Abstract
Organic light-emitting diodes (OLEDs) have attracted a great attention due to their application in high-resolution, full-color, flat-panel displays and lighting sources. [1-6] The search for highly efficient three primary color (red, green, and blue) emitters is an important subject for OLEDs. [7] Phosphorescence devices have continued to attract intense interest because their intrinsic efficiencies could be four times as high as the fluorescence ones. [8] . © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.