Luminescence properties of Mn4+-doped CaAl2O4 as a red emitting phosphor for white LEDs

Abstract

A series of Mn4+-activated CaAl2O4 (CAO) compounds were synthesized by co-precipitation to seek a candidate for a red-emitting phosphor to be employed in a white LED. The crystal structure, morphology, and fluorescence properties of the as-obtained phosphors were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL). The deep red luminescence of Mn4+ in CaAl2O4 is reported and discussed. The excitation spectrum exhibited broadband emission between 260 and 550 nm with three peaks dominating at 320 nm due to the transition of 4A2->4T1. The emission spectra between 600 to 720 nm displays an overwhelming emission peak at 654 nm owing to the 2E->4A2 transition of Mn4+ ion. This research demonstrates the great promise of CaAl2O4:Mn4+ as a commercial red phosphor in warm white LEDs and opens up new avenues for the exploration of novel non-rare-earth red-emitting phosphors.

Keywords

• CaAl2O4:Mn4
• co-precipitation
• phosphors