Preparation method of all-inorganic vacancy ordered double perovskite luminescent material

Abstract

The invention discloses a preparation method of an all-inorganic vacancy ordered double perovskite luminescent material, and relates to the technical field of lead-free perovskite luminescent materials. The preparation method comprises the following steps: putting the raw materials CsCl and MoCl5 into a polytetrafluoroethylene lining, and mixing; then adding CeCl3 or TeO2, adding hydrochloric acid as a solvent, and stirring for one hour to fully and uniformly mix; and finally, putting the polytetrafluoroethylene lining into a cylinder sleeve of a reaction kettle, putting into a drying oven for reaction, slowly cooling to room temperature in the drying oven after the reaction is finished, cleaning with absolute ethyl alcohol, and drying to obtain the lead-free perovskite material. The prepared full-inorganic vacancy ordered double-perovskite luminescent material can emit broadband near-infrared light with the highest peak of about 990nm under the excitation of ultraviolet and blue light, and can be used in near-infrared imaging.

Description

Technical Field

[0001] The invention relates to the technical field of lead-free perovskite luminescent materials, and in particular to a method for preparing a fully inorganic vacancy ordered double perovskite luminescent material. Background Art

[0002] Broadband near infrared light sources (near infrared, NIR: ~700-1700nm) are invisible to the human eye, have a large penetration depth in living biological tissues, and do not damage the illuminated objects. Therefore, they have broad application prospects in food safety, security monitoring, medical diagnosis, information processing, optical communications, and non-invasive monitoring of human physiological status. For example, they can be used to prepare optical amplifiers, constitute an important component of optical fiber communications, and are used in industrial, medical, and military fields; near infrared spectra can be used for night vision detection and non-destructive imaging; this band contains characteristic absorption peaks of solvent molecules and can be used for high-sensitivity spectral measurement and analysis; near infrared light has a strong penetration depth into human tissue structures and can be used to detect the saturation of oxygenated hemoglobin in the brain and body; ultra-wideband, high-gain, and adjustable output power lasers can be constructed, which are expected to be integrated into the next generation 5G+6G Internet of Everything network.

[0003] Therefore, the development of broadband near-infrared luminescent materials has important academic research value and is the premise and basis for achieving widespread application. Compared with broadband emission sources in the near-infrared region I, efficient luminescent materials suitable for the near-infrared region II (NIR-Ⅱ: 1000-1700nm), especially materials with spectral characteristics of half-peak width greater than 200nm, are extremely scarce. At present, there are only a few materials containing Cr 3+ Cr 4+ 、Ni 2+ , Bi ions / clusters and Mn 2+ -Mn 2+ Ion-pair materials can achieve near-infrared second-zone broadband emission with a luminescence peak greater than 1000nm. However, these material systems generally have many problems such as high preparation cost, low luminescence efficiency, poor thermal stability, difficulty in regulating the luminescence peak, lack of systematic mechanism research and unclear luminescence mechanism, which seriously affect the practical application of near-infrared second-zone broadband emission light sources in many fields. According to the current reports on the photoluminescence quantum yield of the all-inorganic vacancy ordered double perovskite Cs2MoCl6, the photoluminescence quantum yield of this perovskite is at a relatively low level, so there is an urgent need for a method to improve the photoluminescence quantum yield.

[0004] Therefore, in order to solve the above technical problems, the present invention provides a method for preparing an all-inorganic vacancy ordered double perovskite luminescent material. Summary of the invention

[0005] The purpose of the present invention is to deeply study the method of enhancing near-infrared luminescence of Cs2MoCl6 perovskite doped with CeCl3 or TeO2; by changing the type of doping elements, the symmetry of Cs2MoCl6 perovskite is reduced, thereby respectively improving ultraviolet and blue light absorption, thereby improving the photoluminescence quantum yield; by adjusting the concentration of the dopant, under the same excitation conditions, the luminescence intensity of Cs2MoCl6 perovskite is increased to prepare a fully inorganic vacancy ordered double perovskite luminescent material.

