Preparation method of EVA photovoltaic adhesive film with ultraviolet light conversion effect

Abstract

The invention provides a preparation method of an EVA photovoltaic adhesive film with an ultraviolet light conversion effect, and belongs to the technical field of photovoltaic adhesive films. A europium-doped strontium-barium silicate ultraviolet light conversion material is prepared by performing segmented calcination on a mixture of strontium carbonate, barium carbonate, silicon dioxide and europium oxide in a reducing atmosphere; the material, an ethylene-vinyl acetate copolymer, a cross-linking agent, an assistant cross-linking agent and a silane coupling agent are subjected to melt mixing in an open mill and then are subjected to hot press molding to prepare an adhesive film, and whether a spectral response comprehensive adjustment mode is started or not is judged by measuring the transmittance of an ultraviolet region, the transmittance of a visible region and an external quantum efficiency value. The ratio of a conversion material to a cross-linking system is coordinated and optimized by adopting a multivariable coupling algorithm, and finally, the photovoltaic adhesive film with an ultraviolet light conversion effect is obtained through lamination and curing treatment, so that the technical problem that the photoelectric conversion efficiency of a solar cell is limited due to low ultraviolet light utilization rate is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photovoltaic adhesive film, and particularly relates to a preparation method of an EVA photovoltaic adhesive film with ultraviolet light conversion effect. BACKGROUND

[0002] The ethylene-vinyl acetate copolymer adhesive film for solar cell packaging is a key material for realizing cell protection and optical coupling in photovoltaic modules. The traditional EVA adhesive film optimizes its light transmission performance and packaging reliability by regulating the crosslinking system and adding additives. In the current photovoltaic packaging technology, the ultraviolet light with a wavelength less than 400 nanometers in the solar spectrum cannot be effectively absorbed and utilized by conventional crystalline silicon cells. This part of energy is directly transmitted or absorbed by the adhesive film and converted into heat energy, resulting in light energy loss. The existing technology realizes spectrum conversion by adding fluorescent materials in the adhesive film, but there are problems such as poor compatibility of conversion materials with the matrix, uneven dispersion leading to a decrease in light transmittance, and difficulty in balancing ultraviolet light absorption and visible light transmission. That is, there is a technical problem in the prior art that the low utilization rate of ultraviolet light limits the photoelectric conversion efficiency of solar cells. SUMMARY

[0003] Therefore, the application provides a preparation method of an EVA photovoltaic adhesive film with ultraviolet light conversion effect, which can solve the technical problem that the low utilization rate of ultraviolet light limits the photoelectric conversion efficiency of solar cells in the prior art.

[0004] The application is implemented in the following manner. The preparation method of the EVA photovoltaic adhesive film with ultraviolet light conversion effect mixes strontium carbonate, barium carbonate, silicon dioxide and europium oxide, grinds and dries them, and then prepares an europium-doped strontium barium silicate ultraviolet light conversion material by segmental calcination. The europium-doped strontium barium silicate ultraviolet light conversion material is mixed with ethylene-vinyl acetate copolymer, a crosslinking agent, a co-crosslinking agent and a silane coupling agent, and then melt-kneaded in an open mill. The kneaded product is hot-pressed to form an adhesive film. The ultraviolet transmittance, visible light transmittance and external quantum efficiency value of the adhesive film are measured. When the ultraviolet transmittance, visible light transmittance and external quantum efficiency value meet the preset parameter combination condition, a spectrum response comprehensive adjustment mode is started. The content of the europium-doped strontium barium silicate ultraviolet light conversion material, the content of the crosslinking agent and the content of the co-crosslinking agent are adjusted by a multivariate coupling algorithm to realize coordinated and optimized control. Finally, the adhesive film is subjected to lamination and curing treatment.

[0005] The mass ratio of strontium carbonate, barium carbonate, silicon dioxide and europium oxide is 75-80: 1-2: 10-20: 1-2.5.

[0006] In the mixing and grinding step, anhydrous ethanol is added for grinding for 45-60 min, the drying temperature is 60-80 DEG C, and the drying time is 3-5 h.

[0007] The segmental calcination is performed in an atmosphere sintering furnace, and a mixed gas of nitrogen and hydrogen with a volume ratio of 95:5 is introduced at a flow rate of 100-200 ml / min.

[0008] The segmental calcination comprises increasing the temperature to an intermediate calcination temperature at a rate of 3-5 ℃ / min and keeping the temperature for 1 h, and then continuously increasing the temperature to a final calcination temperature and keeping the temperature for 4-6 h.

[0009] The intermediate calcination temperature is 500-600 ℃, the final calcination temperature is 1250-1350 ℃, and the calcined product is ground to a particle size of 7-10 μm.

[0010] The ethylene-vinyl acetate copolymer accounts for 92.5-98.5% by weight, the europium-doped strontium barium silicate ultraviolet light conversion material accounts for 0.25-1.5% by weight, the crosslinking agent accounts for 0.5-3% by weight, the co-crosslinking agent accounts for 0.5-2% by weight, and the silane coupling agent accounts for 0.25-1.2% by weight.

[0011] The front roller temperature of the open mill is 85-95 ℃, the rear roller temperature is 90-100 ℃, the temperature difference between the front roller temperature and the rear roller temperature is 5-10 ℃, and the melt mixing time is 15-20 min.

[0012] The hot-pressing is performed in a hot press, the upper and lower plate temperatures are 100-120 ℃, the pressure is 30 t, the tabletting time is 15-20 min, and a film with a thickness of 0.2-0.5 mm is obtained.

[0013] The wavelength range of the ultraviolet transmittance is 250-400 nm, and the wavelength range of the visible light transmittance is 400-800 nm.

[0014] The preset parameter combination condition is that the ultraviolet transmittance is 74-78% (not including 74% and 78%), the visible light transmittance is <90%, and the external quantum efficiency value is 82-85 (not including 85).

[0015] The coordinated optimization control specifically comprises adjusting the content of the europium-doped strontium barium silicate ultraviolet light conversion material to 0.8-1.2% by weight, adjusting the content of the crosslinking agent to 1.5-2.5% by weight, and adjusting the content of the co-crosslinking agent to 1.0-1.8% by weight.

[0016] The lamination curing treatment specifically comprises placing the film between two release films and laminating the film in a laminator under vacuum at 140 ℃ for 15 min.

[0017] The ethylene-vinyl acetate copolymer is a copolymer resin with a vinyl acetate content of 18-33% by weight. The crosslinking agent is at least one of dicumyl peroxide, 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, or tert-butyl peroxide. The co-crosslinking agent is at least one of triallyl isocyanurate or trimethylolpropane triacrylate, and the silane coupling agent is vinyltrimethoxysilane.

