Preparation of Sr2Si5N8:Eu2+ for white light-emitting diodes by multi-step heat treatment

In order to enhance luminescence properties of Eu2+-doped ternary nitride phosphor for white light-emitting diodes (LEDs), Sr2Si5N8:Eu2+ phosphors with different Eu2+ concentrations were synthesized using a multi-step heat treatment. Impurities and luminescence properties of prepared Sr2Si5N8:Eu2+ phosphors were investigated using X-ray diffraction (XRD) and photoluminescence spectroscopy. Excitation spectra of Sr2Si5N8:Eu2+ phosphor showed broad excitation bands by both UV and blue light. Emission peak positions in spectra were red-shifted from 613 to 671 nm as Eu2+ ion concentrations increased. Phosphors following a multi-step heat treatment showed excellent luminescence properties. These included high emission intensity and very low thermal quenching compared to measurements using a commercially available YAG:Ce3+ phosphor.

► Sr2Si5N8:Eu2+ phosphor was successfully synthesized by multi-step heating method.
► Luminescence intensity of samples was obviously improved after 2nd heat treatment.
► The optimal value of luminescence intensity was obtained at 3 h of 2nd heat treatment.
► Luminescence properties of samples were enhanced comparing with commercial YAG:Ce3+.