A red fluorescent material, a preparation method and application thereof, and an energy down-conversion film and a preparation thereof

Abstract

The application provides a red fluorescent material, a preparation method and application thereof, and an energy down-conversion film and a preparation thereof, and belongs to the technical field of luminescent materials. 1‑x Mg 1‑y Al 10‑z O 17 :xEu 2+ ,yMn 2+ ,zCr 3+ ; wherein, 0

Description

Technical Field

[0001] This invention relates to the field of luminescent materials technology, and in particular to a red fluorescent material, its preparation method and application, and an energy down-conversion thin film and its preparation. Background Technology

[0002] Among commonly available renewable energy sources, solar energy stands out from other clean energy sources such as ocean energy, wind energy, geothermal energy, and bioenergy due to its abundant sources, unlimited "storage capacity," environmental friendliness, and ease of clean utilization. In recent years, solar energy has become a top priority in the development of clean energy due to its unparalleled advantages, and is gradually becoming active in various fields of energy utilization.

[0003] Solar cells are the most common device for utilizing solar energy, converting sunlight into electricity for human production and daily life through the photovoltaic effect. They represent a long-term sustainable energy production method with numerous advantages, including being green and low-carbon. Although crystalline silicon solar cell technology is currently very mature, the maximum photoelectric conversion efficiency of existing crystalline silicon solar cells on the market is only 26%. Fundamentally, the low photoelectric conversion efficiency of silicon solar cells is due to their poor response to the solar spectrum and the short penetration depth of short-wavelength photons in silicon. Silicon has a bandgap of approximately 1.1 eV, corresponding to a wavelength of 1100 nm. Therefore, photons with energy less than the bandgap (wavelength > 1100 nm) cannot generate charge carriers, while photons with wavelengths much smaller than 1100 nm have energy much greater than 1.1 eV, and this excess energy is dissipated as heat, resulting in energy waste. Therefore, silicon solar cells have a better spectral response in the red to near-infrared range (600 nm–1100 nm) but a weaker spectral response in the 200 nm–600 nm range, exhibiting a spectral mismatch problem.

[0004] To address the spectral mismatch problem in solar cells, researchers have discovered that the spectral conversion effect can effectively utilize the solar spectrum. This involves converting poorly absorbed wavelengths of light from silicon-based solar cells into effectively absorbed wavelengths, thereby improving the spectral utilization rate of the solar cells. In most existing studies, one method for applying phosphors to solar cells is to directly coat the surface of silicon-based solar cells using a spin-coating method. However, this method is limited by problems such as unstable phosphor-solar cell bonding efficiency, low improvement in solar cell photoelectric conversion efficiency, low light source energy utilization efficiency, and unsuitability for large-scale industrial production. Another application method is to mix phosphors with copolymers to create a down-transfer film (CN113078223A). While this method allows for more direct application to the solar cell surface and better overcomes the lower spectral response in the short-wavelength region, its biggest drawback is that short-wavelength light is more easily reflected, with a significant portion of short-wavelength photons being reflected into the air without being absorbed by the cell, resulting in a lower photoelectric conversion rate. Summary of the Invention

[0005] The purpose of this invention is to provide a red fluorescent material, its preparation method and application, and an energy down-conversion film and its preparation. The red fluorescent material can be excited by ultraviolet or blue light in sunlight to emit near-red or red light. The EDC film prepared using this red fluorescent material improves the utilization rate of sunlight by converting ultraviolet or blue light in sunlight into near-red or red light that is easily absorbed by the solar cell, thereby improving the photoelectric conversion efficiency.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a red fluorescent material with the chemical composition Ba. 1-x Mg 1-y Al 10-z O 17 :xEu 2+ ,yMn 2+ ,zCr 3 + ; among which, 0 <x≤0.5,0<y≤0.5,0<z≤0.05。

[0008] Preferably, x = 0.3, y = 0.3 and z = 0.03.

[0009] This invention provides a method for preparing the red fluorescent material described in the above technical solution, comprising the following steps:

[0010] Ba source, Mg source, Al source, Eu source, Mn source, Cr source and flux were ground and mixed. The resulting mixture was sintered in a reducing atmosphere and the surface sample was removed to obtain a red fluorescent material.

