Nido‐Ortho‐Carborane‐Functionalized Salt‐Type Tetradentate Pt(II) Complexes and Their Application as Blue Phosphors in Efficient Organic Light‐Emitting Diodes

This study presents the synthesis of two novel salt‐type tetradentate Pt(II) complexes, nPt1C and nPt2C , functionalized with nido‐ortho‐carborane. Spectroscopic and theoretical analyses reveal that nido‐carborane introduces an anionic character, modulating energy levels and enabling efficient triplet‐based charge transfer. Its steric bulk also minimizes intermolecular interactions, ensuring narrow‐band blue emission and strong photophysical stability. Both complexes exhibit high photoluminescence quantum yields (>82%) and short decay lifetimes (<1.1 µs), confirming efficient radiative pathways. Cyclic voltammetry indicates excellent electrochemical stability. OLEDs doped with nPt1C and nPt2C achieve high external quantum efficiencies (up to 16.2%) with sharp blue electroluminescence (CIEy < 0.16, FWHM = 22 nm). The emission spectra remain stable under operating conditions, confirming robust radiative mechanisms. The presence of countercations and nido ‐carborane enhances electronic and steric control without impairing performance. Comparative analyses highlight their competitive efficiency among tetradentate Pt(II) complexes. These findings demonstrate the potential of nido‐carborane for fine‐tuning electronic structures, advancing next‐generation high‐efficiency blue OLED materials.