2D Materials最新文献

{"title":"Cross-dimensional valley excitons from Förster coupling in arbitrarily twisted stacks of monolayer semiconductors","authors":"C. Li, Wang Yao","doi":"10.1088/2053-1583/ad0403","DOIUrl":"https://doi.org/10.1088/2053-1583/ad0403","url":null,"abstract":"Abstract In stacks of transition metal dichalcogenide monolayers with arbitrary twisting angles, we explore a new class of bright excitons arising from the pronounced Förster coupling, whose dimensionality is tuned by its in-plane momentum. The low energy sector at small momenta is two-dimensional, featuring a Mexican Hat dispersion, while the high energy sector at larger momenta becomes three-dimensional (3D) with sizable group velocity both in-plane and out-of-plane. By choices of the spacer thickness, versatile surface or interface exciton modes localized at designated layers can emerge out of the cross-dimensional bulk dispersion for a topological origin, which can be mapped to the Su–Schrieffer–Heeger soliton. Moreover, step-edges in spacers can be exploited for engineering lateral interfaces to enable interlayer communication of the topological interface exciton. Combined with the polarization selection rule inherited from the monolayer building block, these exotic exciton properties open up new opportunities for multilayer design towards 3D integration of valley exciton optoelectronics.","PeriodicalId":6812,"journal":{"name":"2D Materials","volume":"51 11","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136233551","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"What governs the atomic structure of the interface between 2D transition metal dichalcogenides in lateral heterostructures?","authors":"Francis Davies, Kai Mehlich, Carsten Busse, Arkady V. Krasheninnikov","doi":"10.1088/2053-1583/ad00ca","DOIUrl":"https://doi.org/10.1088/2053-1583/ad00ca","url":null,"abstract":"Abstract The development of lateral heterostructures (LHs) based on two-dimensional (2D) materials with similar atomic structure but distinct electronic properties, such as transition metal dichalcogenides (TMDCs), opened a new route towards realisation of optoelectronic devices with unique characteristics. In contrast to van der Waals vertical heterostructures, the covalent bonding at the interface between subsystems in LHs is strong, such that the morphology of the interface, which can be coherent or contain dislocations, strongly affects the properties of the LH. We predict the atomic structure of the interface with account for the mismatch between the primitive cell sizes of the components, and more important, the widths of the joined materials using parameters derived from first-principles calculations. We apply this approach to a variety of TMDCs and set a theoretical limit on when the transition of the interface from coherent to dislocation-type should occur. We validate our theoretical results by comparison with the initial stage of two-dimensional heteropitaxial growth of junctions between MoS 2 and TaS 2 on Au(111).","PeriodicalId":6812,"journal":{"name":"2D Materials","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135667703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Graphdiyne (CnH2n-2) / NiWO4 self-assembled p-n junction characterized with in situ XPS for efficient photocatalytic hydrogen production","authors":"Linqing Zhang, Minjun Lei, zhiliang jin","doi":"10.1088/2053-1583/ad01c8","DOIUrl":"https://doi.org/10.1088/2053-1583/ad01c8","url":null,"abstract":"Abstract As is well known, how to deeply understand the charge separation and charge transfer capabilities of catalysts, as well as how to optimize these capabilities of catalysts to improve hydrogen production performance, remains a huge challenge. In recent years, a new type of carbon material graphdiyne (GDY) has been proposed. GDY acetylene has a special atomic arrangement that graphene does not have a two-dimensional network of sp 2 and sp conjugated intersections makes it easier to construct active sites and improve photocatalytic ability. In addition, GDY also has the advantage of adjusting the bandgap of other catalysts and inhibiting carrier recombination, making it more prone to hydrogen evolution reactions. In addition