Controlling exciton distribution in WS2 monolayer on a photonic crystal

2022 ◽  
Author(s):  
Xiu Zhang ◽  
Zhenshi Chen ◽  
Dong Liu ◽  
Lei Wan ◽  
Xuekai Ma ◽  
...  
Keyword(s):  
Photonic Crystal ◽  
Room Temperature ◽  
Transition Metal Dichalcogenides ◽  
Atomic Scale ◽  
Polarization Distribution ◽  
Scale Thickness ◽  
Optical Modes ◽  
Metal Dichalcogenides ◽  
Ws2 Monolayer ◽  
Exciton Distribution

Abstract Transition metal dichalcogenides (TMDCs) monolayers are promising candidates for novel optoelectronic devices, because they exhibit unique combination of atomic-scale thickness, direct bandgap and ease of integration proporties. In this work, we manipulate the exciton propagation in WS2 monolayer integatd with a photonic crystal at room temperature. By coupling with the optical modes of the photonic crystal, the excitons can propagate along a particular direction by around∼10μm. Moreimportantly, the excitons propagate along the particular direction with locked linear polarization up to 60%. Our results pave the way to manipulate the polarization distribution and propagation of the excitons in the WS2 monolayer.

scholarly journals Site-Specific Electrodeposition Enables Self-Terminating Growth of Atomically Dispersed Metal Catalysts

2020 ◽  
Author(s):  
Yi Shi ◽  
Wenmao Huang ◽  
Jian Li ◽  
Yue Zhou ◽  
Zhongqiu Li ◽  
...  
Keyword(s):  
Large Scale ◽  
Transition Metal Dichalcogenides ◽  
Metal Catalysts ◽  
Atomic Scale ◽  
Single Atom ◽  
Scale Production ◽  
Heterogenous Catalysis ◽  
Site Specific ◽  
Metal Support ◽  
Metal Dichalcogenides

<p>The growth of atomically dispersed metal catalysts (ADMCs) remains a great challenge owing to the thermodynamically driven atom aggregation. Here we report a surface-limited electrodeposition technique that uses site-specific substrates for the rapid and room-temperature synthesis of ADMCs. We obtained ADMCs by the underpotential deposition (UPD) of a single-atom nonnoble metal onto the chalcogen atoms of chemically exfoliated transition metal dichalcogenides and subsequent galvanic displacement with a more-noble single-atom metal. The site-specific electrodeposition (SSED) enables the formation of energetically favorable metal–support bonds, and then automatically terminates the sequential formation of metallic bonding. The self-terminating effect restricts the metal deposition to the atomic scale. The modulated ADMCs exhibit remarkable activity and stability in the hydrogen evolution reaction compared to state-of-the-art single-atom electrocatalysts. We demonstrate that this SSED methodology could be extended to the synthesis of a variety of ADMCs (for example, Pt, Pd, Rh, Cu, Pb, Bi, and Sn single atoms), showing its general scope for the large-scale production of functional ADMCs in heterogenous catalysis. </p>

scholarly journals Site-Specific Electrodeposition Enables Self-Terminating Growth of Atomically Dispersed Metal Catalysts

2020 ◽  
Author(s):  
Yi Shi ◽  
Wenmao Huang ◽  
Jian Li ◽  
Yue Zhou ◽  
Zhongqiu Li ◽  
...  
Keyword(s):  
Large Scale ◽  
Transition Metal Dichalcogenides ◽  
Metal Catalysts ◽  
Atomic Scale ◽  
Single Atom ◽  
Scale Production ◽  
Heterogenous Catalysis ◽  
Site Specific ◽  
Metal Support ◽  
Metal Dichalcogenides

<p>The growth of atomically dispersed metal catalysts (ADMCs) remains a great challenge owing to the thermodynamically driven atom aggregation. Here we report a surface-limited electrodeposition technique that uses site-specific substrates for the rapid and room-temperature synthesis of ADMCs. We obtained ADMCs by the underpotential deposition (UPD) of a single-atom nonnoble metal onto the chalcogen atoms of chemically exfoliated transition metal dichalcogenides and subsequent galvanic displacement with a more-noble single-atom metal. The site-specific electrodeposition (SSED) enables the formation of energetically favorable metal–support bonds, and then automatically terminates the sequential formation of metallic bonding. The self-terminating effect restricts the metal deposition to the atomic scale. The modulated ADMCs exhibit remarkable activity and stability in the hydrogen evolution reaction compared to state-of-the-art single-atom electrocatalysts. We demonstrate that this SSED methodology could be extended to the synthesis of a variety of ADMCs (for example, Pt, Pd, Rh, Cu, Pb, Bi, and Sn single atoms), showing its general scope for the large-scale production of functional ADMCs in heterogenous catalysis. </p>

