Near‐Infrared and Short‐Wave Infrared Two‐Dimensional PbSe/PbS Heterostructures With Lead Halide Perovskite Passivated Surface for Light‐Emitting Diode

Near‐infrared (NIR) light sources based on colloidal two‐dimensional (2D) semiconductor heterostructures hold significant promise for biomedical imaging and optical communications, yet their practical deployment is constrained by surface trap‐mediated nonradiative decay and poor solid‐state stability. Herein, we report a solution‐processable interfacial passivation strategy for PbSe/PbS core/shell and core/wings nanoplatelets using a mixed‐halide CsPb(Br/I) 3 perovskite matrix. Comprehensive structural and spectroscopic analyses demonstrate that the perovskite overlayer effectively suppresses surface defects, yielding a 2.3–2.7× enhancement in relative photoluminescence intensity and extending emission lifetimes to 3.8 ns while preserving the intrinsic NIR/short‐wave infrared (SWIR) emission profiles. When integrated into solution‐processed devices, the passivated films enable down‐conversion light‐emitting diodes (LEDs) with radiance of up to 0.026 W/sr/m 2 under 450 nm excitation, as well as charge‐injection LEDs exhibiting a low turn‐on voltage of ~4.1 V and electroluminescence at 1310 and 1610 nm. This work establishes a robust surface‐engineering framework that bridges colloidal 2D lead chalcogenide heterostructures with practical solid‐state optoelectronics, paving the way for novel NIR/SWIR emitters.