Browsing by Author "Chiu, Yi-Chen"

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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
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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.
Anomalous luminescence from Yb2+-doped Ca2PO4Cl
(2014-04-01)
Wang, De-Yin
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Chiu, Yi-Chen
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Huang, Chien-Hao
;
Wu, Yun-Chen
;
Chen, Teng-Ming
The photoluminescence of Ca2PO4Cl:Yb2+ has been investigated and compared with that of Ca2PO4Cl: Eu2+, and the application of Ca2PO4Cl:Yb2+ for white LED has been evaluated. The excitation spectra of Ca2PO4Cl:Yb2+ are dominated by an intense excitation band at 395 nm. Under near DV excitation at 395 nm, Ca2PO4Cl:Yb2+ shows a broad asymmetric emission with maximum at 490 nm. This emissions result from two different Yb2+ centers is evidenced by the low temperature (T=100 K) emission spectrum. Yb2+ luminescence differs significantly from that of Eu2+, most notably in the structure of emission spectra, and is characterized by a much broader emission band and lower quenching temperature. Such anomalous luminescence from Yb2+ is ascribed to the de-excitation process of the Yb2+-trapped exciton state. Ca2PO4Cl:Yb2+ has external quantum efficiency of 24% and exhibits 40% of luminescence quenching at 100 degrees C in the air and, therefore, these results reveal its limited potential in the fabrication of white-light LEDs. (C) 2013 Elsevier B.V. All rights reserved.
(Ba,Sr)Y(2)Si(2)Al(2)O(2)N(5):Eu(2+): a novel near-ultraviolet converting green phosphor for white light-emitting diodes
(2011-01-01)
Liu, Wei-Ren
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Yeh, Chiao-Wen
;
Huang, Chien-Hao
;
Lin, Chun Che
;
Chiu, Yi-Chen
A highly intense green-emitting phosphor BaY(2)Si(2)Al(2)O(2)N(5) : Eu(2+) (BYN : Eu(2+)) peaking at 511 nm was synthesized by a solid state reaction. The structure refinement, luminescence properties of BYN : Eu(2+) phosphors as well as their thermal quenching and the fabrication of white-light-emitting diodes (W-LEDs) were firstly investigated. By partially substituting Ba by Sr, namely (Ba, Sr)Y(2)Si(2)Al(2)O(2)N(5) : Eu(2+) (BSYN : Eu(2+)), the emission peak was shifted to 565 nm, giving a yellow-orange color, due to the splitting of the 5d energy level. By utilizing a mixture of blue-emitting BaMgAl(10)O(17) : Eu(2+), green-emitting BYN : Eu(2+) and red-emitting CaAlSiN(3) : Eu(2+) phosphors as light converters, an intense white GaN-based n-UV-LED (380 nm) was fabricated to a exhibit good color-rendering index R(a) of 84.5 at a correlated color temperature of 5089 K and CIE coordinates of (0.3425, 0.3478). Based on these results, we are currently evaluating the potential application of BYN : Eu(2+) as a green-emitting near-UV convertible phosphor.
(Ba,Sr)Y2Si2Al2O2N5:Eu2+: a novel near-ultraviolet converting green phosphor for white light-emitting diodes
(2011-01-01)
Liu, Wei-Ren
;
Yeh, Chiao-Wen
;
Huang, Chien-Hao
;
Lin, Chun Che
;
Chiu, Yi-Chen
A highly intense green-emitting phosphor BaY2Si2Al2O2N5 : Eu2+ (BYN : Eu2+) peaking at 511 nm was synthesized by a solid state reaction. The structure refinement, luminescence properties of BYN : Eu2+ phosphors as well as their thermal quenching and the fabrication of white-light-emitting diodes (W-LEDs) were firstly investigated. By partially substituting Ba by Sr, namely (Ba, Sr)Y2Si2Al2O2N5 : Eu2+ (BSYN : Eu2+), the emission peak was shifted to 565 nm, giving a yellow-orange color, due to the splitting of the 5d energy level. By utilizing a mixture of blue-emitting BaMgAl10O17 : Eu2+, green-emitting BYN : Eu2+ and red-emitting CaAlSiN3 : Eu2+ phosphors as light converters, an intense white GaN-based n-UV-LED (380 nm) was fabricated to a exhibit good color-rendering index R-a of 84.5 at a correlated color temperature of 5089 K and CIE coordinates of (0.3425, 0.3478). Based on these results, we are currently evaluating the potential application of BYN : Eu2+ as a green-emitting near-UV convertible phosphor.
