Up-conversion material, preparation method thereof, up-conversion adhesive film and solar cell

Abstract

The invention discloses an up-conversion material, a preparation method thereof, an up-conversion adhesive film and a solar cell. The upconversion material comprises rare earth element-inorganic matrix composite particles and a surface modifier coating the surfaces of the rare earth element-inorganic matrix composite particles; the surface modifier is a silane coupling agent and / or polyethylene glycol; the rare earth element-inorganic matrix composite particles comprise an inorganic matrix and rare earth element ions; the inorganic matrix is selected from one or more of SrF2, BaF2, NaYF4, NaLaF4, NaY (WO4) 2, KY (WO4) 2, TiO2, Y2O3, YVO4 and LaVO4; the inorganic matrix is selected from one or more of SrF2, BaF2, NaYF4, NaLaF4, NaY (WO4) 2, KY (WO4) 2; the rare earth element ions are composed of Yb < 3 + > as a first rare earth element ion and one or more ions selected from Er < 3 + >, Pr < 3 + >, Ho < 3 + > or Tm < 3 + > as a second rare earth element ion. The upconversion material prepared by the invention has high efficiency and stability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of solar cells, and particularly relates to an upconversion material, a preparation method thereof, an upconversion adhesive film and a solar cell. BACKGROUND

[0002] The wavelength range of sunlight irradiated to the ground surface is 200-2500 nm, and the energy level structure of silicon determines that it can only utilize the sunlight in the wavelength range of 400-1100 nm. Ultraviolet light with a wavelength shorter than 400 nm cannot be absorbed by silicon, but may damage the battery material, so the prior art usually converts the ultraviolet light into visible light through down-conversion technology for the battery. Although infrared light with a wavelength longer than 1100 nm has weak damage to the battery material, the energy contained in the infrared light accounts for more than 30% of the total energy of sunlight, and if not processed, a large amount of energy will be wasted, and the battery will be heated, thereby affecting the efficiency of the battery. Therefore, converting the infrared light into a wavelength range that can be utilized by the silicon battery through up-conversion technology is an important method for improving the efficiency of the solar cell.

[0003] The up-conversion technology is usually realized by using rare earth materials, and the rare earth materials used usually include erbium (Er), ytterbium (Yb), praseodymium (Pr), holmium (Ho), thulium (Tm) and the like. In the prior art, there are schemes of directly printing the rare earth material on the back of the battery sheet (such as the patent document CN103346203A of Zhejiang Zhengtai Solar Energy Technology Co., Ltd. and the patent document CN101488533A of Beijing Jiaotong University), introducing the rare earth material into the adhesive film on the back (such as the patent document CN106566435A of Changzhou Sveck New Material Co., Ltd.), adding a new film layer containing the rare earth material (such as CN210110807U of Crystalline Energy Technology Co., Ltd.) and the like.

[0004] Although there are many reports on introducing the up-conversion material into the battery at present, few of them have both high efficiency and stability. On the one hand, the material collocation is not reasonable: the inorganic rare earth up-conversion material has poor compatibility with organic polymers, so the scheme of introducing the oxide or fluoride of the rare earth material into the adhesive film not only has low conversion efficiency, but also causes material agglomeration, affecting the transmittance; and the combination of the rare earth element with the ligand or perovskite all has stability problems. On the other hand, the material introduction position: the existing scheme usually introduces the up-conversion layer into the back of the battery, which may be to utilize the infrared light leaked by the battery sheet without blocking the sunlight from entering the battery. However, since the battery sheet has a certain thickness, many infrared lights will be scattered inside the battery sheet and finally converted into heat, which cannot be effectively utilized.

[0005] Therefore, it is urgent to develop an up-conversion material with both high efficiency and stability. SUMMARY

[0006] To solve the problems in the prior art, the application provides an upconversion material comprising rare earth element-inorganic matrix composite particles and a silane coupling agent coated on the surface of the rare earth element-inorganic matrix composite particles. The rare earth element of the application is composed of one or more of Yb 3+ , Er 3+ , Pr 3+ , Ho 3+ or Tm 3+ , which can not only occur in the upconversion process, but also in the quantum cutting process, and effectively utilize the various wave bands of sunlight. Secondly, the application selects an inorganic matrix to avoid the introduction of relatively unstable organic ligands or perovskites, and the selected matrix has the characteristics of strong ultraviolet absorption, high visible light transmittance, low phonon energy and high chemical stability, so that the upconversion material can improve the utilization efficiency of ultraviolet light and infrared light without affecting the absorption of the battery itself, and reduce the damage of ultraviolet light and heat accumulation to the battery. Finally, the application selects a silane coupling agent to coat on the surface of the rare earth element-inorganic matrix composite particles, which can not only make the upconversion material more uniformly dispersed in the upconversion adhesive film, but also avoid the agglomeration between the upconversion materials, so as to realize a uniform and transparent upconversion adhesive film. The upconversion adhesive film of the application has high transparency, so it can be directly placed on the front of the battery, and the material can directly absorb sunlight without scattering through the battery, which improves the sunlight conversion efficiency while reducing the heat accumulation of the battery. In summary, the upconversion material prepared by the application has high efficiency and stability.

[0007] Specifically, the application provides an upconversion material comprising rare earth element-inorganic matrix composite particles and a surface modifier coated on the surface of the rare earth element-inorganic matrix composite particles; the surface modifier is a silane coupling agent and / or polyethylene glycol; the rare earth element-inorganic matrix composite particles comprise an inorganic matrix and rare earth element ions; the inorganic matrix is selected from one or more of SrF2, BaF2, NaYF4, NaLaF4, NaY(WO4)2, KY(WO4)2, TiO2, Y2O3, YVO4 and LaVO4; the rare earth element ions are composed of Yb 3+ as a first rare earth element ion and one or more ions selected from Er 3+ , Pr 3+ , Ho 3+ or Tm 3+ as a second rare earth element ion.

