Localized Surface Plasmon Resonance Enhancement Research Articles

Localized surface plasmon resonance (LSPR) excitation on single silver nanoring with nanoscale surface roughness

With the expansion of the application of high-sensitivity Surface-enhanced Raman scattering (SERS) technique, micro SERS-active substrates with rich optical properties and high-level functions are desired. In this study, silver nanorings with nanoscale surface roughness were fabricated as a new type of enclosed quasi-2D micro-SERS-active substrate. Highly-crystalline spherical and hemispherical silver nanoprotrusions were densely and uniformly distributed over the entire surface of the nanorings. The SERS signals were significantly enhanced on the roughened silver nanorings which were mainly derived from the maximal localized surface plasmon resonance (LSPR) points at the junctions between adjacent coupled nanoprotrusions on the roughened nanorings. The mapping image shows a uniform and intense LSPR enhancement over the nanorings, owing to the uniform and dense distribution of silver nanoprotrusions and the resulting uniform distribution of maximal LSPR points on the roughened nanorings. The dark-field spectra further indicated that the single roughened silver nanoring had significant LSPR enhancement, a wide LSPR frequency-range response, and adaptability for SERS enhancement. Notably, both the measured and simulated results demonstrate that the maximal LSPR enhancement at the junctions between the nanoprotrusions, which are distributed on the inner surface of the silver nanoring, is higher than that on the outer surface because of the plasmon-focusing effect of the enclosed silver nanoring, which leads to the lateral asymmetrical distribution of LSPR intensity, indicating more LSPR and SERS features. These results indicate that single roughened silver nanorings exhibit excellent performance as a new type of enclosed quasi-2D silver nanoring micro-SERS-active substrate, microzone LSPR catalysis, and micro/nanodevices.

Design of an efficient ultra-thin film Cu(In,Ga)Se2 solar cell, using plasmonic cluster back reflectors

In this paper, an ultra-thin film CIGS solar cell using a cluster back reflector is discussed to improve optical parameters. This cluster nanostructure includes four silver nanoparticles embedded in the back surface of the active layer. By optimizing the effective parameters of the plasmonic phenomenon, such as length, width, height, and distances between the nanoparticles, among the studied cases, the cylindrical nanostructure, is selected as the most efficient back reflector. To achieve these results, it is mainly focused on short-circuit current density analysis. Besides, power conversion efficiency, absorption spectrum and transmission of light are also studied. As a result, due to the localized surface plasmon resonance enhancement, short-circuit current density and power conversion efficiency reach 27.2 mA/cm2 and 15.7 %, respectively. These values for the bare state were 19 mA/cm2 and 10.7 %.

Advanced electrochromic properties of Nb-doped WO3 inverse opal films in NIR region by slow photon effect-assisted enhancement of localized surface plasmon resonance

Among various methods to enhance light harvest, opal and inverse opal with periodicity in structure are indisputable one of the best solutions. In this view, inverse opal (IO) was introduced in Nb-doped WO3 film to assist localized surface plasmon resonance (LSPR), aiming to enhance electrochromic optical contrast in near infrared (NIR) region. The obtained Nb-doped WO3 inverse opal (IO) film demonstrates its advantage with an optical contrast of 60.4% at 1100 nm wavelength, nearly twice higher than its plain film counterpart (29.1%) and 5 times higher than undoped WO3 IO film (11%). Such extraordinary property is attributed to slow photon effect assisted enhancement of LSPR: in addition to oxygen vacancies due to Nb dopant, a much longer lifetime of free carriers (11.84 ns) arising from slow photon effect of inverse opal, which is double to that of its plain film counterpart (6.72 ns), renders a great increase in photonic absorption and further an enhancement of LSPR under light incident condition. The success of present strategy can be extended to rationally design other related devices.

