CN114958366A - Broadband near-infrared luminescent material and preparation method and application thereof - Google Patents

Abstract

The invention discloses a broadband near-infrared light-emitting material and a preparation method and application thereof. The chemical composition of the near-infrared light-emitting material is Mg _2-x Zn _x SnO ₄ : y%Cr ³⁺ , z%M; wherein, M is Eu ³⁺ , Tb ³⁺ , Sm ³⁺ , Pr ³⁺ , Yb ³ Any combination of one or more of ⁺ . The near-infrared luminescent material of the present invention can generate broadband near-infrared light with an emission peak at 600-1200 nanometers and a half-peak width of 180 nanometers under the excitation of ultraviolet-visible light with a wavelength of 250-700 nanometers; and can also be removed when the excitation light source is removed. Then, the near-infrared long afterglow emission with the afterglow time is much longer than 50 hours, and the afterglow emission peak is located at 800 nanometers. The near-infrared luminescent material of the invention has high photoelectric conversion efficiency, wide half-peak width, and dual-mode luminescence, and can be widely used in the fields of human vein imaging, night vision illumination, food detection, biomedicine and the like.

Description

A kind of broadband near-infrared light-emitting material and its preparation method and application

technical field

The invention belongs to the technical field of luminescent materials, and in particular relates to a multifunctional broadband near-infrared luminescent material and a preparation method and application thereof.

Background technique

The near-infrared spectroscopy analysis technology using broadband near-infrared (650-2500 nanometer) luminescent materials as the light source can be applied to emerging technologies such as non-destructive testing, night vision recognition, and in vivo imaging. At present, commercial mature tungsten lamps and halogen lamps have problems such as high calorific value, short service life and inability to achieve miniaturization; near-infrared LED chips have narrow luminous range, low luminous efficiency and high cost. In contrast, the phosphor-converted light source using "visible light LED + near-infrared light-emitting material" has many advantages, such as high luminous efficiency, good stability, low cost and small size. To this end, researchers have developed a series of broadband near-infrared light-emitting materials and their light-emitting devices, such as the published Chinese invention patents CN111117618B, CN105802624B and non-patent literature (JY Zhong et al., Efficient Broadband Near-Infrared Emission in the GaTaO ₄ :Cr ³⁺ Phosphor, Advanced Optical Materials, 2021, 10, 2101800; DW et al., LiBA1F ₆ :Cr ³⁺ (B=Ca, Sr) fluoride phosphors with ultra-broadnear-infrared emission for NIR pc-LEDs, Ceramics International, 2022, 48, 387-396) et al. However, the current near-infrared light-emitting materials still have various problems, such as low photoelectric conversion efficiency, insufficient half-peak width, poor chemical stability, or the emission peak is limited to 700-800 nanometers. In addition, the near-infrared luminescence of these disclosed near-infrared luminescent materials can only be realized under continuous light irradiation, and the signal interference of autofluorescence in vivo cannot be completely excluded in the application of in vivo imaging, so that the signal-to-noise ratio is greatly reduced. affect the actual imaging effect. Obviously, the design and development of multifunctional broadband near-infrared light-emitting materials with high photoelectric conversion efficiency, large half-peak width, luminescence peak value greater than or equal to 800 nanometers, and long afterglow emission has important research significance and urgent practical needs.

SUMMARY OF THE INVENTION

In order to overcome the above shortcomings and deficiencies of the prior art, one of the objectives of the present invention is to provide a broadband near-infrared light-emitting material.

The near-infrared light-emitting material has dual-mode luminescence, which can generate broadband near-infrared light with an emission peak at 600-1200 nanometers and a half-peak width of 180 nanometers under the excitation of ultraviolet-visible light with a wavelength of 250-700 nanometers (photoinduced It is also possible to generate near-infrared long afterglow luminescence with an afterglow time much longer than 50 hours after removing the excitation light source, and the afterglow emission peak is located at 800 nanometers.

The second purpose of the present invention is to provide a method for preparing the above-mentioned broadband near-infrared light-emitting material.

The third object of the present invention is to provide the application of the above-mentioned broadband near-infrared light-emitting material.

