Browsing by Author "Chang, Chun-Kuei"

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Ca(2)PO(4)Cl : Eu(2+): an intense near-ultraviolet converting blue phosphor for white light-emitting diodes
(2010-01-01)
Chiu, Yi-Chen
;
Liu, Wei-Ren
;
Chang, Chun-Kuei
;
Liao, Cheng-Chun
;
Yeh, Yao-Tsung
A blue phosphor Ca(2)PO(4)Cl : Eu(2+) was synthesized by solid state reaction and evaluated as a candidate for white LEDs. The luminescent intensity of Ca(2)PO(4)Cl : Eu(2+) was found to be 128% under excitation at 380 nm, 149% under 400 nm, and 247% under 420 nm, as high as that of BaMgAl(10)O(17) : Eu(2+). Furthermore, Ca(2)PO(4)Cl : Eu(2+) reveals high quantum efficiency and excellent thermal stability. By utilizing a mixture of blue-emitting Ca(2)PO(4)Cl : Eu(2+), green-emitting (Ba, Sr)(2)SiO(4) : Eu(2+) and redemitting CaAlSiN(3) : Eu(2+) as light converters, an intense white GaN-based n-UV-LED (400 nm) was fabricated to exhibit an excellent color-rendering index R(a) of 93.4 at a correlated color temperature of 4590 K. Based on the results, we are currently evaluating the potential application of Ca(2)PO(4)Cl : Eu(2+) as a blue-emitting near-UV convertible phosphor.
Ca2PO4Cl : Eu2+: an intense near-ultraviolet converting blue phosphor for white light-emitting diodes
(2010-01-01)
Chiu, Yi-Chen
;
Liu, Wei-Ren
;
Chang, Chun-Kuei
;
Liao, Cheng-Chun
;
Yeh, Yao-Tsung
A blue phosphor Ca2PO4Cl : Eu2+ was synthesized by solid state reaction and evaluated as a candidate for white LEDs. The luminescent intensity of Ca2PO4Cl : Eu2+ was found to be 128% under excitation at 380 nm, 149% under 400 nm, and 247% under 420 nm, as high as that of BaMgAl10O17 : Eu2+. Furthermore, Ca2PO4Cl : Eu2+ reveals high quantum efficiency and excellent thermal stability. By utilizing a mixture of blue-emitting Ca2PO4Cl : Eu2+, green-emitting (Ba, Sr)(2)SiO4 : Eu2+ and redemitting CaAlSiN3 : Eu2+ as light converters, an intense white GaN-based n-UV-LED (400 nm) was fabricated to exhibit an excellent color-rendering index R-a of 93.4 at a correlated color temperature of 4590 K. Based on the results, we are currently evaluating the potential application of Ca2PO4Cl : Eu2+ as a blue-emitting near-UV convertible phosphor.
Intense blue-emitting Ca(2)PO(4)Cl:Eu(2+) phosphor for near-ultraviolet converting white light-emitting diodes
(2010-12-01)
Chiu, Yi-Chen
;
Liu, Wei-Ren
;
Chang, Chun-Kuei
;
Liao, Cheng-Chun
;
Yeh, Yao-Tsung
A blue phosphor Ca(2)PO(4)Cl:Eu(2+) (CAP:Eu(2+)) was synthesized by solid state reaction. The Ca(2)PO(4)Cl:Eu(2+) exhibited high quantum efficiency and excellent thermal stability. The luminescent intensity of Ca(2)PO(4)Cl:Eu(2+) was found to be 128% under excitation at 380 nm, 149% under 400 nm, and 247% under 420 nm as high as that of BaMgAl(10)O(17):Eu(2+). The optimal doping concentration was observed to 11 mol.% of CAP:Eu(2+). The energy transfer between Eu(2+) ions in CAP were occurred via electric multipolar interaction, and the critical transfer distance was estimated to be 1.26 nm. A mixture of blue-emitting Ca(2)PO(4)Cl:Eu(2+), green-emitting (Ba,Sr)(2)SiO(4):Eu(2+) and red-emitting CaAlSiN(3):Eu(2+) phosphors were selected in conjunction with 400 nm chip to fabricate white LED devices. The average color-rendering index R(a) and correlated color temperature (T(c)) of the white LEDs were found to be 93.4 and 4590 K, respectively. The results indicated that it was a promising candidate as a blue-emitting phosphor for the near-UV white light-emitting diodes.
