scholarly journals Фотоиндуцированный перенос заряда в слоистых 2D наноструктурах PbSe-MoS-=SUB=-2-=/SUB=-

2022 ◽  
Vol 130 (2) ◽  
pp. 325
Author(s):  
И.Д. Скурлов ◽  
П.С. Парфёнов ◽  
А.В. Соколова ◽  
Д.А. Татаринов ◽  
А.А. Бабаев ◽  
...  
Keyword(s):  
Electrical Response ◽  
Transition Metal Dichalcogenides ◽  
Photoluminescence Intensity ◽  
Lead Chalcogenides ◽  
Ir Radiation ◽  
Near Ir ◽  
Ultrathin Layers ◽  
Photoluminescence Lifetime ◽  
Metal Dichalcogenides ◽  
Photoinduced Charge

Semiconductor 2D nanostructures are a new platform for the creation of modern optoelectronic devices. Layered 2D PbSe-MoS2 nanostructures with efficient photoinduced charge transfer from PbSe nanoplatelets (NPLs) to MoS2 were created. When PbSe NPLs with short organic ligands are deposited onto a thin layer of MoS2 NPLs, a decrease in their photoluminescence intensity and a decrease in the average photoluminescence lifetime are observed. When a layered 2D PbSe-MoS2 nanostructure is illuminated with IR radiation, a photocurrent appears, which indicates the contribution of PbSe NPLs to the electrical response of the system. Ultrathin layers of transition metal dichalcogenides sensitized with nanostructures based on lead chalcogenides can be used in photodetectors with a spectral sensitivity region extended to the near-IR range.

scholarly journals Photoinduced charge transfer in transition metal dichalcogenide heterojunctions – towards next generation energy technologies

2020 ◽  
Vol 13 (9) ◽  
pp. 2684-2740 ◽  
Author(s):  
Dana B. Sulas-Kern ◽  
Elisa M. Miller ◽  
Jeffrey L. Blackburn
Keyword(s):  
Charge Transfer ◽  
Transition Metal ◽  
Transition Metal Dichalcogenides ◽  
Transition Metal Dichalcogenide ◽  
Photoinduced Charge Transfer ◽  
Energy Applications ◽  
Energy Technologies ◽  
Broad Array ◽  
Metal Dichalcogenides ◽  
Photoinduced Charge

We review recent strides in understanding and manipulating photoinduced charge transfer in heterojunctions between 2D transition metal dichalcogenides and other semiconductors, with implications for a broad array of energy applications.

scholarly journals Efficient phonon cascades in WSe2 monolayers

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ioannis Paradisanos ◽  
Gang Wang ◽  
Evgeny M. Alexeev ◽  
Alisson R. Cadore ◽  
Xavier Marie ◽  
...  
Keyword(s):  
Excitation Energy ◽  
Laser Excitation ◽  
Transition Metal Dichalcogenides ◽  
Exciton State ◽  
Strong Temperature Dependence ◽  
Cascade Process ◽  
Photoluminescence Intensity ◽  
Tungsten Diselenide ◽  
Carrier Relaxation ◽  
Metal Dichalcogenides

AbstractEnergy relaxation of photo-excited charge carriers is of significant fundamental interest and crucial for the performance of monolayer transition metal dichalcogenides in optoelectronics. The primary stages of carrier relaxation affect a plethora of subsequent physical mechanisms. Here we measure light scattering and emission in tungsten diselenide monolayers close to the laser excitation energy (down to ~0.6 meV). We reveal a series of periodic maxima in the hot photoluminescence intensity, stemming from energy states higher than the A-exciton state. We find a period ~15 meV for 7 peaks below (Stokes) and 5 peaks above (anti-Stokes) the laser excitation energy, with a strong temperature dependence. These are assigned to phonon cascades, whereby carriers undergo phonon-induced transitions between real states above the free-carrier gap with a probability of radiative recombination at each step. We infer that intermediate states in the conduction band at the Λ-valley of the Brillouin zone participate in the cascade process of tungsten diselenide monolayers. This provides a fundamental understanding of the first stages of carrier–phonon interaction, useful for optoelectronic applications of layered semiconductors.

scholarly journals Spin/valley pumping of resident electrons in WSe2 and WS2 monolayers

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Cedric Robert ◽  
Sangjun Park ◽  
Fabian Cadiz ◽  
Laurent Lombez ◽  
Lei Ren ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Optical Pumping ◽  
Continuous Wave ◽  
Opposite Sign ◽  
Transition Metal Dichalcogenides ◽  
Optical Excitation ◽  
Photoluminescence Intensity ◽  
Dynamic Polarization ◽  
Continuous Wave Laser ◽  
Metal Dichalcogenides

AbstractMonolayers of transition metal dichalcogenides are ideal materials to control both spin and valley degrees of freedom either electrically or optically. Nevertheless, optical excitation mostly generates excitons species with inherently short lifetime and spin/valley relaxation time. Here we demonstrate a very efficient spin/valley optical pumping of resident electrons in n-doped WSe2 and WS2 monolayers. We observe that, using a continuous wave laser and appropriate doping and excitation densities, negative trion doublet lines exhibit circular polarization of opposite sign and the photoluminescence intensity of the triplet trion is more than four times larger with circular excitation than with linear excitation. We interpret our results as a consequence of a large dynamic polarization of resident electrons using circular light.

scholarly journals Unveiling defect-mediated carrier dynamics in monolayer semiconductors by spatiotemporal microwave imaging

2020 ◽  
Vol 117 (25) ◽  
pp. 13908-13913
Author(s):  
Zhaodong Chu ◽  
Chun-Yuan Wang ◽  
Jiamin Quan ◽  
Chenhui Zhang ◽  
Chao Lei ◽  
...  
Keyword(s):  
Carrier Transport ◽  
Electrical Response ◽  
Transition Metal Dichalcogenides ◽  
Chemical Vapor ◽  
Strongly Correlated ◽  
Trap States ◽  
Time Resolved ◽  
Metal Dichalcogenides ◽  
Microwave Signals ◽  
The Time Domain

The optoelectronic properties of atomically thin transition-metal dichalcogenides are strongly correlated with the presence of defects in the materials, which are not necessarily detrimental for certain applications. For instance, defects can lead to an enhanced photoconduction, a complicated process involving charge generation and recombination in the time domain and carrier transport in the spatial domain. Here, we report the simultaneous spatial and temporal photoconductivity imaging in two types of WS2monolayers by laser-illuminated microwave impedance microscopy. The diffusion length and carrier lifetime were directly extracted from the spatial profile and temporal relaxation of microwave signals, respectively. Time-resolved experiments indicate that the critical process for photoexcited carriers is the escape of holes from trap states, which prolongs the apparent lifetime of mobile electrons in the conduction band. As a result, counterintuitively, the long-lived photoconductivity signal is higher in chemical-vapor deposited (CVD) samples than exfoliated monolayers due to the presence of traps that inhibits recombination. Our work reveals the intrinsic time and length scales of electrical response to photoexcitation in van der Waals materials, which is essential for their applications in optoelectronic devices.

scholarly journals Super-resolved Optical Mapping of Reactive Sulfur-Vacancies in Two-Dimensional Transition Metal Dichalcogenides

ACS Nano ◽  
2021 ◽  
Author(s):  
Miao Zhang ◽  
Martina Lihter ◽  
Tzu-Heng Chen ◽  
Michal Macha ◽  
Archith Rayabharam ◽  
...  
Keyword(s):  
Transition Metal ◽  
Optical Mapping ◽  
Transition Metal Dichalcogenides ◽  
Two Dimensional ◽  
Metal Dichalcogenides
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