An ab co-doped manganese ion halide nanomaterial and a synthesis method thereof

Abstract

The application relates to a synthesis method of AB co-doped manganese ion halide nanomaterials, which comprises the following steps: 1) mixing raw materials such as cesium bromide, A-site dopant raw materials and B-site dopant raw materials, carrying out surface activation treatment after mixing, and then carrying out high-energy ball milling to obtain a mixture; 2) adding the mixture into a mixed solution of a reaction solvent and a ligand, and carrying out reaction under the assistance of ultraviolet light to realize ligand passivation, so as to obtain a reaction product; 3) carrying out silica coating on the reaction product to obtain superparamagnetic particles; and 4) carrying out drying, ball milling and static electricity elimination treatment on the superparamagnetic particles to obtain AB co-doped manganese ion halide nanomaterials. The application synthesizes AB co-doped manganese ion metal halides with high purity by adopting a solid-phase method, and the luminous intensity is improved compared with common manganese ion metal halide nanomaterials.

Description

Technical Field

[0001] This invention relates to the field of metal halide luminescent materials technology, specifically to an AB-site co-doped manganese ion halide nanomaterial and its synthesis method. Background Technology

[0002] Inorganic lead halide perovskites CsPbX3 (X = Cl, Br, I) have broad application prospects in light-emitting devices and photovoltaic devices due to their advantages such as high fluorescence quantum yield, tunable band gap, and high absorption coefficient. However, because the heavy metal lead is toxic and can harm the environment and organisms, the development of lead-free perovskites and their derivative materials has become a research hotspot. Manganese ion metal halide materials have diverse structures, good luminescent properties, and do not contain the heavy metal Pb. 2+ It has great application prospects in the fields of micro LED devices and optoelectronic devices. However, its synthesis technology is currently immature, with high requirements for experimental environment, long cycle and high temperature conditions, and sometimes the reaction products are accompanied by the formation of some other impurities. At the same time, its luminous intensity still needs to be improved compared with inorganic lead halide perovskites. At present, most studies use alkali metal element doping or A-site pure organic manganese ion metal halides.

[0003] Currently, the most studied structures are Cs1MnX3, Cs2MnX4, and Cs3MnX5, and the stability of the central atom can be analyzed using DFT calculations. Mechanical ball milling is a traditional powder-making technology, widely used but inefficient and prone to causing severe media pollution. Furthermore, mechanical energy alone is insufficient to induce material activation, phase transitions, and reactions, making precise control of material structure difficult, and hindering the synthesis of some compounds. Mechanochemical synthesis (i.e., all-solid-phase synthesis) has become a highly attractive synthetic method in recent years. This method uses mechanical energy to activate raw materials, alter their structure, and induce chemical reactions to form new phases. It is simple, energy-efficient, and environmentally friendly. Combining the luminescence principle of manganese ion metal halides, increasing the Mn... 2+ The spacing between atoms can improve luminescence performance. Alkaline earth metal ions have characteristics such as small radius and strong bonding. Some can dope and replace the central atom, increasing crystallinity and limiting grain growth; others can squeeze into the inter-lattice space due to their small radius, increasing the distance between the central atoms.

[0004] In terms of process, most synthesis methods for manganese ion metal halide materials employ liquid-phase methods, such as evaporation crystallization and hot injection. These methods require demanding experimental environments, have long cycles, and necessitate high-temperature conditions. Sometimes, the reaction products are accompanied by the formation of multiple phases, leading to a decrease in the purity of the target product and making it difficult to achieve reproducible and mass production of high-quality nanocrystals. Therefore, developing an environmentally friendly, simple, and easy-to-implement synthesis method suitable for large-scale production is of great significance. Summary of the Invention

[0005] The purpose of this invention is to reduce the synthesis difficulty of manganese ion halide luminescent materials and improve their luminescence performance. This invention discloses an AB-site co-doped manganese ion halide nanomaterial and its synthesis method. The specific scheme is as follows:

[0006] A method for synthesizing AB-site co-doped manganese ion halide nanomaterials includes the following steps:

[0007] 1) Cesium bromide, manganese bromide, A-site dopant raw materials, and B-site dopant raw materials are mixed, and then surface activated and high-energy ball milled to obtain a mixture; wherein the A-site dopant raw material is selected from 1-ethyl-2,3-dimethylimidazolium bromide, tetraphenylphosphine bromide, and 1-butyl-1-methylpiperidinium bromide; the B-site dopant raw material is selected from alkaline earth metal bromide raw materials;

[0008] 2) The mixture is added to a mixed solution of the reaction solvent and ligands, and the reaction is carried out under ultraviolet light to passivate the ligands and obtain the reactants;

[0009] 3) The reactants are coated with silica to obtain superparamagnetic particles;

[0010] 4) The superparamagnetic particles were dried, ball-milled and destatically removed to obtain AB-site co-doped manganese halide nanomaterials.

