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

Abstract

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(α-thenoyltrifluoroacetonato)mono(1,10-phenanthroline)europium(III) and tris(α-thenoyltrifluoroacetonato)mono(4,7-diphenyl-1,10-phenanthroline)europium(III), Eu(TTA) 3phen and Eu(TTA) 34.7phen, 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) 34.7phen/ITO(+) and (−)Al/Eu(TTA) 3 phen/ITO(+). At an onset voltage of ca. 8 V, the two-layer device(+)ITO/Eu (TTA) 34.7phen/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(−).