[0008]

[0009] In one or more embodiments, the molar ratio of Yb 3+ to the inorganic matrix in the rare earth element-inorganic matrix composite particles is (0.5-50):100, for example (1-50):100.​

[0010] In one or more embodiments, the molar ratio of the second rare earth element ion to the inorganic matrix in the rare earth element-inorganic matrix composite particle is (0.1-10): 100, for example (0.1-5): 100.

[0011] In one or more embodiments, the silane coupling agent is selected from one or more of 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3- aminopropyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 2-(3,4- epoxycyclohexyl)ethyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3- methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, and 3- isocyanatopropyltriethoxysilane.

[0012] In one or more embodiments, the mass ratio of the rare earth element-inorganic matrix composite particle to the surface modifier is (5-20): 1.

[0013] The present application provides a method for preparing the up-conversion material of claim 1 or 2,

[0014] When the inorganic matrix contains oxygen atoms, the method comprises the following steps:

[0015] (1) mixing a salt containing rare earth element ions, a salt containing inorganic matrix cations, a salt containing inorganic matrix anions, and a solvent, then adding a chelating agent and stirring, and finally adding ethylene glycol and reacting, after the reaction is completed, washing, drying, and calcining to obtain rare earth element-inorganic matrix composite particles;

[0016] (2) dispersing the rare earth element-inorganic matrix composite particles obtained in step (1) in a solvent, reacting with a surface modifier, centrifuging, washing, and drying to obtain an up-conversion material;

[0017] Alternatively, when the inorganic matrix contains halogen atoms, the method comprises the following steps:

[0018] (1') mixing a salt containing rare earth element ions, a salt containing inorganic matrix cations, and a solvent to obtain a mixed solution A, mixing a salt containing inorganic matrix anions and a solvent to obtain a mixed solution B, mixing the mixed solution B and the mixed solution A, then reacting, after the reaction is completed, washing, drying, and calcining to obtain rare earth element-inorganic matrix composite particles;

[0019] (2') dispersing the rare earth element-inorganic matrix composite particles obtained in step (1') in a solvent, reacting with a surface modifier, centrifuging, washing, and drying to obtain an up-conversion material.

[0020] In one or more embodiments, in step (1), the salt containing rare earth element ions is a nitrate salt.

[0021] In one or more embodiments, in step (1), the chelating agent is citric acid.

[0022] In one or more embodiments, in step (1), the ratio of the molar amount of the chelating agent to the total molar amount of rare earth elements in the system is (1-6): 1.

[0023] In one or more embodiments, in step (1), the ratio of the molar amount of ethylene glycol to the total molar amount of rare earth elements in the system is (2-10): 1.

[0024] In one or more embodiments, in step (1), the reaction temperature is 150-200°C.

[0025] In one or more embodiments, in step (1), the reaction time is 8-16h.

[0026] In one or more embodiments, in step (1), washing with water and / or ethanol is performed.

[0027] In one or more embodiments, in step (1), the calcination is performed under a nitrogen atmosphere.

[0028] In one or more embodiments, in step (1), the calcination temperature is 800-1200°C.

[0029] In one or more embodiments, in step (1), the calcination time is 2-6h.

[0030] In one or more embodiments, in step (1'), the salt containing rare earth element ions is a nitrate salt.

[0031] In one or more embodiments, in step (1'), the solvent is ethylene glycol.

[0032] In one or more embodiments, in step (1'), the reaction temperature is 180-200°C.

[0033] In one or more embodiments, in step (1'), the reaction time is 6-12h.

[0034] In one or more embodiments, in step (1'), washing with water and / or ethanol is performed.

[0035] In one or more embodiments, in step (1'), the calcination is performed under an ammonium fluoride atmosphere.

[0036] In one or more embodiments, in step (1'), the calcination temperature is 800-1200°C.

[0037] In one or more embodiments, in step (1'), the calcination time is 2-6h.

[0038] In one or more embodiments, in step (2) and step (2'), the solvent is ethanol.

[0039] In one or more embodiments, in step (2) and step (2'), the reaction temperature is 40-80℃.

[0040] In one or more embodiments, in step (2) and step (2'), the reaction time is 4-8h.

[0041] In one or more embodiments, in step (2) and step (2'), ethanol is used for washing.

[0042] The present application provides an upconversion adhesive film, which comprises 0.01wt%-2wt% of the upconversion material described in the present application, 93wt%-99.49wt% of a polymer substrate, and 0.1wt%-5wt% of an auxiliary agent; preferably, the auxiliary agent comprises one or more selected from a silane coupling agent, an antioxidant, and a crosslinking agent; more preferably, the auxiliary agent comprises an antioxidant and a crosslinking agent.

[0043] In one or more embodiments, the polymer substrate is selected from one or more of polyethylene terephthalate, polyvinyl butyral, ethylene-vinyl acetate copolymer, polyethylene, ethylene polytetrafluoroethylene, polyimide, polycarbonate, polystyrene, polyurethane, polyacrylate, silicone sol-gel, and polyolefin elastomer.

[0044] In one or more embodiments, the polymer substrate has a refractive index of 1.4-1.7.

[0045] In one or more embodiments, the content of the antioxidant is 0.05wt%-2.5wt% based on the total mass of the upconversion adhesive film.

[0046] In one or more embodiments, the content of the crosslinking agent is 0.05wt%-2.5wt% based on the total mass of the upconversion adhesive film.

[0047] In one or more embodiments, the silane coupling agent is selected from one or more of 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3- aminopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2-(3,4- epoxycyclohexyl)ethyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3- methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3- isocyanatopropyltriethoxysilane.

[0048] In one or more embodiments, the antioxidant is selected from one or more of 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butylphenol, tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythrityl diphosphite, distearyl sulfide, and dilauryl sulfide.

