Synthesis and Properties of 9,9′-Diaryl-4,5-diazafluorenes. A New Type of Electron-Transporting and Hole-Blocking Material in EL Device

The title compounds were prepared and investigated for electron-transporting and hole-blocking materials in organic electroluminescent (EL) devices. EL efficiencies of the phosphorescent devices indicated high performance of hole-blocking ability in the compounds. A maximum external efficiency of 18% was achieved and a maximum power luminous efficiency was over 45 Lm W−1.