Synthesis and luminescence properties of a bluish-green -emitting Sr3LiSbO6: Pr3+ phosphor for optoelectronic applications

Abstract

The present work explores the significance of charge transfer band (CTB) excitation, with large absorption capacity, of Pr3+ doped Sr3LiSbO6 phosphor materials for bluish-green emission. Phosphor materials were synthesized via the conventional high-temperature solid-state method. The formation of phase structure was confirmed by XRD. The structural parameter was estimated from Rietveld refinement. Field emission scanning electron microscopy (FESEM) and High-resolution transmission electron microscopy (HRTEM) coupled with mapping and EDX spectroscopy were employed to get high-resolution images of morphologic structure. Raman and FTIR spectra were investigated to detect the presence of different vibrational levels and functional groups respectively. The elemental compositions were further confirmed via XPS survey scan spectrum and their oxidation state was also explored. The optical band-gap was found to increase first with doping concentration and then start to decrease after doping of 2 mol%, this result was further supported by photoluminescence (PL) emission spectra. PL emission spectra presented the characteristic peaks of Pr3+ due to f-f transitions. PL emission spectra illustrated that the concentration quenching took place at 2 mol% doping of Pr3+, which was governed by dipole-dipole coupling. The decay curves of each sample were recorded for specific excitation and emission wavelengths of 262 nm and 490 nm respectively. All the decay curves were well-fitted with single exponential function. The observed average decay time was 10.5 μs. Afterward, photometric studies including Chromaticity International d’Eclairage (CIE), correlated color temperature (CCT) and color purity (CP) were performed. Calculated CIE values were found to lie in bluish-green regions with lower CP and higher CCT. These results obtained from various characterizations conclude that the proposed Sr3LiSbO6 phosphor, doped with various concentrations of Pr3+ (0 mol% to 7 mol% of Pr3+), reveal their applicability in the field of solid-state lighting for white light emitting diodes.