[0049] In one or more embodiments, the crosslinking agent is selected from one or more of dicumyl peroxide, diisononyl peroxide, benzoyl peroxide, melamine, tert-butylperoxy benzoylformate, melamine cyanurate, and di-tert-butyl peroxide.

[0050] The present application provides a method for preparing the upconversion adhesive film, mixing the upconversion material, the polymer substrate and the auxiliary agent, heating to a molten state and extruding to obtain the upconversion adhesive film; preferably, the heating temperature is 60-100℃.

[0051] The present application provides a solar cell module, which comprises a solar cell piece and the upconversion adhesive film of the present application or the upconversion adhesive film prepared by the method of the present application, and the upconversion adhesive film is on the front surface of the solar cell piece; preferably, the solar cell module comprises one or more of the following devices: PN junction device containing III-V or II-IV group elements, Cu-In-Ga-Se thin film device, organic sensitizer device, organic thin film device, quantum dot thin film device, amorphous silicon solar cell, microcrystalline silicon solar cell and crystalline silicon solar device. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 The upconversion process schematic diagram of Er 3+ -Yb 3+ The upconversion process schematic diagram of Er

[0053] Figure 2 The upconversion process schematic diagram of Er 3+ -Yb 3+ The quantum tailoring process schematic diagram of Er

[0054] Figure 3 Structure diagram of upconversion material in some embodiments of the present application. DETAILED DESCRIPTION

[0055] To enable persons skilled in the art to understand the features and effects of the present application, the following is a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific words used herein have the usual meanings to those skilled in the art of the present application, and in case of conflict, the definitions in the specification shall prevail.

[0056] Theories or mechanisms described and disclosed herein, whether correct or not, should not be considered limiting on the scope of the present application, that is, the present application can be practiced without regard to any particular theory or mechanism.

[0057] Herein, "comprising", "including", "containing", and like phrases, encompass "consisting essentially of" and "consisting of", for example, when it is disclosed herein that "A comprises B and C", "A consists essentially of B and C" and "A consists of B and C" should be considered to have been disclosed herein.

[0058] Herein, all features defined by numerical ranges or percentage ranges, such as values, amounts, contents and concentrations, are for the sake of brevity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have encompassed and specifically disclosed all possible sub-ranges and individual numerical values within the range (including

[0059] integers and fractions).

[0060] Herein, unless otherwise specified, percentages refer to mass percentages, and ratios refer to mass ratios.

[0061] Herein, when describing embodiments or examples, it should be understood that they are not intended to limit the present application to these embodiments or examples. Rather, all alternatives, modifications, equivalents, and equivalents of the methods and materials described herein are intended to be encompassed by the scope of the claims.

[0062] Herein, for the sake of brevity, all possible combinations of the technical features in each embodiment or example are not described. Therefore, as long as the combinations of the technical features do not contradict each other, the technical features in each embodiment or example can be combined in any manner, and all possible combinations should be considered to be within the scope of the present specification.

[0063] This invention provides an upconversion material comprising rare earth element-inorganic matrix composite particles and a surface modifier coated on the surface of the rare earth element-inorganic matrix composite particles; the surface modifier is a silane coupling agent and / or polyethylene glycol; the rare earth element-inorganic matrix composite particles contain an inorganic matrix and rare earth element ions.

[0064] In some implementation schemes, such as Figure 3 As shown, the upconversion material of the present invention includes rare earth element-inorganic matrix composite particles and a surface modifier coated on the surface of the rare earth element-inorganic matrix composite particles; the surface modifier is a silane coupling agent; the rare earth element-inorganic matrix composite particles contain an inorganic matrix and rare earth element ions.

[0065] In this invention, the rare earth element is preferably Yb, which serves as the first rare earth element ion. 3+ and as the second rare earth element ion selected from Er 3+ Pr 3+ Ho 3+ or Tm 3+ It consists of one or more ions. In this invention, the combination of rare earth element ions can not only undergo upconversion but also quantum trimming. In some embodiments, Yb 3+ and Er 3+ It is a combination of rare earth element ions, and the upconversion process involves multiple Er 3+ It absorbs 1550nm infrared light and reaches [the target area] through energy transfer. 4 F 9 / 2 or 4 I 9 / 2 The excited state is reached through vibrational relaxation. 4 I 11 / 2 The excited state then transfers energy to Yb. 3+ of 2 F 2 / 7 Ultimately Yb 3+ Emitting 976nm photons that silicon can absorb, such as Figure 1 As shown; quantum clipping is Er 3+ Absorb energy transfer to reach 4 G 11 / 2 Excited state, which relaxes to 2 H 11 / 2 Later, they successively sent two Yb 3+ Emit photons, and then Yb 3+ Emitting near-infrared photons, such as Figure 2 As shown. Therefore, by selecting the above combination of rare earth element ions, we can effectively utilize all wavelengths of sunlight and improve the efficiency of sunlight utilization.

[0066] In this invention, the inorganic matrix can be selected from SrF2, BaF2, NaYF4, NaLaF4, NaY(WO4)2, etc.

[0067] one or more of KY(WO4)2, TiO2, Y2O3, YVO4 and LaVO4. The inorganic oxide or halide matrix selected in the present application avoids the introduction of relatively unstable organic ligands or perovskites, and the selected matrix has the characteristics of strong absorption of ultraviolet light, high visible light transmittance, low phonon energy and high chemical stability, so that it can improve the utilization efficiency of the up-conversion material for ultraviolet light and infrared light while not affecting the absorption of the battery itself, and reduce the damage of ultraviolet light and heat accumulation to the battery.

[0068] In the present application, the molar ratio of Yb 3+ and the inorganic matrix can be (0.5-50):100, for example (1-50):100, and in some embodiments, the molar ratio of Yb 3+ and the inorganic matrix in the rare earth element-inorganic matrix composite particles is 2:100, 5:100, 10:100, 20:100, 30:100, 40:100, 50:100. The molar ratio of Yb 3+ and the inorganic matrix is controlled to be (1-50):100, which is beneficial to improve the utilization efficiency of sunlight.