[0018] This invention synthesizes europium-doped strontium barium silicate ultraviolet light conversion material and then interfacially modifies and composites it with an ethylene-vinyl acetate copolymer matrix. By controlling the amount of conversion material added and optimizing the crosslinking system ratio, a multivariate coupled regulation mechanism for ultraviolet transmittance, visible light transmittance, and external quantum efficiency is established. This method solves the problem of uneven local optical performance caused by poor dispersion of conversion materials in traditional fluorescent conversion films. It improves the interfacial bonding between inorganic fillers and the organic matrix through silane coupling agents, and combines a segmented calcination process to ensure the integrity of the crystal structure and luminescent activity of the conversion material, enabling efficient conversion of ultraviolet light into visible light that can be absorbed by the battery, while maintaining the overall high transmittance of the film. In summary, this invention solves the technical problem mentioned in the background art where low ultraviolet light utilization limits the photoelectric conversion efficiency of solar cells. Attached Figure Description

[0019] Figure 1 This is a flowchart of the method of the present invention.

[0020] Figure 2 The image shows the optical transmittance spectrum of the film in the example.

[0021] Figure 3 The graph shows the parameter evolution curves of the multivariate coupling optimization process in the embodiment. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0023] like Figure 1 The diagram shows a flowchart of a method for preparing an EVA photovoltaic film with ultraviolet light conversion effect provided by the present invention. This method includes the following steps:

[0024] S01. Place strontium carbonate, barium carbonate, silicon dioxide and europium oxide in an agate mortar at a mass ratio of 75 to 80: 1 to 2: 10 to 20: 1 to 2.5, add anhydrous ethanol and grind for 45 to 60 minutes. Then transfer to a petri dish and dry in a forced-air drying oven at 60 to 80°C for 3 to 5 hours.

[0025] S02. The dried precursor powder is placed into an alumina crucible and placed in the constant temperature zone of an atmosphere sintering furnace. A mixture of nitrogen and hydrogen with a volume ratio of 95:5 is introduced and the flow rate is set to 100 to 200 ml per minute. The temperature is increased to the intermediate calcination temperature at a rate of 3 to 5 °C per minute and held for 1 hour.

[0026] S03. Continue heating at the aforementioned rate to the final calcination temperature and hold for 4 to 6 hours. After calcination, remove the powder and grind it to a particle size of 7 to 10 micrometers to obtain europium-doped strontium barium silicate ultraviolet light conversion material.

[0027] S04. Mix 92.5 to 98.5% by weight of ethylene-vinyl acetate copolymer, 0.25 to 1.5% by weight of europium-doped strontium barium silicate ultraviolet conversion material, 0.5 to 3% by weight of crosslinking agent, 0.5 to 2% by weight of co-crosslinking agent and 0.25 to 1.2% by weight of silane coupling agent evenly and then add the mixture to a two-roll mill.

[0028] S05. Set the temperature of the front roller of the open mill to 85 to 95°C and the temperature of the rear roller to 90 to 100°C for melt mixing for 15 to 20 minutes. After mixing, cut to the appropriate size.

[0029] S06. Place the cut mixture into a hot press, set the upper and lower plate temperatures to 100 to 120°C, the pressure to 30 tons, and the pressing time to 15 to 20 minutes to obtain a film with a thickness of 0.2 to 0.5 mm.

[0030] S07. Measure the transmittance of the film in the ultraviolet region of 250 to 400 nanometer wavelength, the transmittance in the visible light region of 400 to 800 nanometer wavelength, and the external quantum efficiency of the encapsulated solar cell.

[0031] S08. When the ultraviolet transmittance ∈ (74%, 78%), the visible transmittance < 90%, and the external quantum efficiency value ∈ [82, 85), the spectral response comprehensive adjustment mode is activated, and the coordinated optimization control of the ultraviolet transmittance, the visible transmittance, and the external quantum efficiency value is achieved through a multivariable coupling algorithm.

[0032] S09. Place the pressed film between two release films and place it in a laminator to laminate under vacuum at 140°C for 15 minutes to complete the curing and crosslinking process of the film.

[0033] The ethylene-vinyl acetate copolymer is a copolymer resin with a vinyl acetate content of 18 to 33% by weight.

[0034] The chemical formula of the europium-doped strontium barium silicate ultraviolet light conversion material is: It absorbs ultraviolet and blue light with wavelengths of 250 to 500 nanometers and converts it into visible light with wavelengths of 450 to 700 nanometers.

[0035] The crosslinking agent is selected from at least one of dicumyl peroxide, 2,5-dimethyl-2,5-ditert-butylperoxyhexane or 2-ethylhexyl carbonate tert-butyl peroxide.

[0036] The crosslinking agent is selected from at least one of triallyl isocyanurate or trimethylolpropane triacrylate, which is used to improve the efficiency of the crosslinking reaction and the crosslinking density.

[0037] The silane coupling agent is vinyltrimethoxysilane, which is used to improve the interfacial compatibility between inorganic fillers and organic resin matrix.

[0038] The intermediate calcination temperature was determined through the following steps: Five parallel experiments were conducted at intermediate calcination temperatures of 450℃, 500℃, 550℃, 600℃, and 650℃, while maintaining other consistent conditions. The weight loss rate and phase purity of the precursor were measured at each temperature. The experimental data were then fitted to obtain the completeness of precursor decomposition. With intermediate calcination temperature The relationship between them can be expressed by the fitting equation as follows: ,in The completeness of the decomposition is 1 when the decomposition is complete. The temperature range corresponding to ≥0.95 is the preferred range of the intermediate calcination temperature. The intermediate calcination temperature ∈ [500, 600]℃ is calculated by the fitting equation.

[0039] The final calcination temperature was determined through the following steps: Seven parallel experiments were conducted at final calcination temperatures of 1150℃, 1200℃, 1250℃, 1300℃, 1350℃, 1400℃, and 1450℃, keeping other conditions consistent. The crystal structure integrity and luminescence intensity of the synthesized product at each temperature were measured. The experimental data were then fitted to obtain the luminescence intensity. With the final calcination temperature The relationship between them can be expressed by the fitting equation as follows: ,in For maximum luminous intensity, when The temperature range corresponding to ≥0.90 is the preferred range of the final calcination temperature. The final calcination temperature ∈ [1250, 1350]℃ is calculated by the fitting equation.

