KR101516522B1 - Lutetium garnet phosphor and light emitting diodes comprising the same - Google Patents

Abstract

The present invention relates to a novel lutetium garnet fluorescent material having excellent structural stability and color rendering property and a light emitting device including the same.

Description

TECHNICAL FIELD [0001] The present invention relates to a lutetium garnet fluorescent material, and a luminescent device containing the lutetium garnet fluorescent material. BACKGROUND ART [0002] LUTETIUM GARNET PHOSPHOR AND LIGHT EMITTING DIODES COMPRISING THE SAME [0003]

The present invention is based on the composition formula of (Lu _{1- a- b} Zn _a Gd _b ) _3-x (Al _{1 -c- d} Mo _c Ga _d ) ₅ O ₁₂ : Re _x and has excellent structural stability and excellent color rendering To a novel lutetium garnet fluorescent material and a light emitting device comprising the same.

BACKGROUND ART [0002] In recent years, white LED light emitting devices, which are widely used for illumination, LCD backlighting, automobile lighting, and the like, use an LED light emitting device that emits blue or near ultraviolet light and a light emitted from the light emitting device as excitation sources And a phosphor.

These white as how to implement the LED, using a blue LED with the InGaN-based material having a wavelength of 450 ~ 550nm as a conventional light emitting device, the phosphor (Y, Gd) of _{3 (Al, Ga) 5 O} 12 composition formula The YAG-base phosphor of yellow light emission represented by the following formula is typically used. This white LED is repeatedly absorbed and scattered in the phosphor layer by causing the blue light emitted from the light emitting element to enter into the phosphor layer. In this process, the blue light absorbed by the phosphor is converted into yellow light, which is wavelength- Are mixed and appear white in the human eye.

However, the white LED of the above-described structure has a problem that only red light is less in red component, color temperature is high, and red and green components are insufficient to obtain only an illumination light with poor color rendering property.

SUMMARY OF THE INVENTION The present invention has been conceived to solve the problems described above, and it is an object of the present invention to provide an organic electroluminescent device which has a garnet system structure and is excellent in structural stability and has a luminescent property in green or yellow band, And a lutetium garnet fluorescent material which can be suitably used in the LED field in particular.

Another object of the present invention is to provide a luminescent device comprising the aforementioned lutetium garnet fluorescent substance.

In order to solve the above-mentioned problems, the present invention provides a lutetium garnet fluorescent material characterized by the following formula (1).

[Chemical Formula 1]

_{(Lu 1 -a- b Zn a Gd} b) 3-x (Al 1 -c- d Mo c Ga d) 5 O 12: Re x

In Formula 1,

a is 0? a? 0.05,

b is 0? b? 0.08,

c is 0? c? 0.05,

d is 0? d? 0.15,

x is 0.01? x? 0.1, provided that a + b> 0, c + d> 0,

Re is a rare earth element and at least one element selected from the group consisting of Ce, Mn, Pr, Eu, Nd, Sm, Dy, Ho, Er, Tm and Yb.

According to a preferred embodiment of the present invention, in Formula 1, a and c are 0.01? A? 0.05; 0.01? C? 0.05.

According to a preferred embodiment of the present invention, the lutetium garnet fluorescent material may exhibit an emission peak wavelength of 515 to 560 nm with respect to excitation light having a peak wavelength range of 250 to 550 nm.

According to another preferred embodiment of the present invention, the average particle size of the lutetium garnet fluorescent material may be in the range of 1 to 20 μm, and the full width-at-half-maximum (FWHM) have.

On the other hand, the present invention provides a light emitting device comprising the aforementioned lutetium garnet fluorescent substance.

More specifically, the light emitting device includes a light emitting device that emits excitation light and a wavelength converting unit that absorbs the excitation light to emit visible light, and the wavelength converting unit includes the above-described lutetium garnet fluorescent material .

According to a preferred embodiment of the present invention, the light emitting device may be an ultraviolet light emitting diode or a blue light emitting diode.

