Formation, Optical Properties and Applications of Edge Gold-Coated Silver Nanoprisms

2015 ◽  
Vol 1737 ◽  
Author(s):  
Mohammad M. Shahjamali ◽  
Michael Salvador ◽  
Negin Zaraee

ABSTRACTA facile, high-yield synthesis of edge gold-coated silver nanoprisms (GSNPs) with a gold nanoframe as thin as 1.7 nm and their comprehensive characterizations by using various spectroscopic and microscopic techniques is introduced. The GSNPs exhibit remarkably higher stability than silver nanoprisms (SNPs) and are therefore explored as effective optical antennae for light-harvesting applications. When embedded into a bulk heterojunctions film of P3HT:PCBM, plasmonic GSNPs with a localized surface plasmon resonance (LSPR) around 500 nm can effectively act as optical antennae to enhance light harvesting in the active layer. As a result, we measured up to 7-fold enhancement in the polaron generation yield through photoinduced absorption spectroscopy. Owing to the high stability and strong field enhancement, the presented GSNPs feature great potential as plasmonic probes for photovoltaic applications and LSPR sensing.

Instruments ◽  
2019 ◽  
Vol 3 (4) ◽  
pp. 59
Author(s):  
Joshua Mann ◽  
Gerard Lawler ◽  
James Rosenzweig

Electron rescattering has been well studied and simulated for cases with ponderomotive energies of the quasi-free electrons, derived from laser–gas and laser–surface interactions, lower than 50 eV. However, with advents in longer wavelengths and laser field enhancement metallic surfaces, previous simulations no longer suffice to describe more recent strong field and high yield experiments. We present a brief introduction to and some of the theoretical and empirical background of electron rescattering emissions from a metal. We set upon using the Jellium potential with a shielded atomic surface potential to model the metal. We then explore how the electron energy spectra are obtained in the quantum simulation, which is performed using a custom computationally intensive time-dependent Schrödinger equation solver via the Crank–Nicolson method. Finally, we discuss the results of the simulation and examine the effects of the incident laser’s wavelength, peak electric field strength, and field penetration on electron spectra and yields. Future simulations will investigate a more accurate density functional theory metallic model with a system of several non-interacting electrons. Eventually, we will move to a full time-dependent density functional theory approach.


Author(s):  
Mohammad Tariq Yaseen

Metal nanoparticles are very important for their optical properties when they interact with light. Metal nanoparticles have the ability to confine the collective oscillation of electrons, which is called localized surface plasmon resonance (LSPR). In this work, silver nanoparticles have been proposed to enhance light harvesting, which could be useful for different applications. Metal nanoparticles such as gold and silver nanoparticles have the ability to concentrate field in a very small space. In this study, gold and silver nanoparticles optical response was investigated using frequency domain simulation. The resonance wavelength of gold and silver nanoparticles was about 550 nm and 400 nm, respectively. Silver nanoparticles showed better LSPR performance than gold nanoparticles. Therefore, silver nanoparticles were chosen for optical field enhancement. Here silver nanoparticles were placed on a silicon substrate for optical field enhancement. To study the effect of size on the optical response of silver nanoparticles, the optical properties of this structure with different silver nanoparticles diameter values were investigated. Silver nanoparticles with 40 nm diameters showed a better optical response. To study the effect of the distance between silver nanoparticles on the optical response, different gap values were put between silver nanoparticles. The gap value of 4 nm showed a better optical response. The obtained results showed that the localized field is strongly dependent on the metal type, size, and space between nanoparticles. In addition, the optical field concentration can be controlled by tuning the size and space between silver nanoparticles. This will support localized field enhancement. The enhanced localized field will increase the field absorption near the surface, which can be beneficial for energy harvesting applications such as solar cells and detectors


Nanophotonics ◽  
2017 ◽  
Vol 7 (2) ◽  
pp. 371-391 ◽  
Author(s):  
Yan-Gang Bi ◽  
Jing Feng ◽  
Jin-Hai Ji ◽  
Fang-Shun Yi ◽  
Yun-Fei Li ◽  
...  