[0069] In the present application, the molar ratio of the second rare earth element ion and the inorganic matrix in the rare earth element-inorganic matrix composite particles can be (0.1-10):100, for example (0.1-5):100, and in some embodiments, the molar ratio of the second rare earth element ion and the inorganic matrix in the rare earth element-inorganic matrix composite particles is 0.1:100, 0.5:100, 1:100, 2:100, 4:100, 6:100, 7:100, 8:100, 9:100, 10:100. The molar ratio of the second rare earth element ion and the inorganic matrix is controlled to be (0.1-5):100, which is beneficial to improve the utilization efficiency of sunlight.

[0070] In the present application, the silane coupling agent can be one or more selected from 3-aminopropyltriethoxysilane (APTES), 3-aminopropyltrimethoxysilane (APTMS), N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS), 3-glycidyloxypropyltrimethoxysilane (GPTMS), 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, vinyltrimethoxysilane (VTMS), vinyltriethoxysilane (VTES), 3-methacryloyloxypropyltrimethoxysilane (MEMO), 3-methacryloyloxypropyltriethoxysilane, and 3-isocyanatopropyltriethoxysilane (IPTS). Finally, the silane coupling agent is selected to coat the surface of the rare earth element-inorganic matrix composite particles in the present application, which can make the upconversion material more uniformly dispersed in the upconversion adhesive film, and avoid the agglomeration between the upconversion materials, so as to realize the uniform and transparent upconversion adhesive film. The upconversion adhesive film has high transparency, and can be directly placed on the front of the battery, so that the material can directly absorb sunlight without scattering through the battery, which improves the sunlight conversion efficiency and reduces the battery heat accumulation.

[0071] In the present application, the mass ratio of the rare earth element-inorganic matrix composite particles to the surface modifier is (5-20):1, for example, 5:1, 7:1, 9:1, 11:1, 13:1, 15:1, 17:1, or 20:1. Controlling the mass ratio of the rare earth element-inorganic matrix composite particles to the surface modifier in the above range is beneficial to avoid the agglomeration between the upconversion materials, improve the sunlight conversion efficiency, and reduce the battery heat accumulation.

[0072] The present application provides a method for preparing the upconversion material of the present application. When the inorganic matrix contains oxygen atoms, the method comprises the following steps:

[0073] (1) mixing a salt containing rare earth element ions, a salt containing inorganic matrix cations, a salt containing inorganic matrix anions, and a solvent, then adding a chelating agent and stirring, and finally adding ethylene glycol and reacting. After the reaction is completed, washing, drying, and calcining are performed to obtain rare earth element-inorganic matrix composite particles;

[0074] (2) dispersing the rare earth element-inorganic matrix composite particles prepared in step (1) in a solvent, reacting with a surface modifier, centrifuging, washing, and drying to obtain an upconversion material;

[0075] Alternatively, when the inorganic matrix contains halogen atoms, the method comprises the following steps:

[0076] (1') mixing a salt containing a rare earth element ion, a salt containing an inorganic matrix cation, and a solvent to obtain a mixed solution A, mixing a salt containing an inorganic matrix anion and a solvent to obtain a mixed solution B, mixing the mixed solution B and the mixed solution A, and then reacting, after the reaction, washing, drying, and calcining to produce a rare earth element-inorganic matrix composite particle;

[0077] (2') dispersing the rare earth element-inorganic matrix composite particle produced in step (1') in a solvent, reacting with a surface modifier, centrifuging, washing, and drying to produce an up-conversion material.

[0078] In step (1), the salt containing a rare earth element ion can be a nitrate.

[0079] In step (1), the chelating agent can be citric acid.

[0080] In step (1), the ratio of the molar amount of the chelating agent to the total molar amount of the rare earth elements in the system can be (1-6): 1, for example, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1.

[0081] In step (1), the ratio of the molar amount of the ethylene glycol to the total molar amount of the rare earth elements in the system can be (2-10): 1, for example, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1.

[0082] In step (1), the reaction temperature can be 150-200°C, for example, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C.

[0083] In step (1), the reaction time can be 8-16h, for example, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 16h.

[0084] In step (1), water and / or ethanol can be used for washing.

[0085] In step (1), the calcination can be performed under a nitrogen atmosphere.

[0086] In step (1), the calcination temperature can be 800-1200°C, for example, 800°C, 900°C, 1000°C, 1100°C, 1200°C.

[0087] In step (1), the calcination time can be 2-6h, for example, 2h, 3h, 4h, 5h, 6h.

[0088] In step (1'), the salt containing a rare earth element ion can be a nitrate.

[0089] In step (1'), the solvent can be ethylene glycol.

[0090] In step (1'), the reaction temperature can be 180-200℃, for example, 180℃, 185℃, 190℃, 195℃, 200℃.

[0091] In step (1'), the reaction time can be 6-12h, for example, 6h, 7h, 8h, 9h, 10h, 11h, 12h.

[0092] In step (1'), water and / or ethanol can be used for washing.

[0093] In step (1'), the calcination can be performed under an ammonium fluoride atmosphere.

[0094] In step (1'), the calcination temperature can be 800-1200℃, for example, 800℃, 900℃, 1000℃, 1100℃, 1200℃.

[0095] In step (1'), the calcination time can be 2-6h, for example, 2h, 3h, 4h, 5h, 6h.

[0096] In step (2) and step (2'), the solvent can be ethanol.

[0097] In step (2) and step (2'), the reaction temperature can be 40-80℃, for example, 40℃, 50℃, 60℃, 70℃, 80℃.

[0098] In step (2) and step (2'), the reaction time can be 4-8h, for example, 4h, 5h, 6h, 7h, 8h.

[0099] In step (2) and step (2'), ethanol can be used for washing.

