A double perovskite-based luminescent material, a preparation method thereof and application thereof in luminescent imaging or anti-counterfeiting

Abstract

The application belongs to the technical field of detection materials, and relates to a double-perovskite-based luminescent material, a preparation method thereof and application of the double-perovskite-based luminescent material in luminescent imaging or anti-counterfeiting. 3+ / Yb 3+ The molar doping concentration of Tm 3+ is 0.5-5%, and the molar doping concentration of Yb 3+ is 2%-80%. The preparation method is as follows: cesium chloride, sodium chloride, chromium chloride, thulium chloride and ytterbium chloride are dissolved in water according to the stoichiometric ratio, uniformly mixed and subjected to a solution synthesis reaction, and then the solvent is evaporated to obtain the double-perovskite-based luminescent material. The double-perovskite-based luminescent material provided by the application can generate light of different colors, can realize multiple anti-counterfeiting, and has the advantages of simple preparation process, low cost and being conducive to industrialized mass production.

Description

Technical Field

[0001] This invention belongs to the field of detection materials technology, and relates to a double perovskite-based luminescent material, its preparation method, and its application in luminescent imaging or anti-counterfeiting. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Currently, dual perovskite-based luminescent materials show great potential in the field of anti-counterfeiting, but significant bottlenecks exist in their preparation and application. In terms of preparation, wet chemical methods are complex, environmentally unfriendly, and have low reproducibility; solid-state mechanical methods are time-consuming, prone to particle aggregation, and have a photoluminescence quantum yield (PLQY) of about 60%. Moreover, the raw material ratio, doping ratio, and reaction environment are strictly controlled, and deviations in parameters will reduce performance and increase costs.

[0004] In applications, the core problems are concentrated in two aspects: First, the luminescence and spectral tunability are insufficient, with PLQY typically only reaching 1%-1.6%, exhibiting a narrow emission spectrum, and being easily counterfeited due to its single emission mode, resulting in poor security. Second, the composite process with anti-counterfeiting substrates is immature, making it difficult to adapt for convenient identification, and mass production is challenging and costly. There is an urgent need to develop green, efficient, and cost-controllable preparation methods to address these application pain points. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a dual perovskite-based luminescent material and its preparation method, as well as its applications in luminescent imaging or anti-counterfeiting. The dual perovskite-based luminescent material provided by the present invention can produce different colors of light under excitation by light of different wavelengths, enabling multiple anti-counterfeiting measures. This solves the problem of immature anti-counterfeiting substrate composite processes and difficulty in adapting to convenient identification. The preparation method involves mixing and stirring the materials and then drying them. The preparation process is simple, low-cost, and conducive to large-scale industrial production.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] Firstly, a dual perovskite-based luminescent material with the molecular formula Cs2NaCrCl6:Tm 3+ / Yb 3+ Among them, Tm 3+ The molar doping concentration of Yb is 0.5~5%. 3+ The molar doping concentration is 2%~80%.

[0008] The above-mentioned luminescent composite nanomaterial Cs2NaCrCl6:Tm of the present invention 3+ / Yb 3+ It emits red and blue light at an excitation wavelength of 980nm.

[0009] The above-mentioned luminescent composite nanomaterial Cs2NaCrCl6:Tm of the present invention 3+ / Yb 3+ It emits violet light at an excitation wavelength of 241 nm.

[0010] In a second aspect, a method for preparing the double perovskite-based luminescent material described in the first aspect of the present invention involves dissolving cesium chloride, sodium chloride, chromium chloride, thulium chloride, and ytterbium chloride in water according to a stoichiometric ratio, mixing them evenly, and carrying out a solution synthesis reaction, followed by evaporation and drying to remove the solvent, thereby obtaining the material.

[0011] Thirdly, the application of the dual perovskite-based luminescent material described in the first aspect of the present invention in luminescent imaging or anti-counterfeiting.

