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Noble-metal-free MoS2 nanosheet-coupled MAPbI3 photocatalyst for efficient and stable visible-light-driven hydrogen evolution
摘要： We report that MoS2 nanosheets (MoS2 NSs) as an cocatalyst in situ coupled with MAPbI3 leads to a highly efficient composite photocatalyst for visible-light-driven photocatalytic H2 evolution. The most efficient MAPbI3/MoS2 NSs exhibits a high H2 evolution rate (206.1 μmol h-1) in MAPbI3-saturated HI solution, which is 121 times higher than that of pristine MAPbI3 (1.7 μmol h-1) and greatly superior to that of MAPbI3/Pt/C (68.5 μmol h-1), and the composite is very stable for H2 evolution in 156 h reaction.
关键词： photocatalyst,MoS2 nanosheets,visible-light-driven,MAPbI3,hydrogen evolution
更新于2025-09-19 17:13:59
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Direct growth of high-content 1T phase MoS2 film by pulsed laser deposition for hydrogen evolution reaction
摘要： The modified MoS2-based material, with a higher conductivity and rich active sites, is promising one of a variety of nonprecious-metal electrocatalysts for hydrogen evolution reaction (HER). Here, the bulk MoS2 is exfoliated to form small-size MoS2 clusters by pulse laser, which are diluted in solid sulfur and further to form porous film. The 1T phase MoS2 ratio in the prepared film was modulated by adding the different content of sulfur into MoS2 target. Besides, this addition also has an effect on the pore structure of films. Finally, the obtained high-content 1T phase MoS2 film provides the highly metallic conductivity and more active sites, which results in the more enhanced HER catalytic activity with a lower Tafel slope of 38 mV dec-1, a smaller overpotential of 151 mV at 10 mA cm-2, compared with the pure MoS2 film.
关键词： pulsed laser deposition,sulfur addition,1T phase MoS2,Hydrogen evolution reaction
更新于2025-09-19 17:13:59
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Photo-response in 2D metal chalcogenide-ferroelectric oxide heterostructure controlled by spontaneous polarization
摘要： The interplay between free and bound charges in two-dimensional (2D) semiconductor/ferroelectric oxide structures is responsible for the unique opto-electrical properties of these structures. In this study, we vertically combined the 2D layered semiconductors MoS2 (n-type) and WSe2 (p-type) with a ferroelectric oxide (PbTiO3) and found that a ferroelectric polarization induced accumulation or depletion in the layered materials. The heterostructures exhibited polarization-dependent charge distribution and pinched hysteresis. We show that polarization at the interface promoted e?cient charge separation of photo-generated carriers in the 2D layers. Optical control of electrical transport was e?ectively achieved in the MoS2 layers. This study potentially opens up new applications for semiconductor/ferroelectric systems in electronic devices.
关键词： opto-electrical properties,optical control,MoS2,2D semiconductor,ferroelectric oxide,PbTiO3,charge separation,WSe2
更新于2025-09-19 17:13:59
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Transition from Hopping to Band-like Transport in Weakly-coupled Multilayer MoS2 Field Effect Transistors
摘要： In this article, multilayer MoS2 manufactured from multiple-transfer process of chemical vapor deposition (CVD) grown monolayer MoS2 is studied. Due to the lattice mismatch and larger distance between adjacent MoS2 layers, the interlayer-interaction is weakened and the band structure transition from direct to indirect as well as band-gap shrinkage effect in multilayer is suppressed, as indicated by Raman and photoluminescence (PL) spectra. These structural differences from that of the exfoliated MoS2 make stacked MoS2 layers a better configuration for fabricating high-performance MoS2 FET. Here, back-gate MoS2 field effect transistors (FETs) with different number of layers were fabricated. As the number of layers increases from 1 to 3, the devices’ mobility and on/off ratio show an enhancement from 2 to 62cm2/s·V and 106 to 108, respectively. Metal to insulator transition (MIT) phenomena is also observed in bilayer MoS2 FET. A distributed resistance based model is proposed to study the conductivity of weak-coupled MoS2 layers. Combining the resistance model with temperature dependence characteristics, it is demonstrated that the electron mobility in monolayer MoS2 is limited by hopping transport mechanism, whereas the electron in bilayer can be excited to band-like transport mode due to the immunity of the influence from the charge traps at substrate, which explain the enhancement of mobility and MIT phenomena. This study is universally valid for other two dimensional (2D) materials, paving a way to fabricate high performance nano-electronics for integrated circuits.
