Noniridescent structural colors are superior in photostability and energy efficiency as compared to pigments and bioluminescence counterparts. However, it is challenging to facilely and massively fabricate nanofilms with noniridescent structural colors spanning the full spectrum of visible light. Here, a one-pot synthesis strategy is demonstrated to prepare free-standing dual-layer nanofilms with different refractive indices in each layer via a combination of mussel-inspiration and silication at the air/water interface. XPS, 2D GISAXS, and ellipsometry were used to verify the dual-layer but interface-free structure with different refractive indices. Moreover, the full spectrum of noniridescent structural colors has been achieved by precisely tailoring the film thickness of each layer through regulating the kinetics of the two reactions. This strategy offers flexibility for further on-demand patterning because of the self-sealing property of the dual-layer nanofilms, which has great application potentials in flexible displays and sensors.
