A rare earth-doped ABF3 perovskite nanomaterial with light-emitting properties, its preparation method and application

Abstract

The application discloses a rare earth doped ABF3 perovskite type nano luminescent material, a preparation method and application thereof, and a general formula of the luminescent material is ABF3:x mol%Ln n+ wherein A is selected from at least one of alkali metals Li, Na, K, Rb, Cs; B is selected from at least one of alkaline earth metals or transition group metals Mg, Ca, Sr, Ba, Mn, Zn, Cd, Co, Ni, Cu; F represents fluorine element; Ln represents lanthanide rare earth element; x mol% represents a percentage of lanthanide rare earth ions in a total number of moles of alkaline earth metals or transition group metals and lanthanide rare earth elements, 0

Description

Technical Field

[0001] This invention belongs to the field of nanoluminescent materials technology, specifically relating to a rare earth-doped ABF3 perovskite nanoluminescent material, its preparation method, and its application. Background Technology

[0002] Perovskite nanocrystals, with the general formula ABF3 (where A is an alkali metal ion and B is a divalent metal cation), are ideal rare-earth doping matrix materials due to their high optical transparency, low phonon energy, good thermal stability, anisotropy, and wide bandgap. Currently, methods for preparing rare-earth-doped ABF3 perovskite nanocrystals mainly include aqueous / solvothermal and high-temperature coprecipitation methods. Among these, the aqueous / solvothermal method has a long reaction time, and the prepared nanocrystals are prone to agglomeration and uncontrollable particle size. Furthermore, when using this method, hydroxyl groups in the reaction system easily replace fluoride ions and enter the nanocrystal interior, forming hydroxyl defects and causing severe quenching of the nanocrystal's luminescence. The high-temperature coprecipitation method for preparing nanocrystals has a mild reaction and easily controllable reaction conditions, and can obtain monodisperse rare-earth-doped nanocrystals. However, previous researchers using this method to prepare ABF3 perovskite nanocrystals mainly used NH4F and AOH as fluorine and A sources, respectively. The use of AOH increases the hydroxyl content in the system. A large number of hydroxyl groups participate in the nucleation and growth process of nanocrystals, leading to the formation of numerous hydroxyl defects on and inside the nanocrystals, thus affecting their luminescence efficiency. Furthermore, nanocrystals prepared using NH4F as the fluorine source have smaller particle sizes, making it difficult to control their size. Limited by the types of reaction precursors and preparation methods, the preparation of rare-earth-doped ABF3 perovskite nanocrystals with high luminescence efficiency remains a major challenge.

[0003] Rare-earth-doped photon avalanche upconversion nanocrystals hold great promise for applications in cutting-edge technologies such as super-resolution bioimaging, microlasers, single-molecule tracking, and quantum optics. However, due to fluorescence quenching effects caused by surface and internal hydroxyl defects in nanocrystals, achieving high-order nonlinear photon avalanche upconversion at room temperature remains a significant challenge in the field of rare-earth luminescence. The heterovalent doping of rare-earth ions in ABF3 facilitates the formation of rare-earth ion clusters, promoting cross-relaxation processes between these ions and thus facilitating photon avalanche upconversion. Therefore, developing novel synthesis techniques to achieve the controlled synthesis of highly efficient rare-earth-doped ABF3 perovskite-type luminescent nanomaterials is crucial for realizing high-order nonlinear photon avalanche upconversion of rare-earth ions and their applications in super-resolution imaging and other fields. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a rare-earth-doped ABF3 perovskite-type nanoluminescent material, wherein the general formula of the luminescent material is ABF3:x mol%Ln n+, wherein, A is selected from at least one of alkali metals Li, Na, K, Rb, Cs; B is selected from at least one of alkaline earth metals or transition group metals Mg, Ca, Sr, Ba, Mn, Zn, Cd, Co, Ni, Cu; F represents fluorine element, and Ln represents lanthanide rare earth element; x mol% represents the percentage of lanthanide rare earth ions in the total molar amount of alkaline earth metals or transition group metals and lanthanide rare earth elements, 0 < x ≤ 80; n is 2 or 3.

[0005] According to an embodiment of the present invention, the A is K and / or Na.

[0006] According to an embodiment of the present invention, the B is Mg and / or Zn.

[0007] According to an embodiment of the present invention, the Ln n+ is selected from 3+ Ho 3+ Er 3+ Tm 3+ Tb 3+ Eu 2+ Ce 3+ Sm 3+ Sm 2+ Dy 3+ Nd 3+ Pr 3+ Gd 3+ Sc 3+ Lu 3+ Yb 3+ Yb 2+ Y 3+ La 3+ and at least one of them, preferably Yb 3+ Er 3+ Ho 3 + Tm 3+ and at least one of them.

