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Stefaan De Wolf

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Publications associées (80)

Characterizing amorphous silicon, silicon nitride, and diffused layers in crystalline silicon solar cells using micro-photoluminescence spectroscopy

Stefaan De Wolf, Johannes Peter Seif

We report and explain the photoluminescence (PL) spectra from crystalline silicon (c-Si) wafers passivated by hydrogenated amorphous silicon (a-Si:H) films under various measurement conditions, utilizing the different absorption coefficients and radiative ...

Elsevier Science Bv2016

Light-induced performance increase of silicon heterojunction solar cells

Christophe Ballif, Antoine Descoeudres, Jacques Levrat, Sylvain Nicolay, Gabriel Christmann, Stefaan De Wolf, Matthieu Despeisse, Eiji Kobayashi

Silicon heterojunction solar cells consist of crystalline silicon (c-Si) wafers coated with doped/intrinsic hydrogenated amorphous silicon (a-Si:H) bilayers for passivating-contact formation. Here, we unambiguously demonstrate that carrier injection either ...

American Institute of Physics2016

Lithium Fluoride Based Electron Contacts for High Efficiency n-Type Crystalline Silicon Solar Cells

Aïcha Hessler-Wyser, Quentin Thomas Jeangros, Mahmut Tosun, Stefaan De Wolf

Low-resistance contact to lightly doped n-type crystalline silicon (c-Si) has long been recognized as technologically challenging due to the pervasive Fermi-level pinning effect. This has hindered the development of certain devices such as n-type c-Si sola ...

Wiley-VCH Verlag Berlin2016

Tuning the Optoelectronic Properties of ZnO:Al by Addition of Silica for Light Trapping in High-Efficiency Crystalline Si Solar Cells

Christophe Ballif, Aïcha Hessler-Wyser, Ali Dabirian, Stefaan De Wolf, Monica Morales Masis, Björn Niesen

Highly transparent electrodes with a well-tuned refractive index are essential for a wide range of optoelectronic devices, such as light emitting diodes and solar cells. Here, it is shown that the transparency of ZnO:Al can be improved and its refractive i ...

Wiley-Blackwell2016

Asymmetric band offsets in silicon heterojunction solar cells: Impact on device performance

Christophe Ballif, Antoine Descoeudres, Stefaan De Wolf, Loris Barraud, Johannes Peter Seif, Ugur Deneb Menda

Amorphous/crystalline silicon interfaces feature considerably larger valence than conduction band offsets. In this article, we analyze the impact of such band offset asymmetry on the performance of silicon heterojunction solar cells. To this end, we use si ...

Amer Inst Physics2016

Strategies for Doped Nanocrystalline Silicon Integration in Silicon Heterojunction Solar Cells

Christophe Ballif, Aïcha Hessler-Wyser, Antoine Descoeudres, Niels Holm, Martial Duchamp, Stefaan De Wolf, Jonas Geissbühler, Johannes Peter Seif, Simon Hänni, Gizem Nogay, Martin Ledinsky

Carrier collection in silicon heterojunction (SHJ) solar cells is usually achieved by doped amorphous silicon layers of a few nanometers, deposited at opposite sides of the crystalline silicon wafer. These layers are often defect-rich, resulting in modest ...

Ieee-Inst Electrical Electronics Engineers Inc2016

Efficient silicon solar cells with dopant-free asymmetric heterocontacts

Christophe Ballif, Stefaan De Wolf, Jonas Geissbühler

A salient characteristic of solar cells is their ability to subject photo-generated electrons and holes to pathways of asymmetrical conductivity-'assisting' them towards their respective contacts. All commercially available crystalline silicon (c-Si) solar ...

Nature Publishing Group2016

Transparent Electrodes in Silicon Heterojunction Solar Cells: Influence on Contact Passivation

Christophe Ballif, Sylvain Nicolay, Stefaan De Wolf, Florent Sahli, Loris Barraud, Johannes Peter Seif, Lorenzo Fanni, Andrea Tomasi, Bertrand Yves Paul Paviet-Salomon, Björn Niesen, Silvia Martin de Nicolas Agut

Charge carrier collection in silicon heterojunction solar cells occurs via intrinsic/doped hydrogenated amorphous silicon layer stacks deposited on the crystalline silicon wafer surfaces. Usually, both the electron and hole collecting stacks are externally ...

Ieee-Inst Electrical Electronics Engineers Inc2016

Parasitic Absorption Reduction in Metal Oxide-Based Transparent Electrodes: Application in Perovskite Solar Cells

Christophe Ballif, Sylvain Nicolay, Ali Dabirian, Stefaan De Wolf, Jérémie Werner, Monica Morales Masis, Björn Niesen

Transition metal oxides (TMOs) are commonly used in a wide spectrum of device applications, thanks to their interesting electronic, photochromic, and electrochromic properties. Their environmental sensitivity, exploited for gas and chemical sensors, is how ...

Amer Chemical Soc2016

High-efficiency crystalline silicon solar cells: status and perspectives

Stefaan De Wolf, Corsin Battaglia

With a global market share of about 90%, crystalline silicon is by far the most important photovoltaic technology today. This article reviews the dynamic field of crystalline silicon photovoltaics from a device-engineering perspective. First, it discusses ...

