Red fluorescent material, preparation method and application thereof, lower transfer layer and preparation thereof

Abstract

The invention relates to the technical field of luminescent materials, in particular to a red fluorescent material, a preparation method and application thereof, a lower transfer layer and preparation of the lower transfer layer, the red fluorescent material has a chemical formula of K < 0.5 > La < 0.5 > Sr Mg < 1-x > (W < 1-y > Tey) < 1-z > O6: zMn < 4 + >, xLu < 3 + >, wherein 0 lt; x is less than or equal to 0.1, 0lt; y is less than or equal to 0.5, 0lt; and z < = 0.05. The material can be excited by visible light and near ultraviolet in sunlight and can emit red light at the same time, namely sunlight in the wavelength range of 300-600 nm is converted into dark red light in the wavelength range of 600-800 nm, the problem that a silicon-based solar cell is poor in short-wavelength photoelectric conversion efficiency is solved, and the photoelectric conversion efficiency of the silicon-based solar cell is improved.

Description

A red light fluorescent material, its preparation method and application, a down-conversion layer and its preparation Technical Field

[0001] The present invention relates to the technical field of luminescent materials, and particularly to a red light fluorescent material, its preparation method and application, a down-conversion layer and its preparation. Background Art

[0002] Solar energy, as the current mainstream renewable energy, has the advantages of environmental friendliness, easy utilization, abundant reserves, etc. In recent years, it has developed rapidly, and the photovoltaic installed capacity has been increasing year by year. The utilization of solar energy mainly focuses on the photoelectric conversion of solar cells, so the photovoltaic power generation is directly affected by the photoelectric conversion efficiency of solar cells.

[0003] Among many solar cells, silicon cells have become the main force of photoelectric conversion due to their high stability and low cost. However, the maximum value of the photoelectric conversion efficiency of existing silicon cells is about 26%, and its further improvement is restricted by various factors. One of the factors is the spectral response problem: at short wavelengths, each photon has a large amount of energy, and any energy higher than the silicon bandgap energy value cannot be fully utilized by the silicon cell. The energy exceeding the bandgap will be lost in the form of heat, and the high-energy incident energy cannot be fully utilized, resulting in the inability to fully utilize high-energy photons. At the same time, the silicon cell has a weak absorption ability for low-energy photons and cannot absorb low-energy light. And due to the poor penetration ability of short-wavelength light, it is difficult to enter the surface of the silicon cell to generate the photoelectric effect. Therefore, the silicon cell has a poor spectral response at 300 - 600 nm and a strong spectral response at > 600 nm. Summary of the Invention

[0004] The purpose of the present invention is to provide a red light fluorescent material, its preparation method and application, a down-conversion layer and its preparation. This red light fluorescent material can be excited by near-ultraviolet and visible light in sunlight and simultaneously emit red light, solving the problem of poor short-wavelength photoelectric conversion efficiency of silicon-based solar cells, so as to improve the photoelectric conversion efficiency of silicon-based solar cells.

[0005] To achieve the above purpose, the present invention provides a red light fluorescent material with the chemical formula: K 0.5 La 0.5 SrMg 1-x (W 1-y Te y ) 1-z O6:zMn 4+ ,xLu 3+ ; where 0 < x ≤ 0.1, 0 < y ≤ 0.5, 0 < z ≤ 0.05, and x is the molar percentage of Lu 3+ y is the molar percentage of Te, and z is the molar percentage of Mn 4+ .

[0006] In the present invention, x is preferably 0.01 < x ≤ 0.07, more preferably 0.02 < x ≤ 0.05; y is preferably 0.1 < y ≤ 0.4, more preferably 0.2 < y ≤ 0.35; z is preferably 0.005 < z ≤ 0.04, more preferably 0.01 < z ≤ 0.02.

[0007] In one embodiment of the present invention, x = 0.03, y = 0.3, z = 0.015, and the chemical formula of the corresponding red fluorescent material is: K 0.5 La 0.5 SrMg 0.97 (W 0.7 Te 0.3 ) 0.985 O6:0.015Mn 4+ ,0.03Lu 3+ .