[0012] The beneficial effects of this invention are as follows:

[0013] (1) The present invention provides a Cs2NaCrCl6:Tm-based 3+ / Yb 3+ The dual perovskite-based luminescent material emits red and blue light at an excitation wavelength of 980nm and violet light at an excitation wavelength of 241nm, enabling multiple anti-counterfeiting measures.

[0014] (2) The preparation process of the double perovskite-based luminescent material provided by the present invention is simple and low in cost, which is conducive to realizing large-scale industrial production.

[0015] (3) The dual perovskite-based luminescent material provided by the present invention can be used not only for luminescent imaging, but also for anti-counterfeiting and other fields, with a wide range of applications. Attached Figure Description

[0016] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0017] Figure 1 This refers to the Cs2NaCrCl6:2%Tm prepared in Example 3 of this invention. 3+ / 10%Yb 3+ Scanning electron microscope image of nanoparticles;

[0018] Figure 2 This refers to the Cs2NaCrCl6:2%Tm prepared in Example 3 of this invention. 3+ / 10%Yb 3+ X-ray diffraction pattern;

[0019] Figure 3 The Cs2NaCrCl6:x%Tm prepared in Examples 1-4 of this invention 3+ / 10%Yb3+ Under 980nm excitation, Tm 3+ The changing emission spectrum;

[0020] Figure 4 The Cs2NaCrCl6:x%Tm prepared in Examples 1-4 of this invention 3+ / 10%Yb 3+ Under 241nm excitation, Tm 3+ The changing emission spectrum;

[0021] Figure 5 The Cs2NaCrCl6:2%Tm prepared in Examples 5-13 of this invention 3+ / x%Yb 3+ Under 980nm excitation, Yb 3+ The changing emission spectrum;

[0022] Figure 6 The Cs2NaCrCl6:2%Tm prepared in Examples 5-13 of this invention 3+ / x%Yb 3+ Under 241nm excitation, Yb 3+ The changing emission spectrum;

[0023] Figure 7 The Cs2NaCrCl6:x%Tm prepared in Examples 5-13 of this invention 3+ / 10%Yb 3+ Under 980 nm excitation, the luminescence intensity at 487 nm varies with Tm. 3+ Concentration change graph;

[0024] Figure 8 The Cs2NaCrCl6:x%Tm prepared in Examples 5-13 of this invention 3+ / 10%Yb 3+ Under 241 nm excitation, the luminescence intensity at 411 nm varies with Tm. 3+ Concentration change graph;

[0025] Figure 9 The Cs2NaCrCl6:2%Tm prepared in Examples 5-13 of this invention 3+ / x%Yb 3+ Under 980 nm excitation, the luminescence intensity at 450 nm varies with Yb 3+ Concentration change graph;

[0026] Figure 10 The Cs2NaCrCl6:2%Tm prepared in Examples 5-13 of this invention 3+ / x%Yb 3+ Under 241 nm excitation, the luminescence intensity at 394 nm varies with Yb3+ Concentration change graph;

[0027] Figure 11 This is the emission spectrum of carbon dots (CDs) prepared in Example 14 of the present invention;

[0028] Figure 12 This is an application example of the present invention using Cs2NaCrCl6:2%Tm prepared in Example 12. 3+ / 60%Yb 3+ Anti-counterfeiting images excited at 365nm, 241nm, and 980nm. Detailed Implementation

[0029] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0030] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0031] Given that existing luminescent materials suffer from problems such as complex preparation processes, high costs, difficulty in signal identification, and easy counterfeiting of anti-counterfeiting technologies, this invention proposes a dual perovskite-based luminescent material, its preparation method, and its application in luminescent imaging or anti-counterfeiting.

[0032] A typical embodiment of the present invention provides a dual perovskite-based luminescent material with the molecular formula Cs2NaCrCl6:Tm 3+ / Yb 3+ Among them, Tm 3+ The molar doping concentration of Yb is 0.5~5%. 3+ The molar doping concentration is 2%~80%.