[0006] In order to achieve the above technical effects, the present invention is implemented by the following technical solutions: A method for preparing an all-inorganic vacancy ordered double perovskite luminescent material, characterized in that it comprises the following steps:

[0007] S1, adding CsCl and MoCl5 in a molar ratio of CsCl:MoCl5=2-4:1-2 to a tetrafluoroethylene liner and mixing to obtain a mixture A;

[0008] S2. Add CeCl3 or TeO2 to mixture A to obtain a substrate, add hydrochloric acid to the substrate and stir thoroughly for 1 to 1.5 hours to mix well to obtain mixture B;

[0009] S3. Place mixture B in an oven at 160-200°C for 11-13 hours of heat preservation, then take it out and naturally cool it to room temperature, wash it with anhydrous ethanol 2-4 times, and dry it to obtain a fully inorganic vacancy ordered double perovskite luminescent material Cs2MoCl6.

[0010] Furthermore, in S2, the mass percentage of CeCl3 or TeO2 added is 1% to 10% of the total mass of CsCl and MoCl5.

[0011] Furthermore, in S2, the concentration of hydrochloric acid added is 37%, and the amount of hydrochloric acid added is 10 ml.

[0012] Furthermore, in S3, the reaction condition in the oven is 180° C. for 12 h.

[0013] Furthermore, in S3, drying includes placing the material into an oven, adjusting the temperature to 70-90° C., and drying for 11-13 hours.

[0014] Another object of the present invention is to provide an application of an all-inorganic vacancy ordered double perovskite luminescent material, characterized in that the all-inorganic vacancy ordered double perovskite luminescent material is applied in near-infrared imaging.

[0015] The beneficial effects of the present invention are:

[0016] (1) The present invention prepares Ce 3+Doping all-inorganic vacancy ordered double perovskite luminescent materials can enhance near-infrared luminescence under ultraviolet light excitation and improve the quantum yield of the material;

[0017] (2) The present invention prepares Te 4+ Doping all-inorganic vacancy ordered double perovskite luminescent materials can enhance near-infrared luminescence under blue light excitation and improve the quantum yield of the material;

[0018] (3) The perovskite matrix Cs2MoCl6 selected in the present invention has good structural stability and excellent optical properties;

[0019] (4) This article uses Ce 3+ and Te 4+ Doping Cs2MoCl6 all-inorganic vacancy ordered double perovskite can reduce the symmetry of the structure and enhance the ultraviolet and blue light absorption. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0021] Figure 1 This is a crystal structure diagram of the all-inorganic vacancy ordered double perovskite light-emitting material in Example 13 of the present invention;

[0022] Figure 2 The X-ray diffraction (XRD) data diagram of the all-inorganic vacancy ordered double perovskite luminescent material of each embodiment of the present invention;

[0023] Figure 3 For each embodiment, Ce is doped 3+ Scanning electron microscopy (SEM) of all-inorganic vacancy-ordered double perovskite luminescent materials.

[0024] Figure 4 For example, Te is doped 4+ Scanning electron microscopy (SEM) of all-inorganic vacancy-ordered double perovskite luminescent materials.

[0025] Figure 5 For example, Ce is doped 3+ Total spectrum of distribution map of all-inorganic vacancy-ordered double perovskite luminescent materials.

[0026] Figure 6 For example, Te is doped 4+ Total spectrum of distribution map of all-inorganic vacancy-ordered double perovskite luminescent materials.

[0027] Figure 7For example, Ce is doped 3+ Emission and excitation spectra of all-inorganic vacancy-ordered double perovskite luminescent materials

[0028] Figure 8 For example, Te is doped 4+ Emission and excitation spectra of all-inorganic vacancy-ordered double perovskite luminescent materials

[0029] Fig. 9 In the embodiment, Ce is doped 3+ The lead-free double perovskite material produces near-infrared quantum efficiency (PLQY) test under 375nm excitation.

[0030] Fig.10 In the embodiment, Te is doped 4+ The lead-free double perovskite material produces near-infrared quantum efficiency (PLQY) test under 375nm excitation. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] The ratio of the amount of CsCl and MoCl5 in the all-inorganic vacancy ordered double perovskite luminescent material prepared in this embodiment is CsCl:MoCl5=2:1, and the mass percentage of CeCl3 added is 1% of the total mass of CsCl and MoCl5. The specific preparation steps are as follows:

[0034] (1) CsCl and MoCl5 are added to a tetrafluoroethylene liner in a certain proportion to obtain a mixture A.

