Computational studies of electronic structures and photophysical properties of luminescent iridium(III) complexes based on amidinate/bis(pyridylphenyl) ligands

• The structure-property relationships of Ir(III) complexes are investigated.
• The influence of substituents with different space volume is studied.
• The potential energy profiles for the thermal deactivation pathway are explored.
• Three novel Ir(III) complexes are theoretically designed.

To provide a deeply understanding of the nature of the emissive origin as well as the radiative and nonradiative processes, theoretical studies have been performed on four amidinate/bis(pyridylphenyl) iridium(III) complexes. It has been testified that they have exhibited bright yellowishgreen phosphorescence emission with moderate photoluminescence quantum yields. Besides geometries, electronic structure, absorption and phosphorescence spectra, and the factors governing the radiative decay rate constants of the emissive state have been examined. Additionally, this work also explores the potential energy profiles of the deactivation pathway via the triplet mental-centered states. Among these complexes, complex 2, which contains the bulky t-butyl group on the amidinate nitrogen atoms, presents the highest internal quantum yield. To explore more efficient phosphors, three novel phosphors, 2a, 2b, and 2c have been designed on the basis of complex 2 by incorporation of substituents on the bis(pyridylphenyl) ligand with a slightly higher quantum yield.

The geometric and electronic structures, absorption and emission spectra, phosphorescent properties as well as the potential energy profiles for the thermal deactivation pathway and the organic light-emitting diode (OLED) performance of four experimental reported and three newly designed iridium(III) complexes are theoretically investigated by means of the density functional theory/time-dependent density functional theory.Figure optionsDownload as PowerPoint slide