A near-infrared luminescent material, a preparation method thereof, and an LED light source containing the luminescent material

Abstract

The present invention discloses a near-infrared luminescent material, a preparation method thereof, and an LED light source comprising the luminescent material. The chemical composition of the luminescent material is represented by the chemical formula A a B b P c O x M y :zCr 3+ Indicates that the A element is selected from one or more of Li, Na, K, Rb, Cs, Mg, Ca, Sr and Ba; the B element is selected from one or more of Al, Ga, Sc, In, Fe, Nd, Ta, Ti, Zr, V, Ni and rare earth elements; the M element is selected from one of F, Cl and N; Cr 3+ is the luminescent central ion, 0.01%≤z≤100%, a, b, x and y are the simplified stoichiometric numbers of the element, 0≤a<10, 0≤b<10, 0≤c<20, 0

Description

Technical Field

[0001] The present invention belongs to the field of luminescent materials, and in particular relates to a near-infrared luminescent material, a preparation method thereof, and an LED light source comprising the luminescent material. Background Art

[0002] Near-infrared light has stronger penetration ability in biological tissues than visible light. At the same time, natural substances exhibit different characteristic absorption of near-infrared light. Based on the unique characteristics of near-infrared light, it has attracted much attention in security monitoring, biometrics, sensing, food / medical testing and plant lighting.

[0003] Near-infrared light sources are essential for the application of near-infrared spectroscopy. Early near-infrared light sources were primarily halogen tungsten lamps, which offered advantages such as a wide emission spectrum and high brightness. However, their low efficiency, bulk, and short lifespan have gradually made them less popular in emerging markets. Light-emitting diodes (LEDs), as the fourth generation of solid-state lighting sources, offer numerous advantages, including high efficiency, energy saving, compact size, pollution-free operation, and long lifespan, making them the preferred energy-saving and environmentally friendly light source. Near-infrared LEDs, which utilize near-ultraviolet or blue light-emitting InGaN chips to excite near-infrared phosphors, offer a wide range of wavelengths and narrow half-width spectrum widths, allowing them to be freely configured to produce pure monochromatic or composite spectra as desired. Furthermore, LED lighting systems generate less heat, occupy less space, and their high durability reduces operating costs. Therefore, developing efficient and stable near-infrared luminescent materials is crucial for achieving high-performance LED light sources.

[0004] However, the near-infrared materials disclosed in the prior art are mainly Cr 3+ Doped oxide and fluoride materials, including Cr 3+ There are many types of doped oxide near-infrared luminescent materials, such as borates, phosphates, gallates, aluminates and silicates. Among these materials, the luminous efficiency and stability of the materials need to be improved because the oxides have relatively high phonon energy and relatively weak covalency. 3+ Among the doped fluoride near-infrared luminescent materials, most materials are synthesized by wet chemical methods and inevitably use HF solutions, which puts the safety of material preparation under test.

[0005] Therefore, how to develop a near-infrared luminescent material that can be excited by blue or red light, has a simple preparation process, high luminous efficiency, and good stability, and use this material to prepare fluorescence-converted near-infrared LED devices for application in many fields such as biometrics, sensing, food / medical testing, and plant lighting has become a technical problem that needs to be solved urgently in this field. Summary of the Invention

[0006] In order to improve the above technical problems, the present invention provides a luminescent material with near-infrared broadband emission, a preparation method thereof, and an LED light source comprising the luminescent material.

[0007] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0008] The present invention provides a near-infrared luminescent material, the chemical composition of the luminescent material is represented by chemical formula A a B b P c O x M y :zCr 3+ Indicates that,

[0009] The element A is selected from one or more of Li, Na, K, Rb, Cs, Mg, Ca, Sr and Ba;

[0010] The B element is selected from one or more of Al, Ga, In, Fe, Nd, Ta, Ti, Zr, V, Ni and rare earth elements;

[0011] The M element is selected from at least one of F, Cl and N;

[0012] Cr 3+ is the luminescent central ion, 0.01%≤z≤100%, preferably 1%≤z≤10%;

[0013] a, b, x and y are the simplest stoichiometric coefficients of the elements, 0≤a<10, 0≤b<10, 0≤c<20, 0 <x<30,0<y<30。

[0014] According to an embodiment of the present invention, the rare earth element is La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc or Y.

