Achieving low driving voltage and high-efficiency afterglow organic light-emitting diodes through host–guest doping

Achieving afterglow organic light-emitting diodes (OLEDs) that exhibit the organic ultralong room temperature phosphorescence (OURTP) emission after switching off the applied voltage is highly attractive. However, it is difficult to obtain appropriate emitting layers that are of excellent charge transport ability and OURTP properties simultaneously to fabricate highly efficient afterglow OLEDs. Here, we report an easy but effective strategy to construct afterglow OLEDs via host–guest doping by adopting the excellent carrier transporting materials as rigid host and the commendable OURTP emitters as guest. The resultant green afterglow OLEDs exhibit the state-of-the-art maximum external quantum efficiency, luminance, and OURTP lifetimes of up to 1.47%, 743 cd m⁻², and 356 ms, respectively, with the low turn-voltage of 4.4 V. Due to the inherent stable afterglow properties and outstanding carrier transport ability of the emitting layer, the OLEDs show admirable afterglow emission stability with the intensity and lifetimes keeping almost the same for more than ten repeated voltage pulses. The current work paves the way to develop highly efficient and stable afterglow OLEDs by host–guest doping.