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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) - Toward Coupling Color Centers in Single Crystal Diamond to Two-Dimensional Materials
摘要： Individual nitrogen vacancy (NV) color centers in diamond are bright, photo-stable, atomic-sized dipole emitters [1]. Consequently, they represent optimal candidates for novel scanning near field microscopy techniques [2]. Here, NV centers form one member of a F¨orster Resonance Energy Transfer (FRET) pair. Due to their broadband emission (> 100 nm), NVs are versatile donors for FRET to systems absorbing in the near infrared spectral range. Highly-promising applications include, e.g., nanoscale imaging of fluorescent molecules or nanomaterials like graphene [2]. Critical parameters for FRET are the NV’s quantum efficiency, charge state stability and NV-sample-distance. Previous experiments used NVs in nanodiamond for FRET [2], however these NVs might suffer from quenching, instability and badly controlled surface termination. We here address this issue by using shallowly implanted NV centers in optimized cylindrical nanostructures [3] used as scanning probes in our homebuilt combination of a confocal and an atomic force microscope. In recent years, two-dimensional materials especially monolayers of semiconducting materials are of major interest in research. Particularly, dichalcogenides like, e.g., tungsten diselenide (WSe2) are promising candidates for a varity of applications [4]. WSe2 emits photons at a wavelength of around 750 nm while absorbing photons below 700 nm [4] which renders WSe2 as a promising FRET partner for NV centers. Here, we present first results towards demonstrating the interaction of NV color centers in single crystal diamond with WSe2. We envisage using quenching of the NV center sued as a donor in FRET in close proximity to the 2D material as a valuable sensing ressource.
关键词： F¨orster Resonance Energy Transfer (FRET),tungsten diselenide (WSe2),nitrogen vacancy (NV) color centers,diamond,two-dimensional materials
更新于2025-09-11 14:15:04
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Single Source Thermal Evaporation of Two-dimensional Perovskite Thin Films for Photovoltaic Applications
摘要： Hybrid two-dimensional (2D) halide perovskites has been widely studied due to its potential application for high performance perovskite solar cells. Understanding the relationship between microstructural and opto-electronic properties is very important for fabricating high-performance 2D perovskite solar cell. In this work, the effect of solvent annealing on grain growth was investigated to enhance the efficiency of photovoltaic devices with 2D perovskite films based on (BA)2(MA)3pb4i13 prepared by single-source thermal evaporation. Results show that solvent annealing with the introduction of solvent vapor can effectively enhance the crystallization of the (BA)2(MA)3pb4i13 thin films and produce denser, larger-crystal grains. The thin films also display a favorable band gap of 1.896 eV, which benefits for increasing the charge-diffusion lengths. The solvent-annealed (BA)2(MA)3pb4i13 thin-film solar cell prepared by single-source thermal evaporation shows an efficiency range of 2.54–4.67%. Thus, the proposed method can be used to prepare efficient large-area 2D perovskite solar cells.
关键词： solvent annealing,thermal evaporation,two-dimensional perovskite,photovoltaic applications,grain growth
更新于2025-09-11 14:15:04
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Terahertz plasmonics: The rise of toroidal metadevices towards immunobiosensings
摘要： This work reviews fundamentals and the recent state-of-art achievements in the field of plasmonic biosensing based terahertz (THz) spectroscopy. Being nonpoisonous and nondestructive to the human tissues, THz signals offer promising, cost-effective, and real-time biodevices for practical pharmacological applications such as enzyme reaction analysis. Rapid developments in the field of THz plasmonics biosensors and immunosensors have brought many methodologies to employ the resonant subwavelength structures operating based on the fundamental physics of multipoles and asymmetric lineshape resonances. In the ongoing hunt for new and advanced THz plasmonic biosensors, the toroidal metasensors have emerged as excellent alternates and are introduced to be a very promising technology for THz immunosensing applications. Here, we provide examples of recently proposed THz plasmonic metasensors for the detection of thin films, chemical and biological substances. This review allows to compare the performance of various biosensing tools based on THz plasmonic approach and to understand the strategic role of toroidal metasensors in highly accurate and sensitive biosensors instrumentation. The possibility of using THz plasmonic biosensors based on toroidal technology in modern medical and clinical practices has been briefly discussed.
