KR100843423B1 - Surface coated silicate phosphor and light emitting device having the same - Google Patents

Abstract

A phosphor based on surface-coated silicate is provided to realize excellent reliability and reduce deterioration, and to obtain a light emitting device capable of stably emitting light with a desired color combination. A phosphor based on surface-coated silicate comprises: silicate phosphor particles; and a coating agent coated on the surface of the silicate phosphor particles and comprising at least one of boron, silicon and phosphorus compounds. The silicate phosphor particle has a composition of: (3-x-y-z/2)SrO.xBaO.yCaO.zEu2O. (m-a)SiO2.aGeO2.bAl2O3.cX (wherein 0<=x<2.4, 0<=y<2.4, 0.005<z<1, 0.9<=m<=1.2, 0<=a<0.5, 0<=b<0.5, 0<=c<0.05, and X is at least one of Cl, Br and F); or (2-x-y-z/2)SrO. xBaO. yCaO. zEu2O. (ma)SiO2. aGeO2. bAl2O3. cX (wherein 0<=x<2.4, 0<=y<2.4, 0.005<z<1, 0.9<=m<=1.2, 0<=a<0.5, 0<=b<0.5, 0<=c<0.05, and X is at least one of Cl, Br and F).

Description

Surface-Coated Silicate Phosphors and Light-Emitting Devices Having The Same {Surface Coated Silicate Phosphor and Light Emitting Device Having the Same}

1 is a cross-sectional view of a light emitting device according to an embodiment of the present invention.

2 is a graph showing test results of deterioration characteristics of light emitting devices of Examples and Comparative Examples.

3 is a graph showing changes in x-coordinates of color coordinates according to deterioration characteristic test times for light emitting devices of Examples and Comparative Examples.

4 is a graph showing a change in the y coordinate of the color coordinates according to the deterioration characteristic test time for the light emitting devices of Examples and Comparative Examples.

FIG. 5 is a graph showing changes in color coordinates according to deterioration characteristic test time for light emitting device samples of a comparative example. FIG.

FIG. 6 is a graph showing a change in color coordinates according to deterioration characteristic test time for light emitting device samples of the embodiment. FIG.

<Description of the symbols for the main parts of the drawings>

100: light emitting device 101: package body

101a: reflecting cup 105: LED element

107: surface coating phosphor 109: resin encapsulation

The present invention relates to a light emitting device having a combination of a phosphor and a light emitting diode and a phosphor used therein. More particularly, the present invention relates to a surface-coated silicate-based phosphor having low degradation and excellent reliability, and a surface-coated silicate-based phosphor and an LED device. A light emitting device constituted in combination.

Recently, attention has been paid to a light emitting device having a blue to ultraviolet LED element and a phosphor that emit light in a wavelength range of 350 nm to 500 nm. In such a light emitting device, the phosphor absorbs primary light from the LED element and emits secondary light having a wavelength larger than the wavelength of light of the LED element. Among these light emitting devices, a blue GaN-based LED device and a phosphor absorbing a part of the blue light to emit yellow light, and output white light by mixing blue light generated in the blue GaN-based LED device with yellow light generated from the phosphor. There is an LED device. Such a white LED device has attracted attention as a new light source replacing a small lamp, a fluorescent lamp, and the like, and is now widely used for backlights of small liquid crystal displays such as mobile phones. In addition, the use of the white LED light emitting device as a light source for various purposes such as backlight and lighting of medium and large liquid crystal display devices has been expanded.

As a yellow phosphor used for a white LED device, YAG: Ce, TAG: Ce, BOSE, etc. are proposed and currently used. In addition, a light emitting device manufactured by a combination of an LED device and Sr ₃ SiO ₅ : Eu which is a phosphor of orange light emission has been proposed. However, a white light emitting device using a combination of a blue LED and the yellow phosphor described above has a relatively low light intensity in a long wavelength (red wavelength region), and thus it is difficult to realize desired color reproducibility. In addition, even in an LED device using a combination of a blue LED and an orange phosphor, there is a problem in that a white color having a good color rendering index cannot be obtained due to a low y value on the CIE chromaticity diagram.

