- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Size-controlled synthesis of gold nanoparticles by ultrafine bubbles and pulsed ultrasound
摘要： Size-controlled gold nanoparticles (AuNPs) were synthesized by ultrasonic irradiation of HAuCl4 aqueous solutions with the aid of ultrafine bubbles (UFBs) in the absence of any capping and reducing agents. Upon addition of air-UFBs, the mean diameter of the spherical AuNPs decreased. This result was attributed to the sonochemical reduction of gold ions in aqueous solution being accelerated by the UFBs. Moreover, the AuNPs were stable in a solution containing UFBs because AuNPs electrostatically adsorbed onto UFBs, whose lifetime in water was very long. Compared with the mean diameter of AuNPs synthesized with argon-, nitrogen- and oxygen-UFBs, that of AuNPs synthesized with air-UFBs was smaller. Pulsed ultrasound delivered with the same time-averaged power as continuous-wave irradiation further decreased the mean diameter of the AuNPs. Size-controlled synthesis of AuNPs without the use of a capping or reducing agent was successful through optimization of the number air-UFBs and the pulsed ultrasound conditions.
关键词： Gold nanoparticles,Size control,Ultrasound,Pulse wave,Ultrafine bubbles,Colloidal stabilization
更新于2025-09-19 17:13:59
-
Environmentally friendly Mn-alloyed core/shell quantum dots for high-efficiency photoelectrochemical cells
摘要： Colloidal quantum dots (QDs)-based photoelectrochemical (PEC) cells are cost-effective devices showing remarkable solar-to-fuel conversion efficiency. However, the extensive use of highly toxic elements (e.g. Pb and Cd) in QD’s synthesis and device fabrication is still a major challenge towards their practical development. Herein, we fabricate a solar-driven PEC cell based on environment-friendly Mn-alloyed CuInS2 (MnCIS)/ZnS core/shell QDs, showing more favorable band alignment, efficient charge transfer, reduced charge recombination as well as lower charge transfer resistance with respect to the control device fabricated using unalloyed CuInS2 (CIS)/ZnS core/shell QDs. An unprecedented photocurrent density of ~5.7 mA/cm2 with excellent stability was obtained in as-fabricated MnCIS/ZnS core/shell QDs-based PEC device when operated under standard one solar irradiation (AM 1.5G, 100 mW/cm2). These results indicate that the transition metal-alloyed environment-friendly core/shell QDs are promising for next-generation solar technologies.
关键词： Colloidal quantum dots,Photoelectrochemical cells,Mn-alloyed CuInS2,ZnS core/shell,Solar-to-fuel conversion
更新于2025-09-19 17:13:59
-
Optical nanogap antennas as plasmonic biosensors for the detection of miRNA biomarkers
摘要： Nanoplasmonic biosensors based on nanogap antennas structures usually demand complex and expensive fabrication processes in order to achieve a good performance and sensitive detection. We here report the fabrication of large-area nanoplasmonic sensor chips based on nanogap antennas by employing a customized, simple and low-cost colloidal lithography process. By precisely controlling the angle for tilted e-beam metal evaporation, an elliptical mask is produced, which defines the total length of the dipole antenna nanostructures while assuring that the plasmonic response is oriented in the same direction along the sensor chip. Large-area sensor chips of nanogap antennas formed by pairs of gold nanodisks separated by gaps with an average size of 11.6 ± 4.7 nm are obtained. The optical characterization of the nanogap antenna structures in an attenuated total reflection (ATR) configuration shows a bulk refractive index sensitivity of 422 nm/RIU, which is in agreement with FDTD numerical simulations. The biosensing potential of the cm2-sized nanostructured plasmonic sensor chips has been evaluated for the detection of miRNA-210, a relevant biomarker for lung cancer diagnosis, through a DNA/miRNA hybridization assay. A limit of detection (LOD) of 0.78?nM (5.1 ng mL-1) was achieved with no need of further amplification steps, demonstrating the high sensitivity of these plasmonic nanogap antennas for the direct and label-free detection of low molecular weight biomolecules as miRNAs.
