Preparation method of pure green light fluorine-doped perovskite quantum dot solution
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANDONG UNIV OF TECH
- Filing Date
- 2026-03-10
- Publication Date
- 2026-06-26
Smart Images
Figure CN121801558B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of luminescent materials technology, specifically relating to a method for preparing a pure green fluorine-doped perovskite quantum dot solution. Background Technology
[0002] Perovskite quantum dots are a novel type of luminescent material with advantages such as high fluorescence quantum efficiency, tunable emission color, and high color purity. They have wide applications in photodetectors, lighting and displays, and solar cells. However, the intrinsic instability of perovskite quantum dots severely restricts their commercial application. Modern display technologies (such as OLED, QLED, and Micro-LED) have extremely high requirements for the color purity, stability, and luminous efficiency of luminescent materials. Green, as a key component of the RGB three primary colors, directly determines the color gamut coverage and energy efficiency of displays through the performance of green luminescent materials (emission wavelength of 525-535nm). FAPbBr3 quantum dots have an intrinsic emission wavelength between 525-535nm, a full width at half maximum (FWHM) of 20-25nm, and a luminous quantum yield (PLQY) exceeding 90%, making them a promising candidate as a core green luminescent material for next-generation display technologies.
[0003] However, the ionic crystal properties of perovskite quantum dots make them susceptible to degradation by external environmental factors (water, light, or heat), leading to fluorescence decay. In fact, besides the instability caused by environmental factors, another crucial but often overlooked problem exists: perovskite quantum dots, especially FAPbBr3 quantum dots, exhibit severe thermal quenching behavior. That is, the fluorescence quantum efficiency of perovskite quantum dots decays rapidly with increasing temperature. Light-emitting devices (such as LEDs) generate a large amount of heat during actual operation, causing their operating temperature to be much higher than the ambient temperature, thus resulting in fluorescence decay of perovskite quantum dots. Clearly, the thermal quenching characteristics of perovskite quantum dots severely affect the luminous efficiency and color rendering index of light-emitting devices.
[0004] Chinese patent CN112480911A discloses a high-fluorescence-efficiency inorganic lead-free perovskite material and its preparation method. The method involves first mixing cesium iodide and silver iodide and then ball-milling them. Next, cuprous iodide, hydroiodic acid, and a microliter of hypophosphoric acid are added and the mixture is heated in a sealed container at 150–200°C. Finally, the mixture is annealed at room temperature and then cooled at -10°C to -35°C for 1–3 hours to obtain high-purity Cs₂AgI₃:Cu crystals with enhanced fluorescence efficiency. These crystals emit bright blue fluorescence under 302nm ultraviolet light excitation and possess advantages such as being lead-free and chromium-free, having high quantum efficiency, and environmental stability. However, this patented preparation process requires high temperature control, has a long preparation time, and consumes a lot of energy. It also requires precise control of the Cu doping amount, which is not conducive to large-scale production. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing a pure green fluorine-doped perovskite quantum dot solution. This method is simple and easy to operate, and the prepared pure green fluorine-doped perovskite quantum dot solution has excellent thermal stability and no obvious thermal quenching behavior.
[0006] The preparation method of the pure green fluorine-doped perovskite quantum dot solution of the present invention includes the following steps:
[0007] (1) Mix formamidinium bromide (FABr) solution, PbBr2 solution, ligand and photocoupler evenly to obtain precursor solution;
[0008] (2) The precursor solution is added to the antisolvent, the reaction is stirred, the reaction is terminated by adding a terminator, the solid is obtained by centrifugation, the solid is mixed with solvent, centrifuged, filtered, and a colloidal solution is obtained.
[0009] (3) Add fluorine dopant to the colloidal solution and react, then react under ultraviolet light, centrifuge to obtain a solid, add solvent to the solid and mix evenly to obtain a pure green light fluorine doped perovskite quantum dot solution.
[0010] In step (1), the FABr solution is prepared by dissolving FABr in N,N-dimethylformamide or dimethyl sulfoxide to obtain the FABr solution; the PbBr2 solution is prepared by dissolving PbBr2 in N,N-dimethylformamide or dimethyl sulfoxide to obtain the PbBr2 solution; the concentration of the FABr solution is 0.5-1 mol / L, and the concentration of the PbBr2 solution is 0.25-0.5 mol / L.
