Ultraviolet-excited blue fluorescent material as well as preparation method and application thereof

Abstract

The invention relates to an ultraviolet-excited blue fluorescent material as well as a preparation method and application thereof, the chemical expression of the blue fluorescent material is Rb2La1-xCl5: xEu < 2 + >, and x is more than or equal to 0.005 and less than or equal to 0.08. The preparation method comprises the following steps: (1) weighing raw material powder of a rubidium source compound, a lanthanum source compound and a europium source compound according to a stoichiometric ratio, and homogenizing to obtain a mixture; (2) grinding and uniformly mixing the mixture obtained in the step (1) to obtain raw material powder; and (3) sintering the ground raw material powder, and then cooling to room temperature to finally obtain the ultraviolet-excited blue fluorescent material. Compared with the prior art, the ultraviolet-excited blue fluorescent material provided by the invention is a novel ultraviolet-excited Eu < 2 + >-doped halide-based blue-light-emitting fluorescent powder, and can meet the urgent demands in the aspects of white-light LEDs (light-emitting diodes), sunlight-like LEDs and full-spectrum LEDs at present.

Description

Technical Field

[0001] The invention relates to the technical field of fluorescent material preparation, and in particular to an ultraviolet excited blue fluorescent material and a preparation method and application thereof. Background Art

[0002] In recent years, with the rapid development of society, people have put forward higher requirements for the LED lighting industry. As the fourth generation lighting source, white LED has become an indispensable light source in contemporary society due to its advantages of low energy consumption, high light conversion efficiency, and environmental friendliness. It has been widely used in modern indoor lighting, plant lighting, special lighting, display equipment, automotive bulbs and other fields. At present, there are two ways to achieve full-spectrum white LED lighting. The first method is to combine InGaN blue light chips with yellow phosphor Y3Al5O 12 :Ce 3+ (YAG:Ce 3+ ) This method has a strong blue light chip peak, and the blue light part is too strong, resulting in uneven luminous intensity, low color rendering index, high color temperature, and certain blue light hazards that are not conducive to physical and mental health. The other is to combine multi-color phosphors on a near-ultraviolet chip to produce white light, which has the advantages of high light conversion efficiency and prevention of blue light hazards. Blue phosphor is one of the most important components of the three-color phosphor, so the synthesis of blue phosphor with strong absorption in the near-ultraviolet region plays an important role in healthy lighting.

[0003] Among the phosphor systems, all-lead-free halides have attracted strong interest due to their comparable optoelectronic properties to perovskite lead halides while being environmentally friendly. So far, several families based on non-toxic elements such as Cu, Bi, Sb, Sn, and Zn have been reported. Due to their superior optoelectronic properties, they have been widely used in solar cells, light-emitting diodes, photodetectors, multiphoton imaging, and other fields. Among the lead-free halides, lanthanum halides have been less studied. Recently, some research results have shown that lanthanum-based compounds may also be a series of lead-free compounds with excellent optoelectronic properties. Summary of the invention

[0004] The purpose of the present invention is to provide a UV-excited blue fluorescent material and its preparation method and application in order to overcome the defects of the above-mentioned prior art. The UV-excited blue fluorescent material provided by the present invention is a new type of UV-excited Eu 2+ Doped halide-based blue light-emitting phosphors can meet the current urgent needs for white light LEDs, sunlight-like LEDs, and full-spectrum LEDs.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] One of the technical solutions of the present invention is to provide a blue fluorescent material excited by ultraviolet light, the chemical expression of which is Rb2La 1-x Cl5:xEu 2+ , where 0.005≤x≤0.08.

[0007] In one embodiment of the present invention, x=0.005, 0.01, 0.02, 0.04, 0.06 or 0.08.

[0008] In one embodiment of the present invention, the ultraviolet excited blue fluorescent material is a new type of ultraviolet excited Eu 2+ Doped halide based 425nm blue light emitting phosphor.

[0009] In one embodiment of the present invention, the ultraviolet excited blue fluorescent material is a powdery material.

[0010] In one embodiment of the present invention, the excitation spectrum range of the ultraviolet excited blue fluorescent material covers 220-400nm, the emission spectrum range of the ultraviolet excited blue fluorescent material covers 400-550nm, and the central emission wavelength of blue light is 425nm.

[0011] In one embodiment of the present invention, the half-peak width of the emission spectrum of the ultraviolet excited blue fluorescent material is in the range of 10 nm to 60 nm.

