Alfa Chemistry focuses on two-dimensional (2D) nanomaterials technology companies, mainly dealing with MXenes and MAX phase materials, black phosphorus, etc. Our R&D team is led by a group of PhDs with international study and years of research experience. We can "personalize" our WSe2 solutions to meet the needs of our customers. Please contact us today to assist you in solving your problem quickly.
Tungsten Diselenide (WSe2)
With a bandgap of 1.2 eV, WSe2 is an indirect bandgap semiconductor material with a high absorption coefficient, good photostability, and a high absorption coefficient. WSe2 nanosheets and particles are used in a variety of devices, including photodetectors, transistors, photovoltaic solar cells, and light-emitting diodes, as well as biomedical and photothermal treatments.
The tungsten atoms in the WSe2 monolayer are sandwiched between two layers of selenium atoms, each of which is linked to six selenium atoms by strong covalent ionic connections. Weak van der Waals forces stabilize the multilayer structure. These forces are strong enough to hold the layers together, but not so strong that mechanical exfoliation is possible. Mechanical or chemical exfoliation can be used to create monolayer and layerless WSe2 nanosheet structures and nanoparticles.
Fig 1. Exfoliated WSe2 flake with approximately 350 nm in lateral size. (Gerchman D, et al. 2016)
WSe2 Solution Synthesis and Characterization
Alfa Chemistry provides unique solutions with WSe2 flakes, which are widely utilized in the catalytic community. The solutions are created by ultrasonically sonicating high-quality bulkWSe2 crystals produced using CVT technology. Depending on your specifications. We can create single-layer, layer-less, multi-layer, and bulk-layer solutions. When requesting a quote, please decide the sort of solution you like to employ.
2D nanosheets with high structural quality and stable, uniformly dispersed flakes can be produced using ultrasound-assisted liquid phase exfoliation processes. However, the fundamental drawback of liquid-phase exfoliation is that WSe2 nanosheets re-stack into bulk structures due to van der Waals interactions, limiting its general application. To overcome these difficulties, we used adenine-capped polypropylene glycol (A-PPG) as a surfactant and stabilizer to aid the efficient liquid-phase exfoliation of WSe2 in tetrahydrofuran by sonication.
Fig 2. Chemical structure of A-PPG macromonomer and schematic diagram of non-covalent liquid phase exfoliation of WSe2 nanosheets in the presence of A-PPG dispersant. (Muhabie A, et al. 2018)
The sonication method for exfoliating WSe2 layers provides highly crystalline WSe2 monolayers, a few layers, and some thick layers suspended in solution because the starting material is highly crystalline. Photoluminescence is created in thin sheets placed on various substrates, depending on the thickness of the layer.
| Specifications |
|
|---|---|
| Identification | The WSe2 solution produced by layering the CVT method-grown WSe2 crystals by ultrasonic technology |
| Physical Sizes | 1 to 10 layers thick (thicker fragments may be observed depending on usage), 10 nm to 10 microns lateral dimension. |
| Purity | 99.999% |
| Smoothness | Atomically smooth surface with roughness < 0.35 nm. |
| Crystallinity | Highly crystalline nanomaterials. No amorphous flakes, contaminants or hidden second phases. |
| Dispersant solution | Ethanol, isopropanol, deionized water, NMP, other solvents can be prepared as needed. |
| Stability | High environmental and dispersant stability. |
| Support | We provide full technical support and guarantee your satisfaction with our renowned customers. |
| Characterization Methods | Raman, EDS, AFM, SEM; Contact us for more information |
Note
We ship supersaturated 2D solutions at concentrations of 80-120 mg/L (depending on the type of 2D layer) to reduce shipping costs. These supersaturated solutions can be diluted to make substantial volumes (250-500 mL) that can be used in a simple and cost-effective rotary casting method to deposit 2D layers onto the suitable substrate. Because of its environmental stability, thermal stability, dispersing characteristics, and non-polluting nature, ethanol is recommended as a dispersant solvent. Please contact us if your research necessitates the use of different solvents.
References
- Gerchman D, et al. (2016). "Solution-Processable Exfoliation and Suspension of Atomically Thin WSe2." Journal of Colloid and Interface Science. 468: 247-252.
- Hanlon D, et al. (2015). "Dynamic Tungsten Diselenide Nanomaterials: Supramolecular Assembly-Induced Structural Transition Over Exfoliated Two-Dimensional Nanosheets." Chem. Sci. 9: 5452-5460.
Please kindly note that our products are for research use only.