Atomic-Scale Chemical Conversion of Single-Layer Transition Metal Dichalcogenides

ACS Nano ◽  
2019 ◽  
Vol 13 (5) ◽  
pp. 5611-5615
Author(s):  
Peng Chen ◽  
Yun-Ting Chen ◽  
Ro-Ya Liu ◽  
Han-De Chen ◽  
Dengsung Lin ◽  
...  
Keyword(s):  
Transition Metal ◽  
Transition Metal Dichalcogenides ◽  
Single Layer ◽  
Chemical Conversion ◽  
Atomic Scale ◽  
Layer Transition ◽  
Metal Dichalcogenides

scholarly journals Intrinsic lifetime of higher excitonic states in tungsten diselenide monolayers

Nanoscale ◽  
2019 ◽  
Vol 11 (25) ◽  
pp. 12381-12387 ◽  
Author(s):  
Samuel Brem ◽  
Jonas Zipfel ◽  
Malte Selig ◽  
Archana Raja ◽  
Lutz Waldecker ◽  
...  
Keyword(s):  
Transition Metal ◽  
Room Temperature ◽  
Transition Metal Dichalcogenides ◽  
Optical Spectra ◽  
Tungsten Diselenide ◽  
Dielectric Screening ◽  
Metal Dichalcogenides ◽  
Excitonic States

The reduced dielectric screening in atomically thin transition metal dichalcogenides allows to study the hydrogen-like series of higher exciton states in optical spectra even at room temperature.

scholarly journals Probing magnetism in atomically thin semiconducting PtSe2

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Ahmet Avsar ◽  
Cheol-Yeon Cheon ◽  
Michele Pizzochero ◽  
Mukesh Tripathi ◽  
Alberto Ciarrocchi ◽  
...  
Keyword(s):  
Long Range ◽  
Magnetic Moments ◽  
Transition Metal Dichalcogenides ◽  
Magnetic Ordering ◽  
Atomic Scale ◽  
First Principles Calculations ◽  
Microscopy Imaging ◽  
Transmission Electron ◽  
Metal Dichalcogenides ◽  
The One

Abstract Atomic-scale disorder in two-dimensional transition metal dichalcogenides is often accompanied by local magnetic moments, which can conceivably induce long-range magnetic ordering into intrinsically non-magnetic materials. Here, we demonstrate the signature of long-range magnetic orderings in defective mono- and bi-layer semiconducting PtSe2 by performing magnetoresistance measurements under both lateral and vertical measurement configurations. As the material is thinned down from bi- to mono-layer thickness, we observe a ferromagnetic-to-antiferromagnetic crossover, a behavior which is opposite to the one observed in the prototypical 2D magnet CrI3. Our first-principles calculations, supported by aberration-corrected transmission electron microscopy imaging of point defects, associate this transition to the interplay between the defect-induced magnetism and the interlayer interactions in PtSe2. Furthermore, we show that graphene can be effectively used to probe the magnetization of adjacent semiconducting PtSe2. Our findings in an ultimately scaled monolayer system lay the foundation for atom-by-atom engineering of magnetism in otherwise non-magnetic 2D materials.

scholarly journals Site-specific electrodeposition enables self-terminating growth of atomically dispersed metal catalysts

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Yi Shi ◽  
Wen-Mao Huang ◽  
Jian Li ◽  
Yue Zhou ◽  
Zhong-Qiu Li ◽  
...  
Keyword(s):  
Transition Metal Dichalcogenides ◽  
Metal Catalysts ◽  
Atomic Scale ◽  
Single Atom ◽  
Site Specific ◽  
Metal Support ◽  
Metal Dichalcogenides ◽  
Metallic Bonding ◽  
General Scope ◽  
Sequential Formation

Abstract The growth of atomically dispersed metal catalysts (ADMCs) remains a great challenge owing to the thermodynamically driven atom aggregation. Here we report a surface-limited electrodeposition technique that uses site-specific substrates for the rapid and room-temperature synthesis of ADMCs. We obtained ADMCs by the underpotential deposition of a non-noble single-atom metal onto the chalcogen atoms of transition metal dichalcogenides and subsequent galvanic displacement with a more-noble single-atom metal. The site-specific electrodeposition enables the formation of energetically favorable metal–support bonds, and then automatically terminates the sequential formation of metallic bonding. The self-terminating effect restricts the metal deposition to the atomic scale. The modulated ADMCs exhibit remarkable activity and stability in the hydrogen evolution reaction compared to state-of-the-art single-atom electrocatalysts. We demonstrate that this methodology could be extended to the synthesis of a variety of ADMCs (Pt, Pd, Rh, Cu, Pb, Bi, and Sn), showing its general scope for functional ADMCs manufacturing in heterogeneous catalysis.

