Home

Person

Stefaan De Wolf

This person is no longer with EPFL

About
Privacy
Disclaimer

Graph Chatbot

Related publications (80)

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

Christophe Ballif, Antoine Descoeudres, Nicolas Badel, 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

Amorphous silicon enhanced metal-insulator-semiconductor contacts for silicon solar cells

Aïcha Hessler-Wyser, Bénédicte Demaurex, Stefaan De Wolf

Carrier recombination at the metal-semiconductor contacts has become a significant obstacle to the further advancement of high-efficiency diffused-junction silicon solar cells. This paper provides the proof-of-concept of a procedure to reduce contact recom ...

American Institute of Physics2014

Amorphous silicon passivated contacts for diffused junction silicon solar cells

Aïcha Hessler-Wyser, Bénédicte Demaurex, Stefaan De Wolf

Carrier recombination at the metal contacts is a major obstacle in the development of high-performance crystalline silicon homojunction solar cells. To address this issue, we insert thin intrinsic hydrogenated amorphous silicon [a-Si: H(i)] passivating fil ...

American Institute of Physics2014

Amorphous silicon oxide window layers for high-efficiency silicon heterojunction solar cells

Christophe Ballif, Antoine Descoeudres, Stefaan De Wolf, Johannes Peter Seif

In amorphous/crystalline silicon heterojunction solar cells, optical losses can be mitigated by replacing the amorphous silicon films by wider bandgap amorphous silicon oxide layers. In this article, we use stacks of intrinsic amorphous silicon and amorpho ...

American Institute of Physics2014

Back-Contacted Silicon Heterojunction Solar Cells With Efficiency >21%

Christophe Ballif, Antoine Descoeudres, Stefaan De Wolf, Jonas Geissbühler, Andrea Tomasi, Bertrand Yves Paul Paviet-Salomon, Silvia Martin de Nicolas Agut

We report on the fabrication of back-contacted silicon heterojunction solar cells with conversion efficiencies above 21%. Our process technology relies solely on simple and size-scalable patterning methods, with no high-temperature steps. Using in situ sha ...

Ieee-Inst Electrical Electronics Engineers Inc2014

Record Infrared Internal Quantum Efficiency in Silicon Heterojunction Solar Cells With Dielectric/Metal Rear Reflectors

Christophe Ballif, Antoine Descoeudres, Stefaan De Wolf

Inserting a dielectric between the absorber and rear metal electrode of a solar cell increases rear internal reflectance by both limiting the transmission cone and suppressing the plasmonic absorption of light arriving outside of the cone. We fabricate rea ...

Ieee-Inst Electrical Electronics Engineers Inc2013

Improving metal reflectors by suppressing surface plasmon polaritons: a priori calculation of the internal reflectance of a solar cell

Christophe Ballif, Stefaan De Wolf

Imperfect internal reflectance of near-bandgap light reduces the performance of all solar cells, and becomes increasingly detrimental as absorbers become thinner. We consider light incident on the silicon/dielectric/metal structure at the back of rear-pass ...

Nature Publishing Group2013

Analysis of lateral transport through the inversion layer in amorphous silicon/crystalline silicon heterojunction solar cells

Christophe Ballif, Stefaan De Wolf

In amorphous/crystalline silicon heterojunction solar cells, an inversion layer is present at the front interface. By combining numerical simulations and experiments, we examine the contribution of the inversion layer to lateral transport and assess whethe ...

American Institute of Physics2013

Hydrogen-doped indium oxide/indium tin oxide bilayers for high-efficiency silicon heterojunction solar cells

Christophe Ballif, Antoine Descoeudres, Nicolas Badel, Stefaan De Wolf, Corsin Battaglia, Loris Barraud

The front transparent conductive oxide layer is a source of significant optical and electrical losses in silicon heterojunction solar cells because of the trade-off between free-carrier absorption and sheet resistance. We demonstrate that hydrogen-doped in ...

Elsevier2013

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

A-Si:H/c-Si heterojunctions: a future mainstream technology for high-efficiency crystalline silicon solar cells ?

Christophe Ballif, Antoine Descoeudres, Stefaan De Wolf, Loris Barraud

In this contribution, we shortly review the main features of amorphous/crystalline silicon heterojunction (SHJ) solar cells, including interface defects and requirements for high quality interfaces. We show how a process flow with a limited number of proce ...

Ieee2012

Kinetics of a-Si:H bulk defect and a-Si:H/c-Si interface-state reduction

Christophe Ballif, Stefaan De Wolf

Low-temperature annealing of hydrogenated amorphous silicon (a-Si:H) is investigated. An identical energy barrier is found for the reduction of deep defects in the bulk of a-Si:H films and at the interface such layers form with crystalline Si (c-Si) surfac ...

2012

High-efficiency Silicon Heterojunction Solar Cells: A Review

Christophe Ballif, Antoine Descoeudres, Stefaan De Wolf

De Gruyter, De Gruyter2012

Improved amorphous/crystalline silicon interface passivation by hydrogen plasma treatment

Christophe Ballif, Antoine Descoeudres, Benjamin Strahm, Bénédicte Demaurex, Stefaan De Wolf, Loris Barraud, Jakub Holovsky, Johannes Peter Seif

Silicon heterojunction solar cells have high open-circuit voltages thanks to excellent passivation of the wafer surfaces by thin intrinsic amorphous silicon (a-Si:H) layers deposited by plasma-enhanced chemical vapor deposition. We show a dramatic improvem ...

2011

Properties of interfaces in amorphous/crystalline silicon heterojunctions

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

To study recombination at the amorphous/crystalline Si (a- Si:H/c-Si) heterointerface, the amphoteric nature of silicon (Si) dangling bonds is taken into account. Modeling interface recombination measured on various test structures provides insight into th ...

Wiley2010

Modification of textured silicon wafer surface morphology for fabrication of heterojunction solar cell with open circuit voltage over 700mV

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

Crystalline silicon wafer (c-Si) can be extremely well passivated by plasma enhanced chemical vapor deposited (PECVD) amorphous silicon (a-Si:H) films. As a result, on flat substrates, solar cells with very high open circuit voltage are readily obtained. O ...

2010

Towards a better understanding of silicon heterojunction solar cells

Christophe Ballif, Stefaan De Wolf, Luc Fesquet

2009

Impact of annealing on passivation properties of a-Si:H / c-Si heterostructures

Stefaan De Wolf

The a-Si:H / c-Si heterostructure, is an attractive solution to avoid the presence of highly recombinative metal contacts at the surfaces of c-Si based solar cells. To assure good interface passivation, insertion of a sandwiched thin device-grade intrinsic ...

2009

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

Understanding of passivation mechanism in heterojunction c-Si solar cells

Stefaan De Wolf

Intrinsic hydrogenated amorphous silicon (a-Si:H) films can yield in outstanding electronic surface passivation of crystalline silicon (c-Si) wafers as utilized in the HIT (heterojunction with intrinsic thin layer) solar cells. We have studied the correlat ...

Materials Research Society2008

Page 4 of 4