CN107974252B

CN107974252B - A nitride light-emitting material and a light-emitting device comprising the same

Info

Publication number: CN107974252B
Application number: CN201711106664.6A
Authority: CN
Inventors: 刘荣辉; 薛原; 刘元红; 张霞; 高慰
Original assignee: Grirem Advanced Materials Co Ltd; Guoke Re Advanced Materials Co Ltd
Current assignee: Youyan Rare Earth High Technology Co Ltd; Grirem Advanced Materials Co Ltd
Priority date: 2017-11-10
Filing date: 2017-11-10
Publication date: 2021-02-26
Anticipated expiration: 2037-11-10
Also published as: CN107974252A

Abstract

A nitride light-emitting material and a light-emitting device comprising the same. The luminescent material comprises an inorganic compound whose chemical formula is M _m A _b X _y D _z , wherein M is one or a combination of two or more of La, Lu, Gd and Y, and A is one or both of Si and Ge Species, X is N, or N and F, D is one or more of Dy, Ce, Pr, which must contain Pr and/or Dy, and 2≤m≤4, 5≤b≤7, 10.5 ≤y≤11.5, 0<z≤0.5. The nitride luminescent material of the present invention can be effectively excited by light in the wavelength range of 350-500 nm and emits efficiently in the visible light region, and is an ideal luminescent material.

Description

Nitride luminescent material and luminescent device comprising same

Technical Field

The invention belongs to the field of luminescent materials, and particularly relates to a nitride luminescent material and a luminescent device comprising the same.

Background

Light Emitting Diodes (LEDs) have the advantages of low voltage, high light efficiency, low energy consumption, long life, no pollution, etc., and have been successfully applied in the fields of semiconductor illumination and liquid crystal flat panel display. In recent years, new single matrix white LEDs have attracted considerable attention. The current white light LED implementations are mainly divided into two types: the first is a combination of three primary color (red, blue, green) LED chips; another is to use LEDs to excite the phosphor mixture to form white light, i.e., white light is formed by the combination of different colors of light emitted by doping different activator ions on a single substrate. Multiple activator ions are easy to have mutual absorption to cause the reduction of luminous efficiency, and Dy is singly doped³⁺Can emit blue-green light respectively after being excitedAnd yellow-orange light, which combine to form white light to avoid the above problems. In addition, doped with Pr³⁺Light emitted by blue light excitation after ionization can also be applied to backlight display to improve color gamut.

In 2008, a novel nitride luminescent material Ce is disclosed by the Japanese institute of Material and Mitsubishi chemistry_xM^III _3-xM^IV _yX^-III _z(JP 2008088362A, JP 2010070773A). The nitride can be excited by light of about 300-530 nm to obtain yellow light, has high thermal stability, can be excited by ultraviolet light of 300-450 nm, and is a novel luminescent material with wide application prospect.

In addition, Dillip. G.R et al reported doping of borates with Dy³⁺The process of ion fabrication of white light emitting materials (dilip. g.r, ramesh. b, reddy. c.m, mallikarjuna. k, ravi. o,&Dhoble.S.J,et al.X-ray analysis and optical studies ofDy³⁺,doped NaSrB₅O₉,microstructures for white light generation.Journal of Alloys&compounds 2014 719-727), while Santa Chawla et al report on aluminates by doping with Pr³⁺The process of ion-obtaining a luminescent material (Chawla, s., Kumar, n.,&Chander,H.Broad yellow orange emission from SrAl₂O₄:Pr³⁺the phosphor with blue excitation for application to white leds, journal of Luminescence,2009: 114-.

Disclosure of Invention

Therefore, an object of the present invention is to provide a nitride light emitting material. The nitride luminescent material can be effectively excited by light with the wavelength range of 350-500nm and efficiently emits in a visible light region, and is an ideal luminescent material.

In order to achieve the purpose, the invention adopts the following technical scheme:

a nitride light emitting material comprising an inorganic compound of the formula [ I ],

M_mA_bX_yD_z [I]

wherein

M is one or the combination of more than two of La, Lu, Gd and Y,

a is one or two of Si and Ge,

x is N, or N and F,

d is one or the combination of more than two of Dy, Ce and Pr, wherein Pr and/or Dy must be contained, and

2. ltoreq. m.ltoreq.4, m being, for example, 2.2, 2.4, 2.5, 2.55, 2.63, 2.7, 2.9, 3.1, 3.3, 3.5, 3.7, 3.85, 3.9, etc.,

b is 5-7, b is, for example, 5.2, 5.4, 5.5, 5.55, 5.63, 5.7, 5.9, 6.1, 6.3, 6.5, 6.7, 6.85, 6.9, etc.,

y is 10.5-11.5, such as 10.6, 10.8, 10.9, 11.0, 11.15, 11.22, 11.3, 11.35, 11.4, 11.45, etc

0 < z.ltoreq.0.5, and z is, for example, 0.02, 0.04, 0.06, 0.08, 0.1, 0.15, 0.2, 0.22, 0.26, 0.32, 0.36, 0.4, 0.42, 0.43, 0.45, 0.48, or the like. Preferably, the luminescent material has a structure similar to La₃Si₆N₁₁The same crystal structure.

