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- 实验方案
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Generation of large-scale W states in a cavitya??quantum dot system
摘要： We present a scheme for generating large-scale W states based on an expansion mechanism in a cavity–quantum dot system. In cases in which the number of particles is even (2n), the probability of success will be 1.0. In cases in which the number is odd (2n ? 1), the probability of success will be 1 ? 1/2n. As the number of particles increases, the probability of success is closer to 1. Meanwhile, the fidelity of the obtained state decreases slowly as the number of particles increases. Numerical simulation and discussions show that the scheme can be implemented in the current experimental technology.
关键词： cavity–quantum dot system,large-scale W states,expansion mechanism
更新于2025-09-23 15:19:57
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Enhanced current density of anatase TiO2 nanowire arrays by interface connection modulation in flexible quantum dot sensitized solar cells
摘要： The stability and photovoltaic conversion efficiency are very important issues for the industry application of flexible solar cells, which have been seriously limited by the interface connection of basic photo-electrodes in solar cells. Here, one-dimensional TiO2 nanowire arrays films were employed as photo-electrodes of flexible solar cells, which have modulated interface connection of the photo-electrodes by introducing small size of nanoparticles and heating pressure process. The charge generation and separation properties of photo-electrodes have been influenced, which may be attributed by the changes on band energy of small size of nanoparticles in photo-electrodes. With the improvement on the interface connection in the photo-electrodes, the charge transfer property has been effectively improved, which have exhibited a higher current density value of the solar cells, achieving photovoltaic conversion efficiency enhancement from 2.55% to 3.90%. Moreover, there have no obvious changes on the photovoltaic conversion efficiency of these flexible QDSSCs solar cells under the curling condition.
关键词： Anatase TiO2 nanowire arrays,Flexible quantum dot sensitized solar cell,Interface connection,Photovoltaic performance enhancement,Small size of nanoparticles,Heating pressure
更新于2025-09-23 15:19:57
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Emerging Atomic Energy Levels in Zero-Dimensional Silicon Quantum Dots
摘要： Driven by the emergence of colloidal semiconductor quantum dots (QDs) of tunable emission wavelengths, characteristic of exciton absorption peaks, outstanding photostability and solution processability in the development of device fabrication have become a key tool in nanomedicine and optoelectronics. Diamond cubic crystalline silicon (Si) QDs, with a diameter larger than 2 nm, terminated with hydrogen atoms are known to exhibit bulk-inherited spin and valley properties. Herein, we demonstrate a newly discovered size region of Si QDs, in which a fast radiative recombination on the order of hundreds of picoseconds is responsible for photoluminescence (PL). Despite retaining a crystallographic structure like the bulk, controlling their diameters in the 1.1?1.7 nm range realizes the strong PL with continuous spectral tunability in the 530?580 nm window, the narrow spectral line widths without emission tails, and the fast relaxation of photogenerated carriers. In contrast, QDs with diameters greater than 1.8 nm display the decay times on the microsecond order as well as the previous Si QDs. In addition to the five-orders-of-magnitude variation in the PL decay time, a systematic study on the temperature dependence of PL properties suggests that the energy structure of the smaller QDs does not retain an indirect band gap character. It is discussed that a 1.7 nm diameter is critical to undergo changes in energy structure from bulky to molecular configurations.
关键词： Decay dynamics,Size matters,Silicon,Photoluminescence,Quantum dot
更新于2025-09-23 15:19:57
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Graphene Quantum Dot Reinforced Electrospun Carbon Nanofiber Fabrics with High Surface Area for Ultra-High Rate Supercapacitors
摘要： High surface area, good conductivity, and high mechanical strength are important for carbon nanofiber fabrics (CNFs) as high-performance supercapacitor electrodes. However, it remains a big challenge because of the trade-off between the strong and continuous conductive network and well-developed porous structure. Herein, we report a simple strategy to integrate these properties into the electrospun CNFs by adding graphene quantum dots (GQDs). The uniformly embedded GQDs play a crucial bi-functional role in constructing entire reinforcing phase and conductive network. Compared with the pure CNF, the GQD-reinforced activated CNF exhibits a greatly enlarged surface area from 140 to 2032 m2 g-1 as well as significantly improved conductivity and strength of 5.5 and 2.5 times, respectively. The mechanism of robust reinforcing effect is deeply investigated. As freestanding supercapacitor electrode, the fabric performs high capacitance of 335 F g-1 at 1 A g-1 and extremely high capacitance retentions of 77% at 100 A g-1 and 45% at 500 A g-1. Importantly, the symmetric device can be charged to 80% capacitance within only 2.2 s, showing great potential for high-power startup supplies.
