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Biomimetic nanostructured surfaces for antireflection in photovoltaics

Biomimetic nanostructured surfaces for antireflection in photovoltaics
Biomimetic nanostructured surfaces for antireflection in photovoltaics
A key consideration in the design of any solar cell is the reduction of reflectance from the top surface. Traditional thin film antireflection schemes are being challenged by new techniques that involve texturing on the subwavelength scale to form ‘moth-eye’ arrays, so called because they are inspired by Nature’s answer to unwanted reflections, the arrays of pillars found on the eyes and wings of some species of moth. In this work, a new method is presented for the optimization of thin film coatings that accounts for the angular and spectral variations in incident solar radiation from sunrise to sunset. This approach is then extended to silicon moth-eye arrays to assess how effectively these surfaces can provide antireflection for silicon solar cells over a full day. The reflectance spectra of moth-eye surfaces are found to depend on the period of the arrays and the height and shape of the pillars, and consequently these parameters can be optimized for the solar spectrum. Simulations predict that replacing an optimized double layer thin film coating with a moth-eye array could increase the full day cell performance by 2% for a laboratory cell and 3% for an encapsulated cell. Compared to a perfectly transmitting interface, this corresponds to losses in short circuit current of only 5.3% and 0.6% for a laboratory and an encapsulated cell, respectively. Furthermore, fabrication of silicon moth-eye arrays by electron beam lithography and dry etching leads to predicted percentage losses at peak irradiance, compared to an ideal antireflective surface, of only 1%. The potentially more scalable technique of nanoimprint lithography is also used to fabricate antireflective moth-eye arrays in silicon, over areas as large as 1 cm2, demonstrating great potential for stealth and antiglare applications in addition to photovoltaics.
Boden, Stuart Andrew
83976b65-e90f-42d1-9a01-fe9cfc571bf8
Boden, Stuart Andrew
83976b65-e90f-42d1-9a01-fe9cfc571bf8
Bagnall, Darren
5d84abc8-77e5-43f7-97cb-e28533f25ef1

Boden, Stuart Andrew (2009) Biomimetic nanostructured surfaces for antireflection in photovoltaics. University of Southampton, School of Electronics and Computer Science, Doctoral Thesis, 266pp.

Record type: Thesis (Doctoral)

Abstract

A key consideration in the design of any solar cell is the reduction of reflectance from the top surface. Traditional thin film antireflection schemes are being challenged by new techniques that involve texturing on the subwavelength scale to form ‘moth-eye’ arrays, so called because they are inspired by Nature’s answer to unwanted reflections, the arrays of pillars found on the eyes and wings of some species of moth. In this work, a new method is presented for the optimization of thin film coatings that accounts for the angular and spectral variations in incident solar radiation from sunrise to sunset. This approach is then extended to silicon moth-eye arrays to assess how effectively these surfaces can provide antireflection for silicon solar cells over a full day. The reflectance spectra of moth-eye surfaces are found to depend on the period of the arrays and the height and shape of the pillars, and consequently these parameters can be optimized for the solar spectrum. Simulations predict that replacing an optimized double layer thin film coating with a moth-eye array could increase the full day cell performance by 2% for a laboratory cell and 3% for an encapsulated cell. Compared to a perfectly transmitting interface, this corresponds to losses in short circuit current of only 5.3% and 0.6% for a laboratory and an encapsulated cell, respectively. Furthermore, fabrication of silicon moth-eye arrays by electron beam lithography and dry etching leads to predicted percentage losses at peak irradiance, compared to an ideal antireflective surface, of only 1%. The potentially more scalable technique of nanoimprint lithography is also used to fabricate antireflective moth-eye arrays in silicon, over areas as large as 1 cm2, demonstrating great potential for stealth and antiglare applications in addition to photovoltaics.

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Published date: May 2009
Organisations: University of Southampton

Identifiers

Local EPrints ID: 66278
URI: https://eprints.soton.ac.uk/id/eprint/66278
PURE UUID: 6f1addc9-4570-46a4-85ed-988cbb828cb1
ORCID for Stuart Andrew Boden: ORCID iD orcid.org/0000-0002-4232-1828

Catalogue record

Date deposited: 27 May 2009
Last modified: 06 Jun 2018 12:43

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Contributors

Author: Stuart Andrew Boden ORCID iD
Thesis advisor: Darren Bagnall

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