Abstract: Inspired by cicada wings, a flexible film with self-cleaning and broadband antireflection properties was fabricated with a rapid,
straightforward and cost-effective method. The cicada wing was selected as the original template, and a polymethyl methacrylate (PMMA)
negative replica was obtained by evaporation solvent process. The original template was directly peeled off. Subsequently, the polydimethylsiloxane
(PDMS) was spread in the as-prepared PMMA negative replica. After curing and peeling processes, the PDMS positive
replica was manufactured successfully. The morphologies and performances of cicada wings were perfectly inherited by the PDMS positive
replica. What is more, the excellent optical property of cicada wing was investigated experimentally and theoretically. Compared with
flat PDMS film, the average reflectivity of structural PDMS film was reduced from 9% to 3.5% in the wavelength range of 500 nm –
900 nm. These excellent antireflection properties of bio-inspired antireflection film can be attributed to the nanostructures which achieve a
gradient refractive index between air and the materials, and the mechanism of the antireflection properties was revealed via effective
medium theory. Besides, the bio-inspired broadband antireflective film exhibited superhydrophobic property after the surface treatment (a
152.1? water contact angle), and it also displayed satisfactory flexibility. This work provided a universal method to fabricate the exquisite
biological structures, realizing the transfer of structure and function. Moreover, the multifunctional antireflection film exhibited the potential
value for applications in optical communications, flexible display screens, and anti-dazzle glasses. 

Key words: antireflection, self-cleaning, multifunctional surface, flexible film, biomimetic fabrication