Hiroto Yamana, Haruki Tanaka, Hiroshi Sugimoto, Minoru Fujii
Inkjet printing of silicon nanoparticle (Si NP) inks and their inherent color asymmetry in reflection and transmission is demonstrated. The optical response of Si NP-dispersed films was initially analyzed using Monte Carlo simulations, which elucidated the physical origin of the asymmetric color appearance. Guided by these theoretical insights, water-based Si NP inks incorporating an acrylic resin were formulated and applied to inkjet printing. The printed films exhibited vivid structural colors with pronounced differences between their reflective and transmissive hues. Furthermore, multicolor patterns with tunable optical asymmetry were produced by employing Si NPs of different diameters. These results highlight the potential of Si NPs as scalable structural-color pigments for multicolor dichroic decorations in applications such as art, anti-counterfeiting, and semitransparent smart windows.