Investigation of Phosphors with High Stability for White Light Emitting Diodes
Date Issued
2009
Date
2009
Author(s)
Ke, Wei-Chih
Abstract
White light-emitting diode (WLED) are regarded as the next generation light source because of their high efficiency, long lifetimes, lower heat generation, absence of mercury, short response times and many more favorable properties. Many methods are commonly applied to generate white light. The blue LED that coated with yellow phosphor is simpler and more widely used. However, the method faces serious problems of patent issue, poor color retention and high color temperature. Another approach is to use UV LED fitted with three phosphors emitting blue, red and green, this type offers superior color uniformity with a high color rendering index and excellent quality of light.he aim of this work is to develop the phosphors based on BaMgAl10O17 and Ca2Si5N8 nitride host material, which can produce superior blue, green and red lights under excitation by UV LED. The luminescence properties and energy transfer of BaMgAl10O17:Eu, Mn were investigated. In addition, the influence of the fluxes on the luminescence, moist and thermal stability was examined. Furthermore, Ca2Si5N8:Eu, a nitride phosphor, which is produced by a solid-state reaction under ambient pressure conditions as a red phosphor. We prepared WLED by coating the synthesized blue, green and red phosphors on a UV LED chip to verify the real application capability.he characterization of the phosphors was carried out by X-ray diffraction (XRD) to study the crystal structure, and photoluminescence (PL) measurements were investigated, and the emission spectra were transformed by the program to realize their CIE color coordination and color purity. We utilized scanning electron microscope (SEM) to research their particle size and morphology. The thermal and moist stability were examined. Some results of this study are applying for one patent and submitting for one publication.
Subjects
phosphor
white light emitting diodes
Type
thesis
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