- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Two-dimensional (PEA) <sub/>2</sub> PbBr <sub/>4</sub> perovskite single crystals for a high performance UV-detector
摘要： Two-dimensional (2D) metallic transition metal dichalcogenides (MTMDCs), the complement of 2D semiconducting TMDCs, have attracted extensive attentions in recent years because of their versatile properties such as superconductivity, charge density wave, and magnetism. To promote the investigations of their fantastic properties and broad applications, the preparation of large-area, high-quality, and thickness-tunable 2D MTMDCs has become a very urgent topic and great efforts have been made. This topical review therefore focuses on the introduction of the recent achievements for the controllable syntheses of 2D MTMDCs (VS2, VSe2, TaS2, TaSe2, NbS2, NbSe2, etc.). To begin with, some earlier developed routes such as chemical vapor transport, mechanical/chemical exfoliation, as well as molecular beam epitaxy methods are briefly introduced. Secondly, the scalable chemical vapor deposition methods involved with two sorts of metal-based feedstocks, including transition metal chlorides and transition metal oxidations mixed with alkali halides, are discussed separately. Finally, challenges for the syntheses of high-quality 2D MTMDCs are discussed and the future research directions in the related fields are proposed.
关键词： metallic transition metal dichalcogenides,synthesis,chemical vapor deposition,two dimensional
更新于2025-09-19 17:15:36
-
Fluorescence and Raman Enhancement Effect Caused by a Chemical Mechanism in Metal-Tetraphenylporphyrin on 2D Layered Materials
摘要： Two-dimensional (2D) layered materials exhibiting a flat surface have been strong candidates for studies investigating both the fundamental Raman enhancement in these materials and their practical applications. Here, we explore the Raman and the fluorescence enhancement effects of metal-tetraphenylporphyrin (TPP) molecules on graphene and MoSe2. We attribute the enhancement behaviors to the charge transfer interaction between the 2D materials and the adsorbates. The enhancement factors for the two flat substrates are dissimilar due to the charge transfer ability resulting from the electronic structures. The charge transfer interaction can be explained by the adsorption probability based on Langmuir's model.
关键词： Fluorescence enhancement,Raman enhancement,Two-dimensional materials
更新于2025-09-19 17:15:36
-
Thickness-controlled synthesis of CoX2 (X = S, Se, Te) single crystalline 2D layers with linear magnetoresistance and high conductivity.
摘要： Two-dimensional (2D) materials especially transition metal dichalcogenides (TMDs) have drawn intensive interests owing to their plentiful properties. Some TMDs with magnetic elements (Fe, Co, Ni, etc.) are reported to be magnetic theoretically and experimentally, which undoubtedly provide a promising platform to design functional devices and study physical mechanisms. Nevertheless, plenty of the theoretical TMDs remain unrealized experimentally. In addition, the governable synthesis of these kinds of TMDs with desired thickness and high crystallinity poses a tricky challenge. Here, we report a controlled preparation of CoX2 (X = S, Se, Te) nanosheets through chemical vapor deposition (CVD). The thickness, lateral scale and shape of the crystals show great dependence with temperature and the thickness can be controlled from monolayer to tens of nanometers. Magneto-transport characterization and Density Function Theory (DFT) simulation indicate CoSe2 and CoTe2 are metallic. Besides, unsaturated and linear magnetoresistance have been observed even up to 9 Tesla. The conductivity of CoSe2 and CoTe2 can reach 5 × 106 and 1.8 × 106 S/m respectively, which is pretty high and even comparable with silver. These cobalt-based TMDs show great potential to work as 2D conductors and also provide a promising platform for investigating their magnetic properties.
