Phosphorescent organic light-emitting device with an ambipolar oxadiazole host

In this latter, the authors demonstrated a phosphorescent organic light-emitting device OLED with a lower driving voltage and a longer operation lifetime based on 2,2 -bis 5-phenyl-21,3,4 oxadazolyl biphenyl, an oxadiazole OXD derivative, as the host of the emitting layer doped with a common green-emitting phosphorescent dopant, fac-tris 2-phenylpyridine iridium Ir ppy 3 . Rather than an electron transporting materials, the OXD exhibits an ambipolar transport characteristic with suitable Ir ppy 3 concentrations due to its low highest occupied molecular orbital value 5.9 eV and the hole-transporting characteristics of Ir ppy 3. It results in a 2.4 V voltage reduction and a 2.6 times lifetime elongation of the OXD-based device, as compared to the conventional phosphorescent OLED. © 2007 American Institute of Physics. DOI: 10.1063/1.2747663