Enhanced Electroluminescence from ZnO Quantum Dot Light‐Emitting Diodes via Introducing Al₂O₃ Retarding Layer and Ag@ZnO Hybrid Nanodots

Abstract Short‐wavelength light‐emitting diodes (LEDs), a prevalent research topic in modern optoelectronics, have attracted considerable attention in recent years because of their vast application potential in both civil and military domains. Herein, blue‐violet LEDs are constructed via a spin‐coating solution‐processed ZnO quantum dots (QDs) onto p‐GaN: Mg wafers. By inserting a thin Al₂O₃ dielectric retarding layer into the ZnO QDs side, electrons injected from ITO cathode are effectively slowed and detained in the QDs emissive layer, resulting in a ≈30‐fold improvement of near‐UV electroluminescence intensity from this p‐GaN/ZnO QDs/Al₂O₃/ZnO QDs LED. Furthermore, by replacing pure ZnO QDs with Ag@ZnO hybrid nanodots (synthesized through a simple one‐step wet chemical route) as the electron transport layer, the device electroluminescence intensity is further increased. Time‐resolved and temperature‐dependent spectroscopy reveals that both the spontaneous emission rate and internal quantum efficiency of the ZnO QDs active layer are simultaneously increased as a result of the exciton‐localized surface plasmon resonant coupling, which leads to the observed blue‐violet electroluminescence enhancement.