Modeling of ZnS quantum dots synthesis by DFT techniques

Zinc sulfide (ZnS) and doped zinc sulfide (ZnS:Cu) were prepared by the polyol process using polyethylene glycol (PEG) as the ceramic precursor. Thiourea (TU) was employed for in situ generation of ZnS ceramic powder. X-ray diffraction (XRD), scanning electron microcopy (SEM), absorption and photoluminescence (PL) spectra were used to characterize the luminescent ceramic. The structure, surface morphology, chemical composition and optical properties of the inorganic phosphors were investigated as function of copper doping. Both XRD and SEM indicated that the particles present good crystalline state, whose crystalline grain sizes were in the range around 50–60 μm. The reactivity of both, PEG:Zn2+ and PEG:Zn2+:TU was interpreted by means of the potential energy surfaces determined by density functional theory (DFT) computations. The analysis of the local ionization surfaces and frontier orbitals was used to study the reactivity of the PEG:Zn2+:TU as ZnS nanocrystals precursor.