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A novel Er(III) β-diketonate complex, tris(dibenzoylmethanate)mono(triphenylphosphine oxide) erbium(III) or [Er(dbm)3(tppo)] was synthesised with dbm as a main sensitizer and tppo as a synergic ligand. The single crystal X-ray analysis reveals that the crystal structure of the complex is a triclinic centrosymmetric where Er(III) ion is coordinated to seven oxygen atoms; one O-atom from one tppo and six O-atoms from three dbm ligands. Shape-measure criterion measurements show that the complex possesses a distorted monocapped octahedron geometry, which facilitates the radiative transitions that is an indicative of efficient energy transfer from coordinated ligands to Er ion. The crystal structure is stabilised by the π–π stacking and CH/π interactions which lead to its high photo- and thermal stabilities. The complex was doped into a polymer matrix and the resulted material shows an enhanced luminescence intensity as well as full width at half maximum (fwhm) which allow its possible use for optical-amplification applications. Finally, a single layered organic diode was fabricated to determine charge carrier mobility (μ0) inside the complex. For this purpose, the Mott–Gurney model was used which gave sizable μ0 of 3.39 × 10−9 cm2/Vs (at

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.