White-electroluminescent device with ZnS:Mn, Cu, Cl phosphor

White-light-emitting ZnS:Mn, Cu, Cl phosphors with the double phases of cubic and hexagonal structures are successfully synthesized by varying the dopants concentrations. They are applied to the powder alternating currents (AC) electroluminescent (EL) devices through the silk screen method: electrode/BaTiO3 insulator layer/ ZnS:Mn, Cu, Cl phosphor layer/ ITO PET substrate. The powder AC EL devices show the white light of three emission peaks. As Mn and Cu ions increase, the blue and green intensities decrease whereas the yellow intensity increases. It is due to the energy transfer from the blue and green bands to the yellow band. As applied voltage increases, the blue and the yellow bands also increase at the same rate. Also the blue Cu-related and the yellow Mn2+ emission intensities are saturated at higher frequency due to the depletion of the excitable electrons of Mn2+ ions with longer decay time of order of millisecond.