Browsing by Author "Jang, Shyue-Ming"

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A Single-Phased Emission-Tunable Phosphor Ca(9)Y(PO(4))(7):Eu(2+),Mn(2+) with Efficient Energy Transfer for White-Light-Emitting Diodes
(2010-01-01)
Huang, Chien-Hao
;
Chen, Teng-Ming
;
Liu, Wei-Ren
;
Chiu, Yi-Chen
;
Yeh, Yao-Tsung
A series of single-composition emission-tunable Ca(9)Y(PO(4))(7):Eu(2+),Mn(2+) phosphors were synthesized by solid-state reaction. The energy transfer from Eu(2+) to Mn(2+) in Ca(9)Y(PO(4))(7) host matrix was studied and demonstrated to be a resonant type via a dipole-quadrupole mechanism with the critical distance of similar to 11 angstrom. The wavelength-tunable white light can be realized by coupling the emission bands centered at 486 and 638 nm ascribed to the contribution From Eu(2+) and Mn(2+), respectively. By properly tuning the relative composition of Eu(2+)/Mn(2+), chromaticity coordinates of (0.31, 0.33) can be achieved under excitation at 250-440 nm. Moreover, white-light-emitting diodes were fabricated through the integration of 365 nm chips and single composition white-light-emitting phosphors (Ca(0.975)Eu(0.01)Mn(0.015))(9)Y(PO(4))(7) into a single package shows a cool white light of 7200 K, color rendering index of 76, and color coordinates of (0.30, 0.31) close to that of ideal white light can be achieved.
A Single-Phased Emission-Tunable Phosphor Ca9Y(PO4)(7):Eu2+,Mn2+ with Efficient Energy Transfer for White-Light-Emitting Diodes
(2010-01-01)
Huang, Chien-Hao
;
Chen, Teng-Ming
;
Liu, Wei-Ren
;
Chiu, Yi-Chen
;
Yeh, Yao-Tsung
A series of single-composition emission-tunable Ca9Y(PO4)(7):Eu2+,Mn2+ phosphors were synthesized by solid-state reaction. The energy transfer from Eu2+ to Mn2+ in Ca9Y(PO4)(7) host matrix was studied and demonstrated to be a resonant type via a dipole-quadrupole mechanism with the critical distance of similar to 11 angstrom. The wavelength-tunable white light can be realized by coupling the emission bands centered at 486 and 638 nm ascribed to the contribution From Eu2+ and Mn2+, respectively. By properly tuning the relative composition of Eu2+/Mn2+, chromaticity coordinates of (0.31, 0.33) can be achieved under excitation at 250-440 nm. Moreover, white-light-emitting diodes were fabricated through the integration of 365 nm chips and single composition white-light-emitting phosphors (Ca0.975Eu0.01Mn0.015)(9)Y(PO4)(7) into a single package shows a cool white light of 7200 K, color rendering index of 76, and color coordinates of (0.30, 0.31) close to that of ideal white light can be achieved.
A study on the luminescence properties of CaAlBO(4): RE(3+) (RE=Ce, Tb, and Eu) phosphors
(2008)
Liu, Wei-Ren
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Chiu, Yi-Chen
;
Tung, Chien-Yueh
;
Yeh, Yao-Tsung
;
Jang, Shyue-Ming
A series of new phosphors of CaAlBO(4):RE(3+) (RE=Ce, Tb, Eu) were synthesized by conventional solid-state reactions. The X-ray diffraction data indicate that a pure phase of CaAlBO(4):RE(3+) can be successfully obtained. The photoluminescence (PL) spectra, quantum efficiency, and CIE coordinates of CaAlBO(4):RE(3+) were investigated. The PL and PL excitation spectra indicate that the emission wavelengths of CaAlBO(4):Ce(3+) are 372 and 398 nm (with full width at half maximum of 33 nm) attributed to the 4f(6)5d-4f(7) transition of the Ce(3+) activator, respectively. CaAlBO(4):Tb(3+) displays green emission at 483, 543, 584, and 620 nm, while CaAlBO(4):Eu(3+) shows a dominating emission peak at 621 nm, which is attributed to the Eu(3+) (5)D(0)-(7)F(2) transition. The quantum efficiencies of optimized CaAlBO(4):Ce(3+), CaAlBO(4):Tb(3+), and CaAlBO(4):Eu(3+) were found to be 43, 21, and 19%, respectively. The phosphors may provide a new kind of luminescent material under UV excitation. (C) 2008 The Electrochemical Society.
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.