[0008] According to an embodiment of the present invention, 0.0001% ≤ x ≤ 80, preferably 0.01 ≤ x ≤ 40, more preferably 1 ≤ x ≤ 40, still more preferably 1 ≤ x ≤ 30. Exemplarily, x is 0.01, 1, 2, 3, 5, 10, 15, 20, 25, 30, 35, 40.

[0009] According to an embodiment of the present invention, the luminescent material is KMgF3:20mol%Yb 3+ ,2mol%Er 3+ 、KMgF3:20mol%Yb 3+ ,1mol%Ho 3+ 、KMgF3:1mol%Yb 3+KMgF3:5mol%Yb 3+ KMgF3:10mol%Yb 3+ KMgF3:20mol%Yb 3+ KMgF3:30mol%Yb 3+ Or KMgF3:1mol%Tm 3+ KMgF3: 3mol%Tm 3+ KMgF3: 5mol%Tm 3+ Or NaMgF3:5mol%Yb 3+ Or KZnF3:2mol%Yb 3+ .

[0010] According to an embodiment of the present invention, the particle size of the luminescent material is 5-200nm, preferably 10-50nm, and exemplary of 10nm, 12nm, 17nm, 20nm, 21nm, 25nm, 30nm, 35nm, 40nm, 45nm, and 50nm.

[0011] According to an embodiment of the present invention, the luminescent material has a core-shell structure, wherein the central region is composed of rare earth elements, and the peripheral region is composed of elements A, B, and fluorine.

[0012] According to an embodiment of the present invention, the luminescent material is a cubic phase or an orthorhombic phase.

[0013] According to an embodiment of the present invention, the nanoluminescent material can achieve high-order nonlinear photon avalanche upconversion at room temperature.

[0014] This invention also provides a method for preparing the above-mentioned rare-earth-doped ABF3 perovskite-type luminescent nanomaterials, the method comprising:

[0015] B salt, Ln salt and hydrofluoric acid A were dissolved in an organic solvent and heated to react, thus obtaining the rare earth-doped ABF3 perovskite-type luminescent nanomaterial.

[0016] Among them, A, B, and Ln have the definitions described above.

[0017] According to an embodiment of the present invention, the hydrofluoric acid A is added in the form of a solution. The hydrofluoric acid A solution is prepared by dissolving hydrofluoric acid A in water or an alcohol solvent, such as ethanol or methanol. The concentration of the hydrofluoric acid A solution is 1-5 mol / L, preferably 1.5-4 mol / L.

[0018] Preferably, the method includes the following steps:

[0019] (1) Dissolve salt B and salt Ln in an organic solvent to form a salt solution;

[0020] (2) Add hydrofluoric acid A solution to the salt solution obtained in step (1); heat the reaction to prepare the rare earth-doped ABF3 perovskite nanoluminescent material.

[0021] According to an embodiment of the present invention, the heating reaction time is 1-240 min, preferably 30-180 min. By using different reaction times, the present invention can obtain ABF3 perovskite-type luminescent nanomaterials with different sizes, morphologies, and luminescent properties. Within the time range of the present invention, if other conditions remain unchanged, the longer the reaction time, the larger the size of the resulting luminescent material, the better its luminescent performance, and the higher its luminescent efficiency.

[0022] According to an embodiment of the present invention, the heating reaction temperature is 100-400℃, preferably 200-330℃, and exemplary values ​​are 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 280℃, 290℃, 300℃, 310℃, 320℃, and 330℃. By using different reaction temperatures, the present invention can obtain ABF3 perovskite-type nanoluminescent materials with different sizes, morphologies, and luminescent properties. Within the temperature range of the present invention, if other conditions remain unchanged, the higher the reaction temperature, the larger the size of the luminescent material, the better its luminescent performance, and the higher the luminescent efficiency.

[0023] According to embodiments of the present invention, the B salt is selected from B-containing halides, acetates, nitrates, oxalates, acetylacetone salts, or their crystalline hydrates; preferably B-containing acetates or their crystalline hydrates. For example, it is selected from at least one of Mg(CH3COO)2, Ca(CH3COO)2, Sr(CH3COO)2 or Ba(CH3COO)2, Mn(CH3COO)2, Zn(CH3COO)2, Cd(CH3COO)2, Co(CH3COO)2, Cu(CH3COO)2 or Ni(CH3COO)2.

[0024] According to an embodiment of the present invention, the Ln salt is selected from at least one of Ln-containing halides, acetates, nitrates, oxalates, acetylacetone salts, or at least one of the crystalline hydrates of these salts. For example, it is selected from one or more of La(CH3COO)3, Ce(CH3COO)3, Pr(CH3COO)3, Nd(CH3COO)3, Sm(CH3COO)3, Eu(CH3COO)3, Gd(CH3COO)3, Tb(CH3COO)3, Dy(CH3COO)3, Ho(CH3COO)3, Er(CH3COO)3, Tm(CH3COO)3, Yb(CH3COO)3, Lu(CH3COO)3, Y(CH3COO)3, and Sc(CH3COO)3, preferably at least one of Yb(CH3COO)3·4H2O, Er(CH3COO)3·4H2O, Ho(CH3COO)3·4H2O, and Tm(CH3COO)3·4H2O.

