Tungsten diselenide
| Tungsten diselenide | ||
|---|---|---|
 | ||
| Identifiers | ||
| CAS number | 12067-46-8 | |
| Properties | ||
| Molecular formula | Se2W | |
| Molar mass | 341.76 g/mol | |
| Appearance | grey | |
| Density | 9.32 g/mL | |
| Hazards | ||
| Main hazards | External MSDS | |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa) | ||
| Infobox references | ||
Tungsten diselenide is an inorganic compound with the formula WSe2.[1] The compound adopts a hexagonal crystalline structure similar to molybdenum disulfide. Every tungsten atom is covalently bonded to six selenium ligands in a trigonal prismatic coordination sphere while each selenium is bonded to three tungsten atoms in a pyramidal geometry. The tungsten – selenium bond has a bond distance of 2.526 Å and the distance between selenium atoms is 3.34 Å.[2] Layers stack together via van der Waals interactions. WSe2 is a very stable semiconductor in the group-VI transition metal dichalcogenides.
Synthesis
Heating thin films of tungsten under pressure from gaseous selenium and high temperatures (>800 K) using the sputter deposition technique leads to the films crystallizing in hexagonal structures with the correct stoichiometric ratio.[3]
- W + 2 Se → WSe2
Uses
Transition metal dichalcogenides are semiconductors which have practical applications such as photo-conversion devices in solar cells. WSe2 has a band-gap around 1.35 eV with a temperature dependence of -4.6E-4 eV/K.[4] WSe2 photoelectrodes are stable in both acidic and basic conditions, making them valuable to use in solar energy systems.
References
- ↑ Holleman, A. F.; Wiberg, E. (2001), Inorganic Chemistry, San Diego: Academic Press, ISBN 0-12-352651-5
- ↑ Schutte, W.J.; De Boer, J.L.; Jellinek, F. Crystal Structures of Tungsten Disulfide and Diselenide, Journal of Solid State Chemistry, 1986, 70, 207-209. DOI: 10.1016/0022-4596(87)90057-0
- ↑ Pouzet, J.; Bernede, J.C.; Khellil, A.; Essaidi, H.; Benhida, S. Preparation and characterization of tungsten diselenide thin films, Thin Solid Films, 1992, 208, 252-259. DOI: 10.1016/0040-6090(92)90652-R
- ↑ Upadhyayula, L.C.; Loferski, J.J.; Wold, A.; Giriat, W.; Kershaw, R. Semiconducting Properties of Single Crystals of n- and p-Type Tungsten Diselenide (WSe2), Journal of Applied Physics, 1968, 39, 353-358. DOI: 10.1063/1.1655829
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