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Facile and efficient 3-chlorophenol sensor development based on photolumenescent core-shell CdSe/ZnS quantum dots
摘要： Quantum dots (QDs) are semiconducting inorganic nanoparticles, tiny molecules of 2–10 nm sizes to strength the quantum confinements of electrons. The QDs are good enough to emit light onto electrons for exciting and returning to the ground state. Here, CdSe/ZnS core/shell QDs have been prepared and applied for electrochemical sensor development in this approach. Flat glassy carbon electrode (GCE) was coated with CdSe/ZnS QDs as very thin uniform layer to result of the selective and efficient sensor of 3-CP (3-chlorophenol). The significant analytical parameters were calculated from the calibration plot such as sensitivity (3.6392 μA μM?1 cm?2) and detection limit (26.09 ± 1.30 pM) with CdSe/ZnS/GCE sensor probe by electrochemical approach. The calibration curve was fitted with the regression co-efficient r2 = 0.9906 in the range of 0.1 nM ～ 0.1 mM concentration, which denoted as linear dynamic range (LDR). Besides these, it was performed the reproducibility in short response time and successfully validated the fabricated sensor for 3-CP in the real environmental and extracted samples. It is introduced as a noble route to detect the environmental phenolic contaminants using CdSe/ZnS QDs modified sensor by electrochemical method for the safety of healthcare and environmental fields at broad scales.
关键词： CdSe/ZnS,Quantum dots,electrochemical sensor,3-chlorophenol,environmental safety
更新于2025-09-16 10:30:52
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Strain Effects on the Band Gap and Diameter of CdSe Core and CdSe/ZnS Core/Shell Quantum Dots at Any Temperature
摘要： We present the results of an experimental study about strain effects on the core band gap and diameter of spherical bare CdSe core and CdSe/ZnS core/shell quantum dots (QDs) synthesized by using a colloidal technique at varying temperatures. Structural characterizations were made by using X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) techniques. Optical characterizations were made by using UV-Vis absorption and fluorescence emission spectroscopies. The XRD analysis suggests that the synthesized bare CdSe core and CdSe/ZnS core/shell QDs have zinc blende crystal structure. HRTEM results indicate that the CdSe core and CdSe/ZnS QDs have average particle sizes about 3.50 nm and 4.84 nm, respectively. Furthermore, compressive strain causes an increase (decrease) in the core band gap (diameter) of spherical CdSe/ZnS core/shell QDs at any temperature. An elastic strain-modified effective mass approximation (EMA) predicts that there is a parabolic decrease (increase) in the core band gap (diameter) of QDs with temperature. The diameter of spherical bare CdSe core and CdSe/ZnS core/shell QDs calculated by using the strain-modified EMA, with core band gap extracted from absorption spectra, are in excellent agreement with the HRTEM data.
关键词： diameter,quantum dots,band gap,CdSe,strain effects,CdSe/ZnS,temperature
更新于2025-09-12 10:27:22
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Effect of energy transfer on the optical properties of surface-passivated perovskite films with CdSe/ZnS quantum dots
摘要： Surface passivation is an effective method to protect the surfaces and improve the luminescence properties of perovskite (PS) films. CdSe/ZnS core-shell quantum dots (QDs) have been employed for surface passivation of PS films because of their size-dependent tunable bandgaps. Herein, the energy transfer (ET) behavior of CH3NH3PbI2Br PS films covered with CdSe/ZnS QDs (QD/PS hybrid structures) is characterized by using photoluminescence (PL) and time-resolved PL spectroscopy. The PL decay time and the integrated PL intensity of the QD/PS hybrid structure increase compared with those of the bare PS films, owing to ET from the QDs to the PS and reduced charge traps. The ET efficiency increases from ~7% to 63% for the QD/PS hybrid structure when the core diameter of the QDs decreases from 6.5 to 2.7 nm, respectively. This can be explained by the charge transfer rate enhancement due to the control of energy level alignment of QDs. These results allow us to understand fundamental mechanisms such as ET from QDs to PS films as a function of the size of the QD.