Design of broadband high efficiency absorption antenna based on metamaterial nano-ring array

Compared with the traditional solar cells, the nano-optical antenna breaks through the band-gap limitation of semiconductor materials, and provides a new scheme for solar energy collection. In order to solve the problems of complex structure, low efficiency and narrow bandwidth of nano-optical antenna, a novel nano-ring-cylinder based on metamaterials is proposed in this paper. The antenna has an average absorption efficiency of 96.93% in the wide-band absorption range of visible and near-infrared light. First of all, the basic design theory of the antenna was given based on the surface plasma theory. Then, the antenna structure design scheme was determined, the overall structure consists of two layers of metal and an insulating layer formed by Al2O3. Finally, on the basis of the established antenna model, the absorption characteristics were analyzed by simulation. The analysis result shows that the super-absorption ability of the antenna is independent of the polarization of the incident light, and the average absorption ability can be maintained at about 91% when the incident angle is ±60°. The absorption capability of the antenna is mainly due to the synergistic effect of Fabry-Perot resonance and localized surface plasmon resonance enhancement. The conclusion can provide a theoretical guidance for the structural design of nano-optical antenna.

Endorsing a Hidden Plasmonic Mode for Enhancement of LSPR Sensing Performance in Evolved Metal-insulator Geometry Using an Unsupervised Machine Learning Algorithm.

Large-area nanoplasmonic structures with pillared metal-insulator geometry, also called nanomushrooms (NM), consist of an active spherical-shaped plasmonic material such as gold as its cap and silicon dioxide as its stem. NM is a geometry which evolves from its precursor, nanoislands (NI) consisting of aforementioned spherical structures on flat silicon dioxide substrates, via selective physical or chemical etching of the silicon dioxide. The NM geometry is well-known to provide enhanced localized surface plasmon resonance (LSPR) sensitivity in biosensing applications as compared to NI. However, precise optical phenomenon behind this enhancement is unknown and often associated with the existence of electric fields in the large fraction of the spatial region between the pillars of NM, usually accessible by the biomolecules. Here, we uncover the association of LSPR enhancement in such geometries with a hidden plasmonic mode by conducting magneto-optics measurements and by deconvoluting the absorbance spectra obtained during the local refractive index change of the NM and NI geometries. By the virtue of principal component analysis, an unsupervised machine learning technique, we observe an explicit relationship between the deconvoluted modes of LSPR, the differential absorption of left and right circular polarized light, and the refractive index sensitivity of the LSPR sensor. Our findings may lead to the development of new approaches to extract unknown properties of plasmonic materials or establish new fundamental relationships between less understood photonic properties of nanomaterials.

Localized Surface‐Plasmon Enhanced Near‐Infrared Organic Photodetector

AbstractNear infrared (NIR) organic photodetector (OPD) has exhibited tremendous potential in research due to mechanical flexibility, optoelectronic tunability, and low cost. However, the limited NIR light absorption, low carrier mobility, and relatively low photon‐to‐electron conversion efficiency in organic photoactive layer have restricted further development of OPD. To address these challenges, localized surface‐plasmon resonance (LSPR) enhanced D18:Y6 OPD is systematically designed and fabricated with uniform Ag nanocubes (AgNCs) of 60 nm deposited right on D18:Y6 organic photoactive layers, realizing a 25‐fold enhancement in responsivity and detectivity which reach 2200 mA W−1 and 2.8 × 1012 Jones, respectively, upon 850 nm laser excitation compared with pristine device without AgNCs. The detailed COMSOL Physics simulation of as‐obtained devices with AgNCs indicates that electric filed is strongly amplified and concentrated within the D18:Y6 film. The enhancement of photoluminescence intensity in D18:Y6 films with AgNCs further verifies the resonant enhancement of light absorption in the D18:Y6 film embedded with AgNCs. To get in‐depth knowledge of the LSPR enhancement effect on OPD, the photocurrent enhancement of devices with different laser power densities and plasmonic modes have been systematically explored. Therefore, this work has opened a new window to enhance the photoresponse for next generation NIR OPDs.

