Organic-inorganic hybrid light-emitting halide material as well as preparation method and application thereof

Abstract

The invention discloses an organic-inorganic hybrid light-emitting halide material as well as a preparation method and application thereof, and belongs to the technical field of light-emitting materials. The chemical general formula of the organic-inorganic hybrid luminescent halide material is AL6AC16, in the formula, A is lanthanide ions, and L is N, N '-dimethylurea or N, N'-diethyl urea. The invention also discloses a preparation method and application of the organic-inorganic hybrid luminescent halide material. The organic-inorganic hybrid luminescent halide material can stably exist in the atmospheric environment with the relative humidity smaller than 65%, the problem that an existing lanthanide-based organic-inorganic hybrid halide is poor in air stability and humidity stability is solved, and the organic-inorganic hybrid luminescent halide material is wide in application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of luminescent materials, and particularly relates to an organic-inorganic hybrid luminescent halide material, a preparation method thereof, and applications thereof. Background Art

[0002] In recent years, zero-dimensional (0D) halide perovskites have become a research hotspot in luminescent materials due to their excellent optoelectronic properties. Different from three-dimensional (3D) perovskites, 0D halide perovskites are composed of isolated metal halide octahedra (PbX6 3- , SbX6 3- , SnX6 3- etc., X = Cl, Br, I), and they are separated from each other by organic or inorganic cations. This unique structure hinders the migration of excitons, reduces non-radiative transitions, and achieves a relatively high photoluminescence quantum yield (PLQY). More importantly, the introduction of 0D halide perovskites effectively improves the structural stability and photoluminescence stability of the materials; due to the lack of a continuous metal halide framework, 0D halide perovskites have better wet, light, and thermal structural stabilities than 3D halide perovskites. In addition, organic cations play an important role in 0D halide perovskites, which can not only achieve the modulation of structural dimensions, but also enhance the structural stability through rich hydrogen bonds and van der Waals effects. These characteristics make 0D halide perovskites candidates for lighting, sensing, display, scintillation, and anti-counterfeiting applications.

[0003] Lanthanide elements are widely used in optoelectronic functional fields such as solid-state lighting, display devices, bioimaging, and anti-counterfeiting labels due to their unique 4f–4f transition mechanism, narrow-band emission characteristics, and long-lived excited states. Especially in the construction of luminescent materials with high color purity and high quantum efficiency, lanthanide ions have an irreplaceable position in the design of new functional materials. Recently, it has been found that 0D lanthanide halide perovskites (Cs3TbCl6, Rb3TbCl6, and Cs3CeBr6) have been developed for LEDs and scintillators, with ultra-high PLQY. In addition, by incorporating organic cations into lanthanide ions, lanthanide-based organic-inorganic hybrid halides have obtained high PLQY and good mechanical processing properties. However, similar to 0D lanthanide halide perovskites, lanthanide-based organic-inorganic hybrid halides also have serious air / humidity instabilities. Especially, the 3- [LnCl6] (Ln = lanthanide ion) structural unit is extremely prone to hydrolysis and structural collapse after exposure to air, which in turn leads to a sharp decay in luminescence performance, severely limiting their application in devices in open environments.

[0004] To isolate the influence of moisture on the structure, early lanthanide-based organic-inorganic hybrid halide materials were usually synthesized in a moisture-free environment. In recent years, preparation methods such as temperature-assisted solution evaporation method and temperature-assisted anti-crystallization method have also been developed for lanthanide-based organic-inorganic hybrid halide materials. However, these methods usually have complex reaction conditions and strong dependence on equipment, making it difficult to achieve large-scale green synthesis.

[0005] Therefore, there is an urgent need to develop a molecular-scale waterproof strategy with clear structure, controllable mechanism, simple operation and universality, so that rare-earth halide-based luminescent materials can achieve long-term efficient and stable luminescence in air without sacrificing their excellent optical properties. At the same time, this strategy should have good scalability and be applicable to different types of rare-earth ions and crystal coordination environments to meet the diverse needs in practical device applications. Summary of the Invention

[0006] The problem to be solved by the present invention is to provide an organic-inorganic hybrid luminescent halide material, its preparation method and application to solve the problem of poor air stability and humidity stability of existing lanthanide-based organic-inorganic hybrid halides.

