Yen Hsun Su

Electrostatic studies of π–π interaction for benzene stacking on a graphene layer

Recently, aromatic molecules have been stacked on graphene for applications in biosensors and chemical sensors, although the interaction between them is not well understood. In this paper, we use electrostatic model, double charge rings, and its image charges model to simulate the π–π interaction between benzene and a graphene layer. Furthermore, the results of our model are confirmed by the numerical results from density functional theory and experimental reviews. This model has potential for use in predicting the interactions between aromatic molecules and graphene.

Surface plasmon resonance of gold nano-sea-urchin

The authors synthesized high-quality gold nano-sea-urchin in aqueous solution with an environment-friendly method. They found that the gold nano-sea-urchin can induce the interaction of surface plasmon resonance (SPR) mode with substrate. The SPR peak splits and blueshifts from 630to440nm and the result has potential application for enhanced-Raman scattering, optical communications, and solar cells.

Effects of Rare Earth Metals on Steel Microstructures

Rare earth metals are used in semiconductors, solar cells and catalysts. This review focuses on the background of oxide metallurgy technologies, the chemical and physical properties of rare earth (RE) metals, the background of oxide metallurgy, the functions of RE metals in steelmaking, and the influences of RE metals on steel microstructures. Future prospects for RE metal applications in steelmaking are also presented.

Nanophotonic perovskite solar cell architecture with a three-dimensional TiO2 nanodendrite scaffold for light trapping and electron collection

Nanophotonic perovskite solar cells have been fabricated by infiltrating methylammonium lead iodide (MAPbI3) into the interstices of the quasi-single-crystalline TiO2 nanodendrite (ND) array. The TiO2 ND array in the active layer serves as not only the nanophotonic light trapping structure but also the electron transport medium for enhancing both light harvesting and electron collection to challenge the issue of short electron diffusion length in MAPbI3-based solar cells. Finite difference time domain simulation results indicate that the ND in the MAPbI3 matrix exhibits superior light trapping performance compared to the nanorod (NR), which can well explain the comparable light harvesting in the MAPbI3–TiO2 ND and the MAPbI3–TiO2 NR solar cells although the MAPbI3 amount in the former is ∼10% less. Moreover, the branches developed from the trunks of the NDs will extract the photoelectrons from MAPbI3 to reduce the electron transport length in the MAPbI3 matrix. The higher internal quantum efficiencies, especially at longer wavelengths, confirm the enhanced electron collection in the MAPbI3–TiO2 ND solar cell. Compared to the MAPbI3–TiO2 NR solar cell, the 22% and 25% enhancements in the average Jsc and PCE are respectively attained in the MAPbI3–TiO2 ND solar cells.

Surface plasmon resonance of Au-Cu bimetallic nanoparticles predicted by a quasi-chemical model.

Au-Cu alloys are functional materials with nonlinear optical applications. However, the optical properties of such alloys are difficult to predict due to the random mixing of materials. In this paper, we present a quasi-chemical model to simulate the optical properties of Au-Cu alloy systems based on the mixing of Gibbs free energy. This model is also able to predict the position of the surface plasmon resonance peaks for Au-Cu alloy nanoparticles. The model can be applied to predict the optical properties of alloy systems in the fields of plasmonics and nanophotonics.

Down-conversion photoluminescence sensitizing plasmonic silver nanoparticles on ZnO nanorods to generate hydrogen by water splitting photochemistry

Silver nanoparticles fabricated onto the surface of the ZnO nanorods form the photoanode and generate photoelectric current due to surface plasmon resonance, which serves as anode electrodes in photoelectrochemical hydrogen production. In order to increase the absorption spectrum of photoanode, organic pigments were utilized as photo-sensitizers to generate down-conversion photoluminescence to excite surface plasmon resonances of silver nanoparticles. The way of using light to carry the energy in electronic scattering regime runs the system for the enhancement of solar water splitting efficiency. It was significantly tuned in environmentally sustainable applications for power generation and development of alternative energy.

