Highly Phosphorescent Dimers of PtAu₂ Complexes and the Use in Solution-Processed OLEDs

Two asymmetric PtAu2 complexes having HCCC6H4CCH (1,4-diethynylbenzene) or HCCCarbCCH (2,7-diethynyl-9-(2,3,5,6-tetrafluorophenyl)-9H-carbazole) and the corresponding bis­(acetylide)-linked Pt2Au4 complexes are prepared and characterized. The structures of PtAu2 complexes 1 and 3 together with Pt2Au4 complex 2 are determined by X-ray crystallography. Relative to PtAu2 complexes, bis­(acetylide)-linked Pt2Au4 complexes not only display a distinct red shift of the emission but also provide a much higher phosphorescent efficiency. Utilizing highly emissive Pt2Au4 complexes as phosphorescent dopants, high-efficiency solution-processed OLEDs are obtained with peak current efficiency of 75.9 cd A–1 and external quantum efficiency of 19.0% at luminance of 336 cd m–2 and voltage of 5.2 V. When two PtAu2 moieties are linked by a bis­(acetylide) ligand, the corresponding Pt2Au4 complexes show a much improved electroluminescent performance compared with that of asymmetric PtAu2 complexes.