Group Picture July 2021
The Weber group as of July 2021. An updated group foto will follow shortly

The P.I.: Stefan Weber

Stefan Weber

Stefan studied Physics at the University of Konstanz. Already as an undergrad student he started to work with an SFM in the group of Prof. Leiderer. For his diploma thesis under the supervision of Prof. Dr. Johannes Boneberg he studied the interaction of gold nanoparticles with pulsed laser light.

In 2007, he joined the group of Prof. Butt at the Max Planck Institute for Polymer Reaearch (MPI-P), Mainz. During his PhD, he spent six months at Seoul National University, Korea, in the groups of Prof. K. Char and Prof. C. Lee. In 2010 he received a joint doctoral degree from Mainz University and SNU. In 2011 he went to University College Dublin as a Feodor Lynen Fellow (Alexander von Humboldt Foundation) to join Prof. Brian Rodriguez and Prof. Suzi Jarvis. In 2012 he became a group leader in the Physics of Interfaces group in the department of Prof. Hans-Jürgen Butt at the Max Planck Institute for Polymer Research (MPI-P), Mainz. From 2015 to 2023 he held a junior professor postition in the Physics department of Mainz University.

Sind June 2023, he is a permament group leader at the Institute for Photovoltaics at University Stuttgart, where he heads the Nanoscale Microscopy and Characterization group. In 2024, he won an ERC Consolidator grant for the development of a Photovoltaic Microscope that combines nanoscale electrical imaging with high-resolution optical microscopy and ultrafast spectroscopy.

Next to force microscopy, Stefan Weber is a passionate photographer, chorister and widely feared for his puns during group meetings… Stefan Weber is a very common name. In case you were looking for someone else, you might find him here.

Team Stuttgart

Do you want to be part of the Nanoscale Microscopy Team at the Institute for Photovoltaics? Then reach out to me, we might have someting for you!


Dr. Asfaw Negash

Asfaw joined the group as a Alexander von Humboldt fellow to improve the stability of perovskite solar cells. He studied Chemistry at Alemaya University, Ethiopia, where he got his Bachelor’s degree in 2003. In 2010, he got his Master’s degree in Physical Chemistry from Addis Ababa University, Ethiopia. He then did his PhD on “Solution-processible Organic Solar Cells based on Fullerene and Non-Fullerene Acceptors” in a joint PhD program with Hasselt University, Belgium, and Addis Ababa University, Ethiopia.

Dr. Shaghayegh Saeidiharzand

Shaghayegh joined the group in May 2024. He will add a self-description shortly.

PhD Students

Martina Pesci

As a fan of survival videogames with little time to play and after attending a language high school, Martina decided to start a Bachelor in Chemistry to experience horror in real life. After surviving the Bachelor in 2019, motivated by a sincere affection for the anxiety arisen from it the interest in material properties and characterization, she completed a Master’s degree in Physical and Inorganic Chemistry with a thesis on the thermal decomposition of formamidinium tin triiodide perovskite (FASnI3) at Sapienza Università di Roma.

Currently, she is working for a scanning force microscopy guy (see above) with decent musical taste on investigating the electrical properties of the interfaces in all-perovskite tandem solar cells by Kelvin Probe Force Microscopy. In fact, if Ph.D. is a journey, she wanted to make sure the playlist at least didn’t suck.

Timo Eberle

Timo joined the group in February 2024. He will add a self-description shortly.

Team Mainz

The team Mainz is based at the Physics at Interfaces group of Prof. Butt at MPI for Polymer Research.

Konstantinos Bidinakis

Kostas studied Chemical Engineering in Athens before moving to Imperial College London to do his Master’s, where he studied perovskite solar cells with impedance spectroscopy.

In January 2020 he started his PhD in Stefan’s group on cross-sectional KPFM on perovskite solar cells. He is our expert for (unfocused) ion beam milling.

Pravash Bista

Ever since he started his PhD in 2021, Pravash Bista is our best PhD student from Nepal. He joined the team as a research assistant already in August 2018. He did his Bachelor thesis on the nanoscale degradation of perovskite thin films in Spring 2019. In 2021 he finished his Master thesis on slide electrification of water droplets on hydrophobic surfaces, which is also the topic of his PhD thesis.

Besides science, he is also a world-class table tennis player and tries to spend most of his free time with his friends. Singing and traveling are some of his hobbies.

Pascal Rohrbeck

Pascal is our Chemistry expert from the „other (eebsch) side of the Rhine“. Before he started as a PhD student on interfaces in perovskite solar cells, he investigated the nanoscale electrical response of photovoltaic perovskite films with time-resolved KPFM in his Master thesis. He is widely known as the „Golden Boy of electrical AFM“.

Next to his activities in the local JCF-GDCh (forum for young chemists), Pascal is also a passionate volleyball player.

