Green phosphorescent organic light-emitting devices based on different electron transport layers combining with fluorescent sub-monolayer

We report a small molecule host of 4,4(-N,N)-dicarbazole-biphenyl (CBP) doped with 8% tris(2-phenylpyridine) iridium (Irppy3) for use in efficient green phosphorescent organic light-emitting devices (PHOLEDs) combined with different electron transport layers of Alq and BAlq. The PHOLEDs exhibit maximum current efficiency and power efficiency of 19.8 cd/A and 6.21 lm/W, respectively. The high performance of such PHOLEDs is attributed to the better electron mobile ability of BAlq and sub-monolayer quinacridone (QAD) as carrier trapping layer and equal charge carrier mobilities of hole and electron to form the broad carrier recombination zone in the emitting layer, which can reduce the triplet-triplet annihilation and improve the efficiency of the device. #$TABThis work has been supported by the Major Project of Science and Technology Office of Fujian Province of China (No.2014H0042), the Natural Science Foundation of Fujian Province of China (No.2015J01664), the Project of Science and Technology Research of Quanzhou in Fujian Province of China (Nos.2013Z125 and 2014Z137), and the 2016 Annual National or Ministries Preparatory Research Foundation Project in Quanzhou Normal University (No.2016YYKJ21). E-mail:yanghuishan1697@163.com