[0100] The present application provides an upconversion adhesive film, which can comprise 0.01wt%-2wt% of the upconversion material of the present application, 93wt%-99.49wt% of a polymer substrate, and 0.1wt%-5wt% of an auxiliary agent. In the present application, the upconversion adhesive film comprising the upconversion material has both high efficiency and stability.

[0101] In the present application, the polymer substrate can be selected from polyethylene terephthalate, polyvinyl butyral, ethylene-vinyl acetate copolymer (EVA), polyethylene, ethylene polytetrafluoroethylene, polyimide, polycarbonate, polystyrene, polyurethane, polyacrylate, silicone sol-gel, and polyolefin

[0102] one or more of the hydrocarbon elastomers.

[0103] In the present application, the polymer substrate can have a refractive index of 1.4-1.7, for example 1.4, 1.5, 1.6, 1.7.

[0104] In the present application, the auxiliary agent comprises one or more selected from silane coupling agent, antioxidant and crosslinking agent; preferably, the auxiliary agent can comprise antioxidant and crosslinking agent. In the present application, the content of antioxidant can be 0.05wt%-2.5wt%, for example 0.05wt%, 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, based on the total mass of the upconversion adhesive film. In the present application, the content of crosslinking agent can be 0.05wt%-2.5wt%, for example 0.05wt%, 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, based on the total mass of the upconversion adhesive film.

[0105] In the present application, the silane coupling agent can be one or more selected from 3-aminopropyl triethoxysilane, 3-aminopropyl trimethoxysilane, N-2-(aminoethyl)-3-aminopropyl trimethoxysilane, 3-glycidyloxypropyl trimethoxysilane, 2-(3,4-epoxycyclohexyl) ethyl trimethoxysilane, vinyl trimethoxysilane, vinyl triethoxysilane, 3-methacryloxypropyl trimethoxysilane, 3-methacryloxypropyl triethoxysilane and 3-isocyanate propyl triethoxysilane.

[0106] In the present application, the antioxidant can be one or more selected from 2,6-di-tert-butyl-4-methylphenol (BHT), 2,6-di-tert-butylphenol (DBP), tris(2,4-di-tert-butylphenyl) phosphite (Irgafos 168), bis(2,4-di-tert-butylphenyl) glutaroyl pentamethyldiphosphite (Ultranox 626), distearyl sulfide (DSTDP) and dilauryl sulfide.

[0107] In the present application, the crosslinking agent can be one or more selected from dicumyl peroxide (DCP), diisononyl peroxide, benzoyl peroxide, melamine, tert-butyl peroxide benzene acid tert-butyl ester, melamine and di-tert-butyl peroxide.

[0108] The present application provides a method for preparing the upconversion adhesive film of the present application, mixing the upconversion material, the polymer substrate and the auxiliary agent, heating to a molten state and extruding to obtain the upconversion adhesive film.

[0109] In the process of preparing the upconversion adhesive film of the present application, the heating temperature can be 60-100℃, for example 60℃, 70℃, 80℃, 90℃, 100℃.

[0110] The application provides a solar cell module comprising a solar cell piece and an up-conversion adhesive film of the application, wherein the up-conversion adhesive film is on the front surface of the solar cell piece. The up-conversion adhesive film of the application has high transparency, can be directly placed on the front surface of the solar cell, and can directly absorb sunlight without scattering by the solar cell, thereby improving the sunlight conversion efficiency and reducing the heat accumulation of the solar cell, and the prepared solar cell module has high efficiency and stability.

[0111] In the application, the solar cell module comprises one or more of the following devices: a PN junction device containing III-V or II-IV elements, a Cu-In-Ga-Se (CIGS) thin film device, an organic sensitizer device, an organic thin film device, a quantum dot thin film device, an amorphous silicon solar cell, a microcrystalline silicon solar cell and a crystalline silicon solar device.

[0112] Compared with the prior art, the application has the following beneficial effects:

[0113] (1) The rare earth element-inorganic matrix composite particles in the up-conversion material of the application have quantum tailoring effect and up-conversion effect, and can realize efficient utilization of sunlight energy.

[0114] (2) The up-conversion adhesive film prepared in the application has high transparency, can be directly placed on the front surface of the solar cell, and can directly absorb sunlight without scattering by the solar cell, thereby improving the sunlight conversion efficiency and reducing the heat accumulation of the solar cell.

[0115] (3) The inorganic matrix of the up-conversion material of the application is chemically stable and has strong absorption of ultraviolet rays in sunlight, thereby avoiding damage of the ultraviolet rays to the solar cell and improving the service life of the solar cell.

[0116] The application will be described below in the form of specific examples. It should be understood that these examples are merely illustrative and are not intended to limit the scope of the application. The methods, reagents and materials used in the examples and test examples are conventional in the art unless otherwise specified, or are recommended by the instrument manufacturer. The raw material compounds in the examples can be purchased through commercial channels.

[0117] The solar cell in the examples and comparative examples of the application is a 182mm HJT solar cell of Huasheng New Energy Technology Co., Ltd.

[0118] Example 1

[0119] This example prepares a solar cell module according to the following steps:

[0120] (1) Preparation of rare earth element-inorganic matrix composite particles: dissolve sodium tungstate, yttrium nitrate, erbium nitrate and ytterbium nitrate in a molar ratio of 100:50:2:20 in deionized water, then add citric acid as a chelating agent according to a molar ratio of citric acid to rare earth metal (the molar amount of rare earth metal is the sum of the molar amounts of rare earth metals in yttrium nitrate, erbium nitrate and ytterbium nitrate) of 2:1, and stir until completely dissolved; then add ethylene glycol according to a molar ratio of ethylene glycol to rare earth metal of 4:1, stir uniformly, and obtain a mixed solution; transfer the mixed solution to a high-pressure reaction kettle, react at 180°C for 12h, cool to 25°C after the reaction is completed, and precipitate nanocrystals, then wash the precipitated nanocrystals with water and ethanol, and dry at 80°C; calcine the dried nanocrystals at 1000°C under a nitrogen atmosphere for 4h, and prepare NaY(WO4)2:Er:Yb nanocrystals, i.e. rare earth element-inorganic matrix composite particles;