[0011] Preferably, in step 1), the B-site dopant raw material is selected from MgBr2·6H2O, CaBr2·2H2O, SrBr2·6H2O, and BaBr2·2H2O. The B-site dopant raw material is first continuously dried by microwave in an H2 gas flow before being mixed with the other raw materials.

[0012] Preferably, the B-site dopant is MgBr2·6H2O, and the A-site dopant is 1-ethyl-2,3-dimethylimidazolium bromide.

[0013] Preferably, in step 1), the surface activation treatment is performed using cold arc air plasma jet treatment.

[0014] Preferably, in step 2), the reaction solvent is toluene and the ligand is oleic acid.

[0015] Preferably, in step 3), the method of silica encapsulation is to add the reactants to an aqueous cyclohexane system and then introduce TEOS for silica encapsulation.

[0016] This invention also claims protection for AB-site co-doped manganese halide nanomaterials prepared according to the method of this invention.

[0017] Preferably, the molecular formula of the nanomaterial is xMg:(Cs) 0.85 EMMIM 0.15The value of x in 3MnBr5 is 5%-15%. Based on this molecular formula, the feed ratio is determined, and the synthesized halide nanomaterials have high purity, few impurities, and good luminescent properties.

[0018] Further preferably, the value of x is 10%.

[0019] Existing manganese ion metal halide materials are mostly doped by replacing Mn with one or two ions. 2+ This invention improves the optical performance of manganese ion metal halide materials by using large organic groups for A-site doping and small-radius alkaline earth metal elements for B-site doping, thus significantly enhancing the luminescence performance and stability of manganese ion metal halide materials. Therefore, this invention is helpful in expanding the application range of manganese ion metal halide materials.

[0020] The main objective of this invention is to refine the synthesis process. By using plasma-assisted ball milling, raw material pretreatment, and product posttreatment, manganese ion metal halide materials with good luminescence performance and high stability were synthesized. The manganese ion metal halide after AB site co-doping has a significantly broadened luminescence range and also has good luminescence performance and stability, showing great application prospects in the fields of micro LED devices and optoelectronic devices.

[0021] This invention uses DFT calculations to screen for the optimal manganese ion metal halide structure and determine the feed ratio. Then, the alkaline earth metal raw materials are pretreated, and high-purity AB-site co-doped manganese ion metal halides are synthesized using a solid-state method. An electrostatic discharger is used to eliminate static electricity in the synthesized AB-site co-doped manganese ion metal halide. This refines the process, repairs defects on the nanocrystal surface, and creatively studies the effects of adding organic groups and alkaline earth metal elements on the luminescence properties of manganese ion metal halide materials. It not only regulates the structure to stabilize the system but also broadens the luminescence range, possessing both research and practical significance.

[0022] This invention combines organic groups, alkaline earth metals, and manganese ion metal halide doping. The A-site dopant group consists of a large-radius organic group, and the B-site Mn-based dopant ion consists of alkaline earth metal ions and transition metal ions. It utilizes the large molecular diameter of the organic groups, combined with the inherent luminescence of the manganese ion metal halide host and the transition metal Mn... 2+ and alkaline earth metal Mg 2+ Ba 2+ The light emitted by these particles produces an excellent luminescent effect.

[0023] The AB-site co-doped manganese halide nanomaterials containing alkaline earth metal elements and organic groups synthesized in this invention exhibit improved luminescence intensity, enhanced temperature response, and good stability compared to ordinary manganese halide nanomaterials. They possess broad application potential in multicolor fluorescence emission, detection, photoelectric detection, and temperature sensing. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] Figure 1 This is a schematic diagram of the method flow of the present invention.

[0026] Figure 2 The XRD patterns of the halide nanomaterials obtained in Examples 1, 2, and 3 are shown.

[0027] Figure 3 The absorption spectra and band gap spectra of the halide nanomaterials obtained in Examples 1, 2, and 3 are shown.

[0028] Figure 4 The PL spectra of the halide nanomaterials obtained in Examples 1, 2, 3 and Comparative Example 1 are shown.