[0011] Preferably, the Ba source includes BaO, BaCO3, Ba(OH)2·8H2O, Ba(NO3)2, BaSO4, or BaCl2;

[0012] The Mg source includes MgO, MgCO3, Mg(OH)2, Mg(NO3)2·6H2O or MgCl2;

[0013] The Al source includes Al2O3, Al(OH)3, AlOOH, Al(NO3)3·9H2O, Al2(SO4)3 or AlCl3;

[0014] The Eu source includes Eu2O3, Eu2(SO4)3, Eu(NO3)3·6H2O, EuCl2, EuCl3 or EuF3;

[0015] The Mn source includes MnO, MnO2, Mn2O3, Mn3O4, MnCO3, Mg(OH)2, Mn(NO3)2·6H2O or MnCl2·4H2O;

[0016] The Cr source includes Cr2O3, Cr(NO3)3·9H2O, CrCl2·6H2O or CrF3;

[0017] The flux includes AlF3, KF, LiF, NaF, BaF2, NH4Cl or H3BO3.

[0018] Preferably, the mass of the flux is 0 to 7 wt% of the total mass of the Ba source, Mg source, Al source, Eu source, Mn source and Cr source, and is not 0; the reducing atmosphere is a N2+H2 mixed atmosphere, and the volume ratio of N2 to H2 is 9:1; the sintering temperature is 1450 to 1600°C, and the time is 2 to 6 hours.

[0019] This invention provides the application of the red fluorescent material described in the above technical solution or the red fluorescent material prepared by the preparation method described in the above technical solution in solar cells.

[0020] This invention provides a method for preparing an energy down-conversion thin film, comprising the following steps:

[0021] An organic polymer is mixed with an organic solvent, and the resulting colloidal polymer is then mixed with a red fluorescent material to obtain a powder mixture; the red fluorescent material is the red fluorescent material described in the above technical solution or the red fluorescent material prepared by the preparation method described in the above technical solution.

[0022] Coat the powder mixture on the surface of the solar cell and dry it to obtain an energy down-conversion thin film.

[0023] Preferably, the organic polymer includes ethylene-vinyl acetate copolymer, polyvinylpyrrolidone, ethylene-octene copolymer or epoxy resin.

[0024] Preferably, the dosage ratio of the organic polymer to the organic solvent is 3 g:10 mL to 1 g:20 mL; the mass ratio of the red fluorescent material to the colloidal polymer is 1:10 to 100.

[0025] The present invention provides an energy down-conversion thin film prepared by the preparation method described in the above technical solution.

[0026] The present invention provides a red fluorescent material with a chemical composition of Ba 1-x Mg 1-y Al 10-z O 17 :xEu 2+ ,yMn 2+ ,zCr 3 + ; wherein, 0 < x ≤ 0.5, 0 < y ≤ 0.5, 0 < z ≤ 0.05. This red fluorescent material contains Eu 2+ ,Mn 2+ ,Cr 3+ triple activators, where Eu 2+ is a parity and spin-allowed transition, and the emission is located at 400 - 500 nm; Mn 2+ is a parity and spin-forbidden transition, and the emission is located at 480 - 560 nm; Cr 3+ is a parity-forbidden transition, and there may also be a spin-forbidden transition or a spin-allowed transition, and the emission is located at 650 - 750 nm. The present invention incorporates three activator ions into the BaMgAl 10 O 17 matrix. The multiple energy transfers between Eu 2+ -Mn 2+ -Cr 3+ ions can not only effectively enhance the emission intensity of each ion, thereby enhancing the emission intensity of BaMgAl 10 O 17 , but also greatly broaden the spectral range. Therefore, the excitation spectrum of this red fluorescent material covers a wide area and can be excited by ultraviolet light or blue light in sunlight to emit near-red light or red light, directly converting ultraviolet light with a wavelength of 300 - 400 nm into red light with a wavelength of 650 - 750 nm (corresponding to the optimal response wavelength region of the solar cell), thereby improving the spectral mismatch problem of the solar cell, enhancing the light utilization rate of the solar cell, and increasing the photoelectric conversion efficiency of the solar device.