[0011] In step (1), the molar ratio of FABr in the FABr solution to PbBr2 in the PbBr2 solution is 1-2:1; the ligands are oleic acid and amine, wherein the amine is oleylamine or n-octylamine, and the volume ratio of oleic acid to amine is 15-20:1, preferably 20:1.
[0012] In step (1), the photocoupler is dodecyl mercaptan (DDT) and mercaptopropionic acid (MPA), with a volume ratio of dodecyl mercaptan to mercaptopropionic acid of 1:1-3; the volume ratio of FABr solution, ligand and photocoupler is 20-30:29-52.5:1-5.
[0013] In step (2), the antisolvent is chloroform, the volume ratio of the antisolvent to the FABr solution in step (1) is 30-40:1, preferably 32:1, the stirring time is 5-60s, preferably 35s, the stirring temperature is room temperature, and the terminator is acetonitrile.
[0014] In step (2), the solvent is n-octane or toluene, and the volume ratio of the solvent to the FABr solution in step (1) is 40-80:1.
[0015] In step (3), the fluorine dopant consists of a solvent and a solute. The solvent is N,N-dimethylformamide (DMF), and the solute includes at least one of (3,3,3-trifluoropropyl)trimethoxysilane, triphenylmethylfluorosilane, diphenyldifluorosilane, triethylfluorosilane, NH4F, ammonium fluorosilicate, PbF2, ZnF2, monofluoride DF, or binary fluoride YF2. The D element in monofluoride DF includes one of Li, Na, K, Rb, or Cs, and the Y element in binary fluoride YF2 includes one of Mg, Ca, Sr, or Ba. The mass concentration of the fluorine dopant is 0.1-30%, preferably 20%, and the volume ratio of the fluorine dopant to the colloidal solution is 1:20-200.
[0016] In step (3), the solvent is n-octane or toluene, and the volume ratio of the solvent to the colloidal solution is 1:1-5.
[0017] In step (3), the wavelength of ultraviolet light is 200-365nm.
[0018] The reaction time for adding fluorine dopant in step (3) is 30-120 min, and the reaction time under ultraviolet light irradiation is 5-30 min.
[0019] This invention successfully prepared a pure green fluorine-doped perovskite quantum dot (F-FAPbBr3) solution using a photocoupled assisted liquid phase deposition method. This pure green fluorine-doped perovskite quantum dot solution has excellent thermal stability and optical properties. It can be dried into powder, and then the powder can be uniformly mixed with encapsulating adhesive and encapsulated on an LED chip for application in the lighting and display fields.
[0020] This invention first adds a fluorine dopant after generating FAPbBr3 quantum dots, causing the F... - Coordination with lead ions gradually forms a Pb-F layer on the quantum dot surface, achieving initial passivation of surface defects. Subsequently, a reaction is carried out under ultraviolet light irradiation. Ultraviolet light acts as a coupling driving source, stimulating the action of two photocouplers: dodecyl mercaptan and mercaptopropionic acid. The thiol groups of the long-chain dodecyl mercaptan can assist in stabilizing the unfluorinated Pb on the quantum dot surface through coordination. 2+ This reduces the generation of shallow-level defects; and the long chain of dodecyl mercaptan covers the outermost layer of the quantum dot, stabilizing the surface and blocking the intrusion of external macromolecular impurities, while reserving intermolecular gaps to allow F - And small molecules such as mercaptopropionic acid permeate; under ultraviolet light, mercaptopropionic acid carries F due to its short chain structure. - Diffusion inwards through the long-chain interlayer gaps and Pb-F layer of dodecyl mercaptan, penetrating deep into defect sites, F -Due to its small size, mercaptopropionic acid penetrates to different depths into the quantum dot, forming a concentration gradient; in the near-surface region of the quantum dot, the -SH group of mercaptopropionic acid anchors near-surface Pb. 2+ and release F - To the defect site, a gradient passivation layer is formed to protect F. - Passivation sites inhibit the migration of Br ions, thereby increasing the formation energy of perovskite quantum dots and enabling the prepared pure green light fluorine-doped perovskite quantum dot solution to exhibit excellent thermal stability.
