An intense green emitting LiSrPO4:Eu2+, Tb3+ for phosphor-converted LED

An intense green phosphor, LiSrPO4:Eu2+, Tb3+, was synthesized by high temperature solid-state reaction. The photoluminescence excitation and emission spectra, the lifetime and concentration effect are investigated in detail. The results show that an efficient non-radiative energy transfer from Eu2+ to Tb3+ occurs and its efficiency is about 66.4%. Tb3+ ions give an intense green emitting light by a strong excitation band of Eu2+ ions at 280–410 nm, matching well with the dominant emission band of (n)-UV (350–420 nm) LEDs. A phosphor-converted green LED was fabricated by coating the LiSrPO4:Eu2+, Tb3+ phosphor onto (n)-UV chip emitting at 370 nm. These results demonstrate that Tb3+ ion with low 4f–4f absorption efficiency in (n)-UV region can play a role of activator in narrow green-emitting phosphor potentially useful in (n)-UV GaN-based LED through efficient energy feeding by allowed 4f–5d absorption of Eu2+ with high oscillator strength.