XPS study of interfaces in a two-layer light-emitting diode made from PPV and Nafion with ionically exchanged Ru(bpy)32+

Abstract X-ray photoelectron spectroscopy (XPS) was used to investigate the interfacial chemistries occurring in a prototype two-layer polymer light-emitting diode that had been fabricated from PPV and Nafion with ion-exchanged Ru(bpy) 3 2+ . Magnesium and indium tin oxide (ITO) were used as electrodes, and XPS observations were made as the different layers were added sequentially. Specifically, Mg was deposited on a layer of Nafion with incorporated Ru(bpy) 3 2+ , and this was itself deposited on PPV-coated ITO. The morphology of Nafion, which is dictated by the strongly hydrophilic and hydrophobic groups that compose it, is indicated to rearrange with the incorporation of Ru(bpy) 3 2+ ; this rearrangement appears reinforced when a thin film is deposited on PPV. The Mg deposition results in substantial changes in XPS spectra, in part due to a direct interaction with the fluorocarbon backbone of Nafion.