Tunable Near‐Infrared Emission from Silicon Nanocrystals in Amorphous Silicon Dioxide: Structural Evolution and Multifunctional Applications

Abstract Broadband near‐infrared (NIR) luminescent materials are crucial in near‐infrared smart devices and optical communications, but conventional cadmium‐based NIR materials have toxic risks. Biocompatible silicon nanomaterials with tunable emission wavelengths offer a promising alternative. Here, silicon nanocrystal composites (Si NCs/SiO 2 ) with broadband NIR emission spanning from 600 to 1000 nm are synthesized through precise control of the microstructure of silicon polymer precursors. Si NCs/SiO 2 exhibit a unique nano‐embedded microstructure, and their NIR photoluminescence quantum yield reaches up to 28.1%. Moderately reducing the precursor water content effectively enhances Si NCs growth quality, photoluminescence, and stability. Comprehensive characterization elucidates the critical role of the synergistic effect between quantum confinement and radiative recombination at the suboxide interface in the NIR emission. Furthermore, Si NCs/SiO 2 retains over 90% of its luminescent intensity at an elevated temperature of 328 K, demonstrating excellent thermal stability and resistance to thermal quenching. Near‐infrared phosphor‐converted light‐emitting diodes (NIR pc‐LEDs) fabricated using Si NCs/SiO 2 exhibit stable emission under high driving currents and demonstrate superior performance in nondestructive evaluation, biological imaging, information encryption, and night vision imaging. This work establishes a design framework for environmentally friendly near‐infrared luminescent materials and underscores the potential of silicon‐based nanomaterials for practical applications.