Journal articles: '2D-TMDs materials'

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Tung, Vincent. "(Keynote) Wafer-Scale Epitaxy of 2D Materials with Uniformity, Single Crystallinity, and Low Defect Density." ECS Meeting Abstracts MA2024-02, no. 35 (November 22, 2024): 2448. https://doi.org/10.1149/ma2024-02352448mtgabs.

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Two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs) representing the ultimate thickness scaling of channel materials provide a solution to tantalizingly push the limit of technology nodes in the sub-1-nm range. One key challenge with 2D semiconducting TMDs channel materials is the large-scale batch growth on insulating substrates with continuous single crystallinity, spatial homogeneity, and compelling electrical properties. Recent studies have claimed the epitaxy growth of wafer-scale, single-crystal 2D TMDs on C-plane sapphire substrate with deliberately engineered off-cut angles. It has been predominately postulated that exposed step edges break the energy degeneracy of nucleation and thus drive the seamless stitching of mono-oriented flakes. In this talk, I will show that a more dominant factor should be considered. The interaction of 2D TMD grains with the exposed oxygen-aluminum atomic plane establishes an energy-minimized 2D TMD-sapphire configuration. Reconstructing the surfaces of C-plane sapphire substrates to only a single type (symmetry) of atomic planes already guarantees the single-crystal epitaxy of monolayer TMDs without the aid of step edges. Electrical results also evidence the structural uniformity of the monolayers. Our new experimental findings elucidate the long-standing question that curbs the wafer-scale batch epitaxy of 2D TMDs single crystals, an essential step toward using 2D materials for future electronics. Experiments extended to other materials like perovskites also support the argument that the interaction with sapphire atomic surfaces is more dominant than the step edge docking.

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Acosta, Selene, and Mildred Quintana. "Chemically Functionalized 2D Transition Metal Dichalcogenides for Sensors." Sensors 24, no. 6 (March 12, 2024): 1817. http://dx.doi.org/10.3390/s24061817.

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The goal of the sensor industry is to develop innovative, energy-efficient, and reliable devices to detect molecules relevant to economically important sectors such as clinical diagnoses, environmental monitoring, food safety, and wearables. The current demand for portable, fast, sensitive, and high-throughput platforms to detect a plethora of new analytes is continuously increasing. The 2D transition metal dichalcogenides (2D-TMDs) are excellent candidates to fully meet the stringent demands in the sensor industry; 2D-TMDs properties, such as atomic thickness, large surface area, and tailored electrical conductivity, match those descriptions of active sensor materials. However, the detection capability of 2D-TMDs is limited by their intrinsic tendency to aggregate and settle, which reduces the surface area available for detection, in addition to the weak interactions that pristine 2D-TMDs normally exhibit with analytes. Chemical functionalization has been proposed as a consensus solution to these limitations. Tailored surface modification of 2D-TMDs, either by covalent functionalization, non-covalent functionalization, or a mixture of both, allows for improved specificity of the surface–analyte interaction while reducing van der Waals forces between 2D-TMDs avoiding agglomeration and precipitation. From this perspective, we review the recent advances in improving the detection of biomolecules, heavy metals, and gases using chemically functionalized 2D-TMDs. Covalent and non-covalent functionalized 2D-TMDs are commonly used for the detection of biomolecules and metals, while 2D-TMDs functionalized with metal nanoparticles are used for gas and Raman sensors. Finally, we describe the limitations and further strategies that might pave the way for miniaturized, flexible, smart, and low-cost sensing devices.

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Ma, Yuanji, Yuhan Du, Wenbin Wu, Zeping Shi, Xianghao Meng, and Xiang Yuan. "Synthesis and Characterization of 2D Ternary Compound TMD Materials Ta3VSe8." Micromachines 15, no. 5 (April 28, 2024): 591. http://dx.doi.org/10.3390/mi15050591.

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Two-dimensional (2D) transition metal dichalcogenides (TMDs) are garnering considerable scientific interest, prompting discussion regarding their prospective applications in the fields of nanoelectronics and spintronics while also fueling groundbreaking discoveries in phenomena such as the fractional quantum anomalous Hall effect (FQAHE) and exciton dynamics. The abundance of binary compound TMDs, such as MX2 (M = Mo, W; X = S, Se, Te), has unlocked myriad avenues of exploration. However, the exploration of ternary compound TMDs remains relatively limited, with notable examples being Ta2NiS5 and Ta2NiSe5. In this study, we report the synthesis of a new 2D ternary compound TMD materials, Ta3VSe8, employing the chemical vapor transport (CVT) method. The as-grown bulk crystal is shiny and can be easily exfoliated. The crystal quality and structure are verified by X-ray diffraction (XRD), while the surface morphology, stoichiometric ratio, and uniformity are determined by scanning electron microscopy (SEM). Although the phonon property is found stable at different temperatures, magneto-resistivity evolves. These findings provide a possible approach for the realization and exploration of ternary compound TMDs.

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Ekengoue, C. M., C. Kenfack-Sadem, J. E. Danga, G. N. Bawe, A. El Moussaouy, O. Mommadi, L. Belamkadem, and L. C. Fai. "Polariton condensate and Landau-Zener-Stückelberg interferometry transition in multilayer transition metal dichalcogenides." Physica Scripta 97, no. 2 (January 13, 2022): 025801. http://dx.doi.org/10.1088/1402-4896/ac4718.

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Abstract This paper gives a detailed description of a high-performance polariton condensate for a quantum mechanical two-level system (TLS). We propose a transition metal dichalcogenides (TMDs) setup and theoretically carry out the spectroscopy of these polariton condensates. Through theoretical and numerical analysis, we obtain many features in two dimensional (2D) multilayer TMDs. We compute the energy of the system and the Landau-Zener-Stückelberg (LZS) quantum tunneling probability under the effect of a sequence of laser light. At certain critical 2D TMDs parameters, the system exhibits a multi-crossing scenario in a privileged position of 2D multilayer TMDs. We predict the consecutive modulations and highlight the conservation of the LZS interference patterns mapped from the 2D TMDs system. At weak coupling regime, a successful conversion of interferometry signals is identified for some values of laser frequency. We explain such a result as a valley sensitive cavity rate model due to coherent exchange and incoherent scattering, meaning that polariton condensate is formed in the valley around the Brillouin zone. The latter is used quantitatively and qualitatively to achieve high-precision measurements beyond that of its elementary constituents. The obtained results confirm that M o S e 2 has the highest sensitivity to radiation field as compared to other 2D multilayer TMDs materials. Therefore, M o S e 2 stands as an appropriate candidate among other 2D TMDs to form polariton condensates.

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Ghosh, Dibyendu, Pooja Devi, and Praveen Kumar. "Intercalation in two-dimensional transition metal chalcogenides: interlayer engineering and applications." Progress in Energy 4, no. 2 (January 21, 2022): 022001. http://dx.doi.org/10.1088/2516-1083/ac3c3d.

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Abstract Intercalation is basically the process of putting one or multiple guest elements into the van der Waals gaps of a parent crystal in a reversible way. Two-dimensional (2D) materials have shown great promise with intercalant species ranging from organic molecules to ions. Apart from graphene, the most studied 2D materials are the transition metal dichalcogenides (TMDs). Intercalation in TMDs has led to new strategies beyond graphene for 2D structures in materials science, materials engineering, chemistry and physics. This review deals with the possible mechanism of intercalation as well as the window that intercalation can open for compact and ultrathin device technology. Modulation of the physicochemical properties of intercalated TMDs has been thoroughly reviewed. Finally, device performance, especially for energy storage and energy harvesting devices, has been evaluated and specific issues that need attention for future development are highlighted.

