Luminescence properties of co-doped ZnS:Ni, Mn and ZnS:Cu, Cd nanoparticles

► Co-doped ZnS:Ni, Mn and ZnS:Cu, Cd nanoparticles were successfully synthesized. ► XRD and SAED results show the nanoparticles have good crystal quality. ► Optimum concentration of each transition metal is selected. ► Enhanced PL emission is observed for co-doped nanoparticles.