Abnormal behavior of preferred formation of the cationic vacancies from the interior in a γ-GeSe monolayer with the stereo-chemical antibonding lone-pair state

Huan, Changmeng; Cai, Yongqing; Kripalani, Devesh R.; Zhou, Kun; Qin, Ke

doi:10.1039/d2nh00573e

Cited by 9 publications

(5 citation statements)

References 51 publications

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“…Therefore, the introduction of Ge vacancy provides a way for the stabilization of in γ-GeSe. We note that a recently published paper performed a similar analysis and confirmed that Ge vacancy formation can reduce the antibonding state in γ-GeSe …”

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confidence: 93%

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Electrical Transport Properties Driven by Unique Bonding Configuration in γ-GeSe

et al. 2023

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Group IV monochalcogenides have recently shown great potential for their thermoelectric, ferroelectric, and other intriguing properties. The electrical properties of group IV monochalcogenides exhibit a strong dependence on the chalcogen type. For example, GeTe exhibits high doping concentration, whereas S/Se-based chalcogenides are semiconductors with sizable bandgaps. Here, we investigate the electrical and thermoelectric properties of γ-GeSe, a recently identified polymorph of GeSe. γ-GeSe exhibits high electrical conductivity (∼10 6 S/m) and a relatively low Seebeck coefficient (9.4 μV/K at room temperature) owing to its high p-doping level (5 × 10 21 cm −3 ), which is in stark contrast to other known GeSe polymorphs. Elemental analysis and first-principles calculations confirm that the abundant formation of Ge vacancies leads to the high pdoping concentration. The magnetoresistance measurements also reveal weak antilocalization because of spin−orbit coupling in the crystal. Our results demonstrate that γ-GeSe is a unique polymorph in which the modified local bonding configuration leads to substantially different physical properties.

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confidence: 93%

“…We note that a recently published paper performed a similar analysis and confirmed that Ge vacancy formation can reduce the antibonding state in γ-GeSe. 46 Next, we discuss the effect of SOC on γ-GeSe, as revealed by magnetoresistance (MR). The MR results showed a typical quadratic dependence on the magnetic field at all temperatures, as shown in Figure 5a.…”

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confidence: 99%

Electrical Transport Properties Driven by Unique Bonding Configuration in γ-GeSe

et al. 2023

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“…[ 44 ] Authors demonstrated that 1) V Ge showed the most stable defects regardless of Ge contents, 2) V Ge defects were formed spontaneously due to negative formation energies resulting in the Fermi level shifted below VBM, and 3) V Se were occupied with the defect states and hybridized with VBM. Very recently, Ke et al [ 45 ] revealed that the low formation energy for V Ge defect migration was originated to the antibonding coupling of the lone‐pair Ge 4 s and Se 4 p states near VBM. The V Ge defect played a role of shallow acceptor level leading to strong infrared light absorption and middle cationic Ge sublattice located V Ge defects were well passivated by Se layer, leading to long‐term stability for optoelectronic devices.…”

Section: Fundamental Properties and Theoretical Studies Of Gesementioning

confidence: 99%

Germanium Selenide: A Critical Review on Recent Advances in Material Development for Photovoltaic and Photoelectrochemical Water‐Splitting Applications

Kamble,

Shin,

Park

et al. 2023

Solar RRL

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Germanium selenide (GeSe), a new 2D semiconductor material, is an attractive material due to its excellent optoelectronic properties, which hold tremendous promise in a wide range of applications, including thin‐film solar cells (TFSCs) and photoelectrochemical (PEC) water splitting. Several attempts have been made to date in theoretical studies, high‐quality GeSe material synthesis, evaluating absorber properties, and developing efficient TFSCs and PEC devices. Using existing device topologies for chalcogenide materials, TFSCs with 5.2% efficiency and a PEC device with 3.17% solar‐to‐hydrogen efficiency have been recently developed. To enable its potential in high performances of TFSCs and PEC devices for future large‐scale applications, further improvement in materials quality, device design, and development is required. In this regard, this review provides a comprehensive overview of current advances made in GeSe material development and applications in TFSCs and PEC devices. First, the fundamental properties of GeSe material, theoretical studies, as well as in‐depth synthesis methods, are outlined. Then, key developments in GeSe‐based TFSCs and PEC devices are discussed with an emphasis on device designs. Finally, the most prominent impediments to a fundamental understanding of materials are highlighted, and perspectives on future research directions for improving material quality and device efficiency are provided.

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“…Interestingly, bulk γ-GeSe was measured to have a higher electronic conductivity than that of graphite, rendering great possibilities in battery and thermoelectric applications. Many studies have been conducted to explore the unique structure on transport properties, , thermal conductivity, , high-performance thermoelectric, , ferroelectric, magnetic properties, photocatalytic activity, defect formation, strain-engineering behaviors, , and heterostructures. − …”

Section: Introductionmentioning

confidence: 99%

Single Atomic Catalyst of Hydrogen Evolution Supported by Semimetallic γ-GeSe

Liang,

Yan,

Cai

2024

J. Phys. Chem. C

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Motivated by the recent synthesis of a new polymorph of germanium selenide (γ-GeSe) with a honeycomb lattice and an astonishingly high conductivity (even higher than graphite), here we conduct a study on the hydrogen evolution reaction (HER) electrocatalytic performance and electronic properties of γ-GeSe with respect to the thickness effect from monolayer (1L) to trilayer (3L), along with the defect effect. The band structure of γ-GeSe exhibits a camel's back-like structure near the Γ point, existing for all the layers and in the presence of dilute Se vacancy and surface adsorbate like the Pt atom, and a narrow bandgap ranging from 0.544 eV for 1L to 0.252 eV for 3L. We find that pristine γ-GeSe is electrocatalytically inert for all the layers with an endothermic uptake of hydrogen, as indicated by the calculated Gibbs free energy (ΔG H ). However, upon introduction of Se vacancies and surface Pt adsorbates, the HER performance is enhanced, with the HER activity of 1L γ-GeSe surpassing those of bilayer (2L) and 3L γ-GeSe. Moreover, an increase in defect concentration and thickness leads to a decrease in bandgap, developing semimetallic characteristics. With the absence of a transition element and solely s and p orbitals, semimetallic γ-GeSe is unique and holds great promise as a support for fabricating a single atomic catalyst for HER, and our work offers valuable insights into the rational design of 2D electrocatalysts.

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Abnormal behavior of preferred formation of the cationic vacancies from the interior in a γ-GeSe monolayer with the stereo-chemical antibonding lone-pair state

Abstract: Two-dimensional (2D) materials tend to have the preferably formation of vacancies at the outer surface. Here, contrary to the normal notion, we reveal a type of vacancy that thermodynamically initiates...

Cited by 9 publications

References 51 publications

Electrical Transport Properties Driven by Unique Bonding Configuration in γ-GeSe

Electrical Transport Properties Driven by Unique Bonding Configuration in γ-GeSe

Germanium Selenide: A Critical Review on Recent Advances in Material Development for Photovoltaic and Photoelectrochemical Water‐Splitting Applications

Single Atomic Catalyst of Hydrogen Evolution Supported by Semimetallic γ-GeSe

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