Extremely-Fine Color Printing by 2D Materials with the Synergetic Effects of Fabry–Pérot Cavity and Exciton Absorption

Structural colors based on plasmonic and dielectric nanostructures have become attractive alternatives over adsorbed dyes or pigments in high resolution color printing. The color resolution is determined by the fine-tuning in optical resonance peak of the nanoresonators, and is strongly restricted by the limited geometrical dimensions. Here, 2D materials including MoS₂ and GaSe are demonstrated as unique materials which generate full color gamut, vivid, and extremely-fine tuning colors. Attributed to the atomic thickness change in Fabry–Pérot cavity length and exciton-induced additional absorption, the optical resonance peak could be tuned in the subnanometer level. As a result, the converted xy values from the reflection spectra on the CIE 1931 diagram show an average step of 0.0019 (0.0052) along x-axis (y-axis), with a resolution an order of magnitude higher than current plasmonic and dielectric nanoresonators. The suitability of 2D materials on submicrometer color printing is further demonstrated by fabricating color patterns using GaSe flakes and the printed image has resolutions of 50 800 lines-per-inch (LPI) and 25 400 dots-per-inch (DPI) without color mixing. The color patterns are selectively recognized by different visible light with a wavelength resolution of 20 nm. 2D materials provide new platforms for high-resolution printing, anticounterfeiting, and high-density spectrally encoded storage.