Germanium Selenide (GeSe) Crystal

CAS Number 12065-10-0

2D Materials, Low Dimensional Materials, Materials, Post-Transition Metal Chalcogenides (PTMCs), Transition Metal Chalcogenides (TMCs)

Germanium Selenide (GeSe) Crystal CAS 12065-10-0

Low price, high purity 2D metal germanium selenide crystal

For the development of next-generation electronics, optoelectronics, and nanotechnology

Germanium selenide (GeSe), CAS number 12065-10-0, belongs to the Group IV layered post-transition metal chalcogenides (PTMC). It has a puckered layer structure similar to that of black phosphorus (BP). However, unlike BP, each germanium cation is triple-coordinated with a lone electron pair pointing to the inter-layer spacing. The lone electron pair thus is subject to inter-layer coupling to enhance the binding force between layers.

High Purity

High purity Germanium Selenide ≥99.995% crystal

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Low price Germanium Selenide

Different Forms

Available in crystals

High quality transition metal chalcogenide monolayers have mostly been fabricated by mechanical and chemical exfoliations from bulk crystals. However, few-to-monolayer GeSe films with direct bandgaps are still hard to obtain by mechanical exfoliation due to the high fragility of GeSe mono-crystalline flakes. Liquid-phase exfoliation of high-purity crystals is an alternative way to prepare GeSe nanosheets or nanoparticles.

The strong covalent bonds within the layer but weak van der Waals interactions between the layers leads to the elimination of dangling bonds and surface states, which provides chemically-inert surfaces and considerably high chemical and environmental stability. So unlike phosphorene, devices based on GeSe provide greater stability and resistance to oxidation.

GeSe is the only Group IV mono-chalcogenide (MX) that has a direct bandgap. It has closely-placed direct and indirect bandgaps that overlap well with the solar spectrum, making it a potential material for photovoltaic and photodetecting applications. Germanium selenide (GeSe) is also the most attractive group IV chalcogenide due to its structural robustness, with isotropic lithiation kinetics and high rate capability.

GeSe is also earth-abundant and environmentally-friendly, which makes it a particularly attractive candidate for applications like semiconductors. Out of its five free-standing polymorph forms, β-GeSe, γ-GeSe, δ-GeSe and ε-GeSe are indirect gap semiconductors, whereas α-GeSe is not.

Bulk single Germanium selenide crystal is most commonly used as sources from which single or few-layer sheets can be obtained via either mechanical or liquid exfoliation. Germanium selenide powder can also be used to prepare GeSe nanosheets and nanoparticles by liquid-exfoliation (normally assisted by sonication).

Technical Data

CAS Number	12065-10-0
Chemical Formula	GeSe
Molecular Weight	151.60 g/mol
Bandgap	1.07 eV
Preparation	Synthetic - Chemical Vapour Transport (CVT)
Structure	Orthorhombic
Electronic Properties	2D semiconductor
Melting Point	667 °C (decompose)
Colour	Dark brown
Synonyms	Germanium(II) selenide, Selanylidenegermanium
Classification / Family	Transition metal monochalcogenides (TMMCs), 2D semiconductor materials, Nano-electronics, Nano-photonics, Photovoltaic, Materials science

Product Details

Form	Purity
Crystal	≥99.999%

Pricing Table

Product Code	Form	Size/Weight*	Price
M2137A10	Crystal	Small (≥10 mm²)	£520 ea.

*typical representative size, areas/dimensions may vary

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MSDS Documents

Germanium selenide crystal

Structure of Germanium Selenide

Germanium selenide (GeSe) belongs to the Group IV layered metal mono-chalcogenides. It has a similar structure to phosphorene, and crystallises in a highly anisotropic layered orthorhombic (distorted NaCl-type) crystal structure with Pnma symmetry. Each primitive unit cell of the orthorhombic crystal structure contains eight atoms organised in adjacent double-puckered layers. The atoms in each double puckered layer bond to their three nearest neighbours by covalent bonds and form a zigzag chain along the direction of the minor axis of the crystal.

germanium selenide crystal structure - GeSe — Top and side view of single-layer germanium selenide (GeSe)

Properties of Germanium Selenide

After exfoliation of crystals or powder, germanium selenide typically has the following properties:

Group IV layered metal mono-chalcogenides
Puckered layer structure similar to that of black phosphorus.
Orthorhombic (distorted NaCl-type) crystal structure (Space group Pnma)
Chemically-inert surfaces and considerably high chemical and environmental stability
Closely-placed direct and indirect bandgaps that overlap well with the solar spectrum

Germanium Selenide Applications

Germanium selenide single crystals can be used to prepare monolayer and few-layer GeSe by mechanical or liquid exfoliation. Germanium Selenide powder is suitable for liquid chemical exfoliation to prepare GeSe nanosheets and nanoparticles down to few-layer films.