[0008] The present invention also provides a preparation method of the above red fluorescent material, comprising the following steps: mixing a potassium source, a lanthanum source, a strontium source, a magnesium source, a tungsten source, a tellurium source, a manganese source and a lutetium source according to the above stoichiometric ratio, and sintering in an oxidizing atmosphere to obtain the red fluorescent material.

[0009] In the present invention, the specific process of the preparation method of the red fluorescent material includes: mixing the above raw materials according to the stoichiometric ratio, placing them in an agate mortar, adding ethanol for grinding, then loading the ground powder into an alumina crucible, placing the alumina crucible in a high-temperature tube furnace, sintering in an oxidizing atmosphere, taking out the sintered product after sintering, placing it in a porcelain mortar for secondary grinding, and drying to obtain the red fluorescent material. The dosage of the ethanol is not limited, and it is only used as a grinding aid, and can be adjusted according to the demand to ensure sufficient grinding; the oxidizing atmosphere is preferably air; there are no special limitations on the secondary grinding and drying, and they can be carried out according to the processes well-known to those skilled in the art.

[0010] In the present invention, the potassium source preferably includes at least one of K2O, K2CO3, KNO3, KOH, K2SO4, KCl; the lanthanum source preferably includes at least one of La2O3, La2(CO3)3.nH2O, La(NO3)3, LaCl3, La2(SO4)3, La(OH)3; the strontium source preferably includes at least one of SrO, SrCO3, Sr(OH)2, Sr(NO3)2, SrSO4, SrCl2; the magnesium source preferably includes at least one of MgO, 4MgCO3·Mg(OH)2·4H2O, MgCO3, Mg(OH)2, Mg(NO3)2·6H2O, MgCl2; the tungsten source preferably includes WO2, WO3, H2WO4, (NH4) 10At least one of H2(W2O7)6; the tellurium source preferably includes at least one of H6TeO6, (NH4)2TeO4, and TeO2; the manganese source preferably includes at least one of MnO, MnO2, Mn2O3, Mn3O4, MnCO3, Mn(OH)2, Mn(NO3)2·6H2O, and MnCl2·4H2O; the lutetium source preferably includes at least one of Lu2O3, LuCl3, Lu(NO3)3·6H2O, and Lu2(SO4)3·H2O.

[0011] In this invention, the sintering temperature is preferably 1200-1550℃, more preferably 1300-1450℃, and even more preferably 1400℃, and the sintering time is preferably 2-10h, more preferably 3-8h, and even more preferably 6h.

[0012] The present invention also provides the application of the above-mentioned red fluorescent material or the red fluorescent material prepared by the above-mentioned method in solar cells.

[0013] The present invention also provides a method for preparing a lower transfer layer, comprising the following steps: S1, mixing an organic polymer with a solvent to obtain a colloidal polymer; S2, mixing the colloidal polymer with a red fluorescent material to obtain a powder mixture; S3, coating the powder mixture onto the back of a silicon solar cell module, bonding it to a reflective film, and drying it to obtain a lower transfer layer; wherein the organic polymer in S1 includes ethylene-vinyl acetate copolymer (EVA), polyvinylpyrrolidone, ethylene-octene copolymer (POE), or epoxy resin; wherein the red fluorescent material in S2 is the red fluorescent material described in the above technical solution or the red fluorescent material prepared by the method described in the above technical solution.

[0014] In this invention, the source and type of ethylene-vinyl acetate copolymer, polyvinylpyrrolidone, ethylene-octene copolymer or epoxy resin are not limited, and commercially available products well known to those skilled in the art can be used.

[0015] In this invention, the organic polymer mentioned in S1 is preferably an ethylene-vinyl acetate copolymer. The lower transfer layer prepared by using ethylene-vinyl acetate copolymer as the organic polymer not only has high light conversion efficiency but also high adhesion performance, enabling large-scale application.

[0016] In this invention, the solvent is preferably toluene.

[0017] In this invention, the mass-to-volume ratio of the organic polymer to the solvent in S1 is preferably 1-3g:10-20mL, more preferably 1g:4mL, and the solvent is preferably toluene.