[0015] According to an embodiment of the present invention, the luminescent material A a B b P c O x M y :zCr 3+ The invention is prepared by calcining raw materials including A source, B source, P source, M source and Cr source at high temperature.

[0016] According to an embodiment of the present invention, the source A is provided by a compound containing element A. Preferably, the source A is selected from at least one of carbonates, oxides, nitrides, nitrates, and halides containing element A; illustratively, the source A is at least one of Na2CO3, NaF, KF, NaPO4, Li2CO3, LiF, K2CO3, SrF2, CaF2, Rb2CO3, and Cs2CO3.

[0017] According to an embodiment of the present invention, the B source is provided by a compound containing the B element; for example, at least one selected from carbonates, oxides, nitrides, nitrates and halides containing the B element; illustratively, the B source compound is at least one of Al2O3, AlN, AlF3, TiO2, V2O5, ZrO2, Sc2O3, ScF3, In2O3, Ga2O3 and GeO2.

[0018] According to an embodiment of the present invention, the Cr source is provided by a compound containing the Cr element; for example, at least one selected from carbonates, oxides, nitrides, nitrates and halides containing the Cr element; illustratively, the Cr source is at least one of Cr2O3, CrF3, and CrN.

[0019] According to an embodiment of the present invention, the P source is provided by a compound containing the P element; for example, at least one selected from phosphates containing the P element and oxides containing the P element, preferably NaPO4, ammonium dihydrogen phosphate, and sodium dihydrogen phosphate.

[0020] According to an embodiment of the present invention, the M source is provided by a compound containing an M element; for example, provided by at least one of a fluorine source, a chlorine source, and a nitrogen source.

[0021] For example, the fluorine source is at least one of KF, NaF, CaF2, ammonium fluoride, aluminum fluoride and SrF2.

[0022] For example, the chlorine source is at least one of potassium chloride, sodium chloride, ammonium chloride and aluminum chloride.

[0023] For example, the nitrogen source is at least one of AlN and urea.

[0024] According to one embodiment of the present invention, the B source and the M source may be the same, for example, NaF, AlN, or SrF2.

[0025] According to an embodiment of the present invention, the luminescent material may be Na3AlP3O9N:4%Cr 3+ 、Na3TiP3O9N:2%Cr 3+ 、NaAlPO4F:4%Cr 3+ 、KAlPO4F:2%Cr3+ 、NaVPO4F:2%Cr 3+ 、Na5AlP2O8F2:3%Cr 3+ 、Na3Al2P2O8F3:2%Cr 3+ 、SrAl2P2O8F2:4%Cr 3+ 、CaAl2P2O8F2:4%Cr 3+ .

[0026] According to an embodiment of the present invention, the luminescent material can be excited by violet light, blue light or red light. Preferably, the luminescent material has near-infrared broadband emission performance, for example, it can emit near-infrared light with a wavelength range of 650-1300nm, with a peak value in the range of 700-1000nm.

[0027] The luminescent material of the present invention has a relatively high thermal quenching temperature and exhibits excellent luminescent thermal stability.

[0028] <Method for preparing luminescent material>

[0029] The present invention also provides a method for preparing the near-infrared luminescent material, the method comprising the steps of:

[0030] (1) According to chemical formula A a B b P c O x M y :zCr 3+ According to the stoichiometric ratio of each element in the mixture, the A source, the B source, the P source, the M source and the Cr source are mixed to obtain a mixture;

[0031] (2) calcining the mixture to obtain the near-infrared luminescent material.

[0032] According to an embodiment of the present invention, in step (1), according to chemical formula A a B b P c O x M y :zCr 3+ The A source, B source, P source, M source and Cr source are weighed according to the stoichiometric ratio of each element in the reaction mixture, wherein the amount of the P source used can be appropriately excessive, for example, an excess of 5wt.%-200wt.%.

[0033] According to an embodiment of the present invention, in step (1), the A source, the B source, the P source, the M source, and the Cr source may be ground after being mixed. The present invention has no particular limitation on the grinding method, and grinding equipment such as a mortar, a ball mill, and a mixer may be used.