The object of the present invention is achieved by at least one of the following technical solutions.

The invention provides a broadband near-infrared long afterglow material, the chemical composition of which is Mg _2-x Zn _x SnO ₄ : y%Cr ³⁺ , z%M; wherein, M is Eu ³⁺ , Tb ³⁺ , Sm ³⁺ Any combination of one or more of , Pr ³⁺ , Yb ³⁺ , the value ranges of x, y, and z are: 0≤x≤2.0, 0<y≤15.0, 0<z≤2.0.

Further, 0<y≤5.0, 0<z≤1.0.

The present invention also provides a method for preparing the above-mentioned broadband near-infrared light-emitting material, comprising the following steps:

(1) According to the stoichiometric ratio of each element in the light-emitting material whose chemical composition is Mg _2-x Zn _x SnO ₄ :y%Cr ³⁺ ,z%M Chromium compound and M-containing compound, and weigh a small amount of cosolvent, grind and mix evenly to obtain a mixed material;

(2) The mixed material in step (1) is calcined in a high-temperature furnace with a specific atmosphere to obtain a sintered body; cooled to room temperature, and ground into powder to obtain the powder of the broadband near-infrared light-emitting material.

Further, the magnesium-containing compound described in step (1) is selected from at least one of magnesium oxide, basic magnesium carbonate, magnesium carbonate, magnesium chloride, magnesium fluoride, magnesium sulfate, magnesium nitride, magnesium nitrate, magnesium acetate, and magnesium hydroxide. A sort of.

Preferably, the magnesium-containing compound in step (1) is magnesium oxide.

Further, the zinc-containing compound in step (1) is selected from at least one of zinc oxide, zinc chloride, zinc fluoride, zinc sulfate, zinc sulfide, zinc nitrate, and zinc acetate.

Preferably, the zinc-containing compound in step (1) is zinc oxide.

Further, the tin-containing compound in step (1) is selected from at least one of tin dioxide, stannous oxide, and tin acetate.

Preferably, the tin-containing compound in step (1) is tin dioxide.

Further, the chromium-containing compound in step (1) is selected from at least one of chromium trioxide, chromium chloride, chromium fluoride, chromium sulfate, and chromium nitrate.

Preferably, the tin-containing compound in step (1) is chromium trioxide.

Further, the M-containing compound in step (1) is selected from at least one of europium-containing compounds, terbium-containing compounds, samarium-containing compounds, praseodymium-containing compounds, and ytterbium-containing compounds.

Preferably, the M-containing compound in step (1) is a europium-containing compound.

Further preferably, the europium-containing compound described in step (1) is europium oxide.

Further, the cosolvent in step (1) is selected from lithium carbonate, lithium nitrate, lithium fluoride, sodium carbonate, sodium chloride, sodium fluoride, magnesium fluoride, magnesium chloride, aluminum fluoride, ammonium chloride, boric acid at least one of.

Preferably, the cosolvent in step (1) is lithium carbonate.

Further preferably, the amount of lithium carbonate used in step (1) is 0.1-10% of the total mass of the magnesium-containing compound, zinc-containing compound, tin-containing compound, chromium-containing compound and europium-containing compound.

Further, the calcination treatment temperature in step (2) is 1000-1600° C.; the calcination treatment time is 1-36 hours.

Further, the atmosphere described in step (2) is selected from at least one of air, oxygen, nitrogen, argon, a mixture of nitrogen and hydrogen, and a mixture of argon and hydrogen.

Preferably, the atmosphere described in step (2) is an air atmosphere.

The present invention further provides the application of the above-mentioned broadband near-infrared light-emitting material in a fluorescent conversion type LED device.

Further, the fluorescent conversion type LED device includes a light source and a fluorescent conversion layer; the fluorescent conversion layer includes the broadband near-infrared light-emitting material.

Further, the light source is selected from a laser diode, an organic electroluminescent device, and an LED chip with an emission wavelength between 300-700 nanometers.

Preferably, the LED chip is a blue LED chip of 400-500 nm or a red LED chip of 600-700 nm.

Further preferably, the LED chip is a blue LED chip of 400-500 nm.

