scholarly journals Realization of Lasing Emission from One Step Fabricated WSe2 Quantum Dots

Nanomaterials ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 538
Author(s):  
Pengpeng Ren ◽  
Wenfei Zhang ◽  
Yiqun Ni ◽  
Di Xiao ◽  
Honghao Wan ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Transition Metal Dichalcogenides ◽  
Laser Cavity ◽  
Threshold Value ◽  
Gain Medium ◽  
Excitation Wavelength ◽  
Excitation Threshold ◽  
Ultrasonic Probe ◽  
Metal Dichalcogenides ◽  
One Step

Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) quantum dots (QDs) are the vanguard due to their unique properties. In this work, WSe2 QDs were fabricated via one step ultrasonic probe sonication. Excitation wavelength dependent photoluminescence (PL) is observed from WSe2 QDs. Room-temperature lasing emission which benefits from 3.7 times enhancement of PL intensity by thermal treatment at ~470 nm was achieved with an excitation threshold value of ~3.5 kW/cm2 in a Fabry–Perot laser cavity. To the best of our knowledge, this is the first demonstration of lasing emission from TMDCs QDs. This indicates that TMDCs QDs are a superior candidate as a new type of laser gain medium.

scholarly journals VS2 as saturable absorber for Q-switched pulse generation

Nanophotonics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 2569-2576 ◽  
Author(s):  
Lu Li ◽  
Lihui Pang ◽  
Qiyi Zhao ◽  
Yao Wang ◽  
Wenjun Liu
Keyword(s):  
Saturable Absorber ◽  
Nonlinear Optical ◽  
Modulation Depth ◽  
Signal To Noise Ratio ◽  
Transition Metal Dichalcogenides ◽  
Laser Cavity ◽  
Pulse Generation ◽  
High Signal ◽  
Power Pulse ◽  
Metal Dichalcogenides

AbstractTransition metal dichalcogenides have been widely utilized as nonlinear optical materials for laser pulse generation applications. Herein, we study the nonlinear optical properties of a VS2-based optical device and its application as a new saturable absorber (SA) for high-power pulse generation. Few-layer VS2 nanosheets are deposited on the tapered region of a microfiber to form an SA device, which shows a modulation depth of 40.52%. After incorporating the microfiber-VS2 SA into an Er-doped fiber laser cavity, passively Q-switched pulse trains could be obtained with repetition rates varying from 95 to 233 kHz. Under the pump power of 890 mW, the largest output power and shortest pulse duration are measured to be 43 mW and 854 ns, respectively. The high signal-to-noise ratio of 60 dB confirms the excellent stability of the Q-switching state. To the best of our knolowdge, this is the first illustration of using VS2 as an SA. Our experimental results demonstrate that VS2 nanomaterials have a large potential for nonlinear optics applications.

scholarly journals The Photodetectors Based on Lateral Monolayer MoS2/WS2 Heterojunctions

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Caihong Li ◽  
Juntong Zhu ◽  
Wen Du ◽  
Yixuan Huang ◽  
Hao Xu ◽  
...  
Keyword(s):  
Communication Systems ◽  
Transition Metal Dichalcogenides ◽  
Chemical Vapor ◽  
Large Area ◽  
Optical Signals ◽  
Metal Dichalcogenides ◽  
One Step ◽  
The One ◽  
Charge Carrier Trapping ◽  
Sharp Interfaces

AbstractMonolayer transition metal dichalcogenides (TMDs) show promising potential for next-generation optoelectronics due to excellent light capturing and photodetection capabilities. Photodetectors, as important components of sensing, imaging and communication systems, are able to perceive and convert optical signals to electrical signals. Herein, the large-area and high-quality lateral monolayer MoS2/WS2 heterojunctions were synthesized via the one-step liquid-phase chemical vapor deposition approach. Systematic characterization measurements have verified good uniformity and sharp interfaces of the channel materials. As a result, the photodetectors enhanced by the photogating effect can deliver competitive performance, including responsivity of ~ 567.6 A/W and detectivity of ~ 7.17 × 1011 Jones. In addition, the 1/f noise obtained from the current power spectrum is not conductive to the development of photodetectors, which is considered as originating from charge carrier trapping/detrapping. Therefore, this work may contribute to efficient optoelectronic devices based on lateral monolayer TMD heterostructures.

