Tuning light scattering by periodic metal nanoparticle arrays for solar cell applications

Research output: Chapter in Book/Report/Conference proceedingConference proceeding contribution

Abstract

The drive to reduce the thickness of solar cells is putting ever greater demands on light-trapping techniques. Techniques are required to improve absorption of light within the semiconductor, while not adversely affecting the electrical properties of the device. Conventional diffraction gratings can scatter visible and near-infrared photons into large angles, which get trapped in the silicon layer by total internal reflection. However, diffraction gratings typically have large feature sizes and so increase the overall surface area of a solar cell compared to the planar case. A periodic arrangement of metal nanoparticles acts as a diffraction grating, but an over-coated semiconductor will have a similar surface area to a planar layer due a combination of a low particle height and low surface coverage.

Random arrays of identical metal nanoparticles feature Lorentzian scattering peaks that can be tuned by modifying the size and shape of the particle. Periodic arrays have much more complicated scattering peaks, due to the enhancement and suppression of scattering at different wavelengths caused by the constructive and destructive interference between each nanoparticle. In effect the scattering spectrum of the individual nanoparticle is modified by the diffractive orders of the array, and so both parameters must be optimized together.

We have studied periodic arrays of metal nanoparticles fabricated using electron-beam lithography, and characterised their reflectance properties. The optical properties of the fabricated arrays were found to be in good agreement with finite-difference time-domain (FDTD) simulations. Au and Al nanoparticles are found to have a strong scattering effect and Al nanoparticles are also shown to exhibit an anti-reflection effect in combination with scattering. This work is focused on verifying that FDTD simulations can accurately model metal nanoparticle arrays and then extending the simulations to determine the previously unknown transmittance characteristics of metal nanoparticle arrays on silicon.

Original languageEnglish
Title of host publicationPhotonic and plasmonic materials for enhanced photovoltaic performance
Place of PublicationNew York
PublisherCambridge University Press
Pages44-49
Number of pages6
ISBN (Print)9781627482110
Publication statusPublished - 2011
Externally publishedYes
Event2011 MRS Fall Meeting - Boston, United States
Duration: 28 Nov 20112 Dec 2011

Publication series

NameMaterials Research Society Symposium Proceedings
PublisherCambridge University Press
Volume1391

Other

Other2011 MRS Fall Meeting
CountryUnited States
CityBoston
Period28/11/112/12/11

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