High-fluorescence quantum efficiency and high-stability molecular sieve confined csPbBr3 quantum dot composite material and preparation method thereof
By encapsulating CsPbBr3 quantum dots inside Mg-doped pure silica zeolite molecular sieves through high-temperature solid-state reaction, the problems of low stability and low fluorescence efficiency of CsPbX3 materials were solved, achieving high fluorescence quantum efficiency and long-term stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NORTHEASTERN UNIV CHINA
- Filing Date
- 2025-03-07
- Publication Date
- 2026-05-29
AI Technical Summary
Existing CsPbX3 luminescent materials have poor stability to oxygen, moisture, heat, and chemicals, which makes them unstable in practical optoelectronic applications and results in low fluorescence quantum efficiency.
CsPbBr3 quantum dots were confined within a Mg-doped pure silica zeolite molecular sieve through in-situ encapsulation via high-temperature solid-state reaction. The collapse of the Mg-doped pure silica zeolite molecular sieve framework at high temperatures reduced lattice defects, improved fluorescence quantum efficiency, and enhanced stability.
The prepared molecular sieve-confined CsPbBr3 quantum dot composite material exhibits high fluorescence quantum efficiency (over 97%) and excellent optical stability, maintaining fluorescence stability in water for over 100 days.
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Figure CN120248878B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of optoelectronic materials technology, specifically to a molecular sieve-confined CsPbBr3 quantum dot composite material with high fluorescence quantum efficiency and high stability, and its preparation method. Background Technology
[0002] CsPbX3 (X = Cl, Br, I) perovskite nanocrystals are an emerging material with high fluorescence quantum efficiency (PLQY), narrow-band emission, and tunable fluorescence wavelengths covering the entire visible region, attracting widespread attention for applications in optoelectronic devices such as laser emitters, displays, light-emitting diodes, and solar cells. However, the poor stability of current CsPbX3 luminescent materials to oxygen, moisture, heat, and chemicals still limits their practical optoelectronic applications. Continuously improving the luminescent efficiency of these materials remains a significant challenge for future practical optoelectronic applications. Several effective methods have been proposed to improve the luminescent efficiency of perovskites, such as surface passivation, surface coating, and metal ion doping. Introducing metal heteroatoms into the target lattice shows great potential in tuning the optical properties of CsPbX3 perovskite materials.
[0003] To date, the hot-injection method has been used to dope perovskite lattices with metal cations of different valence states (Na+, Na ... + Mn 2+ Al 3+ Mg has become an effective method to improve the luminescence efficiency of CsPbX3. Among them, Mg has high abundance, is non-toxic, and environmentally friendly. 2+ The ion exhibits a six-coordinate preference, and the dissociation energy of the Mg-X bond formed with the halide ion (X) is similar to that of the Pb-X bond. Therefore, Mg... 2+ The ion is considered to be Pb in the CsPbX3 lattice. 2+ The best coordination substitute for ions and readily reacts with Br - Ions forming octahedral coordination are ideal cation dopants. However, CsPbX3 quantum dots prepared by this method exhibit high defect density and poor structural stability, making the emission of metal-doped CsPbX3 quantum dots still highly unstable and limiting in practical applications. Therefore, it remains necessary to prepare CsPbX3 quantum dots with stable fluorescence emission and ultra-high PLQY. Summary of the Invention
[0004] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.
[0005] In a first aspect, the present invention provides a molecular sieve-confined CsPbBr3 quantum dot composite material with high fluorescence quantum efficiency and high stability. The molecular sieve-confined CsPbBr3 quantum dot composite material is based on the framework collapse of Mg-doped pure silica zeolite molecular sieve at high temperature, and the CsPbBr3 quantum dots are confined inside the Mg-doped pure silica zeolite molecular sieve through in-situ encapsulation by high-temperature solid-phase reaction.