[0034] According to an embodiment of the present invention, in step (2), the calcination can be carried out in air, an inert atmosphere, or a reducing atmosphere. The inert atmosphere is, for example, nitrogen, argon, etc.; the reducing atmosphere is, for example, a mixture of (5% to 15% by volume) H2 and (95% to 85% by volume) N2, or a calcination environment containing carbon powder.

[0035] According to an embodiment of the present invention, in step (2), the calcination temperature is 150-1500°C, preferably 500-1200°C, more preferably 700-1100°C, and exemplarily 150°C, 300°C, 500°C, 700°C, 1000°C, 1200°C, and 1500°C; the calcination time is 1-30h, preferably 5-20h, more preferably 8-15h, and exemplarily 1h, 3h, 5h, 8h, 12h, 15h, 20h, and 30h.

[0036] According to an embodiment of the present invention, in step (2), the calcination is performed at least once, for example, two, three or more times. Preferably, the temperature of each calcination is different from each other. More preferably, the temperature of each calcination is increasing. Preferably, the calcined product of the previous calcination can be ground before the next calcination.

[0037] In an exemplary embodiment of the present invention, in step (2), two calcinations are carried out, the temperature of the first calcination is 150-700°C, exemplified by 150°C, 300°C, 500°C, and 700°C; the time of the first calcination is 1-12h, exemplified by 1h, 3h, 5h, 8h, and 12h; the temperature of the second calcination is 700-1500°C, exemplified by 800°C, 1000°C, 1200°C, and 1500°C; the time of the second calcination is 1-20h, exemplified by 1h, 3h, 5h, 8h, 12h, 15h, and 20h.

[0038] According to an embodiment of the present invention, the preparation method further comprises step (3): post-treating the calcined product to obtain the near-infrared luminescent material. Preferably, in step (3), the post-treating may include grinding, washing, filtering, drying, etc.

[0039] Exemplarily, the drying temperature is 60-100°C.

[0040] For example, the post-treatment may include grinding the calcined product, washing it with deionized water for 1-3 times, then washing it with anhydrous ethanol for 1-2 times, filtering it, and drying it in an oven at 80°C.

[0041] The present invention also provides the use of the above-mentioned luminescent material in a luminescent device, wherein the luminescent device is used in the fields of petrochemical industry, polymer, pharmaceutical, clinical medicine, environmental science, textile industry or food testing.

[0042] Preferably, the light emitting device is a fluorescence conversion type near-infrared LED device. Further, the fluorescence conversion type near-infrared LED device is used in fields such as biometrics, 3D sensing, food / medical testing, agricultural production, or biological imaging.

[0043] The present invention also provides an LED light source, which comprises the above-mentioned near-infrared luminescent material A a B b P c O x M y :zCr 3+ Preferably, the fluorescent conversion layer of the LED light source comprises the above-mentioned near-infrared luminescent material A a B b P c O x M y :zCr 3+ .

[0044] According to an embodiment of the present invention, the LED light source further comprises an LED semiconductor chip, the fluorescent conversion layer is disposed on the LED semiconductor chip, and the fluorescent conversion layer comprises the above-mentioned near-infrared luminescent material A a B b P c O x M y :zCr 3+ .

[0045] According to an embodiment of the present invention, the LED light source further comprises a glue layer, which is arranged on the LED semiconductor chip and contains the luminescent material A uniformly dispersed therein. a B b P c O x M y :zCr 3+ The adhesive in the adhesive layer may be epoxy resin, polycarbonate, or silicone, preferably silicone. There is no particular limitation on the amount of adhesive used, as long as it can be evenly applied to the LED semiconductor chip according to procedures known in the art.

[0046] According to an embodiment of the present invention, the fluorescence conversion layer is coated on an LED semiconductor chip, and the LED semiconductor chip is used to carry the fluorescence conversion layer.

[0047] According to an embodiment of the present invention, the LED semiconductor chip is at least one of a purple LED chip, a blue LED chip, and a red LED chip.

[0048] According to an embodiment of the present invention, the peak value of the purple LED chip is within the range of 280-400 nm.

