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

• Published in: Cell reports physical science Vol. 2; no. 7; p. 100479
• Main Authors: Vu, Tuan Duc, Cao, Xun, Hu, Hebing, Bao, Jiaxin, Cao, Tun, Hu, Jiangfeng, Zeng, Xianting, Long, Yi
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 21.07.2021
• Subjects: biomimetic; monolayer assembly; omnidirectional anti-reflection; smart window; vanadium dioxide; smart window; vanadium dioxide; monolayer assembly; omnidirectional anti-reflection; biomimetic
• ISSN: 2666-3864; 2666-3864
• DOI: 10.1016/j.xcrp.2021.100479

The Greta oto butterfly has transparent wings with extraordinary omnidirectional anti-reflection behavior, owing to unusual nanostructures 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 monolayer-aligned 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 nanostructured coatings. [Display omitted] A bottom-up approach is reported to fabricate a biomimetic anti-reflective systemThe final structure consists of random nanopeaks similar to those on Greta oto wingsThe method of fabrication is applicable to multiple systems, namely SiO2 and VO2SiO2/AgNW and VO2/AgNW systems enhance anti-reflection up to 33% and 70%, respectively Vu et al. fabricate anti-reflective multilayer systems by depositing thin films on monolayer AgNW templates. The resulting surface morphology resembles the wing of Greta oto. The fabricated biomimetic structures exhibit universal omnidirectional anti-reflective capabilities on both SiO2/AgNWs and VO2/AgNWs, whereas the latter system shows additional improvement on thermochromic performance.