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Laser-Beam-Patterned Topological Insulating States on Thin Semiconducting
摘要： Identifying the two-dimensional (2D) topological insulating (TI) state in new materials and its control are crucial aspects towards the development of voltage-controlled spintronic devices with low-power dissipation. Members of the 2D transition metal dichalcogenides have been recently predicted and experimentally reported as a new class of 2D TI materials, but in most cases edge conduction seems fragile and limited to the monolayer phase fabricated on specified substrates. Here, we realize the controlled patterning of the 1T0 phase embedded into the 2H phase of thin semiconducting molybdenum-disulfide by laser beam irradiation. Integer fractions of the quantum of resistance, the dependence on laser-irradiation conditions, magnetic field, and temperature, as well as the bulk gap observation by scanning tunneling spectroscopy and theoretical calculations indicate the presence of the quantum spin Hall phase in our patterned 1T0 phases.
关键词： MoS2,quantum spin Hall effect,laser-beam-patterned,2D materials,topological insulating states
更新于2025-09-16 10:30:52
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Enhancing Quantum Yield in Strained MoS2 Bilayers by Morphology-controlled Plasmonic Nanostructures towards Superior Photodetectors
摘要： Recently, extracting hot electrons from plasmonic nanostructures and utilizing them to enhance the optical quantum yield of 2D transition-metal dichalcogenides (TMDs) have been topics of interest in the field of optoelectronic device applications, such as solar cells, light emitting diodes, photodetectors and so on. The coupling of plasmonic nanostructures with nanolayers of TMDs depends on the optical properties of the plasmonic materials, including radiation pattern, resonance strength, and hot electron injection efficiency. Herein, we demonstrate the augmented photodetection of a large-scale, transfer-free bilayer MoS2, by decorating this TMD with four different morphology-controlled plasmonic nanoparticles. This approach allows engineering the bandgap of the bilayer MoS2 due to localized strain that stems up from plasmonic nanoparticles. In particular, the plasmonic strain blue shifts the band gap of bilayer MoS2 with 32 times enhanced photoresponse demonstrating immense hot electron injection. Besides, we observed the varied photoresponse of MoS2 bilayer hybridized with different morphology controlled plasmonic nanostructures. Although, hot electron injection was a substantial factor for photocurrent enhancement in hybrid plasmonic-semiconductor devices, our investigations further show that other key factors such as highly directional plasmonic modes, high aspect-ratio plasmonic nanostructures and plasmonic strain induced beneficial band-structure modifications were crucial parameters for effective coupling of plasmons with excitons. As a result, our study sheds light on designing highly tailorable plasmonic nanoparticles integrated transition metal dichalcogenide-based optoelectronic devices.
关键词： Plasmonic Nanostructures,Strained MoS2 Bilayers,Quantum Yield,Photodetectors
更新于2025-09-16 10:30:52
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Facile Preparation of Molybdenum Disulfide Quantum Dots Using a Femtosecond Laser
摘要： Molybdenum disulfide (MoS2) is rapidly emerging in a wide range of applications owing to its superior optical, electrical, and catalytic properties. In particular, aside from the current great interest in monolayer MoS2, MoS2 quantum dots (QDs) have received much attention in the electronics and optoelectronics fields owing to their inherent electrical and optical properties arising from the quantum confinement effect. Thus, various methods for producing MoS2 QDs, such as exfoliation, substrate growth, and colloidal synthesis, have been attempted. In this study, the method for manufacturing MoS2 QD with a size of 10 nm which is simpler than the conventional method was devised. On the basis of characterization of the prepared MoS2 QD samples, resistive switching devices was fabricated. These devices demonstrated stable unipolar resistive switching behavior without an electroforming process. This study provides a new approach for the mass production of MoS2 QD and one of their potential applications.
