Vacuum-vaporized films of fluorescent europium complexes and their device applications

A series of ternary europium(III) complexes have been tested for vacuum-deposited thin films. Using infrared and fluorescent spectroscopy, we have characterized the complexes tris(alpha-thenoyltrifluoroacetonato)mono(1,10-phenanthroline)europium(III) and tris(alpha-thenoyltrifluoroacetonato)mono(4,7-diphenyl-1,10-phenanthroline)europium(III), Eu(TTA)(3)phen and Eu-(TTA)(3)4.7phen, respectively, to form uniform films with strong fluorescence comparable to their pellets. The rectifying effects have been observed in the devices of both (-)Al/Eu(TTA)(3)4.7phen/ITO(+) and (-)Al/Eu(TTA)(3) phen/ITO(+). At an onset voltage of ca. 8 V, the two-layer device (+)ITO/Eu (TTA)(3)4.7phen/Alq(3)/Al(-) (Alq(3) = tris(8-hydroxyquinolinato)-aluminum) emited blue-shifted light of wavelength 575 nm, compared to the Alq(3)-based single-layer device (+)ITO/Alq(3)/Al(-).