Lantern-like Cu8 cluster for high-efficiency electrically driven light-emitting diodes

A novel lantern-like Cu(I) cluster [Cu₈(2-pyCC)₆(<i>N</i>-triphos^Ph)₂](PF₆)₂ (Cu8) was synthesized with high yield <i>via</i> ligand engineering, featuring mixed multidentate ligands of tris(diphenylphosphinomethyl)amine (<i>N</i>-triphos^Ph) and 2-pyridylethynyl (2-pyCCH). Its structure was thoroughly characterized using spectroscopic methods and X-ray crystallography. These techniques indicate that strategically introducing two kinds of multidentate ligands helps to enhance the overall stability of the lantern-like Cu8. Cu8 exhibits intense red photoluminescence (PL) at room temperature in the crystalline state, with a high PLQY of up to 31.4%. Significantly, Cu8 shows remarkable aggregation-induced emission enhancement (AIEE) in DMSO/H₂O solution, as well as distinct temperature-responsive luminescence. Based on its excellent photophysical and chemical properties, Cu8 was employed as a light-emitting dopant in electrically driven organic light-emitting diodes (OLEDs) with an external quantum efficiency (EQE) of 14.3% at 500 cd m^-2.