Mo 4+ / Sb 3+ / Br - Near-infrared fluorescent powder co-doped with Cs2ZrCl6 and preparation method and application thereof

Abstract

The application discloses a kind of Mo 4+ / Sb 3+ / Br ‑ Co-doped Cs2ZrCl6 Near-infrared fluorescent powder and its preparation method and application belong to inorganic optical functional material technical field.The chemical formula of the near-infrared fluorescent powder is 12%Mo 4+ / 3.6%Sb 3+ :Cs2Zr(Cl 0.46 Br 0.54 )6.The host of the near-infrared fluorescent powder is Cs2ZrCl6 vacancy ordered double perovskite structure, and the doping ions are uniformly distributed in the crystal lattice.The near-infrared fluorescent powder prepared in the application has strong broadband near-infrared emission at 920 nm band, which is derived from Mo 4+ .Sb 3+ and Br ‑ can effectively enhance the emission of Mo 4+ , and the fluorescent powder has high quantum efficiency and excellent thermal stability, and can realize efficient luminescence under the excitation of 450 nm blue LED chip, and is suitable for night vision lighting, infrared sensing, optical communication and other near-infrared optoelectronic devices.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of inorganic optical functional materials, and particularly relates to a Mo 4+ / Sb 3+ / Br - co-doped double perovskite structure Wide-band near-infrared fluorescent powder, a preparation method thereof and application of the wide-band near-infrared fluorescent powder in a near-infrared light-emitting device. BACKGROUND

[0002] Wide-band near-infrared (NIR) fluorescent materials have wide application prospects in the fields of night vision monitoring, infrared sensing, optical communication and the like. Traditional doped oxides or rare earth ion luminophores have defects such as harsh preparation conditions, low luminous efficiency or narrow emission wavelength. 4+ In recent years, lead-free halide fluorescent powders based on transition metal ions (such as Mo 4+ ) have attracted attention due to their high luminous efficiency, good bandwidth control ability and mild synthesis conditions.

[0003] However, Mo 4+ single-doped materials still face problems such as low excitation efficiency and poor thermal stability, which limit their practical device applications. Therefore, it is urgent to develop a new structure regulation strategy to improve the comprehensive performance of Mo 4+ / Sb 3+ / Br - co-doped fluorescent powders. SUMMARY

[0004] The purpose of the present application is to provide a Mo 4+ / Sb 3+ / Br - co-doped near-infrared fluorescent powder of Cs2ZrCl6, which has the characteristics of high luminous efficiency, good thermal stability, excitation wavelength adaptation to blue LED chips, and good controllability of preparation process and batch synthesis ability.

[0005] To achieve the above purpose, the present application provides the following technical solutions:

[0006] The present application provides a Mo 4+ / Sb 3+ / Br 0.46 co-doped near-infrared fluorescent powder of Cs2ZrCl6, which has the characteristics of high luminous efficiency, good thermal stability, excitation wavelength adaptation to blue LED chips, and good controllability of preparation process and batch synthesis ability. 0.54 The host of the near-infrared fluorescent powder is a Cs2ZrCl6 vacancy-ordered double perovskite structure, and the molar ratio of Br - to Cl - in the near-infrared fluorescent powder is 0.54:0.46, and the molar ratio of Mo 4+ to Sb3+ at a molar ratio of 10:3.

[0007] Further, the near-infrared fluorescent powder realizes broadband near-infrared emission of 800-1300 nm under 440-470 nm blue light excitation, and the emission main peak is located near 920 nm.

[0008] Further, the near-infrared fluorescent powder has an internal quantum efficiency (IQE) ≥ 87% and an external quantum efficiency (EQE) ≥ 52% under 450 nm excitation, and retains ≥ 88% of room temperature luminescence intensity at 420 K.