[0027] The red fluorescent material described in this invention is prepared by high-temperature solid-state method combined with sintering in a reducing atmosphere. The preparation method of this invention is simple and easy to operate, and does not produce harmful substances. It is green, environmentally friendly, and pollution-free, with low cost, and can stably improve the solar energy utilization rate of silicon-based solar cells, thus having broad application prospects.

[0028] This invention introduces a red fluorescent material into an organic polymer as a light-converting agent and coats it onto the surface of a solar cell to prepare an energy down-conversion film. This achieves synergistic coupling between the organic polymer light conversion film and the solar cell. The prepared energy down-conversion film enhances the absorption capacity of the solar cell spectrum by effectively converting ultraviolet or blue light with poor photoelectric response in sunlight into near-red or red light that is easily absorbed by the silicon-based solar cell. This effectively enhances the absorption efficiency of the solar cell in the near-ultraviolet region, improves the utilization rate of sunlight, and thus improves the photoelectric conversion efficiency, achieving effective coupling. Therefore, the red fluorescent material of this invention has high quantum efficiency, which can overcome the problem of low conversion rate caused by mixing phosphors with copolymers to prepare spectral down-conversion films.

[0029] The red fluorescent material of this invention has a high degree of matching with the solar spectrum, which can better achieve spectral response with solar cells. When the energy down-conversion film prepared from this fluorescent material is effectively coupled with the silicon-based solar cell, the silicon-based solar cell can absorb more red light, thereby maximizing the utilization of solar energy and improving the photoelectric conversion efficiency of the solar cell.

[0030] Furthermore, the present invention uses EVA organic polymer to prepare energy down-conversion thin films, which not only have good light transmittance and do not physically obstruct sunlight, but also have high adhesion properties and are not prone to peeling, thus enabling large-scale applications. Attached Figure Description

[0031] Figure 1 Ba in Example 1 0.7 Mg 0.7 Al 9.97 O 17 0.3Eu 2+ 0.3Mn 2+ 0.03Cr 3+ XRD pattern of phosphor;

[0032] Figure 2 Ba in Example 1 0.7 Mg 0.7 Al 9.97 O 17 0.3Eu 2+ 0.3Mn 2+ 0.03Cr3+ EDS spectrum of phosphor;

[0033] Figure 3 Ba in Example 1 0.7 Mg 0.7 Al 9.97 O 17 0.3Eu 2+ 0.3Mn 2+ 0.03Cr 3+ Excitation and emission spectra of phosphors;

[0034] Figure 4 Ba in Example 1 0.7 Mg 0.7 Al 9.97 O 17 0.3Eu 2+ 0.3Mn 2+ 0.03Cr 3+ Quantum efficiency graph of phosphor;

[0035] Figure 5 Ba in Example 1 0.7 Mg 0.7 Al 9.97 O 17 0.3Eu 2+ 0.3Mn 2+ 0.03Cr 3+ Particle size distribution diagram of phosphor;

[0036] Figure 6 This is a comparison graph showing the luminescence intensity of the phosphors obtained in Example 1 and Comparative Example 1.

[0037] Figure 7 This is a schematic diagram of a model combining a silicon solar cell with a phosphor-energy down-conversion thin film.

[0038] Figure 8 This is a comparison of the IV curves of the silicon-based solar cell with BAM-EVA light conversion film coating and the bare solar cell in Example 1.

[0039] Figure 9 The graph shows the quantum efficiency curves of the silicon-based solar cell with BAM-EVA light-conversion film coating and the bare solar cell in Example 1.

[0040] Figure 10 The graph shows a comparison of the luminescence intensity of the phosphors prepared in Examples 1, 6-10. Detailed Implementation

[0041] This invention provides a red fluorescent material with the chemical composition Ba. 1-x Mg 1-yAl 10-z O 17 : xEu 2+ , yMn 2+ , zCr 3 + ; wherein, 0 < x ≤ 0.5, 0 < y ≤ 0.5, 0 < z ≤ 0.05.

[0042] In the present invention, x, y, and z are the molar percentages of Eu 2+ , Mn 2+ [[ID=1۸]]and Cr 3+ relative to the substituted atoms.

[0043] In the present invention, preferably 0.1 < x ≤ 0.4, more preferably 0.2 < x ≤ 0.35; preferably 0.1 < y ≤ 0.4, more preferably 0.2 < y ≤ 0.35; preferably 0.01 < z ≤ 0.04, more preferably 0.02 < z ≤ 0.03.

