

[0068] In a preferred embodiment, the second curing temperature is 140–160°C, and the time is 15–25 minutes. The second curing temperature and time include, but are not limited to, the above ranges. Limiting them to the above ranges is beneficial for improving the coating performance of the weather-resistant coating 30 while improving the curing efficiency, thereby improving the aging resistance of the BC battery front panel.

[0069] In a preferred embodiment, the solvent in the second slurry includes, but is not limited to, butyl acetate and / or propylene glycol methyl ether acetate (PMA).

[0070] In a preferred embodiment, the third slurry comprises, by weight percentage, 97.0–99.3 wt% ethylene-vinyl acetate, 0.2–0.5 wt% silane coupling agent, 0.2–1.0 wt% crosslinking agent, and the balance being an optional first additive. The weight percentages of EVA, silane coupling agent, crosslinking agent, and the first additive in the third slurry include, but are not limited to, the above ranges. Limiting these percentages to the above ranges is beneficial for improving the grafting modification effect of silane groups, increasing raw material utilization, thereby improving the interfacial bonding between the encapsulation adapter layer 40 and the EVA encapsulation film, reducing lamination bubble rate, and thus improving the encapsulation reliability and yield of photovoltaic cell modules.

[0071] In another preferred embodiment, the fourth slurry comprises, by weight percentage, 96.5–99.0 wt% ethylene-vinyl acetate, 0.2–0.5 wt% silane coupling agent, 0.2–1.0 wt% crosslinking agent, 0.3–1.5 wt% initiator, and the balance being an optional second auxiliary agent. The weight percentages of EVA, silane coupling agent, crosslinking agent, and initiator in the fourth slurry include, but are not limited to, the above ranges. Limiting these percentages to the above ranges is beneficial for improving the grafting modification effect of silane groups, increasing raw material utilization, thereby improving the interfacial bonding force between the encapsulation adapter layer 40 and the EVA encapsulation film, reducing lamination bubble rate, and thus improving the encapsulation reliability and yield of photovoltaic cell modules.

[0072] In a preferred embodiment, the first and second additives are each independently including, but not limited to, one or more of leveling agents, defoamers, and antistatic agents.

[0073] To further improve the interfacial bonding between the encapsulation adapter layer 40 and the EVA encapsulation film, and to further reduce the lamination bubble rate, preferably, the silane coupling agent includes, but is not limited to, one or more of γ-aminopropyltriethoxysilane (KH-550), γ-glycidoxypropyltrimethoxysilane (GPTMS), and γ-methacryloyloxypropyltrimethoxysilane (KH-570).

[0074] To further improve the interfacial adhesion between the encapsulation adapter layer 40 and the EVA encapsulation film, and to further reduce the lamination bubble rate, while also increasing the crosslinking density of the encapsulation adapter layer 40, preferably, the crosslinking agent includes, but is not limited to, peroxide crosslinking agents and / or isocyanate crosslinking agents. For example, the peroxide crosslinking agent may be benzoyl peroxide and / or dicumyl peroxide (DCP).

[0075] To further improve the grafting modification effect of silane groups, further improve the interfacial bonding force between the encapsulation adapter layer 40 and the EVA encapsulation film, and further reduce the lamination bubble rate, preferably, the initiator includes, but is not limited to, one or more of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, tert-butyl peroxide, and azobisisobutyronitrile.

[0076] In a preferred embodiment, the coating amount of the third slurry is 0.05–0.08 mg / cm³. 2 The coating amount of the third slurry includes, but is not limited to, the range mentioned above. Limiting it to the range is beneficial to improving processability, enhancing the interfacial bonding between the encapsulation adapter layer 40 and the EVA encapsulation film, and reducing the lamination bubble rate, thereby improving the encapsulation reliability and yield of photovoltaic cell modules.

[0077] In a preferred embodiment, the third curing temperature is 130–150°C, and the time is 10–20 min. The third curing temperature and time include, but are not limited to, the above range. Limiting them to the above range is beneficial to improving the crosslinking density of the encapsulation adapter layer 40, improving the interfacial bonding force between the encapsulation adapter layer 40 and the EVA encapsulation film, and reducing the lamination bubble rate, thereby improving the encapsulation reliability and yield of photovoltaic cell modules.

[0078] In a preferred embodiment, the coating amount of the fourth slurry is 0.05–0.08 mg / cm³. 2 The coating amount of the fourth slurry includes, but is not limited to, the range mentioned above. Limiting it to the range is beneficial to improving processability, enhancing the interfacial bonding between the encapsulation adapter layer 40 and the EVA encapsulation film, and reducing the lamination bubble rate, thereby improving the encapsulation reliability and yield of photovoltaic cell modules.

[0079] In a preferred embodiment, the fourth curing temperature is 130–150°C, and the time is 10–20 min. The fourth curing temperature and time include, but are not limited to, the above range. Limiting them to the above range is beneficial to improving the crosslinking density of the encapsulation adapter layer 40, improving the interfacial bonding force between the encapsulation adapter layer 40 and the EVA encapsulation film, and reducing the lamination bubble rate, thereby improving the encapsulation reliability and yield of photovoltaic cell modules.

