WO2006041249A1 - White light emitting device - Google Patents
White light emitting device Download PDFInfo
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- WO2006041249A1 WO2006041249A1 PCT/KR2005/001046 KR2005001046W WO2006041249A1 WO 2006041249 A1 WO2006041249 A1 WO 2006041249A1 KR 2005001046 W KR2005001046 W KR 2005001046W WO 2006041249 A1 WO2006041249 A1 WO 2006041249A1
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- phosphors
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- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 35
- 239000000203 mixture Substances 0.000 claims abstract description 22
- 229910052710 silicon Inorganic materials 0.000 abstract description 10
- 238000000034 method Methods 0.000 description 16
- 238000005424 photoluminescence Methods 0.000 description 13
- 238000001354 calcination Methods 0.000 description 5
- 238000000103 photoluminescence spectrum Methods 0.000 description 5
- 238000009877 rendering Methods 0.000 description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 4
- 238000007796 conventional method Methods 0.000 description 4
- 230000005284 excitation Effects 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 229910019655 synthetic inorganic crystalline material Inorganic materials 0.000 description 3
- 229910052684 Cerium Inorganic materials 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 239000012190 activator Substances 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000010835 comparative analysis Methods 0.000 description 2
- 238000000695 excitation spectrum Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- PUZPDOWCWNUUKD-UHFFFAOYSA-M sodium fluoride Chemical compound [F-].[Na+] PUZPDOWCWNUUKD-UHFFFAOYSA-M 0.000 description 2
- DDFHBQSCUXNBSA-UHFFFAOYSA-N 5-(5-carboxythiophen-2-yl)thiophene-2-carboxylic acid Chemical compound S1C(C(=O)O)=CC=C1C1=CC=C(C(O)=O)S1 DDFHBQSCUXNBSA-UHFFFAOYSA-N 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- JNDMLEXHDPKVFC-UHFFFAOYSA-N aluminum;oxygen(2-);yttrium(3+) Chemical compound [O-2].[O-2].[O-2].[Al+3].[Y+3] JNDMLEXHDPKVFC-UHFFFAOYSA-N 0.000 description 1
- OYLGJCQECKOTOL-UHFFFAOYSA-L barium fluoride Chemical compound [F-].[F-].[Ba+2] OYLGJCQECKOTOL-UHFFFAOYSA-L 0.000 description 1
- 229910001632 barium fluoride Inorganic materials 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 1
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 150000002222 fluorine compounds Chemical class 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 239000002223 garnet Substances 0.000 description 1
- LNEPOXFFQSENCJ-UHFFFAOYSA-N haloperidol Chemical compound C1CC(O)(C=2C=CC(Cl)=CC=2)CCN1CCCC(=O)C1=CC=C(F)C=C1 LNEPOXFFQSENCJ-UHFFFAOYSA-N 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000013024 sodium fluoride Nutrition 0.000 description 1
- 239000011775 sodium fluoride Substances 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 229910019901 yttrium aluminum garnet Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
- C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
- C09K11/7766—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing two or more rare earth metals
- C09K11/77744—Aluminosilicates
-
- H01L33/502—
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
Definitions
- the present invention relates to a TAG phosphor and a White Light Emitting Diode (White LED) using the same. More specifically, the present invention relates to a phosphor having excellent emission brightness by inclusion of Si or Fe in the phosphor having a TbAG:Ce composition, and a white LED utilizing the same.
- the white LED is a next generation light emitting device potential capable of replacing conventionally used general lighting means.
- the white LED has advantages such as very low power consumption compared to conventional light sources, high photoluminescence efficiency and high brightness, long-term service life and rapid response time.
- Methods of manufacturing white LEDs may be broadly divided into the following 3 types: the first method is to use a combination of high-brightness red, green and blue LEDs, the second method is to coat red, green and blue light-emitting phosphors on a UV LED and finally, and the third method is to coat a blue LED with light-emitting phosphors.
- the first method using a combination of red, green and blue LEDs suffers from problems in that three diodes should be used in the form of one chip, thus resulting in an increase in volume.
- the second method involving coating red, green and blue light-emitting phosphors on the UV LED is disclosed in WO9839805.
- This method is the most ideal method of producing three-wavelength white light by transmission of UV light into three primary color phosphors.
- phosphors having good photoluminescence efficiency of UV light have yet to be developed.
- the last method of manufacturing the white LED by coating light-emitting phosphors on the blue LED is currently undergoing the most wide and extensive study.
- This method has advantages in that it is possible to achieve easy production due to the simplified structure of the white LED and it is also possible to obtain high-brightness white light.