[0044] As a preferred embodiment of the present invention, x = 0.3, y = 0.3 and z = 0.03, corresponding to the chemical composition of the red fluorescent material being Ba 0.7 Mg 0.7 Al 9.97 O 17 : 0.3Eu 2+ , 0.3Mn 2+ , 0.03Cr 3+ .

[0045] The present invention provides a preparation method for the red fluorescent material described in the above technical solution, comprising the following steps:

[0046] Grind and mix the Ba source, Mg source, Al source, Eu source, Mn source, Cr source and flux, sinter the obtained mixed material in a reducing atmosphere, and then remove the surface sample to obtain the red fluorescent material.

[0047] In the present invention, unless otherwise specified, the raw materials required for preparation are all commercially available products well-known to those skilled in the art.

[0048] In the present invention, the Ba source preferably includes BaO, BaCO3, Ba(OH)2·8H2O, Ba(NO3)2, BaSO4 or BaCl2.

[0049] In the present invention, the Mg source preferably includes MgO, MgCO3, Mg(OH)2, Mg(NO3)2·6H2O or MgCl2.

[0050] In the present invention, the Al source preferably includes Al2O3, Al(OH)3, AlOOH, Al(NO3)3·9H2O, Al2(SO4)3 or AlCl3.

[0051] In this invention, the Eu source preferably includes Eu2O3, Eu2(SO4)3, Eu(NO3)3·6H2O, EuCl2, EuCl3 or EuF3.

[0052] In this invention, the Mn source preferably includes MnO, MnO2, Mn2O3, Mn3O4, MnCO3, Mg(OH)2, Mn(NO3)2·6H2O or MnCl2·4H2O.

[0053] In this invention, the Cr source preferably includes Cr2O3, Cr(NO3)3·9H2O, CrCl2·6H2O or CrF3.

[0054] The molar ratio of the Ba source, Mg source, Al source, Eu source, Mn source and Cr source described in this invention only needs to satisfy the chemical composition of the red fluorescent material.

[0055] In this invention, the flux preferably includes AlF3, KF, LiF, NaF, BaF2, NH4Cl or H3BO3, more preferably AlF3; the mass of the flux is preferably 0 to 7 wt% of the total mass of the Ba source, Mg source, Al source, Eu source, Mn source and Cr source and is not 0, more preferably 0.3 to 3 wt%.

[0056] In this invention, the Ba, Mg, Al, Eu, Mn, and Cr sources and flux are weighed according to their chemical composition. Anhydrous ethanol is added to an agate mortar for grinding, and then the mixture is placed in an alumina crucible. The alumina crucible is then placed in a high-temperature tube furnace for sintering. This invention does not have a specific limitation on the amount of anhydrous ethanol used; it can be adjusted according to requirements to ensure thorough grinding.

[0057] In this invention, the reducing atmosphere is preferably a N2+H2 mixed atmosphere, and the volume ratio of N2 to H2 is preferably 9:1.

[0058] In this invention, the sintering temperature is preferably 1450-1600℃, more preferably 1500-1550℃, and even more preferably 1525℃, and the sintering time is preferably 2-6h, more preferably 3-5h, and even more preferably 4h.

[0059] During the sintering process, some of the flux completely volatilizes, while the non-volatile flux remains on the surface of the sample after sintering. The flux can be removed by removing the surface sample without affecting the purity of the product.

[0060] After sintering, the present invention preferably removes the obtained product, grinds it again in a porcelain mortar, and dries it to obtain a red fluorescent material. The present invention does not have any particular limitations on the grinding and drying processes; they can be carried out according to procedures well known in the art.

[0061] This invention provides the application of the red fluorescent material described in the above technical solution or the red fluorescent material prepared by the preparation method described in the above technical solution in solar cells.

[0062] This invention provides a method for preparing an energy down-conversion thin film, comprising the following steps:

[0063] An organic polymer is mixed with an organic solvent, and the resulting colloidal polymer is then mixed with a red fluorescent material to obtain a powder mixture; the red fluorescent material is the red fluorescent material described in the above technical solution or the red fluorescent material prepared by the preparation method described in the above technical solution.

