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Two-dimensional beta-lead oxide quantum dots
摘要： In recent years, black-phosphorus-analogue (BPA) two-dimensional (2D) materials have been explored to demonstrate promising optoelectronic performances and distinguished ambient stabilities, holding great promise in practical applications. Here, one new kind of BPA material, orthorhombic β-PbO quantum dots (QDs), is successfully fabricated by a facile liquid phase exfoliation (LPE) technique. The as-prepared β-PbO QDs show a homogeneous distribution of the lateral size (3.2 ± 0.9 nm) and thickness (2.5 ± 0.5 nm), corresponding to 4 ± 1 layers. The carrier dynamics of β-PbO QDs was systematically investigated via a femtosecond resolution transient absorption approach in the visible wavelength regime and it was clarified that two decay components were resolved with a decay time of τ1 = 2.3 ± 0.3 ps and τ2 = 87.9 ± 6.0 ps, respectively, providing important insights into their potential applications in the field of ultrafast optics, nanomechanics and optoelectronics. As a proof-of-concept, β-PbO QDs were, for the first time to our knowledge, fabricated as a working electrode in a photoelectrochemical (PEC)-typed photodetector that exhibits significantly high photocurrent density and excellent stability under ambient conditions.
关键词： photoelectrochemical photodetector,β-PbO quantum dots,carrier dynamics,liquid phase exfoliation
更新于2025-11-19 16:56:42
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Linear and Nonlinear Optical Properties of Few-Layer Exfoliated SnSe Nanosheets
摘要： Monochalcogenides of group IV elements have been considered as phosphorene analogs due to their similar crystal and electronic structure. Here, few-layer SnSe nanosheets are synthesized by a sonication-assisted liquid phase exfoliation process and their linear and nonlinear optical properties are examined. The as-exfoliated few-layer (FL) SnSe demonstrates layer thickness from 2 to 10 nm and lateral size of 150 nm with high crystallinity. Optical measurement confirms the layer-number dependent bandgap, which is also corroborated by first-principle calculation. In addition, the FL SnSe shows a transition from saturable absorption to reverse saturable absorption with the increase of pumping power, and the nonlinear absorption is characterized by an ultrafast response time of picosecond scale. The nonlinear optical response in FL SnSe could be explained by defect-involved recombination of photogenerated carriers as well as the Auger scattering process, which is further enhanced by structural two-dimensionality.
关键词： nonlinear optics,phosphorene analogue,SnSe,liquid-phase exfoliation,2D semiconductors
更新于2025-09-23 15:23:52
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Ultrathin GeSe Nanosheets: from Systematic Synthesis, to Studies of Carrier Dynamics and Applications for High Performance UV-Vis Photo-Detector
摘要： Owing to the attractive energy band properties, black phosphorus (BP)-analogue semiconductor, germanium selenide (GeSe), shows a promising potential applied for optoelectronic devices. Herein, ultrathin GeSe nanosheets were systematically prepared via a facile liquid phase exfoliation (LPE) approach, with controllable nano-scale thickness. Different from BP, ultrathin GeSe nanosheets exhibits a good stability under both liquid and ambient conditions. Besides, its ultrafast carrier dynamics was probed by transient absorption spectroscopy. We showed that the GeSe nanosheets-based photo-detector exhibits excellent photoresponse behaviors ranging from ultraviolet (UV) to the visible regime, with high responsivity and low dark current. Furthermore, the detective ability of such a device can be effectively modulated by varying the applied bias potential, light intensity and concentration of electrolyte. Generally, our present contribution could not only supply fundamental knowledge of GeSe nanosheets-based photoelectrochemical (PEC)-type device, but also offer a guidance to extend other possible semiconductor materials in the application of PEC-type photo-detector.
关键词： photoelectrochemical,photo-detector,liquid phase exfoliation,carrier dynamics,GeSe nanosheets
更新于2025-09-23 15:23:52
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The transmittance and sheet resistance of chemically and heat reduced graphene oxide film
摘要： The graphene oxide (GO) sheets were prepared from Hummer’s method. The reduced process is important to graphene related materials for widely functional use in many photo-electric fields. Chemically and heat reduced treatment are carried out in this research and the electrical and optical properties of reduced GO films are measured. The size of GO sheets was examined by transmission electron microscopy with a size of about 5–6 μm. The chemically converted graphene (CCG) film are made by spin coating method. We used different GO concentration and different spin coating times to investigate the properties of graphene transparent conductive films. As the decrease of the GO concentration of solution and the times of spin coating, the transmittance is higher. The electrical property of the mixing of GO and CCG is more stable than the GO sheets only, this is discussed in this research and it is cause by the stacking condition of sheets. The conductivity of reduced graphene oxide film come from GO is lower than that come from CCG, we suppose that is because that the overlapping is less (i.e. film-forming ability) in the former, the transmittance and sheet resistance are 56 T% and 50 kohm/sq.
