Enhancement of the luminance efficiency in blue organic light-emitting devices fabricated utilizing a hybrid phosphorescence and fluorescence emitting layer

Abstract

Blue organic light-emitting devices (OLEDs) fabricated utilizing a hybrid emitting layer (EML) consisting of a bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)iridiumIII (FIrpic)-doped 1,3-bis(carbazol-9-yl)benzene (mCP) layer, a 2-methyl-9,10-bis(naphthalene-2-yl)anthracene (MADN)-doped mCP layer, and a 2,9-dimethyl-4,7-diphenyl-1,10-phenanthorlene (BCP)-doped MADN layer were fabricated to investigate their luminance efficiency enhancement. The FIrpic-doped mCP layer, the MADN-doped mCP layer, and the BCP-doped MADN layer in the blue OLEDs acted as a phosphorescence EML, a fluorescence EML, and an exciton blocking layer, respectively. The maximum luminance efficiency and the maximum brightness of the OLEDa were as large as 8.36 cd/A and 16,000 cd/m 2, respectively, which were larger than those of conventional phosphorescence blue OLEDs with a FIrpic-doped mCP EML.