Stability of tris(8-hydroxyquinoline)-aluminum(III) films investigated by vacuum ultraviolet spectroscopic ellipsometry -: art. no. 111907

The optical constants of tris(8-hydroxyquinoline)-aluminum(III) (Alq(3)) thin films were determined in the vacuum ultraviolet range up to 9.5 eV by in situ spectroscopic ellipsometry measurements performed using synchrotron radiation. The exposure to atmosphere of the Alq(3) films grown by organic molecular-beam deposition induces changes in ellipsometric spectra that are interpreted in terms of surface morphology changes. Alq(3) films deposited by organic vapor phase deposition were found to be more stable upon exposure to atmosphere. Employing time-dependent density functional theory calculations, the features of the extinction coefficient were assigned to singlet-singlet transitions. (C) 2005 American Institute of Physics.