Zero-dimensional structure rare earth-based luminescent material and preparation method and application thereof

Abstract

The invention discloses a zero-dimensional structure rare earth-based luminescent material as well as a preparation method and application thereof, and belongs to the technical field of luminescent materials. The preparation method comprises the following steps: dissolving cyanomethyl triphenylphosphonium chloride and terbium chloride hexahydrate in an ethanol solvent, and carrying out solvothermal reaction to obtain (TbO3Cl3) (TPP) 3; terbium ions (Tb < 3 + >) in the (TbO3Cl3) (TPP) 3 are coordinated with oxygen atoms and chlorine atoms to form a [TbCl3O3] octahedron, the [TbCl3O3] octahedron is connected with organic cations through shared oxygen atoms to form a zero-dimensional structure on the molecular level, the unique structure of the [TbCl3O3] octahedron is beneficial to inhibition of non-radiative energy transfer between Tb < 3 + >, so that the luminous efficiency is remarkably improved, the (TbO3Cl3) (TPP) 3 is applied to a white light LED as green fluorescent powder, and the luminous efficiency is improved. And the color rendering index of the white light LED is as high as 91.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of luminescent materials, and particularly relates to a zero-dimensional structure rare earth-based luminescent material and a preparation method and application thereof. BACKGROUND

[0002] In the past few years, white light emitting diodes (WLEDs) have become one of the most widely used white light sources in the field of solid state lighting (SSL) due to their low energy consumption, high luminous efficiency and other outstanding advantages. However, the rapid development of society has made people's requirements for lighting quality continue to improve, and it is urgent to develop high-quality WLEDs with high color rendering index and environmental friendliness. High color rendering index can accurately restore the true color of objects, and environmental friendliness is in line with the current green development concept, so it is of great significance to prepare high-performance WLEDs.

[0003] In this process, rare earth ions play a key role. The rich energy levels of rare earth ions can produce diverse and stable luminescence. By reasonably introducing rare earth ions, the luminescence spectrum of WLEDs can be precisely controlled, thereby effectively improving the color rendering index of the device. At the same time, some rare earth ion-doped materials can also reduce the use of harmful substances, helping WLEDs to achieve environmental friendliness and promoting the development of the lighting industry to a higher quality. Currently, the rare earth luminescent materials used to manufacture white light LED devices are mainly some rare earth ion-doped oxide fluorescent powders. However, rare earth ion-doped oxide fluorescent powders need to be synthesized by high-temperature solid-phase method, and it is difficult to accurately control the doping concentration and uniformity, and the additional cost caused by the increased process complexity limits its application in white light LEDs. In addition, in terms of color rendering index, although the doping of rare earth ions can improve the luminescent efficiency, the high phonon energy of the oxide matrix easily causes non-radiative transition, thereby reducing the luminescent efficiency of the material.

[0004] In summary, in view of the disadvantages of rare earth-doped oxide fluorescent powders such as harsh synthesis conditions, high production cost and low color rendering index, it is of great significance to explore a new type of rare earth luminescent material system that can be synthesized at low temperature and has a high color rendering index. SUMMARY

[0005] In view of the above prior art, the application discloses a zero-dimensional structure rare earth-based luminescent material and a preparation method and application thereof, so as to solve the problems of the prior art, such as the complex preparation process, high cost, harsh conditions and other factors of rare earth ion-doped luminescent materials, which are not conducive to large-scale production; and solve the technical problem of low color rendering index of the prepared luminescent material.

[0006] In order to achieve the above purpose, the technical scheme adopted by the application is to provide a zero-dimensional structure rare earth-based luminescent material, the chemical formula of the luminescent material is (TbO3Cl3)(TPP)3, the crystal structure of the luminescent material is trigonal system, and the space group is R3, Tb 3+ The ion is coordinated with oxygen atoms and chlorine atoms to form a TbO3Cl3 octahedron, and the cell parameter is: a = 34.4151 Å, b =34.4151 Å, c = 32.4649 Å, α = 90°, β = 91.837°, gamma = 90°, Z = 9.

[0007] The application further discloses a preparation method of the zero-dimensional structure rare earth-based luminescent material, which comprises the following steps: dissolving cyanomethyltriphenylphosphonium chloride and terbium trichloride hexahydrate in a solvent, performing a solvothermal reaction, filtering a reaction solution, and obtaining the product after the solvent in the filtrate is volatilized at room temperature; the solvothermal reaction temperature is 100 DEG C, and the solvothermal reaction time is 5 days.

