Tungsten diselenide

Identifiers

CAS Number

* 12067-46-8

3D model (JSmol)

* Interactive image

ChemSpider |

* 60601189

EC Number |

* 235-078-7

PubChem CID

* 82910

InChI

* InChI=1S/2Se.W

Key: ROUIDRHELGULJS-UHFFFAOYSA-N

SMILES

* [Se]=[W]=[Se]

Properties

Chemical formula

| WSe2
Molar mass | 341.76 g/mol
Appearance  | grey to black solid
Odor | odorless
Density | 9.32 g/cm3[1]
Melting point | > 1200 °C

Solubility in water

| insoluble
Band gap | ~1 eV (indirect, bulk)[2]
~1.7 eV (direct, monolayer)[3]
Structure

Crystal structure

| hP6, space group P63/mmc, No 194[1]

Lattice constant

a = 0.3297 nm, c = 1.2982 nm

Coordination geometry

| Trigonal prismatic (WIV)
Pyramidal (Se2−)
Thermochemistry

Std enthalpy of
formation (ΔfH⦵298)

| −185.3 kJ mol−1[4]
Hazards
Main hazards | External MSDS
GHS pictograms |
GHS Signal word | Warning

GHS hazard statements

| H301, H331, H373, H410

GHS precautionary statements

| P260, P261, P264, P270, P271, P273, P301+316Script error: No such module "Preview warning".Category:GHS errors, P304+340, P316Script error: No such module "Preview warning".Category:GHS errors, P319Script error: No such module "Preview warning".Category:GHS errors, P321, P330, P391, P403+233, P405, P501
Related compounds

Other anions

| Tantalum diselenide

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Infobox references

Tracking categories (test):

* SizeSet

Tungsten diselenide is an inorganic compound with the formula WSe2.[5] The compound adopts a hexagonal crystalline structure similar to molybdenum disulfide. The tungsten atoms are 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 length of 0.2526 nm, and the distance between selenium atoms is 0.334 nm.[6] It is a well studied example of a layered material. The layers stack together via van der Waals interactions. WSe2 is a very stable semiconductor in the group-VI transition metal dichalcogenides.

## Contents

* 1 Structure and properties
* 2 Synthesis
* 3 Potential applications
* 4 See also
* 5 References

## Structure and properties

The hexagonal (P63/mmc) polymorph 2H-WSe2 is isotypic with hexagonal MoS2. The two-dimensional lattice structure has W and Se arranged periodically in layers with hexagonal symmetry. Similar to graphite, van der Waals interactions hold the layers together; however, the 2D-layers in WSe2 are not atomically thin. The large size of the W cation renders the lattice structure of WSe2 more sensitive to changes than MoS2.[7]

In addition to the typical semiconducting hexagonal structure, a second metallic polymorph of WSe2 exists. This phase, 1T-WSe2, is based on a tetragonal symmetry with one WSe2 layer per repeating unit. The 1T-WSe2 phase is less stable and transitions to the 2H-WSe2 phase.[7][8] WSe2 can form a fullerene-like structure.

The Young's modulus varies greatly as a function of the number of layers in a flake. For a single monolayer, the reported Young's modulus is 258.6 ± 38.3 GPa.[9]

## 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.[10]

W + 2 Se → WSe2

## Potential applications

Atomic image of a WSe2 monolayer showing hexagonal symmetry and three-fold defects. Scale bar: 2 nm (0.5 nm in the inset).[11]

The potential applications of transition metal dichalcogenides in solar cells and photonics are often discussed.[12] Bulk WSe2 has an optical band gap of ~1.35 eV with a temperature dependence of −4.6×10−4 eV/K.[13] WSe2 photoelectrodes are stable in both acidic and basic conditions, making them potentially useful in electrochemical solar cells.[14][15][16]

The properties of WSe2 monolayers differ from those of the bulk state, as is typical for semiconductors. Mechanically exfoliated monolayers of WSe2 are transparent photovoltaic materials with LED properties.[17] The resulting solar cells pass 95 percent of the incident light, with one tenth of the remaining five percent converted into electrical power.[18][19] The material can be changed from p-type to n-type by changing the voltage of an adjacent metal electrode from positive to negative, allowing devices made from it to have tunable bandgaps.[20]

Superconductivity has been reported in twisted bilayer WSe2, with a transition temperature of 200 mK.[21]

