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Spectra and kinetics of SnOx-ZnS-CuxS-ZnS:Mn-Al electroluminescent cells were investigated for different dc voltage applied. Both zinc sulphide films and aluminum films were produced by thermal evaporation in a vacuum of about 10-5Tr. The thin tin oxide films were prepared by spray technique, based on the pyrolysis of an aerosol on the surface of heated glass substrate. The CuxS layer was made by wet chemical process. The cells exhibit yellow-orange emission with a maximum at about 585 nm. Kinetic measurements indicate that the decay curve of the electroluminescence can be usually expanded in two exponentials. These exponentials are due to two kinds of manganese centers: Mn2+ ions with longer lifetime t1 and Mn2+-Mn2+ pairs with shorter lifetime t2. The values of the lifetimes depend on manganese concentration, temperature and types of crystal sites. The lifetimes are rather shorter for thin films and longer for crystals and powder phosphors. When a short voltage pulse is supplied to the cells, the maximum of the electroluminescence appears after the end of the exciting pulse. The phenomenon can be explained assuming energy transfer from one monomolecular center to another. The electroluminescence spectra were measured for several applied voltages from 18 to 100V. It was found that the spectrum becomes broader for higher voltages, mainly on the short-wavelength side of the spectrum. Additionally, the voltage dependence of the manganese lifetimes was investigated. The values of the lifetimes are longer for higher voltages.
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