Browsing by Author "Liu, Wei-Ren"

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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.
(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
;
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.
Correlation between photoluminescence and varied growth pressure of well-aligned ZnO nanorods on fused silica substrate
(2007-11-01)
Yang, Song
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Hsu, Hsu-Cheng
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Liu, Wei-Ren
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Cheng, Hsin-Min
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Hsieh, Wen-Feng
Well-aligned ZnO nanorods with variable diameters were fabricated on fused silica substrates by the simple physical vapor deposition method with and without pre-deposited NiO particles. The diameter control of ZnO nanorods on the fused silica substrates was achieved by varying the growth pressure. The room-temperature photoluminescence spectra of the ZnO nanorods exhibit strong exciton emission at 3.25 eV that reveals good crystal quality. The exciton emission peak shifts toward 3.22 eV for the samples made at the larger growth pressure that is attributed to the influence of the electron-acceptor-level transition. The ZnO nanorods were examined by high resolution transmission electron microscopy and X-ray diffraction to show single crystal quality and preferentially c-axis alignment. Furthermore, we used scanning electron microscope to verify not only the size but also the growth mechanisms of ZnO nanorods. The results show a ZnO buffer layer formed between the flat top-facet nanorods and the substrate. In comparison with the samples without pre-deposited NiO particles on the substrate, the pre-deposited NiO particles act as nucleation centers for Zn vapor during the deposition process that improves the quality of the buffer layer. (C) 2007 Elsevier B.V. All rights reserved.
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
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Chan, Ting-Shan
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Liu, Wei-Ren
;
Wang, De-Yin
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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.
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
Enhanced Conversion Efficiency of III-V Triple-junction Solar Cells with Graphene Quantum Dots
(2016-12-16)
Lin, Tzu-Neng
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Santiago, Svette Reina Merden S.
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Zheng, Jie-An
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Chao, Yu-Chiang
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Yuan, Chi-Tsu
Graphene has been used to synthesize graphene quantum dots (GQDs) via pulsed laser ablation. By depositing the synthesized GQDs on the surface of InGaP/InGaAs/Ge triple-junction solar cells, the short-circuit current, fill factor, and conversion efficiency were enhanced remarkably. As the GQD concentration is increased, the conversion efficiency in the solar cell increases accordingly. A conversion efficiency of 33.2% for InGaP/InGaAs/Ge triple-junction solar cells has been achieved at the GQD concentration of 1.2 mg/ml, corresponding to a 35% enhancement compared to the cell without GQDs. On the basis of time-resolved photoluminescence, external quantum efficiency, and work-function measurements, we suggest that the efficiency enhancement in the InGaP/InGaAs/Ge triple-junction solar cells is primarily caused by the carrier injection from GQDs to the
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
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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
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Lee, Te-Ju
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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
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
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Liu, Wei-Ren
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Chen, Teng-Ming
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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
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
;
Wu, Chih-Pin
;
Chiu, Yi-Chen
;
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.