[0029] Figure 5 This is a photograph of the luminescent halide nanomaterials obtained in Example 1. Detailed Implementation

[0030] The present invention will now be clearly described in conjunction with specific embodiments. This description is merely illustrative and is not intended to limit the scope of the invention. Any modifications, equivalent substitutions, or improvements made by those skilled in the art based on the embodiments of the present invention without inventive effort to obtain all other embodiments should be included within the scope of protection of the present invention.

[0031] Example 1

[0032] (1) First-principles (DFT) simulation calculation of manganese ion metal halides: The optimal structure of manganese ion metal halides is calculated using DFT simulation to select the basic structure for doping. Using tetrahedral factor, octahedral factor, differences in crystal structure, changes in precursor formation energy, and the calculated DFT energy of each structure, a suitable structure is selected for doping from Cs1MnX3, Cs2MnX4, and Cs3MnX5 (X = Cl, Br, I). This project intends to select the Cs3MnX5 (X = Cl, Br, I) structure as the basic structure for doping;

[0033] (2) Screening of dopant elements through DFT simulation: The structure and properties of manganese ion metal halides were simulated to determine the raw materials for synthesizing manganese ion metal halides. Considering factors such as tetrahedral factor, lattice constant differences, similar ionic radii at substitution sites, similar crystal structures, similar electronegativity, similar valence states, Goldschmid tolerance factor, size disorder factor, and valence electron concentration, suitable alkaline earth metal ions and organic macromolecules for doping were calculated and selected. The calculation results show that Mg can be selected. 2+ Ca 2+ 、Sr 2+ Ba 2+ Alkaline earth metal ions are preferred. This project plans to select MgBr2·6H2O, CaBr2·2H2O, SrBr2·6H2O, BaBr2·2H2O, 1-ethyl-2,3-dimethylimidazolium bromide, tetraphenylphosphine bromide, and 1-butyl-1-methylpiperidinium bromide as raw materials for the preparation of AB co-doped manganese metal ions.

[0034] according to Figure 1 As shown, follow these steps:

[0035] (3) Pretreatment of raw materials: The chemical formula of the manganese ion metal halide material is Cs3MnX5. In a glove box, MgBr2·6H2O and 1-ethyl-2,3-dimethylimidazolium bromide were weighed. First, the MgBr2·6H2O raw material was continuously dried in a microwave oven under H2 gas flow at a drying temperature of 380℃. Then, it was mixed with CsBr, 1-ethyl-2,3-dimethylimidazolium bromide and manganese bromide and added to a ball mill jar. This example is used to synthesize 10% Mg:(Cs 0.85 EMMIM 0.15 )3MnBr5, the proportion of raw materials input is based on the target product;

[0036] (4) Cold arc air plasma jet treatment to activate powder in ball mill jar: Use cold arc air plasma jet spray gun to treat powder in ball mill jar for 10 min to activate powder surface;

[0037] (5) High-energy ball milling process for preparing manganese ion metal halide luminescent materials co-doped at AB sites: After activation, the ball milling jar is transferred to a high-energy ball mill for ball milling for 20 minutes at a speed of 875 rpm;

[0038] (6) Ligand passivation process of AB site co-doped manganese ion metal halide luminescent material: The ball-milled powder is added to a mixed solution of the reaction solvent toluene and the ligand oleic acid, and the reaction is carried out for 30 min under ultraviolet light to achieve ligand passivation.

[0039] (7) Silica encapsulation process of AB-site co-doped manganese ion metal halide luminescent material. Weigh 50 ml of cyclohexane and prepare a 50 ml mixture of cyclohexane and 30% aqueous solution. After ball milling, transfer the milling jar to a fume hood, open the milling jar, add the mixed solution, and introduce TEOS to form silica-encapsulated manganese ion metal halide superparamagnetic particles;

[0040] (8) Electrostatic elimination process of AB site co-doped manganese ion metal halide luminescent material. The coated nanoparticles were placed in a vacuum drying oven and dried at 70°C for 420 min. After drying, they were ground into powder and then taken out and electrostatic elimination was performed on them using an electrostatic eliminator to improve their dispersibility.

[0041] (9) The prepared sample was analyzed and characterized to determine its phase composition and luminescence properties.

[0042] Example 2

[0043] This example is used to synthesize 5% Mg:(Cs) 0.85 EMMIM 0.15 The proportion of raw materials used is based on the target product; the rest of the process is the same as in Example 1.

[0044] Example 3

[0045] This example is used to synthesize 15% Mg:(Cs) 0.85 EMMIM 0.15 The proportion of raw materials used is based on the target product; the rest of the process is the same as in Example 1.

