Microwave assisted synthesis of ZnS quantum dots using ionic liquids

In this work we report results from microwave (MW) assisted synthesis of highly crystalline ZnS quantum dots (QDs) using ionic liquid (ILs) as MW absorbing medium. Two types of ionic liquids, imidazolium and phosphonium based, were used. The QDs are less than 5 nm in size and of wurtzite ZnS type, as characterized by high-resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED) pattern. The optical properties were investigated by UV–vis absorption and show a blue shift in absorption as compared to bulk wurtzite ZnS due to quantum confinement effects. The photoluminescence (PL) spectra of the QDs show different trap state emissions.

► Highly crystalline wurtzite ZnS QDs were synthesized using ILs as MW absorbing medium.
► Both inorganic and organic compounds were used as Zn and S Sources.
► Two types of ionic liquids, as imidazolium and phosphonium based, were used.
► ILs act as high MW absorber, stabilizer and designer solvents.
► The approach used is a green chemical route involving principles of Green Chemistry i.e. design of safer nanomaterials, materials and energy efficiency, process safety.