[0018] In the present invention, the specific process of mixing the colloidal polymer with the red light fluorescent material in S2 includes: after mixing the colloidal polymer with the red light fluorescent material, placing them in a vacuum degassing machine and stirring for 5 minutes (stirring makes the red light fluorescent material disperse evenly in the colloidal polymer, avoiding the existence of air bubbles and segregation phenomena), to obtain a powder mixture.

[0019] In the present invention, the mass ratio of the red light fluorescent material to the colloidal polymer in S2 is preferably 1:1 - 20, more preferably 1:2 - 10, and further preferably 1:3 - 7.

[0020] In the present invention, the specific process in S3 includes: at room temperature, applying the powder mixture on the back of the silicon solar cell module, bonding it with the reflective film until the surface is smooth, removing the battery, and drying to obtain the lower transfer layer. The drying method is preferably natural air drying.

[0021] In the present invention, the coating method in S3 includes spin coating using a spin coater, and the rotation speed of the spin coater is 300 - 1500 rpm.

[0022] In the present invention, the reflective film uses a commercial reflective film, and there are no special restrictions on its source and model, and any commercially available product well-known to those skilled in the art can be used. There are no special restrictions on the silicon solar cell, and any commercially available product well-known in the art can be used.

[0023] In the present invention, unless otherwise specified, all the raw materials required for preparation are commercially available products well-known to those skilled in the art.

[0024] The present invention also provides a lower transfer layer prepared by the above method for preparing the lower transfer layer.

[0025] The present invention has the following beneficial effects: The present invention provides a red light fluorescent material, and its chemical formula is: K 0.5 La 0.5 SrMg 1-x (W 1-y Te y ) 1-z O6:zMn 4 + ,xLu 3+ ; where 0 < x ≤ 0.1, 0 < y ≤ 0.5, 0 < z ≤ 0.05. The red light fluorescent material provided by the present invention uses Mn 4+ as the activator, its excitation is located at 250 - 600 nm, and the emission is located at 600 - 800 nm. Since Mn 4+ is a parity-forbidden transition, its absorption is restricted. The present invention introduces Te to replace W in the K 0.5 La 0.5 SrMgWO6 matrix, reducing the symmetry of this site, thereby partially breaking Mn 4+The forbidden transition enhances its luminescence intensity. Furthermore, when Mn... 4+ Replace W 6+ Charge imbalances occur in the matrix, leading to defects. These defect energy levels absorb energy and undergo non-radiative transitions, resulting in a decrease in luminescence intensity. This invention addresses this issue by using Mg... 2+ Point introduction of Lu 3+ The charge was balanced, which improved the luminescence intensity of the sample. This red fluorescent material has a broad excitation range, and can be excited by wavelengths of 300-600 nm in sunlight (where silicon-based solar cells have a poor spectral response), while emitting red light at wavelengths of 600-800 nm (where silicon-based solar cells have a strong spectral response). This improves the spectral mismatch problem of silicon-based solar cells, thereby enhancing the photoelectric conversion efficiency of silicon-based solar cells.

[0026] This invention also provides a method for preparing the above-mentioned red fluorescent material, comprising the following steps: mixing potassium source, lanthanum source, strontium source, magnesium source, tungsten source, tellurium source, manganese source, and lutetium source in the above stoichiometric ratio, and then sintering in an oxidizing atmosphere to obtain the red fluorescent material. The preparation method provided by this invention employs a high-temperature solid-state method and sintering in an oxidizing atmosphere. The preparation method is simple and produces no harmful byproducts, making it suitable for large-scale production.

[0027] This invention also provides a method for preparing a lower transfer layer, comprising the following steps: S1, mixing an organic polymer with a solvent to obtain a colloidal polymer; S2, mixing the colloidal polymer with a red fluorescent material to obtain a powder mixture; S3, coating the powder mixture onto the back of a silicon solar cell module, bonding it to a reflective film, and drying it to obtain a lower transfer layer; wherein the organic polymer includes ethylene-vinyl acetate copolymer, polyvinylpyrrolidone, ethylene-octene copolymer, or epoxy resin; and the red fluorescent material is the aforementioned red fluorescent material or a red fluorescent material prepared by the aforementioned method for preparing red fluorescent materials.