In order to improve this problem, it is proposed to add a green phosphor to a blue LED and an Sr ₃ SiO ₅ : Eu orange phosphor to obtain pure white. As such a green phosphor, (Ba, Sr) ₂ SiO ₄ : Eu or the like may be used. However, the crystal structure of orange light-emitting Sr ₃ SiO ₅ : Eu is easily unstable by the external environment (temperature, humidity, etc.), and thus the degree of deterioration of the phosphor is high at high temperature and high humidity. Also in the (Ba, Sr) ₂ SiO ₄ : Eu phosphor, deterioration occurs due to exposure to the external environment, and therefore improvement or change of the phosphor material is preferable. Such deterioration of the phosphor is severe with the passage of the use time, so that the light emitting device employing the phosphor also suffers from deterioration and shortening of life.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a phosphor having excellent reliability and less deterioration.

Another object of the present invention is to provide a light emitting device which is capable of stably outputting a desired color sum light such as white light by providing a phosphor and an LED element with little degradation and high reliability.

In order to achieve the above technical problem, the phosphor according to an aspect of the present invention, silicate phosphor particles; Coated on a surface of the silicate phosphor particles, the coating comprising at least one of boron, silicon and phosphorus compounds, wherein the composition of the silicate phosphor particles,

(3-xyz / 2) SrO.xBaO.yCaO.zEu ₂ O. (ma) SiO ₂ .aGeO ₂ .bAl ₂ O ₃ .cX where x, y, z, m, a, b, and c are 0. ≤ x <2.4, 0 ≤ y <2.4, 0.005 <z <1, 0.9 ≤ m ≤ 1.2, 0 ≤ a <0.5, 0 ≤ b <0.5, 0 ≤ c <0.05, and X is Cl, Br, F At least one), or

(2-xyz / 2) SrO.xBaO.yCaO.zEu ₂ O. (ma) SiO ₂ .aGeO ₂ .bAl ₂ O ₃ .cX where x, y, z, m, a, b, and c are 0. ≤ x <2.4, 0 ≤ y <2.4, 0.005 <z <1, 0.9 ≤ m ≤ 1.2, 0 ≤ a <0.5, 0 ≤ b <0.5, 0 ≤ c <0.05, and X is Cl, Br, F At least one).

According to an embodiment of the present invention, the boron compound forming the coating may be at least one of boron oxide, boric acid and borate. In addition, the silicon compound forming the coating may be at least one of silicon oxide and silicate. In addition, the phosphorus compound forming the coating may be at least one of pyrophosphoric acid, polyphosphoric acid and phosphate.

In order to achieve another object of the present invention, a light emitting device according to an aspect of the present invention, the LED element; And a phosphor that absorbs the emitted light of the LED device and emits light having a wavelength greater than that of the emitted light, wherein the phosphor includes silicate phosphor particles coated with a coating of at least one of boron, silicon, and phosphorus compounds. The silicate phosphor particles include at least one of a first phosphor particle having a first composition formula and a second phosphor particle having a second composition formula.

First Composition Formula: (3-xyz / 2) SrO.xBaO.yCaO.zEu ₂ O. (ma) SiO ₂ .aGeO ₂ .bAl ₂ O ₃ .cX (where x, y, z, m, a, b c is 0≤x <2.4, 0≤y <2.4, 0.005 <z <1, 0.9≤m≤1.2, 0≤a <0.5, 0≤b <0.5, 0≤c <0.05, and X is Cl, At least one of Br, F).

Second Composition Formula: (2-xyz / 2) SrO.xBaO.yCaO.zEu ₂ O. (ma) SiO ₂ .aGeO ₂ .bAl ₂ O ₃ .cX (where x, y, z, m, a, b c is 0≤x <2.4, 0≤y <2.4, 0.005 <z <1, 0.9≤m≤1.2, 0≤a <0.5, 0≤b <0.5, 0≤c <0.05, and X is Cl, At least one of Br, F).

According to an embodiment of the present invention, the boron compound may be selected from at least one of boron oxide, boric acid and borate. In addition, the silicon compound may be selected from at least one of silicon oxide and silicate. In addition, the phosphorus compound may be at least one of pyrophosphoric acid, polyphosphoric acid and phosphate.

