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Now showing 1 - 10 of 59

Resonant-enhanced full-color emission of quantum-dot-based micro LED display technology
(2015-12-14)
Han, Hau-Vei
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Lin, Huang-Yu
;
Lin, Chien-Chung
;
Chong, Wing-Cheung
;
Li, Jie-Ru
Colloidal quantum dots which can emit red, green, and blue colors are incorporated with a micro-LED array to demonstrate a feasible choice for future display technology. The pitch of the micro-LED array is 40 mu m, which is sufficient for high-resolution screen applications. The method that was used to spray the quantum dots in such tight space is called Aerosol Jet technology which uses atomizer and gas flow control to obtain uniform and controlled narrow spots. The ultra-violet LEDs are used in the array to excite the red, green and blue quantum dots on the top surface. To increase the utilization of the UV photons, a layer of distributed Bragg reflector was laid down on the device to reflect most of the leaked UV photons back to the quantum dot layers. With this mechanism, the enhanced luminous flux is 194% (blue), 173% (green) and 183% (red) more than that of the samples without the reflector. The luminous efficacy of radiation (LER) was measured under various currents and a value of 165 lm/Watt was recorded. (C)2015 Optical Society of America
An efficient green-emitting Ba5Si2O6Cl6:Eu2+ phosphor for white-light LED application
(2017-01-01)
Dutta, Somrita
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Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
A series of novel green-emitting Ba5Si2O6Cl6:Eu2+ (BSOC:Eu2+) phosphors were synthesized via the high-temperature solid-state reaction route. The phase identification, elemental distribution, reflectance spectra, luminescence, and thermal stability of the BSOC:Eu2+ phosphor and its applicability in white light-emitting diodes (WLEDs) were investigated in detail. The broad excitation spectrum was observed from UV to blue light which generated a broadband emission peaking at 510 nm for the present phosphor with a good quantum efficiency of 44% and thereby it is promising for solid-state lighting applications. Temperature-dependent luminescence measurements of the BSOC:Eu2+ phosphor from 25 degrees C to 250 degrees C were performed to obtain the thermal stability of the present phosphor. Finally, a WLED was fabricated using the green-emitting BSOC:Eu2+ phosphor and commercially available red and blue phosphors pumped with a 400 nm blue chip. The CIE parameters such as color coordinate, color rendering index, color correlated temperature and luminous efficacy of radiation of the fabricated LED were measured. The suitable excitation spectra, efficient and broad emission band and excellent color parameters suggest that the synthesized phosphor could be a potential material for WLED application.
Thermally stable green Ba3Y(PO4)(3):Ce3+,Tb3+ and red Ca3Y(AlO)(3)(BO3)(4):Eu3+ phosphors for white-light fluorescent lamps
(2011-01-03)
Huang, Chien-Hao
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Kuo, Te-Wen
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
A class of thermal stable of green-emitting phosphors Ba3Y(PO4)(3):Ce3+,Tb3+ (BYP:Ce3+,Tb3+) and red-emitting phosphors Ca3Y(AlO)(3)(BO3)(4):Eu3+ (CYAB:Eu3+) for white-light fluorescent lamps were synthesized by high temperature solid-state reaction. We observed a decay of only 3% at 150 degrees C for BYP:0.25Ce(3+),0.25Tb(3+) (3% for LaPO4:Ce3+,Tb3+), and a decay of 4% for CYAB:0.5Eu(3+) (7% for Y2O3:Eu3+, 24% for Y2O2S:Eu3+). The emission intensity of composition-optimized Ba-3(Y0.5Ce0.25Tb0.25)(PO4)(3) is 70% of that of commercial LaPO4:Ce3+,Tb3+ phosphors, and the CIE chromaticity coordinates are found to be (0.323, 0.534). The emission intensity of Ca-3(Y0.5Eu0.5)(AlO)(3)(BO3)(4) is 70% and 83% of those of Y2O3:Eu3+ and Y2O2S:Eu3+ phosphors, respectively, and the CIE chromaticity coordinates are redder (0.652, 0.342) than those of Y2O3:Eu3+ (0.645, 0.347) and Y2O2S:Eu3+ (0.647, 0.343). A white-light fluorescent lamp is fabricated using composition-optimized Ba-3(Y0.5Ce0.25Tb0.25)(PO4)(3) and Ca-3(Y0.5Eu0.5)(AlO)(3)(BO3)(4) phosphors and matching blue-emitting phosphors. The results indicate that the quality of the brightness and color reproduction is suitable for application in shortwave UV fluorescent lamps. The white-light fluorescent lamp displays CIE chromaticity coordinates of x = 0.33, y = 0.35, a warm white light with a correlated color temperature of 5646 K, and a color-rendering index of Ra = 70. (C) 2010 Optical Society of America
