Solution-processed OLEDs based on phosphorescent PtAu2 complexes with phenothiazine-functionalized acetylides

Abstract

Two triphosphine-participated PtAu₂ heterotrinuclear complexes with phenothiazine functionalized acetylides were prepared. The crystal structural determination indicates that because of a short Pt–Au distance of 2.9549(4) Å, the PtAu₂ heterotrinuclear array supported by double triphosphine ligands exhibits substantial Pt–Au intermetallic contact. The PtAu₂ complexes show moderate phosphorescent emission in fluid solution and the powder state, but intense orange and yellow phosphorescence in doped poly(methyl methacrylate) films with quantum yields of 73.7% and 48.9%, respectively. The phosphorescence arises from an admixture of ³[π(phenothiazine–acetylide) → π*(triphosphine)] ³LLCT and ³[π(phenothiazine–acetylide) → p/s(PtAu₂)] ³LMCT triplet excited states. Utilizing blended host materials composed of both hole-transport TAPC and electron-transport OXD-7 doping with 8% phosphorescent PtAu₂ complex as emitting layer, solution-processed organic light-emitting diodes (OLEDs) gave orange electroluminescence with the highest current efficiency of 35.4 cd A⁻¹ and external quantum efficiency of 18.7%.