Shell thickness dependence of luminescence intensity in core/shell ZnS:Mn/ZnS nanoparticles

In the present work, ZnS-coated ZnS:Mn nanoparticles were synthesized and the ZnS shell thickness dependence of Mn emission intensity was investigated. X-ray diffraction (XRD) measurements showed that both the ZnS:Mn nanoparticles and the ZnS shells possessed a zinc blende structure. Transmission electron microscopy (TEM) images and the quantum confinement effect shown in room temperature photoluminescence excitation (PLE) spectra gave the direct evidence that ZnS shells have been successfully coated on the ZnS:Mn nanoparticles. The room temperature photoluminescence (PL) spectra revealed an increase in the Mn emission intensity followed by a steady decline as the ZnS shells thickened. The effect of ZnS shells on the luminescence properties of ZnS:Mn nanoparticles is discussed.