关键词： CdSe/ZnS quantum dots,perovskite films,energy transfer,photoluminescence,surface passivation
更新于2025-09-12 10:27:22
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Metal-enhanced fluorescence of interlaminar composite film with self-assembled quantum Dots/Au@SiO2 microarchitecture
摘要： Quantum dots fluorescence-enhanced films, which mainly consisted of CdSe@ZnS quantum dots and noble metal nanoparticles or nanorods, were formed by layer-by-layer self-assembly techniques. This particular architecture consisting of metal nanoparticles-poly (diallyl dimethylammonium chloride) (PDDA)-QDs was characterized by those fabrication processes mainly including surface-modifying the oleic acid-capped CdSe@ZnS QDs ( high quantum yield of ~89% ) with mercaptopropionic acid (MPA) to be charged negatively (-COO-) for following solution-processed assembly, adjusting the size and coating the gold nanoparticles/nanorods with silica to form suitable dielectric insulation layer and further optimize the fluorescence-enhanced performance, as well as using the cationic polyelectrolyte to control the charges between layers and form opposite charges between two adjacent layers. After optimizing the structure of the quantum dot fluorescence-enhanced films and corresponding surface plasmon enhancement effect, the enhancement factor of 10.8 in Au NPs@SiO2-PDDA-QDs complex film and that of 24.7 in Au NRs@SiO2-PDDA-QDs complex film as compared with the pure quantum dot fluorescence film were achieved, respectively. This indicated that the Au NRs@SiO2-PDDA-QDs complex film was one of the most promising potentials for further display backlight and biometric identifier application.
关键词： CdSe@ZnS quantum dots,Au@SiO2 microarchitecture,electrostatic self-assembly,metal surface plasmon enhancement,Quantum dots fluorescence-enhanced films
更新于2025-09-12 10:27:22
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Photoinduced Modulation of the Emission from СdSe/ZnS Quantum Dots by Photochromic Transformations of Diarylethenes
摘要： A spectral study of the interaction between the molecules of photochromic compounds of the diarylethene class and CdSe/ZnS quantum dots (QDs), in dependence of the structure and nature of functional substituents of photochromes, has been performed. It is shown that both chemical and physical interactions are accompanied by photoinduced modulation of QD emission as a result of photochromic transformations of diarylethenes caused by the inductive transfer of excitation energy from QDs to the diarylethene cyclic isomer.
关键词： diarylethenes,CdSe/ZnS quantum dots,nanomaterials,photoinduced modulation,photochromic transformations,ceramics
更新于2025-09-12 10:27:22
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Development of Ratiometric Fluorescence Sensors Based on CdSe/ZnS Quantum Dots for the Detection of Hydrogen Peroxide
摘要： In this study, carboxyl group functionalized-CdSe/ZnS quantum dots (QDs) and aminofluorescein (AF)-encapsulated polymer particles were synthesized and immobilized to a sol–gel mixture of glycidoxypropyl trimethoxysilane (GPTMS) and aminopropyl trimethoxysilane (APTMS) for the fabrication of a hydrogen peroxide-sensing membrane. CdSe/ZnS QDs were used for the redox reaction of hydrogen peroxide (H2O2) via a reductive pathway by transferring electrons to the acceptor that led to fluorescence quenching of QDs, while AF was used as a reference dye. Herein, the ratiometric fluorescence intensity of CdSe/ZnS QDs and AF was proportional to the concentration of hydrogen peroxide. The fluorescence membrane (i.e., QD–AF membrane) could detect hydrogen peroxide in linear detection ranges from 0.1 to 1.0 mM with a detection limit (LOD) of 0.016 mM and from 1.0 to 10 mM with an LOD of 0.058 mM. The sensitivity of the QD–AF membrane was increased by immobilizing horseradish peroxidase (HRP) over the surface of the QD–AF membrane (i.e., HRP–QD–AF membrane). The HRP–QD–AF membrane had an LOD of 0.011 mM for 0.1–1 mM H2O2 and an LOD of 0.068 mM for 1–10 mM H2O2. It showed higher sensitivity than the QD–AF membrane only, although both membranes had good selectivity. The HRP–QD–AF membrane could be applied to determine the concentration of hydrogen peroxide in wastewater, while the QD–AF membrane could be employed for the detection of α-ketobutyrate.