[0080] In a preferred embodiment, the preparation method of the back contact battery front panel 100 further includes: plasma treatment of a glass substrate to obtain a substrate. Plasma treatment of the glass substrate helps to improve the adhesion between the substrate and the subsequently prepared weather-resistant coating 30, and prevents the weather-resistant coating 30 from peeling off during high and low temperature (-40°C to 85°C) cycling.

[0081] To further improve the adhesion between the substrate and the weather-resistant coating 30, preferably, the plasma treatment power is 100-200W and the time is 30-60s.

[0082] To further improve the adhesion between the substrate and the weather-resistant coating 30, preferably, the surface tension of the substrate is ≥45mN / m.

[0083] A third aspect of this application also provides a photovoltaic cell module, such as... Figure 2As shown, the photovoltaic module includes a front panel, an encapsulating film 200, a back contact cell 300, and a back panel 400 stacked sequentially. The front panel is selected from the back contact cell front panel 100 provided in this application. The front side of the back contact cell 300 is close to the encapsulating film 200, and the back side of the back contact cell 300 is close to the back panel 400. Positive and negative grid lines are provided on the back side of the back contact cell 300. The synergistic matching of materials and structures of each functional layer in the BC cell front panel provided in this application systematically solves the three major technical bottlenecks of high reflection, easy aging, and poor adhesion of traditional BC cell front panels. It achieves a triple technical effect of improved light utilization, extended weather resistance, and improved encapsulation yield, providing key technical support for high-efficiency and stable high-power photovoltaic modules. Applying the BC cell front panel provided in this application to photovoltaic modules can improve their photoelectric conversion efficiency, durability, and yield.

[0084] In a preferred embodiment, the photovoltaic cell module provided in this application is compatible with BC cells of 166mm, 182mm, and 210mm specifications, and the module lamination bubble rate is ≤0.3%.

[0085] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0086] Example 1

[0087] A method for preparing a back contact battery front panel 100, comprising:

[0088] (1) Prepare the substrate:

[0089] The photovoltaic-grade low-iron glass mass-produced by Xinyi Glass has a thickness of 2.8 mm, a light transmittance of 92.5% in the wavelength range of 400-1100 nm, a haze of 0.08%, and a surface flatness of 0.08 mm / m. The substrate is obtained by plasma treatment with 150 W for 45 s; the surface tension of the substrate is 48 mN / m.

[0090] (2) Preparation of antireflective layer 10:

[0091] TEOS, TBOT, and anhydrous ethanol were mixed and subjected to a solvothermal reaction at 90°C to obtain a first slurry. The weight ratio of nano-sized silica to nano-sized titanium dioxide in the first slurry was 4:1, and the average particle size was 125 nm. The first slurry was then roll-coated onto one side of the substrate prepared in step (1), with a coating amount of 0.1 mg / cm². 2Nanoimprinting was performed using a PDMS template, followed by curing at 180°C for 30 minutes to form an antireflection layer 10 with an array of micro-nano uneven structures on one side. Each uneven unit is hemispherical with a radius of 60 nm, and the spacing between two adjacent uneven units is 200 nm. The antireflection layer 10 has a thickness of 100 nm and a reflectivity of 1.2% in the wavelength range of 400–1100 nm.

[0092] (3) Preparation of weather-resistant coating 30:

[0093] 98.6g of fluorocarbon side-chain modified aliphatic polyurethane resin (number average molecular weight of 50000g / mol), 0.8g of UV-P, 0.6g of antioxidant 1010, and butyl acetate were mixed to obtain a second slurry. The second slurry contained 0.8wt% UV-P and 0.6wt% antioxidant 1010. This second slurry was then roller-coated onto the other side of the substrate prepared in step (1), with a coating amount of 0.04mg / cm². 2 Then, it is cured at 150℃ for 20 minutes to obtain weather-resistant coating 30; the thickness of weather-resistant coating 30 is 40nm, the pencil hardness is 6H, and the light transmittance retention rate is 98.5% after outdoor accelerated aging test (simulating 10 years of outdoor environment);

[0094] (4) Preparation of the encapsulation adapter layer 40:

[0095] 99.0g of ethylene-vinyl acetate, 0.3g of KH-550, and 0.7g of crosslinking agent DCP were mixed to obtain a third slurry; the weight percentage of KH-550 in the third slurry was 0.3wt%; the third slurry was coated on the side of the weather-resistant coating 30 away from the substrate, with a coating amount of 0.065mg / cm². 2 Then, it is cured at 140℃ for 15 minutes to form an encapsulation adapter layer 40, resulting in a product with... Figure 1 The cross-sectional structure shown is of the back contact battery front panel 100. The material of the encapsulation adapter layer 40 is silane-grafted modified ethylene-vinyl acetate, wherein the weight percentage of silane groups is 0.3wt%, the melt index at 190℃ and 2.16kg is 2.8g / 10min, the thickness of the encapsulation adapter layer 40 is 65nm, the surface roughness Ra is 0.08μm, and the peel strength between the encapsulation adapter layer 40 and the EVA encapsulation film is 1.8N / mm.

