Synthesis and characterization of new blue light emitting iridium complexes containing a trimethylsilyl group

Abstract

New blue iridium complexes with a trimethylsilyl group as a bulky electron donating group, Ir(F₂-p-trimethylsilyl)₂(fptp) and Ir(F₂-m-trimethylsilyl)₂(fptp), were synthesized via μ-chloro-bridged dimer and perfluoropropylated triazole-based ancillary ligands and then characterized using various spectroscopic studies. Both Ir(F₂-p-trimethylsilyl)₂(fptp) and Ir(F₂-m-trimethylsilyl)₂(fptp) exhibited high photoluminescence quantum efficiencies of 75 ± 5% and 76 ± 5% in films, respectively. The DFT calculation demonstrated that the new blue iridium complexes have a wide bandgap compared with FIrpic and the Ir(F₂-p-trimethylsilyl)₂(fptp) with a trimethylsilyl group in the para position has a slightly deeper HOMO level than that of the Ir(F₂-p-trimethylsilyl)₂(fptp) with a trimethylsilyl group in the meta position. The UV-vis absorption and photoluminescent (PL) spectra of the complexes were blue shifted compared with those of FIrpic. The device using the Ir(F₂-p-trimethylsilyl)₂(fptp) exhibited a maximum external quantum efficiency of 19.3% (at 0.00152 mA cm⁻²) and commission Internationale de l'Eclairage (CIE) coordinates of (0.145, 0.247).