Publications de Jacques Levrat

Stress tolerance of lightweight glass-free PV modules for vehicle integration

Christophe Ballif, Aïcha Hessler-Wyser, Antonin Faes, Jacques Levrat, Matthieu Despeisse, Gianluca Cattaneo, Fahradin Mujovi, Umang Bhupatrai Desai

Electric vehicles (EVs) currently dominate the sales in the automotive market. A big leap in this market can be made by developing a photovoltaic product that can be integrated to an EV, as it can boost the driving range of the EV while reducing the chargi ...

Edp Sciences S A2024

Quantifying and modeling the impact of interconnection failures on the electrical performance of crystalline silicon photovoltaic modules

Christophe Ballif, Fanny Sculati-Meillaud, Antonin Faes, Jacques Levrat, Matthieu Despeisse, Eleonora Annigoni, Alessandro Francesco Aldo Virtuani

Failures in the metallic interconnections are among the main degradation modes for photovoltaic modules. Fatigue accumulation due to thermomechanical stresses can result in deterioration of the solder joints or in broken ribbons. In this paper, we first qu ...

2019

Low-Temperature Screen-Printed Metallization for the Scale-Up of Two-Terminal Perovskite-Silicon Tandems

Christophe Ballif, Nicolas Badel, Antonin Faes, Jacques Levrat, Laura Ding, Sylvain Nicolay, Gabriel Christmann, Soo-Jin Moon, Arnaud Walter, Adriana Paracchino, Matthieu Despeisse, Bertrand Yves Paul Paviet-Salomon

Tandem photovoltaic devices based on perovskite and crystalline silicon (PK/c-Si) absorbers have the potential to push commercial silicon single junction devices beyond their current efficiency limit. However, their scale-up to industrially relevant sizes ...

AMER CHEMICAL SOC2019

Field test and electrode optimization of electrodynamic cleaning systems for solar panels

Christophe Ballif, Aïcha Hessler-Wyser, Nicolas Badel, Antonin Faes, Jacques Levrat, Nicolas Würsch, Matthieu Despeisse

Soiling is the major cause of power loss of photovoltaics (PV) and concentrated solar power (CSP) in desert areas. Electrodynamic cleaning system (EDS) is an automatic and water-free integrated cleaning system for mirrors or solar panels, which uses pulsed ...

WILEY2019

Reassessment of cell to module gains and losses: Accounting for the current boost specific to cells located on the edges

Christophe Ballif, Jacques Levrat, Mathieu Gérard Boccard, Matthieu Despeisse, Olivier Denis Dupré

The power produced by a photovoltaic module is not simply the sum of the powers of its constituents cells. The difference stems from a number of so-called “cell-to-module” (CTM) gain or loss mechanisms. These are getting more and more attention as improvem ...

2018

Quantifying and Modeling the Impact of Interconnection Failures on the Electrical Performance of Crystalline Silicon Photovoltaic Modules

Christophe Ballif, Antonin Faes, Jacques Levrat, Matthieu Despeisse, Eleonora Annigoni, Alessandro Francesco Aldo Virtuani

We present an electrical model developed with LT SPICE that simulates the performance of a string of cells with disconnections in the electrical circuit. In a previous contribution, we quantified experimentally how the module performance is affected when o ...

IEEE2018

The impact of silicon solar cell architecture and cell interconnection on energy yield in hot & sunny climates

Christophe Ballif, Jacques Levrat, Stefaan De Wolf, Matthieu Despeisse, Jean Cattin, Yannick Samuel Riesen, Johannes Peter Seif, Andrea Tomasi, Jan Haschke, Brahim Aissa

Extensive knowledge of the dependence of solar cell and module performance on temperature and irradiance is essential for their optimal application in the field. Here we study such dependencies in the most common high-efficiency silicon solar cell architec ...

Royal Soc Chemistry2017

Increasing the efficiency of silicon heterojunction solar cells and modules by light soaking

Christophe Ballif, Antoine Descoeudres, Jacques Levrat, Stefaan De Wolf, Franz-Josef Haug, Matthieu Despeisse, Eiji Kobayashi

Silicon heterojunction solar cells use crystalline silicon (c-Si) wafers as optical absorbers and employ bilayers of doped/intrinsic hydrogenated amorphous silicon (a-Si:H) to form passivating contacts. Recently, we demonstrated that such solar cells incre ...

Elsevier Science Bv2017

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

Realization of GaInP/Si Dual-Junction Solar Cells With 29.8% 1-Sun Efficiency

Christophe Ballif, Antoine Descoeudres, Nicolas Badel, Antonin Faes, Jacques Levrat, Matthieu Despeisse, Loris Barraud, Bertrand Yves Paul Paviet-Salomon, Stephanie Essig

Combining a Si solar cell with a high-bandgap top cell reduces the thermalization losses in the short wavelength and enables theoretical 1-sun efficiencies far over 30%. We have investigated the fabrication and optimization of Si-based tandem solar cells w ...