- Such a method is disclosed in detail in WO9805078, filed by Nichia, a Japanese company. This method is also detailed in S. Nakamura, "The Blue Laser Diode", Springer-Verlag, P. 216-219, 1997.
- white light is produced by the combination of blue and yellow light such that the blue light emitted from the LED is absorbed by yttrium-aluminum garnet (Y 2 Al 5 Oi 2 :Ce 3+ ; YAG) phosphor which then emits yellow light.
- YAG-based light-emitting phosphors due to unique properties of their light-emitting wavelengths, exhibit relatively weak photoluminescence intensity in a red light region, thereby making it difficult to obtain superior color rendering characteristics, and are susceptible to color temperature. Therefore, YAG-based light-emitting phosphors are disadvantageously not suitable for use in environmental illumination or as an LCD color backlight source.
- the present invention has been made in view of the above problems, and it is an object of the present invention to provide a TAG phosphor having high photoluminescence intensity in a red light region, good color rendering properties, and high-brightness pure light emitting characteristics, and a white light emitting diode (white LED) utilizing the same.
- a phosphor having a composition of TbAG:Ce wherein the phosphor having a composition of TbAG:Ce is composed of a compositional formula of (Tbi- x Ce x ) 3 (Ali_ y M y ) 5 Oi2, wherein x is between 0.01 and 0.4, y is between 0.0 and 0.1, and M is selected from the group consisting of Si and Fe.
- y is preferably between 0.01 and 0.04, whereas if M is Fe, y is preferably between 0.01 and 0.02.
- the white photoluminescent device in accordance with the present invention comprises at least one light-emitting diode emitting light with a wavelength of 430 to 470 nm and a phosphor having a composition of TbAG:Ce, wherein the phosphor having a composition of TbAG:Ce is composed of a compositional formula of (Tbi- x Ce x ) 3 (Ali- y M y ) 5 O 12 , wherein x is between 0.01 and 0.4, y is between 0.0 and 0.1, and M is selected from the group consisting of Si and Fe.
- y is preferably between 0.01 and 0.04, whereas if M is Fe, y is preferably between 0.01 and 0.02.
- the phosphor in accordance with the present invention is primarily made of Tb and Al as a mother body, and Ce 3+ functions as an activator. Where the amount of cerium is less than 0.01, it is not sufficient to serve as the activator. In contrast, where the amount of cerium is greater than 0.4, this may undesirably cause lowering in brightness due to concentration quenching effects.
- Tb4 ⁇ 7 As raw materials for the phosphor in accordance with the present invention, mention may be made of Tb4 ⁇ 7 , AI 2 O 3 and CeO 2 , for example.
- SiO 2 or Fe 2 O 3 may be utilized. These materials are quantified within an optimal molar ratio, and are sufficiently mixed to obtain a uniform composition using a mixer. The resulting mixture is placed in a crucible, which is covered with a lid. Then, the mixture is introduced into an electric furnace and calcined by heating the mixture at a temperature of 1400 to 1600 ° C for 1 to 4 hours. If the calcination temperature is less than 1400° C, single-phase crystals are not completely formed and unreacted reactants or by-products are produced. In addition, if the calcination temperature is above 1600 ° C, irregularly shaped particles are formed, thus sharply lowering brightness.
- fluoride flux may be added to a calcination process.
- the quantity of fluoride used is preferably in the range of 7 to 15 wt%, relative to (TbI-XCe x )S(Al 1 - Y My) 3 Oi 2 . More preferred is 8 wt%.
- the fluoride utilized in the present invention may include, for example, barium fluoride, ammonium fluoride, sodium fluoride and alumina fluoride. Use of such fluorides in the calcination process enables easy attainment of single-phase phosphors and makes it possible to obtain high-brightness superior phosphors even at low synthesis temperatures.
- the calcined materials are cooled to room temperature and milled in vacuo or under water using a ball mill to obtain powdered phosphors having a diameter of 0.5 to 20 ⁇ m size.
- the thus- obtained phosphors having a stable phase of (Tbi_ x Ce x ) 3 (AIi- ySiy) 3 O 1 2 or (Tbi_ x Ce x ) 3 (Ali_ y Fe y ) 3 O1 2 are coated on a blue light- emitting diode chip with an emission wavelength near 460 nm made up of GaN or the like.
- phosphors Preferably, 1 to 40 wt% of phosphors are mixed with epoxy resins or silicon based resins and the resulting mixture is coated on the blue LED chip which is then cured at a temperature of 130 to 200 ° C to fabricate a white light-emitting diode.
- a white light source that achieves high quantum efficiency, desired color temperature (4500K to 8000K) and good color rendering characteristics by use of the single phosphor material in accordance with the present invention alone, and is suited to mass production.
