Efficient red-emitting electrophosphorescent polymers

We report the synthesis and characterization of a series of electrophosphorescent polymers with a polyfluorene backbone, containing a red-emitting iridium complex and carrier-transporting units as the substitutes of the C-9 position of fluorene. Different specimens and contents of the hole-transporting moieties were found to influence the electroluminescent properties of the polymers. Incorporation of a hole-transporting/electron-blocking interfacial layer and utilization of an efficient electron injection cathode led to the saturated red-emitting electrophosphorescent polymer devices with the peak luminance efficiency and power conversion efficiency of 9.3 cd A(-1) and 10.5 lm W-1, respectively. The efficiencies were 8 cd A(-1)/8 lm W-1 and 5.9 cd A(-1)/4.6 lm W-1, respectively, at 100 and 1000 cd m(-2).