[0012] The ultraviolet excited blue fluorescent material provided by the present invention is a brand new and unreported ultraviolet excited Eu 2+ The doped halide-based 425nm blue light emitting fluorescent material has a wide excitation band, an effective absorption range covering 200-400nm, can be excited by ultraviolet light, and emits blue light with a central wavelength of 425nm. It has the advantage of stable physical and chemical properties. At the same time, the blue fluorescent material can be prepared by a sealed tube vacuum solid phase reaction method, has the characteristics of simple preparation process and is conducive to industrial production, and can be used as a good candidate material for the wide application of the blue light part of white light LED. The blue fluorescent material can be well matched with the existing ultraviolet chip, meet the needs of the commercial market, and is suitable for applications such as white light LED, sunlight-like LED, and full-spectrum LED.

[0013] The second technical solution of the present invention is to provide a method for preparing an ultraviolet excited blue fluorescent material, comprising the following steps:

[0014] (1) weighing raw material powders of a rubidium source compound, a lanthanum source compound, and a europium source compound according to a stoichiometric ratio, and mixing them uniformly to obtain a mixed material;

[0015] (2) grinding and mixing the mixture obtained in step (1) to obtain a raw material powder;

[0016] (3) Sintering the ground raw material powder and then cooling it to room temperature to finally obtain the ultraviolet excited blue fluorescent material.

[0017] In one embodiment of the present invention, in step (1), according to the chemical formula of the fluorescent material Rb2La 1-x Cl5:xEu 2+ , where 0.005≤x≤0.08, is performed on the basis of the preparation of various raw materials, and then 1wt% to 5wt% of the rubidium source compound is additionally reduced on the basis of the calculated amount of the rubidium source compound, in order to make the phase purer, otherwise there will be a diffraction peak of RbCl.

[0018] In one embodiment of the present invention, in step (1), the rubidium source compound is rubidium chloride (RbCl), the lanthanum source compound is lanthanum chloride (LaCl3), and the europium source compound is europium chloride (EuCl3).

[0019] In one embodiment of the present invention, in step (2), the grinding time of the raw material powder is 5 to 120 minutes.

[0020] In one embodiment of the present invention, in step (3), the sintering conditions are: sintering is carried out in a vacuum atmosphere, the sintering temperature is 500-1000° C., preferably 800-1000° C., and the sintering time is 6-12 hours, preferably 8-10 hours.

[0021] In one embodiment of the present invention, the vacuum atmosphere is obtained by evacuating with a vacuum pump.

[0022] In one embodiment of the present invention, in step (3), the system pressure is maintained at 0 MPa during sintering.

[0023] In one embodiment of the present invention, in step (3), the sintering conditions are as follows: adding the mixed material into a quartz tube, evacuating the quartz glass tube using an oxyhydrogen flame sealing machine and then sealing the tube, placing the tube in a muffle furnace, and then sintering the tube in a vacuum atmosphere.

[0024] A third technical solution of the present invention is to provide an application of an ultraviolet-excited blue fluorescent material, characterized in that the ultraviolet-excited blue fluorescent material is used to prepare an LED chip.

[0025] In one embodiment of the present invention, the LED chip can be applied to the blue light emitting part of a UV chip white light LED, a UV chip solar light LED, a UV chip full spectrum LED or a UV chip high quality white light LED.

[0026] A fourth technical solution of the present invention is to provide an LED chip, wherein the LED chip includes the above-mentioned ultraviolet-excited blue fluorescent material, and the LED chip can be applied to white light LED, sunlight-like LED, and full-spectrum LED.

[0027] Compared with the prior art, the ultraviolet excited blue fluorescent material provided by the present invention is a brand new and unreported ultraviolet excited Eu 2+ The doped halide-based 425nm blue light emitting fluorescent material has the following innovations:

[0028] (1) The blue fluorescent material of the present invention has a wide excitation band, and the effective absorption range covers 200 to 400 nm, and can be excited by ultraviolet light. The obtained blue fluorescent material can emit blue light with a central wavelength of 425 nm under the excitation of 330 nm ultraviolet light, and this has not been reported before.

[0029] (2) The present invention is Eu 2+ The doped blue light emitting fluorescent material has the advantage of stable physical and chemical properties. At the same time, the blue fluorescent material can be prepared by a solid phase reaction method, which has the characteristics of simple preparation process and is conducive to industrial production. It can be used as a good candidate material for the wide application of white light LEDs, solar-like LEDs, and full-spectrum LEDs, and has broad application prospects.

