Regulating transient optical responses in twisted bilayer WS₂

Nanotechnology, Год журнала: 2025, Номер 36(18), С. 185202 - 185202

Опубликована: Март 28, 2025

Abstract The optical response manipulation of two-dimensional materials is crucial for designing and optimizing high-performance optoelectronic devices. Previously, modulation in semiconductors primarily relied on adjusting carrier density through excitation or charge injection using the energy band-filling effect. Recently, twist angle has been found to tune properties van der Waals structure, but its impact transient remains unexplored. Herein, we demonstrate that can effectively regulate behaviors by tracing evolution responses twisted bilayer WS 2 from 0° 60°. Both Raman PL spectra consistently show bilayers are highly dependent angle. Exciton behavior phonon modes exhibit similarity at angles near 60°, significantly change as approaches 30°. Moreover, was carefully investigated a femtosecond pump-probe technique. results reveal significant decrease thermalization/relaxation time exciton formation/recombination with ∼31.0°, compared ∼2.9° ∼58.9°, which be attributed accumulation intralayer carriers due weakened interlayer coupling. These modulate 2D materials. Our study elucidates dynamic provides new insights future photonic

Язык: Английский

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Intrinsic Electric Fields Promote Delocalized Interlayer Excitons in Janus In₂SSe Moiré Bilayers

The Journal of Physical Chemistry Letters, Год журнала: 2025, Номер unknown, С. 5272 - 5280

Опубликована: Май 19, 2025

The moiré potential in van der Waals (vdW) superlattices is well-established to significantly influence electronic structures and optical excitations. When Janus monolayers are employed construct twisted bilayers, an additional degree of freedom─the out-of-plane field─is introduced alongside the potential, leading modifications both properties. While these two effects have been individually investigated prior studies on excitons, behavior excitons under simultaneous presence remained unexplored. In this study, we investigate, for first time, interplay between In2SSe. Our results demonstrate that band excitonic properties can be modulated through variations stacking sequences intrinsic dipole orientations. This work provides a framework precise control emission energy, exciton characteristics, spatial distribution excitons. We predict coexistence field-induced interlayer potential-driven bilayer These findings not only elucidate interaction fields potentials but also introduce novel, multifaceted strategy manipulation.

Язык: Английский

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Lattice Distortion and Low-Frequency Anharmonic Phonons Suppress Charge Recombination in Lead Halide Perovskites upon Pseudohalide Doping: Time-Domain Ab Initio Analysis

The Journal of Physical Chemistry Letters, Год журнала: 2023, Номер 14(47), С. 10685 - 10692

Опубликована: Ноя. 21, 2023

Perovskite solar cells have witnessed a surge in interest as promising technology for low-cost, high-efficiency photovoltaics with certified power conversion efficiencies beyond 25%. However, their commercial development is hindered by poor stability and nonradiative losses that restrict approach to the theoretical efficiency limit. Using ab initio nonadiabatic molecular dynamics, we demonstrate charge recombination suppressed when iodide formamidinium lead (FAPbI3) partially replaced pseudohalide anions (SCN-, BF4-, PF6-). The replacement breaks symmetry of system creates local structural distortion dynamic disorder, decreasing electron-hole overlap electron-vibrational coupling. carrier lifetime found increase increased longest PF6-. This work fundamentally relevant design high-performance perovskite materials optoelectronic applications.

Язык: Английский

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Low-Frequency Raman Study of Large-Area Twisted Bilayers of WS₂ Stacked by an Etchant-Free Transfer Method

ACS Applied Materials & Interfaces, Год журнала: 2024, Номер 16(2), С. 2902 - 2911

Опубликована: Янв. 3, 2024

Monolayer transition metal dichalcogenides have strong intracovalent bonding. When stacked in multilayers, however, weak van der Waals interactions dominate interlayer mechanical coupling and, thus, influence their lattice vibrations. This study presents the frequency evolution of phonons twisted WS2 bilayers, highly subject to twist angle. The angle between layers is controlled modulate spacing layers, which, turn, affects that probed by Raman spectroscopy. shifts high-frequency E2g1 (Γ) and A1g phonon modes separations are dependent on angle, reflecting correlation In this work, we fabricated large-area, bilayer with a clean interface angles. Polarized spectroscopy identified new modes, which were not previously reported, depending appearance breathing spectra provides evidence structures. We confirm can alter exciton trion dynamics bilayers as indicated photoluminescence peak shift. These large-area samples practical applications optoelectronic device fabrication twistronics.

Язык: Английский

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Twisted BiOCl Moiré Superlattices for Photocatalytic Chloride Reforming of Methane

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(47), С. 32816 - 32825

Опубликована: Ноя. 12, 2024

Solar-driven conversion of CH4 into value-added methyl chlorides and H2 with abundant chloride ions offers a sustainable reforming strategy but suffers from inefficient Cl– activation severe e––h+ recombination in traditional photocatalysts. Herein, we demonstrate that BiOCl moiré superlattices 11.1° twist angle are highly efficient for photocatalytic CH3Cl NaCl. These superlattices, featuring misalignment-induced tensile strains, destabilize surface Bi–Cl bonds, facilitating hole-mediated MvK-analogous process to activate lattice Cl reactive •Cl chlorination. Meanwhile, their twisted stacking configurations reinforce interlayer electronic coupling thus accelerate out-of-plane carrier transfer. Along anchoring single-atom Pt sites evolution, the resulting Pt1/BiOCl deliver yield 53.4 μmol g–1 h–1 an impressive selectivity 96% under visible light. This study highlights potential engineering two-dimensional photocatalysts regulate structural strains dynamics decentralized CH4.

Язык: Английский

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