[0025] According to an embodiment of the present invention, the organic solvent is selected from at least one of oleic acid, oleylamine, trioctylamine, and octadecene. Preferably, it is a mixture of oleic acid and octadecene.

[0026] According to an embodiment of the present invention, when the organic solvent is a mixed solvent, it is a mixture of oleic acid, oleylamine, and octadecene; the volume ratio of the oleic acid, oleylamine, and octadecene is (1-10):(0-10):(1-100), preferably (1-6):(0-6):(1-50), and even more preferably (1-2):(0-6):(2-6), for example 1:2:2, 2:3:5, 1:3:6, or 2:0:3.

[0027] According to the preparation method of the present invention, the reaction is carried out under the protection of an inert gas, such as nitrogen.

[0028] According to the preparation method of the present invention, the molar ratio of B salt to Ln salt is (1-x):x.

[0029] According to the preparation method of the present invention, the amount of hydrofluoric acid A is 1 to 5 times the sum of the molar numbers of B salt and Ln salt, preferably 1 to 3 times, and even more preferably 1.5 times.

[0030] According to an embodiment of the present invention, the method further includes post-processing steps: cooling, centrifuging, washing, drying, etc., of the prepared product.

[0031] According to an embodiment of the present invention, centrifugation refers to separating the obtained precipitate from the reaction system and obtaining a solid product by centrifugal separation; washing is to remove residual organic solvents on the surface of the solid product; the washing method can be filtration washing or centrifugal washing; the washing can be performed using at least one organic solvent such as acetone, acetonitrile, n-butanol, isopropanol, tert-butanol, diethyl ether, methyl ethyl ketone, octane, cyclohexane or toluene, preferably ethanol and / or cyclohexane. For example, the drying temperature is 30-100°C, preferably 50-80°C.

[0032] In this invention, the washed product is dried to obtain a rare earth-doped ABF3 perovskite-type nanoluminescent material solid powder.

[0033] According to an embodiment of the present invention, the method further includes: dispersing the rare earth-doped ABF3 perovskite nanoluminescent material in a nonpolar organic solvent to obtain a rare earth-doped ABF3 perovskite nanoluminescent material solution.

[0034] According to an embodiment of the present invention, the nonpolar organic solvent is selected from at least one of n-hexane, cyclohexane, chloroform, dichloromethane or toluene, preferably cyclohexane and / or toluene.

[0035] This invention also provides applications of the above-mentioned rare-earth-doped ABF3 perovskite nanoluminescent materials in fluorescence detection, bioimaging, super-resolution imaging, single-molecule tracing, optical anti-counterfeiting, and coding. Preferably, they are used in the fields of fluorescence detection and super-resolution imaging.

[0036] The beneficial effects of this invention are:

[0037] 1. The synthesis conditions of the preparation method of the present invention are easy to control. The synthesized luminescent material has a uniform morphology, is monodisperse, has an adjustable particle size, and spontaneously forms a core-shell structure. This can effectively reduce the fluorescence quenching effect on the surface of the luminescent material, effectively reduce the hydroxyl content in the reaction system, inhibit the generation of hydroxyl defects inside the luminescent material, and improve the luminescence efficiency of the luminescent material.

[0038] 2. The luminescent material of the present invention can be synthesized into the target product in a wide temperature range of 100 to 400°C. The luminescent material can be prepared in a controllable manner by changing the solvent ratio, reaction temperature and / or reaction time.

[0039] 3. The hydroxyl defects inside the luminescent material of the present invention are effectively suppressed, and the rare earth ions are heterovalently doped in it, which can promote the cross relaxation between rare earth ions and realize the high-order nonlinear photon avalanche upconversion of the luminescent material at room temperature. Attached Figure Description

[0040] Figure 1The KMgF3:20mol%Yb with different particle sizes (12, 17, 21, and 30 nm) in Example 1 3+ 2mol%Er 3+ X-ray powder diffraction pattern of nanocrystals.

[0041] Figure 2 The KMgF3:20mol%Yb with different particle sizes (12, 17, 21, and 30 nm) in Example 1 3+ 2mol%Er 3+ Transmission electron microscopy images of nanocrystals and their corresponding particle size statistics.

[0042] Figure 3 The 30nm KMgF3:20mol%Yb in Example 1 3+ 2mol%Er 3+ (a) Ring-shaped dark-field scanning electron microscope, (b) single-particle energy loss, (c) F, (d) Mg, (e) K, (f) Yb, (g) Er and (h) superimposed distribution of the above elements.

