Enhanced red luminescence quantum yield from Gd3+/Eu3+: CaLa2ZnO5 phosphor spheres for photonic applications

Abstract

Novel bright red emission was obtained from co-doped Gd3+/Eu3+: CaLa2ZnO5 (CLZO) phosphor spheres. We have successfully synthesized co-doped Gd3+/Eu3+: CLZO phosphor spheres by citrate sol-gel method. Structural and morphological analysis was carried out by XRD and FE-SEM. EDS and XPS studies were employed to analyze the presence of elements and their ionic states respectively. The complex formation studies were carried out by the FTIR spectral study. The photoluminescence spectral profiles confirm the dazzling red emission has been observed at 626 nm (5D0 → 7F2) from the Eu3+: CLZO phosphors under the excitation of 467 nm. Upon increasing the Eu3+ concentration, the photoluminescence performance has also increased remarkably. The optimized concentration of the Eu3+ was noticed at 12 mol%. Upon co-doping with Gd3+ ions to Eu3+: CLZO phosphors, the red emission pertaining to Eu3+ was appreciably enhanced through energy transfer from Gd3+ to Eu3+ ions. The energy transfer mechanism was substantiated by several fluorescent methods such as lifetime decay dynamics and quantum efficiencies. Commission International de I’Echairage (CIE) 1931 chromaticity coordinates (x–y) calculated for singly doped and co-doped CLZO samples. The CIE coordinates were found to be (0.6644, 0.3355) and (0.6688, 0.3311) respectively, which were good consistent with the standard values of NTSC surprisingly. Correlated color temperature (CCT) value was evaluated for optimised co-doped sample and it was found to be between 2000–5000 K which could be more preferable red component for warm white light applications. The lifetime and quantum efficiency of the optimized co-doped sample have been evaluated as 1.102 ms and 69% respectively. The ravishing red emission of the Gd3+/Eu3+: CLZO phosphor spheres which suggests that these phosphor materials could be promising candidates for red luminescent optical devices.