Subwavelength hollow nanopillar glass with gradient refractive index for ultra-low diffuse reflectance and anti-fogging

Title
Subwavelength hollow nanopillar glass with gradient refractive index for ultra-low diffuse reflectance and anti-fogging
Authors
문명운윤선미이영아박규철남산
Keywords
nanopillar; anti-reflection; anti-fogging
Issue Date
2020-02
Publisher
ACS Applied Materials & Interfaces
Citation
VOL 12, NO 5-6242
Abstract
Nanostructured glass with subwavelength hollow nanopillars of diameters of sub-65 nm was fabricated, showing high optical transmittance and ultralow diffuse reflectance. A simple process involving single-step plasma etching was used on a glass slide coated with a SiO2 sacrificial film. First, SiO2 nanodot structures were formed using plasma-induced anisotropic etching with CF4 plasma. The SiO2 nanodot array then became a secondary etching mask to form hollow nanopillars on the glass. The hollow structures formed at the upper part reaching up to the apex of the nanopillar had a lower solid fraction, while the lower part had a higher fraction. The refractive index (RI) gradually increased from 1.09 (near the value for air) to 1.42 (near the value for glass). Geometry-induced RI gradient enhanced light transmi, while it significantly reduced diffuse reflectance, particularly in the shorter wavelengths, thus suppressing the haziness or milky appearance of the nanostructured glass. Superhydrophilic and antifogging properties of nanostructured glasses and dental mirrored glasses were also demonstrated with water spraying and exhaled breath tests. Results showed that the wettability was enhanced in hydrophilicity and antifogging property by both the hydrophilic nature of the glass and the newly formed nanostructures. The nanostructured, superhydrophilic glass was also found to have easy cleaning nature against fine sand dust adhesion by simply blowing air or spraying water. Results of this study showed that such a hollow-pillared glass surface with gradient RI and special wettability could be applied in a variety of optical and optoelectronic applications requiring superwetting, such as optical windows for solar cell panels, display panels, light-emitting diodes, and medical devices even with curved surfaces.
URI
http://pubs.kist.re.kr/handle/201004/72352
ISSN
1944-8244
Appears in Collections:
KIST Publication > Article
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