scholarly journals Carrier multiplication in van der Waals layered transition metal dichalcogenides

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Ji-Hee Kim ◽  
Matthew R. Bergren ◽  
Jin Cheol Park ◽  
Subash Adhikari ◽  
Michael Lorke ◽  
...  
Keyword(s):  
Heat Dissipation ◽  
Van Der Waals ◽  
Transition Metal Dichalcogenides ◽  
High Energy ◽  
Ultrafast Optical ◽  
Photovoltaic Energy Conversion ◽  
Carrier Multiplication ◽  
Ultrafast Optical Spectroscopy ◽  
Metal Dichalcogenides ◽  
Layered Transition Metal

AbstractCarrier multiplication (CM) is a process in which high-energy free carriers relax by generation of additional electron-hole pairs rather than by heat dissipation. CM is promising disruptive improvements in photovoltaic energy conversion and light detection technologies. Current state-of-the-art nanomaterials including quantum dots and carbon nanotubes have demonstrated CM, but are not satisfactory owing to high-energy-loss and inherent difficulties with carrier extraction. Here, we report CM in van der Waals (vdW) MoTe2 and WSe2 films, and find characteristics, commencing close to the energy conservation limit and reaching up to 99% CM conversion efficiency with the standard model. This is demonstrated by ultrafast optical spectroscopy with independent approaches, photo-induced absorption, photo-induced bleach, and carrier population dynamics. Combined with a high lateral conductivity and an optimal bandgap below 1 eV, these superior CM characteristics identify vdW materials as an attractive candidate material for highly efficient and mechanically flexible solar cells in the future.

Heteroepitaxy Between Lattice Mismatched Materials with Van Der Waals Interactions

1990 ◽  
Vol 198 ◽  
Author(s):  
Atsushi Koma
Keyword(s):  
Van Der Waals ◽  
Transition Metal Dichalcogenides ◽  
Three Dimensional ◽  
Matching Condition ◽  
Van Der Waals Interactions ◽  
Heteroepitaxial Growth ◽  
Lattice Matching ◽  
Metal Dichalcogenides ◽  
Layered Transition Metal ◽  
Growth Methods

ABSTRACTThe lattice matching condition encountered usually in the heteroepitaxial growth has been proved to be relaxed drastically, if one uses the interface having van der Waals nature. Such interface can be realized on a cleaved face of a layered material or a quasi-one dimensional material and on a surface of a dangling-bond-terminated three dimensional material. Various kinds of heterostructures, which cannot be made by conventional growth methods, can be fabricated by using a variety of layered transition metal dichalcogenides, in which there exist superconducting, metallic, semiconducting or insulating layered materials. Moreover those heterostructures have been found to be grown on such an ordinary three-dimensional material as GaAs, if the dangling bonds on its surface are terminated by suitable atoms.

scholarly journals High-energy collective electronic excitations in layered transition-metal dichalcogenides

2014 ◽  
Vol 90 (12) ◽  
Author(s):  
Pierluigi Cudazzo ◽  
Kari O. Ruotsalainen ◽  
Christoph J. Sahle ◽  
Ali Al-Zein ◽  
Helmuth Berger ◽  
...  
Keyword(s):  
Transition Metal ◽  
Transition Metal Dichalcogenides ◽  
High Energy ◽  
Electronic Excitations ◽  
Metal Dichalcogenides ◽  
Layered Transition Metal

scholarly journals Structural and High-Pressure Properties of Rheniite (ReS2) and (Re,Mo)S2

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 207
Author(s):  
Jordi Ibáñez-Insa ◽  
Tomasz Woźniak ◽  
Robert Oliva ◽  
Catalin Popescu ◽  
Sergi Hernández ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Density Functional ◽  
Van Der Waals ◽  
Transition Metal Dichalcogenides ◽  
Compression Behavior ◽  
Novel Device ◽  
Metal Dichalcogenides ◽  
Layered Transition Metal ◽  
Mo Content

Rhenium disulfide (ReS2), known in nature as the mineral rheniite, is a very interesting compound owing to its remarkable fundamental properties and great potential to develop novel device applications. Here we perform density functional theory (DFT) calculations to investigate the structural properties and compression behavior of this compound and also of the (Re,Mo)S2 solid solution as a function of Re/Mo content. Our theoretical analysis is complemented with high-pressure X-ray diffraction (XRD) measurements, which have allowed us to reevaluate the phase transition pressure and equation of state of 1T-ReS2. We have observed the 1T-to-1T’ phase transition at pressures as low as ~2 GPa, and we have obtained an experimental bulk modulus, B0, equal to 46(2) GPa. This value is in good agreement with PBE+D3 calculations, thus confirming the ability of this functional to model the compression behavior of layered transition metal dichalcogenides, provided that van der Waals corrections are taken into account. Our experimental data and analysis confirm the important role played by van der Waals effects in the high-pressure properties of 1T-ReS2.

Phonon Coupling and Dielectric Response in 2D Semiconductor

NANO ◽  
2021 ◽  
Author(s):  
Arslan Usman ◽  
Abdul Sattar ◽  
Hamid Latif ◽  
Muhammad Imran
Keyword(s):  
Transition Metal Dichalcogenides ◽  
Coupling Mechanism ◽  
Two Dimensional ◽  
Electron Hole ◽  
Exciton Coupling ◽  
Gain Energy ◽  
Metal Dichalcogenides ◽  
Layered Transition Metal ◽  
The Impact

The impact of phonon and their surrounding environment on exciton and its complexes were investigated in monolayer WSe2 semiconductor. Phonon up-conversion has been studied in past for conventional III–V semiconductors, but its role in two-dimensional layered transition metal dichalcogenides has rarely been explored. We investigated the photoluminescence up-conversion mechanism in WSe2 monolayer and found that a lower energy photon gain energy upto 64[Formula: see text]meV to be up-converted to emission photon at room temperature. Moreover, the phonon-exciton coupling mechanism has also been investigated and the role of dielectric screening has been explored to get complete insight of coulomb’s interaction in these electron-hole pairs. Investigations of charge carrier’s lifetime reveal that boron nitride encapsulated monolayer has shorter recombination time as low as 41 ps as compared to a bare monolayer on SiO2 substrate. These results are very promising for realizing spintronics-based application from two-dimensional layered semiconductors.

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