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.
Crystal structure of blue-white-yellow color-tunable Ca4Si2O7F2:Eu2+,Mn2+ phosphor and investigation of color tunability through energy transfer for single-phase white-light near-ultraviolet LEDs
(2012)
Huang, Chien-Hao
;
Chan, Ting-Shan
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Liu, Wei-Ren
;
Wang, De-Yin
;
Chiu, Yi-Chen
The crystal structure of Ca4Si2O7F2:Eu2+,Mn2+ was refined and determined from X-ray diffraction (XRD) profiles obtained using a synchrotron light source by the Rietveld refinement method. It was found to crystallize into a monoclinic structure with the P2(1)/c(14) space group. On examining the Mn2+-concentration-dependent photoluminescence properties, we found that the emission colors could be tuned from blue (0.152, 0.112) to white-light (0.351, 0.332) and eventually to yellow (0.430, 0.423) through energy transfer by changing the Eu2+/Mn2+ ratio. Moreover, energy transfer from a sensitizer Eu2+ to an activator Mn2+ occurs via a resonance-type dipole-quadrupole interaction mechanism, and the critical distances of the energy transfer were calculated to be 11.66 angstrom and 12.61 angstrom using concentration quenching and spectral overlap methods, respectively. Combining a 400 nm near-ultraviolet (NUV) chip and a single-phase white-emitting (Ca0.96Eu0.01Mn0.03)(4)Si2O7F2 phosphor produced a white-light NUV LED with CIE chromaticity coordinates of (0.347, 0.338) and a warm color temperature of 4880 K.
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
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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
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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
Eu2+-Activated Sr8ZnSc(PO4)(7): A Novel Near-Ultraviolet Converting Yellow-Emitting Phosphor for White Light-Emitting Diodes
(2012-12-01)
Huang, Chien-Hao
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Chiu, Yi-Chen
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Yeh, Yao-Tsung
;
Chan, Ting-Shan
;
Chen, Teng-Ming
The crystal structure of Eu2+-activated Sr8ZnSc(PO4)(7):Eu2+ phosphor was refined and determined from XRD profiles by the Rietveld refinement method using a synchrotron light source. This phosphor crystallizes in the monoclinic structure with the I2/a space group. The SZSP:xEu(2+) phosphors showed a broad yellow emission band centered at 511 and 571 nm depending on the concentration of Eu2+, and the composition-optimized concentration of Eu2+ in the Sr8ZnSc(PO4)(7):Eu2+ phosphor was determined to be 2 mol %. The estimated crystal-field splitting and CIE chromaticity coordinates of Sr8ZnSc(PO4)(7):xEu(2+) (x = 0.001-0.05 mol) were 20181-20983 cm(-1) and (0.3835, 0.5074) to (0.4221, 0.5012), respectively, and the emission band showed a redshift from 547 to 571 nm with increasing Eu2+ concentration. The nonradiative transitions between the Eu2+ ions in the Sr8ZnSc(PO4)(7) host were attributable to dipole-dipole interactions, and the critical distance was approximately 19.8 angstrom. The combination of a 400 nm NUV chip with a blend of Sr8ZnSc(PO4)(7):0.02Eu(2+) and BAM:Eu2+ phosphors (light converters) gave high color rendering indices between 79.38 and 92.88, correlated color temperatures between 4325 and 7937 K, and tuned CIE chromaticity coordinates in the range (0.381, 0.435) to (0.294, 0.310), respectively, depending on the SZSP:0.02Eu(2+)/BAM:Eu2+ weight ratio. These results suggest that the Sr8ZnSc(PO4)(7):0.02Eu(2+)/BAM:Eu2+ phosphor blend has potential applications in white NUV LEDs.
