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Thermal expansion (TE) behavior in solid-state materials is influenced by both molecular and supramolecular structure. For solid-state materials assembled through covalent bonds, such as carbon allotropes, solids with higher dimensionality (i.e., diamond) exhibit less TE than solids with lower dimensionality (e.g., fullerene, graphite). Thus, as the dimensionality of the solid increases, the TE decreases. However, an analogous and systematic variation of the dimensionality in solid-state materials assembled through noncovalent bonds with a correlation to TE has not been studied. Here, we designed a series of solids based on dimensional hierarchy to afford materials with zero-dimensional (0D), 1D, and 2D hydrogen-bonded structures. The 2D materials are structural analogues of graphite and covalent-organic frameworks, and we demonstrate that these 2D solids exhibit unique biaxial zero TE with anisotropic and colossal TE along the π-stacked direction (α ∼ 200 MK–1). The overall behavior in the 2D hydrogen-bonded solids is similar to 2D covalent-bonded solids; however, the coefficient of TE along the π-stacked direction for these hydrogen-bonded solids is an order of magnitude higher than in 2D graphite or phosphorus allotropes. The hierarchal materials design strategy and correlation to TE properties described herein can be broadly applied to the design and synthesis of new solid-state materials sustained by covalent or noncovalent bonds with control over solid-state behaviors.
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Non-covalent interactions involving π effect between organic cations in low-dimensional organic/inorganic hybrid perovskites
Low-dimensional organic/inorganic hybrid perovskites (OIHPs) are a promising class of materials with a wide range of potential applications in optoelectronics and other fields since these materials can synergistically combine individual features of organic molecules and inorganics into unique properties. Non-covalent interactions are commonly observed in OIHPs, in particular, π-effect interactions between the organic cations. Such non-covalent interactions can significantly influence important properties of the low-dimensional OIHPs, including dielectric confinement, bandgap, photoluminescence, quantum efficiency, charge mobility, trap density, stability, and chirality. This perspective reviews recent studies of non-covalent interactions involving the π systems of organic cations in low-dimensional OIHPs. The analysis of crystal structures of low-dimensional OIHPs offers significant insight into understanding such non-covalent interactions and their impacts on specific properties of these OIHPs. The developed structure–property relationships can be used to engineer non-covalent interactions in low-dimensional OIHPs for applications.
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- Award ID(s):
- 2154791
- PAR ID:
- 10436213
- Date Published:
- Journal Name:
- Applied Physics Letters
- Volume:
- 122
- Issue:
- 24
- ISSN:
- 0003-6951
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1063/5.0148876
