scholarly journals Observation of site-controlled localized charged excitons in CrI3/WSe2 heterostructures

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Arunabh Mukherjee ◽  
Kamran Shayan ◽  
Lizhong Li ◽  
Jie Shan ◽  
Kin Fai Mak ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Large Scale ◽  
Information Science ◽  
Van Der Waals ◽  
Spatial Location ◽  
Band Alignment ◽  
Tungsten Diselenide ◽  
Electrostatic Doping ◽  
Localized Excitons ◽  
Quantum Emitters

Abstract Isolated spins are the focus of intense scientific exploration due to their potential role as qubits for quantum information science. Optical access to single spins, demonstrated in III-V semiconducting quantum dots, has fueled research aimed at realizing quantum networks. More recently, quantum emitters in atomically thin materials such as tungsten diselenide have been demonstrated to host optically addressable single spins by means of electrostatic doping the localized excitons. Electrostatic doping is not the only route to charging localized quantum emitters and another path forward is through band structure engineering using van der Waals heterojunctions. Critical to this second approach is to interface tungsten diselenide with other van der Waals materials with relative band-alignments conducive to the phenomenon of charge transfer. In this work we show that the Type-II band-alignment between tungsten diselenide and chromium triiodide can be exploited to excite localized charged excitons in tungsten diselenide. Leveraging spin-dependent charge transfer in the device, we demonstrate spin selectivity in the preparation of the spin-valley state of localized single holes. Combined with the use of strain-inducing nanopillars to coordinate the spatial location of tungsten diselenide quantum emitters, we uncover the possibility of realizing large-scale deterministic arrays of optically addressable spin-valley holes in a solid state platform.

scholarly journals Electrical Control of Quantum Emitters in a Van der Waals Heterostructure

2021 ◽  
Author(s):  
Simon White ◽  
Tieshan Yang ◽  
Nikolai Dontschuk ◽  
Chi Li ◽  
Zaiquan Xu ◽  
...  
Keyword(s):  
Information Science ◽  
Hexagonal Boron Nitride ◽  
Van Der Waals ◽  
Quantum Systems ◽  
Electrostatic Model ◽  
Electrical Control ◽  
Van Der Waals Heterostructure ◽  
Stable Quantum ◽  
Significant Attention ◽  
Quantum Emitters

Abstract Controlling and manipulating individual quantum systems in solids underpins the growing interest in development of scalable quantum technologies1, 2. Recently, hexagonal boron nitride (hBN) has garnered significant attention in quantum photonic applications due to its ability to host optically stable quantum emitters3-7. However, the large band gap of hBN and the lack of efficient doping inhibits electrical triggering and limits opportunities to study electrical control of emitters. Here, we show an approach to electrically modulate quantum emitters in an hBN–graphene van der Waals heterostructure. We show that quantum emitters in hBN can be reversibly activated and modulated by applying a bias across the device. Notably, a significant number of quantum emitters are intrinsically dark, and become optically active at non-zero voltages. To explain the results, we provide a heuristic electrostatic model of this unique behaviour. Finally, employing these devices we demonstrate a nearly-coherent source with linewidths of ~ 160 MHz. Our results enhance the potential of hBN for tunable solid state quantum emitters for the growing field of quantum information science.

scholarly journals Unraveling energy and charge transfer in type-II van der Waals heterostructures

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Junyi Liu ◽  
Zi Li ◽  
Xu Zhang ◽  
Gang Lu
Keyword(s):  
Energy Transfer ◽  
Charge Transfer ◽  
First Principles ◽  
Rational Design ◽  
Van Der Waals ◽  
Band Alignment ◽  
Type Ii ◽  
First Principles Calculations ◽  
Comprehensive Picture ◽  
Excitonic Effect

AbstractRecent experiments observed significant energy transfer in type-II van der Waals (vdW) heterostructures, such as WS2/MoSe2, which is surprising due to their staggered band alignment and weak spectral overlap. In this work, we carry out first-principles calculations to shed light on energy and charge transfer in WS2/MoSe2 heterostructure. Incorporating excitonic effect in nonadiabatic electronic dynamics, our first-principles calculations uncover a two-step process in competing energy and charge transfer, unravel their relative efficiencies and explore the means to control their competition. While both Dexter and Förster mechanisms can be responsible for energy transfer, they are shown to operate at different conditions. The excitonic effect is revealed to drive ultrafast energy and charge transfer in type-II WS2/MoSe2 heterostructure. Our work provides a comprehensive picture of exciton dynamics in vdW heterostructures and paves the way for rational design of novel vdW heterostructures for optoelectronic and photovoltaic applications.