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Chen, Chueh-An, Chiao-Lin Lee, Po-Kang Yang, Dung-Sheng Tsai, and Chuan-Pei Lee. "Active Site Engineering on Two-Dimensional-Layered Transition Metal Dichalcogenides for Electrochemical Energy Applications: A Mini-Review." Catalysts 11, no. 2 (January 21, 2021): 151. http://dx.doi.org/10.3390/catal11020151.

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Two-dimensional-layered transition metal dichalcogenides (2D-layered TMDs) are a chemically diverse class of compounds having variable band gaps and remarkable electrochemical properties, which make them potential materials for applications in the field of electrochemical energy. To date, 2D-layered TMDs have been wildly used in water-splitting systems, dye-sensitized solar cells, supercapacitors, and some catalysis systems, etc., and the pertinent devices exhibit good performances. However, several reports have also indicated that the active sites for catalytic reaction are mainly located on the edge sites of 2D-layered TMDs, and their basal plane shows poor activity toward catalysis reaction. Accordingly, many studies have reported various approaches, namely active-site engineering, to address this issue, including plasma treatment, edge site formation, heteroatom-doping, nano-sized TMD pieces, highly curved structures, and surface modification via nano-sized catalyst decoration, etc. In this article, we provide a short review for the active-site engineering on 2D-layered TMDs and their applications in electrochemical energy. Finally, the future perspectives for 2D-layered TMD catalysts will also be briefly discussed.

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Mia, Abdul Kaium, M. Meyyappan, and P. K. Giri. "Two-Dimensional Transition Metal Dichalcogenide Based Biosensors: From Fundamentals to Healthcare Applications." Biosensors 13, no. 2 (January 21, 2023): 169. http://dx.doi.org/10.3390/bios13020169.

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There has been an exponential surge in reports on two-dimensional (2D) materials ever since the discovery of graphene in 2004. Transition metal dichalcogenides (TMDs) are a class of 2D materials where weak van der Waals force binds individual covalently bonded X–M–X layers (where M is the transition metal and X is the chalcogen), making layer-controlled synthesis possible. These individual building blocks (single-layer TMDs) transition from indirect to direct band gaps and have fascinating optical and electronic properties. Layer-dependent opto-electrical properties, along with the existence of finite band gaps, make single-layer TMDs superior to the well-known graphene that paves the way for their applications in many areas. Ultra-fast response, high on/off ratio, planar structure, low operational voltage, wafer scale synthesis capabilities, high surface-to-volume ratio, and compatibility with standard fabrication processes makes TMDs ideal candidates to replace conventional semiconductors, such as silicon, etc., in the new-age electrical, electronic, and opto-electronic devices. Besides, TMDs can be potentially utilized in single molecular sensing for early detection of different biomarkers, gas sensors, photodetector, and catalytic applications. The impact of COVID-19 has given rise to an upsurge in demand for biosensors with real-time detection capabilities. TMDs as active or supporting biosensing elements exhibit potential for real-time detection of single biomarkers and, hence, show promise in the development of point-of-care healthcare devices. In this review, we provide a historical survey of 2D TMD-based biosensors for the detection of bio analytes ranging from bacteria, viruses, and whole cells to molecular biomarkers via optical, electronic, and electrochemical sensing mechanisms. Current approaches and the latest developments in the study of healthcare devices using 2D TMDs are discussed. Additionally, this review presents an overview of the challenges in the area and discusses the future perspective of 2D TMDs in the field of biosensing for healthcare devices.

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Kim, Youngbum, and Jeongyong Kim. "Near-field optical imaging and spectroscopy of 2D-TMDs." Nanophotonics 10, no. 13 (September 29, 2021): 3397–415. http://dx.doi.org/10.1515/nanoph-2021-0383.

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Abstract Two-dimensional transition metal dichalcogenides (2D-TMDs) are atomically thin semiconductors with a direct bandgap in monolayer thickness, providing ideal platforms for the development of exciton-based optoelectronic devices. Extensive studies on the spectral characteristics of exciton emission have been performed, but spatially resolved optical studies of 2D-TMDs are also critically important because of large variations in the spatial profiles of exciton emissions due to local defects and charge distributions that are intrinsically nonuniform. Because the spatial resolution of conventional optical microscopy and spectroscopy is fundamentally limited by diffraction, near-field optical imaging using apertured or metallic probes has been used to spectrally map the nanoscale profiles of exciton emissions and to study the effects of nanosize local defects and carrier distribution. While these unique approaches have been frequently used, revealing information on the exciton dynamics of 2D-TMDs that is not normally accessible by conventional far-field spectroscopy, a dedicated review of near-field imaging and spectroscopy studies on 2D-TMDs is not available. This review is intended to provide an overview of the current status of near-field optical research on 2D-TMDs and the future direction with regard to developing nanoscale optical imaging and spectroscopy to investigate the exciton characteristics of 2D-TMDs.

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Dou, Maofeng, and Maria Fyta. "Lithium adsorption on 2D transition metal dichalcogenides: towards a descriptor for machine learned materials design." Journal of Materials Chemistry A 8, no. 44 (2020): 23511–18. http://dx.doi.org/10.1039/d0ta04834h.

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Li, Qi, Jianping Meng, and Zhou Li. "Recent progress on Schottky sensors based on two-dimensional transition metal dichalcogenides." Journal of Materials Chemistry A 10, no. 15 (2022): 8107–28. http://dx.doi.org/10.1039/d2ta00075j.

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This review highlights the advances in Schottky sensors based on 2D TMDs. The preparation methods of 2D TMDs and the vital Schottky sensors such as photodetectors, gas sensors, strain sensors, and biosensors are summarized and discussed.

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Huo, Nengjie, Yujue Yang, and Jingbo Li. "Optoelectronics based on 2D TMDs and heterostructures." Journal of Semiconductors 38, no. 3 (March 2017): 031002. http://dx.doi.org/10.1088/1674-4926/38/3/031002.

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Yu, Jia, Shiru Wu, Xun Zhao, Zhipu Li, Xiaowei Yang, Qian Shen, Min Lu, Xiaoji Xie, Da Zhan, and Jiaxu Yan. "Progress on Two-Dimensional Transitional Metal Dichalcogenides Alloy Materials: Growth, Characterisation, and Optoelectronic Applications." Nanomaterials 13, no. 21 (October 27, 2023): 2843. http://dx.doi.org/10.3390/nano13212843.

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Two-dimensional (2D) transitional metal dichalcogenides (TMDs) have garnered remarkable attention in electronics, optoelectronics, and hydrogen precipitation catalysis due to their exceptional physicochemical properties. Their utilisation in optoelectronic devices is especially notable for overcoming graphene’s zero-band gap limitation. Moreover, TMDs offer advantages such as direct band gap transitions, high carrier mobility, and efficient switching ratios. Achieving precise adjustments to the electronic properties and band gap of 2D semiconductor materials is crucial for enhancing their capabilities. Researchers have explored the creation of 2D alloy phases through heteroatom doping, a strategy employed to fine-tune the band structure of these materials. Current research on 2D alloy materials encompasses diverse aspects like synthesis methods, catalytic reactions, energy band modulation, high-voltage phase transitions, and potential applications in electronics and optoelectronics. This paper comprehensively analyses 2D TMD alloy materials, covering their growth, preparation, optoelectronic properties, and various applications including hydrogen evolution reaction catalysis, field-effect transistors, lithium-sulphur battery catalysts, and lasers. The growth process and characterisation techniques are introduced, followed by a summary of the optoelectronic properties of these materials.