- Fig. 1 is an XRD result of a TAG phosphor in accordance with the present invention
- Fig. 2 is an excitation spectrum of a TAG phosphor in accordance with the present invention
- Fig. 3 is a photoluminescence spectrum of a TAG phosphor in accordance with the present invention
- Fig. 4 is a photoluminescence spectrum result of a TAG phosphor based light-emitting diode in accordance with the present invention.
- Fig. 5 is a color coordinate of a TAG phosphor based light-emitting diode in accordance with the present invention.
- Example 1 Comparative analysis between the TAG phosphor prepared according to the present invention and a conventional phosphor is given as follows.
- Fig. 1 shows the results of X-ray diffraction (XRD) of (Tbo.gC ⁇ o.i) 3 (Ali_ySiy) 5 O12 phosphors prepared in accordance with the present invention.
- XRD X-ray diffraction
- FIG. 2 shows an excitation spectrum of (Tb 0 . 9 Ce 0- I) 3 (AIi- y Si y ) 5 O 12 phosphors prepared according to the present invention.
- Fig. 3 shows comparison between photoluminescence spectra measured under an excitation wavelength of 465 nm, with respect to Si concentrations in (Tbo.gCeo.i)3 (Ali_ y Si y ) 5O12 phosphors. As can be seen from Fig. 3, the red-band photoluminescence intensity is stronger in phosphors containing Si, as in the present invention, than in conventional TbsAlsO ⁇ Ce phosphors.
- Table 1 summarizes photoluminescence intensity of Tb 3 Al 5 ⁇ i 2 :Ce o .i(sample #0) phosphors prepared according to a conventional method and the (Tb 0 . 9 Ce 0-I ) 3 (Ali- y Si y ) 5 O 12 phosphors prepared according to the present invention measured under an excitation wavelength of 465 nm, based on the molar ratio of Si.
- Table 1 summarizes photoluminescence intensity of Tb 3 Al 5 ⁇ i 2 :Ce o .i(sample #0) phosphors prepared according to a conventional method and the (Tb 0 . 9 Ce 0-I ) 3 (Ali- y Si y ) 5 O 12 phosphors prepared according to the present invention measured under an excitation wavelength of 465 nm, based on the molar ratio of Si.
- Photoluminescence intensity (PL) was remarkably excellent in the range of 0.01 to 0.04 of the Si molar ratio.
- Si molar ratio was 0.01, it showed about 87% improvement in PL, as compared to a comparative example.
- Table 2 summarizes photoluminescence intensity of Tb 3 Al 5 Oi 2 :Ce o .i (sample #0) phosphors prepared according to a conventional method and the (Tb 0 . 9 Ce 0 .i) 3(Ali- y Fe y ) 5 Oi 2 phosphors prepared according to the present invention measured under an excitation wavelength of 465 run, based on the molar ratio of Fe.
- the following evaluation results illustrate properties of a white LED prepared by applying a mixture of the TAG phosphor prepared according to the present invention and a light-transmissive silicon resin to a 460 nm (In)GaN blue light-emitting diode chip, followed by curing and drying.
- Table 3 summarizes characteristics of Tb 3 Al 5 ⁇ i 2 :Ceo.i (sample #0) phosphors prepared according to a conventional method and the (Tbo.gCeo.i)3(Ali-. y Si y ) 5O1 2 phosphors with replacement of Si content with the range of 0.0 ⁇ y ⁇ 0.1, prepared according to the present invention, on the basis of the molar ratio.
- Reliability data is a proportion of sample with characteristics equal to or higher than given criteria, after heat treatment at 85 ° C for 500 hours.
- Si molar ratio 0.01 to 0.04
- remarkably excellent results were obtained, ;as compared to the conventional art.
- brightness increased by 47% and reliability was improved to 97.7%.
- Fig. 4 is a photoluminescence spectrum result of a light-emitting diode fabricated using (Tbo.gCeo.i)3(Alo.99Sio.o1) 5O12 phosphors prepared according to the present invention.
- Table 4 summarizes characteristics of Tb 3 Al 5 Oi 2 :Ceo. 1 (sample #0) phosphors prepared according to a conventional method and the (Tbo.gCeo.i)3(Ali_yFe y )5O12 with replacement of Fe content with the range of 0.0 ⁇ y ⁇ 0.1, prepared according to the present invention, on the basis of molar ratio.
- Table 4 summarizes characteristics of Tb 3 Al 5 Oi 2 :Ceo. 1 (sa conventional method and the (Tbo.gCeo.i)3(Ali_yFe y )5O12 with replacement of Fe content with the range of 0.0 ⁇ y ⁇ 0.1, prepared according to the present invention, on the basis of molar ratio.
