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

초록

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 <mu>s), 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.

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