Browsing by Author "Kuo, Te-Wen"

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A Green-Emitting Phosphor Sr(3)La(PO(4))(3):Ce(3+),Tb(3+) with Efficient Energy Transfer for Fluorescent Lamp
(2010-01-01)
Kuo, Te-Wen
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
Green-emitting phosphors of Sr(3)La(PO(4))(3):Ce(3+),Tb(3+) have been synthesized by a solid-state reaction. The energy transfer from Ce(3+) to Tb(3+) is a resonant type via a dipole-dipole mechanism with an energy-transfer critical distance of 7.6 angstrom. By utilizing the principle of energy transfer and appropriate tuning of activator contents, we have also made an attempt to observe a strong green emission performance displayed by this phosphor for use as a coating material on compact fluorescent lamps (CFLs). The results clearly indicate that the luminous efficiency based on Sr(3)(La(0.67)Ce(0.08)Tb(0.25))(PO(4))(3) was found to be 69 lm/W. The good luminous efficiency and lumen maintenance (2000 h, 91.8%) of the green-emitting CFL demonstrate that this phosphor can be suitable for application on a short UV fluorescent lamp. Additionally, the Sr(3)(La(0.67)Ce(0.08)Tb(0.25))(PO(4))(3) green phosphor has advantages of environmental friendliness and low cost. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3384662] All rights reserved.
A Green-Emitting Phosphor Sr3La(PO4)(3):Ce3+,Tb3+ with Efficient Energy Transfer for Fluorescent Lamp
(2010-01-01)
Kuo, Te-Wen
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
Green-emitting phosphors of Sr3La(PO4)(3):Ce3+,Tb3+ have been synthesized by a solid-state reaction. The energy transfer from Ce3+ to Tb3+ is a resonant type via a dipole-dipole mechanism with an energy-transfer critical distance of 7.6 angstrom. By utilizing the principle of energy transfer and appropriate tuning of activator contents, we have also made an attempt to observe a strong green emission performance displayed by this phosphor for use as a coating material on compact fluorescent lamps (CFLs). The results clearly indicate that the luminous efficiency based on Sr-3(La0.67Ce0.08Tb0.25)(PO4)(3) was found to be 69 lm/W. The good luminous efficiency and lumen maintenance (2000 h, 91.8%) of the green-emitting CFL demonstrate that this phosphor can be suitable for application on a short UV fluorescent lamp. Additionally, the Sr-3(La0.67Ce0.08Tb0.25)(PO4)(3) green phosphor has advantages of environmental friendliness and low cost. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3384662] All rights reserved.
Deep Red Emission of Ca(19)Ce(PO(4))(14):Mn(2+) Phosphor for Fluorescent Lamp and PDP Applications
(2010-03-05)
Kuo, Te-Wen
;
Chung, Hsiu-Pei
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
The unprecedented deep red-emitting phosphor, Ca(19)Ce(PO(4))(14):Mn(2+), has been fabricated by a convenient solid-state method. A strong red emission centered at 637 nm corresponding to the 4T1(4G) -> 6A1(6S) transition of Mn(2+) is observed under 130-300 nm excitation. The chromaticity coordinates of optimized phosphor were found to be (0.69, 0.29). In addition, we have also made an attempt to observe strong red emission displayed by this phosphor for use as coating material on compact fluorescent lamps (CFLs). It is a promising candidate for application in CFLs as a red-emitting color converter.
Deep Red Emission of Ca19Ce(PO4)(14):Mn2+ Phosphor for Fluorescent Lamp and PDP Applications
(2010-03-05)
Kuo, Te-Wen
;
Chung, Hsiu-Pei
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
The unprecedented deep red-emitting phosphor, Ca19Ce(PO4)(14):Mn2+, has been fabricated by a convenient solid-state method. A strong red emission centered at 637 nm corresponding to the 4T1(4G) -> 6A1(6S) transition of Mn2+ is observed under 130-300 nm excitation. The chromaticity coordinates of optimized phosphor were found to be (0.69, 0.29). In addition, we have also made an attempt to observe strong red emission displayed by this phosphor for use as coating material on compact fluorescent lamps (CFLs). It is a promising candidate for application in CFLs as a red-emitting color converter.