Ieee-Inst Electrical Electronics Engineers Inc2016

Biexcitonic molecules survive excitons at the Mott transition

Jean-François Carlin, Benoît Marie Joseph Deveaud, Jean-Daniel Ganière, Jacques Levrat, Nicolas Grandjean, Raphaël Butté, Eric Feltin, Mehran Shahmohammadi, Georg Rossbach, Gwénolé Jean Jacopin

When the carrier density is increased in a semiconductor, according to the predictions of Sir Nevil Mott, a transition should occur from an insulating state consisting of a gas of excitons to a conductive electron-hole plasma. This crossover, usually refer ...

Nature Publishing Group2014

Q-factor of (In,Ga)N containing III-nitride microcavity grown by multiple deposition techniques

Jean-François Carlin, Gatien Cosendey, Jacques Levrat, Nicolas Grandjean, Raphaël Butté, Marlene Glauser, Georg Rossbach

A 3 lambda/2 (In,Ga)N/GaN resonant cavity, designed for similar to 415nm operation, is grown by molecular beam epitaxy and is sandwiched between a 39.5-period (In,Al)N/GaN distributed Bragg reflector (DBR), grown on c-plane GaN-on-sapphire pseudo-substrate ...

Amer Inst Physics2013

Impact of saturation on the polariton renormalization in III-nitride based planar microcavities

Jean-François Carlin, Jacques Levrat, Nicolas Grandjean, Raphaël Butté, Eric Feltin, Georg Rossbach

It has been widely observed that an increasing carrier density in a strongly coupled semiconductor microcavity (MC) alters the dispersion of cavity polaritons, below and above the condensation threshold. The interacting nature of cavity polaritons stems fr ...

Amer Physical Soc2013

Generic picture of the emission properties of III-nitride polariton laser diodes: Steady state and current modulation response

Jacques Levrat, Nicolas Grandjean, Raphaël Butté, Marlene Glauser, Georg Rossbach, Munise Nevin Cobet

The main emission characteristics of electrically driven polariton lasers based on planar GaN microcavities with embedded InGaN quantum wells are studied theoretically. The polariton emission dependence on pump current density is first modeled using a set ...

Amer Physical Soc2012

Nonlinear emission properties of an optically anisotropic GaN-based microcavity

Gatien Cosendey, Jacques Levrat, Nicolas Grandjean, Raphaël Butté, Marlene Glauser, Georg Rossbach, Munise Nevin Cobet

The pronounced optical in-plane anisotropy of a suitably designed nonpolar GaN-based microcavity, mainly inherited from the valence-band complexity of wurtzite semiconductors, allows the coexistence of two different light-matter coupling regimes along orth ...

Amer Physical Soc2012

Impact of biexcitons on the relaxation mechanisms of polaritons in III-nitride based multiple quantum well microcavities

Jean-François Carlin, Benoît Marie Joseph Deveaud, Jean-Daniel Ganière, Jacques Levrat, Nicolas Grandjean, Raphaël Butté, Eric Feltin, Gabriel Christmann, Pierre Michel Corfdir, Georg Rossbach

We report on the direct observation of biexcitons in a III-nitride based multiple quantum well microcavity operating in the strong light-matter coupling regime by means of nonresonant continuous wave and time-resolved photoluminescence at low temperature. ...

2012

High quality factor two dimensional GaN photonic crystal cavity membranes grown on silicon substrate

Jean-François Carlin, Romuald Houdré, Jacques Levrat, Nicolas Grandjean, Raphaël Butté, Kirill Atlasov, Antonino Francesco Castiglia, Ulagalandha Perumal Dharanipathy, Noelia Vico Triviño, Georg Rossbach

We report on the achievement of freestanding GaN photonic crystal L7 nanocavities with embedded InGaN/GaN quantum wells grown by metal organic vapor phase epitaxy on Si (111). GaN was patterned by e-beam lithography, using a SiO2 layer as a hard mask, and ...

American Institute of Physics2012

Physics of Polariton Condensates in GaN-based Planar Microcavities

Jacques Levrat

Since its prediction in 1996 by Imamoğlu and coworkers, the use of a non-equilibrium polariton condensate to produce an intense coherent light source referred to as a polariton laser has attracted a lot of interest in the whole physics community as it ...

EPFL2012

Intrinsic dynamics of weakly and strongly confined excitons in nonpolar nitride-based heterostructures

Benoît Marie Joseph Deveaud, Jean-Daniel Ganière, Jacques Levrat, Nicolas Grandjean, Pierre Michel Corfdir

Both weakly and strongly confined excitons are studied by time-resolved photoluminescence in a nonpolar nitride-based heterostructure grown by molecular beam epitaxy on the a-facet of a bulk GaN crystal, with an ultralow dislocation density of 2 × 105 cm-2 ...

2011

One-dimensional exciton luminescence induced by extended defects in nonpolar GaN/(Al,Ga)N quantum wells

Benoît Marie Joseph Deveaud, Jean-Daniel Ganière, Pierre Stadelmann, Denis Martin, Jacques Levrat, Nicolas Grandjean, Raphaël Butté, Yadira Arroyo Rojas Dasilva, Tiankai Zhu, Pierre Michel Corfdir

In this study, we present the optical properties of nonpolar GaN/(Al,Ga)N single quantum wells (QWs) grown on either a- or m-plane GaN templates for Al contents set below 15%. In order to reduce the density of extended defects, the templates have been proc ...

Institute of Physics2011