Improved Blue-Green Electrophosphorescence from a Tuning Iridium Complex with Benzyl Group in Polymer Light-Emitting Devices

Electroluminescence performances from a tuning biscyclometlated iridium complex with benzyl group are demonstrated in double-layered polymer light-emitting devices (PLEDs) using a blend of poly(9,9-dioctylfluorene) and 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole as a host matrix. Blue-green electrophosphorescent emission with a peak at 521nm and a shoulder at 492nm was observed. The highest luminance efficiency of 4.8cd/A at current density of 0.56mA/cm² and a maximum luminance of 1944cd/m² at 217.6mA/cm² were achieved in the devices at the dopant concentration of 8%. The luminous performance of the devices becomes better with increasing dopant concentrations from 1% → 8%. This implies that the concentration quenching of this iridium complex with benzyl group can be efficiently inhibited
in the devices.