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Oscillator strength and carrier dynamics in type I and inverted type I spherical core/ shell nanostructures under external laser field
摘要： For the first time, the effect of laser on the donor impurity states in spherical nano core/ shell systems is examined theoretically by variation technique. In this work, a step like laser dressed confinement potential is employed to evolve the donor dynamics in two different spherical core/ shell quantum structures namely (a) Type I GaAs/ Al0.3Ga0.7As core shell nanostructure (CSN) and (b) Inverted Type I Al0.3Ga0.7As/ GaAs CSN. Donor binding energy (BE) is calculated for various laser dressing parameter (α0) for various impurity locations (Ri) by varying the dimensions of the systems. Effect of laser on sub-level energy (E0), oscillator strength (P10), transition energy (E10) and the magnitude of dipole matrix element (|M10|) of the systems are also determined. The diverse behavior of type I and inverted type I CSNs are analyzed. It is witnessed that in type I the carrier is highly confined whereas inverted type I favors tunneling. This study will help in understanding the influence of laser field on donor impurity in CSNs and its application towards optical devices.
关键词： Type I core/shell,Laser field,Donor Binding,Oscillator Strength,Inverted Type I core/shell
更新于2025-09-16 10:30:52
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Effect of molarities on structural and optical properties of type-II heterostructure CdS/PbS core/shell quantum dot
摘要： The interrelation between particle sizes and crystal structure in core/shell (CS) semiconductor quantum dots has elicited widespread interest. The effects of precursor concentration of chemically synthesized CdS/PbS CS nanoparticles on structural and optical properties have been reported. CdS/PbS CS QDs shows polycrystalline nature with hexagonal phase in X-ray Diffraction (XRD) pattern, which was also confirmed from SEAD pattern. The particle size was found about 15 nm from the HRTEM images, which was also exhibited CS structure of the NPs. EDX and XRD pattern exhibited the formation of pure CdS/PbS CS structure NPs. The strain in the small spherical NPs is dominant; resulting is shifting of XRD peaks towards higher 2θ values and is found to decrease with an increased crystal size of the core. The effect of molarities on the size of the NPs has seen in the absorption spectra and emission spectra with red shifted. The bandgap of the CS NPs varies inversely with the molar concentration of the nanocrystals. The luminescence intensity exhibited increasing trend with the molar concentration of the nanocrystals. The optical properties were found to be in agreement with the structural properties of the CS NPs.
关键词： Molarities effect,Structural properties,Optical properties,CdS/PbS,Core/shell nanoparticles
更新于2025-09-16 10:30:52
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Plasmonic nonlinearity in GaAs/In <sub/>0.20</sub> Ga <sub/>0.80</sub> As core/shell nanowires
摘要： We have investigated the plasmonic response of GaAs/In0.20Ga0.80As core/shell nanowires driven resonantly by strong THz fields with the amplitude of few MV/cm. The plasmon mode exhibits a systematic redshift with the suppression of the spectral weight with the increase of the driving THz field. Interestingly, the scaling of the plasmon parameters does not follow the usual quadratic behavior, indicating inhomogeneous intervalley electron scattering across the nanowire.
关键词： THz fields,intervalley electron scattering,GaAs/In0.20Ga0.80As,Plasmonic nonlinearity,core/shell nanowires
更新于2025-09-16 10:30:52
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From normal diffusion to superdiffusion: Photothermal heating of plasmonic core-shell microgels
摘要： The motion of core-shell colloids during laser heating is studied using angle-dependent pump-probe dynamic light scattering. The cores consist of a single spherical gold nanoparticle whose localized surface plasmon resonance has a strong spectral overlap with the wavelength of the pump laser. They are homogeneously encapsulated in thick hydrogel shells composed of either chemically cross-linked poly-N-isopropylacrylamide or poly[2-(2-methoxyethoxy)ethyl methacrylate], both of which exhibit a temperature-dependent volume phase transition. Thus, upon heating beyond the transition temperature, the hydrogel shells shrink. Intensity-time autocorrelation functions are recorded while illuminating the samples with the pump laser and hence heating the gold cores. With increasing laser intensity, the dynamics changes from normal Brownian motion to superdiffusion. Nevertheless, in the high-q limit, the relaxation times can be extracted and used to estimate the temperature increase, which can reach almost 10 K. This causes a significant deswelling of the hydrogel shells, which is also measured.
