Sébastien Ladouceur

Bright electrochemiluminescence of iridium(III) complexes

Electrochemiluminescence (ECL) of four bright iridium(III) complexes containing aryltriazole cyclometallated ligands is reported. The ECL mechanisms, spectra and high efficiencies via annihilation and coreactant paths have been investigated.

Self-Enhanced Electrochemiluminescence of an Iridium(III) Complex: Mechanistic Insight**

Improved luminophore: The electrochemiluminescence (ECL) of an iridium complex self-enhanced up to 16 times is reported. Three excited states were observed in the emission spectra (see picture). The ECL efficiency of this complex is the highest reported for an iridium complex.

High stability light-emitting electrochemical cells from cationic iridium complexes with bulky 5,5′ substituents

We explore the photophysical, electrochemical, and electroluminescent properties of the ionic transition metal complex [(ppy)2Ir(bpy*)](PF6) where ppyH is 2-phenylpyridine and bpy* is 5,5′-diaryl-2,2′-bipyridine. Single layer devices of the structure ITO/[(ppy)2Ir(bpy*)](PF6)/Au exhibited high stability, with half-lives on the order of 100 h at a bias of −4 V. Long lifetimes are achieved through the bulky nature of the aryl substituents, which serves to limit chromophore–chromophore self-quenching, and 5,5′ positioning of these bulky groups is clearly advantageous for device performance.

Blue light emitting electrochemical cells incorporating triazole-based luminophores

We report the electrochemical, photoluminescence, and electroluminescence properties of four fluorinated cationic iridium complexes bearing pyridyltriazole ancillary ligands. All the complexes display unstructured emission in the true blue region at 298 K with photoluminescent λem ranging from 452 to 487 nm in acetonitrile solution, in powder and in PMMA doped thin films. The nature of the emission is a mixed metal-to-ligand/ligand-to-ligand charge transfer state. Photoluminescence (PL) quantum efficiencies both in solution and in the solid state were low while excited state decay kinetics were found to be multiexponential. Each complex undergoes quasi-reversible oxidation and irreversible reduction with large HOMO–LUMO gaps. A detailed computational investigation corroborates the spectroscopic assignments. Additionally, light-emitting electrochemical cells (LEECs) were fabricated for each of the four complexes. The electroluminescence (EL) spectra of all complexes were red-shifted relative to the PL spectra. The LEEC containing 2a is the bluest emitter (λmax = 487 nm) of the family of complexes.

A rare case of dual emission in a neutral heteroleptic iridium(III) complex

Herein we describe the synthesis and characterization of a neutral heteroleptic iridium complex bearing an unusual 2-pyridyl-6-methylthiazine dioxide ligand (pythdo). X-ray crystallographic analysis reveals that in the complex, the pythdo ligand is twisted and puckered, resulting in very low photoluminescent quantum efficiency. The emission profile is structured. Excited state lifetime measurements along with oxygen quenching studies point to a rare case of dual emission from different excited states whereby the high energy bands possess significant ligand-centered ((3)LC) character while the lower energy bands are predominantly characterized as a mixture of charge transfer ((3)CT) states. A detailed computational analysis corroborates the unusual photophysical behavior.

Correlating electronic structures to electrochemiluminescence of cationic Ir complexes

Electrochemiluminescence (ECL) of heteroleptic cationic iridium complexes is correlated to their structures in order to get insight into tuning their emission wavelength and intensity. While the installation of fluorine and tert-butyl substituents on the ligands increases the electrochemical gap and promotes blue shifts in ECL emission, it reduces ECL efficiencies.

Fraternal twin iridium hemicage chelates

The synthesis and complete photophysical characterization of rigidified neutral hemicage iridium complexes are presented. The hemicage ligands were obtained via a modular synthesis, which will facilitate the expansion of future hemicage syntheses. Slight variations in structure between the two iridium hemicage podates reveal subtle differences in photophysical behavior, which will aid in the design of functional materials. A parallel computational investigation corroborates the experimental findings. The insight gleaned from this study will have an impact for the design of iridium-based luminophores for OLED-type applications.