A series of homoleptic cyclometalated iridium(III) complexes having phenylimidazole ligands were prepared to study emission properties pertinent to the phenylimidazole ligands. Ir complexes bore tris-C^N-chelated hexa-coordinated metal centers with exclusive meridional conformation: products were Ir(dmp)3, Ir(dmp-CH3)3, Ir(dmp-F)3 and Ir(dmp-CF3)3 in which phenylimidazole ligands varied in the para-position of the phenyl group with H, CH3, F and CF3 groups. Systematic emission color change was apparent within the context of electron withdrawing substituents on going from phenyl to trifluoromethyl group. Planar fused phenylimidazole ligand followed electronic control to give off most blue emission with Ir(dmp-CF3)3. Density-functional theory (DFT) calculations estimated the emissive triplet states that were closely examined by photodynamic studies. Due to the bulky planar nature of the ligand, 3MLCT was a dominant emissive origin and this ensured stability of the complexes accordingly. Device fabrication led to potency of this bulky planar ligand and device performance and ligand structure relationship will be discussed.

Photophysical studies on homoleptic phenylimidazole iridium(III) complexes: Electronic effect of planar bulky phenylimidazole ligand

253rd National Meeting (2017)

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