[0006] Furthermore, the high-temperature solid-state reaction in-situ encapsulation includes: at high temperature, the Mg-doped pure silicon zeolite molecular sieve framework partially collapses, Mg atoms detach from the Mg-doped pure silicon zeolite molecular sieve framework, and the detached Mg atoms participate in the formation of the CsPbBr3 quantum dot lattice under high temperature, replacing part of the Pb. 2+ The ion sites are reduced, and the lattice defects of the CsPbBr3 quantum dots are decreased, so that the fluorescence quantum efficiency of the molecular sieve-confined CsPbBr3 quantum dot composite material reaches more than 97%, and it can maintain fluorescence stability in water for more than 100 days.
[0007] Furthermore, the Mg-doped pure silica zeolite molecular sieve is doped with Mg element in the pure silica zeolite molecular sieve framework by a hydrothermal one-pot method.
[0008] A second aspect of the present invention provides a method for preparing the above-mentioned molecular sieve-confined CsPbBr3 quantum dot composite material with high fluorescence quantum efficiency and high stability, wherein the method for preparing the molecular sieve-confined CsPbBr3 quantum dot composite material includes:
[0009] Preparation of the Mg-doped pure silica zeolite molecular sieve;
[0010] The CsPbBr3 quantum dots were in situ encapsulated inside the Mg-doped pure silica zeolite molecular sieve via a high-temperature solid-phase reaction.
[0011] Furthermore, the Mg-doped pure silica zeolite molecular sieve is prepared by a hydrothermal one-pot method, comprising: mixing a silicon source, deionized water, a magnesium source and a template agent, adjusting the pH value of the reaction system, then hydrothermally crystallizing in a reaction vessel, and finally removing the template agent by heat treatment to obtain the Mg-doped pure silica zeolite molecular sieve.
[0012] Furthermore, the pH of the reaction system is adjusted to 12-13.5. The hydrothermal crystallization is carried out at 160℃-180℃ for 70-80 hours. The removal of the template agent by heat treatment is carried out at 500℃-600℃ for 5-7 hours. The molar ratio of the silicon source to the magnesium source is (5-9.5):1, wherein the silicon source is tetraethyl orthosilicate and the magnesium source is magnesium chloride hexahydrate. The template agent is tetrapropylammonium hydroxide.
[0013] Furthermore, the in-situ encapsulation of the CsPbBr3 quantum dots inside the Mg-doped pure silica zeolite molecular sieve via a high-temperature solid-phase reaction includes: thoroughly mixing CsBr, PbBr2, and the Mg-doped pure silica zeolite molecular sieve, heating to 450℃-650℃, reacting for 20min-40min, and synthesizing the molecular sieve-confined CsPbBr3 quantum dot composite material.
[0014] Furthermore, the mass ratio of the Mg-doped pure silica zeolite molecular sieve to the sum of the masses of CsBr and PbBr2 is 1:(0.33-3).
[0015] Compared with the prior art, the present invention has at least the following beneficial effects:
[0016] This invention provides a molecular sieve-confined CsPbBr3 quantum dot composite material with high fluorescence quantum efficiency and high stability. It employs a high-temperature solid-state reaction and in-situ encapsulation strategy to confine CsPbBr3 quantum dots within a Mg-doped pure silica zeolite molecular sieve, resulting in a molecular sieve-confined CsPbBr3 quantum dot composite material. On one hand, thanks to the collapse of the Mg-doped pure silica zeolite molecular sieve framework at high temperatures, which isolates it from the erosion of oxygen and polar solvents, the prepared molecular sieve-confined CsPbBr3 quantum dot composite material exhibits excellent optical stability. On the other hand, during the high-temperature solid-state reaction, the Mg-doped pure silica zeolite molecular sieve framework partially collapses, allowing Mg particles detached from the molecular sieve framework to enter the lattice of the CsPbBr3 quantum dots. This reduces lattice defects in the quantum dots and significantly improves the fluorescence quantum efficiency of CsPbBr3. Attached Figure Description
[0017] Figure 1a This is the XRD pattern of the Mg-doped Silicalite-1 molecular sieve prepared in Example 1 of this invention;
[0018] Figure 1b These are SEM images of the Mg-doped Silicalite-1 molecular sieve prepared in Example 1 of this invention;
[0019] Figure 2a This is the XRD pattern of the CsPbBr3-Mg-Si-1 composite material prepared in Example 2 of this invention;
[0020] Figure 2b Here is a SEM image of the CsPbBr3-Mg-Si-1 composite material prepared in Example 2 of this invention;
[0021] Figure 3 This is a comparison of the fluorescence intensity of CsPbBr3-Mg-Si-1 composite materials prepared at different calcination temperatures in Example 2 of this invention;
[0022] Figure 4This is a comparison of the fluorescence intensity of molecular sieves with different mass ratios prepared in Example 2 of the present invention and CsPbBr3-Mg-Si-1 composite materials obtained by calcining quantum dot precursors.