The novel lutetium garnet fluorescent material of the present invention is excellent in structural stability based on the garnet system structure and can control the luminescent color in green or yellow depending on the control of the activator. It is also easy to improve the luminescence brightness, and can be particularly useful in LED fields.

Fig. 1 is a graph comparing XRD patterns of the lutetium garnet fluorescent material and the YAG fluorescent material prepared in Example 1. Fig.
FIG. 2 is a graph comparing PL emission measurement values of the lutetium garnet fluorescent material and the YAG fluorescent material prepared in Example 1. FIG.
3 is a graph showing PL excitation measurement results of the lutetium garnet fluorescent material prepared in Example 1. Fig.
FIG. 4 is a graph comparing the measured PL emission values of the lutetium garnet phosphors prepared in Examples 1 to 3, respectively.
FIG. 5 is a graph showing a PL emission measurement result showing the movement of luminescence peaks of the lutetium garnet phosphors of Examples 4 to 10 according to the concentration conditions of the activator Ce.

Hereinafter, the present invention will be described in detail.

<Lutetium garnet-based phosphor>

The lutetium garnet fluorescent material according to the present invention comprises (i) at least two elements selected from the group consisting of Lu, Zn, and Gd; And (ii) a garnet structure in which at least two elements selected from the group consisting of Al, Mo and Ga are formed to form a matrix and a rare earth element is activated as an activator, 1 &lt; / RTI &gt;

Unlike a conventionally known lutetium garnet fluorescent material (commonly referred to as a LuAG fluorescent material), in the present invention, the reaction temperature is lowered due to the low melting point of ZnO and MoO used in the production of the lutetium garnet fluorescent material, Thereby increasing the structural stability.

Further, when Ce or the like is dissolved as a metal element of the active agent to be solved and the concentration thereof is adjusted, the emission peak can be adjusted from green to yellow when the ultraviolet ray or visible ray is irradiated with the excitation source, A phosphor for a light-emitting element such as a diode, and the like. Accordingly, a light emitting device, particularly a light emitting device capable of emitting white light, can be realized using the light emitting device and the phosphor composition including the lutetium garnet fluorescent material.

Particularly, the phosphor of the present invention improves the emission intensity of the blue wavelength in the short wavelength region by adding Zn and Mo to the composition of the garnet fluorescent material, and thereby the energy transfer efficiency of the LED blue chip is excellent when the red phosphor and the white LED are realized.

In the present invention, the rare earth element contained in the lutetium garnet fluorescent material may be used without limitation in a conventional rare earth element known in the art. Ce, Pr, Eu, Nd, Sm, Dy, Ho, Er, Tm, Yb or a combination of at least one of them. Or more, and more preferably Ce.

When a rare earth element is used as the activator component, it is preferable to use cerium (Ce) alone, or to mix Ce and other rare earth elements. At this time, the mixing ratio of Ce and other rare earth elements is not particularly limited, but in the case of 92 to 97: 3 to 8 weight ratio, the luminous efficiency can be further improved.

In the case of the lutetium garnet fluorescent material according to the present invention, when the composition condition is out of the above-described formula (1), the crystal structure is changed to a crystal structure other than the garnet system, and the characteristics of the intended phosphor can not be obtained. Therefore, the lutetium garnet fluorescent material having improved crystallinity can be obtained by adding Zn and Mo contained therein only when the composition satisfies the general formula and the composition range of the formula (1). For example, when Zn and Mo exceeding the above-described composition range are contained, an amorphous phase or other crystalline phase is formed as an unreacted material after the phosphor is formed. Since such unreacted materials lower the emission intensity of the phosphor itself, the unreacted materials should be contained within the composition range represented by the above formula (1).

The lutetium garnet fluorescent material satisfying the composition formula of the above-mentioned formula (1) exhibits the luminescence peak wavelength in the range of 515 to 560 nm, preferably 520 to 550 nm, with respect to the excitation light having the luminescence peak wavelength of 250 to 550 nm.