关键词： graphene quantum dot,carbon nanofiber,ultra-high rate,high surface area,supercapacitor
更新于2025-09-23 15:19:57
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Dielectric Measurements of Polymer Composite Based on CdS Quantum Dots in Low Density Polyethylene at Microwave Frequencies
摘要： CdS nanoparticles (NPs) as quantum dots (QDs) added into low density polyethylene (LDPE) can significantly change the MW dielectric properties of the composites. Introducing into the matrix of low density polyethylene CdS QDs increase the dielectric constant of more than twice. CdS QDs with concentration of 5 wt % to 20 wt % were prepared by the method of high-speed thermal decomposition. The size of CdS nanoparticles ranged from 2 nm to 7 nm. Experimental samples based on polymer-based nanocomposite in the form of thick films with a thickness of 80 to 100 microns were prepared by thermocompression. Complex dielectric permittivity of thick film samples was measured by T/R method from 2 to 8 GHz at room temperature (25°C). For samples with 20 wt % CdS NPs size effect was found. The change of dielectric properties of polymer composite materials is associated with the size of QDs. The dielectric constant and dielectric loss increases with decreasing size of the quantum dots. It is shown that the highest mean value of the dielectric constant and dielectric loss at a frequency range of 5 GHz to 8 GHz for cadmium sulfide nanoparticles with size of 4 nm were 12 and 189 dB/m, respectively. For QDs with ones of 6 nm average dielectric constant and dielectric loss were 5.8 and 134 dB/m, respectively. The effective dielectric constant and dielectric losses in the microwave range can be changed by CdS QDs of different sizes what consequently increases the possibility of using polymer nanocomposites as core elements of the microwave band-pass filters for various purposes.
关键词： quantum dot,cadmium sulfide,polymer composite,filled polymer,MW dielectric properties,low density polyethylene,composites
更新于2025-09-23 15:19:57
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Poly(acrylamide- <i>co</i> -acrylic acid) gel polymer electrolyte incorporating with water-soluble sodium sulfide salt for quasi-solid-state quantum dot-sensitized solar cell
摘要： Rapid decay of photoanode, leakage from sealant, and evaporation of electrolyte are always the major concerns of quantum dot-sensitized solar cells (QDSCs) based on liquid electrolyte. Subsequently, gel polymer electrolyte (GPE) appears as an attractive solution in addition to lower cost, lighter weight, and flexibility. Poly(acrylamide-co-acrylic acid) (PAAm-PAA) is of special interest to act as a polymer host to entrap liquid electrolyte because it provides high transparency, good gelatinizing properties, and excellent compatibility with the liquid electrolyte. In this work, the electrical and transport properties of PAAm-PAA GPE incorporating with water-soluble sodium sulfide were characterized by impedance spectroscopy. An increment of ionic conductivity was observed with the incorporation of ethylene carbonate (EC) and potassium chloride (KCl). The highest room temperature ionic conductivity of PAAm-PAA GPE is 70.82 mS·cm?1. QDSC based on PAAm-PAA GPE with the composition of 1.3 wt% of KCl, 0.9 wt% of EC, 55.3 wt% of PAAm-PAA, 38.5 wt% of sodium sulfide, and 4.0 wt% of sulfur can present up to 1.80% of light-to-electricity conversion efficiency.
