A near-infrared fluorescence enhancement strategy of amorphous silicon nanoparticles for night vision imaging and visualizing latent fingerprints†

Abstract

In recent years, broadband near-infrared (NIR) spectroscopy has attracted widespread research attention. However, the development of broadband NIR-emitting phosphors with superior thermal stability under excitation by near-ultraviolet or blue LED chips remains a challenge. Furthermore, silicon nanostructured materials exhibit unique photoelectric properties and environmentally friendly characteristics. While the study of crystalline silicon nanoparticles has garnered significant attention, research on amorphous structures remains limited. In this study, we synthesized amorphous silicon nanoparticles (a-Si NPs) with a wide near-infrared emission ranging from 600 nm to 1000 nm, achieved through a sol–gel derived polymer and a subsequent heat treatment process. The surface of a-Si NPs was effectively passivated by secondary annealing, resulting in enhanced near-infrared emission. Additionally, these nanoparticles displayed a NIR fluorescence emission peak at 812 nm with a full width at half maximum (FWHM) of 169 nm, alongside remarkable thermal stability. Consequently, the integrated NIR pc-LED device demonstrated outstanding night vision imaging capabilities. As an accurate fingerprint developer, it provides enhanced imaging on various substrates to reveal detailed features. The findings suggest that the a-Si NP phosphor has considerable potential for applications in night vision imaging and could make significant contributions to fingerprint detection technology. This research provides a valuable reference for the exploitation and further development of amorphous silicon-based optical materials.