Poly(vinyl alcohol)-Modified Colloidal Silicon Nanoparticles for Flexible Screen Printing Inks and Anticounterfeiting Applications

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.