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Fang, Mengqi, and Eui-Hyeok Yang. "Advances in Two-Dimensional Magnetic Semiconductors via Substitutional Doping of Transition Metal Dichalcogenides." Materials 16, no. 10 (May 12, 2023): 3701. http://dx.doi.org/10.3390/ma16103701.

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Transition metal dichalcogenides (TMDs) are two-dimensional (2D) materials with remarkable electrical, optical, and chemical properties. One promising strategy to tailor the properties of TMDs is to create alloys through a dopant-induced modification. Dopants can introduce additional states within the bandgap of TMDs, leading to changes in their optical, electronic, and magnetic properties. This paper overviews chemical vapor deposition (CVD) methods to introduce dopants into TMD monolayers, and discusses the advantages, limitations, and their impacts on the structural, electrical, optical, and magnetic properties of substitutionally doped TMDs. The dopants in TMDs modify the density and type of carriers in the material, thereby influencing the optical properties of the materials. The magnetic moment and circular dichroism in magnetic TMDs are also strongly affected by doping, which enhances the magnetic signal in the material. Finally, we highlight the different doping-induced magnetic properties of TMDs, including superexchange-induced ferromagnetism and valley Zeeman shift. Overall, this review paper provides a comprehensive summary of magnetic TMDs synthesized via CVD, which can guide future research on doped TMDs for various applications, such as spintronics, optoelectronics, and magnetic memory devices.

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Lou, Jun. "(Invited) Emerging Two-Dimensional Materials for Device Applications." ECS Meeting Abstracts MA2024-02, no. 35 (November 22, 2024): 2480. https://doi.org/10.1149/ma2024-02352480mtgabs.

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Two-dimensional (2D) materials, such as Graphene, h-BN and MoS2, are promising candidates in a number of advanced device applications, owing to their exceptional electrical, optical and mechanical properties. Scalable growth of high quality 2D materials is crucial for their adoption in technological applications the same way the arrival of high-quality silicon single crystals was to the semiconductor industry. While CVD growth of wafer-scale monolayer graphene and TMDs has been demonstrated, considerable challenges still remain. In this talk, we first report a CVD method to grow fluorine rich 2D polymer (2DP-F) on varies substrates for low-k dielectrics in 2D TMDs based devices. Using precursors with low vaporize temperature, a uniform and ultra-flat 2DP-F film with controlled thickness can be deposited on silicon oxide wafer, glass, sapphire and mica substrates. Dielectric properties and relevant mechanical properties were carefully characterized. These 2DP-F films were then used as the substrate for transition metal dichalcogenides (TMDs) based devices, and significant improvements in device performances were found, possibly owing to the ultra-smooth and dangling bond free surface of 2DP-F that can significantly reduce the interfacial scattering of carriers. Next, we show that atomically thin Cs3Bi2I9, an all-inorganic lead-free perovskite derivative with strong optical activity can be successfully synthesized by vapor growth method. Reducing the dimensionality of such perovskites could utilize the materials’ advantages for solid-state information devices like valleytronics. By breaking the inversion symmetry, 2D Cs3Bi2I9 flakes with odd-layer number exhibited persistent, optically addressable valley polarization. This study potentially opens generalizable CVD method for growing a broad range of 2D perovskites towards cost-effective and energy-efficient integrated device applications. Finally, we report a two-step vapor phase growth process for the creation of high-quality vdW heterostructures based on perovskites and TMDCs, such as 2D Cs3Bi2I9/MoSe2, with a large lattice mismatch. Supported by experimental and theoretical investigations, we discover that the Cs3Bi2I9/MoSe2 vdW heterostructure possesses hybrid band alignments consisting of type-I and type-II heterojunctions because of the existence of defect energy levels in Cs3Bi2I9. More importantly, we demonstrate that the type-II heterojunction in the Cs3Bi2I9/MoSe2 vdW heterostructure not only shows a higher interlayer exciton density, but also exhibits a longer interlayer exciton lifetime than traditional 2D TMDCs based type-II heterostructures. Such vdW heterostructures provide promising platforms for exploring novel physics and cutting-edge optoelectronics and valleytronics applications.

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Vaquero, Daniel, Juan Salvador-Sánchez, Vito Clericò, Enrique Diez, and Jorge Quereda. "The Low-Temperature Photocurrent Spectrum of Monolayer MoSe2: Excitonic Features and Gate Voltage Dependence." Nanomaterials 12, no. 3 (January 19, 2022): 322. http://dx.doi.org/10.3390/nano12030322.

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Two-dimensional transition metal dichalcogenides (2D-TMDs) are among the most promising materials for exploring and exploiting exciton transitions. Excitons in 2D-TMDs present remarkably long lifetimes, even at room temperature. The spectral response of exciton transitions in 2D-TMDs has been thoroughly characterized over the past decade by means of photoluminescence spectroscopy, transmittance spectroscopy, and related techniques; however, the spectral dependence of their electronic response is still not fully characterized. In this work, we investigate the electronic response of exciton transitions in monolayer MoSe2 via low-temperature photocurrent spectroscopy. We identify the spectral features associated with the main exciton and trion transitions, with spectral bandwidths down to 15 meV. We also investigate the effect of the Fermi level on the position and intensity of excitonic spectral features, observing a very strong modulation of the photocurrent, which even undergoes a change in sign when the Fermi level crosses the charge neutrality point. Our results demonstrate the unexploited potential of low-temperature photocurrent spectroscopy for studying excitons in low-dimensional materials, and provide new insight into excitonic transitions in 1L-MoSe2.

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Fu, Xiaqing, Zirui Qiao, Hangyu Zhou, and Dan Xie. "Defect Engineering in Transition Metal Dichalcogenide-Based Gas Sensors." Chemosensors 12, no. 6 (May 21, 2024): 85. http://dx.doi.org/10.3390/chemosensors12060085.

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Since the discovery of innovative two-dimensional (2D) materials, significant efforts have been dedicated to exploring their intriguing properties and emerging applications. Among all candidates, transition metal dichalcogenides (TMDs) have proven to be exceptional for gas sensing, while defects engineering has been introduced to modify the pristine TMDs for better gas sensing performances. In this review, we systematically summarize types of defects, advanced characterization techniques, and state-of-the-art controllable synthetic methods. Various types of defects in TMDs can induce diverse changes in chemical and electron structures, which are closely correlated with gas sensing ability. Therefore, connections between defects and gas sensing mechanisms and performances have been addressed based on both defect categories and electron affinity of gases. This review will be a guide for researchers in defective materials and open up the field of precisely synthesis chemistry and deepen the understanding of the underlying effects of defects in other 2D materials.

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Yang, Yang, Yongping Han, and Renfei Li. "Raman Studies of Two-Dimensional Group-VI Transition Metal Dichalcogenides under Extreme Conditions." Crystals 13, no. 6 (June 9, 2023): 929. http://dx.doi.org/10.3390/cryst13060929.

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In the past decade, two-dimensional (2D) transition metal dichalcogenides (TMDs) have attracted increasing attention because of their striking physical properties and extensive applicability. Meanwhile, Raman spectroscopy has been demonstrated to be a feasible tool and is extensively employed in research on 2D TMDs. In recent years, the deployment of Raman spectroscopy under extreme conditions has elucidated the physical properties of TMDs. In this review, we focus on the extreme-condition Raman spectroscopy of typical group-VI TMDs, which are classified and discussed under the three extreme conditions of low temperature, high pressure and high magnetic field. The conclusion presents the most pressing challenges and attractive future opportunities in this rapidly developing research field.

