Blue phosphorescent organic light-emitting device with double emitting layer

In this paper, we demonstrated a blue phosphorescent organic light-emitting device (OLED) with a higher current-efficiency and a lower driving-voltage using conventional iridium(III)bis[4,6-(di-fluorophenyl)-pyridinato-N,C2′] picolinate (FIrpic) doped in the double emitting layer (DEML), which consists of a hole- and an electron-transporting material, N,N′-dicarbazolyl-3,5-benzene (mCP) and 2,2′-bis[5-phenyl-2-(1,3,4)oxadazolyl]biphenyl (OXD), respectively. Compared to OLEDs with only single mCP- and OXD-EML, current-efficiency of the optimized DEML-OLED increases by 30.82% and 141.37%, combining with a voltage reduction of 0.34 and 0.59 V at 50 mA/cm2, which comes from the better charge balance in DEML.