Dy singly doped³⁺After being excited, the light emitting diode can respectively emit blue-green light and yellow-orange light, and the combination forms white light, so that the problem of low luminous efficiency caused by the mutual absorption action easily existing among various activator ions is solved. In addition, doped with Pr³⁺Light emitted by blue excitation after ionization can be used for backlight display to improve color gamut. With La₃Si₆N₁₁The crystal structure is used as a substrate, and a luminescent material with high thermal stability can be further prepared, so that the method can be suitable for a device excited by high energy density.

In the nitride luminescent material, the crystal structure is constructed by an M-A polyhedron, and luminescent materials with different structures can be obtained by linking M and A-N tetrahedrons in an angle-angle or edge-edge manner. In order to make the nitride luminescent material of the invention have La₃Si₆N₁₁The nitride luminescent material has the same crystal structure, and other mixed phases are not introduced, so that when the M element is one or the combination of more than two of the trivalent rare earth elements La, Lu, Y and Gd in the nitride luminescent material, the strict growth of the crystal lattice of the luminescent material can be ensured, and the high-stability luminescent material can be obtained. However, the amount of the above elements should be appropriate, and when m < 2, pure phase cannot be generated due to the difference of the element ratio during the firing process, resulting in deterioration of the performance of the light emitting material; when m > 4, the excess of the raw material remains to influence the generation of a pure phase of the luminescent material as well, and the temperature characteristics of the luminescent material are also deteriorated, and therefore, it is necessary to define: m is more than or equal to 2 and less than or equal to 4.

X is N element, which enables the luminescent material synthesized by the selected elements and La₃Si₆N₁₁The same crystal structure. When y is less than 10.5 or y is more than 11.5, the valence in the crystal is unbalanced due to the difference of the element ratio, the instability of the structure is caused, and the ideal luminescent material is not easy to obtain, therefore, the following limitations are required: y is more than or equal to 10.5 and less than or equal to 11.5.

In the nitride luminescent material, D ions are used as activator ions, and after a plurality of experiments, the optimal effect is achieved when the limiting range of the concentration of the activator is more than 0 and less than or equal to 0.5. When the content of D is more than 0.5, on one hand, the structure instability is increased and even a mixed phase is generated due to mismatching of the ion radius after the D enters the crystal lattice, on the other hand, too many D ions generate a concentration quenching effect due to too small ion distance, and the luminous brightness is reduced along with the increase of the D ions.

According to the nitride luminescent material, the peak position of the excitation wavelength and the peak wavelength of the emission wavelength are different according to the selected specific element types and dosage ratios.

Preferably, D is Dy.

Preferably, a is Si.

Preferably, M is La.

Preferably, the peak wavelength of the excitation spectrum of the luminescent material is 380-390 nm, the peak wavelength of the main emission peak is 570-580 nm, and the secondary peak wavelength is 470-480 nm.

Preferably, D is Pr.

Preferably, a is Si.

Preferably, M is La.

Preferably, the peak wavelength of the excitation spectrum of the luminescent material is 450-470 nm, the peak wavelength of the main emission peak is 660-670 nm, and the secondary peak wavelength is 500-510 nm.

Preferably, the luminescent material may be one or a combination of two or more of powder, ceramic, and crystal.

The preparation method of the nitride light emitting material of the present invention can be prepared by methods known in the art, such as a high temperature solid phase method.

In a preferred embodiment of the present invention, the raw materials and their proportions of the elements required in the general formula of the nitride luminescent material according to the present invention are uniformly mixed and then calcined at high temperature; and (3) taking out the furnace after calcining and sintering, and carrying out post-treatment steps including grinding, acid washing, sieving, drying and the like on the powder.

The raw materials of the elements are preferably simple substances or compounds of various metal and nonmetal elements, and the compound is preferably a nitride.

Preferably, the calcination is carried out in a reducing atmosphere or an inert atmosphere, preferably in a high-pressure or atmospheric furnace protected by a reducing atmosphere or an inert atmosphere, in order to ensure a low oxygen content of the environment.

Preferably, the reducing atmosphere or inert atmosphere is one or a combination of two or more of nitrogen, hydrogen or CO gas.