[0049] According to an embodiment of the present invention, the peak of the blue LED chip is within the range of 420-490 nm.

[0050] According to an embodiment of the present invention, the peak value of the red LED chip is within the range of 590-680 nm.

[0051] According to an embodiment of the present invention, the LED light source is a fluorescence-converted near-infrared LED device. Further, the fluorescence-converted near-infrared LED device is used in fields such as biometrics, sensing, food testing, medical testing, temperature measurement, agricultural production, or biological imaging.

[0052] The present invention also provides a method for preparing the above-mentioned LED light source, comprising the following steps: mixing the above-mentioned luminescent material with glue, and then coating the mixture on an LED semiconductor chip.

[0053] The present invention also provides an LED light source containing the above-mentioned luminescent material for use in the fields of petrochemical industry, polymer, pharmaceutical, clinical medicine, environmental science, textile industry and food testing.

[0054] Beneficial effects of the present invention:

[0055] (1) The broadband near-infrared luminescent material provided by the present invention can be used as a light conversion material for near-ultraviolet LED chips, blue LED chips, and red LED chips, thereby serving as a highly efficient and stable broadband near-infrared luminescent light source. This addresses the narrow bandwidth problem of current infrared LEDs and infrared lasers and can meet the demand for broadband infrared light sources in applications such as food testing, medical testing, agricultural production, or biological imaging. Compared to existing materials, the broadband near-infrared luminescent material of the present invention has higher luminescence stability and luminescence quantum yield.

[0056] (2) The near-infrared luminescent material provided by the present invention has excellent moisture and high temperature stability. After aging for 480 hours at 85°C and 85% humidity, the light output power of the LED light source prepared therefrom is still more than 98% of that at room temperature.

[0057] (3) The preparation process of the luminescent material provided by the present invention is simple, pollution-free and low-cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is the XRD pattern of the luminescent material prepared in Example 1 of the present invention.

[0059] Figure 2 This is the excitation spectrum of the luminescent material prepared in Example 1 of the present invention.

[0060] Figure 3 This is the emission spectrum of the luminescent material prepared in Example 1 of the present invention.

[0061] Figure 4 This is a graph showing how the integrated luminescence intensity of the luminescent material prepared in Example 1 of the present invention changes with temperature. DETAILED DESCRIPTION

[0062] The technical solutions of the present invention will be described in further detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are encompassed within the scope of protection that the present invention is intended to protect.

[0063] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0064] Example 1: Na3AlP3O9N:4%Cr 3+ Preparation of luminescent materials

[0065] This embodiment adopts solid phase reaction method to synthesize, first according to the chemical formula Na3AlP3O9N:4%Cr 3+ The stoichiometric ratios of the elements are weighed, with AlN being 0.1131 g, NaPO4 being 2.4617 g, and Cr2O3 being 0.0187 g (wherein NaPO4 volatilizes during the firing process, so the raw materials need to be added in excess). The above raw materials are mixed evenly in a mortar, then loaded into a corundum crucible, placed in a box furnace, and calcined at 300°C for 5 hours in an air atmosphere. After cooling to room temperature, the materials are ground again. The materials are then placed in an atmosphere furnace and calcined for a second time at 780°C for 8 hours in a nitrogen atmosphere. After the calcination is completed, the obtained sample is ground, washed with deionized water 1-3 times, then washed with anhydrous ethanol 1-2 times, filtered, and dried in an oven at 80°C to obtain the final near-infrared luminescent material.

[0066] Example 2: Na3TiP3O9N:2%Cr 3+ Preparation of luminescent materials

[0067] This embodiment adopts the solid phase reaction method for synthesis. First, 1.1356 g of (NH4)H2PO4, 0.7355 g of Na2CO3, and 1.7624 g of urea are weighed. After mixing the above three raw materials, they are placed in a muffle furnace, kept at 300°C for 2 hours, and then taken out. Then 0.0834 g of TiO2 and 0.0086 g of Cr2O3 are weighed and added to the above calcined raw materials and ground together. After mixing evenly, they are loaded into a corundum crucible and placed in an atmosphere furnace. Under a 5v% H2-95v% N2 mixed gas, a second calcination is carried out at 750°C for 8 hours. After the calcination is completed, the obtained sample is ground, washed with deionized water 1-3 times, and then washed with anhydrous ethanol 1-2 times. After filtering, it is dried in an oven at 80°C to obtain the final near-infrared luminescent material.

