Novel yellowish-orange Sr₈Al₁₂O₂₄S₂:Eu²⁺ phosphor for application in blue light-emitting diode based white LED

A new yellowish-orange phosphor, Sr₈Al₁₂O₂₄S₂:Eu²⁺, was synthesized by the solid-state method and its photoluminescence properties were investigated by excitation and emission spectra. Its excitation band is extending from 400-500 nm, which is adaptable to the emission band of blue LED chips (450-470 nm). Upon the excitation of 450 nm light, the phosphor exhibits strong yellowish-orange emission centered at 605 nm with good thermal stability. A white light-emitting diode (W-LED) that consists of a blue LED chip (70 nm) and a (Sr0.92Eu0.08)8Al12O24S2 phosphor is demonstrated. The CIE1931 chromaticity coordinates (x, y) are (0.34, 0.25), the correlated color temperature (CCT) is 4300 K, and the luminous efficacy of this W-LED is 14.2 lm/W at room temperature and with a forward-bias current of 400 mA.