On the geometry of plasmonic reflection grating back contacts for light trapping in prototype amorphous silicon thin-film solar cells

Michael Smeets; Vladimir Smirnov; Matthias Meier; Karsten Bittkau; Reinhard Carius; Uwe Rau; Ulrich W. Paetzold

doi:10.1117/1.JPE.5.057004

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20 November 2014 On the geometry of plasmonic reflection grating back contacts for light trapping in prototype amorphous silicon thin-film solar cells

Michael Smeets, Vladimir Smirnov, Matthias Meier, Karsten Bittkau, Reinhard Carius, Uwe Rau, Ulrich W. Paetzold

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J. of Photonics for Energy, 5(1), 057004 (2014). https://doi.org/10.1117/1.JPE.5.057004

Abstract

We experimentally investigate the light-trapping effect of plasmonic reflection grating back contacts in prototype hydrogenated amorphous silicon thin-film solar cells in substrate configuration. These back contacts consist of periodically arranged Ag nanostructures on flat Ag reflectors. We vary the period, unit cell, and width of the nanostructures to identify design strategies for optimized light trapping. First, a general correlation between the reduction of the period of the nanostructures down to 550 nm and an increase of the absorptance, as well as external quantum efficiency is found for various unit cells formed by nanostructures. Second, increasing the width of the nanostructures from 200 to 350 nm, an enhanced light-trapping effect of the thin-film solar cells is found independent of the period. As a result, we identify a design for improved light trapping for the given solar cell parameters within the considered variations. It consists of thin-film solar cells applying a combination of a period of 600 nm and a structure width of 350 nm. The implementation of back contacts with this configuration yields enhanced power conversion efficiency as compared to reference solar cells processed on conventionally used randomly textured substrates. In detail, the enhancement of the short-circuit current density from initially 14.7 to initially 15.6 mA/cm² improves the power conversion efficiency from 9.1 to 9.3%.

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Michael Smeets, Vladimir Smirnov, Matthias Meier, Karsten Bittkau, Reinhard Carius, Uwe Rau, and Ulrich W. Paetzold "On the geometry of plasmonic reflection grating back contacts for light trapping in prototype amorphous silicon thin-film solar cells," Journal of Photonics for Energy 5(1), 057004 (20 November 2014). https://doi.org/10.1117/1.JPE.5.057004

Published: 20 November 2014

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