High-performance perovskite heterojunction high-efficiency packaging special-purpose photovoltaic PVB film and preparation method thereof

Abstract

The invention provides a special photovoltaic PVB (Polyvinyl Butyral) film for efficiently packaging a high-performance perovskite heterojunction and a preparation method of the special photovoltaic PVB film. The PVB film is prepared by adopting poly (vinyl butyral) resin, a composite plasticizer, a composite bonding enhancer, an efficient ultraviolet screening agent, a hydrolysis-resistant stabilizer and a dispersing agent as raw materials through the steps of premixing, dispersion treatment, melt extrusion and filtration, tape casting cooling, calendering finishing and the like. The prepared PVB film has the advantages of excellent water vapor barrier property, high interface bonding strength, low plasticizer migration rate, good ultraviolet shielding and weather resistance, strong adaptability and the like.

Description

Technical Field

[0001] This invention belongs to the field of film technology for solar cell encapsulation, specifically relating to a high-performance perovskite heterojunction photovoltaic PVB film for high-efficiency encapsulation and its preparation method. Background Technology

[0002] Perovskite heterojunction solar cells have become a research hotspot in the photovoltaic field due to their high photoelectric conversion efficiency and low manufacturing cost. However, the core layer is extremely sensitive to water, oxygen, and high temperatures, and the performance of the encapsulation material directly determines the long-term service life of the cell. Currently, commonly used PVB films for photovoltaic encapsulation have several shortcomings: firstly, their water vapor barrier performance is insufficient, with a water vapor permeability > 5 g / (m²) under 40 ℃ / 90 %RH conditions. 2 First, the perovskite layer is prone to hydrolysis and degradation (24h); second, the adhesion strength between the perovskite layer and the battery electrode layer (such as ITO, silver grid lines) is low, and interlayer delamination is likely to occur during long-term service; third, plasticizers are prone to migrate to the heterojunction interface, destroying the charge carrier transport channel and causing the battery efficiency to decrease; fourth, the ultraviolet shielding performance is limited and cannot effectively protect the perovskite layer from photo-induced degradation.

[0003] Regarding the preparation of PVB films, CN118027854A discloses a light-converting PVB film for photovoltaic encapsulation, which is prepared from polyvinyl butyral resin, plasticizer, acrylate, ultraviolet absorber, antioxidant, silane coupling agent, and light-converting agent. The prepared PVB film has good resistance to ultraviolet aging, maintaining high light transmittance even after long-term ultraviolet irradiation, is not prone to yellowing, and has good performance. CN103044826A discloses a PVB film for solar photovoltaic modules, whose components are: polyvinyl butyral resin, plasticizer, antioxidant, ultraviolet absorber, and weather-resistant additive, wherein the weather-resistant additive is nano-silica or nano-titanium dioxide. The prepared PVB film has good adhesion to glass, good weather resistance, and good insulation. Solar photovoltaic modules made with it show no defects or delamination after long-term storage in high-temperature and high-humidity environments, and have high light transmittance. CN105599328A discloses a method for manufacturing PVB film for solar photovoltaic power generation equipment. The method involves weighing and mixing PVB resin, calcium carbonate, PE antistatic agent, plasticizer, surfactant, dispersant, coupling agent, antioxidant, and ultraviolet absorber. The mixture is then preheated, melted, and conveyed to a mold for natural molding under preset time, temperature, and pressure to obtain a semi-finished product. The semi-finished product is then fed into a roller by a traction mechanism and rolled into a cylindrical shape. During the traction process, it is cooled, flattened, and cut according to the required width. After inspection and packaging, the PVB film is obtained. The resulting PVB film material has good surface smoothness and gloss, high longitudinal and transverse strength, good longitudinal and transverse ductility, and can maintain permanent ultraviolet protection without reducing the material's light transmittance. However, none of the above-mentioned PVB films are specifically designed for perovskite heterojunction solar cells, and they do not solve problems such as water vapor barrier. Other related studies have attempted to add inorganic nanoparticles to improve the barrier properties of films (see reference: Yin Feixiang, KAPAMBWE Bwalya, Lin Zhiqian, et al. Research progress on improving the gas barrier properties of biodegradable films based on nanomaterials [J]. Journal of Composite Materials, 2024, 41(10): 5270-5282), but this easily leads to a decrease in film transmittance; using multilayer composite structures increases the preparation cost and process complexity, and none of these studies have fully solved the above problems. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a high-performance perovskite heterojunction photovoltaic PVB film for efficient encapsulation and its preparation method. The PVB film is prepared using poly(vinyl butyral) resin, composite plasticizer, composite adhesive reinforcing agent, high-efficiency UV shielding agent, hydrolysis-resistant stabilizer, and dispersant as raw materials. The process involves premixing, dispersion treatment, melt extrusion and filtration, casting and cooling, and calendering finishing. The prepared PVB film exhibits advantages such as excellent water vapor barrier properties, high interfacial adhesion strength, low plasticizer migration, good UV shielding and weather resistance, and strong adaptability.