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Cho, Suyeon. "(Invited) Engineering Active Sites of 2D Materials for Active Hydrogen Evolution Reaction." ECS Meeting Abstracts MA2024-02, no. 35 (November 22, 2024): 2487. https://doi.org/10.1149/ma2024-02352487mtgabs.

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Hydrogen evolution reaction (HER) is a promising solution for sustainable and clean energy source with zero carbon emission. Numerous studies have been conducted with versatile low dimensional materials, and the development of highly active electrochemical catalysts for HER has been one of the most important applications of the materials in the studies. Despite such extensive research, the physical origin of active catalytic performances from low dimensional materials remains unclear, which is distinguished from classical transition metal-based catalysts. Here, we review recent studies on intrinsic catalytic activity of two-dimensional (2D) semimetals, particularly among transition metal dichalcogenides (TMDs), highlighting promising strategies for the design of materials to further enhance their catalytic performances. An attractive approach for active HER is fabricating single-atom catalysts in the framework of TMDs. While electrochemical reaction at a catalytic atom for hydrogen evolution has been discussed by the Sabatier principle, we describe the phenomenon by Gibbs free energy for hydrogen adsorption via down-sizing, alloying, hybridizing, hetero-structuring, and phase boundary engineering mostly with TMDs. Thus, unique advantage of TMDs and their derivatives for HER are summarized, proposing research directions for promising design of low dimensional electrochemical catalysts for efficient HER and their energy applications.

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Cao, Jiangming, Michael P. Mercer, Andrea Silva, and Denis Kramer. "First Principles Calculation of Sodium Intercalation in Transition-Metal Dichalcogenides." ECS Meeting Abstracts MA2024-02, no. 9 (November 22, 2024): 1366. https://doi.org/10.1149/ma2024-0291366mtgabs.

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Sodium ion batteries (SIBs) are an attractive substitute to lithium ion batteries, particularly for grid-scale energy storage, due to low cost and abundance of sodium [1]. Two-dimensional (2D) transition-metal dichalcogenides (TMDs) have evoked widespread attention as promising electrode materials [2], particularly as potential anode materials. Based on a database of 2D-TMDs, there is a need to determine the stability of 3D-TMDs before/after sodiation to optimise SIB anode materials. In this work, using density functional theory (DFT) calculations, we conduct a systematic study of the series of TMDs for their electrochemical performance and structural properties based on 2D ground state structure of TMDs [3,4]. A voltage map is presented where the sodiated voltage of 3D-TMDs can be consulted, including p-MoS2, p-CdI2, p-NbTe2, p-WTe2, p-PdS2 and p-PdCl2 prototypes. With this voltage map, we can explore which TMDs can be as a suitable electrode materials for SIBs. Group VI elements (Mo, W) emerge as promising candidate from the voltage map. Further exploration of these candidates reveals that a prismatic → octahedral phase transition occurred during sodiation for CrS2, MoS2, CrSe2 and WS2, while MoSe2 and WSe2 show low voltage in prismatic coordination without phase transition. Some of Mo and W systems appearing to be promising anode materials because of relatively low voltage. However, phase transition during sodiation of CrS2, MoS2, CrSe2 and WS2 leads to an increase in voltage, making these less effective as anode materials.Additionally, the phase changes could be associated with other detrimental volume changes, hysteresis and possible degradation issues. Keywords: transition-metal dichalcogenides, sodium-ion batteries, phase transition during sodiation, first principles calculation. Reference [1] Kundu, D., Talaie, E., Duffort, V. & Nazar, L. F. The emerging chemistry of sodium ion batteries for electrochemical energy storage. Angewandte Chemie - International Edition 54, 3432–3448 (2015). [2] J Morales, J Santos, and J L Tirado. Electrochemical studies of lithium and sodium intercalation in MoSe2. Solid State Ionics, 83:57–64, 1996. [3] Andrea Silva, Jiangming Cao, Tomas Polcar, and Denis Kramer. Design guidelines for two-dimensional transition metal dichalcogenide alloys. Chemistry of Materials, 34:10279–10290, 2022. [4] Andrea Silva, Jiangming Cao, Tomas Polcar, and Denis Kramer. Pettifor maps of complex ternary two-dimensional transition metal sulfides. npj Computational Materials, 8(1):178, 2022.

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Choi, Woosuk, Muhammad Arslan Shehzad, Sanghoon Park, and Yongho Seo. "Influence of removing PMMA residues on surface of CVD graphene using a contact-mode atomic force microscope." RSC Advances 7, no. 12 (2017): 6943–49. http://dx.doi.org/10.1039/c6ra27436f.

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Liu, Hongsheng, Nannan Han, and Jijun Zhao. "Atomistic insight into the oxidation of monolayer transition metal dichalcogenides: from structures to electronic properties." RSC Advances 5, no. 23 (2015): 17572–81. http://dx.doi.org/10.1039/c4ra17320a.

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Chueh, Yu-Lun. "Design of Innovative Janus Phase/Structure-Engineered Two-Dimensional Layered Heterostructures with Enhanced Catalysis Effect on Green Energy Applications." ECS Meeting Abstracts MA2024-02, no. 39 (November 22, 2024): 2614. https://doi.org/10.1149/ma2024-02392614mtgabs.

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A new class of two-dimensional (2D) materials called Janus TMDs have sparked research interest in recent years due to their myriad of possible applications, which include photocatalysis, optoelectronics, valleytronics, water splitting, and sensing, among others. Compared to traditional TMDs, Janus TMDs are composed of different chalcogen atoms, which breaks the out-of-plane symmetry. The asymmetrical structure, like in Janus MoSSe, generates out-of-plane dipoles between the top Se and bottom S atoms. This intrinsic dipole moment contributes to efficient charge separation, enhancement of Raman scattering and large Rashba splitting. Unlike conventional 2D materials, Janus TMDs do not exist in nature and have only been fabricated synthetically from a parent TMD (e.g., MoS2 or WS2). The fabrication techniques for synthesizing Janus TMDs require extreme precision to obtain high-quality flakes and avoid alloying or randomized orientation distribution of chalcogen atoms. An inductively coupled plasma (ICP) was used to synthesize Transition Metal Dichalcogenides (TMDs) through a plasma-assisted selenization process of metal oxide (MOx) at a low temperature. Compared to other CVD processes, ICP facilitates the decomposition of the precursors at lower temperatures. Here, we designed innovative Janus phase/structure-engineered two-dimensional layered heterostructures with enhanced catalysis effect on green energy applications derived from the MOx 3D-hierarchical nanostructures through a low-temperature plasma-assisted selenization process. The applications, including the catalysis effect for water splitting, nitrogen reduction, and battery, will be reported.

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Nies, Cara-Lena, and Michael Nolan. "Study of Cu, Co and Ru Nanoclusters on MoS₂ to Predict Thin Film Morphology." ECS Meeting Abstracts MA2022-01, no. 12 (July 7, 2022): 848. http://dx.doi.org/10.1149/ma2022-0112848mtgabs.

