Correlation of Structure, Tunable Colors, and Lifetimes of (Sr, Ca, Ba)Al₂O₄:Eu²⁺, Dy³⁺ Phosphors

(Sr, Ca, Ba)Al₂O₄:Eu²⁺, Dy³⁺ phosphors were prepared via a high temperature solid-state reaction method. The correlation of phase structure, optical properties and lifetimes of the phosphors are investigated in this work. For the (Sr, Ca)Al₂O₄:Eu²⁺,Dy³⁺ phosphors, the different phase formation from monoclinic SrAl₂O₄ phase to hexagonal SrAl₂O₄ phase to monoclinic CaAl₂O₄ phase was observed when the Ca content increased. The emission color of SrAl₂O₄:Eu²⁺, Dy³⁺ phosphors varied from green to blue. For the (Sr, Ba)Al₂O₄:Eu²⁺, Dy³⁺ phosphors, different phase formation from the monoclinic SrAl₂O₄ phase to the hexagonal BaAl₂O₄ phase was observed, along with a shift of emission wavelength from 520 nm to 500 nm. More interestingly, the decay time of SrAl₂O₄:Eu²⁺, Dy³⁺changed due to the different phase formations. Lifetime can be dramatically shortened by the substitution of Sr²⁺ with Ba²⁺ cations, resulting in improving the performance of the alternating current light emitting diode (AC-LED). Finally, intense LEDs are successfully obtained by combining these phosphors with Ga(In)N near UV chips.