[0009] The application further provides the Mo 4+ / Sb 3+ / Br - Preparation method of the near-infrared fluorescent powder co-doped with Cs2ZrCl6, comprising the following steps:

[0010] (1) according to the chemical formula 12%Mo 4+ / 3.6%Sb 3+ :Cs2Zr(Cl 0.46 Br 0.54 )6, respectively, CsCl, ZrCl4, MoCl5, SbCl3, HBr and HCl are weighed according to the stoichiometric ratio;

[0011] (2) HBr and HCl are mixed according to a molar ratio of 0.54:0.46 to obtain a first acidic solution;

[0012] (3) CsCl is dissolved in part of the first acidic solution to obtain a first precursor solution;

[0013] (4) ZrCl4, MoCl5 and SbCl3 are dissolved in the remaining first acidic solution to obtain a second precursor solution;

[0014] (5) the first precursor solution and the second precursor solution are rapidly mixed at room temperature for ≤ 10s to form a precipitate;

[0015] (6) after centrifugation and anhydrous ethanol washing, drying is performed to obtain the near-infrared fluorescent powder.

[0016] The application further provides the Mo 4+ / Sb 3+ / Br - Application of the near-infrared fluorescent powder co-doped with Cs2ZrCl6 in preparation of a near-infrared LED.

[0017] Further, the application comprises: encapsulating the near-infrared fluorescent powder on the blue light LED chip through PDMS. The blue light LED chip adopts a 440-470 nm LED chip.

[0018] Further preferably, the blue light LED chip adopts a 450 nm LED chip.

[0019] The application has the following beneficial effects:

[0020] The application adopts Mo 4+ , Sb 3+ as co-doped ions, Br - as an anion substitutional doping element, adopts a vacancy-ordered double perovskite Cs2ZrCl6 as a luminescent matrix, has low toxicity, high symmetry and good structural stability, and utilizes the vacancy-ordered structure of Cs2ZrCl6 to inhibit non-radiative transition. By synergistically introducing Mo 4+ , Sb 3+ and Br - three kinds of doping elements, electronic structure regulation, energy band engineering and lattice distortion synergistic regulation are realized. Mo 4+ as a d-electron configuration luminescent center, gives the material strong d-d emission in the near-infrared region (920 nm); Sb 3+ can effectively improve the energy transfer efficiency of the system; Br - substitutes Cl - causes lattice softening and spin-orbit coupling enhancement, further improves the stability of the excited state and the radiation transition probability. The near-infrared fluorescent powder prepared by the application has strong broadband near-infrared emission at 920 nm, which is derived from Mo 4+ ; Sb 3+ and Br - can effectively enhance the emission of Mo 4+ , the fluorescent powder has high quantum efficiency and excellent thermal stability, can realize high-efficiency luminescence under the excitation of a 450 nm blue light LED chip, and is suitable for use in near-infrared optoelectronic devices such as night vision lighting, infrared sensing and optical communication. The results of the embodiments show that the internal quantum efficiency of the material at room temperature is as high as 92.4%, the external quantum efficiency is as high as 65.9%, and the luminescence intensity remains 88.2% at 420K without obvious thermal quenching. At the same time, the material is prepared by a simple room temperature co-precipitation method, and the experimental raw materials are environmentally friendly. The preparation process is simple, the experimental operation is simple, the material can be prepared in large quantities, and is suitable for industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is the emission spectrum diagram of SM-CZC prepared in Example 1 under 450 nm excitation.

[0022] Figure 2This is the excitation spectrum of SM-CZC prepared in Example 1, detected at 920 nm.

[0023] Figure 3 The image shows the XRD pattern of SM-CZC and its matrix material Cs2ZrCl6 prepared in Example 1.

[0024] Figure 4 This is a graph showing the change in PL intensity of SM-CZC prepared in Example 1 at different temperatures.

[0025] Figure 5 This is the emission spectrum of a near-infrared LED device based on SM-CZC under different driving currents.

[0026] Figure 6 These are optical photographs of the SM-CZC and near-infrared LED devices prepared in Example 1 during operation.

