B-embedded narrowband pure near-infrared (NIR) phosphorescent iridium(III) complexes and solution-processed OLED application

Pure near-infrared (NIR) phosphorescent materials with emission peak larger than 700 nm are of great significance for the development of optoelectronics and biomedicine. We have designed and synthesized two new B-embedded pure near-infrared (NIR)-emitting iridium complexes (Ir(Bpiq)2acac and Ir(Bpiq)2dpm) with peaks greater than 720 nm. More importantly, they exhibit very narrow phosphorescent emission with full width at half maximum (FWHM) of only about 50 nm (0.12 eV), resulting in a high NIR content (> 90%) in their spectrum. In view of better optical property and solubility, the complex Ir(Bpiq)2dpm was used as the emitting layer of a solution-processed OLED device, and achieved good maximum external quantum efficiency (EQE) (2.8%) peaking at 728 nm. This research provides an important strategy for the design of narrowband NIR-emitting phosphorescent iridium complexes and their optoelectronic applications.