Dresden 2026 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 4: Perovskite and Photovoltaics: Synthesis and Performance
HL 4.6: Talk
Monday, March 9, 2026, 11:15–11:30, POT/0251
How stable are mixed-metal chalcohalides? — •Pascal Henkel1, Jarno Laakso1, Jingrui Li2, and Patrick Rinke1,3 — 1Department of Applied Physics, Aalto University, Espoo, Finland — 2Xi’an Jiaotong University, Xi’an, China — 3Technical University of Munich, Garching, Germany
Perovskite-inspired quaternary mixed-metal chalcohalides (MMCHs, M(II)2M(III)Ch2X3) are an emerging materials class for photovoltaics,[1,2] capable of delivering high conversion efficiencies.[3] Yet, their thermodynamic stability remains largely unexplored.
We assess the thermodynamic stability of 54 MMCH compounds by modelling their phase diagrams using DFT, pymatgen tools from Materials Project[4] and the Alexandria Materials Database.[5] All studied MMCHs lie above the convex hull, independent of their space group (Cmcm, Cmc21, P21/c). Accounting for computational uncertainty (mostly from the applied exchange-correlation functional) moves a considerable fraction of MMCHs close to or below the hull. The MMCH decomposition paths follow five reactions, with 4 M(II)2M(III)Ch2X3 ↔ 2 M(III)2Ch3 + 6 M(II)X2 + 2 M(II)Ch occurring most frequently. Experiments show that compounds close to the convex hull can be synthesized, whereas compounds far from the hull decompose following the predicted reactions. Overall, our results show that MMCHs are synthesizable, but fabrication conditions need further optimisation.
[1] Chem. Mater. 35, 7761-7769 (2023), [2] Phys. Rev. Materials 9, 115405 (2025), [3] Mater. Horiz. 8, 2709 (2021). [4] Chem. Mater. 20, 1798-1807 (2008). [5] https://alexandria.icams.rub.de/.
Keywords: perovskite-inspired materials; mixed-metal chalcohalides M(II)2M(III)Ch2X3; density functional theory; phase diagram; rietveld refinement