关键词： Two-dimensional,Electrocatalysis,Metallic nanocrystals,Renewable energy
更新于2025-09-11 14:15:04
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Resonant Tunneling Diode (RTD) Terahertz Active Transmission Line Oscillator with Graphene-Plasma Wave and Two Graphene Antennas
摘要： This study describes the design of a resonant tunneling diode (RTD) oscillator (RTD oscillator) with a RTD-gated-graphene-2DEF (two dimensional electron fluid) and demonstrates the functioning of this RTD oscillator through a transmission line simulation model. Impedance of the RTD oscillator changes periodically when physical dimension of the device is of considerable fraction of the electrical wavelength. As long as impedance matching is achieved, the oscillation frequency is not limited by the size of the device. An RTD oscillator with a graphene film and negative differential resistance (NDR) will produce power amplification. The positive electrode of the DC power supply is modified and designed as an antenna. So, the reflected power can also be radiated to increase RTD oscillator output power. The output analysis shows that through the optimization of the antenna structure, it is possible to increase the RTD oscillator output to 22 mW at 1.9 THz and 20 mW at 6.1 THz respectively. Furthermore, the RTD oscillator has the potential to oscillate at 50 THz with a matching antenna.
关键词： transmission line model,RTD-gated-graphene-2DEF,resonant tunneling diode (RTD),graphene-plasma,two-dimensional electron fluid (2DEF),resonant tunneling diode oscillator (RTD oscillator),terahertz
更新于2025-09-11 14:15:04
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High-yield production of stable antimonene quantum sheets for highly efficient organic photovoltaics
摘要： High-performance organic photovoltaics (OPVs) are of great scientific and technological importance due to their potential large-scale industrial applications. Introducing semiconductor quantum dots has been proven to be an effective way to improve the power conversion efficiency (PCE) of OPVs. In this paper, we report a novel approach to fabricate atomically thin antimonene quantum sheets (AMQSs) possessing a uniform size (～2.2 nm) via imidazolium ionic liquid-assisted exfoliation. In this method, the yield of AMQSs (1.1 mg mL?1) has been increased by nearly two orders of magnitude compared with that of previously reported methods. Furthermore, upon adding AMQSs into the light absorber in OPVs, the optimal device with 1.0 mg mL?1 AMQSs shows the highest PCE of 9.75%, resulting in over 25% enhancement in PCE compared to that of the reference device. It also leads to a noticeable enhancement in the short-circuit current density (Jsc) of 16.7% and the fill factor (FF) of 8.4%. The increased PCE is mainly due to the two-dimensional electronic structure of AMQSs that can enhance the light absorption, assist exciton dissociation and reduce charge recombination of OPVs. This work provides a new avenue toward mass production of two-dimensional quantum sheets and points to a new strategy for highly efficient OPVs.
关键词： antimonene quantum sheets,organic photovoltaics,power conversion efficiency,ionic liquid-assisted exfoliation,two-dimensional materials
更新于2025-09-11 14:15:04
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Recent progress in the controlled synthesis of 2D metallic transition metal dichalcogenides
摘要： Two-dimensional (2D) metallic transition metal dichalcogenides (MTMDCs), the complement of 2D semiconducting TMDCs, have attracted extensive attentions in recent years because of their versatile properties such as superconductivity, charge density wave, and magnetism. To promote the investigations of their fantastic properties and broad applications, the preparation of large-area, high-quality, and thickness-tunable 2D MTMDCs has become a very urgent topic and great efforts have been made. This topical review therefore focuses on the introduction of the recent achievements for the controllable syntheses of 2D MTMDCs (VS2, VSe2, TaS2, TaSe2, NbS2, NbSe2, etc.). To begin with, some earlier developed routes such as chemical vapor transport, mechanical/chemical exfoliation, as well as molecular beam epitaxy methods are briefly introduced. Secondly, the scalable chemical vapor deposition methods involved with two sorts of metal-based feedstocks, including transition metal chlorides and transition metal oxidations mixed with alkali halides, are discussed separately. Finally, challenges for the syntheses of high-quality 2D MTMDCs are discussed and the future research directions in the related fields are proposed.
关键词： chemical vapor deposition,metallic transition metal dichalcogenides,synthesis,two dimensional
更新于2025-09-11 14:15:04
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Transparent Collision Visualization of Point Clouds Acquired by Laser Scanning
摘要： Exploring two-dimensional (2D) materials with room-temperature ferromagnetism and large perpendicular magnetic anisotropy is highly desirable but challenging. Here, through first-principles calculations, we propose a viable strategy to achieve such materials based on transition metal (TM) embedded borophene nanosheets. Due to electron deficiency, the commonly existent hexagon boron vacancies in various borophene phases serve as intrinsic anchor points for electron-rich transition metals, which not only adsorb strongly upon the vacancies but also favor to be embedded into the vacancies, forming 2D planar hybrid nanosheets. The adsorption-to-embedding transition is feasible thermodynamically and kinetically, owing to its exothermic nature and relatively small kinetic barriers. After embedding, phase transition is further proposed to obtain diverse structures of TM embedded borophenes with versatile magnetic properties. Based on the example of χ3 phase borophene, several ferromagnetic TM embedded borophene nanosheets with high Curie temperature and large perpendicular magnetic anisotropy have been predicted.
