- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
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
-
Electrochemiluminescent biosensor with DNA link for selective detection of human IgG based on steric hindrance
摘要： A highly selective DNA-based electrochemiluminescence (ECL) based biosensor is described for the detection of human IgG. It is exploiting the effect of steric hindrance that affects the strength of the ECL signal in the presence of IgG. Digoxin-linked signalling DNA was specifically bound to IgG, and this causes steric hindrance which limits the ability of DNA to hybridize with capturing DNA attached to a gold electrode. Europium (II) doped CdSe quantum dots were covalently linked to the DNA in order to generate the ECL signal. Using this steric hindrance hybridization method, the ECL signal of the biosensor were proportional to the concentration of IgG with a wide linear range and a 14 pM detection limit. Conceivably, the method can be expanded to the detection of a wide range of proteins for which homologous recognition elements are available.
关键词： Digoxin-linked signalling DNA,Electrochemiluminescence,Human IgG,Steric hindrance effects,Biosensor,Europium (II) doped CdSe quantum dots
更新于2025-09-23 15:21:01
-
Occurrence control of charged exciton for a single CdSe quantum dot at cryogenic temperatures on an optical nanofiber
摘要： We discuss photo-luminescence characteristics of CdSe core/shell quantum dots at cryogenic temperatures using a hybrid system of a single quantum dot and an optical nanofiber. The key point is to control the emission species of quantum dot to charged excitons, known as trions, which have superior characteristics to neutral excitons. We investigate the photocharging behavior for the quantum dots by varying the wavelength and intensity of irradiating laser light, and establish a method to create a permanently charged situation which lasts as long as the cryogenic temperature is maintained. The present photo-charging method may open a new route to applying the CdSe quantum dots in quantum photonics, and the hybrid system of photocharged quantum-dot and optical nanofiber may readily be applicable to a fiber-in-line single-photon generator.
关键词： Optical nanofiber,Cryogenic temperatures,CdSe quantum dots,Photocharging,Trions
更新于2025-09-23 15:21:01
-
Photocatalytic solar fuel production and environmental remediation through experimental and DFT based research on CdSe-QDs-coupled P-doped-g-C3N4 composites
摘要： Solar energy harvesting and conversion into useful chemical energy with the aid of semiconductor photocatalysts is a promising technique to solve both energy and environmental issues. This work reports a successful synthesis of CdSe quantum dots (QDs) modified phosphorus doped g-C3N4 (P-CN) for advanced photocatalytic applications. Phosphorus doping and structural coupling with CdSe QDs are shown to significantly extend visible-light response of g-C3N4 up to 700 nm. The optimized sample 4CdSe/P-CN demonstrates enhanced visible-light driven overall water splitting activities for H2 and O2 evolution i.e. 113 and 55.5 μmol.h?1.g?1, respectively, as well as very high photocatalytic CO2 to CH4 conversion efficiency (47 μmol.h?1.g?1). It also exhibit higher activity (78 %) for 2,4-dichlorophenol degradation as compared to pristine CN-sample. Combined photoluminescence, transient/single wavelength photocurrent, photoelectrochemical, and coumarin fluorescence spectroscopy demonstrate that 4CdSe/P-CN nanocomposite exhibit enhanced charge separation efficiency which is responsible for improved visible light catalytic activities. Our work thus provide a new strategy to design low-cost and sustainable photocatalysis with wide visible-light activity for practical overall water splitting and CO2 reduction applications.
关键词： Expending visible-light response,g-C3N4,Phosphorus doping,Solar fuel,CdSe quantum dots
更新于2025-09-23 15:21:01
-
Synergistic enhancement in the microelectronic properties of poly-(dioctylfluorene) based Schottky devices by CdSe quantum dots
摘要： This paper reports the potential application of cadmium selenide (CdSe) quantum dots (QDs) in improving the microelectronic characteristics of Schottky barrier diode (SBD) prepared from a semiconducting material poly-(9,9-dioctylfluorene) (F8). Two SBDs, Ag/F8/P3HT/ITO and Ag/F8-CdSe QDs/P3HT/ITO, are fabricated by spin coating a 10 wt% solution of F8 in chloroform and 10:1 wt% solution of F8:CdSe QDs, respectively, on a pre-deposited poly(3-hexylthiophene) (P3HT) on indium tin oxide (ITO) substrate. To study the electronic properties of the fabricated devices, current-voltage (I–V) measurements are carried out at 25 °C in dark conditions. The I–V curves of Ag/F8/P3HT/ITO and Ag/F8-CdSe QDs/P3HT/ITO SBDs demonstrate asymmetrical behavior with forward bias current rectification ratio (RR) of 7.42 ± 0.02 and 142 ± 0.02, respectively, at ± 3.5 V which confirm the formation of depletion region. Other key parameters which govern microelectronic properties of the fabricated devices such as charge carrier mobility (μ), barrier height (φb), series resistance (Rs) and quality factor (n) are extracted from their corresponding I–V characteristics. Norde’s and Cheung functions are also applied to characterize the devices to study consistency in various parameters. Significant improvement is found in the values of Rs, n, and RR by 3, 1.7, and 19 times, respectively, for Ag/F8-CdSe QDs/P3HT/ITO SBD as compared to Ag/F8/P3HT/ITO. This enhancement is due to the incorporation of CdSe QDs having 3-dimensional quantum confinement and large surface-to-volume area. Poole-Frenkle and Richardson-Schottky conduction mechanisms are also discussed for both of the devices. Morphology, optical bandgap (1.88 ± 0.5 eV) and photoluminescence (PL) spectrum of CdSe QDs with a peak intensity at 556 nm are also reported and discussed.