The lutetium garnet fluorescent material preferably contains at least two elements selected from among at least Lu, Zn and Gd and at least two elements selected from Al, Mo and Ga as a matrix constituent element, and is a rare earth element, (FWHM, full-width-at-half-maximum) of the emission wavelength range is widened by 104 nm or more, so that the blue region is increased and the energy transfer efficiency of the LED blue chip is improved And brightness and thermal stability can be improved.

In the present invention, the average particle size of the lutetium garnet fluorescent material is preferably in the range of 1 to 20 mu m. If the average particle size of the phosphor is smaller than 1 占 퐉, the light absorption rate due to scattering decreases, and uniform dispersion of the phosphor into the resin sealing the LED may not be easy. If the average particle size of the phosphor is more than 20 mu m, the emission intensity and color tone may be uneven.

&Lt; Process for producing lutetium garnet fluorescent material &

Hereinafter, a method for producing the lutetium garnet fluorescent material according to the present invention will be described. However, the present invention is not limited to the following production methods, and the steps of each process may be modified or optionally mixed as required.

A preferred example of the method for producing the lutetium garnet fluorescent material includes (a) a compound containing two or more elements selected from the group consisting of Lu, Zn, and Gd; A compound containing two or more elements selected from the group consisting of Al, Mo, and Ga; And a rare earth element, respectively, in a nitrogen atmosphere; And firing the reaction mixture obtained in the above step in a nitrogen-containing atmosphere.

Hereinafter, the manufacturing method will be described separately for each step.

First, (1) a compound containing at least two elements selected from the group consisting of Lu, Zn, and Gd; A compound containing two or more elements selected from the group consisting of Al, Mo, and Ga; And a rare earth element are mixed in a nitrogen atmosphere to obtain a reaction mixture (hereinafter referred to as "first step").

As a raw material for producing the phosphor, oxide is mainly used. When Lu, Zn, Gd, Al, Mo, Ga, and Ce are used as the main components of the phosphor, lutetium oxide (Lu ₂ O ₃ ), zinc oxide (ZnO), gadolinium oxide (Gd ₂ O ₃ ) Aluminum (Al ₂ O ₃ ), molybdenum oxide (MoO ₂ ), gallium oxide (Ga ₂ O ₃ ), cerium oxide (CeO ₂ ), or a mixed powder thereof may be used.

In the first step, raw materials such as Lu ₂ O ₃ , ZnO, Al ₂ O ₃ , MoO ₂ , CeO ₂ Weigh and mix. The amount of mixture per sample should be 1 g.

The oxide of the rare earth element may be at least one selected from the group consisting of Ce, Pr, Ne, Sm, Eu, Gd, Terbium, Dy, Ho), erbium (Er), thulium (Tm) and ytterbium (Yb), preferably cerium oxide.

In the first step, the raw materials may be pulverized to control the particle size to be small. As the pulverization method, a dry or wet method known in the art can be used, and examples thereof include, but are not limited to, mortar mill, ball mill, jet mill, impact mill, mortar and the like.

The mixing process of the raw materials may be performed manually in an atmospheric environment. The mixing time of the raw materials is not particularly limited, but may be about 5 minutes to 30 minutes.

(2) Thereafter, the reaction mixture obtained in the first step is fired in a nitrogen-containing atmosphere to obtain a phosphor (hereinafter referred to as a 'second step').

The second step is performed in a nitrogen-containing atmosphere in order to prevent or suppress the decomposition of the phosphor synthesized during the high-temperature firing.

Examples of the nitrogen-containing atmosphere include an N ₂ gas atmosphere, an H ₂ and N ₂ mixed gas atmosphere, and preferably a H ₂ and N ₂ mixed gas atmosphere. Although the mixing ratio of hydrogen and nitrogen in the H ₂ and N ₂ mixed gas atmosphere is not particularly limited, when the ratio of H ₂ : N ₂ = 5 to 25: 75 to 95 volume, the phosphor synthesized during high-temperature firing is prevented from decomposing Or can be suppressed, and the compositional deviation of the generated phosphor can be reduced, and a phosphor excellent in performance can be produced. The pressure of the nitrogen-containing atmosphere is not particularly limited, but may be in the range of atmospheric pressure to 20 atmospheres.

