Enhanced photoluminescence and characterization of Mn-doped ZnS nanocrystallites synthesized in microemulsion

Abstract

ZnS:Mn luminescent nanomaterials were first prepared in an inverse microemulsion at room temperature as well as under a hydrothermal condition. Mn-doped ZnS nanoparticles obtained are distributed from 3 to 18 nm in diameter as determined by transmission electron microscopy. The crystalline nature of the materials is clearly demonstrated by the X-ray diffraction results. Compared with Mn-doped ZnS materials synthesized through the conventional aqueous reaction, the nanoparticles prepared in a microemulsion show a significant enhancement in photoluminescence. In particular, the photoluminescence of particles prepared in microemulsion under hydrothermal treatment was found to be enhanced by a factor of 60 as compared to that of the material obtained through the direct aqueous reaction at room temperature. This dramatic increase in photoluminescence yield is attributed to the surface passivation of nanoparticles by the adsorption of surfactants in microemulsion, the formation of sphalerite with cubic zinc blende structure, and Mn migration into the interior lattice of ZnS host.