Optical properties of undoped and cobalt doped ZnS nanophosphor

In the present study, the optical properties of ZnS and cobalt (Co) doped ZnS nanoparticles were investigated at room temperature. ZnS and ZnS:Co nanophosphors were prepared through chemical route, namely the chemical precipitation method and the formation of the nanoparticles were confirmed by X-ray diffraction and field emission scanning electron microscope (FESEM). Band gap energy of the prepared samples is determined by using a UV-vis-NIR spectrophotometer. The photoluminescence property of ZnS and ZnS:Co sample is determined by fluorescence spectroscopy. The sizes of as prepared nanoparticles are found to be in the 8-9 nm range. The FESEM morphology shows the formation of nanostructure of ZnS samples. The value of optical band gap has been found to be in the range 4.30-4.03 eV. Room temperature photoluminescence (PL) spectrum of the undoped sample exhibits emission in the blue region with multiple peaks under UV excitation. On the other hand, Co²⁺ doped ZnS samples show enhanced visible light emissions under the same UV excitation wavelength of 310 nm.