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

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 Tb3+: 5D4 → 7F6 (492 nm), 5D4 → 7F5 (547 nm), 5D4 → 7F4 (589 nm), 5D4 → 7F3 (624 nm); Dy3+: 4F9/2 → 6H13/2 (575 nm) and Tm3+: 3H4–3H6 (795 нм).