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oe1(光电查) - 科学论文

110 条数据
?? 中文（中国） ▾

  • Passively Q-switched erbium-doped fiber laser using quantum dots CdSe embedded in polymer film as saturable absorber

    摘要： We demonstrate a passively Q-switched erbium doped fiber laser (EDFL) based on quantum dots (QD) CdSe as a saturable absorber (SA). The synthesized CdSe powder was embedded into a poly(methyl methacrylate) (PMMA) using emulsion polymerization process. The film is sandwiched between two fiber connector via an adapter to form a fiber-compatible SA device. By integrating the SA device into the EDFL ring cavity, the stable Q-switched operation is achieved at 1559.35 nm as the pump power is varied within 30–118 mW. The laser has a pump threshold of 20.4 mW. The pulse repetition rate shows an increasing trend from 33.2 to 68.45 kHz, whereas the pulse width exhibits a decreasing trend from 10.04 to 4.30 μs as the pump power is increased from 30 to 118 mW. The highest pulse energy of 11.83 nJ is obtained at a pump power of 118 mW. These results indicate that QD CdSe is a promising SA for Q-switching laser operation.

    关键词： Q-switching,Quantum dots CdSe,Saturable absorber

    更新于2025-11-28 14:23:57

  • Fluorescence spectra of colloidal self-assembled CdSe nano-wire on substrate of porous Al <sub/>2</sub> O <sub/>3</sub> /Au nanoparticles

    摘要： We present a self-assembly method to prepare array nano-wires of colloidal CdSe quantum dots on a substrate of porous Al2O3 film modified by gold nanoparticles. The photoluminescence (PL) spectra of nanowires are in situ measured by using a scanning near-field optical microscopy (SNOM) probe tip with 100-nm aperture on the scanning near-field optical microscope. The results show that the binding sites from the edge of porous Al2O3 nanopores are combined with the carboxyl of CdSe quantum dots’ surface to form an array of CdSe nanowires in the process of losing background solvent because of the gold nanoparticles filling the nano-holes of porous Al2O3 film. Compared with the area of non-self-assembled nano-wire, the fluorescence on the Al2O3/Au/CdSe interface is significantly enhanced in the self-assembly nano-wire regions due to the electron transfer conductor effect of the gold nanoparticles’ surface. In addition, its full width at half maximum (FWHM) is also obviously widened. The method of enhancing fluorescence and energy transfer can widely be applied to photodetector, photocatalysis, optical display, optical sensing, and biomedical imaging, and so on.

    关键词： porous Al2O3 film,colloidal self-assembled method,CdSe nano-wire,enhanced photoluminescence

    更新于2025-11-25 10:30:42

  • Efficient White LEDs Using Liquid-state Magic-sized CdSe Quantum Dots

    摘要： Magic clusters have attracted significant interest to explore the dynamics of quantum dot (QD) nucleation and growth. At the same time, CdSe magic-sized QDs reveal broadband emission in the visible wavelength region, which advantageously offer simple integration of a single-type of nanomaterial and high color rendering ability for white light-emitting diodes (LEDs). Here, we optimized the quantum yield of magic-sized CdSe QDs up to 22% via controlling the synthesis parameters without any shelling or post-treatment process and integrated them in liquid-state on blue LED to prevent the efficiency drop due to host-material effect. The fabricated white LEDs showed color-rendering index and luminous efficiency up to 89 and 11.7 lm/W, respectively.

    关键词： Magic clusters,Quantum dots,Luminous efficiency,CdSe,White light-emitting diodes

    更新于2025-11-20 15:33:11

  • A novel fluorescent probe for H2O2 detection based on CdSe@ZnS quantum dots/Ag nanocluster hybrid

    摘要： The selective and quantitative detection of H2O2 is important for its employment in physiological, environmental and industrial applications. In this paper, a sensitive and selective strategy for H2O2 detection was established based on the fluorescence quenching of CdSe@ZnS quantum dots (QDs) by H2O2-mediated etching process of Ag nanoclusters (AgNCs). In this strategy, dihydrolipoic acid (DHLA) modified AgNCs were applied as H2O2 response group, the existence of H2O2 could initiate the oxidation of AgNCs and the production of Ag+, which could give rise to the effective fluorescence quenching of CdSe@ZnS QDs. Based on this strategy, the present fluorescent assay could realize the quantificational detection of H2O2 and the limit of detection is calculated to be 0.3 mM under the optimum conditions. Furthermore, CdSe@ZnS/AgNCs hybrid-based probe was applied to detecting H2O2 in milk samples and showed a good recoveries results ranged from 95.8% to 112.0%, meaning the potential applicability of this strategy.

    关键词： H2O2 detection,Ag nanoclusters,Fluorescence quenching,CdSe@ZnS quantum dots

    更新于2025-11-19 16:46:39

  • Synthesis of Inorganic-Organic 2D CdSe Slab-Diamine Quantum Nets

    摘要： Porous semiconductors attract great interest due to their unique structural characteristics of high surface area as well as their intrinsic optical and electronic properties. In this study, synthesis of inorganic–organic 2D CdSe slabs-diaminooctane (DAO) porous quantum net structures is demonstrated. It is found that the hybrid 2D CdSe-DAO lamellar structures are disintegrated into porous net structures, maintaining an ultrathin thickness of ≈1 nm in CdSe slabs. Furthermore, the CdSe slabs in quantum nets show the highly shifted excitonic transition in the absorption spectrum, demonstrating their strongly confined electronic structures. The possible formation mechanism of this porous structure is investigated with the control experiments of the synthesis using n-alkyldiamines with various hydrocarbon chain lengths and ligand exchange of DAO with oleylamine. It is suggested that a strong van der Waals interaction among long chain DAO may exert strong tensile stress on the CdSe slabs, eventually disintegrating slabs. The thermal decomposition of CdSe-DAO quantum nets is further studied to form well-defined CdSe nanorods. It is believed that the current CdSe-DAO quantum nets will offer a new type of porous semiconductors nanostructures under a strong quantum-confinement regime, which can be applied to various technological areas of catalysts, electronics, and optoelectronics.

