抄録
Darkening Phenomena of electroluminescent (EL) lamps with polyethyleneterephthalate (PET)/indium tin oxide (ITO)/ZnS:Mn/BaTiO3/Al structure has been investigated under operating in the field. The field test over one year operation changes the EL lamp surface to darken. In addition, the PET film peeled off from the underlying ITO layer. The results of Auger electron spectroscopy (AES) indicate that after the field test a sulfur-rich layer piles up at the boundary between PET and ITO films. The darken color of the film becomes disappear after etching off the most part of ITO film, then an original color of underlying ZnS:Mn layer appears. The chemical state change of the ITO and the stoichiometric change of the ZnS:Mn are also observed after the field operation of the EL lamp. The results indicate that the darkening of the EL lamp is mainly originated to a selective out-diffusion of sulfur of ZnS:Mn layer into ITO film and the chemical state change of the ITO under the EL lamp operation.
