Ferroelasticity Mediated Energy Conversion in Strained Perovskite Films

Abstract

Metal halide perovskites (MHPs) have been shown to be key materials for next‐generation photovoltaic energy harvesting, electro‐optic detection, and all‐optical conversion. Room‐temperature tetragonal MAPbI3 has been reported to possess two space groups: polar I4cm and non‐polar I4/mcm. Although the space group of MAPbI3 is still under debate, significant effort has been expended to prove that I4cm MHPs are ferroelectric and I4/mcm MHPs are antiferroelectric. Both structures belong to the ferroelastic point group, and there has been debate regarding whether the domain structures observed on MHPs are ferroelectric or ferroelastic. The relationship between the ferroelectricity and ferroelasticity of MHPs has been discussed, whereas these two properties sometimes are regarded as mutually exclusive in MHPs. In this work, the ferroelectricity and ferroelasticity of MHPs originating from structural symmetry have been reviewed, and the interrelationship between the ferroelectricity and ferroelasticity of MHPs are discussed.

In-situ Optical Control of Local Periodical Ferroelastic Domain Evolution in CH3NH3PbI3 Perovskites

“…The domains could be ferroelastic twins developed in the MAPbI 3 cubic−tetragonal transition to minimize the strain energy in the system. 15,29,32 To understand the ferroelastic domain dynamic behaviors of MAPbI 3 crystal in response to the optical fields, we select a pulsed infrared laser at 1468 cm −1 to irradiate the crystal. The 1468 cm −1 IR illumination corresponds to the C−N stretching vibration mode of MA + in the MAPbI 3 crystal structure 37 and also represents the CH 3 asymmetric deformation of the methylammonium ion, which is expected to induce lattice strain and the resulting optical control of local ferroelastic domain evolution.…”

“…Thus, the dynamics in Figures 3 and 4 segregation due to the strains. 15,32,34 Since the strain orientation is determined by the crystallographic order, periodically ferroelastic domain stripes can be visible in the chemical map.…”

“…Thus, the dynamics in Figures and give us a unique insight into local nucleation and growth dynamic process of CH 3 NH 3 PbI 3 perovskites under the IR illumination. Such optical control of ferroelastic domains evolution is fundamentally related to the interaction of C–N chemical bond with 1468 cm –1 IR, which induces the CH 3 NH 3 + rotation, the crystal structure distortion, and thus the CH 3 NH 3 + segregation due to the strains. ,, Since the strain orientation is determined by the crystallographic order, periodically ferroelastic domain stripes can be visible in the chemical map.…”

Introducing Ferroelasticity into 1D Hybrid Lead Halide Semiconductor by Halogen Substitution Strategy

“…[16][17][18][19][20][21] Recently, ferroelastic domain walls are benign to the charge carrier transport in OLHPs is reported and therefore, introducing ferroelasticity into OLHPs is fascinating for enhancing their properties. [22][23][24][25][26] However, there are still few 1D OLHPs with outstanding ferroelasticity that are so far reported.…”

Nanoscale Thermal Strain Engineering-Driven Ferroelastic Domain Evolution in CH3NH3PbI3 Perovskites

“…Metal halide perovskites (MHPs) have been paid significant attention due to their most promising applications in next-generation solar cells. − The power conversion efficiency of MHP solar cells has been increased from the initial 3.9% in 2009 to 25.7% in 2022. , Such a unique performance is closely involved with their microstructures and the corresponding dynamics in response to external fields. − For tetragonal methylammonium lead triiodide perovskites (MAPbI 3 ) at room temperature, their ferroic microstructures have been considered to be ferroelectric domains, − ferroelastic domains, ,, and domains with alternating polar and non-polar orders in recent studies. , These interesting features reveal the microstructural complexities in the MAPbI 3 system. In view of space group of tetragonal MAPbI 3 at room temperature, both the proposed polar I 4 cm or non-polar I 4/ mcm group could give rise to ferroelastic domains with 0, 45, and 90° domain walls for MAPI 3 crystals and predominant 70 and 90° walls for MAPbI 3 thin films .…”