[0043] Figure 4 At room temperature and under 980 nm excitation, (a) different particle sizes of KMgF3:20 mol% Yb in Example 1 3+ 2mol%Er 3+ Nanocrystals, (b) KMgF3 with different particle sizes in Example 2: 20 mol% Yb 3+ 1mol%Ho 3+ Upconversion and downconversion emission spectra of nanocrystals, (c,d)Er 3+ of 4 F 9 / 2 Energy levels and 4 I 13 / 2 Fluorescence decay curves of energy levels, (e,f)Ho 3+ of 5 F4 and 5 Fluorescence decay curve of I6 level.

[0044] Figure 5 For different Yb in Example 3 3+ Doping concentration KMgF3:x mol% Yb 3+ X-ray powder diffraction patterns of nanocrystals (x = 0, 1, 5, 10, 20, 30).

[0045] Figure 6 In Example 3, (ac) represents different Yb. 3+ Doping concentration KMgF3:x mol% Yb 3+ The transmission electron microscope (df) images of the nanocrystals (x = 1, 10, 20) are the corresponding high-resolution transmission electron microscope images.

[0046] Figure 7 At room temperature, in Example 4, KMgF3: 5 mol% Tm 3+ Upconversion emission spectra under different excitation power densities when nanocrystals are excited at 1064 nm.

[0047] Figure 8 At room temperature, different Tm values ​​in Example 4 3+ Doping concentration KMgF3:x mol% Tm 3+ (x = 1, 3, 5), under 1064 nm excitation, (a) KMgF3:x mol%Tm 3+ In nanocrystals, Tm 3+ 802nm ( 3 H4→ 3 (a) Power dependence of upconversion luminescence at H6, the dashed line is the linear fit at the point where the slope of the nonlinear curve is the largest (excitation wavelength is 1064 nm); (b) KMgF3: xmol%Tm 3+ The nonlinear curve of the nanocrystals was linearly fitted to show the relationship between the slope and the excitation power density.

[0048] Figure 9 At room temperature, under 1064 nm excitation as in Example 4, KMgF3: 5 mol% Tm 3+ Time-resolved upconversion spectroscopy of nanocrystals.

[0049] Figure 10 At room temperature, in Example 5, NaMgF3:5 mol% Yb 3+ X-ray powder diffraction pattern of nanocrystals.

[0050] Figure 11 At room temperature, in Example 6, KZnF3:2mol%Yb 3+ X-ray powder diffraction pattern of nanocrystals. Detailed Implementation

[0051] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0052] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0053] Instruments and equipment:

[0054] The instrument used for powder diffraction characterization of the product in this embodiment of the invention is a MiniFlex2 manufactured by Rigaku, with a copper target radiation wavelength of λ = 0.154187 nm.

[0055] The instrument used for X-ray energy dispersive spectroscopy analysis of the product in this embodiment of the invention is model JEM-2010, manufactured by JEOL.

[0056] The instrument used for transmission electron microscopy (TEM) examination of the product in this embodiment of the invention is a TECNAI G. 2 F20, manufactured by FEI.

[0057] The instrument used for fluorescence emission spectroscopy and fluorescence lifetime characterization of the product in this embodiment of the invention is an FLS980 manufactured by Edinburgh, and the excitation source is a xenon lamp and a 980nm LD laser.

[0058] The instrument used to characterize the photon avalanche power dependence and time-resolved spectrum of the product in this embodiment of the invention is a Ti-U, manufactured by Nikon, and the excitation source is a 1064nm LD laser.

[0059] Example 1: KMgF3 with different particle sizes: 20 mol% Yb 3+ 2mol%Er 3+ Preparation of nanocrystals.

[0060] Weigh out 0.78 mmol Mg(CH3COO)2·H2O, 0.20 mmol Yb(CH3COO)3·4H2O, and 0.02 mmol Er(CH3COO)3·4H2O at room temperature. Add 8 mL oleic acid and 12 mL octadecene, mix well, and heat under a nitrogen atmosphere until dissolved, stirring thoroughly. Cool to room temperature, add 1.5 mmol of potassium hydrofluoric acid aqueous solution (1.5 mol / L), heat to a certain temperature under a nitrogen atmosphere, react for a certain time, cool to room temperature, and then precipitate and wash with ethanol by centrifugation to prepare KMgF3:20 mol% Yb with a specific particle size. 3+ 2mol%Er 3+ Nanocrystals are luminescent materials.

[0061] Specifically, the reaction temperatures and reaction times for different particle sizes are as follows: (a) 12nm: 280℃, 1h; (b) 17nm: 280℃, 2h; (c) 21nm: 290℃, 1h; (d) 30nm: 290℃, 2h.

