Novel tunable green-red-emitting oxynitride phosphors co-activated with Ce3+, Tb3+, and Eu3+: photoluminescence and energy transfer

Abstract

A series of novel Ce³⁺, Tb³⁺ and Eu³⁺ ion doped Y₄SiAlO₈N-based oxynitride phosphors were synthesized by the solid-state method and characterized by X-ray powder diffraction, scanning electron microscopy, photoluminescence, lifetimes and thermo-luminescence. The excitation of the Ce³⁺/Tb³⁺ co-doped and Ce³⁺/Tb³⁺/Eu³⁺ tri-doped phosphor with near-UV radiation results in strong linear Tb³⁺ green and Eu³⁺ red emission. The occurrence of Ce³⁺–Tb³⁺ and Ce³⁺–Tb³⁺–Eu³⁺ energy transfer processes is responsible for the bright green or red luminescence. The Tb³⁺ ion acting as an energy transfer bridge can alleviate MMCT quenching between the Ce³⁺–Eu³⁺ ion pairs. The lifetime measurements demonstrated that the energy-transfer mechanisms of Ce³⁺ → Tb³⁺ and Tb³⁺ → Eu³⁺ are dipole–quadrupole and quadrupole–quadrupole interactions, respectively. The temperature dependent luminescence measurements showed that as-prepared green/red phosphors have good thermal stability against temperature quenching. The obtained results indicate that these phosphors might serve as promising candidates for n-UV LEDs.