Impact of Metal Cation on Chiral Properties of 2D Halide Perovskites

Abstract

Chiral two-dimensional (2D) halide perovskites are formed by embedding chiral organic cations in a perovskite crystal structure. The chirality arises from distortions of the 2D metal halide layers induced by the packing of these organic cations. Sn-based octahedra spontaneously distort, but it remains unclear whether this intrinsic structural instability enhances the chirality. We investigate the effect of the metal cation on structural and phonon chirality in MBA${}_2$Sn${}_{\mathrm{x}}$Pb${}_{1-\mathrm{x}}$I${}_4$ (x = 0, 1/2, and 1). Incorporating Sn does distort the metal halide octehedra, yet it only has a minor impact on the structural chirality. In contrast, the phonons in MBA${}_2$SnI${}_4$ are substantially more chiral than in MBA${}_2$PbI${}_4$, especially the in-plane acoustic modes. However, this enhanced phonon chirality does not lead to a generation of a larger angular momentum under a temperature gradient, because the contributions of different chiral phonons tend to compensate one another.

19 pages, 6 figures

References in corpus (7)

• Implementation strategies in phonopy and phono3py
• Absolute energy level positions in tin and lead based halide perovskites
• On-the-fly machine learning force field generation: Application to melting points
• Phase transitions of hybrid perovskites simulated by machine-learning force fields trained on-the-fly with Bayesian inference
• Chiral Phonons in Chiral Materials
• Lone-Pair Stereochemistry Induces Ferroelectric Distortion and the Rashba Effect in Inorganic Halide Perovskites
• Temperature-Dependent Chirality in Halide Perovskites