Carbazole-functionalized europium complex and its high-efficiency organic electroluminescent properties

A complex tris(dibenzoylmethanato){1-ethyl-2-(N-ethyl-carbazole-yl-4) imidazo[4,5-f]1,10-phenanthroline} europium(III) [Eu(DBM)(3)phencarz] functionalized by a hole-transport group carbazole was synthesized. Devices using this complex as emitter showed greatly enhanced performance benefited from the increased hole-transport properties and efficient energy transfer from carbazole to the central ions. A 58-nm-single-layer device gave a brightness of 20 cd/m(2) at 15 V. The highest power efficiency of 2.7 lm/W at 5 V and 0.5 cd/m(2) and the luminance exceeding 2000 cd/m(2) at 20 V was obtained from a device with the configuration of ITO/TPD(20 nm)/Eu(DBM)(3)phencarz(40 nm)/BCP(20 nm)/AlQ(40 nm)/Mg0.9Ag0.1(200 nm)/Ag(80 nm). (C) 2003 American Institute of Physics.