Absorption and emission spectroscopic characterization of Ir(ppy)3

The absorption and emission spectroscopic behaviour of cyclometalated fac-tris(2-phenylpyridine) iridium(III) [Ir(ppy)(3)] is studied at room temperature. Liquid solutions, doped films, and neat films are investigated. The absorption cross-section spectra including singlet triplet absorption, the triplet-singlet stimulated emission cross-section spectra, the phosphorescence quantum distributions, the phosphorescence quantum yields and the phosphorescence signal decays are determined. In neat films fluorescence self-quenching occurs, in diluted solid solution (polystyrene and dicarbazole-biphenyl films) as well as deaerated liquid solution (toluene) high phosphorescence quantum yields are obtained, and in air-saturated liquid solutions (chloroform, toluene, tetrahydrofuran) the phosphorescence efficiency is reduced by triplet oxygen quenching. At intense short-pulse laser excitation the phosphorescence lifetime is shortened by triplet-triplet annihilation. No amplification of spontaneous emission in the phosphorescence spectral region was observed indicating higher excited-state absorption than stimulated emission. (C) 2004 Elsevier B.V. All rights reserved.