[0040] The temperatures of the upper and lower plates of the hot press are determined through the following steps: Six parallel experiments are set up with upper and lower plate temperatures of 90℃, 100℃, 110℃, 120℃, 130℃, and 140℃, respectively, keeping other conditions consistent. The surface smoothness and internal bubble rate of the adhesive film are measured at each temperature. The experimental data are then fitted to obtain the comprehensive quality index of the adhesive film. With hot pressing temperature The relationship between them can be expressed by the fitting equation as follows: ,in The standard quality index is set to 1. The temperature range corresponding to ≥0.85 is the preferred range of the upper and lower plate temperatures. The upper and lower plate temperatures are calculated to be ∈ [100, 120]℃ through the fitting equation.

[0041] The temperature difference between the front roll and the rear roll of the open mill is set to be 5 to 10°C lower, which is used to generate appropriate shear force during the mixing process and promote the uniform dispersion of the europium-doped strontium barium silicate ultraviolet conversion material in the ethylene vinyl acetate copolymer matrix.

[0042] The atmosphere sintering furnace is purged with a reducing atmosphere of nitrogen and hydrogen to reduce europium ions from trivalent to divalent, forming ions with photoconversion activity. The luminescent center.

[0043] In the segmented heating process, the intermediate calcination temperature holding stage is used for the decomposition reaction of the precursor, and the final calcination temperature holding stage is used for the formation of the crystal structure and grain growth.

[0044] The parameter combination conditions for the ultraviolet transmittance, visible transmittance, and external quantum efficiency value in step S08 are determined through the following steps: 20 groups of film samples with different formulations are selected, and the ultraviolet transmittance, visible transmittance, and external quantum efficiency value of each group are measured. Simultaneously, the power gain of the encapsulated solar cell is measured. Using the power gain as the optimization target, a relationship model between the ultraviolet transmittance, visible transmittance, and external quantum efficiency value and the power gain is established using the response surface methodology. The parameter combination interval corresponding to when the power gain > 1.5% is calculated using the relationship model, and the optimal parameter combination conditions are determined as follows: ultraviolet transmittance ∈ (74%, 78%), visible transmittance < 90%, and external quantum efficiency value ∈ [82, 85).

[0045] The reason for activating the comprehensive spectral response adjustment mode when the parameter combination conditions are met is as follows: Excessive ultraviolet transmittance indicates insufficient absorption of ultraviolet light by the europium-doped strontium barium silicate ultraviolet light conversion material; excessively low visible light transmittance indicates a decrease in the overall light transmission performance of the film; and the external quantum efficiency value being within the specified range indicates that photoelectric conversion is in an optimizable stage. When all three conditions are met simultaneously, by adjusting the content of the europium-doped strontium barium silicate ultraviolet light conversion material to 0.8 to 1.2 weight percentage, adjusting the content of the crosslinking agent to 1.5 to 2.5 weight percentage, and adjusting the content of the co-crosslinking agent to 1.0 to 1.8 weight percentage, the ultraviolet light absorption, visible light transmission, and photoelectric conversion efficiency are coordinated and balanced, thereby maximizing the power gain of the solar cell.

[0046] The multivariable coupling algorithm is implemented using the following steps: The ultraviolet transmittance is denoted as... The transmittance in the visible light region is denoted as... The external quantum efficiency value is denoted as The deviations of the three values ​​from their respective target values ​​are calculated: the target value for ultraviolet transmittance is 76%, the target value for visible transmittance is 92%, and the target value for external quantum efficiency is 83.5. A comprehensive deviation index is then calculated. The statement is as follows: ,in The standard deviation index is set to 1; according to the comprehensive deviation index... Adjusting the content of the europium-doped strontium barium silicate ultraviolet conversion material, the content of the crosslinking agent, and the content of the co-crosslinking agent, when... Coordinated optimization control is completed when the value is less than 0.05.

[0047] The effect of the comprehensive spectral response adjustment mode is that, through the coordinated optimization control of the multivariable coupling algorithm, the film can improve the ultraviolet light utilization rate while maintaining high visible light transmittance, avoid performance imbalance caused by single parameter optimization, and ultimately improve the photoelectric conversion performance of the encapsulated solar cell by 1.5 to 2.0 percentage points across the entire spectrum.

[0048] The specific implementation methods of the above steps are described in detail below.

[0049] The specific implementation of step S01 involves accurately weighing strontium carbonate, barium carbonate, silicon dioxide, and europium oxide in a mass ratio of 75 to 80: 1 to 2: 10 to 20: 1 to 2.5 and placing them into an agate mortar. An appropriate amount of anhydrous ethanol is added as a grinding medium, and the mixture is mechanically ground for 45 to 60 minutes. During the grinding process, the role of anhydrous ethanol is to reduce powder agglomeration and promote uniform mixing of the components. After grinding, the mixed slurry is transferred to a petri dish and dried in a forced-air drying oven at 60 to 80°C for 3 to 5 hours to remove the solvent. The purpose of this step is to prepare a uniformly dispersed precursor powder, providing a homogenized raw material basis for the subsequent sintering reaction.

[0050] The specific implementation of step S02 involves loading the dried precursor powder into a corundum crucible and placing it in the constant temperature zone of an atmosphere sintering furnace. A reducing atmosphere is established by introducing a nitrogen and hydrogen mixture with a volume ratio of 95:5, and the gas flow rate is set to 100 to 200 ml per minute to maintain a stable atmosphere inside the furnace. The temperature is linearly increased to the intermediate calcination temperature at a rate of 3 to 5 °C per minute using a programmed temperature control method and held at that temperature for 1 hour. In this stage, the decomposition reaction of the precursor is achieved using the principle of chemical thermodynamics. By controlling the heating rate, phase inhomogeneity caused by local overheating is avoided. The intermediate calcination temperature is determined by using a correlation analysis method between weight loss rate and phase purity. The preferred temperature range is determined to be 500 to 600 °C by fitting the exponential relationship between the complete decomposition of the precursor and the calcination temperature.

[0051] The specific implementation of step S03 involves maintaining the same heating rate to raise the temperature to the final calcination temperature after intermediate calcination and holding it at that temperature for 4 to 6 hours. In this stage, the solid-state reaction kinetics principle is applied to achieve crystal structure formation and grain growth. The final calcination temperature is determined using a Gaussian correlation model between luminescence intensity and temperature. By fitting the relationship between luminescence intensity and calcination temperature, the preferred temperature range is determined to be 1250 to 1350°C. After calcination, the product is removed and mechanically ground to control the powder particle size to within the range of 7 to 10 micrometers. This particle size range ensures light conversion efficiency while avoiding enhanced light scattering due to excessively large particle size. The final product is chemically formulated as follows: Europium-doped strontium barium silicate ultraviolet light conversion material.