[0068] Example 3: NaAlPO4F:4%Cr 3+ Preparation of luminescent materials

[0069] This embodiment adopts solid phase reaction method to synthesize, first according to the chemical formula NaAlPO4F: 4%Cr 3+ The stoichiometric ratios of the elements in the sample were weighed: 0.2546 g NaF, 0.2968 g Al2O3, 0.6973 g (NH4)H2PO4, and 0.0184 g Cr2O3. The raw materials were mixed evenly in a mortar and then placed in a small corundum crucible. The small crucible was then placed in a large crucible filled with carbon powder (the amount of which is generally suitable for covering one-third of the height of the small crucible). The crucible was placed in a box furnace and calcined at 500°C for 4 hours in an air atmosphere. After cooling to room temperature, it was ground again. It was then placed in a box furnace and calcined for a second time at 1050°C for 12 hours. After calcination, the obtained sample was ground, washed with deionized water 1-3 times, then washed with anhydrous ethanol 1-2 times, filtered, and dried in an 80°C oven to obtain the final near-infrared luminescent material.

[0070] Example 4: KAlPO4F:2%Cr 3+ Preparation of luminescent materials

[0071] This embodiment adopts the solid phase reaction method to synthesize, first according to the chemical formula KAlPO4F: 2% Cr 3+The stoichiometric ratios of the elements in the sample were weighed, with KF being 0.3214 g, Al2O3 being 0.2769 g, (NH4)H2PO4 being 0.6374 g, and Cr2O3 being 0.0084 g. The raw materials were mixed evenly in a mortar and then placed in a small corundum crucible. The small crucible was then placed in a large crucible filled with carbon powder (the amount of which is generally appropriate to cover one-third of the height of the small crucible). The crucible was then placed in a box furnace and calcined at 500°C for 4 hours in an air atmosphere. After cooling to room temperature, the crucible was ground again. The sample was then placed in a box furnace and calcined for a second time at 1050°C for 10 hours. After the calcination was completed, the sample was ground, washed with deionized water 1-3 times, then washed with anhydrous ethanol 1-2 times, filtered, and dried in an 80°C oven to obtain the final near-infrared luminescent material.

[0072] Example 5: NaVPO4F:2%Cr 3+ Preparation of luminescent materials

[0073] This embodiment adopts the solid phase reaction method to synthesize, first weighing the raw materials NaF 0.2373g, V2O5 0.5138g, (NH4)H2PO4 0.6850g, Cr2O3 0.0062g, carbon powder 0.0678g (used as reducing agent, V 5+ Restore to V 3+ The above raw materials were mixed evenly in a mortar and then placed in a small corundum crucible. The small crucible was then placed in a large crucible filled with carbon powder. The crucible was then placed in a box furnace and calcined at 500°C for 4 hours in an air atmosphere. After cooling to room temperature, it was ground again. The sample was then placed in a box furnace and calcined for a second time at 1050°C for 10 hours. After calcination, the obtained sample was ground, washed with deionized water 1-3 times, then washed with anhydrous ethanol 1-2 times, filtered, and dried in an 80°C oven to obtain the final near-infrared luminescent material.

[0074] Example 6: Na5AlP2O8F2:3%Cr 3+ Preparation of luminescent materials

[0075] This embodiment adopts solid phase reaction method to synthesize, first according to the chemical formula Na5AlP2O8F2:3%Cr 3+The stoichiometric ratios of the elements in the sample were weighed, with NaF being 0.5665 g, Al2O3 being 0.1334 g, (NH4)H2PO4 being 0.6206 g, and Cr2O3 being 0.0062 g. The raw materials were mixed evenly in a mortar, then placed in a corundum crucible, placed in a box furnace, and calcined at 300°C for 5 hours in an air atmosphere. After cooling to room temperature, the crucible was ground again. The crucible was then placed in a box furnace and calcined for a second time at 800°C for 10 hours. After the calcination was completed, the obtained sample was ground, washed with deionized water 1-3 times, then washed with anhydrous ethanol 1-2 times, filtered, and dried in an oven at 80°C to obtain the final near-infrared luminescent material.

