Preparation method of single crystal with high-efficiency near-infrared light emission

Abstract

The application discloses a preparation method of a single crystal with high-efficiency near-infrared light emission, and is characterized in that the method comprises the following steps: weighing CsX, NaX, YbX3 and CrX3 according to the proportion of CsX:NaX:YbX3:CrX3=(45-55mol%):(20-30mol%):(20-25mol%):(5-10mol%) in mole percentage; placing the weighed NaX, YbX3 and CrX3 in a 20ml glass bottle, adding a proper amount of concentrated hydrochloric acid under a certain temperature condition to dissolve the raw materials, then adding CsX to generate flocculent precipitate, heating and stirring to fully react, then transferring the obtained solution to a reaction kettle container, sealing in an autoclave, heating and keeping warm by using a heating and keeping warm device, and controlling to cool to room temperature to obtain the single crystal. The single crystal with high-efficiency near-infrared light emission has good crystallinity and good stability, and the near-infrared light source exhibits excellent application effect in the field of night vision illumination and the like.

Description

Technical Field

[0001] This invention belongs to the field of near-infrared fluorescent materials technology, specifically relating to a method for preparing a single crystal with high-efficiency near-infrared luminescence. Background Technology

[0002] Near-infrared (NIR) light sources, due to their low thermal effect and large penetration depth, show great application potential in many fields such as food safety, night vision security monitoring, medical treatment, and bioimaging. This has made the search for efficient NIR phosphor materials as next-generation NIR fluorescent light-emitting diodes (NIR pc-LEDs) a research hotspot. However, the NIR luminescence efficiency in metal halide perovskites is still very low. Therefore, finding new host matrices and using doping strategies to modulate the optical properties of rare earth elements to achieve efficient NIR luminescence is of great significance. Recently, rare earth-based double perovskites have attracted attention due to their unique optical properties. Currently, reports on the characteristic narrow-band 4f-4f NIR luminescence of rare earth ions in rare earth-based double perovskites are very scarce, and their NIR luminescence efficiency remains low. Therefore, finding suitable synthesis processes and metal ion doping strategies to obtain efficient rare earth-based double perovskite NIR fluorescent materials is of great importance.

[0003] Therefore, this paper proposes a method for preparing single crystals with high efficiency near-infrared luminescence. Summary of the Invention

[0004] The purpose of this invention is to provide a simple, non-toxic, and stable single crystal with high efficiency near-infrared luminescence and its preparation method. This single crystal can expand the application range of rare earth ions in the field of near-infrared luminescence of double perovskites, and provide a new idea and strategy for the design and preparation of high efficiency rare earth ion near-infrared luminescent materials realized by the rare earth-based double perovskite doping metal ion strategy.

[0005] To achieve the above-mentioned technical effects, the present invention is implemented through the following technical solution: a method for preparing a single crystal with high efficiency near-infrared luminescence, characterized by comprising the following steps:

[0006] S1. Weigh CsX, NaX, YbX3, and CrX3 according to the following molar percentages: CsX:NaX:YbX3:CrX3 = (45-55 mol%):(20-30 mol%):(20-25 mol%):(5-10 mol%); prepare a glass bottle, a magnetic stirrer with a magnetic stir bar, a heating and insulation device, an organic solvent, a heat treatment reaction vessel, and concentrated hydrochloric acid or concentrated nitric acid; wherein X is one or more of the elements Cl, Br, I, and F;

[0007] S2. First, place the raw materials NaX, YbX3, and CrX3 in a glass bottle, add concentrated hydrochloric acid or concentrated nitric acid, and stir on a magnetic stirrer at 70℃~100℃ for 2~5 hours until the raw materials are completely dissolved and transparent.

[0008] S3. Then add the CsX weighed in proportion. At this time, the reaction will produce flocculent products that sink to the bottom. Continue stirring for 1 to 3 hours and let stand for 1 to 2 hours to ensure the reaction is complete.