Eu(2+)-activated silicon-oxynitride Ca(3)Si(2)O(4)N(2): a green-emitting phosphor for white LEDs
(2011-05-09)
Chiu, Yi-Chen
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Huang, Chien-Hao
;
Lee, Te-Ju
;
Liu, Wei-Ren
;
Yeh, Yao-Tsung
The green-emitting phosphor Ca(3)Si(2)O(4)N(2):Eu(2+) was synthesized using a solid-state reaction. The luminescence properties, diffuse reflection spectrum, and thermal quenching were firstly studied, and a white light-emitting diode (wLED) was fabricated using the Eu(2+)-activated Ca(3)Si(2)O(4)N(2) phosphor. Eu(2+)-doped Ca(3)Si(2)O(4)N(2) exhibited a broad green emission band centered between 510 and 550 nm depending on the concentration of Eu(2+). The optimal doping concentration of Eu(2+) in Ca(3)Si(2)O(4)N(2) was 1 mol%. The energy transfer between Eu(2+) ions proceeds by an electric multipolar interaction mechanism, with a critical transfer distance of approximately 30.08 angstrom. A wLED with an color-rendering index R(a) of 88.25 at a correlated color temperature of 6029 K was obtained by combining a GaN-based n-UV LED (380 nm) with the blue-emitting BaMgAl(10)O(17):Eu(2+), green-emitting Ca(3)Si(2)O(4)N(2): Eu(2+), and red-emitting CaAlSiN(3):Eu(2+) phosphors. The results present Ca(3)Si(2)O(4)N(2):Eu(2+) as an attractive candidate for use as a conversion phosphor for wLED applications. (C) 2011 Optical Society of America
Eu2+-activated silicon-oxynitride Ca3Si2O4N2: a green-emitting phosphor for white LEDs
(2011-05-09)
Chiu, Yi-Chen
;
Huang, Chien-Hao
;
Lee, Te-Ju
;
Liu, Wei-Ren
;
Yeh, Yao-Tsung
The green-emitting phosphor Ca3Si2O4N2:Eu2+ was synthesized using a solid-state reaction. The luminescence properties, diffuse reflection spectrum, and thermal quenching were firstly studied, and a white light-emitting diode (wLED) was fabricated using the Eu2+-activated Ca3Si2O4N2 phosphor. Eu2+-doped Ca3Si2O4N2 exhibited a broad green emission band centered between 510 and 550 nm depending on the concentration of Eu2+. The optimal doping concentration of Eu2+ in Ca3Si2O4N2 was 1 mol%. The energy transfer between Eu2+ ions proceeds by an electric multipolar interaction mechanism, with a critical transfer distance of approximately 30.08 angstrom. A wLED with an color-rendering index R-a of 88.25 at a correlated color temperature of 6029 K was obtained by combining a GaN-based n-UV LED (380 nm) with the blue-emitting BaMgAl10O17:Eu2+, green-emitting Ca3Si2O4N2: Eu2+, and red-emitting CaAlSiN3:Eu2+ phosphors. The results present Ca3Si2O4N2:Eu2+ as an attractive candidate for use as a conversion phosphor for wLED applications. (C) 2011 Optical Society of America
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.
Luminescence and Energy Transfer Mechanism in Ca(10)K(PO(4))(7):Eu(2+), Mn(2+) Phosphor
(2009-01-01)
Liu, Wei-Ren
;
Chiu, Yi-Chen
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Yeh, Yao-Tsung
;
Jang, Shyue-Ming
;
Chen, Teng-Ming
A series of Ca(10)K(PO(4))(7):Eu(2+), Mn(2+) (CKP: Eu(2+), Mn(2+)) phosphors was synthesized by solid-state reaction. Under an optimal excitation of 347 nm, we have observed a blue emission band at 467 nm and a red emission band at 634 nm, which resulted from Eu(2+) and Mn(2+), respectively. The energy transfer from Eu(2+) to Mn(2+) in CKP host matrix is of a resonant type via a dipole quadrupole mechanism. By properly varying the ratio of Eu/Mn, the emission hue can be tuned from blue (0.18,0.21), to white (0.30,0.24), and finally to red (0.35,0.24). The intensity of composition-optimized CKP:Eu(2+) is about 30% of BaMgAl(10)O(17): Eu(2+). The measurement of thermal quenching for CKP: Eu(2+), Mn(2+) and yttrium aluminum garnet:Ce(3+) was also compared and investigated in the study. The (CKP: Eu(2+),Mn(2+)) phosphor may serve as a candidate for UV light-emitting diode application. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3121531] All rights reserved.
