Molecular design of hole-transporting material for efficient and stable green phosphorescent organic light-emitting diodes

We examined the hole-transporting-material (HTM)-dependent device characteristics of green phosphorescent organic light-emitting diodes (PHOLEDs) using an electron-transporting host. The emission efficiency of the PHOLEDs was proportional to the optical band gap and the triplet energy of the HTMs. On the other hand, the operational stability of the PHOLEDs was not proportional to the emission efficiency. By analyzing the device characteristics in relation to the molecular structure of HTMs, amine derivative with dibenzothiophene was found to be effective HTMs suitable for highly efficient and stable green PHOLEDs.