Characterization of ZnS:Cu, Br electroluminescent phosphor prepared by new route

Synthesis of electroluminescent ZnS:Cu, Br phosphor by a number of routes has been presented along with their brightness-voltage, brightness-frequency, brightness-waveform and spectral energy distribution studies. The sample fired in N-2 atmosphere with aluminum and bromine shows predominantly green emission with a peak around 530 nm whereas the sample prepared under H2S and HBr shows the broadest emission spectrum with multiple peaks. These peaks may arise out of different possible bands of copper, self-activated luminescence of ZnS and association of copper with some of the donor levels formed because of the higher reactivity of HBr. All the samples have been found to obey the relation B = B-0 exp.(-b/V-0.5) which has been discussed using bipolar tunnel emission model. The frequency variation of brightness is linear. Samples containing bromine show multiple secondary peaks indicating that bromine helps in formation of multiple shallow traps. (C) 2002 Elsevier Science Ltd. All rights reserved.