Mechanisms of negative differential resistance in glutamine-functionalized WS2 quantum dots

2021 ◽  
Author(s):  
Denice Feria ◽  
Sonia Sharma ◽  
Yu-Ting Chen ◽  
Zhi-Ying Weng ◽  
Kuo-Pin Chiu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Negative Differential Resistance ◽  
Electronic Devices ◽  
Transition Metal Dichalcogenides ◽  
Differential Resistance ◽  
Voltage Range ◽  
Current Voltage ◽  
Metal Dichalcogenides ◽  
Current Voltage Characteristics ◽  
Memory Applications

Abstract Understanding the mechanism of the negative differential resistance (NDR) in transition metal dichalcogenides is essential for fundamental science and the development of electronic devices. Here, the NDR of the current-voltage characteristics was observed based on the glutamine-functionalized WS2 quantum dots (QDs). The NDR effect can be adjusted by varying the applied voltage range, air pressure, surrounding gases, and relative humidity. A peak-to-valley current ratio as high as 6.3 has been achieved at room temperature. Carrier trapping induced by water molecules was suggested to be responsible for the mechanism of the NDR in the glutamine-functionalized WS2 QDs. Investigating the NDR of WS2 QDs may promote the development of memory applications and emerging devices.

scholarly journals Spin-valley qubits in gated quantum dots in a single layer of transition metal dichalcogenides

2021 ◽  
Vol 104 (19) ◽  
Author(s):  
Abdulmenaf Altıntaş ◽  
Maciej Bieniek ◽  
Amintor Dusko ◽  
Marek Korkusiński ◽  
Jarosław Pawłowski ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Transition Metal ◽  
Transition Metal Dichalcogenides ◽  
Single Layer ◽  
Metal Dichalcogenides

scholarly journals Charge Transfer from Lead Sulfide Quantum Dots to MoS-=SUB=-2-=/SUB=- Nanoplatelets-=SUP=-*-=/SUP=-

2020 ◽  
Vol 128 (8) ◽  
pp. 1193
Author(s):  
I.D. Skurlov ◽  
A.S. Mudrak ◽  
A.V. Sokolova ◽  
S.A. Cherevkov ◽  
M.A. Baranov ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Charge Transfer ◽  
Transition Metal ◽  
Lead Sulfide ◽  
Transition Metal Dichalcogenides ◽  
Order Of Magnitude ◽  
Metal Dichalcogenides ◽  
High Carrier Mobility ◽  
High Carrier ◽  
Lead Sulfide Quantum Dots

The research interest in the transition metal dichalcogenides (TMD) has been reborn a few years ago. This had happened due to the remarkable properties of monolayered TMD (e. g. high carrier mobility and high exciton binding energy) and due to the development of the exfoliation methods. Photoconductive MoS2-based devices spectral range can be expanded to the NIR by coupling them with PbS QDs. However, this requires extensive knowledge about the the charge and energy transfer processes in such systems. In this paper, we investigate charge transfer between PbS QDs and MoS2 nanoplatelets (NPls). Using the PL decay analysis, we show how the charge transfer efficiency changes with the distance between the QDs and NPls, as well as with QD size. Last, we demonstrate that the addition of the MoS2 NPLs increases the photoconductive response for up to an order of magnitude, as compared to the bare QD. Keywords: transition metal dichalcogenides, quantum dots, charge transfer, lead sulfide, molybdenum disulfide.

scholarly journals Valley-selective energy transfer between quantum dots in atomically thin semiconductors

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Anvar S. Baimuratov ◽  
Alexander Högele
Keyword(s):  
Quantum Dots ◽  
Energy Transfer ◽  
Structural Control ◽  
Center Of Mass ◽  
Transition Metal Dichalcogenides ◽  
Binding Energies ◽  
Exciton Localization ◽  
Metal Dichalcogenides ◽  
Parabolic Confinement ◽  
Nonlocal Nature