Intense blue-emitting Ca2PO4Cl:Eu2+ phosphor for near-ultraviolet converting white light-emitting diodes
(2010-12-01)
Chiu, Yi-Chen
;
Liu, Wei-Ren
;
Chang, Chun-Kuei
;
Liao, Cheng-Chun
;
Yeh, Yao-Tsung
A blue phosphor Ca2PO4Cl:Eu2+ (CAP:Eu2+) was synthesized by solid state reaction. The Ca2PO4Cl:Eu2+ exhibited high quantum efficiency and excellent thermal stability. The luminescent intensity of Ca2PO4Cl:Eu2+ was found to be 128% under excitation at 380 nm, 149% under 400 nm, and 247% under 420 nm as high as that of BaMgAl10O17:Eu2+. The optimal doping concentration was observed to 11 mol.% of CAP:Eu2+. The energy transfer between Eu2+ ions in CAP were occurred via electric multipolar interaction, and the critical transfer distance was estimated to be 1.26 nm. A mixture of blue-emitting Ca2PO4Cl:Eu2+, green-emitting (Ba,Sr)(2)SiO4:Eu2+ and red-emitting CaAlSiN3:Eu2+ phosphors were selected in conjunction with 400 nm chip to fabricate white LED devices. The average color-rendering index R-a and correlated color temperature (T-c) of the white LEDs were found to be 93.4 and 4590 K, respectively. The results indicated that it was a promising candidate as a blue-emitting phosphor for the near-UV white light-emitting diodes.
Sr3B2O6 : Ce3+,Eu2+: A potential single-phased white-emitting borate phosphor for ultraviolet light-emitting diodes
(2007-08-20)
Chang, Chun-Kuei
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
The Ce3+/Eu2+ coactivated Sr3B2O6 phosphors exhibit varied hues from blue through white and eventually to yellow-orange by resonance-type energy transfer from Ce3+ to Eu2+ and tuning the relative proportion of Ce3+/Eu2+ properly. The authors have demonstrated that electric dipole-dipole interaction dominates the energy transfer mechanism in Sr3B2O6:Ce3+,Eu2+ phosphor, and the critical distance of energy transfer has been estimated to be about 30 A by both spectral overlap and concentration quenching methods. They have also shown that under the excitation of UV radiation, white light is generated by coupling 434 and 574 nm emission bands attributed to Ce3+ and Eu2+ radiations, respectively.
White light generation under violet-blue excitation from tunable green-to-red emitting Ca2MgSi2O7 : Eu,Mn through energy transfer
(2007-04-16)
Chang, Chun-Kuei
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
Yellowish green-to-orange red emission can be generated by energy transfer from Eu2+ to Mn2+ in the Ca2MgSi2O7 host matrix. Eu2+-doped Ca2MgSi2O7 shows a broad green emission band centering at 528 nm and Mn2+-doped Ca2MgSi2O7 exhibits a red emission at around 602 nm. The authors have demonstrated that the mechanism of energy transfer from Eu2+ to Mn2+ in Ca2MgSi2O7:Eu,Mn phosphor is a resonant type via a dipole-quadrupole mechanism. They have also shown that the white light with varied hue, depending on contents of Mn2+, is generated by combination of predesigned emission wavelength-tunable Ca2MgSi2O7:Eu,Mn phosphors and violet-blue light source. (c) 2007 American Institute of Physics.
WHITE-EMITTING PHOSPHORS AND LIGHTING APPARATUS USING THE SAME
(2010-01-28)
Chen, Teng-Ming
;
Chang, Chun-Kuei
A phosphor has a general formula of (M1-m-nCemEun)3Al2O5X2, wherein M is at least one selected from the group consisting of Ca, Sr and Ba; and X is at least one selected from the group consisting of Cl and Br, while 0