Halide Perovskite Heterostructures for High-Performance Light-Emitting Diodes.

Metal halide perovskites have emerged as highly promising candidates for the emissive layer in next-generation light-emitting diodes (LEDs) due to their narrow emission linewidths, high photoluminescence quantum yields, and tunable emission wavelengths. Achieving high-performance perovskite LEDs (PeLEDs) requires the emissive layer to possess efficient radiative recombination, low defect density, minimal ion mobility, and effective carrier confinement. Perovskite/perovskite heterostructure (PPHS) offers a compelling approach for engineering emissive layers with these desired attributes, owing to their ability to passivate surface defects, tailor bandgaps, and suppress ion migration. PeLEDs based on PPHS have demonstrated superior performance compared to single-phase devices, particularly in terms of external quantum efficiency and operational stability. This review provides a comprehensive overview of the typical PPHS architectures applied in PeLEDs, including vertical, lateral, and bulk configurations. We discuss representative fabrication strategies and the associated optoelectronic properties of these heterostructures, highlighting the mechanisms by which they enhance device efficiency and stability. Finally, we explore the remaining challenges and prospects for the application of PPHS in PeLEDs and other luminescent technologies.