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- V.N. Karazin Kharkiv National University
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Graphene quantum dots enhanced ToF-SIMS for single-cell imaging
摘要： Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has shown promising applications in single-cell analysis owing to its high spatial resolution molecular imaging capability. One of the main drawbacks hindering progress in this field is the relatively low ionization efficiency for biological systems. The complex chemical micro-environment in single cells typically causes severe matrix effects, leading to significant signal suppression of biomolecules. In this work, we investigated the signal enhancement effect of graphene quantum dots (GE QDs) in ToF-SIMS analysis. A × 160 magnification of ToF-SIMS signal for amiodarone casted on glass slide was observed by adding amino-functionalized GE QDs (amino-GE QDs), which was significantly higher than adding previously reported signal enhancement materials and hydroxyl group-functionalized GE QDs (hydroxyl-GE QDs). A possible mechanism for GE QD-induced signal enhancement was proposed. Further, effects of amino-GE QDs and hydroxyl-GE QDs on amiodarone-treated breast cancer cells were compared. A significant signal improvement for lipids and amiodarone was achieved using both types of GE QDs, especially for amino-GE QDs. In addition, ToF-SIMS chemical mapping of single cells with better quality was obtained after signal enhancement. Our strategy for effective ToF-SIMS signal enhancement holds great potential for further investigation of drug metabolism pathways and the interactions between the cell and micro-environment.
关键词： Signal enhancement,Single-cell analysis,Graphene quantum dots,Time-of-flight secondary ion mass spectrometry
更新于2025-11-14 15:32:45
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Ultrathin, Core–Shell Structured SiO <sub/>2</sub> Coated Mn <sup>2+</sup> ‐Doped Perovskite Quantum Dots for Bright White Light‐Emitting Diodes
摘要： All-inorganic semiconductor perovskite quantum dots (QDs) with outstanding optoelectronic properties have already been extensively investigated and implemented in various applications. However, great challenges exist for the fabrication of nanodevices including toxicity, fast anion-exchange reactions, and unsatisfactory stability. Here, the ultrathin, core–shell structured SiO2 coated Mn2+ doped CsPbX3 (X = Br, Cl) QDs are prepared via one facile reverse microemulsion method at room temperature. By incorporation of a multibranched capping ligand of trioctylphosphine oxide, it is found that the breakage of the CsPbMnX3 core QDs contributed from the hydrolysis of silane could be effectively blocked. The thickness of silica shell can be well-controlled within 2 nm, which gives the CsPbMnX3@SiO2 QDs a high quantum yield of 50.5% and improves thermostability and water resistance. Moreover, the mixture of CsPbBr3 QDs with green emission and CsPbMnX3@SiO2 QDs with yellow emission presents no ion exchange effect and provides white light emission. As a result, a white light-emitting diode (LED) is successfully prepared by the combination of a blue on-chip LED device and the above perovskite mixture. The as-prepared white LED displays a high luminous efficiency of 68.4 lm W?1 and a high color-rendering index of Ra = 91, demonstrating their broad future applications in solid-state lighting fields.
关键词： quantum dots,white light-emitting diodes,core–shells,Mn2+-doping,SiO2-coating
更新于2025-11-14 15:32:45
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Increasing photoluminescence quantum yield by nanophotonic design of quantum-confined halide perovskite nanowire arrays
摘要： High photoluminescence quantum yield (PLQY) is required to reach optimal performance in solar cells, lasers and light-emitting diodes (LEDs). Typically, PLQY can be increased by improving the material quality to reduce the non-radiative recombination rate. It is in principle equally effective to improve the optical design by nanostructuring a material to increase light out-coupling efficiency and introduce quantum confinement, both of which can increase the radiative recombination rate. However, increased surface recombination typically minimizes nanostructure gains in PLQY. Here a template guided vapor phase growth of CH3NH3PbI3 (MAPbI3) nanowire (NW) arrays with unprecedented control of NW diameter from the bulk (250 nm) to the quantum confined regime (5.7 nm) is demonstrated, while simultaneously providing a low surface recombination velocity of 18 cm s-1. This enables a 56-fold increase in the internal PLQY, from 0.81 % to 45.1 %, and a 2.3-fold increase in light out-coupling efficiency to increase the external PLQY by a factor of 130, from 0.33 % up to 42.6 %, exclusively using nanophotonic design.
关键词： light out-coupling,photoluminescence quantum yield,quantum confinement,perovskite,photodetector
更新于2025-11-14 15:28:36
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Rapid preparation of homogeneous carbon dots with yellow fluorescence and formation mechanistic investigation
摘要： In this study, homogeneous carbon dots with yellow fluorescence and high absolute fluorescence quantum yields (78.6%) were firstly prepared through a one-step solvothermal method without complicated process of separation, in which sodium citrate, carbamide, and anhydrous calcium chloride were adopted as precursors, while toluene was selected as solvent. The as-prepared carbon dots with an average size of 5.9 nm have a high degree of crystallinity. According to the discussion of the formation mechanism carbon dots, it is found that the toluene guarantee the formation of crystalline core and Ca2+ promotes the formation of carbonaceous core with high crystallinity, which is responsible for the ultrahigh quantum yield. Furthermore, the fluorescent properties of carbon dots are excellent in organic solvents and could be quenched by water, making them a promising material used without any modification in the detection of water in organic solvents, which has a great influence on organic chemical reaction, and may even determine the resultant, yield, and selectivity of organic reaction.
