High efficiency red organic light-emitting devices using tetraphenyldibenzoperiflanthene-doped rubrene as an emitting layer

Red organic light-emitting devices (OLEDs) have been developed employing a novel fluorescent emitting layer, tetraphenyldibenzoperiflanthene-doped rubrene. The devices are characterized by low driving voltage below 4 V at a current density of 20 mA/cm(2) and high color purity with Commission Internationale de l'Eclairage coordinates of (0.66, 0.34). The OLED using the novel emitting layer in combination with the electron-transporting layer consisting of 9,10-bis[4-(6-methylbenzothiazol-2-yl)phenyl]anthracene exhibits a high power efficiency of 5.3 lm/W at a current density of 20 mA/cm(2). The half-luminance lifetime of the red OLED is 223 h at a current density of 80 mA/cm(2) (initial luminance of 3570 cd/m(2)). Both the driving voltage and current efficiency of the device are significantly improved compared to a device using tris(8-quinolinolato)aluminum as an electron-transporting layer. The studies on charge transport for the host materials indicate that the high efficiency is attributed to the improved charge injection and balance in the device. (c) 2006 American Institute of Physics.