Red Electrophosphorescence from Oxadiazoles-Functionalized Iridium Complexes in Polymer Light-Emitting Devices

A type of oxadiazole-functionalized iridium complex is newly employed as red phosphor emitter in polymer light-emitting devices (PLEDs) using a blend of poly (9,9-dioctylfluorene)(PFO) and 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole (PBD) as a host matrix. The devices show bright red electrophosphorescence with dominant peaks at about 593nm and shoulders at about 642nm. The highest luminance efficiency of 3.3cd/A at 9.3V and maximum luminance of 2912cd/m² at 14.0V are achieved in the devices. At current density of 100mA/cm², the devices still exhibit luminance efficiency of 2.2cd/A and luminance of 2300cd/m². This indicates that the oxadiazole-functionalized iridium complexes have improved optoelectronic properties in the devices at high current density.