Electroluminescence of a ZnS-based powder phosphor

Electrouminescence (EL) and photoluminescence (PL) spectra of carbon nanotube (CNT) incorporated ZnS:Cu,Al inorganic powder phosphors under an AC voltage were analyzed by comparing with bare ZnS:Cu,Al powder. The spectra was obtained at room temperature with a He-Cd laser and a single grating monochrometer. By varying the frequency of the applied ac voltage, the PL and EL spectra yield distinct difference in the peak position, width, and intensity of the luminescence. As the concentration of CNTs were increased, the separation between the two luminescence peaks, which were analyzed by the Gaussian fitting, shrank. However, the spectra showed little different behavior for the voltage variation at fixed frequency. The underlying mechanism for this frequency dependence on CNT incorporation and EL performance enhancement will be mentioned in this poster.