[0023] Figure 5a This is the fluorescence spectrum of the CsPbBr3-Mg-Si-1 composite material prepared in Example 2 of this invention;
[0024] Figure 5b The fluorescence quantum efficiency of the CsPbBr3-Mg-Si-1 composite material prepared in Example 2 of this invention;
[0025] Figure 6 The fluorescence intensity change of the CsPbBr3-Mg-Si-1 composite material prepared in Example 2 of this invention after immersion in water;
[0026] Figure 7 This is the fluorescence quantum efficiency of the CsPbBr3-Si-1 composite material prepared in Comparative Example 2 of this invention;
[0027] Figure 8 This is the fluorescence quantum efficiency of the CsPbBr3-Si-1(MgBr2) composite material prepared in Comparative Example 3 of this invention. Detailed Implementation
[0028] To better understand the above technical solutions, the technical solutions of the present invention will be described in detail below through specific embodiments.
[0029] In a first aspect, the present invention provides a molecular sieve-confined CsPbBr3 quantum dot composite material with high fluorescence quantum efficiency and high stability. The molecular sieve-confined CsPbBr3 quantum dot composite material is based on the framework collapse of Mg-doped pure silica zeolite molecular sieve at high temperature, and the CsPbBr3 quantum dots are confined inside the Mg-doped pure silica zeolite molecular sieve through in-situ encapsulation by high-temperature solid-phase reaction.
[0030] In some embodiments, the in-situ encapsulation of the high-temperature solid-state reaction includes: partial collapse of the Mg-doped pure silica zeolite molecular sieve framework at high temperature, with Mg atoms detaching from the framework. The detached Mg atoms then participate in the formation of the CsPbBr3 quantum dot lattice under high temperature, replacing some of the Pb. 2+ By eliminating ion sites and reducing lattice defects in CsPbBr3 quantum dots, the resulting molecular sieve-confined CsPbBr3 quantum dot composite material achieves a fluorescence quantum efficiency of over 97% and maintains fluorescence stability in water for over 100 days.
[0031] In some embodiments, the Mg-doped pure silica zeolite molecular sieve is doped with Mg element in the pure silica zeolite molecular sieve framework by a hydrothermal one-pot method.
[0032] This invention provides a molecular sieve-confined CsPbBr3 quantum dot composite material with high fluorescence quantum efficiency and high stability. First, Mg-doped pure silica zeolite molecular sieves are synthesized via a one-step hydrothermal method. Then, a high-temperature solid-state reaction and in-situ encapsulation strategy are used to confine CsPbBr3 quantum dots within the Mg-doped pure silica zeolite molecular sieve, resulting in the molecular sieve-confined CsPbBr3 quantum dot composite material. On one hand, thanks to the collapse of the Mg-doped pure silica zeolite molecular sieve framework at high temperatures, which isolates it from the erosion of oxygen and polar solvents, the prepared molecular sieve-confined CsPbBr3 quantum dot composite material exhibits excellent optical stability. On the other hand, under high-temperature solid-state reaction, the Mg-doped pure silica zeolite molecular sieve framework partially collapses, allowing Mg detached from the molecular sieve framework to enter the lattice of the CsPbBr3 quantum dots, thus reducing lattice defects and significantly improving the fluorescence quantum efficiency of CsPbBr3.
