Excited State Modulation in Carbene‐Metal‐Amides to Design Fast and Bright Blue Delayed Fluorescence

Abstract The gold‐based carbene‐metal‐amide (CMA) complexes with a 1,2,3,9‐tetrahydro‐4 H ‐carbazol‐4‐one amide ( L ) have been prepared in good yields and photophysically characterized. The carbonyl‐substituted amide donor ligand resulted in a 0.2 eV increase of the locally excited triplet state ( 3 LE), preventing parasitic phosphorescence and enabling a small singlet‐triplet energy gap (ΔE ST ) down to 30 meV. The series of deep‐blue/green CMA complexes emits light via a thermally active delayed fluorescence mechanism with high radiative rates ( k r ) up to 2.4 × 10 6 s −1 . The complex CAAC AuL represents the first known example of a CMA complex with a keto substituted amide ligand to exhibit deep‐blue TADF (λ max = 450 nm, k r = 6.7 ×10 5 s −1 ) photoluminescence.