In Situ Construction of Optical Resonators from MXene Inks for Highly Modifiable and Scalable Structural Colors

Structural colors offer distinct advantages over traditional chemical colors (such as pigments and dyes), including high saturation, resistance to fading, and environmental friendliness. However, unlike traditional dyes or pigments that allow for Structural colors offer distinct advantages over traditional chemical colors (such as pigments and dyes), including high saturation, resistance to fading, and environmental friendliness. However, unlike traditional dyes or pigments that allow for arbitrary color adjustments during the coloring process, current structural color surfaces lack flexibility in control, as their colors are difficult to reprocess or adjust once formed. Here, we propose a convenient approach for the high-throughput fabrication of structural color films with high tunability using a single type of ink containing large, geometrically anisotropic 2D materials such as MXene nanosheets. The method involves the self-assembly of these MXene nanosheets onto a predesigned substrate surface to form a Fabry–Perot (F–P) resonance cavity using a straightforward spraying technique. By optimizing the ink formulation and spraying conditions, the F–P resonance structural colors generated through spray-assisted self-assembly allow for real-time, large-scale modifications in situ, with hue variations approaching 360° in just 70 s. Furthermore, this strategy offers a customizable platform capable of generating a rich color palette, covering a broad spectrum within the CIELAB color space and even rivaling commercial color printing standards. These capabilities have enabled the execution of a wide range of applications, from intricate patterns with single-pixel dimensions as small as 70 μm to uniform, meter-scale color films (0.3 × 2 m 2 ).