[0005] The technical solution of the present invention is: a high-performance perovskite heterojunction high-efficiency encapsulation photovoltaic PVB film, characterized in that it is prepared from the following raw materials in parts by weight: poly(vinyl butyral) resin: 80-100 parts, composite plasticizer: 30-45 parts, composite adhesive reinforcing agent: 2-5 parts, high-efficiency ultraviolet shielding agent: 1-3 parts, hydrolysis resistant stabilizer: 0.5-1.5 parts, dispersant: 0.3-0.8 parts.

[0006] Preferably, the poly(vinyl butyral) resin has an acetal degree of 70-78 wt%, a hydroxyl content of 12-18 wt%, and an acetoxy content ≤ 3 wt%. The preparation method is as follows: polyvinyl alcohol (degree of polymerization 1700-2000) and n-butyral are reacted at 30-40 ℃ for 4-6 h under the action of 1-2 mol / L hydrochloric acid catalyst, neutralized to pH = 6.5-7.5 with 0.5-1 mol / L sodium hydroxide solution, and washed and dried to a moisture content ≤ 0.8 wt%.

[0007] The composite plasticizer is prepared by compounding dipropylene glycol dibenzoate (high barrier plasticizer) and 2,2,4-trimethyl-1,3-pentanediol dibenzoate (low migration plasticizer) in a mass ratio of 1:1.5-2.5.

[0008] The composite adhesive reinforcing agent is prepared by compounding γ-aminopropyltriethoxysilane (aminosilane coupling agent) and epoxy-modified graphene at a mass ratio of 3-5:1; the epoxy-modified graphene has an epoxy group grafting rate of 8-12% and a sheet thickness ≤ 5 nm. The preparation method of the epoxy-modified graphene is as follows: graphene (purity ≥ 99%) is dispersed in N,N-dimethylformamide, epichlorohydrin and triethylamine (molar ratio 1:0.8-1) are added, the reaction is carried out at 60-70 ℃ for 8-10 h, and then filtered, washed and vacuum dried.

[0009] Preferably, the high-efficiency UV shielding agent is cerium-doped zinc oxide nanoparticles with a particle size of 20-50 nm and a cerium doping amount of 3-5 at%. The preparation method of cerium-doped zinc oxide nanoparticles is as follows: zinc nitrate and cerium nitrate (molar ratio 95-97:3-5) are dissolved in deionized water, citric acid (molar ratio to total metal ions 1:1) is added, and the mixture is stirred at 80-90 °C to form a gel, followed by calcination at 500-550 °C for 2-3 h.

[0010] Preferably, the hydrolysis-resistant stabilizer is caprolactam copper salt, more preferably bis(ε-caprolactam)copper(II) salt (C 12 H 22 CuN2O2).

[0011] Preferably, the dispersant is tristearate.

