Far-red luminescent material, preparation method thereof and luminescent device

Abstract

The invention relates to the technical field of solid-state lighting, and particularly discloses a far-red light-emitting material, a preparation method thereof and a light-emitting device. The general chemical formula of the luminescent material is A (2-m) / 3BmC0. 5W0. 5O3: xMn < 4 + >, and A is one or a combination of La, Gd, Lu, Sc and Y rare earth ions; b is one or a combination of Li, Na, K, Rb and Cs alkaline earth metals; c is one or a combination of Mg, Ca, Sr and Ba alkaline earth metals; 0 < = m < = 2; 0.01 mol% < = x < = 50 mol%. The powder material is prepared by adopting a high-temperature solid-phase method, and the method is simple in process, environment-friendly and low in cost. The light-emitting material can emit far-red light, and the technical problems that an existing far-red light-emitting material is few in matrix and poor in performance are effectively solved.

Description

Technical Field

[0001] The present invention relates to the field of solid-state lighting technology, and in particular to a luminescent material that emits far-red light under near-ultraviolet or blue light chip excitation, a preparation method thereof, and a luminescent device containing the luminescent material. Background Art

[0002] Far-red is a type of visible light between red light and near-infrared light. Far-red light is an important light source in plant lighting. An important pigment protein for plant growth is called phytochrome. There are two main types of phytochrome in plants: one is Pfr, which mainly absorbs far-red light with a peak wavelength of 730nm; the other is Pr, which mainly absorbs red light with a peak wavelength of 660nm. Adjusting the ratio of red light to far-red light in plant lighting can adjust the stem length and flowering cycle of plant growth. The research and development of far-red light is an important supplement to plant lighting sources and has very important economic and social value.

[0003] There are currently two main ways to achieve far-red light emission. The first method is to use far-red light semiconductor chips, but they are expensive and not conducive to large-scale popularization and utilization. The second method is to use near-ultraviolet or blue light chips to excite far-red luminescent materials to achieve far-red light emission. This combined packaging method has many advantages such as high luminous efficiency, simple device structure, and low cost, and has received great attention from scientific researchers. Due to the mature technology and low cost of near-ultraviolet or blue light chips, the development of far-red luminescent materials suitable for excitation by such chips has become a research hotspot in recent years and is also a key core issue in achieving far-red emission. Summary of the invention

[0004] The present invention aims to provide a far-red luminescent material excited by a near-ultraviolet or blue light chip, a preparation method thereof and a luminescent device, aiming to solve the technical problems of the existing far-red luminescent materials having less matrix and poor performance.

[0005] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is as follows:

[0006] In the first aspect, the present invention provides a far-red luminescent material under near-ultraviolet or blue light chip excitation, wherein the far-red luminescent material can be excited by near-ultraviolet or blue light between 250-600nm to emit far-red light, and the main peak of the far-red light is between 680-730nm; the chemical formula of the far-red luminescent material is A (2-m) / 3 B m C 0.5 W 0.5 O3:xMn 4+, wherein 0≤m≤2; 0.01mol%≤x≤50mol%; A is one of the rare earth ions La, Gd, Lu, Sc, and Y or a combination thereof; B is one of the alkaline earth metals Li, Na, K, Rb, and Cs or a combination thereof; C is one of the alkaline earth metals Mg, Ca, Sr, and Ba or a combination thereof; W is tungsten; Mn 4+ It is a tetravalent manganese ion and a luminescent ion.

[0007] According to an embodiment of the present invention, the Mn element may substitute for the lattice position where the W element is located.

[0008] According to the embodiments of the present invention, the luminescent material has high luminescent quantum yield and luminescent stability, and has great application potential in the field of plant lighting.

[0009] According to another aspect of the present application, a method for preparing the above-mentioned far-infrared luminescent material is provided, which has the advantages of simple process and low production cost.