Further, the fluorescence conversion layer is obtained by mixing and packaging the broadband near-infrared light-emitting material with an organic transparent resin and then curing.

Further, the organic transparent resin is selected from at least one of epoxy resin, silica gel, polymethyl methacrylate, and polydimethylsiloxane.

Preferably, the organic transparent resin is epoxy resin.

The present invention further provides the application of the above-mentioned broadband near-infrared light-emitting material in the field of biotechnology.

Further, utilizing the near-infrared long afterglow luminescence properties of the near-infrared luminescent material, the broadband near-infrared luminescent material is used in the field of biological imaging as a fluorescent probe with no background autofluorescence interference and high tissue penetration depth.

Further, the near-infrared luminescent material is irradiated under an excitation light source for five minutes in advance and then turned off as a fluorescent labeling material for near-infrared biological optical imaging.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

(1) Compared with other near-infrared light-emitting materials using precious elements such as Ga, Ge, In, and Sc, the Sn element used in the present invention is inexpensive, and the preparation process is simple, efficient, and easy to control, and is suitable for large-scale promotion of practical applications. .

(2) The near-infrared luminescent material provided by the present invention has dual-mode luminescence, that is, near-infrared photoluminescence and long afterglow luminescence can be simultaneously realized in a single matrix, and can be more widely used in human vein imaging, night vision lighting, food detection, Security monitoring, biomedicine and many other fields can greatly reduce the cost of use and the research and development cost of new material systems.

(3) The near-infrared light-emitting material provided by the present invention has high photoelectric conversion efficiency, the half-peak width can reach 180 nanometers, and the light-emitting wavelength covers the range of 600-1200 nanometers. Significant application advantages.

(4) The afterglow emission peak of the near-infrared luminescent material provided by the present invention is located at 800 nanometers, which is greater than the emission wavelength of most of the currently reported long afterglow materials, and the afterglow time is much greater than 50 hours, which can achieve higher tissue penetration depth, Applications such as biomarker imaging for longer monitoring times.

Description of drawings

FIG. 1 is the X-ray powder diffraction pattern of the broadband near-infrared luminescent material prepared by the ratios (1)-(6) in Example 1.

FIG. 2 is the excitation and emission spectra of the broadband near-infrared luminescent material prepared in the ratio (5) in Example 1. FIG.

FIG. 3 is the emission spectrum of the broadband near-infrared luminescent material prepared by the ratio (5) in Example 1 under excitation at different wavelengths.

FIG. 4 is the fluorescence lifetime decay curve of the broadband near-infrared luminescent materials prepared in the ratios (1)-(6) in Example 1. FIG.

FIG. 5 is a photoluminescence spectrum and an integrated intensity curve diagram of the broadband near-infrared luminescent material prepared with the ratios (1)-(6) in Example 1. FIG.

FIG. 6 is the electroluminescence spectrum of the broadband near-infrared light-emitting device prepared in Example 7 and the device performance under different driving currents.

FIG. 7 is the afterglow emission spectrum of the broadband near-infrared luminescent material prepared in the ratio (2) in Example 8 under different spectrometer detector modes.

FIG. 8 is the afterglow emission spectrum of the broadband near-infrared luminescent material prepared in the ratio (2) in Example 8 under excitation at different wavelengths.

FIG. 9 is a graph of the afterglow decay curve and its integral intensity curve of the broadband near-infrared luminescent material prepared with the ratios (1)-(6) in Example 8. FIG.

FIG. 10 is the afterglow decay curve of the broadband near-infrared luminescent material prepared in the ratio (2) in Example 8 (recorded for 50 hours).

FIG. 11 is the thermoluminescence curve of the broadband near-infrared luminescent material prepared in the ratio (2) in Example 8 under different heating rates.

FIG. 12 is a photo-excited luminescence spectrum of the broadband near-infrared luminescent material prepared in the ratio (2) in Example 8. FIG.

13 is a graph of the afterglow decay curve and its integrated intensity curve of the broadband near-infrared light-emitting material prepared by co-doping Eu ³⁺ ions with different concentrations in Example 9.

