Tunable luminescence of Na3YSi3O9:Ce3+, Mn2+ via efficient energy transfer for white LEDs

Ce3+ and Mn2+ co-doped Na3YSi3O9 (NYS) phosphors with tunable emission were prepared via a high-temperature solid-state reaction. Under 320-nm excitation, Na3YSi3O9:Ce3+, Mn2+ exhibits two broad emission bands from 340 to 590 nm and from 525 to 700 nm, ascribed to the 5d-4f transition of Ce3+ and the T-4(1)((4)G)-(6)A(1)(S-6) spin-forbidden transition of Mn2+, respectively. Energy transfer from Ce3+ to Mn2+ through a dipole-dipole interaction was explained based on the luminescence spectra and fluorescence decay curves. The critical distance of energy transfer was calculated to be 12.836 angstrom, and the energy transfer efficiency reached as high as 91.9%. Temperature-dependent luminescence was studied, and the corresponding activation energy Delta E was calculated to be 0.221 eV. Tunable luminescence from blue to orange was realized utilizing the energy transfer from Ce3+ to Mn2+. A warm white light with CIE chromaticity coordinates of (0.3627, 0.2855) and color temperature of 3612 K was achieved. These results indicate that NYS:Ce3+, Mn2+ may have potential application in UV-pumped white-light-emitting diodes.