[0052] The specific implementation of step S04 involves accurately weighing 92.5 to 98.5% of ethylene vinyl acetate copolymer with a vinyl acetate content of 18 to 33%, 0.25 to 1.5% of europium-doped strontium barium silicate ultraviolet conversion material, 0.5 to 3% of crosslinking agent, 0.5 to 2% of co-crosslinking agent, and 0.25 to 1.2% of silane coupling agent according to their weight percentages. After preliminary mixing by mechanical mixing, the mixture is added to an open mill. The proportions of each component are designed based on the compatibility principle of multi-component composite materials. The role of the silane coupling agent is to improve the interfacial bonding strength between the inorganic filler and the organic matrix.

[0053] The specific implementation of step S05 is to set the temperature of the front roll of the open mill to 85 to 95°C and the temperature of the rear roll to 90 to 100°C, forming a temperature gradient of 5 to 10°C to generate appropriate shear stress during the mixing process. The mixture is thoroughly mixed for 15 to 20 minutes using a melt mixing method. This process applies the principle of polymer processing rheology and achieves uniform dispersion of europium-doped strontium barium silicate ultraviolet conversion material in the ethylene vinyl acetate copolymer matrix through temperature gradient control. After the mixing is completed, the mixture is cut to a size suitable for subsequent tableting.

[0054] The specific implementation of step S06 is to place the cut compound into a hot press, set the upper and lower plate temperatures to 100 to 120°C, the pressure to 30 tons, and the pressing time to 15 to 20 minutes for hot pressing. This process applies the principle of polymer melt flow, and achieves densification and smoothing of the compound through the synergistic effect of temperature and pressure. The hot pressing temperature is determined by using a quadratic polynomial correlation model between the comprehensive quality index of the film and temperature. By fitting the comprehensive index of surface smoothness and internal bubble rate, the preferred temperature range is determined to be 100 to 120°C, and finally a film with a thickness of 0.2 to 0.5 mm is obtained.

[0055] The specific implementation of step S07 is to use an ultraviolet-visible spectrophotometer to measure the transmittance of the film in the ultraviolet region of 250 to 400 nanometers and the transmittance in the visible region of 400 to 800 nanometers, and to use a solar cell quantum efficiency testing system to measure the external quantum efficiency value of the encapsulated solar cell. The purpose of this step is to obtain the key parameters of the film's optical performance and photoelectric conversion performance, so as to provide a data basis for subsequent performance optimization.

[0056] The specific implementation of step S08 involves determining whether the ultraviolet transmittance is within the open range of 74% to 78%, whether the visible transmittance is less than 90%, and whether the external quantum efficiency is within the left-closed to right-open range of 82 to 85. When all three conditions are met simultaneously, the spectral response comprehensive adjustment mode is activated. The determination of these conditions is based on a multi-parameter optimization model established using the response surface methodology. The optimal parameter combination range was determined by analyzing the power gain data of 20 different formulation samples. The reason for activating the adjustment mode is that excessively high ultraviolet transmittance indicates insufficient ultraviolet light absorption, excessively low visible transmittance indicates a decrease in overall light transmission performance, and an external quantum efficiency value within this range indicates that photoelectric conversion is in an optimizable stage. A multivariate coupling algorithm is used to achieve coordinated optimization control of ultraviolet transmittance, visible transmittance, and external quantum efficiency. Specifically, the content of europium-doped strontium barium silicate ultraviolet light conversion material is adjusted to 0.8% to 1.2%, the crosslinking agent content to 1.5% to 2.5%, and the co-crosslinking agent content to 1.0% to 1.8%. The multivariate coupling algorithm is implemented by calculating the relative deviations of the ultraviolet transmittance, visible transmittance, and external quantum efficiency values ​​from their respective target values ​​of 76%, 92%, and 83.5, respectively. A comprehensive deviation index is calculated based on weighting coefficients of 0.4, 0.3, and 0.3. Coordinated optimization control is completed when the ratio of the comprehensive deviation index to the standard deviation index is less than 0.05.

[0057] The specific implementation of step S09 is to place the pressed adhesive film between two release films to prevent adhesion, and then place it in a laminator to laminate for 15 minutes under a temperature of 140°C and a vacuum. This process applies the principle of crosslinking reaction kinetics, and achieves crosslinking between ethylene vinyl acetate copolymer molecular chains by heating to activate the free radical reaction of the crosslinking agent and the co-crosslinking agent. The vacuum condition is used to remove air bubbles inside the adhesive film and improve the lamination quality. Finally, the curing and crosslinking treatment of the adhesive film is completed to form a photovoltaic encapsulation material with a three-dimensional network structure.

[0058] It should be noted that the key technical ideas of this invention include the application of segmented heating sintering process, coordinated optimization control of multivariate coupling algorithm, and ion valence state regulation under reducing atmosphere. The segmented heating sintering process achieves full decomposition of the precursor through an intermediate calcination stage, avoiding phase inhomogeneity and crystal defects caused by one-step heating. The final calcination stage promotes grain growth and crystal structure perfection through high-temperature long-term holding. Compared with the traditional single-stage sintering process, this method significantly improves the luminescence intensity and light conversion efficiency of the fluorescent material. The multivariate coupling algorithm establishes a correlation model between ultraviolet transmittance, visible light transmittance, and external quantum efficiency, achieving coordinated optimization of multiple performance parameters. This avoids the problem of sacrificing other performance parameters for improving one performance in traditional single-parameter optimization methods, enabling the film to achieve optimal comprehensive performance across the entire spectrum. Ion valence state regulation under reducing atmosphere reduces europium ions from trivalent to divalent through the reduction effect of a nitrogen-hydrogen mixture, forming divalent europium luminescent centers with strong luminescence characteristics. Compared with air atmosphere sintering, this method significantly improves the material's ultraviolet light absorption capacity and light conversion efficiency. The synergistic effect of these three key technological approaches lies in the fact that the segmented sintering process ensures the high-quality synthesis of fluorescent materials, the control of the reducing atmosphere endows the materials with excellent light conversion performance, and the multivariate coupling algorithm achieves the best match between material performance and the overall performance of the encapsulated film through precise formulation control. The three work together to enable the encapsulated solar cells to significantly improve the utilization efficiency of ultraviolet light while maintaining high light transmittance. Compared with traditional single optimization methods, this synergistic technical route achieves a systematic improvement in the photoelectric conversion efficiency of photovoltaic modules across the entire spectrum.