[0007] The technical solution adopted to solve its technical problem is an organic-inorganic hybrid luminescent halide material, and the chemical general formula of the organic-inorganic hybrid luminescent halide material is AL6ACl6, where A is a lanthanide ion and L is N,N'-dimethylurea or N,N'-diethylurea.

[0008] The beneficial effect of the present invention adopting the above technical solution is that the organic-inorganic hybrid luminescent halide material of the present invention has good air stability and humidity stability, and its action mechanism mainly lies in that: the organic ligand L in the chemical general formula has a molecular structure with high symmetry, and there are two different functional groups (urea group and amino group) on the upper and lower sides of the alkane chain; the urea functional group contained therein is negatively charged and forms [AL6] 3+ cation with some isolated lanthanide ions (A ions), while the other part of A ions and chloride ions form a negatively charged [ACl6] 3- octahedron to balance the charge, and at the same time is attracted by the positively charged amino group to form a hydrogen bond; [AL6] 3+ and [ACl6] 3- octahedrons are alternately arranged to form a zero-dimensional perovskite-like structure; further, the organic ligand L constructs two pseudo-molecular cage-like structures, which have a spatial separation and protection effect on isolated A ions and [ACl6] 3- octahedrons; at the same time, the rich hydrogen bond interactions between the organic ligands L hinder the erosion of water molecules in the air. When L is N,N'-diethylurea, the extended alkane chain makes the organic-inorganic hybrid lanthanide luminescent halide material have better air stability.

[0009] Preferably, the lanthanide ion is Tb 3+ , Eu 3+ or Ce 3+ .

[0010] Preferably, the organic-inorganic hybrid luminescent halide material has a pseudo-molecular cage structure.

[0011] The present invention also provides a preparation method of the above-mentioned organic-inorganic hybrid luminescent halide material, using L and the compound ACl3·xH2O as raw materials, and preparing by a solution evaporation method or a mechanical grinding method.

[0012] Preferably, the compound ACl3·xH2O is TbCl3·6H2O, EuCl3·6H2O or CeCl3·7H2O.

[0013] Preferably, the solution evaporation method includes the following steps: Using L and the compound ACl3·xH2O as raw materials, adding a solvent, mixing evenly, and then standing for solvent evaporation to obtain crystals of the organic-inorganic hybrid luminescent halide material.

[0014] More preferably, the molar ratio of ACl3·xH2O to L is 1:3; the solvent is methanol, ethanol or acetone; the ratio of the solvent volume to the total mass of ACl3·xH2O and L is 10-20 mL:1 g.

[0015] Preferably, the mechanical grinding method includes the following steps: Using L and the compound ACl3·xH2O as raw materials, dropping a solvent and then grinding to obtain polycrystalline powder of the organic-inorganic hybrid luminescent halide material.

[0016] More preferably, the molar ratio of ACl3·xH2O to L is 1:3; the solvent is methanol, ethanol or acetone; the ratio of the solvent volume to the total mass of ACl3·xH2O and L is 0.05-0.2 mL:1 g; the grinding time is 8-12 min.

[0017] The present invention also provides the application of the above-mentioned organic-inorganic hybrid luminescent halide material in the preparation of optoelectronic devices, display and anti-counterfeiting.

[0018] The present invention has the following beneficial effects: (1) The organic-inorganic hybrid luminescent halide material of the present invention can stably exist in an atmospheric environment with a relative humidity of less than 65%. Its pseudo-molecular cage structure greatly improves the structural stability of the material; the pseudo-molecular cage structure formed by the organic ligands in the structure has an effect on the isolated lanthanide ions and [ACl6] 3-The octahedron forms a good coating, greatly enhancing the air stability of the material and solving the problem of poor air stability of lanthanide-based organic-inorganic hybrid luminescent halide materials.