Fig. 14 is a photoluminescence spectrum of the broadband near-infrared light-emitting materials prepared in Examples 10-19 and a histogram of their integrated intensity.

Detailed ways

The specific implementation of the present invention will be further described below with reference to examples, but the implementation and protection of the present invention are not limited thereto. It should be pointed out that, if there are any processes that are not described in detail below, those skilled in the art can realize or understand them with reference to the prior art. If the reagents or instruments used do not indicate the manufacturer, they are regarded as conventional products that can be purchased in the market.

Example 1

This embodiment provides a broadband near-infrared light-emitting material, the chemical composition of which is Mg ₂ SnO ₄ :y%Cr ³⁺ , y is the mole fraction, and 0<y≤5.0.

Magnesium oxide, tin dioxide, and chromium trioxide were selected as the starting compound raw materials, and the three kinds of compound raw materials were weighed according to the molar ratio of each element, a total of 6 groups, and the proportions were as follows:

(1) Mg:Sn:Cr=2:1:0.001, corresponding to y=0.1;

(2) Mg:Sn:Cr=2:1:0.003, corresponding to y=0.3;

(3) Mg:Sn:Cr=2:1:0.005, corresponding to y=0.5;

(4) Mg:Sn:Cr=2:1:0.010, corresponding to y=1.0;

(5) Mg:Sn:Cr=2:1:0.030, corresponding to y=3.0;

(6) Mg:Sn:Cr=2:1:0.050, corresponding to y=5.0

After the mixture is ground and mixed (the time of grinding and mixing is more than 5 minutes), it is put into a corundum crucible, and then the crucible is placed in a corundum porcelain boat, put into a high-temperature box-type electric furnace, and the heating rate is strictly controlled, and the heating rate is 5 ℃/min, calcined at 1500 ℃ for 5 hours in an air atmosphere, cooled to room temperature, and ground into powder to obtain the broadband near-infrared light-emitting material designed above.

FIG. 1 is the X-ray powder diffraction pattern of the broadband near-infrared luminescent material prepared by the ratios (1)-(6) in Example 1. XRD pattern analysis shows that the prepared samples are all pure Mg ₂ SnO ₄ phase, belonging to the cubic crystal system, and Cr ³⁺ doping does not introduce other phases or impurities.

FIG. 2 is the excitation and emission spectra of the broadband near-infrared luminescent material prepared in the ratio (5) in Example 1. FIG. Under the excitation of 467 nm wavelength, the material can obtain broadband near-infrared luminescence covering the range of ^600-1200 nm, and the half-peak width reaches 180 nm. This broadband emission is derived from ⁴ T ₂ → ⁴ A ₂ ( ⁴ F) Transition. By monitoring the emission wavelength at 800 nanometers, the excitation spectrum of the material can be found to cover the UV-NIR wavelength range.

It can be seen from Figure 3 that the material can obtain broadband near-infrared luminescence under excitation at 467 and 622 nm wavelengths, indicating that the material can be packaged together with blue and red LED chips into efficient fluorescence conversion LED devices.

FIG. 4 shows the fluorescence lifetime decay curve of the broadband near-infrared light-emitting materials prepared in the ratios (1)-(6) in Example 1. It can be seen that the fluorescence lifetimes of all samples are in the microsecond level, further indicating that the broadband emission of this material is from the ⁴ T ₂ → ⁴ A ₂ ( ⁴ F) spin-allowed transition of Cr ³⁺ ions.

It can be seen from Figure 5 that the broadband near-infrared luminescent materials prepared with different ratios can produce high-efficiency broadband near-infrared luminescence under the excitation of 467 nm wavelength, and the photoluminescence intensity varies with the content of Cr ³⁺ ions. However, when y=3.0, the photoluminescence of the material is the strongest.

Example 2-5

Embodiment 2-5 provides a broadband near-infrared light-emitting material, the chemical composition of which is Mg ₂ SnO ₄ :y%Cr ³⁺ , y is the mole fraction, and 0<y≤5.0.