[0010] The preparation method comprises the following steps:

[0011] (1) According to chemical formula A (2-m) / 3 B m C 0.5 W 0.5 O3:xMn 4+ Weigh the compound raw materials of each element and the flux in a stoichiometric ratio, mix and grind thoroughly;

[0012] (2) placing the mixed material obtained in step (1) into a corundum crucible, placing it in a high-temperature furnace, and calcining it in two steps in an air atmosphere, and cooling it to room temperature along with the furnace after sintering;

[0013] (3) The sintered product obtained in step (2) is fully ground, cleaned, and sieved to obtain the target material.

[0014] Preferably, the flux includes one or more of LiF, Li2CO3, NaF, Na2CO3, H3BO3, and NH4F.

[0015] Preferably, the grinding in step (1) is dry grinding or adding grinding medium ethanol or ultrapure water.

[0016] Preferably, the grinding time in step (1) is 20-120 min.

[0017] Preferably, in the two-step calcination in step (2), the first step calcination temperature is 300-900° C., and the holding time is 30-120 min; the second step calcination temperature is 900-1600° C., and the holding time is 2-24 h.

[0018] The present invention also provides a light-emitting device for plant growth lighting, which comprises an excitation light source and a far-red light-emitting material excited by the excitation light source, wherein the far-red light-emitting material is the far-red light-emitting material described above, and the wavelength range of the excitation light source is from near ultraviolet light to blue light, and optionally, the range from near ultraviolet light to blue light is 250-600nm.

[0019] According to an embodiment of the present invention, the light emitted by the light emitting device has a spectrum that matches well with that required for plant lighting and has a high quantum yield.

[0020] In summary, compared with the prior art, the advantages of the present invention are:

[0021] (1) The far-infrared luminescent material proposed in the present invention has good luminescence performance and high quantum efficiency.

[0022] (2) The far-red luminescent material proposed in the present invention has a wide excitation range and can be excited by both near-ultraviolet light and blue light.

[0023] (3) The method for manufacturing the far-infrared luminescent material proposed in the present invention is feasible, the production process is simple, and it is convenient for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the XRD spectrum of the luminescent material prepared in Example 1.

[0025] Figure 2 This is the excitation spectrum of the luminescent material prepared in Example 1.

[0026] Figure 3 This is the emission spectrum of the luminescent material prepared in Example 1.

[0027] Figure 4 This is the XRD spectrum of the luminescent material prepared in Example 2.

[0028] Figure 5 This is the excitation spectrum of the luminescent material prepared in Example 2.

[0029] Figure 6 This is the emission spectrum of the luminescent material prepared in Example 2.

[0030] Figure 7 This is the XRD spectrum of the luminescent material prepared in Example 3.

[0031] Figure 8 This is the excitation spectrum of the luminescent material prepared in Example 3.

[0032] Fig. 9 This is the emission spectrum of the luminescent material prepared in Example 3. Specific implementation plan

[0033] Example 1

[0034] In the chemical formula, A (2-m) / 3 B m C 0.5 W 0.5 O3:xMn 4+ , when A is La element, B is Li element, C is Mg element, and m=0.05, x=0.02.

[0035] That is, the chemical formula of Example 1 is: La 0.65 Li 0.05 Mg 0.5 W 0.5 O3:0.02Mn 4+ .

[0036] According to the stoichiometric ratio, weigh La2O3: 1.3026g, Li2CO3: 0.0227g, (MgCO3)4·Mg(OH)2·5H2O: 0.5974g, WO3: 1.3973g, MnCO3: 0.0141g, plus flux Li2CO3: 0.1000g, a total of 3.4341g. After the above raw materials are fully mixed, dry grind them for 30-40 minutes. The above mixture is loaded into a corundum crucible and moved into a high-temperature furnace. In an air atmosphere, the temperature is raised to 800℃ at a heating rate of 5℃ / min. After keeping warm for 30min, the temperature is continued to rise to 1215℃, kept warm for 6h, and then cooled to room temperature with the furnace; the sintered product is fully ground to obtain a Mn 4+ Doped with far-infrared luminescent materials.

