Physicochemical studies of green phosphorescent light-emitting materials from cyclometalated heteroleptic iridium(III) complexes
摘要:
A series of novel imidazole ligands were synthesized and characterized. Phosphorescence studies of series of heteroleptic cyclometalated iridium(III) complexes reveal that these complexes possess dominantly (MLCT)-M-3 and (3)pi-pi* excited states and the solvent shifts of these complexes are interpreted by Richardt-Dimroth and Marcus solvent functions. The results consistent with prior assignments on the absorption band to a metal-to-ligand charge transfer excited state associated with chelating ligand. Emission kinetic studies exploited that the radiative transition (k(r)), increases with increasing lambda(em) and linear correlation exists between In(k(nr)) and energy gap. Electronic transition theory is applied to study the effect of E-g and Delta Q(e), on non-radiative transition (k(nr)). With a larger Delta Q(e), favouring vibrational overlap and leading to a larger value for k(nr). (C) 2011 Elsevier B.V. All rights reserved.