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

Abstract

A novel europium(III) complex, tris(dibenzoylmethanato)(2-4′-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)/Mg_0.9Ag_0.1/Ag exhibits Eu^III-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)/Mg_0.9Ag_0.1/Ag gives a maximum Eu^III-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.