Ergoktas, M. SaidBakan, GökhanKovalska, EvgeniyaLe Fevre, Lewis W.Fields, Richard P.Steiner, PietroYu, XiaoxiaoBalcı, Sinan2021-12-022021-12-0220211749-48851749-4893https://doi.org/10.1038/s41566-021-00791-1https://hdl.handle.net/11147/11820Optical materials with colour changing abilities have been explored for use in display devices(1), smart windows(2,3) or in the modulation of visual appearance(4-6). The efficiency of these materials, however, has strong wavelength dependence, which limits their functionality to a specific spectral range. Here, we report graphene-based electro-optical devices with unprecedented optical tunability covering the entire electromagnetic spectrum from the visible to microwave. We achieve this non-volatile and reversible tunability by electro-intercalation of lithium into graphene layers in an optically accessible device structure. The unique colour changing capability, together with area-selective intercalation, inspires the fabrication of new multispectral devices, including display devices and electro-optical camouflage coating. We anticipate that these results provide realistic approaches for programmable smart optical surfaces with a potential utility in many scientific and engineering fields such as active plasmonics and adaptive thermal management.eninfo:eu-repo/semantics/openAccessGraphene devicesArticle2-s2.0-8510361075810.1038/s41566-021-00791-1