In the second step, the baking temperature is not particularly limited, but is preferably in the range of 1400 to 1700 ° C, and more preferably 1500 ° C or more to obtain a high-quality phosphor.

The baking time is not particularly limited, but may be, for example, about 30 minutes to 48 hours, and preferably about 3 hours to 8 hours in consideration of the quality and productivity of the phosphor.

In one preferred embodiment of the second step, firing may be performed at a firing temperature of 1600 캜 for 4 hours in a mixed gas atmosphere of normal pressure nitrogen (75%) and hydrogen (25%).

After the second step, the phosphor may further be pulverized. By controlling the average particle size of the phosphor to be in the range of about 1 to 20 mu m by pulverizing the phosphor, the light emitting element can be uniformly dispersed in the sealing resin sealing the light emitting element, deterioration of the light absorption rate due to scattering can be prevented, And the color tone can be made uniform.

&Lt; Light emitting device including lutetium garnet fluorescent material &

The present invention provides a light emitting device comprising an oxide-based yellow phosphor represented by the above-mentioned formula (1).

For example, the light emitting device includes a light emitting element that emits (emits) excitation light; And a wavelength converter disposed at a light emitting side of the light emitting device and including a lutetium garnet fluorescent material represented by Formula 1 and a sealing resin.

The light emitting element is a light source that emits (emits) excitation light such as blue light. Examples of the light emitting element include a light emitting diode (LED), a laser diode (LD), and a light source emitting (emitting) blue light.

The wavelength of the excitation light is not particularly limited, but when the wavelength is 250 to 550 nm, the excitation light and the yellow light emitted by the phosphor may be combined to form a natural white color.

The wavelength converting part includes the lutetium garnet fluorescent material of the formula (1) and the sealing resin, and may alternatively include other luminescent materials known in the art, in addition to the lutetium garnet fluorescent material of the formula (1).

Such a wavelength converting portion is molded on the light emitting element through a molding process such as transfer molding, as is known in the art.

The sealing resin is a binder resin and can be used without particular limitation as long as it is transparent and has adhesiveness. For example, epoxy resin, silicone resin, urethane resin, acrylic resin, and the like, but are not limited thereto.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the following examples serve to illustrate the present invention, and the scope of the present invention is not limited thereto.

In the meantime, the following Example 1 is for confirming the XRD pattern of the typical composition of the lutetium garnet fluorescent material of the present invention, and Examples 2 to 3 show the composition corresponding to the composition formula range of the present invention. Further, Examples 4 to 10 show changes in the emission peak by controlling the concentration ratio of Ce to the phosphor composition of Example 1 differently. Hereinafter, the lambda value of the PL measurement condition in this figure was measured at 450 nm.

[Example 1]

As the raw material powder, Lu ₂ O ₃ 0.6290 g, ZnO 0.0083 g, Gd ₂ O ₃ 0.0248g, Al ₂ O ₃ 0.2645g, MoO ₂ 0.0222 g, Ga ₂ O ₃ 0.0393g and CeO ₂ Were weighed out, respectively, and were then mixed manually by induction in an air atmosphere to obtain 1 g of a raw material powder mixture. 1 g of the raw powder mixture thus mixed was charged into a crucible and fired by heating the mixture at a temperature of 1600 占 폚 for 4 hours by flowing 500cc of a mixed gas of hydrogen (25%) and nitrogen (75% And pulverized to obtain the lutetium garnet fluorescent material of Example 1.

It was confirmed that the lutetium garnet fluorescent material of Example 1 emitted at a central peak of 536 nm when a 450 nm excitation source was used (see FIG. 2).

[Example 2]

As the raw material powder, 0.6375 g of Lu ₂ O ₃ , , 0.0252 g of Gd ₂ O _3, 0.2770 g of Al ₂ O _3, 0.0398 g of Ga ₂ O _{3 and} 0.0121 g of CeO ₂ were respectively weighed and subjected to the same calcination and pulverization process as in Example 1 to obtain lutetium To obtain a garnet fluorescent material.

