Disentangling Ion Migration from Artifacts in High-Fidelity ToF-SIMS Depth Profiling of Perovskite Solar Cells

Nico Fransaert^a, Jean Manca^a, Shabnam Ahadzadeh^b^,^c^,^d^,^e, Bart Ruttens^c^,^d, Jan D’Haen^c^,^d, Dirk Valkenborg^f, Bart Cleuren^g, Bart Vermang^c^,^d^,^e^,^h, Aslihan H. Babayigit^c^,^d^,^e^,^h

^aX-LAB, Department of Physics, Faculty of Sciences, UHasselt, B-3590 Diepenbeek, Belgium

^bFunctional Materials Engineering, Department of Engineering Materials and Applications, Faculty of Engineering Technology, UHasselt, B-3590 Diepenbeek, Belgium

^cInstitute for Materials Research (IUMAT), UHasselt, B-3500 Hasselt, Belgium

^dimec, IUMAT, B-3590 Diepenbeek, Belgium

^eEnergyVille, IUMAT, B-3600 Genk, Belgium

^fCenter for Statistics, Data Science Institute, Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Faculty of Sciences, UHasselt, B-3590 Diepenbeek, Belgium

^gTheory Lab, Department of Physics, Faculty of Sciences, UHasselt, B-3590 Diepenbeek, Belgium

^hPhotovoltaic Technology and Energy Systems Research, Department of Engineering Materials and Applications, Faculty of Engineering Technology, UHasselt, B-3600 Genk, Belgium

Proceedings of MATSUS Fall 2026 Conference (MATSUSFall26)

D2 Functional Materials for Emerging Photovoltaics: from Everyday Integration to Extreme Environments

Palma, Spain, 2026 October 26th - 30th

Organizers: Jessica Barichello, Stefania Cacovich and Fabio Matteocci

Invited Speaker, Aslihan H. Babayigit, presentation 415
Publication date: 22nd July 2026

In 2025, approximately 18% of Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) publications addressed perovskite (PVK) solar cells—nearly a threefold increase since 2020—highlighting the technique’s rapidly growing relevance.[1] Owing to its high chemical specificity and ability to probe buried interfaces without invasive sample preparation[2], ToF-SIMS is increasingly used to investigate ion migration, interfacial modification, additive passivation and degradation pathways that can be linked to changes in corresponding devices’ parameters. However, we show that ToF-SIMS data acquired from multilayered PVK solar cells cannot be interpreted analogously to its thin films.[3,4] Here, we establish a rigorously validated ToF-SIMS methodology that disentangles true ion migration from artifact-induced signals, revealing widely underappreciated measurement artifacts. Through systematic comparison of thin films and full devices based on archetypal MAPbI3 (1.6 eV) and compositionally complex (FA75Cs25)(Pb60Sn40)I3 (1.25 eV), we demonstrate that spurious ion gradients arise exclusively in multilayer stacks and originate from top-layer interactions. A controlled peeling protocol confirms their measurement-induced nature. We further introduce a fluence-matched acquisition protocol and a statistically grounded replicate-based workflow, revealing that single-profile measurements can yield contradictory interpretations, particularly for subtle interfacial phenomena (i.e. trace passivation). Applying this framework, we enable reliable analysis of pristine and aged buried self-assembled monolayers (SAMs), whose ultrathin (~1 nm) localized nature presents unique analytical challenges and growing importance in the design of molecular transport layers for high-efficiency, stable devices. Together, these results establish an artifact-aware, reproducible framework for high-fidelity ToF-SIMS depth profiling in PVK solar cells, providing a reference standard for reliable chemical analysis of complex multilayer semiconductors and their devices. As such, this work advances best practices in nanoscale characterization and in doing so supports precision interface engineering across next-generation energy technologies and beyond.

References:

[1] Web of Science, research paper publication statistics, keywords: ‘ToF-SIMS’ and ‘perovskites’, year: 2019-2024, retrieved on 19th February 2026.

[2] Rothmann, M. U., Li, W., Zhu, Y., Liu, A., Ku, Z., Bach, U., Etheridge, J. and Cheng, Y. B., 2018, Advanced Materials, 30(25), 1800629.

[3] Noël, C., Pescetelli, S., Agresti, A., Franquet, A., Spampinato, V., Felten, A., di Carlo, A., Houssiau, L. and Busby, Y., 2019, Materials, 12(5), 726.

[4] Harvey, S. P., Zhang, F., Palmstrom, A., Luther, J. M., Zhu, K. and Berry, J. J., 2019, ACS applied materials & interfaces, 11(34), 30911-30918.

Acknowledgements:

N.F. and J.V.M. thank Dr Alexis Franquet for overseeing the maintenance of the ToF-SIMS equipment at imec (Leuven, Belgium), which facilitated our measurements through the HERCULES ToF-SIMS collaboration 2022-2025 (imec/UHasselt). N.F. and A.H.B. thank Gabriel Belchior Miranda for insightful discussions. This research was carried out under financial support by Research Foundation – Flanders (FWO) under mandate grant IDs 11K4324N, 1260022N, 1SA4523N and 1297525N, and financial support by BOF-UHasselt grant ID R-12384.

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