[0033] In some embodiments, Tm 3+ The molar doping concentration is 1.8–2.2%. Studies have shown that the luminescence intensity is higher under these conditions.

[0034] In some embodiments, Yb 3+ The molar doping concentration is 55%~65%. Studies have shown that the luminescence intensity is higher under these conditions.

[0035] In some embodiments, the dual perovskite-based luminescent material has a sheet-like nanoparticle structure.

[0036] In some embodiments, red and blue light are emitted under an excitation wavelength of 980 nm, and violet light is emitted under an excitation wavelength of 241 nm.

[0037] Another embodiment of the present invention provides a method for preparing the above-mentioned double perovskite-based luminescent material, wherein cesium chloride, sodium chloride, chromium chloride, thulium chloride and ytterbium chloride are dissolved in water in stoichiometric ratio, mixed evenly and subjected to solution synthesis reaction, and the solvent is evaporated to remove the material.

[0038] In some embodiments, the concentration of cesium chloride in the reaction system is 0.5~1M. In this invention, the unit M refers to mol / L.

[0039] In some embodiments, the solution synthesis reaction time is 25-35 min.

[0040] The present invention does not impose any special restrictions on the purification method of the double perovskite-based luminescent material. Common purification methods in the field can be used. The purification method of the present invention is to dry the liquid after the solution synthesis reaction to obtain the luminescent material.

[0041] A third embodiment of the present invention provides an application of the above-mentioned double perovskite-based luminescent material in luminescent imaging or anti-counterfeiting.

[0042] The dual perovskite-based luminescent material provided by this invention can provide multiple anti-counterfeiting measures. It can generate a emission spectrum under specific wavelength laser excitation, emitting red and blue light under 980nm excitation and violet light under 241nm excitation, and the material also has better anti-counterfeiting capabilities.

[0043] In some embodiments, when used for anti-counterfeiting, carbon quantum dots and the dual perovskite-based luminescent material are used to form an anti-counterfeiting pattern.

[0044] Specifically, the distribution pattern of the dual perovskite-based luminescent material in the anti-counterfeiting pattern is used as the encryption key.

[0045] Specifically, the carbon quantum dots are obtained from citric acid via a hydrothermal reaction. More specifically, the hydrothermal reaction is carried out at a temperature of 178–182 °C for a time of 5.5–6.5 h.

[0046] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0047] In the following examples, Examples 1-4 provide Cs2NaCrCl6:x%Tm 3+ / 10%Yb 3+Its preparation method; Examples 5-13 provide Cs2NaCrCl6:2%Tm 3+ / x%Yb 3+ And its preparation method.

[0048] Example 1

[0049] This embodiment provides Cs2NaCrCl6:0.5%Tm 3+ / 10%Yb 3+ The preparation method includes the following steps:

[0050] (1) Add 0.3367g of cesium chloride, 0.0584g of sodium chloride, and 0.1mL of ytterbium chloride solution (1 M) to each test tube. Then add thulium chloride with a doping molar concentration of 0.5%. Weigh out chromium chloride with a doping molar concentration of 89.5% and add it to the test tube. Add 2mL of ultrapure water and a magnetic stir bar, and place it on a magnetic stirrer to stir evenly until the solution is clear. The time is about 0.5h.

[0051] (2) Place the above clear solution in a drying oven and keep it at 60°C for 5 days to obtain a purple solid, which is then ground into powder.

[0052] Example 2

[0053] This embodiment provides Cs2NaCrCl6:1%Tm 3+ / 10%Yb 3+ The preparation method includes the following steps:

[0054] (1) Add 0.3367g of cesium chloride, 0.0584g of sodium chloride, and 0.1mL of ytterbium chloride solution (1 M) to each test tube. Then add thulium chloride with a doping molar concentration of 1%. Weigh out chromium chloride with a doping molar concentration of 89% and add it to the test tube. Add 2mL of ultrapure water and a magnetic stir bar, and place it on a magnetic stirrer to stir evenly until the solution is clear. The time is about 0.5h.