P3HT-based nanoarchitectural Fano solar cells.

The finite difference time domain simulation shows the existence of an asymmetric quadrupole of Fano resonance on the surface of a gold-silica core-shell (Au@silica) nanoparticle (NP) as being incorporated into the metal oxide nanoarchitecture/P3HT hybrid. Compared to the metal oxide nanoarchitecture/P3HT hybrid solar cell, a 30% enrichment of the short-circuit current density (Jsc) is attained in the P3HT-based nanoarchitectural Fano solar cell with the Au@silica NPs. The enhancement of charge separation in the cell by the electric field of the Fano resonance is directly evidenced by time-resolved photoluminescence measurements. The increase of the degree of P3HT order in the hybrid by the incorporation of Au@silica NPs into the hybrid active layer may also contribute to the enhancement in the Jsc. Charge carrier dynamic measurements show that an electron collection efficiency of ∼97% can be maintained in the P3HT-based nanoarchitectural Fano solar cell. Significant improvement of the efficiency of the inverted metal oxide/P3HT hybrid solar cell is therefore achieved.

Ellipsometric Advances for Local Surface Plasmon Resonance to Determine Chitosan Adsorption on Layer-by-Layer Gold Nanoparticles

The ellipsometric measurement of local surface plasmon resonance (LSPR) caused by the adsorption of chitosan on layer-by-layer gold nanoparticles (Au NPs) was investigated. Six nanometer (6 nm) Au NPs were prepared and layer-by-layer Au NPs were fabricated to shift the LSPR to 520, 540, and 560 nm, respectively, due to the Mie theory. The thicknesses and the fractions of the layer-by-layer Au NPs were measured accurately using a combination of the Fresnel equation and the Maxwell–Garnett equations for ellipsometry. Furthermore, the position of the LSPR was shifted by chitosan. Using trajectory to record the trace of polarized light for ellipsometry resulting from LSPR, it was found that LSPR is predominantly induced when the LSPR position is close to the wavelength of the ellipsometric measurement. The trajectory circle of LSPR is very large for an increase of chitosan adsorption on Au NPs when the LSPR position is close to the detected wavelength. The linear approximation aspect quantifying the trajectory corresponds with the change of LSPR for the adsorption of chitosan, except for cases with low incidence and Brewster angles. The aspects and technologies of ellipsometry will benefit from the findings in this study, with potential applications in the fields of determination of molecular adsorption.

Thermodynamic Calculation among Cerium, Oxygen, and Sulfur in Liquid Iron

Thermodynamic calculation has been applied to predict the inclusion formation in molten SS400 steel. When the Cerium addition in liquid iron is 70 ppm and the initial Oxygen and Sulphur are both 110 ppm, the formation of oxides containing Cerium would experience the transformation from Ce2O3 to CeO2 and also the formation of sulfides containing Cerium would experience the transformation from CeS to Ce2S3 and then to Ce3S4. Below 2000 K the most thermodynamic stable matter is CeO2 and the less thermodynamic stable inclusion is CeS. Only when the amount of [O] is extremely low and the amount of [S] and [Ce] is relatively high, Ce2S3 has the possibility to form.

Ultra-thin titanium nanolayers for plasmon-assisted enhancement of bioluminescence of chloroplast in biological light emitting devices

Ultra-thin titanium films were deposited via ultra-high vacuum ion beam sputter deposition. Since the asymmetric electric field of the metal foil plane matches the B-band absorption of chlorophyll a, the ultra-thin titanium nanolayers were able to generate surface plasmon resonance, thus enhancing the photoluminescence of chlorophyll a. Because the density of the states of plasmon resonance increases, the enhancement of photoluminescence also rises. Due to the biocompatibility and inexpensiveness of titanium, it can be utilized to enhance the bioluminescence of chloroplast in biological light emitting devices, bio-laser, and biophotonics.