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In-plane Aligned Colloidal 2D WS2 Nanoflakes for Solution-Processable Thin Films with High Planar Conductivity
Rosanna Mastria1, Riccardo Scarfiello1, Davide Altamura2
1CNR NANOTEC - Institute of Nanotecnology, Polo di Nanotecnologia, c/o Campus Ecotekne, Via Monteroni snc, 73100, Lecce, Italy.
Scientific Reports
|June 23, 2019
Summary
Researchers developed a new method to create large-area thin films from tungsten disulfide (WS₂) nanocrystals. This process improves electrical conductivity and enables optoelectronic applications for two-dimensional transition-metal dichalcogenides (2D-TMDs).
Area of Science:
- Materials Science
- Nanotechnology
- Condensed Matter Physics
Background:
- Two-dimensional transition-metal dichalcogenides (2D-TMDs) are promising for advanced electronics and optoelectronics.
- Fabricating large-area, high-performance 2D-TMD thin films remains a challenge.
Purpose of the Study:
- To develop a cost-effective bottom-up approach for creating large-area 2D-TMD thin films.
- To enhance the electrical properties of tungsten disulfide (WS₂) thin films using colloidal nanocrystals.
Main Methods:
- Utilized ultrathin WS₂ colloidal nanocrystals with excellent solution stability.
- Employed a layer-by-layer deposition technique for millimetre-scale film assembly.
- Applied a room-temperature superacid surface treatment to remove insulating surfactants and heal sulfur vacancies.
Main Results:
- Achieved in-plane assembly of WS₂ nanoflakes parallel to the substrate.
- Demonstrated high planar conductivity (up to 1 μS) in the resulting WS₂ thin films, comparable to epitaxial monolayers.
- Observed photocurrent generation across visible to near-infrared frequencies.
Conclusions:
- A novel surface treatment enables the fabrication of high-quality WS₂ thin films from colloidal nanocrystals.
- The developed method offers a scalable and practical route for producing 2D-TMDs for electronic and optoelectronic devices.
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