Luminescence and Energy Transfer Mechanism in Ca10K(PO4)(7):Eu2+, Mn2+ Phosphor
(2009-01-01)
Liu, Wei-Ren
;
Chiu, Yi-Chen
;
Yeh, Yao-Tsung
;
Jang, Shyue-Ming
;
Chen, Teng-Ming
A series of Ca10K(PO4)(7):Eu2+, Mn2+ (CKP: Eu2+, Mn2+) phosphors was synthesized by solid-state reaction. Under an optimal excitation of 347 nm, we have observed a blue emission band at 467 nm and a red emission band at 634 nm, which resulted from Eu2+ and Mn2+, respectively. The energy transfer from Eu2+ to Mn2+ in CKP host matrix is of a resonant type via a dipole quadrupole mechanism. By properly varying the ratio of Eu/Mn, the emission hue can be tuned from blue (0.18,0.21), to white (0.30,0.24), and finally to red (0.35,0.24). The intensity of composition-optimized CKP:Eu2+ is about 30% of BaMgAl10O17: Eu2+. The measurement of thermal quenching for CKP: Eu2+, Mn2+ and yttrium aluminum garnet:Ce3+ was also compared and investigated in the study. The (CKP: Eu2+,Mn2+) phosphor may serve as a candidate for UV light-emitting diode application. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3121531] All rights reserved.
Luminescent Properties and Energy Transfer of Green-Emitting Ca(3)Y(2)(Si(3)O(9))(2):Ce(3+),Tb(3+) Phosphor
(2009-01-01)
Chiu, Yi-Chen
;
Liu, Wei-Ren
;
Yeh, Yao-Tsung
;
Jang, Shyue-Ming
;
Chen, Teng-Ming
Green-emitting phosphors of Ca(3)Y(2)(Si(3)O(9))(2):Ce(3+),Tb(3+) have been synthesized by solid-state reaction. The luminescence properties were characterized by photoluminescence (PL) and photoluminescence excitation spectra, reflection spectra, and a detection system using an integrating sphere equipped with a spectrofluorometer. With Ce(3+) co-doping as a sensitizer, the PL intensity of Ca(3)Y(2)(Si(3)O(9))(2):Ce(3+),Tb(3+) was found to increase dramatically by a factor of 5.8. For comparison, the emission intensity of composition-optimized Ca(3)Y(2)(Si(3)O(9))(2):Ce(3+),Tb(3+) is 126% of green commodity, ZnS:Cu,Al. The quantum efficiency of Ca(3)Y(2)(Si(3)O(9))(2):Ce(3+),Tb(3+) is as high as 77% compared to ZnS:Cu,Al (53%). The energy transfer from Ce(3+) to Tb(3+) is also of resonant type via a dipole-dipole mechanism with the energy-transfer critical distance of 6.78 A degrees. By utilizing the principle of energy transfer and appropriate tuning of activator contents, we are currently evaluating the potential application of Ca(3)Y(2)(Si(3)O(9))(2):Ce(3+),Tb(3+) as a highly efficient UV-convertible phosphor.
Luminescent Properties and Energy Transfer of Green-Emitting Ca3Y2(Si3O9)(2):Ce3+,Tb3+ Phosphor
(2009-01-01)
Chiu, Yi-Chen
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Liu, Wei-Ren
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Yeh, Yao-Tsung
;
Jang, Shyue-Ming
;
Chen, Teng-Ming
Green-emitting phosphors of Ca3Y2(Si3O9)(2):Ce3+,Tb3+ have been synthesized by solid-state reaction. The luminescence properties were characterized by photoluminescence (PL) and photoluminescence excitation spectra, reflection spectra, and a detection system using an integrating sphere equipped with a spectrofluorometer. With Ce3+ co-doping as a sensitizer, the PL intensity of Ca3Y2(Si3O9)(2):Ce3+,Tb3+ was found to increase dramatically by a factor of 5.8. For comparison, the emission intensity of composition-optimized Ca3Y2(Si3O9)(2):Ce3+,Tb3+ is 126% of green commodity, ZnS:Cu,Al. The quantum efficiency of Ca3Y2(Si3O9)(2):Ce3+,Tb3+ is as high as 77% compared to ZnS:Cu,Al (53%). The energy transfer from Ce3+ to Tb3+ is also of resonant type via a dipole-dipole mechanism with the energy-transfer critical distance of 6.78 A degrees. By utilizing the principle of energy transfer and appropriate tuning of activator contents, we are currently evaluating the potential application of Ca3Y2(Si3O9)(2):Ce3+,Tb3+ as a highly efficient UV-convertible phosphor.
Synthesis and characterization of a new quaternary selenide Sr(3)GeSb(2)Se(8)
(2008-09-01)
Yu, Ching-Yi
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Wang, Ming-Fang
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Chung, Ming-Yang
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Jang, Shyue-Ming
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Huang, Jih-Chen
A new quaternary selenide Sr(3)GeSb(2)Se(8) has been synthesized at 750 degrees C from pure elements in a stoichiometric ratio under vacuum. The product as-synthesized is characterized by single-crystal X-ray diffraction, diffuse reflectance spectroscopy, and thermoanalysis. The title compound crystallizes in the orthorhombic space group Pnma with a = 12.633(4) angstrom, b = 4.301(1) angstrom, c = 28.693(7) angstrom, V = 1558.8(8) angstrom(3), Z = 4, R(1)/wR(2) = 0.0582/0.1221, and GOF = 1.077. The structure of Sr(3)GeSb(2)Se(8) features a new structural type that consists of one-dimensional chains of vertex-sharing tetrahedra (1)(infinity)[MSe(3)] (M = Ge/Sb) and fused double chains of edge-shared square pyramids (1)(infinity)[M(2)Se(5)], which are held together by Sr(2+) ions. A band gap of 0.75 eV for Sr(3)GeSb(2)Se(8) was derived from its diffuse reflectance spectrum. (C) 2007 Elsevier Masson SAS. All rights reserved.
