Single photon emission from localized excitons in two-dimensional (2D) materials has been extensively investigated because of its relevance for quantum information applications. Prerequisites are the availability of photons with high purity polarization and controllable polarization orientation that can be integrated with optical cavities. Here, deformation strain along edges of prepatterned square-shaped substrate protrusions is exploited to induce quasi-one-dimensional (1D) localized excitons in WSe monolayers as an elegant way to get photons that fulfill these requirements. At zero magnetic field, the emission is linearly polarized with 95% purity because exciton states are valley hybridized with equal shares of both valleys and predominant emission from excitons with a dipole moment along the elongated direction. In a strong field, one valley is favored and the linear polarization is converted to high-purity circular polarization. This deterministic control over polarization purity and orientation is a valuable asset in the context of integrated quantum photonics.
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http://dx.doi.org/10.1021/acs.nanolett.1c01927 | DOI Listing |
Nat Commun
December 2024
Department of Mechanical and Aerospace Engineering, University of California, Irvine, Irvine, CA, USA.
Tightly bound electron-hole pairs (excitons) hosted in atomically-thin semiconductors have emerged as prospective elements in optoelectronic devices for ultrafast and secured information transfer. The controlled exciton transport in such excitonic devices requires manipulating potential energy gradient of charge-neutral excitons, while electrical gating or nanoscale straining have shown limited efficiency of exciton transport at room temperature. Here, we report strain gradient induced exciton transport in monolayer tungsten diselenide (WSe) across microns at room temperature via steady-state pump-probe measurement.
View Article and Find Full Text PDFNanomaterials (Basel)
December 2024
Institute of Photonics and Nanotechnology, Faculty of Physics, Vilnius University, Saulėtekio Ave. 3, 10257 Vilnius, Lithuania.
We elaborate a method for determining the 0D-1D nanostructure size by photoluminescence (PL) emission spectrum dependence on the nanostructure dimensions. As observed, the high number of diamond-like carbon nanocones shows a strongly blue-shifted PL spectrum compared to the bulk material, allowing for the calculation of their top dimensions of 2.0 nm.
View Article and Find Full Text PDFJ Chem Theory Comput
December 2024
Department of Physics, School of Physical Science and Technology, Ningbo University, Ningbo 315211, P.R. China.
The evolution of photosynthetic reaction centers (RCs) from anoxygenic bacteria to higher-order oxygenic cynobacteria and plants highlights a remarkable journey of structural and functional diversification as an adaptation to environmental conditions. The role of chirality in these centers is important, influencing the arrangement and function of key molecules involved in photosynthesis. Investigating the role of chirality may provide a deeper understanding of photosynthesis and the evolutionary history of life on Earth.
View Article and Find Full Text PDFAdv Mater
December 2024
State Key Laboratory for Artificial Microstructure & Mesoscopic Physics and Frontiers Science Center for Nano-Optoelectronics, School of Physics, Peking University, Beijing, 100871, China.
Despite extensive studies on magnetic proximity effects, the fundamental excitonic properties of the 2D semiconductor-magnet heterostructures remain elusive. Here, the presence of localized excitons in MoSe/CrSBr heterostructures is unveiled, represented by a new photoluminescence emission feature, X. Our findings reveal that X originates from excitons confined by intrinsic defects in the CrSBr layer.
View Article and Find Full Text PDFNanophotonics
April 2024
Department of Physics and Electronics, Osaka Metropolitan University, Gakuen-cho, Naka-ku, Sakai-shi, Osaka 599-8531, Japan.
Light-emitting diodes (LEDs) are widely used as next-generation light sources because of their various advantages. However, their luminous efficiency is remarkably low at the green-emission wavelength. The luminous efficiencies of InGaN/GaN quantum wells (QWs) significantly decrease with increasing indium content in the green wavelength region, mainly owing to the quantum-confined Stark effect (QCSE).
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