Optical characterization and the energy level scheme for Ce -doped BaY Si O blue-emitting phosphor.

A series of Ce -activated blue-emitting phosphors BaY Si O (BYSO) was designed and synthesized by a conventional solid-state method. Upon ultraviolet light (250-370 nm) excitation, the obtained phosphors showed an intense blue emission band centered at 400-427 nm depending on doping concentration, and corresponding to the 5d→4f transition of Ce . The effects of doping concentration on crystal structure, emitting color, photoluminescence and photoluminescence excitation spectra, as well as the concentration quenching mechanism were studied in detail. The optimal doping concentration of Ce in this phosphor was demonstrated to be about 0.75% and the concentration quenching mechanism can be ascribed to electric dipole-dipole interactions with a critical distance of ~38 Å. These fine luminescence properties indicate that BYSO:Ce may be a potential blue phosphor for full-color ultra-violet (UV) white light emitting diodes (WLEDs).