The lutetium garnet fluorescent material of Example 2 was found to emit light at a center peak of 541 nm when a 450 nm excitation source was used (see FIG. 4).

[Example 3]

As the raw material powder, Lu ₂ O ₃ 0.6162 g, Gd ₂ O ₃ 0.0492g, Al ₂ O ₃ 0.2619g, MoO ₂ 0.0220 g, 0.0389 g of Ga ₂ O _{3 and} 0.0389 g of CeO ₂ Were weighed and subjected to the same calcination and pulverization steps as in Example 1 to obtain the lutetium garnet fluorescent material of Example 3.

The lutetium garnet fluorescent material of Example 3 was found to emit light at a center peak of 544 nm when a 450 nm excitation source was used (see FIG. 4).

[Example 4]

As raw material powders, 0.6349 g of Lu ₂ O _3, 0.0084 g of ZnO, 0.0251 g of Gd ₂ O _3, 0.2643 g of Al ₂ O _3, 0.0222 g of MoO ₂ , Ga ₂ O ₃ 0.0392g and CeO ₂ Were weighed and subjected to the same calcination and pulverizing process as in Example 1 to obtain the lutetium garnet fluorescent material of Example 4.

The lutetium garnet fluorescent material of Example 4 was found to emit at a center peak of 517 nm when a 450 nm excitation source was used (see FIG. 5).

[Example 5]

As raw material powders, 0.6230 g of Lu ₂ O _3, 0.0082 g of ZnO, 0.0246 g of Gd ₂ O _3, 0.2647 g of Al ₂ O _3, 0.0222 g of MoO ₂ , Ga ₂ O ₃ 0.0393g and CeO ₂ Were weighed and subjected to the same calcining and pulverizing process as in Example 1 to obtain the lutetium garnet fluorescent material of Example 5.

The lutetium garnet fluorescent material of Example 5 emitted light with a center peak of 534 nm when a 450 nm excitation source was used (see FIG. 5).

[Example 6]

As raw material powders, 0.6171 g of Lu ₂ O _3, 0.0081 g of ZnO, 0.0244 g of Gd ₂ O _3, 0.2649 g of Al ₂ O _3, 0.0222 g of MoO ₂ , Ga ₂ O ₃ 0.0393g and CeO ₂ 0.0239 g were weighed, respectively, and then subjected to the same calcination and pulverization as in Example 1 to obtain the lutetium garnet fluorescent material of Example 6.

It was confirmed that the lutetium garnet fluorescent material of Example 6 emitted light with a center peak of 535 nm when a 450 nm excitation source was used (see FIG. 5).

[Example 7]

As raw material powders, 0.6111 g of Lu ₂ O _3, 0.0081 g of ZnO, 0.0241 g of Gd ₂ O _3, 0.2651 g of Al ₂ O _3, 0.0222 g of MoO ₂ , Ga ₂ O ₃ 0.0394g and CeO ₂ 0.0299 g were weighed out, and then the same luting and grinding steps as in Example 1 were carried out to obtain the lutetium garnet fluorescent material of Example 7.

It was confirmed that the lutetium garnet fluorescent material of Example 7 emitted light with a center peak of 539 nm when a 450 nm excitation source was used (see FIG. 5).

[Example 8]

As the raw material powder, 0.6052 g of Lu ₂ O _3, 0.0080 g of ZnO, 0.0239 g of Gd ₂ O _3, 0.2653 g of Al ₂ O _3, 0.0223 g of MoO ₂ , Ga ₂ O ₃ 0.0394g and CeO ₂ Were weighed and subjected to the same calcination and pulverizing process as in Example 1 to obtain the lutetium garnet fluorescent material of Example 8.

The lutetium garnet fluorescent material of Example 8 emitted light with a center peak of 536 nm when a 450 nm excitation source was used (see FIG. 5).

[Example 9]

As raw material powders, 0.5992 g of Lu ₂ O _3, 0.0079 g of ZnO, 0.0237 g of Gd ₂ O _3, 0.2655 g of Al ₂ O _3, 0.0223 g of MoO ₂ , Ga ₂ O ₃ 0.0394g and CeO ₂ Were weighed and subjected to the same calcination and pulverizing process as in Example 1 to obtain the lutetium garnet fluorescent material of Example 9.