AbstractLightweight and low-cost organic photovoltaics (OPVs) hold great promise as renewable energy sources. The most critical challenge in developing high-performance OPVs is the incomplete photon absorption due to the low diffusion length of the carrier in organic semiconductors. To date, various attempts have been carried out to improve light absorption in thin photoactive layer based on optical engineering strategies. Nanostructure-induced light harvesting in OPVs offers an attractive solution to realize high-performance OPVs, via the effects of antireflection, plasmonic scattering, surface plasmon polarization, localized surface plasmon resonance and optical cavity. In this review article, we summarize recent advances in nanostructure-induced light harvesting in OPVs and discuss various light-trapping strategies by incorporating nanostructures in OPVs and the fabrication processing of the micro-patterns with high resolution, large area, high yield and low cost.


2020 ◽  
Vol 10 (6) ◽  
pp. 840-848
Author(s):  
Jyoti Katyal

Objective: The localized surface plasmon resonance (LSPR) and field enhancement of multilayered nanostructure over single and dimer configuration is studied using finite difference time domain (FDTD) method. Experimental: In multilayered nanostructure, there exist concentric nanoshells and metallic core which are separated by a dielectric layer. Strong couplings between the core and nanoshell plasmon resonance modes show a shift in LSPR and enhancement in field around nanostructure. The calculation of the electric field enhancement shows a sharp increase in the electric field on the surface of inner core i.e., inside the dielectric layer of Metal-Dielectric-Metal (MDM) structure whereas smaller enhancement on the outer layer of MDM structure is observed. Results: The Au-Air-Au mono MDM nanostructure shows strong near-field enhancement as compared to bare nanosphere in the infrared region, which have potential applications in surfaceenhanced spectroscopy, whereas Al-Air-Al and Ag-Air-Ag shows potential towards lower wavelength region. On coupling the MDM nanostructure forming a dimer configuration the field enhancement factor increases to 10^8. Conclusion: As compared to other nanostructures, MDM nanostructure provides both strong field enhancement and wide wavelength tunability therefore promising for surface enhanced Raman spectroscopy (SERS) applications.


Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2579 ◽  
Author(s):  
Varun Vohra

Natural photosynthetic systems contain several dyes such as carotenoids or chlorophylls which are adequately arranged to produce efficient photoinduced charge separation and electron transfer. Several research groups have attempted integrating these natural dyes and photosynthetic systems into functional organic solar cells (OSCs) producing power conversion efficiencies (PCEs) up to 0.99%. The studies presented in this short review emphasize that functionalization of natural dyes can considerably improve their PCEs. For instance, chlorophyll derivatives can yield PCEs up to 2.1%, and copolymers produced with isoindigo as an electron-deficient unit generate high PCEs up to 8%, respectively, when combined with fullerene C70 based electron acceptors in the OSC active layers. An alternative approach for natural dye integration into OSC architectures is to place these light-harvesting antennas at the interface between the active layer and the charge collection layers in these low-cost photovoltaic devices. This strategy produces large PCE increases up to 35% with respect to OSCs prepared without the interlayer. When light-harvesting systems are combined with silver nanoprisms as interlayers, additional localized surface plasmon resonance effects result in high-performance OSCs that integrate natural photosynthetic systems and demonstrate a PCE over the milestone value of 10%.


2020 ◽  
Vol 12 ◽  
Author(s):  
Jyoti Katyal ◽  
Shivani Gautam

Background: A relatively narrow LSPR peak and a strong inter band transition ranging around 800 nm makes Al strongly plasmonic active material. Usually, Al nanoparticles are preferred for UV-plasmonic as the SPR of small size Al nanoparticles locates in deep UV-UV region of the optical spectrum. This paper focused on tuning the LSPR of Al nanostructure towards infrared region by coating Au layer. The proposed structure has Au as outer layer which prevent the further oxidation of Al nanostructure. Methods: The Finite Difference Time Domain (FDTD) and Plasmon Hybridization Theory has been used to evaluated the LSPR and field enhancement of single and dimer Al-Al2O3-Au MDM nanostructure. Results: It is observed that the resonance mode show dependence on the thickness of Al2O3 layer and also on the composition of nanostructure. The Au layered MDM nanostructure shows two peak of equal intensities simultaneously in UV and visible region tuned to NIR region. The extinction spectra and electric field distribution profiles of dimer nanoparticles are compared with monomer to reveal the extent of coupling. The dimer configuration shows higher field enhancement ~107 at 1049 nm. By optimizing the thickness of dielectric layer the MDM nanostructure can be used over UV-visible-NIR region. Conclusion: The LSPR peak shows dependence on the thickness of dielectric layer and also on the composition of nanostructure. It has been observed that optimization of size and thickness of dielectric layer can provide two peaks of equal intensities in UV and Visible region which is advantageous for many applications. The electric field distribution profiles of dimer MDM nanostructure enhanced the field by ~107 in visible and NIR region shows its potential towards SERS substrate. The results of this study will provide valuable information for the optimization of LSPR of Al-Al2O3-Au MDM nanostructure to have high field enhancement.


