Stabilizing Polar Domains in MAPbBr 3 via the Hydrostatic Pressure-Induced Liquid Crystal-like Transition
Pressure-induced phases of MAPbBr were investigated at room temperature in the range of 0-2.8 GPa by molecular dynamics. Two structural transitions at 0.7 GPa (cubic → cubic) and 1.1 GPa (cubic → tetragonal) involved both the inorganic host (lead bromide) and the organic guest (MA). MA dipoles behav...
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Published in | The journal of physical chemistry letters Vol. 14; no. 24; pp. 5497 - 5504 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
United States
22.06.2023
|
Online Access | Get full text |
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Summary: | Pressure-induced phases of MAPbBr
were investigated at room temperature in the range of 0-2.8 GPa by
molecular dynamics. Two structural transitions at 0.7 GPa (cubic → cubic) and 1.1 GPa (cubic → tetragonal) involved both the inorganic host (lead bromide) and the organic guest (MA). MA dipoles behave like a liquid crystal undergoing isotropic → isotropic and isotropic → oblate nematic transitions as pressure confines their orientational fluctuations to a crystal plane. Beyond 1.1 GPa, the MA ions lie alternately along two orthogonal directions in the plane forming stacks perpendicular to it. However, the molecular dipoles are statically disordered, leading to stable polar and antipolar MA domains in each stack. H-Bond interactions, which primarily mediate host-guest coupling, facilitate the static disordering of MA dipoles. Interestingly, high pressures suppress CH
torsional motion, emphasizing the role of C-H···Br bonds in the transitions. |
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ISSN: | 1948-7185 1948-7185 |
DOI: | 10.1021/acs.jpclett.3c01152 |