Near-Infrared Photoluminescence and Electroluminescence of Neodymium(III), Erbium(III), and Ytterbium(III) Complexes

Tris(dibenzoylmethanato)(monobathophenanthroline)lanthanide(III) complex [Ln(DBM) 3 bath (Ln: Nd, Er and Yb)] both in solutions and thin films at room temperature showed narrow band photoluminescence (PL) due to the f – f transitions in the near-IR region: 890, 1070 and 1350 nm for Nd(III), 980 and 1540 nm for Er(III), and 985 nm for Yb(III). The PL efficiencies in solution were determined [φ PL =3.3×10 -3 for Nd(III), 7.0×10 -5 for Er(III), and 1.4×10 -2 for Yb(III)]. Organic electroluminescent (EL) devices having the structure of glass substrate/indium-tin oxide/ N , N ′ -diphenyl- N , N ′ -di( m -tolyl)benzidine/Ln(DBM) 3 bath(Ln: Nd, Er and Yb)/bathocuproine/Mg:Ag/Ag were fabricated, giving the EL bands around 900–1600 nm at room temperature. The external near-IR EL efficiencies at low current density were estimated by comparing with that of the Eu(III) device having the same structure. The saturation of near-IR EL intensity observed at the high current density suggested that the near-IR EL should suffer the T–T annihilation.