[0035] (2) Then, CeCl3 is added to the mixture A in step (1), and hydrochloric acid is added and stirred thoroughly to obtain a mixture B.

[0036] (3) Finally, the mixture B obtained in step (2) is placed in an oven at 180° C. for 12 h, cooled to room temperature, washed with anhydrous ethanol, and dried to obtain an all-inorganic vacancy ordered double perovskite luminescent material.

[0037] The emission intensity of the all-inorganic vacancy ordered double perovskite luminescent material obtained in this embodiment under 360nm excitation is as follows: Figure 7 shown.

[0038] Principle of the invention: Ce 3+ Ions and Te 4+ The energy level of the ions will interact with the energy level of Cs2MoCl6, thus showing good luminescence performance; in addition, Ce is introduced into the Cs2MoCl6 octahedral lattice. 3+ and Te 4+ , to reduce the symmetry of the structure and improve the crystal quality, so that the ultraviolet and blue light absorption ability of Cs2MoCl6 is improved, resulting in a higher photoluminescence quantum yield (PLQY).

[0039] Example 2

[0040] The ratio of the amount of CsCl and MoCl5 in the all-inorganic vacancy ordered double perovskite luminescent material prepared in this embodiment is CsCl:MoCl5=2:1, and the mass percentage of CeCl3 added is 2% of the total mass of CsCl and MoCl5. The specific preparation steps are as follows:

[0041] (1) CsCl and MoCl5 are added to a tetrafluoroethylene liner in a certain proportion to obtain a mixture A.

[0042] (2) Then, CeCl3 is added to the mixture A in step (1), and hydrochloric acid is added and stirred thoroughly to obtain a mixture B.

[0043] (3) Finally, the mixture B obtained in step (2) is placed in an oven at 180° C. for 12 h, cooled to room temperature, washed with anhydrous ethanol, and dried to obtain an all-inorganic vacancy ordered double perovskite luminescent material.

[0044] The emission intensity of the all-inorganic vacancy ordered double perovskite luminescent material obtained in this embodiment under 360nm excitation is as follows: Figure 7 shown.

[0045] Example 3

[0046] The ratio of the amount of CsCl and MoCl5 in the all-inorganic vacancy ordered double perovskite luminescent material prepared in this embodiment is CsCl:MoCl5=2:1, and the mass percentage of CeCl3 added is 4% of the total mass of CsCl and MoCl5. The specific preparation steps are as follows:

[0047] (1) CsCl and MoCl5 are added to a tetrafluoroethylene liner in a certain proportion and mixed to obtain a mixture A.

[0048] (2) Then, CeCl3 is added to the mixture A in step (1), and hydrochloric acid is added and stirred thoroughly to obtain a mixture B.

[0049] (3) Finally, the mixture B obtained in step (2) is placed in an oven at 180° C. for 12 h, cooled to room temperature, washed with anhydrous ethanol, and dried to obtain an all-inorganic vacancy ordered double perovskite luminescent material.

[0050] The emission intensity of the all-inorganic vacancy ordered double perovskite luminescent material obtained in this embodiment under 360nm excitation and the excitation spectrum were tested to obtain the best excitation at 375nm. Figure 7 As shown, by comparing XRD, it can be seen that the basic consistency with the matrix indicates that the sample was successfully synthesized. Figure 2 As shown by Figure 3 Scanning electron microscope Figure 5 Prove that the doped sample was successfully synthesized. Fig. 9 The near-infrared quantum efficiency successfully proved that the yield has been significantly improved. The above data support the discovery that the quantum yield has increased several times due to the reduction of the processivity of the structure itself, making the material easier to absorb ultraviolet light.

[0051] Example 4

[0052] The ratio of the amount of CsCl and MoCl5 in the all-inorganic vacancy ordered double perovskite luminescent material prepared in this embodiment is CsCl:MoCl5=2:1, and the mass percentage of CeCl3 added is 6% of the total mass of CsCl and MoCl5. The specific preparation steps are as follows:

[0053] (1) CsCl and MoCl5 are added to a tetrafluoroethylene liner in a certain proportion and mixed to obtain a mixture A.