[0009] S4. Then, the solution is transferred to the lining of the heat treatment reaction vessel, and kept at 150℃~200℃ for 12~15 hours. Then, the temperature is controlled to drop to room temperature at a rate of 2℃~5℃ per hour. The product is then washed 1~3 times with organic solvent. The obtained product is dried in a heating and holding device at 60~80℃ for 8~10 hours to obtain a highly efficient near-infrared luminescent single crystal.

[0010] Furthermore, in S1, the purity of the CsX, NaX, YbX3, and CrX3 raw materials is 99.99%.

[0011] Furthermore, in S1, the organic solvent is ethanol or isopropanol.

[0012] Furthermore, in S2, the mass ratio of the CsX, NaX, YbX3, and CrX3 raw materials to concentrated hydrochloric acid is 1g:10-20ml.

[0013] Furthermore, in S2, the volume of the glass bottle is 20-40 ml.

[0014] Furthermore, in S4, the lining volume of the heat treatment reaction vessel is 25ml to 50ml.

[0015] Furthermore, in S4, the heating and heat preservation device is an electric heating drying oven or a muffle furnace.

[0016] Furthermore, in S4, the atmosphere in the heating and heat preservation device is one or more combinations of air, nitrogen, and argon.

[0017] The beneficial effects of this invention are:

[0018] The single crystal of this invention exhibits high-efficiency near-infrared luminescence, which is non-toxic compared to traditional lead-based halide perovskites and possesses excellent crystallinity and stability against light, heat, and humidity. Furthermore, research on achieving 4f-4f narrowband near-infrared luminescence of rare-earth ions in a lead-free rare-earth-based double perovskite matrix is ​​currently very limited, and the near-infrared luminescence efficiency of rare-earth ions can be significantly improved through metal ion doping strategies. This fluorescent material has broad application prospects in many fields such as night vision lighting and biomedical imaging. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A photograph of a single crystal with high efficiency near-infrared emission, as an embodiment of the present invention;

[0021] Figure 2 This is an X-ray diffraction pattern of a single crystal with high efficiency near-infrared luminescence according to an embodiment of the present invention;

[0022] Figure 3 The photoluminescence (PL) pattern of a single-crystal near-infrared fluorescent material with high efficiency near-infrared emission, as described in this embodiment of the invention, is shown at room temperature using a 365nm xenon lamp as the excitation source.

[0023] Figure 4 This is a bar chart showing the change in luminescence intensity of a single crystal with high near-infrared luminescence efficiency before and after metal ion modulation, according to an embodiment of the present invention.

[0024] Figure 5 This is a photograph of a night vision illumination device using a single crystal with high efficiency near-infrared emission as a fluorescent conversion type light-emitting diode, as an embodiment of the present invention. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1

[0027] A single crystal with high efficiency near-infrared luminescence and its preparation method are disclosed. The following proportions are used: 50 mol% CsCl, 25 mol% NaCl, 20 mol% YbCl, and 35 mol% CrCl. A glass bottle, a magnetic stirrer with a magnetic stir bar, a heating and heat preservation device, an organic solvent, a heat treatment reaction vessel, and concentrated hydrochloric acid or concentrated nitric acid are prepared.

[0028] First, place the raw material in a 20ml glass bottle, add concentrated hydrochloric acid, and stir on a magnetic stirrer at 80℃ for 5 hours until the raw material is completely dissolved and transparent.

[0029] Then add the CsCl weighed in proportion. At this time, the reaction produces flocculent products that sink to the bottom. Continue stirring for 3 hours and let stand for 2 hours to ensure the reaction is complete.

[0030] The solution was then transferred to the lining of a 25 ml heat treatment reaction vessel and kept at 200 °C for 12 hours. The temperature was then controlled to drop to room temperature at a rate of 3 °C per hour. The product was then washed three times with ethanol and dried at 70 °C for 10 hours to obtain a highly efficient near-infrared luminescent single crystal.

[0031] Depend on Figure 1 The photographs of the product show that the synthesized product is a single crystal, and it is a relatively large transparent single crystal.

[0032] The X-ray diffraction pattern of this highly efficient near-infrared luminescent single crystal was obtained by X-ray diffraction (XRD) at Rigaku Smart Lab SE in Japan. The results are shown in [Figure number missing]. Figure 2 Rare earth-based double perovskites can maintain a good pure phase structure both before and after metal ion doping.

