White polymer light-emitting devices with a peak forward-viewing power efficiency close to 40 lm W-1, corresponding to an external quantum efficiency of 28.8% and a luminous efficiency of 60 cd A(-1), are demonstrated. The devices are based on two newly synthesized yellow-emitting iridium complexes functionalized with the sterically hindered diarylfluorene chromophores and are fabricated by a simple solution-processing method.