关键词： gel polymer electrolyte,additive,Poly(acrylamide-co-acrylic acid),quantum dot-sensitized solar cells
更新于2025-09-23 15:19:57
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Novel synthesis of Cu2CoSnS4-carbon quantum dots (CCTS:CQD) nano-composite potential light absorber for hybrid photovoltaics
摘要： A novel and simple synthesis of the absorber layer is indispensable in order to reduce the cost and processing of quantum solar cells. In this work, we developed novel Cu2CoSnS4-carbon quantum dot (CCTS:CQD) nano-composite as an absorbing material for solar cell applications. CCTS:CQD nano-composites were prepared by direct pyrolysis of CCTS precursors and citric acid. The proportions of citric acid precursor to CCTS were varied from 0.1 to 0.7. The properties of the synthesized nano-composite were studied using a UV-Vis spectrophotometer in the wavelength range of 300-900 nm. CCTS:CQD has a property of dynamic photoluminescence that depends on the excitation wavelength. The results of the X-ray diffraction revealed that the CCTS:CQD nano-composites were predominantly polycrystalline in nature. The formation of CCTS:CQD was confirmed by a high-resolution transmission electron microscope (HRTEM), which exhibits the size ~3 nm. The thin films of CCTS:CQD nano-composites were deposited on glass/ITO substrates by spray pyrolysis technique at 170 °C. Current-voltage (I-V) measurements carried out in dark and light conditions revealed CCTS:CQD thin films with good photo-response. The purpose of the present study is to develop CCTS:CQD nano-composite p-type absorber layer suitable for thin film solar cells.
关键词： quantum dot,photo-response,Thin Films,Nano-composites,Absorber
更新于2025-09-23 15:19:57
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Influences of Rashba Spin-Orbit Coupling on First Excited State of Magnetopolaron in Parobolic Quantum Dot
摘要： The properties of the first excited state of a magnetopolaron in a patabolic quantum dot (PQD) are studied with the Lee-Low-Pines unitary transformation (LLPUT) and variational method of Pekar-type (VMPT). We find that the external magnetic field and the motion of the electron can trigger the Rashba effect in the first excited state and they play a virtual role in determining properties of the magnetopolaron in the parabolic PQD system. Furthermore, our results indicate the Rashba spin-orbit coupling(RSOC), confined potential, electron-phonon coupling, magnetic field and phonon wave vector promote a variation of the first excited state energy (FESE). In addition, the rule that the first excited state energy changes with one of four factors is not affected by the RSOC.
关键词： First excited state energy,Magnetopolaron,Rashba spin-orbit interaction,Quantum dot
更新于2025-09-23 15:19:57
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Plasmonic Quantum Dot Nanocavity Laser: Hybrid Modes
摘要： The hybrid modes in the plasmonic quantum dot (QD) laser are modeled using the Marctili method. The model is then used to study the mode characteristics. The modes are going to cutoff point at zero propagation constant, while it goes to surface plasmon polaritons (SPPs) mode at higher photon energy. This behavior was different from that of waveguide modes shown in the dielectric waveguide. At plasmon resonance, hybrid mode is exactly one mode: surface plasmon polariton mode (perfect electric conductor).
关键词： Quantum dot,Nanolaser,Hybrid modes,Surface plasmon polariton
更新于2025-09-23 15:19:57
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Electromagnetically induced grating in semiconductor quantum dot and metal nanoparticle hybrid system by considering nonlocality effects
摘要： The optical polarization from a hybrid system including a closely spaced spherical SQD (modeled as a three-level V-type system) and a metal nanoparticle which are considered classically and are connected by the dipole–dipole interaction mechanism is investigated. The interaction between the SQD and the MNP shows an interesting optical response. In the weak probe field regime and MNP nonlocality correction, the absorption spectrum of the hybrid system exhibits an EIT window with two absorption peaks and the plasmon-assisted quantum interference plays an important role in the position and amplitude of these peaks, which are intensely altered by including the nonlocal effects. The probe diffraction grating is created based on the excitons-induced transparency by applying a standing-wave coupling field. The results of this study are useful in numerous areas of all-optical communications.
关键词： Metal nanoparticles (MNP),Hybrid system,Electromagnetically induced grating (EIG),Nonlocality,Semiconductor quantum dot (SQD)
更新于2025-09-23 15:19:57