[0121] (2) Preparation of upconversion material: disperse the NaY(WO4)2:Er:Yb nanocrystals in anhydrous ethanol, and ultrasonically disperse for 30min to obtain a NaY(WO4)2:Er:Yb nanocrystal solution; add APTES to the NaY(WO4)2:Er:Yb nanocrystal solution according to a mass ratio of NaY(WO4)2:Er:Yb nanocrystals to APTES of 10:1, stir uniformly, and react at 60°C for 6h to allow the APTES to fully react with the hydroxyl groups on the surface of the NaY(WO4)2:Er:Yb nanocrystals; after the reaction is completed, centrifugally separate, wash with anhydrous ethanol to remove unreacted APTES, and vacuum dry the reacted nanocrystals at 80°C for 4h to obtain the upconversion material;

[0122] (3) Preparation of upconversion adhesive film: uniformly mix 98.8wt% of EVA, 0.2wt% of upconversion material, 0.5wt% of BHT and 0.5wt% of DCP, melt and extrude at 80°C to obtain an upconversion adhesive film;

[0123] (4) Preparation of solar cell module: laminate the encapsulating glass, upconversion adhesive film, solar cell, pure EVA adhesive film and back plate under a negative pressure environment at 130°C, and naturally cool after the lamination is completed to obtain a solar cell module, wherein the upconversion adhesive film is on the front surface of the solar cell.

[0124] Example 2

[0125] This example prepares a solar cell module according to the following steps:

[0126] (1) Preparation of rare earth element-inorganic matrix composite particles: Yttrium nitrate, erbium nitrate, and ytterbium nitrate in a polytetrafluoroethylene beaker with a molar ratio of 100:2:20 were dissolved in ethylene glycol and mixed evenly to obtain solution A. Sodium fluoride was dissolved in ethylene glycol in a polytetrafluoroethylene beaker to obtain solution B. Solution B was slowly added dropwise to solution A with a molar ratio of sodium fluoride to yttrium nitrate of 4:1 and stirred continuously. The reaction was heated at 190℃ for 9 h. After the reaction was completed, the nanocrystals were separated by centrifugation and washed alternately with deionized water and anhydrous ethanol to remove surface residues. Then, the nanocrystals were vacuum dried at 80℃ for 4 h. The dried crystals were calcined at 1000℃ in an ammonium fluoride atmosphere for 4 h to obtain NaYF4:Er:Yb nanocrystals.

[0127] That is, rare earth element-inorganic matrix composite particles;

[0128] (2) Preparation of upconversion material: NaYF4:Er:Yb nanocrystals were dispersed in anhydrous ethanol and ultrasonically dispersed for 30 min to obtain NaYF4:Er:Yb nanocrystal solution; polyethylene glycol was added to the NaYF4:Er:Yb nanocrystal solution at a mass ratio of 10:1 to 2000 nanocrystals, stirred evenly, and reacted at 60℃ for 6 h. After the reaction was completed, the nanocrystals were centrifuged and washed with anhydrous ethanol to remove unreacted polyethylene glycol; the reacted nanocrystals were vacuum dried at 80℃ for 4 h to obtain upconversion material.

[0129] (3) Preparation of upconversion film: 98.8 wt% EVA, 0.2 wt% upconversion material, 0.5 wt% BHT and 0.5 wt% DCP are mixed evenly and melt-extruded at 80°C to obtain upconversion film;

[0130] (4) Preparation of solar cell module: Under a negative pressure environment at 130°C, the encapsulation glass, upconversion film, solar cell, pure EVA film and backsheet are laminated and naturally cooled after lamination to obtain solar cell module, wherein the upconversion film is on the front surface of the solar cell.

[0131] Example 3

[0132] The other conditions in this embodiment are the same as in embodiment 1, except that erbium nitrate in step (1) is replaced with an equimolar amount of praseodymium nitrate.

[0133] Example 4

[0134] The other conditions in this embodiment are the same as in embodiment 1, except that erbium nitrate in step (1) is replaced with an equimolar amount of thulium nitrate.

[0135] Example 5

[0136] The other conditions in this embodiment are the same as in embodiment 1, except that erbium nitrate in step (1) is replaced with an equimolar amount of holmium nitrate.

[0137] Comparative Example 1

[0138] The conditions for this comparative example are the same as those for Example 1, except that the following are not added in step (3):

[0139] The conversion material, the film formulation is: 99.0% wt ethylene-vinyl acetate (EVA), 0.5% wt BHT and 0.5% wt DCP.

[0140] Comparative Example 2

[0141] The other conditions for this comparative example are the same as those for Example 1, except that ytterbium nitrate is not added in step (1) of this comparative example.

[0142] Comparative Example 3

[0143] The other conditions of this comparative example are the same as those of Example 1, except that erbium nitrate is not added in step (1) of this comparative example.

[0144] Comparative Example 4

[0145] The other conditions of this comparative example are the same as those of Example 1, except that sodium tungstate and yttrium nitrate are not added in step (1) of this comparative example.

[0146] Comparative Example 5

[0147] The other conditions of this comparative example are the same as those of Example 1. The difference is that this comparative example does not include step (2), and the NaY(WO4)2:Er:Yb nanocrystals obtained in step (1) are directly used as the upconversion material in step (3).

[0148] Comparative Example 6

[0149] The other conditions of this comparative example are the same as those of Example 2. The difference is that this comparative example does not include step (2), and the NaYF4:Er:Yb nanocrystals obtained in step (1) are directly used as the upconversion material in step (3).

