The ZnS:Cu, Al phosphor has been studied for low voltage excitation field emission devices. To improve the cathodoluminescence (CL) brightness, the phosphor has been synthesized with iodide-type alkaline and alkali-earth metal as fluxes. Cut and AlF3 were used as an activator and coactivator, respectively. The phosphor has been characterized in comparison with commercially available cathode ray tubes (CRTs) phosphor and conventionally prepared ones. Newly synthesized ZnS:Cu, Al phosphor prepared with iodide-type fluxes has shown higher CL brightness than commercially available phosphor and conventionally prepared ones. The phosphor structure has been analyzed using scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. From the analysis, the phosphor particles were composed of cubic and hexagonal phases. The cubic phase was much more formed when iodide-type fluxes were used. This cubic phase helps the phosphor to have high brightness at low voltage operations.