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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. [ABSTRACT FROM AUTHOR]

Phosphors play an extremely important role in solid-state lighting and full-color displays. Recently, it has been observed that their properties can be extensively utilized in the field of anti-counterfeiting. For the study of innovative anti-counterfeiting materials, the selection of high-quality matrix materials is indispensable. In this work, green AlN:Eu2+ phosphors are synthesized by the direct nitriding method, and their physical structure, micro-morphology, elemental composition, and photoluminescence properties are systematically investigated at different synthesis temperatures and doping concentrations. The results show that the peak emission of AlN:0.05Eu2+ occurs at 525 nm at a synthesis temperature of 1400 °C, and the fluorescence intensity retains 53.5% of its room temperature value when the test temperature is increased to 110 °C. The synthesized phosphors are dispersed in thermoplastic polyurethane (TPU) to create a UV-excited, flexible anti-counterfeiting film. The AlN:Eu2+@TPU anti-counterfeiting film exhibits excellent light transmission, flexibility, stretchability, and water resistance. When a current of 50 mA is applied, the green LED encapsulated with AlN exhibits high color purity. The CIE coordinates of the white LED are (0.32, 0.34), with a relevant color temperature (CCT) of 5727 K and a color rendering index (Ra) of 85.9. Overall, the results suggest that AlN:Eu2+ phosphors possess significant potential for realizing multidimensional applications in lighting displays and anti-counterfeiting. [ABSTRACT FROM AUTHOR]

The crystallization behavior of halide perovskites is of great significance. Fractal structures, featured by self-similarity between local morphology and global structures, have consistently captivated scientists' interest across diverse disciplines. In this study, we realized the fractal patterns in lead-free zero-dimensional (0D) Cs2InBr5(H2O) perovskites. By depositing saturated precursor droplets on silicon or glass substrates, we initiated nucleation and crystallization of 0D Cs2InBr5(H2O) crystals on the liquid's upper surface. As the solution evaporated, the remaining high-concentration solution formed self-similar fractal patterns beneath the Cs2InBr5(H2O) crystals. This anisotropic growth mechanism imparted a unique self-assembly behavior to 0D Cs2InBr5(H2O). Additionally, X-ray diffraction results confirmed distinct preferential orientations of the fractal patterns. The findings of this work provide valuable insights into the controlled crystallization behavior of lead-free perovskites and inspire further exploration of novel optoelectronic properties arising from such a unique fractal pattern. [ABSTRACT FROM AUTHOR]

Homogeneous colloidal silicon nanoparticles (Si NPs) were synthesized at ambient temperatures. With the incorporation of poly-(vinyl alcohol) (PVA), the absolute photoluminescence quantum yield (APLQY) and photochromic stability of the fluorescent colloid (p-Si NPs) were significantly enhanced compared to Si NPs. In the absence of additional high-temperature treatments or doped fluorophores, colloid p-Si NPs exhibit blue-green luminescence under ultraviolet excitation. Subsequently, the highly dispersed p-Si NPs solution underwent heat treatment, resulting in a suitable viscosity for direct screen printing. The printed pattern appears transparent under natural light and blue-green under ultraviolet light, showing good invisibility. These patterns possess notable characteristics, including high adhesion, uniformity, stain resistance, and excellent stability. Consequently, they can be efficiently developed for anticounterfeiting labels and printing inks. Notably, the ink also has the characteristics of low toxicity and substantial biocompatibility, offering promising avenues for the synthesis and application of environmentally friendly benign nano anticounterfeiting ink. [ABSTRACT FROM AUTHOR]