[0027] Figure 7 The graph shows the internal and external quantum efficiency of the SM-CZC prepared in Example 1 under 450 nm excitation.

[0028] Figure 8 It’s x%Mo 4+ Emission spectrum of Cs2ZrCl6 under 365 nm excitation.

[0029] Figure 9 It’s 12%Mo 4+ / 3.6%Sb 3+ :Cs2Zr(Cl 0.46 Br 0.54 ) 6、 12%Mo 4+ :Cs2ZrCl 6、 3.6%Sb 3+ / 12%Mo 4+ :Cs2ZrCl6 and 12%Mo 4+ :Cs2Zr(Cl 0.46 Br 0.54 6. Excitation and emission spectra of four near-infrared phosphors.

[0030] Figure 10 It’s 12%Mo 4+ :Cs2ZrCl6、3.6%Sb 3+ / 12%Mo 4+ :Cs2ZrCl6 and 12%Mo 4+ / 3.6%Sb 3+ :Cs2Zr(Cl 0.46 Br 0.54 6. PL spectrum under 405nm laser excitation.

[0031] Figure 11 The graph shows the internal and external quantum efficiency of the SM-CZC prepared in Example 1 under 400 nm excitation.

[0032] Figure 12 It’s 12%Mo 4+ Density of states diagram of Cs2ZrCl6.

[0033] Figure 13 It is 3.6% Sb 3+ / 12%Mo 4+ Density of states diagram of Cs2ZrCl6.

[0034] Figure 14 It is 3.6%Te 4+ / 12%Mo 4+ Density of states diagram of Cs2ZrCl6.

[0035] Figure 15 It is 3.6% Sn 4+ / 12%Mo 4+ Density of states diagram of Cs2ZrCl6.

[0036] Figure 16 It is 3.6%Bi 3+ / 12%Mo 4+ Density of states diagram of Cs2ZrCl6. Detailed Implementation

[0037] Example 1

[0038] a kind of Mo 4+ / Sb 3+ / Br - Near-infrared phosphor co-doped with Cs₂ZrCl₆, with the chemical formula 12%Mo 4+ / 3.6%Sb 3+ :Cs2Zr(Cl 0.46 Br 0.54 6. Recorded as SM-CZC.

[0039] The above-mentioned Mo 4+ / Sb 3+ / Br - The preparation method of Cs₂ZrCl₆ co-doped near-infrared phosphor, the specific steps are as follows:

[0040] (1) Weigh out 10 mmol CsCl, 5 mmol ZrCl4, 0.6 mmol MoCl5, and 0.18 mmol SbCl3 according to the stoichiometric ratio, and take 10.8 mL of hydrobromic acid (0.2 mol HBr) and 9.2 mL of hydrochloric acid (0.17 mol HCl).

[0041] (2) HBr, HCl were mixed according to the molar ratio of 0.54:0.46 to obtain 20 mL of the first acidic solution;

[0042] (3) CsCl was dissolved in 5 mL of the first acidic solution to obtain the first precursor solution;

[0043] (4) ZrCl4, MoCl5 and SbCl3 were dissolved in the remaining 15 mL of the first acidic solution to obtain the second precursor solution;

[0044] (5) The first precursor solution was rapidly mixed with the second precursor solution at room temperature for 10 s to form a precipitate;

[0045] (6) The obtained precipitate was dried after centrifugation and ethanol washing to obtain the target product, denoted as SM-CZC.

[0046] The excitation and emission spectra of the SM-CZC of the present example are shown in Figure 1 and Figure 2 . Under 450 nm excitation, it shows broadband near-infrared emission in the range of 800-1300 nm, with an emission peak near 920 nm.

[0047] The XRD of the SM-CZC of the present example is shown in Figure 3 , which is consistent with the XRD of the matrix Cs2ZrCl6.

[0048] The SM-CZC of the present example has good thermal stability, and the luminescence intensity at 420 K can maintain more than 88% of that at room temperature, as shown in Figure 4 .