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Interfaces of 2D materials with metals are of interest for a large variety of applications, including sensors, batteries, catalysis, electronics, and semi-conductor devices. Transition metal dichalcogenides (TMDs) and specifically MoS2 are some of the most widely studied 2D materials. A detailed understanding of the interactions of metals with 2D TMDs can give useful insights into possible applications for metal-TMD systems. However, the literature focuses mainly on comparing trends in single atom adsorption and studying nanoparticles on MoS2 monolayers. In this work we aim to increase the understanding of metal-MoS2 interactions and metal nucleation on TMDs. We use density functional theory (DFT) to study the adsorption of small metal clusters with up to four atoms on MoS2 monolayers. Insights gained from this work allow us to understand the initial nucleation of metal thin films on TMDs as well as predict the likely morphology of the thin film as it grows. The metals studied are Cu, Co and Ru, which are chosen for their range of applications, particularly in electronics. Metal-substrate interactions, preferred adsorption modes and stable nanocluster geometries are presented on pristine MoS2 and in the presence of the readily formed sulfur vacancy. The strength of interaction between the metals and MoS2 is in the order Co > Ru > Cu. Metal-substrate interactions are localised to the adsorption site; however we find that both Ru and Co can induce formation of sulfur vacancies through the formation of the corresponding metal sulfide.

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Ullah, Nabi, Dariusz Guziejewski, Aihua Yuan, and Sayyar Ali Shah. "Recent Advancement and Structural Engineering in Transition Metal Dichalcogenides for Alkali Metal Ions Batteries." Materials 16, no. 7 (March 23, 2023): 2559. http://dx.doi.org/10.3390/ma16072559.

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Currently, transition metal dichalcogenides-based alkaline metal ion batteries have been extensively investigated for renewable energy applications to overcome the energy crisis and environmental pollution. The layered morphologys with a large surface area favors high electrochemical properties. Thermal stability, mechanical structural stability, and high conductivity are the primary features of layered transition metal dichalcogenides (L-TMDs). L-TMDs are used as battery materials and as supporters for other active materials. However, these materials still face aggregation, which reduces their applicability in batteries. In this review, a comprehensive study has been undertaken on recent advancements in L-TMDs-based materials, including 0D, 1D, 2D, 3D, and other carbon materials. Types of structural engineering, such as interlayer spacing, surface defects, phase control, heteroatom doping, and alloying, have been summarized. The synthetic strategy of structural engineering and its effects have been deeply discussed. Lithium- and sodium-ion battery applications have been summarized in this study. This is the first review article to summarize different morphology-based TMDs with their intrinsic properties for alkali metal ion batteries (AMIBs), so it is believed that this review article will improve overall knowledge of TMDs for AMIBS applications.

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Lu, Song, Fengliu Lou, and Zhixin Yu. "Recent Progress in Two-Dimensional Materials for Electrocatalytic CO2 Reduction." Catalysts 12, no. 2 (February 17, 2022): 228. http://dx.doi.org/10.3390/catal12020228.

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Electrocatalytic CO2 reduction (ECR) is an attractive approach to convert atmospheric CO2 to value-added chemicals and fuels. However, this process is still hindered by sluggish CO2 reaction kinetics and the lack of efficient electrocatalysts. Therefore, new strategies for electrocatalyst design should be developed to solve these problems. Two-dimensional (2D) materials possess great potential in ECR because of their unique electronic and structural properties, excellent electrical conductivity, high atomic utilization and high specific surface area. In this review, we summarize the recent progress on 2D electrocatalysts applied in ECR. We first give a brief description of ECR fundamentals and then discuss in detail the development of different types of 2D electrocatalysts for ECR, including metal, graphene-based materials, transition metal dichalcogenides (TMDs), metal–organic frameworks (MOFs), metal oxide nanosheets and 2D materials incorporated with single atoms as single-atom catalysts (SACs). Metals, such as Ag, Cu, Au, Pt and Pd, graphene-based materials, metal-doped nitric carbide, TMDs and MOFs can mostly only produce CO with a Faradic efficiencies (FE) of 80~90%. Particularly, SACs can exhibit FEs of CO higher than 90%. Metal oxides and graphene-based materials can produce HCOOH, but the FEs are generally lower than that of CO. Only Cu-based materials can produce high carbon products such as C2H4 but they have low product selectivity. It was proposed that the design and synthesis of novel 2D materials for ECR should be based on thorough understanding of the reaction mechanism through combined theoretical prediction with experimental study, especially in situ characterization techniques. The gap between laboratory synthesis and large-scale production of 2D materials also needs to be closed for commercial applications.

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Yan, Yalan, Shuang Ding, Xiaonan Wu, Jian Zhu, Dengman Feng, Xiaodong Yang, and Fangfei Li. "Tuning the physical properties of ultrathin transition-metal dichalcogenides via strain engineering." RSC Advances 10, no. 65 (2020): 39455–67. http://dx.doi.org/10.1039/d0ra07288e.

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Transition-metal dichalcogenides (TMDs) have become one of the recent frontiers and focuses in two-dimensional (2D) materials fields thanks to their superior electronic, optical, and photoelectric properties.

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Zhao, Qiyi, Yaohui Guo, Yixuan Zhou, Zehan Yao, Zhaoyu Ren, Jintao Bai, and Xinlong Xu. "Band alignments and heterostructures of monolayer transition metal trichalcogenides MX3 (M = Zr, Hf; X = S, Se) and dichalcogenides MX2 (M = Tc, Re; X=S, Se) for solar applications." Nanoscale 10, no. 7 (2018): 3547–55. http://dx.doi.org/10.1039/c7nr08413g.

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The band gaps and work functions of monolayer IVB-VIA 2D TMTs MX₃ and VIIB-VIA 2D TMDs MX₂ are calculated and their band alignments and the relevant physical origins of the band alignments are investigated.

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Ejeromedoghene, Onome, Mary Nnyia, Charles Okoye, Abiodun Oladipo, and Ebube Anyaebosim. "Environmental Decontamination Using Transition Metal Dichalcogenides Based Materials: A Review." Journal of Materials & Environmental Sustainability Research 2, no. 1 (March 7, 2022): 1–18. http://dx.doi.org/10.55455/jmesr.2022.001.

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The frequent release of toxic compounds into the environment has caused substantial pollution of different aspects of the ecosystem. Thus, the need for suitable materials for environmental remediation is in high demand. Although many 2D materials with remarkable properties have been synthesized for the remediation of toxic pollutants of organic and inorganic origin, transition metal dichalcogenides (TMDs) have gathered extensive recognition lately, owing to their intriguing photocatalytic properties and tunable functionality that offers promising prospects for the decontamination, degradation, adsorption, and removal of these toxic pollutants. Therefore, this review provides the recent advancement of photocatalytic TMDs and the mechanism of their performance towards environmental remediation. Also, insights on new perspectives were highlighted.

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Hu, Yaowu, Feng Zhang, Michael Titze, Biwei Deng, Hebin Li, and Gary J. Cheng. "Straining effects in MoS2 monolayer on nanostructured substrates: temperature-dependent photoluminescence and exciton dynamics." Nanoscale 10, no. 12 (2018): 5717–24. http://dx.doi.org/10.1039/c8nr00332g.

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Stylianakis, Minas M. "Optoelectronic Nanodevices." Nanomaterials 10, no. 3 (March 13, 2020): 520. http://dx.doi.org/10.3390/nano10030520.

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Over the last decade, novel materials such as graphene derivatives, transition metal dichalcogenides (TMDs), other two-dimensional (2D) layered materials, perovskites, as well as metal oxides and other metal nanostructures have centralized the interest of the scientific community [...]

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Zhang, Lili, Chenyu Wang, Xue-Lu Liu, Tao Xu, Mingsheng Long, Erfu Liu, Chen Pan, et al. "Damage-free and rapid transfer of CVD-grown two-dimensional transition metal dichalcogenides by dissolving sacrificial water-soluble layers." Nanoscale 9, no. 48 (2017): 19124–30. http://dx.doi.org/10.1039/c7nr06928f.