关键词： nanoplasmonic biosensors,miRNA biomarkers,colloidal lithography,nanogap antennas,lung cancer diagnosis
更新于2025-09-19 17:13:59
-
Ag2ZnSnS4 Nanocrystals Expand the Availability of RoHS Compliant Colloidal Quantum Dots
摘要： The demonstration of the quantum confinement effect in colloidal quantum dots (QDs) has been extensively studied and exploited mainly in Pb and Cd chalcogenide systems. There has been an urgent need recently for the development of non(less)-toxic colloidal QDs to warrant compliance with current safety regulations (Restriction of Hazardous Substances (RoHS) Directive 2002/95/EC). Herein, we report Pb/Cd-free, solution processed luminescent Ag2ZnSnS4 (AZTS) colloidal QDs. We present a selective and controlled amine and thiol-free synthesis of air stable luminescent Ag2ZnSnS4 QDs by hot injection technique. By controlling the reaction conditions we obtain controlled size variation, and demonstrate the quantum confinement effect that is in good agreement with the theoretically calculated values. The bandgap of the AZTS QDs is size-tunable in the near infrared from 740 nm to 850 nm. Finally, we passivate the surface with Zn-oleate, which yields higher quantum yield (QY), longer lifetime and better colloidal stability.
关键词： near infrared,RoHS compliant,Ag2ZnSnS4,colloidal quantum dots,quantum confinement,Zn-oleate passivation
更新于2025-09-19 17:13:59
-
<i>(Invited)</i> Mid-Infrared Colloidal Quantum Dot Based Nanoelectronics and Nano-Optoelectronics
摘要： Electronic and optoelectronic devices fabricated from colloidal quantum dots (CQDs) provide a promising path toward realizing low-cost devices with greatly simplified device fabrication procedure, owing to their solution-processability. The impact that CQD technology would bring is expected to be significant, especially in the mid-infrared application areas, which is currently dominated by epitaxial semiconductor technologies. In this work, we introduce a new generation of infrared CQDs, namely Ag2Se CQDs, which has been recently uncovered to show distinct optical absorption in the mid-infrared. We report on the fabrication of solution-processed photoconductive photodetectors and discuss our analyses on the electronic and optoelectronic characteristics of our devices. We also demonstrate the feasibility of mid-infrared photodetection with a measured peak responsivity of 0.16 mA/W at 4 μm under room temperature operation.
关键词： Ag2Se,solution-processability,photodetectors,mid-infrared,colloidal quantum dots
更新于2025-09-19 17:13:59
-
23.4: <i>Invited Paper:</i> The Longevity Study for Hybrid Colloidal Quantum Dot Optoelectronic Devices
摘要： The nano-scale size of colloidal quantum dots provide unique properties, such as strong luminescent efficiency, wavelength tunable emission, and narrow linewidth etc., which are desirable for high quality display devices. However, the reliability of these nanoparticles is always the center of attention when the commercialization issue is discussed. In this paper, we will review our latest result on the hybrid package method that can dramatically these magnificent optoelectronic materials . lifetime of improve the
关键词： reliability tests,Light emitting diodes,colloidal quantum dots,solar cells
更新于2025-09-19 17:13:59
-
Dynamic Ligand Surface Chemistry of Excited PbS Quantum Dots
摘要： The ligand shell around colloidal quantum dots mediates the electron and energy transfer processes that underpin their use in optoelectronic and photocatalytic applications. Here, we show that the surface chemistry of carboxylate anchoring groups of oleate ligands passivating PbS quantum dots undergoes significant changes when the quantum dots are excited to their excitonic states. We directly probe the changes of surface chemistry using time-resolved mid-infrared spectroscopy that records the evolution of the vibrational frequencies of carboxylate groups following excitation of the electronic states. The data reveal a reduction of the Pb?O coordination of carboxylate anchoring groups to lead atoms at the quantum dot surfaces. The dynamic surface chemistry of the ligands may increase their surface mobility in the excited state and enhance the ability of molecular species to penetrate the ligand shell to undergo energy and charge transfer processes that depend sensitively on distance.
