Highly efficient and bright electroluminescent Ru(bpy)3(ClO4)2/Alq3 device -: art. no. 061110

Electroluminescent devices of indium tin oxide (ITO)/Alq(3)(212 nm)/Ru(bpy)(3)(ClO4)(2)(100 nm)/Ga:In were fabricated and showed high external quantum and power efficiencies, of 6.4% and 5.3%, respectively, at an optical output power of 0.4 mW/cm(2) under a bias of 2.3 V. At a higher bias voltage (> 2.7 V), the output power was well above 10 mW/cm(2), but with a lower efficiency. Light emission occurred at the interface between Alq(3) and Ru(bpy)(3)(ClO4)(2), whose relative energies of both excited and ground states were offset, ideal for confining both charge carriers and minimizing the quenching of the Ru(bpy)(3)(2+) excited state. By comparison, in a single layer device without Alq(3), the emission zone was located at the ITO interface where excited states were quenched and electron injection from the reduced molecules to the ITO contact produced a unipolar current and thus lower efficiency. (c) 2005 American Institute of Physics.