Thiazoline Carbene−Au(I)−Amide complexes exhibiting dimer electroluminescence

Abstract

Two-coordinate coinage metal (Cu, Ag and Au) complexes with linear carbene–metal–amide (CMA) structure have recently emerged as promising thermally activated delayed fluorescence (TADF) emitters for OLED application. Herein we investigate a series of eight new Au(I) CMA complexes, which incorporate derivatives of 1,3-thiazoline as N-heterocyclic carbene (NHC) ligands. The complexes exhibit blue to green luminescence in thin films. A limitation of the torsional motions around the metal-ligand axis in a combination with the heavy gold atom effect enables highly efficient TADF with photoluminescence quantum yield (PLQY) of up to 0.99 and radiative rates nearing 1·106 s−1. A formation of emissive dimers of complex molecules was observed in vacuum processed OLEDs. Achieved dual electroluminescence from the redshifted (by 120 nm) dimeric species in a combination with co-occurring monomer emission opens potential application prospects in construction of single-emitter white OLEDs.