[0012] Its preparation method is as follows: 1) Premixing: Poly(vinyl butyral) resin, composite plasticizer and hydrolysis stabilizer are added to a high-speed mixer and stirred to allow the composite plasticizer to fully penetrate the resin particles, so as to obtain a uniform and stable premix. 2) Dispersion treatment: Add composite binder, high-efficiency UV shielding agent and dispersant to the premix, and then transfer it to a planetary ball mill for ball milling to obtain a uniformly dispersed mixture; 3) Melt extrusion and filtration: The mixture is added to the hopper of a twin-screw extruder for melt extrusion; the extruder temperature is set in sections: Zone 1 160-165 ℃, Zone 2 170-175 ℃, Zone 3 175-180 ℃, and the die head 178-180 ℃, with a screw speed of 30-50 r / min; after filtering to remove impurities and undispersed particles, the molten material is extruded through a T-shaped flat die, with the die head temperature controlled at 175-180 ℃; 4) Casting and cooling: The extruded melt preform is evenly adhered to the surface of the casting roller. The casting roller adopts three-stage temperature control: the first stage is 80-85℃, the second stage is 70-75℃, and the third stage is 60-65℃. 5) Calendering and finishing: After cooling, the film material enters a two-roll calender. The temperature of the calender rolls is 80-90 ℃. The film material is calendered to the target thickness of 0.38-0.76 mm by adjusting the pressure between the rolls (0.3-0.5 MPa). 6) Then, after thickness measurement and edge trimming, vacuum drying, and winding and packaging, PVB film is obtained.

[0013] Furthermore, in step 1), the mixing temperature is 80-90 ℃, the stirring speed is 800-1000 r / min, and the stirring is continued for 30-45 min.

[0014] Furthermore, in step 2), the nanoparticles are ball-milled at a speed of 200-300 r / min for 1-2 h, with the machine stopped every 30 min to take samples and observe the dispersion state, to ensure that the nanoparticles do not agglomerate (particle size ≤50 nm).

[0015] Furthermore, in step 4), the temperature fluctuation of the roller surface is controlled to be ≤2℃ by circulating cooling water; the film blank is cooled and shaped on the casting roller for 3-5 seconds to ensure that the film material is initially cured and no internal stress is generated.

[0016] The compounding principle of the composite plasticizer of this invention: 1. Complementary structure: Both are benzoic acid esters, and the ester group forms hydrogen bonds with the hydroxyl group of PVB resin to ensure compatibility; the linear structure of dipropylene glycol dibenzoate optimizes the regularity of the molecular chain, while the branched structure of 2,2,4-trimethyl-1,3-pentanediol dibenzoate fills the gaps, synergistically improving the compactness of the membrane structure.

[0017] 2. Synergistic effect: Dipropylene glycol dibenzoate enhances water vapor barrier through polar barrier and molecular entanglement, while 2,2,4-trimethyl-1,3-pentanediol dibenzoate inhibits migration through steric hindrance and strong interaction, balancing the two core functions in a ratio of 1:1.5-2.5.

[0018] 3. Process environment compatibility: The melting point and boiling point of both are compatible with the PVB film melt extrusion process (160-180℃), and their hydrolysis resistance and UV aging resistance are matched with the service requirements of the film material, and they are also compatible with the functions of other additives.

[0019] The chemical bonding principle between the composite adhesive reinforcing agent and the electrode layer in this invention: 1. Silane coupling agent bridging: The amino group of γ-aminopropyltriethoxysilane forms NO covalent bonds or coordinate bonds with the hydroxyl / oxidation groups on the electrode layer surface. The silanol groups generated by ethoxy hydrolysis form Si-OC covalent bonds with the hydroxyl groups of PVB resin, thereby achieving chemical connection between the PVB film and the electrode layer.