[0037] Example 2

[0038] In the chemical formula, A (2-m) / 3 B m C 0.5 W 0.5 O3:xMn 4+ , when A is La element, B is Li element, C is Mg element, and m=0.11, x=0.02.

[0039] That is, the chemical formula of Example 1 is: La 0.63 Li 0.11 Mg 0.5 W 0.5 O3:0.02Mn 4+ .

[0040] According to the stoichiometric ratio, weigh La2O3: 1.2625g, Li2CO3: 0.0500g, (MgCO3)4·Mg(OH)2·5H2O: 0.5974g, WO3: 1.3973g, MnCO3: 0.0141g, and add flux Li2CO3: 0.1000g, a total of 3.4213g. After the above raw materials are fully mixed, dry grind them for 30-40 minutes. Put the above mixture into a corundum crucible and move it into a high-temperature furnace. In an air atmosphere, heat it to 800℃ at a heating rate of 5℃ / min. After keeping it warm for 30min, continue to heat it to 1215℃, keep it warm for 6h, and then cool it to room temperature with the furnace; grind the obtained sintered product thoroughly to obtain a Mn 4+ Doped with far-infrared luminescent materials.

[0041] Example 3

[0042] In the chemical formula, A (2-m) / 3 B m C 0.5 W 0.5 O3:xMn 4+ , when A is La element, B is Li element, C is Mg element, and m=0.14, x=0.02.

[0043] That is, the chemical formula of Example 1 is: La 0.62 Li 0.14 Mg 0.5 W 0.5 O3:0.02Mn 4+ .

[0044] According to the stoichiometric ratio, weigh La2O3: 1.2424g, Li2CO3: 0.0636g, (MgCO3)4·Mg(OH)2·5H2O: 0.5974g, WO3: 1.3973g, MnCO3: 0.0141g, plus flux Li2CO3: 0.1000g, a total of 3.4149g. After the above raw materials are fully mixed, dry grind them for 30-40 minutes. The above mixture is loaded into a corundum crucible and moved into a high-temperature furnace. In an air atmosphere, the temperature is raised to 800℃ at a heating rate of 5℃ / min. After keeping warm for 30min, the temperature is continued to rise to 1215℃, kept warm for 6h, and then cooled to room temperature with the furnace; the sintered product is fully ground to obtain a Mn 4+ Doped with far-infrared luminescent materials.

[0045] Embodiment 4-10

[0046] The above-mentioned examples 1-3 are detailed examples, and the difference between examples 4-14 is only the different amounts of raw materials, and the ingredients are prepared according to the stoichiometric ratio. The raw materials, amounts, chemical formulas, sintering temperatures and holding times of each compound in examples 4-14 are shown in Table 1 below.

[0047] Table 1

[0048]

[0049]

[0050]

[0051] The phase analysis test of the luminescent material in the embodiment was carried out using an X-ray diffractometer (DMAX 2500PC, Rigaku Corporation, Japan), and the excitation spectrum and emission spectrum of the luminescent material in the embodiment were tested using an FLS980 (Edinburgh Instruments) fluorescence spectrometer.

[0052] The test method for internal quantum yield, external quantum yield and absorption efficiency is as follows: Use FLS980 (Edinburgh Instruments) fluorescence spectrometer equipped with a 450W xenon lamp coupled to an optical integrating sphere, and then use a standard halogen tungsten lamp to calibrate the optical response of the above instrument, and then test and calculate the internal quantum yield, external quantum yield and absorption efficiency of the material.

