Crystal structure, optical spectroscopy and energy transfer properties in NaZnPO4:Ce3+, Tb3+phosphors for UV-based LEDs

A new series of Ce3+, Tb(3+)singly doped and Ce3+/Tb(3+)co-doped NaZnPO4(NZPO) phosphors have been synthesizedviaa high-temperature solid-state reaction method at 800 degrees C. The crystal cell structure, luminescence proprieties, energy transfer, and chromaticity coordinates of the as-prepared phosphors were investigated in detail. The photoluminescence spectra of NZPO:Ce(3+)phosphors exhibited broad emission in the 300-380 nm range, while under UV excitation, the singly doped NZPO:Tb(3+)phosphor showed emission peaks at similar to 485-690 nm among which the green emission peak appears at similar to 543 nm. The Tb(3+)green emission was significantly enhanced almost 20 timesviaenergy transfer from Ce(3+)to Tb3+. The energy transfer (ET) mechanism from Ce(3+)to Tb(3+)in NZPO is identified to be a resonant typeviathe dipole-dipole interaction mechanism with an ET efficiency of 91%. Intense green emission is obtained at very low Tb(3+)concentrations under 285 nm excitation, making NZPO:Ce3+/Tb(3+)an efficient UV-excited green phosphor. The NaZnPO4:Ce3+/Tb(3+)phosphors are promising UV convertible materials of green light for UV -LEDs applications.