Several Blue-Emitting Thin-Film Electroluminescent Devices

Abstract

Blue-emitting thin-film electroluminescent (EL) devices were studied. As the blue-emitting phosphor, thin-films in which the Tm 3+ ion was doped into several hosts (ZnS, Y 2 O 2 S, CdF 2 , ZnF 2 and YF 3 ) and CaF 2 :Eu were investigated. Blue EL emission of Tm 3+ ions arising from the 1 D 2 → 3 H 4 or 1 G 4 → 3 H 6 transition was observed in each Tm-doped device. The most dominant lines in these emissions varied with the kind of host materials. The CaF 2 :Eu thin-film also showed blue electroluminescence due to a parity-allowed 4f 6 ( 7 F)5d→4f 7 ( 8 S) transition of the Eu 2+ ion.