[0028] This invention introduces a red fluorescent material into an organic polymer as a light-converting agent and coats it on the back of a solar cell to prepare a lower transfer layer. The prepared lower transfer layer enhances the absorption capacity of the solar cell spectrum by effectively converting the spectral response difference portion of sunlight into near-red or red light that is easily absorbed by silicon-based solar cells, thereby improving the utilization rate of sunlight and thus improving the photoelectric conversion efficiency.

[0029] The back reflective film prepared by this invention has high conversion efficiency and does not block sunlight, thereby maximizing the photoelectric conversion efficiency of the battery.

[0030] Silicon-based solar cells generally exhibit weak photoelectric response in the short wavelength range (300-600 nm), but strong photoelectric response in the red and near-infrared range (600-1100 nm). The down-transfer layer prepared in this invention can absorb short-wavelength light and emit red or near-infrared light that is beneficial for absorption by silicon-based solar cells, while reducing scattered light, thereby improving its utilization of sunlight. Therefore, the down-transfer layer provided by this invention transmits more red light, which is absorbed by the silicon-based solar cell, thus improving the photoelectric conversion efficiency of the silicon-based solar cell.

[0031] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0032] Figure 1 is the XRD pattern of the red fluorescent material obtained in Example 1 of the present invention; Figure 2 is the EDS pattern of the red fluorescent material obtained in Example 1 of the present invention; Figure 3 is the excitation and emission spectrum of the red fluorescent material obtained in Example 1 of the present invention; Figure 4 is the quantum efficiency diagram of the red fluorescent material obtained in Example 1 of the present invention; Figure 5 is the particle size distribution diagram of the red fluorescent material obtained in Example 1 of the present invention; Figure 6 is the particle size distribution diagram of the fluorescent materials obtained in Comparative Examples 1-5 of the present invention; Figure 7 is a comparison diagram of the luminescence intensity of the materials prepared in Examples 1-4 and Comparative Example 4 of the present invention; Figure 8 is a schematic diagram of the structure of the lower transfer layer prepared in Application Example 1 of the present invention; Figure 9 is the IV curve of the battery without the lower transfer layer and the battery with the lower transfer layer in Application Example 1 of the present invention. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments. Unless otherwise defined, the technical or scientific terms used in this invention should be understood in their ordinary sense by those skilled in the art. The features mentioned above or in the specific examples mentioned in this invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the invention and are not intended to limit the scope of the invention.

[0034] Example 1 This example provides a red fluorescent material with the chemical formula: K 0.5 La 0.5 SrMg 0.97 (W 0.7 Te 0.3 ) 0.985 O6:0.015Mn 4+ 0.03Lu 3+ .

[0035] The preparation method of the above-mentioned red fluorescent material includes the following steps: Weigh 0.0691g of K2CO3, 0.1629g of La2O3, 0.2953g of SrCO3, 0.0782g of MgO, 0.3197g of WO3, 0.0943g of TeO2, 0.0119g of Lu2O3 and 0.0035g of MnCO3 according to the above chemical composition, mix them, place them in an agate mortar, add 5mL of ethanol for grinding, and then put them into an alumina crucible. Place the alumina crucible in a high-temperature tube furnace and sinter at 1400℃ for 6 hours in an air atmosphere. After sintering, take out the sintered product, place it in a porcelain mortar for secondary grinding, and dry it to obtain the red fluorescent material, K2CO3. 0.5 La 0.5 SrMg 0.97 (W 0.7 Te 0.3 ) 0.985 O6:0.015Mn 4+ 0.03Lu 3+ .

[0036] Example 2 This example provides a red fluorescent material with the chemical formula: K 0.5 La 0.5 SrMg 0.99 (W 0.7 Te 0.3 ) 0.985 O6:0.015Mn 4+ 0.01Lu 3+ .

[0037] The preparation method of the above-mentioned red fluorescent material includes the following steps: Weigh 0.0691g of K2CO3, 0.1629g of La2O3, 0.2953g of SrCO3, 0.0782g of MgO, 0.3197g of WO3, 0.0943g of TeO2, 0.0040g of Lu2O3 and 0.0035g of MnCO3 according to the above chemical composition, mix them, place them in an agate mortar, add 5mL of ethanol for grinding, and then put them into an alumina crucible. Place the alumina crucible in a high-temperature tube furnace and sinter it at 1400℃ for 6h in an air atmosphere. After sintering, take out the sintered product, place it in a porcelain mortar for secondary grinding, and dry it to obtain the red fluorescent material.

