Highly efficient sharp red electroluminescence from europium complex-doped poly(9,9-dioctylfluorene) devices

Using a europium complex containing bromine groups as a guest dopant and a blend of poly(9,9-dioctylfluorene) and 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole as a host matrix, the polymer light-emitting devices exhibited bright red electroluminescent emissions at 612 nm with a full width at half maximum of 19 nm. The different spectral characteristics of photoluminescence and electroluminescence were analyzed. Highly efficient emission was observed in the devices with a maximum external quantum efficiency of 1.4% at 1.5 mA/cm2 and a peak luminance of 278 cd/m2 at 50.0 mA/cm2.