According to an embodiment of the present invention, the light emitting device further includes a package body having a cup portion concave at the top, and a translucent resin encapsulant disposed in the cup portion, wherein the LED element comprises: It is mounted on the floor and encapsulated by the resin encapsulant, and the phosphor may be disposed on the LED element in the cup part.

According to an embodiment of the present invention, the LED device may be a semiconductor LED device emitting blue light or ultraviolet light. The light emitting device may be a white LED device that outputs white light. In particular, the light emitting device includes the surface-coated first phosphor particles and another phosphor, wherein the surface-coated first phosphor particles emit orange light by absorbing the emitted light of the LED device, and the other phosphor. May absorb the emitted light of the LED device and emit green light. In addition, the other phosphor may include the surface-coated second phosphor particles.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Accordingly, the shape and size of elements in the drawings may be exaggerated for clarity.

1 is a cross-sectional view showing an example of a light emitting device according to an embodiment of the present invention. Referring to FIG. 1, the light emitting device 100 includes a package body 107 having a concave cup portion 101a and an LED element or LED chip 105 mounted on the bottom of the cup portion 101a. On the LED element 105 in the cup part 101a, the translucent resin packaging part 109, such as a silicone resin, is arrange | positioned, and the LED element 105 is sealed. In this resin packaging portion 109, phosphors 107 in the form of powder particles for wavelength conversion are dispersed.

In operation of the light emitting device 100, part of the light (primary light) emitted from the LED element 100 is absorbed by the phosphor 107. The phosphor 107 which absorbs light from the LED element 100 emits light (secondary light) having a wavelength larger than the wavelength of the absorbed light, and the primary light (not absorbed) and the secondary light are summed together with desired output light (for example, , White light). For example, the LED device may be a blue or ultraviolet LED device. In addition, the phosphor 107 may include a mixture of two or more kinds of phosphors or phosphors emitting orange light and green light. Phosphor 107 may act as a yellow phosphor through appropriate composition selection.

The phosphor 107 may be a single kind of phosphor or a combination of two or more kinds of phosphors. In order to solve the structural instability of the phosphor material, which has been a problem in the related art, the present inventors have a coating of at least one of boron, silicon, and phosphorus compounds on the surface of the silicate phosphor particles having the above-described composition (see the first or second composition formula). A coated 'surface coated silicate phosphor' is proposed.

Specifically, the phosphor 107 is obtained by coating with a coating of at least one of boron, silicon and phosphorus compounds on the surface of a silicate phosphor particle having a first composition formula and / or a silicate phosphor particle having a second composition formula. Phosphors (combinations of phosphors having a first composition and a second composition or mixtures of two or more phosphor particles are also possible).

* First composition formula: (3-xyz / 2) SrO.xBaO.yCaOzEu ₂ O. (ma) SiO ₂ aGeO ₂ bAl ₂ O ₃ cX (where x, y, z, m, a, b and c are 0≤x <2.4, 0≤y <2.4, 0.005 <z <1, 0.9≤m≤1.2, 0≤a <0.5, 0≤b <0.5, 0≤c <0.05, and X is Cl , Br, F).

* Second composition formula: (2-xyz / 2) SrO.xBaO.yCaO.zEu ₂ O. (ma) SiO ₂ .aGeO ₂ .bAl ₂ O ₃ .cX (where x, y, z, m, a, b and c are 0≤x <2.4, 0≤y <2.4, 0.005 <z <1, 0.9≤m≤1.2, 0≤a <0.5, 0≤b <0.5, 0≤c <0.05, and X is Cl , Br, F).

In such a surface-coated phosphor, not only the binding of the coating material and the silicate phosphor particles is good, but also the surface coating material can effectively block the damage of the phosphor particles due to an external environment, for example, an external temperature or humidity. Therefore, the surface-coated phosphor 107 having such a composition shows high reliability and the degree of degradation thereof is lower than that of the conventional silicate phosphor or sulfide phosphor (see FIG. 2). As a result, by using the phosphor 107 having a low degree of deterioration and excellent structural stability of the material, the light emitting device 100 using this as a wavelength conversion element has little deterioration and a long life.