[0020] 2. Epoxy-modified graphene crosslinking: The epoxy groups on the graphene surface undergo a ring-opening reaction with the amino groups of the silane coupling agent to form CN bonds, and at the same time form COC bonds with the hydroxyl groups of PVB resin, constructing a three-dimensional crosslinking network and strengthening the interfacial bonding.

[0021] 3. Synergistic anchoring effect: Silane coupling agent provides "point" chemical bonding, and graphene sheets form "surface" physical anchoring through high specific surface area, filling interface voids, dispersing interlayer stress, and improving adhesion stability.

[0022] The ultraviolet shielding mechanism of cerium-doped zinc oxide nanoparticles in this invention is as follows: 1. Broad spectrum absorption: ZnO intrinsically absorbs ≤387nm ultraviolet light. Ce doping introduces impurity energy levels, extending the absorption range to 400nm. Combined with Ce ion 4f electron transition absorption, it achieves full ultraviolet region (280-400nm) coverage.

[0023] 2. Harmless energy dissipation: After absorbing ultraviolet light, electrons and holes dissipate as heat energy through non-radiative recombination, and Ce... 3+ It can suppress the photocatalytic activity of ZnO and prevent free radicals from damaging the membrane material.

[0024] 3. Nanoscale scattering synergy: The 20-50nm particle size matches the ultraviolet light wavelength, and the barrier is enhanced through Mie scattering; because the particle size is smaller than the visible light wavelength, it has minimal impact on the transmittance of visible light in the 400-800nm ​​range.

[0025] Compared with existing technologies, the PVB membrane prepared by this invention has the following advantages: 1) Excellent water vapor barrier performance: water vapor permeability ≤ 1.5 g / (m²) under 40 ℃ / 90% RH conditions. 2 1) Effectively inhibits hydrolysis of the perovskite layer (24h); 2) High interfacial adhesion strength: peel strength from the electrode layer ≥ 45 N / cm, significantly better than traditional PVB film (≤ 30 N / cm), avoiding interlayer peeling; 3) Low plasticizer migration rate: migration amount ≤ 0.5 wt% after aging at 85 ℃ / 85% RH for 1000 h, protecting carrier transport at the heterojunction interface; 4) Good UV shielding and weather resistance: UV shielding rate ≥ 95%, yellowness index ≤ 1.2 after UV aging for 1000 h, transmittance (400-800 nm) ≥ 90%; 5) Strong adaptability: thermal expansion coefficient matches the battery module, after encapsulation, the photoelectric conversion efficiency decay rate ≤ 5% after aging at 85℃ / 85% RH for 1000 h, better than traditional PVB film encapsulated batteries (decrease rate ≥ 15%).

[0026] The technical effects of this invention are: 1. A composite plasticizer with a specific ratio is used in conjunction with epoxy-modified graphene to achieve high water vapor barrier and low plasticizer migration. 2. Composite adhesive reinforcement design: Aminosilane coupling agent is compounded with epoxy modified graphene to form chemical bonds with the electrode layer, thereby improving the interfacial adhesion strength; 3. High-efficiency UV shielding system: Cerium-doped zinc oxide nanoparticles are selected to balance UV shielding and light transmission performance, and anti-hydrolysis stabilizers are added to improve weather resistance; 4. Optimized preparation process: Through premixing, planetary ball milling dispersion, segmented temperature-controlled melt extrusion and calendering drying, the uniform dispersion of raw materials and the stability of membrane performance are ensured. 5. Precise raw material parameter control: Clearly define the key performance parameters of poly(vinyl butyral) resin, epoxy-modified graphene, and cerium-doped zinc oxide nanoparticles to ensure product consistency and reliability. Detailed Implementation

[0027] The effects are illustrated below with reference to specific examples.

