Pure Near-Infrared Iridium Complexes with Rigid Oxygen-Bridged Boron Units and Solution-Processed OLED Application

Near-infrared (NIR) phosphorescent materials exhibiting emission peaks beyond 700 nm hold substantial importance for advancements in optoelectronics and biomedicine. In this study, two novel near-infrared iridium complexes (Ir(Bpa) 2 dpm and Ir(Bqz) 2 dpm) were successfully constructed by incorporating rigid oxygen-bridged boron moieties in combination with either phenanthridine or quinazoline units. Notably, both complexes display pure near-infrared emissions exceeding 750 nm, with their respective emission peaks positioned at 756 and 787 nm, thus demonstrating high near-infrared purity (>98%). Given its superior optical characteristics and good solubility, Ir(Bpa) 2 dpm was selected as the emissive layer material for a solution-processed organic light-emitting diode (OLED) device. The fabricated device demonstrated a good maximum external quantum efficiency (EQE) of 1.2%, along with an emission peak centered at 760 nm. This research offers a crucial approach for designing pure near-infrared (NIR) phosphorescent iridium complexes and their utilization in optoelectronic devices.