Bright and monochromic red light-emitting electroluminescence devices based on a new multifunctional europium ternary complex

A novel europium(III) complex, tris(dibenzoylmethanato)(2-4ʹ-triphenylamino)imidazo[4,5-f]1,10-phenanthroline)euro-pium(III), Eu(DBM)3(TPIP), is synthesized. The light-emitting center, hole-transporting triphenylamine and electron-transporting phenanthroline fragments are integrated into one molecule. A single-layer device of ITO/Eu(DBM)3(TPIP)(60 nm)/Mg0.9Ag0.1/Ag exhibits EuIII-based pure red emission with a maximum brightness of 19 cd m–2 at 13.5 V and 280 mA cm–2, and an onset driving voltage of 8 V. A four-layer device of ITO/TPD (20 nm)/Eu (DBM)3(TPIP) (40 nm)/BCP (20 nm)/AlQ(40 nm)/Mg0.9Ag0.1/Ag gives a maximum EuIII-based pure red emitting luminance of 1305 cd m–2 at 16 V and 255 mA cm–2 with an onset driving voltage of 6 V; the maximum external quantum yield and luminous yield are estimated to be 0.85% and 1.44 lm W–1, respectively, at 7.5 V and 0.25 mA cm–2.