关键词： temperature-dependent volume phase transition,photothermal heating,dynamic light scattering,superdiffusion,plasmonic core-shell microgels
更新于2025-09-16 10:30:52
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SiNW/C@Pt Arrays for High-Efficiency Counter Electrodes in Dye-Sensitized Solar Cells
摘要： Modern energy needs and the pressing issue of environmental sustainability have driven many research groups to focus on energy-generation devices made from novel nanomaterials. We have prepared platinum nanoparticle-decorated silicon nanowire/carbon core–shell nanomaterials (SiNW/C@Pt). The processing steps are relatively simple, including wet chemical etching to form the silicon nanowires (SiNWs), chemical vapor deposition to form the carbon shell, and drop-casting and thermal treatment to embed platinum nanoparticles (Pt NPs). This nanomaterial was then tested as the counter electrode (CE) in dye-sensitized solar cells (DSSCs). SiNW/C@Pt shows potential as a good electrocatalyst based on material characterization data from Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Raman spectroscopy shows that the surface reactivity of the SiNW/C is increased by the decoration of Pt NPs. These data also show that the carbon shell included both graphitic (sp2 hybridization) and defective (sp3 hybridization) phases of carbon. We achieved the minimum charge-transfer resistance of 0.025 ? · cm2 and the maximum ef?ciency of 9.46% with a symmetric dummy cell and DSSC device fabricated from the SiNW/C@Pt CEs, respectively.
关键词： core–shell,defective carbon,electrocatalytic activity,dye-sensitized solar cells (DSSCs),counter electrodes (CEs),silicon nanowires (SiNWs)
更新于2025-09-16 10:30:52
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Core-shell nanocomposite of superparamagnetic Fe3O4 nanoparticles with poly(m-aminobenzenesulfonic acid) for polymer solar cells
摘要： Superparamagnetic Fe3O4 nanoparticles play a significant role in enhancing the performance and efficiency of polymer-based solar cells using nanocomposites. For the first time in this study, a novel superparamagnetic core-shell nanocomposite of poly(m-aminobenzenesulfonic acid) (PABS) and Fe3O4 was synthesized by in-situ polymerization of m-ABS as a monomer in the presence of FeCl3.6H2O as oxidant under solid-state conditions. The poly(m-aminobenzenesulfonic acid) (PABS)-Fe3O4 nanocomposite (NCPABS-Fe3O4) was characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) that revealed a core-shell morphology. Under simulated solar irradiation, the photovoltaic cell characteristics were measured. Based on our results, the polymer-hybrid solar cell was fabricated using FTO/TiO2/NCPABS-Fe3O4/Al and demonstrated a power conversion efficiency (PCE or η) 4.24% that was approximately 660% higher than those obtained from FTO/TiO2/(PABS)/Al. We have also proposed a new mechanism for the 660% enhanced efficiency. To the best of our knowledge, this is the highest enhancement reported in the literature. Our results showed that the polymer-hybrid solar cell was completely efficient with a high η in comparison with similar ones reported in literature, and also had less fabrication costs using green synthesis conditions with a simple structure and displayed resistance to oxidation with high stability.
关键词： conductive polymers,Fe3O4 nanoparticles,Solar cell,photovoltaics,core-shell nanocomposite
更新于2025-09-16 10:30:52
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Vis–IR wide-spectrum photodetector at room temperature based on p-n junction-type GaAs1-xSbx/InAs core-shell nanowire
摘要： Infrared (IR) detection at room temperature is very important in many fields. Nanoscale wide-spectrum photodetectors covering IR range are still rare, although they are desired in many applications, such as in integrated optoelectronic devices. Here, we report a new kind of photodetector based on p?n heterojunction-type GaAs1-xSbx/InAs core-shell nanowires. The photodetectors demonstrate high response to the lights ranging from visible light (488 nm) to short-wavelength IR (1800 nm) at room temperature under a very low bias voltage of 0.3 V. The high performances of the devices include an ultralow dark current (32 pA at room temperature), a fast response speed (0.45 ms) to 633 nm light, high responsivity to 1310 nm telecommunication light (0.12 A/W), and high response even to 1800 nm light (on/off ratio of 2.5), etc. Besides, the devices also show excellent rectifying I-V characteristics (the current rectification ratio being ~178 in a voltage range of ± 0.3 V). These results suggest that the GaAs1-xSbx/InAs core-shell nanowires devices are promising for applications in nanoelectronic devices, optoelectronic devices and integrated optoelectronic devices.