[0033] Furthermore, we tested the photoluminescence (PL) spectra of single crystals of rare-earth-based double perovskites before and after metal ion doping. We selected a xenon lamp source of 365 nm, and the results are shown in [Figure number missing]. Figure 3 As can be seen from the figure, before the metal ions are doped, the single crystal of rare earth-based double perovskite can exhibit narrow-band 4f-4f characteristic near-infrared emission of rare earth ions. After the introduction of metal ions, the intensity of the near-infrared emission of rare earth ions is greatly enhanced. Figure 4 The bar chart shows the near-infrared luminescence intensity before and after metal ion doping. It can be seen that the luminescence intensity is increased by 17 times compared with the single crystal of rare earth-based double perovskite after the introduction of metal ions.

[0034] To demonstrate its application in the lighting display field, the fluorescent material was encapsulated with a commercial 365nm ultraviolet LED chip (using epoxy resin AB glue during encapsulation). To further showcase the application prospects of this near-infrared fluorescent conversion LED device in the field of night vision lighting, such as... Figure 5 The results show that screws can be clearly captured by near-infrared cameras in dark environments, which makes them a potential application source for night vision illumination.

Claims

1. A method for preparing a single crystal with high-efficiency near-infrared luminescence, characterized in that, Includes the following steps: S1. Weigh CsX, NaX, YbX3, and CrX3 according to the following molar percentages: CsX:NaX:YbX3:CrX3 = (45-55 mol%):(20-30 mol%):(20-25 mol%):(5-10 mol%); prepare a glass bottle, a magnetic stirrer with a magnetic stir bar, a heating and insulation device, an organic solvent, a heat treatment reaction vessel, and concentrated hydrochloric acid or concentrated nitric acid; wherein X is one or more of the elements Cl, Br, I, and F; S2. First, place the raw materials NaX, YbX3, and CrX3 in a glass bottle, add concentrated hydrochloric acid or concentrated nitric acid, and stir on a magnetic stirrer at 70℃~100℃ for 2~5 hours until the raw materials are completely dissolved and transparent. S3. Then add the CsX weighed in proportion. At this time, the reaction will produce flocculent products that sink to the bottom. Continue stirring for 1 to 3 hours and let stand for 1 to 2 hours to ensure the reaction is complete. S4. Then, the solution is transferred to the lining of the heat treatment reaction vessel, and kept at 150℃~200℃ for 12~15 hours. Then, the temperature is controlled to drop to room temperature at a rate of 2℃~5℃ per hour. The product is then washed 1~3 times with organic solvent. The obtained product is dried in a heating and holding device at 60~80℃ for 8~10 hours to obtain a highly efficient near-infrared luminescent single crystal.

2. The method for preparing a single crystal with high-efficiency near-infrared luminescence according to claim 1, characterized in that: In S1, the purity of the raw materials CsX, NaX, YbX3, and CrX3 is 99.99%.

3. The method for preparing a single crystal with high-efficiency near-infrared luminescence according to claim 1, characterized in that: In S1, the organic solvent is ethanol or isopropanol.

4. The method for preparing a single crystal with high-efficiency near-infrared luminescence according to claim 1, characterized in that: In S2, the mass ratio of the raw materials CsX, NaX, YbX3, and CrX3 to concentrated hydrochloric acid is 1g:10-20ml.

5. The method for preparing a single crystal with high-efficiency near-infrared luminescence according to claim 1, characterized in that: In S2, the volume of the glass bottle is 20-40 ml.

6. The method for preparing a single crystal with high-efficiency near-infrared luminescence according to claim 2, characterized in that: In S4, the lining volume of the heat treatment reaction vessel is 25ml to 50ml.

7. The method for preparing a single crystal with high efficiency near-infrared luminescence according to claim 1, characterized in that: In S4, the heating and heat preservation device is an electric heating drying oven or a muffle furnace.

8. The method for preparing a single crystal with high efficiency near-infrared luminescence according to claim 1, characterized in that: In S4, the atmosphere in the heating and heat preservation device is one or more combinations of air, nitrogen, and argon.

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