*typical representative size, areas/dimensions may vary
**item with a lead time of 2-3 weeks, please contact for more information
||1.41 - 1.58 eV 
||Molybdenum (IV) selenide
|Classification / Family
Transition metal dichalcogenides (TMDCs), 2D semiconductor Materials, Nano-electronics, Nano-photonics, Electrochemical energy storage system, Materials science
||Synthetic - Chemical Vapour Transport (CVT)
Like most of the transition metal dichalcogenides and graphite, molybdenum diselenide (MoSe2) has a two-dimensional layered structure - with the individual layers stacked together by weak van der Waals interactions. Due to the larger size and better conductivity of selenium over sulphur, MoSe2 is one of the best TMDCs of metallic nature. This also provides a great opportunity for hosting counterions in electrochemical energy storage systems (such as lithium-ion and sodium-ion batteries).
Like MoS2, MoSe2 undergoes changes from indirect to direct band-gap transitions when bulk material (such as the bulk crystal) is reduced to monolayer film. However, unlike MoS2, few-layer MoSe2 flakes possess a nearly degenerate indirect and direct band-gap. An increase in temperature/pressure can effectively push the system toward the quasi-2D limit by reducing the coupling between the layers. MoS2, on the other hand, has indirect and direct band-gaps that are well-separated in energy - and hence, far from degenerate.
Compared to MoS2, MoSe2 exhibits higher electrical conductivity.
In contrast to graphene, exfoliated monolayer or few-layer 2D MoSe2 has a direct band-gap. It has applications in transistors, photo-detectors, and photovoltaics. Due to its layered structure and the unique nature of selenium, MoSe2 has been widely used in lubricants and energy storage devices.
Molybdenum diselenide MoSe2 is manufactured via the process of chemical vapour transport (CVT) crystallisation, with purities of over 99.999% achieved.
Molybdenum diselenide MoSe2 single crystals are a great source for obtaining monolayer and few-layer MoSe2 via mechanical or liquid exfoliation. Single crystals can also be used directly in optical and scanning-probe microscopy (such as AFM and TEM studies).
Literature and Reviews
Direct observation of the transition from indirect to direct bandgap in atomically thin epitaxial MoSe2, Y. Zhang et al., Nat. Nanotech., 9, 111–115 (2014); DOI: 10.1038/NNANO.2013.277.
Large-Area Synthesis of Monolayer and Few-Layer MoSe2 Films on SiO2 Substrates, X. Lu et al., Nano Lett., 14 (5), 2419–2425 (2014); DOI: 10.1021/nl5000906.
High-Mobility Transistors Based on Large-Area and Highly Crystalline CVD-Grown MoSe 2 Films on Insulating Substrates, J-S. Rhyee et al., Adv. Mater., 28, 2316–2321 (2016); DOI: 10.1002/adma.201504789.
Large-Area Single-Layer MoSe2 and Its van der Waals Heterostructures, G. Shim et al., CS Nano, 8 (7), 6655–6662 92014);
Thermally Driven Crossover from Indirect toward Direct Bandgap in 2D Semiconductors: MoSe2 versus MoS2, S. Tongay et al., Nano Lett., 12, 5576−5580 (2012); DOI: 10.1021/nl302584w.