Figure 3From: The influence of type-I and type-II triplet multiple quantum well structure on white organic light-emitting diodesThe schematic energy level diagram of WOLEDs with the portion of EMLs. (a) device A. (b) device B. (c) device C. Black circle and white circle express electron and hole, respectively. The numbers indicate the LUMO and HOMO energies relative to vacuum (in eV). Here, LUMO and HOMO are cited from [18–20].Back to article page