Luminescence study on Mn,Ni co-doped zinc sulfide nanocrystals.

Zinc sulfide (ZnS) doped with transition metal has been used as phosphor for various optoelectronic applications. In the present report, ZnS:Mn doped and ZnS:Mn,Ni co-doped were prepared using chemical co-precipitation method using polyvinyl pyrolidone as a surfactant. The structural studies were carried out using an X-ray diffraction technique; optical studies have been performed using ultraviolet-visible light absorption and photoluminescence (PL) spectroscopy. The presences of functional groups were confirmed using Fourier transform infrared spectroscopy. The X-ray diffraction study and Reitveld analysis confirms the formation of cubic phase with crystalline size 2-3 nm for undoped and doped ZnS nanoparticles. A novel and enhanced luminescence characteristic have been observed in PL spectra. The luminescence intensity of Mn,Ni co-doped ZnS in the blue region is much higher of that of ZnS. The PL results indicate that the doping of Ni creates shallow trap states or luminescence centres in the forbidden energy gap, which quenches the Mn states emission. Concentration quenching has been observed in Mn-doped ZnS nanoparticles. From CIE coordinates, it is seen that the yellow and blue light emission of ZnS:Mn,Ni co-doped nanophosphor may be a promising candidate for display devices and phosphor converted light-emitting diode applications.