Two-in-one: Portable piezoelectric and plasmonic exciton effect-based co-enhanced photoelectrochemical biosensor for point-of-care testing of low-abundance cancer markers

In-depth exploration of the local surface plasmon resonance and piezoelectric effects associated with metal can help develop efficient biosensors. Here, we presented for the first time the localized surface plasmon resonance (LSPR) and piezoelectric effects co-enhance the construction of an efficient intra-body phase electric field for the construction of efficient photoelectrochemical (PEC) biosensors. Briefly, the LSPR enhancement and piezoelectric enhancement effects between Ag nanoparticles and the piezoelectric material NaNbO3 were investigated in a PEC biosensor system under the excitation of portable UV light. Notably, the simplified treatment of the basic building blocks of the PEC sensor, including a handheld UV flashlight instead of a physical excitation light source and a digital multimeter instead of an electrochemical workstation. The capture and immunoincubation process of target PSA occurs on separated microtiter plates and hydrogen peroxide, generated by enzyme-linked immunization, induces the directional separation of electrons and holes in the composite heterogeneous material under the excitation of light. The coupling with a digital multimeter allows for real-time monitoring of photocurrents. Further, the effect of Ag deposition on piezoelectric perovskite NaNbO3 was obtained by density functional theory (DFT) calculations. Impressively, under optimized conditions, the system exhibits an ultra-wide linear range and ultra-low detection limits for the target PSA. The system is also comparable to commercially available ELISA kits at the 95% confidence level. This work provides a novel idea of enhanced PEC biosensor for rapid and accurate detection of cancer-related proteins.

Visible light assisted trace gaseous NO2 sensor with anti-humidity ability via LSPR enhancement effect

Transition metal dichalcogenides (TMDs) have been received widespread attention for NO2 detection at room temperature. However, the TMDs-based gas sensors usually possess inferior response capability and suffer from humidity interference due to lack of sufficient reaction activation energy, which seems tough to achieve the detection of ppb-level gases and hinder the practical applications. Herein, we propose a visible light-assisted-type gas sensor based on Au-decorated WS2, endowing high-performance detection of NO2 at room temperature. Benefited from the localized surface plasmon resonance (LSPR) enhancement effect induced by the modified Au nanoparticles (NPs), the visible light-assisted Au/WS2 gas sensor can implement the detection of NO2 gas as low as 20 ppb. Moreover, the maximum drift of the sensor response value is only 3% in the range of 10%−90% RH, indicating the stabilized anti-humidity ability. The effective regulation of transmission channel by the modified noble metal and the enhancement of visible light absorption of WS2 through taking full advantage of the LSPR effect are the main reasons for realizing low concentration detection and improving the anti-humidity ability. Therefore, the visible light-assisted gas detection mode can serve as a proof-of-concept to provide an effective approach for the detection of trace gases at room temperature.

Broadband Absorption Antenna Based on High Refractive Index Tungsten Metal-Insulator-Meta Metamaterial Nano Ring Array

Antennas for solar energy collection, for the problem of complex antenna structure and narrow absorption band, a metal-insulator-metal (MIM) nano ring array antenna based on metamaterial is proposed, which has high-efficiency light absorption characteristics in the broadband range of visible light and near-infrared light. Based on surface plasma theory, the proposed antenna is only composed of two W layers of metal and one Al2O3 layer of insulator medium, and has an a verage absorption rate of 96.93% in the range of 400–1600 nm. In addition, it is found that this kind of super light-absorbing capability is independent of the incoming light polarization state and can maintain an average of 91% for an incident angle as large as±60°. Furthermore, the perfect absorption performance of MIM nano ring array antenna based on metamaterial can be explained by the synergistic effect of localized surface plasmon resonance enhancement and Fabry-Perot resonance.

Figure of merit and sensitivity enhancement of biosensor LSPR in investigated for visible and near infrared

We have proposed new localized surface plasmon (LSP) hybrid nanostructures, based on gold nanowires form T (AuNWs-T) deposited on a glass substrate (substrate/AuNWs) or on a graphene-coated Au film (substrate/Au film/graphene/AuNWs). The results have shown that by optimizing the parameters of nanoplasmonic structures and the incidence angle of the excitation wave. This study gives an ultra-detection performance. The detection performance parameters expressed in terms of figure of Merit (FoM) and sensitivity are improved to more than 593% (7 times) for FoM and 284.86% (3.85 times) the sensitivity compared to a traditional AuNWs-based LSPR nanostructure in normal incidence. Due to the improvement of localized surface plasmon resonance (LSPR) which is attributed to the effect of coupling between the AuNWs-T and graphene-coated Au film. This complicated nanoplasmonic resonance LSPR enhancement with the incident angle, especially in the presence of gold nanowires, can be controlled reliably by engineering the dispersion curve. These results are followed by an enhancement of the calculated electric field strength along several cut lines through the hybrid nanostructures. Our results show that the hybrid nanostructures devices hold great promise as biosensors for different types of analytes and for optical nanotechnologies.