[0021] The beneficial effects of this invention are as follows:
[0022] (1) In this invention, fluorine is doped into the perovskite quantum dot system. Without changing the crystal form and optical properties of the perovskite quantum dots, the prepared pure green light fluorine-doped perovskite quantum dot solution has excellent thermal stability and can achieve green light emission in the range of 525-535nm, which has great commercial application potential. The preparation method is simple and easy to operate, the process is stable, and the process flow is highly controllable.
[0023] (2) In the synthesis of FAPbBr3 quantum dots, the long-chain dodecyl mercaptan has large steric hindrance and can form a loose molecular framework to play a role in spatial isolation, thereby avoiding the aggregation of quantum dots. Mercaptopropionic acid fills the gaps in the framework and works with dodecyl mercaptan to form a stable structure of long-chain framework-short-chain filling, achieving efficient passivation of defects on the surface of quantum dots, promoting uniform nucleation of quantum dots and regulating the lattice structure. At the same time, traditional oleic acid ligands are mainly coordinated with the surface of quantum dots by weak carboxyl-lead, and the adsorption process is completely dynamic and reversible. However, dodecyl mercaptan and mercaptopropionic acid can form an interpenetrating entangled ligand network with the long chain of oleic acid, and the adsorption process is completely dynamic and reversible through the mercapto group and Pb. 2+ The strong sulfur-lead coordination bonds formed firmly fix the entire ligand network on the quantum dot surface, preventing the long oleic acid chains from swelling and falling off by the solvent, greatly enhancing the binding stability between the ligands and the perovskite quantum dot surface, and effectively preventing the aggregation of FAPbBr3 quantum dots.
[0024] (3) This invention employs a photocoupled assisted liquid phase deposition method. The photocoupler and fluoride ions work synergistically to enhance the binding stability of the ligands to the surface of perovskite quantum dots. The fluoride dopant initially forms a surface Pb-F passivation layer. Dodecyl mercaptan fills the unfluorinated defects on the surface, inhibits excessive internal diffusion of fluoride ions, and constructs an outer protective layer. Mercaptopropionic acid carries F - A gradient passivation layer is formed to repair near-surface and internal defects; the three elements work synergistically to form F-Pb coordination on the surface and bulk of perovskite quantum dots, constructing a composite protection system of "surface Pb-F passivation layer-long-chain organic protective layer-gradient passivation layer", which together stabilizes F. - Passivation sites, inhibiting Br -Thermally induced migration and passivation of vacancy defects improve the formation energy of perovskite quantum dots, thereby enhancing the thermal stability of pure green light fluorine-doped perovskite quantum dot solutions and reducing thermal quenching of pure green light fluorine-doped perovskite quantum dot solutions. Attached Figure Description
[0025] Figure 1 This is a TEM image of the pure green light fluorine-doped perovskite quantum dot solution in Example 1.
[0026] Figure 2 The image shows the UV-fluorescence spectrum of the pure green fluorine-doped perovskite quantum dot solution in Example 1.
[0027] Figure 3 These are optical photographs of the pure green fluorine-doped perovskite quantum dot solution in Example 1, where a is an optical photograph of the pure green fluorine-doped perovskite quantum dot solution under normal light, and b is an optical photograph of the pure green fluorine-doped perovskite quantum dot solution under ultraviolet light.
[0028] Figure 4 The image shows the XRD pattern of the pure green light fluorine-doped perovskite quantum dot solution in Example 1.
[0029] Figure 5 The image shows the XRD pattern of the undoped perovskite quantum dot solution in Comparative Example 4.
[0030] Figure 6 The graph shows a comparison of the thermal stability test results of the perovskite quantum dot solutions in Example 1 and Comparative Examples 1-4. Detailed Implementation
[0031] The present invention will be further described below with reference to embodiments.