[0019] (2) The organic-inorganic hybrid luminescent halide material of the present invention can directly prepare crystals and polycrystalline powders by solution evaporation method and mechanical grinding method in an atmospheric atmosphere, breaking through the limitation that traditional lanthanide organic-inorganic hybrid halide materials need to be prepared at high temperature; the preparation method is simple and can meet the diverse needs in actual device applications. Description of the Drawings

[0020] Figure 1 It is a process diagram for the mechanical grinding preparation of [Tb(DEU)6]TbCl6 in Example 2; Figure 2 It is an analysis diagram of the bonding situation; among them, (a) is the electrostatic potential distribution diagram of N,N'-dimethylurea molecule and N,N'-diethylurea molecule; (b) is the specific bonding situation diagram of N,N'-diethylurea molecule inside [Tb(DEU)6]TbCl6 in Example 1; Figure 3 It is the crystal structure diagram of [Tb(DMU)6]TbCl6 in Example 3; Figure 4 It is the crystal structure diagram of [Tb(DEU)6]TbCl6 in Example 1; Figure 5 It is the structure diagrams of two pseudo-molecular cages in the crystal of [Tb(DEU)6]TbCl6 in Example 1; among them, (a) is the structure diagram of cage 1; (b) is the structure diagram of cage 2; Figure 6 It is the percentage volume calculation diagram; among them, (a) is the percentage volume calculation diagram of [Tb(DMU)6]TbCl6 in Example 3; (b) is the percentage volume calculation diagram of [Tb(DEU)6]TbCl6 in Example 1; Figure 7 It is the Hirshfeld surface analysis diagram and two-dimensional fingerprint diagram of [Tb(DEU)6]TbCl6 in Example 1; among them, (a) is the schematic diagram of the molecular structure; (b) is the total distance distribution diagram; (c) is the H···H distribution diagram; (d) is the H···Cl distribution diagram; Figure 8 It is the Hirshfeld surface analysis diagram and two-dimensional fingerprint diagram of [Tb(DMU)6]TbCl6 in Example 3; among them, (a) is the schematic diagram of the molecular structure; (b) is the total distance distribution diagram; (c) is the H···H distribution diagram; (d) is the H···Cl distribution diagram; Figure 9It is an XRD diffraction data graph; among them, (a) is [Tb(DEU)6]TbCl6 of Example 1; (b) is [Tb(DMU)6]TbCl6 of Example 3; (c) is (DMA)4TbCl7 of Comparative Example 1. Figure 10 It is a graph of the change in the photoluminescence quantum yield of [Tb(DEU)6]TbCl6 of Example 1. Detailed implementation manners

[0021] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0022] Example 1 An organic-inorganic hybrid luminescent halide material with a chemical general formula of [Tb(DEU)6]TbCl6, where DEU is C5H 12 N2O.

[0023] This example also includes a preparation method of the above-mentioned organic-inorganic hybrid luminescent halide material, including the following steps: (1) Weigh 0.174 g of N,N'-diethylurea and 0.187 g of TbCl3·6H2O, and add 5 mL of methanol thereto and mix well to obtain a clear mixed solution; (2) Place the mixed solution in a fume hood for methanol volatilization for 5 h to obtain transparent crystals of the organic-inorganic hybrid luminescent halide material, namely [Tb(DEU)6]TbCl6 crystals.

[0024] Example 2 An organic-inorganic hybrid luminescent halide material with a chemical general formula of [Tb(DEU)6]TbCl6, where DEU is C5H 12 N2O.

[0025] This example also includes a preparation method of the above-mentioned organic-inorganic hybrid luminescent halide material, including the following steps: Weigh 0.174 g of N,N'-diethylurea and 0.187 g of TbCl3·6H2O and place them in a mortar, then drop 0.05 mL of methanol into it and grind for 10 min to obtain polycrystalline powder of the organic-inorganic hybrid luminescent halide material, namely polycrystalline powder of [Tb(DEU)6]TbCl6.