[0059] It should be noted that this invention also solves the following technical problem: In the synthesis of fluorescent conversion materials, traditional single-step calcination methods cannot simultaneously ensure the complete decomposition of the precursor and the complete formation of the crystal structure, resulting in residual unreacted substances or lattice defects in the synthesized product, affecting the stability of light conversion efficiency. This invention establishes a quantitative relationship model between intermediate calcination temperature and the completeness of precursor decomposition, as well as a correlation function between final calcination temperature and luminescence intensity. It determines that an intermediate calcination temperature of 500 to 600 degrees Celsius is used for precursor decomposition, and a final calcination temperature of 1250 to 1350 degrees Celsius is used for crystal growth. The segmented calcination process allows the gas generated by carbonate decomposition to be fully released at the intermediate temperature stage, avoiding lattice defects caused by gas escape at high temperatures. Simultaneously, the final temperature stage provides sufficient thermodynamic driving force to promote grain growth and form a regular crystal structure, ensuring that divalent europium ions uniformly occupy lattice positions to form effective luminescent centers, thereby obtaining a material with high luminescence intensity and stable light conversion performance. Furthermore, this invention also solves the problem of local fluctuations in optical performance caused by uneven dispersion of conversion materials in the polymer matrix. By setting a temperature difference of 5 to 10 degrees Celsius lower between the front and rear rollers of the open mill, a material flow trend from the low-temperature roller to the high-temperature roller is formed during the mixing process. This generates a continuous shear stress field that breaks up the agglomerates of the conversion materials. Combined with the organic coating layer formed on the particle surface by the silane coupling agent to reduce the surface energy, the nanoscale conversion particles are uniformly dispersed in the polymer melt. This avoids the problem of excessive scattering of visible light in local high-concentration areas and insufficient absorption of ultraviolet light in low-concentration areas, ensuring the consistency of optical performance of the film in large-area applications.

[0060] Specifically, the principle of this invention is as follows: The technical solution of this invention can solve the problem of low ultraviolet light utilization. Its principle lies in constructing a highly efficient light conversion system by precisely controlling the synthesis conditions of europium-doped strontium barium silicate materials. Segmented calcination is performed under a reducing atmosphere. The intermediate calcination stage allows the precursor to fully decompose and initially form a crystal structure. The final calcination stage promotes grain growth and reduces trivalent europium ions to divalent europium luminescent centers with broadband emission characteristics. These luminescent centers can absorb ultraviolet and blue light from 250 to 500 nanometers and convert them into visible light from 450 to 700 nanometers. During the film preparation process, the shear force generated by the temperature difference between the front and rear rollers of the open mill promotes uniform dispersion of the conversion material. The silane coupling agent forms an organic functional group bridging layer on the surface of inorganic particles to reduce interfacial energy. The synergistic effect of the crosslinking agent and the co-crosslinking agent maintains the light transmittance of the network structure while fixing the spatial distribution of the conversion particles. When the transmittance in the ultraviolet region, the transmittance in the visible region, and the external quantum efficiency are all within a certain range, the multivariable coupling algorithm is activated to achieve coordinated optimization of the three parameters by adjusting the ratio of the conversion material to the crosslinking system. This enhances ultraviolet light absorption while avoiding excessive loss of visible light transmittance, thereby improving photoelectric conversion performance across the entire spectrum.

[0061] The following provides a specific embodiment 1 of the present invention, and the specific implementation of each step in this embodiment 1 is described in detail below.

[0062] The specific implementation of step S02 involves loading the dried precursor powder into a corundum crucible and placing it in the constant temperature zone of an atmosphere sintering furnace, then introducing a mixture of 95:5 by volume. and A reducing atmosphere was established using a mixed gas, with a gas flow rate set to 100-200 mL / min to maintain a stable atmosphere within the furnace. A programmed temperature rise control method was employed to linearly increase the temperature to the intermediate calcination temperature at a rate of 3-5 °C / min and hold at that temperature for 1 hour. The intermediate calcination temperature was determined by the relationship between the complete decomposition of the precursor and temperature, expressed by the fitted equation as follows:

[0063] ;

[0064] In the formula, The degree of complete decomposition of the precursor is dimensionless and ranges from 0 to 1. The degree of complete decomposition is 1, which is dimensionless. The intermediate calcination temperature is expressed in °C. The numerical part representing the intermediate calcination temperature is dimensionless; 400 is the reference temperature value, dimensionless, corresponding to the actual temperature of 400℃, which is the starting temperature at which carbonate decomposition begins; 100 is the temperature characteristic coefficient value, dimensionless, corresponding to the actual temperature scale of 100℃, characterizing the temperature sensitivity of the decomposition reaction.

[0065] The parameter acquisition method is as follows:

[0066] The precursor was obtained experimentally, including the following steps: Step 1: Five parallel experiments were set up with intermediate calcination temperatures of 450℃, 500℃, 550℃, 600℃, and 650℃; Step 2: The heating rate, atmosphere flow rate, and other conditions were kept consistent; Step 3: The weight loss rate of the precursor was measured at each temperature; Step 4: The phase purity was determined by X-ray diffraction analysis; Step 5: The completeness of decomposition was calculated based on the weight loss rate and phase purity. . The default value is 1. The calcination temperature value set for the experiment. When When the value is ≥0.95, the preferred range for intermediate calcination temperature calculated by the above fitting equation is 500 to 600℃. This equation uses an exponential decay model to describe the thermal decomposition kinetics of the precursor, by constructing the temperature term as... The dimensionless exponential factor makes the left side of the equation a dimensionless ratio and the right side a dimensionless exponential function value. This model can accurately predict the degree of decomposition of precursors at different temperatures, providing a theoretical basis for determining the optimal intermediate calcination temperature.

[0067] The specific implementation of step S03 involves maintaining the same heating rate to raise the temperature to the final calcination temperature after the intermediate calcination and holding it at that temperature for 4 to 6 hours. The final calcination temperature is determined by the relationship between luminescence intensity and temperature, expressed by the following fitted equation:

[0068] ;

[0069] In the formula, The luminescence intensity of the synthesized product is expressed in arbitrary units. The maximum luminous intensity is expressed in arbitrary units, and is related to... Same units; The final calcination temperature is expressed in °C. The numerical part representing the final calcination temperature is dimensionless; 1300 is the optimal temperature value, dimensionless, corresponding to an actual temperature of 1300℃, i.e. The most complete crystal structure and The optimal concentration of luminescent centers; 80 is the temperature broadening coefficient, dimensionless, corresponding to the actual temperature scale of 80℃, characterizing the width of the temperature window for crystal growth.

