Photoluminescence of Cu+-doped and Cu2+-doped ZnS nanocrystallites Original Research Article

ZnS:Cu+ and ZnS:Cu2+ nanocrystallites have been obtained by chemical precipitation from homogeneous solutions of zinc, copper salt compounds, with S2− as precipitating anion formed by decomposition of thioacetamide. X-ray diffraction (XRD) analysis shows that average diameter of particles is about 2.0–2.5 nm. The nanoparticles can be doped with copper during synthesis without altering XRD pattern. However, the emission spectrum of ZnS nanocrystallites doped with Cu+ and Cu2+ consists of two emission peaks. One is at 450 nm and the other is at 530 nm. The absorptive spectrum of the doped sample is different from that of un-doped ZnS nanoparticles. Because the emission process of the Cu+ luminescence center in ZnS nanocrystallites is remarkably different from that of the Cu2+ luminescence center, the emission spectra of Cu+-doped samples are different from those of Cu2+-doped samples.