Luminescence properties of (Ca1−xSrx)Se:Eu2+ phosphors for white LEDs application

Novel phosphors of Eu2+-doped (Ca1−xSrx)Se for the application of white light emitting diodes (LEDs) were prepared by conventional solid-state reaction. Diffuse reflection spectra of CaSe, SrSe, CaSe:Eu2+ and SrSe:Eu2+ were measured. The excitation spectra consisted of two broad bands and were consistent with the diffuse reflectance spectra. The emission band is due to the 4f65d1→4f7 transition of the Eu2+ ion. With an increase in x, the emission band shifted to shorter wavelength and the reason was discussed. The fluorescence lifetimes of Eu2+ in (Ca1−xSrx)Se:0.04Eu2+ were also measured and the values were reasonable for the allowed transition 4f65d1→4f7 in Eu2+.