[0076] Example 7: Na3Al2P2O8F3:2%Cr 3+ Preparation of luminescent materials

[0077] This embodiment adopts solid phase reaction method to synthesize, first according to the chemical formula Na3Al2P2O8F3:2%Cr 3+ The stoichiometric ratios of the elements in the mixture were weighed, with NaF being 0.2582 g, Al2O3 being 0.2048 g, (NH4)H2PO4 being 0.4714 g, and Cr2O3 being 0.0062 g. The raw materials were mixed evenly in a mortar, then placed in a corundum crucible, and then placed in an atmosphere furnace. Under a nitrogen atmosphere, they were calcined at 300°C for 5 h. After cooling to room temperature, they were ground again. Thereafter, they were placed in an atmosphere furnace and calcined for a second time at 850°C for 10 h under a nitrogen atmosphere. After the calcination was completed, the obtained sample was ground, washed with deionized water 1-3 times, then washed with anhydrous ethanol 1-2 times, filtered, and dried in an oven at 80°C to obtain the final near-infrared luminescent material.

[0078] Example 8: SrAl2P2O8F2:4%Cr 3+ Preparation of luminescent materials

[0079] This embodiment adopts solid phase reaction method to synthesize, first according to the chemical formula SrAl2P2O8F2:4%Cr 3+The stoichiometric ratios of the elements in the sample were weighed, with SrF2 being 0.3381 g, (NH4)H2PO4 being 0.6192 g, Al2O3 being 0.2636 g, and Cr2O3 being 0.0164 g. The raw materials were mixed evenly in a mortar, then placed in a corundum crucible, placed in a box furnace, and calcined at 300°C for 5 h in an air atmosphere. After cooling to room temperature, the crucible was ground again. The crucible was then placed in an atmosphere furnace and calcined for a second time at 750°C for 8 h in a nitrogen atmosphere. After calcination, the sample was ground, washed with deionized water 1-3 times, then washed with anhydrous ethanol 1-2 times, filtered, and dried in an oven at 80°C to obtain the final near-infrared luminescent material.

[0080] Example 9: CaAl2P2O8F2:4%Cr 3+ Preparation of luminescent materials

[0081] This embodiment adopts solid phase reaction method to synthesize, first according to the chemical formula CaAl2P2O8F2:4%Cr 3+ The stoichiometric ratios of the elements in the sample were weighed, with CaF2 being 0.2408 g, (NH4)H2PO4 being 0.7102 g, Al2O3 being 0.3023 g, and Cr2O3 being 0.0188 g. The raw materials were mixed evenly in a mortar, then placed in a corundum crucible, placed in a box furnace, and calcined at 300°C for 5 h in an air atmosphere. After cooling to room temperature, the mixture was ground again. The mixture was then placed in an atmosphere furnace and calcined for a second time at 780°C for 8 h in a nitrogen atmosphere. After the calcination was completed, the obtained sample was ground, washed with deionized water 1-3 times, then washed with anhydrous ethanol 1-2 times, filtered, and dried in an oven at 80°C to obtain the final near-infrared luminescent material.

[0082] The phase of the near-infrared luminescent material sample of the present invention was analyzed by X-ray powder diffractometer (Minflex 600, Rigaku Corporation, Japan).

[0083] The excitation and emission spectra of the samples were measured using an FLS980 (Edinburgh Instruments) fluorescence spectrometer. Combined with a 77–600 K variable temperature stage, the temperature-dependent emission spectra of the materials were tested to evaluate the thermal stability of the materials.

[0084] The luminescence quantum yield of the material was measured using a fiber optic spectrometer (ideaoptics, PG 2000) connected to an integrating sphere via fiber coupling.

[0085] A constant temperature and humidity test chamber was used to evaluate the material's moisture and high temperature stability in an environment of 85°C and 85% humidity.