The preparation methods of the broadband near-infrared light-emitting materials provided in Examples 2-5 are the same as those in Example 1 except that the temperature and time parameters of the calcination treatment are different. Among them, the calcination treatment parameters of Example 2 are 1500°C, 10 hours, the calcination treatment parameters of Example 3 are 1400°C, 5 hours, the calcination treatment parameters of Example 4 are 1400°C, 12 hours, and the calcination treatment parameters of Example 5 The parameters are 1300°C, 15 hours. The excitation and emission spectra of the broadband near-infrared luminescent materials prepared in Examples 2-5 are the same as those in Example 1, and they can all generate high-efficiency broadband near-infrared luminescence under the excitation of 467 nm blue light, as shown in Figures 1-5.

Example 6

This embodiment provides a broadband near-infrared light-emitting material, the chemical composition of which is Mg ₂ SnO ₄ :y%Cr ³⁺ , y is the mole fraction, and 0<y≤5.0.

Other preparation steps and process conditions are the same as those in Example 1, except that 5 wt % of lithium carbonate is additionally added. The optical properties of the prepared broadband near-infrared light-emitting material are similar to those in Example 1, which can be referred to as shown in FIGS. 1-5 .

Example 7

This embodiment provides a fluorescence conversion broadband near-infrared light-emitting device, the device includes an LED chip and a fluorescence conversion layer, and the fluorescence conversion layer includes the broadband near-infrared light-emitting material described in Embodiments 1-6. The broadband near-infrared light-emitting material can effectively absorb the light emitted from the LED chip and convert it into efficient broadband near-infrared light.

As an example, the broadband near-infrared light-emitting material used in this embodiment is the broadband near-infrared light-emitting material prepared by the ratio (5) in Example 1 above, and its chemical composition is Mg ₂ SnO ₄ : 3.0% Cr ³⁺ ; The LED chip is a blue light InGaN semiconductor chip, and its emission wavelength is 460 nanometers. The broadband near-infrared light-emitting material is uniformly dispersed in the epoxy resin (the mass ratio of the broadband near-infrared light-emitting material to the epoxy resin is set to 1:1), and then it is covered on the LED chip by dispensing or coating, and the package is packaged. and welding the circuit to obtain the fluorescent conversion broadband near-infrared light-emitting device of the present invention.

As shown in a in Figure 6, the luminescence intensity of the blue light part of the fluorescence conversion broadband near-infrared light-emitting device is weak, mainly composed of the emission peak of the broadband near-infrared light-emitting material, which means that the device has a high photoelectric conversion efficiency. It can be seen from bc in Figure 6 that under different current driving, the luminous intensity of the device gradually increases and there is no intensity saturation phenomenon. The output power of the device is 188 mW under the driving current of 100 mA, and the photoelectric conversion The efficiency can reach 14%, which is obviously better than the performance of the fluorescence conversion broadband near-infrared light-emitting devices based on near-infrared light-emitting materials such as Ca ₃ Sc ₂ Si ₃ O ₁₂ : Cr ³⁺ and GaTaO ₄ : Cr ³⁺ .

Example 8

The present embodiment provides a broadband near-infrared light-emitting material with near-infrared long afterglow emission characteristics, the chemical composition of which is Mg ₂ SnO ₄ :y%Cr ³⁺ , y is the mole fraction, and 0<y≤5.0.

Except that the calcination treatment time was changed to 8 hours, other preparation steps and process conditions were the same as those in Example 1.

FIG. 7 is the afterglow emission spectrum of the broadband near-infrared luminescent material prepared in the ratio (2) in Example 8 under different spectrometer detector modes. In addition to photoluminescence, the material exhibits remarkable near-infrared long afterglow luminescence after removing the excitation light source. It can be seen that the peak shape and luminescence peak position of the afterglow emission spectrum of this material are consistent with its photoluminescence emission spectrum, indicating that its long afterglow emission also comes from ⁴ T ₂ → ⁴ A ₂ ( ⁴ Cr ³⁺ ions. F) Transition.

As shown in Figure 8, the material can produce obvious near-infrared long afterglow luminescence after pre-excitation with different wavelengths of ultraviolet light.

As shown in Figure 9, the results of the afterglow decay curves of the broadband near-infrared luminescent materials prepared with different ratios show that the long afterglow luminescence performance of the material is the best when y=0.3.

