2015
ACL
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P.Yu, J.P.Blondeau, C.Andreazza, E.Ntsoenzok, J.Roussel, P.Dutheil, A.L.Thomann, A.Caillard, E.Mustapha, J.Meot, 'Influence of Gold nanoparticles (Au NPs) for performance improvement of a-Si:H photovoltaic cells', Plasmonics 10 691-701 (2015) doi:10.1007/s11468-014-9855-4
The efficiency of thin-film solar cells using a-Si:H is limited by the decrease in a-Si:H
layer optical path length and its poor light absorption at red and NIR wavelengths. Metal NPs
such as Au have been shown to increase the absorption in the active material and the cell
performances, by exhibiting localized surface plasmon (LSP) resonances. Our work’s goal is to
understand NPs influence in such cells, and to perform an optimal structure by increasing the
amount of light absorbed within the cell using NPs scattering. Modeling based on Mie theory is
first carried out using bulk Palik data for Au spheres with various diameters and refractive
medium indexes. Using modeling results, Au layers were deposited on glass and SnO2 substrates
either by thermal evaporation in vacuum or sputtering, followed by thermal annealing (200 ~
500°C) in order to promote the NPs growth. MEB pictures show quasi-spherical Au NPs shape
with an average size around 100nm depending of the deposited layer and the annealing
temperature and time. This diameter range switches extinction of NPs in scattering regime.
Annealing temperature strongly affects the NPs morphology. Surface coverage decreases and
sphericity appears to increase with T. UV-Visible spectroscopy displays distinct LSP resonances
around 672nm after annealing with a red shift while T increases. Based on these results, the thin
films a-Si:H solar cells with Au NPs are realized and studied. Confirmed with the modeling
results and the experimental values, the configuration in NIP junction with the Au NPs in back
contact can optimize the photovoltaic properties, by the backscattering of incident light.
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