[0038] Example 3 This example provides a red fluorescent material with the chemical formula: K 0.5 La 0.5 SrMg 0.95 (W 0.7 Te 0.3 ) 0.985 O6:0.015Mn 4+0.05Lu 3+ .

[0039] The preparation method of the above-mentioned red fluorescent material includes the following steps: Weigh 0.0691g of K2CO3, 0.1629g of La2O3, 0.2953g of SrCO3, 0.0782g of MgO, 0.3197g of WO3, 0.0943g of TeO2, 0.0198g of Lu2O3 and 0.0035g of MnCO3 according to the above chemical composition, mix them, place them in an agate mortar, add 5mL of ethanol for grinding, and then put them into an alumina crucible. Place the alumina crucible in a high-temperature tube furnace and sinter it at 1400℃ for 6h in an air atmosphere. After sintering, take out the sintered product, place it in a porcelain mortar for secondary grinding, and dry it to obtain the red fluorescent material.

[0040] Example 4 This example provides a red fluorescent material with the chemical formula: K 0.5 La 0.5 SrMg 0.93 (W 0.7 Te 0.3 ) 0.985 O6:0.015Mn 4+ 0.07Lu 3+ .

[0041] The preparation method of the above-mentioned red fluorescent material includes the following steps: Weigh 0.0691g of K2CO3, 0.1629g of La2O3, 0.2953g of SrCO3, 0.0782g of MgO, 0.3197g of WO3, 0.0943g of TeO2, 0.0278g of Lu2O3 and 0.0035g of MnCO3 according to the above chemical composition, mix them, place them in an agate mortar, add 5mL of ethanol for grinding, and then put them into an alumina crucible. Place the alumina crucible in a high-temperature tube furnace and sinter it at 1400℃ for 6h in an air atmosphere. After sintering, take out the sintered product, place it in a porcelain mortar for secondary grinding, and dry it to obtain the red fluorescent material.

[0042] Comparative Example 1 provides a fluorescent material that is essentially the same as the red fluorescent material provided in Example 1, except that x=0, y=0, and its chemical formula is: K 0.5 La 0.5 SrMgW 0.985 O6:0.015Mn 4+ .

[0043] The preparation method of the above-mentioned fluorescent material includes the following steps: Weigh 0.0691g of K2CO3, 0.1629g of La2O3, 0.2953g of SrCO3, 0.0782g of MgO, 0.4567g of WO3 and 0.0035g of MnCO3 according to the above chemical composition, mix them, place them in an agate mortar, add 5mL of ethanol for grinding, and then put them into an alumina crucible. Place the alumina crucible in a high-temperature tube furnace and sinter it at 1400℃ for 6h in an air atmosphere. After sintering, take out the sintered product, place it in a porcelain mortar for secondary grinding, and dry it to obtain the fluorescent material.

[0044] Comparative Example 2 provides a fluorescent material that is essentially the same as the red fluorescent material provided in Example 1, except that x=0, y=0.1, and its chemical formula is: K 0.5 La 0.5 SrMg(W 0.9 Te 0.1 ) 0.985 O6:0.015Mn 4+ .

[0045] The preparation method of the above-mentioned fluorescent material includes the following steps: Weigh 0.0691g of K2CO3, 0.1629g of La2O3, 0.2953g of SrCO3, 0.0782g of MgO, 0.4110g of WO3, 0.0314g of TeO2 and 0.0035g of MnCO3 according to the above chemical composition, mix them, place them in an agate mortar, add 5mL of ethanol for grinding, and then put them into an alumina crucible. Place the alumina crucible in a high-temperature tube furnace and sinter it at 1400℃ for 6h in an air atmosphere. After sintering, take out the sintered product, place it in a porcelain mortar for secondary grinding, and dry it to obtain the fluorescent material.

[0046] Comparative Example 3 provides a fluorescent material that is essentially the same as the red fluorescent material provided in Example 1, except that x=0 and y=0.2, and its chemical formula is: K 0.5 La 0.5 SrMg(W 0.8 Te 0.2 ) 0.985 O6:0.015Mn 4+ .

