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Stefaan De Wolf

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Publications associées (80)

Complex Refractive Index Spectra of CH3NH3PbI3 Perovskite Thin Films Determined by Spectroscopic Ellipsometry and Spectrophotometry

Christophe Ballif, Jun Ho Yum, Soo-Jin Moon, Stefaan De Wolf, Michael Elias Stückelberger, Jérémie Werner, Björn Niesen

The complex refractive index (dielectric function) of planar CH3NH3PbI3 thin films at room temperature is investigated by variable angle spectroscopic ellipsometry and spectrophotometry. Knowledge of the complex refractive index is essential for designing ...

Amer Chemical Soc2015

Attenuated total reflectance Fourier-transform infrared spectroscopic investigation of silicon heterojunction solar cells

Christophe Ballif, Stefaan De Wolf, Jakub Holovsky

Silicon heterojunction solar cells critically depend on the detailed properties of their amorphous/crystalline silicon interfaces. We report here on the use of attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy to gain precise ...

American Institute of Physics2015

Low-Temperature High-Mobility Amorphous IZO for Silicon Heterojunction Solar Cells

Christophe Ballif, Stefaan De Wolf, Jakub Holovsky, Monica Morales Masis

Parasitic absorption in the transparent conductive oxide (TCO) front electrode is one of the limitations of silicon heterojunction (SHJ) solar cells efficiency. To avoid such absorption while retaining high conductivity, TCOs with high electron mobility ar ...

Ieee-Inst Electrical Electronics Engineers Inc2015

Amorphous/Crystalline Silicon Interface Passivation: Ambient-Temperature Dependence and Implications for Solar Cell Performance

Christophe Ballif, Bénédicte Demaurex, Stefaan De Wolf, Johannes Peter Seif

Silicon heterojunction (SHJ) solar cells feature amorphous silicon passivation films, which enable very high voltages. We report how such passivation increases with operating temperature for amorphous silicon stacks involving doped layers and decreases for ...

Ieee-Inst Electrical Electronics Engineers Inc2015

Manufacturing 100-mu m-thick silicon solar cells with efficiencies greater than 20% in a pilot production line

Christophe Ballif, Antoine Descoeudres, Stefaan De Wolf

Reducing wafer thickness while increasing power conversion efficiency is the most effective way to reduce cost per Watt of a silicon photovoltaic module. Within the European project 20 percent efficiency on less than 100-mu m-thick, industrially feasible c ...

Wiley-VCH Verlag2015

Field-effect passivation on silicon nanowire solar cells

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

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 greatly enhanced. Here, the effect of different passivation materials on the effe ...

Tsinghua Univ Press2015

Back-Contacted Silicon Heterojunction Solar Cells: Optical-Loss Analysis and Mitigation

Christophe Ballif, Antoine Descoeudres, Sylvain Nicolay, Stefaan De Wolf, Matthieu Despeisse, Loris Barraud, Andrea Tomasi, Bertrand Yves Paul Paviet-Salomon

We analyze the optical losses that occur in interdigitated back-contacted amorphous/crystalline silicon heterojunction solar cells. We show that in our devices, the main loss mechanisms are similar to those of two-side contacted heterojunction solar cells. ...

Ieee-Inst Electrical Electronics Engineers Inc2015

22.5% efficient silicon heterojunction solar cell with molybdenum oxide hole collector

Christophe Ballif, Aïcha Hessler-Wyser, Sylvain Nicolay, Stefaan De Wolf, Matthieu Despeisse, Jérémie Werner, Loris Barraud, Andrea Tomasi, Björn Niesen

Substituting the doped amorphous silicon films at the front of silicon heterojunction solar cells with wide-bandgap transition metal oxides can mitigate parasitic light absorption losses. This was recently proven by replacing p-type amorphous silicon with ...