关键词： transition metal embedded borophene nanosheets,first-principles calculations,perpendicular magnetic anisotropy,room-temperature ferromagnetism,two-dimensional materials
更新于2025-09-11 14:15:04
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Dopant-Free Squaraine-Based Polymeric Hole-Transporting Materials with Comprehensive Passivation Effects for Efficient All-Inorganic Perovskite Solar Cells
摘要： Quantum-dot (QD) white light-emitting diodes (LEDs) are promising for illumination and display applications due to their excellent color quality. Although they have a high quantum yield close to unity, the reabsorption of QD light leads to high conversion loss, significantly reducing the luminous efficacy and stability of QD white LEDs. In this report, SBA-15 mesoporous particles (MPs) with two-dimensional hexagonal pore structures (2D-HPS) are utilized to largely enhance the luminous efficacy and color-conversion efficiency of QD white LEDs in excess of 50%. The reduction in conversion loss also helps QD white LEDs to achieve a lifetime 1.9 times longer than that of LEDs using QD-only composites at harsh aging conditions. Simulation and testing results suggest that the waveguide effect of 2D-HPS helps in reducing the reabsorption loss by constraining the QD light inside the wall of 2D-HPS, decreasing the probability of being captured by QDs inside the hole of 2D-HPS. As such, materials and mechanisms like SBA-15 MPs with 2D-HPS could provide a new path to improve the photon management of QD light, comprehensively enhancing the performances of QD white LEDs.
关键词： stability,two-dimensional hexagonal pore structure,reabsorption,luminous efficacy,SBA-15 mesoporous particle,quantum-dot white light-emitting diode
更新于2025-09-11 14:15:04
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Study of Charge Transfer at Quantum Dot-Graphene Interface by Raman Spectroscopy
摘要： Charge transfer at the interface is important for the optoelectronic and photochemical applications of quantum dot-two dimensional material (QD-2D) hybrids. In this work, Raman spectroscopy was exploited to characterize the CdS QD-graphene hybrids with varied thicknesses of graphene and QD layer. The selection of Raman excitation energies below the QD bandgap rules out the photoexcitation effects and thus we can focus on equilibrium charge transfer upon hybrid formation. Correlation analysis of Raman spectra shows evidences of electron transfer with concentration on the order of ~1012 cm-2, confirmed by electrical measurements. The method used in this study can be applied to characterize the interfacial interaction of various QD-2D hybrids.
关键词： hybrid interface,charge transfer,quantum dots,Raman spectroscopy,two-dimensional materials
更新于2025-09-11 14:15:04
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Quantum Multibody Interactions in Halide-Assisted Vapor-Synthesized Monolayer WSe <sub/>2</sub> and Its Integration in a High Responsivity Photodetector with Low-Interface Trap Density
摘要： Among the two-dimensional (2D) transitional-metal dichalcogenides, monolayer (1L) tungsten diselenide (WSe2) has recently attracted a great deal of interest because of its direct band gap and tunable charge transport behavior, making it attractive for a variety of electronic and optoelectronic applications. Controlled and efficient synthesis of 1L WSe2 using chemical vapor deposition (CVD) is often challenging because of the high temperatures required to generate a steady flux of tungsten atoms in the vapor phase from the oxide precursors. Here, the use of halide-assisted low-pressure CVD with NaCl helps to reduce the growth temperature to ～750 °C, which is lower than the typical temperatures needed with conventional CVD for realizing 1L WSe2. Moreover, we experimentally probed the quantum multibody interactions in 1L WSe2 ascribed to excitons, trions, and other localized states by analyzing the temperature-dependent photoluminescence spectra, where such multibody interactions govern the intrinsic electronic and optoelectronic properties of 1L WSe2 for device platforms. The role of the metal?2D semiconductor interface is also critical to realize high-performance devices. In this study, a 1L WSe2-based photodetector was fabricated using Al contacts, which shows a high photoresponsivity, and the interface-state density Dit of the Al/WSe2 junction was computed to be the lowest reported to date ～3.45 × 1012 cm?2 eV?1. Our work demonstrates the tremendous potential of WSe2 to open avenues for state-of-the-art electronic, optoelectronic, and quantum-optoelectronic devices using scalable synthesis routes.
关键词： transitional-metal dichalcogenides,photodetector,tungsten diselenide (WSe2),two-dimensional (2D) materials,quantum multibody interactions,interface-state density,chemical vapor deposition (CVD)
更新于2025-09-11 14:15:04