[0033] A second aspect of this invention provides a method for preparing the above-mentioned molecular sieve-confined CsPbBr3 quantum dot composite material with high fluorescence quantum efficiency and high stability, wherein the method for preparing the molecular sieve-confined CsPbBr3 quantum dot composite material includes:
[0034] Preparation of Mg-doped pure silica zeolite molecular sieves;
[0035] CsPbBr3 quantum dots were in situ encapsulated inside Mg-doped pure silica zeolite molecular sieves via a high-temperature solid-state reaction.
[0036] In some embodiments, Mg-doped pure silica zeolite molecular sieves are prepared by a hydrothermal one-pot method, comprising: mixing a silicon source, deionized water, a magnesium source and a template agent, adjusting the pH value of the reaction system, then hydrothermally crystallizing in a reaction vessel, and finally removing the template agent by heat treatment to obtain Mg-doped pure silica zeolite molecular sieves.
[0037] Specifically, Mg-doped pure silica zeolite molecular sieves are prepared by a simple hydrothermal synthesis method using a one-pot process. This method has the advantages of simple operation, high reaction efficiency, uniform doping, green and environmentally friendly production, and suitability for large-scale production.
[0038] Optionally, the pH of the reaction system can be adjusted to 12-13.5 using sodium hydroxide solution, which is conducive to the complete hydrolysis of the silicon source.
[0039] In some embodiments, hydrothermal crystallization is performed at 160°C-180°C for 70-80 hours; preferably, hydrothermal crystallization is performed at 170°C for 72 hours; the template agent is removed by heat treatment by heating at 500°C-600°C for 5-7 hours; preferably, the template agent is removed by heat treatment by calcination at 550°C for 6 hours.
[0040] Optionally, the template agent is tetrapropylammonium hydroxide.
[0041] In some embodiments, the molar ratio of silicon source to magnesium source is (5-9.5):1. Optionally, the silicon source is tetraethyl orthosilicate and the magnesium source is magnesium chloride hexahydrate. Preferably, the molar ratio of silicon source to magnesium source is 8:1, so that the silicon source and magnesium source can be fully dissolved in water.
[0042] In some embodiments, CsPbBr3 quantum dots are in-situ encapsulated within Mg-doped pure silica zeolite molecular sieves via a high-temperature solid-state reaction. This includes: thoroughly mixing CsBr, PbBr2, and Mg-doped pure silica zeolite molecular sieves, heating to 450℃-650℃, and reacting for 20-40 minutes to synthesize a molecular sieve-confined CsPbBr3 quantum dot composite material. Preferably, CsBr, PbBr2, and Mg-doped pure silica zeolite molecular sieves are thoroughly mixed, heated to 600℃, and reacted for 30 minutes to synthesize the molecular sieve-confined CsPbBr3 quantum dot composite material.
[0043] Understandably, after the high-temperature solid-state reaction is completed, the reaction products are washed with deionized water and ethanol respectively, and finally dried at room temperature to obtain molecular sieve-confined CsPbBr3 quantum dot composite materials.
[0044] Specifically, the preparation process of the molecular sieve-confined CsPbBr3 quantum dot composite material is a high-temperature solid-state reaction. At 450℃-650℃, the framework of the Mg-doped pure silica zeolite molecular sieve collapses, and Mg atoms detach from the molecular sieve framework. These detached Mg atoms participate in the formation of the CsPbBr3 lattice under high temperature and replace some of the Pb atoms. 2+ Ion sites. This reduces lattice defects in the quantum dots, significantly improving the fluorescence quantum efficiency of CsPbBr3 (reaching 97.4%). CsPbBr3 quantum dots encapsulated within Mg-doped pure silica zeolite molecular sieves exhibit extremely high fluorescence stability. Furthermore, this solid-state synthesis strategy can be used for large-scale preparation of molecular sieve-confined CsPbBr3 quantum dot composites with ultra-high fluorescence quantum efficiency.
[0045] Understandably, unlike the previous hot-injection method which dopes metal cations into the perovskite lattice, the high-temperature solid-state reaction does not require the addition of organic ligands such as oleic acid and oleylamine, or organic solvents such as octadecene and n-hexane, thus greatly reducing environmental pollution.