[0096] Example 2

[0097] A method for preparing a back contact battery front panel 100, comprising:

[0098] (1) Prepare the substrate:

[0099] The photovoltaic-grade low-iron glass mass-produced by Xinyi Glass has a thickness of 2.0 mm, a light transmittance of 92.0% in the wavelength range of 400–1100 nm, a haze of 0.1%, and a surface flatness of 0.1 mm / m. The substrate is obtained by treating it with 100 W plasma for 30 seconds. The surface tension of the substrate is 45 mN / m.

[0100] (2) Preparation of antireflective layer 10:

[0101] TEOS, TPOT, and anhydrous isopropyl ester were mixed and subjected to a solvothermal reaction at 90°C to obtain a first slurry. The weight ratio of nano-sized silica to nano-sized titanium dioxide in the first slurry was 3:1, and the average particle size was 75 nm. The first slurry was then roll-coated onto one side of the substrate prepared in step (1), with a coating amount of 0.08 mg / cm². 2 Nanoimprinting was performed using a PDMS template, followed by curing at 180°C for 30 minutes to form an antireflection layer 10 with an array of micro-nano uneven structures on one side. Each uneven unit is hemispherical with a radius of 25 nm, and the spacing between two adjacent units is 100 nm. The antireflection layer 10 has a thickness of 80 nm and a reflectivity of 1.4% in the wavelength range of 400–1100 nm.

[0102] (3) Preparation of weather-resistant coating 30:

[0103] 99.2g of fluorocarbon side-chain modified aliphatic polyurethane resin (number average molecular weight of 50000g / mol), 0.5g of UV-P, 0.3g of antioxidant 1010, and butyl acetate were mixed to obtain a second slurry. The second slurry contained 0.5wt% UV-P and 0.3wt% antioxidant 1010. This second slurry was then roller-coated onto the other side of the substrate prepared in step (1), with a coating amount of 0.03mg / cm². 2 Then, it is cured at 150℃ for 20 minutes to obtain weather-resistant coating 30; the thickness of weather-resistant coating 30 is 30nm, the pencil hardness is 6H, and the light transmittance retention rate is 97.8% after outdoor accelerated aging test (simulating 10 years of outdoor environment);

[0104] (4) Preparation of the encapsulation adapter layer 40:

[0105] 99.5g of ethylene-vinyl acetate, 0.2g of KH-550, and 0.3g of crosslinking agent DCP were mixed to obtain a third slurry; the weight percentage of KH-550 in the third slurry was 0.2wt%; the third slurry was coated on the side of the weather-resistant coating 30 away from the substrate, with a coating amount of 0.05mg / cm². 2Then, it is cured at 140℃ for 15 min to form the encapsulation adapter layer 40, thus obtaining the back contact battery front panel 100. The material of the encapsulation adapter layer 40 is silane-grafted modified ethylene-vinyl acetate, wherein the weight percentage of silane groups is 0.02wt%, the melt index at 190℃ and 2.16kg is 2.0g / 10min, the thickness of the encapsulation adapter layer 40 is 50nm, the surface roughness Ra is 0.05μm, and the peel strength between the encapsulation adapter layer 40 and the EVA encapsulation film is 1.5N / mm.

[0106] Example 3

[0107] A method for preparing a back contact battery front panel 100, comprising:

[0108] (1) Prepare the substrate:

[0109] The photovoltaic-grade low-iron glass mass-produced by Xinyi Glass has a thickness of 3.2 mm, a light transmittance of 93.0% in the wavelength range of 400–1100 nm, a haze of 0.05%, and a surface flatness of 0.05 mm / m. The substrate is obtained by treating it with 200 W plasma for 60 s; the surface tension of the substrate is 50 mN / m.

[0110] (2) Preparation of antireflective layer 10:

[0111] TEOS, TBOT, and the organic solvent PMA were mixed and subjected to a solvothermal reaction at 100°C to obtain a first slurry. The weight ratio of nano-sized silica to nano-sized titanium dioxide in the first slurry was 5:1, and the average particle size was 150 nm. The first slurry was then roll-coated onto one side of the substrate prepared in step (1), with a coating amount of 0.12 mg / cm². 2 Nanoimprinting was performed using a PDMS template, followed by curing at 180°C for 30 minutes to form an antireflection layer 10 with an array of micro-nano uneven structures on one side. Each uneven unit is hemispherical with a radius of 100 nm, and the spacing between two adjacent uneven units is 300 nm. The antireflection layer 10 has a thickness of 120 nm and a reflectivity of 1.1% in the wavelength range of 400–1100 nm.