关键词： P-N junction,IR,III-V nanowires,core-shell nanowires,Photodetector
更新于2025-09-16 10:30:52
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TiN-contained polymer-metal core-shell structured nanocone array: Engineering of sensor performance by controlling plasmonic properties
摘要： Metal nanostructures have great potential for optical label-free biosensors based on localized surface plasmon resonance (LSPR). The sensitivity of a metal nanostructure-based label-free biosensor (i.e., plasmonic sensor) depends on its plasmonic properties, which su?er a decrease in sensitivity by energy losses in the metal material. Here, we demonstrate an approach to improve the plasmonic properties of metal nanostructures by controlling the carrier density in the base polymer material using titanium nitride (TiN). It is expected that the light energy absorbed by TiN is converted into excitons, and it will assist LSPs in the metal nanostructure; thus, the losses of the metal material are compensated by the excitons excited in TiN. We designed a TiN-contained polymer-metal core-shell structured nanocone array (NCA), comprising TiN nanoparticles (NPs) in a polymer core and metal shell (Au or Ag), and realized improvement of the refractive index (RI) sensitivity of a label-free biosensor by optimizing the TiN-contained polymer composition. As a result, the TiN-contained polymer-metal NCA, with a TiN NP concentration of 10 wt% in the polymer core, had a 1.5-fold higher RI sensitivity than that of the same NCA without TiN NPs. The results of the resistance measurement of the metal surface with the TiN NP-contained polymer (10 wt%) under light exposure suggest the conversion of exposed light into LSPs of metal via TiN. It is suggested that plasmonic properties and sensor performances can be improved by the presented approach. Moreover, in DNA hybridization detection, an extremely low limit of detection of 117.5 fM was achieved.
关键词： Localized surface plasmon resonance (LSPR),Core-shell nanostructure,DNA detection,Carrier engineering,Biosensor,Titanium nitride
更新于2025-09-16 10:30:52
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Multiplexed surface plasmon imaging of serum biomolecules: Fe3O4@Au Core/shell nanoparticles with plasmonic simulation insights
摘要： Nano-biosensors that are not only sensitive and selective, but also enable multiplex detection of ultra-low levels of both large and small biomolecules in clinical sample matrices are essential for in vitro diagnostics. We present herein a multiplex surface plasmon microarray design that employs citrate-stabilized Fe3O4@Au core/shell nanoparticles (NPs) as the plasmon signal ampli?cation label for combined detection of serum proteins and nucleotide markers. The multiplex sensing is demonstrated using two interleukins (IL-6 and IL-8) and two microRNAs (miRNA-21 and miRNA-155) in 10% serum, which is clinically relevant than simple bu?er solution based biosensors. We observed that the surface plasmon signal change for larger proteins even at higher concentrations was less than the relatively smaller miRNA molecules. We draw two conclusions from this result: (i) the number of selectively bound analytes onto the sensor (i.e., antigen for an antibody or miRNA for a capture nucleotide) in?uences the signal change, and (ii) the extent of interaction of the detection probe carrying core/shell NP labels with the sensor surface plasmons in?uences the amount of signal change. Results indicate that both factors, (i) and (ii), are greater for small oligonucleotide hybridization assembly than a large sandwich protein immunoassembly. The core/shell NPs o?ered several fold enhanced sensitivity and wider dynamic range of detection over assays without using them. With recently growing attention on in vitro diagnostics for painless/minimally-invasive detection of diseases and abnormalities, ?ndings presented herein are important for designing novel multiplex biosensors for real sample analysis in complex matrices.
关键词： serum proteins,wide dynamic range,serum miRNAs,Multiplex imaging,core/shell nanoparticles,FDTD simulation
更新于2025-09-16 10:30:52
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Application of Core–Shell Metallic Nanoparticles in Hybridized Perovskite Solar Cell—Various Channels of Plasmon Photovoltaic Effect
摘要： We analyze the microscopic mechanism of the improvement of solar cell efficiency by plasmons in metallic components embedded in active optical medium of a cell. We focus on the explanation of the observed new channel of plasmon photovoltaic effect related to the influence of plasmons onto the internal cell electricity beyond the previously known plasmon mediated absorption of photons. The model situation we analyze is the hybrid chemical perovskite solar cell CH3NH3PbI3?αClα with inclusion of core–shell Au/Si02 nanoparticles filling pores in the Al2O3 or TiO2 porous bases at the bottom of perovskite layer, application of which improved the cell efficiency from 10.7 to 11.4% and from 8.4 to 9.5%, respectively, as demonstrated experimentally, mostly due to the reduction by plasmons of the exciton binding energy.
关键词： plasmons,perovskite solar cells,plasmon photo-effect,core–shell nanoparticles,metallized cells
更新于2025-09-16 10:30:52