[0055] (2) Place the above clear solution in a drying oven and keep it at 60°C for 5 days to obtain a purple solid, which is then ground into powder.

[0056] Example 3

[0057] This embodiment provides Cs2NaCrCl6:2%Tm 3+ / 10%Yb 3+ The preparation method includes the following steps:

[0058] (1) Add 0.3367g of cesium chloride, 0.0584g of sodium chloride, and 0.1mL of ytterbium chloride solution (1 M) to each test tube. Then add thulium chloride with a doping molar concentration of 2%. Weigh out chromium chloride with a doping molar concentration of 88% and add it to the test tube. Add 2mL of ultrapure water and a magnetic stir bar, and place it on a magnetic stirrer to stir evenly until the solution is clear. The time is about 0.5h.

[0059] (2) Place the above clear solution in a drying oven and keep it at 60°C for 5 days to obtain a purple solid, which is then ground into powder.

[0060] Example 4

[0061] This embodiment provides Cs2NaCrCl6:5%Tm 3+ / 10%Yb 3+ The preparation method includes the following steps:

[0062] (1) Add 0.3367g of cesium chloride, 0.0584g of sodium chloride, and 0.1mL of ytterbium chloride solution (1 M) to each test tube. Then add thulium chloride with a doping molar concentration of 5%. Weigh out chromium chloride with a doping concentration of 85% and add it to the test tube. Add 2mL of ultrapure water and a magnetic stir bar, and place it on a magnetic stirrer to stir evenly until the solution is clear. The time is about 0.5h.

[0063] (2) Place the above clear solution in a drying oven and keep it at 60°C for 5 days to obtain a purple solid, which is then ground into powder.

[0064] The Cs2NaCrCl6:x%Tm prepared in Examples 1-4 were analyzed by scanning electron microscopy. 3+ / 10%Yb 3+ The test results showed that the Cs2NaCrCl6 prepared in Examples 1-4 had a Tm content of x%. 3+ / 10%Yb 3+ The prepared nanoparticles are in sheet form, among which, the Cs2NaCrCl6:2%Tm prepared in Example 3 3+ / 10%Yb 3+ like Figure 1 As shown.

[0065] Figure 2 It is the Cs2NaCrCl6:2%Tm prepared in Example 3. 3+ / 10%Yb 3+ X-ray diffraction (XRD) spectra are used to characterize crystal structure. By comparing the experimental spectra (black curves) with the standard PDF cards (red vertical lines), the crystal phase and crystallinity of the sample can be determined. The results show that the sample has a high degree of matching with the standard crystal and good crystallization.

[0066] The powders prepared in Examples 1-4 were used to determine the Cs2NaCrCl6:x%Tm. 3+ / 10%Yb 3+ With Tm 3+ The changing emission spectrum, such as Figure 3 As shown, the emission peak is at 487 nm, and the excitation source used is 980 nm. Then, the emission intensity at 487 nm as a function of Tm is plotted. 3+ Concentration change graph, such as Figure 7 As shown. It can be observed that when Tm 3+ The concentration of 2% is the highest, with Figure 3 It can be matched.

[0067] The powders prepared in Examples 1-4 were used to determine the Cs2NaCrCl6:x%Tm. 3+ / 10%Yb 3+ With Tm 3+ The changing emission spectrum, such as Figure 4 As shown, the emission peak is at 411 nm, and the excitation source used is 241 nm. Then, the emission intensity at 411 nm as a function of Tm is plotted. 3+ Concentration change graph, such as Figure 8 As shown. It can be observed that when Tm 3+ The concentration of 2% is the highest, with Figure 4 It can be matched.

[0068] Example 5

[0069] This embodiment provides Cs2NaCrCl6:2%Tm 3+ / 2%Yb 3+ The preparation method includes the following steps:

[0070] (3) Add 0.3367g of cesium chloride, 0.0584g of sodium chloride, and 0.2mL of thulium chloride solution (0.1M) to each test tube. Then add ytterbium chloride with a doping molar concentration of 2%. Weigh out chromium chloride with a doping molar concentration of 96% and add it to the test tube. Add 2mL of ultrapure water and a magnetic stir bar, and place it on a magnetic stirrer to stir evenly until the solution is clear. The time is about 0.5h.