[0049] The SM-CZC of the present example was mixed uniformly with PDMS colloid and packaged on a blue LED chip to obtain a near-infrared LED. The blue LED chip can use a 440-470 nm LED chip. The EL under the drive of a 450 nm blue LED chip is shown in Figure 5 .

[0050] The near-infrared LED of the present application has no special limitation on the amount of SM-CZC, which can be changed according to actual needs.

[0051] The SM-CZC of the present example has excellent luminous efficiency, as shown in Figure 7 . Under 450 nm excitation, the internal quantum efficiency (IQE) is more than 87%, and the external quantum efficiency (EQE) is more than 52%. The polytetrafluoroethylene whiteboard was used as a blank control group, the integral emission range was 800-1100 nm, and the excitation range was 440-460 nm. In the present example, Sb 3+ and Mo 4+charge mismatching, will lead to Mo 5+ - Br 5+ generation, as shown in Figure 10 . In addition, under 400 nm excitation, the IQE is over 92%, and the EQE is over 65%, as shown in Figure 11 .

[0052] Comparative Example 1

[0053] A Mo 4+ doped Cs2ZrCl6 near-infrared fluorescent powder, whose chemical formula is x%Mo 4+ :Cs2ZrCl6, wherein x = 1, 5, 8, 10, 12, 15, 20.

[0054] The above-mentioned Mo 4+ doped Cs2ZrCl6 near-infrared fluorescent powder is prepared by the following steps:

[0055] (1) 10 mmol of CsCl and 5 mmol of ZrCl4, are weighed according to the measured proportion, and 20 mL of hydrochloric acid is taken;

[0056] (2) The CsCl is dissolved in 5 mL of hydrochloric acid to obtain a first precursor solution;

[0057] (4) ZrCl4 and MoCl5 are dissolved in 15 mL of hydrochloric acid to obtain a second precursor solution;

[0058] (5) The first precursor solution and the second precursor solution are rapidly mixed at room temperature for 10 s to form a precipitate;

[0059] (6) The obtained precipitate is centrifuged, washed with anhydrous ethanol, and dried to obtain the target product.

[0060] The emission spectrum of Comparative Example 1 is shown in Figure 8 . Under 365 nm excitation, it shows broadband near-infrared emission in the range of 800-1300 nm, with an emission peak near 920 nm, wherein 12%Mo 4+ :Cs2ZrCl6 has the strongest luminescence, but the luminescence is much weaker than that of SM-CZCB. The density of states of Comparative Example 1 is shown in Figure 12 . At this time, the [ZrCl6] 2- energy level is far from the [MoCl6] 2- energy level. In this case, the energy transfer efficiency of [ZrCl6] 2- and [MoCl6] 2- is very low, so the luminescence is weak.

[0061] ​Comparative Example 2

[0062] A Mo 4+ / Sb 3+ Near-infrared fluorescent powder co-doped with Cs2ZrCl6, with a chemical formula of 3.6%Sb 3+ / 12%Mo 4+ :Cs2ZrCl6.

[0063] The above Mo 4+ / Sb 3+ Method for preparing near-infrared fluorescent powder co-doped with Cs2ZrCl6, the specific steps are as follows:

[0064] (1) 10 mmol of CsCl, 5 mmol of ZrCl4, 0.6 mmol of MoCl5, and 0.18 mmol of SbCl3 were weighed according to the measured proportion, and 20 mL of hydrochloric acid was taken;

[0065] (2) CsCl was dissolved in 5 mL of hydrochloric acid to obtain a first precursor solution;

[0066] (4) ZrCl4, MoCl5, and SbCl3 were dissolved in 15 mL of hydrochloric acid to obtain a second precursor solution;

[0067] (5) The first precursor solution and the second precursor solution were rapidly mixed at room temperature for 10 s to form a precipitate;

[0068] (6) The obtained precipitate was centrifuged, washed with anhydrous ethanol, and dried to obtain the target product.