[0150] Test case

[0151] The upconversion films prepared in Examples 1-5 and Comparative Examples 1-6 were tested for transmittance and UV aging yellowing index. Solar cell modules containing the upconversion films prepared in Examples 1-5 and Comparative Examples 1-6 were tested for cell efficiency gain and cell efficiency degradation rate after UV aging. The test results are shown in Table 1.

[0152] Transmittance test: Measured using an Agilent Cary 3500 UV-Vis spectrophotometer.

[0153] Yellowness index test: UV aging was performed using a 142W multiplex UV aging chamber at 70°C for UV 120h aging, and the yellowness index was determined according to the national standard GB 2409 "Plastics - Determination of yellowness index".

[0154] Power test before and after UV aging: ANPA1000 tester from Shandong Aino Instrument Co., Ltd. was used for determination.

[0155] Table 1: Transmittance and UV aging yellowness index of upconversion adhesive films prepared in Examples 1-5 and Comparative Examples 1-6, and efficiency gain and decay rate of corresponding solar cells

[0156]

[0157] As can be seen from Table 1, the transmittance of the upconversion adhesive films added with upconversion materials in Examples 1, 3, 4 and 5 has little difference compared with the upconversion adhesive film without adding upconversion materials in Comparative Example 1. This is because the upconversion materials are modified by silane coupling agent surfactant before being introduced into the upconversion adhesive film, and the upconversion materials can be uniformly and stably dispersed in the upconversion adhesive film, so as not to significantly affect the transmittance.

[0158] Compared with the upconversion adhesive film without adding upconversion materials in Comparative Example 1, the transmittance of the upconversion adhesive film added with upconversion materials in Example 2 is slightly lower, which is because the matrix in Example 2 does not contain oxygen atoms, and the modification effect is poor, so the transmittance is slightly lower than that of other examples.

[0159] Compared with the upconversion adhesive film added with upconversion materials without surface modification by silane coupling agent in Comparative Example 5, the upconversion adhesive film added with upconversion materials modified by silane coupling agent in Example 1 has higher transmittance. This is because the material in Comparative Example 5 is not modified by silane coupling agent, and the material cannot be effectively dispersed in the upconversion adhesive film, which significantly affects the transmittance of the adhesive film and the improvement of the device efficiency and service life. Similarly, the non-addition of polyethylene glycol in Comparative Example 6 also causes the material to be unable to be effectively dispersed in the upconversion adhesive film, resulting in a decrease in transmittance and other properties. In summary, the modification of silane coupling agent or the addition of polyethylene glycol enables the upconversion materials to be more uniformly dispersed in the upconversion adhesive film, avoiding the agglomeration of the upconversion materials, thereby preparing a uniform and transparent upconversion adhesive film. The upconversion adhesive film with high transparency can be directly placed on the front of the battery, and the material can directly absorb sunlight without passing through the scattering of the solar cell, thereby improving the sunlight conversion efficiency and reducing the heat accumulation of the solar cell.

[0160] As shown in Table 1, compared with the up-conversion material without inorganic matrix prepared in Comparative Example 4, the up-conversion material with inorganic matrix prepared in Example 1 has a significantly smaller yellowing index of the corresponding up-conversion film and a smaller efficiency decay of the solar cell device after UV aging. This is because the rare earth material itself cannot effectively absorb sunlight, which further illustrates that the inorganic matrix selected in the application has a strong absorption of ultraviolet light below 400 nm, which does not affect the absorption of the battery itself, improves the utilization efficiency of the up-conversion material for ultraviolet and infrared light, and reduces the damage of ultraviolet light and heat accumulation to the battery.

[0161] As shown in Table 1, compared with the up-conversion material without adding Yb 3+ prepared in Comparative Example 2, the device efficiency of the up-conversion material with Yb 3+ prepared in Example 1 has a more obvious improvement. This is because without adding Yb 3+ , the system can only convert ultraviolet light into visible light, and cannot occur quantum cutting process and up-conversion process, so the efficiency improvement is very small. Compared with the up-conversion material without adding Er 3+ prepared in Comparative Example 3, the device efficiency of the up-conversion material with Er 3+ prepared in Example 1 has a more obvious improvement. This is because without adding Er 3+ , Yb 3+ cannot convert light, and cannot occur quantum cutting process and up-conversion process, so the efficiency has almost no improvement. Further illustrates that the combination of rare earth elements in the application can not only occur up-conversion process, but also occur quantum cutting process. It can effectively utilize each band of sunlight to improve the utilization efficiency of sunlight.

Claims

1. An upconversion material, characterized in that, The up-conversion material comprises rare earth element-inorganic matrix composite particles and a surface modifier coated on the surface of the rare earth element-inorganic matrix composite particles; The surface modifier is a silane coupling agent and / or polyethylene glycol; The rare earth element-inorganic matrix composite particles comprise an inorganic matrix and rare earth element ions; The inorganic matrix is selected from one or more of SrF2, BaF2, NaYF4, NaLaF4, NaY(WO4)2, KY(WO4)2, TiO2, Y2O3, YVO4, and LaVO4; The rare earth element ions consist of Yb as a first rare earth element ion 3+ and ions of one or more selected from the group consisting of Er 3+ , Pr 3+ , Ho 3+ or Tm 3+ as a second rare earth element ion.

2. The upconversion material of claim 1, wherein, The up-conversion material has one or more of the following characteristics: The rare earth element-inorganic matrix composite particles contain Yb 3+ The molar ratio of the inorganic matrix to the inorganic matrix is ​​(0.5-50):100, for example (1-50):100; The molar ratio of the second rare earth element ions to the inorganic matrix in the rare earth element-inorganic matrix composite particles is (0.1-10):100, for example (0.1-5):100; The silane coupling agent is selected from one or more of 3-aminopropyl triethoxysilane, 3-aminopropyl trimethoxysilane, N-2-(aminoethyl)-3-aminopropyl trimethoxysilane, 3-glycidyloxypropyl trimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, vinyl trimethoxysilane, vinyl triethoxysilane, 3-methacryloyloxypropyl trimethoxysilane, 3-methacryloyloxypropyl triethoxysilane, and 3-isocyanatopropyl triethoxysilane; The mass ratio of the rare earth element-inorganic matrix composite particles to the surface modifier is (5-20):

1.

