A morphotropic phase boundary in MA_1-xFA_xPbI₃: linking structure, dynamics, and electronic properties.

ABSTRACT: Understanding the phase behavior of mixed-cation halide perovskites is critical for optimizing their structural stability and optoelectronic performance. Here, we map the phase diagram of MA_1-xFA_xPbI₃ using a machine-learned interatomic potential in molecular dynamics simulations. We identify a morphotropic phase boundary (MPB) at approximately 27% FA content, delineating the transition between out-of-phase and in-phase octahedral tilt patterns. Phonon mode projections reveal that this transition coincides with a mode crossover composition, where the free energy landscapes of the M and R phonon modes become nearly degenerate. This results in nanoscale layered structures with alternating tilt patterns, suggesting minimal interface energy between competing ph

SUBMITTER: Hainer T 

PROVIDER: S-EPMC12491417 | biostudies-literature | 2025 Oct

REPOSITORIES: biostudies-literature