[0112] (3) Preparation of weather-resistant coating 30:

[0113] 97.0g of fluorocarbon side-chain modified aliphatic polyurethane resin (number average molecular weight of 50000g / mol), 2.0g of UV-P, 1.0g of antioxidant 1010 were mixed with ethyl acetate to obtain a second slurry; wherein the weight percentage of UV-P in the second slurry was 2.0wt% and the weight percentage of antioxidant 1010 was 1.0wt%. The second slurry was then roller-coated onto the other side of the substrate prepared in step (1), with a coating amount of 0.05mg / cm². 2 Then, it is cured at 150℃ for 20 minutes to obtain weather-resistant coating 30; the thickness of weather-resistant coating 30 is 50nm, the pencil hardness is 7H, and the light transmittance retention rate is 99.2% after outdoor accelerated aging test (simulating 10 years of outdoor environment);

[0114] (4) Preparation of the encapsulation adapter layer 40:

[0115] 98.5g of ethylene-vinyl acetate, 0.5g of KH-550, and 1.0g of crosslinking agent DCP were mixed to obtain a third slurry; the weight percentage of KH-550 in the third slurry was 0.5wt%; the third slurry was coated on the side of the weather-resistant coating 30 away from the substrate, with a coating amount of 0.08mg / cm². 2 Then, it is cured at 140℃ for 15 min to form the encapsulation adapter layer 40, thus obtaining the back contact battery front panel 100. The material of the encapsulation adapter layer 40 is silane-grafted modified ethylene-vinyl acetate, wherein the weight percentage of silane groups is 0.5wt%, the melt index at 190℃ and 2.16kg is 3.5g / 10min, the thickness of the encapsulation adapter layer 40 is 80nm, the surface roughness Ra is 0.1μm, and the peel strength between the encapsulation adapter layer 40 and the EVA encapsulation film is 2.0N / mm.

[0116] Example 4

[0117] The difference from Example 1 is that the structure of the PDMS template in step (2) is changed so that the radius of each concave-convex unit in the obtained antireflection layer 10 is 25nm and the spacing between two adjacent concave-convex units is 100nm. The remaining steps are the same as in Example 1.

[0118] Example 5

[0119] The difference from Example 1 is that the structure of the PDMS template in step (2) is changed so that the radius of each concave-convex unit in the obtained antireflection layer 10 is 100 nm and the spacing between two adjacent concave-convex units is 300 nm. The remaining steps are the same as in Example 1.

[0120] Example 6

[0121] The difference from Example 1 is that the structure of the PDMS template in step (2) is changed so that the radius of each concave-convex unit in the obtained antireflection layer 10 is 120 nm and the spacing between two adjacent concave-convex units is 320 nm. The remaining steps are the same as in Example 1.

[0122] Example 7

[0123] The difference from Example 1 is that the ratio of precursors TEOS and TBOT in step (2) is changed so that the weight ratio of nano-sized silica to nano-sized titanium dioxide is 3:1. The remaining steps are the same as in Example 1.

[0124] Example 8

[0125] The difference from Example 1 is that the ratio of precursors TEOS and TBOT in step (2) is changed so that the weight ratio of nano-sized silica to nano-sized titanium dioxide is 5:1. The remaining steps are the same as in Example 1.

[0126] Example 9

[0127] The difference from Example 1 is that the ratio of precursors TEOS and TBOT in step (2) is changed so that the weight ratio of nano-sized silica to nano-sized titanium dioxide is 2.5:1. The remaining steps are the same as in Example 1.

[0128] Example 10

[0129] The difference from Example 1 is that in step (3), the weight ratio of fluorocarbon side-chain modified aliphatic polyurethane resin, UV absorber UV-P and antioxidant 1010 is 98.5:0.5:1.0. The remaining steps are the same as in Example 1.

[0130] Example 11

[0131] The difference from Example 1 is that in step (3), the weight ratio of fluorocarbon side-chain modified aliphatic polyurethane resin, UV absorber UV-P and antioxidant 1010 is 97.7:2.0:0.3. The remaining steps are the same as in Example 1.

[0132] Example 12

[0133] The difference from Example 1 is that in step (3), the weight ratio of fluorocarbon side-chain modified aliphatic polyurethane resin, UV absorber UV-P and antioxidant 1010 is 96.0:3.0:1.0. The remaining steps are the same as in Example 1.

[0134] Example 13

[0135] The difference from Example 1 is that the weight ratio of EVA, KH-550 and crosslinking agent DCP in step (4) is 99.5:0.2:0.3. The remaining steps are the same as in Example 1. The weight percentage of silane groups in the silane-grafted modified ethylene-vinyl acetate is 0.2 wt%.

[0136] Example 14

[0137] The difference from Example 1 is that the weight ratio of EVA, KH-550 and crosslinking agent DCP in step (4) is 98.5:0.5:1.0. The remaining steps are the same as in Example 1. The weight percentage of silane groups in the silane-grafted modified ethylene-vinyl acetate is 0.5 wt%.

