Development of a High‐Performance, Anti‐Fouling Optical Diffuser Inspired by Morpho Butterfly's Nanostructure

Abstract The realization of high‐performance, anti‐fouling optical diffusers is crucial for various light applications. However, this remains a major challenge for conventional diffusers because of the optical inefficiency of multiple scattering and/or surface reliefs vulnerable to contamination. Inspired by the disordered nanostructure of Morpho butterflies that enables the simultaneous fulfillment of wide‐angle diffraction, low color dispersion, and superhydrophobic self‐cleaning ability due to the lotus effect, this study demonstrates a novel Morpho‐type diffuser with high optical performance and anti‐fouling properties. Surface nanopatterns of the diffuser are newly designed to realize homogeneous light diffusion, combined with the suitable material selection of polydimethylsiloxane (PDMS) to induce the lotus effect. Consequently, the following properties are simultaneously achieved: i) high transmittance ≈90%; ii) wide‐angle diffusion (full width at half maximum ≈80°) with high spatial uniformity; iii) low dispersion; iv) high controllability of anisotropy; and v) anti‐fouling properties. Moreover, vi) the applicability of surface protection is demonstrated by exploiting the high flexibility/adhesivity of PDMS. These capabilities surpass other diffusers, and therefore the presented diffuser is promising for a wide range of applications such as lighting, displays, daylight harvesting, optoelectronics, and medicine.