to using mechanical ball milling to produce GDY, NiWO 4 without precious metals was also prepared. The sheet-like structure of GDY in the composite catalyst provides a anchoring site and more active sites for the granular NiWO 4 . And the composite catalyst fully enhances the good conductivity of GDY and its unique ability to enhance electron transfer, greatly improving the ability of NiWO 4 as a single substance. Through in-situ x-ray photoelectron spectrometer, it was demonstrated that a p–n heterojunction was constructed between GDY and NiWO 4 in the composite catalyst, further enhancing the synergistic effect between the two, resulting in a hydrogen production rate of 90.92 μ mol for the composite catalyst is 4.56 times higher than that of GDY and 4.97 times higher than that of NiWO 4 , respectively, and the stability of the composite catalyst is significantly higher than that of each single catalyst.","PeriodicalId":6812,"journal":{"name":"2D Materials","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135824327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phonon-mediated magneto-resonances in biased graphene layers","authors":"mrityunjay pandey, Kenji Watanabe, Takashi Taniguchi, Srinivasan Raghavan, U. Chandni","doi":"10.1088/2053-1583/ad0401","DOIUrl":"https://doi.org/10.1088/2053-1583/ad0401","url":null,"abstract":"We explore the non-equilibrium transport regime in graphene using a large dc current in combination with a perpendicular magnetic field. The strong in-plane Hall field generated in the graphene channel results in Landau levels that are tilted spatially. The energy of cyclotron orbits in the bulk varies as a function of the spatial position of the guiding center, enabling us to observe a series of compelling features. While Shubnikov–de Haas oscillations are predictably suppressed in the presence of the Hall field, a set of fresh magneto resistance oscillations emerge near the charge neutrality point as a function of dc current. Two branches of oscillations with linear dispersions are evident as we vary carrier density and dc current, the velocities of which closely resemble the transverse acoustic (TA) and longitudinal acoustic (LA) phonon modes, suggestive of phonon-assisted intra-Landau level transitions between adjacent cyclotron orbits. Our results offer unique possibilities to explore non-equilibrium phenomena in two-dimensional materials and van der Waals heterostructures.","PeriodicalId":6812,"journal":{"name":"2D Materials","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135993896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Controllable growth of wafer-scale two-dimensional WS2 with outstanding optoelectronic properties","authors":"Shiwei Zhang, Yulong Hao, Fenglin Gao, Xiongqing Wu, Shijie Hao, Mengchun Qiu, Xiaoming Zheng, Yuehua Wei, Guolin Hao","doi":"10.1088/2053-1583/ad0404","DOIUrl":"https://doi.org/10.1088/2053-1583/ad0404","url":null,"abstract":"Abstract As one of two-dimensional (2D) semiconductor materials, transition metal dichalcogenides (TMDs) have sparked enormous potential in next-generation optoelectronics due to their unique and excellent physical, electronic and optical properties. Controllable growth of wafer-scale 2D TMDs is essential to realize various high-end applications, while it remains challenging. Herein, 2-inch 2D WS2 films were successfully synthesized by ambient pressure chemical vapor deposition based on substrate engineering and space-confined strategies. WS2 nucleation density can be effectively modulated depending on the annealing conditions of sapphire substrate. 2D WS2 films with controllable thickness can be fabricated by adjusting the space-confined height. Moreover, our strategies are demonstrated to be universal for the growth of other 2D TMD semiconductors. WS2-based photodetectors with different thicknesses were systematically investigated. Monolayer WS2 photodetector displays large responsivity of 0.355 A/W and high specific detectivity of 1.48 × 1011 Jones. Multilayer WS2 device exhibits negative self-powered photoresponse. Our work provides a new route for the synthesis of wafer-scale 2D TMD materials, paving the way for high performance integrated optoelectronic devices.