[0030] (3) The blue light emitting fluorescent material of the present invention has an emission wavelength of 400 to 550 nm, can effectively absorb light in the wavelength range of 200 to 400 nm, can be well matched with existing commercial near-ultraviolet LED chips, and is suitable for applications such as ultraviolet chip white light LEDs, ultraviolet chip solar LEDs, ultraviolet chip full-spectrum LEDs, and ultraviolet chip high-quality white light LEDs.

[0031] (4) Currently, commercial white light LEDs are mainly produced by coating yellow Ce on blue LED chips (440-470nm). 3+ Doped yttrium aluminum garnet (YAG:Ce 3+ ) phosphor to produce. However, due to the lack of sufficient red spectrum components, the cold white light produced by this method has the problems of high color temperature (CCT) and low color rendering index (CRI). Therefore, the halide-based blue light emitting fluorescent material of the present invention is a blue emitting phosphor in the three primary colors, which is one of the important components and can be used in white light LEDs. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The photoexcitation spectra of the ultraviolet excited blue fluorescent materials prepared in Examples 1 to 3 of the present invention;

[0033] Figure 2The photoemission spectra of the ultraviolet excited blue fluorescent materials prepared in Examples 1 to 3 of the present invention;

[0034] Figure 3 The XRD diffraction patterns of the blue fluorescent materials prepared in Examples 1 to 3 of the present invention are shown. DETAILED DESCRIPTION

[0035] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments. Based on the given embodiments, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0036] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art.

[0037] Implementation Case 1

[0038] This embodiment provides a method for preparing an ultraviolet-excited blue fluorescent material, the steps of which are as follows:

[0039] 1. Weigh 1 g of RbCl, LaCl3, and EuCl3 raw material powders according to the stoichiometric ratio, and then add 3 wt% of RbCl to make the mass ratio of each raw material RbCl:LaCl3:EuCl3=0.4815:0.5099:0.0027.

[0040] 2. Grind the above raw material mixture in an agate mortar in a glove box for 30 to 60 minutes. After the materials are evenly mixed, load the mixture into a quartz tube, evacuate the quartz glass tube using an oxyhydrogen flame sealing machine, seal it, place it in a muffle furnace, calcine it at 800°C for 10 hours, and then cool it to room temperature to obtain the target product.

[0041] 3. Use fluorescence spectrometer (HITACHIF-7000) to test the spectral properties of the fluorescent material of the system, such as Figure 1 As shown. The results show that the blue fluorescent material of this system has a wide excitation band with a peak value near 330nm and a high spectral peak, which can match well with the commercial ultraviolet light chip. Under the excitation of 330nm ultraviolet light source, the fluorescent material emits bright blue light, and the emission spectrum consists of a narrow emission band (400-550nm) with a peak value at 425nm, as shown in Figure 2. Figure 2 shown.

[0042] 4. X-ray diffraction (Ultima IV-185) was used to test the crystal structure of the blue fluorescent material prepared above. Cu-Kα was used as the target material, and the scanning angle 2θ range was 10-70°. The XRD ray diffraction pattern was as follows: Figure 3 As shown, from Figure 3 It can be seen that the fluorescent material is consistent with the standard card (PDF#04-010-0086), indicating that Eu 3+ The doping of ions does not bring obvious influence on the crystal structure, and the obtained fluorescent material is a pure phase substance isostructural with Rb2LaCl5.

[0043] 5. Using the fluorescence emission spectrum data of the sample, the color coordinates of the sample (0.166, 0.098) were calculated and plotted in the color coordinates. The results showed that the emission of the fluorescent material is in the blue light region and can be used as a good blue light phosphor suitable for white light LEDs.

[0044] The ultraviolet excited Eu obtained in this example 2+ The general formula of the doped blue fluorescent material is Rb2La 1-x Cl5:xEu 2+ , x is 0.005, that is, Rb2La 0.995 Cl5:0.005Eu 2+ .

[0045] Implementation Case 2

[0046] This embodiment provides a method for preparing an ultraviolet-excited blue fluorescent material, the steps of which are as follows:

[0047] 1. Weigh 1 g of RbCl, LaCl3, and EuCl3 raw material powders according to the stoichiometric ratio, and then add 3 wt% of RbCl to make the mass ratio of each raw material RbCl:LaCl3:EuCl3=0.4815:0.4983:0.0053.