[0046] In some embodiments, the mass ratio of the Mg-doped pure silica zeolite molecular sieve to the sum of the masses of CsBr and PbBr2 is 1:(0.33-3); preferably, the mass ratio of the Mg-doped pure silica zeolite molecular sieve to the sum of the masses of CsBr and PbBr2 is 1:(0.33-1); more preferably, the mass ratio of the Mg-doped pure silica zeolite molecular sieve to the sum of the masses of CsBr and PbBr2 is 1:0.5.
[0047] Specifically, CsBr and PbBr2 react at high temperature to generate CsPbBr3 quantum dots, which are then encapsulated within the pores of a Mg-doped pure silica zeolite molecular sieve. When the mass ratio of the Mg-doped pure silica zeolite molecular sieve to the sum of the mass of the cesium and lead sources is 1:0.5, the generated CsPbBr3 quantum dots can be uniformly distributed within the molecular sieve without agglomeration.
[0048] Example 1: Preparation of Mg-doped pure silica zeolite molecular sieves
[0049] (I) A method for preparing Mg-doped pure silica zeolite molecular sieves, comprising the following steps:
[0050] (1) Under vigorous stirring at 35°C, 3.54 ml of tetraethyl orthosilicate (TEOS, Tianjin Damao, analytical grade), 9.66 ml of H2O, 1.71 mmol of MgCl2·6H2O (Tianjin Damao, analytical grade) and 3.04 ml of tetrapropylammonium hydroxide (TPAOH, Maclean, 25% by mass) were measured in sequence and hydrolyzed in a 50 ml glass beaker for 3 hours.
[0051] (2) Add 5.2 ml of 1 mol / L NaOH solution to the mixed solution in step (1) and continue stirring at room temperature for 6 hours.
[0052] (3) Transfer the mixed solution in the beaker in step (2) to a 50ml high-temperature stainless steel reactor lined with polytetrafluoroethylene, place it in an oven, and react at 170℃ for 3 days. After the reaction is completed, remove it from the oven and cool it to room temperature.
[0053] (4) Transfer the reaction product from step (3) to a centrifuge tube, wash it twice with deionized water and ethanol respectively, and finally dry it in a vacuum drying oven for 10-12 hours to collect a white powder.
[0054] (5) Weigh a portion of the white powder obtained in step (4) and spread it evenly in a ceramic boat. Place the boat in a tube furnace and calcine it at 550°C for 6 hours to remove the template agent in the molecular sieve. The heating rate is 5°C / min and the cooling rate is 10°C / min. After the reaction is completed and cooled to room temperature, remove the ceramic boat and collect the remaining product to obtain Mg-doped pure silica zeolite molecular sieve (Mg-doped Silicalite-1 molecular sieve, labeled as Mg-Si-1).
[0055] (II) Characterization
[0056] The XRD pattern and SEM image of the Mg-doped pure silica zeolite molecular sieve prepared in Example 1 are shown below. Figure 1a and Figure 1b As can be seen from the figure, the hydrothermally prepared Mg-doped pure silica zeolite molecular sieve exhibits a distinct MFI topology and good crystallinity. Electron micrographs show that the prepared Mg-doped pure silica zeolite molecular sieve has uniform size and regular morphology.
[0057] Example 2: Preparation of Mg-doped molecular sieve-confined CsPbBr3 quantum dot composite material
[0058] (I) A method for preparing molecular sieve-confined CsPbBr3 quantum dot composite materials, comprising the following steps:
[0059] (1) Weigh out 0.067-0.6 mmol CsBr (14.3-127.8 mg) and 0.067-0.6 mmol PbBr2 (24.7-220.2 mg) respectively, and grind them evenly in an agate mortar.
[0060] (2) Weigh 116 mg of Mg-doped Silicalite molecular sieve (Mg-Si-1) again and add it to the agate mortar in step (1). After grinding for 5 minutes, spread the mixture evenly in a ceramic boat and then put it into a tube furnace. Calcine it at 450-650℃ for 30 minutes, with a heating rate of 10℃ / min and a cooling rate of 4℃ / min. After the reaction is complete, cool it to room temperature and take it out.