- Reliability data is a proportion of sample with characteristics equal to or higher than given criteria, after heat treatment at 85° C for 500 hours.
- the Fe molar ratio of 0.01 to 0.02 exhibited remarkably excellent results, as compared to the conventional art. In particular, when the Fe molar ratio was 0.01, brightness increased by 37% and reliability was improved to 95.2%.
- Fig. 5 shows the measured result of a CIE (Commission international de l'Eclairage) color coordinate (X, Y) on a photoluminescence spectrum of a light-emitting diode fabricated using a TAG phosphor in accordance with the present invention. As can be seen from Fig. 5, X and Y coordinates exhibited excellent color rendering within the range of pure white color, high brightness and excellent reliability.
- CIE Commission international de l'Eclairage
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Abstract
The present invention relates to a phosphor having excellent emission brightness by inclusion of Si or Fe in the phosphor having a TbAG:Ce composition, and a white LED. The white photoluminescent device in accordance with the present invention comprises at least one light-emitting diode emitting light with a wavelength of 430 to 470 nm and a phosphor having a composition of TbAG:Ce, wherein the phosphor having a composition of TbAG:Ce is composed of a compositional formula of (Tb1-xCex) 3 (Al1_yMy) 5O12, wherein x is between 0.01 and 0.4, y is between 0.0 and 0.1, and M is selected from the group consisting of Si and Fe.
Description
WHITE LIGHT EMITTING DEVICE
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a TAG phosphor and a White Light Emitting Diode (White LED) using the same. More specifically, the present invention relates to a phosphor having excellent emission brightness by inclusion of Si or Fe in the phosphor having a TbAG:Ce composition, and a white LED utilizing the same.
Description of the Related Art
The white LED is a next generation light emitting device potential capable of replacing conventionally used general lighting means. The white LED has advantages such as very low power consumption compared to conventional light sources, high photoluminescence efficiency and high brightness, long-term service life and rapid response time.
Methods of manufacturing white LEDs may be broadly divided into the following 3 types: the first method is to use a combination of high-brightness red, green and blue LEDs, the second method is to coat red, green and blue light-emitting
phosphors on a UV LED and finally, and the third method is to coat a blue LED with light-emitting phosphors.
The first method using a combination of red, green and blue LEDs suffers from problems in that three diodes should be used in the form of one chip, thus resulting in an increase in volume.
The second method involving coating red, green and blue light-emitting phosphors on the UV LED is disclosed in WO9839805. This method is the most ideal method of producing three-wavelength white light by transmission of UV light into three primary color phosphors. However, phosphors having good photoluminescence efficiency of UV light have yet to be developed.
The last method of manufacturing the white LED by coating light-emitting phosphors on the blue LED is currently undergoing the most wide and extensive study. This method has advantages in that it is possible to achieve easy production due to the simplified structure of the white LED and it is also possible to obtain high-brightness white light. Such a method is disclosed in detail in WO9805078, filed by Nichia, a Japanese company. This method is also detailed in S. Nakamura, "The Blue Laser Diode", Springer-Verlag, P. 216-219, 1997. According to this method, white light is produced by the combination of blue and yellow light such that the blue light emitted from the LED is absorbed by yttrium-aluminum
garnet (Y2Al5Oi2:Ce3+; YAG) phosphor which then emits yellow light. However, YAG-based light-emitting phosphors, due to unique properties of their light-emitting wavelengths, exhibit relatively weak photoluminescence intensity in a red light region, thereby making it difficult to obtain superior color rendering characteristics, and are susceptible to color temperature. Therefore, YAG-based light-emitting phosphors are disadvantageously not suitable for use in environmental illumination or as an LCD color backlight source.
SUMMARY OF THE INVENTION
Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a TAG phosphor having high photoluminescence intensity in a red light region, good color rendering properties, and high-brightness pure light emitting characteristics, and a white light emitting diode (white LED) utilizing the same. In accordance with the present invention, the above and other objects can be accomplished by the provision of a phosphor having a composition of TbAG:Ce, wherein the phosphor having a composition of TbAG:Ce is composed of a compositional formula of (Tbi-xCex)3(Ali_yMy)5Oi2, wherein x is
between 0.01 and 0.4, y is between 0.0 and 0.1, and M is selected from the group consisting of Si and Fe.
In the above formula, if M is Si, y is preferably between 0.01 and 0.04, whereas if M is Fe, y is preferably between 0.01 and 0.02.
