Luminescent properties and energy transfer of CaO:Ce3+, Mn2+ phosphors for white LED

We have synthesized yellow-orange CaO:Ce3+,Mn2+ phosphors by solid-state reaction. Photoluminescence properties and energy transfer mechanism from Ce3+ to Mn2+ ions have been investigated. The Ce3+ activated phosphors exhibit strong absorption in the range of 250-490 nm and a yellow emission centered at 554 nm. When Mn2+ ions were codoped, CaO:Ce3+,Mn2+ phosphors exhibit yellow emission band of Ce3+ as well as orange emission band centered at 600 nm of Mn2+. We observed an efficient energy transfer from Ce3+ to Mn2+ ions in CaO:Ce3+,Mn2+, which was verified from the lifetime decay curves and was discussed by Dexter׳s energy transfer theory. The critical distance of the energy transfer from Ce3+ to Mn2+ ions has also been calculated to be 12.3 Å by spectral overlap methods following Dexter׳s theory and by concentration quenching mechanism to be 15.2 Å. Moreover, by combining the synthesized phosphors and InGaN blue chip (460 nm), warm-white light has been created.