[0086] The samples synthesized by solid phase reaction method in Examples 1-9 were all pure phases as shown by XRD analysis. The XRD diffraction pattern of the near-infrared luminescent material prepared in Example 1 is as follows: Figure 1 shown; from Figure 1 It can be seen that the luminescent material is pure phase Na3AlP3O9N.

[0087] The excitation and emission spectra of the samples were measured using a FLS980 (Edinburgh Instruments) fluorescence spectrometer. Figure 2 As shown in the figure, it can be seen that the excitation spectrum of the luminescent material contains three effective excitation bands, namely 250-320nm, 380-500nm and 520-730nm; the emission spectrum of the luminescent material prepared in Example 1 is as shown in FIG. Figure 3 As shown in the figure, it can be seen that the emission spectrum of the luminescent material covers 640-1000nm, and thus has near-infrared broadband emission performance.

[0088] Regarding the thermal stability of the luminescent material, the ratio of the integrated luminous intensity of the luminescent material at 150°C to the integrated luminous intensity at room temperature is used for evaluation. The test method is as follows: the luminescent material is placed on a heating table, excitation light is introduced through an optical fiber, and after the heating table is heated to the target temperature, its emission spectrum is tested. The emission spectrum of the test sample at different temperatures is tested. Figure 4 As shown, the Na3AlP3O9N:4%Cr prepared in Example 1 of the present invention 3+ The ratio of the integrated luminous intensity of the luminescent material at 150°C to the integrated luminous intensity at room temperature can reach 82%, such as Figure 4 .

[0089] The luminescence quantum yield η of the material is calculated using the following formula:

[0090]

[0091] Among them, N em is the number of emitted photons, N ex The quantum yield of the luminescent material provided by the present invention is within the range of 70-85%.

[0092] Moisture and high temperature stability testing of luminescent materials: The near-infrared luminescent materials prepared in Examples 1-9 were aged in a constant temperature and humidity test chamber at 85°C and 85% relative humidity. After 480 hours, the samples were tested for luminescence intensity to evaluate the moisture and high temperature stability of the luminescent materials. The test results are shown in Table 1. As can be seen from Table 1, even in a high temperature and high humidity environment, the luminescence intensity of the luminescent materials of the present invention can still maintain at least 98% of that at room temperature. This demonstrates that the near-infrared luminescent materials prepared in the present invention have high moisture and high temperature stability.

[0093] Table 1

[0094]

[0095] Example 10: LED light source

[0096] This embodiment provides an LED light source, which includes an LED semiconductor chip and the luminescent material prepared in Example 1, wherein the LED semiconductor chip is a commercially available blue light LED chip with a wavelength of 450 nm.

[0097] Preparation method of the above LED light source: prepare the near infrared luminescent material Na3AlP3O9N:4%Cr 3+ It is uniformly mixed in silica gel at a mass ratio of 1:1, and then coated on the LED semiconductor chip. After curing, an LED light source is obtained.

[0098] The performance of the LED light source prepared in Example 1 was tested using the HASS-2000 (Hangzhou Yuanfang Optoelectronic Information Co., Ltd.) single LED / module optical, color, and electrical testing system at a test current of 60 mA and a voltage of 3 V. The light source's optical output power in the near-infrared range reached 21 mW (at a current of 350 mA and a voltage of 3 V, the light source's optical output power in the near-infrared range reached 92 mW).

[0099] The above is an exemplary description of the embodiments of the present invention. However, the scope of protection of the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc. made by those skilled in the art within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A near-infrared luminescent material, characterized in that: The luminescent material is Na3AlP3O9N:4%Cr 3+ 、Na3Al2P2O8F 3: 2%Cr 3+ .

2. The near-infrared luminescent material according to claim 1, characterized in that The luminescent material can be excited by violet light, blue light or red light.

3. The near-infrared luminescent material according to claim 1 or 2, characterized in that The luminescent material has near-infrared broadband emission performance and can emit near-infrared light with a wavelength range of 650-1300 nm, with a peak value in the range of 700-1000 nm.

