Highly Luminescent Pincer Gold(III) Aryl Emitters: Thermally Activated Delayed Fluorescence and Solution-Processed OLEDs

Abstract

Herein are described the synthesis, photophysical properties and applications of a series of luminescent cyclometalated Au^III complexes having an auxiliary aryl ligand. These complexes show photoluminescence with emission quantum yields of up to 0.79 in solution and 0.84 in thin films (4 wt % in PMMA) at room temperature, both of which are the highest reported values among Au^III complexes. Thermally activated delayed fluorescence (TADF) is the emission origin for some of these complexes. Solution-processed OLEDs made with these complexes showed sky-blue to green electroluminescence with external quantum efficiencies (EQEs) of up to 23.8 %, current efficiencies of up to 70.4 cd A^-1 , and roll-off of down to 1 %, highlighting the bright prospect of Au^III -TADF emitters in OLEDs.

Keywords: gold; ligand-to-ligand charge transfer; organic light-emitting devices (OLEDs); pincer ligands; thermally activated delayed fluorescence (TADF).