Controlling Doping and Defect Activity Towards Photostable Tin-Halide Perovskites

Filippo De Angelis^a

^aComputational Laboratory for Hybrid and Organic Photovoltaics - Istituto CNR di Scienze e Tecnologie Chimiche (SCITEC-CNR) c/o Department of Chemistry, Biology and Biotechnologies, University of Perugia Via Elce di Sotto 8, 06123 Perugia, Italy

Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV26)

Uppsala, Sweden, 2026 May 18th - 20th

Organizers: Gerrit Boschloo, Ellen Moons, Feng Gao and Anders Hagfeldt

Invited Speaker Session, Filippo De Angelis, presentation 193
Publication date: 11th March 2026

Replacing lead by less toxic elements remains a major challenge for the widespread uptake of perovskite-based technologies. Tin appears the only candidate to replace lead, due to the accidentally similar structural and electronic properties of these two elements. A major difference, however, is the stability of Sn(IV) phases, which are related to the lower oxidation potential of tin compared to lead. A related phenomenon is the stability of tin vacancies, which introduce significant p-doping in tin-halide perovskites (THPs), while their lead-based counterpart are essentially intrinsic semiconductors. Defect activity clearly controls doping and could also contribute to the instability towards Sn(IV) phases. Controlling doping and defect activity thus represents a pathway towards obtaining stable THPs with optimal optoelectronic properties. The different defect activity of tin- and lead-based materials is at the origin of their respective thermal and phot-induced degradation phenomena, including halide demixing and loss of I₂ in lead-halide perovskites.

Here we present results of advanced modelling studies on the defect mediated degradation pathways of prototypical THPs. We show how Sn-vacancies are central in promoting both material p-doping and formation of Sn(IV) phases. Interestingly, while p-doping dominates in the bulk, Sn oxidation is only favoured at surfaces or grain boundaries. Thus achieving uniform thin films coupled with proper surface passivation strategies represent a pathway towards achieving more stable THP-based devices. Surprisingly, THPs have also received a large attention because of their superior stability in water environment compared to their lead counterparts. We further unveil the key factors determining the stability of mixed-halide THPs against photoinduced halide segregation phenomena. Molecular and ionic strategies to mitigate p-doping in THPs are also presented.

References

[1] Gatto, L.; Poli, I.; Meggiolaro, D.; Grandi, F.; Folpini, G.; Treglia, A.; Cinquanta, L.; Petrozza, A.; De Angelis, F.; Vozzi, C.; "Charge-Phonon Coupling in Tin Halide Perovskites", ACS Energy Lett. 2025, 10, 1382−1388

[2] Suo, J.; Yang B.; Mosconi, E.; Bogachuk, D.; Doherty, T.A.S.; Frohna, K.; Kubicki, D.J.; Fu, F.; Kim, Y.J.; Er-Raji, O.; Zhang, T.; Baldinelli, L.; Wagner, L.; Tiwari, A.N.; Gao, F.; Hinsch A.; Stranks, S.D.; [3] De Angelis, F.; Hagfeldt, A. "Multifunctional sulfonium-based treatment for perovskite solar cells with less than 1% efficiency loss over 4,500-h operational stability tests" Nat. Energy, 2024, 9, 172-183

Zhou Y.; Poli I.; Meggiolaro D.; De Angelis F.; Petrozza A. "Defect activity in metal halide perovskites with wide and narrow bandgap" Nat. Rev. Mater., 2021, 6, 986–1002

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