scholarly journals Exciton–phonon coupling strength in single-layer MoSe2 at room temperature

2020 ◽  
Author(s):  
Donghai Li ◽  
Chiara Trovatello ◽  
Stefano Dal Conte ◽  
Matthias Nuß ◽  
Giancarlo Soavi ◽  
...  
Keyword(s):  
Room Temperature ◽  
Research Effort ◽  
Transition Metal Dichalcogenides ◽  
Optoelectronic Devices ◽  
Single Layer ◽  
Semiconductor Nanostructures ◽  
Phonon Coupling ◽  
Layer Transition ◽  
Fundamental Physics ◽  
Metal Dichalcogenides

Abstract Single-layer transition metal dichalcogenides (1L-TMDs) are at the center of an ever increasing research effort both in terms of fundamental physics and applications. Exciton–phonon coupling (EXPC) plays a key role in determining the photonic and (opto)electronic properties of 1L-TMDs. However, the EXPC strength has not been measured at room temperature. Here, we develop two-dimensional (2D) micro-spectroscopy to determine EXPC of 1L-MoSe2. We detect beating signals as a function of waiting time T, induced by the coupling between the A exciton and the A'1 optical phonon. Analysis of 2D beating maps provides the EXPC with the help of simulations. The Huang–Rhys factor of ~1 is larger than in most other inorganic semiconductor nanostructures. Our technique offers a unique tool to measure EXPC also in other 1L-TMDs and heterogeneous semiconducting systems with a spatial resolution ~260 nm, and will provide design-relevant parameters for the development of novel optoelectronic devices.

scholarly journals Enhancing monolayer photoluminescence on optical micro/nanofibers for low-threshold lasing

2019 ◽  
Vol 5 (11) ◽  
pp. eaax7398 ◽  
Author(s):  
Feng Liao ◽  
Jiaxin Yu ◽  
Zhaoqi Gu ◽  
Zongyin Yang ◽  
Tawfique Hasan ◽  
...  
Keyword(s):  
Room Temperature ◽  
Dynamic Range ◽  
Transition Metal Dichalcogenides ◽  
Pump Intensity ◽  
Environmental Stability ◽  
Quantum Yields ◽  
Light Emitters ◽  
Practical Applications ◽  
Metal Dichalcogenides ◽  
High Pump

Although monolayer transition metal dichalcogenides (TMDs) have direct bandgaps, the low room-temperature photoluminescence quantum yields (QYs), especially under high pump intensity, limit their practical applications. Here, we use a simple photoactivation method to enhance the room-temperature QYs of monolayer MoS2 grown on to silica micro/nanofibers by more than two orders of magnitude in a wide pump dynamic range. The high-density oxygen dangling bonds released from the tapered micro/nanofiber surface are the key to this strong enhancement of QYs. As the pump intensity increases from 10−1 to 104 W cm−2, our photoactivated monolayer MoS2 exhibits QYs from ~30 to 1% while maintaining high environmental stability, allowing direct lasing with greatly reduced thresholds down to 5 W cm−2. Our strategy can be extended to other TMDs and offers a solution to the most challenging problem toward the realization of efficient and stable light emitters at room temperature based on these atomically thin materials.

scholarly journals Design of photonic microcavities in hexagonal boron nitride

2018 ◽  
Vol 9 ◽  
pp. 102-108 ◽  
Author(s):  
Sejeong Kim ◽  
Milos Toth ◽  
Igor Aharonovich
Keyword(s):  
Photonic Crystal ◽  
Boron Nitride ◽  
Room Temperature ◽  
Emission Rate ◽  
Hexagonal Boron Nitride ◽  
Two Dimensional ◽  
Spontaneous Emission Rate ◽  
Photonic Crystal Cavities ◽  
Optical Modes ◽  
Optimal Coupling

We propose and design photonic crystal cavities (PCCs) in hexagonal boron nitride (hBN) for diverse photonic and quantum applications. Two dimensional (2D) hBN flakes contain quantum emitters which are ultra-bright and photostable at room temperature. To achieve optimal coupling of these emitters to optical resonators, fabrication of cavities from hBN is therefore required to maximize the overlap between cavity optical modes and the emitters. Here, we design 2D and 1D PCCs using anisotropic indices of hBN. The influence of underlying substrates and material absorption are investigated, and spontaneous emission rate enhancements are calculated. Our results are promising for future quantum photonic experiments with hBN.

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