Recherche

Afficher tous les résultats pour

Accueil

Personne

Jakub Holovsky

Cette personne a quitté l’EPFL

À propos
Confidentialité
Mentions légales

Graph Chatbot

Publications associées (21)

Page 1 sur 2

Effect of the thin-film limit on the measurable optical properties of graphene

Christophe Ballif, Stefaan De Wolf, Sylvain Nicolay, Jakub Holovsky

The fundamental sheet conductance of graphene can be directly related to the product of its absorption coefficient, thickness and refractive index. The same can be done for graphene's fundamental opacity if the so-called thin-film limit is considered. Here ...

Nature Publishing Group2015

New metric for carrier selective contacts for silicon heterojunction solar cells

Mathieu Gérard Boccard, Jakub Holovsky

Heterojunction carrier selective contacts for solar cells have gained great attention because of the ability of these contacts to efficiently collect majority carriers while hindering the recombination of minority carriers, thus resulting in the highest re ...

PERGAMON-ELSEVIER SCIENCE LTD2022

Enhancing the optoelectronic properties of amorphous zinc tin oxide by subgap defect passivation: A theoretical and experimental demonstration

Christophe Ballif, Aïcha Hessler-Wyser, Quentin Thomas Jeangros, Monica Morales Masis, Jakub Holovsky, Oscar Esteban Rucavado Leandro, Federica Landucci

The link between sub-bandgap states and optoelectronic properties is investigated for amorphous zinc tin oxide (a-ZTO) thin films deposited by RF sputtering. a-ZTO samples were annealed up to 500 °C in oxidizing, neutral, and reducing atmospheres before ch ...

American Physical Society2017

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

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

A New View of Microcrystalline Silicon: The Role of Plasma Processing in Achieving a Dense and Stable Absorber Material for Photovoltaic Applications

Christophe Ballif, Matthieu Despeisse, Jakub Holovsky, Grégory Bugnon, Peter Cuony, Gaetano Parascandolo, Simon Hänni

To further lower production costs and increase conversion efficiency of thin-film silicon solar modules, challenges are the deposition of high-quality microcrystalline silicon (μc-Si:H) at an increased rate and on textured substrates that guarantee efficie ...

2012

Quantitative Analysis of Nanorough Hydrogenated Si(111) Surfaces through Vibrational Spectral Assignment by Periodic DFT Calculations br

Christophe Ballif, Stefaan De Wolf, Jakub Holovsky

In this work, we use periodic density functional theory(periodic DFT) to rigorously assign vibrational spectra measured on nanorough wet-processed hydrogenated Si(111) surfaces. We compare Si(111)-(1x1) surfaces etched by dilute HF and NH4F, featuring two ...

AMER CHEMICAL SOC2022

Towards Quantitative Interpretation of Fourier-Transform Photocurrent Spectroscopy on Thin-Film Solar Cells

Franz-Josef Haug, Michael Elias Stückelberger, Jakub Holovsky

The method of detecting deep defects in photovoltaic materials by Fourier-Transform Photocurrent Spectroscopy has gone through continuous development during the last two decades. Still, giving quantitative predictions of photovoltaic device performance is ...

2020

Thin-film limit formalism applied to surface defect absorption

Christophe Ballif, Jakub Holovsky

The thin-film limit is derived by a nonconventional approach and equations for transmittance, reflectance and absorptance are presented in highly versatile and accurate form. In the thin-film limit the optical properties do not depend on the absorption coe ...

Optical Society of America2014

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

Improved amorphous/crystalline silicon interface passivation by hydrogen plasma treatment

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

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

Amorphous/Crystalline Silicon Interface Stability: Correlation between Infrared Spectroscopy and Electronic Passivation Properties

Christophe Ballif, Stefaan De Wolf, Jakub Holovsky, Silvia Martin de Nicolas Agut

Ultrathin layers of hydrogenated amorphous silicon (a-Si:H), passivating the surface of crystalline silicon (c-Si), are key enablers for high-efficiency silicon heterojunction solar cells. In this work, the authors apply highly sensitive attenuated total r ...

WILEY2020

Time evolution of surface defect states in hydrogenated amorphous silicon studied by photothermal and photocurrent spectroscopy and optical simulation

Christophe Ballif, Matthieu Despeisse, Michael Elias Stückelberger, Jakub Holovsky

The time evolution of surface defect density and width of space charge region in thin layer of amorphous silicon is observed experimentally by Fourier transform photocurrent spectroscopy. This work reviews the assumption that photocurrent is insensitive to ...

Elsevier Science Bv2012

Illumination-Dependent Requirements for Heterojunctions and Carrier-Selective Contacts on Silicon

Mathieu Gérard Boccard, Jakub Holovsky, Luca Massimiliano Antognini

High efficiency silicon solar cells generally feature heterojunction or carrier-selective contact architectures, for which there is current interest in developing structures using a wide range of materials. The electrical and optical requirements that thes ...

2020

Below the Urbach Edge: Solar Cell Loss Analysis Based on Full External Quantum Efficiency Spectra

Stefaan De Wolf, Jakub Holovsky, Xin Yu Chin

We suggest a new solar cell loss analysis using theexternal quantumefficiency (EQE) measured with sufficiently high sensitivity to alsoaccount for defects. Unlike common radiative-limit methods, wherethe impact of deep defects is ignored by exponential ext ...

AMER CHEMICAL SOC2023

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

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

Raman Spectroscopy of Organic-Inorganic Halide Perovskites

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

Highly Conductive and Broadband Transparent Zr-Doped In2O3 as Front Electrode for Solar Cells (vol 8, pg 1202, 2018)

Christophe Ballif, Matthieu Despeisse, Mathieu Gérard Boccard, Loris Barraud, Jakub Holovsky, Monica Morales Masis, Oscar Esteban Rucavado Leandro, Raphaël Monnard

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC2019

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

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

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

Correlating light-induced deep defects and phase segregation in mixed-halide perovskites

Quentin Thomas Jeangros, Jakub Holovsky, Christian Michael Wolff, Peter Joseph Fiala, Xin Yu Chin

Mixed-halide perovskites are highly promising materials for tandem solar cells. The phenomenon of phase segregation, however hinders their application. Here, we combine Fourier-Transform photocurrent spectroscopy with photoluminescence and current density- ...

Royal Society of Chemistry2022

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

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

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