Fig. 1. (a) Illustration of the proposed bilayer for realization of structural color on white silk. The white line represents silk, while the gray line represents silk coated by a Ti layer, and the dark red line represents silk coated with a Ti–Si bilayer structure. (b) SEM image of the Ti–Si bilayer on a single fiber. The Ti layer is marked by cyan, and the Si layer is marked by purple. (c) Photograph of cyan, olive, and brick red coatings on white silk. The thickness of the Si layer is 54 nm, 87 nm, and 120 nm with the Ti layer fixed at 100 nm. (d) Photograph of silk fabric with a Ti layer thickness of 100 nm. (e) Photograph of 105 nm Si layer on white silk.

Fig. 2. (a) Color palette of the structural colors as a function of the thicknesses of the Ti layer and Si layer. (b) Measured reflectance spectra of four bilayers with the Si layer thickness varied from 54 nm to 120 nm. The thickness of the Ti layer is fixed at 100 nm. For comparison, the blue, orange, and green spectra are offset up by 5%, 10%, and 15%, respectively. (c) Measured reflectance spectra of four bilayers with the Ti layer thickness varied from 25 nm to 100 nm. The thickness of the Si layer is fixed at 54 nm. (d) Corresponding colors of samples in the first row of (a) in the CIE 1931 chromaticity diagram. The thickness of the Si layer increases along the direction of the arrow. (e)–(g) Measured angle-resolved specular reflectance spectra of three samples. The thickness of the Si layer in (e), (f), and (g) is 64 nm, 80 nm, and 87 nm, respectively. The thickness of the Ti layer is fixed at 100 nm.

Fig. 3. Structural-colored Beijing Opera Facial Makeup patterns on white silk.

Fig. 4. (a) Photograph of cyan coatings on white silk before (original) and after rubbing and stretching treatments. (b) Photograph of cyan coatings on white silk with rubbing and stretching treatments. (c) Corresponding reflectance spectra for the cyan coatings on white silk before (original) and after rubbing and stretching treatments for 5 and 15 times. (d) Changes of the reflectance after rubbing and stretching treatments (Δ reflectance) for the Ti–Si bilayer and single Si layer.