It was confirmed that the lutetium garnet fluorescent material of Example 9 emitted light with a center peak of 543 nm when a 450 nm excitation source was used (see FIG. 5).

[Example 10]

As raw material powders, 0.5933 g of Lu ₂ O ₃ , 0.0078 g of ZnO, 0.0234 g of Gd ₂ O ₃ , 0.2657 g of Al ₂ O ₃ , 0.0223 g of MoO ₂ , 0.0395 g of Ga ₂ O _{3 and} 0.0480 g of CeO ₂ were respectively weighed and subjected to the same calcination and pulverization process as in Example 1 to obtain the lutetium garnet fluorescent material of Example 10.

The lutetium garnet fluorescent material of Example 10 emitted light with a center peak of 549 nm when a 450 nm excitation source was used (see FIG. 5).

Example Raw material mixing ratio center
wavelength
(nm) Lu ₂ O ₃ ZnO Gd ₂ O ₃ Al ₂ O ₃ MoO ₂ Ga ₂ O ₃ CeO ₂ One 0.6290 0.0083 0.0248 0.2645 0.0222 0.0393 0.0119 536 2 0.6375 0.0084 0.0252 0.2770 - 0.0398 0.0121 541 3 0.6162 - 0.0492 0.2619 0.0220 0.0389 0.0118 544 4 0.6349 0.0084 0.0251 0.2643 0.0222 0.0392 0.0060 517 5 0.6230 0.0082 0.0246 0.2647 0.0222 0.0393 0.0179 534 6 0.6171 0.0081 0.0244 0.2649 0.0222 0.0393 0.0239 535 7 0.6111 0.0081 0.0241 0.2651 0.0222 0.0394 0.0299 539 8 0.6052 0.0080 0.0239 0.2653 0.0222 0.0394 0.0359 536 9 0.5992 0.0079 0.0237 0.2655 0.0223 0.0394 0.0420 543 10 0.5933 0.0078 0.0234 0.2657 0.0223 0.0395 0.0480 549

The lutetium garnet fluorescent material thus prepared was subjected to XRD measurement, PL emission and excitation photography in the case of Example 1. In Examples 4 to 10, PL spectra were plotted to show the shift of the luminescence center peak, and the center wavelengths are shown in the table, and the PL emission graph corresponding thereto is shown in the figure.

The present invention is not limited by the above-described embodiments and compositions, but is intended to be limited by the appended claims. It will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. something to do.

Claims (7)

A lutetium garnet fluorescent material characterized by being represented by the following formula (1)
[Chemical Formula 1]
(Lu _1-ab Zn _a Gd _b ) _3-x (Al _1-cd Mo _c Ga _d ) ₅ O ₁₂ : Re _x
In Formula 1,
a is 0? a? 0.05,
b is 0? b? 0.08,
c is 0? c? 0.05,
d is 0? d? 0.15,
x is 0.01? x? 0.1, provided that a + b> 0, c + d> 0,
Re is at least one rare earth element selected from the group consisting of Ce, Mn, Pr, Eu, Nd, Sm, Dy, Ho, Er, Tm and Yb. The method according to claim 1,
Wherein the rare earth element is cerium (Ce). The method according to claim 1,
And exhibits an emission peak wavelength of 515 to 560 nm with respect to excitation light having a peak wavelength range of 250 to 550 nm. The lutetium garnet fluorescent material according to claim 1, wherein the average particle size is in the range of 1 to 20 mu m. A light emitting element that emits excitation light; And
And a wavelength conversion unit that absorbs the excitation light to emit visible light,
Wherein the wavelength converting portion comprises the lutetium garnet fluorescent material according to any one of claims 1 to 4. 6. The method of claim 5,
Wherein the light emitting element is an ultraviolet light emitting diode or a blue light emitting diode. 6. The method of claim 5,
Wherein the excitation light has an emission wavelength in the range of 250 to 550 nm.

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