Blue to bluish-green tunable phosphor Sr₂LiSiO₄F:Ce³⁺,Tb³⁺ and efficient energy transfer for near-ultraviolet light-emitting diodes

Ce³⁺ and Tb³⁺ activated Sr₂LiSiO₄F phosphors were prepared by a solid state reaction technique at high temperature, and their ultraviolet (UV)-visible spectroscopic properties were investigated. Under ultraviolet light excitation, Ce³⁺-doped Sr₂LiSiO₄F phosphors emit blue light (420 nm), while Tb³⁺-doped phosphors show yellowish green emission. Efficient energy transfer from Ce³⁺ to Tb³⁺ ions in co-doped samples was confirmed in terms of corresponding excitation and emission spectra. The energy transfer mechanism between Ce³⁺ and Tb³⁺ was discussed and demonstrated to be dipole–dipole interaction in Sr₂LiSiO₄F:Ce³⁺,Tb³⁺ phosphors. Due to energy transfer from Ce³⁺ to Tb³⁺, Ce³⁺ and Tb³⁺ co-doped Sr₂LiSiO₄F phosphors show intense absorption in near-UV region, and present tunable emission from blue to bluish green under 360 nm light excitation. The results indicate that these phosphors can be considered as candidates for white LEDs pumped by n-UV chips. (paper)