The coating coated on the surface of the silicate phosphor particles having the first composition formula or the second composition formula may be formed of a boron compound, a silicon compound, or a phosphorus compound. The silicon compound that can be used as such coating material may be at least one selected from silicon oxide and silicate. In addition, the boron compound may be at least one selected from boron oxide, boric acid and borates, the phosphorus compound may be selected from at least one of pyrophosphoric acid, polyphosphoric acid and phosphate.

The light emitting device 100 is not limited thereto, but may be usefully used as a white LED device used for a backlight or a lighting fixture of an LCD device. For example, a surface-coated phosphor powder may be obtained by coating a surface of a silicate phosphor emitting orange light as a silicate phosphor having the first composition formula with a silicate material. A phosphor mixture of this surface-coated phosphor powder and another green phosphor (e.g., (Ba, Sr) ₂ SiO ₄ : Eu, etc.) was used as the phosphor 107 and combined with the blue GaN-based LED element 105. In addition, a highly reliable white light emitting device having good color reproducibility and little deterioration can be realized.

Here, instead of the (Ba, Sr) ₂ SiO ₄ : Eu green phosphor, surface coated silicate phosphor particles having the second composition formula (also emitting green light) may be used. Using the surface-coated silicate phosphor particles of the second composition formula further reduces degradation of the phosphor and the white light emitting device and further improves stability. Further improvement of this deterioration characteristic and stability is the result obtained by surface coating of the orange light silicate phosphor (having the first composition formula) and the green light silicate phosphor (having the second composition formula) with the coating as described above.

The present inventors implemented a phosphor and a light emitting device through various examples as follows. In addition, a characteristic deterioration test was performed on the light emitting device of Example and the light emitting device sample of Comparative Example to compare the degree of deterioration of both.

(Example 1)

Using strontium carbonate (SrCO ₃ ), europium oxide (Eu ₂ O ₃ ), silicon oxide (SiO ₂ ) as the phosphor raw material, the Sr: Eu: Si ratio is 2.935: 0.065: 1.1, mixed and prepared. In a nitrogen gas atmosphere containing 5% hydrogen in an alumina crucible, the product was calcined at a maximum temperature of 1550 ° C. for 5 hours at high temperature, and classified into a 50 μm sieve to obtain an orange light-emitting phosphor Sr ₃ SiO ₅ : Eu. Next, 3.0 g of the prepared Sr3SiO5: Eu phosphor was weighed and co-precipitated in 4.0 g of 4% H ₃ BO ₃ aqueous solution, thereby drying at 500 ° C. or lower to obtain an Sr 3 SiO 5: Eu phosphor coated with the boron compound of the present invention. .

The phosphor was mixed with the Sr2SiO4: Eu phosphor at a weight ratio of 2.5: 1, and then mixed with 1 weight ratio and 10 weight ratios of the silicone resin to make a slurry, and the slurry was then mounted on a cup on a mount lid equipped with a blue light emitting LED element. It injected | poured in, and it hardened | cured at 160 degreeC after injection | pouring for 1 hour, and the light emitting device of the white light emission provided with the fluorescent substance coated with the blue light emitting LED element and the boron compound.

(Example 2)

Sr ₃ SiO ₅ : Sr3SiO5: Eu coated with a silicon compound in the same manner as in Example 1 except that the phosphor was co-precipitated with 0.3 g of ethyl silicate instead of coprecipitating with 4.0 g of an aqueous solution of 4% H ₃ BO _3. A light emitting device of phosphor and white light emission was obtained.

(Example 3)

Sr ₃ SiO ₅ : A phosphoric acid compound was coated in the same manner as in Example 1 except that the Eu phosphor was co-precipitated in 1.8 g of 5% Na ₂ HPO ₄ aqueous solution instead of coprecipitating in 4.0 g of 4% H ₃ BO ₃ aqueous solution. Sr ₃ SiO ₅ : An Eu phosphor and a white light emitting device were obtained.

(Example 4)

Sr ₃ SiO ₅ : Replaced with Eu phosphor, the composition formula (Ba, Sr) ₂ SiO ₄ : Except for using Eu phosphor, the same procedure as in Example 1 was carried out (Ba, Sr) ₂ SiO ₄ : Eu phosphor coated with a boron compound And a light emitting device of white light emission.

