Like Molybdenum Disulfide (MoS2), Tungsten Disulfide (WS2) is a member of the family of materials known as transition metal dichalcogenides (TMDs). These materials are much like graphene in their nature, being 2-D materials that have properties differing significantly from those of their bulk properties. Thanks to its unique properties, WS2 is currently one of the most studied TMDs in literature.
At Ossila we sell a range of tungsten disulfide (WS2) products, including powders for depositing monolayer and multilayers. In addition, we offer pre-made solutions of these powders for quick and easy deposition.
What is Tungsten Disulfide?
Tungsten disulfide (WS2) in bulk has been used for many years as a dry lubricant due to how it exhibits similar properties to Molybdenum Disulfide (MoS2), such as a low coefficient of friction, high chemical stability, and thermal stability. In 1992, it was discovered that the structure of WS2 made it capable of forming nanotube structures. These nanotubes were the first examples of WS2 being used as a low-dimensional material.
After the discovery of simple mechanical exfoliation techniques to isolate single layers of 2-D materials, it was possible to study the properties of WS2 flakes. It was shown that, just like MoS2, the band-gap of WS2 change from an indirect band-gap of 1.4eV to a direct band-gap of 2eV when changing from a bulk material to a 2-D material. Due to its band-gap, WS2 is seen as a significantly interesting material for many areas of application.
Just like MoS2, WS2 possesses a high on/off ratio in field-effect transistors, controllable spin and valley polarisation, strong geometrical confinement of excitons, and tunable photoluminescence. Additionally, WS2 could lead to increased interest in areas such as photodetectors and multi-junction photovoltaics.
At Ossila we have a range of Tungsten Disulfide powders for sale, including monolayer Tungsten Disulfide, WS2 (M841), and multi-layer WS2 (M851). These materials come packed as dry powders that are ready for re-dispersion within your solvent of choice. In addition, we sell pre-made solutions using M841 and M851 and concentrations of 1 mg.ml-1 and 0.1 mg.ml-1.
Tungsten Disulfide Powders
|Flake Size||0.1-4 μm||~0.2-10 μm|
|Flake Thickness||0.6-1.2 nm||0.6 - 6 nm|
|Single layer ratio||95%||N/A|
|Packaging Information||Light-resistant bottle||Light-resistant bottle|
Tungsten Disulfide Solutions
|Solution Volume||100 ml||100 ml||100 ml||100 ml|
|Concentration||1 mg.ml-1||0.1 mg.ml-1||1 mg.ml-1||0.11 mg.ml-1|
|Packaging Information||4 x 25 ml Bottles||4 x 25 ml Bottles||4 x 25 ml Bottles||4 x 25 ml Bottles|
Tungsten disulfide readily goes into dispersion in a range of different polar solvents. At Ossila, we have found that the most stable dispersion for mono-layers and multi-layers can be produced using the following recipe:
- Weigh out desired amount of material (this can go up to 1 mg.ml-1)
- Add 1:1 ratio of ethanol to deionized water
- Shake vigorously to break up material
- A 2 hour treatment in an ultrasonic bath will homogeneously disperse the material (40 kHz, 100 W ultrasonic bath)
|HOMO/LUMO||HOMO = 5.82 eV; LUMO = 3.84 eV|
|Bandgap||Eg = 1.98 eV (low dimensional bandgap), Eg = 1.4eV (bulk bandgap)|
|Recommended Solvents||H2O, NMP, Ethanol, IPA|
|Classification / Family||2D semiconducting materials, Monolayer materials, Thin-layered transition-metal dichalcogenides (TMDs), N-type semiconductors|
- Electrically Tunable Valley-Light Emitting Diode (vLED) Based on CVD-Grown Monolayer WS2, W. Yang et al., Nano Lett., 16 (3), 1560–1567 (2016); DOI: 10.1021/acs.nanolett.5b04066
- Synthesis and Transfer of Large-Area Monolayer WS2 Crystals: Moving Toward the Recyclable Use of Sapphire Substrates, Z. Xu et al., ACS Nano, 9(6), 6178-6187 (2015); DOI: 10.1021/acsnano.5b01480.
- Light Generation and Harvesting in a van der Waals Heterostructure, O. Lopez-Sanchez et al., ACS Nano, 8 (3), 3042–3048 (2014); DOI: 10.1021/nn500480u.
- Chemically Driven Tunable Light Emission of Charged and Neutral Excitons in Monolayer WS2, N. Peimyoo et al., ACS Nano, 8 (11), 11320–11329 (2014); DOI: 10.1021/nn504196n
- Exciton and charge carrier dynamics in few-layer WS2, V. Vega-Mayoral et al., Nanoscale, 8, 5428 (2016); DOI: 10.1039/c5nr08384b.
- Identification of individual and few layers of WS2 using Raman Spectroscopy, A. Berkdemir et al., Sci. Rep., 3, 1755 (2013); doi:10.1038/srep01755.
- Direct Observation of Degenerate Two-Photon Absorption and Its Saturation in WS2 and MoS2 Monolayer and Few-Layer Films, S. Zhang et al., ACS Nano, 9 (7), 7142–7150 (2015); DOI: 10.1021/acsnano.5b03480.
- Layered semiconductortungsten disulfide: photoactive material in bulk heterojunction solar cells, M. Shanmugam et al., Nano Energy 2, 419–424 (2013); http://dx.doi.org/10.1016/j.nanoen.2012.11.011.
Graphene and 2D Related Products
To the best of our knowledge, the technical information provided here is accurate. However, Ossila assume no liability for the accuracy of this information. The values provided here are typical at the time of manufacture and may vary over time and from batch to batch.