Emission color variation of (Ba,Sr)(3)BP(3)O(12):Eu(2+) phosphors for white light LEDs
(2010-02-01)
Kuo, Te-Wen
;
Liu, Wei-Ren
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
A series of alkaline earth borophosphate phosphors, (Ba,Sr)(3)BP(3)O(12) doped with Eu(2+) ions, were synthesized by a solid state reaction. Two emission bands at 465 nm and 520 nm were attributed to the f-d transitions of doped Eu(2+) ions occupying in two different cation sites in host lattices and emission color variation was observed by substituting the M(2+) sites, which was rationalized in terms of two competing factors of the crystal field strength and bond covalence. Green and bluish-white pc-LEDs were fabricated by combination of a 370 nm near-UV chip and composition-optimized Ba(3)BP(3)O(12):Eu(2+) and (Ba,Sr)(3)BP(3)O(12):Eu(2+) phosphors, respectively. The series of phosphors may serve as a promising green and bluish-white luminescent materials used in fabrication of near UV-based white pc-LEDs. (C) 2010 Optical Society of America
Emission color variation of (Ba,Sr)(3)BP3O12:Eu2+ phosphors for white light LEDs
(2010-02-01)
Kuo, Te-Wen
;
Liu, Wei-Ren
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
A series of alkaline earth borophosphate phosphors, (Ba,Sr)(3)BP3O12 doped with Eu2+ ions, were synthesized by a solid state reaction. Two emission bands at 465 nm and 520 nm were attributed to the f-d transitions of doped Eu2+ ions occupying in two different cation sites in host lattices and emission color variation was observed by substituting the M2+ sites, which was rationalized in terms of two competing factors of the crystal field strength and bond covalence. Green and bluish-white pc-LEDs were fabricated by combination of a 370 nm near-UV chip and composition-optimized Ba3BP3O12:Eu2+ and (Ba,Sr)(3)BP3O12:Eu2+ phosphors, respectively. The series of phosphors may serve as a promising green and bluish-white luminescent materials used in fabrication of near UV-based white pc-LEDs. (C) 2010 Optical Society of America
High color rendering white light-emitting-diode illuminator using the red-emitting Eu(2+)-activated CaZnOS phosphors excited by blue LED
(2010-04-12)
Kuo, Te-Wen
;
Liu, Wei-Ren
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
A red phosphor CaZnOS:Eu(2+) was synthesized by solid state reaction and has been evaluated as a candidate for white LEDs. For this material, the XRD, PL, PL excitation (PLE) and diffuse reflection spectra have also been investigated. CaZnOS:Eu(2+) reveals a broad absorption band and good color purity. By utilizing a mixture of red-emitting CaZnOS:Eu(2+), green-emitting (Ba,Sr)(2)SiO(4):Eu(2+) and yellow-emitting Y(3)Al(5)O(12):Ce(3+) as light converters, an intense white InGaN-based blue-LED (similar to 460 nm) was fabricated to exhibit a high color-rendering index Ra of 85 at a correlated color temperature of 4870 K. Based on the results, we are currently evaluating the potential application of CaZnOS:Eu(2+) as a red-emitting blue-chip convertible phosphor. (c) 2010 Optical Society of America
High color rendering white light-emitting-diode illuminator using the red-emitting Eu2+-activated CaZnOS phosphors excited by blue LED
(2010-04-12)
Kuo, Te-Wen
;
Liu, Wei-Ren
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
