Highly Efficient and Stable Light Emission from Two‐Dimensional/Three‐Dimensional ZnS/Perovskite Heterostructures

ABSTRACT The integration of three‐dimensional (3D) lead‐halide perovskites with two‐dimensional (2D) covalent semiconductors holds great promise for synergistically combining the exceptional optoelectronic properties of both material classes. However, their inherently dissimilar crystal structures, bonding characters, and formation energies have so far precluded the realization of coherent 2D/3D heterostructures. Here, we report a universal interfacial engineering strategy that enables the epitaxial growth of 2D chalcogenide/3D perovskite heterostructures by introducing an atomic sulfur bridge at the interface and synchronizing their crystallization kinetics. Sulfurization of the perovskite surface facilitates lattice matching with 2D ZnS, while ligand reprogramming—replacing the strongly coordinated Zn─O bond with a weakly coordinated Zn─N bond—tunes the growth rate of the chalcogenide layer to match that of the perovskite. This approach yields highly luminescent and water‐stable heterostructures across the visible spectrum, including blue, green, and red emissive ZnS/CsPbX 3 (X = Cl, Br, I) systems. Notably, the resulting red‐emitting ZnS/CsPbBrI 2 heterostructures achieve a photoluminescence quantum yield of 98.21% in solution and an external quantum efficiency of 28.6% in light‐emitting devices. Our work establishes a general paradigm for bridging ionic and covalent semiconductors, unlocking new opportunities for coherent heterostructure design in optoelectronic devices.