Synthesis and characterization of quaternary chalcogenides InSn(2)Bi(3)Se(8) and In(0.2)Sn(6)Bi(1.8)Se(9)
(2009-06-01)
Wang, Ming-Fang
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Jang, Shyue-Ming
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Huang, Jih-Chen
;
Lee, Chi-Shen
;
應用化學系
Quaternary chalcogenides InSn(2)Bi(3)Se(8) and In(0.2)Sn(6)Bi(1.8)Se(9) were synthesized on direct combination of their elements in stoichiometric ratios at T>800 degrees C under vacuum. Their structures were determined with X-ray diffraction of single crystals. InSn(2)Bi(3)Se(8) crystallizes in monoclinic space group C2/m (No. 12) with a = 13.557(3) angstrom, b = 4.1299(8) angstrom, c = 15.252(3)angstrom, beta = 115.73(3)degrees, V = 769.3(3) angstrom(3), Z = 2, and R(1)/wR(2)/GOF = 0.0206/0.0497/1.092; In(0.2)Sn(6)Bi(1.8)Se(9) crystallizes in orthorhombic space group Cmc2(1) (No. 36) with a = 4.1810(8) angstrom, b = 13.799(3) angstrom, c = 31.953(6) angstrom, V=1843.4(6) angstrom(3), Z = 4, and R(1)/wR(2)/GOF = 0.0966/0.2327/1.12. InSn(2)Bi(3)Se(8) and In(0.2)Sn(6)Bi(1.8)Se(9) are isostructural with CuBi(5)S(8) and Bi(2)Pb(6)S(9) phases, respectively. The structures of InSn(2)Bi(3)Se(8) and In(0.2)Sn(6)Bi(1.8)Se(9) feature a three-dimensional framework containing slabs of NaCl-(311) type with varied thicknesses. Calculations of the electronic structure and measurements of electrical conductivity indicate that these materials are semiconductors with narrow band gaps. Both compounds show n-type semiconducting properties with Seebeck coefficients -270 and -230 mu V/K at 300 K for InSn(2)Bi(3)Se(8) and In(0.2)Sn(6)Bi(1.8)Se(9), respectively. (C) 2009 Elsevier Inc. All rights reserved.
Synthesis and characterization of quaternary chalcogenides InSn2Bi3Se8 and In0.2Sn6Bi1.8Se9
(2009-06-01)
Wang, Ming-Fang
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Jang, Shyue-Ming
;
Huang, Jih-Chen
;
Lee, Chi-Shen
;
應用化學系
Quaternary chalcogenides InSn2Bi3Se8 and In0.2Sn6Bi1.8Se9 were synthesized on direct combination of their elements in stoichiometric ratios at T>800 degrees C under vacuum. Their structures were determined with X-ray diffraction of single crystals. InSn2Bi3Se8 crystallizes in monoclinic space group C2/m (No. 12) with a = 13.557(3) angstrom, b = 4.1299(8) angstrom, c = 15.252(3)angstrom, beta = 115.73(3)degrees, V = 769.3(3) angstrom(3), Z = 2, and R-1/wR(2)/GOF = 0.0206/0.0497/1.092; In0.2Sn6Bi1.8Se9 crystallizes in orthorhombic space group Cmc2(1) (No. 36) with a = 4.1810(8) angstrom, b = 13.799(3) angstrom, c = 31.953(6) angstrom, V=1843.4(6) angstrom(3), Z = 4, and R-1/wR(2)/GOF = 0.0966/0.2327/1.12. InSn2Bi3Se8 and In0.2Sn6Bi1.8Se9 are isostructural with CuBi5S8 and Bi2Pb6S9 phases, respectively. The structures of InSn2Bi3Se8 and In0.2Sn6Bi1.8Se9 feature a three-dimensional framework containing slabs of NaCl-(311) type with varied thicknesses. Calculations of the electronic structure and measurements of electrical conductivity indicate that these materials are semiconductors with narrow band gaps. Both compounds show n-type semiconducting properties with Seebeck coefficients -270 and -230 mu V/K at 300 K for InSn2Bi3Se8 and In0.2Sn6Bi1.8Se9, respectively. (C) 2009 Elsevier Inc. All rights reserved.