Electroluminescence from dysprosium- and neodymium-containing LB films

Abstract

In this paper we report on electroluminescence from Langmuir-Blodgett (LB) films of two no vel molecular complexes originally developed for non-linear optics applications containing neodymium and dysprosium trivalent rare earth ions. The two molecular complexes have a structure which consists of a donor π-π ∗ conjugated cation ionically coupled to a complex anion consisting of a trivalent rare earth ion surrounded by four singly charged pyrazolone ligands. The two materials are identical apart from the presence of either dysprosium or neodymium ions at the centre of the complex anions. LB films of the complexes produced on glass/indium tin oxide substrates produce broad electroluminescence in the visible region of the spectrum which is considerably red-shifted relative to their photoluminescence. The electroluminescent devices prepared operate in vacuo and at room temperature. The characteristic emissions associated with the rare earth ions themselves, observed as a result of photoexcitation, cannot be excited electrically.