[0062] Figure 1 The KMgF3:20mol%Yb with different particle sizes (12, 17, 21, and 30 nm) in Example 13+ 2mol%Er 3+ X-ray powder diffraction pattern of nanocrystals.

[0063] Figure 1 This indicates the different reaction conditions used to prepare KMgF3:20mol%Yb 3+ 2mol%Er 3+ The nanocrystals exhibit good crystallinity, consistent with the PDF standard card (JCPDS No. 018-1033) of cubic KMgF3 crystals, and no extra diffraction peaks appear, indicating that the nanocrystals prepared under different reaction conditions are all pure cubic KMgF3 phase.

[0064] Figure 2 The KMgF3:20mol%Yb with different particle sizes (12, 17, 21, and 30 nm) in Example 1 3+ 2mol%Er 3+ Transmission electron microscopy images of nanocrystals and their corresponding particle size statistics.

[0065] Figure 2 The results show that the nanocrystals prepared under different reaction conditions have good dispersibility and uniform morphology, with particle sizes of 12.1 nm, 17.0 nm, 21.3 nm and 30.8 nm, respectively.

[0066] Figure 3 The KMgF3:20mol%Yb with a particle size of 30nm in Example 1 3+ 2mol%Er 3+ (a) Ring-shaped dark-field scanning electron microscope, (b) single-particle energy loss, (c) F, (d) Mg, (e) K, (f) Yb, (g) Er and (h) superimposed distribution of the above elements.

[0067] Figure 3 This indicates that KMgF3:20mol%Yb 3+ 2mol%Er 3+ The nanocrystals contain potassium, magnesium, fluorine, and doped rare earth elements ytterbium and erbium, with rare earth ions clustering towards the center to form a structure similar to KMgF3:xmol%Ln. 3+ The KMgF3 core-shell structure shows that the brighter central region corresponds to the heavier rare earth elements in the nanocrystals, while the darker outer region corresponds to the lighter potassium, magnesium, and fluorine elements in the nanocrystals.

[0068] Figure 4 At room temperature and under 980 nm excitation, (a) KMgF3:20 mol% Yb with different particle sizes in Example 1 3+ 2mol%Er 3+ Nanocrystals, and (c,d)Er 3+of 4 F 9 / 2 Energy levels and 4 I 13 / 2 Fluorescence decay curves of energy levels, (e,f)Ho 3+ of 5 F4 and 5 Fluorescence decay curve of I6 level.

[0069] Figure 4 a, c, and d indicate that at 980 nm (excitation power density of 20 W / cm²), –2 Under excitation, KMgF3:20mol%Yb with different particle sizes 3+ 2mol%Er 3+ The nanocrystals exhibit bright red upconversion luminescence, and the emission spectrum shows Er 3+ The characteristic emission peaks at 521, 542, 653, and 1528 nm are attributed to Er, respectively. 3+ of 2 H 11 / 2 → 4 I 15 / 2 , 4 S 3 / 2 → 4 I 15 / 2 , 4 F 9 / 2 → 4 I 15 / 2 and 4 I 13 / 2 → 4 I 15 / 2 Electron transitions occur. As the nanocrystal size increases, surface fluorescence quenching weakens, the luminescence of the nanocrystals gradually increases, and fluorescence decay slows down.

[0070] Example 2: KMgF3 with different particle sizes: 20 mol% Yb 3+ 1mol%Ho 3+ Preparation of nanocrystals.

[0071] Weigh out 0.79 mmol Mg(CH3COO)2·H2O, 0.20 mmol Yb(CH3COO)3·4H2O, and 0.01 mmol Ho(CH3COO)3·4H2O at room temperature. Add 8 mL oleic acid and 12 mL octadecene, mix well, and heat under a nitrogen atmosphere until dissolved, stirring thoroughly. Cool to room temperature, add 1.5 mmol of potassium hydrofluoric acid aqueous solution (1.5 mol / L), heat to a certain temperature under a nitrogen atmosphere, react for a certain time, cool to room temperature, and then precipitate and wash with ethanol by centrifugation to prepare KMgF3:20 mol% Yb with a specific particle size. 3+ 1mol%Ho 3+ Nanocrystals are luminescent materials.

[0072] Specifically, the reaction temperatures and reaction times for different particle sizes are as follows: (a) 12nm: 280℃, reaction time 1h; (b) 17nm: 280℃, reaction time 2h; (c) 21nm: 290℃, reaction time 1h; (d) 30nm: 290℃, reaction time 2h.

[0073] Figure 4 b represents the KMgF3:20mol%Yb particle size ratio at room temperature and under 980nm excitation. (b) Examples 2: KMgF3:20mol%Yb with different particle sizes. 3+ 1mol%Ho 3+ Upconversion and downconversion luminescence spectra of nanocrystals.