关键词： Graphene oxide,Electrical property,Liquid-phase exfoliation,Transparent conductive films,Chemical reduced graphene oxide
更新于2025-09-23 15:21:21
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Liquid Phase Exfoliated Indium Selenide Based Highly Sensitive Photodetectors
摘要： Layered semiconductors of the IIIA–VIA group have attracted considerable attention in (opto)electronic applications thanks to their atomically thin structures and their thickness-dependent optical and electronic properties, which promise ultrafast response and high sensitivity. In particular, 2D indium selenide (InSe) has emerged as a promising candidate for the realization of thin-film field effect transistors and phototransistors due to its high intrinsic mobility (>102 cm2 V?1 s?1) and the direct optical transitions in an energy range suitable for visible and near-infrared light detection. A key requirement for the exploitation of large-scale (opto)electronic applications relies on the development of low-cost and industrially relevant 2D material production processes, such as liquid phase exfoliation, combined with the availability of high-throughput device fabrication methods. Here, a β polymorph of indium selenide (β-InSe) is exfoliated in isopropanol and spray-coated InSe-based photodetectors are demonstrated, exhibiting high responsivity to visible light (maximum value of 274 A W?1 under blue excitation 455 nm) and fast response time (15 ms). The devices show a gate-dependent conduction with an n-channel transistor behavior. Overall, this study establishes that liquid phase exfoliated β-InSe is a valid candidate for printed high-performance photodetectors, which is critical for the development of industrial-scale 2D material-based optoelectronic devices.
关键词： photodetectors,2D semiconductors,indium selenide,field effect transistors,liquid phase exfoliation,spray coating,solution processed
更新于2025-09-23 15:19:57
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Liquid phase exfoliation of MoS2 and WS2 in aqueous ammonia and their application in highly efficient organic solar cells
摘要： Simple, scalable and cost-effective synthesis of quality two-dimensional (2D) transition metal dichalcogenides (TMDs) is critical for fundamental investigations but also for the widespread adoption of these low-dimensional materials to an expanding range of device applications. Here, we report on the liquid-phase exfoliation (LPE) of molybdenum disulfide (MoS2) and tungsten disulfide (WS2) in aqueous ammonia (NH3 (aq)) as a greener alternative to commonly used but less environmentally friendly solvents. The synthesized nanosheets can be prepared in high concentrations (0.5-1 mg mL-1) and exhibit excellent stoichiometric and structural quality with a semiconducting character. These characteristics makes them ideal for application in organic optoelectronics, where optical transparency and suitable energetics are two important prerequisites. When MoS2 and WS2 are used as the sole hole transport layer materials in organic photovoltaics, cells with power conversion efficiency of 14.9 and 15.6%, respectively, are obtained highlighting the potential of the aqueous ammonia-based LPE method for the preparation of high quality TMDs. The method could potentially be extended to other TMDs.
关键词： aqueous ammonia,MoS2,liquid-phase exfoliation,organic solar cells,WS2
更新于2025-09-23 15:19:57
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A self-powered photodetector based on two-dimensional boron nanosheets
摘要： Owing to their intriguing characteristics, the ongoing pursuit of emerging mono-elemental two-dimensional (2D) nanosheets beyond graphene is an exciting research area for next-generation applications. Herein, we demonstrate that highly crystalline 2D boron (B) nanosheets can be efficiently synthesized by employing a modified liquid phase exfoliation method. Moreover, carrier dynamics has been systematically investigated by using femtosecond time-resolved transient absorption spectroscopy, demonstrating an ultrafast recovery speed during carrier transfer. Based on these results, the optoelectronic performance of the as-synthesized 2D B nanosheets has been investigated by applying them in photoelectrochemical (PEC)-type and field effect transistor (FET)-type photodetectors. The experimental results revealed that the as-fabricated PEC device not only exhibited a favourable self-powered capability, but also a high photoresponsivity of 2.9–91.7 μA W?1 in the UV region. Besides, the FET device also exhibited a tunable photoresponsivity in the range of 174–281.3 μA W?1 under the irradiation of excited light at 405 nm. We strongly believe that the current work shall pave the path for successful utilization of 2D B nanosheets in electronic and optoelectronic devices. Moreover, the proposed method can be utilized to explore other mono-elemental 2D nanomaterials.
