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Nanowires of layered van der Waals (vdW) crystals are of interest due to structural characteristics and emerging properties that have no equivalent in conventional 3D crystalline nanostructures. Here, vapor-liquid-solid growth, optoelectronics, and photonics of GaS vdW nanowires are studied. Electron microscopy and diffraction demonstrate the formation of high-quality layered nanostructures with different vdW layer orientation. GaS nanowires with vdW stacking perpendicular to the wire axis have ribbon-like morphologies with lengths up to 100 micrometers and uniform width. Wires with axial layer stacking show tapered morphologies and a corrugated surface due to twinning between successive few-layer GaS sheets. Layered GaS nanowires are excellent wide-bandgap optoelectronic materials with Eg = 2.65 eV determined by single-nanowire absorption measurements. Nanometer-scale spectroscopy on individual nanowires shows intense blue band-edge luminescence along with longer wavelength emissions due to transitions between gap states, and photonic properties such as interference of confined waveguide modes propagating within the nanowires. The combined results show promise for applications in electronics, optoelectronics and photonics, as well as photo- or electrocatalysis owing to a high density of reactive edge sites, and intercalation-type energy storage benefitting from facile access to the interlayer vdW gaps.
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Bonding-imposed crystallization of 1D nanostructures based on a luminescent and anisotropic 2D van der Waals crystal
Physical states in nanoscale solids are tied to their crystalline order, morphology, and size. However, deterministically accessing different nanocrystal morphologies from a single phase usually involves complex synthetic routes, catalysts, or multi-step lithographic techniques. Here, we demonstrate the catalyst-free synthesis of nanosheets and nanowires based on the luminescent 2D van der Waals (vdW) phase, GaTe, as a model phase that manifests atomic precision and a highly anisotropic quasi-1D substructure. We program the size and morphology of the resulting nanostructures by varying the relative rates of precursor deposition and diffusion, achieving dense, uniform, and widespread growth. Ultrathin nanowires resulting from this synthesis exhibit strikingly enhanced low-temperature luminescence with narrow near-infrared (NIR) emission bandwidths. These spectral characteristics arise from defect-bound states confined within a nanowire morphology that acts as a deep sub-wavelength optical cavity, making them suitable as optical emitters with small footprints either as stand-alone structures or coupled with other vdW crystals.
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- Award ID(s):
- 2340918
- PAR ID:
- 10657896
- Publisher / Repository:
- ChemRxiv
- Date Published:
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Posted Content:
- https://doi.org/10.26434/chemrxiv-2025-h1qbm