Atomistic insight into the significantly enhanced photovoltaic cells of monolayer GaTe2via two-dimensional van der Waals heterostructures engineering

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Francis Opoku ◽  
Penny P. Govender
Keyword(s):  
Solar Cells ◽  
Charge Transfer ◽  
Density Functional ◽  
Van Der Waals ◽  
Photovoltaic Cells ◽  
Density Functional Theory Method ◽  
Binding Energies ◽  
Band Alignment ◽  
Two Dimensional ◽  
Photovoltaic Solar Cells

AbstractDesigning new van der Waals (vdW) heterostructures from various two-dimensional transition metal dichalcogenides (TMDs) materials shows outstanding properties, such as an ultrafast charge transfer process and strong interlayer interactions by combining the advantageous properties of the different TMD materials. In this study, using the density functional theory method, we systemically investigate the optical property, band alignment, electronic structures, interface charge transfer, mechanical properties and stability of MTe2/GaTe2 (M = Mo and W) vdW heterostructures as promising photovoltaic solar cells materials. In this work, gallium telluride and MTe2 were used as acceptors and donors in high-quality photovoltaic cells. The calculated binding energies suggest that they were energetically favourable and relatively easy to fabricate under suitable conditions. Moreover, the heterostructures possess exceptional characteristics of enhanced visible light absorption edge (∼104 cm−1), type-II band alignment and strong charge separation. The suitable band alignment leads to maximum power conversion efficiency (PCE) of 22.43 and 22.91%, respectively, which was quite promising for photovoltaic solar cells. The high PCE could be due to the internal built-in electric field at the MTe2/GaTe2 interface, which induces efficient separation of charge carriers. This work offers theoretical support for the design and prediction of next-generation low-cost, highly efficient and promising materials for solar device applications.

A first-principles study on the electronic and optical properties of a type-II C2N/g-ZnO van der Waals heterostructure

2021 ◽  
Vol 23 (6) ◽  
pp. 3963-3973
Author(s):  
Jianxun Song ◽  
Hua Zheng ◽  
Minxia Liu ◽  
Geng Zhang ◽  
Dongxiong Ling ◽  
...  
Keyword(s):  
Optical Properties ◽  
Dft Calculations ◽  
First Principles ◽  
Van Der Waals ◽  
Band Alignment ◽  
Type Ii ◽  
Electronic And Optical Properties ◽  
Direct Bandgap ◽  
Van Der Waals Heterostructure ◽  
Vdw Heterostructure

The structural, electronic and optical properties of a new vdW heterostructure, C2N/g-ZnO, with an intrinsic type-II band alignment and a direct bandgap of 0.89 eV at the Γ point are extensively studied by DFT calculations.

scholarly journals Density Distribution Maps: A Novel Tool for Subcellular Distribution Analysis and Quantitative Biomedical Imaging

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 1009
Author(s):  
Ilaria De Santis ◽  
Michele Zanoni ◽  
Chiara Arienti ◽  
Alessandro Bevilacqua ◽  
Anna Tesei
Keyword(s):  
Density Distribution ◽  
Large Scale ◽  
Super Resolution ◽  
Spatial Location ◽  
Relative Displacement ◽  
Distribution Analysis ◽  
Laboratory Equipment ◽  
Imaging Device ◽  
Distribution Maps ◽  
Super Resolution Microscopy

