Narsarsukite-structure fluorosilicate as a blue component for white LEDs: structural and optical properties

Abstract

A new blue-emitting phosphor, K2ScSi4O10F:Eu2+ (KSSOF:Eu2+), was synthesized through a solid-state reaction. The structural and optical properties of KSSOF:Eu2+ phosphor, in addition to its thermal quenching and fabrication of white LEDs (WLEDs), were investigated for the first time. The phosphor showed broad blue emission, with a maximum at similar to 434 nm under near-ultraviolet excitation due to 5d -> 4f transition of the Eu2+ ion. The critical distance was calculated to be 12 angstrom using the critical concentration of Eu2+ and Dexter's theory for energy transfer. WLEDs were fabricated by blending KSSOF: Eu2+, commercial Lu3Al5O12:Ce3+, and (Sr, Ca)AlSiN3:Eu2+ phosphors, showed a high color rendering index of 88 at a correlated color temperature of 4134 K under a forward bias current of 100 mA.