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Stefaan De Wolf

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Related publications (78)

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Simple processing of back-contacted silicon heterojunction solar cells using selective-area crystalline growth

Christophe Ballif, Antoine Descoeudres, Sylvain Nicolay, Quentin Thomas Jeangros, Gabriel Christmann, Stefaan De Wolf, Matthieu Despeisse, Loris Barraud, Johannes Peter Seif, Andrea Tomasi, Bertrand Yves Paul Paviet-Salomon, Jan Haschke

For crystalline-silicon solar cells, voltages close to the theoretical limit are nowadays readily achievable when using passivating contacts. Conversely, maximal current generation requires the integration of the electron and hole contacts at the back of t ...

Nature Publishing Group2017

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

Photocurrent Spectroscopy of Perovskite Layers and Solar Cells: A Sensitive Probe of Material Degradation

Christophe Ballif, Stefaan De Wolf, Jérémie Werner, Jakub Holovsky, Björn Niesen, Martin Ledinsky, Philipp Friedrich Hermann Löper

Optical absorptance spectroscopy of polycrystalline CH3NH3PbI3 films usually indicates the presence of a PbI2 phase, either as a preparation residue or due to film degradation, but gives no insight on how this may affect electrical properties. Here, we app ...

Amer Chemical Soc2017

Amorphous Silicon/Crystalline Silicon Heterojunction Solar Cells

Christophe Ballif, Antoine Descoeudres, Stefaan De Wolf

Silicon heterojunction solar cells are crystalline silicon-based devices in which thin amorphous silicon layers deposited on the wafer surfaces serve as passivated, carrier-selective contacts. The success of this technology is attributable to the ability o ...

Elsevier Academic Press Inc2014

Field Performance versus Standard Test Condition Efficiency of Tandem Solar Cells and the Singular Case of Perovskites/Silicon Devices

Christophe Ballif, Stefaan De Wolf, Björn Niesen, Olivier Denis Dupré

Multijunction cells may offer a cost-effective route to boost the efficiency of industrial photovoltaics. For any technology to be deployed in the field, its performance under actual operating conditions is extremely important. In this perspective, we eval ...

2018

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

Interdigitated back contact silicon heterojunction solar cells featuring an interband tunnel junction enabling simplified processing

Christophe Ballif, Antoine Descoeudres, Benjamin Strahm, Antonin Faes, Sylvain Nicolay, Quentin Thomas Jeangros, Gabriel Christmann, Stefaan De Wolf, Matthieu Despeisse, Loris Barraud, Jonas Geissbühler, Johannes Peter Seif, Andrea Tomasi, Bertrand Yves Paul Paviet-Salomon

This paper reports on the development of an innovative back-contacted crystalline silicon solar cell with passivating contacts featuring an interband tunnel junction at its electron-collecting contacts. In this novel architecture, named "tunnel-IBC", both ...

2018

Silicon Heterojunction Solar Cells With Copper-Plated Grid Electrodes: Status and Comparison With Silver Thick-Film Techniques

Christophe Ballif, Antoine Descoeudres, Antonin Faes, Quentin Thomas Jeangros, Stefaan De Wolf, Matthieu Despeisse, Loris Barraud, Jonas Geissbühler, Andrea Tomasi

Copper electroplating is investigated and compared with common silver printing techniques for the front metallization of silicon heterojunction solar cells. We achieve smaller feature sizes by electroplating, significantly reducing optical shadowing losses ...

Ieee-Inst Electrical Electronics Engineers Inc2014

Raman Spectroscopy of Organic-Inorganic Halide Perovskites

Christophe Ballif, Jun Ho Yum, Soo-Jin Moon, Stefaan De Wolf, Jakub Holovsky, Björn Niesen, Martin Ledinsky

Micro-Raman spectroscopy provides laterally resolved microstructural information for a broad range of materials. In this Letter, we apply this technique to tri-iodide (CH3NH3PbI3), tribromide (CH3NH3PbBr3), and mixed iodide-bromide (CH3NH3PbI3-xBrx) organi ...

Amer Chemical Soc2015

Amorphous/crystalline silicon interface defects induced by hydrogen plasma treatments

Christophe Ballif, Bénédicte Demaurex, Duncan Thomas Lindsay Alexander, Stefaan De Wolf, Loris Barraud, Jonas Geissbühler, Johannes Peter Seif

Excellent amorphous/crystalline silicon interface passivation is of extreme importance for high-efficiency silicon heterojunction solar cells. This can be obtained by inserting hydrogen-plasma treatments during deposition of the amorphous silicon passivati ...

American Institute of Physics2013

CH3NH3PbI3 perovskite/silicon tandem solar cells: characterization based optical simulations

Christophe Ballif, Stefaan De Wolf, Björn Niesen

In this study we analyze and discuss the optical properties of various tandem architectures: mechanically stacked (four-terminal) and monolithically integrated (two-terminal) tandem devices, consisting of a methyl ammonium lead triiodide (CH3NH3PbI3) perov ...

Optical Society of America2015

Textured silicon heterojunction solar cells with over 700mV open-circuit voltage studied by transmission electron microscopy

Christophe Ballif, Aïcha Hessler-Wyser, Christian Monachon, Stefaan De Wolf, Luc Fesquet

In this article, we report on the use of transmission electron microscopy (TEM) for the fabrication of high-performance textured amorphous/crystalline silicon (a-Si:H/c-Si) heterojunction (HJ) solar cells. Whereas classical thin-film characterization techn ...

2008

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

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

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

Toward Annealing-Stable Molybdenum-Oxide-Based Hole-Selective Contacts For Silicon Photovoltaics

Christophe Ballif, Stefaan De Wolf, Mathieu Gérard Boccard, Jérémie Werner, Jonas Geissbühler, Monica Morales Masis, Philipp Friedrich Hermann Löper, Oscar Esteban Rucavado Leandro, Stephanie Essig, Julie Amandine Dreon

Molybdenum oxide (MoOX) combines a high work function with broadband optical transparency. Sandwiched between a hydrogenated intrinsic amorphous silicon passivation layer and a transparent conductive oxide, this material allows a highly efficient hole‐sele ...

2018

Imaging the Spatial Evolution of Degradation in Perovskite/Si Tandem Solar Cells After Exposure to Humid Air

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

Monolithically integrated two-terminal perovskite/Si tandem solar cells promise to achieve high power conversion efficiency. However, there is a concern that the stability of the perovskite top cell will limit the long-term performance of tandem devices. T ...

Ieee-Inst Electrical Electronics Engineers Inc2017

Photovoltaics at multi-terawatt scale: Waiting is not an option

Stefaan De Wolf, Sophia Haussener

A major renewable-energy milestone occurred in 2022: Photovoltaics (PV) exceeded a global installed capacity of 1 TWdc. But despite considerable growth and cost reduction over time, PV is still a small part of global electricity generation (4 to 5% for 202 ...

American Association for the Advancement of Science2023

High-efficiency Silicon Heterojunction Solar Cells: A Review

Christophe Ballif, Antoine Descoeudres, Stefaan De Wolf

De Gruyter, De Gruyter2012

Towards a better understanding of silicon heterojunction solar cells

Christophe Ballif, Stefaan De Wolf, Luc Fesquet

2009