Franjo Weber

Franjo did his Master thesis under the joint supervision of Stefan and Rüdiger Berger. He is our battery expert developing BS* methods to study solid-state batteries. He now does his PhD in Rüdiger’s group, but deep in heart he is still a „Weberknecht“.

Besides his love for dad jokes and puns, Franjo is a passionate football fan who never misses any Mainz05 or BvB Dortmund matches.

*BS stands for bias spectroscopy… OF COURSE!!!

In between…

Amelie Axt

Amelie studied Physics in Mainz. Before starting her masters thesis in Stefan’s group she joined the group of David Haviland at the KTH in Stockholm for an internship, learning a new multi-frequency SFM technique called intermodulation. For her masters thesis she further investigated this method for force field mapping at solid-liquid interfaces. In her PhD she extends these methods to open-loop KPFM methods for mapping electrical potentials at solid-liquid interfaces. In a collaboration with the Biochemisty Department at JGU she investigates the various shapes of the IM30 membrane protein.

Besides her activities in university sports she has a passion for painting and drawing.

Soon-to-be a doctor, she recently disappeared to play with more fancy AFMs started working for AFM industry.


Lukas Cavar

Lukas joined Stefan’s group for a lab internship of his Physics study in 2022. He became the master of the sidebands and orchestrated the most sophisticated KPFM and EFM experiments the world has ever seen. He’s now a PhD student in Prof. Wittmann’s group at JGU Mainz.

Yenal Yalçınkaya

Yenal, a passionate tree-hugger and world-famous expert in significant digits, successfully finished his PhD in early 2024 and moved to Konstanz, where he joined the team of Lukas Schmidt-Mende for a postdoc.

Miriam Weigand

Miriam joined the group for her Bachelor thesis, where she explored new ways of measururing slide electrification effects in moving drops.

Noah Leuschen

Having mastered all of our fancy electrical AFM modes, Noah tortured Perovskite thin films for his Bachelor’s thesis (a.k.a. „degradation in ambient air“) and watched them how they disintegrated.

Mara Niebling

Mara joined the group in march 2021 and quickly became our Python queen, taming our solar cell testing setup. In her bachelor thesis she developed a new bias scanning KPFM mode.

Peter Reichel

In his bachelor thesis he investigated new spectroscopic KPFM methods to learn more about capacity gradients (and the gradients thereof). Warning! Peter is a semi-professional American Football quarterback, so don’t cross him after dark!

Dr Aránzazu Sierra Fernandez

Arancha has a strong affection for old stones. During her EU-funded Marie-Curie Project, she joined us for eight months to investigate the nanoscale mechanical properties of her self-developed stone protection coatings using AFM and Nonoindentation.

Ilka Hermes

Ilka investigated ferroic structures in hybrid perovskite films and their effect on charge carrier dynamics. She occasionally drops by to yell at our gloveboxes. After graduating and a couple of years at Park AFM, in 2022 she started as a junior group leader at Leibniz Institute for Polymer Research Dresden.

Dr Amy Stetten

Amy spent three years as a postdoc in Stefan’s group, where she combined her background in capillary physics with this group’s expertise in electronics and KPFM to study charge separation between liquid drops and solid surfaces. In early 2021 she moved to University of Twente to the group of Frieder Mugele.

Ravi Gowdru Manjunata

Ravi investigated the nanoscale stucture and mechanical properties of cellulose nanofibres.

Thomas Gries

Thomas joined Stefan’s group in 2021 for his Master thesis on surface passivation and characterization of perovskite films.

Jonas Paulus

Jonas finished his bachelor thesis in March 2021 on the development of a solar cell testing and characterization programm.

Lukas Odenbreit

Lukas finished his bachelor thesis on the measurement of capillary waves on water in 2020.

Victor Bergmann

Victor finished his PhD thesis on the development of cross sectional KPFM on perovskite solar cells in 2020.

Since May 2017 he is working for Park AFM. Next to his many other activities, he is a successful innkeeper: Together with friends he started the Bar Gutleut in Mainz.

Leonard Winkelmann

Leonard finished his master thesis on the behavior of ferroelastic twin domains in perovskite crystals in 2019.

Christopher Gort

Chris finished his master thesis on time resolved KPFM methods applied on perovskite solar cells in 2019 and his bachelor thesis on the investigation of mixed perovskites in 2016.

Niklas Budinger

Niklas (II) finished his bachelor thesis on numerical simulations of ion dynamics in perovskite solar cells in 2017.

Niklas Tausendpfund

Niklas (I) finished his bachelor thesis on open- and closed loop Kelvin probe force mciroscopy in 2016.

Stanislav Khodorov

Stanislav did his bachelor thesis on self-organizing nano-catarpillar structures in 2015.