[0032] Example 1
[0033] (1) Weigh 0.27 g (2.16 mmol) FABr and dissolve it in 3 mL of N,N-dimethylformamide to obtain FABr solution; weigh 0.44 g (1.2 mmol) PbBr2 and dissolve it in 3 mL of N,N-dimethylformamide to obtain PbBr2 solution; mix 250 μL FABr solution, 250 μL PbBr2 solution, 500 μL oleic acid, 25 μL n-octylamine, 10 μL dodecyl mercaptan and 15 μL mercaptopropionic acid evenly to obtain precursor solution;
[0034] (2) The precursor solution obtained in step (1) was injected into 8 mL of chloroform, stirred at room temperature for 35 s, and 3 mL of acetonitrile was added to terminate the reaction. The solid was separated by centrifugation. 15 mL of n-octane was added to the solid and ultrasonically mixed evenly. The mixture was centrifuged and filtered to obtain a colloidal solution containing FAPbBr3 perovskite quantum dots.
[0035] (3) Add 20 μL of (3,3,3-trifluoropropyl)trimethoxysilane solution (solvent is DMF, mass concentration is 20%) to 1 mL of colloidal solution containing FAPbBr3 perovskite quantum dots and react for 30 min. Then react for 10 min under ultraviolet light (wavelength is 200 nm). Centrifuge to obtain solid. Add 1 mL of toluene to the solid and mix well to obtain pure green light fluorine-doped perovskite quantum dot solution.
[0036] TEM image of pure green fluorine-doped perovskite quantum dot solution is shown below. Figure 1 As can be seen from the figure, the fluorine-doped perovskite quantum dots have a uniform size distribution and good morphological uniformity; the UV-fluorescence spectrum of the pure green fluorine-doped perovskite quantum dot solution is shown in the figure. Figure 2 As can be seen from the figure, the emission peak of the pure green fluorine-doped perovskite quantum dot solution is located near 528 nm, with a full width at half maximum (FWHM) of 24 nm. An optical photograph of the pure green fluorine-doped perovskite quantum dot solution is shown below. Figure 3 As can be seen from the figure, the prepared pure green fluorine-doped perovskite quantum dot solution appears green under both normal light and ultraviolet light.
[0037] Example 2
[0038] (1) Weigh 1.5 mmol FABr and dissolve it in 3 mL of dimethyl sulfoxide to obtain FABr solution; weigh 1.5 mmol PbBr2 and dissolve it in 3 mL of dimethyl sulfoxide to obtain PbBr2 solution; mix 300 μL FABr solution, 300 μL PbBr2 solution, 490 μL oleic acid, 25 μL oleylamine, 5 μL dodecyl mercaptan and 5 μL mercaptopropionic acid evenly to obtain precursor solution;
[0039] (2) The precursor solution obtained in step (1) was injected into 12 mL of chloroform, stirred at room temperature for 5 s, and 5 mL of acetonitrile was added to terminate the reaction. The solid was separated by centrifugation. 12 mL of toluene was added to the solid and ultrasonically mixed evenly. The mixture was centrifuged and filtered to obtain a colloidal solution containing FAPbBr3 perovskite quantum dots.
[0040] (3) Add 50 μL of triethylfluorosilane solution (solvent is DMF, mass concentration is 30%) to 1 mL of colloidal solution containing FAPbBr3 perovskite quantum dots and react for 120 min. Then react for 5 min under ultraviolet light (wavelength is 365 nm). Centrifuge to obtain solid. Add 0.5 mL of n-octane to the solid and mix evenly to obtain pure green light fluorine-doped perovskite quantum dot solution.
[0041] Example 3
[0042] (1) Weigh 3 mmol FABr and dissolve it in 3 mL N,N-dimethylformamide to obtain FABr solution; weigh 0.75 mmol PbBr2 and dissolve it in 3 mL N,N-dimethylformamide to obtain PbBr2 solution; mix 400 μL FABr solution, 800 μL PbBr2 solution, 550 μL oleic acid, 35 μL n-octylamine, 25 μL dodecyl mercaptan and 75 μL mercaptopropionic acid evenly to obtain precursor solution;
[0043] (2) The precursor solution obtained in step (1) was injected into 12 mL of chloroform, stirred at room temperature for 60 s, 5 mL of acetonitrile was added to terminate the reaction, centrifuged to obtain a solid, 32 mL of n-octane was added to the solid and ultrasonically mixed evenly, centrifuged, filtered, and a colloidal solution containing FAPbBr3 perovskite quantum dots was obtained.