[0048] 2. The raw material mixture was placed in an agate mortar in a glove box and ground for 30 to 60 minutes. After the materials were evenly mixed, the mixture was loaded into a quartz tube, the quartz glass tube was evacuated and sealed using a hydrogen-oxygen flame sealing machine, and placed in a muffle furnace for calcination at 850° C. for 10 hours, and then cooled to room temperature to obtain the target product. The photoluminescence performance of the luminescent material is similar to that in Example 1.

[0049] The ultraviolet excited Eu obtained in this example 2+ The general formula of doped blue fluorescent material is Rb2La 1-x Cl5:xEu 2+ , x is 0.01, that is, Rb2La 0.99 Cl5:0.01Eu 2+ .

[0050] Implementation Case 3

[0051] This embodiment provides a method for preparing an ultraviolet-excited blue fluorescent material, the steps of which are as follows:

[0052] 1. Weigh 1 g of RbCl, LaCl3, and EuCl3 raw material powders according to the stoichiometric ratio, and then add 3 wt% of RbCl to make the mass ratio of each raw material RbCl:LaCl3:EuCl3=0.4813:0.4932:0.0106.

[0053] 2. The raw material mixture was placed in an agate mortar in a glove box and ground for 30 to 60 minutes. After the materials were evenly mixed, the mixture was loaded into a quartz tube, the quartz glass tube was evacuated and sealed using a hydrogen-oxygen flame sealing machine, and placed in a muffle furnace for calcination at 900° C. for 10 hours, and then cooled to room temperature to obtain the target product. The photoluminescence performance of the luminescent material is similar to that in Example 1.

[0054] The ultraviolet excited Eu obtained in this example 2+ The general formula of doped blue fluorescent material is Rb2La 1-x Cl5:xEu 2+ , x is 0.02, that is, Rb2La 0.98 Cl5:0.02Eu 2+ .

[0055] Implementation Case 4

[0056] This embodiment provides a method for preparing an ultraviolet-excited blue fluorescent material, the steps of which are as follows:

[0057] 1. Weigh 1 g of RbCl, LaCl3, and EuCl3 raw material powders according to the stoichiometric ratio, and then add 3 wt% of RbCl to make the mass ratio of each raw material RbCl:LaCl3:EuCl3=0.4811:0.4829:0.212.

[0058] 2. The raw material mixture was placed in an agate mortar in a glove box and ground for 30 to 60 minutes. After the materials were evenly mixed, the mixture was loaded into a quartz tube, the quartz glass tube was evacuated and sealed using a hydrogen-oxygen flame sealing machine, and placed in a muffle furnace for calcination at 900° C. for 6 hours, and then cooled to room temperature to obtain the target product. The photoluminescence performance of the luminescent material is similar to that in Example 1.

[0059] The ultraviolet excited Eu obtained in this example 2+ The general formula of doped blue fluorescent material is Rb2La 1-x Cl5:xEu 2+ , x is 0.04, that is, Rb2La0.96 Cl5:0.04Eu 2+ .

[0060] Implementation Case 5

[0061] This embodiment provides a method for preparing an ultraviolet-excited blue fluorescent material, the steps of which are as follows:

[0062] 1. Weigh 1 g of RbCl, LaCl3, and EuCl3 raw material powders according to the stoichiometric ratio, and then reduce 3 wt% of RbCl to make the mass ratio of each raw material RbCl:LaCl3:EuCl3=0.4808:0.4725:0.0318.

[0063] 2. The raw material mixture was placed in an agate mortar in a glove box and ground for 30 to 60 minutes. After the materials were evenly mixed, the mixture was loaded into a quartz tube, the quartz glass tube was evacuated and sealed using a hydrogen-oxygen flame sealing machine, and placed in a muffle furnace for calcination at 900° C. for 8 hours, and then cooled to room temperature to obtain the target product. The photoluminescence performance of the luminescent material is similar to that in Example 1.

[0064] The ultraviolet excited Eu obtained in this example 2+ The general formula of doped blue fluorescent material is Rb2La 1-x Cl5:xEu 2+ , x is 0.06, that is, Rb2La 0.94 Cl5:0.06Eu 2+ .

[0065] Implementation Case 6

[0066] This embodiment provides a method for preparing an ultraviolet-excited blue fluorescent material, the steps of which are as follows:

[0067] 1. Weigh 1 g of RbCl, LaCl3, and EuCl3 raw material powders according to the stoichiometric ratio, and then add 3 wt% of RbCl to make the mass ratio of each raw material RbCl:LaCl3:EuCl3=0.4806:0.4622:0.0423.