(Example 5)

Sr ₃ SiO ₅ : Replaced with Eu phosphor, the same as in Example 1 except that phosphor of composition (Ba, Sr) ₂ SiO ₄ : Eu was used, and the boron compound was coated (Ba, Sr) ₂ SiO ₄ : Eu phosphor And a light emitting device of white light emission.

(Example 6)

As a phosphor raw material, Ca: Sr: Eu: Si ratio was used as calcium carbonate (CaCO ₃ ), strontium carbonate (SrCO 3), europium oxide (Eu ₂ O ₃ ), and silicon oxide (SiO ₂ ), and 0.005: 2.930: 0.065: the weighing and preparation so that the _{1.1, (Ca, Sr) 3} SiO 5: (Ca, Sr) to the same and the exception to get as Eu phosphor in example 1, the boron compound is a coating ₃ SiO _5: Eu phosphor and a white light-emitting The light emitting device of was obtained.

(Reliability test)

In order to confirm the deterioration characteristics of the phosphor and the white light emitting device of the present invention, the deterioration characteristic test of the LED device was carried out at a temperature of 80 ℃ and humidity of 80%. An example of the test result is shown in FIG. The sample of the example shown in FIG. 2 corresponds to Example 1 described above, and used an orange light-emitting Sr ₃ SiO ₅ : Eu phosphor coated with a boron compound, the orange silicate phosphor, and a blue GaN-based LED. And a white light emitting device (example) were implemented by combining green light emitting Sr ₂ SiO ₄ : Eu phosphor. On the other hand, the sample of the comparative example used a blue GaN-based LED, an orange light-emitting Sr ₃ SiO ₅ : Eu phosphor and a green light emitting Sr ₂ SiO ₄ : Eu phosphor to implement a white light emitting device. .

As shown in FIG. 2, it can be seen that the light emitting device sample of the example has a very small change in luminance IV according to deterioration characteristic test time, compared to the comparative example. The light emitting device sample of the example shows very high reliability under high temperature and high humidity, and its degree of deterioration is also very low. Thus, it can be seen that the samples of the examples can exhibit improved lifetime.

3 to 6 show graphs of the light emitting device samples (using Sr ₃ SiO ₅ : Eu phosphor coated with a boron compound) and the light emitting device samples (using uncoated Sr ₃ SiO ₅ : Eu phosphor) of the example described above. These graphs show the change in color coordinates of CIE 1931 with deterioration test time.

The sample of the examples and comparative examples shown in the graphs of FIGS. 3 to 6 were subjected to a degradation test for a total of 500 hours while flowing a DC current of 20 mA at 60 ° C. and 95% humidity. 3 and 4 show the average x coordinate change amount and the average y coordinate change amount of the plurality of example samples and the plurality of comparative example samples. The x coordinate change amount and the y coordinate change amount of FIGS. 3 and 4 may be expressed as shown in Table 1 below.

x-coordinate y coordinate time 0 250 500 0 250 500 After coating (Example) 0.312 0.307 0.296 0.308 0.303 0.287 Change 0.004904 0.015760 0.004644 0.020850 Before coating (comparative example) 0.284 0.232 0.209 0.272 0.230 0.207 Change 0.052200 0.075340 0.041220 0.064240

As shown in Table 1, FIG. 3 and FIG. 4, it can be seen that the x-coordinate change amount Δx and the y-coordinate change amount Δy of the examples are significantly smaller than those of the comparative example.

5 and 6 are graphs showing color coordinates of CIE 1931 (according to deterioration characteristic test time) of a plurality of comparative samples and a plurality of example samples. As shown in FIGS. 5 and 6, as the deterioration characteristic test time elapses, it can be seen that the variation of the color coordinates of the example samples is significantly smaller than those of the comparative examples.

After all, from the test results graph of FIGS. 3-6, the coated Sr ₃ SiO _5: light-emitting device using the Eu phosphor is an uncoated Sr ₃ SiO _5: The change in color coordinates significantly smaller than the light-emitting device using the Eu phosphor In addition, it can be clearly seen that it has a very high reliability and a long life.

The present invention is not limited by the above-described embodiment and the accompanying drawings, but is intended to be limited by the appended claims, and various forms of substitution, modification, and within the scope not departing from the technical spirit of the present invention described in the claims. It will be apparent to those skilled in the art that changes are possible.