关键词： exfoliation,memristor,MoS2,quantum confinement effect,phase transition
更新于2025-09-16 10:30:52
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Rapid, facile, reagentless, and room-temperature conjugation of monolayer MoS2 nanosheets with dual-fluorophore-labled flares as Nanoprobes for ratiometric sensing of TK1 mRNA in living cells
摘要： Direct loading of fluorophore-labeled DNA molecules (named as flares) on gold nanoparticles (AuNPs) is a controllable and straightforward approach for intracellular imaging of target DNA molecules. However, the modification of AuNPs with flares requires a tedious and time-consuming procedure, additional reagents, or adenosine-rich DNA molecules. Here, we developed a rapid, simple, reagentless, and room-temperature approach for the modification of monolayer molybdenum disulfide nanosheets (M-MoS2 NSs) with dual-fluorophore-labeled flares, which were implemented for ratiometric imaging of TK1 mRNA in living cells. The duplexes were prepared by hybridizing thiolated single-stranded DNA (ssDNA) to 6-carboxyfluorescein (FAM)- and 5-carboxytetramethylrhodamine (TAMRA)-labeled flares. Fabrication of the nanoflares was conducted by conjugating the formed duplexes to the surface sulfur vacancy sites of the M-MoS2 NSs. The time for preparing the nanoflares was found to be completed within 1 h. In the nanoflares, FAM stays away from TAMRA, leading to inefficient fluorescence resonance energy transfer (FRET). The presence of perfectly matched DNA (DNApm) molecules induces the liberation of the flares from the nanoflares. The liberated flares fold into hairpin-shaped structures, causing high FRET efficiency from FAM to TAMRA and efficient FAM-TAMRA static quenching. Following this mechanism, the nanoflares provided an effective platform for ratiometric sensing of DNApm molecules with the limit of detection (at a signal-to-noise ratio of 3) of 8 nM and the linear range of 25?500 nM. Confocal microscopy experiments demonstrated that the nanoflares can be used to ratiometrically image TK1 mRNA in HeLa and MCF-7 cells.
关键词： ratiometric sensing,monolayer MoS2 nanosheets,TK1 mRNA,dual-fluorophore-labeled flares,living cells
更新于2025-09-16 10:30:52
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GaSe/MoS <sub/>2</sub> Heterostructure with Ohmica??Contact Electrodes for Fast, Broadband Photoresponse, and Selfa??Driven Photodetectors
摘要： In this letter, the vertically-stacked GaSe/MoS2 heterostructures with indium tin oxide (ITO) and Ni/Au as contact electrodes are successfully fabricated, respectively. The GaSe/MoS2 heterostructure exhibits a broadband photoresponse covering the range of visible to near-infrared spectra at room temperature without external bias voltage. When ITO serves as contact electrodes, a high rectification ratio, i.e., 1.5 × 104 at VDS = ±1 V, and an excellent photoelectric performance, i.e., responsivity of ≈0.67 A W-1, specific detectivity of ≈2.3 × 1011 cm Hz1/2 W-1 and external quantum efficiency of ≈160% at the wavelength of 520 nm is achieved. Moreover, the GaSe/MoS2 heterostructure with Ohmic-contact ITO electrodes demonstrates a faster response time of 155 μs, which is 4 times faster than the GaSe/MoS2 heterostructure with Ni/Au electrodes and about 300 times faster than previous reports. These results reveal the presence of an abrupt p–n junction between GaSe and MoS2 and significant role of electrode-contact mode in determining the photoelectric properties of GaSe/MoS2 heterostructure.
关键词： photoresponse,GaSe/MoS2 heterostructure,self-driven photodetector,Ohmic-contact
更新于2025-09-16 10:30:52
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Core-shell hollow spheres of type C@MoS2 for use in surface-assisted laser desorption/ionization time of flight mass spectrometry of small molecules
摘要： Mesoporous carbon hollow spheres coated with MoS2 (C@MoS2) were synthesized to obtain a material with large specific surface area, fast electron transfer efficiency and good water dispersibility. The composite material was applied as a matrix for the analysis of small molecules by surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF MS). The use of a core-shell C@MoS2 matrix strongly reduces matrix background interferences and increases signal intensity in the analysis of sulfonamides antibiotics (SAs), cationic dyes, emodin, as well as estrogen and amino acids. The composite material was applied to the SALDI-TOF MS analysis of selected molecules in (spiked) real samples. The ionization mechanism of the core-shell C@MoS2 as a matrix is discussed. The method exhibits low fragmentation interference, excellent ionization efficiency, high reproducibility and satisfactory salt tolerance.
关键词： Ionization mechanism,Core-shell C@MoS2,Emodin,Estrogen,Amino acids,Cationic dyes,Sulfonamides antibiotics,SALDI-TOF MS,Salt tolerance
更新于2025-09-12 10:27:22
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Solution Processed MoS<sub>2</sub> Quantum Dots/GaAs Vertical Heterostructures based Self-powered Photodetectors with Superior Detectivity
摘要： The characteristics of a novel 0D/3D heterojunction photodetector fabricated using solution processed colloidal MoS2 quantum dots (QDs) on GaAs is being presented. MoS2 QDs with a dimension of ~2 nm, synthesized by standard sono-chemical exfoliation process of 2D layers have been used for the purpose. The microscopic and spectroscopic studies confirmed the formation of semiconducting (2H phase) MoS2 QDs. The photodetectors were fabricated using n-GaAs substrates with two different doping concentrations resulting in n-n heterojunctions between n-type 0D MoS2 QDs and bulk n-GaAs. The devices fabricated using GaAs having higher doping concentration, upon illumination, showed an increase of reverse current of the order of ~102, while the same with lower doping concentration showed an increase of the order of ~103. All the heterojunction photodetector devices show a broadband operation over the visible wavelength range of 400 – 950 nm, with a peak responsivity of the devices being observed at 500 nm. The peak responsivity and detectivity are found to be ~400 mA/W and ~4 × 1012 Jones, respectively even without any external applied bias, which are useful for self-powered photodetection. Results indicate that colloidal MoS2/GaAs based hybrid heterostructures provide a platform for fabricating broadband photodetectors by using highly absorbing MoS2 QDs, which may show the pathway towards next-generation optoelectronic devices with superior detection properties.