关键词： Detection of water content,Ultrahigh quantum yield,Yellow fluorescence,Carbon dots,Quantum dot
更新于2025-11-14 15:28:36
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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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Solvent-Dependent Sensitization of Ytterbium and Neodymium via an Intramolecular Excimer
摘要： We report the synthesis of a di(1-pyrenyl)-phosphoryl acetophenone ligand containing two pyrenyl moieties linked by a single phosphorus atom. The ligand exhibits solvent-dependent emission: in nonpolar solvents, typical monomeric pyrene emission is observed, whereas in polar solvents, an additional broad and structureless emission appears. The emission in polar solvents is concentration independent and is attributed to the emission of an intramolecular excimer. The coordination of the di(1-pyrenyl)phosphoryl acetophenone ligand as well as the corresponding deprotonated anionic di(1-pyrenyl)phosphoryl acetophenonate ligand was studied with the near-infrared emitting lanthanides, neodymium and ytterbium. Solvent-dependent sensitization of both lanthanides was observed and correlates with the presence of the excimer emission. Sensitization of ytterbium is more efficient than neodymium, and the overall quantum yields were found to be 12.8 and 1.9% for ytterbium and neodymium, respectively.
关键词： solvent-dependent emission,quantum yields,ytterbium,neodymium,intramolecular excimer,lanthanides
更新于2025-11-14 15:24:45
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Screening of quantum-confined Stark effect in nitride laser diodes and superluminescent diodes
摘要： In the present work we report on the observation of carrier-induced screening of built-in electric fields in (Al,In)GaN laser diodes and superluminescent diodes. We use the emission peak energy as a measure of the quantum-confined Stark effect and its screening by free carriers. For superluminescent diodes we observe a steady increase of screening up to the current density of 10 kA/cm2. This shows that the lasing in nitride laser diodes occurs under high electric fields, far from the flat band conditions.
关键词： nitride laser diodes,electric fields,carrier screening,quantum-confined Stark effect,superluminescent diodes
更新于2025-11-14 15:24:45
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Excellent exciton luminescence of CsPbI3 red quantum dots in borate glass
摘要： We have fabricated CsPbI3 perovskite quantum dots in a borate glass by melt-quenching technique. Three representative samples with different treatment conditions are investigated. As treatment condition enhances, energy gap is extracted as 1.75-1.76eV, and photoluminescence peak is adjustable from 675 to 691nm. Full width at half-maximum (FWHM) varies from 43 to 37 nm. PL intensity first increases and then decreases with increasing excitation wavelength, but the peak wavelength and line-shape are independent. High PLQY values of 23.8%-61.4% are obtained. The high PLQY values are attributed to good crystal quality and less energy dissipation. PL lifetime is fitted as 24.0-28.2ns and 100.2-123.0ns for short and long lifetime components in bi-exponential function. For temperature from 25 to 125 oC, PL intensity decreases, but it is reversible. Exciton binding energy is extracted in the level of 375-454meV. The FWHM broadening from 39 to 49nm and peak blue-shift from 690 to 685nm are investigated.
关键词： Photoluminescence quantum yield,Lifetime,CsPbI3,Temperature dependence,Quantum dots glass,Exciton
更新于2025-11-14 15:23:50
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Crystalline Semiconductor Boron Quantum Dots
摘要： Zero-dimensional boron structures have always been the focus of theoretical research owing to its abundant phase structures and special properties. Boron clusters have been reported extensively by combining structure searching theories and photoelectron spectroscopy experiments, however, crystalline boron quantum dots (BQDs) have rarely been reported. Here we report the preparation of large-scale and uniform crystalline semiconductor BQDs from the expanded bulk boron powders via a facile and efficient probe ultrasonic approach in acetonitrile solution. The obtained BQDs have 2.46 nm in an average lateral size and 2.81 nm in thickness. Optical measurements demonstrate that strong quantum confinement effect occurs in the BQDs, implying the increase of the bandgap from 1.80 eV for the corresponding bulk to 2.46 eV for the BQDs. By injecting the BQDs into polyvinylpyrrolidone as an active layer, a BQDs-based memory device is fabricated which shows a rewriteable nonvolatile memory effect with a low transition voltage of down to 0.5 V and a high ON/OFF switching ratio of 103 as well as a good stability.
关键词： ultrasound,quantum dots,nonvolatile memory device,quantum confinement effect,boron
更新于2025-11-14 15:23:50
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Peptide-Functionalized Quantum Dots for Rapid Label-Free Sensing of 2,4,6-Trinitrotoluene
摘要： Explosive compounds, such as 2,4,6-trinitrotoluene (TNT), pose a great concern in terms of both global public security and environmental protection. There are estimated to be hundreds of TNT contaminated sites all over the world, which will affect the health of humans, wildlife, and the ecosystem. Clearly, the ability to detect TNT in soils, water supplies, and wastewater is important for environmental studies but also important for security, such as in ports and boarders. However, conventional spectroscopic detection is not practical for on-site sensing because it requires sophisticated equipment and trained personnel. We report a rapid and simple chemical sensor for TNT by using TNT binding peptides which are conjugated to fluorescent CdTe/CdS quantum dots (QDs). QDs were synthesized in the aqueous phase, and the peptide was attached directly to the surface of the QDs by using thiol groups. The fluorescent emission from the QDs was quenched in response to the addition of TNT. The response could even be observed by the naked eye. The limit of detection from fluorescence spectroscopic measurement was estimated to be approximately 375 nM. In addition to the rapid response (within a few seconds), selective detection was demonstrated. We believe this label-free chemical sensor contributes to progress for the on-site explosive sensing.
关键词： quantum dots (QDs),explosive detection,2,4,6-trinitrotoluene (TNT),label-free sensing,peptide-functionalized
更新于2025-11-14 15:23:50