A study on photoluminescence and energy transfer of SrAlSi4N7:Eu2+, Ce3+ phosphors for application in white-light LED

• SrAlSi4N7:Ce3+, Eu2+ phosphors were prepared successfully.
• The efficient energy transfer from Ce3+ to Eu2+ in SrAlSi4N7 were confirmed.
• The energy transfer mechanism from Ce3+ to Eu2+ was proved to be dipole–dipole interaction.
• The emitting color of phosphors can be tuned based on different Eu2+/Ce3+ ratios.

A series of Ce3+- and Eu2+-coactivated SrAlSi4N7 phosphors have been synthesized by the solid-state reaction method and their luminescence properties have been investigated as a function of activator and co-activator concentrations for the first time. The energy transfer from Ce3+ to Eu2+ has been verified by directly observing the significant spectra overlap and the systematic relative intensity variation of emission bands of Ce3+ and Eu2+. The energy transfer from Ce3+ to Eu2+ has been demonstrated to be a resonant type, via dipole–dipole mechanism. The critical distance of Ce3+ and Eu2+ has also been calculated. The emitting color of phosphors can be tuned from yellow to red with increasing Eu2+/Ce3+ ratio. These results indicate SrAlSi4N7:Eu2+, Ce3+ phosphor with appropriate tuning of activator and co-activator content might be promising as an UV or blue-convertible color-tunable phosphor for white LEDs.