[0070] The parameter acquisition method is as follows:

[0071] The method employed was experimental, including the following steps: Step 1: Seven parallel experiments were set up, with final calcination temperatures of 1150℃, 1200℃, 1250℃, 1300℃, 1350℃, 1400℃, and 1450℃, respectively; Step 2: Other process conditions were kept consistent; Step 3: The luminescence intensity of the synthesized product in the wavelength range of 450 to 700 nanometers at each temperature was measured using a fluorescence spectrometer; Step 4: The integrity of the crystal structure was analyzed using an X-ray diffractometer. Take the maximum luminous intensity value measured in the experiment. The calcination temperature value set for the experiment. When When the value is ≥0.90, the preferred range for the final calcination temperature, calculated using the above fitting equation, is 1250 to 1350℃. After calcination, the product is removed and mechanically ground to control the powder particle size within the range of 7 to 10 micrometers, ultimately yielding the product with the chemical formula […]. Europium-doped barium strontium silicate ultraviolet light conversion material. The equation uses a Gaussian function to describe the change in luminescence intensity with temperature during crystal structure formation, by constructing the temperature term as... The dimensionless factor is used as the exponential term, so that the left side of the equation is the dimensionless intensity ratio and the right side is the dimensionless exponential function value. This model can accurately predict the luminescence performance of fluorescent materials at different calcination temperatures, and provide a temperature control basis for the preparation of high-efficiency ultraviolet light conversion materials.

[0072] The specific implementation of step S06 involves placing the cut compound into a hot press, setting the upper and lower plate temperatures to 100-120°C, the pressure to 30 tons, and the pressing time to 15-20 minutes for hot pressing. The hot pressing temperature is determined by the relationship between the film's overall quality index and temperature, expressed by the following fitted equation:

[0073] ;

[0074] In the formula, It is the overall quality index of the film, dimensionless, and its value ranges from 0 to 1; This is the standard quality index, with a value of 1, and is dimensionless. This refers to the hot-pressing temperature, expressed in °C. The numerical part representing the hot-pressing temperature is dimensionless; 80 is the reference temperature value, dimensionless, corresponding to the actual temperature of 80℃, which is the temperature at which the ethylene-vinyl acetate copolymer begins to soften; 110 is the optimal temperature value, dimensionless, corresponding to the actual temperature of 110℃, which is the temperature point at which the quality index reaches its peak; 20 and 30 are the temperature characteristic coefficient values, dimensionless, corresponding to the actual temperature scales of 20℃ and 30℃, respectively, representing the temperature scales of linear promoting effect and secondary inhibiting effect.

[0075] Overall quality index of adhesive film The calculation formula is expressed as follows:

[0076] ;

[0077] In the formula, The roughness of the adhesive film is expressed in micrometers. For reference surface roughness, the unit is micrometers, and the empirical value is 5 micrometers; This is the numerical part of the bubble rate inside the adhesive film, dimensionless, that is, the actual bubble rate divided by the percentage. The numerical part of the reference bubble rate is dimensionless, with an empirical value of 10; 0.6 and 0.4 are weighting coefficients, dimensionless, representing the influence weights of surface smoothness and internal bubble rate on film quality, respectively.

[0078] The parameter acquisition method is as follows:

[0079] It is obtained through the above calculation formula. The surface roughness parameters of the film were obtained experimentally, including the following steps: Step 1: Six parallel experiments were set up with upper and lower plate temperatures of 90℃, 100℃, 110℃, 120℃, 130℃, and 140℃, respectively; Step 2: The pressure of 30 tons and the tableting time of 15 to 20 minutes were kept constant; Step 3: The surface roughness parameters of the film at each temperature were measured using a surface profilometer. . The method used was experimental. Step 1: Observe the cross-section of the film using an optical microscope; Step 2: Count the number of air bubbles per unit area and the total area of ​​the air bubbles; Step 3: Calculate the air bubble rate as a percentage of the air bubble area to the total area, denoted as [missing information]. Step 4: Extract the numerical portion Used for calculations. The empirical value is 5 micrometers. The experience value is 10. The hot-pressing temperature value set for the experiment. When When the coefficient of performance (COP) is ≥0.85, the optimal range for hot-pressing temperature, calculated using the above fitting equation, is 100 to 120°C, ultimately yielding a film with a thickness of 0.2 to 0.5 mm. This fitting equation uses a quadratic polynomial model to describe the effect of hot-pressing temperature on film quality. The first term... The first term is linear, characterizing the effect of temperature increase on material fluidity; the second term... The quadratic term characterizes the negative effects of excessively high temperatures, such as material degradation and increased bubble formation. By normalizing the temperature factor to a dimensionless form, the left side of the equation becomes a dimensionless mass ratio, and the right side becomes a dimensionless polynomial. This model can accurately predict the combined impact of hot-pressing temperature on the surface smoothness and internal bubble rate of the adhesive film, providing a quantitative basis for optimizing hot-pressing process parameters. The mass index calculation formula uses the surface roughness ratio... ratio of bubble rate Normalize them separately to achieve a unified evaluation of parameters with different dimensions.

[0080] The specific implementation of step S08 involves determining whether the ultraviolet transmittance is within the open range of 74% to 78%, whether the visible transmittance is less than 90%, and whether the external quantum efficiency is within the left-closed to right-open range of 82 to 85. When all three conditions are met simultaneously, the spectral response integrated adjustment mode is activated. These conditions are determined using a multi-parameter optimization model established by the response surface methodology. The optimal parameter combination range is obtained by analyzing the power gain data of 20 different formulation samples. The multivariate coupling algorithm achieves coordinated optimization control by calculating the comprehensive deviation index, which is expressed as follows:

[0081] ;

[0082] In the formula, This is a comprehensive deviation index, dimensionless. The standard deviation index has a value of 1 and is dimensionless. Ultraviolet transmittance, in percentages (%) The numerical part representing the transmittance in the ultraviolet region is dimensionless. The transmittance in the visible light region is expressed as % (%). The numerical part representing the transmittance in the visible light region is dimensionless. 76 represents the external quantum efficiency value, dimensionless, ranging from 0 to 100; 76 represents the numerical part of the target value for ultraviolet transmittance, dimensionless, corresponding to the actual target value of 76%; 92 represents the numerical part of the target value for visible light transmittance, dimensionless, corresponding to the actual target value of 92%; 83.5 represents the target value for external quantum efficiency, dimensionless; 0.4, 0.3, and 0.3 are weighting coefficients, dimensionless, representing the influence weights of ultraviolet transmittance, visible light transmittance, and external quantum efficiency on the performance of solar cells, respectively.

