Synthesis and Photoluminescence of Nanocrystalline ZnS:Mn²⁺

The influence of the synthesis conditions on the properties of nanocrystalline ZnS:Mn 2+ is discussed. Different Mn 2+ precursors and different ratios of the precursor concentrations [S 2- ]/[Zn 2+ ] were used. The type of Mn 2+ precursor does not have an effect on the luminescence properties in the synthesis method described. On going from an excess of [Zn 2+ ] to an excess of [S 2- ] during the synthesis, the particle diameter increases from 3.7 to 5.1 nm, which is reflected by a change in the luminescence properties. Photoluminescence measurements also showed the absence of the ZnS defect luminescence around 450 nm when an excess [S 2- ] is used during the synthesis. This effect is explained by the filling of sulfur vacancies. The ZnS luminescence is quenched with an activation energy of 62 meV, which is assigned to the detrapping of a bound hole from such a vacancy.