Homoleptic Iridium(III) Complexes based on Fused Dibenzothiophene and N-Heterocyclic Carbene (NHC) Moiety for Efficient Blue Phosphorescent OLEDs
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초록
내용
The NHC–Ir complexes f-IrSiPr, m-IrSiPr, and m-IrSMe, in which a dibenzothiophene (DBT) moiety is used to increase the emission efficiency for deep-blue phosphorescence, were synthesized and compared with the dibenzofuran (DBF)-based Ir complexes f-IrOMe and m-IrOMe. The DBF moiety has a stronger electronegativity than DBT, resulting in a larger T1–S0 energy gap and a shorter emission wavelength than those of the DBT complexes. The replacement of the oxygen atom in the DBF unit with sulfur does not greatly alter the emission efficiency in either solution or film while achieving the same high-end deep-blue phosphorescence with unprecedented CIE coordinates of [0.14, 0.19] for m-IrSMe (EQEmax; 17.1%) and [0.14, 0.14] for m-IrOMe (EQEmax; 18.2%).