Synthesis, characterization and photophysical properties of iridium complexes with amidinate ligands

Abstract

Iridium(III) complexes containing 2-(3-fluorophenyl)-4-methylpyridine and amidinate ligands with alkyl chains were synthesized and characterized by UV/Visible, fluorescence, FTIR, NMR spectroscopies and cyclic voltammetry. Thermal properties of the iridium complexes have been investigated using thermogravimetric analysis (TGA). The influence of alkyl side groups on the photoluminescence spectra of iridium complexes has been investigated. The spectra of all complexes show similar emission which results in the blue region. However, the increase in the solution concentrations of the complexes leads to excimer emission in the amidinate complexes. The effects of different polarities of solvents on photophysical properties have been investigated. The HOMO and LUMO energy levels of the complexes are in the range of 5.32-5.35 eV and 2.48-2.51 eV, respectively. The energy states, thermal and electrochemical stability of the complexes are appropriate for their utilization in OLED applications. © 2014 Elsevier B.V. All rights reserved.