A red phosphor CaZnOS:Eu2+ was synthesized by solid state reaction and has been evaluated as a candidate for white LEDs. For this material, the XRD, PL, PL excitation (PLE) and diffuse reflection spectra have also been investigated. CaZnOS:Eu2+ reveals a broad absorption band and good color purity. By utilizing a mixture of red-emitting CaZnOS:Eu2+, green-emitting (Ba,Sr)(2)SiO4:Eu2+ and yellow-emitting Y3Al5O12:Ce3+ as light converters, an intense white InGaN-based blue-LED (similar to 460 nm) was fabricated to exhibit a high color-rendering index Ra of 85 at a correlated color temperature of 4870 K. Based on the results, we are currently evaluating the potential application of CaZnOS:Eu2+ as a red-emitting blue-chip convertible phosphor. (c) 2010 Optical Society of America
Intense violet-blue-emitting Ba(2)AlB(4)O(9)Cl:Eu(2+) phosphors for applications in fluorescent lamps and ultraviolet-light-emitting diodes
(2010-08-01)
Kuo, Te-Wen
;
Huang, Chien-Hao
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
We synthesized a violet-blue phosphor Ba(2)AlB(4)O(9)Cl:Eu(2+) with a solid-state reaction. The excitation and emission spectra of this phosphor showed that all were broadband due to 4f(7) - 4f(6)d(1) transitions of Eu(2+). The phosphors with different Eu(2+) concentrations presented violet-blue luminescence for ultraviolet [(UV) 250-390 nm] excitation. The optimum concentration of Eu(2+) in Ba(2)AlB(4)O(9)Cl:Eu(2+) is determined to be 6 mol.%. The luminous efficiency was found to be 8.1 lm/W for the violet-blue fluorescent lamp and 3.2 lm/W for the violet-blue phosphor-converted light-emitting diode, respectively. Ba(2)AlB(4)O(9)Cl:Eu(2+) would be a promising phosphor for converting the UV radiation to violet-blue emission for a novel high light-conversion efficiency phototherapy illuminator. (C) 2010 Optical Society of America
Intense violet-blue-emitting Ba2AlB4O9Cl:Eu2+ phosphors for applications in fluorescent lamps and ultraviolet-light-emitting diodes
(2010-08-01)
Kuo, Te-Wen
;
Huang, Chien-Hao
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
We synthesized a violet-blue phosphor Ba2AlB4O9Cl:Eu2+ with a solid-state reaction. The excitation and emission spectra of this phosphor showed that all were broadband due to 4f(7) - 4f(6)d(1) transitions of Eu2+. The phosphors with different Eu2+ concentrations presented violet-blue luminescence for ultraviolet [(UV) 250-390 nm] excitation. The optimum concentration of Eu2+ in Ba2AlB4O9Cl:Eu2+ is determined to be 6 mol.%. The luminous efficiency was found to be 8.1 lm/W for the violet-blue fluorescent lamp and 3.2 lm/W for the violet-blue phosphor-converted light-emitting diode, respectively. Ba2AlB4O9Cl:Eu2+ would be a promising phosphor for converting the UV radiation to violet-blue emission for a novel high light-conversion efficiency phototherapy illuminator. (C) 2010 Optical Society of America
Novel green-emitting Na(2)CaPO(4)F:Eu(2+) phosphors for near-ultraviolet white light-emitting diodes
(2011-07-01)
Huang, Chien-Hao
;
Chen, Yen-Chi
;
Kuo, Te-Wen
;
Chen, Teng-Ming
;
應用化學系
In this study, green-emitting Na(2)CaPO(4)F:Eu(2+) phosphors were synthesized by solid-state reactions. The excitation spectra of the phosphors showed a broad hump between 250 and 450 nm; the spectra match well with the near-ultraviolet (NUV) emission spectra of light-emitting diodes (LEDs). The emission spectrum showed an intense broad emission band centered at 506 nm. White LEDs were fabricated by integrating a 390 nm NUV chip comprising blue-emitting BaMgAl(10)O(17):Eu(2+), green-emitting Na(2)CaPO(4)F:0.02 Eu(2+), and red-emitting CaAlSiN(3):Eu(2+) phosphors into a single package; the white LEDs exhibited white light with a correlated color temperature of 5540 K. a color-rendering index of 90.75, and color coordinates (0.332, 0.365) close to those of ideal white light. (C) 2011 Elsevier B.V. All rights reserved.