[0028] Example 1: Raw material formulation: 85 parts of poly(vinyl butyral) resin (acetal degree 75%, hydroxyl 15 wt%, acetoxy 1.6 wt%), 35 parts of composite plasticizer (14 parts of dipropylene glycol dibenzoate + 21 parts of 2,2,4-trimethyl-1,3-pentanediol dibenzoate), 3 parts of composite adhesive reinforcing agent (2.25 parts of γ-aminopropyltriethoxysilane + 0.75 parts of epoxy-modified graphene, epoxy grafting rate 10%), 2 parts of high-efficiency ultraviolet shielding agent (cerium-doped zinc oxide nanoparticles, particle size 20 nm, cerium doping amount 5 at%), 1 part of hydrolysis resistant stabilizer (bis(ε-caprolactam)copper(II) salt), and 0.5 parts of dispersant (glyceryl tristearate).

[0029] Preparation method: The preparation method of PVB membrane specifically includes the following steps: 1) Premixing: Add poly(vinyl butyral) resin, composite plasticizer, and hydrolysis stabilizer to a high-speed mixer, set the mixing temperature to 85℃ and the stirring speed to 800-1000 r / min, and continue stirring for 45 min to allow the composite plasticizer to fully penetrate the resin particles, resulting in a uniform and stable premix. Before discharge, the moisture content of the premix should be ≤0.8wt%. 2) Dispersion treatment: Add composite binder, high-efficiency UV shielding agent and dispersant to the premix, transfer to planetary ball mill, select zirconia balls (ball-to-material ratio 5:1), ball mill at 300 r / min for 1.5 h, stop the machine every 30 min to take samples to observe the dispersion state, ensure that the nanoparticles do not agglomerate (particle size ≤50 nm), and finally obtain a uniformly dispersed mixture; 3) Melt extrusion and filtration: The mixture is added to the hopper of a twin-screw extruder, which is protected by nitrogen (flow rate 5-10 L / min) to prevent moisture absorption. The extruder temperature is set in sections: Zone 1 165 ℃, Zone 2 172 ℃, Zone 3 178 ℃, and the die head 178-180 ℃. The screw speed is 40 r / min, and the material residence time in the barrel is 8-12 min. After the molten material is filtered through a 120-mesh metal filter to remove impurities and undispersed particles, it is extruded through a T-shaped flat die. The die head temperature is controlled at 175-180 ℃, and the die lip gap is preset to 0.4-0.8 mm according to the target thickness. 4) Casting and Cooling: The extruded molten film preform is evenly bonded to the surface of the casting roller. The casting roller adopts three-stage temperature control: the first stage is 80-85℃, the second stage is 70-75℃, and the third stage is 60-65℃. The temperature fluctuation of the roller surface is controlled to ≤2℃ by circulating cooling water. The film preform is cooled and shaped on the casting roller for 3-5 seconds to ensure that the film material is initially cured and no internal stress is generated.

[0030] 5) Calendering and finishing: After cooling, the film material enters the twin-roll calender. The calender roll temperature is 85℃ and the roll speed is 3-5 m / min. The film material is calendered to the target thickness of 0.5 mm by adjusting the inter-roll pressure (0.3-0.5 MPa). The uniformity of film material thickness is monitored in real time during the calendering process, and the deviation is controlled within ±0.02 mm.

[0031] 6) Thickness measurement and edge trimming: The thickness of the calendered membrane is continuously measured by an online laser thickness gauge (measurement accuracy ±0.005 mm), and the calendering parameters are dynamically adjusted according to the measurement data. Then, the rough edges on both sides of the membrane are removed by an edge trimming machine (5-10 mm width removed on each side) to ensure that the width of the membrane is consistent (standard width 1.2-1.5 m, which can be adjusted as needed).

[0032] 7) Vacuum drying: The cut membrane material is sent into a vacuum drying oven, the temperature is set to 45 ℃ and the vacuum degree is -0.08~-0.09 MPa, and the drying time is 8-12 h. During this period, the temperature and humidity inside the oven are recorded every 2 h to ensure that the final moisture content of the membrane material is ≤0.5wt% and to remove residual volatiles.

