The effect of the embedded o-carborane ligand on the photophysical properties of a cyclometalated Pt(II) complex: a theoretical investigation
In recent years, cyclometalated Pt(II) complexes with a terdentate ligand have been used as prospective blue phosphorescent materials. For improving these materials further, the introduction of o-carborane is treated as an excellent strategy to promote the luminescence efficiency. A series of new materials show over 82% phosphorescence quantum yield and good stability, but they are still not fully elucidated. In this work, several different stable o-carborane cages are introduced into the traditional C,N,C-cyclometalated Pt(II) complexes in order to explore their influence completely in contrast to the original phenyl ligand from the view of theoretical investigation. Comprehensive analyses of the geometric structure, molecular orbital and configuration information, spin–orbit coupling elements, vibrational modes, etc. have been carried out. More importantly, our theoretical model highlights that the embedded o-carborane ligands will have an impact on the photophysical properties and quantum efficiency of these Pt(II) complexes significantly, which can provide a valuable guideline for designing and regulating several aspects of highly efficient blue phosphorescent materials.