[0008] Based on the above technical scheme, the application can be further improved as follows: Further, the solvent is ethanol; and the ratio of cyanomethyltriphenylphosphonium chloride, terbium trichloride hexahydrate and the solvent is 1 mmol:0.5 mmol:2 mL.

[0009] The application further discloses application of the zero-dimensional structure rare earth-based luminescent material in preparation of a luminescent device.

[0010] The application has the following beneficial effects: 1. The (TbO3Cl3)(TPP)3 is synthesized by using a low-temperature thermal solvent method, so that the synthesis process is simplified, and energy consumption and production cost are reduced; the (TbO3Cl3)(TPP)3 is an intrinsic luminescent material, terbium ions (Tb 3+ ) are coordinated with oxygen atoms and chlorine atoms to form [TbCl3O3] octahedrons, the [TbCl3O3] octahedrons are connected with organic cations by sharing oxygen atoms to form a zero-dimensional structure at a molecular level; the Tb 3+ is completely isolated by the triphenylphosphonium cations, and the Tb 3+ occupies fixed lattice sites, and this unique structure helps to inhibit non-radiative energy transfer between the Tb 3+ , thereby helping to significantly improve the luminescent efficiency.

[0011] 2. The (TbO3Cl3)(TPP)3 can emit bright green light under ultraviolet light excitation, and the photoluminescence quantum yield is close to 100%. When the (TbO3Cl3)(TPP)3 is applied as a green fluorescent powder in a white light LED, the color rendering index of the white light LED is as high as 91. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 A schematic diagram of the crystal structure of (TbO3Cl3)(TPP)3; Figure 2 The powder X-ray diffraction pattern of (TbO3Cl3)(TPP)3; Figure 3 The infrared spectrum of (TbO3Cl3)(TPP)3; Figure 4 Thermogravimetric analysis curve of (TbO3Cl3)(TPP)3; Figure 5 The excitation-emission spectrum of (TbO3Cl3)(TPP)3; Figure 6 The CIE color coordinates of (TbO3Cl3)(TPP)3; Figure 7 The emission spectra of (TbO3Cl3)(TPP)3 at different excitation wavelengths are shown. Figure 8 This is the electroluminescence spectrum of a white LED device; Figure 9 A photograph of a white LED device; Figure 10 Here are the CIE color coordinates for the white LED device. Detailed Implementation

[0013] The specific embodiments of the present invention will be described in detail below with reference to examples.

[0014] Example 1 A zero-dimensional rare-earth-based luminescent material is prepared by the following steps: Cyanomethyltriphenylphosphine chloride (C 20 H 17 NPCl (0.3377 g, 1 mmol) and terbium trichloride hexahydrate (TbCl3·6H2O, 0.1866 g, 0.5 mmol) were dissolved in 2 mL of ethanol. The above mixed solution was sealed in a polytetrafluoroethylene liner and reacted at 100 °C for 5 days. Then, it was naturally cooled to room temperature, the reaction solution was filtered, and after the solvent in the filtrate evaporated at room temperature, colorless and transparent rod-shaped crystals (TbO3Cl3)(TPP)3 were obtained.

[0015] Test case I. Structural Testing ① Figure 1 This is a schematic diagram of the crystal structure of compound (TbO3Cl3)(TPP)3; compound (TbO3Cl3)(TPP)3 crystallizes in the trigonal crystal system, space group [space group missing]. R 3. Cell parameters a = 34.4151 Å,b = 34.4151 Å, c = 32.4649 Å, α = 90°, β = 91.837°, gamma = 90°, Z = 9. The smallest asymmetric structural unit of (TbO3Cl3)(TPP)3 consists of 1 Tb atom, 3 Cl atoms, 3 P atoms, 3 O atoms, 45 H atoms, and 54 C atoms. Tb coordinates with 3 O atoms and 3 Cl atoms to form a [TbCl3O3] octahedron, in which the [TbCl3O3] octahedron is connected to the organic cation through shared oxygen atoms; as can be seen from the figure, the [TbCl3O3] octahedron is completely isolated by the wide-bandgap triphenylphosphine, thus forming a zero-dimensional structure at the molecular level.

[0016] ② Powder X-ray diffraction analysis was performed on (TbO3Cl3)(TPP)3 prepared in Example 1, and the obtained PXRD pattern is shown below. Figure 2 As shown in the figure, the position of the PXRD diffraction peak of compound (TbO3Cl3)(TPP)3 is consistent with the XRD data fitted by single crystal, indicating that the prepared (TbO3Cl3)(TPP)3 is a pure phase.