[0064] The adhesive powder mixture is coated onto the surface of a solar cell and dried to obtain an energy down-conversion film.

[0065] In this invention, the organic polymer includes ethylene-vinyl acetate copolymer (EVA), polyvinylpyrrolidone, ethylene-octene copolymer (POE), or epoxy resin. This invention does not impose any particular limitation on the source or type of the organic polymer; commercially available products well-known in the art are acceptable.

[0066] In this invention, the organic solvent is preferably toluene; the ratio of the organic polymer to the organic solvent is preferably 3g:10mL to 1g:20mL, more preferably 1g:4mL.

[0067] In this invention, the mass ratio of the red fluorescent material to the colloidal polymer is preferably 1:10 to 100, more preferably 1:15 to 80, and even more preferably 1:20 to 50.

[0068] In this invention, the colloidal polymer is mixed with a red fluorescent material and then stirred in a vacuum degassing machine for 5 minutes (stirring ensures that the red fluorescent material is evenly dispersed in the colloidal polymer, avoiding the presence of bubbles and segregation) to obtain a powder mixture. The powder mixture is then coated onto the surface of a solar cell using a spin coater at room temperature at a speed of 1200-2000 rpm / s (more preferably 1600 rpm / s) until the surface is smooth. The cell is then removed and allowed to air dry naturally to form a down-conversion thin film.

[0069] The present invention does not impose any special limitations on the solar cell described herein; any commercially available product known in the art is acceptable.

[0070] The present invention does not have a specific limitation on the coating method, and any method known in the art is acceptable, with spin coating being more preferred; the film thickness formed by the adhesive powder mixture on the surface of the solar cell is preferably 0.005 to 0.030 mm, more preferably 0.013 to 0.016 mm, which can avoid affecting the light transmittance or the phosphor failing to function.

[0071] The present invention provides an energy down-conversion thin film prepared by the preparation method described in the above technical solution.

[0072] Silicon-based solar cells generally exhibit weak photoelectric response in the ultraviolet range (300–400 nm), but strong photoelectric response in the visible to red light and near-infrared range (600–1100 nm). Energy down-conversion films can absorb ultraviolet or blue light and emit visible or near-infrared light that is favorable for absorption by silicon-based solar cells, while reducing scattered light, thereby improving their utilization of sunlight. Therefore, the energy down-conversion film of this invention transmits more red light, which is absorbed by the solar cell, thus improving the photoelectric conversion efficiency of the solar cell.

[0073] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0074] Example 1

[0075] Weigh out 0.1379g BaCO3, 0.0280g MgO, 0.5085g Al2O3, 0.0528g Eu2O3, 0.0345g MnCO3, 0.0023Cr2O3, and 0.0229g AlF3 according to the required chemical composition. Grind the mixture in an agate mortar with 5mL of anhydrous ethanol, then place the mortar into an alumina crucible. Place the alumina crucible in a high-temperature tube furnace and sinter for 4 hours at 1525℃ in a reducing atmosphere of N2+H2 (N2 to H2 volume ratio 9:1) to obtain BaCO3. 0.7 Mg 0.7 Al 9.97 O 17 0.3Eu 2+ 0.3Mn 2+ 0.03Cr 3+ Phosphor, i.e., z = 0.03;

[0076] According to the mass ratio of ethylene-vinyl acetate copolymer (EVA):phosphor of 15:1 and the volume ratio of ethylene-vinyl acetate copolymer (EVA):toluene of 1g:4mL, 2.5g of ethylene-vinyl acetate copolymer (EVA), 10.0mL of toluene, and 0.1667g of Ba were weighed out respectively. 0.7 Mg 0.7 Al 9.97 O17 0.3Eu 2+ 0.3Mn 2+ 0.03Cr 3+ Phosphor and EVA were placed in a vacuum degassing machine and stirred under vacuum for 5 minutes to obtain a paste mixture. At room temperature, the paste mixture was spin-coated onto the surface of a silicon-based solar cell (heterojunction HJT cell) at a speed of 1600 rpm / s using a spin coater. Figure 7 As shown in the figure, the battery is removed after the surface is smoothed and allowed to air dry naturally to form a silicon-based solar cell with a BAM-EVA energy down-conversion thin film coating.