4. The method for preparing the near-infrared luminescent material according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: The solid phase reaction method was used to synthesize the product. First, the chemical formula was Na3AlP3O9N:4%Cr 3+ The stoichiometric ratios of the elements were weighed: 0.1131 g AlN, 2.4617 g NaPO4, and 0.0187 g Cr2O3. The raw materials were mixed evenly in a mortar, then placed in a corundum crucible, and placed in a box furnace. The crucible was calcined at 300°C for 5 h in an air atmosphere, and then ground again after cooling to room temperature. Then, the sample was placed in an atmosphere furnace and calcined for a second time at 780°C for 8 hours under a nitrogen atmosphere. After the calcination, the sample was ground, washed with deionized water 1-3 times, and then washed with anhydrous ethanol 1-2 times. After filtering, it was dried in an oven at 80°C to obtain the final near-infrared luminescent material. The solid phase reaction method was used to synthesize the product. First, the chemical formula was Na3Al2P2O8F3:2%Cr 3+ The stoichiometric ratios of the elements were weighed: 0.2582 g NaF, 0.2048 g Al2O3, 0.4714 g (NH4)H2PO4, and 0.0062 g Cr2O3. The raw materials were mixed evenly in a mortar, then placed in a corundum crucible, and then placed in an atmosphere furnace. They were calcined at 300°C for 5 h under a nitrogen atmosphere, and then ground again after cooling to room temperature. Then it was placed in an atmosphere furnace and calcined for a second time at 850°C for 10 hours under a nitrogen atmosphere. After calcination, the obtained sample was ground, washed with deionized water 1-3 times, and then washed with anhydrous ethanol 1-2 times. After filtering, it was dried in an oven at 80°C to obtain the final near-infrared luminescent material.

5. Use of the near-infrared luminescent material according to any one of claims 1 to 3 and / or the luminescent material obtained by the preparation method according to claim 4 in a luminescent device, wherein the luminescent device is used in the fields of petrochemical industry, polymer, pharmaceutical, clinical medicine, environmental science, textile industry or food testing.

6. The use according to claim 5, characterized in that The light-emitting device is a fluorescence conversion type near-infrared LED device, which is used in the fields of biometrics, 3D sensing, food / medical testing, agricultural production or biological imaging.

7. An LED light source, characterized in that: The LED light source comprises the near-infrared luminescent material according to any one of claims 1 to 3 and / or the near-infrared luminescent material Na3AlP3O9N:4%Cr prepared by the preparation method according to claim 4 3+ or Na3Al2P2O8F3:2%Cr 3+ .

8. The LED light source according to claim 7, wherein: The fluorescent conversion layer of the LED light source comprises the near-infrared luminescent material according to any one of claims 1 to 3 and / or the near-infrared luminescent material Na3AlP3O9N:4%Cr prepared by the preparation method according to claim 4. 3+ or Na3Al2P2O8F3:2%Cr 3+ .

9. The LED light source according to claim 8, characterized in that: The LED light source also includes an LED semiconductor chip, and the fluorescent conversion layer is placed on the LED semiconductor chip. The fluorescent conversion layer contains the above-mentioned near-infrared luminescent material Na3AlP3O9N:4%Cr 3+ or Na3Al2P2O8F3:2%Cr 3+ .

10. The LED light source according to claim 9, characterized in that: The LED light source further comprises a glue layer, which is arranged on the LED semiconductor chip and contains the luminescent material Na3AlP3O9N:4%Cr uniformly dispersed in the glue layer. 3+ or Na3Al2P2O8F3:2%Cr 3+ .

11. The LED light source according to claim 10, characterized in that: The fluorescent conversion layer is coated on the LED semiconductor chip, and the LED semiconductor chip is used to support the fluorescent conversion layer; The LED semiconductor chip is at least one of a purple LED chip, a blue LED chip, and a red LED chip.

12. The LED light source according to any one of claims 7 to 11, characterized in that: The LED light source is a fluorescence conversion type near-infrared LED device, which is used in the fields of biometric identification, sensing, food detection, medical detection, temperature measurement, agricultural production or biological imaging.

13. The method for preparing an LED light source according to any one of claims 7 to 11, characterized in that: The preparation method comprises the following steps: mixing the near-infrared luminescent material according to any one of claims 1 to 3 and / or the near-infrared luminescent material obtained by the preparation method according to claim 4 with glue, and then coating the mixture on an LED semiconductor chip.

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