In addition, the white photoluminescent device in accordance with the present invention comprises at least one light-emitting diode emitting light with a wavelength of 430 to 470 nm and a phosphor having a composition of TbAG:Ce, wherein the phosphor having a composition of TbAG:Ce is composed of a compositional formula of (Tbi-xCex) 3 (Ali-yMy) 5O12, wherein x is between 0.01 and 0.4, y is between 0.0 and 0.1, and M is selected from the group consisting of Si and Fe.
In the formula, if M is Si, y is preferably between 0.01 and 0.04, whereas if M is Fe, y is preferably between 0.01 and 0.02.
The phosphor in accordance with the present invention is primarily made of Tb and Al as a mother body, and Ce3+ functions as an activator. Where the amount of cerium is less than 0.01, it is not sufficient to serve as the activator. In contrast, where the amount of cerium is greater than 0.4, this may undesirably cause lowering in brightness due to concentration quenching effects.
As raw materials for the phosphor in accordance with the present invention, mention may be made of Tb4θ7, AI2O3 and
CeO2, for example. As an additive, SiO2 or Fe2O3 may be utilized. These materials are quantified within an optimal molar ratio, and are sufficiently mixed to obtain a uniform composition using a mixer. The resulting mixture is placed in a crucible, which is covered with a lid. Then, the mixture is introduced into an electric furnace and calcined by heating the mixture at a temperature of 1400 to 1600° C for 1 to 4 hours. If the calcination temperature is less than 1400° C, single-phase crystals are not completely formed and unreacted reactants or by-products are produced. In addition, if the calcination temperature is above 1600° C, irregularly shaped particles are formed, thus sharply lowering brightness.
Further, fluoride flux may be added to a calcination process. The quantity of fluoride used is preferably in the range of 7 to 15 wt%, relative to (TbI-XCex)S(Al1-YMy)3Oi2. More preferred is 8 wt%. The fluoride utilized in the present invention may include, for example, barium fluoride, ammonium fluoride, sodium fluoride and alumina fluoride. Use of such fluorides in the calcination process enables easy attainment of single-phase phosphors and makes it possible to obtain high-brightness superior phosphors even at low synthesis temperatures.
After completion of the calcination process, the calcined materials are cooled to room temperature and milled in vacuo or under water using a ball mill to obtain powdered
phosphors having a diameter of 0.5 to 20 μm size. The thus- obtained phosphors having a stable phase of (Tbi_xCex)3(AIi- ySiy)3O12 or (Tbi_xCex)3 (Ali_yFey)3O12 are coated on a blue light- emitting diode chip with an emission wavelength near 460 nm made up of GaN or the like. Preferably, 1 to 40 wt% of phosphors are mixed with epoxy resins or silicon based resins and the resulting mixture is coated on the blue LED chip which is then cured at a temperature of 130 to 200° C to fabricate a white light-emitting diode. As such, it is possible to obtain a white light source that achieves high quantum efficiency, desired color temperature (4500K to 8000K) and good color rendering characteristics by use of the single phosphor material in accordance with the present invention alone, and is suited to mass production.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
Fig. 1 is an XRD result of a TAG phosphor in accordance with the present invention;
Fig. 2 is an excitation spectrum of a TAG phosphor in accordance with the present invention;
Fig. 3 is a photoluminescence spectrum of a TAG phosphor in accordance with the present invention; Fig. 4 is a photoluminescence spectrum result of a TAG phosphor based light-emitting diode in accordance with the present invention; and
Fig. 5 is a color coordinate of a TAG phosphor based light-emitting diode in accordance with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following is a comparative analysis of properties of the TAG phosphor and white light-emitting diode prepared according to various examples of the present invention
EXAMPLES
Now, the present invention will be described in more detail with reference to the following Examples. These examples are provided only for illustrating the present invention and should not be construed as limiting the scope and spirit of the present invention.
Example 1
Comparative analysis between the TAG phosphor prepared according to the present invention and a conventional phosphor is given as follows.
Fig. 1 shows the results of X-ray diffraction (XRD) of (Tbo.gCβo.i) 3 (Ali_ySiy) 5O12 phosphors prepared in accordance with the present invention. As can be seen from Fig. 1, the TAG phosphors prepared in accordance with the process of the present invention show formation of a stable garnet structure
(TAG) . Fig. 2 shows an excitation spectrum of (Tb0.9Ce0-I) 3 (AIi- ySiy)5O12 phosphors prepared according to the present invention. Fig. 3 shows comparison between photoluminescence spectra measured under an excitation wavelength of 465 nm, with respect to Si concentrations in (Tbo.gCeo.i)3 (Ali_ySiy) 5O12 phosphors. As can be seen from Fig. 3, the red-band photoluminescence intensity is stronger in phosphors containing Si, as in the present invention, than in conventional TbsAlsO^Ce phosphors.
