High-CRI White Light-Emitting Diodes With Long T50 Lifetime From Perovskite-Inspired CsCu2I3 Halide

Copper(I)-based ternary halide CsCu2I3 has attracted extensive attention in recent years due to its outstanding photophysical properties and great potential in application of high-performance white light-emitting diodes (WLEDs). Herein, we successfully introduced vacuum evaporation to prepare uniform, pinhole-free CsCu2I3 film as the active layer for the ${n}$ -GaN/CsCu2I3 heterostructured LEDs. WLEDs, with standard CIE of (0.334, 0.327) and color rendering index (CRI) as high as 93.3, were realized with the help of a thin electron-blocking polymethyl methacrylate interlayer. The WLEDs showed extraordinary stability with operational lifetime ( $\text{T}_{{50}}{)}$ as high as 239 h in the open air ambient. Our results provide a feasible way to produce high-CRI WLEDs based on perovskite-Inspired lead-free halides via vacuum evaporation.