Rewritable large-area structural color films based on Mie scattering of Cu₂O@SiO₂ microspheres

Abstract

Structural colors are generated by some different mechanisms. Here, we prepared a kind of large-area structural color films using Cu₂O@SiO₂ microsphere as the coloring units. The film is prepared by infusing PDMS into a disordered structural template assembled from Cu₂O@SiO₂ microsphere, followed by thermal curing and peeling. The disordered Cu₂O@SiO₂ thin layers embedded in the film are obtained by a spraying method, which can generate vivid noniridescent structural colors due to the strong Mie scattering of Cu₂O@SiO₂ microsphere. Meanwhile, Cu₂O@SiO₂-polydimethylsiloxane composite films show excellent chemical stability and mechanical properties. Dynamic tuning of the structural color is achieved by covering the film surface with a liquid layer, which modulates the interfacial medium environment and alters the relative refractive index contrast between the medium and the scattering units. Notably, when applied as structural color writing paper, the film demonstrates good reversible writing and erasing performance. The simple color-changing mechanism and ease of large-area fabrication make it a promising candidate for rewritable colored paper applications.