A Bioinspired Random Nanosheet Film for Broadband Spectral Modulation and Switchable Infrared Stealth.

Efficient spectral modulation and photothermal management can significantly enhance the multifunctional integration of intelligent optical devices. However, the selective modulation ability of materials to the spectrum hinders their application in different scenarios or needs. Here, inspired by the transparent wings of Haetera piera, a random nanosheet film with spectral modulation and flexible switching properties is fabricated on FTO glass. Remarkably, the film reduces the reflectivity by 6-13% compared with the initial FTO glass in the visible spectrum (0-60° incident angles) and lowers ultraviolet transmittance by approximately 15%. The antireflection characteristics in the visible band and the low transmittance in the ultraviolet band indicate that the nanosheets have a certain spectral modulation ability. By applying a voltage of 1.5 V, the transparent film turns into a colored state, reducing the mid-infrared emissivity by 50% and increasing reflectivity by 45%, thus achieving infrared stealth. This work provides key insights for energy, military, and optoelectronics, with significant application prospects.