[0077] Example 2

[0078] The only difference from Example 1 is that, according to the ethylene-vinyl acetate copolymer (EVA):phosphor mass ratio of 10:1, 2.5g of ethylene-vinyl acetate copolymer (EVA), 10.0mL of toluene, and 0.25g of Ba were weighed. 0.7 Mg 0.7 Al 9.97 O 17 0.3Eu 2+ 0.3Mn 2+ 0.03Cr 3+ Phosphor was used to prepare a silicon-based solar cell with a BAM-EVA energy down-conversion thin film coating, following the same spin-coating procedure as in Example 1.

[0079] Example 3

[0080] The only difference from Example 1 is that, according to the ethylene-vinyl acetate copolymer (EVA):phosphor mass ratio of 20:1, 2.5g of ethylene-vinyl acetate copolymer (EVA), 10.0mL of toluene, and 0.125g of Ba were weighed. 0.7 Mg 0.7 Al 9.97 O 17 0.3Eu 2 + 0.3Mn 2+ 0.03Cr 3+ Phosphor was used to prepare a silicon-based solar cell with a BAM-EVA energy down-conversion thin film coating, following the same spin-coating procedure as in Example 1.

[0081] Example 4

[0082] The only difference from Example 1 is that the same raw material ratio as in Example 1 is used, and the phosphor and EVA are placed in a vacuum degassing machine and stirred under vacuum for 5 minutes to obtain a gel powder mixture. The spin coating speed of the spin coater is changed, and the gel powder mixture is spin coated on the surface of the silicon-based solar cell at a rate of 1200 rpm / s to prepare a silicon-based solar cell with a BAM-EVA energy down-conversion thin film coating.

[0083] Example 5

[0084] The only difference from Example 1 is that the same raw material ratio as in Example 1 is used, and the phosphor and EVA are placed in a vacuum degassing machine and stirred under vacuum for 5 minutes to obtain a gel powder mixture. The spin coating speed of the spin coater is changed, and the gel powder mixture is spin coated on the surface of the silicon-based solar cell at a rate of 2000 rpm / s to prepare a silicon-based solar cell with a BAM-EVA energy down-conversion thin film coating.

[0085] Example 6

[0086] The only difference from Example 1 is that z = 0.001, resulting in Ba. 0.7 Mg 0.7 Al 9.97 O 17 0.3Eu 2+ 0.3Mn 2+ 0.001Cr 3+ The specific amounts of fluorescent powder raw materials are shown in Table 1.

[0087] Example 7

[0088] The only difference from Example 1 is that z = 0.005, resulting in Ba. 0.7 Mg 0.7 Al 9.97 O 17 0.3Eu 2+ 0.3Mn 2+ 0.005Cr 3+ The specific amounts of fluorescent powder raw materials are shown in Table 1.

[0089] Example 8

[0090] The only difference from Example 1 is that z = 0.01, resulting in Ba. 0.7 Mg 0.7 Al 9.97 O 17 0.3Eu 2+ 0.3Mn 2+ 0.01Cr 3+ The specific amounts of fluorescent powder raw materials are shown in Table 1.

[0091] Example 9

[0092] The only difference from Example 1 is that z = 0.02, resulting in Ba. 0.7 Mg 0.7 Al 9.97 O 17 0.3Eu 2+ 0.3Mn 2+ 0.02Cr 3+ The specific amounts of fluorescent powder raw materials are shown in Table 1.

[0093] Example 10

[0094] The only difference from Example 1 is that z = 0.05, resulting in Ba. 0.7 Mg 0.7 Al 9.97 O 17 0.3Eu 2+ 0.3Mn 2+ 0.05Cr 3+ The specific amounts of fluorescent powder raw materials are shown in Table 1.

[0095] The raw material usage for Examples 1, 6-10 is shown in Table 1.

[0096] Table 1. Raw material usage (g) for Examples 1, 6-10

[0097]

[0098]

[0099] Comparative Example 1

[0100] The only difference from Example 1 is that the flux AlF3 is not added, all other raw materials are weighed in the same mass as in Example 1, and sintering is carried out using the same sintering steps as in Example 1 to obtain Ba. 0.7 Mg 0.7 Al 9.97 O 17 0.3Eu 2+ 0.3Mn 2 + 0.03Cr 3+ Fluorescent powder.