[0074] Figure 4 b, e, f indicate that at 980 nm (excitation power density of 20 W / cm²), –2 Under excitation, KMgF3:20mol%Yb with different particle sizes 3+ 1mol%Ho 3+ The nanocrystals exhibit bright green upconversion luminescence, and the emission spectrum shows Ho 3+ The characteristic emission spikes at 545nm, 659nm, 750nm, and 1197nm are attributed to Ho, respectively. 3+ of 5 F4→ 5 I8 5 F5 → 5 I8 5 F4→ 5 I7 and 5 I6→ 5 Electronic transitions of I8. As the nanocrystal size increases, its specific surface area decreases, the fluorescence quenching effect weakens, the luminescence of the nanocrystals is enhanced, and the fluorescence lifetime is extended.

[0075] Example 3: Different Yb 3+ Doping concentration KMgF3:x mol% Yb 3+ Preparation of nanocrystals.

[0076] Weigh (1-x) mmol Mg(CH3COO)2·H2O and x mmol Yb(CH3COO)3·4H2O (x = 0, 0.01, 0.05, 0.1, 0.2, 0.3) at room temperature. Add 8 mL oleic acid and 12 mL octadecene, mix well, and heat under a nitrogen atmosphere until dissolved, stirring thoroughly. Cool to room temperature, add 1.5 mmol of potassium hydrofluoric acid aqueous solution (concentration 1.5 mol / L), heat to 290℃ under a nitrogen atmosphere, maintain the temperature for 2 h, and then cool to room temperature. Wash the precipitate with ethanol by centrifugation to obtain well-dispersed oil-soluble KMgF3:x mol% Yb. 3+Nanocrystals (x = 0, 1, 5, 10, 20, 30) are luminescent materials.

[0077] Figure 5 For different Yb in Example 3 3+ Doping concentration KMgF3:x mol% Yb 3+ X-ray powder diffraction patterns of nanocrystals (x = 0, 1, 5, 10, 20, 30).

[0078] Figure 5 This indicates that different Yb 3+ The KMgF3 nanocrystals with varying doping concentrations exhibited good crystallization, and their diffraction peaks were consistent with the PDF standard card (JCPDS No. 018-1033) for cubic KMgF3 crystals. With the increasing concentration of Yb... 3+ With increasing doping concentration, the peak width of the diffraction peaks of KMgF3 nanocrystals gradually narrows, while the particle size of the nanocrystals gradually increases; the position of the diffraction peaks gradually shifts towards smaller angles, indicating that Yb 3+ Replacement of smaller Mg 2+ The lattice sites cause lattice expansion.

[0079] Figure 6 In Example 3, (ac) represents different Yb. 3+ Doping concentration KMgF3:x mol% Yb 3+ The transmission electron microscope (df) images of the nanocrystals (x = 1, 10, 20) are the corresponding high-resolution transmission electron microscope images.

[0080] Figure 6 af indicates that as Yb 3+ As the doping concentration increases, the particle size of the nanocrystals gradually increases, indicating that rare earth ions can promote the growth and formation of nanocrystals; the lattice expansion of KMgF3 nanocrystals, with the lattice stripe width of the (110) crystal plane increasing from 0.27 nm to 0.29 nm, further indicates that Yb 3+ Replaced Mg 2+ The grid position.

[0081] Example 4: KMgF3:x mol%Tm 3+ Preparation of nanocrystals.

[0082] Weigh (1-x) mmol Mg(CH3COO)2·H2O and x mmol Tm(CH3COO)3·4H2O (x = 0.01, 0.03, 0.05) at room temperature. Add 8 mL oleic acid and 12 mL octadecene, mix well, and heat under a nitrogen atmosphere until dissolved, stirring thoroughly. Cool to room temperature, add 1.5 mmol of potassium hydrofluoric acid aqueous solution (concentration 1.5 mol / L), heat to 290 °C under a nitrogen atmosphere, maintain the temperature for 2 h, and cool to room temperature. Wash the precipitate with ethanol by centrifugation to obtain well-dispersible oil-soluble KMgF3:x mol%Tm 3+ Nanocrystals (x = 1, 3, 5).

[0083] Figure 7 At room temperature, in Example 4, KMgF3: 5 mol% Tm 3+ Upconversion emission spectra of nanocrystals under different excitation power densities at 1064 nm excitation.

[0084] Figure 7 This indicates that at 1064 nm (power density of 15.1 kW cm⁻¹), –2 Under excitation, KMgF3: 5 mol% Tm 3+ Nanocrystals exhibit Tm at 802nm 3+ ( 3 H4→ 3 The characteristic emission peak of H6) at a higher excitation power density (5×10⁶) 3 kW cm –2 Under excitation, in addition to the 802nm emission peak, Tm can also be observed. 3+ At 662nm ( 1 G4→ 3 F4) and 709nm 3 F 2,3 → 3 The characteristic emission peak at H6).