Plasmonic perovskite solar cells: An overview from metal particle structure to device design

In the past decade, the perovskite solar cells (PSC) have become one of the most emerging alternatives for the next generation of photovoltaic technologies and the power conversion efficiency (PCE) of PSCs has reached 25.5%. Among the various approaches developed toward efficient PSCs, the implementation of plasmonic meta-nanoparticles (MNPs) into the device is a versatile approach to enhance the performance of PSCs by tailoring the optical properties and charge-transport dynamics of the solar cells. Numerous recent studies have shown that the localized surface plasmon resonance (LSPR) of the MNPs is closely related to their morphology, size, composition and structure, and the achieved plasmonic enhancements in PSCs are thus diverse. In this review, we first briefly discussed the working principle of LSPR of MNPs, and the effects of the morphology, composition, and structure of plasmon nanoparticles on their LSPR properties are then summarized. Next, an overview of the enhancing mechanism and recent research progress of LSPR in PSC is conducted. Subsequently, some basic principles of device design to realize the full potential of LSPR enhancement are provided. Finally, the opportunities and challenges that may be encountered in the future development of plasmonic PSC are concluded.

Photogenerated carrier separation and localized surface plasmon resonance in SnS2@AuNPs Janus heterostructures for enhanced visible light catalysis

We compare the visible light extinction difference of Janus and core-shell structures for several typical semiconductors and gold nanoparticles (AuNPs) and found out better extinction behavior of the Janus type with visible light response for narrow bandgap semiconductors. Following the predictions, we designed and prepared the Janus and core-shell heterostructures of SnS2 (Eg = 2.1–2.4 eV) and AuNPs (SnS2@AuNPs). Excellent visible light catalytic performance in Janus structures compared with SnS2 and the core-shell structures can be observed, which was attributed to the enhanced localized surface plasmon resonance (LSPR) and the increased lifetime of photo generated carriers. The absorption spectrum revealed more significant LSPR intensities for the Janus structures compared to SnS2 and the core-shell structures. The Photoluminescence (PL) spectrum of the core-shell and Janus structures showed a half and a quarter the intensities of the SnS2. The shorter lifetime in Janus structures (1.16 ns) may result from the fast depopulation of photo-generated electrons from SnS2 into Au. Due to the LSPR enhancement and the photo generated carriers separation in the Janus structures, the visible light catalytic performance of SnS2 has been improved effectively.

Interparticle Distance Effect on the Optical Response of Platinum Dimer Nanoparticles

This article describes the plasmonic coupling effect on the Localized Surface Plasmon Resonance (LSPR) of Platinum (Pt) dimer nanoparticles. The effect of the dielectric medium on the optical response is also calculated for the Pt dimer. The optical extinction spectra have been investigated over a broad spectral range (from the visible to the near infra-red). Measurements were performed using a numerical method based on Finite Element Method (FEM) which permits the determination of both the interparticle distance and the polarization effects on the LSPR. A clear enhancement of LSPR has been appeared for a longitudinal polarization compared to a transversal one. Furthermore, plasmonic coupling induces a tunable red-shifting and broadening of LSPR in dimers by decreasing the interparticle distance.

