Colloidal Manganese-Doped ZnS Nanoplatelets and Their Optical Properties

Manganese (Mn)-doped ZnS nanocrystals (NCs) have been extensively explored for optical applications with the advantages of low toxicity, large Stokes shifts, and enhanced thermal and environmental stability. Although numerous studies on Mn-doped ZnS dots, rods, and wires have been reported, the literature related to Mn-doped ZnS nanoplatelets (ZnS:Mn NPLs) is scarce. Here, we present the first example of direct doping of Mn2+ ions into ZnS NPLs via the nucleation-doping strategy. The resulting ZnS:Mn NPLs exhibit Mn luminescence, indicative for successful doping of the host ZnS NPLs with Mn2+ ions. The energy transfer from the ZnS NPLs to the Mn2+ ions was observed by employing spectroscopic methods. Furthermore, the impact of the Mn concentration on the optical properties of ZnS:Mn NPLs was systematically investigated. As a result of Mn-Mn interaction, tunable Mn emission and shortened photoluminescence (PL) lifetime decay were observed and rationalized by means of electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS). Finally, we show that the initially low dopant PL quantum yield (QY) of ZnS:Mn NPLs can be dramatically enhanced by passivating the surface trap states of the samples. The presented synthetic strategy of ZnS:Mn NPLs opens a new way to synthesize further doped systems of two-dimensional (2D) NPLs.

Automated summary

This study presents the successful direct doping of Mn2+ ions into ZnS nanoplatelets using a nucleation-doping strategy, resulting in Mn luminescence in ZnS:Mn NPLs. Energy transfer from ZnS NPLs to Mn2+ ions was observed, and the impact of Mn concentration on optical properties was systematically investigated. Tunable Mn emission and enhanced PL quantum yield in ZnS:Mn NPLs were achieved by passivating surface trap states. The synthetic strategy introduced here opens up new possibilities for further doped systems of two-dimensional NPLs.