[0138] Example 15

[0139] The difference from Example 1 is that the weight ratio of EVA, KH-550 and crosslinking agent DCP in step (4) is 96.0:0.6:1.4. The remaining steps are the same as in Example 1. The weight percentage of silane groups in the silane-grafted modified ethylene-vinyl acetate is 0.6 wt%.

[0140] Comparative Example 1

[0141] The difference from Example 1 is that: a commercially available single silica antireflective layer is used, and its surface does not have an array of micro-nano uneven structures; step (3) preparation of the weather-resistant coating 30 is omitted; in step (4), unmodified EVA is used to directly prepare the EVA coating. The remaining steps are the same as in Example 1. The obtained BC battery front panel includes a silica reflective layer, a glass substrate layer, and an EVA coating stacked sequentially.

[0142] Comparative Example 2

[0143] The difference from Example 1 is that a commercially available single silicon dioxide antireflective layer is used, and its surface does not have an array of micro-nano uneven structures. The remaining steps are the same as in Example 1. The resulting BC battery front panel includes a silicon dioxide reflective layer, a substrate layer 20, a weather-resistant coating 30, and an encapsulation adapter layer 40 stacked sequentially.

[0144] Comparative Example 3

[0145] The difference from Example 1 is that step (3) of preparing the weather-resistant coating 30 is omitted. The remaining steps are the same as in Example 1. The obtained BC battery front panel includes an anti-reflective layer 10, a substrate layer 20, and an encapsulation adapter layer 40 stacked sequentially.

[0146] Comparative Example 4

[0147] The difference from Example 1 is that in step (4), unmodified EVA is used to directly prepare the EVA coating. The remaining steps are the same as in Example 1. The obtained BC battery front panel includes an anti-reflective layer 10, a substrate layer 20, a weather-resistant coating 30, and an EVA coating stacked sequentially.

[0148] Assembly of photovoltaic cell modules:

[0149] The BC cell front panel described in all embodiments and comparative examples of this application is applied to a photovoltaic cell module. A back contact cell front panel 100, a 15μm thick EVA encapsulation film 200 (EVA type: Foster EVA 3010, VA content 30%, melt index 3.0g / 10min, crosslinking degree ≥85%), a back contact cell 300 (Jiangsu Aiko Solar Technology Co., Ltd., model ABC-166, specification 166mm×166mm, rated power 60W), and a 0.3mm thick fluorocarbon composite back sheet as back sheet 400 (Lucky Film FR-150, light transmittance ≤5%, weather resistance conforms to IEC 61215 standard) are sequentially stacked and formed through a lamination process to obtain the following... Figure 2 The photovoltaic cell module shown; wherein, the pressure controlled during the lamination process is 0.12 × 10⁻⁶. 6 The lamination process was carried out at 1.2 bar (Pa) and 145°C for 25 minutes. After lamination, the material was allowed to cool naturally to room temperature (25°C). Subsequently, edge trimming, framing, and junction box installation were performed to complete the fabrication of the photovoltaic cell module.

[0150] The back contact cell 300 structure stack used in the assembly process includes: an N-type monocrystalline silicon substrate, a tunneling oxide layer (SiO2, 1.5 nm thick) and a polycrystalline silicon emitter layer (200 nm thick) sequentially disposed on the front side, and a passivation contact layer (Al2O3 / SiNx stack, 80 nm thick) and a silver electrode disposed on the back side, with a cell thickness of 160 μm.

[0151] The backplate 400 used in the assembly process has a laminated structure of PVDF / Al / PET three-layer composite structure.

[0152] The photovoltaic module assembled above was placed under standard test conditions (AM1.5G, irradiance 1000W / m²). 2 The photoelectric conversion efficiency was tested using a photovoltaic module efficiency tester (model: Newport Oriel IV Test System) at a test temperature of 25℃. The test results are shown in Table 1.

[0153] Performance testing:

[0154] Mass production performance testing was conducted on the BC cell front panels prepared in all the embodiments and comparative examples described above. The testing items and standards all conformed to GB / T 32561-2016 "Glass for Photovoltaic Modules" and IEC 61215-2016 "Design Requirements and Tests for Ground-Mounted Crystalline Silicon Photovoltaic Modules". The test results are shown in Table 1. It should be noted that the light transmittance in Table 1 refers to the light transmittance of the entire BC cell front panel; the surface hardness refers to the surface hardness of the entire BC cell front panel. Since the antireflective layer 10 is located on the outermost layer, its hardness directly determines the overall surface wear resistance and scratch resistance performance of the BC cell front panel (level: 7H > 6H > 5H > 4H).