","PeriodicalId":6812,"journal":{"name":"2D Materials","volume":"61 30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135993882","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhancing pseudocapacitive intercalation in Ti3C2Tx MXene with molecular crowding electrolytes","authors":"Chaofan Chen, Albert de Kogel, Mark Weijers, Lars J. Bannenberg, Xuehang Wang","doi":"10.1088/2053-1583/acff08","DOIUrl":"https://doi.org/10.1088/2053-1583/acff08","url":null,"abstract":"Abstract The growing demand for safe, cost-efficient, high-energy and high-power electrochemical energy storage devices has stimulated the development of aqueous-based supercapacitors with high capacitance, high rate capability, and high voltage. 2D titanium carbide MXene-based electrodes have shown excellent rate capability in various dilute aqueous electrolytes, yet their potential window is usually narrower than 1.2 V. In this study, we show that the potential window of Ti 3 C 2 T x MXene can be efficiently widened to 1.5 V in a cost-effective and environmentally benign polyethylene glycol (PEG) containing molecular crowding electrolyte. Additionally, a pair of redox peaks at −0.25 V/−0.05 V vs. Ag (cathodic/anodic) emerged in cyclic voltammetry after the addition of PEG, yielding an additional 25% capacitance. Interestingly, we observed the co-insertion of the molecular crowding agent PEG-400 during the Li + intercalation process based on in-situ x-ray diffraction analysis. As a result, Ti 3 C 2 T x electrodes presented an interlayer space change of 4.7 Å during a complete charge/discharge cycle, which is the largest reversible interlayer space change reported so far for MXene-based electrodes. This work demonstrates the potential of adding molecular crowding agents to improve the performance of MXene electrodes in aqueous electrolytes and to enlarge the change of the interlayer spacing.","PeriodicalId":6812,"journal":{"name":"2D Materials","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135922862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Metal-metal bonding, electronic excitations, and strong resonance Raman effect in 2D layered α-MoCl3","authors":"Sandra Schiemenz, Samuel Froeschke, Marco Naumann, Marco Rosenkranz, Bernd Büchner, Andreas Koitzsch, Martin Knupfer, Silke Hampel, Stanislav M Avdoshenko, Alexey Popov","doi":"10.1088/2053-1583/ad024c","DOIUrl":"https://doi.org/10.1088/2053-1583/ad024c","url":null,"abstract":"Abstract Covalent bonding between transition metal atoms is a common phenomenon in honeycomb lattices of layered materials, which strongly affects their electronic and magnetic properties. This work presents a detailed spectroscopic study of α-MoCl3, 2D van der Waals material with covalently bonded Mo2 dimers, with a particular focus on the Mo–Mo bonding. Raman spectra of α-MoCl3 were studied with multiple excitation laser lines chosen in different parts of the absorption spectrum, while polarization measurements aided in the symmetry assignment of the observed modes. Furthermore, far-IR measurements and DFT phonon computations were performed to complete vibrational assignment. Polarized absorption, photoluminescence, and photoelectron spectroscopy supported by DFT calculations were employed to understand the consequences of the Mo–Mo bonding for the electronic structure and the localization/delocalization balance in d3–d3 interactions. A coupling of dimerization-related structural and electronic properties was revealed in the strong resonance Raman enhancement of the Mo–Mo stretching mode at 153 cm−1 when the excitation laser matched the electronic transition between σ-bonding and antibonding orbitals of the Mo2 dimer (σ→σ*). The deeper understanding of the metal-metal bonding and identification of the vibrational and electronic spectroscopic signatures of the dimerization will be of great use for the studies of electron delocalization in magnetic van der Waals materials.","PeriodicalId":6812,"journal":{"name":"2D Materials","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136062760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Strain-induced topological transitions and tilted Dirac cones in kagome lattices","authors":"Miguel Abraham Mojarro Ramirez, Sergio E Ulloa","doi":"10.1088/2053-1583/acfe88","DOIUrl":"https://doi.org/10.1088/2053-1583/acfe88","url":null,"abstract":"Abstract We study effects of strain on the electronic properties of the kagome lattice in a tight-binding formalism with spin–orbit coupling (SOC). The degeneracy at the Γ point evolves into a pair of emergent tilted Dirac cones under uniaxial strain, where the anisotropy and tilting of the bands depend on the magnitude and direction of the strain field. SOC opens gaps at the emergent Dirac points, making the flatband topological, characterized by a nontrivial <?CDATA $mathbb{Z}_2$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:msub> <mml:mrow> <mml:mi mathvariant=\"double-struck\">Z</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> </mml:math> index. Strains of a few percent drive the system into trivial or topological phases. This confirms that moderate strain can be used to engineer anisotropic Dirac bands with tunable properties to study new phases in kagome lattices.","PeriodicalId":6812,"journal":{"name":"2D Materials","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135302190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of the deposition process on the stability of Ti₃C₂T_<i>x</i> MXene films for bioelectronics.","authors":"Sneha Shankar, Brendan B Murphy, Nicolette Driscoll, Mikhail Shekhirev, Geetha Valurouthu, Kateryna Shevchuk, Mark Anayee, Francesca Cimino, Yury Gogotsi, Flavia Vitale","doi":"10.1088/2053-1583/ace26c","DOIUrl":"10.1088/2053-1583/ace26c","url":null,"abstract":"<p><p>Ti₃C₂T_<i>x</i> MXene is emerging as the enabling material in a broad range of wearable and implantable medical technologies, thanks to its outstanding electrical, electrochemical, and optoelectronic properties, and its compatibility with high-throughput solution-based processing. While the prevalence of Ti₃C₂T_<i>x</i> MXene in biomedical research, and in particular bioelectronics, has steadily increased, the long-term stability and degradation of Ti₃C₂T_<i>x</i> MXene films have not yet been thoroughly investigated, limiting its use for chronic applications. Here, we investigate the stability of Ti₃C₂T_<i>x</i> films and electrodes under environmental conditions that are relevant to medical and bioelectronic technologies: storage in ambient atmosphere (shelf-life), submersion in saline (akin to the <i>in vivo</i> environment), and storage in a desiccator (low-humidity). Furthermore, to evaluate the effect of the MXene deposition method and thickness on the film stability in the different conditions, we compare thin (25 nm), and thick (1.0 μm) films and electrodes fabricated via spray-coating and blade-coating. Our findings indicate that film processing method and thickness play a significant role in determining the long-term performance of Ti₃C₂T_<i>x</i> films and electrodes, with highly aligned, thick films from blade coating remarkably retaining their conductivity, electrochemical impedance, and morphological integrity even after 30 days in saline. Our extensive spectroscopic analysis reveals that the degradation of Ti₃C₂T_<i>x</i> films in high-humidity environments is primarily driven by moisture intercalation, ingress, and film delamination, with evidence of only minimal to moderate oxidation.</p>","PeriodicalId":6812,"journal":{"name":"2D Materials","volume":"10 4","pages":""},"PeriodicalIF":4.5,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10373437/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10276654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Temperature dependent temporal coherence of metallic-nanoparticle-induced single-photon emitters in a WSe₂ monolayer","authors":"Martin von Helversen, Lara Greten, Imad Limame, Ching-Wen Shih, Paul Schlaugat, Carlos Anton-Solanas, Christian Schneider, Bárbara Rosa, Andreas Knorr, Stephan Reitzenstein","doi":"10.1088/2053-1583/acfb20","DOIUrl":"https://doi.org/10.1088/2053-1583/acfb20","url":null,"abstract":"Abstract In recent years, much research has been undertaken to investigate the suitability of two-dimensional materials to act as single-photon sources with high optical and quantum optical quality. Amongst them, transition-metal dichalcogenides, especially WSe 2 , have been one of the subjects of intensive studies. Yet, their single-photon purity and photon indistinguishability remain the most significant challenges to compete with mature semiconducting systems such as self-assembled InGaAs quantum dots. In this work, we explore the emission properties of quantum emitters in a WSe 2 monolayer which are induced by metallic nanoparticles. Under quasi-resonant pulsed excitation, we verify clean single-photon emission with a g (2) (0) = 0.036 ± 0.004. Furthermore, we determine the temperature dependent coherence time via Michelson interferometry, where a value of (13.5 ± 1.0) ps is extracted for the zero-phonon line at 4 K, which reduces to (9 ± 2) ps at 8 K. Associated time-resolved photoluminescence experiments reveal a decrease of the decay time from (2.4 ± 0.1) ns to (0.42 ± 0.05) ns. This change in decay time is explained by a model which considers a Förster-type resonant energy transfer process which yields a strong temperature induced energy loss from the single-photon emitters to the nearby Ag nanoparticle.","PeriodicalId":6812,"journal":{"name":"2D Materials","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135131730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}