[0061] (3) Pour the powder from the boat in step (2) into a 50ml beaker, add 20ml of deionized water, stir at room temperature for 30 minutes, and finally centrifuge at a speed of 9000 rpm and wash the product twice with deionized water and ethanol respectively.
[0062] (4) The precipitate obtained in step (3) was dried at room temperature for 12 hours and the Mg-doped molecular sieve confined CsPbBr3 quantum dot composite material (labeled as CsPbBr3-Mg-Si-1) was collected.
[0063] (II) Characterization
[0064] Example 2: The XRD patterns and SEM images of the Mg-doped molecular sieve-confined CsPbBr3 quantum dot composite material prepared by calcination at 600℃ and a Mg-Si-1 molecular sieve to perovskite precursor mass ratio of 1:0.5 are shown in the figures. Figure 2a and Figure 2b As can be seen from the figure, the CsPbBr3-Mg-Si-1 composite material obtained by the high-temperature solid-state reaction still retains the topological structure of the molecular sieve, but the crystallinity deteriorates, proving that the framework of the molecular sieve partially collapses at high temperatures. The newly appearing pores in the electron micrograph also confirm this.
[0065] Example 2: Comparison of fluorescence intensity of Mg-doped molecular sieve-confined CsPbBr3 quantum dot composites prepared at different calcination temperatures (see Example 2). Figure 3 As can be seen from the figure, the CsPbBr3-Mg-Si-1 composite material prepared at 600℃ exhibits the highest fluorescence intensity.
[0066] Example 2: Comparison of fluorescence intensity of Mg-doped molecular sieve-confined CsPbBr3 quantum dot composites prepared at different mass ratios (the ratio of the mass of Mg-Si-1 molecular sieve to the sum of the masses of CsBr and PbBr2) is shown in [reference needed]. Figure 4 As can be seen from the figure, the CsPbBr3-Mg-Si-1 composite material prepared when the mass ratio of Mg-Si-1 molecular sieve to perovskite precursor is 1:0.5 exhibits the highest fluorescence intensity.
[0067] Example 2: The fluorescence spectrum and fluorescence quantum efficiency of the Mg-doped molecular sieve-confined CsPbBr3 quantum dot composite material prepared by calcination at 600℃ and a Mg-Si-1 molecular sieve to perovskite precursor mass ratio of 1:0.5 are shown in the figure. Figure 5a and Figure 5b As can be seen from the figure, the CsPbBr3-Mg-Si-1 composite material exhibits bright green emission at 522 nm, with a fluorescence quantum efficiency (PLQY) as high as 97.4%.
[0068] Example 2: The fluorescence intensity change of the Mg-doped molecular sieve-confined CsPbBr3 quantum dot composite material prepared by calcination at 600℃ and a Mg-Si-1 molecular sieve to perovskite precursor mass ratio of 1:0.5 after long-term immersion in water is shown in the figure. Figure 6 As can be seen from the figure, the CsPbBr3-Mg-Si-1 composite material retains 105% of its initial luminescence intensity after being immersed in water for 100 days, demonstrating the excellent stability of the composite material.
[0069] Comparative Example 1: Preparation of Pure Silica Zeolite Molecular Sieves
[0070] (I) A method for preparing pure silica zeolite molecular sieves, comprising the following steps:
[0071] (1) Under vigorous stirring at 35°C, 3.54 ml of tetraethyl orthosilicate (TEOS, Tianjin Damao, analytical grade), 9.66 ml of H2O and 3.04 ml of tetrapropylammonium hydroxide (TPAOH, Maclean, mass concentration 25%) were measured in sequence and hydrolyzed in a 50 ml glass beaker for 3 hours.
[0072] (2) Add 5.2 ml of 1 mol / L NaOH solution to the mixed solution in step (1) and continue stirring at room temperature for 6 hours.
[0073] (3) Transfer the mixed solution in the beaker in step (2) to a 50ml high-temperature stainless steel reactor lined with polytetrafluoroethylene, place it in an oven, and react at 170℃ for 3 days. After the reaction is completed, remove it from the oven and cool it to room temperature.