[0047] The preparation method of the above-mentioned fluorescent material includes the following steps: Weigh 0.0691g of K2CO3, 0.1629g of La2O3, 0.2953g of SrCO3, 0.0782g of MgO, 0.3654g of WO3, 0.0629g of TeO2 and 0.0035g of MnCO3 according to the above chemical composition, mix them, place them in an agate mortar, add 5mL of ethanol for grinding, and then put them into an alumina crucible. Place the alumina crucible in a high-temperature tube furnace and sinter it at 1400℃ for 6h in an air atmosphere. After sintering, take out the sintered product, place it in a porcelain mortar for secondary grinding, and dry it to obtain the fluorescent material.

[0048] Comparative Example 4 provides a fluorescent material that is essentially the same as the red fluorescent material provided in Example 1, except that x=0, y=0.3, and its chemical formula is: K 0.5 La 0.5 SrMg(W 0.7 Te 0.3 ) 0.985 O6:0.015Mn 4+ .

[0049] The preparation method of the above-mentioned fluorescent material includes the following steps: Weigh 0.0691g of K2CO3, 0.1629g of La2O3, 0.2953g of SrCO3, 0.0782g of MgO, 0.3197g of WO3, 0.0943g of TeO2 and 0.0035g of MnCO3 according to the above chemical composition, mix them, place them in an agate mortar, add 5mL of ethanol for grinding, and then put them into an alumina crucible. Place the alumina crucible in a high-temperature tube furnace and sinter it at 1400℃ for 6h in an air atmosphere. After sintering, take out the sintered product, place it in a porcelain mortar for secondary grinding, and dry it to obtain the fluorescent material.

[0050] Comparative Example 5 provides a fluorescent material that is essentially the same as the red fluorescent material provided in Example 1, except that x=0, y=0.4, and its chemical formula is: K 0.5 La 0.5 SrMg(W 0.6 Te 0.4 ) 0.985 O6:0.015Mn 4+ .

[0051] The preparation method of the above-mentioned fluorescent material includes the following steps: Weigh 0.0691g of K2CO3, 0.1629g of La2O3, 0.2953g of SrCO3, 0.0782g of MgO, 0.2740g of WO3, 0.1257g of TeO2 and 0.0035g of MnCO3 according to the above chemical composition, mix them, place them in an agate mortar, add 5mL of ethanol for grinding, and then put them into an alumina crucible. Place the alumina crucible in a high-temperature tube furnace and sinter it at 1400℃ for 6h in an air atmosphere. After sintering, take out the sintered product, place it in a porcelain mortar for secondary grinding, and dry it to obtain the fluorescent material.

[0052] Characterization test: The red fluorescent material obtained in Example 1 was subjected to XRD diffraction analysis, and the results are shown in Figure 1. As can be seen from Figure 1, all diffraction peaks of the red fluorescent material match well with the standard PDF card, indicating that the synthesized product is the SrMgWO6 phase and does not contain any other impurity phases.

[0053] The composition of the red fluorescent material obtained in Example 1 was analyzed, and the EDS test results are shown in Figure 2. As can be seen from Figure 2, the constituent elements K, La, Sr, Mg, W, Te, Mn, and Lu were successfully detected on the surface of the red fluorescent material particles obtained in Example 1, and each element was uniformly distributed on the entire sample particle surface.

[0054] The excitation and emission wavelengths of the red fluorescent material obtained in Example 1 were tested, and the results are shown in Figure 3. Figure 3 shows that the excitation spectrum of this red fluorescent material covers 250-600 nm, with an optimal excitation wavelength of 345 nm; the emission is a broadband emission range of 600-800 nm, with an optimal emission wavelength of 693 nm, which falls within the near-infrared emission spectrum. Therefore, this red fluorescent material can be excited by sunlight to emit red light, thus converting the poor spectral response of silicon-based solar cells into better-responding red light, achieving spectral conversion.

