Interplay of B-Site Off-Centering and Molecular Orientations in the Mixed Hybrid Perovskite MAGe1– x Sn x I3
Year: 2026
Type: article
Abstract: B-site mixing is a common strategy for tuning properties of halide perovskites. In the lead-free system MAGe1–xSnxI3, it brings tilting and off-centering into competition. Using large-scale molecular dynamics driven by a machine-learned interatomic potential, we map the structural behavior across the full composition range. MAGeI3 exhibits strong polar B-site off-centering that remains nearly constant up to the cubic transition, together with methylammonium (MA) orientational order that weakens progressively on heating. By contrast, MASnI3 combines octahedral tilting with weaker, predominantly antipolar off-centering. Ge-like behavior persists upon alloying and gives way to Sn-like behavior only beyond roughly 65% Sn. In the high-temperature phases, the B-site cations remain locally off-centered but directionally disordered. On the Ge-rich side, the distorted inorganic framework biases the soft MA orientational landscape toward a restricted set of preferred directions. This coupling shows how the composition of the inorganic sublattice can tune molecular ordering in lead-free hybrid perovskites.
Institution: Chalmers University of Technology
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
Funders: Stiftelsen för Strategisk Forskning, National Science Council, Knut och Alice Wallenbergs Stiftelse, Vetenskapsrådet, Energimyndigheten, Nanoscience and Nanotechnology Area of Advance, Chalmers Tekniska Högskola, Stiftelsen för Strategisk Forskning, European Research Council, HORIZON EUROPE European Research Council
Awards: G1135830669, Atomistic Design of Photoabsorbing Materials, G1579686824, G1920032164, GlaDys – Glass dynamics at ab-initio accuracy via gen-AI, Harnessing Localized Charges for Advancing Polar Materials Engineering, G2527441826, G3305595631, Analysis and Modelling Service for Engineering Materials Studied with Neutrons, G3391484441, G3676281905, G4010025062, G4350395237, G4632909464, G5404377299, Phase behavior and electronic properties of mixed halide perovskites from atomic scale simulations, Neutron scattering studies of dynamics in 2D hybrid halide perovskites -- on and off light illumination, G6539064727, Kvantmekanisk Beskrivning av Fullständiga Halvledaranordning, G712881263, G7448306189, G8742953867, NAISS, G978999556
OpenAlex ID: W7216291187