Publications de Gabriel Christmann

Palliating the efficiency loss due to shunting in perovskite/silicon tandem solar cells through modifying the resistive properties of the recombination junction

Christophe Ballif, Gabriel Christmann, Mathieu Gérard Boccard, Sylvain Nicolay

As the efficiency of commercial crystalline silicon solar cells approaches its maximum theoretical value, tandem architectures are becoming increasingly popular to continue the push to higher photovoltaic performances. Thin-film materials are particularly ...

2021

Advanced method for electrical characterization of carrier-selective passivating contacts using transfer-length-method measurements under variable illumination

Christophe Ballif, Antoine Descoeudres, Mathieu Gérard Boccard, Gabriel Christmann, Bertrand Yves Paul Paviet-Salomon, Jonas Geissbühler, Nicolas Badel, Laurie-Lou Senaud, Matthieu Despeisse, Sylvain Nicolay

2021

Performance Limitations and Analysis of Silicon Heterojunction Solar Cells Using Ultra-Thin MoOx Hole-Selective Contacts

Christophe Ballif, Gabriel Christmann, Mathieu Gérard Boccard, Luca Massimiliano Antognini, Jean Cattin, Julie Amandine Dreon, Vincent Philippe Paratte

We recently showed that silicon heterojunction solar cell with MoOx-based hole-selective contact could reach 23.5% in efficiency with MoOx layers of 4 nm. Such thin MoOx layer enables a considerable current-density gain of over 1 mA/cm(2) compared to the u ...

2021

Lateral transport in silicon solar cells

Christophe Ballif, Gabriel Christmann, Mathieu Gérard Boccard, Jan Haschke

We investigate lateral charge carrier transport in crystalline silicon solar cells. Under typical operation illumination of high-efficiency solar cells, a significant population of electrons and holes exist in the silicon wafer, leading to a non-negligible ...

AIP2020

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

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

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

Rear-emitter silicon heterojunction solar cells with atomic layer deposited ZnO:Al serving as an alternative transparent conducting oxide to In2O3:Sn

Christophe Ballif, Antoine Descoeudres, Gabriel Christmann, Nicolas Badel, Matthieu Despeisse, Sylvain Nicolay, Loris Barraud

Here high-efficiency (above 21%) large-area silicon heterojunction solar cells with atomic layer deposited ZnO:Al as front- or back-side transparent conducting oxide are demonstrated. Photoconductance decay measurements indicate that the excellent chemical ...

2019

Complex Refractive Indices of Cesium–Formamidinium-Based Mixed-Halide Perovskites with Optical Band Gaps from 1.5 to 1.8 eV

Christophe Ballif, Jérémie Werner, Quentin Thomas Jeangros, Matthias Wolfgang Bräuninger, Gabriel Christmann, Florent Sahli, Arnaud Walter, Sylvain Nicolay, Björn Niesen, Gizem Nogay

Cesium-formamidinium-based mixed-halide perovskite materials with optical band gaps ranging from 1.5 to 1.8 eV are investigated by variable-angle spectroscopic ellipsometry. The determined complex refractive indices are shown to depend on the fabrication p ...

2018

Piezoelectric and structural properties of c-axis textured aluminium scandium nitride thin films up to high scandium content

Paul Muralt, Gabriel Christmann, Sylvain Nicolay, Stefan Mertin

2018

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

Christophe Ballif, Quentin Thomas Jeangros, Antoine Descoeudres, Antonin Faes, Gabriel Christmann, Jonas Geissbühler, Matthieu Despeisse, Bertrand Yves Paul Paviet-Salomon, Stefaan De Wolf, Nicolas Badel

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

Enhanced piezoelectric properties of c-axis textured aluminium scandium nitride thin films with high scandium content: influence of intrinsic stress and sputtering parameters

Paul Muralt, Gabriel Christmann, Stefan Mertin, Silviu Cosmin Sandu, Vladimir Pashchenko, Clemens Benedict Nyffeler, Mohammad Fazel Parsapour Kolour

Aluminium scandium nitride (ASN) exhibits a largely enhanced piezoelectric response as compared to aluminium nitride (AlN), which makes it an upcoming piezoelectric material for use in next generation RF filters, sensors, actuators and energy harvesting de ...

Ieee2017