[0033] 8) Rewinding and Packaging: After drying, the film material is guided to the rewinding machine via a tension control device (tension set at 50-80 N). The rewinding speed is synchronized with the calendering speed (3-5 m / min), using a surface winding method. The rewinding diameter is controlled at 300-500 mm, and the core is made of paper or plastic (76 mm in diameter). After rewinding, the film is sealed with moisture-proof packaging film, labeled with product label (indicating model, thickness, production date, and batch number), and stored in the warehouse (storage environment: temperature 20-25 ℃, humidity ≤60% RH). Product performance is shown in Table 1.

[0034] Example 2: Raw material preparation (parts by weight): 90 parts of poly(vinyl butyral) resin (acetal degree 72%, hydroxyl 16 wt%, acetoxy 1.7 wt%), 40 parts of composite plasticizer (16 parts of dipropylene glycol dibenzoate + 24 parts of 2,2,4-trimethyl-1,3-pentanediol dibenzoate), 4 parts of composite adhesive reinforcing agent (3 parts of γ-aminopropyltriethoxysilane + 1 part of epoxy-modified graphene, epoxy grafting rate 12%), 2.5 parts of high-efficiency ultraviolet shielding agent (cerium-doped zinc oxide nanoparticles, particle size 50 nm, cerium doping amount 3 at%), 1.2 parts of hydrolysis resistant stabilizer (bis(ε-caprolactam)copper(II) salt), and 0.6 parts of dispersant (glyceryl tristearate).

[0035] Preparation method: The calendering thickness is 0.6 mm, and the rest is the same as in Example 1. The product performance is shown in Table 1.

[0036] Example 3: Raw material preparation (parts by weight): 80 parts of poly(vinyl butyral) resin (acetal degree 70%, hydroxyl 18 wt%, acetoxy 1.5 wt%), 30 parts of composite plasticizer (12 parts of dipropylene glycol dibenzoate + 18 parts of 2,2,4-trimethyl-1,3-pentanediol dibenzoate), 2 parts of composite adhesive reinforcing agent (1.5 parts of γ-aminopropyltriethoxysilane + 0.5 parts of epoxy-modified graphene, epoxy grafting rate 12%), 1 part of high-efficiency ultraviolet shielding agent (cerium-doped zinc oxide nanoparticles, particle size 20 nm, cerium doping amount 5 at%), 0.5 parts of hydrolysis resistant stabilizer (bis(ε-caprolactam)copper(II) salt), and 0.3 parts of dispersant (glyceryl tristearate).

[0037] Preparation method: 1) Premixing: Stir at 80 ℃ for 30 min, the rest is the same as in Example 1; 2) Dispersion treatment: ball milling at 200 r / min for 1 h using a planetary ball mill, the rest is the same as in Example 1; 3) Melt extrusion: Twin-screw extruder, zone 1 160 ℃, zone 2 170 ℃, zone 3 175 ℃, screw speed 30 r / min, T-die extrusion, the rest is the same as in Example 1; 4) Calender the film to a thickness of 0.38 mm at 80 °C, then vacuum dry it at 40 °C for 8 h to obtain a PVB film. The rest of the process is the same as in Example 1. The product performance is shown in Table 1.

[0038] Example 4: Raw material preparation (parts by weight): 100 parts of poly(vinyl butyral) resin (acetal degree 78%, hydroxyl 12 wt%, acetoxy 1.8 wt%), 45 parts of composite plasticizer (18 parts of dipropylene glycol dibenzoate + 27 parts of 2,2,4-trimethyl-1,3-pentanediol dibenzoate), 5 parts of composite adhesive reinforcing agent (4 parts of γ-aminopropyltriethoxysilane + 1 part of epoxy-modified graphene, epoxy grafting rate 8%), 3 parts of high-efficiency ultraviolet shielding agent (cerium-doped zinc oxide nanoparticles, particle size 50 nm, cerium doping amount 3 at%), 1.5 parts of hydrolysis resistant stabilizer (bis(ε-caprolactam)copper(II) salt), and 0.8 parts of dispersant (glyceryl tristearate).