关键词： ratiometric fluorescence QD membrane,CdSe/ZnS QDs,hydrogen peroxide,α-ketobutyrate,redox reaction
更新于2025-09-12 10:27:22
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Improving the charge balance and performance of CdSe/ZnS quantum-dot light-emitting diodes with a sputtered zinc-tin-oxide electron-transport layer and a thermally evaporated tungsten-oxide charge-restricting layer
摘要： The charge carrier balance and performance of CdSe/ZnS quantum-dot light-emitting diodes (QD-LEDs) with a vacuum-deposited electron-transport layer (ETL) and carrier-restricting layer (CRL) were successfully improved. Optimizing the fabrication process of the reactively sputtered zinc-tin-oxide (ZTO) ETL and adopting a thermally evaporated tungsten-oxide (WOx) CRL improved the electron-hole balance, thus leading to QD-LEDs with improved performance. Impedance spectroscopy analysis was successfully exploited in investigating charge carrier injection into each layer of the QD-LED and electron-hole recombination behaviors. The QD-LED with optimized ZTO ETL and without WOx CRL exhibited 2600 cd m?2 luminance and 3.2 cd A?1 current efficiency, and the QD-LED with both optimized ZTO ETL and a WOx CRL exhibited 3900 cd m?2 luminance and 5.1 cd A?1 current efficiency. These results imply a practical method for improving the electron-hole balance and performance of QD-LEDs, and provide a reliable technique for analyzing the carrier behavior of QD-LEDs.
关键词： CdSe/ZnS quantum-dot,light-emitting diodes,tungsten-oxide,charge balance,zinc-tin-oxide,impedance spectroscopy
更新于2025-09-11 14:15:04
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Photoluminescence Decay of Colloidal Quantum Dots: Reversible Trapping and the Nature of the Relevant Trap States
摘要： Interfaces are crucial factors in shaping the properties of colloidal quantum dots (QDs), in particular the size-dependent optical properties that are a hallmark of these materials. However, the role played by the interfaces associated with QDs on the kinetics of photoluminescence (PL) decay of these nanocrystals is not fully understood even for the most extensively investigated II-VI QDs. In particular, interfaces are a hotbed of trapping sites over which control is essential for efficient performance of QD-based devices, because traps condition PL lifetimes and may be related to PL intermittency. In this work, we analyze the room-temperature PL decay of drop-cast films of CdSe/ZnS QDs varying a number of factors (casting solvent, capping ligands, core/shell interface character). We show how the use of a function that accounts for reversible trapping of photogenerated charge carriers with physically meaningful parameters (time constant, trapping and detrapping rate constants, and average number of traps per QD) can provide valuable information concerning the relevant interfaces, and therefore the nature of the trap states, involved in the recombination of those charge carriers. This approach should be applicable to QDs of a variety of compositions as well as materials beyond inorganic semiconductors.
关键词： photoluminescence decay,trap states,reversible trapping,CdSe/ZnS QDs,colloidal quantum dots
更新于2025-09-11 14:15:04
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Energy Transfer from CdSe/ZnS Nanocrystals to Tetraphenyl Porphyrin
摘要： CdSe/ZnS nanocrystals (NCs) and Tetraphenyl Porphyrin (TPP) are mixed uniformly to prepare CdSe/ZnS NCs/TPP complex. TPP can quench the fluorescent signal of CdSe/ZnS NCs. UV-Vis absorption spectra and fluorescence spectra are employed to analysis the energy transfer. The mechanism of energy transfer is the F?rster resonance energy transfer from CdSe/ZnS to TPP.
关键词： Tetraphenyl Porphyrin,energy transfer,CdSe/ZnS nanocrystals,F?rster resonance energy transfer
更新于2025-09-10 09:29:36