American Institute of Physics2015

Environmental stability of high-mobility indium-oxide based transparent electrodes

Christophe Ballif, Ali Dabirian, Stefaan De Wolf, Monica Morales Masis, Thanaporn Tohsophon

Large-scale deployment of a wide range of optoelectronic devices, including solar cells, critically depends on the long-term stability of their front electrodes. Here, we investigate the performance of Sn-doped In2O3 (ITO), H-doped In2O3 (IO:H), and Zn-dop ...

Amer Inst Physics2015

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

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

Sputtered rear electrode with broadband transparency for perovskite solar cells

Christophe Ballif, Guy Joseph Günter Dubuis, Sylvain Nicolay, Soo-Jin Moon, Arnaud Walter, Stefaan De Wolf, Jérémie Werner, Monica Morales Masis, Björn Niesen, Philipp Friedrich Hermann Löper

Due to their high efficiencies combined with simple and cost-effective device fabrication, perovskite solar cells are promising candidates as top cells in tandem devices. For this application, the perovskite solar cell must be highly transparent at near-in ...

Elsevier2015

Parasitic absorption in the rear reflector of a silicon solar cell: Simulation and measurement of the sub-bandgap reflectance for common dielectric/metal reflectors

Christophe Ballif, Stefaan De Wolf

The rear side of a silicon solar cell is often designed to minimize surface recombination, series resistance, and cost, but not necessarily parasitic absorption. We present a comprehensive study of parasitic absorption in the metal layer of solar cells wit ...

Elsevier Science Bv2014

Silicon heterojunction solar cell with passivated hole selective MoOx contact

Christophe Ballif, Stefaan De Wolf, Corsin Battaglia

We explore substoichiometric molybdenum trioxide (MoOx, x < 3) as a dopant-free, hole-selective contact for silicon solar cells. Using an intrinsic hydrogenated amorphous silicon passivation layer between the oxide and the silicon absorber, we demonstrate ...

American Institute of Physics2014

Is light-induced degradation of a-Si:H/c-Si interfaces reversible?

Christophe Ballif, Bénédicte Demaurex, Stefaan De Wolf, El Mahdi El Mhamdi, Jakub Holovsky

Thin hydrogenated amorphous silicon (a-Si:H) films deposited on crystalline silicon (c-Si) surfaces are sensitive probes for the bulk electronic properties of a-Si:H. Here, we use such samples during repeated low-temperature annealing and visible-light soa ...

AIP American Institute of Physics2014

Scanning Laser-Beam-Induced Current Measurements of Lateral Transport Near-Junction Defects in Silicon Heterojunction Solar Cells

Christophe Ballif, Antoine Descoeudres, Stefaan De Wolf

We report the results of scanning laser-beam-induced current (LBIC) measurements on silicon heterojunction solar cells that indicate the length scale over which photogenerated carriers are sensitive to local defects at the amorphous silicon/crystalline sil ...

Ieee-Inst Electrical Electronics Engineers Inc2014

Low-temperature plasma-deposited silicon epitaxial films: Growth and properties

Christophe Ballif, Bénédicte Demaurex, Quentin Thomas Jeangros, Duncan Thomas Lindsay Alexander, Stefaan De Wolf, Johannes Peter Seif

Low-temperature (

American Institute of Physics2014

Organic-Inorganic Halide Perovskites: Perspectives for Silicon-Based Tandem Solar Cells

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

We investigate the efficiency potential of organic-inorganic halide perovskite/crystalline silicon tandem solar cells, a new class of photovoltaic devices targeting long-term cost reductions by ultrahigh conversion efficiencies. Methyl ammonium lead triiod ...

Ieee-Inst Electrical Electronics Engineers Inc2014

Organometallic Halide Perovskites: Sharp Optical Absorption Edge and Its Relation to Photovoltaic Performance

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

Solar cells based on organometallic halide perovskite absorber layers are emerging as a high-performance photovoltaic technology. Using highly sensitive photothermal deflection and photocurrent spectroscopy, we measure the absorption spectrum of CH3NH3PbI3 ...

Amer Chemical Soc2014

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

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