Two-color emitting of Ce3+ and Tb3+ co-doped CaLaGa3S6O for UV LEDs

An intense bluish-green phosphor, CaLaGa(3)S(6)O:Ce(3+),Tb(3+), is developed. The photoluminescence excitation and emission spectra, the lifetime, and the concentration effect are investigated. The results show that an efficient nonradiative energy transfer from Ce(3+) to Tb(3+) occurs and its efficiency is about 11%. Although the efficiency is not high enough, these results demonstrate that a Tb(3+) ion with low 4f-4f absorption efficiency in the near-UV [(n)-UV] region can play the role of activator in a narrow green-emitting phosphor. This is potentially useful in (n)-UV (380-420 nm) GaN-based LEDs through efficient energy feeding by allowing 4f-5d absorption of Ce(3+) with high oscillator strength.