Green-emitting phosphors and process for producing the same
(2008-10-02)
Chen, Teng-Ming
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Chiu, Yi-Chen
This invention relates to a green phosphor and a process for producing the same, wherein the phosphor is represented by a chemical formula: M(Tb1-xLax)4Si3O13, where M includes at least one of Ca and Sr, and 0
High efficiency and high color purity blue-emitting NaSrBO(3):Ce(3+) phosphor for near-UV light-emitting diodes
(2011-01-01)
Liu, Wei-Ren
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Huang, Chien-Hao
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Wu, Chih-Pin
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Chiu, Yi-Chen
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Yeh, Yao-Tsung
A highly intense blue-emitting phosphor NaSrBO(3):Ce(3+), peaking at 400 nm was synthesized by a solid state reaction. The crystal structure, luminescence properties and quantum efficiency of NaSrBO(3):Ce(3+) phosphors, as well as their thermal quenching capabilities and the fabrication of a 370 nm UV-chip and R/G/B phosphors were investigated for the first time. The composition-optimized NaSrBO(3):1% Ce(3+) exhibited high external quantum efficiency of 89% of the blue-emitting, commercial compound, BaMgAl(10)O(17):Eu(2+) (BAM:Eu(2+)). The color purity of as-synthesized NaSrBO(3):1% Ce(3+) phosphor is much better than that of BAM:Eu(2+). By using a GaN-based UV-LED (370 nm) and a mixture of blue-emitting NaSrBO(3):Ce(3+), green-emitting (Ba,Sr)(2)SiO(4):Eu(2+) and red-emitting CaAlSiN(3):Eu(2+) phosphors as light converters, we constructed an intense white light emitting diode. The LED device exhibited an excellent color-rendering index R(a) of 93.13 at a correlated color temperature of 5763 K with CIE coordinates of (0.324,0.337) and a maximum lumen efficacy of 26.2 lmW(-1). Based on the results, we are currently evaluating the potential application of NaSrBO(3):Ce(3+) as a blue-emitting UV convertible phosphor.
High efficiency and high color purity blue-emitting NaSrBO3:Ce3+ phosphor for near-UV light-emitting diodes
(2011-01-01)
Liu, Wei-Ren
;
Huang, Chien-Hao
;
Wu, Chih-Pin
;
Chiu, Yi-Chen
;
Yeh, Yao-Tsung
A highly intense blue-emitting phosphor NaSrBO3:Ce3+, peaking at 400 nm was synthesized by a solid state reaction. The crystal structure, luminescence properties and quantum efficiency of NaSrBO3:Ce3+ phosphors, as well as their thermal quenching capabilities and the fabrication of a 370 nm UV-chip and R/G/B phosphors were investigated for the first time. The composition-optimized NaSrBO3:1% Ce3+ exhibited high external quantum efficiency of 89% of the blue-emitting, commercial compound, BaMgAl10O17:Eu2+ (BAM:Eu2+). The color purity of as-synthesized NaSrBO3:1% Ce3+ phosphor is much better than that of BAM:Eu2+. By using a GaN-based UV-LED (370 nm) and a mixture of blue-emitting NaSrBO3:Ce3+, green-emitting (Ba,Sr)(2)SiO4:Eu2+ and red-emitting CaAlSiN3:Eu2+ phosphors as light converters, we constructed an intense white light emitting diode. The LED device exhibited an excellent color-rendering index R-a of 93.13 at a correlated color temperature of 5763 K with CIE coordinates of (0.324,0.337) and a maximum lumen efficacy of 26.2 lmW(-1). Based on the results, we are currently evaluating the potential application of NaSrBO3:Ce3+ as a blue-emitting 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.
Luminescence and Energy Transfer Mechanism in Ca(10)K(PO(4))(7):Eu(2+), Mn(2+) Phosphor
(2009-01-01)
Liu, Wei-Ren
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Chiu, Yi-Chen
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Yeh, Yao-Tsung
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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
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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.