关键词： Transition metal dichalcogenides,Magnetoresistance,Conductivity,Two-dimensional materials,Chemical vapor deposition
更新于2025-09-19 17:13:59
-
Plasmonic Metasurfaces Situated on Ultra-thin Carbon Nanomembranes
摘要： During the last decade, optical metasurfaces consisting of designed nanoresonators arranged in a planar fashion were successfully demonstrated to allow for the realization of a large variety of flat optical components. However, in common implementations of metasurfaces and metasurface-based devices, their flat nature is thwarted by the presence of a substrate of macroscopic thickness, which is needed to mechanically support the individual nanoresonators. Here, we demonstrate that Carbon Nanomembranes (CNMs) having nanoscale thickness can be used as a basis for arranging array of plasmonic nano-resonators into a metamembrane, allowing for the realization of genuinely flat optical devices. CNMs belong to the family of two-dimensional materials, and their thickness, mechanical, chemical, and electrical properties can be tailored by the choice of the molecular precursors used for their fabrication. We experimentally fabricate gold split-ring-resonator (SRR) metasurfaces on top of a free-standing CNM, which has a thickness of only about 1 nm and shows negligible interaction with the incident light field. For optical characterization of the fabricated SRR CNM metasurfaces, we perform linear-optical transmittance spectroscopy, revealing the typical resonance structure of an SRR metasurface. Furthermore, numerical calculations assuming free-standing SRR arrays are in excellent agreement with corresponding experimental transmittance spectra. We believe that our scheme offers a versatile solution for the realization of ultrathin, ultra lightweight metadevices, and may initiate various future research directions and applications including complex sensor technologies, conformal coating of complex topographies with functional metasurfaces, fast prototyping of multilayer metasurfaces, and studying the optical properties of effectively free-standing nanoparticles without the need for levitation schemes.
关键词： carbon nanomembranes,two-dimensional materials,nanoplasmonics,flat-optics,metasurfaces
更新于2025-09-19 17:13:59
-
Waveguide-integrated van der Waals heterostructure photodetector at telecom wavelengths with high speed and high responsivity
摘要： Intensive efforts have been devoted to the exploration of new optoelectronic devices based on two-dimensional transition-metal dichalcogenides (TMDCs) owing to their strong light–matter interaction and distinctive material properties. In particular, photodetectors featuring both high-speed and high-responsivity performance are of great interest for a vast number of applications such as high-data-rate interconnects operated at standardized telecom wavelengths. Yet, the intrinsically small carrier mobilities of TMDCs become a bottleneck for high-speed application use. Here, we present high-performance vertical van der Waals heterostructure-based photodetectors integrated on a silicon photonics platform. Our vertical MoTe2–graphene heterostructure design minimizes the carrier transit path length in TMDCs and enables a record-high measured bandwidth of at least 24 GHz under a moderate bias voltage of –3 V. Applying a higher bias or employing thinner MoTe2 flakes boosts the bandwidth even to 50 GHz. Simultaneously, our device reaches a high external responsivity of 0.2 A W–1 for incident light at 1,300 nm, benefiting from the integrated waveguide design. Our studies shed light on performance trade-offs and present design guidelines for fast and efficient devices. The combination of two-dimensional heterostructures and integrated guided-wave nano photonics defines an attractive platform to realize high-performance optoelectronic devices, such as photodetectors, light-emitting devices and electro-optic modulators.
关键词： transition-metal dichalcogenides,photodetectors,silicon photonics,van der Waals heterostructures,two-dimensional materials
更新于2025-09-19 17:13:59
-
Doubly passively Q-switched Tm:YAP laser with MoS2 and WS2 saturable absorbers at 2 μm
摘要： By simultaneously inserting MoS2 and WS2 saturable absorbers (SAs) into laser resonator, a doubly passively Q-switched Tm:YAP laser at 2 μm was realized. Measurements of the average output power, the pulse width and the pulse repetition frequency (RF) have been undertaken. In comparison to singly Q-switched laser using MoS2 or WS2, the doubly Q-switched laser using both MoS2 and WS2 can generate more stable pulse trains with shorter pulse width and higher peak power. At the absorbed pump power of 6.04 W, the maximum peak power of 22.4 W and the shortest pulse width of 249.4 ns were obtained. While for singly Q-switched laser using MoS2 or WS2, they were 10.7 W, 528.4 ns and 14.4 W, 458.8 ns. The experimental results hit at a conclusion that the doubly passively Q-switched operation is an e?cient way to compress the pulse width, improve the peak power and enhance the stability of pulse trains at 2 μm waveband laser.
