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Synthesis of near unity photoluminescence CdSeTe alloyed Quantum Dots
摘要： Quantum dots (QD) tend to exhibit low photoluminescence (PL) properties due to long hanging ligands on their surface and steric barriers resulting therefrom. On the other hand, in order to be used in QD LED and QDSSC technologies, highly intense PL characteristics and PL lifetime are required respectively. Therefore, this study focuses on increasing the PL QY and PL lifetime of CdSeTe alloy QDs. To achieve this aim, CdSeTe alloy QDs synthesized by organometallic method were treated with different mass % (m/m) chloride solution. The PL Quantum Yield (PL QY) of CdSeTe alloy QDs, which was 13.2 ± 2.0% before treatment, increased to 97.4 ± 2.0% after treatment with 60% CdCl2 solution approaching to almost unity value. In addition to the increase in PL QY, PL lifetime increased from 28 ns to 33 ns with chloride treatment. However, thanks to surface passivation, the time to fall to half the value of PL QY for treated CdSeTe(Cl) QDs under oxygen exposure was increased from 10 h to 64 h. In the study, the absorbance and emission characterizations of CdSeTe alloy QDs treated with chloride and untreated, were presented.
关键词： Quantum dot,Photo luminescence,CdSeTe,Chloride treatment,Quantum yield
更新于2025-11-14 15:24:45
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Surface Plasmon Resonance Enhancement of PbS Quantum Dot-Sensitized Solar Cells
摘要： Lead sulfide (PbS)-sensitized quantum dot solar cells (QDSC) were fabricated using TiO2 and TiO2–Au plasmonic nanocomposite films by successive ionic layer adsorption and reaction (SILAR) method. The average size of gold nanoparticles (GNPs) used for fabricating nanocomposite films was ~ 15 nm. Thin plasmonic QDSC, with a film thickness of 10 μm, showed an increase of ~ 11% in photocurrent and ~ 6% in overall energy conversion efficiency compared to the device without GNPs. The improved performance of QDSCs is attributed to the increased absorption due to the plasmonic near-field effects of the incorporated GNPs. High-efficiency PbS/CdS-co-sensitized thick cells with 16 μm bilayer TiO2 also showed improvement in photocurrent and efficiency. The results show that the plasmonic-enhanced absorption can be used to augment efficiency of QDSC devices in much the same fashion as that of dye-sensitized solar cells.
关键词： Gold nanoparticles,Quantum dot-sensitized solar cells,Plasmonics,Photovoltaics
更新于2025-10-22 19:40:53
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Fabrication of Remarkably Bright QD Densely-Embedded Silica Nanoparticle
摘要： We developed a synthesis method for silica-coated quantum dot (QD)-densely-embedded silica nanoparticle (Si@D-QD@Si NP) with remarkably brighter fluorescence by increasing the number of QDs on silica NPs. Si@D-QD@Si NPs exhibited a narrow size distribution and a high signal reproducibility. Red, green, and blue Si@D-QD@Si NPs were successfully fabricated and characterized. The Si@D-QD@Si NP carried 2.4 times more QDs than previously reported silica-coated QD-embedded silica NP (Si@QD@Si NP). The quantum yield of Si@D-QD@Si NPs was slightly higher than Si@QD@Si NPs. The red Si@D-QD@Si NPs showed approximately 26.6%, the green Si@D-QD@Si NP 36.2%, and the blue Si@D-QD@Si NP 39.3% higher fluorescence intensity compared to the corresponding Si@QD@Si NPs. This result implied that the particles can be used at bio-field with a higher sensitive detection.
关键词： Quantum dot,Quantum yield,Fluorescence,Silica coating,Silica nanoparticle
更新于2025-09-23 15:23:52
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Highly Luminescent Nitrogen-Doped Carbon Dots as “Turn-On” Fluorescence Probe for Selective Detection of Melamine
摘要： In our work, a new and simple method for selective detection of melamine is established by developing a "turn-on" fluorescence probe based on nitrogen-doped carbon dots (N-CQDs). The N-CQDs have been facilely prepared by one-step simple hydrothermal reaction and it is highly luminescent that with 51% fluorescent quantum yield. In this sensor, the fluorescent intensity of N-CQDs was found to be efficient quenched by Fe3+, upon addition of melamine the fluorescent intensity of N-CQDs-Fe3+ could gradually recover, which may because of the competitive combination of Fe3+ and melamine leading to the departure of Fe3+ from the N-CQDs' surface. Under optimum conditions, the fluorescence intensity has a good liner relationship with melamine in the range of 2.0 to 290 μM. The probe displayed good sensitivity toward melamine with a lower detection limit of 0.67 μM. In addition, this fluorescence probe has been used for the analysis of milk samples, demonstrating the fluorescence probe has potential application in the detection of melamine.
关键词： selective detection,turn-on fluorescence probe,melamine,carbon quantum dot
更新于2025-09-23 15:23:52
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Design of a novel reversible structure for full adder/subtractor in quantum-dot cellular automata
摘要： Complementary Metal Oxide Semiconductor (CMOS) technology uses voltage levels for binary computation, whereas Quantum Dot-Cellular Automata (QCA) uses free electron location in the QCA cell for logic evaluation. This technology suggests very low power consumption, high speed and very dense structure for performing any logical circuit. Reversible logic is best mechanism with low power and high speed in circuit designing. Reversible gates have N input and N output lines that input lines mapped with output lines one by one. In this paper, a novel design of Reversible Full adder/subtractor with minimum number of cells has been proposed. QCADesigner software has been used to simulate the proposed design.