Germanium Selenide is a promising semiconductor for electronic and opto-electronic applications (such as photovoltaics, phototransistors, thermoelectrics, and energy storage devices.

Germanium selenide is a p-type semiconductor with closely-located direct and indirect band gaps in the range of 1.1 – 1.2 eV. GeSe also exhibits a high absorption coefficient of ~105 cm⁻¹ in the visible range and a high hole mobility of 128.6 cm² V⁻¹ s⁻¹, making it a promising semiconductor for electronic and opto-electronic applications (such as photovoltaics, phototransistors, thermoelectrics, and energy storage devices.

The GeSe layered structure with strongly-pronounced anisotropy of physical properties is a promising material for the manufacturing of photodetectors, lasers in the near-infrared range, thermo-electric, high-capacity lithium ion batteries, and photovoltaic devices.

Literature and Reviews

Electronic structure of germanium selenide investigated using ultra-violet photoelectron spectroscopy, P Mishra et al., Semicond. Sci. Technol., 30, 075001 (2015); doi:10.1088/0268-1242/30/7/075001.
Structural and electronic properties of atomically thin germanium selenide polymorphs, S. Zhang et al., Sci China Mater., 58: 929–935 (2015); doi: 10.1007/s40843-015-0107-5.
Layered material GeSe and vertical GeSe/MoS2 p-n heterojunctions, W. Yap et al., Nano Res., 11(1): 420–430 (2018); doi: 10.1007/s12274-017-1646-8.

Germanium and Tin Selenide Nanocrystals for High-Capacity Lithium Ion Batteries: Comparative Phase Conversion of Germanium and Tin, H. Im et al., J. Phys. Chem. C, 118, 21884−21888 (2014); dio: 10.1021/jp507337c.
Short-Wave Near-Infrared Linear Dichroism of Two-Dimensional Germanium Selenide, X. Wang etal., J. Am. Chem. Soc., 139, 14976-14982 (2017); DOI: 10.1021/jacs.7b06314.
Temperature induced phonon behaviour in germanium selenide thin films probed by Raman spectroscopy, J. Phys. D: Appl. Phys., 49, 315301 (2016); doi:10.1088/0022-3727/49/31/315301.
Band Structure and Photoelectric Characterization of GeSe Monolayers, H. Zhao et al., Adv. Funct. Mater., 28, 1704855 (2018); DOI: 10.1002/adfm.201704855.
Nanocomb Architecture Design Using Germanium Selenide as High- Performance Lithium Storage Material, H. Kim et al., Chem. Mater., 28, 6146−6151 (2016); DOI: 10.1021/acs.chemmater.6b02016.
GeSe monolayer semiconductor with tunable direct band gap and small carrier effective mass, Y. Hu et al., Appl. Phys. Lett. 107, 122107 (2015); doi: 10.1063/1.4931459.
Two-Dimensional GeSe as an Isostructural and Isoelectronic Analogue of Phosphorene: Sonication-Assisted Synthesis, Chemical Stability, and Optical Properties, Y. Ye et al., Chem. Mater., 29, 8361−8368 (2017); DOI: 10.1021/acs.chemmater.7b02784.
Anisotropic Spin Transport and Strong Visible-Light Absorbance in Few-Layer SnSe and GeSe, G. Shi et al., Nano Lett., 15, 6926−6931 (2015); DOI: 10.1021/acs.nanolett.5b02861.
Band Structure and Photoelectric Characterization of GeSe Monolayers, Adv. Funct. Mater., 28, 1704855 (2018); DOI: 10.1002/adfm.201704855.
Highly Anisotropic GeSe Nanosheets for Phototransistors with Ultrahigh Photoresponsivity, X. Zhou et al., Adv. Sci., 5, 1800478 (2018); DOI: 10.1002/advs.201800478.

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