Tetradentate Gold(III) Complexes as Thermally Activated Delayed Fluorescence (TADF) Emitters: Microwave-Assisted Synthesis and High-Performance OLEDs with Long Operational Lifetime

Structurally robust tetradentate gold(III)-emitters have potent material applications but are rare and unprecedented for those displaying thermally activated delayed fluorescence (TADF). Herein, a novel synthetic route leading to the preparation of highly emissive, charge-neutral tetradentate [C<^>C<^>N<^>C] gold(III) complexes with 5-5-6-membered chelate rings has been developed through microwave-assisted C-H bond activation. These complexes show high thermal stability and with emission origin ((IL)-I-3, (ILCT)-I-3, and TADF) tuned by varying the substituents of the C<^>C<^>N<^>C ligand. With phenoxazine/diphenylamine substituent, we prepared the first tetradentate gold(III) complexes that are TADF emitters with emission quantum yields of up to 94 % and emission lifetimes of down to 0.62 mu s in deoxygenated toluene. These tetradentate Au-III TADF emitters showed good performance in vacuum-deposited OLEDs with maximum EQEs of up to 25 % and LT95 of up to 5280 h at 100 cd m(-2).