Abstract In monolayers of transition metal dichalcogenides the nonlocal nature of the effective dielectric screening leads to large binding energies of excitons. Additional lateral confinement gives rise to exciton localization in quantum dots. By assuming parabolic confinement for both the electron and the hole, we derive model wave functions for the relative and the center-of-mass motions of electron–hole pairs, and investigate theoretically resonant energy transfer among excitons localized in two neighboring quantum dots. We quantify the probability of energy transfer for a direct-gap transition by assuming that the interaction between two quantum dots is described by a Coulomb potential, which allows us to include all relevant multipole terms of the interaction. We demonstrate the structural control of the valley-selective energy transfer between quantum dots.

scholarly journals Preparation of Few-Layered Wide Bandgap MoS2 with Nanometer Lateral Dimensions by Applying Laser Irradiation

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 164 ◽  
Author(s):  
Mitra Mahdavi ◽  
Salimeh Kimiagar ◽  
Fahimeh Abrinaei
Keyword(s):  
Laser Irradiation ◽  
Laser Energy ◽  
Transition Metal Dichalcogenides ◽  
Wide Bandgap ◽  
Mos2 Nanosheets ◽  
Uniform Size ◽  
Transmission Electron ◽  
Metal Dichalcogenides ◽  
One Step ◽  
Layered Mos2

In this study, we report a new method for the quick, green, and one-step preparation of few-layered molybdenum disulfide (MoS2) nanosheets with wide bandgap. MoS2 nanosheets with small lateral dimension and uniform size distribution were synthesized for various applications. MoS2 powder was synthesized using the hydrothermal method; then, thinned by applying laser irradiation with different energies from 40 to 80 mJ. Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis absorption spectra, and photoluminescence (PL) spectra were applied for the characterization of the MoS2 nanosheets in terms of morphology, crystal structures, and optical properties. The widest calculated bandgap 4.7 eV was for the sample under 80 mJ laser energy. The results confirmed the successful preparation of highly pure, uniform, and few-layered MoS2 nanosheets. Furthermore, it was possible to enhance the production rate of MoS2 nanosheets (including nanosheets and nanoparticles) through laser irradiation. Thus, the present paper introduces a simple and green alternative approach for preparing few-layered MoS2 nanosheets of transition metal dichalcogenides or other layered materials.

scholarly journals Tungsten-Modulated Molybdenum Selenide/Graphene Heterostructure as an Advanced Electrode for All-Solid-State Supercapacitors

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1477
Author(s):  
Qixian Liu ◽  
Jing Ning ◽  
Haibin Guo ◽  
Maoyang Xia ◽  
Boyu Wang ◽  
...  
Keyword(s):  
Solid State ◽  
Density Functional ◽  
Lattice Structure ◽  
Transition Metal Dichalcogenides ◽  
Potassium Ions ◽  
Functional Theory ◽  
Molybdenum Selenide ◽  
Isoelectronic Doping ◽  
Metal Dichalcogenides ◽  
One Step

Transition metal dichalcogenides (TMDs) have attracted widespread attention due to their excellent electrochemical and catalytic properties. In this work, a tungsten (W)-modulated molybdenum selenide (MoSe2)/graphene heterostructure was investigated for application in electrochemistry. MoSe2/graphene heterojunctions with low-doped W compositions were synthesized by a one-step hydrothermal catalysis approach. Based on the conducted density functional theory (DFT) calculations, it was determined that inserting a small amount of W (≈5%) into the MoSe2/graphene heterostructure resulted in the modification of its lattice structure. Additionally, an increase in the distance between layers (≈8%) and a decrease in the adsorption energy of the potassium ions (K+) (≈−1.08 eV) were observed following W doping. Overall, the electrochemical performance of the MoSe2/graphene hybrid was enhanced by the presence of W. An all-solid-state supercapacitor device prepared using electrodes based on the W-doped MoSe2/graphene composite achieved excellent capacitance of 444.4 mF cm−2 at 1 mV s−1. The results obtained herein revealed that the MoSe2/graphene hybrid exhibiting low W composition could be valuable in the field of energy storage and isoelectronic doping of TMDs.

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