关键词： CVD,MoS2,multilayer,metal-to-insulator transition,FET
更新于2025-09-19 17:13:59
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Comparative Study of High Order Harmonic Generation in Monolayer-Thick Semiconductors
摘要： In this contribution we report on the results of an experimental comparative study of high order harmonic generation (HHG) from strong mid-IR femtosecond laser pulses in two-dimensional (2D) materials consisting of a single layer. Beside their promising application in electronics and photonics, these materials allow to study microscopic light-condensed-matter interaction on the atomic scale. HHG in 2D materials, in comparison to a bulk, have several distinct qualitative features: single atom layer essentially excludes propagation effects and minimizes absorption, whereas weak charge screening results in significantly higher exciton binding energy. Here we report on comparative study of intensity and polarization dependence of HHG in polycrystalline single layers of MoS2 and WS2.
关键词： WS2,MoS2,mid-IR femtosecond laser pulses,2D materials,high order harmonic generation
更新于2025-09-16 10:30:52
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Preparation of Hybrid Molybdenum Disulfide/Single Wall Carbon Nanotube–n-Type Silicon Solar Cells
摘要： Carbon nanotube/silicon (CNT/Si) heterojunction solar cells represent one new architecture for photovoltaic devices. The addition of MoS2 to the devices is shown to increase the e?ciency of the devices. Two structures are explored. In one case, the single wall carbon nanotubes (SWCNTs) and MoS2 ?akes are mixed to make a hybrid, which is then used to make a ?lm, while in the other case, a two layer system is used with the MoS2 deposited ?rst followed by the SWCNTs. In all cases, the solar cell e?ciency is improved largely due to signi?cant increases in the ?ll factor. The rise in ?ll factor is due to the semiconducting nature of the MoS2, which helps with the separation of charge carriers.
关键词： molybdenum disul?de (MoS2),single wall carbon nanotubes (SWCNTs),thin ?lm,solar cells
更新于2025-09-16 10:30:52
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Self-assembled Ag(111) nanostructures induced by Fermi surface nesting
摘要： Scanning tunneling microscopy measurements on Ag(111)/MoS2 reveal atomically ?at preferred, or “magic,” heights occurring at 6, 10, and 14 atomic layers. These results are consistent with Ag growth on a variety of semiconducting substrates and correlate with electronic energy savings in electronic structure calculations of freestanding Ag(111) ?lms. Thus, under certain conditions, Ag will spontaneously form quantized structures independent of the substrate. To explain this, we have found Fermi surface nesting vectors in the bulk Ag band structure which account for these results and the fact Ag that is gapped along the surface normal. This model extends to a range of metallic systems which exhibit electronic con?nement, epitaxial growth, and minimal strain. As with Au/MoS2, the Ag/MoS2 system exhibits this behavior at unusually high temperatures so that these principles might be used for control over device features at the nanometer scale under standard fabrication conditions.