[0054] (2) Then, CeCl3 is added to the mixture A in step (1), and hydrochloric acid is added and stirred thoroughly to obtain a mixture B.

[0055] (3) Finally, the mixture B obtained in step (2) is placed in an oven at 180° C. for 12 h, cooled to room temperature, washed with anhydrous ethanol, and dried to obtain an all-inorganic vacancy ordered double perovskite luminescent material.

[0056] The emission intensity of the all-inorganic vacancy ordered double perovskite luminescent material obtained in this embodiment under 360nm excitation is as follows: Figure 7 shown.

[0057] Example 5

[0058] The ratio of the amount of CsCl and MoCl5 in the all-inorganic vacancy ordered double perovskite luminescent material prepared in this embodiment is CsCl:MoCl5=2:1, and the mass percentage of CeCl3 added is 8% of the total mass of CsCl and MoCl5. The specific preparation steps are as follows:

[0059] (1) CsCl and MoCl5 are added to a tetrafluoroethylene liner in a certain proportion to obtain a mixture A.

[0060] (2) Then, CeCl3 is added to the mixture A in step (1), and hydrochloric acid is added and stirred thoroughly to obtain a mixture B.

[0061] (3) Finally, the mixture B obtained in step (2) is placed in an oven at 180° C. for 12 h, cooled to room temperature, washed with anhydrous ethanol, and dried to obtain an all-inorganic vacancy ordered double perovskite luminescent material.

[0062] The emission intensity of the all-inorganic vacancy ordered double perovskite luminescent material obtained in this embodiment under 360nm excitation is as follows: Figure 7 shown.

[0063] Example 6

[0064] The ratio of the amount of CsCl and MoCl5 in the all-inorganic vacancy ordered double perovskite luminescent material prepared in this embodiment is CsCl:MoCl5=2:1, and the mass percentage of CeCl3 added is 10% of the total mass of CsCl and MoCl5. The specific preparation steps are as follows:

[0065] (1) CsCl and MoCl5 are added to a tetrafluoroethylene liner in a certain proportion to obtain a mixture A.

[0066] (2) Then, CeCl3 is added to the mixture A in step (1), and hydrochloric acid is added and stirred thoroughly to obtain a mixture B.

[0067] (3) Finally, the mixture B obtained in step (2) is placed in an oven at 180° C. for 12 h, cooled to room temperature, washed with anhydrous ethanol, and dried to obtain an all-inorganic vacancy ordered double perovskite luminescent material.

[0068] The emission intensity of the all-inorganic vacancy ordered double perovskite luminescent material obtained in this embodiment under 360nm excitation is as follows: Figure 7 shown.

[0069] Example 7

[0070] The ratio of the amount of CsCl and MoCl5 in the all-inorganic vacancy ordered double perovskite luminescent material prepared in this embodiment is CsCl:MoCl5=2:1, and the mass percentage of TeO2 added is 1% of the total mass of CsCl and MoCl5. The specific preparation steps are as follows:

[0071] (1) CsCl and MoCl5 are added to a tetrafluoroethylene liner in a certain proportion to obtain a mixture A.

[0072] (2) Then, TeO2 is added to the mixture A in step (1), and hydrochloric acid is added and stirred thoroughly to obtain a mixture B.

[0073] (3) Finally, the mixture B obtained in step (2) is placed in an oven at 180° C. for 12 h, cooled to room temperature, washed with anhydrous ethanol, and dried to obtain an all-inorganic vacancy ordered double perovskite luminescent material.

[0074] The emission intensity of the all-inorganic vacancy ordered double perovskite luminescent material obtained in this embodiment under 360nm excitation is as follows: Figure 8 shown.

[0075] Example 8

[0076] The ratio of the amount of CsCl and MoCl5 in the all-inorganic vacancy ordered double perovskite luminescent material prepared in this embodiment is CsCl:MoCl5=2:1, and the mass percentage of TeO2 added is 2% of the total mass of CsCl and MoCl5. The specific preparation steps are as follows:

[0077] (1) CsCl and MoCl5 are added to a tetrafluoroethylene liner in a certain proportion to obtain a mixture A.