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As one of the most important family members of two-dimensional (2D) materials, the growth and damage-free transfer of transition metal dichalcogenides (TMDs) play crucial roles in their future applications.

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Jin, Hao, Tao Wang, Zhi-Rui Gong, Chen Long, and Ying Dai. "Prediction of an extremely long exciton lifetime in a Janus-MoSTe monolayer." Nanoscale 10, no. 41 (2018): 19310–15. http://dx.doi.org/10.1039/c8nr04568b.

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Dai, Wenyang. "Two-Dimensional Materials in Nanomaterials: Properties, Applications, and Prospects." Applied and Computational Engineering 89, no. 1 (September 10, 2024): 87–92. http://dx.doi.org/10.54254/2755-2721/89/20241095.

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Recently, two-dimensional (2D) materials have garnered significant attention in nanomaterials research because of their unique physical and chemical properties. This paper examines the research background, core properties, main application areas, and future prospects of 2D materials. Through a systematic literature review and case studies, this paper summarizes the main advances and challenges in current 2D material research. The research methodology includes a literature review and case study analysis, aiming to uncover the potential of 2D materials in nanoelectronics, optoelectronic devices, energy storage, and biomedicine. The research questions address the fundamental properties of 2D materials, their practical applications, and strategies to overcome existing challenges. The results indicate that while 2D materials like graphene and transition metal dichalcogenides (TMDs) exhibit excellent electronic, optical, and mechanical properties, they still encounter significant challenges in material preparation, performance tuning, and environmental safety. This paper proposes potential solutions and predicts the future applications of 2D materials in emerging technologies. The conclusion asserts that with the continuous discovery of novel 2D materials and technological advancements, 2D materials will play a crucial role in science and industry.

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Adilbekova, Begimai, Yuanbao Lin, Emre Yengel, Hendrik Faber, George Harrison, Yuliar Firdaus, Abdulrahman El-Labban, Dalaver H. Anjum, Vincent Tung, and Thomas D. Anthopoulos. "Liquid phase exfoliation of MoS2 and WS2 in aqueous ammonia and their application in highly efficient organic solar cells." Journal of Materials Chemistry C 8, no. 15 (2020): 5259–64. http://dx.doi.org/10.1039/d0tc00659a.

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Simple, scalable and cost-effective synthesis of quality two-dimensional (2D) transition metal dichalcogenides (TMDs) is critical for fundamental investigations but also for the widespread adoption of these low-dimensional materials in an expanding range of device applications.

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Song, Zhifan, Zumin Wang, and Ranbo Yu. "Strategies for Advanced Supercapacitors Based on 2D Transition Metal Dichalcogenides: From Material Design to Device Setup." Small Methods, September 22, 2023. http://dx.doi.org/10.1002/smtd.202300808.

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AbstractRecently, the development of new materials and devices has become the main research focus in the field of energy. Supercapacitors (SCs) have attracted significant attention due to their high power density, fast charge/discharge rate, and excellent cycling stability. With a lamellar structure, 2D transition metal dichalcogenides (2D TMDs) emerge as electrode materials for SCs. Although many 2D TMDs with excellent energy storage capability have been reported, further optimization of electrode materials and devices is still needed for competitive electrochemical performance. Previous reviews have focused on the performance of 2D TMDs as electrode materials in SCs, especially on their modification. Herein, the effects of element doping, morphology, structure and phase, composite, hybrid configuration, and electrolyte are emphatically discussed on the overall performance of 2D TMDs‐based SCs from the perspective of device optimization. Finally, the opportunities and challenges of 2D TMDs‐based SCs in the field are highlighted, and personal perspectives on methods and ideas for high‐performance energy storage devices are provided.

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Koh, See Wee, Jie Hu, Jeemin Hwang, Peng Yu, Zixu Sun, Qiunan Liu, Hong Wei, et al. "Two-Dimensional Palladium Diselenide for Oxygen Reduction Reaction." Materials Chemistry Frontiers, 2021. http://dx.doi.org/10.1039/d0qm01113d.

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The emerging two-dimensional (2D) materials, particularly 2D transition metal dichalcogenides (TMDs), show great potential for catalysis due to their extraordinary large surface areas and tunable activities. However, the as-synthesized TMDs...

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Zhou, Guigang, Jinsheng Ji, Ziling Chen, Jing Shuai, Qijie Liang, and Qian Zhang. "Scalable Electronic and Optoelectronic Devices Based on 2D TMDs." Materials Futures, September 18, 2024. http://dx.doi.org/10.1088/2752-5724/ad7c6c.

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Abstract Materials are the building blocks of various functional applications. With Moore's Law approaching Si’s physical limits, traditional semiconductor-based monolithic three-dimentional (M3D) integrated circuits always suffer from the issues, including electrical performance (carrier scattering), chip-overheating (low heat conductivity), electromagnetic interference. Recently, two-dimensional transition metal dichalcogenides (2D TMDs) inherit the atomically-thin thickness of 2D materials and exhibit outstanding natures, such as smooth flatness (excellent compatibility), electronic property (thickness below 1 nm), absence of dangling bonds (decreasing carrier scattering), making them highly promising for next-generation functional devices in comparison with traditional bulk materials. Up to now, 2D TMD-based transistors have already exhibited the feasibility of replacing conventional one in terms of performances. Furthermore, the technology of large-area 2D TMDs films has been greatly successful, which lays the foundation for the fabrication of scalable 2D TMD-based devices. Besides, the scalable devices based on 2D TMDs also show the prospects of realizing ultra-high-density M3D integrated circuits owing to the presence of outstanding compatibility. Herein, we focus some thriving research areas and provide a systematic review of recent advances in the field of scalable electronic and optoelectronic devices based on 2D TMDs, including large-area synthesis, property modulation, large-scale device applications, and multifunctional device integration. The research in 2D TMDs has clearly exhibited the tremendous promise for scalable diversified applications. In addition, scalable 2D TMD-based devices in terms of mass production, controllability, reproducibility, and low-cost have also been highlighted, showing the importance and benefits in modern industry. Finally, we summarize the remaining challenges and discuss the future directions of scalable 2D TMDs devices. Finally, we summarize the remaining challenges and discuss the future directions of scalable 2D TMDs devices.

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Liu, Ming‐Jin, Shin‐Yi Tang, Ruei‐Hong Cyu, Chia‐Chen Chung, Yu‐Ren Peng, Pei‐Jung Yang, and Yu‐Lun Chueh. "Two‐Dimensional Transition Metal Dichalcogenides (2D TMDs) Coupled With Zero‐Dimensional Nanomaterials (0D NMs) for Advanced Photodetection." Small Methods, December 15, 2024. https://doi.org/10.1002/smtd.202401240.

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AbstractThe integration of 2D transition metal dichalcogenides (TMDs) with other materials presents a promising approach to overcome inherent limitations and enable the development of novel functionalities. In particular, 0D nanomaterials (0D NMs) offer notable advantages for photodetection, including broadband light absorption, size‐dependent optoelectronic properties, high quantum efficiency, and good compatibility. Herein, the integration of 0D NMs with 2D TMDs to develop high‐performance photodetectors is reviewed. The review provides a comprehensive overview of different types of 0D NMs, including plasma nanoparticles (NPs), up‐conversion NPs, quantum dots (QDs), nanocrystals (NCs), and small molecules. The discussion starts with an analysis of the mechanism of 0D NMs on 2D TMDs in photodetection, exploring various strategies for improving the performance of hybrid 2D TMDs/0D NMs. Recent advancements in photodetectors combining 2D TMDs with 0D NMs are investigated, particularly emphasizing critical factors such as photosensitivity, photogain, specific detectivity, and photoresponse speed. The review concludes with a summary of the current status, highlighting the existing challenges and prospective developments in the advancement of 0D NMs/2D TMDs‐based photodetectors.

