Color/Spectral Stability of Mixed Halide Perovskite Light‐Emitting Diodes

Abstract Structuring metal halide perovskites with mixed halide anions is a promising strategy for attaining the desired bandgap and emission color for technological applications such as electroluminescent (EL) light‐emitting diodes (LEDs) and ultrahigh‐definition displays. However, these mixed halide perovskites suffer from severe EL spectral stability issues. During device operation, homogeneously mixed halide perovskite phases are prone to form halide‐segregated domain phases with spatially inhomogeneous bandgap and emission color, which hinders practical use of perovskite LEDs (PeLEDs). In this review, a comprehensive survey is performed about the underlying driving forces for phase segregation, and representative strategies are discussed for the development of color/spectral stable mixed halide PeLEDs. Finally, the future directions and prospects are outlined regarding further enhancement of the color/spectral stability of mixed halide PeLEDs.