2021 ◽  
Author(s):  
Hai Liu ◽  
Benlei Zhao ◽  
Xu Zhang ◽  
Hancheng Zhang ◽  
Bo Wu ◽  
...  

AbstractA high-sensitive numerical measurement of methane based on the combined use of the localized surface plasmon resonance (LSPR) and Fano resonance in a slotted metal-dielectric-metal (MDM) periodic structure is numerically investigated. A groove is etched in an original MDM structure to excite the diploe mode at both sides of the groove, and the coherent coupling of two dipole modes is enhanced to realize a fast response, which is beneficial to gas-sensing. The influence of geometric parameters on the reflection spectra and methane sensitivity are analyzed to obtain optimal geometry. Moreover, an etching ring is introduced on the top metal to further raise the coupling area and coupling strength. The Fano resonance is subtly integrated into the optimized structure with asymmetry to achieve greater gas sensitivity. After the introduction of the Fano resonance, the field enhancement caused by the LSPR effect becomes greater and the methane sensitivity can reach up to 8.421 nm/% in numerical calculations, which increases 56.8% more than that of the original one. The combined use of the LSPR and Fano resonance in an optimized MDM structure provides an effective method for high-sensitive gas detection.


Nanophotonics ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 435-451 ◽  
Author(s):  
Taehee Kang ◽  
Young-Mi Bahk ◽  
Dai-Sik Kim

AbstractThrough the manipulation of metallic structures, light–matter interaction can enter into the realm of quantum mechanics. For example, intense terahertz pulses illuminating a metallic nanotip can promote terahertz field–driven electron tunneling to generate enormous electron emission currents in a subpicosecond time scale. By decreasing the dimension of the metallic structures down to the nanoscale and angstrom scale, one can obtain a strong field enhancement of the incoming terahertz field to achieve atomic field strength of the order of V/nm, driving electrons in the metal into tunneling regime by overcoming the potential barrier. Therefore, designing and optimizing the metal structure for high field enhancement are an essential step for studying the quantum phenomena with terahertz light. In this review, we present several types of metallic structures that can enhance the coupling of incoming terahertz pulses with the metals, leading to a strong modification of the potential barriers by the terahertz electric fields. Extreme nonlinear responses are expected, providing opportunities for the terahertz light for the strong light–matter interaction. Starting from a brief review about the terahertz field enhancement on the metallic structures, a few examples including metallic tips, dipole antenna, and metal nanogaps are introduced for boosting the quantum phenomena. The emerging techniques to control the electron tunneling driven by the terahertz pulse have a direct impact on the ultrafast science and on the realization of next-generation quantum devices.


2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Feng Shan ◽  
Tong Zhang ◽  
Sheng-Qing Zhu

The effects of corner shape of silver (Ag) nanocubes (NCs) on optical absorptions of organic solar cells (OSCs) are theoretically investigated by finite element method (FEM) calculations. The absorption of sun light in the active layer is calculated. Significant absorption enhancements have been demonstrated in metallic region with different shapes of Ag NCs, among them corner radius (R) is zero result in the best light absorption performance of up to 55% enhancement with respect to bare OSCs. The origins of increased absorption are believed to be the effects of the huge electric field enhancement and increased scattering upon the excitation of localized surface plasmon resonance (LSPR). Apart from usingR=0, we show thatR=3, 6, and 11.29 of Ag NCs in metallic region of active layer may also result in the maximum comparable absorption enhancement of 49%, 41%, and 28%, respectively. In addition, a significant effect of the period of NCs is observed.


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