[0101] Performance testing

[0102] 1) Figure 1 The XRD pattern of the phosphor prepared in Example 1 is shown below. Figure 1 As can be seen, all diffraction peaks of the phosphor match well with the standard PDF card, indicating that BaMgAl was successfully synthesized. 10 O 17 It contains no other impurity phases.

[0103] Figure 2 The image shown is the EDS spectrum of the phosphor prepared in Example 1. Figure 2 It can be seen that the constituent elements Ba, Mg, Al, O, Eu, Mn, and Cr were successfully detected on the surface of the phosphor particles. Each element was uniformly distributed across the entire sample particle surface, indicating that Eu, Mn, and Cr were successfully incorporated into BaMgAl. 10 O 17 in the matrix.

[0104] 2) Figure 3 The following is the excitation and emission spectrum of the phosphor in Example 1, obtained from... Figure 3 It is known that the excitation spectrum of this phosphor covers 250–400 nm, with the optimal excitation at 335 nm; the emission is a broadband emission of 450–750 nm, with the optimal emission at 692 nm, which belongs to near-infrared emission. Therefore, this phosphor can be excited by sunlight to emit red light, thus converting the poorly spectral response of blue-violet light in solar cells into better-responding red light, achieving spectral conversion.

[0105] 3) Figure 4 The quantum efficiency diagram of the phosphor in Example 1 is shown below. Figure 4 It is known that this phosphor has excellent absorption coefficient and quantum efficiency. Under 365nm ultraviolet light excitation, the absorption coefficient AE is as high as 86.1%, and the internal quantum efficiency (IQE) and external quantum efficiency (EQE) are 79.5% and 68.4%, respectively. The excellent quantum efficiency of this phosphor ensures high light conversion efficiency.

[0106] 4) Figure 5 This is a particle size distribution diagram of the phosphor in Example 1, from... Figure 5 It can be seen that the particle size distribution is mainly concentrated in the range of 5–15 μm, with an average particle size of 10.72 μm, which is at the micrometer level. Therefore, the fluorescent material has a small size, which ensures the luminescence intensity of the material without significantly hindering sunlight, thus guaranteeing high light conversion efficiency.

[0107] 5) Figure 6 This is a comparison chart of the luminescence intensity of the phosphors in Example 1 and Comparative Example 1. Figure 6 It is known that adding the flux AlF3 can effectively improve the luminescence performance of phosphors.

[0108] 6) The performance of the solar cell containing the BAM-EVA energy down-conversion thin film coating prepared in Example 1 was tested under vertical irradiation using a solar simulator. The difference in photoelectric conversion efficiency of the silicon-based solar cell before and after coating was observed. The IV curves of the bare cell and the coated solar cell were obtained as follows: Figure 8 As shown. By Figure 8 It can be seen that after coating with BAM-EVA light conversion film, the J of the battery...SC There is a clear increasing trend.

[0109] 7) Verify the effect of the BAM-EVA energy down-conversion thin film on the solar cell. The external quantum efficiency (EQE) curves of the solar cell containing the BAM-EVA energy down-conversion thin film coating prepared in Example 1 in the wavelength range of 300–1100 nm are shown below. Figure 9 As shown. By Figure 9 It can be seen that in the blue light range, the external quantum efficiency of the bare cell sample is lower than that of the sample with the BAM-EVA-loaded energy downconversion thin film coating. However, in other spectral ranges, the EQE curves of the two devices are basically the same. Therefore, it can be concluded that J SC The increase in efficiency is related to the application of BAM-EVA energy down-conversion thin films. These films enhance the absorption of blue-violet light by solar cells, converting it into red light with a stronger photoelectric response, thus effectively improving the photoelectric conversion efficiency. Therefore, based on the light conversion effect of BAM-EVA energy down-conversion thin films, silicon-based solar cells with BAM-EVA coatings exhibit higher conversion efficiency compared to bare solar cells.

[0110] 7) The IV curves of the silicon-based solar cells in Examples 1 to 5 were tested, and the obtained parameters are shown in Table 2.