[0046] Example 4

[0047] In this embodiment, MgBr2·6H2O is replaced with CaBr2·2H2O; 1-ethyl-2,3-dimethylimidazolium bromide is replaced with tetraphenylphosphine bromide. The remaining processes are the same as in Example 1.

[0048] Example 5

[0049] In this embodiment, MgBr2·6H2O is replaced with SrBr2·6H2O; 1-ethyl-2,3-dimethylimidazolium bromide is replaced with 1-butyl-1-methylpiperidinium bromide. The remaining processes are the same as in Example 1.

[0050] Example 6

[0051] In this embodiment, MgBr2·6H2O is replaced with BaBr2·2H2O; 1-ethyl-2,3-dimethylimidazolium bromide is replaced with 1-butyl-1-methylpiperidinium bromide. The remaining processes are the same as in Example 1.

[0052] Comparative Example 1

[0053] Cs3MnBr5 was synthesized by evaporation crystallization. Cesium bromide and manganese bromide raw materials were dissolved in deionized water, reacted by microwave heating, evaporated and crystallized, and then dried and ball-milled to obtain halide luminescent materials.

[0054] Examples 1-6 all yielded AB-site co-doped manganese ion halide nanomaterials with good luminescence properties.

[0055] The materials synthesized in Examples 1-3 were subjected to XRD analysis, and the results are as follows: Figure 2 This demonstrates that the halide nanomaterials synthesized by the method of the present invention have high phase purity and low impurity content.

[0056] like Figure 3 These are the absorption spectra and bandgap spectra of the materials obtained in Examples 1-3. They show that the materials have high light absorption capacity.

[0057] like Figure 4 The results of PL spectrum analysis of the materials synthesized in Examples 1-3 and Comparative Example 1 show that the luminescence performance of the materials synthesized in this invention is significantly improved.

[0058] Figure 5 The image shows a photograph of the material synthesized in Example 1, demonstrating its excellent luminescent properties.

Claims

1. A method for synthesizing AB-site co-doped manganese ion halide nanomaterials, characterized in that, Includes the following steps: 1) Cesium bromide, manganese bromide, and A-site and B-site dopant materials are mixed and then subjected to surface activation treatment using cold arc air plasma jet treatment; followed by high-energy ball milling to obtain a mixture; wherein the A-site dopant material is selected from 1-ethyl-2,3-dimethylimidazolium bromide, tetraphenylphosphine bromide, and 1-butyl-1-methylpiperidinium bromide; and the B-site dopant material is selected from alkaline earth metal bromide materials; 2) The mixture is added to a mixed solution of the reaction solvent and ligands, and the reaction is carried out under ultraviolet light to passivate the ligands and obtain the reactants; 3) The reactants are coated with silica to obtain superparamagnetic particles; 4) The superparamagnetic particles were dried, ball-milled and destatically removed to obtain AB-site co-doped manganese halide nanomaterials.

2. The method for synthesizing AB-site co-doped manganese ion halide nanomaterials according to claim 1, characterized in that: In step 1), the B-site dopant raw materials are selected from MgBr2·6H2O, CaBr2·2H2O, SrBr2·6H2O, and BaBr2·2H2O. The B-site dopant raw materials are first continuously dried in an H2 gas stream using microwaves, and then mixed with the other raw materials.

3. The method for synthesizing AB-site co-doped manganese ion halide nanomaterials according to claim 1, characterized in that: The raw material for the B-site dopant is MgBr2·6H2O, and the raw material for the A-site dopant is 1-ethyl-2,3-dimethylimidazolium bromide.

4. The method for synthesizing AB-site co-doped manganese ion halide nanomaterials according to claim 1, characterized in that: In step 2), the reaction solvent is toluene and the ligand is oleic acid.

5. The method for synthesizing AB-site co-doped manganese ion halide nanomaterials according to claim 1, characterized in that: In step 3), the method of silica encapsulation is to add the reactants to an aqueous cyclohexane system and then introduce TEOS for silica encapsulation.

6. An AB-site co-doped manganese halide nanomaterial prepared by a method for synthesizing AB-site co-doped manganese halide nanomaterials as described in any one of claims 1-5.

7. The AB-site co-doped manganese halide nanomaterial according to claim 6, characterized in that: The molecular formula is xMg:(Cs) 0.85 EMMIM 0.15 )3MnBr5, the value of x is 5%-15%.

8. The AB-site co-doped manganese ion halide nanomaterial according to claim 7, characterized in that: The value of x is 10%.

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