关键词： quantum size effects,MoS2,Fermi surface nesting,Ag(111),scanning tunneling microscopy
更新于2025-09-16 10:30:52
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Ambient atmosphere laser-induced local ripening of MoS <sub/>2</sub> nanoparticles
摘要： Transition metal dichalcogenide (TMDC) ultrathin layers have attracted considerable interest in the recent years. Their peculiar functional properties can be exploited in electronics, spintronics, optoelectronics, photonics, energy production, harvesting and storage. The availability of cost-effective, green, and efficient growth processes is of paramount importance and significant effort has been made in the research on various production methodologies. Here we report on a simple laser-based process which allows the direct writing of thin TMDC layers. In detail, by direct exposure to laser irradiation of a dip-coated MoS2 precursor, we obtained a three-dimensional arrangement of MoS2 nanoparticles in the form of platelets with a lateral dimension of about 50 nm and thickness down to bilayers. The characterization was assessed by AFM and Raman spectroscopy. The platelets are formed only in the central region of the laser spot, confirming that the material out of the spot is indeed an unprocessed precursor. By tuning the precursor deposition, we demonstrate the fabrication of MoS2 patterns with designed layer numbers. The proposed approach is highly versatile and can be applied also for the controlled growth of other TMDCs, as proved by the successful generation of WS2 layers.
关键词： Transition metal dichalcogenide,MoS2,direct writing,laser-induced,Raman spectroscopy,AFM
更新于2025-09-16 10:30:52
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Numerical analysis of the effect of MoS2 interface layers on copper-zinc-tin-sulfur thin film solar cells
摘要： MoS2 interface layers are often present in high-temperature sulfurized Cu2ZnSnS4 (CZTS) solar cells, but their effects remain poorly characterized. In this study, the effect of MoS2 on CZTS solar cells was analyzed in simulation. Meanwhile, the quantum confinement effects of MoS2, that is, the varied band gap of MoS2 with the thickness of MoS2 have been considered. When the thickness of MoS2 was varied, the performances of CZTS solar cells were improved by the p-type and n-type MoS2 with suitable thickness due to the reduction of band gap, decreasing height of barrier of p-CZTS/MoS2. The barrier was always observed at the MoS2/Mo interface. When the holes recombination velocity of MoS2/Mo interface was changed, the photovoltaic properties of CZTS solar cells were improved by the suitable recombination velocity of MoS2/Mo interface. The simulated results about the effect of MoS2 thickness were consistent with the reported experiment results.
关键词： MoS2,Cu2ZnSnS4 solar cell,Photovoltaic performance,Simulation
更新于2025-09-16 10:30:52
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Hexagonal Boron Nitride for Surface Passivation of Two-dimensional van der Waals Heterojunction Solar Cells
摘要： Two-dimensional (2D) semiconductors can be promising active materials for solar cells due to their advantageous electrical and optical properties, in addition to their ability to form high-quality van der Waals (vdW) heterojunctions using a simple process. Furthermore, the atomically thin nature of these 2D materials allows them to achieve light-weighted and transparent thin-film solar cells. However, strategies appropriate for optimizing their properties have not been extensively studied yet. In this paper, we propose a method for reducing the electrical loss of 2D vdW solar cells by introducing hexagonal boron nitride (h-BN) as a surface passivation layer. This method allowed us to enhance the photovoltaic performance of a MoS2/WSe2 solar cell. In particular, we observed ~74 % improvement of the power conversion efficiency owing to a large increase in both short-circuit current and open-circuit voltage. Such a remarkable performance enhancement was due to the reduction of the recombination rate at the junction and surface of non-overlapped semiconductor regions, which was confirmed via time-resolved photoluminescence analysis. Furthermore, the h-BN top layer was found to improve the long-term stability of the tested 2D solar cell under ambient conditions. We observed the evolution of our MoS2/WSe2 solar cell for a month and found that h-BN passivation effectively suppressed its degradation speed. In particular, the degradation speed of the passivated cell was twice as low as that of a non-passivated cell. This work reveals that h-BN can successfully suppress the electrical loss and degradation of 2D vdW heterojunction solar cells under ambient conditions.
关键词： surface passivation,solar cell,MoS2,WSe2,2D material,van der Waals heterojunction,h-BN
更新于2025-09-16 10:30:52