Study on the interaction between Ag and tris(8‐hydroxyquinoline) aluminum using x‐ray photoelectron spectroscopy

Abstract

Abstract In the present study, model organic light‐emitting diodes (OLEDs) with a structure of Ag/tris(8‐hydroxyquinoline) aluminum (Alq 3 )/indium tin oxide (ITO) were fabricated using vacuum evaporation and analyzed using an x‐ray photoelectron spectroscopy (XPS) depth profile technique. Diffusion of Ag into the Alq 3 layer was clearly observed. Applying a positive electron field enhanced the diffusion. Compared with pure Ag, the binding energy of diffused Ag 3d 5/2 at the interface increased slightly, and the contribution of Ag to the valence‐band spectra also was changed across the depth, implying a weak interaction between diffused Ag and the hydroxyquinoline ligands. Copyright © 2001 John Wiley & Sons, Ltd.