[0069] The emission spectrum of Comparative Example 2 is shown in Figure 9 . Under 365 nm excitation, it shows broadband near-infrared emission in the range of 800-1300 nm, with an emission peak near 920 nm, but the luminescence is much weaker than that of SM-CZCB. The density of states of Comparative Example 2 is shown in Figure 13 . The introduction of Sb 3+ modulates the band structure, promotes the [ZrCl6] 2- energy level to be closer to the [MoCl6] 2- energy level, significantly improves the energy transfer efficiency, and the luminescence is stronger than that of Comparative Example 1.

[0070] Comparative Example 3

[0071] A Mo 4+ / Br - Near-infrared fluorescent powder co-doped with Cs2ZrCl6, with a chemical formula of 12%Mo 4+ :Cs2Zr(Cl 0.46 Br 0.54 )6.

[0072] The above-mentioned Mo 4+ / Br - The preparation method of the near-infrared fluorescent powder co-doped with Cs2ZrCl6 is specifically as follows:

[0073] (1) 10 mmol of CsCl, 5 mmol of ZrCl4, and 0.6 mmol of MoCl5 were weighed according to the measured proportion, and 10.8 mL of hydrobromic acid (0.2 mol of HBr) and 9.2 mL of hydrochloric acid (0.17 mol of HCl) were taken;

[0074] (2) The HBr and HCl were mixed according to a molar ratio of 0.54:0.46 to obtain 20 mL of a first acidic solution;

[0075] (3) The CsCl was dissolved in 5 mL of the first acidic solution to obtain a first precursor solution;

[0076] (4) The ZrCl4 and MoCl5 were dissolved in 15 mL of the first acidic solution to obtain a second precursor solution;

[0077] (5) The first precursor solution and the second precursor solution were rapidly mixed at room temperature for 10 s to form a precipitate;

[0078] (6) The obtained precipitate was centrifuged, washed with anhydrous ethanol, and dried to obtain the target product.

[0079] The excitation and emission spectra of the comparative example 3 are shown in Figure 9 . Under 450 nm excitation, broadband near-infrared emission in the range of 800-1300 nm was exhibited, and the emission peak was located near 920 nm, but the luminescence was much weaker than that of SM-CZCB.

[0080] Comparative example 4

[0081] The above-mentioned Mo 4+ / Te 4+ The near-infrared fluorescent powder co-doped with Cs2ZrCl6 has a chemical formula of 3.6% Te 4+ / 12%Mo 4+ :Cs2ZrCl6.

[0082] The above-mentioned Mo 4+ / Te 4+ The preparation method of the near-infrared fluorescent powder co-doped with Cs2ZrCl6 is specifically as follows:

[0083] (1) 10 mmol of CsCl, 5 mmol of ZrCl4, and 0.6 mmol of MoCl5 were weighed according to the measured proportion, and 10.8 mL of hydrobromic acid (0.2 mol of HBr) and 9.2 mL of hydrochloric acid (0.17 mol of HCl) were taken;

[0084] (2) Dissolve CsCl in 5 mL of hydrochloric acid to obtain the first precursor solution;

[0085] (4) Dissolve ZrCl4, MoCl5, and TeCl4 in 15 mL of hydrochloric acid to obtain a second precursor solution;

[0086] (5) The first precursor solution and the second precursor solution are rapidly mixed at room temperature for 10 seconds to form a precipitate;

[0087] (6) The precipitate was centrifuged, washed with anhydrous ethanol and dried to obtain the target product.

[0088] The density of states calculation diagram for Comparative Example 4 is shown below. Figure 14 As shown, Te 4+ After addition, [ZrCl6] 2- It makes a significant contribution to the bottom of the conduction band, while [MoCl6] 2- Its contribution is relatively low; some energy is used by [ZrCl6]. 2- Consumption prevents efficient energy transfer. 4+ Its effect is far weaker than Sb 3+ .

