Structural and luminescence characterization of thermally stable orange-red emitting LiSrP3O9:Sm3+ phosphor to fill the amber gap in WLEDs

Abstract

Orange-red light emitting LiSr(1-x)P3O9:xSm3+ phosphors were successfully prepared by the Solution combustion method. The Powder X-ray Diffraction analysis confirmed a single phase for the samples with a crystallite size ranging from 66 ± 0.9 nm to 72 ± 0.5 nm. The photoluminescence (PL) spectra revealed that at 398 nm excitation, the LiSrP3O9:Sm3+ phosphors could be easily excited and displayed a bright orange-red emission which attributes to 4G5/2 → 6H7/2 transition of dopant (Sm3+) ion. At 398 nm excitation, the optimum PL intensity was obtained for the 2 mol% Sm3+ ion-doped sample. The lifetime decay measurements showed that the lifespan decreased steadily from 3.48311 to 2.98869 ms with an increase in the Sm3+ ion concentration. Commission International de l'Eclairage coordinates (0.58, 0.42), which correspond to a strong orange red emission situated in the amber gap, colour purity (97.73%), and colour correlated temperature (1666 K) demonstrated excellent luminescent performance. To assess the thermal stability of the phosphor, the thermal quenching behavior of its PL emission was investigated. These results indicate that the LiSrP3O9:Sm3+ phosphor might be a viable option for filling the amber gap in light-emitting diodes.