[0071] (2) Place the above clear solution in a drying oven and keep it at 60°C for 5 days to obtain a purple solid, which is then ground into powder.

[0072] Example 6

[0073] This embodiment provides Cs2NaCrCl6:2%Tm 3+ / 7%Yb 3+ The preparation method includes the following steps:

[0074] (3) Add 0.3367g of cesium chloride, 0.0584g of sodium chloride, and 0.2mL of thulium chloride solution (0.1M) to each test tube. Then add ytterbium chloride with a doping molar concentration of 7%. Weigh out chromium chloride with a doping molar concentration of 91% and add it to the test tube. Add 2mL of ultrapure water and a magnetic stir bar, and place it on a magnetic stirrer to stir evenly until the solution is clear. The time is about 0.5h.

[0075] (2) Place the above clear solution in a drying oven and keep it at 60°C for 5 days to obtain a purple solid, which is then ground into powder.

[0076] Example 7

[0077] This embodiment provides Cs2NaCrCl6:2%Tm 3+ / 10%Yb 3+ The preparation method includes the following steps:

[0078] (3) Add 0.3367g of cesium chloride, 0.0584g of sodium chloride, and 0.2mL of thulium chloride solution (0.1M) to each test tube. Then add ytterbium chloride with a doping molar concentration of 10%. Weigh out chromium chloride with a doping molar concentration of 88% and add it to the test tube. Add 2mL of ultrapure water and a magnetic stir bar, and place it on a magnetic stirrer to stir evenly until the solution is clear. The time is about 0.5h.

[0079] (2) Place the above clear solution in a drying oven and keep it at 60°C for 5 days to obtain a purple solid, which is then ground into powder.

[0080] Example 8

[0081] This embodiment provides Cs2NaCrCl6:2%Tm 3+ / 15%Yb 3+ The preparation method includes the following steps:

[0082] (3) Add 0.3367g of cesium chloride, 0.0584g of sodium chloride, and 0.2mL of thulium chloride solution (0.1M) to each test tube. Then add ytterbium chloride with a doping molar concentration of 15%. Weigh out chromium chloride with a doping molar concentration of 83% and add it to the test tube. Add 2mL of ultrapure water and a magnetic stir bar, and place it on a magnetic stirrer to stir evenly until the solution is clear. The time is about 0.5h.

[0083] (2) Place the above clear solution in a drying oven and keep it at 60°C for 5 days to obtain a purple solid, which is then ground into powder.

[0084] Example 9

[0085] This embodiment provides Cs2NaCrCl6:2%Tm 3+ / 20%Yb 3+The preparation method includes the following steps:

[0086] (3) Add 0.3367g of cesium chloride, 0.0584g of sodium chloride, and 0.2mL of thulium chloride solution (0.1M) to each test tube. Then add ytterbium chloride with a doping molar concentration of 20%. Weigh out chromium chloride with a doping molar concentration of 78% and add it to the test tube. Add 2mL of ultrapure water and a magnetic stir bar, and place it on a magnetic stirrer to stir evenly until the solution is clear. The time is about 0.5h.

[0087] (2) Place the above clear solution in a drying oven and keep it at 60°C for 5 days to obtain a purple solid, which is then ground into powder.

[0088] Example 10

[0089] This embodiment provides Cs2NaCrCl6:2%Tm 3+ / 30%Yb 3+ The preparation method includes the following steps:

[0090] (3) Add 0.3367g of cesium chloride, 0.0584g of sodium chloride, and 0.2mL of thulium chloride solution (0.1M) to each test tube. Then add ytterbium chloride with a doping molar concentration of 30%. Weigh out chromium chloride with a doping molar concentration of 68% and add it to the test tube. Add 2mL of ultrapure water and a magnetic stir bar, and place it on a magnetic stirrer to stir evenly until the solution is clear. The time is about 0.5h.