Nitrides, because of their stable covalent bonds, require higher temperatures to facilitate product synthesis. Preferably, according to theory and experiment, the temperature of the high-temperature calcination is 1400-1800 ℃, preferably 1600 ℃, the calcination time is 20min-24h, if the holding time is too short, the reaction is not sufficient, and the excessive time causes abnormal growth of crystal grains, preferably 6-15 h.

It is also an object of the present invention to provide a light-emitting device comprising the luminescent material of the present invention.

Preferably, the light-emitting device further comprises a radiation source. Preferably, the radiation source is a laser light source or a semiconductor light source.

Wherein the laser light source includes but is not limited to vacuum ultraviolet emission source, purple light emission source or blue light emission source; semiconductor light sources include, but are not limited to, ultraviolet LEDs, violet LEDs, blue LEDs, and the like.

Preferably, the light-emitting device further comprises another light-emitting material excited by the radiation source.

Preferably, the other luminescent material is one or a combination of two or more of the following fluorescent substances: (Y, Gd, Lu, Tb)₃(Al,Ga)₅O₁₂:Ce³⁺、β-SiAlON:Eu²⁺、(Ca,Sr)AlSiN₃:Eu²⁺、(Li,Na,K)₂(Ti,Zr,Si,Ge)F₆:Mn⁴⁺、(Ca,Sr,Ba)MgAl₁₀O₁₇:Eu²⁺。

The invention adjusts M: a: the proportion of D can form La taking D ions as luminescent centers₃Si₆N₁₁Crystal structure, which makes the activator center obtain higher transition energy under the action of Si-N tetrahedral field, thereby obtaining high-efficiency emission, and La₃Si₆N₁₁The crystal structure is used as a matrix, so that a luminescent material with high thermal stability is prepared, and the luminescent material can be suitable for a device excited by high energy density.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 shows XRD diffraction peaks and La of the sample obtained in example 1₃Si₆N₁₁Comparing standard cards;

FIG. 2 is La of a sample obtained in example 1_2.9Si₆N₁₁：0.1Dy³⁺Emission spectrum under excitation with 387nm light;

FIG. 3 shows an embodiment15 sample La was obtained_2.91Si₆N₁₁：0.09Pr³⁺Emission spectrum under 460nm light excitation.

Detailed Description

For the purpose of facilitating an understanding of the present invention, the present invention will now be described by way of examples. It should be understood by those skilled in the art that the examples are only for the purpose of facilitating understanding of the present invention and should not be construed as specifically limiting the present invention.

In the following examples, the XRD patterns were subjected to X-ray diffraction using a Co target (λ 1.78892 nm). The emission spectrum is acquired by a high-sensitivity integrated fluorescence spectrometer of FluoroMax-4 model of Horiba company.

Comparative example 1

According to the formula Y_2.9Al₅O₁₁:Dy_0.1The raw materials are weighed according to the mixture ratio. Grinding the raw material mixture in an agate mortar uniformly, putting the mixture into a corundum crucible, roasting the mixture at 1400 ℃ for 4 hours at the heating speed of 5 ℃/min by taking carbon monoxide as a reducing atmosphere, and cooling the mixture to room temperature. And grinding the obtained sintered product, and performing post-treatment processes such as ball milling and grinding to obtain a sample.

Comparative example 2

According to the formula Y_2.91Al₅O₁₁:Pr_0.09The raw materials are weighed according to the mixture ratio. Grinding the raw material mixture in an agate mortar uniformly, putting the mixture into a corundum crucible, roasting the mixture at 1400 ℃ for 4 hours at the heating speed of 5 ℃/min by taking carbon monoxide as a reducing atmosphere, and cooling the mixture to room temperature. And grinding the obtained sintered product, and performing post-treatment processes such as ball milling and grinding to obtain a sample.

The samples prepared in comparative examples 1 and 2 were commercially available YAG phosphors.

Example 1

By mixing the following La_2.9Si₆N₁₁:Dy_0.1LaN, CeN and Si weighed according to stoichiometric ratio₃N₄And mixing the DyN powder in a mortar uniformly, keeping the temperature of 1600 ℃ for 3 hours in a reducing atmosphere, crushing the obtained product, washing with water to remove impurities, sieving and drying to obtain the product.

The XRD pattern of the sample prepared in this example is shown in FIG. 1, demonstrating the formation of La_2.9Si₆N₁₁Phase (1); the emission spectrum under 387nm excitation is shown in fig. 2, demonstrating that a spectrum according to our design is obtained. It was measured that comparative example 1 was selected as a comparison, and the relative luminous intensity of this sample was 145%. When the temperature is raised to 150 ℃, the luminous intensity can still be kept at 87%, which shows the good stability of the product of the invention. The products of examples 2-22 maintained greater than 83% luminous intensity when raised to 150 ℃.