[0083] The parameter acquisition method is as follows: The measurements were obtained using a UV-Vis spectrophotometer in the 250 to 400 nanometer wavelength range. The measurements were obtained using a UV-Vis spectrophotometer in the 400 to 800 nanometer wavelength range. The external quantum efficiency of a packaged solar cell was determined using a solar cell quantum efficiency testing system. Three target values ​​of 76%, 92%, and 83.5% were obtained through response surface methodology optimization, corresponding to the optimal parameter combination when the power gain is greater than 1.5%. Weighting coefficients of 0.4, 0.3, and 0.3 were determined based on the influence of each parameter on the solar cell performance. The default value is 1. When When the value is less than 0.05, coordinated optimization control is achieved. This is accomplished by adjusting the content of europium-doped strontium barium silicate ultraviolet light conversion material to 0.8–1.2 wt%, the crosslinking agent content to 1.5–2.5 wt%, and the co-crosslinking agent content to 1.0–1.8 wt%, thus achieving a coordinated balance between ultraviolet light absorption, visible light transmission, and photoelectric conversion efficiency. The equation uses a weighted absolute deviation model to describe the multi-parameter coordinated optimization process, normalizing the deviations of the three parameters to their respective target values. , and The model is constructed as a dimensionless relative deviation, with the left side of the equation being the dimensionless deviation ratio and the right side being the dimensionless weighted sum. The weighting coefficients reflect that the importance of ultraviolet transmittance to ultraviolet light utilization is slightly higher than that of visible light transmittance and external quantum efficiency. This model can maximize ultraviolet light conversion efficiency while ensuring high visible light transmittance, thereby improving the photoelectric conversion performance of the encapsulated solar cell in the full spectrum range by 1.5 to 2.0 percentage points.

[0084] In this embodiment, the specific implementation methods of steps S01, S04, S05, S07, and S09 are the same as those described above, and will not be repeated in detail here.

[0085] The precursor decomposition completeness equation designed in this invention is based on the principle of thermal decomposition kinetics and uses an exponential function. Accurately describe the decomposition behavior of carbonate precursors as temperature increases.

[0086] This equation can quantify the degree of decomposition at different temperatures, avoiding precursor residues due to insufficient temperature or phase decomposition due to excessive temperature, thus providing a temperature control basis for the preparation of high-purity europium-doped barium strontium silicates. The luminescence intensity equation uses a Gaussian function. Simulate the changes in luminescence properties during the formation of crystal structures.

[0087] This equation reveals the effect of the final calcination temperature on... Crystal structure integrity and The influence of luminescent center concentration was investigated, and the ultraviolet light conversion efficiency of the fluorescent material was maximized by precisely controlling the calcination temperature. The comprehensive quality index equation for the film was also established. The dual effect of hot pressing temperature on the quality of film forming is described by combining linear and quadratic terms.

[0088] This equation can predict the surface smoothness and internal bubble rate of the encapsulant film at different temperatures, avoiding insufficient flowability due to excessively low temperatures or material degradation caused by excessively high temperatures, thus ensuring the preparation of high-quality photovoltaic encapsulant films. The quality index calculation formula includes... Surface roughness and bubble rate are unified into a comprehensive quality evaluation system using a weighted normalization method. Comprehensive deviation index equation. The ultraviolet transmittance, visible transmittance, and external quantum efficiency values ​​are optimized by using a multivariate weighted normalization method.

[0089] This equation unifies performance parameters of different dimensions into a dimensionless deviation index, assigns differentiated weights to each parameter based on its contribution to the overall performance of the solar cell, and enables the encapsulant film to achieve the optimal balance between high efficiency in ultraviolet light conversion and high transmittance in visible light, ultimately achieving a significant improvement in the power output of the solar cell. This optimization strategy avoids the performance imbalance problem caused by single parameter optimization and ensures that the photovoltaic module obtains the best photoelectric conversion efficiency across the entire spectrum.

[0090] It should be noted that the variables involved in this invention are explained in detail in Table 1.

[0091] Table 1. Variable Explanation Table

[0092]

[0093] To better understand and implement this invention, a specific application scenario of this invention is provided below as Example 2: During the development of high-efficiency photovoltaic module encapsulation materials, a technical team optimized the ultraviolet light conversion EVA film preparation technology of this invention to address the problem of photoelectric conversion efficiency loss caused by insufficient utilization of ultraviolet light by solar cells. The team selected ethylene vinyl acetate copolymer with a vinyl acetate content of 28% as the matrix material and prepared a photovoltaic encapsulation film with spectral modulation function according to a specific process flow.

[0094] In the precursor preparation stage, the technical team placed 78g of strontium carbonate, 1.5g of barium carbonate, 15g of silicon dioxide, and 1.8g of europium oxide into an agate mortar, added 150mL of anhydrous ethanol, and ground for 52 minutes, maintaining uniform force during grinding to ensure thorough mixing of all components. After grinding, the slurry was transferred to a petri dish and dried in a 70℃ forced-air drying oven for 4 hours, yielding a light yellow powdered precursor. The team then placed the dried precursor powder into a corundum crucible and placed it in the constant-temperature zone of an atmosphere sintering furnace, introducing a nitrogen-hydrogen mixture with a volume ratio of 95:5 at a flow rate of 150mL / min. The temperature was increased to an intermediate calcination temperature of 550℃ at a rate of 4℃ / min and held for 1 hour. This stage mainly involved the decomposition reaction of carbonates, releasing... The gas forms an oxide intermediate. The temperature is then increased to the final calcination temperature of 1300℃ at the same rate and held for 5 hours. This stage promotes crystal structure formation and grain growth. After calcination, the powder is removed and ground to a particle size of 8 μm using a planetary ball mill, yielding a product with the chemical formula […]. Europium-doped strontium barium silicate ultraviolet light conversion material.

[0095] During the film formulation design phase, the technical team weighed 95.5g of ethylene-vinyl acetate copolymer, 1.0g of europium-doped strontium barium silicate UV conversion material, 2.0g of dicumyl peroxide as a crosslinking agent, 1.5g of triallyl isocyanurate as a co-crosslinking agent, and 0.8g of vinyltrimethoxysilane as a silane coupling agent. After uniform mixing, the components were added to a two-roll mill. The two-roll mill was set with a front roll temperature of 90℃ and a rear roll temperature of 95℃, a 5℃ temperature difference between the front and rear rolls, to create appropriate shear force during the mixing process, promoting the uniform dispersion of the UV conversion material in the polymer matrix. After 18 minutes of melt mixing, the mixture was pale yellow with a smooth surface. The technical team then cut it into 300mm × 300mm square sheets.

[0096] The cut compound was placed in a hot press, with the upper and lower plate temperatures set at 110℃, pressure at 30 tons, and pressing time at 18 minutes. After hot pressing, a 0.35mm thick film was obtained. The technical team used a UV-Vis spectrophotometer to measure the optical properties of the film, such as... Figure 2As shown, the transmittance in the ultraviolet region (250-400 nm) was measured to be 76.5%, and the transmittance in the visible light region (400-800 nm) was 88.2%. Subsequently, the film was encapsulated with a polycrystalline silicon solar cell, and the external quantum efficiency was measured to be 83.8 using a quantum efficiency testing system.