关键词： surface chemistry,PbS quantum dots,ligand shell,colloidal quantum dots,time-resolved mid-infrared spectroscopy
更新于2025-09-19 17:13:59
-
Position Dependence of Emission Wavelength of a SiO2 Colloidal Photonic-Crystal Laser
摘要： In this paper, a wavelength tunable colloidal-crystal laser with monodispersed silica particles was demonstrated. Silica particles were synthesized through the modified St?ber process and self-assembled into the colloidal photonic-crystal structure, which was then used to form the optic cavity of a wavelength tunable laser device. Due to Bragg’s diffraction of the colloidal photonic-crystal and the coffee ring effect, the forbidden energy gap of light varied with different lattice sizes at different positions of the colloidal photonic-crystal. When the pumping pulsed laser irradiated on the gain medium of the sample, the fluorescence was restricted and enhanced by the colloidal photonic-crystal. Lasing emission with a single peak occurred when the energy of the pumping laser exceeded the threshold energy. The threshold energy and the full-width at half-maximum (FWHM) of the proposed laser were 7.63 μJ/pulse and 2.88 nm, respectively. Moreover, the lasing wavelength of the colloidal photonic-crystal laser could be tuned from 604 nm to 594 nm, corresponding to the various positions in the sample due to the coffee ring effect.
关键词： St?ber process,colloidal-crystal laser,wavelength tunable,self-assemble,silica particles
更新于2025-09-19 17:13:59
-
Colloidal Assembly of Aua??Quantum Dota??Au Sandwiched Nanostructures with Strong Plasmona??Exciton Coupling
摘要： Strong plasmon-exciton coupling could occur in hybrid metal-dye/semiconductor nanostructures, where the fast energy exchange between plasmons and excitons leads to two new eigenmodes of the system, known as Rabi splitting. In experiment, strongly coupled nanosystems are difficult to obtain because they require some strict conditions, such as low plasmonic damping, small plasmon mode volume, and good spectral overlap. This work demonstrates strongly coupled metal-semiconductor nanostructures can be constructed using colloidal assembly. Specifically, sandwiched Au-QD-Au nanostructures were created through the assembly of Au nanoparticles and colloidal quantum dots (QDs). The sizes of the QDs and the assembly conditions were varied to control the mode volume of the plasmonic cavity formed between the two Au nanoparticles. With decreased gap size, Rabi splitting was observed in both dark-field scattering and fluorescence spectra of single Au-QD-Au nanostructures. Theoretical simulations revealed that the strong coupling occurred between the excitons and the octupolar plasmon modes.
关键词： Au-QD-Au nanostructures,Rabi splitting,octupolar plasmon modes,plasmon-exciton coupling,colloidal assembly
更新于2025-09-19 17:13:59
-
Quantum Dot-Plasmon Lasing with Controlled Polarization Patterns
摘要： The tailored spatial polarization of coherent light beams is important for applications ranging from microscopy to biophysics to quantum optics. Miniaturized light sources are needed for integrated, on-chip photonic devices with desired vector beams; however, this issue is unresolved because most lasers rely on bulky optical elements to achieve such polarization control. Here, we report on quantum dot-plasmon lasers with engineered polarization patterns controllable by near-field coupling of colloidal quantum dots to metal nanoparticles. Conformal coating of CdSe?CdS core?shell quantum dot films on Ag nanoparticle lattices enables the formation of hybrid waveguide-surface lattice resonance (W-SLR) modes. The sidebands of these hybrid modes at nonzero wavevectors facilitate directional lasing emission with either radial or azimuthal polarization depending on the thickness of the quantum dot film.
关键词： nanolaser,band structure engineering,radially and azimuthally polarization states,surface lattice resonances,colloidal quantum dots,lattice plasmons,waveguide
更新于2025-09-19 17:13:59