Sustainable Energy Materials

Hybrid Solar Cells

Led by
Bruno Ehrler

The Hybrid Solar Cell Group investigates the next generation of solar cells using metal halide perovskites. By deeply understanding the unique material properties and their impact on device performance, we aim to improve the stability of perovskite solar cells and develop new brain-inspired devices.

Research focus

The Hybrid Solar Cell Group researches the next generation of solar cells using metal halide perovskites. We develop a deep understanding of material properties and their impact on device performance. 

Our focus is on improving the stability of perovskite solar cells, addressing ion migration as a key challenge. We have developed unique techniques to study and suppress ion migration and explore new applications for ion migration. On the one hand, suppressing ion migration leads to more stable solar cells. At the same time, combining the excellent semiconducting properties of perovskites with mobile ions, we develop devices for memory applications. 

Perovskite solar cells have caused a huge surge of interest recently due to their high efficiency, now approaching that of crystalline silicon. Stunningly, these materials are made of cheap and abundant ingredients and are solution-processable. 

Despite the rapid progress in solar cell efficiency, many of the more fundamental properties are not well understood. To make further progress in materials design, in particular to reduce toxicity and increase lifetime, we need to fully understand these materials. 

We work towards a better understanding of the working principles of hybrid perovskite semiconductors and devices, using a combination of spectroscopic methods and device design. Our focus lies on a unique property that characterizes perovskites, namely ion migration. 


Perovskite structure
Image of a perovskite crystal structure showing how the atoms are arranged. The purple and yellow octahedra represent groups of charged atoms, ions, built around a lead atom in the center.

Perovskite semiconductors are efficient conductors for electrons and ions. For solar cells and LEDs we need to carefully control the ion migration to ensure long-term stability. On the contrary, ion migration can be used to imprint memory in a device for energy-efficient computation.

Our group specializes in novel methods to characterize mobile ions, combining electrical spectroscopy, correlative microscopy, and simulations.

With that knowledge, we develop strategies toward more stable perovskite solar cells, and we fabricate artificial synapses and neurons with this mechanism to enable hardware neural networks.

Researchers and Staff
Group members
Bruno Ehrler
Bruno Ehrler
Group leader

Most recent publications

Microscale Optoelectronic Synapses with Switchable Photocurrent from Halide Perovskite
de Boer, J., Alvarez, A., Schmidt, M., Sitaridis, D.& Ehrler, B. (2026). Microscale Optoelectronic Synapses with Switchable Photocurrent from Halide Perovskite. ACS Appl. Electron. Mater., 8(9), 3804–3813.https://doi.org/10.1021/acsaelm.5c02469
Polycarbazole–NiOOH Interfacial Engineering of BiVO4 Photoanodes for Efficient and Stable Solar Water Splitting
Arumugam, L. S., Gutierrez‐Blanco, A., Alvarez, A., Saura Aviles, A., Eledath‐Changarath, M., Abargues, R., Sánchez‐Royo, J. F., Rabelo, H., Spadaro, M. C., Arbiol, J., Durantini, J.& Giménez, S. (2026). Polycarbazole–NiOOH Interfacial Engineering of BiVO4 Photoanodes for Efficient and Stable Solar Water Splitting. Energy Environ. Mater., e70354: 1–11.https://doi.org/10.1002/eem2.70354
First-Day Degradation and Night-Time Recovery Mechanisms of Lead–Tin Perovskite Solar Cells
Dekker, D., Alvarez, A., Schmidt, M., Chen, L., Garcia Romero, D., Pitaro, M., Feng, Q., Loi, M. A.& Ehrler, B. (2026). First-Day Degradation and Night-Time Recovery Mechanisms of Lead–Tin Perovskite Solar Cells. J. Phys. Chem. Lett., 17(13), 3796–3804.https://doi.org/10.1021/acs.jpclett.6c00065
Photoluminescence Mapping of Mobile and Fixed Defects in Halide Perovskite Films
Gillespie, S., Gautier, J., van de Ven, L., Alvarez, A., Ehrler, B., Geerlings, B., Gevaerts, V., Coletti, G.& Garnett, E. (2026). Photoluminescence Mapping of Mobile and Fixed Defects in Halide Perovskite Films. ACS Energy Lett., 11(4), 3330–3339.https://doi.org/10.1021/acsenergylett.5c04253
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