[0068] 2. The raw material mixture was placed in an agate mortar in a glove box and ground for 30 to 60 minutes. After the materials were evenly mixed, the mixture was loaded into a quartz tube, the quartz glass tube was evacuated and sealed using a hydrogen-oxygen flame sealing machine, and placed in a muffle furnace for calcination at 900° C. for 8 hours, and then cooled to room temperature to obtain the target product. The photoluminescence performance of the luminescent material is similar to that in Example 1.

[0069] The ultraviolet excited Eu obtained in this example 2+ The general formula of doped blue fluorescent material is Rb2La 1-x Cl5:xEu2+ , x is 0.08, that is, Rb2La 0.92 Cl5:0.08Eu 2+ .

[0070] The preparation parameter processes of implementation cases 1 to 6 are shown in Table 1 below.

[0071] Table 1 Preparation parameters of implementation cases 1 to 6

[0072]

[0073] From Table 1, we can see that Eu 2+ The halide-based blue fluorescent material obtained by doping can emit cyan light with a spectral range of 400-550nm and a central wavelength of 425nm under ultraviolet excitation. It has a strong emission intensity. Under the excitation of a 330nm ultraviolet light source, the phosphor emits bright blue light with stable physical and chemical properties.

[0074] Comparative Example 1

[0075] According to the stoichiometric ratio, 1 g of RbCl and LaCl3 raw material powders were weighed, and an additional 3 wt% of RbCl was added, so that the mass ratio of each raw material was RbCl:LaCl3:EuCl3=0.4808:0.5043.

[0076] The raw material mixture is placed in an agate mortar in a glove box and ground for 30 to 60 minutes. After the materials are evenly mixed, the mixture is loaded into a quartz tube, and the quartz glass tube is evacuated and sealed using an oxyhydrogen flame sealing machine, placed in a muffle furnace, calcined at 900°C for 8 hours, and then cooled to room temperature to obtain the target product. The target product obtained does not emit light.

[0077] Although the present invention has been described in detail above by means of general description, specific implementation methods and tests, it is obvious to those skilled in the art that some modifications or improvements may be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A UV-excited blue fluorescent material, characterized in that: The chemical expression of the blue fluorescent material is Rb2La 1-x Cl5:xEu 2+ , where 0.005≤x≤0.

08.

2. The ultraviolet excited blue fluorescent material according to claim 1, characterized in that: x=0.005, 0.01, 0.02, 0.04, 0.06 or 0.

08.

3. The ultraviolet excited blue fluorescent material according to claim 1, characterized in that: The ultraviolet excited blue fluorescent material is a powdery material.

4. The ultraviolet excited blue fluorescent material according to claim 1, characterized in that: The excitation spectrum range of the ultraviolet excited blue fluorescent material covers 220-400nm, the emission spectrum range of the ultraviolet excited blue fluorescent material covers 400-550nm, and the central emission wavelength of blue light is 425nm.

5. The ultraviolet excited blue fluorescent material according to claim 1, characterized in that: The half-peak width of the emission spectrum of the ultraviolet-excited blue fluorescent material is in the range of 10 nm to 60 nm.

6. The method for preparing a UV-excited blue fluorescent material according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) weighing raw material powders of a rubidium source compound, a lanthanum source compound, and a europium source compound according to a stoichiometric ratio, and mixing them uniformly to obtain a mixed material; (2) grinding and mixing the mixture obtained in step (1) to obtain a raw material powder; (3) Sintering the ground raw material powder and then cooling it to room temperature to finally obtain the ultraviolet excited blue fluorescent material.

7. The method for preparing a UV-excited blue fluorescent material according to claim 6, characterized in that: In step (1), according to the chemical formula of the fluorescent material Rb2La 1-x Cl5:xEu 2+ , wherein 0.005≤x≤0.08, on the basis of preparing various raw materials, further reducing 1wt% to 5wt% of the rubidium source compound on the basis of the calculated amount of the rubidium source compound; In step (1), the rubidium source compound is RbCl, the lanthanum source compound is LaCl3, and the europium source compound is EuCl3.

8. The method for preparing a UV-excited blue fluorescent material according to claim 6, characterized in that: In step (3), the sintering conditions are: sintering in a vacuum atmosphere, a sintering temperature of 500 to 1000° C., and a sintering time of 6 to 12 hours.

9. The use of an ultraviolet excited blue fluorescent material as claimed in any one of claims 1 to 5, characterized in that: The ultraviolet excited blue fluorescent material is used for preparing LED chips.

10. An LED chip, characterized in that: The LED chip comprises an ultraviolet-excited blue fluorescent material as described in any one of claims 1 to 5.

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