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