Metallophosphors of iridium(III) containing borylated oligothiophenes with electroluminescence down to the near-infrared region

The synthesis, structural, electrochemical and photophysical studies of a series of cyclometalated iridium(III) complexes with functionalized borylated oligothiophene ligands are reported. The effect of oligothiophene chain length on the photophysical properties of these metal complexes was examined in detail and their excited state properties can be controlled by increasing the number of thienyl rings in the cyclometalating ligand, thus allowing the emission to be tuned from red to near-infrared. All of the iridium(III) complexes were utilized in the fabrication of phosphorescent organic light-emitting diodes and their device performances were investigated. These electrophosphors emit in the red to near-infrared regions. The present work enables the rational design of new borylated iridium phosphors by synthetically tailoring the structure of oligothiophene-based pyridine ring that can permit color tuning toward near-infrared phosphorescence.