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Hakami, Mariam, Chien-Chih Tseng, Kohei Nanjo, Vincent Tung, and Jui-Han Fu. "Wafer-scale epitaxy of transition-metal dichalcogenides with continuous single-crystallinity and engineered defect density." MRS Bulletin, September 28, 2023. http://dx.doi.org/10.1557/s43577-023-00598-1.

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AbstractResearch on electronic channel materials has traditionally focused on bulk and nanocrystals, nanowires, and nanotubes. However, the recent surge of interest in two-dimensional (2D) transition-metal dichalcogenides (TMDs) has emerged as a game-changer in this field. The atomically thin structure of 2D TMDs offers unique electronic and optical properties, which have been shown to have significant potential in various applications, such as optoelectronics, energy harvesting, and spintronics. Epitaxy growth of single-crystal 2D TMDs on oxide or metallic substrates has opened up new opportunities for direct integration into existing manufacturing pathways. In this article, we discuss recent advances in achieving continuous single-crystallinity of 2D TMDs on oxide and metallic substrates by controlling the nucleation and growth rate of crystalline domains. We also review strategies for the controlled introduction of defects through postgrowth processing and substrate engineering. Finally, we highlight emerging strategies, new opportunities, and remaining challenges for bridging the gap between lab innovations and commercialization. The ability to grow high-quality 2D TMDs on scalable and industry-compatible substrates represents a significant breakthrough in the field of electronic materials and has the potential to revolutionize the semiconductor industry. Despite the remaining challenges, the future of 2D TMDs looks promising. Their integration into existing manufacturing pathways could open up new avenues for advanced electronic devices with improved performance and reduced power consumption. Graphical abstract

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Luo, Ruichun, Meng Gao, Chunwen Wang, Juntong Zhu, Roger Guzman, and Wu Zhou. "Probing Functional Structures, Defects, and Interfaces of 2D Transition Metal Dichalcogenides by Electron Microscopy." Advanced Functional Materials, October 2, 2023. http://dx.doi.org/10.1002/adfm.202307625.

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Abstract2D transition metal dichalcogenides (TMDs) exhibit remarkable properties that are strongly influenced by their atomic structures, as well as by various types of defects and interfaces that can be precisely engineered and controlled. These features make 2D TMDs and TMD‐based materials highly promising for a wide range of applications in electronics, optoelectronics, magnetism, spintronics, catalysis, energy, etc. By providing a comprehensive approach to understand the structure–property–functionality relationship in materials at the atomic scale, electron microscopy, and spectroscopy techniques have emerged as invaluable tools for studying both the static characteristics and dynamic evolutions of 2D TMDs. In this review, the primary focus lies in exploring intrinsic and artificial structures in TMDs and their heterostructures, along with their corresponding properties, through cutting‐edge aberration‐corrected scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS). Additionally, recent advancements in the field of in situ visualization and manipulation of 2D TMDs using electron beams are highlighted. It is anticipated that the up‐to‐date overview provided, along with a glimpse into the future development of STEM‐based techniques, will make a substantial contribution to advancing research on 2D materials.

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Feng, Lan, Dan Zhao, Jian Yu, Qian Zhao, Xiaoyan Yuan, Yi Liu, and Shouwu Guo. "Two-dimensional transition metal dichalcogenides based composites for microwave absorption applications: a review." Journal of Physics: Energy, November 2, 2022. http://dx.doi.org/10.1088/2515-7655/ac9f6b.

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Abstract Two-dimensional structural transition metal dichalcogenides (2D TMDs) have the advantages of superb thermal and chemical stability, distinctive layered structures, and ultrathin thicknesses, which make them potential candidates in the microwave absorption field. The recent progress in 2D TMDs and their composite nanomaterials with enhanced microwave absorption performance are reviewed here. The synthesis methods, and the microwave absorption properties, including the maximum reflection loss (RL) value and effective absorption bandwidth (EAB) of various 2D TMD nanocomposites, are described in detail. Furthermore, the current challenges and future prospects for the development of 2D TMDs are raised.

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Kim, Jun Young, Łukasz Gelczuk, Maciej P. Polak, Daria Hlushchenko, Dane Morgan, Robert Kudrawiec, and Izabela Szlufarska. "Experimental and theoretical studies of native deep-level defects in transition metal dichalcogenides." npj 2D Materials and Applications 6, no. 1 (October 29, 2022). http://dx.doi.org/10.1038/s41699-022-00350-4.

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AbstractTransition metal dichalcogenides (TMDs), especially in two-dimensional (2D) form, exhibit many properties desirable for device applications. However, device performance can be hindered by the presence of defects. Here, we combine state of the art experimental and computational approaches to determine formation energies and charge transition levels of defects in bulk and 2D MX2 (M = Mo or W; X = S, Se, or Te). We perform deep level transient spectroscopy (DLTS) measurements of bulk TMDs. Simultaneously, we calculate formation energies and defect levels of all native point defects, which enable identification of levels observed in DLTS and extend our calculations to vacancies in 2D TMDs, for which DLTS is challenging. We find that reduction of dimensionality of TMDs to 2D has a significant impact on defect properties. This finding may explain differences in optical properties of 2D TMDs synthesized with different methods and lays foundation for future developments of more efficient TMD-based devices.

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Jia, Yanyu, Guo Yu, Tiancheng Song, Fang Yuan, Ayelet J Uzan, Yue Tang, Pengjie Wang, et al. "Superconductivity from On-Chip Metallization on 2D Topological Chalcogenides." Physical Review X 14, no. 2 (June 21, 2024). http://dx.doi.org/10.1103/physrevx.14.021051.

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Two-dimensional (2D) transition metal dichalcogenides (TMDs) is a versatile class of quantum materials of interest to various fields including, e.g., nanoelectronics, optical devices, and topological and correlated quantum matter. Tailoring the electronic properties of TMDs is essential to their applications in many directions. Here, we report that a highly controllable and uniform on-chip 2D metallization process converts a class of atomically thin TMDs into robust superconductors, a property belonging to none of the starting materials. As examples, we demonstrate the introduction of superconductivity into a class of 2D air-sensitive topological TMDs, including monolayers of Td−WTe2, 1T′−MoTe2, and 2H−MoTe2, as well as their natural and twisted bilayers, metallized with an ultrathin layer of palladium. This class of TMDs is known to exhibit intriguing topological phases ranging from topological insulator, Weyl semimetal to fractional Chern insulator. The unique, high-quality two-dimensional metallization process is based on our recent findings of the long-distance, non-Fickian in-plane mass transport and chemistry in 2D that occur at relatively low temperatures and in devices fully encapsulated with inert insulating layers. Highly compatible with existing nanofabrication techniques for van der Waals stacks, our results offer a route to designing and engineering superconductivity and topological phases in a class of correlated 2D materials. Published by the American Physical Society 2024

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Zhou, Wei, Huimin Gong, Xiaohe Jin, Yang Chen, Huimin Li, and Song Liu. "Recent Progress of Two-Dimensional Transition Metal Dichalcogenides for Thermoelectric Applications." Frontiers in Physics 10 (March 11, 2022). http://dx.doi.org/10.3389/fphy.2022.842789.

