New iridium complexes with cyclometalated 2-arylimidazole ligands as highly efficient saturated green emitters.

Phosphorescence studies of a series of heteroleptic cyclometalated iridium(III) complexes have been carried out. From the photoluminescent properties, it was found that these complexes possess dominantly (3)MLCT and (3)π-π* excited states. The solvent shifts are interpreted in terms of Reichardt-Dimroth solvent E(T) parameters and Marcus theory. The results are consistent with prior assignments on the absorption band to a metal-to-ligand charge transfer excited state associated with chelating ligand. Emission kinetic studies reveal that k(r) increases with increasing λ(em) and linear correlation between ln(k(nr)) and energy gap. The effect of E(g) and ΔQ(e) on k(nr) is discussed in detail.