[0017] ③ Figure 3 The infrared spectrum of compound (TbO3Cl3)(TPP)3, 3000-2800 cm⁻¹ -1 The nearby absorption peaks are due to the stretching vibrations of the CH bond, 1680-1600 cm⁻¹ -1 The absorption peaks around 1400 cm⁻¹ belong to the stretching vibrations of the C=C bond in organic cations. -1 The absorption peaks around 1100 cm⁻¹ are influenced by the stretching vibration of the PO bond. -1 The nearby absorption peak is due to the stretching vibration of the CP bond, located at 800 cm⁻¹. -1 The absorption peaks around 500 cm⁻¹ are due to the vibration of the Tb-Cl bond. -1 The absorption peak at that point is due to the vibration of the Tb-O bond.

[0018] II. Performance Testing ① Figure 4 This is the thermogravimetric analysis (TbO3Cl3)(TPP)3 chromatogram. As can be seen from the figure, the compound (TbO3Cl3)(TPP)3 begins to decompose at 200℃.

[0019] ②The photoluminescence performance test results of compound (TbO3Cl3)(TPP)3 are as follows: Figures 5 to 7 As shown, from Figure 5It can be seen that the compound presents a wide absorption band in the range of 250-385 nm, corresponding to the Tb 3+ 4f 8 -4f 7 5d 1 transition. Upon 287 nm UV excitation, (TbO3Cl3)(TPP)3presents bright green emission with the strongest emission peak at 548 nm, mainly caused by the Tb 3+ 5D4-7F5transition, and the photoluminescence quantum yield is close to 100%. Figure 6 The CIE color coordinates of the compound are (0.31, 0.64). In addition, the emission spectrum of the compound (TbO3Cl3)(TPP)3was tested under different excitation wavelengths (the excitation range is 250-400 nm, and the excitation wavelength interval is 10 nm), as shown in Figure 7 , the position of the emission peak does not change with the change of the excitation wavelength, indicating that there is only one emission center in the compound.

[0020] ③In order to evaluate the application potential of (TbO3Cl3)(TPP)3in white light LED, the phosphor was mixed with commercial Sr5(PO4)3Cl:Eu 2+ and (Sr, Ca)AlSiN3:Eu 2+ phosphors, and coated on a 365 nm UV chip to encapsulate a white light LED device (as shown in Figure 8 ). The electroluminescence spectrum of the device is shown in Figure 9 , and under the driving current of 20 mA, the color temperature of the device is 5128 K, and the color rendering index Ra is as high as 91, and the CIE color coordinates of the device are (0.34, 0.32) (as shown in Figure 10 ).

[0021] Although the specific embodiments of the present application are described in detail in combination with the embodiments, it should not be understood as limiting the protection scope of the patent. Various modifications and variations made by those skilled in the art within the scope described in the claims are still within the protection scope of the patent.

Claims

1. A zero-dimensional rare-earth-based luminescent material, characterized in that, The zero-dimensional rare-earth-based luminescent material has the chemical formula (TbO3Cl3)(TPP)3; its crystal structure is trigonal, and its space group is [missing information]. R 3, Tb 3+ It coordinates with oxygen and chlorine atoms to form a [TbO3Cl3] octahedron, with the following cell parameters: a = 34.4151 Å, b = 34.4151Å, c = 32.4649 Å, α = 90°, β = 91.837°, γ = 90°, Z = 9.

2. The method for preparing the zero-dimensional rare-earth-based luminescent material according to claim 1, characterized in that, Includes the following steps: Cyanomethyltriphenylphosphine chloride and terbium trichloride hexahydrate were dissolved in a solvent and subjected to a solvothermal reaction. The reaction solution was filtered, and the solvent in the filtrate was evaporated to obtain the final product. The solvothermal reaction temperature was 100℃ and the solvothermal reaction time was 5 days.

3. The method for preparing zero-dimensional rare-earth-based luminescent materials according to claim 2, characterized in that, The solvent is ethanol; the ratio of cyanomethyltriphenylphosphine chloride, terbium trichloride hexahydrate, and the solvent is 1 mmol: 0.5 mmol: 2 mL.

4. The application of the zero-dimensional rare-earth-based luminescent material according to claim 1 in the fabrication of luminescent devices.

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