[0155] Table 1

[0156]

[0157] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0158] Compared to existing antireflective layers 10 that do not include an array of concave and convex structures, the antireflective layer 10 with specific materials and structures in this application can reduce the reflectivity in the 400–1100 nm wavelength range to below 2%, reducing incident light loss and significantly improving the photoelectric conversion efficiency of photovoltaic modules. Using high-transmittance, low-haze glass as the substrate layer 20 increases the effective absorption area of ​​the BC cell for incident sunlight, avoiding energy loss due to light scattering and improving the photoelectric conversion efficiency of the BC cell. Furthermore, the high mechanical strength of glass ensures the structural stability of the photovoltaic module during outdoor installation and transportation, thus meeting the requirements for impact and wind pressure resistance. The weather-resistant coating 30 comprises fluorinated polyurethane, UV absorbers, and antioxidants. Compared to ordinary unmodified polyurethane resin, the fluorinated polyurethane exhibits superior resistance to UV aging, damp heat, salt spray, staining, self-cleaning, and chemical corrosion. The UV absorbers and antioxidants synergistically inhibit UV-induced chain breakage and oxidative degradation, effectively preventing coating cracking and yellowing, thereby enhancing the anti-aging performance of the BC cell front panel. The weather-resistant coating 30 absorbs outdoor UV radiation, delaying the aging of the BC cell front panel and improving the durability and long-term light transmission stability of the photovoltaic module. Compared to traditional EVA, the encapsulation adapter layer 40, formed by in-situ grafting silane groups, improves the interfacial adhesion between the encapsulation adapter layer 40 and the EVA encapsulation film. Furthermore, during subsequent photovoltaic module lamination, the encapsulation adapter layer 40 can fuse with the EVA encapsulation film, reducing lamination bubble rate and thus improving the encapsulation reliability and yield of the photovoltaic module.

[0159] The preparation method provided in this application is fully compatible with existing mainstream BC cell production lines, requiring no additional specialized equipment, and enables efficient and low-cost large-scale manufacturing of high-performance BC cell front panels.

[0160] Comparing Examples 1, 4 to 6, it can be seen that the antireflection layer 10 prepared in Example 4 has a thickness of 80 nm and a reflectivity of 1.3% in the wavelength range of 400-1100 nm, which is comparable to Example 1 (reflectivity 1.2%). The antireflection layer 10 prepared in Example 5 has a thickness of 120 nm and a reflectivity of 1.2% in the wavelength range of 400-1100 nm, which is comparable to Example 1. The antireflection layer 10 prepared in Example 6 has a thickness of 150 nm and a reflectivity of 1.5% in the wavelength range of 400-1100 nm, which is higher than Examples 1, 4 and 5. At the same time, the excessively large concave and convex units lead to a decrease in the surface flatness of the antireflection layer 10 and a decrease in wear resistance. After outdoor accelerated aging test, the light transmittance retention rate is 97.7%, which is slightly worse than Example 1 (98.5%), Example 4 (98.2%) and Example 5 (98.4%).

[0161] Comparing Examples 1, 7 to 9, it can be seen that using the micro-nano uneven structure of the specific size described above in this application is beneficial to enable the incident light to undergo controllable multiple refractions on the nanoscale morphological surface, which is beneficial to reduce the reflectivity in the wavelength range of 400 to 1100 nm, reduce reflection loss, and thus improve the photoelectric conversion efficiency of photovoltaic cell modules.

[0162] Comparing Examples 1, 10, and 12, it can be seen that the weather-resistant coating 30 prepared in Example 10 has a thickness of 40 nm, a pencil hardness of 6H, and a transmittance retention rate of 98.3% after outdoor accelerated aging test (simulating 10 years of outdoor environment), which is comparable to Example 1 (transmittance retention rate of 98.5%). The UV aging resistance and adhesion of the weather-resistant coating 30 are at the same level as those of Example 1, which can meet the weather protection requirements of the front panel of the back contact battery and are not significantly different from Example 1. The weather-resistant coating 30 prepared in Example 11 has a thickness of 40 nm, a pencil hardness of 6H, and a transmittance retention rate of 98.4% after outdoor accelerated aging test, which is comparable to that of Example 1. The coating's resistance to thermo-oxidative aging and wear resistance are comparable to those of Example 1, and it can effectively achieve long-term weather protection. The weather-resistant coating 30 prepared in Example 12 showed slight yellowing and cracking on the surface, and the pencil hardness dropped to 4H. After outdoor accelerated aging test, the light transmittance retention rate was only 94.1%, which was worse than that of Example 1 (98.5%), Example 10 (98.3%), and Example 11 (98.4%). At the same time, the adhesion between the weather-resistant coating 30 and the substrate layer 20 decreased, and it was easy to fall off.

