A universal robust bottom-up approach to engineer Greta-oto-inspired anti-reflective structure

The Greta oto butterfly has transparent wings with extraordinary omnidirectional anti-reflection behavior, owing to unusual nano structures with random height and pitch/space distribution on its wing surface. The beauty and efficacy of such nanostructures are proven designs but difficult to reproduce en masse. Here, we establish a low-cost bottom-up approach by simply stacking monolayeraligned agitation-assisted deposition of silver nanowire (AgNW) meshes followed by deposition of various overcoats. Such AgNW meshes provide the template to grow nanostructures, imitating those on the Greta oto's wings that consist of randomly situated nanocones with controllable mean pitches and heights. The resulting nanostructure enhances anti-reflections in both SiO2/AgNW and VO2/AgNW systems, which showed reduced omnidirectional reflectance up to 33% and 70%, respectively. Furthermore, the VO2/AgNW system exhibits enhanced luminous and infrared transmittance without sacrificing solar modulation. Our robust bottom up approach provides a simpler alternate non-lithographic way to economically produce controlled biomimetic anti-reflective nano structured coatings.

Automated summary

The Greta oto butterfly's transparent wings with unique nanostructures exhibit extraordinary anti-reflection behavior, which researchers have successfully replicated using a low-cost bottom-up approach. The resulting nanostructures significantly reduce omnidirectional reflectance, showing promise for practical applications in producing biomimetic anti-reflective coatings.