Memory-Enabled Quantum-Dot Light-Emitting Diodes.

Quantum-dot light-emitting diodes (QLEDs) with memory capability can provide multifunctional integration properties in on-chip and intelligent electronic applications. Herein, memory properties are achieved by inserting a tungsten oxide (WO x ) film between the ZnO electron-transporting layer and cathode. Pentavalent tungsten ions (W 5+ ) in this nonstoichiometric WO x film can be oxidized to W 6+ by storing holes, inducing significant electrons in the adjacent ZnO layer. Hole storage in the WO x layer suppresses electron injection into the quantum dot emissive layer, hence reducing electroluminescence intensity on the onset stage of the QLEDs. This operation-history correlation for the electroluminescence intensity means a memory behavior for the QLEDs. Furthermore, the power efficiency of the devices is greatly improved after inserting the WO x layer due to electrical field-dependent self-adaptive electron injection into the quantum dots (QDs). We anticipate this type of QLEDs have potential applications in on-chip integration applications, such as the optical computing field and storage.