[0163] Comparing Examples 1 and 13 to 15, it can be seen that the encapsulation adapter layer 40 prepared in Example 13 has a thickness of 65 nm, a surface roughness Ra of 0.08 μm, a melt flow index of 2.6 g / 10 min at 190 °C and 2.16 kg, and a peel strength to the EVA encapsulation film of 1.7 N / mm, which is comparable to Example 1. The flexibility and adhesion to the weather-resistant coating 30 of the encapsulation adapter layer 40 are at the same level as in Example 1, which can meet the encapsulation adaptation requirements of the back contact battery front panel. The encapsulation adapter layer 40 prepared in Example 14 has a thickness of 65 nm, a surface roughness Ra of 0.08 μm, a melt flow index of 2.9 g / 10 min at 190 °C and 2.16 kg, and a peel strength to the EVA encapsulation film of 1.9 N / mm, which is comparable to Example 1. The crosslinking degree and aging resistance of the encapsulation adapter layer 40 are comparable to those of Example 1, which can effectively realize the encapsulation adaptation function. The encapsulation adapter layer 40 prepared in Example 15 exhibited excessive cross-linking, decreased flexibility, and surface cracks. Its melt flow index at 190°C and 2.16 kg dropped to 1.5 g / 10 min, and its peel strength from the EVA encapsulation film was only 1.0 N / mm, significantly worse than Examples 1, 13, and 14. Simultaneously, the adhesion between the encapsulation adapter layer 40 and the weather-resistant coating 30 was insufficient, easily leading to delamination. Performance test results showed that the photovoltaic cell modules prepared in Examples 1, 13 to 15 all had photoelectric conversion efficiencies between 23.5% and 24.2%, with Example 1 having the highest efficiency (24.2%). Examples 13 and 14 had photoelectric conversion efficiencies comparable to Example 1, while Example 15 had a photoelectric conversion efficiency of 23.5% (slightly lower but still better than the comparative example). The module prepared in Comparative Example 4 had a photoelectric conversion efficiency of only 21.9%, significantly lower than all other examples. This indicates that the design of the encapsulation adapter layer 40 provided in this application can effectively improve the photoelectric conversion efficiency of photovoltaic cell modules while ensuring long-term stability.

[0164] Comparing Example 1 and Comparative Example 4, it can be seen that the peel strength between the EVA coating and the weather-resistant coating 30 prepared in Comparative Example 4 is only 0.8 N / mm, which is much lower than 1.8 N / mm in Example 1. After 6 months of outdoor accelerated aging test, the EVA coating showed yellowing and powdering, and the light transmittance dropped to 85%. After being assembled into a photovoltaic cell module, the photoelectric conversion efficiency was significantly reduced, which could not meet the requirements for long-term stable use of photovoltaic modules.

[0165] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those described herein.

[0166] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A back-contact battery front panel, characterized in that, The back contact battery front panel (100) includes an antireflection layer (10), a substrate layer (20), a weather-resistant coating (30), and an encapsulation adapter layer (40) stacked sequentially. The antireflection layer (10) is made of nanoscale inorganic oxides. The antireflection layer (10) has an array of concave and convex structures on the side of its surface away from the substrate layer (20). The antireflection layer (10) has a reflectivity of ≤2% in the wavelength range of 400-1100nm. The substrate layer (20) is made of glass. The substrate layer (20) has a light transmittance of ≥92% and a haze of ≤0.1%. The weather-resistant coating (30) is made of fluorinated polyurethane, ultraviolet absorbers, and antioxidants. The encapsulation adapter layer (40) is made of silane-grafted modified ethylene-vinyl acetate.

2. The back contact battery front panel according to claim 1, characterized in that, In the arrayed concave-convex structure, each concave-convex unit is spherical or hemispherical, with a radius of 25–100 nm and a spacing of 100–300 nm between adjacent units; and / or, The antireflective layer (10) is made of a mixture of nano-silica and nano-titanium dioxide, preferably with a weight ratio of nano-silica to nano-titanium dioxide of (3-5):1; and / or, The thickness of the antireflective layer (10) is 80-120 nm.

3. The back contact battery front panel according to claim 1 or 2, characterized in that, By weight percentage, the weather-resistant coating (30) comprises 97.0–99.2 wt% of the fluorinated polyurethane, 0.5–2.0 wt% of the UV absorber, and 0.3–1.0 wt% of the antioxidant; and / or, Preferably, the fluorinated polyurethane is selected from perfluoropolyether modified polyurethane and / or fluorocarbon side-chain modified polyurethane; Preferably, the ultraviolet absorber is selected from benzotriazole ultraviolet absorbers; more preferably, it is one or more of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole and 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole; Preferably, the antioxidant is selected from hindered phenolic antioxidants; more preferably, it is one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)triazine and 2,6-di-tert-butyl-4-ethylphenol.

4. The back-contact battery front panel according to any one of claims 1 to 3, characterized in that, The thickness of the weather-resistant coating (30) is 30–50 nm; and / or, The pencil hardness of the weather-resistant coating (30) is ≥6H.

5. The back-contact battery front panel according to any one of claims 1 to 4, characterized in that, The silane-grafted modified ethylene-vinyl acetate has a silane group content of 0.2–0.5 wt% by weight; and / or, The silane-grafted modified ethylene-vinyl acetate has a melt index of 2.0–3.5 g / 10 min at 190 °C and 2.16 kg; and / or, The thickness of the encapsulation adapter layer (40) is 50–80 nm; and / or, The surface roughness Ra of the encapsulation adapter layer (40) is 0.05~0.1μm, the peel strength between the encapsulation adapter layer (40) and the EVA encapsulation film is ≥1.5N / mm, and the interfacial tension difference between the encapsulation adapter layer (40) and the EVA encapsulation film is ≤5mN / m.

