Bio-Inspired Bright Non-Iridescent Structurally Colored Nanopigments Featuring Additive Color Mixing Performance

Abstract

Owing to the unique features of high chemical and photostability, structurally colored materials can potentially replace organic dyes and pigments in many applications. The most common fabrication method of structural color materials is the “bottom-up” self-assembly approach. However, the assembled structures are easily damaged by external forces, leading to color fading or even disappearance. Therefore, it is still a challenge to fabricate structural colors that mimic the appearance of absorbing pigments without assembly processes. Inspired by the Steller's jay, non-iridescent structurally colored nanopigments are created, which are composed of hollow SiO2 (H-SiO2) microspheres with amorphous carbon on the inner wall of the shell and disordered metasurfaces on the shell layer. It is shown that the color originates from the synergistic effect of the disordered metasurfaces and the amorphous carbon layer, which can produce strong coherent scattered light and effectively absorb incoherently scattered light, respectively. Amazingly, the H-SiO2 microspheres can maintain their structural colors even after grinding or being dispersed in water. What's more, through the additive color mixing of two base colors and precise tuning of their ratios, gradient structural colors that spanning the visible spectrum can be achieved. These features indicate promising prospects for the designed nanopigments.