[0039] Preparation process: 1) Premixing: Stir at 90 °C for 45 min, the rest is the same as in Example 1; 2) Dispersion treatment: ball milling at 300 r / min for 2 h using a planetary ball mill, the rest is the same as in Example 1; 3) Melt extrusion: Twin-screw extruder, zone 1 165 ℃, zone 2 175 ℃, zone 3 180 ℃, screw speed 50 r / min, T-die extrusion, the rest is the same as in Example 1; 4) Calender the film to a thickness of 0.76 mm at 90 °C, then vacuum dry it at 50 °C for 12 h to obtain a PVB film. The rest of the process is the same as in Example 1. The product performance is shown in Table 1.

[0040] The product performance indicators of Examples 1-4 are shown in Table 1. Specifically, water vapor transmission rate (40℃ / 90%RH) was determined using GB / T26253-2010 "Determination of Water Vapor Transmission Rate of Plastic Films and Sheets - Infrared Detector Method"; peel strength was determined using GB / T 2790-1995 "Test Method for 180° Peel Strength of Adhesives - Flexible Materials vs. Rigid Materials"; ultraviolet shielding rate (280-400nm) was determined using GB / T 2410-2008 "Determination of Light Transmittance and Haze of Transparent Plastics"; plasticizer migration was determined using GB / T 33372-2016 "Determination of Volatile Organic Compounds (VOCs) and Aldehydes Released from Adhesives," using gas chromatography-mass spectrometry (GC-MS) to determine the amount of plasticizer that migrated to the simulated medium after aging; yellowness index was determined using GB / T... The yellowing resistance of wood coatings was tested according to GB / T 23983-2009 "Determination of Yellowing Resistance of Wood Coatings" (which uses the yellowing resistance test principle to evaluate the yellowing change of PVB film after UV aging). The transmittance (400-800nm) was tested according to GB / T 2410-2008 "Determination of Transmittance and Haze of Transparent Plastics". The photoelectric conversion efficiency attenuation rate was tested according to IEC 61215:2021 "Design Requirements and Test Methods for Crystalline Silicon Photovoltaic Modules for Ground Use". The photoelectric conversion efficiency of the cells before and after aging was measured by a photovoltaic module power tester, and the attenuation rate was calculated.

[0041] Table 1 Product Performance Indicators

[0042] Note: The traditional PVB film is Eastman Saflex. TM DG4100.

[0043] As shown in Table 1, compared with traditional PVB films, the PVB film prepared in this invention has advantages such as low water vapor transmission rate, high peel strength, high UV shielding rate and light transmittance, low plasticizer migration and yellowness index, and low photoelectric conversion efficiency attenuation rate. Its water vapor transmission rate is ≤ 1.5 g / (m²) under 40 ℃ / 90% RH conditions. 2 After 24 hours, the peel strength from the electrode layer is ≥ 45 N / cm, the plasticizer migration is ≤ 0.5 wt%, the UV shielding rate is ≥ 95%, the yellowness index after 1000 hours of UV aging is ≤ 1.2, the transmittance (400-800 nm) is ≥ 90%, and the photoelectric conversion efficiency decay rate is ≤ 5%.

Claims

1. A high-performance perovskite heterojunction high-efficiency encapsulation photovoltaic PVB film, characterized in that, It is prepared from the following raw materials in parts by weight: poly(vinyl butyral) resin: 80-100 parts, composite plasticizer: 30-45 parts, composite adhesive reinforcing agent: 2-5 parts, high-efficiency ultraviolet shielding agent: 1-3 parts, hydrolysis resistant stabilizer: 0.5-1.5 parts, dispersant: 0.3-0.8 parts; The composite plasticizer is prepared by compounding dipropylene glycol dibenzoate and 2,2,4-trimethyl-1,3-pentanediol dibenzoate in a mass ratio of 1:1.5-2.

