MoSe2 and WSSe heterojunction with exceptional power conversion efficiency and photogalvanic effect

Materials Today Physics, Journal Year: 2023, Volume and Issue: 40, P. 101317 - 101317

Published: Dec. 15, 2023

Language: Английский

---

Breakdown of the Static Dielectric Screening Approximation of Coulomb Interactions in Atomically Thin Semiconductors

ACS Nano, Journal Year: 2025, Volume and Issue: 19(4), P. 4269 - 4278

Published: Jan. 21, 2025

Coulomb interactions in atomically thin materials are remarkably sensitive to variations the dielectric screening of environment, which can be used control exotic quantum many-body phases and engineer exciton potential landscapes. For decades, static or frequency-independent approximations response, where increased is predicted cause an energy redshift resonance, have been sufficient. These were first applied wells more recently extended with initial success layered transition metal dichalcogenides (TMDs). Here, we use charge-tunable resonances investigate effects TMD monolayers embedded low-frequency constants ranging from 4 than 1000, a range 2 orders magnitude larger previous studies. In contrast by models, observe blueshift resonance exceeding 30 meV higher constant environments. We explain our observations introducing dynamical model based on solution Bethe-Salpeter equation (BSE). When strong, find that binding remains mostly controlled while self-energy dominated high-frequency one. Our results supplant understanding their heterostructures, introduce knob tune selected effects, reshape framework for detecting controlling correlated states designing optoelectronic devices.

Language: Английский

---

Janus MoSSe Nanotubes on 1D SWCNT‐BNNT van der Waals Heterostructure

Small, Journal Year: 2025, Volume and Issue: unknown

Published: April 3, 2025

Two-dimensional (2D) Janus transition metal dichalcogenide (TMDC) layers with broken mirror symmetry exhibit giant Rashba splitting and unique excitonic behavior. For their one-dimensional (1D) counterparts, the nanotubes possess curvature, which introduces an additional degree of freedom to break structural symmetry. This can potentially enhance these effects or even give rise novel properties. Moreover, MSSe (M = W, Mo), diameters surpassing 40 Å Se positioned externally consistently demonstrate lower energy states compared monolayer counterparts. However, there are limited studies on preparation nanotubes, due synthesis challenge sample quality. In this study, we first synthesized MoS2 single-walled carbon nanotube (SWCNT) boron nitride (BNNT) heterostructures then explored growth MoSSe from at room temperature assistance H2 plasma. The successful formation structure is confirmed by Raman spectroscopy, atomic elemental distribution grown samples further characterized advanced electronic microscopy. based SWCNT-BNNT paves way for exploration properties in TMDC nanotubes.

Language: Английский

---

An Efficient Descriptor for Rapid Determination of Dipole Moments and Band Alignments of 2D Janus Transition‐Metal Dichalcogenides

Advanced Functional Materials, Journal Year: 2024, Volume and Issue: 34(33)

Published: March 4, 2024

Abstract The dipole moment ( µ ) is a critical parameter in Janus structures, influencing band alignments and carrier transmissions. However, evaluating 2D layers challenging due to the vast number of structures inefficiency Kelvin probe force microscopy. Using recently developed transition‐metal dichalcogenides (TMDCs) as prototype, descriptor proposed based on fundamental parameters (atomic atomic radii) investigate relationship between . By constructing 621 structural models, this applicable from monolayers three‐layers. considering shielding effect terminal atoms, performance has been significantly enhanced, resulting description accuracy 94.6% for all TMDC systems. Based descriptor, Anderson's Rule (AR) model can be extended bilayers simulating alignments, substantial improvement 20.0% 90.8%. This development holds crucial importance screening self‐doping P‐N junctions. work provides an efficient inherent properties rapid determining alignment TMDCs, accelerating design devices with built‐in electronic field structures.

Language: Английский

---

Nonlinear Optical Responses of Janus MoSSe/MoS₂ Heterobilayers Optimized by Stacking Order and Strain

ACS Nano, Journal Year: 2023, Volume and Issue: 17(20), P. 19877 - 19886

Published: Aug. 29, 2023

Nonlinear optical responses in second harmonic generation (SHG) of van der Waals heterobilayers, Janus MoSSe/MoS2, are theoretically optimized as a function strain and stacking order by adopting an exchange-correlation hybrid functional real-time approach first-principles calculation. We find that the calculated nonlinear susceptibility, χ(2), AA (550 pm/V) becomes three times large AB (170 due to broken inversion symmetry stacking. The present theoretical prediction is compared with observed SHG spectra MoSSe/MoS2 which peak intensity four Furthermore, relatively large, two-dimensional (4%) breaks C3v point group enhances χ(2) values for both (900 (300 stackings 1.6 without strain.