TiO2 film supported by vertically aligned gold nanorod superlattice array for enhanced photocatalytic hydrogen evolution

Photocatalytic hydrogen generation from water as a renewable non-polluting technique for converting solar energy to chemical energy has recently attracted worldwide attention. However, low hydrogen production efficiency of traditional photocatalysis still remains as a challenge. Here, we report a large area TiO2 film supported by vertically ordered Au nanorods superlattice array (O-AuNRs/TiO2), which demonstrates excellent photocatalytic performances of hydrogen evolution from water under solar and visible light irradiation. The O-AuNRs/TiO2 architecture enables the significant localized surface plasmon resonance (LSPR) enhancement, including both local electromagnetic field effect and hot electron transfer effect, which promotes the photocatalytic hydrogen evolution rate of the TiO2 film by 58 times. The photocatalytic efficiency of O-AuNRs/TiO2 exceeds that of the TiO2 film supported by randomly oriented AuNRs by over five times. Finite difference time domain (FDTD) modeling results support that the strong coupling of O-AuNRs enhances the electromagnetic field intensity along the longitudinal axis in the gaps between adjacent AuNRs and the average electric field enhancement factors at the interface between the AuNRs and TiO2 of O-AuNRs/TiO2. This work demonstrates the substantial performance boost of conventional photocatalyst by LSPR enhancement, thus provides a promising tactic to devise highly efficient photocatalytic system for solar energy conversion.

Growing In‐Plane Multiplex Plasmonic Arrays for Synergistic Enhanced Photocurrent Response

AbstractA complete control of the localized surface plasmon resonance (LSPR) properties of different types of metal nanoparticles (size, shape, or composition) in a device by facile techniques with high throughput is crucial to intensively study and apply the LSPR effects to improve device performance. Here, a versatile approach is presented to fabricate macroscopic and in‐plane multiplex arrays of plasmonic nanoparticles with well‐defined particle size or composition allocation. The polymer layer (poly(N‐isopropylacrylamide), PNIPAM) spin‐coated on the surface of the substrate is applied as a protective layer to control the growth of the Au nanoparticles in a dip‐coating procedure. The relative contribution of LSPR of each particle type can be controlled by selectively adjusting the particle size or composition at the desired position of multiplex arrays on the same substrate. A synergistic enhanced photocurrent response is observed in the metal–semiconductor system, which is attributed to broadened LSPR enhancement of multiplex composition (Au and Au@Ag) structures from the same substrate. The fabrication procedure presented in this study is highly repeatable and feasible for preparing ordered multiplex nanostructures on the same substrate. Furthermore, this method provides a cost‐effective and versatile platform for design of multiplex plasmonic nanostructures in sensing, solar energy conversion, and optical processing applications.

Surface-enhanced Raman scattering studies of Cu/Cu2O Core-shell NPs obtained by laser ablation.

In order to perform SERS (surface-enhanced Raman scattering) measurements, spherical Cu/Cu2O core-shell NPs with a rather rough rugged surface and well-defined crystallographic structures were fabricated using nanosecond Ce: Nd YAG pulsed laser ablation in liquid (PLAL). Raman, Fourier transform infrared (FTIR) spectroscopy and TEM imaging of the prepared NPs reveal the existence of additional minority CuO phase, not determined earlier through XRD patterns. The SERS activity of Cu/Cu2O core-shell NPs substrates was investigated by using crystal violet (CV) and methylene blue (MB) as the analyte molecules under 532 nm excitation wavelength irradiation. The effect of localized surface plasmon resonance (LSPR) from Cu core contributing to the electromagnetic enhancement and Cu2O shell with a rough surface which itself contributes to chemical enhancement with adsorbed analyte molecule is due to a high overall SERS enhancement. The intensities of the totally and non-totally symmetric modes were used to calculate the degree of charge-transfer. The results demonstrate that the LSPR enhancement dominates charge-transfer resonance contribution in SERS of Cu/Cu2O-CV and Cu/Cu2O -MB systems. The reproducibility of the prepared SERS substrates was investigated and the SERS signals intensity variation was <28%.