[0026] The mechanical grinding preparation process is as Figure 1 shown, indicating that the material can be rapidly ground and synthesized under room temperature and atmospheric atmosphere.

[0027] Example 3 An organic-inorganic hybrid luminescent halide material with the chemical general formula [Tb(DMU)6]TbCl6, where DMU is C3H8N2O.

[0028] This example also includes a preparation method for the above-mentioned organic-inorganic hybrid luminescent halide material, which includes the following steps: (1) Weigh 0.132 g of N,N'-dimethylurea and 0.187 g of TbCl3·6H2O, and add 5 mL of methanol thereto and mix well to obtain a clear mixed solution; (2) Place the mixed solution in a fume hood for methanol volatilization for 5 h to obtain transparent [Tb(C3H8N2O)6]TbCl6 crystals, denoted as [Tb(DMU)6]TbCl6 crystals.

[0029] Example 4 An organic-inorganic hybrid luminescent halide material with the chemical general formula [Tb(DMU)6]TbCl6, where DMU is C3H8N2O.

[0030] This example also includes a preparation method for the above-mentioned organic-inorganic hybrid luminescent halide material, which includes the following steps: Weigh 0.132 g of N,N'-dimethylurea and 0.187 g of TbCl3·6H2O and place them in a mortar, then drop 0.05 mL of methanol into it and grind for 10 min to obtain polycrystalline powder of the organic-inorganic hybrid luminescent halide material, which is polycrystalline powder of [Tb(DMU)6]TbCl6.

[0031] Example 5 An organic-inorganic hybrid luminescent halide material with the chemical general formula [Eu(DEU)6]EuCl6, where DEU is C5H 12 N2O.

[0032] This example also includes a preparation method for the above-mentioned organic-inorganic hybrid luminescent halide material, which includes the following steps: (1) Weigh 0.174 g of N,N'-diethylurea and 0.183 g of EuCl3·6H2O, and add 5 mL of methanol thereto and mix well to obtain a clear mixed solution; (2) Place the mixed solution in a fume hood for methanol volatilization for 5 h to obtain transparent crystals of the organic-inorganic hybrid luminescent halide material, which are [Eu(DEU)6]EuCl6 crystals.

[0033] Example 6 An organic-inorganic hybrid luminescent halide material with the chemical general formula [Eu(DMU)6]EuCl6, where DMU is C3H8N2O.

[0034] This embodiment also includes a preparation method of the above-mentioned organic-inorganic hybrid luminescent halide material, which comprises the following steps: (1) Weigh 0.132 g of N,N'-dimethylurea and 0.183 g of EuCl3·6H2O, and add 5 mL of methanol thereto and mix well to obtain a clear mixed solution; (2) Place the mixed solution in a fume hood to volatilize methanol for 5 h to obtain crystals of the transparent organic-inorganic hybrid luminescent halide material, namely [Eu(DMU)6]EuCl6 crystals.

[0035] Example 7 An organic-inorganic hybrid luminescent halide material with a chemical general formula of [Ce(DEU)6]CeCl6, where DEU is C5H 12 N2O.

[0036] This embodiment also includes a preparation method of the above-mentioned organic-inorganic hybrid luminescent halide material, which comprises the following steps: (1) Weigh 0.174 g of N,N'-diethylurea and 0.186 g of CeCl3·6H2O, and add 5 mL of methanol thereto and mix well to obtain a clear mixed solution; (2) Place the mixed solution in a fume hood to volatilize methanol for 5 h to obtain crystals of the transparent organic-inorganic hybrid luminescent halide material, namely [Ce(DEU)6]CeCl6 crystals.

[0037] Example 8 An organic-inorganic hybrid luminescent halide material with a chemical general formula of [Ce(DMU)6]CeCl6, where DMU is C3H8N2O.

[0038] This embodiment also includes a preparation method of the above-mentioned organic-inorganic hybrid luminescent halide material, which comprises the following steps: (1) Weigh 0.132 g of N,N'-dimethylurea and 0.187 g of CeCl3·6H2O, and add 5 mL of methanol thereto and mix well to obtain a clear mixed solution; (2) Place the mixed solution in a fume hood to volatilize methanol for 5 h to obtain crystals of the transparent organic-inorganic hybrid luminescent halide material, namely [Ce(DMU)6]CeCl6 crystals.