[0078] (2) Then, TeO2 is added to the mixture A in step (1), and hydrochloric acid is added and stirred thoroughly to obtain a mixture B.

[0079] (3) Finally, the mixture B obtained in step (2) is placed in an oven at 180° C. for 12 h, cooled to room temperature, washed with anhydrous ethanol, and dried to obtain an all-inorganic vacancy ordered double perovskite luminescent material.

[0080] The emission intensity of the all-inorganic vacancy ordered double perovskite luminescent material obtained in this embodiment under 360nm excitation is as follows: Figure 8 shown.

[0081] Example 9

[0082] The ratio of the amount of CsCl and MoCl5 in the all-inorganic vacancy ordered double perovskite luminescent material prepared in this embodiment is CsCl:MoCl5=2:1, and the mass percentage of TeO2 added is 4% of the total mass of CsCl and MoCl5. The specific preparation steps are as follows:

[0083] (1) CsCl and MoCl5 are added to a tetrafluoroethylene liner in a certain proportion to obtain a mixture A.

[0084] (2) Then, TeO2 is added to the mixture A in step (1), and hydrochloric acid is added and stirred thoroughly to obtain a mixture B.

[0085] (3) Finally, the mixture B obtained in step (2) is placed in an oven at 180° C. for 12 h, cooled to room temperature, washed with anhydrous ethanol, and dried to obtain an all-inorganic vacancy ordered double perovskite luminescent material.

[0086] The emission intensity of the all-inorganic vacancy ordered double perovskite luminescent material obtained in this embodiment under 360nm excitation is as follows: Figure 8 shown.

[0087] Example 10

[0088] The ratio of the amount of CsCl and MoCl5 in the all-inorganic vacancy ordered double perovskite luminescent material prepared in this embodiment is CsCl:MoCl5=2:1, and the mass percentage of TeO2 added is 6% of the total mass of CsCl and MoCl5. The specific preparation steps are as follows:

[0089] (1) CsCl and MoCl5 are added to a tetrafluoroethylene liner in a certain proportion and mixed to obtain a mixture A.

[0090] (2) Then, TeO2 is added to the mixture A in step (1), and hydrochloric acid is added and stirred thoroughly to obtain a mixture B.

[0091] (3) Finally, the mixture B obtained in step (2) is placed in an oven at 180° C. for 12 h, cooled to room temperature, washed with anhydrous ethanol, and dried to obtain an all-inorganic vacancy ordered double perovskite luminescent material.

[0092] The emission intensity of the all-inorganic vacancy ordered double perovskite luminescent material obtained in this embodiment under 360nm excitation is measured and the excitation spectrum is tested to obtain the best excitation spectra around 375nm and 460nm. Figure 8 As shown, by comparing the XRD pattern with the matrix, it is found that the doped TeO2 is basically consistent with the matrix. Figure 2 As shown by Figure 4 Scanning electron microscope Figure 6 Prove that the doped sample was successfully synthesized. Fig.10 The near-infrared quantum efficiency successfully proved that the yield has been improved. The above data support the discovery that the performance is improved by reducing the processivity of the structure itself, making the material easier to absorb blue light.

[0093] Embodiment 11

[0094] The molar ratio of MoCl5 is CsCl:MoCl5=2:1, and the mass percentage of TeO2 added is 8% of the total mass of CsCl and MoCl5. The specific preparation steps are as follows:

[0095] (1) CsCl and MoCl5 are added to a tetrafluoroethylene liner in a certain proportion to obtain a mixture A.

[0096] (2) Then, TeO2 is added to the mixture A in step (1), and hydrochloric acid is added and stirred thoroughly to obtain a mixture B.

[0097] (3) Finally, the mixture B obtained in step (2) is placed in an oven at 180° C. for 12 h, cooled to room temperature, washed with anhydrous ethanol, and dried to obtain an all-inorganic vacancy ordered double perovskite luminescent material.