3. A method for preparing the up-conversion material of claim 1 or 2, characterized in that, When the inorganic matrix contains oxygen atoms, the method comprises the following steps: (1) mixing a salt containing rare earth element ions, a salt containing inorganic matrix cations, a salt containing inorganic matrix anions, and a solvent, then adding a chelating agent and stirring, and finally adding ethylene glycol and reacting, after the reaction is completed, washing, drying, and calcining to obtain rare earth element-inorganic matrix composite particles; (2) dispersing the rare earth element-inorganic matrix composite particles obtained in step (1) in a solvent, reacting with a surface modifier, centrifuging, washing, and drying to obtain the up-conversion material; Alternatively, when the inorganic matrix contains halogen atoms, the method comprises the following steps: (1') mixing a salt containing rare earth element ions, a salt containing inorganic matrix cations, and a solvent to obtain mixed solution A, mixing a salt containing inorganic matrix anions and a solvent to obtain mixed solution B, mixing mixed solution B and mixed solution A, and then reacting, after the reaction is completed, washing, drying, and calcining to obtain rare earth element-inorganic matrix composite particles; (2') dispersing the rare earth element-inorganic matrix composite particles obtained in step (1') in a solvent, reacting with a surface modifier, centrifuging, washing, and drying to obtain the up-conversion material. The method has one or more of the following characteristics:

4. The method of claim 3, wherein, In step (1), the salt containing rare earth element ions is a nitrate salt; In step (1), the chelating agent is citric acid; In step (1), the ratio of the molar amount of the chelating agent to the total molar amount of rare earth elements in the system is (1-6):1; ​ In step (1), the ratio of the molar amount of ethylene glycol to the total molar amount of rare earth elements in the system is (2-10):1; In step (1), the reaction temperature is 150-200℃; In step (1), the reaction time is 8-16h; In step (1), washing with water and / or ethanol is used; In step (1), the calcination is performed under a nitrogen atmosphere; In step (1), the calcination temperature is 800-1200℃; In step (1), the calcination time is 2-6h.

5. The method of claim 3, wherein, The method has one or more of the following features: In step (1'), the salt containing rare earth element ions is a nitrate salt; In step (1'), the solvent is ethylene glycol; In step (1'), the reaction temperature is 180-200℃; In step (1'), the reaction time is 6-12h; In step (1'), washing with water and / or ethanol is used; In step (1'), the calcination is performed under an ammonium fluoride atmosphere; In step (1'), the calcination temperature is 800-1200℃; In step (1'), the calcination time is 2-6h.

6. The method of claim 3, wherein, The method has one or more of the following features: In step (2) and step (2'), the solvent is ethanol; In step (2) and step (2'), the reaction temperature is 40-80℃; In step (2) and step (2'), the reaction time is 4-8h; In step (2) and step (2'), washing with ethanol is used.

7. An upconversion film, characterized in that, The upconversion adhesive film comprises 0.01wt%-2wt% of the upconversion material according to claim 1 or 2, 93wt%-99.49wt% of a polymer substrate, and 0.1wt%-5wt% of an auxiliary agent; preferably, the auxiliary agent comprises one or more selected from silane coupling agents, antioxidants, and crosslinking agents; more preferably, the auxiliary agent comprises an antioxidant and a crosslinking agent.

8. The upconversion glue film of claim 7, wherein, The upconversion adhesive film has one or more of the following features: The polymer substrate is selected from one or more of polyethylene terephthalate, polyvinyl butyral, ethylene-vinyl acetate copolymer, polyethylene, ethylene polytetrafluoroethylene, polyimide, polycarbonate, polystyrene, polyurethane, polyacrylate, silicone sol-gel, and polyolefin elastomer; The refractive index of the polymer substrate is 1.4-1.7; The content of the antioxidant is 0.05wt%-2.5wt% based on the total mass of the upconversion adhesive film; The content of the crosslinking agent is 0.05wt%-2.5wt% based on the total mass of the upconversion adhesive film; The silane coupling agent is selected from one or more of 3-aminopropyl triethoxysilane, 3-aminopropyl trimethoxysilane, N-2-(aminoethyl)-3-aminopropyl trimethoxysilane, 3-glycidyloxypropyl trimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, vinyl trimethoxysilane, vinyl triethoxysilane, 3-methacryloyloxypropyl trimethoxysilane, 3-methacryloyloxypropyl triethoxysilane, and 3-isocyanatopropyl triethoxysilane; The antioxidant is selected from one or more of 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butylphenol, tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) glutaroyl pentamethyl diphosphate, distearyl sulfide, and dilauryl sulfide; The crosslinking agent is selected from one or more of dicumyl peroxide, diisononanoate peroxide, benzoyl peroxide, melamine, tert-butyl peroxybenzoate tert-butyl, melamine cyanurate, and di-tert-butyl peroxide.

9. A method of preparing the up-conversion glue film according to claim 7 or 8, characterized in that, The upconversion material, the polymer base material and the auxiliary agent are mixed and extruded in a molten state by heating to obtain the upconversion adhesive film; preferably, the heating temperature is 60-100℃.

10. A solar cell module characterized by comprising: The solar cell module comprises a solar cell piece and the upconversion adhesive film of claim 7 or 8 or the upconversion adhesive film prepared by the method of claim 9, and the upconversion adhesive film is on the front surface of the solar cell piece; Preferably, the solar cell module comprises one or more of the following devices: PN junction device containing III-V or II-IV group elements, Cu-In-Ga-Se thin film device, organic sensitizer device, organic thin film device, quantum dot thin film device, amorphous silicon solar cell, microcrystalline silicon solar cell and crystalline silicon solar device.

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