Examples 2 to 14

Examples 2-14 have a similar synthesis to example 1. In examples 2-14, the emission spectra are similar to those of FIG. 2. The chemical formulas of examples 2 to 14 and the relative luminescence intensities thereof are shown in Table 1, and the relative luminescence intensities in Table 1 are compared with those of comparative example 1.

TABLE 1

Name (R)	Chemical composition	Relative luminescence intensity (%)
			Example 2	La₂Dy_0.01Si_6.35N_10.5	110
Example 3	Dy_0.01Gd_2.71Si₅Ge_0.835N_10.5	105
			Example 4	Dy_0.11La_2.89Si₆N₁₁	137
Example 5	Dy_0.066Y_2.1Si₇N_11.5	102
			Example 6	Dy_0.15La₂Si_6.41N_10.7	104
Example 7	Dy_0.07La_2.93Si₆N₁₁	112
			Example 8	Dy_0.386Gd_2.834Si_4.5Ge_1.46N₁₁F_0.5	105
Example 9	Dy_0.07La_2.93Si₆N₁₁	125
			Example 10	Dy_0.06La₄Si₅N_10.5F_0.68	130
Example 11	Dy_0.5Sc_2.33Si_6.5N_11.5	112
			Example 12	Dy_0.04La_3.3Si_5.24N₁₀F_1.02	105
Example 13	Lu₄Dy_0.33Si_4.5Ge_0.5N₁₁	133
			Example 14	Dy_0.05Ce_0.02La_2.93Si₆N₁₁	132

Example 15

By mixing the following La_2.91Si₆N₁₁:Pr_0.09Respectively weighing LaN, CeN and Si in stoichiometric ratio₃N₄And uniformly mixing the PrN powder in a mortar, and carrying out heat preservation for 3 hours at 1600 ℃ in a reducing atmosphere, and crushing, washing and removing impurities, sieving and drying the obtained product to obtain the product.

The emission spectrum of the sample prepared in this example under the excitation of 460nm light is similar to that of FIG. 3. This sample was measured to have a luminous intensity of 150% by comparison with comparative example 2.

Examples 16 to 22

Examples 16-22 have a similar synthesis to example 15. In examples 16 to 22, the emission spectra are shown in FIG. 3. The chemical formulas of examples 16 to 22 and their relative luminous intensities are shown in Table 2, and the relative luminous intensities in Table 2 are compared with those of comparative example 2.

TABLE 2

Name (R)	Chemical composition	Relative luminescence intensity (%)
			Example 16	Pr_0.5Lu₄Ge_5.25N_11.5	145
Example 17	Pr_0.4La_3.93Si₅N₁₁	146
			Example 18	Pr_0.45Lu_2.9Ge₆N₁₀F_1.01	122
Example 19	Lu_0.02Pr_0.07La_3.23Si_5.91N_11.2	112
			Example 20	Y_0.016Pr_0.1Lu_2.05Ge₇N_11.5	148
Example 21	Dy_0.03Ce_0.02Lu_1.45Pr_0.35Gd_2.115Si_5.649N_11.5	115
			Example 22	Dy_0.2Lu_0.8Pr_0.01La_1.2Si_3.13Ge₃N₁₀F_1.15	112

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.

Claims

1. The use of a nitride light emitting material in single activator white light emission or backlight display, characterized in that the light emitting material comprises an inorganic compound of formula [ I ],

M_mA_bX_yD_z [I]

wherein

M is one or the combination of more than two of La, Lu, Gd and Y,

a is one or two of Si and Ge,

x is N, or N and F,

d is Dy or Pr or contains both Ce and Pr

2≤m≤4，

5≤b≤7，

10.5≤y≤11.5，

0＜z≤0.5；

When D is Dy, the peak wavelength of the excitation spectrum of the luminescent material is 380-390 nm, the peak wavelength of the main emission peak is 570-580 nm, the wavelength of the secondary peak is 470-480 nm, and the single activator is used for white light emission;

or when D is Pr or contains Ce and Pr, the peak wavelength of the excitation spectrum of the luminescent material is 450-470 nm, the peak wavelength of the main emission peak is 660-670 nm, the secondary peak wavelength is 500-510 nm, and the application is backlight display.

2. Use according to claim 1, wherein the luminescent material has a refractive index similar to that of La₃Si₆N₁₁The same crystal structure.

3. Use according to claim 1 or 2, wherein D is Dy;

a is Si;

m is La.

4. Use according to claim 1 or 2, wherein D is Pr;

a is Si;

m is La.