Highly efficient white organic light‐emitting diodes with over 100 lm/W for next‐generation solid‐state lighting

High-performance two-unit all-phosphorescent white devices on a built-up light extraction substrate that comprised high-index materials were studied. As a result of suitable optical and electrical design, the device showed an extremely high efficacy of 114 lm/W at 1000 cd/m2. The device also showed 102 lm/W with long lifetime (LT70) of over 10,000 h at 3000 cd/m2. Outstanding external quantum efficiency of almost 50% was also achieved in a flat panel with an emissive area of 25 cm2. Color coordinates of the panel met the Energy Star® criteria of solid-state lighting with CIE (Commission Internationale de l'Eclairage) 1931 (x, y) = (0.477, 0.423), and the color rendering index was 81.