Photoluminescence properties of Eu 2+ doped Ba 2ZnS 3 phosphor for white light emitting diodes

Abstract

The synthesis and photoluminescence properties of novel Eu 2+ doped Ba 2ZnS 3 phosphors for white light emitting diodes (LEDs) are reported. Diffuse reflection spectra of Ba 2ZnS 3 host and synthesized phosphors have been measured. The excitation spectra of synthesized phosphors consist of three broad bands between 250 nm and 550 nm and are consistent with the diffuse reflectance spectra. The emission spectra show the characteristic 4f 65d 1 → 4f 7 transition of Eu 2+ ion and there exists efficient energy transfer from host to Eu 2+ ions when excited by 350-nm light. The dependence of emission spectra on temperature is also measured; the possible reasons applied to explain the experimental results are also discussed. The fluorescence lifetime of Eu 2+ in Ba 1.995ZnS 3:0.005Eu 2+ is measured and the values are 1.49 and 23.4 μs.