| Summary: | 碩士 === 國立成功大學 === 電機工程學系 === 102 === In this study, Ba1-xSrxZrSi3O9:Eu2+ and Ba2MgSi2O7:Eu2+ silicate phosphors were synthesized, which could be well excited by near-ultraviolet (near-UV) lights by the solid-state reaction. The emission wavelength of the former red shifted from 477 to 483 nm with increase of Sr2+ content and the latter was at 508 nm, both of them exhibited good thermal stability with T50 〉 140oC. The external quantum efficiency of optimized Ba0.5Sr0.4ZrSi3O9:0.1Eu2+ and Ba1.94MgSi2O7:0.06Eu2+ were 44.14% and 35.64% under 405-nm excitation, respectively.
The pc-WLEDs were fabricated by the near-UV LED chips (405 nm), Ba1.94MgSi2O7:0.06Eu2+, Ba0.5Sr0.4ZrSi3O9:0.1Eu2+ and Ca2Si5N8:Eu2+ phosphors utilizing separated-layers structure (red phosphor layer was above blue and green phosphor) and the silicone gel as the remote layers. By adjusting the thickness of the phosphors to produce white LEDs of high CRI with different color temperature. The optimum luminous efficiency, C.I.E. coordinates, correlated color temperature (CCT), and CRI were 22.21 lm/W, (0.3566, 0.3582), 4606 K, and 93.8, respectively.
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