Hybrid Electroluminescent Devices with Atomic Layer Deposited Thin Films on a Screen Printed Dielectric

A hybrid electroluminescent (EL) device structure was developed, consisting of a screen printed Pt/Ag conductor and high-k BaTiO3 dielectric, on which a phosphor, a thin insulator and a transparent conductor were deposited by atomic layer deposition (ALD). The use of the hybrid EL structure results in more than a doubling of brightness compared with the thin-film EL alternative structure. While hybrid EL devices with ALD-grown thin-film stack deposited directly on top of a rough dielectric yield a uniform light emission, the aging stability is determined largely by the occurrence of local breakdown events due to electric field inhomogeneities originating from the combination of the rough BaTiO3/ZnS:Mn interface and the high dielectric constant of BaTiO3. Nevertheless, lifetimes of more than 600 h at 1 kHz could be obtained. 8 refs.