Electrophosphorescence from a Conjugated Copolymer Doped with an Iridium Complex: High Brightness and Improved Operational Stability

High efficiency electrophosphorescent light‐emitting diodes (LEDs), with an emission peak at 600 nm, a luminance of 2200 cd m–2, and good operational stability were fabricated from a conjugated copolymer doped with an iridium complex. The devices exhibited an external quantum efficiency of 1.5 % and a luminous efficiency of 3 cd A–1. These results demonstrate that electrophosphorescent devices with high brightness and operational stability can be produced in the form of polymer LEDs fabricated by processing the active materials from solution.