A Novel Efficient Red Emitting Iridium Complex for Polymer Light Emitting Diodes

Photo-physical properties of iridium complexes bis(1-(2',4'-difluorobiphenyl -4-yl)isoquinoline)iridium(III)(5-(4-(bis(4-methoxyphenyl)amino)phenyl) picolinic acid) used as phosphorescent dopant in polymer light-emitting devices with a blend ofpoly(9,9-dioctylfluorene) and 2-tert-butyl-phenyl-5-biphenyl-1,3,4-oxadiazole as a host matrix are investigated. The iridium complex exhibits distinct UV-vis absorption bands around 300–450 nm and intense red photoluminescent emissions peaked at around 618 nm in dichloromethane. The devices display a maximum external quantum efficiency of 4.8% and luminous efficiency of 3.1 cd·A−1 at current density of 3.2 mA·cm−2 with a dominant red emission peak around 620 nm and a shoulder around 660 nm. At 100 mA·cm−2, the devices still display a maximum external quantum efficiency as high as 3.9%