Highly efficient bilayer green phosphorescent organic light emitting devices

We present a highly efficient green phosphorescent device comprising only of two organic layers. A host material bis[2-(2-hydroxyphenyl)-pyridine]beryllium having a good electron transporting and energy transfer characteristics, and a wide band gap hole transport material N,N-'-di(4-(N,N-'-diphenyl-amino)phenyl)-N,N-'-diphenylbenzidine lead to the fabrication of a simplified high efficiency device. The driving voltage value of 3.3 V to reach a luminance of 1000 cd/m(2) is reported. The maximum current- and power-efficiency values of 38.30 cd/A and 46.60 lm/W are demonstrated in this device. Results reveal a practical way to fabricate highly efficient truly bilayer organic devices for trouble-free manufacturing processes. (c) 2008 American Institute of Physics.