[0111] Table 2. IV curve parameters of silicon-based solar cells in Examples 1-5

[0112]

[0113]

[0114] The fluorescent material provided by this invention can provide extremely long wavelength near-infrared light (NIR) from near-ultraviolet (NUV), a light source with extremely short wavelengths in sunlight. This can greatly improve the efficiency of silicon-based solar cells. As shown in Table 2, Example 1 has the highest improvement in the photoelectric conversion efficiency of silicon-based solar cells. The fluorescent material can improve the photoelectric conversion efficiency by up to 6.684%.

[0115] 8) Figure 10 This is a comparison chart of the luminescence intensity of the phosphors prepared in Examples 1, 6-10; from Figure 10 As can be seen from Cr 3+ With increasing doping concentration, Eu at 450 nm 2+ The intensity of the blue emission peak gradually decreases, and at 515 nm, Mn 2+ The intensity of the green emission peak gradually decreases, while the Cr emission peak at 693 nm... 3+The intensity of the characteristic emission peak gradually increases, and the luminescence intensity reaches its highest point when z = 0.03. Subsequently, the luminescence intensity of the sample decreases due to concentration quenching.

[0116] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A red fluorescent material for solar cells, characterized in that, The chemical composition is Ba 1-x Mg 1-y Al 10-z O 17 :xEu 2+ ,yMn 2+ ,zCr 3+ ; among which, 0 <x≤0.5,0<y≤0.5,0<z≤0.05。 2. The red fluorescent material according to claim 1, characterized in that, x=0.3, y=0.3 and z=0.

03.

3. The method for preparing the red fluorescent material according to claim 1 or 2, characterized in that, Includes the following steps: Ba source, Mg source, Al source, Eu source, Mn source, Cr source and flux were ground and mixed. The resulting mixture was sintered in a reducing atmosphere and the surface sample was removed to obtain a red fluorescent material.

4. The preparation method according to claim 3, characterized in that, The Ba source includes BaO, BaCO3, Ba(OH)2·8H2O, Ba(NO3)2, BaSO4, or BaCl2; The Mg source includes MgO, MgCO3, Mg(OH)2, Mg(NO3)2·6H2O or MgCl2; The Al source includes Al2O3, Al(OH)3, AlOOH, Al(NO3)3·9H2O, Al2(SO4)3 or AlCl3; The Eu source includes Eu2O3, Eu2(SO4)3, Eu(NO3)3·6H2O, EuCl2, EuCl3 or EuF3; The Mn source includes MnO, MnO2, Mn2O3, Mn3O4, MnCO3, Mn(OH)2, Mn(NO3)2·6H2O or MnCl2·4H2O; The Cr source includes Cr2O3, Cr(NO3)3·9H2O, CrCl2·6H2O or CrF3; The flux includes AlF3, KF, LiF, NaF, BaF2, NH4Cl or H3BO3.

5. The preparation method according to claim 3, characterized in that, The mass of the flux is 0-7 wt% of the total mass of the Ba source, Mg source, Al source, Eu source, Mn source and Cr source, and is not 0; the reducing atmosphere is a N2+H2 mixed atmosphere, and the volume ratio of N2 to H2 is 9:1; the sintering temperature is 1450-1600℃, and the time is 2-6 h.

6. The application of the red fluorescent material according to any one of claims 1 to 2 or the red fluorescent material prepared by the preparation method according to any one of claims 3 to 5 in solar cells.

7. A method for preparing an energy down-conversion thin film, characterized in that, Includes the following steps: An organic polymer is mixed with an organic solvent, and the resulting colloidal polymer is then mixed with a red fluorescent material to obtain a powder mixture; the red fluorescent material is the red fluorescent material according to any one of claims 1 to 2 or the red fluorescent material prepared by the preparation method according to any one of claims 3 to 5. The adhesive powder mixture is coated onto the surface of a solar cell and dried to obtain an energy down-conversion film.

8. The preparation method according to claim 7, characterized in that, The organic polymers include ethylene-vinyl acetate copolymer, polyvinylpyrrolidone, ethylene-octene copolymer, or epoxy resin.

9. The preparation method according to claim 7 or 8, characterized in that, The ratio of the organic polymer to the organic solvent is 3g:10mL to 1g:20mL; the mass ratio of the red fluorescent material to the colloidal polymer is 1:10 to 100.

10. The energy down-conversion thin film prepared by the preparation method according to any one of claims 7 to 9.

Images