Highly Luminescent Europium(III) Complexes in Solution and PMMA-Doped Films for Bright Red Electroluminescent Devices.

This paper reports the synthesis, structure, photophysical, and optoelectronic properties of five eight-coordinate Europium(III) ternary complexes, namely, [Eu(hth) ₃ (L) ₂ ], bearing 4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl)-1,3-hexanedione (hth) as a sensitizer and L = H ₂ O ( 1 ), dpso (diphenyl sulphoxide, 2 ), dpsoCH ₃ (4,4'-dimethyl diphenyl sulfoxide, 3 ), dpsoCl (bis(4-chlorophenyl)sulphoxide, 4 ), and tppo (triphenylphosphine oxide, 5 ) as co-ligands. The NMR and the crystal structure analysis confirmed the eight-coordinate structures of the complexes in solution and in a solid state. Upon UV-excitation on the absorption band of the β-diketonate ligand hth, all complexes showed the characteristic bright red luminescence of the Europium ion. The tppo derivative ( 5 ) displayed the highest quantum yield (up to 66%). As a result, an organic light-emitting device, OLED, was fabricated with a multi-layered structure-ITO/MoO ₃ /mCP/SF3PO:[complex 5 ] (10%)/TPBi:[complex 5 ] (10%)/TmPyPB/LiF/Al-using complex 5 as the emitting component.