Table 1 summarizes photoluminescence intensity of Tb3Al5θi2:Ceo.i(sample #0) phosphors prepared according to a conventional method and the (Tb0.9Ce0-I)3(Ali-ySiy)5O12 phosphors prepared according to the present invention measured under an excitation wavelength of 465 nm, based on the molar ratio of Si.
Table 1
PL Intensity|PL increase
Sample #Tb Ce Al Si Remarks (arbitrary)
0.90.11.0 0.000 22.5 lomp. Ex
0.90.10.99750.002522.6
0.90.10.99500.005023.8
0.90.10.99250.007529.0 28.9
4_ 0.90.10.99 0.01 42.0 86.7 5_ 0.90.10.98 0.02 40.0 77.8 6_ 0.90.10.96 0.04 35.0 55.6 7_ 0.90.10.94 0.06 31.0 37.7 8_ 0.90.10.92 0.08 27.5 22.2 9 0.90.10.90 0.1 23.8 5.8
Photoluminescence intensity (PL) was remarkably excellent in the range of 0.01 to 0.04 of the Si molar ratio. In particular, when the Si molar ratio was 0.01, it showed about 87% improvement in PL, as compared to a comparative example.
Table 2 summarizes photoluminescence intensity of Tb3Al5Oi2:Ceo.i (sample #0) phosphors prepared according to a conventional method and the (Tb0.9Ce0.i) 3(Ali-yFey) 5Oi2 phosphors prepared according to the present invention measured under an
excitation wavelength of 465 run, based on the molar ratio of Fe.
Table 2
As can be seen from table 2, photoluminescence intensity was remarkably excellent in the range of 0.01 to 0.02 of the Fe molar ratio. When the Fe molar ratio was 0.01, it showed about 51% improvement in photoluminescence intensity, as compared to a comparative example. Fe has lower excitation intensity than Si, but the phosphors having a Fe molar ratio
of 0.01 mol exhibited better results than the comparative example.
Example 2
The following evaluation results illustrate properties of a white LED prepared by applying a mixture of the TAG phosphor prepared according to the present invention and a light-transmissive silicon resin to a 460 nm (In)GaN blue light-emitting diode chip, followed by curing and drying.
Table 3 summarizes characteristics of Tb3Al5θi2:Ceo.i (sample #0) phosphors prepared according to a conventional method and the (Tbo.gCeo.i)3(Ali-.ySiy) 5O12 phosphors with replacement of Si content with the range of 0.0 < y < 0.1, prepared according to the present invention, on the basis of the molar ratio.
Table 3
23 0.90.10.98 0.02 2.35 43.3 95.24
24 0.90.10.96 .04 2.19 33.5 94.56
25 0.90.10.94 0.06 1.98 20.7 94.60
26 0.90.10.92 0.08 1.85 12.8 93.81
27 0.90.10.90 .1 1.70 3.7 93.00
Reliability data is a proportion of sample with characteristics equal to or higher than given criteria, after heat treatment at 85° C for 500 hours. At a Si molar ratio of 0.01 to 0.04, remarkably excellent results were obtained, ;as compared to the conventional art. In particular, when the Si molar ratio was 0.01, brightness increased by 47% and reliability was improved to 97.7%.
Fig. 4 is a photoluminescence spectrum result of a light-emitting diode fabricated using (Tbo.gCeo.i)3(Alo.99Sio.o1) 5O12 phosphors prepared according to the present invention.
Table 4 summarizes characteristics of Tb3Al5Oi2:Ceo.1 (sample #0) phosphors prepared according to a conventional method and the (Tbo.gCeo.i)3(Ali_yFey)5O12 with replacement of Fe content with the range of 0.0 < y < 0.1, prepared according to the present invention, on the basis of molar ratio.
Table 4
Reliability data is a proportion of sample with characteristics equal to or higher than given criteria, after heat treatment at 85° C for 500 hours. The Fe molar ratio of 0.01 to 0.02 exhibited remarkably excellent results, as compared to the conventional art. In particular, when the Fe molar ratio was 0.01, brightness increased by 37% and reliability was improved to 95.2%.
Fig. 5 shows the measured result of a CIE (Commission international de l'Eclairage) color coordinate (X, Y) on a photoluminescence spectrum of a light-emitting diode fabricated using a TAG phosphor in accordance with the present invention. As can be seen from Fig. 5, X and Y coordinates exhibited excellent color rendering within the range of pure white color, high brightness and excellent reliability.
