Exciplex interlayer switch surface charge effect on ultra-thin non-doping WOLEDs

The regulation of charge and exciton distribution play a significant role in ultra-thin non-doped white organic light-emitting diodes (WOLEDs). Herein, the exciplex is selected as an interlayer (IL) switch to adjust the charge balance and regulate exciton distribution in ultra-thin non-doped WOLEDs. The optimal device achieved a maximum external quantum efficiency (EQE) of 22.42 %, a maximum current efficiency of 63.41 cd/A and a maximum power efficiency of 83.04 lm/W. The time‐resolved photoluminescence of different exciplexes has been systematically investigated to reveal the intrinsic luminance mechanism of high-efficiency WOLEDs. In addition, kelvin probe force microscopy (KFPM) results provide new insights in exciplex interlayer switch surface charge effect. These results demonstrate the potential of exciplex IL for exciton confinement, charge balance and carrier transport, which prevent energy loss and reduce triplet-triplet annihilation. Therefore, the utilization of exciplex IL is a promising approach for the development of next-generation WOLEDs.