[0085] Figure 8 At room temperature, different Tm values ​​in Example 4 3+ Doping concentration KMgF3:x mol% Tm 3+ (x = 1, 3, 5), under 1064 nm excitation, (a) KMgF3:x mol%Tm 3+ In nanocrystals, Tm 3+ 802nm ( 3 H4→ 3 (a) Power dependence of upconversion luminescence at H6, the dashed line is the linear fit at the point where the slope of the nonlinear curve is the largest (excitation wavelength is 1064 nm); (b) KMgF3: xmol%Tm 3+The nonlinear curve of the nanocrystals was linearly fitted to show the relationship between the slope and the excitation power density.

[0086] Figure 8 Indicates Tm 3+ As the doping concentration increases from 1 mol% to 5 mol%, the ESA-CR energy cycling rate accelerates, KMgF3: x mol% Tm 3+ Tm in nanocrystals 3+ The maximum slope s of the curve relating luminescence intensity at 802 nm to excitation power density at 1064 nm, after linear fitting, increased from 23.4 to 27.0. Simultaneously, the threshold power density also increased from 25.6 kW cm⁻¹. -2 Reduced to 16.6kWcm -2 In KMgF3:x mol%Tm 3+ There is a clear threshold power in the nanocrystals. Beyond this threshold power, the emission intensity exhibits a nonlinear increase, which is consistent with the characteristics of photon avalanche, indicating that photon avalanche upconversion exists within them.

[0087] Figure 9 At room temperature, under 1064 nm excitation as in Example 4, KMgF3: 5 mol% Tm 3+ Time-resolved upconversion spectroscopy of nanocrystals.

[0088] Figure 9 This indicates that KMgF3: 5mol%Tm 3+ The rise time of the excited-state fluorescence lifetime of the nanocrystals gradually increases near the threshold power, reaching a peak at a threshold power of 16.6 kW cm⁻¹. -2 At the threshold power, the rise time of the excited-state lifetime is the longest at 281 ms. The rise time of the excited-state fluorescence lifetime is prolonged at the threshold power, further indicating that at KMgF3:5 mol% Tm 3+ Nanocrystals exhibit photon avalanche upconversion. Furthermore, in KMgF3:x mol%Tm 3+ In nanocrystals, the rise time of the excited-state fluorescence lifetime is shorter than that of conventional photon avalanche (several seconds to several minutes), indicating that in KMgF3:x mol%Tm 3+ In nanocrystals, Tm 3+ The photon avalanche response is faster.

[0089] Example 5: NaMgF3:5mol%Yb 3+ Preparation of nanocrystals.

[0090] Weigh 0.95 mmol Mg(CH3COO)2·H2O and 0.05 mmol Yb(CH3COO)3·4H2O at room temperature. Add 8 mL oleic acid and 12 mL octadecene, mix well, and heat under a nitrogen atmosphere until dissolved, stirring thoroughly. Cool to room temperature, then add 1.5 mmol of an aqueous solution of sodium hydrofluoric acid (1.5 mol / L). Heat to 290 °C under a nitrogen atmosphere and maintain at this temperature for 1 h, then cool to room temperature. Wash the precipitate with ethanol by centrifugation to obtain well-dispersed, oil-soluble NaMgF3:5 mol% Yb. 3+ Nanocrystals are luminescent materials.

[0091] Figure 10 At room temperature, in Example 5, NaMgF3:5 mol% Yb 3+ X-ray powder diffraction pattern of nanocrystals.

[0092] Figure 10 This indicates that the prepared NaMgF3:5mol%Yb 3+ The nanocrystals exhibit good crystallinity, consistent with the PDF standard card (JCPDS No. 900-3812) of orthorhombic NaMgF3 crystals, and no extra diffraction peaks appear, indicating that the prepared nanocrystals are pure orthorhombic NaMgF3 phase.

[0093] Example 6: KZnF3:2mol%Yb 3+ Preparation of nanocrystals.

[0094] Weigh 0.98 mmol Zn(CH3COO)2·H2O and 0.02 mmol Yb(CH3COO)3·4H2O at room temperature. Add 6 mL oleic acid and 15 mL octadecene, mix well, and heat under a nitrogen atmosphere until dissolved, stirring thoroughly. Cool to room temperature, then add 1.5 mmol of an aqueous solution of potassium hydrofluoric acid (1.5 mol / L). Heat to 290 °C under a nitrogen atmosphere and maintain at this temperature for 1 h, then cool to room temperature. Wash the precipitate with ethanol by centrifugation to obtain well-dispersed, oil-soluble KZnF3:2 mol% Yb. 3+ Nanocrystals are luminescent materials.

[0095] Figure 11 At room temperature, in Example 6, KZnF3:2mol%Yb 3+ X-ray powder diffraction pattern of nanocrystals.

