Ce3+-activated CaSr2Al2O6 green-emitting phosphors: Potential application as color converter for warm WLEDs

Abstract

In this work, green-emitting Ce3+-activated CaSr2Al2O6 (CSA) phosphors were successfully synthesized by solid-state reaction at high temperature and their phase purity, crystal structure, morphologies, photoluminescence properties, as well as the thermal stability were also investigated at length. The CSA:Ce3+ phosphors exhibited an intense broad green emission band in the 450–650 nm range centered at 545 nm under 375 nm near-ultraviolet light excitation. The full width at half maximum was about 94 nm. And the optimal doping concentration of Ce3+ ions in Ca1-xSr2Al2O6:xCe3+ was x = 0.01 (namely, 1 mol%). The CIE chromaticity coordinates of CSA:0.01Ce3+ samples were calculated to be (0.3553, 0.5541) with the corresponding internal quantum efficiency determined to be about 31%. Besides, the CSA:0.01Ce3+ phosphors possessed a high thermal stability. The green emission showed slight blue-shift at high-temperature, while its emission intensity at 423 K still maintained 71.3% of the initial value at 303 K. A prototype white light-emitting-diode (LED) lamp with a superb color rendering index (CRI = 92) and a low correlated color temperature (CCT = 3671 K) was successfully fabricated by combining a 365 nm near-ultraviolet-emitting LED chip with the CSA:0.01Ce3+ as a green component, BaMgAl10O17:Eu2+ as a blue component, and CaAlSiN3:Eu2+ as a red component.