Further, as shown in Figure 10, when the ultraviolet lamp irradiation is stopped, the near-infrared long afterglow luminescence of the broadband near-infrared luminescent material prepared by the ratio (2) still has a high long afterglow after 50 hours of decay. The luminescence signal indicates that the afterglow time is much greater than 50 hours.

FIG. 11 is the thermoluminescence curve of the broadband near-infrared luminescent material prepared in the ratio (2) in Example 8 under different heating rates. According to the Hoogenstraaten method, after linear fitting, the trap depth of the prepared sample is 0.709 eV, which is between 0.6-0.9 eV, indicating that the trap with suitable depth in this material is capable of producing ultra-long afterglow at room temperature an important reason for time.

As can be seen from Figure 12, the material also exhibits significant photo-excited luminescence properties, which can be clearly seen after the sample decays over a period of time (for example, 2 hours) and is irradiated by a red LED or an 808 nm laser for 30 seconds The enhancement is beneficial for long-term in vivo imaging marker tracking.

Example 9

This embodiment provides a broadband near-infrared light-emitting material with near-infrared long afterglow emission characteristics, the chemical composition of which is Mg ₂ SnO ₄ : 0.3%Cr ³⁺ , zEu ³⁺ , z is the mole fraction, and 0<z≤1.0 .

Except for adding different concentrations of Eu ³⁺ ions, other preparation steps and process conditions are the same as those in Example 1.

As shown in Figure 13, after co-doping Eu ³⁺ ions, the afterglow luminescence performance of the material can be significantly improved; when the doping amount of Eu ³⁺ ions is 0.5%, the afterglow luminescence performance of the material can be improved by 1.6% times.

Examples 10-19

Embodiments 10-19 provide a broadband near-infrared light-emitting material, the chemical composition of which is Mg _2-x Zn _x SnO ₄ :y%Cr ³⁺ , and 0≤x≤2.0, 0<y≤5.0.

The preparation method of the broadband near-infrared light-emitting material in each embodiment is the same as the preparation method of Example 1. It is only necessary to weigh the raw materials according to the stoichiometric ratio of each element in the broadband near-infrared light-emitting material of each embodiment, and carry out mixing, grinding and calcination. , that is, the broadband near-infrared light-emitting material is prepared.

The luminescence properties of the broadband near-infrared luminescent materials prepared in the ratio (5) in each example were characterized, and the results are shown in Table 1 below.

It can be seen from Fig. 14 that the use of Zn element to partially replace Mg element can realize a great control of the luminescent properties of the material; when the substitution amount of Zn element is x=0.8, the broadband near-infrared luminescent material has the best performance Compared with Example 1, its photoluminescence intensity can be improved by 2.6 times.

Table 1 Relative luminescence intensity of broadband near-infrared luminescent materials under excitation at 467 nm

Example chemical components Luminescence peak position relative luminous intensity Example 1 Mg₂SnO₄:3.0%Cr³⁺ 800nm 100 Example 11 Mg_1.8Zn_0.2SnO₄:3.0%Cr³⁺ 801 nm 163 Example 12 Mg_1.6Zn_0.4SnO₄:3.0%Cr³⁺ 801 nm 208 Example 13 Mg_1.4Zn_0.6SnO₄:3.0%Cr³⁺ 799 nm 228 Example 14 Mg_1.2Zn_0.8SnO₄:3.0%Cr³⁺ 801 nm 260 Example 15 Mg_1.0Zn_1.0SnO₄:3.0%Cr³⁺ 802 nm 211 Example 16 Mg_0.8Zn_1.2SnO₄:3.0%Cr³⁺ 800nm 141 Example 17 Mg_0.5Zn_1.5SnO₄:3.0%Cr³⁺ 801 nm 101 Example 18 Mg_0.2Zn_1.8SnO₄:3.0%Cr³⁺ 799 nm 93 Example 19 Zn_2.0Sn_0.97Cr_0.03O₄:3.0％Cr³⁺ 800nm 41

The above examples are only preferred embodiments of the present invention, and are only used to explain the present invention, but not to limit the present invention. Changes, substitutions, modifications, etc. made by those skilled in the art without departing from the spirit of the present invention shall belong to the present invention. the scope of protection of the invention.