[0096] Figure 11 This indicates that the prepared KZnF3:2mol%Yb 3+The nanocrystals exhibit good crystallinity, consistent with the PDF standard card (JCPDS No. 089-4110) of cubic KZnF3 crystals, and no extra diffraction peaks appear, indicating that the prepared nanocrystals are pure cubic KZnF3 phase.

[0097] The embodiments of the present invention have been described above by way of example. However, the scope of protection of the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A rare-earth-doped ABF3 perovskite-type luminescent nanomaterial, characterized in that, The general formula of the luminescent material is ABF3: x mol%Ln n+ In this context, A is selected from one of the alkali metals Li, Na, K, Rb, and Cs; B is selected from one of the alkaline earth metals or transition metals Mg, Ca, Sr, Ba, Mn, Zn, Cd, Co, Ni, and Cu; F represents fluorine, and Ln represents lanthanide rare earth elements. x mol% represents the percentage of lanthanide rare earth ions in the total moles of alkaline earth metals or transition metals and lanthanide rare earth elements, 1 ≤ x ≤80; n is 2 or 3; The luminescent material has a core-shell structure, wherein the central region is composed of rare earth elements and the outer region is composed of A, B and fluorine elements; The luminescent material can achieve high-order nonlinear photon avalanche upconversion at room temperature; The method for preparing the luminescent material includes: dissolving B salt, Ln salt and hydrofluoric acid A in an organic solvent, heating and reacting to obtain the rare earth-doped ABF3 perovskite nanoluminescent material; The B salt is selected from one of Mg(CH3COO)2, Ca(CH3COO)2, Sr(CH3COO)2 or Ba(CH3COO)2, Mn(CH3COO)2, Zn(CH3COO)2, Cd(CH3COO)2, Co(CH3COO)2, Cu(CH3COO)2 or Ni(CH3COO)2; The Ln salt is selected from one or more of La(CH3COO)3, Ce(CH3COO)3, Pr(CH3COO)3, Nd(CH3COO)3, Sm(CH3COO)3, Eu(CH3COO)3, Gd(CH3COO)3, Tb(CH3COO)3, Dy(CH3COO)3, Ho(CH3COO)3, Er(CH3COO)3, Tm(CH3COO)3, Yb(CH3COO)3, Lu(CH3COO)3, Y(CH3COO)3, and Sc(CH3COO)3.

2. The material according to claim 1, characterized in that, A is K or Na; B is Mg or Zn.

3. The material according to claim 1, characterized in that, The Ln n+ Selected from Ho 3+ Er 3+ Tm 3+ 、Tb 3+ Eu 3+ Ce 3 + 、Sm 3+ Dy 3+ 、Nd 3+ Pr 3+ Gd 3+ ,Sc 3+ Lu 3+ Yb 3+ Y 3+ La 3+ At least one of them.

4. The material according to claim 1, characterized in that, The luminescent material is KMgF3: 20 mol%Yb 3+ 2mol%Er 3+ KMgF3: 20 mol%Yb 3+ 1 mol%Ho 3+ KMgF3: 1mol%Yb 3+ KMgF3: 5mol%Yb 3+ KMgF3:10mol%Yb 3+ KMgF3: 20mol%Yb 3+ KMgF3: 30mol%Yb 3+ Or KMgF3: 1mol%Tm 3+ KMgF3: 3mol%Tm 3 + KMgF3: 5mol%Tm 3+ Or NaMgF3: 5mol%Yb 3+ Or KZnF3: 2mol%Yb 3+ .

5. The material according to claim 1, characterized in that, The particle size of the luminescent material is 5-200 nm.

6. The material according to claim 1, characterized in that, The luminescent material is a cubic phase or an orthorhombic phase.

7. The material according to claim 1, characterized in that, The heating reaction time is 1-240 min; the heating reaction temperature is 100-400 ºC.

8. The material according to claim 1, characterized in that, The organic solvent is selected from at least one of oleic acid, oleylamine, trioctylamine, and octadecene.

9. The material according to claim 1, characterized in that, The molar ratio of B salt to Ln salt is (1- y ) : y .

10. The material according to claim 1, characterized in that, The amount of hydrofluoric acid A used is 1 to 5 times the sum of the molar numbers of B salt and Ln salt.

11. The material according to claim 1, characterized in that, The method further includes: dispersing the rare earth-doped ABF3 perovskite nanoluminescent material in a non-polar organic solvent to obtain a rare earth-doped ABF3 perovskite nanoluminescent material solution.

12. The material according to claim 11, characterized in that, The nonpolar organic solvent is selected from at least one of n-hexane, cyclohexane, chloroform, dichloromethane, or toluene.

13. The application of the material according to any one of claims 1-12 in the fields of super-resolution imaging, single-molecule tracing, optical anti-counterfeiting and coding.

Images