High Efficiency and\nNarrow Emissions in Deep-Blue\nPt(II) Emitters in Organic\nLight-Emitting Diodes via Anchor-Shaped Substituent Design

In this study, a tetradentate Pt(II) complex designed\nto have <i>N</i>-heterocyclic carbene ligands modified with\nan anchor-shaped\n2,6-diisopropylphenyl (dip) group is described to enhance molecular\nrigidity for narrow emission and high efficiency. The tetradentate\nligand with the dip group significantly hinders steric interactions\nand restricts π-conjugation from benzocarbene, leading to shallow\nlowest unoccupied molecular orbital levels and a consequent reduction\nin the triplet metal-to-ligand charge transfer character. These structural\nmodifications result in narrow emission spectra and enhanced efficiency\nfor blue organic light-emitting diodes (OLEDs) over wide doping concentration\nranges. These blue OLEDs exhibit deep-blue emissions at 455 nm with\ncolor coordinates of (0.139, 0.090), a full width at half-maximum\nof 17 nm, and a high maximum external quantum efficiency of 24.1%\nat a doping concentration of 10 wt %. In addition, the OLED performance\nwas stably maintained at a doping concentration of 20 wt %. Overall,\nthe anchor-shaped dip group significantly enhances the rigidity of\nthe ligand in the tetradentate Pt(II) complex, effectively reducing\nintermolecular interactions and allowing the complex to function as\na highly efficient and pure deep-blue emitter.