Synthesis and NIR-optoelectronic properties of a seven-coordinate ytterbium tris β-diketonate complex with C3v geometrical structure

A low symmetry NIR emitting ytterbium (III) β-diketonate ternary complex with composition, [Yb(tta)3(tppo)]·H2O (tta = thenoyltrifluoroacetylacetone and tppo = triphenyl phosphine oxide) was synthesized and fully characterized. Single crystal X-ray analysis and shape measurement calculations indicate that the complex is a seven-coordinate and possesses distorted trigonal prism geometry with coordination polyhedra YbO7 where the Yb(III) ion is surrounded by seven oxygen atoms of three tta and one tppo ligands. It is a highly asymmetric structure enhancing the radiative transitions which is an indicative of efficient energy transfer from coordinated ligands to Yb ion. The complex was doped in a tris(4-carbazoyl-9-ylphenyl)amine (TcTa) matrix and used as an emitting layer to fabricate near-infrared organic light emitting device (NIR-OLED) with the structure: ITO/{N,N′-bis(naphtalen-2-yl)-N,N′-bis(phenyl) benzidine} (25 nm)/[Yb-complex] (10%): TcTa (40 nm)/BCP (15 nm)/Alq3 (10 nm)/LiF (0.5 nm)/Al (120 nm). The complex based NIR-OLED showed good EL efficiency with maximum irradiance of 19.29 μW/cm2 and current density of 27.3 mA/cm2 at 15 V. In view of electrical characteristics, the charge carrier mobility, μ0, of the complex was determined by using Mott–Gurney model which gave a sizable value of 4.50 × 10−8 cm2/Vs.

A seven-coordinate NIR emitting complex, [Yb(tta)3(tppo)]·H2O was synthesized. X-ray single crystal analysis indicates distorted trigonal prism geometry of complex, a highly asymmetry structure suggesting efficient energy transfer process. The complex was used to fabricate NIR-OLED. Mott–Gurney model was used to determine carrier mobility of complex.Figure optionsDownload as PowerPoint slide