[0074] (4) Transfer the reaction product from step (3) to a centrifuge tube, wash it twice with deionized water and ethanol respectively, and finally dry it in a vacuum drying oven for 10-12 hours to collect a white powder.
[0075] (5) Weigh a portion of the white powder obtained in step (4) and spread it evenly in a ceramic boat. Place the boat in a tube furnace and calcine it at 550°C for 6 hours to remove the template agent in the molecular sieve. The heating rate is 5°C / min and the cooling rate is 10°C / min. After the reaction is completed and cooled to room temperature, remove the ceramic boat and collect the remaining product to obtain pure silica zeolite molecular sieve (pure Silicalite-1 molecular sieve, labeled as Si-1).
[0076] Comparative Example 2: Preparation of CsPbBr3 quantum dot composite material confined by pure silicon molecular sieve
[0077] (I) A method for preparing CsPbBr3 quantum dot composite materials confined by pure silicon molecular sieves, comprising the following steps:
[0078] (1) Weigh out 0.1 mmol CsBr (21.3 mg) and 0.1 mmol PbBr2 (36.7 mg) respectively, and grind them evenly in an agate mortar.
[0079] (2) Weigh 116mg of pure Silicalite molecular sieve (Si-1) again and add it to the agate mortar in step (1). Grind for 5 minutes and then spread the mixture in a ceramic boat. Then put it into a tube furnace and calcine it at 600℃ for 30 minutes. The heating rate is 10℃ / min and the cooling rate is 4℃ / min. After the reaction is finished, take it out after cooling to room temperature.
[0080] (3) Pour the powder from the boat in step (2) into a 50ml beaker, add 20ml of deionized water, stir at room temperature for 30 minutes, and finally centrifuge at a speed of 9000 rpm and wash the product twice with deionized water and ethanol respectively.
[0081] (4) The precipitate obtained in step (3) was dried at room temperature for 12 hours and the pure silicon molecular sieve confined CsPbBr3 quantum dot composite material (labeled as CsPbBr3-Si-1) was collected.
[0082] (II) Characterization
[0083] The fluorescence quantum efficiency of the pure silicon molecular sieve-confined CsPbBr3 quantum dot composite material prepared in Comparative Example 2 is shown in the figure. Figure 7 As can be seen from the figure, the fluorescence quantum efficiency of the CsPbBr3-Si-1 composite material is 28.1%, which is much lower than the fluorescence quantum efficiency of 97.4% of the CsPbBr3-Mg-Si-1 composite material.
[0084] Comparative Example 3: Preparation of Mg-doped CsPbBr3 quantum dot composite material confined within pure silicon molecular sieves
[0085] (I) A method for preparing Mg-doped CsPbBr3 quantum dot composite materials confined within pure silicon molecular sieves, comprising the following steps:
[0086] (1) Weigh out 0.1 mmol CsBr (21.3 mg), 0.1 mmol PbBr2 (36.7 mg), and 0.02 mmol MgBr2 (3.68 mg) respectively and grind them evenly in an agate mortar.
[0087] (2) Weigh 116mg of pure Silicalite molecular sieve (Si-1) again and add it to the agate mortar in step (1). Grind for 5 minutes and then spread the mixture in a ceramic boat. Then put it into a tube furnace and calcine it at 600℃ for 30 minutes. The heating rate is 10℃ / min and the cooling rate is 4℃ / min. After the reaction is finished, take it out after cooling to room temperature.
[0088] (3) Pour the powder from the boat in step (2) into a 50ml beaker, add 20ml of deionized water, stir at room temperature for 30 minutes, and finally centrifuge at a speed of 9000 rpm and wash the product twice with deionized water and ethanol respectively.
[0089] (4) The precipitate obtained in step (3) was dried at room temperature for 12 hours and the pure silicon molecular sieve confined Mg-doped CsPbBr3 quantum dot composite material (labeled as CsPbBr3-Si-1(MgBr2)) was collected.
