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

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 similar 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 degrees C in a crude solution.