Novel green-emitting Na2CaPO4F:Eu2+ phosphors for near-ultraviolet white light-emitting diodes
(2011-07-01)
Huang, Chien-Hao
;
Chen, Yen-Chi
;
Kuo, Te-Wen
;
Chen, Teng-Ming
;
應用化學系
In this study, green-emitting Na2CaPO4F:Eu2+ phosphors were synthesized by solid-state reactions. The excitation spectra of the phosphors showed a broad hump between 250 and 450 nm; the spectra match well with the near-ultraviolet (NUV) emission spectra of light-emitting diodes (LEDs). The emission spectrum showed an intense broad emission band centered at 506 nm. White LEDs were fabricated by integrating a 390 nm NUV chip comprising blue-emitting BaMgAl10O17:Eu2+, green-emitting Na2CaPO4F:0.02 Eu2+, and red-emitting CaAlSiN3:Eu2+ phosphors into a single package; the white LEDs exhibited white light with a correlated color temperature of 5540 K. a color-rendering index of 90.75, and color coordinates (0.332, 0.365) close to those of ideal white light. (C) 2011 Elsevier B.V. All rights reserved.
Novel Red-Emitting Phosphor Ca(9)Y(PO(4))(7):Ce(3+),Mn(2+) with Energy Transfer for Fluorescent Lamp Application
(2010-05-01)
Huang, Chien-Hao
;
Kuo, Te-Wen
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
A series of new luminescent emission-tunable phosphors Ca(9)Y(PO(4))(7):zCe(3+),xMn(2+) have been synthesized by a high-temperature solid-state reaction. We report a broad deep red-emitting composition-optimized phosphor (Ca(0.9))(9)Y(0.85)(PO(4))(7): 0.15Ce(3+),0.1Mn(2+), which has been found to be feasible for the application in fluorescent lamps. The Commission Internationale de l'Eclairage (CIE) chromaticity coordinates measured for the phosphor were (0.68, 0.29), and those for fluorescent lamps with and without a 600 nm filter were found to be (0.67, 0.29) and (0.54, 0.32), respectively.,The Ca(9)Y(PO(4))(7):Ce(3+),Mn(2+) phosphor showed two emission band's under 254 nm excitation: the one observed at 366 nm was attributed to Ce(3+) ion emission, and the other found at 650 nm was assigned to the emission from Mn(2+) ions. We have shown that the mechanism of energy transfer from Ce(3+) to Mn(2+) was of the resonance type and it occurred via an electric dipole-quadrupole interaction. Furthermore, we have calculated the critical distance for Ce(3+) -> Mn(2+) energy transfer to be 13.45 angstrom by concentration quenching methods.
Novel Red-Emitting Phosphor Ca9Y(PO4)(7):Ce3+,Mn2+ with Energy Transfer for Fluorescent Lamp Application
(2010-05-01)
Huang, Chien-Hao
;
Kuo, Te-Wen
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
A series of new luminescent emission-tunable phosphors Ca9Y(PO4)(7):zCe(3+),xMn(2+) have been synthesized by a high-temperature solid-state reaction. We report a broad deep red-emitting composition-optimized phosphor (Ca-0.9)(9)Y-0.85(PO4)(7): 0.15Ce(3+),0.1Mn(2+), which has been found to be feasible for the application in fluorescent lamps. The Commission Internationale de l'Eclairage (CIE) chromaticity coordinates measured for the phosphor were (0.68, 0.29), and those for fluorescent lamps with and without a 600 nm filter were found to be (0.67, 0.29) and (0.54, 0.32), respectively.,The Ca9Y(PO4)(7):Ce3+,Mn2+ phosphor showed two emission band's under 254 nm excitation: the one observed at 366 nm was attributed to Ce3+ ion emission, and the other found at 650 nm was assigned to the emission from Mn2+ ions. We have shown that the mechanism of energy transfer from Ce3+ to Mn2+ was of the resonance type and it occurred via an electric dipole-quadrupole interaction. Furthermore, we have calculated the critical distance for Ce3+ -> Mn2+ energy transfer to be 13.45 angstrom by concentration quenching methods.
