Oxynitride/nitride phosphors for white light-emitting diodes (LEDs)

Oxynitride/nitride phosphors have attracted significant attention recently because they have promising luminescence properties and superior thermal and chemical stabilities which predestinates them for use in white LEDs to generate white light. This paper reports on luminescence spectra of Eu²⁺ or Ce³⁺-activated α-SiAlON, β-SiAlON, and alkaline earth silicon nitride (M₂Si₅N₈, M = Ca, Sr, Ba). A single broad emission band is observed for all samples, and the emission color depends on the type of activators and host lattice: α-SiAlON:Ce³⁺ (blue), α-SiAlON:Eu²⁺ (yellow), β-SiAlON:Eu²⁺ (green), and M₂Si₅N₈:Eu²⁺ (red). The excitation spectrum of these oxynitride/nitride phosphors covers a wide range from ultraviolet to visible light, enabling them to be used for white LEDs when an ultraviolet or blue LED chip is combined.