"Blue-free" orange ZnO-related light-emitting diode based on a natural interface layer of Ga₂O₃ and ZnGa₂O₄

To fabricate a ZnO-related light-emitting diode (LED) with zero emission at blue wavelengths ("blue-free"), an ingenious strategy is employed. Specifically, for the first time to the best of our knowledge, a natural oxide interface layer, possessing remarkable visible emission potential, is introduced into the Au/i-ZnO/n-GaN metal-insulator-semiconductor (MIS) structure. The unique Au/i-ZnO/interface layer/n-GaN structure successfully eliminated the harmful blue emissions (400-500 nm) from the ZnO film, and the remarkable orange electroluminescence is mainly attributed to the impact ionization process of the natural interface layer at high electric field. It is worth mentioning that the device achieved ultra-low color temperature (2101 K) and excellent color rendering index (92.8) under electrical injection, indicating that the device could fulfill the requirements of electronic display systems and general illumination, and might even play unexpected roles in special lighting domains. The results obtained provide a novel and effective strategy for the design and preparation of ZnO-related LEDs.