Royal Society of Chemistry2016

Efficient Monolithic Perovskite/Silicon Tandem Solar Cell with Cell Area >1 cm

Christophe Ballif, Arnaud Walter, Stefaan De Wolf, Luc Fesquet, Jérémie Werner, Johannes Peter Seif, Björn Niesen, Ching-Hsun Weng

Monolithic perovskite/crystalline silicon tandem solar cells hold great promise for further performance improvement of well-established silicon photovoltaics; however, monolithic tandem integration is challenging, evidenced by the modest performances and s ...

Amer Chemical Soc2016

Field-effect passivation on silicon nanowire solar cells (vol 8, pg 673, 2015)

Bénédicte Demaurex, Anna Fontcuberta i Morral, Stefaan De Wolf, Anna Dalmau Mallorquí, Amirreza Kiani

Surface recombination represents a handicap for high-efficiency solar cells. Surface recombination represents a handicap for high-efficiency solar cells. This is especially important for nanowire array solar cells, where the surface-to-volume ratio is grea ...

Tsinghua Univ Press2016

Profilometry of thin films on rough substrates by Raman spectroscopy

Christophe Ballif, Stefaan De Wolf, Matthieu Despeisse, Jonas Geissbühler, Andrea Tomasi, Bertrand Yves Paul Paviet-Salomon, Martin Ledinsky

Thin, light-absorbing films attenuate the Raman signal of underlying substrates. In this article, we exploit this phenomenon to develop a contactless thickness profiling method for thin films deposited on rough substrates. We demonstrate this technique by ...

Nature Research2016

Efficient Near-Infrared-Transparent Perovskite Solar Cells Enabling Direct Comparison of 4-Terminal and Monolithic Perovskite/Silicon Tandem Cells

Christophe Ballif, Sylvain Nicolay, Soo-Jin Moon, Arnaud Walter, Davide Sacchetto, Nicolas Tétreault, Stefaan De Wolf, Matthieu Despeisse, Jérémie Werner, Florent Sahli, Loris Barraud, Bertrand Yves Paul Paviet-Salomon, Björn Niesen, Matthias Wolfgang Bräuninger

Combining market-proven silicon solar cell technology with an efficient wide band gap top cell into a tandem device is an attractive approach to reduce the cost of photovoltaic systems. For this, perovskite solar cells are promising high-efficiency top cel ...

Amer Chemical Soc2016

Probing Photocurrent Nonuniformities in the Subcells of Monolithic Perovskite/Silicon Tandem Solar Cells

Christophe Ballif, Stefaan De Wolf, Jérémie Werner, Florent Sahli, Björn Niesen, Randall Ellingson

Perovskite/silicon tandem solar cells with high power conversion efficiencies have the potential to become a commercially viable photovoltaic option in the near future. However, device design and optimization is challenging because conventional characteriz ...

Amer Chemical Soc2016

Zinc tin oxide as high-temperature stable recombination layer for mesoscopic perovskite/silicon monolithic tandem solar cells

Christophe Ballif, Sylvain Nicolay, Soo-Jin Moon, Arnaud Walter, Davide Sacchetto, Stefaan De Wolf, Xavier Niquille, Jérémie Werner, Monica Morales Masis, Björn Niesen, Philipp Friedrich Hermann Löper, Oscar Esteban Rucavado Leandro

Perovskite/crystalline silicon tandem solar cells have the potential to reach efficiencies beyond those of silicon single-junction record devices. However, the high-temperature process of 500 °C needed for state-of-the-art mesoscopic perovskite cells has, ...

American Institute of Physics2016

Nanocrystalline Silicon Carrier Collectors for Silicon Heterojunction Solar Cells and Impact on Low-Temperature Device Characteristics

Christophe Ballif, Quentin Thomas Jeangros, Stefaan De Wolf, Nicolas Würsch, Franz-Josef Haug, Yannick Samuel Riesen, Johannes Peter Seif, Andrea Tomasi, Gizem Nogay

Silicon heterojunction solar cells typically use stacks of hydrogenated intrinsic/doped amorphous silicon layers as carrier selective contacts. However, the use of these layers may cause parasitic optical absorption losses and moderate fill factor (FF) val ...

Ieee-Inst Electrical Electronics Engineers Inc2016

Organic-inorganic halide perovskite/crystalline silicon four-terminal tandem solar cells

Christophe Ballif, Sylvain Nicolay, Jun Ho Yum, Soo-Jin Moon, Stefaan De Wolf, Julien Claude Bailat, Björn Niesen, Martin Ledinsky

Tandem solar cells constructed from a crystalline silicon (c-Si) bottom cell and a low-cost top cell offer a promising way to ensure long-term price reductions of photovoltaic modules. We present a four-terminal tandem solar cell consisting of a methyl amm ...

Royal Society of Chemistry2015

Effect of the thin-film limit on the measurable optical properties of graphene

Christophe Ballif, Sylvain Nicolay, Stefaan De Wolf, Jakub Holovsky

The fundamental sheet conductance of graphene can be directly related to the product of its absorption coefficient, thickness and refractive index. The same can be done for graphene's fundamental opacity if the so-called thin-film limit is considered. Here ...

Nature Publishing Group2015

Practical silicon deposition rules derived from silane monitoring during plasma-enhanced chemical vapor deposition

Christophe Ballif, Bénédicte Demaurex, Stefaan De Wolf

We clarify the difference between the SiH4 consumption efficiency eta and the SiH4 depletion fraction D, as measured in the pumping line and the actual reactor of an industrial plasma-enhanced chemical vapor deposition system. In the absence of significant ...

American Institute of Physics2015

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