关键词： poly-(9,9-dioctylfluorene),charge carrier mobility,Schottky barrier diode,microelectronic properties,CdSe quantum dots
更新于2025-09-23 15:19:57
-
Coherent Exciton Dynamics in Ensembles of Size-Dispersed CdSe Quantum Dot Dimers Probed via Ultrafast Spectroscopy: A Quantum Computational Study
摘要： Interdot coherent excitonic dynamics in nanometric colloidal CdSe quantum dots (QD) dimers lead to interdot charge migration and energy transfer. We show by electronic quantum dynamical simulations that the interdot coherent response to ultrashort fs laser pulses can be characterized by pump-probe transient absorption spectroscopy in spite of the inevitable inherent size dispersion of colloidal QDs. The latter, leading to a broadening of the excitonic bands, induce accidental resonances that actually increase the efficiency of the interdot coupling. The optical electronic response is computed by solving the time-dependent Schrodinger equation including the interaction with the oscillating electric field of the pulses for an ensemble of dimers that differ by their size. The excitonic Hamiltonian of each dimer is parameterized by the QD size and interdot distance, using an effective mass approximation. Local and charge transfer excitons are included in the dimer basis set. By tailoring the QD size, the excitonic bands can be tuned to overlap and thus favor interdot coupling. Computed pump-probe transient absorption maps averaged over the ensemble show that the coherence of excitons in QD dimers that lead to interdot charge migration can survive size disorder and could be observed in fs pump-probe, four-wave mixing, or covariance spectroscopy.
关键词： coherent electronic dynamics,pump-probe transient absorption spectroscopy,CdSe quantum dots dimers,exciton dynamics,size dispersion effects
更新于2025-09-23 15:19:57
-
CdSe quantum dots-sensitized FRET system for ciprofloxacin detection
摘要： The prepared CdSe quantum dots (QDs) were applied to selectively and sensitively assay ciprofloxacin as a fluorescence sensor based on fluorescence resonance energy transfer (FRET) mechanism. The efficiency of FRET between CdSe QDs and ciprofloxacin can be modulated by the degree of spectral overlap between the excitation peak of CdSe QDs and the emission peak of ciprofloxacin. Within the range of 0 to 120 μmol·L?1, the good linearity was obtained (R = 0.99561) and the detection limit reached to 0.6 μmol·L?1. This method is simple and rapid and can be used in environmental water and milk samples.
关键词： Fluorescent sensor,Semiconductors,Luminescence,Ciprofloxacin,CdSe quantum dots,FRET
更新于2025-09-19 17:13:59
-
Samarium3+-doped CdSe quantum dots for improved electro-optical properties
摘要： Cadmium Selenide (CdSe) quantum dots (QDs) semiconductors having direct band gap exists in different colours which depends on the size of the particles. Doping can be easy in semiconductors but adding impurities in quantum range was always considered as challenging. In the present work, we have carried out studies on the doping of CdSe QDs with Samarium 3+ (Sm3+) impurities. Four different sizes of particles were synthesised by kinetic growth route using 3-mercaptopropionic acid (3-MPA) as the capping agent. The prepared samples were characterized by ultra violet-visible (UV) and photoluminescence (PL) for their optical properties and fourier transform infrared spectroscopy (FTIR) for vibrational studies. The evidence of doping was traced by the results from the optical properties A blue shift in the absorbance spectra was recorded when compared with undoped CdSe QDs. This shift was attributed due to the transfer of energy from the host material to the dopant. The broadband PL spectra covering the entire visible range were recorded for undoped and doped QDs. In undoped CdSe QDs only band edge emission was noticeable, but after incorporating Sm3+ dopant defects were generated in QDs. Sm3+-doped CdSe QDs showed emission spectra including band edge and defect driven emissions.
关键词： Photoluminescence,CdSe Quantum Dots,Samarium doping
更新于2025-09-16 10:30:52
-
Identifying Clusters and/or Small-Size Quantum Dots in Colloidal CdSe Ensembles with Optical Spectroscopy
摘要： It is well-known that optical absorption and photoluminescence (PL) provide information that is sensitive to the size and size distribution of colloidal binary semiconductor quantum dots (QDs). To explore the nature of reaction products, clusters, and/or small-size QDs, we show that it is important to perform as well photoluminescence excitation (PLE) spectroscopy. For two non-hot-injection reactions of cadmium oleate (Cd(OA)2) and selenium (Se) in 1-octadecene (ODE), we show that sequentially extracted products displayed a similar apparent red shift in both absorption and PL with a full width at half-maximum (fwhm) of ～30 nm. We demonstrate that one reaction (with the presence of diphenyl phosphine (HPPh2)) produced multiple types of clusters (with slightly different optical properties) in one ensemble, while the other reaction (without HPPh2) yielded primarily small-size QDs. Our findings provide evidence for the probable existence of clusters within small-size CdSe QD products, the existence of which complicates the size determination of small-size CdSe QDs.
关键词： optical absorption,photoluminescence,photoluminescence excitation spectroscopy,clusters,CdSe quantum dots
更新于2025-09-16 10:30:52