Novel yellowish-orange Sr8Al12O24S2:Eu2+ phosphor for application in blue light-emitting diode based white LED
(2010-06-21)
Kuo, Te-Wen
;
Huang, Chien-Hao
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
A new yellowish-orange phosphor, Sr8Al12O24S2:Eu2+, was synthesized by the solid-state method and its photoluminescence properties were investigated by excitation and emission spectra. Its excitation band is extending from 400-500 nm, which is adaptable to the emission band of blue LED chips (450-470 nm). Upon the excitation of 450 nm light, the phosphor exhibits strong yellowish-orange emission centered at 605 nm with good thermal stability. A white light-emitting diode (W-LED) that consists of a blue LED chip (similar to 470 nm) and a (Sr0.92Eu0.08)(8)Al12O24S2 phosphor is demonstrated. The CIE 1931 chromaticity coordinates (x, y) are (0.34, 0.25), the correlated color temperature (CCT) is 4300 K, and the luminous efficacy of this W-LED is 14.2 1m/W at room temperature and with a forward-bias current of 400 mA. (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
Ca9La(PO4)(7):Eu2+,Mn2+: an emission-tunable phosphor through efficient energy transfer for white light-emitting diodes
(2010-03-01)
Huang, Chien-Hao
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
We have synthesized a series of single-composition emission-tunable Ca9La(PO4)(7):Eu2+,Mn2+ (CLP:Eu2+,Mn2+) phosphors by solid state reactions. Through an effective resonance-type energy transfer, the CLP:Eu2+,Mn2+ phosphors exhibit a systematically varied hues from green, yellow, and eventually to red and the relative intensity of green and red emissions can be tuned by adjusting the concentration of Mn2+, respectively. The energy transfer from Eu2+ to Mn2+ in CLP:Eu2+,Mn2+ has been studied and demonstrated to be a resonant type via a dipole-quadrupole mechanism based on the decay lifetime data and the energy transfer critical distance was estimated to be 11.36 angstrom by using the spectral overlap methods. A warm white light emitting diode (WLED) with CIE chromaticity coordinates of (0.35, 0.31), superior color-rendering index (Ra) of 91.5 and lower correlated color temperature (CCT) of 4,496 K was fabricated by combining a 365 nm UV-InGaN chip and a phosphor blend of yellow-emitting (Ca0.98Eu0.005Mn0.015)(9)La(PO4)(7) and blue-emitting BaMgAl10O17:Eu2+. (C) 2010 Optical Society of America
Efficient hybrid white light-emitting diodes by organic-inorganic materials at different CCT from 3000K to 9000K
(2015-04-06)
Chen, Kuo-Ju
;
Lai, Yi-Chun
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Lin, Bin-Cheng
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Lin, Chien-Chung
;
Chiu, Sheng-Huan
The hybrid white light-emitting didoes (LED) with polyfluoren (PFO) polymer and quantum dot (QD) was investigated using dispensing method at the different correlated color temperature (CCT) for cool and warm color temperature. This result indicates that the hybrid white LED device has the higher luminous efficiency than the convention one, which could be attributed to the increased utilization rate of the UV light. Furthermore, the CIE 1931 coordinate of high quality white hybrid LED with different CCT range from 3000K to 9000K is demonstrated. Consequently, the angular-dependent CCT and the thermal issue of the hybrid white LED device were also analyzed in this study. (C) 2015 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
Green-emitting phosphors and process for producing the same
(2008-10-02)
Chen, Teng-Ming
;
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
PHOSPHORS AND LIGHTING APPARATUS USING THE SAME
(2009-01-22)
Chen, Teng-Ming
;
Tai, Hsiao-Ping
A phosphor has a chemical formula of: Am(Ba1-xEux)nPyOz, wherein A is at least one of the group consisting of Li, Na and K, while 0

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