[0098] The emission intensity of the all-inorganic vacancy ordered double perovskite luminescent material obtained in this embodiment under 360nm excitation is as follows: Figure 8 shown.

[0099] Example 12

[0100] The ratio of the amount of CsCl and MoCl5 in the all-inorganic vacancy ordered double perovskite luminescent material prepared in this embodiment is CsCl:MoCl5=2:1, and the mass percentage of TeO2 added is 10% of the total mass of CsCl and MoCl5. The specific preparation steps are as follows:

[0101] (1) CsCl and MoCl5 are added to a tetrafluoroethylene liner in a certain proportion to obtain a mixture A.

[0102] (2) Then, TeO2 is added to the mixture A in step (1), and hydrochloric acid is added and stirred thoroughly to obtain a mixture B.

[0103] (3) Finally, the mixture B obtained in step (2) is placed in an oven at 180° C. for 12 h, cooled to room temperature, washed with anhydrous ethanol, and dried to obtain an all-inorganic vacancy ordered double perovskite luminescent material.

[0104] The emission intensity of the all-inorganic vacancy ordered double perovskite luminescent material obtained in this embodiment under 360nm excitation is as follows: Figure 8 shown.

[0105] Example 13

[0106] For comparison, the present embodiment is different from the embodiment 1 in that CeCl3 or TeO2 is not doped, and the specific preparation steps are as follows:

[0107] (1) CsCl and ZrCl4 are added to a tetrafluoroethylene liner in a certain proportion and mixed to obtain a mixture A.

[0108] (2) Then, hydrochloric acid is added to the mixture A in step (1), and the mixture is stirred thoroughly to obtain a mixture B.

[0109] (3) Finally, the mixture B obtained in step (2) is placed in an oven and kept at 180° C. for 12 h. After cooling to room temperature, it is washed with anhydrous ethanol and dried to obtain a fully inorganic vacancy ordered double perovskite light-emitting material.

[0110] The crystal structure of the all-inorganic vacancy ordered double perovskite luminescent material obtained in this embodiment is shown in FIG. Figure 1 As shown, the XRD results are basically consistent with those of the standard card, indicating that the matrix is ​​successfully synthesized. According to known literature, the quantum yield of the material is only about 10%, which has a lot of room for improvement.

[0111] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects these embodiments to describe in detail in order to better explain the principles of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing an all-inorganic vacancy ordered double perovskite luminescent material, characterized in that: The following steps are involved: S1, adding CsCl and MoCl5 in a molar ratio of CsCl:MoCl5=2-4:1-2 to a tetrafluoroethylene liner and mixing to obtain a mixture A; S2. Add CeCl3 or TeO2 to mixture A to obtain a substrate, add hydrochloric acid to the substrate and stir thoroughly for 1 to 1.5 hours to mix well to obtain mixture B; S3. Place mixture B in an oven at 160-200°C for 11-13 hours of heat preservation, then take it out and naturally cool it to room temperature, wash it with anhydrous ethanol 2-4 times, and dry it to obtain a fully inorganic vacancy ordered double perovskite luminescent material Cs2MoCl6.

2. The method for preparing an all-inorganic vacancy ordered double perovskite luminescent material according to claim 1, characterized in that: In S2, the mass percentage of CeCl3 or TeO2 added is 1% to 10% of the total mass of CsCl and MoCl5.

3. The method for preparing an all-inorganic vacancy ordered double perovskite luminescent material according to claim 1, characterized in that: In S2, the concentration of hydrochloric acid added is 37%, and the amount of hydrochloric acid added is 10 ml.

4. The method for preparing an all-inorganic vacancy ordered double perovskite luminescent material according to claim 1, characterized in that: In S3, the reaction condition in the oven is 180°C for 12 h.

5. The method for preparing an all-inorganic vacancy ordered double perovskite luminescent material according to claim 1, characterized in that: In S3, drying includes placing the material in an oven, adjusting the temperature to 70 to 90° C., and drying for 11 to 13 hours.

6. The use of the all-inorganic vacancy ordered double perovskite luminescent material according to any one of claims 1 to 5, characterized in that: The all-inorganic vacancy ordered double perovskite luminescent material is used in near-infrared imaging.

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