We reveal a spectrum of potentially exfolaible 1D wires and characterize their electronic properties

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Two-dimensional (2D) materials derived from van der Waals (vdW)-bonded layered crystals have been the subject of considerable research focus, but their one-dimensional (1D) analogues have received less attention. These bulk crystals consist of covalently bonded multi-atom atomic chains with weak van der Waals bonds between adjacent chains.


Figure 1. Decomposition of sample geometry HfI3 into separate 1D wires (wire axis pointing into the page). For the structures studied, the bonds between adjacent wires are primarily van der Waals in nature, while the bonds within a single wire are primarily ionic or covalent in character.

Using density-functional-theory-based methods, we find the binding energies of several 1D families of materials to be within typical exfoliation ranges possible for 2D materials. We compute the electronic properties of a variety of insulating, semiconducting, and metallic individual wires and find differences that could enable the identification of and distinction between 1D, 2D, and 3D forms during mechanical exfoliation onto a substrate.


Figure 2. The binding energy required for extracting a 2D plane of wires from the bulk can be compared to the binding energy required to extract a 1D wire from the bulk per formula unit. The energies to extract 2D layers composed of 1D wires are comparable to the energies of known exfoliable 2D layered materials when compared by surface area (left). The bandstructure of the bulk structure and the separated 1D wire are shown for composition HfI3, indicating minimal changes in the band character (right).

Like 2D vdW materials, we find some of these 1D vdW materials have the potential to retain their bulk properties down to nearly atomic film thicknesses, including the structural families of HfI3 and PNF2, a useful property for some applications including electronic interconnects. We also study naturally occurring bulk crystalline heterostructures of 1D wires and identify two families that are likely to be exfoliable and identifiable as individual 1D wire subcomponents. DFT-MD simulations are performed to verify the stability of the individual 1D wire structures.

Contact: Yanbing Zhu, yanbingz_at_stanford.edu

Publication:

Zhu, Y., Rehn, D. A., Antoniuk, E. R., Cheon, G., Freitas, R., Krishnapriyan, A., and Reed, E. J. Spectrum of Exfoliable 1D van der Waals Molecular Wires and Their Electronic Properties ACS Nano 15, 6 (2021) doi.org/10.1021/acsnano.1c00781