    关键词： quantum nets,porous materials,semiconductor nanocrystals,CdSe,2D materials

    更新于2025-09-23 15:23:52

  • Fluorescence Imaging for Ultrafiltration of Individual Nanoparticles from a Colloidal Solution in Track Membranes

    摘要： We have used ? uorescence nanoscopy for direct imaging of adsorption of individual colloidal quantum dots of diameter ~10 nm (spherical core/shell CdSeS/ZnS semiconductor nanocrystals, functionalized by organic oleic acid ligands) in nanopores of a nuclear ? lter (a polypropylene track membrane with pores of diameter ~500 nm). We have shown that when a colloidal toluene solution passes through the pores of the membrane, the nanoparticles are completely retained at a depth of 10 μm.

    关键词： nanopore,single-photon source,CdSe,membrane,nanoscopy,entangled-photon source,quantum dot,colloidal solution,microscopy,nanoparticles,ultra? ltration,oleic acid,nuclear ? lter,luminescence,polymer

    更新于2025-09-23 15:21:21

  • Estimation of the lateral dimensions of epitaxial submonolayer CdSe/ZnSe quantum dots

    摘要： CdSe fractional monolayer quantum dots (FMQDs) embedded in a ZnSe matrix were produced by atomic layer epitaxy with a nominal coverage of 0.5 monolayer. They have a thickness of a/2, where a is the strained perpendicular lattice constant of cubic CdSe. Their photoluminescence spectra at low temperature exhibit narrow and intense excitonic emission around 2.759 eV. Based on the experimental excitonic emission energy and applying the factorized-envelope approximation, we have estimated that the lateral dimensions of these FMQDs are around 4 - 5 nm and their density is ~ 3 × 1012 cm-2.

    关键词： quantum dots size,fractional monolayer quantum dots,epitaxial quantum dots,submonolayer quantum dots,ultra-thin quantum dots,CdSe quantum dots

    更新于2025-09-23 15:21:01

  • An inverted ZnO/P3HT:PbS bulk-heterojunction hybrid solar cell with a CdSe quantum dot interface buffer layer

    摘要： An inverted bulk-heterojunction (BHJ) hybrid solar cell having the structure ITO/ZnO/P3HT:PbS/Au was prepared under ambient conditions and the device performance was further enhanced by inserting an interface buffer layer of CdSe quantum dots (QDs) between the ZnO and the P3HT:PbS BHJ active layer. The device performance was optimized by controlling the size of the CdSe QDs and the buffer layer thickness. The buffer layer, with an optimum thickness and QD size, has been found to promote charge leading to an increased open-circuit voltage (VOC), extraction and reduces interface recombinations, short circuit current density (JSC), fill factor (FF) and power conversion efficiency (PCE). About 40% increase in PCE from 1.7% to 2.4% was achieved by the introduction of the CdSe QD buffer layer, whose major contribution comes from a 20% increase of VOC.

    关键词： CdSe quantum dots,inverted bulk-heterojunction,interface buffer layer,hybrid solar cell,power conversion efficiency

    更新于2025-09-23 15:21:01

  • Transition metal nanohybrid as efficient and stable counter electrode for heterostructure quantum dot sensitized solar cells: A trial

    摘要： Counter electrodes are critical components of third generation solar cells. A simple strategy of utilizing iso-structural analogue of graphene, namely 2D molybdenum di-sulphide as nanohybrid with CuS as counter electrode is explored in this work. Formation of heterostructure photoanode with CdSe/CdS quantum dots along with nano-hybrid counter electrode has significantly boosted current density and open circuit voltage. The designed heterostructure and the counter electrode performs exceptionally well with good stability due to synergistic effect, thus spiking new hopes in achieving high efficiency in quantum dot solar cells.

    关键词： Hall effect,CuS-MoS2 nanohybrid,CdSe/CdS heterostructures,Mobility

    更新于2025-09-23 15:21:01

  • Phonon-Driven Energy Relaxation in PbS/CdS and PbSe/CdSe Core/Shell Quantum Dots

    摘要： We study the impact of the chemical composition on phonon-mediated exciton relaxation in the core/shell quantum dots (QDs), with 1-nm core made of PbX and the monolayer shell made of CdX, where X=S and Se. For this, time-domain non-adiabatic dynamics (NAMD) based on Density Functional Theory (DFT) and Surface Hopping techniques are applied. Simulations reveal twice faster energy relaxation in PbS/CdS than PbSe/CdSe due to dominant couplings to higher-energy optical phonons in structures with sulfur anions. For both QDs, the long-living intermediate states associated with the core-shell interface govern the dynamics. Therefore, a simple exponential model is not appropriate, and the four-state irreversible kinetic model is suggested instead, predicting 0.9 ps and 0.5 ps relaxation rates in PbSe/CdSe and PbS/CdS QDs, respectively. Thus, 2-nm PdSe/CdSe QDs with a single monolayer shell exhibit the phonon-mediated relaxation time sufficient for carrier multiplications to outpace energy dissipation and benefit the solar conversion efficiency.

    关键词： Density Functional Theory,phonon-driven energy relaxation,PbSe/CdSe,PbS/CdS,core/shell quantum dots,Surface Hopping techniques,non-adiabatic dynamics

    更新于2025-09-23 15:21:01