关键词： two-dimensional boron nanosheets,optoelectronic devices,carrier dynamics,liquid phase exfoliation,photodetector
更新于2025-09-23 15:19:57
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Molybdenum Disulfide Nanosheet/Quantum Dot Dynamic Memristive Structure Driven by Photoinduced Phase Transition
摘要： MoS2 2D nanosheets (NS) with intercalated 0D quantum dots (QDs) represent promising structures for creating low-dimensional (LD) resistive memory devices. Nonvolatile memristors based 2D materials demonstrate low power consumption and ultrahigh density. Here, the observation of a photoinduced phase transition in the 2D NS/0D QDs MoS2 structure providing dynamic resistive memory is reported. The resistive switching of the MoS2 NS/QD structure is observed in an electric field and can be controlled through local QD excitations. Photoexcitation of the LD structure at different laser power densities leads to a reversible MoS2 2H-1T phase transition and demonstrates the potential of the LD structure for implementing a new dynamic ultrafast photoresistive memory. The dynamic LD photomemristive structure is attractive for real-time pattern recognition and photoconfiguration of artificial neural networks in a wide spectral range of sensitivity provided by QDs.
关键词： neuromorphic computing,photoinduced phase transition,2D crystals and QDs,dynamic photomemristors,liquid phase exfoliation
更新于2025-09-19 17:13:59
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Transferrable thin film of ultrasonically exfoliated MoSe2 nanocrystals for efficient visible-light photodetector
摘要： Two-dimensional transition metal dichalcogenides (2D TMDC’s) materials are the impactful candidates in nanotechnology for diverse applications such as electrocatalyst, sensing and energy storage. Many efforts have been accomplished to solve the problem of green production with the scaling of TMDCs materials. Here we demonstrated the two-step method including electrophoresis deposition (EPD) and direct transfer of MoSe2 nanocrystals (NCs) thin film for fabricating visible-light photodetector. High-resolution transmission electron microscopy and atomic force microscopy show that the liquid exfoliated MoSe2 NCs exhibits good crystalline nature with multi-layered thickness. Raman spectra, UV-Visible spectra, and X-ray photoelectron spectroscopy confirm the presence of 2H-phase of MoSe2 NCs. EPD deposited thin film is detached by dipping into the water and transferred onto the etched ITO substrate. Ag/MoSe2 NCs/ITO photodetector is fabricated which demonstrated the excellent performance in the visible range and demonstrate remarkable values of responsivity, EQE (%) and specific detectivity of 566 mAW-1, 155 % and 3.69 × 1011 Jones. Considering our results, the fabrication technique along with the photoresponse application of TMDC NCs presented here is the innovative and efficient way for developing the large-area optoelectronic devices.
关键词： MoSe2 nanocrystals,Liquid-phase exfoliation,Electrophoresis,Visible-light photodetector
更新于2025-09-19 17:13:59
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Photovoltaic activity of WSe2/Si hetero junction
摘要： Propelled by the development of layered transition metal dichalcogenides, heterojunctions have captivated tremendous attention due to various excitonic mechanisms assisted strong light-matter interaction. We demonstrate liquid phase exfoliation of WSe2 and fabrication of fast switchable WSe2/Si heterojunction. The heterojunction device showed obvious rectifying nature with ideality factor of 1.21 and it is explored under white illumination at power intensities varying from 5 to 18 mW/cm2. The WSe2/Si heterojunction photovoltaic device exhibited excellent transient photoresponse with highest responsivity of 86.11 mA/W and 23 ms response time under white light. Besides, heterojunction exhibited excellent photoresponse in broad spectral range from 390 to 1088 nm with highest photoresponsivity of 122.2 mA/W for 780 nm illumination. The device showed excellent response in temperature range 200 to 300 K. Eventually, the results advocate the huge significance of WSe2/Si heterojunction for photovoltaic cell and photodetection.
关键词： WSe2/Si heterojunction,Responsivity,Liquid phase exfoliation,Photovoltaic activity,Morse codes
更新于2025-09-16 10:30:52