Novel yellowish-orange Sr(8)Al(12)O(24)S(2):Eu(2+) phosphor for application in blue light-emitting diode based white LED
(2010-06-21)
Kuo, Te-Wen
;
Huang, Chien-Hao
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
A new yellowish-orange phosphor, Sr(8)Al(12)O(24)S(2):Eu(2+), was synthesized by the solid-state method and its photoluminescence properties were investigated by excitation and emission spectra. Its excitation band is extending from 400-500 nm, which is adaptable to the emission band of blue LED chips (450-470 nm). Upon the excitation of 450 nm light, the phosphor exhibits strong yellowish-orange emission centered at 605 nm with good thermal stability. A white light-emitting diode (W-LED) that consists of a blue LED chip (similar to 470 nm) and a (Sr(0.92)Eu(0.08))(8)Al(12)O(24)S(2) phosphor is demonstrated. The CIE 1931 chromaticity coordinates (x, y) are (0.34, 0.25), the correlated color temperature (CCT) is 4300 K, and the luminous efficacy of this W-LED is 14.2 1m/W at room temperature and with a forward-bias current of 400 mA. (C) 2010 Optical Society of America
Novel yellowish-orange Sr8Al12O24S2:Eu2+ phosphor for application in blue light-emitting diode based white LED
(2010-06-21)
Kuo, Te-Wen
;
Huang, Chien-Hao
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
A new yellowish-orange phosphor, Sr8Al12O24S2:Eu2+, was synthesized by the solid-state method and its photoluminescence properties were investigated by excitation and emission spectra. Its excitation band is extending from 400-500 nm, which is adaptable to the emission band of blue LED chips (450-470 nm). Upon the excitation of 450 nm light, the phosphor exhibits strong yellowish-orange emission centered at 605 nm with good thermal stability. A white light-emitting diode (W-LED) that consists of a blue LED chip (similar to 470 nm) and a (Sr0.92Eu0.08)(8)Al12O24S2 phosphor is demonstrated. The CIE 1931 chromaticity coordinates (x, y) are (0.34, 0.25), the correlated color temperature (CCT) is 4300 K, and the luminous efficacy of this W-LED is 14.2 1m/W at room temperature and with a forward-bias current of 400 mA. (C) 2010 Optical Society of America
Preparation and Luminescence of Novel Oxysulfide Phosphors for White Light LEDs
(2010)
Chen, Teng-Ming
;
Kuo, Te-Wen
;
應用化學系
;
Department of Applied Chemistry
Two unprecedented phosphors, CaZnOS:Eu2+ and Sr8Al12O24S2:Eu2+, were prepared and investigated. The PL spectra of both reveal a broad emission band extending from 550 to 700 nm under blue light pumping Both phosphors exhibit superior stability than SrS:Eu2+ in thermal quenching up to 120 degrees C and great potential for LED application.