5. The composite adhesive reinforcing agent is prepared by compounding γ-aminopropyltriethoxysilane and epoxy-modified graphene in a mass ratio of 3-5:

1. The high-efficiency ultraviolet shielding agent is cerium-doped zinc oxide nanoparticles.

2. The high-performance perovskite heterojunction high-efficiency encapsulation photovoltaic PVB film as described in claim 1, characterized in that, The poly(vinyl butyral) resin has an acetal degree of 70-78 wt%, a hydroxyl content of 12-18 wt%, and an acetoxy content of ≤ 3 wt%.

3. The high-performance perovskite heterojunction high-efficiency encapsulation photovoltaic PVB film as described in claim 1, characterized in that, The epoxy-modified graphene has an epoxy group grafting rate of 8-12% and a sheet thickness of ≤ 5 nm.

4. The high-performance perovskite heterojunction high-efficiency encapsulation photovoltaic PVB film as described in claim 1, characterized in that, The cerium-doped zinc oxide nanoparticles have a particle size of 20-50 nm and a cerium doping amount of 3-5 at.

5. The high-performance perovskite heterojunction high-efficiency encapsulation photovoltaic PVB film as described in claim 1, characterized in that, The hydrolysis-resistant stabilizer is caprolactam copper salt.

6. The high-performance perovskite heterojunction high-efficiency encapsulation photovoltaic PVB film as described in claim 1, characterized in that, The dispersant is tristearate.

7. The method for preparing a high-performance perovskite heterojunction high-efficiency encapsulation photovoltaic PVB film as described in any one of claims 1-6, characterized in that, The steps are as follows: 1) Premixing: Poly(vinyl butyral) resin, composite plasticizer and hydrolysis stabilizer are added to a high-speed mixer and stirred to allow the composite plasticizer to fully penetrate the resin particles, so as to obtain a uniform and stable premix. 2) Dispersion treatment: Add composite binder, high-efficiency UV shielding agent and dispersant to the premix, and then transfer it to a planetary ball mill for ball milling to obtain a uniformly dispersed mixture; 3) Melt extrusion and filtration: The mixture is added to the hopper of a twin-screw extruder for melt extrusion; the extruder temperature is set in sections: Zone 1 160-165 ℃, Zone 2 170-175 ℃, Zone 3 175-180 ℃, and the die head 178-180 ℃, with a screw speed of 30-50 r / min; after filtering to remove impurities and undispersed particles, the molten material is extruded through a T-shaped flat die, with the die head temperature controlled at 175-180 ℃; 4) Casting and cooling: The extruded melt preform is evenly adhered to the surface of the casting roller. The casting roller adopts three-stage temperature control: the first stage is 80-85℃, the second stage is 70-75℃, and the third stage is 60-65℃. 5) Calendering and finishing: After cooling, the film material enters a two-roll calender. The temperature of the calender rolls is 80-90 ℃. The film material is calendered to the target thickness of 0.38-0.76 mm by adjusting the pressure between the rolls (0.3-0.5 MPa). 6) Then, after thickness measurement and edge trimming, vacuum drying, and winding and packaging, PVB film is obtained.

8. The preparation method according to claim 7, characterized in that, The mixing temperature in step 1) is 80-90 ℃, the stirring speed is 800-1000 r / min, and the stirring is continued for 30-45 min.

9. The preparation method according to claim 7, characterized in that, In step 2), the nanoparticles are ball-milled at a speed of 200-300 r / min for 1-2 hours, with the machine stopped every 30 minutes to take samples and observe the dispersion state, ensuring that the nanoparticles do not agglomerate.

10. The preparation method according to claim 7, characterized in that, In step 4), the temperature fluctuation of the roller surface is controlled to be ≤2℃ by circulating cooling water; the film blank is cooled and shaped on the casting roller for 3-5 seconds to ensure that the film material is initially cured and no internal stress is generated.

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