Temperature-Dependent Chirality in Halide Perovskites
Abstract
With the use of chiral organic cations in two-dimensional metal halide perovskites, chirality can be induced in the metal halide layers, which results in semiconductors with intriguing chiral optical and spin-selective transport properties. The chiral properties strongly depend upon the temperature, despite the basic crystal symmetry not changing fundamentally. We identify a set of descriptors that characterize the chirality of metal halide perovskites such as MBA$_{2}$PbI$_{4}$, and study their temperature dependence using molecular dynamics simulations with on-the-fly machine-learning force fields obtained from density functional theory calculations. We find that, whereas the arrangement of organic cations remains chiral upon increasing the temperature, the inorganic framework loses this property more rapidly. We ascribe this to the breaking of hydrogen bonds that link the organic with the inorganic substructures, which leads to a loss of chirality transfer.
AI-Generated Overview
Here's a brief overview of the scientific paper "Temperature-Dependent Chirality in Halide Perovskites," captured in bullet points focusing on key aspects of the research:
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Research Focus: Investigate the temperature-dependent chirality of two-dimensional (2D) metal halide perovskites, particularly how chiral organic cations influence the optical and spin-selective transport properties within these materials.
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Methodology: Utilize molecular dynamics simulations with on-the-fly machine-learning force fields, grounded in density functional theory (DFT) calculations, to analyze the structural descriptors that characterize chirality in the 2D perovskite model (S-MBA)2PbI4 across various temperatures.
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Results: Find that the chirality in the arrangement of organic cations is maintained at elevated temperatures, whereas the chirality of the inorganic framework diminishes significantly due to the breaking of hydrogen bonds, leading to a loss of chirality transfer from the cation to the framework.
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Key Contribution(s): Introduce a comprehensive set of structural descriptors for characterizing chirality in 2D halide perovskites, clarifying the distinct contributions of organic cation arrangements, inorganic framework chirality, and hydrogen bond asymmetry.
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Significance: The findings enhance understanding of chirality transfer mechanisms between organic and inorganic components at finite temperatures, which is crucial for optimizing the chiral properties of materials in optoelectronic applications.
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Broader Applications: The insights from this research can inform the design of advanced materials for solar cells, LEDs, and photodetectors by leveraging the exceptional chiral properties of halide perovskites, ultimately leading to enhanced performance in various optoelectronic devices.