Hybrid nano-domain structures of organic-inorganic perovskites from molecule-cage coupling effects

TL;DR

This study uses advanced molecular dynamics simulations to uncover spontaneous nano-domain behaviors in hybrid organic-inorganic perovskites, revealing how molecular and lattice interactions influence their structure and stability.

Contribution

First discovery of spontaneous nano-domain behavior in hybrid perovskites using DPMD simulations, clarifying diffraction patterns and structural characteristics.

Findings

Identification of multiple molecular rotation nano-domains within a single octahedral domain

Explanation of diffraction pattern puzzles at low temperatures

Insights into the structural stability of hybrid perovskites

Abstract

In hybrid perovskites, the organic molecules and inorganic frameworks exhibit distinct static and dynamic characteristics. Their coupling will lead to unprecedented phenomena, which have attracted wide research interests. In this paper, we employed Deep Potential molecular dynamics (DPMD), a large-scale MD simulation scheme with DFT accuracy, to study $\mathrm{FA/MAPbI_3}$ hybrid perovskites. A spontaneous hybrid nano-domain behavior, namely multiple molecular rotation nano-domains embedded into a single $\mathrm{[PbI_6]^{4-}}$ octahedra rotation domain, was firstly discovered at low temperatures. The behavior originates from the interplay between the long range order of molecular rotation and local lattice deformation, and clarifies the puzzling diffraction patterns of $\mathrm{FAPbI_3}$ at low temperatures. Our work provides new insights into the structural characteristics and stability of hybrid perovskite, as well as new ideas for the structural characterization of organic-inorganic coupled systems.