## See also

* Transition metal dichalcogenide monolayers

## References

1. ↑ 1.0 1.1 Agarwal, M. K.; Wani, P. A. (1979). "Growth conditions and crystal structure parameters of layer compounds in the series Mo1−xWxSe2". Materials Research Bulletin 14 (6): 825–830. doi:10.1016/0025-5408(79)90144-2.
2. ↑ Prakash, Abhijith; Appenzeller, Joerg (2017-02-28). "Bandgap Extraction and Device Analysis of Ionic Liquid Gated WSe2 Schottky Barrier Transistors". ACS Nano 11 (2): 1626–1632. doi:10.1021/acsnano.6b07360. ISSN 1936-0851. PMID 28191930.
3. ↑ Yun, Won Seok; Han, S. W.; Hong, Soon Cheol; Kim, In Gee; Lee, J. D. (2012). "Thickness and strain effects on electronic structures of transition metal dichalcogenides: 2H-MX2 semiconductors (M = Mo, W; X = S, Se, Te)". Physical Review B 85 (3). doi:10.1103/PhysRevB.85.033305. Bibcode: 2012PhRvB..85c3305Y.
4. ↑ O'Hare, P.A.G.; Lewis, Brett M.; parkinson, B.A. (June 1988). "Standard molar enthalpy of formation by fluorine-combustion calorimetry of tungsten diselenide (WSe2). Thermodynamics of the high-temperature vaporization of WSe2. Revised value of the standard molar enthalpy of formation of molybdenite (MoS2)" (in en). The Journal of Chemical Thermodynamics 20 (6): 681–691. doi:10.1016/0021-9614(88)90019-5.
5. ↑ Holleman, Arnold Frederik; Wiberg, Egon (2001), Wiberg, Nils, ed., Inorganic Chemistry, San Diego/Berlin: Academic Press/De Gruyter, ISBN 0-12-352651-5
6. ↑ Schutte, W.J.; De Boer, J.L.; Jellinek, F. (1986). "Crystal Structures of Tungsten Disulfide and Diselenide". Journal of Solid State Chemistry 70 (2): 207–209. doi:10.1016/0022-4596(87)90057-0. Bibcode: 1987JSSCh..70..207S.
7. ↑ 7.0 7.1 Eftekhari, Ali (2017). "Tungsten dichalcogenides (WS 2, WSe 2, and WTe 2 ): materials chemistry and applications" (in en). Journal of Materials Chemistry A 5 (35): 18299–18325. doi:10.1039/C7TA04268J. ISSN 2050-7488. http://xlink.rsc.org/?DOI=C7TA04268J.
8. ↑ Ma, Yuqiang; Liu, Bilu; Zhang, Anyi; Chen, Liang; Fathi, Mohammad; Shen, Chenfei; Abbas, Ahmad N.; Ge, Mingyuan et al. (2015-07-28). "Reversible Semiconducting-to-Metallic Phase Transition in Chemical Vapor Deposition Grown Monolayer WSe 2 and Applications for Devices" (in en). ACS Nano 9 (7): 7383–7391. doi:10.1021/acsnano.5b02399. ISSN 1936-0851. PMID 26125321.
9. ↑ Falin, Alexey; Holwill, Matthew; Lv, Haifeng; Gan, Wei; Cheng, Jun; Zhang, Rui; Qian, Dong; Barnett, Matthew R. et al. (23 February 2021). "Mechanical Properties of Atomically Thin Tungsten Dichalcogenides: WS 2, WSe 2, and WTe 2". ACS Nano 15 (2): 2600–2610. doi:10.1021/acsnano.0c07430. PMID 33503379.
10. ↑ Pouzet, J.; Bernede, J.C.; Khellil, A.; Essaidi, H.; Benhida, S. (1992). "Preparation and characterization of tungsten diselenide thin films". Thin Solid Films 208 (2): 252–259. doi:10.1016/0040-6090(92)90652-R. Bibcode: 1992TSF...208..252P.
11. ↑ Lin, Y. C.; Björkman, T. R.; Komsa, H. P.; Teng, P. Y.; Yeh, C. H.; Huang, F. S.; Lin, K. H.; Jadczak, J. et al. (2015). "Three-fold rotational defects in two-dimensional transition metal dichalcogenides". Nature Communications 6. doi:10.1038/ncomms7736. PMID 25832503. Bibcode: 2015NatCo...6.6736L.
12. ↑ Mak, Kin Fai; Shan, Jie (2016). "Photonics and optoelectronics of 2D semiconductor transition metal dichalcogenides". Nature Photonics 10 (4): 216–226. doi:10.1038/nphoton.2015.282. Bibcode: 2016NaPho..10..216M.
13. ↑ Upadhyayula, L.C.; Loferski, J.J.; Wold, A.; Giriat, W.; Kershaw, R. (1968). "Semiconducting Properties of Single Crystals of n- and p-Type Tungsten Diselenide (WSe2)". Journal of Applied Physics 39 (10): 353–358. doi:10.1063/1.1655829. Bibcode: 1968JAP....39.4736U.
14. ↑ Gobrecht, J.; Gerischer, H.; Tributsch, H. (1978). "Electrochemical Solar Cell Based on the d-Band Semiconductor Tungsten-Diselenide". Berichte der Bunsengesellschaft für physikalische Chemie 82 (12): 1331–1335. doi:10.1002/bbpc.19780821212.
15. ↑ Xia, Fengnian; Wang, Han; Xiao, Di; Dubey, Madan; Ramasubramaniam, Ashwin (2014). "Two-dimensional material nanophotonics". Nature Photonics 8 (12): 899–907. doi:10.1038/nphoton.2014.271. Bibcode: 2014NaPho...8..899X.
16. ↑ Zhang, Xin; Qiao, Xiao-Fen; Shi, Wei; Wu, Jiang-Bin; Jiang, De-Sheng; Tan, Ping-Heng (2015). "Phonon and Raman scattering of two-dimensional transition metal dichalcogenides from monolayer, multilayer to bulk material". Chem. Soc. Rev. 44 (9): 2757–85. doi:10.1039/C4CS00282B. PMID 25679474. Bibcode: 2015arXiv150200701Z.
17. ↑ Li, Hai; Wu, Jumiati; Yin, Zongyou; Zhang, Hua (2014). "Preparation and Applications of Mechanically Exfoliated Single-Layer and Multilayer MoS2 and WSe2 Nanosheets". Accounts of Chemical Research 47 (4): 1067–1075. doi:10.1021/ar4002312. PMID 24697842.
18. ↑ "Tungsten diselenide shows potential for ultrathin, flexible, semi-transparent solar cells". Gizmag.com. 11 March 2014. http://www.gizmag.com/tungsten-diselenide-solar-cells/31161.
19. ↑ Florian Aigenr (10 March 2014). "Atomically thin solar cells" (Press release). Vienna University of Technology. Retrieved 18 August 2014.
20. ↑ Lee, Sung-Joon; Lin, Zhaoyang; Huang, Jin; Choi, Christopher; Chen, Peng; Liu, Yuan; Guo, Jian; Jia, Chuancheng et al. (2020). "Programmable devices based on reversible solid-state doping of two-dimensional semiconductors with superionic silver iodide". Nature Electronics 3 (10): 630–637. doi:10.1038/s41928-020-00472-x.
21. ↑ Xia, Yiyu; Han, Zhongdong; Watanabe, Kenji; Taniguchi, Takashi; Shan, Jie; Mak, Kin Fai (30 October 2024). "Superconductivity in twisted bilayer WSe2" (in en). Nature 637 (8047): 833–838. doi:10.1038/s41586-024-08116-2. ISSN 1476-4687. PMID 39478226. https://www.nature.com/articles/s41586-024-08116-2. Retrieved 13 January 2025.