[0055] The quantum efficiency of the red fluorescent material obtained in Example 1 was tested, and the results are shown in Figure 4. As can be seen from Figure 4, this red fluorescent material exhibits excellent absorption coefficient and quantum efficiency. Under 365 nm ultraviolet light excitation, the absorption coefficient AE reaches as high as 82.7%, and the internal quantum efficiency (IQE) and external quantum efficiency (EQE) are 93.9% and 77.4%, respectively. The excellent quantum efficiency of this phosphor ensures high light conversion efficiency.

[0056] The particle size distribution of the red fluorescent material obtained in Example 1 was tested, and the results are shown in Figure 5. As can be seen from Figure 5, the particle size distribution of this red fluorescent material is mainly concentrated in the range of 1-10 μm, with an average particle size of 2.61 μm, which is at the micrometer level.

[0057] The particle size distribution of the fluorescent materials obtained in Comparative Examples 1-5 was tested, and the results are shown in Figure 6. Figure 6 shows that the luminescence intensity first increases and then decreases with increasing Te content, reaching its highest value when y=0.3.

[0058] The luminescence intensity of the materials prepared in Examples 1-4 and Comparative Example 4 was tested, and the results are shown in Figure 7. As can be seen from Figure 7, the luminescence intensity first increases and then decreases with the increase of Te, reaching its maximum when y=0.3.

[0059] Application Case: Application Example 1 uses the red fluorescent material obtained in Example 1 as raw material to prepare the lower transfer layer. The specific process includes: weighing 2.5g of ethylene-vinyl acetate copolymer (EVA), 10.0mL of toluene, and 0.5g of the red fluorescent material obtained in Example 1 according to the mass ratio of ethylene-vinyl acetate copolymer (EVA) to red fluorescent material of 5:1 and the mass-volume ratio of ethylene-vinyl acetate copolymer (EVA) to toluene of 1g:4mL.

[0060] S1. Mix 2.5g of ethylene-vinyl acetate copolymer with 10.0mL of toluene to obtain a colloidal polymer; S2. Mix the colloidal polymer with 0.5g of red fluorescent material, place it in a vacuum degassing machine and stir under vacuum for 5min to obtain a powder mixture; S3. Use a spin coater at room temperature to spin coat the powder mixture onto the back of a silicon-based solar cell module (model: heterojunction HJT cell) at a speed of 500rpm (as shown in Figure 8), and bond it to the reflective film until the surface is smooth. Then remove the cell and allow it to air dry naturally to form a silicon-based solar cell with a KLSMWTOML-EVA lower transfer layer.

[0061] Figure 8 shows a schematic diagram of the lower transfer layer structure prepared in this application example.

[0062] Application Example 2 This application example provides a lower transfer layer, the preparation method of which is basically the same as that of Application Example 1, the only difference being: the mass of ethylene-vinyl acetate copolymer (EVA) is 2.5g, the volume of toluene is 10mL, and the red fluorescent material obtained in Example 1 is 0.25g. The remaining steps are the same as those in Application Example 1.

[0063] Application Example 3 This application example provides a lower transfer layer, the preparation method of which is basically the same as that of Application Example 1, the only difference being: the mass of ethylene-vinyl acetate copolymer (EVA) is 2.5g, the volume of toluene is 10mL, and the red fluorescent material obtained in Example 1 is 0.125g. The remaining steps are the same as those in Application Example 1.

[0064] Application Example 4 This application example provides a lower transfer layer, the preparation method of which is basically the same as that of Application Example 1, the only difference being that the rotation speed of the spin coater in S3 is adjusted to 800 rpm, and the other steps are the same as those in Application Example 1.

[0065] Application Example 5 This application example provides a lower transfer layer, the preparation method of which is basically the same as that of Application Example 1, the only difference being that the speed of the spin coater in S3 is adjusted to 1000 rpm, and the other steps are the same as those in Application Example 1.

[0066] Performance testing: The performance of the cells in Application Examples 1-5 without the lower transfer layer (bare cells) was tested under vertical irradiation from a solar simulator, as well as the performance of the cells with the lower transfer layer after coating. The difference in photoelectric conversion efficiency before and after was compared. The results are shown in Table 1.