关键词： MoS2,detectivity,quantum dots,photodetectors,vertical heterostructure,GaAs
更新于2025-09-12 10:27:22
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Photo-Carrier-Guiding Behavior of Vertically Grown MoS2 and MoSe2 in Highly Efficient Low-Light Transparent Photovoltaic Devices on Large-Area Rough Substrates
摘要： Two-dimensional MoX2 (X = S, Se) films were vertically grown on highly rough transparent conducting F-doped SnO2 glass substrates for the first time and successfully used as photogenerated carrier-guiding layers (CGLs) in transparent hydrogenated amorphous silicon (a-Si:H) thin film solar cells (TFSCs). The MoSe2 CGL layers could be grown at 530 °C using thermally cracked small Se-molecules on transparent FTO glass substrates and significantly improved cell performance. A transparent cell transmitting 26.0% of visible light with a 20-nm-thick vertically grown MoSe2 CGL showed an outstanding power conversion efficiency of 27.1% at a light intensity of 0.16 mW cm?2 (500 lux; corresponding to normal indoor irradiation). The shunt resistance (Rsh) of the TFSCs reached 32,000 Ω at a light intensity of 7 mW cm?2. An Rsh value this large is essential for low-light photovoltaic (PV) devices to prevent the dissipation of photogenerated carriers. These results strongly demonstrate that transparent a-Si:H-TFSCs with vertically grown MoX2 films should find wide use in building-integrated PV windows or indoor PV applications, as they can generate power even in very low-light environments.
关键词： orientation-controlled deposition,MoS2,low light intensity,transparent solar cells,MoSe2
更新于2025-09-12 10:27:22
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Direct Z-scheme photocatalytic removal of ammonia via the narrow band gap MoS2/N-doped graphene hybrid catalyst upon near-infrared irradiation
摘要： Near-infrared (NIR) irradiation accounts for approximately 54.3% of the solar spectrum. Therefore, MoS2 and N-doped graphene (NG) were utilised to fabricate a direct Z-scheme NIR-response photocatalytic system (MoS2/NG). The photocatalytic tests showed that MoS2/NG Z-scheme photocatalytic system can result in a 99.6% degradation ratio of ammonia under NIR irradiation, whereas the removal ratio of ammonia was only 64.0% using MoS2 as the photocatalyst under similar conditions. The catalytic e?ciency is still over 90.7% even if the MoS2/NG catalyst was used for ?ve runs, indicating that it is extremely stable. The kinetic research indicated the ?1. The average apparent rate constant kapp for ammonia degradation into N2 was at approximately 0.251 h enhanced photocatalytic activity of MoS2/NG was attributed to the more positive valence band level of the Z-scheme system.
关键词： MoS2/N-doped graphene,Near-infrared irradiation,Degradation ammonia,Narrow band gap,Z-scheme photocatalysis
更新于2025-09-12 10:27:22
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[IEEE 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - Berlin, Germany (2019.6.23-2019.6.27)] 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - Highly Sensitive and Reliable Strain Sensor Based on MoS <sub/>2</sub> -Decorated Laser-Scribed Graphene for Wearable Electronics
摘要： We propose a strategy for the fabrication of a highly sensitive and reliable strain sensor based on MoS2-decorated laser-scribed graphene (MDS-LSG) for flexible and wearable electronics. The laser-thinning of multilayered MoS2 coated on commercial polyimide (PI) film using a CO2 infrared laser exhibits three-dimensional hierarchical porous graphene network decorated with MoS2 enabling superior electrical properties. By exploiting the advantage of high mobility of graphene and strain-dependent property of MoS2, the technique offers a rapid route towards a simple, facile and scalable approach for the fabrication of high-performance strain sensor. As fabricated sensor endows high sensitivity (gauge factor, GF ~290), wide working range, fast response time and stability over 7000 cycles. Finally, we successfully apply the sensor’s performance for subtle deformation of the skin (wrist pulse) and various human-motion detections.
关键词： subtle strain,laser scribing,MoS2-decorated laser-scribed graphene (MDS-LSG),strain sensor
更新于2025-09-12 10:27:22