The white LED fabricated using (Tbo.gCeo.i) 3 (Alo.95Sio.o5) 5O12 phosphors had a chromaticity point
XY= (0.298, 0.32) , and photoluminescence efficiency of 1.77 ml/w. In addition, the white LED fabricated using
(Tbo.95Ceo.o5)3 (Alo.99Feo.o1)5O12 phosphors had a chromaticity point
XY=(0.31, 0.29) , and photoluminescence efficiency of 1.779 ml/w.
As apparent from the above description, in accordance with the present invention, it is possible to obtain a white LED having high brightness and excellent color rendering characteristics. Further, it is possible to obtain a TAG based white LED having strong photoluminescence intensity in a red light region and excellent chip color characteristics.
Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible,
without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
Claims
1. A phosphor having a composition of TbAG:Ce, wherein the phosphor having a composition of TbAG:Ce is composed of a compositional formula of (Tbi-xCex)3(Ali_yFey) 5O12, wherein x is between 0.01 and 0.4, and y is between 0.0 and 0.1.
2. A phosphor having a composition of TbAG:Ce, wherein the phosphor having a composition of TbAG:Ce is composed of a compositional formula of (Tbi-xCex)3 (Ali_ySiy) 5O12, wherein x is between 0.01 and 0.4, and y is between 0.01 and 0.04.
3. The phosphor according to claim 1, wherein, in the compositional formula, y is between 0.01 and 0.02.
4. A white photoluminescent device comprising at least one light-emitting diode emitting light with a wavelength of 430 to 470 nm and a phosphor having a composition of TbAG:Ce, wherein the phosphor having a composition of TbAG:Ce is composed of a compositional formula of (Tbi-xCex) 3 (Ali_yFey)5O12, wherein x is between 0.01 and 0.4, and y is between 0.0 and 0.1.
5. A white photoluminescent device comprising at least one light-emitting diode emitting light with a wavelength of 430 to 470 nm and a phosphor having a composition of TbAG:Ce, wherein the phosphor having a composition of TbAG:Ce is composed of a compositional formula of (Tbi-xCex) 3 (Ali_ySiy)5O12, wherein x is between 0.01 and 0.4, and y is between 0.01 and 0.04.
6. The white photoluminescent device according to claim 4, wherein, in the compositional formula, y is between 0.01 and 0.02.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP05738295A EP1849192B1 (en) | 2004-10-11 | 2005-04-12 | White light emitting device |
| US11/575,504 US7591963B2 (en) | 2004-10-11 | 2005-04-12 | White light emitting device |
| JP2007535594A JP4098354B2 (en) | 2004-10-11 | 2005-04-12 | White light emitting device |
| AT05738295T ATE514197T1 (en) | 2004-10-11 | 2005-04-12 | WHITE LIGHT EMITTING COMPONENT |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR10-2004-0080982 | 2004-10-11 | ||
| KR1020040080982A KR100485673B1 (en) | 2004-10-11 | 2004-10-11 | White photoluminescence device |
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| Publication Number | Publication Date |
|---|---|
| WO2006041249A1 true WO2006041249A1 (en) | 2006-04-20 |
Family
ID=36148525
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/KR2005/001046 WO2006041249A1 (en) | 2004-10-11 | 2005-04-12 | White light emitting device |
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|---|---|
| US (1) | US7591963B2 (en) |
| EP (1) | EP1849192B1 (en) |
| JP (1) | JP4098354B2 (en) |
| KR (1) | KR100485673B1 (en) |
| AT (1) | ATE514197T1 (en) |
| TW (1) | TWI284427B (en) |
| WO (1) | WO2006041249A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010509414A (en) * | 2006-11-13 | 2010-03-25 | ジェネラル リサーチ インスティテュート フォア ノンフェラス メタルス ベイジン | Aluminate phosphor containing divalent metal element, production method thereof, and light-emitting device incorporating the phosphor |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7918582B2 (en) * | 2005-12-30 | 2011-04-05 | Dialight Corporation | Signal light using phosphor coated LEDs |
| WO2007079423A2 (en) | 2005-12-30 | 2007-07-12 | Dialight Corporation | Method and apparatus for providing a light source that combines different color leds |
| TWI437077B (en) * | 2011-12-08 | 2014-05-11 | Univ Nat Cheng Kung | Yttrium aluminum garnet phosphor, method for preparing the same, and light-emitting diode containing the same |