Claims (10)

1. The broadband near-infrared luminescent material is characterized in that the chemical composition of the luminescent material is Mg _2-x Zn _x SnO ₄ :y％Cr ³⁺ Z% M; wherein M is Eu ³⁺ 、Tb ³⁺ 、Sm ³⁺ 、Pr ³⁺ 、Yb ³⁺ In the formula (b), x, y and z are respectively in the following value ranges: x is more than or equal to 0 and less than or equal to 2.0, y is more than 0 and less than or equal to 15.0, and z is more than 0 and less than or equal to 2.0.

2. The broadband near-infrared luminescent material as claimed in claim 1, wherein the luminescent material generates broadband near-infrared light with an emission peak at 600-1200 nm and a half-peak width of 180 nm under the excitation of ultraviolet-visible light with a wavelength of 250-700 nm.

3. The broadband near-infrared luminescent material of claim 1, wherein the luminescent material generates near-infrared long-afterglow luminescence with afterglow time longer than 50 hours after removing the excitation light source, and the afterglow emission peak is at 800 nm.

4. A method for preparing the broadband near-infrared luminescent material according to any one of claims 1 to 3, comprising the steps of:

(1) according to chemical composition as Mg _2-x Zn _x SnO ₄ :y％Cr ³⁺ Weighing magnesium-containing compound, zinc-containing compound, tin-containing compound, chromium-containing compound and M-containing compound raw materials according to the stoichiometric ratio of each element in the z% M luminescent material, weighing a small amount of cosolvent, and grinding and uniformly mixing to obtain a mixed material;

(2) calcining the mixed material obtained in the step (1) in a high-temperature furnace filled with a specific atmosphere to obtain a sintered body; cooling to room temperature, and grinding into powder to obtain the powder of the broadband near-infrared luminescent material.

5. The production method according to claim 4, wherein in the step (1), the raw material is at least one selected from oxides, carbonates, fluorides, chlorides, sulfates, acetates, nitrates of magnesium, zinc, tin, chromium, and M element; in the step (1), the cosolvent is at least one selected from lithium carbonate, lithium nitrate, lithium fluoride, sodium carbonate, sodium chloride, sodium fluoride, magnesium chloride, aluminum fluoride, ammonium chloride and boric acid, and the proportion of the using amount of the cosolvent to the total weight of the raw materials is 0.1-10 wt%: 1; in the step (2), the calcining treatment temperature is 1000-1600 ℃, and the calcining treatment time is 1-36 hours; in the step (2), the atmosphere for calcination treatment is at least one selected from the group consisting of air, oxygen, nitrogen, argon, a mixture of nitrogen and hydrogen, and a mixture of argon and hydrogen.

6. Use of the broadband near-infrared luminescent material according to any one of claims 1 to 3, wherein the broadband near-infrared luminescent material is used in a fluorescence conversion type LED device.

7. The use according to claim 6, wherein the phosphor-converted LED device comprises a light source and a phosphor conversion layer; the fluorescence conversion layer comprises a broadband near-infrared luminescent material; the light source is selected from one of a laser diode, an organic electroluminescent device and an LED chip with the emission wavelength between 300 and 700 nanometers.

8. The application of claim 7, wherein the fluorescence conversion layer is obtained by mixing and encapsulating a broadband near-infrared luminescent material and an organic transparent resin and then curing; the organic transparent resin is at least one selected from epoxy resin, silica gel, polymethyl methacrylate and polydimethylsiloxane.

9. The application of the broadband near-infrared luminescent material as claimed in any one of claims 1 to 3, characterized in that the broadband near-infrared luminescent material is used as a fluorescent probe without background auto-fluorescence interference and with high tissue penetration depth in the field of biological imaging by utilizing the near-infrared long afterglow luminescent characteristics of the near-infrared luminescent material.

10. The use of claim 9, wherein the broadband near-infrared luminescent material is used as a fluorescent labeling material for near-infrared biological optical imaging after being irradiated under an excitation light source for five minutes in advance and then the excitation light source is turned off.

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