Nanostructuring of Hybrid Halide Perovskites Down to stable Low-Dimensional and Semi-Metallic Allotropes: An ab initio study

Based on density functional theory (DFT) calculations, we studied the nanostructuring of the recently synthesized organic-inorganic trimethylsulfonium lead triiodide (CH₃)₃SPbI₃ perovskite, which showed a high ambient stability and an optical bandgap that extends into the visible range. We find that the two-dimensional (2D) monolayer and one-dimensional (1D) nanowire structures derived from three-dimensional (3D) (CH₃)₃SPbI₃ perovskite are energetically and dynamically stable. Furthermore, it is found that the inorganic 1D face-sharing PbI₆ framework prepared by removal of ligands is also structurally stable. Comparison of the electronic band structures of the 3D, 2D and 1D (CH₃)₃SPbI₃ allotropes shows that the band edge-region electronic structures are robustly determined at the 1D level. Most interestingly, we find that the 1D PbI₆ becomes semi-metallic, showing the possibility of deriving structurally and electronically diverse stable nanomaterials based on the parental 1D (CH₃)₃SPbI₃ component. We propose that these (CH₃)₃SPbI₃– and PbI₆–derived 2D and 1D hybrid perovaskites are promising candidates to be combined with other 2D materials such as transition metal dichalcogenides to achieve novel vertical heterosturctures for advanced electronic and optoelectronic applications.