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| US4755715A (en) * | 1986-02-28 | 1988-07-05 | American Telephone & Telegraph Company, At&T Bell Laboratories | Pr:tb activated phosphor for use in CRTS |
| JP2003535478A (en) * | 2000-05-29 | 2003-11-25 | パテント−トロイハント−ゲゼルシヤフト フユール エレクトリツシエ グリユーラムペン ミツト ベシユレンクテル ハフツング | LED based white light emitting lighting unit |
| JP2004115304A (en) * | 2002-09-25 | 2004-04-15 | Matsushita Electric Ind Co Ltd | Inorganic oxide and phosphor, and light emitting apparatus using the same |
| JP2004250705A (en) * | 2003-02-20 | 2004-09-09 | Osram Opto Semiconductors Gmbh | Covered luminescent substance, light-emitting device containing the luminescent substance and method for manufacturing the luminescent substance |
| KR200364708Y1 (en) * | 2004-06-14 | 2004-10-12 | 하바텍 코포레이션 | White light emitting diode light source |
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| TW383508B (en) | 1996-07-29 | 2000-03-01 | Nichia Kagaku Kogyo Kk | Light emitting device and display |
| DE59814117D1 (en) | 1997-03-03 | 2007-12-20 | Philips Intellectual Property | WHITE LUMINESCENCE DIODE |
| JPH11278980A (en) * | 1998-03-25 | 1999-10-12 | Murata Mfg Co Ltd | Growth of single crystal |
| WO2001008452A1 (en) * | 1999-07-23 | 2001-02-01 | Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH | Luminous substance for a light source and light source associated therewith |
| US6596195B2 (en) * | 2001-06-01 | 2003-07-22 | General Electric Company | Broad-spectrum terbium-containing garnet phosphors and white-light sources incorporating the same |
| US6869753B2 (en) * | 2002-10-11 | 2005-03-22 | Agilent Technologies, Inc. | Screen printing process for light emitting base layer |
| TWI229125B (en) * | 2003-03-28 | 2005-03-11 | Nantex Industry Co Ltd | Fluorescent material of terbium aluminum garnet and manufacturing method therefor |
| DE10360546A1 (en) * | 2003-12-22 | 2005-07-14 | Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH | Phosphor and light source with such phosphor |
-
2004
- 2004-10-11 KR KR1020040080982A patent/KR100485673B1/en active IP Right Grant
-
2005
- 2005-04-12 AT AT05738295T patent/ATE514197T1/en not_active IP Right Cessation
- 2005-04-12 JP JP2007535594A patent/JP4098354B2/en not_active Expired - Fee Related
- 2005-04-12 WO PCT/KR2005/001046 patent/WO2006041249A1/en active Application Filing
- 2005-04-12 EP EP05738295A patent/EP1849192B1/en not_active Not-in-force
- 2005-04-12 US US11/575,504 patent/US7591963B2/en active Active
- 2005-04-28 TW TW094113697A patent/TWI284427B/en not_active IP Right Cessation
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4755715A (en) * | 1986-02-28 | 1988-07-05 | American Telephone & Telegraph Company, At&T Bell Laboratories | Pr:tb activated phosphor for use in CRTS |
| JP2003535478A (en) * | 2000-05-29 | 2003-11-25 | パテント−トロイハント−ゲゼルシヤフト フユール エレクトリツシエ グリユーラムペン ミツト ベシユレンクテル ハフツング | LED based white light emitting lighting unit |
| JP2004115304A (en) * | 2002-09-25 | 2004-04-15 | Matsushita Electric Ind Co Ltd | Inorganic oxide and phosphor, and light emitting apparatus using the same |
| JP2004250705A (en) * | 2003-02-20 | 2004-09-09 | Osram Opto Semiconductors Gmbh | Covered luminescent substance, light-emitting device containing the luminescent substance and method for manufacturing the luminescent substance |
| KR200364708Y1 (en) * | 2004-06-14 | 2004-10-12 | 하바텍 코포레이션 | White light emitting diode light source |
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| JP2010509414A (en) * | 2006-11-13 | 2010-03-25 | ジェネラル リサーチ インスティテュート フォア ノンフェラス メタルス ベイジン | Aluminate phosphor containing divalent metal element, production method thereof, and light-emitting device incorporating the phosphor |
Also Published As
| Publication number | Publication date |
|---|---|
| TWI284427B (en) | 2007-07-21 |
| TW200612580A (en) | 2006-04-16 |
| US7591963B2 (en) | 2009-09-22 |
| ATE514197T1 (en) | 2011-07-15 |
| US20080197320A1 (en) | 2008-08-21 |
| EP1849192B1 (en) | 2011-06-22 |
| EP1849192A1 (en) | 2007-10-31 |
| EP1849192A4 (en) | 2010-01-06 |
| JP2008516042A (en) | 2008-05-15 |
| JP4098354B2 (en) | 2008-06-11 |
| KR100485673B1 (en) | 2005-04-27 |
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