6. The back-contact battery front panel according to any one of claims 1 to 5, characterized in that, The surface flatness of the substrate layer (20) is ≤0.1mm / m; and / or, The thickness of the substrate layer (20) is 2.0–3.2 mm; and / or, The thickness of the back contact battery front panel (100) is 2.16 to 3.43 mm.

7. A method for preparing a back-contact battery front panel according to any one of claims 1 to 6, characterized in that, The method for preparing the back contact battery front panel (100) includes: Step S1: A first slurry containing nano-sized inorganic oxides is prepared by sol-gel method; the first slurry is coated on one side surface of the substrate, and then nanoimprinting is performed. After the first curing, a substrate with an anti-reflection layer (10) is obtained on the surface; the material of the substrate is selected from glass. Step S2: Fluorinated polyurethane, UV absorber, antioxidant and solvent are mixed to obtain a second slurry; the second slurry is coated on the other side of the substrate and after a second curing, a weather-resistant coating (30) is obtained. Step S3: Mix ethylene-vinyl acetate, silane coupling agent, and crosslinking agent to obtain a third slurry; coat the third slurry onto the surface of the weather-resistant coating (30) away from the substrate, and then perform a third curing to form an encapsulation adapter layer (40), thus obtaining a back-contact battery front panel (100); or, Ethylene-vinyl acetate, silane coupling agent, crosslinking agent and initiator are mixed to obtain a fourth slurry; the fourth slurry is coated on the side of the weather-resistant coating (30) away from the substrate, and then a fourth curing is performed to form an encapsulation adapter layer (40) to obtain a back contact battery front panel (100).

8. The method for preparing the front panel of the back contact battery according to claim 7, characterized in that, The preparation method of the first slurry includes: mixing a precursor with an organic solvent and carrying out a solvothermal reaction to obtain the first slurry; preferably, the precursor is selected from a mixture of tetraethyl orthosilicate and tetrabutyl titanate, or a mixture of tetraethyl orthosilicate and tetraisopropyl titanate; preferably, the average particle size of the nano-sized inorganic oxide is 50-200 nm; preferably, the coating amount of the first slurry is 0.08-0.12 mg / cm³. 2 The nanoimprinting is preferably performed using a polydimethylsiloxane template; the first curing temperature is preferably 170–190°C, and the time is preferably 25–35 min; and / or, The weight ratio of the fluorinated polyurethane, the UV absorber, and the antioxidant is (97.0–99.2):(0.5–2.0):(0.3–1.0); preferably, the coating amount of the second slurry is 0.03–0.05 mg / cm³. 2 The preferred second curing temperature is 140–160°C, and the time is 15–25 min; and / or, Based on the weight percentage of the third slurry, the third slurry comprises 97.0–99.3 wt% of the ethylene-vinyl acetate, 0.2–0.5 wt% of the silane coupling agent, 0.2–1.0 wt% of the crosslinking agent, and the balance being an optional first auxiliary agent; or, based on the weight percentage of the fourth slurry, the fourth slurry comprises 96.5–99.0 wt% of the ethylene-vinyl acetate, 0.2–0.5 wt% of the silane coupling agent, 0.2–1.0 wt% of the crosslinking agent, 0.3–1.5 wt% of the initiator, and the balance being an optional second auxiliary agent. Additives; preferably, the first and second additives are each independently selected from one or more of leveling agents, defoamers, and antistatic agents; preferably, the silane coupling agent is selected from one or more of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane; preferably, the crosslinking agent is selected from peroxide crosslinking agents and / or isocyanate crosslinking agents; preferably, the initiator is selected from one or more of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, tert-butyl peroxide, and azobisisobutyronitrile; and / or, The coating amount of the third slurry is 0.05–0.08 mg / cm³. 2 The preferred third curing temperature is 130–150°C, and the time is 10–20 min; or, the coating amount of the fourth slurry is 0.05–0.08 mg / cm³. 2 The preferred curing temperature for the fourth stage is 130–150°C, and the curing time is 10–20 min.

9. The method for preparing the front panel of the back contact battery according to claim 7, characterized in that, The preparation method of the back contact battery front panel (100) further includes: plasma treatment of the glass substrate to obtain the substrate; preferably, the power of the plasma treatment is 100-200W and the time is 30-60s; preferably, the surface tension of the substrate is ≥45mN / m.

10. A photovoltaic cell module, comprising a front panel, an encapsulating film (200), a back contact cell (300), and a back panel (400) stacked sequentially, characterized in that, The front panel is selected from the back contact battery front panel (100) according to any one of claims 1 to 6. The front side of the back contact battery cell (300) is close to the encapsulation film (200), the back side of the back contact battery cell (300) is close to the back panel (400), and positive and negative grid lines are provided on the back side of the back contact battery cell (300).

Images