[0091] (2) Place the above clear solution in a drying oven and keep it at 60°C for 5 days to obtain a purple solid, which is then ground into powder.

[0092] Example 11

[0093] This embodiment provides Cs2NaCrCl6:2%Tm 3+ / 40%Yb 3+ The preparation method includes the following steps:

[0094] (3) Add 0.3367g of cesium chloride, 0.0584g of sodium chloride, and 0.2mL of thulium chloride solution (0.1M) to each test tube. Then add ytterbium chloride with a doping molar concentration of 40%. Weigh out chromium chloride with a doping molar concentration of 58% and add it to the test tube. Add 2mL of ultrapure water and a magnetic stir bar, and place it on a magnetic stirrer to stir evenly until the solution is clear. The time is about 0.5h.

[0095] (2) Place the above clear solution in a drying oven and keep it at 60°C for 5 days to obtain a purple solid, which is then ground into powder.

[0096] Example 12

[0097] This embodiment provides Cs2NaCrCl6:2%Tm 3+ / 60%Yb 3+ The preparation method includes the following steps:

[0098] (3) Add 0.3367g of cesium chloride, 0.0584g of sodium chloride, and 0.2mL of thulium chloride solution (0.1M) to each test tube. Then add ytterbium chloride with a doping molar concentration of 60%. Weigh out chromium chloride with a doping molar concentration of 38% and add it to the test tube. Add 2mL of ultrapure water and a magnetic stir bar, and place it on a magnetic stirrer to stir evenly until the solution is clear. The time is about 0.5h.

[0099] (2) Place the above clear solution in a drying oven and keep it at 60°C for 5 days to obtain a purple solid, which is then ground into powder.

[0100] Example 13

[0101] This embodiment provides Cs2NaCrCl6:2%Tm 3+ / 80%Yb 3+ The preparation method includes the following steps:

[0102] (3) Add 0.3367g of cesium chloride, 0.0584g of sodium chloride, and 0.2mL of thulium chloride solution (0.1M) to each test tube. Then add ytterbium chloride with a doping molar concentration of 80%. Weigh out chromium chloride with a doping molar concentration of 18% and add it to the test tube. Add 2mL of ultrapure water and a magnetic stir bar, and place it on a magnetic stirrer to stir evenly until the solution is clear. The time is about 0.5h.

[0103] (2) Place the above clear solution in a drying oven and keep it at 60°C for 5 days to obtain a purple solid, which is then ground into powder.

[0104] Take a portion of the powder to determine the Tm of Cs2NaCrCl6:2% 3+ / x%Yb 3+ With Yb 3+ The changing emission spectrum, such as Figure 5 As shown, the emission peak is at 450 nm, and the excitation source used is 980 nm. Then, the emission intensity at 450 nm as a function of Yb is plotted. 3+ Concentration change graph, such as Figure 9 As shown. It can be observed that when Yb 3+ Its strength is highest at a concentration of 60%, and... Figure 5 It can be matched.

[0105] Take a portion of the powder to determine the Tm of Cs2NaCrCl6:2% 3+ / x%Yb 3+ With Yb 3+ The changing emission spectrum, such as Figure 6 As shown, the emission peak is at 394 nm, and the excitation source used is 241 nm. Then, the emission intensity at 394 nm as a function of Yb is plotted. 3+ Concentration change graph, such as Figure 10 As shown. It can be observed that when Yb 3+ Its strength is highest at a concentration of 60%, and... Figure 6 It can be matched.

[0106] Example 14

[0107] This embodiment provides the preparation of carbon dots (CDs), including the following steps:

[0108] (1) Weigh 19.212g of citric acid and add it to a beaker. Add 20mL of water and stir until homogeneous to obtain a citric acid (0.1mol) aqueous solution. Then add 11.98mL of ethanolamine (0.2mol) aqueous solution to the citric acid aqueous solution and stir vigorously until the solution is clear.

