Overcoming the Structural Incompatibility Between White, Black, and Vibrant Hues in Dynamic Structural Colors

Nature typically creates white and black structural coloration through disordered, dense assemblies of scatterers and absorbers that scatter and absorb light uniformly across the visible range, respectively. However, this approach conflicts with structural coloration designs for vibrant hues, which use ordered and uniform nanostructures. This structural discrepancy presents a challenge when trying to incorporate white and black alongside other colors in dynamic structural colors. Herein, a dynamic reflective coloration strategy is demonstrated, capable of switching between white, black, and other hues from ordered nanostructures. This is accomplished by exploiting reversible Cu electrodeposition within the slits of a nanograting and observing its cross-polarized reflection, resolving colors from the grating birefringence. By electrochemically modulating the Cu thickness, birefringence is selectively activated, mixed, and eliminated from photonic (Rayleigh-Wood) and near-plasmonic resonances, producing blue, orange, white, and black colors. These results offer a pathway to dynamic white and black structural coloration compatible with ordered nanostructures.