Highly efficient yellow organic light emitting diode based on a layer-cross faded emission layer allowing easy color tuning

摘要

An easy way to adjust the color of yellow organic light emitting diodes (OLED) is realized by basing the emission layer on a cross-fading zone of two unipolar-conducting host materials doping parts of it either with a red or green phosphorescent emitter at varying thickness ratios. At color coordinates of 0.47/0.50, a current efficacy of 42.2 cd/A (16.2% external quantum efficiency) and a power efficacy of 32.9 lm/W (1000 cd/m~2) are measured without light extraction enhancement. Mixed-host emission layer OLED without cross-fading are processed for comparison. Exciton distributions are studied. The concept is suggested to be useful for white OLED.