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Article RSE 14002102

Broadband and Crack-Free Antireflection Coatings by Self-Assembled Moth Eye Patterns

Article

ACS Applied Materials & Interfaces dx.doi.org/10.1021/am500687f, pp. 5827-5834, Marzo-2014.

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G. Timo´ (RSE SpA) , F. Trespidi (RSE SpA), F. Galeotti (ISMAC-CNR), M. Pasini (ISMAC-CNR)

SOLARE 2014 - Electricity from solar energy

Broadband quasi-omnidirectional antireflective (AR) structures have been studied. The glass transmission is improved by 2% on a single surface. The coating works for a wide range of angle of incidence between 0 ° and 50 ° and for optical wavelengths ranging from the visible to the near infrared spectrum.

We report broadband and quasi-omnidirectional antireflective (AR) structures inspired to the nipple arrays of moth eyes. These nanocoatings, based on thin elastomeric films, are prepared by simple self-assembly processing of a co-polymer specifically designed to this purpose, and PDMS replica molding. Typically, their surface is covered by a compact distribution of hemispherical nanodomes of about 250 nm in diameter and about 100 nm in height. When these novel nanostructures are applied on a single glass surface, a maximum of 2% transmission enhancement (equivalent to a 50% reduction of the reflected component) towards wavelengths ranging from visible to near IR region is obtained.

A considerable AR power is observed also at a wide range of incident angles ranging from normal to 50°. These properties could be attributed to an optimized graded refractive index profile resulting from the randomly distributed and close-packed nanodomes. Moreover, thanks to their elastomeric nature, these crack-free films can be easily applied on glass, as stickers, and periodically replaced, thus offering the possibility of easy dirt removal from an optical device.

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