[0039] Comparative Example 1 An organic-inorganic hybrid luminescent halide material with a chemical general formula of (DMA)4TbCl7, where DMA is a dimethylamine cation with a chemical formula of CH3NH2CH3.

[0040] This comparative example also includes the preparation method of the above-mentioned organic-inorganic hybrid luminescent halide material, which includes the following steps: Weigh 0.187 g of TbCl3·6H2O and place it in a mixed solution of 5 mL of hydrochloric acid and 310 μL of N,N-dimethylformamide. Heat the mixed solution to 180 °C and keep it for 5 min, and then cool it to room temperature to obtain (DMA)4TbCl7 crystals.

[0041] Experimental example 1. Analysis of bonding situation Analyze the electrostatic potential distribution of N,N'-dimethylurea molecules and N,N'-diethylurea molecules and the specific bonding situation of N,N'-diethylurea molecules inside the [Tb(DEU)6]TbCl6 crystal in Example 1. The results are as Figure 2 shown.

[0042] From Figure 2 it can be seen that both N,N'-dimethylurea molecules and N,N'-diethylurea molecules are amphiphilic molecules, with positively electropositive ends and negatively electropositive ends located on both sides of the alkane chain, which is conducive to attracting isolated Tb 3+ ions with positive charges and [TbCl6] 3- octahedrons with negative charges respectively.

[0043] 2. Material structure analysis Analyze the crystal structures of [Tb(DEU)6]TbCl6 crystals in Example 1 and [Tb(DMU)6]TbCl6 crystals in Example 3. The results are as Figures 3 - 8 shown.

[0044] From Figures 3 - 4 it can be seen that the materials prepared in Example 1 and Example 3 are both typical zero-dimensional crystal structures, and the central Tb 3+ is surrounded by six organic ligands (N,N'-dimethylurea molecules or N,N'-diethylurea molecules) to form a six-coordinate positive ion cage; the organic ligands also constitute a hydrophobic wrapping structure for [TbCl6] 3- to form a shielding.

[0045] It can be clearly seen from the structure of [Tb(DEU)6]TbCl6 in Example 1 that there are pseudo-molecular cage structures, denoted as cage 1 and cage 2. From Figure 5 it can be seen that it shows that both cage 1 and cage 2 are composed of six N,N'-diethylurea molecules, but the N,N'-diethylurea molecules of the two pseudo-molecular cages have different orientations.

[0046] The percentage volume (%Vbur) of [Tb(DEU)6]TbCl6 in Example 1 and [Tb(DMU)6]TbCl6 in Example 3 is as Figure 6shown; Hirshfeld surface analysis is as Figure 7 and Figure 8 shown.

[0047] As can be seen from Figure 6 , the percentage volumes of [Tb(DEU)6] 3+ and [Tb(DMU)6] 3+ are as high as 93.4% and 94.5% respectively, indicating that the organic ligands have a high coverage of the isolated Tb 3+ ions. As can be seen from Figures 7 - 8 , both the [Tb(DEU)6]TbCl6 and [Tb(DMU)6]TbCl6 systems are mainly dominated by hydrogen bond interactions, enhancing the crystal density; at the same time, [Tb(DEU)6]TbCl6 exhibits stronger H···H interactions than [Tb(DMU)6]TbCl6.

[0048] 3. XRD Diffraction Analysis XRD diffraction analysis was performed on [Tb(DEU)6]TbCl6 of Example 1, [Tb(DMU)6]TbCl6 of Example 3, and (DMA)4TbCl7 of Comparative Example 1 using an X-ray diffractometer (Rigaku D / MAX-r, CuKα radiation source (λ = 1.54184 Å), relative humidity 30 - 40%). The results are as Figure 9 shown.

