Stepped‐Dimensional 2D/3D Tin‐Based Perovskites for High‐Efficiency Light‐Emitting Diodes

Tin (Sn)‐based perovskite near‐infrared (NIR) light‐emitting diodes (LEDs) show great potential for applications in night vision, biomedical sensing, and optical communications. However, their performance remains limited by uncontrolled crystallization and the facile oxidation of Sn 2+ . Here, we demonstrate a versatile buried‐interlayer strategy to effectively regulate the crystallization and suppress the Sn 2+ oxidation by constructing a two‐dimensional/three‐dimensional (2D/3D) heterodimensional structure. We reveal that strong interactions between the buried ligand layer, the perovskite precursor, and the underlying hole‐transport layer promote rapid nucleation, retard crystal growth, and induce a vertical dimensional gradient, leading to reduced defect density and enhanced radiative recombination. As a result, NIR Sn‐based perovskite LEDs achieve a record external quantum efficiency of 13.7% with a radiance of 103 W sr −1 m −2 . Furthermore, the buried‐interlayer strategy enables dual‐functional Sn‐based perovskite devices capable of both efficient light emission and photodetection, which are successfully integrated into a compact heart‐pulse monitoring system. Our work suggests a synergistic crystallization and dimensional‐regulation strategy for achieving high‐performance Sn‐based perovskite optoelectronic devices.