Leafhopper Wing-Inspired Broadband Omnidirectional Antireflective Embroidered Ball-Like Structure Arrays Using a...

Leafhoppers (Thaia rubiginosa) actively coat their wings with embroidered ball-like secretory brochosomes, which act as antireflective structures to enhance camouflage against predators. Inspired by the leafhoppers, we report a scalable nonlithographic approach for self-assembling nonclose-packed embroidered ball-like hierarchical structure arrays. The resulting structures create a gradual refractive index transition at the air/substrate interface, thereby suppressing the optical reflection for wide viewing angles. Compared with a bare substrate, the average reflectance of the structured substrate in the whole visible spectral region is reduced from 9 to 3% at normal incidence, and the average reflectance of that is even reduced by ca. 22% as the incident angle reaches 75°. Moreover, the dependence of the height and the shape of the hierarchical structure on the omnidirectional antireflection performance is systemically evaluated in this research.