Prof. Dr. Natalie Banerji

Natalie Banerji is currently a Full Professor of Chemistry at the University of Bern and leads the FemtoMat group. Her research interests include the study of organic and hybrid materials using ultrafast spectroscopic techniques, in view of solar cell and bioelectronic applications. She studied Chemistry at the University of Geneva and obtained her Ph.D. in Physical Chemistry in 2009, under the supervision of Prof. Eric Vauthey. She then moved to the University of California in Santa Barbara (USA), to work on organic solar cells during a Post-Doctoral stay with Nobel Laureate Prof. Alan J. Heeger (2009–2011). In 2011, she started her independent research career in Switzerland at the Ecole Polytechnique Fédérale de Lausanne (EPFL) with an Ambizione Fellowship by the Swiss National Science Foundation (SNSF). She moved to the University of Fribourg in 2014, was subsequently nominated Associate Professor in 2015, and presided the Chemistry Department in Fribourg form 2016–2017.

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Senior researchers

Dr. Julien Réhault

Julien joined the FemtoMat group as a PostDoc in August 2017 and became Research Associate in June 2018. His research interests involve any kind of Ultrafast Laser Spectroscopy ranging from the ultraviolet to the Terahertz. He is mainly involved in developing new tools for the field of Organic Bioelectronics, especially in the Terahertz.

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Dr. Demetra Tsokkou

Demetra is currently a researcher assistant in the FemtoMat group. She joined the group as a Post-Doctoral Researcher in February 2015. She obtained her Ph.D. at the University of Cyprus on the synthesis and photophysics of inorganic semiconducting nanowires. Her current research is focused on the transport properties and electronic structure of doped organic materials (small molecules and polymers) via ultrafast spectroscopic techniques, such as time domain THz and absorption spectroscopy.

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Dr. Olivier Bardagot

Olivier started his Post-Doctoral position in the FemtoMat group in 2020 to join the bio-electronics team in their investigations of accumulation mode Organic ElectroChemical Transistor (OECT) devices. From 2023 on, he participates at a 20% capacity while developing his own research activity as tenured researcher at CNRS (ICPEES, France) focusing on highly structured polymer films for OECTs and thermoelectricity.


Dr. Kaila Yallum

After obtaining a Bachelor’s degree at Northeastern University in 2017, Kaila joined the FemtoMat group as a Masters student in 2018 and started as Ph.D. student in September 2019. She uses multiple spectroscopic techniques to investigate charge generation in organic photovoltaic materials such as Transient Absorption, Electromodulated Differential Absorption, and Excitation Correlation Spectroscopy.

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Ph.D. students

Eva Röck

Eva graduated with a Master of Science in Physics from the University of Vienna in 2020, where she specialized in Electronic Properties of Materials and Spectroscopy. She joined the FemtoMat group as a Ph.D. student to investigate doped organic semiconductors. Her current project focuses on charge transport in doped organic semiconductors using temperature dependent THz time domain spectroscopy.

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Cedric Hoffmann

Cedric joined the FemtoMat group as a Ph.D. student in May 2021. He obtained his Master’s degree in Chemistry at Technical University of Dresden in 2021, where he worked on organic semiconducting materials and organic electrochemical transistors.

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Isabelle Holzer

Isabelle joined the FemtoMat group in January 2021 as a Master student and started as a Ph.D. student in March 2022. She currently investigates chemical and electrochemical doping of different semiconducting materials using multiple spectroscopic techniques such as THz spectroscopy, spectroelectrochemistry and Raman spectroscopy.

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Kaishuai Zhang

Kaishuai joined the FemtoMat group in August 2022 as a Ph.D. student focused on spectroelectrochemistry of glycolated polymers and 2D materials.

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Christian Franz

Christian joined the FemtoMat group in February 2022 for his Master’s project, which involved treatment effects on PEDOT:PSS. In April 2023, he started with his Ph.D. focusing on electrochemical doping of organic semiconductors, especially the effect of side chains on the electrolyte–polymer interaction.

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Maximilian Horn

Maximilian obtained his B.Sc. degree in Chemistry from the University of Würzburg in 2021. He then moved to Hamburg for his Master’s studies and joined the FemtoMat group in September 2022 for an Erasmus internship focusing on chemical doping of glycolated polymers. In November 2023, he started with his Ph.D. where he will focus on the investigation of organic photocatalysts.

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Basil Hunger

Basil completed his Bachelor’s studies in Chemistry and Molecular Sciences at the University of Bern in 2022. He joined the FemtoMat group for his Bachelor project, continued with his Master’s thesis on the doping of different polythiophenes and joined recently for his Ph.D. project.

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Visiting researchers

Md Soif Ahmed

Md Soif Ahmed is a Ph.D. student in the Department of Physics at the Indian Institute of Technology Hyderabad. He completed his integrated M.Sc. in Physics from Aliah University, Kolkata, in 2018. Ahmed was awarded a ‘Research Fellowship’ through the Swiss Government Excellence Scholarship, allowing him to spend one year conducting research at the University of Bern under the guidance of Prof. Natalie Banerji. Currently, he is actively involved in cutting-edge research within the FemtoMat group, focusing primarily on the excited-state dynamics and spectroscopic investigation of lead-free halide double perovskite nanocrystals. This involves utilizing advanced techniques such as ultrafast transient absorption and optical–pump–terahertz–probe spectroscopy.

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Former Group Members