关键词： Quantum-dot Cellular Automata (QCA),Reversible Full adder/subtractor
更新于2025-09-23 15:23:52
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Effects of two-photon absorption on pseudo-random bit sequence operating at high speed
摘要： The effect of two-photon absorption (TPA) on all-optical logic operation in quantum-dot semiconductor optical amplifier (QD-SOA) has been carried out. We model the rate equation with the TPA effect for the logic XOR gate, AND gate, and, for pseudo-random bit sequence (PRBS) generation. The simulated results indicate that the TPA induced pumping increases the output Q-factor (quality). The results show that the quality of the output depends on the input pulse width and the speed of operation. The PRBS system can operate at 250 and 320 Gb/s but an increase in pulse width decreases the output Q-factor.
关键词： quantum-dot semiconductor optical amplifier,pseudorandom bit sequence,optical logic,Q factor,Two-photon absorption
更新于2025-09-23 15:23:52
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Efficient optical gain in CdSe/CdS Dot-in-Rod nanocrystals
摘要： Excitonic state-resolved pump/probe spectroscopy is performed on semiconductor dot-in-rod nanocrystals. Using excitonic state-resolved pumping we are able to resolve effects of the rod upon exciton dynamics of the core. The shell has the effect of lowering gain threshold, increasing absorption cross-section, and increasing the Auger lifetime, hence nanorods are shown to be an effective means of enhancing gain performance of nanomaterials.
关键词： nanocrystal,excitons,Auger processes,Quantum dot,optical gain,multiexcitons.
更新于2025-09-23 15:23:52
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Smartphone-Based Fluorescent Lateral Flow Immunoassay Platform for Highly Sensitive Point-of-Care Detection of Zika Virus Nonstructural Protein 1
摘要： Simple, inexpensive, and rapid diagnostic tests in low-resource settings with limited laboratory equipment and technical expertise are instrumental in reducing morbidity and mortality from epidemic infectious diseases. We developed a smartphone-based fluorescent lateral flow immunoassay (LFIA) platform for the highly sensitive point-of-care detection of Zika virus nonstructural protein 1 (ZIKV NS1). An attachment was designed and 3D-printed to integrate the smartphone with external optical and electrical components, enabling the miniaturization of the instrument and reduction in cost and complexity. Quantum dot microspheres were utilized as probes in fluorescent LFIA because of their extremely bright fluorescence signal. This approach can achieve quantitative point-of-care detection of ZIKV NS1 within 20 min. Limits of detection (LODs) in buffer and serum were 0.045 and 0.15 ng mL-1, respectively. Despite the high structural similarity, a high-level Dengue virus NS1 as interferent showed limited cross-reactivity. Furthermore, this assay was successfully applied to detecte ZIKV NS1 and virions spiked in complex biological samples, indicating its practical application capability. Given its low cost, compact size, and excellent analytical performance, the proposed smartphone-based fluorescent LFIA platform holds considerable potential in rapid and accurate point-of-care detection of ZIKV NS1 and provides new insight into the design and application of molecular diagnostic methods in low-resource settings.
关键词： Quantum dot microsphere,Smartphone,Lateral flow immunoassay,Zika virus nonstructural protein 1,Point-of-care
更新于2025-09-23 15:23:52
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Charge transport in graphene-based mesoscopic realizations of Sachdev-Ye-Kitaev models
摘要： We consider a recent proposal for a physical realization of the Sachdev-Ye-Kitaev (SYK) model in the zeroth-Landau-level sector of an irregularly shaped graphene flake. We study in detail charge transport signatures of the unique non-Fermi-liquid state of such a quantum dot coupled to noninteracting leads. The properties of this setup depend essentially on the ratio p between the number of transverse modes in the lead M and the number of the fermion degrees of freedom N on the SYK dot. This ratio can be tuned via the magnetic field applied to the dot. Our proposed setup gives access to the nontrivial conformal-invariant regime associated with the SYK model as well as a more conventional Fermi-liquid regime via tuning the field. The dimensionless linear-response conductance acquires distinct p dependencies for the two phases, respectively, in the low-temperature limit, with a universal jump at the transition. We find that corrections scale linearly and quadratically in either temperature or frequency on the two sides of the transition. In the weak-tunneling regime, we find differential conductance proportional to the inverse square root of the applied voltage bias U for bias energy eU larger than temperature scale kB T. This dependence is replaced by a conventional Ohmic behavior with constant conductance proportional to 1/sqrt(T) for bias energy eU smaller than temperature scale kB T. We also describe the out-of-equilibrium current-bias characteristics and discuss various crossovers between the limiting behaviors mentioned above.
关键词： Sachdev-Ye-Kitaev model,tunneling conductance,graphene,quantum dot,charge transport,non-Fermi-liquid,conformal invariance
更新于2025-09-23 15:23:52
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[IEEE 2018 International Flexible Electronics Technology Conference (IFETC) - Ottawa, ON, Canada (2018.8.7-2018.8.9)] 2018 International Flexible Electronics Technology Conference (IFETC) - Comparative analysis of 1-bit memory cell in CMOS and QCA technology
摘要： Circuit designing with quantum dot cellular automata is one of the most recent technologies which aim at scaling of devices. In this logic design technique, the organization of quantum cells defines the circuit. It is based on field coupled computing. The quantum dot cellular automata has numerous advantages including less area occupied, lack of interconnects, higher clock frequency, and since it doesn't involve transfer of electrons or flow of current, it has the potential to perform low power calculation.This paper presents the comparison of 1-bit memory cell designed using CMOS technology and quantum dot cellular technology. The quantum dot cellular technology results in lesser occupied area at high clock frequency.
关键词： Static Random Access memory,Quantum dot cellular automata,eleven input majority gates
更新于2025-09-23 15:22:29