Figure 3

Schematic illustrations of antinode and EML positions for yellow and blue emissions in tandem and single-stack WOLEDs. (a) Tandem WOLED that easily fits both of blue and yellow EMLs to their respective antinode positions through spatially separated two recombination zones by charge generation layer (CGL), (b) Single-stack WOLED that cannot fit yellow EML to its antinode position, (c) Single-stack WOLED that fits both of blue and yellow EMLs to their antinode positions by changing interference condition of yellow and blue emissions in the WOLED through ITO thickness tuning.