Dragonfly-Wing-Inspired Inclined Irregular Conical Structures for Broadband Omnidirectional Antireflection Coatings

Blue-tailed forest hawk dragonfly (Orthetrum triangulare) wings exhibit a high transparency at wide viewing angles. The broadband omnidirectional antireflection behaviors of dragonfly wings result from the random arrangement of inclined irregular conical structures. In this study, a scalable colloidal lithography technique is developed for spin-coating randomly packed silica colloids, which serve as direct structural templates for patterning subwavelength inclined conical structures on substrates. The dragonfly-wing-inspired structures feature an omnidirectional antireflection performance over the whole visible spectral range and generate superhydrophobicity after surface functionalization. The dependencies of the inclination and height of the conical structures on the antireflection performance and self-cleaning property are also systemically studied in this research.