[0109] (2) Seal the above-mentioned clear solution in a reaction vessel and heat it to 180°C. o Keep it at 6°C for 6 hours, then allow it to cool naturally to room temperature to obtain a reddish-brown liquid.

[0110] (3) Rotary evaporation: The reddish-brown liquid obtained in step (2) is rotary evaporated, and then dialyzed for 3 days with a dialysis bag to remove unreacted ethanolamine precursor and small molecule products. The liquid is then freeze-dried to obtain carbon dots.

[0111] Determine the emission spectrum of carbon dots, such as Figure 11 As shown, when the wavelength of the excitation source used is 365nm and the power is 4W, its emission peak is near 439nm.

[0112] Application examples

[0113] The materials from Examples 1-13 were used in anti-counterfeiting experiments, and the specific steps are as follows:

[0114] (1) Prepare two 0.3g portions of polyvinyl alcohol, add 100ml of water to each to make polyvinyl alcohol liquid colloid, and add 0.1g of luminescent composite nanomaterial powder Cs2NaCrCl6:Tm to one portion of the polyvinyl alcohol liquid colloid. 3+ / Yb 3+ Stir well, then add 1 ml of carbon dot aqueous solution (50 μg / ml) to another portion of polyvinyl alcohol liquid colloid and stir well.

[0115] (2) Prepare suitable cardstock, cover the seahorse's cutout pattern, coat it with the ink obtained above, and dry it to obtain the corresponding pattern. When coating, select the seahorse's body area to coat with carbon dots, and coat the eye area with Cs2NaCrCl6:Tm. 3+ / Yb 3+Nanoparticles were used, and the distribution pattern was used as the encryption key. During verification, different wavelengths (241 nm, 980 nm) were used for excitation, and the distribution pattern was read and compared with the preset key. Specifically, the Cs₂NaCrCl₆:2%Tm nanoparticles prepared in Example 12... 3+ / 60%Yb 3+ The excitation sources used were 241 nm and 980 nm. The excitation source used for the carbon dots prepared in Example 14 was 365 nm. The results are as follows: Figure 12 As shown.

[0116] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dual perovskite-based luminescent material, characterized in that, Its molecular formula is Cs2NaCrCl6:Tm 3+ / Yb 3+ Among them, Tm 3+ The molar doping concentration of Yb is 1.8~2.2%. 3+ The molar doping concentration is 55%~65%; It emits red and blue light under an excitation wavelength of 980 nm, and violet light under an excitation wavelength of 241 nm.

2. The dual perovskite-based luminescent material as described in claim 1, characterized in that, The dual perovskite-based luminescent material has a sheet-like nanoparticle structure.

3. A method for preparing the dual perovskite-based luminescent material according to any one of claims 1 to 2, characterized in that, Cesium chloride, sodium chloride, chromium chloride, thulium chloride, and ytterbium chloride are dissolved in water according to stoichiometric ratios, mixed thoroughly, and subjected to a solution synthesis reaction. The solvent is then evaporated to remove the solvent, thus obtaining the final product.

4. The preparation method according to claim 3, characterized in that, In the reaction system, the concentration of cesium chloride is 0.5~1M.

5. The preparation method according to claim 3, characterized in that, The reaction time for solution synthesis is 25-35 minutes.

6. The application of the dual perovskite-based luminescent material according to any one of claims 1 to 2 in luminescent imaging or anti-counterfeiting.

7. The application as described in claim 6, characterized in that, When used for anti-counterfeiting purposes, carbon quantum dots and the aforementioned double perovskite-based luminescent material are used to form an anti-counterfeiting pattern.

8. The application as described in claim 7, characterized in that, The distribution pattern of the dual perovskite-based luminescent material in the anti-counterfeiting pattern is used as the encryption key.

9. The application as described in claim 7, characterized in that, The carbon quantum dots are obtained from citric acid via a hydrothermal reaction.

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