Samsung Advanced Institute of Technology

This research elucidates the effects of structural modulations on electroluminescent Au(I) complexes, shedding light on factors governing radiative and nonradiative processes. A series of Au(I) complexes, fortified with ortho-substituents in carbene and amido ligands, have been subjected to rigorous structural, photophysical, and quantum chemical investigations, which unveils distinct structural and electronic effects exterted by the ligands. Our investigations reveal that nonradiative processes are governed primarily by the energy-gap law, but are only weakly associated with the stric crowding at the Au(I) center. Radiative processes are observed to have a weak correlation with the mutual interactions of the molecular orbitals of carbene and amido ligands. Rather, it is discovered that a decrease in the charge in the Au 5d orbital in the excited state accelerates radiative processes. Effectiveness of these findings are substantiated through the superior operational stability and the larger external quantum efficiency of electroluminescence devices employing our Au(I) complex, in comparison to those based on the archetypical Au(I) complex and the organic thermally activated delayed fluorescent molecule. These compelling revelations underscore the untapped potential of Au(I) complexes in the advancement of electroluminescence technology and advocate for continued investigation into the intriguing domain of ligand structural control.