Congratulations to Dr.-Ing. Marina Günthert on her outstanding PhD defence!
We warmly congratulate Dr.-Ing. Marina Günthert, who successfully defended her doctoral thesis on 11 May 2026 and completed her doctorate with the highest possible distinction.
Her dissertation, Simulation and Characterization of Lead-Free Double Perovskites, was jointly supervised by Prof. Christoph Brabec and Prof. Meyer and brought together expertise in photovoltaics, materials science and computational chemistry.
Lead-based perovskites have emerged as promising materials for next-generation solar cells, but concerns over toxicity continue to motivate the search for safer alternatives. Marina focused on lead-free double perovskites — a chemically diverse class of materials whose properties can be tuned by varying the elements and their relative proportions within the crystal structure.
The aim of her work was to determine which combinations could form a “well-behaved semiconductor”: a material that is stable, based on abundant and non-toxic elements, and possesses a suitable bandgap and charge-carrier mobility for photovoltaic applications.
To explore this large compositional space, Marina combined high-throughput density functional theory calculations with experimental knowledge, statistical correlation analysis and machine-learning algorithms. An initial study of 81 compounds from the CANBIC double-perovskite family demonstrated how computational and experimental datasets could be integrated to rapidly pre-screen potential photovoltaic materials.
She subsequently extended the approach from medium-entropy to high-entropy systems, in which several elements share the same crystallographic sites. The results revealed complex, non-linear relationships between chemical composition and optoelectronic properties.
Because published datasets on lead-free double perovskites remain incomplete and strongly biased towards a limited number of compositions, Marina also created an in-house computational database. This enabled her to assess which elements were most promising for different positions in the double-perovskite structure, considering both energetic stability and stabilization through configurational entropy.
An iterative random-sampling strategy was then used to investigate high-entropy compositions containing as many as 20 different elements. From a dataset of 172 calculated compositions, predictive models identified new candidates with reduced bandgaps and lower effective charge-carrier masses. Chemical constraints were incorporated into the analysis to estimate whether the predicted materials could realistically be synthesized.
The findings suggest that increasing compositional entropy can improve key optoelectronic properties and provide new routes towards the inverse design of lead-free semiconductor materials. The work also demonstrates the value of combining advanced computational methods with chemical domain knowledge and the principles of green chemistry.
Marina studied Molecular Science at FAU, completing both her bachelor’s and master’s degrees. She began working on photovoltaic materials during her bachelor’s thesis in the Bachmann group and became associated with HI ERN during her master’s studies. She started her doctoral research in January 2023 and submitted her dissertation in December 2025.
Since March 2026, she has been working as a Materials Scientist in industrial research at Siemens Energy. We congratulate Dr.-Ing. Marina Günthert on this outstanding achievement and wish her continued success in her scientific career!
