The role of front and back electrodes in parasitic absorption in thin-film solar cells
École Polytechnique Fédérale de Lausanne (EPFL), Institute of
Microengineering (IMT), Photovoltaics and Thin Film Electronics Laboratory,
Rue de la Maladière 71b, CP
Received: 9 March 2014
Received in final form: 17 April 2014
Accepted: 17 April 2014
Published online: 16 July 2014
When it comes to parasitic absorption in thin-film silicon solar cells, most studies focus on one electrode only, most of the time the substrate (in n-i-p configuration) or superstrate (in p-i-n configuration). We investigate here simultaneously the influence of the absorption in both front and back electrodes on the current density of tandem micromorph solar cells in p-i-n configuration. We compare four possible combinations of front and back electrodes with two different doping levels, but identical sheet resistance and identical light-scattering properties. In the infrared part of the spectrum, parasitic absorption in the front or back electrode is shown to have a similar effect on the current generation in the cell, which is confirmed by modeling. By combining highly transparent front and back ZnO electrodes and high-quality silicon layers, a micromorph device with a stabilized efficiency of 11.75% is obtained.
© Boccard et al., published by EDP Sciences, 2014
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