Synthesis and Spectral Properties of Eu2+-Doped Sr(S1-xSex) Phosphors for LEDs
ZHANG Xin-min1,2, WU Hao2, SU Qiang2
1. School of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha 410004, China 2. State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, China
Abstract：Eu2+-activated Sr(S1-xSex) phosphors were synthesized by solid-state reaction at high temperature. XRD patterns indicated that the phosphors are of single phase; the relationship between lattice constant and compositional ratio x is linear, in which the Vegard′s law holds. The excitation spectra are consistent with diffuse reflectance spectra, indicating that the energy absorbed by phosphor can be transferred to Eu2+ efficiently. The excitation spectra of these phosphors show broadband, extending from UV to visible light; and they can be matched with the emission wavelength of GaN chip well. The emission spectra exhibit characteristic 4f65d1→4f7 transition of Eu2+ ion. With increasing x the emission band shifted to shorter wavelength, which can be explained by the change in crystal field. The decay curve of fluorescence can be well fitted by double exponential equation, and the lifetime of Eu2+ is of the order of microsecond. The lifetimes are reasonable for the allowed 4f65d1→4f7 transition. The electroluminescence spectra of red LED manufactured with phosphors Sr(S1-xSex)：Eu2+ were measured and the parameters of them were also measured. In a word, Sr(S1-xSex)：Eu2+ are good phosphors for LED application.
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