Optimization Design of a Multi-slot Nanoantenna Based on Genetic Algorithm for Energy Harvesting

A new genetic algorithm (GA)-based multi-slot nanoantenna is proposed for energy harvesting, which consists of two element nanoantennas with rectangular shape and with double bowtie double ring (DBDR) slot. The DBDR slot structure can enhance the electric field to increase the absorptivity of nanoantennas; however, the larger parameter space of multi-slot is more hardly controlled. Therefore, we use GA to optimize the parameters of the DBDR slot nanoantenna and the Finite-Difference Time-Domain method to calculate the absorptivity. It is found that absorptivity of the optimized nanoantenna is over 77% in 400–1800 nm waveband. We attribute the better absorbing property of the nanoantenna to the synergistic effect of the localized surface plasmon resonance enhancement and coupling between slots.

Localized Surface Plasmon Resonance Enhanced Photocatalytic Hydrogen Evolution via Pt@Au NRs/C3N4 Nanotubes under Visible‐Light Irradiation

AbstractAu nanorods (NRs) decorated carbon nitride nanotubes (Au NRs/CNNTs) photocatalysts have been designed and prepared by impregnation–annealing approach. Localized surface plasmon resonance (LSPR) peaks of Au NRs can be adjusted by changing the aspect ratios, and the light absorption range of Au NRs/CNNTs is extended to longer wavelength even near‐infrared light. Optimal composition of Pt@Au NR769/CNNT650 has been achieved by adjusting the LSPR peaks of Au NRs and further depositing Pt nanoparticles (NPs), and the photocatalytic H2 evolution rate is 207.0 µmol h−1 (20 mg catalyst). Preliminary LSPR enhancement photocatalytic mechanism is suggested. On one hand, LSPR of Au NRs is beneficial for visible‐light utilization. On the other hand, Pt NPs and Au NRs have a synergetic enhancement effect on photocatalytic H2 evolution of CNNTs, in which the local electromagnetic field can improve the photogenerated carrier separation and direct electron transfer increases the hot electron concentration while Au NRs as the electron channel can well restrain charge recombination, finally Pt as co‐catalyst can boost H+ reduction rate. This work provides a new way to develop efficient photocatalysts for splitting water, which can simultaneously extend light absorption range and facilitate carrier generation, transportation and reduce carrier recombination.

Enhancement of a Cu2O/ZnO photodetector via surface plasmon resonance induced by Ag nanoparticles

The localized surface plasmon resonance enhancement of a Cu2O photodetector was realized by Ag nanoparticles (NPs) that were fabricated by electrochemical deposition. A ZnO nanowire was used to accelerate carrier separation. An increase of responsivity was achieved based on the coupling interaction between the surface plasmon resonance in the Ag NPs and the Cu2O film. The photodetector possessed high responsivity (0.27A/W). Compared to the device without Ag NPs, the responsivity was enhanced 20-fold. The excellent comprehensive performance of the Cu2O/ZnO photodetector reveals that localized surface plasmon resonance is an efficient way to improve the performance of Cu2O-based photodetectors.

Tunable plasmon-enhanced broadband light harvesting for perovskite solar cells

In this work, we report a reliable method for synthesizing (Au, Au/Ag core)/(TiO2 shell) nanostructures with their plasmonic wavelengths covering the visible light region for perovskite solar cells. The mono- and bi-metallic core-shell nanoparticles exhibit tunable localized surface plasmon resonance wavelength and function as “light tentacle” to improve the photo-electricity conversion efficiency. Plasmonic nanoparticles with different sizes and shapes, different thicknesses of TiO2 shell and Ag interlayer are found to have a strong influence on the localized surface plasmon resonance enhancement effect. The experimental photovoltaic performance of perovskite solar cells is significantly enhanced when the plasmonic nanoparticles are embedded inmesoporous TiO2 scaffolds. A champion photo-electricity conversion efficiency of 17.85% is achieved with nanoparticles (Au/Ag, λLSPR = 650 nm), giving a 18.7% enhancement over that of the pristine device (15.04%). Finite-difference time-domain simulations show that nanorod Au in mesoporus TiO2 scaffold induces the most intense electromagnetic coupling, and provides a novel emitter for photon flux in mesoporous perovskite solar cells. These theoretical results are consistent with the corresponding experimental those. Thus, enhancing the incident light intensities around 650 nm will be most favorable to the improvement of the photo-electricity conversion efficiency of perovskite solar cells.