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Two-dimensional transition metal dichalcogenides (2D-TMDs) have sparked immense interest, resulting from their unique structural, electronic, mechanical, and thermal properties. The band structures, effective mass, electron mobility, valley degeneracy, and the interactions between phonons and heat transport properties in 2D-TMDs can be efficiently tuned via various approaches. Moreover, the interdependent electrical and thermal conductivity can be modulated independently to facilitate the thermoelectric (TE)-based energy conversion process, which enables optimization of TE properties and promising TE applications. This article briefly reviews the recent development of TE properties in 2D-TMDs. First, the advantages of 2D-TMDs for TE applications are introduced. Then, the manipulations of electrical and thermal transport in 2D-TMDs are briefly discussed, including various influencing factors such as thickness effect, structural defects, and mechanical strain. Finally, the recent advances in the study of electrical, thermal transport, and TE properties of 2D-TMDs, TE-related applications, the challenges, and the future prospects in this field are reviewed.

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Feng, Xiaojing, Zhiqi Li, Guangda Chen, Haoyu Yue, Yan Gao, Xiankun Zhang, Zhongnan Guo, and Wenxia Yuan. "Single crystal growth of layered metallic materials TiTe₂ based on a polytelluride flux method." CrystEngComm, 2023. http://dx.doi.org/10.1039/d3ce00619k.

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Layered metallic transition metal dichalcogenides (TMDs) with bonding-free surfaces and weak Fermi-level pinning properties have exhibited potential application as electrode materials in two-dimensional (2D) semiconductor devices. However, various TMDs metallic...

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46

Zheng, Huanhuan, Bingqiang Niu, Yijin Wang, Hafiz Muhammad Asif Javed, Peng Zhong, and Xiaohua Ma. "Two-dimensional transitional metal disulfides as charge transport layers in organic-inorganic perovskite solar cells." Recent Patents on Nanotechnology 14 (December 23, 2020). http://dx.doi.org/10.2174/1872210514666201223093838.

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: In the past decade, organic-inorganic perovskite solar cells (PSCs) have received great attentions due to their high efficiencies and low costs. However, the commercialization of PSCs is stilled hindered by several issues such as device performance (especially for large-area cells) and stability. Recently, two-dimensional (2D) transition metal disulfides (TMDs) show great potentials in solving aforementioned problems due to their unique morphological structure and electrical properties. Herein, we summarize the advancements in the recent applications of various TMDs materials as charge transport layers in PSCs. Although some progresses have been made, there are considerable issues to be tackled in this field. The challenges and development directions of these 2D TMDs materials for PSCs are also clarified. Lastly, the most recent advancements about TMDs materials in some other electronic (or optoelectronic) fields are also summarized and discussed.

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Tang, Xiao, Qi Hao, Xiangyu Hou, Leilei Lan, Mingze Li, Lei Yao, Xing Zhao, Zhenhua Ni, Xingce Fan, and Teng Qiu. "Exploring and Engineering 2D Transition Metal Dichalcogenides toward Ultimate SERS Performance." Advanced Materials, February 2024. http://dx.doi.org/10.1002/adma.202312348.

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AbstractSurface‐enhanced Raman spectroscopy (SERS) is an ultrasensitive surface analysis technique that is widely used in chemical sensing, bioanalysis, and environmental monitoring. The design of the SERS substrates is crucial for obtaining high‐quality SERS signals. Recently, two‐dimensional transition metal dichalcogenides (2D TMDs) have emerged as high‐performance SERS substrates due to their superior stability, ease of fabrication, biocompatibility, controllable doping, and tunable bandgaps and excitons. In this review, we provide a systematic overview of the latest advancements in 2D TMDs SERS substrates. This review comprehensively summarizes the candidate 2D TMDs SERS materials, elucidates their working principles for SERS, explores the strategies to optimize their SERS performance, and highlights their practical applications. We particularly delve into the material engineering strategies, including defect engineering, alloy engineering, thickness engineering, and heterojunction engineering. Additionally, we discuss the challenges and future prospects associated with the development of 2D TMDs SERS substrates, outlining potential directions that may lead to significant breakthroughs in practical applications.This article is protected by copyright. All rights reserved

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Kim, Brian S. Y., Tien Dat Ngo, Yasir Hassan, Sang Hoon Chae, Soon‐Gil Yoon, and Min Sup Choi. "Advances and Applications of Oxidized van der Waals Transition Metal Dichalcogenides." Advanced Science, September 23, 2024. http://dx.doi.org/10.1002/advs.202407175.

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AbstractThe surface oxidation of 2D transition metal dichalcogenides (TMDs) has recently gained tremendous technological and fundamental interest owing to the multi‐functional properties that the surface oxidized layer opens up. In particular, when integrated into other 2D materials in the form of van der Waals heterostructures, oxidized TMDs enable designer properties, including novel electronic states, engineered light‐matter interactions, and exceptional‐point singularities, among many others. Here, the evolving landscapes of the state‐of‐the‐art surface engineering technologies that enable controlled oxidation of TMDs down to the monolayer‐by‐monolayer limit are reviewed. Next, the use of oxidized TMDs in van der Waals heterostructures for different electronic and photonic device platforms, materials growth processes, engineering concepts, and synthesizing new condensed matter phenomena is discussed. Finally, challenges and outlook for future impact of oxidized TMDs in driving rapid advancements across various application fronts is discussed.

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Lin, Zaoyang, Sven Dekelver, Daire Cott, Benjamin Groven, Stefanie Sergeant, Thierry Conard, Xiangyu Wu, et al. "Impact of monolayer WS2 surface properties on the gate dielectrics formation by atomic layer deposition." Journal of Vacuum Science & Technology A 42, no. 6 (October 28, 2024). http://dx.doi.org/10.1116/6.0003894.

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Two-dimensional transition metal dichalcogenides (2D TMDs), such as MoS2 and WS2, have emerged as promising channel materials for future generation transistors. However, carbon-based surface contaminants pose a significant challenge in the formation of high-quality metal–oxide–semiconductor gate stacks for 2D TMDs. Carbon-based surface contaminants are known to be present even on directly grown 2D TMDs that have not been in contact with polymers. These organic contaminants affect precursor adsorption during atomic layer deposition (ALD) of gate dielectrics on 2D TMDs and as such the 2D-dielectric interface. This study examines the effectiveness of predeposition annealing in mitigating carbon-based contaminants while maintaining the integrity of a directly grown WS2 monolayer on a SiO2 substrate. We show that a WS2 monolayer on a SiO2/Si substrate remains stable during vacuum annealing at temperatures up to 400 °C. Water contact angle measurements and x-ray photoelectron spectroscopy confirm that the surface concentration of carbon starts to decrease at 150 °C. Thermal anneal improves the surface coverage of Al2O3 for both conventional chemisorption-based ALD and physisorbed-precursor-assisted ALD processes by facilitating more effective Al2O3 nucleation on the WS2 monolayer. The impact of predeposition anneal on the Al2O3 growth behavior in both processes can be explained by changes in surface contaminant levels. Our results underscore the importance of surface pretreatment in dielectric deposition on 2D TMDs and demonstrate that predeposition anneal is an effective method to enhance ALD-based dielectric deposition on directly grown 2D TMDs.

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Huang, Ziwei, Wei Deng, Zhengwei Zhang, Bei Zhao, Hongmei Zhang, Di Wang, Bailing Li, Miaomiao Liu, Ying Huangfu, and Xidong Duan. "Terminal Atom‐Controlled Etching of 2D‐TMDs." Advanced Materials, February 5, 2023, 2211252. http://dx.doi.org/10.1002/adma.202211252.

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Journal articles on the topic '2D-TMDs materials'

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