Highly transparent front electrodes with metal fingers for p-i-n thin-film silicon solar cells
Ecole Polytechnique Fédérale de Lausanne (EPFL), Institute of
Microengineering (IMT), Photovoltaics and Thin-Film Electronics
Laboratory, Rue de la Maladière
2 IEK5-Photovoltaik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
a e-mail: firstname.lastname@example.org
Received in final form: 12 January 2015
Accepted: 15 January 2015
Published online: 9 March 2015
The optical and electrical properties of transparent conductive oxides (TCOs), traditionally used in thin-film silicon (TF-Si) solar cells as front-electrode materials, are interlinked, such that an increase in TCO transparency is generally achieved at the cost of reduced lateral conductance. Combining a highly transparent TCO front electrode of moderate conductance with metal fingers to support charge collection is a well-established technique in wafer-based technologies or for TF-Si solar cells in the substrate (n-i-p) configuration. Here, we extend this concept to TF-Si solar cells in the superstrate (p-i-n) configuration. The metal fingers are used in conjunction with a millimeter-scale textured foil, attached to the glass superstrate, which provides an antireflective and retroreflective effect; the latter effect mitigates the shadowing losses induced by the metal fingers. As a result, a substantial increase in power conversion efficiency, from 8.7% to 9.1%, is achieved for 1-μm-thick microcrystalline silicon solar cells deposited on a highly transparent thermally treated aluminum-doped zinc oxide layer combined with silver fingers, compared to cells deposited on a state-of-the-art zinc oxide layer.
© Moulin et al., published by EDP Sciences, 2015
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