Mn2+-doped Zn–In–S quantum dots with tunable bandgaps and high photoluminescence properties

Abstract

In the present work, we reported the synthesis of Mn²⁺-doped Zn–In–S quantum dots (QDs) with high optical performance in a controlled manner. The effects of the temperature, the introduced ODE-S amount and Zn/In ratios in the raw materials, as well as the Mn²⁺ doping concentrations on the photoluminescence (PL) properties of Mn²⁺-doped Zn–In–S QDs were investigated systematically. The resultant QDs exhibit tunable bandgaps ranging from 2.9 to 3.7 eV, well-resolved Mn²⁺ d–d emission with a PL quantum yield (QY) of 56% and a surprisingly long excited state lifetime up to ∼4.2 ms, suggesting their excellent PL properties. Meanwhile, the initial high PL QY of the obtained Mn²⁺-doped Zn–In–S QDs in organic solvents could be preserved very well once they were transferred into aqueous media via ligand exchange. Furthermore, the as-synthesized QDs exhibit excellent thermal stability up to 200 °C in a crude solution.