[0090] (II) Characterization
[0091] The fluorescence quantum efficiency of the pure silicon molecular sieve-confined Mg-doped CsPbBr3 quantum dot composite material prepared in Comparative Example 3 is shown in [Figure 3]. Figure 8 As can be seen from the figure, the fluorescence quantum efficiency of the CsPbBr3-Si-1(MgBr2) composite material is 32.4%, which is much lower than the fluorescence quantum efficiency of 97.4% of the CsPbBr3-Mg-Si-1 composite material.
[0092] In summary, it can be seen from Example 2, Comparative Example 2 and Comparative Example 3 that the CsPbBr3 quantum dots confined using Mg-doped molecular sieves have the highest fluorescence quantum efficiency.
[0093] It will be readily understood by those skilled in the art that the above-described advantageous methods can be freely combined and superimposed without conflict. The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.
Claims
1. A method for preparing a molecular sieve-confined CsPbBr3 quantum dot composite material with high fluorescence quantum efficiency and high stability, characterized in that, include: Preparation of Mg-doped pure silica zeolite molecular sieves; The Mg-doped pure silica zeolite molecular sieve is prepared by a hydrothermal one-pot method, comprising: mixing a silicon source, deionized water, a magnesium source, and a template agent; adjusting the pH value of the reaction system; then hydrothermally crystallizing in a reaction vessel; and finally removing the template agent by heat treatment to obtain the Mg-doped pure silica zeolite molecular sieve; wherein the hydrothermal crystallization is carried out at 160℃-180℃ for 70h-80h; the template agent is tetrapropylammonium hydroxide, the silicon source is tetraethyl orthosilicate, and the magnesium source is magnesium chloride hexahydrate; The CsPbBr3 quantum dots are in situ encapsulated inside the Mg-doped pure silica zeolite molecular sieve by high-temperature solid-phase reaction, including: fully mixing CsBr, PbBr2 and the Mg-doped pure silica zeolite molecular sieve, heating to 450℃-650℃, reacting for 20min-40min, and synthesizing the molecular sieve-confined CsPbBr3 quantum dot composite material. The molecular sieve-confined CsPbBr3 quantum dot composite material is based on the framework collapse of Mg-doped pure silicon zeolite molecular sieve at high temperature, and the CsPbBr3 quantum dots are confined inside the Mg-doped pure silicon zeolite molecular sieve through high-temperature solid-phase reaction in-situ encapsulation. The high-temperature solid-state reaction in-situ encapsulation includes: at high temperature, the Mg-doped pure silicon zeolite molecular sieve framework partially collapses, Mg atoms detach from the Mg-doped pure silicon zeolite molecular sieve framework, and the detached Mg atoms participate in the formation of the CsPbBr3 quantum dot lattice under high temperature, replacing some of the Pb. 2+ The ion sites are reduced, and the lattice defects of the CsPbBr3 quantum dots are decreased, so that the fluorescence quantum efficiency of the molecular sieve-confined CsPbBr3 quantum dot composite material reaches more than 97%, while maintaining fluorescence stability in water for more than 100 days.
2. The method for preparing the molecular sieve-confined CsPbBr3 quantum dot composite material according to claim 1, characterized in that, The pH value of the reaction system is adjusted to 12-13.
5.
3. The method for preparing the molecular sieve-confined CsPbBr3 quantum dot composite material according to claim 1, characterized in that, The removal of the template agent by heat treatment involves heating at 500℃-600℃ for 5-7 hours.
4. The method for preparing the molecular sieve-confined CsPbBr3 quantum dot composite material according to claim 1, characterized in that, The molar ratio of the silicon source to the magnesium source is (5-9.5):
1.
5. The method for preparing the molecular sieve-confined CsPbBr3 quantum dot composite material according to claim 1, characterized in that, The mass ratio of the Mg-doped pure silica zeolite molecular sieve to the sum of the masses of CsBr and PbBr2 is 1:(0.33-3).
6. A molecular sieve-confined CsPbBr3 quantum dot composite material with high fluorescence quantum efficiency and high stability, characterized in that, It is prepared by the preparation method described in any one of claims 1-5.