Publications by Sofia Libraro | EPFL Graph Search

Co-annealing of PECVD boron emitters and poly-Si passivating contacts for leaner TOPCon solar cell fabrication

Christophe Ballif, Franz-Josef Haug, Julien Hurni, Ezgi Genç, Sofia Libraro

This study investigates the feasibility of a single-step annealing process for tunnel oxide passivating contact (TOPCon) solar cell fabrication to replace the conventional two-step approach. We present a novel method using a single thermal treatment to sim ...

2025

Impact of Rapid Thermal Processing on Bulk Lifetime and Surface Recombination Velocity of Crystalline Silicon With Passivating Tunnel Oxide Contacts

Christophe Ballif, Franz-Josef Haug, Julien Hurni, Ezgi Genç, Sofia Libraro, Audrey Marie Isabelle Morisset

We investigate rapid thermal processing (RTP) as alternative to the prolonged thermal annealing process used to form tunnel-oxide passivating contacts for silicon solar cells. The thermal treatment is generally followed by hydrogenation to passivate defect ...

Wiley2025

Microstructural and electrical characterization of high temperature passivating contacts for silicon solar cells

Sofia Libraro

Recombination at metal/semiconductor interfaces represents the main limitation in mainstream c-Si solar cells, primarily based on the passivated emitter and rear cell (PERC) concept. Full-area passivating contacts based on SiOx/poly-Si stacks are a candida ...

EPFL2024

Hole-Selective SiNx and AlOx Tunnel Nanolayers for Improved Polysilicon Passivating Contacts

Franz-Josef Haug, Ezgi Genç, Sofia Libraro, Audrey Marie Isabelle Morisset

A highly efficient hole-selective passivating contact remains the crucial step required to increase the efficiency of polysilicon-based Si solar cells. The future development of solar modules depends on a device structure that can complement the electron-s ...

2024

Development and characterization of N2O-plasma oxide layers for high-temperature p-type passivating contacts in silicon solar cells

Christophe Ballif, Aïcha Hessler-Wyser, Franz-Josef Haug, Julien Hurni, Ezgi Genç, Sofia Libraro, Audrey Marie Isabelle Morisset, David Fernando Reyes Vasquez

Full-area passivating contacts based on SiOx/poly-Si stacks are key for the new generation of industrial silicon solar cells substituting the passivated emitter and rear cell (PERC) technology. Demonstrating a potential efficiency increase of 1 to 2% compa ...

American Chemical Society (ACS)2024

Interactions between aluminium and fired passivating contacts during fire-through metallization (vol 249, 112051, 2023)

Christophe Ballif, Aïcha Hessler-Wyser, Antoine Descoeudres, Franz-Josef Haug, Mario Joe Lehmann, Andrea Ingenito, Sofia Libraro

Elsevier2024

22.8% full-area bifacial n-PERT solar cells with rear side sputtered poly-Si (n) passivating contact

Christophe Ballif, Sylvain Nicolay, Bertrand Yves Paul Paviet-Salomon, Andrea Ingenito, Sofia Libraro

High-temperature compatible passivating contacts based on phosphorus doped polysilicon (poly-Si(n)) on a thin silicon oxide, employed on the rear side of bifacial n-PERT like solar cells provide an efficiency increase while being compatible with current ph ...

ELSEVIER2023

Understanding and mitigating resistive losses in fired passivating contacts: role of the interfaces and optimization of the thermal budget

Christophe Ballif, Aïcha Hessler-Wyser, Franz-Josef Haug, Luca Massimiliano Antognini, Julien Hurni, Ezgi Genç, Sofia Libraro, Audrey Marie Isabelle Morisset

This work presents a study of p-type passivating contacts based on SiCx formed via a rapid thermal processing (RTP) step, using conditions compatible with the firing used to sinter screen-printed metallization pastes in industry. The contributions of the t ...

Elsevier2023

Interactions between aluminium and fired passivating contacts during fire-through metallization

Christophe Ballif, Aïcha Hessler-Wyser, Franz-Josef Haug, Mario Joe Lehmann, Sofia Libraro

Replacing silver metallization with earth-abundant materials in Si solar cells is a critical step towards the sustainable growth of photovoltaics. In this work, we investigate fire-through processes using Al for the metallization of solar cells with p-type ...

ELSEVIER2023

Impact of rapid thermal processing on bulk and surface recombination mechanisms in FZ silicon with fired passivating contacts

Christophe Ballif, Franz-Josef Haug, Mario Joe Lehmann, Andrea Ingenito, Sofia Libraro, Audrey Marie Isabelle Morisset

We investigate bulk and interface recombination in crystalline silicon with p-type fired passivating contacts. These consist of a chemical oxide and an in-situ doped layer of SiCx with low carbon content. Following a rapid thermal annealing to activate the ...

ELSEVIER2022

Implementation and understanding of p plus fired rear hole selective tunnel oxide passivating contacts enabling > 22% conversion efficiency in p-type c-Si solar cells

Christophe Ballif, Sylvain Nicolay, Philippe Wyss, Franz-Josef Haug, Matthieu Despeisse, Andrea Ingenito, Sofia Libraro

Passivating contacts are key enablers for high efficiency c-Si solar cells. Here, we present our latest advancement in terms of implementation and understanding in fired passivating contacts (FPC) used as rear p + passivating contact in p-type solar cells. ...

ELSEVIER2021

Contributions to the contact resistivity in fired tunnel-oxide passivating contacts for crystalline silicon solar cells

Christophe Ballif, Franz-Josef Haug, Frank Meyer, Andrea Ingenito, Sofia Libraro

We investigate the contact resistivity of p-type passivating contacts for silicon solar cells. Our contact structures are compatible with firing, a rapid annealing process similar to the one used for sintering of the screen-printed metallisation in solar c ...

2019