Semiconductor nanoparticles of ZnS:Co are synthesized by
wet chemical method at room temperature. The effects of increasing cobalt
ions dopant in PL ZnS particles are studied, and the distribution,
absorption, excitation, emission, and structural properties of particles
have been determined. XRD investigation shows the cubic structure of ZnS
nanoparticles and doping has no effect on the structure and the average
crystalline particle size of the doped and undoped ZnS nanometerscale
samples is about 2.5 nm. TEM shows the 1–3 nm size for ZnS:Co
nanoparticles. UV-visible is used to study the optical absorption of ZnS
pure as well as doped nanoparticles. Furthermore, as the chemical parameters
change, the size of quantum dots changes systematically. Of course, doping
percentage is a significant parameter in photoluminescence properties of
quantum dots, but it has no effect on the size. The maximum intensity of
photoluminescence spectra obtains the at 0.1% molar of the Co dopant in
ZnS:Co (Ex = 283, Em = 485.423 nm) that shows the quenching point. The
intensity of the emission bands decreases with the increasing of the doping
percentage continuously, which indicates that cobalt ions are the
eliminators of the photoluminescence.