Subcellular spatial location is an essential descriptor of molecules biological function. Presently, super-resolution microscopy techniques enable quantification of subcellular objects distribution in fluorescence images, but they rely on instrumentation, tools and expertise not constituting a default for most of laboratories. We propose a method that allows resolving subcellular structures location by reinforcing each single pixel position with the information from surroundings. Although designed for entry-level laboratory equipment with common resolution powers, our method is independent from imaging device resolution, and thus can benefit also super-resolution microscopy. The approach permits to generate density distribution maps (DDMs) informative of both objects’ absolute location and self-relative displacement, thus practically reducing location uncertainty and increasing the accuracy of signal mapping. This work proves the capability of the DDMs to: (a) improve the informativeness of spatial distributions; (b) empower subcellular molecules distributions analysis; (c) extend their applicability beyond mere spatial object mapping. Finally, the possibility of enhancing or even disclosing latent distributions can concretely speed-up routine, large-scale and follow-up experiments, besides representing a benefit for all spatial distribution studies, independently of the image acquisition resolution. DDMaker, a Software endowed with a user-friendly Graphical User Interface (GUI), is also provided to support users in DDMs creation.

Femtosecond nano-videography of interlayer charge transfer in van der Waals heterostructures

2021 ◽  
Author(s):  
M. Zizlsperger ◽  
M. Plankl ◽  
P. E. Faria Junior ◽  
F. Mooshammer ◽  
T. Siday ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Van Der Waals ◽  
Van Der Waals Heterostructures

Vertical strain and electric field tunable electronic properties of type-II band alignment C2N/InSe van der Waals heterostructure

2019 ◽  
Vol 716 ◽  
pp. 155-161 ◽  
Author(s):  
Khang D. Pham ◽  
Nguyen N. Hieu ◽  
Le M. Bui ◽  
Huynh V. Phuc ◽  
Bui D. Hoi ◽  
...  
Keyword(s):  
Electric Field ◽  
Electronic Properties ◽  
Van Der Waals ◽  
Band Alignment ◽  
Type Ii ◽  
Vertical Strain ◽  
Van Der Waals Heterostructure

From Divergence to Convergence in Hungarian Librarianship: Towards a Common Digital Platform

Libri ◽  
2018 ◽  
Vol 68 (4) ◽  
pp. 315-329
Author(s):  
Péter Kiszl ◽  
Rita Radó ◽  
Miklós Péter Hubay
Keyword(s):  
Information Systems ◽  
Large Scale ◽  
Information Science ◽  
Public Libraries ◽  
Public Library ◽  
Professional Activities ◽  
Community Organisation ◽  
Digital Development ◽  
Library Network ◽  
Development Plans

Abstract Hungarian librarianship and related research are sadly underrepresented in international literature. With this article we intend to fill this gap and inform the experts of library and information science of some of the most recent Hungarian innovations. After showcasing the international professional connections of Hungarian librarianship, we present the structure of the Hungarian public library network and its mode of operation. We also analyse current and future main digital development plans, projects and the most important related professional activities of Hungarian libraries. Emphasis is placed on information systems promoting cooperation between libraries and the issues of the National Library System Project, which is a large-scale modernisation programme carried out between 2016 and 2018, designed to develop the IT system of the National Széchényi Library. After introducing the information systems of academic and specialised libraries and the access models of scientific databases provided by multinational and Hungarian content services, we also discuss the endeavours of public libraries aiming for multifunctionality and community organisation. The paper ends by providing insights into how the outcomes of the recent initiatives have been fed back into Hungarian LIS training courses offered in higher education.

scholarly journals Investigation on the interlayer coupling and bonding in layered nitride-halides ThNF and ThNCl

RSC Advances ◽  
2021 ◽  
Vol 11 (46) ◽  
pp. 28698-28703
Author(s):  
Xiao Liu ◽  
Da-Yong Liu ◽  
Ting-Ting Li ◽  
Dong-Meng Chen ◽  
Liang-Jian Zou
Keyword(s):  
Charge Transfer ◽  
Chemical Bond ◽  
Van Der Waals ◽  
Interlayer Coupling ◽  
Li Ion

Showing that the interlayer charge transfer and chemical bond in ThNF and ThNCl are considerable larger than the van der Waals compound ZrNCl, addressing the difficulty in intercalating Li ion or other charged molecules.

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