The team

Weber group picture

Stefan AL 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 his PhD thesis in the group of Prof. Hans-Jürgen Butt/Dr. Rüdiger Berger at the Max Planck Institute for Polymer Reaearch (MPI-P), Mainz, he used and developed electrical scanning force microscopy methods for the investigation of organic optoelectronic materials. The project was embedded in the international research training group (IRTG) "Self-organizing materials for optoelectronics" - a joint graduate school between University and MPI-P in Mainz and the Seoul National University (SNU) and Hannam University Daejon in South Korea. In 2009 and 2010 he spent 6 months at SNU in the groups of Prof. Kookheon Char and Prof. Changhee 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). Together with Prof. Brian Rodriguez and Prof. Suzi Jarvis he developed a new method for mapping surface potentials in liquid electrolytes. Here, he could demonstrate that atomic scale imaging is possible even in very viscous media like glycerol.

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. In 2015 he was appointed as a junior professor in the Physics department of Mainz University. Curriculum vitae.

Next to force microscopy, Stefan Weber is a passionate photographer and member of the university choir Mainz.

Stefan Weber is a very common name. In case you were looking for someone else, you might find him here.

PhD Students

Pascal Rohrbeck

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.

Pravash Bista

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.

Yenal Yalçınkaya


Yenal studied Materials Science and Engineering at Gebze Technical University in Kocaeli/Turkey.

In March 2020, he started his PhD in Stefan's group where he is investigating (taming) perovskite single crystals and films with PFM and KPFM. He is working in the DFG SPP 2196 "Perovskite semiconductors: From fundamental properties to devices".

Yenal likes trees and is a very friendly and modest person as long as he's not doing any sports where he is allowed to tackle his opponents.

Kostas 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.

"In between"

Not quite finished yet, but already working in the AFM industy:

Amelie Axt

Amelie Axt

Amelie studied Physics in Mainz. For her bachelor thesis she investigated the influence of high-frequency magnetic fields on domain walls in ring structures on a micrometer length scale in the Kläui Group at the Institute of 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 Prof. Dirk schneider from 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.

In Sptember 2020 she disappeared to play with fancy Jupiter and Cypher AFMs started working for Asylum Research/Oxford Instruments as an application scientist.


Franjo Weber

Franjo Weber

Franjo does his Master thesis on nanoscale effects in battery materials jointly in the Weber and the Berger group. He is famous for his sandpaper skills will be known as the inventor of the KP-BS mode (the "BS" stands for bias spectroscopy, of course...).

Franjo can leave a lasting impression on locals through his absolute ignorance of soccer in general and Mainz 05 in particular.

In memoriam

Eduard Unger 1988 - 2018

Eduard Unger

On December 14th 2018, Eduard Unger died suddenly and unexpectedly.

Eduard studied Material Science at the University of Göttingen. During his master thesis he investigated the Planar-Hall-Effect and the Anisotropic Magneto Resistance in micro structured LaSrMnO3 thin films. For his PhD he moved to Mainz to investigate the role of defects in graphene on the THz conductivity under the joint supervision of Stefan and Dmitry Turchinovich at the MPI-P.

Eduard about himself: "He is feared for his mental confusion induced by lack of food. Don’t rely on any statements he makes during this period." This is how we will remember him - a great guy with a great sense of humour.

We all miss you.

Former members

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.