Organic electroluminescence devices fabricated with chemical vapour deposited polyazomethine films

Abstract

We demonstrate the use of chemical vapour deposition polymerization as an effective method to fabricate conjugated polymer films as constituents in organic electroluminescence (EL) devices. This technique provides excellent compatibility with vacuum sublimation deposition of low molecular weight materials for construction of hybrid devices. The specific polyazomethine polymer studied here, namely, poly(1,4-phenylenemethylidynenitrilo-1,4-phenylenenitrilomethylidyne), is shown to be an addition to the range of polymer structures that provide electron transport functionality and, in combination with suitable emissive materials, provides the basis for new device structures. From measurements on a series of devices we propose an energy level structure for this material. Despite remaining isoelectronic with poly (1,4-phenylenevinylene) the energy levels of the polyazomethine are strongly shifted through the replacement of a vinylene CH with a N atom.