Effect of dopant (Li+, Mg2+and Bi3+) on the photoluminescence emission intensity of Eu3+doped CaAl2O4 phosphor: Application to white LEDs

In this work, we have investigated the photoluminescence (PL) emission properties of Eu3+ doped CaAl2O4 in the presence of singly, doubly and triply ionized dopant ions i.e., Li+, Mg2+ and Bi3+ ions. The phosphor samples were synthesized by the high-temperature solid-state reaction process at 1473 K. The crystalline phase, crystallinity and surface morphology of Li+, Mg2+ and Bi3+ ions doped 0.01Eu3+:CaAl2O4 phosphor were examined and confirmed by X-Ray diffraction (XRD) and scanning electron microscope (SEM) measurements. The different vibrational groups and their corresponding vibrational frequencies were measured by Fourier transform infrared (FTIR) technique. The 0.01Eu3+:CaAl2O4 phosphor emits intense red emission at 616 nm on excitations with 393 nm (Eu3+ line) and by the charge transfer band (Eu3+-O2-) at 262 nm. The overall PL emission intensity of 0.01Eu3+:CaAl2O4 phosphor on excitation with 393 nm is found to increase almost 2.8 times in the presence of Li+ than other dopants. The emission intensity are increased in case of Li+ and Mg2+ doping due to crystallinity, charge compensation and the asymmetry created around the Eu3+ ions in the phosphors matrix. However, in case of Bi3+ ion, the emission intensity decreases on 393 nm excitation. In the presence of Bi3+ ion the intense red emission is observed due to energy transfer from Bi3+ (3P1-)1S0) to Eu3+ ion on lambda exc = 294 nm. The lifetime study were carried in each case which are in accordance with the PL emission behaviour of Li+, Mg2+ and Bi3+ ions doped 0.01Eu3+:CaAl2O4 phosphor. The CIE color coordinates, correlated color temperature (CCT) and color purity have been calculated, which shows highly pure red color in the warm light region. The 0.01Eu3+:0.10Li+: CaAl2O4 phosphor may be used in displays devices, photonic devices, solid state lighting as red light emitting source.

Automated summary

In this study, we investigated the photoluminescence emission properties of Eu3+ doped CaAl2O4 in the presence of Li+, Mg2+, and Bi3+ ions. It was found that the 0.01Eu3+:CaAl2O4 phosphor emits intense red emission at 616 nm when excited with 393 nm (Eu3+ line) and 262 nm (charge transfer band). The emission intensity is significantly enhanced in the presence of Li+ doping, while it is decreased with Bi3+ doping. Moreover, the 0.01Eu3+:CaAl2O4 phosphor exhibits highly pure red color in the warm light region.