[0049] By comparing the XRD patterns at different storage times (storage environment: atmospheric atmosphere with relative humidity of 55 - 65%), the structural stability of different materials can be evaluated. As can be seen from Figure 9 , the diffraction peak positions of [Tb(DEU)6]TbCl6 of Example 1 can still remain stable after 3 months of storage, indicating its good structural stability; the diffraction peaks of [Tb(DMU)6]TbCl6 of Example 3 change after 3 days of storage, and its structural stability is slightly worse than that of [Tb(DEU)6]TbCl6; while the spectrum of (DMA)4TbCl7 of Comparative Example 1 shows displacement and a large number of fluctuations after 2 hours of storage, with poor stability.

[0050] 4. Measurement of Photoluminescence Quantum Yield The change in the photoluminescence quantum yield (PLQY) value of [Tb(DEU)6]TbCl6 of Example 1 was measured using a fluorescence spectrometer (Edinburgh FS-5, relative humidity 30 - 40%). The results are as Figure 10 shown.

[0051] As can be seen from Figure 10It can be seen that [Tb(DEU)6]TbCl6 of Example 1 can stably exist for up to 3 months in an atmospheric atmosphere with a relative humidity of 55-65%, having good air stability and solving the problem that traditional lanthanide-based organic-inorganic hybrid luminescent halide materials cannot stably exist in the atmospheric environment.

[0052] The present invention has been described according to the above embodiments. It should be understood that the above embodiments do not limit the present invention in any form. Any technical solutions obtained by using equivalent replacements or equivalent transformations fall within the scope of the present invention.

Claims

1. An organic-inorganic hybrid luminescent halide material, characterized in that, The chemical general formula of the organic-inorganic hybrid luminescent halide material is AL6ACl6, where A is a lanthanide ion and L is N,N'-dimethylurea or N,N'-diethylurea.

2. The organic-inorganic hybrid luminescent halide material according to claim 1, wherein The lanthanide ion is Tb 3 + , Eu 3+ or Ce 3+ .

3. The organic-inorganic hybrid luminescent halide material according to claim 1, wherein The organic-inorganic hybrid luminescent halide material has a pseudo-molecular cage structure.

4. The preparation method of the organic-inorganic hybrid luminescent halide material according to any one of claims 1 to 3, characterized in that, It is prepared by using L and the compound ACl3·xH2O as raw materials through the solution evaporation method or the mechanical grinding method.

5. The preparation method of the organic-inorganic hybrid luminescent halide material according to claim 4, characterized in that, The compound ACl3·xH2O is TbCl3·6H2O, EuCl3·6H2O or CeCl3·7H2O.

6. The preparation method of the organic-inorganic hybrid luminescent halide material according to claim 4, characterized in that, The solution evaporation method includes the following steps: Using L and the compound ACl3·xH2O as raw materials, adding a solvent, mixing evenly, and then standing for solvent evaporation to obtain the crystal of the organic-inorganic hybrid luminescent halide material.

7. The preparation method of the organic-inorganic hybrid luminescent halide material according to claim 6, characterized in that, The molar ratio of ACl3·xH2O to L is 1:3; the solvent is methanol, ethanol or acetone; the ratio of the solvent volume to the total mass of ACl3·xH2O and L is 10 - 20 mL:1 g.

8. The preparation method of the organic-inorganic hybrid luminescent halide material according to claim 4, characterized in that, The mechanical grinding method includes the following steps: Using L and the compound ACl3·xH2O as raw materials, dropping a solvent and then grinding to obtain the polycrystalline powder of the organic-inorganic hybrid luminescent halide material.

9. The preparation method of the organic-inorganic hybrid luminescent halide material according to claim 8, characterized in that, The molar ratio of ACl3·xH2O to L is 1:3; the solvent is methanol, ethanol or acetone; the ratio of the solvent volume to the total mass of ACl3·xH2O and L is 0.05 - 0.2 mL:1 g; the grinding time is 8 - 12 min.

10. Application of the organic-inorganic hybrid luminescent halide material according to any one of claims 1 to 3 in the preparation of optoelectronic devices, display and anti-counterfeiting.

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