Regulating vibrational modes to improve quantum efficiency: insights from theoretical calculations on iridium(iii) complexes bearing tridentate NCN and NNC chelates

Abstract

We reported a theoretical study on [(NCN)Ir(III)(NNC)]⁺ tridentate Ir(III) complexes for organic light-emitting diode (OLED) applications. With appropriate chemical modifications onto the NCN ligand of [(NCN)Ir(III)(NNC)]⁺, several rotational and stretching vibration modes were weakened or even eliminated, resulting in a weaker vibrational coupling between the emissive state and the ground state, therefore slowing down the non-radiative decay process, ultimately improving the quantum efficiency. We hope that these theoretical studies and the semi-quantitative prediction on phosphorescence efficiency could provide inspiration for the design of highly efficient phosphorescent materials.