[0053] Test method for thermal stability (200℃ / 25℃): Place the luminescent material on a heating platform (77-873K, THMS600, Linkam Scientific Instruments), control the temperature of the sample holder through a temperature control program, and use an FLS980 (Edinburgh Instruments) fluorescence spectrometer to collect the emission spectra of the samples at different temperatures (25-200℃). The thermal stability of the material is analyzed and evaluated through the integrated intensity values ​​of the emission spectra at different temperatures.

[0054] The key performance parameters of the embodiment are shown in Table 2.

[0055] Table 2 Performance parameters of the embodiments

[0056] Internal quantum yield Absorption rate External quantum yield <![CDATA[I 100℃ / I 室温 ]]> Example 1 73％ 85％ 63％ 79％ Example 2 71％ 82％ 58％ 73％ Example 3 70％ 82％ 57％ 72％ Example 4 70％ 83％ 58％ 71％ Example 5 71％ 82％ 58％ 70％ Example 6 72％ 81％ 58％ 72％

[0057] Table 2 summarizes the experimentally measured internal quantum yield, absorptivity, external quantum yield and the ratio of light intensity at 100°C to light intensity at room temperature of Examples 1-6. As can be seen from Table 2, the present invention has superior performance parameters and provides data support for the practical application of plant lighting.

[0058] Finally, the following statement is made on the protection scope of the present invention: the above-listed embodiments are only exemplary descriptions of the present invention and are by no means limiting of the embodiments. Therefore, any changes in different forms and methods made by those skilled in the art based on the above description should be within the protection scope of the present invention.

Claims

1. A far-red luminescent material excited by near-ultraviolet or blue light chip, characterized in that: The far-red luminescent material can be excited by near-ultraviolet and blue light between 250-600nm to emit far-red light, and the main peak of the far-red light is between 680-730nm; the chemical formula of the far-red luminescent material is A (2-m) / 3 B m C 0.5 W 0.5 O3:xMn 4+ , wherein 0≤m≤2; 0.01mol%≤x≤50mol%; A is one of the rare earth ions La, Gd, Lu, Sc, and Y or a combination thereof; B is one of the alkaline earth metals Li, Na, K, Rb, and Cs or a combination thereof; C is one of the alkaline earth metals Mg, Ca, Sr, and Ba or a combination thereof; W is tungsten; Mn 4+ It is a tetravalent manganese ion and a luminescent ion.

2. A method for preparing the far-infrared luminescent material according to claim 1, characterized in that: The preparation method comprises the following steps: (1) According to chemical formula A (2-m) / 3 B m C 0.5 W 0.5 O3:xMn 4+ Weigh the compound raw materials of each element and the flux in a stoichiometric ratio, mix and grind thoroughly; (2) placing the mixed material obtained in step (1) into a corundum crucible, placing it in a high-temperature furnace, and calcining it in two steps in an air atmosphere, and cooling it to room temperature along with the furnace after sintering; (3) The sintered product obtained in step (2) is fully ground, cleaned, and sieved to obtain the target material.

3. The preparation method according to claim 2, characterized in that: The flux includes one or more of LiF, Li2CO3, NaF, Na2CO3, H3BO3, and NH4F.

4. The preparation method according to claim 2, characterized in that: The grinding in step (1) is dry grinding or adding grinding medium ethanol or ultrapure water.

5. The preparation method according to claim 2, characterized in that: The grinding time in step (1) is 20-120 min.

6. The preparation method according to claim 2, characterized in that: In the two-step calcination in step (2), the first step calcination temperature is 300-900° C., and the insulation time is 30-120 min; the second step calcination temperature is 900-1600° C., and the insulation time is 2-24 h.

7. A light emitting device for plant growth lighting, characterized in that: It comprises an excitation light source and a far-red luminescent material excited by the excitation light source, wherein the far-red luminescent material is the far-red luminescent material according to claim 1, and the wavelength range of the excitation light source is from near ultraviolet light to blue light.

8. The light emitting device according to claim 7, characterized in that: The near-ultraviolet to blue light range is 250-600nm.

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