[0089] Comparative Example 5

[0090] a kind of Mo 4+ / Sn 4+ Near-infrared phosphor co-doped with Cs₂ZrCl₆, with the chemical formula 3.6% Sn 4+ / 12%Mo 4+ :Cs2ZrCl6.

[0091] The above-mentioned Mo 4+ / Sn 4+ The preparation method of Cs₂ZrCl₆ co-doped near-infrared phosphor, the specific steps are as follows:

[0092] (1) Weigh out 10 mmol CsCl, 5 mmol ZrCl4, 0.6 mmol MoCl5, and 0.18 mmol SnCl4 according to the measurement ratio, and take 20 mL of hydrochloric acid;

[0093] (2) Dissolve CsCl in 5 mL of hydrochloric acid to obtain the first precursor solution;

[0094] (4) Dissolve ZrCl4, MoCl5 and SnCl4 in 15 mL of hydrochloric acid to obtain the second precursor solution;

[0095] (5) The first precursor solution and the second precursor solution are rapidly mixed at room temperature for 10 seconds to form a precipitate;

[0096] (6) The precipitate was centrifuged, washed with anhydrous ethanol and dried to obtain the target product.

[0097] The density of states calculation diagram of Comparative Example 5 is shown below. Figure 15 As shown, Sn 4+ After addition, [ZrCl6] 2- It makes a significant contribution to the bottom of the conduction band, while [MoCl6] 2- Its contribution is relatively low; some energy is used by [ZrCl6]. 2- Consumption prevents efficient energy transfer. Sn 4+ Its effect is far weaker than Sb 3+ .

[0098] Comparative Example 6

[0099] a kind of Mo 4+ / Bi 3+ Near-infrared phosphor co-doped with Cs₂ZrCl₆, with the chemical formula 3.6% Bi 3+ / 12%Mo 4+ :Cs2ZrCl6.

[0100] The above-mentioned Mo 4+ / Bi 3+ The preparation method of Cs₂ZrCl₆ co-doped near-infrared phosphor, the specific steps are as follows:

[0101] (1) Weigh out 10 mmol CsCl, 5 mmol ZrCl4, 0.6 mmol MoCl5, and 0.18 mmol BiCl3 according to the measurement ratio, and take 20 mL of hydrochloric acid;

[0102] (2) Dissolve CsCl in 5 mL of hydrochloric acid to obtain the first precursor solution;

[0103] (4) Dissolve ZrCl4, MoCl5, and BiCl3 in 15 mL of hydrochloric acid to obtain the second precursor solution;

[0104] (5) The first precursor solution and the second precursor solution are rapidly mixed at room temperature for 10 seconds to form a precipitate;

[0105] (6) The precipitate was centrifuged, washed with anhydrous ethanol and dried to obtain the target product.

[0106] The density of states calculation diagram for Comparative Example 6 is shown below. Figure 16 As shown, Bi 3+ It cannot make [ZrCl6] 2- The energy level decreases, and the distance from [MoCl6] is... 2- Too far to achieve effective energy transfer.3+ The effect of Sb is much weaker than Sb 3+ .

[0107] The present application realizes the synergistic control of electronic structure, energy band engineering and lattice distortion by synergistically introducing Mo 4+ , Sb 3+ and Br - three doping elements to form a ternary synergistic doping system. The present application innovatively introduces , which plays a role of sensitization and improves luminescence through the intermediate band control of doping ions, and it plays a "bridge role": after introducing , the energy level is lowered by only 0.11 eV higher than , forming a nearly resonant energy level arrangement, significantly reducing the energy transfer barrier and improving the energy transfer efficiency, thereby greatly improving the near-infrared luminescence of the low-energy level (see Figure 9 , 12 , 13). The introduction of offsets the increase of defects and charge imbalance caused by Sb doping, thereby further stabilizing and enhancing the near-infrared luminescence of (see Figure 10 ), the near-infrared fluorescent powder of the present application also shows significant progress in photoluminescence efficiency: the internal quantum efficiency is greater than 92% under 400 nm excitation; the internal quantum efficiency is still greater than 87% under 450 nm excitation (see Figure 7 , 11 ), this significant leap in performance is directly due to the optimization of energy transfer mechanism brought by the synergistic energy band control of and . The present application has actually compared a variety of ions (such as of Comparative Example 4, of Comparative Example 5, of Comparative Example 6), the results show that only can effectively adjust the energy band and enhance energy transfer, and other ions cannot achieve similar effects (see Figures 14-16 ).

