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Optically Graded Ultra Dark Absorber for Visible and Near-infrared Wavelength Range

Near perfect absorbers find application in many areas including solar cells, energy harvesting and antireflection coatings for space applications. Here we report the use of optical gradation concept to fabricate a near perfect absorber on etched Si wafer. As a proof of concept, 99.4% absorption is a...

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Autores principales: Agnihotri, Prabhat K., Ghai, Viney, Singh, Harpreet
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6098028/
https://www.ncbi.nlm.nih.gov/pubmed/30120373
http://dx.doi.org/10.1038/s41598-018-30844-5
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author Agnihotri, Prabhat K.
Ghai, Viney
Singh, Harpreet
author_facet Agnihotri, Prabhat K.
Ghai, Viney
Singh, Harpreet
author_sort Agnihotri, Prabhat K.
collection PubMed
description Near perfect absorbers find application in many areas including solar cells, energy harvesting and antireflection coatings for space applications. Here we report the use of optical gradation concept to fabricate a near perfect absorber on etched Si wafer. As a proof of concept, 99.4% absorption is achieved in the broad range of 300 nm to 2000 nm. Moreover, absorption capacity of optically graded surface remains higher than 99% up to beam incident angle of 50°. While carbon nanotubes (index ~1.1) are used as top layer, subsequent layers with increasing optical index across the thickness are chosen so as to satisfy zero reflection condition on multilayered assembly. Inward bending of incident beam and total internal reflection of reflected beam caused due to optical index gradient contributes to absorb the incident beam more efficiently. In addition, multiple scattering of incident beam due to the presence of multiscale feature size in graded assembly helps to absorb shorter as well as longer wavelengths of incident light. The graded assembly shows contact angle of 160° with roll-off angle equal to 5° implying that the graded absorber is not only super black but also superhydrophobic and self-cleaning in nature. The combination of properties shown by the super absorber makes it very attractive, especially for next generation solar cells to harness energy in the wavelength range of 1000 nm to 2000 nm.
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spelling pubmed-60980282018-08-23 Optically Graded Ultra Dark Absorber for Visible and Near-infrared Wavelength Range Agnihotri, Prabhat K. Ghai, Viney Singh, Harpreet Sci Rep Article Near perfect absorbers find application in many areas including solar cells, energy harvesting and antireflection coatings for space applications. Here we report the use of optical gradation concept to fabricate a near perfect absorber on etched Si wafer. As a proof of concept, 99.4% absorption is achieved in the broad range of 300 nm to 2000 nm. Moreover, absorption capacity of optically graded surface remains higher than 99% up to beam incident angle of 50°. While carbon nanotubes (index ~1.1) are used as top layer, subsequent layers with increasing optical index across the thickness are chosen so as to satisfy zero reflection condition on multilayered assembly. Inward bending of incident beam and total internal reflection of reflected beam caused due to optical index gradient contributes to absorb the incident beam more efficiently. In addition, multiple scattering of incident beam due to the presence of multiscale feature size in graded assembly helps to absorb shorter as well as longer wavelengths of incident light. The graded assembly shows contact angle of 160° with roll-off angle equal to 5° implying that the graded absorber is not only super black but also superhydrophobic and self-cleaning in nature. The combination of properties shown by the super absorber makes it very attractive, especially for next generation solar cells to harness energy in the wavelength range of 1000 nm to 2000 nm. Nature Publishing Group UK 2018-08-17 /pmc/articles/PMC6098028/ /pubmed/30120373 http://dx.doi.org/10.1038/s41598-018-30844-5 Text en © The Author(s) 2018 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
spellingShingle Article
Agnihotri, Prabhat K.
Ghai, Viney
Singh, Harpreet
Optically Graded Ultra Dark Absorber for Visible and Near-infrared Wavelength Range
title Optically Graded Ultra Dark Absorber for Visible and Near-infrared Wavelength Range
title_full Optically Graded Ultra Dark Absorber for Visible and Near-infrared Wavelength Range
title_fullStr Optically Graded Ultra Dark Absorber for Visible and Near-infrared Wavelength Range
title_full_unstemmed Optically Graded Ultra Dark Absorber for Visible and Near-infrared Wavelength Range
title_short Optically Graded Ultra Dark Absorber for Visible and Near-infrared Wavelength Range
title_sort optically graded ultra dark absorber for visible and near-infrared wavelength range
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6098028/
https://www.ncbi.nlm.nih.gov/pubmed/30120373
http://dx.doi.org/10.1038/s41598-018-30844-5
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