关键词： Pulse width,Peak power,Doubly passively Q-switch,Two-dimensional material
更新于2025-09-19 17:13:59
-
Accelerated Discovery of Two-Dimensional Optoelectronic Octahedral Oxyhalides via High-Throughput <i>Ab Initio</i> Calculations and Machine Learning
摘要： Traditional trial-and-error methods are obstacles for large-scale searching of new optoelectronic materials. Here, we introduce a method combining high-throughput ab initio calculations and machine-learning approaches to predict two-dimensional octahedral oxyhalides with improved optoelectronic properties. We develop an effective machine-learning model based on an expansive data set generated from density functional calculations including the geometric and electronic properties of 300 two-dimensional octahedral oxyhalides. Our model accelerates the screening of potential optoelectronic materials of 5000 two-dimensional octahedral oxyhalides. The distorted stacked octahedral factors proposed in our model play essential roles in the machine-learning prediction. Several potential two-dimensional optoelectronic octahedral oxyhalides with moderate band gaps, high electron mobilities, and ultrahigh absorbance coefficients are successfully hypothesized.
关键词： band gaps,optoelectronic materials,two-dimensional octahedral oxyhalides,absorbance coefficients,electron mobilities,high-throughput ab initio calculations,machine learning
更新于2025-09-19 17:13:59
-
Switchable and dual-wavelength ultrafast fibre lasers with an MoTe <sub/>2</sub> -based saturable absorber
摘要： Based on monolayer MoTe2 film, we have proposed a mode-locked fibre laser delivering single-wavelength and dual-wavelength solitons at the telecommunication band. The saturable absorber (SA) is synthesized by coating monolayer MoTe2 film on the pinhole of fibre pigtail. The experimental results show that our soliton lasers can work at the single- and dual-wavelength states, respectively, by appropriately adjusting the polarization controller. The proposed laser can work stably at the mode-locking state for several hours, indicating that monolayer MoTe2 film is an excellent SA material for ultrafast optics.
关键词： ultrafast fibre laser,two dimensional materials,Saturable absorber
更新于2025-09-19 17:13:59
-
Two-dimensional transition metal carbide and nitride (MXene) derived quantum dots (QDs): synthesis, properties, applications and prospects
摘要： The progress of two-dimensional (2D) MXene-derived QDs (MQDs) is in the early stages, but the materials have aroused great interest due to their high electrical conductivity, abundant active catalytic sites, easily tunable structure, satisfactory dispersibility, remarkable optical properties, good biocompatibility, manifold functionalizations, and so on. However, up to now, there is still no review paper on MQDs. Herein, the research advances of MQDs, including their synthetic routes (top-down and bottom-up methods), properties (structural, electronic, optical and magnetic properties), functionalizations (surface modifications, heteroatom doping and the construction of composites) and applications (sensing, biomedical, catalysis, energy storage and optoelectronic devices etc.), are critically highlighted, and the future prospects and challenges of MQDs are discussed. This review will serve as a one-stop point for comprehending the most advanced developments of MQDs, and will hopefully enlighten researchers to employ MQDs for satisfying the growing requirements of the diverse applications.
关键词： transition metal carbide,MXene,prospects,properties,nitride,Two-dimensional,applications,synthesis,quantum dots
更新于2025-09-19 17:13:59
-
Two-dimensional Ruddlesdena??Popper layered perovskite for light-emitting diodes
摘要： Solution-processed metal halide perovskite light-emitting diodes (PeLEDs) have attracted extensive attention due to the great potential application in energy-efficient lighting and displays. Two-dimensional Ruddlesden–Popper (2DRP) layered perovskites exhibit high photoluminescence quantum efficiency, improved film morphology, and enhanced operational stability over their three-dimensional counterparts, making them attractive for high-performance PeLEDs. In addition, 2DRP perovskite materials with a tunable exciton binding energy are suitable for preparing PeLEDs with color-tunability. In this perspective, we first introduce the merits of the 2DRP layered perovskites in terms of their structural characteristics. The progress in 2DRP PeLEDs is then reviewed. The challenges and new opportunities of the PeLEDs are finally discussed. We hope to open up new perspectives for rational designs of the 2DRP perovskite materials for PeLEDs with unprecedented efficiency and stability.
关键词： operational stability,film morphology,photoluminescence quantum efficiency,Two-dimensional Ruddlesden–Popper layered perovskite,color-tunability,light-emitting diodes
更新于2025-09-19 17:13:59