* v
* t
* e

Tungsten compounds

Tungsten(0)|

* W(CO)6

Tungsten(II)|

* WSi2
* WCl2
* W(OH)2

Tungsten(III)|

* W2O3

Tungsten(IV)|

* WC
* WO2
* WS2
* WSe2
* WTe2
* WF4
* WCl4

Tungsten(V)|

* W2O5
* WBr5
* W2Cl10

Tungsten(VI)|

* H3PW12O40
* (NH4)10(H2W12O42)
* WO2Cl2
* WCl6
* WF6
* WN2
* WO3
* WS3
* WOBr4
* WOCl4
* WOF4
* H2WO4

| Organotungsten(VI) compounds|

* W(CH3)6

|

* v
* t
* e

Selenides

| H2Se
H2Se2 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | He

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Li2Se | Be |  |  |  |  |  |  |  |  |  |  | B | CSe2
OCSe | (NH4)2Se | O | F | Ne
Na2Se | MgSe |  |  |  |  |  |  |  |  |  |  | Al2Se3 | Si | PxSey | S | Cl | Ar
K2Se | CaSe | Sc2Se3 | TiSe2 | V | CrSe
Cr2Se3 | MnSe
MnSe2 | FeSe | CoSe | NiSe | CuSe | ZnSe | GaSe
Ga2Se3 | GeSe | As2Se3
As4Se3 | Se | Br | Kr
Rb2Se | SrSe | Y2Se3 | Zr | NbSe2
NbSe3 | MoSe2 | Tc | Ru | Rh | Pd | Ag2Se | CdSe | In2Se3 | SnSe
SnSe2 | Sb2Se3 | Te | I | Xe
Cs2Se | BaSe | *  | Hf | Ta | WSe2
WSe3 | ReSe2 | Os | Ir | Pt | Au | HgSe | Tl2Se | PbSe | Bi2Se3 | Po | At | Rn
Fr | Ra | **  | Rf | Db | Sg | Bh | Hs | Mt | Ds | Rg | CnSe | Nh | Fl | Mc | Lv | Ts | Og |  |  |  |  |  |  |  |
|  | ↓ |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| * | La2Se3 | Ce2Se3 | Pr2Se3 | Nd2Se3 | Pm | Sm2Se3 | Eu2Se3 | Gd | Tb | Dy | Ho | Er2Se3 | Tm2Se3 | Yb | Lu |
| ** | Ac | ThSe2 | Pa | USe2 | Np | Pu | Am | Cm | Bk | Cf | Es | Fm | Md | No | Lr |

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*[CID]: Compound ID
*[H301]: Toxic if swallowed
*[H331]: Toxic if inhaled
*[H373]: May cause damage to organs through prolonged or repeated exposure
*[H410]: Very toxic to aquatic life with long lasting effects
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*[P261]: Avoid breathing dust/fume/gas/mist/vapours/spray
*[P264]: Wash … thoroughly after handling
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*[P304+340]: IF INHALED: Remove victim to fresh air and keep at rest in a position comfortable for breathing
*[P321]: Specific treatment (see … on this label)
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