[0108] The above is only a preferred embodiment of the present application, but the present application is not limited to the above-described embodiments, and the scope of the present application cannot be limited by the above. Those skilled in the art can easily understand, implement and modify part or all of the processes of the above-described embodiments. Equivalent changes made in reliance on the claims of the present application still fall within the scope of the present application.

Claims

1. A Mo 4+ / Sb 3+ / Br - near-infrared fluorescent powder co-doped with Cs2ZrCl6, characterized in that, The chemical formula of the near-infrared fluorescent powder is 12%Mo 4+ / 3.6%Sb 3+ :Cs2Zr(Cl 0.46 Br 0.54 )6, the host of the near-infrared fluorescent powder is a vacancy-ordered double perovskite structure of Cs2ZrCl6, and the molar ratio of Br - to Cl - in the near-infrared fluorescent powder is 0.54:0.46, and the molar ratio of Mo 4+ to Sb 3+ is 10:

3.

2. A Mo 4+ / Sb 3+ / Br - The near-infrared fluorescent powder co-doped with Cs2ZrCl6 is characterized in that, The near-infrared fluorescent powder realizes broadband near-infrared emission of 800-1300 nm under 440-470 nm blue light excitation, and the emission main peak is located near 920 nm.

3. A Mo 4+ / Sb 3+ / Br - The near-infrared fluorescent powder co-doped with Cs2ZrCl6 is characterized in that, The near-infrared fluorescent powder has an internal quantum efficiency (IQE) ≥ 87% and an external quantum efficiency (EQE) ≥ 52% under 450 nm excitation, and retains ≥ 88% of the room temperature luminous intensity at 420 K.

4. A Mo 4+ / Sb 3+ / Br - A method for preparing a near-infrared fluorescent powder co-doped with Cs2ZrCl6, characterized in that, The method comprises the following steps: (1) 12% Mo according to the chemical formula 4+ / 3.6% Sb 3+ : Cs2Zr(Cl 0.46 Br 0.54 )6 CsCl, ZrCl4, MoCl5, SbCl3, HBr and HCl were weighed according to the stoichiometric ratio, respectively; (2) HBr and HCl are mixed in a molar ratio of 0.54:0.46 to obtain a first acidic solution; (3) CsCl is dissolved in part of the first acidic solution to obtain a first precursor solution; (4) ZrCl4, MoCl5 and SbCl3 are dissolved in the remaining first acidic solution to obtain a second precursor solution; (5) The first precursor solution and the second precursor solution are rapidly mixed at room temperature for ≤ 10 s to form a precipitate; (6) After centrifugation and anhydrous ethanol washing, drying is performed to obtain the near-infrared fluorescent powder.

5. A Mo of any one of claims 1-3 4+ / Sb 3+ / Br - A near-infrared fluorescent powder co-doped with Cs2ZrCl6 or a Mo prepared by the preparation method of claim 4 4+ / Sb 3+ / Br - Use of a near-infrared fluorescent powder co-doped with Cs2ZrCl6 in the preparation of a near-infrared LED.

6. Use according to claim 5, characterized in that, The near-infrared fluorescent powder is packaged on a blue light LED chip through PDMS.

7. Use according to claim 6, characterized in that, The blue light LED chip adopts an LED chip of 440-470 nm.

8. Use according to claim 7, characterized in that, The blue light LED chip adopts an LED chip of 450 nm.

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