Improving the quantum yield of luminescence for three-coordinated gold(i) TADF emitters by exploiting inversion symmetry and using perhaloaryl ligands

Abstract

Herein, we report the synthesis of a new family of extremely efficient TADF three-coordinated gold(I) emitters based on the chelating and bridging abilities of the 1,2,4,5-tetrakis(diphenylphosphino)benzene (tpbz) ligand and the neutral gold(I) [AuR] fragments (R = C₆F₅ (1), C₆Cl₂F₃ (2), C₆Cl₅ (3)). Their emission energies appear in the orange range of the spectrum. The quantum yields of the emissions are directly related to the electronegativity of the perhalophenyl groups bonded to the metal center, even when they are not directly involved in the orbitals responsible for the luminescence. DFT and TD-DFT calculations suggest that the symmetry of the solid-state structures facilitates the coupling of the transition dipole moments, which leads to a drastic increase in their quantum yields as the electronic accepting abilities of the perhalophenyl groups decreases.