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Synthesis and luminescent properties of polymer-silica multilayer-encapsulated perovskite quantum dots for optoelectronics
(1970-01-01)
Liu, Shuang-De
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
Hydrophobic all-inorganic perovskite quantum dots (IPQDs) CsPbX3 (X = Cl, Br, and I) were synthesized using conventional solution methods. IPQDs are potential materials for lasers, solar cells, and displays because of their narrow full width at half-maximum, optically tunable wavelength, and great photoluminescence quantum yield. Their shortcomings are structurally unstable and moisture sensitive. To overcome the poor stability, we have developed a chemical modification to form GQD + PMAO@SiO2 that enhances their photoluminescence quantum yield (from 60 to similar to 90%), thermal stability (from 60 to similar to 90 degrees C), and photochemical stability. The combination of the green-emitting GQD + PMAO@SiO2 and red-emitting RQD + PMAO with a 450 nm blue InGaN-based LED chip was used to fabricate a white light emitting diode with the correlated color temperature (CCT) value of 6,943 K and Commission Internationale del'Eclairage of (0.312, 0.290).
Luminescent Properties and Energy Transfer of Green-Emitting Ca3Y2(Si3O9)(2):Ce3+,Tb3+ Phosphor
(2009-01-01)
Chiu, Yi-Chen
;
Liu, Wei-Ren
;
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.
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.
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.
Optical Study of Multiple-layered Colloidal Quantum Dots
(2015)
Chen, Yin-Han
;
Hsu, Shun-Chieh
;
Lin, Shih-Li
;
Chen, Teng-Ming
;
Lin, Chien-Chung
The photoluminescence (PL) with CdTe quantum dots (QDs) -NaCl crystals, mixed with organic film on glass substrate, was measured. This organic film was made by Polydimethylsiloxane (PDMS). Under different overlapping manner, a better PL intensity can be found at multiple layers condition.
Novel Reddish-Orange-Emitting BaLa2Si2S8:Eu2+ Thiosilicate Phosphor for LED Lighting
(2015-01-14)
Lee, Szu-Ping
;
Chan, Ting-Shan
;
Chen, Teng-Ming
;
應用化學系
;
應用化學系分子科學碩博班
A novel reddish-orange-emitting BaLa2Si2S8:Eu2+ thiosilicate was prepared in a sealed fused silica ampule and its crystal structure was refined using Rietveld methods. The BaLa2Si2S8:Eu2+ phosphor is excitable over a broad range from UV to blue (350-450 nm) and generated a reddish-orange broadband emission peaking at 645 nm with a quantum efficiency of similar to 24%. The thermal luminescence quenching of BaLa2Si2S8:Eu2+ was investigated over the range 25 to 150 degrees C. This phosphor was utilized to incorporate with two commercially available phosphors, blue BaMgAl10O17:Eu2+ and green (Ba,Sr)(2)SiO4:Eu2+, and a near-UV LED chip (405 nm), a white light with Ra of similar to 94 was obtained.
Charge Transfer Luminescence of Several Zirconium-Containing Compounds Using Synchrotron Radiation
(2011)
Wang, De-Yin
;
Chen, Teng-Ming
;
Cheng, Bing-Ming
;
應用化學系
;
Department of Applied Chemistry
Photoluminescence properties of pristine and Eu(2+)-doped zirconates, viz. BaZr(PO(4))(2), BaZr(4)(PO(4))(6), Ba(2)Zr(2)Si(3)O(12), and Ca(3)ZrSi(2)O(9), excited by vacuum ultraviolet (VUV) light using synchrotron radiation were studied. The undoped zirconates show self-activated emission in the 300-340 nm region under VUV excitation, which is ascribed to the Zr(4+)-O(2-) charge transfer luminescence. Upon doping Eu(2+) into these compounds, no Eu(2+) emission was observed in the rest of compounds, except for a weak Eu(2+) emission observed in Ba(2)Zr(2)Si(3)O(12):Eu(2+). The quenching of Eu(2+) luminescence is rationalized as the presence of Zr(4+)-Eu(2+) metal-metal charge transfer. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3605475] All rights reserved.
New Ce3+-Activated Thiosilicate Phosphor for LED Lighting-Synthesis, Luminescence Studies, and Applications
(2014-05-28)
Lee, Szu-Ping
;
Huang, Chien-Hao
;
Chan, Ting-Shan
;
Chen, Teng-Ming
;
應用化學系
A new Ce3+-activated thiosilicate phosphor, BaLa2Si2S8:Ce3+, was synthesized by using solid-state methods in a fused silica ampule and found to crystallize in the structure type of La2PbSi2S8. The crystal structure has been characterized by synchrotron X-ray diffraction and refined with Rietveld methods. This novel cyan-emitting phosphor can be excited over a broad range from UV to blue light (380-450 nm) and generates a broadband emission peaking at 471 nm with a quantum efficiency of 36%. Nonradiative transitions between Ce3+ ions in BaLa2Si2S8:Ce3+ have also been demonstrated to be attributable to dipole-dipole interactions, and the critical distance was calculated to be 17.41 angstrom. When BaLa2Si2S8:Ce3+ phosphor was utilized to incorporate with yellow-emitting (Sr,Ca)(2)SiO4:Eu2+ phosphor and red-emitting CaAlSiN3:Eu2+ phosphor on a 430 nm blue LED chip, a warm white light LED device with color rendering index of similar to 96 was obtained. The results indicate that cyan-emitting BaLa2Si2S8:Ce3+ can serve as a potential phosphor for incorporation in fabrication of solid-state lighting. The preparation, spectroscopic characterization, quantum efficiency, decay lifetime, thermal-quenching behavior, and related LED device data are also presented.
Eu2+-Activated Sr8ZnSc(PO4)(7): A Novel Near-Ultraviolet Converting Yellow-Emitting Phosphor for White Light-Emitting Diodes
(2012-12-01)
Huang, Chien-Hao
;
Chiu, Yi-Chen
;
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.
Effect of substituents on the photoluminescent and electroluminescent properties of substituted cyclometalated iridium(III) complexes
(2007-01-15)
Hong, Hsiao-Wen
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
The photophysics of octahedral 4d(6) and 5d(6) Complexes has been studied extensively. The d(6) iridium(III) complexes show intense phosphorescence at room temperature. Our goal of this research is to study the synthesis, characterization and applications of the light emitting dopants based on iridium(III) complexes. We have prepared and characterized a series of substituted (4-CF3, 4-Me, 4-OMe, 4-F, 3-F) 2-phenylbenzoxazole ligand. The intermediate di-irrido and the six-coordinated mononuclear iridium(III) dopants of the above ligands have been synthesized and characterized. These complexes are thermally stable between 280-320 degrees C depending upon the substituents and sublimable. They emit bright yellow to green light. The peak emission wavelengths of the dopants can be finely tuned depending upon the electronic properties of the substituents as well as their positions in the ring. The emission spectral diagrams show that the emissive states of the complexes have major contribution of MLCT state. In the absorption spectra, the (MLCT)-M-1 and (MLCT)-M-3 transitions have been resolved in the range, 385-500 nm. The physical parameters of the electroluminescent devices for the substituted and the unsubstituted complexes has been compared and discussed. (c) 2006 Elsevier B.V. All rights reserved.

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