[0044] (3) Add 50 μL of diphenyl difluorosilane solution (solvent is DMF, mass concentration is 0.1%) to 10 mL of colloidal solution containing FAPbBr3 perovskite quantum dots and react for 90 min. Then react for 30 min under ultraviolet light (wavelength is 300 nm). Centrifuge to obtain solid. Add 2 mL of toluene to the solid and mix evenly to obtain pure green light fluorine-doped perovskite quantum dot solution.
[0045] Comparative Example 1
[0046] Mercaptopropionic acid was replaced with dodecyl mercaptoethanol, and other operations were the same as in Example 1, to obtain a fluorine-doped perovskite quantum dot solution.
[0047] Comparative Example 2
[0048] By replacing dodecyl mercaptopropionic acid with dodecyl mercaptopropionic acid, and performing the other operations as in Example 1, a fluorine-doped perovskite quantum dot solution was obtained.
[0049] Comparative Example 3
[0050] Without adding dodecyl mercaptohydric acid and mercaptopropionic acid, the other operations were the same as in Example 1, resulting in a fluorine-doped perovskite quantum dot solution.
[0051] Comparative Example 4
[0052] Without adding (3,3,3-trifluoropropyl)trimethoxysilane solution (solvent: DMF, mass concentration: 20%), the other operations were the same as in Example 1, resulting in an undoped perovskite quantum dot solution.
[0053] The pure green fluorine-doped perovskite quantum dot solution from Example 1 and the undoped perovskite quantum dot solution from Comparative Example 4 were respectively dropped onto XRD sample slides, dried, and subjected to XRD analysis. The XRD pattern of the pure green fluorine-doped perovskite quantum dot solution from Example 1 is shown below. Figure 4The XRD pattern of the undoped perovskite quantum dot solution in Comparative Example 4 is shown in Figure 4. Figure 5 As can be seen from the figure, compared with the undoped perovskite quantum dot solution, the nanocrystal diffraction peak positions of the pure green fluorine-doped perovskite quantum dot solution in Example 1 did not shift, indicating that fluorine treatment did not change the phase structure of the perovskite quantum dots. - It mainly exists as a surface / interface passivator and does not enter the perovskite phase lattice. As shown in the figure, the peak positions are 14.5°, 20.7°, 29.6°, 33.7°, 37.6°, 42.8°, 44.79°, 47.36°, 52.29°, 54.79° and 57.08° respectively, which belong to the (100), (110), (200), (210), (211), (220), (300), (310), (222), (320) and (321) crystal planes of the cubic phase FAPbBr3 structure.
[0054] The thermal stability of the pure green fluorine-doped perovskite quantum dot solution prepared in Example 1 and the perovskite quantum dot solutions prepared in Comparative Examples 1-4 was tested. The five perovskite quantum dot solutions were heated from 30°C to 100°C, and the fluorescence intensity of the perovskite quantum dot solutions at different temperatures was measured. The test results of the thermal stability of the perovskite quantum dot solutions were obtained. A comparison graph of the thermal stability test results of the perovskite quantum dot solutions is shown below. Figure 6 As can be seen from the figure, when heated to 100℃, the perovskite quantum dot solutions in Comparative Examples 1-4 all exhibited severe thermal quenching behavior, with fluorescence intensity decreasing to 85%, 81%, 80%, and 18% respectively. In contrast, the pure green fluorine-doped perovskite quantum dot solution in Example 1 showed excellent thermal resistance. When heated to 100℃, the fluorescence intensity of the pure green fluorine-doped perovskite quantum dot solution prepared in Example 1 could still maintain 91% of the initial fluorescence value, indicating that the photocoupler and the synergistic doping of F in this invention effectively improved the thermal stability of the perovskite quantum dot solution.