[0097] Based on the test results, the technical team found that the ultraviolet transmittance of 76.5% was within the range of 74% to 78%, the visible light transmittance of 88.2% was less than 90%, and the external quantum efficiency of 83.8 was within the range of 82 to 85. All three parameters simultaneously met the conditions for activating the comprehensive spectral response adjustment mode. Figure 3 As shown, the technical team used a multivariate coupling algorithm for coordinated optimization control, calculating a transmittance deviation of 0.5% in the ultraviolet region, a transmittance deviation of 3.8% in the visible light region, and an external quantum efficiency deviation of 0.3, with a comprehensive deviation index. The value was 0.032, which is less than the control threshold of 0.05. Based on the deviation analysis results, the technical team fine-tuned the content of europium-doped strontium barium silicate ultraviolet light conversion material to 1.05%, the crosslinking agent content to 2.2%, and the co-crosslinking agent content to 1.6%. They then re-formulated the film and tested it. After the adjustment, the ultraviolet transmittance decreased to 75.8%, the visible light transmittance increased to 91.5%, and the external quantum efficiency was optimized to 83.6.

[0098] After optimizing the encapsulant film formulation, the technical team placed the pressed encapsulant film between two release films and laminated it in a laminator under vacuum at 140°C for 15 minutes to complete the curing and cross-linking process. The cured encapsulant film was then used to encapsulate the module with tempered glass, solar cells, and backsheet materials. The encapsulated solar cells underwent performance testing under standard test conditions, as shown in Table 2.

[0099] Table 2 Comparison of photovoltaic performance parameters of solar cells before and after optimization

[0100]

[0101] Performance test results show that the ultraviolet conversion EVA film prepared using the technical solution of this invention increases the solar cell conversion efficiency from 18.75% to 19.32%, achieving a power gain of 1.87%. Compared to traditional EVA films, this invention introduces europium-doped strontium barium silicate ultraviolet conversion material into the film, absorbing and converting the 250-400nm ultraviolet light, which was originally unusable by solar cells, into visible light in the 450-700nm band, thus expanding the spectral response range of the solar cell. Simultaneously, the segmented calcination process precisely controls the crystal structure formation process, ensuring… The effective formation of luminescent centers and the achievement of a coordinated balance between ultraviolet light absorption, visible light transmission, and photoelectric conversion efficiency through a comprehensive spectral response adjustment mode avoid performance imbalances caused by optimizing a single parameter. The introduction of a reducing atmosphere reduces trivalent europium ions to divalent europium ions with photoconversion activity. The use of silane coupling agents improves the interfacial compatibility between the inorganic fluorescent material and the organic resin matrix, reducing light scattering losses at the interface. This maximizes ultraviolet light utilization while maintaining high visible light transmittance, achieving an overall improvement in the photoelectric conversion performance of the solar cell across the entire spectrum.

[0102] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing EVA photovoltaic adhesive film with ultraviolet light conversion effect, characterized in that, The strontium barium silicate ultraviolet light conversion material doped with europium is prepared by mixing, grinding and drying strontium carbonate, barium carbonate, silicon dioxide and europia, and then performing staged calcination, the strontium barium silicate ultraviolet light conversion material doped with europium is mixed with ethylene-vinyl acetate copolymer, crosslinking agent, co-crosslinking agent and silane coupling agent, and then melt-kneaded in an open mill, the kneaded material is hot-pressed to form a rubber film, the ultraviolet region transmittance, the visible light region transmittance and the external quantum efficiency value of the rubber film are measured, when the ultraviolet region transmittance, the visible light region transmittance and the external quantum efficiency value meet the preset parameter combination condition, a spectral response comprehensive adjustment mode is started, the content of the strontium barium silicate ultraviolet light conversion material doped with europium, the content of the crosslinking agent and the content of the co-crosslinking agent are adjusted to realize coordinated optimization control through a multivariate coupling algorithm, and finally the rubber film is laminated and cured.

2. The method for preparing EVA photovoltaic adhesive film with ultraviolet light conversion effect according to claim 1, characterized in that, The mass ratio of the strontium carbonate, the barium carbonate, the silicon dioxide and the europia is 75-80: 1-2: 10-20: 1-2.

5.

3. The method for preparing the EVA photovoltaic adhesive film with ultraviolet light conversion effect according to claim 2, characterized in that, In the mixing and grinding step, anhydrous ethanol is added, the grinding time is 45-60 min, the drying temperature is 60-80 DEG C, and the drying time is 3-5 h.

4. The method for preparing the EVA photovoltaic adhesive film with ultraviolet light conversion effect according to claim 3, characterized in that, The staged calcination is performed in an atmosphere sintering furnace, a mixed gas of nitrogen and hydrogen with a volume ratio of 95:5 is introduced, and the flow rate is 100-200 ml / min.

5. The method for preparing the EVA photovoltaic adhesive film with ultraviolet light conversion effect according to claim 4, characterized in that, The staged calcination includes heating at a rate of 3-5 DEG C / min to an intermediate calcination temperature and keeping the temperature for 1 h, continuously heating to a final calcination temperature and keeping the temperature for 4-6 h.

6. The method for preparing the EVA photovoltaic adhesive film with ultraviolet light conversion effect according to claim 5, characterized in that, The intermediate calcination temperature is 500-600 DEG C, the final calcination temperature is 1250-1350 DEG C, and the particle size after calcination is 7-10 mu m.

7. The method for preparing the EVA photovoltaic adhesive film with ultraviolet light conversion effect according to claim 6, characterized in that, The weight percentage of the ethylene-vinyl acetate copolymer is 92.5-98.5, the weight percentage of the strontium barium silicate ultraviolet light conversion material doped with europium is 0.25-1.5, the weight percentage of the crosslinking agent is 0.5-3, the weight percentage of the co-crosslinking agent is 0.5-2, and the weight percentage of the silane coupling agent is 0.25-1.

2.

8. The method for preparing the EVA photovoltaic adhesive film with ultraviolet light conversion effect according to claim 7, characterized in that, The front roll temperature of the open mill is 85-95 DEG C, the rear roll temperature is 90-100 DEG C, the temperature difference between the front roll temperature and the rear roll temperature is 5-10 DEG C, and the melt-kneading time is 15-20 min.

9. The method for preparing the EVA photovoltaic adhesive film with ultraviolet light conversion effect according to claim 8, characterized in that, The hot-pressing is performed in a hot press, the temperature of the upper and lower plates is 100-120 DEG C, the pressure is 30 t, the tabletting time is 15-20 min, and the rubber film with a thickness of 0.2-0.5 mm is obtained.

10. The method for preparing an EVA photovoltaic film with ultraviolet light conversion effect according to claim 9, characterized in that, The wavelength band of the ultraviolet region transmittance is 250-400 nm, and the wavelength band of the visible light region transmittance is 400-800 nm.

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