Synthesis and luminescence of Ca(4)YO(BO(3))(3):Eu(3+) for fluorescent lamp application
(2010-07-01)
Kuo, Te-Wen
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
The red-emitting Ca(4)YO(BO(3))(3):Eu(3+) phosphor has been prepared at 1200 degrees C by the simple solid-state reaction. This preparation temperature is much lower than Y(2)O(3):Eu(3+) (1400-1500 degrees C) for conventional solid-state reaction method. In particular, the complete process to produce high-quality phosphor particles was carried out through the single-step heat treatment of the mixture of corresponding oxide-type metal sources. For this material, the XRD, PL, PL excitation (PLE) and SEM features have also been investigated. The X-ray diffraction data indicate that pure phase of Ca(4)YO(BO(3))(3):Eu(3+) can be successfully obtained. Among the different emission transitions (5)D(0) -> (7)F(J=0. 1. 2. 3. 4) of this phosphor, one particular transition ((5)D(0) -> (7)F(2)) at 610 nm has been found. Besides carrying out these essential measurements, we have also made an attempt to observe a strong red emission performance displayed by this phosphor for use as coating material on compact fluorescent lamps (CFLs). The results clearly indicate that the life time based on Ca(4)YO(BO(3))(3):Eu(3+) was found to be much longer than that using Y(2)O(3):Eu(3+). The good performances of the CFLs demonstrate that this phosphor may be suitable for application on short ultraviolet fluorescent lamp. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.
Synthesis and luminescence of Ca4YO(BO3)(3):Eu3+ for fluorescent lamp application
(2010-07-01)
Kuo, Te-Wen
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
The red-emitting Ca4YO(BO3)(3):Eu3+ phosphor has been prepared at 1200 degrees C by the simple solid-state reaction. This preparation temperature is much lower than Y2O3:Eu3+ (1400-1500 degrees C) for conventional solid-state reaction method. In particular, the complete process to produce high-quality phosphor particles was carried out through the single-step heat treatment of the mixture of corresponding oxide-type metal sources. For this material, the XRD, PL, PL excitation (PLE) and SEM features have also been investigated. The X-ray diffraction data indicate that pure phase of Ca4YO(BO3)(3):Eu3+ can be successfully obtained. Among the different emission transitions D-5(0) -> F-7(J=0. 1. 2. 3. 4) of this phosphor, one particular transition (D-5(0) -> F-7(2)) at 610 nm has been found. Besides carrying out these essential measurements, we have also made an attempt to observe a strong red emission performance displayed by this phosphor for use as coating material on compact fluorescent lamps (CFLs). The results clearly indicate that the life time based on Ca4YO(BO3)(3):Eu3+ was found to be much longer than that using Y2O3:Eu3+. The good performances of the CFLs demonstrate that this phosphor may be suitable for application on short ultraviolet fluorescent lamp. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.
Synthesis and luminescence properties of Eu(3+), Ce(3+) and Tb(3+)-activated Sr(3)La(2)(BO(3))(4) under UV excitation
(2010-03-01)
Kuo, Te-Wen
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
The spectroscopic properties in UV-excitable range for the phosphors of Sr(3)La(2)(BO(3))(4):RE(3+) (RE(3+) = Eu(3+), Ce(3+), Tb(3+)) were investigated. The phosphors were synthesized by conventional solid-state reactions. The photoluminescence (PL) spectra and commission international de l'Eclairage (CIE) coordinates of Sr3La2(BO3)4:RE 31 were investigated. The f-d transitions of Eu(3+), Ce(3+) and Tb(3+) in the host lattices are assumed and corroborated. The PL and PL excitation (PLE) spectra indicate that the main emission wavelength of Sr(3)La(2)(BO(3))(4):Eu(3+) is 611 nm, and Sr(3)La(2)(BO(3))(4):Ce(3+) shows dominating emission peak at 425 nm, while Sr(3)La(2)(BO(3))(4):Tb(3+) displays green emission at 487, 542, 582 and 620 nm. These phosphors were prepared by simple solid-state reaction at 1000 degrees C. There are lower reactive temperature and more convenient than commercial phosphors. The Sr(3)La(2)(BO(3))(4):Tb(3+) applied to cold cathode fluorescent lamp was found to emit green light and have a major peak wavelength at around 542 nm. These phosphors may provide a new kind of luminescent materials under ultraviolet excitation. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.