Photoluminescence Properties and White Light Emitting Diodes Applications of NaYSiO4∶Ce3+Blue Phosphor
A series of NaYSiO4∶x Ce3+(0.01≤x≤0.05)blue phosphors were synthesized by high-temperature solid-state reaction method.NaYSiO4∶x Ce3+phosphors have a broadband absorption in the 250-360 nm region,which can be well matched with ultraviolet(UV)LED chips.There exist multiple Ce3+luminescence centers in the NaYSiO4∶x Ce3+phosphors,which exhibits a broadband blue emission with peak wavelength near 414 nm under UV excitation.Measured across the UV region(300-350 nm),the quantum efficiencies of NaYSiO4∶0.02Ce3+phosphor can remain larger than 25%.The NaYSiO4∶0.02Ce3+phosphor shows excellent chemical stability,and its emission intensity and quantum efficiency were almost unchanged after being soaked in water for 14 days.The observed significantly spec-tral blue-shift and rapidly reduced half-maximum full width(FWHM)in the temperature-dependent emission spectra of the NaYSiO4∶0.02Ce3+sample can be attributed to the thermally activated phonon-assisted tunneling effect.A bright white light emitting diodes(WLED)with a color rendering index of 95 can be fabricated by depositing the NaYSiO4∶0.02Ce3+blue phosphor,commercial(Sr,Ba)2SiO4∶Eu2+green phosphor and commercial(Ca,Sr)AlSiN3∶Eu2+red phosphor on 310 nm UV LED chip.When the drive current gradually increases from 50 mA to 300 mA,the fabricated LED device shows a stable warm-white light emission with almost unchanged color coordinates.These re-sults indicate that NaYSiO4∶0.02Ce3+blue phosphor reported here has a potential application in UV LED chip pumped WLED lighting.
NaYSiO4∶Ce3+high-temperature solid-state reaction methodblue phosphorwhite light emitting di-odeshigh color rendering index
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