Claims
1. A method for preparing a pure green fluorine-doped perovskite quantum dot solution, characterized in that... Includes the following steps: (1) Mix formamidinium bromide solution, PbBr2 solution, ligand and photocoupler evenly to obtain precursor solution; (2) The precursor solution is added to the antisolvent, stirred and reacted, the reaction is terminated by adding a terminator, centrifuged and separated to obtain a solid, the solid is mixed with solvent, centrifuged and filtered to obtain a colloidal solution containing FAPbBr3 perovskite quantum dots. (3) Add fluorine dopant to colloidal solution and react, then react under ultraviolet light, centrifuge to obtain solid, add solvent to solid and mix evenly to obtain pure green light fluorine doped perovskite quantum dot solution; In step (1), the ligands are oleic acid and amine, wherein the amine is oleylamine or n-octylamine, and the photocoupler is dodecyl mercaptohydric acid and mercaptopropionic acid, wherein the volume ratio of dodecyl mercaptohydric acid to mercaptopropionic acid is 1:1-3. In step (3), the wavelength of ultraviolet light is 200-365nm, and the reaction time under ultraviolet light irradiation is 5-30min.
2. The method for preparing a pure green fluorine-doped perovskite quantum dot solution according to claim 1, characterized in that... In step (1), the formamidinium bromide solution is prepared by dissolving formamidinium bromide in N,N-dimethylformamide or dimethyl sulfoxide to obtain a formamidinium bromide solution; the PbBr2 solution is prepared by dissolving PbBr2 in N,N-dimethylformamide or dimethyl sulfoxide to obtain a PbBr2 solution; the concentration of the formamidinium bromide solution is 0.5-1 mol / L, and the concentration of the PbBr2 solution is 0.25-0.5 mol / L.
3. The method for preparing a pure green fluorine-doped perovskite quantum dot solution according to claim 1, characterized in that... In step (1), the molar ratio of formamidine bromide in the formamidine bromide solution to PbBr2 in the PbBr2 solution is 1-2:1, and the volume ratio of oleic acid to amine is 15-20:
1.
4. The method for preparing a pure green fluorine-doped perovskite quantum dot solution according to claim 1, characterized in that... In step (1), the volume ratio of formamidinium bromide solution, ligand and photocoupler is 20-30:29-52.5:1-5.
5. The method for preparing a pure green fluorine-doped perovskite quantum dot solution according to claim 1, characterized in that... In step (2), the antisolvent is chloroform, the volume ratio of the antisolvent to the formamidine bromide solution in step (1) is 30-40:1, the stirring time is 5-60s, the stirring temperature is room temperature, and the terminator is acetonitrile.
6. The method for preparing a pure green fluorine-doped perovskite quantum dot solution according to claim 1, characterized in that... In step (2), the solvent is n-octane or toluene, and the volume ratio of the solvent to the formamidine bromide solution in step (1) is 40-80:
1.
7. The method for preparing a pure green fluorine-doped perovskite quantum dot solution according to claim 1, characterized in that... In step (3), the fluorine dopant consists of a solvent and a solute. The solvent is N,N-dimethylformamide, and the solute includes at least one of (3,3,3-trifluoropropyl)trimethoxysilane, triphenylmethylfluorosilane, diphenyldifluorosilane, triethylfluorosilane, NH4F, ammonium fluorosilicate, PbF2, ZnF2, monofluoride DF, or binary fluoride YF2. The D element in monofluoride DF includes one of Li, Na, K, Rb, or Cs, and the Y element in binary fluoride YF2 includes one of Mg, Ca, Sr, or Ba. The mass concentration of the fluorine dopant is 0.1-30%, and the volume ratio of the fluorine dopant to the colloidal solution is 1:20-200.
8. The method for preparing a pure green fluorine-doped perovskite quantum dot solution according to claim 1, characterized in that... In step (3), the solvent is n-octane or toluene, and the volume ratio of the solvent to the colloidal solution is 1:1-5.
9. The method for preparing a pure green fluorine-doped perovskite quantum dot solution according to claim 1, characterized in that... The reaction time for adding fluorine dopant in step (3) is 30-120 min.