[0067] Figure 9 shows the IV curves of the cell in Application Example 1 without the lower transfer layer and the cell with the lower transfer layer. As can be seen from Figure 9, after coating the silicon-based solar cell with red fluorescent material, the JSC (Jet Count) of the cell using the lower transfer layer shows a significant increasing trend.

[0068] Table 1 Performance Test Results

[0069] in, .

[0070] As shown in Table 1, the red fluorescent material provided by this invention can absorb short-wavelength near-ultraviolet light to yellow light in sunlight and generate long-wavelength red light, which can greatly improve the efficiency of silicon-based solar cells. Example 1 shows that the red fluorescent material has the best effect on improving the photoelectric conversion efficiency of silicon-based solar cells, with the highest relative improvement of photoelectric conversion efficiency reaching 2.42% (Application Example 1).

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A red fluorescent material, characterized in that, The chemical formula is: K 0.5 La 0.5 SrMg 1-x (W 1-y Te y ) 1-z O6:zMn 4+ ,xLu 3 + ; of which 0 <x≤0.1,0<y≤0.5,0<z≤0.05。 2. The red fluorescent material according to claim 1, characterized in that, The values ​​are x=0.03, y=0.3, and z=0.

015.

3. A method for preparing a red fluorescent material according to claim 1 or 2, characterized in that, Includes the following steps: Potassium, lanthanum, strontium, magnesium, tungsten, tellurium, manganese, and lutetium sources are mixed in the above stoichiometric ratios and then sintered in an oxidizing atmosphere to obtain a red fluorescent material.

4. The method for preparing a red fluorescent material according to claim 3, characterized in that, The potassium source includes at least one selected from K₂O, K₂CO₃, KNO₃, KOH, K₂SO₄, and KCl; the lanthanum source includes at least one selected from La₂O₃, La₂(CO₃)₃·nH₂O, La(NO₃)₃, LaCl₃, La₂(SO₄)₃, and La(OH)₃; the strontium source includes at least one selected from SrO, SrCO₃, Sr(OH)₂, Sr(NO₃)₂, SrSO₄, and SrCl₂; the magnesium source includes at least one selected from MgO, 4MgCO₃·Mg(OH)₂·4H₂O, MgCO₃, Mg(OH)₂, Mg(NO₃)₂·6H₂O, and MgCl₂; the tungsten source includes WO₂, WO₃, H₂WO₄, and (NH₄)₂. 10 The tellurium source includes at least one of H2(W2O7)6; the tellurium source includes at least one of H6TeO6, (NH4)2TeO4, and TeO2; the manganese source includes at least one of MnO, MnO2, Mn2O3, Mn3O4, MnCO3, Mn(OH)2, Mn(NO3)2·6H2O, and MnCl2·4H2O; the lutetium source includes at least one of Lu2O3, LuCl3, Lu(NO3)3·6H2O, and Lu2(SO4)3·H2O.

5. The method for preparing a red fluorescent material according to claim 3, characterized in that, The sintering temperature is 1200-1550℃, and the time is 2-10h.

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

7. A method for preparing a lower transfer layer, characterized in that, Includes the following steps: S1. Mix the organic polymer with a solvent to obtain a colloidal polymer; S2. Mix the colloidal polymer with a red fluorescent material to obtain a powder mixture; S3. Coat the powder mixture onto the back of a silicon solar cell module, bond it to the reflective film, and dry it to obtain a lower transfer layer; The organic polymer mentioned in S1 includes ethylene-vinyl acetate copolymer, polyvinylpyrrolidone, ethylene-octene copolymer, or epoxy resin; The red fluorescent material mentioned in S2 is the red fluorescent material according to claim 1 or 2 or the red fluorescent material prepared by the preparation method of the red fluorescent material according to any one of claims 3-5.

8. The method for preparing a lower transfer layer according to claim 7, characterized in that, In S1, the mass-to-volume ratio of organic polymer to solvent is 1-3g:10-20mL; in S2, the mass ratio of red fluorescent material to colloidal polymer is 1:1-20.

9. The method for preparing a lower transfer layer according to claim 7, characterized in that, The coating method described in S3 includes spin coating using a spin coater with a spin coater speed of 300-1500 rpm.

10. A lower transfer layer prepared by the method for preparing a lower transfer layer according to any one of claims 7-9.

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