Fig. 5. Electrically tunable color pixels for reflective displays.

a Calculated color palettes by combining the measured reflectance spectra of the red, green, and blue metasurfaces with rotated meta-atoms in a 1:1:1 ratio. b Fabricated metasurfaces with rotated subpixels for (i) red, (ii) green, (iii) blue, and (iv) white colors. Under LP 0°, two colors are successfully mixed to produce (i) cyan, (ii) magenta, and (iii) yellow, while under LP 90°, the desired primary color is produced. The numbers in (b) are indicated in the color palettes in (a). The white arrows denote the L̂ axis. c Corresponding locations of the mixed colors on the CIE 1931 Chromaticity Diagram. (i), (ii), and (iii) refer to the samples in (b). The red line indicates the sRGB color gamut. d (i) Experimental demonstration of the electrical tunability of the color pixels using the fabricated metasurface in (b-ii) along with the LC cell. The color is modulated from green through to gray, and finally to magenta upon the application of electric field. (ii) Faux-colored scanning electron microscope image of the metasurface showing the subpixel layout for the measured sample. The scale bar represents 1 µm