Synthesis of Highly Emissive Mn-Doped ZnSe Nanocrystals without Pyrophoric Reagents

Abstract

Manganese-doped zinc selenide quantum dots (Mn:ZnSe d-dots) with high optical quality, pure dopant emission with 40−60% photoluminescence quantum yield, were synthesized with air-stable and generic starting materials, namely zinc (manganese) fatty acid salts with corresponding free fatty acids, Se powder, fatty amine, and octadecene. The pyrophoric, highly toxic, and expensive organo-phospines were eliminated from the existing synthetic protocols for high quality Mn:ZnSe d-dots, which changed the reaction profile substantially mainly because of the enhanced reactivity of elemental Se with the presence of fatty amines. The reaction temperatures for two key processes involved in "nucleation-doping", namely, formation of MnSe nanoclusters and their overcoating by the host, were both reduced. Multiple injection techniques were employed to realize balanced diffusion of the Mn ions in the d-dots. The resulting d-dots were found to be in zinc-blende crystal structure, with optimal spherical shape, nearly monodispersed, and controlled in their Mn:Zn ratio.