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 Sn²⁺. Here, we demonstrate a versatile buried-interlayer strategy to effectively regulate the crystallization and suppress the Sn²⁺ 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.