As described above, according to the present invention, there is little degradation of the phosphor and high reliability of the material. Damage such as the collapse of the phosphor crystal structure due to heat or moisture is effectively prevented. In addition, by providing such a phosphor, the light emitting element can more stably emit output light having a desired color tone, and the deterioration of the light emitting element is also reduced.

Claims (13)

Silicate phosphor particles; And Coated on the surface of the silicate phosphor particles, the coating comprising at least one of boron, silicon and phosphorus compounds, The composition of the silicate phosphor particles is (3-xyz / 2) SrO.xBaO.yCaO.zEu ₂ O. (ma) SiO ₂ .aGeO ₂ .bAl ₂ O ₃ .cX (where x, y, z, m , a, b, c are 0≤x <2.4, 0≤y <2.4, 0.005 <z <1, 0.9≤m≤1.2, 0≤a <0.5, 0≤b <0.5, 0≤c <0.05, X is at least one of Cl, Br, F), or (2-xyz / 2) SrO.xBaO.yCaO.zEu ₂ O. (ma) SiO ₂ .aGeO ₂ .bAl ₂ O ₃ .cX, wherein x, y, z, m, a, b, c are 0≤x <2.4, 0≤y <2.4, 0.005 <z <1, 0.9≤m≤1.2, 0≤a <0.5, 0≤b <0.5, And 0 ≦ c <0.05 and X is at least one of Cl, Br, F). The method of claim 1, The boron compound forming the coating is a surface-coated phosphor, characterized in that at least one of boron oxide, boric acid and borate. The method of claim 1, And the silicon compound forming the coating is at least one of silicon oxide and silicate. The method of claim 1, The phosphor coated compound forming the coating is at least one of pyrophosphoric acid, polyphosphoric acid and phosphate. LED device; And It includes a phosphor for absorbing the emitted light of the LED device to emit light of a wavelength larger than the emitted light, The phosphor includes silicate phosphor particles surface-coated with a coating of at least one of boron, silicon and phosphorus compounds, wherein the silicate phosphor particles comprise a first phosphor particle having a first composition formula and a second composition formula. A light emitting device comprising at least one of two phosphor particles. First Composition Formula: (3-xyz / 2) SrO.xBaO.yCaO.zEu ₂ O. (ma) SiO ₂ .aGeO ₂ .bAl ₂ O ₃ .cX (where x, y, z, m, a, b c is 0≤x <2.4, 0≤y <2.4, 0.005 <z <1, 0.9≤m≤1.2, 0≤a <0.5, 0≤b <0.5, 0≤c <0.05, and X is Cl, At least one of Br, F). Second Composition Formula: (2-xyz / 2) SrO.xBaO.yCaO.zEu ₂ O. (ma) SiO ₂ .aGeO ₂ .bAl ₂ O ₃ .cX (where x, y, z, m, a, b c is 0≤x <2.4, 0≤y <2.4, 0.005 <z <1, 0.9≤m≤1.2, 0≤a <0.5, 0≤b <0.5, 0≤c <0.05, and X is Cl, At least one of Br, F). The method of claim 5, The boron compound is at least one selected from boron oxide, boric acid and borates. The method of claim 5, The silicon compound is at least one selected from silicon oxide and silicate. The method of claim 5, The phosphorus compound is at least one selected from pyrophosphoric acid, polyphosphoric acid and phosphate. The method of claim 5, Further comprising a package body having a concave cup portion at the top, and a transparent resin packaging portion disposed in the cup portion, And the LED element is mounted on the bottom of the cup part and sealed by the resin encapsulant, and the phosphor is disposed on the LED element in the cup part. The method of claim 5, The LED device is a light emitting device, characterized in that the semiconductor LED device for emitting blue light or ultraviolet light. The method of claim 5, The light emitting device is a light emitting device, characterized in that a white LED device for outputting white light. The method of claim 11, The light emitting device includes the surface-coated first phosphor particles and another phosphor, wherein the surface-coated first phosphor particles absorb orange light emitted from the LED device and emit orange light. A light emitting device characterized by absorbing the emitted light of the LED element to emit green light. The method of claim 12, Wherein said other phosphor comprises said surface coated second phosphor particles.

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