Synthesis and photoluminescence of Eu³⁺ and O^2- co-doped ZnS nanoparticles with yellow emission synthesized by a solid-state reaction

ZnS:Eu, O nanoparticles were synthesized by a solid-state reaction at 90 °C for the first time. The effect of Eu³⁺ and O^2- co-doping on the photoluminescence (PL) of the samples was researched. X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectrum (EDS), ultraviolet-visible diffusion reflection spectra, and PL spectra were used to characterize their crystal structure, chemical compositions, diameter, and PL properties. The results showed that all nanoparticles had a cubic blende crystal structure and an average crystallite size of 3.3–4.0 nm. Besides the emission from the ZnS host, typical luminescence of Eu³⁺ was all observed in the emission spectra of ZnS:Eu, O nanoparticles, and ZnS:Eu, O nanoparticles showed yellow emissions under 464 nm excitation. The PL intensity remarkably increased with the increase of O^2- concentration, and the maximum emission with correlated color temperature ~ 2419 K was obtained in the ZnS:1% Eu, 5% O sample, and about 2.75 times stronger than the undoped ZnS nanoparticles. Mechanism for the enhanced luminescence was discussed. This work suggests that Eu³⁺ and O^2- co-doped ZnS nanoparticles prepared by the low temperature solid-state reaction method can be used for Light-Emitting Diodes.