2-Mercaptobenzothiazolate complexes of rare earth metals and their electroluminescent properties

Abstract

We have demonstrated the electroluminescent (EL) properties of 2-mercaptobenzothiazolate complexes of rare earth metals [Ln(mbt) 3, Ln = Y, Sm, Eu, Gd, Tb, Dy, Tm] using simple non-doped two-layer organic light emitting diode with the configuration of indium tin oxide/ N, N′-bis(3-methylphenyl)- N, N′-diphenylbenzidine/Ln(mbt) 3/Yb. It was found that 2-mercaptobenzothiazolate complexes have highly efficient intra-energy transfer from the singlet to the triplet state of the ligand, and then to the excited state of the central lanthanide ions. Thus Y(mbt) 3 and Gd(mbt) 3 exhibit the broad ligand-centered emission with maximum near 600 nm and Dy(mbt) 3, Tb(mbt) 3 and Tm(mbt) 3 complexes exhibit pure sharp emission bands from the intra f–f transitions of lanthanide ions Tb 3+: 5D 4 → 7F 6 (492 nm), 5D 4 → 7F 5 (547 nm), 5D 4 → 7F 4 (589 nm), 5D 4 → 7F 3 (624 nm); Dy 3+: 4F 9/2 → 6H 13/2 (575 nm) and Tm 3+: 3H 4– 3H 6 (795 нм).