Language: Английский

---

Symmetry breaking in 2D materials for optimizing second-harmonic generation

Journal of Physics D Applied Physics, Journal Year: 2024, Volume and Issue: 57(33), P. 333002 - 333002

Published: May 13, 2024

Abstract Second-harmonic generation (SHG) is the of 2 ω (or half wavelength) light from incident with frequency as a nonlinear optical response material. Three-dimensional (3D) SHG materials are widely investigated for developing laser technology to obtain shorter wavelengths in photolithography fabrication semiconductor devices and medical sciences, such imaging techniques that do not use fluorescent materials. However, optimized intensity, 3D material required have no spatial-inversion symmetry non-centrosymmetry) special crystal structure so-called phase-matched condition). Recently, engineering breaking thin two-dimensional (2D) whose has inversion can offer breakthrough enhance intensity without requiring condition. Over past decade, many 2D been synthesized broken by stacking heterostructures, twisted moiré structures, dislocated nanoplates, spiral nanosheets, antiferromagnetic order, strain. In this review, we focus on recent progress rotational symmetries out-of-plane and/or in-plane directions. The theoretical calculations experimental setup briefly introduced non-linear We also present our perspectives how these optimize

Language: Английский

---

Out-of-plane Emission Dipole of Second Harmonic Generation in Odd- and Even-layered vdWs Janus Nb₃SeI₇

ACS Nano, Journal Year: 2024, Volume and Issue: 18(25), P. 16274 - 16284

Published: June 13, 2024

Integration of atomically thin nonlinear optical (NLO) devices demands an out-of-plane (OP) emission dipole second harmonic generation (SHG) to enhance the spontaneous for nanophotonics. However, research on van der Waals (vdWs) materials with OP SHG is still in its infancy. Here, by coupling back focal plane (BFP) imaging numerical simulations and density functional theory (DFT) calculations, we demonstrate that vdWs Janus Nb3SeI7, ranging from bulk monolayer limit, exhibits a dominant owing breaking symmetry. Explicitly, even-layered Nb3SeI7 C6v symmetry predicted exhibit pure attributed only second-order susceptibility coefficient χzxx. Meanwhile, although odd-layered C3v has both IP components (χzxx χyyy), value χzxx 1 order magnitude greater than χyyy, leading approximate SHG. Moreover, crystal can be preserved under hydrostatic pressure, accompanied enhanced resulting 3-fold increase intensity. The reported stable 2D facilitate rapid development chip-integrated NLO devices.

Language: Английский

---

Inversion Symmetry-Broken Tetralayer Graphene Probed by Second-Harmonic Generation

Nano Letters, Journal Year: 2024, Volume and Issue: 24(27), P. 8378 - 8385

Published: June 17, 2024

Stacking orders provide a unique way to tune the properties of two-dimensional materials. Recently, ABCB-stacked tetralayer graphene has been predicted possess atypical elemental ferroelectricity arising from its symmetry breaking but experimentally explored very little. Here, we observe pronounced nonlinear optical second-harmonic generation (SHG) in while absent both ABAB- and ABCA-stacked allotropes. Our results direct evidence graphene. The remarkable contrast SHG spectra allows straightforward identification ABCB domains other two kinds stacking order facilitates characterization their crystalline orientation. employed technique serves as convenient tool for exploring intriguing physics novel optics graphene, where spontaneous polarization intrinsically gapped flat bands coexist. establish platform studying rare noncentrosymmetric structures.

Language: Английский

---

Janus Doping of Sulfur into Platinum Diselenide Ribbons

Small Methods, Journal Year: 2024, Volume and Issue: unknown

Published: Aug. 23, 2024

Abstract 2D platinum diselenide (PtSe 2 ), a novel member of the transition metal dichalcogenides (TMDCs) family, possesses many excellent properties, including layer‐dependent bandgap, high carrier mobility, and broadband response, making it promise for applications in technologies like field‐effect transistors room‐temperature photodetectors. Doping represents an effective method to modify electrical properties TMDCs bestow upon them additional functions. However, date, little research has been conducted on successful doping PtSe modification. In this study, sulfur (S) powder is utilized during chemical vapor deposition growth process ribbons successfully integrated into lattice through substitutional doping. The Au substrate significantly decreases substitution energy Se atoms lower layer , resulting formation Janus PtSSe structure. S‐doped demonstrate significant symmetry breaking enhanced showcasing strong nonlinear optical response certain synaptic plasticity, further simulating some neuromorphological processes. This study not only demonstrates viable controllable modification but also establishes platform exploring characteristics TMDCs.

Language: Английский

---

Multi‐Scale Modeling of Surface Second‐Harmonic Generation in Centrosymmetric Molecular Crystalline Materials: How Thick is the Surface?

Advanced Optical Materials, Journal Year: 2024, Volume and Issue: 12(18)

Published: May 6, 2024

Abstract Second–harmonic generation (SHG) is forbidden in centrosymmetric materials. However, a signal observed from interfaces where the symmetry broken. Whereas effect can be phenomenologically accommodated, qualitative and quantitative description remained elusive, preventing exploration of questions such as how deep below surface second–harmonic generated. A multi–scale approach to compute total layer‐dependent intensity SHG molecular crystals thus presented. The microscopic origin identified models with embedding partial charges combined density functional theory (DFT) showing symmetry‐breaking distortions electron cloud layer approached. at level determined using time‐dependent DFT then brought macroscopic scale through rigorous self‐consistent multiple scattering formalism. two orders magnitude larger than next three layers below. This used for designing optimizing optical devices containing nonlinear materials, laminates. It shown that basic Kretschmann‐like setup enhance material thousand times.

Language: Английский

---