Electroabsorption study of metal-to-ligand charge transfer in an organic complex of iridium(III)

The dipole moment and polarizability changes have been determined from electroabsorption (EA) spectroscopy of solid films of fac tris(2-(phenyl)pyridinato,N,C-2')iridium (III) [Ir(ppy)(3)]. The maximum changes in the dipole moment \Deltamu\(s) = (5.0 +/- 0.5) D/f (f is the local field correction factor: 1.3-1.7) accompany ground state to the lowest singlet, and \Deltamu\(T) = (1.7 +/- 0.5) D/f ground state to the lowest triplet metal-to-ligand charge transfer (MLCT) excited states formation, while the average polarizability change Deltap = (20 +/- 5) Angstrom(3)/f(2) follows from the fitting procedure throughout the visible absorption spectrum range. The experimental values of \Deltamu\ as well as energy positions of the MLCT states correlate with the literature results of time-dependent density functional theory. (C) 2004 Elsevier B.V. All rights reserved.